Study Of The Parallel Inverter System Based On DSP

The parallel of inverters can expand capacity and realize redundancy in power supply system.It greatly improves the power system's flexibility,and the system's volume and weight can be remarkably reduced,which means higher reliability,lower cost.So it is now considered as one of the most important research in the field of inverter technology.Presently,with the rapid development of information technology,more and more attention is paid to the digital control and parallel control for inverter systems.This dissertation focuses on the research of parallel operation control system about inverters,designs a parallel operation control system about inverters,which was base on DSP.First,the paper develops mathematical model about the parallel inverter system,circulating current characteristics of parallel system,distribution control of distortion power are also proposed.Based on it after the model is proposed including sharing current control,parallel control strategy a reliable solution of restraining loop current(the P-Q droop method) is designed.The P-Q droop method calculates the active power and reactive power of inverter,which determines the adjusted values of frequency and amplitude,then adjusts SPWM judging by the values,So that the output of inverter power to be adjusted,the parallel system can be stable and reliable.The key of the P-Q droop method is such realization of power regulation as power calculation and regulation.The very important question of system parallel is how fast and accurate get the active power and reactive power,to calculate the Power exactly, Power theory is full analyzed and some formulas of power calculation are achieved, takes into account the requirements of the system,the system uses a two-table method of calculation.The droop coefficients are discussed in order to improve the regulation precision and dynamic response.At the part of the system control,with the load current treated as a measurable disturbance input,a mathematical model is established for inverter,and an inverter controller composed of voltage-loop and current-loop was introduced.Base on double-loop control principle,further analysis of full digital control mode and design parameters of digital voltage regulator,also use MATLAB simulation to prove the stability of system.At the same time,this article also parallel to the inverter power system of hardware and software design.