Improving Motor Efficiency
"Alternatively, it is possible to simulate a multi-speed transmission electronically by breaking up the phase winding pairs into multiple sets that can be rewired on the fly by the inverter to change either the apparent number of poles or the number of phases. Each of these solutions effectively changes the rotational angle that the magnetic field produced by the stator has to act upon—acting over a shorter arc trades a higher torque for a lower synchronous speed and vice versa—but a caveat is that this would require very different inverter hardware and software, so don’t expect to see these solutions implemented in an OEM EV anytime soon. That said, history shows that whenever a mechanical solution can be replaced by an electronic one, it is all but sure to be adopted…eventually."