A power control circuit and electronic equipment based on thyristor

Abstract

The utility model discloses a power control circuit and electronic equipment based on thyristor, wherein the circuit includes a single chip microcomputer, a heating wire, a thyristor, a voltage and current processing module, a zero-crossing detection module and a voltage detection module, wherein: the voltage and current processing module, the thyristor, the heating wire and the zero-crossing detection module are all connected to an AC input power supply, the single chip microcomputer is connected to an optical coupling module, the voltage and current processing module, the heating wire, the optical coupling module and the zero-crossing detection module are all connected to the thyristor, the voltage and current processing module is connected to the optical coupling module, and the zero-crossing detection module, the voltage detection module and the voltage and current processing module are respectively connected to the single chip microcomputer. The utility model combines the single chip microcomputer and the zero-crossing detection, and uses the ratio of the number of times the thyristor is turned on and off at zero crossing to adjust the output, so that the output power is maintained in a relatively constant range, and the sudden increase of the heating wire voltage is avoided to cause a malfunction to the equipment.

Description

Technical Field

[0001] The utility model relates to the technical field of power control circuits, in particular to a power control circuit and electronic equipment based on thyristors. Background Art

[0002] Thyristor, also known as thyristor, is the abbreviation of thyristor. It is a high-power switching semiconductor device with the advantages of small size, high efficiency and long life. It is widely used in industrial products such as home appliances. In automatic control systems, thyristors can be used as high-power driving devices to control high-power devices with low-power controls. In addition, thyristors are also widely used in AC and DC motor speed control systems, power control systems and follow-up systems.

[0003] When current flows in the circuit, the heating wire will generate heat. When the voltage suddenly rises, since the resistance of the heating wire is relatively fixed, the current on the heating wire increases, causing the heat of the heating wire to rise sharply. The heat increases sharply in an instant, causing the temperature of the electrical equipment to increase sharply. If the output power cannot be controlled in time, and the output power changes too much, it will damage some electronic components, making it difficult for the electrical equipment to maintain a long service life.

[0004] At present, the control scheme for thyristors usually adopts a voltage zero-crossing detection module. In an AC circuit connected to an inductive load, the current zero-crossing position is estimated by using the power supply voltage waveform actually detected by the voltage zero-crossing detection module, and the conduction angle of the thyristor is adjusted according to the estimated current zero-crossing position to control the conduction of the thyristor. Since inductive loads (such as AC motors) will produce different degrees of current hysteresis, there are irregular changes in the voltage and current phase difference, resulting in a large error between the current zero-crossing position detected and estimated by the conventional voltage zero-crossing detection module and the actual current zero-crossing position, making it difficult to control the conduction and closing of the thyristor in time, and difficult to maintain a constant output power. Utility Model Content

[0005] In order to solve the above technical problems, the utility model provides a power control circuit and electronic equipment based on thyristor.

[0006] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0007] A power control circuit based on thyristor comprises a single chip microcomputer, a heating wire, a thyristor, a voltage and current processing module, a zero-crossing detection module and a voltage detection module, wherein: the voltage and current processing module, the thyristor, the heating wire and the zero-crossing detection module are all connected to an AC input power supply, the single chip microcomputer is connected to an optical coupling module, the voltage and current processing module, the heating wire, the optical coupling module and the zero-crossing detection module are all connected to the thyristor, the voltage and current processing module is connected to the optical coupling module, and the zero-crossing detection module, the voltage detection module and the voltage and current processing module are respectively connected to the single chip microcomputer.

[0008] As a further improvement, the voltage and current processing module includes a rectifier module, a first filter module, a step-down module, and a second filter module connected in sequence. The rectifier module is connected to the thyristor and the AC input power supply. The second filter module is respectively connected to the single-chip microcomputer, the zero-crossing detection module, and the optocoupler module. The first filter module is connected to the voltage detection module.

[0009] As a further improvement, the thyristor is a first bidirectional thyristor, which has an electrode T1, an electrode T2 and a control electrode G, the electrode T1 is connected to the heating wire, the electrode T2 is connected to the AC input power supply, the control electrode G is connected to the optocoupler module, and the control electrode G is connected to the electrode T1 through a resistor R11.

[0010] As a further improvement, the optocoupler module includes a photodiode, a thyristor, a first pin, a second pin, a third pin and a fourth pin, the positive electrode of the photodiode is connected to the first pin, the negative electrode of the photodiode is connected to the second pin, the thyristor has an electrode A and an electrode K, the electrode A is connected to the third pin, the electrode K is connected to the fourth pin, the third pin is connected to the control electrode G of the first bidirectional thyristor, and the fourth pin is connected to the electrode T2 of the first bidirectional thyristor.

[0011] As a further improvement, the thyristor is a photosensitive bidirectional thyristor.

[0012] As a further improvement, resistors R7 and R8 are sequentially connected between the electrode T2 of the first bidirectional thyristor and the fourth pin in the optical coupling module, and the second pin is externally connected to a resistor R10.

[0013] As a further improvement, the zero-crossing detection module includes a transistor Q2 and a diode D1, the diode D1 is connected in parallel between the positive and negative electrodes of the diode D1, the negative electrode of the diode D1 is connected to the substrate of the transistor Q2 and then connected to the resistor R13, the resistor R13 is connected to the resistor R9, the resistor R9 is connected to the electrode T2 of the first bidirectional thyristor, the collector of the transistor Q2 is connected to the resistor R12, and the emitter of the transistor Q2 is grounded.

[0014] As a further improvement, the rectifier module includes four diodes connected in a closed loop in sequence, and the first filter module and the second filter module are respectively composed of capacitors connected in parallel.

[0015] As a further improvement, the step-down module includes a resistor R1, a resistor R3, a resistor R4, a resistor R6 and a capacitor C2. The resistors R1, R3 and R6 are connected in series in sequence. The resistor R1 is connected to an external power supply. The resistor R4 is connected to the resistor R3 and the resistor R6. One end of the capacitor C2 is connected to the resistor R4, and the other end of the capacitor C2 is connected to the resistor R6 and grounded.

[0016] An electronic device comprises the above-mentioned thyristor-based power control circuit.

[0017] Compared with the prior art, the utility model has the following beneficial technical effects:

[0018] A single-chip microcomputer is used for control to collect changes in input voltage. In combination with a zero-crossing detection module, zero-crossing detection control is implemented to achieve precise control of the first bidirectional thyristor. Accurate collection of the single-chip microcomputer is combined with a zero-crossing detection module to control the first bidirectional thyristor for precise control. The output is adjusted using the ratio of the number of zero-crossing conduction and shutdown of the first bidirectional thyristor to maintain the output power within a relatively constant range. The sharp increase in the heating wire voltage is promptly controlled to avoid damage to the electronic equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the module connection principle of the utility model;

[0020] Figure 2 This is a schematic diagram of the connection principle of the first bidirectional thyristor and the optocoupler module of the utility model;

[0021] Figure 3 This is a schematic diagram of the circuit principle of the zero-crossing detection module in the utility model;

[0022] Figure 4 This is a schematic diagram of the circuit connection principle of the rectifier module and the filter module in the utility model;

[0023] Figure 5 This is a schematic diagram of the circuit principle of the step-down module in the utility model. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0025] In the description of the present utility model, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like are involved, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present utility model, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0026] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be directly connected or indirectly connected through an intermediate medium. It can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0027] Embodiment 1

[0028] refer to Figure 1 , 4 As shown in Figure 5, a power control circuit based on thyristor includes a single-chip microcomputer, a heating wire, a thyristor Q1, a voltage and current processing module, a zero-crossing detection module and a voltage detection module, wherein: the voltage and current processing module, the thyristor, the heating wire and the zero-crossing detection module are all connected to the AC input power supply, the single-chip microcomputer is connected to an optical coupling module, the voltage and current processing module, the heating wire, the optical coupling module and the zero-crossing detection module are all connected to the thyristor, the voltage and current processing module is connected to the optical coupling module, and the zero-crossing detection module, the voltage detection module and the voltage and current processing module are respectively connected to the single-chip microcomputer. The single-chip microcomputer can collect the change of the input voltage and is used to receive and send various data and instructions. There is no specific limitation on the model of the single-chip microcomputer. It can be used in various types in the prior art. The size and model are selected according to the specifications of the circuit to which it is applied. Usually, a 5V power supply is input to ensure normal operation.

[0029] The current signal is output to the single-chip microcomputer in real time through the electric zero-crossing detection module, and the current zero-crossing position of the output signal is accurately detected by the cooperation of the control single-chip microcomputer, and the conduction angle of the thyristor is adjusted according to the current zero-crossing position, thereby realizing the on-off control of the thyristor. Since the current zero-crossing position can be accurately detected, the pulse width of the thyristor can be very narrow to enable the thyristor to be effectively turned on. The current zero-crossing position is estimated by using the power supply voltage waveform actually detected by the voltage zero-crossing detection module, and the conduction angle of the thyristor is adjusted according to the estimated current zero-crossing position to control the conduction of the thyristor, realizing precise control, and controlling the number of times the thyristor is turned on and off, thereby achieving the control of the output power.

[0030] The voltage and current processing module includes a rectifier module, a first filter module, a step-down module, and a second filter module connected in sequence. The rectifier module is connected to the thyristor and the AC input power supply. The second filter module is respectively connected to the single-chip microcomputer, the zero-crossing detection module, and the optocoupler module. The first filter module is connected to the voltage detection module. The AC input power supply is rectified by the rectifier module, and then filtered and stepped down by the filter module and the step-down module to ensure that a stable voltage is provided to the single-chip microcomputer and the optocoupler module. The optocoupler module realizes electrical isolation between the input and output ends through optical isolation, ensuring that cross interference does not occur when the signal is transmitted between interconnected circuits, and realizing electrical isolation to prevent electrical shock or excessive voltage from damaging the circuit. The voltage detection module can use an existing known module.

[0031] The rectifier module includes four diodes connected in a closed loop in sequence, such as diode D2, diode D3, diode D4 and diode D5, the cathode of diode D2 is connected to the anode of diode D3, the cathode of diode D3 is connected to the cathode of diode D4, the anode of diode D4 is connected to the cathode of diode D5, the anode of diode D5 is connected to the anode of diode D2, and the anode of diode D2 and the cathode of diode D5 are externally connected to an AC input power supply.

[0032] The first filter module includes a capacitor E1, one end of which is connected to the cathode of the diode D3 and the diode D4, and the other end of which is connected to the anode of the diode D2 and the diode D5, to play a filtering role and eliminate noise and clutter interference in the signal. The second filter module can also be composed of a capacitor, which can be connected in parallel with the step-down module. The first filter module and the second filter module are only defined by name for the convenience of distinguishing descriptions, and their circuit structures are the same.

[0033] The step-down module includes a resistor R1, a resistor R3, a resistor R4, a resistor R6 and a capacitor C2, wherein the resistors R1, R3 and R6 are connected in series in sequence, the resistor R1 is externally connected to a power source, the resistor R4 is connected to the resistor R3 and the resistor R6, one end of the capacitor C2 is connected to the resistor R4, and the other end of the capacitor C2 is connected to the resistor R6 and grounded. The voltage is stepped down and divided by using the resistors R1, R3 and R6 connected in series.

[0034] Embodiment 2

[0035] refer to Figure 1-5 As shown, the thyristor is a first bidirectional thyristor, which has an electrode T1, an electrode T2 and a control electrode G, the electrode T1 is connected to the heating wire 6, the electrode T2 is connected to the AC input power supply, the control electrode G is connected to the optical coupling module, and the control electrode G is connected to the electrode T1 through a resistor R11.

[0036] For the first bidirectional thyristor, the conduction condition is generally: when there is a sufficient voltage between the control electrode G and the electrode T1 and sufficient conduction current can be provided, the thyristor can be turned on. This voltage can be positive or negative, and has nothing to do with the current direction between the electrode T1 and the electrode T2. Because the bidirectional thyristor can conduct in both directions, there is no positive pole or negative pole, but there is a distinction between the electrode T1 and the electrode T2.

[0037] Apply a positive or negative voltage to electrode T1 and electrode T2, and it can be triggered to conduct regardless of whether the trigger signal is positive or negative. Therefore, it has the following four triggering modes:

[0038] 1. When the voltage applied by electrode T2 to T1 is a positive voltage, and the voltage applied by control electrode G to the first electrode T1 is also a positive trigger signal, after the bidirectional thyristor is triggered and turned on, the current flows from T2 to T1.

[0039] 2. If the main electrode T2 is still applied with a forward voltage and the trigger signal is changed to a reverse signal, after the bidirectional thyristor is triggered and turned on, the direction of the on-state current is still from T2 to T1.

[0040] 3. When a reverse voltage is applied to the two electrodes, a forward trigger signal is input, and after the bidirectional thyristor is turned on, the on-state current flows from T1 to T2.

[0041] 4. When the reverse voltage is still applied to the two electrodes and the reverse trigger signal is input, after the bidirectional thyristor is turned on, the on-state current still flows from T1 to T2.

[0042] The trigger signal in the single-chip control system is loaded to the control electrode of the first bidirectional thyristor by using an optical coupling module, so as to reduce the driving power and the interference generated when the thyristor is triggered.

[0043] The optocoupler module includes a photodiode 5, a thyristor Q3, a first pin 1, a second pin 2, a third pin 3 and a fourth pin 4, the positive electrode of the photodiode 5 is connected to the first pin 1, the negative electrode of the photodiode 5 is connected to the second pin 2, the thyristor Q3 has an electrode A and an electrode K, the electrode A is connected to the third pin 3, the electrode K is connected to the fourth pin 4, the third pin 3 is connected to the control electrode G of the first bidirectional thyristor, the fourth pin 4 is connected to the electrode T2 of the first bidirectional thyristor, and resistors R7 and R8 are connected in sequence between the electrode T2 of the first bidirectional thyristor and the fourth pin 4 in the optocoupler module, the second pin 2 is externally connected to a resistor R10, and the thyristor Q3 is a photosensitive bidirectional thyristor.

[0044] When the photosensitive bidirectional thyristor senses the light emitted by the photodiode 5, the photosensitive bidirectional thyristor generates a trigger voltage signal and transmits the trigger voltage signal to the control electrode G of the first bidirectional thyristor, and then the first bidirectional thyristor conducts the circuit between the third pin 3 and the fourth pin 4, thereby controlling the power supply of the heating wire to control the operation of the heating wire. When the photodiode is not powered, the photodiode does not emit light, and the power supply of the first bidirectional thyristor is cut off, and the first bidirectional thyristor is turned off.

[0045] Embodiment 3

[0046] refer to Figure 1-5 As shown, the zero-crossing detection module includes a transistor Q2 and a diode D1, the diode D1 is connected in parallel between the positive and negative electrodes of the diode D1, the negative electrode of the diode D1 is connected to the substrate of the transistor Q2 and then connected to the resistor R13, the resistor R13 is connected to the resistor R9, the resistor R9 is connected to the electrode T2 of the first bidirectional thyristor, the collector of the transistor Q2 is connected to the resistor R12, and the emitter of the transistor Q2 is grounded. The current signal is transmitted to the single-chip microcomputer through the zero-crossing detection module, the single-chip microcomputer accurately collects the change of the input voltage, and detects the current zero-crossing position of the output signal in combination with the control of the single-chip microcomputer, and adjusts the conduction angle of the first bidirectional thyristor according to the current zero-crossing position, thereby realizing the on-off control of the first bidirectional thyristor, adjusting the ratio of the number of zero-crossing conduction and judgment of the first bidirectional thyristor, so as to realize the control of the output power. When the voltage rises sharply, the output power can also be adjusted in time through control to keep the output power in a relatively constant range, thereby avoiding the temperature of the electrical equipment from rising sharply.

[0047] In addition, the utility model also discloses an electronic device, including the above-mentioned thyristor-based power control circuit, which plays an effective role in controlling the output power and playing a protective role.

[0048] It should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A power control circuit based on thyristor, characterized in that: It includes a single-chip microcomputer, a heating wire, a thyristor, a voltage and current processing module, a zero-crossing detection module and a voltage detection module, wherein: the voltage and current processing module, the thyristor, the heating wire and the zero-crossing detection module are all connected to an AC input power supply, the single-chip microcomputer is connected to an optical coupling module, the voltage and current processing module, the heating wire, the optical coupling module and the zero-crossing detection module are all connected to the thyristor, the voltage and current processing module is connected to the optical coupling module, and the zero-crossing detection module, the voltage detection module and the voltage and current processing module are respectively connected to the single-chip microcomputer.

2. The thyristor-based power control circuit according to claim 1, characterized in that: The voltage and current processing module includes a rectifier module, a first filter module, a step-down module, and a second filter module connected in sequence. The rectifier module is connected to the thyristor and the AC input power supply. The second filter module is respectively connected to the single-chip microcomputer, the zero-crossing detection module, and the optocoupler module. The first filter module is connected to the voltage detection module.

3. The thyristor-based power control circuit according to claim 1, characterized in that: The thyristor is a first bidirectional thyristor, which has an electrode T1, an electrode T2 and a control electrode G. The electrode T1 is connected to the heating wire, the electrode T2 is connected to the AC input power supply, the control electrode G is connected to the optical coupling module, and the control electrode G is connected to the electrode T1 through a resistor R11.

4. The thyristor-based power control circuit according to claim 3, characterized in that: The optocoupler module includes a photodiode, a thyristor, a first pin, a second pin, a third pin and a fourth pin, the positive electrode of the photodiode is connected to the first pin, the negative electrode of the photodiode is connected to the second pin, the thyristor has an electrode A and an electrode K, the electrode A is connected to the third pin, the electrode K is connected to the fourth pin, the third pin is connected to the control electrode G of the first bidirectional thyristor, and the fourth pin is connected to the electrode T2 of the first bidirectional thyristor.

5. The thyristor-based power control circuit according to claim 4, characterized in that: The thyristor is a photosensitive bidirectional thyristor.

6. The thyristor-based power control circuit according to claim 4, characterized in that: Resistors R7 and R8 are sequentially connected between the electrode T2 of the first bidirectional thyristor and the fourth pin in the optical coupling module, and the second pin is externally connected to a resistor R10.

7. The thyristor-based power control circuit according to claim 3, characterized in that: The zero-crossing detection module includes a transistor Q2 and a diode D1, wherein the diode D1 is connected in parallel between the positive electrode and the negative electrode of the diode D1, wherein the negative electrode of the diode D1 is connected to the substrate of the transistor Q2 and then connected to the resistor R13, the resistor R13 is connected to the resistor R9, the resistor R9 is connected to the electrode T2 of the first bidirectional thyristor, the collector of the transistor Q2 is connected to the resistor R12, and the emitter of the transistor Q2 is grounded.

8. The thyristor-based power control circuit according to claim 2, characterized in that: The rectifier module includes four diodes connected in a closed loop in sequence, and the first filter module and the second filter module are respectively composed of capacitors connected in parallel.

9. The thyristor-based power control circuit according to claim 2, characterized in that: The step-down module includes a resistor R1, a resistor R3, a resistor R4, a resistor R6 and a capacitor C2. The resistors R1, R3 and R6 are connected in series in sequence. The resistor R1 is externally connected to a power supply. The resistor R4 is connected to the resistor R3 and the resistor R6. One end of the capacitor C2 is connected to the resistor R4. The other end of the capacitor C2 is connected to the resistor R6 and is grounded.

10. An electronic device, characterized in that: A power control circuit based on thyristor comprising any one of claims 1-9.

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