Pole-changing single-phase induction motor

Abstract

The utility model 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] This utility model relates to the field of motor technology, and in particular to a pole-changing single-phase induction motor. Background Technology

[0002] In existing variable-pole speed-regulating induction motors, the rotor structure remains unchanged. To enable the compressor to adapt to new loads under different operating conditions (indoor and outdoor temperatures, heat exchange conditions), the number of poles is changed by switching the circuit connected to the stator on the outside of the rotor. This allows the motor to switch between a 2-pole induction motor and a 4-pole induction motor. However, such motors capable of switching poles exhibit high third harmonics during operation. Since the motor itself has a fundamental torque, the final output torque is the superposition of the fundamental torque and the third harmonic. Because the torque output of the third harmonic is unstable as the speed increases, the final torque output of the motor is unstable, ultimately preventing the motor from starting normally. At the same time, regardless of whether the motor is operating in 2-pole or 4-pole mode, its winding coefficient is low, which reduces the effective number of turns and ultimately leads to a decrease in motor efficiency. Utility Model Content

[0003] The purpose of this invention is to provide a variable-pole single-phase induction motor that solves the problems of low motor efficiency and inability to start normally under existing technology.

[0004] To achieve this objective, the present invention adopts the following technical solution: The present invention provides a pole-changing single-phase induction motor, including a stator and a rotor. An annular cavity is formed inside the stator, and a plug-in slot is formed on the inner wall of the annular cavity. 3N sets of plug-in slots are circumferentially arranged. N sets of coil assemblies are installed in the plug-in slots. Each coil assembly includes a first coil, a second coil, and a third coil. Each set of plug-in slots contains two sets of coils. The span of the first coil is N+2, the span of the second coil is N, and the span of the third coil is N-2, where N is a positive integer.

[0005] Preferably, the insertion slot has 24 sets, and 8 sets of coil assemblies are installed in the insertion slot.

[0006] Preferably, four sets of mounting layers are formed along the radial direction of the stator, and two sets of coil assemblies are installed in each set of mounting layers. A set of mounting slots is spaced between the two ends of the coil assembly in the mounting layer and the two ends of the coil assembly in the other set.

[0007] Preferably, the insertion slots are numbered from slot 1 to slot 24 in a clockwise direction. A first coil is inserted into slot 1, a second coil is inserted into slot 2, and a third coil is inserted into slot 3. A common terminal is connected to one group of the first coils, and the first coil with the common terminal is marked as terminal 1. All the first coils and the third coils are numbered sequentially from terminal 1 to terminal 16 in a clockwise direction.

[0008] Preferably, when the variable-pole single-phase induction motor is in 2-pole mode, the common terminal is simultaneously connected to the first terminal, the 16th terminal, the 4th terminal and the 5th terminal; 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 variable-pole single-phase induction motor is in 4-pole mode, the common terminal is connected to both the first and third terminals, the sixth terminal is connected to the ninth terminal, the fourteenth terminal is connected to the second terminal, the thirteenth terminal is connected to the tenth terminal, the fifth terminal is connected to the main output terminal, the eighth terminal is connected to the eleventh terminal, the sixteenth terminal is connected to the twelfth terminal, the seventh terminal is connected to the fourth terminal, and the fifteenth 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 the capacitor.

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

[0012] Preferably, the operating capacitance value in the 4-pole mode is Cr2, 0.3*Cr1. <Cr2≤Cr1。

[0013] Beneficial effects: N sets of coil assemblies are arranged in the insertion slots inside the stator. The first, second, and third coils within each coil assembly have spans of N+2, N, and N-2 respectively within the insertion slot. This ensures that each insertion slot contains two sets of coils. Through this winding method, the coils are brought closer to the magnetic pole center, resulting in a higher back electromotive force and thus a higher winding coefficient. In this invention, each insertion slot contains two sets of coils, allowing the coil assembly to be closer to the average distance of the motor's magnetic pole center. Simultaneously, the coil assembly makes the distribution of the air gap magnetomotive force approximate a sine wave. According to the laws of physics, when the third harmonic is close to a sine wave, its influence on the electrodes is minimized, making the motor's operating state more stable. It also allows for compatibility with 2-pole and 4-pole operating states, enabling the variable-pole single-phase induction motor to achieve a higher winding coefficient, thereby improving the motor's efficiency. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view of the variable pole single-phase induction motor of this utility model;

[0015] Figure 2 This is the wiring diagram for the 2-pole mode motor of this utility model;

[0016] Figure 3 This is the wiring diagram for the 4-pole mode motor of this utility model.

[0017] In the diagram: 1. Terminal 1; 2. Terminal 2; 3. Terminal 3; 4. Terminal 4; 5. Terminal 5; 6. Terminal 6; 7. Terminal 7; 8. Terminal 8; 9. Terminal 9; 10. Terminal 10; 11. Terminal 11; 12. Terminal 12; 13. Terminal 13; 14. Terminal 14; 15. Terminal 15; 16. Terminal 16; 17. Stator; 171. Connecting slot; 18. First coil; 19. Second coil; 20. Third coil. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0019] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0020] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0021] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0022] Pole-changing speed-regulating induction motors need to adapt to different working environments. They can change poles by switching the coils connected in the stator slots, allowing the motor to switch between 2-pole and 4-pole induction motor modes. However, with current technology, the motor generates a high third harmonic, which leads to unstable motor output and failure 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, resulting in lower motor efficiency.

[0023] To solve the above problems, such as Figures 1 to 3As shown, this utility model provides a pole-changing single-phase induction motor, including a stator 17 and a rotor. An annular cavity is formed within the stator 17, and insertion slots 171 are formed on the inner wall of the annular cavity. 3N groups of insertion slots 171 are circumferentially arranged, and N groups of coil assemblies are installed within each insertion slot 171. Each coil assembly includes a first coil 18, a second coil 19, and a third coil 20. Each insertion slot 171 accommodates two 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 insertion slot 171 twice. The total length of the insertion slot 171 between each coil is the span.

[0024] Since 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, the first coil 18 is on the outermost side, the second coil 19 is in the middle, and the third coil 20 is on the innermost side within the coil assembly. Through this arrangement, each slot can accommodate two different sets of coils, making the total distribution of the coils closer to the center of the magnetic pole. This allows the pole-changing single-phase induction motor to have a higher back electromotive force, thereby increasing the winding coefficient and ultimately improving the efficiency of the motor.

[0025] Specifically, in the 2-pole state, the improved winding coefficient increases from 0.691 to 0.792, while in the 4-pole state, the improved winding coefficient increases from 0.667 to 0.788. Since the improved winding slot has two layers of coils, 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] In this invention, the N value in the variable-pole single-phase induction motor is equal to 8. By changing different N values, the winding method described above can be used in motors of different specifications to make the winding distribution within the motor closer to a sine wave. This allows motors of different specifications to reduce the third harmonic and improve motor efficiency.

[0027] The stator 17 of this utility model has 24 sets of insertion slots 171 on its inner wall, and a total of 8 sets of coil assemblies are provided. The spans of the first coil 18 to the third coil 20 are 10, 8 and 6 respectively. By setting 2 sets of coils, the coil assemblies can be closer to the center of the magnetic pole, thereby improving the efficiency of the motor.

[0028] Four sets of mounting layers are formed radially along the stator 17. Each set of mounting layers contains two sets of coil assemblies. Each end of a coil assembly in a mounting layer is separated from the ends of another set of coil assemblies by a set of mounting slots. Through this arrangement, each set of mounting slots can contain two sets of coils, 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. This brings the coil assemblies closer to the magnetic pole center, improving motor performance and reducing heat generation. At the same time, the distribution law of the air gap magnetomotive force of the motor in this invention is close to a sine wave, which can suppress the occurrence of the third harmonic. Through the coil arrangement of this patent, the third harmonic can be eliminated, allowing the motor to start based on the fundamental torque, eliminating the instability of the third harmonic, and enabling the motor to start normally under any circumstances.

[0029] In a clockwise direction, slots 171 are numbered from slot 1 to slot 24. Slot 1 houses a first coil 18, slot 2 houses a second coil 19, and slot 3 houses a third coil 20. One set of first coils 18 has a common terminal externally connected to it, and this first coil 18 with the common terminal is marked as terminal 1. In a clockwise direction, all the first coils 18 and third coils 20 appearing in sequence are numbered as terminal 1 to terminal 16, with each coil marked only once. With 16 sets of terminals, a common terminal, a secondary output terminal, and a main output terminal can be externally connected at different positions. By changing the connection state of different circuits, the variable-pole single-phase induction motor can switch between 2-pole and 4-pole modes. The efficiency of this motor is 87% in 2-pole mode and 74.2% in 4-pole mode.

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

[0031] At this time, the single-phase induction motor with pole changing is in the 2-pole state. Since the distribution law of the motor air gap magnetomotive force is close to sinusoidal, the third harmonic can be weakened or eliminated, and the waveform of the motor air gap magnetomotive force can be improved, thereby improving motor efficiency, improving starting performance and reducing 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 capacitor 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 capacitor value in the 4-pole mode is Cr2, 0.3 * Cr1 < Cr2 ≤ Cr1. By adjusting the size of the running capacitor, 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 merely examples for clearly explaining the present invention, rather than 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 within the protection scope of the claims of the present invention.

Claims

1. A variable pole single phase induction motor characterized by, The variable-pole single-phase induction motor comprises a stator (17) and a rotor, an annular cavity is formed in the stator (17), an insertion slot (171) is formed on the inner wall of the annular cavity, 3N groups of insertion slots (171) are circumferentially arranged, N groups of coil assemblies are arranged in the insertion slots (171), the coil assembly comprises a first coil (18), a second coil (19) and a third coil (20), two groups of coils are arranged in each group of insertion slots (171), 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, and N is a positive integer.

2. The variable pole single-phase induction motor according to claim 1, characterized in that, The insertion slot (171) is provided with 24 groups, and 8 groups of coil assemblies are arranged in the insertion slot (171).

3. The variable pole single-phase induction motor according to claim 2, characterized in that, Four groups of mounting layers are formed along the radial direction of the stator (17), two groups of coil assemblies are arranged in each mounting layer, and the two ends of the coil assembly in the mounting layer are spaced apart from the two ends of another coil assembly by a mounting slot.

4. The variable pole single-phase induction motor according to claim 3, characterized in that, In the clockwise direction, the insertion slots (171) are numbered as the first slot to the twenty-fourth slot, the first coil (18) is inserted into the first slot, the second coil (19) is inserted into the second slot, and the third coil (20) is inserted into the third slot; one group of the first coil (18) is circumscribed with a common end, the first coil (18) circumscribed with the common end is marked as the first wiring end (1), and in the clockwise direction, all the first coils (18) and the third coils (20) are sequentially numbered as the first wiring end (1) to the sixteenth wiring end (16).

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

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

7. The variable pole single-phase induction motor according to claim 6, characterized in that, The common end, the auxiliary outgoing line end and the main outgoing line end are electrically connected to a capacitor.

8. The variable pole single-phase induction motor according to claim 7, characterized in that, The operating capacitance value in the 2-pole mode is Cr1, and 0.3Cr1≤Cr1.

9. The variable pole single-phase induction motor according to claim 8, characterized in that, The operating capacitance value in the 4-pole mode is Cr2, and 0.3*Cr1<Cr2≤Cr1.

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