With the challenge to match peak electric motor efficiency to the vehicle drive cycle, IMRA are developing world-class electric motors using the variable flux, ‘memory’, principle.
Conventional permanent magnet motors have a peak efficiency area which is not well matched with the area most used by passenger vehicles, i.e. urban driving. In memory motors the magnetic field can be at a maximum when high power is required, e.g. for highway driving and maximum acceleration, but easily reduced when lower power is required, e.g. for urban driving. A reduced magnetic field inside the motor also reduces the losses, giving improved efficiency in the area where passenger vehicles are used most.
Memory motors are a particularly challenging technology but by collaborating with academic institutes and software companies, and with several years experience, we have developed the analysis required and validated this with full size traction motor prototypes.