Design method of single-phase motor stator structure assembled with magnetic slot wedge

Abstract

The invention discloses a method for designing a single-phase motor stator structure assembled with magnetic slot wedges. The method comprises the following steps: determining an ideal turn ratio of q coils of a main winding in a phase belt as n1: n2... nq; according to the requirement of the maximum slot full rate, the actual total number of turns in the slot with the maximum number of turns of the main winding is determined, then the ideal number of turns of q coils of the main winding is obtained according to the ideal number of turns ratio, and the ideal number of turns is rounded off to obtain the actual number of turns N1, N2,... Nq of the q coils of the main winding; and the difference between the actual number of turns and the ideal number of turns of q coils of the main winding is calculated as delta N1, delta N2,... delta Nq, and the magnetic slot wedges are installed in the slots with the difference between the actual number of turns and the ideal number of turns being negative. In the single-phase motor, the single-phase motor is provided with the main winding and the auxiliary winding, and the magnetic slot wedge is arranged by mainly combining the difference between the actual turn ratio and the ideal turn ratio of the coil of the main winding, so that the air-gap flux density waveform of the motor tends to be sine, the amplitude of an air-gap harmonic magnetic field is reduced, the THD is reduced, and the efficiency of the motor is improved.

Description

Technical Field

[0001] The invention relates to the technical field of motor design, and in particular to a design method for a single-phase motor stator structure equipped with magnetic slot wedges. Background Art

[0002] At present, the country is promoting energy-saving policies with unprecedented determination and strength, aiming to comprehensively improve energy utilization efficiency, reduce greenhouse gas emissions, and promote green and low-carbon development through a series of innovative measures and strict management. Among them, single-phase asynchronous motors have the advantages of simple structure, small size, stable operation, and optimized stator and rotor structure, single-wire winding characteristics, and efficient coordination of main and auxiliary windings, which significantly reduces energy consumption and improves energy efficiency, becoming the preferred motor type in many application scenarios that require energy conservation and emission reduction. The stator winding of a single-phase asynchronous motor is usually composed of a main winding and an auxiliary starting winding. The main winding is used to generate the main magnetic field, while the auxiliary starting winding is used to create a phase difference in the starting phase to help the motor start. Although the pole and slot parameters of single-phase asynchronous motors may be different, resulting in differences in their winding structure forms, the composition principles of the windings remain the same. That is, through methods such as the paper "Optimal Layout of a Double-Layer Unequal Turn Winding" published by Jin Yang, the ideal turns ratio of the winding is calculated, so that the air gap synthetic magnetomotive force waveform generated by the main winding should be as close to the sine shape as possible, with less harmonic content and low THD. A single-phase asynchronous motor is an AC motor that generates a rotating magnetic field through the stator winding, and the rotor also generates current and forms a magnetic field due to electromagnetic induction. The interaction of the two magnetic fields causes the rotor to rotate continuously. However, in practical applications, due to the influence of factors such as winding distribution, material properties, and manufacturing process, the electric potential and magnetic field of a single-phase asynchronous motor are not completely sinusoidally distributed in space, but have certain harmonic components. Due to the presence of stator slots, the air gap permeability of a single-phase asynchronous motor is uneven. In order to improve this situation and make the air gap magnetic potential closer to the ideal sinusoidal waveform, a magnetic slot wedge can be installed to make the inner surface of the stator smoother, thereby reducing the harmonic components.

[0003] The magnetic slot wedge is a magnetic slot wedge used on the motor. Compared with the ordinary slot wedge, its advantages are mainly reflected in energy saving and consumption reduction, improvement of electromagnetic performance and extension of motor life. Specifically, the magnetic slot wedge can effectively reduce the no-load iron loss of the asynchronous motor through its unique magnetic conductivity, thereby improving the efficiency of the motor and achieving energy saving. In addition, the magnetic slot wedge can also improve the electromagnetic characteristics of the slot, connect the magnetic circuit of the core slot, and have the effect of a closed slot, which can effectively shorten the air gap length, thereby reducing the air gap magnetic resistance and increasing the magnetic field strength accordingly. That is, by reasonably arranging the distribution of the magnetic slot wedge, the air gap magnetic flux can be evenly distributed and the air gap magnetic density waveform is closer to a sine wave. Many scholars have conducted research on magnetic slot wedges, such as the paper "Research and Application of Magnetic Slot Wedges" published by Wu Qingti and the paper "Application of Magnetic Slot Wedges in Energy Saving of Asynchronous Motors" published by Wang Ying. The above research results did not consider the influence of the relative position of the magnetic slot wedge on the magnetic field waveform. It was assumed that the motor magnetomotive force only contained the air gap magnetomotive force, and the same sinusoidal air gap magnetic field waveform could be obtained from the sinusoidal air gap magnetic potential waveform. Therefore, the existing stator structure design of magnetic slot wedges has the following problems:

[0004] Due to the slot fill rate requirements under different processes, the maximum number of turns of the coil in the slot may be different, and the optimal turns ratio of each coil cannot be obtained, that is, the magnetic potential waveform distortion caused by the difference between the actual number of turns and the ideal number of turns is not considered. Using the existing magnetic slot wedge matching method, it may not be possible to obtain the optimal magnetic potential waveform, even if the THD is the smallest. Summary of the invention

[0005] In order to solve the technical problems existing in the background technology, the present invention proposes a design method for a single-phase motor stator structure equipped with magnetic slot wedges.

[0006] The present invention provides a method for designing a single-phase motor stator structure equipped with a magnetic slot wedge, comprising the following steps:

[0007] S1. The stator has a trimmed portion. Determine the number of slots per pole and phase of the motor q = Z / 2pm, the pole pitch of the motor τ = Z / 2p, and determine the spatial electrical angle α of each slot from the center of the magnetic pole i Its sine value sinα i ;

[0008] S2. Determine the ideal turns ratio of the q coils in the main winding of a phase band as n1:n2…n q ;

[0009] S3. According to the requirement of maximum slot full rate, determine the actual total number of turns in the slot with the most turns of the main winding, and then obtain the ideal number of turns of the q coils of the main winding from the ideal turns ratio. Round off the ideal number of turns to obtain the actual number of turns of the q coils of the main winding as N1, N2, ...N q ;

[0010] S4. Calculate the difference between the actual number of turns of the q coils of the main winding and the ideal number of turns as ΔN1, ΔN2, ... ΔN q , install the magnetic slot wedge in the slot where the difference between the actual number of turns and the ideal number of turns is negative.

[0011] In some embodiments, specifically, in step S1: the pitch Y of the coil of the main winding of each slot i , i is the slot number of each slot: when τ is an even number, Y i They are τ-1, τ-3, … 3, 1 respectively; when τ is an odd number, Y i They are τ-1, τ-3,…4,2; α i =90°Y i / τ.

[0012] Specifically, in some embodiments, n1:n2...n q is sinα1:sinα2:...sinα i .

[0013] In some embodiments, preferably, step S3 further includes calculating the number of turns of the coil of the secondary winding.

[0014] Specifically, in some embodiments, the number of turns of the secondary winding is calculated according to the ratio of the number of turns of the primary winding to the number of turns of the secondary winding and the actual number of turns of the primary winding.

[0015] As a further optimized solution of the present invention, it also includes S5: installing non-magnetic slot wedges in stator slots where magnetic slot wedges are not installed.

[0016] In the present invention, a method for designing a stator structure of a single-phase motor equipped with a magnetic slot wedge is proposed. The single-phase motor has a main winding and a secondary winding. The influence of the secondary winding is ignored. The magnetic slot wedge is mainly set in combination with the difference between the actual turns ratio of the coil of the main winding and the ideal turns ratio, so that the motor air gap magnetic flux waveform tends to be sinusoidal, the amplitude of the air gap harmonic magnetic field is reduced, the THD is reduced and the motor efficiency is improved.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of the magnetic slot wedge distribution layout of implementation example 1 of the present invention;

[0019] Figure 2 Schematic diagram of magnetic lines of force of Example 1 of the present invention;

[0020] Figure 3 is a schematic diagram of the magnetic slot wedge distribution layout of implementation example 2 of the present invention;

[0021] Figure 4 Schematic diagram of magnetic lines of force of Example 2 of the present invention;

[0022] Figure 5 It is the finite element simulation result of the three motor models compared in Example 1 of the present invention;

[0023] Figure 6 It is the finite element simulation result of the three motor models compared in Example 2 of the present invention;

[0024] In the figure: 3, the 3rd slot; 5, the 5th slot; 8, the 8th slot; 10, the 10th slot; 15, the 15th slot; 17, the 17th slot; 20, the 20th slot; 22, the 22nd slot. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0026] Implementation case 1: Take a 2.2kW two-pole single-phase asynchronous motor as an example, the trimming part is evenly distributed along the outer circle of the stator. The number of stator slots Z = 24, the number of pole pairs p = 1, the number of stator winding phases m = 2, the stator outer diameter = 165mm, the trimming length = 97.65mm, and the winding uses a 1.06mm copper wire;

[0027] S1. According to the number of stator slots Z, the number of pole pairs p and the number of stator winding phases m, determine the number of slots per pole per phase of the motor q = Z / 2pm, the pole pitch τ = Z / 2p, and the pitch Y of the coils of the main winding of each slot. i , i is the slot number of each slot: when τ is an even number, Y i They are τ-1, τ-3, … 3, 1 respectively; when τ is an odd number, Y i They are τ-1, τ-3,…4,2 respectively. Determine the spatial electrical angle α of each slot from the center of the magnetic pole i =90°Y i / τ and its sine value sinα i .

[0028] Calculation shows that the number of slots per pole per phase is q=6, and the motor pole pitch is τ=12; the pitches of slots 1 to 6 are Y1=11, Y2=9, Y3=7, Y4=5, Y5=3, and Y6=1 respectively; the spatial electrical angles of each slot from the center of the magnetic pole are α1=82.5°, α2=67.5°, α3=52.5°, α4=37.5°, α5=22.5°, and α6=7.5° respectively; their sine values ​​are sinα1=0.991, sinα2=0.924, sinα3=0.793, sinα4=0.608, sinα5=0.383, and sinα6=0.131 respectively;

[0029] S2. Based on the principle that the number of conductors in each slot under each pole is distributed according to the sine law, the ideal turns ratio of the q coils in the main winding of a phase belt is determined as n1:n2…n q , calculate the ideal total turns ratio of each slot of the motor main winding;

[0030] By i = sinα i Calculation shows that the ideal turns ratio of each coil of the main winding in a phase belt is: n1:n2:n3:n4:n5:n6=7.564:7.053:6.053:4.641:2.924:1.

[0031] S3. According to the requirement of maximum slot full rate, determine the actual total number of turns of the main winding in the slot with the largest number of turns, and then obtain the ideal number of turns of the q coils of the main winding from the ideal turns ratio. Round off the ideal number of turns of the q coils of the main winding to obtain the actual number of turns of the q coils of the main winding as N1, N2, ...N q ;

[0032] According to the core and slot size of the stator and rotor and the winding design, the main and auxiliary winding turns ratio is set to 1.25. According to the requirements of the maximum slot fill rate under a specific process, the actual number of turns in the slot with the most turns of the main winding is determined to be 50. The actual number of turns in the slot with the most turns of the secondary winding is 40, which is obtained by iterative calculation using the magnetic circuit method. Using the ideal turns ratio, the main winding turns in the six slots are 50, 47, 40, 31, 19, and 7, respectively, and the secondary winding turns are 40, 37, 32, 25, 15, and 5, respectively.

[0033] S4. Calculate the difference between the actual number of turns of q coils and the ideal number of turns as ΔN1, ΔN2, ... ΔN q , install the magnetic slot wedge in the slot where the difference between the actual number of turns and the ideal number of turns is negative.

[0034] According to the ideal turns ratio of the main winding in a phase band n1:n2:n3:n4:n5:n6=7.564:7.053:6.053:4.641:2.924:1, the ideal turns of the main winding are 50, 46.62, 40.01, 30.68, 19.33, 6.61 respectively. Therefore, the difference between the actual turns of the six coils and the ideal turns is ΔN1=0, ΔN2=0.38, ΔN3=-0.01, ΔN4=0.32, ΔN5=-0.33, ΔN6=0.39 respectively; according to the spatial relationship of the symmetrical winding, magnetic slot wedges are installed in slots 3, 5, 20, and 22 under one pole.

[0035] S5: Install non-magnetic slot wedges in stator slots that are not equipped with magnetic slot wedges.

[0036] In order to verify the beneficial effects of the present invention in the first implementation case, three motor models were established, the first one was a common slot wedge solution, the second one was a magnetic slot wedge solution, and the third one was the present invention solution. Except for the slot wedge solution, the other parameters of the motors were exactly the same. The electromagnetic performance of the three motors at constant torque was calculated using the two-dimensional finite element method. Among them, the magnetic field lines of the third motor model according to the present invention are shown as follows: Figure 2 As shown in the figure, the magnetic lines of force pass through the magnetic slot wedges, while no magnetic lines of force pass through the slots without magnetic slot wedges, which shows that the existence of magnetic slot wedges increases the main magnetic flux, thereby reducing the iron loss caused by the cogging effect when the motor is running. Figure 5 The preferred slot wedge solution of the present invention has an iron loss of 137.75W, and the ordinary slot wedge solution has an iron loss of 141.30W. The iron loss of the present invention is 3.55W lower than that of the ordinary slot wedge solution. The efficiency of the present invention is 0.13% higher than that of the ordinary slot wedge solution. The THD of the present invention is 3.06E-04 less than that of the magnetic slot wedge solution, indicating that the harmonic magnetic potential waveform of the present invention is closer to a sine wave than that of the magnetic slot wedge solution, that is, the harmonic content is less.

[0037] Implementation Case 2: Taking a 2.2kW two-pole single-phase asynchronous motor as an example, the trimming part is evenly distributed along the outer circle of the stator. The number of stator slots Z = 24, the number of pole pairs p = 1, the number of stator winding phases m = 2, the stator outer diameter = 165mm, and the trimming length = 94.86mm. The winding uses a 1.06mm copper wire;

[0038] S1. According to the number of stator slots Z, the number of pole pairs p and the number of stator winding phases m, determine the number of slots per pole per phase of the motor q = Z / 2pm, the pole pitch τ = Z / 2p, and the pitch Y of each slot coil. i , i is the slot number of each slot: when τ is an even number, Y i They are τ-1, τ-3, … 3, 1 respectively; when τ is an odd number, Y iThey are τ-1, τ-3,…4,2 respectively. Determine the spatial electrical angle α of each slot from the center of the magnetic pole i =90°Y i / τ and its sine value sinα i .

[0039] Calculation shows that the number of slots per pole per phase is q=6, and the motor pole pitch is τ=12; the pitches of slots 1 to 6 are Y1=11, Y2=9, Y3=7, Y4=5, Y5=3, and Y6=1 respectively; the spatial electrical angles of each slot from the center of the magnetic pole are α1=82.5°, α2=67.5°, α3=52.5°, α4=37.5°, α5=22.5°, and α6=7.5° respectively; their sine values ​​are sinα1=0.991, sinα2=0.924, sinα3=0.793, sinα4=0.608, sinα5=0.383, and sinα6=0.131 respectively;

[0040] S2. Using the principle that the number of conductors in each slot under each pole is distributed according to the sine law, the ideal turns ratio of q coils in a phase band is determined to be n1:n2…n q , calculate the ideal total turns ratio of each slot in the motor;

[0041] By i = sinα i The ideal turns ratio of each coil in a phase band can be calculated: n1:n2:n3:n4:

[0042] n5:n6=7.564:7.053:6.053:4.641:2.924:1.

[0043] S3. According to the requirement of maximum slot full rate under specific process, determine the actual total number of turns in the slot with the largest number of turns, and then obtain the actual number of turns of q coils as N1, N2, ...N from the ideal turns ratio. q ;

[0044] According to the core and slot size of the stator and rotor and the winding design, the main and auxiliary winding turns ratio is set to 1.25. According to the requirements of the maximum slot fill rate under a specific process, the actual number of turns in the slot with the most turns of the main winding is determined to be 50. The actual number of turns in the slot with the most turns of the secondary winding is 40, which is obtained by iterative calculation using the magnetic circuit method. Using the ideal turns ratio, the main winding turns in the six slots are 50, 47, 40, 31, 19, and 7, respectively, and the secondary winding turns are 40, 37, 32, 25, 15, and 5, respectively.

[0045] S4. Calculate the difference between the actual number of turns of q coils and the ideal number of turns as ΔN1, ΔN2, ... ΔN q , install the magnetic slot wedge in the slot where the difference between the actual number of turns and the ideal number of turns is negative.

[0046] According to the ideal turns ratio n1:n2:n3:n4:n5:n6=7.564:7.053:6.053:4.641:2.924:1 in a phase band, the ideal turns are 50, 46.62, 40.01, 30.68, 19.33, 6.61 respectively. Therefore, the difference between the actual turns of the six coils and the ideal turns is ΔN1=0, ΔN2=0.38, ΔN3=-0.01, ΔN4=0.32, ΔN5=-0.33, ΔN6=0.39 respectively; according to the spatial relationship of the symmetrical winding, magnetic slot wedges are installed in slots 3, 5, 20, and 22 under one pole.

[0047] S5: Install non-magnetic slot wedges in stator slots that are not equipped with magnetic slot wedges.

[0048] In order to verify the beneficial effects of the present invention in the second implementation case, three motor models were established, the first one was a common slot wedge solution, the second one was a magnetic slot wedge solution, and the third one was the present invention solution. Except for the slot wedge solution, the other parameters of the motors were exactly the same. The electromagnetic performance of the three motors at constant torque was calculated using the two-dimensional finite element method. Among them, the magnetic field lines of the third motor model according to the present invention are shown as follows: Figure 4 As shown in the figure, the magnetic lines of force pass through the magnetic slot wedges, while no magnetic lines of force pass through the slots without magnetic slot wedges, which shows that the existence of magnetic slot wedges increases the main magnetic flux, thereby reducing the iron loss caused by the cogging effect when the motor is running. Figure 6 The preferred slot wedge solution of the present invention has an iron loss of 136.34W, and the ordinary slot wedge solution has an iron loss of 139.99W. The iron loss of the present invention is 3.65W lower than that of the ordinary slot wedge solution. The efficiency of the present invention is 0.14% higher than that of the ordinary slot wedge solution. The THD of the present invention is 2.52E-04 less than that of the magnetic slot wedge solution, indicating that the harmonic magnetic potential waveform of the present invention is closer to a sine wave than that of the magnetic slot wedge solution, that is, the harmonic content is less.

[0049] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for designing a single-phase motor stator structure equipped with magnetic slot wedges, characterized in that: The following steps are included S1. The stator has a trimmed portion. Determine the number of slots per pole and phase of the motor q = Z / 2pm, the pole pitch of the motor τ = Z / 2p, and determine the spatial electrical angle α of each slot from the center of the magnetic pole i Its sine value sinα i ; S2. Determine the ideal turns ratio of the q coils in the main winding of a phase band as n1:n2…n q ; S3. According to the requirement of maximum slot full rate, determine the actual total number of turns in the slot with the most turns of the main winding, and then obtain the ideal number of turns of the q coils of the main winding from the ideal turns ratio. Round off the ideal number of turns to obtain the actual number of turns of the q coils of the main winding as N1, N2, ...N q ; S4. Calculate the difference between the actual number of turns of the q coils of the main winding and the ideal number of turns as ΔN1, ΔN2, ... ΔN q , install the magnetic slot wedge in the slot where the difference between the actual number of turns and the ideal number of turns is negative.

2. The method for designing a single-phase motor stator structure equipped with magnetic slot wedges according to claim 1, characterized in that: In step S1: the pitch Y of the coil of the main winding of each slot i , i is the slot number of each slot: when τ is an even number, Y i They are τ-1, τ-3, … 3, 1 respectively; when τ is an odd number, Y i They are τ-1, τ-3,…4,2; α i =90°Y i / τ.

3. The method for designing a single-phase motor stator structure with magnetic slot wedges according to claim 1, characterized in that: In step S2, n1:n2…n q is sinα1:sinα2:...sinα i .

4. The method for designing a single-phase motor stator structure with magnetic slot wedges according to claim 1, characterized in that: Step S3 also includes calculating the number of turns of the coil of the secondary winding.

5. The method for designing a stator structure of a single-phase motor equipped with a magnetic slot wedge according to claim 1, characterized in that: The number of turns of the secondary winding is calculated based on the turns ratio of the primary winding to the secondary winding and the actual number of turns of the primary winding.

6. The method for designing a single-phase motor stator structure with magnetic slot wedges according to claim 1, characterized in that: The method further includes S5: installing non-magnetic slot wedges in stator slots where no magnetic slot wedges are installed.

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