End face reluctance compensator for permanent magnet synchronous motor pole-slot combination in automotive steering system

Abstract

This utility model discloses an end-face reluctance compensator for a permanent magnet synchronous motor pole-slot combination in an automotive steering system. It includes a moving end piece and a stationary end piece made of soft magnetic material. The moving end piece is welded to the rotor end and has evenly spaced first protrusions on its outer periphery, providing a low reluctance channel for end leakage flux. The weld joint also serves as a dynamic balance weight. The stationary end piece is fixed to the rear end cover of the motor and has evenly spaced second protrusions on its outer periphery, which cooperate with the moving end piece to form a low reluctance leakage flux path. A fixed air gap exists between the two protrusion groups, and a circumferential phase difference is provided. When the moving end piece rotates with the rotor, the relative motion of the protrusion groups generates reluctance modulation, changing the end magnetic circuit distribution to weaken cogging torque. This device has a simple structure, low cost, and is suitable for compact motor designs, improving motor reliability and operational stability. It can achieve cogging torque reduction, end leakage flux reduction, and rotor dynamic balance adjustment.

Description

Technical Field

[0001] This utility model relates to the field of permanent magnet synchronous motor technology for electric power steering systems, and specifically to an end face magnetic reluctance compensator for the pole-slot combination of a permanent magnet synchronous motor in an automotive steering system. Background Technology

[0002] The design of permanent magnet synchronous motors (PMSMs) in modern electric power steering systems is becoming increasingly compact, making the end bearings susceptible to magnetization and reducing generator reliability. The rotor dynamic balance, combined with the inherent cogging and friction torques of the PMSM, easily leads to vibration and noise. Existing methods to address rotor dynamic balance issues (such as improving machining accuracy), to address end bearing magnetization (such as using magnetic shields and ceramic bearings), and to optimize cogging torque (such as skewed poles, additional magnetic rings, or active control), all suffer from structural complexity, high cost, or limitations in manufacturing processes. Therefore, there is an urgent need for an end-face reluctance compensator with a pole-slot combination for permanent magnet synchronous motors in automotive steering systems. Utility Model Content

[0003] To address the shortcomings of existing technologies, this utility model provides an end-face reluctance compensator for a permanent magnet synchronous motor pole-slot combination in an automotive steering system.

[0004] This utility model discloses an end-face reluctance compensator for a permanent magnet synchronous motor pole-slot combination in an automotive steering system, comprising:

[0005] A soft magnetic material moving end piece is used to provide a low magnetic resistance channel for leakage magnetic flux at the end of the motor rotor. It is welded and fixed to the end of the motor rotor. Several first protrusions are evenly spaced along the circumferential direction on its outer periphery. Several first protrusions constitute a moving end piece protrusion group.

[0006] The stationary end piece, together with the soft magnetic material moving end piece, forms a low magnetic resistance path for leakage magnetic flux at the end of the motor rotor; it is fixed on the side of the rear end cover of the motor facing the soft magnetic material moving end piece, and a number of second protrusions are evenly spaced along the circumferential direction on its outer periphery, and the number of second protrusions constitutes the stationary end piece protrusion group.

[0007] A fixed air gap is formed between the stationary end plate bump group and the moving end plate bump group. The stationary end plate bump group and the moving end plate bump group are provided with a phase difference in the circumferential direction. The moving end plate bump group generates relative motion with the stationary end plate bump group through the rotation of the motor rotor, generating a magnetoresistive modulation effect to change the magnetic circuit distribution at the motor end, thereby weakening the motor cogging torque.

[0008] As a further improvement of this utility model, the soft magnetic material moving end piece is fixed to the rotor end piece at the end of the motor rotor by laser welding, and a number of laser welding points formed by laser welding are distributed at intervals along the circumference of the rotor end piece.

[0009] As a further improvement of this utility model, the relationship between the mass m of each laser welding point and the radius r of the radial distribution position of each laser welding point in the circumferential direction of the rotor end plate is: Σm·r 2 =U, where U is the unbalance required for dynamic balance of the motor rotor.

[0010] As a further improvement of this utility model, it also includes a stationary end piece connecting bracket, which is detachably installed on the side of the motor rear end cover facing the soft magnetic material moving end piece; the stationary end piece is detachably installed on the stationary end piece connecting bracket.

[0011] As a further improvement of this utility model, the thickness of both the moving end piece and the stationary end piece of the soft magnetic material is no more than 1 mm.

[0012] As a further improvement of this utility model, the shapes of the first protrusion and the second protrusion both include rectangle, trapezoid, arc, or involute.

[0013] As a further improvement of this utility model, the height of the first protrusion and the second protrusion is no greater than 0.5mm.

[0014] As a further improvement of this utility model, the width of the fixed air gap is 0.5-0.7mm.

[0015] As a further improvement of this utility model, the phase difference between the stationary end plate bump group and the moving end plate bump group is: Δθ=360 / LCM(P,QS); where LCM is the least common multiple, P is the number of motor poles, and QS is the number of motor slots.

[0016] As a further improvement of this utility model, the stationary end piece is a stationary end piece made of soft magnetic material.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0018] This invention utilizes a structure design that incorporates a moving end piece and a stationary end piece made of soft magnetic material. The moving end piece provides a low magnetic resistance channel for leakage magnetic flux at the rotor end of the motor, while the stationary end piece works in conjunction with it to form a low magnetic resistance path. This design guides the leakage magnetic flux that would normally flow to the end bearing to the low magnetic resistance path, significantly reducing the magnetic field strength at the bearing. This effectively avoids the problem of reduced motor reliability caused by the easy magnetization of the end bearing, and eliminates the need for complex or costly methods such as existing magnetic shielding covers or ceramic bearings.

[0019] This invention utilizes the circumferential phase difference design between the convex groups of the moving end plate and the convex groups of the stationary end plate, as well as the magnetoresistive modulation effect formed by the relative motion between the moving end plate and the convex groups of the stationary end plate as the motor rotor rotates, to change the magnetic circuit distribution at the motor end and weaken the inherent cogging torque of the motor. At the same time, it combines the dynamic balance counterweight function of the weld point when the moving end plate is fixed by laser welding to compensate for the rotor imbalance. This collaboratively solves the problem that the superimposed cogging torque of the rotor dynamic balance can easily cause vibration and noise, and avoids the shortcomings of existing methods such as improving processing accuracy, skewed poles, adding magnetic rings, or active control, which are limited by process limitations, complex structures, or high costs.

[0020] This utility model simplifies the overall structural design, adopts mature laser welding technology without the need for secondary clamping, and improves assembly flexibility through a detachable stationary end piece connecting bracket. It solves the defects of existing solutions, such as complex structure, high cost, or limited process, and adapts to the compact design requirements of permanent magnet synchronous motors in modern electric power steering systems, taking into account both practicality and economy. Attached Figure Description

[0021] Figure 1 This is a side sectional view of the end face reluctance compensator of the permanent magnet synchronous motor pole slot assembly in an automotive steering system disclosed in an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the end face magnetoresistive compensator of the permanent magnet synchronous motor pole slot combination in an automotive steering system disclosed in one embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the installation of the end face magnetoresistive compensator of the permanent magnet synchronous motor pole slot combination in an automotive steering system, as disclosed in one embodiment of this utility model.

[0024] Figure 4 This is a schematic diagram of the end face magnetoresistive compensator of the permanent magnet synchronous motor pole slot combination in an automotive steering system disclosed in one embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the installation of the end face magnetoresistive compensator of the permanent magnet synchronous motor pole slot combination in an automotive steering system, as disclosed in one embodiment of this utility model.

[0026] In the picture:

[0027] 1. Soft magnetic material moving end piece; 1-1. First protrusion; 2. Stationary end piece; 2-1. Second protrusion; 3. Motor rotor; 3-1. Rotor end piece; 4. Motor rear end cover; 5. Laser weld point; 6. Stationary end piece connecting bracket; 7. Mounting bolt; 8. Mounting nut. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0029] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] The present invention will now be described in further detail with reference to the accompanying drawings:

[0032] like Figure 1As shown, the end face magnetic reluctance compensator for the pole slot combination of a permanent magnet synchronous motor in an automotive steering system according to this utility model includes: a soft magnetic material moving end piece 1 and a stationary end piece 2. The soft magnetic material moving end piece 1 provides a low magnetic reluctance channel for leakage magnetic flux at the end of the motor rotor 3. It is welded and fixed to the end of the motor rotor 3, and a plurality of first protrusions 1-1 are evenly spaced along its outer circumference, forming a protrusion group for the moving end piece. The stationary end piece 2 cooperates with the soft magnetic material moving end piece 1 to form a low magnetic reluctance channel for leakage magnetic flux at the end of the motor rotor 3. The passage is fixed on the side of the motor rear end cover 4 facing the soft magnetic material moving end piece 1. Several second protrusions 2-1 are evenly spaced along the circumferential direction on its outer periphery. Several second protrusions 2-1 constitute the stationary end piece protrusion group. A fixed air gap is formed between the stationary end piece protrusion group and the moving end piece protrusion group. The stationary end piece protrusion group and the moving end piece protrusion group are provided with a phase difference in the circumferential direction. The moving end piece protrusion group generates relative motion with the stationary end piece protrusion group through the rotation of the motor rotor 3, generating a magnetic reluctance modulation effect to change the magnetic circuit distribution at the motor end, thereby weakening the motor cogging torque.

[0033] Specifically:

[0034] like Figure 2-3 As shown, in the above embodiment, preferably, the soft magnetic material moving end piece 1 is fixed to the rotor end piece 3-1 at the end of the motor rotor 3 by laser welding, and a plurality of laser welding points 5 formed by laser welding are distributed circumferentially along the rotor end piece 3-1. The soft magnetic material moving end piece 1 provides a low magnetic resistance channel for the leakage magnetic flux at the rotor end, reduces the leakage amount, reduces the magnetization effect on the end bearing, enhances the main magnetic circuit, and improves the motor's power performance.

[0035] In the above embodiment, preferably, the relationship between the mass m of each laser welding point 5 and the radius r of the radial distribution position of each laser welding point 5 in the circumferential direction of the rotor end plate 3-1 is: Σm·r 2 =U, where U is the unbalance required for the dynamic balance of the motor rotor 3. In this embodiment, each laser welding point 5 not only serves as a means of fixing the soft magnetic material moving end piece 1 to the rotor end piece 3-1, but also acts as a balancing counterweight. By adjusting the mass m of each laser welding point 5 and the radial position r of each laser welding point 5 in the circumferential direction of the rotor end piece 3-1 according to the above relationship, the inertia of the system rotation can be finely adjusted; that is, in this embodiment, the soft magnetic material moving end piece 1 is fixed to the rotor end piece 3-1 by laser welding, and the position and mass of each laser welding point 5 are adjustable for the purpose of fine-tuning the dynamic balance of the rotor.

[0036] like Figure 4-5As shown, in the above embodiment, preferably, it also includes a stationary end piece connecting bracket 6, mounting bolts 7, and mounting nuts 8. The stationary end piece connecting bracket 6 is placed on the side of the motor rear end cover 4 facing the soft magnetic material moving end piece 1, and the stationary end piece 2 is placed on the side of the stationary end piece connecting bracket 6 close to the soft magnetic material moving end piece 1. In this embodiment, the stationary end piece connecting bracket 6 is indirectly fixed to the motor rear end cover 4 by the mounting bolts 7, and the stationary end piece 2 is mounted on the stationary end piece connecting bracket 6 by the mounting nuts 8.

[0037] In the above embodiments, preferably, both the moving end piece 1 and the stationary end piece 2 of the soft magnetic material can be completed by blanking and stamping in one step, eliminating the need for machining or secondary assembly and reducing production costs.

[0038] In the above embodiments, preferably, the thickness of both the moving end piece 1 and the stationary end piece 2 of the soft magnetic material is no greater than 1 mm.

[0039] In the above embodiments, preferably, the shapes of the first protrusion 1-1 and the second protrusion 2-1 both include rectangles, trapezoids, arcs, or involutes to meet the requirements for noise, strength, and process differentiation. The heights of the first protrusion 1-1 and the second protrusion 2-1 are both no greater than 0.5mm.

[0040] In the above embodiments, preferably, the width of the fixed air gap is 0.5-0.7 mm.

[0041] In the above embodiments, preferably, the number of the first convex point 1-1 and the second convex point 2-1 is initially obtained based on the number of motor poles p, the number of motor slots Qs, and the target weakening order k, and is locked based on the basic magnetic slot torque characteristics of the motor. In this embodiment, taking an 8-pole 12-slot motor as an example, the physical characteristics determine that with 8 poles and 12 slots, the magnetic slot torque fluctuation of the motor is mainly distributed at the 8th and 12th orders. If the 12th order of the motor's magnetic slot torque accounts for the highest proportion, then 12 convex points are used.

[0042] In the above embodiments, preferably, the phase difference between the stationary end plate bump group and the moving end plate bump group is: Δθ = 360 / LCM(P, QS); where LCM is the least common multiple, P is the number of motor poles, and QS is the number of motor slots. In this embodiment, taking an 8-pole 12-slot motor as an example, the least common multiple of the number of poles 8 and the number of slots 12 is 24, and the phase difference Δθ = 360 / 24 = 15°.

[0043] In the above embodiments, preferably, the stationary end piece 2 is a stationary end piece made of soft magnetic material.

[0044] The advantages of this utility model are:

[0045] This invention utilizes a structure design that sets up a soft magnetic material moving end piece 1 and a stationary end piece 2. The soft magnetic material moving end piece 1 provides a low magnetic resistance channel for the leakage magnetic flux at the end of the motor rotor 3, and the stationary end piece 2 cooperates with it to form a low magnetic resistance path. This design guides the leakage magnetic flux that originally flowed to the end bearing to the low magnetic resistance path, significantly reducing the magnetic field strength at the bearing. This effectively avoids the problem of reduced motor reliability caused by the easy magnetization of the end bearing, and eliminates the need for complex or costly methods such as existing magnetic shielding covers and ceramic bearings.

[0046] This invention utilizes the circumferential phase difference design between the moving end plate convex group and the stationary end plate convex group, as well as the magnetoresistive modulation effect formed by the relative motion between the soft magnetic material moving end plate 1 and the stationary end plate convex group as the motor rotor rotates, to change the magnetic circuit distribution at the motor end and weaken the inherent cogging torque of the motor. At the same time, it combines the dynamic balance counterweight function of the weld point when the soft magnetic material moving end plate 1 is fixed by laser welding to compensate for the rotor imbalance. This collaboratively solves the problem that the superimposed cogging torque of the rotor dynamic balance can easily cause vibration and noise, and avoids the shortcomings of existing methods such as improving processing accuracy, skewed poles, adding magnetic rings, or active control, which are limited by process limitations, complex structures, or high costs.

[0047] This utility model simplifies the overall structural design, adopts mature laser welding technology without the need for secondary clamping, and improves assembly flexibility through a detachable stationary end piece connecting bracket. It solves the defects of existing solutions, such as complex structure, high cost, or limited process, and adapts to the compact design requirements of permanent magnet synchronous motors in modern electric power steering systems, taking into account both practicality and economy.

[0048] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An end-face reluctance compensator for a permanent magnet synchronous motor pole-slot combination in an automotive steering system, characterized in that, include: The soft magnetic material moving end piece (1) is used to provide a low magnetic resistance channel for leakage magnetic flux at the end of the motor rotor (3). It is welded and fixed to the end of the motor rotor (3). Several first protrusions (1-1) are evenly spaced along the circumferential direction on its outer periphery. Several first protrusions (1-1) constitute the moving end piece protrusion group. The stationary end piece (2) cooperates with the soft magnetic material moving end piece (1) to form a low magnetic resistance path for leakage magnetic flux at the end of the motor rotor (3); It is fixed on the side of the motor rear end cover (4) facing the soft magnetic material moving end piece (1), and a number of second protrusions (2-1) are evenly spaced along the circumferential direction on its outer periphery. The number of second protrusions (2-1) constitutes the stationary end piece protrusion group. A fixed air gap is formed between the stationary end plate protrusion group and the moving end plate protrusion group. The stationary end plate protrusion group and the moving end plate protrusion group are provided with a phase difference in the circumferential direction. The moving end plate protrusion group generates relative motion with the stationary end plate protrusion group through the rotation of the motor rotor (3), generating a magnetic reluctance modulation effect to change the magnetic circuit distribution at the motor end, thereby weakening the motor cogging torque.

2. The end-face magnetoresistive compensator according to claim 1, characterized in that, The soft magnetic material moving end piece (1) is fixed to the rotor end piece (3-1) at the end of the motor rotor (3) by laser welding, and a number of laser welding points (5) formed by laser welding are distributed circumferentially along the rotor end piece (3-1).

3. The end-face magnetoresistive compensator according to claim 2, characterized in that, The relationship between the mass m of each laser welding point (5) and the radius r of the radial distribution position of each laser welding point (5) in the circumferential direction of the rotor end plate (3-1) is: Σm·r 2 =U, where U is the unbalanced amount required for dynamic balance of the motor rotor (3).

4. The end-face magnetoresistive compensator according to claim 1, characterized in that, It also includes a stationary end piece connecting bracket (6), which is detachably mounted on the side of the motor rear end cover (4) facing the soft magnetic material moving end piece (1); the stationary end piece (2) is detachably mounted on the stationary end piece connecting bracket (6).

5. The end-face magnetoresistive compensator according to claim 1, characterized in that, The thickness of both the moving end piece (1) and the stationary end piece (2) of the soft magnetic material is no greater than 1 mm.

6. The end-face magnetoresistive compensator according to claim 1, characterized in that, The shapes of the first protrusion (1-1) and the second protrusion (2-1) include rectangle, trapezoid, arc or involute.

7. The end-face magnetoresistive compensator according to claim 1, characterized in that, The height of the first protrusion (1-1) and the second protrusion (2-1) is no greater than 0.5mm.

8. The end-face magnetoresistive compensator according to claim 1, characterized in that, The width of the fixed air gap is 0.5-0.7 mm.

9. The end-face magnetoresistive compensator according to claim 1, characterized in that, The phase difference between the stationary end plate bump group and the moving end plate bump group is: Δθ = 360 / LCM(P, QS); where LCM is the least common multiple, P is the number of motor poles, and QS is the number of motor slots.

10. The end-face magnetoresistive compensator according to claim 1, characterized in that, The stationary end piece (2) is a stationary end piece made of soft magnetic material.

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