A dual-stator axial flux motor

Abstract

The present invention discloses a dual-stator axial flux motor. In this axial flux motor, the first stator winding is connected using a star connection method, and the second stator winding is connected using a delta connection method. The first and second stator windings are connected using a specific connection method, and the second stator leads the first stator by a specific angle along the rotation direction of the axial flux motor to ensure that the vector directions of the first fundamental wave and the second fundamental wave remain the same, while minimizing the superposition of the first target harmonic and the second target harmonic. The present invention does not require the introduction of additional adjustment components. The purpose of weakening the target harmonic can be achieved simply by selecting the connection method of the first and second stator windings and changing the relative positions of the first and second stators. The operation is simple and easy to implement.

Description

Technical Field

[0001] The present invention relates to the technical field of axial flux motors, and more particularly to a dual-stator axial flux motor. Background Art

[0002] Concentrated-winding axial-flux motors are widely used due to their simple manufacturing process, high power and torque density, low cogging torque, compact end ferrules, and minimal copper wire usage. However, compared to traditional distributed windings, concentrated windings generate abundant magnetic field harmonics when current is applied. These harmonics, especially low-order harmonics, increase eddy current losses and core losses, and worsen vibration and noise, severely impacting motor performance. Dual-stator axial-flux motors also suffer from these drawbacks. Summary of the Invention

[0003] The purpose of the present invention is to weaken the target harmonics while keeping the amplitude of the fundamental wave unchanged. To achieve the above purpose, the present invention provides the following technical solutions:

[0004] A dual-stator axial flux motor includes a stator having a stator winding, the stator winding generating magnetic field harmonics, the magnetic field harmonics including target harmonics and a fundamental wave, the stator including a first stator and a second stator, and correspondingly, the stator winding including a first stator winding and a second stator winding, the magnetic field harmonics including a first magnetic field harmonic and a second magnetic field harmonic, the target harmonics including a first target harmonic and a second target harmonic, and the fundamental wave including a first fundamental wave and a second fundamental wave;

[0005] The first stator winding is connected in a star connection manner, the second stator winding is connected in a delta connection manner, and the first stator winding and the second stator winding are connected in a specific connection manner. The second stator leads the first stator by a specific angle along the rotation direction of the axial flux motor, so that the vector directions of the first fundamental wave and the second fundamental wave remain the same, and the superposition of the first target harmonic and the second target harmonic is minimized.

[0006] Preferably, the specific angle is k / p, p is the spatial order of the first fundamental wave and the second fundamental wave, k = 30°, 150°, 270°, for the first target harmonic and the second target harmonic with a spatial order of n, the value of k is determined by maximizing cos[(nk / pk) / 2] or cos[(nk / p+k) / 2], and different k corresponds to different specific wiring methods.

[0007] Preferably, the first stator winding includes an A1 phase winding, a B1 phase winding, and a C1 phase winding, and the second stator winding includes an A2 phase winding, a B2 phase winding, and a C2 phase winding;

[0008] The A1 phase winding is connected to the connection point between the A2 phase and the B2 phase, the B1 phase winding is connected to the connection point between the B2 phase and the C2 phase, the C1 phase winding is connected to the connection point between the A2 phase and the C2 phase, and k=30°.

[0009] Preferably, the first stator winding includes an A1 phase winding, a B1 phase winding, and a C1 phase winding, and the second stator winding includes an A2 phase winding, a B2 phase winding, and a C2 phase winding;

[0010] The A1 phase winding is connected to the connection point between the A2 phase and the C2 phase, the B1 phase winding is connected to the connection point between the A2 phase and the B2 phase, the C1 phase winding is connected to the connection point between the B2 phase and the C2 phase, and k=150°.

[0011] Preferably, the first stator winding includes an A1 phase winding, a B1 phase winding, and a C1 phase winding, and the second stator winding includes an A2 phase winding, a B2 phase winding, and a C2 phase winding;

[0012] The A1 phase winding is connected to the connection point between the B2 phase and the C2 phase, the B1 phase winding is connected to the connection point between the A2 phase and the C2 phase, the C1 phase winding is connected to the connection point between the A2 phase and the B2 phase, and k=270°.

[0013] Preferably, the n is calculated by simulation software, and the p is equal to the number of pole pairs of the axial flux motor.

[0014] Preferably, the axial flux motor is an 18-slot, 16-pole six-phase axial flux motor, the rotation direction of the first target harmonic and the second target harmonic in the axial flux motor is opposite to the rotation direction of the axial flux motor, and the spatial order of the first target harmonic and the second target harmonic is 10, the spatial order of the first fundamental wave and the second fundamental wave is 8, and k=270°.

[0015] Preferably, the number of turns of the coil of the first winding is N1, the number of turns of the coil of the second winding is N2, and N2 is The rounded integer value.

[0016] It can be seen from the above technical solution that: the present invention adopts a star connection method to connect the first stator winding, adopts a delta connection method to connect the second stator winding, adopts a specific connection method to connect the first stator winding and the second stator winding, and at the same time rotates the second stator at a specific angle relative to the first stator so that the vector directions of the first fundamental wave and the second fundamental wave remain the same, and at the same time minimizes the superposition of the first target harmonic and the second target harmonic.

[0017] In the axial flux motor of the present invention, no additional adjustment components need to be introduced. The purpose of weakening the target harmonics can be achieved simply by selecting the connection method of the first stator winding and the second stator winding, and by changing the relative positions of the first stator and the second stator. The operation is simple and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of a dual-stator structure of an axial flux motor provided in a specific embodiment of the present invention;

[0020] Figure 2 for Figure 1 The main view;

[0021] Figure 3 A schematic diagram of a second stator provided in a specific embodiment of the present invention after being rotated α degrees relative to the first stator;

[0022] Figure 4 A schematic diagram of vector synthesis of a first target harmonic and a second target harmonic provided in a specific embodiment of the present invention;

[0023] Figure 5 A wiring diagram of a first wiring method provided by a specific embodiment of the present invention;

[0024] Figure 6 A wiring diagram of a second wiring method provided in a specific embodiment of the present invention;

[0025] Figure 7 A wiring diagram of a third wiring method provided by a specific embodiment of the present invention;

[0026] Figure 8 This is a comparison diagram of the magnetic field harmonics generated by the 18-slot 16-pole axial flux motor provided by a specific embodiment of the present invention and the magnetic field harmonics generated by the traditional solution.

[0027] Among them, 1 is the first stator, 1-1 is the first stator winding, 2 is the second stator, 2-1 is the second stator winding, and 3 is the rotor. DETAILED DESCRIPTION

[0028] The present invention discloses a dual-stator axial flux motor, which can not only weaken the target harmonics but also keep the amplitude of the fundamental wave unchanged.

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] The present invention discloses a dual-stator axial flux motor, which includes a stator having a stator winding. When energized, the stator winding generates magnetic field harmonics. The magnetic field harmonics include target harmonics and fundamental waves. The target harmonics are waves that cause the axial flux motor to vibrate, and therefore need to be eliminated. The fundamental wave is a useful wave, and therefore needs to be retained. The axial flux motor in the present invention includes two stators and a rotor 3, as shown in the attached figure. Figure 1 and attached Figure 2 As shown, the two stators are respectively a first stator 1 and a second stator 2. Correspondingly, the stator windings include a first stator winding 1-1 and a second stator winding 2-1, the magnetic field harmonics include a first magnetic field harmonic and a second magnetic field harmonic, the target harmonics include a first target harmonic and a second target harmonic, and the fundamental waves include a first fundamental wave and a second fundamental wave.

[0031] In the present invention, a star connection method is adopted for connecting the first stator winding, a delta connection method is adopted for connecting the second stator winding, a specific connection method is adopted for connecting the first stator winding and the second stator winding, and the second stator is rotated by a specific angle relative to the first stator so that the vector directions of the first fundamental wave and the second fundamental wave remain the same, and the superposition of the first target harmonic and the second target harmonic is minimized.

[0032] In the dual-stator axial flux motor of the present invention, no additional adjustment components need to be introduced. The purpose of weakening the target harmonics can be achieved simply by selecting the connection method of the first stator winding and the second stator winding, and by changing the relative positions of the first stator and the second stator. The operation is simple and easy to implement.

[0033] There are three specific connection methods between the first stator winding and the second stator winding. Under each specific connection method, the initial phase angle of the current of the second stator winding will lag behind the initial phase angle of the current of the first stator winding by k degrees, and each specific connection method corresponds to a determined k value. If the initial phase angle of the current of the second stator winding lags behind the initial phase angle of the current of the first stator winding, then the vector angle between the first fundamental wave and the second fundamental wave will be k, and the amplitude of the fundamental wave will be reduced. In order to eliminate the vector angle, the present invention changes the relative position of the first stator and the second stator. Specifically, the second stator is rotated k / p degrees relative to the first stator along the direction of rotation of the axial flux motor. P is the spatial order of the first fundamental wave and the second fundamental wave. The superposition of the first target harmonic and the second target harmonic is a function of k. The k value is deduced based on the principle of minimizing the value of the function, thereby determining the specific connection method.

[0034] It should be noted that if the stator rotates a certain angle, the corresponding fundamental wave will rotate by p times the angle, where p is the spatial order of the fundamental wave. Therefore, if the second fundamental wave is to be rotated by k degrees in the same direction as the rotation direction of the axial flux motor, the second stator is rotated by k / p degrees in the same direction as the rotation direction of the axial flux motor. Please refer to the attached Figure 3 , in the attached Figure 3 The second stator winding 2 - 1 is rotated by α degrees relative to the first stator winding 1 - 1 , that is, the second stator is rotated by α relative to the first stator, α=k / p.

[0035] For a six-phase axial flux motor, if the first stator winding is connected in star connection and the second stator winding is connected in delta connection, there are three possible connection methods between the first and second stator windings:

[0036] The first one is, please refer to the attached Figure 5 , A1, B1, and C1 phase windings are connected in star connection, A2, B2, and C2 are connected in delta connection, A1 phase winding is connected to the connection point between A2 and B2 phases, B1 phase winding is connected to the connection point between B2 and C2 phases, and C1 phase winding is connected to the connection point between A2 and C2 phases. At this time, k = 30°.

[0037] The second one is, please refer to the attached Figure 6 The A1, B1, and C1 phase windings are connected in star connection, and the A2, B2, and C2 phases are connected in delta connection. The A1 phase winding is connected to the connection point between the A2 phase and the C2 phase, the B1 phase winding is connected to the connection point between the A2 phase and the B2 phase, and the C1 phase winding is connected to the connection point between the B2 phase and the C2 phase. At this time, k = 150°.

[0038] The third type is: Please refer to the attached Figure 7The A1, B1, and C1 phase windings are connected in star connection, and the A2, B2, and C2 phases are connected in delta connection. The A1 phase winding is connected to the connection point between the B2 phase and the C2 phase, the B1 phase winding is connected to the connection point between the A2 phase and the C2 phase, and the C1 phase winding is connected to the connection point between the A2 phase and the B2 phase. At this time, k = 270°.

[0039] It should be noted that A1, B1, C1, A2, B2, and C2 involved in this article are only for the convenience of describing the connection method of the six-phase winding, and do not limit the first stator winding to have A1, B1, and C1 phase windings, and the second stator winding to have A2, B2, and C2 phase windings.

[0040] If the initial phase angle of the current of the second stator lags k degrees relative to the initial phase angle of the current of the first stator, and the second stator rotates k / p relative to the first stator in the same direction as the rotation direction of the axial flux motor, then, when the rotation direction of the first target harmonic and the second target harmonic is the same as the rotation direction of the axial flux motor, the second target harmonic rotates θ1 degrees relative to the first target harmonic in the same direction as the rotation direction of the axial flux motor, θ1 = (nk / pk) degrees; when the rotation direction of the first target harmonic and the second target harmonic is opposite to the rotation direction of the axial flux motor, the second target harmonic rotates θ2 degrees relative to the first target harmonic in the same direction as the rotation direction of the axial flux motor, θ2 = (nk / p+k) degrees, where n is the spatial order of the target harmonic.

[0041] If the second target harmonic rotates by θ1 = (nk / pk) degrees relative to the first target harmonic, then the vector angle between the second target harmonic and the first target harmonic is θ1 = (nk / pk) degrees. Figure 4 The vector sum of the first and second target harmonics is the diagonal of a rhombus formed by the vectors of the first and second target harmonics. The direction of the vector sum points from the intersection of the vectors of the first and second target harmonics to the opposite vertex of the rhombus. The magnitude of the vector sum is the length of the corresponding diagonal. The amplitudes of the first and second target harmonics are the same, both Bm. According to the rhombus diagonal calculation formula, the magnitude of the vector sum is 2*Bm*cos(θ1 / 2). Since θ1 = (nk / pk), the magnitude of the vector sum is 2*Bm*cos[(nk / pk) / 2]. Similarly, if the angle between the vectors of the second target harmonic and the first target harmonic is θ2 = (nk / p+k), then the magnitude of the vector sum is 2*Bm*cos[(nk / p+k) / 2].

[0042] It should be noted that n is the spatial order of the target harmonic, and p is the spatial order of the fundamental wave. The spatial order of the target harmonic for an axial flux motor can be calculated through software simulation. The spatial order p of the fundamental wave is equal to the pole pair number of the axial flux motor. The composite of the first and second target harmonics is a trigonometric function of k. For the same motor model, the spatial order n of the target harmonic and the spatial order p of the fundamental wave are both fixed, and the rotation direction of the target harmonic is also fixed. Substitute k = 30°, 150°, and 270° into cos[(nk / pk) / 2] or cos[(nk / p+k) / 2], respectively, and compare the value of k that minimizes the vector sum. This determines the value of k, and thus the specific wiring method. If the determined k value is 30°, the first wiring method is selected; if the determined k value is 150°, the second wiring method is selected; and if the determined k value is 270°, the third wiring method is selected.

[0043] In a specific embodiment of the present invention, the axial flux motor is a six-phase axial flux motor with 18 slots and 16 poles. That is, the axial flux motor is a dual-stator motor, and each stator includes a three-phase winding. In this axial flux motor, the rotation direction of the first and second target harmonics is opposite to that of the axial flux motor. The first and second target harmonics are both 10th-order opposite harmonics. The spatial order of the first and second fundamental waves is 8. Therefore, the combined value of the first and second target harmonics is 2*Bm*cos9k / 8. Therefore, the vector sum amplitude is minimum when k = 270°. Accordingly, the third connection method should be selected. Specifically, the first stator winding of the axial flux motor is connected in a star connection, and the second stator winding is connected in a delta connection. Then, the A1 phase winding is connected to the connection point between the A2 and C2 phases, the B1 phase winding is connected to the connection point between the A2 and B2 phases, and the C1 phase winding is connected to the connection point between the B2 and C2 phases.

[0044] If the first stator winding is connected in star connection and the second stator winding is connected in delta connection, then the current value in the first stator winding is the square root of 3 times the current value in the second stator winding. The magnetic flux density of the harmonic is proportional to the number of turns of the winding and the current value of the winding. In order to ensure that the magnetic flux density of the harmonics of the first stator winding and the second stator winding is equal, thereby avoiding axial vibration of the axial flux motor, the present invention limits the number of turns N2 in the second stator winding to the square root of 3 times the number of turns N1 in the first stator winding. Therefore, the number of turns is a positive integer, so N2 is taken as The rounded integer value.

[0045] Please refer to the attached Figure 8 , attached Figure 8A comparison diagram of the magnetic field harmonics formed by the 18-slot 16-pole axial flux motor provided by a specific embodiment of the present invention and the magnetic field harmonics formed by the traditional solution. Figure 8 It can be seen that the amplitude of the target 10th-order harmonic is greatly weakened, while the amplitude of the fundamental wave (8th-order) remains basically unchanged. In addition, the 2nd-order harmonic is also greatly weakened, indicating that this solution can effectively weaken specific low-order harmonics.

[0046] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. The terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0047] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0048] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A dual-stator axial flux motor, characterized in that: The stator comprises a stator having a stator winding, the stator winding generating magnetic field harmonics, the magnetic field harmonics including a target harmonic and a fundamental wave, the stator comprising a first stator and a second stator, and correspondingly, the stator winding comprising a first stator winding and a second stator winding, the magnetic field harmonics including a first magnetic field harmonic and a second magnetic field harmonic, the target harmonics including a first target harmonic and a second target harmonic, and the fundamental wave including a first fundamental wave and a second fundamental wave; The first stator winding is connected in a star connection manner, the second stator winding is connected in a delta connection manner, and the first stator winding and the second stator winding are connected in a specific connection manner, so that the initial phase angle of the current of the second stator winding lags the initial phase angle of the current of the first stator winding by k degrees; and the second stator leads the first stator by a specific angle along the rotation direction of the axial flux motor, so that the second stator rotates k / p degrees relative to the first stator along the rotation direction of the axial flux motor, where P is the spatial order of the first fundamental wave and the second fundamental wave; so that the vector directions of the first fundamental wave and the second fundamental wave remain the same, and at the same time, the superposition of the first target harmonic and the second target harmonic is minimized.

2. The dual-stator axial flux motor according to claim 1, characterized in that: The specific angle is k / p, where p is the spatial order of the first fundamental wave and the second fundamental wave, and k = 30°, 150°, and 270°. For the first target harmonic and the second target harmonic with a spatial order of n, the value of k is determined by maximizing cos[(nk / pk) / 2] or cos[(nk / p+k) / 2]. Different k corresponds to different specific wiring methods.

3. The dual-stator axial flux motor according to claim 2, characterized in that: The first stator winding includes an A1 phase winding, a B1 phase winding, and a C1 phase winding, and the second stator winding includes an A2 phase winding, a B2 phase winding, and a C2 phase winding; The A1 phase winding is connected to the connection point between the A2 phase and the B2 phase, the B1 phase winding is connected to the connection point between the B2 phase and the C2 phase, the C1 phase winding is connected to the connection point between the A2 phase and the C2 phase, and k=30°.

4. The dual-stator axial flux motor according to claim 2, characterized in that: The first stator winding includes an A1 phase winding, a B1 phase winding, and a C1 phase winding, and the second stator winding includes an A2 phase winding, a B2 phase winding, and a C2 phase winding; The A1 phase winding is connected to the connection point between the A2 phase and the C2 phase, the B1 phase winding is connected to the connection point between the A2 phase and the B2 phase, the C1 phase winding is connected to the connection point between the B2 phase and the C2 phase, and k=150°.

5. The dual-stator axial flux motor according to claim 2, characterized in that: The first stator winding includes an A1 phase winding, a B1 phase winding, and a C1 phase winding, and the second stator winding includes an A2 phase winding, a B2 phase winding, and a C2 phase winding; The A1 phase winding is connected to the connection point between the B2 phase and the C2 phase, the B1 phase winding is connected to the connection point between the A2 phase and the C2 phase, the C1 phase winding is connected to the connection point between the A2 phase and the B2 phase, and k=270°.

6. The dual-stator axial flux motor according to claim 2, characterized in that: The n is calculated by simulation software, and the p is equal to the number of pole pairs of the axial flux motor.

7. The dual-stator axial flux motor according to claim 2, characterized in that: The axial flux motor is a six-phase axial flux motor with 18 slots and 16 poles. The rotation direction of the first target harmonic and the second target harmonic in the axial flux motor is opposite to the rotation direction of the axial flux motor, and the spatial order of the first target harmonic and the second target harmonic is 10, the spatial order of the first fundamental wave and the second fundamental wave is 8, and k=270°.

8. The dual-stator axial flux motor according to claim 1, characterized in that: The number of turns of the coil of the first stator winding is N1, and the number of turns of the coil of the second stator winding is N2. The rounded integer value.

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