CALCULATION OF INDUCTION DEVICE WITH SIMULATION METHODS

Transcription

1 ., 53,.I,,, 2010 ANNUAL of th Univrsity of Mining and Gology St. Ivan Rilski, Vol. 53, Part, Mchanization, lctrification and automation in mins, 2010 CALCULATION OF INDUCTION DEVICE WITH SIMULATION METHODS Goc Stfanov 1, Ljupco Karadzinov 2 Natasa Mojsoska 1 1 Univrsity Goc Dlcv, R. Macdonia, goc.stfanov@ugd.du.mk, natasa.mojsoska@ugd.du.mk 2 Univrsity Sts. Cyril and Mthodius, R. Macdonia, L.Karadzinov@ukim.du.mk ABSTRACT. In this papr is givn a procdur for practical calculation of induction dvic for mlting of th mtal with a small capacity. Usd to simulations programs ELTA, PowrSim and SmSmikron. With simulation program ELTA, for objct of invstigation work pic mtal ar dfining th paramtrs of th induction dvic. And by simulation programs PowrSim and SmSmikron th powr convrtr is optimizd. Th induction dvic is intndd for mlting 5kg coppr. 1, 2, 1 1, -mail goc.stfanov@ugd.du.mk, natasa.mojsoska@ugd.du.mk, 2,, -mail L.Karadzinov@ukim.du.mk.. ELTA, PowrSim SmSmikron. ELTA,. A PowrSim SmSmikron Introduction Th induction dvic is intndd for induction hating of mtallic matrials. Th procdur for calculating th induction dvic covr a procdur for calculating of th paramtrs of th work pic which is subjct to induction hating and procdur for optimization of th powr convrtr that will manag with induction dvic. In th papr is givn th calculations of th induction dvic for mlting of th 5kg coppr. Th procdur for calculation of th paramtr of th work pic which is subjct of th induction hating, in this papr, is basd of th simulation program. Also, th optimization of th powr convrtr that manag with th induction dvic is basd of th simulations programs. In th powr lctronic from intrst is th work of lctronic componnts as switchs. Th lctronic componnts as switchs in th lctronic circuits of powr lctronics manag by convrsion of lctrical nrgy from on to anothr shap, [1]. Major fforts for dsigning of th circuits in powr lctronics is th rducing of th pric and th siz of usd parts. High working frquncy nabls rducing of th siz of th usd inductanc L and capacitor C. So, incrasing th working frquncy allows rducing of th valus of inductanc L and capacitanc C for sam impdanc of th circuit, [4], [7]. But on th othr hand th incrasing of th working frquncy rducs th stability of powr convrtr and incrass powr switching losss, [7]. Thrfor is rquird dsigning th powr convrtrs with circuits that nabl opration of high frquncis with lss powr losss. Hr ar usd circuits that allow switching of th powr switchs at zro voltag ZVS and zro currnt ZCS. Th rsonant circuits, as output load of th powr convrtrs ar circuits that allow work on switchs with ZVS and ZCS. And bcaus of that th opration of th powr convrtr with rsonant load is of grat intrst. At working procsss with output load in th mod on induction dvic, th dynamics of procss affcts of th paramtrs of rsonant circuit. In such loads, th output powr of th convrtr not only dpnd on th ffctiv valu of voltag, but and from th frquncy. Th dynamic of work of th induction dvic affcts of th valus of inductanc L and rsistanc R of rsonant tank. Bcaus th frquncy of rsonant systm is dtrmind by L and R on th circuit, with chang of L and R of th circuit, th frquncy of rsonant tank is changing. In such mods of opration is ncssary rgulation of th output powr, [8]. 2. Calculation of th induction dvic In th dsign of th induction dvic ar usd simulation programs: Elda, [2], for dfining of th paramtrs of th induction dvic. PowrSim, [3], for modling of powr convrtr against dfind powr of th induction dvic obtaind from Elda simulation program Smsil, [6], for optimization of th powr losss of convrtr. 160

2 Dfining th working conditions: Maximum output powr (Smax): Maximum output powr of 12000VA. objct of invstigation work pic with: -cylindrical gomtry -mtal coppr -wight 5kg -maximum tmpratur is 1083ºC -tim cycl is 3600s Switching frquncy (fsw): A switching frquncy of 6 khz is usd for dsign of maximum powr. f sw 1 (1) 2 L C Typical valu for th powr factor for th induction cookr is 0.5, quation (2), [8]. FP R 2 R (2 f sw L ) Also, IGBT dvics and full bridg convrtr ar usd. A. Simulation Elda simulation programs, [2]. Induction hating is a complx combination of lctromagntic, hat transfr, and mtallurgical phnomna. Hat transfr and lctromagntic ar closly intrrlatd bcaus th physical proprtis of hat tratd matrials dpnd strongly on both magntic fild intnsity and tmpratur. In gnral, th transint (timdpndnt) hat transfr procss in a mtal work pic can b dscribd by th Fourir quation T C div( gradt ) Q (3) t whr T is th tmpratur, is th dnsity of th mtal, C is th spcific hat, is th thrmal conductivity of th mtal, and Q is th hat sourc dnsity inducd by ddy currnt s pr unit tim in a unit volum (so-calld hat gnration). In gnral cas th calculation of th paramtrs of th lctromagntic fild is basd on th calculation of Maxswll's quations for dfind mdium and gomtry. Solving of Maxswll's quations and quation for hat transfr procss in gnral and spcial cas is a complx task. Computr simulation maks th problm of dsigning th induction dvic asy and simpl. Computr simulation ar basd on numrical mthod, Finit Diffrncs Mthod and Finit Elmnt Mthod. By numrical mthods th problms of distribution of th lctromagntic fild and hat transfr in mtals is rducd for finding approximat solutions of partial diffrntial quations. In th papr is usd ELTA simulation program for stimation of th lctromagntic fild and had transfr for work pic mtal with cylindrical gomtry. In Elda simulation program toward dfind working pic of coppr th gomtry of th systm inductor, graphit crucibl, work pic is dfind: Input data (2) Work pic: Shap: Cylindr. Lngth: 15cm, finit systm lngth. Layrs: 1. Coppr, Rint=0cm, Rxt=3.75cm, T=20ºC 2. Graphit, Rint=3.75cm, Rxt=5.25m, T=20ºC Inductor: R=5.75cm Tub profil: ring, D=0.8cm, d=0.2cm, Inductor lngth: 16.5cm Numbr of turns: Rsistivity: 2 x10 cm Procssing stags: f 6kHz, U 30V Tim cycl 3600s. Magntic flux i of th inductor flows around all its turns as on stram (Fig. 1). Insid of th inductor it consists of a lakag flux s in th gap btwn th coil and work pic and flux w insid of th work pic. (4) i s w Main assumptions for Total Flux Mthod ar: 1. Magntic flux distribution insid of th coil (ara A) is th sam as in a pic of an infinitly long systm; 2. Magntic flux pattrn outsid of th coil (aras B) is approximatly th sam as for an mpty coil. Undr ths assumptions it is possibl to calculat magntic rsistancs of diffrnt parts of th systm and compos a magntic substitution circuit. In th Fig. 1 is givn quivalnt magntic circuit. Fig. 1. Equivalnt magntic circuit Magntic impdanc of th work pic Zmw may b found from analytical or numrical solution of 1D or 2D lctromagntic or coupld lctromagntic plus thrmal problm. Magntic impdanc (rluctanc) Rms of th gap may b calculatd for uniform distribution of magntic fild in th gap, which follows from assumption1. Finally, rluctanc of th back path of magntic flux (aras B, Fig. 1) may b found using Nagaoka corrction cofficint for inductanc of mpty coil. Magntic flux gnratd by th coil ampr-turns IN may b calculatd dirctly from th circuit of Fig. 1. In ELTA program for dfin work pic ar obtain tmpratur distribution and hat transfr, (3). 161

3 In th Fig. 2 is shown th tmpratur distribution for diffrnt distanc from th surfac of th work pic to its cntr. Fig. 2. Tmpratur distribution on th work pic As a paramtr appars th tim for which work pic is xposd on hating. From th diagram it is obvious that aftr t 900s tmpratur in th work pic from surfac to its cntr is 1083 º C. So aftr t 900s w can say that th mtal is mltd. In th Fig. 3 is givn tmpratur distribution of th work pic of induction furnac. Fig. 3. Tmpratur distribution of th work pic From th Fig. 3 it is obvious that aftr a tim of 900 sconds all points of work pic rach a tmpratur of 1083 ºC. Also, in Elda simulation program ar obtain wav forms of th magnituds of th systm inductor work pic. In th Fig. 4 ar prsnt th powr, th currnt, th voltag, and th impdanc of th powr convrtr. Fig. 4. Powr, currnt, voltag and impdanc In th Fig. 5 ar givn th currnt dnsity, th fficincy, th inductanc and cos for th work pic coppr. 162

4 Th capacitanc of th rsonant circuit for compnsat on th inductanc is 86 F. Th chang of th inductanc producs chang of powr of th convrtr for 13%. Whn th inductanc is minimum, th powr and th currnt hav a minimum valu and vic vrsa. Whn th rsistanc is minimum, th powr and th currnt hav a maximum valu and vic vrsa. 2 2 Z ind R I m is a modul of th impdanc of th inductor. Th chang of th powr of th convrtr shows that in such variabl loads is ncssary to build a systm for maintaining constant output powr. PowrSim simulation program. For dfind powr, currnt and frquncy on th induction dvic obtaind in Elda simulation program by th PowrSim simulation program ar dsignd powr convrtr with using simulation circuit in Fig. 6. Fig. 6. Simulating circuit in th PowrSim program Fig. 5. Currnt dnsity, fficincy, inductanc, cos In th tabl 1 ar prsnt valus of th paramtrs L, R and magnituds Iin (inductor currnt), P (powr convrtr) of th systm inductor work pic. Tabl 1 L( H) R(Zind) C( F) Iin(A) P(kW) min max Th analysis of th Fig. 3, 4, 5 and tabl 1 shows that th powr convrtr must oprat undr th following conditions: Rquird maximum powr on th convrtr is 12kW. Maximum output currnt of th convrtr is 410A. Output voltag of th convrtr is 30V. Th chang of th tmpratur of th work pic from 20 to 1083 º C producs chang on th inductanc for 2.7%. Th circuit for simulation of th Fig. 6 is tstd for th minimum (1) and maximum (2) valus of magnitudit obtaind by ELTA program, tabl 2. abl 2 tst L( H) R(Zind) C( F) (1) (2) Th rsults ar prsntd in th tabl 3. Tabl 3 IDC (A) UDC (V) PDC (kw) Uo (V) Io (A) So (kva) cos (º) (%) (1) (2) In th tabl 3 th sizs ar: 163

5 1 U o u T T 0 2 out ( t) dt is phas angl among Uo and Io P cos conv S o is fficincy on th full S o cos 100% PDC bridg convrtr SKM200GB12T4 SKM300GB066D In th Fig. 7 is givn th wav shaps of output voltag and output currnt of th convrtr. SKM400GB066D Fig. 7. Output voltag and output currnt SmSil simulation program. In th simulation program Smsil th convrtr is optimizd in trm of th switching losss, tabl 4 and th tmpratur losss, tabl 5 and Fig. 8 Tabl 4 SKM200GB12T4 SKM300GB066D SKM400GB066D Pcond tr ratd currnt ratd ratd ovrload ovrload currnt currnt ovrload 153 W 181 W 99 W 113 W 91 W 103 W Psw tr 16 W 18 W 9.8 W 11 W 8.97 W 9.98 W Ptr 169 W 199 W 109 W 124 W 100 W 113 W Pcond d 0.00 W 0.00 W 0.0 W 0.00 W Psw d 4.3 W 4.69 W 3.2W 0.00 W 0.00 W 3.41 W 3.4 W 3.64 W Pd 4.3 W 4.69 W 3.2W 3.41 W 3.4 W 3.64 W Ptot 692 W 813 W 450 W 511 W 413 W 466 W Tabl 5 SKM200GB12T4 SKM300GB066D SKM400GB066D Th 117 C 119 C 90 C 91 C 86 C 87 C Tc 130 C 134 C 99 C 101 C 94 C 96 C Ttr 154 C 162 C Td 131 C 135 C 115 C 100 C 119 C 106 C 109 C 101 C 95 C 96 C Fig. 8. Tmpratur losss for 3 diffrnt IGBT B.Analysis of rsults Th mod of th induction hating has changing dynamic which affcts of th paramtrs on th rsonant circuit, Fig. 4 and 5, and tabl 1. Th full bridg convrtr satisfis th rquirmnts for powr and currnt dfind in th tabl 1. Configuration of th full bridg convrtr with IGBT transistors SKM400GB066D has bst faturs in trm of powr losss and th tmpratur losss, tabl 4 and 5. Bcaus th mod of inductiion dvic has a variabl dynamic, th convrtr which oprats with such dvic in applications whr is rquird constant output powr must monitor and rgulat th output powr with adquat mthods of managmnt. Th frqunt and phas control ar mthods of managmnt on ths convrtrs. 3. Conclusion In th papr is prsntd mthod for calculation of induction furnac with computr simulation programs. By computr simulation solving of problms on distribution of th lctromagntic fild and th hat transfr in mtals is asy and simpl. In th papr is usd ELTA simulation program for stimation of th lctromagntic fild and th had transfr for work pic mtal with cylindrical gomtry. 164

6 For th dfind powr, currnt and frquncy on th induction dvic obtaind in ELDA simulation program by th PowrSim simulation program ar dsignd powr convrtr. By th simulation program Smsil convrtr is optimizd in trm of th switching and th tmpratur losss. Rfrncs Ericison R.W Fundamntals of Powr Elctronics, Kluwr. ELDA 4.1, 2009.Fluxcontrol, simulation program. simulation program for powr lctronic Stfanov G. Dambov R Fundmntal princips of working in rsonant convrtr for induction hating, MGU Intrnational Scintific Confrnc, Sofia, VOL.52, pp Stfanov G Computr simulation on th topologis of rsonant convrtrs usd in induction cookrs, Intrnational Scintific Confrnc "CONFERENG 2009" Tg-Jiu, Romania, ISSUE 2/2009, pp simulation program smsil for powr lctronic Viriya P. Yongyuth N. and Matsus K Analysis of Two Continuous Control Rgions of Convntional Phas Shift and Transition Phas Shift for Induction Hating Invrtr undr ZVS and NON-ZVS Opration, IEEE. Yan Y. Rgan Z. Jun Digital Phas Control for Rsonant Invrtrs, IEEE powr lctronics lttrs, VOL. 2, No. 2. Marius Orban, Maria Orban, Kuril Ianakiv, Evtim Kartzlin, Static convrtrs and thir application, St. Ivan Rilski, Publishing hous, Univrsity of mining and gology, Sofia, 2002, Rcommndd for publication of Editorial board 165