STM32g4 Phase shift Peak Current mode?

[270284440]

Does stm32g4 HRTIM support generate phase shift full bridge PWM with Peak current mode control, including peripherals HRTIM ,DAC,CMPx ?

[Igor Cesko]

Hi 270284440 (Community Member),

According our HRTIM documentation - yes: hardware interconnection (HRTIM, DAC, ADC, COMP, OPAMP) in STM32G4 was improved to support various modes.

Read please https://www.st.com/resource/en/application_note/dm00121475-hrtim-cookbook-stmicroelectronics.pdf (Chapter: A.1.1 Sixth timing unit (Timer F)).

Regards

Igor

[Alex-lab]

Hi,

Unfortunately, I was unable to figure out how any of STM32 MCU can operate under PCMC+PSFB control. PCMC seems to be available only for simple buck-like topologies, but not for phase-shift full bridges. My analysis revealed that if ocref_clr_int had been able to toggle OCxREF signal, such operation would be possible. But in fact it can only reset (clear) the OCxREF, which is not enough for PCMC+PSFB operation. This is indirectly confirmed by absence of any examples or Appnotes on this topic (for stm32). Have I missed something? I would be grateful for any advice.

Best regards,

Alex

[jw-powervamp]

Hi Alex,

Did you ever get this working? I am looking for the same toggle functionality.

Kind regards,

Josh

[Alex-lab]

Hi Josh,

I had to switch to HRTIM. With regular advanced timers it seems to be impossible.

Regards,

Alex

[jw-powervamp]

Hi Alex,

Yes I found the same and have moved to HRTIM. Do you remember how exactly you configured the HRTIM to work for PCMC? I am wondering if there's something I have missed.

I've currently got the Set and Reset sources of my second set of PWMs to be an External Event, driven by a Comparator rising edge output, which is comparing the current waveform against an internal DAC reference signal, triggering the PWMs to swap at the same time once the current crosses the reference.

It's working as expected 99% of the time, but every so often the PWMs toggle twice in quick succession when the comparator output goes high, meaning they remain in the same state. The external event is setup as active high and on rising edge so I cannot see why it would do this. 

Kind regards,

Josh

[Alex-lab]

Hi Josh,

Yes, I experienced the same issue and have not found a solution so far. In VCM which I used previously, if the duty cycle is shorter than critical value, I just shutdown the converter, so the system turns in the period skipping mode.

Here, with PCM as we have no direct access to the timer some extreme values (high or low) result in the behaviour you have mentioned, when instead of a minimal level, output jumps to the maximum... This is of course not suitable for real system operation.

Some of my exercises can be found by googling "PCMC+PSFB on STM32 is it possible?"

Regards,

Alex