old KT controller, regen off, but it still does regen.(via throttle)

[marka-ee]

I have an older KT controller and I set the C13 parameter to zero, which is supposed to turn off regen braking. Well, technically it probably did because the brake levers perhaps are not doing regen anymore, but the throttle, when you throttle down, is still doing regen. Does anybody know a way to turn this off also? I want to run this particular controller with a DC-DC boost converter, and the boost converters burn out when they have regen applied to them.

 

[E-HP]

I accidentally found that “feature” on my old KT controller. There appeared to be a voltage range, below the throttle cutoff voltage, but above zero, where this happens, and not noticeable when you just release the throttle. I added a button and trim pot that would keep the voltage above the lower cutoff voltage of this narrow range, and it allowed me to use my throttle to apply variable regen in that region.
Im not sure if this happens on all kt’s, since you're the only other person I’ve heard mentioning it.

motor braking

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[stancecoke]

I have an older KT controller

This simple controllers just set the duty cycle of the PWM with the throttle. The only control is an over current limitation. So it's normal, that you get regen, if the wheel spins faster than the throttle position would allow...
The controller works as an step up converter in this case.

 

[marka-ee]

This simple controllers just set the duty cycle of the PWM with the throttle. The only control is an over current limitation. So it's normal, that you get regen, if the wheel spins faster than the throttle position would allow...
The controller works as an step up converter in this case.

I don't think it's quite that simple. As EHP noted above, as you throttle down, it definitely has a regen braking effect until the last 10% or so of the throttle when it starts freewheeling again. Other controllers I have do not have this braking effect as I throttle down.
In motoring mode, the controller applies current slightly ahead of the rotor magnetic field (positive phase advance) to produce forward torque.
In regen mode, the controller applies current slightly behind the rotor magnetic field (negative phase advance) so that the motor resists motion and generates braking torque — this is what lets it act as a generator.

 

[E-HP]

Could you just add a Schottky diode at the output of the boost converter to protect it?

 

[stancecoke]

I don't think it's quite that simple

It is that simple, just look at the open source code for the Kuntengs, where I've implemented regen. More advanced firmwares (like the open source firmware ) simply will avoid negative currents by tuning the duty cycle that there is no voltage difference between the BEMF and the phase voltage by the PWM....
https://github.com/stancecoke/BMSBa...42cdaf9870063e05f79928cae2/ACAsetPoint.c#L161

 

[marka-ee]

Could you just add a Schottky diode at the output of the boost converter to protect it?

Maybe, but I'm worried about the high impedance going in the reverse direction, and that might cause some kind of problem, essentially, because there's no load for the regen to absorb, if you know what I mean.