An integrated heating control and simultaneous impedance measurement circuit

Abstract

The present application relates to heating wire state measurement technical field, specifically to a kind of integrated heating control and synchronous impedance measurement circuit, including heating circuit, on-off control circuit, temperature measurement circuit and heating wire impedance measurement circuit, heating circuit includes at least one heating wire and thermistor, heating wire and thermistor are arranged in series and encapsulated into an integrated, on-off control circuit includes first control switch, second control switch, third control switch and fourth control switch.The present application can realize the real-time temperature measurement of heating wire by cooperating temperature measurement circuit with the thermistor arranged in series with heating wire, can realize the real-time sampling of heating wire working circuit by heating wire impedance measurement circuit, and further realize the calculation of heating wire impedance value, to determine the working state of heating wire, when heating wire fails, can timely output alarm signal, and cooperating diagnostic logic can also realize the diagnostic analysis of heating wire failure cause.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heating wire state measurement, and particularly relates to an integrated heating control and synchronous impedance measurement circuit. BACKGROUND

[0002] Heating wires are widely used in daily life and industrial production as common electric heating conversion equipment. In order to ensure safety and production, strict temperature management is required for the heating wires. A conventional heating control and temperature measurement circuit generally uses a heating wire to heat and configures a matching sensor circuit such as a K-type thermocouple or a PT100 temperature measuring element to measure temperature. In operation, the conventional heating control and temperature measurement circuit generally needs to heat the heating wire through an excitation power supply and uses an independent thermocouple temperature measurement probe to closely contact the heating wire to collect the working temperature of the heating wire. In actual operation, in order to improve the safety factor, certain electrical insulation measures are required. After the two leads of the temperature measuring element are led out, they are connected to the measurement circuit. The signal lines generally have multiple leads. For example, when a thermocouple is used for temperature measurement control, two heating control signal lines of the heating wire are connected to two ends of the excitation power supply. A switch is connected in series in the loop for heating control of the heating wire. The two leads of the thermocouple are connected to the thermoelectric potential of the thermocouple through the measurement conversion circuit. Different measurement temperatures are obtained according to the different thermoelectric potentials of the thermocouple. A total of four leads are required. In the operation of installing a large number of heating wires, the leading of multiple signal lines and control lines makes it easy for users to connect the wrong lines when wiring, which has high wiring difficulty and complex assembly process.

[0003] Meanwhile, the conventional temperature measurement circuit cannot measure the impedance of the heating wire. When the heating wire is short-circuited or open-circuited, the excitation power supply will be damaged. When the heating wire is open-circuited, the heating circuit will fail. Although the temperature measurement circuit can sense the temperature abnormality, it can only feedback the abnormality of the heating control circuit after the temperature deviates greatly, which is a strong lag link and cannot determine whether the switch in the heating control circuit is damaged or the heating wire itself is faulty, which has great safety hazards. SUMMARY

[0004] The present application solves the technical problem that the existing heating circuit and temperature measurement circuit are separated from each other, multiple signal lines are led out, it is easy to connect the wrong lines, has high wiring difficulty and complex assembly process, and cannot detect the fault in time when the heating circuit fails, needs to feedback the abnormality of the heating control circuit after the temperature deviates greatly, and cannot detect the fault cause.

[0005] To solve the above technical problems, the application adopts the following technical scheme: an integrated heating control and synchronous impedance measurement circuit, comprising a heating circuit, a on-off control circuit, a temperature measurement circuit and a heating wire impedance measurement circuit, the heating circuit comprising at least one heating wire and a thermistor, the heating wire and the thermistor being arranged in series and packaged into an integrated body, the on-off control circuit comprising a first control switch, a second control switch, a third control switch and a fourth control switch, the first end of the heating circuit being connected to a corresponding first power supply for heating the heating wire through the first control switch and grounded through the second control switch, the second end of the heating circuit being connected to a second power supply for measuring the temperature of the heating wire through the temperature measurement circuit and the third control switch and grounded through the fourth control switch and the heating wire impedance measurement circuit.

[0006] In operation, the real-time temperature measurement of the heating wire can be realized by the thermistor arranged in series with the heating wire and cooperating with the temperature measurement circuit, the real-time sampling of the heating wire working circuit can be realized by the heating wire impedance measurement circuit, and the calculation of the impedance value of the heating wire can be realized, so as to determine the working state of the heating wire, and when the heating wire fails, an alarm signal can be output in time, and the diagnosis and analysis of the failure cause of the heating wire can be realized by cooperating with the diagnosis logic.

[0007] As a preferred, the heating circuit further comprises a diode D2, the cathode of the diode D2 being connected to one end of the first power supply connected with the thermistor, and the anode of the diode D2 being connected to one end of the second power supply connected with the thermistor.

[0008] As a preferred, the temperature measurement circuit comprises an operational amplifier U1, a resistor R3, a resistor R5 and a capacitor C1, the second end of the heating circuit being connected to the second power supply through the resistor R3 and the third control switch and connected to the non-inverting input terminal of the operational amplifier U1 through the resistor R5, the non-inverting input terminal of the operational amplifier U1 being grounded through the capacitor C1, the output terminal of the operational amplifier U1 being connected to the corresponding main control module to measure the temperature of the heating module and connected to the inverting input terminal of the operational amplifier U1.

[0009] As a preferred, the heating wire impedance measurement circuit comprises a resistor Rx, a resistor R6, a resistor R7, a resistor R8, a resistor R9 and an operational amplifier U2, the first end of the resistor Rx being connected to the second end of the heating circuit through the fourth control switch and connected to the non-inverting input terminal of the operational amplifier U2 through the resistor R6, the non-inverting input terminal of the operational amplifier U2 being connected to a reference voltage through the resistor R7, the second end of the resistor Rx being grounded, the inverting input terminal of the operational amplifier U2 being connected to the output terminal of the operational amplifier U2 through the resistor R9 and grounded through the resistor R8, and the output terminal of the operational amplifier U2 being connected to the corresponding main control module to measure the impedance value of the heating wire.

[0010] Preferably, the control terminals of the first control switch, the second control switch, the third control switch, and the fourth control switch are all connected to the corresponding main control module.

[0011] The beneficial technical effects of this invention include:

[0012] This invention enables real-time temperature measurement of the heating wire by using a thermistor arranged in series with the heating wire and a temperature measurement circuit. It also enables real-time sampling of the heating wire's operating circuit through a heating wire impedance measurement circuit, thereby calculating the heating wire's impedance value and determining the heating wire's operating status. When the heating wire malfunctions, it can output an alarm signal in a timely manner. In conjunction with diagnostic logic, it can also diagnose and analyze the cause of the heating wire malfunction.

[0013] Other features and advantages of the present invention will be disclosed in detail in the following detailed description and accompanying drawings. Attached Figure Description

[0014] The invention will be further described below with reference to the accompanying drawings:

[0015] Figure 1 This is a circuit structure diagram of an integrated heating control and synchronous impedance measurement circuit.

[0016] Figure 2 This is the working wiring diagram of an integrated heating control and synchronous impedance measurement circuit. Figure 1 (Temperature measurement status);

[0017] Figure 3 This is the working wiring diagram of an integrated heating control and synchronous impedance measurement circuit. Figure 2 (Heating wire impedance measurement status);

[0018] Figure 4 This is a circuit diagram of the heating wire impedance measurement circuit. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0020] In the following description, terms such as “inner,” “outer,” “upper,” “lower,” “left,” and “right” are used only to indicate orientation or positional relationship for the convenience of describing the embodiments and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0021] Please see Figure 1 This embodiment discloses an integrated heating control and synchronous impedance measurement circuit, including a heating circuit 1, an on / off control circuit 2, a temperature measurement circuit 3, and a heating wire impedance measurement circuit 4. The following is a detailed description with reference to the accompanying drawings.

[0022] Please see Figures 1 to 4 In this embodiment, the heating circuit 1 includes at least one heating wire 11 and a thermistor 12. The heating wire 11 and the thermistor 12 are arranged in series and encapsulated as one unit. Preferably, two heating wires 11 can be used, which are connected in series through the thermistor 12 and the thermistor 12 is arranged in the middle of the two heating wires 11. The heating wire 11 and the thermistor 12 are encapsulated as one unit, resulting in a compact structure. In this case, the heating circuit 1 has only two leads, which can realize temperature measurement and heating wire 11 impedance measurement regardless of whether they are connected in the correct or reverse direction, making installation convenient. The on / off control circuit 2 includes a first control switch, a second control switch, a third control switch, and a fourth control switch. The first end of the heating circuit 1 is connected to the corresponding first power supply for heating the heating wire 11 through the first control switch and is grounded through the second control switch. The second end of the heating circuit 1 is connected to the second power supply for measuring the temperature of the heating wire 11 through the temperature measurement circuit 3 and the third control switch and is grounded through the fourth control switch and the heating wire impedance measurement circuit 4.

[0023] In this embodiment, the real-time temperature measurement of the heating wire 11 can be achieved by the thermistor 12 arranged in series with the heating wire 11 and the temperature measurement circuit 3. The real-time sampling of the working circuit of the heating wire 11 can be achieved by the heating wire impedance measurement circuit 4, thereby realizing the calculation of the impedance value of the heating wire 11 and thus determining the working status of the heating wire 11. When the heating wire 11 malfunctions, an alarm signal can be output in time. With the help of diagnostic logic, the cause of the heating wire 11 malfunction can also be diagnosed and analyzed.

[0024] In a specific implementation, the heating circuit 1 also includes a diode D2. The cathode of the diode D2 is connected to one end of the thermistor 12 connected to the first power supply, and the anode of the diode D2 is connected to one end of the thermistor 12 connected to the second power supply.

[0025] Preferably, the temperature measurement circuit 3 includes an operational amplifier U1, resistors R3 and R5, and capacitor C1. The second terminal of the heating circuit 1 is connected to the second power supply through resistor R3 and the third control switch, and is connected to the non-inverting input terminal of the operational amplifier U1 through resistor R5. The non-inverting input terminal of the operational amplifier U1 is grounded through capacitor C1. The output terminal of the operational amplifier U1 is connected to the corresponding main control module to measure the temperature of the heating module, and is connected to the inverting input terminal of the operational amplifier U1.

[0026] In this embodiment, the heating wire impedance measurement circuit 4 includes resistors Rx, R6, R7, R8, and R9, as well as operational amplifier U2. The first end of resistor Rx is connected to the second end of heating circuit 1 through a fourth control switch, and is connected to the non-inverting input of operational amplifier U2 through resistor R6. The non-inverting input of operational amplifier U2 is connected to a reference voltage through resistor R7. The second end of resistor Rx is grounded. The inverting input of operational amplifier U2 is connected to the output of operational amplifier U2 through resistor R9, and is grounded through resistor R8. The output of operational amplifier U2 is connected to the corresponding main control module to measure the impedance value of heating wire 11.

[0027] Preferably, the control terminals of the first, second, third, and fourth control switches are all connected to the corresponding main control modules. During operation, the main control module controls the first and fourth control switches to be turned on, while the second and third control switches are turned off. The current signal, thus the first power supply, flows through the first control switch, heating wire 11, and diode D2, finally reaching the reference ground via resistor Rx, forming a current loop. Operational amplifier U2 samples the current signal flowing through heating wire 11 at resistor Rx. After amplification by operational amplifier U2, an impedance detection voltage is obtained, and the impedance value of heating wire 11 can be deduced. Specifically, when the detected sampled current signal value is zero, it can be inferred that heating wire 11 is open-circuited; when the detected sampled current value exceeds a preset threshold, it can be inferred that heating wire 11 is short-circuited, and a fault diagnosis alarm is triggered. During temperature measurement, the main control module controls the third... When the control switch and the second control switch are turned on, and the first control switch and the fourth control switch are turned off, the current signal flows from the second power supply through the third control switch, resistor R3, heating wire 11 and thermistor 12, and finally through the second control switch to the reference ground, forming a current loop. The voltage of the second power supply passes through resistor R3, thermistor 12 and heating wire 11 to form a first temperature measurement voltage at the second terminal of heating circuit 1. The temperature measurement voltage is filtered by resistor R5 and capacitor C1, and then passed through operational amplifier U1 to form a second temperature measurement voltage. After the corresponding main control module processes the second temperature measurement voltage, the real-time resistance value of thermistor 12 is obtained, and the temperature value of heating circuit 1 is calculated. In this way, the temperature measurement and fault detection of heating circuit 1 with only two leads can be completed. Through the integrated heating circuit 1, the wiring difficulty can be greatly reduced and the assembly process can be optimized.

[0028] In practical implementation, the resistance values ​​of resistors R6 and R7 are equal, and the resistance values ​​of resistors R8 and R9 are equal. After acquiring the sampling voltage Vin across resistor Rx, the impedance detection voltage is calculated using the following formula:

[0029] ;

[0030] in: The actual impedance of heating wire 11 This is the first power supply voltage. The impedance detection voltage, For reference voltage, The resistance value Rx is used to measure the impedance of the heating wire 11 online in real time during operation. This allows for timely detection of the fault status of the heating wire 11 without the need for additional compensation circuits. When a fault occurs, cutting off the first or third control switch can prevent the fault from escalating further and avoid accidents, making it safe and efficient.

[0031] The beneficial technical effects of this embodiment include: the present invention can realize real-time temperature measurement of the heating wire by using a thermistor arranged in series with the heating wire and a temperature measurement circuit, and can realize real-time sampling of the heating wire working circuit by using a heating wire impedance measurement circuit, thereby realizing the calculation of the heating wire impedance value, thus determining the working status of the heating wire, and can output an alarm signal in time when the heating wire malfunctions. In conjunction with diagnostic logic, it can also realize the diagnosis and analysis of the cause of the heating wire malfunction.

[0032] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. An integrated heating control and synchronous impedance measurement circuit, characterized in that: The device includes a heating circuit (1), an on / off control circuit (2), a temperature measurement circuit (3), and a heating wire impedance measurement circuit (4). The heating circuit (1) includes at least one heating wire (11) and a thermistor (12). The heating wire (11) and the thermistor (12) are arranged in series and encapsulated as a whole. The on / off control circuit (2) includes a first control switch, a second control switch, a third control switch, and a fourth control switch. The first end of the heating circuit (1) is connected to a first power supply for heating the heating wire (11) through the first control switch and is grounded through the second control switch. The second end of the heating circuit (1) is connected to a second power supply for measuring the temperature of the heating wire (11) through the temperature measurement circuit (3) and the third control switch and is grounded through the fourth control switch and the heating wire impedance measurement circuit (4). During operation, the main control module controls the first and fourth control switches to be turned on, while the second and third control switches are turned off. During temperature measurement, the main control module controls the third and second control switches to be turned on, while the first and fourth control switches are turned off.

2. The integrated heating control and synchronous impedance measurement circuit according to claim 1, characterized in that: The heating circuit (1) further includes a diode D2, the cathode of the diode D2 is connected to one end of the thermistor (12) connected to the first power supply, and the anode of the diode D2 is connected to one end of the thermistor (12) connected to the second power supply.

3. The integrated heating control and synchronous impedance measurement circuit according to claim 1, characterized in that: The temperature measurement circuit (3) includes an operational amplifier U1, a resistor R3, a resistor R5, and a capacitor C1. The second end of the heating circuit (1) is connected to the second power supply through the resistor R3 and the third control switch, and is connected to the non-inverting input of the operational amplifier U1 through the resistor R5. The non-inverting input of the operational amplifier U1 is grounded through the capacitor C1. The output of the operational amplifier U1 is connected to the corresponding main control module to measure the temperature of the heating module, and is connected to the inverting input of the operational amplifier U1.

4. The integrated heating control and synchronous impedance measurement circuit according to claim 1, characterized in that: The heating wire impedance measurement circuit (4) includes resistors Rx, R6, R7, R8, R9 and operational amplifier U2. The first end of resistor Rx is connected to the second end of heating circuit (1) through the fourth control switch and is connected to the non-inverting input of operational amplifier U2 through resistor R6. The non-inverting input of operational amplifier U2 is connected to the reference voltage through resistor R7. The second end of resistor Rx is grounded. The inverting input of operational amplifier U2 is connected to the output of operational amplifier U2 through resistor R9 and is grounded through resistor R8. The output of operational amplifier U2 is connected to the corresponding main control module to measure the impedance value of heating wire (11).

5. The integrated heating control and synchronous impedance measurement circuit according to claim 1, characterized in that: The control terminals of the first control switch, the second control switch, the third control switch, and the fourth control switch are all connected to the corresponding main control module.

Images