Observation and Calculation of Different Harmonics in Fly Back Converter

Transcription

1 International Journal of Recent Develoment in Engineering and Technology Webite: (ISSN (Online)) Volume 2, Iue 3, March 214) Obervation and Calculation of Different Harmonic in Fly Back Converter Pradoha Kumar Mohanty 1, R. P. Dalai 2 1 Reearch Scholar, M.Tech, CUTM, Bhubanewar 2 At Prof. Electrical Engineering CUTM, Bhubanewar Abtract-----In order to avoid dangerou interaction between ower and control art of the integrated circuit, it i neceary to control the rate of change of the ower device voltage at turn-off. Accordingly, lole aive Snubber wa added to the conventional converter toology. The Snubber alo limit the voltage ike acro the ower device, due to the tranformer leakage inductance, and reduce the electromagnetic noie generation. A baic review of the fly back witching toology will be reented with an emhai on not-o-obviou deign iue, uch a effect of araitic, fault rotection, and EMI mitigation. Modeling and analyi will be demontrated. The tudy involve analyi, circuit deign, erformance comarion and imlementation. The circuit are invetigated by mean of comuter imulation. Oerating rincile and oerating mode are tudied along with deign calculation. After alying rototye in laboratory, the imulation reult and theoretical analye are confirmed. Advantage of SMPS over linear ower uly: In linear ower uly the tranitor oerate in it active region incurring a ignificant ower lo. So efficiency i in the range of 3-6%. But in SMPS it avoid oerating in their active region o a ignificant reduction in ower loe i achieved. Thi reult in a higher energy efficiency in a 7-9% range. In linear ower uly a low frequency tranformer i required. Such tranformer are larger in ize and weight comared to high frequency tranformer. In SMPS a high frequency iolation tranformer i ued o the ize and weight of SMPS can be ignificantly reduced. II. FLY BACK CONVERTER Keyword----SMPS, MOSFET, Snubber Reitance, Snubber circuit, fly back converter I. INTRODUCTION Switch Mode Power Suly (SMPS) i the tranformation of dc voltage from one level to another i accomlihed by uing dc-to-dc converter circuit. Thee circuit emloy olid tate device (tranitor, MOSFETS, etc.) which oerate a a witch either comletely off or comletely on. Here ince the ower device are not required to oerate in their active region thi mode of oeration reult in a lower ower diiation increaed witching eed higher voltage and current rating and relatively lower cot of thee device are the factor that have contributed to the emergence of witching ower ulier. Figure:1 Thi i the circuit diagram of fly back converter. There are two mode of oeration. (i) Mode 1 when Q 1 i turned on (ii) Mode 2 when Q 2 i turned off. Different Mode of oeration MODE-I Thi mode begin when witch Q1 i turned on and it i valid for < t < KT where K i the duty cycle ratio and T i the witching eriod. 9

2 International Journal of Recent Develoment in Engineering and Technology Webite: (ISSN (Online)) Volume 2, Iue 3, March 214) The voltage acro the rimary winding of the tranformer i V. The rimary current i tart to build u and tore energy in the rimary winding. Due to ooite olarity arrangement between Inut & Outut winding of tranformer diode D 1 i revered biaed. There i no energy tranferred from the inut to load R 1. The rimary current increae linearly i given by i V L t At the end of thi mode at t = KT the eak rimary current reache a value to I (k). So i (k) i V KT (t KT) L The following waveform are the teady tate waveform under dicontinuou mode of oeration. The eak econdary current I c ( k ) i I c MODE 2 N (k) N I (k) Thi mode begin when witch Q 1 i turned off. Due to the ooite olarity diode D 1 on and charge the outut caacitor C can alo deliver current to R L. The econdary current that decreae linearly i iic (k) V Q1 V L o N (max) V (max) N V Q1 Collector voltage t The eak rimary current I ( k ) which i the ame a the maximum collector current and the rm rimary current. V I c (max) of the ower witch Q 1 i given by I (max) I c Where Pi = Inut Power 2i (k) KV Po = Outut Power = Efficiency o 2Po ηv K 91 Figure2: Waveform of Fly back Converter at dicontinuou mode of oeration III. PROTECTION SNUBBER The function of a nubber circuit i to reduce the electrical tree laced on a device during witching by a ower electronic converter to level that are within the electrical rating of the device. More exlicitly a nubber circuit reduce the witching tree to afe level by : 1. Limiting voltage alied to device during turn-off tranient. 2. Limiting device current during turn-on tranient. 3. Limiting the rate of rie of (di/dt) current through device at device turn-on. 4. Limiting the rate of rie (dv/dt) of voltage acro device during turn off. Need for nubber with Tranitor: Snubber circuit are ued to rotect the tranitor by imroving their witching trajectory, there are three baic tye of nubber. 1. Turn off nubber. 2. Turn-on nubber. 3. Over voltage nubber. Turn off Snubber: To avoid the roblem at turn-off the voltage of a turnoff nubber i to rovide a zero voltage acro the tranitor while the current turn off.

3 International Journal of Recent Develoment in Engineering and Technology Webite: (ISSN (Online)) Volume 2, Iue 3, March 214) Thi can be aroached by connecting A RCD network acro the BJT. Prior to turn off the tranitor current i Io and the tranitor voltage i eentially zero. At turn off in the reence of thi nubber the tranitor current i decreae with a contant di/dt and (I o i c ) flow into the caacitor through the nubber diode D. Therefore for a current fall time of t fi the caacitor current i i c = Iot/t n O < t < t n Figure 4: V w & I G( Gate ule) 1. The witch voltage i found to be around 2 volt 2. Due to the abent of nubber circuit the voltage ike i high u to 12 volt. Figure:3 Simulation diagram for fly back converter without nubber Figure 5: I P & I G (Gate ule)(without nubber)the rimary current i found to be 1.5 am. 92

4 International Journal of Recent Develoment in Engineering and Technology Webite: (ISSN (Online)) Volume 2, Iue 3, March 214) Figure 6: I S&I G (Gate ule)(without nubber)the econdary current i found to be.5 am. Figure 8:V Pveru I G (Gate ule)(without nubber) The rimary voltage i found to be 12 volt. The econdary voltage referred to rimary i found to be 8 volt. The ike voltage i found to be 11 volt. Figure 7: V 2 & I G (Gate ule)(with out nubber) The econdary voltage i found to be around 12volt. The rimary voltage referred to econdary i found to be 6volt Figure 9: V veru I G (Gate ule)(with out nubber)the outut voltage i found to be around 6 volt. 93

5 International Journal of Recent Develoment in Engineering and Technology Webite: (ISSN (Online)) Volume 2, Iue 3, March 214) The witch voltage i around 3 volt. An extra ike voltage of around 3 volt i develoed acro witch. By utilization of nubber circuit the ike voltage atifactory reduced. Figure 12: I &Gate ule(with nubber)the rimary current i found to be around.6 am. Figure 1: Simulation diagram for Fly back converter with nubber Figure 11: Vw & Gate-ule(with nubber) Figure 13: I 2 veru I G (Gate ule)(wth nubber)the econdary current i around 1.5 am. 94

6 Mag (% of Fundamental) International Journal of Recent Develoment in Engineering and Technology Webite: (ISSN (Online)) Volume 2, Iue 3, March 214) Figure 14: V 2 veru I G (Gate ule) The econdary voltage i found to be 18 volt. The rimary voltage referred to econdary i around 1 volt. Figure 16.: V & I G (gate current)outut voltage i found to be 12 volt. 3 IV. COMPARISON STUDY Selected ignal: cycle. FFT window (in red): 2 cycle Time () Fundamental (5Hz) = 127, THD= 8.8% Figure 15: V & I G (gate ule) (with nubber) The rimary voltage i around 2 volt, the econdary voltage referred to Primary i 1 volt. A ike of around 2 volt i develoed at rimary Figure 17.. how harmonic order of inut current.(with out nubber) 95

7 Mag (% of Fundamental) Mag (% of Fundamental) Mag (% of Fundamental) Mag (% of Fundamental) International Journal of Recent Develoment in Engineering and Technology Webite: (ISSN (Online)) Volume 2, Iue 3, March 214) 3 Selected ignal: cycle. FFT window (in red): 2 cycle 2 Selected ignal: cycle. FFT window (in red): 2 cycle Time () Time () 2 Fundamental (5Hz) = 127, THD= 8.8% 2 Fundamental (5Hz) = 196, THD= 8.8% Figure 18 how bar diagram of harmonic order of inut current. (With nubber) Figure 2: how the harmonic content in econdary current(with nubber) Selected ignal: 77.8 cycle. FFT window (in red): 2 cycle.6 Selected ignal: 77.8 cycle. FFT window (in red): 2 cycle Time () Time () 2 Fundamental (5Hz) = 593.2, THD= 8.13% 15 Fundamental (5Hz) = 593.2, THD= 8.13% Figure 21.how the harmonic content in econdary current (without Snubber) Figure 19: how the harmonic content in econdary current(without nubber) 96

8 Mag (% of Fundamental) International Journal of Recent Develoment in Engineering and Technology Webite: (ISSN (Online)) Volume 2, Iue 3, March 214) Figure 22how the harmonic content in econdary current (with Snubber) V. RESULT & COMPARISION During imulation of Fly back converter with nubber & without nubber the rimary & econdary current contain harmonic. In both the cae there wa harmonic which can be removed by a uitable filter circuit. From the imulation tudy we found the witch tre i around 12v without nubber circuit, where a by uing nubber circuit the tre wa reduced uto 4 v. Without Snubber V IN =12v V OUT=6v I 1 =1.5a I 2=.5a V SW =11v Selected ignal: cycle. FFT window (in red): 2 cycle Time () Fundamental (5Hz) = 196, THD= 8.8% with Snubber V IN=12v V OUT=13v I 1=1.5a I 2=1.2a V SW=5v VI. CONCLUSION Aim of the thei i to imulate and hardware deign of fly back converter. Accordingly imulation ha done with fly back converter without nubber and fly back converter with nubber. The Reult found that during imulation of fly back converter with nubber give better outut voltage and current and voltage tre acro the witch i alo le. Fly back converter with unique configuration aimed to increae the efficiency and erformance of tandard fly back converter. The rooed configuration integrate DC-DC tage and PFC tage of a fly back converter and rovide ower converion in one tage. The rooed converter deigned for 9 Watt. Thi ower level need more attention in deign and imilar commercial roduct in thi ower level i high cot device. The rooed converter reduce the comonent count, the ize and cot of the converter. In thi thei, analytical olution aroved the oeration ytem of the converter, however the imulation and exerimental verification howed that erformance could not give rooed erformance value of the reearch. The reearch ugget everal different value for aive element and finally ome limit are defined for thee arameter. REFERENCE [1] S. Y. Teng, C. T. Hieh and H. C. Lin, Active clam interleaved flyback converter with ingle-caacitor turn-off nubber for tunning oultry alication, in Proc. IEEE PEDS Conf., 27, [2] A. Bakkali, P. Alou, J. A. Oliver and J. A. Cobo, Average modeling and analyi of a flyback with active clam toology baed on a very imle tranformer, in Proc. IEEE APEC Conf., 27, [3] Y. Xi, P. K Jain, G. Joo and Yan Fei Liu, An imroved zero voltage witching flyback converter toology, in Proc. IEEE PESC Conf., vol. 2, 1998, [4] Keith Billing, Switchmode Power Suly Handbook, McGraw-Hill Profeional.D.M. Mitchell, Switching Regulator Deign & Analyi, ditributed by E/J Bloom Aociate, 2. [5] L. L. Fang, Y. Hong, Power Electronic: Advanced Converion Technologie, CRC Pre, 21 [6] R. Redl, L. Balogh, and N. O. Sokal, A new family of ingle tage iolated ower factor corrector with fat regulation of the outut voltage, in Proc. IEEE-PESC 94 Annu. Meeting, 1994, [7] C. Qiao, K.M. Smedley, A toology urvey of ingle-tage ower factor corrector with a boot tye inut-current-haer in Proc. IEEE Al. Power Electron. Conf. (APEC), Feb. 2, [8] Q. Zhao, F.C. Lee, F. Tai, Voltage and current tre reduction in ingle-tage ower factor correction ac/dc converter with bulk caacitor voltage feedback IEEE Tranaction on Power Electronic, Vol. 17, No. 4, July 22. [9] L. Huber and M.M. Jovanovic, AC/DC flyback converter, U. S. Patent No , Set. 25 [1] V. Vorerian, Simlified analyi of PWM converter uing model of PWM witch Part 2: dicontinuou conduction mode IEEE Tranaction on Aeroace and Electronic Sytem, Vol. 26, g ,