A high-power-density double-stator permanent magnet synchronous motor optimization design method

Abstract

The application discloses a high-power-density double-stator permanent magnet synchronous motor optimization design method. The method comprises the following steps: determining the stator outer diameter of the double-stator permanent magnet synchronous motor and the inner and outer rotor magnetic circuit topology structure of the rotor; determining the final pole arc coefficient and the stator slot ratio of the outer motor under different pole arc coefficients and stator slot ratios of the outer motor according to the motor average torque, torque fluctuation and motor efficiency; keeping the total amount of permanent magnets unchanged, changing the pole arc coefficient ratio of N and S magnetic poles on the rotor; and determining the final pole arc coefficient ratio according to the change amount of the cogging torque, torque fluctuation and motor average torque under different pole arc coefficient ratios, so as to finally obtain the high-power-density double-stator permanent magnet synchronous motor. The double-stator permanent magnet synchronous motor is optimized and designed, the optimized magnetic pole structure can reduce the torque fluctuation of the motor while keeping high power density, and effectively improves the stability of motor operation.

Description

Technical Field

[0001] This invention relates to an optimization design method for permanent magnet synchronous motors, specifically an optimization design method for high power density dual-stator permanent magnet synchronous motors. Background Technology

[0002] With the continuous development of permanent magnet materials, the application fields of permanent magnet synchronous motors are constantly expanding. Compared with traditional electrically excited motors, rare-earth permanent magnet motors have significant advantages such as simple structure, reliable operation, small size, high efficiency, and flexible and diverse shapes. However, in some application areas, the space for motor placement is becoming increasingly limited, making high power density a hot topic in the development of permanent magnet motors. Dual-stator permanent magnet synchronous motors are widely used in high-power-density motors due to their high internal space utilization and ability to output higher torque within a given volume.

[0003] Dual-stator permanent magnet synchronous motors (PMSMs) have complex and diverse rotor magnetic circuit topologies. To improve the power density of the motor within a specific volume, the no-load and load characteristics of dual-stator PMSMs with different rotor magnetic circuit topologies can be compared under the same stator outer diameter to determine the rotor magnetic circuit topology with higher power density. Furthermore, the pole arc coefficient and stator split ratio have a certain influence on the electromagnetic performance of the motor and can further improve the power density.

[0004] However, permanent magnet synchronous motors suffer from significant torque ripple. The torque ripple in a dual-stator permanent magnet synchronous motor is caused by both the inner and outer motors, resulting in substantial torque fluctuations that are detrimental to smooth motor operation. Torque ripple includes cogging torque caused by changes in magnetic permeability due to stator slotting, and ripple torque generated by the interaction between the stator and rotor magnetic fields. Summary of the Invention

[0005] To address the problems existing in the background technology, this invention provides an optimized design method for a high power density dual-stator permanent magnet synchronous motor. It designs a rotor magnetic circuit topology for the high power density dual-stator permanent magnet synchronous motor, which can increase the motor's power density without changing the stator outer diameter. Simultaneously, a unequal pole arc coefficient magnetic pole structure is designed to reduce torque ripple by decreasing cogging torque, ensuring smooth motor operation.

[0006] The technical solution adopted in this invention is:

[0007] The optimized design method for a dual-stator permanent magnet synchronous motor of the present invention includes the following steps:

[0008] Step 1): Determine the stator outer diameter and the inner and outer rotor magnetic circuit topology of the dual-stator permanent magnet synchronous motor to obtain the first improved dual-stator permanent magnet synchronous motor.

[0009] Step 2): Drive the first improved dual-stator permanent magnet synchronous motor to run, change the pole arc coefficient of the first improved dual-stator permanent magnet synchronous motor and the stator split ratio of the external motor. Under different pole arc coefficients and stator split ratios of the external motor, determine the final pole arc coefficient and stator split ratio of the external motor based on the average torque, torque fluctuation and motor efficiency of the first improved dual-stator permanent magnet synchronous motor to obtain the second improved dual-stator permanent magnet synchronous motor.

[0010] Step 3): Drive the second improved dual-stator permanent magnet synchronous motor to run, keeping the total amount of permanent magnets in the second improved dual-stator permanent magnet synchronous motor unchanged, and change the ratio of the pole arc coefficients of the N and S poles on the rotor. Under different ratios of the pole arc coefficients of the N and S poles on the rotor, determine the final ratio of the pole arc coefficients based on the changes in the cogging torque, torque fluctuation and average torque of the second improved dual-stator permanent magnet synchronous motor, and finally obtain a high power density dual-stator permanent magnet synchronous motor.

[0011] In step 1), the stator outer diameter of the dual-stator permanent magnet synchronous motor is designed to be the same as that of the single-stator built-in permanent magnet synchronous motor.

[0012] In step 1), the inner rotor magnetic circuit topology of the dual-stator permanent magnet synchronous motor is designed as a surface-mounted series rotor magnetic circuit topology, and the outer rotor magnetic circuit topology is designed as a surface-mounted series rotor magnetic circuit structure.

[0013] In step 2), under different pole arc coefficients and stator split ratios of the external motor, the final pole arc coefficient and stator split ratio of the external motor are determined based on the average torque, torque fluctuation, and motor efficiency of the first improved dual-stator permanent magnet synchronous motor, as follows:

[0014] 2.1) Change the pole arc coefficient of the first improved dual-stator permanent magnet synchronous motor. When the average torque of the first improved dual-stator permanent magnet synchronous motor is high, the motor efficiency is high, and the torque fluctuation is low, select the pole arc coefficient at this time as the final pole arc coefficient.

[0015] 2.2) Change the stator split ratio of the outer motor of the first improved dual-stator permanent magnet synchronous motor, and the outer diameter of the inner motor will change accordingly. When the average torque, motor efficiency and torque fluctuation of the first improved dual-stator permanent magnet synchronous motor are high, the stator split ratio of the outer motor at this time is selected as the final stator split ratio of the outer motor, so as to obtain the second improved dual-stator permanent magnet synchronous motor.

[0016] In step 3), the ratio of the pole arc coefficients of the N and S magnetic poles on the rotor of the second improved dual-stator permanent magnet synchronous motor is changed. Specifically, the ratio of the pole arc coefficients of the N and S magnetic poles of the outer permanent magnet of the rotor of the second improved dual-stator permanent magnet synchronous motor is changed, or the ratio of the pole arc coefficients of the N and S magnetic poles of the inner and outer permanent magnets of the rotor is changed respectively.

[0017] In step 3), the final pole arc coefficient ratio is determined based on the cogging torque, torque fluctuation, and changes in the average torque of the second improved dual-stator permanent magnet synchronous motor, under different ratios of the pole arc coefficients of the N and S poles on the rotor, as detailed below:

[0018] By changing the ratio of the pole arc coefficients of the N and S magnetic poles on the rotor of the second improved dual-stator permanent magnet synchronous motor, when the cogging torque of the second improved dual-stator permanent magnet synchronous motor is low, the torque fluctuation is low, and the change in the average torque of the motor is small, the ratio of the pole arc coefficients of the N and S magnetic poles on the rotor at this time is selected as the final ratio of the pole arc coefficients of the N and S magnetic poles on the rotor, and finally a high power density dual-stator permanent magnet synchronous motor is obtained.

[0019] The beneficial effects of this invention are:

[0020] This invention designs a rotor magnetic circuit topology for a dual-stator permanent magnet synchronous motor, and a surface-mounted rotor series magnetic circuit dual-stator permanent magnet synchronous motor with high power density. The improved rotor magnetic circuit topology is optimized by adjusting the pole arc coefficient and stator split ratio to achieve higher power density. Furthermore, to address the issue of large torque fluctuations, an unequal pole arc coefficient magnetic pole structure is proposed. By reducing cogging torque, torque fluctuations are reduced, resulting in a high-power-density dual-stator permanent magnet synchronous motor with low torque fluctuations. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a single-stator permanent magnet synchronous motor.

[0022] Figure 2 The rotor magnetic circuit topology diagrams for eight types of dual-stator permanent magnet synchronous motors are shown.

[0023] Figure 3 (a) is a comparison diagram of the cogging torque of a dual-stator permanent magnet synchronous motor;

[0024] Figure 3 (b) is a comparison chart of the average torque of a dual-stator permanent magnet synchronous motor;

[0025] Figure 4 The output characteristics of a dual-stator permanent magnet synchronous motor vary with the pole arc coefficient α. PM Change diagram;

[0026] Figure 5The output characteristics of a dual-stator permanent magnet synchronous motor vary with the stator split ratio K. D Change diagram;

[0027] Figure 6 (a) is a schematic diagram of the structure of the unequal arc coefficient magnetic poles before the improvement;

[0028] Figure 6 (b) is a schematic diagram of the improved structure of the unequal pole arc coefficient magnetic pole;

[0029] Figure 7 (a) is a graph showing the variation of the cogging torque of motor III output characteristic with the Z value of the unequal pole arc coefficient;

[0030] Figure 7 (b) is a graph showing the variation of the average torque of the output characteristic of motor III with the value of the unequal pole arc coefficient Z;

[0031] Figure 7 (c) is a graph showing the variation of the output characteristic torque fluctuation of motor III with the Z value of the unequal pole arc coefficient;

[0032] Figure 7 (d) is a graph showing the variation of the unbalanced magnetic pull force of motor III output characteristics with the Z value of the unequal pole arc coefficient;

[0033] Figure 8 A comparison chart of torque before and after motor optimization. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] The optimized design method for a dual-stator permanent magnet synchronous motor of the present invention includes the following steps:

[0036] Step 1): Determine the stator outer diameter and the inner and outer rotor magnetic circuit topology of the dual-stator permanent magnet synchronous motor to obtain the first improved dual-stator permanent magnet synchronous motor.

[0037] In step 1), the stator outer diameter of the dual-stator permanent magnet synchronous motor is designed to be the same as that of the single-stator built-in permanent magnet synchronous motor.

[0038] In step 1), the inner rotor magnetic circuit topology of the dual-stator permanent magnet synchronous motor is designed as a surface-mounted series rotor magnetic circuit topology, and the outer rotor magnetic circuit topology is designed as a surface-mounted series rotor magnetic circuit structure.

[0039] Step 2): Drive the first improved dual-stator permanent magnet synchronous motor to run, change the pole arc coefficient of the first improved dual-stator permanent magnet synchronous motor and the stator split ratio of the external motor. Under different pole arc coefficients and stator split ratios of the external motor, determine the final pole arc coefficient and stator split ratio of the external motor based on the average torque, torque fluctuation and motor efficiency of the first improved dual-stator permanent magnet synchronous motor to obtain the second improved dual-stator permanent magnet synchronous motor.

[0040] In step 2), under different pole arc coefficients and stator split ratios of the external motor, the final pole arc coefficient and stator split ratio of the external motor are determined based on the average torque, torque fluctuation, and motor efficiency of the first improved dual-stator permanent magnet synchronous motor, as follows:

[0041] 2.1) Change the pole arc coefficient of the first improved dual-stator permanent magnet synchronous motor. When the average torque of the first improved dual-stator permanent magnet synchronous motor is high, the motor efficiency is high, and the torque fluctuation is low, select the pole arc coefficient at this time as the final pole arc coefficient.

[0042] 2.2) Change the stator split ratio of the outer motor of the first improved dual-stator permanent magnet synchronous motor, and the outer diameter of the inner motor will change accordingly. When the average torque, motor efficiency and torque fluctuation of the first improved dual-stator permanent magnet synchronous motor are high, the stator split ratio of the outer motor at this time is selected as the final stator split ratio of the outer motor, so as to obtain the second improved dual-stator permanent magnet synchronous motor.

[0043] Step 3): Drive the second improved dual-stator permanent magnet synchronous motor to run, keeping the total amount of permanent magnets in the second improved dual-stator permanent magnet synchronous motor unchanged, and change the ratio of the pole arc coefficients of the N and S poles on the rotor. Under different ratios of the pole arc coefficients of the N and S poles on the rotor, determine the final ratio of the pole arc coefficients based on the changes in the cogging torque, torque fluctuation and average torque of the second improved dual-stator permanent magnet synchronous motor, and finally obtain a high power density dual-stator permanent magnet synchronous motor.

[0044] In step 3), the ratio of the pole arc coefficients of the N and S magnetic poles on the rotor of the second improved dual-stator permanent magnet synchronous motor is changed. Specifically, the ratio of the pole arc coefficients of the N and S magnetic poles of the outer permanent magnet of the rotor of the second improved dual-stator permanent magnet synchronous motor is changed, or the ratio of the pole arc coefficients of the N and S magnetic poles of the inner and outer permanent magnets of the rotor is changed respectively.

[0045] In step 3), the final pole arc coefficient ratio is determined based on the cogging torque, torque fluctuation, and changes in the average torque of the second improved dual-stator permanent magnet synchronous motor under different ratios of the pole arc coefficients of the N and S poles on the rotor, as follows:

[0046] By changing the ratio of the pole arc coefficients of the N and S magnetic poles on the rotor of the second improved dual-stator permanent magnet synchronous motor, when the cogging torque of the second improved dual-stator permanent magnet synchronous motor is low, the torque fluctuation is low, and the change in the average torque of the motor is small, the ratio of the pole arc coefficients of the N and S magnetic poles on the rotor at this time is selected as the final ratio of the pole arc coefficients of the N and S magnetic poles on the rotor, and finally a high power density dual-stator permanent magnet synchronous motor is obtained.

[0047] Specific embodiments of the present invention are as follows:

[0048] The following describes the implementation of the present invention in detail with reference to a single-stator 8-pole 48-slot built-in permanent magnet synchronous motor. The initial structure of the single-stator built-in permanent magnet synchronous motor is as follows: Figure 1 As shown in Table 1, the parameters of the motor are as follows.

[0049] Table 1 Single Stator IPMSM Parameters

[0050] parameter symbol numerical values unit Rated speed <![CDATA[n N ]]> 3000 r / min Rated torque <![CDATA[T N ]]> 64 Nm Extreme logarithm P 4 -- Number of slots Q 48 -- Stator outer diameter <![CDATA[D o ]]> 200 mm Stator inner diameter <![CDATA[D i ]]> 130 mm Air gap length δ 1 mm Core length l 140 mm Rated current I 93.5 A Rated power <![CDATA[P N ]]> 20 kW

[0051] Step 1): Determine the stator outer diameter of the dual-stator permanent magnet synchronous motor, and then determine the inner and outer rotor magnetic circuit topology. Before determining the rotor magnetic circuit topology of the dual-stator permanent magnet synchronous motor, eight rotor magnetic circuit topologies for dual-stator permanent magnet synchronous motors were first selected, such as... Figure 2 As shown, the rotor magnetic circuit topologies of the eight types of dual-stator permanent magnet synchronous motors are as follows: Motor I: "U"-shaped series rotor magnetic circuit structure; Motor II: "V"-shaped + surface-mounted series rotor magnetic circuit structure; Motor III: surface-mounted + surface-mounted series rotor magnetic circuit structure; Motor IV: embedded + embedded series rotor magnetic circuit structure; Motor V: "U"-shaped + surface-mounted parallel rotor magnetic circuit structure; Motor VII: spoke-type parallel rotor magnetic circuit structure; Motor VI: surface-mounted + surface-mounted parallel rotor magnetic circuit structure; Motor VIII: embedded + embedded parallel rotor magnetic circuit structure.

[0052] No-load and load characteristics of dual-stator permanent magnet synchronous motors with eight different rotor magnetic circuit topologies were analyzed to determine the rotor magnetic circuit topology with higher power density. The specific operation steps are as follows:

[0053] Keeping the inner and outer diameters of the motor stator unchanged, the rotor is modified to a cup-shaped structure, with an additional inner stator structure added inside. Design analysis is performed on eight types of dual-stator permanent magnet synchronous motors with different rotor magnetic circuit topologies. The first four motors use a series magnetic circuit structure, while the latter four use a parallel magnetic circuit structure. Specific motor parameters are shown in Table 2.

[0054] Table 2 Basic Parameters of Dual-Stator Permanent Magnet Synchronous Motor

[0055]

[0056]

[0057] No-load and load analyses were performed on eight different rotor magnetic circuit topologies of dual-stator permanent magnet synchronous motors, and the comparisons of their cogging torque and average torque were obtained. Figure 3 As shown in (a) and (b), the performance comparison of dual-stator permanent magnet synchronous motors with different rotor magnetic circuit topologies is shown in Table 3. It can be seen from the table that the motor efficiency changes very little. Motor III shows the largest increase in average torque, T = 86.9 Nm, which is 35.8% higher than the single-stator built-in permanent magnet synchronous motor. Therefore, the rotor magnetic circuit topology corresponding to Motor III is selected to obtain the first improved dual-stator permanent magnet synchronous motor.

[0058] Table 3 Performance Comparison of DS-PMSM with Different Rotor Magnetic Circuit Topologies

[0059]

[0060] Step 2): Optimize the pole arc coefficient and stator split ratio of the selected motor III to further improve the power density. The specific operation steps are as follows:

[0061] 2.1) The output torque of a permanent magnet synchronous motor is proportional to the amplitude of the air gap magnetic flux density. Changing the pole arc coefficient of the rotor magnetic pole will change the amplitude of the air gap magnetic flux density of the motor. Therefore, changing the pole arc coefficient has a certain impact on its output torque.

[0062] For the polar arc coefficient α p The definition of is:

[0063]

[0064] Where, α PM Let τ be the angle occupied by the permanent magnet at one pole pitch, and τ be the angle occupied by the pole pitch.

[0065] Changing the polar arc coefficient α p The relationship between motor output characteristics and pole arc coefficient is as follows: Figure 4 As shown. To achieve a higher power density, and considering the impact of increased pole arc coefficient on motor torque ripple and efficiency, motor III is selected with α. p =0.95. At this point, the average torque is 89.8 Nm, which is 40.3% higher than that of a single-stator built-in permanent magnet synchronous motor.

[0066] 2.2) The torque of a dual-stator permanent magnet synchronous motor can be considered as the sum of the electromagnetic torques of the inner and outer motors. The ratio of the inner and outer motors directly affects its output torque. The formulas for calculating the inner and outer diameters of the inner and outer stators of a dual-stator permanent magnet synchronous motor are defined as follows:

[0067]

[0068] D i2-out =D i1-in -2(h jr +h m-in +h m-out +g1+g2)

[0069] Among them, K D For the stator split ratio of the external motor, D i1-out D is the outer diameter of the outer stator. i1-in D is the inner diameter of the outer stator. i2-out h is the outer diameter of the inner stator. jr h is the rotor yoke thickness. m-in and h m-out g1 and g2 are the thicknesses of the permanent magnets inside and outside the rotor, respectively, and g1 and g2 are the lengths of the air gaps inside and outside the rotor, respectively.

[0070] The relationship between the electromagnetic torque and stator split ratio T of the DS-PMSM is derived. total for:

[0071]

[0072] Where Q is the number of stator slots; a is the number of parallel branches; K w L is the winding coefficient; Fe N is the length of the iron core. s1 With N s2 These represent the number of conductors per slot for the external and internal motors, respectively; I1 and I2 are the effective values ​​of the phase currents for the external and internal motors, respectively; B δ1 With B δ2 These are the air gap magnetic flux density fundamental wave amplitudes of the external and internal motors, respectively; h is h jr h m-in h m-out The sum of g1 and g2.

[0073] From the above formula, it can be seen that the external motor stator split ratio K D This affects the output torque of a dual-stator permanent magnet synchronous motor. Keeping the outer stator outer diameter constant, changing the outer stator segment ratio will correspondingly change the inner stator segment ratio. For example... Figure 5 The figure shows the electromagnetic performance variation curves of a dual-stator permanent magnet synchronous motor under different external stator split ratios. At an external stator split ratio K... D When the torque is 0.75, the motor can obtain a large torque, T = 104.4 Nm, with a torque fluctuation of 7.6%. However, the torque fluctuation of the motor is relatively large at this point and needs to be further reduced.

[0074] Step 3): Optimize the motor using the rotor's unequal pole arc coefficient structure. The specific steps are as follows:

[0075] 3.1) The rotor pole structure of the traditional permanent magnet synchronous motor and the proposed unequal pole arc coefficient pole structure are as follows: Figure 6 As shown in (a) and (b), the pole arc angles corresponding to the N and S poles under each pair of poles in the rotor magnetic pole structure with unequal pole arc coefficients satisfy the following conditions:

[0076]

[0077] θ b =Zθ a

[0078] Where, θ a With θ b These are the polar arc angles corresponding to each pair of subpolar PM1 and PM2; α p denoted by , p is the pole arc coefficient; p is the number of pole pairs; Z is the pole arc ratio. When Z = 1, the pole arc coefficients of all magnetic blocks are the same, which is a traditional surface-mount magnetic pole structure. When Z ≠ 1, it is a magnetic pole structure with unequal pole arc coefficients.

[0079] 3.2) The dual-stator permanent magnet synchronous motor with the unequal pole arc ratio Z of the external single-layer magnet of the dual stator is named motor III-1, and the dual-stator permanent magnet synchronous motor with the unequal pole arc ratio Z of the inner and outer double-layer magnets is named motor III-2. Simulation comparison analysis is performed on them.

[0080] Analysis of the output characteristics of a dual-stator permanent magnet synchronous motor at different Z values ​​using finite element method software, such as... Figure 7 As shown in (a), (b), (c), and (d), motor III-1 has the smallest cogging torque value and the lowest torque fluctuation value of 2.6% when Z = 0.8; motor III-2 has the smallest cogging torque value and the lowest torque fluctuation value of 2.2% when Z = 1.6. When Z = 0.9, the torque fluctuation of motor III-1 is 3.7%, and the average torque is 103.4 Nm; the torque fluctuation of motor III-2 is 3.2%, and the average torque is 103.8 Nm. The curves of unbalanced magnetic pull change of motors under different Z values ​​are shown below. Figure 7 As shown in (d), the overall unbalanced magnetic pull of the motor fluctuates around 6N, with little impact. Considering the influence on the motor torque and power density, a unequal pole arc coefficient ratio of Z = 0.9 is appropriate. Table 4 shows a comparison of the output characteristics of motor III before and after rotor magnetic pole optimization at Z = 0.9.

[0081] Table 4 Comparison of output characteristics before and after optimization of rotor magnetic pole structure of Motor III

[0082]

[0083] 3.3) Based on the above steps, the final high-power-density dual-stator permanent magnet synchronous motor was obtained. Finite element simulations were performed to compare it with the unoptimized Motor III and the initial single-stator permanent magnet synchronous motor. The results are as follows: Figure 8 As shown in the figure. The results show that the torque of this motor is 62.2% higher than that of the single-stator built-in permanent magnet synchronous motor, and the torque fluctuation is 57.9% lower than that of motor III. The power density of this motor is significantly improved, while the torque fluctuation is significantly reduced, making the motor operation more stable.

Claims

1. An optimized design method for a high power density dual-stator permanent magnet synchronous motor, characterized in that: The method includes the following steps: Step 1): Determine the stator outer diameter and the inner and outer rotor magnetic circuit topology of the dual-stator permanent magnet synchronous motor to obtain the first improved dual-stator permanent magnet synchronous motor. Step 2): Drive the first improved dual-stator permanent magnet synchronous motor to run, change the pole arc coefficient of the first improved dual-stator permanent magnet synchronous motor and the stator split ratio of the external motor. Under different pole arc coefficients and stator split ratios of the external motor, determine the final pole arc coefficient and stator split ratio of the external motor based on the average torque, torque fluctuation and motor efficiency of the first improved dual-stator permanent magnet synchronous motor to obtain the second improved dual-stator permanent magnet synchronous motor. Step 3): Drive the second improved dual-stator permanent magnet synchronous motor to run, keep the total amount of permanent magnets in the second improved dual-stator permanent magnet synchronous motor unchanged, change the ratio of the pole arc coefficients of the N and S poles on the rotor, and determine the final pole arc coefficient ratio based on the cogging torque, torque fluctuation and the change of the average torque of the second improved dual-stator permanent magnet synchronous motor under different ratios of the pole arc coefficients of the N and S poles on the rotor, and finally obtain a high power density dual-stator permanent magnet synchronous motor; In step 3), the ratio of the pole arc coefficients of the N and S magnetic poles on the rotor of the second improved dual-stator permanent magnet synchronous motor is changed. Specifically, the ratio of the pole arc coefficients of the N and S magnetic poles of the outer permanent magnet of the rotor of the second improved dual-stator permanent magnet synchronous motor is changed, or the ratio of the pole arc coefficients of the N and S magnetic poles of the inner and outer permanent magnets of the rotor is changed respectively.

2. The optimized design method for a high power density dual-stator permanent magnet synchronous motor according to claim 1, characterized in that: In step 1), the stator outer diameter of the dual-stator permanent magnet synchronous motor is designed to be the same as that of the single-stator built-in permanent magnet synchronous motor.

3. The optimized design method for a high power density dual-stator permanent magnet synchronous motor according to claim 1, characterized in that: In step 1), the inner rotor magnetic circuit topology of the dual-stator permanent magnet synchronous motor is designed as a surface-mounted series rotor magnetic circuit topology, and the outer rotor magnetic circuit topology is designed as a surface-mounted series rotor magnetic circuit structure.

4. The optimized design method for a high power density dual-stator permanent magnet synchronous motor according to claim 1, characterized in that: In step 2), under different pole arc coefficients and stator split ratios of the external motor, the final pole arc coefficient and stator split ratio of the external motor are determined based on the average torque, torque fluctuation, and motor efficiency of the first improved dual-stator permanent magnet synchronous motor, as follows: 2.1) Change the pole arc coefficient of the first improved dual-stator permanent magnet synchronous motor. When the average torque of the first improved dual-stator permanent magnet synchronous motor is high, the motor efficiency is high, and the torque fluctuation is low, select the pole arc coefficient at this time as the final pole arc coefficient. 2.2) Change the stator split ratio of the external motor of the first improved dual-stator permanent magnet synchronous motor. When the average torque of the first improved dual-stator permanent magnet synchronous motor is high, the motor efficiency is high, and the torque fluctuation is low, select the stator split ratio of the external motor at this time as the final stator split ratio of the external motor, thereby obtaining the second improved dual-stator permanent magnet synchronous motor.

5. The optimized design method for a high power density dual-stator permanent magnet synchronous motor according to claim 1, characterized in that: In step 3), the final pole arc coefficient ratio is determined based on the cogging torque, torque fluctuation, and changes in the average torque of the second improved dual-stator permanent magnet synchronous motor, under different ratios of the pole arc coefficients of the N and S poles on the rotor, as detailed below: By changing the ratio of the pole arc coefficients of the N and S magnetic poles on the rotor of the second improved dual-stator permanent magnet synchronous motor, when the cogging torque of the second improved dual-stator permanent magnet synchronous motor is low, the torque fluctuation is low, and the change in the average torque of the motor is small, the ratio of the pole arc coefficients of the N and S magnetic poles on the rotor at this time is selected as the final ratio of the pole arc coefficients of the N and S magnetic poles on the rotor, and finally a high power density dual-stator permanent magnet synchronous motor is obtained.

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