A Reduced-Sensor Modular Dual Active Bridge-Based Battery Charging System for Electric Vehicles Using an Improved Linear Extended State Observer

Abstract:
Developing an off-board rapid battery charging station is quite challenging since it must handle numerous battery chemistries with varying power requirements while maintaining high power conversion efficiency and small size. Furthermore, numerous modular topologies are widely employed to meet the battery's high power requirements while decreasing voltage and current stress on power switches, permitting the use of low-power rating switches. In such modular architectures, power balance among modules must be ensured to avoid overvoltage/overcurrent. Furthermore, such modular systems require many sensors, raising system costs. The traditional observers commonly used to reduce the sensor number introduce large errors between the actual and estimated system states and possess poor transient performance. To address these shortcomings, this paper proposes an improved extended state observer for modular DAB-based battery charging of electric vehicles. Numerical simulations using MATLAB/Simulink demonstrate the proposed system's robustness against disturbances and show how the transient response of the system is greatly improved.