Automotive Power Generation Control System for Higher Fuel Economy

Keiichi Mashino, Automotive Products Division, Hitachi, Ltd.
Yasuo Nagai, Semiconductor & Integrated Circuits Division, Hitachi, Ltd.
Katsuji Marumoto, Hitachi Research Laboratory, Hitachi, Ltd.


For reasons of comfort and safety, automobiles are being equipped with more and more electronic devices.

The additional electrical load incurred by these devices requires a greater driving torque for the increased generator output. This, in turn, affects fuel consumption.

Furthermore, the trend towards lower idle speeds to increase fuel economy creates the possibility of engine stall due to the transient torque caused by rush currents through the large electrical loads.

It is, therefore, necessary to have systems that can first detect the driving status as well as the status of electrical loads and the battery, and then can control generator output as necessary.

Hitachi, Ltd. has established an intelligent electrical power generating system featuring a highly integrated Power LSI. With this system, the practical fuel consumption is improved by at least 0.5% compared with conventional generators.

In order to help reducing customer development turn-around time, a simulation program for estimating fuel consumption and electrical charge balance from just vehicle driving condition input has been developed.

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