Novel dual-quasi-Z-source five-level inverter grid connection control method based on sliding-mode control

Abstract

The invention relates to a novel dual-quasi-Z-source five-level inverter grid connection control method based on sliding-mode control. The method includes the following steps of (1) construction of amodel, wherein according to a topological structure of a novel dual-quasi-Z-source NPC-type five-level inverter, an average state model of a novel dual-quasi-Z-source network is created; (2) acquirement of an actual state model, wherein a small signal disturbance method is adopted for adding disturbance variables to the average state model of the novel dual-quasi-Z-source network to obtain an actual state model of the novel dual-quasi-Z-source network; (3) acquirement of a sliding-mode surface, wherein a state variable is selected and substituted into the actual state model of the novel dual-quasi-Z-source network to determine the sliding-mode surface; (4) voltage and current control; wherein according to the sliding-mode surface, a through duty ratio is determined, a sliding-mode controller is constructed and then connected with the novel dual-quasi-Z-source five-level inverter, and under the combination with an SPWM algorithm, voltage and current control is carried out on the novel dual-quasi-Z-source NPC-type five-level inverter. Compared with the prior art, the method has the advantages of being high in stability, low in current harmonic and the like.

Description

technical field [0001] The invention relates to the technical field of novel grid-connected inverter control strategies, in particular to a novel dual-quasi Z-source five-level inverter grid-connected control method based on sliding mode control. Background technique [0002] In recent years, with the rapid development of renewable energy such as wind power and photovoltaics, the requirements for the stability, conversion efficiency, and power and voltage levels of grid-connected inverters are also getting higher and higher. The Z-source five-level inverter improves the traditional inverter structure and provides a new inverter topology and theory. The Z-source network topology was first applied to the two-level inverter, making the bridge arm of the inverter pass-through a working state, no need to insert dead time in the modulation algorithm, and improving the inverter efficiency. At the same time, the Z-source The inverter can realize buck-boost conversion without adding...

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Problems solved by technology

For this reason, PI control is widely used, but PI control will cause the system to be unstable, and it is easy to generate current harmonics with large fluctuations.

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