Disable PWM

[IkerL]

Hello,

I am using a MPC5744P microcontroller to control a PMSM. I use the PWM outputs to control the motor and I use the Output Enable Register (FlexPWM_OUTEN) to enable or disable the PWM outputs. When I want to enable the PWM outputs I use this command in my software:

FlexPWM_0.OUTEN.R = 0x0FF0;

And when I want to disable the PWM outputs I use this command in my software:

FlexPWM_0.OUTEN.R = 0x0110;

The submodules I use to control the three motor phases are the submodules 1, 2 and 3. I use the submodule 0 to control other semiconductors that are not related with the three motor phases. So, I have the PWM outputs of submodule 0 always enabled.

The control of the motor goes fine but when I want to stop the motor I use the "FlexPWM_0.OUTEN.R = 0x0110;" command and in very few cases we have an overcurrent in the phases of the motor. Am I using correctly the "FlexPWM_0.OUTEN.R = 0x0110;" command to stop the motor control? Must I use other command?

I want to add in this message that when I configure the PWM outputs I configure them as SIUL_PULL_DOWN.

Thanks,

Iker Leunda

[PetrS]

Hi,

if output enable signal is cleared, the output immediately goes to high-Z. So depending external circuitry it can bring some issue. Weak pull down could not help too.

It would be better to put outputs to inactive state, for example using MASK or FAULT logic.

BR, Petr

[IkerL]

Hello Petr,

thank you for your answer. I am using the solution you gave me and I am testing it with a motor. The problem I had, ocurred in very few cases so I have to test it many consecutive days.

However, I have seen with an oscilloscope that putting the pwm outputs to inactive state as you recommended me, the outputs of the pwm go to 0 much faster than clearing the output enable as I did before. So it seems it will go perfect.

Thanks,

Iker Leunda