TMS320F28027F: Infrequent glitch in rpm while running at constant rpm and constant load

Prodigy 80 points

Replies: 4

Views: 71

Part Number: TMS320F28027F

I have motorware running on some custom hardware to spin a custom motor with a fan blade on it (So there is a constant load). I have an odd behavior where if I run at a constant rpm (our max speed is 19k rpm) there will be an infrequent glitch in the rpm. This glitch is the rpm dropping significantly, and then recovering back to 19krpm. The issue is this glitch occurs very infrequently and irregularly (I'd say every 30 minutes or so) so we've had a hard time nailing down the root cause. Additionally, if the controller is run for a long enough time I have MOSFETs fail shorted. I'm wondering if this transient rpm "hiccup" is related to these MOSFET failures. 

This hardware is used to spin different motors in different applications, so I know there are aspects of the design that could be improved for this specific motor and speed, but nothing sticks out to me (based on the motorware_selecting_user_variables.xlsx). I've identified this motor with lab2b and the performance otherwise seems good, besides the rpm glitch and MOSFET failures. 

I'm posting because I have a significant amount of successful hours with this hardware and motorware, so I'm unsure where to even begin on this issue. Perhaps it's a PI gain tuning issue, but the fact that it is so infrequent makes me feel like it couldn't be that.

I'll post my user.h in a following message.

Thanks,

Nathan

4 Replies