Electromagnetic Motor

Here's a speculative - even fanciful response - off the top. To provide a variable speed control, a multi phase drive to the stators' coils provides a torque, which with increasing frequency, spins the wheel faster. But a constant torque at increasing speed takes increasing power. So at max drive power, the current into the coils should drop as the frequency increases. At some point, a low current high frequency drive gets increasing losses (I speculate) so pulling the stators to decrease the iron cross section in the circuit (possibly) keeps losses down....

Brian W