Yu-Chen Liu

High-Efficiency Wireless Power Transfer System for Electric Vehicle Applications

In this brief, a high-efficiency wireless power transfer (WPT) system for electric vehicle charging application is studied and implemented. Series–series resonant topology with RF feedback design is adopted as the WPT dc–dc stage due to the advantages of circuit simplicity, easy analysis, and control. A 500-W laboratory prototype is built and tested to verify the feasibility of the proposed design. According to the experimental results, high wall-to-battery efficiency and unity power factor can be achieved over an air gap of 15 cm and maximum sliding distance of 10 cm under various power conditions and universal input voltage from 90VAC to 264VAC.

Perspective on developing educational lecture videos for power electronics courses

Online learning resources are gaining wider attention, especially as flipped-learning and massive open online courses are becoming more popular. Various types of lecture videos were developed for an introductory power electronics course, implemented based on the flipped learning educational model. The approach and pedagogy is outlined for these flipped-learning courses and video lecture development. Feedback and responses from students is used to evaluate and discuss the effect of video quality on student learning and explore effective video qualities. Generally, self-made and professional videos both show similar learning effectiveness. Student feedback indicates that many students prefer the self-made videos over the professional videos, which takes significantly less prep time for the instructor. Students in the classes generally reacted positively to flipped learning using online lecture videos and expressed a demand for more educational video content on power electronics.

Opening the Box: Survey of High Power Density Inverter Techniques From the Little Box Challenge

The Little Box Challenge (LBC) was a competition sponsored by Google and the IEEE Power Electronics Society in 2014–2015, where participants were challenged to design a high power-density single-phase 2 kVA inverter. This paper surveys the designs from eight different participating teams, including academic grant awardees, finalists, and the winners. Inverter topologies, power decoupling circuits, and thermal management strategies are overviewed for each team. Wide bandgap switches were heavily utilized in both the inverter and power decoupling circuits, particularly GaN switches. Most teams utilized a full-bridge inverter with some variations and the most common power decoupling strategy was the use of a synchronous buck converter and a power buffering capacitor. One team used a multi-level inverter approach and a number of teams proposed innovative power decoupling topologies. Heat sinks and active cooling systems, many of which were custom made, were crucial for teams to stay within the 50 °C case temperature limit. The resulting power density of the surveyed teams ranged from 55.8 to 216 W/in 3 , all of which exceed the 50 W/in 3 LBC requirement. This paper surveys the approaches for various teams, shares experimental results from the Taiwan Tech team, and highlights some innovations from the teams that participated in the LBC.

Output double-line frequency ripple reduction method for high power density interleaved boost converters in power factor correction applications

A three-phase interleaved boost converter stage of an ac-dc PFC converter that uses GaN switches is developed that utilizes a feed-forward band-stop filter control method to suppress low-frequency output voltage ripple. To increase power density, the converter switches at 500 kHz, operates in triangular current mode (TCM) to achieve zero voltage switching (ZVS), and uses GaN switching devices. A 1-kW laboratory prototype was designed and tested to verify feasibility. With the proposed controller, output ripple was reduced by 70%. Overall efficiency is greater than 96.5% and power density is 65.028 W/in3.

High efficiency and low input current distortion Totem-Pole Bridgeless PFC

As time progresses and technology develops in recent years, the demand for networking communication products is on the increase. Almost all nations throughout the world adopt AC power transmission system. To avoid current phase shift or distortion that would indirectly influence energy conversion performance and power quality in the AC-DC conversion process, its important to insert PFC into power supplies. A PFC is to change the waveform of current drawn by a load to improve the power factor, reduce input current spike and control the harmonic current. This proposal aimed to design and implement a high efficiency, high power factor, high power density and low input current harmonic PFC. Due to the fast switching property of Wide Bandgap (WBG) Power Semiconductor Devices, it can reduce the loss and improve conversion efficiency, therefore increase the total power density.