OVERVOLTAGE PROTECTION FOR A MOTOR VEHICLE ELECTRICAL SYSTEM IN THE EVENT OF LOAD SHEDDING

摘要

A method for operating a motor vehicle electrical system which includes an electric machine, and an active bridge rectifier connected to the electric machine via phase connections. After the bridge rectifier has been operated at least once in a short circuit operating mode, a determination is made, based on at least one feature of a signal which characterizes a voltage that drops between the direct voltage terminals of the bridge rectifier, whether the signal has exceeded the upper threshold value due to a cable break at at least one of the direct voltage terminals. If so, the bridge rectifier is subsequently operated in the short circuit operating mode for an extended period of time, and/or a control signal having a second switching time greater than that in the first method phase is used for controlling the active switching elements.