Self-starting synchronous reluctance motor

Abstract

The utility model introduces a self-starting synchronous reluctance motor. The self-starting synchronous reluctance motor comprises a stator, a rotor core, a cage winding and a rotating shaft, the rotor iron core comprises a plurality of circular rotor punching sheets, the centers of the rotor punching sheets are provided with shaft holes, and the plurality of rotor punching sheets are concentrically stacked on the rotating shaft; a plurality of arc-shaped annular shaft grooves are uniformly arranged on the rotor punching sheet around the shaft hole at intervals, and one longitudinal split groove or two longitudinal split grooves are arranged between the end parts of two adjacent annular shaft grooves in parallel. The rotor punching sheet of the self-starting synchronous reluctance motor provided by the utility model is simple in structure, retains complete and sufficient induction layer arrangement, and only utilizes a very small internal space to implement reluctance on the rotor, so that the motor can generate reluctance torque for synchronous operation, and also has the starting performance of an induction motor; and skewed poles formed by continuous change of rotor punching sheets one by one can be realized on the rotor core, so that the motor can adapt to working conditions not limited to fans and water pumps, and can widely replace an induction motor to save a huge amount of electric energy.

Description

Technical Field

[0001] The utility model relates to the technical field of motors, in particular to a self-starting synchronous reluctance motor. Background Art

[0002] It is well known that, no matter an induction motor or a synchronous reluctance motor, their magnetic circuits are composed of a stator and a rotor, with an air gap between the stator and the rotor. The magnetic circuit of a self-starting synchronous reluctance motor is also composed of a stator, a rotor and an air gap. The rotor core of a self-starting synchronous reluctance motor can be divided into two functional areas, an induction layer and a reluctance layer, from the outside to the inside according to their functions. The main functions corresponding to the two functional areas are: generating electromagnetic torque during startup and generating reluctance torque during synchronous operation. The space where the outermost induction layer is located occupies the closest position to the stator, and is an important place where the rotor core magnetic circuit and the stator core magnetic circuit pass through the air gap to form a closed loop. Therefore, in addition to starting the motor, the induction layer also needs to conduct magnetic flux inward and block the magnetic flux from transmitting along the circumferential direction. The role of conduction; many rotor slots are evenly arranged on the outer side of the rotor core of the induction motor. The outer ends of the rotor slots are wide and the inner ends are long in depth. These rotor slots are filled with cage bars. The cage bars are made of non-ferromagnetic metal materials with good electrical conductivity and have the function of blocking the conduction of magnetic flux along the circumferential direction. Rotor teeth are formed between the rotor slots. The rotor teeth connect the inside of the core and the air gap to conduct magnetic flux. Therefore, the rotor slots, rotor teeth and cage bars of the induction motor are naturally the ideal induction layer setting of the self-starting synchronous reluctance motor. The only problem is that such an induction layer takes up most of the space of the rotor core, and there is very little available space inside as a reluctance layer, and it is completely impossible to use such a small space to arrange multiple layers of conductive bars and multiple layers of magnetic isolation slots.

[0003] The reluctance layer of the rotor core of the self-starting synchronous reluctance motor adopts the form of multi-layer conductive bars and multi-layer magnetic isolation grooves to achieve differentiated direct-axis inductance L d With the quadrature axis inductance L q, and the arrangement of multiple layers of conductive bars and magnetic isolation grooves requires a large space for the magnetic resistance layer. If the motor rotor is set to have the same induction layer depth as that of the induction motor, there will be little space left for the magnetic resistance layer. In order to solve the problem of serious shortage of magnetic resistance layer space, the existing self-starting synchronous magnetic resistance motors generally adopt the method of greatly shortening the depth of the rotor slots, or do not set rotor slots, and use all the space on the rotor core except the shaft hole for arranging conductive bars and magnetic isolation grooves, and only use a magnetic bridge to separate a section of the magnetic isolation groove at the end of the magnetic isolation groove as a rotor slot, or only set a small number of rotor slots at a position where space can be barely squeezed out; however, after occupying the space of the induction layer outward, there is still a problem of insufficient arrangement space, so the magnetic resistance layer also occupies the space of the shaft hole inward, so that the shaft is made very thin, so thin that the installation position of the rotor core, which should be the thickest, is thinner than the shaft neck for installing the bearing, and the shaft has to be modified with a pressure plate structure or a transition structure at both ends of the rotor core, resulting in a complex shaft structure and reduced actual strength.

[0004] The numerous conductors and magnetic isolation slots are arranged in a small space, so the induction layer has to be set very shallow. Although a sufficiently low q-axis inductance is formed on the rotor core, the rotor salient pole ratio The conditions for generating reluctance torque have been improved, but the starting performance of the motor has also deteriorated seriously. There are two influencing factors. One influencing factor is that the reluctance layer becomes shallower, and the total cross-sectional area that can be used to install the cage bars is reduced, resulting in a decrease in the electromagnetic torque generated during starting. Another influencing factor is that when the motor starts, the multi-layer magnetic isolation grooves in the reluctance layer prevent the temporarily non-constant magnetic flux from forming a closed loop, resulting in an even more insufficient electromagnetic torque required for starting. In addition to the weak electromagnetic torque required for the starting process, violent reluctance torque oscillations are also superimposed on the starting torque during the starting process. Due to the significant salient pole ratio When the motor is started, the rotor is not synchronized with the rotating magnetic field, but has to go through a speed-up process from 0 speed to synchronous speed. The rotation direction of the rotor can be established during this period, but the reluctance torque will produce alternating positive and negative oscillations. The reason is that whenever the rotor rotates to a power angle θ between 0° and 90° electrical angle, the reluctance torque is positive, and when the power angle θ exceeds 90° electrical angle, the main magnetic flux will reverse and be injected to the other end of the conductor bar. The difference between the original power angle θ and the 180° electrical angle of half a cycle becomes -90° electrical angle. The rotor needs to go through a process of generating negative reluctance torque from a power angle of -90° electrical angle to 0° electrical angle. At the initial startup, when the rotor speed is 0, the slip rate is 1, and the reluctance torque oscillation frequency is As the speed increases, the oscillation frequency of the reluctance torque decreases, and drops to 0 when the synchronous speed is reached; the depth, slot type, direction and total cross-sectional area of ​​the rotor slots of the self-starting synchronous reluctance motor are very different from those of the induction motor. It is far from being able to start normally under harsh and complex load conditions like an induction motor, and can only be barely used for some load types such as fans and water pumps.

[0005] In addition, the existing self-starting synchronous reluctance motor has the problem of complex rotor punching structure and inability to achieve permanent magnet assistance and pole tilting at the same time; the total tangent length in the punching sheets in the form of multi-layer conductive bars and magnetic isolation grooves is very long, resulting in a high punching force required for processing the punching sheets. Due to the large number of rotor punching sheets required for manufacturing the motor, a lot of energy is consumed; if the rotor poles are tilted, it will inevitably lead to the inability to place permanent magnets in the rotor core, because the space in the rotor core for placing permanent magnets is distorted with the tilting of the poles, and only segmented pole staggering can be adopted; however, segmented pole staggering requires the rotor core to be segmented with the permanent magnets, and segmented pole staggering not only cannot smooth out the impact of alternating switching of stator teeth and slots in a continuously changing form, but also causes the rotor slots in the rotor core for placing cage bars to be misaligned. Utility Model Content

[0006] The purpose of the utility model is to overcome the deficiencies of the prior art and provide a self-starting synchronous reluctance motor with a simple rotor punching structure. The skew poles formed by the continuous change of rotor punchings one by one are realized on the rotor, and a complete and sufficient induction layer setting is retained, so that the motor can generate reluctance torque for synchronous operation and also have the starting performance of an induction motor.

[0007] The technical solution adopted by the utility model is:

[0008] A self-starting synchronous reluctance motor comprises a stator, a rotor core, a cage winding and a rotating shaft; the rotor core is arranged in the stator, and an air gap is left between the outer side of the rotor core and the inner side of the stator; the cage winding comprises an end ring and cage bars;

[0009] The rotor core comprises a plurality of circular rotor punchings, the center of which is provided with an axial hole, and the plurality of rotor punchings are stacked concentrically on a rotating shaft; a plurality of rotor slots are evenly arranged on the rotor punchings along the circumference, cage bars are installed in the rotor slots of the stacked plurality of rotor punchings, and the two ends of the cage bars are respectively connected to end rings; a plurality of arcuate ring shaft grooves are evenly arranged around the axial hole on the rotor punchings, each arcuate ring shaft groove is located on the same circumference concentric with the axial hole, the number of the arcuate ring shaft grooves is the same as the number of motor poles 2P, one or two longitudinal crack grooves are arranged between the ends of two adjacent arcuate ring shaft grooves, and the longitudinal crack grooves are arranged along the radial direction of the axial hole; a magnetic bridge is formed between the inner end of the longitudinal crack groove and the end of the arcuate ring shaft groove, and a magnetic bridge is also formed between the outer end and the rotor slot at the corresponding position; guide bars are formed in the area enclosed by the rotor slot and the arcuate ring shaft groove and the longitudinal crack grooves on both sides of the arcuate ring shaft groove.

[0010] Specifically, the rotor punchings are stacked in a straight pole or oblique pole manner.

[0011] Specifically, the number of rotor slots Q r It is an integer multiple of the number of motor poles 2P.

[0012] Specifically, the outer end of the rotor slot is a closed structure or an open structure, and the open structure of the outer end of the rotor slot forms a rotor slot on the outer circumference of the rotor punching.

[0013] Specifically, the interior of the arc-shaped ring shaft groove is empty or is equipped with a tile-shaped permanent magnet that matches the arc-shaped ring shaft groove.

[0014] More specifically, the center angle θ of the permanent magnet is m 、The center angle of the arc-shaped ring shaft groove θ v The skew angle θ of the length occupied by a single permanent magnet n The relationship is: m ≤θ v -θ n , when the rotor punching is stacked in straight poles θ n is 0°.

[0015] Due to the adoption of the above-mentioned technical solution, the utility model has the following advantages:

[0016] The rotor punching structure of the self-starting synchronous reluctance motor of the utility model is simple, and only one layer of arc-shaped annular shaft groove concentric with the shaft hole is arranged on the periphery of the shaft hole as a magnetic isolation groove, and the proximal ends of two adjacent annular shaft grooves are connected to a longitudinal crack groove together or separately, and the length of the longitudinal crack groove is very short, and it is arranged between the annular shaft groove and the rotor groove; compared with the structure of alternating multi-layer conductive bars and multi-layer magnetic isolation grooves in the prior art, the total length of the tangent in the magnetic resistance layer of the rotor punching of the utility model is only equivalent to one-tenth of the same specification, which can significantly reduce the punching force required for the stamping process. Since the number of rotor punchings required for the production of motors is huge, the utility model can reduce the energy consumption of producing synchronous reluctance motors; and each conductive bar in the rotor magnetic resistance layer together with the annular shaft grooves is a small part of the total length of the tangent in the magnetic resistance layer. The shaft grooves are arranged along the fan ring of the magnetic resistance layer. The space of the magnetic resistance layer is optimally utilized under the limited condition of rarely squeezing the space of the induction layer, and a complete and sufficient induction layer setting is retained. It neither occupies too much space of the induction layer nor needs to reduce the shaft diameter. Only a very small internal space is used to implement magnetic resistance on the rotor, so that the motor can generate magnetic resistance torque and run synchronously, and can also have the starting performance of an induction motor. It can adapt to working conditions not limited to fans and water pumps, and can widely replace induction motors to save huge amounts of electric energy. The ring shaft groove of the utility model can be used to install permanent magnets, and even on the rotor core with skewed poles, tile-shaped permanent magnets can be inserted from both ends, and skewed poles formed by continuous changes of rotor punchings one by one can be realized on the rotor core. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional schematic diagram of the utility model.

[0018] Figure 2 It is an overall schematic diagram of the skew-pole rotor of Example 1 of the utility model.

[0019] Figure 3 It is a schematic diagram of stacking straight poles of rotor punching sheets of the utility model.

[0020] Figure 4 It is a schematic structural diagram of the rotor punching sheet of Example 1 of the utility model.

[0021] Figure 5 It is a schematic diagram of the angular relationship of the permanent magnets installed on the skew-pole rotor of Example 1 of the utility model.

[0022] Figure 6 This is the no-load air gap flux distribution diagram of Example 1 of the utility model.

[0023] Figure 7 It is an overall schematic diagram of the skewed pole rotor of Example 2 of the utility model.

[0024] Figure 8 It is a schematic structural diagram of the rotor punching sheet of Example 2 of the utility model.

[0025] Fig. 9 This is the no-load air gap flux distribution diagram of Example 2 of the utility model.

[0026] Fig.10 It is a relationship diagram between current and speed during the starting process of the motor of the utility model.

[0027] Fig.11 It is a schematic diagram of the cage winding of the utility model.

[0028] In the figure: 1-rotor core, 10-rotor punching sheet, 101-rotor slot, 102-rotor tooth, 103a-longitudinal slot, 103b-arc ring shaft slot, 104-guide bar, 105-shaft hole, 106-magnetic bridge, 107-rotor slot, 21-cage winding, 21a-cage bar, 21b-end ring, 22-permanent magnet, 3-stator, 4-air gap, 5-rotor shaft, d-direct axis, q-quadrature axis, -Magnetic flux lines, θ v The center angle of the arc-shaped ring shaft groove, θ m Permanent magnet center angle, θ n The skew angle of a single permanent magnet.

[0029] In the attached Fig.10In the figure, the ordinate is the motor speed and current, the abscissa is the time, the bold line is the motor steady-state current, the thin line is the motor speed, the reference point Syn is the motor synchronous speed, the reference point Ist is the motor stall current, the reference point In is the motor rated current, and the reference point catch is the capture time point. DETAILED DESCRIPTION

[0030] The present invention is further explained below in conjunction with the accompanying drawings and embodiments, which should not be used to limit the protection scope of the present invention. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention.

[0031] Example 1

[0032] Combined with Figure 1-6 A self-starting synchronous reluctance motor comprises a stator 3, a rotor core 1, a cage winding 21 and a rotating shaft 5; the rotor core 1 is arranged in the stator 3, and an air gap 4 is left between the outer side of the rotor core 1 and the inner side of the stator 3; the cage winding 21 comprises an end ring 21b and cage bars 21a.

[0033] The rotor core 1 includes a plurality of circular rotor punchings 10, the center of which is provided with an axial hole 105, and the plurality of rotor punchings 10 are stacked concentrically on the rotating shaft 5; a plurality of rotor slots 101 are evenly arranged along the circumference of the rotor punchings 10, and the number of rotor slots 101 is Q r The rotor slots 101 of the stacked rotor sheets 10 are provided with cage bars 21a, and the two ends of the cage bars 21a are connected to the end rings 21b respectively; the rotor sheets 10 are provided with a plurality of arcuate annular shaft grooves 103b at even intervals around the shaft hole 105, and each arcuate annular shaft groove 103b is located on the same circumference concentric with the shaft hole 105, and the number of the arcuate annular shaft grooves 103b is the same as the motor pole number 2P, and the number of adjacent arcuate annular shaft grooves 103b is the same as the motor pole number 2P. 03b, a longitudinal crack groove 103a is arranged between the ends, and the longitudinal crack groove 103a is arranged along the radial direction of the shaft hole 105; a magnetic bridge 106 is formed between the inner end of the longitudinal crack groove 103a and the end of the arc-shaped ring shaft groove 103b, and a magnetic bridge 106 is also formed between the outer end and the rotor slot 101 at the corresponding position; a guide bar 104 is formed in the area surrounded by the longitudinal crack groove 103a between the rotor slot 101 and the arc-shaped ring shaft groove 103b and at both ends of the arc-shaped ring shaft groove 103b.

[0034] Preferably, the rotor punching sheets 10 are stacked in a straight pole or oblique pole manner.

[0035] Preferably, the outer end of the rotor slot 101 is a closed structure or an open structure, and the open structure of the outer end of the rotor slot 101 forms a rotor slot 107 on the outer circumference of the rotor punching 10 .

[0036] Preferably, the arc-shaped ring shaft groove 103b is empty or installed with a tile-shaped permanent magnet 22 matching the arc-shaped ring shaft groove 103b;

[0037] Preferably, the center angle θ of the permanent magnet 22 is m , the center angle of the arc-shaped annular shaft groove 103b is θ v The skew angle θ of the length occupied by the single-segment permanent magnet 22 n The relationship is: m ≤θ v -θ n , when the stacking method of the rotor punching sheet 10 is straight pole θ n is 0°.

[0038] Example 2

[0039] like Figure 7 , 8 As shown in FIG. 9 , the difference between Example 2 of the utility model and Example 1 is that in this embodiment, two longitudinal crack grooves 103a are arranged in parallel between the ends of two adjacent arc-shaped ring shaft grooves 103b.

[0040] The synchronous operation principle of the self-starting synchronous reluctance motor of the utility model is as follows: the magnetic resistance layer of the inner part of the induction layer of the rotor core 1 is provided with longitudinal crack grooves 103a and arcuate ring shaft grooves 103b in the magnetic resistance layer for blocking the magnetic flux to form a q-axis with low inductance. If the main magnetic flux is conducted through the q-axis magnetic circuit, it needs to pass through the longitudinal crack grooves 103a or pass through the arcuate ring shaft grooves 103b twice. After the longitudinal crack grooves 103a and the arcuate ring shaft grooves 103b are provided, the induction layer of the rotor core 1 presents a conductive bar 104 for the main magnetic flux to be conducted along the d-axis direction. The main magnetic flux from the stator 3 through the air gap 4 to the rotor core 1 can be merged into the conductive bar 104 through the rotor teeth 102, and is conducted to the other end through the conductive bar 104, shunted by the rotor slots 101, and then passes through the air gap 4 again to return to the stator 3; Figure 6 , Fig. 9 In the figure, we can see the path of the main magnetic flux through the rotor core 1 magnetic circuit, and the higher direct-axis inductance L d With lower quadrature-axis inductance L q The formation of a difference is a necessary condition for the motor to generate magnetic resistance torque. According to the principle of minimum magnetic resistance, the rotor core 1 will continuously adjust its position according to the direction of the magnetic potential of the stator 3 and rotate following the magnetic field generated by the stator 3.

[0041] The self-starting principle of the self-starting synchronous reluctance motor of the utility model: the self-starting function can make the motor directly connected to the industrial frequency AC power for starting. The reluctance method inside the rotor of the utility model is very direct, simple and effective, which brings about a critical benefit. There is no need to arrange a large number of guide bars 104 and slits to occupy a large amount of space, thereby seriously squeezing the outer induction layer space. Therefore, the depth, groove type, direction and total cross-sectional area of ​​the rotor slot 101 that can be set on the rotor core 1 of the utility model are more advantageous, and the direct starting performance of the industrial frequency AC power is significantly improved; such as Fig.10 As shown, when the motor starts, the process from the stationary state to the time when the speed is the same as the rotating magnetic field is an asynchronous operation state. During this period of time, the cage winding 21 distributed on the rotor induction layer will induce the alternating current from the rotating magnetic field of the stator 3. When the alternating current flows through the cage winding 21 in the rotor slot 101, a rotating excitation is formed to generate a rotor magnetic field that is not fixed relative to the rotor core 1. The rotating magnetic field of the stator 3 drives the rotor magnetic field until the motor speed approaches the synchronous speed. At this time, the motor slip will be further eliminated by the synchronous properties of the motor to achieve synchronization.

[0042] The pull-in synchronization principle of the self-starting synchronous reluctance motor of the utility model is as follows: Fig.10 As shown, after the motor starts, when the speed reaches a speed close to the synchronous speed, there is a slip between the synchronous speed and the synchronous speed, but due to the effect of the reluctance torque, this state will not be maintained. According to the minimum reluctance principle, the rotating magnetic field of the stator 3 will immediately capture the rotor, so that a stable and relatively short loop is formed between the rotating magnetic field of the stator 3 and the constant magnetic circuit of the rotor core 1 to achieve minimum reluctance, and the slip is eliminated and the motor is pulled into synchronization. After synchronization, the alternating current in the cage winding 21 on the rotor is reduced to 0, and the motor is driven to rotate only by the reluctance torque, because when the motor is in synchronous operation, the cage winding 21 no longer generates an induced current for excitation.

[0043] The principle of the loss of step of the self-starting synchronous reluctance motor of the utility model is as follows: when the output torque of the motor increases sharply due to a sudden and drastic increase in load, a momentary power failure, etc., the reluctance torque can no longer drive the rotor to maintain synchronous operation, and the rotor overcomes the pulling force of the reluctance torque and lags behind the rotating magnetic field of the stator 3 by more than 90° electrical angle. The range of the positive reluctance torque will cause the motor to lose step, but this will not cause serious faults, because the loss of step will inevitably lead to the formation of slip, and the complete induction layer setting will cause the cage winding 21 to generate an induced current, and the induced current can re-establish a non-constant magnetic field on the rotor core 1 to maintain the asynchronous operation of the motor. After the operating environment is restored, when the motor speed reaches a speed close to the synchronous speed, the rotor is captured by the rotating magnetic field generated by the stator 3 again, and the motor is pulled into synchronization again to resume synchronous operation.

[0044] The parts not described in detail in this utility model are prior art.

[0045] The embodiments selected in this article for the purpose of disclosing the utility model are currently considered to be suitable, but it should be understood that the utility model is intended to include all changes and improvements of the embodiments that belong to the scope of the present concept and utility model.

Claims

1. A self-starting synchronous reluctance motor, comprising a stator, a rotor core, a cage winding and a rotating shaft; the rotor core is arranged in the stator, and an air gap is left between the outer side of the rotor core and the inner side of the stator; the cage winding comprises an end ring and cage bars; characterized in that: The rotor core comprises a plurality of circular rotor punchings, the center of which is provided with an axial hole, and the plurality of rotor punchings are stacked concentrically on a rotating shaft; a plurality of rotor slots are evenly arranged on the rotor punchings along the circumference, cage bars are installed in the rotor slots of the stacked plurality of rotor punchings, and the two ends of the cage bars are respectively connected to end rings; a plurality of arcuate ring shaft grooves are evenly arranged around the axial hole on the rotor punchings, each arcuate ring shaft groove is located on the same circumference concentric with the axial hole, the number of the arcuate ring shaft grooves is the same as the number of motor poles 2P, one or two longitudinal crack grooves are arranged between the ends of two adjacent arcuate ring shaft grooves, and the longitudinal crack grooves are arranged along the radial direction of the axial hole; a magnetic bridge is formed between the inner end of the longitudinal crack groove and the end of the arcuate ring shaft groove, and a magnetic bridge is also formed between the outer end and the rotor slot at the corresponding position; guide bars are formed in the area enclosed by the rotor slot and the arcuate ring shaft groove and the longitudinal crack grooves on both sides of the arcuate ring shaft groove.

2. The self-starting synchronous reluctance motor according to claim 1, characterized in that: The rotor punching sheets are stacked in a straight pole or oblique pole manner.

3. The self-starting synchronous reluctance motor according to claim 1, characterized in that: The number of rotor slots Q r It is an integer multiple of the number of motor poles 2P.

4. The self-starting synchronous reluctance motor according to claim 1, characterized in that: The outer end of the rotor slot is a closed structure or an open structure, and the open structure of the outer end of the rotor slot forms a rotor slot on the outer circumference of the rotor punching sheet.

5. The self-starting synchronous reluctance motor according to claim 1, characterized in that: The interior of the arc-shaped ring shaft groove is empty or is equipped with a tile-shaped permanent magnet matching the arc-shaped ring shaft groove.

6. The self-starting synchronous reluctance motor according to claim 5, characterized in that: The center angle of the permanent magnet is θ m 、The center angle of the arc-shaped ring shaft groove θ v The skew angle θ of the length occupied by a single permanent magnet n The relationship is: m ≤θ v -θ n , when the rotor punching is stacked in straight poles θ n is 0°.

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