Research On Two Stage Inverter For Renewable Energy Generation

Recently,photovoltaic and fuel cells have become increasingly important and widely used in distribution power generation systems in order to alleviate the problems of environmental pollution and depletion of fossil energy reserves.However,the main characteristic of these energies is the low-output voltage.Hence,a DC–DC converter with a large voltage conversion ratio,to boost low voltage to high voltage,is required as an interface to the main electricity source and the household appliances through a DC–AC inverter.Under this background,the two stage inverter emerged.For renewable energy source applications,a large input pulsating current could reduce their lifetime and even damage the power generation equipment,in order to avoid this situation,this paper presents an interleaved Boost converter with zero current ripples,the operational principle and steady state characteristics of the circuit are analyzed in detail.Based on this topology,by integrating coupled inductors and voltage multiplier techniques,another ripple-free input current modified interleaved boost converter for high step-up applications is presented.Then,simulation models are built in MATLAB/Simulink to verify the correctness of theoretical analysis.By comparing the advantages and disadvantages of the commonly used DC/AC inverter topology,ultimately,the single-phase full bridge inverter circuit is used as the back stage of the studied two-stage inverter,and the realization of SPWM control signal based on DSP is clarified,moreover,double closed loop control is adopted in the inverter to improve its dynamic performance.To research the stability of the studied two stage inverter,the mathematic model of the front stage converter and the back stage inverter is set up,also with input and output impedance function.Then,based on the impedance characteristic and Nyquist Criterion,the stability of the studied cascade system and the effect of dc bus capacitor on stability are analyzed.Finally,an experimental platform based on the studied two stage inverter controlled by TMS320F2812 is established for experimental justification,and the experiments show the correctness of the theoretical analysis.