for example with a 50v battery, 60a motor current, 30a battery current at 50% duty cycle, it means 60a @ 50v is being taken from the battery half the time, which averages to 30a @ 50v, while the motor sees 60a @ 25v the whole time, assuming constant speed from the load. the motor is shorted to itself during the times the battery is not supplying current, and due to the motor’s inductance and short time scales of the switching cycles, the current in the motor changes very little during the on-off current cycles the battery sees. very small changes in duty cycle result in very large changes in motor current.
https://en.m.wikipedia.org/wiki/File:PWM_duty_cycle_with_label.gif
