Research on Fractional Order Modeling and PIλ Control Strategy of V2G Two-Stage Bidirectional Converter

Abstract

With regard to the insufficiency of independent modeling accuracy in V2G two-stage bi-directional converter in the two-stage system of integer order, it is impossible to accurately describe the actual situation of the poor dynamic performance of the classical PI control strategy as well as the lower power transmission efficiency. Based on the fractional calculus theory, the modeling methods based on the fractional, namely, the state space averaging method and the extended description function method are proposed. The integer inductance and capacitance in the system are extended to fractional inductance and capacitance, and the Fourier decomposition in the extended description function method is extended from integer order to fractional order. The joint mathematical model and small signal model of fractional order for V2G two-stage bidirectional converter are constructed, and the fractional order transfer function of the whole system is obtained. Therefore, a fractional PI <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</sup> control strategy for V2G two-stage converter is designed. Finally, a 3kW prototype is built in the laboratory, which verifies the correctness and feasibility of fractional modeling and fractional PI <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</sup> control strategy.