Magnetic field enhanced hybrid permanent magnet adjustable magnetic flux memory motor

Abstract

The invention discloses a magnetic field enhanced hybrid permanent magnet adjustable magnetic flux memory motor, which comprises a stator, a winding, a rotor and a rotating shaft, the stator is provided with the winding, the rotor is fixed on the rotating shaft, and the rotor is provided with low-coercivity permanent magnets, high-coercivity permanent magnets, V-shaped hybrid permanent magnet grooves and V-shaped high-coercivity permanent magnet straight grooves. And the V-shaped mixed permanent magnet grooves and the V-shaped high-coercivity permanent magnet straight grooves are alternately and uniformly arranged along the circumferential direction of the rotor iron core. According to the invention, the working point of the low-coercivity permanent magnet is improved, and the power density and the overload operation capability of the motor are improved; a loop is formed between the magnetic fluxes of the high-coercivity permanent magnets and the low-coercivity permanent magnets in the V-shaped mixed permanent magnet grooves, so that the air gap flux density can be greatly reduced, and the flux adjusting range of the motor is greatly widened; and the low-coercivity permanent magnet enters an air gap, so that the effect of improving the power density of the motor is achieved.

Description

Technical Field

[0001] The present invention relates to the field of permanent magnet motors, and in particular to a magnetic field enhanced hybrid permanent magnet adjustable flux memory motor. Background Art

[0002] With the growing demand for high-power density and high-efficiency motors in fields such as new energy vehicles, industrial servo systems, and aerospace, permanent magnet synchronous motors (PMSMs) have become the mainstream choice due to their high torque density and high efficiency. Traditional PMSMs often use a single permanent magnet topology (such as surface-mount, internal, or Halbach arrays). These permanent magnets have a fixed flux path, limiting their magnetic field regulation capabilities.

[0003] To improve magnetic field regulation capabilities, existing technologies have proposed series and parallel hybrid magnetic circuit structures. The series hybrid magnetic circuit arranges high-coercivity permanent magnets and low-coercivity permanent magnets in series, changing the operating point of the low-coercivity permanent magnets by adjusting the armature magnetic field. However, the magnetic regulation range of this structure is limited by the strong magnetic coupling between the permanent magnets, and the flux of the high-coercivity permanent magnets is difficult to effectively regulate. The parallel hybrid magnetic circuit sets parallel magnetic circuit branches in the rotor or stator, using electromagnetic excitation or variable reluctance structures to regulate the main magnetic flux. However, the leakage problem between the parallel magnetic circuits is prominent, resulting in a significant reduction in torque density, making it difficult to meet the requirements of high-load scenarios. To this end, we propose a field-enhanced hybrid permanent magnet adjustable flux memory motor. Summary of the Invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a magnetic field enhanced hybrid permanent magnet adjustable flux memory motor.

[0005] Technical solution: The present invention includes a stator, a winding, a rotor and a rotating shaft. The stator is equipped with a winding, and the rotor is fixed on the rotating shaft. The rotor is provided with low-coercive force permanent magnets, high-coercive force permanent magnets, V-shaped hybrid permanent magnet slots and V-shaped high-coercive force permanent magnet straight slots. The V-shaped hybrid permanent magnet slots and V-shaped high-coercive force permanent magnet straight slots are alternately and evenly arranged along the circumferential direction of the rotor core; the openings of the V-shaped hybrid permanent magnet slots are all facing the outside of the rotor, and each V-shaped hybrid permanent magnet slot has a low-coercive force permanent magnet and a high-coercive force permanent magnet placed on both sides. The two permanent magnets on the same side of the V-shaped hybrid permanent magnet slot constitute a parallel hybrid permanent magnet. The permanent magnet unit, the first hybrid permanent magnet unit is a low-coercive force permanent magnet close to the outer side of the rotor and a high-coercive force permanent magnet on the inner side, the second hybrid permanent magnet unit is a low-coercive force permanent magnet close to the inner side of the rotor and a high-coercive force permanent magnet on the outer side, the adjacent hybrid permanent magnet units in adjacent V-shaped hybrid permanent magnet slots are the same, both are first hybrid permanent magnet units or both are second hybrid permanent magnet units; the V-shaped high-coercive force permanent magnet straight slots are located between the low-coercive force permanent magnets in adjacent V-shaped hybrid permanent magnet slots, the V-shaped high-coercive force permanent magnet straight slots close to the outer side of the rotor open towards the inner side of the rotor, and the V-shaped high-coercive force permanent magnet straight slots close to the inner side of the rotor open towards the outer side of the rotor.

[0006] Furthermore, a pair of high coercive force permanent magnets are installed inside the V-shaped high coercive force permanent magnet straight slot.

[0007] Furthermore, the low-coercive-force permanent magnets and the high-coercive-force permanent magnets are magnetized along the width direction thereof, toward the inside or outside of the rotor.

[0008] Furthermore, the first hybrid permanent magnet unit and the second hybrid permanent magnet unit in the V-shaped hybrid permanent magnet slot and the high coercive force permanent magnets on adjacent wings in the V-shaped high coercive force permanent magnet straight slots on both sides thereof form a magnetic pole.

[0009] Furthermore, the low-coercive-force permanent magnet and the high-coercive-force permanent magnet in the first hybrid permanent magnet unit have the same length.

[0010] Furthermore, in the second hybrid permanent magnet unit, the length of the low-coercive force permanent magnet is longer than that of the high-coercive force permanent magnet and is twice the length of the high-coercive force permanent magnet.

[0011] Furthermore, the length of the V-shaped high coercive force permanent magnet straight slot close to the outer side of the rotor is greater than the length of the V-shaped high coercive force permanent magnet straight slot close to the inner side of the rotor.

[0012] Furthermore, the cross sections of the low-coercive force permanent magnet and the high-coercive force permanent magnet are both rectangular.

[0013] Furthermore, the low coercive force permanent magnet is an AlNiCo magnet.

[0014] Furthermore, the high coercive force permanent magnet is a neodymium iron boron magnet.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0016] (1) When the motor of the present invention is running at rated load, the magnetic flux of the high-coercive-force permanent magnet in the V-shaped high-coercive-force permanent magnet straight slot enters the air gap through the low-coercive-force permanent magnet, and the high-coercive-force permanent magnet exerts a magnetizing magnetic potential on the low-coercive-force permanent magnet, thereby improving the working point of the low-coercive-force permanent magnet and increasing the power density and overload operation capability of the motor;

[0017] (2) When a direct-axis demagnetization current pulse is applied to the armature winding of the motor of the present invention, a short circuit phenomenon will occur in the high-coercive-force permanent magnet flux in the V-shaped high-coercive-force permanent magnet straight slot. The required demagnetization magnetic potential does not need to reduce the working point of the high-coercive-force permanent magnet in the V-shaped high-coercive-force permanent magnet straight slot, thereby reducing the amplitude of the required demagnetization current pulse. Secondly, the arrangement of the high-coercive-force permanent magnet and the low-coercive-force permanent magnet in the V-shaped hybrid permanent magnet slot provided by the present invention is effective in the weak magnetic process. In the process, when the demagnetization potential increases continuously and changes the magnetization direction of the low-coercive force permanent magnet, the direction of the demagnetization potential is the same as the magnetization direction of the low-coercive force permanent magnet. The demagnetization potential only passes through the low-coercive force permanent magnet and no longer acts on the high-coercive force permanent magnet, which can reduce the demagnetization risk of the high-coercive force permanent magnet. At the same time, the magnetic flux of the high-coercive force permanent magnet and the low-coercive force permanent magnet in the V-shaped hybrid permanent magnet slot form a loop with each other, which can greatly reduce the air gap flux density and greatly widen the magnetic adjustment range of the motor.

[0018] (3) The arrangement of the V-shaped high-coercive-force permanent magnet straight slots in the motor structure of the present invention is such that when a direct-axis magnetizing current pulse is applied to the armature winding to restore the magnetization level of the low-coercive-force permanent magnet, the magnetic flux of the high-coercive-force permanent magnet in the V-shaped high-coercive-force permanent magnet straight slots will not pass through the high-coercive-force permanent magnet in the V-shaped hybrid permanent magnet slots, but will only enter the air gap through the low-coercive-force permanent magnet, thereby improving the power density of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of a radial cross section of the motor of the present invention;

[0020] Figure 2 Schematic diagram of the magnetization direction of the permanent magnet on the motor rotor of the present invention;

[0021] Figure 3 The magnetic field line distribution of the motor of the present invention when running at rated load;

[0022] Figure 4 The distribution of magnetic lines of force when a direct-axis demagnetizing current pulse is applied to the armature winding of the motor of the present invention during field weakening;

[0023] Figure 5The distribution of magnetic lines of force when a direct-axis magnetizing current pulse is applied to the armature winding of the motor after magnetic weakening to restore the magnetization level of the low-coercive-force permanent magnet;

[0024] Figure 6 The air gap flux density curve when a direct-axis demagnetizing current pulse is applied to the armature winding of the motor to restore the magnetization level of the low-coercive force permanent magnet when the motor is running at rated load;

[0025] Figure 7 The air gap flux density curve when a direct axis demagnetizing current pulse is applied to the armature winding of the motor during field weakening to restore the magnetization level of the low coercive force permanent magnet;

[0026] Figure 8 The air gap flux density curve of the motor when a direct-axis magnetizing current pulse is applied to the armature winding after field weakening to restore the magnetization level of the low-coercive force permanent magnet;

[0027] Figure 9 Schematic diagram of radial cross section of the motor in embodiment 2;

[0028] Figure 10 Schematic diagram of radial cross section of the motor in embodiment three. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0030] Specific implementation method 1: Figure 1 and 2 As shown, the present invention provides a technical solution: a field-enhanced hybrid permanent magnet adjustable flux memory motor, comprising a stator 1, windings 2, a rotor 3, and a rotating shaft 10. The stator 1 is provided with multiple stator teeth on its inner circumference, with the windings 2 embedded between the multiple stator teeth. The rotor 3 is coaxially located within the stator 1 and has internal slots. An air gap is left between the inner wall of the stator 1 and the outer wall of the rotor 3. The thickness of the air gap depends on the motor's power rating, the selected permanent magnet material, and the processing and assembly process of the stator 1 and rotor 3.

[0031] The rotor 3 is provided with low-coercive force permanent magnets 4, high-coercive force permanent magnets 5, V-shaped hybrid permanent magnet slots 8 and V-shaped high-coercive force permanent magnet straight slots 9. The V-shaped hybrid permanent magnet slots 8 and the V-shaped high-coercive force permanent magnet straight slots 9 are alternately and evenly arranged along the circumferential direction of the rotor core; the openings of the V-shaped hybrid permanent magnet slots 8 are all facing the outside of the rotor, and each V-shaped hybrid permanent magnet slot 8 has a low-coercive force permanent magnet 4 and a high-coercive force permanent magnet 5 placed on both sides. The two permanent magnets on the same side of the V-shaped hybrid permanent magnet slot 8 constitute a parallel hybrid permanent magnet unit. The first hybrid permanent magnet unit 6 is close to the outside of the rotor and is a low-coercive force permanent magnet 4, and the inside is a high-coercive force permanent magnet 5. The second hybrid permanent magnet unit 7 is close to the inside of the rotor and is a low-coercive force permanent magnet. The coercive force permanent magnet 4 is provided with a high coercive force permanent magnet 5 on the outside. The adjacent hybrid permanent magnet units in the adjacent V-shaped hybrid permanent magnet slots 8 are the same, that is, the first hybrid permanent magnet unit 6 or the second hybrid permanent magnet unit 7. The V-shaped high coercive force permanent magnet straight slots 9 are located between the low coercive force permanent magnets 4 in the adjacent V-shaped hybrid permanent magnet slots 8. The V-shaped high coercive force permanent magnet straight slots 9 close to the outside of the rotor open toward the inside of the rotor, and the V-shaped high coercive force permanent magnet straight slots 9 close to the inside of the rotor open toward the outside of the rotor. A pair of high coercive force permanent magnets 5 are installed in the V-shaped high coercive force permanent magnet straight slots 9.

[0032] The low-coercive force permanent magnets 4 and the high-coercive force permanent magnets 5 are magnetized along their width direction toward the inside or outside of the rotor; the first hybrid permanent magnet unit 6, the second hybrid permanent magnet unit 7 in the V-shaped hybrid permanent magnet slot 8 and the high-coercive force permanent magnets 5 on the adjacent side wings in the V-shaped high-coercive force permanent magnet straight slots 9 on both sides thereof are combined to form a magnetic pole.

[0033] The low-coercivity permanent magnets 4 and high-coercivity permanent magnets 5 in the first hybrid permanent magnet unit 6 are of the same length. The low-coercivity permanent magnets 4 in the second hybrid permanent magnet unit 7 are longer than the high-coercivity permanent magnets 5, approximately twice the length of the high-coercivity permanent magnets 5. The V-shaped high-coercivity permanent magnet slots 9 near the outside of the rotor are longer than those near the inside of the rotor.

[0034] like Figure 3 and Figure 6 As shown in the figure, when the motor is running at rated load, the magnetism of the high-coercive-force permanent magnets in the V-shaped high-coercive-force permanent magnet straight slots enters the air gap through the low-coercive-force permanent magnets. The high-coercive-force permanent magnets exert a magnetizing magnetic potential on the low-coercive-force permanent magnets. The maximum air gap magnetic flux density is 1.551T, which improves the working point of the low-coercive-force permanent magnets and increases the power density and overload operation capability of the motor.

[0035] like Figure 4 and Figure 7As shown in the figure, when the motor enters the field weakening state, a direct-axis demagnetization current pulse is applied to the armature winding, and the high-coercivity permanent magnet flux c in the V-shaped high-coercivity permanent magnet straight slot will short-circuit. The required demagnetization magnetic potential does not need to lower the working point of the high-coercivity permanent magnet in the V-shaped high-coercivity permanent magnet straight slot, thereby reducing the amplitude of the required demagnetization current pulse. Secondly, during the field weakening process, when the demagnetization magnetic potential continues to increase and changes the magnetization direction of the low-coercivity permanent magnet, the direction of the demagnetization magnetic potential is the same as the magnetization direction of the low-coercivity permanent magnet. The demagnetization magnetic potential d passes through the low-coercivity permanent magnet and no longer acts on the high-coercivity permanent magnet, reducing the risk of demagnetization of the high-coercivity permanent magnet. At the same time, the magnetic flux of the high-coercivity permanent magnet and the low-coercivity permanent magnet in the V-shaped hybrid permanent magnet slot form a loop b with each other, and the air gap flux density is 0.277T, which can significantly reduce the air gap flux density and greatly widen the magnetic adjustment range of the motor.

[0036] like Figure 5 and Figure 8 As shown in the figure, when a direct-axis magnetizing current pulse d is applied to the armature winding to restore the magnetization level of the low-coercive-force permanent magnet, the magnetic flux of the high-coercive-force permanent magnet in the V-shaped high-coercive-force permanent magnet straight slot will not pass through the high-coercive-force permanent magnet in the V-shaped hybrid permanent magnet slot, but only enters the air gap through the low-coercive-force permanent magnet. At this time, the air gap magnetic flux density is 0.960T, which plays a role in improving the power density of the motor.

[0037] Specific implementation method 2: Figure 9 As shown, the difference between this embodiment and embodiment 1 is that a whole low-coercive force permanent magnet 4 and a whole high-coercive force permanent magnet 5 are placed on both sides of each V-shaped hybrid permanent magnet slot 8, the first hybrid permanent magnet unit 6 is a whole low-coercive force permanent magnet 4, and the second hybrid permanent magnet unit 7 is a whole high-coercive force permanent magnet 5.

[0038] Between the low-coercive force permanent magnets 4 in adjacent V-shaped hybrid permanent magnet slots 8 are high-coercive force permanent magnet straight slots 9, which are close to the inner side of the rotor 10. During the weakening process, when the demagnetization magnetic potential changes the magnetization direction of the low-coercive force permanent magnet 4, the demagnetization magnetic potential can pass through the low-coercive force permanent magnet and no longer act on the high-coercive force permanent magnet, thereby reducing the risk of demagnetization of the high-coercive force permanent magnet.

[0039] Specific embodiment three: The difference between this embodiment and embodiment one or embodiment two is that when the V-shaped angle of the V-shaped hybrid permanent magnet slot 8 is 180 degrees, a straight groove is formed, such as Figure 10 As shown, at this time, two low-coercive-force permanent magnets 4 and two high-coercive-force permanent magnets 5 are installed in the slots; the V-shaped high-coercive-force permanent magnet straight slots 9 are still located between the low-coercive-force permanent magnets 4 .

Claims

1. A magnetic field enhanced hybrid permanent magnet adjustable flux memory motor, comprising a stator (1), a winding (2), a rotor (3) and a rotating shaft (10), wherein the stator (1) is provided with the winding (2), and the rotor (3) is fixed on the rotating shaft (10), characterized in that: The rotor (3) is provided with low-coercive force permanent magnets (4), high-coercive force permanent magnets (5), V-shaped hybrid permanent magnet slots (8) and V-shaped high-coercive force permanent magnet straight slots (9), and the V-shaped hybrid permanent magnet slots (8) and V-shaped high-coercive force permanent magnet straight slots (9) are alternately and evenly arranged along the circumferential direction of the rotor core; the openings of the V-shaped hybrid permanent magnet slots (8) are all facing the outside of the rotor, and a low-coercive force permanent magnet (4) and a high-coercive force permanent magnet (5) are placed on the two side wings of each V-shaped hybrid permanent magnet slot (8); the two permanent magnets on the same side wing of the V-shaped hybrid permanent magnet slot (8) constitute a parallel hybrid permanent magnet unit, and the first hybrid permanent magnet unit (6) is close to the outside of the rotor. The invention discloses a low coercive force permanent magnet (4), an inner side of which is a high coercive force permanent magnet (5); a second hybrid permanent magnet unit (7) close to the inner side of the rotor is a low coercive force permanent magnet (4), and an outer side is a high coercive force permanent magnet (5); adjacent hybrid permanent magnet units in adjacent V-shaped hybrid permanent magnet slots (8) are the same, namely, the first hybrid permanent magnet unit (6) or the second hybrid permanent magnet unit (7); the V-shaped high coercive force permanent magnet straight slots (9) are located between the low coercive force permanent magnets (4) in the adjacent V-shaped hybrid permanent magnet slots (8); the V-shaped high coercive force permanent magnet straight slots (9) close to the outer side of the rotor open toward the inner side of the rotor, and the V-shaped high coercive force permanent magnet straight slots (9) close to the inner side of the rotor open toward the outer side of the rotor.

2. The magnetic field enhanced hybrid permanent magnet adjustable flux memory motor according to claim 1, characterized in that: A pair of high-coercive-force permanent magnets (5) are installed inside the V-shaped high-coercive-force permanent magnet straight slot (9).

3. The magnetic field enhanced hybrid permanent magnet adjustable flux memory motor according to claim 1, characterized in that: The low coercive force permanent magnets (4) and the high coercive force permanent magnets (5) are magnetized along the width direction thereof, toward the inside or outside of the rotor.

4. The magnetic field enhanced hybrid permanent magnet adjustable flux memory motor according to claim 1, characterized in that: The first hybrid permanent magnet unit (6), the second hybrid permanent magnet unit (7) in the V-shaped hybrid permanent magnet slot (8) and the high coercive force permanent magnets (5) on adjacent wings in the V-shaped high coercive force permanent magnet straight slots (9) on both sides thereof are combined to form a magnetic pole.

5. The magnetic field enhanced hybrid permanent magnet adjustable flux memory motor according to claim 1, characterized in that: The low-coercive-force permanent magnet (4) and the high-coercive-force permanent magnet (5) in the first hybrid permanent magnet unit (6) have the same length.

6. The magnetic field enhanced hybrid permanent magnet adjustable flux memory motor according to claim 1, characterized in that: The length of the low-coercive force permanent magnet (4) in the second hybrid permanent magnet unit (7) is longer than that of the high-coercive force permanent magnet (5), and the length is twice the length of the high-coercive force permanent magnet (5).

7. The magnetic field enhanced hybrid permanent magnet adjustable flux memory motor according to claim 1, characterized in that: The length of the V-shaped high-coercive-force permanent magnet straight slot (9) close to the outer side of the rotor is greater than the length of the V-shaped high-coercive-force permanent magnet straight slot (9) close to the inner side of the rotor.

8. The magnetic field enhanced hybrid permanent magnet adjustable flux memory motor according to claim 1, characterized in that: The cross sections of the low-coercive force permanent magnet (4) and the high-coercive force permanent magnet (5) are both rectangular.

9. The magnetic field enhanced hybrid permanent magnet adjustable flux memory motor according to claim 1, characterized in that: The low coercive force permanent magnet (4) is an aluminum nickel cobalt magnet.

10. The magnetic field enhanced hybrid permanent magnet adjustable flux memory motor according to claim 1, characterized in that: The high coercive force permanent magnet (5) is a neodymium iron boron magnet.

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