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48 results on '"Obara, Hidemine"'

12. An Optimization Method of a Digital Active Gate Driver Under Continuous Switching Operation Being Capable of Suppressing Surge Voltage and Power Loss in PWM Inverters.

Author

Yamaguchi, Daiki, Cheng, Yu Shan, Mannen, Tomoyuki, Obara, Hidemine, Wada, Keiji, Sai, Toru, Takamiya, Makoto, and Sakurai, Takayasu

Subjects
PULSE width modulation, PULSE width modulation inverters, PULSE width modulation transformers, VOLTAGE, MANUFACTURING processes, LOGIC circuits
Abstract

This article proposes a new optimization method and its platform for automatically adjusting the control parameters of a digital active gate driver while operating a pulse-width modulation (PWM) inverter. The proposed optimization method applies the searching parameters for some sectors in an ac current cycle and fixed parameters for the other sectors. This enables us to find the optimal operating points of power devices so as to reduce the surge voltage and switching loss with the consideration of their dependency on the load current. Additionally, the proposed optimization method also can find the operating points while the inverter performs a continuous switching operation. For this reason, the proposed optimization method can be applied to a continuous running test of PWM inverters, for example, in a manufacturing process. The validity of the proposed method and platform was evaluated by using a 10-kW three-phase PWM inverter with digital gate drives. The experimental results confirmed that the proposed optimization method makes it possible to find the optimal operating points for reducing the surge voltage and/or the power loss. [ABSTRACT FROM AUTHOR]

Published
2022
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22. Flying-Capacitor Linear Amplifier With Capacitor Voltage Balancing for High-Efficiency and Low Distortion.

Author

Obara, Hidemine, Ohno, Tatsuki, Katayama, Masaya, and Kawamura, Atsuo

Subjects
*CAPACITORS, *METAL oxide semiconductor field-effect transistors, *VOLTAGE control, *FLY control, *LOGIC circuits, *ELECTROMAGNETIC interference
Abstract

This article presents a flying-capacitor linear amplifier (FCLA) that achieves high efficiency, low harmonic distortion, and low electromagnetic interference (EMI). A conventional class-B linear amplifier cannot be used in power conversion applications, because the power loss generated in active-state MOSFETs is high compared with the loss generated in switching operations. In the proposed FCLA, multiple series-connected MOSFETs are used, and only one MOSFET operates in the active state at a time. Thus, the power loss generated in the MOSFETs can be reduced, and the FCLA can achieve high efficiency without performing the switching operation. In this study, the features of the FCLA and conventional linear amplifiers are theoretically compared and evaluated. Moreover, a voltage balancing control for flying capacitors is proposed and verified through simulations and experiments. It is demonstrated that the prototype 12-series FCLA achieves over 89% efficiency and generates low harmonics and low EMI. The proposed configuration is useful for increasing the number of series MOSFETs, and it contributes to realizing a power converter with advantages such as low harmonic distortion, low EMI, and high efficiency. [ABSTRACT FROM AUTHOR]

Published
2021
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23. Design for nonlinear current reference deadbeat control for boost converter

Author

Mushi, Aviti, Nagai, Sakahisa, Obara, Hidemine, and Kawamura, Atsuo

Subjects
Engineering, Settling time, business.industry, 020208 electrical & electronic engineering, 02 engineering and technology, Converters, Inductor, Compensation (engineering), Nonlinear system, Control theory, Boost converter, 0202 electrical engineering, electronic engineering, information engineering, Electronic engineering, DC-DC boost converter, Digital control, Disturbance rejection, business, Voltage
Abstract

This paper describes a design for fast and robust nonlinear deadbeat control for boost DC–DC converters. Nonlinear current reference deadbeat control is derived based on nonlinear state equation of the converter. Load disturbance compensation is implemented thus forming a new robust nonlinear controller. Both experiments and simulations of boost converter with input 12 V, output 20 V, load 4 Ω and 100 kHz sampling frequency, confirmed the voltage command tracking capability 266 μs settling time, and also disturbance rejection 1.20 ms recovery time. The method is applicable to boost converters of various applications.

Published
2017

38. Application of Multi-Level Converter for Fast Current Control in Small-Scale DC Power Network.

Author

Katayama, Masaya, Ohno, Tatsuki, Obara, Hidemine, and Kawamura, Atsuo

Subjects
VOLTAGE control, MICROGRIDS, ELECTRIC controllers, ELECTRIC current converters, ELECTRIC impedance
Abstract

DC microgrids have been emerging as next-generation small-scale electric power networks, where the line impedance is very low. This phenomenon causes large currents in the microgrids, even for a slight change in voltage; therefore, it is critical for a power flow controller to have faster transient response and precise power flow control. In this study, multi-level converters are applied as the power flow controllers to realize high-speed and high-precision power flow control in a dc microgrid. The output filter can be small, as a multi-level converter is used. This paper also presents the design of the output LC filter of a multi-level converter to satisfy a requirement of current ripple. We experimentally verified that a multi-level converter with a smaller filter can realize high-speed and high-precision power flow control for low line impedance conditions compared with the conventional two-level converters. [ABSTRACT FROM AUTHOR]

Published
2019
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39. Active Gate Control in Half-Bridge Inverters Using Programmable Gate Driver ICs to Improve Both Surge Voltage and Converter Efficiency.

Author

Obara, Hidemine, Wada, Keiji, Miyazaki, Koutarou, Takamiya, Makoto, and Sakurai, Takayasu

Subjects
*ELECTRIC inverters, *ELECTRIC potential, *DIODES, *POTENTIAL energy, *ELECTRIC current converters
Abstract

The requirements for peripheral circuits of power converters are becoming more restrictive due to the enhancement of Si-based power devices and due to practical use of SiC device. In the design of modern high-speed switching converters, the stray inductances and capacitances both in the device package and in the gate drive circuit in addition to those in the main circuit of the power converter must be considered. In these situations, the gate driving technique represents the key technology for enhancement of high-speed switching ability of power devices, as there are design limitations to reduce the stray inductances and capacitances. So far, several active gate control methods have been proposed. Most conventional active gate drivers are configured using analog circuits such as transistors and diodes. Thus, it is difficult to reconfigure their control parameters to fit the stray inductances and capacitances after the implementation of power converter and gate circuits. As a solution to these problems, the authors have proposed a programmable gate driver IC, which is a digitally controlled circuit. This gate driver IC can control the gate current at 63 separate levels, operated by programmable fully digital 12-bit and clock signals. In this paper, an active gate current control based on the load current in a half-bridge inverter with two programmable gate driver ICs is demonstrated. This developed gate control is different to the general current feedback control followed the reference value. It is verified that the proposed active gate control can effectively improve the tradeoff relationship between the surge voltage and switching loss of the pulsewidth modulation half-bridge inverter circuit. [ABSTRACT FROM AUTHOR]

Published
2018
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