View Single Post
Old 07-28-2018, 12:36 PM
altrez's Avatar
altrez altrez is offline
Silver Member
Join Date: Jun 2009
Posts: 556
Originally Posted by Matthew Jones View Post
There may be cases in which a PWM is beneficial, but in this case because you are trying to recover energy you are waisting by adding time to the over all wave form. And this is the worst most consumptive way to waist energy.

For instance you put 24 volt 1 amp into the PWM it breaks that up to a 50% duty cycle and passes it to the motor. The motor reaction to the impulses is to average out those pulses into a voltage. 24 volt 1 amp at 50% duty cycle is equal to 12 volt 1 amp. You have to average the on time with the off time.
Thats an automatic 50% loss of power just because of the averaging.

For recovery you are better off just lowering the voltage on the output which in turn lowers the input, as opposed to raising the voltage and segmenting it. Time is a power killer.

Thank you so much for explaining that to me! It makes perfect sense. The reason I used the PWM was to make sure I could get the same amperage going into the basic test motor as what I was reading going into the one battery test circuits motor.

And that seemed to work fine in this case.