Protection circuit and air conditioner

Abstract

The invention discloses a protection circuit and an air conditioner. The protection circuit comprises a first terminal and a second terminal which serve as input ends, a third terminal and a fourth terminal which serve as output ends, a voltage detection module and a control circuit. Wherein the first terminal is connected with a first power line, and the second terminal is connected with a second power line; the third terminal is electrically connected with the first terminal, and the fourth terminal is electrically connected with the second terminal; the input end of the voltage detection module is connected with the first terminal and the second terminal, and the voltage detection module is used for obtaining a line voltage sampling value between the first power line and the second power line, generating a reference voltage used for being compared with the line voltage sampling value, and generating a comparison result of the line voltage sampling value and the reference voltage; the input end of the control circuit is connected with the output end of the voltage detection module, and the control circuit is used for controlling the on-off state between the third terminal and the first terminal based on the comparison result. Therefore, the protection of a full-hardware circuit on the device is realized, the participation of software is not needed, and the circuit cost is reduced.

Description

Technical Field

[0001] The present application relates to the field of circuit design, and in particular to a protection circuit and an air conditioner. Background Art

[0002] In the related art, there are three-phase air conditioners of the three-phase power supply type. The circuit structure of the three-phase power supply usually adopts a three-phase four-wire system, that is, it includes four power lines, including three live wires and one neutral wire. In order to avoid the misconnection of the live and neutral wires of the three-phase air conditioner, which leads to damage to related components in the air conditioner and causes the air conditioner to fail to work properly, a solution can be adopted to improve the voltage resistance of the components and software detection to prevent component damage when the live and neutral wires are connected incorrectly.

[0003] However, adopting the above solution and using devices with higher withstand voltage will greatly increase the cost of related devices. In addition, when the power supply is normally wired and the air conditioner is normally used, the device does not need a higher withstand voltage performance, which also causes a waste of device resources. Summary of the invention

[0004] In view of this, an embodiment of the present application provides a protection circuit and an air conditioner, which are intended to protect the air conditioner from damage when it is connected incorrectly and reduce circuit costs.

[0005] The technical solution of the embodiment of the present application is implemented as follows:

[0006] In a first aspect, an embodiment of the present application provides a protection circuit, the protection circuit comprising:

[0007] A first terminal and a second terminal as input terminals, the first terminal being connected to a first power line, and the second terminal being connected to a second power line;

[0008] A third terminal and a fourth terminal as output terminals, the third terminal being electrically connected to the first terminal, and the fourth terminal being electrically connected to the second terminal;

[0009] a voltage detection module, wherein an input end of the voltage detection module is connected to the first terminal and the second terminal, and is used to obtain a line voltage sampling value between the first power line and the second power line, generate a reference voltage for comparison with the line voltage sampling value, and generate a comparison result between the line voltage sampling value and the reference voltage;

[0010] A control circuit, wherein an input end of the control circuit is connected to an output end of the voltage detection module, and is used to control an on-off state between the third terminal and the first terminal based on the comparison result.

[0011] In some embodiments, the voltage detection module includes:

[0012] a reference voltage conversion module, wherein an input end of the reference voltage conversion module is connected to the first terminal and the second terminal, and is used to convert a line voltage between the first power line and the second power line into a reference voltage;

[0013] A line voltage sampling circuit, wherein the input end of the line voltage sampling circuit is respectively connected to the input end of the reference voltage conversion module and the second terminal, and is used to obtain the line voltage sampling value;

[0014] A voltage comparison circuit, wherein the input end of the voltage comparison circuit is connected to the output end of the reference voltage conversion module and the output end of the line voltage sampling circuit, and the output end of the voltage comparison circuit is connected to the input end of the control circuit, for generating a comparison result between the line voltage sampling value and the reference voltage.

[0015] In some embodiments, the reference voltage conversion module includes:

[0016] a rectifier diode, wherein an input end of the rectifier diode is connected to the first terminal, and an output end of the rectifier diode is connected to an input end of the line voltage sampling circuit, and is used to rectify the line voltage between the first power line and the second power line;

[0017] a voltage stabilizing circuit, the input end of which is connected to the output end of the rectifier diode, and is used to stabilize the line voltage between the first power line and the second power line after rectification to generate a regulated voltage;

[0018] a fifth terminal connected to an output end of the voltage stabilizing circuit;

[0019] A reference voltage conversion circuit, wherein the input end of the reference voltage conversion circuit is connected to the fifth terminal and is used to convert the regulated voltage to the reference voltage, and the output end of the reference voltage conversion circuit is connected to the input end of the voltage comparison circuit.

[0020] In some embodiments, the voltage comparison circuit includes:

[0021] A comparator, wherein the input end of the comparator is respectively connected to the output end of the reference voltage conversion module and the line voltage sampling circuit, and the output end of the comparator is connected to the input end of the control circuit, for determining whether the reference voltage is less than or equal to the line voltage sampling value, and sending the detection result to the control circuit.

[0022] In some embodiments, the voltage stabilization circuit includes:

[0023] a first resistor, wherein an input end of the first resistor is connected to an output end of the rectifier diode;

[0024] A voltage zener diode, an input end of the voltage zener diode is connected to an output end of the first resistor;

[0025] A first capacitor, wherein an input end of the first capacitor is connected to the output end of the voltage stabilizing diode, and an output end of the first capacitor is connected to the fifth terminal.

[0026] In some embodiments, the reference voltage conversion circuit includes:

[0027] A second resistor, wherein an input end of the second resistor is connected to the fifth terminal, and an output end of the second resistor is connected to an input end of the voltage comparison circuit.

[0028] In some embodiments, the line voltage sampling circuit includes:

[0029] a third resistor, the third resistor being connected to the output end of the rectifier diode and the second terminal respectively;

[0030] A second capacitor, wherein an input terminal of the second capacitor is connected to an output terminal of the third resistor, and an output terminal of the second capacitor is connected to an input terminal of the voltage comparison circuit.

[0031] In some embodiments, the control circuit comprises:

[0032] a fourth resistor, wherein an input end of the fourth resistor is connected to an output end of the voltage detection module;

[0033] A transistor, an input end of the transistor is connected to an output end of the fourth resistor;

[0034] A relay, wherein the input end of the relay is connected to the output end of the transistor, and the output end of the relay is connected to the third terminal.

[0035] In a second aspect, an embodiment of the present application provides an air conditioner, comprising: a protection circuit and a multi-phase power supply network as described in the first aspect above, wherein the protection circuit is connected to the multi-phase power supply network, and the multi-phase power supply network is a three-phase four-wire power supply network.

[0036] In some embodiments, the air conditioner further comprises:

[0037] a single-phase load circuit, wherein an input end of the single-phase load circuit is connected to the third terminal and the fourth terminal respectively;

[0038] A fan load module, the input end of the fan load module is connected to the output end of the single-phase load circuit;

[0039] A switching power supply load module, wherein the input end of the switching power supply load module is connected to the output end of the single-phase load circuit.

[0040] In some embodiments, the air conditioner further comprises:

[0041] An AC load module, wherein an input end of the AC load module is connected to the third terminal and the fourth terminal respectively.

[0042] In some embodiments, the air conditioner further comprises:

[0043] A multi-phase load circuit, the input end of which is connected to the three-phase four-wire power supply network;

[0044] A compressor load module, wherein an input end of the compressor load module is connected to an output end of the multi-phase load circuit.

[0045] The technical solution provided by the embodiment of the present application provides a protection circuit, which includes: a first terminal and a second terminal as input terminals, a third terminal and a fourth terminal as output terminals, a voltage detection module and a control circuit. Among them, the first terminal is connected to the first power line, and the second terminal is connected to the second power line; the third terminal is electrically connected to the first terminal, and the fourth terminal is electrically connected to the second terminal; the input terminal of the voltage detection module is connected to the first terminal and the second terminal, and is used to obtain the line voltage sampling value between the first power line and the second power line, generate a reference voltage for comparison with the line voltage sampling value, and generate a comparison result between the line voltage sampling value and the reference voltage; the input terminal of the control circuit is connected to the output terminal of the voltage detection module, and is used to control the on-off state between the third terminal and the first terminal based on the comparison result. In this way, the protection of the device is realized by using a full hardware circuit, without the participation of software, with strong versatility, and at the same time reducing the cost of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a structural schematic diagram of a power supply circuit of a three-phase air conditioner in the related art;

[0047] Figure 2 It is a structural schematic diagram of a protection scheme for misconnection of zero and live wires of a three-phase air conditioner in the related art;

[0048] Figure 3 A schematic diagram of the structure of a protection circuit provided in an embodiment of the present application;

[0049] Figure 4 A schematic diagram of the circuit structure of a protection circuit provided in an embodiment of the present application;

[0050] Figure 5 This is a structural schematic diagram of a protection circuit for a three-phase air conditioner in an application example of the present application;

[0051] Figure 6 Schematic diagram of the circuit structure of a protection circuit in an application example of the present application. DETAILED DESCRIPTION

[0052] The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0054] In the related art, refer to Figure 1 , Figure 1 The present invention is a schematic diagram of the structure of the power supply circuit of a three-phase air conditioner in the related art. The power supply circuit includes four power lines, including three live wires A, B and C, and one neutral wire N, and contains two main power supply circuits. Power supply circuit 1: the three live wires A, B and C are used as the power supply for the compressor load after passing through the rectifier and filter circuit. The rectifier and filter circuit includes 6 diodes (D1, D2, D3, D4, D5 and D6) and two electrolytic capacitors (C1 and C2); Power supply circuit 2: one live wire C and one neutral wire N are used as the power supply for the AC load, and at the same time, they are used as the power supply for the switch power supply load and the fan load through the rectifier and filter circuit. The rectifier and filter circuit includes 4 diodes (D7, D8, D9 and D10) and an electrolytic capacitor (C3).

[0055] When the zero and live wires of the three-phase air conditioner are connected incorrectly, the input power of power circuit 2 becomes two live wires, which will increase the supply voltage of the AC load in power circuit 2 and increase the bus voltage after rectification. This may cause Figure 1 The components shown, such as the AC load, electrolytic capacitor C3 and the chip IC1 of the switching power supply, are damaged due to overvoltage.

[0056] In order to solve the problem of device damage caused by incorrect connection of the neutral and live wires of the power supply, refer to Figure 2 , Figure 2 This is a structural diagram of a three-phase air conditioner neutral and live wire connection error protection scheme. The solutions in the related art are:

[0057] 1. Electrolytic capacitor: C3 is connected in series, or an electrolytic capacitor with a higher withstand voltage is used;

[0058] like Figure 2 As shown, on the basis of the electrolytic capacitor C3-1, another electrolytic capacitor C3-2 is added and connected in series therewith.

[0059] 2. Switching power supply chip: add overvoltage protection circuit, or use power supply chip with higher voltage resistance;

[0060] like Figure 2As shown, an overvoltage protection circuit is added at both ends of the switching power supply chip IC1 of the switching power supply load.

[0061] 3. AC load: When the voltage of power circuit 2 is too high, the AC load is turned off through software detection.

[0062] like Figure 2 As shown, a microcontroller MCU is set at one end of the AC load, and the AC load is turned off when the voltage of the power supply circuit 2 is too high based on the MCU software detection.

[0063] However, the above solution mainly prevents damage to components when the neutral and live wires are connected incorrectly by improving the withstand voltage of circuit components and adding software detection. However, the increased withstand voltage will lead to a significant increase in the cost of related components in the circuit. However, when the power supply is normally connected and the air conditioner is used normally, the components do not need such a high withstand voltage, which is also a waste of resources.

[0064] Based on this, the embodiment of the present application provides a protection circuit, such as Figure 3 As shown, the protection circuit includes:

[0065] A first terminal P1 and a second terminal P2 as input terminals, the first terminal P1 is connected to the first power line L1, and the second terminal P2 is connected to the second power line L2;

[0066] A third terminal P3 and a fourth terminal P4 as output terminals, the third terminal P3 is electrically connected to the first terminal P1, and the fourth terminal P4 is electrically connected to the second terminal P2;

[0067] A voltage detection module, wherein an input end of the voltage detection module is connected to a first terminal P1 and a second terminal P2, and is used to obtain a line voltage sampling value V2 between a first power line L1 and a second power line L2, generate a reference voltage V1 for comparison with the line voltage sampling value V2, and generate a comparison result between the line voltage sampling value V2 and the reference voltage V1;

[0068] The control circuit has an input end connected to the output end of the voltage detection module, and is used to control the on-off state between the third terminal P3 and the first terminal P1 based on the comparison result.

[0069] Here, the power line is used to supply power to the protection circuit. The input end and the output end of the protection circuit are connected to the first power line L1 and the second power line L2. Exemplarily, the first power line L1 includes a first power line L11 located on the input side of the protection circuit and a first power line L12 located on the output side of the protection circuit. As the first terminal P1 and the second terminal P2 of the input end of the protection circuit, the first terminal P1 is respectively connected to the first power line L11 and the voltage detection module located on the input side of the protection circuit, and the first terminal P1 inputs the voltage on the first power line L11 to the input end of the voltage detection module. The second terminal P2 is respectively connected to the second power line L2 and the voltage detection module, and the second terminal P2 inputs the voltage on the second power line L2 to the input end of the voltage detection module. In order to ensure that the device can be protected from damage when the neutral line and the live line are misconnected, the first power line and the second power line can be a live line or a neutral line.

[0070] Here, the third terminal P3 and the fourth terminal P4 are terminals serving as output ends of the protection circuit. The third terminal P3 is located on the first power line L12 at the output side of the protection circuit. The third terminal P3 is electrically connected to the first terminal P1 , and the fourth terminal P4 is electrically connected to the second terminal P2 .

[0071] Here, the input end of the voltage detection module is connected to the first terminal P1 and the second terminal P2, that is, the line voltage from the first power line L1 and the line voltage from the second power line L2 are input to the input end of the voltage detection module, and the voltage detection module can obtain the line voltage sampling value V2 between the first power line L1 and the second power line L2. The voltage detection module is also used to generate a reference voltage V1 for comparison with the line voltage sampling value V2, and to generate a comparison result between the line voltage sampling value V2 and the reference voltage.

[0072] Exemplarily, the line voltage between the first power line L1 and the second power line L2 is 220VAC, and its corresponding line voltage sampling value V2 is 1.5V. The line voltage is 300VAC and the corresponding line voltage sampling value V2 is 2.0V. The line voltage is 380VAC and the corresponding line voltage sampling value V2 is 2.5V. AC here refers to alternating current.

[0073] Here, the input end of the control circuit is connected to the output end of the voltage detection module, and the output end of the control circuit is connected to the third terminal P3, which is used to control the on-off state between the third terminal P3 and the first terminal P1 based on the comparison result. The comparison result is used to indicate whether the circuit is connected incorrectly, such as the live wire and the neutral wire are connected reversely, and timely adjustment is required. Based on the comparison result, the on-off state of the third terminal P3 and the first terminal P1 is controlled.

[0074] In this way, through the above circuit structure, when the circuit is misconnected, the protection of the circuit components can be automatically achieved by utilizing the protection of the components by the full hardware circuit, without the need for software participation, with strong versatility and reducing the cost of the circuit.

[0075] In some embodiments, the voltage detection module includes:

[0076] A reference voltage conversion module, the input end of which is connected to the first terminal P1 and the second terminal P2, and is used to convert the line voltage between the first power line L1 and the second power line L2 into a reference voltage V1;

[0077] A line voltage sampling circuit, the input end of which is respectively connected to the input end of the reference voltage V1 conversion module and the second terminal P2, for obtaining a line voltage sampling value V2;

[0078] A voltage comparison circuit, wherein the input end of the voltage comparison circuit is connected to the output end of the reference voltage conversion module and the output end of the line voltage sampling circuit, and the output end of the voltage comparison circuit is connected to the input end of the control circuit, for generating a comparison result between the line voltage sampling value V2 and the reference voltage V1.

[0079] Here, the input end of the reference voltage conversion module is connected to the first terminal P1 and the second terminal P2. Since the first terminal P1 is connected to the first power line L1 and the second terminal P2 is connected to the second power line L2, the reference voltage conversion module can obtain the line voltage on the first power line L1 and the line voltage on the second power line L2, and convert the line voltage between the first power line L1 and the second power line into a reference voltage V1. The reference voltage V1 here can be a threshold voltage.

[0080] Here, the input end of the line voltage sampling circuit is respectively connected to the input end of the reference voltage conversion module and the second terminal P2. The line voltage sampling circuit can obtain the line voltage on the first power line L1 based on the reference voltage conversion module, and obtain the line voltage on the second power line L2 based on the second terminal P2. That is, the line voltage sampling circuit is used to obtain the line voltage sampling value V2 between the first power line L1 and the second power line L2. When the first power line L1 and the second power line L2 are both live wires, the line voltage between the live wires is 380V. When the first power line L1 is the live wire and the second power line L2 is the neutral wire, the line voltage between the live wire and the neutral wire is 220V. Exemplarily, the reference voltage can be a threshold voltage, and the threshold voltage can be a voltage value passing through the line voltage sampling unit when the input voltage is about 300VAC, where AC refers to alternating current.

[0081] Here, the input end of the voltage comparison circuit is connected to the output end of the reference voltage conversion module and the output end of the line voltage sampling circuit. The voltage comparison circuit generates a comparison result of the line voltage sampling value V2 between the first power line L1 and the second power line L2 and the reference voltage V1 based on the line voltage sampling value V2 between the first power line L1 and the second power line L2.

[0082] Exemplarily, the comparison result can be a high-level signal or a low-level signal. For example, the high-level signal is used to indicate that the connection of the current circuit is normal, and the low-level signal is used to indicate that the current circuit is misconnected. The output end of the voltage comparison circuit is connected to the input end of the control circuit. The voltage comparison circuit inputs the high and low-level signals to the control circuit. The control circuit uses the high-level signal or the low-level signal to control the on-off state between the third terminal P3 and the first terminal P1. For example, when a low-level signal is received, the circuit is misconnected at this time, and the control circuit controls the disconnection of the third terminal P3 and the first terminal P1. In this way, the protection of the circuit components is automatically realized, and the cost of the circuit is reduced.

[0083] In some embodiments, reference Figure 3 and Figure 4 , the reference voltage conversion module includes:

[0084] A rectifier diode D, an input end of the rectifier diode D is connected to the first terminal P1, and an output end of the rectifier diode D is connected to an input end of the line voltage sampling circuit, for rectifying the line voltage between the first power line L1 and the second power line L2;

[0085] A voltage stabilizing circuit, the input end of which is connected to the output end of the rectifier diode D, for stabilizing the line voltage between the rectified first power line L1 and the second power line L2 to generate a regulated voltage;

[0086] A fifth terminal connected to the output end of the voltage stabilizing circuit;

[0087] The reference voltage conversion circuit has an input end connected to the fifth terminal and is used to convert the regulated voltage to the reference voltage V1 , and an output end of the reference voltage conversion circuit is connected to the input end of the voltage comparison circuit.

[0088] Here, the rectifier diode D is connected to the first terminal P1 and the input end of the line voltage sampling circuit, and the input end of the line voltage sampling circuit is connected to the second terminal, so that the rectifier diode D can obtain the line voltage of the first power line L1 and the second power line L2, and output the line voltage between the first power line L1 and the second power line L2 after half-wave rectification. The input end of the voltage stabilization circuit is connected to the output end of the rectifier diode D, and the line voltage between the first power line L1 and the second power line L2 rectified by the rectifier diode is stabilized to generate a regulated voltage output.

[0089] The regulated voltage generated here is a power supply voltage VDD, which is used to power the subsequent circuit. The voltage stabilizing circuit may include a voltage regulator. Here, the VDD voltage output by the voltage stabilizing circuit is not the voltage corresponding to the line voltage between the first terminal P1 and the second terminal P2 after rectification, but a required stable power supply voltage VDD obtained by clamping the line voltage of the first power line L1 and the second power line L2 through a voltage regulator tube after rectification, for use by the subsequent circuit. Exemplarily, the control circuit requires a 12V DC voltage, and a 12V voltage regulator tube can be selected here, and VDD is 12V. Regardless of whether the input voltage is 220V or 380V, this voltage remains unchanged.

[0090] Here, the fifth terminal includes a terminal P51 and a terminal P52 , the fifth terminal is connected to the output end of the voltage stabilizing circuit, and both ends of the output end of the voltage stabilizing circuit are connected to the terminal P51 and the terminal P52 .

[0091] Here, the input end of the reference voltage conversion circuit is connected to the fifth terminal, that is, the two ends of the input end of the reference voltage conversion circuit are connected to terminal P51 and terminal P52, which is used to convert the regulated voltage, that is, the required power supply voltage VDD, to the reference voltage V1 and output it to the voltage comparison circuit.

[0092] Exemplarily, the reference voltage V1 is set according to the required protection threshold voltage, which can be obtained by dividing the power supply voltage VDD. For example: the reference voltage V1 is set to 2.0V, that is, the corresponding line voltage during protection is 300VAC. When the line voltage exceeds 300VAC, the line voltage sampling value V2 will exceed the set reference voltage V1 by 2.0V, which will trigger the protection disconnect switch.

[0093] In some embodiments, the voltage comparison circuit includes:

[0094] A comparator, wherein the input end of the comparator is respectively connected to the output end of the reference voltage conversion module and the line voltage sampling circuit, and the output end of the comparator is connected to the input end of the control circuit, for determining whether the reference voltage V1 is less than or equal to the line voltage sampling value V2 between the first power line L1 and the second power line L2, and sending the detection result to the control circuit.

[0095] Here, the input terminal of the comparator is connected to the output terminals of the reference voltage conversion module and the line voltage sampling circuit, and is used to obtain the reference voltage V1 output by the reference voltage conversion module and the line voltage sampling value V2 between the first power line L1 and the second power line L2 output by the line voltage sampling circuit. Based on the reference voltage V1 and the line voltage sampling value V2, it is determined whether the reference voltage V1 is less than or equal to the line voltage sampling value V2, and the detection result is sent to the control circuit. Exemplarily, when the comparator determines that V1 > V2, a high level is output to the control circuit; when V1 < V2, a low level is output to the control circuit.

[0096] In some embodiments, referring to Figure 4 , the voltage stabilizing circuit includes:

[0097] A first resistor, the input terminal of the first resistor is connected to the output terminal of the rectifier diode D;

[0098] A voltage stabilizing diode DZ1, the input terminal of the voltage stabilizing diode is connected to the output terminal of the first resistor;

[0099] A first capacitor E1, the input terminal of the first capacitor E1 is connected to the output terminal of the voltage stabilizing diode DZ1, and the output terminal of the first capacitor E1 is connected to the fifth terminal.

[0100] Here, the first resistor includes resistor R1 and resistor R2, and resistor R1 and R2 are used for voltage division. The voltage stabilizing diode DZ1 is connected to the output terminal of the first resistor, the voltage stabilizing diode DZ1 is used for voltage stabilization, the input terminal of the first capacitor E1 is connected to the output terminal of the voltage stabilizing diode DZ1, and the capacitor E1 filters to obtain the required power supply voltage VDD after voltage stabilization

[0101] In some embodiments, referring to Figure 4 , the reference voltage conversion circuit includes:

[0102] A second resistor, the input terminal of the second resistor is connected to the fifth terminal, and the output terminal of the second resistor is connected to the input terminal of the voltage comparison circuit.

[0103] Here, the second resistor includes resistor R5 and resistor R6, and resistor R5 and R6 are used for voltage division. The input terminal of the second resistor is connected to the fifth terminal, and the power supply voltage VDD generated after voltage stabilization is divided by resistor R5 and R6 to obtain the reference voltage V1.

[0104] In some embodiments, the line voltage sampling circuit includes:

[0105] A third resistor, the input terminal of the third resistor is respectively connected to the output terminal of the rectifier diode D and the second terminal;

[0106] A second capacitor E2, the input terminal of the second capacitor E2 is connected to the output terminal of the third resistor, and the output terminal of the second capacitor E2 is connected to the input terminal of the voltage comparison circuit.

[0107] Here, the third resistor includes a resistor R3 and a resistor R4, and the resistor R3 and the resistor R4 are used for voltage division. The input end of the third resistor is connected to the output end of the rectifier diode D, and the line voltage of the first power line after rectification by the rectifier diode can be obtained. The input end of the third resistor is connected to the second terminal, and the line voltage value of the second power line can be obtained. The third resistor is used for voltage division, and the second capacitor E2 is filtered to obtain the corresponding line voltage sampling value V2 between the first power line L1 and the second power line L2.

[0108] In some embodiments, the control circuit comprises:

[0109] a fourth resistor, wherein an input end of the fourth resistor is connected to an output end of the voltage detection module;

[0110] A transistor Q1, wherein an input end of the transistor Q1 is connected to an output end of a fourth resistor;

[0111] Relay RY1, the input end of the relay RY1 is connected to the output end of the transistor Q1, and the output end of the relay RY1 is connected to the third terminal.

[0112] Here, the fourth resistor includes a resistor R7 and a resistor R8. The input end of the fourth resistor is connected to the output end of the voltage detection module. The input end of the transistor Q1 is connected to the output end of the fourth resistor, the input end of the relay RY1 is connected to the output end of the transistor Q1, and the output end of the relay RY1 is connected to the third terminal. The relay RY1 includes a switch S1. When the transistor Q1 is turned on, the switch S1 of the control relay RY1 is pulled in to supply power to the subsequent stage; when the transistor Q1 is not turned on, the switch S1 of the control relay RY1 is turned off, and the subsequent circuit is not powered, thereby protecting the subsequent devices from damage.

[0113] An embodiment of the present application further provides an air conditioner, comprising: a protection circuit, the protection circuit being connected to a multi-phase power supply network, and the multi-phase power supply network is a three-phase four-wire power supply network.

[0114] Here, the air conditioner can be a cooling-only air conditioner or a cooling-and-heating dual-purpose air conditioner. The air conditioner can be a wall-mounted air conditioner, a cabinet air conditioner, a window air conditioner, or a ceiling air conditioner, etc. The embodiments of the present application do not make specific limitations on this.

[0115] Here, the multi-phase power supply network includes multiple power lines, including at least one live line and one neutral line. The three-phase four-wire power supply network includes three live lines and one neutral line. Here, the protection circuit is connected to the multi-phase power supply network to detect whether the live and neutral lines in the multi-phase power supply network are misconnected. When a misconnection is detected, the third terminal is automatically disconnected from the first terminal to protect the subsequent devices from damage. When no misconnection is detected, the multi-phase power supply network normally supplies power for subsequent operations.

[0116] In some embodiments, the air conditioner further comprises:

[0117] A single-phase load circuit, wherein an input end of the single-phase load circuit is respectively connected to the third terminal P3 and the fourth terminal P4;

[0118] A fan load module, the input end of the fan load module is connected to the output end of the single-phase load circuit;

[0119] A switching power supply load module, wherein the input end of the switching power supply load module is connected to the output end of the single-phase load circuit.

[0120] Here, the input end of the single-phase load circuit is connected to the third terminal P3 and the fourth terminal P4, and is used to rectify and filter the input voltage before outputting it. The single-phase load circuit includes a single-phase rectifier bridge and a filter capacitor.

[0121] Here, the input end of the fan load module is connected to the output end of the single-phase load circuit; the input end of the switch power supply load module is connected to the output end of the single-phase load circuit. The voltage output after rectification and filtering of the single-phase load circuit is supplied to the fan load module and the switch power supply load module.

[0122] In some embodiments, the air conditioner further comprises:

[0123] The AC load module has an input end connected to the third terminal P3 and the fourth terminal P4 respectively.

[0124] Here, the input end of the AC load module can be directly connected to the third terminal P3 and the fourth terminal P4 respectively, and no rectification and filtering are required. The AC load module here includes a valve body.

[0125] In some embodiments, the air conditioner further comprises:

[0126] A multi-phase load circuit, wherein an input end of the multi-phase load circuit is connected to a three-phase four-wire power supply network;

[0127] A compressor load module, wherein an input end of the compressor load module is connected to an output end of the multi-phase load circuit.

[0128] Here, the input end of the multi-phase load circuit is connected to the three-phase four-wire power supply network, and the multi-phase load circuit includes a multi-phase rectifier bridge and a filter capacitor, which is used to rectify and filter the voltage output by the three-phase four-wire power supply network before outputting it. The output end of the multi-phase load circuit is connected to the input end of the compressor load module, and the rectified and filtered voltage is supplied to the compressor load module to ensure its normal operation.

[0129] The following is a detailed description with reference to an application example.

[0130] This application example proposes a protection circuit for the misconnection of the neutral and live wires of a three-phase air conditioner. That is, this application example is applied to a three-phase four-wire power supply network. Figure 5 This is a schematic diagram of the protection circuit of a three-phase air conditioner. Figure 5 The three-phase air conditioner includes a three-phase four-wire power supply network and a protection circuit. The three-phase four-wire power supply network includes three live wires A, B and C and one neutral wire N. The protection circuit is set Figure 5 The input end of the power supply circuit 2 is connected to the three-phase four-wire power supply network. The output end of the protection circuit is connected to the input end of the power supply circuit 2, and the input end of the protection circuit is connected to the live wire C and the neutral wire N.

[0131] For the live wire C, the live wire located at the input side of the protection circuit is C1, and the live wire located at the output side of the protection circuit is C2. The protection circuit includes: a first terminal P1 and a second terminal P2 as input terminals, the first terminal P1 is connected to the live wire C1, the second terminal P2 is connected to the neutral wire N, a third terminal P3 and a fourth terminal P4 as output terminals, the third terminal P3 is electrically connected to the first terminal P1, and the fourth terminal P4 is electrically connected to the second terminal P2.

[0132] The air conditioner also includes a single-phase load circuit, a fan load module, a switch power supply load module, an AC load module, a three-phase load circuit, and a compressor load module.

[0133] The input end of the three-phase load circuit is connected to the three-phase four-wire power supply network, and the input end of the three-phase load circuit is respectively connected to the three live wires A, B and C, and the input end of the compressor load module is connected to the output end of the three-phase load circuit. The three-phase load circuit is used to rectify and filter the input voltage and output it, including a three-phase rectifier bridge and filter capacitors C1 and C2. Diodes D1, D2, D3, D4, D5 and D6 are connected to each other to form a three-phase rectifier bridge.

[0134] The input end of the single-phase load circuit is connected to the third terminal P3 and the fourth terminal P4 respectively; the input end of the fan load module is connected to the output end of the single-phase load circuit; the input end of the switch power supply load module is connected to the output end of the single-phase load circuit. The input end of the AC load module is connected to the third terminal P3 and the fourth terminal P4 respectively. The single-phase load circuit is used to rectify and filter the input voltage and then output it, including a single-phase rectifier bridge and a filter capacitor C3. Diodes D7, D8, D9 and D10 are connected to each other to form a single-phase rectifier bridge.

[0135] This application example uses hardware to automatically identify and determine the power supply. When the neutral and live wires are connected incorrectly and the input voltage exceeds the threshold range, the power supply of power supply circuit 2 can be automatically cut off to protect the subsequent devices from damage. The circuit and method proposed in this application example are implemented through full hardware, without the need for software participation, and have strong versatility; and there is no need to increase the withstand voltage of the subsequent devices to withstand the high voltage caused by the wrong connection, and the cost is low.

[0136] Reference Figure 6 , Figure 6 The circuit structure diagram of the protection circuit is used for the misconnection protection of the neutral and live wires of a three-phase air conditioner. The protection circuit includes: a rectifier diode D10, a power supply circuit (i.e. the aforementioned voltage stabilizing circuit), a voltage sampling unit (i.e. the aforementioned line voltage sampling circuit), a reference voltage unit (i.e. the aforementioned reference voltage conversion circuit), a comparison unit (i.e. the aforementioned voltage comparison circuit) and a switch control circuit (i.e. the aforementioned control circuit), a first terminal P1 and a second terminal P2 as input ends, the first terminal P1 is connected to the live wire C1, the second terminal P2 is connected to the neutral wire N, a third terminal P3 and a fourth terminal P4 as output ends, the third terminal P3 is electrically connected to the first terminal P1, and the fourth terminal P4 is electrically connected to the second terminal P2.

[0137] Next, the structure of each circuit is described in detail.

[0138] The power supply circuit includes: a resistor R1, a resistor R2, a voltage zener diode DZ1 and a capacitor E1. The input end of the resistor R1 is connected to the output end of the rectifier diode D, the two ends of the resistor R2 are respectively connected to the two ends of the voltage zener diode DZ1, and the input end of the resistor R2 is connected to the output end of the resistor R1. The two ends of the voltage zener diode DZ1 are also connected to the two ends of the capacitor E1, and the two ends of the capacitor E1 are connected to the fifth terminals P51 and P52.

[0139] The input voltage, i.e., the line voltage on the live wire C, is half-wave rectified by the rectifier diode D10, divided by the resistors R1 and R2, stabilized by the voltage regulator DZ1, and filtered by the capacitor E1 to obtain the stabilized voltage, i.e., the power supply voltage VDD required by the subsequent circuit.

[0140] The reference voltage unit includes a resistor R5 and a resistor R6.

[0141] The voltage VDD is divided by resistors R4 and R6 to obtain a threshold voltage V1 (i.e., the aforementioned reference voltage) of the protection circuit. The threshold voltage is usually set to a voltage sampling value obtained by a voltage sampling unit when the input voltage is about 300Vac. The output end of the reference voltage unit is connected to the comparison unit.

[0142] The voltage sampling unit includes: resistor R3, resistor R4, and electrolytic capacitor E2. The input end of resistor R3 is connected to the output end of rectifier diode D. The output end of resistor R3 is connected to one end of resistor R4. The other end of resistor R4 is connected to the second terminal P2. Both ends of resistor R4 are connected to both ends of electrolytic capacitor E2. The voltage sampling unit is connected to the input end of the comparison unit.

[0143] The line voltage of the live wire C and the voltage of the neutral wire N after being rectified by rectifier diode D10, after being half-wave rectified by rectifier diode D10, are divided by resistors R3 and R4, and the corresponding voltage sampling value V2 (i.e., the aforementioned line voltage sampling value) is obtained through the filtering of electrolytic capacitor E2, that is, the voltage difference sampling value of the line voltage of the live wire C and the line voltage of the neutral wire N.

[0144] Comparator IC2 of the comparison unit compares the threshold voltage V1 and the sampling voltage V2. When the input voltage is the normal live wire and neutral wire voltage, V1 > V2, and a high level is output; when the input voltage is the voltage of two live wires, V1 < V2, and a low level is output.

[0145] The switch control circuit includes: resistor R7, resistor R8, triode Q1, and relay RY1.

[0146] The resistor R7, resistor R8, triode Q1, and relay RY1 form a switch control circuit. When the comparator outputs a high level, triode Q1 conducts, controlling the switch S1 of relay RY1 to close, and the first terminal P1 is conducted with the third terminal P3. At this time, power can be supplied to the subsequent stage; when the comparator outputs a low level, triode Q1 does not conduct, and the switch S1 of relay RY1 disconnects the electrical connection between the first terminal P1 and the third terminal P3. At this time, the subsequent stage circuit is not powered, protecting the subsequent stage devices from damage.

[0147] The working process of the protection circuit is as follows:

[0148] 1. Obtain a stable power supply voltage, that is, the power supply voltage VDD, through the power supply circuit;

[0149] 2. Set a threshold voltage V1 through the reference voltage unit;

[0150] 3. Obtain a sampling voltage V2 corresponding to the input voltage through the voltage sampling unit;

[0151] 4. Compare the reference voltage V1 and the threshold voltage V2 through the comparison unit. When the input power supply is normal, V1 > V2. When the live wire and neutral wire of the input power supply are connected wrongly, resulting in loop 2 becoming two live wires, the obtained sampling voltage V2 increases, and V1 < V2;

[0152] 5. The switch control circuit controls the switching device based on the result output by the comparison unit. When V1 > V2, the switch is closed to control the electrical connection between the first terminal P1 and the third terminal P3 to be conducted; when V1 < V2, the switch is opened to control the electrical connection between the first terminal P1 and the third terminal P3 to be disconnected.

[0153] In this way, for the protection circuit of this application example, when the live wire and neutral wire of the air conditioner are correctly wired, the control switch S1 can be normally closed to supply power to the subsequent circuit; when the live wire and neutral wire of the air conditioner are wrongly connected, resulting in an increase in the input voltage of loop 2, the protection circuit automatically judges and opens the switch S1 to protect the devices in the subsequent circuit from being damaged. Without the need for software control, a low-cost all-hardware circuit is provided, solving the problem of device damage caused by the wrong connection of the live wire and neutral wire of a three-phase air conditioner, and solving the problem of a significant increase in the cost of the corresponding devices caused by the method of improving the voltage withstand of devices currently used for protecting against wrong connections of the live wire and neutral wire.

[0154] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A protection circuit, characterized in that: The protection circuit comprises: A first terminal and a second terminal as input terminals, the first terminal being connected to a first power line, and the second terminal being connected to a second power line; A third terminal and a fourth terminal as output terminals, the third terminal being electrically connected to the first terminal, and the fourth terminal being electrically connected to the second terminal; a voltage detection module, wherein an input end of the voltage detection module is connected to the first terminal and the second terminal, and is used to obtain a line voltage sampling value between the first power line and the second power line, generate a reference voltage for comparison with the line voltage sampling value, and generate a comparison result between the line voltage sampling value and the reference voltage; A control circuit, wherein an input end of the control circuit is connected to an output end of the voltage detection module, and is used to control an on-off state between the third terminal and the first terminal based on the comparison result.

2. The circuit according to claim 1, characterized in that The voltage detection module comprises: a reference voltage conversion module, wherein an input end of the reference voltage conversion module is connected to the first terminal and the second terminal, and is used to convert a line voltage between the first power line and the second power line into a reference voltage; A line voltage sampling circuit, wherein the input end of the line voltage sampling circuit is respectively connected to the input end of the reference voltage conversion module and the second terminal, and is used to obtain the line voltage sampling value; A voltage comparison circuit, wherein the input end of the voltage comparison circuit is connected to the output end of the reference voltage conversion module and the output end of the line voltage sampling circuit, and the output end of the voltage comparison circuit is connected to the input end of the control circuit, for generating a comparison result between the line voltage sampling value and the reference voltage.

3. The circuit according to claim 2, characterized in that The reference voltage conversion module comprises: a rectifier diode, wherein an input end of the rectifier diode is connected to the first terminal, and an output end of the rectifier diode is connected to an input end of the line voltage sampling circuit, and is used to rectify the line voltage between the first power line and the second power line; a voltage stabilizing circuit, the input end of which is connected to the output end of the rectifier diode, and is used to stabilize the line voltage between the first power line and the second power line after rectification to generate a regulated voltage; a fifth terminal connected to an output end of the voltage stabilizing circuit; A reference voltage conversion circuit, wherein the input end of the reference voltage conversion circuit is connected to the fifth terminal and is used to convert the regulated voltage to the reference voltage, and the output end of the reference voltage conversion circuit is connected to the input end of the voltage comparison circuit.

4. The circuit according to claim 2, characterized in that The voltage comparison circuit comprises: A comparator, wherein the input end of the comparator is respectively connected to the output end of the reference voltage conversion module and the line voltage sampling circuit, and the output end of the comparator is connected to the input end of the control circuit, for determining whether the reference voltage is less than or equal to the line voltage sampling value, and sending the detection result to the control circuit.

5. The circuit according to claim 3, characterized in that The voltage stabilizing circuit comprises: a first resistor, wherein an input end of the first resistor is connected to an output end of the rectifier diode; A voltage zener diode, an input end of the voltage zener diode is connected to an output end of the first resistor; A first capacitor, wherein an input end of the first capacitor is connected to the output end of the voltage stabilizing diode, and an output end of the first capacitor is connected to the fifth terminal.

6. The circuit according to claim 3, characterized in that The reference voltage conversion circuit comprises: A second resistor, wherein an input end of the second resistor is connected to the fifth terminal, and an output end of the second resistor is connected to an input end of the voltage comparison circuit.

7. The circuit according to claim 2, characterized in that The line voltage sampling circuit comprises: a third resistor, the third resistor being connected to the output end of the rectifier diode and the second terminal respectively; A second capacitor, wherein an input terminal of the second capacitor is connected to an output terminal of the third resistor, and an output terminal of the second capacitor is connected to an input terminal of the voltage comparison circuit.

8. The protection circuit according to claim 1, characterized in that: The control circuit comprises: a fourth resistor, wherein an input end of the fourth resistor is connected to an output end of the voltage detection module; A transistor, an input end of the transistor is connected to an output end of the fourth resistor; A relay, wherein the input end of the relay is connected to the output end of the transistor, and the output end of the relay is connected to the third terminal.

9. An air conditioner, characterized in that: The air conditioner comprises: a protection circuit and a multi-phase power supply network as claimed in any one of claims 1 to 8, wherein the protection circuit is connected to the multi-phase power supply network, and the multi-phase power supply network is a three-phase four-wire power supply network.

10. The air conditioner according to claim 9, characterized in that: The air conditioner also includes: a single-phase load circuit, wherein an input end of the single-phase load circuit is connected to the third terminal and the fourth terminal respectively; A fan load module, the input end of the fan load module is connected to the output end of the single-phase load circuit; A switching power supply load module, wherein the input end of the switching power supply load module is connected to the output end of the single-phase load circuit.

11. The air conditioner according to claim 10, characterized in that: The air conditioner also includes: An AC load module, wherein an input end of the AC load module is connected to the third terminal and the fourth terminal respectively.

12. The air conditioner according to claim 9, characterized in that: The air conditioner also includes: A multi-phase load circuit, the input end of which is connected to the three-phase four-wire power supply network; A compressor load module, wherein an input end of the compressor load module is connected to an output end of the multi-phase load circuit.

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