Common-mode current sensing system and protection method for power converters

Abstract

A common-mode current sensor system and method for a traction inverter of an electric hybrid vehicle. The system and method detects/reduces excess common-mode currents that can be caused by the presence of alternating current (AC)-chassis type short circuit faults at the outputs of an inverter used for driving a two or more-phased load. In an embodiment, the system detects the presence of an AC-chassis fault of any varying strength, e.g., weak, medium, hard, in respective parallel paths. The system and method can isolate a particular AC-chassis type fault to a particular phase leg of the inverter thereby obviating a need of having to shut-down and/or re-program each phase leg of the whole power supply and vehicle operation. Rather, upon detecting a chassis short, a fault signal is asserted to control shutting down of one or more inverter switches without having to shut-down the vehicle or negatively impact the vehicle status.