Abstract: In one aspect, a solid-state switching apparatus is provided that includes a pair of anti-parallel thyristors, a quasi-resonant turn-off circuit, a sensor, and a control circuit. The turn-off circuit is coupled in parallel with the pair of anti-parallel thyristors and includes a first selectively conductive path and a second selectively conductive path. The sensor is configured to sense a thyristor current conducted by at least one of the pair of anti-parallel thyristors. The control circuit is configured to receive the sensed thyristor current from the sensor and determine a magnitude of the sensed thyristor current and a polarity of the sensed thyristor current. The control circuit is further configured to activate, in response to determining that the magnitude is greater than a threshold value, one of the first selectively conductive path and the second selectively conductive path based on the polarity to commutate and interrupt the thyristor current.

Abstract: A cooling system for power semiconductor switches is provided. The cooling system includes a heat sink that is pressed against the power semiconductor switch. A plenum is also provided with an opening through a wall thereof which is aligned with the heat sink. A fan draws air through or around the heat sink and through the plenum wall opening and the plenum in order to cool the power semiconductor switch.

Abstract: In one aspect, a solid-state switching apparatus is provided that includes a pair of anti-parallel thyristors, a quasi-resonant turn-off circuit, a sensor, and a control circuit. The turn-off circuit is coupled in parallel with the pair of anti-parallel thyristors and includes a first selectively conductive path and a second selectively conductive path. The sensor is configured to sense a thyristor current conducted by at least one of the pair of anti-parallel thyristors. The control circuit is configured to receive the sensed thyristor current from the sensor and determine a magnitude of the sensed thyristor current and a polarity of the sensed thyristor current. The control circuit is further configured to activate, in response to determining that the magnitude is greater than a threshold value, one of the first selectively conductive path and the second selectively conductive path based on the polarity to commutate and interrupt the thyristor current.

Abstract: A press-pack semiconductor fixture 200 includes a housing defining an interior passage. A first conductor and a second conductor are mechanically coupled with the housing. The mechanical coupling of the first conductor and the second conductor with the housing is effective to apply a clamping force to a press pack semiconductor. A number of apertures or openings are provided in the housing, the first conductor, and the second conductor to permit fluidic flow 290 between the interior passage 239 and spaces or structures exterior to the housing.

Abstract: A press-pack semiconductor fixture 200 includes a housing defining an interior passage. A first conductor and a second conductor are mechanically coupled with the housing. The mechanical coupling of the first conductor and the second conductor with the housing is effective to apply a clamping force to a press pack semiconductor. A number of apertures or openings are provided in the housing, the first conductor, and the second conductor to permit fluidic flow 290 between the interior passage 239 and spaces or structures exterior to the housing.

Abstract: Systems, methods, techniques and apparatuses of ground fault protection are disclosed. One exemplary embodiment is a power switch being structured to receive a load current from a power source at a source-side and selectively output the load current from a load-side to a load; a first voltage measuring device structured to measure a first voltage of the source-side while the power switch is conducting the load current; a second voltage measuring device structured to measure a second voltage of the load-side while the first voltage measuring device is measuring the first voltage; and a controller structured to determine a source-side-to-ground voltage based on the first voltage, determine a load-side-to-ground voltage based on the second voltage, determine a ground fault is occurring, and determine a direction of the ground fault relative to the power switch by comparing the source-side-to-ground voltage and the load-side-to-ground voltage.

Abstract: A cooling system for power semiconductor switches is provided. The cooling system includes a heat sink that is pressed against the power semiconductor switch. A plenum is also provided with an opening through a wall thereof which is aligned with the heat sink. A fan draws air through or around the heat sink and through the plenum wall opening and the plenum in order to cool the power semiconductor switch.

Abstract: A static transfer switch is provided for supplying power to a load alternately from two different power sources. Switching between the two power sources may occur within a fraction of one electrical cycle. In response to sensing degraded performance in the power source supplying the load, a main circuit is turned off with a resonant turn off circuit. The resonant turn off circuit is shared between the main circuits of two different power sources such that the resonant turn off circuit is connected to the main circuit of whichever power source is currently supply power to the load.

Abstract: Systems, methods, techniques and apparatuses of ground fault protection are disclosed. One exemplary embodiment is a power switch being structured to receive a load current from a power source at a source-side and selectively output the load current from a load-side to a load; a first voltage measuring device structured to measure a first voltage of the source-side while the power switch is conducting the load current; a second voltage measuring device structured to measure a second voltage of the load-side while the first voltage measuring device is measuring the first voltage; and a controller structured to determine a source-side-to-ground voltage based on the first voltage, determine a load-side-to-ground voltage based on the second voltage, determine a ground fault is occurring, and determine a direction of the ground fault relative to the power switch by comparing the source-side-to-ground voltage and the load-side-to-ground voltage.

Abstract: A static transfer switch is provided for supplying power to a load alternately from two different power sources. Switching between the two power sources may occur within a fraction of one electrical cycle. In response to sensing degraded performance in the power source supplying the load, resonant turn off circuits connected directly to the main switches of two phases of the power source are actuated to commutate the respective main switches. The main switch of the third phase is commutated with one or more of the resonant turn off circuits through the delta side of a transformer connected to the three phases of the power source.