Assessment of the Overall Efficiency in WPT Stations for Electric Vehicles

Abstract

The on-site assessment of the efficiency of a charging station is not a trivial process and is a topic of discussion for professionals. The efficiency of electric Vehicle Supply Equipment (EVSE), is an important parameter for both the user and the EVSE operator. This paper deals with a particular type of EVSE, using static wireless power transfer (WPT). This paper proposes a clear method to account for the parameters which can affect the correct determination of efficiency, such as in particular the accuracy of the meters and the effect of temperature. This work proposes a method to define the accuracy of the power and efficiency on-site assessment, and is aimed at clarifying that despite distorted waveforms at the charging stations, it is possible to reach a good accuracy in a wide temperature span (expanded uncertainty <0.5% between 5∘C and 40∘C). Analysis initiated from the measurement conditions and the actual waveforms recorded at two WPT EVSEs with differently rated power. This paper paves the way for the possibility of verifying class 0.5 meters on-site, desirable for this type of application. The paper also clarifies that despite the evident presence of voltage and current ripple at the batteries, the weight of the ripple power on the total power is nevertheless lower than 0.1%. Finally, the paper highlights how, for the correct measurement of the ripple, it would be advisable to calibrate the instrumentation in DC and in AC, at a frequency double that of the working frequency of the EVSE coils.

A Measurement Method of Power Transferred to an Electric Vehicle Using Wireless Charging

“…However, the WPT CS transmitter side energy losses are beyond the responsibility of the EV owner and preferably should be excluded from the total supplied energy when calculating the price of the charging transaction. Measurement of energy losses or efficiency of WPT systems was studied and reported extensively in [ 24 , 25 , 26 , 27 , 28 , 29 ]. All these techniques focus on estimating losses using instrumentation for current and voltage measurement at both transmitter and receiver circuits.…”

Modelling and analysis of vienna rectifier for more electric aircraft applications using wide band-gap materials

“…The input current, output current, and output voltage are plotted. The main objective is to identify the suitable WBG device for the Vienna rectifier to improve the system's performance, such as efficiency and power density for the aircraft application [16].…”

Analysis and Design of an S/PS−Compensated WPT System with Constant Current and Constant Voltage Charging

“…Compared with the traditional plug-in charging, WPT technology has the advantages of being safer, more efficient, flexible and convenient [1,2]. Therefore, WPT technology has been widely used in electric vehicle charging [3][4][5], implantable medical devices [6,7], underwater power [8,9], convenient consumer electronics [10,11] and other industrial fields [12][13][14].…”