A synchronous reluctance motor with short-distance unequal-turn concentric windings and a method for obtaining the same

Abstract

The present application provides a synchronous reluctance motor with short-pitch unequal-turn concentric windings and a method for obtaining the same, which belongs to the field of synchronous reluctance motor design. The specific method is: based on a variety of pole slot settings, the winding structure of the motor is modified from a full-pitch or short-pitch equal-turn distributed winding to a short-pitch unequal-turn concentric winding structure; the winding modification method specifically includes the following steps: based on the current pole slot setting, the slot number phase diagram is used to divide the phase bands, and an n-layer winding arrangement table is drawn for the unit motor; the slot full rate of each slot is kept equal, with the goal of reducing the harmonic content in the stator winding magnetomotive force, and the ratio of the number of turns of each coil in each coil group is calculated; the number of conductors per slot and the number of parallel branches are adjusted to obtain the final number of turns configuration. The short-pitch unequal-turn concentric winding scheme proposed in the present application can effectively reduce the stator magnetomotive force and the harmonic content of the air gap magnetic density, thereby effectively reducing the torque pulsation of the motor, and can also reduce the length of the winding end and improve the efficiency of the motor.

Description

Technical Field

[0001] The present application belongs to the field of synchronous reluctance motor design, and more specifically, to a synchronous reluctance motor with short-pitch unequal-turn concentric windings and a method for obtaining the same. Background Art

[0002] Rare earth-free or low rare earth motors are receiving more and more widespread attention. Among them, synchronous reluctance motors have attracted much attention in the field of rare earth-free motors. The magnetic barriers on their rotors cause large differences in the rotor's AC and DC axis reluctance, and then the different reluctances of various parts of the rotor generate magnetic pull to form reluctance torque.

[0003] Since the rotor of the synchronous reluctance motor exhibits high anisotropy, the stator magnetomotive force harmonics and the rotor's multi-layer magnetic barrier structure cause severe motor torque pulsation, resulting in severe vibration and noise, affecting the stable operation of the motor and limiting the application development of the synchronous reluctance motor.

[0004] In previous studies, the main means of reducing the torque pulsation of synchronous reluctance motors include: 1. Optimizing the design of the rotor structure; most of the means focus on optimizing the design of the rotor structure, mainly including optimizing the design of the rotor magnetic barrier structure, using segmented skewed poles in the rotor axial direction, etc., but while reducing the torque pulsation, it will increase the difficulty of design and the complexity of manufacturing and processing. 2. Using auxiliary slots, divided into open stator auxiliary slots and rotor auxiliary slots, but while reducing the torque pulsation, it may cause torque reduction, increase processing difficulty, and affect the mechanical strength of the rotor. 3. Selecting a suitable winding structure; Compared with integer slot distributed windings, fractional slot distributed windings can effectively reduce the torque pulsation of synchronous reluctance motors, but it is necessary to pay attention to selecting suitable pole slot matching. In general, the torque pulsation problem of synchronous reluctance motors still needs further research. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present application is to provide a synchronous reluctance motor with short-pitch unequal-turn concentric windings and a method for obtaining the same, aiming to solve the problem that the synchronous reluctance motor rotor exhibits high anisotropy, the stator magnetomotive force harmonics and the multi-layer magnetic barrier structure of the rotor lead to severe motor torque pulsation, thereby causing serious vibration and noise, which in turn affects the stable operation of the motor.

[0006] To achieve the above-mentioned purpose, in a first aspect, the present application provides a method for obtaining a synchronous reluctance motor with a short-pitch unequal-turn concentric winding, specifically: based on a plurality of different pole slot settings, the winding structure of the motor is modified from a full-pitch or short-pitch equal-turn distributed winding to a short-pitch unequal-turn concentric winding structure, thereby obtaining a winding setting method for a synchronous reluctance motor;

[0007] The method for obtaining the number of turns of a short-distance unequal-turn concentric winding specifically comprises the following steps:

[0008] S1: Based on the current pole slot setting, use the slot number phase diagram to divide the phase band, select the pitch of each coil, and draw an n-layer winding arrangement table for the unit motor; n≥2;

[0009] It should be pointed out here that a coil can consist of one turn or multiple turns, and a coil group is composed of several coils connected in series; a winding consists of multiple coil groups;

[0010] S2: Based on the n-layer winding arrangement table drawn for the unit motor, the slot fill rate of each slot is kept equal, with the goal of reducing the harmonic content and amplitude in the stator winding magnetomotive force, and calculating the ratio between the number of turns of each coil in each coil group;

[0011] S3: Adjust the number of conductors per slot and the number of parallel branches so that the current density, slot fill rate and line load of the motor before and after the modification remain consistent, and obtain the final turns configuration.

[0012] Further preferably, when the motor is a double-layer 36-slot 4-pole motor, S2 specifically includes the following steps:

[0013] Set the number of turns of the three coils from the inside to the outside in each coil group to be b, b+c, and b+c+d respectively;

[0014] According to the equal slot filling rate of each slot, the number of turns of the three coils from the inside to the outside of each coil group is obtained as b, b+c, and b+2c respectively;

[0015] Convert non-equal-component windings into equal-component windings to obtain the winding coefficient of the unit motor;

[0016] Based on the winding coefficient of the unit motor, the value of c / b is calculated with the goal of weakening the 5th, 7th, 11th and 13th stator harmonics, and the ratio of the number of turns of each coil in each coil group is obtained.

[0017] Further preferably, when the motor is a double-layer 36-slot 4-pole motor, the winding coefficient of the unit motor is:

[0018]

[0019] Where, v' is the harmonic order of the unit motor; k w5 =0, k w7 =0.

[0020] Further preferably, the synchronous reluctance motor acquisition method further comprises the following steps:

[0021] The change in the extension length of the winding at the electrode end before and after adjusting the winding structure is calculated, and the motor stack length is increased while keeping the motor volume unchanged.

[0022] Further preferably, the method for obtaining the synchronous reluctance motor also includes a motor wire embedding method, which specifically includes the following steps:

[0023] According to the unequal turns of the concentric winding, determine how many coils with different numbers of turns need to be wound;

[0024] For each parallel branch, a coil with the same number of turns as the innermost coil is embedded in 2q slots;

[0025] Coils are embedded in the other 2 (q-1) slots except the innermost layer, and the number of coil turns is the difference between the number of turns of the second innermost layer coil and the number of turns of the innermost layer coil;

[0026] The coils are embedded in the slots except the innermost and second innermost layers, and the number of coil turns is the difference between the number of turns of the third coil from the inner layer to the outside and the number of turns of the second innermost coil;

[0027] And so on, finally determine the connection method between coils according to the number of parallel branches;

[0028] Where q is the number of slots per pole per phase.

[0029] In a second aspect, the present application provides a synchronous reluctance motor with short-pitch unequal-turn concentric windings, comprising: a rotating shaft, a rotor core, and a stator core arranged in sequence from the inside to the outside; a rotor magnetic barrier is arranged in the rotor core, and a winding is arranged in the stator core;

[0030] The structure of the winding is modified from a full-pitch or short-pitch equal-turn distributed winding to a short-pitch unequal-turn concentric winding structure; the number of turns of the winding is obtained according to the final number of turns obtained by the acquisition method of the synchronous reluctance motor;

[0031] The connection method of the winding is determined according to the number of parallel branches.

[0032] Further preferably, the motor wire embedding is performed according to the above motor wire embedding method.

[0033] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0034] The present application provides a method for obtaining a synchronous reluctance motor with short-pitch unequal-turn concentric windings. The winding structure is modified into a double-layer short-pitch distributed concentric winding structure with unequal pitch and unequal turns under the coordination of multiple different pole slots. The initial number of turns configuration is calculated for the purpose of reducing the low-order harmonics of the stator winding magnetomotive force. Then, by adjusting the number of conductors per slot and the number of parallel branches, it is ensured that after the winding structure is modified, the current density, slot full rate and line load of the motor are respectively consistent with the reference motor, and then the final number of turns configuration is calculated. In addition, in order to improve the output torque of the motor, the stack length of the motor is increased while keeping the motor volume unchanged. In this way, it can be ensured that the harmonic content of the stator magnetomotive force and the harmonic content of the air gap magnetic density are effectively reduced without affecting the average torque and output power of the motor, thereby effectively reducing the rated torque pulsation of the motor and improving the efficiency of the motor. At the same time, in this optimization process, the design of the rotor structure is not involved, the design difficulty is small, and the design cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the arrangement of double-layer windings of a unit motor with 36-slot, 4-pole, unequal pitch, and unequal turns of double-layer short-pitch distributed concentric windings provided in an embodiment of the present application;

[0036] Figure 2 It is a schematic diagram of converting a one-phase non-equal-element winding into an equal-element winding of a unit motor of a double-layer short-distance distributed concentric winding with 36 slots, 4 poles, unequal pitches and unequal turns provided by an embodiment of the present application;

[0037] Figure 3 It is a schematic diagram of a synchronous reluctance motor with 36 slots, 4 poles, unequal pitches, and unequal turns, double-layer short-pitch distributed concentric windings provided in an embodiment of the present application;

[0038] Figure 4 It is a schematic diagram of the connection of a three-phase winding of a double-layer short-distance distributed concentric winding with 36 slots, 4 poles, unequal pitches and unequal turns provided in an embodiment of the present application;

[0039] Figure 5 It is a schematic diagram of the A-phase winding embedding of a double-layer short-distance distributed concentric winding with 36 slots, 4 poles, unequal pitch and unequal turns provided in an embodiment of the present application;

[0040] Figure 6 A schematic diagram showing a comparison of torque ripple simulation of a synchronous reluctance motor before and after optimization provided in an embodiment of the present application;

[0041] Figure 7 A schematic diagram showing a comparison of the efficiency of a synchronous reluctance motor before and after optimization provided in an embodiment of the present application;

[0042] exist Figure 3 In the figure, different numbers represent different structures of synchronous reluctance motors, where:

[0043] 1- stator core; 2- rotor core; 3- armature winding; 4- rotor magnetic barrier; 5- shaft;

[0044] exist Figure 4 In the figure, lines of different thicknesses are used to represent conductors with different numbers of turns. The thickest line represents a coil side of a 65-turn coil, the second thickest line represents a coil side of a 41-turn coil, the second thinnest line represents a coil side of a 17-turn coil, and the thinnest line represents the connecting line between the coils. In addition, the conductor represented by the solid line is located in the upper layer of the slot, and the conductor represented by the dotted line is located in the lower layer of the slot. The number represents the slot number where the corresponding conductor is located, and the arrow represents the direction of the current.

[0045] exist Figure 5 In the figure, the embedding method of the A-phase winding is shown, where the thickest line represents a coil side of a 24-turn coil, the second thickest line represents a coil side of a 17-turn coil, and the thinnest line represents the connection between the coils. In addition, the conductor represented by the solid line is located in the upper layer of the slot, and the conductor represented by the dotted line is located in the lower layer of the slot. The number indicates the slot number where the corresponding conductor is located, and the arrow indicates the direction of the current. When embedding the wire, the coils in the first row are embedded first, then the second row, and finally the third row. DETAILED DESCRIPTION

[0046] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0047] Motor torque pulsation refers to the instantaneous output torque that changes with time during the rotation of the motor, but fluctuates around a certain average value; it is usually expressed as a percentage, which is the ratio of the peak-to-peak value of the output torque to the average value; the peak-to-peak value of the output torque refers to the difference between the highest and lowest values ​​of the output torque within an electrical cycle, which describes the range of variation of the output torque, and the unit is Newton-meter (Nm); the average value of the output torque refers to the average value of the output torque within an electrical cycle, which reflects the concentration trend of the output torque, and the unit is also Newton-meter (Nm); the main sources of torque pulsation in synchronous reluctance motors include the interaction between the stator magnetomotive force and the rotor magnetomotive force and the uneven magnetic resistance caused by the slots on the stator and rotor.

[0048] Before explaining the technical solution of the present application in detail, the data related to the winding structure in the motor is briefly introduced as follows:

[0049] Equal-component windings refer to windings composed of the same coils (same number of turns, same pitch);

[0050] Concentric winding, the winding is composed of coils of different sizes with different pitches in the same pole phase group; all coils in the pole phase group embrace the same center;

[0051] In order to effectively reduce the torque pulsation of the synchronous reluctance motor and improve the efficiency, this embodiment proposes a new winding structure, namely a double-layer short-distance distributed concentric winding structure with unequal pitches and unequal turns; the following is an embodiment.

[0052] The embodiment of the present application provides a method for obtaining a synchronous reluctance motor with 36-slot 4-pole unequal-turn concentric windings, comprising:

[0053] S1: Under the current pole slot matching, the winding structure of the reference motor is modified from a full-pitch equal-turn distributed winding structure to a short-pitch unequal-turn concentric winding structure, and the initial turns configuration is calculated;

[0054] In this embodiment, the winding structure of the reference motor is modified from a full-pitch or short-pitch equal-turn distributed winding structure to a short-pitch unequal-turn concentric winding structure, and the number of turns of each coil is adjusted by an appropriate method so that the winding structure has a lower magnetomotive force harmonic content and a shorter winding end length; therefore, the torque ripple of the synchronous reluctance motor can be effectively reduced and the efficiency can be improved;

[0055] S2: Adjust the number of conductors per slot and the number of parallel branches so that the current density, slot fill rate and line load remain consistent before and after the adjustment, and then obtain the final turns configuration;

[0056] The parameterized model at this time is used as the design method of the synchronous reluctance motor after design.

[0057] The acquisition method of the synchronous reluctance motor provided in this embodiment further includes: in order to improve the output torque of the motor, calculating the change Δl of the extension length of the winding at the electrode end before and after adjusting the winding structure, and increasing the motor stack length while keeping the motor volume unchanged;

[0058] In this embodiment, when considering the motor wire embedding, according to the situation of unequal turns, it is necessary to wind several coils with different numbers of turns; for each parallel branch, firstly, a coil with the same number of turns as the innermost coil is embedded in 2q slots (a coil with the first number of turns), and then a coil with the difference between the number of turns of the second coil from the innermost layer and the number of turns of the innermost coil is embedded in the other 2(q-1) slots except the innermost layer (a coil with the second number of turns), and so on (to the coil with the nth number of turns), and finally the connection mode between the coils is determined according to the number of parallel branches;

[0059] In general, through the above steps, this embodiment can effectively reduce the harmonic content of the stator magnetomotive force and the harmonic content of the air gap magnetic density while ensuring that the motor volume remains unchanged and does not affect the motor output power and average torque, thereby effectively reducing the torque pulsation of the motor and improving the efficiency of the motor; at the same time, it only involves the optimization design of the motor stator winding, but not the optimization design of the rotor, so the design difficulty is small and the cost is low.

[0060] The following takes the design process of a specific 36-slot 4-pole unequal-turn concentric winding synchronous reluctance motor as an example to further verify and illustrate the beneficial effects that can be achieved by this embodiment.

[0061] Based on the design method provided in this embodiment, the winding structure of the motor is modified from a full-pitch equal-turn distributed winding to a short-pitch unequal-turn concentric winding structure. The specific implementation process is as follows:

[0062] First, based on the current pole slot setting, the slot number phase diagram is used to divide the phase band and select the pitch. The pitch of each coil group from the outside to the inside is 8, 6 and 4; then a double-layer winding arrangement table is drawn for the unit motor, such as Figure 1 As shown; suppose the number of turns of the three coils from the inside to the outside of each coil group is b, b+c, b+c+d respectively, and d=c is obtained from the same slot full rate, then the number of turns of the three coils from the inside to the outside of each coil group is b, b+c, b+2c respectively; convert the non-equal component winding into the equal component winding, as shown Figure 2 As shown; the winding coefficient of the calculation unit motor is:

[0063]

[0064] Simplifying, we get:

[0065]

[0066] According to the principle of simultaneously weakening the 5th, 7th, 11th and 13th harmonics, k w5 =0, k w7 =0, so the reasonable c / b value is 1.34-2.53; v' is the harmonic order of the unit motor;

[0067] According to the value of c / b, the turns ratio of the three coils from the inside to the outside of each coil group can be obtained;

[0068] In order to compensate for the influence of the stator winding structure change on the motor performance, the number of conductors per slot is adjusted to 82 and the number of parallel branches is adjusted to 2 to ensure that the current density, slot full rate and line load are consistent with the reference motor; compared with the original 36-slot 4-pole full-pitch winding structure, the end extension length is reduced by 9mm. According to the above method, the motor stack length is increased from 105mm to 114mm to ensure that the output power and output torque of the motor are not affected without changing the motor volume; the final motor structure diagram is shown in Figure 3 As shown, it includes a rotating shaft 5, a rotor core 2 and a stator core 1 which are arranged in sequence from the inside to the outside. A rotor magnetic barrier 4 is arranged in the rotor core 1, and an armature winding 3 is arranged in the stator core 1. The three-phase winding connection diagram is shown in FIG. Figure 4 shown.

[0069] A phase embedded line diagram Figure 5As shown, according to the situation of unequal turns, two coils with different numbers of turns, namely 17 turns and 24 turns, need to be wound. Taking phase A as an example, first embed the 17-turn coil edge in the upper layer of slots 1, 2, 3, 10, 11, 12, 19, 20, 21, 28, 29, and 30 and the lower layer of slots 7, 8, 9, 16, 17, 18, 25, 26, 27, 34, 35, and 36, embed the 24-turn coil edge in the upper layer of slots 1, 2, 10, 11, 19, 20, 28, and 29 and the lower layer of slots 8, 9, 17, 18, 26, 27, 35, and 36, embed the 24-turn coil edge in the upper layer of slots 1, 10, 19, and 28 and the lower layer of slots 9, 18, 27, and 36, and finally determine the connection method between the coils according to the number of parallel branches.

[0070] The structural parameters of the original reference motor and the synchronous reluctance motor obtained by the optimized design are shown in Table 1.

[0071] Table 1

[0072]

[0073] The winding coefficients of the original equal-turn distributed winding and the winding coefficients of the unequal-turn concentric winding obtained by the optimized design are shown in Table 2;

[0074] Table 2

[0075] Harmonic Order Equal turns distributed winding Unequal turns concentric winding 1 0.9598 0.8979 3 0 0.3380 5 0.6667 0.0037 7 0 0.0282 9 0.2176 0 11 0 0.0282 13 0.1774 0.0037 15 0 0.3380 17 0.3333 0.8979

[0076] The results in Table 2 show that compared with the original equal-turn distributed winding, the optimized unequal-turn concentric winding produces a significantly reduced fifth harmonic content, thereby achieving a significant reduction in the torque pulsation of the motor.

[0077] At the same operating temperature, the performance of the reference motor and the optimized synchronous reluctance motor are simulated using finite element software, as shown in Table 3. Figure 6 and Figure 7 As shown;

[0078] Table 3

[0079]

[0080] Table 3 and Figure 6 , Figure 7 The performance comparison results show that based on the optimized design method of this embodiment, the torque pulsation of the motor is reduced from 12.91% to 4.71%, a decrease of 63.52%, and the efficiency is increased from 88.89% to 89.69%, an increase of 0.90%. This shows that the synchronous reluctance motor with unequal turns concentric windings and the design method thereof provided in this embodiment can slightly reduce the torque pulsation of the motor without affecting the average torque and output power of the motor, and can improve the efficiency of the motor.

[0081] In summary, compared with the prior art, the present application has the following advantages:

[0082] This application aims to modify the winding structure into a double-layer short-distance distributed concentric winding structure with unequal pitch and unequal turns under the coordination of various pole slots. For the purpose of reducing the low-order harmonics of the stator winding magnetomotive force, the initial number of turns configuration is calculated. Then, by adjusting the number of conductors per slot and the number of parallel branches, it is ensured that after the winding structure is modified, the current density, slot full rate and line load of the motor are respectively consistent with the reference motor, and then the final number of turns configuration is calculated. In addition, in order to improve the output torque of the motor, the stack length of the motor is increased while keeping the motor volume unchanged. In this way, it can be ensured that the harmonic content of the stator magnetomotive force and the harmonic content of the air gap magnetic density are effectively reduced without affecting the average torque and output power of the motor, thereby effectively reducing the rated torque pulsation of the motor and improving the efficiency of the motor; at the same time, in this optimization process, the design of the rotor structure is not involved, the design difficulty is small, and the design cost is low.

[0083] It should be understood that expressions such as “include” and “may include” used in the present application indicate the existence of disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements.

[0084] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense.

[0085] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for obtaining a synchronous reluctance motor with short-pitch unequal-turn concentric windings, characterized in that: Based on a variety of different pole slot settings, the winding structure of the motor is modified from a full-pitch or short-pitch equal-turn distributed winding to a short-pitch unequal-turn concentric winding structure, and a winding setting method for a synchronous reluctance motor is obtained; The method for obtaining the number of turns of a short-distance unequal-turn concentric winding specifically comprises the following steps: S1: Based on the current pole slot setting, use the slot number phase diagram to divide the phase band and select the pitch of each coil to draw the unit motor n Layer winding arrangement table; n ≥2; S2: Based on the unit motor n Layer winding arrangement table, keep the slot fill rate of each slot equal, with the goal of reducing the harmonic content and amplitude in the stator winding magnetomotive force, calculate the ratio of the number of turns of each coil in each coil group; S3: Adjust the number of conductors per slot and the number of parallel branches so that the current density, slot fill rate and line load of the motor before and after the modification remain consistent, and obtain the final turns configuration; When the motor is a double-layer 36-slot 4-pole motor, S2 specifically includes the following steps: Set the number of turns of the three coils from the inside to the outside in each coil group to be b , b + c , b + c + d ; According to the equal slot full rate of each slot, the number of turns of the three coils from the inside to the outside of each coil group is obtained as follows: b , b + c , b +2 c ; Convert non-equal-component windings into equal-component windings to obtain the winding coefficient of the unit motor; Calculated based on the winding coefficient of the unit motor with the goal of reducing the 5th, 7th, 11th and 13th stator harmonics c / b The value of is used to obtain the ratio of the number of turns of each coil in each coil group; Among them, when the motor is a double-layer 36-slot 4-pole motor, the winding coefficient of the unit motor is: in, is the harmonic order of the unit motor; =0, =0.

2. The method for obtaining a synchronous reluctance motor according to claim 1, characterized in that: The following steps are also included: The change in the extension length of the winding at the electrode end before and after adjusting the winding structure is calculated, and the motor stack length is increased while keeping the motor volume unchanged.

3. The method for obtaining a synchronous reluctance motor according to claim 1 or 2, characterized in that: The invention also includes a motor wire embedding method, which specifically includes the following steps: According to the unequal turns of the concentric winding, determine how many coils with different numbers of turns need to be wound; For each parallel branch, a coil with the same number of turns as the innermost coil is embedded in 2q slots; Coils are embedded in the other 2 (q-1) slots except the innermost layer, and the number of coil turns is the difference between the number of turns of the second coil from the inner layer to the outside and the number of turns of the innermost coil; The coils are embedded in the slots except the innermost and second innermost slots, and the number of coil turns is the difference between the number of turns of the third coil from the inner layer to the outside and the number of turns of the second coil; And so on, finally determine the connection method between coils according to the number of parallel branches; Where q is the number of slots per pole per phase.

4. A synchronous reluctance motor with short-pitch unequal-turn concentric windings, characterized in that: include: The rotating shaft, the rotor core and the stator core are arranged in sequence from the inside to the outside; the rotor core is provided with a rotor magnetic barrier, and the stator core is provided with a winding; The structure of the winding is modified from a full-pitch or short-pitch equal-turn distributed winding to a short-pitch unequal-turn concentric winding structure; the number of turns of the winding is the final number of turns obtained in claim 1; the connection method of the winding is determined according to the number of parallel branches.

5. The synchronous reluctance motor according to claim 4, characterized in that: The motor wire embedding is performed according to the motor wire embedding method of claim 3.

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