A multi-magnetic-source permanent magnet motor and an iron loss suppression method based on double magnetic pole domain cooperation

Abstract

This invention relates to a multi-magnetic-source permanent magnet motor and a method for suppressing iron loss based on dual-magnetic-pole domain collaboration, belonging to the field of motor and control technology. It includes a stator and a rotor. The rotor has 2p magnetic pole units evenly distributed circumferentially. Each magnetic pole unit is divided into a first magnetic pole domain and a second magnetic pole domain along the radial direction of the rotor, with a dividing radius as the boundary. In the first magnetic pole domain, arc-shaped rare-earth permanent magnet groups and rectangular non-rare-earth permanent magnets are arranged in parallel. In the second magnetic pole domain, two symmetrically arranged arc-shaped non-rare-earth permanent magnets are provided, forming a series magnetic circuit with some of the arc-shaped rare-earth permanent magnets in the first magnetic pole domain. The rotor employs a radial dual-magnetic-pole domain functional zoning design to accurately cancel the high-order harmonic components of the main magnetic flux, cutting off the main cause of core loss at its source. The parameters of the dual-magnetic-pole magnets are accurately matched through equivalent magnetic circuit modeling, and the harmonic suppression and iron loss suppression effects are verified by finite element simulation, avoiding the inefficiency of repeated trial and error in traditional designs.

Description

Technical Field

[0001] This invention relates to the field of motor and control technology, and in particular to the topology design of permanent magnet synchronous motors and iron core loss suppression technology, specifically to a multi-magnetic-source permanent magnet motor and an iron loss suppression method based on dual magnetic pole domain cooperation. Background Technology

[0002] In recent years, rare earth permanent magnet motors have been widely used in electric drive systems such as new energy vehicles and aerospace due to their advantages such as high power density and high torque density, becoming a core equipment to promote the upgrading of electric drive technology. In order to achieve the sustainable development of the permanent magnet motor industry, rare earth permanent magnet motors under the "hybrid permanent magnet" design concept have become a research hotspot and core direction in the field of motor design.

[0003] In existing technologies, several hybrid permanent magnet designs have been developed to reduce the amount of rare earth elements used. For example, Chinese Patent No. 202211183833.7 discloses a method that reduces the amount of rare earth permanent magnets and provides appropriate torque by alternately setting first and second magnetic poles with different amounts of magnetic material on the rotor using an asymmetric structural design. Chinese Patent No. 201711390249.8 discloses a method that increases the reluctance torque component by alternately setting reluctance poles and permanent magnet poles, effectively reducing the amount of rare earth permanent magnets while maintaining a similar output torque. However, the aforementioned asymmetric hybrid permanent magnet pole designs are prone to causing air gap magnetic flux density distortion, leading to a significant increase in the air gap harmonic content of the motor. In addition, Chinese Patent No. 201810562147.8 discloses a method of reducing the amount of rare earth permanent magnets by using a combination of rare earth and non-rare earth magnetic materials for excitation. However, due to the significant differences in magnetic properties such as magnetic resistance and magnetic energy product between the two types of magnetic materials, the air gap magnetic flux density harmonic problem is inevitably aggravated.

[0004] It should be noted that the high-order harmonic components in the main magnetic flux not only cannot be converted into effective electromagnetic torque, but also cause a significant increase in core losses when the motor is running at high speed, severely limiting the operating efficiency of the motor under high-speed conditions, making it difficult to achieve the dual goals of "cost reduction" and "efficiency improvement". Therefore, how to effectively integrate the "hybrid permanent magnet" design concept into the design of permanent magnet motors, and through topology reconstruction and parameter optimization of hybrid magnetic sources, effectively suppress air gap magnetic flux density harmonics and core losses while ensuring torque output capability and reducing the amount of rare earth permanent magnets used, and ultimately achieve cost reduction and efficiency improvement of the motor, has become a key technical problem that urgently needs to be solved in the current design field of rare earth permanent magnet drive motors. Summary of the Invention

[0005] This invention aims to address the technical pain points of existing hybrid permanent magnet motors, such as high air gap magnetic flux density harmonic content, large iron core losses, and difficulty in simultaneously reducing rare earth usage, torque output, and efficiency improvement. It provides a multi-magnetic-source permanent magnet motor and an iron loss suppression method based on dual magnetic pole domain collaboration. By dividing the rotor radial dual magnetic pole domains and constructing a composite magnetic circuit topology of heterogeneous magnetic sources, the invention accurately suppresses air gap magnetic flux density harmonics, effectively reduces iron core losses, and reduces the amount of rare earth permanent magnets used while maintaining motor output performance.

[0006] To solve the above technical problems, the present invention adopts the following technical solution: a multi-magnetic-source permanent magnet motor, including a stator and a rotor, wherein the stator is provided with an armature winding, and the rotor is uniformly distributed with 2p magnetic pole units along the circumference, where p is the number of pole pairs of the motor rotor. Each magnetic pole unit is divided into a first magnetic pole domain and a second magnetic pole domain along the radial direction of the rotor from the inside to the outside, with the boundary radius as the boundary.

[0007] Within the first magnetic pole domain, an arc-shaped rare-earth permanent magnet assembly and a rectangular non-rare-earth permanent magnet are arranged. The arc-shaped rare-earth permanent magnet assembly includes two arc-shaped rare-earth permanent magnets symmetrically embedded on both sides of the rectangular non-rare-earth permanent magnet, and the arc-shaped rare-earth permanent magnet assembly and the rectangular non-rare-earth permanent magnet form a parallel magnetic circuit.

[0008] The second magnetic pole region contains two symmetrically arranged arc-shaped non-rare earth permanent magnets, which form a series magnetic circuit with some arc-shaped rare earth permanent magnets in the first magnetic pole region to weaken the high-order harmonic components of the main magnetic flux.

[0009] Preferably, within the first magnetic pole domain: the arc-shaped rare-earth permanent magnet and the rectangular non-rare-earth permanent magnet are both magnetized along the thickness direction and in the same direction, both pointing towards or away from the rotor center; the magnetization directions of the same magnets in adjacent magnetic pole units are opposite.

[0010] Within the second magnetic pole domain: each arc-shaped non-rare earth permanent magnet in the magnetic pole unit is magnetized along the thickness direction, and the direction is consistent and all point towards or away from the rotor center; the magnetization direction of the same magnet in adjacent magnetic pole units is opposite, which is in coordination with the magnetization rule of the first magnetic pole domain.

[0011] Preferably, three parallel rotor magnetic circuits are formed between the connected magnetic pole units, including:

[0012] The first magnetic circuit consists of two rectangular non-rare earth permanent magnets in the first magnetic pole domain of adjacent magnetic pole units, serving as a supplementary path for the fundamental wave.

[0013] The second magnetic circuit is composed of the remaining arc-shaped rare-earth permanent magnets in the first magnetic pole domain that did not participate in the series magnetic circuit, and serves as the fundamental main path.

[0014] The third magnetic circuit consists of a portion of the arc-shaped rare-earth permanent magnets in the first magnetic pole region and two arc-shaped non-rare-earth permanent magnets in the second magnetic pole region, serving as a harmonic suppression path.

[0015] Preferably, a magnetic bridge is provided between the arc-shaped rare-earth permanent magnet and the rectangular non-rare-earth permanent magnet.

[0016] Preferably, a magnetic isolation groove is provided in the second magnetic pole region at the junction of the end of the arc-shaped rare earth permanent magnet and the arc-shaped non-rare earth permanent magnet, and the end of the arc-shaped rare earth permanent magnet is embedded in the magnetic isolation groove.

[0017] Preferably, the central angle corresponding to the arc length of the arc-shaped non-rare earth permanent magnet is... satisfy: .

[0018] Preferably, within the first magnetic pole domain, the remanence ratio of the arc-shaped rare-earth permanent magnet group to the rectangular non-rare-earth permanent magnet group is 2.5:1 to 3.5:1, and the volume ratio is 1:2 to 1:4.

[0019] This invention also discloses a method for suppressing iron loss based on dual magnetic pole domain cooperation, which involves performing the following steps based on a multi-magnetic-source permanent magnet motor:

[0020] S1, to determine the boundary radius to meet the constraints of the fundamental magnetic flux supply capacity and size feasibility of the first magnetic pole domain;

[0021] S2. Construct an equivalent magnetic circuit model and clarify the correspondence between the reluctance and magnetomotive force elements in the model and the magnets and magnetic branches in each magnetic pole domain; calculate the magnetomotive force and reluctance parameters of each magnet, obtain the combined magnetic flux through magnetic flux superposition and decompose it into fundamental magnetic flux and harmonic magnetic flux, optimize the magnet parameters so that the fundamental magnetic flux density meets the torque performance requirements, and at the same time control the total harmonic distortion rate within the target range.

[0022] S3. A motor simulation model is built using finite element analysis software, and the motor iron loss is calculated through transient electromagnetic field simulation:

[0023] If the iron loss value does not meet the iron loss target, adjust the size and position of the arc-shaped non-rare earth permanent magnet and re-simulate;

[0024] If the iron loss value meets the standard, then assess whether the output torque under rated operating conditions meets the target requirements:

[0025] If the output torque does not meet the target, adjust the dimensions of the arc-shaped rare-earth permanent magnet assembly and the rectangular non-rare-earth permanent magnet assembly, and then return to calculate the motor iron loss value.

[0026] Repeat the above steps until all performance metrics meet the constraints.

[0027] S4. Determine the final motor design scheme and output the corresponding parameter drawings and performance analysis report.

[0028] Preferably, in S1, the dividing radius The constraints are satisfied as follows:

[0029] ;

[0030] ;

[0031] in, The flux utilization coefficient of the first magnetic pole region. The polar arc coefficient of the first magnetic pole region. Where N is the frequency and N is the number of turns in the stator armature winding. Rated current, Let be the inner radius of the rotor's first magnetic pole region. The outer radius of the rotor's second magnetic pole domain.

[0032] Preferably, the first magnetic pole domain provides at least [amount] to the air gap. The initial fundamental air gap magnetic flux density, The supply coefficient for the fundamental magnetic flux density; For air gap magnetic flux density;

[0033] Radial thickness of the second magnetic pole domain ,in , .

[0034] Beneficial effects: (1) The present invention adopts a rotor radial dual magnetic pole domain functional partitioning design. The first magnetic pole domain focuses on the supply of fundamental magnetic flux, and the second magnetic pole domain focuses on harmonic suppression. Through the series-parallel composite magnetic circuit topology of the dual magnetic pole domain, the non-rare earth magnets in the second magnetic pole domain and some rare earth magnets in the first magnetic pole domain form a reverse magnetomotive force, which accurately cancels the high-order harmonic components of the main magnetic flux, and cuts off the main cause of core loss from the source. Compared with the traditional hybrid permanent magnet motor, the functional partitioning of the dual magnetic pole domain is clearer, the magnetic circuit coordination is more precise, the harmonic suppression is significantly more targeted and effective, and the core loss is reduced more significantly.

[0035] (2) Based on the dual magnetic pole domain topology, the first magnetic pole domain of this invention adopts a parallel configuration of "rare earth + non-rare earth" heterogeneous magnetic sources. Under the premise of ensuring the supply of fundamental magnetic flux, the amount of rare earth permanent magnets used is greatly reduced, effectively avoiding the risks of rare earth resource price fluctuations and supply chain instability. At the same time, the low cost characteristics of non-rare earth magnets further reduce the cost of motor raw materials. In addition, the core loss brought about by the synergistic harmonic suppression of the dual magnetic pole domain is significantly reduced, and the motor operating efficiency is improved simultaneously, ultimately achieving the dual goals of cost reduction and efficiency improvement of "reducing rare earth, controlling costs, and improving efficiency".

[0036] (3) Based on the principle of dual magnetic pole domain collaboration, a closed-loop design process of "parameter initialization - magnetic pole domain planning - composite magnetic circuit design - simulation verification" is constructed. The parameters of the dual magnetic pole domain magnets are accurately matched by equivalent magnetic circuit modeling. The harmonic suppression and iron loss suppression effects are verified by finite element simulation, avoiding the inefficiency of repeated trial and error in traditional design. The clear functional division of dual magnetic pole domains makes the optimization target more focused, significantly improving the efficiency of motor optimization design and the reliability of the scheme. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of the multi-magnetic-source permanent magnet motor of the present invention;

[0038] Figure 2 This is a schematic flowchart of the method of the present invention;

[0039] Figure 3 for Figure 1 A magnified view of the local structure of the rotor and a schematic diagram of the distribution of the dual magnetic pole domains and the magnetic circuit direction;

[0040] Figure 4 for Figure 3 Schematic diagram of the overall structure and magnetization method of the first magnetic pole region of the central rotor;

[0041] Figure 5 for Figure 4 Detailed structural and parameter annotation diagram of the rectangular non-rare earth permanent magnet in the first magnetic pole region of the middle section;

[0042] Figure 6 for Figure 4 Detailed structural and parameter annotation diagram of the arc-shaped rare earth permanent magnet in the first magnetic pole region of China;

[0043] Figure 7 for Figure 3 Schematic diagram of the overall structure and magnetization method of the second magnetic pole region of the central rotor;

[0044] Figure 8 for Figure 7 Detailed structural and parameter annotation diagram of the arc-shaped non-rare earth permanent magnet in the second magnetic pole region of the middle;

[0045] Figure 9 for Figure 1 A schematic diagram of the equivalent magnetic circuit and equivalent magnetomotive force under a pair of magnetic poles in the middle;

[0046] Figure 10 for Figure 1 Comparison of air gap magnetic flux density waveforms and harmonic spectra in a pair of magnetic pole regions before and after matching of the dual magnetic pole regions;

[0047] Figure 11 for Figure 1 Comparison of per-unit iron loss values ​​before and after matching of the two magnetic pole domains.

[0048] The diagram is labeled as follows: 1. Stator; 1.1. Stator yoke; 1.2. Stator teeth; 2. Armature winding; 3. Air gap; 4. Rotor; 5. First magnetic pole region magnet assembly; 6. Second magnetic pole region magnet assembly; 7. Shaft; 4.1. First magnetic pole region; 4.2. Second magnetic pole region; 5.1. Arc-shaped rare-earth permanent magnet assembly; 5.2. Rectangular non-rare-earth permanent magnet; 4.1.1. First magnetic bridge; 4.1.2. Second magnetic bridge; 5.1.1. First arc-shaped rare-earth permanent magnet; 5.1.2. Second arc-shaped rare-earth permanent magnet; 4.2.1. First magnetic isolation slot; 4.2.2. Second magnetic isolation slot; 6.1. First arc-shaped non-rare-earth permanent magnet; 6.2. Second arc-shaped non-rare-earth permanent magnet; 8.1. First magnetic circuit; 8.2. Second magnetic circuit; 8.3. Third magnetic circuit. Detailed Implementation

[0049] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0050] Example: A multi-magnetic-source permanent magnet motor mainly includes a stator 1, an armature winding 2, an air gap 3, a rotor 4, a first magnetic pole region magnet assembly 5, a second magnetic pole region magnet assembly 6, and a rotating shaft 7.

[0051] refer to Figure 1 As shown, the stator 1 is coaxially sleeved on the outside of the rotor 4, and the center position of the rotor 4 is used to install the rotating shaft 7; an air gap 3 is reserved between the inner wall of the stator 1 and the outer wall of the rotor 4. The thickness of the air gap 3 is determined by the motor power level, the selection of permanent magnet steel, the material characteristics of the stator 1 and the rotor 4, as well as the processing and assembly process parameters; the armature winding 2 is wound on the stator teeth 1.2 of the stator 1; 2p magnetic pole units are evenly distributed in the circumferential direction of the rotor 4. Each magnetic pole unit is composed of a first magnetic pole domain magnet combination 5 and a second magnetic pole domain magnet combination 6, thereby determining that the number of rotor pole pairs of this multi-magnetic source permanent magnet motor is p.

[0052] See Figure 3 Based on the number of rotor pole pairs p of this motor, Figure 3 The sector shown represents the 1 / p local structure of rotor 4, i.e., each pair of magnetic poles. The mechanical angle corresponding to this sector is... The rotor 4 is radially divided into two regions from the inside to the outside: the first magnetic pole region 4.1 (fundamental wave carrying region) and the second magnetic pole region 4.2 (harmonic suppression region); the inner radius of the first magnetic pole region 4.1 is... Outer radius is The first magnetic pole region magnet assembly 5 includes an arc-shaped rare-earth permanent magnet assembly 5.1 and a rectangular non-rare-earth permanent magnet assembly 5.2 located within the first magnetic pole region 4.1, and the arc-shaped rare-earth permanent magnet assembly 5.1 and the rectangular non-rare-earth permanent magnet assembly 5.2 form a parallel magnetic circuit; the inner radius of the second magnetic pole region 4.2 is... Outer radius is An arc-shaped non-rare earth permanent magnet assembly 6 is installed within the second magnetic pole region 4.2.

[0053] refer to Figure 4 As shown, the arc-shaped rare earth permanent magnet assembly 5.1 in the first magnetic pole domain 4.1 of the rotor includes two arc-shaped rare earth permanent magnets symmetrically embedded on both sides of the rectangular non-rare earth permanent magnet 5.2, which are defined as the first arc-shaped rare earth permanent magnet 5.1.1 and the second arc-shaped rare earth permanent magnet 5.1.2, respectively.

[0054] In one embodiment, a magnetic bridge 4.1.1 is provided between the first arc-shaped rare earth permanent magnet 5.1.1 and the rectangular non-rare earth permanent magnet 5.2, and a magnetic bridge 4.1.2 is provided between the second arc-shaped rare earth permanent magnet 5.1.2 and the rectangular non-rare earth permanent magnet 5.2; this effectively improves the mechanical strength of the rotor and adapts to the high-speed operation requirements of the motor.

[0055] In one embodiment, the material of the arc-shaped rare earth permanent magnet group 5.1 in the first magnetic pole domain 4.1 is preferably N35-N52 series neodymium iron boron magnet, and the material of the rectangular non-rare earth permanent magnet 5.2 is preferably Y30-Y40 series ferrite magnet. The remanence ratio of the two is controlled at 2.5:1 to 3.5:1, so as to ensure the fundamental magnetic flux supply capability while reducing the amount of rare earth.

[0056] In one embodiment, the volume ratio of the arc-shaped rare-earth permanent magnet group 5.1 to the rectangular non-rare-earth permanent magnet 5.2 in the first magnetic pole domain 4.1 is controlled at 1:2 to 1:4, so as to ensure a sufficient supply of fundamental magnetic flux while reducing the amount of rare earth.

[0057] See Figure 5 The distance between the near-rotating shaft 7 side and the rotor shaft center of the rectangular non-rare earth permanent magnet 5.2 is... The rectangular non-rare earth permanent magnet has a length of 5.2 mm. Width is The width dimensions of magnetic bridges 4.1.1 and 4.1.2 are identical. ;

[0058] In this embodiment, the magnetization method for the first magnetic pole domain 4.1 is designed as follows: the first arc-shaped rare earth permanent magnet 5.1.1 and the second arc-shaped rare earth permanent magnet 5.1.2 are both magnetized along their own thickness direction, with the magnetization direction being consistent and pointing towards or away from the center of the rotor 4; the rectangular non-rare earth permanent magnet 5.2 is also magnetized along its thickness direction, and its magnetization direction is the same as that of the arc-shaped rare earth permanent magnet group 5.1; in two adjacent magnetic pole units, the magnetization directions of the first arc-shaped rare earth permanent magnet 5.1.1, the second arc-shaped rare earth permanent magnet 5.1.2, and the rectangular non-rare earth permanent magnet 5.2 of the arc-shaped rare earth permanent magnet group 5.1 are all opposite to the magnetization directions of the corresponding magnets in the adjacent magnetic pole units.

[0059] See Figure 6 The distance from the center of the first arc-shaped rare-earth permanent magnet 5.1.1 and the second arc-shaped rare-earth permanent magnet 5.1.2 to the center of the rotor 4 shaft is: The two magnets have the same structural parameters, with both having an inner arc radius of [missing information]. The outer arc radius is .

[0060] See Figure 7 The arc-shaped non-rare earth permanent magnet group 6 in the second magnetic pole domain 4.2 of the rotor includes a first arc-shaped non-rare earth permanent magnet 6.1 and a second arc-shaped non-rare earth permanent magnet 6.2 arranged symmetrically. In this embodiment, the magnetization method of the second magnetic pole domain 4.2 is designed as follows: the first arc-shaped non-rare earth permanent magnet 6.1 and the second arc-shaped non-rare earth permanent magnet 6.2 are both magnetized along their own thickness direction, the magnetization direction is consistent, and they both point towards or away from the center of the rotor 4. In two adjacent magnetic pole units, the magnetization direction of the first arc-shaped non-rare earth permanent magnet 6.1 and the second arc-shaped non-rare earth permanent magnet 6.2 is opposite to the magnetization direction of the corresponding magnets in the adjacent magnetic pole units.

[0061] In one embodiment, the central angle corresponding to the arc length of the arc-shaped non-rare earth permanent magnet assembly 6 satisfy: This is to achieve targeted suppression of higher harmonics while avoiding excessive weakening of the fundamental magnetic flux.

[0062] In one embodiment, a magnetic isolation groove is provided within the second magnetic pole region 5.2 at the junction of the arc-shaped rare-earth permanent magnet end and the arc-shaped non-rare-earth permanent magnet. The end of the arc-shaped rare-earth permanent magnet is embedded in the magnetic isolation groove. (Referring to...) Figure 7As shown, magnetic isolation grooves are provided in the second magnetic pole domain 5.2 at both the first arc-shaped rare earth permanent magnet 5.1.1 and the second arc-shaped rare earth permanent magnet 5.1.2, and are respectively defined as the first magnetic isolation groove 4.2.1 and the second magnetic isolation groove 4.2.2. The magnetic isolation grooves can effectively suppress magnetic leakage of the magnets, so that the first arc-shaped rare earth permanent magnet 5.1.1 and the first arc-shaped non-rare earth permanent magnet 6.1, and the second arc-shaped rare earth permanent magnet 5.1.2 and the second arc-shaped non-rare earth permanent magnet 6.2 form a series magnetic circuit.

[0063] See Figure 8 The centers of the first arc-shaped non-rare earth permanent magnet 6.1 and the second arc-shaped non-rare earth permanent magnet 6.2 coincide with the axis of rotor 4; the structural parameters of the two magnets are identical, with the inner arc radius being... The outer arc radius is (Matching the outer radius of the second magnetic pole region 4.2 of rotor 4), the central angle corresponding to its arc length is Meanwhile, the included angle formed between the outer edge of the first arc-shaped non-rare earth permanent magnet 6.1 and the edge of the magnetic pole unit is... The distance from the bottom of the magnetic isolation slot 4.2.2 to the center of rotor 4 shaft is... The slot width meets the requirements. in, and These are the outer and inner arc radii of the first arc-shaped rare earth permanent magnet, respectively.

[0064] In this embodiment, three parallel rotor magnetic circuits are constructed based on a dual-pole domain structure. The fundamental main path and the supplementary path jointly ensure the output of the fundamental component of the main magnetic flux. Combined with the symmetrical design of the magnetic pole domains and the coordinated magnetization rules, this ensures stable motor output torque. The complementary design of the dual magnetic pole domains structurally resolves the technical contradiction that traditional harmonic suppression technology easily leads to torque attenuation, achieving no degradation in the core output performance of the motor, or a controllable degradation within an acceptable engineering range, thus ensuring the reliability of motor operation. The three parallel rotor magnetic circuits include:

[0065] The first magnetic path 8.1 consists of two rectangular non-rare earth permanent magnets 5.2 (belonging to the first magnetic pole domains 4.1 of two adjacent magnetic pole units), serving as a supplementary path for the fundamental wave;

[0066] The second magnetic circuit 8.2 is independently formed by the remaining arc-shaped rare earth permanent magnet group 5.1 in the first magnetic pole domain 4.1 that is not connected in series, and serves as the fundamental main path;

[0067] The third magnetic circuit 8.3 is formed by connecting a partially arc-shaped rare-earth permanent magnet assembly 5.1 in the first magnetic pole domain 4.1 with an arc-shaped non-rare-earth permanent magnet assembly 6.1 in the second magnetic pole domain 4.2 in series, serving as a harmonic suppression path.

[0068] This invention utilizes a radially segmented design of the rotor pole domain, dividing the entire rotor pole domain radially from the inside out into a first magnetic pole domain 4.1 and a second magnetic pole domain 4.2.

[0069] The rotor's first magnetic pole domain 4.1 adopts a parallel arrangement of non-rare earth magnets and rare earth magnets, mainly used to provide the fundamental component of the main magnetic flux and ensure the motor's torque output capability.

[0070] The rotor's second magnetic pole domain 4.2 is composed of non-rare earth magnets. By forming a series magnetic circuit with the rare earth magnets in the first magnetic pole domain, the characteristics of "high magnetic resistance and low magnetomotive force" of non-rare earth permanent magnets are utilized to specifically weaken the high-order harmonic components in the main magnetic flux.

[0071] According to motor theory, the higher harmonic components of the main magnetic flux not only fail to generate effective electromagnetic torque, but are also one of the main causes of stator core loss. Therefore, weakening these harmonic components is the key to achieving "efficiency improvement and loss reduction". Based on the differences in reluctance and magnetomotive force of different magnetic sources, this invention directionally configures multiple types of magnetic sources in the first magnetic pole domain 4.1 and the second magnetic pole domain 4.2. Through the coordinated control of the magnetic circuits of the two magnetic pole domains, the core loss is effectively reduced while maintaining or slightly decreasing the fundamental frequency performance.

[0072] This invention also discloses a method for suppressing iron loss based on dual magnetic pole domain cooperation, referring to... Figure 2 As shown: Based on the book "Lying to You," the multi-magnetic-source permanent magnet motor performs the following steps:

[0073] Step 1: Parameter and Constraint Initialization:

[0074] Set the rated parameters of the motor (including power) Rotation speed Performance targets (including iron loss target value) Torque target value This provides a benchmark and performance boundary conditions for subsequent magnetic pole domain planning, magnetic circuit design and performance verification.

[0075] Step 2: Planning of the dual magnetic pole domain structure, including:

[0076] Step 2.1: Calculation of main dimensions:

[0077] Based on the main dimension formulas for motors, the core dimension parameters of the motor are calculated and determined, as follows:

[0078] ;

[0079] in, Stator inner diameter For the effective core length, For winding factor, Here, A is the air gap magnetic field waveform coefficient, and A is the electrical load. For air gap magnetic flux density, For motor efficiency, The power factor.

[0080] Combined with air gap length The initial rotor outer diameter reference value is derived from the stator inner diameter. This benchmark value provides a constraint boundary for the overall radial dimension of the dual magnetic pole domain.

[0081] Step 2.2: Radial range division of the dual magnetic pole domain:

[0082] The rotor outer radius calculated in step 2.1 ( ) and rotor inner radius is As the radial constraint boundary, it extends radially along the rotor from the inside (away from the air gap side) to the outside (closer to the air gap side), with a dividing radius. Based on the division criteria, the rotor radial space is divided into the first magnetic pole domain 4.1 (fundamental wave carrying domain) and the second magnetic pole domain 4.2 (harmonic suppression domain). It is the shared radial boundary of the two magnetic pole domains.

[0083] Among them, the radial range of the first magnetic pole domain 4.1 is [ , [It is necessary to supply no less than] to the air gap. The initial fundamental air gap magnetic flux density, The preferred supply coefficient for the fundamental magnetic flux density is specified in this embodiment. It can be adjusted according to actual working conditions; the radial range of the second magnetic pole domain 4.2 is [ , ].

[0084] Boundary radius The following formula constraints must be met:

[0085] ;

[0086] ;

[0087] in, The flux utilization coefficient of the first magnetic pole region 4 is given. The polar arc coefficient of the first magnetic pole region. Where N is the frequency and N is the number of turns in the stator armature winding. Rated current, Let be the inner radius of the rotor's first magnetic pole region. The outer radius of the rotor's second magnetic pole domain.

[0088] Define the radial thickness of the second magnetic pole region 4.2 Its value must balance harmonic suppression effect and fundamental frequency performance maintenance, and is limited to . ,in Minimum radial thickness to meet harmonic attenuation requirements, The maximum radial thickness threshold is set to avoid excessive degradation of fundamental wave performance.

[0089] Step 3: First Magnetic Pole Domain 4.1 Determination of Heterogeneous Magnetic Source and Design of Magnetic Circuit Topology:

[0090] For the first magnetic pole region 4.1, combined with not less than To meet the magnetic flux supply requirements of the fundamental magnetic flux density in the air gap, a scheme combining rare-earth and non-rare-earth magnetic sources is adopted. The selection and core parameters of the two types of magnetic sources are determined to ensure sufficient supply of fundamental magnetic flux, while reserving adjustment space for harmonic suppression.

[0091] In this embodiment, the rare earth magnetic source is preferably neodymium iron boron magnet (grade NdFe35), and the core magnetic performance parameter is remanence B. r1 Coercivity H c1 The preferred non-rare earth magnetic source is ferrite magnet (grade Y30), with the core magnetic performance parameter being remanence B. r2 Coercivity H c2 , demagnetization curve BH.

[0092] To achieve effective superposition of the magnetic fluxes from the two types of magnetic sources, the first magnetic pole domain 4.1 adopts a parallel magnetic circuit structure, with the magnetization directions of the two types of magnetic sources remaining consistent. This parallel magnetic circuit is composed of rectangular non-rare-earth permanent magnets 5.2 and arc-shaped rare-earth permanent magnet groups 5.1. Based on the flux superposition effect of the parallel magnetic circuit, it ensures that the output magnetic flux meets the fundamental wave supply requirements, meaning that the air gap fundamental wave magnetic flux density after superposition is not less than [a certain value]. The flux utilization coefficient satisfies This ensures the maintenance of fundamental frequency performance.

[0093] Step 4: Second Magnetic Pole Domain 4.2 Magnetic Source Determination and Magnetic Circuit Design:

[0094] For the second magnetic pole region 4.2, combined with the specific subharmonic attenuation requirements, only a small non-rare earth magnetic source is configured. By constructing a composite magnetic circuit with the arc-shaped rare earth magnetic source of the first magnetic pole region, and by taking advantage of the difference in magnetic reluctance and magnetomotive force of the heterogeneous magnetic sources, the harmonic magnetic flux density can be precisely suppressed while the fundamental wave performance is maintained or slightly reduced.

[0095] In this embodiment, the non-rare-earth magnetic source for the second magnetic pole region 4.2 is preferably ferrite magnet (grade Y30), and the core magnetic performance parameter is remanence B. r2 Coercivity H c2The demagnetization curve is BH. By adjusting the size parameters and circumferential position of the small non-rare-earth magnet, and based on the difference in magnetoresistance and magnetomotive force between it and the arc-shaped rare-earth magnetic source in the first magnetic pole domain, a series-parallel composite magnetic circuit topology is designed, with the specific structure as follows:

[0096] Series magnetic branch: The small non-rare earth permanent magnet group 6.1 of the second magnetic pole domain 4.2 is connected in series with the partial arc-shaped rare earth permanent magnet group 5.1 of the first magnetic pole domain. The specific subharmonic magnetic flux is canceled by the reverse components of the magnetomotive force of the two types of magnetic sources.

[0097] Independent magnetic branch: The remaining arc-shaped rare earth permanent magnet group 5.1 in the first magnetic pole domain 4.1 constitutes an independent magnetic circuit, which provides fundamental magnetic flux to the air gap, maintains fundamental performance as much as possible, and avoids excessive degradation.

[0098] The composite magnetic circuit topology, with series magnetic branches and independent magnetic branches connected in parallel, achieves the design goal of "maintaining or slightly reducing fundamental performance and accurately suppressing harmonics" through the harmonic cancellation effect of the series magnetic circuit and the fundamental wave support effect of the independent magnetic circuit.

[0099] Step 5: Equivalent magnetic circuit model and magnet parameter design, including:

[0100] Step 5.1 Establishment of equivalent magnetic circuit model:

[0101] Based on the magnetic pole domain design scheme in steps 3 and 4, an equivalent magnetic circuit model is constructed. The model in this embodiment is shown below. Figure 9 The physical meanings of each component are as follows:

[0102] First magnetic pole region 4.1: , The magnetic reluctance and magnetomotive force of the rectangular non-rare earth permanent magnet steel 5.2 corresponding to the first magnetic pole domain; , The magnetic resistance and magnetomotive force of the arc-shaped rare earth permanent magnet 5.1 that corresponds to the small non-rare earth permanent magnet group 6.1 forming a series magnetic circuit. , The corresponding magnetic reluctance and magnetomotive force of the remaining arc-shaped rare earth permanent magnet steel 5.1.

[0103] Second magnetic pole region 4.2: , The magnetic reluctance and magnetomotive force of the small non-rare earth permanent magnet group 6.1 corresponding to the second magnetic pole domain.

[0104] Equivalent magnetic reluctance of the magnetic circuit: , The equivalent magnetic reluctances are for the series magnetic branch 8.3 and the independent magnetic branch (first magnetic branch 8.1 + second magnetic branch 8.2), respectively.

[0105] The magnetomotive force and magnetic reluctance of each magnet can be simplified and calculated based on its magnetic properties and dimensional parameters. The core relationship is as follows: Magnetomotive force In the formula, For magnetic field strength and The width in the magnetization direction; magnetic reluctance: In the formula, For vacuum permeability, The relative permeability of the magnet. It is the effective length of the magnet perpendicular to the magnetic flux path.

[0106] 5.2 Magnet parameter design:

[0107] Combined magnetic flux magnetic flux of series magnetic branches and independent parallel magnetic branch flux Superposition, i.e. .in, It is calculated from the total magnetomotive force and total magnetic reluctance of the series magnetic branches. It is the algebraic sum of each independent magnetic branch.

[0108] After being transmitted through the air gap, the combined magnetic flux is decomposed into fundamental and harmonic magnetic fluxes, which ultimately correspond directly to the air gap magnetic flux density index. The fundamental air gap magnetic flux density index satisfies... In the formula, This is the polar arc coefficient. The pole gap ensures that the fundamental wave performance remains within an acceptable range; the harmonic magnetic flux density is determined by the magnetic flux of each harmonic, and its total distortion rate needs to be controlled within the target range through magnetic circuit parameter matching to achieve the core objective of "maintaining or slightly reducing the fundamental wave performance and accurately suppressing harmonics".

[0109] Step 6: Simulation analysis of motor iron loss:

[0110] A motor simulation model for this scheme was built using finite element analysis software. Through transient electromagnetic field simulation calculations, the motor iron loss value under the current parameter combination was obtained. .

[0111] Step 7: Determine the iron loss target:

[0112] Determine iron loss value Does it meet the requirements? :

[0113] If the target is not met, it is determined that the current parameter combination has not achieved the iron loss target. The size of the arc-shaped non-rare earth permanent magnet in the second magnetic pole domain is adjusted, and the simulation is returned to step 6.

[0114] Conversely, if the current parameter combination is determined to achieve the iron loss target, proceed to step 8.

[0115] Step 8: Torque performance evaluation:

[0116] Under rated operating conditions, the actual output torque of the current motor design is obtained using finite element simulation software. ;

[0117] Step 9: Torque Target Determination

[0118] Determine the actual output torque Does it meet the requirements? :

[0119] If the requirements are not met, it is determined that the current parameter combination has not achieved the torque target. The dimensions of the arc-shaped rare-earth permanent magnet group and the rectangular non-rare-earth permanent magnet in the first magnetic pole domain are adjusted to optimize the fundamental magnetic flux supply. Then, return to step 6 and re-simulate.

[0120] Conversely, if the current parameter combination is determined to achieve the torque target and the iron loss meets the standard, proceed to step 10.

[0121] Step 10: Solution Output:

[0122] Determine the final motor design scheme and output the corresponding parameter drawings and performance analysis report.

[0123] The application also provides a specific embodiment of a dual-pole domain multi-permanent magnet motor structure obtained through the above design steps, and comprehensively analyzes the effectiveness and superiority of the method provided above; it achieves the dual effects of optimizing air gap magnetic flux density and reducing core loss. The specific performance verification results are as follows:

[0124] See Figure 10 The figure shows a comparison of the per-unit air gap magnetic flux density waveforms and their spectral analysis before and after the dual-layer magnetic pole domain matching. Before matching, the waveform represents the traditional structure without a second magnetic pole domain, retaining only the first. The figure clearly shows that after adopting the dual-polarity structure and composite magnetic circuit design of this scheme, the sinusoidal nature of the air gap magnetic flux density waveform is effectively improved. Spectral analysis reveals a significant reduction in harmonic content within the air gap magnetic flux density, with the total harmonic distortion rate decreasing from 28.72% before matching to 11.5% after matching. This fully verifies the effectiveness of this design scheme in suppressing harmonic magnetic flux density.

[0125] See Figure 11The figure shows a comparison of core losses before and after dual-layer magnetic pole domain matching. It illustrates the motor core losses before matching (a traditional structure without a second magnetic pole domain, retaining only the first) and after matching (using the dual-polarity structure and composite magnetic circuit designed in steps 3 and 4 of this scheme). All core loss results are normalized to the peak value of the waveform before matching. The normalized results show that the average core loss before matching was 0.7 pu. After the dual-layer magnetic pole domain matching design of this scheme, the average core loss decreased to 0.42 pu, demonstrating a significant reduction in core loss and verifying the practical effectiveness of this design scheme in optimizing core losses.

[0126] The embodiments of the present invention have been described in detail above with reference to the examples. However, the present invention is not limited to the above embodiments. For those skilled in the art, after learning the contents described in the present invention, several equivalent changes and substitutions can be made without departing from the principle of the present invention. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A multi-magnetic-source permanent magnet motor, comprising a stator and a rotor, wherein the stator is provided with an armature winding, characterized in that: The rotor has 2p magnetic pole units evenly distributed along the circumference, where p is the number of pole pairs of the motor rotor. Each magnetic pole unit is divided into a first magnetic pole domain and a second magnetic pole domain along the radial direction of the rotor from the inside to the outside, with the boundary radius as the boundary. Within the first magnetic pole domain, an arc-shaped rare-earth permanent magnet assembly and a rectangular non-rare-earth permanent magnet are arranged. The arc-shaped rare-earth permanent magnet assembly includes two arc-shaped rare-earth permanent magnets symmetrically embedded on both sides of the rectangular non-rare-earth permanent magnet, and the arc-shaped rare-earth permanent magnet assembly and the rectangular non-rare-earth permanent magnet form a parallel magnetic circuit. The second magnetic pole region contains two symmetrically arranged arc-shaped non-rare earth permanent magnets, which form a series magnetic circuit with some arc-shaped rare earth permanent magnets in the first magnetic pole region to weaken the high-order harmonic components of the main magnetic flux.

2. The multi-magnetic-source permanent magnet motor according to claim 1, characterized in that: Within the first magnetic pole domain: both the arc-shaped rare-earth permanent magnet and the rectangular non-rare-earth permanent magnet are magnetized along the thickness direction and in the same direction, pointing towards or away from the rotor center; the magnetization directions of the same-name magnets in adjacent magnetic pole units are opposite. Within the second magnetic pole domain: each arc-shaped non-rare earth permanent magnet in the magnetic pole unit is magnetized along the thickness direction, and the direction is consistent and all point towards or away from the rotor center; the magnetization direction of the same magnet in adjacent magnetic pole units is opposite, which is in coordination with the magnetization rule of the first magnetic pole domain.

3. A multi-magnetic-source permanent magnet motor according to claim 2, characterized in that: Three parallel rotor magnetic circuits are formed between the connected magnetic pole units, including: The first magnetic circuit consists of two rectangular non-rare earth permanent magnets in the first magnetic pole domain of adjacent magnetic pole units, serving as a supplementary path for the fundamental wave. The second magnetic circuit is composed of the remaining arc-shaped rare-earth permanent magnets in the first magnetic pole domain that did not participate in the series magnetic circuit, and serves as the fundamental main path. The third magnetic circuit consists of a portion of the arc-shaped rare-earth permanent magnets in the first magnetic pole region and two arc-shaped non-rare-earth permanent magnets in the second magnetic pole region, serving as a harmonic suppression path.

4. A multi-magnetic-source permanent magnet motor according to claim 3, characterized in that: A magnetic bridge is provided between the arc-shaped rare-earth permanent magnet and the rectangular non-rare-earth permanent magnet.

5. A multi-magnetic-source permanent magnet motor according to claim 3, characterized in that: A magnetic isolation groove is provided in the second magnetic pole region at the junction of the end of the arc-shaped rare earth permanent magnet and the arc-shaped non-rare earth permanent magnet, and the end of the arc-shaped rare earth permanent magnet is embedded in the magnetic isolation groove.

6. A multi-magnetic-source permanent magnet motor according to claim 3, characterized in that: The central angle corresponding to the arc length of the arc-shaped non-rare earth permanent magnet. satisfy: .

7. A multi-magnetic-source permanent magnet motor according to claim 3, characterized in that: Within the first magnetic pole domain, the remanence ratio of the arc-shaped rare-earth permanent magnet group to the rectangular non-rare-earth permanent magnet group is 2.5:1 to 3.5:1, and the volume ratio is 1:2 to 1:

4.

8. A method for suppressing iron loss based on dual magnetic pole domain cooperation, characterized in that: The following steps are performed based on the multi-magnetic-source permanent magnet motor according to any one of claims 1-7: S1, to determine the boundary radius to meet the constraints of the fundamental magnetic flux supply capacity and size feasibility of the first magnetic pole domain; S2. Construct an equivalent magnetic circuit model and clarify the correspondence between the reluctance and magnetomotive force elements in the model and the magnets and magnetic branches in each magnetic pole domain; calculate the magnetomotive force and reluctance parameters of each magnet, obtain the combined magnetic flux through magnetic flux superposition and decompose it into fundamental magnetic flux and harmonic magnetic flux, optimize the magnet parameters so that the fundamental magnetic flux density meets the torque performance requirements, and at the same time control the total harmonic distortion rate within the target range. S3. A motor simulation model is built using finite element analysis software, and the motor iron loss is calculated through transient electromagnetic field simulation: If the iron loss value does not meet the iron loss target, adjust the size and position of the arc-shaped non-rare earth permanent magnet and re-simulate; If the iron loss value meets the standard, then assess whether the output torque under rated operating conditions meets the target requirements: If the output torque does not meet the target, adjust the dimensions of the arc-shaped rare-earth permanent magnet assembly and the rectangular non-rare-earth permanent magnet assembly, and then return to calculate the motor iron loss value. Repeat the above steps until all performance metrics meet the constraints. S4. Determine the final motor design scheme and output the corresponding parameter drawings and performance analysis report.

9. The iron loss suppression method based on dual magnetic pole domain coordination according to claim 8, characterized in that: In S1, the boundary radius The constraints are satisfied as follows: ； ； in, The flux utilization coefficient of the first magnetic pole region is denoted as . The polar arc coefficient of the first magnetic pole region. Where N is the frequency and N is the number of turns in the stator armature winding. Rated current, Let be the inner radius of the first magnetic pole region of the rotor. The outer radius of the rotor's second magnetic pole domain.

10. The iron loss suppression method based on dual magnetic pole domain coordination according to claim 8, characterized in that: The first magnetic pole region provides at least [amount] to the air gap The initial fundamental air gap magnetic flux density, The supply coefficient for the fundamental magnetic flux density; For air gap magnetic flux density; Radial thickness of the second magnetic pole domain ,in , .

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