1. Field of the Invention
The present invention relates to a drive unit for a hybrid vehicle.
2. Description of the Related Art
Electrically driven vehicles conventionally have been provided with a drive unit including a drive motor, a generator-motor and an inverter unit. Further, in the inverter for the drive motor formed by a bridge circuit, direct current supplied from a battery is converted into three phase alternating current, and the alternating current is supplied to the drive motor. Further, by an inverter for the generator-motor, formed by a bridge circuit, three phase alternating current supplied from the generator-motor is converted into direct current and the direct current is supplied to the battery.
A pulse-width modulating signal is generated by the control unit and that signal is output to the respective bridge circuits to thereby switch transistors of the respective bridge circuits.
However, it has previously been necessary to provide for separate connection of an inverter to the drive motor and of an inverter to the generator-motor and, accordingly, the drive unit must be sufficiently sized to accommodate such connections.
Further, with a smoothing condenser, common to the respective bridge circuits, for stabilizing voltage generated when the transistors of the respective bridge circuits are switched ON and OFF, the lead wires connecting the respective transistors with the drive motor and the generator-motor are lengthy and the wiring is complicated.
Further, particularly in a drive unit in which a drive motor and a generator-motor are arranged on two different axes, there is no design integrating the inverter for the drive motor, the inverter for the generator-motor and the drive unit casing so that the drive unit is necessarily large-sized.