Education of Power Electronics in Japan

Matsui, Mikihiko,Ueda, Akiteru,Oguch, Kuniomi The Korean Institute of Power Electronics 2002 JOURNAL OF POWER ELECTRONICS Vol.2 No.4

Power electronics is an interdisciplinary area that is interstitial to all of the major disciplines of electrical engineering including power, electronics and control. Today, the covering field of power electronics has more widely spread out with the help of ever evolving microelectronics and computer science. Whereas, in Japan the tendency is becoming remarkable nowadays that science, especially "mathematics" and "hardware work", are falling into disfavor with the young people. For these reasons, it has become a very important problem to find out "what are the truest essentials of power electronics\ulcorner" and "How to give students incentives to learn power electronics\ulcorner " from an educational point of view In under-graduate and graduate courses in universities. On the other hand, the power electronics engineers in companies are always required to comply with the ever changing trend of global and open market. However, it takes long time to cultivate their skills. Against the background, "The Cooperative Research Committee on Education of Power Electronics" was established in the IEEJ Industry Applications Society during 2000-2001. The present status of the power electronics education in Japan is surveyed in this paper, and some problems with remedy are pointed out based on the discussions performed in the committee.sed on the discussions performed in the committee.

A Novel Interactive Power Electronics Seminar (iPES) Developed at the Swiss Federal Institute of Technology (ETH) Zurich

Drofenik, Uwe,Kolar, Johann W. The Korean Institute of Power Electronics 2002 JOURNAL OF POWER ELECTRONICS Vol.2 No.4

This paper introduces the Interactive Power Electronics Seminar - iPES - a new software package for teaching of fundamentals of power electronic circuits and systems. iPES is constituted by HTML text with Java applets for interactive animation, circuit design and simulation and visualization of electromagnetic fields and thermal issues in power electronics. It does comprise an easy-to-use self-explaining graphical user interface. The software does need just a standard web-browser, i.e. no installations are required. iPES can be accessed via the World Wide Web or from a CD-ROM in a stand-alone PC by students and professionals. Due to the underlying software technology iPES is very flexible and could be used for on-line learning and could easily be integrated into an e-learning platform. The aim of this paper Is to give an introduction to the iPES-project and to show the different areas covered. The e- learning software is available at no costs at $\underline{www.ipes.ethz.ch}$ in English, German, Japanese, Korean, Chinese and Spanish. The project is still under development and the web page is updated in about 4 weeks intervals.

Power Distribution Control Scheme for a Three-phase Interleaved DC/DC Converter in the Charging and Discharging Processes of a Battery Energy Storage System

Xie, Bing,Wang, Jianze,Jin, Yu,Ji, Yanchao,Ma, Chong The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

This study presents a power distribution control scheme for a three-phase interleaved parallel DC/DC converter in a battery energy storage system. To extend battery life and increase the power equalization rate, a control method based on the nth order of the state of charge (SoC) is proposed for the charging and discharging processes. In the discharging process, the battery sets with high SoC deliver more power, whereas those with low SoC deliver less power. Therefore, the SoC between each battery set gradually decreases. However, in the two-stage charging process, the battery sets with high SoC absorb less power, and thus, a power correction algorithm is proposed to prevent the power of each particular battery set from exceeding its rated power. In the simulation performed with MATLAB/Simulink, results show that the proposed scheme can rapidly and effectively control the power distribution of the battery sets in the charging and discharging processes.

Design and Implementation of Instantaneous Power Estimation Algorithm for Unified Power Conditioner

S., Sindhu,M.R., Sindhu,Nambiar, T.N.P. The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

This paper discusses a simple control approach for a Unified Power Conditioner (UPC) system to achieve power quality compensation at the point of common coupling in distribution systems. The proposed Instantaneous Power Estimation Algorithm (IPEA) for shunt and series active power filters uses a simple mathematical concept that reduces the complexity in the design of the controller. The performance of a UPC is verified with a system subjected to voltage distortions, sags/swells and unbalanced loads using MATLAB/SIMULINK. The simulation study shows that a UPC with the proposed control algorithm can effectively compensate for voltage and current harmonics, unbalance and reactive power. The control algorithm is experimentally implemented using dSPACE DS1104 and its effectiveness has been verified.

A Coordinative Control Strategy for Power Electronic Transformer Based Battery Energy Storage Systems

Sun, Yuwei,Liu, Jiaomin,Li, Yonggang,Fu, Chao,Wang, Yi The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

A power electronic transformer (PET) based on the cascaded H-bridge (CHB) and the isolated bidirectional DC/DC converter (IBDC) is capable of accommodating a large scale battery energy storage system (BESS) in the medium-voltage grid, and is referred to as a power electronic transformer based battery energy storage system (PET-BESS). This paper investigates the PET-BESS and proposes a coordinative control strategy for it. In the proposed method, the CHB controls the power flow and the battery state-of-charge (SOC) balancing, while the IBDC maintains the dc-link voltages with feedforward implementation of the power reference and the switch status of the CHB. State-feedback and linear quadratic Riccati (LQR) methods have been adopted in the CHB to control the grid current, active power and reactive power. A hybrid PWM modulating method is utilized to achieve SOC balancing, where battery SOC sorting is involved. The feedforward path of the power reference and the CHB switch status substantially reduces the dc-link voltage fluctuations under dynamic power variations. The effectiveness of the proposed control has been verified both by simulation and experimental results. The performance of the PET-BESS under bidirectional power flow has been improved, and the battery SOC values have been adjusted to converge.

Comparative Study on 220V AC Feed System and 300V DC Feed System for Internet Data Centers

Kim, Hyo-Sung The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

Internet Data Centers (IDCs), which are essential facilities in the modern IT industry, typically have scores of MW of concentrated electric loads. The provision of an Uninterruptible Power Supply (UPS) is necessary for the power feed system of IDCs owing to the need for stable power. Thus, conventional IDC AC power feed systems have three cascaded power conversion stages, (AC-DC), (DC-AC), and (AC-DC), resulting in a very low conversion efficiency. In comparison, DC power feed systems require only a single power conversion stage (AC-DC) to supply AC main power to DC server loads, resulting in comparatively high conversion efficiency and reliability [4-11]. This paper compares the efficiencies of a 220V AC power feed system with those of a 300V DC power feed system under equal load conditions, as established by the Mok-Dong IDC of Korea Telecom Co. Ltd. (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is approximately 15% higher than that of the 220V AC power feed system.

A New Control Scheme for Unified Power Quality Compensator-Q with Minimum Power Injection

Lee, Woo-Cheol The Korean Institute of Power Electronics 2007 JOURNAL OF POWER ELECTRONICS Vol.7 No.1

Voltage sags are one of the most frequently occurring power quality problems challenging power systems today. The Unified Power Quality Conditioner (UPQC) is one of the major custom power solutions that are capable of mitigating the effect of supply voltage sags at the load or Point of Common Coupling (PCC). A UPQC-Q employs a control method in which the series compensator injects a voltage that leads the supply current by $90^{\circ}C$ so that the series compensator at steady state consumes no active power. However, the UPQC-Q has the disadvantage that its series compensator needs to be overrated. Thus it cannot offer effective compensation. This paper proposes a new control scheme for the UPQC-Q that offers minimum power injection. The proposed minimum power injection method takes into consideration the limits on the rated voltage capacity of the series compensator and its control scheme. The validity of the proposed control scheme is investigated through simulation and experimental results.

Application of Fuzzy PI Control Algorithm as Stator Power Controller of a Double-Fed Induction Machine in Wind Power Generation Systems

Chung, Gyo-Bum,Choi, Jae-Ho The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.1

This paper addresses the output control of a utility-connected double-fed induction machine (DFIM) for wind power generation systems (WPGS). DFIM has a back-to-back converter to control outputs of DFIM driven by the wind turbine for WPGS. To supply commercially the power of WPGS to the grid without any problems related to power quality, the real and reactive powers (PQ) at the stator side of DFIM are strictly controlled at the required level, which in this paper is realized with the Fuzzy PI controller based on the field orientation control. For the Sinusoidal Pulse Width Modulation (SPWM) converter connected to the rotor side of DFIG to maintain the controllability of PQ at the state side of DFIM, the DC voltage of the DC link capacitor is also controlled at a certain level with the conventional Proportion-Integral (PI) controller of the real power. In addition, the power quality at the grid connected to the rotor side of DFIM through the back-to-back converter is maintained in a certain level with a PI controller of the reactive power. The controllers for the PQ at the stator side of DFIM, the DC link voltage of the back-to-back inverter and the reactive power at the grid connected to the rotor side of DFIM are designed and simulated in the PSIM program, of which the result verifies the performance of the proposed controllers.

A Study on Photovoltaic/Wind/Diesel Hybrid Power System

Jeong, Byung-Hwan,Cho, Jun-Seok,Gho, Jae-Seok,Choe, Gyu-Ha,Kim, Eung-Sang,Lee, Chang-Sung The Korean Institute of Power Electronics 2003 JOURNAL OF POWER ELECTRONICS Vol.3 No.1

In this paper, a hybrid power system with photovoltaic/wind/diesel generators is proposed to solve the defect of stand-alone type power system in a remote area. A hybrid power system has a power-balanced controller to equilibrate generation power with a given load demand and which is composed of common DC power system. To execute a power-balanced control, a hybrid power system is assumed that all of power generators have the characteristics of an equivalent current-source and load sharing control technique must be needed at the same time. So this paper discusses the structure of power-balance control for hybrid power system. And through the results of simulation, the proposed scheme was verified.

Evaluation and Design Tools for the Reliability of Wind Power Converter System

Ma, Ke,Zhou, Dao,Blaabjerg, Frede The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

As a key part in the wind turbine system, the power electronic converter is proven to have high failure rates. At the same time, the failure of the wind power converter is becoming more unacceptable because of the quick growth in capacity, remote locations to reach, and strong impact to the power grid. As a result, the correct assessment of reliable performance for power electronics is a crucial and emerging need; the assessment is essential for design improvement, as well as for the extension of converter lifetime and reduction of energy cost. Unfortunately, there still exists a lack of suitable physic-of-failure based evaluation tools for a reliability assessment in power electronics. In this paper, an advanced tool structure which can acquire various reliability metrics of wind power converter is proposed. The tool is based on failure mechanisms in critical components of the system and mission profiles in wind turbines. Potential methodologies, challenges, and technology trends involved in this tool structure are also discussed. Finally, a simplified version of the tool is demonstrated on a wind power converter based on Double Fed Induction Generator system. With the proposed tool structure, more detailed information of reliability performances in a wind power converter can be obtained before the converter can actually fail in the field and many potential research topics can also be initiated.