Temperature control alarm circuit with self-recovery function

Abstract

The utility model relates to the technical field of industrial safety temperature monitoring, in particular to a temperature control alarm circuit with a self-recovery function, which comprises a reference voltage module used for providing working voltage required by a temperature acquisition module and a signal hysteresis comparison module; the temperature acquisition module is used for acquiring a temperature signal and converting the acquired temperature signal into a voltage signal; the signal conditioning module is used for enhancing the voltage signal of the temperature acquisition module; the signal hysteresis comparison module is used for comparing the voltage signal enhanced by the signal conditioning module with a voltage value corresponding to a set temperature threshold value and expressing a comparison result in a logic level mode; and the temperature alarm module is used for completing the operation of sending or canceling a temperature control alarm according to the logic level output by the signal hysteresis comparison module.

Description

Technical Field

[0001] The utility model relates to the technical field of industrial safety temperature monitoring, in particular to a temperature control alarm circuit with a self-recovery function. Background Art

[0002] With the increasing attention paid to environmental protection and sustainable development around the world, the new energy industry has ushered in unprecedented development opportunities, especially in core areas such as power batteries and energy storage products, whose application scope has rapidly expanded to multiple key markets such as electric vehicles, smart grids, and portable power supplies. However, with the vigorous development of the new energy product market, product safety issues have gradually become prominent, becoming a key factor restricting the further healthy development of the industry. According to the latest statistics, new energy vehicles have frequent spontaneous combustion incidents, with an average of more than 7 vehicles catching fire due to various reasons every day. This severe situation not only poses huge safety risks to consumers, but also poses a serious challenge to corporate brand image and market confidence.

[0003] In this context, how to effectively improve the safety performance of new energy products and reduce safety accidents caused by overheating, short circuits and other factors has become a common focus of the government, enterprises and scientific research institutions. Traditionally, temperature monitoring, as an important technical means in the field of industrial safety, can prevent accidents caused by overheating of components to a certain extent, but it has limitations such as high false alarm rate of temperature information and rigid over-temperature threshold setting, making it difficult to accurately respond to complex and changing operating environments.

[0004] In order to overcome the above technical bottlenecks, the market urgently needs a temperature control alarm circuit with a self-recovery function. Utility Model Content

[0005] In view of the above technical problems, the utility model provides a temperature control alarm circuit with a self-recovery function.

[0006] The technical solution of the utility model to solve the above technical problems is as follows:

[0007] A temperature control alarm circuit with a self-recovery function comprises a voltage-stabilizing power supply module, a reference voltage module, a temperature sampling module, a signal conditioning module, a signal hysteresis comparison module and a temperature alarm module; the input end of the voltage-stabilizing power supply module is connected to an input voltage, the output end of the reference voltage module is respectively connected to the input end of the temperature sampling module and the input end of the signal hysteresis comparison module, the output end of the temperature sampling module is connected to the input end of the signal conditioning module, the output end of the signal conditioning module is connected to the input end of the signal hysteresis comparison module, and the output end of the signal hysteresis comparison module is connected to the input end of the temperature control alarm module;

[0008] The regulated power supply module is used to provide the working voltage for each circuit; the reference voltage module is used to provide the working voltage required by the temperature acquisition module and the signal hysteresis comparison module; the temperature acquisition module is used to acquire temperature signals and convert the acquired temperature signals into voltage signals; the signal conditioning module is used to enhance the voltage signals of the temperature acquisition module; the signal hysteresis comparison module is used to compare the voltage signals enhanced by the signal conditioning module with the voltage values corresponding to the set temperature thresholds, and present the comparison results in the form of logic levels; the temperature alarm module is used to complete the operation of sending or canceling the temperature control warning according to the logic levels output by the signal hysteresis comparison module.

[0009] The beneficial effects of adopting the above technical solution are as follows: The reference voltage module receives the stable voltage provided by the regulated power supply module and is respectively connected to the input ends of the temperature sampling module and the signal hysteresis comparison module. The reference voltage module provides a stable voltage reference for them to ensure the accuracy of temperature measurement and signal comparison; the temperature sampling module converts the acquired temperature signals into voltage signals and outputs them to the input end of the signal conditioning module; the signal conditioning module receives the voltage signals output by the temperature sampling module, processes the input voltage signals to enhance the anti-interference ability of the signals, and then outputs the processed signals to the input end of the signal hysteresis comparison module; the signal hysteresis comparison module receives the voltage signals from the signal conditioning module and the reference voltage from the reference voltage module, which is used to set the voltage values corresponding to the too-high temperature threshold and the normal temperature threshold, compares the processed voltage signals with the set thresholds, and outputs a logic level signal to the input end of the temperature control alarm module according to the comparison results; the temperature control alarm module receives the logic level signal output by the signal hysteresis comparison module and completes the operation of sending or canceling the temperature control warning.

[0010] Based on the above technical solution, the following improvements can be made to the above technical solution:

[0011] Further, the reference voltage module includes a first reference voltage module and a second reference voltage module. The first reference voltage module is used to provide a working voltage reference for the temperature acquisition module; the second reference voltage module is used to provide a working voltage reference for the signal hysteresis comparison module.

[0012] The beneficial effects of adopting the above further technical solution are as follows: The first reference voltage module provides a working voltage reference for the temperature acquisition module. When the temperature acquisition module converts the temperature signals into voltage signals, it uses the stable voltage provided by the first reference voltage module as a reference to ensure the accuracy and consistency of the conversion. The second reference voltage module provides a working voltage reference for the signal hysteresis comparison module. When the signal hysteresis comparison module performs signal comparison, it needs a reference voltage as the threshold voltage to determine when to trigger an alarm, and the second reference voltage module provides the reference voltage for the signal hysteresis comparison module.

[0013] Further, the first reference voltage module includes a reference voltage chip, a first resistor, a second resistor, and a third resistor; the output end of the regulated power supply module is connected to one end of the first resistor, and the other end of the first resistor is respectively connected to one end of the second resistor and the negative pole of the reference voltage chip, serving as the output end of the reference voltage module. The other end of the second resistor is respectively connected to the third resistor and the reference base of the reference voltage chip, and the other end of the third resistor, the positive pole of the reference voltage chip are connected to the isolated reference ground.

[0014] The beneficial effect of adopting the above further technical solution is that the output end of the regulated power supply module is connected to one end of the first resistor to provide a stable power supply voltage; the other end of the first resistor is respectively connected to one end of the second resistor and the negative pole of the reference voltage chip. The first resistor is used to provide driving current, and the second resistor and the third resistor together form a voltage divider for dividing the power supply voltage; the other end of the second resistor is connected to the reference base of the reference voltage chip and one end of the third resistor; the reference voltage chip adjusts its internal circuit to keep a constant voltage value at its reference base all the time. The output end of the reference voltage module obtains the reference voltage according to the voltage division ratio of the second resistor and the third resistor; the other end of the third resistor and the positive pole of the reference voltage chip are both connected to the isolated reference ground, and the isolated reference ground is to ensure the purity and stability of the reference voltage and avoid external noise and interference.

[0015] Further, the temperature sampling module includes a negative temperature coefficient thermistor, a fourth resistor, a first ceramic capacitor, and a second ceramic capacitor; the output end of the first reference voltage module is respectively connected to one end of the thermistor and one end of the first ceramic capacitor. The other end of the thermistor, the other end of the first ceramic capacitor are respectively connected to one end of the fourth resistor and the second ceramic capacitor, serving as the output end of the temperature sampling module. The other end of the fourth resistor, the other end of the second ceramic capacitor are connected to the isolated reference ground.

[0016] The beneficial effect of adopting the above further technical solution is that the thermistor, the fourth resistor, the first capacitor, and the second capacitor form a voltage division circuit to output a voltage related to temperature. When the temperature changes, the resistance value of the thermistor will change accordingly; since the resistance value of the fourth resistor is fixed, the output voltage of the voltage division circuit, that is, the output voltage of the temperature sampling module, will also change with the change of the resistance value of the thermistor. This voltage signal can then be further processed by the signal conditioning module and finally used for temperature measurement or control.

[0017] Further, the signal conditioning module includes an operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; the output end of the temperature sampling module is connected to one end of the seventh resistor, and the other end of the seventh resistor is respectively connected to the non-inverting input end of the operational amplifier and one end of the eighth resistor, and the other end of the eighth resistor is connected to the isolated reference ground; one end of the fifth resistor is connected to the isolated reference ground, and the other end of the fifth resistor is respectively connected to the inverting input end of the operational amplifier and one end of the sixth resistor, and the other end of the sixth resistor is connected to the voltage output end of the operational amplifier and serves as the output end of the signal conditioning module; the output end of the regulated power supply module is connected to the positive power supply end of the operational amplifier, and the negative power supply end of the operational amplifier is connected to the isolated reference ground, where the resistance value of the fifth resistor is the same as that of the seventh resistor, and the resistance values of the sixth resistor and the eighth resistor are the same.

[0018] The beneficial effect of adopting the above further technical solution is that when the voltage signal output by the temperature sampling module enters the non-inverting input end of the operational amplifier through the seventh resistor and the eighth resistor, the operational amplifier will subtract it from the reference potential at the inverting input end, and form a feedback network through the fifth (seventh) resistor and the sixth (eighth) resistor to form a non-inverting proportional operation circuit, which conditions the input signal proportionally. The operational amplifier also acts as a voltage follower, playing the role of isolation and anti-interference.

[0019] Further, the signal hysteresis comparison module includes a voltage comparator, a Schottky diode, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor; the output end of the signal conditioning module is connected to one end of the tenth resistor, and the other end of the tenth resistor is connected to the negative input of the voltage comparator. The second reference voltage module outputs a reference voltage value and is connected to one end of the ninth resistor. The other end of the ninth resistor is respectively connected to the positive input end of the voltage comparator and one end of the eleventh resistor. The other end of the eleventh resistor is respectively connected to the output end of the voltage comparator, one end of the twelfth resistor, and the negative electrode of the Schottky diode. The other end of the twelfth resistor is respectively connected to the output end of the regulated power supply module and one end of the thirteenth resistor. The other end of the thirteenth resistor is connected to the positive electrode of the Schottky diode and serves as the output end of the hysteresis comparison module.

[0020] The beneficial effect of adopting the above further technical solution is that the voltage comparator compares the signal output by the signal conditioning module with the reference voltage value output by the second reference voltage module, uses the Schottky diode, the twelfth resistor, and the thirteenth resistor to achieve the hysteresis function, forms a temperature window in a small interval by using the proportional relationship formed by the ninth resistor and the eleventh resistor, and uses the high and low temperature points in the interval to flip twice to represent the logic level, playing the role of eliminating short-term high-temperature false alarms and self-recovery. The result output is a logic level signal; the twelfth resistor and the thirteenth resistor serve as pull-up resistors to make the default logic level signal high level.

[0021] Further, the temperature alarm module includes a photoelectric coupler, a fourteenth resistor, and a fifteenth resistor; the output end of the signal hysteresis comparison module is connected to one end of the fourteenth resistor, the other end of the fourteenth resistor is connected to the cathode of the photoelectric coupler, the anode of the photoelectric coupler is connected to the output end of the regulated power supply module, the emitter of the photoelectric coupler is connected to the analog ground, the second input voltage is connected to one end of the fifteenth resistor, and the other end of the fifteenth resistor is connected to the collector of the photoelectric coupler and serves as an alarm signal.

[0022] The beneficial effect of adopting the above further technical solution is that when the signal hysteresis comparison module detects an abnormal temperature condition, the signal hysteresis comparison module outputs a low level; the low-level signal reaches the cathode of the photoelectric coupler after being limited in current by the fourteenth resistor; the internal photoelectric effect of the photoelectric coupler causes the collector current to increase and the collector potential to decrease; the decrease in the collector potential triggers an alarm signal. When the temperature returns to normal and the output of the signal hysteresis comparison module is high, the photoelectric coupler is cut off, the collector potential is restored, and the alarm signal is cancelled.

[0023] In summary, compared with the prior art, the present utility model has the following technical effects:

[0024] The present utility model provides a temperature control alarm circuit with a self-recovery function, which ensures the temperature monitoring sensitivity, effectively eliminates false alarms caused by short-term overheating, and has the function of automatically canceling the alarm. There is no need for a dedicated temperature monitoring chip or a dedicated temperature comparator chip, which saves the cost of circuit design and realizes effective electrical isolation between each temperature monitoring working circuit and the main control IC. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the principle block diagram of the present utility model;

[0026] Figure 2 is the principle circuit diagram of the reference voltage module of the present utility model;

[0027] Figure 3 is the principle circuit diagram of the temperature sampling module of the present utility model;

[0028] Figure 4 is the principle circuit diagram of the signal conditioning module of the present utility model;

[0029] Figure 5 is the principle circuit diagram of the signal hysteresis comparison module of the present utility model;

[0030] Figure 6 is the principle circuit diagram of the temperature alarm module of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The principles and features of the present utility model will be described below in conjunction with the accompanying drawings. The examples given are only for explaining the present utility model and are not intended to limit the scope of the present utility model.

[0032] Referring to Figure 1 , a temperature control alarm circuit with self - recovery function, includes a regulated power supply module, a reference voltage module, a temperature sampling module, a signal conditioning module, a signal hysteresis comparison module and a temperature alarm module; the regulated power supply module is used to provide the working voltage for each loop; the reference voltage module is used to provide the working voltage required by the temperature acquisition module and the signal hysteresis comparison module; the temperature acquisition module is used to collect temperature signals and convert the collected temperature signals into voltage signals; the signal conditioning module is used to enhance the voltage signal of the temperature acquisition module; the signal hysteresis comparison module is used to compare the voltage signal enhanced by the signal conditioning module with the voltage value corresponding to the set temperature threshold and present the comparison result in the form of logic levels; the temperature alarm module is used to complete the operation of sending or canceling the temperature control warning according to the logic level output by the signal hysteresis comparison module.

[0033] In this embodiment, the regulated power supply module is used to provide a stable working voltage for the entire circuit.

[0034] Specifically, the input end of the regulated power supply module is connected to the input alternating current, and a stable direct - current power supply VIN1 is output, specifically 5V direct current is output; the output end of the reference voltage module is respectively connected to the input end of the temperature sampling module and the input end of the signal hysteresis comparison module, the output end of the temperature sampling module is connected to the input end of the signal conditioning module, the output end of the signal conditioning module is connected to the input end of the signal hysteresis comparison module, and the output end of the signal hysteresis comparison module is connected to the input end of the temperature control alarm module. Among them, the model of the regulated power supply module is DH1718E.

[0035] The reference voltage module receives the stable voltage provided by the regulated power supply module and is respectively connected to the input ends of the temperature sampling module and the signal hysteresis comparison module. The reference voltage module provides a stable voltage reference for them to ensure the accuracy of temperature measurement and signal comparison. The temperature sampling module converts the collected temperature signal into a voltage signal and outputs it to the input end of the signal conditioning module. The signal conditioning module receives the voltage signal output by the temperature sampling module, processes the input voltage signal to enhance the anti-interference ability of the signal, and then outputs the processed signal to the input end of the signal hysteresis comparison module. The signal hysteresis comparison module receives the voltage signal from the signal conditioning module and the reference voltage from the reference voltage module, which is used to set the voltage value corresponding to the temperature threshold, compares the processed voltage signal with the set threshold, and outputs a logic level signal to the input end of the temperature control alarm module according to the comparison result. The temperature control alarm module receives the logic level signal output by the signal hysteresis comparison module and completes the operation of sending or canceling the temperature control warning.

[0036] In this embodiment, the reference voltage module includes a first reference voltage module and a second reference voltage module. The first reference voltage module is used to provide a stable working voltage reference for the temperature acquisition module; the first reference voltage module is used to provide a stable working voltage reference for the signal hysteresis comparison module.

[0037] Specifically, referring to FIG. Figure 2 , the first reference voltage module includes a reference voltage chip D1, a first resistor R1, a second resistor R2, and a third resistor R3. The first resistor R1, the second resistor R2, and the third resistor R3 are all precision resistors. One end of the output terminal VIN1 of the regulated power supply module is connected to one end of the first resistor R1. The other end of the first resistor R1 is respectively connected to one end of the second resistor R2 and the negative electrode of the reference voltage chip D1, serving as the output terminal Vref1 of the reference voltage module. The other end of the second resistor R2 is respectively connected to the third resistor R3 and the reference base of the reference voltage chip D1. The other end of the third resistor R3, the positive electrode of the reference voltage chip D1 are connected to the isolated reference ground.

[0038] The output terminal of the regulated power supply module is connected to one end of the first resistor R1 to provide a stable power supply voltage; the other end of the first resistor R1 is respectively connected to one end of the second resistor R2 and the negative electrode of the reference voltage chip D1. The first resistor R1 is used to provide a driving current. The second resistor R2 and the third resistor R3 together form a voltage divider for dividing the power supply voltage; the other end of the second resistor R2 is connected to the reference base of the reference voltage chip D1 and one end of the third resistor R3; the reference voltage chip adjusts its internal circuit to keep a constant voltage value at its reference base all the time. The output terminal of the reference voltage module obtains the reference voltage according to the voltage division ratio of the second resistor R2 and the third resistor R3; the other end of the third resistor R3 and the positive electrode of the reference voltage chip are both connected to the isolated reference ground, and the isolated reference ground is to ensure the purity and stability of the reference voltage and avoid external noise and interference.

[0039] The circuit principle structure of the second reference voltage module is the same as that of the first reference voltage module, and the difference lies in that the output reference voltage value Vref2 is different, which will not be elaborated here.

[0040] In this embodiment, the temperature sampling module uses a negative temperature coefficient thermistor RT1 to sense the temperature and convert it into a voltage signal. The thermistor RT1, the fourth resistor R4, the first capacitor C1, and the second capacitor C2 form a voltage division circuit to output a temperature-related voltage Vtemp.

[0041] Specifically, referring to Figure 3 , the temperature sampling module includes a negative temperature coefficient thermistor RT1, a fourth resistor R4, a first ceramic capacitor C1, and a second ceramic capacitor C2. The fourth resistor R4 is a precision resistor; the output terminal Vref1 of the first reference voltage module is respectively connected to one end of the thermistor RT1 and one end of the first ceramic capacitor C1. The other end of the thermistor RT1 and the other end of the first ceramic capacitor C1 are respectively connected to one end of the fourth resistor R4 and the second ceramic capacitor C2 as the output terminal Vtemp of the temperature sampling module. The other end of the fourth resistor R4 and the other end of the second ceramic capacitor C2 are connected to the isolated reference ground.

[0042] The output terminal Vref1 of the first reference voltage module is respectively connected to one end of the thermistor RT1 and one end of the first ceramic capacitor C1, providing a stable reference voltage for the entire voltage division circuit; the other end of the thermistor RT1 is connected to the other end of the first ceramic capacitor C1 and one end of the fourth resistor R4, constituting a part of the voltage division circuit; the other end of the fourth resistor R4 is connected to one end of the second ceramic capacitor C2 and the isolated reference ground, serving as the output terminal of the temperature sampling module; the fourth resistor R4 and the negative temperature coefficient thermistor RT1 jointly divide the voltage provided by the first reference voltage module, outputting a voltage signal that varies with temperature; the other end of the second ceramic capacitor C2 is also connected to the isolated reference ground, used to filter out noise and interference in the output signal.

[0043] When the temperature changes, the resistance value of the thermistor RT1 will change accordingly; since the resistance value of the fourth resistor R4 is fixed, the output voltage of the voltage division circuit, that is, the output voltage of the temperature sampling module, will also change with the change of the resistance value of the thermistor RT1. This voltage signal can then be further processed by the signal conditioning module and ultimately used for temperature measurement or control.

[0044] In this embodiment, the signal conditioning module is used to enhance the quality of the voltage signal Vtemp and reduce external interference. Through an amplifier circuit composed of the operational amplifier D2, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8, Vtemp is amplified and filtered, and Vout1 is output.

[0045] Specifically, referring to Figure 4 , the signal conditioning module includes the operational amplifier D2, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8. The fifth resistor R5, the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8 are all precision resistors; the output terminal Vtemp of the temperature sampling module is connected to one end of the seventh resistor R7, and the other end of the seventh resistor R7 is respectively connected to the non-inverting input terminal of the operational amplifier D2 and one end of the eighth resistor R8. The other end of the eighth resistor R8 is connected to the isolated reference ground; one end of the fifth resistor R5 is connected to the isolated reference ground, and the other end of the fifth resistor R5 is respectively connected to the inverting input terminal of the operational amplifier D2 and one end of the sixth resistor R6. The other end of the sixth resistor R6 is connected to the voltage output terminal of the operational amplifier D2 and serves as the output terminal Vout1 of the signal conditioning module; the output terminal VIN1 of the regulated power supply module is connected to the positive power supply terminal of the operational amplifier D2, and the negative power supply terminal of the operational amplifier D2 is connected to the isolated reference ground. Among them, the operational amplifier D2 is a single-channel rail-to-rail output operational amplifier.

[0046] The output terminal Vtemp of the temperature sampling module is connected to one end of the seventh resistor R7, and the temperature sampling signal is sent to the signal conditioning module; the other end of the seventh resistor R7 is respectively connected to the non-inverting input terminal of the operational amplifier D2 and one end of the eighth resistor R8. The seventh resistor R7 and the eighth resistor R8 jointly determine the signal strength input to the non-inverting input terminal of the operational amplifier D2; the other end of the fifth resistor R5 is respectively connected to the inverting input terminal of the operational amplifier D2 and one end of the sixth resistor R6; the other end of the sixth resistor R6 is connected to the voltage output terminal of the operational amplifier D2 and serves as the output terminal of the signal conditioning module. The output terminal of the regulated power supply module is connected to the positive power supply terminal of the operational amplifier D2 to provide a stable positive power supply voltage for the operational amplifier D2.

[0047] When the voltage signal output by the temperature sampling module enters the non-inverting input terminal of the operational amplifier through the seventh resistor R7 and the eighth resistor R8, the operational amplifier will compare it with the reference potential at the inverting input terminal and adjust the output voltage through its internal circuit so that the potential at the inverting input terminal is equal to the potential at the non-inverting input terminal. Since the fifth resistor R5 and the sixth resistor R6 form a feedback network, the output voltage of the operational amplifier will be amplified (or attenuated). In this way, the temperature sampling signal is conditioned into a voltage signal more suitable for subsequent processing. Among them, the resistance value of the fifth resistor is the same as that of the seventh resistor, and the resistance values of the sixth resistor and the eighth resistor are the same.

[0048] In this embodiment, the signal hysteresis comparison module is used to detect the temperature threshold through hysteresis comparison to prevent misoperation. The voltage comparator D3 compares Vout1 with the reference voltage value output by the second reference voltage module, and uses the Schottky diode V1, the twelfth resistor R12, and the thirteenth resistor R13 to implement the hysteresis function, and the output Vout2 is a logic level signal.

[0049] Specifically, refer to Figure 5, the signal hysteresis comparison module includes a voltage comparator D3, a Schottky diode V1, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13. The ninth resistor R9, the tenth resistor R10, and the eleventh resistor R11 are all precision resistors, and the twelfth resistor R12 and the thirteenth resistor R13 are ordinary thick film resistors. The output terminal Vout1 of the signal conditioning module is connected to one end of the tenth resistor R10, the other end of the tenth resistor R10 is connected to the negative-phase input of the voltage comparator D3, the reference voltage value Vref2 output by the second reference voltage module is connected to one end of the ninth resistor R9, and the other end of the ninth resistor R9 is respectively connected to the positive-phase input terminal of the voltage comparator D3 and one end of the eleventh resistor R11. The other end of the eleventh resistor R11 is respectively connected to the output terminal of the voltage comparator D3, one end of the twelfth resistor R12, and the negative electrode of the Schottky diode V1. The other end of the twelfth resistor R12 is respectively connected to the output terminal VIN1 of the regulated power supply module and one end of the thirteenth resistor R13. The other end of the thirteenth resistor R13 is connected to the positive electrode of the Schottky diode V1 and serves as the output terminal Vout2 of the hysteresis comparison module.

[0050] The output signal Vout1 of the signal conditioning module is input to the negative-phase input terminal of the voltage comparator D3 through the tenth resistor R10. At the same time, the reference voltage value Vref2 output by the second reference voltage module is input to the positive-phase input terminal of the voltage comparator D3 through the ninth resistor R9. The voltage comparator D3 outputs a high-level or low-level signal according to the magnitude relationship between these two input voltages. When the input signal Vout1 changes, due to the forward voltage drop characteristic of the Schottky diode V1, the change of the output state of the voltage comparator D3 does not occur immediately, but remains unchanged within a small voltage range (determined jointly by the twelfth resistor R12, the thirteenth resistor R13, and the Schottky diode V1), thus realizing the hysteresis function and improving the anti-interference ability and stability of the circuit.

[0051] Among them, by adjusting the reference voltage value Vref2 output by the second reference voltage module and the proportional relationship between the ninth resistor R9 and the eleventh resistor R11, different temperature thresholds can be set.

[0052] When Vout1 increases to exceed the positive-phase input terminal threshold (i.e., the upper hysteresis threshold) obtained by dividing the voltage by the ninth resistor R9 and the eleventh resistor R11, the output of D3 flips from high level to low level. At this time, the Schottky diode V1 conducts, but since D3 has already output a low level, the impact of this state on the circuit is mainly reflected in that a higher Vout1 voltage is required to flip it back to a high level when keeping the output of D3 at a low level, that is, the upper hysteresis threshold is increased.

[0053] When Vout1 decreases and falls below the upper hysteresis threshold, D3 remains low. However, as Vout1 continues to decrease, the Schottky diode V1 turns off (since it no longer has enough forward voltage to conduct). At this time, the voltage at the non-inverting input terminal returns to the level determined only by the voltage division of the ninth resistor R9 and the eleventh resistor R11, which constitutes the lower hysteresis threshold, and the lower hysteresis threshold is lower than the upper hysteresis threshold.

[0054] Only when Vout1 decreases to exceed the lower hysteresis threshold will the output of D3 flip back from low to high. In this way, the circuit forms a hysteresis window, that is, a voltage range between the upper hysteresis threshold and the lower hysteresis threshold. Within this range, the output state of D3 will not change with small changes in Vout1. This design helps to reduce false alarms caused by short-term high-temperature fluctuations because the circuit requires a larger signal change to trigger a state change.

[0055] In this embodiment, the temperature alarm module controls the sending or cancellation of the alarm signal according to the output of the signal hysteresis comparison module. The alarm signal is isolated and driven through the optocoupler E1. When Vout2 is low, the optocoupler E1 conducts and outputs an alarm signal.

[0056] Specifically, referring to Figure 6 , the temperature alarm module includes an optocoupler E1, a fourteenth resistor R14, and a fifteenth resistor R15. The fourteenth resistor R14 and the fifteenth resistor R15 are ordinary thick film resistors; the output terminal Vout2 of the signal hysteresis comparison module is connected to one end of the fourteenth resistor R14, the other end of the fourteenth resistor R14 is connected to the cathode of the optocoupler E1, the anode of the optocoupler E1 is connected to the output terminal VIN1 of the regulated power supply module, the emitter of the optocoupler E1 is connected to the analog ground, one end of the fifteenth resistor R15 is connected to the output terminal VIN2 of the regulated power supply module, and the other end of the fifteenth resistor R15 is connected to the collector of the optocoupler E1 and serves as the alarm signal.

[0057] The optocoupler E1, as an electrical isolation component, is used to isolate the control signal (from Vout2) from the alarm signal output circuit. This can improve the safety and stability of the system and prevent high voltage or high current from interfering with the control circuit. The fourteenth resistor R14, as a current-limiting resistor, is connected between the output terminal Vout2 of the signal hysteresis comparison module and the cathode of the optocoupler E1. Its function is to limit the current flowing into the optocoupler E1 and prevent the device from being damaged due to excessive current. The fifteenth resistor R15 is connected between the input terminal VIN2 of the regulated power supply module and the collector of the optocoupler E1. When the optocoupler E1 is not conducting, the fifteenth resistor R15 can ensure that the collector has a definite level state, usually a high level. VIN1 provides power for the anode of the optocoupler E1, while VIN2 is used to supply power to other parts of the circuit. The alarm signal is output through the collector of the optocoupler E1.

[0058] When the signal hysteresis comparison module detects an abnormal temperature condition, Vout2 outputs a low level; the low-level signal reaches the cathode of the optocoupler E1 after being current-limited by the fourteenth resistor R14; the photoelectric effect inside the optocoupler E1 causes the collector current to increase and the collector potential to drop; the drop in the collector potential triggers the alarm signal, which may perform an audible and visual alarm or other operations through an external circuit (such as an LED). When the temperature returns to normal and Vout2 of the signal hysteresis comparison module outputs a high level, the optocoupler E1 is cut off, the collector potential is restored, and the alarm signal is cancelled.

[0059] In the present utility model, when the system starts, since the twelfth resistor R12 and the thirteenth resistor R13 act as pull-up resistors, the output of D3 defaults to a high level; when the temperature rises and causes Vout1 to increase beyond the upper hysteresis threshold, the output of D3 flips to a low level and the Schottky diode V1 conducts; if the temperature continues to rise or remains at a high level, D3 remains in the low-level state and the alarm signal is triggered.

[0060] When the temperature starts to drop and is lower than the upper hysteresis threshold, D3 still remains in the low-level state, but the Schottky diode V1 is cut off; when the temperature further drops below the lower hysteresis threshold, the output of D3 flips back to a high level, the alarm signal is cancelled, and the system returns to the normal state, waiting for the next possible abnormal temperature event.

[0061] The above are only the preferred embodiments of the present utility model and are not used to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A temperature-controlled warning circuit with self-recovery function, characterized in that, It includes a regulated power supply module, a reference voltage module, a temperature sampling module, a signal conditioning module, a signal hysteresis comparison module, and a temperature alarm module; the input end of the regulated power supply module is connected to the input voltage, the output end of the reference voltage module is respectively connected to the input end of the temperature sampling module and the input end of the signal hysteresis comparison module, the output end of the temperature sampling module is connected to the input end of the signal conditioning module, the output end of the signal conditioning module is connected to the input end of the signal hysteresis comparison module, and the output end of the signal hysteresis comparison module is connected to the input end of the temperature control alarm module; The regulated power supply module is used to provide the working voltage for each loop; the reference voltage module is used to provide the working voltage required for the temperature acquisition module and the signal hysteresis comparison module; the temperature acquisition module is used to collect temperature signals and convert the collected temperature signals into voltage signals; the signal conditioning module is used to enhance the voltage signals of the temperature acquisition module; the signal hysteresis comparison module is used to compare the enhanced voltage signals of the signal conditioning module with the voltage value corresponding to the set temperature threshold and present the comparison result in a logic level manner; The temperature alarm module is used to complete the operation of sending or canceling the temperature control warning according to the logic level output by the signal hysteresis comparison module.

2. The temperature control warning circuit with self - recovery function according to claim 1, wherein, The reference voltage module includes a first reference voltage module and a second reference voltage module. The first reference voltage module is used to provide a working voltage reference for the temperature acquisition module; the second reference voltage module is used to provide a working voltage reference for the signal hysteresis comparison module.

3. The temperature-controlled alarm circuit with self-recovery function according to claim 2, wherein The first reference voltage module includes a reference voltage chip, a first resistor, a second resistor, and a third resistor; the output end of the regulated power supply module is connected to one end of the first resistor, the other end of the first resistor is respectively connected to one end of the second resistor and the negative pole of the reference voltage chip as the output end of the reference voltage module, the other end of the second resistor is respectively connected to the third resistor and the reference base of the reference voltage chip, and the other end of the third resistor, the positive pole of the reference voltage chip are connected to the isolated reference ground.

4. The temperature control warning circuit with self - recovery function according to claim 3, characterized in that, The temperature sampling module includes a negative temperature coefficient thermistor, a fourth resistor, a first ceramic capacitor, and a second ceramic capacitor; the output end of the first reference voltage module is respectively connected to one end of the thermistor and one end of the first ceramic capacitor, the other end of the thermistor, the other end of the first ceramic capacitor are respectively connected to one end of the fourth resistor and the second ceramic capacitor as the output end of the temperature sampling module, and the other end of the fourth resistor, the other end of the second ceramic capacitor are connected to the isolated reference ground.

5. A temperature control warning circuit with a self - recovery function according to claim 4, characterized in that, The signal conditioning module includes an operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; the output end of the temperature sampling module is connected to one end of the seventh resistor, the other end of the seventh resistor is respectively connected to the non-inverting input end of the operational amplifier and one end of the eighth resistor, and the other end of the eighth resistor is connected to the isolated reference ground; One end of the fifth resistor is connected to the isolated reference ground. The other end of the fifth resistor is respectively connected to the inverting input terminal of the operational amplifier and one end of the sixth resistor. The other end of the sixth resistor is connected to the voltage output terminal of the operational amplifier and serves as the output terminal of the signal conditioning module. The output terminal of the regulated power supply module is connected to the positive power supply terminal of the operational amplifier, and the negative power supply terminal of the operational amplifier is connected to the isolated reference ground.

6. The temperature-controlled warning circuit with self-recovery function according to claim 5, characterized in that, The signal hysteresis comparison module includes a voltage comparator, a Schottky diode, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor. The output terminal of the signal conditioning module is connected to one end of the tenth resistor. The other end of the tenth resistor is connected to the negative input of the voltage comparator. The second reference voltage module outputs a reference voltage value and is connected to one end of the ninth resistor. The other end of the ninth resistor is respectively connected to the positive input terminal of the voltage comparator and one end of the eleventh resistor. The other end of the eleventh resistor is respectively connected to the output terminal of the voltage comparator, one end of the twelfth resistor, and the cathode of the Schottky diode. The other end of the twelfth resistor is respectively connected to the output terminal of the regulated power supply module and one end of the thirteenth resistor. The other end of the thirteenth resistor is connected to the anode of the Schottky diode and serves as the output terminal of the hysteresis comparison module.

7. A temperature control warning circuit with self - recovery function according to claim 6, characterized in that, The temperature alarm module includes an optocoupler, a fourteenth resistor, and a fifteenth resistor. The output terminal of the signal hysteresis comparison module is connected to one end of the fourteenth resistor. The other end of the fourteenth resistor is connected to the cathode of the optocoupler. The anode of the optocoupler is connected to the output terminal of the regulated power supply module. The emitter of the optocoupler is connected to the analog ground. The second input voltage is connected to one end of the fifteenth resistor. The other end of the fifteenth resistor is connected to the collector of the optocoupler and serves as the alarm signal.

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