Temperature control device and method for semiconductor process gas pipeline

Abstract

The invention provides a temperature control device and method for a semiconductor process gas pipeline. The temperature control device comprises a temperature information receiving circuit, a heating information output circuit, an arc control circuit and a control circuit, the temperature information receiving circuit is electrically connected with the temperature measuring device and is configured to receive the temperature information sent by the temperature measuring device; the heating information output circuit is electrically connected with the heating device and is configured to control on-off of power supply to the heating device; the electric arc control circuit is electrically connected with the heating information output circuit and is configured to provide a current follow current path when the heating information output circuit is disconnected with a load so as to eliminate electric arcs; and the control circuit is electrically connected with the temperature information receiving circuit, the heating information output circuit and the arc control circuit separately. According to the invention, the arc generated when the relay contact is disconnected can be avoided, the service life of the relay is prolonged, and the safety and reliability of the temperature control device are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical control, and more particularly, to a temperature control device and method for a semiconductor process gas pipeline. BACKGROUND

[0002] In the field of semiconductor industry control, relays are widely used in various devices for controlling the on-off of loads. The traditional relay control system usually issues instructions through a master control chip, such as an MCU or a CPU, and uses an isolation driving circuit, such as an optical coupler or a transistor, to connect the master control chip with a direct current power supply, so as to realize the on-off control of the relay coil. When the relay coil is powered on, a magnetic field is generated to drive the armature to act, so that the contacts are closed and the load current forms a loop through the contacts; when the relay coil is powered off, the contacts are quickly disconnected under the action of the spring, thereby cutting off the load current. This control mode realizes precise and isolated control of weak current on strong current, and is widely used in the control of high-power motors, lighting systems and other loads.

[0003] However, in actual application, the relay contacts will face many challenges when breaking a large current. When the current to be broken between the contacts is far beyond the rated capacity, or when an overload current passes through the contacts for a long time in the closed state, strong electric arcs will be generated on the surface of the contacts. Such electric arcs not only generate high-temperature plasma of thousands of degrees Celsius, but also seriously melt and vaporize the metal material on the surface of the contacts, resulting in rough and uneven surface of the contacts, and finally the melted and welded contacts are stuck together after cooling. At this time, even if the control circuit issues instructions and the relay coil is powered off to release, the welded contacts cannot be physically separated, resulting in a failure state that the coil is not attracted, but the contacts are always on. In the temperature controller, this failure will cause the heater to be continuously powered on and uncontrollably heated, so that the system temperature far exceeds the set value, not only damaging the temperature controller output unit, but also possibly burning the heater itself, and even causing a safety accident. Therefore, this overcurrent damage of the relay cuts off the connection between the control logic and the execution end of the temperature controller, resulting in the loss of control of the entire system.

[0004] In the implementation process of the embodiments of the present application, at least the following problems or defects exist in the prior art: When the relay contacts break a large current, electric arcs are easily generated, which causes the contacts to be ablated and welded and stuck, seriously affecting the service life and reliability of the relay, and further affecting the safety and stability of the entire system. SUMMARY

[0005] The present application provides a temperature control device and method for a semiconductor process gas pipeline.

[0006] In a first aspect of the present application, a temperature control device for a semiconductor process gas pipeline is applied to a temperature control system, the temperature control system comprising an externally connected heating device and a temperature measuring device, characterized in that the temperature control device comprises: A temperature information receiving circuit, electrically connected to the temperature measuring device, is configured to receive temperature information sent by the temperature measuring device. A heating information output circuit, electrically connected to the heating device, is configured to control the on / off state of power supply to the heating device; An arc control circuit, electrically connected to the heating information output circuit, is configured to provide a current follow-through path when the heating information output circuit disconnects the load, so as to eliminate the arc. The control circuit, which is electrically connected to the temperature information receiving circuit, the heating information output circuit, and the arc control circuit respectively, is configured to receive and process the temperature information. Based on the processing results and the preset temperature threshold, a control signal is output to the heating information output circuit to control the power supply status of the heating device; before the heating information output circuit is disconnected, a trigger signal is first output to the arc control circuit to turn on the thyristor therein, so as to realize the arc-free transfer and interruption of the heating circuit current.

[0007] Furthermore, the heating information output circuit includes: A first driving unit and a second driving unit are connected, with the input terminals of the first driving unit and the second driving unit respectively connected to the first control terminal and the second control terminal of the control circuit, and the output terminals of the first driving unit and the second driving unit respectively electrically connected to the heating device.

[0008] Furthermore, the first driving unit includes a first transistor, a first base resistor, and a first relay, and the second driving unit includes a second transistor, a second base resistor, and a second relay; The base of the first transistor is connected to the first control port through the first base resistor, the emitter is grounded, and the collector is connected to the first end of the first relay coil. The base of the second transistor is connected to the second control port through the second base resistor, the emitter is grounded, and the collector is connected to the first end of the second relay coil; The first relay coil and the second relay are respectively connected in reverse parallel with a first freewheeling diode and a second freewheeling diode; One end of the first driving unit is electrically connected to one end of the second driving unit.

[0009] Furthermore, the heating information output circuit also includes a third driving unit; The third driving unit includes a third transistor and a third base resistor; The base of the third transistor is connected to the third control port of the control circuit through the third base resistor, the emitter is grounded, and the collector is connected to the second transistor.

[0010] Furthermore, the arc control circuit includes a bidirectional thyristor and an optocoupler drive unit; The bidirectional thyristor is connected in parallel across the two ends of the second relay. Its gate receives the drive signal from the optocoupler drive unit, which is used to provide continuous power to the heating device when the second relay is disconnected, and to transfer the electric arc generated when the second relay is disconnected.

[0011] Furthermore, the input terminal of the optocoupler driving unit is connected to the fourth control port of the control circuit, and the output terminal is connected to the gate of the bidirectional thyristor, for triggering the bidirectional thyristor to conduct under the control of the control circuit.

[0012] Furthermore, the optocoupler driving unit includes a thyristor driving optocoupler, a gate current limiting resistor, and a fourth transistor; The input-side anode of the thyristor-driven optocoupler and the fourth transistor are connected in series to the fourth control port of the control circuit, and the cathode is grounded. The first end of the output side of the thyristor driver optocoupler is connected to the gate of the bidirectional thyristor through the gate current limiting resistor, and the second end of the output side is connected to the second main terminal of the bidirectional thyristor.

[0013] Furthermore, the optocoupler driving unit also includes a buffer resistor; The buffer resistor is connected between the gate of the bidirectional thyristor and its second main terminal.

[0014] Furthermore, the heating information output circuit and the arc control circuit are mounted on the power board of the temperature control device; The control circuit and the temperature information receiving circuit are mounted on the main control board of the temperature control device. The main control board and the power board are electrically connected to achieve signal interaction.

[0015] In a second aspect of the invention, a temperature control method for a semiconductor process gas pipeline is provided, comprising: S1: The temperature of the gas pipeline is detected by the temperature measuring unit, and a temperature signal is generated and transmitted to the control unit; S2: The control unit receives and processes the temperature signal, and determines the relationship between the current temperature and the preset first threshold and second threshold. S3: If the temperature is determined to be below the first threshold, the control unit outputs a control signal to close the contacts of the first and second relays in the heating information output circuit, and the AC power supply supplies power to the heater. S4: If the temperature is determined to be equal to or greater than the first threshold, the control unit first outputs a signal to trigger the bidirectional thyristor in the arc extinguishing circuit to conduct, and then outputs a control signal to disconnect the contacts of the second relay, so that the heating current is transferred to the bidirectional thyristor. S5: If the temperature drops to the second threshold, the control unit outputs a control signal to close the contacts of the second relay, the bidirectional thyristor turns off at the subsequent AC zero-crossing point, and the heater resumes power supply; S6: Repeat steps S1-S5 to achieve closed-loop control of gas pipeline temperature and arc-free disconnection of relay.

[0016] The embodiments of the present invention have at least the following beneficial effects: By connecting a bidirectional thyristor in parallel with relay contacts and establishing coordinated operation logic between the arc control circuit and the heating information output circuit, a smooth, arc-free transfer of load current during disconnection is achieved. When the temperature reaches the set upper limit and the heating device needs to be disconnected, the control circuit first triggers the bidirectional thyristor in the arc control circuit to conduct, and then disconnects the relay contacts in the heating information output circuit, allowing the current to continue flowing until the AC current crosses zero and the thyristor automatically turns off. This process fundamentally avoids the arc generated by the relay contacts when interrupting large currents, significantly reducing the risk of contact erosion and welding, thereby greatly extending the service life of the relay and improving the long-term operational reliability and stability of the entire temperature control system.

[0017] This invention coordinates the temperature information receiving circuit, the heating information output circuit, and the arc control circuit through a control circuit. It controls the on / off state of the relay coil through a multi-channel drive unit and triggers the bidirectional thyristor through an optocoupler isolation unit. This achieves reliable isolation and precise timing control between strong and weak currents, enabling stable operation in complex electromagnetic environments such as the semiconductor industry. It effectively solves the arcing problem caused by the direct disconnection of the load by traditional relays and improves the overall control performance and safety of the system. Attached Figure Description

[0018] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of the invention are illustrated in the drawings by way of example, not limitation, in which: Figure 1 This is a schematic diagram of a temperature control system structure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a heating information output circuit according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the optocoupler drive and thyristor trigger circuit in an arc control circuit according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the external interface and application connection of a temperature control device provided in an embodiment of the present invention. Detailed Implementation

[0019] The principles and spirit of the invention will now be described with reference to several exemplary embodiments. It should be understood that these embodiments are provided merely to enable those skilled in the art to better understand and implement the invention, and are not intended to limit the scope of the invention in any way. Rather, these embodiments are provided to make the invention more thorough and complete, and to fully convey the scope of the invention to those skilled in the art.

[0020] The following is for reference. Figure 1 , Figure 1 This is a system structure block diagram provided according to an embodiment of the present invention. For example... Figure 1 As shown, a device for temperature control of a semiconductor gas pipeline is applied to a temperature control system including an external heating device and a temperature measuring device. The temperature control device includes: a temperature information receiving circuit, a heating information output circuit, an arc control circuit, and a control circuit.

[0021] The temperature information receiving circuit is electrically connected to the temperature measuring device and is configured to receive temperature information sent by the temperature measuring device. The heating information output circuit is electrically connected to the heating device and is configured to control the on / off switching of power supply to the heating device. The arc control circuit is electrically connected to the heating information output circuit and is configured to provide a current follow-through path to eliminate the arc when the load of the heating information output circuit is disconnected. The control circuit is electrically connected to the temperature information receiving circuit, the heating information output circuit, and the arc control circuit respectively, and is configured to receive and process the temperature information, and output corresponding control signals according to the processing results and preset temperature thresholds.

[0022] like Figure 2As shown, the heating information output circuit includes a first driving unit, a second driving unit, and a third driving unit. The first driving unit includes a first transistor Q1 and a first base resistor R1. The base of the first transistor Q1 is connected to the first control port P1-11 of the control chip through the first base resistor R1, and its collector is connected to the first terminal of the first relay K1. The second driving unit includes a second transistor Q2 and a second base resistor R2. The base of the second transistor Q2 is connected to the second control port P1-12 of the control circuit through the second base resistor R2, its emitter is grounded, and its collector is connected to the first terminal of the second relay K2. A first freewheeling diode D1 and a second freewheeling diode D2 are connected in reverse parallel across the terminals of the first relay K1 and the second relay K2, respectively, to provide a current release path when the relay coil is de-energized. The second terminal of the first relay K1 is electrically connected to the second terminal of the second relay K2. The first driving unit and the second driving unit are respectively connected to the same heating device.

[0023] The third driving unit includes a third transistor Q3 and a third base resistor R3. The base of the third transistor Q3 is connected to the second control port P1-13 of the control chip through the third base resistor R3, the emitter is grounded, and the collector is electrically connected to the emitter of the first transistor.

[0024] like Figure 3 As shown, the arc control circuit includes a bidirectional thyristor U9 and its trigger optocoupler U1. The bidirectional thyristor U9 is connected in parallel across the second relay K2 to provide a current freewheeling path. Specifically, its first main terminal is connected to the load-side node ACL1 of the second relay K2 contact in the heating information output circuit, and its second main terminal is connected to the load-side node ACN1 of the first relay K1 contact.

[0025] The optocoupler driving unit is used to control the conduction of the bidirectional thyristor U9. It includes a thyristor driving optocoupler U1 and a gate current limiting resistor R9. The anode of the input side of the thyristor driving optocoupler U1 is connected to the fourth control port P1-14 of the control chip, and the cathode is grounded. When the control circuit needs to trigger the arc control function, a high-level signal with a pulse width of not less than 20ms is output from the fourth control port P1-14. This signal illuminates the LED on the input side of the optocoupler U1, and through optocoupler, turns on the bidirectional thyristor on the output side. The first terminal of the output side of the thyristor driving optocoupler U1 is connected to the gate of the external power bidirectional thyristor U9 through the gate current limiting resistor R9, and the second terminal is connected to the second main terminal of the bidirectional thyristor U9. Thus, the conduction of the secondary side of the thyristor driving optocoupler U1 provides a driving current to the gate of the bidirectional thyristor U9, enabling it to conduct. Furthermore, a buffer resistor R13 is connected between the gate of the bidirectional thyristor U9 and the second main terminal to absorb interference and stabilize the triggering.

[0026] Combination Figure 2 , Figure 3 As shown, when the load needs to be disconnected, the control circuit is configured to perform the following timing operations: first, the bidirectional thyristor U9 is triggered to conduct through the optocoupler drive unit; then, the contacts of the second relay K2 are controlled to open; at this time, the load current is transferred from the contacts of the second relay K2 to the already conducting bidirectional thyristor U9 to continue flowing, realizing arc-free follow current; until the AC current naturally crosses zero, the bidirectional thyristor U9 turns off by itself, and the load is safely disconnected.

[0027] For example, the explanation is based on specific temperature thresholds. For instance, the first threshold for preset temperature information in a semiconductor gas pipeline is 108 degrees Celsius, and the second threshold is 102 degrees Celsius.

[0028] During system startup and heating, the temperature control device begins operation, and the temperature measuring device continuously monitors the pipe temperature and sends the data to the control circuit via the temperature information receiving circuit. When the control circuit determines that the temperature is below the first threshold of 108 degrees Celsius, the control chip outputs a high-level signal through the first control port P1-11 and the second control port P1-12, turning on the first transistor Q1 and the second transistor Q2. This, in turn, drives the first relay K1 and the second relay K2 in the heating information output circuit to close their contacts, thereby outputting operating current to the heating device, which continuously heats the semiconductor gas pipe.

[0029] Temperature Limit Reached and Arc Extinguishing Phase: When the temperature measuring device detects that the internal temperature of the pipe reaches or exceeds 108 degrees Celsius, the control circuit executes the arc extinguishing logic. First, the control chip outputs a trigger signal through the fourth control port P1-14 to the thyristor drive optocoupler U1 in the optocoupler drive unit, triggering the bidirectional thyristor U9 to conduct. After the bidirectional thyristor U9 reliably conducts, the control chip removes the high-level signal from the second control port P1-12, and the second relay K2 in the heating information output circuit is de-energized, its contacts opening. At this time, the freewheeling diode D1 connected in parallel across the coil of K2 provides a release path for the residual current in the coil, completing the arc extinguishing and protecting the drive circuit.

[0030] At this point, the load current is transferred from its original path through the second relay K2 contact to the bidirectional thyristor U9 to continue flowing. The heating device stops directly drawing current from the power supply due to the main circuit being disconnected, but a freewheeling current is formed through the bidirectional thyristor U9 in the arc control circuit. When the AC current naturally crosses zero, a cycle typically lasts 20ms, the bidirectional thyristor U9 automatically turns off, the freewheeling process ends, and the heating device completely stops working. In practical applications, due to thermal inertia, the temperature inside the semiconductor gas pipe will initially rise slightly and then begin to decrease.

[0031] Temperature Drop and Reheating Recovery Phase: When the temperature measuring device detects that the internal temperature of the pipe has dropped to the second threshold of 102 degrees Celsius, the control circuit executes the heating recovery logic. The control chip re-outputs a high-level signal through the second control port P1-12, turning on the third transistor Q9, which in turn drives the coil of the second relay K2 to close its contacts. This reconnects the heating information output circuit, providing continuous current to the heating device once again. The heating device resumes power supply, heating the pipe.

[0032] When the temperature reaches 108 degrees again, the control circuit will again control the power supply to power the arc control circuit, repeating the above process. Through the continuous cycle of heating, arc extinguishing, stopping heating, and resuming heating, the gas pipeline temperature is precisely maintained within the preset range.

[0033] In some embodiments, the temperature control device is further provided with a third threshold. When the temperature inside the gas pipeline is detected to be higher than the third threshold, a trigger signal is output to the third drive unit through the third control port P1-13 of the main control circuit to control the first relay K1 to open and stop supplying power to the heating resistor, so as to prevent the heating device from overheating the semiconductor process gas pipeline.

[0034] In some embodiments, a method for temperature control of a semiconductor process gas pipeline using the temperature control device is provided, comprising the following steps: Temperature detection steps: The temperature of the gas pipeline is detected by the temperature measuring unit and a temperature signal is generated.

[0035] Heating start-up step: When the temperature signal indicates that the temperature is lower than the first threshold, the control chip outputs a high-level signal through the first control port and the second control port, which turns on the first transistor Q1 and the second transistor Q2, driving the coils of the first relay K1 and the second relay K2 to be attracted, thereby forming a circuit of alternating current through the contacts of the first relay K1, the heating device, and the contacts of the second relay K2 to power the heating device.

[0036] Arc extinguishing and disconnection steps: S1: When the temperature signal indicates that the temperature has reached the first threshold, the control chip outputs a trigger signal to the thyristor drive optocoupler U1 through the fourth control port P1-14, turning on the bidirectional thyristor U9; S2: The control chip cancels the high-level signal of the second control port, turning off the second transistor Q2, de-energizing the coil of the second relay K2, and opening its contacts. At this time, the freewheeling diode D1 connected in parallel across the coil provides a current release path; S3: The load current is transferred from the contacts of the second relay K2 to the bidirectional thyristor U9 to continue flowing; S4: When the AC current naturally crosses zero, the bidirectional thyristor U9 turns off automatically, completing the arc-free disconnection, and the heating device stops heating.

[0037] Heating recovery step: When the temperature signal indicates that the temperature has dropped to the second threshold, the control chip outputs a high-level signal again through the second control port, which turns on the third transistor Q9, drives the coil of the second relay K2 to be energized, and its contacts close, restoring power supply to the heating device.

[0038] In some embodiments, after the arc extinguishing and disconnection step, a testing and adjustment step is further included: testing the on / off state and service life of the second relay K2 contact when a large current is passed; testing the discharge and follow current time when the bidirectional thyristor U9 is used to discharge current; and adjusting the on / off number setting of the second relay K2 contact according to the test results.

[0039] Testing the continuity of the second relay contacts involves checking whether the relay contacts can close and open normally when a large current flows, and whether there are any problems such as sticking or poor contact. This test can be performed by connecting a current sensor in series in the circuit to monitor the current changes in real time, thereby determining the continuity of the contacts. For testing the discharge current of the bidirectional thyristor, its discharge and freewheeling times are evaluated by measuring the current change curve after the thyristor is turned on. This process can be achieved using a voltage and current detection circuit, recording the thyristor's turn-off time at the zero-crossing point of the AC current, as well as the current stability during conduction.

[0040] The test results will serve as the basis for adjusting the relay contact switching frequency setting. The switching frequency setting refers to adjusting the maximum number of switching operations allowed by the relay per unit time based on the test results, in order to prevent contact wear or damage caused by frequent switching.

[0041] The above description is merely an explanation of some preferred embodiments of the present invention and the technical principles employed. Those skilled in the art should understand that the scope of the invention as described in the embodiments of the present invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above-described features with, but not limited to, technical features with similar functions disclosed in the embodiments of the present invention.

Claims

1. A temperature control device for a semiconductor process gas pipeline, applied to a temperature control system, the temperature control system comprising an externally connected heating device and a temperature measuring device, characterized in that, The temperature control device comprises: a temperature information receiving circuit electrically connected with the temperature measuring device and configured to receive temperature information sent by the temperature measuring device; a heating information output circuit electrically connected with the heating device and configured to control the on-off of power supply to the heating device; an arc control circuit electrically connected with the heating information output circuit and configured to provide a current freewheeling path when the heating information output circuit is disconnected from the load to eliminate arc; a control circuit electrically connected with the temperature information receiving circuit, the heating information output circuit and the arc control circuit, and configured to receive and process the temperature information; according to the processing result and a preset temperature threshold, output a control signal to the heating information output circuit to control the power supply state of the heating device; before the heating information output circuit is controlled to be disconnected, a trigger signal is first output to the arc control circuit to make thyristors therein conduct, realizing arc-free transfer and breaking of the heating loop current.

2. The apparatus of claim 1, wherein, The heating information output circuit comprises: a first driving unit and a second driving unit, input ends of the first driving unit and the second driving unit are connected with first and second control ends of the control circuit respectively, and output ends of the first driving unit and the second driving unit are electrically connected with the heating device respectively.

3. The apparatus of claim 2, wherein, The first driving unit comprises a first transistor, a first base resistor and a first relay, and the second driving unit comprises a second transistor, a second base resistor and a second relay; a base of the first transistor is connected to a first control port through the first base resistor, an emitter is grounded, and a collector is connected to a first end of a coil of the first relay; a base of the second transistor is connected to a second control port through the second base resistor, an emitter is grounded, and a collector is connected to a first end of a coil of the second relay; first and second freewheeling diodes are reversely connected in parallel across the first relay coil and the second relay respectively; one end of the first driving unit is electrically connected with one end of the second driving unit.

4. The apparatus of claim 3, wherein, The heating information output circuit further comprises a third driving unit; the third driving unit comprises a third transistor and a third base resistor; a base of the third transistor is connected to a third control port of the control circuit through the third base resistor, an emitter is grounded, and a collector is connected to the second transistor.

5. The apparatus of claim 1, wherein, The arc control circuit comprises a bidirectional thyristor and a photocoupler driving unit; the bidirectional thyristor is connected in parallel across the second relay, a gate thereof receives a driving signal of the photocoupler driving unit, and is used to freewheel power supply to the heating device and transfer arc generated when the second relay is disconnected.

6. The device according to claim 5, wherein an input end of the photocoupler driving unit is connected to a fourth control port of the control circuit, and an output end is connected to a gate of the bidirectional thyristor, and is used to trigger the bidirectional thyristor to conduct under the control of the control circuit.

7. The apparatus of claim 6, wherein, the photocoupler driving unit comprises a silicon-controlled driving photocoupler, a gate current-limiting resistor and a fourth transistor; The input side anode of the triac driving optocoupler is connected to the fourth control port of the control circuit in series, and the cathode is grounded. The first end of the output side of the triac driving optocoupler is connected to the gate of the bidirectional thyristor through the gate limiting resistor, and the second end of the output side is connected to the second main terminal of the bidirectional thyristor.

8. The apparatus of claim 7, wherein, The optocoupler driving unit further comprises a buffer resistor; The buffer resistor is connected between the gate of the bidirectional thyristor and the second main terminal thereof.

9. The device of claim 1, wherein, The heating information output circuit and the arc control circuit are arranged on a power board of the temperature control device; The control circuit and the temperature information receiving circuit are arranged on a main control board of the temperature control device; The main control board and the power board realize signal interaction through electrical connection.

10. A temperature control method for a semiconductor process gas line, comprising: The method comprises the following steps: S1: detecting the temperature of the gas pipeline by the temperature measuring unit and generating a temperature signal to be transmitted to the control unit; S2: the control unit receives and processes the temperature signal to determine the relationship between the current temperature and the first threshold value and the second threshold value; S3: if the temperature is determined to be lower than the first threshold value, the control unit outputs a control signal to make the contacts of the first relay and the second relay in the heating information output circuit closed, and the AC power supply supplies power to the heater; S4: if the temperature is determined to be equal to or greater than the first threshold value, the control unit first outputs a signal to trigger the bidirectional thyristor in the arc extinguishing circuit to conduct, and then outputs a control signal to disconnect the contacts of the second relay, so that the heating current is transferred to the bidirectional thyristor; S5: if the temperature is determined to be lower than the second threshold value, the control unit outputs a control signal to close the contacts of the second relay, the bidirectional thyristor is turned off at the subsequent AC zero crossing point, and the heater resumes power supply; S6: repeating steps S1-S5 to realize closed-loop control of the temperature of the gas pipeline and arc-free breaking of the relay.

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