Search

This article proposes a fault-tolerant control method for the battery-supercapacitor (SC) hybrid energy storage system (HESS) based on the cascaded multilevel converter during active dc-side failure (ADCF). When ADCF occurs, the magnitude of the output voltage will be seriously affected because of the decline of the dc-side voltage. Consequently, the system cannot operate normally. To tackle this problem, an auxiliary power loop, which uses the dual-frequency phase-shifted carrier pulsewidth modulation to transfer power between different energy storage units, is added into the HESS. The topology of the HESS and the principle of power transfer during failure operation are introduced. The requirement to the numbers of different types of cells: discharging, charging, and standby, is analyzed mathematically. The SC capacity and the control system designs are given. Finally, the simulation results obtained from MATLAB/Simulink as well as experiments based on a prototype are presented to verify the effectiveness of the HESS and the fault-tolerant control. [ABSTRACT FROM AUTHOR]

Because of its simple structure, high power quality and enhanced output voltage, cascaded multilevel converter (CMC) has been utilized as the main circuit of power conversion system of energy storage system. However, it is difficult to adapt CMC to hybrid energy storage system (HESS) because of the asymmetric power distribution problem. This paper proposes a novel topology for CMC-based HESS, in which, an LC branch is inserted at the end of cascaded H-bridges as a tuned filter, and an odd-harmonic-hybrid-modulation (OHHM) is further proposed to control the harmonic frequency components to transfer power among different energy storage components through the LC branch. The principle of the OHHM technique and the design of the LC branch are analyzed, based on which, a joint energy recovery and SOC balancing system is introduced. The principle and control method of the proposed HESS is verified by both the simulations and experiments. [ABSTRACT FROM AUTHOR]