Cost-Efficiency Optimization of Ground Assemblies for Dynamic Wireless Charging of Electric Vehicles

Abstract

Dynamic wireless power transfer (DWPT) allows electric vehicles (EVs) to be charged while in motion. However, high cost and efficiency concerns limit the widespread adoption of DWPT. A ground assembly (GA) accounts for most of the system cost since it is implemented on a significant portion of the road. This article proposes a cost-efficiency optimization algorithm to determine the optimum design of a DWPT transmitter (Tx) pad. Elongated rectangular pads are considered a compromise between cost and efficiency. An optimization methodology is put forward to maximize Tx pad efficiency while minimizing GA cost over a selected road. The optimum design allows constant power transfer inside a selected rated power zone while considering EV lateral misalignment as a random variable. Main cost factors are accounted for, including the cost of the pad coil Litz wire and ferrite material and Tx power electronics and compensation network. Particle swarm optimization allowed the number of finite element analysis simulations to be reduced by intelligently selecting test designs. Statistical analysis is applied to understand the impact of different variables on the final design and the interdependence between variables. Additional analyses are conducted to evaluate the impact of different DWPT aspects, including the wire gauge, probability density of the misalignment variable, multilayer coil design, and capacitor cost modeling. The algorithm is used to design a 3.7-kVA Tx pad with respect to the SAE J2954 receiver test stand VA WPT1/Z1. The optimization Pareto fronts illustrate the family of optimum designs, while the chosen 3.7-kVA pad offers the statistical expected value of pad efficiency as 96%, GA per meter cost of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\$ $ </tex-math></inline-formula> 1004, and an optimum pad length of 1.75 m. The 3.7-kVA optimized pad is manufactured and tested for several operating conditions verifying the simulation results.