Control circuit applied to photovoltaic turn-off device, photovoltaic turn-off device and photovoltaic system

Abstract

The invention discloses a control circuit applied to a photovoltaic turn-off device, the photovoltaic turn-off device and a photovoltaic system, and belongs to the field of photovoltaic technologies. In the control circuit provided by the embodiment of the invention, a switch module is connected with a photovoltaic module. The switch control module is connected with the switch module and used for outputting control voltage according to the comparison result of the first voltage and the second voltage and controlling the on-off state of the switch module. One end of the hysteresis filtering module is connected between the switch control module and the switch module, the other end of the hysteresis filtering module is connected between the first voltage dividing unit and the switch control module, and when the control voltage is equal to the input voltage, the hysteresis filtering module is used for staggering threshold points of on and off of the switch module. Therefore, the switch module is prevented from being repeatedly switched on and switched off under the influence of voltage oscillation at the switching-on moment and the switching-off moment, accurate control over the switch module is achieved, the service life of the switch module is prolonged, and the reliability and the safety of the photovoltaic system are further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic, in particular to a control circuit applied to a photovoltaic shutdown device, a photovoltaic shutdown device and a photovoltaic system. BACKGROUND

[0002] The photovoltaic shutdown device is a safety device installed in a photovoltaic system, which is used to quickly cut off the direct current side voltage of the photovoltaic module in an emergency or when maintenance is needed. In the photovoltaic fast shutdown device, a high-power metal-oxide-semiconductor field-effect transistor (MOSFET) is used to control the on-off between the photovoltaic module and the inverter, so as to cut off the photovoltaic module in abnormal conditions, reduce losses, and ensure property and personnel safety.

[0003] At present, the driving control of the MOSFET can be controlled by a PWM signal based on a digital MCU or by a hardware control circuit. The PWM signal based on the digital MCU is accurate, but also has problems such as high cost and response delay. In the process of controlling the field-effect transistor in the photovoltaic shutdown device, the pure hardware control method is prone to repeated opening and closing of the field-effect transistor due to voltage oscillation at the opening and closing time of the field-effect transistor, which damages the field-effect transistor. SUMMARY

[0004] The present application provides a control circuit applied to a photovoltaic shutdown device, a photovoltaic shutdown device and a photovoltaic system to solve at least one of the above technical problems.

[0005] The control circuit applied to the photovoltaic shutdown device of the present application is applied to a photovoltaic system, and the photovoltaic system includes a photovoltaic module. The control circuit applied to the photovoltaic shutdown device includes: a switch module connected with the photovoltaic module, the switch module being a field-effect transistor; a voltage dividing module including a first voltage dividing unit and a second voltage dividing unit connected in parallel, the first voltage dividing unit being configured to output a first voltage according to an input voltage, and the second voltage dividing unit being configured to output a second voltage according to the input voltage; a switch control module connected with the first voltage dividing unit, the second voltage dividing unit and the switch module respectively, the switch control module being configured to output a control voltage according to a comparison result of the first voltage and the second voltage, wherein, in the case that the first voltage is greater than the second voltage, the control voltage is equal to the input voltage, so as to make the switch module open; and in the case that the first voltage is less than or equal to the second voltage, the control voltage is zero, so as to make the switch module close. a hysteresis filter module, one end of which is connected between the switch control module and the switch module, and the other end of which is connected between the first voltage dividing unit and the switch control module, the hysteresis filter module being configured to stagger the threshold points of turn-on and turn-off of the switch module when the control voltage is equal to the input voltage.

[0006] In some embodiments, the first voltage dividing unit comprises a first resistor and a second resistor, one end of the first resistor being connected to one end of the second resistor, and the other end of the second resistor being grounded, and one end of the switch control module being connected between the first resistor and the second resistor. The hysteresis filter module comprises a hysteresis resistor, one end of the hysteresis resistor being connected between the switch control module and the switch module, and the other end of the hysteresis resistor being connected between the first resistor and the second resistor. The resistance value of the hysteresis resistor is less than the resistance value of the first resistor.

[0007] In some embodiments, the hysteresis filter module further comprises a hysteresis capacitor, the hysteresis capacitor being connected in parallel across the hysteresis resistor, and configured to form a low-pass filter with the hysteresis resistor.

[0008] In some embodiments, the second voltage dividing unit comprises a third resistor and a first voltage stabilizing tube, one end of the third resistor being connected to one end of the first voltage stabilizing tube, and the other end of the first voltage stabilizing tube being grounded, and one end of the switch control module being connected between the third resistor and the first voltage stabilizing tube. The third resistor and the first voltage stabilizing tube are configured to divide the input voltage to obtain the second voltage, and input the second voltage to the switch control module.

[0009] In some embodiments, the first voltage dividing unit further comprises a first capacitor, the first capacitor being connected in parallel to the second resistor. The first capacitor and the first resistor form a low-pass filter, and are configured to filter the input voltage.

[0010] The second voltage dividing unit further comprises a second capacitor, the second capacitor being connected in parallel to the first voltage stabilizing tube. The second capacitor and the third resistor form a low-pass filter, and are configured to filter the input voltage.

[0011] In some embodiments, the first voltage dividing unit further comprises a third capacitor, the third capacitor being connected in parallel to the first resistor. The third capacitor is configured to filter the input voltage; and / or The second voltage dividing unit further comprises a fourth capacitor, the fourth capacitor being connected in parallel to the third resistor. The fourth capacitor is configured to filter the input voltage.

[0012] In some embodiments, the control circuit applied to the photovoltaic shutdown device further comprises a fourth resistor, a fifth capacitor and a second voltage stabilizer, one end of the fourth resistor is connected with the fifth capacitor, the other end of the fifth capacitor is grounded, the fifth capacitor is connected with the voltage dividing module in parallel, and the second voltage stabilizer is connected with the fifth capacitor in parallel. The fourth resistor and the fifth capacitor are configured to limit current filtering of the power supply voltage, and the second voltage stabilizer is configured to stabilize the power supply voltage to obtain the input voltage.

[0013] In some embodiments, the control circuit applied to the photovoltaic shutdown device further comprises a diode, and a negative electrode of the diode is connected with one end of the fourth resistor. The diode is configured to prevent the input voltage from being reversed.

[0014] The photovoltaic shutdown device of the embodiments of the present application comprises the control circuit applied to the photovoltaic shutdown device of any of the above embodiments.

[0015] The photovoltaic system of the embodiments of the present application comprises the photovoltaic shutdown device of the above embodiments.

[0016] In the control circuit applied to the photovoltaic shutdown device, the photovoltaic shutdown device and the photovoltaic system of the embodiments of the present application, the input voltage is divided by the voltage dividing module, and a hysteresis filter module is further provided, the control voltage is determined by the switching control module according to the divided input voltage and the hysteresis width of the hysteresis filter module, and the on-off state of the switching module is controlled according to the control voltage. In this way, the switching module is prevented from being repeatedly turned on and off at the turn-on moment and the turn-off moment due to voltage oscillation, accurate control of the switching module is achieved, the service life of the switching module is improved, and the reliability and safety of the photovoltaic system are also improved.

[0017] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the drawings needed to be used in the embodiments or the related art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown. Figure 1is a module schematic diagram of a control circuit applied to a photovoltaic shutdown device according to some embodiments of the present application; Figure 2 is a circuit schematic diagram of a control circuit applied to a photovoltaic shutdown device according to some embodiments of the present application; Figure 3 is a module schematic diagram of a photovoltaic system according to some embodiments of the present application; Figure 4 is a circuit schematic diagram of a control circuit applied to a photovoltaic shutdown device according to some embodiments of the present application; Figure 5 is a waveform schematic diagram of a first voltage and a second voltage in a shutdown process of a control circuit applied to a photovoltaic shutdown device according to some embodiments of the present application; Figure 6 is a schematic diagram of a control voltage varying with a stabilized voltage of a control circuit applied to a photovoltaic shutdown device according to some embodiments of the present application; Figure 7 is a circuit schematic diagram of a control circuit applied to a photovoltaic shutdown device according to some embodiments of the present application; Figure 8 is a module schematic diagram of a photovoltaic shutdown device according to some embodiments of the present application; Figure 9 is a module schematic diagram of a photovoltaic system according to some embodiments of the present application.

[0019] BRIEF DESCRIPTION OF DRAWINGS Control circuit 100, switch module 10, switch control module 20, voltage division module 30, voltage stabilization module 40, hysteresis filter module 50, field effect transistor Q1, operational amplifier op1, first resistor R1, second resistor R2, third resistor R3, fourth resistor R4, fifth resistor R5, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, fifth capacitor C5, hysteresis resistor R6, hysteresis capacitor C6, first zener D1, second zener D2, diode D3, photovoltaic shutdown device 101, photovoltaic system 200, photovoltaic assembly 210, inverter 220, transmitter 230. DETAILED DESCRIPTION

[0020] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like reference numerals are used throughout the figures to refer to the same or like components. The embodiments described below are exemplary and are not intended to be limiting of the present application.

[0021] Please refer to Figures 1 to 3The embodiment of the present application provides a control circuit 100 applied to a photovoltaic shutdown device 101. The photovoltaic shutdown device 101 is applied to a photovoltaic system 200, the photovoltaic system 200 comprises an inverter 220 and a photovoltaic assembly 210, and the control circuit 100 applied to the photovoltaic shutdown device 101 comprises a switch module 10, a switch control module 20, a hysteresis filtering module 50 and a voltage division module 30. The switch module 10 is connected with the photovoltaic assembly 210. The switch module 10 is a field effect transistor Q1. The voltage division module 30 comprises a first voltage division unit and a second voltage division unit in parallel, the first voltage division unit is used for outputting a first voltage according to an input voltage, and the second voltage division unit is used for outputting a second voltage according to the input voltage. The switch control module 20 is connected with the first voltage division unit, the second voltage division unit and the switch module 10 respectively, and the switch control module 20 is used for outputting a control voltage according to a comparison result of the first voltage and the second voltage. Wherein, in the case that the first voltage is greater than the second voltage, the control voltage is equal to the input voltage, so that the switch module 10 is turned on, and in the case that the first voltage is less than or equal to the second voltage, the control voltage is zero, so that the switch module 10 is turned off. The hysteresis filtering module 50 is connected between the switch control module 20 and the switch module 10 at one end and connected between the first voltage division unit and the switch control module 20 at the other end, and the hysteresis filtering module 50 is used for staggering threshold points of turning on and turning off of the switch module 10 in the case that the control voltage is equal to the input voltage.

[0022] In the control circuit 100 applied to the photovoltaic shutdown device 101 of the embodiment of the present application, the input voltage is processed by voltage division through the voltage division module 30, and the hysteresis filtering module 50 is further arranged, the switch control module 20 determines the control voltage according to the input voltage after voltage division and the hysteresis width of the hysteresis filtering module 50, so as to control the on-off state of the switch module 10 according to the control voltage. In this way, the switch module 10 is prevented from being repeatedly turned on and turned off due to the influence of voltage oscillation at the turning-on time and the turning-off time, accurate control of the switch module 10 is realized, the service life of the switch module 10 is improved, and the reliability and safety of the photovoltaic system 200 are further improved.

[0023] Specifically, the control circuit 100 is applied to the photovoltaic system 200, and the photovoltaic system 200 comprises the inverter 220 and the photovoltaic assembly 210. The number of the photovoltaic assembly 210 is multiple, and a plurality of control circuits 100 can be arranged in each photovoltaic system 200, and the control circuit 100 is used for controlling the on-off between the photovoltaic assembly 210 and the inverter 220.

[0024] The control circuit 100 comprises a circuit input end and a circuit output end, the circuit input end is used for connecting a control power supply, an independent external power supply can be used as the control power supply, or the photovoltaic assembly 210 is directly used as the control power supply. The voltage division module 30, the switch control module 20 and the switch module 10 are sequentially connected between the circuit input end and the circuit output end of the control circuit 100.

[0025] The input voltage input to the voltage dividing module 30 is denoted as Vcc, and the input voltage Vcc is input to the switch control module 20 after being processed by the voltage dividing module 30. The control circuit 100 further comprises a hysteresis filter module 50 connected in parallel with the switch control module 20, and the hysteresis filter module 50 can generate a hysteresis width. The presence of the hysteresis width can offset the threshold points of the switch module 10 turning on and turning off, thereby avoiding the switch module 10 oscillating between turning on and turning off.

[0026] The switch control module 20 can determine the control voltage according to the input voltage Vcc processed by the voltage dividing and the hysteresis width, and the control voltage can be denoted as Vout. The control voltage Vout is input to the switch module 10 to control the on-off state of the switch module 10.

[0027] The switch control module 20 can adopt an operational amplifier op1, which comprises a non-inverting input terminal, an inverting input terminal, and an operational amplifier output terminal. The non-inverting input terminal and the inverting input terminal of the operational amplifier op1 are also the input terminals of the switch control module 20, and the operational amplifier output terminal of the operational amplifier op1 is also the output terminal of the switch control module 20.

[0028] The voltage dividing module 30 comprises a first voltage dividing unit and a second voltage dividing unit. The non-inverting input terminal is connected to the first voltage dividing unit, the inverting input terminal is connected to the second voltage dividing unit, and the operational amplifier output terminal is connected to the switch module 10. The first voltage dividing unit is used to perform first voltage dividing on the input voltage Vcc to obtain a first voltage denoted as VIN+, which can be input to the non-inverting input terminal. The second voltage dividing unit is used to perform second voltage dividing on the input voltage Vcc to obtain a second voltage denoted as VIN-, which can be input to the inverting input terminal.

[0029] The operational amplifier output terminal is connected to the switch module 10, the operational amplifier op1 compares the input first voltage VIN+ and the second voltage VIN- to determine the control voltage Vout, which is output to the switch module 10 by the operational amplifier output terminal. The switch module 10 is a field effect transistor Q1. In an example, as shown in FIG. 2, the switch module 10 can adopt an N-channel field effect transistor, and the gate of the field effect transistor Q1 is connected to the switch control module 20. Figure 2

[0030] When the first voltage VIN+ is greater than the second voltage VIN-, the control voltage Vout is output as a high level, at this time Vout=Vcc. The control voltage Vout drives the gate of the field effect transistor Q1 to realize the turning on of the field effect transistor Q1, i.e., the turning on of the switch module 10.

[0031] ​When the first voltage VIN+ is less than the second voltage VIN-, the control voltage Vout outputs a low level of 0, and the gate of the field-effect transistor Q1 discharges to the operational amplifier op1's output terminal, thus turning off the field-effect transistor Q1, which is also turning off the switching module 10.

[0032] In addition to being connected to the switch control module 20, the switch module 10 is also connected in series or parallel to the photovoltaic module 210. Therefore, by controlling the on / off state of the switch module 10, the connection state between the photovoltaic module 210 and the inverter 220 can be controlled. When the switch module 10 is connected in series with the photovoltaic module 210, the source of the field-effect transistor Q1 is connected to one photovoltaic module 210, that is... Figure 2 The second interface P2 is used to connect one photovoltaic module 210; the drain of the field-effect transistor Q1 is connected to another photovoltaic module 210, that is... Figure 2 The first interface P1 is used to connect to another photovoltaic module 210.

[0033] When the switching module 10 is connected in parallel with the photovoltaic module 210, the source and drain of the field-effect transistor Q1 are connected to the two ends of the photovoltaic module 210, that is... Figure 2 The first interface P1 and the second interface P2 are connected to the two ends of the same photovoltaic module 210. When the control voltage Vout output by the switch control module 20 is high, the switch module 10 is turned on; when the control voltage Vout output by the switch control module 20 is low, the switch module 10 is turned off.

[0034] When the switch module 10 is turned on, the photovoltaic module 210 is connected to the inverter 220; when the switch module 10 is turned off, the connection between the photovoltaic module 210 and the inverter 220 is disconnected.

[0035] In this embodiment, a purely hardware-based control circuit 100 for turning on and off a photovoltaic switch module 10 is proposed for a photovoltaic switch 101. Considering the fluctuation of the input voltage Vcc during the on and off moments of the switch module 10, a voltage divider module 30 is used to divide the input voltage Vcc, and a hysteresis filter module 50 is also provided. The switch control module 20 determines the control voltage Vout based on the input voltage Vcc after voltage division and the hysteresis width, and controls the on / off state of the switch module 10 according to the control voltage Vout.

[0036] Therefore, in the case that the noise or disturbance of the voltage is less than the hysteresis width, the switch module 10 will not be turned on or turned off by mistake. During the turning on and turning off of the switch module 10, the problem that the switch module 10 is repeatedly turned on and turned off due to the jitter of the first voltage VIN+ and the second voltage VIN- and the oscillation of the control voltage can be avoided, so that the switch module 10 can be accurately and reliably turned on and turned off. In addition, the turning on and turning off of the switch module 10 is controlled by pure hardware, the sensitivity to electromagnetic interference is significantly reduced, the cost is low, and the reliability and safety of the photovoltaic system 200 are improved.

[0037] Referring to Figure 4 In some embodiments, the first voltage dividing unit includes a first resistor R1 and a second resistor R2, one end of the first resistor R1 is connected to one end of the second resistor R2, the other end of the second resistor R2 is grounded, and one end of the switch control module 20 is connected between the first resistor R1 and the second resistor R2. The hysteresis filter module 50 includes a hysteresis resistor R6, one end of the hysteresis resistor R6 is connected between the switch control module 20 and the switch module 10, and the other end of the hysteresis resistor R6 is connected between the first resistor R1 and the second resistor R2. The resistance value of the hysteresis resistor R6 is less than the resistance value of the first resistor R1.

[0038] Specifically, the first voltage dividing unit includes a first resistor R1 and a second resistor R2. One end of the first resistor R1 is connected to the circuit input end, the other end of the first resistor R1 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is grounded. The non-inverting input end of the operational amplifier op1 is connected between the first resistor R1 and the second resistor R2.

[0039] The first resistor R1 and the second resistor R2 are used for voltage dividing processing of the input voltage Vcc to obtain the first voltage VIN+ for inputting to the non-inverting input end. The stable voltage of the first voltage VIN+ is determined by the voltage dividing value of the first resistor R1 and the second resistor R2, which is represented by K3.

[0040] The hysteresis filter module 50 includes a hysteresis resistor R6, one end of the hysteresis resistor R6 is connected to the non-inverting input end of the operational amplifier op1, and the other end of the hysteresis resistor R6 is connected between the operational amplifier op1 and the switch module 10. The hysteresis resistor R6 is used to determine the first threshold value and the second threshold value corresponding to the hysteresis width.

[0041] The resistance of the hysteresis resistor R6 is less than that of the first resistor R1. During the turn-on process of the switching module 10, when the control voltage Vout equals the input voltage Vcc, the second resistor R2 and the hysteresis resistor R6 are connected in series, and the total resistance of the second resistor R2 and the hysteresis resistor R6 is less than the total resistance of the first resistor R1 and the second resistor R2. At this time, the current increases, and the voltage across the second resistor R2 increases instantaneously, that is, the first voltage VIN+ increases instantaneously, causing the fluctuation range of the first voltage VIN+ to be offset from the fluctuation range of the second voltage VIN-.

[0042] Similarly, such as Figure 5 As shown, during the turn-off process of the switching module 10, when the control voltage Vout equals zero, the voltage across the second resistor R2 decreases instantaneously, meaning the first voltage VIN+ decreases instantaneously as well. This causes the fluctuation range of the first voltage VIN+ to be offset from the fluctuation range of the second voltage VIN-. This avoids repeated switching on and off caused by voltage fluctuations in the second resistor R2.

[0043] The first threshold is denoted by K1, the second threshold by K2, and K1-K2 is the hysteresis width. Due to the existence of the hysteresis width, such as Figure 6 As shown, when the input voltage Vcc is greater than the first threshold K1, the field-effect transistor Q1 is turned on.

[0044] When the input voltage Vcc is less than the second threshold K2, the field-effect transistor Q1 is turned off. The stable value K0 of the input voltage Vcc is greater than the first threshold K1, and the first threshold K1 is greater than the second threshold K2. As long as the amplitude of the noise or disturbance of the input voltage Vcc is less than the hysteresis width, there will be no false turn-on or turn-off.

[0045] Please see Figure 2 In some embodiments, the hysteresis filter module 50 further includes a hysteresis capacitor C6, which is connected in parallel across the hysteresis resistor R6 to form a low-pass filter with the hysteresis resistor R6.

[0046] Specifically, the hysteresis capacitor C6 is connected in parallel across the hysteresis resistor R6. Together, the hysteresis capacitor C6 and the hysteresis resistor R6 form a low-pass filter, which enhances the anti-interference capability and stability of the control circuit 100 and prevents oscillation.

[0047] Please see Figure 4In some embodiments, the second voltage dividing unit includes a third resistor R3 and a first voltage stabilizing tube D1. The third resistor R3 is connected to one end of the first voltage stabilizing tube D1, the other end of the first voltage stabilizing tube D1 is grounded, and one end of the switch control module 20 is connected between the third resistor R3 and the first voltage stabilizing tube D1. The third resistor R3 and the first voltage stabilizing tube D1 are used to divide the input voltage and obtain a second voltage to input the switch control module 20. The resistance value of the first resistor R1 and the second resistor R2 in parallel is less than the resistance value of the third resistor R3.

[0048] Specifically, the second voltage dividing unit includes a third resistor R3 and a first voltage stabilizing tube D1, one end of the third resistor R3 is connected to the circuit input end, the other end is connected to one end of the first voltage stabilizing tube D1, the other end of the first voltage stabilizing tube D1 is grounded, and the inverting input end is connected between the third resistor R3 and the first voltage stabilizing tube D1.

[0049] The third resistor R3 and the first voltage stabilizing tube D1 are used to divide the input voltage Vcc and obtain a second voltage VIN- to input the inverting input end. The stable voltage of the second voltage VIN- is determined by the voltage stabilizing value of the third resistor R3 and the first voltage stabilizing tube D1, denoted by K4.

[0050] Please refer to Figure 4 In some embodiments, the first voltage dividing unit further includes a first capacitor C1, and the first capacitor C1 is connected in parallel with the second resistor R2. The first capacitor C1 and the first resistor R1 form a low-pass filter for filtering the input voltage.

[0051] Specifically, the first voltage dividing unit can be additionally provided with a first capacitor C1, and the first capacitor C1 is connected in parallel with the second resistor R2. The first capacitor C1 and the first resistor R1 can form a first low-pass filter. The time constant τ1 of the first low-pass filter is R1*C1, by adjusting the time constant τ1, the stable time of the first voltage VIN+ can be adjusted, that is, the time t3 for the first voltage VIN+ to reach the stable value K3 in the on process of the switch module 10, t3=n2*τ1, n2≥5. In one example, n2=5.

[0052] Please refer to Figure 4 In some embodiments, the second voltage dividing unit further includes a second capacitor C2, and the second capacitor C2 is connected in parallel with the first voltage stabilizing tube D1. The second capacitor C2 and the third resistor R3 form a low-pass filter for filtering the input voltage.

[0053] Specifically, the second voltage dividing unit can additionally include a second capacitor C2, which is connected in parallel with the first voltage stabilizing tube D1. The second capacitor C2 can function as a bypass to avoid the voltage stabilizing value of the first voltage stabilizing tube D1 from being disturbed and fluctuating. The second capacitor C2 can also form a second low-pass filter together with the third resistor R3. The time constant τ2 of the second low-pass filter is R3*C2. By adjusting the time constant τ2, the stabilization time of the second voltage VIN- can be adjusted, that is, the time for the second voltage VIN- to reach the stable value K4 during the on process of the switch module 10 is represented by t1, t1=n1*τ2, n1≥5, and in an example, n1=5.

[0054] Referring to Figure 4 In some embodiments, the first voltage dividing unit further includes a third capacitor C3 connected in parallel with the first resistor R1. The third capacitor C3 and the first capacitor C1 are used to filter the input voltage.

[0055] Specifically, the first voltage dividing unit can additionally include a third capacitor C3 connected in parallel with the first resistor R1. The third capacitor C3 is used to filter and decouple the input voltage Vcc.

[0056] Referring to Figure 4 In some embodiments, the second voltage dividing unit further includes a fourth capacitor C4 connected in parallel with the third resistor R3. The fourth capacitor C4 and the second capacitor C2 are used to filter the input voltage.

[0057] Specifically, the second voltage dividing unit can additionally include a fourth capacitor C4 connected in parallel with the third resistor R3. The fourth capacitor C4 is used to filter and decouple the input voltage Vcc.

[0058] Referring to Figure 7 In some embodiments, the control circuit 100 applied to the photovoltaic disconnector 101 further includes a voltage stabilizing module 40 connected with the voltage dividing module 30. The voltage dividing module 30 is used to divide the voltage of the power supply that has passed through the voltage stabilizing module 40.

[0059] It can be understood that when the control power supply of the control circuit 100 is taken from an external power supply, because the photovoltaic assembly 210 has a large laying area, the power supply cable of the external power supply to the control circuit 100 is relatively long, and there are many power taking nodes on the power supply cable, which can cause the power voltage Vin output by the control power supply to fluctuate greatly. When the control power supply of the control circuit 100 is taken from the photovoltaic assembly 210, because of factors such as light intensity, environmental temperature, maximum power point tracking (MPPT) adjustment of the inverter 220, etc., the power voltage Vin output by the photovoltaic assembly 210 also has a large fluctuation.

[0060] Therefore, the voltage stabilizing module 40 is arranged, and the voltage stabilizing module 40 is connected with the voltage dividing module 30, and specifically can be connected between the circuit input end of the control circuit 100 and the voltage dividing module 30. The voltage stabilizing module 40 can perform voltage stabilizing processing on the power supply voltage Vin to obtain an input voltage Vcc, so that the voltage dividing module 30 can perform voltage dividing processing on the input voltage Vcc. In this way, the problem of unstable power supply voltage Vin can be solved, and overvoltage and the like can be avoided to damage the devices in the circuit.

[0061] In addition to the voltage stabilizing function, the voltage stabilizing module 40 can also be additionally provided with other functions according to actual application conditions. The specific structure of the voltage stabilizing module 40 is described in detail below. Please refer to Figure 7 In some embodiments, the voltage stabilizing module 40 includes a diode D3, a fourth resistor R4, a fifth capacitor C5, and a second voltage stabilizing tube D2. The negative electrode of the diode D3 is connected with one end of the fourth resistor R4, the other end of the fourth resistor R4 is connected with one end of the fifth capacitor C5, the other end of the fifth capacitor C5 is grounded, and the second voltage stabilizing tube D2 is connected in parallel with the fifth capacitor C5. The diode D3 is used for anti-reverse processing of the power supply voltage. The fourth resistor R4 and the fifth capacitor C5 are used for current limiting and filtering processing of the power supply voltage, and the second voltage stabilizing tube D2 is used for voltage stabilizing processing of the power supply voltage to obtain an input voltage.

[0062] Specifically, in the voltage stabilizing module 40, the positive electrode of the diode D3 is connected with the circuit input end, the negative electrode of the diode D3 is connected with one end of the fourth resistor R4, the other end of the fourth resistor R4 is connected with one end of the fifth capacitor C5, the other end of the fifth capacitor C5 is grounded, and the second voltage stabilizing tube D2 is connected in parallel with the fifth capacitor C5. The voltage dividing module 30 is connected in parallel with the fifth capacitor C5.

[0063] The diode D3 can perform anti-reverse processing on the power supply voltage Vin. When the power supply voltage Vin appears a non-positive voltage, the diode D3 can realize effective anti-reverse function due to its own unidirectional conduction characteristic. The fourth resistor R4 and the fifth capacitor C5 constitute a current limiting filter. When the power supply voltage Vin passes through the diode D3 and flows to the current limiting filter, it can ensure that the rear-end circuit avoids large current impact. The fifth capacitor C5 has a large capacitance value, for example, the capacitance value of the fifth capacitor C5 can be in the range of 10-20 µF. In this way, more energy can be stored to ensure the power consumption of the rear-end circuit in abnormal moments.

[0064] The voltage stabilizing value of the second voltage stabilizing tube D2 can be determined according to actual application requirements. The power supply voltage Vin processed by the voltage stabilizing module 40 can be represented by the input voltage Vcc through the selected voltage stabilizing value.

[0065] Thus, the voltage stabilizing module 40 composed of the diode D3, the fourth resistor R4, the fifth capacitor C5 and the second voltage stabilizing tube D2 realizes four functions of anti-reverse, voltage stabilization, current limitation and energy storage.

[0066] The fifth resistor R5 is further connected between the switch control module 20 and the switch module 10. When the first voltage VIN+ is greater than the second voltage VIN-, the control voltage Vout drives the gate of the field effect transistor Q1 via the fifth resistor R5; when the first voltage VIN+ is less than the second voltage VIN-, the gate of the field effect transistor Q1 is discharged to the operational amplifier output terminal of the operational amplifier op1 through the fifth resistor R5. The fifth resistor R5 can suppress the oscillation in the turn-on and turn-off processes of the switch module 10, so that the turn-on and turn-off of the switch module 10 are smoother.

[0067] It can be understood that the field effect transistor Q1 working in the amplification zone is prone to overheat and damage, and even explosion. Therefore, it is necessary to avoid the field effect transistor Q1 from entering the amplification zone, that is, the control voltage Vout needs to be greater than the threshold value of the amplification zone when the field effect transistor Q1 is turned on. The second threshold value K2 is set to be greater than the threshold value of the amplification zone, that is, the first threshold value K1 is also greater than the threshold value of the amplification zone, so as to ensure that the control voltage Vout is greater than the threshold value of the amplification zone when the field effect transistor Q1 is turned on. The voltage of the amplification zone is a parameter of the field effect transistor Q1 itself. In an example, the voltage interval of the amplification zone is 2.4V-3V, and 3V is taken as the threshold value of the amplification zone.

[0068] During the turn-on and turn-off processes of the switch module 10, there is a problem of setting a comparison value. Since there is no digital MCU control, during the process that the input voltage Vcc gradually rises from 0V to the set value K0, the first voltage VIN+ and the second voltage VIN- also gradually rise.

[0069] During this process, if the first voltage VIN+ and the second voltage VIN- cannot be well controlled, the first voltage VIN+ and the second voltage VIN- will appear multiple fluctuation and crossing processes. If crossing occurs, there must be a case that the first voltage VIN+ is greater than the second voltage VIN-, the first voltage VIN+ is less than the second voltage VIN- or the first voltage VIN+ is equal to the second voltage VIN-.

[0070] Due to the alternation of the above three situations, the control voltage Vout also repeatedly appears high level and low level, and the switch module 10 is repeatedly turned on and turned off. Since the input voltage Vcc is still changing at this time, and has not reached the stable value K0, the gate voltage of the field effect transistor Q1 needs to exceed a certain threshold value to enter the saturation region. When the input voltage Vcc is high, the field effect transistor Q1 can be repeatedly turned on and turned off, but when the input voltage Vcc is low, the field effect transistor Q1 enters the amplification region, and it is necessary to avoid the field effect transistor Q1 entering the amplification region.

[0071] First, during the process of the input voltage Vcc rising, to avoid the control voltage Vout outputting high level, the first voltage VIN+ is less than the second voltage VIN- which needs to be kept stable. After the input voltage Vcc reaches a certain threshold value, the first voltage VIN+ is equal to and then greater than the second voltage VIN-, realizing the control voltage Vout from low level to output high level once, avoiding the field effect transistor Q1 entering the amplification region and being repeatedly turned on and turned off during the on process.

[0072] Secondly, during the process of the input voltage Vcc falling, to realize the first voltage VIN+ rapidly falling, reaching the turning point, the first voltage VIN+ is less than the second voltage VIN-, realizing the control voltage Vout from high level to output low level once, avoiding the field effect transistor Q1 entering the amplification region and being repeatedly turned on and turned off during the off process.

[0073] During the process of the input voltage Vcc gradually rising from 0V, since the input voltage Vcc is still changing at this time, and has not reached the stable value K0, the gate voltage of the field effect transistor Q1 needs to exceed a certain threshold value to enter the saturation region. When the input voltage Vcc is high, the field effect transistor Q1 can be repeatedly turned on and turned off, but when the input voltage Vcc is low, the field effect transistor Q1 enters the amplification region, and it is necessary to avoid the field effect transistor Q1 entering the amplification region.

[0074] Therefore, please refer to Figure 4 In some embodiments, the first voltage and the second voltage both increase with the increase of the input voltage, and the increase speed of the first voltage is less than the increase speed of the second voltage before the first voltage is greater than the second voltage.

[0075] It can be understood that the first voltage VIN+ and the second voltage VIN- are both obtained by dividing the input voltage Vcc, and the first voltage VIN+ and the second voltage VIN- both increase with the increase of the input voltage Vcc and are kept after reaching the stable value respectively.

[0076] Due to the alternation of the fluctuation and crossing of the first voltage VIN+ and the second voltage VIN, the switch module 10 will be mis-opened and mis-closed, and will be repeatedly opened and closed. Therefore, in the process of the rising of the input voltage Vcc, to avoid the output of the control voltage Vout being high, the first voltage VIN+ needs to be kept stable before the first voltage VIN+ is less than the second voltage VIN-. After the input voltage Vcc reaches a certain threshold, the first voltage VIN+ is equal to and then greater than the second voltage VIN-, so as to realize the flip of the control voltage Vout from low to high.

[0077] Therefore, before the first voltage VIN+ is greater than the second voltage VIN-, the increasing speed of the first voltage VIN+ is less than that of the second voltage VIN-; after the second voltage VIN+ reaches a stable value, the first voltage VIN+ continues to increase to be greater than the stable value of the second voltage VIN-, so as to realize the flip of the control voltage Vout. As shown in FIG. 4, before the first voltage VIN+ is greater than the second voltage VIN-, the slope of the waveform curve corresponding to the first voltage VIN+ is always less than that of the waveform curve corresponding to the second voltage VIN-. Figure 4

[0078] Please refer to Figure 4 In some embodiments, the product of the resistance value of the first resistor R1 and the capacitance value of the first capacitor C1 is greater than the product of the resistance value of the third resistor R3 and the capacitance value of the second capacitor C2.

[0079] The opening time of the switch module 10 meets the first preset condition, and the first preset condition is t1 < t2 < t3. Wherein, t1 = n1 * τ2, n1 ≥ 5, τ2 = R3 * C4. t2 is the opening time of the switch module 10. t3 is the stable time of the first voltage VIN+ of the non-inverting input end, t3 = n2 * τ1, n2 ≥ 5, τ1 = R1 * C2, then τ1 is greater than τ2, that is, the product of the resistance value of the first resistor R1 and the capacitance value of the first capacitor C1 is greater than the product of the resistance value of the third resistor R3 and the capacitance value of the second capacitor C2.

[0080] In this case, it can be ensured that the increasing speed of the first voltage VIN+ is less than that of the second voltage VIN- before the first voltage VIN+ is greater than the second voltage VIN-, so that the second voltage VIN- is always higher than the first voltage VIN+ before the second voltage VIN- reaches the stable value K4. After the second voltage VIN- reaches the stable value K4 at the time t2, the first voltage VIN+ continues to rise, and exceeds K4 after the time t2, so as to drive the flip to output high, and at the same time, the first voltage VIN+ continues to rise until reaching the stable value K3. In this way, in the opening process, the field effect transistor Q1 is effectively prevented from entering the amplification zone and being repeatedly opened and closed.

[0081] Please refer to​Figure 4 The resistance value of the parallel connection of the first resistor R1 and the second resistor R2 is less than the resistance value of the third resistor R3.

[0082] Specifically, in the process of controlling the circuit 100 from the stable on state to the complete off state, to achieve reliable off, the field effect transistor Q1 also needs to avoid entering the amplification zone, and must be turned off at one time to avoid repeated opening and closing.

[0083] In the off process, the discharge speed of the first voltage VIN+ needs to be greater than the discharge speed of the second voltage VIN-, therefore, the resistance value of the parallel connection of the first resistor R1 and the second resistor R2 needs to be less than the resistance value of the third resistor R3, and meanwhile, considering the energy storage effect of the first capacitor C1, after the resistance values of the first resistor R1, the second resistor R2 and the third resistor R3 are determined, the descending speed of the first voltage VIN+ can be made greater than the descending speed of the second voltage VIN-.

[0084] At time t3, the input voltage Vcc starts to be turned off, at this time the first voltage VIN+ starts to descend, and the descending speed of the first voltage VIN+ is greater than the descending speed of the second voltage VIN-, avoiding the phenomenon that the field effect transistor Q1 cannot be turned off; meanwhile, with the voltage descending, the gate voltage of the field effect transistor Q1 gradually enters the amplification zone, at this time if the current IDS still exists, then the phenomenon of damage to the field effect transistor Q1 caused by turning off will inevitably occur.

[0085] In order to avoid the field effect transistor Q1 entering the amplification zone, the actual off voltage value K5 of the gate of the field effect transistor Q1 at time t4 must be greater than the minimum reliable on voltage value K6 of the field effect transistor Q1, and the minimum reliable on voltage value K6 can be obtained in the corresponding device manual of the field effect transistor Q1; meanwhile, after the field effect transistor Q1 is turned off, the first voltage VIN+ must always be less than the second voltage VIN-. In this way, the first voltage VIN+ and the second voltage VIN- are avoided from crossing twice or multiple times, thereby avoiding the false on and false off of the switch module 10 before and after turning off, and avoiding the damage to the field effect transistor Q1 caused by frequent on and off in the amplification zone.

[0086] Please refer to Figure 4 In some embodiments, the switch module 10 is a field effect transistor Q1, and the stable voltage value of the first voltage regulator D1 is greater than the threshold voltage of the amplification zone of the field effect transistor Q1.

[0087] Please refer to Figure 4 In some embodiments, the switch module 10 is a field effect transistor Q1, and the voltage of the input voltage is greater than the threshold voltage of the amplifier of the field effect transistor Q1 in the case that the voltage division value of the second resistor R2 is greater than the stable voltage value of the first voltage regulator D1.

[0088] Specifically, in the case that the first voltage VIN+ is greater than the second voltage VIN-, the control voltage Vout= input voltage Vcc at this time, the field effect transistor Q1 is turned on, which can be divided into two cases: The first case: the stable voltage value of the first voltage regulator D1 is greater than the threshold value of the amplification zone, and the stable value of the second voltage VIN- is determined by setting the parameters of the first voltage regulator D1. It can be understood that the value of the input voltage Vcc is greater than the stable value of the second voltage VIN-, and in the case that the first voltage VIN+ is greater than the second voltage VIN-, the input voltage Vcc is obviously greater than the threshold value of the amplification zone, and the field effect transistor Q1 will not work in the amplification zone.

[0089] The second case: the stable voltage value of the first voltage regulator D1 is less than the threshold value of the amplification zone, and since the input voltage Vcc determines the first voltage VIN+ through the first resistor R1 and the second resistor R2, at this time, the resistance values of the first resistor R1 and the second resistor R2 need to be considered. It is found through research that in the case that the voltage value of the second resistor R2 is greater than the stable voltage value of the first voltage regulator D1, the input voltage Vcc can be greater than the threshold value of the amplification zone in the case that the first voltage VIN+ is greater than the second voltage VIN-.

[0090] In this way, it is ensured that the field effect transistor Q1 will not enter the amplification zone in the case that the first voltage VIN+ is greater than the second voltage VIN-.

[0091] Referring to Figure 8 The application embodiment also provides a photovoltaic shutdown device 101, which comprises the control circuit 100 applied to the photovoltaic shutdown device 101 according to any one of the above embodiments.

[0092] Referring to Figure 3 The application embodiment also provides a photovoltaic system 200, which comprises the photovoltaic shutdown device 101 according to the above embodiment.

[0093] Specifically, the photovoltaic system 200 comprises the photovoltaic shutdown device 101, a plurality of photovoltaic modules 210, an inverter 220 and a transmitter 230. The control circuit 100 is applied to the photovoltaic shutdown device 101, and the number of the photovoltaic modules 210 is multiple. The photovoltaic shutdown device 101 can be arranged in the photovoltaic system 200 in a series or parallel manner with the photovoltaic modules 210. The transmitter 230 is used for transmitting electromagnetic waves to supply power to the photovoltaic shutdown device 101, and further supply power to the control circuit 100 applied to the photovoltaic shutdown device 101.

[0094] As Figure 3 shown, the multiple photovoltaic modules 210 are connected in series with the inverter 220, and one photovoltaic shutdown device 101 is connected between every two photovoltaic modules 210. As Figure 9As shown, each photovoltaic breaker 101 is connected in parallel with a photovoltaic module 210, and multiple photovoltaic breakers 101 are connected in series with an inverter 220.

[0095] In the control circuit 100, the photovoltaic breaker 101 and the photovoltaic system 200 of the embodiments of the present application, the input voltage Vcc is processed by the voltage dividing module 30, and the hysteresis filter module 50 is further provided. The control voltage Vout is determined by the switching control module 20 according to the input voltage Vcc after voltage dividing and the hysteresis width of the hysteresis filter module 50, so as to control the on-off state of the switching module 10 according to the control voltage Vout. In this way, the switching module 10 is prevented from being repeatedly turned on and off due to voltage oscillation at the turn-on and turn-off moments, precise control of the switching module 10 is achieved, the service life of the switching module 10 is improved, and the reliability and safety of the photovoltaic system 200 are also improved.

[0096] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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. In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified and limited.

[0097] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0098] In the present application, unless specifically stated and limited otherwise, the expression "on" or "under" of a first feature with respect to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Also, the expression "on", "above" and "over" of a first feature with respect to a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. The expression "under", "below" and "underneath" of a first feature with respect to a second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0099] The above disclosure provides many different embodiments or examples for implementing different structures of the present application. For the purpose of simplification, the components and arrangements of specific examples are described in the above. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides various specific examples of processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0100] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "embodiment", "example", "specific example", "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0101] Although the embodiments of the present application have been shown and described above, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations of the embodiments can be made without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A control circuit for a photovoltaic switch, characterized in that, The photovoltaic shut-off device is applied to a photovoltaic system, the photovoltaic system including photovoltaic modules, and the control circuit applied to the photovoltaic shut-off device includes: A switching module, connected to a photovoltaic module, wherein the switching module is a field-effect transistor; The voltage divider module includes a first voltage divider unit and a second voltage divider unit connected in parallel. The first voltage divider unit is used to output a first voltage according to the input voltage, and the second voltage divider unit is used to output a second voltage according to the input voltage. A switch control module is connected to the first voltage divider unit, the second voltage divider unit, and the switch module, respectively. The switch control module is used to output a control voltage based on the comparison result of the first voltage and the second voltage. When the first voltage is greater than the second voltage, the control voltage is equal to the input voltage to turn on the switch module; when the first voltage is less than or equal to the second voltage, the control voltage is zero to turn off the switch module. The hysteresis filter module has one end connected between the switch control module and the switch module, and the other end connected between the first voltage divider unit and the switch control module. When the control voltage is equal to the input voltage, the hysteresis filter module is used to stagger the threshold points for the switch module to turn on and off.

2. The control circuit for a photovoltaic switch as described in claim 1, characterized in that, The first voltage divider unit includes a first resistor and a second resistor. One end of the first resistor is connected to one end of the second resistor, and the other end of the second resistor is grounded. One end of the switch control module is connected between the first resistor and the second resistor. The hysteresis filter module includes a hysteresis resistor, one end of which is connected between the switch control module and the switch module, and the other end is connected between the first resistor and the second resistor; The resistance value of the hysteresis resistor is less than the resistance value of the first resistor.

3. The control circuit applied to a photovoltaic switch as described in claim 2, characterized in that, The hysteresis filter module also includes a hysteresis capacitor, which is connected in parallel across the hysteresis resistor to form a low-pass filter with the hysteresis resistor.

4. The control circuit applied to a photovoltaic switch as described in claim 2, characterized in that, The second voltage divider unit includes a third resistor and a first Zener diode. The third resistor is connected to one end of the first Zener diode, and the other end of the first Zener diode is grounded. One end of the switch control module is connected between the third resistor and the first Zener diode. The third resistor and the first Zener diode are used to divide the input voltage to obtain the second voltage, which is then input to the switch control module.

5. The control circuit for a photovoltaic switchgear according to claim 4, characterized in that, The first voltage divider unit further includes a first capacitor, which is connected in parallel with the second resistor; The first capacitor and the first resistor form a low-pass filter for filtering the input voltage; The second voltage divider unit also includes a second capacitor, which is connected in parallel with the first Zener diode; The second capacitor and the third resistor form a low-pass filter for filtering the input voltage.

6. The control circuit for a photovoltaic switchgear according to claim 5, characterized in that, The first voltage divider unit further includes a third capacitor, which is connected in parallel with the first resistor; The third capacitor is used to filter the input voltage; and / or The second voltage divider unit also includes a fourth capacitor, which is connected in parallel with the third resistor; The fourth capacitor is used to filter the input voltage.

7. The control circuit for a photovoltaic switchgear according to claim 6, characterized in that, The control circuit applied to the photovoltaic switch also includes a fourth resistor, a fifth capacitor, and a second Zener diode. The fourth resistor is connected to one end of the fifth capacitor, the other end of the fifth capacitor is grounded, the fifth capacitor is connected in parallel with the voltage divider module, and the second Zener diode is connected in parallel with the fifth capacitor. The fourth resistor and the fifth capacitor are used to perform current limiting and filtering on the power supply voltage, and the second Zener diode is used to regulate the power supply voltage to obtain the input voltage.

8. The control circuit for a photovoltaic switch as described in claim 7, characterized in that, The control circuit applied to the photovoltaic switch also includes a diode, the negative terminal of which is connected to one end of the fourth resistor; The diode is used to prevent the power supply voltage from being reversed.

9. A photovoltaic switch, characterized in that, Includes the control circuit applied to a photovoltaic switch as described in any one of claims 1-8.

10. A photovoltaic system, characterized in that, Includes the photovoltaic shut-off device as described in claim 9.

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