This document provides an overview of modeling a 3-phase AC motor for electric drive system simulation in PSpice. It includes the motor specifications, modeling of torque and back-EMF, a simplified 3-phase AC motor model, the equivalent circuit model, and appendices describing simulation settings and evaluation. The modeling aims to simulate phase current, back-EMF, speed, torque, power output and efficiency characteristics of the 3-phase AC motor under different load conditions.

1. Concept Kit
Modeling of 3-Phase AC Motor
Drive Simulation
For Electric Drive Systems
[PSpice Version]
All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 1

2. Contents
Slide #
1. Modeling of 3-Phase AC Motor Model
1.1 Manufacturer Specification......................................................................................................... 3
1.2 Torque and Back-EMF............................................................................................................... 4
1.3 Simplified 3-Phase AC Motor Model......................................................................................... 5
1.4 The 3-Phase AC Motor Equivalent Circuit................................................................................. 6
1.5 Parameter Settings..................................................................................................................... 7
2. Simulation Circuit of 3-Phase AC Motor Model................................................................................ 8
2.1 Phase Current Characteristics Under Load Variation................................................................ 9
2.2 Back-EMF Characteristics Under Load Condition..................................................................... 10
2.3 Speed and Torque Characteristics At 140Arms........................................................................ 11
2.4 Power Output and Efficiency Characteristics At 140Arms......................................................... 12
Appendix A: Measured Point of Simulation Circuit (1/2)........................................................... 13
Appendix A: Measured Point of Simulation Circuit (2/2)........................................................... 14
Appendix B: Evaluation Text...................................................................................................... 15
Appendix C: Gate Signal for Six-Step Control........................................................................... 16
Appendix D: 3-Phase AC Motor Model Text (1/2)..................................................................... 17
Appendix D: 3-Phase AC Motor Model Text (2/2)..................................................................... 18
Appendix E: Simulation Settings................................................................................................ 19
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3. 1.1) Manufacturer Specification
Motenergy, Inc (ME0913)
Motor Electrical Parameters
• Operating Voltage Range..........................0 – 72 VMAX
• Rated Continuous Current........................140 Arms
• Peak Stalled Current.................................400 Arms
• Voltage Constant.......................................50 RPM/V
• Phase Resistance (L-L).............................0.0125 Ω
• Phase Inductance......................................105uH at 120Hz, 110uH at 1kHz
• Maximum Continuous Power Rating……..17KW at 102VDC Battery Voltage
14.3KW at 84VDC Battery Voltage
12KW at 72VDC Battery Voltage
Motor Mechanical Parameters
• Rated Speed.............................................3000 RPM
• Maximum Speed.......................................5000 RPM
• Rated Torque............................................288 Lb-in
• Torque Constant.......................................1.6 Lb-in/A
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4. 1.2) Torque and Back-EMF
• The Torque are defined by :
Tu  KT  Iu  phe : u, v, w
Vphe : Phase voltage applied from inverter to motor
Tv  KT  Iv (1)
VAC : Operating voltage range (Maximum voltage)
Tw  KT  Iw
VBAT : DC Voltage applied from battery
Te  Tu  Tv  Tw (2) Iphe : Phase current
At 140Arms (Rated Continuous Current) Tphe : Electric torque produced by u, v, w phase
KT = 1.6 Lb-in/A
Te : Electric torque produced by motor
Ephe : Phase Back-EMF
Tphe = 1.6  140 = 224Lb-in KE : Back-EMF constant
Te = 224*3= 672Lb-in KT : Torque constant
ωm : Angular speed of rotor
• The Back-EMF are defined by :
Eu  KE  m  1 Pound Inch equals 0.11 Nm
Ev  KE  m (3)
Ew  KE  m
At 5000 RPM (Maximum Speed)
Ephe ≈ VBAT (In an ideal motor, R and L are zero)
Ephe = 102V
KE = Ephe /ωm = 102 / 5000
KE ≈ 0.02V/RPM
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5. 1.3) Simplified 3-Phase AC Motor Model
Frequency Response
110uH
105uH
BEMF1
R1 L1
U 1 2
R2 L2
BEMF2 Phase Resistance (L-L) : 0.0125Ω
V 1 2 Phase Inductance : 105uH
N0 : 110uH
BEMF3
R3 L3
W 1 2
Fig. 1 Scheme of the 3-Phase Model Fig.2 Phase-to-Ground
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6. 1.4) The 3-Phase AC Motor Equivalent Circuit
E1
eu + emf_u PARAMETERS: PARAMETERS:
+
|Z| - Frequency -
- Back-EMF Voltage RLL = 0.0125 LOAD = 140
LL = 105U
lim_u KT = 1.6
Vu 0
U1 KE = 0.02
n1 emf_u
U OUT+ IN+ IN+ OUT+
1
TQSP 2
sp_u OUT- IN- IN- OUT-
tu 0 0 lim_v
0
E2 IN+ OUT+
ev + + emf_v IN- OUT-
-
- 0 lim_w
0
Vv 0
U2 IN+ OUT+
n2 emf_v
V OUT+ IN+ IN- OUT-
1
TQSP 2 sp_v OUT- IN- 0 Mechanical part
tv 0 0
torque
E3
ew + + emf_w
-
- IN+ OUT+
IN- OUT-
Vw 0
U3
n3 emf_w 0 0 speed
W OUT+ IN+
TQSP 2
1
sp_w OUT- IN-
tw 0 sp_u
mul
sp_v IN+ OUT+
sp_w IN- OUT-
0 0
N0
Fig. 3 Three-Phase AC Motor Equivalent Circuit
• This figure shows the equivalent circuit of AC motor model that includes the |Z|-
frequency part ,Back-EMF voltage part ,and Mechanical part.
• The Back-EMF voltage is the voltage generated across the motor's terminals as the
windings move through the motor's magnetic field.
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7. 1.5) Parameters Settings
Model Parameters:
LOAD : Load current each phase of motor [Arms]
U1 – e.g. LL = 125Arms, 140Arms, or 400Arms
ME0913
1
LL : Phase inductance [H]
LL = 105U
– e.g. LL = 10mH, 100mH, or 1H
2
3
M 4 RLL = 0.0125
N0 KE = 0.02
KT = 1.6 RLL : Phase resistance (Phase-to-phase) [Ω]
LOAD = 140 – e.g. RLL = 10mΩ, 100mΩ, or 1Ω
KE : Back-EMF constant [V/RPM]
– e.g. KE= 0.01, 0.05, or 0.1
Fig. 4 Symbol of 3-Phase Induction Motor KT : Torque constant [Lb-in/A]
– e.g. KT= 0.1, 0.5, or 1
 1 Pound Inch equals 0.11 Nm
• From the 3-Phase Induction Motor specification, the model is characterized by setting parameters
LL, RLL, KE, KT and LOAD.
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8. 2) Simulation Circuit of 3-Phase AC Motor Model
V1 S1 D1 S3 D3 S5 D5
102V UP + + DMOD_01 VP + + DMOD_01 WP + + DMOD_01
- - - - - -
0 0 0 U1
ME0913
RU U 1
4
N0
RV
RW
V
W
2
3
M N0
N0
RU, RV, RW: 173.75m
V2
102V
LL = 105U
S2 D2 S4 D4 S6 D6 RLL = 0.0125
UD + + DMOD_01 VD + + DMOD_01 WD + + DMOD_01 KE = 0.02
KT = 1.6
- - - - - - LOAD = 140
0 0 0
0
• Fig.5 Analysis of motor operation powered by
UP UD VP VD WP WD
alternating voltage variation involves using the
model of three-phase induction motor.
U2
UP
VP
WP
UD
VD
WD
GDRV
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9. 2.1) Phase Current Characteristics Under Load Variation
- Simulation Results
500A
Load 50Arms
0A
-500A
0s 500ms
500A I(RU)/SQRT(2)
Time
Load 140Arms
0A
-500A
0s 500ms
500A I(RU)/SQRT(2)
Time Load 200Arms
0A
-500A
0s 500ms
I(RU)/SQRT(2)
Time  Reference of Phase U
Fig. 6 Current Characteristics under load Condition
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10. 2.2) Back-EMF Characteristics Under Load Condition
- Simulation Results
200V
Load 50Arms
100V
0V
-100V
-200V
0s 500ms
200V V(X_U1.EU)
Time Load 140Arms
100V
0V
-100V
-200V
0s 500ms
200V V(X_U1.EU)
Time Load 200Arms
100V
0V
-100V
-200V
0s 500ms
V(X_U1.EU)
Time  Reference of Phase U
Fig. 7 Back-EMF Characteristics under load Condition
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11. 2.3) Speed and Torque Characteristics At 140Arms
- Simulation Results
4.0KV
The Load 140(Arms) is Rated Continuous Current
3.0KV
(464.146m,3.2311K)
RPM 2.0KV
1.0KV
SEL>>
0V
V(X_U1.speed)
1.0KV
Tphe: Electric torque produced by each phase
Lb-in
0.5KV
(446.486m,223.728)
0V
0s 500ms
V(X_U1.tu)
Time  Reference of Phase U
Fig. 8 Speed and Torque Characteristics at Load=140Arms
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12. 2.4) Power Output and Efficiency Characteristics At 140Arms
- Simulation Results
20KW
At Load=140Arms, Power Output ≈ 13.7 [KW]
(960.616m,13.662K)
Watt 10KW
SEL>>
0W
RMS(V(RU:1,N0))*RMS(I(RU))
100
At Load=140Arms, Efficiency ≈ 82 [%]
(962.500m,81.941)
[%]
50
0
0.5s 1.0s
100*( (RMS(V(U,N0))*RMS(I(RU))) / (RMS(V(RU:1,N0))*RMS(I(RU))) )
Time  Reference of Phase U
Fig. 9 Power Output and Efficiency Characteristics at Load=140Arms
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