Abstract: The present invention provides a stack assembly comprising at least one semiconductor device 2a-2d, preferably having an open construction, interspersed between heatsinks 20a-20e and adapted to be at least partially immersed in a liquid dielectric coolant. The open construction means that the at least one semiconductor device 2a-2d will be immersed and flooded in the liquid dielectric coolant. In other words, any spaces or gaps between the various component parts of the at least one semiconductor device 2a-2d will be filled with the liquid dielectric coolant to provide a suitable dielectric environment.

Abstract: The present invention relates to a fuse assembly for rapid interruption of a prospective fault current. The fuse assembly includes a plurality of splitter plates. A plurality of foil elements extend between a pair of terminals and are physically supported by the splitter plates. A pair of parallel busbars are in series with the foil elements and generate a magnetic field that is substantially perpendicular to the current flowing in the foil elements. In the presence of a prospective fault current, the foil elements will melt and at arcing inception an electromagnetic force developed as a result of interaction between the magnetic field and the arc current will push the molten foil elements into the splitter plates. This increases the arc length and hence the arc voltage. At least the foil elements and the splitter plates are preferably located in flowing liquid dielectric such as MIDEL 7131, for example.

Abstract: A circuit for use with a stator winding of a rotating or linear electrical machine, the stator winding having a number of coils linked by the same number of points of common coupling, includes an electronic commutator circuit having the same number of switching stages, each connected between a respective one of the points of common coupling and first and second main dc lines. Each switching stage includes first and second reverse blocking semiconductor power devices. A voltage clamping circuit includes the same number of clamping stages, each connected between a respective one of the points of common coupling and first and second auxiliary dc lines. Each clamping stage includes first and second diodes and first and second capacitors common to the various clamping stages. A dc to dc converter selectively discharges the first and second capacitors to the first and second main dc lines.

Abstract: The electronic commutator circuits provide forced commutation enhancements that can be embedded within a known electronic commutator to overcome its low speed torque limitation. The forced commutation enhancements to the basic switched stage use a pair of thyristors. Capacitors may be pre-charged and synchronized to supplement coil voltages when discharged, thereby reducing commutation overlap duration and maximizing the turn-off time available to allow the thyristors to attain forward blocking capability. A capacitive discharge can be achieved by initiating the capacitive discharge by the same thyristor that will carry the current following the commutation, or by initiating the capacitive discharge by an auxiliary thyristor.

Abstract: A matrix converter that can be used as part of a two-stage power converter has three ac three ac voltage lines AC1, AC2 and AC3 and two dc voltage lines DC1 and DC2. An array of six semiconductor switches 10a to 10f are arranged such that each of the three ac voltage lines AC1, AC2 an AC3 can be connected to one of the two dc voltage lines DC1 and DC2 when the associated switch is closed. A freewheel path is provided between the two dc voltage lines DC1 and DC2, which provides a fifth state of operation when all the switches 10a to 10f are open.

Abstract: An electrical machine, such as an induction motor, comprises a stator having a plurality of conductive windings spaced around an axis of rotation, a rotor rotatable about the axis of rotation in response to the flow of current through the stator windings, and a plurality of switching assemblies provided at circumferentially spaced locations around the stator. Each switching assembly is electrically connected between an end of at least one of the windings and a power supply busbar ring assembly comprising at least one conductor. The busbar assembly connects the electrical supply to one or more of the switching assemblies, each of the switching assemblies being effective to selectively control the supply of current to at least one of the windings.

Abstract: An electrical machine, such as an induction motor, comprises a stator assembly (102) having a plurality of conductive windings (103) spaced around an axis of rotation X-X′, a rotor (101) which is adapted to rotate about the axis of rotation dependent upon the flow of current through the stator windings, and a plurality of switching assemblies (106) provided at circumferentially spaced locations around the stator. Each switching assembly (106) is electrically connected between an end of at least one of the windings and a power supply busbar ring assembly (107) comprising at least one conductor. The busbar assembly connects the electrical supply to one or more of the switching assemblies, each of the switching assemblies being effective to selectively control supply of current to at least one of the windings.