A Hybrid Control Strategy for VIENNA Rectifier

Abstract

In this paper, a hybrid control strategy of VIENNA rectifier is proposed. The nonlinear mathematical model of VIENNA rectifier in synchronous rotating coordinate system is established, and double closed-loop control strategy, i.e., voltage outer loop using sliding mode control strategy, current inner loop using composite PI control strategy, is adopted. Using sliding mode control theory, sliding mode control law of VIENNA rectifier is derived. Aim at neutral-point voltage imbalance for three-level rectifier, selecting act time of redundancy small vector (include positive vector and negative vector) by judge the direction of the three-phase input current, and then maintain a balance of the neutral-point voltage. Simulation model is established in the Matlab7.1/Simulink environment, hybrid control strategy and traditional dual-PI control strategy are compared, and simulation results show the proposed hybrid control strategy is better than traditional dual-PI control strategy. A 1.6KW experimental prototype is build, and it achieves the desired effect. The results show the proposed hybrid control strategy has lots of advantages, such as better robustness, better dynamic performance, relatively simple parameters setting, and so on. It can solve the traditional PI control strategy’s shortcomings, such as relatively poor of anti-jamming performance, sensitive to the PI control parameters.