Photovoltaic intelligent junction box test circuit and control method

Abstract

The present invention discloses a photovoltaic intelligent junction box test circuit and control method, including a power circuit and a FLASH test circuit; the power circuit includes an input capacitor C21, a freewheeling diode D21 and an output capacitor C22, the input capacitor C21 is connected in parallel with a photovoltaic module, the positive electrode of the photovoltaic module is connected to a first output terminal, the negative electrode of the photovoltaic module is connected to a second output terminal, and the output capacitor C22 is connected in parallel with the freewheeling diode D21; a switch tube Q21 is connected between the positive electrode of the photovoltaic module and the first output terminal or between the negative electrode of the photovoltaic module and the second output terminal, and the switch tube Q21 is a power MOS tube and is driven by the FLASH test circuit. The photovoltaic intelligent junction box test circuit and control method provided by the present invention can ensure the reliable operation of the FLASH test, and have the characteristics of good safety, high reliability and fast response speed.

Description

Technical Field

[0001] The present invention relates to a photovoltaic test circuit and a control method, and in particular to a photovoltaic intelligent junction box test circuit and a control method. Background Art

[0002] In recent years, there have been many technical solutions for smart photovoltaic junction boxes, with the themes of optimizing and improving photovoltaic power generation efficiency, improving photovoltaic system fire response mechanisms such as shutdown functions, etc. At present, photovoltaic smart junction boxes, which are of great value in installation and maintenance, have three main functions.

[0003] 1. MPPT function: Through the coordination of software and hardware, each solar panel is equipped with maximum power tracking technology and control devices. This technology can maximize the reduction of power generation efficiency of the power station caused by the characteristics of different solar panels in the solar panel array, reduce the impact of the "barrel effect" on the efficiency of the power station, and greatly improve the power generation efficiency of the power station. From the test results, the maximum system power generation efficiency can even be increased by 47.5%, which increases the investment income and greatly shortens the investment payback period.

[0004] 2. Intelligent shutdown function for abnormal conditions such as fire: When a fire occurs, the software algorithm built into the junction box cooperates with the hardware circuit to determine whether there is an abnormality within 10 milliseconds, and actively cuts off the connection between each battery panel, reducing the voltage of 1500V to about 30V, which is acceptable to the human body, to ensure the safety of firefighters.

[0005] At present, the main methods for testing smart junction boxes are: (1) first perform a flash test and then install the smart junction box; (2) physically short-circuit the main circuit switch tube for testing. These two methods are costly and have low operability.

[0006] How can photovoltaic smart junction boxes truly meet the pain points and difficulties of the photovoltaic market? It is necessary to find the best balance in terms of electrical functions of the junction box, service life of electronic components, cost of the smart junction box and investment returns. However, the current Flash test of smart junction boxes is very complicated and inefficient, which brings great labor costs and urgently needs to be improved. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a photovoltaic intelligent junction box test circuit and control method, which can ensure the reliable operation of FLASH test and has the characteristics of good safety, high reliability and fast response speed.

[0008] The technical solution adopted by the present invention to solve the above technical problems is to provide a photovoltaic intelligent junction box test circuit, including a power circuit and a FLASH test circuit; the power circuit includes an input capacitor C21, a freewheeling diode D21 and an output capacitor C22, the input capacitor C21 is connected in parallel with the photovoltaic component, the positive electrode of the photovoltaic component is connected to the first output terminal, the negative electrode of the photovoltaic component is connected to the second output terminal, and the output capacitor C22 is connected in parallel with the freewheeling diode D21; a switch tube Q21 is connected between the positive electrode of the photovoltaic component and the first output terminal or between the negative electrode of the photovoltaic component and the second output terminal, the switch tube Q21 is a power MOS tube, and the power MOS tube is driven by the FLASH test circuit.

[0009] Furthermore, the negative electrode of the photovoltaic module is connected to the drain of the switch tube Q21, the source of the switch tube Q21 is connected to the second output terminal, the cathode of the freewheeling diode D21 is connected to the first output terminal, the anode of the freewheeling diode D21 is connected to the source of the switch tube Q21, and the base of the switch tube Q21 is connected to the FLASH test circuit.

[0010] Furthermore, the FLASH test circuit includes a switch tube Q1, a switch tube Q2, a diode D1, a diode D2 and a diode D3, the source of the switch tube Q1 is connected to the positive electrode of the driving power supply through a resistor R1, the anode of the diode D3 is connected to the source of the switch tube Q1, the cathode of the diode D3 is connected to the base of the switch tube Q21, the drain of the switch tube Q1 is connected to the ground, and the anode of the diode D1 is connected to the CPU The output end of the IO port is connected, the cathode of the diode D1 is connected in series with the resistor R3 and then connected to the base of the switch tube Q1, the anode of the diode D2 is connected to the positive electrode of the photovoltaic component, the cathode of the diode D2 is connected in series with the resistor R4 and then connected to the cathode of the voltage-stabilizing diode ZD1, the anode of the voltage-stabilizing diode ZD1 is connected to the base of the switch tube Q2, the cathode of the diode D2 is grounded through the capacitor C1, a resistor R5 is connected between the base and drain of the switch tube Q2, the drain of the switch tube Q2 is connected to the ground, the source of the switch tube Q2 is connected to one end of the capacitor C2, the other end of the capacitor C2 is connected to the base of the switch tube Q1, and is connected to the positive electrode of the driving power supply through the resistor R2.

[0011] In order to solve the above technical problems, the present invention also provides a control method for the photovoltaic intelligent junction box test circuit, which includes the following steps: S1) when the photovoltaic intelligent junction box is powered on, the FLASH enable prohibition value in the EEPROM is detected. If the FLASH enable prohibition value is 0, the PWM output is turned on through the CPU IO port output end, and the main circuit power MOS tube is quickly turned on through a software method; S2) after the power-on time exceeds the Flash device test time, the PWM output is turned off, and the CPU IO port output end is set to a high level, thereby turning off the hardware Flash test circuit; S3) when it is detected that the power-on operation time of the photovoltaic intelligent junction box has exceeded the aging time of the junction box, the FLASH enable prohibition value is set to 1 and written into the EEPROM, so that the FLASH test circuit is immediately turned off after the photovoltaic intelligent junction box is powered on next time.

[0012] Compared with the prior art, the present invention has the following beneficial effects: the photovoltaic intelligent junction box test circuit and control method provided by the present invention can charge the capacitor at the moment of power-on, can conveniently open and close the power MOS tube of the main circuit, provide a circuit for Flash test, ensure that the FLASH test operates reliably and the actual operation is safe and reliable, and at the same time the hardware circuit ensures that the input voltage of the photovoltaic component is greater than a certain value before the main circuit MOS is turned on to avoid potential safety hazards; it has the characteristics of good safety, high reliability, fast response speed, low cost and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the photovoltaic intelligent junction box test circuit of the present invention.

[0014] Figure 2 This is a schematic diagram of a FLASH test circuit for a photovoltaic smart junction box in an embodiment of the present invention;

[0015] Figure 3 is another schematic diagram of a FLASH test circuit for a photovoltaic smart junction box in an embodiment of the present invention;

[0016] Figure 4 It is a control flow chart of a photovoltaic intelligent junction box test circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of the photovoltaic intelligent junction box test circuit of the present invention.

[0019] See also Figure 1The photovoltaic intelligent junction box test circuit provided by the present invention is characterized in that it includes a power circuit and a FLASH test circuit; the power circuit includes an input capacitor C21, a freewheeling diode D21 and an output capacitor C22, and a switch tube Q21 is connected between the positive electrode of the photovoltaic component and the first output terminal or between the negative electrode of the photovoltaic component and the second output terminal, and the switch tube Q21 is a power MOS tube, and the power MOS tube is driven by the FLASH test circuit.

[0020] The input capacitor C21 is connected in parallel with the photovoltaic component, the positive electrode of the photovoltaic component is connected to the first output terminal 1-1, the negative electrode of the photovoltaic component is connected to the drain of the switch tube Q21, the source of the switch tube Q21 is connected to the second output terminal 1-2, the cathode of the freewheeling diode D21 is connected to the first output terminal 1-1, the anode of the freewheeling diode D21 is connected to the source of the switch tube Q21, and the output capacitor C22 is connected in parallel with the freewheeling diode D21. This is just a circuit breaker loop, and it can also be an optimizer circuit. The main loop MOS can also be in the positive loop.

[0021] Reference now Figure 2In the FLASH test circuit, one end of the resistor R1 is connected to the positive electrode Vdrive+ of the driving power supply, and the other end is connected to the source of the switch tube Q1. The anode of the diode D3 is connected to the source of the switch tube Q1, and the cathode of the diode D3 is directly connected to the base of the switch tube Q21. The drain of the switch tube Q1 is connected to the ground. The CPU IO port output terminal PA1 is connected to the anode of the diode D1. The cathode of the diode D1 is connected to the base of the switch tube Q1 after being connected in series with the resistor R3. The positive electrode PV+ of the photovoltaic module is connected to the anode of the diode D2. The cathode of the diode D2 is connected to the cathode of the voltage-stabilizing diode ZD1 after being connected in series with the resistor R4. The anode of the voltage-stabilizing diode ZD1 is connected to the base of the switch tube Q2. One end of the capacitor C1 is connected to the cathode of the diode D2, and the other end is connected to the ground. One end of the resistor R5 is connected to the base of the switch tube Q2, and the other end is connected to the drain of the switch tube Q2. The drain of the switch tube Q2 is connected to the ground. The source of the switch tube Q2 is connected to one end of the capacitor C2, and the other end of the capacitor C2 is connected to the base of the switch tube Q1; the function of the capacitor C2 is to provide a delay to ensure that the hardware automatically closes the Flash test circuit only after the Flash test is completed. The voltage-stabilizing diode ZD1 can realize the start-up voltage to be several volts lower than the component open-circuit voltage before turning on the Flash test circuit. Its function is to ensure that the FLASH circuit will not be triggered during the actual operation of the smart junction box. The voltage-stabilizing diode ZD1 can also be a TVS tube. The switch tubes Q1 and Q2 are not limited to MOS tubes, but can also be triodes. The capacitor C1 provides sufficient driving voltage for the switch tube Q2 to ensure that the switch tube Q2 is always turned on during the FLASH test, so that the switch tube Q1 is always turned off, and the switch tube Q1 outputs a high level.

[0022] Reference now Figure 3 , Figure 3 The circuit is Figure 2 Another circuit implementation method, the advantage of this circuit is that it has fewer components, but the disadvantage is that the subsequent stage must have a power loop MOS driver circuit, such as Anma's IR1168STRPBF MOS driver circuit, ADI's ME9926 CEM9926 driver circuit, MICR's T427E TC4427EOA dual high-speed power MOSFET driver, etc. Figure 2The Flash test circuit can directly drive MOS, or it can be connected to the power loop MOS tube drive circuit; the positive electrode PV+ of the photovoltaic module is connected to the anode of the diode D4, the cathode of the diode D4 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to the ground. The cathode of the diode D4 is also connected in series with the resistor R6 and then connected to the cathode of the voltage regulator diode ZD2. The anode of the voltage regulator diode ZD2 is connected to the source of the switch tube Q3, and the anode of the diode D6 is also connected to the source of the switch tube Q3. The cathode of the diode D6 is connected to the base of the switch tube Q21 through the MOS drive circuit; CPU The IO port output terminal PA1 is connected to the anode of the diode D5, and the cathode of the diode D5 and the resistor R7 are connected in series and then connected to the base of the switch tube Q3; the positive electrode of the driving power supply Vdrive+ is connected in series with the resistor R8 and then connected to the base of the switch tube Q3; the drain of the switch tube Q3 is connected to the ground, and the resistor R9 and the capacitor C4 are connected in parallel and are respectively connected to the base and drain of the switch tube Q3. The function of the capacitor C4 is to provide a delay to ensure that the hardware automatically closes the Flash test circuit only after the Flash test is completed. The function of the voltage regulator diode ZD2 is to ensure that the FLASH circuit will not be triggered during the actual operation of the smart junction box. The capacitor C3 provides sufficient energy for the main loop MOS tube drive.

[0023] Reference now Figure 4 , the control flow chart is that the program starts the timer first, reads the EEPROM FLASH enable and disable value, and immediately turns off the PWM output when the value is 1, sets the IO port PA1 to a high level, turns off the hardware FLASH test circuit, and turns on the PWM output when the FLASH enable and disable value is 0. This is only for some CPUs with fast startup time, and the software can also quickly realize the opening of the main circuit power MOS. For CPUs with slow response speed, the PWM output can be turned off, and the switch tube Q21 is turned on by hardware. When the power-on exceeds the Flash device test time (usually about 20ms), the PWM output is turned off, the PA1 output is set high, the hardware Flash circuit is turned off, and then other parts of the program are run. When the program running time exceeds 8 hours (not limited to 8 hours, it can be longer than the aging time of the junction box) and the EEPROM FLASH enable and disable value is 0, the EEPROM FLASH enable and disable value is set to 1 and written to the EEPROM to ensure that the next Flash test circuit is directly turned off after the program runs.

[0024] The photovoltaic intelligent junction box test circuit and control method provided by the present invention effectively solve the problem of FLASH test of photovoltaic module intelligent junction box, and can realize the same simple and convenient test as ordinary photovoltaic junction box, simple operation and high efficiency. It charges the capacitor at the moment of power-on, and then turns on the main circuit MOS tube to provide a circuit for Flash test. After turning on the MOS tube for a certain period of time, the hardware and software will turn off the FLASH test part drive output, ensuring that the Flash test circuit only works during the FLASH test, ensuring safe and reliable on-site operation, and having the characteristics of good safety, high reliability and fast response speed.

[0025] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the definition of the claims.

Claims

1. A photovoltaic intelligent junction box test circuit, characterized in that: It includes a power circuit and a FLASH test circuit; the power circuit includes an input capacitor C21, a freewheeling diode D21 and an output capacitor C22, the input capacitor C21 is connected in parallel with the photovoltaic component, the positive electrode of the photovoltaic component is connected to the first output terminal, the negative electrode of the photovoltaic component is connected to the second output terminal, and the output capacitor C22 is connected in parallel with the freewheeling diode D21; a switch tube Q21 is connected between the positive electrode of the photovoltaic component and the first output terminal or between the negative electrode of the photovoltaic component and the second output terminal, the switch tube Q21 is a power MOS tube, and the power MOS tube is driven by the FLASH test circuit; The negative electrode of the photovoltaic module is connected to the drain of the switch tube Q21, the source of the switch tube Q21 is connected to the second output terminal, the cathode of the freewheeling diode D21 is connected to the first output terminal, the anode of the freewheeling diode D21 is connected to the source of the switch tube Q21, and the base of the switch tube Q21 is connected to the FLASH test circuit; The FLASH test circuit includes a switch tube Q1, a switch tube Q2, a diode D1, a diode D2 and a diode D3. The source of the switch tube Q1 is connected to the positive electrode of the driving power supply through a resistor R1, the anode of the diode D3 is connected to the source of the switch tube Q1, the cathode of the diode D3 is connected to the base of the switch tube Q21, the drain of the switch tube Q1 is connected to the ground, and the anode of the diode D1 is connected to the CPU The output end of the IO port is connected, the cathode of the diode D1 is connected in series with the resistor R3 and then connected to the base of the switch tube Q1, the anode of the diode D2 is connected to the positive electrode of the photovoltaic component, the cathode of the diode D2 is connected in series with the resistor R4 and then connected to the cathode of the voltage-stabilizing diode ZD1, the anode of the voltage-stabilizing diode ZD1 is connected to the base of the switch tube Q2, the cathode of the diode D2 is grounded through the capacitor C1, a resistor R5 is connected between the base and drain of the switch tube Q2, the drain of the switch tube Q2 is connected to the ground, the source of the switch tube Q2 is connected to one end of the capacitor C2, the other end of the capacitor C2 is connected to the base of the switch tube Q1, and is connected to the positive electrode of the driving power supply through the resistor R2.

2. A control method for a photovoltaic intelligent junction box test circuit as claimed in claim 1, characterized in that: The steps include: S1) When the photovoltaic intelligent junction box is powered on, the FLASH enable / disable value in the EEPROM is detected. If the FLASH enable / disable value is 0, the PWM output is turned on through the CPU IO port output end, and the main circuit power MOS tube is quickly turned on through a software method; S2) After the power-on time exceeds the Flash device test time, the PWM output is turned off, and the CPU IO port output is set to a high level, thereby turning off the hardware Flash test circuit; S3) When it is detected that the power-on operation time of the photovoltaic smart junction box has exceeded the aging time of the junction box, the FLASH enable prohibition value is set to 1 and written into the EEPROM, so that the FLASH test circuit is immediately turned off the next time the photovoltaic smart junction box is powered on.

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