Over-temperature protection circuit and air conditioner

Abstract

The utility model discloses an over-temperature protection circuit and an air conditioner, and the over-temperature protection circuit comprises a thermistor which is used for detecting the working temperature of an intelligent power module and outputting a corresponding resistance voltage according to the working temperature; the linear temperature measurement circuit is used for being connected with the thermistor, and the linear temperature measurement circuit is used for conducting voltage conversion processing on the connected resistor voltage and outputting temperature detection voltage linearly related to the working temperature; the first input end of the comparison control circuit is used for being connected with the output end of the linear temperature measurement circuit, the second input end of the comparison control circuit is used for accessing a reference voltage, the first connecting end of the comparison control circuit is used for accessing a first power supply, and the second connecting end of the comparison control circuit is used for accessing a power supply end of the intelligent power module; the comparison control circuit is also used for disconnecting the intelligent power module and the first power supply when the temperature detection voltage is greater than the reference voltage; the technical scheme of the utility model aims to reduce the occurrence of over-temperature protection abnormity of the intelligent power module under the condition of rapid temperature rise.

Description

Technical Field

[0001] This utility model relates to the field of air conditioner technology, and in particular to an over-temperature protection circuit and an air conditioner. Background Technology

[0002] Currently, most inverter air conditioners control the compressor's output power by incorporating an Intelligent Power Module (IPM). To prevent damage to the power components inside the IPM from overheating during operation, a thermistor is installed externally for temperature detection. However, because the thermistor is located close to the internal circuitry of the IPM, it is susceptible to interference from the internal circuitry, causing non-linear voltage drift in the thermistor's output. This results in the over-temperature protection within the IPM failing to function effectively when the temperature rises rapidly. Utility Model Content

[0003] The main purpose of this utility model is to provide an over-temperature protection circuit and an air conditioner, which aims to reduce the occurrence of over-temperature protection abnormalities in intelligent power modules under rapid heating.

[0004] To achieve the above objectives, the present invention proposes an over-temperature protection circuit, which is applied to an intelligent power module. The over-temperature protection circuit includes:

[0005] A thermistor is used to detect the operating temperature of the intelligent power module and output a corresponding resistance voltage.

[0006] A linear temperature measurement circuit is electrically connected to the thermistor. The linear temperature measurement circuit is used to perform voltage conversion processing on the input resistor voltage and output a temperature detection voltage that is linearly related to the working temperature.

[0007] The comparison control circuit has its first input terminal connected to the output terminal of the linear temperature measurement circuit, its second input terminal for connecting to a reference voltage, its first connection terminal for connecting to a first power supply, and its second connection terminal for connecting to the power supply terminal of the intelligent power module.

[0008] The comparison control circuit is also used to disconnect the intelligent power module from the first power supply when the temperature detection voltage is greater than the reference voltage.

[0009] In some embodiments, the linear temperature sensing circuit includes:

[0010] A first conversion circuit is electrically connected to the thermistor. The first conversion circuit is used to invert and amplify the voltage of the resistor before outputting it.

[0011] The second conversion circuit has its input terminal connected to the input terminal of the first conversion circuit. It further inverts and amplifies the inverted resistor voltage, performs signal superposition processing, and outputs the corresponding temperature detection voltage.

[0012] In some embodiments, the first conversion circuit includes:

[0013] The first amplifier includes a first non-inverting input pin, a first inverting input pin, and a first output pin, wherein the first inverting input pin and the first output pin are respectively connected to the two ends of the thermistor;

[0014] The first resistor has its first end connected to the second power supply and its second end connected to the first inverting input pin.

[0015] The second resistor is connected in series between the first positive input pin and ground.

[0016] In some embodiments, the second conversion circuit includes:

[0017] The second amplifier includes a second non-inverting input pin, a second inverting input pin, and a second output pin, wherein the second output pin is the output terminal of the second conversion circuit.

[0018] The third resistor has its first end connected to the input terminal of the second conversion circuit, and its second end connected to the second inverting input pin.

[0019] The fourth resistor is connected in series between the second positive input pin and ground;

[0020] The fifth resistor and the sixth resistor are connected as follows: the first end of the fifth resistor is connected to the second output pin, the second end of the fifth resistor is connected to the second inverting input pin and is connected to the first end of the sixth resistor, and the second end of the sixth resistor is used to connect to the second power supply.

[0021] In some embodiments, the comparison control circuit includes:

[0022] A switching circuit, the input terminal of which is the first connection terminal of the comparison control circuit, and the output terminal of which is the second connection terminal of the comparison control circuit;

[0023] The comparator circuit has its inverting input terminal as the first input terminal of the switching circuit, its non-inverting input terminal as the second input terminal of the switching circuit, and its output terminal connected to the controlled terminal of the switching circuit.

[0024] The comparison circuit is used to control the switching circuit to turn off when the temperature detection voltage is greater than the reference voltage.

[0025] In some embodiments, the comparison circuit includes:

[0026] The comparator includes a third non-inverting input pin, a third inverting input pin, and a third output pin. The third non-inverting input pin is the inverting input terminal of the comparator circuit, and the third output pin is the output terminal of the comparator circuit.

[0027] The seventh resistor has its first end connected to the non-inverting input of the comparator circuit, and its second end connected to the third non-inverting input pin.

[0028] In some embodiments, the switching circuit includes:

[0029] The switching transistor has its input terminal as the input terminal of the switching circuit, its output terminal as the output terminal of the switching circuit, and its controlled terminal as the controlled terminal of the switching circuit.

[0030] The eighth resistor is connected in parallel to the controlled terminal and the output terminal of the switching transistor.

[0031] In some embodiments, the comparison control circuit further includes:

[0032] A voltage regulator circuit is connected in series between the output terminal of the comparator circuit and the controlled terminal of the switch circuit. The voltage regulator circuit is used to regulate the control signal output by the comparator circuit and then output it to the switch circuit.

[0033] In some embodiments, the voltage regulator circuit includes:

[0034] The ninth, tenth, and eleventh resistors are provided, with the first end of the ninth and tenth resistors respectively connected to the output terminal of the comparator circuit, and the second ends of the ninth, tenth, and eleventh resistors respectively connected to the controlled terminal of the switch circuit.

[0035] A Zener diode is connected in series between the output terminal of the comparator circuit and the first terminal of the eleven resistors.

[0036] This utility model also proposes an air conditioner, including an intelligent power module, a thermistor and the above-mentioned over-temperature protection circuit;

[0037] The thermistor is attached to the power device of the intelligent power module, and the over-temperature protection circuit is electrically connected to the intelligent power module.

[0038] This utility model's technical solution, by setting up a linear temperature measurement circuit, performs voltage conversion processing on the resistance voltage output by the thermistor, eliminating the nonlinear drift of the resistance voltage. This allows the comparison control circuit to accurately control the connection between the power supply terminal of the intelligent power module and the first power supply based on the processed temperature detection voltage. This reduces the nonlinear drift of the output voltage caused by the thermistor due to the influence of the internal circuit of the intelligent power module, thus preventing the intelligent power module from malfunctioning due to over-temperature protection during rapid heating. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of an embodiment of the over-temperature protection circuit of this utility model;

[0041] Figure 2 This is a schematic diagram of another embodiment of the over-temperature protection circuit of this utility model;

[0042] Figure 3 This is a schematic diagram of another embodiment of the over-temperature protection circuit of this utility model;

[0043] Figure 4 This is a schematic diagram of another embodiment of the over-temperature protection circuit of this utility model;

[0044] Figure 5 This is a circuit structure diagram of an embodiment of the over-temperature protection circuit of this utility model.

[0045] Explanation of icon numbers:

[0046] label name label name 100 Thermistor 330 Voltage regulator circuit 200 Linear temperature measurement circuit U1~U2 First amplifier ~ Second amplifier 210 First conversion circuit U3 comparator 220 Second conversion circuit Q1 Switching transistor 300 Comparison control circuit DZ1 Zener diode 310 Switching circuit R1~R11 First resistor ~ Eleventh resistor 320 Comparator circuit

[0047] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0048] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0049] Furthermore, in this utility model, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0050] This invention proposes an over-temperature protection circuit for use in intelligent power modules.

[0051] With the development of the national economy and the continuous improvement of people's living standards, air conditioning has become a necessity in daily life. Due to the introduction of national energy efficiency standards for some household appliances, inverter air conditioners have significant development potential in my country due to their superior performance. Inverter air conditioners utilize inverter technology to control the speed of the compressor motor, thereby effectively controlling its output power to achieve energy saving, noise reduction, improved cooling / heating effects, and enhanced comfort. Intelligent power modules highly integrate power devices, drive circuits, and protection circuits onto a small package substrate, featuring high integration, comprehensive functions, and stable performance. This greatly simplifies the complexity of the compressor drive circuit while effectively improving circuit reliability. Currently, intelligent power modules are widely used in household inverter appliances. Therefore, protecting intelligent power modules is particularly important.

[0052] The intelligent power module is a novel module using IGBTs as power devices. This power module integrates the output power element IGBT, drive circuit, and various protection circuits into the same module. Compared with ordinary IGBTs, it further improves system performance and reliability. Moreover, because the intelligent power module has relatively low conduction and switching losses, the size of the heat sink can be reduced, thus reducing the overall system size.

[0053] The intelligent power module internally incorporates gate drive control, fault detection, and multiple protection circuits. An integrated current sensor monitors the IGBT's main circuitry, while internal fault protection circuits detect overcurrent, short circuits, overtemperature, and undervoltage control. This prevents damage to the power chip caused by system interference or overload.

[0054] For over-temperature protection, it is ineffective in situations of rapid temperature rise, such as motor stall or overcurrent. If a malfunction in the cooling system (e.g., loose heatsink, poor contact, or fan stoppage) triggers the over-temperature protection, the smart power module should no longer be used because the junction temperature Tj of the power silicon wafer may have exceeded the maximum rating (150°C).

[0055] Therefore, a circuit needs to be designed to effectively monitor the rapid temperature rise of the power silicon wafer.

[0056] Reference Figure 1 In one embodiment, the over-temperature protection circuit includes:

[0057] Thermistor 100 is used to detect the operating temperature of the intelligent power module and output a corresponding resistance voltage.

[0058] A linear temperature measurement circuit 200 is electrically connected to the thermistor 100. The linear temperature measurement circuit 200 is used to perform voltage conversion processing on the input resistor voltage and output a temperature detection voltage that is linearly related to the working temperature.

[0059] The comparison control circuit 300 has a first input terminal connected to the output terminal of the linear temperature measurement circuit 200, a second input terminal for connecting to a reference voltage, a first connection terminal for connecting to a first power supply, and a second connection terminal for connecting to the power supply terminal of the intelligent power module.

[0060] The comparison control circuit 300 is also used to disconnect the intelligent power module from the first power supply when the temperature detection voltage is greater than the reference voltage.

[0061] In this embodiment, the thermistor 100 is an external resistor of the intelligent power module (specifically, it can be a platinum resistance thermometer), which is attached to the power device of the intelligent power module to collect the operating temperature of the power device and output the corresponding resistance voltage.

[0062] The intelligent power module can be applied to electrical appliances such as air conditioners, refrigerators, and washing machines, and is powered through the DC bus converted by these electrical appliances.

[0063] Specifically, after the electrical equipment is powered on, its internal power module converts the incoming AC power and outputs the first power supply to the intelligent power module and the over-temperature protection circuit through the DC bus. At this time, current flows through the circuit where the thermistor 100 is located, and it can output the corresponding resistance voltage to the linear temperature measuring circuit 200 according to the detected operating temperature of the power device.

[0064] It is understandable that, since the thermistor 100 is close to the internal circuit of the intelligent power module, it is easily affected by the internal circuit, causing the voltage output of the thermistor 100 to drift nonlinearly. Therefore, the linear temperature measurement circuit 200 needs to perform voltage conversion processing on the resistor voltage. Specifically, the drift caused by the resistor voltage can be eliminated by introducing a bias voltage or by signal superposition, and the output temperature detection voltage is linearly related to the operating temperature.

[0065] Therefore, after the temperature detection voltage is connected to the comparison control circuit 300, since the temperature detection voltage has no drift, the comparison control circuit 300 can compare the voltage value of the temperature detection voltage with the voltage value of the reference voltage by connecting the reference voltage representing the critical temperature value. When the power module is not overheated, due to the inherent characteristics of the thermistor 100, its output resistance voltage is also low. After voltage conversion processing by the linear temperature measurement circuit 200, the output temperature detection voltage is lower than the reference voltage. Based on the comparison result, the comparison control circuit 300 maintains the connection between the power supply terminal of the intelligent power module and the first power supply, so that the intelligent power module is powered on and working. When the power module is overheated, the resistance voltage output by the thermistor 100, after passing through the linear temperature measurement circuit 200, converts the output temperature detection voltage to a value higher than the reference voltage. Based on the comparison result, the comparison control circuit 300 disconnects the connection between the power supply terminal of the intelligent power module and the first power supply, so that the intelligent power module stops working.

[0066] This utility model's technical solution, by setting up a linear temperature measurement circuit 200, performs voltage conversion processing on the resistance voltage output by the thermistor 100, eliminating the nonlinear drift of the resistance voltage. This allows the comparison control circuit 300 to accurately control the connection between the power supply terminal of the intelligent power module and the first power supply based on the processed temperature detection voltage. This reduces the nonlinear drift of the output voltage of the thermistor 100 caused by the influence of the internal circuit of the intelligent power module, thus preventing the intelligent power module from malfunctioning due to over-temperature protection during rapid heating.

[0067] Reference Figure 1 and Figure 2 In one embodiment, the linear temperature sensing circuit 200 includes:

[0068] The first conversion circuit 210 is electrically connected to the thermistor 100. The first conversion circuit 210 is used to output the voltage of the resistor after inverting and amplifying it.

[0069] The second conversion circuit 220 has its input terminal connected to the input terminal of the first conversion circuit 210. It further inverts and amplifies the inverted resistor voltage, performs signal superposition processing, and outputs the corresponding temperature detection voltage.

[0070] In this embodiment, the linear temperature sensing circuit 200 processes the resistor voltage using signal superposition. Specifically, after the resistor voltage of the thermistor 100 is input to the first conversion circuit 210, it undergoes inverting amplification by the first conversion circuit 210 to match the signal superimposed in the second conversion circuit 220. Therefore, when the second conversion circuit 220 receives the processed resistor voltage, it superimposes the resistor voltage with the signal generated internally and then performs inverting amplification again, outputting a positive-phase, drift-free temperature detection voltage. That is, the temperature detection voltage is linearly correlated with the operating temperature, thus enabling the temperature detection voltage to accurately reflect the operating temperature.

[0071] Reference Figure 1 , Figure 2 and Figure 5 In one embodiment, the first conversion circuit 210 includes:

[0072] The first amplifier U1 includes a first non-inverting input pin, a first inverting input pin, and a first output pin. The first inverting input pin and the first output pin are respectively connected to the two ends of the thermistor 100.

[0073] The first resistor R1 has its first end connected to the second power supply and its second end connected to the first inverting input pin.

[0074] The second resistor R2 is connected in series between the first positive input pin and ground.

[0075] The second conversion circuit 220 includes:

[0076] The second amplifier U2 includes a second non-inverting input pin, a second inverting input pin, and a second output pin, wherein the second output pin is the output terminal of the second conversion circuit 220.

[0077] The third resistor R3 has its first end connected to the input terminal of the second conversion circuit 220, and its second end connected to the second inverting input pin.

[0078] The fourth resistor R4 is connected in series between the second positive input pin and ground;

[0079] The fifth resistor R5 and the sixth resistor R6 are connected. The first end of the fifth resistor R5 is connected to the second output pin, the second end of the fifth resistor R5 is connected to the second inverting input pin, and is connected to the first end of the sixth resistor R6. The second end of the sixth resistor R6 is used to connect to the second power supply.

[0080] In this embodiment, the first resistor R1, the second resistor R2 and the first amplifier U1 form a single-loop inverting amplifier circuit, and the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6 and the second amplifier U2 form a compound-loop inverting amplifier circuit.

[0081] Specifically, the output voltage of the first conversion circuit 210 is:

[0082]

[0083] Among them, v 01 V is the output voltage of the first conversion circuit 210. R R is the voltage of the second power supply, RT is the resistance of the thermistor 100, and R1 is the resistance of the first resistor R1.

[0084] For the second conversion circuit 220, there are two input signals, namely V R and V 01 The output voltage of the second conversion circuit 220 is:

[0085]

[0086] Taking a platinum resistance thermometer 100 as an example, the resistance of the platinum resistance thermometer is 100Ω at 0℃, and the temperature coefficient is 0.4%Ω / ℃. Let T represent the temperature, then:

[0087] R T =100 + 0.4T;

[0088] Substituting into the above equation, we get:

[0089]

[0090] At a temperature of 0℃, adjust resistor R6 to make V 02 If the result is zero, then:

[0091]

[0092] At a temperature of 150℃, adjust the resistance of the fifth resistor R5 to make the output voltage V 02 Given 150mV, we get:

[0093]

[0094] After the above adjustments, the output voltage of the second conversion circuit 220 (i.e., the temperature detection voltage in this application) is:

[0095]

[0096] Clearly, the output voltage is linearly related to temperature, eliminating the nonlinear error of traditional sampling circuits.

[0097] Reference Figure 1 and Figure 3 In one embodiment, the comparison control circuit 300 includes:

[0098] The switching circuit 310 has its input terminal as the first connection terminal of the comparison control circuit 300 and its output terminal as the second connection terminal of the comparison control circuit 300.

[0099] The comparator circuit 320 has its inverting input terminal as the first input terminal of the switch circuit 310, its non-inverting input terminal as the second input terminal of the switch circuit 310, and its output terminal connected to the controlled terminal of the switch circuit 310.

[0100] The comparison circuit 320 is used to control the switching circuit 310 to turn off when the temperature detection voltage is greater than the reference voltage.

[0101] In this embodiment, the switching circuit 310 can be a relay, a MOSFET, an IGBT, etc., and the comparison circuit 320 can include a comparator U3 and its peripheral circuits.

[0102] Reference Figure 1 , Figure 3 and Figure 5 In one embodiment, the comparison circuit 320 includes:

[0103] Comparator U3 includes a third non-inverting input pin, a third inverting input pin, and a third output pin. The third non-inverting input pin is the inverting input terminal of the comparator circuit 320, and the third output pin is the output terminal of the comparator circuit 320.

[0104] The seventh resistor R7 has its first end connected to the non-inverting input of the comparator circuit 320, and its second end connected to the third non-inverting input pin.

[0105] In this embodiment, the seventh resistor R7 is used to divide the connected second power supply to provide a corresponding reference voltage for the comparator U3.

[0106] Reference Figure 1 , Figure 3 and Figure 5 In one embodiment, the switching circuit 310 includes:

[0107] The switching transistor Q1 has its input terminal as the input terminal of the switching circuit 310, its output terminal as the output terminal of the switching circuit 310, and its controlled terminal as the controlled terminal of the switching circuit 310.

[0108] The eighth resistor R8 is connected in parallel to the controlled terminal of the switch Q1 and the output terminal of the switch Q1.

[0109] In this embodiment, the type of the switching transistor Q1 is adapted to the level of the control signal output by the comparator U3. When the temperature detection voltage is greater than the reference voltage, the level of the control signal is high, and the switching transistor Q1 is a PNP transistor or a PMOS transistor. When the temperature detection voltage is greater than the reference voltage, the level of the control signal is low, and the switching transistor Q1 is an NPN transistor or an NMOS transistor.

[0110] The switching transistor Q1 is specifically used to connect or disconnect the first power supply to the power supply terminal of the intelligent power module according to the input control signal. The eighth resistor R8 is a bleeder resistor, used to release the junction capacitance charge of the switching transistor Q1 when it is controlled to turn off.

[0111] Reference Figure 1 , Figure 4 and Figure 5 In one embodiment, the comparison control circuit 300 further includes:

[0112] A voltage regulator circuit 330 is connected in series between the output terminal of the comparator circuit 320 and the controlled terminal of the switch circuit 310. The voltage regulator circuit 330 is used to regulate the control signal output by the comparator circuit 320 and then output it to the switch circuit 310.

[0113] In this embodiment, the voltage regulator circuit 330 is used to regulate the control signal output by the comparator circuit 320 to avoid excessive instantaneous current of the control signal or voltage jitter caused by the control signal, which could damage the controlled terminal of the switching transistor Q1.

[0114] Specifically, the voltage regulator circuit 330 includes:

[0115] The ninth resistor R9, the tenth resistor R10, and the eleventh resistor R11 are connected to the output terminal of the comparator circuit 320, respectively, and the second terminals of the ninth resistor R9, the tenth resistor R10, and the eleventh resistor R11 are connected to the controlled terminal of the switch circuit 310, respectively.

[0116] Zener diode DZ1 is connected in series between the output terminal of the comparator circuit 320 and the first terminal of the eleven resistors.

[0117] Among them, the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11 serve to limit current and divide voltage. The Zener diode DZ1 is used to break down when the voltage of the control signal reaches the voltage regulation threshold, so as to stabilize the maximum value of the voltage of the control signal at the voltage regulation threshold.

[0118] This utility model also proposes an air conditioner, which includes an intelligent power module, a thermistor 100, and the over-temperature protection circuit described above. The thermistor 100 is attached to the power device of the intelligent power module, and the over-temperature protection circuit is electrically connected to the intelligent power module. The specific structure of the air conditioner is as described in the above embodiments. Since this air conditioner adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0119] The above description is only an optional embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. An over-temperature protection circuit, applied to a smart power module, characterized in that, The over-temperature protection circuit includes: A thermistor is used to detect the operating temperature of the intelligent power module and output a corresponding resistance voltage. A linear temperature measurement circuit is electrically connected to the thermistor. The linear temperature measurement circuit is used to perform voltage conversion processing on the input resistor voltage and output a temperature detection voltage that is linearly related to the working temperature. The comparison control circuit has a first input terminal connected to the output terminal of the linear temperature measurement circuit, a second input terminal for connecting to a reference voltage, a first connection terminal for connecting to a first power supply, and a second connection terminal for connecting to the power supply terminal of the intelligent power module. The comparison control circuit is also used to disconnect the intelligent power module from the first power supply when the temperature detection voltage is greater than the reference voltage.

2. The over-temperature protection circuit as described in claim 1, characterized in that, The linear temperature measurement circuit includes: A first conversion circuit is electrically connected to the thermistor. The first conversion circuit is used to invert and amplify the voltage of the resistor before outputting it. The second conversion circuit has its input terminal connected to the input terminal of the first conversion circuit. It further inverts and amplifies the inverted resistor voltage, performs signal superposition processing, and outputs the temperature detection voltage.

3. The over-temperature protection circuit as described in claim 2, characterized in that, The first conversion circuit includes: The first amplifier includes a first non-inverting input pin, a first inverting input pin, and a first output pin, wherein the first inverting input pin and the first output pin are respectively connected to the two ends of the thermistor; The first resistor has its first end connected to the second power supply and its second end connected to the first inverting input pin. The second resistor is connected in series between the first positive input pin and ground.

4. The over-temperature protection circuit as described in claim 2, characterized in that, The second conversion circuit includes: The second amplifier includes a second non-inverting input pin, a second inverting input pin, and a second output pin, wherein the second output pin is the output terminal of the second conversion circuit. The third resistor has its first end connected to the input terminal of the second conversion circuit, and its second end connected to the second inverting input pin. The fourth resistor is connected in series between the second positive input pin and ground; The fifth resistor and the sixth resistor are connected as follows: the first end of the fifth resistor is connected to the second output pin, the second end of the fifth resistor is connected to the second inverting input pin and is connected to the first end of the sixth resistor, and the second end of the sixth resistor is used to connect to the second power supply.

5. The over-temperature protection circuit as described in claim 1, characterized in that, The comparison control circuit includes: A switching circuit, the input terminal of which is the first connection terminal of the comparison control circuit, and the output terminal of which is the second connection terminal of the comparison control circuit; The comparator circuit has its inverting input terminal as the first input terminal of the switching circuit, its non-inverting input terminal as the second input terminal of the switching circuit, and its output terminal connected to the controlled terminal of the switching circuit. The comparison circuit is used to control the switching circuit to turn off when the temperature detection voltage is greater than the reference voltage.

6. The over-temperature protection circuit as described in claim 5, characterized in that, The comparison circuit includes: The comparator includes a third non-inverting input pin, a third inverting input pin, and a third output pin. The third non-inverting input pin is the inverting input terminal of the comparator circuit, and the third output pin is the output terminal of the comparator circuit. The seventh resistor has its first end connected to the non-inverting input of the comparator circuit, and its second end connected to the third non-inverting input pin.

7. The over-temperature protection circuit as described in claim 5, characterized in that, The switching circuit includes: The switching transistor has its input terminal as the input terminal of the switching circuit, its output terminal as the output terminal of the switching circuit, and its controlled terminal as the controlled terminal of the switching circuit. The eighth resistor is connected in parallel to the controlled terminal and the output terminal of the switching transistor.

8. The over-temperature protection circuit as described in claim 5, characterized in that, The comparison control circuit further includes: A voltage regulator circuit is connected in series between the output terminal of the comparator circuit and the controlled terminal of the switch circuit. The voltage regulator circuit is used to regulate the control signal output by the comparator circuit and then output it to the switch circuit.

9. The over-temperature protection circuit as described in claim 8, characterized in that, The voltage regulator circuit includes: The ninth, tenth, and eleventh resistors are provided, with the first end of the ninth and tenth resistors respectively connected to the output terminal of the comparator circuit, and the second ends of the ninth, tenth, and eleventh resistors respectively connected to the controlled terminal of the switch circuit. A Zener diode is connected in series between the output terminal of the comparator circuit and the first terminal of the eleven resistors.

10. An air conditioner, characterized in that, Includes a smart power module, a thermistor, and an over-temperature protection circuit as described in any one of claims 1-9; The thermistor is attached to the power device of the intelligent power module, and the over-temperature protection circuit is electrically connected to the intelligent power module.

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