Sundstrand Corporation

Hamilton Sundstrand Corporation

Byron R Mehl

Timothy F Glennon

Donal E Baker

Alexander Krinickas, Jr

Pierre S Thollot

Raymond N Olson

An electrical starter-generator system includes a first starter-generator and a second starter-generator. A single drive controls both the first starter-generator and the second starter-generator such that their electrical current and power inputs are minimized and balanced.

Electric engine start with two motors and single motor drive

An improved motor controller for driving polyphase alternating current dynamoelectric machines from a direct current power source that employs two inverter bridges controlled with a state vector modulation symmetrical state sequence that has a desired 'chop' frequency so that each of their outputs produce a fundamental component that is exactly in phase but chop frequency components that are exactly 180 degrees out of phase with each other, with their outputs combined through respective interphase transformers to average the potentials of the chop frequency components.

Parallel inverter motor drive with improved waveform and reduced filter requirements

Prior voltage balancers for three-phase inverters are useful only with inverters which are not in wide use today. In order to overcome this problem, a voltage balancing circuit for a commonly used inverter balances N phase voltages produced on N output lines. The circuit includes switch controllers coupled to the N output lines for sensing the magnitude of each phase voltage and N-1 voltage combining circuits responsive to the switch controllers and coupled to N-1 output lines for modifying the voltage magnitudes on the N-1 output lines whereby the N phase voltages are maintained within a range of voltage magnitudes.

Voltage balancing circuit

An excitation system for a brushless generator having a main generator portion including a field winding disposed on a rotor and an armature winding disposed in a stator includes an exciter portion having a set of polyphase exciter field windings disposed in the stator and an armature winding disposed on the rotor and coupled to the main generator portion field winding. A first power converter is coupled to the main generator armature winding and a second power converter is coupled to the set of polyphase exciter field windings. Contactors are operable in a starting mode of operation to couple a source of electrical power to the first and second power converters and are operable in a generating mode to disconnect the source of electrical power from the first and second power converters. A control unit controls the power converters such that the power converters provide AC power to the main generator armature winding and to the set of polyphase exciter field windings during operation of the starting mode so that the rotor is accelerated. The control unit operates the power converters in the generating mode such that the second power converter provides AC power to the set of polyphase exciter field windings and the first power converter develops constant-frequency AC power.

Brushless generator having AC excitation in generating and starting modes

A power switch responsive to drive signals developed by a signal source includes driver and driven transistors connected in a Darlington configuration and a further transistor having a control electrode and first and second main current path electrodes wherein the first main current path electrode of the further transistor is coupled to first main current path electrodes of the driver and driven transistors, the second main current path electrode ofo the further transistor is coupled to a control electrode of one of the driver and driven transistors and the control electrode of the further transistor receives the drive signals. The power switch is maintained in a saturated state over a wide range of load current magnitudes.

High power switch

A regulated AC/DC converter includes a transformer having a primary winding which receives AC input power and a secondary winding, a rectifier coupled to the secondary winding for rectifying the output of same, a switching circuit coupled to the rectifier for developing trim voltage which is combined with the rectified output of the secondary winding to develop voltage-regulated DC output power and a switch control circuit for controlling the switching circuit whereby the switching circuit develops trim voltage which aids the rectified secondary winding output when such output is below a desired level and which opposes the rectified secondary winding output when such output is above the desired level.

Regulated AC/DC converter

A base drive circuit for a power transistor includes a plurality of discrete current sources. A condition of the power transistor circuit, which is a function of the transistor current, is sensed and controls the number of discrete current sources that are activated.

Incremental base drive circuit for a power transistor

A control circuit for a power converter which converts between polyphase periodic power and unidirectional power is disclosed. The control circuit includes first means for sensing a parameter of the periodic power and a ramp generator coupled to the first means for generating a ramp signal having a frequency equal to the frequency of the periodic power. A second means senses a parameter representative of a condition at the output of the power converter and a comparator combines the outputs from the ramp generator and the second means to generate a pulse train having a frequency equal to the frequency of the periodic power but shifted in time relative thereto, with the shift being dependent upon the output parameter. A phase-locked loop, of PLL, multiplies the frequency of the pulse train and additionally develops a signal which is coupled to the ramp generator to maintain the amplitude of the output therefrom at a constant level irrespective of changes in frequency of the periodic power. Multi-phase logic is coupled to the PLL and develops switching signals for switches in the converter.

Power converter control circuit

A power conversion system for converting between electric and motive power may be utilized either in a generating mode to generate electric power from motive power supplied by a prime mover or in a starting mode wherein motive power is developed by the power conversion system from electrical power and is supplied through a torque converter to the prime mover to start same. The power conversion system includes a main generator, an exciter and a permanent magnet generator, or PMG, which together comprise a brushless alternator. When operated in the starting mode, power is supplied to the PMG to cause it to act as a motor and thereby drive a rotor which is common to the PMG, exciter and main generator. Once a predetermined operating condition of the generator is attained, the main generator is supplied power from a motor control to cause the generator to act as a synchronous motor and the power supply to the PMG is disconnected. The torque converter is then commanded to transfer motive power from the generator to the prime mover to start same.

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Belvidere, IL, United States of America

Byron R Mehl