Abstract: A motor drive system for driving a conventional single phase PSC motor from a two-phase power source which allows for convenient motor direction reversal. In one embodiment, the PSC motor is supplied from a three-phase inverter that is controlled to generate two-phase power. In another embodiment, the PSC motor is connectable through a double-pole double-throw switch to either a single phase source including a run capacitor or a two-phase inverter source.

Abstract: A motor drive system for driving a single-phase PSC motor, in which the two motor windings are conductively isolated from each other, from a two phase power source. In one embodiment, the PSC motor is supplied from a two phase inverter circuit. The PSC motor is also connectable through a four-pole double-throw switch to either a single phase source including a run capacitor or the two phase inverter circuit.

Abstract: A motor drive system for driving a conventional single phase PSC motor from a two-phase power source. In one embodiment, the PSC motor is supplied from a three-phase inverter that is controlled to generate two-phase power. In another embodiment, the PSC motor is connectable through a double-pole double-throw switch to either a single phase source including a run capacitor or a two-phase inverter source.

Abstract: A snubber circuit for use with a power seimconductor switching device of a power converting circuit. The snubber circuit includes a snubber capacitor, coupled across the switching device for charging with current bypassing the switching device when the switching device is turned off. The snubber circuit also includes a transformer having a primary winding coupled in series with the snubber capacitor to conduct the flow of current discharged by the snubber capacitor when the switching device is turned on. The snubber circuit further includes an inductor, coupled in series with a secondary winding of the transformer, for regulating the flow of discharged current from the capacitor. The snubber circuit is coupled to return the energy discharged from the snubber capacitor to a power source to which the power converting circuit is coupled.

Abstract: Semiconductor apparatus for mounting and cooling disc type semiconductor devices. The apparatus includes two disc type semiconductor devices each having a pole face thereof in contact with a first terminal bar, that bar in turn being in contact, through thermally conductive electrical insulation, with a water-cooled plate. The opposite pole face of each disc device is in electrical and thermal contact with a first surface of a respective metallic block. A second surface of each block, opposing the first face, is in electrical conductive contact with a second terminal bar. A compressive mounting force is applied across the first and second terminal bars to appropriately compress the disc devices. Each metallic block is sized to absorb a substantial portion of the disc device junction heat generated during a transient portion of a duty cycle, such as may correspond to the starting of a motor.

Abstract: A power regulation system for an AC motor includes a motor terminal box mounted solid state starter having water-cooled SCRs. The SCRs of the starter are cooled by water circulated through a dedicated SCR heat exchanger. The starter mounted in the motor terminal box includes the SCRs configured as an AC switch and a gating circuit for generating gating signals for application to the SCRs.

Abstract: A control circuit for generating gating signals to drive the SCRs of an AC switch coupled between a three phase AC source and a three phase load. A reference voltage signal is derived from the source and, after filtering, is applied to a squaring amplifier. The amplifier output is applied to a phase-locked loop (PLL). The output signal of the voltage controlled oscillator (VCO) of the PLL is fed back to the phase comparator thereof via two dividing counters. The output of one counter is applied to a logic block for generating a ramp reset signal in phase with a selected source phase-to-neutral voltage. The ramp reset signal is applied to a ramp forming circuit the output of which is applied to a first input of a comparator. The comparator receives a DC control voltage on its second input and provides on its output a gating signal corresponding to the source selected phase.