Quote:
|
Originally Posted by IrisLab
Ah! I didn't know that. That does eliminate that as an option, but I can definitely understand the safety concern there.
I've emailed Paul, and we are discussing his design at the moment to help me understand it better.
If anything comes from that discussion, I'll post it here or another thread.
Thanks!
|
If i understand you correctly, you are trying to build a variable reluctance brake by putting a varaible electrical load across the the terminals of a backdriven motor. There is a way to LEGALLY do this. The speed controllers have a jumper which when enabled, causes them to act as a short circuit and effectively a brake, whenever they are sent a signal inside of their deadband. Well anyway all you have to do, if you want variable braking is to send them a duty cycle modulated signal, that switched from being inside the deadband, to just barely ourside it, but not enough so to make the motors even move. In effect you sortof modulate a PWM signal onto a PWM signal.
As far as mechanically how well this works, I am very skeptical. With motors this size the brakign effect isn't all that great as anything but high speeds, and as mentioned above all the curves still apply, so as it brakes and slows things down, it will generate less back emf, and thus less "countertorque"(for lack of a better word), and thus not works as well. I implemented a system similar to this on an electric scooter as a secondary braking mechanissm and as sortof an experiment. It worked pretty well at high speeds but did little to nothing at low speeds.