Method and system for controlling a permanent magnet machine driven by an inverter is provided. The method allows for monitoring a signal indicative of a fault condition. The method further allows for generating during the fault condition a respective signal configured to maintain a field weakening current even though electrical power from an energy source is absent during said fault condition. The level of the maintained field-weakening current enables the machine to operate in a safe mode so that the inverter is protected from excess voltage.
This invention was made with U.S. Government support through Definitized Subcontract C-HEV-5A under MRI/CHRYSLER LETTER SUBCONTRACT NO. ZAN-6-16334-01, which subcontract was in turn issued under MRI/CHRYSLER PRIME CONTRACT NO. DE-AC36-83CH10093" awarded by the Department of Energy, and, in accordance with the terms set forth in said contracts, the U.S. Government may have certain rights in the invention.