VESC 6, astroflight 3215, loosing sync with freewheel

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Rouckie   10 W

10 W
Posts: 93
Joined: Jan 07 2010 8:34am
Location: Belgium

VESC 6, astroflight 3215, loosing sync with freewheel

Post by Rouckie » May 10 2020 5:39pm

Hello,



I have a mountainbike with a astroflight 3215 connected to the rear wheel with a 2 stage reduction. On the intermediate shaft I have a freewheel, the ratio from the motor to this shaft is 4:1.
motor controller is a vesc 6.4
Battery is 12s.
motor kv is 169
Phase current set to 60 A
throttle controls duty cycle


The motor wizard did a good job and the combination works great, except for one big problem.

Problem:

When I reapply throttle after coasting (wheel spinning at 10 - 30 kph. motor stopped, freewheel working.), it happens that the motor starts making a squeezing sound and doesn't move anymore.
I think the controller looses sync
seems only to happen at certain throttle position while reapplying it. low throttle or full throttle seems to work ok. Half throttle seems to give the problem.
squeezing sound continues until I disconnect the battery


What I think happens:

The motor spins up
when the motor speed matches the wheel speed, the freewheel engages abruptly and causes a big torque ripple.
controller looses sync


Is this a known issue?

Can I tweak some parameters to solve this problem?



thank you!



Roel

Pedrodemio   100 W

100 W
Posts: 112
Joined: Jun 30 2015 8:38pm
Location: Brazil

Re: VESC 6, astroflight 3215, loosing sync with freewheel

Post by Pedrodemio » May 11 2020 1:46pm

You shouldn't use duty cycle mode on VESC since it doesn't have free wheel, when you release the throttle it starts to brake since the duty cycle you want is now 0%

Try using current no reverse with brake

Rouckie   10 W

10 W
Posts: 93
Joined: Jan 07 2010 8:34am
Location: Belgium

Re: VESC 6, astroflight 3215, loosing sync with freewheel

Post by Rouckie » May 11 2020 2:14pm

I belive the problem occurs when re-applying throttle, not when closing the throttle.
Anyway, I will try your suggestion and post the result.

Thank you

Rouckie   10 W

10 W
Posts: 93
Joined: Jan 07 2010 8:34am
Location: Belgium

Re: VESC 6, astroflight 3215, loosing sync with freewheel

Post by Rouckie » May 13 2020 2:13pm

Hello,

just to let you know that the problem seems to be solved. However, I did only test for a short time, and also limited the power. Tomorrow I will do some more testing and certainly in the weekend.

thanks

Rouckie   10 W

10 W
Posts: 93
Joined: Jan 07 2010 8:34am
Location: Belgium

Re: VESC 6, astroflight 3215, loosing sync with freewheel

Post by Rouckie » May 15 2020 3:55am

Did some more testing on full power. Problem did not occur once.

Seems solved. Thanks @ Pedrodemio !!

Pedrodemio   100 W

100 W
Posts: 112
Joined: Jun 30 2015 8:38pm
Location: Brazil

Re: VESC 6, astroflight 3215, loosing sync with freewheel

Post by Pedrodemio » May 15 2020 8:17am

Glad it's solved, the duty cycle mode on the VESC behaves completely different than what most people are used to on other ESCs

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