Faculty Profiles - HIRAKI Eiji

Papers - HIRAKI Eiji

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Newly-Proposed Hybrid Resonant Commutaion Bridge Leg Link Snubber-Assisted Three-Phase ZVZCS-PWM Soft-Switching Inverter

HIRAKI Eiji, YOSHIDA Masanobu, HIROTA Yoshihiko, NAKAOKA Mutsuo

IEEJ Transactions on Industry Applications 124 ( 3 ) 286 - 294 2004.3

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

This paper presents the newly-proposed hybrid resonant commutation bridge leg link (HRCB) snubber circuit which can achieve zero voltage and zero current soft-switching commutation for single-phase and three-phase voltage source-type inverter, along with its unique features and operation principle. The circuit parameter design approach for the HRCB snubber circuit and the determination estimating scheme of the gate pulse timing processing which is more suitable and acceptable for single-phase and space voltage vector modulated three-phase voltage source inverter using the HRCB snubber circuit are described in this paper. In particular the three-phase voltage source soft-switching inverter associated with the proposed HRCB circuits are evaluated and discussed from simulation and experimental viewpoint. The practical effectiveness of the HRCB snubber-assisted three-phase voltage source soft-switching inverter using IGBT power modules which is based on the instantaneous space voltage vector modulation is clarified on the output voltage waveform, actual efficiency and electromagnetic noises in comparison with three-phase voltage source-type conventional hard-switching inverter.

DOI： 10.1541/ieejias.124.286

Static VAR compensator-based terminal voltage regulation scheme of self-excited induction generator driven by variable speed prime mover for clean renewable energy utilizations

Tarek Ahmed, Eiji Hiraki, Mutsuo Nakaoka, Osamu Noro

Conference Proceedings - IPEMC 2004: 4th International Power Electronics and Motion Control Conference 3 1219 - 1224 2004

A novel soft switching PWM sinewave converter with regenerative pulse current edge-resonant snubber power modules for distributed power supplies

Mantaru Nakamura, Tarek Ahmed, Eiji Hiraki, Mutsuo Nakaoka

IEE Conference Publication 1 203 - 208 2004

New Space Vector Modulated 3-Level 3-Phase Voltage-Source Soft-Switching Inverter with Two Active Resonant DC Link Snubbers

YAMAMOTO Masayoshi, SATO Shinji, HIRAKI Eiji, NAKAOKA Mutsuo

IEEJ Transactions on Industry Applications 123 ( 12 ) 1397 - 1405 2003.12

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

This paper presents a novel prototype of 3-level 3-phase voltage-fed soft switching commutation inverter with two Active Auxiliary Resonant DC Link (ARDCL) snubbers which can operate under a condition of Zero Voltage Switching (ZVS) transition. Its operating principle is described herein. The feasible steady-state performances of the proposed soft switching commutated inverter using the latest IGBTs such as planner type and trench type IGBTs, which is more suitable for power systems applications, are evaluated and discussed on the basis of its experimental results and simulation ones.

DOI： 10.1541/ieejias.123.1397

High-Efficient High Frequency Linked Zero Voltage Soft Switching PWM DC/DC Power Converter with ON/OFF-Assisted Synchronous Rectifier Scheme

SATO Shinji, MOISSEEV Serguei, ISHITOBI Manabu, HIRAKI Eiji, NAKAOKA Mutsuo

IEEJ Transactions on Industry Applications 123 ( 12 ) 1414 - 1421 2003.12

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

Advanced development of the high frequency pulse modulated DC/DC power converters are indispensable in order to achieve smaller size, higher performances of the power supplies. In resent years the problems of the electromagnetic noise generation caused by the hard-switching pulse width modulation (PWM)—based high frequency operation of the switching power devices have been significant, including switching losses and switching surges. As result a variety of soft-switching power conversion circuit technologies have been attracted special interests for reducing switching power losses and minimizing electromagnetic interference. The soft-switching pulse modulation of DC/DC power circuit topologies can be divided into continuous current mode resonant type and quasi-resonant voltage mode type. The soft-switching DC/DC converters, a continuous current mode zero current soft-switching (ZCS) DC/DC converter with pulse frequency modulation (PFM) has been already put into a practical use. In this sort of power converters soft-switching commutation can be achieved over wide load variation ranges and high stability can be also performed, but high current peak stress through power semiconductor devices arises, however, and it causes relatively large increase of conduction power losses in the power semiconductor devices, high frequency transformers as well as rectifier diodes. As a result, the problem of a high efficiency for DC/DC power converter could not still unsolved.<br>Thereupon, in this paper, quasi-resonant voltage mode based soft-switching PWM DC/DC power converter with a high frequency transformer link is presented, which has on/off assisted synchronous rectifier in its secondary side. The PWM operation of this converter is described in comparison with conventional one. Due to using power MOSFET as on/off assisted synchronous rectifier in the secondary side of the high frequency isolated transformer, it is possible to achieve stable zero voltage soft-switching (ZVS) conditions from no load to the rated load for minimum requirement of a magnetizing current. As result of a high value of the magnetizing inductance design, the power converter actual efficiency of this converter can be designed so as to above 97% in experiment. Moreover, results of a switching losses analysis are discussed from an experimental point of views in this paper. The effectiveness of the power converter treated hare is proved from a practical point of view by using 32kHz-2.5kW breadboard setup.

DOI： 10.1541/ieejias.123.1414

Consideration of Time Sharing Output Pulse Pattern Using Instantaneous Space Voltage Vector Moderation for Three-Phase Voltage Source Soft-Switching Inverter

YOSHIDA Masanobu, HIRAKI Eiji, NAKAOKA Mutsuo

The Transactions of the Institute of Electronics, Information and Communication Engineers B 86 ( 11 ) 2417 - 2422 2003.11

Performance Evaluations of A Single Inductor Type Resonant AC Link Snubber-Assisted Three-Phase Voltage Source Soft-Switching Inverter

YOSHIDA Masanobu, HIRAKI Eiji, NAKAOKA Mutsuo

IEEJ Transactions on Industry Applications 123 ( 11 ) 1269 - 1275 2003.11

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

This paper presents a novel three-phase voltage source type soft-switching inverter using the main and auxiliary IGBT power module packages in order to reduce their switching power losses as well as its electromagnetic noises. A single inductor-assisted resonant AC link snubber circuit as one of some resonant snubbers to achieve the zero voltage soft-switching for the three-phase voltage source inverter (VSI) with instantaneous space voltage vector sinewave modulation strategy is originally demonstrated as compared with the other resonant AC link snubber circuit topologies. In addition to this, its operation principle and unique features are described in this paper for resistive and inductive loads. Furthermore, the practical basic operating performances of the new instananeous space vector modulated soft-switching VSI using IGBT power modules are evaluated and discussed on the basis of power conversion efficiency and electromagnetic conductive and radiative noises from an experimental point of view, as compared with those of hard-switching VSI.

DOI： 10.1541/ieejias.123.1269

Design Method of Digital Optimal Control Scheme and Multiple Paralleled Bridge Type Current Amplifier for Generating Gradient Magnetic Fields in MRI Systems

WATANABE Shuji, TAKANO Hiroshi, FUKUDA Hiroya, HIRAKI Eiji, NAKAOKA Mutsuo

IEEJ Transactions on Industry Applications 123 ( 8 ) 894 - 902 2003.8

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

This paper deals with a digital control scheme of multiple paralleled high frequency switching current amplifier with four-quadrant chopper for generating gradient magnetic fields in MRI (Magnetic Resonance Imaging) systems. In order to track high precise current pattern in Gradient Coils (GC), the proposal current amplifier cancels the switching current ripples in GC with each other and designed optimum switching gate pulse patterns without influences of the large filter current ripple amplitude. The optimal control implementation and the linear control theory in GC current amplifiers have affinity to each other with excellent characteristics. The digital control system can be realized easily through the digital control implementation, DSPs or microprocessors. Multiple-parallel operational microprocessors realize two or higher paralleled GC current pattern tracking amplifier with optimal control design and excellent results are given for improving the image quality of MRI systems.

DOI： 10.1541/ieejias.123.894

Effective Improvement of DC Busline Voltage Utilization Factor in Two Switch-Auxiliary Quasi-Resonant DC Link Snubber Assisted Three Phase Voltage Source Type Soft-Switching PWM Inverter

NAGAI Shinichiro, SATO Shinji, YAMAMOTO Masayoshi, HIRAKI Eiji, NAKAOKA Mutsuo

IEEJ Transactions on Industry Applications 123 ( 6 ) 710 - 716 2003.6

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

In recent years, a resonant snubber to minimize switching power losses and EMI noises have attracted special interest for the voltage-fed soft switching sinewave PWM inverters and active rectifiers. The authors have discussed the performance evaluations on lower noise and high efficiency for two switch auxiliary resonant DC link snubber assisted three-phase voltage-fed soft switching PWM inverter. It was proved that cost effective three phase soft switching inverter treated here is able to improve both efficiency and EMI noise. However, some practical problems to be improved have recognized for the soft-switching three phase PWM inverter treated here from a practical point of view. This three phase soft-switching inverter with two switch type auxiliary resonant DC link snubber has significant disadvantages of DC busline link voltage reduction for the existence of the zero voltage mode transition period as well as the larger size and physical volume of electrolytic capacitor incorporated into the resonant DC link snubber. The additional technology to minimize the busline DC link zero voltage period in order to overcome the practical problems mentioned above is newly proposed in this paper. From experimental and simulation viewpoints, the modified version of this soft-switching inverter is discussed and evaluated for the DC busline voltage utilization factor as compared with the previously developed one.

DOI： 10.1541/ieejias.123.710

Improved Transient and Steady-State Perfomances of Series Resonant ZCS High-Frequency Inverter-Coupled Voltage Multiplier Converter with Dual Mode PFM Control Scheme

CHU Enhui, GAMAGE Laknath, ISHITOBI Manabu, HIRAKI Eiji, NAKAOKA Mutsuo

IEEJ Transactions on Industry Applications 123 ( 6 ) 649 - 659 2003.6

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

The A variety of switched-mode high voltage DC power supplies using voltage-fed type or current-fed type high-frequency transformer resonant inverters using MOS gate bipolar power transistors; IGBTs have been recently developed so far for a medical-use X-ray high power generator. In general, the high voltage high power X-ray generator using voltage-fed high frequency inverter with a high voltage transformer link has to meet some performances such as (i) short rising period in start transient of X-ray tube voltage (ii) no overshoot transient response in tube voltage, (iii) minimized voltage ripple in periodic steady-state under extremely wide load variations and filament heater current fluctuation conditions of the X-ray tube. <BR>This paper presents two lossless inductor snubber-assisted series resonant zero current soft switching high-frequency inverter using a diode-capacitor ladder type voltage multiplier called Cockcroft-Walton circuit, which is effectively implemented for a high DC voltage X-ray power generator. This DC high voltage generator which incorporates pulse frequency modulated series resonant inverter using IGBT power module packages is based on the operation principle of zero current soft switching commutation scheme under discontinuous resonant current and continuous resonant current transition modes. This series capacitor compensated for transformer resonant power converter with a high frequency transformer linked voltage boost multiplier can efficiently work a novel selectively-changed dual mode PFM control scheme in order to improve the start transient and steady-state response characteristics and can completely achieve stable zero current soft switching commutation tube filament current dependent for wide load parameter setting values with the aid of two lossless inductor snubbers. It is proved on the basis of simulation and experimental results in which a simple and low cost control implementation based on selectively-changed dual-mode PFM for high-voltage X-ray DC-DC power converter with a voltage multiplier strategy has some specified voltage pattern tracking voltage response performances under rapid rising time and no overshoot in start transient tube voltage as well as the minimized steady-state voltage ripple in tube voltage.

DOI： 10.1541/ieejias.123.649

Soft Switching High Frequency PWM Boost Chopper Type DC-DC Converter with High Boost Voltage Conbersion Ratio

INABA Claudio Y., KONISHI Yoshihiro, HIRAKI Eiji, NAKAOKA Mutsuo

The Transactions of the Institute of Electronics,Information and Communication Engineers B 86 ( 3 ) 599 - 603 2003.3

Two-Paralleled Bridge Type High Frequency PWM Chopper with Multi-Loop Current Feedback Tracking Scheme for Gradient Magnetic Field Controller

WATANABE Shuji, TAKANO Hiroshi, FUKUDA Hiroya, HIRAKI Eiji, NAKAOKA Mutsuo

IEEJ Transactions on Industry Applications 123 ( 3 ) 188 - 195 2003.3

Language：Japanese Publisher：The Institute of Electrical Engineers of Japan

This paper deals the digital optimal current control scheme to improve MRI (Magnetic Resonant Imaging) Gradient-Magnetic Coil (GC) current control implementation. The GC current needs high precision control specifications so as to take clear images with MRI. The novel MRI-GC current control amplifier has the high-frequency PWM chopper circuit with a multi-parallel input structure. The GC current control circuit can prevent the current ripple amplitude and realize high precision GC current controls, but the control system is hard to design because the GC current control circuit has the multi-input and multi-output structure and required high precision control abilities. Therefore, the digital optimal control scheme has tried to apply for the GC current control. The optimal controller is skillful at the design of multi-input and multi-output systems. The novel controller will actualize the high precision GC current controllability because Error System newly includes the GC current error parameter so as to decide the multi-inputs. In this paper, we discuss the novel controller with computer simulations that it can expect the high precision GC current control to improve the image quality of MRI systems.

DOI： 10.1541/ieejias.123.188

Active Auxiliary Edge Resonant Commutation Snubbers Assisted Single Phase Sinewave Inverter with New Switching Sequence-based PWM Pattern

NAKAMURA Mantaro, YAMAZAKI Takayuki, CHANDHAKET Srawouth, AHMED Tarek, HIRAKI Eiji, NAKAOKA Mutsuo

Technical report of IEICE. Energy engineering in electronics and communications 102 ( 643 ) 31 - 36 2003.2

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

This paper presents a new topology of the voltage source bridge inverter circuit which proposes novel active edge resonant snubber circuits using the auxiliary power switches. This inverter is acceptable for an uninterruptible power supply, such as PFC power converter, utility-interactive bi-directional power converter. The soft switching operation principle and design procedure of the active auxiliary edge resonant snubber circuit for the high power applications are described and discussed. Both the main active switches and the auxiliary power switches achieve ZVS or ZCS for this sinewave PWM inverter. In order to minimize the switching surge related electromagnetic noise and the switching power loss of power semiconductor devices used here. This inverter does not need the sensor interfaced circuit to detect the voltage or the current and does not also required for the electrolytic chemical capacitors to make thc neutral point of the DC power supply voltage. Because the power semiconductor switches have the relation of the trade-off evaluations in the switching fall time characteristics and the conductive saturation voltage characteristics, this soft switching inverter can improve efficiency under the conditions of the low saturation voltage.

Performance Evaluations of Dielectric Barrier Discharge Lamp driven by High-Frequency Inverter for Liquid Crystal Backlight

Fujita Kentarou, Tanimatsu Hiroaki, Gamage Laknath, Muraoka Hidekazu, Hiraki Eiji, Nakaoka Mutsuo

Proceedings of Annual Conference of The Illuminating Engineering Institute of Japan 36 17 - 17 2003

Language：Japanese Publisher：The Illuminating Engineering Institute of Japan

In recent years, the CCFL has been used for Liquid Crystal Backlight in Display. From an environmental recycle point of view, the Dielectric Barrier Discharge (DBD) Lamp has attracted special interest in place of the CCFL, the electric equivalent circuit of this lamp is represented by the diode bridge, voltage source, two capacitor capacitances. The measuring method to determine these circuit parameters is described. The low cost high-efficiency voltage resonance high-frequency inverter with a high frequency transformer which is composed of MOSFETs is introduced in order to drive DBD lamp. The dimming control scheme is based on the pulse density modulation technique.

DOI： 10.11515/ieijac.36.0.17.0

共振ACリンクスナバ方式三相電圧形インバータの伝導性・放射性電磁ノイズ評価と検討

吉田正伸, 平木英治, 中岡睦雄, 篠原貞夫, 古川勝彦

電気学会全国大会講演論文集 2003 ( 4 ) 2003

Current-Source Type ZVS-PFM DC-DC Power Converter with High-Frequency High-Voltage Transformer for Magnetron Drive and Its Performance Evaluations

Ishitobi Manabu, Myoi Takeshi, Hiraki Eiji, Nakaoka Mutsuo

Journal of the Japan Institute of Power Electronics 29 ( 2 ) 48 - 53 2003

Publisher：The Japan Institute of Power Electronics

We have considered a voltage-source type series-resonant ZCS-PFM DC-DC Converter in order to drive an industrial-use magnetron for generating high power microwave in advance. This DC-DC converter can achieve a complete zero current soft switching by assist of the transformer parasitic parameter and a lossless inductive snubber. And the output power is regulated over all power ranges without audible frequency range due to the magnetizing current of the high-frequency transformer. However, this DC-DC converter has a weak point that it is easy to oscillate by the parasitic capacitance of the switching device and the lossless inductive snubber. Therefore in this paper, the new topology that can solve that weak point without hurting good characteristics of that converter is proposed and evaluated on the basis of simulation and experimental results.

DOI： 10.5416/jipe2003.29.2_48

CiNii Article

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Utility AC Power Source Connected Sinewave Soft-Switching PWM Inverter with High-Frequency Two-Switch Flyback Transformer Link

Chandhaket Srawouth, Konishi Yoshihiro, Ogura Kouki, Hiraki Eiji, Nakaoka Mutsuo

Journal of the Japan Institute of Power Electronics 29 ( 2 ) 54 - 61 2003

Publisher：The Japan Institute of Power Electronics

This paper presents two novel prototypes of the utility AC power source connected sinewave inverter using the high-frequency two-switch flyback transformer which is more suitable and acceptable for the small-scale solar photovoltaic and fuel cell generator interfaced power conditioners. The proposed sinewave soft-switching PWM power conditioner with a high-frequency AC link has a function of electrical isolation including sinewave hard-switching PWM power conditioner with a high frequency link, which is considered for solar photovoltaic power conditioner and fuel cell generator related power conditioner from the viewpoints of safety and reliability in total system. The discontinuous conduction mode (DCM) operation of the flyback transformer in this circuit system is also introduced to feature a simple, low-cost and high-efficiency topology of the sinewave inverter circuit and digital control implementation. The operating principle of the proposed sinewave soft-switching PWM inverter circuit as compared with sinewave hard-switching PWM inverter are described for the designing of circuit parameters. Moreover, the digitally controlled sinewave PWM control processing scheme is presented herein. Finally, the sinewave soft-switching PWM inverter prototype is actually built and tested to verify the validity of the proposed power conditioner for new energy generation systems.

DOI： 10.5416/jipe2003.29.2_54

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High-Frequency linked Current type ZVS-PFM Parallel Resonant DC/DC Converter.

苗井健, 石飛学, GAMAGE L, 平木英治, 中岡睦雄

電気学会半導体電力変換研究会資料 SPC-03 ( 25-28.30-36 ) 2003

三相電圧形ZVZCS-PWMインバータの特性評価と検討

吉田正伸, 藤井勇馬, 平木英治, 中岡睦雄

電気学会産業応用部門大会講演論文集 2003 ( 1 ) 2003

昇圧チョッパ型入力段を持つ三相電圧形ソフトスイッチングインバータの電力変換効率推定

平木英治, 吉田正伸, 中岡睦雄

電気学会全国大会講演論文集 2003 ( 4 ) 2003

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