Abstract: An AC variable speed driving apparatus including an AC motor and an inverter for driving the motor. The AC motor includes a synchronous motor and an induction motor. The synchronous motor includes first stator windings and a first rotor having a permanent magnet. The induction motor includes second stator windings and a second rotor. The first and second stator windings are disposed so that they do not magnetically interfere with each other. The first and second rotors are mounted on a common axis of rotation. The inverter supplies AC power to the stator windings so that the synchronous motor and the induction motor are driven independently. A highly efficient, large output and low cost system can be realized in a wide speed range.

Abstract: An electric system for an electric vehicle includes a main battery used for driving the vehicle, an auxiliary battery used for accessories of the vehicle, an AC motor for driving one or more wheels, an inverter for converting DC power supplied from the main battery to AC power to be supplied to the AC motor, and an auxiliary battery charging circuit for charging the auxiliary battery by using the AC power from the inverter. When charging the auxiliary battery, the AC power is insulatedly transformed and then rectified. In another example, an input capacitor in the inverter is charged by a DC-DC converter connected with the auxiliary battery as its power supply when the inverter starts. The system enables the auxiliary battery charging circuit to be small, light and low cost. The system can also charge the auxiliary battery for accessories even when the vehicle is stopping.