A permanent magnet synchronous reluctance motor

Abstract

A permanent magnet synchronous reluctance motor, the motor comprising a stator and a rotor located within the stator, with an air gap between the stator and the rotor, characterized in that: N groups of double-layer air layers are distributed along the outer circumference of the rotor, the double-layer air layer comprising an inner mounting groove and an outer mounting groove that cooperates with the inner mounting groove, the outer mounting groove being partially wrapped within the inner mounting groove; the outer mounting groove comprises a linear mounting groove, the end of the linear mounting groove being a sharpened end having a cutting surface; the present invention has the following beneficial effects: Each direct axis direction is based on two layers of air layers. Since the magnetic conductivity of air is much lower than that of the magnetic core, the reluctance in the direct and quadrature axis magnetic circuits is asymmetric, enabling the motor to have a high saliency ratio (Lq / Ld) and a difference in direct and quadrature axis inductances (Lq - Ld).

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a permanent magnet synchronous reluctance motor, specifically, a permanent magnet synchronous reluctance motor adopting a multi-layer stacked permanent magnet rotor structure. Background Art

[0002] Due to its advantages such as small volume, light weight, high efficiency, large power density, high torque, and convenient control, permanent magnet motors can be applied to electric vehicle drive motors.

[0003] With the development of power electronics technology and control theory, the synchronous reluctance machine (SynRM) is widely used in industrial and agricultural production, transportation, national defense, commerce, household appliances, medical electrical equipment and other fields due to its advantages such as simple structure, easy manufacturing, low cost, and reliable operation.

[0004] At present, the rotor structure of the permanent magnet synchronous reluctance motor is mainly an interior permanent magnet type. Due to its certain reluctance performance, it has become the main rotor structure adopted by new energy vehicle drive motors. However, with the rising price of permanent magnet materials, increasing production costs, and the demand for high-performance drive motors, problems such as magnetic leakage, unremarkable reluctance characteristics, low material utilization rate, and narrow field weakening range in the interior permanent magnet structure motor limit the usage rate of the conventional interior rotor structure. Especially in the ultra-high speed field weakening region, deep field weakening control causes an increase in air gap harmonics, resulting in a significant increase in iron loss, torque ripple, and vibration noise. The permanent magnet is prone to demagnetization under the reverse magnetic field, and the stability of the motor cannot be guaranteed.

[0005] Based on this, it is necessary to invent a new type of permanent magnet synchronous reluctance motor to effectively improve the output torque, power, and power factor of the motor, reduce the back electromotive force in the high-speed field weakening region, and significantly improve the motor speed regulation range. Summary of the Invention

[0006] The object of the present invention is to provide a permanent magnet synchronous reluctance motor. By improving the internal component rotor of the motor and setting multi-layer stacked permanent magnets, the quadrature-axis inductance is made greater than the direct-axis inductance, providing the reluctance characteristics of the motor, thereby effectively improving the output torque, power factor, and efficiency of the motor, and enhancing the motor speed regulation range.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] A permanent magnet synchronous reluctance motor, the motor includes a stator and a rotor located inside the stator, and there is an air gap between the stator and the rotor. It is characterized in that: N groups of double-layer air layers are distributed along the circumferential outer side of the rotor, the double-layer air layer includes an inner mounting groove and an outer mounting groove that cooperates with the inner mounting groove, and the outer mounting groove is semi-wrapped inside the inner mounting groove;

[0009] The outer mounting groove includes a linear mounting groove, and the end of the linear mounting groove is a sharpened end with a cutting surface;

[0010] The inner mounting groove includes two obliquely arranged V-shaped mounting grooves. The ends of the obliquely arranged mounting grooves are sharpened ends with a cutting surface. A first gap is provided between the two obliquely arranged V-shaped mounting grooves, and the first gap forms a magnetic isolation bridge;

[0011] Lateral air holes are respectively arranged on the outer sides of the obliquely arranged V-shaped mounting grooves. Two adjacent double-layer air layers share one lateral air hole. A second gap is provided between the obliquely arranged mounting groove and the lateral air hole;

[0012] N outer weight reduction holes and N inner weight reduction holes are distributed along the inner circumference of the rotor, and N is a positive even number.

[0013] Furthermore, corresponding permanent magnets are arranged in both the inner mounting groove and the outer mounting groove. The length and width of the mounting groove are respectively 0.01 mm larger than the corresponding permanent magnet to prevent the permanent magnet from sliding.

[0014] Furthermore, the end of the sharpened end has an oblique angle or a chamfer.

[0015] Furthermore, the width of the second gap is larger than that of the first gap.

[0016] Furthermore, a certain angle θ1 is formed between the two obliquely arranged V-shaped mounting grooves, and 110° < θ1 < 130°

[0017] Furthermore, the thickness of the permanent magnet along the direct axis direction is h. The thickness h1 of the permanent magnet in the outer mounting groove is greater than the thickness h2 of the permanent magnet in the inner mounting groove, where 0.7 < h1 / h2 < 0.8. The permanent magnet in the outer mounting groove provides a permanent magnetic field excitation source, and the permanent magnet in the inner mounting groove plays an auxiliary excitation role and shares the magnetic field in the reverse direct axis direction during high-speed field weakening to prevent the permanent magnet from permanent demagnetization.

[0018] Furthermore, the rib width between the lateral air hole and the air gap side is r1, and the rib width between the end of the outer mounting groove and the air gap side is r2, and r1 is 0.5 - 0.7r2.

[0019] Furthermore, the outer weight reduction hole is rhombus-shaped with chamfered edges, where the large rhombus angle θ2 = 2*(180° - θ1); the inner weight reduction hole is triangular with chamfered end angles and an arc-shaped bottom edge, and the center of the arc coincides with the center of the motor.

[0020] Compared with the prior art, the technical solution of the present invention includes not only improvements in the overall technical solution but also many improvements in details. Specifically, it has the following beneficial effects:

[0021] 1. In the improvement scheme of the present invention, each group of direct-axis directions is based on two layers of air layers. Since the magnetic conductivity of air is much lower than that of the magnetic core, the magnetic resistance in the direct-axis and cross-axis magnetic circuits is asymmetric, resulting in a higher saliency ratio (Lq / Ld) and a difference in direct-axis and cross-axis inductances (Lq - Ld) of the motor.

[0022] 2. The thickness h1 of the permanent magnet in the outer mounting groove is greater than the thickness h2 of the permanent magnet in the inner mounting groove, where 0.7 < h1 / h2 < 0.8. The permanent magnet in the outer mounting groove provides a permanent magnetic field excitation source, and the permanent magnet in the inner mounting groove plays an auxiliary excitation role and shares the reverse direct-axis magnetic field during high-speed field weakening to prevent the permanent magnet from being permanently demagnetized.

[0023] 3. Lateral air holes are left on the cross-axis side. The gap between the lateral air holes and the air gap side is the rib width r1, and the gap width between the end of the outer mounting groove and the air gap side is the rib width r2, where r1 is 0.5 - 0.7r2. The cross-axis air holes can increase the magnetic resistance of the cross-axis and direct-axis magnetic circuits, mainly reduce the direct-axis inductance, increase the saliency ratio, and when a large current is applied for excitation, the cross-axis magnetic circuit is saturated, and the cross-axis air holes can reduce the rate of decrease of the saliency ratio. At the same time, it can also optimize the magnetic density in the air gap, reduce harmonic components, and reduce the vibration and noise of the motor.

[0024] 4. The outer weight reduction hole is rhombus-shaped with rounded edges at the corners, where the large rhombus angle θ2 = 2*(180° - θ1); the inner weight reduction hole is triangular with rounded end angles and an arc at the bottom, and the center of the arc is the same as the center of the motor, enabling it to improve the output torque of the motor while reducing weight.

[0025] 5. The permanent magnet motor composed of a rotor and a stator with such a special structure is very simple in structure, easy to control, and has a further increased power density. When used in an electric vehicle drive motor, it can further increase the torque of the motor, reduce the weight and volume of the motor, and increase the working stability of the motor. Description of the Drawings

[0026] Figure 1 is the rotor core diagram of the present invention.

[0027] Figure 2 is Figure 1 a partial enlarged view of

[0028] Figure 3 is the structural schematic diagram of the rotor of the present invention after placing the magnetic steel.

[0029] Figure 4 of Figure 3 a partial enlarged schematic diagram of

[0030] Figure 5 is the direct-axis magnetic force line distribution diagram of the present invention.

[0031] Figure 6 This is the cross-axis magnetic field line distribution diagram of the present invention.

[0032] Figure 7 This is the peak operating characteristic curve of the motor.

[0033] Reference numerals:

[0034] 1 Outer mounting groove, 2 Inner mounting groove, 3 Lateral air hole, 4 Outer weight reduction hole, 5 Inner weight reduction hole;

[0035] 11 Linear mounting groove, 12 Sharpened end of outer mounting groove;

[0036] 21 Oblique mounting groove, 22 Sharpened end with cutting surface, 23 Magnetic isolation bridge. Specific embodiments

[0037] Next, the technical solution of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0039] First, some abbreviations or technical terms related to the present invention are defined:

[0040] Reluctance motor: It is a continuously operating electrical drive device, and its structure and working principle are very different from those of traditional AC and DC motors. It does not rely on the interaction of the magnetic fields generated by the stator and rotor windings to generate torque, but relies on the "principle of minimum magnetic resistance" to generate torque.

[0041] Cross and direct axes: The cross axis is also called the q axis, and the direct axis is also called the d axis. They are actually coordinate axes, rather than actual axes. A coordinate system is established on the motor rotor. This coordinate system rotates synchronously with the rotor. The direction of the rotor magnetic field is taken as the d axis, and the direction perpendicular to the rotor magnetic field is taken as the q axis. By converting the mathematical model of the motor into this coordinate system, decoupling of the d axis and the q axis can be achieved, thereby obtaining good control characteristics.

[0042] The present invention provides a permanent magnet synchronous reluctance motor, which mainly consists of a stator, a rotor and a rotating shaft. There is an air gap between the stator and the rotor, and the rotor is supported by the rotating shaft. The stator includes a stator body and a stator winding arranged on the stator body. The motor stator is composed of stator teeth, a stator yoke and stator slots. The stator slots adopt pear-shaped slots, and windings are placed in the slots. The armature winding adopts an integral slot distributed winding. The stator part is prior art and will not be described in detail in this specification.

[0043] Reference Figure 1 In [reference], N groups of double-layer air layers are distributed along the circumferential outer side of the rotor. The double-layer air layer includes an inner mounting groove 2 and an outer mounting groove 1 that cooperates with the inner mounting groove 2. The outer mounting groove 1 is semi-wrapped in the inner mounting groove 2;

[0044] The outer mounting groove 1 includes a straight mounting groove 11, and the end of the straight mounting groove 11 is an outer mounting groove sharpening end 12 with a cutting surface;

[0045] The inner mounting groove 2 includes two obliquely arranged mounting grooves 21 in a V shape. The ends of the obliquely arranged mounting grooves 21 are sharpening ends 22 with a cutting surface. A first gap is provided between the two obliquely arranged mounting grooves in a V shape, and the first gap forms a magnetic isolation bridge 23;

[0046] Lateral air holes 3 are respectively arranged on the outer sides of the obliquely arranged mounting grooves 21 in a V shape. Adjacent two double-layer air layers share one lateral air hole 3. A second gap is provided between the obliquely arranged mounting grooves 21 and the lateral air holes 3;

[0047] N outer weight reduction holes 4 and N inner weight reduction holes 5 are distributed along the circumferential inner side of the rotor, and N is a positive even number.

[0048] Further, corresponding permanent magnets are arranged in both the inner mounting groove and the outer mounting groove. The length and width of the mounting groove are respectively 0.01 mm larger than the corresponding permanent magnet to prevent the permanent magnet from sliding.

[0049] Further, the outer mounting groove sharpening end is an oblique angle protruding from both sides along the straight mounting groove 11. Triangular protrusions extending outward are provided at the outer ends of the two obliquely arranged mounting grooves 21 in a V shape of the inner mounting groove. The end of the triangular protrusion is rounded and faces the outer mounting groove sharpening end. The triangular protrusion part extending outward from the mounting groove 21 can reduce magnetic leakage; the inner sharpening end of the mounting groove 21 is to reduce the magnetic leakage of the permanent magnet in the groove.

[0050] Further, the width of the second gap between the oblique mounting groove 21 and the lateral air hole 3 is greater than the first gap between two V-shaped oblique mounting grooves. The first optimization objective of the intermediate gap is to ensure the rotor structural strength at the motor's limit speed. Because under high-speed conditions, the centrifugal force of the motor is mainly borne by the intermediate air gap and the air gaps on both sides, and the intermediate air gap is the main bearing point. The second objective is to reduce the direct-axis inductance and minimize the leakage magnetic flux. In addition to ensuring the direct-axis inductance and structural strength, the air gap between the mounting groove 21 and the outer air hole 3 also needs to ensure that the quadrature-axis inductance is not reduced too much as much as possible, so as to ensure the salient-pole ratio (Lq / Ld) and (Lq - Ld) required by the motor design. Reducing the direct-axis inductance can reduce the back electromotive force voltage and increase the field-weakening range. The high salient-pole ratio and the difference between the quadrature-axis and direct-axis inductances can increase the inductance reluctance characteristic and the system power factor. Therefore, the width of the second gap is greater than that of the first gap.

[0051] Further, an angle θ1 is formed between two V-shaped oblique mounting grooves, 110° < θ1 < 130°, and the preferred angle is 115° - 123°. The V shape is a basic magnetic flux concentrating structure. With the same amount of permanent magnet, the magnetic field intensity generated by the V-shaped permanent magnet is better, which can make there be no zero magnetic density region in the air gap, so that the air-gap magnetic density has better sinusoidality and can reduce the harmonic content in the air gap.

[0052] Further, the thickness of the permanent magnet along the direct axis direction is h, and the thickness h1 of the permanent magnet in the outer mounting groove is greater than the thickness h2 of the permanent magnet in the inner mounting groove, where 0.7 < h1 / h2 < 0.8. The permanent magnet in the outer mounting groove provides the permanent magnetic field excitation source, and the permanent magnet in the inner mounting groove plays an auxiliary excitation role and shares the magnetic field in the reverse direct-axis direction during high-speed field weakening to prevent the permanent magnet from permanent demagnetization. The thickness of the outer permanent magnet is greater than that of the inner permanent magnet because the outer side, as the main magnetic field, requires sufficient excitation magnetic flux. When the motor operates at full load, the electric load of the motor can be reduced as much as possible. Under the condition of meeting the same magnetic load, the outer layer can use less permanent magnet; the inner layer is mainly for auxiliary excitation, and under the requirements of ensuring the magnetic load, magnetic reluctance performance, demagnetization ability, etc. of the motor, the amount of permanent magnet can be reduced.

[0053] Further, the rib width of the lateral air hole and the air-gap side gap is r1, and the width of the end of the outer mounting groove and the air-gap side gap is r2, and r1 is 0.5 - 0.7r2, preferably r1 = 0.65r2. The quadrature-axis air hole can increase the magnetic reluctance of the quadrature-axis and direct-axis magnetic circuits, mainly reduce the direct-axis inductance, increase the salient-pole ratio. When a large current is applied for excitation, the quadrature-axis magnetic circuit is saturated, and the quadrature-axis air hole can reduce the decreasing rate of the salient-pole ratio. At the same time, it can also optimize the magnetic density in the air gap, reduce the harmonic components, and reduce the vibration and noise of the motor.

[0054] Further, the outer layer weight reduction holes are rhombus-shaped with rounded edges at the rhombus ends, where the large rhombus angle θ2 = 2*(180° - θ1); the inner layer weight reduction holes are triangular with rounded end angles and an arc-shaped base, and the center of the arc coincides with the center of the motor.

[0055] Figure 7 It is the peak operating characteristic curve of the motor. It can be seen that the motor has a relatively wide field weakening at high speeds. Due to the special structure of the motor rotor, within the limited size requirements, the performance of the motor can be exploited as much as possible, the utilization rate of the motor iron core can be increased, and the motor can have high torque output, high power factor, high efficiency, and a wide adjustment range.

[0056] When the present invention is implemented, when the air layer is not dug in the motor, Ld = Lq. When the outer air layer 1 and air layer 2 of the motor are used as the basic reluctance structures of the motor, two layers of air barriers are provided in the direct axis magnetic circuit of the rotor, which can increase the direct axis reluctance and significantly reduce the direct axis inductance, and slightly reduce the quadrature axis inductance; permanent magnets are placed in the installation slots. Since the magnetic permeability of the permanent magnets is the same as that of air and does not change the magnetic reluctance characteristics of the motor, in order to reduce magnetic leakage and the structural strength of the motor, it is necessary to round the ends and sharpen the corners of the installation slots. Through a complex optimization algorithm, with the output torque, efficiency, and power factor as the objective functions, the performance of the motor is optimized. Secondly, this structural combination makes the quadrature axis magnetic circuit mainly concentrated between the first and second layers of magnetic steel, reducing the density of the rotor yoke, thereby reducing the thickness of the rotor yoke. The reduced rotor yoke adopts weight removal and hollowing measures, which can effectively reduce the rotor inertia and improve the dynamic response performance of the rotor. For high-speed motors, their electromagnetic noise needs to be considered. Drilling holes on the q-axis can effectively reduce the air gap harmonics and weaken the electromagnetic noise at the resonance point. An air gap is left in the air holes and the V-shaped air layer to ensure that the reluctance magnetic circuit is not damaged and the quadrature axis inductance will not be reduced too much. In addition, the rotor under this combined structure can effectively weaken the 3rd and 5th harmonics of the motor rotor, with a higher sine wave form of the waveform, and can effectively reduce the core loss.

[0057] The specific embodiments of the present invention have been described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A permanent magnet synchronous reluctance motor, the motor comprising a stator and a rotor located within the stator, with an air gap between the stator and the rotor, characterized in that: There are N groups of double-layer air layers distributed along the outer circumference of the rotor. The double-layer air layer includes an inner mounting groove and an outer mounting groove that cooperates with the inner mounting groove, and the outer mounting groove is semi-wrapped in the inner mounting groove; The outer mounting groove includes a straight mounting groove, and the end of the straight mounting groove is a sharpened end with a cutting surface; The inner mounting groove includes two obliquely arranged mounting grooves in a V shape. The ends of the obliquely arranged mounting grooves are sharpened ends with a cutting surface. There is a first gap between the two obliquely arranged mounting grooves in a V shape, and the first gap forms a magnetic isolation bridge; Lateral air holes are respectively arranged on the outer sides of the obliquely arranged mounting grooves in a V shape. Two adjacent double-layer air layers share one lateral air hole, and there is a second gap between the obliquely arranged mounting groove and the lateral air hole; There are N outer layer weight reduction holes and N inner layer weight reduction holes distributed along the inner circumference of the rotor, and N is a positive even number; An angle θ1 is formed between the two obliquely arranged mounting grooves in a V shape, and 110° < θ1 < 130°; The outer layer weight reduction hole is rhombus-shaped, with rounded edges at the rhombus ends, where the large rhombus angle θ2 = 2*(180° - θ1); the inner layer weight reduction hole is triangular, with rounded end angles, and the bottom edge is an arc, and the center of the arc coincides with the center of the motor.

2. The permanent magnet synchronous reluctance motor according to claim 1, characterized in that Corresponding permanent magnets are arranged in both the inner mounting groove and the outer mounting groove. The length and width of the mounting groove are respectively 0.01 mm larger than the corresponding permanent magnet to prevent the permanent magnet from sliding.

3. A permanent magnet synchronous reluctance motor according to claim 1, characterized in that The end of the sharpened end has an oblique angle or a rounded corner.

4. A permanent magnet synchronous reluctance motor according to claim 1, wherein The width of the second gap is greater than that of the first gap.

5. A permanent magnet synchronous reluctance motor according to claim 1, wherein The thickness of the permanent magnet along the direct axis direction is h. The thickness h1 of the permanent magnet in the outer mounting groove is greater than the thickness h2 of the permanent magnet in the inner mounting groove, where 0.7 < h2 / h1 < 0.

8. The permanent magnet in the outer mounting groove provides a permanent magnetic field excitation source, and the permanent magnet in the inner mounting groove plays an auxiliary excitation role and shares the reverse direct axis magnetic field during high-speed field weakening to prevent the permanent magnet from permanent demagnetization.

6. A permanent magnet synchronous reluctance motor according to claim 1, characterized in that The gap between the lateral air hole and the air gap side is the rib width r1, and the width of the gap between the end of the outer mounting groove and the air gap side is the rib width r2, and r1 is 0.5 - 0.7r2.

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