A photovoltaic module intelligent junction box and its control method

Abstract

The invention discloses a photovoltaic module intelligent junction box comprising a main circuit, a voltage detection selection unit, a voltage detection unit, a control unit and a power supply unit.The main circuit comprises an output unit and a plurality of groups of input units. Each input unit comprises a first switch in series connection with a corresponding battery string, and a second switch in parallel connection with the battery string and the first switch; and the control unit is connected to the main circuit and is used to control the opening and closing of each switch. The presentinvention also discloses a control method correspondingly, including a detection method for short-circuit damage judgment of the second switch, which comprises steps of: S11, controlling the switching off of the second switch; S12, detecting the voltage Va across the second switch and the voltage Vcell of the battery string; S13, when Va is smaller than or equal to a first preset value, and Vcellis larger than n*Voc, n is the preset value, and Voc is the open-circuit voltage of a photovoltaic module, judging the second switch to be in the short-circuit damage state; and S14, controlling theswitching off of the first switch. The junction box and the control method of the invention all have the advantages of safety and reliability.

Description

technical field [0001] The invention mainly relates to the technical field of photovoltaic power generation, in particular to a photovoltaic module intelligent junction box and a control method thereof. Background technique [0002] With the development of modern industry, human beings demand more and more energy, and pay more and more attention to environmental pollution, which prompts human beings to develop new energy sources, such as solar energy, biomass energy, wind energy, water energy and geothermal energy, etc. , Among these new energy sources, solar energy, as an inexhaustible, clean, and pollution-free new energy source, has received widespread attention and is one of the major pillars of the future new energy industry. Distributed photovoltaic power generation is close to the user terminal, which can reduce the loss of power transmission and reduce the impact on the power grid. It makes full use of renewable energy and has good environmental friendliness. It is a...

AI Technical Summary

Problems solved by technology

[0004] 1. The junction box of existing photovoltaic modules installs battery string anti-parallel diodes to prevent hot spot effect, while anti-parallel bypass diodes have a large forward conduction thermal resistance and consume a lot of energy, which will cause the module junction box to heat up and overheat. High; and the existing photovoltaic modules will use diode bypass conduction in the hot spot, the hot spot effect battery string is still connected in parallel in the bypass diode circuit, the hot spot effect is still consuming the power generation energy of the battery string, the battery string The interior is still hot;

[0005] 2. The existing photovoltaic module wiring cannot realize remote intelligent shutdown;

[0006] 3. Existing photovoltaic module junction boxes cannot realize over-temperature and fire alarms, and cannot perform corresponding module shutdown processing;

[0007] 4. The existing photovoltaic module junction box cannot realize the fault self-judgment of the switching device. If the bypass diode fails to detect short circuit or open circuit failure in time, it may cause the junction box to continue to heat up and even cause the module to burn out at high temperature;

[0008] 5. None of the existing photovoltaic module junction boxes can monitor the battery string level. Most of the smart junction boxes can remotely monitor the overall voltage of the photovoltaic module; when a photovoltaic module fails, it is generally a failure at the battery string level. The intelligent junction box cannot be detected in time, causing the fault at the battery string level to expand to the fault at the component level before it is discovered

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