The Research And Design Of Three-level Rectifier Based On Internal Model Control

In recent years,because of the strong competitive advantage of three-level topology in practicality and control complexity,the research of three-level rectifier and its control technology has gradually become a research hotspot in PWM converter technology.Taking diode clamped three-level rectifier as the research object,in many control methods,the SVPWM control method has prominent advantages and is easy to implement,which has become one of the hot topics.This paper mainly analyzes various control strategies adopted in three level rectifier from the perspective of technology,and improves the traditional double closed loop PI control with internal model control algorithm.The main contents are as follows:The topology of the three level rectifier is analyzed in detail.In view of the requirements of this design,the topology of the diode clamp circuit is determined.The SVPWM control strategy is described in terms of reference vector position judgment,vector synthesis,vector action sequence and action time.According to the traditional principle and mathematical model analysis of the voltage and current double closed loop PI control,the control strategy of the system is optimized and improved with the internal model control.The principle of software phase locked loop in single synchronous rotating coordinate system is analyzed.The positive and negative sequence components are separated by the delay method,and the positive sequence components are obtained to achieve phase locking,which improves the system's anti-interference performance.A small vector adjustment coefficient control method based on charge conservation is adopted to solve the problem of mid point potential balance.The simulation results show that the control strategy optimization,phase locking and neutral point potential balance control are effective and feasible.