International Future Energy Challenge 2018

International Future Energy Challenge 2018 – High Power Density High Efficiency Isolated Bidirectional DC-DC Converter for Residential Energy Storage Systems


Team Introduction

My name is John Brothers and I am the team lead for Ohio State University’s International Future Energy Challenge (IFEC) 2018 competition team.  Our team currently consists of four Ohio State University students – three undergraduates (John Brothers, Jeff Hensal, Matt Foster) and one graduate (Boxue He).  We have been actively researching IFEC 2018 since May 2017.


IFEC 2018 Introduction

IFEC started in 2001 and is now one of the world’s largest power electronics competitions, focusing on innovation, conservation, and effective use of electrical energy.  Hence, the IFEC 2018 competition topic is the high efficiency and high power density isolated bidirectional DC-DC converter for residential energy storage systems.

This battery charger is an essential component for integrating renewable energy sources at the residential level.  Because of renewable energy sources’ inherent intermittency, the ability to store and use this energy when needed is essential.  With continual research and development in the area of distributed energy generation systems (and the components that compose it such as our battery charger), the use of renewable energy sources will become more economically viable.  With time, this research area will directly affect the adoption of renewables at a global scale.  


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Current Status

Based on our team’s initial proposal, we were accepted through the first round of IFEC 2018 alongside 16 other university teams.  To get to the final competition for IFEC 2018, we will be presenting our progress including our first prototype’s preliminary results at APEC 2018 on March 4th.  Based on our presentation and a progress report we will write, a judging panel will determine what teams will advance to the final competition in July 2018 at Tsinghua University in Beijing, China.  


TECHNICAL DETAILS

Circuit Requirements

·        Low voltage side: Vbattery = 35V - 50V (DC), current ripple < 3% at full load

·        High voltage side: VHV = 400V (DC), voltage ripple < 2% at full load

·        Output power: 1kW

·        Power density: >1.5 W/cm3

·        Efficiency: >96% at 1kW, >94% at 500W, >92% at 250W


Circuit Overview

               Our circuit has 5 main boards.  The top layer includes three boards: 1) a Full Bridge (FB) DC/AC converter, 2) a planar transformer and planar inductor board, and 3) a Quasi Switched Capacitor (QSC) AC/DC converter.  These three boards compose the main power stage.  The middle layer is the aux power board, which generates all the isolated voltages needed to run all the gate drive circuits, the MCU, and digital ICs.  The bottom layer is the digital and MCU interface board which does all the fault reporting and handling, gate outputs, and interfaces the MCU. 


Full Bridge Main Power Stage PCB

               This board implements a full bridge DC/AC topology using 80V GaN MOSFETs.  This board also has the gate drive circuits for the four MOSFETs in the full bridge.  It takes the DC voltage from the battery and outputs an AC voltage to the isolation transformer.  


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Quasi Switched Capacitor Main Power Stage PCB

               This board implements the quasi switched capacitor DC/AC topology using 600V GaN MOSFETs.  This board has gate drives for its three MOSFETs.  It takes the 400V DC voltage and outputs an AC waveform to the isolation transformer.  


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Aux power stage PCB

            The aux power stage board interfaces our digital board and the main power stage.  This board takes the battery voltage and generates all the isolated voltages that power the entire circuit.  For the main power stage, this board provides the appropriate voltages for all the gate drive ICs and voltage/ current sensor ICs.  For the digital board, this board provides 5V and 3.3V for the logic ICs and MCUs.  


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Digital stage PCB

            The digital board interfaces the aux power stage and two MCUs and their respective development boards.  This board has several logic ICs which collaborate with the primary MCU for appropriate short circuit fault handling.  Attached are two MCU development boards.  One of them is our primary MCU, which is in charge of the closed loop control of our main power stage.  The second is a less powerful MCU with a compatible LCD screen attachment.  This will be used to monitor the status of the converter (voltage, current, and power displayed in real time) as well as select circuit operation mode and set maximum and minimum voltage, current, and power settings.  


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Words to PCBWay

Thank you for considering our competition team.  We are grateful for any PCB assistance provided by PCBWay.  We hope that you can help make our vision to get to the IFEC 2018 final competition a reality.  


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Feb 01,2018
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