A permanent magnet assisted synchronous reluctance motor rotor structure

Abstract

The present invention relates to a permanent magnet assisted synchronous reluctance motor rotor structure, wherein the rotor core is provided with a plurality of inner and outer U-shaped grooves correspondingly arranged; each inner U-shaped groove is divided into two L-shaped grooves by reinforcing ribs; each two outer U-shaped grooves form a group and are arranged correspondingly with an inner U-shaped groove to form a magnetic space; the inner and outer U-shaped grooves are respectively provided with a second and a first permanent magnet offset to the left, so that the rotor flux is offset, wherein the second permanent magnet of the inner U-shaped groove plays a magnetic conduction role, and corrects the offset angle of the magnetic force line after passing through the first permanent magnet. The permanent magnet torque is improved, and at the same time, the length and width of the first and second permanent magnets are the same, so that the utilization rate of the permanent magnet is increased, and the magnetic force lines are gathered to the left, so that the rotor flux is offset, and the reluctance torque is increased. Under the same torque requirement, the material cost of the motor will be greatly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of synchronous reluctance motors, specifically to a permanent magnet assisted synchronous reluctance motor rotor structure, and more particularly to an electronic rotor structure for improving the permanent magnet torque output of the motor by shifting the permanent magnet flux phase angle. Background Art

[0002] At present, the synchronous reluctance motor has attracted attention in the field of AC speed regulation due to its low cost and good electromagnetic performance, but its torque density and efficiency are generally lower than those of permanent magnet synchronous motors of the same power level. Since the synchronous reluctance motor rotor has no excitation source, its excitation magnetic field comes from the stator armature current and it works completely in an inductive state, so its power factor is lower than that of asynchronous motors and permanent magnet synchronous motors. By inserting auxiliary permanent magnets into the rotor magnetic barrier of the synchronous reluctance motor, not only the torque density and efficiency of the motor can be improved, but also the power factor of the reluctance motor can be improved and the maximum output power of the motor can be increased. Since the amount of inserted permanent magnets is limited, it mainly plays an auxiliary role in improving the performance of the motor. Although the electromagnetic torque contains both reluctance torque and permanent magnet torque, the reluctance torque has a larger component. This type of motor is called a permanent magnet assisted synchronous reluctance motor.

[0003] The torque density, efficiency and power factor of traditional synchronous reluctance motors are relatively low. In addition, since the synchronous reluctance motor rotor (generally referring to the TLA structure) mostly adopts a multi-layer magnetic barrier structure, its magnetic bridge connection part is subject to a large centrifugal force, so the mechanical properties of the synchronous reluctance motor are poor. It is generally used in motor structures with low speed and stator outer diameter within 200mm.

[0004] At present, the motor industry is increasingly concerned about controlling motor costs. In permanent magnet synchronous reluctance motors, improving the utilization rate of permanent magnets and increasing permanent magnet torque are difficult problems that need to be tackled. Therefore, the market is in urgent need of a rotor structure that can fully utilize the performance of rotor permanent magnets and reduce motor costs. Summary of the invention

[0005] The utility model aims to provide an improved permanent magnet assisted synchronous reluctance motor rotor structure, which improves the permanent magnet torque and increases the utilization rate of the permanent magnet by changing the structure of the inner and outer U-shaped grooves and arranging left-biased permanent magnets.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the utility model is: a permanent magnet assisted synchronous reluctance motor rotor structure, including a rotor core, characterized in that: the rotor core is provided with a plurality of inner and outer corresponding U-shaped grooves; the number of inner U-shaped grooves is 2P, P is the number of rotor pole pairs, and each inner U-shaped groove is divided into two L-shaped grooves by reinforcing ribs; the number of outer U-shaped grooves is 4P, P is the number of rotor pole pairs, and every two outer U-shaped grooves form a group and are arranged corresponding to an inner U-shaped groove to form a magnetic space; the inner and outer U-shaped grooves are respectively provided with a second and a first permanent magnet offset to the left, so that the rotor magnetic flux is offset, wherein the second permanent magnet of the inner U-shaped groove plays a magnetic conductive role, and corrects the offset angle of the magnetic field line after passing through the first permanent magnet. The offset angle here refers to: mechanical angle (α1+θ3) / 2, 32° / P≤α1≤48° / P, θ3 is 2°-4°, electrical angle: 22.5°-67.5°, and the no-load magnetic flux density corrected to the center of the first permanent magnet is about 1.0T.

[0007] Preferably, the two L-shaped grooves are symmetrically arranged along the reinforcing rib, the bottom sides of the two L-shaped grooves are parallel to each other, and the width b1 of the reinforcing rib is 1.2 mm-1.5 mm.

[0008] Furthermore, magnetic isolation bridges are provided between the two side ends of the inner U-shaped groove and the two side ends of the outer U-shaped groove and the outer surface of the rotor core, and the center line of each outer U-shaped groove passes through the center point of the rotor core; the arc level of the outer U-shaped groove is α1, 32° / P≤α1≤48° / P; the angle θ1 between the left side line of the outer U-shaped groove and the center line is 20°-30°; the angle θ3 between the two outer U-shaped grooves in each group is 2°-4°, and the length w1 of the magnetic isolation bridge of the outer U-shaped groove is 0.8mm-1mm. The outer U-groove magnetic isolation bridge is 2-3mm radially and 1mm circumferentially away from the first permanent magnet. The length w1 of the magnetic isolation bridge is 0.8mm-1mm and the width is 2-3mm. Its function is to limit the leakage of the permanent magnet through the saturation of the leakage flux at the magnetic bridge. The smaller the width of the magnetic isolation bridge, the more saturated the magnetic flux at the magnetic bridge, and the better the effect of limiting leakage. However, its width cannot be too small, otherwise the mechanical strength of the punching sheet will deteriorate and the service life of the die will be shortened.

[0009] Furthermore, in each rotor pole, a first permanent magnet is inserted into the left U-shaped groove of the two outer U-shaped grooves, and the width h1 of the first permanent magnet is 2.5mm-3mm; a second permanent magnet is inserted into the left L-shaped groove of the inner U-shaped groove, and the length L2 and width h2 of the second permanent magnet are respectively the same as the length L1 and width h1 of the first permanent magnet.

[0010] Compared with the prior art, the technical solution of the utility model not only improves the overall technical solution, but also includes many improvements in details. Specifically, it has the following beneficial effects:

[0011] 1. The improved solution of the utility model is provided with inner and outer U-shaped grooves on the rotor core, and each two outer U-shaped grooves form a group and are arranged corresponding to an inner U-shaped groove to form a magnetic space, and the inner and outer U-shaped grooves are respectively provided with a second and a first permanent magnet offset to the left, so that the rotor magnetic flux is offset, thereby realizing the improvement of the permanent magnet torque, and further improving the output torque of the motor;

[0012] 2. In the technical solution of the utility model, a first permanent magnet is inserted into the left U-shaped groove of the two outer U-shaped grooves; a second permanent magnet is inserted into the left L-shaped groove of the inner U-shaped groove. The length and width of the first and second permanent magnets are the same, which increases the utilization rate of the permanent magnets and gathers the magnetic lines of force to the left, thereby realizing the offset of the rotor flux;

[0013] 3. In the technical solution of the utility model, magnetic isolation bridges are provided between the two side ends of the inner U-shaped groove and the two side ends of the outer U-shaped groove and the outer surface of the rotor core, which further isolates the magnetic field and reduces the passage of magnetic lines and prevents permanent magnet leakage;

[0014] 4. The local setting of the utility model is reasonable, the use effect is good, and it is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the utility model.

[0016] Figure 2 This is a schematic diagram of the rotor punching structure of the utility model.

[0017] Figure 3 This is another structural schematic diagram of the rotor punching of the utility model.

[0018] Figure 4 The figure is a schematic diagram of the structure of a permanent magnet reluctance motor in the prior art.

[0019] Figure 5 The curves of permanent magnet torque and reluctance torque of the prior art rotor structure with respect to position are shown in FIG.

[0020] Figure 6 The curves of permanent magnet torque and reluctance torque of the rotor structure of the utility model with respect to position are compared with the traditional curves.

[0021] Figure 7 The torque vector diagram of the rotor in the prior art is

[0022] Figure 8 The torque vector diagram of the rotor structure of the utility model

[0023] Fig. 9 This is a schematic diagram of the no-load magnetic lines of the motor of the utility model

[0024] Fig.10This is another example schematic diagram of adding rivet holes in the utility model

[0025] Reference numerals:

[0026] 1. Rotor core; 3. Inner U-shaped groove; 4. Outer U-shaped groove; 5. Magnetic isolation bridge; 6. Reinforcement ribs; 7. Rivet holes;

[0027] 21. a first permanent magnet; 22. a second permanent magnet;

[0028] 31. L-shaped groove; 32. L-shaped groove bottom edge;

[0029] 41. Convex corner. DETAILED DESCRIPTION

[0030] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] The utility model provides a permanent magnet assisted synchronous reluctance motor rotor structure, see Figure 1 , including a rotor core, which differs from the prior art in that: the rotor core is provided with a plurality of inner and outer U-shaped grooves correspondingly arranged; the number of the inner U-shaped grooves is 2P, P is the number of rotor pole pairs, and each inner U-shaped groove is divided into two L-shaped grooves by reinforcing ribs; the number of the outer U-shaped grooves is 4P, P is the number of rotor pole pairs, and every two outer U-shaped grooves form a group and are arranged correspondingly to an inner U-shaped groove to form a magnetic space; the inner and outer U-shaped grooves are respectively provided with a second and a first permanent magnet offset to the left, so that the rotor magnetic flux is offset, wherein the second permanent magnet of the inner U-shaped groove plays a magnetic conductive role, corrects the offset angle of the magnetic field line after passing through the first permanent magnet, and makes the offset angle more accurate.

[0032] Furthermore, in each rotor pole, the inner and outer U-shaped grooves are symmetrically arranged along the center line of the magnetic space, that is, the inner and outer U-shaped grooves are divided into two left-right symmetrical parts, the inner U-shaped groove is divided into left-right symmetrical L-shaped grooves, and the outer U-shaped groove includes two left-right symmetrical outer U-shaped grooves. The two inner L-shaped grooves here can just half-surround the two outer U-shaped grooves. When in use, the inner and outer U-shaped grooves are respectively provided with the second and first permanent magnets offset to the left, so that the rotor magnetic flux is offset, thereby achieving an increase in the permanent magnet torque, further improving the output torque of the motor.

[0033] In one embodiment, see Figure 1In the embodiment, the number of inner U-shaped slots is 8, the number of pole pairs of the rotor is 4, and each inner U-shaped slot is divided into two L-shaped slots by reinforcing ribs; the number of outer U-shaped slots is 16, and each two outer U-shaped slots form a group and are arranged corresponding to an inner U-shaped slot to form a magnetic space. The two L-shaped slots are arranged symmetrically along the reinforcing ribs, and the bottom edges of the two L-shaped slots are parallel to each other and on a straight line, and the reinforcing rib width b1 is 1.2mm-1.5mm.

[0034] Furthermore, in each rotor pole, a first permanent magnet is inserted into the left U-shaped groove of the two outer U-shaped grooves, and the width h1 of the first permanent magnet is 2.5mm-3mm; a second permanent magnet is inserted into the left L-shaped groove of the inner U-shaped groove, and the length L2 and width h2 of the second permanent magnet are respectively the same as the length L1 and width h1 of the first permanent magnet. Here, there is an angle between the first and second permanent magnets, and the angle of this angle is 5-10°. The arc of the inner U-shaped groove is α2, where 120° / P≤α2≤144° / P, the bottom length of the two L-shaped grooves is L3, L3-L2-b2≥3mm, and the width of the L-shaped groove flank magnetic barrier is B3, h2≤B3≤h2+2mm, and the preferred value B3=h2+1mm.

[0035] Conventional permanent magnet synchronous motors such as Figure 4 As shown, permanent magnet torque accounts for a large proportion, about 60%, and reluctance torque accounts for about 40%. Figure 5 1 is the permanent magnet torque curve, the function is p*(L md i f i s sinβ), Figure 5 2 is the reluctance torque curve, the function is p*(0.5(L d -L q )i s ^2 sin2β), from the amplitude we can see that the permanent magnet torque is greater than the reluctance torque. Figure 5 Figure 3 is the composite curve of permanent magnet torque and reluctance torque. Figure 7 In the vector diagram, the magnitude of the permanent magnet torque is expressed as I s Projection on the q axis

[0036] The d-axis of the traditional motor is the rotor flux. Due to the offset of the rotor magnetic steel, the permanent magnet reluctance motor of the utility model rotates the magnetic potential counterclockwise ω, as shown in Figure 8 As shown, the rotor flux Rotate counterclockwise by angle ω, where ω=α1 / 2p. After rotation, the rotor flux is The q axis is perpendicular to the rotor flux, I s Projection I on the q axis q As shown in the figure, I q ′=Is sin(β+ω)I q =I s sinβI s sin(β)

[0037] Where 0<ω<current angle θ, then I q ′>I q It can also be seen from the figure that

[0038] Torque formula

[0039]

[0040] Because I q ′>I q , it can be seen from the formula that the motor torque increases. Figure 6 In the figure, the permanent magnet torque curve shifts from 1 to curve 1′ by α1 / 2p, and the reluctance torque curve 2 remains unchanged. The synthetic torque of the two is curve 3′. It can be seen from the figure that the amplitude of curve 3′ is greater than the amplitude of the original curve 3, indicating that the motor torque increases.

[0041] like Figure 2 Figure 3 As shown, the structural constraint formula is:

[0042]

[0043] In the formula, R1 is the inner diameter of the rotor, θ3 is the angle of the magnetic barrier of the U-shaped slot, h3 is the distance from the permanent magnet 1 to the air gap, w1 is the width of the magnetic isolation bridge, α1 is the arc angle of the U-shaped slot, θ1 is the angle of the U-shaped slot edge line, k1 is the gap coefficient between the permanent magnet and the magnetic barrier, which is generally 0.8-1, c1 is the single-side distance between the permanent magnet and the U-shaped slot, which is generally 0.05-0.1

[0044]

[0045] Wherein, R1 is the inner diameter of the rotor, w2 is the width of the magnetic isolation bridge, α2 is the arc angle of the L-shaped slot, B3 is the length of the magnetic isolation bridge of the L-shaped slot, θ2 is the angle between the edge lines of the L-shaped slot, h2 is the thickness of the permanent magnet 2, h4 is the distance from the permanent magnet 2 to the air gap, and b1 is the width of the reinforcing rib.

[0046] In another embodiment, a magnetic isolation bridge is provided between the two side ends of the inner U-shaped groove and the two side ends of the outer U-shaped groove and the outer surface of the rotor core, and the center line of each outer U-shaped groove passes through the center point of the rotor core; the arc level of the outer U-shaped groove is α1, 32° / P≤α1≤48° / P; the angle θ1 between the left side line of the outer U-shaped groove and the center line is 20°-30°, preferably 25 degrees; the angle θ3 between the two outer U-shaped grooves in each group is 2°-4°, preferably 3 degrees, and the length w1 of the magnetic isolation bridge of the outer U-shaped groove is 0.8mm-1mm, preferably 0.88mm.

[0047] The no-load magnetic field line diagram of the utility model is as follows Fig.10 As shown, the two permanent magnets gather the magnetic lines to the left, realizing the deviation of the rotor flux, wherein the permanent magnet 2 plays a magnetic conduction role, pulling back the magnetic lines that deviate to both sides after passing through the permanent magnet 1, making the deviation angle more accurate. The length of b2 is 1-2mm, and the specific length is limited by the position of the outer permanent magnet, and the edges of the two permanent magnets are guaranteed to be in the same straight line as much as possible. Traditional permanent magnets are all in the center or symmetrical about the center. The utility model makes the permanent magnet slot symmetrical about the center, and the permanent magnet is biased to the left, causing the deviation of the rotor flux, thereby improving the permanent magnet torque and increasing the utilization rate of the permanent magnet. The restriction conditions are: the first layer of permanent magnets must be the same length as the second layer of permanent magnets, the first layer must be made into two U-shaped grooves symmetrical structures, and cannot be made into two L-shaped like the second layer, and the magnetic isolation bridge of the left U-shaped groove plays a magnetic isolation role, reducing the magnetic lines passing through and preventing permanent magnet leakage. Further, a circular rivet hole is set between the inner and outer U-shaped grooves of each magnetic space. A balance block is arranged in the right U-shaped groove of the outer layer and the right L-shaped groove of the inner layer.

[0048] In a specific embodiment, the rotor core is provided with a plurality of inner and outer U-shaped grooves correspondingly arranged; the number of the inner U-shaped grooves is 2P, P is the number of pole pairs of the rotor, and each inner U-shaped groove is divided into two L-shaped grooves by reinforcing ribs; the number of the outer U-shaped grooves is 4P, P is the number of rotor pole pairs, and every two outer U-shaped grooves form a group and are arranged corresponding to an inner U-shaped groove to form a magnetic space; the inner and outer U-shaped grooves are respectively provided with a second and a first permanent magnet offset to the left, so that the rotor magnetic flux is offset, wherein the second permanent magnet of the inner U-shaped groove plays a magnetic conductive role, correcting the offset angle of the magnetic field line after passing through the first permanent magnet, so that the offset angle is more accurate.

[0049] Furthermore, two convex corners are arranged on the inner side of each bottom edge of the outer U-shaped groove, and the two bottom corners of the first permanent magnet are placed in the two convex corners, which plays a stabilizing role and can also better guide the direction of the magnetic lines of force and reduce magnetic leakage. For details, please refer to Fig.10 Specifically, the two convex corners form an angle with the bottom edge, the angle is 20-45 degrees, preferably 40 degrees. The outer layer has two U-shaped grooves in a group, and there is a θ3 between them, which is the magnetic barrier angle of the U-shaped groove. The angle θ3 is 2°, and the length w1 of the magnetic isolation bridge of the outer layer U-shaped groove is 0.92mm.

[0050] During the manufacturing process, the connection of the punching sheets of the built-in rotor is mostly in the form of welding or riveting. The riveting process is relatively simple. The rivet holes of the traditional built-in rotor are generally opened below the permanent magnet slots due to concerns about affecting the rotor magnetic circuit. Figure 4As shown, this will cause the inner diameter of the rotor to decrease, and sufficient space must be provided to open the rivet holes. Moreover, due to the influence of the keyway, this space may be further expanded, resulting in an increase in the amount of rotor punching, a waste of space costs, and an increase in the weight of the motor.

[0051] The utility model has a rotor magnetic circuit that is biased to the left. Fig.10 As shown, a rivet hole can be opened in the middle of the two layers of permanent magnet slots, which has four advantages. First, it can further block the magnetic circuit offset by the permanent magnet on the left side, thereby playing a magnetic isolation role; second, it can be used as an auxiliary slot to disperse the centrifugal force of the rotor when it runs at high speed, so that the rotor can withstand a higher speed; third, the position of the rivet hole can be optimized to achieve the purpose of weakening the torque pulsation of the motor; fourth, the rivet hole is more biased towards the outer circle of the rotor, which can effectively prevent the problem of rotor edge warping.

[0052] In the utility model, since the right side of the rotor magnetic steel slot is empty, a balancing block can be placed in when performing dynamic balancing, and the method of drilling holes in the end plate is omitted, so that the processing technology is simpler.

[0053] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and it cannot be determined that the specific implementation of the present invention is limited to the above descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A permanent magnet assisted synchronous reluctance motor rotor structure, comprising a rotor core, characterized in that: The rotor core is provided with a number of inner and outer U-shaped slots correspondingly arranged; the number of inner U-shaped slots is 2P, P is the number of rotor pole pairs, and each inner U-shaped slot is divided into two L-shaped slots by reinforcing ribs; the number of outer U-shaped slots is 4P, P is the number of rotor pole pairs, and every two outer U-shaped slots form a group and are arranged corresponding to an inner U-shaped slot to form a magnetic space; the inner and outer U-shaped slots are respectively provided with a second and a first permanent magnet offset to the left, so that the rotor magnetic flux is offset, wherein the second permanent magnet of the inner U-shaped slot plays a magnetic conductive role, and corrects the offset angle of the magnetic field line after passing through the first permanent magnet; In each magnetic space, a first permanent magnet is inserted into the left U-shaped groove of the two outer U-shaped grooves, and the width h1 of the first permanent magnet is 2.5mm-3mm; a second permanent magnet is inserted into the left L-shaped groove of the inner U-shaped groove, and the length L2 and width h2 of the second permanent magnet are respectively the same as the length L1 and width h1 of the first permanent magnet; the arc level of the inner U-shaped groove is α2, where 120° / P≤α2≤144° / P, the bottom edge length of the two L-shaped grooves is L3, L3-L2-b2≥3mm, and the width of the L-shaped groove flank magnetic barrier is B3, h2≤B3≤h2+2mm.

2. A permanent magnet assisted synchronous reluctance motor rotor structure according to claim 1, characterized in that: The two L-shaped grooves are symmetrically arranged along the reinforcing rib, the bottom sides of the two L-shaped grooves are parallel to each other, and the width b1 of the reinforcing rib is 1.2mm-1.5mm.

3. The permanent magnet assisted synchronous reluctance motor rotor structure according to claim 1, characterized in that: Magnetic isolation bridges are provided between the two side ends of the inner U-shaped groove and the two side ends of the outer U-shaped groove and the outer surface of the rotor core, and the center line of each outer U-shaped groove passes through the center point of the rotor core; the arc level of the outer U-shaped groove is α1, 32° / P≤α1≤48° / P; the angle θ1 between the left side line of the outer U-shaped groove and the center line is 20°-30°; the angle θ3 between the two outer U-shaped grooves in each group is 2°-4°, and the length w1 of the magnetic isolation bridge of the outer U-shaped groove is 0.8mm-1mm.

4. A permanent magnet assisted synchronous reluctance motor rotor structure according to claim 1, characterized in that: A circular rivet hole is arranged between the inner and outer U-shaped grooves of each magnetic space.

5. The permanent magnet assisted synchronous reluctance motor rotor structure according to claim 1, characterized in that: A balance block is arranged in the right U-shaped groove of the outer layer and the right L-shaped groove of the inner layer.

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