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Highly dependable way of stopping PWM generation.

Szilard Lovas
Expert 1425 points

Hi Guys,

I'd like to shut down a  high voltage / high current IGBT inverter output in highly dependable way.

The IGBT driver controlled by a 3 phase ePWM peripherial and it has an ENABLE/RESET input, but I don't want to rely on just one mechanism so I 'd like to switch off the PWM generation next to using IGBT ENABLE signal. The safe state is low or highz.

Options:

- Continuous Software Force on PWM output A and B low.
- Stop PWM by software Tripzone and force output to low or highz.
- Configure PWM multiplexer to GPIO input (highz).
- Configure PWM multiplexer to GPIO output low.

What is your opinion, which option (or combination of options) is the most reliable way for disabling PWM output?

Thank you, regards: Szilárd

  • 0
    TI__Guru 72500 points
    I won't pretend to be an expert in ePWM, but you might consider setting the CBC (cycle by cycle) flag in the TZFRC (trip zone force) register to force the ePWMx pins as outputs low. Then use the input function of a shared input to read and verify that the signal did indeed go low. As a backup to the backup you could use the pinmux to change any pin that did not go low to a GPIO and force it low. The pin mux logic is closer to the pin than the ePWM logic.
  • 0 in reply to Bob Crosby
    Expert 1425 points
    Hi Bob,
    Thank you for your recommendation!
    Regards, Szilárd