I think you are wise to focus on torque limiting. In my experience, the first components to be damaged in a fault condition are the FETs and their power dissipation depends primarily on current, not motor power. Sean On Wed, Sep 5, 2012 at 1:55 AM, Joe Wronski wr= ote: > On 9/3/2012 6:17 AM, Peter wrote: >> Joe, decide on power or torque limiting (these are 2 different things), = then >> implement it. It is a closed loop so you just do Pwmcontrol =3D (limitin= g)? >> Demand: Demand - LimitingSignal; Cycle by cycle current limiting is anot= her >> thing, and is actually a good idea, but that requires that you see the >> individual current pulses. It may be, that individual pulse current limi= ting is >> all you really want, and that is best done in hardware alone imho. >> > Yeah, I'm going to have to tinker with this a bit to get a feel for it. > I had to look up the difference between torque and power. I'm going to > have to choose torque, since no work will be done if the motor stalls. > I guess I can implement the above logic using a scaling factor k for > LimitingSignal. I can start with k large enough to effectively shut > PWM off when limiting. If that works, I can try decreasing k and > observe the effect. > I finally added the wiring for this (and speed and pedal torque input) > now it's time to see if it works. > I wish I had put more effort into understanding some physics and > whatever math is needed for motor control applications way back when. > Joe W > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .