Research And Design Of Three-phase Three-level VIENNA Rectifier

At present,the power electronic devices are widely used in a variety of power conversion occasions,and the consequent harmonic pollution has brought great harm to the power grid.Therefore,it is of great significance to study the PWM rectifier with high power factor and low current harmonic content.The three-phase three-level VIENNA rectifier is a three level neutral point clamped,it has been widely concerned by domestic and foreign experts,and has a high research value because of its advantages such as few switching devices,low voltage stress,high power factor,simple control structure and so on.The main work of this paper is the research and design of three phase three level VIENNA rectifier.Firstly,this paper introduces the history and research status of the three-phase three-level rectifier,the working principle of the circuit topology of single phase and three-phase VIENNA rectifier is deduced theoretically,described the operating characteristics of three-phase VIENNA rectifier under different switching states,and the mathematical model of VIENNA rectifier in three-phase stationary coordinate system,two-phase static coordinate and synchronous rotating coordinates is further studied.Based on the mathematical model of VIENNA rectifier,the control system is designed.The PI control of voltage outer loop is analyzed,in order to overcome the disadvantages of slow dynamic response and large overshoot,the sliding mode variable structure control is introduced into the voltage loop control to improve the anti-interference ability.The feed-forward decoupling controller is designed,and calculating the PI parameters.This paper also introduces the model predictive current control,which has the characteristics of simple algorithm and fast dynamic response.The space vector modulation(SVPWM)algorithm suitable for VIENNA rectifier is analyzed,and a new algorithm based on two level VIENNA space vector modulation algorithm is proposed,this algorithm avoids a large number of trigonometric functions and reduces the computational complexity of the algorithm.For diode clamped three level topology,the unbalance of the neutral point potential will bring a series of problems,in this paper,the mechanism of neutral point potential unbalance is analyzed,and a neutral point potential balance control strategy for space vector modulation is introduced.Finally,the simulation model is built on MATLAB,and the control strategy is verified by simulation.According to the experimental requirements,the hardware circuit and software system of the three-phase VIENNA rectifier are designed,and the experimental prototype is built to verify the effectiveness and feasibility of the control strategy.