Stuttering at high torque with QS273 and SVMC72150

[⠀⠀⠀]

Hi all,

I have a QS273 with a sabvoton 72150 (150A) and a 72V 40AH battery (150A BMS), while the motor works properly under no or little load when applying full throttle under 20kmph the motor will stutter and most of the time cause an overcurrent error on the controller. The display will stay on and so will the lights so I dont think it is the battery, the same issue also occurs when setting the maximum current to just 100A on the controller. I know that the motor has been repaired in the past using honeywell SS41A hall effect sensors so the phase wiring could be wrong.

Could this be an issue with the phase wiring as unless full throttle is applied under 20kmph the issue does not occur, at maximum speed and full throttle the issue also does not occur.

Thank you everyone.

 

[AGS]

I have a QS205 with a sabvoton 72100 and mine will do the same if I give it full throttle from standstill.

So I have learned to feed the throttle in instead of a full twist so it doesn’t cut out.

 

[dominik h]

I had a QS260 60V5000W with a SVMC72150 in my scooter with 21S100Ah Li-NMC Battery (nominal 77V)
I only had once an overcurrent while I was riding uphill at the limit of the motor. While this trip I had a consumption from over 5kwh for the driven 50km. That equals half an hour with 10kw continious.
The phase wires reached already 180°C and the motor housing was 95°C.
In 12000km this was the only overcurrent error I ever had.
My SVMC72150 took a peak of 175A and a continious current of 165A from the battery, and the controller made his 350A phase current from a standstill , all checked with a calibrated current clamp meter.
Voltage sag was 2.2V at 175A.
Probably your voltage sag is to high and the controller tries to compensate with more current and overshoots his limits.
Before I had installed another SVMC72150 which was spot on with 150bA and also had no overcurrent issues, but I killed this one while playing with the weakening field option as I had also killed a SVMC72260 during a no load weakening field test.

Now I have a QS273 10kW and a Fardriver 721800 with 400bA and 1400pA installed. Now my scooter does not feel underpowered anymore.

 

[AGS]

I suspect in the OP’s and my case the overcurrent trip is the protective phase current setting.

Mine is set at 350 amps and the motor may be trying to pull more than that at a stand still or from low speed on full throttle.

If this is the case then the controller is doing it’s job properly to protect itself and the motor.

I can’t measure mine because I don’t have a clamp meter that can measure instantaneous phase current.

If you have set up your far driver to be able to deliver 1400 amp peak phase current then you probably won’t experience the same problem.

 

[dominik h]

The sabvoton was first changed against a Fardriver ND72680 giving the installed QS260 60V5000W 680A phase current from a standstill and up to to 300A line current.
These motors can all take much more phase current then an SVMC72150 can handle, this is a normal situation for the controller and the controller will limit his output voltage to values that do not let the motor take more then 350A phase current.

I did not check the old motor with the ND721800 but I think it would try to get a lot more then 1000A phase current.

At first I would look at the voltage sag from the battery and if it is high I would reduce line current and try again.
If the error still occurs or there is no big voltage sag I would reduce phase current and try again.