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Concept Kit
3-Phase AC Motor
Drive Simulation
For Electric Drive Systems
[LTspice Version]


         All Rights Reserved Copyright (C) Bee Technologies Inc. 2012   1
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
              Appendix A: Measured Point of Simulation Circuit (1/2)...........................................................                        12
              Appendix A: Measured Point of Simulation Circuit (2/2)...........................................................                        13
              Appendix B: Evaluation Text......................................................................................................        14
              Appendix C: Gate Signal for Six-Step Control...........................................................................                  15
              Appendix D: 3-Phase AC Motor Model Text (1/2).....................................................................                       16
              Appendix D: 3-Phase AC Motor Model Text (2/2).....................................................................                       17
              Appendix E: Simulation Settings................................................................................................          18




                                              All Rights Reserved Copyright (C) Bee Technologies Inc. 2012                                                       2
1.1) Manufacturer Specification


     Motenergy, Inc (ME0913)
       Motor Electrical Parameters
         •   Operating Voltage Range..........................0 – 72 V MAX
         •   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 102V DC 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

                               All Rights Reserved Copyright (C) Bee Technologies Inc. 2012           3
1.2) Torque and Back-EMF
•    The Torque are defined by :
                                                                               phe : u, v, w
                          Tu = KT ⋅ Iu
                                                                              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
•    The Back-EMF are defined by :                                            ωm : Angular speed of rotor
                          Eu = KE ⋅ ω m
                                                                                                      1 Pound Inch equals 0.11 Nm
                          Ev = K E ⋅ ω m                   (3)
                          Ew = K E ⋅ ω 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
                                    All Rights Reserved Copyright (C) Bee Technologies Inc. 2012                                 4
1.3) Simplified 3-Phase AC Motor Model


                                                       Frequency Response




                                                                                        110uH




                                                                                    105uH




                                                               Phase Resistance (L-L)       : 0.0125Ω
                                                               Phase Inductance             : 105uH
                                                                                             : 110uH




  Fig. 1 Scheme of the 3-Phase Model                                            Fig.2 Phase-to-Ground

                         All Rights Reserved Copyright (C) Bee Technologies Inc. 2012                   5
1.4) The 3-Phase AC Motor Equivalent Circuit
                                              Back-EMF Voltage
                      |Z| - Frequency




                                                                                        Mechanical part




                      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.
                         All Rights Reserved Copyright (C) Bee Technologies Inc. 2012                     6
1.5) Parameters Settings

                                                       Model Parameters:
                                                           LOAD : Load current each phase of motor [Arms]
                                                           – e.g. LL = 125Arms, 140Arms, or 400Arms

                                                           LL : Phase inductance [H]
                                                           – e.g. LL = 10mH, 100mH, or 1H

                                                           RLL : Phase resistance (Phase-to-phase) [Ω]
                                                           – 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.

                            All Rights Reserved Copyright (C) Bee Technologies Inc. 2012                            7
2) Simulation Circuit of 3-Phase AC Motor Model




                              •     Fig.5 Analysis of motor operation powered by
                                    alternating voltage variation involves using the
                                    model of three-phase induction motor.


                   All Rights Reserved Copyright (C) Bee Technologies Inc. 2012        8
2.1) Phase Current Characteristics Under Load Variation
- Simulation Results


                                                                                   Load 50Arms




                                                                                   Load 140Arms




                                                                                   Load 200Arms




                                                                                   Reference of Phase U

                  Fig. 6 Current Characteristics under load Condition
                   All Rights Reserved Copyright (C) Bee Technologies Inc. 2012                     9
2.2) Back-EMF Characteristics Under Load Condition
- Simulation Results

                                                                                   Load 50Arms




                                                                                   Load 140Arms




                                                                                   Load 200Arms




                                                                                   Reference of Phase U

                 Fig. 7 Back-EMF Characteristics under load Condition
                   All Rights Reserved Copyright (C) Bee Technologies Inc. 2012                    10
2.3) Speed and Torque Characteristics At 140Arms
   - Simulation Results


         The Load 140(Arms) is Rated Continuous Current



RPM




                                                                          Tphe: Electric torque produced by each phase



Lb-in
                                                                                                  Tphe ≈ 244Lb-in




                                                                                                    Reference of Phase U


                    Fig. 8 Speed and Torque Characteristics at Load=140Arms

                             All Rights Reserved Copyright (C) Bee Technologies Inc. 2012                            11

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Concept Kit 3-Phase AC Motor Drive Circuit Simulation (LTspice Version)

  • 1. Concept Kit 3-Phase AC Motor Drive Simulation For Electric Drive Systems [LTspice 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 Appendix A: Measured Point of Simulation Circuit (1/2)........................................................... 12 Appendix A: Measured Point of Simulation Circuit (2/2)........................................................... 13 Appendix B: Evaluation Text...................................................................................................... 14 Appendix C: Gate Signal for Six-Step Control........................................................................... 15 Appendix D: 3-Phase AC Motor Model Text (1/2)..................................................................... 16 Appendix D: 3-Phase AC Motor Model Text (2/2)..................................................................... 17 Appendix E: Simulation Settings................................................................................................ 18 All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 2
  • 3. 1.1) Manufacturer Specification Motenergy, Inc (ME0913) Motor Electrical Parameters • Operating Voltage Range..........................0 – 72 V MAX • 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 102V DC 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 All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 3
  • 4. 1.2) Torque and Back-EMF • The Torque are defined by :  phe : u, v, w Tu = KT ⋅ Iu 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 • The Back-EMF are defined by : ωm : Angular speed of rotor Eu = KE ⋅ ω m  1 Pound Inch equals 0.11 Nm Ev = K E ⋅ ω m (3) Ew = K E ⋅ ω 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 All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 4
  • 5. 1.3) Simplified 3-Phase AC Motor Model Frequency Response 110uH 105uH Phase Resistance (L-L) : 0.0125Ω Phase Inductance : 105uH : 110uH Fig. 1 Scheme of the 3-Phase Model Fig.2 Phase-to-Ground All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 5
  • 6. 1.4) The 3-Phase AC Motor Equivalent Circuit Back-EMF Voltage |Z| - Frequency Mechanical part 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. All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 6
  • 7. 1.5) Parameters Settings Model Parameters: LOAD : Load current each phase of motor [Arms] – e.g. LL = 125Arms, 140Arms, or 400Arms LL : Phase inductance [H] – e.g. LL = 10mH, 100mH, or 1H RLL : Phase resistance (Phase-to-phase) [Ω] – 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. All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 7
  • 8. 2) Simulation Circuit of 3-Phase AC Motor Model • Fig.5 Analysis of motor operation powered by alternating voltage variation involves using the model of three-phase induction motor. All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 8
  • 9. 2.1) Phase Current Characteristics Under Load Variation - Simulation Results Load 50Arms Load 140Arms Load 200Arms  Reference of Phase U Fig. 6 Current Characteristics under load Condition All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 9
  • 10. 2.2) Back-EMF Characteristics Under Load Condition - Simulation Results Load 50Arms Load 140Arms Load 200Arms  Reference of Phase U Fig. 7 Back-EMF Characteristics under load Condition All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 10
  • 11. 2.3) Speed and Torque Characteristics At 140Arms - Simulation Results The Load 140(Arms) is Rated Continuous Current RPM Tphe: Electric torque produced by each phase Lb-in Tphe ≈ 244Lb-in  Reference of Phase U Fig. 8 Speed and Torque Characteristics at Load=140Arms All Rights Reserved Copyright (C) Bee Technologies Inc. 2012 11