A protection circuit, a substrate and a circuit breaker

Abstract

The application provides a protection circuit, a substrate and a circuit breaker, and relates to the technical field of circuit breaker control. The circuit comprises a voltage acquisition circuit, a frequency acquisition circuit, a main control circuit and a motor driving circuit. The voltage acquisition circuit samples the voltage amplitude of phase voltage to obtain an amplitude voltage. The frequency acquisition circuit obtains a phase voltage frequency according to the amplitude voltage and a reference voltage. The main control circuit is used for comparing the amplitude voltage with a voltage protection threshold to obtain a first comparison result, comparing the phase voltage frequency with a frequency protection threshold to obtain a second comparison result, and outputting a driving signal according to the first comparison result and the second comparison result. The motor driving circuit drives a motor to act according to the driving signal, so as to control the circuit breaker to perform opening or closing operation. The amplitude and frequency of the power grid are detected, and the circuit breaker is controlled to perform opening or closing operation according to the amplitude voltage and the phase voltage frequency, so as to provide corresponding protection function.

Description

Technical Field

[0001] This application relates to the field of circuit breaker control technology, and in particular to a protection circuit, a substrate, and a circuit breaker. Background Technology

[0002] Traditional energy sources such as coal and natural gas lead to increased greenhouse gas emissions during combustion, exacerbating climate change. To improve the environment and achieve carbon peaking by 2030 and carbon neutrality by 2060, the development of green energy has been strongly promoted in recent years. Photovoltaic power generation, due to its abundant resources, mature technology, and low cost, has become a major choice for developing green energy. Grid-connected photovoltaic power generation is a crucial technology in the photovoltaic power generation field.

[0003] Grid-connected photovoltaic (PV) power generation refers to connecting a solar photovoltaic (PV) power generation system to the conventional power grid to jointly supply electricity. When there is sunlight, the inverter converts the direct current (DC) generated by the PV system into sinusoidal alternating current (AC). This AC power can be directly supplied to AC loads, and any remaining energy can be fed into the grid, or all generated energy can be directly integrated into the grid. When there is no sunlight, all power to the loads is supplied by the grid. Grid-connected PV circuit breakers play a crucial role in PV grid-connected power generation; they connect between the PV side and the grid side to control the switching between the two.

[0004] A fundamental requirement for grid-connected photovoltaic (PV) power generation systems is that the frequency and phase of the sinusoidal alternating current output by the inverter on the PV side are identical to the frequency and phase of the alternating current on the grid side. Grid-connected PV systems play a crucial role in the power quality of the grid, especially since the grid frequency is a core indicator for measuring the balance between power generation and consumption, and must be strictly controlled within a certain range during normal operation. When the grid frequency on the PV side exceeds the allowable range—for example, if the grid frequency on the PV side is less than or equal to 49Hz or greater than or equal to 50.5Hz—the power supply system on the PV side should be quickly disconnected to reduce voltage surges. Furthermore, grid-connected PV systems should also avoid the risk of islanding effects; for example, if the grid experiences a power outage, the power supply system on the PV side may continue to supply power to a localized area of ​​the grid, threatening the safety of maintenance personnel.

[0005] During power grid faults, the grid frequency often changes abruptly. Detecting the frequency and implementing protection measures based on it can serve as a means of preventing islanding effects. Voltage amplitude exceeding permissible ranges in the grid can also lead to faults. Therefore, how to detect grid faults and provide corresponding protection functions is an important issue that needs to be addressed. Utility Model Content

[0006] This application provides a protection circuit, a substrate, and a circuit breaker to detect the power grid and provide corresponding protection functions.

[0007] In a first aspect, this application provides a protection circuit, which includes: a voltage acquisition circuit, a frequency acquisition circuit, a main control circuit, and a motor drive circuit; The input terminal of the voltage acquisition circuit is used to connect to the phase voltage, and the output terminal of the voltage acquisition circuit is electrically connected to the first input terminal of the frequency acquisition circuit and the main control circuit, respectively; the second input terminal of the frequency acquisition circuit is used to connect to the reference voltage, and the output terminal of the frequency acquisition circuit is electrically connected to the main control circuit; the main control circuit is electrically connected to the motor drive circuit. The voltage acquisition circuit is used to sample the voltage amplitude of the phase voltage to obtain the amplitude voltage; The frequency acquisition circuit is used to obtain the phase voltage frequency based on the amplitude voltage and the reference voltage; The main control circuit is used to compare the amplitude voltage with the voltage protection threshold to obtain a first comparison result; compare the phase voltage frequency with the frequency protection threshold to obtain a second comparison result; and output a drive signal according to the first comparison result and the second comparison result. The motor drive circuit is used to drive the motor to operate according to the drive signal, so as to control the circuit breaker to perform opening or closing operations.

[0008] In one possible design, the voltage acquisition circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a clamping diode, and a first capacitor; The first end of the first resistor is electrically connected to the input terminal of the voltage acquisition circuit, the second end of the first resistor is electrically connected to the first end of the second resistor, the second end of the second resistor is electrically connected to the first end of the third resistor, and the second end of the third resistor is electrically connected to the second end of the fourth resistor, the first end of the fifth resistor, the clamping terminal of the clamping diode, the first end of the first capacitor, and the output terminal of the voltage acquisition circuit, respectively, for outputting the amplitude voltage; The cathode of the clamping diode is electrically connected to the first end of the fourth resistor for use in applying the operating voltage. The anode of the clamping diode, the second terminal of the first capacitor, and the second terminal of the fifth resistor are all grounded.

[0009] In one possible design, the frequency acquisition circuit includes a reference voltage generation circuit and a comparison circuit; The reference voltage generation circuit is used to generate the reference voltage; The comparison circuit is used to compare the amplitude voltage with the reference voltage to obtain the phase voltage frequency.

[0010] In one possible design, the reference voltage generation circuit includes: a sixth resistor, a seventh resistor, and a second capacitor; The first end of the sixth resistor is used to connect to the working voltage, and the second end of the sixth resistor is electrically connected to the first end of the seventh resistor, the first end of the second capacitor, and the output end of the reference voltage generation circuit, respectively, for outputting the reference voltage. The second terminal of the seventh resistor and the second terminal of the second capacitor are both grounded.

[0011] In one possible design, the comparison circuit includes: a comparator, an eighth resistor, a ninth resistor, a tenth resistor, and a third capacitor; The first end of the eighth resistor is electrically connected to the first input terminal of the frequency acquisition circuit, and the second end of the eighth resistor is electrically connected to the positive input terminal of the comparator and the first end of the ninth resistor, respectively. The inverting input terminal of the comparator is electrically connected to the output terminal of the reference voltage generation circuit, and serves as the second input terminal of the frequency acquisition circuit for connecting the reference voltage. The second end of the ninth resistor is electrically connected to the output end of the comparator, the second end of the tenth resistor, and the first end of the third capacitor, and serves as the output end of the frequency acquisition circuit for outputting the phase voltage frequency. The first end of the tenth resistor is used to connect to the operating voltage, and the second end of the third capacitor is grounded.

[0012] In one possible design, the drive signal includes a first drive signal and a second drive signal, and the motor drive circuit includes an eleventh resistor, a fourth capacitor, a fifth capacitor, a sixth capacitor, and a motor drive chip. The second terminal of the motor driver chip is connected to the first drive signal, the third terminal of the motor driver chip is connected to the second drive signal, the fourth terminal of the motor driver chip is electrically connected to the first terminal of the eleventh resistor, and the second terminal of the eleventh resistor is grounded. The fifth terminal of the motor drive chip is grounded; The sixth terminal of the motor driver chip is electrically connected to the first terminal of the fourth capacitor and the first input terminal of the motor, respectively. The seventh terminal of the motor driver chip is electrically connected to the second terminal of the fourth capacitor and the second input terminal of the motor, respectively. The eighth terminal of the motor drive chip is electrically connected to the first terminal of the fifth capacitor and the first terminal of the sixth capacitor, respectively, and is used to receive the drive voltage. The second terminal of the fifth capacitor and the second terminal of the sixth capacitor are both grounded.

[0013] In one possible design, the protection circuit further includes: a display circuit and a power supply circuit; The display circuit is electrically connected to the main control circuit, and the power supply circuit is electrically connected to the voltage acquisition circuit, the frequency acquisition circuit, the main control circuit, the motor drive circuit, and the display circuit, respectively. The display circuit is used to display the operating status of the circuit breaker according to the display signal; The power supply circuit is used to output the operating voltage and the driving voltage.

[0014] In one possible design, the display signal includes a first display signal and a second display signal; the display circuit includes: a twelfth resistor, a thirteenth resistor, a first light-emitting diode, and a second light-emitting diode; The first end of the twelfth resistor is electrically connected to the main control circuit and is used to receive the first display signal; the second end of the twelfth resistor is electrically connected to the cathode of the first light-emitting diode. The first end of the thirteenth resistor is electrically connected to the main control circuit for receiving the second display signal, and the second end of the thirteenth resistor is electrically connected to the cathode of the second light-emitting diode. The anode of the first light-emitting diode is electrically connected to the anode of the second light-emitting diode and is connected to the operating voltage.

[0015] In a second aspect, this application provides a substrate including: the protection circuit as described in the first aspect.

[0016] Thirdly, this application provides a circuit breaker, comprising: a substrate as described in the second aspect.

[0017] The beneficial effects of the embodiments of this application are as follows: In this embodiment, a voltage acquisition circuit samples the phase voltage amplitude to obtain the amplitude voltage, thereby detecting the grid voltage. A frequency acquisition circuit obtains the phase voltage frequency based on the amplitude voltage and a reference voltage, thereby detecting the grid frequency. The main control circuit outputs a drive signal based on the amplitude voltage and the phase voltage frequency, comparing the amplitude voltage with a voltage protection threshold to obtain a first comparison result; comparing the phase voltage frequency with a frequency protection threshold to obtain a second comparison result; and outputting a drive signal based on the first and second comparison results. Finally, a motor drive circuit drives the motor to operate according to the drive signal, thereby controlling the circuit breaker to perform opening or closing operations. By detecting the grid amplitude and frequency, and based on the comparison results of the amplitude voltage and the voltage protection threshold, as well as the comparison results of the phase voltage frequency and the frequency protection threshold, the circuit breaker is controlled to perform opening or closing operations, providing corresponding protection functions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0019] Figure 1 This is a schematic diagram of the circuit structure of a protection circuit provided in an embodiment of this application; Figure 2 A schematic diagram of the circuit structure of a voltage acquisition circuit provided in an embodiment of this application; Figure 3 A waveform diagram of phase voltage and amplitude voltage provided for an embodiment of this application; Figure 4 A schematic diagram of the circuit structure of a frequency acquisition circuit provided in an embodiment of this application; Figure 5 A waveform diagram of a frequency acquisition circuit provided in an embodiment of this application; Figure 6 A schematic diagram of a periodic waveform of a phase voltage frequency provided in an embodiment of this application; Figure 7 A schematic diagram of the circuit structure of a motor drive circuit provided in an embodiment of this application; Figure 8 A schematic diagram of the circuit structure of another protection circuit provided in an embodiment of this application; Figure 9 This is a schematic diagram of the circuit structure of a display circuit provided in an embodiment of this application. Detailed Implementation

[0020] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] The terms “center,” “longitudinal,” “lateral,” “up,” “down,” “left,” “right,” “front,” and “rear,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application 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 this application.

[0022] The terms "connected" and "connected" should be interpreted broadly. For example, in circuit structures, "connected" or "connected" can refer not only to physical connections but also to electrical or signal connections. This could be a direct connection (physical connection) or an indirect connection via at least one intermediate component, as long as the circuit is connected. It could also refer to the internal connection between two components. Similarly, a signal connection can refer to a connection via a circuit or a medium, such as radio waves. Those skilled in the art will understand the specific meaning of these terms in this application based on the specific circumstances.

[0023] To enable power grid monitoring and provide corresponding protection functions, this application provides a protection circuit, see [link to relevant documentation]. Figure 1 , Figure 1 A circuit structure diagram of a protection circuit provided in an embodiment of this application is shown below. Figure 1 As shown, the protection circuit 1000 may include: a voltage acquisition circuit 100, a frequency acquisition circuit 200, a main control circuit 300, and a motor drive circuit 400.

[0024] The input terminal VIN of the voltage acquisition circuit 100 is used to connect the phase voltage. The output terminal P1 of the voltage acquisition circuit 100 is electrically connected to the first input terminal P2 of the frequency acquisition circuit 200 and the main control circuit 300, respectively. The second input terminal P3 of the frequency acquisition circuit 200 is used to connect the reference voltage VREF. The output terminal P4 of the frequency acquisition circuit 200 is electrically connected to the main control circuit 300. The main control circuit 300 is electrically connected to the motor drive circuit 400.

[0025] The voltage acquisition circuit 100 is used to sample the voltage amplitude of the phase voltage to obtain the amplitude voltage VA.

[0026] The frequency acquisition circuit 200 is used to obtain the phase voltage frequency FRE_A based on the amplitude voltage VA and the reference voltage VREF.

[0027] The main control circuit 300 is used to compare the amplitude voltage VA with the voltage protection threshold to obtain a first comparison result; compare the phase voltage frequency FRE_A with the frequency protection threshold to obtain a second comparison result; and output a drive signal based on the first comparison result and the second comparison result.

[0028] The motor drive circuit 400 is used to drive the motor to operate according to the drive signal, so as to control the circuit breaker to perform opening or closing operations.

[0029] The protection circuit in this application is applied to a photovoltaic grid-connected circuit breaker. The photovoltaic grid-connected circuit breaker is usually connected between the photovoltaic side and the grid side. The circuit breaker drives the motor to operate, and based on the linkage device electrically connected to the motor, it controls the circuit breaker to perform opening or closing operations, thereby realizing the protection function.

[0030] The grid-side busbar includes phase A, phase B, phase C, and neutral N. For mains power, the AC voltage between phase A and phase B is 380VAC, the AC voltage between phase A and phase C is 380VAC, and the AC voltage between phase B and phase C is 380VAC. The AC voltage between phase A and neutral N is 220VAC, the AC voltage between phase B and neutral N is 220VAC, and the AC voltage between phase C and neutral N is 220VAC. Phase voltage refers to the voltage between phase A and neutral N (phase A voltage), or between phase B and neutral N (phase B voltage), or between phase C and neutral N (phase C voltage). The voltage acquisition circuit samples the amplitude of the phase voltage to obtain the amplitude voltage. The phase voltage can be selected from phase A, phase B, or phase C voltage.

[0031] The frequency acquisition circuit 200 compares the amplitude voltage VA output by the voltage acquisition circuit 100 with the reference voltage VREF to obtain the phase voltage frequency FRE_A. The amplitude and frequency of the phase voltage (i.e., amplitude voltage VA and phase voltage frequency FRE_A) can be obtained through the voltage acquisition circuit and the frequency acquisition circuit, and the amplitude voltage VA and phase voltage frequency FRE_A are transmitted to the main control circuit 300.

[0032] The main control circuit 300 can be the smallest unit of a microcontroller, and the microcontroller model can be selected according to the user's needs. The main control circuit compares the amplitude voltage VA with the voltage protection threshold to obtain a first comparison result; it compares the phase voltage frequency FRE_A with the frequency protection threshold to obtain a second comparison result; and outputs a drive signal based on the first and second comparison results. The voltage protection threshold can be set according to the user's needs, for example, the voltage protection threshold can be set to be 30% higher than the mains power (i.e., 220VAC); the frequency protection threshold can be set according to the user's needs, for example, the frequency protection threshold can be set to be less than or equal to 49Hz or greater than or equal to 50.5Hz.

[0033] In one example, if the amplitude voltage VA is greater than 30% of the mains voltage (i.e., 220VAC), an overvoltage fault is determined to have occurred in the mains voltage; if the amplitude voltage VA is less than 30% of the mains voltage (i.e., 220VAC), an undervoltage fault is determined to have occurred in the mains voltage. If the phase voltage frequency FRE_A is less than or equal to 49Hz, an underfrequency fault is determined to have occurred in the mains voltage; if the phase voltage frequency FRE_A is greater than or equal to 50.5Hz, an overfrequency fault is determined to have occurred in the mains voltage. When any fault occurs, the main control circuit 300 outputs a drive signal to drive the motor, thereby controlling the circuit breaker to perform a tripping operation.

[0034] Based on the set voltage and frequency protection thresholds, by comparing the amplitude voltage VA with the voltage protection threshold and the phase voltage frequency FRE_A with the frequency protection threshold, a fault can be determined, and a corresponding drive signal is output. This causes the motor drive circuit 400 to drive the motor to operate, thereby controlling the circuit breaker to perform opening or closing operations. For example, when the amplitude voltage VA is higher than 30% of the mains voltage (i.e., 220VAC), or when the phase voltage frequency FRE_A is less than or equal to 49Hz or greater than or equal to 50.5Hz, indicating a fault in the mains voltage, the circuit breaker enters a fault protection state, and the motor drive controls the circuit breaker to perform an opening operation. After the mains voltage recovers, the circuit breaker returns from the fault protection state to the normal operating state, and the motor drive controls the circuit breaker to perform a closing operation.

[0035] In this embodiment, a voltage acquisition circuit samples the phase voltage amplitude to obtain the amplitude voltage, thereby detecting the grid voltage. A frequency acquisition circuit obtains the phase voltage frequency based on the amplitude voltage and a reference voltage, thereby detecting the grid frequency. The main control circuit outputs a drive signal based on the amplitude voltage and the phase voltage frequency, comparing the amplitude voltage with a voltage protection threshold to obtain a first comparison result; comparing the phase voltage frequency with a frequency protection threshold to obtain a second comparison result; and outputting a drive signal based on the first and second comparison results. Finally, a motor drive circuit drives the motor to operate according to the drive signal, thereby controlling the circuit breaker to perform opening or closing operations. By detecting the grid amplitude and frequency, and based on the comparison results of the amplitude voltage and the voltage protection threshold, as well as the comparison results of the phase voltage frequency and the frequency protection threshold, the circuit breaker is controlled to perform opening or closing operations, providing corresponding protection functions.

[0036] In one possible embodiment, see Figure 2 , Figure 2 A schematic diagram of the circuit structure of a voltage acquisition circuit provided in an embodiment of this application is shown below. Figure 2As shown, the voltage acquisition circuit 100 includes: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a clamping diode D1, and a first capacitor C1.

[0037] The first end of the first resistor R1 is electrically connected to the input terminal VIN of the voltage acquisition circuit 100. The second end of the first resistor R1 is electrically connected to the first end of the second resistor R2. The second end of the second resistor R2 is electrically connected to the first end of the third resistor R3. The second end of the third resistor R3 is electrically connected to the second end of the fourth resistor R4, the first end of the fifth resistor R5, the clamping end of the clamping diode D1, the first end of the first capacitor C1, and the output terminal P1 of the voltage acquisition circuit, respectively, for outputting the amplitude voltage VA.

[0038] The cathode of clamping diode D1 is electrically connected to the first terminal of the fourth resistor R4 to supply the operating voltage VDD.

[0039] The anode of clamping diode D1, the second terminal of the first capacitor C1, and the second terminal of the fifth resistor R5 are all grounded.

[0040] In practical project applications, the operating voltage VDD is usually set to 3.3V or 5V.

[0041] The first terminal of the first resistor R1 is electrically connected to the input terminal VIN of the voltage acquisition circuit 100, and is used to input the phase voltage NA. The phase voltage NA is an AC signal with a sinusoidal waveform. It is stepped down by the first resistor R1, the second resistor R2, the third resistor R3, and the fifth resistor R5. Since the main control circuit cannot detect negative voltage, it is necessary to convert the stepped-down AC signal into a positive voltage. In this application, the operating voltage VDD is divided by the fourth resistor R4 and the fifth resistor R5. The phase voltage NA after voltage division is superimposed on the operating voltage VDD after voltage division at the first terminal of the fifth resistor R5. The waveform of the final output amplitude voltage VA is the superposition of a small-amplitude sinusoidal signal and a bias voltage, converting the amplitude voltage VA into a signal that the main control circuit can detect. Among them, the small-amplitude sinusoidal signal is the phase voltage NA after voltage division, and the bias voltage is the operating voltage VDD after voltage division. For example, the 220VAC phase voltage NA can be converted into an amplitude voltage VA of 0~3.3V. The amplitude voltage VA is directly input into the microcontroller for acquisition, and the real-time phase voltage amplitude can be calculated.

[0042] See Figure 3 , Figure 3 A waveform diagram of phase voltage and amplitude voltage provided in an embodiment of this application is shown below. Figure 3 As shown, the phase voltage is a sinusoidal AC signal, and the amplitude voltage is a sinusoidal signal with a smaller amplitude.

[0043] In one possible embodiment, see Figure 4 , Figure 4 This is a schematic diagram of the circuit structure of a frequency acquisition circuit provided in an embodiment of this application, as shown below. Figure 4 As shown, the frequency acquisition circuit 200 includes a reference voltage generation circuit 20 and a comparison circuit 21.

[0044] Reference voltage generation circuit 20 is used to generate reference voltage VREF.

[0045] Comparison circuit 21 is used to compare the amplitude voltage VA and the reference voltage VREF to obtain the phase voltage frequency FRE_A.

[0046] In one possible embodiment, see Figure 4 The reference voltage generation circuit 20 may include: a sixth resistor R6, a seventh resistor R7, and a second capacitor C2.

[0047] The first end of the sixth resistor R6 is used to connect the working voltage VDD. The second end of the sixth resistor R6 is electrically connected to the first end of the seventh resistor R7, the first end of the second capacitor C2, and the output end of the reference voltage generation circuit 20, respectively, and is used to output the reference voltage VREF.

[0048] The second terminal of the seventh resistor R7 and the second terminal of the second capacitor C2 are both grounded.

[0049] In this embodiment, the reference voltage generation circuit 20 divides the working voltage VDD through the sixth resistor R6 and the seventh resistor R7, and then filters it through the second capacitor C2 to generate the reference voltage VREF.

[0050] In one possible embodiment, see Figure 4 The comparator circuit 21 may include: comparator U1, eighth resistor R8, ninth resistor R9, tenth resistor R10, and third capacitor C3.

[0051] The first end of the eighth resistor R8 is electrically connected to the first input terminal P2 of the frequency acquisition circuit 200, and the second end of the eighth resistor R8 is electrically connected to the positive input terminal of the comparator U1 and the first end of the ninth resistor R9.

[0052] The inverting input of comparator U1 is electrically connected to the output of the reference voltage generation circuit and serves as the second input P3 of the frequency acquisition circuit 200, used to connect the reference voltage VREF.

[0053] The second end of the ninth resistor R9 is electrically connected to the output end of comparator U1, the second end of the tenth resistor R10, and the first end of the third capacitor C3, and serves as the output end P4 of the frequency acquisition circuit 200, used to output the phase voltage frequency FRE_A.

[0054] The first terminal of the tenth resistor R10 is used to connect to the working voltage VDD, and the second terminal of the third capacitor C3 is grounded.

[0055] In this embodiment, the first end of the eighth resistor R8 is electrically connected to the first input terminal P2 of the frequency acquisition circuit 200 to receive the amplitude voltage VA. Then, the positive input terminal of the comparator U1 is connected to the amplitude voltage VA, and the inverting input terminal of the comparator U1 is connected to the reference voltage VREF. The comparator circuit 21 compares the reference voltage VREF and the amplitude voltage VA through the comparator U1. When the amplitude voltage VA is higher than the reference voltage VREF, the output terminal of the comparator U1 outputs a high level; when the amplitude voltage VA is lower than the reference voltage VREF, the output terminal of the comparator U1 outputs a low level.

[0056] The comparator circuit 21 can output a square wave signal corresponding to the frequency of the amplitude voltage VA. Since the frequency of the amplitude voltage VA is equal to the frequency of the phase voltage, the frequency acquisition circuit outputs a square wave signal corresponding to the frequency of the phase voltage. Finally, the main control circuit uses a timer to obtain the time of one period (two adjacent rising or falling edges) based on the rising or falling edge of the square wave signal, and calculates the reciprocal of this time to obtain the phase voltage frequency FRE_A.

[0057] See Figure 5 , Figure 5 A waveform diagram of a frequency acquisition circuit provided in an embodiment of this application is shown below. Figure 5 As shown, when the amplitude voltage VA is higher than the reference voltage VREF, the output of comparator U1 is high, which is the high level in the square wave signal; when the amplitude voltage VA is lower than the reference voltage VREF, the output of comparator U1 is low, which is the low level in the square wave signal.

[0058] See Figure 6 , Figure 6 A schematic diagram of a periodic waveform of a phase voltage frequency provided in an embodiment of this application is shown below. Figure 6 As shown, the main control circuit can use a timer to obtain the time T of one period (two adjacent rising edges) based on the rising edge of the square wave signal, and then calculate the phase voltage frequency FRE_A by taking the reciprocal of this time.

[0059] In one possible embodiment, see Figure 7 , Figure 7 This is a schematic diagram of the circuit structure of a motor drive circuit provided in an embodiment of this application, as shown below. Figure 7 As shown, the drive signals include the first drive signal IN1 and the second drive signal IN2. The motor drive circuit 400 includes an eleventh resistor R11, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, and a motor drive chip U2.

[0060] The second terminal of the motor driver chip U2 is connected to the first drive signal IN1, the third terminal of the motor driver chip U2 is connected to the second drive signal IN2, the fourth terminal of the motor driver chip U2 is electrically connected to the first terminal of the eleventh resistor R11, and the second terminal of the eleventh resistor R11 is grounded.

[0061] The fifth terminal of the motor driver chip U2 is grounded.

[0062] The sixth terminal of the motor driver chip U2 is electrically connected to the first terminal of the fourth capacitor C4 and the first input terminal M_1 of the motor.

[0063] The seventh terminal of the motor driver chip U2 is electrically connected to the second terminal of the fourth capacitor C4 and the second input terminal M_2 of the motor.

[0064] The eighth terminal of the motor driver chip U2 is electrically connected to the first terminal of the fifth capacitor C5 and the first terminal of the sixth capacitor C6, respectively, and is used to connect the driving voltage V_12V.

[0065] The second terminal of the fifth capacitor C5 and the second terminal of the sixth capacitor C6 are both grounded.

[0066] The motor drive circuit 400 drives the motor to rotate forward or reverse according to the first drive signal IN1 and the second drive signal IN2 output by the main control circuit 300, thereby controlling the circuit breaker to perform opening or closing operations.

[0067] The driving voltage V_12V supplies power to the motor driver chip U2, and the fifth capacitor C5 and the sixth capacitor C6 are used to filter the driving voltage V_12V.

[0068] In one possible embodiment, see Figure 8 , Figure 8 A schematic diagram of the circuit structure of another protection circuit provided in the embodiments of this application is shown below. Figure 8 As shown, the protection circuit also includes a display circuit 500 and a power supply circuit 600.

[0069] The display circuit 500 is electrically connected to the main control circuit 300, and the power supply circuit 600 is electrically connected to the voltage acquisition circuit 100, the frequency acquisition circuit 200, the main control circuit 300, the motor drive circuit 400, and the display circuit 500.

[0070] The display circuit 500 is used to display the operating status of the circuit breaker based on the display signal.

[0071] The power supply circuit 600 is used to output the working voltage VDD and the drive voltage V_12V.

[0072] The power supply circuit provides power to the voltage acquisition circuit 100, frequency acquisition circuit 200, main control circuit 300, motor drive circuit 400 and display circuit 500. The output working voltage VDD supplies power to the voltage acquisition circuit 100, frequency acquisition circuit 200, main control circuit 300 and display circuit 500, and the output drive voltage V_12V supplies power to the motor drive circuit 400.

[0073] The power supply circuit can employ existing AC-DC (alternating current to direct current) converters, DC-DC (direct current to direct current) converters, or LDOs (low-dropout regulators) to convert the phase voltage to the required operating voltage VDD and drive voltage V_12V, for example, converting 220VAC AC voltage to 3.3VDC or 12VDC. This application does not impose specific limitations on the internal circuit structure of the power supply circuit.

[0074] In one possible embodiment, see Figure 9 , Figure 9 This is a schematic diagram of the circuit structure of a display circuit provided in an embodiment of this application, as shown below. Figure 9 As shown, the display signals include a first display signal LED_R and a second display signal LED_G; the display circuit 500 includes: a twelfth resistor R12, a thirteenth resistor R13, a first light-emitting diode LED1, and a second light-emitting diode LED2.

[0075] The first end of the twelfth resistor R12 is electrically connected to the main control circuit 300 and is used to input the first display signal LED_R. The second end of the twelfth resistor R12 is electrically connected to the cathode of the first light-emitting diode LED1.

[0076] The first end of the thirteenth resistor R13 is electrically connected to the main control circuit 300 and is used to input the second display signal LED_G. The second end of the thirteenth resistor R13 is electrically connected to the cathode of the second light-emitting diode LED2.

[0077] The anode of the first light-emitting diode LED1 is electrically connected to the anode of the second light-emitting diode LED2, and is connected to the operating voltage VDD.

[0078] The display circuit controls the first LED1 and the second LED2 to light up according to the first display signal LED_R and the second display signal LED_G output by the main control circuit 300, thereby displaying the working status of the circuit breaker. For example, when the first LED1 is constantly lit, it indicates that the circuit breaker is in normal working condition; when the second LED2 is constantly lit, it indicates that the circuit breaker is in abnormal working condition; when the second LED2 flashes at a certain frequency, it indicates that the circuit breaker is in overvoltage working condition.

[0079] The embodiments of this application sample the amplitude and frequency of the phase voltage through external voltage acquisition circuits and frequency acquisition circuits, which is more flexible and lower in cost compared with using a dedicated metering chip to collect the amplitude and frequency of the phase voltage.

[0080] This application also provides a substrate, including the protection circuit described above.

[0081] This application also provides a circuit breaker, including: a substrate as described above.

[0082] This circuit breaker can be a photovoltaic grid-connected circuit breaker used in photovoltaic grid-connected systems.

[0083] Finally, it should be noted that the above embodiments are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A protection circuit, characterized in that, The protection circuit includes: a voltage acquisition circuit, a frequency acquisition circuit, a main control circuit, and a motor drive circuit; The input terminal of the voltage acquisition circuit is used to connect to the phase voltage, and the output terminal of the voltage acquisition circuit is electrically connected to the first input terminal of the frequency acquisition circuit and the main control circuit, respectively; the second input terminal of the frequency acquisition circuit is used to connect to the reference voltage, and the output terminal of the frequency acquisition circuit is electrically connected to the main control circuit; the main control circuit is electrically connected to the motor drive circuit. The voltage acquisition circuit is used to sample the voltage amplitude of the phase voltage to obtain the amplitude voltage; The frequency acquisition circuit is used to obtain the phase voltage frequency based on the amplitude voltage and the reference voltage; The main control circuit is used to compare the amplitude voltage with the voltage protection threshold to obtain a first comparison result; compare the phase voltage frequency with the frequency protection threshold to obtain a second comparison result; and output a drive signal according to the first comparison result and the second comparison result. The motor drive circuit is used to drive the motor to operate according to the drive signal, so as to control the circuit breaker to perform opening or closing operations.

2. The protection circuit according to claim 1, characterized in that, The voltage acquisition circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a clamping diode, and a first capacitor; The first end of the first resistor is electrically connected to the input terminal of the voltage acquisition circuit, the second end of the first resistor is electrically connected to the first end of the second resistor, the second end of the second resistor is electrically connected to the first end of the third resistor, and the second end of the third resistor is electrically connected to the second end of the fourth resistor, the first end of the fifth resistor, the clamping terminal of the clamping diode, the first end of the first capacitor, and the output terminal of the voltage acquisition circuit, respectively, for outputting the amplitude voltage; The cathode of the clamping diode is electrically connected to the first end of the fourth resistor for use in applying the operating voltage. The anode of the clamping diode, the second terminal of the first capacitor, and the second terminal of the fifth resistor are all grounded.

3. The protection circuit according to claim 2, characterized in that, The frequency acquisition circuit includes a reference voltage generation circuit and a comparison circuit; The reference voltage generation circuit is used to generate the reference voltage; The comparison circuit is used to compare the amplitude voltage with the reference voltage to obtain the phase voltage frequency.

4. The protection circuit according to claim 3, characterized in that, The reference voltage generation circuit includes: a sixth resistor, a seventh resistor, and a second capacitor; The first end of the sixth resistor is used to connect to the working voltage, and the second end of the sixth resistor is electrically connected to the first end of the seventh resistor, the first end of the second capacitor, and the output end of the reference voltage generation circuit, respectively, for outputting the reference voltage. The second terminal of the seventh resistor and the second terminal of the second capacitor are both grounded.

5. The protection circuit according to claim 3, characterized in that, The comparison circuit includes: a comparator, an eighth resistor, a ninth resistor, a tenth resistor, and a third capacitor; The first end of the eighth resistor is electrically connected to the first input terminal of the frequency acquisition circuit, and the second end of the eighth resistor is electrically connected to the positive input terminal of the comparator and the first end of the ninth resistor, respectively. The inverting input terminal of the comparator is electrically connected to the output terminal of the reference voltage generation circuit, and serves as the second input terminal of the frequency acquisition circuit for connecting the reference voltage. The second end of the ninth resistor is electrically connected to the output end of the comparator, the second end of the tenth resistor, and the first end of the third capacitor, and serves as the output end of the frequency acquisition circuit for outputting the phase voltage frequency. The first end of the tenth resistor is used to connect to the operating voltage, and the second end of the third capacitor is grounded.

6. The protection circuit according to any one of claims 2-5, characterized in that, The driving signal includes a first driving signal and a second driving signal, and the motor driving circuit includes an eleventh resistor, a fourth capacitor, a fifth capacitor, a sixth capacitor, and a motor driving chip. The second terminal of the motor driver chip is connected to the first drive signal, the third terminal of the motor driver chip is connected to the second drive signal, the fourth terminal of the motor driver chip is electrically connected to the first terminal of the eleventh resistor, and the second terminal of the eleventh resistor is grounded. The fifth terminal of the motor drive chip is grounded; The sixth terminal of the motor driver chip is electrically connected to the first terminal of the fourth capacitor and the first input terminal of the motor, respectively. The seventh terminal of the motor driver chip is electrically connected to the second terminal of the fourth capacitor and the second input terminal of the motor, respectively. The eighth terminal of the motor drive chip is electrically connected to the first terminal of the fifth capacitor and the first terminal of the sixth capacitor, respectively, and is used to receive the drive voltage. The second terminal of the fifth capacitor and the second terminal of the sixth capacitor are both grounded.

7. The protection circuit according to claim 6, characterized in that, The protection circuit also includes: a display circuit and a power supply circuit; The display circuit is electrically connected to the main control circuit, and the power supply circuit is electrically connected to the voltage acquisition circuit, the frequency acquisition circuit, the main control circuit, the motor drive circuit, and the display circuit, respectively. The display circuit is used to display the operating status of the circuit breaker according to the display signal; The power supply circuit is used to output the operating voltage and the driving voltage.

8. The protection circuit according to claim 7, characterized in that, The display signal includes a first display signal and a second display signal; the display circuit includes: a twelfth resistor, a thirteenth resistor, a first light-emitting diode, and a second light-emitting diode; The first end of the twelfth resistor is electrically connected to the main control circuit and is used to receive the first display signal; the second end of the twelfth resistor is electrically connected to the cathode of the first light-emitting diode. The first end of the thirteenth resistor is electrically connected to the main control circuit for receiving the second display signal, and the second end of the thirteenth resistor is electrically connected to the cathode of the second light-emitting diode. The anode of the first light-emitting diode is electrically connected to the anode of the second light-emitting diode and is connected to the operating voltage.

9. A substrate, characterized in that, include: The protection circuit as described in any one of claims 1-8.

10. A circuit breaker, characterized in that, include: The substrate as described in claim 9.

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