Rm. 303a / 14:00-17:00, Sunday, June 4
Wireless Power Transfer for Electric Vehicle and Mobile Applications

Prof. Chris Mi

Fellow IEEE
San Diego State University
Chris Mi is a fellow of IEEE, Professor and Chair of the Department of Electrical and Computer Engineering, and the Director of the US DOE funded GATE Center for Electric Drive Transportation at San Diego State University, San Diego, California, USA. He was previously a professor at the University of Michigan, Dearborn from 2001 to 2015. Previously he was an Electrical Engineer with General Electric Canada Inc. He was the President and the Chief Technical Officer of 1Power Solutions, Inc. from 2008 to 2011. He is the Co-Founder of Gannon Motors and Controls LLC and Mia Motors, Inc.

His research interests are in electric and hybrid vehicles. He has taught tutorials and seminars on the subject of HEVs/PHEVs for the Society of Automotive Engineers (SAE), the IEEE, workshops sponsored by the National Science Foundation (NSF), and the National Society of Professional Engineers. He has delivered courses to major automotive OEMs and suppliers, including GM, Ford, Chrysler, Honda, Hyundai, Tyco Electronics, A&D Technology, Johnson Controls, Quantum Technology, Delphi, and the European Ph.D School. He has offered tutorials in many countries, including the U.S., China, Korea, Singapore, Italy, France, and Mexico. He has published more than 100 articles and delivered 30 invited talks and keynote speeches. He has also served as a panelist in major IEEE and SAE conferences.

Dr. Mi is the recipient of “Distinguished Teaching Award” and “Distinguished Research Award” of University of Michigan Dearborn. He is a recipient of the 2007 IEEE Region 4 “Outstanding Engineer Award,” “IEEE Southeastern Michigan Section Outstanding Professional Award.” and the “SAE Environmental Excellence in Transportation (E2T) Award.” He was also a recipient of the National Innovation Award and the Government Special Allowance Award from the China Central Government. In December 2007, he became a Member of Eta Kappa Nu, which is the Electrical and Computer Engineering Honor Society, for being “a leader in education and an example of good moral character.”
Electric vehicles and plug-in hybrid electric vehicles (PEVs) have attracted worldwide attentions because their capabilities to displace petroleum usage and improve energy and environment sustainability. One of the key constraints for the mass market penetration of PEVs is the inconvenience and safety concerns associated with charging. Wireless charging using wireless power transfer (WPT) technology, as an alternative to conductive charging or battery-swapping, can provide the convenience and safety requirements. Recently, EV battery wireless chargers have been realized at large power levels (>100kW) with reasonable sizes, distance in excess of 200 mm, DC-to-battery efficiency of 96.5%, and a misalignment of up to 600 mm, using inductive power transfer technology. This breakthrough will have strong impact on PEVs and a variety of other applications, including consumer electronics, home appliances, medical implant devices, and some industry applications.

This tutorial focuses on the principle and key technical challenges of WPT. It will contain five modules.
In module 1, we will provide an overview of wireless power transfer technology and its application in electric vehicle charging. Different terminologies in wireless power transfer will be explained. Various methods for wireless power transfer will be discussed. Magnetic resonance and compensation methods will be introduced.

In module 2, we will discuss the principle, theory, analysis methods, and applications of inductive wireless power transfer technology. Various types of coil design for maximum coupling coefficient, including circular, rectangular, flux pipe, double D, and DDQ coils. Measurements of coil inductance will be discussed. It will be aimed at novel designs that considerably reduce size and cost while increase coupling coefficient and system efficiency. A double sided LCC resonant converter topology for the resonant will be discussed in detail.

In module 3, the presentation discusses capacitive power transfer (CPT) for EV charging applications. It has been an established myth that good efficiency and stability of control was only possible in capacitive power transfer (CPT) at low power levels (in the tens of watts) and with low transfer distances (in the millimeter range). Dr. Chris Mi and his team have shown that it is possible to achieve excellent efficiencies at the power level and distance applicable to EV charging, breaking the established myth, enabling a paradigm change on EV charging, and making low cost wireless power transfer from science fiction to reality. A double-sided LCLCcompensated topology and its design process will be discussed in detail. The design of a 2.4kW CPT system with four 610mm × 610mm copper plates and an air gap distance of 150mm will be shown with a 90.8% efficiency.

Module 4 briefly discuss the power electronics circuits for WPT systems, such as AC-DC, DC-DC, and DCAC.

The last module will discuss other aspects of wireless chargers, such as safety issues, switching frequency band requirement, SAE WPT J2954 standard, object detection methods, communication methods between transmitter and receiver, some testing results of foreign object inserted between the transmitter and receiver exist.