Photovoltaic micro-inverter based on secondary-side reference current reconstruction, control system and control method

Abstract

The invention discloses a photovoltaic micro-inverter based on secondary-side reference current reconstruction, a control system and a control method. A topological structure of a staggered flyback laser photovoltaic micro-inverter based on the secondary-side reference current reconstruction is adopted. The control system comprises the staggered flyback laser photovoltaic micro-inverter based on the secondary-side reference current reconstruction, a direct current voltage and current sampling module, a driving circuit, a secondary-side pulse current sampling module, an alternating current sampling and phase locking module and a signal processing unit. The control method is an indirect control method approximate to grid-connected current direct control, primary-side reference current based on the secondary-side reference current reconstruction is adopted to control connection and disconnection of a primary-side switching tube of a flyback converter, and the control method effectively avoids the problem of slow control response, low tracking accuracy and the like in a direct control method, can guarantee same frequency and same phase of output current and public power grid voltage, reduces total harmonic distortion of grid-connected current substantially, and improves output power quality.

Description

technical field [0001] The invention relates to a photovoltaic micro-inverter, a control system and a method based on secondary-side reference current reconstruction. Background technique [0002] The continuous growth of the world's energy demand makes the use of renewable energy, especially photovoltaic power generation, gradually receiving more and more favor. In recent years, the widespread acceptance and in-depth research of photovoltaic building integrated systems and microgrid systems have further enhanced the practicability of photovoltaic power generation systems. Integrated to feed AC current directly to the utility grid. Compared with the traditional centralized photovoltaic grid-connected inverter, the micro-inverter has the advantages of maximum power point tracking of a single module, low DC voltage, flexible expansion, and plug-and-play. Injecting high-quality sinusoidal AC current with the same frequency and phase into the grid, performing efficient maximum...

AI Technical Summary

Problems solved by technology

However, the right-half s-plane zero in the transfer function of the flyback converter from the control to the output current in the continuous conduction mode not only limits the system bandwidth, but also affects the tracking performance of the controller to the output grid-connected current

In the indirect control primary current control scheme, open-loop control is used from the primary current to the output grid-connected current, and the control of the grid-connected current is realized through the control of the primary current, thus fundamentally eliminating the direct control of the grid-connected current However, the double inner loop control structure not only increases the complexity of the control system, consumes more controller resources, but also is not conducive to system stability

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