POWER SUPPLY FOR MOTOR VEHICLE

摘要

PURPOSE:To provide a power supply for motor vehicle in which a main switch of low withstand voltage can be used and current leak from a floating power supply for running through the main switch is blocked even the insulation between the main switch and the car body earth is deteriorated. CONSTITUTION:A power supply 3 for a running motor comprising a plurality of batteries 3a-3f connected in series is floated from the car body earth. A step-down DC-DC converter 4 having isolated input and output receives the starting power or signal from a part 3a of the power supply 3a at least through a diode 7 and a main switch 2 thus starting the DC-DC converter. The DC-DC converter is fed with power from the power supply 3 for running motor and provides a power supply VB being stepped down for auxiliary machine on the output side.