Protection circuit for a drive circuit of a permanent magnet motor and corresponding system

摘要

It is presented a protection circuit (1) for a drive circuit of a permanent magnet motor (50) being powered by a main DC source. The protection circuit comprises a protection circuit DC source (30,31); a changeover switch (10) being arranged to select an input to a gate of a main drive switch of the drive circuit, the input being selectable between an output of the protection circuit DC source (12) and a second control signal; and a changeover control device (11) connected to control the changeover switch (10), which changeover control device (11) is arranged to ensure that the changeover switch (10) is connected to the output of the second side of the protection circuit DC source (12) when an overvoltage is detected.