Vernier reluctance motor, electric power steering system, and automobile

Abstract

A vernier reluctance motor, comprising a stator and a rotor, wherein a tooth portion of the stator and a tooth portion of the rotor are both of a double salient pole structure; the stator is sleeved on the periphery of the rotor, and an air gap is formed between the stator and the rotor; the stator comprises a plurality of stator teeth and a plurality of stator windings; a two-layer stator winding is wound in a stator slot between every two adjacent stator teeth; each stator winding uses three-phase sinusoidal current with direct-current bias.

Description

Vernier reluctance motor, electric power steering system and automobile

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 5, 2024, with application number 202410247325.3. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of motor design, for example, to a vernier reluctance motor, an electric power steering system and a car. Background Art

[0003] The Electric Power Steering (EPS) system uses an electric power steering motor to directly provide steering assistance, eliminating multiple hydraulic and transmission components. Compared with traditional hydraulic power steering systems, it is more energy-efficient and emission-reducing, and has more flexible assembly, leading a new development direction for the automotive industry.

[0004] Nowadays, electric power steering systems mostly use permanent magnet motors as shown in Figure 1. In permanent magnet synchronous motors, the cost of rare earth permanent magnet materials accounts for a high proportion of the total motor raw material cost, which also leads to the high cost of electric power steering systems. Summary of the Invention

[0005] The present application provides a vernier reluctance motor, the vernier reluctance motor comprising a stator and a rotor;

[0006] The teeth of the stator and the teeth of the rotor both adopt a double-salient pole structure;

[0007] The stator is sleeved on the periphery of the rotor, with an air gap between the stator and the rotor; the stator includes a plurality of stator teeth and a plurality of stator windings; a double layer of the stator windings is wound in the stator slots between the stator teeth, and each of the stator windings uses a three-phase sinusoidal current with a DC bias.

[0008] Optionally, the vernier reluctance motor further comprises: a three-phase winding terminal for supplying power to the plurality of stator windings;

[0009] The three-phase winding terminals include a positive bias terminal of phase A, a negative bias terminal of phase A, a positive bias terminal of phase B, a negative bias terminal of phase B, a positive bias terminal of phase C and a negative bias terminal of phase C; the AC components in the currents provided by the two terminals of the same phase are equal and the DC components are in opposite directions; the phases of the AC components in the currents provided by each phase differ by 120°.

[0010] Optionally, the slot-to-pole ratio of the stator and the rotor is 12 / 10.

[0011] Optionally, the width of the root portion of each stator tooth connected to the stator yoke portion is greater than the width of the end portion adjacent to the corresponding air gap.

[0012] Optionally, the shape of the radial section of each stator tooth is an isosceles trapezoid.

[0013] Optionally, the rotor includes: a rotor yoke and a plurality of rotor teeth, and the width of a root portion of each rotor tooth connected to the rotor yoke is greater than the width of an end portion adjacent to the corresponding air gap.

[0014] Optionally, the shape of the radial section of each rotor tooth is an isosceles trapezoid.

[0015] The present application provides an electric power steering system, which includes a vernier reluctance motor and a controller. The controller is configured to be connected to the vernier reluctance motor and send a control signal and a power signal to the vernier reluctance motor; the vernier reluctance motor is configured to send a feedback signal to the controller and provide steering force to the wheel through the control signal and the power signal.

[0016] The present application provides a car, which includes the electric power steering system, a torque sensor and an auxiliary mechanism, the torque sensor is communicatively connected to the electric power steering system, the electric power steering system is connected to the auxiliary mechanism, the torque sensor is configured to provide a steering force signal to the electric power steering system, and the electric power steering system is configured to provide steering force to the wheels through the steering force signal and the auxiliary mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a schematic structural diagram of a permanent magnet motor for an electric power steering system provided by an embodiment of the present application;

[0018] FIG2 is a schematic structural diagram of a vernier reluctance motor provided in an embodiment of the present application;

[0019] FIG3 is a schematic structural diagram of another vernier reluctance motor provided in an embodiment of the present application;

[0020] FIG4 is a diagram showing torque simulation results of a vernier reluctance motor and a permanent magnet motor of the same size provided in an embodiment of the present application;

[0021] FIG5 is a schematic diagram of the composition of an electric power steering system provided in an embodiment of the present application;

[0022] FIG6 is a schematic diagram of the composition of a car provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in a sequence other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, in addition to the process, method, system, product or equipment comprising a series of steps or units shown in the embodiments of the present application, other processes, methods, systems, products and equipment of this series of steps or units not clearly listed may also be included, or other steps or units inherent to these processes, methods, systems, products or equipment.

[0024] As described in the background technology, electric power steering systems nowadays mostly use permanent magnet motors as shown in FIG1 , and permanent magnets made of rare earth permanent magnet materials are provided in permanent magnet synchronous motors. The applicant has found through research that the cost of permanent magnet materials can account for about 50% of the total cost of the raw materials of the motor, which often leads to a higher total cost of the electric power steering system. Therefore, the "rare earth removal" of the motor in the electric power steering system (hereinafter referred to as the electric power steering motor) has become a more effective cost reduction method. However, conventional non-permanent magnet motors, such as switched reluctance motors or electrically excited synchronous motors, often have the disadvantages of low torque density and large torque pulsation. However, torque density and torque pulsation are indicators that electric power steering motors are concerned about, so conventional non-permanent magnet motors are not applicable. Based on this, the present application proposes a vernier reluctance motor, which greatly reduces the cost of the electric power steering system motor.

[0025] To address the high cost of electric power steering systems, the present application proposes a vernier reluctance motor. FIG2 is a schematic structural diagram of a vernier reluctance motor provided in an embodiment of the present application. Referring to FIG2 , the vernier reluctance motor 100 includes a stator 101 and a rotor 102. The teeth of the stator 101 (hereinafter referred to as stator teeth) and the teeth of the rotor 102 (hereinafter referred to as rotor teeth) both adopt a double-salient pole structure. The stator 101 is sleeved around the outer periphery of the rotor 102, with an air gap 106 between the stator 101 and the rotor 102. The stator 101 includes a plurality of stator teeth 103 and a plurality of stator windings 104. A double layer of stator windings 104 are wound in the stator slots between adjacent stator teeth 103. Each stator winding 104 uses a three-phase sinusoidal current with a DC bias.

[0026] For example, the stator 101 is a salient pole slot structure, provided with a plurality of stator teeth 103, with slots provided between adjacent stator teeth, and two layers of windings distributed in each slot. The stator winding 104 is a three-phase double-layer winding, where one side of a set of coils in the stator winding 104 is embedded in the upper layer of a slot, and the other side is embedded in the lower layer of another slot separated by a certain number of slots from the previous slot. For example, as shown in FIG3 , the stator winding 104 box contains a three-phase double-layer winding. Since it is a concentrated winding, one side A of a set of coils is embedded in the upper layer of a slot, and the other side A of a set of coils is embedded in the lower layer of another slot separated by a certain number of slots from the previous slot. + Embedded on one side of a stator tooth, the other side A - It is embedded on the other side of the stator tooth. It should be noted that the box of the stator winding 104 is only an example and can be marked according to actual needs. As long as the stator winding 104 in the box includes a three-phase double-layer winding, no further restrictions are imposed here. The three-phase double-layer stator winding 104 can select different specific winding methods according to actual needs. No further restrictions are imposed here. For example, the winding method can include wave winding or stacked winding. The three-phase sinusoidal current with a DC bias is a composite current. The current flowing into each coil includes an AC component and a DC component. The application of the composite current allows the stator winding 104 to simultaneously realize the functions of the traditional armature winding and the excitation winding, thereby omitting the actual excitation component or permanent magnet on the rotor 102. This arrangement reduces the copper loss and torque ripple of the motor compared to conventional reluctance motors on the one hand, and reduces the cost compared to permanent magnet motors on the other hand.

[0027] The vernier reluctance motor provided in this embodiment includes a stator and a rotor, and the teeth of the stator and the teeth of the rotor both adopt a double-pole structure; the stator is arranged on the periphery of the rotor, and there is an air gap between the stator and the rotor; the stator includes multiple stator teeth and multiple stator windings; a double-layer stator winding is wound in the stator slots between the multiple stator teeth, and each stator winding adopts a three-phase sinusoidal current with a DC bias, which realizes the addition of a DC excitation magnetic field without setting a separate excitation winding. Such a stator winding power-on scheme design reduces the cost of the motor while ensuring the torque pulsation and torque of the motor are qualified.

[0028] Optionally, Figure 3 is a structural schematic diagram of another vernier reluctance motor provided in an embodiment of the present application. On the basis of the aforementioned embodiment, with reference to Figure 3, the vernier reluctance motor 100 further includes a three-phase winding terminal for powering multiple stator windings; the three-phase winding terminal includes a first-phase positive bias terminal (e.g., A-phase positive bias terminal 305), a first-phase negative bias terminal (e.g., A-phase negative bias terminal 304), a second-phase positive bias terminal (e.g., B-phase positive bias terminal 307), a second-phase negative bias terminal (e.g., B-phase negative bias terminal 306), a third-phase positive bias terminal (e.g., C-phase positive bias terminal 309), and a third-phase negative bias terminal (e.g., C-phase negative bias terminal 308). The AC components in the current provided by the two terminals of the same phase are equal and the DC components are in opposite directions. The phases of the AC components in each phase current of the three-phase winding differ by 120° in sequence. Both the stator teeth 103 and the rotor teeth 303 adopt a double-salient pole structure, and the salient poles are isosceles trapezoidal structures. The width w1 of the root portion of each stator tooth 103 connected to the stator yoke 301 is greater than the width w2 of the end portion adjacent to the air gap corresponding to the stator tooth 103. The rotor includes a rotor yoke 302 and a plurality of rotor teeth 303. The width w3 of the root portion of each rotor tooth 303 connected to the rotor yoke 302 is greater than the width w4 of the end portion adjacent to the air gap corresponding to the rotor tooth 303.

[0029] For example, in order to realize the injection of DC current, the same-phase winding terminals are divided into two groups. For example, the three-phase winding terminals include the first phase winding terminal, the second phase winding terminal and the third phase winding terminal, wherein the first phase winding terminal is divided into A + and A - Two groups, "A" represents the first phase, the second phase winding terminals are divided into B + and B - Two groups, "B" represents the second phase, and the third phase winding terminals are divided into C + and C - Two groups, "C" represents the third phase, "+" represents the DC component in the coil of this group of winding terminals is positive, and "-" represents the DC component in the coil of this group of winding terminals is negative. Based on this, the three-phase winding terminals require six winding terminals to power the three-phase winding terminals. The three-phase sinusoidal current with DC bias provided by a three-phase winding terminal is expressed as:

[0030] Among them, i A+ The first phase positive bias terminal is A + The current provided by the winding, The negative bias end of the first phase is A - The current provided by the winding, The second phase positive bias terminal is B + The current provided by the winding, The negative bias end of the second phase is B - The current provided by the winding, The third phase positive bias terminal is C + The current provided by the winding, The negative bias terminal of the third phase is C - The current provided by the winding, P r is the number of rotor pole pairs; x is the phase angle of the AC component; is the initial phase angle of the current; I ac is the effective value of the current of the AC component (that is, standard sinusoidal AC), which can be expressed as I dc For the DC component, I dc =kI rms Indicates that k is the ratio coefficient, and its value can be related to the size data of the vernier reluctance motor. rms is the effective value of the three-phase sinusoidal current with DC bias.

[0031] For example, the following is a simulation experiment for the permanent magnet motor in the background technology and the vernier reluctance motor 100 proposed in this embodiment. The slot-pole ratio of the stator and the rotor in the vernier reluctance motor 100 is 12 / 10, and the shape of each stator tooth 103 on the radial section of the motor is an isosceles trapezoid, and the shape of each rotor tooth 303 on the radial section of the motor is also an isosceles trapezoid. Table 1 shows a table of size parameters of a vernier reluctance motor provided in an embodiment of the present application. Figure 4 is a torque simulation result diagram of a vernier reluctance motor and a permanent magnet motor of the same size provided in an embodiment of the present application. Referring to Figure 4, this reluctance motor removes the permanent magnet material to save cost, and the simulation results show that its average output torque is 7.1837, and the average torque that a permanent magnet motor of the same size can provide is 7.1795, which are almost equal. Therefore, the vernier reluctance motor proposed in an embodiment of the present application can provide sufficient torque. In addition, the torque pulsation of this vernier reluctance motor can reach 7.5%, which is much smaller than the torque pulsation of about 30% of a conventional reluctance motor, greatly improving the stability of the motor. The motor in the embodiment of the present application has a low cost, and both the output torque and the torque pulsation are suitable for application in electric power steering systems.

[0032] Table 1 Dimensional parameters of a vernier reluctance motor provided in the embodiment of the present application

[0033] The present application also provides an electric power steering system. FIG5 is a schematic diagram illustrating the components of an electric power steering system provided in an embodiment of the present application. Referring to FIG5 , the electric power steering system 500 includes a vernier reluctance motor 100 and a controller 110 according to any of the aforementioned embodiments. The controller 110 is configured to connect to the vernier reluctance motor 100 and send control signals and power signals to the vernier reluctance motor 100. The vernier reluctance motor 100 is configured to send feedback signals to the controller and provide steering force to the wheels via the control signals and power signals.

[0034] The present application also provides an automobile. FIG6 is a schematic diagram of the components of an automobile provided in an embodiment of the present application. Referring to FIG6 , automobile 600 includes an electric power steering system 500 according to any of the aforementioned embodiments, a torque sensor 601, and an auxiliary mechanism 602. The torque sensor 601 is communicatively connected to the electric power steering system 500, which is connected to the auxiliary mechanism 602. The torque sensor 601 is configured to provide a steering force signal to the electric power steering system, and the electric power steering system is configured to provide steering force to the wheels via the steering force signal and the auxiliary mechanism.

[0035] The vernier reluctance motor, electric power steering system and automobile provided in the embodiments of the present application include a stator and a rotor, and the teeth of the stator and the teeth of the rotor both adopt a double-salient pole structure; the stator is arranged on the periphery of the rotor, and there is an air gap between the stator and the rotor; the stator includes a plurality of stator teeth and a plurality of stator windings; a double-layer stator winding is wound in the stator slots between the stator teeth, and each stator winding adopts a three-phase sinusoidal current with a DC bias, which realizes the addition of a DC excitation magnetic field without setting a separate excitation winding. Such a stator winding power-on scheme design reduces the cost of the motor while ensuring that the torque pulsation of the motor is qualified.

Claims

1. A vernier reluctance motor comprising a stator and a rotor; The teeth of the stator and the teeth of the rotor both adopt a double-salient pole structure; The stator is sleeved on the periphery of the rotor, with an air gap between the stator and the rotor; the stator includes a plurality of stator teeth and a plurality of stator windings; a double layer of the stator windings is wound in the stator slots between the stator teeth, and each of the stator windings uses a three-phase sinusoidal current with a DC bias.

2. The vernier reluctance motor according to claim 1, further comprising: three-phase winding terminals for supplying power to the plurality of stator windings; The three-phase winding terminals include a positive bias terminal of phase A, a negative bias terminal of phase A, a positive bias terminal of phase B, a negative bias terminal of phase B, a positive bias terminal of phase C and a negative bias terminal of phase C; the AC components in the currents provided by the two terminals of the same phase are equal and the DC components are in opposite directions; the phases of the AC components in the currents provided by each phase differ by 120°.

3. The vernier reluctance motor according to claim 1, wherein: The slot-pole matching ratio of the stator and the rotor is 12 / 10.

4. The vernier reluctance motor according to any one of claims 1 to 3, wherein: The width of the root portion of each stator tooth connected to the stator yoke portion is greater than the width of the end portion adjacent to the corresponding air gap.

5. The vernier reluctance motor according to claim 4, wherein: The shape of the radial section of each stator tooth is an isosceles trapezoid.

6. The vernier reluctance motor according to any one of claims 1 to 3, wherein: The rotor comprises: a rotor yoke and a plurality of rotor teeth; The width of the root portion of each rotor tooth connected to the rotor yoke is greater than the width of the end portion adjacent to the corresponding air gap.

7. The vernier reluctance motor according to claim 6, wherein: The shape of the radial section of each rotor tooth is an isosceles trapezoid.

8. An electric power steering system, comprising a vernier reluctance motor and a controller according to any one of claims 1 to 7, wherein the controller is configured to be connected to the vernier reluctance motor and to send a control signal and a power signal to the vernier reluctance motor; the vernier reluctance motor is configured to send a feedback signal to the controller and provide steering force to the wheel through the control signal and the power signal.

9. An automobile comprising the electric power steering system, torque sensor and auxiliary mechanism according to claim 8, wherein the torque sensor is communicatively connected to the electric power steering system, the electric power steering system is connected to the auxiliary mechanism, the torque sensor is configured to provide a steering force signal to the electric power steering system, and the electric power steering system is configured to provide steering force to the wheels through the steering force signal and the auxiliary mechanism.

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