Hybrid/electrical vehicle HV AC system leakage and ground fault detection

摘要

Apparatus and methods for detection of a ground fault on a DC side as well as on an AC side of an inverter are presented. A detection means can receive forward and reverse current and provide an induced current based on the difference between them. A parameter associated with the induced current, or a parameter associated with a voltage generated by conduction of the induced current through a device, can be used to detect a ground fault. In addition, a detection means can be configured to receive transient current, and a resulting voltage at the detection means can be used for fault detection. A detection means can be disposed at the DC side of an inverter or at the AC side of the inverter. Apparatus and methods can be configured to detect AC leakage current caused by a ground fault.

主权项

1. A ground fault detection circuit, comprising:
a high voltage (HV) energy storage device (ESD), that is coupled to and provides a DC voltage to a high voltage DC link comprising a positive dc bus and a negative DC bus; an inverter, coupled to said ESD by said DC link, that provides alternating current output to an electric motor; a detection means disposed between said inverter and said electric motor, through which a first conductor conducting a first phase current between a first node at a first phase leg of said inverter and a first winding of said motor passes, a second conductor conducting a second phase current between a second node at a second phase leg of said inverter and a second winding of said motor passes, and a third conductor conducting a third phase current flowing between a third node at a third phase leg of said inverter and a third winding of said motor passes, said detection means receiving first direction current and opposing direction current flowing between said inverter and said electric machine; and providing an induced current; a fault determination module (FDM) that receives said induced current and detects said ground fault from said induced current.