SRM becomes competitive with IPMSM in performance

SRM = switched reluctance motor
IPMSM = interior permanent magnet synchronous motor
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The SRM technology developed this time is innovative.

IPMSM is currently used for called electrically or motor driven vehicles (EV, HEV, FCV) and others. It is a synchronous motor in which permanent magnets are buried in the rotor. It has many advantages. Its disadvantage is that the permanent magnet used contains rareearth(s).

It is said that China almost dominantly mines and export the rare earths at present, and has a plan to reduce the amount of the rare earths exported to 1/5 of the current one.
The motor-driven vehicles and the wind power generators will form a core business in near future market. The number of the motors used for them will increase depicting a steeply ascending curve. From this, it is clear that we must be faced with a vexed problem that the demand of the motors considerably increases, while the supply of the rare earths considerably decreases.

The SRM considerably improved is a synchronous motor not using the permanent magnet (rareearths). It has advantages of simple structure, excellent heat resistance and high rigidity, but it is inferior to the IPMSM in the torque and energy utilization efficiency. The disadvantages have prevented the SRM from being applied to the motor-driven vehicles. Where the SRM is designed to produce the performance comparable with that of the IPMSM, its size is too large to mount it on the vehicle.

The performance of the new SRM reached that of the IPMSM, and its some characteristics exceeded those of the SRM.

Co-developed by:
Prof. Akira Chiba et al (Tokyo University of Science) and Pro. Satoshi Ogasawara et al (Hokkaido University).

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