Abstract: The invention is a circuit (60) for controlling the operation of a variable reluctance machine having a plurality of phase windings. Pairs of phase windings (64, 66 or 65, 67) are controlled by a switching circuit having only three power switches which are controlled by a switch controller. Pairs of phase windings may be switched by one or more sets of switches each having the three power switches in several different modes of operation. The invention may be used to control multiple phase machines with an odd number of phases.

Abstract: An inverter (100) in accordance with the present invention for producing an AC output potential from a filter (40) containing an inductance (42) through which current flows to a load (12) in accordance with the invention includes first and second switches (Q1 and Q2) in series between a pair of DC reference potentials with each switch having a conductive and a non-conductive state controlled by control signals applied to control terminals of the switch; first and second freewheeling diodes (46) coupled in parallel respectively between first and second terminals of the first and second switches; a current sensor (38) producing a load current signal proportional to current flowing through the inductance to the load; and a controller (102), responsive to an error signal proportional to a difference between an output voltage produced by the inverter applied to the load and a signal proportional to a desired regulated output voltage of the inverter, a current reference signal varying at a frequency equal to the AC

Abstract: A power supply for converting a variable DC input potential (12) to a regulated DC output potential in accordance with the invention includes a plurality of DC to DC converters (300), each converter operating in response to a DC input potential having an operating range, having an input for receiving a DC input potential which is variable in magnitude, and an output for producing the DC output potential, the outputs of the converters being coupled together; a variable voltage divider (18) having an input coupled to the variable input potential, a plurality of connected stages (100) coupled to the input potential, at least one control signal applied to the variable voltage divider for controlling a number of stages across which the variable input potential is dropped; a switching circuit (200), coupled between the variable voltage divider and the plurality of DC to DC converters, responsive to at least one switching control signal, for coupling an output potential developed by at least one of the stages to at

Abstract: A circuit (40) for controlling a variable reluctance motor in accordance with the invention includes a first switch (Q1) having first and second electrodes, the first electrode being connectable to a first potential (14) of a DC power supply (12) and the second electrode being connected to a first terminal of each phase winding of the motor, and at least one additional switch (Q2-Q4), the first electrode of each additional switch being connected to a second terminal of an associated phase winding and the second electrode of each additional switch being connectable to a second potential (16) of the DC power supply; a number of freewheel diodes (20), a first electrode of each freewheel diode being connected to the second terminal of an associated phase winding and a second electrode of each freewheel diode being connectable to the first potential of the DC power supply; a first diode (24) coupled to the firt terminal of each phase winding; a controller (18) for generating control signals of each of the switches

Abstract: An inverter in accordance with the present invention includes a plurality of bipolar transistors (102) with each bipolar transistor having a freewheeling diode (108) poled in parallel with outputs of the bipolar transistor, a current transformer (112) in a positive feedback circuit (110) associated with each bipolar transistor causing a positive feedback to be applied from an output of the inverter to a base of each bipolar transistor to provide a base drive proportional to current flowing in a load coupled to the bipolar transistors, a rectifier (120), disposed in each of the positive feedback circuits for permitting current to flow to the base of the bipolar transistor when the bipolar transistor is conductive and blocking flow of current from the base to the emitter when the bipolar transistor is not forward biased.

Abstract: An H-bridge converter connected to a load includes a direct current power source, first and second pairs of switches alternately switched in order to connect the power source to the load, a plurality of snubber circuits correspondingly connected to the switches for protecting the switches from high currents and voltages, a sensing circuit connected between the first and second pairs of switches for sensing when each of the first and second pairs of switches are closed, and a snubber circuit counteracting circuit connected to a first snubber circuit of the first pair of switches, a second snubber circuit of the second pair of switches and to the sensing circuit for counteracting the flow of snubber currents in the sensing circuit from the first and second snubber circuits.

Abstract: A DC to DC series-parallel resonant converter (10) having a plurality of switches (Q1-Q4) which are switched alternatively between on and off states to cause electrical current to flow alternatively in first and second directions through a series-resonant circuit (60) Including a variable frequency ramp generator (28) having a reset input (R) for casuing an output ramp signal produced at an output to drop to zero in response to each reset signal; a comparator (30) having an input coupled to the output of the ramp signal generator, a second input for controlling the output DC voltage of the series-parallel resonant circuit and an output which changes level each time the ramp signal reaches the magnitude of the second input; a bistable circuit (32) having first and second outputs (Q, Q) for respectively outputting first and second signals, the output signals changing in response to a change in the output signal of the comparator coupled to the input; a pulse generator (26), coupled to the series-parallel resona

Abstract: A system for converting variable frequency multiple phase current into multiple phase current of constant frequency with a neutral having a multiple phase inverter with a neutral (N) is disclosed. A first input (34) is connected to the multiple phase inverter for receiving pulses of a positive polarity. A second input (36) is connected to the multiple phase inverter for receiving pulses of a negative polarity. A variable frequency multiple phase source (12, 14 and 16) of alternating current applies current to a multiple phase transformer (80, 142 and 180). Current from the transformer is applied to a full-wave rectifier (96) which has a first group of diodes (112) which applies the positive pulses to the input (34). A second group of diodes (116) applies the negative pulses to the input (36). The ripple frequency f.sub.

Abstract: A Darlington connected switching circuit (20) having a bipolar driver transistor (22) and at least one driven transistor (24) having a rapid and reliable turn-off characteristic with low losses suitable for use in power applications such as inverters. The collector to emitter potential of the at least one driven transistor is sensed by a comparator (26) to produce an output signal for controlling the conduction of minority carriers from the base of the driven transistor in response to sensing that the emitter to collector potential has become greater in magnitude than a reference potential (Vref) applied to the comparator. The reference potential is chosen to be at least a function of the switching characteristic of the driven transistor.

Abstract: A Darlington-type amplifier (10) having an input field effect transistor and an output bipolar transistor (T.sub.2) is disclosed with improved turn-off time. Turnoff is enhanced by short-circuiting the gate-to-source or drain capacitance of the input field effect transistor (T.sub.1) and after turnoff is complete of the input field effect transistor prior to turn off of the output bipolar transistor (T.sub.2) coupling the base of the output bipolar transistor to a reference potential to discharge minority carriers therein to complete turnoff.

Abstract: An inverter for producing a one or three phase output with neutral is disclosed. An LC resonant circuit is selectively switched by an inverter to produce one or three phases having a fundamental frequency equal to the frequency of each switching circuit within the phases of the inverter. The outputs are filtered to remove higher harmonics to pass the filtered output to the load. Energy is fed back into the resonant circuit by short circuiting the switching circuits at the time that the ouput voltage across a switching circuit is zero to minimize switching losses.

Abstract: A three phase inverter (40) is disclosed for use with loads (100) which are unbalanced. A transformer (80) having primary windings (82), (84) and (86) which are respectively connected to phase outputs (52, 54 and 56) has a secondary having individual windings (88, 90 and 92) connected in a delta configuration which minimizes the flow of unbalanced current in the unbalanced load. A second embodiment utilizes a transformer in an interconnected configuration. A neutral connecting the conductive switches to the load is unnecessary with the invention.

Abstract: An improved converter for converting a multiple phase variable frequency AC voltage having a high degree of noise produced by a variable frequency multiple phase voltage source into a DC voltage is disclosed. Triggering pulses for a full wave recification bridge are generated by a low pass filter which filters an output signal from the multiple phase variable frequency voltage source which introduces a constant phase shift independent of frequency. A rectangular wave form is produced having a frequency synchronized with zero crossing points of the output signal from the filter. A digital phase shift compensator phase shifts the rectangular wave form to produce a timing signal having a fixed phase shift throughout the variable frequency range which compensates for the phase shift introduced by the filter.

Abstract: An electronic circuit is provided for regulating a three-phase generator which includes: a circuit for sensing the average of the three-phase voltages; a circuit for sensing the highest phase voltage; and a circuit for sensing the highest phase current. The output of each of these circuits is compared to reference currents which represent an average voltage setting and high phase voltage and current limits, and an error signal is generated that is integrated over time. The integrated error signal is utilized as input to a comparator circuit which generates a pulsewidth modulated signal that represents deviation from the desired operating parameters. The pulsewidth modulated signal is applied to an output amplifier circuit which in turn serves to control the current through the generator's exciter field. An exciter field current detector is connected between the output amplifier and the input of a gain and compensation circuit in order to provide a negative current feedback circuit to minimize transients.