Abstract: A power distribution system includes power converter systems electrically connected to a distribution bus which defines a point of common coupling. Each power converter system includes a power converter with semiconductor switching devices controlled using a pulse width modulation strategy with a switching frequency. A controller for each power converter system applies a spectrum analysis process to the respective power converter system that uses measured or derived zero sequence currents associated with the respective power converter system to determine the location of a ground fault within the power distribution system. Each controller applies a switching frequency process where the switching frequency of the power converter of at least one of the power converter systems is different from the switching frequency of the power converter of at least another one of the power converter systems during at least part of the time that the spectrum analysis process is applied.

Abstract: A DC/DC power converter connected to a DC power source having first and second DC terminals. The DC/DC power converter operates in voltage step-up and step-down modes. The converter includes first and second DC buses connected to the first and second DC terminals and third and fourth DC buses defining a DC link. Energy storage devices are connected between the third and fourth buses. A first converter leg includes a first branch with switches and a second branch. Each switch includes a controllable semiconductor switch and an anti-parallel connected freewheeling diode. A controller switches the controllable semiconductor switches between a conducting and non-conducting state, in the step-up and step-down modes, switching to supply power from the DC power source to the DC link in the step-up mode and to supply power from the DC link to the DC power source in the step-down mode.

Abstract: A power distribution system includes power converter systems electrically connected to a distribution bus which defines a point of common coupling. Each power converter system includes a power converter with semiconductor switching devices controlled using a pulse width modulation strategy with a switching frequency. A controller for each power converter system applies a spectrum analysis process to the respective power converter system that uses measured or derived zero sequence currents associated with the respective power converter system to determine the location of a ground fault within the power distribution system. Each controller applies a switching frequency process where the switching frequency of the power converter of at least one of the power converter systems is different from the switching frequency of the power converter of at least another one of the power converter systems during at least part of the time that the spectrum analysis process is applied.

Abstract: A DC/DC power converter connected to a DC power source/load having first and second DC terminals. The DC/DC power converter operates in voltage step-up and step-down modes. The converter includes first and second DC buses connected to the first and second DC terminals and third and fourth DC buses defining a DC link. Energy storage devices are connected between the third and fourth buses. A first converter leg includes a first branch with switches and a second branch. Each switch includes a controllable semiconductor switch and an anti-parallel connected freewheeling diode. A controller switches the controllable semiconductor switches between a conducting and non-conducting state, in the step-up and step-down modes, switching to supply power from the DC power source/load to the DC link in the step-up mode and to supply power from the DC link to the DC power source/load in the step-down mode.

Abstract: A power converter arrangement is described. The power converter includes a dc link and a power converter. The dc link is operably connected between a generator, or other power source, that provides an output voltage in use and a dc network. The power converter includes an inverter connected across the dc link in parallel with the generator, an isolation transformer having a primary tap changer and a secondary tap changer, and a rectifier. The rectifier has ac terminals connected to the secondary tap changer, a first dc terminal connected to the dc link, and a second dc terminal connected to the dc network. The dc terminal voltage of the rectifier is therefore summated with the output voltage of the generator to provide a converter output voltage.

Abstract: In a marine power distribution and propulsion system with a medium voltage distribution busbar (MVAC1) and a low voltage distribution busbar (LVAC1) then a rectifier (SC) is controlled, optionally to provide active filtering and static compensation benefits. A common power supply system incorporating ac generators (G1-G4) supplies power to the medium and low voltage distribution busbars. The rectifier (SC) is connected to the medium voltage distribution busbar (MVAC1). A controller (Co) uses feedback signals indicative of electrical quantities of the distribution voltages carried by both the medium voltage and low voltage distribution busbars (MVAC1, LVAC1) to control the rectifier (SC) to regulate electrical quantities at the ac terminals of the rectifier (SC) in order to achieve desired electrical quantities of the distribution voltage carried by the low voltage distribution busbar (LVAC1).

Abstract: A semiconductor device or power electronic device is described. The device includes a pair of pole pieces, each having a profiled surface. A semiconductor body or wafer, preferably of wide bandgap electronic material, is located between the pole pieces and includes contact metallization regions. The semiconductor body produces an electric field that emerges from an edge region. Passivation means includes a first or radially inner part in contact with the edge region of the semiconductor body and which diffuses the electric field as it emerges from the edge region and a second or radially outer part. The second part of the passivation is in contact with the first part and provides a substantially void-free interface with the profiled surface of each pole piece. The device may be immersed in a dielectric liquid.

Abstract: A dc electrical machine with a large number of phases. The machine includes a rotor and a stator assembly. The rotor has Np rotating field poles. The stator has Ns winding slots, where Ns/Np is a non-integer ratio. A stator winding includes a plurality of coils received in the winding slots and defines a plurality of stator phases. A power electronic switching assembly includes first and second dc load terminals that can be connected to external equipment and a plurality of switching modules. Each switching module includes power electronic devices and is connected to a respective stator coil. A first proportion of the switching modules are connected together in series between the first and second dc load terminals and a second proportion of the switching modules are connected together in series between the first and second dc load terminals to define two parallel dc circuits.

Abstract: A power converter arrangement is described. The power converter includes a dc link and a power converter. The dc link is operably connected between a generator, or other power source, that provides an output voltage in use and a dc network. The power converter includes an inverter connected across the dc link in parallel with the generator, an isolation transformer having a primary tap changer and a secondary tap changer, and a rectifier. The rectifier has ac terminals connected to the secondary tap changer, a first dc terminal connected to the dc link, and a second dc terminal connected to the dc network. The dc terminal voltage of the rectifier is therefore summated with the output voltage of the generator to provide a converter output voltage.

Abstract: The present invention relates to a vacuum switch assembly for interrupting and isolating fault current. The vacuum switch assembly includes first and second dc lines that, in use, are electrically connected to the dc output terminals of a primary dc power source and a dc network. Each dc line includes at least one vacuum switch having contacts that are opened and closed under the control of a vacuum switch controller. A passive dc power supply unit is electrically connected to the first and second dc lines and includes a secondary dc power source that provides a substantially ripple-free sensing voltage. The vacuum switch controller is adapted to open the vacuum switch contacts when a fault condition (e.g. a fault current or other fault) or an operator request has been identified and when the current flowing between the vacuum switch contacts is below a chopping current associated with the vacuum switches.

Abstract: A converter, and in particular a current source converter, including a bridge having an AC terminal for each of one or more AC lines, and first and second DC terminals. A converter arm is connected between each respective AC terminal and the first DC terminal, and between each respective AC terminal and the second DC terminal. Each converter arm includes a first power semiconductor switching device capable of being turned ‘on’ and ‘off’ by gate control and having a recovery time. The converter is adapted to be operated in one or more inverting modes.

Abstract: A power transmission and distribution system suitable for subsea electrical loads includes a primary dc transmission cable connected to an onshore AC/DC converter module that connects the onshore end of the cable to an ac supply network. The subsea end of the cable is connected to a primary subsea power distribution unit and includes a DC/DC converter module having a modular topology with a series of interconnected DC/DC converter units. The DC/DC converter module is connected between the cable and a primary dc distribution network. Secondary dc transmission cables and associated circuit breakers connect the primary subsea power distribution unit to secondary subsea power distribution units that are located near the subsea loads. Each secondary subsea power distribution unit includes a DC/DC converter module having a modular topology with a series of interconnected DC/DC converter units. Respective secondary dc distribution networks supply power to one or more subsea loads.

Abstract: A fuse assembly for interrupting fault current in an external DC circuit. The fuse assembly includes 2n fusible conductor elements, where n is an integer, wherein the fusible conductor elements extend along, and are circumferentially around, a longitudinal axis of the fuse assembly. The fusible conductor elements are connected together in series to define fuse elements and the fusible conductor elements are orientated within the fuse assembly such that current flowing along each fusible conductor element is in the opposite direction to current flowing along the fusible conductor element or fusible conductor elements adjacent to it. The fuse assembly further includes a supply terminal connected to an end of the fuse element and connectible to a DC supply, and a load terminal connected to an opposite end of the first fuse element and connectible to an electrical load.

Abstract: A converter, and in particular a current source converter, including a bridge having an AC terminal for each of one or more AC lines, and first and second DC terminals. A converter arm is connected between each respective AC terminal and the first DC terminal, and between each respective AC terminal and the second DC terminal. Each converter arm includes a first power semiconductor switching device capable of being turned ‘on’ and ‘off’ by gate control and having a recovery time. The converter is adapted to be operated in one or more inverting modes.

Abstract: The present invention relates to power distribution systems (e.g. a marine power distribution and propulsion system) that include first and second ac distribution busbars. The first ac distribution busbar will typically be a medium voltage busbar for the propulsion drive systems and the second ac distribution busbar will typically be a low voltage for ships services. A 12-pulse rectifier has its ac terminals electrically connected to the first ac distribution busbar. A multiple output generator has first and second galvanically-isolated stator windings. The first stator winding provides a six-phase ac output and is connected to the first ac distribution busbar. The second stator winding provides a three-phase ac output and is connected to the second ac distribution busbar. The six-phase ac output is phase shifted relative to the three-phase ac output to reduce the problematic coupling of harmonic distortion between the first and second ac distribution busbars.

Abstract: An improved rotary switch (e.g. a double pole double break switch) includes first and second poles (2, 4). Each pole including a rotatable bridging member (24) and a pair of fixed busbars (6a, 6b; 8a, 8b). Each busbar has at least one primary contact (14) and may also include a contact arm (12) with an arcing contact (28). The rotary switch is adapted such that the direction of current flow through the first pole (2) is opposite to the direction of current flow through the second pole (4). In this way, arcs established in the first pole (2) are deflected away from arcs established in the second pole (4).

Abstract: A semiconductor device or power electronic device is described. The device includes a pair of pole pieces, each having a profiled surface. A semiconductor body or wafer, preferably of wide bandgap electronic material, is located between the pole pieces and includes contact metallisation regions. The semiconductor body produces an electric field that emerges from an edge region. Passivation means includes a first or radially inner part in contact with the edge region of the semiconductor body and which diffuses the electric field as it emerges from the edge region and a second or radially outer part. The second part of the passivation is in contact with the first part and provides a substantially void-free interface with the profiled surface of each pole piece. The device may be immersed in a dielectric liquid.

Abstract: The present invention relates to a vacuum switch assembly for interrupting and isolating fault current. The vacuum switch assembly includes first and second dc lines that, in use, are electrically connected to the dc output terminals of a primary dc power source and a dc network. Each dc line includes at least one vacuum switch having contacts that are opened and closed under the control of a vacuum switch controller. A passive dc power supply unit is electrically connected to the first and second dc lines and includes a secondary dc power source that provides a substantially ripple-free sensing voltage. The vacuum switch controller is adapted to open the vacuum switch contacts when a fault condition (e.g. a fault current or other fault) or an operator request has been identified and when the current flowing between the vacuum switch contacts is below a chopping current associated with the vacuum switches.

Abstract: In a marine power distribution and propulsion system with a medium voltage distribution busbar (MVAC1) and a low voltage distribution busbar (LVAC1) then a rectifier (SC) is controlled, optionally to provide active filtering and static compensation benefits. A common power supply system incorporating ac generators (G1-G4) supplies power to the medium and low voltage distribution busbars. The rectifier (SC) is connected to the medium voltage distribution busbar (MVAC1). A controller (Co) uses feedback signals indicative of electrical quantities of the distribution voltages carried by both the medium voltage and low voltage distribution busbars (MVAC1, LVAC1) to control the rectifier (SC) to regulate electrical quantities at the ac terminals of the rectifier (SC) in order to achieve desired electrical quantities of the distribution voltage carried by the low voltage distribution busbar (LVAC1).

Abstract: The present invention provides an electronic commutator circuit for use with a stator winding of an electrical machine. The stator winding of the electrical machine includes a number of coils linked by the same number of points of common coupling. The electronic commutator circuit comprising the same number of switching stages, each switching stage being connected between a respective one of the points of common coupling and first and second dc terminals. Each switching stage further includes a first reverse blocking semiconductor power device (such as a Reverse Blocking Gate Turn Off Thyristor (RB-GTO 1) capable of being turned on and off by gate control having its anode connected to the first dc terminal, and a second reverse blocking semiconductor power device (RB-GTO 2) capable of being turned on and off by gate control having its cathode connected to the second dc terminal.