Problem in Torque Control with Hall StartUp

[joãopaulo]

I'm developing an E-Bike based on KV31F and KMS and I intend to use Torque control with Hall StartUp, but looks like that when the control changes from hall to torque control the three fases of the motor are shorted, because the bicycle wheel stops abruptly, however the system don't show any fault. What could be the cause of this behavior?

Thanks.

[linestream-adam]

Interesting.  There was a bug in the latest KMS with respect to running torque control after hall startup.  The updated file has been posted in this post (see the bottom of the thread): https://community.nxp.com/thread/469770 

I would be curious to hear if you have the same issue after trying with the updated file.

[joãopaulo]

I work with the guy of the other post.

The problem now isn't reach the rated speed, the problem is that if I set more that 3A for the current mode the motor stops like the three fases were shorted, and seems that higher the current the sooner the motor stops.

If you could support me with some urgency I'd be greatful.

Thanks.

[linestream-adam]

Gotcha.  I started looking into why the phases shorted, and nothing is jumping out at me as to why that would be happening.  Is the power supply dipping such that the MCU is browning out?  KMS will tell you if the MCU resets.  If you don't have KMS connected, make sure that commTimeOutEnabled in main.c is set to false.

[PedroCastro]

Hi Adam,

I am working in the same project as João. The MCU does not reset and I don't use the commTimeOutEnabled anymore. It looks to me that when a higher current is set a higher speed is reached faster. When the bikes wheels spins withoud a load, the motor stall even faster. One possible solution would be to enter in COAST mode when in higher speeds but I am not sure if it is possible to go from BRAKE_COAST to RUN_CURRENT withou going through IDLE. If is is in IDLE, the system must be below FOCLowSpeed, correct? However it is not case. Do you have any ideas?

[PedroCastro · Accepted solution]

the problem was solved using the file attached by AdamReynolds‌ in this post:

https://community.nxp.com/thread/471190 

[joãopaulo]

Thanks very much for the great support Adam Reynolds!