An online monitoring circuit and monitoring method for semiconductor refrigeration chip

Abstract

The present invention relates to the field of semiconductor refrigeration, and discloses an online monitoring circuit and monitoring method for a semiconductor refrigeration plate, comprising a semiconductor refrigeration plate, a switch element, a voltage detection circuit and a controller; at least one end of the semiconductor refrigeration plate is connected to a DC power supply through a switch element to form a refrigeration and heating circuit; when the switch element is controlled to disconnect the refrigeration and heating circuit of the semiconductor refrigeration plate, the semiconductor refrigeration plate and the voltage detection circuit form a detection circuit; the voltage detection circuit is used to detect the voltage change at both ends of the semiconductor refrigeration plate and output a temperature difference voltage signal; the controller outputs a detection pulse signal to control the switch element to shut down the refrigeration and heating circuit of the semiconductor refrigeration plate, and reads the temperature difference voltage signal at the beginning of shutting down the refrigeration and heating circuit. The present invention detects the temperature difference voltage generated at both ends of the semiconductor refrigeration plate due to the Seebeck effect through the characteristics of the semiconductor refrigeration plate itself, thereby determining the working state of the semiconductor refrigeration plate.

Description

Technical Field

[0001] The invention relates to the technical field of refrigeration and dehumidification, and in particular to an online monitoring circuit and a monitoring method for a semiconductor refrigeration sheet. Background Art

[0002] Semiconductor cooling chip, also called thermoelectric cooling chip, is a heat pump. Its advantage is that it has no sliding parts and is used in some places where space is limited, reliability is high, and there is no refrigerant pollution. Using the Peltier effect of semiconductor materials, when direct current passes through a thermocouple made of two different semiconductor materials in series, heat can be absorbed and released at both ends of the thermocouple respectively, achieving the purpose of cooling. It is a refrigeration technology that produces negative thermal resistance, which is characterized by no moving parts and relatively high reliability.

[0003] For electrical equipment in switch cabinets, the optimal humidity should be maintained between 30% and 60%, because if the humidity exceeds 60%, condensation is likely to form, which will have an adverse effect on the insulation performance of electrical equipment. Because when water vapor enters the high-voltage switch cabinet, it will be electrolyzed into hydrogen ions and oxygen ions by the strong electromagnetic field in the switch cabinet, especially by the tip discharge process at the connection between the cable and the copper busbar, and the oxygen ions will react with the oxygen molecules in the air to produce ozone. The long-term erosion of the insulating material by ozone and weakly acidic corrosive gases will cause the insulation performance of electrical equipment in the high-voltage switch cabinet to deteriorate. In addition, water vapor will condense into crystal water on the surface of the insulating material, causing a short circuit in the line and also reducing the insulation performance of the switch cabinet.

[0004] The dehumidifiers for switch cabinets currently on the market use semiconductor refrigeration chips for cooling and dehumidification. They can create a cold end inside the product that can be up to 30°C lower than the ambient temperature, and use a fan to force the relatively humid air in the cabinet to pass through the cold end, thereby continuously generating condensation at the cold end. Continuous condensation eventually leads to condensed water, which is collected and discharged outside the cabinet, thereby greatly reducing the humidity and moisture content in the cabinet. Even when the external environment cools down significantly, condensation will no longer occur due to the very little moisture in the cabinet, truly keeping the inside of the switch cabinet dry.

[0005] Due to the importance of switch cabinet dehumidification, it is necessary to monitor the working status of semiconductor refrigeration chips. At present, whether the semiconductor refrigeration chips in use can work normally is generally measured by adding detection devices to measure the resistance or current on the working circuit of the semiconductor refrigeration chips or the cooling temperature of the semiconductor refrigeration chips, but none of them can meet the requirements of effectiveness, accuracy and low cost at the same time. Summary of the invention

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide an online monitoring circuit for a semiconductor refrigeration plate, which adopts a detection circuit that is as simple as possible to achieve the requirements of effectiveness, accuracy and low cost.

[0007] To achieve the above object, the present invention provides an online monitoring circuit for a semiconductor refrigeration chip, comprising a semiconductor refrigeration chip, a switch element, a first voltage detection circuit and a controller;

[0008] The semiconductor refrigeration chip is connected to a power source to form a refrigeration and heating circuit, and the semiconductor refrigeration chip is connected to a first voltage detection circuit to form a detection circuit;

[0009] The switch element is connected to the cooling and heating circuit to shut down or close the cooling and heating circuit;

[0010] The first voltage detection circuit is used to detect the voltage change on the semiconductor refrigeration chip and output a first detection signal;

[0011] The controller controls the switch element to turn off or turn on the cooling and heating circuit, selects at least one of the time spans for turning off each cooling and heating circuit as a detection period, and the controller reads the first detection signal within the detection period.

[0012] When power is loaded on the two ends of the semiconductor refrigeration plate, a temperature difference will be formed on the two sides of the semiconductor refrigeration plate. When the power is turned off, the temperature difference on the two sides of the semiconductor refrigeration plate will produce a detectable temperature difference voltage. By detecting the temperature difference voltage, a first detection signal is formed to confirm the working status of the semiconductor refrigeration plate.

[0013] Furthermore, the switch element is a double-group linkage switch, and the switch element includes a first common terminal, a first normally open terminal, a first normally closed terminal, a second common terminal, a second normally open terminal, and a second normally closed terminal. The positive and negative electrodes of the power supply are respectively connected to the first normally open terminal and the second normally open terminal; the two input terminals of the detection circuit are respectively connected to the first normally closed terminal and the second normally closed terminal; the two ends of the semiconductor refrigeration film are respectively connected to the first common terminal and the second common terminal; the switch element is used to switch the semiconductor refrigeration film to be connected only to the cooling and heating circuit or only to the detection circuit. The first voltage detection circuit is used to detect the voltage difference between the two ends of the semiconductor refrigeration film.

[0014] Furthermore, the switch element and the semiconductor refrigeration sheet are connected in series and connected to a power source to form a cooling and heating circuit; the first voltage detection circuit is connected in parallel to both ends of the switch element; the semiconductor refrigeration sheet and the first voltage detection circuit are connected in series and connected to a power source to form a detection circuit. The controller obtains the voltage at both ends of the semiconductor refrigeration sheet by the difference between the preset power supply voltage and the voltage at the second end of the semiconductor refrigeration sheet.

[0015] Furthermore, the first end of the semiconductor refrigeration film is connected to the positive electrode of the power supply, and the second end of the semiconductor refrigeration film is connected to the negative electrode of the power supply through a switching element; the first voltage detection circuit is connected in parallel at both ends of the switching element.

[0016] Furthermore, it also includes a second voltage detection circuit, which is used to detect the voltage of the power supply and output a second detection signal to the controller;

[0017] The controller obtains the voltages at both ends of the semiconductor refrigeration plate by comparing the difference between the power supply voltage corresponding to the second detection signal and the voltage at the second end of the semiconductor refrigeration plate corresponding to the first detection signal.

[0018] Furthermore, the first voltage detection circuit is a resistor voltage divider circuit. The first input end of the first voltage detection circuit is connected to the second end of the semiconductor refrigeration plate, and the second input end of the first voltage detection circuit is connected to the negative electrode of the power supply, and the voltage to be detected is reduced to within the operating voltage range allowed by the controller through the voltage divider detection circuit.

[0019] Furthermore, the second voltage detection circuit is a resistance voltage divider circuit, the first input terminal of the second voltage detection circuit is connected to the positive electrode of the power supply, and the second input terminal of the second voltage detection circuit is connected to the negative electrode of the power supply. By detecting the power supply voltage, the influence of power supply voltage fluctuation caused by load changes can be overcome, which affects the measurement of the temperature difference voltage of the semiconductor refrigeration plate; the second voltage detection circuit and the first voltage detection circuit have the same voltage division ratio, which facilitates the comparison and calculation of the second voltage detection circuit and the first voltage detection circuit.

[0020] Furthermore, the switch element is a MOS tube, which has a relatively small on-resistance and a large through current.

[0021] Furthermore, the controller reads the first detection signal within 1 second after the detection cycle begins. The thermal damping coefficient of the semiconductor refrigeration chip is small, and the temperature difference voltage of the semiconductor refrigeration chip will drop rapidly. It needs to be collected in a short time to ensure the measurement accuracy. At the same time, the detection time is short and does not affect the working state of the semiconductor refrigeration chip.

[0022] The present invention also provides a monitoring method for an online monitoring circuit of a semiconductor refrigeration plate, wherein the controller executes a control program, comprising the steps of:

[0023] Step S1, disconnecting the cooling and heating circuit of the semiconductor refrigeration plate;

[0024] Step S2, collecting a first detection signal output by a first voltage detection circuit;

[0025] Step S3, comparing the first detection signal with the internal threshold to determine the working state of the semiconductor refrigeration chip;

[0026] Step S4, when it is determined that the working state of the semiconductor refrigeration piece is normal, jump to step S5; when it is determined that the working state of the semiconductor refrigeration piece is abnormal, jump to the abnormality handling procedure S6;

[0027] Step S5, closing the cooling and heating circuit of the semiconductor refrigeration plate.

[0028] Furthermore, the controller further includes a second input terminal, and the second input terminal is used to input a second detection signal;

[0029] The step S2 is changed to step S2': collecting a first detection signal output by the first voltage detection circuit; collecting a second detection signal output by the second voltage detection circuit;

[0030] The step S3 is changed to step S3': judging the working state of the semiconductor refrigeration plate by the difference between the first detection signal and the second detection signal.

[0031] Compared with the existing detection of semiconductor refrigerators, the feature of the present invention is that it uses the characteristics of the semiconductor refrigerator itself, temporarily disconnects the cooling and heating circuit of the refrigerator, detects the temperature difference voltage generated at both ends of the semiconductor refrigerator due to the Seebeck effect, and thus determines the working state of the semiconductor refrigerator; this technical solution requires fewer devices, is low in cost, and can effectively and accurately measure the working state of the semiconductor refrigerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of an online voltage detection circuit of a semiconductor refrigeration plate of the present invention.

[0033] Figure 2 It is a schematic diagram of an online voltage detection circuit of another semiconductor refrigeration plate of the present invention.

[0034] Figure 3 It is a schematic diagram of an online voltage detection circuit of a semiconductor refrigeration plate according to a preferred embodiment of the present invention.

[0035] Figure 4 yes Figure 3 Test waveform of the circuit.

[0036] Figure 5 yes Figure 2 Control flow chart of the circuit.

[0037] Figure 6 yes Figure 3 Control flow chart of the circuit. DETAILED DESCRIPTION

[0038] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0039] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0040] like Figure 1 As shown, a schematic diagram of an online voltage detection circuit of a semiconductor refrigeration plate of the present invention. It includes a semiconductor refrigeration plate 1, a switch K1, a first voltage detection circuit 2 and a controller 3. The switch K1 is a double-group linkage switch, including K1A and K1B, the common end of the switch K1A is connected to one end of the semiconductor refrigeration plate, the normally open contact of the switch K1A is connected to the positive electrode VDD of the power supply, and the normally closed contact of the switch K1A is connected to the first input end of the first voltage detection circuit 2; the common end of the switch K1B is connected to the other end of the semiconductor refrigeration plate, the normally open contact of the switch K1B is connected to the negative electrode VSS of the power supply, and the normally closed contact of the switch K1B is connected to the second input end of the first voltage detection circuit 2.

[0041] Refrigeration state: When the common end and the normally open contact of switches K1A and K1B are connected, the semiconductor refrigeration chip 1 is connected to the power supply to form a cooling and heating circuit, and the semiconductor refrigeration chip 1 starts to work. Under the Peltier effect, the semiconductor refrigeration chip 1 generates a temperature difference on the two sides of the semiconductor refrigeration chip 1, generating heat while cooling. In this specific application, its cooling function is taken, so the cooling and heating circuit is hereinafter referred to as the cooling circuit, and its working state is hereinafter referred to as the cooling state. The thermal inertia of the semiconductor refrigeration chip 1 is very small, and the cooling and heating time is very fast. When the hot end dissipates heat well and the cold end is unloaded, the semiconductor refrigeration chip 1 can reach the maximum temperature difference in less than one minute after power is turned on. At this time, the temperature of the cooling end of the semiconductor refrigeration chip 1 can be about 30°C lower than the surrounding ambient temperature. The air in the switch cabinet passes through the cooling side of the semiconductor refrigeration chip 1 to produce condensation, which then condenses to form condensed water and is discharged from the pipeline to keep the inside of the switch cabinet dry.

[0042] Detection state: When the common end of switches K1A and K1B is connected to the normally closed contact, the refrigeration circuit of the semiconductor refrigeration film 1 is disconnected, and the semiconductor refrigeration film 1 stops refrigeration. Due to the temperature difference on both sides of the semiconductor refrigeration film, the Seebeck effect forms a reverse conversion of temperature difference-voltage. The Seebeck effect of the semiconductor refrigeration film 1 can be from hundreds of microvolts / ℃ to tens of millivolts / ℃. After a period of normal operation, the temperature difference between the cooling end and the heating end of the semiconductor refrigeration film 1 can reach 50-60℃, and then a temperature difference voltage Ua of more than hundreds of millivolts is formed at both ends of the semiconductor refrigeration film 1, which is in a detectable state.

[0043] The semiconductor refrigeration chip 1 has very small thermal inertia. After the working current is removed, the thermal equilibrium will be quickly restored, and Ua will converge from the maximum value to 0. Therefore, it is necessary to collect the temperature difference voltage Ua of the semiconductor refrigeration chip 1 as soon as possible when the switches K1A and K1B are disconnected to ensure the accuracy of the test.

[0044] The temperature difference voltage Ua passes through the first voltage detection circuit 2 to output a first detection signal Uc which is input to the controller 3 .

[0045] When the detection is completed, if the test is normal, the refrigeration circuit is closed and the refrigeration state is restored. The time span of shutting down the entire refrigeration circuit is defined as the detection period. The controller 3 detects the temperature difference voltage Ua within a narrow detection period or at the beginning of the detection period, preferably within 1 second at the beginning of the detection period.

[0046] The use of a double-group linkage switch can completely disconnect the refrigeration circuit of the semiconductor refrigeration plate 1 and accurately measure the temperature difference voltage Ua of the semiconductor refrigeration plate 1. However, the selection of the double-group linkage switch is not easy, or it needs to be combined through multiple single switches, which is costly and the circuit is complex. Therefore, the circuit needs to be further optimized.

[0047] like Figure 2 As shown, a block diagram of an online voltage detection circuit of a semiconductor refrigeration plate of a preferred embodiment of the present invention. Figure 3 yes Figure 2 Schematic diagram of the online voltage detection circuit of the further optimized semiconductor refrigeration piece.

[0048] In this preferred embodiment, it includes a semiconductor refrigeration sheet 1, a switch K2, a first voltage detection circuit 2 and a controller 3. The first end of the semiconductor refrigeration sheet 1 is connected to the positive electrode VDD of the power supply, the second end of the semiconductor refrigeration sheet 1 is connected to the negative electrode VSS of the power supply through the switch K2, the second end of the semiconductor refrigeration sheet 1 is connected to the first input end of the first voltage detection circuit 2, and the test signal Ub at the second end of the semiconductor refrigeration sheet 1 outputs a first detection signal Uc after passing through the first voltage detection circuit 2.

[0049] In this embodiment, the first voltage detection circuit 2 is a resistor voltage divider circuit, specifically, including resistors R1 and R2. The voltage detection output signal is connected to the second end of the semiconductor refrigeration plate 1 through the resistor R1, and is connected to the negative electrode of the power supply VSS through the resistor R2. The temperature difference voltage signal is input to the analog input end of the controller 4.

[0050] In terms of parameters, the sum of the resistance values ​​of resistors R3 and R4 is much larger than the internal resistance Rs of the semiconductor refrigeration plate 1 , and the internal resistance of the semiconductor refrigeration plate 1 is generally tens of mΩ to several Ω.

[0051] When the semiconductor refrigeration plate 1 is in the cooling state, the switch K2 is turned on, and the signal to be measured Ub at the second end of the semiconductor refrigeration plate 1 is the voltage drop of the switch K2, and the signal to be measured Ub is approximately equal to 0. When the switch K2 is turned off, the current flows to the detection circuit, and the current flows from the positive electrode of the power supply VDD through the semiconductor refrigeration plate 1, the resistor R1 and the resistor R2 to the negative electrode of the power supply VSS. The current is at most a few mA. The temperature difference voltage Ua generated by the Seebeck effect of the semiconductor refrigeration plate 1 can reach hundreds of mV or even more than 1V. The voltage drop Vs based on the internal resistance Rs can be ignored. It can be considered that the voltage Ub at the second end of the semiconductor refrigeration plate 1 is VDD-Ua, and the first detection signal Uc is output after passing through the first voltage detection circuit 2. Ua=VDD-Ub=VDD-Uc*(R1+R2) / R2 can be obtained through Uc.

[0052] When the semiconductor refrigeration chip is in the cooling state, the power supply outputs a large current; when the semiconductor refrigeration chip is in the detection state, the power supply outputs a small current. Due to the load change, the positive electrode VDD of the power supply will fluctuate, affecting the measurement accuracy. Therefore, the second voltage detection circuit 4 is added to collect the power supply voltage and obtain the second detection signal Up, Up = VDD * R4 / (R3 + R4). In order to facilitate the comparison and calculation of the second voltage detection circuit 4 and the first voltage detection circuit 2, the second voltage detection circuit 4 and the first voltage detection circuit 2 have the same voltage division ratio. At this time, Ua = Up * (R3 + R4) / R4-Uc * (R1 + R2) / R2 = (Up-Uc) * (R1 + R2) / R2.

[0053] Parameters of the specific embodiment:

[0054] Parameters of semiconductor refrigeration chip:

[0055] model Current Voltage Cooling capacity Temperature difference Dimensions TypeNumber Imax(A) Umax(V) Qcmax(W) ΔTmax(℃) Dimensions(mm) TEC-12703 3 12 18 60 40*40*3.6

[0056] R1, R3: 100kΩ

[0057] R2, R4: 50kΩ

[0058] Up=VDD*R4 / (R3+R4)=12*50 / (100+50)=4V.

[0059] The output terminal COLD of the controller 3 outputs a detection signal to the switch K2. After the switch K2 disconnects the refrigeration circuit of the semiconductor refrigeration plate 1, the controller 3 starts to collect the first detection signal Uc and the second detection signal Up, and compares them with the threshold list set in the controller 1, and then confirms whether the semiconductor refrigeration plate 1 is working abnormally. When the controller 1 completes the temperature difference voltage collection, the controller 1 controls the switch K2 to conduct, and reconnects the semiconductor refrigeration plate 1 to the refrigeration circuit. The entire detection process only takes a short time, which can be 1 second or several milliseconds, and the refrigeration of the semiconductor refrigeration plate 1 will not be affected at all. The temperature difference voltage Ua of the semiconductor refrigeration plate 1 can generally last for several seconds. In order to provide a quick response, the switch is preferably a semiconductor switch, such as a MOS tube, a power transistor, etc. At low power, that is, when the working current of the semiconductor refrigeration plate is not greater than 1A, it can be a power transistor; at high power, that is, when the working current of the semiconductor refrigeration plate is greater than 1A, it is preferably a MOS tube. The controller 1 can quickly disconnect or conduct the refrigeration circuit of the semiconductor refrigeration plate 1 by controlling the semiconductor switch. Of course, it is also possible to use mechanical switches such as relays, but the time required for opening and closing the switch is long, which affects the sampling accuracy of the temperature difference voltage to a certain extent. At the same time, mechanical switches have problems such as large size, short life and large driving current.

[0060] Figure 4 yes Figure 3 The test waveform diagram of the circuit, where S1 is the power waveform curve, S2 is the waveform curve of the signal to be tested Ub, and S3 is the waveform curve of the temperature difference voltage Ua, where S3 = S1-S2.

[0061] like Figure 5 The control flow shown is specifically applied to Figure 2 The detection circuit.

[0062] The output terminal COLD of the controller 1 outputs a control signal for controlling the closing or closing of the switch K2. The controller 1 turns on the refrigeration circuit of the semiconductor refrigeration plate 1 through the output terminal COLD output control signal. After the semiconductor refrigeration plate 1 works for a period of time, it is expected that the two sides of the semiconductor refrigeration plate 1 have reached the maximum temperature difference. The controller 3 can detect the temperature difference voltage Ua. The specific detection process includes

[0063] Step S1, control switch K2 to disconnect the refrigeration circuit of the semiconductor refrigeration plate;

[0064] Step S2, collecting the first detection signal Uc output by the first voltage detection circuit 2;

[0065] Step S3, comparing the first detection signal Uc with the internal threshold to determine the working state of the semiconductor refrigeration sheet 1;

[0066] Step S4, when it is determined that the working state of the semiconductor refrigeration piece 1 is normal, jump to step 5; when it is determined that the working state of the semiconductor refrigeration piece 1 is abnormal, jump to the abnormality handling procedure S6;

[0067] Step S5, controlling the switch K2 to close the refrigeration circuit of the semiconductor refrigeration plate.

[0068] Preferably, Figure 6 As shown, it is specifically applied to Figure 3 control flow.

[0069] Figure 3 Compared to Figure 2 A second voltage detection circuit 4 is added to output a second detection signal Up for detecting the power supply voltage. The second voltage detection circuit 4 and the first voltage detection circuit 2 have the same voltage division ratio.

[0070] The specific detection process includes the following steps:

[0071] Step S1, control switch K2 to disconnect the refrigeration circuit of the semiconductor refrigeration plate;

[0072] Step S2', collecting the first detection signal Uc output by the first voltage detection circuit 2; collecting the second detection signal Up output by the second voltage detection circuit 4;

[0073] Step S3', judging the working state of the semiconductor refrigeration plate 1 by comparing the difference between the first detection signal Uc and the second detection signal Up;

[0074] Step S4, when it is determined that the working state of the semiconductor refrigeration piece 1 is normal, jump to step 5; when it is determined that the working state of the semiconductor refrigeration piece 1 is abnormal, jump to the abnormality handling procedure S6;

[0075] Step S5, controlling the switch K2 to close the refrigeration circuit of the semiconductor refrigeration plate.

[0076] The exception handling procedure S6 includes but is not limited to status indication, sound warning, remote alarm information sending, power off, etc. These exception handling methods are also conventional processing methods of conventional monitoring and indication devices, and will not be described in detail here.

[0077] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. An online monitoring circuit for a semiconductor refrigeration chip, comprising a semiconductor refrigeration chip, characterized in that: Also includes a switch element, a first voltage detection circuit and a controller; The semiconductor refrigeration chip is connected to a power source to form a refrigeration and heating circuit, and the semiconductor refrigeration chip is connected to a first voltage detection circuit to form a detection circuit; The switch element is connected in series with the cooling and heating circuit, and is used to respond to the command of the controller to turn off or close the cooling and heating circuit; The first voltage detection circuit is used to detect the voltage change on the semiconductor refrigeration chip and output a first detection signal to the controller; The controller is used to: temporarily shut down the cooling and heating circuit when the semiconductor refrigeration chip is working, switch the working state of the semiconductor refrigeration chip from the cooling state to the detection state, and read the first detection signal when the semiconductor refrigeration chip is in the detection state, and judge the working state of the semiconductor refrigeration chip according to the first detection signal; After detecting that the semiconductor refrigeration piece is normal, the refrigeration and heating circuit is opened, and the state of the semiconductor refrigeration piece is switched from the detection state to the refrigeration state.

2. The online monitoring circuit of the semiconductor refrigeration sheet according to claim 1, characterized in that: The switch element is a double-group linkage switch, and the switch element includes a first common terminal, a first normally open terminal, a first normally closed terminal, a second common terminal, a second normally open terminal, and a second normally closed terminal. The positive and negative poles of the power supply are respectively connected to the first normally open terminal and the second normally open terminal; the two input terminals of the detection circuit are respectively connected to the first normally closed terminal and the second normally closed terminal; the two ends of the semiconductor refrigeration plate are respectively connected to the first common terminal and the second common terminal; the switch element is used to switch the semiconductor refrigeration plate to be only connected to the cooling and heating circuit or only connected to the detection circuit.

3. The online monitoring circuit of the semiconductor refrigeration sheet according to claim 1, characterized in that: The switch element and the semiconductor refrigeration plate are connected in series and connected to a power supply to form a cooling and heating circuit; the first voltage detection circuit is connected in parallel to both ends of the switch element; the semiconductor refrigeration plate and the first voltage detection circuit are connected in series and connected to a power supply to form a detection circuit.

4. The online monitoring circuit of the semiconductor refrigeration sheet as claimed in claim 3, characterized in that: The first end of the semiconductor refrigeration sheet is connected to the positive electrode of the power supply, and the second end of the semiconductor refrigeration sheet is connected to the negative electrode of the power supply through a switching element.

5. The online monitoring circuit of the semiconductor refrigeration sheet as claimed in claim 4, characterized in that: It also includes a second voltage detection circuit, which is used to detect the voltage of the power supply and output a second detection signal to the controller.

6. The online monitoring circuit of the semiconductor refrigeration sheet as claimed in claim 3, 4 or 5, characterized in that: The switch element is a MOS tube.

7. The online monitoring circuit of the semiconductor refrigeration sheet as claimed in claim 3, 4 or 5, characterized in that: The first voltage detection circuit is a resistor voltage divider circuit.

8. The online monitoring circuit of the semiconductor refrigeration sheet according to claim 1, characterized in that: The controller reads the first detection signal within 1 second after the semiconductor refrigeration plate is switched to the detection state.

9. The monitoring method of the online monitoring circuit of the semiconductor refrigeration chip according to claim 1, characterized in that: The controller executes a control program, comprising the steps of: Step S1, disconnecting the cooling and heating circuit of the semiconductor refrigeration plate, and switching the working state of the semiconductor refrigeration plate from the cooling state to the detection state; Step S2, after the semiconductor refrigeration chip is switched to the detection state, collecting a first detection signal output by a first voltage detection circuit; Step S3, comparing the first detection signal with the internal threshold value to determine whether the working state of the semiconductor refrigeration chip is normal; Step S4, when it is determined that the working state of the semiconductor refrigeration plate is normal, jump to step S5; When it is determined that the working state of the semiconductor refrigeration piece is abnormal, jump to the abnormality handling procedure S6; Step S5, closing the cooling and heating circuit of the semiconductor refrigeration plate, and switching the working state of the semiconductor refrigeration plate from the detection state to the cooling state.

10. The monitoring method of the online monitoring circuit of the semiconductor refrigeration chip according to claim 9, characterized in that: The controller further comprises a second input terminal, wherein the second input terminal is used to input a second detection signal; The online monitoring circuit of the semiconductor refrigeration plate also includes a second voltage detection circuit, which is used to detect the voltage of the power supply and output a second detection signal to the controller; The step S2 is changed to step S2': after the semiconductor refrigeration plate is switched to the detection state, collecting the first detection signal output by the first voltage detection circuit; collecting the second detection signal output by the second voltage detection circuit; The step S3 is changed to step S3': judging whether the working state of the semiconductor refrigeration plate is normal or not by the difference between the first detection signal and the second detection signal.

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