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Family of Fibonacci-Type Marx Generators with a Single Inductor in a Three-Phase Configuration
(2024-01-01)
Eguchi, Kei
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Ishibashi, Takaaki
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Julsereewong, Amphawan
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Thepmanee, Teerawat
High-voltage discharge applications have seen a widespread adoption of solid-state Marx generators (SSMGs) in recent years. In this paper, we propose a new hybrid solid-state Marx generator (HSSMG) with a single inductor. Through the application of a three-phase Fibonacci scheme, the HSSMG is capable of achieving a substantial increase in voltage output. Furthermore, the proposed HSSMG is able to generate high voltage efficiently with fewer components. The integration of the Fibonacci and boost modules is a crucial idea in the proposed technique, where the boost module increases the output voltage of the Fibonacci module to achieve higher output voltage. Regarding the proposed two-stage HSSMG, the theoretical feasibility of the proposed topology is confirmed by theoretical analysis and Simulation Program with Integrated Circuit Emphasis (SPICE) simulations. As a result of comparative analysis, it was found that the number of circuit components of the proposed two-stage HSSMG is approximately half that of the traditional SSMG. Moreover, the newly suggested two-stage HSSMG accomplishes more than 86% power efficiency at 5 W.
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Alternative of high voltage multipliers utilizing Cockcroft–Walton multiplier blocks for 220 V and 50 Hz input
(2020-12-01)
Jaiwanglok, Anurak
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Eguchi, Kei
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Julsereewong, Amphawan
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Pannil, Pittaya
In order to be practical for converting 220 V and 50 Hz AC input into high DC output ranged between 3.5 and 4.0 kV to create underwater shockwaves in non-thermal technique for processing foods, this article presents an alternative approach for modifying conventional high voltage multipliers without magnetic elements, which are based on the use of parallel-connected Cockcroft–Walton multiplier blocks (CWMBs) in bipolar structure. The basic three-stage CWMB scheme as well as the effect of different capacitor values on its output is described. The modified high voltage multiplier with improved response speed consists of a full-wave rectifier (FWR), a two-phase driver block, a parallel-connected positive CWMB, and a parallel-connected negative CWMB. Both output voltage and power efficiency of the proposed scheme can be demonstrated by theoretical analysis results. Moreover, simulation results showing the characteristics of the proposed high voltage multiplier are also included.
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Modification of Cockcroft-Walton-based high-voltage multipliers with 220 V and 50 Hz input for non-thermal food processing apparatus
(2020-08-01)
Jaiwanglok, Anurak
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Eguchi, Kei
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Smerpitak, Krit
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Julsereewong, Amphawan
A design of high-voltage multipliers to generate underwater shockwaves is one of the most important factors for successfully providing non-thermal food processing in a cost-effective manner. To be capable of fully utilizing the Cockcroft-Walton-based high-voltage multipliers for underwater shockwave generation, this paper presents a topological modification of three interesting design approaches in bipolar structure for 220 V and 50 Hz AC input to generate more than 3.5 kV DC output within short time periods. In addition to Cockcroft-Walton multipliers (CWMs), the first modified scheme employs a positive full-wave rectifier (FWR) and positive voltage multiplier block (VMB), the second modified scheme employs positive/negative half-wave rectifiers (HWRs), and the last modified scheme employs a switched-capacitor AC-AC converter. To comparatively analyze their performances, the digitally controlled operations of the modified realization schemes as well as their electrical characteristic estimation based on a four-terminal equivalent model are described in detail. The effectiveness of three modified circuit configurations and the correctness of the given theoretical analysis are verified through SPICE (Simulation Program with Integrated Circuit Emphasis) simulation results. The formulas achieved from theoretical estimation are particularly useful when designing the proposed high-voltage multipliers (HVMs) because good agreement between the theoretical and simulation results can be achieved.
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Switched capacitor-based high voltage multiplier with 220v@50hz input for generating underwater shockwaves
(2020-01-01)
Jaiwanglok, Anurak
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Eguchi, Kei
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Julsereewong, Amphawan
Non-thermal food processing using underwater shockwaves is a cost-effective technology for preserving food items with minimal impacts on their nutritious property. In order to generate underwater shockwaves, a high voltage multiplier is the major element for system hardware implementation. To support the 220V and 50Hz AC input for generating 3.7kV DC output, this paper presents the high voltage multiplier based on switched capacitor technique. The proposed circuit consists of three main components, which are AC-DC rectifier, level shift driver, and parallel-connected voltage multiplier circuit. The theoretical relationship analysis utilizing a 4-terminal equivalent circuit is described for investigation of not only the output voltage but also the energy loss due to internal resistance and the power efficiency of the proposed high voltage multiplier. In addition, the operations of the proposed circuit are also simulated by using PSPICE program to confirm its workability.
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Modeling uncertainties in DC-DC converters with MAtLab® and PLECS®
(2018-11-07)
Asadi, Farzin
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Pongswatd, Sawai
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Eguchi, Kei
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Trung, Ngo Lam
Modeling is the process of formulating a mathematical description of the system. A model, no matter how detailed, is never a completely accurate representation of a real physical system. A mathematical model is always just an approximation of the true, physical reality of the system dynamics. Uncertainty refers to the differences or errors between model and real systems and whatever methodology is used to present these errors will be called an uncertainty model. Successful robust control-system design would depend on, to a certain extent, an appropriate description of the perturbation considered. Modeling the uncertainties in the switch mode DC-DC converters is an important step in designing robust controllers. This book studies different techniques which can be used to extract the uncertain model of DC-DC converters. Once the uncertain model is extracted, robust control techniques such as H<inf>1</inf> and µ synthesis can be used to design the robust controller. The book composed of two case studies. The first one is a buck converter and the second one is a Zeta converter. MATLAB<sup>®</sup> programming is used extensively throughout the book. Some sections use PLECS<sup>®</sup> as well. This book is intended to be guide for both academicians and practicing engineers.
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A high voltage gain SC DC-DC converter based on cross-connected fibonacci-type converter
(2018-08-13)
Eguchi, Kei
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Pongwatd, Sawai
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Asadi, Farzin
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Fujisaki, Haruka
For energy harvesting systems, this paper presents a high voltage gain switched-capacitor (SC) converter with cross-connected topology. By cross-connecting two Fibonacci-type DC-DC converters, the proposed SC DC-DC converter provides a high stepped-up voltage which is expressed as a power of two. Unlike conventional converters, the stepped-up voltage is generated in all clock phase. Furthermore, the cross-connected structure provides the reduction of internal resistance and output capacitance. Therefore, small size and efficient energy conversion can be achieved by the proposed converter. The characteristics of the proposed converter were investigated by not only SPICE simulations but also theoretical analysis, where the proposed converter demonstrated high performance such as high voltage gain, small size, high power efficiency, and fast response speed.
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Performance comparison of bit-level median filtering circuits based on binary search algorithm
(2018-06-08)
Wongjan, Anan
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Julsereewong, Amphawan
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Eguchi, Kei
Implementing bit-level median filtering circuits based on binary search algorithm is one of powerful methods to provide simple and modular configurations. The aim of this paper is to compare the performances of four median filtering circuits utilizing binary search algorithm in terms of operation time and power consumption, which are major characteristics for signal and image processing in real time. These studied filtering circuits are implemented through the employment of existing logic control and majority voting modules. Two different configurations of logic control module as well as two different configurations of majority voting module for four possible circuit realizations are described. LabVIEW simulation results are employed for verifying the performances of the studied median filtering circuits.
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Design of a non-thermal food processing system utilizing wire discharge of dual electrodes in underwater
(2018-06-01)
Eguchi, Kei
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Jaiwanglok, Anurak
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Julsereewong, Amphawan
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Asadi, Farzin
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Abe, Hiroto
To provide nutritious and fresh processed foods, non-thermal food processing technologies have been developed in recent years. Among others, a non-thermal food processing method utilizing underwater shockwaves has cost-effectiveness. In this method, the design of a high voltage multiplier and its discharging method are key factors for processing target foods effectively. This paper proposes a non-thermal food processing system utilizing wire discharge of dual electrodes in underwater. Unlike conventional non-thermal food processing systems, the proposed system has two pairs of electrodes with thin metal wires. Owing to the electric discharge using thin metal wires, the energy to generate underwater shockwaves can be decreased. For this reason, by only one electric discharge, both sides of the target food are crushed by the proposed technique. The experiments using a laboratory prototype clarified that the proposed method can soften the whole flesh of the target food effectively. Furthermore, by assuming a four-terminal model, an equivalent model of the high voltage multiplier was analyzed theoretically. Concerning the series-connected voltage multiplier, the design conditions were derived to estimate the characteristics such as output voltage and power efficiency.
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Design of a high-voltage multiplier combined with Cockcroft-Walton voltage multipliers and switched-capacitor AC-AC converters
(2017-06-01)
Eguchi, Kei
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Wongjan, Anan
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Julsereewong, Amphawan
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Do, Wanglok
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Oota, Ichirou
In recent years, the non-thermal food processing is receiving much attention, because the non-thermal food processing can offer nutritious and fresh processed foods at low cost. In the non-thermal food processing, an underwater shockwave is utilized by discharging a high voltage in water. To generate the underwater shockwave, this paper proposes a novel high voltage multiplier designed by connecting a bipolar Cockcroft- Walton voltage multiplier (CWVM) with a switched-capacitor (SC) direct ac-ac converter in series. In the proposed multiplier, first, an ac input is amplified to double by the inductor-less ac-ac converter. Then, the output of the ac-ac converter is stepped-up again by the bipolar CWVM. Therefore, owing to the inductor-less series-connected bipolar topology, the proposed multiplier can achieve smaller size and higher gain than existing multipliers. Concerning the proposed multiplier with 26 × step-up gain, the operation principle and theoretical analysis are discussed in detail. Furthermore, the feasibility and effectiveness of the proposed multiplier are demonstrated by simulation program with integrated circuit emphasis (SPICE) simulations.
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A step-down switched-capacitor AC-DC converter with double conversion topology
(2017-02-01)
Abe, Kanji
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Smerpitak, Krit
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Pongswatd, Sawai
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Oota, Ichirou
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Eguchi, Kei
In the field of portable electronic devices, a small and light AC-DC converter or AC adapter has been required in these last few decades. To meet such demands, a switched-capacitor (SC) AC-DC converter draws many researchers’ attentions in recent years. It is known that the SC AC-DC converter can realize smaller size and lighter weight than transformer-based AC-DC converters, because no magnetic component is required to design the SC AC-DC converter. In previous studies, several AC-DC converters succeeded in downsizing and light-weighting by using SC techniques. However, the power efficiency of conventional SC AC-DC converters is still low, and their control method is complicated. To overcome these problems, a step-down SC AC-DC converter with double conversion topology is proposed in this paper. The proposed converter consists of a full waveform rectifier with a big capacitor and two converter blocks. In each converter block, the 1/3 × step-down conversion is performed by connecting three capacitors in series, where electric charges stored in these capacitors are averaged by using series-connected flying capacitor. By connecting these converter blocks in series, the 1/9 × step-down conversion is realized by controlling power switches by non-overlapped two-phase clock pulses. Therefore, unlike the conventional converters using multiphase clock pulses, the proposed converter can achieve not only simple circuit control but also small ripple noise. Furthermore, the reduction of output ripple leads to the improvement of power efficiency. To help readers’ understanding for the proposed converter, first, a simple four equivalent circuit of the proposed converter is derived theoretically. The characteristics of the proposed converter are clarified by the theoretical analysis. Then, in order to demonstrate the effectiveness of the proposed converter, the proposed converter is implemented by simulated program with integrated circuit emphasis (SPICE) simulator. The validity of the theoretical results is confirmed by the SPICE simulation. Finally, the feasibility of the proposed converter is confirmed by experiments implemented on a breadboard.

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