Patent ID: 7187088

Claim:
A power supply apparatus for an electric vehicle which includes a vehicle power supply for driving an electric motor and other vehicle equipment comprising: intermediate voltage application means for setting a line defined by an intermediate voltage between a drive voltage and a ground voltage of said vehicle power supply as a ground line for said other vehicle equipment, and power supply means for producing a voltage to be applied to said other vehicle equipment based on the drive voltage of said vehicle power supply and the intermediate voltages, wherein said power supply means includes a power supply circuit operatively connected to an oscillator, a photo-coupler including a photo-diode and a photo-transistor, FETs Q 1 and Q 2 , diodes, a capacitor and resistors for producing the voltage to be applied to the other vehicle equipment, and wherein when a voltage is supplied from a controller to the power supply circuit, the oscillator is rendered operative with a voltage from the power supply circuit, the oscillator outputs a pulse waveform turning on and off the FET Q 1 , and when the FET Q 1 is turned on, the capacitor is charged, and when the FET Q 1 is turned off, the photo-diode emits light and the photo-transistor is turned on such that a voltage from the capacitor is applied to the FET Q 2 thereby turning on the FET Q 2 .