Research Of Single-phase Inverter Parallel Technology Based On DSP

With the increasingly high requirements on the power supply capacity, quality and reliability, parallel inverter power supply system has been more and more widely application and development. In addition, with the advent of digital power supply technology development, the digital control technique and parallel technology is an important research direction of SPWM inverter.This paper is mainly to the research for the single phase inverter parallel operation and its control strategy.First of all, research the single-phase full-bridge inverter and its control method, analyze and establish the mathematical model of the bipolar SPWM inverter, and based on this, to research the double closed-loop control method, derive the closed-loop transfer function of the inverter, and study the closed-loop characteristics.Then, Based on the analysis of single-phase full-bridge inverter equivalent model of two inverter parallel system is established. According to the equivalent model, the reasons of circulation current are analyzed. According to this inverter, the paper proposes a scheme based on power deviation for parallel system control. Using digital phase-locked loop can make the phase of all inverters be the same, controlling the power error can make the magnitude be the same. Through these control strategy, there will be little circulating current, and all the inverters distribute power on, average.Finally, two lkW experimental prototypes are designed which compose the parallel inverter system. Some software modules of digital control system have also been performed such as initialization module, PI algorithm module, SPWM module and detection module. Based on this, the simulation model of parallel inverter system is established by MATLAB. steady-state and transient characteristics of the parallel inverter system are analyzed by simulation. Simulation and experimental are presented to verify the right of the control scheme and the designed parameters.