Abstract: A switching circuit (10) in accordance with the invention includes a snubbing circuit (12) which couples energy stored in energy storing elements (24), (28) and (36) to the switching circuit. A capacitive storage (20), coupled to a DC potential (16), supplies electrical current which flows to an electrical load (18) through at least one switch (14) which is coupled to the snubbing circuit.

Abstract: A drive ciruit for a load switch (104) controlling current flow through an electrical load (106) in accordance with the present invention includes a switching signal source (10), a first optical coupler (110), coupled to the switching signal source which turns on to produce an output drive signal in response to a first level of a switching signal (100) from the switching signal source to control turning on of the load switch; and a second optical coupler (114) coupled to the switching signal source which turns on to produce an output drive signal in response to a second level of a switching signal from the switching signal source to control turning off of the load switch.

Abstract: The drive circuit for controlling conductivity of a load switch (12) for controlling current flow through an electrical load (14) in accordance with the invention includes a DC source (20) having a positive terminal and a negative terminal; first and second voltage limiting devices (100) and (102) coupled together at a junction point (108) and an electrode of the first voltage limiting device being coupled to the positive terminal and an electrode of the second voltage limiting device being coupled to the negative terminal and a control circuit (24 and 28) causing current flow through only one of the voltage limiting devices with a reverse current breakdown which reverse biases the control electrode of the load switch causing the load switch to turn off.

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: 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: A filter system for removing selected frequencies from AC power provided on at least two phase lines and a neutral line includes a phase-to-phase filter for removing a first selected AC component at a first frequency from the AC power wherein the frequency component has a line-to-phase displacement within first or second ranges. A phase-to-neutral filter is also provided for removing a second selected AC component at a second frequency different from the first frequency from the AC power wherein the second frequency component has a line-to-line phase displacement outside of the first and second ranges.

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: In a single phase AC motor having a main winding (1) and an auxiliary winding (2) both connectable to an AC power source (4), and having a start switch (24, 49) for automatically connecting and disconnecting the auxiliary winding to and from the AC source (4) in starting and running modes, respectively, and having a user operated reversing switch (7-12) for reversing the voltage polarity applied from the AC source (4) to one of the windings relative to the other winding, circuitry is provided for detecting the polarity reversal by sensing when one of the main and auxiliary winding voltages shifts from a leading to a lagging position relative to the other winding voltage, whereupon the circuit automatically instantly reconnects the auxiliary winding (2) to the AC source (4) to immediately apply reverse torque.