Dual three-phase hybrid excitation motor structure and design method thereof

Abstract

This invention discloses a dual-three-phase hybrid excitation motor structure and its design method, belonging to the field of motor technology. The main operating harmonic magnetomotive force of the motor is a high-order harmonic. The motor includes a stator and a rotor, wherein the rotor only contains salient poles composed of an iron core and has no excitation source; the stator includes a stator core, permanent magnets, and integrated windings. An expression η for the utilization rate of high-order harmonics of the magnetomotive force under permanent magnet excitation and DC current excitation is established. pm,m and η fw,n This reflects the magnitude of torque enhancement capability achieved through higher harmonic design. The goal is to maximize η. pm,m and η fw,n To optimize the objective and maximize its value, the values ​​of three design variables and the gear ratio were determined. Furthermore, using maximum torque as the optimization objective and fixed copper loss as a prerequisite, the other design variables were optimized, yielding their values ​​at maximum torque. This design method fully considers the higher-order components of the magnetomotive force, compensating for the shortcomings of motor topology design based on higher-order harmonic components of the magnetomotive force.

Description

Technical Field

[0001] This invention relates to motor technology, specifically to a dual three-phase hybrid excitation motor structure and its design method. Background Technology

[0002] Permanent magnet motors, with their high torque density, have been widely used in various fields such as home appliances, industrial automation, and electric vehicles. However, the excitation source of traditional permanent magnet motors is a permanent magnet, making the magnetic field difficult to adjust. Hybrid excitation motors combine the advantages of permanent magnet excitation and electrical excitation, retaining both flexible magnetic field adjustment capabilities and high torque characteristics.

[0003] In hybrid excitation motors, separating the DC current excitation winding and the AC current winding intensifies their competition for space. The integration of both into a single winding, known as an integrated winding, solves this space competition problem. However, most current hybrid excitation motors with low speed and high torque are based on the fundamental frequency design of the magnetomotive force (MF), failing to adequately consider the higher harmonics of the MF during the initial design phase. Higher harmonic design can increase the gear ratio amplitude, thereby improving torque output.

[0004] Chinese invention patent application CN201510474238.2 discloses a hybrid excitation motor, which places the AC current winding and DC excitation winding in the stator, and the rotor part is composed of permanent magnets and an iron core. This avoids the structural complexity of placing the windings in the rotor part and realizes a brushless structure. It enhances the adjustability of the air gap magnetic field and expands the speed range of the motor. However, the separation of the two sets of windings increases the spatial competition between the two sets of windings, further limiting the improvement of torque performance. Chinese invention patent application CN201911275711.9 discloses a hybrid excitation wound-rotor synchronous motor. The rotor iron core of this motor is provided with a set number of salient poles. Coils are wound on both sides of each salient pole to form a rotor excitation winding. Permanent magnets are installed on the surface of the geometric center line of each salient pole opposite to the direction of rotor rotation. The permanent magnets of the entire rotor are asymmetrically distributed. By effectively utilizing the DC excitation torque and permanent magnet torque, the torque output of the motor is improved. However, this motor has an excitation winding on its rotor, requiring the addition of brushes and slip rings, which increases maintenance costs and reduces the motor's lifespan. Chinese invention patent application number CN201811504299.9 discloses a hybrid excitation motor. This motor has several stator windings and a stator auxiliary winding on its stator core; the rotor core has a rotor excitation winding and permanent magnets, a rectifier diode and several permanent magnets. The rotor excitation winding is connected to the rectifier diode, and the permanent magnets are evenly distributed on both sides of the rotor excitation winding. The air gap magnetic field is adjusted by regulating the current in the stator auxiliary winding.

[0005] The above topology design is based on the fundamental component of the magnetomotive force (MTF) and does not fully consider the higher harmonic components, resulting in limited motor torque output. This invention proposes a dual-three-phase hybrid excitation motor structure and its design method. It employs an NNSS-type permanent magnet array and an SSNN-type MT generated by the distribution of DC current in the windings, thereby enhancing the amplitude of the higher harmonic MMF. The topology is not designed based on the conventional fundamental MMF, but rather on the higher harmonics of the MMF. Therefore, the main operating harmonic MMF of this motor is the higher harmonics, not the traditional fundamental MMF. The topology includes a rotor and a stator, wherein the number of stator slots is N. s Both the permanent magnet excitation source and the winding DC current excitation source are located in the stator. The air gap magnetic field can be enhanced or weakened by adjusting the magnitude and direction of the winding DC current. The rotor consists only of an iron core containing nitrogen. r With a single salient pole and no excitation source, the structure is simple and improves the reliability of motor operation. A high-order harmonic design method for pole-slot matching is derived through theoretical analysis. An expression η for the utilization rate of high-order harmonics of permanent magnet excitation and DC current excitation magnetomotive force is established. pm, m and η fw, n This reflects the magnitude of torque enhancement capability achieved through higher harmonic design. The goal is to maximize η. pm, m and η fw, n To optimize the objective, the maximum value of the objective is determined, thereby determining the values ​​of the three design variables and the gear ratio. Further, with maximum torque as the optimization objective and fixed copper loss as a prerequisite, the other design variables are optimized to obtain their values ​​at maximum torque. This allows for the design of a high-torque motor. This design method fully considers the higher-order components of the magnetomotive force, compensating for the shortcomings of motor topology design based on higher-order harmonic components of the magnetomotive force. Summary of the Invention

[0006] The purpose of this invention is to address the limitation on torque enhancement caused by the fact that most existing hybrid excitation motors are designed based on the fundamental magnetomotive force (MMF) without fully considering the higher harmonic components of the MMF. This invention proposes a dual three-phase hybrid excitation motor structure and its design method, employing an NNSS-type permanent magnet array and an SSNN-type MMF generated by the distribution of DC current in the windings, thereby enhancing the amplitude of the higher harmonic MMF. The topology is not designed based on the conventional fundamental MMF, but rather on the higher harmonics of the MMF. Therefore, the main operating harmonic MMF of this motor is the higher harmonics, rather than the traditional fundamental MMF. The topology includes a rotor and a stator, wherein the number of stator slots is N. s Both the permanent magnet excitation source and the winding DC current excitation source are located in the stator. The air gap magnetic field can be enhanced or weakened by adjusting the magnitude and direction of the winding DC current. The rotor consists only of an iron core containing nitrogen. rWith a single salient pole and no excitation source, the structure is simple and improves the reliability of motor operation. A high-order harmonic design method for pole-slot matching is derived through theoretical analysis. An expression η for the utilization rate of high-order harmonics of permanent magnet excitation and DC current excitation magnetomotive force is established. pm, m and η fw, n This reflects the magnitude of torque enhancement capability achieved through higher harmonic design. The goal is to maximize η. pm, m and η fw, n To optimize the objective, the maximum value of the objective is determined, thereby determining the values ​​of the three design variables and the gear ratio. Further, with maximum torque as the optimization objective and fixed copper loss as a prerequisite, the other design variables are optimized to obtain their values ​​at maximum torque. This allows for the design of a high-torque motor. This design method fully considers the higher-order components of the magnetomotive force, compensating for the shortcomings of motor topology design based on higher-order harmonic components of the magnetomotive force.

[0007] Specifically, the motor of the present invention is implemented by the following technical solution:

[0008] A dual-three-phase hybrid excitation motor structure is disclosed, comprising a rotor (1) and a stator (2). The rotor (1) has N... r Each salient pole (6) consists only of an iron core and has no excitation source; the stator (2) includes a stator iron core, stator teeth (3), iron poles (4), permanent magnets (5), and integrated windings (7), wherein the stator iron core is an open slot design and the number of slots in the stator (2) is N. s A winding in which both alternating current and direct current are simultaneously circulated in the phase current is called an integrated winding (7), which uses a double-layer winding, 2N s N is composed of conductors. s Each phase winding consists of N coils. s The stator consists of six coils connected in series, forming two sets of three-phase windings, i.e., double three-phase windings. The integrated winding (7) is distributed in the open slots of the stator core and wound on the stator teeth (3) using a distributed connection method. N is distributed along the circumference of the stator (2). s One permanent magnet (5) is placed on each stator tooth (3). The permanent magnet is located between two iron poles (4). The magnetization direction of the permanent magnet (5) is radial. The smallest unit of permanent magnet distribution consists of two N-pole permanent magnets and two S-pole permanent magnets, which is denoted as NNSS type permanent magnet array. The included angle between the centers of adjacent permanent magnets is 2π / N. s The stator and rotor cores are made of magnetically conductive materials such as silicon steel sheets, while the permanent magnets (5) are made of neodymium iron boron. The permanent magnets (5) are embedded in the top of the stator teeth (3), and the included angle between the centers of adjacent permanent magnets is 2π / N. s The magnetization direction of the N-pole permanent magnet (5) is defined as radial magnetization, away from the center, while the magnetization direction of the S-pole permanent magnet (5) is radial magnetization, pointing towards the center. sFive permanent magnets (5) are distributed along the circumference to form N s The main magnetic field of the / 4 pole pair.

[0009] In this method, the permanent magnet array is distributed in an NNSS pattern along the outer circumference of the stator, forming high-order harmonics with high magnetomotive force amplitude. The magnetic field generated by the DC excitation of the windings is distributed in an SSNN pattern along the outer circumference of the stator, similarly forming high-order harmonics with high magnetomotive force amplitude. The excitation magnetomotive force can be adjusted by changing the magnitude of the DC current in the windings. This fully utilizes the high-order harmonics in the magnetomotive force and combines them with the number of pole pairs P of the AC current in the windings. a Perform pole-slot matching design. Permanent magnet poles (5) number of pairs N pm DC current of winding, number of excitation pole pairs N fw , Number of rotor salient poles (6) N r Number of pole pairs P of AC current in winding a The following relationship must be satisfied:

[0010] ;

[0011] In the formula, m and n are both positive integers and both are greater than 1, and the number of excitation pole pairs N of the permanent magnet (5) pm With the number of excitation pole pairs N of the winding DC current fw When they are equal, it is represented as N. ec mN pm This indicates that only the permanent magnet (5) is energized at the mNth digit. pm First-order magnetomotive force, nN fw This indicates the nth winding when only the DC current of the winding is used for excitation. fw N r, m P a, m G pm, m The rotor salient pole number, winding AC armature pole pair number, and gear ratio are designed based on the m-order magnetomotive force under permanent magnet excitation only. r, n P a, n G fw, n These represent the number of salient poles of the rotor, the number of AC armature pole pairs of the winding, and the gear ratio, respectively, for a topology designed using the nth-order magnetomotive force when only the winding is DC excited.

[0012] Furthermore, the integrated winding (7) is constructed using two sets of three-phase windings, and is a double-layer winding. In the three-phase currents A1-B1-C1 of the first set of windings, the sinusoidal currents are phase-differentiated by 2π / 3, and the DC current is positive; in the three-phase currents A2-B2-C2 of the second set of windings, the sinusoidal currents are phase-differentiated by 2π / 3, and the DC current is negative. The neutral points of the two sets of windings are connected to provide a path for zero-sequence current. When connecting the windings, the influence of the coil pitch coefficient and distribution coefficient on the winding factor must be considered simultaneously.

[0013] Furthermore, both sinusoidal current and direct current are simultaneously introduced into the phase current of the integrated winding (7), thus the integrated winding (7) functions as both an AC current winding and a DC current excitation winding. The number of magnetic field pole pairs P generated by the AC current in the winding is... a Designed as 1 or 2, the number of magnetic field pole pairs N generated by the DC current in the winding is... fw The number of pole pairs N of the main magnetic field generated by the permanent magnet pm The direction of the DC current flowing through the winding is determined according to the right-hand rule. The direction of the magnetic field generated after the DC current flows through the winding is opposite to the magnetization direction of the permanent magnet (5) on the stator teeth (3) wound within it. Furthermore, the direction of the excitation magnetic field can be adjusted by changing the sign of the DC current, thereby enhancing or weakening the air gap magnetic field.

[0014] Furthermore, a system is established with the width θ of the permanent magnet (5) pm Stator slot opening width θ sw Iron pole (4) width θ st The expression for the harmonics of permanent magnet excitation and DC current excitation magnetomotive force, i.e., F pm, m (θ pm , θ st , θ sw ) and F fw, n (θ pm , θ st , θ sw Based on this, the expression for the higher harmonic enhancement factor λ is established. pm, m and λ fw, n , representing the ratio of the working air gap magnetic flux density generated by the higher harmonic magnetomotive force of the permanent magnet and DC current excitation to that of its fundamental magnetomotive force, respectively, are used to measure the magnitude of the higher harmonic enhancement. Further, an expression η is established for the utilization rate of the higher harmonics of the permanent magnet excitation and DC current excitation magnetomotive forces. pm, m and η fw, n This reflects the magnitude of torque enhancement capability of high-order harmonic design.

[0015] Furthermore, under different gear ratios, the width θ of the permanent magnet (5) pm Stator slot opening width θ sw Iron pole (4) width θ st Design variables to maximize η pm, m and η fw, n To optimize the objective, the maximum value of the objective is determined, thereby determining the values ​​of the three design variables and the gear ratio. Further, using maximum torque as the optimization objective and fixed copper loss as a prerequisite, the other design variables are optimized to obtain their values ​​at maximum torque.

[0016] This invention discloses a design method for a dual-three-phase hybrid excitation motor based on high-order harmonic utilization. The motor includes a rotor consisting only of an iron core with salient poles and a stator with permanent magnets and integrated windings. The design method includes the following steps:

[0017] The pole-slot matching relationship is determined so that the magnetic field generated by the permanent magnet is distributed in an NNSS-type array in space, and the magnetic field generated by the DC current flowing through the integrated winding is distributed in an SSNN-type array in space, so that both generate high-amplitude high-order harmonic magnetomotive force.

[0018] Step 1: Establish the correspondence between the three structural parameters of the motor—the width of the permanent magnet, the width of the iron pole, and the width of the stator slot opening—and the amplitude of the higher harmonic magnetomotive force;

[0019] Step 2: Based on the ratio of the higher harmonic magnetomotive force amplitude to the fundamental magnetomotive force amplitude, and the ratio of the gear ratio corresponding to the higher harmonic design to the gear ratio corresponding to the fundamental design, construct a higher harmonic utilization parameter to measure the torque enhancement capability of the higher harmonic design. The utilization parameter is defined for permanent magnet excitation and DC current excitation respectively.

[0020] Step 3: With maximizing the high-order harmonic utilization rate parameter of the permanent magnet excitation and the high-order harmonic utilization rate parameter of the DC current excitation as the common optimization objectives, perform multi-objective optimization on the permanent magnet width, iron pole width, stator slot opening width and gear ratio, and determine the above parameter values ​​that make the two utilization rate parameters reach their maximum simultaneously.

[0021] Step 4: Under the premise of fixed motor copper loss, with the optimization goal of maximizing motor output torque, optimize the other motor structural parameters except for the permanent magnet width, iron pole width, and stator slot opening width to obtain the optimal values ​​of the other structural parameters that maximize torque.

[0022] Furthermore, the correspondence in step one is established in the following way:

[0023] Mathematical modeling and Fourier analysis were performed on the magnetomotive force waveforms generated by excitation of permanent magnets alone and by excitation of DC current from windings alone, respectively, to obtain the magnetomotive force harmonic amplitude expression with the width of the permanent magnet, the width of the iron pole, and the width of the stator slot opening as variables.

[0024] Furthermore, the multi-objective optimization in step three employs a non-dominated sorting genetic algorithm II, and by generating a Pareto graph, the parameter solution set is obtained when the two higher harmonic utilization parameters are simultaneously maximized based on the Pareto front.

[0025] Furthermore, in step four, before optimizing the remaining structural parameters, a sensitivity analysis method is introduced to distinguish the remaining structural parameters into insensitive parameters and sensitive parameters.

[0026] The non-sensitive parameter is obtained by scanning a finite element model to obtain its optimal value that maximizes the torque;

[0027] The sensitivity parameter is further obtained by combining the finite element model with the optimization algorithm to obtain the optimal value that maximizes the torque.

[0028] The optimization process for the aforementioned sensitivity parameters specifically includes:

[0029] Using the aforementioned sensitivity parameters as optimization variables, a sample database is generated through a central composite design method;

[0030] Under the condition that the stator inner diameter, rotor outer diameter, effective shaft length, air gap length, permanent magnet width, iron pole width, and stator slot opening width determined in step three remain unchanged, and the copper loss is the same, the torque value corresponding to each sample in the sample database is obtained by using the finite element model.

[0031] A high-precision regression equation is established based on curve fitting to characterize the relationship between the sensitive parameter and the torque;

[0032] The regression equation is combined with the non-dominated sorting genetic algorithm II to construct an optimization model, and the optimal value of the sensitivity parameter that maximizes the torque is obtained by solving the problem.

[0033] Furthermore, the sensitive parameters include at least: the lower width of the rotor salient pole, the upper width of the rotor salient pole, the stator tooth width, the rotor yoke thickness, the stator slot height, and the permanent magnet thickness.

[0034] Furthermore, it also includes the winding design steps:

[0035] The integrated winding is designed as a double three-phase winding, with each phase winding consisting of multiple coils connected in series, and adopts a double-layer distributed winding.

[0036] In the first set of three-phase windings, each phase is supplied with a sinusoidal alternating current with a phase difference of 120 degrees and a positive direct current is superimposed; in the second set of three-phase windings, each phase is supplied with a sinusoidal alternating current with a phase difference of 120 degrees and a negative direct current is superimposed; the neutral points of the two sets of windings are connected to each other to provide a path for zero-sequence current.

[0037] After adopting the above design scheme, the present invention can achieve the following beneficial effects:

[0038] 1. This invention derives a high-order harmonic design method for pole-slot coupling through theoretical analysis. It establishes an expression η for the utilization rate of high-order harmonics in the magnetomotive force of permanent magnet excitation and DC current excitation. pm, mand η fw, n This reflects the magnitude of torque enhancement capability achieved through higher harmonic design. The goal is to maximize η. pm, m and η fw, n To optimize the objective, the maximum value of the objective is determined, thereby determining the values ​​of the three design variables and the gear ratio. Further, with maximum torque as the optimization objective and fixed copper loss as a prerequisite, the other design variables are optimized to obtain their values ​​at maximum torque. This allows for the design of a high-torque motor. This design method fully considers the higher-order components of the magnetomotive force, compensating for the shortcomings of motor topology design based on higher-order harmonic components of the magnetomotive force.

[0039] 2. This invention employs an NNSS-type permanent magnet array and an SSNN-type magnetomotive force generated by the distribution of DC current in the windings, thereby enhancing the amplitude of higher harmonic magnetomotive force. The topology is not designed based on the conventional fundamental magnetomotive force, but rather on the higher harmonics of the magnetomotive force. Therefore, the main operating wave of the motor's magnetomotive force is a higher harmonic, rather than the traditional fundamental magnetomotive force. The topology includes a rotor and a stator assembly, wherein the number of stator slots is N. s Both the permanent magnet excitation source and the winding DC current excitation source are located in the stator. The air gap magnetic field can be enhanced or weakened by adjusting the magnitude and direction of the winding DC current. The rotor consists only of an iron core containing nitrogen. r With one salient pole and no excitation source, the structure is simple and improves the reliability of motor operation. Attached Figure Description

[0040] Figure 1 The following are Fourier analysis diagrams of the permanent magnet excitation magnetomotive force and the winding DC current excitation magnetomotive force in embodiments of the present invention.

[0041] Figure 2 This is a schematic diagram of a hybrid excitation motor structure designed for high-order harmonics in an embodiment of the present invention, with the specific number of rotor salient poles (6) N. r / Number of pole pairs for AC current in winding P a The structure of the motor is distinguished by the following method: (a) is 13 / 2, (b) is 17 / 2, (c) is 19 / 2, (d) is 23 / 2, (e) is 14 / 1, (f) is 16 / 1, (g) is 20 / 1, and (h) is 22 / 1; (c) represents the motor with the maximum torque in the embodiment of the present invention.

[0042] Figure 3 Average torque diagram of the topology designed for 8 higher harmonics;

[0043] Figure 4 This is a schematic diagram of the integrated winding wiring of the maximum torque motor in an embodiment of the present invention;

[0044] Figure 5The magnetic field diagrams of this embodiment of the invention are shown below, wherein (a) is a magnetic field diagram of permanent magnet only, (b) is a magnetic field diagram of positive DC current, and (c) is a magnetic field diagram of negative DC current.

[0045] Figure 6 The following are Fourier analysis diagrams of the air gap magnetic flux density under permanent magnet excitation and under winding DC current excitation of the maximum torque motor according to the embodiments of the present invention: (a) is the air gap magnetic flux density waveform under permanent magnet excitation only; (b) is the air gap magnetic flux density waveform under DC excitation only; (c) is the harmonic order analysis diagram of the air gap magnetic flux density under permanent magnet excitation and DC excitation only.

[0046] Figure 7 The flux linkage waveforms of the maximum torque motor in this embodiment of the invention are shown in the mixed field weakening, permanent magnet excitation only, and mixed magnetization.

[0047] Figure 8 This is a graph showing the contribution ratio of harmonic magnetomotive force to fundamental no-load back EMF of the maximum torque motor and the conventional motor in the embodiments of the present invention.

[0048] Figure 9 The torque waveforms of the maximum torque motor in this embodiment of the invention are shown in the forms of mixed field weakening, permanent magnet excitation only, and mixed field enhancement.

[0049] Figure 10 This is a comparison chart of the average torque of the maximum torque motor and the conventional motor under different current densities in this embodiment of the invention;

[0050] In the diagram: 1. Motor rotor, 2. Motor stator, 3. Stator teeth, 4. Iron pole, 5. Permanent magnet, 6. Rotor salient pole, 7. Integrated winding. Detailed Implementation

[0051] To make the objectives, technical solutions, and effects of this invention clearer, the following description is provided in conjunction with the appendix. Figures 1-10 The structural features and beneficial effects of the motor of the present invention are described in detail with specific embodiments.

[0052] like Figure 1 As shown, a dual-three-phase hybrid excitation motor structure and its design method are disclosed. The motor structure includes a rotor (1) and a stator (2). The rotor (1) has N r Each salient pole (6) consists only of an iron core and has no excitation source; the stator (2) includes a stator iron core, stator teeth (3), iron poles (4), permanent magnets (5), and integrated windings (7), wherein the stator iron core is an open slot design and the number of slots in the stator (2) is N. s A winding in which both alternating current and direct current are simultaneously circulated in the phase current is called an integrated winding (7), which uses a double-layer winding, 2N s N is composed of conductors. s Each phase winding consists of N coils. sThe stator consists of six coils connected in series, forming two sets of three-phase windings, i.e., double three-phase windings. The integrated winding (7) is distributed in the open slots of the stator core and wound on the stator teeth (3) using a distributed connection method. N is distributed along the circumference of the stator (2). s One permanent magnet (5) is placed on each stator tooth (3). The permanent magnet is located between two iron poles (4). The magnetization direction of the permanent magnet (5) is radial. The smallest unit of permanent magnet distribution consists of two N-pole permanent magnets and two S-pole permanent magnets, which is denoted as NNSS type permanent magnet array. The included angle between the centers of adjacent permanent magnets is 2π / N. s The stator and rotor cores are made of magnetically conductive materials such as silicon steel sheets, while the permanent magnets (5) are made of neodymium iron boron. The permanent magnets (5) are embedded in the top of the stator teeth (3), and the included angle between the centers of adjacent permanent magnets is 2π / N. s The magnetization direction of the N-pole permanent magnet (5) is defined as radial magnetization, away from the center, while the magnetization direction of the S-pole permanent magnet (5) is radial magnetization, pointing towards the center. s Five permanent magnets (5) are distributed along the circumference to form N s The main magnetic field of the / 4 pole pair.

[0053] In this method, the permanent magnet array is distributed in an NNSS pattern along the outer circumference of the stator, forming high-order harmonics with high magnetomotive force amplitude. The magnetic field generated by the DC excitation of the windings is distributed in an SSNN pattern along the outer circumference of the stator, similarly forming high-order harmonics with high magnetomotive force amplitude. The excitation magnetomotive force can be adjusted by changing the magnitude of the DC current in the windings. This fully utilizes the high-order harmonics in the magnetomotive force and combines them with the number of pole pairs P of the AC current in the windings. a Perform pole-slot matching design. Permanent magnet poles (5) number of pairs N pm DC current of winding, number of excitation pole pairs N fw , Number of rotor salient poles (6) N r Number of pole pairs P of AC current in winding a The following relationship must be satisfied:

[0054] ;

[0055] In the formula, m and n are both positive integers and both are greater than 1, and the number of excitation pole pairs N of the permanent magnet (5) pm With the number of excitation pole pairs N of the winding DC current fw When they are equal, it is represented as N. ec mN pm This indicates that only the permanent magnet (5) is energized at the mNth digit. pm First-order magnetomotive force, nN fw This indicates the nth winding when only the DC current of the winding is used for excitation. fw N r, m P a, m G pm, mThese represent the number of salient poles of the rotor, the number of AC armature pole pairs of the winding, and the gear ratio, respectively, for a topology designed using the m-order magnetomotive force under permanent magnet excitation only. r, n P a, n G fw, n These represent the number of salient poles of the rotor, the number of AC armature pole pairs of the winding, and the gear ratio, respectively, for a topology designed using the nth-order magnetomotive force when only the winding is DC excited.

[0056] The integrated winding (7) is constructed using two sets of three-phase windings, and is a double-layer winding. In the three-phase currents A1-B1-C1 of the first set of windings, the sinusoidal currents are phase-differentiated by 2π / 3, and the DC current is positive; in the three-phase currents A2-B2-C2 of the second set of windings, the sinusoidal currents are phase-differentiated by 2π / 3, and the DC current is negative. The neutral points of the two sets of windings are connected to provide a path for zero-sequence current. When connecting the windings, the influence of the coil pitch coefficient and distribution coefficient on the winding factor must be considered simultaneously.

[0057] The integrated winding (7) simultaneously carries both sinusoidal and direct current in its phase current, thus functioning as both an AC current winding and a DC current excitation winding. The number of magnetic field pole pairs P generated by the AC current in the winding is... a Designed as 1 or 2, the number of magnetic field pole pairs N generated by the DC current in the winding is... fw The number of pole pairs N of the main magnetic field generated by the permanent magnet pm The direction of the DC current flowing through the winding is determined according to the right-hand rule. The direction of the magnetic field generated after the DC current flows through the winding is opposite to the magnetization direction of the permanent magnet (5) on the stator teeth (3) wound within it. Furthermore, the direction of the excitation magnetic field can be adjusted by changing the sign of the DC current, thereby enhancing or weakening the air gap magnetic field.

[0058] Establish a permanent magnet (5) with a width θ pm Stator slot opening width θ sw Iron pole (4) width θ st The expression for the harmonics of permanent magnet excitation and DC current excitation magnetomotive force, i.e., F pm, m (θ pm , θ st , θ sw ) and F fw, n (θ pm , θ st , θ sw Based on this, the expression for the higher harmonic enhancement factor λ is established. pm, m and λ fw, n , representing the ratio of the working air gap magnetic flux density generated by the higher harmonic magnetomotive force of the permanent magnet and DC current excitation to that of its fundamental magnetomotive force, respectively, are used to measure the magnitude of the higher harmonic enhancement. Further, an expression η is established for the utilization rate of the higher harmonics of the permanent magnet excitation and DC current excitation magnetomotive forces. pm, m and ηfw, n This reflects the magnitude of torque enhancement capability of high-order harmonic design.

[0059] At different gear ratios, with the permanent magnet (5) width θ pm Stator slot opening width θ sw Iron pole (4) width θ st Design variables to maximize η pm, m and η fw, n To optimize the objective, the maximum value of the objective is determined, thereby determining the values ​​of the three design variables and the gear ratio. Further, using maximum torque as the optimization objective and fixed copper loss as a prerequisite, the other design variables are optimized to obtain their values ​​at maximum torque.

[0060] The stator core and rotor core are made of magnetically conductive materials such as silicon steel sheets, and the permanent magnet (5) is made of neodymium iron boron material.

[0061] Furthermore, it is necessary to analyze the relationship between the amplitude E of the unloaded back EMF fundamental wave and the velocity ω of the rotating magnetic field in the higher harmonics. m The relationship between them is as follows:

[0062] ;

[0063] In the formula, n c r is the number of coil turns. g l is the air gap radius. ef This represents the effective shaft length of the motor. kw1 is the winding coefficient, and ω... m ω is the velocity of the rotating magnetic field, B is the amplitude of the air gap magnetic flux density of the main operating harmonic, and ω is the velocity of the rotating magnetic field. r G represents the rotor's mechanical speed. r This is the gear ratio.

[0064] As can be seen from the relationship, without considering other constants, the rotating magnetic field velocity and the air gap magnetic flux density amplitude are the two main factors affecting the fundamental no-load back EMF. Although the air gap magnetic flux density amplitude decreases for higher harmonics, the rotating magnetic field velocity increases even more. Overall, higher harmonic design helps to improve the no-load back EMF.

[0065] Furthermore, based on the number of pole pairs P of the winding AC current... a Number of phases m, number of stator slots N s It can calculate the slot pitch angle α, the number of slots per pole per phase q, and the pole pitch τ, at which point the distribution coefficient k can be obtained. d1 If it is a constant, then the pitch coefficient k can be increased by adjusting the coil pitch y1. p1 To further improve the winding factor k w1 When the coil pitch y1 < τ, the coil is connected in a short-pitch configuration; when the coil pitch y1 = τ, the coil is connected in a full-pitch configuration.

[0066] ;

[0067] Furthermore, the integrated winding (7) is simultaneously supplied with both AC and DC current. The first set of three-phase windings is denoted as A1-B1-C1, and the second set of three-phase windings is denoted as A2-B2-C2, as shown in the following formula.

[0068] ;

[0069] In the formula, I ac and I dc These are the effective values ​​of the alternating current and the direct current, respectively. ω e It is electric angular velocity.

[0070] Furthermore, Explanation 1 states that mathematical modeling of the magnetomotive force waves generated by permanent magnet excitation only and DC current excitation only of the windings is performed, followed by Fourier analysis, yielding the following mathematical expressions for the magnetomotive force:

[0071] ;

[0072] in:

[0073] In the formula, F pm (θ) and F fw (θ) represent the magnetomotive force generated by excitation of only the permanent magnet and by excitation of only the DC current of the windings, respectively. F pm, m (θ pm , θ st , θ sw ) and F fw, n (θ pm , θ st , θ sw The mN values ​​generated by excitation of only permanent magnets and excitation of only winding DC current are respectively the mN values ​​generated by excitation of only permanent magnets and excitation of only winding DC current. pm The magnitude and the nth value fw Amplitude values. θ is the mechanical angle along the circumference of the stator air gap. F1 and F2 are the magnetomotive force amplitudes generated by permanent magnet excitation and winding DC current excitation, respectively.

[0074] Analysis revealed that the 5th harmonic (5N) with a relatively high magnetomotive force amplitude pm =5N fw ) or 7th harmonic (7N) pm =7N fw (), can be selected as the main operating harmonic. Based on the number of permanent magnet pole pairs N pm DC current of winding, number of excitation pole pairs N fw Number of rotor salient poles N r Number of pole pairs P of AC current in winding a The relationship that is satisfied determines the corresponding number N of rotor salient poles. rThe design incorporates extreme grooves.

[0075] Explanation 2: The rotor has N r Each salient pole (6) consists only of an iron core and has no excitation source. Its magnetic permeability expression is:

[0076] ;

[0077] Among them, P r, j Let θ be the amplitude of the j-th harmonic permeability component, and θ0 be the initial angle of the rotor position.

[0078] Explanation 3: By multiplying the magnetomotive force by the magnetic permeability, the expressions for the air gap magnetic flux density when only the permanent magnet is excited and when only the winding DC current is excited are obtained respectively:

[0079] ;

[0080] In the formula, v=mN pm ±jN r u=nN fw ±jN r B v B represents the amplitude of the v-th air gap magnetic flux density harmonic under permanent magnet excitation only. u This represents the amplitude of the u-th air gap magnetic flux density harmonic when only the winding DC current is excited.

[0081] Note 4: Calculate the expression for the utilization rate of higher harmonics of the magnetomotive force for permanent magnet excitation and DC current excitation, η. pm, m and η fw, n As shown in the following formula:

[0082] ;

[0083] In the formula, B pm (1,−1) and B pm (m,−1) represent the air gap magnetic flux density amplitudes generated by the fundamental magnetomotive force and the m-th harmonic magnetomotive force, respectively, when only the permanent magnet is excited. The ratio of the two is denoted as the higher harmonic enhancement factor λ. pm, m G pm, m and G pm, 1 These are the gear ratios designed from the m-th harmonic magnetomotive force and the fundamental magnetomotive force when only the permanent magnet is excited, respectively, and the ratio of the two is denoted as ξ. pm, m B fw (1,−1) and B fw (n,−1) represent the air gap magnetic flux density amplitudes generated by the fundamental magnetomotive force and the nth harmonic magnetomotive force, respectively, when only the winding is excited by DC current. The ratio of the two is denoted as the higher harmonic enhancement factor λ. fw, n G fw, n and G fw, 1These are the gear ratios designed from the nth harmonic magnetomotive force and the fundamental magnetomotive force when only the winding is excited by DC current. The ratio of the two is denoted as ξ. fw, n Gear ratio G pm, m G fw, n With the number of rotor salient poles N r Number of armature pole pairs P in the winding a Relatedly, its value is required to be greater than 6 during the design phase.

[0084] Furthermore, firstly, through the expression η pm, m and η fw, n The optimization objective is to maximize both values, and a multi-objective optimization is performed using a non-dominated sorting genetic algorithm II. Furthermore, a Pareto graph can be generated, and η can be obtained based on the Pareto front. pm, m and η fw, n The solution set of design variables when the maximum is reached. Its mathematical expression can be represented as:

[0085] ;

[0086] Determine the optimization of three design variables θ pm , θ st , θ sw The value of is determined, and the gear ratio G of the motor topology is determined. pm, m With G fw, n .

[0087] Secondly, the design variable θ has been determined above. pm , θ st , θ sw The remaining structural parameters still need optimization. To improve optimization efficiency, a sensitivity analysis method is introduced, thereby dividing the motor's structural parameters into insensitive and sensitive parameters. The optimal values ​​for insensitive parameters are obtained by scanning the finite element model to obtain their maximum torque, while the optimal values ​​for sensitive parameters are obtained by combining the finite element model with optimization algorithms to obtain their maximum torque. Their mathematical expressions can be represented as follows:

[0088] ;

[0089] In the formula, x i Let y be the i-th design variable and y be the optimization objective, then E(y / x) i ) is the xth i The average value of y when it remains constant, V(E(y / x) i E(y / x) i The variance of y is V(y), and the variance of y is S(x). i ) is x i Sensitivity to y.

[0090] Finally, using the sensitivity parameter as the optimization variable, a sample database is formed through a central composite design. This ensures the inner diameter R of the stator (2) is... in Rotor (1) outer diameter R ro Effective axis length l ef Air gap length δ a , Permanent magnet (5) Width θ pm Iron pole (4) width θ st Stator (2) slot opening width θ sw The optimization objective remains unchanged, assuming maximum torque and constant copper loss. The target value from the sample library is obtained through a finite element model, and a curve fitting method is used to model the regression equation with high accuracy. The regression equation is then combined with the non-dominated sorting genetic algorithm II to construct the following optimization model:

[0091] ;

[0092] The rotor salient pole (6) with the maximum torque can be obtained at its lower width θ. rt1 upper width θ of rotor salient pole (6) rt2 Stator (2) Tooth width θ s 、 Rotor (1) yoke thickness h ry Stator (2) slot height h s1 Permanent magnet (5) thickness h pm Optimal values ​​for parameter variables.

[0093] The optimized motor with 12 stator slots and 19 rotor pole pairs has the maximum torque. Its structural parameters are shown in Table 1 below.

[0094] Table 1 shows the structural parameters of a motor with 12 stator slots and 19 pole pairs on the rotor:

[0095] ;

[0096] Figure 1 The waveforms of the permanent magnet excitation magnetomotive force (GMMF) and the winding DC current excitation magnetomotive force (GMMF) of the motor in this embodiment of the invention, along with their Fourier analysis diagrams, are shown. The generated slotless GMMF can be considered as a square wave. The magnetization direction of the permanent magnet (5) is radial magnetization. The smallest unit of the permanent magnet distribution consists of two N-pole permanent magnets and two S-pole permanent magnets, with a 30° angle between the centers of adjacent permanent magnets. The main pole pair formed is N... s A permanent magnet magnetic field of / 4. When a direct current is applied to the integrated winding (7), a main pole pair of N is also generated. sA DC magnetic field of / 4. When fully considering the higher harmonics of the magnetomotive force, it is necessary to consider both the magnitude of the permanent magnet magnetomotive force and the magnitude of the DC current excitation magnetomotive force. Fourier analysis shows that the magnetomotive force generated by this permanent magnet array and DC current excitation distribution method, in addition to having a high-amplitude fundamental magnetomotive force (N... ec In addition to this, it also has a high amplitude 5th harmonic (5N). ec ) and the 7th harmonic (7N) ec This allows for a smaller reduction in the amplitude of the air gap magnetic flux density, which lays a good foundation for high-order harmonic design of the structure.

[0097] Figure 2 This is a schematic diagram of a hybrid excitation motor structure designed for high-order harmonics in an embodiment of the present invention. It maintains the same external rotor structure, rotor outer diameter of 140mm, stator inner diameter of 25mm, and air gap length of 0.6mm. The specific number of rotor salient poles (6) N is used as an example. r / Number of pole pairs for AC current in winding P a The structure of the motor is distinguished by the following method: (a) 13 / 2, rotor salient poles (6) number N r The number of pole pairs P of the winding AC current is 13. a (a) 2, coil pitch is 3; (b) 17 / 2, coil pitch is 3; (c) 19 / 2, coil pitch is 3; (d) 23 / 2, coil pitch is 3; (e) 14 / 1, coil pitch is 2; (f) 16 / 1, coil pitch is 2; (g) 20 / 1, coil pitch is 2; (h) 22 / 1, coil pitch is 6. For example... Figure 2 As shown, the motor includes a rotor (1) and a stator (2). The rotor (1) has N r Each salient pole (6) consists only of an iron core and has no excitation source; the stator (2) includes a stator iron core, stator teeth (3), iron poles (4), permanent magnets (5), and integrated windings (7), wherein the stator iron core is an open slot design and the number of slots in the stator (2) is N. s A winding in which both alternating current and direct current are simultaneously circulated in the phase current is called an integrated winding (7), which uses a double-layer winding, 2N s N is composed of conductors. s Each phase winding consists of N coils. s The stator consists of six coils connected in series, forming two sets of three-phase windings, i.e., double three-phase windings. The integrated winding (7) is distributed in the open slots of the stator core and wound on the stator teeth (3) using a distributed connection method. N is distributed along the circumference of the stator (2). sOne permanent magnet (5) is placed on each stator tooth (3). The permanent magnet is located between two iron poles (4). The magnetization direction of the permanent magnet (5) is radial. The smallest unit of permanent magnet distribution consists of two N-pole permanent magnets and two S-pole permanent magnets, which is denoted as NNSS type permanent magnet array. The included angle between the centers of adjacent permanent magnets is 2π / N. s The stator core and rotor core are made of magnetically conductive materials such as silicon steel sheets, and the permanent magnet (5) is made of neodymium iron boron material.

[0098] like Figure 3 The figure shows the average torque diagram of the topology designed for 8 higher harmonics. Regardless of the number of pole pairs P of the winding AC current... a Whether it is 2 or 1, the average torque varies with the gear ratio G. pm,m = G fw,n G r The increase in torque exhibits a trend of first increasing and then decreasing, indicating the existence of a motor topology with the highest torque. Furthermore, it is influenced by the 5th harmonic of the magnetomotive force (5N). pm =5N fw ) or 7th harmonic (7N) pm =7N fw The average torque of the designed motors is greater than that of traditional motors.

[0099] like Figure 4 As shown, this is the winding connection of the motor with the maximum torque in the embodiment. Each phase winding consists of N... s It consists of 6 coils connected in series, with a coil pitch of N. s / 4. The integrated winding (7) is made of two sets of three-phase windings and is a double-layer winding. In the three-phase currents A1-B1-C1 of the first set of windings, the sinusoidal currents are phased by 2π / 3, and the DC current is positive; in the three-phase currents A2-B2-C2 of the second set of windings, the sinusoidal currents are phased by 2π / 3, and the DC current is negative. The neutral points of the two sets of windings are connected to provide a path for zero-sequence current.

[0100] Figure 5 The magnetic field lines for permanent magnet excitation, positive DC current flow, and negative DC current flow of the maximum torque motor in this embodiment of the invention are shown. Figure 5 As shown in (a), the permanent magnet magnetic field line path is: from permanent magnet (5) → air gap → rotor salient pole (6) → rotor yoke → rotor salient pole (6) → air gap → permanent magnet (5) → stator teeth (3) → stator yoke → stator teeth (3) → permanent magnet (5), forming a closed magnetic field line path. This magnetic path does not pass through the iron pole (4). Figure 5As shown in (b), the magnetic field path for a positive DC current is: iron pole (4) → air gap → rotor salient pole (6) → rotor yoke → rotor salient pole (6) → air gap → iron pole (4) → stator teeth (3) → stator yoke → stator teeth (3) → iron pole (4), forming a closed magnetic field path. This magnetic path does not pass through the permanent magnet (5), reducing the irreversible demagnetization of the permanent magnet (5). Figure 5 As shown in (c), the magnetic field line path is the same as that of the magnetic field line path of the positive DC current, only in the opposite direction.

[0101] Figure 6 The figures show the air gap magnetic flux density waveforms and Fourier analysis diagrams for the maximum torque motor of this invention under permanent magnet excitation only and DC current excitation only for windings. (a) is the air gap magnetic flux density waveform under permanent magnet excitation only, and (b) is the air gap magnetic flux density waveform under DC excitation only. (c) is the Fourier harmonic analysis diagram for both. It can be seen that B pm (1,−1) and B pm (7,−1) are 0.090T and 0.035T respectively, B pm (1,−1) / B pm The ratio of (7,−1) is 2.57, which is higher than that of the fundamental magnetomotive force design and the 7th harmonic design (7N). pm =7N fw The magnetomotive force amplitude decreased by 157%. fw (1,−1) and B fw (7,−1) are 0.080T and 0.053T respectively, B fw (1,−1) / B fw The ratio of (7,−1) is 1.5, compared to the fundamental magnetomotive force design, the 7th harmonic (7N) pm =7N fw The design magnetomotive force amplitude was reduced by 50%. The 7th harmonic (7N) of both... pm =7N fw Although the air gap magnetic flux density amplitude of the design is reduced, the 7th harmonic (7N) pm =7N fw The designed electromagnetic rotation speed is 8 times that of the electromagnetic rotation speed designed for the fundamental magnetomotive force. Overall, this can increase the no-load back EMF.

[0102] Figure 7 The maximum torque motor in this embodiment of the invention operates under mixed field weakening conditions (current density of −3.8 A / mm²). 2 Permanent magnet excitation only (current density of 0 A / mm²) 2 Hybrid magnetization (current density of +3.8A / mm²) 2The flux linkages of the three components are 0.0032 Wb, 0.0195 Wb, and 0.0358 Wb, respectively. The flux regulation ratio is defined as the ratio of the fundamental amplitude of the mixed magnetizing flux linkage minus the fundamental amplitude of the mixed magnetizing flux linkage to the fundamental amplitude of the permanent magnet excitation flux linkage alone, expressed as a percentage. The calculated flux regulation ratio under this applied current density is 167%, while the calculated flux regulation ratio of a conventional motor under the same conditions is 43%, indicating that the maximum torque motor has good flux regulation capability.

[0103] Figure 8 This diagram shows the contribution ratio of harmonic magnetomotive force to the fundamental no-load back EMF of the maximum torque motor and a conventional motor according to embodiments of the present invention. When comparing with a conventional motor, one can... Figure 8 As can be seen from this, in traditional motors, when only permanent magnets are excited, the fundamental frequency (N) ec ), 3 times (3N) ec The harmonic magnetomotive force makes a positive contribution to the no-load back electromotive force, the 5th (5N) ec ), 7 times (7N) ec Harmonic magnetomotive force has a negative contribution to the no-load back EMF; when only the winding DC current is used for excitation, the fundamental frequency (N) ec ), 5 times (5N) ec ), 7 times (7N) ec The harmonic magnetomotive force makes a positive contribution to the no-load back electromotive force, the 3rd (3N) ec Harmonic magnetomotive force (EMF) makes a negative contribution to the no-load back EMF. In the maximum torque motor of the embodiment, when only permanent magnet excitation is used, the third (3N) harmonic magnetomotive force (EMF) makes a negative contribution to the no-load back EMF. ec ), 5 times (5N) ec ), 7 times (7N) ec ), 11 times (11N) ec ), 15 times (15N) ec The harmonic magnetomotive force (MMF) contributes positively to the no-load back EMF, while the fundamental magnetomotive force (MMF) contributes negatively to the no-load back EMF. When only the winding is excited by DC current, the fundamental (N) ec ), 5 times (5N) ec ), 7 times (7N) ec ), 11 times (11N) ec The harmonic magnetomotive force makes a positive contribution to the no-load back electromotive force, the 3rd (3N) ec ), 15 times (15N) ec Harmonics contribute negatively to the no-load back EMF. In summary, since traditional motors are designed based on the fundamental frequency of the magnetomotive force, the fundamental frequency (N...)... ec The magnetomotive force contributes the most to the fundamental no-load back EMF. The motor in the invention embodiment is based on the 7th (7N) power of the magnetomotive force. ec The design incorporates harmonics, therefore the 7th (7N) harmonic... ec The harmonic magnetomotive force contributes the most to the fundamental no-load back EMF.

[0104] Figure 9 This is the loaded torque waveform of the maximum torque motor in this embodiment of the invention. Under the same copper loss, the torque waveforms of the integrated winding (7) under mixed magnetization, permanent magnet excitation only, and mixed demagnetization are shown. The motor speed is 500 r / min, and the AC current is 5 A / mm². 2 The DC current for the three cases is −3.8 A / mm. 2 0A / mm 2 +3.8A / mm 2 As can be seen from the figure, the average output torque is 5.40 Nm, 8.45 Nm, and 11.68 Nm, and the output torque increases almost linearly in the three cases.

[0105] Figure 10 The figures show the torque waveforms of the maximum torque motor and a conventional motor under different current densities according to embodiments of the present invention. The speed is 500 r / min, and the phase current density is from 1 A / mm². 2 Up to 8A / mm 2 Step size is 1A / mm 2 It can be seen that as the current density increases, the average torque of both the conventional motor and the motor in the example also increases, and the increase in average torque of the motor in the example is greater than that of the conventional motor. The transient torque of the two motors within one electrical cycle at a current density of 7.8 A / mm² is also given. The average torque of the conventional motor is 6.38 Nm, with a torque ripple of 9.20%; the average torque of the motor in the example is 11.68 Nm, with a torque ripple of 11.72%. Compared with the conventional motor, the average torque of the motor in the example is increased by 83.1%, while the torque ripple only increases slightly.

[0106] In summary, the SSNN type, generated by employing an NNSS-type permanent magnet array and the distribution of DC current in the windings, enhances the amplitude of higher harmonic magnetomotive force (MTF). The topology is not designed based on the conventional fundamental MMF, but rather on the higher harmonics of the MMF. Therefore, the main operating harmonic MMF of this motor is a higher harmonic, rather than the traditional fundamental MMF. The topology includes a rotor and stator assembly, with N stator slots. s Both the permanent magnet excitation source and the winding DC current excitation source are located in the stator. The air gap magnetic field can be enhanced or weakened by adjusting the magnitude and direction of the winding DC current. The rotor consists only of an iron core, has no excitation source, and contains nitrogen. r The single salient pole design simplifies the structure and improves the reliability of motor operation. A high-order harmonic design method for pole-slot matching is derived through theoretical analysis. An expression η for the utilization rate of high-order harmonics of permanent magnet excitation and DC current excitation magnetomotive force is established. pm, m and η fw, n This reflects the magnitude of torque enhancement capability achieved through higher harmonic design. The goal is to maximize η. pm, m and ηfw, n To optimize the objective, the maximum value of the objective is determined, thereby determining the values ​​of the three design variables and the gear ratio. Further, with maximum torque as the optimization objective and fixed copper loss as a prerequisite, the other design variables are optimized to obtain their values ​​at maximum torque. This allows for the design of a high-torque motor. This design method fully considers the higher-order components of the magnetomotive force, compensating for the shortcomings of motor topology design based on higher-order harmonic components of the magnetomotive force.

[0107] Although embodiments of the invention have been illustrated and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A dual-three-phase hybrid excitation motor structure, characterized in that: It includes a rotor (1) and a stator (2); the rotor (1) has N r Each salient pole (6) consists only of an iron core and has no excitation source; the stator (2) includes a stator iron core, stator teeth (3), iron poles (4), permanent magnets (5), and integrated windings (7), wherein the stator iron core is an open slot design and the number of slots in the stator (2) is N. s A winding in which both alternating current and direct current are simultaneously circulated in the phase current is called an integrated winding (7), which uses a double-layer winding, 2N s N is composed of conductors. s Each phase winding consists of N coils. s The stator consists of six coils connected in series, forming two sets of three-phase windings, i.e., double three-phase windings. The integrated winding (7) is distributed in the open slots of the stator core and wound on the stator teeth (3) using a distributed connection method. N is distributed along the circumference on the stator (2). s One permanent magnet (5) is placed on each stator tooth (3). The permanent magnet is located between two iron poles (4). The magnetization direction of the permanent magnet (5) is radial. The smallest unit of the permanent magnet distribution consists of two N-pole permanent magnets and two S-pole permanent magnets, which is denoted as NNSS type permanent magnet array. The center-to-center angle between adjacent permanent magnets is 2π / N. s The permanent magnet (5) is embedded in the top of the stator tooth (3), and the included angle between the centers of adjacent permanent magnets is 2π / N. s The magnetization direction of the N-pole permanent magnet (5) is defined as radial magnetization, away from the center, and the magnetization direction of the S-pole permanent magnet (5) is radial magnetization, pointing towards the center. s Five permanent magnets (5) are distributed along the circumference to form N s The main magnetic field of the / 4 pole pair.

2. The dual three-phase hybrid excitation motor structure as described in claim 1, characterized in that: The permanent magnet array is distributed in an NNSS pattern along the outer circumference of the stator, forming high-order harmonics with high magnetomotive force amplitude. The magnetic field generated by the DC excitation of the windings is distributed in an SSNN pattern along the outer circumference of the stator, also forming high-order harmonics with high magnetomotive force amplitude. The excitation magnetomotive force is adjusted by changing the magnitude of the DC current in the windings. This fully utilizes the high-order harmonics in the magnetomotive force and combines them with the number of pole pairs P of the AC current in the windings. a Perform pole-slot matching design; permanent magnet (5) number of pole pairs N pm DC current of winding, number of excitation pole pairs N fw , Number of rotor salient poles (6) N r Number of pole pairs P of AC current in winding a The following relationship must be satisfied: ； In the formula, m and n are both positive integers and both are greater than 1, and the number of excitation pole pairs N of the permanent magnet (5) pm The number of excitation pole pairs N of the winding DC current fw When they are equal, N pm With N fw Represented as N ec mN pm This indicates that only the permanent magnet (5) is energized at the mNth digit. pm First-order magnetomotive force, nN fw This indicates the nth winding when only the DC current of the winding is used for excitation. fw N r, m P a, m G pm, m The rotor salient pole number, winding AC armature pole pair number, and gear ratio are designed based on the m-order magnetomotive force under permanent magnet excitation only. r, n P a, n G fw, n These represent the number of salient poles of the rotor, the number of AC armature pole pairs of the winding, and the gear ratio, respectively, for a topology designed using the nth-order magnetomotive force when only the winding is DC excited.

3. The dual three-phase hybrid excitation motor structure as described in claim 1, characterized in that: The integrated winding (7) is made of two sets of three-phase windings and is a double-layer winding; in the three-phase current A1-B1-C1 of the first set of windings, the sinusoidal current phase difference is 2π / 3, and the DC current is positive; in the three-phase current A2-B2-C2 of the second set of windings, the sinusoidal current phase difference is 2π / 3, and the DC current is negative; the neutral points of the two sets of windings are connected to provide a path for zero-sequence current. When connecting the windings, the influence of the coil pitch coefficient and the distribution coefficient on the winding factor must be considered at the same time; The integrated winding (7) simultaneously carries both sinusoidal and direct current in its phase current, thus functioning as both an AC current winding and a DC current excitation winding; wherein, the number of magnetic field pole pairs P generated by the AC current of the winding is... a Designed as 1 or 2, the number of magnetic field pole pairs N generated by the DC current in the winding is... fw The number of pole pairs N of the main magnetic field generated by the permanent magnet pm To maintain consistency; the direction of the DC current flowing through the winding is determined according to the right-hand rule, and the direction of the magnetic field generated after the DC current flows through the winding is opposite to the magnetization direction of the permanent magnet (5) on the stator teeth (3) wound therein; and by changing the positive and negative of the DC current, the direction of the excitation magnetic field is adjusted to achieve the purpose of strengthening or weakening the air gap magnetic field.

4. The dual three-phase hybrid excitation motor structure as described in claim 1, characterized in that: Establish a permanent magnet (5) with a width θ pm Stator slot opening width θ sw Iron pole (4) width θ st The expression for the harmonics of permanent magnet excitation and DC current excitation magnetomotive force, i.e., F pm, m (θ pm , θ st , θ sw ) and F fw, n (θ pm , θ st , θ sw Based on this, the expression for the higher harmonic enhancement factor λ is established. pm, m and λ fw, n η represents the ratio of the working air gap magnetic flux density generated by the higher harmonic magnetomotive force of permanent magnet and DC current excitation to its fundamental magnetomotive force, respectively, used to measure the magnitude of higher harmonic enhancement; further, an expression η for the utilization rate of higher harmonic magnetomotive forces of permanent magnet excitation and DC current excitation magnetomotive forces is established. pm, m and η fw, n This reflects the magnitude of the torque enhancement capability of the higher harmonic design; With the width θ of the permanent magnet (5) pm Stator slot opening width θ sw Iron pole (4) width θ st Design variables to maximize η pm, m and η fw, n To optimize the objective, the maximum value of the objective is obtained, thereby determining the values ​​of the three design variables and the gear ratio. Furthermore, with the maximum torque as the optimization objective and fixed copper loss as a prerequisite, the other design variables are optimized to obtain the values ​​of the other design variables when the maximum torque is achieved.

5. A design method for a dual-three-phase hybrid excitation motor based on high-order harmonic utilization, the motor comprising a rotor consisting only of iron core salient poles and a stator with permanent magnets and integrated windings, characterized in that, The design method includes the following steps: The pole-slot matching relationship is determined so that the magnetic field generated by the permanent magnet is distributed in an NNSS-type array in space, and the magnetic field generated by the DC current flowing through the integrated winding is distributed in an SSNN-type array in space, so that both generate high-amplitude high-order harmonic magnetomotive force. Step 1: Establish the correspondence between the three structural parameters of the motor—the width of the permanent magnet, the width of the iron pole, and the width of the stator slot opening—and the amplitude of the higher harmonic magnetomotive force; Step 2: Based on the ratio of the higher harmonic magnetomotive force amplitude to the fundamental magnetomotive force amplitude, and the ratio of the gear ratio corresponding to the higher harmonic design to the gear ratio corresponding to the fundamental design, construct a higher harmonic utilization parameter to measure the torque enhancement capability of the higher harmonic design. The utilization parameter is defined for permanent magnet excitation and DC current excitation respectively. Step 3: With maximizing the high-order harmonic utilization rate parameter of the permanent magnet excitation and the high-order harmonic utilization rate parameter of the DC current excitation as the common optimization objectives, perform multi-objective optimization on the permanent magnet width, iron pole width, stator slot opening width and gear ratio, and determine the above parameter values ​​that make the two utilization rate parameters reach their maximum simultaneously. Step 4: Under the premise of fixed motor copper loss, with the optimization goal of maximizing motor output torque, optimize the other motor structural parameters except for the permanent magnet width, iron pole width, and stator slot opening width to obtain the optimal values ​​of the other structural parameters that maximize torque.

6. The design method according to claim 5, characterized in that, The correspondence in step one is established in the following way: Mathematical modeling and Fourier analysis were performed on the magnetomotive force waveforms generated by excitation of permanent magnets alone and by excitation of DC current from windings alone, respectively, to obtain the magnetomotive force harmonic amplitude expression with the width of the permanent magnet, the width of the iron pole, and the width of the stator slot opening as variables.

7. The design method according to claim 5, characterized in that, The multi-objective optimization in step three adopts the non-dominated sorting genetic algorithm II, and obtains the parameter solution set when the two higher harmonic utilization parameters are maximized simultaneously by generating a Pareto graph and based on the Pareto front.

8. The design method according to claim 5, characterized in that, In step four, before optimizing the remaining structural parameters, a sensitivity analysis method is introduced to distinguish the remaining structural parameters into insensitive parameters and sensitive parameters. The non-sensitive parameter is obtained by scanning a finite element model to obtain its optimal value that maximizes the torque; The sensitivity parameter is further obtained by combining the finite element model with the optimization algorithm to obtain the optimal value that maximizes the torque. The optimization process for the aforementioned sensitivity parameters specifically includes: Using the aforementioned sensitivity parameters as optimization variables, a sample database is generated through a central composite design method; Under the condition that the stator inner diameter, rotor outer diameter, effective shaft length, air gap length, permanent magnet width, iron pole width, and stator slot opening width determined in step three remain unchanged, and the copper loss is the same, the torque value corresponding to each sample in the sample database is obtained by using the finite element model. A high-precision regression equation is established based on curve fitting to characterize the relationship between the sensitive parameter and the torque; The regression equation is combined with the non-dominated sorting genetic algorithm II to construct an optimization model, and the optimal value of the sensitivity parameter that maximizes the torque is obtained by solving the problem.

9. The design method according to claim 8, characterized in that, The sensitive parameters include at least the following: the lower width of the rotor salient pole, the upper width of the rotor salient pole, the stator tooth width, the rotor yoke thickness, the stator slot height, and the permanent magnet thickness.

10. The design method according to claim 5, characterized in that, It also includes the winding design steps: The integrated winding is designed as a double three-phase winding, with each phase winding consisting of multiple coils connected in series, and adopts a double-layer distributed winding. In the first set of three-phase windings, each phase is supplied with a sinusoidal alternating current with a phase difference of 120 degrees and a positive direct current is superimposed; in the second set of three-phase windings, each phase is supplied with a sinusoidal alternating current with a phase difference of 120 degrees and a negative direct current is superimposed; the neutral points of the two sets of windings are connected to each other to provide a path for zero-sequence current.

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