Starter/generator system with variable-frequency exciter control
AssigneeSundstrand Corporation
InventorsGregory I. Rozman, Albert L. Markunas, Paul E. Nuechterlein
Life of this patent
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Abstract
A control for a brushless generator is operable in a starting mode of operation to convert electrical power into motive power for starting a prime mover. The control applies AC power to an exciter field winding at a first frequency at the initiation of a start sequence and thereafter decreases the frequency of the power applied to the exciter field winding during the start sequence.
Claims21
A control for a brushless generator having a main generator portion including a field winding disposed on a rotor and which receives field current and an armature winding disposed in a stator wherein the rotor is movable with respect to the stator and a permanent magnet generator (PMG) having an armature winding coupled to a rectifier which is coupled to a voltage regulator wherein the generator is operable in a generating mode to convert motive power into electrical power and in a starting mode to convert electrical power provided to the main generator portion armature winding into motive power, comprising:
- an exciter having an exciter field winding disposed in the stator and an armature winding disposed on the rotor and coupled to the main generator portion filed winding;
- first and second power converters each having an input and an output;
- means operable in the starting mode for coupling a source of electrical power to the inputs of the first and second power converters, the output of the first power converter to the main generator portion armature winding and the output of the second power converter to the exciter field winding and operable in the generating mode for disconnecting the source of electrical power from the first and second power converters and connecting the voltage regulator to the exciter field winding and the input of one of the power converters to the main generator portion armature winding;
- and
- means coupled to the first and second power converters and operable in the starting mode for controlling the power converters such that the first and second power converters provide first and second AC waveforms at first and second frequencies to the main generator portion armature winding and to the exciter field winding, respectively, at the beginning of a star sequence and such that the second AC waveform changes to a third frequency less that the second frequency after the beginning of the start sequence and operable in the generating mode for controlling the power converter coupled to the main generator portion armature winding such that AC power is produced at the output of such power converter.
A control for a brushless generator having a main generator portion including a field winding disposed on a rotor and which receives field current and a set of armature windings disposed in a stator wherein the rotor is movable with respect to the stator and a permanent magnet generator (PMG) having a set of armature windings coupled to a rectifier which is coupled to a voltage regulator wherein the generator is operable in a generating mode to convert motive power into electrical power and in a starting mode to convert electrical power provided to the set of main generator portion armature windings into motive power, comprising:
- an exciter having an exciter filed winding disposed in the stator and a set of armature windings disposed on the rotor and coupled to the main generator portion field winding by a set of rotating rectifiers;
- first and second inverters and a rectifier bridge each having an input and an output;
- contactors operable in the starting mode for coupling a source of AC power to the input of the rectifier bridge, the output of the rectifier bridge to the input of the first and second power inverters, the output of the first inverter to the set of main generator portion armature windings and the output of the second inverter to the exciter field winding and operable in the generating mode for disconnecting the source of AC power from the first and second inverters and connecting the voltage regulator to the exciter field winding, the input of the rectifier bridge to the set of main generator portion armature windings and the input of one of the inverters to the output of the rectifier bridge;
- and
- means coupled to the first and second inverters and operable in the starting mode for controlling the inverters such that the first and second inverters provide first and second AC waveforms at first and second frequencies to the set of main generator portion armature windings and to the exciter field winding, respectively, at the beginning of a start sequence and such that the frequency of the second AC waveform continuously decreases during the start sequence until a particular rotor speed is reached after the beginning of the start sequence and operable in the generating mode for controlling the inverter coupled to the main generator portion armature winding such that AC power is produced at the output of such inverter.
Dependencies are inferred from the claim text.