Quote:
Originally Posted by jpirkola
What I was hoping for was to be able to set the controller to limit itself to use a maximum voltage lower then the pack actual voltage. E.g. the controller can stand a 144 nominal volt battery pack. The controller is set to only pass 120 volts maximum to the motor.
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That's not quite the way the controller works.
It applies the full pack voltage to the motor windings, and varies the pulse width so the motor 'sees' a lower average voltage.
Really the controller has a target current, and changes the pulse width to get closer to the goal. So even if the pack voltage sags, the controller just increases its pulse width to compensate. The driver may not even notice the minor response lag.
Direct PWM does mean the motor windings have to withstand the full pack voltage. That's not usually a problem unless you are running absurdly high traction voltage.