Cutting 5v power to the halls means they shouldn't be able to provide readable signals to the controller, so after that, it depends on the specific controller.
If it's sensorless-capable, it will probably still do regen, though it may behave differently (for instance, the Grinfineons like this use trapezoidal drive instead of sinewave when the halls are not readable, so regen operates differently too).
If the controller is sensored-only, then if the halls are not readable, the controller will usually shutdown to prevent damage to motor or controller. This should also prevent regen from working, because the controller is in a fault state and shouldn't respond to any control input either. But it does depend on the specific controller design.
But if your whole purpose is to prevent regen, then simply don't engage the ebrake.
If you have ebrake switches in your brake handles and have to use the mechanical brakes, just put an override switch in series with this for any time you don't want regen to engage while you're braking mechanically. If your switches are the type that turn on (short) when the lever is pulled, use a NO (normally open) override switch, so that unless it's engaged, it is open, if it is a momentary type switch. If it's a toggle with only one contact set, then you don't need to worry about NC vs NO, only which way you mount the switch so the toggle is in the position you prefer for "on" vs "off".
Unless your controller is programmed to do "slip regen" where any motor speed in excess of that which should happen from the present throttle setting will cause the controller to try to brake the motor until it slows to the speed the throttle is demanding, then simply not engaging the ebrake will prevent the controller from performing regen.
If you are in a situation where a downhill speed is greater than that which the motor can create at the present battery voltage, then even if the controller is not active (or even "on"), but is still connected to the battery, then it will act as a rectifier and still perform regenerative braking--but it is no longer controlled braking, it is simply current flow from the higher voltage at the motor/controller to the lower voltage of the battery, which places drag on the motor and heats it and the entire current path from it to the cells in the battery up, by however much current flows.
The only way to prevent *that* situation is to electrically disconnect the controller from the battery.
Note that in this situation, there is no load on this generated voltage, and it can climb rapidly beyond the point the controller's FETs can handle it, unless they are rated far above the normal battery voltage. This will blow up the controller, or at best damage the FETs or the controller's LVPS (that makes the 5v, 12v, etc inside) so they no longer operate correctly.
You can calculate the approximate voltage the motor will generate if you know it's kV and the speed it will spin at, worst case. If you don't know the kV you can guesstimate it. Take the speed the motor spins at, unloaded, at max throttle on your full battery. Divide the volts by the speed. Then take the speed the motor will spin at at the maximum downhill speed you might ever achieve, and multiply that by the result. That gives you an approximation of the voltage the motor could output under that condition.
If the controller, and anything else connected to the controller's battery wires (other than the battery that isn't connected in this scenario), are not rated for *at least* that voltage, preferably higher, damage may occur.
In some scenarios it is much better to just let this kind of generator braking occur to the battery, because the consequences are easier to deal with than those without it connected.
E-HP said:
I guess I'll scrap my idea. I was trying to think of a way to disable regen temporarily on the fly, specifically for when the motor is hot already from climbing, and want to avoid additional heat from regen when descending. However, I just thought of something I can try today...maybe I just hit the power button.
E-HP said:
I'm bouncing a few ideas around in my head, and had a couple things that I was wondering about.
- With a sensored motor and regen capable sensored controller, does the controller need the hall sensor signals to provide regen?
Not necessarily related:
- With a sensored motor and controller, if you disconnect the 5V wire between the controller and motor, will that stop any phase current going to the motor?