Bidirectional DC-to-DC converter for motor control unit of electric vehicle

A recent EV trend is to increase the operating voltage of a propulsion motor to improve the efficiency and performance. To feed a high voltage to motor control unit, it generally employs a front-end bidirectional converter. Because the boosting operation of the converter produces a high output voltage, the converter needs an output capacitor, which has a high working voltage resulted in cost increasing. To solve the problem, we present a modified bidirectional converter, which can decreases the working voltage of the output capacitor. Basic characteristic of the proposed converter is similar to the conventional boost converter. The difference comes from the structure of the output terminal. The output capacitor is connected to the input battery in series. Owing to this circuit configuration, the working voltage of the output capacitor becomes lower than that of the conventional boost converter. After theoretical analysis, we carry out simulations and experiments to verify the validity and the performance comparing with the conventional converter.