Novel MPC control method suitable for single-phase cascade rectifier of direct-current microgrid

Abstract

The invention discloses a novel MPC control method suitable for a single-phase cascade rectifier of a direct-current microgrid. The preceding stage of a main circuit of the cascade rectifier is a single-phase PWM rectifier and a post stage of the same is a Buck circuit; according to the control method, the thought of model predictive control is adopted, key circuit parameters are predicted according to a circuit switching period mathematical model, calculation of a cost function is abandoned, the duty ratio of a switching tube is directly calculated according to a control target, and PWM is combined to achieve switching tube fixed-frequency control. A two-stage circuit structure is adopted, limitation of a single-stage circuit is broken through, the contradiction between transient state and steady state regulation and control of a single-phase rectification circuit during sudden load change is solved, and the double fundamental frequency fluctuation of the outlet voltage of a single-phase PWM rectifier is eliminated. Meanwhile, a novel model prediction control method is adopted, so that the algorithm calculation amount is reduced, and the calculation cost of a circuit control chipis reduced. The circuit structure is simple, the control algorithm is simple and convenient, the outlet voltage can be rapidly recovered when sudden load change happens to the circuit, and the rectifier outlet voltage quality is remarkably improved.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a novel MPC (Model Predictive Control, MPC) control method suitable for a single-phase cascaded rectifier of a DC microgrid. Background technique [0002] In recent years, with the introduction of the concept of "microgrid" and the development of clean energy power generation technologies such as photovoltaic power generation and wind power generation, DC microgrids have been vigorously developed. At present, domestic and foreign research on DC microgrids mainly focuses on the voltage control, protection and distributed power management of the system, and there are few studies on the power quality of microgrids. With the development of industrial technology, the requirements for power quality are getting higher and higher. In order to provide users with high-quality DC power, develop DC power supply technology, and popularize practical projects, it is of great signific...

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Problems solved by technology

The control structure of these MPC control strategies is complex, the algorithm has a large amount of calculation, and it also involves the selection and design of the cost function. The circuit control effect is often directly related to the cost function.

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