Otis Elevator Company

Alexander L Julian

Joseph DiTucci

Giovanna Oriti

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. Upon cutoff of one of said switches, current flows through one of said first unilaterally conductive paths, said capacitor, and said second unilaterally conductive path and through the antidiode of the other of said switches. Since the voltage across the capacitor is always opposite to the conductivity of the unilaterally conductive paths with which it is in series, the capacitor of one such clamp can be connected in parallel with the capacitor of other clamps, and the voltage thereacross regulated by a single regulator, such as a resistor fed through a solid state switch controlled by a threshold detector.

Clamped bidirectional power switches

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).

Active filtering of AC/DC switched converter input current

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.

Growing community of inventors

Vernon, CT, United States of America

Alexander L Julian