And why does Toyota use a brushless DC motor (BLDC) in the Prius?
Converting electrical energy to mechanical energy to achieve a specific result – rotational speed, position or torque — is not simple. Besides the motor itself, the there are three crucial components that comprise the motor drive: the power converter, the controller and the sensor.
Using complex algorithms based on load demands, an inverter stage within the power converter converts DC from a car battery to three-phase AC, required by both induction and BLDC motors; low power isolated gate drivers convert the pulse-width modulation (PWM) signals from the controller into gate pulses that control power handling switches, either insulated gate bipolar transistors (IGBTs) or MOSFETs.
Clearly, settling on a motor and controller are non-trivial exercises.
As far as Tesla’s choice? It’s about the algorithms. The company admits that induction machines are more difficult to control, but unlike DC brushless, where magnetic losses increase with size, induction machines don’t pay such a penalty.
For more on active Miller clamping, soft turn-offs and “tail” currents, please read Power Electronics in Motor Drives. You might be able to build your own electric vehicle.