LAUNCHXL-F2800137: Level 4: Motor overcurrent fault at high speed

Hi Rahul,

What is the value of the current control loop bandwidth?

Thanks,

Jiaxin

Hello Jiaxin, 

I'm not aware of how to calculate it. Could you please advise how do I calculate and set it correctly? (both hardware and software)

Thanks. 

Hi Rahul,

You can tune the bandwidth "objUser->BWc_rps" in function USER_setMotor1Params() in "user_mtr.c". The bandwidth sets the Kp, Ki of the current control loop and you can find this in function: setupControllers() in "motor_common.c".

Thanks,

Jiaxin

Hello Jiaxin, 

I have been trying to tune bandwidth without any luck till now. 

objUser->BWc_rps = MATH_TWO_PI * (float32_t)200.0f;

firstly, I tried increasing the factor 200.0f to 400 but I got same issue, before realizing I should be reducing the bandwidth. 

When I reduce this factor till 10, I still see over-current failure. When the over-current fault happens, power supply current consumption is still at 1.3A. 

Motor over-current is set to 10A and max current is set to 5A. I'm attaching user_mtr1.h here. 

Could you please advise what is going wrong here? 

Thanks. 

2627.user_mtr1.h

Hi Rahul,

What is the hardware you are testing with? Do you have the oscilloscope screenshot during the overcurrent transient?

Thanks,

Jiaxin

Hello Jiaxin, 

I solved this issue by using motor parameters identified from LAB02C with F28069M kit (Motor ID for low inductance PMSM). 

F2800137 was identifying motor inductance as 24uH whereas actual value is around 8.5uH. 

I have one question, how do we decide on bandwidth delta? Currently it is default set as 20.0f. 

objUser->BWdelta = (float32_t)20.0f;

Thanks. 

Thanks Jiaxin for your support.