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HET and SVPWM

Billy Shang
Intellectual 330 points
Other Parts Discussed in Thread: TMS570LS3137

now I use HET to generate SVPWM,i use two het chanels and XOR function to generate Symmetrical SVPWM waveform for A phase,but i have a question there are two SVPWM for A phase(A and NON-A) ,the other waveform is opposite ,the middle level is low ,How can I get the opposite waveform,I want to know about the details.

thank you

  • 0
    TI__Guru 68990 points

    Hi Billy,

    You need to use two more het channels in an XOR configuration to generate the Not-A phase.

    Best way to understand this might be an example.  Please see the attached .zip file.  There are two JPGs showing the HET IDE running this program, one showing the HET IDE registers which you may need to program (XOR register setting and prescale register settings are not default).     Also there is a screenshot of the 3 phases.

    To start the PWM you need to 'poke' a non-zero value into the data field of the first instruction.  If you put a zero back into this field, it also stops the PWM at the end of the current PWM period.   

    You can also poke values into the data fields of "BUFPER"  (period)  BUFDCA (duty cycle phase A),  BUFDCB, BUFDCC,  while the simulation is running and see how the outputs change.    Last the data fields of BUFDBA, BUFDBB, and BUFDBC control the amount of deadband.

    The pin configuration is weird for the simulator but uses pins that are available nicely on the TMS570LS3137 HDK,  and is determined by the equates for PHAHI, PHALO, etc.. at the top of the HET program.   You can change these but you'll also then need to change the XORSHARE register appropriately.

    The default values of the period and duty cycles, deadband, etc are set by the equates 'defper', 'defdca', etc...   These just control the initial values but you can write over them at runtime through the data fields I mentioned above.

    1423.pwm_3phase.zip

    Best Regards,