How to 'coast' thru an overvoltage situation using MCSDK

[MRyan.7]

Hello,

We have used your MCSDK successfully in a custom BLDC design and it is working well. We have some conditions however when we are reducing speed on a large inertia and this causes an overvoltage spike. The MCSDK faults on this (we have it set to fault protection) immediately.

However, the behavior we are looking for is that during an overvoltage situation we will turn the low side FETs on and if the overvoltage continues for more than some duration ( 100 msec for example ), then we will go to a fault state. However, if the overvoltage condition rectifies itself in this time frame, we would like to continue back to operating condition.

Before we started to code this methodology, I had a few questions:

1) Is there already a method within the MCSDK that handles this type of situation?

2) Does anyone see a problem with this approach or have a suggestion as to another method?

Thanks!

[Giuseppe Scuderi · Accepted solution]

Hi,

you can introduce a lower threshold in order to prevent to enter in a fault state (less than OVP level) for instance and control the bus voltage value. If the Vbus goes above this threshold you can decide to set to 0 the Iq component or activate a brake. I suggest to add this part of the code in mc_task.c file inside the function TSK_SafetyTask_PWMOFF().

BR

Giuseppe

[MRyan.7]

Thank you Giuseppe.

[Laurent Ca...]

The question has been moved from the "Motor Control Hardware" section to the "STM32 Motor Control" section (the question is about the STM32 MC SDK). 

Best regards