Photovoltaic inverter bus capacitance pressure equalization and bus overvoltage protection control circuit and system

Abstract

The invention discloses a photovoltaic inverter bus capacitance pressure equalization and bus overvoltage protection control circuit, which comprises a boosting module, an inversion module, an anode bus, a cathode bus, a bus capacitance group, a capacitance and voltage equalization module and an overvoltage protection module, wherein the boosting module is electrically connected with a photovoltaic array; the inversion module is electrically connected with a municipal electric network; the anode bus and the cathode bus are connected with the boosting module and the inversion module; the bus capacitance group comprises at least one group of serial capacitors, and each group of serial capacitors is connected between the anode bus and the cathode bus in parallel; the capacitance and voltage equalization module is connected between the anode bus and the cathode bus in parallel for equalizing the voltage of each capacitor of the bus capacitance group; and the overvoltage protection module is used for detecting voltage between the cathode bus and the anode bus, and when the voltage exceeds a set value, the voltage is fed back to the boosting module to lower the output voltage of the boosting module. The protection circuit is simple, and can realize capacitance and voltage equalization without complex control circuits, the capacitance and voltage equalization is a self-balancing process, and a hardware protection circuit can carry out high and low voltage isolation, quickly responds to bus voltage and has a reliable protection measure.

Description

technical field [0001] The invention relates to the technical field of photovoltaic inverters, in particular to a photovoltaic inverter bus capacitor voltage equalization and bus overvoltage protection control circuit. Background technique [0002] In the photovoltaic inverter, it needs to be connected to the inverter unit through the DC bus. The DC bus provides high-amplitude pulsating current to the inverter and generates pulsating voltage on the bus. Therefore, capacitors are required to support the DC bus. The bus capacitor mainly absorbs the high-amplitude pulsating current on the DC bus to keep the input voltage fluctuation within the allowable range. At the same time, the bus capacitor acts as a buffer between photovoltaic input power and grid-connected output power to achieve a balance between input energy and output energy. It is a necessary component for decoupling input DC power and output AC power. The reliability of the bus capacitor directly affects the reliab...

AI Technical Summary

Problems solved by technology

In the prior art, the method of directly connecting the same resistors in parallel to the two series capacitors is usually adopted, and the excess energy on the capacitors is consumed through the resistors, thereby suppressing excessive high voltage, but this method cannot achieve equal voltage on the capacitors

[0004] Small and medium power photovoltaic inverters generally adopt a two-stage power topology of boost and inverter. The bus voltage is obtained by boosting the photovoltaic input by the previous step-up circuit. Usually, the bus overvoltage protection is implemented by program software, and lacks corresponding hardware. Protection circuit, in fact, the response speed of software protection is relatively slow

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