Patent ID: 8120200

Claim:
A control methodology for a hybrid vehicle electrical system including one or more electrical loads, an engine-driven AC electric machine operable as a generator for supplying power to said electrical loads via a high voltage bus, and a high voltage battery pack coupled to the high voltage bus by a relay that can be opened to disconnect the battery pack from the high voltage bus under fault conditions, the control methodology comprising the steps of: detecting a fault condition requiring disconnection of the battery pack from the high voltage bus; and in response to detection of the fault condition: determining if a current of said battery pack is above a threshold; if the current of said battery pack is above the threshold current, controlling said electric machine based on vector current commands calculated to output a voltage effective to drive the current of said battery pack toward zero current; activating said relay to disconnect said battery pack from the high voltage bus when the current of said battery pack falls below said threshold current; and after disconnection of said battery pack from said high voltage bus, controlling said electric machine based on vector current commands calculated to maintain an operating voltage of said high voltage bus at a target voltage to enable continued operation of said electrical loads.