Hello,
I am building a lightweight device-prototype equipped with BLDC motor. For this purpose I have already bought a 75/300a VESC and 15070/S SENSORED 35KV 30kW (for 120V) motor from Alienpowersystem. The next step I must do is buying a 20s (?) BMS, a “small” battery pack (the motor have to work only for few minutes), a charger and a brake resistor I suppose (I am planning to use the motor also for constant (~5 min) braking)... Unfortunately it seems to me a little difficult to find so powerful BMS - especially with brake resistor connection (maybe it’s because I am a mechanical engineer...). Would you please give me some help? What should I buy?
What are you trying to achieve? You want regen braking for slowing down over 5 mins, but the battery is small, so it would turn off when battery reached threshold? I don't think a BMS is required to work the regen, you just need to handle whatever is coming back from the motor and dissipate the energy as heat don't you?
What are you trying to achieve? You want regen braking for slowing down over 5 mins, but the battery is small, so it would turn off when battery reached threshold? I don't think a BMS is required to work the regen, you just need to handle whatever is coming back from the motor and dissipate the energy as heat don't you?
Hello. Thank you for your reply.
The device I am building requires a possibility to generate a constant torque for ~5 min. It should work as a brake as well as a drive. The angular velocity can vary from 0 to 2000 rpm. In the “braking mode” the angular velocity should be 0 rpm when actual shaft torque < braking torque.
After seeing this topic: https://vesc-project.com/node/615 I don’t know if my plan of using break resistor will succeed.
Maybe it would be easier to use BMS and battery pack...
I'm not aware of a solution, sorry. It sounds like you perhaps need a form of active braking from the battery perhaps? I'm not aware of this in VESC, but pretty sure some controllers such as Sevcon offer this, for things like active braking based on if the wheels are moving or not. e.g. a forklift with automatic hold using the motor's torque.