Final defence: Megahertz Wireless Power Transfer System with High Controllability and Flexibility
Date: 2021/05/17 - 2021/05/17
Doctoral dissertation defence: Megahertz Wireless Power Transfer System with High Controllability and Flexibility
Speaker: Jibin Song, Ph.D candidate in University of Michigan – Shanghai Jiao Tong University Joint Institute
Time: 03:00 p.m.-05:00 p.m., May 17, 2021 (Beijing Time)
Location: Room 454, JI Building
Abstract
Wireless power transfer (WPT) serves as a promising solution to charge everyday equipment, from cell-phones to electric vehicles. This technology has attracted great interests from academia and industry in recent years. Increasing the frequency to MHz can help achieve lighter and more compact WPT systems with higher spatial freedom. Moreover, with loosely coupled coils, MHz WPT makes it possible to charge multiple receivers simultaneously.
For MHz WPT in mobile applications, the receiver is usually embedded inside the devices, which makes the heating issue quite challenging. To improve the efficiency of receiver, a universal optimal drain-source-voltage (ODSV) tracking scheme for synchronous resonant rectifier is proposed. The ODSV tracking enables the switches in the synchronous rectifiers work at the same switching operation with that of the diodes in the passive rectifiers. Therefore, minimized switching/conduction loss and maximized efficiency can be achieved. Moreover, for resonant rectifiers, the duty cycle can be tuned to control the output voltage. As an example, a Class E active rectifier with controllable output voltage is analyzed and its system-level application in WPT is well presented. Besides rectifiers, a stacked receiving coil and its compensation method are also proposed to improve the efficiencies. The stacked coil is fabricated with multi-layer printed circuit board (PCB) with foil coils stacked with each other. The proposed compensation methodology can maintain optimal operation with variable coupling and loading conditions. For multiple-receiver WPT, challenges lie in differences in load characteristics, power level, and cross coupling effects. Accordingly, this dissertation proposes a scalable solution for multiple-receiver WPT, which can simultaneously achieve high efficiency and desired individual load powers over variable cross couplings and number of receivers.
Biography
Jibin Song is a PhD student at the University of Michigan-Shanghai Jiao Tong University Joint Institute. He received the bachelor degree from Jilin University, Changchun, China, in 2016. His research interests include circuit-level and system-level designs of megahertz wireless power transfer systems, and circuit topologies, and control strategies of high-frequency power electronics.