Abstract: A power conversion system allows for redundant starting and generating functions together with fault tolerant operation through the multiple use of power conversion equipment.

Abstract: A control system for controlling an inverter having a connector for connecting the output of the inverter to a load wherein a temperature sensing arrangement senses the temperature of the connector and a controller responds to the temperature of the connector for controlling the inverter in order to control the inverter output.

Abstract: 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.

Abstract: In a system for starting an aircraft turbine from a low voltage direct current power supply, the low voltage power supply is coupled by an invertor to the turbine's a.c. generator. The generator operates as a motor during starting. The invertor is initially coupled directly to the generator during starting, and to the generator via a step-up transformer after the speed of the generator increases. In a preferred embodiment of the invention, the transformer is an autotransformer used to step down the output of the generator when operating as a generator after the turbine has been started.

Abstract: Prior VSCF inverters have utilized relatively expensive bipolar transistors and associated base drive circuits together with an input autotransformer which unduly add to the cost and weight of the system. In order ot overcome these problems, a VSCF power converter includes an inverter which utilizes less expensive power switches such as insulated gate bipolar transistors, MOS controlled thyristors or power FET's, together with an output autotransformer coupled between the inverter output and a filter input which eliminates the need for the input autotransformer. The present system is less expensive and lighter than prior VSCF power converters.

Abstract: An electrically compensated constant speed drive includes a mechanical differential having first and second input shafts and an output shaft wherein a prime mover is coupled to the first input shaft, a brushless generator is coupled to the differential output shaft and includes a control permanent magnet generator (PMG) and a main generator which develops output power and a speed compensation link is coupled between the control PMG and the second differential shaft. The speed compensation link includes a dynamoelectric machine coupled to the second differential input shaft and a power converter which interconnects armature windings of the control PMG and electrical power windings of the dynamoelectric machine.

Abstract: Prior starting/generating systems which operate a generator as a motor to start a prime mover have been inefficient since motive power was delivered to the prime mover through hydrostatic trim and differential components of a constant speed drive interposed between the prime mover and the generator. In order to overcome this problem, means are provided between the prime mover and the generator for bypassing these components of the constant speed drive when operating in a starting mode so that motive power is transferred directly to the prime mover. This, coupled with the fact that the generator is operated as a motor responsive to generator speed and/or generator power factor, increases the efficiency of the system when in the starting mode.

Abstract: 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.

Abstract: Prior types of power conversion circuits for converting AC power into DC power have generated large amounts of undesirable electromagnetic interference (EMI) due to the rectification of the AC power. Such EMI has been reduced in the past by large and heavy filters which have undesirably increased the size and weight of such conversion circuits. In order to overcome this problem, a harmonic reduction circuit according to the present invention includes a current sensor for sensing the current in the AC lines, circuitry for developing a pulse width modulated (PWM) waveform having a duty cycle dependent upon the sensed AC line current and a switching circuit coupled to the AC power line and controlled by the PWM waveform developing circuitry for compensating the AC line current whereby undesired harmonics therein are reduced.

Abstract: Prior types of generating systems for producing AC and DC output power have utilized integrated drive generators for producing the AC power and means for rectifying the AC power developed by the drive generator to produce the DC power. However, such types of systems encounter various disadvantages, including less than desirable reliability of the DC power, distortion in the AC power caused by rectification thereof to produce the DC power and reduced efficiency. In order to overcome these problems, a hybrid generating system according to the present invention comprises an AC power generating section driven by a prime mover for generating AC output power and a DC power generating section independent of the AC power generating section, also driven by the prime mover for generating the DC output power wherein each of the AC and DC power generating sections includes a permanent magnet generator.

Abstract: A permanent magnet generating system includes first and second permanent magnet generators, or PMG's each having a permanent magnet rotor structure and a stator structure. Each stator structure has at least one stator winding disposed therein and the stator windings of the PMG's are connected in series so that the voltages developed thereby add vectorially to develop a combined output voltage. The position of the stator windings of one PMG is adjustable relative to the position of the stator windings of the other PMG to vary the phase angle between the two output voltages of the PMG's so that the combined output voltage can be controlled at a desired value irrespective of changes in operating speed or load.

Abstract: A generating system including a permanent magnet generator having a stator, a rotor journalled for rotation in proximity to the stator and normally separated therefrom by a small air gap. Permanent magnets and windings are provided on the stator and the rotor respectively, or the reverse as desired and a detector is provided for sensing the development of an electrical fault in the winding and for moving the stator away from the rotor to increase the air gap thereby reducing the magneto motive force available to induce current in the winding to prevent burn out of the winding.

Abstract: An apparatus for improving the transient response of a power supply system having an alternator for developing AC power and a rectifier for converting the alternator output into primary DC power includes a second rectifier for rectifying the alternating current power from the alternator to derive supplemental DC power and means responsive to a parameter of the primary DC power for coupling the supplemental DC power to the primary DC power when the parameter drops to a particular value so as to minimize the effect of load changes on the system. The purpose of the disclosed system is to allow the alternator to be sized for minimum electromagnetic weight while at the same time providing a simple means of reducing load application transients.

Abstract: This invention relates to a motor control circuit for a permanent magnet motor having a rotor and motor windings. A motor winding transformer circuit is coupled to motor windings and provides an output signal representative of the magnitude and direction of the real current present in the motor windings. A rotor speed/position sensing circuit provides an output signal representative of the motor speed and direction.

Abstract: An improved end turn construction to improve cooling in a dynamoelectric machine and to axially reduce the size thereof. The machine includes a body (12) of magnetizable material having opposed ends (18) an opening (14) extending between the ends and the plurality of slots (50) about the opening (14). A rotor (16) is disposed within the opening (14) and journalled for rotation therein and electric conductors (52) are located in the slots (50) and extend to ends (54, 56) just past the ends (18) of the body (12). End turns (58, 60, 68) each interconnect a predetermined pair of the conductors (52) and extend substantially circumferntially and radially of the rotor axis with no appreciable extension axially of the axis.

Abstract: A microcomputer implemented apparatus and method for detecting the occurrence of a shorted diode in the rotating rectifier of a brushless alternator. The alternator current, voltage and power output and the alternator temperature are measured. The anticipated exciter field current is determined for the alternator output and operating conditions and compared with the actual exciter field current. An actual exciter field current in excess of the anticipated current indicates a rectifier fault.

Abstract: A neutrally clamped pulse width modulated inverter. The inverter includes a bidirectional switch which, when turned on, clamps the voltage applied to the inverter output filter to neutral or ground to provide a pulse width modulated waveform having a voltage swing of one-half of the rail-to-rail voltage of the inverter over each half cycle of the output. The bidirectional switch also provides a path to ground for any regenerative current flowing from the load so as to enable the regenerative current capacity of the inverter power supply to be reduced.

Abstract: A method and apparatus for controlling switches in an n-phase static inverter of the bridge type is disclosed wherein the inverter includes n pairs of switches connected across two DC voltages, with a phase output being developed at the junction between switches of each pair. In such an inverter, at any particular time, n.sub.1 phase outputs are connected to one of the DC voltages while n.sub.2 phase outputs are connected to the other DC voltage, where n.sub.1 .ltoreq.n.sub.2 and n.sub.1 +n.sub.2 =n. The n.sub.1 phase outputs are identified by logic circuitry and the switches associated with such phase outputs are operated during times when a pulse width modulation waveform is in a low state so that all phase outputs are connected to the same DC voltage. The method and apparatus of the present invention reduces the number of switching occurrences to the minimum required to achieve defined applied voltage pulse width modulation.

Abstract: A power switching circuit for controlling the power from a DC supply to a regenerative load. The switching circuit includes a plurality of parallel connected MOSFETs. A first diode is connected in parallel with the MOSFET switches and poled to conduct reverse current from the load. A second diode is connected in series with the MOSFETs to block the flow of reverse current through the MOSFETs.

Abstract: An inverter control system for selecting an angle set defining an inverter output waveform in response to various operating conditions of the inverter. The inverter control system selects an angle set in response to signals representing the power factor of the load and the normalized DC bus voltage to minimize the harmonic content of the inverter output waveform and to compensate for voltage drops occurring between the DC power supply and the load. The inverter control system is also responsive to the inverter filter output current to detect fault conditions and in response thereto, to select at least one angle set defining a waveform to reduce the voltage at the load to zero while allowing the filter output current to increase to a given percentage of the rated current.