A stator double-winding structure axial flux motor

Abstract

The application discloses a kind of stator double-winding structure axial flux motor, the motor includes the alternately stacked multiple stators and rotors along the axial direction, and the rotor adopts Halbach array.The core is that each stator is provided with the first winding combination and the second winding combination independent of parameter;All first winding combinations are connected in series to form low-speed coil, and all second winding combinations are connected in parallel to form high-speed coil;Respectively by first controller and second controller, independent driving is carried out by semiconductor relay;Control unit controls semiconductor relay according to working condition demand, realizes the non-contact switching between two sets of windings.The application is decoupled by electromagnetic parameter design, so that low-speed coil is optimized to large torque output, high-speed coil is optimized to high efficiency weak magnetic speed expansion, combined with solid-state electronic switching technology, single motor is realized in wide speed range High performance, undisturbed operation and high reliability redundancy in wide speed range, especially suitable for electric vertical take-off and landing aircraft and supercar and other high-end equipment.

Description

Technical Field

[0001] This invention relates to the field of motor technology, specifically to an axial flux motor with a stator double winding structure. Background Technology

[0002] With the rapid development of high-end electric transportation equipment such as electric vertical takeoff and landing (eVTOL) aircraft and supercars, the performance requirements for drive motors are becoming increasingly stringent and multi-dimensional. Specifically, an ideal drive motor must simultaneously meet the following core requirements:

[0003] Low-speed high-torque output capability: In eVTOL vertical take-off and landing, supercar rapid acceleration and start-up, etc., the motor needs to be able to output a large instantaneous torque in the low speed range, and it is required to maintain a high energy conversion efficiency in this process to avoid excessive energy waste during the "powerful stomp" process.

[0004] High-speed and high-efficiency cruise capability: When eVTOL is cruising at level speed or when a supercar is traveling at high speed, the motor needs to operate in a high speed range and maintain extremely high operating efficiency (e.g., above 96%) within this range to maximize the driving range or mileage. At the same time, there are high requirements for the maximum speed to meet the cruising speed requirements.

[0005] Smoothness and speed of operating mode switching: The motor must be able to switch quickly and smoothly between low-speed, high-torque mode and high-speed, high-efficiency mode. During the switching process, the output torque should not be significantly interrupted or fluctuate drastically (e.g., torque fluctuation should be less than 5%) to avoid eVTOL instability or jerking sensation in passenger vehicles.

[0006] High reliability and fault tolerance: Given the extreme safety requirements of aviation and high-performance vehicle applications, the drive system must have inherent redundancy. Even in the event of a failure in the motor windings or controller, the system should not completely lose power but should be able to continue operating in derating mode to ensure a safe landing or journey to a repair point.

[0007] However, existing motor solutions cannot simultaneously meet the aforementioned mutually restrictive performance requirements:

[0008] For traditional single-winding motors, the winding parameters (such as number of turns, wire diameter, and connection method) are fixed during the design phase, making it impossible to adapt to the vastly different operating conditions at high and low speeds. Specifically, the problems are as follows: in the low-speed range, a large current is usually required to output high torque, leading to a significant increase in copper losses (I²R losses) and serious energy waste; in the high-speed range, the fixed winding inductance limits the motor's "field weakening" speed-enhancing capability, resulting in a narrow constant-power speed regulation range, which cannot meet the high cruising speed requirements of eVTOL and supercars; furthermore, the single-winding structure lacks redundancy, and a winding or controller failure will cause the motor to completely stop, failing to meet the safety standards of high-end applications.

[0009] For dual-winding motors that use mechanical contact switches (such as contactors and relays) for winding switching, although different parameters for low-speed and high-speed windings can balance high and low-speed performance to some extent, the mechanical switches themselves introduce new bottlenecks. At high power levels, the mechanical contacts are prone to arcing during switching, leading to contact erosion and a drastically shortened lifespan (usually difficult to reach 10,000 operations). Sudden current changes during switching can cause a step or "jitter" in the output torque, severely affecting the smoothness of operation. Furthermore, a single controller needs to drive two sets of windings with drastically different parameter characteristics (impedance, inductance, etc.), making it difficult to achieve optimal matching of control parameters, often resulting in decreased current control accuracy, efficiency loss, or deteriorated dynamic response.

[0010] Therefore, there is an urgent need for an innovative motor to fundamentally solve the above-mentioned technical contradictions and achieve a balance of high efficiency, smooth operation, and reliability in both high and low speed conditions. Summary of the Invention

[0011] To address the shortcomings of existing technologies, this invention provides an axial flux motor with a stator dual-winding structure, which has the advantages of independent switching between high and low speeds and no electric arc or torque impact during switching, thus solving the problem that traditional motors cannot simultaneously achieve high and low speed performance.

[0012] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0013] An axial flux motor with a stator dual winding structure includes multiple stators and multiple rotors arranged along the motor axis; the number of rotors is even and greater than the number of stators; the rotors are provided with permanent magnets arranged in a Halebeck array.

[0014] The number of stators is odd; a stator is provided between any two adjacent rotors; the stator is provided with a first winding combination for low-speed drive and a second winding combination for high-speed drive; all the first winding combinations of the stator are connected in series to form a low-speed coil, and all the second winding combinations of the stator are connected in parallel to form a high-speed coil.

[0015] A first controller is connected to the low-speed coil via a first busbar;

[0016] The second controller is connected to the high-speed coil via a second busbar; both controllers are semiconductor relays.

[0017] A control unit, which is connected to the first controller and the second controller, is used to control the first controller and the second controller according to torque requirements to energize the low-speed coil or the high-speed coil.

[0018] Preferably, the stator includes a disk with two sets of winding slots; both sets of winding slots are arranged in a circular array and are concentric; the diameter of the circle corresponding to one set of winding slots is larger than the diameter of the circle corresponding to the other set of winding slots.

[0019] The disk has an insulating layer on its exterior.

[0020] Preferably, the stator includes a disk with multiple sets of winding slots arranged in a circular array; each set includes two winding slots, which are symmetrically arranged about the diameter of the circle; the outer contour of the structure formed by each set of winding slots is the same as the shape of a permanent magnet of the rotor.

[0021] The disk has an insulating layer on its exterior.

[0022] Preferably, the number of turns of the low-speed coil is greater than the number of turns of the high-speed coil, the wire diameter of the low-speed coil is smaller than the wire diameter of the high-speed coil, and the resistance of the low-speed coil is greater than the resistance of the high-speed coil.

[0023] Preferably, a radial heat dissipation pipe is provided on the disk and between two adjacent sets of winding slots; the disk is also provided with annular return pipes located at both ends of the heat dissipation pipes; the annular return pipes are provided with an inlet pipe and an outlet pipe for connecting to the cooler.

[0024] Preferably, each stator's high-speed coil and low-speed coil include a U-phase winding, a V-phase winding, and a W-phase winding, each winding having a start end and a tail end.

[0025] Preferably, the low-speed coils are connected in series as follows:

[0026] In the axial direction of the motor, the starting end of the U-phase winding of the stator at the first position is the starting point, which is connected to the U-phase starting terminal of the first busbar; the ending end of the U-phase winding of the stator at the last position is the ending point, which is connected to the U-phase ending terminal of the first busbar; the U-phase windings of the stator between the first and last positions are configured such that the starting end of the U-phase winding of the stator at the current position is connected in series with the ending end of the U-phase winding of the stator at the previous position, and the ending end of the U-phase winding of the stator at the current position is connected in series with the starting end of the U-phase winding of the stator at the next position.

[0027] In the axial direction of the motor, the starting end of the V-phase winding of the stator at the first position is the starting point, which is connected to the starting terminal of the V-phase winding of the first busbar; the ending end of the V-phase winding of the stator at the last position is the ending point, which is connected to the ending terminal of the V-phase winding of the first busbar; the V-phase windings of the stator between the first and last positions are configured such that: the starting end of the V-phase winding of the stator at the current position is connected in series with the ending end of the V-phase winding of the stator at the previous position, and the ending end of the V-phase winding of the stator at the current position is connected in series with the starting end of the V-phase winding of the stator at the next position.

[0028] In the axial direction of the motor, the starting end of the W-phase winding of the stator at the first position is the starting point, which is connected to the starting terminal of the W-phase winding of the first busbar; the ending end of the W-phase winding of the stator at the last position is the ending point, which is connected to the ending terminal of the W-phase winding of the first busbar; the W-phase windings of the stator between the first and last positions are configured such that the starting end of the W-phase winding of the current position is connected in series with the ending end of the W-phase winding of the previous position, and the ending end of the W-phase winding of the current position is connected in series with the starting end of the W-phase winding of the next position.

[0029] Preferably, the high-speed coils are connected in parallel as follows:

[0030] In the axial direction of the motor, the starting ends of all stator U-phase windings are connected to the U-phase starting terminal of the second busbar; the tail ends of all stator U-phase windings are connected to the U-phase tail terminal of the second busbar.

[0031] In the axial direction of the motor, the starting ends of all stator V-phase windings are connected to the V-phase starting terminal of the second busbar; the tail ends of all stator V-phase windings are connected to the V-phase tail terminal of the second busbar.

[0032] In the axial direction of the motor, the starting ends of all stator W-phase windings are connected to the starting terminal of the second busbar; the ending ends of all stator W-phase windings are connected to the ending terminal of the second busbar.

[0033] Preferably, a current-sharing reactor is also connected in parallel to the second bus.

[0034] Preferably, the stator dual-winding axial flux motor further includes a busbar housing, which is located outside the outer shell of the stator dual-winding axial flux motor; the busbar housing has two spaced-apart mounting chambers; the first busbar and the second busbar are disposed in the corresponding mounting chambers.

[0035] Compared with the prior art, the present invention provides an axial flux motor with a stator dual-winding structure, which has the following beneficial effects:

[0036] First, at the structural level, by setting an even number of rotors with Halbach arrays and an odd number of stators to be stacked alternately, a magnetic circuit with high power density and axial magnetic self-balancing is constructed, laying the physical foundation for the motor to achieve high performance.

[0037] The core lies in the decoupling of electromagnetic design. The solution integrates two sets of windings with drastically different parameters in each stator: the first windings of all stators are connected in series to form a low-speed coil, giving it high resistance and high inductance characteristics, optimized for low-speed, high-torque, low-current, and high-efficiency operation; the second windings are connected in parallel to form a high-speed coil, giving it low resistance and low inductance characteristics, optimized for high-speed operation, easy magnetization weakening, and high efficiency. This fundamentally solves the contradiction that a single set of winding parameters, with its fixed parameters, cannot accommodate a wide range of operating conditions.

[0038] The key breakthrough lies in the innovation of the switching mechanism. By employing semiconductor relays and intelligently coordinating two independent controllers through a control unit, completely electronic switching without mechanical contacts is achieved. This not only completely eliminates reliability bottlenecks such as arc erosion and wear, but also, with the help of precise software control, achieves millisecond-level, current-instantaneous, and smooth torque transition mode switching, solving the problem of jerking during mechanical switching.

[0039] Ultimately, the integration results in a balance of performance, reliability, and safety. This solution enables a single motor platform to seamlessly switch between optimal low-speed and optimal high-speed characteristics adaptively. Furthermore, the dual-winding, dual-controller architecture provides natural redundancy, ensuring derating operation even in the event of partial failures. This meets the stringent requirements of aerospace and high-end vehicle industries for both extreme performance and ultra-high reliability in drive systems. Attached Figure Description

[0040] Figure 1 This is a distribution diagram of the stator and rotor of the axial flux motor with a stator dual winding structure according to the present invention;

[0041] Figure 2 This is a schematic diagram of the stator three-dimensional structure of the present invention;

[0042] Figure 3 This is a three-dimensional structural diagram of a stator and rotor according to the present invention;

[0043] Figure 4 This is a schematic diagram of the winding slot distribution of the first type of stator of the present invention;

[0044] Figure 5 This is a schematic diagram of the second type of winding slot distribution in the stator of the present invention;

[0045] Figure 6 This is a schematic diagram of the stator of the present invention with heat dissipation function;

[0046] Figure 7 This is a schematic diagram of the structure of the manifold housing of the present invention;

[0047] Figure 8 This is a schematic diagram of the first winding combination connected in series to form a low-speed coil according to the present invention;

[0048] Figure 9 This is a schematic diagram of the second winding combination connected in parallel to form a high-speed coil according to the present invention.

[0049] In the diagram: 1. Stator; 2. Rotor; 3. First winding assembly; 4. Second winding assembly; 5. First controller; 6. First busbar; 7. Second controller; 8. Second busbar; 9. Heat sink; 10. Annular return pipe; 11. Control unit; 12. Current sharing reactor; 13. Busbar housing. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] As described in the background section, there are shortcomings in the existing technology. In order to solve the above-mentioned technical problems, this application proposes an axial flux motor with a stator dual winding structure.

[0052] Please see Figures 1-7 An axial flux motor with a stator dual winding structure includes multiple stators 1 and multiple rotors 2 arranged along the motor axis. The number of rotors 2 is even and greater than the number of stators 1. The rotors 2 are provided with permanent magnets arranged in a Halebeck array.

[0053] The number of stators 1 is odd; a stator 1 is set between any two adjacent rotors 2; the stator 1 is provided with a first winding combination 3 for low-speed drive and a second winding combination 4 for high-speed drive; all the first winding combinations 3 of the stator 1 are connected in series to form a low-speed coil, and all the second winding combinations 4 of the stator 1 are connected in parallel to form a high-speed coil.

[0054] The first controller 5 is connected to the low-speed coil via the first bus 6;

[0055] The second controller 7 is connected to the high-speed coil via the second bus 8; the second controller 7 is a semiconductor relay.

[0056] Control unit 11, which is connected to first controller 5 and second controller 7, is used to control first controller 5 and second controller 7 according to torque requirements to energize low-speed coil or high-speed coil.

[0057] With the above structure, the number of rotors 2 is even and greater than the number of stators 1. This forms an axial magnetic flux topology with multiple rotors 2 clamping fewer stators 1, which increases the effective air gap area and the number of magnetic circuit couplings. As a result, the power density and torque density of the motor are greatly improved without significantly increasing the motor diameter.

[0058] The rotor uses a Halbach array, which can concentrate and enhance the magnetic field on the air gap side. On the one hand, it increases the air gap magnetic flux density, thereby increasing torque and power. On the other hand, it weakens the stray magnetic field on the back of the rotor, allowing the use of thinner magnets and rotor yokes, thus achieving the lightweight and compact design of the motor.

[0059] The number of stators 1 is odd, and a stator 1 is placed between any two adjacent rotors 2 to form a symmetrical and balanced magnetic pull layout. The odd number of stators 1 is symmetrically clamped by the even number of rotors 2, so that the net magnetic attraction force on the motor in the axial direction is basically canceled out, which greatly reduces the axial load on the bearings and improves mechanical reliability and life.

[0060] The stator 1 is equipped with a first winding combination for low-speed drive and a second winding combination for high-speed drive. Through a single motor structure, two electromagnetic systems with different parameters and characteristics are integrated, enabling the motor to have a wide operating range covering low speed and high torque as well as high speed and high efficiency. This solves the fundamental contradiction of the traditional single-winding motor, which cannot achieve both high and low speed performance, from a physical perspective.

[0061] The first winding is connected in series to form a low-speed coil, which increases the total resistance and total inductance of the low-speed coil. This makes it require less current to generate large torque under a given voltage, thereby significantly reducing copper losses under low-speed, high-current conditions and improving efficiency in the low-speed region.

[0062] The second winding is connected in parallel to form a high-speed coil, reducing the total resistance and total inductance of the high-speed coil. Low resistance helps reduce current conduction losses in the high-speed region; low inductance greatly enhances the motor's "field weakening" speed-up capability, enabling the motor to maintain constant power output in a range far exceeding the base speed, thus meeting the requirements for high-speed cruising.

[0063] The first and second controllers are connected to the low-speed and high-speed coils respectively, achieving specialization and decoupling of the controllers. Each controller can perform optimized hardware design and software parameter tuning for the electrical parameters of its corresponding winding, such as resistance, inductance, and back EMF constant. This avoids the parameter trade-offs and control performance degradation that occur when a single controller drives two sets of windings with different characteristics, thereby accurately optimizing the control accuracy, dynamic response, and efficiency under low-speed and high-speed conditions respectively.

[0064] The second controller is a semiconductor relay. The control unit is used to control the switching according to torque requirements, realizing electronic switching without mechanical contacts. The semiconductor relay eliminates the inherent problems of mechanical switches such as contact erosion, arcing, and short lifespan, and can achieve up to hundreds of millions of lossless switching operations, fundamentally solving the reliability bottleneck of traditional mechanical switching solutions.

[0065] The control unit intelligently determines the timing and process of switching based on real-time torque, speed, and other requirements using software algorithms. Combined with the rapid response capability of semiconductor relays, it can achieve smooth mode switching with millisecond-level response, no current surge, and no torque interruption, completely eliminating the jitter and jerkiness problems caused by mechanical switching.

[0066] In some embodiments, reference is made to Figures 2-4 As shown, the stator 1 includes a disk with two sets of winding slots; both sets of winding slots are arranged in a circular array and are concentric; the diameter of the circle corresponding to one set of winding slots is larger than the diameter of the circle corresponding to the other set of winding slots.

[0067] The outside of the disk is covered with an insulating layer.

[0068] In this embodiment, the winding slots are arranged in a concentric circular array with different diameters. The technical effect is to provide a clear and efficient axially layered winding layout scheme. Completely separating the low-speed and high-speed windings radially into inner and outer rings facilitates their respective winding, insulation, and cooling, simplifying the manufacturing process. Windings of different diameters can be better matched with cooling systems with different flow channels, such as inner and outer spiral oil channels, achieving targeted and efficient heat dissipation. Appropriate radial separation can reduce the mutual inductance between the two windings to a certain extent, reducing electromagnetic interference during switching.

[0069] In some embodiments, reference is made to Figure 5 As shown, the stator 1 includes a disk with multiple sets of winding slots arranged in a circular array on the disk; each set includes two winding slots, which are symmetrically arranged with the diameter of the circle as the axis of symmetry; the outer contour of the structure formed by each set of winding slots is the same as the shape of a permanent magnet of the rotor 2.

[0070] The outside of the disk is covered with an insulating layer.

[0071] In this embodiment, the winding slots are arranged in groups, with each group corresponding to the shape of a rotor permanent magnet and arranged symmetrically, providing a distributed winding layout that precisely matches the Halbach rotor poles.

[0072] The winding slot shape corresponds to the magnetic pole profile, allowing the effective edges of the coil to be more concentrated in the main magnetic field region of the air gap, improving winding utilization and motor torque density. The symmetrical layout, matched to the magnetic poles, makes fuller use of the effective space on the stator disk, accommodating more copper wire within a limited volume and increasing power. This layout helps generate a back electromotive force closer to a sine wave, reducing torque ripple and resulting in smoother motor operation and lower noise.

[0073] In some embodiments, the number of turns of the low-speed coil is greater than the number of turns of the high-speed coil, the wire diameter of the low-speed coil is smaller than the wire diameter of the high-speed coil, and the resistance of the low-speed coil is greater than the resistance of the high-speed coil.

[0074] In this implementation, the core electromagnetic parameter design principles for achieving performance differentiation between high and low speeds are as follows: Low-speed coil: more turns → higher back EMF constant → greater torque under the same current; small wire diameter, high resistance → matching low current operating mode → optimizing copper loss in the low-speed range.

[0075] High-speed coils: fewer turns → lower back EMF constant → allow for higher rotational speeds and easier magnetic field weakening; large wire diameter and low resistance → allow for larger currents and lower losses → meet high-speed constant power requirements.

[0076] In some embodiments, reference is made to Figure 6 As shown, a radial heat dissipation pipe 9 is provided on the disk and between two adjacent sets of winding slots; the disk is also provided with annular return pipes 10 located at both ends of the heat dissipation pipe 9; the annular return pipes 10 are provided with an inlet pipe and an outlet pipe for connecting with the cooler.

[0077] In this embodiment, radial heat dissipation pipes and annular return pipes are arranged in the stator disk, disclosing a high-efficiency liquid cooling heat dissipation method that is directly embedded in the stator body.

[0078] Cooling pipes are laid directly between the winding slots, enabling close-range and highly efficient heat dissipation from the heat-generating windings. This solves the severe heat dissipation challenge faced by coreless stators due to the lack of a core heat conduction path. The cooling pipes are integrated with the stator structure, without occupying additional axial space, maintaining the overall compactness of the motor. Radial flow channels, combined with annular return pipes, guide the coolant to flow evenly across the entire stator disk surface, preventing localized overheating and ensuring the motor's continuous operation and insulation life under high power density.

[0079] In some embodiments, each stator 1's high-speed and low-speed coils include a U-phase winding, a V-phase winding, and a W-phase winding, each winding having a start end and a tail end. This is because the stator windings of a three-phase motor generally consist of three independent windings, corresponding to the U, V, and W phases respectively. Each winding has two terminals, a start end and a tail end, which are typically marked as U1, U2, V1, V2, W1, and W2, and are used for connecting to the power supply or wiring.

[0080] Among them, reference Figure 8 As shown, the low-speed coils are connected in series as follows:

[0081] In the axial direction of the motor, the starting end of the U-phase winding of the stator 1 at the first position is the starting point, which is connected to the U-phase starting terminal of the first busbar 6; the ending end of the U-phase winding of the stator 1 at the last position is the ending point, which is connected to the U-phase ending terminal of the first busbar 6; the U-phase windings of the stator 1 between the first and last positions are configured as follows: the starting end of the U-phase winding of the stator 1 at the current position is connected in series with the ending end of the U-phase winding of the stator 1 at the previous position, and the ending end of the U-phase winding of the stator 1 at the current position is connected in series with the starting end of the U-phase winding of the stator 1 at the next position.

[0082] In the axial direction of the motor, the starting end of the V-phase winding of the stator 1 at the first position is the starting point, which is connected to the starting terminal of the V-phase winding of the first busbar 6; the ending end of the V-phase winding of the stator 1 at the last position is the ending point, which is connected to the ending terminal of the V-phase winding of the first busbar 6; the V-phase windings of the stator 1 between the first and last positions are configured such that the starting end of the V-phase winding of the stator 1 at the current position is connected in series with the ending end of the V-phase winding of the stator 1 at the previous position, and the ending end of the V-phase winding of the stator 1 at the current position is connected in series with the starting end of the V-phase winding of the stator 1 at the next position.

[0083] In the axial direction of the motor, the starting end of the W-phase winding of the stator 1 at the first position is the starting point, which is connected to the starting terminal of the W-phase winding of the first busbar 6; the ending end of the W-phase winding of the stator 1 at the last position is the ending point, which is connected to the ending terminal of the W-phase winding of the first busbar 6; the W-phase windings of the stator 1 between the first and last positions are configured as follows: the starting end of the W-phase winding of the stator 1 at the current position is connected in series with the ending end of the W-phase winding of the stator 1 at the previous position, and the ending end of the W-phase winding of the stator 1 at the current position is connected in series with the starting end of the W-phase winding of the stator 1 at the next position.

[0084] Among them, reference Figure 9 As shown, the high-speed coils are connected in parallel as follows:

[0085] In the axial direction of the motor, the first end of all U-phase windings of stator 1 is connected to the first U-phase terminal of the second busbar 8; the last end of all U-phase windings of stator 1 is connected to the last U-phase terminal of the second busbar 8.

[0086] In the axial direction of the motor, the first end of all V-phase windings of stator 1 is connected to the first V-phase terminal of the second busbar 8; the last end of all V-phase windings of stator 1 is connected to the last V-phase terminal of the second busbar 8.

[0087] In the axial direction of the motor, the starting ends of all W-phase windings of stator 1 are connected to the starting terminal of the W-phase of the second busbar 8; the ending ends of all W-phase windings of stator 1 are connected to the ending terminal of the W-phase of the second busbar 8.

[0088] The above provides a specific and unique implementation scheme for the axial series connection between multiple stators, clarifying that the current flows in from the first stator, flows through the in-phase windings of all stators in sequence, and then flows out, forming an electrically continuous and branchless series circuit.

[0089] This paper describes the parallel connection method of three-phase high-speed windings among multiple stators, clarifying that the beginning and end of all stator windings of the same phase are connected in parallel, forming a standard parallel circuit topology. This completely determines the connection relationship of the high-speed parallel coils, which is the basis for subsequent current sharing design and bus design.

[0090] In some embodiments, reference is made to Figure 7 As shown, a current-sharing reactor 12 is also connected in parallel on the second busbar 8.

[0091] The parallel current-sharing reactor 12 connected to the second busbar 8 actively solves the problem of current balance in the parallel branches of the high-speed winding.

[0092] Due to manufacturing tolerances and differences in connection resistance, the impedances of parallel branches may vary slightly, leading to uneven current distribution. Current-sharing reactors utilize their inductive reactance to compensate for branches with higher impedance, forcibly controlling the current differences between parallel branches to a minimal range.

[0093] Current balancing ensures that the temperature rise of each stator high-speed winding is consistent, avoiding local overheating; at the same time, it makes the output of all windings uniform, giving full play to the advantages of the parallel structure, and ensuring efficiency, power output and long-term operational reliability under high-speed conditions.

[0094] In some embodiments, the stator dual-winding axial flux motor further includes a bus housing 13, which is located outside the outer shell of the stator dual-winding axial flux motor; the bus housing 13 has two spaced-apart mounting chambers; the first bus 6 and the second bus 8 are disposed in the corresponding mounting chambers.

[0095] By setting up independent busbar housings and installing the first and second busbars in separate chambers, the modularity, safety, and electromagnetic compatibility optimization of the electrical connection system are achieved.

[0096] By isolating the high-voltage, high-current busbars from the internal rotating parts of the motor and the external environment, operational safety and dust and water resistance are improved. The busbars, connection points, current-sharing reactors, etc., are concentrated in the external housing, which facilitates installation, inspection and maintenance, and improves the maintainability of the product.

[0097] Working principle: When using:

[0098] The low-speed, high-torque drive mode is suitable for take-off, landing, and starting operations.

[0099] When the control unit 11 determines that a large torque and low speed output is needed based on external instructions, such as the accelerator pedal or internal algorithms, the system enters low speed mode.

[0100] Circuit conduction path: Control unit 11 instructs first controller 5 to start and supplies power to low-speed coil through first bus 6. At the same time, it instructs second controller 7 and semiconductor relay connected to high-speed coil to be in the off state, ensuring that high-speed coil is completely isolated from the circuit.

[0101] Low-speed coil operation: All first windings of stator 1, group 3, are in operation. Because this coil is connected in series, its total resistance, total inductance, and back EMF constant are large.

[0102] Torque generation mechanism: The first controller 5 outputs three-phase alternating current, generating a rotating magnetic field in the low-speed coil. This magnetic field interacts with the strong air gap magnetic field generated by the Halbach array on the rotor 2, producing an electromagnetic force. Due to the large torque constant Kt of the low-speed coil, according to the formula torque T = Kt × current I, a very large torque can be output with a relatively small phase current, satisfying the powerful ground-pushing effect required for eVTOL vertical takeoff and landing or the instantaneous acceleration of supercars.

[0103] Efficiency advantage: In this mode, although the coil resistance is relatively large, the required operating current is optimized and reduced. According to Joule's law, copper loss = current² × resistance, the total copper loss is effectively controlled, achieving high-efficiency output at low speed and high torque.

[0104] High-speed, high-efficiency drive mode, suitable for cruising, high-speed driving and other operating conditions.

[0105] When the motor speed reaches or exceeds the set base speed and the torque demand decreases, entering the constant power operating range with efficiency as the core, the system switches to high-speed mode.

[0106] Circuit conduction path: Control unit 11 instructs the second controller 7 and its connected semiconductor relay to conduct, supplying power to the high-speed coil through the second busbar 8. At the same time, it instructs the first controller 5 and the low-speed coil circuit to turn off.

[0107] High-speed coil operation: All second winding combinations 4 of stator 1 are in operation. Because the coils are connected in parallel, their total resistance is low, their total inductance is low, and their back EMF constant Ke is small.

[0108] High-speed and field-weakening speed-enhancing mechanism: The second controller 7 outputs a higher-frequency three-phase AC power to match the high speed. Due to the low inductance of the high-speed coil, its field-weakening control response is rapid and efficient. By injecting direct-axis current, the controller actively weakens the air gap magnetic field, ensuring that the motor's back EMF remains below the bus voltage limit even when the speed far exceeds the base speed. This significantly widens the motor's constant-power speed regulation range, meeting the requirements of high-speed cruising.

[0109] Efficiency and Current Sharing Advantages: In this mode, the low resistance characteristic reduces current conduction losses. The parallel branch, through the synergistic effect of the second busbar 8 and the current sharing reactor 12, ensures that the current is evenly distributed among the high-speed coils of the four stators, avoiding local overheating and efficiency loss caused by uneven current, and achieving global high efficiency in the high-speed range.

[0110] Seamless switching process of operating modes

[0111] When operating conditions, such as speed and torque requirements, change and it is necessary to switch between low-speed and high-speed modes, the control unit 11 executes a precise switching procedure.

[0112] Switching decision: The control unit 11 monitors parameters such as speed, torque, and efficiency MAP in real time, and automatically determines the switching timing based on a preset algorithm.

[0113] Assuming a switch from low speed to high speed, the control unit first instructs the first controller 5 to smoothly reduce its output current to zero in a ramp manner.

[0114] The system detects that the phase current of the low-speed coil is indeed zero. At the moment the current is zero, the control unit turns off the semiconductor relay connected to the low-speed coil and then turns on the semiconductor relay connected to the high-speed coil. Because the switching occurs at the current zero-crossing point and semiconductor devices are used, there is absolutely no arcing, and there are no issues with mechanical contact bouncing or burning.

[0115] After the high-speed side semiconductor relay is turned on, the second controller 7 starts immediately and establishes the required current and torque in a ramp manner. The entire switching process is completed within 10ms, with uninterrupted torque transmission and no significant fluctuations in speed, thus ensuring the ultimate smoothness when switching eVTOL flight modes or shifting gears in the vehicle.

[0116] Fault detection and standby operation mode

[0117] Control unit 11 and two controllers monitor the current, voltage, temperature, insulation status, etc. of their respective circuits in real time. Any abnormality, such as overcurrent, overheating, open circuit, or short circuit, will be immediately identified and located.

[0118] If the low-speed coil or the first controller 5 malfunctions, the control unit will force the motor to switch to high-speed mode. In this case, the high-speed coil and its controller will independently undertake the driving task. Although the maximum output power and low-speed torque may be limited, it is sufficient to ensure safe eVTOL cruise or for the vehicle to reach a safe location.

[0119] Conversely, if the high-speed system malfunctions, it will be forcibly switched to and locked in low-speed mode. In this mode, although the motor cannot reach its maximum speed, it can still provide sufficient low-speed torque to ensure basic mobility.

[0120] This redundancy capability enables the system to meet the high reliability requirements of applications such as automotive functional safety ASIL D level or similar applications.

[0121] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An axial flux motor with a stator double winding structure, comprising a plurality of stators (1) and a plurality of rotors (2) arranged along the motor axial direction, characterized in that: The number of rotors (2) is even and greater than the number of stators (1); the rotors (2) are provided with permanent magnets arranged in a Halebeck array; The number of stators (1) is odd; a stator (1) is set between any two adjacent rotors (2); the stator (1) is provided with a first winding combination (3) for low-speed drive and a second winding combination (4) for high-speed drive; the first winding combinations (3) of all stators (1) are connected in series to form a low-speed coil, and the second winding combinations (4) of all stators (1) are connected in parallel to form a high-speed coil; A first controller (5) is connected to the low-speed coil via a first busbar (6); The second controller (7) is connected to the high-speed coil via the second bus (8); the second controller (7) is a semiconductor relay. The control unit (11) is connected to the first controller (5) and the second controller (7) and is used to control the first controller (5) and the second controller (7) according to the torque demand so as to energize the low-speed coil or the high-speed coil.

2. An axial flux motor with a stator double winding structure according to claim 1, characterized in that: The stator (1) includes a disk with two sets of winding slots. Both sets of winding slots are arranged in a circular array and are concentric. The diameter of the circle corresponding to one set of winding slots is larger than the diameter of the circle corresponding to the other set of winding slots. The disk has an insulating layer on its exterior.

3. An axial flux motor with a stator double winding structure according to claim 1, characterized in that: The stator (1) includes a disk, on which multiple sets of winding slots are arranged in a circular array; each set includes two winding slots, which are symmetrically arranged with the diameter of the circle as the axis of symmetry; the outer contour of the structure formed by each set of winding slots is the same as the shape of a permanent magnet of the rotor (2). The disk has an insulating layer on its exterior.

4. An axial flux motor with a stator double winding structure according to claim 2 or 3, characterized in that: The low-speed coil has more turns than the high-speed coil, the wire diameter of the low-speed coil is smaller than that of the high-speed coil, and the resistance of the low-speed coil is greater than that of the high-speed coil.

5. An axial flux motor with a stator double winding structure according to claim 3, characterized in that: The disk is provided with radial heat dissipation pipes (9) located between two adjacent sets of winding slots; the disk is also provided with annular return pipes (10) located at both ends of the heat dissipation pipes (9); the annular return pipes (10) are provided with inlet pipes and outlet pipes for connecting with the cooler.

6. An axial flux motor with a stator double winding structure according to claim 1, characterized in that: Each stator (1) includes a U-phase winding, a V-phase winding, and a W-phase winding in its high-speed and low-speed coils, each winding having a start end and a tail end.

7. An axial flux motor with a stator double winding structure according to claim 6, characterized in that: The low-speed coils are connected in series as follows: In the direction of the motor axis, the starting end of the U-phase winding of the stator (1) at the first position is the starting point, and the starting point is connected to the U-phase starting terminal of the first busbar (6); the ending end of the U-phase winding of the stator (1) at the last position is the ending point, and the ending end is connected to the U-phase ending terminal of the first busbar (6); the U-phase winding of the stator (1) between the stator (1) at the first position and the stator (1) at the last position is configured as follows: the starting end of the U-phase winding of the stator (1) at the current position is connected in series with the ending end of the U-phase winding of the stator (1) at the previous position, and the ending end of the U-phase winding of the stator (1) at the current position is connected in series with the starting end of the U-phase winding of the stator (1) at the next position. In the direction of the motor axis, the starting end of the V-phase winding of the stator (1) at the first position is the starting point, and the starting point is connected to the V-phase starting terminal of the first busbar (6); the ending end of the V-phase winding of the stator (1) at the last position is the ending point, and the ending end is connected to the V-phase ending terminal of the first busbar (6); the V-phase windings of the stator (1) between the stator (1) at the first position and the stator (1) at the last position are configured as follows: the starting end of the V-phase winding of the stator (1) at the current position is connected in series with the ending end of the V-phase winding of the stator (1) at the previous position, and the ending end of the V-phase winding of the stator (1) at the current position is connected in series with the starting end of the V-phase winding of the stator (1) at the next position. In the direction of the motor axis, the starting end of the W-phase winding of the stator (1) at the first position is the starting point, and the starting point is connected to the W-phase starting terminal of the first busbar (6); the ending end of the W-phase winding of the stator (1) at the last position is the ending point, and the ending end is connected to the W-phase ending terminal of the first busbar (6); the W-phase windings of the stator (1) between the stator (1) at the first position and the stator (1) at the last position are configured as follows: the starting end of the W-phase winding of the stator (1) at the current position is connected in series with the ending end of the W-phase winding of the stator (1) at the previous position, and the ending end of the W-phase winding of the stator (1) at the current position is connected in series with the starting end of the W-phase winding of the stator (1) at the next position.

8. An axial flux motor with a stator double winding structure according to claim 6, characterized in that: The high-speed coils are connected in parallel as follows: In the direction of the motor axis, the first end of the U-phase winding of all stators (1) is connected to the first end terminal of the U-phase of the second busbar (8); the tail end of the U-phase winding of all stators (1) is connected to the tail end terminal of the U-phase of the second busbar (8). In the direction of the motor axis, the first end of the V phase winding of all stators (1) is connected to the first end terminal of the V phase of the second busbar (8); the last end of the V phase winding of all stators (1) is connected to the last end terminal of the V phase of the second busbar (8). In the direction of the motor axis, the first end of the W phase winding of all stators (1) is connected to the first end terminal of the W phase of the second busbar (8); the last end of the W phase winding of all stators (1) is connected to the last end terminal of the W phase of the second busbar (8).

9. An axial flux motor with a stator double winding structure according to claim 1, characterized in that: A current-sharing reactor (12) is also connected in parallel on the second bus (8).

10. An axial flux motor with a stator double winding structure according to claim 9, characterized in that: The stator double-winding structure axial flux motor also includes a bus housing (13), which is located on the outside of the outer shell of the stator double-winding structure axial flux motor; the bus housing (13) has two spaced-apart mounting chambers; the first bus (6) and the second bus (8) are located in the corresponding mounting chambers.

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