application of resonant converter in ozone generator

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Feb 15, 2006 - Makalah ini mengulas penggunaan elektronika daya dalam ... Kata kunci: elektronika daya, converter beresonansi, pembangkitan ozon.

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APPLICATION OF RESONANT CONVERTER IN OZONE GENERATOR MODEL Mochammad Facta1, Zainal Salam2, Zolkafle Bin Buntat3 1 Energy Conversion (Encon) Department 2 Encon and Inverter Quality Control Center (IQCC) Department 3 High Voltage and High Current Institute (IVAT) University of Technology Malaysia (UTM), Skudai – Johor Bahru Correspondence author: +60 755 35829, e-mail: [email protected] Abstrak Ozon adalah salah satu oksidan yang menguntungkan untuk digunakan di rumah tangga dan industri sebagai disinfektan dalam proses pengolahan makanan, ruang penyimpanan makanan, sebagai pengurang bau, perbaikan air tanah, dan pemurnian air minum. Metode teknis yang umum digunakan untuk menghasilkan ozon adalah dengan menggunakan tegangan tinggi dan frekuensi rendah. Metode semacam ini memiliki kelemahan berupa efisiensi energi yang rendah, peralatan yang berukuran besar dan terlalu berat . Makalah ini mengulas penggunaan elektronika daya dalam rangkaian inverter beresonansi untuk menghasilkan arus bolak-balik berfrekuensi tinggi. Rangkaian dasar resonansi RLC digunakan untuk studi awal dalam penentuan frekuensi resonansi inverter. Hasil yang diperoleh dari penggunaan rangkaian ini adalah tegangan terminal untuk awal pembangkitan ozone berhasil dicapai dengan menggunakan frekuensi resonansi. Kata kunci: elektronika daya, converter beresonansi, pembangkitan ozon

Abstract Ozone is one of the favorable oxidant to use in home appliance and industry as disinfectant for food processing, food storage, odor abatement, groundwater remediation, and drinking water purification. The common and previous technical method for generating ozone uses a high voltage and low frequency. This kind of method has disadvantage of energy efficiency, size and weight. This paper proposed the use power electronics in the inverter resonant circuit to produce alternating current with high frequency. The basic RLC resonance circuit is used for early study to determine resonance frequency for inverter. As the result, the ozone chamber terminal voltage had been achieved for initiation by using resonance frequency. Keywords: inverter, ozone generation, power electronics, resonant converter

1. INTRODUCTION Nowadays, ozone is becoming the oxidant of choice for many air and water applications. Ozone is widely used in industrial and domestic applications as the oxidant element for bleaching and disinfecting. It is also used in food processing, food storage, odor abatement, groundwater remediation, and drinking water purification. The application of ozone is a rapidly growing field in which the improvement in the ozone generation systems is a key issue. The best industrial method known today to generate ozone is the use of electric discharges. This technique has been investigated for a long time by many researches [1-4], but much progress is still to be done to increase the overall efficiency of existing reactors. A first possibility to increase the efficiency is the use of high frequency converters to supply the ozonizer, as opposed to the low frequency power supplies used traditionally [5]. High frequency converters provide lower power losses, lower size and weight and the possibility to control the amount of ozone generated [5]. The basic configuration of ozone generation is shown in Figure .1. The principle of operation of ozone generator (OG) consists to apply a high voltage between two parallel plaques with air inside, the high voltage produces the phenomenon know as silent discharge or Application of Resonant Converter in Ozone Generator……(Mochammad Facta)

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corona effect. The silent discharge produces ultraviolet radiations that break the oxygen molecule producing ozone. It is important to avoid the arc discharge to maintain the silent discharge, which is obtained adding a dielectric between the air gap and one of the electrodes [6-7,10]. HV Electrodes

Dielectric Material Ground Electrode

Figure.1 The basic configuration of ozone generation To design the power supply that feeds the ozone generator is necessary to know the model of the OG. The most used model for designers is shown in Figure 2.

(a)

(b)

(c)

Figure 2. The most used model of the OG a. Linier model of ozone generator which consist of capacitor and resistor b. Linier model of ozone generator which represent capacitance of air gap and dielectric c. Non linier model of Ozone generator Figure 2.a. is a linear model of ozone generators. This model represents the OG with only one resistor and capacitor. way they obtain this linear model is based on power analysis[6]. Figure 2.b. is also a liner model of OG, which take account the the capacitance due to the dielectric is represented by Cg and the capacitance due to the air gap is represented by Ca. Figure 2.c. represent non linier model of OG. The DC source with the bridge of diodes represents the silent discharge, where Vz is the voltage at which the silent discharge is produced. This is a non linear model, since when the applied voltage across Ca is lower than Vz, there is not silent discharge and the diodes of the bridge are not conducting. On the other hand, when voltage applied across Ca is greater than Vz then the silent discharge is presented, the diodes conduce and the applied voltage is equal to Vz and the effect of Ca disappears. Therefore, the equivalent model will depend on the applied voltage to Ca. Due to this non linear characteristic of Fig 2.c model, it is difficult to design the power supply basing on this model. [6] For low power application the using of half bridge inverter, has been well recognized as power converter and power supply. Due to his high efficiency and simple circuit this model has been used in other application such as in electronics ballast lamp [8-9]. In this paper , model 2.a. will be adopted in order to assist the design of power supply to ozone generator. Model 2.a. will be investigated using Electronics Work Bench, where the basic principle of RLC resonant circuit and the concept of capacitive load resonant to produce high voltage are investigated first. After that, the voltage-generated by inverter resonant is described.

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This paper proposed the used of simple resonant inverter fed the model 2a of ozone chamber. The result will be investigated for voltage at ozone chamber terminal and the output current shape of converter before high frequency and high voltage transformer. 2. INVESTIGATING THE CHARACTERISTIC OF OZONE MODEL IN RESONANT CIRCUIT The output of common inverter is square wave, which convert from DC source to AC. This energy will be fed into ozone chamber model 2.a, by variation of voltage and frequency. The simplification model of resonant circuit is depictured in Figure 3. To obtain high voltage the out put of inverter is fed to high voltage high frequency that is represented by inductor. The load is the model ozone chamber in Figure. 2.a. By using assumption that the value of capacitor and resistor model is 4.5pF and 200 kΩ. The measured value of capacitor and inductor is calculated using AC sweep program analysis using PSPICE to find the ultimate resonance frequency. The result is pictured in Figure 4. Based on the result on Figure 4, the resonant frequency will be in the range of 50 kHz until 125 kHz. The experimental is continued by applying the frequency in the RLC resonance circuit model. By using electronics workbench it is found the condition where the frequency applied under resonance frequency (ffo). The results of these three conditions are presented in Figure 5.

AC Source

Lp

Cp

Rp

Figure 3. Resonant circuit which represent inverter as ac source, transformer and ozone chamber

Figure 4. Frequency response for ozone chamber model-2a The results shown in Figure 5 has given the early information that during resonant frequency applied to the ozone chamber, the voltage obtained is possible to initiate the glowing discharge in ozone chamber. Application of Resonant Converter in Ozone Generator……(Mochammad Facta)

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(a)

(b)

(c)

Figure 5. The voltage wave at terminal of ozone chamber model when (a) f>fo, (b) f=fo, and (c) f>fo. 3. RESONANT INVERTER APPLICATION TO THE OZONE CHAMBER The resonant inverter circuit is represented in Figure 6. It consist of two HF MOSFET with their driver, high voltage and high frequency transformer and the ozone chamber. DC Power supply can be fed by single phase full bridge rectifier.

Figure 6. Configuration of resonant inverter fed ozone chamber In PSPICE program, the AC line could be rectified by full bridge rectifier which produce 240 Volt DC and fed into MOSFET. The switching of the four MOSFETs are driven synchronously by square wave signal. The frequency and the duty cycle of the signal can be adjusted to the resonant frequency of the capacitive ozone tubes and the peak voltage, respectively. Based on the result in part 2 the inductance of the series compensated inductor is designed together with the capacitance of the ozone tubes to have resonant frequencies between about 50 kHz and 125 kHz. The ozone tube behaves as a capacitor in parallel with a resistance during the discharge [11]. As the result, the output voltage which fed ozone chamber is represent in Figure 7, where there are three condition for frequency adjusted, under resonance, at resonance and above resonance frequency. From Figure 7 we can observe that under and above resonance frequency the voltage which occurs at terminal of ozone chamber is not contain energy enough to initiate the initial discharge.

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Figure 7. The different shape in terminal voltage of ozone chamber at (a) f>fo, (b) f=fo, and (c) f>fo.

Figure 8. The different output current from converter at (a) f>fo, (b) f=fo, and (c) f>fo. Figure 8 show that the operation under resonance frequency can produce higher current than at resonance frequency at power converter side. 4. SUMMARY The resonance inverter application to ozone chamber model has been investigated. The simplified resonant RLC circuit has given a good practice to determine the operating frequency to the ozone generation. The use of resonance inverter for power supply to ozone chamber has been discussed. The best result of resonance inverter of ozone generator will be obtained if the inverter supplies the electrical voltage in the same frequency of the load or ozone chamber. ACKNOWLEDGMENTS This early work has supported by Energy Conversion Department, Electrical Engineering Faculty, University of Technology Malaysia. REFERENCES [1]. Zolkafle bin Buntat, J E Harry & I R Smith, “Atmospheric pressure glow discharge and pulse streamer discharge for ozone generation”, The Institution of Engineering and Technology (IET), Loughborough University, 2007 [2]. Trunec D., A. Brablec, F. astný , “Experimental Study of Atmospheric Pressure Glow Discharge”, Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlárská 2, 61137 Brno, Czech Republic, Contributions to Plasma Physics, Volume 38, Issue 3 , Pages 435 - 445, Published Online: 15 Feb 2006, Copyright © 1998 WILEY-VCH Verlag GmbH & Co. KGaA [3]. Akinori Oda, Takashi Kimura, “Analysis of Discharge Properties in Atmospheric Pressure and Low Frequency O2 Barrier Discharges”, (Graduate School of Engineering, Nagoya Institute of Technology, Japan), POSTER session American

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Physical Society, Tuesday afternoon, September 28, 2004, Cork, Bunratty Conference Centre [4]. Schulz-von der Gathen V., “Atmospheric Pressure Glow Discharges for Surface Treatment: Selected Examples”, Universität Duisburg-Essen, Universitäts str. 5 45117 Essen, Germany, High-pressure, non-thermal plasmas, XXVII th ICPIG, Eindhoven, the Netherlands, 18-22 July, 2005 [5]. Alonso J. M., A. J. Calleja, J. Ribas, M. ValdésJ. Losada , Analysis and Design of a LowPower High-Voltage High-Frequency Power Supply for Ozone Generation, IEEE Transaction on Industrial Application 2001, page 2525 – 2532 [6]. Mario Ponce, Jorge Aguilar, Jaime Femandez, Erwin Beutelspacher, Jose M. Calderon, Claudia Cortes, “Linear and non linear models for ozone generators considering electrodes losses”,CENIDET Departamento de Electronica Interior internado Palmira sln, 62490 Cuernavaca, MEXICO, 35th Annual IEEE Power Electronics Specialists Conference Aachen. Germany, 2004 [7]. Emilia Gabriela Dinu, “Dielektrik behinderte Barrierenentladungen für großflächige Plasmabehandlungen”, Doctoral Thesis , Wuppertal , Bukarest, 2005 [8]. Muhammad H. Rashid, “Power Electronics Circuit, Devices and Application”, Prentice Hall of India Private Limited, New Delhi, 2004 [9]. Muhammad H. Rashid, “Power Electronics Circuit, Devices and Application”, Prentice Hall international Editions, 1993 [10]. M. M. Kuraica, B. M. Obradović,D. Manojlović,D. R. Ostojić, J. Purić, “Application of Coaxial Dielectric Barrier Discharge for Portable and Waste Management”, Faculty of Physics, PO Box 368, 11001 Belgrade, Serbia and Montenegro, Center for Science and Techn. Development, 11001 Belgrade, Serbia and Montenegro, Faculty of Chemistry, PO Box 158, 11001 Belgrade, Serbia and Montenegro [11]. M. Nisoa, D. Srinoum and P. Kerdthongmee, School of Science, “Development of High Voltage High Frequency Resonant Inverter Power Supply for Atmospheric Surface Glow Barrier Discharges”, Walailak University, Experimental Physics Research Unit, Walailak University, 222 Taiburi, Tasala,Nakhonsithammarat, 80160, Thailand, Solid State Phenomena Vol. 107 (2005) pp. 81-85 online at http://www.scientific.net, © (2005) Trans Tech Publications, Switzerland

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