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KEA128BLDCRD Sensor-less BLDC

Question asked by Carlos Hidalgo on Aug 15, 2016
Latest reply on Aug 31, 2016 by Carlos Hidalgo

I have the KEA128BLDCRD demo board.  No problems getting it up and running with the included motor. 

I am trying to drive a custom sensor-less BLDC motor - 3 phase, 10 magnetic poles.  I cannot get it to start reliably.  Regardless of how I set the various parameters in the Freemaster app, the best I have been able to do is to get it to start one time in 5 or so.  If I push-start the motor, it runs fine, but I can't get it through the open-loop start-up process.  More often than not, it runs in the opposite direction slowly until a stall error is generated.

(The motor runs fine on a Turnigy PLUSH-80A controller.)

 

How do I determine the various parameters to get it to start reliably?  I have been through the "Sensorless BLDC Control on Kinetis KV" app note (AN5263), the only one I could find with any details on how to tune the system, but the only instructions I find there are in the flow chart:

     "Motor starts and smoothly switches to closed loop:  False

          Sensorless tab:

          - Tune Integ thr corr constant

          - click update"

I need a little more help than that...

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