An electric heating drive circuit system and control method

Abstract

This invention discloses an electric heating drive circuit system and control method, belonging to the field of electric heating control. The system includes a microcontroller unit (MCU), an isolation drive circuit, a MOSFET as the main switch, and a voltage detection feedback circuit. The MCU generates a drive signal, which, after electrical isolation by the isolation drive circuit, controls the switching on and off of the MOSFET, thereby controlling the main electric heating circuit. The voltage detection feedback circuit samples the voltage across the MOSFET to generate a status feedback signal, which is then isolated and fed back to the MCU, forming a closed-loop control. This invention replaces the mechanical contactor with a semiconductor MOSFET, completely eliminating arcing during switching and significantly improving switch life and system reliability. By integrating voltage detection and full-link isolation design, it achieves arc-free switching while retaining the status feedback function and ensuring electrical safety isolation between high and low voltage circuits.

Description

Technical Field

[0001] This invention belongs to the field of electric heating drive, specifically, it relates to an electric heating drive circuit system and control method. Background Technology

[0002] In applications involving long-term operation, such as rail vehicles and industrial equipment, electric heaters are critical temperature control components. Their conventional drive and control schemes typically rely on high-power DC contactors. The specific workflow is as follows: the control system issues a switching command, driving the contactor's coil to engage or disengage, thereby directly connecting or disconnecting the main circuit of the electric heater through its mechanical contacts. This main circuit typically carries high voltage and high current.

[0003] However, this traditional solution based on mechanical contactors has its inherent technical defects, especially under harsh operating conditions of high voltage and high current. Its electrical life is short and its reliability is insufficient. In severe cases, continuous electric arc or contact welding may cause contact adhesion failure, making it impossible for the heater to be turned off, causing equipment overheating or even safety accidents.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an electric heating drive circuit system.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: An electric heating drive circuit system includes: a microcontroller unit (MCU), an isolation drive circuit, a MOSFET IC201, and a voltage detection feedback circuit; The microcontroller unit (MCU) generates a drive signal based on the input voltage detection result. The input terminal of the isolation drive circuit is connected to the microcontroller unit (MCU) to receive drive signals, and its output terminal is connected to the control terminal of the MOSFET IC201. It is used to electrically isolate the drive signals and drive the MOSFET IC201 to turn on and off. The MOSFET IC201 is connected in series in the electric heating main circuit. The sampling terminal of the voltage detection feedback circuit is connected to both ends of the MOS transistor IC201 to form sampling point KMD1 and sampling point KMS1, which are used to sample the voltage when the MOS transistor IC201 is turned on or off, and generate a status feedback signal based on the sampled voltage. The output of the voltage detection feedback circuit is connected to the microcontroller unit (MCU) through an isolation element. The relay JDQ1 electrically isolates the status feedback signal and feeds it back to the MCU, forming a closed-loop control.

[0007] Preferably, the coil of the relay JDQ1 is driven by the status feedback signal output by the voltage detection feedback circuit, and the on / off state of its main contacts forms a status feedback signal, which is fed back to the microcontroller unit MCU.

[0008] Preferably, the isolation drive circuit includes an isolation optocoupler PQ1, a push-pull circuit, and an isolation drive optocoupler IC5; The input side of the isolation optocoupler PQ1 is connected to the drive signal output terminal of the microcontroller unit MCU through a current-limiting resistor R1. The output side of the isolation optocoupler PQ1 is connected to the input terminal of the push-pull circuit and outputs signal 1 to the push-pull circuit; The output of the push-pull circuit is connected to the input side of the isolation drive optocoupler IC5; The output side of the isolation drive optocoupler IC5 is connected to the control terminal of the MOS transistor IC201 through the drive resistor R10.

[0009] Preferably, the push-pull circuit includes a first transistor Q1 and a second transistor Q2; The base of the first transistor Q1 and the base of the second transistor Q2 are both connected to the output side of the isolation optocoupler PQ1; The emitter of the first transistor Q1 is connected to the emitter of the second transistor Q2 as the output node of the push-pull circuit, and outputs signal 2; The collector of the first transistor Q1 is connected to the power supply, and the collector of the second transistor Q2 is grounded.

[0010] Preferably, the voltage detection feedback circuit includes a differential sampling amplifier circuit, a comparator circuit, and an isolation feedback circuit; The input terminal of the differential sampling amplifier circuit is connected to the sampling points KMD1 and KMS1 of the MOS transistor IC201 through sampling resistors R12 and R13, for differential amplification of the sampled voltage. The first input terminal of the comparison circuit is connected to the output terminal of the differential sampling amplifier circuit, and the second input terminal is connected to a preset comparison voltage, which is used to compare the amplified sampling voltage with the comparison voltage and output a comparison result signal. The input terminal of the isolation feedback circuit is connected to the output terminal of the comparison circuit, and is used to output the comparison result signal after electrical isolation to form a status feedback signal.

[0011] Preferably, the differential sampling amplifier circuit includes operational amplifier IC3; The input terminal of the operational amplifier IC3 is connected to the sampling points KMD1 and KMS1 of the MOS transistor IC201 through sampling resistors R12 and R13, and its output terminal is connected to the first input terminal of the comparator circuit.

[0012] Preferably, the comparison circuit includes comparator IC4; The first input terminal of the comparison circuit is the negative input terminal of comparator IC4, which is connected to the output terminal of the differential sampling amplifier circuit. The second input terminal of the comparison circuit is the positive input terminal of comparator IC4, which is connected to a preset comparison voltage. This is used to compare the amplified sampling voltage with the comparison voltage and output the comparison result signal.

[0013] Preferably, the isolation feedback circuit includes an isolation optocoupler PQ2 and a fourth transistor Q4; The output terminal of the comparator circuit outputs a comparison result signal to the base of the third transistor Q3, and the collector of the third transistor Q3 is connected to the anode of the light-emitting diode on the input side of the isolation optocoupler PQ2. The collector of the transistor on the output side of the isolation optocoupler PQ2 is connected to the power supply through a current-limiting resistor R27; The emitter of the output transistor of the isolation optocoupler PQ2 is connected to the base of the fourth transistor Q4 through the driving resistor R29. The collector of the fourth transistor Q4 is connected to one end of the coil of the relay JDQ1, the other end of the coil of the relay JDQ1 is connected to the power supply, and the emitter of the fourth transistor Q4 is grounded.

[0014] Preferably, the electric heating main circuit is further provided with a fuse and / or a varistor.

[0015] This invention also provides a method for controlling an electric heating drive circuit, applied to a circuit system including a microcontroller unit (MCU), a drive circuit, a MOSFET (IC201), and a voltage detection feedback circuit, the method comprising: The microcontroller unit (MCU) outputs a drive signal based on the input voltage detection result. After electrical isolation, the drive signal controls the MOS transistor IC201 to turn on or off, thereby controlling the on / off state of the electric heating main circuit. The voltage detection feedback circuit samples the voltage across the MOS transistor IC201 and generates a feedback signal based on the sampling result. The feedback signal is transmitted to the microcontroller unit (MCU) after electrical isolation, forming a drive control closed loop.

[0016] By adopting the above technical solution, the electric heating drive circuit system and control method provided by the present invention have the following beneficial effects compared with the prior art.

[0017] By replacing the traditional mechanical contactor with a semiconductor MOSFET IC201 as the main circuit switch, the contact arcing phenomenon during high current switching is fundamentally eliminated, thereby greatly improving the electrical life of the switching element and the system reliability. It integrates voltage detection feedback circuit and isolation design, and can maintain the same state feedback function as the traditional contactor scheme while achieving arc-free switching, forming a reliable closed-loop control and ensuring electrical safety isolation between the high-voltage part and the low-voltage control part.

[0018] By limiting relay JDQ1 to be driven by a feedback signal and serving as the carrier of the feedback signal, the state of the main contacts of relay JDQ1 provides an intuitive and reliable hardware status feedback signal to the microcontroller unit (MCU).

[0019] An isolated drive circuit is constructed by using an isolation optocoupler PQ1, a push-pull circuit, and a drive optocoupler IC5. This multi-level isolation ensures complete electrical isolation between high-voltage and low-voltage circuits on the drive signal transmission path, enhancing anti-interference capability and system safety. The push-pull circuit provides power amplification and shaping of the drive signal, ensuring that a stable and sufficiently powerful control signal can be provided to the gate of the MOSFET, guaranteeing that the MOSFET can be turned on and off quickly and reliably. Attached Figure Description

[0020] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the application framework of the present invention; Figure 2 This is a schematic diagram of the isolation drive circuit of the present invention; Figure 3 This is a schematic diagram of the voltage detection feedback circuit of the present invention; Figure 4 This is a schematic diagram of the isolated power supply circuit of the present invention.

[0021] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0023] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] like Figures 1 to 4 As shown, the present invention provides an electric heating drive circuit system, including: a microcontroller unit (MCU), an isolation drive circuit, a MOSFET IC201, and a voltage detection feedback circuit; The microcontroller unit (MCU) generates a drive signal based on the input voltage detection result. The input terminal of the isolation drive circuit is connected to the microcontroller unit (MCU) to receive drive signals, and its output terminal is connected to the control terminal of the MOSFET IC201. It is used to electrically isolate the drive signals and drive the MOSFET IC201 to turn on and off. The MOSFET IC201 is connected in series in the electric heating main circuit. The sampling terminal of the voltage detection feedback circuit is connected to both ends of the MOS transistor IC201 to form sampling point KMD1 and sampling point KMS1, which are used to sample the voltage when the MOS transistor IC201 is turned on or off, and generate a status feedback signal based on the sampled voltage. The output of the voltage detection feedback circuit is connected to the microcontroller unit (MCU) through an isolation element. The relay JDQ1 electrically isolates the status feedback signal and feeds it back to the MCU, forming a closed-loop control.

[0027] By replacing the traditional mechanical contactor with a semiconductor MOSFET IC201 as the main circuit switch, the contact arcing phenomenon during high current switching is fundamentally eliminated, thereby greatly improving the electrical life of the switching element and the system reliability. It integrates voltage detection feedback circuit and isolation design, and can maintain the same state feedback function as the traditional contactor scheme while achieving arc-free switching, forming a reliable closed-loop control and ensuring electrical safety isolation between the high-voltage part and the low-voltage control part.

[0028] Furthermore, the coil of the relay JDQ1 is driven by the status feedback signal output by the voltage detection feedback circuit, and the on / off state of its main contacts forms a status feedback signal, which is fed back to the microcontroller unit MCU.

[0029] By limiting relay JDQ1 to be driven by a feedback signal and serving as the carrier of the feedback signal, the state of the main contacts of relay JDQ1 provides an intuitive and reliable hardware status feedback signal to the microcontroller unit (MCU).

[0030] Preferably, the isolation drive circuit includes an isolation optocoupler PQ1, a push-pull circuit, and an isolation drive optocoupler IC5; The input side of the isolation optocoupler PQ1 is connected to the drive signal output terminal of the microcontroller unit MCU through a current-limiting resistor R1. The output side of the isolation optocoupler PQ1 is connected to the input terminal of the push-pull circuit and outputs signal 1 to the push-pull circuit; The output of the push-pull circuit is connected to the input side of the isolation drive optocoupler IC5; The output side of the isolation drive optocoupler IC5 is connected to the control terminal of the MOS transistor IC201 through the drive resistor R10.

[0031] An isolated drive circuit is constructed by using an isolation optocoupler PQ1, a push-pull circuit, and a drive optocoupler IC5. This multi-level isolation ensures complete electrical isolation between high-voltage and low-voltage circuits on the drive signal transmission path, enhancing anti-interference capability and system safety. The push-pull circuit provides power amplification and shaping of the drive signal, ensuring that a stable and sufficiently powerful control signal can be provided to the gate of the MOSFET, guaranteeing that the MOSFET can be turned on and off quickly and reliably.

[0032] Preferably, the push-pull circuit includes a first transistor Q1 and a second transistor Q2; The base of the first transistor Q1 and the base of the second transistor Q2 are both connected to the output side of the isolation optocoupler PQ1; The emitter of the first transistor Q1 is connected to the emitter of the second transistor Q2 as the output node of the push-pull circuit, and outputs signal 2; The collector of the first transistor Q1 is connected to the power supply, and the collector of the second transistor Q2 is grounded.

[0033] The push-pull circuit effectively improves the driving capability and response speed of the output signal. Whether the output is high (Q1 is on) or low (Q2 is on), it provides a low-impedance output path, thereby ensuring that the signal (signal 2) provided to the subsequent isolated driver optocoupler (IC5) has a steep edge and strong load-carrying capacity, further optimizing the switching performance of the MOSFET.

[0034] like Figure 2 As shown, R1, R3, and R7 are current-limiting resistors; D1 is an optocoupler clamping diode; R2 and R9 are optocoupler clamping resistors; PQ1 is an isolation optocoupler; R5 is a transistor drive resistor; R4 and R6 are transistor pull-down resistors; R8 is an output current control resistor; R11 is a pull-down resistor for the MOSFET IC201; D2 and D3 are Zener diodes; IC5 is an isolation drive optocoupler; R10 is a drive resistor; and C1, C2, C3, C4, C5, and C6 are filter capacitors.

[0035] The microcontroller unit (MCU) sends a drive signal. When the + drive signal is greater than the - drive signal, the light-emitting side of the isolation optocoupler PQ1 is turned on, and the output transistor side is turned on. Signal 1 outputs a high level, driving the push-pull circuit composed of the first transistor Q1 and the second transistor Q2. The first transistor Q1 turns on, and Signal 2 outputs a high level. The anode of the isolation drive optocoupler IC5 is pulled high, and Vo outputs a high level, supplying power to the gate of the MOSFET IC201, thus turning on the MOSFET and controlling the conduction of the electric heating circuit, starting the electric heating operation. The isolation drive optocoupler achieves isolation between the drive signal and the MOSFET.

[0036] Similarly, when the MCU does not output a drive signal, the light-emitting side of the isolation optocoupler PQ1 cannot be turned on, signal 1 outputs a low level, the second transistor Q2 is turned on, signal 2 outputs a low level, the isolation drive optocoupler IC5 outputs a low level, and the MOSFET IC201 is turned off.

[0037] The voltage detection feedback circuit includes a differential sampling amplifier circuit, a comparator circuit, and an isolation feedback circuit; The input terminal of the differential sampling amplifier circuit is connected to the sampling points KMD1 and KMS1 of the MOS transistor IC201 through sampling resistors R12 and R13, for differential amplification of the sampled voltage. The first input terminal of the comparison circuit is connected to the output terminal of the differential sampling amplifier circuit, and the second input terminal is connected to a preset comparison voltage, which is used to compare the amplified sampling voltage with the comparison voltage and output a comparison result signal. The input terminal of the isolation feedback circuit is connected to the output terminal of the comparison circuit, and is used to output the comparison result signal after electrical isolation to form a status feedback signal.

[0038] The differential sampling amplifier circuit includes an operational amplifier IC3; the input terminal of the operational amplifier IC3 is connected to the sampling points KMD1 and KMS1 of the MOS transistor IC201 through sampling resistors R12 and R13, and its output terminal is connected to the first input terminal of the comparator circuit.

[0039] The comparison circuit includes comparator IC4; The first input terminal of the comparison circuit is the negative input terminal of comparator IC4, which is connected to the output terminal of the differential sampling amplifier circuit. The second input terminal of the comparison circuit is the positive input terminal of comparator IC4, which is connected to a preset comparison voltage. This is used to compare the amplified sampling voltage with the comparison voltage and output the comparison result signal.

[0040] The non-inverting input terminal of the comparator IC4 is provided with an operational amplifier peripheral resistor R21. One end of the operational amplifier peripheral resistor R21 is connected to the comparator IC4, and the other end is connected to both a pull-up resistor R22 and a pull-down resistor R23. Pull-up resistor R22 is connected to the power supply, and pull-down resistor R23 is grounded, forming a comparison voltage between the op-amp's external resistor R21, pull-up resistor R22, and pull-down resistor R23.

[0041] The isolation feedback circuit includes an isolation optocoupler PQ2 and a fourth transistor Q4; The output terminal of the comparator circuit outputs a comparison result signal to the base of the third transistor Q3, and the collector of the third transistor Q3 is connected to the anode of the light-emitting diode on the input side of the isolation optocoupler PQ2. The collector of the transistor on the output side of the isolation optocoupler PQ2 is connected to the power supply through a current-limiting resistor R27; The emitter of the output transistor of the isolation optocoupler PQ2 is connected to the base of the fourth transistor Q4 through the driving resistor R29. The collector of the fourth transistor Q4 is connected to one end of the coil of the relay JDQ1, the other end of the coil of the relay JDQ1 is connected to the power supply, and the emitter of the fourth transistor Q4 is grounded.

[0042] like Figure 3As shown, R12 and R13 are sampling resistors, R15 is the first differential resistor at the negative input of operational amplifier IC3, R14 is the first differential resistor at the positive input of operational amplifier IC3, R17 is the feedback resistor of operational amplifier IC3, R22 is a pull-up resistor, R16, R23, R25, and R30 are pull-down resistors, R26, R27, and R28 are current-limiting resistors, R19, R20, and R21 are external resistors of the operational amplifier, R18, R24, and R29 are drive resistors, IC3 is an operational amplifier, IC4 is a comparator, JDQ1 is a relay, D4 is a freewheeling diode for the relay, and C7, C8, C9, C10, C11, C12, C13, and C14 are filter capacitors.

[0043] The resistance values ​​of R22 and R23 can be adjusted according to the actual application conditions to set a suitable comparison voltage.

[0044] When MOSFET IC201 is turned on, the voltage at point KMD1 is pulled low for voltage sampling. Operational amplifier IC3 performs differential amplification. By setting the values ​​of R14, R15, R16, and R17, the output of operational amplifier IC3 can be made into a proportional value. The voltage at sampling point 1 is output and passes through comparator IC4. At this time, sampling point 1 is less than the comparison voltage, so comparator IC4 outputs a high level, turning on the third transistor Q3, the output transistor of the isolation optocoupler PQ2, and the fourth transistor Q4. The relay JDQ1 is energized, and the signal is fed back to the microcontroller unit (MCU) through the external control board, realizing a feedback closed loop.

[0045] Similarly, when MOSFET IC201 is turned off, the voltage at point KMD1 is the high voltage across MOSFET IC201. After sampling by the sampling resistor, the operational amplifier IC3 performs differential amplification and outputs the voltage at sampling point 1. At this time, sampling point 1 is greater than the comparison voltage, the comparator IC4 outputs a low level, the third transistor Q3 is turned off, the output transistor of the isolation optocoupler PQ2 is turned off, the fourth transistor Q4 is turned off, and the relay JDQ1 is not energized. The signal is fed back to the microcontroller unit MCU through the external control board to realize the feedback closed loop.

[0046] Preferably, the main electric heating circuit is further equipped with a fuse and / or a varistor. This provides an additional layer of hardware protection for the entire electric heating drive system. The fuse can quickly melt and disconnect the main power supply in the event of an overcurrent or short circuit, while the varistor can absorb surge voltages in the power grid, preventing overvoltage from damaging the MOSFET and other sensitive components. The addition of these protective devices significantly improves the robustness and safety of the system under abnormal operating conditions. Simultaneously, it makes the cost of the drive circuit system of this invention lower than that of a DC contactor with equivalent voltage and current.

[0047] like Figure 4As shown, L4 is a fuse, D5 is a reverse protection diode, IC1 and IC2 are the isolation power supply module, L1, L2, and L3 are common-mode inductors, D6 is a Zener diode, and C15, C16, C17, C18, C19, C20, C21, and C22 are filter capacitors. Vin is the input DC power, which is filtered by the capacitors. The isolation power supply module steps down the voltage and provides isolation, ultimately outputting an isolated power supply suitable for driving signal circuits and voltage detection feedback circuits. (This isolation power supply can also use other common isolation power supplies on the market, as long as they meet the functional requirements; it is not the only solution.) This embodiment also provides an electric heating drive circuit control method, applied to a circuit system including a microcontroller unit (MCU), a drive circuit, a MOSFET (IC201), and a voltage detection feedback circuit. The method includes: The microcontroller unit (MCU) outputs a drive signal based on the input voltage detection result. After electrical isolation, the drive signal controls the MOS transistor IC201 to turn on or off, thereby controlling the on / off state of the electric heating main circuit. The voltage detection feedback circuit samples the voltage across the MOS transistor IC201 and generates a feedback signal based on the sampling result. The feedback signal is transmitted to the microcontroller unit (MCU) after electrical isolation, forming a drive control closed loop.

[0048] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An electric heating drive circuit system, characterized in that, include: Microcontroller unit (MCU), isolation drive circuit, MOSFET IC201, and voltage detection feedback circuit; The microcontroller unit (MCU) generates a drive signal based on the input voltage detection result. The input terminal of the isolation drive circuit is connected to the microcontroller unit (MCU) to receive drive signals, and its output terminal is connected to the control terminal of the MOSFET IC201. It is used to electrically isolate the drive signals and drive the MOSFET IC201 to turn on and off. The MOSFET IC201 is connected in series in the electric heating main circuit. The sampling terminal of the voltage detection feedback circuit is connected to both ends of the MOS transistor IC201 to form sampling point KMD1 and sampling point KMS1, which are used to sample the voltage when the MOS transistor IC201 is turned on or off, and generate a status feedback signal based on the sampled voltage. The output of the voltage detection feedback circuit is connected to the microcontroller unit (MCU) through an isolation element. The relay JDQ1 electrically isolates the status feedback signal and feeds it back to the MCU, forming a closed-loop control.

2. The electric heating drive circuit system according to claim 1, characterized in that, The coil of the relay JDQ1 is driven by the status feedback signal output by the voltage detection feedback circuit, and the on / off state of its main contacts forms a status feedback signal, which is fed back to the microcontroller unit MCU.

3. An electric heating drive circuit system according to claim 1 or 2, characterized in that, The isolation drive circuit includes an isolation optocoupler PQ1, a push-pull circuit, and an isolation drive optocoupler IC5. The input side of the isolation optocoupler PQ1 is connected to the drive signal output terminal of the microcontroller unit MCU through a current-limiting resistor R1. The output side of the isolation optocoupler PQ1 is connected to the input terminal of the push-pull circuit and outputs signal 1 to the push-pull circuit; The output of the push-pull circuit is connected to the input side of the isolation drive optocoupler IC5; The output side of the isolation drive optocoupler IC5 is connected to the control terminal of the MOS transistor IC201 through the drive resistor R10.

4. The electric heating drive circuit system according to claim 3, characterized in that, The push-pull circuit includes a first transistor Q1 and a second transistor Q2; The base of the first transistor Q1 and the base of the second transistor Q2 are both connected to the output side of the isolation optocoupler PQ1; The emitter of the first transistor Q1 is connected to the emitter of the second transistor Q2 as the output node of the push-pull circuit, and outputs signal 2; The collector of the first transistor Q1 is connected to the power supply, and the collector of the second transistor Q2 is grounded.

5. An electric heating drive circuit system according to claim 1 or 2, characterized in that, The voltage detection feedback circuit includes a differential sampling amplifier circuit, a comparator circuit, and an isolation feedback circuit; The input terminal of the differential sampling amplifier circuit is connected to the sampling points KMD1 and KMS1 of the MOS transistor IC201 through sampling resistors R12 and R13, for differential amplification of the sampled voltage. The first input terminal of the comparison circuit is connected to the output terminal of the differential sampling amplifier circuit, and the second input terminal is connected to a preset comparison voltage, which is used to compare the amplified sampling voltage with the comparison voltage and output a comparison result signal. The input terminal of the isolation feedback circuit is connected to the output terminal of the comparison circuit, and is used to output the comparison result signal after electrical isolation to form a status feedback signal.

6. The electric heating drive circuit system according to claim 5, characterized in that, The differential sampling amplifier circuit includes operational amplifier IC3; The input terminal of the operational amplifier IC3 is connected to the sampling points KMD1 and KMS1 of the MOS transistor IC201 through sampling resistors R12 and R13, and its output terminal is connected to the first input terminal of the comparator circuit.

7. The electric heating drive circuit system according to claim 6, characterized in that, The comparison circuit includes comparator IC4; The first input terminal of the comparison circuit is the negative input terminal of comparator IC4, which is connected to the output terminal of the differential sampling amplifier circuit. The second input terminal of the comparison circuit is the positive input terminal of comparator IC4, which is connected to a preset comparison voltage. This is used to compare the amplified sampling voltage with the comparison voltage and output the comparison result signal.

8. The electric heating drive circuit system according to claim 5, characterized in that, The isolation feedback circuit includes an isolation optocoupler PQ2 and a fourth transistor Q4; The output terminal of the comparator circuit outputs a comparison result signal to the base of the third transistor Q3, and the collector of the third transistor Q3 is connected to the anode of the light-emitting diode on the input side of the isolation optocoupler PQ2. The collector of the transistor on the output side of the isolation optocoupler PQ2 is connected to the power supply through a current-limiting resistor R27; The emitter of the output transistor of the isolation optocoupler PQ2 is connected to the base of the fourth transistor Q4 through the driving resistor R29. The collector of the fourth transistor Q4 is connected to one end of the coil of the relay JDQ1, the other end of the coil of the relay JDQ1 is connected to the power supply, and the emitter of the fourth transistor Q4 is grounded.

9. An electric heating drive circuit system according to claim 2, characterized in that, The electric heating main circuit is also equipped with a fuse and / or a varistor.

10. A method for controlling an electric heating drive circuit, applied to a circuit system including a microcontroller unit (MCU), a drive circuit, a MOSFET (IC201), and a voltage detection feedback circuit, characterized in that, The method includes: The microcontroller unit (MCU) outputs a drive signal based on the input voltage detection result. After electrical isolation, the drive signal controls the MOS transistor IC201 to turn on or off, thereby controlling the on / off state of the electric heating main circuit. The voltage detection feedback circuit samples the voltage across the MOS transistor IC201 and generates a feedback signal based on the sampling result. The feedback signal is transmitted to the microcontroller unit (MCU) after electrical isolation, forming a drive control closed loop.

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