Single-Switch High Power Factor Inverter for Driving Piezoelectric Ceramic Transducer

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1 Single-Switch High Powe Facto Invete fo Diving Piezoelectic Ceamic Tanduce Hung iang Cheng * Chun An Cheng ** Chun Chieh Fang Hau Chen Yen Depatment of Electical Engineeing, Depatment of Electical Engineeing, I-Shou Univeity Fotune Intitute of Technology, Kaohiung County, Taiwan, R.O.C Kaohiung County, Taiwan, R.O.C. * hlcheng@iu.edu.tw, ** cacheng@iu.edu.tw yen@cente.fotech.edu.tw Abtact A novel cot-effective and high-efficiency ingle-witch eonant invete with powe-facto-coection (PFC cheme i popoed to dive a piezoelectic ceamic tanduce (PCT fo an ultaonic cleane. The cicuit topology i deived by integating a flyback convete eved a PFC tage with a cla-e eonant invete fo diving a thin PCT at it eonance fuency. A unity powe facto i achieved by opeating the flyback convete in dicontinuou conduction mode (DCM. With tactfully deigned cicuit paamete, the cla-e eonant invete i opeated at the uboptimum mode to minimize witching loe of the active witch, leading to high cicuit efficiency. The active witch i contolled by pule-width modulation at a fixed witching fuency and contant duty atio to adjuting the output powe of the PCT. The opeation mode, deign uation and tep fo the cicuit paamete ae popoed. A pototype cicuit deigned fo a 4-W ultaonic cleane wa built and teted to veify the analytical pediction. Satifactoy pefomance ae obtained fom the expeimental eult. Keywod-flyback convete; powe facto; ingle-tage; ultaonic tanduce I. INTRODUCTION Ultaonic cleane ue ultaound taveling though liquid to emove contaminant and depoit fom mateial uface, hole and cack. They ae widely employed fo cleaning glae, contact len, jeweley, watche, dentue and electonic uipment, etc. Uually, piezoelectic ceamic tanduce (PCT ae adopted a the vibation ouce fo the ultaonic cleane []-[3]. When PCT i activated by a cuent ouce of which fuency i ual to it mechanical eonance fuency, it vibate and ceate ultaonic wave though liquid to poduce the o-called caviation bubble. Thee poduced bubble could penetate viible and inviible hole, cack, and ecee, and emove tightly adheing o embedded paticle fom mateial uface. A compaed to othe cleaning olution, uch a chemical-baed cleaning method, ultaonic cleane ae moe envionmentally fiendly and have poved to be a moe effective olution. Owing to the benefit of high powe conveion efficiency and imple cicuit topology, the eonant invete ae pefeed and populaly ued to geneate a high-fuency inuoidal cuent to dive piezoelectic ceamic tanduce []-[3]. Among vaiou type of eonant invete, cla-e eonant invete ha vey imple tuctue and ue only one active powe witch and le component count. It make the cla-e eonant invete a cot-effective and light-weight olution fo low powe application [4], [8]-[]. Conventionally, high-fuency invete ue a diode-bidge ectifie with a bulky capacito to obtain moothed dc-link voltage fo the invete tage. Such a ectifie cicuit inevitably daw an input cuent of naow pule, eulting in eiou total cuent hamonic ditotion (THD and poo powe facto. To confim with hamonic egulation and to impove the powe facto, an additional powe conveion tage, called the powe-facto-coection (PFC tage, become neceay. Howeve, the additional PFC tage inceae the oveall cicuit cot, beide educing eliability and efficiency. Thee poblem can be olved by integating the PFC tage into the invete tage [5]-[]. Some ingle-tage high-fuency invete ae obtained by integating a PFC tage with a cla-e eonant invete. They ue buck-boot convete o boot convete to pefom PFC [8]-[]. It i noted that the dc-link voltage of a buck-boot typed o boot type PFC convete hould be high enough to enue opeating in DCM to achieve a high powe facto. Nevethele, one hould be awae that the peak voltage on the active witch of a cla-e eonant invete i uually many time of the dc-link voltage. Uing a flyback convete a a PFC tage eem to be a bette appoach when it i integated with a cla-e eonant invete, ince the dc-link voltage can be effectively educed by chooing pope tanfome tun-atio. In thi pape a ingle-tage high-powe-facto eonant invete fo diving PCT baed on the integation of a flyback convete and a cla-e eonant invete i peented. Only one active witch and one contol cicuit ae ued. The popoed cicuit achieve a high powe facto by opeating the flyback convete in DCM. Meanwhile, it featue high efficiency when the cla-e eonant invete i opeated at uboptimum mode [4]. II. CIRCUIT CONFIGURATION AND OPERATION A. Cicuit Configuation Fig. i the popoed ingle-tage eonant invete fo an ultaonic cleane. It i deived by integating a flyback 57

2 convete and a cla-e eonant invete. The flyback convete i compoed of tanfome T, diode D 5, active witch S, and dc-link capacito C dc. It pefom PFC function by wavehaping the input cuent to be inuoidal and in phae with the ac input voltage. Beide, it povide a moothed dc-link voltage fo the cla-e eonant invete ued to dive the PCT. The cla-e eonant invet i fomed by inducto, diode D 6 and D 7, S, C dc, capacito C, eonant cicuit (, C, C p and a PCT. Diode D 6 i ued fo iolating the ac input voltage and cla-e eonant invete. The pupoe of diode D 7 i to povide a path fo the eonant cuent i. A hown, witch S play the ole of the active witch fo both the flyback convete and cla-e eonant invete. Theefoe, only one active witch and accodingly only one contol ae uied. A mall low-pa filte, m and C m, i ued to emove the high-fuency cuent hamonic to obtain a inuoidal cuent at the input line. B. Cicuit Opeation To fulfill a high powe facto, the flyback convete i opeated in DCM at contant fuency and contant duty atio ove an input line-fuency cycle. Switch S i tuned on and off by a gated ignal v g with an adjutable duty atio to contol the input powe, theeby, contol the tanduce output powe. In ode to educe witching loe, the cla-e eonant invete i delibeately deigned to opeate at ub-optimal mode. It mean that the eonant cuent i will flow though D 7 pio to tuning on S. The enegy toed in C i almot dichaged. Hence, the witching-on loe of S can be effectively educed. Fo implifying cicuit analyi, following aumption ae made: All the cicuit component ae ideal. The witching fuency f i much highe than the input line fuency f, theefoe, input voltage can be conideed contant duing a high-witching cycle. 3 The dc-link capacitance C dc and the inductance ae aumed lage enough, thu the dc-link voltage, V dc, and the dc cuent, I dc, can be conideed ideal voltage and cuent ouce, epectively. 4 The loaded quality facto of the eonant cicuit i high enough o that the eonant cuent i i appoximately inuoidal. Figue. Popoed ingle-tage ingle-witch eonant invete. In accodance with the conducting tatu of the powe witche, the cicuit opeation can be divided into five mode. The uivalent cicuit fo each mode i hown in Fig.. The low-pa filte i neglected fo implification. Fig. 3 how the theoetical wavefom. The opeation i decibed a follow: Mode (t 0 < t < t : Pio to mode, S i off, and diode D 7 i conducting. The cuent of D 7 i the diffeence between the dc cuent I dc and the eonant cuent i. Thi mode begin when S i tuned on. The ectified line voltage i impoed on the pimay winding of tanfome T. Since the flyback convete opeate in DCM, the pimay cuent i inceae linealy fom zeo with a lope popotional to the ectified line voltage. Meanwhile, the cuent i - I dc flow though D 7 to clamp the voltage aco C at almot zeo voltage. Duing thi mode, the input cuent i in i ual to i. Mode end when the diffeence between I dc and i become poitive to tun off D 7. Mode (t < t < t : In the beginning of Mode, the cuent I dc - i natually commutate fom D 7 to S. Both the cuent I dc - i and i flow though witch S. The ectified line voltage i applied on the pimay winding of tanfome T and i inceae continuouly. Mode 3 (t < t < t 3 : Pio to Mode 3, cuent i eache a peak value. Thi mode begin when S i tuned off. Cuent i dop to zeo damatically at the witching-off intant. At thi moment, the cuent in the econday winding i i induced to keep the magneto-motive foce in tanfome T balance in ampee-tun. N i t = i t ( ( ( + N whee N and N ae the tun of the pimay and econday winding; t - and t + ae the time ight befoe and afte S i tuned off. Theeafte, i flow though D 5 to chage the dc-link capacito C dc. In thi time inteval, the voltage aco the econday winding i ual to -V dc. Hence, i deceae linealy. In the meantime, I dc - i commutate fom S to chage capacito C. At the beginning, I dc - i i poitive and voltage v C ie. When I dc - i become negative, v C tat to decline. Since the peak of i i popotional to the ectified input voltage v ec, the duation fo i declining to zeo i not contant but vaie with v ec. Thu, thee ae two poible mode following mode 3, depending on which of i o v C eache zeo fit. Mode 4-a (t 3 < t < t 4 : When the line voltage i high, v C decline to zeo befoe i doe, a illutated in Fig. 3(a. Mode 3 end at the time when v C become zeo, and then, the cicuit opeation ente mode 4-a. At thi intant, the cuent I dc - i natually commutate fom C to D 7. The voltage aco C i clamped to the diode fowad voltage (-0.7 V. In thi mode, i deceae continuouly. Thi mode end when i deceae to zeo. 57

3 .... Mode 4-b (t 3 < t < t 4 : At lowe line voltage, the peak of i i malle and decline to zeo fate, a illutated in Fig. 3(b. In cae that i deceae to zeo, Mode 4-b, intead of Mode 4-a, follow mode 3. D 5 i tuned off. Duing thi mode, cuent I dc - i flow though C continuouly. Thi mode end at the time when v C eache zeo. Then, cuent I dc - i natually commutate fom C to D 7. Mode 5 (t 4 < t < t 5 : Duing thi mode, cuent I dc - i flow though D 7 and v C i clamped at almot zeo voltage. At thi moment, the enegy toed in C i fully dichaged. When witch S i tuned on again by the diving ignal v g, thi mode end and the opeation etun to mode of the next cycle. v g d T I dc i I dc -i i S i D7 i i i C t 0 t t t 3t 4t 5 v C Mode 3 4-a 5 (a Figue 3. Theoetical wavefom when input voltage i at (a high level, (b low level. Duing mode and mode, the line ouce upplie cuent to flyback convete. The unfilteed input cuent i ual to i. Becaue the flyback convete i opeated in DCM, i inceae fom zeo at the beginning of mode and eache it peak at the end of mode. Theeafte, i dop damatically to zeo when S i tuned off. The wavefom of i and the input cuent i in ae conceptually hown in Fig. 4. The peak value of i follow a inuoidal envelope and can be expeed a: (b Figue. Opeation mode. III. CIRCUIT ANAYSIS Baed on the opeation decibed above, thee i not any inteaction between the flyback convete and the cla-e eonant invete, even though they hae an active witch. Theefoe, thi popoed ingle-tage eonant invete can be teated a two independent tage, the flyback convete and the cla-e eonant invete. A. Flyback PFC Convete The ingle-tage eonant invete i upplied fom an ac line voltage ouce. v ( t = V in( π f t ( in m whee f and V m ae fuency and amplitude of the line voltage, epectively. i,peak VdT m in( π ft ( t =. (3 whee T i the high-fuency witching peiod, d i the duty atio, and T i the inductance of the pimay winding of T. Cuent i i a pulating wavefom and ha hamonic component ditibuted ove the multiple of the witching fuency. The high-fuency content of i can be filteed out by the input filte m -C m with a cutoff fuency much lowe than the witching fuency. Then, the input cuent i in i ual to the aveage of i ove a high-fuency cycle. T VTd iin t i t d t in f t T 0 (4 T T m ( = ( ( = ( π Equation (4 eveal that the input cuent i inuoidal and in phae with the input line voltage if the witching fuency and duty atio emain contant ove an entie input line cycle. A a eult, a high powe facto can be achieved. The input powe can be obtained by taking aveage of the input powe ove one line-fuency cycle. π dvt m Pin = v ( ( ( 0 in t iin t d π f t π = (5 4 To fulfill a high input powe facto, the flyback convete mut opeate in DCM ove the input voltage cycle. It mean that the tanfome econday cuent hould decline to zeo T 573

4 Figue 4. Conceptual wavefom of i and i in. befoe the next tun-on of the active witch. It uie the dc-link voltage V dc be high enough to meet the following inuality uation. Figue 6. Equivalent cicuit of cla-e eonant invete. V dc N dv N m ( d (6 B. Cla-E Reonant Invete The PCT i pat of the component in the load eonant cicuit. It uivalent cicuit model conit of tatic capacity Co, uivalent acoutic eitance R m, uivalent mechanical inductance m and uivalent mechanical capacity C m, a hown Fig. 5 []-[3]. Thee cicuit paamete can be detemined by an impedance analyze. The mechanical eonance fuency f m i ual to / π mcm. At thi eonance fuency, PCT can be model a C o in paallel with R m. Fig. 6 how the cla-e eonant invete whee the PCT i eplaced by it uivalent electical model. The implified uivalent cicuit fo the load eonant cicuit in Fig. 6 can be obtained tep by tep, a hown in Fig. 7. The cicuit paamete in Fig. 7 ae expeed a: R C Cpo = Cp + Co (7 C R = (8 + ω m RmC po + ω RmC po ωrc m po = (9 C C = C + C whee the angula fuency ω = π f. Figue 5. (0 = ω C ( Equivalent cicuit model of piezoelectic ceamic tanduce. Figue 7. Step fo obtaining implified uivalent cicuit fo the load eonant cicuit. The analyi of the cla-e eonant invete can be pefomed on the implified uivalent cicuit. The loaded quality facto of the eonant cicuit i defined a: Q = R. ( C With a high loaded quality facto, the eonant cuent i i appoximately inuoidal. Auming i lead v g by an angle φ, i can be expeed a: i( ωt = Iin ( ωt (3 whee I i the amplitude of i. The combination of the inducto and the eonant cicuit act a a cuent ouce with a value ual to I dc i. Thi cuent flow though S when S i on. Othewie, it flow though the capacito C o diode D 7. When I dc i flow though C, the voltage aco C can be expeed a: vc ( ωt = { Idc( ωt πd + I co( ωt φ co( πd φ } ωc + + (4 In ode to eliminate witching-on loe, it i pefeed to tun on S at v C = 0 and i C = 0. In othe wod, both v C and i C hould be zeo at ω t = π. Subtituting vc ( π = 0 into (4, I can be obtained a: π ( d I= Idc (5 co( π d coφ Subtituting the bounday condition ic ( π = 0 i.e, dvc ( t d ( t = 0 at ωt = π and (5 into (4, φ can be obtained. 574

5 co( πd ( d + in( πd φ = π + tan π (6 When both the bounday condition of vc ( π = 0 and ic( π = 0 ae atified, S can be tuned on without any witching loe. It claim that the cla-e eonant invete opeate at the optimum mode. Baed on thee bounday condition, the component paamete R, C, and fo fulfilling the optimum mode hould meet the following uation [4]: in ( πd in ( πd R = V dc (7 π ( d P = R ( π ( π ( π ( d πco( πd in( πd ω R π ( d in d co d in d + C = ( d π + coφco( πd co ( πd co( πd π( d in( πd 4ωin( πd co( πd in( πd ( d πco( πd + in( πd whee P o i the tanduce output powe. IV. EXPERIMENTA RESUTS o (8 (9 To veify the opeation pinciple and theoetical analyi of the popoed novel ingle-tage ingle-witch eonant invete fo an ultaonic cleane, a pototype cicuit wa deigned and built to dive a 4 W PCT. The PCT i of dik type with 50 mm (diamete x.5mm (thickne in ize. An impedance analyze (HP494 i ued to meaue the paamete of the uivalent cicuit. The meauement i made with the PCT edge and the liquid filled containe oldeed togethe. Followed ae the tet eult: C o = 0.6 nf, R m = 30 Ω, m = 3 mh, C m = 7 pf, f m = 4 khz. The cicuit pecification and paamete ae lited in Table I. The dc-link voltage hould be highe than 03.3 V to atify (6. Hee, V dc = 0 V i choen with a ufficient afety magin. Fig. 8 how the input line voltage and cuent wavefom. They ae inuoidal and in phae with each othe. The meaued powe facto i geate than 0.99 and the total cuent hamonic ditotion (THD i 3.8%. Fig. 9 how the high-fuency wavefom of tanduce voltage and cuent at an output powe of 39.5 W. At thi powe, many fine bubble ae occued within one minute to poceed the cleaning poce. Fig. 0 how the pimay and the econday cuent of flyback tanfome. It can be obeved that the flyback convete opeate at DCM ove the entie cycle of the line ouce. The expeimental eult hown in Fig. demontate that the active witch S i tuned on when the TABE I. CIRCUIT SPECIFICATIONS AND PARAMETERS Input line voltage, v in Switching fuency, f Output Powe P o 0 V m, 60 Hz 4 khz 4 W Duty atio, d 0.4 DC-link voltage, V dc PCT R m PCT C o Capacitance, C dc Inductance, Tanfome inductance, T and T Capacitance, C Inductance, Capacitance, C Capacitance, C p 0 V DC 30 Ω 0.6 nf 00 uf 0 mh 0.57 mh, 0.57 mh. nf.4 mh 0.8 uf.6 nf capacito voltage v C i zeo. It effectively educe the witching-on loe. A high cicuit efficiency of 93% i achieved. Howeve, it hould be noted that the ectified input voltage i applied on S befoe witching on. The paaitic capacitance of S may caue cuent pike at the witching-on intant of S. Thee pike eult fom dichaging the paaitic capacitance at witching-on intant and intoduce loe and noie. Hence, in ode to futhe impove the cicuit efficiency, an active witch with a mall paaitic capacitance can be ued. Figue 9. v in v in : 00 V/div, i in : A/div, Time: 5 m/div Figue 8. v T i in Input line voltage and cuent. i T v T : 00 V/div, i T : A/div, Time: 0 u/div Piezoelectic ceamic tanduce voltage and cuent. 575

6 i i i i : A/div, Time: 5 m/div (a and a cla-e eonant invete output tage. Only one active witch and le cicuit component ae uied. The flyback convete i opeated in DCM to povide unity powe facto and low THD while the cla-e eonant invete dive the PCT at a fuency ual to it mechanical eonance fuency. By opeating the cla-e eonant invete at uboptimum mode, the active witch i tuned on afte the capacito i fully dichaged. Theefoe, the witching loe can be effectively eliminated, leading to high cicuit efficiency. A pototype cicuit deigned fo a 4-W PCT wa built and meaued to veify the theoetical analyi. Expeimental eult pove that almot unity powe facto and vey low THD can be achieved. The cicuit efficiency i The popoed topology wok a a good olution to implement low cot and high powe facto ultaonic tanduce. i i Figue 0. v g v d v C i S i i : A/div, Time: 5 m/div (b Tanfomwe cuent (a in ome line-fuency cycle (b in ome high-fuency cycle. v g : 0 V/div, v d, v C : 500 V/div, i S :5 A/div, Time: 0 u/div Fig. Wavefom of v g,v d,v C i. V. CONCUSIONS A novel ingle-tage ingle-witch eonant invete fo an ultaonic cleane ha been peented. The popoed cicuit i deived by integating a flyback convete ued a PFC tage REFERENCES [] R. Nagaajan, M. Diwan, P. Awathi, A. Shukla, P. Shama, M. Goodon, and S. Awad, Optimization of ultaonic cleaning fo eoion-enitive micoelectonic component, in Poc. IEEE/SEMI ASMC 006, 006, pp [] C. Buai, and A. Jangwanitlet, Compaion of witching tategie fo an ultaonic cleane, in Poc. IEEE ECTI-CON 008, 008, pp [3] P. Fabijanki, and R.agoda, Seie eonant convete with piezoelectic ceamic tanduce and fuzzy logic contol with genetic optimization, in Poc. IEEE EUROCON, 007, pp [4] M. K. Kazimieczuk and D. Czakowki, Reonant Powe Convete, New Yok: Wiley, 995. [5] D. D. C. u, H 0.5cm. H.C. Iu, and V. Pjevalica, A ingle-tage ac/dc convete with high powe facto, egulated bu voltage, and output voltage, IEEE Tan. on Powe Electon., vol. 3, no., pp. 8 8, Jan [6] R. T. Chen, Y. Y. Chen, and Y. R. Yang, Single-tage aymmetical half-bidge egulato with ipple eduction technique, IEEE Tan. on Ind. Electon., vol. 3, no. 3, pp , May [7] M. S. Agamy, and P. K. Jain, A thee-level eonant ingle-tage powe facto coection convete: analyi, deign, and implementation, IEEE Tan. Ind. Electon., vol.56, no.6, pp , Jun [8] C. S. in and C.. Chen, A ingle-witch oft-witching electonic ballat with high input powe facto, in Poc. IEEE ISIE 96, 996, pp [9] C. icital,. Maleani, G. Spiazzi, P. Tenti, and A. Teta, Single-ended oft-witching electonic ballat with unity powe facto, IEEE Tan. on Ind. Appl., vol. 9, no., pp , Mach/Apil 993. [0] M. Ponce, J. Aau, A. opez, J. Coea, and J. M. Alono, A novel high-powe-facto ingle-witch electonic ballat fo compact fluoecent lamp, in Poc. IEEE APEC 00, 00, pp [] Ying-Chun Chuang and Hung-iang Cheng, Single-tage ingle-witch high-powe-facto electonic ballat fo fluoecent lamp, IEEE Tan. Ind. Appl., vol.43, no.6, pp , Nov./Dec [] P. Fabijanki, and R.agoda, Genetic Identification of Paamete the Sandwich Piezoelectic Ceamic Tanduce fo Ultaonic Sytem, in Poc. IEEE EPE-PEMC 008, 008, pp [3] S. in, Study on a new type of adial compoite piezoelectic ultaonic tanduce in adial vibation, IEEE Tan. Ultaonic, Feoelectic, and Fuency Contol, vol. 53, no. 9, pp , Sep