초록 ▼

A conventional motor controlling circuit is adapted to control an inverter that drives a permanent magnet generator as a motor to spin an engine to a speed sufficient to permit the engine to start. The commutation frequency is adjusted as a function of speed utilizing an automatic commutation freque

A conventional motor controlling circuit is adapted to control an inverter that drives a permanent magnet generator as a motor to spin an engine to a speed sufficient to permit the engine to start. The commutation frequency is adjusted as a function of speed utilizing an automatic commutation frequency adjustment circuit. This circuit has multiple commutation frequency ranges that overcome a large initial bearing drag during low speed operation while still permitting high speed operation. The automatic commutation frequency adjustment circuit preferably generates first and second voltage ramps that overcome the initial bearing drag and accelerate the generator at a rate fast enough for sufficient back EMF to be generated for a closed-loop commutation phase. A speedup circuit operates during the closed-loop commutation phase to achieve the high speeds typically necessary for engine starting. The inventive circuits even permit a turbine type engine to be successfully started.

대표청구항 ▼

[ What is claimed is:] [1.] A line power unit which delivers electrical power to a grid from a three phase permanent magnet generator, comprising:a full wave rectifier connected to the three phase permanent magnet generator, said full wave rectifier converting a three phase AC voltage from the three

[ What is claimed is:] [1.] A line power unit which delivers electrical power to a grid from a three phase permanent magnet generator, comprising:a full wave rectifier connected to the three phase permanent magnet generator, said full wave rectifier converting a three phase AC voltage from the three phase permanent magnet generator to a DC voltage;a DC bus connected to the output of said full wave rectifier;a main inverter connected to said DC bus, said inverter functioning as a current source and transforming the DC voltage to a controlled three phase alternating voltage;an inductor unit connected to the output of said inverter;a contactor unit selectively connecting and disconnecting said inductor unit to and from the grid;a transformer connected between said inductor unit and said contactor unit;an engine for driving said three phase permanent magnet generator;an engine start inverter unit connected to said DC bus and the three phase permanent magnet generator,wherein upon a start phase said contactor unit closes to connect the grid to said transformer to develop three phase AC power and thereby spin the permanent magnet generator as a motor to allow the engine to be started,said engine start inverter unit including:a three phase start inverter connected to said DC bus and the three phase permanent magnet generator,a gate drive/inverter interface controlling the three phase AC voltage supplied to the three phase permanent magnet generator by said start inverter,a brushless motor control circuit connected to said gate drive/inverter interface, and an input receiving a signal measuring an amount of current being drawn by the motor, and a back EMF input receiving a back EMF from the three phase permanent magnet generator being driven as a motor,said brushless motor control circuit controlling said gate drive and inverter interface according to a speed command thereby causing said three phase start inverter to deliver a three phase voltage to the permanent magnet generator at a controlled commutation frequency, andan automatic commutation frequency adjustment circuit connected to said brushless motor control circuit for automatically adjusting the commutation frequency as a function of permanent magnet generator speed.