Patent ID: 7365521

Claim:
A method of operating an engine with permanent magnet generator (PMG) and power conversion unit (PCU) including the steps of: (1) initiating a start sequence; (2) monitoring PMG rotational speed to assist in proper execution of an engine start; (3) generating an AC excitation by use of a PCU, wherein the AC excitation is used to operate the PMG as a motor and cause an engine to rotate; (4) controlling speed of the PMG by controlling the AC excitation generated in the PCU during an engine start including at least one of: (a) using sensorless control method; (b) using at least one of an open or a closed loop control method; and (c) using a control method that enables motoring start; (5) controlling torque produced by the PMG during an engine start by controlling the AC excitation applied by the PCU including at least one of: (a) using a torque versus speed characteristic; and (b) using a soft start characteristic; (6) cutting of starter assist automatically at a predetermined PMG speed, monitoring for fault conditions prior to, during, and after the engine start to ensure that a proper action is taken including at least one of: (a) verifying that the engine is rotating in the correct direction; (b) verifying correct phasing of the PMG voltage; (c) verifying proper PCU operation prior to, during and after the engine start sequence; and (d) detecting a ground fault within at least one of the PMG, PCU and a feeder cable; (7) controlling the start sequence by executing a control logic algorithm including at least one of: (a) executing an engine brake function prior to executing engine start to ensure that the engine does not rotate in an incorrect direction; (b) executing an engine brake function prior to executing engine start to halt an engine that is rotating in an incorrect direction prior to engine start; (c) executing an engine brake function prior to executing engine start to ensure proper alignment of PMG rotor magnets and that the AC excitation from the PCU is achieved; and (d) incorporating control logic to alter the control logic algorithm in a predetermined manner dependent upon the state of a signal.