How to handle Regenerative Braking VEC500 if Battery disconect from controller

[Marfel]

What about regenerative Braking, and the contactor cut off the Battery, how can the controller handle this energy who is produced from the Motor?

for example: you have fully charged your battery, and drive down a hill for about 10minutes, and than the BMS disconnect the Battery from the controller with the Contactor to protect the Batteries, what is in this case?

regards

[Bikemad]

If the battery is already fully charged and there is nowhere else for the regenerative energy to go, then the regen should be disabled to prevent overcharging the battery.

If the controller doesn't do this automatically without opening the contactor, then you could easily wire an additional switch in line with the brake switch so you can manually disable the regenerative braking while the battery is fully charged and re-enable it after the voltage has dropped to a lower level.

It should be possible to electronically switch a relay when the battery voltage reaches a certain level and automatically turn the regen on and off,  or even switch in a dummy load in the same way that a wind generator does if it starts producing too much power when it's very windy.

Alan
 

[Marfel]

Thanks for replay!

the Battery Management System have programmable outputs, so it can opening the contactor if the setted Voltage label is riched,
to prevent the Battery, but this was not the question, im not worry about the Battery, im worry about the Controller.
what happens if regenerative braking is activated, and the BMS opens downhills the contactor to prevent the Battery from overcharging?
i think the controller will blowing up!
If I install the System as Golden Motor Wireing Diagramm for the VEC 500 Controller  it is only a question of a Time if the Controller is blowing up!

regards

[Bikemad]

Do you have a separate BMS controlling the contactor, or are you referring to the battery settings within the controller?

If it is a separate BMS that is opening the contacts in the contactor you should try reducing the "High voltage protection value (V)" until it is ~0.5V lower than the BMS maximum voltage setting as this should allow the controller to disable the regen before the voltage rises too high forcing the BMS to open the contactor to protect the battery.

But before you alter the parameters of the controller, you should make a note the voltage difference between the "High voltage protection value (V)" and the "High voltage protection exit value (V)" before altering them (i.e. difference = 0.5V, 1V, 1.5 or 2V etc.) When you have lowered the "High voltage protection value (V)" you must also lower the "High voltage protection exit value (V)" by the same amount to ensure that the voltage difference remains the same.

It is possible that the controller's high voltage protection may still work even if the battery is disconnected, in which case the controller should be protected against excessive regenerative voltage being produced.

However, if you don't have a separate BMS, and it is actually the controller that is opening the contactor, then the in line switch I suggested fitting might be the easiest way to prevent the battery from being disconnected from the controller by preventing regen while the battery is still fully charged.

I live near the top of a steep hill and use home made LiPo packs without BMS to power my hubmotors, so I would simply disconnect the front brake switch so that I could control my speed and stop at the bottom without overcharging my LiPo pack and just use the rear brake lever for regen braking when I want to.

The newer Vector controllers fitted in the GM hubmotors will not activate the regen if the battery voltage is too high, so I no longer need to worry about unplugging the front brake switch. 

I presumed that the VEC500 would be the same.

Hopefully it will be the same when the required settings are entered.



Alan
 

[Marfel]

Hello Alan thanks for replay!

in my case it is a mini car , with a 10kw BLDC Motor and VEC controller,
i think your sugest with lowering the High Voltage and exit Vaule from the Controller is a good Idea what I can do by Software,
and yes the BMS is controlling the contactor,
if the voltage is more ore lower than the setted value in the BMS, the contactor is opening by an BMS output
But I must do anything in Hardware too, a controller is very expensive for 500A 72V, it must 100% secure
i think it will not often be that the Battery will rise to high, im thinking about to disable permanent to open contactor on the high level, but I will not miss this function for deep discharge


regards