University of Idaho College of engineering

Electrical and Computer Engineering

Department

ECE 427: Power Electronics

Solid State Diodes Testing & Characterization

Spring 2020

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Objectives:

The objective of this experiment can be listed as follow:

1) Learn how to use LTspiceXVII – a virtual instrument and automated measurement program.

2) To observe the output waveform of half wave rectifier with and without filter.

Part 1 – Tutorial on LTspiceXVII

Installation:

• Most computer in ECE labs are prepared with the standard version of LTspice. • Also you can find a FREE VERSION to download LTspice here OR search for LTspice

| Design Center | Analog Devices , then download. • The installation is easy, just follow the instructions on the screen.

Run LTspice

Prepare a circuit for simulation

LTspice has the following features:

1. New Schematic.

2. Toolbar

3. LTspiceXVII - Keyboard Shortcut a) Click the Tools menu and then click Control Panel. b) Click on the Drafting Options tab and then click the Hot Keys [*] button. c) Click on the tab for the editor/viewer (Schematic, Symbol, Waveform, or Netlist) you

wish to edit/view the keyboard shortcuts for.

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d) Click on any specific command's shortcut and it should turn from grey to black. While it is black, press the keyboard key or key combination you wish to assign to that command, and you should see it change

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Part 2: (A): Half-Wave Rectifier.

Half wave rectifier is the most-commonly-used rectifier configurations. It consists of

one rectifier circuit with a common load. Thus, the output voltage waveform contains

half sinusoids in the two half-cycles of the AC input signal. The output of a rectifier is

a pulsating DC consisting of a DC component and superimposed ripple. A way to

eliminate or reduce the ripple to the required level is to use a filter.

The advantage of HWR is Less complex (requires only one diode and transformer is

not required). On the other hand, the disadvantages are only allowing a half-cycle

through per wave, which leads to power loss. Also, it produces low output voltage, not

purely DC output current, and contains a lot of ripple. Fig. 1. Shows the circuit

diagram of HWR.

In experiment, use your simulation software to construct the circuit in Fig. 1. By

following the steps below.

Fig.1. Half wave rectifier.

1. Select a component (drag and click) or write then click for component. (While placing the

component on the schematic you can also use CTRL+R to rotate it).

2. To set the value of the component (Right click on it and set).

3. Right click on the resistor and set the resistance to 1k.

4. Right click on the diode, click ‘Pick New Diode’ and select the 1N4148. Note various diode

models can be selected. We are choosing a basic silicon diode.

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5. Add a voltage source (sinusoidal input). Click on add component on your toolbar and scroll to

the right and select voltage. If you end up in Diode or other sub-library, just scroll to the left

and on the top, you will see [..] icon. Double click and you will come back to the main library.

Right click on the voltage source and set it to a 1000 Hz sine wave with 5 V amplitude. Make

sure to select SINE function.

6. Connect wires (shortcut F3), and draw the schematic diagram in Fig. 1

7. Add net names: e.g. Vin, Vout. This labels voltage nodes for later reference. Alternatively,

you can right click on a wire and select Label Net. You can also use shortcut F4 (go to Edit-

> to see other shortcuts).

Note, if you have zoomed out or zoomed in, hit Space Bar to redraw it and fit the schematic to the screen. SIMULATION: To simulate the circuit using a transient analysis. 1. Click the simulate button on the toolbar (running person icon) and select the Transient menu.

2. Set the stop time to 0.01s (10 ms), time to start saving data to 0, and max time step to 0.0001s.

Note, if you choose very large time step, you may not have good resolution; if you choose very small-time step, your simulation will take ages to finish. In any case, LTspice will adjust the time step dynamically but it will not exceed the max time step. Normally stop time should be long enough for transient to pass; it will depend on your

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circuit (15 ms is good enough for our example). Your time step should be 1/10th or 1/100th of your stop time. Note that LTspice gives you the second option (time to start saving data) so you can choose to save a few periods towards the end instead of saving the entire dataset.

3. After the simulation completes, you will see waveform window. Click with the voltage probe

on the wires in the schematic where we want to measure the voltage (Vin and Vout) and you should see the following output. Does this look familiar?

Takeaway notes:

1- To save the data go to File->Export. select the signals click OK. the text file will be in the selected directory with the time and other signals. Also, you can use this file in MATLAB or Excel or whatever...

2- Use Marker: left clicking on the waveform label on the top (e.g. I(Iout)) and by moving the cursor around. You can check the x and y values in the little window that pops up. Click on the label of another signal again to bring up a second cursor.

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Lab Exercise: Half-Wave Rectifier with Filter

Adding smoothing capacitor

1. Add a capacitor to the output of the half-wave rectifier as shown in Fig.2.

Fig.2. half wave rectifier with capacitor

2. Can you observe the ripples at the output? How do they change with different capacitance

values?

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Homework:

7. Full-Wave Rectifier Construct the circuit below and fill-up the following questions.

A. Draw the circuit schematic with and without Capacitor.

B. Use your simulation software to simulate the circuit with and without Capacitor.

C. Discuss your results.

8. 3-Phase Half Wave Rectifier.

In the following circuit, select your own values of diodes, resistor and capacitor. A. Draw the circuit schematic diagram for this question.

B. Use your simulation software to simulate the circuit and see the effect of capacitor on the

Vout.

C. Discuss your results.

LTspice Helpful Links: •Download: http://www.linear.com/designtools/software/#LTspice •Getting-Started Tutorial: http://cds.linear.com/docs/en/software-and-imulation/LTspiceGettingStartedGuide.pdf •Simulating -AC Analysis: http://www.linear.com/solutions/4581 •Simulating -DC/Transient Analysis: http://www.seas.upenn.edu/~jan/LTspice/ESE216LTSpiceDC&TransientSimulations.pdf •Simulating -DC Operating Points: http://www.zen22142.zen.co.uk/ltspice/dccircuits.htm •Importing/Exporting PWL (Piecewise Linear) Signals: http://www.linear.com/solutions/1815 •Adding Third-Party Models: http://www.linear.com/solutions/1083 •Importing/Exporting WAVE file (audio signals): http://electrostud.wikia.com/wiki/Using_WAVE_files_as_input/output_in_LTSpice •LTspice for Mac: https://www.youtube.com/watch?v=gdRqZwrrXwU