Over-voltage and under-voltage protection circuit, substrate and self-recovery over-voltage and under-voltage protector

Abstract

The utility model provides an overvoltage and undervoltage protection circuit, a substrate and a self-recovery overvoltage and undervoltage protector. The circuit comprises a step-down circuit, a voltage stabilizing circuit, a main control circuit, a driving circuit, a zero-cross detection circuit, a voltage detection circuit and a display circuit, the step-down circuit receives the AC voltage and converts the AC voltage into a first voltage; the voltage stabilizing circuit receives the first voltage and converts the first voltage into second voltage; the zero-crossing detection circuit receives and outputs a zero-crossing indication signal according to the AC voltage; the voltage detection circuit receives the AC voltage and divides the AC voltage to obtain a power grid acquisition voltage; the main control circuit outputs a control signal according to the zero-crossing indication signal; the power grid voltage and fault information are output according to the power grid acquisition voltage, and the display circuit is driven to display; the drive circuit controls the relay to be in a closed state or an off state according to the control signal. Zero-crossing detection is carried out on an alternating current signal through the zero-crossing detection circuit, opening or closing operation is carried out at a zero-crossing point, and the service life of equipment is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of relay control, and particularly relates to an over-voltage and under-voltage protection circuit, a substrate and a self-resetting over-voltage and under-voltage protector. BACKGROUND

[0002] In an alternating current system, the waveform of an alternating current signal is a sine wave, and usually includes three-phase alternating current signals, and the phases of each alternating current signal are 120° apart. Zero-crossing detection refers to detecting, in an alternating current system, a time at which an alternating current signal waveform passes through zero during a transition of the alternating current signal waveform from a positive half cycle to a negative half cycle or from a negative half cycle to a positive half cycle. Since breaking a circuit breaker at the zero-crossing time of an alternating current can reduce interference to a power supply, is less likely to cause a large breaking arc and noise, and to some extent increases the service life of the circuit breaker, zero-crossing detection has a wide range of applications in alternating current systems, and can be used to select and control the breaking time of a circuit breaker.

[0003] For a self-resetting over-voltage and under-voltage protector, when over-voltage is detected, the self-resetting over-voltage and under-voltage protector waits for the zero-crossing time of an alternating current voltage signal, and when the zero-crossing signal is detected, a control circuit sends a tripping signal to a relay, so that the relay opens the contacts at or near the zero-crossing time of the voltage, cuts off the circuit, and avoids damage to electrical equipment caused by excessive voltage, for example, during a summer peak period, when a voltage of a substation suddenly rises above the normal range due to a fault, the self-resetting over-voltage and under-voltage protector cuts off the power supply at the zero-crossing time of the voltage in the case of over-voltage, and protects electrical equipment such as televisions and refrigerators in the home. Similarly, in the case of under-voltage, the self-resetting over-voltage and under-voltage protector also waits for the zero-crossing time of an alternating current signal, and sends a tripping signal to a relay at the zero-crossing time. In the case of under-voltage, electrical equipment may not work normally, and may even be damaged due to excessive current. Breaking at the zero-crossing time of the current can reduce the arc and impact on the equipment during tripping.

[0004] When the grid voltage returns to the normal range, the self-resetting over-voltage and under-voltage protector detects a signal that the voltage is normal, and then sends a closing signal near the zero-crossing time of the alternating current voltage, so that the relay contacts are closed, the circuit is powered, and the normal operation of the electrical equipment is ensured, for example, during a night low-usage period, the voltage may return to normal from under-voltage, at which time the self-resetting over-voltage and under-voltage protector sends a closing signal at the zero-crossing time, so that the electrical equipment resumes operation.

[0005] In summary, the relay is tripped or closed at the zero-crossing point, which is crucial for the self-resetting over / under voltage protector, can effectively improve the reliability and safety of the self-resetting over / under voltage protector during tripping or closing operation, reduce damage to electrical equipment and the relay itself, delay the service life of the equipment, and ensure stable operation of the power system. Utility model content

[0006] The application provides an over / under voltage protection circuit, a substrate and a self-resetting over / under voltage protector to detect the zero-crossing point of an alternating current signal and improve the service life of the equipment.

[0007] In a first aspect, the application provides an over / under voltage protection circuit, which comprises a voltage reduction circuit, a voltage stabilizing circuit, a main control circuit, a driving circuit, an over-zero detection circuit, a voltage detection circuit and a display circuit.

[0008] The voltage reduction circuit is electrically connected with the voltage stabilizing circuit and the driving circuit, and the main control circuit is electrically connected with the voltage stabilizing circuit, the driving circuit, the over-zero detection circuit, the voltage detection circuit and the display circuit.

[0009] The voltage reduction circuit is configured to receive an alternating current voltage and convert the alternating current voltage into a first voltage, and the first voltage is used to power the driving circuit.

[0010] The voltage stabilizing circuit is configured to receive the first voltage and convert the first voltage into a second voltage, and the second voltage is used to power the main control circuit, the over-zero detection circuit, the voltage detection circuit and the display circuit.

[0011] The over-zero detection circuit is configured to receive the alternating current voltage and output an over-zero indication signal according to the alternating current voltage.

[0012] The voltage detection circuit is configured to receive the alternating current voltage and divide the alternating current voltage to obtain a power grid acquisition voltage.

[0013] The main control circuit is configured to output a control signal according to the over-zero indication signal and transmit the control signal to the driving circuit, and is also configured to output a power grid voltage and fault information according to the power grid acquisition voltage and drive the display circuit to display the power grid voltage and the fault information.

[0014] The driving circuit is configured to control the relay to be in a closed state or an off state according to the control signal.

[0015] In a possible design, the voltage reduction circuit includes a first voltage-dependent resistor, a second voltage-dependent resistor, a third voltage-dependent resistor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a first voltage stabilizing diode, a first inductor, a second inductor, a first resistor, and a switching voltage stabilizer.

[0016] A first end of the second voltage-dependent resistor is electrically connected with a live input end, and a second end of the second voltage-dependent resistor is electrically connected with a zero input end, the live input end and the zero input end being used for accessing the alternating voltage;

[0017] A first end of the first voltage-dependent resistor is electrically connected with the first end of the second voltage-dependent resistor, and a second end of the first voltage-dependent resistor is electrically connected with a first end of the third voltage-dependent resistor, a positive electrode of the first diode, and a negative electrode of the third diode, respectively;

[0018] A second end of the third voltage-dependent resistor is electrically connected with a second end of the second voltage-dependent resistor, a positive electrode of the second diode, and a negative electrode of the fourth diode, respectively;

[0019] A negative electrode of the first diode is electrically connected with a negative electrode of the second diode, a first end of the first inductor, and a positive electrode plate of the first capacitor, respectively;

[0020] A second end of the first inductor is electrically connected with a positive electrode plate of the second capacitor, a first end of the switching voltage stabilizer, a second end of the switching voltage stabilizer, a third end of the switching voltage stabilizer, and a fourth end of the switching voltage stabilizer, respectively;

[0021] A fifth end of the switching voltage stabilizer is electrically connected with a negative electrode of the sixth diode, a negative electrode of the first voltage stabilizing diode, and a positive electrode plate of the fourth capacitor, respectively, a sixth end of the switching voltage stabilizer is electrically connected with a positive electrode of the first voltage stabilizing diode and a first end of the third capacitor, respectively, and a seventh end of the switching voltage stabilizer is electrically connected with an eighth end of the switching voltage stabilizer, a second end of the third capacitor, a negative electrode of the fifth diode, a negative electrode plate of the fourth capacitor, and a first end of the second inductor, respectively;

[0022] A positive electrode of the sixth diode is electrically connected with a second end of the second inductor, a positive electrode plate of the fifth capacitor, and a first end of the first resistor, respectively, and the first end of the first resistor is used as an output end of the voltage reduction circuit and is used for outputting the first voltage;

[0023] A positive electrode of the third diode, a positive electrode of the fourth diode, a negative electrode plate of the first capacitor, a negative electrode plate of the second capacitor, a positive electrode of the fifth diode, a negative electrode plate of the fifth capacitor, and a second end of the first resistor are all grounded.

[0024] In a possible design, the voltage stabilizing circuit includes a seventh diode, a second resistor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, and a linear voltage stabilizer.

[0025] The anode of the seventh diode is configured to access the first voltage, the cathode of the seventh diode is electrically connected with a first end of the second resistor, a second end of the second resistor is electrically connected with a positive plate of the sixth capacitor, a first end of the seventh capacitor, and an input end of the linear voltage stabilizer respectively.

[0026] An output end of the linear voltage stabilizer is electrically connected with a positive plate of the eighth capacitor and a first end of the ninth capacitor respectively, and serves as an output end of the voltage stabilizing circuit and is configured to output the second voltage.

[0027] A negative plate of the sixth capacitor, a second end of the seventh capacitor, a ground end of the linear voltage stabilizer, a negative plate of the eighth capacitor, and a second end of the ninth capacitor are grounded.

[0028] In a possible design, the main control circuit includes a control chip, and the control signal includes a first control signal and a second control signal.

[0029] A fourth end of the control chip is configured to access a reset signal, a seventh end of the control chip is grounded, an eighth end of the control chip is configured to output a clock signal, a ninth end of the control chip is configured to access the second voltage, and a tenth end of the control chip is configured to output or access a data signal.

[0030] A twentieth end of the control chip is configured to access the grid acquisition voltage, a nineteenth end of the control chip is configured to access the zero-crossing indication signal, a fourteenth end of the control chip is configured to output the first control signal, and a thirteenth end of the control chip is configured to output the second control signal.

[0031] In a possible design, the driving circuit includes an eighth diode, a second voltage stabilizing diode, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a tenth capacitor, a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, and a sixth transistor.

[0032] A first end of the eighth diode is configured to access the first voltage, and a second end of the eighth diode is electrically connected with a positive plate of the tenth capacitor, a first end of the first transistor, and a first end of the second transistor respectively.

[0033] The second end of the first transistor is electrically connected with the second end of the fourth transistor, the first end of the second voltage stabilizing diode and the first output end of the driving circuit respectively, and the control end of the first transistor is electrically connected with the first end of the fourth resistor;

[0034] The second end of the second transistor is electrically connected with the second end of the fifth transistor and the second end of the second voltage stabilizing diode, and the second output end of the driving circuit, and the control end of the second transistor is electrically connected with the first end of the third resistor;

[0035] The first end of the second voltage stabilizing diode and the second end of the second voltage stabilizing diode serve as the output end of the driving circuit to control the relay to be in the closed state or the off state;

[0036] The second end of the third transistor is electrically connected with the second end of the third resistor, the first end of the third transistor is electrically connected with the control end of the fourth transistor, and the first end of the fourth transistor is grounded with the first end of the fifth transistor;

[0037] The second end of the sixth transistor is electrically connected with the second end of the fourth resistor, and the first end of the sixth transistor is electrically connected with the control end of the fifth transistor;

[0038] The control end of the third transistor is electrically connected with the first end of the sixth resistor, the control end of the sixth transistor is electrically connected with the first end of the fifth resistor, the second end of the fifth resistor is used for inputting the first control signal, and the second end of the sixth resistor is used for inputting the second control signal.

[0039] In a possible design, the voltage detection circuit comprises a ninth diode, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh capacitor, a twelfth capacitor and an operational amplifier;

[0040] The first end of the ninth diode is electrically connected with a live input end for inputting the alternating voltage, the second end of the ninth diode is electrically connected with the first end of the seventh resistor, the second end of the seventh resistor is electrically connected with the first end of the eighth resistor, and the second end of the eighth resistor is electrically connected with the first end of the ninth resistor, the first end of the eleventh capacitor and the non-inverting input end of the operational amplifier respectively;

[0041] The inverting input end of the operational amplifier is electrically connected with the first end of the tenth resistor, the second end of the tenth resistor is electrically connected with the output end of the operational amplifier and serves as the output end of the voltage detection circuit to output the grid acquisition voltage;

[0042] The power end of the operational amplifier is electrically connected with the first end of the twelfth capacitor, for connecting the second voltage;

[0043] The second end of the ninth resistor, the second end of the eleventh capacitor, the second end of the twelfth capacitor and the ground end of the operational amplifier are grounded.

[0044] In a possible design, the zero-crossing detection circuit includes a twelfth diode, an eleventh diode, an eleventh resistor, a twelfth resistor, a thirteenth capacitor and a photoelectric coupler.

[0045] The first end of the twelfth diode is electrically connected with a live input end, the second end of the twelfth diode is electrically connected with the first end of the eleventh resistor, and the second end of the eleventh resistor is electrically connected with the negative pole of the eleventh diode and the first input end of the photoelectric coupler respectively.

[0046] The positive pole of the eleventh diode is electrically connected with a zero input end and the first output end of the photoelectric coupler respectively.

[0047] The second input end of the photoelectric coupler is electrically connected with the second end of the twelfth resistor and the first end of the thirteenth capacitor respectively, and serves as an output end of the zero-crossing detection circuit, and outputs the zero-crossing indication signal.

[0048] The first end of the twelfth resistor is connected with the second voltage, and the second end of the thirteenth capacitor and the second output end of the photoelectric coupler are grounded.

[0049] In a possible design, the display circuit includes a display screen, a display driver, a thirteenth resistor, a fourteenth resistor and a fourteenth capacitor.

[0050] The first end of the display driver is electrically connected with the thirty-seventh end of the display screen, the second end of the display driver is electrically connected with the thirty-eighth end of the display screen, the third end of the display driver is electrically connected with the thirty-ninth end of the display screen, the fourth end of the display driver is electrically connected with the forty-first end of the display screen, the fifth end of the display driver is electrically connected with the thirty-first end of the display screen, the sixth end of the display driver is electrically connected with the thirty-second end of the display screen, the seventh end of the display driver is electrically connected with the thirty-third end of the display screen, and the eighth end of the display driver is electrically connected with the thirty-fourth end of the display screen.

[0051] The eleventh end of the display driver accesses the clock signal, the twelfth end of the display driver accesses the data signal, the thirteenth end of the display driver is grounded, the sixteenth end of the display driver is electrically connected with the first end of the thirteenth resistor, the seventeenth end of the display driver accesses the second voltage, the eighteenth end of the display driver is electrically connected with the first end of the fourteenth resistor, and the second end of the thirteenth resistor is electrically connected with the second end of the fourteenth resistor and the positive plate of the fourteenth capacitor respectively and used for accessing the second voltage, and the negative plate of the fourteenth capacitor is grounded;

[0052] The twenty-first end of the display driver is electrically connected with the twenty-eighth end of the display screen, the twenty-second end of the display driver is electrically connected with the twenty-seventh end of the display screen, the twenty-third end of the display driver is electrically connected with the twenty-sixth end of the display screen, and the twenty-fourth end of the display driver is electrically connected with the twenty-fifth end of the display screen.

[0053] The twenty-eighth end of the display driver is electrically connected with the sixteenth end of the display screen, the twenty-ninth end of the display driver is electrically connected with the seventeenth end of the display screen, the thirtieth end of the display driver is electrically connected with the eighteenth end of the display screen, the thirty-first end of the display driver is electrically connected with the nineteenth end of the display screen, the thirty-second end of the display driver is electrically connected with the twentieth end of the display screen, the thirty-third end of the display driver is electrically connected with the first end of the display screen, the thirty-fourth end of the display driver is electrically connected with the second end of the display screen, the thirty-fifth end of the display driver is electrically connected with the third end of the display screen, the thirty-sixth end of the display driver is electrically connected with the fourth end of the display screen, the thirty-seventh end of the display driver is electrically connected with the fifth end of the display screen, the thirty-eighth end of the display driver is electrically connected with the sixth end of the display screen, the thirty-ninth end of the display driver is electrically connected with the seventh end of the display screen, and the fortieth end of the display driver is electrically connected with the eighth end of the display screen.

[0054] The forty-first end of the display driver is electrically connected with the twenty-first end of the display screen, the forty-second end of the display driver is electrically connected with the twenty-second end of the display screen, the forty-third end of the display driver is electrically connected with the twenty-third end of the display screen, the forty-fourth end of the display driver is electrically connected with the twenty-fourth end of the display screen, the forty-fifth end of the display driver is electrically connected with the forty-fourth end of the display screen, the forty-sixth end of the display driver is electrically connected with the forty-second end of the display screen, the forty-seventh end of the display driver is electrically connected with the thirty-fifth end of the display screen, and the forty-eighth end of the display driver is electrically connected with the thirty-sixth end of the display screen.

[0055] In a second aspect, the application provides a substrate, comprising the over-voltage and under-voltage protection circuit according to the first aspect.

[0056] In a third aspect, the application provides a self-resetting over-voltage and under-voltage protector, comprising the substrate according to the second aspect and a relay.

[0057] The application has the following beneficial effects:

[0058] In the application, the voltage level conversion is performed by the voltage reduction circuit and the voltage stabilizing circuit to provide power supply for the main control circuit, the driving circuit, the zero-crossing detection circuit, the voltage detection circuit and the display circuit, the zero-crossing detection circuit is used to detect the zero-crossing point of the alternating current signal, the main control circuit outputs a control signal according to the zero-crossing indication signal, the driving circuit controls the relay to be in the closed state or the off state according to the control signal, that is, the relay is tripped or closed at the zero-crossing point, which can improve the service life of the device, the voltage detection circuit is used to collect the power grid voltage signal, the main control circuit also outputs the power grid voltage and the fault information according to the collected power grid voltage, and drives the display circuit to display the power grid voltage and the fault information, so that the power grid voltage and the fault information can be read.

[0059] The application has the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, other embodiments can also be obtained from these drawings.

[0061] Figure 1 A structure schematic diagram of an over-voltage and under-voltage protection circuit provided by the application is shown in the figure;

[0062] Figure 2 A structure schematic diagram of a voltage reduction circuit provided by the application is shown in the figure;

[0063] Figure 3 A structure schematic diagram of a voltage stabilizing circuit provided by the application is shown in the figure;

[0064] Figure 4 A structure schematic diagram of a main control circuit provided by the application is shown in the figure;

[0065] Figure 5 A structure schematic diagram of a driving circuit provided by the application is shown in the figure;

[0066] Figure 6 A structure diagram of a voltage detection circuit provided by an embodiment of the present application is shown in the figure.

[0067] Figure 7 A structure diagram of a zero-crossing detection circuit provided by an embodiment of the present application is shown in the figure.

[0068] Figure 8 A structure diagram of a display circuit provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0069] In the present application, “at least one” means one or more, and “multiple” means two or more. “And / or” describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. The character “ / ” generally represents an “or” relationship between the associated objects before and after it. “At least one of the following” or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c alone can represent: a alone, b alone, c alone, combination of a and b, combination of a and c, combination of b and c, or combination of a, b, and c, where a, b, and c can be single or multiple. In addition, the terms “first” and “second” are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0070] The terms “center”, “longitudinal”, “transverse”, “upper”, “lower”, “left”, “right”, “front”, “back”, and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0071] The terms “connected” and “connected” should be broadly understood, for example, the “connected” or “connected” of the circuit structure can mean not only physical connection, but also electrical connection or signal connection, for example, it can be directly connected, that is, physically connected, or indirectly connected through at least one element in the middle, as long as the circuit is connected, it can also be the internal connection of two elements; In addition to signal connection through the circuit, signal connection through media medium, such as radio waves, can also be referred to. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to specific circumstances.

[0072] In order to detect zero-crossing of an alternating current signal, and to perform opening or closing operation at the zero-crossing, and to improve the service life of the device, an over-voltage and under-voltage protection circuit is provided in the embodiments of the present application, referring to Figure 1 , Figure 1 The structure diagram of the over-voltage and under-voltage protection circuit provided in the embodiments of the present application is shown in FIG. 1, which comprises a voltage reduction circuit 100, a voltage stabilizing circuit 200, a main control circuit 300, a driving circuit 400, a zero-crossing detection circuit 500, a voltage detection circuit 600, and a display circuit 700. Figure 1 The voltage reduction circuit 100 is electrically connected with the voltage stabilizing circuit 200 and the driving circuit 400, and the main control circuit 300 is electrically connected with the voltage stabilizing circuit 200, the driving circuit 400, the zero-crossing detection circuit 500, the voltage detection circuit 600, and the display circuit 700.

[0073] The voltage reduction circuit 100 is configured to receive an alternating current voltage and convert the alternating current voltage into a first voltage V1, and the first voltage V1 is used to power the driving circuit 400.

[0074] The voltage stabilizing circuit 200 is configured to receive the first voltage V1 and convert the first voltage into a second voltage VCC, and the second voltage VCC is used to power the main control circuit 300, the zero-crossing detection circuit 500, the voltage detection circuit 600, and the display circuit 700.

[0075] The zero-crossing detection circuit 500 is configured to receive the alternating current voltage and output a zero-crossing indication signal V_ZERO according to the alternating current voltage.

[0076] The voltage detection circuit 600 is configured to receive the alternating current voltage and divide the alternating current voltage to obtain a grid acquisition voltage V_ADC.

[0077] The main control circuit 300 is configured to output a control signal according to the zero-crossing indication signal V_ZERO and transmit the control signal to the driving circuit 400, and is further configured to output a grid voltage and fault information according to the grid acquisition voltage V_ADC and drive the display circuit 700 to display the grid voltage and the fault information.

[0078] The driving circuit 400 is configured to control the relay to be in a closed state or an off state according to the control signal.

[0079] The alternating current grid system comprises three-phase electric signals, and for each phase electric signal, a circuit breaker can be connected for protection. The over-voltage and under-voltage protection circuit in the present application can be applied to a single-phase product, for example, a self-resetting over-voltage and under-voltage protector.

[0080] The alternating current grid system comprises three-phase electric signals, and for each phase electric signal, a circuit breaker can be connected for protection. The over-voltage and under-voltage protection circuit in the present application can be applied to a single-phase product, for example, a self-resetting over-voltage and under-voltage protector.

[0081] The alternating voltage in the present application is the mains, i.e. 220V alternating voltage. The voltage reduction circuit is a switching power supply, which can convert the alternating voltage into direct current voltage after rectification and filtering, and then convert the direct current voltage into the first voltage V1 after voltage stabilization. The voltage value of the first voltage V1 can be set according to the needs of users, which is not specifically limited in the present application. For example, the first voltage V1 is 16V. In one example, the voltage reduction circuit converts 220V into 16V. The first voltage V1 is used to supply power to the driving circuit 400, and can also be used as the output voltage of the voltage stabilization circuit 200.

[0082] The voltage stabilization circuit 200 receives the first voltage V1 and converts the first voltage into the second voltage VCC. The voltage stabilization circuit 200 can be a LDO (Low Dropout Regulator, low dropout linear voltage regulator) voltage reduction circuit, and the voltage value of the second voltage VCC can be set according to the needs of users, which is not specifically limited in the present application. For example, the second voltage VCC is 3.3V. In one example, the voltage stabilization circuit 200 converts 16V into 3.3V. The second voltage VCC can be used to supply power to the main control circuit 300, the zero-crossing detection circuit 500, the voltage detection circuit 600 and the display circuit 700.

[0083] The zero-crossing detection circuit 500 outputs a zero-crossing indication signal V_ZERO according to the received alternating voltage, and realizes the function of detecting the zero-crossing point of the alternating voltage.

[0084] The voltage detection circuit 600 obtains a grid acquisition voltage V_ADC by dividing the received alternating voltage.

[0085] The main control circuit 300 realizes the reading of the grid state according to the zero-crossing indication signal V_ZERO, outputs a control signal, and transmits the control signal to the driving circuit 400, so that the driving circuit 400 controls the relay to be in a closed state or an off state according to the control signal. It can also realize the acquisition of the grid voltage signal according to the grid acquisition voltage V_ADC, output the grid voltage and fault information, and drive the display circuit 700 to make the display circuit 700 display the grid voltage and the fault information. The grid voltage is the current alternating voltage of the grid, and the fault information is the overvoltage or undervoltage fault information.

[0086] In the embodiment of the present application, the level conversion is performed through the voltage reduction circuit and the voltage stabilizing circuit to provide power supply for the master control circuit, the driving circuit, the zero-crossing detection circuit, the voltage detection circuit and the display circuit, the zero-crossing detection circuit is used to realize the zero-crossing point detection of the alternating current signal, the master control circuit outputs the control signal according to the zero-crossing indication signal, the driving circuit controls the relay to be in the closed state or the off state according to the control signal, that is, the relay is tripped or closed at the zero-crossing point, which can improve the service life of the equipment, the voltage detection circuit is used to realize the collection of the power grid voltage signal, the master control circuit also outputs the power grid voltage and the fault information according to the collected power grid voltage, and drives the display circuit to make the display circuit display the power grid voltage and the fault information, thereby realizing the reading of the power grid voltage and the fault information.

[0087] In a possible embodiment, referring to Figure 2 , Figure 2 The voltage reduction circuit provided in the embodiment of the present application is shown in a structural schematic diagram as shown in Figure 2 The voltage reduction circuit 100 includes a first voltage-dependent resistor RV1, a second voltage-dependent resistor RV2, a third voltage-dependent resistor RV3, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a first voltage stabilizing diode ZD1, a first inductor L1, a second inductor L2, a first resistor R1 and a switching voltage stabilizer U1.

[0088] The first end of the second voltage-dependent resistor RV2 is electrically connected with a live input end L-IN, and the second end of the second voltage-dependent resistor RV2 is electrically connected with a neutral input end N-IN, the live input end L-IN and the neutral input end N-IN are used to connect the alternating current voltage.

[0089] The first end of the first voltage-dependent resistor RV1 is electrically connected with the first end of the second voltage-dependent resistor RV2, and the second end of the first voltage-dependent resistor RV1 is electrically connected with the first end of the third voltage-dependent resistor RV3, the positive electrode of the first diode D1 and the negative electrode of the third diode D3 respectively.

[0090] The second end of the third voltage-dependent resistor RV3 is electrically connected with the second end of the second voltage-dependent resistor RV2, the positive electrode of the second diode D2 and the negative electrode of the fourth diode D4 respectively.

[0091] The negative electrode of the first diode D1 is electrically connected with the negative electrode of the second diode D2, the first end of the first inductor L1 and the positive plate of the first capacitor C1 respectively.

[0092] The second end of the first inductor L1 is electrically connected with the positive plate of the second capacitor C2, the first end D1 of the switching voltage regulator U1, the second end D2 of the switching voltage regulator, the third end D3 of the switching voltage regulator, and the fourth end D4 of the switching voltage regulator respectively.

[0093] The fifth end VDD of the switching voltage regulator U1 is electrically connected with the negative pole of the sixth diode D6, the negative pole of the first voltage stabilizing diode ZD1, and the positive plate of the fourth capacitor C4 respectively, the sixth end FB of the switching voltage regulator U1 is electrically connected with the positive pole of the first voltage stabilizing diode ZD1 and the first end of the third capacitor C3 respectively, and the seventh end S1 of the switching voltage regulator U1 is electrically connected with the eighth end S2 of the switching voltage regulator U1, the second end of the third capacitor C3, the negative pole of the fifth diode D5, the negative plate of the fourth capacitor C4, and the first end of the second inductor L2 respectively.

[0094] The positive pole of the sixth diode D6 is electrically connected with the second end of the second inductor L2, the positive plate of the fifth capacitor C5, and the first end of the first resistor R1 respectively, and the first end of the first resistor R1 is used as an output end of the voltage reduction circuit 100 and is used for outputting the first voltage V1.

[0095] The positive pole of the third diode D3, the positive pole of the fourth diode D4, the negative plate of the first capacitor C1, the negative plate of the second capacitor C2, the positive pole of the fifth diode D5, the negative plate of the fifth capacitor C5, and the second end of the first resistor R1 are all grounded.

[0096] The switching voltage regulator U1 can be a power switching chip, for example, VIPER12A, to achieve the purpose of voltage stabilization. The voltage reduction circuit in the present application adopts a non-isolated voltage reduction circuit, which has stronger current output capability up to 400 mA, smaller size of corresponding magnetic elements (i.e. the first inductor L1 and the second inductor L2), higher energy efficiency, fewer components, and lower total material cost.

[0097] The voltage reduction circuit is surge protected by the first voltage-dependent resistor RV1, the second voltage-dependent resistor RV2, and the third voltage-dependent resistor RV3, and the protection circuit will not be damaged when the alternating voltage exceeds 380 V. The voltage reduction circuit can convert the alternating voltage of 220 V into direct current voltage after rectification and filtering, and then convert it into the first voltage V1 after voltage stabilization by the switching voltage regulator U1. In the present application, the first voltage V1 is +16 V.

[0098] In a possible embodiment, referring to Figure 3 , Figure 3 A structural schematic diagram of a voltage stabilization circuit provided in the embodiment of the present application is shown in Figure 3 As shown in the figure, the voltage stabilization circuit 200 can include a seventh diode D7, a second resistor R2, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, and a linear voltage regulator U2.

[0099] The positive pole of the seventh diode D7 is used for connecting the first voltage (+16V), the negative pole of the seventh diode D7 is electrically connected with the first end of the second resistor R2, the second end of the second resistor R2 is electrically connected with the positive plate of the sixth capacitor C6, the first end of the seventh capacitor C7 and the input end VIN of the linear voltage stabilizer U2 respectively.

[0100] The output end VOUT of the linear voltage stabilizer U2 is electrically connected with the positive plate of the eighth capacitor C8 and the first end of the ninth capacitor C9 respectively, and serves as the output end of the voltage stabilizing circuit 200, and is used for outputting the second voltage (+3.3V).

[0101] The negative plate of the sixth capacitor C6, the second end of the seventh capacitor C7, the ground end GND of the linear voltage stabilizer U2, the negative plate of the eighth capacitor C8 and the second end of the ninth capacitor C9 are grounded.

[0102] The linear voltage stabilizer U2 can be a LDO chip, for example, CS7533H, which converts the first voltage (+16V) into a stable second voltage (+3.3V). The seventh diode D7 can prevent the reverse connection of the power supply; the second resistor R2, the sixth capacitor C6 and the seventh capacitor C7 constitute a filter circuit, which filters out high-frequency and low-frequency noise in the first voltage (+16V); the eighth capacitor C8 and the ninth capacitor C9 further filter, to ensure the stability of the output second voltage (+3.3V), and provide a clean power supply for the subsequent circuit.

[0103] In a possible embodiment, referring to Figure 4 , Figure 4 A structure schematic diagram of a master control circuit provided in the embodiment of the application is shown in Figure 4 The master control circuit 300 can include a control chip U3, and the control signals include a first control signal drive1 and a second control signal drive2.

[0104] The fourth end of the control chip U3 is used for connecting a reset signal RESET, the seventh end of the control chip U3 is grounded, the eighth end of the control chip U3 is used for outputting a clock signal CLK, the ninth end of the control chip U3 is used for connecting the second voltage (+3.3V), and the tenth end of the control chip U3 is used for outputting or connecting a data signal DIO.

[0105] The twentieth end of the control chip U3 is used for connecting a grid acquisition voltage V_ADC, the nineteenth end of the control chip U3 is used for connecting a zero-crossing indication signal V_ZERO, the fourteenth end of the control chip U3 is used for outputting the first control signal drive1, and the thirteenth end of the control chip is used for outputting the second control signal drive2.

[0106] The control chip U3 is a core device of the over-voltage and under-voltage protection circuit, which can be a chip MSPS003F4 of Texas Instruments, and is used for realizing the collection of the grid voltage, the driving of the relay, the driving of the display circuit and the detection of the zero-crossing point.

[0107] The reset signal RESET is electrically connected with a reset circuit, which is a reset circuit commonly used in the prior art and will not be described herein.

[0108] In a possible embodiment, referring to Figure 5 , Figure 5 A structural schematic diagram of a driving circuit provided in the embodiment of the application is shown in Figure 5 The driving circuit 400 can include an eighth diode D8, a second zener diode ZD2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a tenth capacitor C10, a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5 and a sixth transistor Q6.

[0109] The first end of the eighth diode D8 is used for accessing a first voltage (+16V), and the second end of the eighth diode D8 is electrically connected with the positive plate of the tenth capacitor C10, the first end of the first transistor Q1 and the first end of the second transistor Q2 respectively.

[0110] The second end of the first transistor Q1 is electrically connected with the second end of the fourth transistor Q4, the first end of the second zener diode ZD2 and the first output end K1 of the driving circuit 400 respectively, and the control end of the first transistor Q1 is electrically connected with the first end of the fourth resistor R4.

[0111] The second end of the second transistor Q2 is electrically connected with the second end of the fifth transistor Q5, the second end of the second zener diode ZD2 and the second output end K2 of the driving circuit 400 respectively, and the control end of the second transistor Q2 is electrically connected with the first end of the third resistor R3.

[0112] The first end of the second zener diode ZD2 and the second end of the second zener diode ZD2 serve as output ends of the driving circuit 400, so as to control the relay to be in a closed state or an off state.

[0113] The second end of the third transistor Q3 is electrically connected with the second end of the third resistor R3, the first end of the third transistor Q3 is electrically connected with the control end of the fourth transistor Q4, and the first end of the fourth transistor Q4 is grounded.

[0114] The second end of the sixth transistor Q6 is electrically connected with the second end of the fourth resistor R4, and the first end of the sixth transistor Q6 is electrically connected with the control end of the fifth transistor Q5.

[0115] The control end of the third transistor Q3 is electrically connected with the first end of the sixth resistor R6, and the control end of the sixth transistor Q6 is electrically connected with the first end of the fifth resistor R5. The second end of the fifth resistor R5 is used for inputting the first control signal drive1, and the second end of the sixth resistor R6 is used for inputting the second control signal drive2.

[0116] The driving circuit 400 is an H-bridge driving circuit. The first output end K1 and the second output end K2 of the driving circuit 400 are electrically connected with the relay as the output end of the driving circuit 400. According to the first control signal drive1 and the second control signal drive2 output by the control chip U3, the relay is controlled to be in the closed state or the off state, that is, the opening and closing of the relay is controlled. For example, when the first control signal drive1 is 1 and the second control signal drive2 is 0, the relay is controlled to be in the closed state; when the first control signal drive1 is 0 and the second control signal drive2 is 1, the relay is controlled to be in the off state.

[0117] The second voltage stabilizing diode ZD2 is a bidirectional diode, which protects the relay and prevents impact.

[0118] In the present application, the first transistor Q1, the second transistor Q2, the third transistor Q3, the fourth transistor Q4, the fifth transistor Q5 and the sixth transistor Q6 can be bipolar transistors or field effect transistors, etc. For example, when the first transistor Q1, the second transistor Q2, the third transistor Q3, the fourth transistor Q4, the fifth transistor Q5 and the sixth transistor Q6 are bipolar transistors, the control end thereof refers to the base of the bipolar transistor, the first end can be the collector or the emitter of the bipolar transistor, and the corresponding second end can be the emitter or the collector of the bipolar transistor; when the first transistor Q1, the second transistor Q2, the third transistor Q3, the fourth transistor Q4, the fifth transistor Q5 and the sixth transistor Q6 are field effect transistors, the control end thereof refers to the gate of the field effect transistor, the first end can be the drain or the source of the field effect transistor, and the corresponding second end can be the source or the drain of the field effect transistor.

[0119] In a possible embodiment, referring to Figure 6 , Figure 6 A structural schematic diagram of a voltage detection circuit provided by the embodiment of the present application is shown in Figure 6 The voltage detection circuit 500 can include the ninth diode D9, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, the eleventh capacitor C11, the twelfth capacitor C12 and the operational amplifier U4.

[0120] The first end of the ninth diode D9 is electrically connected with the live input end L-IN, for accessing the alternating voltage, the second end of the ninth diode D9 is electrically connected with the first end of the seventh resistor R7, the second end of the seventh resistor R7 is electrically connected with the first end of the eighth resistor R8, and the second end of the eighth resistor R8 is electrically connected with the first end of the ninth resistor R9, the first end of the eleventh capacitor C11 and the non-inverting input end of the operational amplifier U4 respectively.

[0121] The non-inverting input end of the operational amplifier U4 is electrically connected with the first end of the tenth resistor R10, the second end of the tenth resistor R10 is electrically connected with the output end of the operational amplifier U4, and the output end of the operational amplifier U4 is used as the output end of the voltage detection circuit 500, and outputs the grid acquisition voltage V_ADC.

[0122] The power supply end of the operational amplifier U4 is electrically connected with the first end of the twelfth capacitor C12, for accessing the second voltage (+3.3V).

[0123] The second end of the ninth resistor R9, the second end of the eleventh capacitor C11, the second end of the twelfth capacitor C12 and the ground end of the operational amplifier U4 are all grounded.

[0124] The voltage detection circuit 500 accesses the alternating voltage through the half-wave rectification, and then performs voltage division through the resistor, transmits the voltage after voltage division to the non-inverting input end of the operational amplifier U4, obtains the grid acquisition voltage V_ADC through the voltage follower formed by the operational amplifier U4, and transmits the grid acquisition voltage V_ADC to the twentieth end of the control chip U3.

[0125] The specific working process of the voltage detection circuit 500 is as follows: the alternating voltage accessed through the live input end L-IN is half-wave rectified through the ninth diode D9, and then voltage division is performed through the seventh resistor R7 and the eighth resistor R8, and then high-frequency noise is filtered through the RC filter circuit formed by the ninth resistor R9 and the eleventh capacitor C11, and then transmitted to the non-inverting input end of the operational amplifier U4, the voltage follower formed by the operational amplifier U4, the output grid acquisition voltage V_ADC is equal to the voltage of the non-inverting input end of the operational amplifier U4, and the grid acquisition voltage V_ADC is transmitted to the twentieth end of the control chip U3 for voltage detection, thereby realizing the functions of collecting and measuring the grid voltage signal.

[0126] In a possible embodiment, referring to Figure 7 , Figure 7 The structure schematic diagram of the zero-crossing detection circuit provided in the embodiment of the application is shown in Figure 7 The zero-crossing detection circuit 600 can include the twelfth diode D10, the eleventh diode D11, the eleventh resistor R11, the twelfth resistor R12, the thirteenth capacitor C13 and the photoelectric coupler U5.

[0127] The first end of the twelfth diode D10 is electrically connected with the live input end L-IN, the second end of the twelfth diode D10 is electrically connected with the first end of the eleventh resistor R11, and the second end of the eleventh resistor R11 is electrically connected with the negative pole of the eleventh diode D11 and the first input end P1 of the photoelectric coupler U5 respectively.

[0128] The positive pole of the eleventh diode D11 is electrically connected with the neutral input end N-IN and the first output end T1 of the photoelectric coupler U5 respectively.

[0129] The second input end P2 of the photoelectric coupler U5 is electrically connected with the second end of the twelfth resistor R12 and the first end of the thirteenth capacitor C13 respectively, and serves as the output end of the zero-crossing detection circuit 600, and outputs the zero-crossing indication signal V_ZERO.

[0130] The first end of the twelfth resistor R12 is connected with the second voltage (+3.3V), and the second end of the thirteenth capacitor C13 and the second output end T2 of the photoelectric coupler U5 are grounded.

[0131] The zero-crossing detection circuit realizes zero-crossing point detection on the alternating current signal, controls the relay to operate in the opening or closing state at the zero-crossing point, is not easy to appear larger breaking arc and noise, prevents the occurrence of arc phenomenon, and can improve the service life of the equipment.

[0132] The twelfth diode D10 has the rectifying effect, and can rectify the alternating voltage. The eleventh resistor R11 is used for current limiting, and can prevent damage to the subsequent circuit when the current is too large. The photoelectric coupler U5 realizes electrical isolation between the input signal and the output signal, enhances the anti-interference ability of the circuit, and simultaneously transmits the output zero-crossing indication signal V_ZERO to the nineteenth end of the control chip U3.

[0133] The twelfth resistor R12 and the thirteenth capacitor C13 play a role in filtering and stabilizing the output signal, and at the same time, the thirteenth capacitor C13 can filter out high-frequency interference, so that the output zero-crossing indication signal V_ZERO is more stable and clean. The zero-crossing indication signal V_ZERO can indicate the zero-crossing point of the alternating current signal, so that the control chip U3 can output the first control signal drive1 and the second control signal drive2 according to the zero-crossing indication signal V_ZERO, control the relay to be in the closed state or the off state, that is, control the opening and closing of the relay.

[0134] The working principle of the zero-crossing detection circuit is as follows: During the positive and negative half-cycles of the AC voltage, the optocoupler U5 is turned on, and the second input terminal P2 of the optocoupler U5 is grounded. At this time, the zero-crossing indicator signal V_ZERO is low. At the instant the AC voltage crosses zero, since the voltage is close to zero, the optocoupler U5 is turned off, and the second input terminal P2 of the optocoupler U5 is pulled up to +3.3V by the twelfth resistor R12. At this time, the zero-crossing indicator signal V_ZERO is high.

[0135] The nineteenth terminal of the control chip U3 is connected to the zero-crossing indicator signal V_ZERO. As the AC voltage changes periodically, the zero-crossing indicator signal V_ZERO switches between high and low levels. By detecting this level transition, the control chip U3 can determine the zero-crossing point of the AC signal, and thus output the first control signal drive1 and the second control signal drive2 to control the relay to open the contact at or near the zero-crossing point and cut off the circuit.

[0136] In one possible embodiment, see Figure 8 , Figure 8 This is a schematic diagram of a display circuit provided in an embodiment of this application, such as... Figure 8 As shown, the display circuit 700 includes: a display screen LCD, a display driver U6, a thirteenth resistor R13, a fourteenth resistor R14, and a fourteenth capacitor C14.

[0137] The first terminal SEG7 of the display driver U6 is electrically connected to the thirty-seventh terminal S7 of the LCD display. The second terminal SEG6 of the display driver U6 is electrically connected to the thirty-eighth terminal S6 of the LCD display. The third terminal SEG5 of the display driver U6 is electrically connected to the thirty-ninth terminal S5 of the LCD display. The fourth terminal SEG4 of the display driver U6 is electrically connected to the forty-first terminal S4 of the LCD display. The fifth terminal SEG3 of the display driver U6 is electrically connected to the thirty-first terminal S3 of the LCD display. The sixth terminal SEG2 of the display driver U6 is electrically connected to the thirty-second terminal S2 of the LCD display. The seventh terminal SEG1 of the display driver U6 is electrically connected to the thirty-third terminal S1 of the LCD display. The eighth terminal SEG0 of the display driver U6 is electrically connected to the thirty-fourth terminal S0 of the LCD display.

[0138] The eleventh end WR# of the display driver U6 accesses the clock signal CLK, the twelfth end DATA of the display driver U6 accesses the data signal DIO, the thirteenth end VSS of the display driver U6 is grounded, the sixteenth end VLCD of the display driver U6 is electrically connected with the first end of the thirteenth resistor R13, the seventeenth end VDD of the display driver U6 accesses the second voltage VCC, the eighteenth end IRQ# of the display driver U6 is electrically connected with the first end of the fourteenth resistor R14, the second end of the thirteenth resistor R13 is electrically connected with the second end of the fourteenth resistor R14 and the positive plate of the fourteenth capacitor C14 respectively, and is used for accessing the second voltage VCC, and the negative plate of the fourteenth capacitor C14 is grounded.

[0139] The twenty-first end COM0 of the display driver U6 is electrically connected with the twenty-eighth end COM0# of the display screen LCD, the twenty-second end COM1 of the display driver U6 is electrically connected with the twenty-seventh end COM1# of the display screen LCD, the twenty-third end COM2 of the display driver U6 is electrically connected with the twenty-sixth end COM2# of the display screen LCD, and the twenty-fourth end COM3 of the display driver U6 is electrically connected with the twenty-fifth end COM3# of the display screen LCD.

[0140] The twenty-eighth end SEG28 of the display driver U6 is electrically connected with the sixteenth end S28 of the display screen LCD, the twenty-ninth end SEG27 of the display driver U6 is electrically connected with the seventeenth end S27 of the display screen LCD, the thirtieth end SEG26 of the display driver U6 is electrically connected with the eighteenth end S26 of the display screen LCD, the thirty-first end SEG25 of the display driver U6 is electrically connected with the nineteenth end S25 of the display screen LCD, the thirty-second end SEG24 of the display driver U6 is electrically connected with the twentieth end S24 of the display screen LCD, the thirty-third end SEG23 of the display driver U6 is electrically connected with the first end S23 of the display screen LCD, the thirty-fourth end SEG22 of the display driver U6 is electrically connected with the second end S22 of the display screen LCD, the thirty-fifth end SEG21 of the display driver U6 is electrically connected with the third end S21 of the display screen, the thirty-sixth end SEG20 of the display driver U6 is electrically connected with the fourth end S20 of the display screen LCD, the thirty-seventh end SEG19 of the display driver U6 is electrically connected with the fifth end S19 of the display screen LCD, the thirty-eighth end SEG18 of the display driver U6 is electrically connected with the sixth end S18 of the display screen LCD, the thirty-ninth end SEG17 of the display driver U6 is electrically connected with the seventh end S17 of the display screen LCD, and the fortieth end SEG16 of the display driver U6 is electrically connected with the eighth end S16 of the display screen LCD.

[0141] The forty-first end SEG15 of the display driver U6 is electrically connected with the twenty-first end S15 of the display screen LCD, the forty-second end SEG14 of the display driver U6 is electrically connected with the twenty-second end S14 of the display screen LCD, the forty-third end SEG13 of the display driver U6 is electrically connected with the twenty-third end S13 of the display screen LCD, the forty-fourth end SEG12 of the display driver U6 is electrically connected with the twenty-fourth end S12 of the display screen LCD, the forty-fifth end SEG11 of the display driver U6 is electrically connected with the forty-fourth end S11 of the display screen LCD, the forty-sixth end SEG10 of the display driver U6 is electrically connected with the forty-second end S10 of the display screen LCD, the forty-seventh end SEG9 of the display driver U6 is electrically connected with the thirty-fifth end S9 of the display screen LCD, and the forty-eighth end SEG8 of the display driver U6 is electrically connected with the thirty-sixth end S8 of the display screen LCD.

[0142] The display driver U6 is connected with the clock signal CLK and the data signal DIO output by the control chip U3, and drives the display driver U6 through the control chip U3, so as to drive the display screen LCD to display. In an example, the display driver U6 can be an HT162 chip.

[0143] The HT162 chip is a liquid crystal display driving chip, which includes 48 pins, including segment driving pins SEG0-SEG31, common end pins COM0-COM4, control pins WR#, CS, CLC, etc. The pins of the HT162 chip are electrically connected with the corresponding pins of the display screen LCD, so as to drive the display screen to display. For example, the segment driving pins SEG0-SEG31 of the HT162 chip are electrically connected with the corresponding segment driving pins of the display screen LCD, and the common end pins COM0-COM4 of the HT162 chip are electrically connected with the corresponding common end pins of the display screen LCD.

[0144] In addition, the circuit composed of the thirteenth resistor R13, the fourteenth resistor R14 and the fourteenth capacitor C14 is used for filtering or oscillation control of the second voltage VCC.

[0145] The embodiment of the present application further provides a substrate, which comprises the over-voltage and under-voltage protection circuit.

[0146] The embodiment of the present application further provides a self-recovery over-voltage and under-voltage protector, which comprises the substrate and a relay.

[0147] The relay is arranged outside the substrate and is electrically connected with the substrate.

[0148] Finally, it should be noted that the above embodiments are merely specific embodiments of the present application, and the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An over- and under-voltage protection circuit, characterized in that The over-voltage and under-voltage protection circuit comprises a voltage reduction circuit, a voltage stabilizing circuit, a main control circuit, a driving circuit, a zero-crossing detection circuit, a voltage detection circuit and a display circuit; The voltage reduction circuit is electrically connected with the voltage stabilizing circuit and the driving circuit respectively, and the main control circuit is electrically connected with the voltage stabilizing circuit, the driving circuit, the zero-crossing detection circuit, the voltage detection circuit and the display circuit respectively; The voltage reduction circuit is arranged to receive an alternating voltage and convert the alternating voltage into a first voltage, and the first voltage is used to power the driving circuit; The voltage stabilizing circuit is arranged to receive the first voltage and convert the first voltage into a second voltage, and the second voltage is used to power the main control circuit, the zero-crossing detection circuit, the voltage detection circuit and the display circuit; The zero-crossing detection circuit is arranged to receive the alternating voltage and output a zero-crossing indication signal according to the alternating voltage; The voltage detection circuit is arranged to receive the alternating voltage and divide the alternating voltage to obtain a power grid acquisition voltage; The main control circuit is arranged to output a control signal according to the zero-crossing indication signal and transmit the control signal to the driving circuit, and output a power grid voltage and fault information according to the power grid acquisition voltage and drive the display circuit to display the power grid voltage and the fault information; The driving circuit is arranged to control a relay to be in a closed state or an off state according to the control signal.

2. The over / under voltage protection circuit according to claim 1, characterized by The voltage reduction circuit comprises a first voltage-dependent resistor, a second voltage-dependent resistor, a third voltage-dependent resistor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a first voltage stabilizing diode, a first inductor, a second inductor, a first resistor and a switching voltage stabilizer; A first end of the second voltage-dependent resistor is electrically connected with a live input end, and a second end of the second voltage-dependent resistor is electrically connected with a zero input end, and the live input end and the zero input end are used to input the alternating voltage; A first end of the first voltage-dependent resistor is electrically connected with a first end of the second voltage-dependent resistor, and a second end of the first voltage-dependent resistor is electrically connected with a first end of the third voltage-dependent resistor, a positive electrode of the first diode and a negative electrode of the third diode respectively; A second end of the third voltage-dependent resistor is electrically connected with a second end of the second voltage-dependent resistor, a positive electrode of the second diode and a negative electrode of the fourth diode respectively; A negative electrode of the first diode is electrically connected with a negative electrode of the second diode, a first end of the first inductor and a positive electrode plate of the first capacitor respectively; A second end of the first inductor is electrically connected with a positive electrode plate of the second capacitor, a first end of the switching voltage stabilizer, a second end of the switching voltage stabilizer, a third end of the switching voltage stabilizer and a fourth end of the switching voltage stabilizer; The fifth end of the switching voltage stabilizer is electrically connected with the negative pole of the sixth diode, the negative pole of the first voltage stabilizing diode and the positive pole plate of the fourth capacitor respectively, the sixth end of the switching voltage stabilizer is electrically connected with the positive pole of the first voltage stabilizing diode and the first end of the third capacitor respectively, and the seventh end of the switching voltage stabilizer is electrically connected with the eighth end of the switching voltage stabilizer, the second end of the third capacitor, the negative pole of the fifth diode, the negative pole plate of the fourth capacitor and the first end of the second inductor respectively; The positive pole of the sixth diode is electrically connected with the second end of the second inductor, the positive pole plate of the fifth capacitor and the first end of the first resistor respectively, and the first end of the first resistor is used as the output end of the voltage reduction circuit and is used for outputting the first voltage; The positive pole of the third diode, the positive pole of the fourth diode, the negative pole plate of the first capacitor, the negative pole plate of the second capacitor, the positive pole of the fifth diode, the negative pole plate of the fifth capacitor and the second end of the first resistor are grounded.

3. The overvoltage and undervoltage protection circuit of claim 1, wherein, The voltage stabilizing circuit comprises a seventh diode, a second resistor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor and a linear voltage stabilizer; The positive pole of the seventh diode is used for accessing the first voltage, the negative pole of the seventh diode is electrically connected with the first end of the second resistor, the second end of the second resistor is electrically connected with the positive pole plate of the sixth capacitor, the first end of the seventh capacitor and the input end of the linear voltage stabilizer respectively; The output end of the linear voltage stabilizer is electrically connected with the positive pole plate of the eighth capacitor and the first end of the ninth capacitor respectively, and is used as the output end of the voltage stabilizing circuit and is used for outputting the second voltage; The negative pole plate of the sixth capacitor, the second end of the seventh capacitor, the grounding end of the linear voltage stabilizer, the negative pole plate of the eighth capacitor and the second end of the ninth capacitor are grounded.

4. The overvoltage and undervoltage protection circuit of claim 1, wherein, The main control circuit comprises a control chip, and the control signal comprises a first control signal and a second control signal; The fourth end of the control chip is used for accessing a reset signal, the seventh end of the control chip is grounded, the eighth end of the control chip is used for outputting a clock signal, the ninth end of the control chip is used for accessing the second voltage, and the tenth end of the control chip is used for outputting or accessing a data signal; The twentieth end of the control chip is used for accessing the grid acquisition voltage, the nineteenth end of the control chip is used for accessing the zero-crossing indication signal, the fourteenth end of the control chip is used for outputting the first control signal, and the thirteenth end of the control chip is used for outputting the second control signal.

5. The overvoltage and undervoltage protection circuit of claim 4, wherein, The driving circuit comprises an eighth diode, a second voltage stabilizing diode, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a tenth capacitor, a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor and a sixth transistor; The first end of the eighth diode is used for accessing the first voltage, and the second end of the eighth diode is electrically connected with the positive pole plate of the tenth capacitor, the first end of the first transistor and the first end of the second transistor respectively; The second end of the first transistor is electrically connected with the second end of the fourth transistor, the first end of the second voltage stabilizing diode and the first output end of the driving circuit respectively, and the control end of the first transistor is electrically connected with the first end of the fourth resistor; The second end of the second transistor is electrically connected with the second end of the fifth transistor, the second end of the second voltage stabilizing diode and the second output end of the driving circuit respectively, and the control end of the second transistor is electrically connected with the first end of the third resistor; The first end of the second voltage stabilizing diode is electrically connected with the second end of the second voltage stabilizing diode as the output end of the driving circuit, so as to control the relay to be in the closed state or the off state; The second end of the third transistor is electrically connected with the second end of the third resistor, the first end of the third transistor is electrically connected with the control end of the fourth transistor, and the first end of the fourth transistor is grounded with the first end of the fifth transistor; The second end of the sixth transistor is electrically connected with the second end of the fourth resistor, and the first end of the sixth transistor is electrically connected with the control end of the fifth transistor; The control end of the third transistor is electrically connected with the first end of the sixth resistor, the control end of the sixth transistor is electrically connected with the first end of the fifth resistor, the second end of the fifth resistor is used for inputting the first control signal, and the second end of the sixth resistor is used for inputting the second control signal.

6. The overvoltage and undervoltage protection circuit of claim 4, wherein, The voltage detection circuit comprises a ninth diode, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh capacitor, a twelfth capacitor and an operational amplifier; The first end of the ninth diode is electrically connected with the live input end for inputting the alternating voltage, the second end of the ninth diode is electrically connected with the first end of the seventh resistor, the second end of the seventh resistor is electrically connected with the first end of the eighth resistor, and the second end of the eighth resistor is electrically connected with the first end of the ninth resistor, the first end of the eleventh capacitor and the non-inverting input end of the operational amplifier respectively; The inverting input end of the operational amplifier is electrically connected with the first end of the tenth resistor, the second end of the tenth resistor is electrically connected with the output end of the operational amplifier and is used as the output end of the voltage detection circuit, and outputs the grid acquisition voltage; The power supply end of the operational amplifier is electrically connected with the first end of the twelfth capacitor for inputting the second voltage; The second end of the ninth resistor, the second end of the eleventh capacitor, the second end of the twelfth capacitor and the ground end of the operational amplifier are all grounded.

7. The overvoltage and undervoltage protection circuit of claim 4, wherein, The zero-crossing detection circuit comprises a twelfth diode, an eleventh diode, an eleventh resistor, a twelfth resistor, a thirteenth capacitor and a photoelectric coupler; The first end of the twelfth diode is electrically connected with the live input end, and the second end of the twelfth diode is electrically connected with the first end of the eleventh resistor, the second end of the eleventh resistor is electrically connected with the negative electrode of the eleventh diode and the first input end of the photoelectric coupler respectively; The positive electrode of the eleventh diode is electrically connected with the zero input end and the first output end of the photoelectric coupler respectively. The second input end of the optoelectrical coupler is electrically connected with the second end of the twelfth resistor and the first end of the thirteenth capacitor respectively, and serves as an output end of the zero-cross detection circuit, and outputs the zero-cross indication signal; The first end of the twelfth resistor is connected with the second voltage, and the second end of the thirteenth capacitor and the second output end of the optoelectrical coupler are grounded.

8. The overvoltage and undervoltage protection circuit of claim 4, wherein, The display circuit comprises a display screen, a display driver, a thirteenth resistor, a fourteenth resistor and a fourteenth capacitor; The first end of the display driver is electrically connected with the thirty-seventh end of the display screen, the second end of the display driver is electrically connected with the thirty-eighth end of the display screen, the third end of the display driver is electrically connected with the thirty-ninth end of the display screen, the fourth end of the display driver is electrically connected with the forty-first end of the display screen, the fifth end of the display driver is electrically connected with the thirty-first end of the display screen, the sixth end of the display driver is electrically connected with the thirty-second end of the display screen, the seventh end of the display driver is electrically connected with the thirty-third end of the display screen, and the eighth end of the display driver is electrically connected with the thirty-fourth end of the display screen; The eleventh end of the display driver is connected with the clock signal, the twelfth end of the display driver is connected with the data signal, the thirteenth end of the display driver is grounded, the sixteenth end of the display driver is electrically connected with the first end of the thirteenth resistor, the seventeenth end of the display driver is connected with the second voltage, the eighteenth end of the display driver is electrically connected with the first end of the fourteenth resistor, the second end of the thirteenth resistor is electrically connected with the second end of the fourteenth resistor and the positive plate of the fourteenth capacitor respectively, and is used for connecting with the second voltage, and the negative plate of the fourteenth capacitor is grounded; The twenty-first end of the display driver is electrically connected with the twenty-eighth end of the display screen, the twenty-second end of the display driver is electrically connected with the twenty-seventh end of the display screen, the twenty-third end of the display driver is electrically connected with the twenty-sixth end of the display screen, and the twenty-fourth end of the display driver is electrically connected with the twenty-fifth end of the display screen. The twenty-eighth end of the display driver is electrically connected with the sixteenth end of the display screen, the twenty-ninth end of the display driver is electrically connected with the seventeenth end of the display screen, the thirtieth end of the display driver is electrically connected with the eighteenth end of the display screen, the thirty-first end of the display driver is electrically connected with the nineteenth end of the display screen, the thirty-second end of the display driver is electrically connected with the twentieth end of the display screen, the thirty-third end of the display driver is electrically connected with the first end of the display screen, the thirty-fourth end of the display driver is electrically connected with the second end of the display screen, the thirty-fifth end of the display driver is electrically connected with the third end of the display screen, the thirty-sixth end of the display driver is electrically connected with the fourth end of the display screen, the thirty-seventh end of the display driver is electrically connected with the fifth end of the display screen, the thirty-eighth end of the display driver is electrically connected with the sixth end of the display screen, the thirty-ninth end of the display driver is electrically connected with the seventh end of the display screen, and the fortieth end of the display driver is electrically connected with the eighth end of the display screen. The forty-first end of the display driver is electrically connected with the twenty-first end of the display screen, the forty-second end of the display driver is electrically connected with the twenty-second end of the display screen, the forty-third end of the display driver is electrically connected with the twenty-third end of the display screen, the forty-fourth end of the display driver is electrically connected with the twenty-fourth end of the display screen, the forty-fifth end of the display driver is electrically connected with the forty-fourth end of the display screen, the forty-sixth end of the display driver is electrically connected with the forty-second end of the display screen, the forty-seventh end of the display driver is electrically connected with the thirty-fifth end of the display screen, and the forty-eighth end of the display driver is electrically connected with the thirty-sixth end of the display screen.

9. A substrate, characterized by, Comprising: The overvoltage and undervoltage protection circuit of any one of claims 1-8.

10. A self-resetting over / under-voltage protector, characterized by Comprising: The substrate and relay of claim 9.

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