Research On Fractional Order Modeling And Control Of Single-phase Inverter

Inverter as an important kind of power electronic transform device is widely used in the development of new energy, energy conservation and emission reduction, medical, aerospace and other high-tech fields. Modeling and analysis of single phase inverter are usually based on integer order calculus, regardless of the fractional characteristics of real inductors and real capacitors. Due to the inductor and capacitor as the core part of output low pass filter of the inverter bridge, this approximate will bring a deviation with the real system. Aiming at this problem, the fractional order model of single phase voltage type inverter was carried out in this paper. Then, the differences between integer order model and fractional order model about single phase inverter were compared. The fractional model is more accuracy to simulate the real system. Fractional order controller can get better effect, more flexible than integer order ones to fractional order system.Based on the proterties of fractional order inductor and fractional order capacitor, the fractional order model of single phase voltage type inverter is proposed and analyzed. The influences of orders of fractional order inductor and fractional order capacitor to stability and dynamic characteristics of single phase voltage type inverter have been analyzed detailedly. With the block analysis method, fractional order model is used to design the double closed loop control system, including voltage outer loop quasi proportional resonant control and inductor current inner loop proportional integral control. The inferences of fractional order model and integer order model to double closed loop controller parameters design show the superior of fractional order model. Then, the fractional order double closed loop control has been designed, including voltage outer loop fractional PI?D? control and inductor current inner loop fractional PI? control. Combining chain fractance theory and Matlab/Simulink software, the simulation circuit of fractional order double closed loop control system and integer order ones of single phase inverter are construsted respectibely. The output voltage waveforms refelect the differences of parameters design between fractional order control system and integer order control system. Fractional order controller achieves better dynamic perfermence.The paper introduces the process of fractional modeling. The correctness of theory is verified by the simulation circuits and experiments. The results show that the maxmum percentage error in the integer order model and the fractional order model is 9.38% and 1.56%, respectively. In other words, fractional order model is nearly to the real system and fractional order controller can get better behaviors.