Motor spins under load in one direction and not in reverse direction

[STuser2]

I have two issues 

Project details:

a. Custom board.

b. MCSDK 6.2.0, FOC, 15HKz , 3 shunt topology , BLDC motor,

c. Motor pilot not configured

Issue1- I have calculated the Hall placement angle as mentioned in the documentation in one direction (clockwise). The motor smoothly starts also under loaded conditions, there are no issues. But when i try to spin in reverse direction with negative Iq under the same load it does not start. 

I plotted Ia, I b using cube monitor

Motor does not start in reverse direction.

Motor runs smoothly without problem in forward direction. How do i debug the issue?

Issue2: Very much related to the above to find the root cause i have tried under no load in another setup using another motor

I have followed hall placement angle procedure in one direction (clockwise) and i was successful in running the motor in no load conditions in both directions with +Iq, -Iq. Placement angle was around 60Degress

But if i followed the same procedure to find the placement angle in anticlockwise direction, i found out from oscilloscope images, i have to swap two hall signals and the placement angle to be changed to 120degrees, I have done both but the motor does not run in either direction.  

[STuser2]

2nd Issue i was able to resolve when i carefully read the documentation, there was the term direction assumed to be positive which i was not clear, now i understood and got it working in both directions.

I need to validate on the 1st issue i hope there will not be any initial torque generation issues in either forward and reverse direction generated from MCSDK software, i will verify and update. 

[cedric H]

Hello @STuser2 ,

What is your MCU ?

If it is not a cortex M0/M0+ CPU based, then you should be able to run the profiler.

If you configure the primary sensor with STO-PLL and auxiliary sensor with Hall-sensors, it will profile the hall sensor for you too. This config is fully described in the User Manual -> "Motor Profiler Application Note"

Kind Regards

Cedric

[STuser2]

My controller is STM32G4RBT6, i have never used the profiler may be i will start doing it is custom board, i will start looking into profiler on priority.

[STuser2]

I have gone through the documentation i am trying to setup the motor profiler for my custom board but it may take some time for me to understand and setup. But when i see the documentation

it mentions that the motor will run in both directions and i can see positive rotation angle and negative rotation angle and then the placement electrical angle which is different 

Positive rotation angle -56Degrees

Negative rotation angle -67Degrees

Placement electrical angle 298Degrees

But when i do the manual method mentioned in the document it is not that detailed 

I have tried different hall placement angles within the range of +- of actual value but the performance is always better in only one direction. It has something to do with hardware or software?

[cedric H]

Hello,

It has something to do with the quality of your motor.

If you need to spin your motor in both directions you can take the 298 Degrees value which is the average of the Positive rotation and negative rotation.

If the control is not accurate enough with this average value, you can always change dynamically the placement depending on the motor direction.

Regards

Cedric