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.