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[Solved] Inland BLDC Motor and Sine Controller spins CW faster than CCW?

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EDIT:  i found an answer to my own question, and yes indeed the alignment of the resolver can cause this issue due to phase advance.  One direction will be advanced and rotation in the other will be retarded--just one tooth adjustment on the resolver gear has a significant effect.

Adjusting the resolver involves placing a jumper to cause the current to drive the 3 phases, A=0, B= (-), C= (+).  There are only 3 positions of the rotor which will be somewhat locked in place by application of this winding current pattern, and this is where the resolver zero position must be aligned.  Due to the 6-phase brushless 4-pole tachometer alignment, adjustment of the resolver to 2 of these rotor positions will cause the drive to runaway due to lack of sufficient velocity feedback signal.  At the correct 3rd rotor position the controller will run closed loop, and slight adjustments of the resolver gear teeth can be used to advance the phase for the preferred direction of rotation.  Diagram of resolver gear assembly:




i am having a problem getting this motor and controller to run in the CCW direction.  It runs great in the CW direction--even faster than the commanded set point, but it lags the set point in the CCW direction.  It seems to top-out at a certain speed and won't run any faster even if commanded higher and the velocity error signal is nearly to the rail.

We are driving the spindle on a large lathe using an Inland BRT-4503-3005-B brushless 3-phase 6-pole motor with brushless tach and Harosyn RCX resolver being driven by an Inland BDS1/1-208/50 sinewave motor controller that uses an AD IRDC1730/33 Resolver-to-Digital Converter. 

This controller uses the Industrial Drives Division's proprietary "self-synchronous" digital motor control concept, where the tach signal runs thru an analog mux triggered by the resolver.  The command and tach speed are then summed in a op amp to generate the velocity error signal.  The absolute value of the tach signal and the velocity error are fed into A/D Converters, the outputs of which become the address lines to a torque angle eprom.  The torque angle data is summed with the resolver position to determine the optimum position of the stator magnetic vector for any given speed and load, and this signal becomes the PWM current drive signal for the high voltage output stage.

i have replaced all the power supply capacitors on all the boards and inspected for cracked solder joints, etc.  Everything appears to be working fine, but i can't understand what needs to be adjusted to get it to run properly CCW.  It's as though it runs too fast CW and too slow CCW.

Is there some misalignment of the rotor, tach and resolver with respect to the stator that could be causing this sort of issue? 

The resolver signal is used to generate 3 sinewaves 120 degrees apart and the tach generates 2 cycles per one motor revolution.

i have the data from the torque angle eprom but without knowing how it is used i can't determine if it is good data or may be the culprit.



1 Answer

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Customer discovered the feedback alignment was the issue.  One way to test this during motor startup is to lower overspeed, in case motor runs away, then place drive in TORQUE MODE.  Slowly increase current in the positive direction until motor moves.  When it moves, note speed (including direction) and current.  Stop motor.  Slowly increase NEGATIVE current until the motor moves.  What you are looking for is roughly the same velocity at the same amount of current, and positive current = positive direction and negative current = negative directions.  Velocities should be roughly the same for +/- current.
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