CN107070369B

CN107070369B - Device and method for improving second harmonic current of air conditioner and air conditioner

Info

Publication number: CN107070369B
Application number: CN201710281840.3A
Authority: CN
Inventors: 王中泉; 王世超; 郑绪成
Original assignee: Guangdong Meizhi Compressor Co Ltd
Current assignee: Guangdong Meizhi Compressor Co Ltd
Priority date: 2017-04-26
Filing date: 2017-04-26
Publication date: 2020-01-31
Anticipated expiration: 2037-04-26
Also published as: CN107070369A

Abstract

The invention relates to the technical field of electric appliances, and discloses devices and methods for improving the second harmonic current of an air conditioner and the air conditioner.

Description

Device and method for improving second harmonic current of air conditioner and air conditioner

Technical Field

The invention relates to the technical field of electric appliances, in particular to devices and methods for improving second harmonic current of an air conditioner and the air conditioner.

Background

At present, in an air conditioner, particularly a constant speed air conditioner adopting a single-cylinder compressor, the problem that the second harmonic current exceeds the standard often exists.

The principle that the second harmonic current exists in the air conditioner is as follows: the resistance torque of the pump body of the single-cylinder compressor is not a constant torque, and a large amount of second harmonic exists in the torque component of the resistance torque, so that the motor drags a load (wherein T is T) shown in figure 1_MAs motor torque, T_LLoad torque) and there will be a corresponding large amount of second harmonics in the current.

For the second harmonic current of the air conditioner, the international standard requires that the input current of each phase is less than or equal to 16A, so that the maximum allowable harmonic current correspondingly specified is 1.08A, and most of the current constant-speed air conditioners adopting single-cylinder compressors cannot easily meet the standard. And with the increase of the displacement of the single-cylinder compressor, the larger the current output by the motor is, the more easily the corresponding second harmonic current exceeds the standard.

Aiming at the problem that the secondary harmonic current is easy to exceed the standard, the current main improvement methods have two types:

is a double-cylinder compressor, the pump resistance moment is small, which can improve the second harmonic current;

and secondly, for the condition of the same displacement, a large-machine series compressor is selected, the rotor inertia moment of the compressor is large, and the second harmonic current can be partially improved.

However, the cost of the compressor is far higher than that of a single-cylinder compressor in both double-cylinder compressors and large-engine-series compressors.

Therefore, it is necessary to adopt a new strategy for improving the second harmonic current of the air conditioner using the single cylinder compressor.

Disclosure of Invention

The invention aims to solve the problem that the secondary harmonic current of an air conditioner adopting a single-cylinder compressor is easy to exceed the standard in the prior art, and provides devices and methods for improving the secondary harmonic current of the air conditioner and the air conditioner.

In order to achieve the above object, an aspect of the present invention provides apparatus for improving a second harmonic current of an air conditioner provided with a single cylinder compressor having a single phase asynchronous motor whose main winding is electrically connected to a power supply to form a main winding line and whose sub-winding is electrically connected to the power supply through a th capacitor to form a sub-winding line, the apparatus including a current control circuit provided on the sub-winding line for, when the power supply outputs a negative half cycle current, element-configuring the sub-winding line to increase an effective value of the negative half cycle current output to the single cylinder compressor through the sub-winding line.

Optionally, the current control circuit comprises an th switching piece which is arranged on a line between the power supply and the th capacitor and is used for conducting the line between the power supply and the th capacitor when the power supply outputs positive half-cycle current and disconnecting the line between the power supply and the th capacitor when the power supply outputs negative half-cycle current, and a time delay device which is connected with the th switching piece in parallel and is used for delaying the disconnection of the line when the th switching piece carries out the switching of the disconnection of the line so as to ensure the normal starting of the single-cylinder compressor.

Optionally, the current control circuit comprises an th switching element arranged on a line between the power supply and the th capacitor and used for conducting the line between the power supply and the th capacitor when the power supply outputs positive half-cycle current and disconnecting the line between the power supply and the th capacitor when the power supply outputs negative half-cycle current, a second switching element with a end electrically connected with the power supply and another end electrically connected on a line between the th capacitor and the secondary winding and used for disconnecting the line between the power supply and the secondary winding through the second switching element when the power supply outputs positive half-cycle current and conducting the line between the power supply and the secondary winding through the second switching element when the power supply outputs negative half-cycle current, and a time delay device connected with the th switching element in parallel and used for delaying disconnection of the line when the th switching element performs switching of line disconnection so as to ensure normal starting of the single-cylinder compressor.

Optionally, the second switching part is a switching part, a diode, a triode, or a unidirectional thyristor.

Optionally, the current control circuit includes a second capacitor having a capacitance value smaller than that of the th capacitor and mounted at the th capacitor to replace the th capacitor, a th switching element and a third capacitor, wherein the th switching element is connected in series with the third capacitor and then connected in parallel with the second capacitor, and the th switching element is configured to turn on a line through which the power supply is connected to the secondary winding through the third capacitor when the power supply outputs a positive half-cycle current, and turn off the line through which the power supply is connected to the secondary winding through the third capacitor when the power supply outputs a negative half-cycle current, and a delay device connected in parallel with the th switching element and configured to delay and disconnect the line when the th switching element switches the line off to ensure normal start of the single cylinder compressor, wherein when the line through which the power supply is connected to the secondary winding through the third capacitor is turned on, the second capacitor is connected in parallel with the third capacitor, and a capacitance value of the parallel capacitor is equal to that of the th capacitor.

Optionally, the delay device is a delay switch element or a delay circuit.

Optionally, the th switching element is a switching element, a diode, a triode, or a unidirectional thyristor.

Another aspect of the invention provides a method for improving second harmonic current of an air conditioner configured with a single cylinder compressor having a single phase asynchronous motor having a primary winding electrically connected to a power source to form a primary winding circuit and a secondary winding electrically connected to the power source through a th capacitor to form a secondary winding circuit, the method comprising, while the power source is outputting a negative half cycle current, component configuring the secondary winding circuit to increase an effective value of the negative half cycle current output to the single cylinder compressor via the secondary winding circuit.

Optionally, the configuring the secondary winding line comprises arranging a switching piece on a line between the power supply and the th capacitor, controlling the th switching piece to conduct the line between the power supply and the th capacitor when the power supply outputs a positive half-cycle current and to disconnect the line between the power supply and the th capacitor when the power supply outputs a negative half-cycle current, arranging a time delay device in parallel with the th switching piece, and controlling the time delay device to delay the disconnection of the line to ensure normal starting of the single-cylinder compressor when the switching piece performs the switching of the line disconnection.

Optionally, the configuring the elements of the secondary winding line comprises arranging a switching member on a line between the power supply and the th capacitor, controlling the switching member to switch on the line between the power supply and the th capacitor when the power supply outputs a positive half cycle current and switch off the line between the power supply and the th capacitor when the power supply outputs a negative half cycle current, arranging a second switching member having a end electrically connected to the power supply and another end electrically connected to a line between the th capacitor and the secondary winding, controlling the second switching member to switch off the line between the power supply and the secondary winding through the second switching member when the power supply outputs a positive half cycle current and switch on a line between the power supply and the secondary winding through the second switching member when the power supply outputs a negative half cycle current, arranging a time delay device connected in parallel with the th element, and controlling the time delay device to switch off the line to ensure normal switching of the single-cylinder compressor when the power supply outputs a negative half cycle current, and controlling the time delay device to switch off the single-phase switching member .

Optionally, the configuring the elements of the secondary winding line includes setting a capacitance value smaller than the th capacitor and installing the second capacitor at the th capacitor instead of the th capacitor, setting a th switching piece and a third capacitor connected in series and connecting the th switching piece and the third capacitor in parallel with the second capacitor, controlling the th switching piece to switch on the line connecting the power supply and the secondary winding through the third capacitor when the power supply outputs a positive half-cycle current and switch off the line connecting the power supply and the secondary winding through the third capacitor when the power supply outputs a negative half-cycle current, setting a delay device connected in parallel with the th switching piece, and controlling the delay device to delay and disconnect the line when the th switching piece switches off the line to ensure normal start of the single-cylinder compressor, wherein when the line connecting the power supply and the secondary winding through the third capacitor is switched on, the second capacitor and the third capacitor are connected in parallel, and the capacitance value of the second capacitor is equal to in parallel after the third capacitor is switched off.

Another aspect of the present invention provides air conditioner equipped with a single cylinder compressor having a single phase asynchronous motor whose main winding is electrically connected to a power source to form a main winding line and whose sub-winding is electrically connected to the power source through a th capacitor to form a sub-winding line, and the air conditioner further provided with the above-mentioned apparatus for improving the second harmonic current of the air conditioner.

Through the technical scheme, the invention has the beneficial effects that: the invention sets a mechanism for increasing the negative half-cycle current output to the compressor, and reduces the difference between the effective value of the positive half-cycle current and the effective value of the negative half-cycle current, thereby improving the second harmonic current.

Drawings

The accompanying drawings are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this specification , which together with the following detailed description serve to explain, but are not to limit, embodiments of the invention.

FIG. 1 is an exemplary diagram of a single cylinder compressor with motor drive;

FIG. 2 is a schematic current waveform for a single cylinder compressor;

FIG. 3 is an exploded view of the current waveform of the single cylinder compressor;

FIG. 4 is a schematic diagram of a power supply mode of a conventional single-phase asynchronous motor;

fig. 5 is a schematic structural view of an apparatus for improving a second harmonic current of an air conditioner according to an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of an th preferred element configuration of an apparatus for improving the second harmonic current of an air conditioner according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a device for improving the second harmonic current of an air conditioner according to a second preferred element configuration of the embodiment of the present invention;

fig. 8 is a schematic structural diagram of a device for improving the second harmonic current of an air conditioner according to a third preferred element configuration of the embodiment of the present invention; and

fig. 9, fig. 10 and fig. 11 are schematic diagrams illustrating a flow of configuring components for the secondary winding circuit according to an embodiment of the present invention.

Description of the reference numerals

11 primary winding 12 secondary winding

th capacitor of 20 power supply 31

32 second capacitance 33 third capacitance

40 current control circuit 41 th switching piece

42 time delay device 43 second switching piece

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

In the present invention, the reference to " th, second" etc. is used for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

In addition, in the present invention, the positive half-cycle current (or waveform) and the negative half-cycle current (or waveform) are referred to as the current with positive amplitude in the current cycles of the alternating current and the current with negative amplitude in the half cycle, respectively, and the amplitudes of the two are different.

The current waveform of the single-cylinder compressor is analyzed in the process of implementing the present application, and as shown in fig. 2, it can be known that the positive half-cycle waveform and the negative half-cycle waveform of the single-cylinder compressor are asymmetric. The asymmetric waveform is subjected to harmonic decomposition, and the decomposition result is shown in fig. 3, which shows that the second harmonic current exceeding the standard appears. Therefore, the inventor analyzes the result and proposes a strategy for improving the second harmonic current by improving the difference between the positive half-cycle waveform and the negative half-cycle waveform of the single-cylinder compressor.

Based on the invention concept, the embodiment of the invention provides devices for improving the second harmonic current of an air conditioner, wherein the air conditioner is provided with a single-cylinder compressor with a single-phase asynchronous motor, and in steps, as shown in fig. 4, a main winding 11 of the single-phase asynchronous motor is electrically connected with a power supply 20 to form a main winding circuit, a secondary winding 12 is electrically connected with the power supply 20 through a capacitor 31 to form a secondary winding circuit, and the main winding circuit and the secondary winding circuit are matched to output current to drive the compressor to work, and the situation shown in fig. 4 is the power supply mode of a conventional single-phase asynchronous motor.

Fig. 5 illustrates a structure of an apparatus for improving a second harmonic current of an air conditioner according to an embodiment of the present invention. As shown in fig. 5, the apparatus includes: a current control circuit 40 disposed on the secondary winding wire for component configuring the secondary winding wire to increase an effective value of the negative half cycle current outputted to the single cylinder compressor through the secondary winding wire when the power source 20 outputs the negative half cycle current.

Specifically, when the compressor is started and the power supply outputs a positive half-cycle current, fig. 4 is the same as the case shown in fig. 5, but when the power supply outputs a negative half-cycle current, the negative half-cycle current is increased by the action of the current control circuit, so that the difference between the effective value of the positive half-cycle current and the effective value of the negative half-cycle current is reduced, the finally decomposed second harmonic current is less than 1.08A, and the requirement of the international standard is met.

Under the premise of the invention idea of increasing the effective value of the negative half-cycle current output to the single-cylinder compressor through the secondary winding wire, a person skilled in the art can randomly configure a circuit or a module to achieve the purpose of the invention idea.

In th preferred element configuration, as shown in fig. 6, the current control circuit 40 may include a switching member 41 provided on a line between the power source 20 and the th capacitor 31 for conducting the line between the power source 20 and the th capacitor 31 when the power source 20 outputs a positive half cycle current and for disconnecting the line between the power source 20 and the th capacitor 31 when the power source 20 outputs a negative half cycle current, and a delay means 42 connected in parallel with the th switching member 41 for delaying the disconnection of the line to ensure a normal start of the single cylinder compressor when the th switching member 41 performs the switching of the disconnection of the line.

Specifically, when the power source 20 outputs a positive half cycle current, the th switching member 41 turns on the line between the power source 20 and the th capacitor 31 so that the positive half cycle current in this case corresponds to in the case of the conventional single-phase asynchronous motor shown in fig. 4, and thus the values of the positive half cycle current finally output to the compressor are the same in the case of the other conditions , whereas when the power source 20 outputs a negative half cycle current, the th switching member 41 turns off the line between the power source 20 and the th capacitor 31 so that the negative half cycle current output from the power source 20 does not pass through the th capacitor 31 and the secondary winding 21, and is not phase-shifted by the th capacitor 31 and consumed by the secondary winding 21, and the value of the negative half cycle current output to the compressor is increased relative to the conventional single-phase asynchronous motor shown in fig. 4, i.e., the effective value of the negative half cycle current output to the single-cylinder compressor via the secondary winding line is increased.

Accordingly, the switching element 41 is designed to perform unidirectional conduction, i.e., conduct the corresponding circuit only during the positive half cycle, therefore, in the embodiment of the present invention, a diode, a triode, or a unidirectional thyristor capable of performing unidirectional conduction can be used as the switching element, or controllable switching elements can be used, and a diode is preferably used here, which has low cost and good unidirectional conductivity, and the use of a triode and a unidirectional thyristor as a diode with unidirectional conductivity in some cases is a conventional technical means in the art, and will not be described herein again.

, the delay device 42 can avoid the compressor from starting normally due to the fluctuation of the negative half-cycle current at the moment of the circuit breaking.

Accordingly, it is understood that the delay device 42 herein implements a signal delay function, and can be implemented by using a delay switch element or a delay circuit, wherein there are various delay switches and conventional delay circuits constructed by a timer, a resistor, an th capacitor, etc., and thus, it will not be described in detail herein.

In a second preferred component configuration, as shown in fig. 7, the current control circuit comprises a switching piece 41 and a time delay device 42, which are similar to those of the preferred component configuration, and a second switching piece 43, of which end is electrically connected to the power supply 20, and the other end is electrically connected to the line between the th capacitor 31 and the secondary winding 12, for disconnecting the line connecting the power supply with the secondary winding 12 via the second switching piece 43 when the power supply 20 outputs a positive half-cycle current, and for connecting the line connecting the power supply 20 with the secondary winding 12 via the second switching piece 43 when the power supply outputs a negative half-cycle current.

The second switching part may also adopt a switching part, a diode, a triode or a unidirectional thyristor.

Referring to fig. 7, the second switching member 43 is engaged with the th switching member 41, but the cut-off directions of the two are opposite, when the power source 20 outputs a positive half cycle current, the th switching member 41 is turned on, and the second switching member 43 is turned off, so that the positive half cycle current normally passes through the th capacitor 31 and the sub-winding 12, which corresponds to the case of the conventional single-phase asynchronous motor shown in fig. 4, when the power source 20 outputs a negative half cycle current, the th switching member 41 is turned off, and the second switching member 43 is turned on, so that the negative half cycle current can pass through the second switching member 43 and pass through the sub-winding 12, but cannot pass through the th capacitor 31, and thus is not phase-shifted by the th capacitor 31, so that the negative half cycle current output to the compressor is relatively increased, compared to the case of the conventional single-phase asynchronous motor shown in fig. 4, but the negative half cycle current is still consumed by the sub-winding 12, so that the increase of the negative half cycle current is not as compared to the case.

In a third preferred component configuration, as shown in fig. 8, the current control circuit comprises a second capacitor 32 having a smaller capacitance value than the th capacitor 31 and mounted at the position of the th capacitor 31 to replace the th capacitor, a th switching element 41 and a third capacitor 33, wherein the th switching element 41 is connected in series with the third capacitor 33 and then connected in parallel with the second capacitor 32, and the th switching element 41 is used for conducting the line connecting the power source to the secondary winding via the third capacitor when the power source outputs a positive half cycle current and disconnecting the line connecting the power source to the secondary winding via the third capacitor when the power source outputs a negative half cycle current, and a delay device 42 connected in parallel with the th switching element 41 and used for delaying the disconnection of the line when the th switching element 41 performs a line disconnection switch to ensure a normal start of the single cylinder compressor, wherein the capacitance value of the line connecting the power source 20 to the secondary winding 33 is equal to that of the third capacitor 33 and the third capacitor 33 is connected in parallel with the line connected in parallel with the third capacitor .

Here, the use of the delay device 42 is similar to the and the second preferred component configurations described above and will not be described in detail.

Specifically, when the power supply 20 outputs a positive half cycle current, the diode is turned on, the lines of the second capacitor 32 and the third capacitor 33 are both turned on, and the capacitance values of the second capacitor 32 and the third capacitor 33 after being connected in parallel are equal to that of the -th capacitor 31, so that the secondary winding line at this time corresponds to shown in the case of the conventional single-phase asynchronous motor shown in fig. 4, and therefore, the values of the positive half cycle current finally output to the compressor are the same under other conditions .

With the above three preferred element arrangements, the current directions indicated by the arrows in the corresponding drawings are the directions of the positive half cycle currents, and the negative half cycle currents output through the secondary winding lines are set to I1, I2 and I3 in this order, and further, when the negative half cycle currents output through the secondary winding lines in the case of fig. 4 are set to I, I1> I2> I3> I is known from the degrees to which the negative half cycle currents output through the secondary winding lines are increased, respectively.

Therefore, the preferred element arrangements shown in fig. 6 to 8 can be determined according to the degree to which the positive half-cycle current effective value is greater than the negative half-cycle current effective value.

In summary, the device according to the embodiment of the present invention reduces the difference between the effective value of the positive half cycle current and the effective value of the negative half cycle current by increasing the negative half cycle current, thereby improving the second harmonic current and ensuring the normal start of the compressor.

Based on the same inventive concept as the above-mentioned device for improving the second harmonic current of an air conditioner, another embodiment of the present invention further provides a method for improving the second harmonic current of an air conditioner, also directed to the above-mentioned air conditioner configured with a single cylinder compressor having a single phase asynchronous motor.

In addition, the situation that the power supply outputs positive half cycle current is the same as the positive half cycle current passing mode of the conventional single-phase asynchronous motor, and the situation is not described in more detail here.

Preferably, as shown in fig. 9, the element configuration of the secondary winding line may include the steps of:

step S901, a th switching element is disposed on a line between the power source and the th capacitor.

Step S902, controlling the switching element to connect the power source to the th capacitor when the power source outputs a positive half cycle current, and to disconnect the power source to the th capacitor when the power source outputs a negative half cycle current.

And step S903, arranging a time delay device connected with the th switching piece in parallel.

And step S904, controlling the time delay device to delay the disconnection of the line to ensure the normal start of the single-cylinder compressor when the th switching piece switches the disconnection of the line.

More preferably, as shown in fig. 10, the element configuration of the secondary winding line may include the steps of:

step S1001, a switching piece is arranged on a line between the power supply and the th capacitor.

Step S1002, controlling the switching element to connect the power supply to the th capacitor when the power supply outputs a positive half cycle current, and to disconnect the power supply to the th capacitor when the power supply outputs a negative half cycle current.

Step S1003, a second switching element is provided, in which end of the second switching element is electrically connected to the power supply, and end of the second switching element is electrically connected to the line between the th capacitor and the secondary winding.

Step S1004, controlling the second switching part to disconnect the line of the power supply connected to the secondary winding through the second switching part when the power supply outputs a positive half-cycle current, and to connect the line of the power supply connected to the secondary winding through the second switching part when the power supply outputs a negative half-cycle current.

In step S1005, a delay device connected in parallel to the th switching piece is provided.

Step S1006, controlling the time delay device to make the circuit break in a time delay manner when the th switching piece switches the circuit break, so as to ensure the normal start of the single-cylinder compressor.

More preferably, as shown in fig. 11, the element configuration of the secondary winding line may include the steps of:

step S1101, setting a capacitance value smaller than the th capacitor, and installing the second capacitor to the th capacitor instead of the th capacitor.

Step S1102, a th switching element and a third capacitor are connected in series, and the th switching element and the third capacitor are connected in parallel with the second capacitor after being connected in series.

Step S1103, controlling the switching element to switch on the line connecting the power supply to the secondary winding via the third capacitor when the power supply outputs a positive half-cycle current, and to switch off the line connecting the power supply to the secondary winding via the third capacitor when the power supply outputs a negative half-cycle current.

And step S1104, a delay device connected in parallel with the th switching piece is provided.

And step S1105, controlling the time delay device to make the circuit break in a time delay manner to ensure the normal start of the single-cylinder compressor when the th switching piece switches the circuit break.

When the power supply is switched on, the second capacitor is connected in parallel with the third capacitor when the power supply is connected with a circuit connected with the secondary winding through the third capacitor, and the capacitance value after the parallel connection is equal to that of the th capacitor.

It should be noted that the execution sequence among the above steps may be adjusted according to the actual situation, and the embodiment of the present invention is not limited thereto.

In addition, in the case of not conflicting with the idea of the present invention of "increasing the effective value of the negative half cycle current outputted to the single cylinder compressor through the secondary winding wire", those skilled in the art may also adopt other control methods, and the present invention is not limited thereto.

It should be noted that, for details of the implementation and technical effects of the method for improving the second harmonic current of the air conditioner of the present embodiment, reference may be made to the above-mentioned embodiment of the apparatus for improving the second harmonic current of the air conditioner, and details are not repeated herein.

In addition, another embodiment of the present invention further provides air conditioners, which are configured with a single cylinder compressor having a single phase asynchronous motor, a main winding of the single phase asynchronous motor is electrically connected with a power supply to form a main winding circuit, and a secondary winding is electrically connected with the power supply through a th capacitor to form a secondary winding circuit, and the air conditioners are further provided with the apparatus for improving the second harmonic current of the air conditioners according to the above embodiments.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

An apparatus for improving a second harmonic current of an air conditioner equipped with a single cylinder compressor having a single phase asynchronous motor whose main winding is electrically connected to a power source to form a main winding line and whose sub winding is electrically connected to the power source through a th capacitor to form a sub winding line, comprising:

and the current control circuit is arranged on the auxiliary winding circuit and used for carrying out component configuration on the auxiliary winding circuit according to the degree that the effective value of the positive half-cycle current output to the single-cylinder compressor by the power supply through the auxiliary winding circuit is greater than the effective value of the corresponding negative half-cycle current when the power supply outputs the negative half-cycle current so as to increase the effective value of the negative half-cycle current output to the single-cylinder compressor through the auxiliary winding circuit.
2. The apparatus of claim 1, wherein the current control circuit comprises:

an switching element arranged on the line between the power supply and the th capacitor for switching on the line between the power supply and the th capacitor when the power supply outputs a positive half cycle current and switching off the line between the power supply and the th capacitor when the power supply outputs a negative half cycle current, and

and the time delay device is connected with the th switching piece in parallel and is used for delaying the disconnection of the circuit when the th switching piece switches the disconnection of the circuit so as to ensure the normal starting of the single-cylinder compressor.
3. The apparatus of claim 1, wherein the current control circuit comprises:

an switching element, disposed on the line between the power source and the th capacitor, for switching on the line between the power source and the th capacitor when the power source outputs a positive half cycle current, and for switching off the line between the power source and the th capacitor when the power source outputs a negative half cycle current;

a second switching piece with end electrically connected to the power supply and end electrically connected to the circuit between the th capacitor and the secondary winding for disconnecting the circuit connected to the secondary winding via the second switching piece when the power supply outputs positive half cycle current and connecting the circuit connected to the secondary winding via the second switching piece when the power supply outputs negative half cycle current, and

and the time delay device is connected with the th switching piece in parallel and is used for delaying the disconnection of the circuit when the th switching piece switches the disconnection of the circuit so as to ensure the normal starting of the single-cylinder compressor.
4. The apparatus of claim 3, wherein the second switch is a diode, a triode, or a unidirectional thyristor.
5. The apparatus of claim 1, wherein the current control circuit comprises:

a second capacitor having a capacitance value smaller than the th capacitor and mounted to the th capacitor in place of the th capacitor;

a th switching element and a third capacitor, wherein the th switching element is connected in series with the third capacitor and then connected in parallel with the second capacitor, and the th switching element is used for switching on the line of the power supply connected with the secondary winding through the third capacitor when the power supply outputs positive half-cycle current and switching off the line of the power supply connected with the secondary winding through the third capacitor when the power supply outputs negative half-cycle current, and

a time delay device, connected in parallel with the th switching piece, for delaying the disconnection of the line when the th switching piece switches the disconnection of the line to ensure the normal start of the single cylinder compressor;

when the power supply is switched on, the second capacitor is connected in parallel with the third capacitor when the power supply is connected with a circuit connected with the secondary winding through the third capacitor, and the capacitance value after the parallel connection is equal to that of the th capacitor.
6. The device of any of of claims 2-5, wherein the delay device is a delay switch element or a delay circuit.
7. The apparatus of any of , wherein the switching element is a diode, a triode, or a unidirectional thyristor.
8, A method for improving the second harmonic current of an air conditioner equipped with a single cylinder compressor having a single phase asynchronous motor whose main winding is electrically connected to a power source to form a main winding line and whose secondary winding is electrically connected to the power source through a th capacitor to form a secondary winding line, the method comprising:

when the power supply outputs a negative half cycle current, the secondary winding circuit is configured to increase the effective value of the negative half cycle current output to the single cylinder compressor through the secondary winding circuit according to the degree to which the effective value of the positive half cycle current output to the single cylinder compressor through the secondary winding circuit by the power supply is greater than the effective value of the corresponding negative half cycle current.
9. The method of claim 8, wherein the component configuring the secondary winding circuit comprises:

providing a switching element on a line between the power source and the th capacitor;

controlling the switch to connect the power supply to the th capacitor when the power supply is outputting a positive half cycle current and to disconnect the power supply from the th capacitor when the power supply is outputting a negative half cycle current;

providing a time delay device in parallel with said th switch, and

and the time delay device is controlled to lead the circuit to be disconnected in a time delay manner when the th switching piece carries out switching of disconnection of the circuit so as to ensure the normal starting of the single-cylinder compressor.
10. The method of claim 8, wherein the component configuring the secondary winding circuit comprises:

providing a switching element on a line between the power source and the th capacitor;

controlling the switch to connect the power supply to the th capacitor when the power supply is outputting a positive half cycle current and to disconnect the power supply from the th capacitor when the power supply is outputting a negative half cycle current;

a second switching piece is arranged, wherein an end of the second switching piece is electrically connected with the power supply, and the other end of the second switching piece is electrically connected with a line between the th capacitor and the secondary winding;

controlling the second switching piece to disconnect a line of the power supply connected with the secondary winding through the second switching piece when the power supply outputs positive half-cycle current, and to connect the line of the power supply connected with the secondary winding through the second switching piece when the power supply outputs negative half-cycle current;

providing a time delay device in parallel with said th switch, and

and the time delay device is controlled to lead the circuit to be disconnected in a time delay manner when the th switching piece carries out switching of disconnection of the circuit so as to ensure the normal starting of the single-cylinder compressor.
11. The method of claim 10, wherein the second switching element is a diode, a triode, or a unidirectional thyristor.
12. The method of claim 8, wherein the component configuring the secondary winding circuit comprises:

setting a second capacitor with a capacitance value smaller than that of the th capacitor, and installing the second capacitor at the position of the th capacitor to replace the th capacitor;

arranging an th switching piece and a third capacitor in series, and connecting the th switching piece and the third capacitor in parallel with the second capacitor after series connection;

controlling the switching element to connect the power supply to the secondary winding via the third capacitor when the power supply outputs a positive half cycle current, and to disconnect the power supply from the secondary winding via the third capacitor when the power supply outputs a negative half cycle current;

providing a time delay device in parallel with said th switch, and

controlling the time delay device to make the circuit break in a time delay manner when the th switching piece switches the circuit break so as to ensure the normal starting of the single-cylinder compressor;

when the power supply is switched on, the second capacitor is connected in parallel with the third capacitor when the power supply is connected with a circuit connected with the secondary winding through the third capacitor, and the capacitance value after the parallel connection is equal to that of the th capacitor.
13. The method of any of , wherein the switching element is a diode, a triode, or a unidirectional thyristor.
14.. air conditioner provided with a single cylinder compressor having a single phase asynchronous motor whose main winding is electrically connected to a power source to form a main winding circuit and whose secondary winding is electrically connected to said power source through a th capacitor to form a secondary winding circuit, characterized in that the air conditioner is further provided with the device of any of claims 1 to 7.