Power supply system for a motor vehicle having a low-voltage onboard power supply and having a higher-voltage onboard power supply

摘要

A power supply system for a motor vehicle has a low-voltage onboard power supply and a higher-voltage onboard power supply. Either the minus connection or the plus connection of at least the high-power consuming devices of the higher-voltage onboard power supply is coupled via a central bus line with the corresponding (minus or plus) connection of the low-voltage onboard power supply. The central bus line is provided with a controllable switch. Devices are provided for measuring the voltage of the low-voltage onboard power supply, and/or for measuring the differential current between the current flowing on the plus line and the current flowing on the minus line in the higher-voltage onboard power supply. The controllable switch is opened when the voltage in the low-voltage onboard power supply has exceeded a defined voltage threshold and/or when the differential current has exceeded a defined current threshold.