Design of an efficiently aligned capacitive-coupled electric vehicle charging system

Abstract

In this thesis, a detailed design methodology of a transmitter positioning system are presented to achieve an efficient charging system for electric vehicle applications. Most of the compensation topologies of the capacitive power transfer system, reported in the literature are sensitive to the misalignments between the transmitting and the receiving plates which are not addressed yet. Misalignments affect the resonances in the circuit that decreases the mutual capacitance and power transfer efficiency drops significantly for misalignments of a few mm. In this work, a transmitter positioning system is proposed and designed using Solidworks to mitigate the misalignments between the transmitter and the receiver based on an adaptive algorithm. Based on the design analysis, a prototype is constructed and it is found that the system can achieve an accuracy of 99% in case of axial misalignments and 98% in case of both rotational and axial misalignments. Moreover, in the existing optimization of the capacitive power transfer system methods, only limited system parameters are optimized. In addition, these methods are based on constant frequency, constant input voltage, and constant transfer distance. In this research, a multi-objective optimization is presented considering efficiency and THD as objective functions whereas the input voltage, operating frequency and transfer distance are taken as decision variables. All constraints of the parameter values within the feasible region are considered. Then, a multi-objective optimization algorithm is proposed employing a non-dominated sorting technique with a hybrid single-objective algorithm incorporating genetic algorithm (GA) and ant colony optimization (ACO) algorithm. The proposed algorithm is utilized to optimize the capacitive power transfer (CPT) systems. A comparison of the proposed algorithm with NSGA II algorithm is demonstrated and found that the proposed algorithm improves the cost of the objective functions and explore a more extensive area and reduces the number of iterations required to reach the final Pareto-front. This thesis is a pioneering work on designing an efficient CPT system in case of misalignments and can provide engineering decisions given the requirement of a particular charging station.