International Journal of Electrical, Electronics ISSN No. (Online): 2277-2626and Computer Engineering 4(1): 114-119(2015)

Selection & Design of BLDC Motor for Different ApplicationsPriti S. Manware*, Md. Bashir Sheikh** and M.R. Shelke*

*Assistant Professor, Department of Electrical Engineering, PIGCOE, Nagpur, (MS), India,**Assistant Professor, Department of Electrical Engineering, PIET, Nagpur, (MS), India,

(Corresponding author: M.R. Shelke)(Received 04 February, 2015 Accepted 24 March, 2015)

(Published by Research Trend, Website: www.researchtrend.net)

ABSTRACT: BLDC motor is the permanent magnet synchronous motor designed to have a trapezoidal backemf. Due to rugged construction, less control complexity, higher power density, variable speed over a widerange and flexibility to select the rotor construction suitable for particular application, it is being viewed asan alternative for conventional a.c. motors right from residential to commercial & aerospace systems.Rotation of BLDC motor is achieved by energizing the stator phases in a sequence, which depends on therotor position. Hall sensors are used to detect the exact position of the rotor. This paper presents the review,modeling, design & simulation of BLDC motor drive. For the purpose of demonstration, the popularly usedloads are considered. Residential application is studied with fan type load whereas for industrial application,electric vehicle is considered. The simulation is carried out in MATLAB/ Simulink environment.

Keywords: Brushless DC (BLDC) motor, Hall effect sensor, electric vehicle, fan.

I. INTRODUCTION

LDC motor is simple and rugged when compared withd.c. and induction machine. It is same as that of 3 phasea.c. machine but only two phases are excited at a time.Now a days BLDC motor is preferred as compared tobrushed DC motor due to higher reliability, efficiencyand lower noise. This is observed in every field such asin residential, industrial, automotive and householdapplications, because of high torque, lower maintenanceand variable speed control [1-3]. The advantages ofBLDC motor over brushed DC motor are presentedbelow.(i) Armature winding on the stator makes it easy toconduct heat away from the winding.(ii) High speed, high power to size ratio, and no arcingon commutation.(iii) Low inertia and higher acceleration.BLDC motor is more efficient than brushed d.c. motorbecause of the absence of friction due to brushes. Itconsists of 3 phase stator winding, permanent magnetrotor and an electronic controller having inverter andconverter. Input a.c. power is fed to the stator windingthrough the inverter switches as per desired phasesequence. Rotor rotates in the direction based onswitching sequence of the inverter [4], [5]. Position ofthe rotor is sensed by Hall effect sensor. Three sensorsare displaced from each other by 1200 electrical and aremounted on the shaft of the rotor. When the rotormagnetic poles pass near the hall sensors, they supply ahigh or low signal that indicates north or south poles.Based on combination of theseThree hall sensor signals, the exact sequence ofcommutation can be determined.

II. MODELING OF BLDC MOTOR

To derive the model of BLDC motor, followingassumptions are made [6], [7].(i) Currents in rotor due stator harmonic field areneglected.(ii) Iron and stray losses are neglected and damping isprovided by inverter control.The per phase voltage relation for stator side is:

(1)where, Rs is stator resistance/ phase, and eas, ebs, ecs are

the induced emfs assumed to be trapezoidal. The emfinduced/conductor is given as,

e = (Blv) N (2)e = N (B l r ωm) (3)e = N ф ωm

e = λ p ωm volt (4)

where, N is the number of conductor in series/phase, v isthe velocity in (m/s), l is the length of the conductor in(m), r is the radius of rotor bore in (m), ωm is the angularvelocity in (rad/s), B is flux density of the field in(wb/m2), in which the conductors are placed. Theproduct of (Blr) denoted as ф and λ p is the flux linkagein (V.s). There is no change in the rotor reluctance withangle because of non-salient rotor. Assuming threesymmetric phases, self induced emf in the three phasesare Laa = Lbb= Lcc= L and mutual inductances are Lab =Lba= Lca= Lbc=Lcb=M. Substituting these value ofinductance in (1).

I

J EE

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Manware, Sheikh and Shelke 115

(5)

The electromagnetic torque is, = [ + + ]ω

(N.m) (6)

The instantaneous induced emf can be written ase = f (θ )λ ω (7)Where,= λ [f (θ )i + f (θ )i + f (θ )i ] (N.m) (8)The equation of motion for a simple system with inertia J, friction coefficient B and load torque Tl is,+ = − (9)

The relation between electrical rotor speed and rotor position is= (10)

In (5), substitute = −M, the current equations in state space form are obtained as,= [ − − ] + (11)= [ − − ] + (12)= [ − − ] + (13)

From (8) & (9),+ + = λp[f (θ )i + f (θ )i + f (θ )i ]

ω = (Ө ) λ + (Ө ) λ + (Ө ) λ − ω −= (Ө ) λ + (Ө ) λ + (Ө ) λ − ω − (14)

Expressing the above relations in state space aspx = Ax + Bu (15)

where = [ ] and = [ ]

∴ =− 0 0 − λ ( ) 0

0 − 0 − λ ( ) 00 0 − − λ ( ) 0

λ ( ) λ ( ) λ ( ) − 0

=0 0 00 0 00 0 00 0 00 0 0 0

(16)

Eq. (16) represents the dynamic model of a non-salient rotor type BLDC motor.

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Manware, Sheikh and Shelke 116

III. CRITERION FOR SELECTION OF MOTOR

For selection of reliable and efficient motor it isessential that the conditions of service are known. It isnot sufficient to specify the output power in kW andspeed, but it is also necessary to know the followinginformation.(i) Torque at the shaft during running, starting and atdifferent loads.(ii) Accelerating torque and braking torque.(iii) Switching frequency.(iv) Efficiency of motor at different load.(v) Other working requirements.

In studying the behavior of a motor selected for aparticular driven unit, one of criterion is to determinewhether the speed torque characteristic of motor suitsthe requirement imposed by the speed torquecharacteristic of the driven unit. Drive behavior duringthe transient period of a start up, braking or speedchangeover also depends upon how the speed torquecharacteristics of motor and the driven unit vary withspeed. Therefore it is important to study speed-torquecharacteristic to select correct motor and obtain aneconomical drive.

A. Speed-torque characteristics of the motor-loadmechanismsThe speed torque characteristics of a motor is given bythe relation ω= f(TL). It is defined as relationshipbetween the speed at which it is operated and the loadtorque. Speed torque characteristics of different kinds ofload are divided into the following categories.1. Load with Constant torque at all speeds: This kindof load offers passive torque to the motor which isessentially independent of the speed. Examples of suchload are dry friction, cranes during hoisting, hoistwinches, piston pumps operating against a constantpressure head and conveyors.2. Load with linear- rising characteristics: In thistype of load the load torque TL rises in direct proportionto the speed. Popular example is calendaring machine.3. Load with non- linear rising (Parabola)characteristic: In this type of load, the load torque TL isproportional to the square of the speed. Windage torqueis the dominating component of this load. Differentexamples are Fan, Blowers, Centrifugal pumps,Propellers in ships or aeroplanes, water wheels, etc.4. Load with non- linear falling (Hyperbolic)characteristic: For such type of load, the torque TL isinversely proportional to the speed while powerrequired to drive the given unit remains unchanged.Certain types of lathe, boring machine, milling machineand other kinds of metal cutting machine, steel millcoilers fall under this category of loads.

5. Traction loads: These are the high torque loadswhich may vary continuously depending upon speed,time and the path or position of the vehicle duringmotion. The stiction and windage torques playdominating roles during starting and running conditionsrespectively. The performance during acceleration, free-running, costing and deceleration is of importance inthis type of load (Fig. 1). Popular examples are: railwaytraction, electric vehicle etc.

Fig. 1. Speed–time curve of a typical traction load.

B. Load -torque variation versus time characteristics fordifferent types of loadVariation of load-torque with time is of equal or greaterimportance in selection of motor. This variation incertain applications can be periodic and repetitive. Onecycle of variation is called a duty cycle. Different typesof load having different load characteristics areclassified as follows.1. Continuous constant load: These loads operate for along time under the same condition. Examples are papermaking machine, centrifugal pumps, etc.2. Continuous variable load: Hoisting winches, metal

cutting lathes, conveyors are the examples of continuousvariable type load.3. Pulsating load: Reciprocating pump, textile loomsand all machine having crank shaft come under this typeof load.4. Short- time load: Examples are motor generator setfor charging of batteries, servo motors used in remotecontrol of drilling machine and clamping rods.5. Short-time intermittent load: Crane and hoistingmechanism, excavators, roll train are examples of thistype of load.

IV. DESIGN OF BLDC MOTOR FOR ELECTRICVEHICLE

In electric vehicles, the prediction of vehicle propulsionin accordance with power characteristics and torquerequirements of the vehicle is the key component for thedesign of an appropriate traction motor because thespeed-torque characteristics of the traction motorcompletely determines the vehicle performance [8-11].The parameters of vehicle load used for the design ofBLDC motor are presented in Table 1. [12].

Manware, Sheikh and Shelke 116

III. CRITERION FOR SELECTION OF MOTOR

For selection of reliable and efficient motor it isessential that the conditions of service are known. It isnot sufficient to specify the output power in kW andspeed, but it is also necessary to know the followinginformation.(i) Torque at the shaft during running, starting and atdifferent loads.(ii) Accelerating torque and braking torque.(iii) Switching frequency.(iv) Efficiency of motor at different load.(v) Other working requirements.

In studying the behavior of a motor selected for aparticular driven unit, one of criterion is to determinewhether the speed torque characteristic of motor suitsthe requirement imposed by the speed torquecharacteristic of the driven unit. Drive behavior duringthe transient period of a start up, braking or speedchangeover also depends upon how the speed torquecharacteristics of motor and the driven unit vary withspeed. Therefore it is important to study speed-torquecharacteristic to select correct motor and obtain aneconomical drive.

A. Speed-torque characteristics of the motor-loadmechanismsThe speed torque characteristics of a motor is given bythe relation ω= f(TL). It is defined as relationshipbetween the speed at which it is operated and the loadtorque. Speed torque characteristics of different kinds ofload are divided into the following categories.1. Load with Constant torque at all speeds: This kindof load offers passive torque to the motor which isessentially independent of the speed. Examples of suchload are dry friction, cranes during hoisting, hoistwinches, piston pumps operating against a constantpressure head and conveyors.2. Load with linear- rising characteristics: In thistype of load the load torque TL rises in direct proportionto the speed. Popular example is calendaring machine.3. Load with non- linear rising (Parabola)characteristic: In this type of load, the load torque TL isproportional to the square of the speed. Windage torqueis the dominating component of this load. Differentexamples are Fan, Blowers, Centrifugal pumps,Propellers in ships or aeroplanes, water wheels, etc.4. Load with non- linear falling (Hyperbolic)characteristic: For such type of load, the torque TL isinversely proportional to the speed while powerrequired to drive the given unit remains unchanged.Certain types of lathe, boring machine, milling machineand other kinds of metal cutting machine, steel millcoilers fall under this category of loads.

5. Traction loads: These are the high torque loadswhich may vary continuously depending upon speed,time and the path or position of the vehicle duringmotion. The stiction and windage torques playdominating roles during starting and running conditionsrespectively. The performance during acceleration, free-running, costing and deceleration is of importance inthis type of load (Fig. 1). Popular examples are: railwaytraction, electric vehicle etc.

Fig. 1. Speed–time curve of a typical traction load.

B. Load -torque variation versus time characteristics fordifferent types of loadVariation of load-torque with time is of equal or greaterimportance in selection of motor. This variation incertain applications can be periodic and repetitive. Onecycle of variation is called a duty cycle. Different typesof load having different load characteristics areclassified as follows.1. Continuous constant load: These loads operate for along time under the same condition. Examples are papermaking machine, centrifugal pumps, etc.2. Continuous variable load: Hoisting winches, metal

cutting lathes, conveyors are the examples of continuousvariable type load.3. Pulsating load: Reciprocating pump, textile loomsand all machine having crank shaft come under this typeof load.4. Short- time load: Examples are motor generator setfor charging of batteries, servo motors used in remotecontrol of drilling machine and clamping rods.5. Short-time intermittent load: Crane and hoistingmechanism, excavators, roll train are examples of thistype of load.

IV. DESIGN OF BLDC MOTOR FOR ELECTRICVEHICLE

In electric vehicles, the prediction of vehicle propulsionin accordance with power characteristics and torquerequirements of the vehicle is the key component for thedesign of an appropriate traction motor because thespeed-torque characteristics of the traction motorcompletely determines the vehicle performance [8-11].The parameters of vehicle load used for the design ofBLDC motor are presented in Table 1. [12].

Manware, Sheikh and Shelke 116

III. CRITERION FOR SELECTION OF MOTOR

For selection of reliable and efficient motor it isessential that the conditions of service are known. It isnot sufficient to specify the output power in kW andspeed, but it is also necessary to know the followinginformation.(i) Torque at the shaft during running, starting and atdifferent loads.(ii) Accelerating torque and braking torque.(iii) Switching frequency.(iv) Efficiency of motor at different load.(v) Other working requirements.

In studying the behavior of a motor selected for aparticular driven unit, one of criterion is to determinewhether the speed torque characteristic of motor suitsthe requirement imposed by the speed torquecharacteristic of the driven unit. Drive behavior duringthe transient period of a start up, braking or speedchangeover also depends upon how the speed torquecharacteristics of motor and the driven unit vary withspeed. Therefore it is important to study speed-torquecharacteristic to select correct motor and obtain aneconomical drive.

A. Speed-torque characteristics of the motor-loadmechanismsThe speed torque characteristics of a motor is given bythe relation ω= f(TL). It is defined as relationshipbetween the speed at which it is operated and the loadtorque. Speed torque characteristics of different kinds ofload are divided into the following categories.1. Load with Constant torque at all speeds: This kindof load offers passive torque to the motor which isessentially independent of the speed. Examples of suchload are dry friction, cranes during hoisting, hoistwinches, piston pumps operating against a constantpressure head and conveyors.2. Load with linear- rising characteristics: In thistype of load the load torque TL rises in direct proportionto the speed. Popular example is calendaring machine.3. Load with non- linear rising (Parabola)characteristic: In this type of load, the load torque TL isproportional to the square of the speed. Windage torqueis the dominating component of this load. Differentexamples are Fan, Blowers, Centrifugal pumps,Propellers in ships or aeroplanes, water wheels, etc.4. Load with non- linear falling (Hyperbolic)characteristic: For such type of load, the torque TL isinversely proportional to the speed while powerrequired to drive the given unit remains unchanged.Certain types of lathe, boring machine, milling machineand other kinds of metal cutting machine, steel millcoilers fall under this category of loads.

5. Traction loads: These are the high torque loadswhich may vary continuously depending upon speed,time and the path or position of the vehicle duringmotion. The stiction and windage torques playdominating roles during starting and running conditionsrespectively. The performance during acceleration, free-running, costing and deceleration is of importance inthis type of load (Fig. 1). Popular examples are: railwaytraction, electric vehicle etc.

Fig. 1. Speed–time curve of a typical traction load.

B. Load -torque variation versus time characteristics fordifferent types of loadVariation of load-torque with time is of equal or greaterimportance in selection of motor. This variation incertain applications can be periodic and repetitive. Onecycle of variation is called a duty cycle. Different typesof load having different load characteristics areclassified as follows.1. Continuous constant load: These loads operate for along time under the same condition. Examples are papermaking machine, centrifugal pumps, etc.2. Continuous variable load: Hoisting winches, metal

cutting lathes, conveyors are the examples of continuousvariable type load.3. Pulsating load: Reciprocating pump, textile loomsand all machine having crank shaft come under this typeof load.4. Short- time load: Examples are motor generator setfor charging of batteries, servo motors used in remotecontrol of drilling machine and clamping rods.5. Short-time intermittent load: Crane and hoistingmechanism, excavators, roll train are examples of thistype of load.

IV. DESIGN OF BLDC MOTOR FOR ELECTRICVEHICLE

In electric vehicles, the prediction of vehicle propulsionin accordance with power characteristics and torquerequirements of the vehicle is the key component for thedesign of an appropriate traction motor because thespeed-torque characteristics of the traction motorcompletely determines the vehicle performance [8-11].The parameters of vehicle load used for the design ofBLDC motor are presented in Table 1. [12].

Manware, Sheikh and Shelke 117

Table 1: Parameters of Vehicle Load.Symbol

QuantityDescription

M 200 tonne Weight of vehicleD 0.9 m Diameter of driving

wheelG 3% Percentage-gradientR 50 N/tonne Tractive resistance

Γ 4 Gear ratioΗ 90% Gear transmission

efficiencyΑ 2.015 Acceleration

m= meter, N = Newton, %= percentage

A. Torque required to propel the vehicleThe tractive force necessary to propel the vehicle at thewheels is given byFt = Fa + Fg + Fr (N) (17)Where, the force required for giving linear accelerationis,Fa = 277.8 α Me (N) (18)The force required to overcome the gravitational effectis,Fg = 98MG (N) (19)and the force required to overcome resistance to themotion is,Fr = M r (N) (20)The torque required to propel the vehicle is given by,T = Ft D /η 2γ (Nm) (21)where D is diameter of the wheel, η is gear efficiencyand γ is the gear ratio.Substitution of parameter values in (17)-(21) gives,Ft = 192000 NT = 24000 NmAssuming four number of motors, therefore torque

required to be developed by each motor will beT = 6000 Nm

B. Selection of the type of BLDC motor for vehicle loadThe construction of BLDC motor is broadly classifiedinto two topologies i.e. radial flux type and axial fluxtype. The radial flux BLDC motor also called ascylindrical type motor is further classified into outerstator type and outer rotor type. This motor is furthercategorized as surface mounted type and interiorpermanent magnet type [13]. The axial flux BLDCmotor also called as pancake type motor is classified assingle air-gap type and dual air-gap type.The radial flux construction is suitable for low powerdensity applications. It is known that force generated ina motor is a function of the product of flux density inthe core and the slot current. In a radial fluxconstruction, if the current is to be increased, more slotarea is required to maintain constant resistive loss andthe maximum air-gap flux density decreases and vice-

versa. Thus if electric loading gets too high, themagnetic loading must decrease.The electric vehicle application requires high powerdensity of the motor which is possible with dual air-gaptype axial-flux construction [2], [14]. The schematicdiagrams of single air-gap and dual air-gap typepancake motors are shown in Fig. 2 (a) & (b). The detaildesign of a dual air-gap type BLDC motor for vehicleload having parameters given in Table.1 is presented inthis paper. Some authors in the literature have suugestedthe use Spoke type BLDC motor for tractionapplications [15].

Fig. 2. Axial Flux BLDC Motor (a) single air-gap type,(b) dual air-gap type.

C. Design of dual air-gap type BLDC motorThe fixed parameters for the motor are calculated fromthe vehicle parameters (given above). They arepresented in Table 2.

Table 2: Fixed parameter for motor design.

M = meter, rpm = revolution per minute; N-m =Newton meter

Fig. 3. Geometry of motor radius.

Symbol Quantity Description

Sr 1179 rpm Motor SpeedT 6000Nm Required torqueRi 0.15m Inside radiusRo 0.45m Outside radiusNS 24 No. of SlotNph 3 No of phasesNm 4 No. of Magnet

pole

Manware, Sheikh and Shelke 117

Table 1: Parameters of Vehicle Load.Symbol

QuantityDescription

M 200 tonne Weight of vehicleD 0.9 m Diameter of driving

wheelG 3% Percentage-gradientR 50 N/tonne Tractive resistance

Γ 4 Gear ratioΗ 90% Gear transmission

efficiencyΑ 2.015 Acceleration

m= meter, N = Newton, %= percentage

A. Torque required to propel the vehicleThe tractive force necessary to propel the vehicle at thewheels is given byFt = Fa + Fg + Fr (N) (17)Where, the force required for giving linear accelerationis,Fa = 277.8 α Me (N) (18)The force required to overcome the gravitational effectis,Fg = 98MG (N) (19)and the force required to overcome resistance to themotion is,Fr = M r (N) (20)The torque required to propel the vehicle is given by,T = Ft D /η 2γ (Nm) (21)where D is diameter of the wheel, η is gear efficiencyand γ is the gear ratio.Substitution of parameter values in (17)-(21) gives,Ft = 192000 NT = 24000 NmAssuming four number of motors, therefore torque

required to be developed by each motor will beT = 6000 Nm

B. Selection of the type of BLDC motor for vehicle loadThe construction of BLDC motor is broadly classifiedinto two topologies i.e. radial flux type and axial fluxtype. The radial flux BLDC motor also called ascylindrical type motor is further classified into outerstator type and outer rotor type. This motor is furthercategorized as surface mounted type and interiorpermanent magnet type [13]. The axial flux BLDCmotor also called as pancake type motor is classified assingle air-gap type and dual air-gap type.The radial flux construction is suitable for low powerdensity applications. It is known that force generated ina motor is a function of the product of flux density inthe core and the slot current. In a radial fluxconstruction, if the current is to be increased, more slotarea is required to maintain constant resistive loss andthe maximum air-gap flux density decreases and vice-

versa. Thus if electric loading gets too high, themagnetic loading must decrease.The electric vehicle application requires high powerdensity of the motor which is possible with dual air-gaptype axial-flux construction [2], [14]. The schematicdiagrams of single air-gap and dual air-gap typepancake motors are shown in Fig. 2 (a) & (b). The detaildesign of a dual air-gap type BLDC motor for vehicleload having parameters given in Table.1 is presented inthis paper. Some authors in the literature have suugestedthe use Spoke type BLDC motor for tractionapplications [15].

Fig. 2. Axial Flux BLDC Motor (a) single air-gap type,(b) dual air-gap type.

C. Design of dual air-gap type BLDC motorThe fixed parameters for the motor are calculated fromthe vehicle parameters (given above). They arepresented in Table 2.

Table 2: Fixed parameter for motor design.

M = meter, rpm = revolution per minute; N-m =Newton meter

Fig. 3. Geometry of motor radius.

Symbol Quantity Description

Sr 1179 rpm Motor SpeedT 6000Nm Required torqueRi 0.15m Inside radiusRo 0.45m Outside radiusNS 24 No. of SlotNph 3 No of phasesNm 4 No. of Magnet

pole

Manware, Sheikh and Shelke 117

Table 1: Parameters of Vehicle Load.Symbol

QuantityDescription

M 200 tonne Weight of vehicleD 0.9 m Diameter of driving

wheelG 3% Percentage-gradientR 50 N/tonne Tractive resistance

Γ 4 Gear ratioΗ 90% Gear transmission

efficiencyΑ 2.015 Acceleration

m= meter, N = Newton, %= percentage

A. Torque required to propel the vehicleThe tractive force necessary to propel the vehicle at thewheels is given byFt = Fa + Fg + Fr (N) (17)Where, the force required for giving linear accelerationis,Fa = 277.8 α Me (N) (18)The force required to overcome the gravitational effectis,Fg = 98MG (N) (19)and the force required to overcome resistance to themotion is,Fr = M r (N) (20)The torque required to propel the vehicle is given by,T = Ft D /η 2γ (Nm) (21)where D is diameter of the wheel, η is gear efficiencyand γ is the gear ratio.Substitution of parameter values in (17)-(21) gives,Ft = 192000 NT = 24000 NmAssuming four number of motors, therefore torque

required to be developed by each motor will beT = 6000 Nm

B. Selection of the type of BLDC motor for vehicle loadThe construction of BLDC motor is broadly classifiedinto two topologies i.e. radial flux type and axial fluxtype. The radial flux BLDC motor also called ascylindrical type motor is further classified into outerstator type and outer rotor type. This motor is furthercategorized as surface mounted type and interiorpermanent magnet type [13]. The axial flux BLDCmotor also called as pancake type motor is classified assingle air-gap type and dual air-gap type.The radial flux construction is suitable for low powerdensity applications. It is known that force generated ina motor is a function of the product of flux density inthe core and the slot current. In a radial fluxconstruction, if the current is to be increased, more slotarea is required to maintain constant resistive loss andthe maximum air-gap flux density decreases and vice-

versa. Thus if electric loading gets too high, themagnetic loading must decrease.The electric vehicle application requires high powerdensity of the motor which is possible with dual air-gaptype axial-flux construction [2], [14]. The schematicdiagrams of single air-gap and dual air-gap typepancake motors are shown in Fig. 2 (a) & (b). The detaildesign of a dual air-gap type BLDC motor for vehicleload having parameters given in Table.1 is presented inthis paper. Some authors in the literature have suugestedthe use Spoke type BLDC motor for tractionapplications [15].

Fig. 2. Axial Flux BLDC Motor (a) single air-gap type,(b) dual air-gap type.

C. Design of dual air-gap type BLDC motorThe fixed parameters for the motor are calculated fromthe vehicle parameters (given above). They arepresented in Table 2.

Table 2: Fixed parameter for motor design.

M = meter, rpm = revolution per minute; N-m =Newton meter

Fig. 3. Geometry of motor radius.

Symbol Quantity Description

Sr 1179 rpm Motor SpeedT 6000Nm Required torqueRi 0.15m Inside radiusRo 0.45m Outside radiusNS 24 No. of SlotNph 3 No of phasesNm 4 No. of Magnet

pole

Manware, Sheikh and Shelke 118

Fig. 4. Geometry Slot for dual axial flux motor.

When a slotted stator design is chosen there are manycombinations of slots, poles, windings, and phases allowto acceptable motor design. For stator design there is noof stator slot Ns [2].= = 8 ∗ 3 = 24(24)where, number of slots per phase Nsp is 8 and isnumber of phases Nph is 3.

Number of slot per pole per phase Nspp is,= = 2 (25)

Nm is number of magnet poles on the rotor.

Ag is the air gap cross- sectional area given by,= ( ) ( − ) = 0.217 (26)

Where the magnet fraction = 0.86The air gap flux Фg is,∅ = = 0.9 ∗ 0.217 = 0.117 (27)Where, Bg is the air gap flux density.

Back iron width Wbi is given by,= = 0.323 (28)

Where Bmax is the maximum allowable flux density inthe back iron and Bg. is the air gap flux density .Theoutside pole pitch = 0.706m and stacking factor= 0.9.The inner radius Wtbi is= = 0.036m (29)

Where the inside pole pitch = 0.2355m.

Slot bottom width Wsb is,= − = 0.003 (30)Where, inside slot pitch = 0.0391m.

The number of turns per slot ns is equal to= = 5 / (31)

Where, Kd is distribution factor 0.9.

Peak slot current Is is given by= = 6806.97A (32)

Iph is phase current under the assumption that all phasescontribute equally and simultaneously to the motor. Ifall phases Nph are conducting current simultaneouslyand back emf wave is square wave then phase current is= = 453.79 Amp (33)

V. BLDC MOTOR FOR RESIDENTIALAPPLICATION: FAN TYPE LOAD

The radial flux type BLDC motor is of two types. One isrotor inside stator and another is rotor outside of stator.For fan type application, rotor outside statorconstruction is preferred. Conventional ceiling fan usesinduction motor which comparatively has larger size.Induction motor usually operates at high slip due towhich performance of ceiling fan is poor. BLDC motoris advantageous for fan type application because theenergy consumption of BLDC motor is less ascompared to induction motor. Also, relatively the noiseproduced is less [8]-[11]. In fan, the windage dominatesconsequently, load torque is proportional to speedsquared. The speed torque relation for fan type load is[12],= (34)

The power developed at motor shaft is given by,= (35)

This load is unidirectional. It is required to run atconstant speed for a longer time or at several speedsettings or over range of speed. A general scheme ofBLDC motor drive is shown in Fig 5.The 3-phase AC input is first rectified and thenconverted to variable voltage, variable frequency AC byusing 3-phase inverter. Output of the inverter is fed tothe stator winding. Based upon the rotor positionidentified by Hall Effect sensor, the controller generatesappropriate switching pulses for the inverter so as toequalize the actual speed with reference speed underdifferent operating condition.

Manware, Sheikh and Shelke 118

Fig. 4. Geometry Slot for dual axial flux motor.

When a slotted stator design is chosen there are manycombinations of slots, poles, windings, and phases allowto acceptable motor design. For stator design there is noof stator slot Ns [2].= = 8 ∗ 3 = 24(24)where, number of slots per phase Nsp is 8 and isnumber of phases Nph is 3.

Number of slot per pole per phase Nspp is,= = 2 (25)

Nm is number of magnet poles on the rotor.

Ag is the air gap cross- sectional area given by,= ( ) ( − ) = 0.217 (26)

Where the magnet fraction = 0.86The air gap flux Фg is,∅ = = 0.9 ∗ 0.217 = 0.117 (27)Where, Bg is the air gap flux density.

Back iron width Wbi is given by,= = 0.323 (28)

Where Bmax is the maximum allowable flux density inthe back iron and Bg. is the air gap flux density .Theoutside pole pitch = 0.706m and stacking factor= 0.9.The inner radius Wtbi is= = 0.036m (29)

Where the inside pole pitch = 0.2355m.

Slot bottom width Wsb is,= − = 0.003 (30)Where, inside slot pitch = 0.0391m.

The number of turns per slot ns is equal to= = 5 / (31)

Where, Kd is distribution factor 0.9.

Peak slot current Is is given by= = 6806.97A (32)

Iph is phase current under the assumption that all phasescontribute equally and simultaneously to the motor. Ifall phases Nph are conducting current simultaneouslyand back emf wave is square wave then phase current is= = 453.79 Amp (33)

V. BLDC MOTOR FOR RESIDENTIALAPPLICATION: FAN TYPE LOAD

The radial flux type BLDC motor is of two types. One isrotor inside stator and another is rotor outside of stator.For fan type application, rotor outside statorconstruction is preferred. Conventional ceiling fan usesinduction motor which comparatively has larger size.Induction motor usually operates at high slip due towhich performance of ceiling fan is poor. BLDC motoris advantageous for fan type application because theenergy consumption of BLDC motor is less ascompared to induction motor. Also, relatively the noiseproduced is less [8]-[11]. In fan, the windage dominatesconsequently, load torque is proportional to speedsquared. The speed torque relation for fan type load is[12],= (34)

The power developed at motor shaft is given by,= (35)

This load is unidirectional. It is required to run atconstant speed for a longer time or at several speedsettings or over range of speed. A general scheme ofBLDC motor drive is shown in Fig 5.The 3-phase AC input is first rectified and thenconverted to variable voltage, variable frequency AC byusing 3-phase inverter. Output of the inverter is fed tothe stator winding. Based upon the rotor positionidentified by Hall Effect sensor, the controller generatesappropriate switching pulses for the inverter so as toequalize the actual speed with reference speed underdifferent operating condition.

Manware, Sheikh and Shelke 118

Fig. 4. Geometry Slot for dual axial flux motor.

When a slotted stator design is chosen there are manycombinations of slots, poles, windings, and phases allowto acceptable motor design. For stator design there is noof stator slot Ns [2].= = 8 ∗ 3 = 24(24)where, number of slots per phase Nsp is 8 and isnumber of phases Nph is 3.

Number of slot per pole per phase Nspp is,= = 2 (25)

Nm is number of magnet poles on the rotor.

Ag is the air gap cross- sectional area given by,= ( ) ( − ) = 0.217 (26)

Where the magnet fraction = 0.86The air gap flux Фg is,∅ = = 0.9 ∗ 0.217 = 0.117 (27)Where, Bg is the air gap flux density.

Back iron width Wbi is given by,= = 0.323 (28)

Where Bmax is the maximum allowable flux density inthe back iron and Bg. is the air gap flux density .Theoutside pole pitch = 0.706m and stacking factor= 0.9.The inner radius Wtbi is= = 0.036m (29)

Where the inside pole pitch = 0.2355m.

Slot bottom width Wsb is,= − = 0.003 (30)Where, inside slot pitch = 0.0391m.

The number of turns per slot ns is equal to= = 5 / (31)

Where, Kd is distribution factor 0.9.

Peak slot current Is is given by= = 6806.97A (32)

Iph is phase current under the assumption that all phasescontribute equally and simultaneously to the motor. Ifall phases Nph are conducting current simultaneouslyand back emf wave is square wave then phase current is= = 453.79 Amp (33)

V. BLDC MOTOR FOR RESIDENTIALAPPLICATION: FAN TYPE LOAD

The radial flux type BLDC motor is of two types. One isrotor inside stator and another is rotor outside of stator.For fan type application, rotor outside statorconstruction is preferred. Conventional ceiling fan usesinduction motor which comparatively has larger size.Induction motor usually operates at high slip due towhich performance of ceiling fan is poor. BLDC motoris advantageous for fan type application because theenergy consumption of BLDC motor is less ascompared to induction motor. Also, relatively the noiseproduced is less [8]-[11]. In fan, the windage dominatesconsequently, load torque is proportional to speedsquared. The speed torque relation for fan type load is[12],= (34)

The power developed at motor shaft is given by,= (35)

This load is unidirectional. It is required to run atconstant speed for a longer time or at several speedsettings or over range of speed. A general scheme ofBLDC motor drive is shown in Fig 5.The 3-phase AC input is first rectified and thenconverted to variable voltage, variable frequency AC byusing 3-phase inverter. Output of the inverter is fed tothe stator winding. Based upon the rotor positionidentified by Hall Effect sensor, the controller generatesappropriate switching pulses for the inverter so as toequalize the actual speed with reference speed underdifferent operating condition.

Manware, Sheikh and Shelke 119

Fig. 5. BLDC motor drive.

VI. CONCLUSION

In this paper, a detailed study of BLDC motor designfor Electric vehicle load for industrial application andBLDC motor drive feeding fan type load for residentialapplication is presented. Motor is designed for specialapplication that is electric vehicle also motor dynamicmodel is derived and simulation study is carried out inMATLAB/Simulink environment under four differentoperating conditions. Design and simulation resultproves the feasibility of this motor drive for bothindustrial and residential load. The inherent advantagesof BLDC motor drive related with variable speed, highefficiency, low maintains and high speed range areextended to this load. In future, it is expected thatBLDC motor will replace the conventional inductionmotor in many domestic & industrial applications.

REFERENCES

[1]. R. Krishnan, Electric Motor Drives: Modeling,Analysis and Control, Prentice Hall, 2001.[2]. D. Hanselman, Brushless Permanent Magnet MotorDesign, McGraw-Hill.[3]. P.C. Krause, O. Wasynczuk , Analysis of ElectricMachinery and Drive Systems, Wiley India.[4]. S. Prakashand, R. Dhanasekaramm“ Modelling andsimulation of closed loop controlled buck converterfedpmbldc drive system” Research Journal of AppliedScience, Engineering and Technology 3(4): 284-289,2011.[5]. Vandana Govindan T.K , Anish Gopinath, “DSPbased Speed Control of Permanent Magnet BrushlessDC Motor”, IJCA Special Issue on “ComputationalScience - New Dimensions & Perspectives” NCCSE,2011.[6]. De,S., Rajne, M., Poosapati, S., Patel, C.,Gopakumar, K. “Low inductance axial flux BLDCmotor drive for more electric aircraft” IEEE Aerospaceconference -2011.

[7]. Yong-Han Kim, Bo-Suk Yang , Chang-Joon Kim,“Noise Source Identification of Fan- Small BLDCMotor System for Refrigerators”, International Journalof Rotating Machinery Volume 2006, Article ID 63214,pp 1–7.[8]. J.B. Gupta, Utilization of Electric Power & ElectricTraction, S. K. Kataria & Sons, pp 411- 480.[9]. Jinsong Kang, Guoqing Xu,“ Research on Field-Weakening Based on Reactive Power with BLDCMotor for Electric Vehicle Application” IEEEInternational Conference on Integration TechnologyMarch 20-24, 2007, Shenzhen, China Proceedings2007.[10]. David Dorrell, Mircea Popescu, “Analysis andDesign Techniques Applied to Hybrid Vehicle DriveMachines—Assessment of Alternative IPM andInduction Motor Topologies”. IEEE Trans on Ind.Electronics, Vol 59, No. 10, Oct 2012.[11]. Nam-Hun Kim, Oh Yang, Min-Huei Kim, “BLDCMotor Control Algorithm for Industrial ApplicationsUsing a General Purpose Processor”. Journal of PowerElectronics, Vol. 7, No. 2, April 2007.[12]. Y. Kim, Se. Rhyu, “Parameter determination ofBLDC motor considering the dynamic equation ofVehicle”, XIXI International conference on Electricalmachine, ICEM 2010, Rome.[13]. Gianmario Pellegrino, Paolo Guglielmi, Barbarazzo, “Performance Comparison Between Surface-Mounted and Interior PM Motor Drives for ElectricVehicle Application’’, IEEE Transactions on IndustrialElectronics, vol. 59, no. 2, February 2012.[14]. Su-Beom Park, Ji, Young, “Characteristic analysisof the Axial-Flux Type Brushless DC Motor UsingImage method”, 15th COMPUMAG Conference on thecomputation of Electromagnetic Field, June 2005.[15]. B. Lee, G. Kang, “ Design of spoke type BLDCmotor with high power density for tractionapplication,7803-8486 – 5/4/2004 IEEE.