Research On Inverter Parallel Control Technology By DSP2812

It is because the malfunction occurrence of traditional single–supply systemmay lead to system paralysis, so that the parallel redundant inverter power supply hasbeen widely used in many fields. Also due to the absence of signal lines betweeneach inverters of no control interconnection parallel system, it becomes convenientfor the designing, installment and capacity enlargement of the system. Meanwhile, itreduces the current stress of power switching devices and improves the reliabilityand flexibility of the system. Thus, it has become the industry research mainstreamcontemporarily. The key factor of inverter’s successful parallel operation is to solvethe problem whether the output voltage is with the same phase and same frequency.This paper studies on this question with theoretical analysis and experimentalverification.Firstly, it analyzes the output voltage differences influence on active andreactive power under the condition of different output impedances from the parallelconnection equivalent circuit model of the inverter; Discusses the current retrainintendance thus make the output impedance inductive and at the same time deducesthe characteristic equation of power PQ sagging, makes proper improvements andcalculats the coefficients and current restrain inductance value for after modified PQsagging characteristic equation; Analyzes its frequency characteristics of equivalentoutput impedance and the equivalent output impedance after added virtualimpedance according to closed loop transfer function which is deduced by controldiagram of system; Demonstrates circulations under different output impedances;Improves process of digital power calculation; Dissects the main affecting factors forthe output voltage waveform and finally analyzes the common failures of inverters.Secondly, under the simulation of Matlab/Simulink, parallel connectionthree-way inverter as an example, conducts simulation of the parallel system underdifferent parameters, simulation of whether the system has parallel flow of virtual impedance and simulation of the paralleled current sharing effects which areconducted under the input of inverter modules and faulty modules removal.Finally, the system experimental platform is established based on the simulationresults and verifies feasibility of the control method based on the PQ droop ofparallel inverter system.