Rotor and optimization method for optimizing NVH performance of electric vehicles

Abstract

The present invention discloses a rotor for optimizing the NVH performance of electric vehicles and an optimization method thereof. The shape of the magnetic barrier of the motor rotor punching is optimized to change the rotor structure. On the basis of not increasing the difficulty of rotor processing, the harmonic content of the motor radial magnetic flux density is improved, the torque pulsation is reduced, the average torque is increased, and the motor drive quality is improved. At the same time, the lower pulsating torque can reduce the knocking noise between the gear meshing of the powertrain, thereby achieving the purpose of optimizing the NVH performance of electric vehicles. A complete optimization simulation process is provided to test the NVH performance of electric vehicles using structurally optimized rotors, reducing the difficulty and cost of optimizing the rotor structure through experimental methods, and improving the efficiency of optimizing NVH. The method also obtains vibration noise under multiple working conditions by parameterizing the motor speed, thereby improving the reliability of optimization.

Description

Technical Field

[0001] The present invention belongs to the field of electric vehicle rotor design, and in particular relates to a rotor for optimizing the NVH performance of an electric vehicle and an optimization method thereof. Background Art

[0002] Due to the influence of the harsh climate environment, the international community has paid more and more attention to environmental protection issues. Electric vehicles are also favored by many car companies due to their unique environmental advantages. At the same time, the supporting infrastructure of electric vehicles has been continuously improved in recent years, and electric vehicles have become more and more popular. Excellent NVH performance can stand out among many electric vehicles and be more competitive. The powertrain is the driving source of electric vehicles, and the NVH performance of the powertrain plays a decisive role in the NVH performance of the entire vehicle. Therefore, it is necessary to study the optimization of the NVH performance of the powertrain of electric vehicles.

[0003] At present, in order to improve the range of electric vehicles and reduce people's range anxiety, car companies have integrated the design of the original drive system to save space in the vehicle and reduce the weight to install batteries with higher range. Compared with traditional fuel vehicles, the overall sound pressure level of electric vehicle powertrain is significantly lower, and it has better NVH performance, but high-frequency electromagnetic noise can easily cause mental fatigue and emotional irritability of people in the car. The main vibration noise of the powertrain is the electromagnetic noise of the motor. Therefore, improving the rotor structure of the motor and reducing electromagnetic noise can achieve the purpose of optimizing NVH performance. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention proposes a rotor structure and an optimization method for optimizing the NVH performance of electric vehicles, improves the existing motor rotor structure, and optimizes the NVH performance of electric vehicles; and establishes an optimization analysis system to further optimize the rotor structure according to the noise waterfall diagram at each speed.

[0005] The rotor used to optimize the NVH performance of electric vehicles is composed of X rotor punchings stacked and reinforced with adhesive. A circular motor shaft mounting hole is set in the center of each rotor punching, and 2P magnetic poles are set on the outside of the mounting hole. Each magnetic pole consists of three permanent magnets and is distributed in two layers. The side close to the motor shaft mounting hole is called the inner magnetic pole, and the side away is called the outer magnetic pole.

[0006] The magnetic barrier holes of the rotor are also distributed in two layers, among which the inner magnetic barrier holes close to the motor shaft mounting hole are double "human" shaped structures, and the angle between them and the magnetic pole is M, and the value range of M is 110°~113°. The outer magnetic barrier holes far away from the motor shaft mounting hole are in the shape of "I". The rectangular outer magnetic barrier holes are improved. After the improvement, the angle N between the inner edge and the side edge of the outer magnetic barrier holes ranges from 90°~150°, and the length range of the side edge is 3~4.5mm; the side edge and the outer edge are connected by a line segment with an arc at the end, the radius range of the arc is 0.3~0.4mm, the center angle of the arc connecting the side edge is 79°, and the center angle of the arc connecting the outer edge is 91°.

[0007] Preferably, an auxiliary arc groove is constructed on the outside of the rotor punching, and a regular 2P polygon is established with the center of the rotor as the center point, so that the polygon is circumscribed to the outer contour of the rotor punching. With the vertex of the regular 2P polygon as the center, an auxiliary circle with a radius R is constructed and superimposed on the rotor contour, and the overlapping part of the two is removed to obtain the auxiliary arc groove of the rotor punching. The radius R of the auxiliary circle varies in the range of 5 to 7 mm.

[0008] The magnetic poles, magnetic barrier holes and auxiliary arc slots are evenly distributed around the center of the rotor, and the permanent magnet material is ensured to remain unchanged before and after optimization.

[0009] The rotor optimization method for optimizing the NVH performance of electric vehicles specifically includes the following steps:

[0010] Step 1: Establish an electromagnetic model of the permanent magnet synchronous motor of the powertrain, parameterize the motor speed, and obtain the radial electromagnetic force at each speed.

[0011] Step 2: Establish the outer shell of the powertrain and analyze the natural modes of the powertrain.

[0012] Step 3: Conduct coupling analysis on the electromagnetic and structural models established in Steps 1 and 2 to obtain the vibration response of the powertrain housing. After processing the vibration response results, output the noise waterfall diagram of the powertrain housing surface at each speed.

[0013] Step 4: Use the powertrain surface vibration obtained in step 3 as the excitation source to perform acoustic radiation analysis, establish an air sphere, simulate the propagation of noise in the air, and obtain a noise waterfall diagram of the air domain surface radiation.

[0014] Step 5. Identify the noise distribution and the sound pressure level at each speed through the noise waterfall diagram obtained in step 4 to determine whether the current rotor structure meets the requirements for optimizing NVH performance. If it does, output the current rotor structure. If not, return to step 1, adjust the permanent magnet synchronous motor rotor structure, and import the improved rotor structure into the new electromagnetic model.

[0015] The present invention has the following beneficial effects:

[0016] 1. By optimizing the magnetic barrier of the motor rotor punching to change the rotor structure, the harmonic content of the motor radial magnetic flux density is improved without increasing the difficulty of rotor processing, the torque pulsation is reduced, the average torque is increased, and the motor drive quality is improved. At the same time, the lower pulsating torque can reduce the knocking noise between the powertrain gear meshing, thereby achieving the purpose of optimizing the NVH performance of electric vehicles.

[0017] 2. By modeling and simulating the vibration and noise of the electric vehicle powertrain, a complete optimization simulation process is provided, which reduces the difficulty and cost of optimizing the rotor structure through experimental methods and improves the efficiency of optimizing NVH.

[0018] 3. In the process of optimizing the rotor structure, the motor speed is parameterized to analyze the vibration and noise of the powertrain under multiple working conditions. The powertrain noise can be considered and optimized under all working conditions, thereby improving the reliability of optimizing NVH performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Optimize the flow chart for powertrain NVH performance;

[0020] Figure 2 This is a schematic diagram of the original electric vehicle powertrain motor rotor punching structure;

[0021] Figure 3 It is a schematic diagram of the output torque of the motor of the original electric vehicle powertrain;

[0022] Figure 4 This is a schematic diagram of radial magnetic flux density of the original electric vehicle powertrain motor;

[0023] Figure 5 This is a schematic diagram of the finite element structure of an electric vehicle powertrain;

[0024] Figure 6 It is the equivalent noise waterfall diagram of the original electric vehicle powertrain surface;

[0025] Figure 7 This is the waterfall diagram of the equivalent noise in the far sound field of the original electric vehicle powertrain;

[0026] Figure 8 This is a schematic diagram of the optimized powertrain permanent magnet synchronous motor rotor punching structure;

[0027] Fig. 9 This is the output diagram of the optimized electric vehicle powertrain motor torque;

[0028] Fig.10 This is a schematic diagram of the radial magnetic flux density of the optimized electric vehicle powertrain motor;

[0029] Fig.11 The equivalent noise waterfall diagram of the optimized electric vehicle powertrain surface;

[0030] Fig.12 This is the waterfall diagram of the equivalent noise in the far sound field of the optimized electric vehicle powertrain; DETAILED DESCRIPTION

[0031] The present invention will be further explained below with reference to the accompanying drawings;

[0032] like Figure 1 As shown, the rotor optimization method for optimizing the NVH performance of electric vehicles specifically includes the following steps:

[0033] Step 1: Establish an electromagnetic model of the permanent magnet synchronous motor of the powertrain, parameterize the motor speed, and obtain the radial electromagnetic force at each speed.

[0034] The rotor structure of the permanent magnet synchronous motor is as follows: Figure 2 As shown, X rotor punchings are laminated and reinforced with adhesive. A circular motor shaft mounting hole is set in the center of each rotor punching, and eight magnetic poles are set on the outside of the mounting hole. Each magnetic pole is composed of three permanent magnets and distributed in two layers. The side close to the motor shaft mounting hole is called the inner magnetic pole, and the side away is called the outer magnetic pole.

[0035] The magnetic barrier holes of the rotor are also distributed in two layers, among which the inner magnetic barrier holes close to the motor shaft mounting hole are double "human" shaped structures, and the angle M with the magnetic pole is 110°. The outer magnetic barrier holes far away from the motor shaft mounting hole are in a "one" shaped structure. The rectangular outer magnetic barrier holes are improved. After the improvement, the angle N between the inner edge and the side edge of the outer magnetic barrier holes is 113°, and the length of the side edge ranges from 3 to 4.5mm; the side edge and the outer edge are connected by a line segment with an arc at the end, the radius of the arc is 0.3mm, the center angle of the arc connecting the side edge is 79°, and the center angle of the arc connecting the outer edge is 91°.

[0036] The magnetic poles, magnetic barrier holes and auxiliary arc slots are evenly distributed around the center of the rotor, and the permanent magnet material is ensured to remain unchanged before and after optimization.

[0037] The schematic diagram of the motor output torque and radial magnetic flux density is as follows: Figure 3 , Figure 4 shown.

[0038] Step 2: Build the outer shell of the powertrain, including the motor stator, motor housing, motor end cover, reducer housing, and reducer end cover. Figure 5 As shown, the natural modes of the powertrain are analyzed.

[0039] Step 3: Conduct coupling analysis on the electromagnetic and structural models established in steps 1 and 2 to obtain the vibration response of the powertrain housing. After processing the vibration response results, output the noise waterfall diagram of the powertrain housing surface at each speed, such as Figure 6 shown.

[0040] Step 4: Use the powertrain surface vibration obtained in step 3 as the excitation source to perform acoustic radiation analysis, establish an air sphere, simulate the propagation of noise in the air, and obtain the noise waterfall diagram of the air domain surface radiation, such as Figure 7 shown.

[0041] Step 5: Identify the noise distribution and the sound pressure level at each speed by using the noise waterfall diagram obtained in step 4. The noise is more serious at 1625-2500rpm and 5500-6000rpm. Figure 8 As shown, the angle M between the magnetic barrier hole on the inner side of the rotor punching and the magnetic pole is adjusted to 113° and the angle N between the inner edge and the side edge of the magnetic barrier hole on the outer layer of the rotor punching is adjusted to 145°. An auxiliary arc groove is constructed on the outer side of the rotor punching, and a regular octagon is established with the center of the rotor circle as the center point, so that the polygon is circumscribed to the outer contour of the rotor punching. With the vertex of the regular octagon as the center, an auxiliary circle with a radius R of 5.5 mm is constructed and superimposed on the rotor contour, and the overlapping part of the two is removed to obtain the auxiliary arc groove of the rotor punching. The adjusted rotor structure is imported into the electromagnetic model of the synchronous motor, and the new simulation results are output, such as Figure 9-12 The diagrams are as follows, which are the optimized electric vehicle powertrain motor torque output diagram, radial magnetic flux diagram, surface equivalent noise waterfall diagram and far-field equivalent noise waterfall diagram. The peak noise of the optimized rotor at 1625-2500rpm and 5500-6000rpm is reduced by 6dB, indicating that the rotor can optimize the powertrain NVH performance.

Claims

1. A rotor for optimizing the NVH performance of electric vehicles, which is composed of X rotor punchings laminated and reinforced with adhesive, and a circular motor shaft mounting hole is set in the center of each rotor punching, characterized in that: There are 2P magnetic poles on the outside of the motor shaft mounting hole. Each magnetic pole is composed of three permanent magnets and is distributed in two layers. The side close to the motor shaft mounting hole is called the inner magnetic pole, and the side far away is called the outer magnetic pole. The magnetic barrier holes of the rotor are also distributed in two layers, among which the inner magnetic barrier holes close to the motor shaft mounting hole are double "human" shaped structures, and the angle between them and the magnetic pole is M, and the value range of M is 110°~113°; the outer magnetic barrier holes far away from the motor shaft mounting hole are "I" shaped structures; the rectangular outer magnetic barrier holes are improved, and the value range of the angle N between the inner edge and the side edge of the improved outer magnetic barrier holes is 90°~150°, and the length range of the side edge is 3~4.5mm; the side edge and the outer edge are connected by a line segment with an arc at the end, the radius range of the arc is 0.3~0.4mm, the center angle of the arc connecting the side edge is 79°, and the center angle of the arc connecting the outer edge is 91°; The magnetic poles, magnetic barrier holes and auxiliary arc slots are evenly distributed around the center of the rotor, and the permanent magnet material before and after optimization is ensured to remain unchanged; An auxiliary arc groove is constructed on the outside of the rotor punching, and a regular 2P polygon is established with the center of the rotor as the center point, so that the polygon is circumscribed to the outer contour of the rotor punching. With the vertex of the regular 2P polygon as the center, an auxiliary circle with a radius of R is constructed and superimposed on the rotor contour, and the overlapping part of the two is removed to obtain the auxiliary arc groove of the rotor punching. The radius R of the auxiliary circle varies in the range of 5 to 7 mm.

2. The method for optimizing the rotor of an electric vehicle for optimizing NVH performance according to claim 1, characterized in that: The specific steps include: Step 1: Establish an electromagnetic model of the permanent magnet synchronous motor of the powertrain, parameterize the motor speed, and obtain the radial electromagnetic force at each speed; Step 2: Establish the outer shell of the powertrain and analyze the natural modes of the powertrain; Step 3: Conduct coupling analysis on the electromagnetic and structural models established in Step 1 and Step 2 to obtain the vibration response of the powertrain housing; after processing the vibration response results, output a noise waterfall diagram of the powertrain housing surface at each speed; Step 4: Use the surface vibration of the powertrain obtained in step 3 as an excitation source to perform acoustic radiation analysis, establish an air sphere, simulate the propagation of noise in the air, and obtain a noise waterfall diagram of the surface radiation of the air domain; Step 5. Identify the noise distribution and the sound pressure level at each speed through the noise waterfall diagram obtained in step 4 to determine whether the current rotor structure meets the requirements for optimizing NVH performance. If it does, output the current rotor structure. If not, return to step 1, adjust the permanent magnet synchronous motor rotor structure, and import the improved rotor structure into the new electromagnetic model.

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