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CBC ePWM Space Vector Modulation

Karthick Samy
Prodigy 160 points
Other Parts Discussed in Thread: CONTROLSUITE

Hi,


I want to implement the current limiting mechanism for inverter using Analog comparators and cycle by cycle (CBC) Trip Zone events.  The inverter implements Space vector modulation to convert DC to AC.


Is there any application note / some references that defines the usage for CBC feature for current limiting in inverter. I know this is a simple task with Buck or Boost converter where only one switch is involved. But how to deal with inverter?

  • 0
    TI__Mastermind 43730 points
    Karthick,

    You can refer to examples in controlSUITE

    C:\ti\controlSUITE\development_kits\HVMotorCtrl+PfcKit_v2.1\HVACI_Sensorless

    to make sense you will need to look at the schematic of the board and the code, there is protection code in the .c file where we configure all the comparators.

    Depending on which device you are using there may be more optimal implementation, for example in our newer devices there is no need for extra comparator and reference generation outside the chip, everything is integrated on the MCU
  • 0 in reply to Manish Bhardwaj
    Prodigy 160 points
    Manish,

    Thanks for your response. However I have few more questions.

    I am planning to use F28075 new picolo micro controller with 8 internal comparators. I have configured the those comparators and ePWM to trip on fault.
    But I want to have the following configuration.
    1) Inverter shall continue to feed in less current in case of over current fault. This has to be done with CBC trip event.
    2) Space vector modulation is used.
    3) Its not a simple B6 topology, its NPC where turning off of the PWM should follow a sequence.

    I know CBC is very famous in Buck or Boost converters but I want to explore if there is a possibility to extend this functionality to the inverter as well.
  • 0 in reply to Karthick Samy
    TI__Mastermind 43730 points

    Karthick,

    That's a great & smaty choice !! :D

    I will like to understand and help you with the configuration. We may not have some thing ready for NPC but if you can provide more information on what specific things you need from the trip we can suggest configuration of the device.

    1. In light of your info i will suggest looking at configuration under

    C:\ti\controlSUITE\development_kits\TMDSIDDK_v1.0\IDDK_PM_Servo_F2837x,

    HVDMC_Protection Function configures the PWM to trip one shot (i.e. forever) in case of over current . Configuring the comparators is different on F28075 as we have xbars of the device. So have a look at it to understand how to take the comparator trip to the PWM module and trip it in one shot manner.

    To modify it to CBC operation , i will suggest looking at diagram 13-41 www.ti.com/.../spruhm8d.pdf

    Currently the code uses One Shot and hence uses DC_EVT1, for CBC you will need to change it to DC_EVT2

    look at

    " EPwm1Regs.DCACTL.bit.EVT1SRCSEL = DC_EVT1; "

    We have seen engineers use the CBC trip for inverters and motors, specially for startup .

    2. Using space vector will not change trip behavior

    3. What specific sequence of trip do you want? can you share some diagram to enable us to assist you better?