An annular air gap magnetic field adjustable hybrid magnetic circuit

Abstract

This invention discloses an adjustable hybrid magnetic circuit with annular air gap magnetic field, belonging to the field of motor and electromagnetic device technology. It adopts an axisymmetric annular permanent magnet pole and electromagnetic coil configuration design, which structurally ensures the full-domain axisymmetry of the annular air gap magnetic field. By integrating the synergistic excitation architecture of permanent magnet and electromagnetic coil, efficient series coupling of permanent magnet magnetomotive force and electromagnetic magnetomotive force is achieved under the special topological constraints of the annular closed air gap. The permanent magnet magnetic circuit provides the basic magnetic field and reduces energy consumption. The electromagnetic coil performs fine magnetic field adjustment. By precisely controlling the magnitude and direction of the excitation current, the magnetic flux density of the annular air gap is smoothly changed, realizing flexible adjustment of the air gap magnetic flux density. This solves the problems of the non-adjustable magnetic field of traditional fixed air gap permanent magnet circuits and the high power consumption of electromagnetic coils.

Description

Technical Field

[0001] This invention belongs to the field of motor and electromagnetic device technology, specifically relating to a hybrid magnetic circuit with adjustable annular air gap magnetic field. Background Technology

[0002] The toroidal liquid metal magnetohydrodynamic generator is a magnetohydrodynamic power generation device that uses low-melting-point liquid metal as the conductive fluid and adopts a toroidal flow channel structure. The liquid metal continuously circulates within the toroidal flow channel, eliminating the need for additional complex return pipelines. It features a compact structure, small size, and fast start-up response. It can achieve stable rated output of the main generator under high operating conditions for wind power generation, tidal power generation, and aerodynamic wave power generation. At the same time, it increases power output, improves the efficiency of the main generator, and enhances the utilization rate of renewable energy resources.

[0003] The toroidal liquid metal magnetohydrodynamic generator requires a toroidal axisymmetric axial magnetic field. As a high-performance energy regulation device, it needs to adjust the power output in real time according to wind speed, flow velocity, and wave height to ensure that the main generator operates stably and efficiently under rated conditions. During operation, the only adjustable variable is the magnetic flux density.

[0004] Existing technology adopts Figure 1 (The arrows indicate the magnetization direction, and the origin of the cylindrical coordinate system is at the geometric center of the magnetic circuit.) The magnetic circuit structure shown has several cylindrical permanent magnet poles evenly distributed along the circumference, generating a circumferentially periodically distributed axial magnetic field within the annular air gap. A servo motor drives a mechanical mechanism to move the cylindrical permanent magnet poles, thereby changing the axial spacing between the poles to control the magnetic flux density of the annular air gap. Figure 2 (Where, the horizontal axis represents the azimuth angle θ in degrees, and the vertical axis represents the Z-direction component B of the magnetic flux density at the air gap center.) z As shown in the figure (unit: Tesla (T)), the axial component Bz of the magnetic flux density in the annular air gap exhibits a circumferential periodic distribution, which differs significantly from the required ideal axisymmetric magnetic field. The Z-direction component Bz of the magnetic flux density at different circumferential positions... z Inconsistencies directly affect the uniformity of the electrical, magnetic, and flow field distribution within the generator, thereby reducing external output characteristics. Furthermore, existing magnetic field regulation systems have complex mechanical structures, numerous intermediate transmission and control links, and slow system response speeds, failing to quickly keep up with dynamic changes in external operating conditions and severely limiting the actual operating performance of the generator. This invention aims to solve the engineering challenges of toroidal liquid metal magnetohydrodynamic (MHD) generators, particularly focusing on the problem of the inability to dynamically adapt the magnetic flux density of toroidal liquid metal MHD generators to wind speed, flow velocity, and wave height in large-scale renewable energy power generation scenarios, ultimately achieving real-time, high-precision control of the toroidal air gap magnetic flux density. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A toroidal air-gap magnetic field adjustable hybrid magnetic circuit includes:

[0007] Upper combined magnetic poles, lower combined magnetic poles, annular air gap and The yoke frame is shaped; the upper combined magnetic pole, the annular air gap, and the lower combined magnetic pole are arranged axially from top to bottom in the following order: Within the central annular space of the yoke frame, the upper and lower combined magnetic poles are arranged symmetrically about the annular air gap;

[0008] The upper combined magnetic pole includes an upper inner coil, an upper annular permanent magnet pole, and an upper outer coil arranged coaxially in the radial direction; the lower combined magnetic pole includes a lower inner coil, a lower annular permanent magnet pole, and a lower outer coil arranged coaxially in the radial direction.

[0009] The upper inner coil and the lower inner coil have the same number of turns and are energized with the first unidirectional excitation current. The upper outer coil and the lower outer coil have the same number of turns and are energized with the second unidirectional excitation current. The first unidirectional excitation current and the second unidirectional excitation current are in opposite directions.

[0010] The present invention has the following beneficial effects:

[0011] This invention achieves full-domain axisymmetry of the annular air gap magnetic field by employing an axisymmetric and coaxial configuration design of annular permanent magnet poles and electromagnetic coils.

[0012] This invention integrates a ring-shaped permanent magnet pole that provides the basic magnetic field with an electromagnetic coil that can precisely control the magnitude and direction of the excitation current, thereby constructing a permanent magnet-electromagnetic synergistic excitation architecture. This simultaneously solves two technical problems: the magnetic field of the traditional fixed air gap permanent magnet circuit is not adjustable, and the power consumption of the pure electromagnetic coil is high. This enables flexible and smooth adjustment of the air gap magnetic flux density and low-energy operation.

[0013] This invention utilizes axisymmetry The yoke frame structure significantly reduces the total magnetic reluctance of the magnetic circuit. At the same time, the two-pole magnetic circuit configuration and the efficient series coupling mechanism of permanent magnet potential and electromagnetic potential are combined to enhance the total magnetic potential of the magnetic circuit. From the two dimensions of magnetic reluctance optimization and magnetic potential enhancement, the leakage magnetic field of the periphery is suppressed and the effective magnetic field is enhanced. Finally, a high magnetic flux density working magnetic field is formed in the centimeter-level annular air gap.

[0014] This invention employs an inner and outer coil configuration arranged coaxially with completely opposite current directions, which essentially cancels out the magnetic field of the internal cylindrical air gap space enclosed by the inner coil to a near-zero state. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a permanent magnet circuit in the prior art;

[0016] Figure 2 This is a schematic diagram of the axial component of magnetic flux density in the Z=0 plane of a conventional permanent magnet circuit, distributed circumferentially along the center line of the air gap.

[0017] Figure 3 This is a three-dimensional schematic diagram of a quarter section of the adjustable hybrid magnetic circuit with annular air gap of the present invention: 1-upper combined magnetic pole, 2-annular air gap, 3-lower combined magnetic pole, 4- Type yoke frame, 1-1-upper inner coil, 1-2-upper annular permanent magnet pole, 1-3-upper outer coil, 3-1-lower inner coil, 3-2-lower annular permanent magnet pole, 3-3-lower outer coil, RR axis, ZZ axis;

[0018] Figure 4 This is a schematic diagram of the RZ plane magnetic field line distribution of the annular air gap adjustable hybrid magnetic circuit of the present invention (the electromagnetic coil generates a magnetic field in the +Z direction in the annular air gap);

[0019] Figure 5 This is a schematic diagram of the RZ plane magnetic field line distribution of the annular air gap adjustable hybrid magnetic circuit of the present invention (the electromagnetic coil generates a magnetic field in the -Z direction in the annular air gap);

[0020] Figure 6 This is the Z-direction component B of the magnetic flux density in a specific embodiment of the present invention. z A schematic diagram showing the distribution along the center line of the air gap. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] A hybrid magnetic circuit with adjustable magnetic field in annular air gap, comprising upper combined magnetic pole 1, annular air gap 2, lower combined magnetic pole 3, and... The frame consists of a yoke frame 4. The upper combined magnetic pole 1, the annular air gap 2, and the lower combined magnetic pole 3 are arranged in... The annular space in the middle of the yoke frame 4. The annular air gap magnetic field adjustable hybrid magnetic circuit geometry is axisymmetric, and any RZ (radial-axial) plane is symmetric about the R axis (the origin of the cylindrical coordinates is at the geometric center of the magnetic circuit). The upper combined magnetic pole 1 includes an upper inner coil 1-1, an upper annular permanent magnet pole 1-2, and an upper outer coil 1-3 arranged coaxially in the radial direction. The lower combined magnetic pole 3 includes a lower inner coil 3-1, a lower annular permanent magnet pole 3-2, and a lower outer coil 3-3 arranged coaxially in the radial direction. The upper combined magnetic pole 1 and the lower combined magnetic pole 3 are symmetrically arranged at a certain distance along the axial direction, and this distance is on the order of centimeters. The axial distance between the upper annular permanent magnet pole 1-2 and the lower annular permanent magnet pole 3-2 is on the order of centimeters. The annular space between the upper annular permanent magnet pole 1-2 and the lower annular permanent magnet pole 3-2 is the annular air gap 2. The yoke frame 4 is arranged around the outer periphery of the upper combined magnetic pole 1 and the lower combined magnetic pole 3. It is positioned between each pair of the upper inner coil 1-1, the upper annular permanent magnet pole 1-2, and the upper outer coil 1-3, as well as at the upper ends of the upper inner coil 1-1, the upper annular permanent magnet pole 1-2, and the upper outer coil 1-3, and along the axial outer periphery of the upper outer coil 1-3. An insulating layer is provided between the frame 4 of the yoke. The lower inner coil 3-1, the lower annular permanent magnet pole 3-2, and the lower outer coil 3-3 are positioned between each other, as well as at the lower ends of the lower inner coil 3-1, the lower annular permanent magnet pole 3-2, and the lower outer coil 3-3, and along the axial outer periphery of the lower outer coil 3-3. An insulating layer is provided between the frame 4 of the yoke. The upper inner coil 1-1 and the lower inner coil 3-1 both have N1 turns of wire and are energized with a first unidirectional excitation current I1. The upper outer coil 1-3 and the lower outer coil 3-3 both have N2 turns of wire and are energized with a second unidirectional excitation current I2. I1 and I2 are in opposite directions. The upper annular permanent magnet pole 1-2 and the lower annular permanent magnet pole 3-2 are both magnetized axially and in the same direction. In any RZ plane, magnetic field lines pass through the annular air gap 2-upper combined pole 1- The yoke frame 4-lower combined magnetic pole 3 is closed. To achieve flexible and smooth adjustment of the magnetic flux density in the annular air gap, the magnitude and direction of I1 and I2 are adjusted, thereby adjusting the magnitude and direction of the magnetic field generated by the upper inner coil 1-1, upper outer coil 1-3, lower inner coil 3-1, and lower outer coil 3-3 in the annular air gap 2, so that it is the same as or opposite to the direction of the magnetic field generated by the upper annular permanent magnet pole 1-2 and lower annular permanent magnet pole 3-2 in the annular air gap 2; by adjusting the ampere-turns N1I1 of the upper inner coil 1-1 and lower inner coil 3-1 and the ampere-turns N2I2 of the upper outer coil 1-3 and lower outer coil 3-3, the magnetic flux density in the cylindrical air gap space within the upper inner coil 1-1 and lower inner coil 3-1 can be made very small, or even close to 0.

[0023] The adjustable hybrid magnetic circuit with annular air gap magnetic field consists of 4 electromagnetic coils, 2 annular permanent magnet poles, 1 annular air gap 2, and 1... The system consists of a 4-type yoke frame; four electromagnetic coils, including one inner coil and one outer coil; one inner coil, one annular permanent magnet pole, and one outer coil are arranged coaxially along the radial direction to form one combined magnetic pole. The annular air gap magnetic field adjustable hybrid magnetic circuit includes two combined magnetic poles: an upper combined magnetic pole 1 and a lower combined magnetic pole 3. The upper combined magnetic pole 1 and the lower combined magnetic pole 3 are symmetrically arranged at a centimeter-level interval along the axial direction. The annular space between the two annular permanent magnet poles, with an axial distance of centimeters, is the annular air gap 2. The yoke frame 4 is arranged on the outer periphery of the upper combined magnetic pole 1 and the lower combined magnetic pole 3; the annular air gap magnetic field adjustable hybrid magnetic circuit geometry has axisymmetry, and any RZ plane is symmetric about the R axis (the origin of the cylindrical coordinate is at the center of the magnetic circuit geometry).

[0024] The technical solution of the present invention will be described below with reference to the accompanying drawings.

[0025] Figures 3-6 In a specific embodiment of the present invention, the origin of the cylindrical coordinate system is at the geometric center of the magnetic circuit.

[0026] like Figure 3 The adjustable hybrid magnetic route of the annular air gap magnetic field of the present invention consists of an upper combined magnetic pole 1, an annular air gap 2, a lower combined magnetic pole 3, and... The frame consists of a 4-shaped yoke. The upper combined magnetic pole 1, the annular air gap 2, and the lower combined magnetic pole 3 are arranged axially from top to bottom. Within the annular space of the yoke frame 4, the upper combined magnetic pole 1 and the lower combined magnetic pole 3 are symmetrically arranged about the annular air gap 2. The adjustable hybrid magnetic circuit of the annular air gap magnetic field of this invention has an axisymmetric structure and is symmetrical about the R (radial) axis in any RZ (cylindrical coordinate system) plane. The upper combined magnetic pole 1 consists of an upper inner coil 1-1, an upper annular permanent magnet pole 1-2, and an upper outer coil 1-3, all of the same height and arranged radially from the inside out. The lower combined magnetic pole 3 consists of a lower inner coil 3-1, a lower annular permanent magnet pole 3-2, and a lower outer coil 3-3, all of the same height and arranged radially from the inside out. The annular air gap 2 is located between the upper annular permanent magnet pole 1-2 and the lower annular permanent magnet pole 3-2, with an axial height on the order of centimeters. The spaces between each pair of the upper inner coil 1-1, the upper annular permanent magnet pole 1-2, and the upper outer coil 1-3, as well as the upper ends of the upper inner coil 1-1, the upper annular permanent magnet pole 1-2, and the upper outer coil 1-3, and the axial outer periphery of the upper outer coil 1-3. An insulating layer is provided between the frame 4 of the yoke iron, between each pair of the lower inner coil 3-1, the lower annular permanent magnet pole 3-2, and the lower outer coil 3-3, as well as at the lower ends of the lower inner coil 3-1, the lower annular permanent magnet pole 3-2, and the lower outer coil 3-3, and on the axial outer periphery of the lower outer coil 3-3. An insulating layer is provided between the 4-type yoke frame.

[0027] Figure 4This is a schematic diagram of the RZ plane magnetic field line distribution of the adjustable hybrid magnetic circuit in the annular air gap of the present invention (the electromagnetic coil generates a magnetic field in the +Z direction in the annular air gap). Figure 5 This is a schematic diagram of the RZ plane magnetic field line distribution of the annular air gap adjustable hybrid magnetic circuit of the present invention (the electromagnetic coil generates a magnetic field in the -Z direction in the annular air gap). Figure 4 , Figure 5 The arrows in the diagram indicate the magnetization directions of the upper annular permanent magnet pole 1-2 and the lower annular permanent magnet pole 3-2. × indicates that the current is perpendicular to the coil cross section and flows outwards, while × indicates that the current is perpendicular to the coil cross section and flows inwards. Figure 4 In the middle section, the upper inner coil 1-1 and the lower inner coil 3-1 both have N1 turns of wire and are supplied with the first unidirectional excitation current I1, with the current direction perpendicular to the coil cross-section outwards. The upper outer coil 1-3 and the lower outer coil 3-3 both have N2 turns of wire and are supplied with the second unidirectional excitation current I2, with the current direction perpendicular to the coil cross-section inwards. The ampere-turns N1I1 equals N2I2, generating a Z (axial) positive direction and a magnitude of B within the annular air gap 2. e The magnetic field; the magnetization direction of the upper annular permanent magnet pole 1-2 and the lower annular permanent magnet pole 3-2 is the positive Z-axis direction, generating a magnetic field with a magnitude of B0 in the positive Z-axis direction in the annular air gap 2; the magnetic field lines are closed through the lower combined magnetic pole 3 → annular air gap 2 → upper combined magnetic pole 1 → yoke frame 4, and the magnitude of the Z-direction component of the magnetic flux density in the annular air gap 2 is the sum of Be and B0. Figure 5 Adjust the excitation current direction of the upper inner coil 1-1, the lower inner coil 3-1, the upper outer coil 1-3, and the lower outer coil 3-3 so that they generate a magnetic field in the annular air gap 2 that is opposite to the direction of the upper annular permanent magnet pole 1-2 and the lower annular permanent magnet pole 3-2. Figure 4 and Figure 5 It can also be seen that, except for the annular air gap 2, The absence of magnetic field lines on the outer perimeter of the yoke frame 4 and in the central cylindrical region of the magnetic circuit indicates that the magnetic flux density is very small.

[0028] Figure 6 To change the direction and magnitude of the excitation current, the Z-direction component of the magnetic flux density B z The distribution along the centerline of the annular air gap 2 (Z=0 plane), where the vertical axis represents the Z-direction component B of the magnetic flux density at the air gap center. z The unit is Tesla (T), and the horizontal axis is the azimuth angle θ, with the unit being °. This indicates that the magnetic field within the annular air gap 2 is generated solely by the annular permanent magnet poles; other parameters are similar to those of the annular permanent magnet poles. Figure 4 and Figure 5 The corresponding scenario indicates that the magnetic field within the annular air gap is generated jointly by the annular permanent magnet poles and the electromagnetic coil. Figure 6 It can be seen that B zThe uniform distribution along the circumference indicates that the annular air gap magnetic field of this invention possesses global axisymmetry. Changing the magnitude and direction of the excitation current affects the Z-direction component B of the magnetic flux density at the air gap center. z In [B0-B e B0+B e The range varies within a certain range, and the magnetic field adjustment range is 2B. e When the upper annular permanent magnet pole 1-2 and the lower annular permanent magnet 3-2 are neodymium iron boron (N50) with an axial thickness of 32 mm, the ampere-turns of the four electromagnetic coils are... With an ampere-turn capacity and an annular air gap axial height of 18mm, when the excitation current direction is changed, the electromagnetic coil and permanent magnet poles generate a magnetic field in the same direction within the air gap. When the electromagnetic coil and the permanent magnet pole generate opposite magnetic fields in the air gap, .

[0029] The above description is merely an embodiment of the present invention and does not limit the scope of the invention. Any equivalent structural or procedural transformations made based on the description and drawings of this invention, or direct or indirect applications in other related system fields, are similarly included within the protection scope of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A hybrid magnetic circuit with adjustable annular air gap magnetic field, characterized in that, include: Upper combined magnetic poles, lower combined magnetic poles, annular air gap and The yoke frame is shaped; the upper combined magnetic pole, the annular air gap, and the lower combined magnetic pole are arranged axially from top to bottom in the following order: Within the central annular space of the yoke frame, the upper and lower combined magnetic poles are arranged symmetrically about the annular air gap; The upper combined magnetic pole includes an upper inner coil, an upper annular permanent magnet pole, and an upper outer coil arranged coaxially in the radial direction; the lower combined magnetic pole includes a lower inner coil, a lower annular permanent magnet pole, and a lower outer coil arranged coaxially in the radial direction. The upper inner coil and the lower inner coil have the same number of turns and are energized with the first unidirectional excitation current. The upper outer coil and the lower outer coil have the same number of turns and are energized with the second unidirectional excitation current. The first unidirectional excitation current and the second unidirectional excitation current are in opposite directions.

2. The annular air gap magnetic field adjustable hybrid magnetic circuit according to claim 1, characterized in that, The magnetization direction of both the upper and lower annular permanent magnet poles is axial, and the magnetization directions are the same.

3. The annular air gap adjustable hybrid magnetic circuit according to claim 1, characterized in that, The annular air gap magnetic field adjustable hybrid magnetic circuit is an axisymmetric structure and is symmetric about the R axis in any RZ plane.

4. The annular air gap adjustable hybrid magnetic circuit according to claim 1, characterized in that, The upper inner coil, the upper annular permanent magnet pole, the upper outer coil, the upper inner coil, the upper annular permanent magnet pole, the upper outer coil, and the axial outer periphery of the upper outer coil are all connected. An insulating layer is provided between the frame frames of the yoke.

5. The annular air gap magnetic field adjustable hybrid magnetic circuit according to claim 1, characterized in that, The lower inner coil, the lower annular permanent magnet pole, the lower outer coil, and the lower inner coil, the lower annular permanent magnet pole, the lower outer coil, and the axial outer periphery of the lower outer coil are all connected. An insulating layer is provided between the frame frames of the yoke.

6. The annular air gap magnetic field adjustable hybrid magnetic circuit according to claim 1, characterized in that, Adjusting the magnitude and direction of the first and second co-directional excitation currents, thereby adjusting the magnitude and direction of the magnetic field generated by the upper inner coil, upper outer coil, lower inner coil, and lower outer coil in the annular air gap, so that it is the same as or opposite to the direction of the magnetic field generated by the upper and lower annular permanent magnet poles in the annular air gap.

7. The annular air gap magnetic field adjustable hybrid magnetic circuit according to claim 1, characterized in that, Adjust the ampere-turns of the upper inner coil and the lower inner coil, as well as the ampere-turns of the upper outer coil and the lower outer coil, so that the magnetic flux density of the cylindrical air gap space inside the upper inner coil and the lower inner coil approaches zero.

8. The annular air gap adjustable hybrid magnetic circuit according to claim 1, characterized in that, The axial height of the annular air gap is on the order of centimeters.

9. The annular air gap adjustable hybrid magnetic circuit according to claim 1, characterized in that, The upper and lower magnetic poles are symmetrically arranged at a certain distance along the axial direction, and this distance is on the order of centimeters.

10. The annular air gap magnetic field adjustable hybrid magnetic circuit according to claim 1, characterized in that, The axial distance between the upper and lower annular permanent magnet poles is on the order of centimeters.

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