Abstract: The disclosure relates to an electrical power system with current fault protection provided by current limiting diodes. Example embodiments include an electrical power system comprising: an electrical machine; an AC:DC power electronics converter connected to receive an input AC supply from the electrical machine and provide an output DC supply across first and second output terminals; a DC bus connected to first and second output terminals of the AC:DC power electronics converter; a load connected across the DC bus; a first circuit breaker switch and a first current limiting diode connected in series between the AC:DC power electronics converter and the DC bus; and a second circuit breaker switch and a second current limiting diode connected in series between the DC bus and the load, wherein the first current limiting diode is configured to limit current to a higher level than the second current limiting diode.

Abstract: Reconfigurable permanent magnet electrical machines and aircraft power and propulsion systems including the electrical machines. An aircraft power and propulsion system includes: a gas turbine engine; DC electrical network; permanent magnet electrical machine including a rotor drivingly coupled to a spool of the engine, and a stator including windings controllably switchable between a star and a delta configuration; an AC-DC power electronics converter, an AC side is connected to terminals of the stator windings and a DC side is connected to the DC electrical network; an additional electrical power source connected to and controllable to supply electrical power to the DC electrical network; and a control system configured to control the switching of the stator windings between the configurations and to control the additional electrical power source to supply electrical power to the DC electrical network during a time interval when the stator is being switched between the configurations.

Abstract: The disclosure relates to an electrical power system for providing a stabilised DC voltage to a power bus. Example embodiments include an electrical power system comprising: a DC power bus having first and second DC power bus terminals; an electrical storage unit having first and second terminals, the second terminal connected to the second DC power bus terminal; a DC:DC converter having first and second DC:AC converters and a transformer connected between the first and second DC:AC converters, the first DC:AC converter connected between the first terminal of the electrical storage unit and the first DC power bus terminal; and a controller connected to control a switching operation of one or both of the first and second DC:AC converters.

Abstract: The disclosure relates to an electrical power system for connecting an electrical machine to first and second DC networks operating at different voltages. In an embodiment, an electrical power system comprises: an electrical machine having first, second, third and fourth windings; first, second, third and fourth AC:DC power electronics converters each connected to receive an input AC supply from the respective first, second, third and fourth windings, each AC:DC power electronics converter having first and second DC output terminals connecting the AC:DC power electronics converters to first, second and third DC supply output terminals, wherein the first and second windings are arranged to provide an AC supply to the respective first and second AC:DC power electronics converters in quadrature to each other and the third and fourth windings are arranged to provide an AC supply to the respective third and fourth AC:DC power electronics converters in quadrature to each other.

Abstract: An electrical power system including: an electrical power source, a power electronics converter, an electrical network, a current limiting diode and a controllable circuit interruption device, wherein: the current limiting diode is configured to limit a fault current passing between the electrical power source and the electrical network in a fault condition; and the controllable circuit interruption device is configured to interrupt the fault current in response to a determination that the electrical power system is in the fault condition.

Abstract: The disclosure relates to an electrical power system for providing a stabilised DC voltage to a power bus. Example embodiments include an electrical power system comprising: a DC power bus having first and second DC power bus terminals; an electrical storage unit having first and second terminals, the second terminal connected to the second DC power bus terminal; a DC:DC converter having first and second DC:AC converters and a transformer connected between the first and second DC:AC converters, the first DC:AC converter connected between the first terminal of the electrical storage unit and the first DC power bus terminal; and a controller connected to control a switching operation of one or both of the first and second DC:AC converters.

Abstract: An electrical power system including: an electrical power source, a power electronics converter, an electrical network, a current limiting diode and a controllable circuit interruption device, wherein: the current limiting diode is configured to limit a fault current passing between the electrical power source and the electrical network in a fault condition; and the controllable circuit interruption device is configured to interrupt the fault current in response to a determination that the electrical power system is in the fault condition.

Abstract: There is provided a current limiting diode comprising a gate, a source, and a drain electrically connected to the source by an n-channel or p-channel; wherein the source and the gate are electrically connected by a fill structure comprising a phase-change fill material, and wherein the phase-change fill material is configured to absorb heat from the n-channel or p-channel by changing phase.

Abstract: A fuel and oil system includes a fuel pump, an oil pump, and a fixed electrical drive. A first electric motor controller of the fuel and oil system supplies a variable electrical drive, and a second electric motor controller supplies a variable electrical drive. The fuel pump is selectively connected to and driven by the first electric motor controller or the second electric motor controller. The oil pump is selectively connected to and driven by the second electric motor controller or the fixed electrical drive.

Abstract: An engine system comprises first and second electrical generators coupled to lower and higher pressure (LP, HP) shafts respectively of a gas turbine engine. A controller is arranged to receive a signal corresponding to a total electrical power demand P1 and to output control signals to the electrical generators in response thereto such that the first and second electrical generators output electrical powers (1?y)P1 and yP1 respectively when P1?Pm1, where 0.5<y?1 and Pm1 is the maximum electrical output power of the first electrical generator. By satisfying the demand P1 mostly by extraction of electrical power from the first electrical generator when possible, the additional mechanical stress on the gas turbine engine resulting from electrical power extraction is reduced compared to the case where 50% or more of the demand P1 is satisfied by the second electrical generator.

Abstract: An engine system comprises first and second electrical generators coupled to lower and higher pressure (LP, HP) shafts respectively of a gas turbine engine. A controller is arranged to receive a signal corresponding to a total electrical power demand P1 and to output control signals to the electrical generators in response thereto such that the first and second electrical generators output electrical powers (1?y)P1 and yP1 respectively when P1?Pm1, where 0.5<y?1 and Pm1 is the maximum electrical output power of the first electrical generator. By satisfying the demand P1 mostly by extraction of electrical power from the first electrical generator when possible, the additional mechanical stress on the gas turbine engine resulting from electrical power extraction is reduced compared to the case where 50% or more of the demand P1 is satisfied by the second electrical generator.

Abstract: A fuel and oil system comprising a fuel pump; an oil pump. A first electric motor controller configured to supply a variable electrical drive. A second electric motor controller configured to supply a variable electrical drive. A fixed electrical drive. The fuel pump is selectively connected to and driven by the first electric motor controller or the second electric motor controller. The oil pump is selectively connected to and driven by the second electric motor controller or the fixed electrical drive.