Integrated electric propulsion unit

Abstract

An integrated electric propulsion unit includes a housing, an alternating current motor, a beta bar, a propeller, a speed governor, an inverter, and a controller. The alternating current motor is disposed within the housing and includes a plurality of bearings supported within the housing, a hollow motor shaft rotatably coupled to the housing by the plurality of bearings, a stator supported by the housing, and a rotor mounted to the hollow motor shaft. The beta bar is axially translatable inside the hollow motor shaft. The propeller is mechanically coupled to the hollow motor shaft. The propeller includes propeller blades having an adjustable pitch angle dependent on an axial position of the beta bar. The speed governor is configured to adjust the pitch angle of the propeller blades by actuating the axial translation of the beta bar. The inverter is disposed within the housing and connected to receive direct current power for conversion to alternating current power. The controller is disposed within the housing and configured to control operation of the inverter and to control the pitch angle of the propeller blades.

Description

Technical Field

[0001] This disclosure generally relates to electric propulsion units for aircraft. Some aircraft have electric propulsion systems (hereinafter referred to as "electric aircraft"). In such aircraft, an electric motor converts electrical electricity into mechanical power for use by the propulsion system. For example, an electric motor can rotate one or more thrusters on the aircraft to provide thrust. Electric aircraft can take various forms. For example, an electric aircraft can be an airplane, a rotorcraft, a helicopter, a quadcopter, an unmanned aerial vehicle, or some other suitable type of aircraft. Background Technology

[0002] Typical electric propulsion solutions rely on discrete, integrated components assembled together to form an electric propulsion system. As used herein, the modifier “integrated” when applied to components of a component means that these components are designed independently of each other. The motor and inverter are integrated components, requiring dedicated mechanical structures, dedicated cooling circuits, and complex electrical and control interfaces. The inverter needs to be located very close to the motor within the nacelle environment. The mechanical installation of the inverter and motor is a challenging task due to the small nacelle size and the installation constraints of wiring for cooling channels, heat exchangers / air ducts, electrical wires, and control lines.

[0003] Traditional solutions primarily consist of separate inverters, motors, and drive components, with numerous electrical and cooling interfaces in between. Most electric propulsion components are separate entities—motors, power electronics, transmissions, and batteries—packaged much like traditional turbine propulsion systems. Attempting to integrate individual electrified drivetrain components is complex, expensive, and time-consuming. Electric propulsion systems are complex systems, creating significant integration challenges within the cabin and aircraft fuselage. Developing optimized integration solutions that mechanically integrate components within the cabin will reduce weight and cost. Summary of the Invention

[0004] The subject matter disclosed below relates to an integrated electric propulsion unit that offers reduced weight and cost compared to aircraft propulsion systems composed of multiple components. This system includes a simplified cooling system with a single loop for housing all components (motors, inverters, thrust bearings, governors, etc.) within the cabin. The system design simplifies the integration of electrical components, allows for a reasonable number of electrical connections, simplifies electromagnetic interference (EMI) filtering, simplifies electrical wiring harnesses, and reduces the number of switchboards. The propulsion control system is also integrated to reduce the number of controllers and simplify control wiring harness design.

[0005] In the context of the fluid transport system described below, the term "channel" refers to a hollow body comprising a conduit for guiding the flow of fluid from an opening at one end of the conduit to another opening at the other end. The opening through which fluid enters the conduit is referred to herein as an "inlet"; the opening through which fluid exits the conduit is referred to herein as an "outlet." Examples of channels disclosed herein include pipes, tubes, cooling plates, cooling jackets, and internal channels in solids. In the context of the motor controller described below, the term "channel" refers to an inverter consisting of a set of power switches controlled by an inverter controller. For example, a motor controller with three inverters is described as having three channels, which supply phase-controlled AC power to the same motor. Although various embodiments of integrated electric propulsion units for aircraft will be described in considerable detail below, one or more features of those embodiments may be present in one or more of the following aspects.

[0006] One aspect of the subject matter disclosed below is an electric propulsion unit comprising: a housing; an AC motor disposed within the housing and including a plurality of bearings supported within the housing, via which a hollow motor shaft, a stator supported by the housing, and a rotor mounted to the hollow motor shaft are rotatably connected; a β-rod axially translatable within the hollow motor shaft; a thruster mechanically connected to the hollow motor shaft, the thruster including thruster blades having an adjustable pitch angle depending on the axial position of the β-rod; a speed controller configured to adjust the pitch angle of the thruster blades by actuating the axial translation of the β-rod; an inverter disposed within the housing and connected to receive DC power for converting it into AC power; and a controller disposed within the housing. The controller is configured to perform operations including: controlling the operation of the inverter; and controlling the pitch angle of the thruster blades.

[0007] Another aspect of the subject matter disclosed below is an electric propulsion unit, comprising: a housing; an AC motor disposed within the housing and including a plurality of bearings supported within the housing, a motor shaft rotatably connected to the housing via the plurality of bearings, a stator supported by the housing, and a rotor mounted to the motor shaft; an inverter disposed within the housing and connected to receive DC power for converting it into AC power; a controller disposed within the housing and configured to control the operation of the inverter; and a cooling circuit configured to guide the flow of circulating fluid. The cooling circuit includes: an oil tank mounted to the housing; a cooling pump mounted to the housing, geared to the motor shaft and in fluid communication with the oil tank; and a cooling channel disposed inside the housing and connected to guide circulating fluid from the cooling pump toward the oil tank along a flow path. The cooling circuit typically also includes a heat exchanger.

[0008] Another aspect of the subject matter disclosed below is an electric propulsion system comprising a first battery configured to generate direct current (DC) power, a first DC power input line connected to the first battery, and an electric propulsion unit connected to the first DC power input line. The electric propulsion unit includes: a housing; an AC motor disposed within the housing and including a plurality of bearings supported within the housing, a motor shaft rotatably coupled to the housing via the plurality of bearings, a stator supported by the housing, and a rotor mounted to the motor shaft; a thruster mechanically coupled to the motor shaft; a first electromagnetic interference (EMI) filter disposed within the housing and connected to receive DC power from the first battery via the first DC power input line; a first DC bus disposed within the housing and connected to the first EMI filter; a plurality of first inverters disposed within the housing, each of the plurality of first inverters connected to the first DC bus; and a controller disposed within the housing and configured to control the operation of the plurality of first inverters.

[0009] Another aspect of the subject matter disclosed below is an electric propulsion unit, comprising: a housing; an AC motor disposed within the housing and including a plurality of bearings supported within the housing, a motor shaft rotatably connected to the housing via the plurality of bearings and having an axis of rotation, a stator supported by the housing, and a rotor mounted to the motor shaft; a main drive gear mounted to the front end of the motor shaft and having teeth; a thruster including a hollow thruster shaft having an axis of rotation and thruster blades having an adjustable pitch angle, the axis of rotation being offset from the axis of rotation of the motor shaft; a β rod axially translatable within the hollow thruster shaft; a speed controller configured to adjust the pitch angle of the thruster blades by actuating the axial translation of the β rod; a thruster shaft drive gear mounted to the hollow thruster shaft and having teeth meshing with the teeth of the main drive gear; a plurality of power modules disposed radially outward from the stator; and a controller disposed within the housing. The controller is configured to perform operations including: controlling the operation of the plurality of power modules; and controlling the pitch angle of the thruster blades.

[0010] Another aspect of the subject matter disclosed below is an electric propulsion unit comprising: a housing; a plurality of first bearings and a plurality of second bearings supported within the housing; a main drive shaft supported by the plurality of first bearings and the plurality of second bearings supported within the housing; a first hollow motor shaft and a second hollow motor shaft surrounding corresponding sections of the hollow main drive shaft; a first pair of mechanical couplings and a second pair of mechanical couplings selectively connecting the first hollow motor shaft and the second hollow motor shaft to the main drive shaft, respectively; a first rotor and a second rotor, respectively mounted to the first hollow motor shaft and the second hollow motor shaft; a first stator and a second stator supported within the housing and respectively disposed radially outside the first rotor and the second rotor; a thruster mechanically coupled to the main drive shaft; and a controller disposed within the housing and configured to selectively actuate a pair of mechanical couplings to disengage one hollow motor shaft from the main drive shaft.

[0011] Other aspects of the integrated electric propulsion unit for aircraft are disclosed below. Attached Figure Description

[0012] The features, functions, and advantages discussed in the foregoing sections can be implemented independently in various embodiments, or can be combined in other embodiments. To illustrate the above and other objectives, various embodiments will be described below with reference to the accompanying drawings.

[0013] Figure 1 This is an illustration showing an overview of an electric propulsion unit with integrated mechanical, cooling, and electrical / control components.

[0014] Figure 2 This is an illustration showing an overview of an electric propulsion unit with mechanical, cooling and electrical / control integration according to one embodiment.

[0015] Figure 3 This is an illustration showing the mechanical components of the electric propulsion unit integrated in a single package directly connected to the main structure of the aircraft.

[0016] Figure 4 This is a diagram illustrating the integration of the cooling, lubrication, and governor oil components of an electric propulsion unit into a single liquid system.

[0017] Figure 5 This is a diagram showing the integrated air cooling of the motor and inverter of the electric propulsion unit.

[0018] Figure 6 This is a diagram illustrating the integration of electrical and control components of an electric propulsion unit.

[0019] Figures 7A to 7D This is an illustration showing an example implementation of a motor / inverter cooling integration and speed controller / pump solution.

[0020] Figure 8A This is an illustration showing an overview of an electric propulsion unit with multi-channel integration according to another embodiment.

[0021] Figure 8B It shows the use of Figure 8A The diagram shows an integrated multiphase fault-tolerant motor design for an electric propulsion unit.

[0022] Figure 9A This is an illustration showing a partial cross-sectional view of a dual-motor electric propulsion unit with integrated transmission system according to another embodiment.

[0023] Figure 9B It means Figure 9A An illustration of an end view showing the concentric shaft arrangement in a dual-motor electric propulsion unit.

[0024] Figure 9C This shows the integration of the drivetrain in Figure 9A The diagram shows a dual-motor electric propulsion unit.

[0025] The following reference will be made to the accompanying drawings, in which similar elements in different drawings have the same reference numerals. Detailed Implementation

[0026] An illustrative embodiment of an integrated electric propulsion unit for an aircraft is described below in considerable detail. However, not all features of an actual implementation are described in this specification. Those skilled in the art will understand that in the development of any such embodiment, many implementation-specific decisions must be made to achieve the developer's specific objectives, such as compliance with system-related and business-related constraints that vary from one implementation to another. Furthermore, it should be understood that such development work can be complex and time-consuming, but is merely a routine task for those of ordinary skill in the art who will benefit from this disclosure.

[0027] For illustrative purposes, a system for distributing load power drawn from multiple batteries to power the propulsion of an electric aircraft is described below. However, the technology presented herein is not limited to its application in aircraft, but can also be applied to the propulsion of other types of electric vehicles, such as automobiles, industrial trucks, and trains.

[0028] Figure 1This is an illustration of components identifying a typical electric propulsion unit 100 (hereinafter referred to as "Unified EPU 100") with combined mechanical, cooling, and electrical / control components. The Unified EPU 100 is partially formed by a multi-channel motor controller (MC) that converts direct current (DC) power to alternating current (AC). Each channel of the motor controller includes a corresponding inverter 50 controlled by a corresponding inverter controller 5. Each inverter 50 is preceded by a corresponding electromagnetic interference (EMI) filter 24 (and possibly other front-end circuitry). The Unified EPU 100 also includes an AC motor 30 that receives AC power from the inverter 50 via multiple or more sets of AC power lines 6. The Unified EPU 100 also includes a thruster 32 driven to rotate by the AC motor 30. The thruster 32 includes a thruster shaft 34 mechanically coupled to the output shaft of the AC motor 30 and multiple thruster blades 36. The thruster shaft 34 is coupled to a thrust bearing 38 to form a thrust bearing / thruster shaft assembly 70. The combined EPU 100 also includes a governor 42 (also known as a propeller governor), configured to maintain a constant rotational speed of the propeller 32 by changing the pitch angle (hereinafter referred to as "pitch") of the propeller blades 36. This is achieved by the hydraulic governor using hydraulic valves to control the flow of engine oil through a hydraulic mechanism in the propeller 32. A controller integrated within the governor is configured to control the flow of hydraulic valves ( Figure 1 Engine oil flow (not shown). When it is desired to reduce the blade pitch, the hydraulic valve opens, and pump 40c (together with third manifold 54c and oil tank 46c) increases the oil pressure to provide a rapid and positive response through thruster 32. Depending on its position, the hydraulic valve directs oil flow to the thruster (increasing pitch), allows flow back from the thruster (decreasing pitch), or remains in an intermediate position with no oil flow (constant pitch) in a known manner.

[0029] exist Figure 1 In the example shown, inverter 50 forms three motor controller channels for supplying alternating current to corresponding sets of star-connected windings 26 (hereinafter referred to as "motor star windings 26") in the stator 25 of AC motor 30. Each inverter 50 includes a corresponding set of power switches, which are cooled by liquid coolant supplied via a corresponding cooling pipe 9 connected to manifold 54a. The power switches of each inverter 50 are electrically connected to corresponding sets of stator windings in AC motor 30. Inverter 50 also includes sensors ( Figure 1(Not shown in the image), which measures the voltage and current of the AC power signal output by inverter 50 and feeds this sensor data back to the corresponding inverter controller 5. The operation of the inverter is controlled by inverter controller 5. More specifically, the switching state of each set of power switches (e.g., MOSFETs) is controlled by the corresponding inverter controller 5, which sends a gate drive signal to the gate of the semiconductor power switch. In this way, inverter 50 can operate in different phases to convert DC power into multiphase AC power for AC motor 30. Figure 1 In the example shown, AC motor 30 is a 3×3 phase AC motor. Controller 5 controls the operation (switching) of inverter 50.

[0030] exist Figure 1 In the system shown, the HVDC power source is battery 18. For example, battery 18 may comprise multiple battery modules arranged in parallel or series between the positive and negative buses to form a battery pack. Each battery module is a separate battery. Figure 1 Parallel / series arrangement (not shown). Each battery module can be monitored by an associated module monitoring unit (…). Figure 1 (Not shown in the image) Monitoring. The HVDC power supply also includes a battery management system 22 configured to manage the operation of battery 18. Each module monitoring unit in battery 18 transmits sensor data representing virtual battery voltage and individual battery temperature to the battery management system 22. The battery management system 22 also receives data from a current sensor (…). Figure 1 (Not shown in the image) receives data. The system also includes a DC-DC voltage conversion subsystem (…). Figure 1 (Not shown in the image), which is configured to receive high-voltage DC power from battery 18 via a battery contactor and convert the high-voltage DC power into low-voltage DC power for use in the system or other (non-propulsion) components in the broader vehicle platform. Figure 1 The system shown also includes a power distribution board 20. The power distribution board 20 includes an HVDC bus 4 connected to a DC power input line 8 via a corresponding bus contactor 16. The DC power input line 8 delivers HVDC power from the DC voltage conversion subsystem to a corresponding channel of the inverter 50. The battery 18, the DC voltage conversion subsystem, and the power distribution board 20 can be mounted in the fuselage 102 (or possibly in the wing), while the DC power input line 8 passes through the wing 104. Due to space and bending radius constraints, routing separate power and control lines to separate inverters is difficult. Additional power distribution boards are needed to distribute the battery output into multiple channels to accommodate multiple inverter inputs or additional power sources, such as additional batteries, generators, or fuel cells.

[0031] The Joint EPU 100 also includes a thermal management system 108, configured to cool the inverter 50 and cool and lubricate the motor 30 and thrust bearing / propeller shaft assembly 70. The thermal management system 108 includes a heat exchanger 56 that receives cooling air 62 (from...) when the aircraft is propelled forward. Figure 1 (Indicated by the arrow pointing to the left in the diagram). Heat exchanger 56 is configured such that cooling air 62 extracts heat from the liquid coolant returned by inverter 50, motor 30, and thrust bearing / propeller shaft assembly 70 via a separate cooling circuit. Figure 1 In the example shown, the cooling circuit includes dedicated combined pumps 40a-40d and oil tanks 46a-46c.

[0032] More specifically, the cooling circuit 50 for the inverter includes a pump 40a and an oil tank 46a, which are in fluid communication (via cooling pipes or channels) with the heat exchanger 56 and the first manifold 54a. Liquid coolant circulates from the first manifold 54a through corresponding cooling plates within each inverter 50 (these plates are thermally coupled to cool the power switches in each inverter) and then returns to the first manifold 54a. The pump 40a is driven by a motor 44a that receives AC power from the inverter 45a.

[0033] The cooling / lubrication circuit for motor 30 includes pump 40b and oil tank 46b, which are in fluid communication with heat exchanger 56 and second manifold 54b (via cooling / lubrication pipes or channels). Liquid coolant / lubricant circulates from second manifold 54b through stator 25 and through thrust bearing / propeller shaft assembly 70, and then returns to second manifold 54b via cooling pipes or channels. Pump 40b is driven by motor 44b, which receives AC power from inverter 45b.

[0034] Cooling / lubrication piping needs to be routed from two separate cooling circuits to each inverter and motor star winding. The number of cooling pipes and the wiring with two different circuit types create complexity and integration challenges. Installing dedicated pumps and tanks for each circuit adds to the complexity and challenges of nacelle integration. The thrust bearing / propeller shaft assembly 70 and governor 42 are joint components, requiring dedicated mechanical structures and cooling / lubrication circuits. Thrust bearing 38 mechanically decouples motor 30 from propeller 32. Thrust bearing 38 requires a lubrication system that can be connected in parallel with the motor cooling system and an additional dedicated scavenging pump 40d. Typically, governor 42 is used to control propeller pitch via a hydraulic actuator / β-bar system. This system requires a high-pressure oil system supplied by an additional pump 40c and tank 46c.

[0035] like Figure 1As shown, the system also includes an engine control unit 10 (hereinafter referred to as "ECU 10") installed in the engine compartment. ECU 10 is connected to an inverter controller 5 within the inverter 50. The inverter controller 5 is communicatively connected to receive control signals from and send feedback signals to the ECU 10, performing a supervisory and coordinating role over all inverter controllers 5. ECU 10 is also communicatively connected to an electric propulsion controller 12 (hereinafter referred to as "EPC 12"), which controls… Figure 1 The diagram shows the overall operation of the aircraft's electric propulsion motor drive system.

[0036] EPC 12 receives commands from flight control computer 14, which in turn receives pilot thrust and pitch inputs from thrust control stick 21 and pitch control stick 23 located in the cockpit. EPC 12 also receives commands from speed and position sensors ( Figure 1 (Not shown) receives a signal proportional to the thruster's rotational speed. Additionally, EPC 12 receives a signal from a current sensor (…). Figure 1 (Not shown) Receives a signal representing the measured current. EPC 12 sends commands to engine control unit 10 for controlling inverter operation based on information from sensors and pilot input. EPC 12 is also connected to battery management system 22. EPC 12 is configured to send a digital torque command signal 51 to engine control unit 10 and an analog pitch command signal 52 (e.g., feathering command) to governor 42. EPC 12 is also configured to control the state of battery contactor 48 and bus contactor 16 on switchboard 20.

[0037] according to Figure 1 The architecture shown depicts a system controlled by EPC 12. EPC 12 receives input from the pilot via thrust control lever 21 and pitch control lever 23. To optimize propulsion system operation, the thruster speed must remain constant regardless of thrust and pitch commands. EPC 12 receives sensor data indicating thruster speed from the speed sensor, compares the measured speed with a reference speed signal, and generates torque commands that are sent to ECU 10.

[0038] In a typical motor controller used for an EPU, multiple inverters are employed, requiring connection to a distribution board 20 inside the fuselage 102 and separate DC power lines routed through the wing 104 to the cabin interior. AC power lines 6 need to be routed from each inverter 50 to each motor star winding 26 within the cabin. All DC and AC power lines are prone to electromagnetic interference (EMI) and require EMI filters 24 and / or shielding. The distribution board is relatively complex and includes dedicated power channels for each inverter, with corresponding contactors and fuses, as well as protection coordination. Electrical integration of multiple inverters fed from the same HVDC bus 4 is challenging, requiring the development of stringent power quality and interaction requirements to limit crosstalk and circulating current between inverters. System weight is affected by additional filters and countermeasures. Furthermore, the AC motors 30 and inverters 50 have their own housings, significantly increasing weight and cost. Additionally, control functions need to communicate with multiple inverters. In the cabin, the local ECU 10 needs to multiplex information from the EPC 12 or the flight control computer 14 to the inverter controller 5.

[0039] In order to mechanically install all the above-mentioned joint components in the cabin, a mesh mechanical structure (hereinafter referred to as "space frame 60") needs to be developed to connect all the components together and to integrate the entire assembly with the aircraft main structure 106 (see Figure 1 The space frame 60 and the individual component structures need to be designed with appropriate resonance modes and damping based on the characteristics of the thrusters and fuselage. Therefore, the design process is challenging due to the individual design of each component, system modeling, and iterative convergence. Furthermore, the joint component integration method is accompanied by significant weight losses due to multiple shells and additional mesh structures.

[0040] Figure 2This is an illustration showing an overview of an integrated EPU 110 with mechanical, cooling, and electrical / control integration according to one embodiment. As used herein, the modifier “integrated” when applied to components means that these components are designed together to optimize a set of parameters. The concept presented herein involves integrating a motor 30, an inverter 50 with a corresponding hardware logic inverter controller 7 (hereinafter referred to as “hardware manager 7”), a thrust bearing / drivetrain / propeller shaft assembly 72 (hereinafter referred to as “TB / T / PS 72”), and a speed controller 64 into a single package to produce the integrated EPU 110. The aim is not to attempt to “claw” (stuff or tightly package) a system into an existing architecture, but rather to combine all drivetrain components into a single entity to optimize weight, cost, volume integration, installation, and maintenance. The integrated EPU 110 is developed as a monolithic integrated package assembly that groups all electric propulsion system functions. The resulting integrated EPU package is intended for nacelle-mounted installation for aircraft engine functions. This plug-and-play approach, integrated with the system, allows only one unit to be installed, and assembly requires only the integrated EPU 110 to be connected to the battery 18 and to the thermal management system 108. Although in Figure 2 An example of an electric propulsion drive is shown, but the concept is also applicable to electric and hybrid turbofan engines. The proposed integrated system allows for the elimination of interface components, connector systems, separate cooling circuits, and seals. The integrated system will enable a smaller, lighter package and improve efficiency and cost. It also enables key trade-offs, including integrated motor design (losses, volume) and transmission design (ratio speed), cost trade-offs (motor, transmission), and reduced system weight.

[0041] According to one embodiment, the integrated EPU 110 includes integrated motor and inverter power electronics 76 integrated within an EPU housing 112. The EPU housing 112 is further divided into an inverter power electronics compartment 114 and a motor compartment 116. An EPC 12 is embedded in the inverter power electronics compartment 114. A single DC power input line 8 feeds DC power to all inverters 50 via a common EMI filter 24 and a common low-inductance DC bus 15 (hereinafter referred to as "common DC bus 15") with interlaced conductor layers / insulation layers. Each layer of conductor in the laminated common DC bus 15 is connected to the EMI filter 24 and to the corresponding inverter in the plurality of inverters 50. The integrated EPU 110 also includes a TB / T / PS assembly 72 integrated with the EPU housing drive end plate 80. A speed controller 64 is integrated with the EPU housing rear end plate (in Figure 2 (Invisible in the middle) integration.

[0042] according to Figure 2In the illustrated embodiment, the speed governor 64 is coupled to an integrated β-bar 58, which can be axially translated to change the pitch of the propeller blades 36. Additionally, a gear-driven multi-element cooling / lubrication pump 66 and an oil cooling tank 68 are integrated in the bottom of the EPU housing 112. The pump element of the gear-driven multi-element cooling / lubrication pump 66 (see later) Figure 4 Description) directly from the main motor shaft ( Figure 2 (Not shown in the image) Gear drive. The EPU housing 112 serves as a main structural element directly connected to the aircraft main structure 106.

[0043] The high level of integration achievable by packaging all the individual modules that work together into a single system to form the integrated EPU 110 enables optimization of weight, cost, and package size. Because the functions are combined within a single housing, installation of the EPU in the cabin is significantly simpler than in a joint design. The proposed highly integrated electromechanical module provides optimal cabin integration and a superior solution while minimizing interfaces with cables and fluid piping.

[0044] The integrated EPU 110 presented in this paper provides prior art drive technology, electric motors and power electronics in a single package. Compared to the combined solution, the integrated EPU solution offers key optimizations for cabin installation and aircraft component simplification: (a) the optimized integrated EPU package design compared to individual component package designs, and integration with the space frame 60 to form an integrated mechanical mounting point 74, resulting in significant weight and cost savings; (b) direct installation of the complete EPU within the cabin compared to the fragmented approach of the prior art, resulting in significant cost savings while facilitating installation and maintenance; (c) simplification of the thermal interface with a single cooling line 82 from the integrated EPU 110 to the heat exchanger 56 (which is external to the integrated EPU 110), with no other interconnected cooling / oil lines inside the cabin; (d) simplification of the electrical wiring system by eliminating any external AC lines between the motor 30 and the inverter 50, and by providing a single DC power input line 8 to feed DC power to the interleaved inverters 50 via a common DC bus 15 within the EPU housing 112; (e) simplification / removal of the aircraft power distribution board, with no separate power distribution unit for each inverter 50; (f) simplification of the EPC... 12 is embedded within the inverter power electronics compartment 114 to provide a simple communication interface with the flight control computer 14 (by... Figure 2 (g) Simplify the control interface by providing an integrated mechanical mounting point 74 from the integrated EPU 110 to the aircraft main structure 106 for load transfer; (h) In the rotor and the inverter system surrounding the rotor ( Figure 2 Not shown in the image, but see the description below. Figures 7A to 7D(i) the opportunity to integrate combined air cooling systems between (i) and (ii) the ECU functions are performed by the EPC installed in the engine compartment, which provides superior (ii) Figure 1 Another advantage of the combined system shown is its weight and cost savings.

[0045] In combined systems, the motor, inverter, and drive are developed independently and separately. Combined systems are assembled by bolting components together, connecting them with plugs, cables and harnesses, and conduits. The component is then tested and calibrated. In contrast, the integrated system proposed in this paper optimizes the design by utilizing different synergies between the various sub-components and leveraging the innovative design freedom provided by the integrated package. For example, in the integrated package, the drive speed ratio can be customized to optimize motor size. The thrust bearing / propeller shaft assembly can also be optimized as an integrated system. Cooling can be optimized by coordinating different components. For instance, the water-cooled jacket inside the motor can be removed and replaced with oil-driven fluid cooling, allowing for a compact design by merging the housing.

[0046] As previously mentioned, typical existing electric propulsion solutions rely on the installation of numerous individual components within the naval compartment (e.g., inverters, motors, speed governors, thrust bearings / propeller shafts, controllers, and auxiliary components such as cooling pumps and cooling oil tanks). All of these components are typically interconnected to a second mesh structure (e.g., Figure 1 The space frame 60 is connected to the aircraft main structure 106. The installation of separate components multiplies the complexity of the solution, presenting significant integration challenges in terms of weight and volume within the cabin. System interconnections with wiring, cooling pipes, control harnesses, etc., are difficult to develop within the cabin and prone to failure. The mechanical / encapsulation design of the combined cabin is not optimal because each component has its own unstructured housing, and additionally, the space frame 60 is needed to provide the main load path to the aircraft main structure 106. Multiple housings are detrimental to the overall cost and weight of the combined solution. The space frame 60 needs to provide multiple attachment points and support for different components (inverters, controllers, motors, etc.), requiring complex design and reinforcement.

[0047] Figure 3This illustration shows the integration of the mechanical components of the integrated EPU 110 according to one embodiment into a single package directly connected to the aircraft main structure 106. Mechanical integration allows the EPU housing 112 to be used directly as a structural path to the aircraft main structure 106, thereby reducing overall weight compared to prior art combined solutions. Additional optimizations are made to reduce the overall mechanical weight by incorporating all housings of the individual components into an integrated package. The EPU housing 112 can be optimally designed to vibrate at its natural frequency outside of undesirable areas that might interact with system stimuli (propellers, fuselage). EPU integration, by combining all individual housings together, provides an optimal solution for system frequency design by using all available materials in a central location to create a rigid, robust monolithic package.

[0048] Figure 3 The integrated EPU 110 shown includes a TB / T / PS assembly 72 directly integrated into the motor drive side of the EPU housing 112. This integration within the EPU housing 112 eliminates the need for dedicated housings and associated support structures for thrust bearing / propeller shaft functions. The integration within the EPU housing 112 also facilitates easy lubrication through integration with the internal oil system (described in more detail below). The TB / T / PS assembly 72 includes a grounding ring (…). Figure 3 (Not shown in the diagram) to provide shaft grounding and bearing current protection. Optionally, the TB / T / PS assembly 72 may include a reducer / transmission and clutch function between the motor 30 and the thruster 32, with the motor shaft directly serving as the drive shaft, simplifying the interface with the transmission system. More specifically, the system is designed without sleeve shafts and thruster shafts for isolating the motor from thrust, bending moment, and axial misalignment, allowing the motor shaft to be directly coupled to the thruster. The thrust bearing 38 can also serve as the motor drive-side bearing, enabling the elimination of additional bearings required in typical combined solutions. The integration of the TB / T / PS assembly 72 allows for a reduction in the number of system-level bearings and interfaces, resulting in weight and cost improvements compared to prior art combined solutions.

[0049] In addition, the motor star winding 26 of the motor 30 and the inverter 50 of the motor controller (MC) are co-located in the EPU housing 112, which allows for the sharing of mechanical structure and cooling channels, and facilitates the electrical connection between the motor winding and the inverter phase pins. Figure 2 The inverter power electronics compartment 114 shown is separated from the motor 30 by a partition that allows electrical interconnection between the inverter 50 and the motor star winding 26. In an alternative embodiment (hereinafter referred to...), Figure 7A and Figure 7DIn the description, the motor controller can be configured to use a stator iron or housing as a support structure and to use stator cooling channels or jackets to surround (360 degrees) the stator 25 to provide cooling to the semiconductor power switches of the inverter 50. The co-positioning of the inverter 50 and the motor 30 also allows for the elimination of bulky additional housings and heavy-gauge AC wiring. This co-positioning also enables the integration of the cooling system between the inverter 50 and the core of the motor star windings 26 and stator 25. The motor 30 has multiple motor star windings 26 distributed at equal angular intervals in corresponding angular positions around the circumference of the stator core. The inverter modules are distributed in a similar manner, thus providing easy integration with the electrical connection and cooling of the windings.

[0050] Figure 3 The embodiment depicted also includes integrating governor functionality within an integrated EPU package. Governor 64 includes a hydraulic actuator (not shown) coupled to a mechanical system comprising an integrated β-bar 58 for controlling the thruster blade pitch. Governor 64 is mounted to the rear side of EPU housing 112. Governor 64 is supplied with hydraulic fluid directly from the EPU integrated oil system (…). Figure 3 Hydraulic pressure generated by oil 88 (not shown) provides power. An integrated β-bar 58 is disposed within a hollow motor shaft 78, which extends from the governor compartment through the inverter power electronics compartment 114 and the motor compartment 116. The integrated β-bar 58 is supported within the hollow motor shaft 78 by inserts 86a and 86b to keep the β-bar centered within the hollow motor shaft 78 without excessive vibration. Inserts 86a and 86b are attached inside the hollow motor shaft and rotate with it. However, inserts 86a and 86b are also configured to support the β-bar 58 while allowing the β-bar 58 to slide axially through openings in the inserts (e.g., through bearings). The fluid pressure of the integrated β-bar 58 is controlled by the state of a hydraulic valve in the governor 64. This pressure in the β-bar 58 moves the piston and changes the pitch of the propeller blades 36 in a known manner.

[0051] The integrated EPU concept presented in this paper simplifies the oil circuitry for lubrication and cooling by enabling sharing among different components, such as motor windings, motor bearings, inverters, thrust bearings, and governors. All oil distribution systems are located inside the EPU housing 112, except for the heat exchanger 56, which is located outside the EPU housing 112 but within the engine compartment. The gear-driven multi-element pump 66 and the oil-cooled tank 68 are integrated with the EPU housing 112, as well as the oil distribution circuit, manifold (pressure ventilation system), and channels to the different components.

[0052] Existing combined systems typically use systems with multiple pumps and tanks for cooling the motors and inverters, lubricating the thrust bearings, and supplying oil pressure to the governor, potentially resulting in four separate fluid systems. The number of fluid systems adversely affects system weight and cost by repeating numerous components. For a typical combined system, many interconnected pipes and conduits are required to distribute various fluids at different pressures to the propulsion unit components. Installing multiple dedicated pumps and tanks for each loop in the nacelle adversely affects weight, volume, and cost. Furthermore, for some components, such as the motor, internal bearings may be grease-lubricated, which negatively impacts reliability and maintainability due to the complexity involved in providing multiple loops for cooling, lubrication, and scavenging of the corresponding components.

[0053] Figure 4 This illustration shows the integration of a single fluid system for providing cooling, lubrication, and governor oil into an integrated EPU 110. The development of highly integrated electromechanical packaged solutions enables cooling synergy between different propulsion components sharing cooling at the system level using appropriate hydraulic interfaces. The integrated EPU concept allows all subsystems for cooling or lubrication to be integrated into a single fluid system. The integrated EPU 110 features an integrated oil tank 68 that receives oil returned from all the different components requiring cooling, lubrication, or oil pressure. The integrated EPU 110 also includes an integrated gear-driven multi-element pump directly coupled to the motor's spindle. Driving the pump from the motor shaft eliminates the need for a drive motor and inverter required for a combined pump. The integrated pump includes different components to provide sufficient flow and pressure to the different sub-components. The channels for oil flow are provided by… Figure 4 The arrow in the image indicates this.

[0054] like Figure 4 As shown, the components of the integrated geared multi-element pump include a high-flow, low-pressure cooling / lubrication pump 66a (hereinafter referred to as "cooling / lubrication pump 66a"); Figure 4 Also labeled "Pc", a cooling / lubricating pump 66a supplies cooling oil in series to the inverter 50, then to the motor 30, and in parallel to the thrust bearing 38 for lubrication. More specifically, the cooling / lubrication pump 66a draws oil from the integrated oil tank 68, then pumps it through the heat exchanger 56 and into the internal manifold 54d. The pressurized oil then flows in parallel through the inverter / motor cooling passage 11 and through the bearing lubrication passage 90. After cooling the motor 30, the oil returns to the integrated oil tank 68 via the internal manifold 54e and the return passage 91.

[0055] The integrated gear-driven multi-element pump also includes a scavenging pump (return oil pump) 66b (in... Figure 4Also marked "Sc", it provides pressure in the bearing scavenging passage 92 to scaveng the oil from the thrust bearing 38 and other motor bearings. The scavenged oil returns from the thrust bearing 38 to the integrated oil tank 68 via the bearing scavenging passage 92 and the scavenging pump 66b.

[0056] The integrated gear-driven multi-element pump also includes a low-flow, high-pressure governor pump 66c (hereinafter referred to as "governor pump 66c"). Figure 4 Also marked as "Pg", it provides hydraulic boost to governor 64 for actuation of blade pitch angle adjustment. Pressurized oil flows from governor pump 66c to governor 64 via governor pressurized oil passage 94; oil in governor 64 returns to integrated oil tank 68 via return oil passage 96.

[0057] Therefore, oil distribution to multiple components (motor, inverter, bearings, and governor) is completed within the integrated EPU package, eliminating the need for any external oil lines or piping. The only required hydraulic / oil connection is the external heat exchanger 56 located in the nacelle. The EPU integrated heat / oil management system enables the supply of oil for cooling or lubrication to all oil-cooled or oil-lubricated components at the appropriate flow rate and pressure using a single pump and tank system. Transfer pipes and internal channels are used where possible to eliminate piping and fittings that would otherwise increase weight and cost, and become potential sources of leakage.

[0058] Independently designed (joint) components can also have different fluid, temperature, and pressure requirements. The design integrating all components allows for compatibility. Typical joint approaches do not support sharing internal cooling between the inverter and motor windings because such cooling requires complex and cumbersome piping and conduits between the two components. It is possible to connect a complete inverter block (three inverters) in series with a complete motor housing (three motor star windings), with some external oil distribution, but the result will not be optimal thermal performance (high Δ temperature fed from the inverter to the motor windings) and hydraulic performance (high pressure drop). The co-location of the motor and inverter components allows for shared cooling between each inverter and its associated motor star winding in a series cooling configuration. The main cooling oil circuit is divided into three independent parallel paths to provide cooling for each inverter / motor star winding combination. Inverter 50 and motor star winding 26 can directly share the same cooling jacket, or the inverter cooling plate can be connected in series with the motor star winding cooling path. The proposed configuration enables an optimized cooling solution with each inverter and motor channel connected in series, while reducing the total voltage drop by connecting three independent cooling loops (loops) in parallel.

[0059] For governor pitch actuation, an additional low-flow pump element is used to boost the pressure from the main low-pressure / high-flow circuit to generate the required high pressure (with low flow) for the governor. By using a booster element connected in series with the main circuit, it is possible to have a small, optimized element for the governor circuit. For bearing scavenging, compared to scavenging the entire flow from the motor in the combined method, an additional small scavenging element is used to scaveng only the bearing elements.

[0060] Furthermore, by achieving shared cooling among the gearbox, governor, inverter, and motor, the proposed solution utilizes a single cooling system for all propulsion components, significantly simplifying the cooling system compared to existing solutions. Additionally, the integration of the gear pump and oil tank provides an optimized weight and volume solution.

[0061] In a typical EPU, different techniques can be used to cool the motor rotor depending on the detailed motor design. However, for high-power motors, a preferred design choice is not to inject oil into the air gap between the stator and rotor, as oil causes significant hydraulic / mechanical losses. In a simple design, the rotor can be cooled by a mixture of convection and conduction cooling. More advanced designs use airflow drawn in through the rotor wheel to cool the rotor magnets.

[0062] Inverter power electronics currently rely on liquid cooling systems to remove heat generated by semiconductor power switches, filters, and circuit boards. The semiconductor power switches are mounted to and in direct contact with a cooling plate through which liquid coolant flows. Cooling electronic control boards and capacitors can be challenging due to a lack of space on the cooling plate and the absence of another cooling medium to dissipate heat from these components.

[0063] Typical combined designs cannot achieve rotor air cooling in inverter designs. The inverter cooling plate's footprint must accommodate all components to allow direct contact with the cooling plate (including semiconductor power switches and DC-link capacitors). Control and drive boards typically do not contact the cooling plate and suffer from high operating temperatures due to the lack of cooling. Adding an external fan or generating heat conduction to an external structure with housing heat sinks will significantly impact inverter design by increasing weight and cost.

[0064] Figure 5This is an illustration of integrated air cooling for the motor 30 and inverter 50, with integrated EPU 110. The cooling airflow through the integrated EPU 110 is indicated by an arrow pointing to the left. The integrated EPU 110 is designed to allow air cooling of the motor rotor to be directed through the inverter power electronics compartment 114 to provide cooling to components that are not in direct contact with the cooling plates. The motor rotor wheel is designed to have impeller capability to draw cooling air 62a through the rotor center. The motor front plate has a grille with air inlets to allow airflow through the rotor inner wheel. The rotor wheel may include heat sinks on the back of the rotor magnets to guide air at an appropriate speed and to bring the airflow close to the magnets. The cooling air 62a drawn into the rotor wheel is used to remove heat from the magnets and limit their operating temperature.

[0065] Once the cooling air 62b leaves the motor, a portion of it can be directed directly into the inverter power electronics compartment 114 to cool components such as drive boards, control boards, and, where possible, filter components such as capacitors and inductors. The use of forced air cooling allows for efficient, lightweight cooling of all electronic components that do not come into contact with the cooling plates. Alternatively, air can be directed to cooling fins integrated into the inverter power electronics compartment 114 to increase convective cooling provided through this interface. Cooling air 62c leaving the inverter 50 cools the common EMI filter 24, while cooling air 62d leaving the inverter 50 cools the EPC 12.

[0066] The advantage of providing forced air cooling to power electronic components is that the inverter can have a compact design, with liquid cooling for the semiconductor power modules and air cooling for the DC-link capacitors and controller / drive board components. Air can be blown directly onto those components or onto the heat sink structure (cooling plate or housing) that is in thermal contact with them. The proposed compact design also allows for a reduction in the inverter's cooling plate footprint. Therefore, the integrated EPU 110 presented in this paper provides significant design optimization by enabling the inverter and motor to share both liquid and air cooling systems.

[0067] In addition, integrating all inverters 50 into a single package enables multiple electrical collaborations to optimize power electronics design and motor windings. Figure 6This is an illustration of the integration of electrical and control components of an integrated EPU 110 according to one embodiment. EPU inverter integration allows for a single DC terminal and DC power input line 8 for the EPU within a single wiring harness between the integrated EPU 2 and battery 18. By using a single DC dual (positive / negative) wiring harness instead of three DC dual wiring harnesses, aircraft wiring between battery 18 and EPU 2 is simplified. Furthermore, the number of additional connectors on the EPU and battery is reduced. Therefore, the integrated solution simplifies DC power distribution and wiring by using a single input and a common DC bus 15 within the EPU housing 112. Typically, shielded aircraft wiring is required for safety and EMI purposes. Using a single wiring harness makes shielding significantly easier than using multiple harnesses. Simplified wiring and avoidance of additional connectors enable simple integration within the aircraft, resulting in savings in weight, volume, and cost. The integrated method also avoids the use of a dedicated inverter power distribution and allows power to be fed directly from battery 18 to the common bus within the EPU housing 112.

[0068] Furthermore, the co-location of the inverter and motor avoids the need for large-gauge AC connection wires. In a typical co-location solution, for each inverter 50, three single-phase conductors must be wired between the inverter and the motor for each motor star winding 26. For high-power drive motors, each inverter typically has multiple motor star windings to achieve the required rated power. This requires a large number of large-gauge wires (9 to 18) to interconnect the inverter 50 and the motor star windings 26. Wiring those wires is complex and expensive, and can significantly impact weight and volume. Figure 5 The integrated EPU 110 shown eliminates the need for all AC wiring, and the connection between the motor star winding and the inverter phase pins is accomplished directly through the small busbar 57 in the integrated package.

[0069] Furthermore, in typical integrated solutions, AC lines are a significant contributor to EMI disturbances and motor winding overvoltage stress. AC lines typically need to be quite short to limit motor winding overvoltage stress and require complete shielding to mitigate EMI disturbances from surrounding equipment. Since the connection is the shortest possible, thus limiting winding overvoltage, and EMI shielding is provided by the EPU housing 112, the integrated solution presented in this paper offers an excellent solution to both of these problems. Additionally, since AC parasitic capacitance is virtually zero and does not limit inverter switching, this type of integration allows for an increase in the inverter's switching frequency. Increasing the switching frequency reduces motor rotor losses and optimizes the motor's magnetic design.

[0070] Furthermore, the integrated package proposed in this paper enables the use of interleaved and lumped filtering to optimize EMI filtering (see [link]). Figure 6The common EMI filter 24 is used in the inverter 50. All inverters 50 are connected to the common DC bus 15 and share a common single DC link capacitor. Figure 6 (Not shown in the diagram). By using a centralized DC link capacitor shared among the three inverters, the size of the DC link capacitors required for the total number of inverters can be reduced compared to the total size of the three DC link capacitors used for three individual inverters. All inverters 50 are directly connected to the common DC link capacitor using a common DC bus 15. According to one proposed implementation, the common DC bus 15 is a low-inductance laminated bus with interleaved (alternating) layers of conductors and insulation, and the switching modes of the inverters 50 allow the AC power signals to be interleaved in phase. This technique allows for reduction of disturbances generated by the three interleaved inverters, which in turn allows for a reduction in the capacitance of the DC link capacitors compared to the joint method. In a typical joint method, the input filter for each inverter includes a differential inductor to limit potential circulating currents between inverters. The integrated method proposed in this paper eliminates the separate input filter inductor in each inverter, thereby saving weight / volume and providing improved efficiency. In contrast, the typical joint method does not allow for this optimization because the inverters 50 are independent of each other and it is not possible to interleave the switching modes. Additionally, for combined inverters, since the switching modes are random among themselves, a DC input filter inductor is required to limit the recirculation current.

[0071] The inverter's DC input is the primary interface to the rest of the electrical system. The longest feeder in the system is the DC power input line 8 from battery 18 to inverter 50. Controlling EMI radiation generated through this interface is important. With a combined approach, each inverter requires a dedicated filter, sized to suit the corresponding switching mode of a single inverter. The integration method proposed in this paper allows a common EMI filter 24 to be incorporated into a common-mode / differential-mode configuration for the group of inverters 50. The size of the common EMI filter 24 is set as a function of the interleaved inverter switching modes, thereby enabling a reduction in the weight and size of the integrated EPU 110.

[0072] In the integrated approach proposed in this paper, all inverters 50 are fed by a single DC power input line 8 via a common DC bus 15. In the event of an inverter failure, the faulty inverter can be isolated using an active short-circuit (ASC) method (where the power switch of the faulty inverter is closed), thus isolating other inverters (i.e., other motor controller channels) in the event of a failure in one inverter. The integrated solution proposed in this paper enables the use of ASC on each motor star winding to manage inverter failures; it eliminates the need to disconnect contactors or blow fuses on each inverter. The integrated solution makes it possible to achieve a fault-tolerant design with minimal power distribution.

[0073] According to one implementation, the embedded EPC 12 is a controller configured with corresponding software modules that perform the following functions: (a) motor speed loop; (b) pitch control loop; (c) motor current loop; (d) interleaving of power signals output by inverter 50; and (e) mode control.

[0074] In summary, the integrated solution proposed in this paper provides electrical synergy by combining a common DC link capacitor, a single DC terminal, simplified DC power distribution, simplified wiring, and integrated speed / position sensor control.

[0075] Figures 7A to 7D This is a diagram illustrating an example implementation of a motor / inverter cooling integration and a speed controller / pump solution.

[0076] Figure 7A An integrated EPU 110 is depicted, wherein the motor shaft 33 is rotatably mounted within the EPU housing 112 (in Figure 7A (Only partially shown). The motor shaft 33 is supported by a motor shaft bearing 35. The rotor core 39 of the rotor 28 is mounted on the hollow motor shaft 33, with a plurality of permanent magnets 37 arranged around its periphery. The rotor 28 is surrounded by a stator 25 comprising a stator core 27 and stator windings 29. The stator 25 is further surrounded by channels through which liquid coolant 19 flows (in... Figure 7A A cooling jacket 41 surrounds the stator 25 from right to left (as indicated by the arrow pointing to the left). The cooling jacket 41 is mounted to the back iron of the stator 25. (The back iron is the radially outer housing of the stator core.) Multiple power modules 31 are mounted on the outer surface of the cooling jacket 41, each power module including a corresponding inverter and inverter controller. The cooling jacket 41 is configured such that liquid coolant 19 flowing through the channels of the cooling jacket 41 cools both the stator 25 and the power modules 31.

[0077] Still referencing Figure 7A The EPU 110 also includes a main drive gear 49 mounted to the front end of the motor shaft 33. The teeth of the main drive gear 49 mesh with the teeth of the pump drive gear 47 and the thruster shaft drive gear 55, both of which are offset from the central axis of the motor shaft 33. A pump 98, which pumps liquid coolant through a cooling jacket 41, has an input shaft attached to and driven by the pump drive gear 47. The thruster shaft drive gear 55 is mounted to a hollow thruster shaft 34 offset from the motor shaft 33. The thruster shaft 34 is supported by a thrust bearing 38. The gear set is adapted to reduce the rotational speed of the thruster shaft 34 relative to the rotational speed of the motor shaft 33, which is part of a transmission subassembly. A speed controller 64 is located behind the offset thruster shaft drive gear 55 and controls the axial displacement of a β-rod 58 within the hollow thruster shaft 34 to change the thruster blades ( Figure 7A The pitch (not shown in the diagram).

[0078] Figure 7B An EPU 110 according to an alternative embodiment is depicted, in which a combination of jacket / back iron cooling and a flooded stator solution is used to cool the stator 25. More specifically, the outlet of the cooling jacket 41 is in fluid communication with an internal stator cooling channel 3 having an outlet 3a. In the case of the flooded stator, the stator windings 29 are immersed in the cooling fluid to provide direct and effective cooling. The stator 25 has a stator housing 43 (also called a back iron) that defines the internal stator cooling channel 3, which allows the cooling fluid to circulate directly through the winding slots formed in the stator core 27. Figure 7A In a similar configuration as shown, the power module 31 is directly mounted in the cooling jacket 41. Figure 7B The example implementation depicted uses a planetary gearbox 53 to allow the hollow motor shaft 78 to rotate faster than the propeller shaft 34, wherein the speed regulator 64 is mounted to the rear of the EPU housing 112 and the β rod 58 extends the length of the EPU 110. Additionally, the pump 98 is connected to planetary gears within the planetary gearbox 53.

[0079] Figure 7C The motor structure shown is similar to Figure 7B The motor configuration shown differs from the pump 98, which uses a gear set to connect the motor 30 to the hollow motor shaft 78 via gears. The motor drive element is configured for direct drive without a reducer. Optionally, a mechanical coupling 59 may be incorporated.

[0080] Figure 7D An EPU 110 according to another embodiment is depicted, wherein the stator 25 is cooled using overflow stator cooling. For example... Figure 7B As in the illustrated embodiment, the internal stator cooling channels 3 are partially formed by the stator housing 43. Each internal stator cooling channel 3 has an inlet 3b and an outlet 3a. In the case of an overflow stator, the stator windings 29 are immersed in the cooling fluid to provide direct and effective cooling to the motor. The power modules 31 are located near the motor end winding compartment at the rear of the motor. For each power module 31, a liquid coolant (e.g., oil) flows over a corresponding cooling plate 1 to cool inverter components (power switches, capacitors, etc.). The oil first flows over the cooling plate 1 and is then guided through slots in the stator core 27 ( Figure 7D (Not shown in the image). In this way, an inverter and its associated motor star winding are arranged in series to receive liquid coolant. In this way, the individual inverter / motor star winding pairs are arranged in parallel, such that the cooling flow is separated.

[0081] for Figures 7A to 7DIn all the configurations shown, the thrust bearing 38 is cooled in parallel with the main cooling channel, and scavenging air is supplied by an additional integrated pump element ( Figures 7A to 7D (Not shown in the image) is provided. Governor oil pressure is supplied from the mains via a booster integrated pump element. For simplicity, Figures 7A to 7D The oil tank is not depicted, but it is integrated within the EPU package. The speed controller is shown as being located behind the motor, but it can also be located in the front, and different types of speed controllers are available, such as counterweight type.

[0082] To improve the availability of electric propulsion systems, existing architectures rely on using two redundant, separate electric propulsion channels (A / B) to drive the thruster 32. A major drawback is the duplication of many components, such as housings, mechanical structures, cooling systems (pumps, tanks, etc.), bearings, shafts, and controllers. Furthermore, coordination between the two different channels can be difficult to achieve, and integration with components such as the governor 64 is challenging. This component duplication increases the weight and size of the redundant electric propulsion system.

[0083] Conversely, the integrated EPU enables the development of optimized, redundant electric propulsion architectures. The dual-channel integrated EPU package allows for the reconfiguration of two separate electric propulsion channels. Figure 8A This is an illustration showing an overview of an integrated EPU 110 with multi-channel integration according to one embodiment. Motor controller channel A includes three inverters 50a that receive DC power from battery 18a via a series-connected battery contactor 48a, DC power input line 8a, EMI filter 24a, and low-inductance bus 15a. Battery 18a is managed by battery management system 22a. Similarly, motor controller channel B includes three inverters 50b that receive DC power from battery 18b via a series-connected battery contactor 48b, DC power input line 8b, EMI filter 24b, and low-inductance bus 15b. Battery 18b is managed by battery management system 22b.

[0084] for Figure 8A The integrated EPU 110 shown can use the same pump and tank circuit to cooperate with the cooling system between the two channels. The mechanical structure and housing can be integrated into a single package to minimize weight and volume. Similar to the single-channel package, the electrical interconnection between the motor 30 and the inverter 50 is done directly via a small bus 57 to eliminate large AC lines. The EPU housing 112 is directly connected to the aircraft main structure 106 via integrated mechanical mounting points 74 to react to propeller loads and torque. The governor 64 and transmission ( Figure 8A (Not shown) are integrated in the rear and front of the package, respectively. Two separate power electronics compartments are created for motor controller channel A and motor controller channel B.

[0085] Figure 8B It shows the use of Figure 8A This diagram illustrates an integrated multiphase fault-tolerant motor design for an electric propulsion unit. Motor channels A and B can be implemented using an integrated multiphase fault-tolerant motor design. The motor is designed so that each motor star winding is magnetically and electrically isolated from each other (more specifically, the motor star winding 26a of motor channel A is isolated from the motor star winding 26b of motor channel B). Minimal magnetic and electrical connections between the motor star windings of motor channels A and B can be achieved using special winding strategies (e.g., concentrated windings), winding placement (stator position), and motor pitch and slot design. Additionally, the motor star winding 26a of motor channel A and the motor star winding 26b of motor channel B are thermally isolated due to the stator layout. The integrated motor in this example embodiment will have three motor star windings 26a for motor channel A and three motor star windings 26b for motor channel B. The proposed design will implement a common stator core 27 for motor channels A and B. It will also allow rotor components (shaft, magnet, bearing, etc.) to be shared between motor channel A and motor channel B.

[0086] In the event of a fault in the motor star winding in motor channel A (or B), an active short-circuit (ASC) strategy is used to short-circuit the affected star winding A (or B) by closing the power switch in the inverter of the associated motor controller channel A (or B). The stator slot and winding configuration are sized to achieve an impedance of ~1PU to limit the short-circuit current to the maximum rated current. Under these conditions, during ASC, the losses in the faulty motor star winding will equal the rated losses. At rated speed, the motor star winding connected to the short-circuited power switch produces minimal drag torque, and the normal motor star winding will be able to maintain the drive propeller.

[0087] In the event of a fault in motor channel A (or B), all inverters in the associated motor channel A will be commanded to shut down one or two rows of power switches (3 or 6 switches) to effectively short-circuit the star windings of all motors in the faulty motor channel. In this case, motor channel A will not feed energy to the short circuit in the inverter. At rated speed, the short-circuited star windings of all motors in motor channel A (or B) will produce minimal drag torque, and motor channel B (or A) will be able to maintain drive propellers.

[0088] The aforementioned integrated multiphase fault-tolerant motor design enables the implementation of two independent motor functions without duplicating considerably large components such as stator cores, rotor magnets, shafts, bearings, housings, and support structures. The proposed solution optimizes weight and cost. Redundant motor functions are achieved without the need for a mechanical clutch or disengagement.

[0089] To limit control complexity, a single EPC can be used for two motor controller channels A / B to command different inverters and coordinate control between the two motor channels A / B. EPC can be used with... Figure 6 The single package structure shown is similar to that used for integrating power electronics into a compartment.

[0090] Figure 9A This is an illustration showing an overview of a dual-motor EPU 110' with integrated drivetrain according to another embodiment. The dual-motor EPU 110' includes a first motor 30a disposed in the front of an EPU housing 112 and a second motor 30b disposed in the rear of the EPU housing 112. The first motor 30a includes a hollow motor shaft 78a, a rotor core 39a mounted to and surrounding the hollow motor shaft 78a, and a stator core 27a surrounding the rotor core 39a. The second motor 30b includes a hollow motor shaft 78b, a rotor core 39b mounted to and surrounding the hollow motor shaft 78b, and a stator core 27b surrounding the rotor core 39b. Both motors are axially arranged in a straight line. The solution shown integrates power electronics with each motor to actively share cooling between the power module 31 and the stator cores 27a and 27b.

[0091] Hollow motor shafts 78a and 78b are selectively connected sequentially to corresponding portions of the hollow main drive shaft 17 and surround those portions. β-rod 58 is axially translatable within the hollow main drive shaft 17. Hollow motor shafts 78a and 78b are connected to the hollow main drive shaft 17 using sets of corresponding mechanical coupling devices 13, one set of which... Figure 9B The middle part is shown. The mechanical coupling device 13 can be of the type of overrunning clutch, synchronous self-shifting clutch or wedge clutch. Figure 9B The triangle in the diagram represents the spline interface between the mechanical coupling 13 and the hollow main drive shaft 17. Each motor 30a and 30b includes a corresponding set of motor shaft bearings 35 mounted to the EPU housing 112 to independently support rotors 28a and 28b. Therefore, when both hollow motor shafts 78a and 78b are connected to the hollow main drive shaft 17, the two motors 30a and 30b drive the rotation of the hollow main drive shaft 17.

[0092] In an alternative scenario, if the hollow motor shaft 78a disengages from the hollow main drive shaft 17 while the hollow motor shaft 78b remains connected, only motor 30b drives the rotation of the hollow main drive shaft 17. Conversely, if the hollow motor shaft 78b disengages from the hollow main drive shaft 17 while the hollow motor shaft 78a remains connected, only motor 30a drives the rotation of the hollow main drive shaft 17. Therefore, if a motor has failed, its mechanical coupling 13 will disengage the rotor of the failed motor. The rotor of the failed motor will stop, and the associated stator windings will be de-energized. The normal motor can continue to operate and rotate without any effect from the failed motor. The use of mechanical disconnection allows for the independent disengagement of either motor in the event of a failure or abnormal operation. Figure 8A A significant difference in the proposed solution is that the faulty motor rotor is brought to a standstill and does not generate back electromotive force. Due to this characteristic, the faulty motor and electronics do not need to continuously carry short-circuit current. When a fault is detected in a motor, the associated inverter is commanded to initiate ASC mode. Automatically responding to this ASC mode, the rotor begins to decelerate and mechanically disengage. During ASC, torque increases as the motor speed decreases. Once the rotor reaches zero speed, the ASC state is maintained until the rotor reaches zero speed. The normal motor continues to rotate and drives the actuator independently of the faulty motor. The motor and inverter will need to maintain a short circuit during the deceleration phase (a few seconds) of the faulty motor rotor. This allows for a reduction in the weight and size of the motor's magnetic / electrical components, as well as the size of the power switch.

[0093] Therefore, the primary compromise is to use a mechanical disconnect device instead of a high-impedance motor design. However, a hybrid solution can combine these two approaches. In the event of a fault in a single star winding of motor 30a, the faulty star winding will be placed in ASC mode. The two remaining star windings of motor 30a will remain operational and driven. Motor 30b will also remain operational. If two or more star windings fail or a distributed short circuit occurs in motor 30a, motor 30a will disconnect (all star windings will be in ASC mode) and motor 30b will remain operational. The hybrid approach can also provide redundancy for motor disconnect functionality for safety purposes.

[0094] Mechanical coupling device 13 (which can be selectively actuated to perform a disconnection function) can be tightly integrated with motor shaft bearing 35 (e.g. Figure 9C(As shown), to minimize the weight and size impact of adding a disconnect device to each motor. More specifically, the inner wall of the bearing and the outer wall of the clutch can be the same component, resulting in a reduced number of components, reduced complexity, and fewer failure modes. The mechanical coupling device 13 can also be used to disconnect both motors 30a and 30b from the main drive shaft 17 simultaneously in the event of a fault such as overspeed or a mechanical fault such as bearing failure or rotor bottom-down failure.

[0095] The solution presented in this paper is easily scalable, in which multiple motor inverter modules can be stacked via mechanical coupling to the main drive shaft 17. An example with two motors can be easily expanded to three or more motors. Depending on the chosen safety and isolation method, each motor can be designed with minimal impedance or ~1PU. Alternatively, if mechanical disconnection is not required, multiple motors, each with ~1PU impedance, can be stacked with direct coupling (without mechanical coupling).

[0096] The flowcharts and block diagrams in the various depicted embodiments illustrate the architecture, functionality, and operation of some possible implementations of the devices and methods in the illustrative embodiments. In this regard, each block in a flowchart or block diagram may represent a module, segment, function, and / or part of an operation or step. For example, one or more blocks may be implemented as program code, hardware, or a combination of program code and hardware. When implemented in hardware, the hardware may, for example, take the form of an integrated circuit manufactured or configured to perform one or more operations in the flowchart or block diagram.

[0097] The embodiments disclosed above use one or more controllers. Such devices typically include processors or computers, such as central processing units, microprocessors, reduced instruction set computer processors, application-specific integrated circuits (ASICs), programmable logic circuits, field-programmable gate arrays (FPGAs), digital signal processors, and / or any other circuitry or processing means capable of performing the functions described herein. The methods described herein can be encoded as executable instructions embodied in a non-transitory tangible computer-readable storage medium, including but not limited to storage devices and / or memory devices. When executed by a controller, such instructions cause the controller to perform at least a portion of the methods described herein.

[0098] The methods described herein can be encoded as executable instructions embodied in a non-transitory tangible computer-readable storage medium, including but not limited to storage devices and / or memory devices. When executed by a processing or computing system, such instructions cause the system device to perform at least a portion of the methods described herein.

[0099] While an integrated electric propulsion unit for aircraft has been described with reference to various embodiments, those skilled in the art will understand that various changes can be made and its components can be replaced with equivalents without departing from the scope of the teachings herein. Furthermore, many modifications can be made to adapt the teachings herein to specific situations without departing from the scope of the invention. Therefore, the claims are not intended to limit the specific embodiments disclosed herein.

[0100] Note: The following paragraphs describe other aspects of this disclosure:

[0101] A1. An electric propulsion unit, comprising:

[0102] case;

[0103] An AC motor is housed within a housing and includes multiple bearings supported within the housing, a motor shaft rotatably connected to the housing via the multiple bearings, a stator supported by the housing, and a rotor mounted to the motor shaft.

[0104] An inverter, housed within a casing, is connected to receive direct current (DC) power and convert it into alternating current (AC).

[0105] The controller, housed within the housing, is configured to control the operation of the inverter; and

[0106] A cooling circuit, configured to guide the flow of circulating liquid, wherein the cooling circuit includes:

[0107] The fuel tank is installed onto the casing;

[0108] A cooling pump, mounted to the housing, connected to the motor shaft by gears, and in fluid communication with the oil tank; and

[0109] Cooling channels are located inside the housing and connected to guide circulating liquid from the cooling pump toward the oil tank along the flow path.

[0110] A2. The electric propulsion unit according to paragraph A1, wherein the cooling channel has a first channel portion passing through the inverter and a second channel portion passing through the stator and in fluid communication with the first channel portion.

[0111] A3. The electric propulsion unit according to paragraph A1 further includes:

[0112] Thrust bearing / transmission / propeller shaft assembly, including thrust bearing, transmission, and propeller shaft; and

[0113] The propeller is mounted to the propeller shaft and includes propeller blades with an adjustable pitch angle.

[0114] A4. The electric propulsion unit as described in paragraph A3, wherein the cooling circuit further includes:

[0115] A heat exchanger, located outside the housing and in fluid communication with the cooling pump;

[0116] Manifold, disposed within the housing and in fluid communication with the heat exchanger; and

[0117] The bearing lubrication channel is in fluid communication with the manifold and the thrust bearing.

[0118] A5. The electric propulsion unit according to claim A4, wherein the cooling circuit further comprises:

[0119] The bearing scavenging pump is in fluid communication with the oil tank; and

[0120] The bearing scavenging air passage is in fluid communication with the thrust bearing and the bearing scavenging air pump.

[0121] A6. The electric propulsion unit according to paragraph A4 further includes a speed governor configured to adjust the pitch angle of the propeller blades, wherein the cooling circuit further includes:

[0122] The governor pump is in fluid communication with the manifold.

[0123] The governor pressurization oil passage is in fluid communication with the governor pump and the governor; and

[0124] The oil return channel is in fluid communication with the governor and the oil tank.

[0125] A7. An electric propulsion unit, comprising:

[0126] case;

[0127] An AC motor is housed within a housing and includes multiple bearings supported within the housing, a motor shaft rotatably connected to the housing via the multiple bearings and having a rotation axis, a stator supported by the housing, and a rotor mounted to the motor shaft.

[0128] The main drive gear is mounted to the front end of the motor shaft and has teeth;

[0129] The propeller includes a hollow propeller shaft with a rotation axis and propeller blades with an adjustable pitch angle, the rotation axis being offset from the rotation axis of the motor shaft;

[0130] The β rod can translate axially within the hollow thruster shaft;

[0131] The speed governor is configured to adjust the pitch angle of the propeller blades by actuating the axial translation of the β rod;

[0132] The thruster shaft drive gear is mounted on the hollow thruster shaft and has teeth that mesh with the teeth of the main drive gear;

[0133] Multiple power modules are arranged radially outward from the stator; and

[0134] The controller, housed within the housing and configured to perform operations including:

[0135] Controlling the operation of these multiple power modules; and

[0136] Control the pitch angle of the propeller blades.

[0137] A8. The electric propulsion unit according to paragraph A7 further includes a cooling jacket disposed between the stator and the power module.

[0138] A9. An electric propulsion unit, comprising:

[0139] case;

[0140] Multiple first bearings and multiple second bearings are supported within the housing;

[0141] The main drive shaft is supported by multiple first bearings and multiple second bearings within the housing;

[0142] The first hollow motor shaft and the second hollow motor shaft, and the corresponding sections surrounding the main drive system shaft;

[0143] The first pair of mechanical coupling devices and the second pair of mechanical coupling devices selectively connect the first hollow motor shaft and the second hollow motor shaft to the main drive shaft, respectively;

[0144] The first rotor and the second rotor are respectively mounted on the first hollow motor shaft and the second hollow motor shaft;

[0145] The first stator and the second stator are supported within the housing and are respectively disposed radially outside the first rotor and the second rotor; and

[0146] The propeller is mechanically connected to the main drive shaft; and

[0147] The controller, housed within the housing, is configured to selectively activate a pair of mechanical couplings to disengage a hollow motor shaft from the main drive shaft.

Claims

1. An electric propulsion unit, wherein, The electric propulsion unit includes: case; An AC motor is disposed within the housing, and the AC motor includes a plurality of bearings supported within the housing, a hollow motor shaft rotatably connected to the housing via the plurality of bearings, a stator supported by the housing, and a rotor mounted to the hollow motor shaft; β rod, which can be axially translated inside the hollow motor shaft; A thruster mechanically coupled to the hollow motor shaft, the thruster including thruster blades having an adjustable pitch angle depending on the axial position of the β rod; A speed controller configured to adjust the pitch angle of the propeller blades by actuating the axial translation of the β rod; An inverter, which is disposed within the housing and is connected to receive DC power for converting it into AC power; A first cooling channel thermally connected to the inverter and a second cooling channel thermally connected to the stator, the second cooling channel being in fluid communication with the first cooling channel; and A controller, disposed within the housing, and configured to perform operations including: Controlling the operation of the inverter; and Control the pitch angle of the propeller blades.

2. The electric propulsion unit according to claim 1, further comprising one or more inserts attached inside the hollow motor shaft, the one or more inserts being configured to support the β rod while allowing the β rod to slide axially.

3. The electric propulsion unit according to claim 1 further includes a thrust bearing / transmission device / propeller shaft assembly integrated with the drive end plate of the housing.

4. The electric propulsion unit according to claim 1, wherein, The speed regulator is integrated with the rear end plate of the housing.

5. The electric propulsion unit according to claim 1, wherein, The first cooling channel is a cooling plate.

6. The electric propulsion unit according to claim 1, wherein, The stator includes a stator housing, and the second cooling channel is partially defined by the stator housing.

7. The electric propulsion unit according to claim 1, wherein, The stator includes a stator housing, and the inverter is arranged radially outward from the stator housing. The electric propulsion unit also includes a cooling jacket disposed between the inverter and the stator housing.

8. An electric propulsion system, wherein, The electric propulsion system includes a first battery configured to generate DC power, a first DC power input line connected to the first battery, and an electric propulsion unit connected to the first DC power input line, wherein the electric propulsion unit includes: case; An AC motor is disposed within the housing, and the AC motor includes a plurality of bearings supported within the housing, a motor shaft rotatably connected to the housing via the plurality of bearings, a stator supported by the housing, and a rotor mounted to the motor shaft; A first electromagnetic interference filter is disposed within the housing and is connected to receive DC power from the first battery via the first DC power input line. A first DC bus is disposed inside the housing and is connected to the first electromagnetic interference filter. A plurality of first inverters are disposed within the housing, and each of the plurality of first inverters is connected to the first DC bus; A first cooling channel thermally connected to the inverter and a second cooling channel thermally connected to the stator, the second cooling channel being in fluid communication with the first cooling channel; and A controller is disposed within the housing and configured to control the operation of the plurality of first inverters.

9. The electric propulsion system according to claim 8, wherein, The first DC bus includes interleaved conductor layers and insulating layers, each conductor layer being connected to the first electromagnetic interference filter and to a corresponding inverter among the plurality of inverters.

10. The electric propulsion system according to claim 8, wherein, The stator includes multiple motor star windings, and the electric propulsion system also includes multiple AC buses that connect the inverter to the corresponding motor star windings.

11. The electric propulsion system of claim 8, further comprising a second battery configured to generate DC power and a second DC power input line connected to the second battery, wherein, The electric propulsion unit also includes: A second electromagnetic interference filter is disposed within the housing and is connected to receive DC power from the second battery via the second DC power input line; A second DC bus, disposed within the housing, and connected to the second electromagnetic interference filter; and A plurality of second inverters are disposed within the housing, and each of the plurality of second inverters is connected to the second DC bus. The controller is also configured to control the operation of the plurality of second inverters.

12. The electric propulsion system of claim 8 further includes a thruster mechanically coupled to the motor shaft.

13. An electric propulsion unit, wherein, The electric propulsion unit includes: case; An AC motor is disposed within the housing, and the AC motor includes a plurality of bearings supported within the housing, a motor shaft rotatably connected to the housing via the plurality of bearings and having a rotation axis, a stator supported by the housing, and a rotor mounted to the motor shaft; A main drive gear, which is mounted to the front end of the motor shaft and has teeth; A propeller comprising a hollow propeller shaft having a rotation axis and propeller blades having an adjustable pitch angle, the rotation axis being offset from the rotation axis of the motor shaft; β rod, which is capable of axial translation within the hollow thruster shaft; A speed controller configured to adjust the pitch angle of the propeller blades by actuating the axial translation of the β rod; A thruster shaft drive gear is mounted to the hollow thruster shaft and has teeth that mesh with the teeth of the main drive gear. Multiple power modules are arranged radially outward from the stator; A first cooling channel thermally connected to the AC motor and a second cooling channel thermally connected to the stator, the second cooling channel being in fluid communication with the first cooling channel; and A controller, disposed within the housing, and configured to perform operations including: Controlling the operation of the plurality of power modules; and Control the pitch angle of the propeller blades.

14. The electric propulsion unit according to claim 13 further includes a cooling jacket disposed between the stator and the power module.

15. An electric propulsion unit, wherein, The electric propulsion unit includes: case; A plurality of first bearings and a plurality of second bearings, the plurality of first bearings and the plurality of second bearings being supported within the housing; The main drive shaft is supported by the plurality of first bearings and the plurality of second bearings supported within the housing. A first hollow motor shaft and a second hollow motor shaft, the first hollow motor shaft and the second hollow motor shaft surrounding corresponding segments of the main drive system shaft; The first pair of mechanical coupling devices and the second pair of mechanical coupling devices selectively connect the first hollow motor shaft and the second hollow motor shaft to the main drive shaft, respectively. A first rotor and a second rotor, the first rotor and the second rotor being respectively mounted on the first hollow motor shaft and the second hollow motor shaft; A first stator and a second stator, the first stator and the second stator being supported within the housing, and the first stator and the second stator being respectively disposed radially outside the first rotor and the second rotor; and A thruster, the thruster being mechanically connected to the main drivetrain shaft; A first cooling channel thermally connected to the motor and a second cooling channel thermally connected to the stator, the second cooling channel being in fluid communication with the first cooling channel; and A controller, disposed within the housing, is configured to selectively activate a pair of mechanical couplings to disengage a hollow motor shaft from the main drive shaft.

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