Permanent magnet biased radial magnetic suspension bearing

Abstract

According to the permanent magnet biased radial magnetic suspension bearing, a stator comprises a stator iron core which is annularly arranged, a plurality of teeth which extend out in the radial direction are arranged on the inner circumference of the stator iron core, and a permanent magnet is arranged at the end of each tooth; the coils are arranged on the teeth in a one-to-one correspondence mode. For each radial degree of freedom of the rotor, a plurality of coils are selected from the coil units to form a control winding in a series-parallel connection mode; the controller is used for applying a forward or reverse control signal to the control winding according to the offset of the rotor at the corresponding radial degree of freedom; the power amplifier is used for amplifying the forward or reverse control signal of the controller; and the displacement sensor is used for detecting the offset of the rotor at the corresponding radial degree of freedom in real time, and the controller outputs a control current instruction according to the offset. According to the invention, the rotor can be stably suspended by distributing small control current, and the number of power amplifiers is greatly reduced.

Description

Technical Field

[0001] This invention relates to magnetic levitation bearing technology, and particularly to a permanent magnet biased radial magnetic levitation bearing. Background Technology

[0002] Existing motors use mechanical bearings for support, which are limited by bearing friction and rotor vibration, resulting in low-speed operation, low power density, and low efficiency. Furthermore, mechanical bearings consume a lot of energy, have poor reliability, and cause significant noise and oil pollution. In contrast, high-speed motors supported by magnetic bearings eliminate friction and wear. Since magnetic bearings require no lubrication, high-speed motors can reach speeds of tens of thousands of revolutions per minute. They offer advantages such as high power density, high energy efficiency, small size, light weight, and fast response, making them ideal support components for the future development of high-speed rotating power machinery.

[0003] Figure 1 The diagram shown is of an existing radial magnetic levitation bearing structure, as follows: Figure 1 As shown, the existing radial magnetic levitation bearing consists of a control coil 102, a stator core 101, a rotor core 103, and related insulation structures. When current is applied to the coil, the stator core 101 can exert an attractive force on the rotor core 103 in the X and Y directions, respectively. Under the combined action of the relative X+\X- and Y+\Y- magnetic forces, the rotor is constrained. The control part of the radial magnetic levitation bearing mainly includes a sensor, a controller, and a power amplifier. When the sensor detects rotor displacement, it adjusts the current in the corresponding direction to make the rotor return to the correct position.

[0004] Figure 2 The diagram shown is a control block diagram of an existing system using radial magnetic levitation bearings, such as... Figure 2 As shown, the existing control system for radial magnetic levitation bearings requires two power amplifiers on each of the x and y axes for a single radial magnetic levitation bearing, for a total of four power amplifiers. This results in significant overall power loss, and the increased circuitry also leads to greater process complexity, lower fault tolerance, and relatively complex control. Summary of the Invention

[0005] The purpose of this invention is to provide a permanent magnet biased radial magnetic levitation bearing to solve the problems of the prior art.

[0006] This invention discloses a permanent magnet biased radial magnetic levitation bearing, comprising: a stator, a rotor, and a control winding; the stator includes a stator core arranged in a ring, with a plurality of radially extending teeth on the inner circumference of the stator core, each tooth tip being provided with a permanent magnet; a plurality of coils are correspondingly arranged on each tooth; for each radial degree of freedom of the rotor, a plurality of coils are selected from the coil unit and connected in series and parallel to form a control winding; a controller is used to apply a positive or negative control signal to the control winding according to the rotor's offset in the corresponding radial degree of freedom; a power amplifier amplifies the positive or negative control signal from the controller, thereby generating a controllable bidirectional radial attraction in the direction of the corresponding single radial degree of freedom, keeping the rotor in a centrally suspended position; a displacement sensor is used to detect the rotor's offset in the corresponding radial degree of freedom in real time, and the controller outputs a control current command according to the offset.

[0007] According to one embodiment of the permanent magnet biased radial magnetic levitation bearing of the present invention, the permanent magnet is a magnetic steel.

[0008] According to one embodiment of the permanent magnet biased radial magnetic levitation bearing of the present invention, a plurality of radially extending teeth are an even number, arranged periodically in the order of two adjacent N poles followed by two adjacent S poles to generate a magnetic pole circuit. The magnetic pole circuit interacts with radially opposite opposite poles to generate a control magnetic field with one degree of freedom. Under the combined action of the two opposite magnetic poles, the rotor shaft of the motor is constrained on the x-axis and y-axis.

[0009] According to one embodiment of the permanent magnet biased radial magnetic levitation bearing of the present invention, the coils constituting the same degree of freedom control winding are divided into two branches, each branch is composed of at least two coils connected in series, and the two branches are then connected in parallel and driven by a power amplifier.

[0010] According to one embodiment of the permanent magnet biased radial magnetic levitation bearing of the present invention, when the power amplifier applies a positive current to the corresponding control winding, the coil in one branch generates an electromagnetic polarity consistent with the direction of the corresponding magnet to enhance the permanent magnet magnetic field in that region, and the other branch generates an opposite electromagnetic polarity to weaken the permanent magnet magnetic field on the other side, thereby forming a radial attraction in the corresponding direction.

[0011] According to one embodiment of the permanent magnet biased radial magnetic levitation bearing of the present invention, the stator core and the rotor core are both made of stacked silicon steel sheets.

[0012] According to one embodiment of the permanent magnet biased radial magnetic levitation bearing of the present invention, the stator and the rotor have a uniform radial air gap along the circumferential direction.

[0013] According to one embodiment of the permanent magnet biased radial magnetic levitation bearing of the present invention, the magnetic poles of the permanent magnets are arranged as N, N, S, S, N, N, S, S along the circumferential direction of the stator.

[0014] According to one embodiment of the permanent magnet biased radial magnetic levitation bearing of the present invention, the stator teeth and their end permanent magnets constitute a pair of magnetic pole action regions, and each magnetic pole action region and its oppositely arranged magnetic pole action region together form a pair of attraction forces with a radial degree of freedom.

[0015] According to one embodiment of the permanent magnet biased radial magnetic levitation bearing of the present invention, two branches of the same degree of freedom generate electromagnetic fields in the same direction and opposite direction to the permanent magnet bias field respectively under the drive of the power amplifier, so that the permanent magnetic field of one branch is enhanced and the permanent magnetic field of the other branch is weakened, thereby forming a differential magnetic field to realize the bidirectional control force of the degree of freedom.

[0016] This invention achieves stable rotor levitation by controlling the magnetization and demagnetization of the magnets through the control coil and by biasing the permanent magnets. This significantly reduces the number of power amplifiers required. Attached Figure Description

[0017] Figure 1 The diagram shown is of an existing radial magnetic levitation bearing structure.

[0018] Figure 2 The diagram shown is a control block diagram of an existing system using radial magnetic levitation bearings.

[0019] Figure 3 The diagram shown is a schematic of the permanent magnet biased radial magnetic levitation bearing of the present invention.

[0020] Figure 4 The diagram shown is a schematic of the control winding wiring.

[0021] Figure 5 This is a block diagram of the y-axis control of the permanent magnet biased radial magnetic levitation bearing of the present invention. Detailed Implementation

[0022] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0023] Figure 3 The diagram shown is a schematic of the permanent magnet biased radial magnetic levitation bearing of the present invention. Figure 3As shown, the radial magnetic levitation bearing of the present invention includes a stator, a rotor, and a matching control and detection circuit. The stator includes a stator core 11, magnets 12, a control winding 13, and an insulation structure. The rotor includes a rotor core 14, which is mounted on a rotating shaft and maintains a radially uniform air gap with the stator. The stator core 11 is arranged in a ring, and several radial teeth are machined at equal intervals on the inner circumference of the ring core. Each tooth root has a coil slot for mounting the control winding 13, and the outer side of the tooth serves as the mounting surface for the magnets 12. The magnets 12 are mounted on this mounting surface and maintain a radial air gap with the rotor core 14. The rotor core 14 is machined into a cylindrical or near-cylindrical structure and fitted onto the rotating shaft. The outer circumference of the stator can be connected to the outer casing through a base or support structure to ensure stable air gap dimensions and overall assembly positioning. In this embodiment, the stator has eight teeth around its circumference, with each tooth evenly spaced and extending radially toward the rotor.

[0024] like Figure 3 As shown, in this embodiment, a magnet 12 is provided at the inner end of each tooth. The magnetic poles of the magnet 12 are arranged sequentially as N, N, S, S, N, N, S, S along the circumference of the stator. This generates multiple magnetic pole loops. The magnetic pole loops interact with radially opposite opposite poles to generate a control magnetic field with one degree of freedom. Under the combined action of two opposing magnetic poles, the rotor shaft of the motor is constrained along the x-axis and y-axis.

[0025] Figure 4 The diagram shown is a schematic of the control winding wiring. Figure 3 as well as Figure 4As shown, each of the eight stator teeth is wound with an independent coil. These independent coils are wound according to the dimensions of the stator core teeth and nested at the bottom of each tooth. Of the four independent coils controlling the Y-axis degree of freedom of winding 13, coil 1 and coil 5 are connected in series, and coil 8 and coil 4 are connected in series, then the two series branches are connected in parallel. When a positive current I+ is applied to coil 1, the magnetic poles generated by coils 1 and 8 in the positive Y-axis direction are exactly in the same direction as the magnetic poles of magnet 12. Correspondingly, the magnetic poles generated by stator coils 4 and 5 in the negative Y-axis direction are exactly opposite to the magnetic poles of magnet 12. At this time, the magnetic field in the positive Y-axis direction is enhanced, and the magnetic field in the negative Y-axis direction is weakened, thus the stator core 11 can generate an attractive force on the rotor core 14 in the positive Y-axis direction. Similarly, the X-axis is controlled by coils 2 and 6 connected in series, and coils 3 and 7 connected in series, then connected in parallel. For radial control in the X-axis direction, coils 2 and 6 are connected in series to form the first branch, and coils 3 and 7 are connected in series to form the second branch. The two branches are then connected in parallel and driven by the same power amplifier, thus forming a complete control winding 13 structure for the X-axis degree of freedom. When a positive current I+ is applied to the terminal of coil 2, the current flows sequentially through coils 2 and 6, and simultaneously through coils 3 and 7, interacting with the permanent magnet biasing magnets 12 mounted on their respective teeth. In this embodiment, the four coils in the same degree of freedom form two controlled branches through series and parallel connections. The current direction of the two branches is automatically distinguished by the power amplifier (I... + Or I - Thus, differential magnetic field adjustment is achieved based on the permanent magnet bias field.

[0026] Figure 5 This is a block diagram of the y-axis control of the permanent magnet biased radial magnetic levitation bearing of the present invention, as shown below. Figures 3 to 5 As shown, this embodiment employs a closed-loop control structure. A displacement sensor detects the rotor's displacement in the Y-axis direction, inputs the detected signal to a comparator, and compares it with a center reference value to obtain a deviation signal. This deviation signal is then sent to the controller, which outputs a current control command based on the control law. The power amplifier converts this command into a corresponding current and applies it to the circuit. Figure 4 The control winding 13 circuit is used in the control winding 13 circuit. Since the control winding 13 structure of this degree of freedom adopts a two-branch parallel connection and a set of power amplifier driving mode, the controller only needs to output a single current command to realize the differential magnetic field control of this degree of freedom.

[0027] like Figures 3 to 5 As shown, the working process of the present invention is briefly described. Based on the permanent magnet bias magnetic field, when the controller applies I to the Y-axis control winding 13... + When the directional current is applied, the direction of the electromagnetic field generated in coils 1 and 5 is consistent with the direction of the magnet 12 on the corresponding teeth, thus enhancing the permanent magnet bias field in that region. And I +In the series-parallel structure, the current causes the electromagnetic field direction within coils 8 and 4 to be opposite to the magnetization direction of magnet 12, thus weakening the permanent magnet bias flux intensity in that region. At this time, I + Current in Figure 4 The structure shown effectively magnetizes coils 1 and 5 and demagnetizes coils 8 and 4, thereby creating a radial magnetic force on the rotor in the Y-axis direction. When I is applied... - When the directional current is applied, coils 8 and 4 are magnetized, while coils 1 and 5 are demagnetized, reversing the direction of the radial magnetic force. This differential magnetic field adjustment method allows for bidirectional force output from a single degree of freedom to be achieved with only one current amplifier, significantly simplifying the control system configuration.

[0028] like Figures 3 to 5 As shown, when the controller applies I to the X-axis control winding 13 + When the directional current is applied, the direction of the electromagnetic field generated in coils 2 and 6 is consistent with the magnetization direction of the magnet 12 on the corresponding teeth, thus forming a magnetization effect in the tooth area corresponding to the positive X-axis direction, which enhances the permanent magnet bias magnetic field in that direction; at the same time, due to the current direction characteristics of the series-parallel structure, I + The current causes the electromagnetic field in coils 3 and 7 to be opposite to the magnetization direction of the tooth-end magnet 12, thus creating a demagnetizing effect in the tooth region corresponding to the negative X-axis direction, weakening the permanent magnet bias magnetic field in that direction. Therefore, in I + Under the influence of current, coils 2 and 6 achieve magnetization and coils 3 and 7 achieve demagnetization, thereby causing the stator core 11 to generate an attractive force on the rotor core 14 in the positive X-axis direction, achieving radial control in the positive X-axis direction. When I is applied... - When the directional current is applied, coils 3 and 7 become magnetized, while coils 2 and 6 become demagnetized, reversing the direction of the radial magnetic force and thus achieving control in the negative X-axis direction. Through this differential magnetic field adjustment method, the X-axis degree of freedom also requires only one current amplifier to achieve bidirectional force output, significantly reducing the number of power amplifiers in the system and simplifying the control structure.

[0029] like Figure 4 As shown, the stator core 11 and the rotor core 14 can be made of stacked silicon steel sheets.

[0030] In this embodiment, during operation, the stator teeth magnets form a basic permanent magnet bias magnetic field. Each pair of adjacent teeth with magnets aligned in direction constitutes a magnetic pole region, structurally creating attractive pairs along the X or Y axes. When the rotor deviates, the permanent magnet attraction weakens on one side of the deviated direction, while the attraction strengthens on the other side. At this point, the displacement sensor feeds back the deviance to the controller. The controller calculates the compensation current and outputs I through a power amplifier. + Or I - Current is used to magnetize two coils and demagnetize the other two coils, through which... Figure 4 The series-parallel connection structure enables differential power output, thereby pulling the rotor back to the center. This process is repeated continuously, keeping the rotor suspended and stable in two radial degrees of freedom.

[0031] This invention achieves stable rotor levitation by controlling the magnetization and demagnetization of the magnets through the control coil and by biasing the permanent magnets. This significantly reduces the number of power amplifiers required.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A permanent magnet biased radial magnetic levitation bearing, characterized in that, include: Stator, rotor, and control windings; The stator includes a stator core arranged in a ring, and the inner circumference of the stator core is provided with a number of radially extending teeth, and a permanent magnet is provided at the end of each tooth. Several coils are arranged one-to-one on each tooth; For each radial degree of freedom of the rotor, several coils are selected from the coil unit and connected in series and parallel to form a control winding; The controller is used to apply positive or negative control signals to the control winding based on the rotor's offset in the corresponding radial degree of freedom. The power amplifier amplifies the positive or negative control signal of the controller, thereby generating a controllable bidirectional radial suction force in the corresponding single radial degree of freedom direction, so that the rotor is kept in the central suspended position. The displacement sensor is used to detect the rotor's offset in the corresponding radial degree of freedom in real time, and the controller outputs control current commands based on the offset.

2. The permanent magnet biased radial magnetic levitation bearing according to claim 1, characterized in that, The permanent magnet is made of magnetic steel.

3. The permanent magnet biased radial magnetic levitation bearing according to claim 1 or 2, characterized in that, An even number of radially extending teeth are arranged periodically with two adjacent N poles followed by two adjacent S poles to form a magnetic pole loop. The magnetic pole loop interacts with radially opposite opposite poles to generate a control magnetic field with one degree of freedom. Under the combined action of the two opposing magnetic poles, the rotor shaft of the motor is constrained on the x-axis and y-axis.

4. The permanent magnet biased radial magnetic levitation bearing according to claim 1 or 2, characterized in that, The coils that constitute the same degree of freedom control winding are divided into two branches. Each branch consists of at least two coils connected in series. The two branches are then connected in parallel and driven by a power amplifier.

5. The permanent magnet biased radial magnetic levitation bearing according to claim 4, characterized in that, When the power amplifier applies a positive current to the corresponding control winding, the coil in one branch generates an electromagnetic polarity consistent with the direction of the corresponding magnet to enhance the permanent magnet field in that area, while the other branch generates an opposite electromagnetic polarity to weaken the permanent magnet field on the other side, thereby forming a radial attraction in the corresponding direction.

6. The permanent magnet biased radial magnetic levitation bearing according to claim 1, characterized in that, Both the stator core and the rotor core are made of stacked silicon steel sheets.

7. The permanent magnet biased radial magnetic levitation bearing according to claim 1, characterized in that, There is a uniform radial air gap between the stator and the rotor along the circumferential direction.

8. The permanent magnet biased radial magnetic levitation bearing according to claim 1, characterized in that, The permanent magnets are arranged with the following magnetic poles along the circumference of the stator: N, N, S, S, N, N, S, S.

9. The permanent magnet biased radial magnetic levitation bearing according to claim 1, characterized in that, The stator teeth and their end permanent magnets form a pair of magnetic pole action regions. Each magnetic pole action region and its opposite magnetic pole action region together form a pair of attraction forces with a radial degree of freedom.

10. The permanent magnet biased radial magnetic levitation bearing according to claim 1, characterized in that, Two branches of the same degree of freedom generate electromagnetic fields in the same direction and opposite direction to the permanent magnet bias field, respectively, driven by the power amplifier. This strengthens the permanent magnetic field of one branch and weakens the permanent magnetic field of the other branch, thereby forming a differential magnetic field to achieve bidirectional control force for that degree of freedom.

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