Chapter One

Introduction 1

Chapter Two

2 Theoretical background 2

2.1 History of Wireless Power Transfer 2

2.2 Main concepts of wireless transmission of electric energy 3

2.3 Physics behind inductive coupling WPT 6

2.4 Health and safety considerations 11

2.5 Main WPT interface standards and alliances 12

2.5.1 Qi by the Wireless Power Consortium (WPC) 13

2.5.2 Rezence by the Alliance for Wireless Power (A4WP) 13

2.5.3 Power Matters Alliance (PMA) 13

2.6 Wireless power market overview 14

Chapter Three

Methods and materials 19

3.1 Texas Instruments Qi compliant modules evaluation 19

3.2 NextFloor custom 40W WPT system 23

3.3 PCB schematic design 24

3.3.1 Transmitter schematic 24

3.3.2 Receiver schematic 28

3.4 PCB layout design 34

Chapter Four

 Results and discussion 38

4.1 Tests and measurements 38

4.1.1 Efficiency evaluation 39

4.1.2 EMF test 42

4.1.3 EMC scan 42

4.2 Development of the NextFloor WPT prototypes 47

4.2.1 NextFloor + WPT concept 47

4.2.2 Qi-compatible demo-table 49

4.2.3 Non-standardized 40W WPT floor-demo 51

5 Conclusions 53

References 

Chapter One

1 Introduction

Wireless power transfer (WPT) is an important topic nowadays. Although WPT has been known for more than a century, only now has the WPT industry started its rapid growth. The number of publications on wireless power has increased by at least 1200%

in the last 10 years [9,2]. Current solutions are having great success in the marketplace with diffusions of innovations from innovators to early adopters as of now. However the main focus of the current solutions is a “wow” factor which in most cases neglects convenience [7,14]. Obviously, there is a need for a real-life application, for average users

who are not particularly familiar with the engineering world and do not follow state of the art technologies.

The goal of the project was to evaluate and study the wireless power transfer technologies and physics behind it. The design and implementation of the wireless energy transmission system prototype and its implementation in the NextFloor innovative floor

was the main plan. It was crucial for NextFloor to integrate advanced technologies into their floor system in order to make it really “smart” and innovative and wireless power transfer was one of them.

WPT is a very broad though relatively new technology – almost 80% of my references

are dated later than the year 2010; hence, the scope of the project was limited to implementation of the inductive power transfer mode only. However, other types of WPT are also discussed in the thesis. The question my project was aimed to answer was

simple: Are we ready to use cordless electricity in our everyday lives?

Last but not least, my utmost aims that I set in the beginning were to apply the gained knowledge in practice, assess my professional competence and development needs and learn how to work in a professional team researching a totally new technology.