A High Gain Observer Design For Wireless Power Transfer Charger For BEV

This paper addresses the design of a high gain observer for a Wireless Power Transfer (WPT) charger for Battery Electric Vehicle (BEV). Firstly, an overview of the studied system is given. Secondly, a classical circuit of a WPT charger and its equivalent mathematical model is presented. Thirdly, the high gain observer is designed for the studied system. It should be noted that the designed observer is a cost effective solution since it requires only two measured state variables which are the voltages across the compensation capacitors. Finally, it was shown using simulation results that the estimated state variables match well the measured ones which verifies the accuracy of our observer.

I. Introduction

The need of a clean transportation system is becoming a necessity in our days in order to minimize the environmental impact of the traditional vehicles based internal combustion engines (ICE) [1]. With that being said, a lot of focus is made recently on Electric Vehicles (EVs) as a sustainable transportation system [2]. The transition toward this kind of vehicles can significantly reduce climate changes by reducing the quantity of warming gazes engaged in air such as Dioxide of Carbone. Despite its advantages towards the environment, it should be noted that there is a lot of factors limiting the success of EV making its adoption still in its earlier stages [3]. Among these factors one can note: i) the limited driving ranges due to the reduced storage capacity of the battery pack, ii) the lifetime of the battery pack, iii) the long charging time, and iv) the limited number of charging stations [4]. Talking about battery chargers, one must note that two solutions are developed: the conductive charger and the wireless charger [5]. The conductive charger may be the largely adopted solution in our days. It relies on standardized cables to transfer power from a power utility to the vehicle [6]. The main drawback of this solution could be the necessity of handling heavy cables and the risk of electric hazards when the charging operation is performed in presence of rain or snow [7]. The candidate solution which is the wireless charger is now in its earlier stages. The main advantage of this solution consists in the fact that the charging operation starts automatically without the need of any human intervention. With that being said, the charging operation using the wireless charger is safer, moreover, the comfort of the driver is guaranteed [8]. The wireless charging operation could be performed while the vehicle is parked, known as stationary wireless power transfer (solution already commercialized by many automakers such as BMW, Toyota,…) or while the vehicle is moving, known as dynamic charging (solution under researches) [9]. This paper focuses on the stationary wireless power transfer for EV. The following sections are addressed in this paper: •

Overview of a WPT system

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Modeling of a WPT system

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Observer design for a WPT system

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Simulation results