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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
;
Jaiwanglok, Anurak
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Julsereewong, Amphawan
;
Asadi, Farzin
;
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
;
Do, Wanglok
;
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
;
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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Design of a nesting-type switched-capacitor AC/DC converter using voltage equalizers
(2017-01-01)
Eguchi, Kei
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Junsing, Tipparat
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Julsereewong, Amphawan
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Do, Wanglok
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Oota, Ichirou
For electric appliances, an electric circuit that changes an alternating current (ac) into a direct current (dc) is necessary. Among others, a small and light ac/dc converter is indispensable to develop novel mobile devices. As one of the most promising design approaches, the ac/dc converter designed by switched-capacitor (SC) techniques attracts many researchers’ attention, because the SC ac/dc converter can be implemented without a high turn ratio transformer. Owing to the heavy transformer-less design, the SC ac/dc converter can realize smaller size and lighter weight than traditional ac/dc con-verters. However, the SC ac/dc converter suffers from complexity of the circuit control and the inflexibility of conversion ratio. To overcome these problems, this paper proposes a nesting-type SC ac/dc converter using voltage equalizers. Unlike conventional SC ac/dc converters, the proposed converter consists of a full waveform rectifier with a big capaci-tor and nested voltage equalizers. In the nested voltage equalizers, a part of the capacitor voltage of a voltage equalizer is converted by other voltage equalizers, where each voltage equalizer is controlled by non-overlapped two-phase clock pulses. By the nesting conver-sion, the conversion ratio of the proposed converter is expressed as a reverse value of the total sum of main capacitors’ voltage ratios. Therefore, the proposed converter can achieve not only simple circuit control but also flexible conversion ratios. Concerning the 1/9× step-down SC ac/dc converter, the advantages of the proposed converter were investigated by theoretical analysis, simulated program with integrated circuit emphasis (SPICE) simulations, and experiments. First, mathematical formulas for estimating the characteristics of the proposed converter were derived theoretically by utilizing a simple four equivalent circuit. Then, by comparing the proposed converter with conventional SC ac/dc converters, the effectiveness of the proposed converter was clarified by SPICE simulations. Finally, the feasibility of the proposed converter was confirmed by using the experimental circuit implemented on a breadboard.
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Parallel-connected high voltage multiplier with symmetrical structure
(2014-01-01)
Eguchi, Kei
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Pongswatd, Sawai
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Terada, Shinya
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Oota, Ichirou
A high voltage multiplier is proposed for non-thermal food processing systems utilizing an underwater shockwave. Unlike conventional Cockcroft-Walton Voltage Multiplier (CWVM) providing a DC output from an AC input, the proposed multiplier consists of two switched-capacitorbased DC-DC converters with different polarities. Owing to the symmetrical bipolar structure without magnetic component, the proposed multiplier can achieve faster response speed and lower voltage drop than the conventional CWVM. The theoretical analysis and simulation program with integrated circuit emphasis (SPICE) simulations show the effectiveness of the proposed voltage multiplier. © (2014) Trans Tech Publications, Switzerland.
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Design of a dual-input buck-boost converter for mobile back-lighting applications
(2012-04-01)
Eguchi, Kei
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Pongswatd, Sawai
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Julsereewong, Amphawan
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Oota, Ichirou
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Terada, Shinya
For mobile back-lighting applications, a dual-input white LED (WLED) driver using a bi-direction buck-boost converter is proposed in this paper. The proposed driver has two input terminals: battery input V <inf>in1</inf> and solar-cell input V <inf>in2</inf>. Unlike conventional drivers using boost converters, step-up SC DC-DC converters, and so on, the proposed converter drives the anode and the cathode of LEDs by using the solar-cell's voltage and the negative stepped-down voltage, respectively. Furthermore, by converting solar energy, the proposed driver can charge a rechargeable battery when the LED backlight is standby mode. Therefore, the proposed driver can achieve long battery lifetime. The validity of the proposed driver is confirmed by SPICE simulations and experiments. SPICE simulations show that the proposed driver can offer the sufficient voltage to drive LEDs by using solar energy and battery energy in spite of the variation in V <inf>in2</inf>. Furthermore, by employing a bi-direction buck-boost converter, the proposed driver provides us to realize long battery lifetime, because the battery charge process was confirmed by experiments. © 2012 ICIC International.
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A switched-capacitor-based serial DC-DC converter using clean energy power supplies
(2011-06-01)
Eguchi, Kei
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Pongswatd, Sawai
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Tirasesth, Kitti
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Sasaki, Hirofumi
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Oota, Ichirou
Aimed at mobile back-lighting applications, a switched-capacitor-based serial DC-DC converter is proposed in this paper. By using battery energy and solar energy, the proposed converter generates the stepped-up voltage to drive white LEDs. Unlike conventional multiple-input parallel converters, the output voltage of the proposed converter is generated by adding the output voltage of the SC-based circuit to the voltage of solar-cells. For this reason, the proposed converter can realize not only small hardware-cost but also wide input-range. Concretely, in comparison with the conventional parallel converter using 1.5 × step-up SC converters, the proposed converter can achieve 20% reduction of hardware cost and 16% extension of input range. The characteristics of the proposed converter are clarified by theoretical analyses. Furthermore, SPICE simulations and experiments show the validity of circuit design, where theoretical results correspond well with simulation results. For this reason, derived theoretical formulas can provide basic information to design serial SC DC-DC converters. The proposed converter will be useful as a LED driver circuit for display back-lighting. © 2011 ICIC International.
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Synthesis and analysis of a dual-input parallel DC-DC converter designed by using switched capacitor techniques
(2011-04-01)
Eguchi, Kei
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Oota, Ichirou
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Pongswatd, Sawai
;
Julsereewong, Amphawan
;
Tirasesth, Kitti
As a building block of mobile equipments, single-input switched-capacitor (SC) power converters have been used. However, the single-input converter is difficult to improve battery runtime by adjusting a voltage conversion ratio, because the ratio of the voltage conversion is predetermined by circuit structure. To solve this problem, a dual-input parallel-connected converter designed by the SC technique is proposed in this paper. Although the conventional single-input converter uses a lithium battery as an input energy source, the proposed dual-input converter uses not only a lithium battery but also solar cells. For the conventional SC converters, the energy conversion of clean energy is difficult, because the voltage of clean energy sources such as solar cells is sensitive to weather condition. To adopt the change in the voltage of clean energy input, the proposed converter provides the multi-state step-up conversion. By converting clean energy, the proposed converter realizes long battery runtime. Moreover, to design the multiple-input converter, the theoretical analysis to clarify circuit characteristics is required, because detailed analyses concerning multiple-input SC DC-DC converters have not been performed yet. Therefore, concerning circuit characteristics of the proposed dual-input converter, handy theoretical formulas are given in this paper. Through SPICE simulations, theoretical analyses and experiments, the validity of the proposed converter is confirmed. The theoretical results correspond well with SPICE simulation results. Therefore, the proposed analysis technique can be extended to the circuit design of other multiple-input SC DC-DC converters. Furthermore, the experimental results show that the proposed converter can generate the stepped-up voltage in spite of the change in the voltage of solar cells. Therefore, the proposed converter can realize long battery runtime. ICIC International © 2011.

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