Zero cross detection circuit and silicon controlled rectifier voltage stabilizing device

Abstract

The utility model discloses a zero cross detection circuit and a silicon controlled rectifier voltage stabilization device, the zero cross detection circuit comprises a rectification circuit, an optocoupler circuit and a constant current circuit, the input end of the rectification circuit is connected with the first terminal of an AC power supply, and the rectification circuit is used for rectifying the AC output by the AC power supply and outputting a positive half cycle current; the output end of the rectifying circuit is connected with the input end of the optical coupling circuit, and the output end of the optical coupling circuit is connected with the zero-cross detection signal receiving port; the silicon controlled rectifier voltage stabilizing device comprises a silicon controlled rectifier, a microprocessor and a zero cross detection circuit. According to the utility model, the function of accurate zero-cross detection on the alternating current output by the alternating current power supply is realized, and the service life of the optocoupler circuit is prolonged through the protection effects of the constant current circuit and the current limiting circuit; the silicon controlled rectifier voltage-stabilizing device can accurately control the on-off of the silicon controlled rectifier according to the zero-cross detection signal, thereby realizing a voltage-stabilizing function and improving the stability and reliability of a power system.

Description

Technical Field

[0001] This utility model belongs to the field of circuit testing technology, specifically relating to a zero-crossing detection circuit and a silicon controlled rectifier voltage regulator. Background Technology

[0002] Zero-crossing detection refers to the detection performed by an AC system when a waveform crosses zero as it transitions from the positive half-cycle to the negative half-cycle. Zero-crossing detection signals have wide applications in control, facilitating the control of load switching on and off.

[0003] In existing technologies, zero-crossing detection typically uses optocoupler circuits for sampling. However, since the mains power is a sinusoidal wave with voltage variations between 0-310V, current-limiting resistors are usually installed to protect the LEDs from excessive voltage fluctuations. But a fixed-value current-limiting resistor may cause excessive current at high voltages, burning out the optocoupler, and excessive current variations can affect the lifespan of the LEDs in the optocoupler.

[0004] Furthermore, triacs can be used as power driving devices in microcontroller control systems. Because triacs do not have reverse voltage withstand issues and their control circuits are simple, they are suitable for use as AC contactless switches. However, triacs typically connect high-power appliances and are connected to high-voltage networks, making the interference immunity of the trigger circuit crucial.

[0005] To address this, a zero-crossing detection circuit and a thyristor voltage regulator are proposed. Utility Model Content

[0006] The purpose of this invention is to provide a zero-crossing detection circuit and a silicon controlled rectifier (SCR) voltage regulator to solve the technical problem of performance degradation of the optocoupler circuit caused by the unstable current in the optocoupler circuit in the existing zero-crossing detection circuit.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A zero-crossing detection circuit includes a rectifier circuit, an optocoupler circuit, and a constant current circuit.

[0009] The input terminal of the rectifier circuit is connected to the first terminal of the AC power supply to rectify the AC power output from the AC power supply and output a positive half-cycle current.

[0010] The output of the rectifier circuit is connected to the input of the optocoupler circuit, and the output of the optocoupler circuit is connected to the zero-crossing detection signal receiving port. Based on the change of the positive half-cycle current, a first-level signal or a second-level signal is output to the zero-crossing detection signal receiving port to realize zero-crossing detection.

[0011] The constant current circuit is connected to the second terminal of the optocoupler circuit and the AC power supply respectively. During the period when the optocoupler circuit outputs the first level signal, the current of the optocoupler circuit is maintained at a constant value to protect the optocoupler circuit from the impact of current changes.

[0012] As a further embodiment of this utility model, the optocoupler circuit includes an optocoupler and a pull-up resistor. The positive input terminal of the optocoupler is connected to the output terminal of the rectifier circuit, the negative input terminal of the optocoupler is connected to the constant current circuit, one end of the positive output terminal of the optocoupler is connected to one end of the pull-up resistor and the zero-crossing detection signal receiving port, the other end of the pull-up resistor is connected to a preset power supply, and the negative output terminal of the optocoupler is grounded.

[0013] As a further embodiment of this utility model, the circuit also includes a current limiting circuit. The input terminal of the rectifier circuit is connected to the input terminal of the optocoupler circuit through the current limiting circuit. The current limiting circuit is used to reduce the positive half-cycle current and output it to the optocoupler circuit, thereby further protecting the optocoupler circuit.

[0014] As a further embodiment of this utility model, the current limiting circuit consists of a current limiting resistor. The positive terminal of the AC power supply is connected to the input terminal of the rectifier circuit through the current limiting resistor. The output terminal of the rectifier circuit is then connected to the input terminal of the optocoupler circuit. The resistance value of the current limiting resistor can be calculated and selected according to the current requirements of the optocoupler circuit and the power supply voltage to ensure that the current is within an appropriate range.

[0015] As a preferred embodiment of this utility model, the rectifier circuit consists of a rectifier diode and a filter capacitor. The positive terminal of the AC power supply is connected to the positive terminal of the filter capacitor through the rectifier diode, and the negative terminal of the filter capacitor is grounded. When the positive half-cycle of the AC power supply arrives, the rectifier diode is turned on, and the current flows through the rectifier diode to the filter capacitor to charge the capacitor. When the negative half-cycle of the AC power supply arrives, the rectifier diode is turned off, and the current cannot flow through the rectifier diode to the filter capacitor. The filter capacitor can maintain DC output for a period of time through its discharge characteristics.

[0016] As a preferred embodiment of this utility model, the constant current circuit consists of an operational amplifier and a resistor. The non-inverting input terminal of the operational amplifier is connected to the input terminal of the optocoupler circuit, and the inverting input terminal is connected to ground through a resistor. The output terminal of the operational amplifier is connected to the negative input terminal of the optocoupler circuit through another resistor. When the optocoupler circuit outputs a first-level signal, the operational amplifier will adjust its output voltage according to the resistance value of the feedback resistor, thereby maintaining the constant current of the optocoupler circuit.

[0017] This utility model also proposes a thyristor voltage regulator: including a housing and a thyristor, a microprocessor, and the aforementioned zero-crossing detection circuit fixedly installed inside the housing. The output terminal of the zero-crossing detection circuit is connected to the input terminal of the microprocessor, and the output terminal of the microprocessor is connected to the thyristor. The zero-crossing detection circuit is used to output a first-level signal or a second-level signal to the microprocessor. The microprocessor is used to generate a control signal based on the first-level signal or the second-level signal and send the control signal to the thyristor to control the on / off state of the thyristor and realize the voltage regulation function.

[0018] Compared with the prior art, the zero-crossing detection circuit and thyristor voltage regulator provided by this utility model have the following beneficial effects:

[0019] This invention, by setting a constant current circuit, enables the optocoupler circuit to maintain a constant current during the output of the first level signal, thereby protecting the optocoupler circuit from the impact of current changes and extending the service life of the optocoupler circuit.

[0020] This invention further reduces the current input to the optocoupler circuit by setting a current limiting circuit, thus further protecting the optocoupler circuit.

[0021] This invention utilizes the output signal of a zero-detection circuit to control the on / off state of a thyristor, thereby achieving voltage regulation and improving the stability and reliability of the circuit. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only examples of embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is an electrical connection block diagram of the zero-crossing detection circuit in an embodiment of this utility model;

[0024] Figure 2 This is an electrical connection block diagram of the thyristor voltage regulator in an embodiment of this utility model;

[0025] Figure 3 This is a schematic diagram of the structure of the thyristor voltage regulator in the embodiment of this utility model.

[0026] Reference numerals: 1. Outer shell. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0028] In the description of the embodiments of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of the present 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 limitations on the embodiments of the present invention.

[0029] In the description of the embodiments of the present 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, an integral connection, or a detachable connection; they can refer to the internal connection of two components; they can refer to a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present invention should be understood according to the specific circumstances.

[0030] See appendix Figure 1-2 As shown, this embodiment of the utility model includes a rectifier circuit, an optocoupler circuit, and a constant current circuit.

[0031] The input terminal of the rectifier circuit is connected to the first terminal of the AC power supply to rectify the AC power output from the AC power supply and output positive half-cycle current.

[0032] The output of the rectifier circuit is connected to the input of the optocoupler circuit, and the output of the optocoupler circuit is connected to the zero-crossing detection signal receiving port. It is used to output a first-level signal or a second-level signal to the zero-crossing detection signal receiving port according to the change of the positive half-cycle current, so as to realize zero-crossing detection.

[0033] The constant current circuit is connected to the second terminal of the optocoupler circuit and the AC power supply respectively. It is used to maintain the current of the optocoupler circuit at a constant value during the output of the first level signal of the optocoupler circuit, so as to protect the optocoupler circuit from the impact of current changes.

[0034] The above technical solution, by setting a constant current circuit, enables the optocoupler circuit to maintain a constant current during the output of the first level signal, thereby protecting the optocoupler circuit from the impact of current changes and extending the service life of the optocoupler circuit.

[0035] In this embodiment of the invention, the optocoupler circuit includes an optocoupler and a pull-up resistor. The positive input terminal of the optocoupler is connected to the output terminal of the rectifier circuit, the negative input terminal of the optocoupler is connected to the constant current circuit, one end of the positive output terminal of the optocoupler is connected to one end of the pull-up resistor and the zero-crossing detection signal receiving port, the other end of the pull-up resistor is connected to a preset power supply, and the negative output terminal of the optocoupler is grounded.

[0036] The optocoupler circuit consists of an optocoupler and a pull-up resistor. Utilizing the switching characteristics of the optocoupler, it outputs either a first-level signal or a second-level signal based on changes in the positive half-cycle current. The pull-up resistor ensures the stability of the optocoupler's output level, enabling the zero-crossing detection signal receiving port to accurately receive the zero-crossing signal. Simultaneously, the optocoupler's isolation function protects subsequent circuitry from high-voltage or high-current surges.

[0037] This utility model embodiment of a zero-crossing detection circuit also includes a current limiting circuit. The input terminal of the rectifier circuit is connected to the input terminal of the optocoupler circuit through the current limiting circuit. The current limiting circuit is used to reduce the positive half-cycle current and output it to the optocoupler circuit, thereby further protecting the optocoupler circuit.

[0038] The current limiting circuit consists of a current limiting resistor. The positive terminal of the AC power supply is connected to the input terminal of the rectifier circuit through the current limiting resistor. The output terminal of the rectifier circuit is then connected to the input terminal of the optocoupler circuit. The resistance value of the current limiting resistor can be calculated and selected according to the current requirements of the optocoupler circuit and the power supply voltage to ensure that the current is within an appropriate range.

[0039] In this embodiment of the invention, the current-limiting circuit consists of a current-limiting resistor, which limits the magnitude of the positive half-cycle current of the input optocoupler circuit, further protecting the optocoupler circuit from damage caused by excessive current. The resistance value of the current-limiting resistor is precisely calculated to ensure that the current is within the withstand range of the optocoupler circuit.

[0040] The rectifier circuit consists of a rectifier diode and a filter capacitor. The positive terminal of the AC power supply is connected to the positive terminal of the filter capacitor through the rectifier diode, and the negative terminal of the filter capacitor is grounded. When the positive half-cycle of the AC power supply arrives, the rectifier diode conducts, and the current flows through the rectifier diode to the filter capacitor to charge the capacitor. When the negative half-cycle of the AC power supply arrives, the rectifier diode is cut off, and the current cannot flow through the rectifier diode to the filter capacitor. The filter capacitor can maintain DC output for a period of time through its discharge characteristics.

[0041] The rectifier circuit consists of rectifier diodes and filter capacitors. It effectively rectifies the AC power output from the AC power supply into a positive half-cycle current and stabilizes the DC power output (within the positive half-cycle) through the filter capacitor. This not only provides a stable input current for the optocoupler circuit but also reduces the impact of current fluctuations on subsequent circuits.

[0042] The constant current circuit consists of an operational amplifier and resistors. The non-inverting input of the operational amplifier is connected to the input of the optocoupler circuit, and the inverting input is connected to ground through a resistor. The output of the operational amplifier is connected to the negative input of the optocoupler circuit through another resistor. When the optocoupler circuit outputs the first level signal, the operational amplifier will adjust its output voltage according to the resistance value of the feedback resistor, thereby maintaining the constant current of the optocoupler circuit.

[0043] The constant current circuit consists of an operational amplifier and resistors. When the optocoupler outputs a first-level signal, the operational amplifier adjusts its output voltage to maintain a constant current in the optocoupler. This effectively prevents damage to the optocoupler due to sudden current changes and extends its lifespan.

[0044] like Figure 1 As shown, this utility model embodiment also provides a thyristor voltage regulator: including a housing 1 and a thyristor, a microprocessor, and the aforementioned zero-crossing detection circuit fixedly installed inside the housing 1. The output terminal of the zero-crossing detection circuit is connected to the input terminal of the microprocessor, and the output terminal of the microprocessor is connected to the thyristor. The zero-crossing detection circuit is used to output a first level signal or a second level signal to the microprocessor. The microprocessor is used to generate a control signal according to the first level signal or the second level signal and send the control signal to the thyristor to control the on / off state of the thyristor and realize the voltage regulation function.

[0045] The thyristor can be the EUPEC T-series thyristor, and the microprocessor can be the Intel 8088 microprocessor.

[0046] The working process of this thyristor voltage regulator is as follows:

[0047] 1. The AC power supply outputs positive half-cycle current through the rectifier circuit.

[0048] 2. The positive half-cycle current is input to the optocoupler circuit after passing through the current limiting circuit.

[0049] 3. The optocoupler circuit outputs a first-level signal or a second-level signal to the zero-crossing detection signal receiving port based on the change in the positive half-cycle current.

[0050] 4. The zero-crossing detection signal receiving port transmits the signal to the microprocessor.

[0051] 5. The microprocessor generates control signals based on the received level signals.

[0052] 6. The control signal is sent to the thyristor to control its on / off state, thereby achieving the voltage regulation function.

[0053] In summary, the present invention provides a zero-crossing detection circuit and a thyristor voltage regulator, which realizes the function of accurately detecting the zero-crossing of AC power output; through the protection of constant current circuit and current limiting circuit, the service life of optocoupler circuit is extended; the thyristor voltage regulator can accurately control the on / off state of thyristor according to the zero-crossing detection signal, realize the voltage regulation function, and improve the stability and reliability of power system.

[0054] The foregoing has shown and described the basic principles of the present invention. The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. The above embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Any modifications, equivalent substitutions, and improvements made within the scope of the present invention without departing from the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A zero-crossing detection circuit, characterized in that: It includes rectifier circuits, optocoupler circuits, and constant current circuits, among which: The input terminal of the rectifier circuit is connected to the first terminal of the AC power supply to rectify the AC power output from the AC power supply and output a positive half-cycle current. The output terminal of the rectifier circuit is connected to the input terminal of the optocoupler circuit, and the output terminal of the optocoupler circuit is connected to the zero-crossing detection signal receiving port. The first level signal or the second level signal is output to the zero-crossing detection signal receiving port according to the change of the positive half-cycle current. The constant current circuit is connected to the second terminal of the optocoupler circuit and the AC power supply respectively, and maintains the current of the optocoupler circuit at a constant value during the period when the optocoupler circuit outputs the first level signal.

2. The zero-crossing detection circuit according to claim 1, characterized in that: The optocoupler circuit includes an optocoupler and a pull-up resistor. The positive input terminal of the optocoupler is connected to the output terminal of the rectifier circuit, the negative input terminal of the optocoupler is connected to the constant current circuit, one end of the positive output terminal of the optocoupler is connected to one end of the pull-up resistor and the zero-crossing detection signal receiving port, the other end of the pull-up resistor is connected to a preset power supply, and the negative output terminal of the optocoupler is grounded.

3. A zero-crossing detection circuit according to claim 2, characterized in that: It also includes a current limiting circuit. The input terminal of the rectifier circuit is connected to the input terminal of the optocoupler circuit through the current limiting circuit. The current limiting circuit is used to reduce the positive half-cycle current and output it to the optocoupler circuit.

4. A zero-crossing detection circuit according to claim 3, characterized in that: The current limiting circuit consists of a current limiting resistor. The positive terminal of the AC power supply is connected to the input terminal of the rectifier circuit through the current limiting resistor. The output terminal of the rectifier circuit is then connected to the input terminal of the optocoupler circuit.

5. A zero-crossing detection circuit according to claim 2, characterized in that: The rectifier circuit consists of a rectifier diode and a filter capacitor. The positive terminal of the AC power supply is connected to the positive terminal of the filter capacitor through the rectifier diode, and the negative terminal of the filter capacitor is grounded. When the positive half-cycle of the AC power supply arrives, the rectifier diode conducts, and the current flows through the rectifier diode to the filter capacitor to charge the capacitor. When the negative half-cycle of the AC power supply arrives, the rectifier diode is cut off, and the current cannot flow through the rectifier diode to the filter capacitor. The filter capacitor can maintain DC output for a period of time through its discharge characteristics.

6. A zero-crossing detection circuit according to claim 2, characterized in that: The constant current circuit consists of an operational amplifier and a resistor. The non-inverting input of the operational amplifier is connected to the input of the optocoupler circuit, and the inverting input is connected to ground through a resistor. The output of the operational amplifier is connected to the negative input of the optocoupler circuit through another resistor. When the optocoupler circuit outputs a first-level signal, the operational amplifier adjusts its output voltage according to the resistance value of the feedback resistor.

7. A thyristor voltage regulator, characterized in that: The device includes a housing (1) and a thyristor, a microprocessor, and a zero-crossing detection circuit as described in any one of claims 1-6, all fixedly installed inside the housing (1). The output terminal of the zero-crossing detection circuit is connected to the input terminal of the microprocessor, and the output terminal of the microprocessor is connected to the thyristor. The zero-crossing detection circuit is used to output a first-level signal or a second-level signal to the microprocessor. The microprocessor is used to generate a control signal based on the first-level signal or the second-level signal and send the control signal to the thyristor to control the switching on and off of the thyristor and realize the voltage regulation function.

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