A high reliability AC load switching circuit is disclosed. In some embodiments, the AC load switching circuit includes a high-speed switch connected between the load and the voltage source, a cutoff switch connected between the load and the voltage source in parallel with the high-speed switch, and a level detector connected to the voltage source and to a control input of the high-speed switch. The high-speed switch may be a solid-state switch, for example, a TRIAC or a bidirectional switch, and the cutoff switch may be an electromechanical switch, for example, a relay. In some embodiments a snubber is connected in parallel with a solid-state switch. In some embodiments a microcontroller is connected to an eletromechanical switch and the level detector. In some embodiments, both a first cutoff switch and a second cutoff switch are used.

A switch device includes first and second switch units that are coupled respectively to first and second output terminals. Each of the first and second switch units includes a plurality of diodes and at least one semiconductor-controlled rectifier (SCR), where at least one of the diodes and one of the at least one SCR cooperatively permit a current to flow therethrough to a corresponding one of the first and second output terminals when each thereof operates in an ON state, and where at least one of the diodes and one of the at least one SCR cooperatively permit a current to flow therethrough from a corresponding one of the first and second output terminals when each thereof operates in an ON state.

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.

A DC switching device has at least one switching unit which is arranged between two terminals. Further, the DC switching device has a control unit for controlling the at least one switching unit. The switching unit has a first and a second semiconductor switching element, which are arranged in parallel with one another, the first switching element being a high-voltage switching element and the second switching element being a low-power-loss switching element. The switching unit is controllable by the control unit in such a way that, when the switching unit is switched off, initially the second switching element is switched to be non-conductive, and subsequently the first switching unit is switched to be non-conductive, and when the switching unit is switched on, initially the first switching element is switched to be conductive and subsequently the second switching element is switched to be conductive.

An electric power conversion circuit includes: first through fourth port terminals; a first diode having an anode connected to the first port terminal; a second diode having a cathode connected to the second port terminal; a third diode having a cathode connected to the first port terminal; a fourth diode having an anode connected to the second port terminal; first through fourth switches that are bridge-connected between a cathode of the first diode and an anode of the second diode; fifth through eighth switches that are bridge-connected between an anode of the third diode and a cathode of the fourth diode; a first bootstrap circuit that is connected to control terminals of the first through fourth switches; and a second bootstrap circuit that is connected to control terminals of the fifth through eighth switches.

Embodiments of a transistor control device for controlling a bi-directional power transistor are disclosed. In an embodiment, a transistor control device for controlling a bi-directional power transistor includes a resistor connectable to a body terminal of the bi-directional power transistor and a transistor body switch circuit connectable to the resistor, to a drain terminal of the bi-directional power transistor, and to a source terminal of the bi-directional power transistor. The transistor body switch circuit includes switch devices and alternating current (AC) capacitive voltage dividers connected to control terminals of the switch devices. The AC capacitive voltage dividers are configured to control the switch devices to switch a voltage of the body terminal of the bi-directional power transistor as a function of a voltage between the drain terminal of the bi-directional power transistor and the source terminal of the bi-directional power transistor.

The present disclosure provides a debounced solid state switching device comprised of at least two insulated-gate bipolar transistors (“IGBTs”) within a parallel architecture. Multiple pairs of IGBTs may be used in a parallel architecture to extend ampacity and improve voltage withstand capability. The device provides improved flexibility and portability to facilitate time and cost efficiency, as the size and complexity of the device is directly dependent on the needs of the user. Furthermore, the procurement of the components of the device is simple, providing greater accessibility.

An electric assembly includes a reverse conducting switching device and a rectifying device. The reverse conducting switching device includes transistor cells for desaturation configured to be, under reverse bias, turned on in a desaturation mode and to be turned off in a saturation mode. The rectifying device is electrically connected anti-parallel to the switching device. In a range of a diode forward current from half of a maximum rating diode current of the switching device to the maximum rating diode current, a diode I/V characteristic of the rectifying device shows a voltage drop across the rectifying device higher than a saturation I/V characteristic of the switching device with the transistor cells for desaturation turned off and lower than a desaturation I/V characteristic of the switching device with the transistor cells for desaturation turned on.

A bidirectional switch fault protection circuit includes a bidirectional switch circuit, a desaturation detection circuit, and a gate driver. The bidirectional switch circuit generates first and second switch voltages based on a direction of electric current. The desaturation detection circuit outputs the first switch voltage in response to the electric current flowing in a first direction and outputs the second switch voltage in response to the electric current flowing in a second direction opposite the first direction. The gate driver receives the first switch voltage in response to the electric current flowing in the first direction and the second switch voltage in response to the electric current flowing in the second direction. The gate driver detects a first short circuit condition based on the first switch voltage and a second short circuit condition based on the second switch voltage.

Described herein are multiple designs for an improved analog switch for use in transmitting high voltage signals without using high voltage power supplies for the switch. The analog switches are able to pass and block input signals in the approximate range of −100 V to +100 V. The use of translinear loops and a bootstrap configuration results in a constant on-resistance of the symmetrical switches and matches the conductance of each analog switch to the transconductance of an NMOS transistor, which can be easily stabilized with a constant g.sub.m biasing scheme. In certain embodiments, a shunt termination (T-switch) configuration is used for better off-isolation, and each of the symmetrical switches has its own translinear loop and thus flexibility of on-resistance and termination voltage.