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About this book

This book describes the fundamentals and applications of wireless power transfer (WPT) in electric vehicles (EVs). Wireless power transfer (WPT) is a technology that allows devices to be powered without having to be connected to the electrical grid by a cable. Electric vehicles can greatly benefit from WPT, as it does away with the need for users to manually recharge the vehicles’ batteries, leading to safer charging operations. Some wireless chargers are available already, and research is underway to develop even more efficient and practical chargers for EVs. This book brings readers up to date on the state-of-the-art worldwide. In particular, it provides: • The fundamental principles of WPT for the wireless charging of electric vehicles (car, bicycles and drones), including compensation topologies, bi-directionality and coil topologies. • Information on international standards for EV wireless charging. • Design procedures for EV wireless chargers, including software files to help readers test their own designs. • Guidelines on the components and materials for EV wireless chargers. • Review and analysis of the main control algorithms applied to EV wireless chargers. • Review and analysis of commercial EV wireless charger products coming to the market and the main research projects on this topic being carried out worldwide. The book provides essential practical guidance on how to design wireless chargers for electric vehicles, and supplies MATLAB files that demonstrate the complexities of WPT technology, and which can help readers design their own chargers.

Table of Contents

Frontmatter

Chapter 1. Fundamentals of Wireless Power Transfer

Abstract
Wireless power transfer comprises a set of heterogeneous technologies. Their correct applicability depends on the power requirements and the scenario in which it is expected to be used (position between transmitter and receiver, separation between them, electronics dimensions, etc.). First, this chapter describes how wireless power transfer systems have evolved. Then, the main operating principles of the wireless power techniques are explained.
Alicia Triviño-Cabrera, José M. González-González, José A. Aguado

Chapter 2. Wireless Chargers for Electric Vehicles

Abstract
Electric vehicles constitute an important asset in the sustainable transportation sector. Wireless technology allows for a user-friendly charge/discharge process in EVs. This technology may also prompt an autonomous operation as users’ intervention is avoided. In order to promote the use of WPT in EVs, the wireless chargers should be designed so as to meet the requirements established by conductive chargers. This chapter describes the main aspects to consider in relation to conductive charge in EVs. Based on this, the general structure of a wireless charger for EVs is presented.
Alicia Triviño-Cabrera, José M. González-González, José A. Aguado

Chapter 3. Coil Design for Magnetic Resonance Chargers

Abstract
The pair of coupled coils constitutes the core of magnetic resonance chargers. Several geometries are possible for these elements. The geometry of the coils must be judiciously selected in the design process in order to meet requirements regarding sensitivity to misalignment, efficiency and leakage magnetic flux. This chapter reviews the usual geometries for coils in EV wireless chargers, including static and dynamic applications. It also describes the method to effectuate an adequate shielding.
Alicia Triviño-Cabrera, José M. González-González, José A. Aguado

Chapter 4. Compensation Networks

Abstract
Compensation networks are additional structures composed of capacitors and even coils in some cases. These elements are incorporated into the magnetic resonance chargers to configure a resonant tank with the coils that generate the magnetic field. In this way, the power transfer of the wireless charger can be significantly improved. There are multiple configurations in which the reactive elements of the compensation networks are arranged. When designing a magnetic resonance charger, it is important to carefully decide which compensation topology is being applied. For this decision, three main features should be considered. Firstly, the compensation topology will influence the system’s capacity to cope with misalignment. Secondly, some topologies allow for passive control, i.e. they can work as a constant current or voltage source independently of the load features. Thirdly, the compensation topologies define the stability of the system when considering the bifurcation phenomenon. This chapter discusses the main compensation topologies applied to EV wireless chargers, providing an in-depth analysis of their impact on the whole system. This study includes mono-resonant and multi-resonant topologies.
Alicia Triviño-Cabrera, José M. González-González, José A. Aguado

Chapter 5. Power Electronics

Abstract
Magnetic resonance power transfer is achieved by means of an electromagnetic field. Specifically, the induced voltage is related to the rate of variation in the magnetic flux. Taking into account the voltages required in EV charging and the maximum space available to allocate the coils in the vehicle, it is concluded that the frequency of the electrical signal provided by the grid is not sufficient for this operation. Consequently, frequency conversion becomes a necessary step in EV wireless chargers. For this operation, power converters are incorporated on both the primary and the secondary sides. This chapter reviews the topologies of the power converters used in EV wireless chargers, paying special attention to the control techniques. This review comprises uni-directional and bi-directional wireless chargers.
Alicia Triviño-Cabrera, José M. González-González, José A. Aguado

Chapter 6. Design Procedure of an EV Magnetic Resonance Charger

Abstract
The appropriate design of a WPT charger encompasses multiple decisions, which include the coil geometry and the configuration of the power converters. This chapter proposes 8 phases to follow when approaching this kind of design. After an in-depth analysis of the application requirements and their impacts on the design, an iterative algorithm should be executed to determine the coil geometries and the topologies of the compensation networks. This chapter includes a description of the proposed approach. Through an illustrative example, we show how the design procedure can be applied.
Alicia Triviño-Cabrera, José M. González-González, José A. Aguado

Backmatter

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