A Study on the Conducted Interference of Capacitor Charging Power Supply

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1 Enegy and Powe Engineeing, 13, 5, doi:1.436/epe.13.54b16 Published Online July 13 ( A Study on the Conducted Inteeence o Capacito Chaging Powe Supply Xiao Han 1, Yinghui Gao,3, Yaohong Sun,3, Ping Yan,3 1 Univesity o Chinese Academy o Sciences, Beijing, China Institute o Electical Engineeing, Chinese Academy o Sciences, Beijing, China 3 Key Laboatoy o Powe Electonics and Electic Dive, CAS, Beijing, China [email protected], [email protected], [email protected], [email protected] Received Febuay, 13 ABSTRACT In this pape, a mathematical analysis o the EMI (Electomagnetic Inteeence) o a khz/1 kv capacito chaging powe supply in equency-domain is pesented, and a elated cicuit model consideing the tansient switching inteeence is poposed. Due to the high woking equency and the device-switching tansitions, the conducted EMI caused by the chaging cicuit which includes the hamonics o gid equency, woking equency and device-switching tansition equencies. Thus unde cetain woking situations o loads paallel powe supply, the inteeence may cause chaging ailue. To solve this poblem, a high equency tansome modeled with stay capacitances and an appoximation o the device-switching tansition is applied in the Spice-based simulation model, and a mathematical analysis in equency-domain is pesented. Keywods: Capacito Chaging Powe Supply; Electomagnetic Tansient; Distibuted Paamete Cicuits; High Fequency and High Voltage Tansome; Fequency Domain Analysis 1. Intoduction The capacito chaging powe supply (CCPS) is an impotant powe chaging means o industial and militay applications such as distibution enegy stoage in capacitos. And because inceasing the switching equency is a common manne to obtain high powe density, which means shote tansition time duing tun-on and o o semiconducto devices and leads to geate high-equency inteeence. Moeove, the compact stuctue o high powe density CCPS complicates stay paametes, which cannot be ignoed in high-equency domain. Theeoe, the conducted EMI (Electomagnetic Inteeence) in high powe density CCPS is exacebated and it oten causes chaging ailue unde cetain woking situations o loads such as paallel powe supply. Most o the pesent models o CCPS do not take into account o the tansient switching inteeence, and the stay paamete obtaining methods ae complicated [1]. Futhemoe, the mathematical analysis o EMI in equency-domain is insuicient. In this pape, analysis o the powe supply opeation pocess was conducted and atewads the equied noninea elements wee modeled, mainly consideing the stay paametes in high equency tansome and the inteeence o the tansient switching hamonics. Satisactoy simulation esults which agee with expeimental data in equency domain wee obtained. Consequently, the study o the EMI in CCPS can impove its peomance and povide guidelines o uthe powe supply design o highe powe density.. The CCPS Opeation Pocess Figue 1 shows the coniguation o the main cicuit o a seies esonant capacito chaging powe supply (CCPS), which includes a thee-phase ectiie, an invete with high switching equency, a tansome to boost voltage and a ull wave bidge ectiication which povide the chaging DC output o load. Moeove, switching loss is deceased by a seies esonant cicuit connected to the invete with zeo cuent switching-o. Figue 1. Main cicuit o a CCPS. Copyight 13 SciRes.

2 X. HAN ET AL The gid powe is conveted by the 3-phase ectiie to a DC voltage supply, and the switching equency s o IGBTs in invete should be coodinated with the esonance equency in seies cicuit as Equation (1). (1) s Duing one switching peiod, the output cuent in esonant seies cicuit lows though one set o IGBTs and coesponding anti-paallel diodes in the ist hal cycle, and then though the othe set. The esonant output cuent oscillates to zeo exactly when the next set o IGBTs switch on due to Equation (1), achieving zeo cuent switching. Atewads, the esonant output cuent chages the capacito though a high equency step-up tansome and a ull-wave ectiie. The chaging cuent wave in each esonant peiod is simila duing the chaging pocess, which means the aveage chaging cuent level emains constant. Accoding to Equation (), the incease in capacito voltage in each stage is constant, which can be seen appoximately as linea. i C du. () c c Figue. Cicuit o 3-phase ectiie ilteed by a capacito. 3. Mathematical Analysis Analyze the opeation waveom in the chaging powe supply accoding to the opeation pocess descibed beoe, emphasizing on the esonant output cuent Cicuit o 3-phase Rectiie Filteed by a Capacito The 3-phase ectiie ilteed by a capacito is shown in Figue, in which C is the equivalence o the ilte capacito and load, and L s, R o stay paametes in load. The DC output cuent i d emains continuous when RC 3, and tuns discontinuous when RC 3 [3]. The output cuent i d and output voltage ud unde dieent sets o RC ae shown in Figue The Cicuit o Invete Accoding to 3.1, the DC output voltage o 3-phase ectiie ilteed by a capacito, which supplies o invete cicuit, contains hamonics o 6 kk ( 1,,3, ), i.e. pulses at a equency o 65 Hz 3 Hz. The pulse equency o the DC supply voltage o invete is much lage than the switching equency o esonance equency, thus the DC supply voltage can be consideed as constant when analyzing the invete waveoms. Duing one esonant peiod ~ T, a set o IGBTs (Q,Q3) switches on at t, and the coesponding anti-paallel diodes(d,d3) seve as FWD ate hal cycle, as shown in Figue 4. Figue 3. Output DC cuent unde dieent conditions; Output DC voltage unde dieent conditions. Figue 4. ~T /, cuent lows in IGBTs; T /~T, cuent lows in diodes. Copyight 13 SciRes.

3 1136 X. HAN ET AL. Figue 4 can be simpliied into Figue 5, and Equations (3)-(6) ae listed accoding to Figue 5. du i C C du 3 (3) oe u 4 u1 di L (4) ir (5) U u1 u u3 u (6) 4 whee in Coe N Co C, and since the cicuit woks unde the condition o zeo cuent switching-on and -o, the esonant cuent can be deduced as Equation (7). it () Aexp( t)sin( t) (7) Equation (7) shows that the esonant output cuent is in unde-damping oscillation om ( R< L C ). Set 1 T ( 1 LC ) as the ideal esonance equency, s 1 Ts as the switching equency, R L as the damping coeicient, and d the eal esonance equency. Duing t ~ T, set the amplitude o peak point as A 1, A, which occu sepaately at t1, t( t1 t ). Dieentiate Equation (7), and Equations (8)-(9) can be deduced. t t it () A e sin( t) Ae cos( t) (8) ( 1, ) d it (9) Thus the damping coeicient can be calculated by Equation (1). A ln / T ln A1 A1 A (1) The expeimental data shows that A1 A, A 9 A, and the equivalent seies esisto o the testing powe supply is R 1.7 by applying Equation (1). 4. Modeling o the Non-linea Element Thee ae two types o non-linea elements in the CCPS unde discussion; the high-equency tansome and the semiconducto switching devices High Fequency and High Voltage Tansome The eect o stay paametes, especially stay capacitance unde high-equency woking condition, in the tansome cannot be ignoed. The two-winding tansome model shown in Figue 6 is applicable o engineeing analysis, whee L s1, R, and 1 C1 L s, R, C ae the leakage inductances, esistances and selapacitances o the pimay, seconday windings, and L, and C m Rm 1 espectively ee to the magnetic inductance, equivalent coe loss esistance and mutual capacitance between the two windings [4]. The cicuit shown in Figue 6 can be simpliied to a two-pot netwok [5-7], as shown in Figue 7. The thee paametes in Figue 7 ae elated to paametes in Figue 6 as Equations (11)-(14). C1 C1 (1 n) C1 (11) C n C n(1 n) C (1) 1 Cs C1 C (13) Ls Ls Ls 1 (14) n Unde dieent open- and shot-cicuit cicumstances, the input impedance equations ae shown in Table 1 [6]. The numeical solutions o the elated paametes o tansome in the test powe supply ae Ls 1.57, L 6mΗ, C 5nF. m s Figue 6. Equivalent cicuit o a two-winding tansome. Figue 5. ~T /, cuent lows in IGBTs;. T /~T, cuent lows in diodes. Figue 7. Simpliied two-pot netwok o a two-winding tansome. Copyight 13 SciRes.

4 X. HAN ET AL The ideal pat o tansome could be modeled utilizing linea contolled souce as illustated in Figue 8, and the whole tansome model can be obtained when combined with the stay paametes. 4.. Semiconducto Switching Devices The semiconducto elements contained in the powe supply includes powe diodes in the thee-phase ectiie, IGBTs with anti-paallel diodes in the invete and diodes in the ull wave bidge ectiication. All these semiconducto elements can be modeled by utilizing the Model Edito in Cadence Pspice accessoies, and the chaacteistic paametes o cuves can be obtained diectly om datasheet o measued. Actually all the semiconductos can be simulated with ideal model except o the anti-paallel diodes in invete, the evese ecovey pocess o which cause inteeence duing the cicuit changing peiod, as shown in Figue 9, t ~ t3. Consideing the simulation pecision and convegence, a sub-cicuit Spice model could be applied in simulating the RR pocess o anti-paallel diodes [8], as pincipally sketched in Figue 1. Figue 8. Ideal pat o the tansome. Figue 9. Expeimental cuve o output cuent in esonant seies cicuit. Figue 1. The sub-cicuit model o anti-paallel diode. The testing powe supply used FF3R1KS4 module o invete pat, and the paametes o anti-paallel diode can be obtained by its datasheet ( 15 ns, 6 ns, C 1p. The paametes o diode VD o simulating jn o- wad impedance ae IS.894, N.18, RS.1, IKF.1377e 5 ) [9]. 5. Simulation Results and Analysis 5.1. Simulation Results 5.. Fequency Domain Analysis The simulation esults agee in acceptable accuacy with the expeimental data by applying the models discussed beoe. Figue 11 shows the simulated evese cuent unde dieent sets o esonance impedance Z L C o the esonant seies cicuit, it can be speciied that when the esonance impedance deceases, the peak evese cuent and the evese ecovey time inceases, which geneally esults in lage ipple components. Deduce the equency spectum envelope by applying the Fouie dieential invaiants Equations (15)-(16), which coesponds to the db/dec and ndb/dec espectively [1]. F( ) ( t) (15) ( n ) () t F( ) (16) n Substitute Equations (15)-(16) in Equation (7), in which n 1 in Equation (16), and Equations (17)-(18) espectively o db/dec and -db/dec ae obtained, and the intesection point is the tuning equency. T T / F1 ( ) i( t) A ( e 1) (17) () t1 T i t A e T / ( ) (1 ) F e (18) Sequentially, othe tuning equency points can be calculated in this way. The cuent hamonics dastically decay at 4 khz o the testing powe supply. The evese ecovey cuent ipple can be handled as a tiangula wave whose ising time and alling time ae detemined by the diode essential eatues and the extenal paamete esonance impedance Z, as explained in 5.1. And the spectum envelope tuning equency point o the ipple is veiied by Equation (19). tuning 1 1 (19) The calculating esult o testing powe supply is.8 MHz with the utilization o expeimental data. Figue 1 shows the spectum envelope o simulated Copyight 13 SciRes.

5 1138 X. HAN ET AL. In this pape, a cicuit model consideing the tansient switching inteeence o a khz/1 kv capacito chaging powe supply is poposed, in which the stay paametes o high-equency tansome ae numeically solved and an appoximation o the device-switching tansition ae pesented. Then the cicuit model is analyzed in equency domain and compaed with the expeimental data. Atewads, uthe details can be povided o the ealization o EMI eduction in high equency and high voltage capacito chaging powe supply. Figue 11. Simulated evese cuent unde dieent sets o esonance impedance. Figue 1. The Bode diagam o output chaging cuent compaing expeimental esults and simulation esults. The two cuves agee at hamonic inteeence points in khz elated ange and supe-.8mhz ange, the ome caused by switching equency and the latte caused by tansient switching inteeence. output chaging cuent, it is in accodance at most equencies compaed with the expeimental data. 6. Conclusions REFERENCES [1] W. L. Zhang, Investigation on Switching Powe Supply with High Voltage and High Powe (M.S., Gaduate school, Chinese Academy o Sciences, Beijing, China, 3. [] D. Xing, Development o the 5 khz Capacito Chaging Powe Supply using Seies Resonant Topology (M.S., Gaduate School, Chinese Academy o Sciences, Beijing, China, 1. [3] Z. A. Wang and J. Huang, Powe Electonics, 4th Edition, China: Machine Pess,. [4] J. Bienacki and D. Czakowski, High Fequency Tansome Modeling, ISCAS 1: Sydney, Austalia, 1, pp [5] Y. A. Wang, Study o A High Powe Fequency Voltage Switch Supply and Monito System o Electostatic Pecipitato (ESP) Use, Ph.D., Shanghai Jiao Tong Univesity, China, 1. [6] H. Y. Lu, J. G. Zhu and S. Y. R. Hui, Expeimental Detemination o Stay Capacitances in High Fequency Tansomes, IEEE Tansactions. [7] Z. Y. Zhao, H. H. Qin and C. Y. Gong, Inluences and Suppession Method o Tansome Winding Capacitance in High-enquency High-voltage Flyback Convete, Advanced Technology o Electical Engineeing and Enegy, No. 4, 6, pp [8] Y. C. Liang and V. J. Gosbell, Diode Fowad and Revese Recovey Model o Powe Electonic SPICE Simulations, IEEE Tansactions on Powe Electonics, Vol. 5, No. 3, 199, pp [9] L. Z. Yao, Geneal Cicuit Simulation Technology and Sotwae Applications: Spice and Pspice, Beijing: Publishing House o Electonics Industy, [1] W. M. Ma, L. Zhang and J. Meng, Electomagnetic Compatibility o Independent Powe System and Powe Electonics Device, 1st ed., Science Pess, Beijing, 7. Copyight 13 SciRes.