Importance

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Abstract

A motor generator system in accordance with the invention includes a prime mover (21) for driving an output shaft (18); a main motor generator (16, 105), having a rotor driven by the output shaft, for producing electrical power on a plurality of stator phase windings (36a-36c) in response to the prime mover rotating the output shaft and for driving the output shaft in response to operation as a motor, an exciter (14, 102), having a rotor driven by the output shaft, for applying excitation to a field winding (34) of the main motor generator during operation for producing electrical power on the plurality of phase windings and for applying current to the field winding of the main motor generator to produce a magnetic field in the field winding during operation of the main motor generator as a motor, a time varying signal source (200) for applying a time varying signal having a fundamental frequency 202 to a field winding (28) of the exciter, a main inverter (114), responsive to signal (302) representing a rotary position of the rotor of the main motor generator, for commutating application of current to the at least one of the plurality of phase windings to control operation of the main motor generator during operation as a motor while simultaneously maintaining one of the plurality of phase windings in a non-commutated stated in which no current is cause to flow therein by the main inverter, circuitry (300), coupled to the stator phase winding maintained in the non-commutated state, for detecting an amplitude modulation of voltage across the non-commutated phase winding at twice the fundamental frequency representing the rotary position of the rotor of the main motor generator and producing the rotor position signal in response to the detected amplitude modulation to control commutation of current in at least one of the plurality of stator phase windings.

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First Claim