Hi,
I understand that you want a high side switch to be opened not the low side one in a 'EPWM' block from Texas Instruments C2000 add-on.
When using the 'ePWM' module from the Texas Instruments C2000 add-on in MATLAB/Simulink, you have the ability to independently control the high side and low side switches of a half-bridge. To keep the high side switch open while not affecting the low side switch, you can use the 'Action Qualifier' and 'Dead-Band' modules within the 'ePWM' block to configure the desired behavior.
Here are the steps you can follow to configure the 'ePWM' block for an open high side switch without affecting the low side:
- Configure 'ePWM Action-Qualifier' Submodule:
- Set the Action-Qualifier (AQ) submodule to define the desired action for the PWM output A (high side) and B (low side).
- For the high side (ePWMxA), you can set the action to be taken when the counter is at zero (e.g., do nothing or force low) and what action to take when the counter matches the compare value (e.g., do nothing or force low). This will effectively keep the high side switch open.
- For the low side (ePWMxB), configure the AQ submodule to toggle or follow the PWM signal as desired.
- Dead-Band Module Configuration:
- If you're using the Dead-Band module, ensure that it is configured so that it does not interfere with the desired operation of the low side switch. The Dead-Band module is typically used to prevent shoot-through by ensuring there is a delay between the turning off of one switch and the turning on of the other.
- Software Force:
- Use the 'Software Force' feature to force the PWM output to a known state. You mentioned you've already tried using continuous software force, but it affected both ePWM-A and ePWM-B signals.
- Make sure that you are only forcing the state of the high side switch (ePWMxA). The software force register has separate bits for ePWMxA and ePWMxB, so ensure you are not inadvertently forcing both outputs.
- Trip Zones and Events:
- If your configuration uses trip zones or other events that could affect the PWM outputs, ensure that they are set up not to interfere with the low side operation.
I hope this resolves your issue.
Refer to the following MathWorks documentation for more information about TI C2000 Blockset:
