Configuring Votol em200 controler to work with a small bldc motor

Jeff23spl

100 µW
Joined
May 22, 2023
Messages
7
Location
Quebec
Hello

Story:
Last year i moded a brushed 500w PB batteries kick scooter into a lithium bldc ride.
I bought a cheap 48v 2000w kit from Vevor. (I think it is same as Kunway.)
I made a 14s6p pack of 18650 3Ah 2.5c cells and connected everything to work fine with it including hall sensors.

Acceleration results are geat (A lot faster and torquier than before) but cruising and low speed riding isn't. The controler feel like if it is set for speed target rather than targetting torque. (Small throttle input makes heavy acceleration to reach that low speed as quick as possible rather than reducing torque.)
I tryied the 3 speed switches, 2-3 different throttle and even adding resistors to find a way to make it smoother without any success.
The cheap controler is similar to the one of low cost e-bike kit and doesn't look programmable. (Square aluminium box with fet bolted on the side and a bunch of wires in just 1 end).

I ended up looking for a replacement controler that can be programmed for a smoother ride and i would also like to have flux weakening to gain top end speed without reducing low end torque to climb a hill.
Space is limited but i could fit a EM50-4 in there.
Why Votol? because i have a EM200 in hands for another project and i'm assuming if i can make it work with the EM200, i can buy a EM-50-4 without any risk of non compatibility. (The EM200 is from a kit with a QS138 V3 that i bought for a later E-motorcycle project into a Yamaha 1977 frame...)

The EM200 look to be factory set to fit the QS138 V3 motor and that combo worked great when tested unloaded.
-I lowered the voltage setting on the controller to fit my 14S pack and let everything else as per factory. (I don't want to lose the match for the QS138)
-I successfully paired the hall sensors of the small veyvor motor to the EM200 controller. (Color was almost matching so it was easy)
-I temporary connected the controls of the E-motorcycle to test the controler on the kick scooter. (Motor is mid size chain driven to the rear wheel. Wheel is up in the air for testing purpose)
When i slowly increase throtle it start correctly so i expect phase angles and polarity is ok but it start to jerk, when i push the throttle further.
I measured the RPM and it reach faster speed at part throtle than it was going on it's own controler before reaching the point where it start to jerk. This is driving me to believe that flux weakening might be the problem.

Question:
Information on Votol controlers seem hard to find. Just to figure out the wiring diagram took me some time and the website manual is not giving much infos about it. I could try some values without any clue but i don't even know if i need to reduce or increase the number to limit the flux weakening.
Is anyone here more familiar with those controlers and could help me understand how flux weakening parameters works ?

Can the fact that the controler is 4-5time more powerfull than my motor make the readigs to go nuts because the signal isn't strong enough ?

Can the test with the wheel in the air affect the results ? The load is small and chain backlash may return an oscillating current feedback...? I'm afraid to try it on the ground because when it start to jerk, it keep going when i let off the throtle, i have to stop the controler to stop it.

thanks
 

amberwolf

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Aug 17, 2009
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Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion
A torque (current) -modulating throttle controller will essentially go full speed without a load even at a tiny amount of throttle, because it takes very little torque (current) for it to do this (usually an amp or two, or even less).

To really see what the throttle control is setup like you have to ride it, or setup something like a dyno (dynamometer), or one of those bike trainers (like the ones that tell you how much power you are putting out), to "ride" it on stationary and put the load on the wheel so you can tell how the throttle "feels", etc.


Most controllers (pretty much nearly all the cheap ones in kits) are speed-modulating (really they modulate the duty cycle of the PWM to the motor, which modulates the voltage, which in turn modulates the speed), so the throttle behaves about the same with or without a load.
 

Jeff23spl

100 µW
Joined
May 22, 2023
Messages
7
Location
Quebec
A torque (current) -....
Thank you for explaining but the initial problem driving me to change controler was happening under load (with 140pound on the scooter) The tests run unloaded was only when i was trying to configure the Votol 200amps controler on a 40a motor

Since you spend time to talk about it, i will try to better explain what i was trying to say:
I agree with you that controler power stage will modulate the output signals to adjust the average voltage seen by the motor and doing this, affect the resulting current and speed (RPM) (I do work with industrial variable frequency drives having similar caractéristics)
But the controler ''brain'' could drive the output level using few differents control strategies.... With industrial VFD i have options to select it but not with my Veyvor one.
The best strategy for mobile use, is probably to use torque control (amps). The throttle input send a signal to say how much current you want to use and motor reach a speed rpm reverse proportional of the load it need to drive. Light load = greater accel and speed vs the opposite with more load. Exactly like the carburator plate on a thermal engine...
Differently, a machine or tool, would need a different strategy where we want to track a fixed speed. The signal input give a specific motor rpm target and the controler automatiquely change voltage/current to reach and keep that target rpm. if rpm decrease controler rise voltage and the opposite if rpm increase....
When i try to softly ride that Veyvor controler compared to my other rides (2 brushed kick scooters and a bldc geared hub ebike) this veyvor have a totally different reaction feeling. It seem to act like the machine tool explained above by giving the full torque regardless of throtle input and settle down when motor get up to speed. Instead of slowly accelerate with a small input signal like a torque control should do.
It is hard to explain but i think the combo kit i got has been more designed for a machine tool than a kickscooter...This is the main reason why i want to replace it.

I was planing to try an E-bike controler to see if the program would react the same since i have an ebike with similar low cost square box controler that run very smooth instead of the Veyvor kit. But i think about the option to add flux weakening to my kickscooter to gain speed at the same time and ended up looking at Votol EM-50-4

My questions for this post was more about: how to configure Votol parameters to run a Veyvor motor. As explained, it is when i try to run the motor with my EM200 that it start to oscillate and i would like to stabilise it.
 

Jeff23spl

100 µW
Joined
May 22, 2023
Messages
7
Location
Quebec
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