Multilayer magnetic barrier type combined magnetic pole bias type permanent magnet synchronous motor

Abstract

The invention discloses a multi-layer magnetic barrier type combined magnetic pole bias permanent magnet synchronous motor, belongs to the technical field of permanent magnet synchronous motors, and aims to solve the problem that electromagnetic torque cannot be superposed to the maximum extent due to the fact that a 45-degree phase difference exists between corresponding current angles when permanent magnet torque and reluctance torque reach peak values in a traditional permanent magnet synchronous motor. The motor comprises a stator and a rotor. A permanent magnet groove penetrating in the axial direction and multiple layers of magnetic barriers communicated with the permanent magnet groove are arranged below each pole of a rotor iron core, and a radial magnetic isolation magnetic barrier extending outwards in the d-axis direction of the rotor divides the permanent magnet groove into two parts which are not communicated symmetrically. The permanent magnet in the groove adopts a combined structure of neodymium iron boron in the center and ferrites on two sides; particularly, the permanent magnets on the left side and the right side of the magnetic isolation magnetic barrier adopt the proportion of asymmetric neodymium iron boron and ferrite permanent magnets, so that the bias effect generated by permanent magnetic flux is not symmetrical about a straight axis any more, the corresponding current angle difference value when the permanent magnetic torque and the reluctance torque reach peak values is reduced, and the torque density is improved.

Description

Technical Field

[0001] The invention relates to a multi-layer magnetic barrier type combined magnetic pole biased permanent magnet synchronous motor, belonging to the technical field of permanent magnet synchronous motors. Background Art

[0002] With the increasing attention paid to environmental protection and energy efficiency around the world, new energy vehicles have gradually attracted people's attention due to their energy-saving and environmentally friendly characteristics. As the core component of the electric vehicle drive system, the drive motor plays a vital role in the performance of electric vehicles. Rare earth permanent magnet synchronous motors have been widely used in the field of new energy vehicles due to their significant advantages of high torque density, high power density and high efficiency. However, due to the extremely uneven global distribution of rare earth resources, the supply chain of rare earth permanent magnets is unstable and the prices fluctuate violently. Therefore, how to optimize motor performance while reducing the amount of rare earth permanent magnet materials has become one of the key strategies to reduce the cost of permanent magnet synchronous motors and promote the sustainable development of the new energy industry.

[0003] The electromagnetic torque of a permanent magnet motor is mainly composed of reluctance torque and permanent magnet torque. In the design of traditional permanent magnet motors, there is a 45° phase difference between the current angles corresponding to the peak values ​​of permanent magnet torque and reluctance torque, which results in insufficient utilization of torque and difficulty in maximizing the superposition of electromagnetic torque, thus causing potential waste of motor performance. In addition, traditional rare earth permanent magnet synchronous motors use neodymium iron boron permanent magnets with a negative intrinsic coercive force temperature coefficient, which are prone to irreversible demagnetization under high temperature conditions. Summary of the invention

[0004] In order to solve the problem that in traditional permanent magnet synchronous motors, there is a 45° phase difference in the current angles corresponding to the peak values ​​of the permanent magnet torque and the reluctance torque, resulting in the inability to maximize the superposition of electromagnetic torque, the present invention provides a multi-layer magnetic barrier type combined pole biased permanent magnet synchronous motor.

[0005] The multi-layer magnetic barrier type combined magnetic pole biased permanent magnet synchronous motor of the present invention comprises a stator and a rotor, wherein the stator is located outside the rotor and a radial air gap is provided between the stator and the rotor; the rotor comprises a rotor core 7, a multi-layer magnetic barrier 3 and permanent magnet slots connected thereto, a radial magnetic barrier 4, a left combined magnetic pole permanent magnet 5 and a right combined magnetic pole permanent magnet 6;

[0006] A permanent magnet slot that penetrates the rotor core 7 in the axial direction and a plurality of connected magnetic barriers 3 are provided under each pole of the rotor core 7. Each layer of permanent magnet slots is perpendicular to the d-axis and is axially symmetrically distributed.

[0007] The radial magnetic barrier 4 extending outward along the rotor d-axis direction symmetrically divides the multi-layer permanent magnet slot into two parts, and the radial magnetic barrier 4 is not connected to the left and right parts of the permanent magnet slot in structure; the left combined magnetic pole permanent magnet 5 is inserted into the permanent magnet slot on the left side of the radial magnetic barrier 4, and the right combined magnetic pole permanent magnet 6 is inserted into the permanent magnet slot on the right side of the radial magnetic barrier 4;

[0008] The left-side combined pole permanent magnet 5 and the right-side combined pole permanent magnet 6 both adopt a structural form of parallel connection of two types of permanent magnets, namely, neodymium iron boron permanent magnet and ferrite permanent magnet, wherein the neodymium iron boron permanent magnet is located at the center, and the ferrite permanent magnets are symmetrically arranged on both sides, and the two types of permanent magnets fit tightly together; by setting the left-side combined pole permanent magnet 5 and the right-side combined pole permanent magnet 6 to have different ratios, the permanent magnet flux bias is no longer symmetrical about the direct axis, thereby reducing the current angle difference corresponding to the peak values ​​of the permanent magnet torque and the reluctance torque, so as to improve the torque density of the motor.

[0009] Preferably, the magnetizing directions of the left combined pole permanent magnet 5 and the right combined pole permanent magnet 6 are both in the d-axis direction, and the magnetizing directions of two adjacent poles are opposite.

[0010] Preferably, the ratio is the ratio of NdFeB permanent magnets to ferrite permanent magnets, and the difference between the ratio of NdFeB permanent magnets in the left combined pole permanent magnet 5 and the ratio of NdFeB permanent magnets in the right combined pole permanent magnet 6 is in the range of 10% to 80%.

[0011] Preferably, the number of layers of the multi-layer magnetic barrier 3 is greater than or equal to 2.

[0012] Preferably, the stator comprises a stator core 1 and a stator winding 2, wherein a plurality of stator tooth slots are evenly distributed on the inner circumference of the stator core 1, and the stator winding 2 is embedded in the stator tooth slots along the circumferential direction.

[0013] Preferably, it further comprises a rotating shaft 8 , and the rotor core 7 is fixed on the rotating shaft 8 .

[0014] Beneficial effects of the present invention: The multi-layer magnetic barrier type combined magnetic pole bias permanent magnet synchronous motor of the present invention adopts an asymmetric ratio of NdFeB and ferrite permanent magnets for the permanent magnets on the left and right sides of the magnetic barrier, so that the bias effect of the permanent magnetic flux is no longer symmetrical about the d axis. This design reduces the amount of rare earth permanent magnets, effectively reduces the current angle difference corresponding to the peak value of the permanent magnet torque and the magnetic resistance torque, improves the anti-demagnetization ability at high temperature, and significantly improves the torque density of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the multi-layer magnetic barrier type combined magnetic pole biased permanent magnet synchronous motor of the present invention;

[0016] Figure 2 It is a schematic diagram of the magnetization direction of the multi-layer magnetic barrier type combined magnetic pole bias type permanent magnet synchronous motor of the present invention;

[0017] Figure 3 It is a schematic diagram of the change of torque with the internal power factor angle before the permanent magnetic field is offset;

[0018] Figure 4 It is a schematic diagram of the change of torque with the internal power factor angle after the permanent magnet magnetic field is offset.

[0019] In the figure, 1 is the stator core, 2 is the armature winding, 3 is the multi-layer magnetic barrier, 4 is the magnetic isolation barrier, 5 is the left combined pole permanent magnet, 6 is the right combined pole permanent magnet, 7 is the rotor core, and 8 is the rotating shaft. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0022] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0023] Specific implementation method 1: The following is combined Figures 1 to 4 The present embodiment is described. The multi-layer magnetic barrier type combined magnetic pole bias permanent magnet synchronous motor described in the present embodiment comprises a stator, a rotor and a rotating shaft 8. The stator is located outside the rotor and there is a radial air gap between the two. The stator comprises a stator core 1 and a stator winding 2. A plurality of stator tooth slots are evenly distributed on the inner circumference of the stator core 1. The stator winding 2 is embedded in these stator tooth slots along the circumferential direction. Figure 1 shown.

[0024] The rotor comprises a rotor core 7, a multi-layer magnetic barrier 3 and permanent magnet slots connected thereto, a radial magnetic barrier 4, a left-side combined magnetic pole permanent magnet 5 and a right-side combined magnetic pole permanent magnet 6; the rotor core 7 is fixed on a rotating shaft 8.

[0025] A permanent magnet slot that penetrates the rotor core 7 in the axial direction and a plurality of connected magnetic barriers 3 are provided under each pole of the rotor core 7. Each layer of permanent magnet slots is perpendicular to the d-axis and is axially symmetrically distributed.

[0026] The radial magnetic barrier 4 extending outward along the rotor d-axis direction symmetrically divides the multi-layer permanent magnet slot into two parts, and the radial magnetic barrier 4 is not connected to the left and right parts of the permanent magnet slot in structure; the left combined magnetic pole permanent magnet 5 is inserted into the permanent magnet slot on the left side of the radial magnetic barrier 4, and the right combined magnetic pole permanent magnet 6 is inserted into the permanent magnet slot on the right side of the radial magnetic barrier 4;

[0027] The left-side combined pole permanent magnet 5 and the right-side combined pole permanent magnet 6 both adopt a structural form of parallel connection of two types of permanent magnets, namely, neodymium iron boron permanent magnet and ferrite permanent magnet, wherein the neodymium iron boron permanent magnet is located at the center, and the ferrite permanent magnets are symmetrically arranged on both sides, and the two types of permanent magnets fit tightly together; by setting the left-side combined pole permanent magnet 5 and the right-side combined pole permanent magnet 6 to have different ratios, the permanent magnet flux bias is no longer symmetrical about the direct axis, thereby reducing the current angle difference corresponding to the peak values ​​of the permanent magnet torque and the reluctance torque, so as to improve the torque density of the motor.

[0028] The magnetization directions of the left combined pole permanent magnet 5 and the right combined pole permanent magnet 6 are both in the d-axis direction, and the magnetization directions of two adjacent poles are opposite. Figure 2 shown.

[0029] The ratio is the ratio of NdFeB permanent magnets to ferrite permanent magnets. The difference between the ratio of NdFeB permanent magnets in the left combined pole permanent magnet 5 and the ratio of NdFeB permanent magnets in the right combined pole permanent magnet 6 is in the range of 10% to 80%. This pole layout can reduce the corner demagnetization of NdFeB permanent magnets at high temperatures, reduce the amount of rare earth permanent magnets, and reduce the cost of the motor. As a result, the permanent magnet flux bias is no longer symmetrical about the direct axis, thereby reducing the current angle difference corresponding to the peak value of the permanent magnet torque and the reluctance torque, achieving the maximum superposition of the reluctance torque and the permanent magnet torque, and improving the torque density of the motor. See Figure 3 and Figure 4 They are the changes of torque with internal power factor angle before and after the permanent magnet magnetic field is offset.

[0030] The number of layers of the multi-layer magnetic barrier 3 is greater than or equal to 2. In each layer structure, the permanent magnet slot is perpendicular to the d-axis, both ends of the permanent magnet slot are connected to a magnetic barrier, and the permanent magnet slot is symmetrically divided into two parts by the radial magnetic barrier 4. The two magnetic barriers and the permanent magnet slot form a U-shaped structure. Take 2 layers as an example, see Figure 1 and Figure 2 Theoretical analysis shows that as the number of magnetic barrier layers increases, the utilization rate of magnetic resistance torque also increases, but it will also increase the complexity of the motor structure. Therefore, when selecting the number of magnetic barrier layers, the motor performance and manufacturing process should be considered comprehensively.

[0031] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A multi-layer magnetic barrier type combined magnetic pole biased permanent magnet synchronous motor, characterized in that: It comprises a stator and a rotor, wherein the stator is located outside the rotor and a radial air gap is provided between the stator and the rotor; the rotor comprises a rotor core (7), a multi-layer magnetic barrier (3) and permanent magnet slots connected thereto, a radial magnetic barrier (4), a left-side combined magnetic pole permanent magnet (5) and a right-side combined magnetic pole permanent magnet (6); A permanent magnet slot that penetrates along the axial direction and a plurality of connected magnetic barriers (3) are arranged under each pole of the rotor core (7), and the permanent magnet slots of each layer are perpendicular to the d-axis and are axially symmetrically distributed. A radial magnetic barrier (4) extending outwardly along the rotor d-axis direction symmetrically divides the multi-layer permanent magnet slot into two parts, and the radial magnetic barrier (4) is not structurally connected to the left and right parts of the permanent magnet slot; the left combined magnetic pole permanent magnet (5) is inserted into the permanent magnet slot on the left side of the radial magnetic barrier (4), and the right combined magnetic pole permanent magnet (6) is inserted into the permanent magnet slot on the right side of the radial magnetic barrier (4); The left-side combined magnetic pole permanent magnet (5) and the right-side combined magnetic pole permanent magnet (6) both adopt a structural form in which two types of permanent magnets, namely, a neodymium iron boron permanent magnet and a ferrite permanent magnet, are connected in parallel, wherein the neodymium iron boron permanent magnet is located at the center, and the ferrite permanent magnets are symmetrically arranged on both sides, and the two types of permanent magnets are tightly fitted; by setting the left-side combined magnetic pole permanent magnet (5) and the right-side combined magnetic pole permanent magnet (6) to have different ratios, the permanent magnetic flux bias is no longer symmetrical about the direct axis, thereby reducing the current angle difference corresponding to the peak value when the permanent magnetic torque and the reluctance torque reach a peak value, so as to improve the torque density of the motor.

2. The multi-layer magnetic barrier type combined magnetic pole bias permanent magnet synchronous motor according to claim 1, characterized in that: The magnetizing directions of the left combined magnetic pole permanent magnet (5) and the right combined magnetic pole permanent magnet (6) are both in the d-axis direction, and the magnetizing directions of two adjacent poles are opposite.

3. The multi-layer magnetic barrier type combined magnetic pole biased permanent magnet synchronous motor according to claim 1, characterized in that: The ratio is the ratio of NdFeB permanent magnets to ferrite permanent magnets, and the difference between the ratio of NdFeB permanent magnets in the left combined magnetic pole permanent magnet (5) and the ratio of NdFeB permanent magnets in the right combined magnetic pole permanent magnet (6) is in the range of 10% to 80%.

4. The multi-layer magnetic barrier type combined magnetic pole biased permanent magnet synchronous motor according to claim 1, characterized in that: The number of layers of the multi-layer magnetic barrier (3) is greater than or equal to 2.

5. The multi-layer magnetic barrier type combined magnetic pole biased permanent magnet synchronous motor according to claim 1, characterized in that: The stator comprises a stator core (1) and a stator winding (2), wherein a plurality of stator tooth slots are evenly distributed on the inner circumference of the stator core (1), and the stator winding (2) is embedded in the stator tooth slots along the circumferential direction.

6. The multi-layer magnetic barrier type combined magnetic pole biased permanent magnet synchronous motor according to claim 5, characterized in that: It also comprises a rotating shaft (8), on which the rotor core (7) is fixed.

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