Faculty of Engineering
Doctor of Eng. / Professor
Electrical Eng. Dept., Fac. of Eng. Osaka University, Japan, 1976.
Electrical Eng. Course., Graduate school of Eng. Osaka University, Japan, 1978.
Ph.D. degrees in electrical engineering from Osaka University, Japan, 1993.
Central Research Laboratory of Mitsubishi Electric Co.Ltd., Hyogo, Japan.
Research associate at the Department of Electrical Engineering of Osaka University.
Associate professor (1994-2003) and professor (2003-2020) at the Department of Electrical and Electronic Systems Engineering of Osaka Inst. of Technology.
Power system analysis and simulation, HVdc transmission, high power converter, power electronics system analysis and simulation and its control.
The solid state transformer applied for the HVDC transmission from the offshore windfarm has been investigated. The 5kVA experimental setup is developed and comparison of up to 1200Hz operation. Dependency of the loss in the transformer with different core materials to frequency is investigated. Frequency loss dependency of nano-crystaline and amorphous core materials are compared in experimental measurement. Nanocrystaline material called “FINEMET” is the best performance, although amorphous seems to have better cost performance. It is also indicated that the converter voltage causes the larger loss in the transformer than the sinusoidal power supply.
Fig. 1 shows the schematic diagram of HVDC transmission using SST. It is expected to have 1/100 volume at 100kHz frequency compared with 50/60 Hz conventional transformer. In this NEDO project, the converter system and the middle frequency (MF) transformer will be developed by our institute to realize the large rating solid-state transformer (SST).
Fig. 2 shows the configuration of the solid state transformer (SST) experimental setup. MF-TR is middle frequency transformer (5kVA, 3kHz). VSC1 is conventional 3-phase converter. VSC2 is 3-phase modular multi-level converter with half bridge cell (MMC-DSCC).
Fig. 3 shows the efficiency of MF-transformer in SST depending on the input power at 1000Hz. FINEMET (Nano-crystaline) core material shows the better efficiency than the amorphous core material. Both results of manufacturer A and B show the similar dependency.
Experimental results show that the MMC based SST can be operated stably at the middle frequency.
Core materials are compared in efficiency and the cost. It is interesting that the higher frequency shows the better efficiency around 1kHz, 1kW operation.
The amorphous has good cost performance, though the nano-crystaline “FINEMET” has the better efficiency than the amorphous. However, the difference is not so large at 1kHz, and the amorphous core may have the better cost performance.
Toshimitsu Morizane, Noriyuki Kimura, Katsunori Taniguchi, “Analysis of Power Control Characteristics of Induction Generator System with Voltage Source Converter for Wind Power Generation”, IEEJ Transaction-B, No.2, Vol.132, 2012.
Noriyuki Kimura, Akira Kouno, Toshimitsu Morizane, Katsunori Taniguchi, “Suppression of Harmonics for BTB HVdc connection using Multi-Level Converter”, IEEJ Transaction-B, 122-B, No.2, pp.1706-1712, 2002.2.
“Ace Power Electronics”, Takashi Hikihara, Noriyuki Kimura, Akira Chiba, Syunsuke Ohashi, Asakura Publishing Co., Ltd., Apr. 2000.
“OHM University Text: Electric Power System Engineering”, Ishigame, Miyauchi, Kimura, Taoka, Sugihara, Iyoda, Ohmsha Ltd., Dec. 2013.