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Hub Motor Gives up while Coasting With No Faults

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vadicus
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Hub Motor Gives up while Coasting With No Faults

When you think you resolved one issue, another one is waiting for you around the corner. :)

Maybe someone experienced this before and can provide some insights. I am testing my custom controller (https://vesc-project.com/node/1477) with a hub motor (qs205). The motor runs fine with or without load if I actively engage accelerator or regen throttles. However, if go to high RPMs, release the throttle and let it coast, the throttle would not respond the next time I engage it. VESC shows no faults. It just silently disables power output. I have to reboot VESC to get it going again. 

This doesn't seem to affect non-hub motors such as inrunners. They don't seem to have this issue. Any ideas as to what's going on here?

district9prawn
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Your controller has some custom firmware and functionality right? Maybe the mcu or a thread is crashing? It's a weird issue.

vadicus
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Nothing too custom in the FW but maybe something is messed up. I have drivers that are controlled by the MCU and overcurrent/overvoltage circuits. It would disable the gate drivers if OV/OC event occurs but it would also signal as a DRV fault to the CPU. I tested and that works well. However, this time, no fault is generated. I would open throttle to 100% and it would run fine as long as I keep the throttle in that position. If I brake with regen from that moment, the throttle would work again fine. So, if I actively accelerate and decelerate, everything is good. It's only if I open the throttle 100%, release it and the let the wheel coast and slow down, the throttle control would be lost from that moment. It would not respond to either of the throttles anymore. VESC Tool does show duty responding accordingly as I twist the throttles, but no power output. I almost  think there gate drivers get turned off. But this doesn't happen on other inrunners and smaller motors. One the hub motor. Very strange.

 

 

NextGen FOC High voltage 144v/34s, 30kw (https://vesc-project.com/node/1477)

district9prawn
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Maybe it is related to how the vesc tracks with bemf?

I experienced a similar problem with the bemf axis decoupling option while messing around with field weakening. It calculates phase bemf using speed * flux linkage. When this was not accurate (say during field weakening) it could lose track and over current fault, sometimes while reengaging the throttle.

 

vadicus
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What's interesting is that there is no fault. it goes full speed, I release the throttle, then re-engage again and no power. The controller is on, the duty cycle moves as I am twist the throttle, just no power. If accelerate and then brake quickly and then accelerate, it would work fine. It's just when going full speed and then releasing the throttle, that's where it stops responding to the throttle. This is on a bike with qs205 hub motor. When I test on a bench with another hub or an inrunner, everything works fine. Maybe the weight of the wheel and created inertia as a result is causing this.

 

 

NextGen FOC High voltage 144v/34s, 30kw (https://vesc-project.com/node/1477)