Research On Boundary-Conduction-Mode Based Single Phase Inverter With Dual-Channel Interleaving Control

Inverter is the essential part of new energy distributed generation system,so it is of great significance for the development of new energy to improve the conversion efficiency and power density of inverter and reduce its cost.With the advantages of high efficiency and power density,low cost and fast current response,the inverter which inductor current is controlled in boundary conduction mode(BCM)has attracted more and more attention and researches.In order to further improve performance of the inverter,the key problems such as the zero-crossing current distortion and the large current ripple of inductor have been studied systematically in this thesis.Understanding correctly the working principles and characteristics of BCM inverter is the premise to optimize its performance.This thesis describes the working principles of the inverter when unipolar modulation and bipolar modulation are adopted respectively,explains the advantages of unipolar modulation,and introduces the control block diagram and the main parameters design method of single-channel structure inverter.According to simulation and experimental results,the key defects of BCM inverter are pointed out.It is very important to suppress the current distortion near the zero-crossing point for improving the quality of output current.The control difficulties near the zero-crossing point in this thesis are analyzed from mathematical and physical aspects.The advantages and disadvantages of traditional solutions are compared.On this basis,a hybrid modulation scheme with unipolar and discontinuous bipolar is proposed.Simulation and experimental results show that proposed modulation scheme can not only suppress current distortion near the zero-crossing point,but also reduce the conduction loss.In order to further improve power density and the quality of output current,interleaving control strategy of dual-channel structure inverter is studied.This thesis introduces the circuit structure and operating characteristics of dual-channel interleaving control,and establishes the evaluation indexes of interleaving performance.Based on this,control principles and working performance of open-loop control,cross-coupled master-slave control,and PLL-based closed-loop interleaving control are analyzed respectively.Results show that the working performance of PLL-based closed-loop interleaving control which works in master-slave mode is preferred.