AC Drive System for Electric Vehicles

Shotaro Naito, Automotive Products Division, Hitachi, Ltd.
Nobuyoshi Muto, D. Eng., Hitachi Research Laboratory, Hitachi, Ltd.
Takeo Takagi, D. Eng., Mechanical Engineering Research Laboratory, Hitachi, Ltd.
Yoshinobu Kochi, Industrial Components & Equipment Division, Hitachi, Ltd.


Recent concerns about air pollution have underlined the possibility of a potential market for electric vehicles (EVs).

In California, regulations mandating the sale of zero-emission vehicles (ZEVs) by 1998 have been implemented. It is expected that EVs will be the only vehicles that can comply with the ZEV regulations.

In support of EV technologies, Hitachi, Ltd. has developed a new compact, lightweight, and high-efficiency AC drive system consisting of an induction motor and an insulated gate bipolar transistor (IGBT) inverter.

In comparison with industrial use motors, the weight and size of the new induction motor has been reduced by adopting an aluminum frame.

The weight and size of the inverter has also been reduced by adopting a high speed, low loss IGBT, as well as a water cooling heat sink with low thermal resistance. The control system features a multiple function microcomputer equipped with a new vector control algorithm that guarantees maximum efficiency performance in response to changing load conditions.

The above developments have resulted in a practical AC drive system for electric vehicles.

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