The Research On Three Phase Inverter Power Parallel Technology Which Based On Novel Compound Control

Because of the development of new energy power generation and independent of grid connected operation and the requirement of high reliability,system scalability and convenience of maintenance of UPS power system,the parallel distributed power supply system of inverter has been widely used,the system has the advantage of high frequency,high power density,system normalization,more conducive to modularization and expansion,it has been widely used in a variety of new energy power generation systems,aerospace power systems,communication power system.In this paper,the control strategy of a single-phase inverter is innovated,and the parallel technology is studied theoretically and experimentally.First of all,the mathematical model under various coordinate systems is analyzed start from the mathematical model of three-phase combined inverter;and the factors affecting the quality of output waveform are explained with emphasis.The corresponding control strategy is selected according to the mathematical model in three-phase coordinates of the inverter,the equipment with special load is took into consideration,and control strategy the corresponding is improved,this paper designs a new type of composite controller to enhance the carrying capacity.A feedforward control is designed in the new composite controller,for improving the quality of output waveform further.According to the equivalent model of three-phase inverter parallel system,the paper calculates active power and reactive power of parallel system.In view of a non-interconnect method for parallel system,this paper uses droop characteristics to adjust the equalization of the inverters in a parallel system,further improves droop characteristic equation,and calculates in detail of selecting the droop coefficients.The dynamic situation of the inverter and the machine is analyzed in detail.Secondly,in the simulation environment,a three-phase combined inverter is analyzed,the new composite control strategy is verified in various working conditions,and the feedforward control is verified with nonlinear load,the parallel inverter dynamic is simulated in detail.This paper builds a simulation model of two three-phase inverter with different physical parameters,and builds the inverter in input and removal finally.Then,the parallel inverter system is designed in detail,including the main circuit,isolation transformer,output filter,and device selection.Hardware circuit design includes AC voltage,current sampling circuit,protection circuit,and over temperature circuit.Software design includes main program and interrupt program.Finally,this paper uses STM32F407ZGT6 as the main control chip,and builds a prototype,and tests a variety of working conditions of the inverter.The correctness of the new composite control strategy and feasibility of feedforward channel are verified.