A fuzzy sliding mode variable structure control method for pwm rectifier when the voltage of the three-phase grid is unbalanced

Abstract

The invention discloses a PWM (Pulse-Width Modulation) rectifier fuzzy sliding mode variable structure control method when the three-phase network voltage is unbalanced, and belongs to the field of power electronics application. The method comprises the following steps of firstly sampling the direct current side voltage of a rectifier; obtaining a rated active power through a PI (Proportional-Integral) controller; sampling the network voltage and the rectifier current, and using a trap filter for performing positive and negative sequence decomposition on the sampling data; listing and writing the power matrix of the rated values by using the rated power conservation principle; obtaining the rated current through a generalized inverse matrix conversion formula; and finally, obtaining a space voltage vector by the fuzzy sliding mode variable structure control method on an electric current loop. The control method has the advantages that the current loop uses the variable structure control, so that the robustness and the dynamic performance of a system can be enhanced; meanwhile, the variable structure coefficient is regulated through fuzzy operation on state points; the adverse influence due to buffeting is reduced; and the stability of the system is improved.

Description

technical field [0001] The invention belongs to the application field of power electronics, and in particular relates to a rectifier, specifically a voltage source PWM rectifier based on fuzzy algorithm and sliding mode variable structure control when the grid voltage is unbalanced. Background technique [0002] With the development of power electronics technology, a PWM rectifier with bidirectional energy flow has appeared to realize bidirectional energy flow. It has the advantages of sinusoidal grid-side current, adjustable power factor, four-quadrant operation, etc., and truly realizes "green power conversion". It has a wide range of applications in many electrical fields. [0003] However, most studies on rectifiers are based on the condition of three-phase grid voltage balance, but the actual grid voltage is not completely balanced. When the grid voltage is unbalanced, the current on the AC side of the rectifier will generate nonlinear harmonics, and the voltage on th...

AI Technical Summary

Problems solved by technology

However, its anti-interference ability is poor and its dynamic response is slow. It is difficult to meet the requirements of the field with high requirements for rectification.

The sliding mode variable structure control has the advantages of strong robustness and fast dynamic response, but the chattering problem of variable structure control will cause the stability of the system to deteriorate

The chattering problem has always restricted the development of sliding mode variable structure control

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