A high-efficiency permanent magnet motor based on an electrically controllable and adjustable magnetic circuit.

Abstract

This invention discloses a high-efficiency permanent magnet motor based on an electrically controllable and adjustable magnetic circuit. It consists of a rotor, a stator, and an electrically controlled magnetic concentrator. The electrically controlled magnetic concentrator comprises three iron core blocks and a magnetic adjustment coil. The magnetic adjustment coil passes through the gap between adjacent iron core blocks and is wound around the middle iron core block. When a direct current is applied to the magnetic adjustment coil integrated within the electrically controlled magnetic concentrator, partial magnetic saturation occurs in the magnetic concentrator. This creates a permeability difference between the electrically controlled magnetic concentrator and the connected stator teeth. Based on the principle of minimum reluctance, the main magnetic path radially shifts towards the center of the stator teeth, thereby concentrating the main magnetic flux and reducing leakage flux, thus improving motor efficiency. This invention utilizes a small magnetic adjustment current to achieve flexible adjustment of the magnetic flux, concentrating the magnetic flux and effectively reducing leakage flux. It features high permanent magnet utilization, large output torque, and high efficiency, making it suitable for applications requiring high motor efficiency, such as electric vehicles and industrial robot joint drives.

Description

Technical Field

[0001] This invention belongs to the field of motor design and manufacturing, and specifically relates to a high-efficiency permanent magnet motor with a flux-concentrating magnetic circuit that can be electrically controlled and adjusted. Background Technology

[0002] With the improvement of permanent magnet material performance and the reduction of cost, permanent magnet motors, due to their advantages such as simple structure, high power density, high torque density, and strong overload capacity, are widely used in fields such as intelligent manufacturing, military aerospace, and electric vehicles. In recent years, more and more companies have begun to enter the electric vehicle field.

[0003] Based on the installation method of permanent magnets, permanent magnet motors can be mainly divided into surface-mounted and built-in types. Among them, the magnet-concentrating permanent magnet motor, as a special type of built-in permanent magnet motor, achieves the concentration of magnetic flux through permanent magnets arranged alternately along the circumferential direction between the rotor cores, thereby increasing the air gap magnetic flux density and motor torque density, and thus has attracted widespread attention from scholars at home and abroad.

[0004] Researchers in the field of electrical engineering investigated the performance characteristics of a flux-fed permanent magnet motor (CFPM) and a traditional built-in permanent magnet motor using a multi-objective optimization design method combining experimental design techniques and differential evolution algorithms. They also compared the performance of corresponding models using different permanent magnet materials. The literature validates the advantages of the flux-fed structure by comparing the performance differences of this model with other built-in permanent magnet motors. Through the same optimization process, the results show that the flux-fed CFPM motor using ferrite can achieve efficiencies comparable to or even higher than those of neodymium iron boron (NdFeB) motors, while reducing motor costs by approximately 40%, demonstrating the advantages of flux-fed CFPM motors in low-cost, high-performance motor design.

[0005] In addition, other motor researchers studied a fractional-slot concentrated winding permanent magnet synchronous motor. By comparing the performance differences with different pole-slot combinations, they analyzed the torque performance and vibration noise of the motor with eight different pole-slot combinations. The results show that the motor has lower torque density when the number of rotor poles is smaller, and the motor with better periodicity has better vibration and noise performance. Among them, the 12-slot 14-pole motor combines the characteristics of maximum torque density, lowest cost, and best vibration and noise performance, representing an ideal pole-slot combination scheme for this fractional-slot concentrated winding permanent magnet synchronous motor.

[0006] However, due to the inherent limitations of permanent magnet materials, traditional permanent magnet motors have many drawbacks. Their permanent magnets often use rare-earth neodymium iron boron (NdFeB), which cannot alter the magnetic field, and the air gap magnetic field cannot be adjusted. This results in a limited speed range during motoring, difficulty in adjusting output characteristics during power generation, and challenges in demagnetizing during malfunctions. Therefore, achieving adjustable air gap magnetic field in permanent magnet motors has always been a research hotspot in the field of motors. Summary of the Invention

[0007] To address the aforementioned problems, this invention discloses a high-efficiency permanent magnet motor based on an electrically controllable and adjustable magnetic circuit. It utilizes a small adjustment current to achieve flexible adjustment of the magnetic flux, thereby focusing the magnetic flux and effectively reducing leakage flux. It features high permanent magnet utilization, large output torque, and high efficiency.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A high-efficiency permanent magnet motor based on an electrically controllable and adjustable magnetic circuit includes a rotor, a stator, and an electrically controlled magnetic focusing block structure. The rotor includes a shaft, a rotor core, and permanent magnets. The stator includes a stator core, stator teeth, stator tooth shoes, and an armature winding. The electrically controlled magnetic focusing block includes a core block and a magnetic adjustment coil. The electrically controlled magnetic focusing block is positioned at the stator slot between two adjacent stator tooth shoes.

[0010] Furthermore, the electrically controlled magnetic block structure consists of three iron core blocks and a magnetic adjustment coil. The magnetic adjustment coil passes through two adjacent iron core blocks and is wound around the middle iron core block. The materials of the three iron core blocks are consistent with the stator core material. When a direct current is applied to the magnetic adjustment coil, whether the iron core blocks are saturated is determined by the amplitude of the applied direct current.

[0011] Furthermore, the electrically controlled magnetic flux-concentrating block structure achieves the effect of concentrating magnetic flux and reducing leakage magnetic flux by passing a direct current through the magnetic adjustment coil, which reduces the permeability of the iron core block and creates a difference with the permeability of the connected stator teeth, thereby changing the magnetic circuit structure.

[0012] Furthermore, in the electrically controlled magnetic block structure, the iron core block between the stator teeth fills the original gaps. In the unsaturated state, the iron core block plays a magnetic guiding role and can reduce the disturbance to the air gap magnetic flux density.

[0013] Furthermore, in the electrically controlled magnetic block structure, a sufficiently large DC current is passed through the magnetic adjustment coil, so that all three iron core blocks are in a saturated state. The function of the iron core blocks changes from magnetic conduction to magnetic resistance. The decrease in magnetic flux density leads to a decrease in back electromotive force, which in turn increases the motor speed.

[0014] Furthermore, in the electrically controlled magnetic block structure, the iron core blocks are radially stacked, the silicon steel sheet material inside the stack is the same as that of the stator core, and the three iron core blocks are arranged at equal intervals.

[0015] Furthermore, the magnetizing coil in the electrically controlled magnetizing block structure can be replaced by the armature coil in the armature winding.

[0016] Furthermore, the electrically controlled magnetic block structure can exist in both permanent magnet synchronous motors and asynchronous motors. In permanent magnet synchronous motors, the electrically controlled magnetic block is placed on the stator; in asynchronous motors, the electrically controlled magnetic block can be placed on the rotor or the stator.

[0017] Furthermore, the iron core block and adjacent stator teeth in the electrically controlled magnetic block structure can use different magnetic conductive materials and different lamination directions.

[0018] Furthermore, the maximum number of iron core blocks distributed in the electrically controlled magnetic block near the air gap is 5, and the minimum number is 1, to ensure the magnetic resistance / magnetic permeability when there is / is no DC current in the magnetic adjustment coil.

[0019] Furthermore, the high-efficiency permanent magnet motor with concentrated flux adopts fractional-slot concentrated windings.

[0020] The beneficial effects of this invention are:

[0021] (1) High flexibility. When no DC power is applied, the iron core block, as the magnetic conductor, fills the gap between the original stator teeth, which can reduce the disturbance to the air gap magnetic flux density. When DC power is applied and the iron core block placed between the stator teeth is saturated, the iron core block is equivalent to air, the magnetic resistance increases greatly, the back electromotive force of the motor decreases, and the speed increases.

[0022] (2) High efficiency. The main correlation between the efficiency of this motor and the structure of the electronically controlled magnetic flux concentrator is that: when DC current is applied to the magnetic adjustment coil, the permeability of the iron core block between the stator teeth decreases, while the permeability of the stator tooth shoe remains unchanged. This creates a permeability difference. The larger the difference, the stronger the magnetic flux concentrator effect, and the higher the motor efficiency. This difference is determined by the amplitude of the DC current applied to the magnetic adjustment coil. Applying a sufficiently large DC current can both saturate the iron core block between the stator teeth and improve the motor efficiency.

[0023] (3) High permanent magnet utilization and large output torque. The electronically controlled magnetic block structure can use the principle of magnetic saturation to create a difference in magnetic permeability between this part and the part connected to it, optimize the motor magnetic circuit, achieve the effect of focusing magnetic flux and reducing leakage magnetic flux, so that the permanent magnet utilization of the motor is high and the torque output capability is strong. Attached Figure Description

[0024] Figure 1 This is a schematic cross-sectional view of a high-efficiency permanent magnet motor based on an electrically controllable and adjustable magnetic circuit along its axis, provided in part of an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the radial cross-sectional structure of a high-efficiency permanent magnet motor based on an electrically controllable and adjustable magnetic circuit, provided in part of an embodiment of the present invention.

[0026] Figure 3 This is a three-dimensional structural diagram of the stator and electrically controlled magnetic focusing block in a high-efficiency permanent magnet motor based on an electrically controllable and adjustable magnetic circuit, provided in part of the embodiments of the present invention.

[0027] In the diagram: 1-rotor, 101-shaft, 102-rotor core, 103-permanent magnet pole, 2-stator, 201-stator core, 202-stator teeth, 203-stator tooth shoe, 204-armature winding, 3-electrically controlled magnetic block, 301-core block, 302-magnetic adjustment coil. Implementation

[0028] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] like Figure 1 and Figure 2 As shown, the present invention discloses a high-efficiency permanent magnet motor based on an electrically controllable and adjustable magnetic circuit, comprising: a rotor 1, a stator 2, and an electrically controlled magnetic focusing block 3, wherein the rotor 1 includes a shaft 101, a rotor core 102, and permanent magnet poles 103; the stator 2 includes a stator core 201, stator teeth 202, stator tooth shoes 203, and an armature winding 204; and the electrically controlled magnetic focusing block 3 includes a core block 301 and a magnetic adjustment coil 302.

[0030] like Figure 1 and Figure 2 As shown, this invention addresses the high-efficiency magnetic adjustment requirements of electric vehicle motors by developing a permanent magnet synchronous motor with high efficiency, high permanent magnet utilization, and large output torque. While traditional field weakening speed-enhancing methods for motors do not alter the motor's structure, this invention increases the spacing between stator gear shoes 203 and embeds electrically controlled magnetic flux-forming blocks 3 within them. When field weakening speed enhancement is not required, no current flows through the electrically controlled magnetic flux-forming blocks 3 embedded in the stator gear shoes 203. In this case, the blocks fill the gaps between the stator gear shoes 203, effectively reducing air gap magnetic flux density distortion caused by the larger stator gear shoe spacing. As the motor speed increases, current flows through the electrically controlled magnetic flux-forming blocks 3. As the current increases, the blocks approach magnetic saturation, reducing the back electromotive force in the armature winding. Increasing the armature winding current at this point increases the motor torque, and the decrease in back electromotive force prevents a sharp increase in motor power caused by an increase in armature current. On the other hand, due to the controllability of the current fed into the controllable magnetic block 3, the magnetic resistance of the electronically controlled magnetic block 3 can be flexibly adjusted according to the motor speed to achieve targeted field weakening and speed expansion of the motor.

[0031] like Figure 1 and Figure 2As shown, the stator core and rotor core are made of silicon steel laminations or other magnetically conductive structures, similar to the manufacturing process of ordinary motors. The stator core is made by stamping silicon steel sheets into fan-shaped laminations and stacking them on positioning ribs. The positioning ribs are welded to the frame ring plate through support plates, and the core is pressed into a whole by upper and lower toothed pressure plates and tension bolts. The rotor core is made of silicon steel sheets stamped into a ring shape and directly mounted on the motor shaft.

[0032] like Figure 2 and Figure 3 As shown, in this example, the electrically controlled magnetizing block 3 consists of an iron core block 301 and a magnetizing coil 302. The iron core block 301 is composed of three radially stacked silicon steel sheets of equal spacing and thickness. Its radial length, arc, and adjacent spacing are designed according to the actual motor parameters. The magnetizing coil 302 can use the same parameters as the armature coil and is wound around the middle iron core block through the gap between two adjacent iron core blocks.

[0033] like Figure 3 As shown, the thickness and spacing of adjacent stator teeth of the electrically controllable magnetic circuit high-efficiency permanent magnet motor are greater than those of the traditional permanent magnet motor. This is because the stator teeth 203 need to be embedded with a certain thickness into the electrically controllable magnetic block 3. In motor design, the stator tooth spacing is related to the magnitude of the back electromotive force in the motor. A larger stator tooth spacing will reduce the back electromotive force of the motor.

[0034] like Figure 3 As shown, the iron core block 301 in the electrically controlled magnetic block 3 is composed of silicon steel sheets stacked radially, and the adjacent stator 2 is composed of silicon steel sheets stacked axially.

[0035] like Figure 2 and Figure 3 As shown, the three radially stacked silicon steel sheets in the iron core block 301 are not limited to equal spacing and thickness, and can be arbitrarily changed according to the actual electromagnetic performance of the motor.

[0036] like Figure 2 and Figure 3 As shown, the iron core block 301 is tightly embedded between the stator teeth 202. When the motor is unloaded, the iron core block fills the air gap between the stator teeth, reducing the harmonic distortion in the air gap magnetic field, and the armature winding has a high sinusoidal no-load back electromotive force waveform.

[0037] like Figure 3 As shown, the electrically controlled magnetic block 3 contains 3 iron core blocks 301. The maximum number of iron core blocks 301 is 5 and the minimum number is 1, in order to ensure the magnetic resistance / magnetic permeability of the iron core blocks 301 when there is / is no DC current in the magnetic adjustment coil 302.

[0038] like Figure 3As shown, the core block 301 in the electrically controlled magnetic block 3 is composed of silicon steel sheets radially stacked. In this embodiment of the invention, the core block material is consistent with the stator core material, but in the design, the motor performance can be optimized by using different magnetic materials.

[0039] like Figure 3 As shown, this invention applies the function of electrically controlled magnetic focusing block 3 to concentrate the main magnetic flux and reduce leakage flux in a permanent magnet synchronous motor. Similarly, an electrically controlled magnetic focusing block 3 can also be added to an asynchronous motor. The electrically controlled magnetic focusing block 3 is placed on the rotor or stator of the asynchronous motor, and the magnetic flux generated by the windings on the rotor or stator is concentrated and leakage flux is reduced by the electrically controlled magnetic focusing block 3.

[0040] like Figure 2 As shown, the protruding auxiliary tooth portion in the stator tooth shoe 203 can be removed. After removal, the corresponding missing portion is filled by the electrically controlled magnetic block. At this time, the length of the electrically controlled magnetic block increases and its thickness can also be adjusted within the range of stator tooth length. Accordingly, when a sufficient DC current is applied to saturate the longer and thicker electrically controlled magnetic block, the magnetic resistance in the motor will become larger, the back electromotive force will be lower, and the motor speed will be faster.

[0041] like Figure 2 As shown, the three iron core blocks 302 in the electrically controlled magnetic block 3 are assembled by axial insertion. The iron core blocks must fit sufficiently with the stator tooth shoe 203 to ensure the stability of the iron core blocks between the stator teeth. It is necessary to keep the distance between the three iron core blocks consistent. The magnetic adjustment coil 301 is evenly wound on the middle iron core block.

[0042] like Figure 2 As shown, the high-efficiency permanent magnet motor based on an electrically controllable adjustable magnetic circuit has two operating states, which are determined by the energization of the magnetic adjustment coil 302.

[0043] like Figure 2 As shown, when the magnetic adjustment coil 302 is not energized, the electrically controlled magnetic block 3, as part of the stator 2, fills the gap between the stator teeth and reduces its disturbance to the air gap magnetic flux density.

[0044] When current flows through the field-adjusting coil 302, a magnetic field is generated. Magnetic lines of force emanate from the middle iron core block 301, splitting into two parts that pass through the upper and lower iron core blocks respectively and return to the middle iron core block. At this time, the permeability of the electrically controlled magnetic focusing block 3 decreases, and the radial offset of the main magnetic path within the motor near the air gap from the center of the stator gear shoe 202 achieves the magnetic flux focusing effect and reduces leakage flux at the stator gear shoe. The resulting permeability difference is determined by the amplitude of the DC current within the field-adjusting coil 302; the larger the difference, the stronger the magnetic flux focusing effect and the higher the motor efficiency.

[0045] When current is applied to the magnetic adjustment coil 302, the magnetic lines of force are emitted from the middle part of the iron core block and dispersed into the upper and lower iron core blocks before returning to the middle iron core block. In order to reduce the difference in magnetic saturation intensity in the iron core block 3, the thickness of the middle iron core block is designed to be slightly larger than that of the upper and lower iron core blocks.

[0046] like Figure 3 As shown, the electrically controlled magnetic block 3 can be made of silicon steel sheet or ferrite material, and is processed by sheet stacking or casting. When ferrite material is used, the electrically controlled magnetic block and stator teeth form an alternating pole structure when no DC current is applied, increasing the motor torque. At this time, when sufficient DC current is applied, although the electrically controlled magnetic block cannot be fully saturated, it can still increase the motor speed.

[0047] like Figure 2 As shown, this invention is an improvement on the basis of a permanent magnet synchronous motor, wherein the number of pole pairs of the armature winding on the stator is consistent with the number of pole pairs of the permanent magnet on the rotor.

[0048] like Figure 2 As shown, the rotor adopts an alternating N / S pole structure. Similarly, an alternating pole structure can also be used, utilizing the characteristic of a magnetic core that can converge magnetic lines of force to form magnetic poles. This allows for the replacement of some permanent magnet poles with iron core poles, creating a hybrid magnetic pole structure. The N pole uses neodymium iron boron material, while the S pole is entirely replaced by an iron core. By appropriately increasing the pole arc coefficient and magnet thickness of the permanent magnet poles, the motor using an alternating pole excitation structure can improve the utilization rate of permanent magnets, thereby increasing the motor's torque density and output capacity, and effectively reducing motor production costs.

[0049] like Figure 2 As shown, the armature winding 204 adopts a fractional-slot concentrated winding, which is wound on the stator teeth. In this embodiment, since the ends of the fractional-slot concentrated winding are shorter than those of the traditional distributed winding, the copper loss is low, which helps to reduce the temperature rise of the motor under load.

[0050] The electrically controlled magnetic block structure in the high-efficiency permanent magnet motor based on an electrically controllable adjustable magnetic circuit proposed in this example fills all the gaps between the stator teeth with the core block when no DC current is applied. However, when a sufficient DC current amplitude is applied, the core block can be treated as air, increasing the motor's magnetic reluctance, decreasing the back electromotive force, and increasing the speed. Based on this characteristic, this motor can be applied to any application requiring high starting speeds, such as electric vehicles, impact drills, and electric mixers.

[0051] When a DC current sufficient to saturate the iron core block is applied to the electrically controlled magnetic focusing block in the motor, a difference in permeability is generated between the stator gear shoe and the electrically controlled magnetic focusing block in the high-efficiency permanent magnet motor with magnetic flux focusing, thereby achieving magnetic flux focusing, reducing magnetic leakage at both ends of the stator gear shoe, and optimizing the motor magnetic circuit. As a result, the motor has high permanent magnet utilization, high torque output, and high efficiency, and is suitable for applications requiring high motor efficiency, such as electric vehicles and industrial robot joint drives.

[0052] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A high efficiency permanent magnet machine based on the principle of magnetic flux concentration by electrically controllable adjustment of the magnetic circuit, the machine comprising a rotor (1) and a stator (2), wherein The rotor (1) comprises a shaft (101), a rotor core (102), and a permanent magnet (103), and the stator (2) comprises a stator core (201), a stator tooth (202), a stator tooth shoe (203), and an armature winding (204), The electric control magnetic block (3) comprises a core block (301) and a magnetic adjusting coil (302); the core block (301) is composed of three radially arranged and stacked silicon steel sheets with equal intervals, and the magnetic adjusting coil (302) is wound on the middle core block (301) through the gap between the adjacent two core blocks; and the electric control magnetic block (3) formed by the core block (301) and the magnetic adjusting coil (302) is arranged at the slot opening between the adjacent two stator tooth shoes (203). The electric control magnetic block (3) and the permanent magnet, air and core connected therewith form a magnetic permeability difference to change the magnetic circuit structure, thereby concentrating the magnetic flux and reducing the leakage magnetic flux. The core of the electric control magnetic block (3) and the adjacent stator tooth shoe (203) is composed of two magnetic conductive materials with different magnetic conductive properties, and the lamination stacking directions of the core of the electric control magnetic block (3) and the adjacent stator tooth shoe (203) are different.

2. The high-efficiency magnetic flux concentration permanent magnet motor based on electrically controllable adjustable magnetic circuit according to claim 1, characterized in that: In the permanent magnet synchronous motor, the electric control magnetic block (3) is arranged on the stator (2); in the asynchronous motor, the electric control magnetic block (3) can be arranged on the rotor (1) or the stator (2).

3. The high-efficiency magnetic flux concentration permanent magnet motor based on electrically controllable adjustable magnetic circuit according to claim 1, characterized in that: The maximum number of core blocks in the electric control magnetic block (3) near the air gap is 5, and the minimum number is 1, so as to ensure the magnetic resistance / magnetic conductive property of the magnetic adjusting coil (302) with / without direct current.

4. The high efficiency permanent magnet machine based on the flux concentrating magnetic circuit with electrically controllable flux adjustment according to claim 1, characterized in that: The working principle is as follows: On the basis of the traditional permanent magnet synchronous motor, the distance between the stator tooth shoes (203) is increased, and the electric control magnetic block (3) is embedded therebetween; when the motor does not need to be weakly magnetized for speed expansion, the magnetic adjusting coil (302) wound on the electric control magnetic block (3) is not connected with direct current, at this time, the electric control magnetic block (3) as a core block fills the gap between the stator tooth shoes (203), which can effectively reduce the air gap magnetic flux density distortion; when the magnetic adjusting coil (302) in the electric control magnetic block (3) is connected with direct current, with the increase of the current, the magnetic saturation degree of the electric control magnetic block (3) becomes larger, the magnetic resistance becomes larger, and the back electromotive force decreases, at this time, the armature winding current is increased to improve the motor torque, and due to the decrease of the back electromotive force, the motor overload problem caused by the increase of the armature current can be avoided; on the other hand, due to the controllability of the current in the electric control magnetic block (3), the magnetic resistance of the electric control magnetic block (3) can be flexibly adjusted according to the motor speed, so as to realize the targeted weak magnetic expansion of the motor; The electric control adjustment of the magnetic permeability distribution in the electric control magnetic block (3) is realized by adjusting the direct current amplitude of the magnetic adjusting coil, the magnetic permeability difference between the electric control magnetic block (3) and the stator tooth shoe (203) connected therewith changes the main magnetic flux path to the center of the stator tooth (202), concentrates the main magnetic flux and reduces the leakage magnetic flux, and improves the motor efficiency.

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