A three-phase micro-inverter with high efficiency and wide load range and its control method

Abstract

The invention discloses a high-efficiency wide-load-range three-phase micro-inverter and a control method thereof. The high-efficiency wide-load-range three-phase micro-inverter includes a front stage DC-DC converting module used for transmitting electric energy output by a photovoltaic assembly and tracking the maximum power point of the photovoltaic assembly; a middle-stage quasi-third harmonic injection circuit used for injecting AC current meeting power grid connection condition obtained through combination of inverted six-pulse DC current output by the front-stage circuit and quasi-triangular wave output by said circuit; a rear-stage bridge-type inverting circuit, filtering circuit and power grid used for performing inversion on current output by a power optimizing module, filtering the current obtained through combination of the inverted current and the quasi-triangular wave output by the quasi-third harmonic circuit through the filtering circuit and injecting the current into the power grid. The invention also discloses methods for analyzing and designing the quasi-third harmonic injection circuit and extracting ad controlling quasi-third harmonic wave injection current reference signals. The three-phase micro-inverter has characteristics of being simple in structure, high in converting efficiency and small in size.

Description

technical field [0001] The invention relates to a three-phase micro-inverter with high efficiency and wide load range and a control method thereof. Background technique [0002] With the excessive consumption of traditional primary energy and the continuous growth of people's demand for electricity, the utilization of renewable new energy is becoming more and more important. Photovoltaic power generation has developed rapidly due to its advantages of being clean, non-polluting to the environment, inexhaustible, and not subject to geographical restrictions. [0003] At present, photovoltaic grid-connected inverters mainly include centralized inverters, string inverters and micro-inverters. In the small power range of 150W to 300W, the micro-inverter has the advantages of high efficiency, convenient installation, and flexible system expansion, and has been more and more applied in the field of distributed photovoltaic power generation in residential and commercial areas. At ...

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Problems solved by technology

It is also a method to combine three single-phase micro-inverters with three phases A, B, and C to form a three-phase micro-inverter, but in order to achieve power balance, the utilization of some micro-inverters may be affected. Therefore, it is necessary to propose a new high-efficiency three-phase micro-inverter and its control method to reduce power loss and improve the working efficiency of the micro-inverter

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