Is there a 'rule of thumb' for figuring out much torque it takes to put out xx volts and yy amps from a PMA given the gauss of the magnet and the N turns of the coils? Should spin free open circuit, and really stall out short circuit, and be somewhere in the middle during operation. I guess the 'max power' point is when the load drags the volts down to half the open circuit value? I guess the current here would be half the short circuit current too? I want to rig the pwm controller to not load down the pma too much under low power/low torque/ slow spinning conditions, like from a stirling or micro hydro. In general volts (and current) is proportional to rpm... someone got some formulas that are a little more specific?
- posted
18 years ago