Docstoc

Hybrid Electric Vehicle Active Rectifier Performance Analysis

Document Sample
Hybrid Electric Vehicle Active Rectifier Performance Analysis Powered By Docstoc
					Hybrid Electric Vehicle Active Rectifier
         Performance Analysis




               Ean A. Amon
           Oregon State University
                              Material Covered



   Hybrid Electric Vehicle Design

   Fault Tolerance

   Passive Rectification

   Active Rectification

   Voltage-Controlled Active Rectifier Investigations

   Current-Controlled Active Rectifier Investigations

   Hardware Implementation
                   Hybrid Electric Vehicle Design



   High Efficiency – extended operating range

   Reduced EMI – causes interference in communications and control systems

   Fault Tolerance – limp home capability
Fault Tolerance of Permanent Magnet Machine Systems


   Multi-Phase Designs

   Independent Phase Configurations
      • separate H-bridge rectifiers
      • isolation of both electrical and magnetic circuits
   Intelligent Control
      • isolate damaged windings
      • maintain output in post-fault state
                  Passive Rectifier Investigations


   Baseline Comparison of Active Rectifier Results

   Verification of Equivalent Circuit PM Machine Models


           System Parameters:                - 600V dc bus
                                             - 440kW resistive load
                                             - 2400µF bus capacitance

           Generator Parameters:             - 1.2 kHz electrical frequency
                                             - 98% efficient
                                             - 5% full-load voltage drop

           Generator Configurations:         - 3-phase wye-connected
                                             - 6-phase wye-connected
                                             - 6-phase independent windings
Passive Rectifier with PM Synchronous Machine Model


   PM Synchronous Machine model in Matlab Simulink utilized

     •   3-phase configurable machine

     •   torque driven model, mechanical frequency feedback

     •   no-load peak phase voltage = 368.5V (to achieve 600V dc)

     •   phase resistance = 8.0mΩ (calculated for 98% efficiency)

     •   phase inductance = 2.7µH (calculated for 5% voltage drop under full load)


         Note: Simulations were also carried out using 10% of the calculated
         inductance (0.27µH) due to significant generator voltage distortion at high
         frequency.
Passive Rectifier with PM Synchronous Machine Model
                      (continued)

   3-phase (6-pulse) diode rectifier connected to PMSM model
   2400µF dc bus capacitance
   440kW resistive load (0.818Ω at 600V dc)

Matlab Simulink Schematic:
Passive Rectifier with PM Synchronous Machine Model
                      (continued)


          dc bus voltage with calculated inductance (2.7µH)




                                        approx. 4.4V ripple
Passive Rectifier with PM Synchronous Machine Model
                      (continued)


       dc bus voltage waveforms with reduced inductance (0.27µH)




                                         approx. 16.4V ripple
    Passive Rectifier with PM Synchronous Machine Model
                          (continued)


                             Harmonic Analysis of DC Bus Voltage


  2.2V                                                     8.2V




     calculated inductance (2.7µH)                             reduced inductance (0.27µH)
            (THD = 0.72%)                                            (THD = 1.37%)

Note: Results with full calculated inductance are shown for all further passive rectifier simulations.
Passive Rectifier with Equivalent Circuit Generator Model


    PMSM model removed
    equivalent circuit: 3 ac sources, 120° spacing, peak phase voltage = 368.5V
    phase resistance = 8.0mΩ
    phase inductance = 2.7µH

 Matlab Simulink Schematic:
   Verification of Equivalent Circuit Model




equivalent circuit model         PMSM model
Passive Rectifier with 6-Phase Wye-Connected Generator


   6 ac sources, 60° spacing, peak phase voltage = 350V

   phase resistance and inductance recalculated
     • phase resistance = 12mΩ
     • phase inductance = 4.1µH
Matlab Simulink Schematic:
Passive Rectifier with 6-Phase Wye-Connected Generator
                       (continued)




    dc bus voltage waveforms and FFT

   dc bus ripple = 3.6V

   THD = 0.59%

   voltage ripple and THD slightly
    reduced from 3-phase case
Passive Rectifier with 6-Phase Independent Generator


   6 ac sources, 60° spacing, peak phase voltage = 698.7V

   phase resistance and inductance recalculated
     • phase resistance = 49mΩ
     • phase inductance = 16µH
Matlab Simulink Schematic:
    Passive Rectifier with 6-Phase Independent Generator
                          (continued)




     dc bus voltage waveforms and FFT

    dc ripple = 3.7V

    THD = 0.60%

    dc bus ripple and THD nearly
     unchanged from wye-connected case
     with increased phase voltage and
     phase impedance
    Active Rectifier Investigations with Voltage Control


    active rectifiers simulated in three configurations
      • 3-phase wye, 6-phase wye, and 6-phase independent

    simple voltage control – sinusoidal modulation referencing dc bus voltage error
       • product of per-unit sinusoidal input voltage and calculated modulation index

    “Universal Bridge” block configured as IGBT “boost” rectifier
      • single 3-phase, dual 3-phase, and H-bridge configurations

    RC snubber circuits utilized on all IGBT/diode pairs
      • necessary for simulation convergence
      • resistance = 50Ω, capacitance = 250nF

    switching frequencies of 10 kHz, 15 kHz, and 20 kHz
            with dead times of 2µs and 5µs
    Simple Voltage Control



                             (Mavg)Vdc
  m  G  (Vdc  Vref ) 
                               Vref




(control scheme for 3-phase active rectifier)
           3-Phase Wye-Connected Active Rectifier
                    with Voltage Control


   peak phase voltage lowered to 285.8V (350VLL rms)
   phase resistance and inductance unchanged from 3-phase passive rectifier
     • 8.0mΩ and 2.7µH respectively
Matlab Simulink Schematic:
   3-Phase Wye-Connected Active Rectifier
       with Voltage Control (continued)




     dc ripple = 26V              dc ripple = 30V




fs = 10 kHz, 2µs dead time   fs = 10 kHz, 5µs dead time
   3-Phase Wye-Connected Active Rectifier
       with Voltage Control (continued)




    dc ripple = 10.5V             dc ripple = 10V




fs = 15 kHz, 2µs dead time   fs = 15 kHz, 5µs dead time
   3-Phase Wye-Connected Active Rectifier
       with Voltage Control (continued)




     dc ripple = 10V               dc ripple = 8V




fs = 20 kHz, 2µs dead time   fs = 20 kHz, 5µs dead time
    3-Phase Wye-Connected Active Rectifier
        with Voltage Control (continued)


                             15 kHz, 2µs dead time results:

                                dominant switching harmonic,
                                 approx. 2.6V at sideband of fs
                                THD = 0.44%



fs = 15 kHz, 2µs dead time


                             15 kHz, 5µs dead time results:

                                dominant switching harmonic,
                                 approx. 2.1V at sideband of fs
                                THD = 0.48%



fs = 15 kHz, 5µs dead time
           6-Phase Wye-Connected Active Rectifier
                    with Voltage Control


          Matlab Simulink Schematic:




   peak phase voltage is 285.8V

   utilizes two 3-phase boost
    rectifiers in parallel

   control scheme incorporates
    sine-triangle comparators for
    3 additional phases

   phase resistance and inductance unchanged from 6-phase passive rectifier
     • 12.0mΩ and 4.1µH respectively
      6-Phase Wye-Connected Active Rectifier
          with Voltage Control (continued)




fs = 15 kHz, 5µs dead time

   dc ripple approx. 4.7V
   THD = 0.44%
   dominant switching
    harmonic, approx.
    1.1V at 2fs
              6-Phase Independent Active Rectifier
                      with Voltage Control


            Matlab Simulink Schematic:




   peak phase voltage is 495V
    (350V rms)

   phase resistance and inductance
    unchanged from 6-phase passive
    rectifier model
      • 49.0mΩ and 16.0µH
          respectively

   single H-bridge rectifier for each
    phase
              6-Phase Independent Active Rectifier
                with Voltage Control (continued)


   same control scheme algorithm

   additional sine-triangle
    comparators for offset gating of
    conducting switch pairs

     •   two conducting devices do
         not switch in same instance

     •   reduces switching
         harmonics
         6-Phase Independent Active Rectifier
           with Voltage Control (continued)




fs = 15 kHz, 5µs dead time

   dc ripple approx. 4.4V
   THD = 0.60%
   dominant switching
    harmonic, approx.
    1.7V at 2fs
               Current Control of Active Rectifiers




current control – compares actual input currents with reference currents,
                       forces current to follow a sinusoidal waveform



Operation:

1.   reference currents (Iref) calculated using dc       I ref  Vdc  Vdc ,ref   G  Vs , pu
     bus voltage error


                                                         I mod  I s , pu  I ref 
2.   subtracting reference currents from per unit                                        Vdc
     source currents produces modulation signal
     (Imod)                                                                             Vdc,ref

3.   modulation signal is then used in
     sine-triangle comparison
                Updated Simulation Specifications


       New generator specifications provided by BAE Systems

    •       6 phase windings configured as two synchronized 3-phase sets
    •       neutral access for independent phase capability
    •       back EMF of 380VLL rms (peak phase voltage 310.3V, 219.4V rms)
    •       phase inductace = 60µH
    •       phase resistance = 48mΩ
    •       electrical frequency = 708 Hz (10 pole pairs @ 4250 rpm)

       switching frequency of 15 kHz, dead time of 5µs

       400 kW resistive load, 2400µF dc bus capacitance

       snubber impedance increased
    •       resistance = 100Ω, capacitance = 176.84nF
Current-Controlled 2x3-Phase Wye Configuration


Matlab Simulink Schematic




                               Schematic of IGBT Bridge
Current-Controlled 2x3-Phase Wye Configuration
                  (continued)


Schematic of PWM Generator
  (current-control scheme)




                             current-control waveforms (phase A)




                             modulation & gating signals (phase A)
 Current-Controlled 2x3-Phase Wye Configuration
                   (continued)




device currents (phase A rectifier leg)   source voltage and current waveforms
     Current-Controlled 2x3-Phase Wye Configuration
                       (continued)




   low dc voltage ripple, approximately 4.5V

   only positive currents between rectifier and capacitance
                                             Harmonic Analysis of Current-Controlled
                                                 2x3-Phase Wye Configuration

                                                    Input Current FFT
                         12




                         10
                                                                                                      Input Current FFT Results:
Harmonic Magnitude (A)




                          8


                                                                                                         dominant switching harmonics
                                                                                                           • approx. 11.5A and 9.5A at sidebands of fs
                          6




                          4
                                                                                                           • approx. 6.5A and 6A at sidebands of 2fs
                          2




                          0
                                                                                                         dominant 5th harmonic, approx. 8.2A
                               0   10   20   30     40          50          60   70   80   90   100
                                                          Frequency (kHz)




                                                   DC-Bus Voltage FFT
                          1


                         0.9


                         0.8
                                                                                                      DC Bus Voltage FFT Results:
                         0.7
Harmonic Magnitude (V)




                         0.6


                         0.5
                                                                                                         dominant switching harmonics
                         0.4
                                                                                                           • approx. 0.65V and 0.5V at sidebands of fs
                         0.3


                         0.2
                                                                                                           • approx. 0.85V at 2fs
                         0.1


                          0
                               0   10   20    30     40         50          60   70   80   90   100
                                                          Frequency (kHz)
Current-Controlled 6-Phase Independent Configuration


   Matlab Simulink Schematic




                                Schematic of IGBT H-Bridge
Current-Controlled 6-Phase Independent Configuration
                     (continued)



 Schematic of PWM Generator
   (current-control scheme)




                              current-control waveforms (phase A)
Current-Controlled 6-Phase Independent Configuration
                     (continued)




                                          Schematic of IGBT H-Bridge




  modulation & gating signals (phase A)
Current-Controlled 6-Phase Independent Configuration
                     (continued)




 device currents (phase A H-bridge)   source voltage and current waveforms
Current-Controlled 6-Phase Independent Configuration
                     (continued)




   dc bus voltage lowered by   3

   increased dc voltage ripple, approximately 6.2V

   only positive currents between rectifier and capacitance
                                             Harmonic Analysis of Current-Controlled
                                               6-Phase Independent Configuration

                                                    Input Current FFT
                         25

                                                                                                      Input Current FFT Results:
                         20




                                                                                                         3rd harmonic, approx. 22A
Harmonic Magnitude (A)




                         15


                                                                                                         5th harmonic, approx. 10A
                         10




                          5
                                                                                                         dominant switching harmonics,
                          0
                                                                                                          approximately 8.5A at sidebands of 2fs
                               0   10   20    30    40          50          60   70   80   90   100
                                                          Frequency (kHz)




                                                   DC Bus Voltage FFT
                          2


                         1.8


                         1.6                                                                          DC Bus Voltage FFT Results:
                         1.4
Harmonic Magnitude (V)




                         1.2


                          1                                                                              dominant switching harmonic,
                         0.8
                                                                                                          approximately 1.9V at 2fs
                         0.6


                         0.4


                         0.2


                          0
                               0   10   20    30     40         50          60   70   80   90   100
                                                          Frequency (kHz)
                                                                              Effects of Offset Gating

                                                   Input Current FFT
                                                                                                                                                       Input Current FFT
                         50
                                                                                                                             25

                         45


                         40
                                                                                                                             20

                         35
Harmonic Magnitude (A)




                                                                                                    Harmonic Magnitude (A)
                         30
                                                                                                                             15

                         25


                         20
                                                                                                                             10

                         15


                         10                                                                                                   5

                          5


                          0                                                                                                   0
                               0   10   20   30   40         50          60    70   80   90   100                                  0   10   20   30    40          50          60   70   80   90   100
                                                       Frequency (kHz)                                                                                       Frequency (kHz)

                                                  DC Bus Voltage FFT
                                                                                                                                                      DC Bus Voltage FFT
                          2
                                                                                                                              2

                         1.8
                                                                                                                             1.8

                         1.6
                                                                                                                             1.6

                         1.4
                                                                                                                             1.4
Harmonic Magnitude (V)




                                                                                                    Harmonic Magnitude (V)
                         1.2
                                                                                                                             1.2

                          1
                                                                                                                              1

                         0.8
                                                                                                                             0.8

                         0.6                                                                                                 0.6

                         0.4                                                                                                 0.4

                         0.2                                                                                                 0.2

                          0                                                                                                   0
                               0   10   20   30   40         50          60    70   80   90   100                                  0   10   20   30     40         50          60   70   80   90   100
                                                       Frequency (kHz)                                                                                       Frequency (kHz)


                                             non-offset gating                                                                                        offset gating
                          Hardware Implementation

                                                                                                                           Powerex Module
   Planned hardware testing configurations:                                                                              (two rectifier legs)

     • 2x3-phase wye
     • 3-phase independent                                                                                         Ia

                                                                                                                   Ib



                                                                                                                         x4
                                                                                           3-Phase
                                                                                                                               Powerex Module
                                                                                         Transformer
                                                                                                                              (two rectifier legs)
   Hardware representation:
                                                               3-Phase
                                                                                                                   Ic

     •
                                                               120 kVA
         Generator = 120 kVA programmable source            Programmable                                           Id


          • two 3-phase transformers for
                                                                Source


                                                                                                                           x4
                                                                                           3-Phase
                2x3-phase wye configuration                                              Transformer
                                                                                                                                 Powerex Module
                                                                                                                                (two rectifier legs)



     •   Rectifier = Powerex configurable IGBT            (Representing 2x3-Phase Wye Generator)                   Ie

                                                                                                                   If
                      H-bridge assemblies (4 available)
          • 3300µF capacitance by default
                                                                                   Gating Signals
                                                            Opal-RT HILbox            x4
                                                            Rapid Prototyper          x4                                      x4
                                                          (Rectifier Controller)      x4


     •   Control = Opal-RT HIL Rapid Prototyping System                                                      Idc
                                                                                                                            Powerex Module
                                                                                                                        (used as capacitor bank)

                                                                                                       +


     •   Load = 20kW fan-cooled resistive bank                               20 kW
                                                                            Resisitive
                                                                              Load
                                                                                                       Vdc                                       3300µF


                                                                                                        -
                   Hardware Implementation (continued)




                               Powerex H-bridge Assembly




120 kVA Programmable Source
                                                             Rectifier Bridge

                              Opal-RT HIL Rapid Prototyper
Test Setup
                            Experimental Results


   switching frequency = 10kHz, dead time = 5µs

   simple voltage control used in initial testing

   desired full load testing
     • 20kW load at 600V dc
     • phase voltage = 219.4V rms (380VLL rms) at 708Hz
   2x3-phase wye testing abandoned due to diode failures on two bridges
     • BAE Systems desired operation without snubber circuits
     • caused by voltage spikes due to di/dt at IGBT turn off
   continued with 3-phase wye testing
     • transformers and damaged bridges removed
     • dead time increased to 10µs
   voltage and frequency slowly ramped up
     • highest level achieved = phase voltage 140V rms at 550 Hz
                 Experimental Results (continued)




Phase A Voltage & Gating Signals            Input Current Waveforms

   proper gating signals produced by the      sinusoidal currents drawn
    control-scheme                             high reactive power
   voltage waveform shows PWM effects            • no phase correction in simple
    due to source impedance                          voltage control
Experimental Results (continued)



                        DC Bus Voltage and Current
                           Waveforms

                           Ch. 1 – dc bus voltage (313.4V)

                           Ch. 2 – rectifier output current
                                   (before capacitance)

                           Ch. 3 – dc load current (18.6A)
                                   (after capacitance)

                           5.85 kW dissipated
                                    Conclusions


   excellent dc bus voltage regulation in all active rectifier simulations
     • less than 6.5V ripple with current-control
   current control operation produced excellent input current waveforms
     • sinusoidal currents with low THD
   H-Bridge configurations benefit from offset gating
     • eliminated harmonics at odd multiples of fs
     • little influence on other harmonic magnitudes
   hardware testing results show promise of high performance
     • modulation produces sinusoidal current waveforms
     • further improvement with current control
     • snubber circuits needed for further testing
Questions?

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:5
posted:9/2/2011
language:English
pages:50