Abstract: A transverse flux electrical machine for coupling to a rotating shaft of a propulsor of an aircraft is provided. The transverse flux electrical machine includes a rotor having a plurality of circumferentially distributed permanent magnets that form a number, NP, of rotor poles, wherein the rotor poles have a pole pitch angle, P?, equal to 2? divided by the number of rotor poles, NP. The transverse flux electrical machine further includes a stator having a plurality of current-carrying coils configured to interact with the rotor poles of the rotor to produce a torque. The transverse flux electrical machine further includes an air gap separating the rotor from the stator by an air gap distance, GAir, wherein a machine parameter, ?, defined as: ?=P?×GAir is less than 100 micro radian-meters.

Abstract: An electrical machine for an aircraft electrical power system includes a stator having current-carrying coils and flux guiding stator iron defining one or more stator slots that house the current-carrying coils. The electrical machine further includes a rotor having a plurality of permanent magnets configured to interact with the stator to produce a torque. The electrical machine has an active parts mass, mact, which is a cumulated mass of components of the electrical machine that contribute to producing the torque. The electrical machine is configured to produce a peak rated torque, ?peak. The electrical machine has a slot current density, Jslot,peak, when producing the peak rated torque, ?peak. A value of a machine parameter, ?, defined as: ?=?peak/(mact×Jslot,peak) is greater than or equal to 5 ?Nm3 kg?1A?1.

Abstract: A vertical take-off and landing (VTOL) aircraft includes at least one electrical propulsion unit (EPU). An EPU of the at least one EPU includes a propeller or a fan and a transverse flux electric motor. The electric motor includes a stator having coils configured to carry current and a rotor arranged to interact with the stator, such that a torque for driving rotation of the propeller or the fan is generated. The rotor is configured to supply a flow of air to the coils, such that heat is removed from the coils. The coils are directly exposed to the flow of air, such that heat is exchanged directly from the coils to the flow of air. Each coil includes an effective cooling surface area directly exposed to the flow of air. An effective cooling surface area is at least 20% of a total surface area of the respective coil.

Abstract: A vertical take-off and landing (VTOL) aircraft includes at least one electrical propulsion unit (EPU). An EPU of the at least one EPU includes a propeller or a fan and a transverse flux electric motor. The electric motor includes a stator having coils configured to carry current and a rotor arranged to interact with the stator, such that a torque for driving rotation of the propeller or the fan is generated. The rotor is configured to supply a flow of air to the coils, such that heat is removed from the coils. The coils are directly exposed to the flow of air, such that heat is exchanged directly from the coils to the flow of air. Each coil includes an effective cooling surface area directly exposed to the flow of air. An effective cooling surface area is at least 20% of a total surface area of the respective coil.

Abstract: An AC to DC conversion device has first and second AC input terminals arranged to be coupled respectively to first and second terminals of a phase of an AC current generator, an H-bridge rectification device comprising two pairs of diodes, each pair being coupled to a respective one of the AC terminals to produce a DC output comprising a rectified back EMF waveform, and a waveform generator. The waveform generator comprises an output coupled to the DC output of the H-bridge rectification device, and is configured to input a unidirectional waveform to the DC output having the same magnitude and fundamental frequency as the rectified back EMF, phase shifted by a predetermined angle relative to the rectified back EMF waveform.

Abstract: A transverse flux electric motor includes a stator including coils configured to carry current and a rotor arranged to interact with the stator. The rotor is configured to produce a torque for driving rotation of the rotor. The transverse flux electric motor has an active parts mass, mact, equal to a cumulated mass of components of the transverse flux electric motor that contribute to the production of the torque. The transverse flux electric motor has an active parts torque density, ?act, defined as a peak rated torque, ?peak, divided by the active parts mass, mact. The transverse flux electric motor has a power factor equal to cos(?), wherein ? is a steady-state phase difference between a stator coil current and a stator coil voltage, and wherein the transverse flux electric motor has a machine parameter ? that is greater than or equal to 65 Nmkg?1, where ? equals ?act/cos(?).

Abstract: A vertical take-off and landing (VTOL) aircraft is provided. The VTOL aircraft includes at least one electrical propulsion unit (EPU), wherein an EPU of the at least one EPU includes a propeller or a fan. The EPU further includes an electric motor including a stator having insulated coils for carrying current and a rotor arranged to interact with the stator, such that a torque for driving rotation of the propeller or the fan is produced.

Abstract: Integrated arrangements of electrical machines and power electronics converters are described. One such arrangement comprises: an electrical machine comprising one or more windings; a power electronics converter arranged to supply current to or receive current from the one or more windings of the electrical machine; a magnetocaloric effect (MCE) material in thermal contact with the power electronics converter; and a heat sink for removing heat from the MCE material. The MCE material is arranged in proximity to the one or more windings of the electrical machine whereby, in use, stray magnetic flux from the windings of the electrical machine passes through the MCE material and activates the MCE material. The repeated application and removal of the stray flux during normal operation of the electrical machine creates cycles of magnetic refrigeration, which removes heat from the power electronics converter.

Abstract: The disclosure relates to an electrical power system for connecting an electrical machine to first and second DC networks operating at different voltages. Example embodiments include an electrical power system comprising: an electrical machine having first and second pluralities of windings; a first AC:DC power electronics converter connected to the first plurality of windings; a second AC:DC power electronics converter connected to the second plurality of windings; a switching controller configured to provide switching signals to the first and second AC:DC power electronics converters to provide a first DC supply at a DC side of the first AC:DC power electronics converter and a second DC supply at a DC side of the second AC:DC power electronics converter.

Abstract: An electrical power system for an aircraft includes a DC:AC power electronics converter and a transverse flux electrical machine. The transverse flux electrical machine includes a rotor that is coupleable to a rotating shaft of a propulsor of the aircraft, wherein the rotor includes a plurality of permanent magnets defining a number, NP, of evenly distributed rotor poles. The transverse flux electrical machine further includes a stator arranged to interact with the rotor, such that a torque is produced. The stator includes a plurality of coils.

Abstract: An electrical propulsion unit (EPU) for a vertical take-off and landing (VTOL) aircraft is provided. The EPU includes a propeller or a fan and an electric motor. The electric motor includes a stator comprising coils configured to carry current and a rotor arranged to interact with the stator. The rotor is configured to generate a torque for driving rotation of the propeller or the fan. The coils of the stator have a cumulated conductor volume Vconductor The stator, the rotor, or the stator and the rotor include a flux guiding iron material configured to guide magnetic flux generated by the coils of the stator, wherein the flux guiding iron material has a cumulated iron volume Viron, and wherein the electric motor has a machine parameter ? that is greater than or equal to 0.25, ? being defined as: ?=Vconductor/Viron.

Abstract: The disclosure relates to an electric aircraft propulsion assembly comprising: an electric storage unit; a first electric motor connected to power a first propulsor; a first converter configured as a DC:AC converter having input connections connectable to the electric storage unit and output connections connected across the first electric motor, the first converter configured as a DC:AC converter; a second electric motor connected to power a second propulsor; a second converter connected between the first converter input connections and the second electric motor; and a controller configured to control operation of the first and second converters, wherein the second converter is operable as a DC:AC converter to convert the DC supply from the electric storage unit to an AC supply across the second electric motor and as a DC:DC converter to convert the DC supply from the electric storage unit at a first DC level to a DC supply at the input connections of the first converter at a second DC level.

Abstract: The disclosure relates to an electric aircraft propulsion assembly for an electric vertical takeoff and landing, eVTOL, aircraft, the assembly comprising: an electric storage unit; a first electric motor connected to power a first propulsor; a first converter configured as a DC:AC converter for driving the first electric motor and a second electric motor connected to power a second propulsor, a second converter. A controller is connected to control operation of the first and second converters and is configured to operate in a first mode in which the first and second converters are operated as DC:AC converters to drive the first and second electric motors and a second mode in which the first converter is operated to drive the first electric motor to power the first propulsor and the second converter is operated to drive the second electric motor to provide a braking torque on the second propulsor.

Abstract: An electric machine comprises a stator winding located within a stator housing. The stator housing comprises an inlet chamber configured to communicate with a supply of coolant, and an outlet. The stator housing contains a baffle configured to separate the stator winding and outlet from the inlet chamber. The baffle includes at least one aperture therethrough configured to supply an impingement flow of coolant to the stator winding.

Abstract: An AC to DC conversion device has first and second AC input terminals arranged to be coupled respectively to first and second terminals of a phase of an AC current generator, an H-bridge rectification device comprising two pairs of diodes, each pair being coupled to a respective one of the AC terminals to produce a DC output comprising a rectified back EMF waveform, and a waveform generator. The waveform generator comprises an output coupled to the DC output of the H-bridge rectification device, and is configured to input a unidirectional waveform to the DC output having the same magnitude and fundamental frequency as the rectified back EMF, phase shifted by a predetermined angle relative to the rectified back EMF waveform.

Abstract: A radial flux rotary electric machine having an exterior-rotor configuration is shown. The machine has a permanent-magnet rotor comprising permanent magnets in a Halbach array, and an air-cored stator interior to the rotor having teeth defining tapered slots and distributed windings around the teeth to form coils in a double-layer arrangement, the windings being comprised of a plurality of phase windings. For each tooth T having a slot S1 on one side thereof and a slot S2 on another side thereof, a coil side C1 of a phase winding is arranged to occupy a radially inner layer of the slot S1 and a coil side C2 of the same phase winding is arranged to occupy a radially outer layer of the slot S2, wherein the coil side C1 has a smaller circumferential dimension and a larger radial dimension than the coil side C2.

Abstract: Integrated arrangements of electrical machines and power electronics converters are described. One such arrangement comprises: an electrical machine comprising one or more windings; a power electronics converter arranged to supply current to or receive current from the one or more windings of the electrical machine; a magnetocaloric effect (MCE) material in thermal contact with the power electronics converter; and a heat sink for removing heat from the MCE material. The MCE material is arranged in proximity to the one or more windings of the electrical machine whereby, in use, stray magnetic flux from the windings of the electrical machine passes through the MCE material and activates the MCE material. The repeated application and removal of the stray flux during normal operation of the electrical machine creates cycles of magnetic refrigeration, which removes heat from the power electronics converter.

Abstract: The dual rotor electric machine comprises: a stator having one or more slots and one or more stator windings. The dual rotor electric machine further comprises a first rotor arranged to rotate relative to the stator with an airgap therebetween. The first rotor comprises a first rotor excitation element having one or more magnetic pole pairs arranged to interact with the stator windings, the first rotor configured to rotate about an axis (X). The dual rotor electric machine further comprises a second rotor arranged to rotate relative to the stator with an airgap therebetween. The second rotor comprises a second rotor excitation element having one or more magnetic pole pairs arranged to interact with the stator windings, the second rotor being configured to rotate about the axis (X).

Abstract: An electric machine (101) for use in an aircraft is shown. The electric machine comprises a casing (104) containing electromechanical components, a shaft (106) which extends outside of the casing, a seal (107) to seal the casing around the shaft, and a pressurisation system (102) configured to pressurise the casing above an external pressure to prevent electrical breakdown within gas in the casing.

Abstract: An electric machine (212) comprises a turbomachine rotor (203) having a hub (302) and an axis of rotation (A-A) about which the turbomachine rotor is arranged to rotate. The turbomachine rotor includes a plurality of blades (301). Each blade has a root (303) attached to the hub, a tip (304) remote from the hub, a leading edge (305) and a trailing edge (306), a pressure side and a suction side (307). A stator (502) is located circumferentially around the turbomachine rotor. Each blade further comprises a rotor element at the tip comprising a permanent magnet having a first pole (401) and a second pole (402), the first pole being located adjacent the suction side of the blade and the second pole being located adjacent the pressure side such that a magnetic flux path extends perpendicularly through the blade tip.