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CCS/TMS320F28379D: Build a hysteresis current controller for the TMS320F28379D

Min Zhang
Intellectual 450 points
Part Number: TMS320F28379D

Tool/software: Code Composer Studio

I need to build a hysteresis current controller for the single phase inverter system. A function generator will provide the reference current signal , to compared with current signal obtained by the LEM current from the device. A analog comparator system will compare with these two signals to produce a complementary PWM signal ( bipolar PWM) to control the inverter. A RL load is connect in the inverter Ac side. The DC side will be connnected to a DC source (30V). My question will be : 

1) for the hysteresis band , how can i set it for this chip, i notice for the comparator subsystem, there is comparator hysteresis control register, i dont know if this will be work or not. 

2) is any application example relevent to this? I have looked at peak current controller examples and others, i didnt find a very near application examples. If anyone have a similar code or examples, could you mention me or share me a near code for me to act as learning material. 

Thank you very much 

  • 0
    TI__Mastermind 28275 points
    Hi Min,

    I'm not familiar with the hysteresis current controller but i don't think that is the hysteresis you are looking for from the cmpss. I'll explain how the cmpss hysteresis works and you can decide if that applies to your application.

    For example, let's assume the comparator has a 0v offset (to make the explanation simple) and the voltage on the negative input is 1.5v. You would expect a comparator trip when the voltage on the positive input is greater than 1.5v and an untrip if it's less than 1.5v.

    So essentially, the trip voltage is "> 1.5v" and the untrip voltage is "< 1.5v". Hysteresis changes this untrip voltage of "<1.5v". For the F2837x, it has 4 levels -> (12, 24, 36, 48) lsb. With a hysteresis of 12lsb (about 10mV with 3.3v reference), your untrip voltage becomes "<1.49v". Hope this clears it up.

    For your second question on how to design the hysteresis current controller, post it separately and the right expert will address it.
  • 0 in reply to Frank Ankapong
    Intellectual 450 points
    Thank you very much