Electric motors for propeller engines

Abstract

A system is provided that includes a brushless DC ("BLDC") electric motor for a propeller engine and a motor controller. The motor includes a rotor comprising one or more permanent magnets and one or more alternator windings, and a stator comprising one or more stator windings. The controller is configured to apply a first transient DC voltage to the windings of the stator, wherein the first transient DC voltage is configured to provide commutation switching to the windings of the stator to generate torque on the rotor. The controller is also configured to apply a second static DC voltage to the windings of the stator, wherein the second static DC voltage is configured to induce current in the alternator windings to generate an AC voltage in the alternator windings.

Description

Technical Field

[0001] The present disclosure generally relates to an electric motor for an aircraft propeller. Background Art

[0002] An electric (e.g., DC) motor is configured to convert electrical current (electrical energy) into mechanical energy by passing current through one or more windings, each of which generates a magnetic field. One or more permanent magnets are used to generate one or more secondary magnetic fields, and due to the interaction between the magnetic fields, a reciprocating force is generated between the windings on one side and the magnets on the other side.

[0003] A mechanical commutator can be used to energize the windings in the armature of a DC motor. However, it is becoming increasingly common to use an electrical mechanism (so-called brushless DC motors, or BLDCs) to replace such mechanical commutators. While permanent magnets typically form part of the motor's stator (and the windings of the rotor), with electrical commutation, the windings can form part of the stator, and the permanent magnets can form part of the rotor. Stationary windings can be configured to move the permanent magnets (and the rotor) by being energized in a controlled sequence to produce a rotating magnetic field.

[0004] A typical sequence is Figure 1 This is shown in Figure 1 and can be referred to as a trapezoidal control scheme, in which fixed windings are energized in a specific order to drive the motor. A three-phase brushless DC motor 2 (shown schematically and electrically) is driven counterclockwise by a motor controller 1 (which can be a MOSFET bridge). For each step in the commutation sequence, one of the windings ("U," "V," or "W") is driven high by the controller 1, while another is driven low, and the third is left floating. For example, in the upper left diagram, winding U is high (forming a north pole), winding V is low (forming a south pole), and winding W is left floating. The resulting magnetic field is configured to move the rotor counterclockwise, as its permanent magnets are repelled by one winding and attracted by the next. The subsequent stage (below) shows winding U held high while windings are switched to floating and winding W is switched low. This can be viewed as maintaining the rotation of the magnetic field and moving the rotor. The remaining commutation steps follow a similar sequence.

[0005] Various other arrangements for electric brushless DC motors are available and known in the art, such as sinusoidal or field-oriented control. In sinusoidal control, all three windings are kept constant, with the drive current in each winding following a sinusoidal curve at 120 degrees from each other. Field-oriented control relies on measuring and adjusting conditions so that the angle between the rotor and stator fluxes is always 90 degrees. The motor controller (e.g., Figure 1Motor controllers 1 can each use various sensors, such as Hall-effect sensors, to determine the position of the rotor relative to the stator. This can be used to determine switching points or changes in current flow as the rotor rotates. Furthermore, pulse width modulation can be used to convert the input DC voltage into a modulated drive voltage. Such techniques are well known in the art and will not be discussed in detail herein.

[0006] Medium-sized propeller aircraft are typically equipped with a single powerplant on each wing. The propellers used on such aircraft are typically variable-pitch to allow operation at a substantially constant, predetermined RPM, and also to generate reverse thrust or tilt the propeller to reduce windmilling drag and prevent any risk of overspeed. On existing aircraft, pitch changes can be achieved using electro-hydraulic mechanical systems. The power required for such systems can be approximately 1-4% of the total power output of each powerplant.

[0007] Modern propellers may additionally include a blade de-icing system, which may include a heater in the form of a resistive element that covers or extends along the bottom of the propeller blade trailing edge. Such heaters typically require an electrical power supply, either three-phase AC or single-phase DC, and typically require approximately 1-4% of the total power output of each powerplant.

[0008] Both variable pitch mechanisms and de-icing mechanisms for the propeller blades require various components to be mounted on the rotating propeller, resulting in the need to transmit electrical or hydraulic power from the powerplant or the stationary side of the aircraft to the rotating propeller. Electrical power transmission can be achieved using brush contacts and slip ring mechanisms, but this can be weighty or costly, and can also wear out over time. Hydraulic power transmission can be achieved using transfer bearings, which also have the disadvantages of weighty or costly, as well as introducing potential leakage issues.

[0009] Recent trends in aircraft propulsion systems include the desire to incorporate electric propulsion as part (or all) of the engine powerplant on an aircraft, wherever possible. This leads to various considerations regarding how to make existing variable pitch, de-icing, and other systems work with electric propulsion mechanisms, and the technology disclosed herein is intended to address such considerations. Summary of the Invention

[0010] In one aspect of the present disclosure, a system is provided that includes a brushless DC ("BLDC") electric motor for a propeller engine (and / or for driving multiple propellers) and a motor controller. The motor includes a rotor that can be configured to rotate about an axis, wherein the rotor includes one or more permanent magnets and one or more alternator windings, and the motor also includes a stator that includes one or more stator windings. The controller is configured to apply a first transient DC voltage to the stator windings, wherein the first transient DC voltage is configured to provide commutation switching to the stator windings to generate torque on the rotor via the permanent magnets. The controller is also configured to apply a second static DC voltage to the stator windings, wherein the second static DC voltage is configured to induce a current in the alternator windings to generate an AC voltage in the alternator windings.

[0011] The above arrangement advantageously avoids the need for a slip ring assembly between the static and rotating portions of the motor (or propeller engine), reducing complexity, weight, and cost. Furthermore, a single motor (and, equally importantly, a single controller) can be used to provide rotational drive to the propeller of the propeller engine and to generate electrical power on the rotating side of the engine to power variable pitch, de-icing, and other systems on the rotating side. Therefore, the technology disclosed herein is particularly applicable to direct-drive propeller engines in which an electric motor directly drives the rotating portion of the engine (i.e., without the use of a gear assembly), and various aspects relate to direct-drive propeller engines including the above-described system.

[0012] The term "propeller engine" is intended to refer to the engine assembly as a whole, including, for example, the propeller, propeller hub, drive unit (in this case, the electric motor), and various other components. The term "propeller engine assembly" may be used interchangeably with this term.

[0013] Furthermore, an important feature of this system is that it allows the motor controller to be mounted on the static part (aircraft side), which avoids the high G field constraints associated with mounting on the rotating part (i.e., with the propeller). This also allows for easy electrical connection to the aircraft power grid and other aircraft systems such as the flight control computer.

[0014] According to any of the aspects and embodiments described herein, the alternator windings and / or permanent magnets may be distributed around the circumference of the rotor and may rotate about a common axis (eg, the above-mentioned axis of rotation of the rotor).

[0015] The stator can include a hub (or shaft), and the magnetic elements can extend from the hub (e.g., in pairs with opposing relationships). Stator windings can be wound around each magnetic element. Each magnetic element can extend from the hub in opposite directions to another (e.g., opposing) magnetic element.

[0016] The permanent magnets may include alternating north and south poles located around the circumference of the rotor.

[0017] The alternator windings can be located circumferentially between two (or more) permanent magnets on the rotor. This can provide a compact assembly and optimize the electrical layout of the alternator windings and permanent magnets. Alternatively, the alternator windings can be located concentrically within the permanent magnets on the rotor, such that the permanent magnets form a cylindrical assembly at a first radial position, while the alternator windings are located at a second radial position within (or outside) the cylindrical assembly of permanent magnets. In other embodiments, the permanent magnets and alternator can be axially displaced.

[0018] According to any of the aspects and embodiments described herein, the system can further include one or more position sensors configured to generate signals indicating the position of the permanent magnets and / or the alternator windings. The controller can be configured to receive the signals from the position sensors and process the signals to determine the relative positions of the stator windings and the permanent magnets and / or the alternator windings. The controller can be configured to use the relative positions determined from the signals to provide commutation switching for the stator windings and generate torque on the rotor as described above.

[0019] In one aspect, a propeller engine is provided that includes the system described in any of the above aspects and embodiments, wherein the motor is configured to drive a propeller of the propeller engine. The propeller can be driven directly by the motor, e.g., without the use of a gear assembly and / or reduction gearing and / or drive shaft. In this case, the stator can advantageously be mounted directly in the propeller hub and attached directly to the aircraft structure, thereby reducing the number of components (and therefore weight and cost).

[0020] The controller can be configured to control the speed of a propeller (e.g., one or more propellers) and the power supplied by the alternator. The controller can, for example, vary both the speed and the power based on the engine thrust demand and the power demand, respectively. The controller can receive the engine thrust demand from an external device, such as a command signal from an engine management system (e.g., controlled by an operator or pilot). The controller can determine the electrical power demand from a feedback mechanism of an electric power system powered by the alternator (e.g., one or more of the electric power systems described below and elsewhere herein). The controller can be configured to regulate a first static DC voltage supplied to the alternator coils. The controller can optionally determine the electrical power demand from the alternator using one or more sensors configured to generate a signal representing an AC or DC current and / or voltage generated by the alternator. The controller can regulate the first static DC voltage supplied to the alternator coils based on the determined demand.

[0021] The engine may further include a rotating portion including a rotor and a plurality of propellers and a non-rotating portion including a stator, wherein the rotating portion of the engine may further include one or more electric power systems. The one or more electric power systems may include one or more of a system for changing propeller pitch and / or a system for de-icing the propellers.

[0022] The engine may further include a magnetic coupling between the stationary portion and the non-rotating portion, wherein the magnetic coupling is configured to transmit one or more signals between the stationary portion and the non-rotating portion. The controller may be configured to send and receive signals to and from one or more power supply systems located on the non-rotating portion via the magnetic coupling. Similarly, the one or more power supply systems may be configured to send and receive signals to and from the controller via the magnetic coupling. The controller and the one or more power supply systems may communicate via the magnetic coupling. The magnetic coupling may include existing components of the assembly, such as stator windings and alternator windings.

[0023] In the operating mode, the controller can also be configured to generate power in the alternator windings by applying AC voltage to the stator windings, but without commutation switching or other variability that would drive the rotor to rotate. This operating mode is useful for changing the pitch on the propellers if the rotor is not rotating, such as when the aircraft is on the ground.

[0024] In one aspect, an aircraft is provided that includes a propulsion system comprising one or more propeller engines, at least one of which (or all of which) is a propeller engine as described in any one of the aspects and embodiments described above.

[0025] In one aspect, an unmanned aerial vehicle ("UAV") is provided that includes a propulsion system comprising one or more propeller engines, at least one of which (or all of which) is a propeller engine as described in any of the aspects and embodiments described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Various embodiments will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0027] Figure 1 shows the commutation sequence of a conventional brushless DC electric motor;

[0028] Figure 2 An aircraft having twin propeller engines according to various embodiments of the present disclosure is shown;

[0029] Figure 3 A propeller engine according to various embodiments of the present disclosure is shown, which can be used with Figure 2 used with aircraft; and

[0030] Figure 4 An electric motor according to various embodiments of the present disclosure is schematically shown and can be used with Figure 3 Used together with propeller engines. DETAILED DESCRIPTION

[0031] In the meantime, various embodiments of electric motors or machines for aircraft (also referred to herein as an aeroplane) will be described. The aircraft can be of the type that is propelled (e.g., in any direction, including forward, backward, upward, downward, or sideways) by thrust from one or more propeller engines (e.g., fixed-wing or rotary-wing), and the electric motor can be configured to drive one of the propeller engines. In various embodiments, each propeller engine can be configured to be driven by one such electric motor.

[0032] The aircraft can have any suitable size, shape, and wing configuration. The aircraft can be used for one or more of performance, cargo and / or personnel transportation, military, and research. The aircraft can be an aircraft piloted by a pilot on board the aircraft, or can be an unmanned aerial vehicle ("UAV"), such as a drone, that can be controlled remotely or by a computer. Vertical lift propulsion systems can benefit from the propeller engines disclosed herein, and aspects of the present disclosure can relate to vertical lift propulsion systems that include the propeller engines and electric motors described herein.

[0033] The technology disclosed herein may be particularly applicable to unmanned aerial vehicles and / or propeller-driven aircraft. In particular, aircraft powered by one or more propeller assemblies (where electric power and / or electromechanical systems are located on the rotating portion of the propeller assembly) may benefit from the technology disclosed herein, such as variable pitch and / or de-icing systems or any other electrical systems.

[0034] The electric motor described herein is intended to combine a brushless DC ("BLDC") electric motor and an alternator in a common assembly for driving an aircraft propeller.

[0035] Figure 2 An aircraft 10 is shown including a fuselage 12 and a pair of fixed wings 14 extending from the fuselage 12. Located on each wing is a propeller engine 16, each propeller engine being configured to drive a propeller assembly including a plurality of propellers 18.

[0036] Figure 3The propeller engine 16 is shown isolated and schematically, from which a propeller 18 can be seen extending from a rotating propeller hub 20. The engine 16 includes an electric motor 30 that is configured to rotate the propeller 18 to provide thrust to the aircraft 10. Although there may be a drive shaft between the electric motor 30 and the propeller 18, in various embodiments the motor 30 is mounted in the propeller hub 20 to eliminate the need for this additional assembly. One or more bearings 31 or bearing systems may be provided to allow the propeller hub 20 (and other rotating parts of the engine) to rotate relative to the stationary parts of the engine 16.

[0037] The engine 16 may also include a motor controller 100 (eg, a processor or circuit) configured to control the operation of the electric motor 30. Figure 3 The controller 100 is shown as being incorporated within the engine 16, but this is not the case and the controller 100 may be incorporated remotely, for example as part of an engine management system of the aircraft 10. The engine management system may be located anywhere on the aircraft 10, such as in the cockpit, or even (for example, in the case of an unmanned aerial vehicle) remotely from the aircraft.

[0038] The broadest aspect of the present disclosure may relate to a system including a brushless DC (“BLDC”) electric motor 30 and a controller 100 .

[0039] The engine 16 may also include one or more power sources 102, such as one or more batteries, fuel cells, or an auxiliary power unit utilizing a heat engine.

[0040] Engine 16 may also include one or more electrical power systems 24 located on a rotating portion of the propeller assembly, such as within propeller hub 20. The one or more electrical power systems 24 may include one or more of a system 26 for changing the pitch of propeller 18 and / or a system 28 for de-icing the propeller and / or any other system 18.

[0041] Figure 4 One embodiment of the electric motor 30 (or electric motor system) disclosed herein is schematically shown and may be used in Figure 2 and Figure 3 The electric motor 30 includes a rotating portion 40 (or rotor) and a static portion 42 (or stator).

[0042] The electric motor 30 includes a plurality of permanent magnets 32, including a first permanent magnet 32A and a second permanent magnet 32B. The first permanent magnet 32A may be a "north-seeking" magnet, while the second permanent magnet 32B may be a "south-seeking" magnet. In the illustrated arrangement, the permanent magnets 32 are configured to rotate with the rotating portion 40 about the central axis A (e.g., with the propeller hub 20).

[0043] The electric motor 30 also includes an alternator 34 comprised of a pair of alternator windings 34A, 34B wound around respective magnetic poles 35, which may be made of any suitable magnetic material, such as iron (e.g., sheet metal or plate iron). In this arrangement, the alternator 34 is configured to rotate with the permanent magnets 32 as part of the rotating portion 40 of the electric motor 30. While a pair of alternator windings 34A, 34B are shown, any number of windings may be used, and the present disclosure is not limited to the use of two windings.

[0044] The alternator windings 34A, 34B and permanent magnets 32 may be distributed around the circumference of the rotating portion 40 and may be stacked in a tiled manner (eg, rotated about a common axis such as the central axis A).

[0045] The alternator 34 and / or alternator windings 34A, 34B may be configured to generate electrical power that may be used to power one or more electric power and / or electromechanical systems 24 , such as the variable pitch 26 and / or de-icing system 28 or any other electrical system located on the rotating portion 40 .

[0046] Positioning the permanent magnets 32 and the alternator 34 as part of the rotating portion 40 eliminates the need to transmit electricity from the static portion 42 of the motor 30 via electrical connections such as brushes and slip rings and hydraulic connections for powering components or one or more electro-dynamic and / or electro-mechanical systems associated with the rotating portion 40, such as a variable pitch and / or de-icing system or any other electrical system.

[0047] The static portion 42 of the electric motor 30 includes a hub (or shaft) 44 from which opposing magnetic elements 46 may extend (ie, extend in opposite directions), with a plurality of windings 48A, 48B wound around each magnetic element 46 .

[0048] Number of windings on the static part 42 ( Figure 4 Two are shown, namely 48A and 48B, and can be changed as needed. For example, the number of windings can generally be related to the number of phases in the electric motor, such as six windings for a three-phase motor. Static portion 42 can be located in the center of the motor and can be attached to a structure (e.g., engine 16), which in turn can be attached to or integrated with a fixed wing of the aircraft (e.g., wing 14).

[0049] The permanent magnets 32 may include alternating north and south poles located around the circumference of the rotating portion 40 (relative to the axis A). Figure 3 As shown, the rotating part 40 can be mounted on Figure 3 The permanent magnets 32 are mounted in the propeller 18 of the engine 16 and can be mounted in the propeller hub 20 or in the body of the engine 16 itself. In any case, the permanent magnets 32 rotate with the propeller 18 of the engine 16.

[0050] The alternator 34 includes alternator windings 34A, 34B distributed around a circumference (relative to axis A), wherein the number of windings of the alternator 34 may be a multiple of the number of phases of the alternator, such as a three-phase alternator with 6 windings.

[0051] The electric motor 30 may also include various position sensors 50 configured to generate signals indicating the position of one or more components of the rotating portion 40, such as the permanent magnets 32 and / or the alternator 34. The controller 100 may receive the signals and may be configured to determine the relative positions of the components of the rotating portion 40 and the static portion 42. This helps the controller 102 send appropriate electrical signals to the windings 48A, 48B of the motor 30. The position sensors 50 may be located on the static portion 42, simplifying signal transmission to the controller 100. While they could be located on the rotating portion 40, this may make communication with the controller 100 more difficult.

[0052] As shown in the illustrated embodiment, the permanent magnets 32 and the alternator 34 are stacked in a tile shape and share the same axis of rotation A. In various embodiments, the permanent magnets 32 and the alternator 34 can be axially displaced while still using a common static portion 42 as a drive element. Both of these embodiments can be referred to as radial flux arrangements. In various embodiments, the structural elements described herein can be used in conjunction with an axial flux arrangement. In this case, the permanent magnets 32 and the alternator 34 can be stacked in a tile shape or concentrically, wherein the alternator windings 34A, 34B can be mounted on an inner periphery inside the outer periphery of the permanent magnets, which can maximize the electric motor torque.

[0053] The controller 100 may be similar to conventional control for a brushless DC motor (e.g., as described above with respect to Figure 1 4 and 5. The rotatable portion 40 is operative as described above to provide commutation switching of the windings 48A, 48B of the static portion 42 such that torque is generated on the rotating portion 40 and causes the rotating portion 40 to rotate about the axis A.

[0054] To achieve this, the controller 100 can apply a first transient and / or variable DC voltage (e.g., from the power supply 102) to the windings 48A, 48B of the static portion 42. The transient or variable DC voltage is sequentially applied to the windings 48A, 48B to generate a north-seeking or south-seeking magnetic field for driving the rotating portion 40. As described above, the controller 100 can apply the transient or variable DC voltage with a trapezoidal, sinusoidal, or field-oriented control scheme. The controller can be configured to position the field with sufficient offset to generate the appropriate magnetic force to rotate the rotating portion 40.

[0055] The transient or variable DC voltage is intended to cause a fixed north-seeking or south-seeking magnetic pole to be generated on the windings 48A, 48B of the static portion 42 relative to the permanent magnets 32, regardless of the rotational speed of the motor 30. In this manner, the controller 100 can be configured to vary the motor torque, and thereby the rotational speed of the propeller 18, by varying the DC current applied to the windings 48A, 48B.

[0056] The controller 100 can be configured to apply a second static (or constant) DC voltage to the windings 48A, 48B to generate a constant north-seeking or south-seeking magnetic field across each winding 48A, 48B. These constant magnetic fields can be configured to augment or subtract from the fields generated by applying the transient or varying DC voltages described above. The magnetic field generated by the static DC voltage will rotate relative to the rotating portion 40 and the alternator 34, resulting in a variable magnetic flux seen by the windings 34A, 34B, which induces current in these windings 34A, 34B (i.e., the windings of the alternator 34) to generate an AC voltage within the alternator 34. The AC voltage will be proportional to the DC voltage applied to the windings 48A, 48B of the static portion 42 and may also be a function of the number of phases and / or poles, as well as the RPM (rotational speed) of the rotating portion 40 (and, for example, its propeller 18).

[0057] The single-phase or multi-phase AC voltage generated in the alternator 34 can then be rectified to DC. Current and / or voltage sensor(s) (not shown) can be used to feed signals representing the AC or DC current and / or voltage back to the controller 100 (located on the static portion 42), thereby allowing closed-loop regulation of the generated voltage / current based on power demand. This can be achieved by controlling a second static (or constant) DC voltage applied to the stator's magnetic coils (a signal transmission solution will be described below).

[0058] Thus, in various embodiments, the controller 100 can be configured to regulate the first quiescent DC voltage supplied to the coils based on the demand for electrical power from the alternator 34, optionally using one or more sensors configured to generate signals representative of the AC or DC current and / or voltage generated by the alternator 34. As described above, this provides a beneficial closed-loop regulation.

[0059] It has been recognized that there is a large ratio between the power required to drive the rotation of propeller 18 and the power required to power the electric and / or electromechanical systems 24 (e.g., variable pitch mechanism 26 and / or de-icing system 28) on the rotating components of engine 16. This leads to the development of the first and second DC voltages as described above, which allow motor 30 to provide both electrical power to electric and / or electromechanical systems 24 and rotational drive to engine 16 in an energy-efficient manner.

[0060] In various embodiments, the magnetic coupling between the rotating portion 40 and the non-rotating portion 42 can be used to transmit wireless signals between the rotating portion and the non-rotating portion of the engine 16 (in both directions), for example using high-frequency AC modulation. The engine 16 can include a magnetic coupling between the static portion 40 and the non-rotating portion 42 (using, for example, the windings 34A, 34B of the alternator 34 and the windings 48A, 48B of the static portion 42), wherein the magnetic coupling is configured to transmit one or more signals (which may be the wireless signals mentioned above) between the static portion 40 and the non-rotating portion 42. The controller 100 can be configured to send and receive these signals to and from one or more electric power systems located on the non-rotating portion 42 via the magnetic coupling. Similarly, the one or more electric power systems can be configured to send and receive signals to the controller 100 via the magnetic coupling. The controller 100 and the one or more electric power systems can communicate via the magnetic coupling.

[0061] In the operating mode, the controller can also be configured to generate power in the alternator windings by applying AC voltage to the stator windings, but without commutation switching or other variability that would drive the rotor to rotate. This operating mode is useful for changing the pitch on the propellers if the rotor is not rotating, such as when the aircraft is on the ground.

[0062] It will be appreciated that the present technology eliminates the need for electrical or hydraulic supply lines between the rotating and static or non-rotating portions of the propeller engine, which would otherwise be necessary to provide de-icing and variable pitch propellers. Weight and cost are also reduced because the electric motor 30 has a common static portion 42 for driving both the alternator 34 and the rotating portion 40 of the motor 30.

[0063] While the present disclosure has been described with reference to various embodiments, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the scope of the present invention as set forth in the following claims.

Claims

1. A system for a propeller engine (16) comprising a brushless DC electric motor (30) and a motor controller (100), wherein the electric motor (30) comprises: a rotor (40) comprising one or more permanent magnets (32) and one or more alternator windings (34A, 34B); and a stator (42) comprising one or more stator windings (48A, 48B), wherein the motor controller (100) is configured to apply a first transient DC voltage to the windings (48A, 48B) of the stator (42), wherein the first transient DC voltage is configured to provide commutation switching to the windings (48A, 48B) of the stator (42) to generate torque on the rotor (40), The motor controller (100) is further configured to apply a second static DC voltage to the windings (48A, 48B) of the stator (42), wherein the second static DC voltage is configured to induce a current in the alternator windings (34A, 34B) to generate an AC voltage in the alternator windings (34A, 34B).

2. The system of claim 1, wherein the alternator windings (34A, 34B) and permanent magnets (32) are distributed around the circumference of the rotor (40) and rotate about a common axis (A).

3. The system of claim 1 or 2, wherein the stator (42) includes a hub (44) and magnetic elements (46) extending from the hub (44), wherein the stator winding (48A, 48B) is wound around each magnetic element (46).

4. The system of claim 3, wherein each magnetic element (46) extends from the hub (44) in an opposite direction from another magnetic element (46).

5. The system of any one of claims 1, 2, and 4, wherein the permanent magnets (32) include alternating north and south poles located around the circumference of the rotor (40).

6. The system of any one of claims 1, 2, and 4, wherein the alternator windings (34A, 34B) are located circumferentially between two or more of the permanent magnets (32) of the rotor (40).

7. The system of any one of claims 1, 2, and 4, wherein the alternator windings (34A, 34B) are concentrically located within the permanent magnets (32) of the rotor (40).

8. The system of any one of claims 1, 2, and 4, further comprising one or more position sensors (50) configured to generate a signal indicative of the position of the permanent magnet (32) and / or the alternator winding (34A, 34B).

9. The system of claim 8, wherein the motor controller (100) is configured to receive the signals from the position sensor (50) and process the signals to determine the relative positions of the stator windings (48A, 48B) and the permanent magnets (32) and / or the alternator windings (34A, 34B).

10. The system of any one of claims 1, 2, 4 and 9, wherein the permanent magnets (32) and the alternator (34) are axially displaced.

11. A propeller engine (16) comprising the system according to any one of claims 1 to 10, wherein the electric motor (30) is configured to drive the propeller engine (16).

12. The propeller engine according to claim 11, further comprising: a rotating portion, the rotating portion including the rotor (40) and a plurality of propellers (18); and a non-rotating portion including the stator (42), wherein the rotating portion of the propeller engine (16) further includes one or more electric power systems (24).

13. The propeller engine according to claim 12, wherein the one or more electric power systems include one or more of a system (26) for changing the pitch of the propeller (18) and / or a system (28) for de-icing the propeller.

14. An aircraft comprising one or more propeller engines, at least one of said propeller engines being a propeller engine according to claim 11, 12 or 13.

15. An unmanned aerial vehicle comprising one or more propeller engines, at least one of the propeller engines being a propeller engine according to claim 11, 12 or 13.

Images