Pole-changing single-phase induction motor

Abstract

The invention belongs to the technical field of motors, and discloses a pole-changing single-phase induction motor. The motor comprises a stator and a rotor, an annular cavity is formed in the stator, inserting grooves are formed in the inner wall of the annular cavity, 3N groups of coil assemblies are formed in the circumferential direction of the inserting grooves, N groups of coil assemblies are installed in the inserting grooves, each coil assembly comprises a first coil, a second coil and a third coil, two groups of coils are contained in each group of inserting grooves, the span of the first coil is N + 2, and the span of the second coil is N, the span of the third coil is N-2; the problems that in the prior art, motor efficiency is low, and a motor cannot be normally started are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a pole-changing single-phase induction motor. Background Art

[0002] The rotor structure of the variable-pole speed-regulating induction motor under the prior art remains unchanged. In order to enable the compressor to adapt to new loads under different working conditions (indoor and outdoor temperatures, heat exchange conditions), the circuit connected to the stator outside the rotor is turned on and off to change the number of stages, so that the motor can be switched between a 2-pole induction motor and a 4-pole induction motor. However, during use, such motors that can switch the number of stages will have a higher third harmonic. Since the motor itself has a fundamental torque, the final output motor torque is the superposition of the fundamental torque and the third harmonic. Since the third harmonic itself has an unstable torque output as the speed increases, the final torque output of the motor is unstable, which ultimately causes the motor to fail to start normally. At the same time, whether this type of motor is in a 2-pole working state or a 4-pole working state, its winding coefficient is low, which will reduce the effective number of turns of the motor, and ultimately lead to the problem of reduced motor efficiency. Summary of the invention

[0003] The object of the present invention is to provide a pole-changing single-phase induction motor to solve the problem that the motor efficiency is low and the motor cannot be started normally in the prior art.

[0004] To achieve this object, the present invention adopts the following technical scheme: The present invention provides a pole-changing single-phase induction motor, including a stator and a rotor, an annular cavity is formed in the stator, and the inner wall of the annular cavity is formed with plug-in slots, and 3N groups of plug-in slots are opened in the circumference, and N groups of coil assemblies are installed in the plug-in slots, and the coil assemblies include a first coil, a second coil and a third coil. Each group of plug-in slots accommodates two groups of coils, the first coil span is N+2, the second coil span is N, and the third coil span is N-2, and N is a positive integer.

[0005] Preferably, 24 groups of the plug-in slots are provided, and 8 groups of coil assemblies are installed in the plug-in slots.

[0006] Preferably, four groups of installation layers are formed along the radial direction of the stator, two groups of coil assemblies are installed in each group of the installation layers, and two ends of the coil assemblies in the installation layer are separated from two ends of another group of coil assemblies by a group of installation grooves.

[0007] Preferably, the plug-in slots are numbered from the 1st slot to the 24th slot in the clockwise direction, the first coil is plugged into the 1st slot, the second coil is plugged into the 2nd slot, and the third coil is plugged into the 3rd slot; one group of the first coils is externally connected to a common terminal, and the first coil externally connected to the common terminal is marked as the 1st terminal, and all the first coils and the third coils are numbered from the 1st terminal to the 16th terminal in the clockwise direction.

[0008] Preferably, when the pole-changing single-phase induction motor is in 2-pole mode, the common terminal is connected to the 1st terminal, the 16th terminal, the 4th terminal and the 5th terminal at the same time, the 6th terminal is connected to the 3rd terminal, the 11th terminal is connected to the 14th terminal, the 15th terminal is connected to the 2nd terminal, the 10th terminal is connected to the 7th terminal, the 8th terminal and the 9th terminal are connected to the main output terminal, and the 13th terminal and the 12th terminal are connected to the auxiliary output terminal.

[0009] Preferably, when the pole-changing single-phase induction motor is in a 4-pole mode, the common terminal is connected to the 1st terminal and the 3rd terminal at the same time, the 6th terminal is connected to the 9th terminal, the 14th terminal is connected to the 2nd terminal, the 13th terminal is connected to the 10th terminal, the 5th terminal is connected to the main output terminal, the 8th terminal is connected to the 11th terminal, the 16th terminal is connected to the 12th terminal, the 7th terminal is connected to the 4th terminal, and the 15th terminal is connected to the auxiliary output terminal.

[0010] Preferably, the common terminal, the secondary output terminal and the main output terminal are all electrically connected to a capacitor.

[0011] Preferably, the operating capacitance value in the 2-pole mode is Cr1, 0.3Cr1≤Cr1.

[0012] As a preferred embodiment, the operating capacitor value in the 4-pole mode is Cr2, 0.3*Cr1 <Cr2≤Cr1。

[0013] Beneficial effect: N groups of coil assemblies are arranged in the plug-in slots inside the stator, including the first coil, the second coil and the third coil inside the coil assembly, and the spans of each coil inside the plug-in slot are N+2, N, and N-2 respectively, so that the number of coils in each plug-in slot can be maintained at two groups. Through the above-mentioned winding method, the coil is closer to the center of the magnetic pole, so that the motor has a higher back electromotive force, and thus a higher winding coefficient is obtained. In the present invention, two groups of coils are accommodated in each group of plug-in slots, so that the coil assembly can be closer to the average distance from the center of the motor magnetic pole. At the same time, the above-mentioned coil assembly can make the distribution law of the air gap magnetic potential close to a sine shape. According to the laws of physics, when the third harmonic is close to a sine wave, the influence of the third harmonic on the electrode is minimized, so that the working state of the motor is more stable. At the same time, it can be compatible with the working state of the motor under 2 poles and 4 poles, so that the pole-changing single-phase induction motor can obtain a higher winding coefficient, thereby improving the efficiency of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a cross-sectional view of a pole-changing single-phase induction motor of the present invention;

[0015] Figure 2 It is the wiring diagram of the 2-pole mode motor of the present invention;

[0016] Figure 3 This is the wiring diagram of the 4-pole mode motor of the present invention.

[0017] In the figure: 1, the first terminal; 2, the second terminal; 3, the third terminal; 4, the fourth terminal; 5, the fifth terminal; 6, the sixth terminal; 7, the seventh terminal; 8, the eighth terminal; 9, the ninth terminal; 10, the tenth terminal; 11, the eleventh terminal; 12, the twelfth terminal; 13, the thirteenth terminal; 14, the fourteenth terminal; 15, the fifteenth terminal; 16, the sixteenth terminal; 17, the stator; 171, the plug-in slot; 18, the first coil; 19, the second coil; 20, the third coil. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0019] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0021] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0022] The pole-changing speed-regulating induction motor needs to adapt to different working environments. The poles can be changed by switching the coils connected in the stator slots, so that the motor can be switched between a 2-pole induction motor and a 4-pole induction motor. However, under current technology, the motor will generate higher third harmonics, which will cause the motor's own output to be unstable and unable to start normally. At the same time, in order to adapt to the pole-changing working state, the effective number of turns of the motor is reduced, and the efficiency of the motor itself will also be lower.

[0023] In order to solve the above problems, Figures 1 to 3As shown, the present invention provides a pole-changing single-phase induction motor, which includes a stator 17 and a rotor. An annular cavity is formed in the stator 17. The inner wall of the annular cavity is formed with a plug-in slot 171. The plug-in slot 171 is provided with 3N groups in the circumferential direction. N groups of coil assemblies are installed in the plug-in slot 171. The coil assembly includes a first coil 18, a second coil 19 and a third coil 20. Each group of plug-in slots 171 contains two groups of coils. The span of the first coil 18 is N+2, the span of the second coil 19 is N, and the span of the third coil 20 is N-2, where N is a positive integer. Both ends of each coil need to be inserted into the plug-in slot 171 twice, and the plug-in slots 171 accommodated between each coil are the span.

[0024] Since the span of the first coil 18 is N+2, the span of the second coil 19 is N, and the span of the third coil 20 is N-2, at this time, in the coil assembly, the first coil 18 is at the outermost side, the second coil 19 is in the middle, and the third coil 20 is at the innermost side. Through the above arrangement, two groups of different coils can be accommodated in each slot, so that the total distribution of the coil is closer to the center of the magnetic pole, thereby making the pole-changing single-phase induction motor have a higher back electromotive force, thereby improving the winding coefficient, and ultimately improving the efficiency of the motor.

[0025] Specifically, in the 2-pole state, the improved winding coefficient is increased from 0.691 to 0.792. At the same time, in the 4-pole state, the improved winding coefficient is upgraded from 0.667 to 0.788. Since two layers of coils are arranged in the improved wire slot, the average distance between the coil and the center of the magnetic pole is closer, which can increase the winding coefficient of the motor, thereby improving the motor efficiency and reducing the heat generated by the motor.

[0026] N in the pole-changing single-phase induction motor of the present invention is equal to 8. At the same time, by changing different N values ​​and using the above-mentioned winding method in motors of different specifications, the winding distribution inside the motor can be made closer to a sine wave, thereby enabling motors of different specifications to reduce the third harmonic and improve the efficiency of the motor.

[0027] The inner wall of the stator 17 of the pole-changing speed-regulating induction motor of the present invention is provided with 24 groups of plug-in slots 171, and a total of 8 groups of coil assemblies are provided. The spans from the first coil 18 to the third coil 20 are 10, 8, and 6 respectively. By providing 2 groups of coils, the coil assembly can be closer to the center of the magnetic pole, thereby improving the efficiency of the motor.

[0028] Four groups of mounting layers are formed along the radial direction of the stator 17, and two groups of coil assemblies are installed in each mounting layer. A group of mounting grooves are separated at both ends of the coil assembly in the mounting layer from both ends of the other group of coil assemblies. Through the above arrangement, two groups of coils can be installed in each group of mounting grooves, which can be the first coil 18 and the second coil 19 or the first coil 18 and the third coil 20 or the second coil 19 and the third coil 20, so that the coil assembly is closer to the center of the magnetic pole, the performance of the motor is improved, the heat generation is reduced, and at the same time, the distribution law of the air gap magnetic potential of the motor of the present invention can be close to the sine shape, so that the occurrence of the third harmonic can be suppressed. Through the coil arrangement of this patent, the third harmonic can be eliminated, so that the motor can be started by relying on the fundamental torque, the instability of the third harmonic is eliminated, and the motor can be started normally under any circumstances.

[0029] In the clockwise direction, the numbered slots 171 are slots 1 to 24, the first slot is plugged with the first coil 18, the second slot is plugged with the second coil 19, and the third slot is plugged with the third coil 20; one group of first coils 18 is externally connected to a common terminal, and the first coil 18 externally connected to the common terminal is marked as the first terminal 1, and in the clockwise direction, all the first coils 18 and third coils 20 that appear in sequence are numbered as the first terminal 1 to the 16th terminal 16, and each coil can be marked only once. 16 groups of terminals are provided, and the common terminal, the auxiliary output terminal and the main output terminal can be externally connected at different positions. By changing the connection state of different circuits, the pole-changing single-phase induction motor can be switched between the 2-pole mode and the 4-pole mode. The efficiency of the motor of the present invention is 87% in the 2-pole mode and 74.2% in the 4-pole mode.

[0030] When the pole-changing single-phase induction motor is in 2-pole mode, the common terminal is simultaneously connected to the 1st terminal 1, the 16th terminal 16, the 4th terminal 4 and the 5th terminal 5, the 6th terminal 6 is connected to the 3rd terminal 3, the 11th terminal 11 is connected to the 14th terminal 14, the 15th terminal 15 is connected to the 2nd terminal 2, the 10th terminal 10 is connected to the 7th terminal 7, the 8th terminal 8 is connected to the 9th terminal 9 to the main output terminal, and the 13th terminal 13 and the 12th terminal 12 are connected to the auxiliary output terminal.

[0031] At this time, the pole-changing single-phase induction motor is in a 2-pole state. Since the distribution law of the motor air gap magnetic potential is close to a sine shape, the third harmonic can be weakened or eliminated, and the motor air gap magnetic potential waveform can be improved, thereby improving the motor efficiency, improving the starting performance, and reducing the motor temperature rise.

[0032] When the pole-changing single-phase induction motor is in the 4-pole mode, the common terminal is connected to the first terminal 1 and the third terminal 3 at the same time. The sixth terminal 6 is connected to the ninth terminal 9, the fourteenth terminal 14 is connected to the second terminal 2, the thirteenth terminal 13 is connected to the tenth terminal 10, the fifth terminal 5 is connected to the main outgoing line terminal, the eighth terminal 8 is connected to the eleventh terminal 11, the sixteenth terminal 16 is connected to the twelfth terminal 12, the seventh terminal 7 is connected to the fourth terminal 4, and the fifteenth terminal 15 is connected to the auxiliary outgoing line terminal. At this time, the motor is in the 4-pole state. Since the air-gap distribution of the motor at this time is a positive selection type, the third harmonic can be reduced, and thus the working efficiency of the motor can be improved.

[0033] When the common terminal, the auxiliary outgoing line terminal and the main outgoing line terminal are all electrically connected to the capacitor, it can help the motor start smoothly, improve the success rate of motor starting, and at the same time reduce the electromagnetic interference generated during the operation of the motor, making the waveform smoother.

[0034] It should be particularly noted that the running capacitance value of the pole-changing single-phase induction motor of the present invention in the 2-pole mode is Cr1, 0.3Cr1 ≤ Cr1, and the running capacitance value in the 4-pole mode is Cr2, 0.3*Cr1 < Cr2 ≤ Cr1. By adjusting the size of the running capacitance, the starting torque can be appropriately increased, but the values of Cr1 and Cr2 cannot be too large to reduce the risk of the motor overheating or being burned out.

[0035] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A pole-changing single-phase induction motor, characterized in that: The invention comprises a stator (17) and a rotor, wherein an annular cavity is formed in the stator (17), and the inner wall of the annular cavity is formed with plug-in slots (171), and 3N groups of the plug-in slots (171) are opened in the circumferential direction, and N groups of coil assemblies are installed in the plug-in slots (171), and the coil assemblies include a first coil (18), a second coil (19) and a third coil (20), and each group of plug-in slots (171) contains two groups of coils, the first coil (18) has a span of N+2, the second coil (19) has a span of N, and the third coil (20) has a span of N-2, where N is a positive integer.

2. The pole-changing single-phase induction motor according to claim 1, characterized in that: The plug-in slots (171) are provided with 24 groups, and 8 groups of coil assemblies are installed in the plug-in slots (171).

3. The pole-changing single-phase induction motor according to claim 2, characterized in that: Four groups of installation layers are formed radially along the stator (17), two groups of coil assemblies are installed in each group of the installation layers, and a group of installation grooves are spaced between the two ends of the coil assemblies in the installation layer and the two ends of the coil assemblies in another group.

4. The pole-changing single-phase induction motor according to claim 3, characterized in that: In the clockwise direction, the plug-in slots (171) are numbered from the 1st slot to the 24th slot, the 1st slot is plugged with the first coil (18), the 2nd slot is plugged with the second coil (19), and the 3rd slot is plugged with the third coil (20); one group of the first coils (18) is externally connected to a common terminal, and the first coil (18) externally connected to the common terminal is marked as the 1st terminal (1), and in the clockwise direction, all the first coils (18) and the third coils (20) are numbered from the 1st terminal (1) to the 16th terminal (16) in sequence.

5. The pole-changing single-phase induction motor according to claim 4, characterized in that: When the pole-changing single-phase induction motor is in a two-pole mode, the common terminal is simultaneously connected to the first terminal (1), the sixteenth terminal (16), the fourth terminal (4) and the fifth terminal (5), the sixth terminal (6) is connected to the third terminal (3), the eleventh terminal (11) is connected to the fourteenth terminal (14), the fifteenth terminal (15) is connected to the second terminal (2), the tenth terminal (10) is connected to the seventh terminal (7), the eighth terminal (8) is connected to the ninth terminal (9) as a main output terminal, and the thirteenth terminal (13) is connected to the twelfth terminal (12) as a secondary output terminal.

6. The pole-changing single-phase induction motor according to claim 5, characterized in that: When the pole-changing single-phase induction motor is in a 4-pole mode, the common terminal is simultaneously connected to the first terminal (1) and the third terminal (3), the sixth terminal (6) is connected to the ninth terminal (9), the fourteenth terminal (14) is connected to the second terminal (2), the thirteenth terminal (13) is connected to the tenth terminal (10), the fifth terminal (5) is connected to the main output terminal, the eighth terminal (8) is connected to the eleventh terminal (11), the sixteenth terminal (16) is connected to the twelfth terminal (12), the seventh terminal (7) is connected to the fourth terminal (4), and the fifteenth terminal (15) is connected to the auxiliary output terminal.

7. The pole-changing single-phase induction motor according to claim 6, characterized in that: The common terminal, the secondary output terminal and the main output terminal are all electrically connected to the capacitor.

8. The pole-changing single-phase induction motor according to claim 7, characterized in that: The operating capacitor value in 2-pole mode is Cr1, 0.3Cr1≤Cr1.

9. The pole-changing single-phase induction motor according to claim 8, characterized in that: The operating capacitor value in 4-pole mode is Cr2, 0.3*Cr1 <Cr2≤Cr1。

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