Output digital modulation circuit and control system of rectifier type high-frequency chain grid-connected inverter

Abstract

The invention discloses an output digital modulation circuit and control system of a rectifier type high-frequency chain grid-connected inverter. The circuit comprises an input voltage U[in], a sinusoidal modulation high-frequency chain inverter, a high-frequency isolation transformer, a synchronous rectifier, a power frequency inverter and an LCL filter. The control system comprises a voltage sensor, a current sensor and a DSP digital controller. The sinusoidal modulation high-frequency chain inverter is composed of four power MOSFETs. The primary side and auxiliary side of the high-frequency isolation transformer are respectively of a single-winding structure. The synchronous rectifier is composed of four IGBTs and an anti-parallel diode. The power frequency inverter is also composed of four IGBTs and an anti-parallel diode. The LCL filter is composed of an inductor L1, an inductor L2 and a capacitor C. The output digital modulation circuit and control system of the rectifier type high-frequency chain grid-connected inverter achieve high-frequency electrical isolation of input and output, have the advantages of being small in size and light in weight and are very suitable for photovoltaic grid-connected generation systems.

Description

technical field [0001] The invention relates to an output digital modulation circuit and a control system of a rectifying high-frequency chain grid-connected inverter, and belongs to the technical field of power electronic converters and their control. Background technique [0002] The increasing depletion of fossil energy requires us to find suitable alternative energy sources. Solar energy is an inexhaustible green energy source. Photovoltaic cell power generation is an effective way to utilize solar energy. The output voltage of photovoltaic cells is greatly affected by weather changes, and its fluctuation range has caused certain difficulties for the effective use of solar power. At present, it is a relatively common method to directly transmit electric energy to the grid through a grid-connected inverter. [0003] If a non-electrically isolated power conversion device is used, due to the capacitance of the photovoltaic cell to the ground, the converter provides a low-i...

AI Technical Summary

Problems solved by technology

If the sinusoidal modulation is performed in the subsequent inverter, the control scheme results in a notched high-frequency DC square wave voltage at the output of the synchronous rectifier, then the notched voltage will have a greater impact on the quality of the inverter output voltage waveform Influence, and, like the second control scheme, all switching devices work at high frequency, and the efficiency is difficult to improve

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