Single-phase photovoltaic grid-connected inverter

Abstract

The invention discloses a single-phase photovoltaic grid-connected inverter which mainly comprises a direct current / direct current (DC / DC) voltage converter, a direct current / alternating current (DC / AC) voltage converter, a current and voltage detecting circuit, a controller and a control circuit. The DC / DC part adopts a logic link control (LLC) resonance half bridge to finish conversion of direct current voltage, and a closed loop control circuit for outputting voltage is added, so that the DC / DC no longer outputs constant direct current voltage but the voltage with the steam-bread-shaped waveform and having the same frequency and phase with a power grid, and a resonance inductor and a resonance capacitor in the circuit are designed to effectively reduce switch loss and switch noises. In the DC / AC part, the voltage with the steamed-bread-shaped waveform serves as the input voltage to be connected with a direct current side of the inverter, so that effective inversion of the voltage is achieved, simultaneously voltage difference between two ends of a filter inductor in the inversion circuit is effectively reduced, the output current is smooth, and the harmonic content is reduced. The single-phase photovoltaic grid-connected inverter is small in size, high in efficiency, stable in performance, and easy to implement, and the harmonic content after the inversion is less, and the size of a harmonic suppression circuit is small.

Description

technical field [0001] The present invention relates to the field of single-phase photovoltaic grid-connected inverters, and more specifically, to a single-phase photovoltaic grid-connected inverter. Background technique [0002] With the increasing development of social production, the demand for energy is constantly increasing, and the global energy crisis is becoming increasingly prominent. The fossil energy in the earth is limited and will be exhausted one day. With the reduction of fossil energy, its price will also increase, which will seriously restrict the development of production and the improvement of people's living standards. Renewable energy is an important resource to meet the world's energy needs, especially for our populous country. Among them, solar energy resources are very rich in our country, and its application has a very good prospect. [0003] The core technology of photovoltaic grid-connected power generation system is the grid-connected inverter,...

AI Technical Summary

Problems solved by technology

[0006] In order to overcome the disadvantages of poor power utilization, poor stability and high harmonic content of sinusoidal voltage output after inversion in the prior art single-phase photovoltaic grid-connected inverter, the present invention proposes a single-phase photovoltaic grid-connected inverter, The single-phase photovoltaic grid-connected inverter of the present invention enhances its stability while improving the power utilization rate, and reduces the harmonic content of the grid-connected output current

Images