Active Gate Drivers for High-Frequency Application of SiC MOSFETs-BY Alejandro Paredes Camacho-Thesis submitted in partial fulfilment of the requirement for the PhD degree issued by the Universitat Politècnica de Catalunya, in its Electronic Engineering Program.

Active Gate Drivers for High-Frequency Application of SiC MOSFETs-BY Alejandro Paredes Camacho-Thesis submitted in partial fulfilment of the requirement for the PhD degree issued by the Universitat Politècnica de Catalunya, in its Electronic Engineering Program. 

 Abstract 

The trend in the development of power converters is focused on efficient systems with high power density, reliability and low cost. The challenges to cover the new power converters requirements are mainly concentered on the use of new switching-device technologies such as silicon carbide MOSFETs (SiC). SiC MOSFETs have better characteristics than their silicon counterparts; they have low conduction resistance, can work at higher switching speeds and can operate at higher temperature and voltage levels. Despite the advantages of SiC transistors, operating at high switching frequencies, with these devices, reveal new challenges. The fast switching speeds of SiC MOSFETs can cause over-voltages and over-currents that lead to electromagnetic interference (EMI) problems. For this reason, gate drivers (GD) development is a fundamental stage in SiC MOSFETs circuitry design. The reduction of the problems at high switching frequencies, thus increasing their performance, will allow to take advantage of these devices and achieve more efficient and high power density systems. This Thesis consists of a study, design and development of active gate drivers (AGDs) aimed to improve the switching performance of SiC MOSFETs applied to high-frequency power converters. Every developed stage regarding the GDs is validated through tests and experimental studies. In addition, the developed GDs are applied to converters for wireless charging systems of electric vehicle batteries. The results show the effectiveness of the proposed GDs and their viability in power converters based on SiC MOSFET devices.

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13.56 MHz high power and high efficiency inverter for dynamic EV charging systems A DISSERTATION SUBMITTED TO THE GRADUATE SCHOOL OF ENGINEERING AND SCIENCE OF SHIBAURA INSTITUTE OF TECHNOLOGY by NGUYEN KIEN TRUNG IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY SEPTEMBER 2016

 

13.56 MHz high power and high efficiency inverter for dynamic EV charging systems

A DISSERTATION SUBMITTED TO THE GRADUATE SCHOOL OF ENGINEERING AND SCIENCE OF SHIBAURA INSTITUTE OF TECHNOLOGY by NGUYEN KIEN TRUNG IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY SEPTEMBER 2016

 Abstract 

Recently, Electric Vehicles (EVs) are a promising solution for reduc- ing CO2 emission and air pollution in the big cities. However, until now, the EVs have been not so attractive to consumers due to the short running distance, long charging time and high battery cost. The dynamic charging solution has been proposed to reduce the energy de- pendence and battery cost of EVs. As the demand of that systems, a 13.56 MHz high power inverter with the eciency of over 95% is re- quired. With the previous researches, there are three major research challenges have been recorded. At very high switching frequency such as 13.56 MHz, the in uence of the parasitic elements in the circuit is the rst challenge because it strongly aect both of power and drive circuit of the inverter. Consequently, the inverter may be damaged or unstable. Secondly, the switching and gate drive power loss in the inverter are also the challenge when it proportionally increase with the switching frequency. At 13.56 MHz, it is dicult to obtain the extremely high eciency such as 95%. Finally, the high output power required is another challenge due to the low rate-parameters and the challenges in the parallel connecting of the high speed switching de- vices. To overcome these challenges, a number of the analyses and proposed design are presented in this dissertation. Firstly, the eect of the parasitic elements in the high switch- ing frequency half-bridge inverter is analyzed and evaluated in detail based on the perspective of the ringing loop in the circuit. Based on these, an optimized PCB design is proposed to minimize the parasitic inductance in the ringing loop of the inverter. With the improved PCB, the experiment results show that, the peak voltage and the am- plitude of the ringing current in the circuit is reduced. However, the ZVS condition and the stability of the inverter at high input voltage condition are not achieved due to the high frequency ringing in the circuit. Therefore, a ringing damping circuit is proposed. The high stability and the low power loss on the proposed damping circuit is the advantage to obtain high eciency of the inverter. In the ex- periment results, the ringing current in the circuit is damped. A 1.2 kW output power is obtained with the eciency of 93.1%. This is an improvement in the 13.56 MHz inverter. However, it does not meet the required eciency of the inverter for the dynamic EV charging systems due to limited switching speed of the silicon-MOSFET. Secondly, to improve the eciency of the inverter, the GaN HEMT device is used. In an experiment, the inverter using GaN HEMT obtains the eciency of 97.5% which shows the potential to meet the required eciency of the inverter for the dynamic EV charging systems. However, the output power of the inverter is limited due to the low rate current of the GaN HEMT. And the parallel connection of GaN HEMT devices at 13.56 MHz is very dicult because of the strong unbalance dynamic current distribution. Therefore, a design using multiphase resonant inverter is proposed. The proposed module design, the proposed power loss analysis method to obtain highest eciency and the proposed drive circuit design have been addressed in detail. In experiment, a 3 kW inverter with the eciency of 96.1% is achieved that signicantly improves the eciency of 13.56 MHz inverter. A 10 kW inverter with the eciency of over 95% will be developed by following this proposed design in near future. Finally, the 13.56 MHz high power inverter with the eciency of over 95% can be realizable. However, the Class DE operation mode which is used in multiphase resonant inverter requires exact parameter of load, resonant circuit and several turning in the experiment process. Therefore, it is still dicult to apply in the dynamic charging systems where the parameters of the coupling system will always change in the operation. The inverter behavior analysis and the further researches to keep the soft switching condition in the operation with the dynamic coupling system are necessary in the future work.

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ISLANDING DETECTION AND POWER QUALITY ANALYSIS IN MICROGRID a Dissertation Submitted to the GRADUATE SCHOOL OF ENGINEERING AND SCIENCE OF SHIBAURA INSTITUTE OF TECHNOLOGY by TRAN THANH SON

 ISLANDING DETECTION AND POWER QUALITY ANALYSIS IN MICROGRID 

a Dissertation Submitted to the GRADUATE SCHOOL OF ENGINEERING AND SCIENCE OF SHIBAURA INSTITUTE OF TECHNOLOGY 

by TRAN THANH SON 

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY SEPTEMBER 2019

Abstract

The microgrid (MG) has been developed based on the important con- cept of distributed generation (DG) with high penetration of renew- able energy integrated with energy storage systems (ESSs). MGs can operate in both grid-connected and islanding mode. Therefore, this thesis focuses on autonomous multi-islanded entities and the seamless reconnection to the main grid as the self-healing ability of the fu- ture power system. The minimization of power quality issues (mainly that of voltage, frequency, and harmonics) in such entities based on controllers, with or without intercommunication, is also an important part of this thesis. The future power system, with the signicant pen- etration of distributed generations (DGs), can rapidly respond to any problem occurring within it by separating into autonomous islanded entities to prevent the disconnection of DGs. As a result, high-quality and continuous power is supplied to consumers. The future research that is necessary for the realization of the future power system is discussed.

Besides, the emergence of Distributed Generation (DG) in the elec- tric system has brought about the appearance of the islanding phe- nomenon. In AC networks, there are a lot of Islanding Detection Methods (IDMs) have been studied. However, not too much IDMs in DC networks have been published because of the absence of frequency and reactive power. The active IDM based on injected perturbation signal and rate of change of power output is proposed. This IDM can detect islanding condition not only in the worst case (the power of the load and PV are equal) but also in another case (the power of load is greater than the power of PV). It can be applied to both single

and multi-PV operation scenarios. Also, the cancellation problem is analyzed and the solution is proposed to solve this problem. Besides, the eectiveness of the proposed method, the cancellation problem, and the solution are verified by simulation in Matlab/Simulink.

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Development of High-Step-Up IsolatedDCDC Converter based on Super-High Frequency Switching to Physical Limit in Circuit Devices-Department of Electrical Engineering, Kobe City College of Technology Masataka Minami

Development of High-Step-Up IsolatedDCDC Converter based on Super-High Frequency Switching to Physical Limit in Circuit Devices-Department of Electrical Engineering, Kobe City College of Technology Masataka Minami

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Shibaura Institute of Technology doctoral degree thesis High frequency inverter for plasma generation equipment, and research on high frequency matching devices.-芝 浦 工 業 大 学 博 士 学 位 論 文 プラズマ生成装置の高周波インバータ、 および高周波整合器に関する研究 平成 29 年3 月

 

Shibaura Institute of Technology doctoral degree thesis High frequency inverter for plasma generation equipment, and research on high frequency matching devices. March 2017 

 芝 浦 工 業 大 学 博 士 学 位 論 文 プラズマ生成装置の高周波インバータ、 および高周波整合器に関する研究 平成 29 年3 月

Overview 

This paper is concerned with high-frequency plasma generation equipment for functional devices, semiconductor and liquid crystal manufacturing equipment, and aims to reduce power loss in high-frequency inverters, improve power conversion efficiency, and wide-range impedance matching of high-frequency matching boxes using high-frequency transformers. This is a summary of research results regarding. Thin film formation using high-frequency plasma, such as plasma chemical vapor deposition (Plasma CVD), is widely used in the production of semiconductors, liquid crystals, and solar cells. In recent years, the range of applications has expanded to include thin film coatings for industrial purposes. Furthermore, as a pretreatment for a physical vapor deposition (PVD) process, high-frequency plasma treatment using high-frequency waves is widely used to remove a natural oxide film (pre-clean). Conventionally, the mainstream of photoresist stripping treatments has been treatments that do not involve physical reactions, such as liquid etching treatment (wet etching) using acidic or alkaline solutions. In recent years, dry etching, which uses high-frequency plasma to etch materials with reactive gases, etching gases, ions, and radicals, has become mainstream in semiconductors, liquid crystals, and manufacturing equipment. High-frequency plasma technology is becoming increasingly important in the research and development of functional devices. Conventionally, high-frequency inverters with a frequency of 13.56 MHz and a high-frequency output of 1 kW, which are often used in semiconductor manufacturing equipment, have a low high-frequency power conversion efficiency of about 50%, and about 1 kW of power loss is converted into heat. To dissipate 1 kW of heat, a water-cooled heat exchanger and auxiliary equipment were required, which required 200 liters of cooling water per hour. There were also problems from the environmental standpoint of cooling water and ancillary equipment, energy consumption, and economics. In this study, we focused on high-frequency output transformers with the aim of reducing high-frequency power loss and improving power conversion efficiency. Conventionally, a high-frequency output of 1 kW was obtained using four output transformers, but in this research, we investigated a high-efficiency, high-frequency output transformer, and a circuit configuration that achieves a high-frequency output of 1 kW. By using a single high-frequency inverter with a high-frequency output of 1 kW, it is possible to The high frequency output synthesizer used in the frequency inverter is no longer required. Therefore, we investigated ways to reduce power loss in high-frequency output combiners. To create a single high-frequency output transformer, four MOS-FETs must be connected in parallel. We investigated a push-pull type high-frequency inverter with four MOS-FETs connected in parallel using an axial printed circuit board (PCB). We also investigated power loss and temperature at high frequencies in high-frequency output transformers and high-frequency output combiners, which are important in realizing high-efficiency, high-frequency inverters. Furthermore, we evaluated and investigated the power loss and temperature at high frequencies of the high frequency ferrite core that constitutes the high frequency output transformer. Conventionally, in an ICP dry etching system using an L-type high-frequency matching box used in inductively coupled plasma (ICP), the chamber pressure used for high-frequency plasma generation is a low pressure of about 0.1 to 13 Pa, and a pressure of 1011 cm-3 or more is used for generating high-frequency plasma. High density plasma can be obtained. ICP high-frequency plasma is currently the mainstream etching method in semiconductor etching processes because high-density plasma can be obtained without using an electromagnetic coil. In the production of functional devices, photocurable resin (photoresist) is used.

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