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.

Minimum Neutral Clamp Capacitor Design Considering Voltage Saturation for a Three-Level Inverter

Jun-ichi Itoh,Takaaki Tanaka 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

A neutral point clamped inverter has a voltage fluctuation problem at the neutral point capacitor. This paper discusses the minimum value of the neutral point capacitor considering the voltage command saturation with the voltage fluctuation suppression control method. This paper clearly demonstrates the stable relationships among the input voltage, the output voltage and the capacitance value. In addition, the minimization design procedure of the capacitance value basis on this analysis is demonstrated. The validity of the design method is confirmed by experimental results.

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.

Reduction of a Boost Inductance using a Switched Capacitor DC-DC Converter

Jun-ichi Itoh,Koichi Matsuura,Koji Orikawa 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

The loss analysis of a switched capacitor converter (SCC) with a boost reactor is discussed in this paper. The proposed SCC can deliver an output voltage independent from the circuit structure comparing to other voltage control methods. The main feature of this circuit is that most of the energy for the boost up function is transferred from a flying capacitor which results the inductance of the input reactor can be reduced. The reactor size of the proposed SCC is smaller than that of the conventional boost converters. A 1000 W 3-level SCC prototype has been built and tested. The efficiency of 97.8% is achieved at 1000 W when the boost up ratio is three times. Moreover, the loss analysis shows the main loss of the proposed SCC is the diode conduction loss.

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.

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.

Report of the 3rd Japan-Korea Workshop on Acupuncture and EBM;Protocol development for the acupuncture trial on the osteoarthritis of the knee

Jang, Jun-Hyouk,Kenji, Kawakita,Hahn, Seo-Kyung,Park, Hi-Joon,Lee, Seung-Deok,Kim, Yong-Suk,Norihito, Takahashi,Toshiyuki, Shichidou,Kazunori, Itoh,Eiji, Sumiya,Eiji, Furuya,Hitoshi, Yamashita,Hiroshi The Korean AcupunctureMoxibustion Medicine Society 2006 대한침구의학회지 Vol.23 No.6

The 3rd Japan-Korea Workshop on Acupuncture and EBM was held at Kanazawa on June $16^{th}$. From Korea team, 4 papers were presented. Dr. Hahn introduced a new approach of data analysis on series of n-of-1 trials using the Bayesian statistics. It offered important information for the future n-of-1 trials. Dr. Park clearly demonstrated the significance of various sham devices proposed and stressed the importance of research questions when we choose the control intervention in RCT. Dr. Lee reported the results of survey in Korean Medical Doctors (KMD) for their point selection and techniques to the distal and local points. Dr. Kim presented the results of face to face survey on the KMD with 28 items for acupuncture treatment on the knee OA. Finally, a draft of protocol was introduced by Dr. Kim. The title was "multi-center, a randomized, single blinded, two arms, parallel-group study to compare the effectiveness and safety of 'individualized acupuncture' and 'standardized minimal acupuncture' in Korean and Japanese patients with knee osteoarthritis (Phase IV)". From Japan team, 7 speakers presented their comments and proposals on the protocol. Dr. Takahashi introduced several issues regarding n-of-1 trials and pointed out the importance of obtaining generalizability from n-of-1 trials. Dr. Shichidou pointed the importance of research design, selection of outcome measures and reduction of biases. Dr. Itoh presented the results of point selection for the knee OA based on the literature survey. Dr. Sumiya introduced several differences between KMD and Japanese acupuncturists based on the questionnaire used in KMD survey. Dr. Furuya demonstrated a result of press tack needle and its sham device on shoulder stiffness. Dr. Yamashita introduced the results of literature survey regarding adverse events occurred by acupuncture on knee OA. Dr.Tsukayama stressed the importance of responsibility of Institutional Review Board (IRB) for the conduction of clinical trials. After several issues were discussed, the need of continued meeting for final protocol development was agreed, then the workshop was closed.

Atlantoaxial Stabilization Using C1 Lateral Mass and C2 Pedicle/Translaminar Screw Fixation by Intraoperative C1- and C2-Direct-Captured Navigation with Preoperative Computed Tomography Images

Itoh Yasunobu,Kitagawa Ryo,Numazawa Shinichi,Yamakawa Kota,Yamada Osamu,Akasu Isao,Sakai Jun,Otomo Tomoko,Yoshida Hirotaka,Mori Kentaro,Watanabe Sadayoshi,Watanabe Kazuo 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.3

In C1–C2 posterior fixation, the C1 lateral mass and C2 pedicle/translaminar screw insertion under spine navigation have been used frequently. To avoid the risk of neurovascular damage in atlantoaxial stabilization, we assessed the safety and effectiveness of a preoperative computed tomography (CT) image-based navigation system with intraoperative independent C1 and C2 vertebral registration. It is ideal when a reference frame can be linked directly to the C1 posterior arch for C1-direct-captured navigation, but there is a mechanical challenge. A new spine clamp-tracker system was implemented recently, which allows reliable C1- and C2- direct-captured navigation in nine patients with traumatic C2 fractures. In this way, there was no misalignment of C1–C2 screws. C1 lateral mass screws were used except for one case, and translaminar screws were primarily used as an anchor for C2. The C1 lateral mass screw locations, which are 19 mm laterally from the C1 posterior arch’s center, are taken to be constant. However, there is one unusual circumstance in which using a C1 laminar hook instead of a C1 lateral mass screw appears to be a beneficial substitute. The increase of surgical accuracy for posterior C1–C2 screw fixation without cost constraints is significantly facilitated by intraoperative C1- and C2-direct-captured navigation with preoperative computed CT images.

Effects of Root Zone Volume on Flower Initiation of Tomato Seedlings under Different Temperature Regimes

Miki Nakata,Jun Itoh,Cyd Celeste. Cagas,Nobuo Sugiyama 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Emerging evidence for crosstalk between Nrf3 and mitochondria in physiological homeostasis and in heart disease

Michiko Tsushima,Jun Liu,Wataru Hirao,Hiromi Yamazaki,Hirofumi Tomita,Ken Itoh 대한약학회 2020 Archives of Pharmacal Research Vol.43 No.3

Nrf2 regulates redox homeostasis in cells bycoordinately regulating a range of antioxidant enzymes andproteins. An increase in oxidative stress is one of the hallmarksof aging, and Nrf2 protein levels and activity decreasewith aging. Decreased mitochondrial functions, such asdecreased ATP production, also occur with aging, leadingto the increased generation of reactive oxygen species (ROS)and oxidative stress. Thus, understanding the relationshipsbetween Nrf2 and the mitochondria is important for clarifyingthe regulatory mechanisms of aging. It is becomingclear that Nrf2 is activated in a tissue-specific manner inresponse to mitochondrial or NADPH oxidase-generatedROS. As the heart consists of postmitotic cells that utilizeATP produced mainly by mitochondrial oxidative phosphorylation,cardiomyocytes are equipped with highly sophisticatedmitochondrial quality control mechanisms. Consistentwith these findings, it has been reported that Nrf2 inthe heart is regulated via a specific translational mechanismand that Nrf2 activation confers cardioprotective effects invarious disease models. Thus, Nrf2 is a promising target foranti-aging strategies to combat age-related heart diseases,such as age-related cardiomyopathy.