A method for parallel operation of single-phase full-bridge inverters

Abstract

The invention provides a single-phase full-bridge inverter parallel operation method, comprising the following steps the DC bus bar and the AC bus bar of the full-bridge inverter are arranged in parallel; a current sensor is arranged in front of the filter inductor on the AC side of each inverter; Each inverter has an independent controller. The current sensor is interleaved, the is, the left bridge arm of the odd-numbered inverter and the right bridge arm of the even-numbered inverter or the right bridge arm of the odd-numbered inverter and the left bridge arm of the even-numbered inverter. The invention realizes the parallel operation of the full-bridge inverter with high efficiency and low loss, avoids the current imbalance problem caused by circuit parameter error, sampling error, signal conversion error, controller precision, and the like, and ensures the reliable operation of the converter system.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation and converter control, in particular to a method for parallel operation of single-phase full-bridge inverters. Background technique [0002] Solar energy is one of the most important renewable energy sources, and it has been applied in large-scale centralized photovoltaic power plants and distributed photovoltaic power generation systems; the output point of photovoltaic panels is direct current, and it is necessary to convert direct current into alternating current before photovoltaic power generation is connected to the large power grid. The voltage source inverter that converts DC to AC is a key component in a photovoltaic power generation system; due to its advantages in redundancy and capacity control flexibility, compared with single-phase parallel inverters using a common DC bus and an AC bus Using a single centralized inverter has more application prospects; for the s...

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Problems solved by technology

[0002] Solar energy is one of the most important renewable energy sources, and it has been applied in large-scale centralized photovoltaic power plants and distributed photovoltaic power generation systems; the output point of photovoltaic panels is direct current, and it is necessary to convert direct current into alternating current before photovoltaic power generation is connected to the large power grid. The voltage source inverter that converts DC to AC is a key component in a photovoltaic power generation system; due to its advantages in redundancy and capacity control flexibility, compared with single-phase parallel inverters using a common DC bus and an AC bus Using a single centralized inverter has more application prospects; for the single-inductance full-bridge inverter widely used in industry, under the condition of parallel operation, when the carrier signals of the two full-bridge inverter modules are not When synchronizing, there will be a short-circuit problem in the non-filtering inductance bridge arms of the two full-bridge inverter modules; therefore, it cannot generally be used in the parallel operation of the common AC bus and the common DC bus; in the full-bridge inverter The single-phase grid-connected inverter topology with separated inductors for the two bridge arms of the module can avoid the shoot-through problem during parallel operation; however, there may be circulating current problems in parallel-connected converters in both single-inductor and separated-inductor modes, resulting in The current of the two full-bridge inverter modules is unbalanced, and some severe cases will cause serious current distortion

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