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Problem with motor startup - only 1/2 of pole positions work in FOC

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Knapers
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Joined: 2019-05-29 18:51
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Problem with motor startup - only 1/2 of pole positions work in FOC

Hi everybody, 

this is my first post here, but I have been working with VESC's for the last 2 years, building an ebike. Recently, I decided to upgrade to VESC 6.6, as my other two 4.12 VESC's died during driving, and I suspect it was due to bad cooling and old hardware/design.

My problem is as follows: When trying to spin up the motor from standstill only 1/2 of motor positions work. What I mean with that is, I use 14 pole motor, when in stand still, motor tends to stop between magnets - that makes 14 different positions for the motor to stop in. At first I thought this was a configuration problem, so I re-flashed the firmware and set up motor using wizard. Only change is to disable regen braking - set values to 0, and to set lower battery cutoff than actual, to fix performance issues. Motor has hal sensors. I set it up in FOC. 

I discovered this by using VESC UART input as control. Did not attach any other throttle. I was able to spin up the motor without it stuttering using every other position. Its very weird, as in one position the motor spins up perfectly, in the next it stutters around or does not start at all, only lets out an electrical whining sound. In the next after that it works perfectly, in the next one again no luck, and soo on. Weirdly enough, when testing in BLDC mode, there is no such issue. I would prefer to use FOC mode, as it is quieter, but for now I will continue developments using BLDC. Maybe someone knows a solution to this? 

I re-soldered the connections yesterday, as I red it on forums, that this might be happening due to bad connection in one of the phases. It was not the case. 

My set up - Flipsky VESC 6.6 60A in aluminum casing, Flipsky 6354/190KV BLDC motor, 8S 6Ah LiPo (60 C discharge rating).

 

Thanks in advance, would love to understand what causes this issue!

 

edit - reverse does not work at all, either in BDLC and FOC mode