著者
小島 立寛 和田 圭二 五箇 繁善
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌D(産業応用部門誌) (ISSN:09136339)
巻号頁・発行日
vol.142, no.8, pp.647-648, 2022-08-01 (Released:2022-08-01)
参考文献数
5

This paper proposes that wireless time synchronization by GNSS (Global Navigation Satellite System) can be applied to the control of power conversion circuits, and clarifies its validity through experiments. This paper shows that a highly accurate synchronization can be obtained by employing a synchronization system based on GNSS. Moreover, the control signals of each power device in a half-bridge inverter are connected to a controller with GNSS and driven using 10kHz switching, which enables operation of the power conversion circuit without causing a leg short circuit.
著者
関口 貴哉 和田 圭二 清水 敏久
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌D(産業応用部門誌) (ISSN:09136339)
巻号頁・発行日
vol.142, no.7, pp.498-505, 2022-07-01 (Released:2022-07-01)
参考文献数
27

This study proposes a novel active power decoupling (APD) control method focusing on the power generation characteristics of photovoltaic (PV) arrays. Numerous studies have been conducted on the APD method for achieving a long lifetime of a residential PV power generation system. The APD method reduces the power pulsation, which contains twice the utility frequency caused by a single-phase PV inverter. Compared with the passive power decoupling method using electrolytic capacitors, the APD method incurs power conversion loss due to the increase in passive components and power devices. Many studies have considered the efficiency improvement of the APD method, however most of them focus on the power conversion loss of the APD circuit. It is necessary to consider the power conversion efficiency of the power conditioner and the power generation efficiency of the PV array collectively to improve the efficiency of the PV system. Therefore, in this study, a compensation power control for APD circuit focusing on the power generation characteristics of the PV array is proposed, and the validity of the proposed APD control was verified by evaluating the efficiency based on real-time simulation and experimental results of a 1kW power conditioner.
著者
林 真一郎 和田 圭二
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌D(産業応用部門誌) (ISSN:09136339)
巻号頁・発行日
vol.136, no.10, pp.791-797, 2016-10-01 (Released:2016-10-01)
参考文献数
34
被引用文献数
3 3

This paper discusses the influences of common source inductance in power converter circuits. Common source inductance is the source-side inductance inside a power module, and it shares common circuit parameters with both the gate drive and power circuit. Therefore, common source inductance will influence the switching characteristics of the module. No paper has yet addressed the relationship between common source inductance and switching characteristics such as surge voltage and switching loss. In order to improve the switching characteristics during turn-off operations, this paper presents a design procedure with respect to common source inductance. In addition, experimental results rated at 500V, 40A are shown.
著者
三井 晃司 和田 圭二
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌D(産業応用部門誌) (ISSN:09136339)
巻号頁・発行日
vol.140, no.11, pp.817-825, 2020-11-01 (Released:2020-11-01)
参考文献数
45
被引用文献数
1

In a power converter circuit, it is well known that the bus bar structure affects both surge voltage and switching loss. However, the bus bar structure may be one of the causes for the oscillation waveform to induce electromagnetic interference (EMI) issues. This study proposes a design procedure of an optimized bus bar structure. Since the parasitic parameters of the bus bar geometory, such as inductance, capacitance, and resistance, are complicated in the megahertz frequency range, the parasitic parameters that have frequency characteristics are analyzed by the finite element method. The surge voltage and oscillation voltage under a turn-off operation are evaluated by using the bus bar modeled as S-parameters. It demonstrated that the optimal bus bar structure can reduce the surge voltage and oscillation. In accordance with the method to design an optimal bus bar, bus bar prototypes are designed, and the experimental results rated at 400V, 30A are presented to verify the analysis and simulation.
著者
松原 壱樹 和田 圭二 鈴木 敬久
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌D(産業応用部門誌) (ISSN:09136339)
巻号頁・発行日
vol.142, no.2, pp.95-103, 2022-02-01 (Released:2022-02-01)
参考文献数
41

There has been an increasing interest in biological effects owing to magnetic field exposure, because wireless power transfer systems for electric vehicles are expected to be widespread in the 85kHz band. Therefore, it is necessary to develop a magnetic field generator and evaluate the biological effects through experimental verification. In particular, the exposure area needs to be expanded for the development of magnetic field generators to offer sufficient number of exposure subjects. This paper presents the design procedure of a two-winding inductor for expanding the exposure area of a magnetic field generator. Two-winding inductors connected in series and in parallel are shown, and circuit configurations using these inductors are presented. It is revealed through impedance analysis that the difference in circuit parameters restricts the operable frequency band in a magnetic field generator with a two-winding inductor connected in parallel. The two-winding inductor connected in parallel can expand the exposure area to 321% of that of a conventional magnetic field generator. Moreover, the validity of impedance analysis is confirmed through the experimental verification rated at 100V.
著者
高橋 翔太郎 和田 圭二
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌D(産業応用部門誌) (ISSN:09136339)
巻号頁・発行日
vol.142, no.1, pp.33-40, 2022-01-01 (Released:2022-01-01)
参考文献数
21
被引用文献数
1

In this study, the authors propose a simple method for estimating stray capacitance of toroidal inductors. The proposed method calculates the total stray capacitance of a toroidal inductor based on the stray capacitance between the winding and the core, calculated by considering the insulation (plastic case and plastic molding) that contains the magnetic core. The frequency characteristics of the toroidal inductor can be calculated by substituting the calculated stray capacitance in the analytical model of the inductor, which takes into account the frequency dependence of the complex magnetic permeability of the magnetic material. In order to evaluate the proposed method, toroidal inductors were fabricated based on carbonyl iron dust, amorphous and nanocrystalline magnetic cores. Comparison between measured and calculated impedances clarify that the proposed method can calculate the stray capacitance of toroidal inductors with practical accuracy.
著者
徳山 寛 和田 圭二 五箇 繁善
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌D(産業応用部門誌) (ISSN:09136339)
巻号頁・発行日
vol.141, no.4, pp.324-329, 2021-04-01 (Released:2021-04-01)
参考文献数
21

In power converter circuits, a gate drive circuit is connected to the power devices for the switching operation. The gate drive circuit transmits both signal and power to the power devices, simultaneously. At present, multi-level converter circuits using large numbers of devices have been proposed for power electronics circuits, but these are complicated to implement in a circuit. Hence, simplification of the signal and power transmissions of the gate drive circuit is required for circuit implementations. This paper proposes a gate drive circuit using SAW (Surface Acoustic Wave) devices that can transmit signal and power to the power devices, simultaneously. To use the several-hundreds MHz signal output from the SAW filter as the gate signal, this paper presents the design procedure for the internal parameters of the detection circuit that demodulates the signal into a several kHz signal. The usefulness of the proposed design is demonstrated by experimental evaluation of a half-bridge inverter and gate drive circuit with SAW filters.
著者
和田 圭二 平尾 高志
出版者
一般社団法人 電気学会
雑誌
電気学会論文誌D(産業応用部門誌) (ISSN:09136339)
巻号頁・発行日
vol.139, no.8, pp.765-766, 2019-08-01 (Released:2019-08-01)
参考文献数
4

This letter proposes a single-phase full-bridge inverter with a capacitor embedded in a bus bar. In order to reduce the switching ripple flowing in the electrolytic capacitor, the proposed structure embeds a barium titanate (BaTiO3) ceramic capacitor in the bus bar. The experimental results verified the operation of the inverter circuit, rated 300V, 4.1A with a switching frequency of 100kHz.
著者
和田 圭二
出版者
首都大学東京
雑誌
若手研究(B)
巻号頁・発行日
2006

分散型電源の代表である太陽光発電が国内をはじめ欧米諸国において急速に普及している。そのため,配電系統にインバータが多数接続されるようになってきた。本研究課題では,太陽光発電用インバータが複数台接続された場合における,伝導ノイズの発生状況とノイズフィルタの設計手法について研究を行った。また,複数台インバータのスイッチング手法についても検討を行った。主となる研究対象は,50W〜100W程度の太陽電池モジュールの背面に接続するACモジュールと呼ばれる太陽光発電の方式とした。この方式の場合には,20〜30台の小容量(50W〜100W)のインバータが同時に動作するために,伝導ノイズの発生量がインバータの動作状態やフィルタの接続法によって大幅に変化する可能性がある。まず,2台のフライバックインバータ同時動作の場合について研究を行い,インバータのスイッチングのタイミングを180度ずらすことによって,ノイズ成分が等価的に2倍になることを実験により明らかにした。一方,複数台インバータを非同期でスイッチングさせることによって特別な制御を用いることなくノイズ発生量を低減できることを示した。また,ノイズフイルタの設計では,フィルタの寄生容量を考慮して設計を行い,各インバータにノイズフィルタを設置するよりも-括設置することによって伝導ノイズを効果的に低減可能であることを解析と実験により明らかにした。以上の結果は,今後予想されるインバータ複数台動作時におけるノイズ抑制手法に関するフィルタ設計法の指針を与えるものであり,分散電源装置のさらなる普及・促進のための重要な研究成果を得ることができた。