TMS320F28379D: PWM for a Single-Phase H Bridge Inverter

Modar JOMAA

Part Number: TMS320F28379D

Hello,

I want to use TMS320F28379D LaunchPad to generate high frequency PWM for my single-phase H bridge inverter.

Do you think it is possible to generate a PWM with frequency of 1.5MHz for th carrier signal and 150kHz sine wave for the duty cycle with good resolution?

I've tried to do so using DSP Sine Wave block in Simulink and the maximum resolution I've got for the duty cycle was 20 points per cycle for 20kHz (maximum sampling time was 25us).

Thanks in advance for your help

over 3 years ago

0 Marlyn Rosales Castaneda20 over 3 years ago

TI__Mastermind 24800 points

Hi MJ,

Thank you for your question. I will get back to you tomorrow with an answer.

Best Regards,

Marlyn

0 Marlyn Rosales Castaneda20 over 3 years ago in reply to Marlyn Rosales Castaneda20

TI__Mastermind 24800 points

Hi MJ,

If you want the PWM to generate a 1.5MHz frequency, then you will have 66 counts (Max EPWMCLK = 100MHz)

100MHz/1.5MHz = ~66

For the sine wave of 150kHz -> 1.5MHz/150kHz =10

"Good resolution" will depend on your system requirements, but from a F28379D perspective that is the best it would be able to do.

Best Regards,

Marlyn

0 Modar JOMAA over 3 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 10 points

Hi Marlyn,

Thank you for your answer.
Unfortunately, I did't get it. You mean that I'll get 10 counts for the 150kHz sine wave duty cycle?

Best Regards

0 Modar JOMAA over 3 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 10 points

Marlyn Rosales Castaneda20 said:
For the sine wave of 150kHz -> 1.5MHz/150kHz =10

I think you got me wrong. Actually I was talking about the resolution of the reference signal (Sine Wave Duty Cycle).

The point I want to be sure about is if the minimun sampling time of this LaunchPad is 25us as I mentionned above.

Thanks in advance for your answer

0 Nima Eskandari over 3 years ago in reply to Modar JOMAA

TI__Guru 52040 points

Your EPWM resolution is set by the EPWMCLK frequency which can go up to 100MHz.

Depending on your TBPRD, you get only so many usable bits in your TBCTR. So your carrier EPWM TBPRD will affect this.

Your SINE wave you are trying to recreate has a frequency, the ratio between that and your carrier EPWM frequency (TBPRD) will determine how many points you get to recreate your sine wave.

Nima

0 Modar JOMAA over 3 years ago in reply to Nima Eskandari

Prodigy 10 points

Thanks for your answer.

Actually I'm talking about the resolution of the reference signal (Sine Wave Duty Cycle) that i feed to the EPWM block in Simulink or Plecs. Or even when write your own code in Code Composer, the sine wave that you compare to a triangular wave to create your PWM commande, would it be at a frequency of 120kHz and have good resolution? Because I'v tried and I couldn't

Best regards