BLDC drive for electric bike
A friend of mine is working for a manufacturer of electric bikes. They are searching for a developper who can design a controller for a BLDC motor with several new features. I can't talk about the details of the vehicle (it's actually not a bicycle but something similar), here. But I do know that the P2 would be a good candidate for the controller because of its excellent analogue and DSP features (keyword "Goetzel"!).
The requirements for the power electronics are completely different from what I've done so far (see industrial servo controller project). It matches more the universal motor driver board from Parallax: low voltage, high current, hall sensors...
So here are my question:
1. Is it possible to run the BLDC driver in current/torque mode instead of speed/voltage mode? The speed of my vehicle is mainly determined externally (by muscle power, terrain slope or inertia) and I need some sort of "throttle" to control the torque of the motor and therefore acceleration or braking. A speed control algorithm would do the wrong things and result in an irritating behaviour. For example pushing "full throttle" at low speeds or standstill would cause the drive to fault out due to over-current instead of accelerating at max. torque. Or pushing the throttle only a little bit at high speed would decellerate instead of accelerate because the actual speed is above the nominal command.
- I've heared of some problems with the hardware. It's said the boards tend to blow up especially with high power and high-inertia motors. I think Chip said this is caused by some negative voltage problem in the MOSFET drivers but I believe it also could be caused by the somewhat minimalistic current measurement ability. The single shunt resistor in the DC link cannot detect over-current while the windings are free-wheeling. Anyway... is this problem solved?
What is the currect state of the software for the Parallax BLDC board? Can I run it with different motors without risking to burn it? Or should I try it only with the original Hoverboard hub motors?