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Start-up failure, MC_START_UP fault flag getting set sometimes.

Jim Frederick_2
Associate III
Posted on April 12, 2018 at 23:49

Using the MCSDK 5.0.1, I can startup and run a BLDC motor most of the time. About 10% of the time, I get a Start-up failure and each time I can see from the Motor Control Workbench GUI that the speed has reached the desired target of 1100 RPM but the Start-up failure occurs anyway. Debugging the generated firmware, I can see RUC_Exec (RevUp control) getting called and returning false which causes the MC_START_UP fault flag to be set. About 90% of the time, ramp-up succeeds and transitions to FOC mode.

I think RUC_Exec is mistaken about the start-up fault because the monitored speed read-back is at the desired target, phase-current is the right frequency and I don't hear the motor assembly missing steps or 'bumping'. The RUC_Exec function appears to be defined in libmc-iar_M4.a which doesn't come with source code, so I can't see why it's returning false. I've requested access to the

http://www.st.com/content/st_com/en/products/embedded-software/mcus-embedded-software/stm32-embedded-software/stm32cube-expansion-packages/x-cube-mcsdk-ful.html

, which I think has source containing RUC_Exec but approval hasn't come thru yet but that's a different issue. 

I'm looking for suggestions to get a more reliable transition from ramp-up to FOC. I've tried adjusting several parameters in Workbench's 'Start-up parameters' page (attached) such as On-the-fly startup, Speed ramp duration, minimum start-up speed etc. 

2 REPLIES 2
Jim Frederick_2
Associate III
Posted on April 19, 2018 at 16:33

Opened ticket

https://my.st.com/tmtrack/tmtrack.dll?IssuePage&RecordId=190190&Template=view&TableId=1011

 for MC_START_UP fault flag.

Opened ticket 

https://my.st.com/tmtrack/tmtrack.dll?IssuePage&RecordId=190842&Template=view&TableId=1011

for X-CUBE-MCSDK-FUL issue.
Laurent Ca...
Lead II

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