Abstract: A bidirectional solid state power switch module includes two solid state switches, each having an antiparallel diode, connected in common electrode configuration by a juncture therebetween. A pair of unilaterally conductive paths, each poled to conduct in a direction to maintain current through the switch module which is cut off by turning off the adjacent switch, each connected to an extreme end of the switch module, the other end of said first unilaterally conductive paths being connected together to a first side of a capacitor, the opposite end of the capacitor being connected through a unilaterally conductive path to the juncture between the two switches, said second unilaterally conductive path being poled to conduct current that passes through either of said first paths and said capacitor.

Abstract: An active inductor for controlling transistor bridge switching carrier frequency current components in the power mains connected to a three-phase AC/DC switched bridge converter includes a transformer for each phase, each having a secondary between the AC main and the switched bridge, the primary of which is driven by a bridge switched at much higher frequency in response to a synthesized waveform which ideally will completely cancel the main power bridge switching current components. Reduction of the current carrying requirement of the active inductor is achieved by providing negative feedback of the fundamental power frequency from the primary of each transformer; deviations in the synthesized waveform from the ideal waveform, due to delays and distortions in real circuits and/or processing, are reduced by providing negative feedback from the resultant current (the secondary of the active filter transformer).

Abstract: A hybrid diode/thyristor AC/DC converter includes a thyristor bridge (21) poled oppositely to a diode bridge (13), current through the thyristor bridge being controlled by IGBTs (30, 31). A thyristor turn-off circuit (40-42, 45-47) is responsive to turn-off of the IGBT to reverse bias the thyristors, thereby causing them to turn off. The thyristors and IGBTs are controlled (50) in response to voltage (55-57) of and current flowing (51-53) in the AC mains so as to cause the current flowing to or from the AC mains to be more nearly sinusoidal. The hybrid bridge handles application of regenerative power to the AC mains.

Abstract: Multi-phase power is provided to a load via the use of an inverter which has an even number of inverter legs. DC source voltage, such as from an AC-to-DC converter receiving power from a main AC power supply or from an independent DC power source such as a battery, is provided to the inverter. The DC source voltage is provided on DC bus lines of the inverter so as to be symmetric about ground. Switching devices in the inverter legs are controlled using a modulation strategy to synthesize desired output voltage waveforms on the inverter leg outputs from the voltage on the DC bus lines. The modulation strategy is subject to a modulation constraint such that, at any one time, half of the inverter legs provide a positive output voltage signal with respect to ground, and the other half of the inverter legs provide a negative output voltage signal, of equal magnitude, with respect to ground.