A closed-loop power controller model of series-resonant-inverter-fitted induction heating system

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1 ACHIES OF EECTICA ENGINEEING O. 654, pp DOI 0.55/ee A cloed-loop power controller model of erie-reonnt-inverter-fitted induction heting ytem AASH A, DEBABATA OY, AIK DATTA, ADI K. SADHU 3, ATANU BANEJEE 4 Deprtment of Electricl Engineering Sroj Mohn Intitute of Technology, Degree Engineering Diviion Guptipr, Hooghly-75, Wet Bengl, Indi Deprtment of Electricl Engineering Btngr Intitute of Engineering, Mngement & Science, A unit of Techno Indi Group B7-360 / New,Wrd No. 30, utkhli, Mhehtl, Kolkt-7004,Wet Bengl, Indi 3 Deprtment of Electricl Engineering Indin Intitute of Technology, Indin School of Mine, Dhnbd Under Mhrd, Govt. Of Indi Dhnbd-86004, Jhrkhnd, Indi 4 Deprtment of Electricl Eng. Ntionl Intitute of Technology, Meghly An Intitute of Ntionl Importnce under MHD, Govt. of Indi Bijni Complex, itumkhrh, Shillong Meghly, Indi e-mil : debbrtroy985@gmil.com eceived: , revied: Abtrct: Thi pper preent mthemticl model of power controller for high-frequency induction heting ytem bed on modified hlf-bridge erie reonnt inverter. The output rel power i precie over the heting coil, nd thi rel power i proceed feedbck ignl tht contend cloed-loop topology with proportionl-integrl-derivtive controller. Thi technique enble both control of the cloed-loop power nd determintion of the tbility of the high-frequency inverter. Unlike the topologie of exiting power controller, the propoed topology enble direct control of the rel power of the high-frequency inverter. Key word: induction heting, power controller, ID, erie reonnt inverter, MATAB. Introduction In high-frequency induction heting proce, the object being heted re iolted from the het ource. An induction heter i ued high-frequency electricl device for heting electriclly conductive mteril. A power electronic inverter circuit i incorported in the de- Downlod Dte 7//8 8:3 AM

2 88. l, D. oy, A. Dtt,.K. Sdhu, A. Bnerjee Arch. Elect. Eng. vice for generting high-frequency electricity. Becue the heting proce i contctle, high-frequency induction heting doe not hve ny dvere effect on the mteril being heted. The induction heter i precie, environment friendly, energy efficient, nd controllble; moreover, it enble rpid heting nd cn be repetedly ued. In prticulr, the het i generted within the mteril being heted, reulting in negligible het lo. By contrt, in other heting method, het i trnferred from the het ource to the mteril being heted. Accordingly, high-frequency induction heting h unique indutril, dometic, nd medicl ppliction [-3], nd it i ued in wide rnge of field. Currently, opertion uch induction bonding, brzing, welding, forging, melting, nd hrdening cn be chieved through high-frequency induction heting. Thi technique lo crete the ltet prdigm for biomedicl electronic, nd it cn be employed for blood reheting during open hert urgery [4]. The ue of high-frequency induction heting equipment i likely to incree rpidly in the ner future [5]. The high-frequency induction heting equipment require ltet regultion nd recommendtion for future development. Moreover, innovtive prcticl pproche hould be developed for improving the qulity of the input power upply of the induction heting equipment. High-frequency witching ditort the grid voltge, reulting in poor power qulity [6]. The inverter h problem when it i in permnent reonnt tte: ince it i quite ey to incree the preure in the component towrd the turtion vlue, the inverter cn be dmged. It i necery to introduce control circuit to overcome thi undeirble itution. Such control circuit cn control the repone of the inverter when the inverter i contntly operted in permnent reonnt tte [8 0]. In high-frequency inverter in permnent reonnt tte pecific technique i commonly ued for controlling the voltge nd current upply with the deired ignl error. However, the technique, which i hown in Fig., h ome demerit becue it involve lrge number of power emiconductor, driver prmeter, nd n extr control loop. Fig.. Modified high-frequency hlf-bridge erie reonnt inverter with regimented DC upply The ytem cn be controlled uing elf-dptive loop nd mut hve n operting frequency lightly greter thn the reonnt frequency of the tnk circuit, which comprie n induction-coil-heted piece in erie with reonnt cpcitor. The high-frequency induction heting inductor current cn be controlled by djuting either the output current or output Downlod Dte 7//8 8:3 AM

3 ol A cloed-loop power controller model of induction heting ytem 89 voltge of the inverter, nd the high-frequency control loop i ufficient to control thee two output prmeter [-6]. A proportionl-integrl-derivtive ID controller cn give fvourble reult in induction heting ppliction. After deigning ID controller nd correponding incorporting ID controller in high-frequency ppliction it i een tht thi controller will be more uitble in high-frequency domin. The rted feedbck cn be obtined becue the forwrd pth gin re djutble for the mot uitble reult of tbility nlyi.. High-frequency induction heting ytem The high-frequency induction heting proce conit of two mjor tge. Firt diode bridge rectifier rectifie the AC upply ignl, nd ubequently, the rectified output i fed to high-frequency inverter. An lternting mgnetic field i produced by the high-frequency current t the inverter output, reulting in n eddy current being induced. Thi eddy current i reponible for generting het t the urfce of the object being heted. The internl reitnce of the object i vitl prmeter it ply role in het genertion through Joule heting [7, 8]. A block digrm of modified DC-link high-frequency hlf-bridge erie reonnt inverter i hown in Fig.. Fig.. Block digrm of the modified DC-link high-frequency hlf-bridge current ource inverter Generlly, high-frequency induction heting involve n lternting mgnetic field nd the kin effect. The production of high-frequency lternting mgnetic field in the working coil generte het nd convert electricl energy to het energy, which i intended t the kin depth AC reitnce i decreed [7]. 3. ropoed modified hlf-bridge erie reonnt inverter The modified hlf-bridge inverter circuit i normlly deigned for providing moderte output power. Fig. 3 depict the circuit digrm of the propoed modified hlf-bridge erie reonnt inverter. Two power emiconductor witche, uch MOSFET, re ued to trigger. Antiprllel diode re connected to the witch tht llow current to flow when the min witch i turned OFF; the current flow reult from the dichrge of the inductor. If the inductor doe not dichrge, then it will not operte properly. The modified hlf-bridge erie reonnt inverter conit of two MOSFET, lod reitnce, nd lod inductnce ; Downlod Dte 7//8 8:3 AM

4 830. l, D. oy, A. Dtt,.K. Sdhu, A. Bnerjee Arch. Elect. Eng. i the working coil ued for high-frequency heting. A high power output cn be chieved t high witching frequency. N ow Temperture High Temperture C S D i T C G G S D S G Fig. 3. Induction heting ytem bed on the propoed modified hlf-bridge erie reonnt inverter Tble. Switching tble of MOSFET S S out ON OFF i / OFF ON i / Tble how the witching opertion of MOSFET. In thi tudy, MOSFET were ued olid tte witche becue they re uitble for high-frequency opertion. In Fig. 3, ntiprllel diode D nd D, which re connected to the witche S nd S repectively, llow current to flow when the min witch i turned OFF. When there i no ignl t S nd S, cpcitor C nd C re chrged uch tht ech of the cpcitor h voltge of i /. A gte pule pper t the gte G nd turn S ON. Cpcitor C dichrge through the pth NOTN, nd imultneouly, cpcitor C chrge through the pth NOTS. Fig. 4 how the direction of current flow through n induction heting ytem bed on the modified hlfbridge erie reonnt inverter, when S i turned ON. When S i turned OFF, the inductor trt dichrging through the pth TS. Fig. 5 how the dichrging pth. Furthermore, the dichrging current of C nd the chrging current of C imultneouly flow from to T. N C S i T G D C S D S Fig. 4. Current flow digrm of the induction heting ytem bed on the modified hlf-bridge erie reonnt inverter, when S i turned ON G Downlod Dte 7//8 8:3 AM

5 ol A cloed-loop power controller model of induction heting ytem 83 N i T C S G D C S D S G Fig. 5. Dichrging pth of the inductor when S i turned OFF In the next lit of the gte pule, S nd S re in the OFF tte, nd ech of the cpcitor i gin chrged to voltge of i/. A gte pule pper t the gte G to turn ON the witch S. Furthermore, the cpcitor C dichrge through the pth TST, nd the chrging pth for cpcitor C i NTS. The dichrging current of C nd the chrging current of C imultneouly flow from T to. Fig. 6 depict the current flow digrm of the heting ytem bed on the modified hlf-bridge erie reonnt inverter, when S i turned OFF, nd Fig. 7 how the dichrging pth of the inductor when S i turned OFF. N i T C G S D C S D G S Fig. 6. Current flow digrm of the heting ytem bed on the modified hlf-bridge erie reonnt inverter, when S i turned OFF N i T C G S D C S D G S Fig. 7. Dichrging pth of the inductor when S i turned OFF To prevent the voltge ource from being hort-circuited, the witche S nd S mut not operte imultneouly. For reitive lod, the current nd voltge wveform re in phe, unlike the ce of rective lod. Two freewheeling diode offer dichrging pth for the energied inductor. Fig. 8 depict the output voltge wveform of the modified hlf-bridge erie reonnt inverter. Downlod Dte 7//8 8:3 AM

6 83. l, D. oy, A. Dtt,.K. Sdhu, A. Bnerjee Arch. Elect. Eng. Fig. 8. Output voltge wveform of the modified hlf-bridge erie reonnt inverter Sufficient het i produced by the eddy current t high frequencie to the working coil. eonnce occur when the inductor nd cpcitor exchnge energy. The reonting component nd witching device of the modified hlf-bridge inverter re connected in erie with the lod for reliing n underdmped circuit. Owing to the nturl chrcteritic of the underdmped circuit, the current through the witching device i zero. In voltge ource inverter, two witche of n inverter leg cnnot be turned on imultneouly ince it cn cue hort circuit. The time intervl between the turning off of witch nd the turning on of the other witch i clled ded time. In thi methodology, ntiprllel diode re ued in the induction heting ytem to fcilitte freewheeling opertion for llowing the inductor to dichrge when one of the witche i in the OFF tte. 4. Decription of block digrm of propoed cloed-loop induction heting ytem Fig. 9. Block digrm of the propoed cloed-loop induction heting ytem Figure 9 preent block digrm of the propoed cloed-loop induction heting ytem with ID controller. The ID controller output i directly provided to the comprtor. The comprtor output i 0 when the ID controller output i greter leer thn 0. The comprtor output i recorded by the flip-flop. Furthermore, the flip-flop output i connected to lod with zero-croing current tht oberved the ytem in permnent reonnt tte. The enor provide feedbck ignl to the input, nd the power error cn be nlyed. The mot ignificnt block re the enor, ID controller, nd lod circuit, nd the other block likely contnt block cn be incorported in the totl ytem repone. The overll trnfer function cn be obtined from the block digrm of the propoed cloed-loop induction heting ytem, nd the overll ytem repone for high-frequency induction heting cn be determined. Owing to the ddition of the ID controller, the inverter Downlod Dte 7//8 8:3 AM

7 ol A cloed-loop power controller model of induction heting ytem 833 repone will be very ft, nd the inverter cn be operted in permnent reonnt tte without ny problem. The definition of the vrible nd the ignificnce of the block in Fig. 9 re follow: ref i the reference power, e i the difference between the output power nd the input power i.e., error in the power, f i the power of the feedbck ignl, o i the output power, the ID block i compentor network, the comprtor nd flip-flop block re ynchronou delt genertor, nd the enor block i rel power meurement ytem; the erie reonnt inverter SI i lo referred to power tge model nd comprie power witch, lod circuit, nd power upply. Figure 0 how the ID compentor circuit digrm with the clic nlogue topology. The circuit cn be mthemticlly expreed Fig. 0. ID compentor circuit digrm C o f i f C C Thi ytem cn be tuned by chnging the prmeter.. Fig.. Block digrm of the power enor Fig. how block digrm of the power enor. The power eqution i given by nd the output of the low-p filter i given by out I out int φ out I out in φ Downlod Dte 7//8 8:3 AM

8 834. l, D. oy, A. Dtt,.K. Sdhu, A. Bnerjee Arch. Elect. Eng. outiout outiout in φ φ. The overll trnfer function of the power enor cn be obtined fter the filter i deigned, nd it i given by enor x y z, 4 3 b c d e where x, y, z,, b, c, d, nd e re the coefficient of the order of the trnfer function. For high-power witche, n ctivtor i required. The flip-flop i type of ctivtor whoe output cn be ued for mnging the driver nd ctivting the high-power witche. The flipflop doe not influence the hpe of the trnfer function, nd it i ued to develop the tructure of the cloed-loop controller only for regulting the output power. 5. od circuit model In thi context, Fig. preent the equivlent circuit of the induction heting ytem; denote the coil elf-inductnce, i the lod elf-inductnce, K i the mutul inductnce between the lod nd the coil, i the lod reitnce, i nd o re the ytem voltge, nd I nd I re the ytem current. Fig.. Equivlent circuit of the induction heting ytem Fig. 3. educed equivlent circuit of the induction heting ytem Figure 3 depict reduced equivlent circuit of the working coil nd lod ytem of the induction heting ytem. In the figure, i the primry coil elf-reitnce, i the primry Downlod Dte 7//8 8:3 AM

9 ol A cloed-loop power controller model of induction heting ytem 835 coil elf-inductnce, i the vlue of the ondry reitnce refer to the primry ide, i the vlue of the ondry inductnce refer to primry ide. The mthemticl expreion for the reduced equivlent circuit cn be derived follow by uing Fig. 9: o i j, I jki jki. ji On the bi of, I cn be written function of I : where. I Uing the vlue of I in give Therefore, the impednce i I jk I, 3 j jk j I j K I j, j K i j I. 4 j Z I cn be obtined from the primry ide, nd it i equivlent to ingle non-coupled inductor ccded with nother inductor. In prticulr, the bove expreion cn be written Z j K j K K j j j 3 j K K. 3 j K 5 Thi expreion h two prt: rel prt nd n imginry prt. The rel prt of the impednce repreent the lod reitnce reflected by the primry ide of the min coil, nd the imginry prt reduce the totl circuit inductnce. Since the rective current component i nullified in reonnt condition, reonnt cpcitor C i included in Fig. 4. Downlod Dte 7//8 8:3 AM

10 . l, D. oy, A. Dtt,.K. Sdhu, A. Bnerjee Arch. Elect. Eng. 836 Fig. 4. educed equivlent circuit digrm of the induction heting ytem The overll trnfer function i given by j j, 6 where C j nd. Agin nd. A the ytem operte under reonnt condition, the voltge i required on the primry ide, nd the voltge i identicl to t in. The invere plce trnform of 6 cn be written t e t e t t t i in co 4. 7 The power diipted in the lod upon the ppliction of tep voltge i ut i given by M M M M M i , 8 where., 4, M M The finl power trnfer function of induction heting cn be expreed Downlod Dte 7//8 8:3 AM

11 ol A cloed-loop power controller model of induction heting ytem 837 i M M 3 4M M M Simultion reult nd dicuion For the propoed topology, ll the required trnfer function were determined. The openloop ytem behviour llow chnge in the poition of pole nd zero in the ID compention network until tble configurtion i ttined. Fig. 5 depict the root locu digrm of the modified hlf-bridge SI without ID controller. Furthermore, Fig. 6 preent the openloop pole-zero digrm well the Bode plot for the me SI, howing tht the SI i untble. oot ocu Mgnitude db Img Axi he deg el Axi Fig. 5. oot locu digrm of the modified hlf-bridge SI without ID controller After ID controller i incorported, the ytem cn be eily nd directly tuned by vrying the ID prmeter. The cloed-loop behviour of the ytem with the ID controller i hown in Fig. 7. Furthermore, Fig. 8 how the cloed-loop Bode plot digrm of the ytem, reveling tble loop. In Fig. 5, mot of the open-loop pole re ituted on the right-hnd ide of the -plne, indicting tht the ytem i untble. However, fter the ID controller w incorported, becue of the decree in the ytem gin, ll the pole hifted to the left-hnd ide of the -plne Fig. 7, reflecting tble ytem. Fig. 6 depict the open-loop Bode plot digrm of the modified hlf-bridge SI without ID controller. The gin mrgin i!7.6 db, nd the phe mrgin i!90.7. Downlod Dte 7//8 8:3 AM

12 838. l, D. oy, A. Dtt,.K. Sdhu, A. Bnerjee Arch. Elect. Eng. Open-oop Bode Frequency rd/ Fig. 6. Open-loop Bode plot digrm of the modified hlf-bridge SI without ID controller oot ocu Mgnitude db Img Axi he deg el Axi Fig. 7. oot locu digrm of modified hlf-bridge SI incorporting ID controller Downlod Dte 7//8 8:3 AM

13 ol A cloed-loop power controller model of induction heting ytem 839 By contrt, Fig. 8 preent the cloed-loop Bode plot digrm of the modified hlfbridge SI incorporting ID controller; the gin mrgin i. db nd the phe mrgin i 55.. Fig. 6 nd 8 how different gin mrgin. The gin mrgin nd phe mrgin in Fig. 6 re negtive, where thoe in Fig. 8 re poitive. Generlly, poitive vlue of the gin mrgin nd phe mrgin indicte the fety mrgin for tble ytem, nd negtive vlue for n open-loop ytem indicte n untble ytem. In Fig. 6, the phe croover frequency i le thn the gin croover frequency, implying tht the open-loop ytem i untble. By contrt, in Fig. 8, the phe croover frequency i greter thn the gin croover frequency, which i the condition for n untble ytem. The forementioned reult demontrte tht the ddition of ID controller criticlly influence the tbility of the modified hlf-bridge SI, nd thi concept cn be ued in ppliction of high-frequency induction heting. Open-oop Bode Frequency rd/ Fig. 8. Cloed-loop Bode plot digrm of the modified hlf-bridge SI incorporting ID controller 7. Concluion In thi pper, it i hown tht ID controller i the mot importnt component of highfrequency induction heting equipment for chieving cloed-loop power control. With the Downlod Dte 7//8 8:3 AM

14 840. l, D. oy, A. Dtt,.K. Sdhu, A. Bnerjee Arch. Elect. Eng. mll vrition of the inverter circuit, the inverter my be uncontrolled. Furthermore, on the bi of the cloed-loop ytem behviour, it cn be predicted tht without ID controller, the inverter will be untble. So in thi pper not only the cloed-loop power i controlled, here the ytem behviour my rech to tble condition. Furthermore, control model i preented for chieving cloed-loop power control in nd the tble opertion of high-frequency inverter ytem. eference [] Srngo H., Medino.A., Burdio J.M., Cl-D/DE dul mode-opertion reonnt converter for improved-efficiency dometic induction heting ytem, IEEE Trn. ower Electronic, vol. 8, no. 3, pp [] Srngo H., Gil.O., Medino A., M. Burdio J., Modultion cheme for improved opertion of n B-IGBT-bed reonnt inverter pplied to dometic induction heting, IEEE Trn. Ind. Electron., vol. 60, no. 5, pp [3] Sinh D., Sdhu.K., l N., Deign of n Induction Heting Unit Ued in Hyperthermi Tretment, Advnce in Therpeutic Engineering, CC re, Tylor & Frnci Group, pp [4] l., Sdhu.K., l N., Bhowmik., A New Het Tretment Topology for eheting of Blood Tiue fter Open Hert Surgery, Advncement of Medicl Electronic, Springer Indi, pp [5] York B., Yu W., i J.S., Hybrid-frequency modultion for WM integrted reonnt converter, IEEE Trn. ower Electronic, vol. 8, no., pp [6] Sdhu.K., N. l,. l, Snyl S., Selection of power emiconductor witche in modified hlf bridge reonnt inverter fitted induction heter in power line for le hrmonic injection, Interntionl Journl of ower Electronic nd Drive Sytem, vol. 6, no., pp [7] Sdhu.K., l N., Bhttchry A., Deign of Working Coil Uing itz Wire for Indutril Induction Heter, p mbert Acdemic ublihing, ISBN: , pp [8] Epi J.M., Nvrro A.E., Mic J. et l., Control circuit deign of the -C reonnt inverter for induction heting, ower Electronic Specilit Conference, IEEE 3t Annul, vol. 3, pp [9] Bolen B., De Brbndere K., n den Keybu J. et l., Model-bed genertion of low ditortion current in grid coupled WM-inverter uing n C output filter, IEEE Trn. ower Electronic, vol., pp [0] hm H.N., Fujit H., Ozki K., Uchid N., Etimting method of het ditribution uing 3-D reitnce mtrix for zone-control induction heting ytem, IEEE Trn. ower Electronic, vol. 7, no. 7, pp [] Mohnt D.K., Sdhu.K., Chkrbrti., Fuzzy Mrkov model for determintion of fuzzy tte probbilitie of generting unit including the effect of mintennce cheduling, IEEE Trnction on ower Sytem, vol. 0, no. 4, pp [] Nvrro D., ucí O., Brrgán.A., Artig J.I., Urriz I., Jiménez O., Synchronou FGA-bed implementtion of digitl pule width modultor, IEEE Trn. ower Electronic, vol. 7, no. 5, pp [3] Eteve., Snchi-Kilder E., Jordn J. et l., Improving the efficiency of IGBT erie reonnt inverter uing pule denity modultion, IEEE Trn. Ind. Electron., vol. 58, no. 3, pp [4] Khn I., Tpon J., De rie I., Frequency control of current-fed inverter for induction heting, Indutril Electronic, roceeding of the 000 IEEE Interntionl Sympoium, vol., pp [5] Eglon J., Cux S., Muion., Souley M., teu O., Multiphe ytem for metl dic induction heting: Modeling nd MS current control, IEEE Trn. Ind. Appl., vol. 48, no. 5, pp Downlod Dte 7//8 8:3 AM

15 ol A cloed-loop power controller model of induction heting ytem 84 [6] Sid A., Djmel B., Boudjem I., Structurl nlyi for fult detection nd ioltion uing the mtching rnk lgorithm for reidul genertion: Appliction on n indutril wter heting ytem, Journl of Control Engineering nd Applied Informtic, vol. 5, no. 03. [7] ucí O., Burdío J.M., Millán I., Acero J., uyl D., od-dptive control lgorithm of hlf-bridge erie reonnt inverter for dometic induction heting, IEEE Trn. ower Electronic, vol. 56, no. 8, pp [8] Trentin A., Znchett., Clre J., Wheeler., Automted optiml deign of input filter for direct c/c mtrix converter, IEEE Trn. Ind. Electron., vol. 59, no. 7, pp Downlod Dte 7//8 8:3 AM