This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.

IEEE TRANSACTIONS ON PLASMA SCIENCE 1

Study on the High-Voltage Solid-State Pulsed-PowerModulator for Parallel Reactor Operation

Seung-Ho Song , Hyun-Bin Jo, and Hong-Je Ryoo , Member, IEEE

Abstract— This paper describes a study on the high-voltagecompact solid-state pulsed-power modulator for parallel reactoroperation. The current capacity of the pulsed modulator hasbeen improved to drive multiple reactors in parallel. The pulsedischarge switch uses the IXYK120N120C3 (1200 V/120 A)insulated-gate bipolar transistor for a high current output. Thegate driver has been improved according to the characteristicsof the replaced switch. The output specifications of the modifiedpulsed-power modulator are a maximum output voltage of 40 kV,a maximum output current of 300 A, a pulsewidth rangingfrom 1.5 to 5 µs, a maximum repetition rate of 3 kHz, andan average power of 13 kW. The modulator has the dimensionsof 450×475×600 mm3, a maximum peak power of 12 MW, and amaximum power density of 93 kW/L. A resistive load experimentand a plasma reactor parallel drive test were performed. Fourparallel reactors were driven using one modulator. In addition,a 50% reduction in the concentration of toluene was obtainedthrough the experiment of the toluene gas treatment using onlyparallel plasma reactors.

Index Terms— Gas treatment, Marx generators, plasma reac-tor, solid-state pulsed-power modulator.

I. INTRODUCTION

RECENTLY, interest in environmental applicationshas been increasing owing to increasing pollution.

Regulation on air pollutant emission has been announced, andresearch on it has been actively conducted [1]–[12].

One of the ways to reduce the emission of volatile organiccompounds (VOCs) from air pollutants is the plasma treat-ment method. Gas treatment using a plasma reactor hasa faster reaction time and easier maintenance than thatusing a regenerative thermal oxidizer [3]–[12]. A solid-state pulsed-power modulator for driving a plasma reactorhas been designed in this paper [13]–[15]. The designedmodulator was applied for the gas treatment of a shipbuild-ing factory. Two reactors and a catalyst filter were usedto obtain the treatment results of more than 90% of theVOCs [12].

One of the disadvantages of gas treatment using a plasmareactor is the high cost of the modulator. A high current rating

Manuscript received January 7, 2019; revised April 8, 2019; acceptedMay 10, 2019. This work was supported in part by the NationalResearch Foundation of Korea (NRF), Korea government (MSIT), underGrant NRF-2017R1A2B3004855, and in part by the Human ResourcesProgram in Energy Technology of the Korea Institute of Energy TechnologyEvaluation and Planning (KETEP), Ministry of Trade, Industry and Energy,South Korea, under Grant 20184030202270. The review of this paper wasarranged by Senior Editor R. P. Joshi. (Corresponding author: Hong-Je Ryoo.)

The authors are with the Department of Energy System Engineering,Chung-Ang University, Seoul 06974, South Korea (e-mail: hjryoo@cau.ac.kr).

Color versions of one or more of the figures in this paper are availableonline at http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TPS.2019.2917189

TABLE I

SPECIFICATIONS OF THE TWO PULSED-POWER MODULATORS

is required because of the ringing of the output current at asingle reactor load. When the reactor is driven in parallel,the ringing of the current is reduced. It is possible to improvethe disadvantage of gas treatment using a plasma reactor bydriving multiple reactors using a modulator with an increasedoutput.

This paper presents a study on the high-voltage compactsolid-state pulsed-power modulator for a parallel reactor oper-ation. The pulsed-power modulator has been modified tomeet the requirements for the parallel reactor operation. Thedischarge switches were replaced by a high current capac-ity insulated-gate bipolar transistor (IGBT). The gate driverhas been modified to ensure a turn-off operation at a highcurrent output. A resistive load experiment with the parallelreactor operation was carried out. In addition, gas treatmentexperiments using the parallel reactor drive were performed.The experimental results demonstrate that the parallel reactoroperation can be effectively used in gas treatment applications.

II. PULSED-POWER MODULATOR FOR PARALLEL

REACTOR OPERATION

Earlier versions of solid-state pulsed-power modulators candrive a single plasma reactor. The specifications of a pulsed-power modulator required to drive single and parallel reactorsare summarized in Table I. A high value of the rated currentis required for the parallel operation of the reactor, and theother specifications are the same as the existing modulator.

The structure of the pulsed-power modulator for a singlereactor is presented in Fig. 1. The modulator consists of a

0093-3813 © 2019 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.

2 IEEE TRANSACTIONS ON PLASMA SCIENCE

Fig. 1. Structure of the pulsed-power modulator based on power cellconfiguration.

pulse inverter for the gate driver, a converter for charging thecapacitor, and a series power cell for pulse discharge. An LCCresonant converter, as a current source, was used to charge thecapacitor. The Marx-generator-based power cells are chargedin parallel and discharged in series. The voltage unbalance ofeach cell capacitor is regulated less than 5% using the thirdwinding of charging transformer. Considering the rated voltageof the IGBT and the ringing of the voltage across the switchat turn-off, the voltage of each power cell voltage is designedas 830 V [13]–[15]. The improvements for the increase of therated current are as follows.

A. Power CellFig. 2 shows the unit power cell circuit of the pulse

modulator. The storage capacitors (C1 and C2) of the powercell are charged through the voltage doubler rectifier(D1 and D2). Each cell consists of a capacitor, a dischargeIGBT, and a bypass diode [14]. The bypass diode (D1 or D2)provides a bypass path to prevent damage to the circuit whenthe abnormal operation of the switch or synchronization of thegate signal fails. Due to the bypass diode, the switch of themalfunctioning cell is clamped to the voltage of only the powercell capacitor.

To increase the rated current of the pulsed-power modulator,the discharge IGBT of the power cell was replaced by theIXYS 120N120C3 (1200 V/120 A). Table II presents thespecifications of the IGBT for a single reactor drive andthe IGBT for multiple reactor drives. The rated current ofthe replaced switch was increased to approximately thrice theprevious value and the parasitic capacitance was increasedcompared to the conventional switch. The characteristics ofthe replaced switch are considered in the gate driver.

B. Control LoopFig. 3 shows the pulse control inverter and the control

loop structure for driving the discharge IGBTs. The control

Fig. 2. Circuit of the used power cells.

TABLE II

SPECIFICATIONS OF THE TWO IGBTS

Fig. 3. Structure of the pulse control inverter with control loop for gatedriving.

loop structure allows the isolated power with the synchronizedsignal to be delivered to the entire gate driver using a singleloop. Each gate driver is connected in series with the controlloop through a transformer to provide an isolated signal toeach gate driver. The control inverter outputs a short bipolarpulse to prevent the saturation of each gate transformer. Thegate driver is toggled ON and OFF owing to the bipolar pulsesof the control loop.

C. Gate DriverThe gate driver of the discharge IGBT is operated as

presented in Fig. 4 by the signal input through the controlloop. Each gate driver utilizes a rectified control pulse as its

This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.

SONG et al.: STUDY ON THE HIGH-VOLTAGE SOLID-STATE PULSED-POWER MODULATOR FOR PARALLEL REACTOR OPERATION 3

Fig. 4. Output of the gate driver according to the control pulse.

Fig. 5. Asymmetrically modified control pulses according to IGBT character-istics. (a) Control pulse before replacement. (b) Control pulse with increasedtransmission power. (c) Improved control pulse to ensure turn-off.

driving power. The stored energy is subject to the width of theinput pulses.

The modified IGBT has approximately thrice the inputcapacitance compared to its predecessor. When applying thesame gate voltage, the energy required to drive the IGBT isproportional to the input capacitance. The output pulsewidthof the control inverter is increased according to the increasedgate driver power, as presented in Fig. 5(b). One of the majorconsiderations for high current discharges is the reliable turn-off operation of the gate driver. The gate driver must dischargeall parasitic capacitors of the IGBT. The off-pulsewidth of thecontrol pulse is increased as shown in Fig. 5(c) to ensure aturn-off operation.

III. EXPERIMENTAL RESULTS

The pulsed modulator prototype based on the designpresented in this paper was tested. A 40-kV/300-A pulseoutput experiment was conducted using a resistive load.The plasma reactor load tests of gas treatment applicationswere performed. In addition, gas treatment experiments wereconducted to verify the modulator’s effectiveness in the gastreatment applications.

Fig. 6. Output waveform of the modulator at the rated resistive loadedcondition.

Fig. 7. Experimental setup for the plasma reactors’ driving test.

A. Experimental Results With Resistive Load

The pulse output of the rated condition (40 kV/300 A) ofthe prototype was tested. A noninductive resistor of 143 �was used for the load. The output waveform of the modulatorat the rated condition is shown in Fig. 6. Output conditionswere an output voltage of 40 kV, a pulsewidth of 1.5 μs, anda repetition rate of 100 Hz. In the experiment, the North StarVD-100 (10 000:1), the Pearson Model 4997 (100:1), and theYokogawa DLM2024 (2.5 GS/s, 200 MHz) were used. Therising and falling times of the output pulses were measured as500 and 200 ns, respectively.

B. Experimental Results With Parallel Driving of the PlasmaReactors

Experiments were carried out on the plasma reactor withparallel operation using the pulsed-power modulator. For theexperiments, a total of four plasma reactors and 750-� pull-down resistors were used. The Tektronix P6015A (1000:1),the Pearson Model 4997 (100:1), and the Yokogawa DLM2024(2.5 GS/s, 200 MHz) were used to measure voltage andcurrent. Fig. 7 shows the configured experimental setup forthe plasma reactor driving test.

The parallel driving test of the plasma reactor wascarried out under the conditions of a 30-kV voltage,

This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.

4 IEEE TRANSACTIONS ON PLASMA SCIENCE

Fig. 8. Pulse current and voltage waveform for the plasma reactor paralleldriving tests with (a) single reactor, (b) two parallel reactors, (c) three parallelreactors, and (d) four parallel reactors.

a 1.5-μs pulsewidth, and a 1.5-kHz repetition rate.Fig. 8 shows the pulse current and voltage waveform forthe plasma reactor parallel driving tests. Table III shows the

TABLE III

EXPERIMENTAL RESULTS FOR PARALLEL REACTOR OPERATION

Fig. 9. Gas treatment results using pulse modulator (1 and 3: before treatmentand 2 and 4: after treatment).

experimental results for reactor parallel operation. At thebeginning of the pulse output, the current rapidly increases,and when the plasma reactor is charged, the current decreases.After the pulse output is obtained, the voltage is graduallyreduced by the pull-down resistor.

C. Experimental Results With Gas TreatmentGas treatment experiments were conducted to utilize

the pulsed-power modulator for gas treatment applications.Toluene was used as the target gas. In the experiment, onlyplasma reactors were used, without using other processingdevices such as filters or catalysts. For the test, two plasmareactors and a 3-k� pull-down resistor were used. Outputconditions were a 30-kV voltage, a 1.5- μs pulsewidth, and a1.5-kHz repetition rate, and the incoming gas velocity wasmeasured as 2 m/s. The toluene treatment experiment wasperformed twice. Fig. 9 shows the gas treatment results usingthe pulse modulator. Results 1 and 2 present the results of thefirst experiment, with 7 ppm of toluene as the input conditionand a measurement of 3.5 ppm of toluene after the treatment.Results 3 and 4 present the results of the second experiment.At the test, toluene concentration is measured as 9 ppm in theinput side and the gas flow rate of 1890 L/s is passing throughthe plasma reactor. Under this input condition, the modulatoroutput power was measured as 4.5 kW, and the toluene

This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.

SONG et al.: STUDY ON THE HIGH-VOLTAGE SOLID-STATE PULSED-POWER MODULATOR FOR PARALLEL REACTOR OPERATION 5

concentration after treatment was measured as 4.5 ppm. Thus,it is reduced by 50% at the output side and the plasma reactorefficiency was calculated as 1.89 g/kWh.

IV. CONCLUSION

This paper describes a study on the high-voltage compactsolid-state pulsed-power modulator for a parallel reactor oper-ation. The specifications required for the parallel operationwere satisfied by improving the rated current of the pulsedmodulator. The pulse discharge switch was replaced by a highcurrent capacity IGBT. The gate driver was properly modifieddepending on the replaced switch.

The implemented modulator had a size of 450 × 475 ×600 mm3, a maximum peak power of 12 MW, and a maximumpower density of 93 kW/L. A resistive load test was performedto verify the single pulse output of 40 kV/300 A. Using apulse modulator with a current capacity of 150 A, only asingle plasma reactor could be driven due to the ringing of theoutput current. The parallel operation results in a reductionof the ringing of the output current compared with that ofa single reactor drive. Four reactor drives were achievedwith a double output current rating of the modulator. As aresult, the modulator with increased rated current achievedup to four reactors without increasing the size. In addition,the gas treatment experiments have proven that the reactorparallel operation using the improved pulsed modulator canbe effectively used for environmental applications.

REFERENCES

[1] (Jan. 20, 2015). Clean Air Conservation Act Article 38-2. [Online].Available: https:/elaw.klri.re.kr/kor_service/lawView.do?lang=ENG&hseq=41386&joseq=JO0038020

[2] Korea Ministry Environ. (Dec. 2016). Hazardous Air Pollutants (HAPs)Fugitive Emission Facility Management System. [Online]. Available:https://www.keco.or.kr/en/core/prevention_haps/contentsid/3008/index.do

[3] O. Karatum and M. A. Deshusses, “A comparative study of dilute VOCstreatment in a non-thermal plasma reactor,” Chem. Eng. J., vol. 294,pp. 308–315, Jun. 2016.

[4] P. M. K. Reddy, S. Mahammadunnisa, and C. Subrahmanyam, “Catalyticnon-thermal plasma reactor for mineralization of endosulfan in aqueousmedium: A green approach for the treatment of pesticide contaminatedwater,” Chem. Eng. J., vol. 238, pp. 157–163, Feb. 2014.

[5] Q. H. Trinh, M. S. Gandhi, and Y. S. Mok, “Adsorption and plasma-catalytic oxidation of acetone over zeolite-supported silver catalyst,” Jpn.J. Appl. Phys., vol. 54, no. 1S, Nov. 2014, Art. no. 01AG04.

[6] H.-R. Paur, “Removal of volatile hydrocarbons from industrial off-gas,” in Non-Thermal Plasma Techniques for Pollution Control. Berlin,Germany: Springer, 1993, pp. 77–89.

[7] H. T. Q. An, T. P. Huu, T. Le Van, J. M. Cormier, and A. Khacef,“Application of atmospheric non thermal plasma-catalysis hybrid systemfor air pollution control: Toluene removal,” Catal. Today, vol. 176, no. 1,pp. 474–477, Nov. 2011.

[8] T. Shao et al., “A compact repetitive unipolar nanosecond-pulse gen-erator for dielectric barrier discharge application,” IEEE Trans. PlasmaSci., vol. 38, no. 7, pp. 1651–1655, Jul. 2010.

[9] H. Akiyama, S. Sakai, T. Sakugawa, and T. Namihira, “Environmentalapplications of repetitive pulsed power,” IEEE Trans. Dielectr. Electr.Insul., vol. 14, no. 4, pp. 825–833, Aug. 2007.

[10] W. Mista and R. Kacprzyk, “Decomposition of toluene using non-thermal plasma reactor at room temperature,” Catal. Today, vol. 137,nos. 2–4, pp. 345–349, Sep. 2008.

[11] K. Urashima and J.-S. Chang, “Removal of volatile organic com-pounds from air streams and industrial flue gases by non-thermalplasma technology,” IEEE Trans. Dielectr. Electr. Insul., vol. 7, no. 5,pp. 602–614, Oct. 2000.

[12] H.-S. Jin, S.-H. Song, C.-G. Cho, S.-M. Park, and H.-J. Ryoo, “Study ofexhaust air treatment from a ship building factory painting facility usingpulse plasma technology,” IEEE Trans. Plasma Sci., vol. 46, no. 10,pp. 3552–3556, Oct. 2018.

[13] S.-R. Jang, H.-J. Ryoo, G. Goussev, and G. H. Rim, “Comparative studyof MOSFET and IGBT for high repetitive pulsed power modulators,”IEEE Trans. Plasma Sci., vol. 40, no. 10, pp. 2561–2568, Oct. 2012.

[14] S.-H. Ahn, H.-J. Ryoo, J.-W. Gong, and S.-R. Jang, “Robust designof a solid-state pulsed power modulator based on modular stackingstructure,” IEEE Trans. Power Electron., vol. 30, no. 5, pp. 2570–2577,May 2015.

[15] S.-R. Jang, C.-H. Yu, and H.-J. Ryoo, “Simplified design of a solid statepulsed power modulator based on power cell structure,” IEEE Trans. Ind.Electron., vol. 65, no. 3, pp. 2112–2121, Mar. 2018.

Seung-Ho Song received the B.S. degree in electri-cal engineering from Kwangwoon University, Seoul,South Korea, in 2016. He is currently pursuing theM.S. and Ph.D. degrees with the Department ofEnergy Engineering, Chung-Ang University, Seoul.

His current research interests include soft-switchedresonant converter applications and high-voltagepulsed-power supply systems.

Hyun-Bin Jo received the B.S. degree in electronicengineering from Catholic University, Bucheon,South Korea, in 2016. He is currently pursuing theM.S. and Ph.D. degrees with the Department ofEnergy Engineering, Chung-Ang University, Seoul,South Korea.

His current research interests include high-voltagepulsed-power supply systems.

Hong-Je Ryoo (M’17) received the B.S., M.S.,and Ph.D. degrees in electrical engineering fromSungkyunkwan University, Seoul, South Korea,in 1991, 1995, and 2001, respectively.

From 1996 to 2015, he joined the Electric Propul-sion Research Division as a Principal ResearchEngineer and the Korea Electrotechnology ResearchInstitute, Changwon, South Korea, where he was aLeader with the Pulsed Power World Class Labo-ratory and the Director of the Electric PropulsionResearch Center. From 2004 to 2005, he was a Visit-

ing Scholar with WEMPEC, University of Wisconsin–Madison, Madison, WI,USA. From 2005 to 2015, he was a Professor with the Department of EnergyConversion Technology, University of Science and Technology, Daejeon,South Korea. In 2015, he joined the School of Energy Systems Engineering,Chung-Ang University, Seoul, where he is currently a Professor. His currentresearch interests include pulsed-power systems and their applications, as wellas high-power and high-voltage conversions.

Dr. Ryoo is also an Academic Director of the Korean Institute of PowerElectronics, a Senior Member of the Korean Institute of Electrical Engineers,and the Vice President of the Korean Institute of Illuminations and ElectricalInstallation Engineers.