FRT Operation for Single-Phase Grid-Tied Inverter with Active Power Decoupling Capability

Jun-ichi Itoh,Satoshi Nakamura,Satoshi Nagai,Hiroki Watanabe 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper proposes a Fault Ride-Through (FRT) operation for a single-phase grid-tied inverter with an active power decoupling capability. The power decoupling circuit achieves the double-line-frequency power pulsation compensation with a small capacitance; consequently, a transient response with a sudden load change becomes worsen because a large energy buffer, i.e. bulky electrolytic capacitors, does not apply. In particular, high overshoot voltages occur in a DC-link voltage when the grid voltage sag of the single-phase grid occurs, resulting in the interrupt of the FRT operation due to the over voltage protection. In order to solve this problem, the buffer capacitance is designed in the consideration of the overshoot amount of the DC-link voltage. The theoretical value of the overshoot amount is verified with a 1-kW prototype. As an experimental result, The error between the experimental and the calculation value is within 10%. Furthermore, the proposed control achieved both the FRT operation and the active power decoupling capability.

Breakthrough Rate of Alkali Metal Halide in Gaseous or Fine Particulate Form by Glass Fiber Filter

( Jun-ichi Kagotani ),( Nobuhisa Watanabe ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-

After an accident of nuclear power plant, volatile cesium (Cs) were released to atmosphere and polluted various things. Some of waste contaminated with radioactive Cs were to be incinerated however those facilities are not built for the processing of radioactive waste. Bag filter (filtration type dust-collector) is a system, which is collects gaseous pollutants and particulate matter after injection of slaked lime in a gas. Although it has been reported that radioactive Cs can be removed more than 99.9% trapping mechanism with a bag filter equipped in solid waste incinerators and effect of injection of slaked lime should be furthermore studied. The paper is focused on collecting efficiency of NaCl, KCl and CsCl by glass fiber filter with or without slaked lime coating.

Voltage Control Method in Non-linear Dead-time Effect Region for Dual Active Bridge DC-DC Converter

Jun-ichi Itoh,Kengo Kawauchi,Hayato Higa,Hiroki Watanabe,Keisuke Kusaka 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper proposes a voltage control method for a Dual Active Bridge (DAB) converter with three-level operation in the dead-time effect region. The non-linear transmission power error is reduced by controlling the zero current phase to the dead-time or more because the nonlinear error of the transmission power occurs when the inductor current reaches zero during the dead-time. In addition, the voltage control is operated under the linear region which is decided from the output current and the zerovoltage period. The validation of the proposed method is confirmed by a 2.3-kW prototype. In the experiments, the non-linear error in the transmission power is reduced by 76.3%. The linearity between a control variable and an output current is confirmed. In addition, a load step between two modes of three-level operation is achieved without the dc offset in the inductor current. Moreover, the RMS value of the inductor current is reduced by 50.2% compared with the conventional triangular modulation.

Design of Flux-Axis Angular Speed Estimation using Induced Voltage in Speed Sensor-less Field Oriented Control for Induction Motor

Jun-ichi Itoh,Kazuya Kawai,Koroku Nishizawa,Hiroki Watanabe 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper proposes a design method of the flux-axis angular speed estimation using induced voltage in a speed sensor-less field oriented control for induction motor (IM) drive systems. In this method, the d-axis induced voltage is regulated to zero by a feedback control to estimate the fluxaxis angular speed. A low pass filter (LPF) is necessary in this estimation to avoid the recursive calculation. In this paper, the design method of compensation gain kpem and the cut-off angular frequency of LPF ωlpf are considered. As a result, the relation between kpem, ωlpf, convergence time of the d-axis induced voltage have a match to the equation and designed model in this paper. Furthermore, the maximum error between the simulation and estimated results of the time constant of the flux-axis angular speed introduced due to LPF is 3.7% when ωlpf is 200 rad/s. As the experimental results, when a torque step of 100% is applied to the induction motor, the convergence time of the motor speed is 1.6 s as the worst case with kpem set as 2.0 p.u. and the cut-off angular frequency set as 1000 rad/s. However, if kpem is set as 2.0 p.u. and ωlpf is set as 400 rad/s, the convergence time of the motor speed is 0.43 s as the best case, which is reduced by 73.1% compared to the worst case. As the result, kpem should decide by the target steady-state error, lpf should bigger than the cut-off angular frequency of the PI controller ωASR. Where, if the ωlpf is high, the convergence time of the motor speed is high.

Voltage Unbalance Compensation Method with Zero Voltage Switching for Series Connected Switching Devices

Jun-ichi Itoh,Ryosuke Iso,Hiroki Watanabe 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper proposes a voltage unbalance compensation method of series-connected switching devices for high voltage application such as DC distribution systems. In the series connection, a turn-off voltage unbalance occurs in switching devices due to a parasitic parameter mismatch and a switching timing mismatch among switching devices. In this paper, a capacitor snubber and Zero Voltage Switching (ZVS) operation are utilized to reduce voltage unbalance. In particular, the proposed method reduces the parasitic capacitor (collector-emitter capacitance) mismatch among series-connected devices by a capacitor snubber circuit, whereas the switching losses are effectively reduced by ZVS. As the simulation results, it is confirmed that the collector-emitter voltage unbalance is reduced by 88% by the proposed method in comparison with a snubber-less configuration. Finally, in order to confirm the effectiveness of the proposed method, experiments with a test circuit applied with the proposed method are conducted. According to the experimental results, the voltage unbalance is reduced by 86.0% due to the application of the proposed method.

2007 Outburst of 17P/Holmes: the Albedo and the Temperature of the Dust Grains

Masateru ISHIGURO,Jun-ichi WATANABE,Daisuke KURODA,YukiS ARUGAKU 한국천문학회 2009 天文學會報 Vol.34 No.2

Association Study of Fat-mass and Obesity-associated Gene and Body Mass Index in Japanese Patients with Schizophrenia and Healthy Subjects

Shin-ya Watanabe,Jun-ichi Iga,Shusuke Numata,Masahito Nakataki,Toshihito Tanahashi,Mitsuo Itakura,Tetsuro Ohmori 대한정신약물학회 2012 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.10 No.3

Objective: Fat-mass and obesity-associated (FTO) gene is known to be involved in the pathophysiology of obesity and a single-nucleotide polymorphism (SNP) rs9939609 of FTO gene is repeatedly confirmed to be associated with body mass index (BMI) and obesity. The aim of this study is to elucidate effects of FTO gene polymorphism on BMI in Japanese patients with schizophrenia and healthy subjects. Methods: Three hundred fifty one patients with schizophrenia and 342 age- and sex- matched healthy subjects participated in the study. Information on BMI and antipsychotic medication was also collected from patients and healthy subjects. Genotype of the FTO SNP rs9939609 was determined by TaqMan SNP Genotyping Assays. Results: There was no significant difference in BMI between patients and healthy subjects. No significant difference in BMI was observed among any medications. We observed no significant difference in rs9939609 allele frequencies between patients and healthy subjects. There was a significant difference in BMI between healthy subjects with risk (AA or TA) genotypes and those with TT genotype. We also observed a significant positive correlation between the number of risk allele (A allele) and BMI in healthy subjects. Conclusion: Our study suggested that FTO rs9939609 polymorphism might have some impacts on the BMI in healthy subjects,but might not have same impacts on the BMI of patients with schizophrenia.

Analysis of Current Control Bandwidth in Current Source Type Motor Emulator

Gensui Tanaka,Katsuki Miura,Keita Ohata,Hitoki Watanabe,Jun-ichi Itoh,Ikuya Sato 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

This paper focus on the stability issue of an inverter test system with a current source type motor emulator (CSTME). The CSTME imitates various motor operations with accuracy. However, the CSTME requires high current control bandwidth to prevent interference between the current controls of both the inverter under test (IUT) and the CSTME. This paper reveals the required current control bandwidth, which is to prevent interference between current controls, based on root locus analysis results. From the result of the stability analysis, the current controller of the CSTME requires 2.2 times higher bandwidth than IUT’s bandwidth. The stability limit of the root locus analysis agrees with the simulation of the time domain. In addition, the effect to the stability limit with time delay is also investigated. Then, the CSTME’s required current control bandwidth becomes more than 3.1 times of that of IUT. The validity of the analysis is verified by the simulation on the time domain.

Wide Range Multi-level DC-DC Converter with TCM for High Voltage Applications

Takashi Ohno,Rintaro Kusui,Hiroki Watanabe,Jun-ichi Itoh,Takuya Kataoka 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

This paper proposes a control method based on Triangular Current Mode (TCM) for a Current-Fed Dual Active Bridge (DAB) converter, which uses a three-level flying capacitor converter in order to accept high voltage(1500V) output. The proposed control method achieves the high-efficiency region in a wide operation range. Additionally, the proposed control performs the Zero Voltage Switching in a wide operation range. Also, the TCM is controlled at a variable frequency to keep the negative current constant. As a result, the operation range is limited because the switching frequency of the power converter is often applied to several kilo-Hz in high-power applications. In order to solve this problem, this paper also proposes that the full-bridge and half-bridge operation is adopted using the multi-level flying capacitor configuration. In the experimental results, the operation range of the proposed control is extended by 70% compared to that of the conventional Current-Fed DAB converter.

Switched flyback PFC converter for wide AC input voltage range

Yuki Kawai,Naoto Kikuchi,Hiroki Watanabe,Keisuke Kusaka,Jun-ichi Itoh 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

This paper proposes a switched flyback PFC converter for a universal input range applications. Conventional controllers have large number of components to realize the wide range voltage input, which reduces the efficiency. The proposed converter supports worldwide power supplies by two flyback converter and two additional switches. The proposed converter is based on two flyback converters and switches the connections of them in series or parallel according to the input voltage. Moreover, the proposed circuit is driven by the Triangular Current Mode (TCM) with variable frequency (VF) to achieve zero-voltage switching (ZVS). However, the VF causes the input current distortion because the input current is not proportional to the input voltage by changing the duty ratio. Therefore, this paper proposes the compensation method of the input current distortion using the TCM. The fundamental operation is demonstrated by the simulation and experiment. As the simulation result, it was confirmed that the input current distortion was improved by 99.2%. In the experimental result, the proposed circuit drives the power factor of 99.9 % by 1.0 p.u. in DCM operation.