Improved structure of passivity-based control of battery-supercapacitor hubrid energy storage system

Abstract

Energy storage systems are a topical modern area of research due to the rapid development of renewable energy and electric vehicle construction. Due to the current lack of a source or accumulator of electricity with high specific energy and power, it is being replaced by hybrid electricity storage systems, which consist of separate, complementary sources. Among them, the combination of electrochemical battery – supercapacitor bank is the most common. The paper considers its active configuration, in which both sources are connected to the output network through bidirectional pulse DC-DC converters. The studied hybrid batterysupercapacitor system is a nonlinear dynamic system with multiple inputs, multiple outputs, and two control channels, the operation of which is described by five differential equations. To solve the problem of synthesis of a stable and efficient control system for such an object, the energy approach, namely energy-shaping control has been used. To do this, the studied system is mathematically described as Port-Controlled Hamiltonian system, and two descriptions are compared with different options for choosing the basic vector of the system state. The structural synthesis of the passive control system was performed by the Interconnection and Damping Assignment method. Based on the energy management strategy developed for the system under study, all possible options for introducing interconnections and damping into the passive control system were explored using a computer program developed in the MathCad environment. The effectiveness of the obtained structures of control influence formers on the investigated dynamic system was studied by computer simulation in the Matlab/Simulink environment. According to the results of the research, the variant of control influence former with the best combination of introduced interconnections and damping is formed according to the principle of superposition. To stabilize the voltage values of the output network and the supercapacitor unit set by the control strategy, a proportional-integrated voltage regulator is additionally used, and a sliding regulator between two passive control structures is exploited to limit the allowable battery current. The results of the computer simulation showed the full implementation of the tasks of the energy management strategy, including a smooth increase and limitation of the battery current.