1. An expansion valve connection detection circuit (100) is characterized in that the expansion valve connection detection circuit (100) comprises a main control chip (110), a control chip (120) and at least one connection detection module (130), wherein the main control chip (110) is electrically connected with a first pin of the control chip (120), the connection detection module (130) is electrically connected with a second pin of the control chip (120), the second pin of the control chip (120) is also used for being electrically connected with an electronic expansion valve (140), and the connection detection module (130) is also electrically connected with a first driving power supply and the main control chip (110); wherein the content of the first and second substances,

the main control chip (110) is used for sending a control signal to the control chip (120) so as to control the working state of the electronic expansion valve (140) through the control chip (120);

the connection detection module (130) is configured to generate a first signal or a second signal according to a connection state of the second pin and the electronic expansion valve (140) when the control chip (120) is in a detection mode, where the first signal and the second signal are opposite signals;

the main control chip (110) is further configured to determine that the second pin is normally connected to the electronic expansion valve (140) when receiving the first signal; and when the second signal is received, determining that the second pin is abnormally connected with the electronic expansion valve (140).

2. The expansion valve connection detection circuit (100) according to claim 1, wherein the connection detection module (130) comprises a transistor (Q1), a first resistor (R1), a second resistor (R2), a third resistor (R3) and a fourth resistor (R4), one end of the first resistor (R1) is electrically connected to the second pin, the other end of the first resistor (R1) is electrically connected to the base of the transistor (Q1) and one end of the second resistor (R2), the other end of the second resistor (R2) is grounded, the emitter of the transistor (Q1) is grounded, the collector of the transistor (Q1) is electrically connected to the third resistor (R3) and one end of the fourth resistor (R4), the other end of the third resistor (R3) is electrically connected to the first driving power supply, and the other end of the fourth resistor (R4) is electrically connected to the main control chip (110), the electronic expansion valve (140) is also connected with a second driving power supply; wherein the content of the first and second substances,

when the main control chip (110) receives a high level, determining that the second pin is abnormally connected with the electronic expansion valve (140);

when the main control chip (110) receives a low level, the second pin is determined to be normally connected with the electronic expansion valve (140).

3. The expansion valve connection detection circuit (100) of claim 2, wherein the second driving power source is larger than the first driving power source, the connection detection module (130) further comprising a diode (D1), wherein an anode of the diode (D1) is electrically connected to a base of the transistor (Q1), and a cathode of the diode (D1) is electrically connected to the first driving power source.

4. Expansion valve connection detection circuit (100) according to claim 1, the connection detection module (130) comprises an optical coupler (U2), a fifth resistor (R5), a sixth resistor (R6) and a seventh resistor (R7), the optocoupler (U2) comprises a light emitting diode (D1) and a light receiving triode (Q1), one end of the fifth resistor (R5) is electrically connected with the second pin, the other end of the fifth resistor (R5) is electrically connected with the anode of the light emitting diode (D1), the cathode of the light emitting diode (D1) is grounded, the collector of the light receiving triode (Q1) is electrically connected with the first driving power supply, the emitting electrodes of the light receiving triode (Q1) are respectively and electrically connected with one ends of the sixth resistor (R6) and the seventh resistor (R7), the other end of the sixth resistor (R6) is grounded, and the other end of the seventh resistor (R7) is electrically connected with the main control chip (110); wherein the content of the first and second substances,

when the main control chip (110) receives a high level, determining that the second pin is normally connected with the electronic expansion valve (140);

when the main control chip (110) receives a low level, it is determined that the second pin is abnormally connected with the electronic expansion valve (140).

5. The expansion valve connection detection circuit (100) according to claim 4, wherein the connection detection module (130) further comprises a capacitor, one end of the capacitor is electrically connected to the other end of the seventh resistor (R7), and the other end of the capacitor is grounded.

6. The expansion valve connection detection circuit (100) according to claim 1, wherein the electronic expansion valve (140) comprises four phases, the number of the second pins and the connection detection modules (130) is four, each of the second pins is electrically connected to one phase of one of the connection detection modules (130) and the electronic expansion valve (140), and each of the connection detection modules (130) is electrically connected to the main control chip (110).

7. An air conditioner characterized by comprising an expansion valve connection detection circuit (100) according to any one of claims 1 to 6.

8. An expansion valve connection detection method applied to a main control chip (110) of an expansion valve connection detection circuit (100) according to any one of claims 1 to 6, the method comprising:

controlling the control chip (120) to enter a detection mode;

determining the connection state of the second pin and the electronic expansion valve (140) according to the received signal sent by the connection detection module (130); wherein the content of the first and second substances,

when the first signal is received, determining that the second pin is normally connected with the electronic expansion valve (140);

and when the second signal is received, determining that the second pin is abnormally connected with the electronic expansion valve (140), wherein the first signal and the second signal are opposite signals.

9. The expansion valve connection detection method according to claim 8, wherein the step of determining the connection state of the second pin with the electronic expansion valve (140) according to the received signal sent by the connection detection module (130) comprises:

when receiving a high level, determining that the second pin is abnormally connected with the electronic expansion valve (140);

when a low level is received, determining that the second pin is normally connected with the electronic expansion valve (140); or

When receiving a high level, determining that the second pin is normally connected with the electronic expansion valve (140);

and when a low level is received, determining that the second pin is abnormally connected with the electronic expansion valve (140).

10. The method is applied to a main control chip (110) of an expansion valve connection detection circuit (100), the expansion valve connection detection circuit (100) further comprises a control chip (120) and at least one connection detection module (130), the main control chip (110) is electrically connected with a first pin of the control chip (120), the connection detection module (130) is electrically connected with a second pin of the control chip (120), the second pin of the control chip (120) is also used for being electrically connected with an electronic expansion valve (140), and the connection detection module (130) is also electrically connected with a first driving power supply and the main control chip (110); the method comprises the following steps:

acquiring the proportion of a first signal and a second signal which are sent by the connection detection module (130) and received in a fixed period of operation of the electronic expansion valve (140); wherein the first signal and the second signal are opposite signals;

and determining the connection state of the second pin and the electronic expansion valve (140) according to the proportion and a preset proportion.

Background

When the existing air conditioner works, the control on the electronic expansion valve belongs to active control, whether the electronic expansion valve is normally connected or not cannot be detected, and when the electronic expansion valve is not normally connected, the refrigerating and heating effects of the air conditioner can be influenced, and even the air conditioner system can be damaged.

For example, when the electronic expansion valve is not normally connected to the control chip, the electronic expansion valve may not work normally, which may cause damage to the air conditioning system.

In summary, there is a problem in the prior art that the electronic expansion valve may be improperly wired.

Disclosure of Invention

The application aims to provide an expansion valve connection detection circuit, an expansion valve connection detection method and an air conditioner, and aims to solve the problem that an electronic expansion valve in the prior art is possibly connected abnormally.

In order to solve the above problem, in a first aspect, an embodiment of the present application provides an expansion valve connection detection circuit, where the expansion valve connection detection circuit includes a main control chip, a control chip, and at least one connection detection module, the main control chip is electrically connected to a first pin of the control chip, the connection detection module is electrically connected to a second pin of the control chip, the second pin of the control chip is further used for being electrically connected to an electronic expansion valve, and the connection detection module is further electrically connected to a first driving power supply and the main control chip; the main control chip is used for sending a control signal to the control chip so as to control the working state of the electronic expansion valve through the control chip; the connection detection module is used for generating a first signal or a second signal according to the connection state of the second pin and the electronic expansion valve when the control chip is in a detection mode, wherein the first signal and the second signal are opposite signals; the main control chip is further used for determining that the second pin is normally connected with the electronic expansion valve when the first signal is received; and when the second signal is received, determining that the second pin is abnormally connected with the electronic expansion valve.

Because the connection detection module is arranged in the expansion valve connection detection circuit provided by the application, whether the electronic expansion valve is normally connected or not can be detected by utilizing the connection detection module. Meanwhile, the connection detection module is connected with the second pin, so that when the main control chip controls the working state of the electronic expansion valve, the work of the electronic expansion valve cannot be influenced.

Optionally, the connection detection module includes a triode, a first resistor, a second resistor, a third resistor and a fourth resistor, one end of the first resistor is electrically connected to the second pin, the other end of the first resistor is electrically connected to the base of the triode and one end of the second resistor respectively, the other end of the second resistor is grounded, the emitter of the triode is grounded, the collector of the triode is electrically connected to one end of the third resistor and one end of the fourth resistor respectively, the other end of the third resistor is electrically connected to the first driving power supply, the other end of the fourth resistor is electrically connected to the main control chip, and the electronic expansion valve is further connected to a second driving power supply; wherein the content of the first and second substances,

when the main control chip receives a high level, determining that the second pin is abnormally connected with the electronic expansion valve;

and when the main control chip receives a low level, determining that the second pin is normally connected with the electronic expansion valve.

Optionally, the second driving power supply is larger than the first driving power supply, the connection detection module further includes a diode, an anode of the diode is electrically connected to a base of the triode, and a cathode of the diode is electrically connected to the first driving power supply.

Optionally, the connection detection module includes an optocoupler, a fifth resistor, a sixth resistor, and a seventh resistor, the optocoupler includes a light emitting diode and a light receiving triode, one end of the fifth resistor is electrically connected to the second pin, the other end of the fifth resistor is electrically connected to an anode of the light emitting diode, a cathode of the light emitting diode is grounded, a collector of the light receiving triode is electrically connected to the first driving power supply, an emitter of the light receiving triode is electrically connected to one end of the sixth resistor and one end of the seventh resistor, the other end of the sixth resistor is grounded, and the other end of the seventh resistor is electrically connected to the main control chip; wherein the content of the first and second substances,

when the main control chip receives a high level, determining that the second pin is normally connected with the electronic expansion valve;

and when the main control chip receives a low level, determining that the second pin is abnormally connected with the electronic expansion valve.

Optionally, the connection detection module further includes a capacitor, one end of the capacitor is electrically connected to the other end of the seventh resistor, and the other end of the capacitor is grounded.

Optionally, the electronic expansion valve includes four phases, the number of the second pins and the connection detection modules is four, and each of the second pins is electrically connected to one phase of the connection detection module and the electronic expansion valve, and each of the connection detection modules is electrically connected to the main control chip.

In a second aspect, an embodiment of the present application further provides an air conditioner, where the air conditioner includes the above expansion valve connection detection circuit.

In a third aspect, an embodiment of the present application further provides an expansion valve connection detection method, which is applied to the main control chip of the expansion valve connection detection circuit, where the method includes:

controlling the control chip to enter a detection mode;

determining the connection state of the second pin and the electronic expansion valve according to the received signal sent by the connection detection module; wherein the content of the first and second substances,

when the first signal is received, determining that the second pin is normally connected with the electronic expansion valve;

and when the second signal is received, determining that the second pin is abnormally connected with the electronic expansion valve, wherein the first signal and the second signal are opposite signals.

Optionally, the step of determining the connection state of the second pin and the electronic expansion valve according to the received signal sent by the connection detection module includes:

when receiving a high level, determining that the second pin is abnormally connected with the electronic expansion valve;

when receiving a low level, determining that the second pin is normally connected with the electronic expansion valve; or

When receiving a high level, determining that the second pin is normally connected with the electronic expansion valve;

and when a low level is received, determining that the second pin is abnormally connected with the electronic expansion valve.

In a fourth aspect, an embodiment of the present application further provides an expansion valve connection detection method, where the method is applied to a main control chip of an expansion valve connection detection circuit, the expansion valve connection detection circuit further includes a control chip and at least one connection detection module, the main control chip is electrically connected to a first pin of the control chip, the connection detection module is electrically connected to a second pin of the control chip, the second pin of the control chip is further used for being electrically connected to an electronic expansion valve, and the connection detection module is further electrically connected to a first driving power supply and the main control chip; the method comprises the following steps:

acquiring the proportion of a first signal and a second signal which are sent by the connection detection module and received in a fixed period of operation of the electronic expansion valve; wherein the first signal and the second signal are opposite signals;

and determining the connection state of the second pin and the electronic expansion valve according to the proportion and a preset proportion. .

Drawings

Fig. 1 is an equivalent circuit diagram of an electronic expansion valve in the prior art.

Fig. 2 is a schematic diagram of a driving chip of an electronic expansion valve in the prior art.

Fig. 3 is a schematic block diagram of an expansion valve connection detection circuit according to an embodiment of the present disclosure.

Fig. 4 is a schematic diagram of a main control chip and a control chip provided in an embodiment of the present application.

Fig. 5 is a schematic circuit diagram of a connection detection module according to an embodiment of the present disclosure.

Fig. 6 is another circuit schematic diagram of a connection detection module according to an embodiment of the present disclosure.

Fig. 7 is a schematic flowchart of a method for detecting connection of an expansion valve according to an embodiment of the present disclosure.

Fig. 8 is another schematic flow chart of a method for detecting connection of an expansion valve according to an embodiment of the present disclosure.

Description of reference numerals:

100-expansion valve connection detection circuit; 110-a master control chip; 120-a control chip; 130-connection detection module; 140-an electronic expansion valve; r1 — first resistance; r2 — second resistance; r3 — third resistance; r4-fourth resistor; r5-fifth resistor; r6-sixth resistance; r7 — seventh resistor; q1-triode; d1-diode; u2-optocouplers; c1 — first capacitance; c2-second capacitance.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

As described in the background art, in the current air conditioning operation, the electronic expansion valve may not be normally connected, which may not only affect the cooling and heating effects of the air conditioner, but also may damage the air conditioning system.

For example, fig. 1 shows an equivalent circuit diagram of an electronic expansion valve, and generally, the electronic expansion valve includes four phases, each of which has the same structure and includes a resistor, a driving power supply, and a connection port, and the driving power supply, the resistor, and the connection port are connected in sequence. Here, D1, D2, D3 and D4 shown in the figure respectively represent connection ports of each item.

Fig. 2 shows a schematic diagram of a driving chip of the electronic expansion valve, wherein the driving chip at least includes 4 pins, D1, D2, D3 and D4 respectively, connected to the electronic expansion valve. It can be understood that the pins of the driving chip are all electrically connected to the connection port of the electronic expansion valve, where the pin D1 is connected to the connection port D1, the pin D2 is connected to the connection port D2, and so on.

When the driving chip needs to control the electronic expansion valve to operate, a low level may be output to the corresponding pin, for example, when the phase corresponding to D1 that needs to control the electronic expansion valve is turned on, the pin D1 outputs a low level, and at this time, the phase corresponding to D1 of the electronic expansion valve is turned on by forming a loop through the driving power supply, the resistor and the connection port D1 in the electronic expansion valve.

However, in practical applications, it may happen that the electronic expansion valve is not connected. For example, if the pin D1 is not connected to the connection port D1, the electronic expansion valve D1 cannot be controlled to be turned on by the driving chip, which may not only affect the cooling and heating effects of the air conditioner, but also may damage the air conditioning system.

In view of the above, in order to solve the above problems, the present application provides an expansion valve connection detection circuit, which realizes detection of whether a driving chip and an electronic expansion valve are normally connected by arranging a connection detection module in the circuit.

The following is an exemplary description of the expansion valve connection detection circuit provided in the present application:

as an optional implementation manner, please refer to fig. 3, the expansion valve connection detection circuit 100 includes a main control chip 110, a control chip 120, and at least one connection detection module 130, wherein the main control chip 110 is electrically connected to a first pin of the control chip 120, the connection detection module 130 is electrically connected to a second pin of the control chip 120, the second pin of the control chip 120 is further used for being electrically connected to an electronic expansion valve 140, and the connection detection module 130 is further electrically connected to a first driving power supply and the main control chip 110.

Referring to fig. 4, the main control chip 110 is configured to send a control signal to the control chip 120, so as to control the working state of the electronic expansion valve 140 through the control chip 120. For example, when the control chip 120 receives the control signal from the main control chip 110, the second pin outputs a low level, so that the electronic expansion valve 140 works normally. In fig. 4, the main control chip 110 sends control signals to the control chip 120 through the pins P1, P2, P3, and P4.

The connection detection module 130 is configured to generate a first signal or a second signal according to a connection state between the second pin and the electronic expansion valve 140 when the control chip 120 is in the detection mode, where the first signal and the second signal are opposite signals, for example, the first signal may be a high level and the second signal is a low level, or the second signal may be a high level and the first signal is a low level. The main control chip 110 is further configured to determine a connection state between the control chip 120 and the electronic expansion valve 140 according to the received signal, for example, when the first signal is received, it is determined that the second pin is normally connected to the electronic expansion valve 140; when the second signal is received, it is determined that the second pin is abnormally connected to the electronic expansion valve 140. It is understood that the second pin described herein is normally connected to the electronic expansion valve 140, that is, the control chip 120 is normally connected to the electronic expansion valve 140.

It should be noted that, the connection between the main control chip 110 and the connection detection module 130 is not shown in fig. 4, and it should be understood that, in practical applications, the connection detection module 130 may be connected to pins of the main control chip 110, for example, the pins P7, P8, P9, and P10 of the main control chip 110 are used to connect to the connection detection module 130.

It should be noted that the detection mode described herein refers to a mode in which the second pin of the control chip 120 does not output a signal at this time, in other words, the second pin is in a floating state at this time.

By providing the connection detection module 130, it is possible to enable the main control chip 110 to determine the connection state between the control chip 120 and the electronic expansion valve 140.

The number of the connection detection modules 130 is not limited in the present application, and since the electronic expansion valve 140 includes four phases, the number of the second pins is 4, so that each second pin is connected to one phase of the electronic expansion valve 140.

On this basis, the number of the connection detection modules 130 may be 1, 2, 3, or 4. For example, the number of the connection detection modules 130 is 4, each second pin is electrically connected to one of the connection detection modules 130 and one of the electronic expansion valves 140, and each connection detection module 130 is electrically connected to the main control chip 110. Further, the main control chip 110 can recognize when any phase of the electronic expansion valve 140 is not connected to the control chip 120. Alternatively, the number of the connection detection modules 130 is 1, and when the electronic expansion valve 140 is not normally connected, the connection state of the electronic expansion valve 140 can be detected because the connection of 4 phases is normally not connected.

As an implementation manner, the connection detection module 130 may be formed by a transistor Q1 and a bias circuit, for example, please refer to fig. 5, where the connection detection module 130 includes a transistor Q1, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4, one end of the first resistor R1 is electrically connected to the second pin, the other end of the first resistor R1 is electrically connected to a base of the transistor Q1 and one end of the second resistor R2, the other end of the second resistor R2 is grounded, an emitter of the transistor Q1 is grounded, a collector of the transistor Q1 is electrically connected to one ends of the third resistor R3 and the fourth resistor R4, the other end of the third resistor R3 is electrically connected to the first driving power source VCC, the other end of the fourth resistor R4 is electrically connected to the main control chip 110, and the electronic expansion valve 140 is further connected to the second driving power source. On this basis, when the main control chip 110 receives the high level, it is determined that the second pin is abnormally connected with the electronic expansion valve 140; when the main control chip 110 receives a low level, it is determined that the second pin is normally connected to the electronic expansion valve 140. In fig. 5, the D1_ TEST port is connected to the main control chip 110.

As an implementation manner, the second driving power supply is +12V, and it can be understood that when the electronic expansion valve 140 is normally connected to the second pin, the signal D1 is 12V, the second driving power supply of the electronic expansion valve 140 drives the transistor Q1 to be turned on, and at this time, the first driving power supply, the third resistor R3 and the transistor Q1 form a loop, and the main control chip 110 receives a low level. When the electronic expansion valve 140 is not normally connected to the second pin, the signal D1 is 0V, and the transistor Q1 is turned off, and the main control chip 110 receives a high level.

In addition, since the first driving power source is 5V or 3.3V and the second driving power source is up to 12V, in order to protect the chip and the transistor Q1 and ensure that the transistor Q1 can be normally turned on and off, the connection detection module 130 further includes a diode D1, an anode of the diode D1 is electrically connected to a base of the transistor Q1, and a cathode of the diode D1 is electrically connected to the first driving power source. By providing the diode D1, when the voltage is too large, the current can flow to the first driving power source through the diode D1.

Optionally, in order to make the signal input to the main control chip 110 more stable, the connection detection module 130 further includes a first capacitor C1, one end of the first capacitor C1 is electrically connected to the fourth resistor R4, and the other end of the first capacitor C1 is grounded. By providing the first capacitor C1, an effect of filtering a signal can be achieved.

As another optional implementation manner of the present application, please refer to fig. 6, the connection detection module 130 may also be implemented by an optocoupler U2, the connection detection module 130 includes an optocoupler U2, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7, the optocoupler U2 includes a light emitting diode D1 and a light receiving transistor Q1, one end of the fifth resistor R5 is electrically connected to the second pin, the other end of the fifth resistor R5 is electrically connected to an anode of the light emitting diode D1, a cathode of the light emitting diode D1 is grounded, a collector of the light receiving transistor Q1 is electrically connected to the first driving power supply, an emitter of the light receiving transistor Q1 is electrically connected to one ends of the sixth resistor R6 and the seventh resistor R7, the other end of the sixth resistor R6 is grounded, and the other end of the seventh resistor R7 is electrically connected to the main control. When the main control chip 110 receives a high level, it is determined that the second pin is normally connected to the electronic expansion valve 140, and when the main control chip 110 receives a low level, it is determined that the second pin is abnormally connected to the electronic expansion valve 140.

Different from the scheme for realizing detection through the triode Q1, when the electronic expansion valve 140 is normally connected with the control chip 120, 12V is input at the D1 port, at this time, the optocoupler U2 is turned on, and the main control chip 110 can receive a high-level signal. When the electronic expansion valve 140 is not normally connected to the control chip 120, 0V is input to the D1 port, and at this time, the optocoupler U2 is not turned on, and the main control chip 110 can receive a low level signal.

Similarly, in order to stabilize the signal input to the main control chip 110, the connection detection module 130 further includes a second capacitor C2, one end of the second capacitor C2 is electrically connected to the other end of the seventh resistor R7, and the other end of the second capacitor C2 is grounded. The second capacitor C2 also achieves a filtering effect.

In summary, the expansion valve connection detection circuit 100 provided in the present application, by adding the connection detection module 130, can detect whether the electronic expansion valve 140 is normally connected on the premise that the control chip 120 normally controls the electronic expansion valve 140 to operate.

Based on the foregoing implementation manner, an embodiment of the present application further provides an air conditioner, which includes the above expansion valve connection detection circuit 100.

Based on the foregoing implementation manner, an embodiment of the present application further provides an expansion valve connection detection method, which is applied to the main control chip 110 of the expansion valve connection detection circuit 100, please refer to fig. 7, and the method includes:

s102, the control chip 120 is controlled to enter the detection mode.

S104, determining the connection state of the second pin and the electronic expansion valve 140 according to the received signal sent by the connection detection module 130; when the first signal is received, it is determined that the second pin is normally connected with the electronic expansion valve 140; when a second signal is received, it is determined that the second pin is abnormally connected with the electronic expansion valve 140, wherein the first signal and the second signal are opposite signals.

The control chip 120 entering the detection mode means that the main control chip 110 controls the corresponding disconnection of the electronic expansion valve 140, that is, the second pin corresponding to the control chip 120 is suspended, and the voltage of the second pin at this time is detected.

When the voltage of the second pin is 12V at this time, it is determined that the electronic expansion valve 140 is normally connected; when the voltage of the second pin is 0V at this time, it is determined that the electronic expansion valve 140 is not normally connected.

The judgment criteria for whether the electronic expansion valve 140 is normally connected are as follows:

in one case, when a high level is received, it is determined that the second pin is abnormally connected to the electronic expansion valve 140; when the low level is received, it is determined that the second pin is normally connected to the electronic expansion valve 140. In another case, when the high level is received, it is determined that the second pin is normally connected to the electronic expansion valve 140; when receiving the low level, determining that the connection between the second pin and the electronic expansion valve 140 is abnormal may be determined according to a specific circuit of the connection detection module 130.

Moreover, as an implementation manner, in order to ensure the test accuracy, the connection state of the electronic expansion valve 140 may be determined by adding filtering, delaying or multiple judgments. For example, after the first determination, the second determination is performed after 100ms until a certain number of determinations are reached, and the connection state of the electronic expansion valve 140 is not determined until each determination is the same.

Based on the foregoing implementation manner, an embodiment of the present application further provides another expansion valve connection detection method, where the method is applied to a main control chip 110 of an expansion valve connection detection circuit 100, where the expansion valve connection detection circuit 100 further includes a control chip 120 and at least one connection detection module 130, the main control chip 110 is electrically connected to a first pin of the control chip 120, the connection detection module 130 is electrically connected to a second pin of the control chip 120, the second pin of the control chip 120 is further used for being electrically connected to an electronic expansion valve 140, and the connection detection module 130 is further electrically connected to a first driving power supply and the main control chip 110; referring to fig. 8, the method includes:

s202, acquiring the proportion of a first signal and a second signal, which are sent by the connection detection module 130 and received in a fixed period of the operation of the electronic expansion valve 140; the first signal and the second signal are opposite signals.

S204, determining the connection state of the second pin and the electronic expansion valve 140 according to the proportion and the preset proportion.

As an implementation manner, the fixed period provided by the present application may be 8T, and fig. 5 shows an operation timing diagram of the electronic expansion valve 140, and as can be seen from the timing diagram, the duty ratio of the turn-off is fixed 5/8 for each phase in the fixed period 8T when the electronic expansion valve 140 operates. And accumulating the detected 12V state with 8T as a fixed detection period, comparing the accumulated time with 5T, and if the accumulated time is 5T + an error value (which can be +/-T/2), determining that the connection is normal, otherwise, determining that the connection is abnormal. If the electronic expansion valve 140 is not operated and is always in the off state, the connection can be determined to be normal only if the accumulated time is 8T, otherwise, the connection is determined to be abnormal.

Thus, for any phase of the electronic expansion valve 140, the ratio of the first signal to the second signal is 3: 5, whether the electronic expansion valve 140 is normally connected to the second pin of the control signal can be determined according to whether the ratio is satisfied.

In summary, the present application provides an expansion valve connection detection circuit, a detection method and an air conditioner, wherein the expansion valve connection detection circuit includes a main control chip, a control chip and at least one connection detection module, the main control chip is electrically connected with a first pin of the control chip, the connection detection module is electrically connected with a second pin of the control chip, the second pin of the control chip is also used for being electrically connected with an electronic expansion valve, and the connection detection module is also electrically connected with a first driving power supply and the main control chip; the main control chip is used for sending a control signal to the control chip so as to control the working state of the electronic expansion valve through the control chip; the connection detection module is used for generating a first signal or a second signal according to the connection state of the second pin and the electronic expansion valve when the control chip is in a detection mode, wherein the first signal and the second signal are opposite signals; the main control chip is also used for determining that the second pin is normally connected with the electronic expansion valve when receiving the first signal; and when the second signal is received, determining that the second pin is abnormally connected with the electronic expansion valve. Because the connection detection module is arranged in the expansion valve connection detection circuit provided by the application, whether the electronic expansion valve is normally connected or not can be detected by utilizing the connection detection module. Meanwhile, the connection detection module is connected with the second pin, so that when the main control chip controls the working state of the electronic expansion valve, the work of the electronic expansion valve cannot be influenced.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.