KR102629498B1 - Single-phase induction motor - Google Patents

Abstract

This specification relates to single phase induction motors. A single-phase induction motor according to an embodiment of this specification includes a stator and a rotor provided with a plurality of slots, and the plurality of slots include small slots, medium slots, large slots, large slots, large slots, large slots, and medium slots. , and a first to fourth unit slot section with the first to eighth slots in the minor slot order as the unit slot section, and the main winding is composed of the second to fourth unit slot sections in the first unit slot section and the third unit slot section. 7 slots in the first direction, and pass through the 2nd to 7th slots in the 2nd unit slot section and the 4th unit slot section in the 2nd direction opposite to the first direction, and the auxiliary winding is in the 1st unit slot. In the section and the third unit slot section, the first to third slots are passed in the first direction and the sixth to eighth slots are passed in the second direction, and in the second unit slot section and the fourth unit slot section, the first to third slots are passed in the first direction. passing through the third slot in the second direction and passing through the sixth to eighth slots in the first direction, the number ratios of the main winding passing through the second, third and fourth slots are 0.263, 0.346 and 0.391, and the auxiliary winding passes through the second, third and fourth slots. The turn ratio at which the winding passes through the first, second and third slots may be 0.440, 0.300 and 0.260.

Description

Single-phase induction motor {Single-phase induction motor}

This specification relates to single-phase induction motors, and more specifically to the turns ratio of the main coil and auxiliary coil wound on the stator of a single-phase induction motor.

In a single-phase induction motor, the main coil and the auxiliary coil are wound on the stator (or stator) at a spatial 90 degree deviation from each other, and the single-phase AC power is applied directly to the main coil, and the auxiliary coil connected in parallel is supplied with AC through a capacitor and switch. Turn on the power.

Due to the capacitor, the current flowing in the auxiliary coil flows ahead of the current flowing in the main coil by a phase difference of 90 degrees, that is, it operates like a two-phase inductor and forms a rotating magnetic field that allows the rotor (or rotor) to rotate. .

When a single-phase induction motor reaches a predetermined speed, for example, about 75% to 80% of the rated speed, the centrifugal force switch operates to open the connection with the auxiliary coil, so that only the main coil operates. When operating in single phase, not only the fundamental torque but also all harmonic torques are generated, which reduces the average torque of the single-phase induction motor and can cause vibration and noise due to torque pulsation.

To reduce harmonics of single-phase induction motors, a skew angle is generally applied to the rotor conductor bars. Increasing the skew angle is advantageous in reducing harmonics, but there is a problem in that performance deteriorates and material costs increase due to an increase in the resistance of the rotor conductor bar.

(Prior Art 1) Korean Patent Publication 10-2007-0113192 (published on November 28, 2007) (Prior Art 1) Korean Patent Publication 10-2006-0000183 (published on January 6, 2006)

This specification takes this situation into consideration, and the purpose of this specification is to provide a single-phase induction motor that reduces the harmonic components contained in the magnetomotive force generated by the main coil and auxiliary coil.

A single-phase induction motor according to an embodiment of this specification for realizing the above-described problem includes a core and a stator including a main winding and an auxiliary winding passing through a plurality of slots provided in the core, and a stator that rotates by mutual electromagnetic force with the stator. In a single-phase induction motor including a rotor, when a plurality of slots are classified into small slots, medium slots, and large slots based on the depth in the radial direction, the plurality of slots are small slots, medium slots, large slots, and large slots. , It is composed of first to fourth unit slot sections with the first to eighth slots in the order of large slots, large slots, medium slots, and small slots as unit slot sections, and the main winding is comprised of the first unit slot section and the first unit slot section. Passing through the 2nd to 7th slots in the first direction in the 3 unit slot section, passing through the 2nd to 7th slots in the 2nd to 7th slots in the 2nd unit slot section and the 4th unit slot section in the second direction opposite to the first direction, , the auxiliary winding passes through the first to third slots in the first direction and the sixth to eighth slots in the second direction in the first unit slot section and the third unit slot section, and passes through the second unit slot section and In the fourth unit slot section, the 1st to 3rd slots are passed in the second direction, the 6th to 8th slots are passed in the first direction, and the main winding passes through the 2nd, 3rd, and 4th slots. is 0.263, 0.346, and 0.391, and the recovery ratio of the auxiliary winding passing through the first, second, and third slots is 0.440, 0.300, and 0.260.

Therefore, by adjusting the turns ratio of the main coil and the auxiliary coil, the harmonic component included in the winding magnetomotive force can be minimized.

Additionally, when starting the rotor, the crawling phenomenon caused by harmonic torque pulsation of the main coil and auxiliary coil can be avoided.

Additionally, by reducing harmonic torque, motor dynamic characteristics can be improved by improving starting torque and rated torque.

Additionally, the skew angle of the rotor conductor bar can be minimized, thereby suppressing increases in rotor resistance and material costs.

Additionally, by improving harmonic torque pulsation, torque ripple, vibration and noise characteristics can be improved during rated operation.

Figure 1 shows a cross section of a single-phase induction motor,
Figure 2 shows a circuit diagram of a single-phase induction motor that generates a rotating magnetic field that rotates the rotor by connecting an auxiliary coil with a capacitor connected in series in parallel with the main coil,
Figure 3 shows a slot formed in a stator constituting a single-phase induction motor according to an embodiment of this specification;
Figure 4 shows the arrangement of the main coil and the auxiliary coil wound around the slot of the stator of a single-phase induction motor according to an embodiment of this specification;
Figure 5 is a table showing the slots through which the main coil and the auxiliary coil pass and the directions through the slots.
Figure 6 is a table showing the winding ratio of the main coil and the auxiliary coil for canceling harmonics according to an embodiment of this specification,
Figure 7 is a graphical representation of the magnetomotive force distribution of the main coil;
Figure 8 is a graph showing the frequency characteristics of the magnetomotive force of the main coil,
Figure 9 is a graphical representation of the magnetomotive force distribution of the auxiliary coil.
Figure 10 is a graph showing the frequency characteristics of the magnetomotive force of the auxiliary coil.
Figure 11 is a graph showing the speed and torque characteristics when starting the rotor;
Figure 12 is a graph showing speed and torque characteristics when the rotor is operated at rated speed.

Hereinafter, embodiments disclosed in the present disclosure will be described in detail with reference to the attached drawings, but identical or similar components will be assigned the same reference numbers regardless of the reference numerals, and duplicate descriptions thereof will be omitted.

In describing the embodiments disclosed herein, when a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component. It should be understood that other components may exist in the middle.

Additionally, in describing the embodiments disclosed in this specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed descriptions will be omitted. In addition, the attached drawings are only for easy understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the attached drawings, and all changes included in the spirit and technical scope of this specification are not limited. , should be understood to include equivalents or substitutes.

Meanwhile, the term disclosure can be replaced with terms such as document, specification, and description.

Figure 1 shows a cross-section of a single-phase induction motor, and Figure 2 shows a circuit diagram of a single-phase induction motor that generates a rotating magnetic field that rotates the rotor by connecting an auxiliary coil with a capacitor connected in series in parallel with the main coil.

The single-phase induction motor (1) consists of a stator (10) corresponding to the stator and a rotor (20) corresponding to the rotor.

In the stator 10, a plurality of slots 110 are arranged along the circumference of the stator iron core 100, which is formed by stacking steel plates. The main coil 121 and the auxiliary coil 122 pass through the plurality of slots 110.

The rotor 20 includes a rotor iron core 200 formed by stacking steel plates in a round shape, a rod-shaped conductor bar 220 formed on the outer circumference of the rotor iron core 200, and the center of the rotor iron core 200. It may include an axial hole 220 formed in .

The conductor bar 220 can be made of copper or aluminum rod. When power is applied to the main coil 121 and the auxiliary coil 122, an induced current is generated in the conductor bar 220, and the rotor 20 rotates by the induced torque generated through this.

A rotation shaft (not shown) that transmits the rotation force of the rotor 20 to the outside is press-fitted into the shaft hole 220, so that the rotor 20 and the rotation shaft rotate as one body.

The main coil 121 and the auxiliary coil 122 are wound in the slots 110 of the stator 10 at a spatial interval of 90 degrees.

Single-phase AC power is applied to the main coil 121. A capacitor may be connected in series to the auxiliary coil 122, and the auxiliary coil 122 and the capacitor connected in series may be connected in parallel to the main coil 121.

Since the capacitor is connected in series to the auxiliary coil 122, a current whose phase is faster than the voltage flows through the auxiliary coil 122, and thus the main coil 121 and the auxiliary coil 122 have a phase difference of 90 degrees. Rotational magnetomotive force is generated by the main coil 121 and the auxiliary coil 122 having a phase difference of 90 degrees to rotate the rotor 20.

In addition, a switch is also connected in series to the auxiliary coil 122, and the switch is operated by centrifugal force when the rotor 20 exceeds a predetermined speed to separate the auxiliary coil 122 from the main coil 121.

Figure 3 shows a slot formed in a stator constituting a single-phase induction motor according to an embodiment of this specification, and Figure 4 shows a main coil wound around the slot of the stator of a single-phase induction motor according to an embodiment of this specification. It shows the arrangement of the main coil and the auxiliary coil, and Figure 5 shows a table showing the slots through which the main coil and the auxiliary coil pass and the direction through which the slots pass.

Figure 3 shows the stator 10 cut in quarters. Since 8 slots 110 are formed in Figure 3, the stator 10 has a total of 32 slots around the circumference as shown in Figure 4. It can be arranged accordingly.

The slots 110 are divided into the shortest small slot 111, the medium slot 112, and the longest, based on the length or depth in the radial direction, that is, in the direction outward from the center of the rotor 20. It may be composed of a large slot 123.

The order in which the slots 110 formed in the 1/4 section of the stator 10 are arranged is: small slot 111, medium slot 112, first large slot 123_1, second large slot 123_2, These are the second large slot (123_2), the first large slot (123_1), the medium slot (122), and the small slot (111). Since the type and order in which the slots 111 are arranged are repeated in units of 8 slots, the slot arrangement order is the same for the remaining 3/4 sections of the stator 10. The reason why the large slot 123 is divided into the first large slot 123_1 and the second large slot 12_2 is that the number of times the main coil 121 passes through is different.

As shown in Figures 4 and 5, the slots 110 are arranged so that the main coil 121 and the auxiliary coil 122 are electrically 90 degrees out of phase with each other, and the spacing of the four slots is 45 degrees spatially. It can be wound to pass through.

The slots 110 through which the main coil 121 and the auxiliary coil 122 pass are repeated in units of 1/4 of the stator 10, that is, eight slots. That is, in the eight first to eighth slots (S1 to S8) of FIG. 3, the auxiliary coil 122 is in the first slot (small slot 111), and the main coil is in the second slot (medium slot 112). (121) and the auxiliary coil 122, the main coil 121 and the auxiliary coil 122 in the third slot (the first large slot (113_1)), and the main coil in the fourth slot (the second large slot (113_2)) (121), the main coil 121 in the 5th slot (2nd large slot 113_2), the main coil 121 and the auxiliary coil 122 in the 6th slot (1st large slot 113_1), the 7th The main coil 121 and the auxiliary coil 122 pass through the slot (middle slot 112), and the auxiliary coil 122 passes through the eighth slot (small slot 111). That is, the main coil 121 passes through the middle slot 112, the first large slot 123_1, and the second large slot 123_2, and the auxiliary coil 122 passes through the small slot 111 and the middle slot 112. , passes through the first major slot (123_1).

As shown in Figures 4 and 5, the direction in which the main coil 121 and the auxiliary coil 122 pass through the slots 110 is repeated in 1/2 sections of the stator 10, that is, in units of 16 slots.

Among the 32 slots, in the first eight first to eighth slots (S1 to S8), the auxiliary coil 122 passes through the first slot (small slot 111) in the + direction (or first direction), Both the main coil 121 and the auxiliary coil 122 pass in the + direction in the second slot (middle slot 112), and the main coil 121 and the auxiliary coil pass in the third slot (first major slot 113_1). The coils 122 all pass in the + direction, the main coil 121 passes in the + direction through the fourth slot (the second major slot (113_2)), and the main coil 121 passes through the fifth slot (the second major slot (113_2)). The main coil 121 passes in the + direction, and in the sixth slot (the first major slot 113_1), the main coil 121 passes in the + direction and the auxiliary coil 122 passes in the + direction (or the second direction). The main coil 121 passes in the + direction and the auxiliary coil 122 passes in the + direction in the 7th slot (middle slot 112), and in the 8th slot (small slot 111), the auxiliary coil ( 122) Pass in this direction.

Among the 32 slots, in the second eight first to eighth slots (S9 to S16), the auxiliary coil 122 passes in the - direction through the first slot (small slot 111) (S9), and the second slot Both the main coil 121 and the auxiliary coil 122 pass in the - direction in the (middle slot 112) (S10), and the main coil 121 passes in the third slot (first major slot 113_1) (S11). ) and the auxiliary coil 122 both pass in the - direction, the main coil 121 passes in the - direction in the fourth slot (the second slot (113_2)) (S12), and the fifth slot (the second slot (113_2)) (S12) passes in the - direction. The main coil 121 passes in the - direction through the slot (113_2) (S13), and the main coil (121) passes in the - direction through the sixth slot (the first major slot (113_1)) (S14) and the auxiliary coil. (122) passes in the + direction, the main coil 121 passes in the - direction and the auxiliary coil 122 passes in the + direction to the 7th slot (middle slot 112) (S15), and the 8th slot (Small slot 111) The auxiliary coil 122 passes through (S16) in the + direction.

The direction in which the main coil 121 and the auxiliary coil 122 pass through the first eight slots among the 32 slots is opposite to the direction in which they pass through the second eight slots.

Therefore, the direction through which the main coil 121 and the auxiliary coil 122 pass through the first eight slots and the third eight slots among the 32 slots are the same, and the directions through the second eight slots among the 32 slots are the same. The direction passing through the slots and the direction passing through the fourth eight slots are the same.

Here, the direction in which the coil passes through the slot refers to the direction in which the current of the coil flows in the slot when a current in the plus direction (or minus direction) flows through the coil.

The operating characteristics of a single-phase induction motor, for example, the starting torque, are determined by the size of the current flowing in the main coil, the size of the current flowing in the auxiliary coil, the phase difference between the currents flowing in the main coil and the auxiliary coil, the turns ratio of the main coil and the auxiliary coil, etc. get affected.

If the number of turns of the main coil and auxiliary coil located in the small slot, medium slot, and large slot are different for each slot, the size of the magnetomotive force and spatial harmonic components are determined according to the ratio of the number of turns in the small slot, medium slot, and large slot. Spatial harmonics cause torque pulsation, vibration, noise, and crawling in single-phase induction motors, reducing performance, so it is necessary to design the motor to be as small as possible.

In the embodiment of this specification, in order to reduce the spatial harmonic component caused by the magnetomotive force of the main coil and the auxiliary coil, the ratio of the number of times the main coil and the auxiliary coil pass through the small slot, medium slot, and large slot, that is, the winding ratio or turn Optimize defense.

Figure 6 is a table showing the winding ratio of the main coil and the auxiliary coil for canceling harmonics according to an embodiment of this specification.

As previously explained with reference to FIGS. 4 and 5, the slots through which the main coil 121 and the auxiliary coil 122 pass repeat over 8 slots and are symmetrical around 4 slots. Additionally, the direction in which the main coil 121 and the auxiliary coil 122 pass through the slots is repeated based on 16 slots.

The number of times the main coil 121 and the auxiliary coil 122 pass through the slots is also repeated based on 8 slots, but is symmetrical based on 4 slots. Therefore, the winding ratio of the main coil 121 and the auxiliary coil 122 can be explained based on only four slots.

In Figure 6, the prior art is the winding ratio of the main coil and the auxiliary coil of the single-phase induction motor mass-produced by the applicant company, and the main coil 121 is divided into a double slot 112, a first large slot 113_1, and a second large slot 113_2. ), that is, the winding ratio is 0.233, 0.353, 0.414, and the ratio of the number of times the auxiliary coil 122 passes through the small slot 111, the middle slot 112, and the first large slot 113_1 is They are 0.540, 0.260, and 0.200.

On the other hand, in the single-phase induction motor according to the embodiment of this specification, the turns ratio of the main coil 121, that is, the main coil 121 has a middle slot 112, a first large slot 113_1, and a second large slot 113_2. The ratio of the number of times the auxiliary coil 122 passes through the small slot 111, the middle slot 112, and the first large slot 113_1 is 0.440, 0.300, It is 0.260.

This turns ratio was obtained through much trial and error, resulting in improved performance as shown in Figures 7 to 12.

Figure 7 is a graph showing the magnetomotive force distribution of the main coil, Figure 8 is a graph showing the frequency characteristics of the main coil's magnetomotive force, Figure 9 is a graph showing the magnetomotive force distribution of the auxiliary coil, and Figure 10 is a graph showing the frequency characteristics of the magnetomotive force of the auxiliary coil, Figure 11 is a graph showing the speed and torque characteristics when starting the rotor, and Figure 12 is a graph showing the speed and torque characteristics when operating the rotor at rated speed. It is shown in a graph.

The magnetomotive force distribution in Figures 7 and 9 is determined by the number of spatial turns of the main coil and the auxiliary coil, and Figures 8 and 9 correspond to the frequency characteristics obtained by converting the magnetomotive force distribution in Figures 7 and 9 into the frequency domain.

As shown in Figures 8 and 10, the third harmonic component is greatly reduced in the magnetomotive force of the main coil, and not only the third harmonic component is reduced in the magnetomotive force of the auxiliary coil, but the fifth harmonic component is almost eliminated, resulting in a total harmonic distortion (Total Hamonic) You can see that Distortion: THD) has been greatly improved.

Figure 11 compares the starting torque in the starting operation of driving both the main coil and the auxiliary coil to rotate the rotor in a stationary state and then rotating it to a predetermined RPM with the prior art, showing that the starting torque is improved compared to the prior art. can see.

Figure 12 compares the static torque in the operation of controlling the rotation speed of the rotating rotor within a predetermined section by driving only the main coil with the prior art, and it can be seen that the rated torque has increased compared to the prior art.

As shown in Figures 11 and 12, by improving the harmonic characteristics of the main coil and auxiliary coil, the starting torque and static torque are improved, and the dynamic characteristics of the electric motor are improved.

In this way, by adjusting the turns ratio of the main coil and the auxiliary coil, the harmonic component of the magnetomotive force is minimized, the crawling phenomenon caused by the harmonic torque pulsation of the main coil and the auxiliary coil when starting the rotor is avoided, and the harmonic torque is reduced to start the rotor. Torque and rated torque can be improved.

Since single-phase induction motors do not have magnets in the rotor, they are advantageous in that they can lower manufacturing costs. Additionally, it can be used in products that do not require rotation speed control, such as pumps, compressors, industrial washing machines, freezers, conveyors, and dryer drums.

The single-phase induction motor described in this specification can be described as follows.

A single-phase induction motor according to an embodiment includes a core, a stator including a main winding and an auxiliary winding passing through a plurality of slots provided in the core, and a rotor that rotates by mutual electromagnetic force with the stator. , When classifying a plurality of slots into small slots, medium slots, and large slots based on the depth in the radial direction, the plurality of slots are small slots, medium slots, large slots, large slots, large slots, large slots, medium slots, and a first to fourth unit slot section with the first to eighth slots in the minor slot order as the unit slot section, and the main winding is composed of the second to seventh unit slot sections in the first unit slot section and the third unit slot section. Passes through the slot in the first direction, passes through the 2nd to 7th slots in the second unit slot section and the fourth unit slot section in the second direction opposite to the first direction, and the auxiliary winding passes through the first unit slot section. and passing through the first to third slots in the first direction and the sixth to eighth slots in the second direction in the third unit slot section, and passing through the first to third slots in the second unit slot section and the fourth unit slot section. 3 slots in the second direction and the 6th to 8th slots in the first direction, the number ratios of the main winding passing through the 2nd, 3rd and 4th slots are 0.263, 0.346 and 0.391, and the auxiliary winding The return ratios through these first, second and third slots may be 0.440, 0.300 and 0.260.

In one embodiment, the number of times that at least one of the main winding and the auxiliary winding passes through the first to eighth slots may be the same in each unit slot section.

In one embodiment, the number of times that at least one of the main winding and the auxiliary winding passes through each slot may be symmetrical with respect to the middle of the fourth slot and the fifth slot in each unit slot section.

In one embodiment, a capacitor may be connected in series with the auxiliary winding and the auxiliary winding may be connected in parallel with the main winding.

In one embodiment, a single phase AC power source may be connected to the main winding.

In one embodiment, a switch is connected in series to the auxiliary winding and the capacitor, and the switch may be shorted when the rotor rotates above a predetermined speed.

This specification is not limited to the described embodiments, and it is obvious to those skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the present invention. Accordingly, such modifications or variations should be considered to fall within the scope of the claims of the present invention.

1: single-phase induction motor 10: stator
20: rotor 100: stator core
110: slot 111: small slot
112: Medium slot 113_1, 113_2: Large slot
120: coil 121: main coil
122: Auxiliary coil 200: Rotor core
210: conductor bar 220: shaft hole

Claims (6)

In a single-phase induction motor comprising a core, a stator including a main coil and an auxiliary coil passing through a plurality of slots provided in the core, and a rotor rotating by mutual electromagnetic force with the stator,
When classifying the plurality of slots into small slots, medium slots, and large slots based on the depth in the radial direction, the plurality of slots are the small slot, the medium slot, the large slot, the large slot, and the large slot, It is composed of first to fourth unit slot sections with the first to eighth slots in the order of the large slot, the middle slot, and the small slot as unit slot sections,
The main coil passes through the second to seventh slots in a first direction in the first unit slot section and the third unit slot section, and the second to seventh slots in the second unit slot section and the fourth unit slot section. Passing through the 2nd to 7th slots in a second direction opposite to the first direction,
The auxiliary coil passes through the first to third slots in the first direction and passes through the sixth to eighth slots in the second direction in the first unit slot section and the third unit slot section, Passing through the first to third slots in the second direction and passing through the sixth to eighth slots in the first direction in the second unit slot section and the fourth unit slot section,
The number of times the main coil passes through the second, third, and fourth slots is 0.263, 0.346, and 0.391, and the number of times the auxiliary coil passes through the first, second, and third slots is 0.440, 0.300. and 0.260,
Single phase induction motor. According to claim 1,
A single-phase induction motor wherein the number of times that at least one of the main coil and the auxiliary coil passes through the first to eighth slots is the same in each unit slot section. According to claim 1,
A single-phase induction motor in which the number of times at least one of the main coil and the auxiliary coil passes through each slot is symmetrical with respect to the middle of the fourth slot and the fifth slot in each unit slot section. According to claim 1,
A single-phase induction motor in which a capacitor is connected in series with the auxiliary coil and the auxiliary coil is connected in parallel with the main coil. According to clause 4,
A single-phase induction motor in which a single-phase AC power source is connected to the main coil. According to clause 4,
A single-phase induction motor in which a switch is connected in series to the auxiliary coil and the capacitor, and the switch is short-circuited when the rotor rotates above a predetermined speed.

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