CONTROLLING FREQUENCY INFLUENCE ON THE OPERATION OF SERIAL THYRISTOR RLC INVERTERS

Size: px

Start display at page:

Download "CONTROLLING FREQUENCY INFLUENCE ON THE OPERATION OF SERIAL THYRISTOR RLC INVERTERS"

Ross Paul
5 years ago
Views:

1 EETRONIS - September, Sozopol, BUGARIA ONTROING FREQUENY INFUENE ON THE OPERATION OF SERIA THYRISTOR R INVERTERS Evgeiy Ivaov Popov, iliya Ivaova Pideva, Borislav Nikolaev Tsakovski Departmet of Power Electroics, Techical Uiversity of Sofia, Kl. Ohridski Street No.8, Sofia, Bulgaria, phoe: , epopov@tu-sofia.bg Keywords: serial iverters, frequecy ifluece, cotrollig characteristics The ifluece of the cotrollig frequecy o the operatio ad parameters of the serial thyristor R iverters is studied. The autoomous bridge cofiguratio of the serial thyristor R iverter without free wheelig diodes is cosidered. The semicoductor device ca also be a combiatio of a trasistor ad a diode coected i series. Two suitable parameters are itroduced that are the Q * factor of the iverter circuit (frequecy idepedet) ad the frequecy coefficiet. The meaig of the last is wideed for oscillatory, overdamped ad critical modes of operatio. The relatios betwee this couple of parameters ad the load coefficiet B, power factor cosϕ couple are give. The chart i the (,Q * ) plae determies the iverter mode of operatio. The frequecy characteristics amely the output characteristics, the iput characteristics, the recovery characteristics, the klirrfactor characteristics ad the peak thyristor voltage characteristics are obtaied as fuctios from (,Q * ) parameters ad graphically displayed.. INTRODUTION I most practical cases the mai cotrollig variable of the autoomous iverters is the cotrollig (switchig) frequecy of the semicoductor devices ω=πf []-[5]. The ifluece of the cotrollig frequecy o the parameters ad characteristics of the curret-fed iverters is studied i [], []. The cotrollig frequecy characteristics of the serial thyristor iverters for iductio heatig are obtaied i []. The frequecy characteristics of a trasistor iverter operatig with a frequecy higher tha the resoace oe are give i [3]. The ifluece of the cotrollig frequecy at resoace iverters is studied i [5]. O the other had o the basis i [6] the geeralized characteristics of the serial thyristor R iverters are obtaied i [7] ad are cofirmed i [8]. They express i a implicit form the ifluece of the cotrollig frequecy. The ame serial thyristor R iverters is applied for all the iverters havig the structure show i Fig.. Their buildig device is either a thyristor without a free-wheelig diode coected i ati-parallel or a trasistor ad a diode coected i series. The ifluece of the cotrollig frequecy o the operatio ad characteristics of semicoductor R iverters is studied i [9]. It is ot kow a full study of the ifluece of the cotrollig frequecy o the parameters of the serial thyristor R iverters for differet modes of operatio icludig the overdamped ad critical character of the circuit to exist. The objective of the preset scietific report is a uified, complete ad i a explicit form study of the ifluece of the cotrollig frequecy o the parameters of

2 EETRONIS - September, Sozopol, BUGARIA the serial thyristor R iverters for differet modes of operatio to be carried out ad the frequecy characteristics to be derived.. PARAMETERS OF THE INVERTER IRUIT The iverter circuit is of secod order ad is described by the parameters quality factor Q * ad frequecy coefficiet. They ca be expressed by the parameters of the iverter (Fig. ) o oe had ad by the load cofficiet B ad the power factor cosϕ o the other i the followig maer: () * cos ϕ Q = = R cosϕ B () ω = =, Ω cb siϕ cb cos ϕ where Ω is the geeralized frequecy that for oscillatory character of the circuit ( R < ) is the iheret resoace frequecy Ω = ω = δ, for overdamped character ( R > ) it is the quasi-resoace frequecy Ω = δ ad for critical character ( R = ) it is the dampig coefficiet R Ω = δ =. The coefficiets c ad c have the followig values: for oscillatory character c=c =, for overdamped character c=c =-, for critical character c= c =-. The parameters Q * ad Ω are frequecy idepedet while expresses directly ad explicitly the ifluece of the cotrollig frequecy. Q * ca be expressed directly by the kow coefficiet of hesitatio k of the resoace iverters but it has a meaig also at overdamped ad critical character of the processes. All this shows the coveiece of the parameters ad Q * whe studyig the ifluece of the cotrollig frequecy ad derivig the frequecy characteristics. otrariwise, the parameters B ad cosϕ ca be expressed by ad Q * : (3) B = * c[ ] + ( Q ) * ( Q ) * c[ ] Q * ( Q ) c[ ] * ( Q ) () cosϕ =. c[ ] + ( Q * ( Q ) for oscillatory ad overdamped character of the circuit, ad * )

3 EETRONIS - September, Sozopol, BUGARIA (5) (6) for critical character. B = cosϕ = 3. MODES OF OPERATION HART + + The chart, showig the ifluece of the parameters B ad cosϕ o the iverter modes of operatio is give i [7]. Similar chart, showig the ifluece of the parameters ad Q * o the iverter modes of operatio is show i Fig.. I priciple both charts are equivalet.. INVERTER IRUIT STUDY Detailed study ad aalysis of the serial thyristor R iverters is doe i [6]. O this basis the geeralized characteristics are obtaied i [7] ad are cofirmed i ]8]. They express i a hidde form the ifluece of the cotrollig frequecy o the iverter operatio. A computer program is developed that processes the mathematical iformatio, determies the modes of operatio ad calculates the iverter parameters whe chagig the cotrollig frequecy (by varyig ) at differet quality factors Q * of the circuit. 5. RESUTS. FREQUENY HARATERISTIS The frequecy coefficiet is varied from. to. at a iterval of., while the quality factor Q * assumes the values.;.35;.5; ; ;. The followig frequecy characteristics are obtaied ad graphically displayed. Output characteristics (Fig. 3): I (7) OH = (8) (9) () Iput characteristics (Fig. ): IH Recovery characteristics (Fig. 5): N TQ = Klirrfactor characteristics (Fig. 6): k f [%] = I d U = d I Ω T d tq. c. I I I () () Peak thyristor voltage characteristics (Fig. 7): () UVSM = U VSm / U d

4 EETRONIS - September, Sozopol, BUGARIA I, I () are the RMS value ad the first harmoic RMS value of the iverter curret; t q.c. is the circuit tur-off time; T=/f is the period of the cotrollig pulses; U VSm is the peak thyristor voltage; U d, I d are the supplyig voltage ad curret. 6. ONUSION The results from the preset study ad from the geeralized characteristics coicide. The geeralized characteristics are experimetally cofirmed. Hece, the results from the study of the cotrollig frequecy ifluece ad the cotrollig characteristics derived are correct. The mathematical iformatio for calculatig the frequecy cotrollig characteristics could be applied for orgaizig a adequate digital cotrol system of the iverter. 7. REFERENES [] Nachev N., G. Maleev, Power Electroics, Techica, Sofia, 979 (i Bulgaria). [] Popov E., Automatic otrol of Serial Thyristor Iverters with Varyig oad, Ph.D. Thesis, VMEI, Sofia, 978 (i Bulgaria). [3] Bakov N., V. Kostova, oad haracteristics of a Trasistor Iverter Fuctioig with a Frequecy Higher tha the Resoace Oe, Proceedigs of the th Iteratioal Scietific ad Applied Sciece oferece EETRONIS ET, , Sozopol. [] Gradiarov N., Frequecy haracteristics of urret overters with omplex oad, Proceedigs of the th Iteratioal Scietific ad Applied Sciece oferece EETRONIS ET, , Sozopol. [5] Gradiarov N., Study, Developmet ad Progress of Autoomous Resoat Iverters for Electrical Techological Applicatio, D.Sc. Thesis, Sofia, (i Bulgaria). [6] Popov E., Ivestgatio ad Aalysis of Serial Thyristor R Iverters, Electrical Egieerig ad Electroics, uder prit (i Bulgaria). [7] Popov E., Geeralized haracteristics of Serial Thyristor R Iverters, Proceedigs of the Nith Natioal Scietific ad Applied Sciece oferece with Iteratioal Participatio EETRONIS ET, Sozopol, Bulgaria, September (i Bulgaria). [8] Popov E., A. Popova, Study of Serial Thyristor R Iverters. Normalized Examples, Proceedigs of the Eleveth Natioal Scietific ad Applied Sciece oferece with Iteratioal Participatio EETRONIS ET, Sozopol, Bulgaria, September (i Bulgaria). [9] Popov E.,. Pideva, B. Tsakovski, otrollig Frequecy Ifluece o the Operatio of Semicoductor R Iverters, Proceedigs of the Twelfth Iteratioal Scietific ad Applied Sciece oferece EETRONIS ET 3, Sozopol, Bulgaria, September 3. i d VS VS i u U d R VS VS3 Fig.. A serial thyristor R iverter without free-wheelig diodes.

5 EETRONIS Q * oscilatory character - September, Sozopol, BUGARIA frequecy below the resoace (atural comutatio) discotiious iverter curret overdamped character resoace frequecy above the resoace (forced comutatio) cotiious iverter curret critical character cotiious iverter curret,,5,,5, Fig.. Modes of operatio chart. OH,,,,6,8,,,6,8 Fig. 3. Output characteristics. IH N,,,6,8,,,6,8, Fig.. Iput characteristics.

6 EETRONIS - September, Sozopol, BUGARIA,5,,3,,,5 TQ,,,,6,8,,,6,8 Fig. 5. Recovery characteristics k f [%],,,,6,8,,,6,8 Fig. 6. Klirrfactor characteristics UVSM,,,,6,8,,,6,8 Fig.7. Peak thyristor voltage characteristics.

MEASUREMENT AND CONTORL OF TOTAL HARMONIC DISTORTION IN FREQUENCY RANGE 0,02-10KHZ.

MEASUREMENT AND CONTORL OF TOTAL HARMONIC DISTORTION IN FREQUENCY RANGE 0,02-10KHZ. ELECTRONICS 00 September, Sozopol, BLGARIA MEASREMENT AND CONTORL OF TOTAL HARMONIC DISTORTION IN FREQENCY RANGE 0,0-0KHZ. Plame Agelov Agelov Faculty for Computer Sciece, Egieerig ad Natural Studies,