Electric motor, electric power steering system and vehicle

Abstract

This invention provides an electric motor, an electric power steering system, and a vehicle. The motor includes a stator core, a rotor core, and an air gap. The rotor core is located inside the stator core, and the air gap is located between the rotor core and the stator core. The axial height Ls of the stator core, the outer diameter Dso of the stator core, the stator split ratio k of the stator core, the axial height Lr of the rotor core, and the width lg of the air gap satisfy the following: This application optimizes the dimensional relationship between the stator core, the rotor core, and the air gap between them. Without increasing the number of components, it effectively solves the problem of motor performance degradation caused by end magnetic leakage, thereby reducing cogging torque, suppressing torque pulsation, increasing the average torque of the motor, and improving motor vibration and noise. While ensuring motor performance, it can minimize motor weight and reduce production costs.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically, to a motor, an electric power steering system, and a vehicle. Background Technology

[0002] Currently, motors inevitably suffer from end magnetic leakage, which severely affects the motor's output torque and torque pulsation, and worsens the motor's mechanical vibration and noise.

[0003] However, taking measures to suppress the impact of end leakage flux on motor performance introduces new problems such as increased motor weight and cost. Therefore, how to effectively suppress end leakage flux while ensuring motor performance without increasing motor weight and production costs has become a pressing issue. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] Therefore, the first aspect of the present invention is to provide an electric motor.

[0006] A second aspect of the invention is to provide an electric power steering system.

[0007] A third aspect of the invention is that a vehicle is provided.

[0008] In view of this, according to a first aspect of the present invention, an electric motor is provided, comprising a stator core, a rotor core, and an air gap, wherein the rotor core is disposed inside the stator core, and the air gap is located between the rotor core and the stator core. The axial height Ls of the stator core, the outer diameter Dso of the stator core, the stator split ratio k of the stator core, the axial height Lr of the rotor core, and the width lg of the air gap satisfy the following:

[0009] The motor provided by this invention includes a stator core, a rotor core, and an air gap. An air gap exists between the rotor core and the stator core, allowing the rotor core to rotate relative to the stator core. The axial height of the stator core is Ls, the axial height of the rotor core is Lr, the absolute value of the difference between the axial heights of the stator and rotor cores is |Ls-Lr|, the outer diameter of the stator core is Dso, the stator split ratio is k (the ratio of the inner diameter to the outer diameter of the stator core), and the width of the air gap is lg, satisfying the above relationship. This application optimizes the dimensional relationships of the stator core, rotor core, and the air gap between them. Without increasing the number of components, it effectively solves the problem of motor performance degradation caused by end magnetic leakage, thereby reducing cogging torque, suppressing torque pulsation, increasing the average torque of the motor, and improving motor vibration and noise. While ensuring motor performance, it also minimizes motor weight and reduces production costs.

[0010] Furthermore, Let X be the value of the difference in axial height between the stator core and the rotor core, |Ls-Lr|, be denoted as ΔL. Using the equality of the axial heights Ls and Lr of the stator core (i.e., Ls = Lr, ΔL = X = 0) as a benchmark, we study the changes in motor performance and cost under different ΔL values. Tave* and Cost* are per-unit values. Tave* is the ratio of the torque value under different X values ​​to the average torque when X = 0, and Cost* is the ratio of the motor cost under different X values ​​to the motor cost when X = 0. When 0 ≤ X ≤ 0.4, Tave* is at a relatively optimal level, and Cost* remains at a low level, thus ensuring average torque output, preventing the motor performance from being affected by end leakage flux, and controlling motor production costs.

[0011] It's important to note that cogging torque refers to the torque generated when the armature winding is open, caused by the interaction between the magnetic field of the permanent magnet and the armature cogging teeth. Cogging torque is the tangential component of the force between the permanent magnet's magnetic field and the cogging teeth. Cogging torque always attempts to position the rotor at a specific location, hence it's also called cogging positioning torque. Cogging torque causes torque and speed fluctuations in the motor, resulting in vibration and noise. When the frequency of the torque pulsation coincides with the armature current resonant frequency, resonance occurs, amplifying the vibration and noise of the cogging torque and severely affecting the motor's positioning accuracy and servo performance, especially at low speeds. Furthermore, when the torque pulsation is too large, the stability of the energy driven by the mechanical load decreases, thus impacting the motor's performance.

[0012] For permanent magnet motors, torque pulsation mainly includes ripple torque fluctuation and reluctance torque fluctuation. Ripple torque refers to the torque fluctuation caused by higher harmonics in the back EMF and armature current. Reluctance torque fluctuation refers to the torque fluctuation caused by the uneven rotor reluctance, which leads to unequal inductance between the direct axis and quadrature axis of the motor.

[0013] Per-unit values ​​are a type of relative unit system. They are a commonly used numerical notation method in power system analysis and engineering calculations, representing the relative values ​​of various physical quantities and parameters, with the unit being pu (which can also be considered dimensionless). Per-unit values ​​are also widely used in power system calculations.

[0014] In one possible design, further, the axial height Ls of the stator core, the outer diameter Dso of the stator core, the stator split ratio k of the stator core, the axial height Lr of the rotor core, and the width lg of the air gap satisfy:

[0015] In this design, when 0 ≤ X < 0.02, as X increases, Cost* increases almost linearly, and Tave* also increases. However, the increase in Tave* is less than 1%, meaning that when X is in the range [0, 0.02), parameter changes have limited effect on optimizing motor performance. As X increases, when it satisfies 0.02 ≤ X ≤ 0.12, Cost* increases almost linearly, and Tave* also increases significantly. At this point, the increase in motor cost is not obvious, but motor performance is significantly improved. When X continues to increase, satisfying 0.12 < X ≤ 0.4, Cost* increases linearly, but Tave* remains basically unchanged. In other words, within this range, motor cost increases while motor performance remains unchanged; that is, within this range, parameter changes do not contribute much to the cost-effectiveness of the motor. Therefore, choosing 0.02 ≤ X ≤ 0.12 can effectively control motor cost and improve motor performance, thus enhancing the overall cost-effectiveness of the motor.

[0016] In one possible design, the stator splitting ratio k further satisfies the condition that 0 < k ≤ 0.7.

[0017] In this design, the stator split ratio is the ratio of the inner diameter to the outer diameter of the stator core. By optimizing the stator split ratio, the torque density can be increased, thereby improving the motor performance.

[0018] In one possible design, further, the width lg of the air gap satisfies,

[0019] In this design, the air gap is located between the stator core and the rotor core. The width of the air gap needs to satisfy the above relationship to ensure that the width of the air gap is within a suitable range. The size of the air gap determines the magnitude of the magnetic flux. If the air gap is too large, the magnetic reluctance increases, the magnetic flux decreases, and leakage flux increases, resulting in a decrease in motor efficiency. If the air gap is too small, on the one hand, the small air gap affects the manufacturing process, making it difficult to assemble the rotor core and stator core; on the other hand, when the rotor core rotates relative to the stator core, friction easily occurs between the two, causing rotor rubbing and burning out the motor.

[0020] It should be noted that the stator core includes a stator yoke and multiple stator teeth. The multiple stator teeth are connected at intervals on the stator yoke. The air gap is located between the stator teeth and the rotor core. The width lg of the air gap refers to the radial distance between the rotor core and the stator teeth.

[0021] In one possible design, the central axis of the stator core further overlaps with the central axis of the rotor core.

[0022] In this design, the central axis of the rotor core coincides with the central axis of the stator core. When the rotor core rotates relative to the stator core, the rotation space required by the rotor core is a regular cylinder. The regular cylinder is either fitted inside the stator core or fitted outside the stator core. The coincidence of their central axes can minimize the required radial space, thereby effectively controlling the radial dimensions of the motor and adapting to the trend of miniaturization of the entire motor.

[0023] Specifically, when the central axis of the rotor core does not coincide with the central axis of the stator core, the rotor core is eccentrically positioned relative to the stator core, and the radial dimension occupied by both will be larger, which goes against the trend of miniaturization of motors.

[0024] In one possible design, the motor further includes a magnet slot and a first permanent magnet, the magnet slot being axially extended through the rotor core, and the first permanent magnet being disposed within the magnet slot.

[0025] In this design, the rotor core is provided with a magnet slot, which runs through the interior of the rotor core. The first permanent magnet is embedded in the magnet slot and contacts the rotor core. The magnet slot facilitates the positioning and installation of the first permanent magnet and ensures the positional stability of the first permanent magnet. When the first permanent magnet located inside the rotor core rotates synchronously with the rotor core, the slot wall can provide multi-directional positional constraints for the first permanent magnet, ensuring the positional stability of the rotor core and the first permanent magnet.

[0026] The rotor core has multiple magnet slots, which are distributed circumferentially on the rotor core. There are also multiple first permanent magnets, with one first permanent magnet embedded in one magnet slot.

[0027] In one possible design, the motor further includes a second permanent magnet disposed on the side of the rotor core facing the stator core.

[0028] In this design, the rotor core includes circumferentially oriented side surfaces. When the rotor core is located inside the stator core, the second permanent magnet is attached to the outer circumferential surface of the rotor core. When the rotor core is located outside the stator core, the second permanent magnet is attached to the inner circumferential surface of the rotor core. It is worth noting that the second permanent magnet is located between the rotor core and the stator core.

[0029] The second permanent magnet can be glued to the rotor core, or it can be fixed to the rotor core by injection molding.

[0030] In one possible design, the number of second permanent magnets is further increased to a plurality, and the plurality of second permanent magnets are evenly spaced apart.

[0031] In this design, multiple second permanent magnets are evenly spaced and surface-mounted on the side of the rotor core to improve structural symmetry and thus improve motor efficiency.

[0032] In one possible design, the rotor core further includes core segments arranged axially, with at least two core segments.

[0033] In this design, the rotor core comprises core segments, with at least two segments stacked axially. The main purpose of the segmented design of the rotor core is to obtain a skewed rotor, where adjacent core segments are offset at a certain angle in the circumferential direction. The function of the skewed rotor is to reduce the cogging torque and torque pulsation of the motor, thereby improving motor performance.

[0034] Furthermore, in the manufacturing process of the rotor core, rotor laminations can be stacked to form core segments, and then these segments can be stacked again. This divides the rotor core formation into two steps, allowing for better control of stacking accuracy, early detection of stacking deviations, and ensuring the precision of rotor core stacking. Directly stacking multiple rotor laminations to form the rotor core is much more difficult.

[0035] In one possible design, the air gap is further described as a uniform air gap.

[0036] In this design, the stator core includes a stator yoke and stator teeth. The stator teeth are connected to the stator yoke and are positioned closer to the rotor core than the stator yoke. An air gap exists between the stator teeth and the rotor core. By ensuring a uniform air gap—meaning that the distance between the stator teeth and the rotor core is equal at all locations—the motor output torque is high, the power density is high, and the efficiency is high.

[0037] In one possible design, the air gap is further described as a non-uniform air gap.

[0038] In this design, there are multiple stator teeth, and the distance between each stator tooth and the rotor core is not entirely equal at different positions. That is, the distance can gradually increase or decrease along the circumferential direction, or increase first and then decrease. When the distance between the stator teeth and the rotor core is uneven, the magnetic field waveform can be improved by properly setting the uneven air gap, reducing the cogging torque amplitude and rotor core losses. This increases the motor's output torque and improves motor performance.

[0039] In one possible design, the stator core further includes a stator yoke and multiple stator teeth, the multiple stator teeth being spaced apart and connected to the stator yoke, the multiple stator teeth enclosing to form a rotor cavity, and the rotor core being located inside the rotor cavity.

[0040] In this design, the stator core includes a stator yoke and multiple stator teeth. The stator yoke has a ring structure, and the multiple stator teeth are connected at intervals on the stator yoke. The multiple stator teeth enclose and form a rotor cavity, which is located inside the stator core. The rotor core is located inside the rotor cavity; that is, the rotor core is an inner rotor. The air gap is located between the stator teeth and the rotor core, and the width of the air gap is the radial distance between the stator teeth and the rotor core.

[0041] In one possible design, the stator core further comprises multiple core blocks joined together circumferentially.

[0042] In this design, the stator core comprises multiple core blocks, each including a sub-yoke and a stator tooth section. These core blocks are circumferentially joined together, and the sub-yokes are interconnected to form the stator yoke section, creating a ring-like structure. In other words, the stator yoke section can be a single, integral ring structure or composed of multiple joined sub-yokes. This segmented stator core facilitates the winding of the stator windings. After each core block completes its stator winding, they are then assembled to form a complete stator core. This simplifies the winding process and also improves the slot fill factor between adjacent stator teeth, allowing the stator windings to be better positioned within the slots. This improvement in stator winding assembly enhances motor performance.

[0043] According to a second aspect of the invention, an electric power steering system is provided, comprising a motor provided by any of the above-described designs.

[0044] The electric power steering system provided by the present invention includes the motor provided by any of the above designs, and therefore has all the beneficial effects of the motor, which will not be repeated here.

[0045] Electric Power Steering (EPS) is a power steering system that directly relies on an electric motor to provide auxiliary torque. Compared to the traditional Hydraulic Power Steering (HPS) system, EPS has a simpler structure, more flexible assembly, saves energy, and protects the environment. Most modern vehicles are equipped with EPS systems. EPS mainly consists of a torque sensor, vehicle speed sensor, electric motor, reduction gear, and electronic control unit (ECU).

[0046] According to a third aspect of the invention, a vehicle is provided, comprising an electric motor or electric power steering system provided by any of the above designs.

[0047] The vehicle provided by the present invention includes the electric motor or electric power steering system provided by any of the above designs, and therefore has all the beneficial effects of the electric motor or electric power steering system, which will not be repeated here.

[0048] It should be noted that the vehicles include both new energy vehicles and traditional fuel vehicles.

[0049] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0050] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0051] Figure 1 A schematic diagram of the motor structure is shown in one embodiment of the present invention;

[0052] Figure 2 A graph illustrating the performance and cost analysis of a motor according to an embodiment of the present invention is shown;

[0053] Figure 3 A schematic diagram of a motor having a uniform air gap is shown in one embodiment of the present invention;

[0054] Figure 4 A schematic diagram of a motor having a non-uniform air gap is shown in one embodiment of the present invention;

[0055] Figure 5 A schematic diagram of a motor having a second permanent magnet is shown in one embodiment of the present invention;

[0056] Figure 6 A schematic diagram of the structure of the core block according to one embodiment of the present invention is shown;

[0057] Figure 7 A schematic diagram of an electric power steering system according to an embodiment of the present invention is shown.

[0058] in, Figures 1 to 7 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0059] 100 motor,

[0060] 110 Stator core, 111 Stator yoke, 112 Stator teeth, 113 Core block

[0061] 120 rotor core, 121 core section,

[0062] 130 air gap,

[0063] 140 Magnet slot, 141 First permanent magnet, 142 Second permanent magnet.

[0064] 200 electric power steering system,

[0065] 211 Steering wheel, 212 Steering shaft, 213 Universal coupling, 214 Rotary shaft, 215 Rack and pinion mechanism, 216 Rack and pinion shaft, 217 Wheel.

[0066] 221 Steering torque sensor, 222 Control unit, 223 Reduction mechanism. Detailed Implementation

[0067] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0068] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0069] The following reference Figures 1 to 7 The invention describes an electric motor 100, an electric power steering system, and a vehicle provided according to some embodiments of the invention.

[0070] According to an embodiment of the first aspect of the present invention, such as Figure 1As shown, a motor 100 is provided, which includes a stator core 110, a rotor core 120, and an air gap 130. The rotor core 120 is disposed inside the stator core 110, and the air gap 130 is located between the rotor core 120 and the stator core 110. The axial height Ls of the stator core 110, the outer diameter Dso of the stator core 110, the stator split ratio k of the stator core 110, the axial height Lr of the rotor core 120, and the width lg of the air gap 130 satisfy the following:

[0071] The motor 100 provided by the present invention includes a stator core 110, a rotor core 120, and an air gap 130. An air gap 130 exists between the rotor core 120 and the stator core 110, and the rotor core 120 is rotatable relative to the stator core 110. The axial height of the stator core 110 is Ls, the axial height of the rotor core 120 is Lr, the absolute value of the difference between the axial heights of the stator core 110 and the rotor core 120 is |Ls-Lr|, the outer diameter of the stator core 110 is Dso, the stator split ratio of the stator core 110 is k, the stator split ratio is the ratio of the inner diameter of the stator core 110 to the outer diameter of the stator core 110, and the width of the air gap 130 is lg, satisfying the above relationship. This application optimizes the dimensional relationship between the stator core 110, the rotor core 120, and the air gap 130 between them. Without adding any components, it can effectively solve the problem of performance degradation of the motor 100 caused by end magnetic leakage. This reduces cogging torque, suppresses torque pulsation, increases the average torque of the motor 100, and improves the vibration and noise of the motor 100. While ensuring the performance of the motor 100, it can minimize the weight of the motor 100 and reduce production costs.

[0072] It should be noted that, for example Figure 2 As shown, in related technologies, end leakage flux in motors exists on both axial end faces and is unavoidable. The rotor core contains permanent magnets, and most of the total magnetic flux provided by the permanent magnets near the axial end faces will link with the winding turns on the stator core along the main magnetic path to form the main magnetic flux. A portion of the flux, due to end effects, does not link with the winding turns. This end leakage flux not only causes a decrease in motor torque but also affects the cogging torque and torque pulsation, worsening the motor's vibration and noise.

[0073] Furthermore, Let X be the axial height difference between the stator core 110 and the rotor core 120, denoted as |Ls-Lr|. Using the equality of the axial heights Ls of the stator core 110 and Lr of the rotor core 120 (i.e., Ls=Lr, ΔL=X=0) as a benchmark, we study the changes in the performance and cost of the motor 100 under different ΔL values. Figure 2As shown in the figure, Tave* and Cost* are per-unit values. Tave* is the ratio of the torque value under different values ​​of X to the average torque when X=0, and Cost* is the ratio of the cost of motor 100 under different values ​​of X to the cost of motor 100 when X=0. When 0≤X≤0.4, Tave* is at a better level, and Cost* is maintained at a lower level, thus ensuring the average torque output and ensuring that the performance of motor 100 is not affected by end leakage flux, while also controlling the production cost of motor 100.

[0074] It should be noted that cogging torque refers to the torque generated by the interaction between the magnetic field produced by the permanent magnet and the armature cogging when the armature winding is open-circuited. Cogging torque is the tangential component of the force between the permanent magnet magnetic field and the cogging. Cogging torque always attempts to position the rotor at a certain location, and is also called cogging positioning torque. Cogging torque causes torque and speed fluctuations in motor 100, resulting in vibration and noise. When the frequency of torque pulsation coincides with the resonant frequency of the armature current, resonance will occur, which will inevitably amplify the vibration and noise of cogging torque, seriously affecting the positioning accuracy and servo performance of motor 100, especially at low speeds. In particular, when the torque pulsation is too large, the stability of the mechanical load energy driven by motor 100 will decrease, thus affecting the performance of motor 100.

[0075] For permanent magnet motors, torque pulsation mainly includes ripple torque fluctuation and reluctance torque fluctuation. Ripple torque refers to the torque fluctuation caused by higher harmonics in the back EMF and armature current. Reluctance torque fluctuation refers to the torque fluctuation caused by the uneven rotor reluctance, which leads to unequal inductance between the direct axis and quadrature axis of the motor.

[0076] Per-unit values ​​are a type of relative unit system. They are a commonly used numerical notation method in power system analysis and engineering calculations, representing the relative values ​​of various physical quantities and parameters, with the unit being pu (which can also be considered dimensionless). Per-unit values ​​are also widely used in power system calculations.

[0077] Furthermore, such as Figure 1 and Figure 2 As shown, the axial height Ls of the stator core 110, the outer diameter Dso of the stator core 110, the stator split ratio k of the stator core 110, the axial height Lr of the rotor core 120, and the width lg of the air gap 130 satisfy the following:

[0078] In this embodiment, such as Figure 2As shown, when 0 ≤ X < 0.02, Cost* increases linearly with increasing X, and Tave* also increases. However, the increase in Tave* is less than 1%, meaning that when X is in the range [0, 0.02), the parameter change has limited effect on optimizing the performance of motor 100. With increasing X, when 0.02 ≤ X ≤ 0.12, Cost* increases linearly, and Tave* also increases significantly. At this point, the cost of motor 100 does not increase significantly, but its performance improves noticeably. When X continues to increase, satisfying 0.12 < X ≤ 0.4, Cost* increases linearly, but Tave* remains essentially unchanged. This means that within this range, the cost of motor 100 increases while its performance remains unchanged; therefore, within this range, the parameter change has little contribution to the cost-effectiveness of motor 100. Therefore, choosing 0.02≤X≤0.12 can not only effectively control the cost of motor 100, but also effectively improve the performance of motor 100 and enhance the overall cost-effectiveness of motor 100.

[0079] Furthermore, the range of values ​​for the stator splitting ratio k satisfies 0 < k ≤ 0.7.

[0080] In this embodiment, the stator split ratio is the ratio of the inner diameter to the outer diameter of the stator core 110. By optimizing the stator split ratio, the torque density can be increased, thereby improving the performance of the motor 100.

[0081] Furthermore, the width lg of the air gap 130 satisfies,

[0082] In this embodiment, the air gap 130 is located between the stator core 110 and the rotor core 120. The width of the air gap 130 needs to satisfy the above-mentioned relationship to ensure that the width of the air gap 130 is within a suitable range. The size of the air gap 130 determines the magnitude of the magnetic flux. If the air gap 130 is too large, the magnetic reluctance will increase, the magnetic flux will decrease, and the leakage flux will increase, resulting in a decrease in the efficiency of the motor 100. If the air gap 130 is too small, on the one hand, the small air gap 130 will affect the manufacturing process, making it difficult to assemble the rotor core 120 and the stator core 110; on the other hand, when the rotor core 120 rotates relative to the stator core 110, friction is likely to occur between the two, causing rotor rubbing and burning out the motor 100.

[0083] It should be noted that the stator core 110 includes a stator yoke 111 and a plurality of stator teeth 112, which are spaced apart on the stator yoke 111. The air gap 130 is located between the stator teeth 112 and the rotor core 120. The width lg of the air gap 130 refers to the radial distance between the rotor core 120 and the stator teeth 112.

[0084] Furthermore, such as Figure 1As shown, the central axis of the stator core 110 overlaps with the central axis of the rotor core 120.

[0085] In this embodiment, the central axis of the rotor core 120 coincides with the central axis of the stator core 110. When the rotor core 120 rotates relative to the stator core 110, the rotation space required by the rotor core 120 is a regular cylinder. The regular cylinder is either fitted inside the stator core 110 or fitted outside the stator core 110. The coincidence of their central axes can minimize the required radial space, thereby effectively controlling the radial dimension of the motor 100 and adapting to the trend of miniaturization of the entire motor 100.

[0086] Specifically, when the central axis of the rotor core 120 does not coincide with the central axis of the stator core 110, the rotor core 120 is eccentrically set relative to the stator core 110, and the radial dimension occupied by both will be larger, which goes against the trend of miniaturization of the motor 100.

[0087] Furthermore, such as Figure 1 , Figure 3 and Figure 4 As shown, the motor 100 also includes a magnet slot 140 and a first permanent magnet 141. The magnet slot 140 is axially extended through the rotor core 120, and the first permanent magnet 141 is disposed in the magnet slot 140.

[0088] In this embodiment, a magnet slot 140 is provided on the rotor core 120. The magnet slot 140 is opened through the interior of the rotor core 120. The first permanent magnet 141 is embedded in the magnet slot 140 and contacts the rotor core 120. The magnet slot 140 facilitates the positioning and installation of the first permanent magnet 141 and ensures the positional stability of the first permanent magnet 141. When the first permanent magnet 141 located inside the rotor core 120 rotates synchronously with the rotor core 120, the slot wall of the magnet slot 140 can provide multi-directional positional constraints for the first permanent magnet 141, ensuring the positional stability of the rotor core 120 and the first permanent magnet 141.

[0089] The number of magnet slots 140 is multiple, and the multiple magnet slots 140 are distributed circumferentially on the rotor core 120. The number of first permanent magnets 141 is multiple, and one first permanent magnet 141 is embedded in one magnet slot 140.

[0090] Furthermore, such as Figure 5 As shown, the motor 100 also includes a second permanent magnet 142, which is disposed on the side of the rotor core 120 facing the stator core 110.

[0091] In this embodiment, the rotor core 120 includes a circumferential side surface. When the rotor core 120 is located inside the stator core 110, the second permanent magnet 142 is attached to the outer circumferential surface of the rotor core 120. When the rotor core 120 is located outside the stator core 110, the second permanent magnet 142 is attached to the inner circumferential surface of the rotor core 120. It is worth noting that the second permanent magnet 142 is located between the rotor core 120 and the stator core 110.

[0092] The second permanent magnet 142 can be glued to the rotor core 120, or the second permanent magnet 142 can be fixed to the rotor core 120 by injection molding.

[0093] Furthermore, such as Figure 5 As shown, there are multiple second permanent magnets 142, which are evenly spaced apart.

[0094] In this embodiment, multiple second permanent magnets 142 are evenly spaced and surface-mounted on the side of the rotor core 120 to improve structural symmetry and thus improve the efficiency of the motor 100.

[0095] Furthermore, such as Figure 1 As shown, the rotor core 120 includes core segments 121 arranged along the axial direction, and the number of core segments 121 is at least two.

[0096] In this embodiment, the rotor core 120 includes core segments 121, and the number of core segments 121 is at least two, which are stacked axially. The main purpose of the segmented design of the rotor core 120 is to obtain a skewed rotor, that is, two adjacent core segments 121 are offset by a certain angle in the circumferential direction. The function of the skewed rotor is to reduce the cogging torque and torque pulsation of the motor 100, thereby improving the performance of the motor 100.

[0097] Furthermore, in the manufacturing process of the rotor core 120, rotor laminations can be stacked to form core segments 121, and then the core segments 121 can be stacked. This divides the formation of the rotor core 120 into two steps, which can effectively control the stacking accuracy, detect stacking deviations early, and ensure the stacking precision of the rotor core 120. Directly stacking multiple rotor laminations to form the rotor core 120 is much more difficult.

[0098] Furthermore, such as Figure 3 and Figure 5 As shown, air gap 130 is a uniform air gap.

[0099] In this embodiment, the stator core 110 includes a stator yoke 111 and a stator tooth 112. The stator tooth 112 is connected to the stator yoke 111 and is positioned close to the rotor core 120 relative to the stator yoke 111. An air gap 130 exists between the stator tooth 112 and the rotor core 120. The air gap 130 is made uniform, meaning the distance between each position of the stator tooth 112 and the rotor core 120 is equal. In this case, the motor 100 outputs a large torque, high power density, and high efficiency.

[0100] Furthermore, such as Figure 4 As shown, air gap 130 is a non-uniform air gap.

[0101] In this embodiment, there are multiple stator teeth 112, and the distance between each stator tooth 112 and the rotor core 120 at different positions is not completely equal. That is, along the circumferential direction, the distance can gradually increase or decrease, or increase first and then decrease, etc. When the distance between the stator teeth 112 and the rotor core 120 is uneven, the magnetic field waveform can be improved by reasonably setting the uneven air gap, the cogging torque amplitude can be reduced, and the rotor core 120 loss can also be reduced, thereby increasing the output torque of the motor 100 and improving the performance of the motor 100.

[0102] Furthermore, such as Figure 1 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the stator core 110 includes a stator yoke 111 and a plurality of stator teeth 112. The plurality of stator teeth 112 are spaced apart and connected to the stator yoke 111. The plurality of stator teeth 112 enclose and form a rotor cavity, and the rotor core 120 is located inside the rotor cavity.

[0103] In this embodiment, the stator core 110 includes a stator yoke 111 and a plurality of stator teeth 112. The stator yoke 111 has a ring structure, and the plurality of stator teeth 112 are spaced apart and connected to the stator yoke 111. The plurality of stator teeth 112 enclose and form a rotor cavity, which is located inside the stator core 110. The rotor core 120 is located inside the rotor cavity, that is, the rotor core 120 is an inner rotor.

[0104] Furthermore, such as Figure 6 As shown, the stator core 110 includes multiple core blocks 113, which are spliced ​​together circumferentially.

[0105] In this embodiment, the stator core 110 includes multiple core blocks 113. Each core block 113 includes a sub-yoke and a stator tooth portion 112. The multiple core blocks 113 are spliced ​​together circumferentially, and the multiple sub-yokes are spliced ​​and connected to each other to form a stator yoke portion 111, which is a ring structure. That is, the stator yoke portion 111 can be a whole ring structure or it can be composed of multiple sub-yokes spliced ​​together. The segmented stator core 110 facilitates the winding of the stator winding. After each core block 113 completes the winding of the stator winding, they are spliced ​​and assembled to form a complete stator core 110, which facilitates the winding of the stator winding. At the same time, it can also improve the slot fill factor of the stator slots between two adjacent stator teeth, so that the stator winding is better positioned in the stator slot. This improvement in stator winding assembly enhances the performance of the motor 100.

[0106] According to an embodiment of a second aspect of the present invention, an electric power steering system 200 is provided, including a motor 100 provided in any of the above designs.

[0107] The electric power steering system 200 provided by this invention, such as Figure 7 As shown, the electric power steering system 200 includes the motor 100 provided by any of the above designs, and therefore has all the beneficial effects of the motor 100, which will not be described in detail here.

[0108] Among them, the Electric Power Steering (EPS) system is a power steering system that directly relies on the motor 100 to provide auxiliary torque. Compared with the traditional hydraulic power steering (HPS) system, the EPS system has a simpler structure and more flexible assembly. It can save energy and protect the environment. Most modern vehicles are equipped with EPS systems.

[0109] Specifically, the EPS system of this embodiment includes a steering system and an auxiliary torque mechanism that generates auxiliary torque. The EPS system generates auxiliary torque, which assists the steering torque of the steering system generated by the driver operating the steering wheel. This auxiliary torque reduces the driver's workload.

[0110] The steering system specifically includes a steering wheel 211, a steering shaft 212, a universal coupling 213, a rotating shaft 214, a rack and pinion mechanism 215, a rack and pinion shaft 216, and left and right steering wheels 217, etc.

[0111] The auxiliary torque mechanism specifically includes a steering torque sensor 221, an automotive electronic control unit (ECU) 222, a motor 100, and a reduction gear 223. Specifically, the steering torque sensor 221 detects the steering torque of the steering system. The control unit 222 generates a drive signal based on the detection signal from the steering torque sensor 221. The motor 100 generates an auxiliary torque corresponding to the steering torque based on the drive signal. The motor 100 transmits the generated auxiliary torque to the steering system via the reduction gear 223.

[0112] The motor 100 provided by this invention includes a stator core 110, a rotor core 120, and an air gap 130. The rotor core 120 and the stator core 110 have an air gap 130, and the rotor core 120 is rotatable relative to the stator core 110. The axial height of the stator core 110 is Ls, the axial height of the rotor core 120 is Lr, the absolute value of the difference between the axial heights of the stator core 110 and the rotor core 120 is |Ls-Lr|, the outer diameter of the stator core 110 is Dso, the stator split ratio of the stator core 110 is k, the stator split ratio is the ratio of the inner diameter to the outer diameter of the stator core 110, and the width of the air gap 130 is lg, satisfying the above relationship. This application optimizes the dimensional relationship between the stator core 110, the rotor core 120, and the air gap 130 between them. Without adding any components, it can effectively solve the problem of performance degradation of the motor 100 caused by end magnetic leakage. This reduces cogging torque, suppresses torque pulsation, increases the average torque of the motor 100, and improves the vibration and noise of the motor 100. While ensuring the performance of the motor 100, it can minimize the weight of the motor 100 and reduce production costs.

[0113] It should be noted that, for example Figure 2 As shown, in related technologies, end leakage flux of the motor 100 exists on both axial end faces of the motor 100 and is unavoidable. The rotor core 120 contains permanent magnets, and most of the total magnetic flux provided by the permanent magnets near the axial end faces will form the main magnetic flux along the main magnetic path with the winding turns on the stator core 110. A portion of the magnetic flux does not form the main magnetic flux with the winding turns due to end effects. This portion of end leakage flux will not only cause a decrease in the torque of the motor 100, but also affect the cogging torque and torque pulsation of the motor 100, and worsen the vibration and noise of the motor 100.

[0114] Furthermore, Let X be the axial height difference between the stator core 110 and the rotor core 120, denoted as |Ls-Lr|. Using the equality of the axial heights Ls of the stator core 110 and Lr of the rotor core 120 (i.e., Ls=Lr, ΔL=X=0) as a benchmark, we study the changes in the performance and cost of the motor 100 under different ΔL values. Figure 2 As shown in the figure, Tave* and Cost* are per-unit values. Tave* is the ratio of the torque value under different values ​​of X to the average torque when X=0, and Cost* is the ratio of the cost of motor 100 under different values ​​of X to the cost of motor 100 when X=0. When 0≤X≤0.4, Tave* is at a better level, and Cost* is maintained at a lower level, thus ensuring the average torque output and ensuring that the performance of motor 100 is not affected by end leakage flux, while also controlling the production cost of motor 100.

[0115] According to an embodiment of a third aspect of the present invention, a vehicle is provided, including a motor 100 or an electric power steering system 200 provided by any of the above designs.

[0116] The vehicle provided by the present invention includes the motor 100 or electric power steering system provided by any of the above designs, and therefore has all the beneficial effects of the motor 100 or electric power steering system 200, which will not be repeated here.

[0117] It should be noted that the vehicles can be either traditional gasoline-powered vehicles or new energy vehicles. New energy vehicles include pure electric vehicles, range-extended electric vehicles, hybrid electric vehicles, fuel cell electric vehicles, and hydrogen engine vehicles.

[0118] The motor 100 provided by this invention includes a stator core 110, a rotor core 120, and an air gap 130. The rotor core 120 and the stator core 110 have an air gap 130, and the rotor core 120 is rotatable relative to the stator core 110. The axial height of the stator core 110 is Ls, the axial height of the rotor core 120 is Lr, the absolute value of the difference between the axial heights of the stator core 110 and the rotor core 120 is |Ls-Lr|, the outer diameter of the stator core 110 is Dso, the stator split ratio of the stator core 110 is k, the stator split ratio is the ratio of the inner diameter to the outer diameter of the stator core 110, and the width of the air gap 130 is lg, satisfying the above relationship. This application optimizes the dimensional relationship between the stator core 110, the rotor core 120, and the air gap 130 between them. Without adding any components, it can effectively solve the problem of performance degradation of the motor 100 caused by end magnetic leakage. This reduces cogging torque, suppresses torque pulsation, increases the average torque of the motor 100, and improves the vibration and noise of the motor 100. While ensuring the performance of the motor 100, it can minimize the weight of the motor 100 and reduce production costs.

[0119] It should be noted that, for example Figure 2As shown, in related technologies, end leakage flux of the motor 100 exists on both axial end faces of the motor 100 and is unavoidable. The rotor core 120 contains permanent magnets, and most of the total magnetic flux provided by the permanent magnets near the axial end faces will form the main magnetic flux along the main magnetic path with the winding turns on the stator core 110. A portion of the magnetic flux does not form the main magnetic flux with the winding turns due to end effects. This portion of end leakage flux will not only cause a decrease in the torque of the motor 100, but also affect the cogging torque and torque pulsation of the motor 100, and worsen the vibration and noise of the motor 100.

[0120] Furthermore, Let X be the axial height difference between the stator core 110 and the rotor core 120, denoted as |Ls-Lr|. Using the equality of the axial heights Ls of the stator core 110 and Lr of the rotor core 120 (i.e., Ls=Lr, ΔL=X=0) as a benchmark, we study the changes in the performance and cost of the motor 100 under different ΔL values. Figure 2 As shown in the figure, Tave* and Cost* are per-unit values. Tave* is the ratio of the torque value under different values ​​of X to the average torque when X=0, and Cost* is the ratio of the cost of motor 100 under different values ​​of X to the cost of motor 100 when X=0. When 0≤X≤0.4, Tave* is at a better level, and Cost* is maintained at a lower level, thus ensuring the average torque output and ensuring that the performance of motor 100 is not affected by end leakage flux, while also controlling the production cost of motor 100.

[0121] In this invention, the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0122] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0123] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An electric motor, characterized in that, include: Stator core; Rotor core, wherein the rotor core is disposed inside the stator core; An air gap is located between the rotor core and the stator core. Wherein, the axial height Ls of the stator core, the outer diameter Dso of the stator core, the stator split ratio k of the stator core, the axial height Lr of the rotor core, and the width lg of the air gap satisfy the following: ； The stator breakage ratio is the ratio of the inner diameter of the stator core to the outer diameter of the stator core, and the range of the stator breakage ratio k is 0 < k ≤ 0.

7. The width lg of the air gap satisfies the following condition: .

2. The motor according to claim 1, characterized in that, The central axis of the stator core overlaps with the central axis of the rotor core.

3. The motor according to claim 1, characterized in that, The motor also includes: A magnet slot is axially extended through the rotor core. The first permanent magnet is disposed in the magnet slot.

4. The motor according to claim 1, characterized in that, The motor also includes: The second permanent magnet is disposed on the side of the rotor core facing the stator core.

5. The motor according to claim 4, characterized in that, The number of the second permanent magnets is multiple, and the multiple second permanent magnets are evenly spaced.

6. The motor according to claim 1, characterized in that, The rotor core includes core segments arranged along the axial direction, and the number of core segments is at least two.

7. The motor according to claim 1, characterized in that, The air gap is a uniform air gap.

8. The motor according to claim 1, characterized in that, The air gap is a non-uniform air gap.

9. The motor according to claim 1, characterized in that, The stator core includes a stator yoke and a plurality of stator teeth. The plurality of stator teeth are connected at intervals to the stator yoke and enclose a rotor cavity. The rotor core is located inside the rotor cavity, and the air gap is located between the stator teeth and the rotor core.

10. The motor according to claim 1, characterized in that, The stator core comprises multiple core blocks, which are spliced ​​together circumferentially.

11. An electric power steering system, characterized in that, Includes the motor as described in any one of claims 1 to 10.

12. A vehicle, characterized in that, include: The motor as described in any one of claims 1 to 10, or the electric power steering system as described in claim 11.

Images