I've been looking at used industrial motors that could work to power an electric car and it seems like 90% of the motors used in industry are induction type, why is this? My guess is simplicity, but aren't other types of motors more efficient or have better torque curves? I would think permanent magnet motors would be more efficient. I had heard that synchronus motors produce instant torque from a stall. Also there's the issue that the power factor gets all screwed up on an induction machine so the real power is less than apparent power right? Finally are induction motors the only motors that use frequency to vary rpm?

 

they are used because they are economical. Synchronous has a max torque rating. It will loose torque instantaneously once it 'pulls out'. Characteristics of the load spec the motor, as does characteristics of the supply. The motor only converts the energy, at yes, some loss. PF is of concern when designing the source. Current availability and the systems ability to handle it will get you going strong. Permanent magnet motors are likely the wave of the future, as they become more available. Liquid cooling provides a denser package.