Photovoltaic grid connected inversion circuit, switch control circuit and control method

Abstract

The invention discloses a photovoltaic grid connected inversion circuit, a switch control circuit and a control method and belongs to the technical field of photovoltaic power generation. When the output voltage of a photovoltaic battery pack is larger than the alternating current output voltage of a power grid, a chopped wave switching tube SWc is not switched on, the current flows to an inferior full-bridge inversion unit through a bypass diode Db, and the full-bridge inversion unit works in an SPWM mode; when the output voltage of the photovoltaic battery pack is smaller than or equal to the alternating current output voltage of the power grid, the chopped wave switching tube SWc works in a high-frequency PWM mode, and the full-bridge inversion unit works at the power frequency. Only one level of a converter unit works at the high frequency at any moment so that the efficiency of a whole machine can be improved; due to the fact that a high-capacity electrolysis direct current capacitor set is not used, a solar photovoltaic power generation system which is small in size, light in weight and low in cost can be obtained.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, and more specifically, to a photovoltaic grid-connected inverter circuit, a switch control circuit and a control method. Background technique [0002] From an environmental point of view, the application of small-scale distributed solar photovoltaic power generation systems in residential electricity is becoming more and more popular. For solar photovoltaic power generation systems, the non-isolated single-phase sine wave inverter topology has advantages in terms of cost, size and efficiency, which makes the non-isolated photovoltaic grid-connected structure have good development prospects. The main circuit of the non-isolated sine wave inverter mainly includes two working parts: one is the boost part used to boost the low voltage from the photovoltaic module array; the other is the high-frequency PWM modulation used for AC connection to the grid or direct load inverter par...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to solve the problems existing in traditional photovoltaic inverters: 1) large switching loss and low efficiency of the whole machine; 2) problems such as large volume, bulky photovoltaic inverter and large power loss due to the use of large-capacity electrolytic capacitor banks; Provided are a photovoltaic grid-connected inverter circuit, a switch control circuit and a control method

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