Electric heating temperature control device and electric heating equipment

Abstract

The present application belongs to the field of temperature control, and in particular relates to an electric heating temperature control device and an electric heating equipment. The electric heating temperature control device is externally connected to an electric heating wire, which includes a temperature-sensing conductor, an insulating isolation layer, and a heating conductor. The electric heating temperature control device includes a temperature detection circuit, which includes a temperature-sensing voltage-dividing sampling unit, an AC voltage-dividing sampling unit, and a differential signal processing unit. The AC voltage-dividing sampling unit is used to convert the input signal of the AC power supply into a reference voltage signal, the temperature-sensing voltage-dividing sampling unit is used to convert the signal flowing through the temperature-sensing conductor into a temperature voltage signal, and the differential signal processing unit is used to perform differential comparison and identification processing on the temperature voltage signal and the reference voltage signal. The temperature detection circuit of the present application can suppress the error caused by the change in the AC power supply voltage, improve the accuracy of the temperature-sensing conductor in sensing temperature changes, and realize high-precision temperature detection of the temperature detection circuit.

Description

Technical Field

[0001] The present invention relates to the field of temperature control, and in particular to electric heating temperature control devices and electric heating equipment. Background Art

[0002] Currently, there are many types of traditional electric heating products, such as heating pads and electric blankets, both domestically and internationally, and correspondingly, a wide variety of temperature control circuits. Due to the suboptimal temperature control devices of existing electric blankets, existing electric blankets have several problems. These include local wrinkles that can cause localized high temperatures during use, leading to premature damage and even endangering the user's personal and property safety. These products also lack temperature detection or inaccurate temperature detection, impacting user comfort. Furthermore, these products lack comprehensive safety protection, resulting in a lack of reliable safety protection circuits when certain components in the circuit fail, causing the blanket to continue heating up, seriously impacting safety.

[0003] In order to solve the above-mentioned problem of local high temperature caused by the use of local wrinkles, the British invented an electric heating wire, which consists of a two-level conductor and a temperature-sensitive layer with negative temperature coefficient (NTC) characteristics arranged between the two-level conductors (hereinafter referred to as the NTC temperature-sensitive layer). One of the first-level conductors of the heating wire has a positive temperature coefficient (PTC) characteristic (hereinafter referred to as the PTC conductor); the current technical control circuit uses the NTC temperature-sensitive layer for local temperature detection and high-temperature safety protection, and uses the PTC conductor for overall temperature detection. In theory, it can prevent local high temperature caused by the use of local wrinkles in the electric blanket, and achieve high-precision temperature control. Temperature detection and temperature control; however, the temperature sensing error of the NTC temperature sensing layer of the current technology is as high as plus or minus 30%, and its temperature coefficient will age and change over time as the electric blanket is used; and when the current technology temperature control circuit detects the temperature of the PTC conductor, leakage will occur between the PTC conductor and the NTC temperature sensing layer. Therefore, a very unstable leakage current will be generated between the PTC conductor and the NTC temperature sensing layer, which will seriously affect the accuracy of temperature detection; in addition, the current technology temperature control circuit will also affect the accuracy of temperature detection due to fluctuations in the AC power supply voltage. Therefore, the current technology temperature detection is not accurate.

[0004] Therefore, how to achieve accurate temperature detection and control and to provide a temperature control circuit that can provide safety protection when a circuit failure causes temperature loss or improper use causes local or overall high temperatures is an urgent problem that needs to be solved. Summary of the Invention

[0005] The main purpose of this application is to provide an electric heating temperature control device and an electric heating equipment, aiming to solve the technical problem that the temperature detection of traditional electric heating temperature control devices is not accurate enough.

[0006] A first aspect of an embodiment of the present application provides an electric heating temperature control device, which uses an AC power supply and an external heating wire. The heating wire includes a temperature-sensing conductor, an insulating isolation layer, and a heating conductor. The temperature-sensing conductor is at least used to sense the temperature of the heating conductor. The insulating isolation layer is used to insulate and isolate the conductors, and the insulating isolation layer will produce a change in resistance value or cause a short circuit between the conductors when the local or overall temperature changes. The heating conductor is at least used for heating. The electric heating temperature control device includes: a temperature detection circuit, a heating switch circuit, and a temperature parameter setting circuit; the temperature detection circuit includes a temperature-sensing voltage-dividing sampling unit, an AC voltage-dividing sampling unit, and a differential signal processing unit; the first end of the temperature-sensing voltage-dividing sampling unit is connected to the second end of the temperature-sensing conductor, the first end of the temperature-sensing conductor is connected to the live wire of the AC power supply, the second end of the temperature-sensing voltage-dividing sampling unit is grounded, the output end of the temperature-sensing voltage-dividing sampling unit is connected to the differential signal processing unit, and the temperature-sensing voltage-dividing sampling unit is used to convert the signal flowing through the temperature-sensing conductor into a temperature voltage The signal is output to the differential signal processing unit; the first end of the AC voltage dividing sampling unit is connected to the live wire of the AC power supply, the second end of the AC voltage dividing sampling unit is grounded, and the output end of the AC voltage dividing sampling unit is connected to the differential signal processing unit, and the AC voltage dividing sampling unit is used to convert the input signal of the AC power supply into a reference voltage signal and output it to the differential signal processing unit; the differential signal processing unit is used to perform differential comparison and identification processing on the temperature voltage signal and the reference voltage signal to suppress the influence of the AC power supply voltage change on the accuracy of temperature detection, judge the temperature of the temperature sensing conductor and output a stop heating signal or a heating signal; the heating switch circuit is connected to the temperature detection circuit and the heating conductor, and is used to disconnect the power supply circuit of the heating conductor when receiving the stop heating signal, and to connect the power supply circuit of the heating conductor when receiving the heating signal, so as to control the heating conductor to heat or stop heating; the temperature parameter setting circuit is connected to the temperature detection circuit, and is used to set the temperature parameter.

[0007] In one embodiment, the electric heating temperature control device also includes: a safety protection circuit, which is connected to the heating switch circuit and the heating conductor. The safety protection circuit utilizes the characteristic that the insulation isolation layer will produce a change in resistance value or cause a short circuit between conductors when the local or overall temperature changes. By detecting the leakage current of the insulation isolation layer, the local or overall temperature of the heating conductor is detected. When the temperature is greater than a preset safety value, an abnormal signal is output to control the heating switch circuit to disconnect the power supply circuit of the heating conductor.

[0008] In one embodiment, the heating switch circuit includes a first switch unit and a second switch unit; the first end of the first switch unit is connected to the live wire of the AC power supply or the second end of the temperature-sensing conductor, the second end of the first switch unit is connected to the first end of the heating conductor, the first end of the second switch unit is connected to the second end of the heating conductor, and the second end of the second switch unit is grounded or equivalently grounded; by controlling the conduction of the first switch unit and the second switch unit, the power supply circuit of the heating conductor is connected; by controlling the disconnection of the first switch unit or the second switch unit, the power supply circuit of the heating conductor is disconnected; by controlling the disconnection of the first switch unit and the second switch unit, the heating current at both ends of the heating conductor is disconnected, so that the safety protection circuit can more accurately detect the leakage current of the insulating isolation layer and the temperature detection circuit can more accurately detect the temperature of the temperature-sensing conductor.

[0009] In one embodiment, the safety protection circuit is further configured to output an abnormality signal when the temperature detection circuit operates abnormally or the heating switch circuit operates abnormally, and control the heating switch circuit to disconnect the power supply circuit of the heating conductor.

[0010] In one embodiment, the heating switch circuit includes a first switch unit and a second switch unit; the temperature-sensitive voltage-dividing sampling unit includes a first resistor and a second resistor, the first end of the first resistor is connected to the output end of the temperature-sensitive conductor using a diode or directly, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is grounded, and the series node of the first resistor and the second resistor is connected to the differential signal processing unit as the output end of the temperature-sensitive voltage-dividing sampling unit; or, the temperature-sensitive voltage-dividing sampling unit includes a second resistor, the first end of the heating conductor is connected to the output end of the temperature-sensitive conductor through the first switch unit, and the second end of the heating conductor is connected to the first end of the second resistor through the second switch unit. The second end of the second resistor is grounded, and the first end of the second resistor is also connected to the differential signal processing unit as the output end of the temperature-sensitive voltage-dividing sampling unit; the AC voltage-dividing sampling unit includes a third resistor and a fourth resistor, the first end of the third resistor is connected to the live wire of the AC power supply using a diode or directly, the second end of the third resistor is connected to the first end of the fourth resistor, the second end of the fourth resistor is grounded, and the series node of the third resistor and the fourth resistor is connected to the differential signal processing unit as the output end of the AC voltage-dividing sampling unit; the diodes used in the temperature-sensitive voltage-dividing sampling unit and the AC voltage-dividing sampling unit are both used to simultaneously intercept the voltage of the positive half-cycle or the negative half-cycle of the AC power supply for voltage-dividing sampling.

[0011] In one embodiment, the differential signal processing unit includes a first voltage comparator and a second voltage comparator, the first input end of the first voltage comparator is connected to the output end of the temperature-sensitive voltage-dividing sampling unit, the second input end of the first voltage comparator is connected to the output end of the AC voltage-dividing sampling unit, the output end of the first voltage comparator is connected to the second input end of the second voltage comparator, the first input end of the second voltage comparator is connected to a voltage source, and the output end of the second voltage comparator is connected to the heating switch circuit; or the differential signal processing unit includes a third voltage comparator and a single-chip microcomputer , the first input end of the third voltage comparator is connected to the output end of the temperature-sensing voltage-dividing sampling unit, the second input end of the third voltage comparator is connected to the output end of the AC voltage-dividing sampling unit, the output end of the third voltage comparator is connected to the single-chip microcomputer, and the single-chip microcomputer is also connected to the heating switch circuit; or, the differential signal processing unit includes a single-chip microcomputer, the output end of the temperature-sensing voltage-dividing sampling unit is connected to the first analog-to-digital conversion port of the single-chip microcomputer, the output end of the AC voltage-dividing sampling unit is connected to the second analog-to-digital conversion port of the single-chip microcomputer, and the single-chip microcomputer is also connected to the heating switch circuit.

[0012] In one embodiment, the safety protection circuit includes a safety signal sampling unit and a safety signal processing unit; the first end of the safety signal sampling unit is connected to the second end of the heating conductor, and the second end of the safety signal sampling unit is grounded or connected to the voltage output end of the power supply circuit, and the safety signal sampling unit is used to convert the current signal flowing through its unit into a safety voltage signal and output it to the safety signal processing unit; the safety signal processing unit is connected to the heating switch circuit, and the safety signal processing unit performs abnormality analysis and judgment based on the received abnormality judgment timing and the safety voltage signal. When an abnormality exists, the safety signal processing unit outputs an abnormality signal to the heating switch circuit; the heating switch circuit is also connected to the safety signal processing unit, and the heating switch circuit is also used to disconnect the power supply circuit of the heating conductor when receiving the abnormal signal.

[0013] In one embodiment, the electric heating temperature control device also includes: a timed power-off temperature measurement circuit, which is used to directly or indirectly control the heating switch circuit to forcibly disconnect the heating for a certain period of time after each continuous heating period. The electric heating temperature control device uses the heating switch circuit to perform temperature detection when the heating is disconnected to avoid the AC power supply from leaking to the temperature sensing conductor through the heating conductor and the insulating isolation layer, thereby affecting the accuracy of temperature detection.

[0014] In one embodiment, the temperature detection circuit performs temperature detection during the positive half cycle of the AC power supply, and the safety protection circuit performs abnormality detection during the negative half cycle of the AC power supply; or the temperature detection circuit performs temperature detection during the negative half cycle of the AC power supply, and the safety protection circuit performs abnormality detection during the positive half cycle of the AC power supply; this is used to avoid conflict between the temperature detection circuit and the safety protection circuit during operation.

[0015] A second aspect of the present application provides an electric heating device, which includes the electric heating temperature control device in any of the above embodiments.

[0016] Compared with the prior art, the embodiments of the present application have the following beneficial effects: through the voltage differential comparison and identification processing of the temperature detection circuit, the AC power supply voltage change and the error change of the working voltage of the temperature-sensing conductor can be suppressed, the impact on the detection accuracy of the temperature-sensing conductor is reduced, the accuracy of the temperature-sensing conductor in sensing temperature changes is improved, high-precision temperature detection of the temperature detection circuit is achieved, accurate temperature detection is achieved, and the problem of inaccurate temperature detection of the electric heating temperature control device is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the principle of an electric heating temperature control device provided in one embodiment of the present application;

[0018] Figure 2 A schematic diagram showing the principle of an electric heating temperature control device provided in another embodiment of the present application;

[0019] Figure 3 A circuit diagram of an electric heating temperature control device provided in one embodiment of the present application;

[0020] Figure 4 A circuit diagram of an electric heating temperature control device provided in another embodiment of the present application;

[0021] Figure 5 A circuit diagram of an electric heating temperature control device provided in another embodiment of the present application;

[0022] Figure 6 This is a circuit schematic diagram of an electric heating temperature control device provided in another embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0024] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0025] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0027] like Figure 1 As shown, the first aspect of the embodiment of the present application provides an electric heating temperature control device 100, which uses an alternating current (AC) power supply and an external heating wire 200. The heating wire 200 includes a temperature-sensing conductor 210, an insulating isolation layer 220, and a heating conductor 230. The temperature-sensing conductor 210 is at least used to sense the temperature of the heating conductor 230. The temperature-sensing conductor 210 can use a conductor with a positive temperature coefficient (PTC) characteristic. The insulating isolation layer 220 can also be used for insulation isolation between the temperature-sensing conductor 210 and the heating conductor 230. When the temperature of the local or overall part of the insulation isolation layer 220 changes, the resistance value will change or a short circuit will be generated between the conductors. The heating conductor 230 is at least used for heating. Please refer to Figure 1 The electric heating temperature control device 100 includes a temperature detection circuit 110, a heating switch circuit 120 and a temperature parameter setting circuit 160.

[0028] The temperature detection circuit 110 includes an AC voltage division sampling unit 111 , a temperature-sensing voltage division sampling unit 112 , and a differential signal processing unit 113 .

[0029] The first end of the temperature-sensing voltage-dividing sampling unit 112 is connected to the second end of the temperature-sensing conductor 210, the first end of the temperature-sensing conductor 210 is connected to the live wire L of the AC power supply, the second end of the temperature-sensing voltage-dividing sampling unit 112 is grounded, and the output end of the temperature-sensing voltage-dividing sampling unit 112 is connected to the differential signal processing unit 113. The temperature-sensing voltage-dividing sampling unit 112 is used to convert the signal flowing through the temperature-sensing conductor 210 into a temperature voltage signal and output it to the differential signal processing unit 113.

[0030] A first end of the AC voltage dividing sampling unit 111 is connected to the live wire L of the AC power supply, a second end of the AC voltage dividing sampling unit 111 is grounded, and an output end of the AC voltage dividing sampling unit 111 is connected to the differential signal processing unit 113. The AC voltage dividing sampling unit 111 is used to convert the input signal of the AC power supply into a reference voltage signal and output it to the differential signal processing unit 113.

[0031] The differential signal processing unit 113 is used to perform differential comparison and identification processing on the temperature voltage signal and the reference voltage signal to suppress the influence of the AC power supply voltage change on the accuracy of temperature detection, determine the temperature of the temperature sensing conductor 210 and output a stop heating signal or a heating signal.

[0032] The heating switch circuit 120 is connected to the temperature detection circuit 110 and the heating conductor 230. The heating switch circuit 120 is used to disconnect the power supply circuit of the heating conductor 230 when receiving a stop heating signal, and to connect the power supply circuit of the heating conductor 230 when receiving a heating signal.

[0033] The temperature parameter setting circuit 160 is connected to the differential signal processing unit 113 and is used to set the temperature parameter. Specifically, the temperature parameter setting circuit 160 adjusts the reference voltage signal output by the AC voltage-dividing sampling unit 111 to set the temperature parameter of the temperature-sensing conductor 210. The temperature parameter is adjusted by changing the potential of the reference voltage signal. In some embodiments, the temperature parameter setting circuit 160 can be implemented using an adjustable resistor. In some embodiments, the temperature parameter setting circuit 160 can be implemented using a keypad in combination with a resistor. In other embodiments, the temperature parameter setting circuit 160 can be implemented using wireless methods such as infrared and Bluetooth.

[0034] In a first aspect, an embodiment of the present application provides an electric heating temperature control device 100, which performs differential comparison and identification processing on a temperature voltage signal and a reference voltage signal through an AC voltage-dividing sampling unit 111, a temperature-sensing voltage-dividing sampling unit 112, and a differential signal processing unit 113 of a temperature detection circuit 110. This can suppress the change in AC power supply voltage and the error change in the working voltage of a temperature-sensing conductor 210, reduce the impact on the detection accuracy of the temperature-sensing conductor 210, improve the accuracy of the temperature-sensing conductor 210 in sensing temperature changes, achieve high-precision temperature detection by the temperature detection circuit 110, and solve the problem of inaccurate temperature detection in traditional electric heating devices.

[0035] See also Figure 2 In one embodiment, the electric heating temperature control device 100 further includes a timed power-off temperature measurement circuit 130, which is connected to the temperature detection circuit 110 and is used to directly or indirectly control the heating switch circuit 120 to forcibly disconnect the heating for a certain period of time after each continuous heating period. The electric heating temperature control device 100 uses the heating switch circuit 120 to perform temperature detection when the heating is disconnected, thereby preventing the AC power from leaking to the temperature sensing conductor 210 through the heating conductor 230 and the insulating isolation layer 220, thereby affecting the accuracy of temperature detection.

[0036] See also Figure 2 In one embodiment, the electric heating temperature control device 100 further includes a safety protection circuit 140, which is connected to the heating switch circuit 120 and the heating conductor 230. The safety protection circuit 140 utilizes the characteristic that the insulation isolation layer 220 will produce a resistance value change or cause a short circuit between conductors when the local or overall temperature changes. By detecting the leakage current of the insulation isolation layer 220, the local or overall temperature of the heating conductor 230 is detected. When the temperature is greater than a preset safety value, an abnormal signal is output, and the safety protection circuit 140 controls the heating switch circuit 120 to disconnect the power supply circuit of the heating conductor 230.

[0037] See also Figure 2 Specifically, in one embodiment, the heating switch circuit 120 includes a first switch unit 121 and a second switch unit 122. A first end of the first switch unit 121 is connected to the live wire L of the AC power source or the second end of the temperature-sensing conductor 210, a second end of the first switch unit 121 is connected to the first end of the heating conductor 230, i.e., the current input end of the heating conductor 230, a first end of the second switch unit 122 is connected to the second end of the heating conductor 230, i.e., the current output end of the heating conductor 230, and a second end of the second switch unit 122 is grounded or equivalently grounded.

[0038] By controlling the conduction of the first switch unit 121 and the second switch unit 122, the power supply circuit of the heating conductor 230 is connected. By controlling the disconnection of the first switch unit 121 or the second switch unit 122, the power supply circuit of the heating conductor 230 is disconnected. By controlling the disconnection of the first switch unit 121 and the second switch unit 122, the heating current at both ends of the heating conductor 230 is disconnected, allowing the safety protection circuit 140 to more accurately detect the leakage current of the insulating isolation layer 220, and allowing the temperature detection circuit 110 to more accurately detect the temperature of the temperature-sensing conductor 210.

[0039] See also Figure 2In one embodiment, the safety protection circuit 140 is further configured to output an abnormality signal to the heating switch control circuit 12 when the temperature detection circuit 110 or the heating switch circuit 120 is abnormal, so as to control the heating switch circuit 120 to disconnect the power supply circuit of the heating conductor 230. Figure 2 For example, when the temperature detection circuit 110 and the heating switch circuit 120 work abnormally and the first switch unit 121 or the second switch unit 122 is continuously turned on, an abnormal signal is output to control the heating switch circuit 120 to disconnect the power supply circuit of the heating conductor 230.

[0040] See also Figure 2 Furthermore, in one embodiment, the electric heating temperature control device 100 also includes a power supply circuit 150, which is connected to an AC power supply. The power supply circuit 150 is used to convert the voltage of the AC power supply into a DC regulated voltage to provide a DC voltage source required for the operation of the temperature detection circuit 110 and the safety protection circuit 140.

[0041] Further, in one embodiment, see Figure 3 The temperature-sensing voltage-dividing sampling unit 112 includes a first resistor R17 and a second resistor R18. The first end of the first resistor R17 is connected to the output end of the temperature-sensing conductor 210 via a diode D8. That is, the first end of the first resistor R17 is connected to the cathode of the diode D8, and the anode of the diode D8 is connected to the output end of the temperature-sensing conductor 210. Alternatively, the first end of the first resistor R17 is directly connected to the output end of the temperature-sensing conductor 210, the second end of the first resistor R17 is connected to the first end of the second resistor R18, and the second end of the second resistor R18 is grounded. The series connection node of the first resistor R17 and the second resistor R18 serves as the output end of the temperature-sensing voltage-dividing sampling unit 112 and is connected to the differential signal processing unit 113.

[0042] See also Figure 3 The AC voltage division sampling unit 111 includes a third resistor R15 and a fourth resistor R16. The first end of the third resistor R15 is connected to the live wire of the AC power supply via a diode D7. That is, the first end of the third resistor R15 is connected to the cathode of the diode D7, and the anode of the diode D7 is connected to the live wire of the AC power supply. Alternatively, the first end of the third resistor R15 is directly connected to the live wire of the AC power supply, the second end of the third resistor R15 is connected to the first end of the fourth resistor R16, and the second end of the fourth resistor R16 is grounded. The series connection node of the third resistor R15 and the fourth resistor R16 serves as the output end of the AC voltage division sampling unit 111 and is connected to the differential signal processing unit 113.

[0043] It can be understood that the diode D7 and the diode D8 used in the temperature-sensing voltage-dividing sampling unit 112 and the AC voltage-dividing sampling unit 111 are both used to simultaneously intercept the voltage of the positive half cycle or the negative half cycle of the AC power supply for voltage-dividing sampling.

[0044] Alternatively, see Figure 3 The differential signal processing unit 113 includes a first voltage comparator U3 and a second voltage comparator U4. The first input terminal, i.e., the non-inverting input terminal, of the first voltage comparator U3 is connected to the output terminal of the temperature-sensing voltage-dividing sampling unit 112. The second input terminal, i.e., the inverting input terminal, of the first voltage comparator U3 is connected to the output terminal of the AC voltage-dividing sampling unit 111. The output terminal of the first voltage comparator U3 is connected to the second input terminal of the second voltage comparator U4 via a diode D9 and a resistor R20. The first input terminal of the second voltage comparator U4 is connected to the power supply VDD via a resistor R22. The output terminal of the second voltage comparator U4 is connected to the heating switch circuit 120.

[0045] Alternatively, see Figure 4 The differential signal processing unit 113 includes a third voltage comparator U7 and a single-chip microcomputer U6. The first input end of the third voltage comparator U7 is connected to the output end of the temperature-sensing voltage-dividing sampling unit 112, the second input end of the third voltage comparator U7 is connected to the output end of the AC voltage-dividing sampling unit 111, and the output end of the third voltage comparator U7 is connected to the single-chip microcomputer U6. The single-chip microcomputer U6 is also connected to the heating switch circuit 120.

[0046] Alternatively, see Figure 5 The differential signal processing unit 113 includes a single-chip microcomputer U9. The output end of the temperature-sensing voltage-dividing sampling unit 112 is connected to the first analog-to-digital conversion port of the single-chip microcomputer U9, that is, the 16th pin of the single-chip microcomputer U9. The output end of the AC voltage-dividing sampling unit 111 is connected to the second analog-to-digital conversion port of the single-chip microcomputer U9, that is, the 15th pin of the single-chip microcomputer U9. The single-chip microcomputer U9 is also connected to the heating switch circuit 120.

[0047] See also Figure 2 Specifically, in one embodiment, the safety protection circuit 140 includes a safety signal sampling unit 141 and a safety signal processing unit 142. A first end of the safety signal sampling unit 141 is connected to the second end of the heating conductor 230, and a second end of the safety signal sampling unit 141 is grounded or connected to the voltage output terminal of the power supply circuit 150. The safety signal sampling unit 141 is configured to convert the current signal flowing through the unit into a safety voltage signal and output it to the safety signal processing unit 142.

[0048] The safety signal processing unit 142 is connected to the heating switch circuit 120. The safety signal processing unit 142 performs abnormal analysis and judgment based on the received abnormal judgment timing and safety voltage signal. When an abnormality exists, the safety signal processing unit 142 outputs an abnormal signal to the heating switch circuit 120. In one embodiment, refer to Figure 2 The abnormality judgment timing is provided by the timed power-off temperature measurement circuit 130, for example.

[0049] The heating switch circuit 120 is also connected to the safety signal processing unit 142 . The heating switch circuit 120 is also used to disconnect the power supply circuit of the heating conductor 230 when receiving an abnormal signal.

[0050] See also Figure 2 Specifically, in one embodiment, the temperature detection circuit 110 performs temperature detection during the positive half cycle of the AC power supply, and the safety protection circuit 140 performs abnormality detection during the negative half cycle of the AC power supply; or the temperature detection circuit 110 performs temperature detection during the negative half cycle of the AC power supply, and the safety protection circuit 140 performs abnormality detection during the positive half cycle of the AC power supply; this is used to avoid conflict between the temperature detection circuit 110 and the safety protection circuit 140 during operation, and further improve the stability of the electric heating temperature control device 100 of the present application during operation.

[0051] It can be understood that the neutral line N of the AC power supply in this embodiment is grounded, so the ground terminal mentioned in this embodiment can be based on the potential of the neutral line N of the AC power supply as a reference ground.

[0052] like Figure 1 and 2 As shown in the figure, they are the circuit implementation principle block diagrams of the embodiments of the present application, and the specific implementation details are as follows Figure 3 As shown, Figure 3 Shown is a circuit diagram of an implementation of an embodiment of the present application.

[0053] See also Figure 3 The AC voltage dividing sampling unit 111 includes a second diode D7, a third resistor R15, and a fourth resistor R16. The anode of the second diode D7 is connected to the live wire L of the AC power supply, the cathode of the second diode D7 is connected to one end of the third resistor R15, the other end of R15 is connected to one end of the fourth resistor R16, and the other end of the fourth resistor R16 is grounded. The series connection node between the third resistor R15 and the fourth resistor R16 serves as the output end of the AC voltage dividing sampling unit 111 and is connected to the differential signal processing unit 113.

[0054] See also Figure 3The temperature-sensing voltage-dividing sampling unit 112 includes a first diode D8, a first resistor R17, and a second resistor R18. The anode of the first diode D8 is connected to the current output end of the temperature-sensing conductor 210, the cathode of the first diode D8 is connected to the first end of the first resistor R17, the second end of R17 is connected to the first end of the second resistor R18, and the second end of the second resistor R18 is grounded. The series connection node of the first resistor R17 and the second resistor R18 serves as the output end of the temperature-sensing voltage-dividing sampling unit 112 and is connected to the differential signal processing unit 113.

[0055] See also Figure 3 The differential signal processing unit 113 includes a first voltage comparator U3 and a second voltage comparator U4. The first input terminal of the first voltage comparator U3 is connected to the output terminal of the temperature-sensing voltage-dividing sampling unit 112, and the second input terminal of the first voltage comparator U3 is connected to the output terminal of the AC voltage-dividing sampling unit 111. The output terminal of the first voltage comparator U3 is connected to the second input terminal of the second voltage comparator U4 through a diode D9 and a resistor R20. The first input terminal of the second voltage comparator U4 is connected to the power supply VDD through a resistor R22. One end of the resistor R23 is grounded, and the other end of the resistor R23 is connected to the first input terminal of the second voltage comparator U4. The resistor R24 ​​is connected between the first input terminal and the output terminal of the second voltage comparator U4. The output terminal of the second voltage comparator U4 is connected to the heating switch circuit 120. The voltage comparison processing unit 1232 in this embodiment is implemented by the first voltage comparator U3 and the second voltage comparator U4.

[0056] See also Figure 3 The temperature parameter setting circuit 160 is connected to the AC voltage dividing sampling unit 111 and is used to adjust the reference voltage signal output by the AC voltage dividing sampling unit 111 to set the temperature parameter of the temperature sensing conductor 210. The differential signal processing unit 113 is used to perform differential comparison and identification processing on the temperature voltage signal and the adjusted reference voltage signal.

[0057] See also Figure 3 The temperature parameter setting circuit 160 includes an adjustable resistor VR1, a first end of the adjustable resistor VR1 is connected to the output end of the AC voltage dividing sampling unit 111, and a second end of the adjustable resistor VR1 is grounded. The adjustable resistor VR1 is used to adjust the reference voltage signal output by the AC voltage dividing sampling unit 111 to set the temperature parameter of the temperature sensing conductor 210.

[0058] The first input of the first voltage comparator U3 is connected to the output of the temperature-sensing voltage-dividing sampling unit 112. The second input of the first voltage comparator U3 is connected to the output of the AC voltage-dividing sampling unit 111. The output of the first voltage comparator U3 is connected to the second input of the second voltage comparator U4 via a diode D9 and a resistor R20. The first input of the second voltage comparator U4 is connected to the power supply VDD via a resistor R22. One end of the resistor R23 is grounded, and the other end of the resistor R23 is connected to the first input of the second voltage comparator U4. The resistor R24 ​​is connected between the first input and output of the second voltage comparator U4. The output of the second voltage comparator U4 is connected to the heating switch circuit 120. The voltage comparison processing unit 1232 in this embodiment is implemented by the first voltage comparator U3 and the second voltage comparator U4.

[0059] Among them, the voltage division change of the resistor R18 caused by the temperature change of the heating conductor 230 is a differential mode signal, which will be separated and compared, and the comparison result is output from the output end of the voltage comparator U3; when the voltage input to the first input end of the voltage comparator U3 is lower than the voltage input to the second input end of the voltage comparator U3, it means that the temperature is higher than the temperature set by the user, and the voltage comparator U3 outputs a stop heating signal; otherwise, it means that the temperature is lower than the temperature set by the user, and the output end of the voltage comparator U3 outputs a heating signal.

[0060] See also Figure 3 The first switch unit 121 includes a first bidirectional thyristor TR2 and a first optocoupler OC2, and the second switch unit 122 includes a second bidirectional thyristor TR1 and a second optocoupler OC1. The first main electrode of the first bidirectional thyristor TR2 is connected to the live wire L of the AC power supply, the second main electrode of the first bidirectional thyristor TR2 is connected to the input end of the heating conductor 230, the control electrode of the first bidirectional thyristor TR2 is connected to the first output end of the second optocoupler OC1, the second output end of the first optocoupler OC2 is connected to the first main electrode of the first bidirectional thyristor TR2 via a resistor R3, and the first input end of the first optocoupler OC2 is connected to the safety protection circuit 140 via a resistor R4. The first main electrode of the second bidirectional thyristor TR1 is connected to the output end of the heating conductor 230, the second main electrode of the second bidirectional thyristor TR1 is grounded, the control electrode of the second bidirectional thyristor TR1 is connected to the first output end of the second optocoupler OC1, the second output end of the second optocoupler OC1 is connected to the first main electrode of the first bidirectional thyristor TR2 through the resistor R26, the first input end of the second optocoupler OC1 is connected to the temperature detection circuit 110 through the resistor R25, and the second input end of the first optocoupler OC2 is connected to the second input end of the second optocoupler OC1.

[0061] See also Figure 3The timed power-off temperature measurement circuit 130 is composed of a voltage comparator U5 and its peripheral components, resistors R28, R29, R30, R31, R32, R33, capacitor C5, diode D10, and diode D11. The anode of diode D10 is the signal output terminal of the timed power-off temperature measurement circuit 130 and is connected to the differential signal processing unit 113. The timed power-off temperature measurement circuit 130 can output a low-level voltage for a period of time at regular intervals, forcing the temperature detection circuit 110 to output a stop heating signal, and providing an abnormality judgment timing sequence to the safety signal processing unit 142 for abnormality judgment. At the same time, the temperature detection circuit 110 uses the heating switch circuit 120 to turn off the heating to perform temperature detection, thereby preventing the AC power from leaking to the insulating isolation layer 220 or the temperature-sensing conductor 210 through the heating conductor 230, thereby affecting the accuracy of temperature detection.

[0062] See also Figure 3 The safety signal sampling unit 141 includes a diode D5 and a resistor R27. The cathode of the diode D5 is connected to the output end of the heating conductor 230, the anode of the diode D5 is connected to one end of the resistor R27, and the other end of the resistor R27 is grounded. The series node of the diode D5 and the resistor R27 serves as the output end of the safety signal sampling unit 141 and is connected to the safety signal processing unit 142. The function of the diode D5 is to allow the safety signal sampling unit 141 to intercept the negative half cycle of the AC power supply to sample abnormal voltage.

[0063] Specifically, see Figure 3The safety signal processing unit 142 recognizes and processes the safety voltage signal output by the safety signal sampling unit 141 through the voltage comparator U2 and the voltage comparator U1. The safety signal processing unit 142 includes an abnormal signal processor composed of the voltage comparator U2 and its peripheral components, a diode D6, a diode D4, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C6, and a capacitor C7; the resistor R13 and the resistor R14 are connected in series, and the connection point is connected to the second input end of the voltage comparator U2. The other end of the resistor R13 is connected to the voltage source VDD provided by the power supply circuit 150. The other end of the resistor R14 is connected to the signal output end of the safety signal sampling unit 141 as the signal input end of the safety signal processing unit 142. The capacitor C7 is used to filter Wave, diode D4 is used for overvoltage protection; resistor R10, resistor R11, resistor R12, diode D6 and capacitor C6 form the same structure as the second input terminal of voltage comparator U2, providing abnormal reference voltage to the first input terminal of voltage comparator U2, and the same structure can prevent the change of AC power supply voltage from affecting the accuracy of abnormal detection; when an abnormal situation occurs, the safety signal sampling unit 141 outputs a safety voltage signal to the second input terminal of voltage comparator U2, causing voltage comparator U2 to output a high-level voltage, and the voltage comparator U1 and its peripheral components resistor R5, resistor R6, resistor R7, resistor R8 and capacitor C3 form a time-delay breaker, which can output an abnormal signal for a period of time after the voltage comparator U2 outputs a high-level voltage to stop heating, thereby achieving safety protection.

[0064] See also Figure 3 In one embodiment, the power supply circuit 150 is composed of a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, a diode D1, a diode D2, and a voltage regulator Z1. The power supply circuit 150 is used to provide the required working voltage source VDD for each unit circuit. The specific connection relationship of the power supply circuit 150 is not the focus of this application and will not be repeated here.

[0065] like Figure 4 Shown is another circuit diagram of an embodiment of the present application.

[0066] See also Figure 4The temperature parameter setting circuit 160 includes a plurality of buttons, and the differential signal processing unit 113 includes a single-chip microcomputer U6 and a third voltage comparator U7. The plurality of buttons include a button SW1, a button SW2, and a button SW3. The first ends of the buttons SW1, SW2, and SW3 are commonly grounded, and the second ends of the buttons SW1, SW2, and SW3 are commonly connected to the 15th pin of the single-chip microcomputer U6. The output end of the AC voltage dividing sampling unit 111 is connected to the 16th pin of the single-chip microcomputer U6 through the third voltage comparator U7, that is, the output end of the AC voltage dividing sampling unit 111 is connected to the second input end of the third voltage comparator U7. The output end of the AC voltage dividing sampling unit 111 is connected to the resistor R34, the resistor R35, the resistor R36, and the resistor R37 through the diode D12. One end of the resistor R34, the resistor R35, the resistor R36 and the resistor R37 are connected to the 14th, 13th, 12th and 11th pins of the single-chip computer U6 respectively, and the temperature parameter is input through the button SW1, the button SW2 and the button SW3. Then, the temperature parameter potential corresponding to the setting is output through the 14th, 13th, 12th and 11th pins of the single-chip computer and the resistor R34, the resistor R35, the resistor R36, the resistor R37 and the diode D12, the voltage divider of the fourth resistor R16 is changed, and the reference voltage signal output by the AC voltage divider sampling unit 111 is adjusted to set the temperature parameter of the temperature-sensing conductor 210.

[0067] The single chip microcomputer U6 is also connected to the output end of the temperature sensing voltage sampling unit 112 and the heating switch circuit 120. The single chip microcomputer U6 is used to perform differential comparison and identification processing on the temperature voltage signal and the adjusted reference voltage signal. Figure 4 , also includes a display DS1, the display DS1 is, for example, a 1602 display screen, and the display DS1 can be used to display the temperature parameter setting content and the working status of the electric heating temperature control device 100.

[0068] See also Figure 4 The first switch unit 121 includes a first diode D13 and a temperature fuse F1, and the second switch unit 122 includes a first thyristor T3, a second diode D14, a resistor R42, a resistor R43 and a first capacitor C8.

[0069] The anode of the first diode D13 is connected to the output end of the temperature-sensing conductor 210, and the cathode of the first diode D13 is connected to the input end of the heating conductor 230. The first diode D13 is configured to conduct the positive half-cycle of the AC power supply and disconnect the negative half-cycle of the AC power supply. The first end of the thermal fuse F1 is connected to the neutral line N of the AC power supply, and the second end of the thermal fuse F1 is connected to ground. When the thermal fuse F1 blows, it is configured to disconnect and stop heating the heating conductor 230. In actual circuit design, the thermal fuse F1 can be placed next to the resistor R27 of the safety signal sampling unit 141, that is, the thermal fuse F1 is located close to the resistor R27. When the thermal fuse F1 blows, the heating can be disconnected.

[0070] The anode of the first thyristor T3 is connected to the output end of the heating conductor 230, the cathode of the first thyristor T3 is grounded, the resistor R42, the first capacitor C8 and the second diode D14 are connected in series between the temperature detection circuit 110 and the ground end, the anode of the second diode D14 is grounded, the control electrode of the first thyristor T3 is connected to the cathode of the second diode D14, and the resistor R43 is connected in parallel with the second diode D14. Figure 4 The resistor R42, the first capacitor C8 and the second diode D14 are connected in series between the 9th pin of the microcontroller U6 and the ground terminal. The microcontroller U6 realizes heating and heating off by controlling the conduction or disconnection of the first one-way thyristor T3.

[0071] See also Figure 4 The timed power-off temperature measurement circuit 130 can be set in the single-chip microcomputer U6.

[0072] See also Figure 5 Furthermore, the safety signal processing unit 142 includes a voltage comparator U2 and its peripheral components, a diode D16, a diode D15, a resistor R45, a resistor R46, a resistor R47, a resistor R48, and a resistor R49. Resistors R48 and R49 are connected in series, and the series node of resistors R48 and R49 is connected to the second input terminal of the voltage comparator U2. The other end of resistor R48 is connected to the operating voltage source VDD provided by the power supply circuit 150. The other end of resistor R49 is connected to the output terminal of the safety signal sampling unit 141 as the input terminal of the safety signal processing unit 142. Diode D15 is used for overvoltage protection. Resistors R46, R46, R47, and diode D16 form the same structure as the second input terminal of the voltage comparator U2, providing an abnormality reference voltage to the first input terminal of the voltage comparator U2. This same structure can prevent changes in the AC power supply voltage from affecting the accuracy of abnormality detection.

[0073] When an abnormality occurs, such as a failure of the first switch unit 121, a prolonged conduction abnormality, an abnormal overtemperature of the heating conductor 230 detected by the insulating layer 220, or a short circuit abnormality caused by insulation damage of the insulating layer 220, the safety signal sampling unit 141 outputs the sampled safety voltage signal to the second input terminal of the voltage comparator U2, causing the voltage comparator U2 to output a high-level voltage. The safety signal processing unit 142 also includes a single-chip microcomputer U6 and a processing program within the single-chip microcomputer U6. The safety signal processing unit 142 receives the voltage output by the voltage comparator U2 through pin 10 of the single-chip microcomputer U6.

[0074] Among them, the safety signal processing unit 142 identifies the abnormality in the following way: when the voltage comparator U2 outputs a high-level voltage, if it can output a low-level voltage after the timed power-off temperature measurement circuit 130 is forced to disconnect the heating, it means that the high-level voltage output by the voltage comparator U2 is caused by the heating switch circuit 120 being turned on for heating, which is in line with the abnormality judgment timing; when the voltage comparator U2 outputs a high-level voltage, if it still outputs a high-level voltage after the timed power-off temperature measurement circuit 130 is forced to disconnect the heating, it means that the high-level voltage output by the voltage comparator U2 is caused by an abnormality in the circuit, which is not in line with the abnormality judgment timing. The timing is often judged, and the 9th pin of the single-chip microcomputer U6 outputs a stop heating signal to control the second switch unit 122 to disconnect the heating to achieve safety protection; when the second switch unit 122 fails and the long conduction is abnormal, the temperature of the heating conductor 230 will rise. When the insulation isolation layer 220 causes the resistance value between the temperature-sensing conductor 210 and the heating conductor 230 to be small or short-circuited due to the high temperature, the resistor R27 will heat up due to the excessive current passing through it. Since the temperature fuse F1 is arranged in close proximity to the resistor R27, the temperature fuse F1 will melt due to the heat of the resistor R27, thereby disconnecting the heating to achieve safety protection.

[0075] See also Figure 4 Furthermore, the safety signal processing unit 142 also includes a resistor R44, a voltage-stabilizing diode Z2, a single-chip microcomputer U6 and its internal zero-crossing detection program to form an AC power zero-crossing detection unit, which is used to detect the zero-crossing point of the AC power supply, so that the single-chip microcomputer U6 can control the on and off time of the second switch unit 122, and the single-chip microcomputer U6 can grasp the time point of reading the temperature voltage value during temperature detection or the time point of reading the abnormal voltage value during abnormality detection.

[0076] See also Figure 4Furthermore, microcontroller U6 includes a timed power-off temperature measurement program. This program, via pin 9 of microcontroller U6, controls the heating switch circuit 120 to forcibly disconnect heating for a specified period of time after a certain period of continuous heating. This program provides the safety signal processing unit 142 with an abnormality detection timing sequence for use in abnormality detection. Simultaneously, the temperature detection circuit 110 performs temperature detection when the heating switch circuit 120 is disconnected from heating, preventing AC power from leaking through the heating conductor 230 to the insulation isolation layer 220 or the temperature-sensing conductor 210, potentially affecting temperature detection accuracy.

[0077] See also Figure 4 The temperature detection circuit 110 uses a single-chip microcomputer U6 and a third voltage comparator U7 to perform voltage differential comparison and identification processing on the temperature voltage signal output from the voltage divider output end of the temperature-sensing voltage divider sampling unit 112 and the reference voltage signal output from the output end of the AC voltage divider sampling unit 111, thereby suppressing the influence of the AC power supply voltage change and the working voltage error change on the temperature detection accuracy. In addition, the temperature detection circuit 110 performs temperature detection when the heating switch circuit 120 is disconnected, thereby avoiding the AC power supply from leaking to the temperature-sensing conductor 210 and affecting the accuracy of temperature detection. By adopting the above-mentioned technical means, the temperature changes sensed by the temperature-sensing conductor 210 can be accurately extracted, and high-precision temperature detection and temperature control can be achieved. In addition, the safety protection circuit 140 adopts the timed power-off temperature measurement circuit 130 to provide the safety signal processing unit 142 with an abnormality judgment timing for abnormality judgment. When the first switch unit 121 fails and the long conduction is abnormal, or the insulating isolation layer 220 detects that the local or overall temperature of the heating conductor 230 is abnormally too high, or the insulating isolation layer 220 is insulated and causes a short circuit between the conductors, the safety protection circuit 140 analyzes the voltage value output by the safety signal sampling unit 141 through the safety signal processing unit 142 to determine whether it is reasonable or whether the time of occurrence of the voltage value conforms to the abnormality judgment timing to determine the existence of the abnormality. When an abnormality exists, the safety signal processing unit 142 outputs an abnormal signal to control the heating switch circuit 120 to disconnect the heating, thereby realizing rapid power-off safety protection; when the second switch unit 122 fails and the long conduction is abnormal, the insulating isolation layer 220 will cause the resistance value between the temperature sensing conductor 210 and the heating conductor 230 to decrease or short-circuit due to the high temperature of the heating conductor 230, and the resistor R27 will heat up due to the excessive current passing through it, and the temperature fuse F1 will melt due to the heat of the resistor R27, thereby realizing safety protection and solving the problems of inaccurate temperature detection and insufficient safety protection performance of the electric heating device.

[0078] like Figure 5 Shown is another circuit diagram of an embodiment of the present application.

[0079] See also Figure 5The temperature parameter setting circuit 160 includes multiple buttons, and the differential signal processing unit 113 includes a single-chip microcomputer U6. The multiple buttons include buttons SW4, SW5, and SW6. The first ends of buttons SW4, SW5, and SW6 are commonly grounded, and the second ends of buttons SW4, SW5, and SW6 are connected to pins 11, 12, and 13 of the single-chip microcomputer U9, respectively. The output end of the AC voltage divider sampling unit 111 is connected to pin 15 of the single-chip microcomputer U9, and the output end of the temperature-sensing voltage divider sampling unit 112 is connected to pin 16 of the single-chip microcomputer U9. The temperature parameter setting program of the single-chip microcomputer U9 presets different temperature parameter values. The user sets the temperature parameter using buttons SW4, SW5, and SW6, extracts the corresponding temperature parameter value, and provides it to the single-chip microcomputer U9 for voltage differential comparison and identification processing. Pin 9 of the single-chip microcomputer U9 is also connected to the heating switch circuit 120. The single-chip microcomputer U9 can perform differential comparison and identification processing on the temperature voltage signal and the adjusted reference voltage signal.

[0080] Further, see Figure 4 Or 5, it also includes a display DS2, which is, for example, a 1602 display screen. The display DS2 can be used to display the temperature parameter setting content and the working status of the electric heating temperature control device 100.

[0081] See also Figure 5 The first switch unit 121 includes a third bidirectional thyristor TR4 and a third optical coupler OC3, and the second switch unit 122 includes a fourth bidirectional thyristor TR3, a resistor R56 and a second capacitor C9.

[0082] The first main electrode of the third bidirectional thyristor TR4 is connected to the live wire L of the AC power supply, the second main electrode of the third bidirectional thyristor TR4 is connected to the current input end of the heating conductor 230, the control electrode of the third bidirectional thyristor TR4 is connected to the first output end of the third optocoupler OC3, the second output end of the third optocoupler OC3 is connected to the first main electrode of the third bidirectional thyristor TR4, the first input end of the third optocoupler OC3 is connected to the safety protection circuit 140, and the second input end of the third optocoupler OC3 is grounded.

[0083] The first main electrode of the fourth bidirectional thyristor TR3 is connected to the current output end of the heating conductor 230, the second main electrode of the fourth bidirectional thyristor TR3 is grounded, the control electrode of the fourth bidirectional thyristor TR3 is connected to the first end of the second capacitor C9, the second end of the second capacitor C9 is connected to the first end of the resistor R56, and the second end of the resistor R56 is connected to the temperature detection circuit 110, that is, the 9th pin of the microcontroller U9.

[0084] See also Figure 5 The timed power-off temperature measurement circuit 130 can be set in the single chip microcomputer U9.

[0085] See also Figure 5 The safety signal processing unit 142 includes a single-chip microcomputer U9, a resistor R57, a resistor R58, and a diode D17, wherein the resistor R57 and the resistor R58 are connected in series, and the series node of the resistor R57 and the resistor R58 is connected to the 7th pin of the single-chip microcomputer U9. The other end of the resistor R57 is connected to the working voltage source VDD provided by the power supply circuit 150. The other end of the resistor R58 is connected to the output end of the safety signal sampling unit 141 as the input end of the safety signal processing unit 142. The diode D17 is used for overvoltage protection. Pin 7 of the microcontroller U9 is configured as an analog-to-digital (A / D) conversion channel. When the first switch unit 121 fails and remains on for an extended period of time, or the second switch unit 122 fails and remains on for an extended period of time, or the insulation barrier 220 detects that the heating conductor 230 is abnormally overheated locally or overall, or when the insulation barrier 220 is damaged, causing a short circuit between conductors, the microcontroller U9 can read the highest peak voltage value of the aforementioned abnormality and convert it into an abnormal voltage value. This voltage value is then compared with the various abnormal voltage values ​​preset in the microcontroller U9's internal program. Combined with the abnormality judgment sequence provided by the timed power-off temperature measurement circuit 130, the abnormality can be determined. When an abnormality exists, pins 6 and 9 of the microcontroller U9 output a stop heating signal to control the second switch unit 122 to disconnect heating, achieving safety protection. To improve the accuracy of abnormality detection, the microcontroller U9 determines the actual AC power supply voltage by reading the voltage value of pin 15 and adjusts the preset abnormal voltage values ​​based on the actual AC power supply voltage, thereby improving the accuracy of abnormality detection.

[0086] See also Figure 5 Specifically, the safety signal processing unit 142 also includes a resistor R59, a voltage-stabilizing diode Z3, a single-chip microcomputer U9 and its internal zero-crossing detection program to form an AC power zero-crossing detection unit, which is used to detect the zero-crossing point of the AC power supply, so that the single-chip microcomputer U9 can grasp the time of controlling the on and off of the second switch unit 122, and the single-chip microcomputer U9 can grasp the time point of reading the temperature voltage value during temperature detection or the time point of reading the abnormal voltage value during abnormality detection.

[0087] See also Figure 5Specifically, the timed power-off temperature measurement circuit 130 is located within the single-chip microcomputer U9. The single-chip microcomputer U9 includes a timed power-off temperature measurement program. This program, via pins 6 and 9 of the single-chip microcomputer U9, controls the heating switch circuit 120 to forcibly disconnect the heating circuit for a certain period of time after the heating circuit 120 is continuously on. This program provides the safety signal processing unit 142 with an abnormality detection timing sequence for abnormality detection. Simultaneously, the temperature detection circuit 110 utilizes the heating switch circuit 120 to perform temperature detection when the heating circuit is disconnected, preventing AC power from leaking through the heating conductor 230 to the insulation isolation layer 220 or the temperature-sensing conductor 210, thereby affecting the accuracy of temperature detection.

[0088] See also Figure 5 In this embodiment, the temperature detection circuit 110 employs a single-chip microcomputer U9. This performs voltage differential comparison and identification processing on the temperature voltage signal output by the output terminal of the temperature-sensing voltage-dividing sampling unit 112 and the reference voltage signal output by the output terminal of the AC voltage-dividing sampling unit 111. This prevents variations in the AC power supply voltage and operating voltage errors from affecting temperature detection accuracy. Furthermore, the single-chip microcomputer U9 performs temperature detection when the heating switch circuit 120 is disconnected from the heating function, thus preventing leakage current from the AC power supply to the temperature-sensing conductor 210 and affecting temperature detection accuracy. By employing these technical measures, the temperature changes sensed by the temperature-sensing conductor 210 can be accurately detected, achieving high-precision temperature detection and control.

[0089] In addition, the safety protection circuit 140 uses a timed power-off temperature measurement circuit 130 to provide an abnormality judgment timing for the safety signal processing unit 142 for abnormality judgment. When the first switch unit 121 fails and the long conduction is abnormal, or the insulating isolation layer 220 detects that the local or overall temperature of the heating conductor 230 is abnormally too high, or the insulating isolation layer 220 is insulated and causes a short circuit between the conductors, the safety protection circuit 140 uses the safety signal processing unit 142 to analyze whether the voltage value output by the safety signal sampling unit 141 is reasonable or whether the time of occurrence of the voltage value conforms to the abnormality judgment timing to determine the existence of an abnormality. When an abnormality exists, the safety signal processing unit 142 outputs an abnormal signal to control the heating switch circuit 120 to disconnect the heating, thereby realizing rapid power-off safety protection; when the second switch unit 122 fails and the long conduction is abnormal, the insulating isolation layer 220 will cause the resistance value between the temperature sensing conductor 210 and the heating conductor 230 to decrease or short-circuit due to the high temperature of the heating conductor 230, and the resistor R27 will heat up due to the excessive current passing through it, and the temperature fuse F1 will melt due to the heat of the resistor R27, thereby realizing safety protection and solving the problems of inaccurate temperature detection and insufficient safety protection performance of the electric heating device.

[0090] See also Figure 6In one embodiment, the heating switch circuit 120 includes a first switch unit 121 and a second switch unit 122. The temperature-sensing and voltage-dividing sampling unit 112 includes a second resistor R18. The first end of the temperature-sensing conductor 210 is connected to the live wire L of the AC power supply. The second end of the temperature-sensing conductor 210 is connected to the first end of the heating conductor 230 via the first switch unit 121. The second end of the heating conductor 230 is connected to the first end of the second resistor R18 via the second switch unit 122. The second end of the second resistor R18 is grounded. The first end of the second resistor R18 serves as the output end of the temperature-sensing and voltage-dividing sampling unit 112 and is connected to the differential signal processing unit 113. The series position of the second resistor R18 can be adjusted according to actual needs. For example, the second resistor R18 can be connected in series between the second end of the heating conductor 230 and the first end of the second switch unit 122, with the second end of the second switch unit 122 being grounded. After the series position of the second resistor R18 is changed, only the resistance values ​​of the various resistors in the temperature detection circuit 110 need to be adaptively adjusted.

[0091] It should be noted that in this embodiment, the temperature-sensing conductor 210 and the heating conductor 230 can be used for both heating and temperature sensing. By detecting the current flowing through the temperature-sensing conductor 210 and the heating conductor 230 through the temperature-sensing partial pressure sampling unit 112, the temperatures of the temperature-sensing conductor 210 and the heating conductor 230 can be monitored simultaneously.

[0092] See also Figure 6 In one embodiment, the first switch unit 121 includes a third bidirectional thyristor TR4 and a fifth bidirectional thyristor TR5.

[0093] The second main electrode of the third bidirectional thyristor TR4 is connected to the second end of the temperature-sensing conductor 210, the first main electrode of the third bidirectional thyristor TR4 is connected to the first end of the heating conductor 230, the control electrode of the third bidirectional thyristor TR4 is connected to the first main electrode of the fifth bidirectional thyristor TR5 through the resistor R55 and the capacitor C10, the second main electrode of the fifth bidirectional thyristor TR5 is grounded, and the control electrode of the fifth bidirectional thyristor TR5 is connected to the temperature detection circuit 110, that is, the 6th pin of the microcontroller U9, through the resistor R54 and the capacitor C11.

[0094] The second aspect of the embodiment of the present application provides an electric heating device, which includes the electric heating temperature control device 100 provided in the first aspect of the embodiment of the present application. The electric heating device is, for example, an electric blanket, a heating pad, an electric heating tube, or other electric heating device.

[0095] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. An electric heating temperature control device, using an AC power supply and an external heating wire, wherein the heating wire comprises a temperature-sensing conductor, an insulating isolation layer, and a heating conductor, wherein the temperature-sensing conductor is at least used to sense the temperature of the heating conductor, the insulating isolation layer is used to insulate and isolate the conductors, and the insulating isolation layer will produce a change in resistance value or cause a short circuit between the conductors when the temperature of the local or overall temperature changes, and the heating conductor is at least used for heating, characterized in that: The electric heating temperature control device comprises: Temperature detection circuit, heating switch circuit and temperature parameter setting circuit; The temperature detection circuit includes a temperature-sensing partial pressure sampling unit, an AC partial pressure sampling unit and a differential signal processing unit; The first end of the temperature-sensitive partial pressure sampling unit is connected to the second end of the temperature-sensitive conductor, the first end of the temperature-sensitive conductor is connected to the live wire of the AC power supply, the second end of the temperature-sensitive partial pressure sampling unit is grounded, and the output end of the temperature-sensitive partial pressure sampling unit is connected to the differential signal processing unit. The temperature-sensitive partial pressure sampling unit is used to convert the signal flowing through the temperature-sensitive conductor into a temperature voltage signal and output it to the differential signal processing unit; The first end of the AC voltage-dividing sampling unit is connected to the live wire of the AC power supply, the second end of the AC voltage-dividing sampling unit is grounded, the output end of the AC voltage-dividing sampling unit is connected to the differential signal processing unit, and the AC voltage-dividing sampling unit is used to convert the input signal of the AC power supply into a reference voltage signal and output it to the differential signal processing unit; The differential signal processing unit is used to perform differential comparison and identification processing on the temperature voltage signal and the reference voltage signal to suppress the influence of the AC power supply voltage change on the accuracy of temperature detection, determine the temperature of the temperature-sensing conductor and output a stop heating signal or a heating signal; The heating switch circuit is connected to the temperature detection circuit and the heating conductor, and is used to disconnect the power supply circuit of the heating conductor when receiving the stop heating signal, and to connect the power supply circuit of the heating conductor when receiving the heating signal, so as to control the heating conductor to heat or stop heating; The temperature parameter setting circuit is connected to the temperature detection circuit and is used to set temperature parameters.

2. The electric heating temperature control device according to claim 1, characterized in that: The electric heating temperature control device also includes: A safety protection circuit is connected to the heating switch circuit and the heating conductor. The safety protection circuit utilizes the characteristic of the insulating isolation layer that when the local or overall temperature changes, the resistance value will change or a short circuit can be generated between the conductors. By detecting the leakage current of the insulating isolation layer, the local or overall temperature of the heating conductor is detected. When the temperature is greater than a preset safety value, an abnormal signal is output to control the heating switch circuit to disconnect the power supply circuit of the heating conductor.

3. The electric heating temperature control device according to claim 2, characterized in that: The heating switch circuit includes a first switch unit and a second switch unit; A first end of the first switch unit is connected to the live wire of the AC power source or the second end of the temperature-sensing conductor, a second end of the first switch unit is connected to the first end of the heating conductor, a first end of the second switch unit is connected to the second end of the heating conductor, and a second end of the second switch unit is grounded or equivalently grounded; Controlling the conduction of the first switch unit and the second switch unit to connect the power supply circuit of the heating conductor; disconnecting the power supply circuit of the heating conductor by controlling the disconnection of the first switch unit or the second switch unit; By controlling the disconnection of the first switch unit and the second switch unit, the heating current at both ends of the heating conductor is disconnected, so that the safety protection circuit can more accurately detect the leakage current of the insulating isolation layer and the temperature detection circuit can more accurately detect the temperature of the temperature-sensing conductor.

4. The electric heating temperature control device according to claim 2, characterized in that: The safety protection circuit is further configured to output an abnormality signal when the temperature detection circuit operates abnormally or the heating switch circuit operates abnormally, and control the heating switch circuit to disconnect the power supply circuit of the heating conductor.

5. The electric heating temperature control device according to claim 1, characterized in that: The heating switch circuit includes a first switch unit and a second switch unit; the temperature-sensitive voltage-dividing sampling unit includes a first resistor and a second resistor, the first end of the first resistor is connected to the output end of the temperature-sensitive conductor using a diode or directly, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is grounded, and the series node of the first resistor and the second resistor is connected to the differential signal processing unit as the output end of the temperature-sensitive voltage-dividing sampling unit; or, the temperature-sensitive voltage-dividing sampling unit includes a second resistor, the first end of the heating conductor is connected to the output end of the temperature-sensitive conductor through the first switch unit, and the heating conductor The second end of the body is connected to the first end of the second resistor through the second switching unit, the second end of the second resistor is grounded, and the first end of the second resistor is also connected to the differential signal processing unit as the output end of the temperature-sensitive voltage-dividing sampling unit; the AC voltage-dividing sampling unit includes a third resistor and a fourth resistor, the first end of the third resistor is connected to the live wire of the AC power supply using a diode or directly, the second end of the third resistor is connected to the first end of the fourth resistor, the second end of the fourth resistor is grounded, and the series connection node of the third resistor and the fourth resistor serves as the output end of the AC voltage-dividing sampling unit and is connected to the differential signal processing unit; The diodes used in the temperature-sensitive voltage-dividing sampling unit and the AC voltage-dividing sampling unit are both used to simultaneously intercept the voltage of the positive half cycle or the negative half cycle of the AC power supply for voltage-dividing sampling.

6. The electric heating temperature control device according to claim 1, characterized in that: The differential signal processing unit includes a first voltage comparator and a second voltage comparator, wherein a first input terminal of the first voltage comparator is connected to an output terminal of the temperature-sensing voltage-dividing sampling unit, a second input terminal of the first voltage comparator is connected to an output terminal of the AC voltage-dividing sampling unit, an output terminal of the first voltage comparator is connected to a second input terminal of the second voltage comparator, a first input terminal of the second voltage comparator is connected to a voltage source, and an output terminal of the second voltage comparator is connected to the heating switch circuit; Alternatively, the differential signal processing unit includes a third voltage comparator and a single-chip microcomputer, wherein a first input terminal of the third voltage comparator is connected to an output terminal of the temperature-sensing voltage-dividing sampling unit, a second input terminal of the third voltage comparator is connected to an output terminal of the AC voltage-dividing sampling unit, an output terminal of the third voltage comparator is connected to the single-chip microcomputer, and the single-chip microcomputer is further connected to the heating switch circuit; Alternatively, the differential signal processing unit includes a single-chip microcomputer, the output end of the temperature-sensing voltage-dividing sampling unit is connected to the first analog-to-digital conversion port of the single-chip microcomputer, the output end of the AC voltage-dividing sampling unit is connected to the second analog-to-digital conversion port of the single-chip microcomputer, and the single-chip microcomputer is also connected to the heating switch circuit.

7. The electric heating temperature control device according to claim 2, characterized in that: The safety protection circuit includes a safety signal sampling unit and a safety signal processing unit; The first end of the safety signal sampling unit is connected to the second end of the heating conductor, and the second end of the safety signal sampling unit is grounded or connected to the voltage output end of the power supply circuit. The safety signal sampling unit is used to convert the current signal flowing through the unit into a safety voltage signal and output it to the safety signal processing unit; The safety signal processing unit is connected to the heating switch circuit, and performs abnormality analysis and judgment based on the received abnormality judgment timing and the safety voltage signal. When an abnormality exists, the safety signal processing unit outputs an abnormality signal to the heating switch circuit; The heating switch circuit is also connected to the safety signal processing unit, and the heating switch circuit is further configured to disconnect the power supply circuit of the heating conductor when receiving the abnormal signal.

8. The electric heating temperature control device according to claim 1, characterized in that: The electric heating temperature control device also includes: The timed power-off temperature measurement circuit is used to directly or indirectly control the heating switch circuit to forcibly disconnect the heating for a certain period of time after each continuous heating period. The electric heating temperature control device uses the heating switch circuit to perform temperature detection when the heating is disconnected to prevent the AC power from leaking to the temperature-sensing conductor through the heating conductor and the insulating isolation layer, thereby affecting the accuracy of temperature detection.

9. The electric heating temperature control device according to claim 2, characterized in that: The temperature detection circuit performs temperature detection during the positive half cycle of the AC power supply, and the safety protection circuit performs abnormality detection during the negative half cycle of the AC power supply; or the temperature detection circuit performs temperature detection during the negative half cycle of the AC power supply, and the safety protection circuit performs abnormality detection during the positive half cycle of the AC power supply; this is used to avoid conflict between the temperature detection circuit and the safety protection circuit during operation.

10. An electric heating device, characterized in that: The electric heating temperature control device comprises any one of claims 1 to 9.

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