Simultaneous Estimation of the Speed and the Secondary Resistance under the Transient State of Induction Motor

Kan Akatsu,Atsuo Kawamura 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-

In the speed sensorless control of the in­duction motor, the machine parameters (especially the secondary resistance R_2) have a strong influence to the speed estimation. It is known that the simultaneous es­timation of the speed and R_2is impossible in the slip frequency type vector control, because the secondary flux is constant. But the secondary flux is not always constant In the speed transient state. In this paper the R_2estimation in the transient state without adding any additional signal to the stator current is proposed. This algorithm uses the least mean square algorithm and the adaptive algorithm, and it is possible to estimate the R_2 exactly. This algorithm is verified by the digital simula­tions and the experiments.<br/>

High voltage driving method by using cluster inverters for SRM

K. Miyane,K. Akatsu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In this paper, a high voltage driving method using low rated voltage devices for Switched Reluctance Motors (SRM) is proposed. In conventional driving circuit for SRM an asymmetrical H-bridge inverter is usually used, the maximum motor voltage depends on the rated voltage of the switching device. Then, the demand of increasing the motor voltage due to increasing rotational speed results to increase the inverter cost because higher rated voltage power device should be used. To solve this problem, a cascade conventional asymmetrical H-bridge circuit to drive SRM is proposed. In this circuit, since half voltage of the conventional circuit voltage is applied to the switching device, the maximum applied voltage can be expanded as twice as it of the conventional circuit. In this paper, the proposed circuit is expressed and its effectiveness is verified by the simulation and the experiment.

A new SRM drive method by using current source inverter

Gaku Ando,Kan Akatsu 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper presents new SRM drive method by using the current source inverter. A problem that huge induced voltage is generated by using the current source inverter is solved by the proposed inverter circuit which has a voltage clamp circuit. The simulation results and the experimental results show that the induced switch voltage is reduced in the clamped circuit.

Initial Impact of the COVID-19 Outbreak on ADHD Symptoms Among University Students in Japan

Takeda Toshinobu,Tsuji Yui,Akatsu Reiko,Nomura Tatsuya 대한소아청소년 정신의학회 2023 소아청소년정신의학 Vol.34 No.2

Objectives: The coronavirus disease 2019 pandemic and its associated societal responses are anticipated to have wide-ranging effects on youth development and mental health. Depression, anxiety, and attention deficit hyperactivity disorder (ADHD) are the three most common mental health problems among university students. Many factors that can threaten mental health during the outbreak affect these three conditions, as well as sleep conditions, in undergraduate students. Thus, determining how these abrupt changes in students’ circumstances impact their mental health is very important from a public health perspective. Methods: We investigated the usual conditions and changes in ADHD symptoms during the outbreak, in relation to depressive and sleep-related symptoms among undergraduate students. A total of 252 students, primarily juniors, completed the online survey. Results: The results showed that 12% of the students exceeded the cut-off score of the ADHD questionnaire before the pandemic. Approximately 6%–21% of the university students, especially those with ADHD traits, rated their ADHD behaviors as worse during the outbreak than that before the outbreak. Conclusion: Female students and undergraduates with ADHD traits are more susceptible to experiencing further deterioration of ADHD (inattention) symptoms during the pandemic. In cases where it is difficult to intervene with ADHD symptoms, approaching circadian rhythm or depression will be of considerable clinical use.

Investigation of current measurement method of bonding wire by using GMR sensor

Tatsuru Tamori,Kan Akatsu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Recently, a miniaturization of the inverter module in the drive system is proceeding. One of the problems of the miniaturization of the inverter module is the heat generation density increase as the inverter module becomes smaller. Since a bonding wire in the inverter module is disconnected due to heat, it is necessary to early detect the disconnection for the protection of the system. In this research, by setting a GMR sensor under the bonding wire in the inverter module, we propose a small inverter module with a built-in GMR sensor. This paper focuses on a method of disconnection detection with the GMR sensor at under the bonding wire and selecting the appropriate GMR sensor position.

Design challenges for 13.56MHz 10 kW resonant inverter for wireless power transfer systems

Nguyen Kien Trung,Kan Akatsu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents the design process of a 13.56 MHz 10 kW and high efficiency inverter for wireless power transfer systems. The main challenges that are the effect of the parasitic components, the using of the high-speed switching devices and the inverter topology are discussed. Finally, an optimal design of 10kW inverter using E-mode GaN is shown with the efficiency of over 95%.

The Study on Position Sensor Fault Detection and Algorithm Transition from Sensored to Sensorless Control for IPMSM

Dongwoo Lee,Kan Akatsu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents a study on the algorithm transition from sensored to sensorless control when the position sensor fault of interior permanent magnet synchronous motor (IPMSM) occurs. The determination of threshold values related to the difference between estimated value and actual value is necessary to decide the fault condition of speed and position sensor. This threshold value should be selected by a higher value than the maximum overshoot caused by acceleration or deceleration of motor as well as steady state error. The overshoot values are depend on the gain of speed and position estimator for sensorless control. In this paper, the relation between the overshoot values and estimator gains is studied to define the stable selection of threshold value. The designed estimator gain and threshold value are verified by experimental results in order to obtain the stable algorithm transition.

Variable characteristics DC motor by changing brush lead angle to expand the operation range

Daichi Takura,Kan Akatsu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposes a variable characteristics DC motor by changing a brush lead angle to expand the motor operation range. In the proposed method, to change the brushes angle of DC motor means to change the current phase flowing into a motor. By using this technique, the back-EMF can be variable, the motor driving range can be expanded. The definition of brush lead angle in this study is firstly explained. Next, it is shown that the brush lead angle is considered as a same meaning with a current lead angle of Permanent Magnet Synchronous Motors (PMSMs) by adapting dq theory to the DC motor. Adding that, a simulation result that the brush angle of DC motor determines the operation range is shown and effectiveness of the proposed method is verified by experiments. Finally it clarifies the drive range expansion with efficiency in each brush angle.

Vibration Reduction Method in SRM with a Smoothing Voltage Commutation by PWM

Akiko Tanabe,Kan Akatsu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Vibration and acoustic noise generated by the excitation force at radial direction (radial force) of Switched Reluctance Motors are the most critical issue. Due to these unfavorable characteristics of SR motors, the application for the industry machine has been delayed. The main factor of the vibration in the driving condition is caused by an electromagnetic force in the radial direction. The radial force is generated when the voltage instantly turned off, this instantaneous voltage change makes all of resonant frequency of the motor excite. This paper considers that a relationship between a variation of the input voltage and the generated vibration to establish a low vibration and low acoustic noise driving method. A new method to reduce them by adding a smoothing voltage modulated by PWM is proposed in this paper, the method is compared with the conventional single pulse operation by experimental results.

Observation of ^B+→^K+ηγ

Nishida, S.,Abe, K.,Aihara, H.,Akatsu, M.,Asano, Y.,Aulchenko, V.,Aushev, T.,Bahinipati, S.,Bakich, A.M.,Ban, Y.,Banerjee, S.,Bedny, I.,Bitenc, U.,Bizjak, I.,Blyth, S.,Bondar, A.,Bozek, A.,Brač,k Elsevier 2005 Physics letters: B Vol.610 No.1

<P><B>Abstract</B></P><P>We report measurements of radiative <I>B</I> decays with Kηγ final states, using a data sample of 253 <SUP>fb−1</SUP> recorded at the ϒ(4S) resonance with the Belle detector at the KEKB <SUP>e+</SUP><SUP>e−</SUP> storage ring. We observe <SUP>B+</SUP>→<SUP>K+</SUP>ηγ for the first time with a branching fraction of (8.4±1.5(stat)−0.9+1.2(syst))×<SUP>10−6</SUP> for <SUB>MKη</SUB><2.4 GeV/<SUP>c2</SUP>, and find evidence of <SUP>B0</SUP>→<SUP>K0</SUP>ηγ. We also search for B→K3∗(1780)γ.</P>