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The conventional state-of-charge (SoC) estimation methods based on the equivalent circuit model (ECM) integrate all state variables into one augmented state vector. However, the correlations between RC voltages and SoC degrade the stability and accuracy of the estimates. To address this problem, this paper presents an adaptive SoC estimation method based on the split battery model, which divides the conventional augmented battery model into two submodels: the RC voltage submodel and the SoC submodel. Hence, the cross interference between RC voltages and SoC is reduced, which effectively reduces the oscillation in the estimation and improves the estimation accuracy. In addition, the adaptive algorithm is applied on the SoC submodel to improve the system robustness to noise disturbances. A case of a second-order ECM is analyzed and two types of Lithium-ion batteries are employed to verify the universality of the proposed method. Experimental results show that the undesired oscillation is eliminated during the convergence stage and the maximum SoC error is within 1% over a wide SoC range. [ABSTRACT FROM AUTHOR]

To improve reliability and realize electric isolation, an integrated topology of the charger and drive for medium/high-power electric buses is presented in this paper. The proposed integrated topology can solve the voltage matching problem between the power grid and the battery voltage and between the battery voltage and the drive system. The integration can be realized by using the common hardware of the charging system and the drive system, which can reduce the cost and weight of the whole system. To improve the power level, a three-phase combined full-bridge converter based on the magnetic-combination transformer is adopted in the charging system, which has a single-stage power-factor-correction function, electric isolation, and no electrolytic capacitor. To better reflect the integration, the motor drive system adopts a single-stage boost dual-inverter that is the reconfiguration of the magnetic-combination transformer and the 3-H bridge converter in the charging system and few extra components. The drive system has a single-stage boost/buck function, high reliability, and strong fault-tolerant ability. The proposed integrated topology, which can realize a charging function and a driving function, has been analyzed in this paper. Finally, the experimental results verify the feasibility of the integrated topology. [ABSTRACT FROM PUBLISHER]