An AC heating control and feedback circuit based on optocoupler and thyristor

Abstract

The present invention belongs to the field of electronic circuit technology and relates to an AC heating control and feedback circuit based on an optocoupler and a thyristor. The advantage of this circuit is that it uses an optocoupler and a thyristor to control the on and off of AC power, and is designed with a detection feedback circuit. This circuit utilizes the characteristics of the thyristor contactless switch, high reliability, and small current control of large current to perform real-time detection of the heating control circuit, providing a basis for determining the on and off status of the heater. It has the characteristics of a simple, stable, highly reliable circuit structure, low power consumption, and strong anti-interference capabilities. This circuit solves the circuit design problem of low reliability of traditional electromagnetic relays and difficulty in AC detection and feedback when the external power supply is AC power, which existed during the product development process.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic circuits and relates to an alternating current heating control and feedback circuit based on an optocoupler and a thyristor. Background Art

[0002] In traditional heating control circuits, due to the high heating power, electromagnetic relays are often used to control high currents with low currents. However, because electromagnetic relays use electromagnetic effects to control the opening and closing of mechanical contacts, they can suffer from contact sticking failure modes. Furthermore, when an external power supply system provides single-phase AC power as the heating power source, detecting and providing feedback on the AC power is difficult. This circuit uses optocouplers and thyristors to control the AC power on and off, and incorporates a detection and feedback circuit. This circuit utilizes the thyristor's contactless switching, high reliability, and ability to control high currents with low currents. This circuit provides real-time monitoring of the heating control circuit, providing a basis for determining the heater's on / off status. It features a simple, stable, reliable, low-power, and strong anti-interference capabilities. Summary of the Invention

[0003] The purpose of the present invention is to use an AC heating control and feedback circuit based on an optocoupler and a thyristor to solve the circuit design problems of low reliability of traditional electromagnetic relays and difficulty in AC detection and feedback when AC power is supplied externally during product development.

[0004] Technical Solution

[0005] An AC heating control and feedback circuit based on optocoupler and thyristor. The optocoupler N1 trigger terminal is controlled by the DSP or single-chip microcomputer I / O port. When the heating control signal is high, the optocoupler N1 trigger terminal current I>I 触发 When the heating control signal is low, T1*(12VAC) and T2* are cut off, and 12VAC flows through the back-end feedback circuit. After half-wave rectification by the rectifier diode D2, it is connected in series with the resistor R5, the light-emitting diode of the optocoupler N2, and the heater to form a trigger current. When the current I>I 触发 When , the output of the optocoupler is turned on, and after filtering by capacitors C1 and C2, the heating feedback signal is a stable low level.

[0006] The trigger terminal current of the optocoupler N1 is determined by the heating control signal voltage, the resistance of the current limiting resistor R1, and the voltage drop of the light emitting diode of the optocoupler N1. When the trigger terminal current I>I 触发 When , the optocoupler output terminal can be turned on and can be selected according to requirements.

[0007] The G-level trigger current of the thyristor V1 is determined by the AC voltage, the resistance of the current-limiting resistors R2 and R3, and the conduction voltage drop at the output of the optocoupler N1. When the trigger current I flowing through the G-level is greater than I 触发 When , T1* and T2* are connected, which can be selected according to requirements.

[0008] The trigger current of the optocoupler N2 is determined by the AC voltage, the rectifier diode, the resistance of the current limiting circuit R4 and R5, and the voltage drop of the light-emitting diode of the optocoupler N2. When the current I flowing through the trigger terminal of the optocoupler N2 is greater than I 触发 When , T1* and T2* are connected, which can be selected according to requirements.

[0009] The heating feedback signal voltage is determined by the pull-up voltage 5V, the current-limiting resistor R6, and the on-state voltage drop at the output of the optocoupler N2, and can be selected according to requirements.

[0010] The filter capacitors C1 and C2 are half-waves after sine wave rectification because the trigger end of the optocoupler N2 is a half-wave, and the optocoupler N2 outputs a square wave under the condition of pulling up a 5V voltage. By adding the filter capacitors C1 and C2, a relatively stable low level is formed when the trigger end of the optocoupler N2 is turned on.

[0011] During actual use, the on-state voltage drop at the output of the thyristor V1 and the optocouplers N1 and N2 and the trigger current conditions under extreme temperature environments should be considered to ensure that the current limiting resistor selection and circuit design can still meet the trigger conditions under high and low temperature extreme environments.

[0012] Among the switching elements, the optocoupler N1 is GH3062, the thyristor V1 is JTKS25-6, the rectifier diode D1 is 2CZ103MZ01, the optocoupler N2 is GH302-1, and the filter capacitors C1 and C2 are 10uF and 0.01uF respectively.

[0013] Technical Effects

[0014] This circuit's advantages lie in its use of optocouplers and thyristors to control AC current on and off. It also incorporates a detection and feedback circuit. This circuit leverages the thyristor's contactless switching characteristics, high reliability, and ability to control large currents with small currents. This circuit provides real-time monitoring of the heating control circuit, providing a basis for determining the heater's on / off status. It boasts a simple, stable, reliable circuit structure, low power consumption, and strong anti-interference capabilities. This circuit overcomes the circuit design issues encountered during product development: the low reliability of traditional electromagnetic relays and the difficulty of AC current detection and feedback when powered by external AC. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a circuit diagram of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the following embodiments. The following are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] This AC heating control and feedback circuit, based on optocouplers and thyristors, is primarily used when the external heating voltage is AC. Using optocouplers and thyristors, it controls the on / off state of the AC power. Through rectification, optical isolation, and filtering, it provides real-time monitoring and feedback on the on / off status of the internal heater, thereby determining the effectiveness of the heating control. It features a simple, stable, highly reliable circuit structure, low power consumption, and strong anti-interference capabilities.

[0018] In the circuit for controlling the on-off of AC power by the optocoupler and thyristor, the trigger end of the optocoupler N1 is controlled by the DSP or the I / O port of the single-chip microcomputer. When the heating control signal is at a high level, the current I>I 触发 , the output end of the optocoupler is turned on, the G-level trigger current of the thyristor reaches the trigger condition, T1* (12VAC) and T2* are turned on, and the heater is controlled to start heating, achieving the purpose of small current controlling large current and contactless switch control.

[0019] In the detection feedback circuit for rectifying, photoelectrically isolating, and filtering the AC power, the 12VAC AC power is half-wave rectified by the rectifier diode D1 and connected in series with the resistor R5, the optocoupler N2 light-emitting diode, and the heater to form a trigger current. When the current I>I 触发 When , the output of the optocoupler is turned on, and after filtering by capacitors C1 and C2, the heater check signal is a stable low level.

[0020] In the heating feedback circuit, when the heating control signal of the DSP or single-chip microcomputer I / O port is at a high level, the thyristor T1 and T2 levels are connected, short-circuiting the back-end feedback circuit. At this time, the heating feedback signal should be a high level with a 5V pull-up. On the contrary, when the thyristor T1 and T2 levels are not connected, the AC current passes through the feedback circuit loop. At this time, the heating feedback signal should be a low level. If it does not match, it indicates a heater failure.

[0021] Among the switch elements, the optocoupler N1 is selected as GH3062, and the thyristor V1 is selected as JTKS25-6.

[0022] The rectifier diode D1 is selected as 2CZ103MZ01, and the optocoupler N2 is selected as GH302-1.

[0023] The capacitance values ​​of the filter capacitors C1 and C2 are selected to be 10uF and 0.01uF.

[0024] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical terms and scientific terms) have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have a meaning consistent with that in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless defined as herein. The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An AC heating control and feedback circuit based on optocoupler and thyristor, characterized in that: The I / 0 port of the control chip is connected in series with a current-limiting resistor R1 and then connected to the input pin 1 of the optocoupler N1. The input pin 2 of the optocoupler N1 is connected to the ground. The output pin 3 of the optocoupler N1 is connected in series with a current-limiting resistor R2 and then connected to the main terminal T1* of the thyristor V1. The output pin 4 of the optocoupler N1 is connected to the G level of the thyristor V1. The output pin 4 of the optocoupler N1 is connected in series with a current-limiting resistor R3 and then connected to the main terminal T2* of the thyristor V1. The AC end of the 12VAC single-phase AC power is connected to the main terminal T1* of the thyristor V1. The AC ground end of the 12VAC single-phase AC power is connected in series with a heater. Then connect it to the main terminal T2* of the thyristor V1; the main terminal T1* of the thyristor V1 is connected to the positive electrode of the rectifier diode D1, the negative electrode of the rectifier diode D1 is connected in series with the current limiting resistor R4 and then connected to the input terminal 1 pin of the optocoupler N2, and the input terminal 2 pin of the optocoupler N2 is connected to the 12VAC AC ground through the heater; the current limiting resistor R5 and the diode D2 are connected in parallel between the input terminals 1 and 2 of the optocoupler N2, where the positive electrode of the diode D2 is connected to the input terminal 2 pin of the optocoupler N2, and the negative electrode of the diode D2 is connected to the input terminal 1 pin of the optocoupler N2; the current limiting resistor R5 and the diode D2 are connected in parallel between the output terminals 3 and 4 of the optocoupler N2. Capacitor C1 and capacitor C2, optocoupler N2 output terminal 3 pin is connected to 5V power supply through pull-up resistor R6, optocoupler N2 output terminal 4 pin is grounded, optocoupler N2 output terminal 3 pin is connected to the I / 0 port of the control chip as the heating feedback signal; optocoupler N1 trigger terminal is controlled by DSP or single-chip microcomputer I / O port, when the heating control signal is high level, optocoupler N1 trigger terminal current I>I trigger, optocoupler N1 output terminal is turned on, G level trigger current of thyristor V1 reaches the trigger condition, T1* or 12VAC and T2* are turned on, the heater starts heating, and at the same time 12VAC short-circuits the back-end feedback circuit through T1* and T2*. At this time, the heating feedback signal should be a high level with a 5V pull-up. When the heating control signal is low, T1* or 12VAC and T2* are cut off, and 12VAC flows through the back-end feedback circuit. After half-wave rectification by the rectifier diode D2, it is connected in series with the resistor R5, the optocoupler N2 light-emitting diode, and the heater to form a trigger current. When the current I>I trigger at the trigger end of the optocoupler N2, the optocoupler output is turned on. After filtering by the capacitors C1 and C2, the heating feedback signal is a stable low level.

2. The AC heating control and feedback circuit based on optocoupler and thyristor according to claim 1, characterized in that: The trigger terminal current of the optocoupler N1 is determined by the heating control signal voltage, the resistance of the current limiting resistor R1, and the voltage drop of the light-emitting diode of the optocoupler N1. When the trigger terminal current I>I trigger of the optocoupler N1, the output terminal of the optocoupler N1 is turned on.

3. The AC heating control and feedback circuit based on optocoupler and thyristor according to claim 1, characterized in that: The G-level trigger current of the thyristor V1 is determined by the AC voltage, the current-limiting resistor R2, the resistance of the current-limiting resistor R3, and the conduction voltage drop at the output end of the optocoupler N1. When the trigger current I flowing through the G-level is greater than I trigger, T1* and T2* are turned on.

4. The AC heating control and feedback circuit based on optocoupler and thyristor according to claim 1, characterized in that: The trigger current of the optocoupler N2 is determined by the AC voltage, the rectifier diode D1, the current limiting resistor R4, the resistance of the current limiting resistor R5, and the voltage drop of the light-emitting diode of the optocoupler N2. When the current I flowing through the trigger terminal of the optocoupler N2 is greater than I trigger, T1* and T2* are turned on.

5. The AC heating control and feedback circuit based on optocoupler and thyristor according to claim 1, characterized in that: The heating feedback signal voltage is determined by the pull-up voltage 5V, the current limiting resistor R6, and the on-state voltage drop of the output end of the optocoupler N2.

6. The AC heating control and feedback circuit based on optocoupler and thyristor according to claim 1, characterized in that: The capacitors C1 and C2 are half-waves after sine wave rectification because the trigger end of the optocoupler N2 is pulled up to 5V and output as square waves. By adding the capacitors C1 and C2, a relatively stable low level is formed when the trigger end of the optocoupler N2 is turned on.

7. The AC heating control and feedback circuit based on optocoupler and thyristor according to claim 1, characterized in that: During actual use, the on-state voltage drop at the output of thyristor V1 and optocoupler N1 and N2 and the trigger current conditions under extreme temperature environments should be considered to ensure that the current limiting resistor selection and circuit design still meet the trigger conditions under high and low temperature extreme environments.

8. The AC heating control and feedback circuit based on optocoupler and thyristor according to claim 1, characterized in that: The optocoupler N1 is selected as GH3062, the thyristor V1 is selected as JTKS25-6; the rectifier diode D1 is selected as 2CZ103MZ01, the optocoupler N2 is selected as GH3021; ​​the capacitance values ​​of the capacitors C1 and C2 are selected as 10uF and 0.01uF respectively.

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