Modeling of a Li-ion Battery Energy Storage System using an Optimal Harmonic Number Based Model of DC-DC Converter for More Electric Aircraft

The increase in electrical power requirement in the more electric aircraft (MEA) leads to the deployment of a high energy density battery energy storage system (BESS). In the presented work, a high energy density Lithium Ion (Li-ion) "Li ion phosphate" battery is selected and is designed as per the requirements of MEA. The proposed Li-ion BESS comprises of 5 Li-ion batteries, which are connected in series and integrated with MEA power distribution bus with a bidirectional isolated DC-DC converter as a charger. A Li-ion battery model based on a modified Shepherd curve-fitting with the addition of the voltage polarization term is also investigated in the paper. The modeled Li-ion battery is integrated to the 270 V DC MEA power distribution bus using the optimal harmonic number based harmonic model of DC-DC converter. The values of duty cycle and coupling inductor used in the modeling is selected in order to achieve maximum power transfer and wide range zero voltage switching (ZVS) operation. The harmonic model representation results for different harmonic number are obtained and are compared with the detailed switch model simulation done in MATLAB (R)/Simulink simulation environment.