Grid-connected inverter and control method thereof

Abstract

The invention discloses a grid-connected inverter and a control method thereof. Key points of the technical scheme are that: the grid-connected inverter consists of six switch tubes, two diodes and two inductors, wherein four of the six switches are in the working frequency mode, the other two switches are in the high frequency mode, and only one switch is in the high frequency mode at moment, so that the switching loss is effectively lowered. In the circuit, a bridge arm is allowed to be connected directly, so that overcurrent is avoided, and high reliability is achieved. In the entire working period, voltages at the two ends of a grounding parasitic capacitor of a photovoltaic system do not contain any high-frequency component, so that the drain current is effectively restrained.

Description

technical field [0001] The invention belongs to a photovoltaic grid-connected inverter and a control method thereof. Background technique [0002] As a renewable energy source with abundant resources and wide distribution, solar energy has great potential for development and utilization. Photovoltaic power generation technology is one of the important ways to realize the effective utilization of solar energy. The non-isolated photovoltaic power generation system removes the power frequency isolation transformer, has the characteristics of small size, low cost and high efficiency, and has great market potential and competitiveness. However, due to the parasitic capacitance between the non-isolated photovoltaic power generation system and the ground, the high-frequency switching action of the photovoltaic grid-connected inverter may cause a large leakage current, which may cause grid-connected current distortion, electromagnetic interference, and may even endanger personal sa...

AI Technical Summary

Problems solved by technology

However, there are two main problems in this improved topology based on the full-bridge circuit: first, when the above-mentioned circuit is working, at least two or more switches work in high-frequency mode, which makes the switching loss larger

Second, since the above circuit structure is derived from a full bridge circuit, the same bridge arm cannot be passed through directly, otherwise there will be overcurrent

However, in practical applications, due to external or internal interference of the circuit, it may cause the wrong operation of the switch drive of the same bridge arm, causing the bridge arm to pass through and generate overcurrent, which will affect the reliability of the system.

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