A Transformerless Hybrid Active Filter for Integration into a Medium-Voltage Motor Drive with a Passive Front End

Hirofumi Akagi 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

This paper discusses a transformerless hybrid active filter integrated into the 6.6-㎸, 1-㎿ adjustable-speed motor drive having a three-phase diode rectifier at the front end. The hybrid filter consists of an active filter using a threelevel diode-clamped PWM converter rated at 60 ㎸A, and a 250-㎸A passive filter tuned to the 7th-harmonic frequency. They are directly connected in series without transformer. This circuit configuration enables to use 1.2-㎸ IGBTs because the dc voltage of the three-level converter is 1.32 ㎸ (20% of 6.6 ㎸). Voltage-balancing control characterized by superimposing a 6thharmonic zero-sequence voltage on the active-filter voltage reference in each phase is introduced to the three-level converter with triangle-carrier modulation. Experimental waveforms obtained from a 400-V 15-㎾ down-scaled system verify the viability and effectiveness of the proposed hybrid filter, keeping the two dccapacitor voltages balanced well.

Present State and Future Trends of Active Power Filters in Japan

Hirofumi Akagi,Noriyuki Watanabe 전력전자학회 1992 ICPE(ISPE)논문집 Vol.1992 No.4

With remarkable development and advance in PWM inverter technology on the basis of fast switching devices in the 1980s, active power filters which are classified into shunt and series active filters have been studied with the focus on their practical installation in industrial power systems. In 1982, a shunt active filter of rating 800kVA was put into practical use for the first time in the world. The main circuit consisted of a current source PWM inverter using GTO thyristors. In 1986, a combined system of a shunt active filter of rating 900kVA and a shunt passive fil­ter of rating 6600kVA was practically installed to suppress the harmonics produced by a large capacity cycloconverter for steel mill drives.<br/> More than one hundred shunt active filters have been operating properly in Japan. The largest one of the shunt active filters is 20MVA, which was developed in 1990 for reactive power and harmonic compensation for an arc fur­nace with the help of a shunt passive filter of 20MVA.<br/> This paper presents a survey of shunt and series active filters using PWM inverters, paying attention to research and practical applications in Japan.<br/>

Effect of Annealing Temperature on Magnetic Properties of Dust Cores

Mitani Hiroyuki,Akagi Nobuaki,Houjou Hirofumi,Kanamaru Moriyoshi 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

Magnetic Properties of dust cores made of mixtures of atomized pure iron powder and pure alumina powder has been investigated in the temperature range from 673 to 1073K. The effect of annealing on coercivity has been positive effect up to 973K and thus coercivity is gradually reduced form 280A/m (as-compressed) to 160A/m (973K). However, dust cores annealed at 1073K displayed a 15% increasing of coercivity by annealing at 973K. Hysteresis loss shows a tendency similar to coercivity. Microstructure observation of specimens shows grain refinement by recrystallization in the temperature range from 773 to 1073K.

Low-Speed Rated-Torque Operation of a Motor Drive Using a Five-Level Diode-Clamped PWM Inverter with a Front-End Diode Rectifier

Kazunori Hasegawa,Hirofumi Akagi 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper focuses on a medium-voltage motor drive requiring no regenerative braking. It is operated not only in a high-speed region but also in a low-speed region with the rated torque, intended for an application to drilling rigs. The power conversion system consists of a front-end diode rectifier, a five-level diode-clamped PWM inverter, and a dc-voltage-balancing circuit including a single coupled inductor. The five-level diode-clamped inverter is characterized by injecting a common ninth-harmonic zerosequence voltage on each of the three-phase reference voltages for mitigating magnetic-flux fluctuation of the coupled inductor of the dc-voltage-balancing circuit. Moreover, the voltage injection can make the power-loss distribution of eight insulated gate bipolar transistors (IGBTs) per leg close to an even profile. Experimental results obtained from a 200-V 5.5-㎾ downscaled model confirm the viability and effectiveness of the power conversion system, indicating that the ninth-harmonic zero-sequence voltage injection mitigates the magnetic-flux fluctuation.

Reduction of EMI Generated by a PWM Inverter-Fed AC Motor Drive System

Satoshi Ogasawara,Hirofumi Akagi 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-

This paper deal with problems of leakage current, shaft voltage, bearing current, and EMI, in valiable-speed AC drives. The originating mechanism is illustrated with a high-frequency equivalent circuit. Re­duction methods are classified in to six categories based on the equivalent circuit. Some experimental results show that a common-mode transformer (CMT) and a common-noise canceler (ACC) can solve the problems, which have been proposed by the authors.<br/>

Which is More Suitable for MMCC-Based Medium-Voltage Motor Drives, a DSCC Inverter or a TSBC Converter?

Yuhei Okazaki,Wataru Kawamura,Makoto Hagiwara,Hirofumi Akagi,Takashi Ishida,Masahiko Tsukakoshi,Ritaka Nakamura 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper provides theoretical, numerical, and experimental comparisons in electrical-drive performance between a double-star chopper-cells (DSCC) inverter and a triplestar bridge-cells (TSBC) converter. The inverter and converter are two of the most promising members of the modular multilevel cascade converter (MMCC) family. Two sets of downscaled electrical drives using the DSCC inverter and the TSBC converter are designed, constructed, and tested, along with the common three-phase four-pole induction motor rated at 380 V, 15 kW, and 50 Hz. This paper presents experimental waveforms of the electrical drives loaded with a quadratic torque-to-speed profile and at the rated torque.

Topology and Application of Bidirectional Isolated DC-DC Converters

Nadia M. L. Tan,Takahiro Abe,Hirofumi Akagi 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

A bidirectional isolated dc-dc converter manages the power flow between an energy storage device and a dc bus with functions of galvanic isolation and voltage matching. Research and development of these converters focus on improving efficiency and power density. This paper presents and compares various configurations of bidirectional isolated dc-dc converters. It also illustrates the performance of a 6-㎾, full-bridge, bidirectional isolated dc-dc converter operating at 4 ㎑, which is suitable for output power leveling of photovoltaic generation systems connected to homes and office buildings. The maximum efficiency of the dc-dc converter is measured at 98.1% during battery charging and at 98.2% during battery discharging. The converter maintains a high efficiency of more than 97% for a wide range of power transfer.

Model Predictive Control of Bidirectional AC-DC Converter for Energy Storage System

Akter, Md. Parvez,Mekhilef, Saad,Tan, Nadia Mei Lin,Akagi, Hirofumi The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

Energy storage system has been widely applied in power distribution sectors as well as in renewable energy sources to ensure uninterruptible power supply. This paper presents a model predictive algorithm to control a bidirectional AC-DC converter, which is used in an energy storage system for power transferring between the three-phase AC voltage supply and energy storage devices. This model predictive control (MPC) algorithm utilizes the discrete behavior of the converter and predicts the future variables of the system by defining cost functions for all possible switching states. Subsequently, the switching state that corresponds to the minimum cost function is selected for the next sampling period for firing the switches of the AC-DC converter. The proposed model predictive control scheme of the AC-DC converter allows bidirectional power flow with instantaneous mode change capability and fast dynamic response. The performance of the MPC controlled bidirectional AC-DC converter is simulated with MATLAB/Simulink(R) and further verified with 3.0kW experimental prototypes. Both the simulation and experimental results show that, the AC-DC converter is operated with unity power factor, acceptable THD (3.3% during rectifier mode and 3.5% during inverter mode) level of AC current and very low DC voltage ripple. Moreover, an efficiency comparison is performed between the proposed MPC and conventional VOC-based PWM controller of the bidirectional AC-DC converter which ensures the effectiveness of MPC controller.

Stability and Performance Investigations of Model Predictive Controlled Active-Front-End (AFE) Rectifiers for Energy Storage Systems

Akter, Md. Parvez,Mekhilef, Saad,Tan, Nadia Mei Lin,Akagi, Hirofumi The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

This paper investigates the stability and performance of model predictive controlled active-front-end (AFE) rectifiers for energy storage systems, which has been increasingly applied in power distribution sectors and in renewable energy sources to ensure an uninterruptable power supply. The model predictive control (MPC) algorithm utilizes the discrete behavior of power converters to determine appropriate switching states by defining a cost function. The stability of the MPC algorithm is analyzed with the discrete z-domain response and the nonlinear simulation model. The results confirms that the control method of the active-front-end (AFE) rectifier is stable, and that is operates with an infinite gain margin and a very fast dynamic response. Moreover, the performance of the MPC controlled AFE rectifier is verified with a 3.0 kW experimental system. This shows that the MPC controlled AFE rectifier operates with a unity power factor, an acceptable THD (4.0 %) level for the input current and a very low DC voltage ripple. Finally, an efficiency comparison is performed between the MPC and the VOC-based PWM controllers for AFE rectifiers. This comparison demonstrates the effectiveness of the MPC controller.

Stability and Performance Investigations of Model Predictive Controlled Active-Front-End (AFE) Rectifiers for Energy Storage Systems

Md. Parvez Akter,Saad Mekhilef,Nadia Mei Lin Tan,Hirofumi Akagi 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1

This paper investigates the stability and performance of model predictive controlled active-front-end (AFE) rectifiers for energy storage systems, which has been increasingly applied in power distribution sectors and in renewable energy sources to ensure an uninterruptable power supply. The model predictive control (MPC) algorithm utilizes the discrete behavior of power converters to determine appropriate switching states by defining a cost function. The stability of the MPC algorithm is analyzed with the discrete z-domain response and the nonlinear simulation model. The results confirms that the control method of the active-front-end (AFE) ectifier is stable, and that is operates with an infinite gain margin and a very fast dynamic response. Moreover, the performance of the MPC controlled AFE rectifier is verified with a 3.0 kW experimental system. This shows that the MPC controlled AFE rectifier operates with a unity power factor, an acceptable THD (4.0 %) level for the input current and a very low DC voltage ripple. Finally, an efficiency comparison is performed between the MPC and the VOC-based PWM controllers for AFE rectifiers. This comparison demonstrates the effectiveness of the MPC controller.