Final Report Project #28 Diagnosis tool for cage induction ...

Aalto University, School of Electrical Engineering Automation and Electrical Engineering (AEE) Master's Programme ELEC-E8004 Project work course Year 2018

Final Report

Project #28 Diagnosis tool for cage induction machine rotor

Date: 20.5.2018

Jouni Lahtinen Jani Sormunen Mark Nortamo

İsmet Tuna Gürbüz

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Information page Students Jouni Lahtinen Jani Sormunen Mark Nortam İsmet Tuna Gürbüz Project manager Jouni Lahtinen Official Instructor Aswin Balasubramanian Starting date 5.1.2018 Completion date 20.5.2018 Approval The Instructor has accepted the final version of this document Date: 20.5.2018

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Abstract The aim of this project was to design a diagnosis tool for squirrel cage induction motor to analyze the impedance of aluminum rotor bars. Porosities and broken bars in aluminum bars causes an increase in the impedance leading to deterioration in motor performance. Our aim was to design a flux injection probe and measure the impedance of rotor bars and detect the locations of the porosities and broken bars accordingly. In this project, firstly, we have achieved to implement the model of the rotor and flux injection probe into FEMM program and taken reasonable simulation results. Afterwards, we have achieved to design the flux injection probe experimentally after the simulations. In order to place the flux injection probe accurately, a stand has been made so that probe can be kept steady and can move along the long axis of rotor firmly. By using a power supply, flux is injected through rotor bars, and impedance measurements are taken from different positions of the rotor as rotor rotates. The data of the impedances of different positions are obtained as a function of rotation angle (using encoder) and distance in the movement axis of probe (using distance sensor). The obtained data has been combined in the computer properly. By using these data, we have achieved to detect the location of the possible porosities and broken bars correctly. While the impedance values are increasing slightly for possible porosities, the change of impedance for the broken bars are more significant.

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Table of Contents Abstract .......................................................................................................................................... 3

Table of Contents ............................................................................................................................ 4

1. Introduction............................................................................................................................. 5

2. Objective ................................................................................................................................. 6

3. Project plan ............................................................................................................................. 7

3.1. Expected output ............................................................................................................... 7

3.2. Milestones ....................................................................................................................... 7

3.3. Cost plan and materials .................................................................................................... 7

4. Results A ................................................................................................................................ 7

4.1. Simulations in FEMM ..................................................................................................... 7

4.2. Impedance Calculation Approach .................................................................................... 9

4.3. Results of Simulations ................................................................................................... 10

5. Results B ............................................................................................................................... 12

5.1. Probe and stand ............................................................................................................. 12

5.2. Arduino and sensors ...................................................................................................... 13

5.3. Combining results with Excel ........................................................................................ 15

5.4. Measuring ..................................................................................................................... 16

5.5. Measured impedances.................................................................................................... 17

6. Reflection of the Project ........................................................................................................ 18

6.1. Reaching objective ........................................................................................................ 18

6.2. Timetable ...................................................................................................................... 18

6.3. Risk analysis ................................................................................................................. 18

6.4. Project Meetings ............................................................................................................ 19

6.5. Quality management ...................................................................................................... 20

7. Discussion and Conclusions .................................................................................................. 20

List of Appendixes ........................................................................................................................ 21

References .................................................................................................................................... 21

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1. Introduction There is no doubt that energy is one of the most important essential needs of mankind. It is not possible to think about any part of our life without energy. 22% of this energy is used in the form of electricity and 40% of electricity is used by electric motors. There is a wide range of usage of electric motors from our small household equipment to the big devices in the factory. There are different types of electric machines and they can be categorized as follows;

Figure 1: Electric Motors [1]

From above categories, our scope is induction (asynchronous) motors. Induction motors are used all over the world with a wide range of applications. The most common used induction motors are squirrel cage induction motors. There are mainly two types of rotors used in squirrel cage induction motors as copper rotors and aluminum die-cast rotors. Copper rotor bars are the mainly used ones in these machines. However, recently, aluminum die- cast rotors have become more popular for the manufacturers more than copper rotors to drop manufacturing cost to compete in global market. As it is known, for the same amount of aluminum and copper, aluminum is much cheaper; therefore, it is considered to be a good idea to use aluminum for economic reasons. This can decrease the costs up to 20%. In order to give a desired shape to the rotor bars, aluminum die-cast process is done. Die-casting is a process where the aluminum is molted under high pressure in the mold cavities. The metals are hardened and desired shapes are produced. Aluminum die-casting can be made with the use of either hot chamber or cold chamber. However, the die-casting process may cause some problems in aluminum bars. Porosity in aluminum die-cast squirrel cage rotors is inevitably introduced during the die-cast process. Porosity may lead to degradation in motor performance and outages causing irreversible damages. There are plenty of ongoing tests to measure the quality of rotor; however, the results of these tests have shown that they are not sufficient enough to have sensitive data.

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In this project, we have worked on designing a flux injection device in order to detect the varied levels of porosity and monitor the defects caused in the manufacturing process such as broken bars in rotor slots. For this purpose, we have gone through different phases, mainly as;

- Implementation of rotor model and probe to FEMM, and simulation of the system - Design and building of the setup (probe, stand, sensors, supply etc.) - Testing the setup

After the reasonable simulation results, a probe has been designed according to simulations. The design details will be given in the following sections but at this part, we will explain the flux injection process briefly. The flux injection device has been made up of U-shaped ferromagnetic core and excitation windings to generate magnetomotive force to be used in flux injection. As the rotor rotates with a low speed, the designed probe injects flux to the rotor bars. This flux injection device is used for

1. Excitation of the bars and end rings with AC voltage applied 2. Monitoring the rotor by the voltage and current measurements in the coil

The main core of our product is to analyze the rotor impedance. When the rotor bars are exposed to porosities, the equivalent rotor impedance increases. The equivalent circuit in case of porosity can be modeled as follows;

Above figure implies that as the porosity increases, the equivalent resistance increases. By using this probe, the aim is to measure the impedance of each rotor slots. If the impedance is more than a specified range, it means that there is porosity in that slot. The impedance measurements will give an insight into the porosity level according to the range of impedance value. After the design of the probe, a stand has been designed so that probe can be placed accurately (perpendicular to the axis of bars without touching the rotor). 1 distance sensor and an encoder have been located on the stand in order to pinpoint the position of the measured point. Using power supply, flux is injected to rotor bars, and voltage and current measurements are taken from the bars. By using voltage/current division, impedance is found together with the distance and rotation angle with the help of distance sensor and encoder.

2. Objective The main objective of the project was to analyze the impedance of rotor bars at different positions by injecting flux via a probe. With the analysis, we were expecting to detect the defects caused in the manufacturing processes such as porosity or broken bars on the points where the impedance gets more

Figure 2: Equivalent Circuit of Device and Rotor Slots Under Excitation [2]

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than the normal value. The objective was to decide those points by using the impedance map of the rotor and as a function of distance and rotation angle. As an addition to the main objective, one of the goals was to improve our group skills in terms of both communication and cooperation. Another goal was to achieve the main objective and to contribute to the manufacturers or users by enabling them to have an insight on the defects.

3. Project plan In the Project plan is defined expected output, phases of this project, responsibilities, risks and estimations for schedule and costs. We have been able to follow our project plan quite well. Following chapters discuss more deeply about relevant aspects of Project plan.

3.1. Expected output We have marked to the Project plan, that our expected output is to make the flux injection device to analyze is the rotor in good condition. Impedance of the squirrel cage induction machine rotor is measured with flux injection probe. Rotor has to be die-casted aluminum rotor. Project plan also points out, that person with basic knowledge in electromechanics is able to find the fault locations from the rotor with the device.

3.2. Milestones The most important milestones for this project were to make a working simulation with actual specifications of the model, complete diagnostics tool, detect a deviation in a predetermined faulty rotor and to complete final report. We have achieved first three milestones and now we have to catch up schedule little bit to be able to finish the project on the schedule.

3.3. Cost plan and materials Our budget for this project was 1000 €, but in Project plan we estimated that we need something between 400 € and 550 €. We needed to pay for cutting and buy rotary encoder, distance sensor and Arduino. Other materials like metals for the stand, power supply and voltage - and current meters we had already in the electromechanics laboratory.

4. Results A

4.1. Simulations in FEMM The first phase of the project was to implement the design of rotor to a simulation program called FEMM and to take the results for different cases. As it is known, the aim of the project is to analyze rotor impedance for the cases of a healthy rotor bar, a bar with porosity and a broken bar. Therefore, before implementing our designing tool to make those analyses, it is needed to simulate it. For the simulation, first, we have begun with the implementation of the rotor. The data of rotor can be given as;

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Rotor inner diameter: 54 mm Rotor outer diameter: 124 mm Number of bars: 40 (9o separated from each other) This model was implemented as below;

Figure 3: Rotor Diagram

Here, aluminum represents the material of rotor bars. The inner circle is shown as air since it is empty. M-19 Steel is the type of the rotor steel. After drawing the rotor, flux injection probe has been designed so that it covers 5 bars and implemented as below;

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Figure 4: Flux Injection Probe Diagram

In above figure [Coil = 300] and [Coil = -300] stands for the number of terms. After the implementation of above diagrams, simulations between different cases have been performed. The cases that we have simulated are simply as follows; I) Healthy Bar II) Bar with Air Hole III) Broken Bar 1st case is simulated with the diagram in Figure 3 (with aluminum material in rotor bars). 2nd case is simulated by placing air holes in the aluminum material. 3rd case is simulated by replacing the aluminum material with air.

4.2. Impedance Calculation Approach While simulating those cases, different values of current [Amperes] and frequency [Hertz] have been used with a constant number of turns which is 300. In order to calculate flux and impedance, following formulas have been used; 𝛷(𝑡) = 𝛷&'( sin(𝑤𝑡)(𝑠𝑖𝑛𝑢𝑠𝑜𝑖𝑑𝑎𝑙𝑓𝑙𝑢𝑥)

𝑒(𝑡) = 𝑁𝑑𝛷𝑑𝑡 = 𝑁𝛷&'(𝑤 cos(𝑤𝑡) = 𝐸&'( cos(𝑤𝑡)(𝑠𝑖𝑛𝑢𝑠𝑜𝑖𝑑𝑎𝑙𝑣𝑜𝑙𝑡𝑎𝑔𝑒)

𝑤 = 2𝜋𝑓, 𝐸&'( = 2𝜋𝑓𝑁𝛷&'(

𝐸B&C =2𝜋√2

𝑁𝑓𝛷&'( = 4,44𝑁𝑓𝛷&'((𝑟𝑚𝑠𝑣𝑎𝑙𝑢𝑒)

Firstly, we measure the flux and put this flux to the above equation. After calculating voltage rms value, the impedance is found as follows;

𝑍 =𝐸B&C𝑖B&C

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4.3. Results of Simulations We have taken lots of cases (different values of current, frequency, turn ratio etc.); however, we will not put all the cases in this report. We will put some of the results as;

Case Current (A)

Number of Turns

Freq. (Hertz) Flux (Tesla) Impedance

(Ohm)

Real Part of Impedance

(Ohm)

Imaginary Part of Impedance

(Ohm)

Angle (Radian)

Healthy 2 300 50 0.0000573376-j0.00000023341

2.701970744-j0.01099937561 2.70197074 -0.01099937561 -0.23324

1 Airhole in a Bar

2 300 50 0.0000573376-j0,00000023365

2.701970744-j0.01101063822 2.70197074 -0.01101063822 -0.23348

Air in 5 Bars 2 300 50 0.0000573381-

j0,00000023377 2.701994306-j0.0110165287 2.70199430 -0.01101652870 -0.23360

Healthy 4 300 50 0.00011448-j0.00000046815

2.697371452-j0.0110305245 2.69737145 -0.01103052450 -0.23430

1 Airhole in a Bar

4 300 50 0.000114481-j0.00000046840

2.697395014-j0.0110365092 2.69739501 -0.01103650920 -0.23443

Healthy 7 300 50 0.000172194-j0.00000061963

2.318414595-j0.008342773 2.3184146 -0.00834277300 -0.20618

1 Airhole in a Bar

7 300 50 0.000172194-j0.00000061990

2.318481914-j0.00834639486 2.31848191 -0.00834639486 -0.20626

Table 1: Results of the Simulation

Results show us that, impedance changes after 5th decimal digit which makes our approximation viable. In next page, we will show the flux lines according to the simulation results for healthy and 1 hole with air cases.

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Figure 5: Flux Lines for Healthy Case

Figure 6: Flux Lines for 1 Air Hole Case

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5. Results B

5.1. Probe and stand According to the simulation drawings and our design, the dimensions of the flux injection probe is as follows;

Figure 7: Flux Injection Probe Dimensions

It is designed so that it can inject flux to the 5 slots. In order to construct the probe, firstly we have cut steel sheets and these sheets have been sent to a workshop so that they could be shaped and glued. After we took it back, we have wound 300 turns of the coil to the combined sheets. Then, both sides of the probe have been placed between a platform so that it could stay fixed while moving it. Also, cables coming from the power supply are connected to the probe as can be seen in Figure 8.

Figure 8: Probe

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After the construction of probe, a stand has been constructed. It is used to place rotor accurately parallel to the ground and to a fixed position. Also, on the stand, there is a platform to place the rotor so that flux can move in one axis as the rotor rotates. Figure 9 shows the stand, rotor, and probe together.

Figure 9: Rotor, Stand and Probe

5.2. Arduino and sensors In this project, Arduino UNO was used to read and transfer the data from the sensors to the excel-file. Sensors that we used were distance sensor and rotary encoder. The distance sensor is used to measure the position of the probe and the rotary encoder is used to determine the angle of the rotor. That data is used with measurement data to determine the location of porosity and broken rotor bars.

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Figure 10: Wiring diagram.

In Figure 10 can be seen how the distance sensors, rotary encoder, and button are connected to Arduino. The rotary encoder that was used is AEAT-6010-A06 and it is manufactured by Broadcom Limited. This encoder is an absolute 10-bit magnetic encoder. An absolute encoder means that the position information is maintained although the power is turned off. This is a good feature for the encoder in this project because if position information is incorrect then all previous measurements are ruined. The distance sensor that was used is VL53L0X manufactured by Adafruit. It is so called “time of flight distance sensor”. It calculates the distance of the object by measuring the time what it takes for a light to go to object and bounce back to sensor. This sensor type worked well to detect the position of probe relation to the rotor. The code which is used to control sensors and transfer the data from them in right format can be found in the appendixes as Appendix I. The main idea how code works is following: when the button is pushed, Arduino starts to read values of distance sensor and rotary encoder and then the excel macro reads data via serial port and writes it in the excel in format what can be seen in Figure 11. Writing to the excel can be stopped by pushing the button the second time.

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The macro which is used to get data from Arduino to excel was found in Arduino forums [3]. It is called as PLX DAQ v2. The only thing that needs to be to add to Arduino code is to make right form Serial.println commands to get this macro work. When the Arduino codes are in right form, the data can get easily to the excel by opening the excel, which includes the macro and then push the connect-button and then the data starts to flow into the excel. The data that is written in to excel includes date and time when the measurements are done and also the probe distance information and the angle of the rotor. In chapter Combining results with Excel is told more about how this data is used.

5.3. Combining results with Excel The impedance measurements were done with two Agilent Technologies 34410A. The first one measured the voltage over the probe and the second one measured the current passing through the probe. With these measured values using the measurement computer located in the electromechanics laboratory, we acquired the impedance of the circuit. The final Agilent measurement together with the computer automatically created a file of the voltage, current and impedance results in addition to the time stamp. As explained in chapter Arduino and sensors we got a long Excel file of the measured distance and angles together with the time step. Now the objective was to combine the impedance values together with the distance and angle values. The first mission was to create text files of the Agilent measured impedance values so the Excel macros will be able to read these files. This was done by using the built-in Windows PowerShell (WPS) application. Firstly, locate the folder of the files you want to change by maneuvering with WPS with the following command: Set-Location -Path “Path_of_the_folder”. For example: “Set-Location -Path C:\Users\Mark\ChangeName”.

Figure 11: Excel sheet that includes macro for reading Arduino.

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Then by using the following command, you will change all the names of the files in that directory: “dir | rename-item -NewName {$_.name -replace "what_should_be_added","what_should_be_removed"}”. As we wanted to change the files to text files we wanted to add .txt to the end of the files so we used this code: “dir | rename-item -NewName {$_.name -replace ".txt",""}”. Now we have two different Excels with as many measured values as one has acquired. When we measured the rotor, we made 10 steps. This means we must combine 10 impedance Excel values with 10 rotor and angle Excel values. For making this as easy as possible we created an Excel macro that automatically sorts, removes all unnecessary info, calculates the impedance values at each step, opens and combines the distance and angle Excel file, and lastly with the time step values combines the values of both measured files, the Excel macro DoAllProbe() can be found in Appendix II. When running the macro an impedance Excel file will open, check which impedance measurement file opens, then excel will ask which document you want to combine, choose accordingly to the opened document, for example, if impedance_measurement_1 is opened you choose rotor_angle_measurement_1. The macro might ask for the document up to three times. The macro will take care of the rest with you choosing the right documents when the macro asks. Note that to clocks of both computers must be in exact synch for this to work as smoothly as possible. The Excel files should look like Table 2. For better and cleaner result management and for visualizing the acquired results macro Graph() found in Appendix III and can be seen in Table 3.

Table 2: Results after DoAllProbe() macro.

Table 3: Results after Graph() macro.

5.4. Measuring We made the measurements in the electromechanics laboratory. We recorded voltage, current and position of the probe all the time. We used two Agilent Technologies 34410A measurement devices, the other measured current and the other voltage. We ended up to use 0.8 ampere AC current to produce the flux. With 0.8 amps current, a voltage was also around 0.8 volts, which means, that the total impedance of the winding and rotor was around 1 ohm. A Position of the probe, we recorded with distance and angle encoder. Position data we transferred to the computer via Arduino. Chapters Combining results with Excel and Arduino and sensors discusses more deeply how the data was taken to the computer and turned to readable figures.

Result Angle Distance0.991313 0 100.989059 1 10

Time Time_stamp Voltage Current CalculationResult Angle DistanceMon 14/May/2018 10:12:20 0.425231481 0.821145 0.814011 B / A 0.991313 0 10Mon 14/May/2018 10:12:21 0.425243056 0.82323 0.814223 B / A 0.989059 1 10

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Actual measurements were done by supplying power to the winding of the probe. While measuring current, voltage, distance and angle one team member rotated rotor slowly. This is how we got the most accurate results. Future improvement is servomotor to the axle of the rotor and also probe could be moved automatically. The most important in the actual measuring was to ensure that the air gap between probe and rotor is constant. We used 0.4 mm air gap, which ensures a margin for preventing contact and to provide the best measuring results. Air gap was inspected with feeler as can be seen from Figure 12.

Figure 12: Checking the air gap with feeler.

5.5. Measured impedances We measured current and voltage with Agilent 34410, which provide us 9.5 digits when we took results to the computer. In the datasheet of Agilent 34410, it is said that basic accuracy is 0.06%, which does not disturb our measurement. According to simulations, 5th decimal digit should change if there is porosity in the rotor. According to our measurement there was a change in 3rd decimal if the bar rotor bar were broken. In our rotor there was two broken bars. Broken bars were done by drilling holes through the rotor bars. Figure 13: Broken bars. Figure 14 shows the measured impedance values with aspect to the rotor angle measured with angle encoders. One can clearly see two big spikes in the impedance over the broken rotor bars were the drilled holes were, i.e. the measured results vary between a known broken rotor bar and healthy parts of the rotor. With the angle and distance encoder, the position can be pinpointed with almost a millimeter accuracy. The values between 46-77° is most probably porosity in the rotors bars. For even better measurements results one should repeat multiple impedance measurements over the area.

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Figure 14: Measured impedance over broken bars.

6. Reflection of the Project At the beginning of the project, all members had only a limited amount of knowledge about rotors and die-casting process. All members had done smaller projects during other courses, but this big project was first for everyone. Project plan, business aspects and final gala were all new things for us although we have participated in projects earlier. We all have also learned a lot about project management and scheduling.

6.1. Reaching objective The biggest objective of the project was, that we want to detect broken rotor bar with our measurement device. So clearly biggest success was, that we were able to detect broken rotor bar. Also, we were able to build such a stand, which makes rotor switching easy. The stand is solid and keeps the distance between probe and rotor constant. Communication between students and instructor was a success. In both directions, we got an answer either via WhatsApp-group chat or mail in a reasonable time.

6.2. Timetable In the Project plan we have detailed schedule. According to that schedule, our milestone “detect deviation in a predetermined faulty rotor” was felt behind schedule. This was a result of estimation for cutting the sheets. It was estimated, that it will take from one to two weeks to cut the sheets for the probe, but it took five weeks. Cutting service was bought outside Aalto University. Milestones helped us to follow the schedule. Luckily we were able to build the stand for the rotor, while sheets were in the cutting.

6.3. Risk analysis In the Project plan there is risk analysis, which says, that we have a minor probability for cutting takes more time than expected. Still, this risk took place (it took 5 weeks instead 1-2 weeks) and we made actions to continue without sheets. We started to do stand for rotor and probe before we had the probe.

0,979

0,98

0,981

0,982

0,983

0,984

0,985

0,986

0,987

0 15 31 46 62 77 93 108

123

139

154

170

185

201

216

231

247

262

278

293

309

324

339

355

Impe

danc

e (Ω

)

Rotor rotation (°)

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It was not ideal situation to build stand without the probe, because we had to estimate how we can assembly probe under the rotor. Impact of this risk was marked to be moderate, but we still managed to be in acceptable schedule thanks to our actions. Another risk was, that the probe does not fit to the rotor desired way. Luckily we had made perfect CAD model and the cutting was made accurately according to our model, so the probe fitted to the rotor. This risk was ranked to be minimal probability, but with significant impact. Now after project, we can say, that risk analysis held quite well and preparation for different kind of risks is recommended.

6.4. Project Meetings Project meetings were held about the times a week with a few exceptions (exam week etc.). The instructor was present in almost every other meeting. In the beginning when we were working with the simulation part (deeply explained in chapter Simulations in FEMM) we had to meet the instructor more often because we did not know how to handle the simulation with a new program. After the simulation model was done the actual physical work had to begin. After a few meetings with the instructor and by ourselves designing the stand for the rotor we met in the electromechanics laboratory in Otakaari 5. Slowly but surely the stand started to rise out of all sorts of different materials. The meetings turned into physical work for a few months. Because of the importunateness of the accuracy of the stand the meetings were mostly focused on building it. Once a month we still held a normal meeting to keep track of the work done and the work that we will have to do in the following weeks. We always tried to meet in a meeting room with the possibility to mirrors one’s computer to a larger TV screen. This way everybody had an easy way to follow the agenda of the meeting. The default agenda (as written in Appendix IV) was followed in almost every meeting. The memos of the project meetings were stored in Google drive with the rest of the files and folders needed for the project.

Default agenda for each Project Meeting: - Decide who writes the memo - Check, what we agreed to do before this meeting - Check, what each has accomplished - Check, if we are on schedule and if not how to fix it. - Agreeing on what each person is going to do by the next meeting - Agreeing on the next meeting time As a group, we were happy with the way we conducted our meetings. The most important thing that we discussed and decided in our meetings was what everybody should do until the next meeting. This way everybody knew right away after the meeting what is to be done this week. This way one can plan his week according to the workload. In our project we rarely had to do things on our one since we basically had only one working area, working on the stand and probe. Every now and then we could work remotely, for example when tweaking the Arduino codes and Excel macros. With the project meetings, we learned that everybody should have a specific work task that they should complete according to a deadline. If the group decides that this should be done without assigning the task to a specific person it is hard for the group to know who, how and when it should be done. We think we managed to solve both the project meetings and the physical work both according to the project plan and according to our expectations.

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6.5. Quality management In the Project plan, we determined how to manage the quality of different phases of this project. First, we determined that the quality of different project phases is determined before we start to do that phase. The quality of each phase is determined by our instructor and then we defined how to get to this quality. In the quality management, the responsibility of the project manager is to monitor, are we on the schedule and is the predefined quality achieved. Also, we discussed in our weekly meetings what we need to do to reach the quality what the instructors are defined. And of course, we asked frequently our instructor come and check what we have done and comment what is good and what needs to be improved. During this project, we managed to reach all our quality requirements and we followed the Quality management plan very well. However, we had small problems with the stand because the distance between the probe and the rotor must be constant whole time and it also must be very short that the measurements can be done. We managed to handle this challenge by doing adjustable stand which allows setting the probe right position in relation to the rotor. Also, some challenges came up with the measurements when we tried to measure values in a certain point. The results vary too much between different measurements and even when we do measurements on the same point the difference between these results was too big. Better measurement results we got when we rotated rotor at the same time when we did measurements. In this way, we managed got the measurement results where we can see the broken bars and porosity.

7. Discussion and Conclusions The main objective of the project was to analyze the impedance of rotor bars at different positions by injecting flux via a probe. To achieve this, we have gone through some phases as; simulation phase, the design of the setup, and test of the setup. In simulation phase, FEMM has been used, and reasonable simulation results have been found which would be beneficial for real design for the other phases. Besides learning how to make modelling in FEMM, we have also learnt how FEMM operates. After logical simulation results, the design of the setup has been made. During this phase, we have become more familiar with the use of mechanical devices, and more talented to use those devices for several purposes. After that phase, the setup has been tested. The testing has been done by using a power supply, measurement devices, Arduino, distance sensor, encoder and a computer. Using the power supply, the flux is injected into the rotor bars, and the voltage, current measurements are taken to the computer. By these measurements, the impedance can be found. Also, distance and rotation data is taken via Arduino as the rotor rotates. All those data are combined in an Excel Sheet. Results show us that when there is a broken bar, impedance increases dramatically. On the other hand, the increase in case of porosity is not as dramatic as the other case. But still, there is a slight increase compared to normal range. We can say that our product is well applicable to detect broken bars; however, it can be improved for the detection of porosity. During the project process, besides the theoretical experience that we got, working as a group has developed our both communication and management skills.

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List of Appendixes

Appendix I: Arduino code

Appendix II: DoAllProbe() Excel macro

Appendix III: Graph() Excel macro

Appendix IV: Project plan

Appendix V: Business aspects document

References [1] Lecture Slides of Electromechanics Course of Aalto University

[2] ”Quality Assurance Testing for Screening Defective Aluminum Die-cast Rotors of Squirrel

Cage Induction Machines, 2017 IEEE”

[3] http://forum.arduino.cc/index.php?topic=437398.msg3251256#msg3251256, Accessed

18.5.2018

Appendix I Page 1 of 2

Appendix I: Arduino code 1. #include "Adafruit_VL53L0X.h" 2. const int buttonPin = 2; 3. int buttonState = 1; 4. int lastButtonState = 1; 5. int a=0; 6. int mitattu=0; 7. Adafruit_VL53L0X lox = Adafruit_VL53L0X(); 8. 9. //Pins of decoder 10. const int CSn = 4; // Chip select 11. const int CLK = 7; // Clock signal 12. const int DO = 8; // Digital Output from the encoder which delivers me a 0 or 1, depending

on the bar angle.. 13. 14. unsigned int sensorWaarde = 0; 15. 16. 17. void setup() { 18. Serial.begin(115200); 19. pinMode(buttonPin, INPUT_PULLUP); 20. 21. //decoder 22. pinMode(CSn, OUTPUT); 23. pinMode(CLK, OUTPUT); 24. pinMode(DO, INPUT); 25. 26. //Let's start here 27. digitalWrite(CLK, HIGH); 28. digitalWrite(CSn, HIGH); 29. 30. // wait until serial port opens for native USB devices 31. while (! Serial) { 32. delay(1); 33. } 34. 35. if (!lox.begin()) { 36. Serial.println(F("Failed to boot VL53L0X")); 37. while(1); 38. } 39. Serial.println("LABEL,Date,Time,Timer,Distance(mm),Angle(deg)"); 40. } 41. 42. 43. void loop() { 44. buttonState = digitalRead(buttonPin); 45. VL53L0X_RangingMeasurementData_t measure; 46. sensorWaarde = readSensor(); 47. lox.rangingTest(&measure, false); // pass in 'true' to get debug data printout! 48. 49. if (buttonState == a){ 50. if (measure.RangeStatus != 4) { // phase failures have incorrect data 51. Serial.print("DATA,DATE,TIME,TIMER,"); 52. Serial.print(measure.RangeMilliMeter); 53. Serial.print(","); 54. Serial.println(((float)sensorWaarde/1024)*360); 55. } 56. 57. else { 58. Serial.print("DATA,DATE,TIME,TIMER,"); 59. Serial.print("out"); 60. } 61. a = 1; 62. mitattu = 1; 63. delay(500);

Appendix I Page 2 of 2

64. buttonState = digitalRead(buttonPin); 65. 66. if (mitattu=1 && buttonState==0){ 67. delay(1000); 68. a=0; 69. } 70. } 71. } 72. 73. 74. //Code of decoder 75. 76. unsigned int readSensor(){ 77. unsigned int dataOut = 0; 78. 79. digitalWrite(CSn, LOW); 80. delayMicroseconds(1); //Waiting for Tclkfe 81. 82. //Passing 10 times, from 0 to 9 83. for(int x=0; x<10; x++){ 84. digitalWrite(CLK, LOW); 85. delayMicroseconds(1); //Tclk/2 86. digitalWrite(CLK, HIGH); 87. delayMicroseconds(1); //Tdo valid, like Tclk/2 88. dataOut = (dataOut << 1) | digitalRead(DO); //shift all the entering data to the left

and past the pin state to it. 1e bit is MSB 89. } 90. 91. digitalWrite(CSn, HIGH); //deselects the encoder from reading 92. //Serial.println(((float)dataOut/1024)*360); 93. return dataOut; 94. 95. }

Appendix II Page 1 of 2

Appendix II: DoAllProbe() Excel macro

Sub Probe() Columns("A:A").Select Selection.TextToColumns Destination:=Range("A1"), DataType:=xlDelimited, _ TextQualifier:=xlDoubleQuote, ConsecutiveDelimiter:=False, Tab:=False, _ Semicolon:=False, Comma:=False, Space:=False, Other:=True, OtherChar _ :=";", FieldInfo:=Array(Array(1, 1), Array(2, 1), Array(3, 1), Array(4, 1), Array(5, _ 1), Array(6, 1), Array(7, 1)), TrailingMinusNumbers:=True Range("L9").Select ActiveCell.FormulaR1C1 = "V" Range("M9").Select ActiveCell.FormulaR1C1 = "=AVERAGE(RC[-9]:R[214]C[-9])" Range("M10").Select ActiveWindow.SmallScroll Down:=-6 Range("M9").Select Selection.Copy Range("M10").Select ActiveSheet.Paste Range("M10").Select Application.CutCopyMode = False ActiveCell.FormulaR1C1 = "=AVERAGE(R[-1]C[-10]:R[213]C[-10])" Range("M10").Select Selection.Copy Range("M11").Select ActiveSheet.Paste Range("M11").Select Application.CutCopyMode = False ActiveCell.FormulaR1C1 = "=AVERAGE(R[-2]C[-7]:R[212]C[-7])" Range("L10").Select ActiveCell.FormulaR1C1 = "I" Range("L11").Select ActiveCell.FormulaR1C1 = "R" Range("L12").Select ActiveCell.FormulaR1C1 = "Calc R" Range("M12").Select Application.CutCopyMode = False ActiveCell.FormulaR1C1 = "=R[-3]C/R[-2]C" Range("A1:G6").Select Selection.ClearContents Columns("B:B").Select Selection.ClearContents Range("B9").Select ActiveCell.FormulaR1C1 = "=TIMEVALUE(RIGHT(RC[-1],8))" Range("B9").Select Columns("B:B").EntireColumn.AutoFit Range("B9").Select Selection.AutoFill Destination:=Range("B9:B104"), Type:=xlFillDefault Range("B9:B104").Select ActiveWindow.SmallScroll Down:=-168 Columns("G:G").Select Selection.ClearContents Range("G8").Select ActiveCell.FormulaR1C1 = "Angle" Range("H8").Select ActiveCell.FormulaR1C1 = "Distance" Range("G9").Select ActiveCell.FormulaR1C1 = _ "=INDEX('Simple Data'!R[-7]C[-2]:R[900]C[-2],MATCH(RC[-5],'Simple Data'!R[-7]C[-5]:R[900]C[-5],0))"

Appendix II Page 2 of 2

Range("H9").Select ActiveCell.FormulaR1C1 = _ "=INDEX('Simple Data'!R[-7]C[-4]:R[900]C[-4],MATCH(RC[-6],'Simple Data'!R[-7]C[-6]:R[900]C[-6],0))" Range("G9:H9").Select Selection.AutoFill Destination:=Range("G9:H999"), Type:=xlFillDefault Range("G9:H999").Select End Sub Sub DoAllProbe() Dim file Dim path As String path = ActiveWorkbook.path & "\" file = Dir(path & "*.txt") Do While file <> "" Workbooks.Open Filename:=path & file Call Probe ActiveWorkbook.Save ActiveWorkbook.Close ' set file to next in Dir file = Dir() Loop End Sub

Appendix III Page 1 of 1

Appendix III: Graph() Excel macro Sub Graph() Range("F:F,G:G").Select Range("G1").Activate Selection.Copy Sheets.Add After:=ActiveSheet ActiveSheet.Paste ActiveSheet.Shapes.AddChart2(227, xlLine).Select ActiveChart.SetSourceData Source:=Range("Taul1!$A:$B") ActiveSheet.Shapes("Kaavio 1").IncrementLeft -199.5 ActiveSheet.Shapes("Kaavio 1").IncrementTop -24.75 Application.CutCopyMode = False Application.CutCopyMode = False Application.CutCopyMode = False Application.CutCopyMode = False Application.CutCopyMode = False ActiveChart.FullSeriesCollection(1).Delete ActiveChart.SeriesCollection.NewSeries ActiveChart.FullSeriesCollection(1).Name = "=Taul1!$A$1" ActiveChart.FullSeriesCollection(1).Values = "=Taul1!$A$2:$A$102" ActiveChart.FullSeriesCollection(1).XValues = "=Taul1!$B$2:$B$99" ActiveWindow.SmallScroll Down:=-261 Range("C2").Select ActiveCell.FormulaR1C1 = "=AVERAGE('1_measuyrement'!RC[5]:R[222]C[5])" Range("C1").Select ActiveCell.FormulaR1C1 = "Distance" Range("C2").Select Selection.Copy Range("C3").Select Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _ :=False, Transpose:=False Application.CutCopyMode = False Selection.AutoFill Destination:=Range("C3:C188"), Type:=xlFillDefault Range("C3:C188").Select Range("I179").Select ActiveWindow.SmallScroll Down:=-132 End Sub

Appendix IV Page 1 of 14

Appendix IV: Project plan Aalto University ELEC-E8004 Project work course Year 2018

Project plan

Project #28 Diagnosis tool for cage induction machine rotor

Date: 29.1.2018

Jouni Lahtinen Mark Nortamo Jani Sormunen



Information page Students Jouni Lahtinen Mark Nortamo Jani Sormunen İsmet Tuna Gürbüz Project manager Jouni Lahtinen Official Instructor Aswin Balasubramanian Starting date 4.1.2018 Approval The Instructor has accepted the final version of this document Date: 28.1.2018


1) Background Induction motors are used all over the world over a wide range of applications. The most commonly used motors are squirrel cage induction motors. There are mainly two types of bars used in squirrel cage rotors - copper bars and aluminum die-cast bars. The aluminum die-cast rotors are used widely in large scale industrial production in order to reduce the manufacturing costs. The die-casting process of Aluminum leads to varied levels of porosity in the rotor bars. Higher levels of porosity tends to increase the resistance of the rotor resulting in degradation of motor performances and at times causing irreversible damages. In this project, our aim is to design flux injection device which will be used to detect varying levels of porosity. The main core behind this device is to analyze the rotor impedance which will enable us to have an insight on the level porosity. By using this device, we will also be able to monitor the defects caused in manufacturing process such as a broken bar in the rotor slot. The design of the flux injection device begins with the 2D finite element simulation of the rotor-flux injection device assembly. A final prototype will be made by analyzing the simulation results of different designs on the rotor model, which will be tested on the rotors with real time fault scenario. From the perspective of Business Aspect, there are so many companies ranging from EV startups to Elevator super-giants which manufacture squirrel cage induction machines in large scale looking for a good Quality assurance procedures and devices. The success of this project and device will definitely attract huge companies which are drastically investing on novel and innovative Quality Assurance methods.

2) Expected output The expected output of the project is a completed design of the flux injection device to analyze the resistance of the rotor.

- It will enable us to find the fault locations by analyzing the resistance or impedance map of the rotor. Higher levels of porosity is indicated by higher resistance which will be more than the nominal value.

- Expected user of the device are companies which manufacture squirrel cage induction machines in large scale looking for a good Quality assurance procedures and devices.

- From customer perspective (Process Industries), this device will help in identifying the rotors with higher porosity level or a broken bar, which helps them in phasing-out low performance rotors.

- The device is very simple to use for technicians having basic knowledge in electro mechanics. - It is expected that the performance of the device is to sense small change in impedance level

and to analyze it correctly to identify if the changes are due to porosity or a broken bar. - The flux injection device, its fault detection analysis and interpretation of the result from this

analysis will be demonstrated in the end of the project. The expected design of the flux injection probe is shown in the Figure 1;


Figure 1: Expected Design (Retrieved from “Quality Assurance Testing for Screening Defective

Aluminum Die-cast Rotors of Squirrel Cage Induction Machines, 2017 IEEE”)

3) Phases of project Below is listed the phases of the project with corresponding estimates of workload and deadlines:

1. Project plan (DL 29.1.2018) - Workload 4 weeks

2. Simulation of the Diagnostics tool using FEMM 4.2 (DL 07.02.2018) - Workload 1 week

3. Designing a real-time prototype of the Diagnostic tool (DL 15.03.2018) - Workload 3-6 weeks

4. Testing and tweaking the Diagnostics tool (DL 15.04.2018) - Workload 3-6 weeks

5. Making the final report (DL 30.04.2018) - Workload 3-6 weeks

Milestones: M1: Complete Project Plan M2: Make a working simulation with the actual specifications of the model M3: Complete Business Aspects M4: Completed Diagnostics tool setup M5: Detecting deviation in a predetermined faulty rotor M6: Verification and Testing of the Diagnostics tool setup M7: Submitting Final Report


4) Work breakdown structure (WBS)

Figure 2: Work breakdown structure

5) Work packages and Tasks of the project and Schedule

5.1) Work packages and tasks Work Package 1 - Project plan (150 h) - Manager: Jouni

Task 1.1: Get to know the topic (50 h)

- Get familiar with the article given by instructor. - Talk about project with other group members and instructor.

Task 1.2: Write a project plan (100 h)

- Elect project manager. - Choose work places and tool (writing and construction). - Define phases of the project, schedule and expected output.

WP 2 - Simulation (50 h) - Manager: Mark

Task 2.1: Get to know FEMM 4.2 (10 h)

- Download FEMM to own computer.

- Watch tutorials and get familiar to the program.

Task 2.2: Design the model of the rotor (15 h)

- Measure the rotor dimensions.

- Clarify rotor materials.

- Model rotor with FEMM 4.2

Task 2.3: Design the model of the flux injection probe (15 h)

- Decide dimensions of the probe.


- Decide air gap between rotor and the probe.

- Design the coil: coil wire thickness and material, number of turns in the coil.

- Model designed flux injection probe to the same file with rotor.

Task 2.4: Simulate (10 h)

- Try to find out what is the best parameters to detect porosity (feeding voltage and frequency).

- Simulate different kind of broken rotors (broken bar, less/more porosity, unbroken).

WP 3 - Design and build the setup (250 h) - Manager: Ismet Task 3.1: Probe (100 h)

- Send steel sheets for cutting. - Winding the coil and stacking the steel sheets together.

Task 3.2: Stand (50 h) - Make a strong solid stand for the rotor. - Modular and flexible stand that allows changing the rotor samples

Task 3.3: Sensors (50 h) - Choose distance and rotation angle sensors. - Implement sensors to the stand and connect them to the mainboard (Arduino). - Figure out - if is it possible (limited resources) to get measurements straight to computer.

Task 3.4: Table (20 h) - Choose a solid and strong enough table for stand.

Task 3.5: Power supply (30 h) - Go through safety issues. - Choose a power supply. - Make necessary connection for the test setup.

WP 4 - Business aspects (75 h) Manager: Jani

Task 4.1: Business aspects seminar (25 h) - Prepare presentation slides for the seminar.

Task 4.2: Business aspects document (50 h) - Write business aspects document.

WP 5 - Testing and tweaking the setup (200 h) Manager: Mark Task 5.1: Testing (150 h)

- Confirm that measurement data that comes to the computer (if direct connection). - Make sure that air gap length is always constant. - Try to find out what is the best parameters to detect porosity (feeding voltage and

frequency). - Simulate different kind of broken rotors (broken bar, less/more porosity, unbroken).

Task 5.2: Compare the testing results to the simulation results (50 h) - Compare different simulations to real tested ones.


- If results are not satisfying, it is recommended to test again with different parameters (voltage and frequency).

WP 6 - Making the report (100 h) Manager: Jouni Task 6.1: Documentation throughout the project (50 h)

- Take pictures, save simulation files, results and follow the budget. - The more we do documentation throughout the project the easier it is to write the final

report. Task 6.2: Write the final report (50 h)

- Final report is meant to explain whole project from learning objectives to the final product. WP 7 - Final gala (75 h) Manager: Jani Task 7.1: Design the presentation stand (20 h)

- Make a poster from our project. - Make a video, if it is not safe to demonstrate our project in the TUAS lobby.

Task 7.2: Preparations for gala (15 h) - Prepare to be able to answer to questions related to our project. - Appoint what we are going to bring to the gala.

Task 7.3: Participation in the final gala (40 h) - Exhibit our project in the final gala.


5.2) Tasks Table 1: Estimated working hours for each task.

5.3) Detailed schedule Detailed schedule is presented in Appendix A.

Work package

Task Estimated working hours

WP 1 1.1 50 1.2 100 WP 2 2.1 10 2.2 15 2.3 15 2.4 10 WP 3 3.1 100 3.2 50 3.3 50 3.4 20 3.5 30 WP 4 4.1 25 4.2 50 WP 5 5.1 150 5.2 50 WP 6 6.1 50 6.2 50 WP 7 7.1 20 7.2 15 7.3 40 Total 900h


6) Work resources

6.1) Personal availability during the project Table 2. Number of hours available for the project (excluding lectures and seminars) per week.

Jouni Lahtinen

Mark Nortamo

Jani Sormunen


Week 1 4 4 2 4 Week 2 10 8 10 10 Week 3 12 12 12 12 Week 4 10 14 14 12 Week 5 10 14 14 12 Week 6 8 20 14 12 Week 7 2 4 2 0 Week 8 12 10 14 13 Week 9 12 20 13 13

Week 10 6 20 13 12 Week 11 10 20 13 13 Week 12 10 6 13 13 Week 13 10 4 13 15 Week 14 0 0 0 0 Week 15 20 0 13 14 Week 16 20 12 13 14 Week 17 20 13 13 14 Week 18 20 4 13 14 Week 19 18 20 13 14 Week 20 12 20 13 14 Week 21 0 0 0 0

Total 225 225 225 225

6.2) Personal goals Jouni: I would like to learn the basics of FEMM simulation program. I am looking forward to see, if we succeed in simulating our measuring probe and then put it in practice. My personal goal is to improve my oral and written English skills. Of course, it is also beneficial to learn project management skills like scheduling and project planning (WBS etc.). İsmet: My main goal is to have an experience on real team project and to improve my both communication and social skills. The time management, risk analysis skills etc., will contribute to my future professional career. Technically, I would like to learn basics of Finite Element Analysis and the use of FEMM simulation program. Jani: One of my personal goals is to build a device that detects porosity of the rotor. During this project, I would also like to learn project management skills such as scheduling and project planning. I also want to improve my English writing and oral skills.


Mark: I would like to learn basics in simulating finite elements and then actually building the created simulation model. I would also like to learn how to work in a project group; communication, writing together and overall working in a multicultural project group. I would also like to improve my language skills in English, both written and spoken language.

7) Cost plan and materials Budget for this project is 1000 €. The budget is handled by the instructor and it is expected that he takes care of purchase of the materials. The materials in need are selected and approved in our project meetings, after that the project manager sends the details of the materials to the instructor and if the instructor approves these materials are ordered.

Table 3: Foreseen costs listed.

Item/service Estimated cost

Cutting of the steel sheets 400-500 €

Rotary encoder ~20 €

Distance sensor ~10 €

Arduino ~20 €

It looks like we have some extra money, but there can be some unexpected expenses, such as breakdowns or the need for a new item, so the margin in the budget is good.

8) Other resources Group meetings are organized either at electro mechanics laboratory or at rooms that can be reserved via Aalto Space application. Most of the time we work at electro mechanics laboratory (Otakaari 5L). It is assumed that we do not need keys to laboratory, because there is always someone from 8 am to 4 pm. In the laboratory, we have tools that we will need, for example screwdrivers, multimeters and oscilloscopes. In electro mechanics laboratory, there are steel sheet materials and power supply which we need for our project. We can also store our project parts like rotor, rotor rack and measurement device in electro mechanics laboratory. Before we use dangerous tools like power supply our instructor will show us how to use it safely.

Our first step in this project is to do simulation model. We use FEMM 4.2 open-source software to do the simulation model. We all install FEMM to our own laptops, so we do not need to borrow computer from laboratory.


9) Project management and responsibilities

- Responsibilities of project manager are; o To check the deadlines and make an appropriate plan for the deadlines.

o To prepare the agenda for the meetings.

o To check the process of each work packages to see how they are compared to project plan made.

- Responsibilities of instructor are; o To guide the project group about phases.

o To show the basic parts of each phase (as basics of simulation program, main principle of diagnostics tool etc.).

o To check the main phases and see the process according to project plan made.

o To help the group while buying something.

- Responsibilities of Work Package leaders are; o To take care of Working Package Schedule.

o To contact the instructor in case of any problem in that Work Package.

o To find alternative solutions to possible risks in the Work Package.

10) Project Meetings We hold project meetings once a week, which is also accompanied by our instructor. We also try to meet again for the second time during the same week so that the instructor is not involved. Meetings start quarter past the hour. Default agenda for each Project Meeting:

- Decide who writes the memo - Check, what we agreed to do before this meeting - Check, what each has accomplished - Check, if we are on schedule and if not how to fix it. - Agreeing on what each person is going to do by the next meeting - Agreeing on the next meeting time - The project manager prepares the agenda for meetings and shares it with all the participants.

Memo template: - Decisions, what was done in the meeting - Tasks, what each person is going to do by the next meeting - The time of the next meeting - Memos are stored in the project's Google Drive folder.


11) Communication plan As described in Chapter 10 we are striving for weekly face-to-face meetings with the instructor. As a group, we decide the next meeting time with the instructor either face-to-face on our weekly meetings or via the created WhatsApp group in which the instructor is also present. The instructor has agreed to join our WhatsApp group. Additionally, to the meeting where the instructor is present we are also meeting one extra time without the instructor. This internal meeting can be either before or after the meeting with the instructor depending on the agenda. Besides the WhatsApp group where the instructor is present, the group also has a private group chat where we can communicate more freely without forcing the instructor to be a part of every conversation. Besides the above-mentioned communication plans the group also uses email when necessary. Google Docs built in comment and chatting functions will also be a big part of the groups communication plan.

12) Risks Table 4: Risks along with severity, probability and actions. Scale: Minimal-Minor-Moderate-Significant-Severe

Risk Severity Actions

Simulation part takes more time than expected.

Minor (moderate probability but low/minor impact).

We try to get project ready about week before deadline, so we can work few days before schedule.

Sheets of motor core laminations cutting takes more time than expected.

Minor (minor probability and moderate impact)

We have to confirm as soon as possible how long does it takes

to cut needed steel sheets.

Probe does not fit to rotor desired way (about 1mm

thickness).

Moderate (minimal probability but significant impact)

Either we have to send new cad-file and steel sheets to cutting or we can try to do minor chances

to one we have.

13) Quality plan Quality criteria must be set for the different phases of the project. When these criteria are fulfilled, it can be assumed that the project quality is good. The project manager is responsible on the quality of each work package and monitors it by comparing its current results with quality criteria that we have defined. The role of the instructor is to define what kind of quality our project should produce. In our weekly meetings, we can discuss about quality problems and consider how we are going to improve the quality.


14) Changing this plan We make this plan as an individual work and in group meetings we go through all the material which we have added since last meeting. All the changes are visible to everyone (group + instructor) all the time, because this document is shared via Google Drive. Before we have decided that this project plan is complete, we ask for instructor to approve this document. If we have to do changes to this project plan (example some phase needs more time) before instructor has approved it, we do changes in group meeting with instructor. If someone is missing the group meeting, he can see the changes in Google Drive. We can highlight changes and rename the document like ProjectPlan_Rev1.

15) Measures for successful project Students: The project is deemed successful when simulation gives us the expected results and the simulation model dimensions should be a copy of the real-life rotor. The simulation model should detect a faulty rotor when a faulty rotor is simulated. The real-life built model should be dimensioned and built as the working simulation model. The built model should also be able detect the faults and porosity in the rotor when porosities are present. The documentation of the project will be an ongoing process, i.e. documentation of how and when the milestones and the expected quality of the model is reached. The project is successful if we as a group achieve the expected outputs and deliver an outstanding final report and presentation in the final gala. Instructor: The project is successful according to the instructor if we achieve the personal and project group goals and milestones. The simulation should get proper results and work as expected when designing the real-life model. The simulation model should be a proper setup that could be used in the future for other works which is related to rotors. The project is successful if the built setup work as the simulation model and is thereby able to detect the porosity and faults in the rotor. The built model should deliver proper and useful testing results.


WP 1

Get to know

the topic (50h)W

rite a project plan (100h)W

P 2G

et to know FEM

M 4.2 (10h)

Design the m

odel of the rotor (15h)D

esign the model of the flux injection probe (15h)

Simulate (10h)

WP 3

Probe (100h)Stand (50h)Sensors (50h)Table (20h)Pow

er supply (30h)W

P 4Business aspects sem

inar (25h)Business aspects docum

ent (50h)W

P 5Testing (150h)C

ompare the testing results to the sim

ulation results (50h)W

P 6W

rite the final report (50h)D

ocumentation throughout the project (50h)

WP 7

Design the presentation stand (20h)

Preparations for gala (15h)Participation in the final gala (40h)W

eek Num

ber1

23

45

67

89

1011

1213

1415

1617

1819

2021

22D

ate1.-7.1

8.-14.115.-21.1

22.-28.129.1-4.2.

5.-11.212.-18.2

19.-25.226.2.-4.3

5.-11.312.3-18.3

19.-25.326.3-1.4

2.-8.49.-15.4

16.-22.423.-29.4

30.4-6.5.7.-13.5.

14.-20.521.-27.5

28.5-3.6W

orking hours40

6060

4060

6052,5

47,555

5050

5060

4025

2520

1540

M1

M2

M3

M4

M5

M6

M7

Work

PackageTask

Get to know the topic

Project plan DL 29.1.FEM

M

De. probeSim

ulateB. Probe

B. Stand

TablePow

. supp.

Sensor

De. rotor

TestingCom

pare results to

P. sta. DL 8.5.

B. as. sem. DL 2.3.

Gala

Final Report DL 28.5.

Prepara. gala

B. aspects document DL 9.3.

Documentation throughout the project

16) Appendix A

Appendix V Page 1 of 11

Appendix V: Business aspects document Aalto University ELEC-E8004 Project work course Year 2018

Business aspects

Project #28

Diagnosis tool for cage induction machine rotor

Date: 8.3.2018

Jouni Lahtinen Jani Sormunen Mark Nortamo



Information page

Students Jouni Lahtinen Jani Sormunen Mark Nortamo İsmet Tuna Gürbüz Project manager Jouni Lahtinen Official instructor Aswin Balasubramanian

Starting date 4.1.2018 Approval The instructor has accepted the final version of this document Date: 9.3.2018


Summary This document shows the business aspects of “Diagnosis Tool for Cage Induction Rotor” project. In this project, we are designing a flux injection device in order to detect the porosities and defects of rotor slots. There are plenty of companies from small startups to giant companies manufacturing squirrel cage induction machines in large-scale looking for good quality assurance procedures and devices. Our main business idea is to complete this project in a such a successful way that it can attract all the companies including the huge ones including ABB, Siemens, Toshiba. Millions of motors are sold all over the world every year. The aimed market for the product is all squirrel cage induction rotor manufacturers using aluminum die-cast rotors. There is no doubt that our product will enable them to both save their budget and manufacture products in a better quality. Our product can be used for all the squirrel cage induction motors having aluminum die-cast bars up to the rated power of 1000 kW. Customers will be willing to prefer our product because the use of the product is very simple and more sensitive measurements can be done compared to other devices. One of the most important criteria for us is the quality of the product in terms of accuracy, reliability, and sensitivity. Intellectual property is an important issue for this project. The code that is used to analyze the data coming to flux injection probe can be protected by copyright. As group members of this project, we are planning to protect the name of the product by trademark. Also, the designed product will meet the directives of 2013/35/EU and 2014/30/EU which are the criteria for marketing the product. The details of Business Idea, Product/Service, Market Situation and Competitors Analysis, Intellectual Property, Product Development and Technology, Conformance and SWOT-Analysis will be explained in this document.

1) Business idea Porosity in aluminum die-cast squirrel cage rotors could emerge during the die-cast filling process. Porosity in these bars leads to degradation in motor efficiency and performance. Our business product is a measuring device for determining if a rotor is faulty or not by measuring if during the filling of the aluminum in die-cast rotors porosity emerged. The product includes a preset flux injection device that is able to detect the varied levels of porosity and monitor the defects caused in the manufacturing process such as broken bars in rotor slots. Our potential customers are all the aluminum die-cast squirrel cage rotor manufacturers, this means that the biggest individual customers are companies like ABB, Toshiba, Siemens, and WEG. When predetermining if the rotor is faulty or not before shipping and installing it onsite the customer can save a lot of money. When discarding a faulty rotor directly rather than using a faulty rotor that will increase the power losses and in operation maintenance costs, the cost per motor and costs of motors in use will naturally decrease. The benefits of our product are compared to other available products is that we can pinpoint the faulty part very accurately meaning that manufacturing companies can with this information redesign their manufacturing process if there is a correlation in the creation of porosity. Everybody wants to make as efficient and as high-quality products as possible. The rotor manufacturing companies know how to make rotors and we know how to check the quality of their end product meaning that we are not competing with them, rather helping them surviving on the market even better. Our customers will stand out from the rest of the rotor manufacturers because they will never sell anything but 100% perfectly healthy rotors with our perfect product.


2) Product/service There is no doubt that energy is one of the most important essential needs of mankind. It is not possible to think about any part of our life without energy. 22% of this energy is used in the form of electricity and 40% of electricity is used by electric motors. There is a wide range of usage of electric motors from our small household equipment to the big devices in the factory. Among all types of motors, induction motors are the most needed ones. Induction motors are used all over the world with a wide range of applications. The most common used induction motors are squirrel cage induction motors. There are mainly two types of rotors used in squirrel cage induction motors as copper rotors and aluminum die-cast rotors. Copper rotor bars are the mainly used ones in these machines. However, recently, aluminum die- cast rotors have become more popular for the manufacturers more than copper rotors to drop manufacturing cost to compete in global market. As it is known, for the same amount of aluminum and copper, aluminum is much cheaper; therefore, it is considered to be a good idea to use aluminum for economical reasons. This can decrease the costs up to 20%. Porosity in aluminum die-cast squirrel cage rotors is inevitably introduced during the die-cast process. Porosity may lead to degradation in motor performance and outages causing irreversible damages. There are plenty of ongoing tests to measure the quality of rotor; however, the results of these tests have shown that they are not sufficient enough to have sensitive data. In this project, we are designing a flux injection device in order to detect the varied levels of porosity and monitor the defects caused in the manufacturing process such as broken bars in rotor slots. The expected output of the project can be illustrated as follows;

Figure 1: Expected Design (Retrieved from “Quality Assurance Testing for Screening Defective Aluminum Die-cast Rotors of Squirrel Cage Induction Machines, 2017 IEEE”) The flux injection device is made up of U-shaped ferromagnetic core and excitation windings to generate magnetomotive force to be used in flux injection. As the rotor rotates with a low speed, the designed probe injects flux to the rotor bars. This flux injection device is used for

3. Excitation of the bars and end rings with AC voltage applied


4. Monitoring the rotor by the voltage and current measurements in the coil The main core of our product is to analyze the rotor impedance. When the rotor bars are exposed to porosities, the equivalent rotor impedance increases. The equivalent circuit in case of porosity can be modeled as follows;

Figure 2: Equivalent Circuit of Device and Rotor Slots Under Excitation (Retrieved from “Quality Assurance Testing for Screening Defective Aluminum Die-cast Rotors of Squirrel Cage Induction Machines, 2017 IEEE”)

As can be seen from the figure, as the porosity increases, the equivalent resistance increases. By using this probe, the aim is to measure the impedance of each rotor slots. If the impedance is more than a specified range, it should be understood that there is porosity in that slot. The impedance measurements will give an insight into the porosity level according to the range of impedance value. The expected product will be suitable for whole squirrel cage induction machines having aluminum die-cast rotor bars.

3) Market situation and competitors analysis In 2010 over 15 million induction motors were sold in EU. This number does include all the induction motor types, but squirrel cage induction machines with aluminum die-cast rotors are the most common one. The recent trend is to replace fabricated copper rotors with aluminum die-cast rotors. [1] Reason for the trend is cost-effectiveness – fabricated copper rotors are more expensive to manufacture. Especially manufacturers who are switching from copper to aluminum are the most important customer group. They easily buy measurement devices to confirm their quality in the new production line. Biggest individual customers are companies like ABB, Toshiba, Siemens and WEG. Over 15 million induction motors sold in EU mean, that there have to be hundreds of manufacturers just for EU markets. [2] We can sell at least four probes for every customer because the probe is a model specific product. A rough estimation of sales is a hundred customers and five probes for each customer, it makes five hundred units. We can also make a profit by selling training courses where the customer learns how to get the most reliable measuring results and how to read the results. Desired market share is around 40% because some manufacturers want to use more accurate and way more expensive X-ray technique, let’s assume 15%. Cheaper and inaccurate weighing technique takes 20% and the rest (25%) does quality control only rarely with loaned devices. A customer always thinks the benefit of the investment. Our measurement device gives the shortest repayment period, because of the measuring quality and relatively low investment cost.


Actually, there are not lots of similar devices produced by other companies for the detection of porosity but we can state 3 of our competitors as follows; Schenck company produces devices for weighing the rotor. Aml Instruments company produces devices as porosity measurement instruments. Phynix company produces porosity detection devices for electrical systems Although the size of our competitors is not large, the restricted number of products is enabling for them to have a good amount of sales. Together with the success of our project, there is no doubt that market will change a lot. The most important competitive factor for our goals is the quality. Our aim is to produce a product which has further features than the previous competitors. Besides quality, a suitable, low price will be determined for our product. The biggest advantage of our product is being suitable to wide range of rotor dimensions.

4) Intellectual property In the article, "Quality Assurance Testing for Screening Defective Aluminum Die-cast Rotors of Squirrel Cage Induction Machines", Myung et al. introduced a method for detecting casting faults in aluminum die-cast rotors. Our product uses this method, so we can’t get patent to our product. There is another way to protect our intellectual property. The code, that is used to analyze the data we get from flux injection probe, can be protected by the copyright. Also, we need to protect name/label of our product, that nobody can use it wrongly. It can be protected by trademark. The expert knowledge, what we, project team members, get in this project is also intellectual property. This property should be protected by some contract between team members. In this way, nobody by alone can’t get financial benefit from the product which whole project team has been developing.

5) Product development and technology We have done a successful simulation with FEMM 4.2 simulation software. Results showed for us, that we can detect even small porosity in rotor bar if we have enough accurate voltage source, which measures current and voltage. Measuring resolution needs to be millivolts, which is not a problem for laboratory voltage source. After we have built our prototype, we have to do measurements to verify, what should be the resolution of voltage and current measuring in a commercial product. For a commercial product, we are buying voltage source from some other company. We have to measure also rotor angle and probe position. The position helps us to map how the porosity or broken bars are distributed in the rotor. Now we have ordered steel sheets for the probe, Arduino, angle - and position sensors. Our goal is to get data straight from sensors to a computer via Arduino. We hope, that we get first measurements done after few weeks. First real life measurements tell us a lot how far from commercial product our project remains. If everything goes well, it is possible to make a commercial product based on our project. We are not developing own measuring software, which should be made for a commercial product. In a commercial product at least results need to be transferred straight to .csv file and then used with specific Excel or Matlab script. Another problem is, that probe is rotor model specific product. This means, that if a customer wants to measure the different size of rotors, it has to buy probe for each


rotor model. Simulation is also necessary to do for a new kind of rotors to verify parameters such as current and voltage values for the probe. Rotor rack can be made for few rotors models, that have about the same dimension Significantly of a different size rotor models needs probably own racks. Also in our project, we move probe and rotate rotor by hand. This should be automated in the commercial version. A competitive technique to monitor the quality of rotor is performed by measuring the weight of the rotor. First before die-casting and then after die-casting. With this technique, it is possible to detect low filling factor, but you do not know how porosity is distributed and is there just porosity or totally broken bar. X-ray scanning other quality measuring tool, but it is way too expensive to scan all the rotors with X-ray. X-ray scanning is accurate, but because of the costs, it is only used for occasional quality monitoring. From the cost and accuracy perspective, our product is somewhere between weighing and X-ray techniques. Our project advantage is, that it does not cost too much and give enough accurate analysis of the rotor quality. [1] There are two phases in a manufacturing process. In the first phase, we do modelling and simulation. All the work in the first phase we can make ourselves. In the second phase, we do assembly of the measuring device including rack, probe and sensors. In this phase, we cannot do all tasks by ourselves. The first phase starts by making a model of the rotor, before that we make rotor model specific probe. Probe dimensions and shape depends on the rotor. When the probe dimensions are ready we start simulation phase. With simulation, we find parameters for voltage and current. Usually, current and frequency are changed according to the simulations. Resolution of the probe is the highest with tuned parameters. In the second phase, we order steel sheets for the probe from a subcontractor. They cut sheets for us according to our CAD model of the probe. Then we order needed measurement devices and materials for rack from subcontractors. Then we assemble whole measurement device and verify, that our simulation results are correct. In this phase, we need rotor from the supplier. After device is assembled and tested, the customer has possibility to buy a training course. At training course, the customer can learn how to use the device, computer software and how to read measurements.

6) Conformance There are two EU directives that all electric devices must meet. These directives are 2013/35/EU and 2014/30/EU. When electric device meets these directives, it can get CE-marking and then this device can be freely sold everywhere in Europe. The purpose of the directive 2013/35/EU is to ensure safe using of electric devices which are installed in the correct way. In the design of our product, we must check that our product meets these requirements. The purpose of the second directive, 2014/30/EU, is to ensure electromagnetic compatibility of an electronic device. The electromagnetic compatibility means that the electronic device must tolerate electromagnetic disturbance and it can’t cause a too much electromagnetic disturbance. That our product meets these requirements we need to design casing that insulates our device from the disturbance and then it can’t cause disturbance to outside to another device.

7) SWOT-analysis Table 1: SWOT-analysis


Critical success factors: • The product has to detect the faults in the rotor even if the rotor differs in size or severity of

porosity from the base project rotor • Finding and seizing the first customers and from that build up the client base • The product has to be customizable with different rotor sizes • We have to offer continuous support to the customers • The usage has to be as simple as possible, preferably “plug and play”

Table 2: Risks along with severity, likelihood with reaction and effect. Scale: 1-5.

Risk Severity Likelihood Reaction or effect

Budget exceeds 4 1

Project plan has to be changed, funding need increases or the end product is going to be more expensive.

Design errors, product does not work as intended

5 2 Product has to be planned, tested and tweaked again.


Underestimating workload and time management

3 1 Need to put down more hours.

Microcontroller and measurement devices do not work as intended

3 2 Other microcontroller or measuring devices has to be order and then tested and tweaked.

Lack of communication or unavailability of group workers 4 1

Project workload has been divided equally. If a group member(s) is unavailable for a longer time his workload will be divided among rest of project group and the workload plan will suffer changes.

Product does not attract any customers

5 2

The product price might be too high or more hours and money has to be spent on marketing the product. We have to listen to the customers need when creating the product.


Supplement: Distribution of work and learning outcomes We divided tasks among group members. Everyone got two tasks and started to work on it. When everyone had done something, we discussed topics and helped each other to complete everyone's topics. Jouni: I learned to search information about markets. This exercise also showed how complicated it is to find out is there space for such a product in the market. To survive in the markets, a company need competitive advantages such as quality, low price or some special knowledge. Competitive advantages you can achieve example by new technology, motivated workers and innovativeness. Also, a product has to launch at the right time. Now it is right time to launch quality products, which helps manufacturers to produce more efficient motors. Ten years ago, there was no such an interest in energy efficient and high-quality motors because there was no pressure to reduce energy consumption at that time. Mark: As an engineering student, this was the first business-related task that I have had to do since I have not taken any Industrial Engineering and Management courses. I have learned to look at a technical project from a business aspect view. This project has helped me understand that a good technical product is not that easy to sell even if it is remarkably good. When I wrote the SWOT-analysis it was interesting to grasp how much could actually go wrong in our project. I learned that if we would have to make this project to an actual startup with investments and real-life customers, we would probably achieve more in the end game if we would hire a professional tradesman. Jani: My contribution to this document was to explore how we can protect the intellectual property of our project, and what requirements it must meet in order it can be sold to customers. Protection of intellectual property was interesting to explore because sometimes I’ve been thinking how these patent and copyright things work. Now I learned what things can protect with patent, utility model, trademark and copyright. I also realized how correlation works between EU directives and standards. And I also learned what directives electrical product must meet when you want to sell it. I think this kind of knowledge will be useful for me in future. İsmet: I have focused on the product/service and market side of this document. It is one of the few times that I am working on a report from business aspects point of view. Although I haven’t taken courses related to Business or Management side, the preparation and research on this report have contributed to me a lot. I think I have learned how to introduce and explain the technical concepts from business aspect view. Also, I have learnt which factors I should take into account while making the market and competitors analysis. I am totally sure that, this experience will help me in my professional life.


References: [1] Myung Jeong, Jangho Yun, Yonghyun Park, Sang Bin Lee, ”Quality Assurance Testing for Screening Defective Aluminum Die-cast Rotors of Squirrel Cage Induction Machines,” IEEE, 2017. [2] Almeida A., Falkner H., Fong J., Jugdoyal K., “EuP Lot 30: Electric Motors and Drives”, 2014 Available: http://www.eup-network.de/fileadmin/user_upload/EuP-LOT-30-Task-2-April-2014.pdf

Final Report Project #28 Diagnosis tool for cage induction ...

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