Generate HRPWM with F28335

Boxue Hu

Hi.

I am right now using F28335 to generate 4 PWM signals for a phase shift power converter. I want to have a precise control on the phase shift time and also the deadtime.

From the HRPWM reference guide, I know that I need to use BEP for the HR edge mode. But in the reference guide for HRPWM and ePWM, there is no clear explanation on how the BEP mode really works.

In the BEP mode, should I use TBPHSHR and CMPAHR together to achieve high resolution on both falling and rising edges? Can someone give me some sample code on this?

Thanks

Boxue

I have read the sample codes from the controsuite. It seems that they are all dealing with FEP or REP mode.

over 9 years ago

0 Subrahmanya over 9 years ago

TI__Mastermind 24095 points

Boxue,
in BEP mode delay is applied to both edges and hence you should use this mode for phase shift. You can you TBPHSHR for the phase shift and make sure the smae is selected in HRCNFG register.
-Bharathi

0 Boxue Hu over 9 years ago in reply to Subrahmanya

Prodigy 70 points

Hi.

I am still not clear how high resolution is achieved at both edges. If I use TBPHSHR to achieve fine phase shift time (at the rising edge of PWM2), then can I also achieve high resolution at the falling edge of PWM2 (the third red dash line)?

0 Subrahmanya over 9 years ago in reply to Boxue Hu

TI__Mastermind 24095 points

Yes. In this case same delay (TBPHSHR) is applied to both edges since you are using BEP mode.
If you configure it as rising edge or falling edge mode - then you can achieve duty cycle control.
In this mode (BEP) - it's only phase shift.-Bharathi.

0 Boxue Hu over 9 years ago in reply to Subrahmanya

Prodigy 70 points

So. The two edges related to TBPHSHR are the falling edge of PWM1 and rising edge of PWM2. So it is impossible for DSP 28225 to have high resolution phase shift and HR duty ratio at the same time, is it correct?

0 Subrahmanya over 9 years ago in reply to Boxue Hu

TI__Mastermind 24095 points

Not on F28335. The newer devices which have EPWM/HRPWm type >1 like F2802x, 3x, F28377x etc. support this feature. You can attain both HR phase and duty control.

0 Boxue Hu over 9 years ago in reply to Subrahmanya

Prodigy 70 points

Thank you. I see.

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Generate HRPWM with F28335