Development of A Cost Effective 2.5kva Uninterruptible Power Supply System

Transcription

1 American Journal of Engineering eearch (AJE e-ss: SS : olume-5, ue-, eearch Paer Oen Acce Develoment of A Cot Effective.5kva Uninterrutible Power Suly Sytem Olanrewaju Lateef Kadir, Okechi Onuoha, naemeka Chiemezie Onuekwui 3, Ufuoma Onochoja 4, Chikwelu ono Udezue 5,,4,5 (Project Develoment ntitute (PODA, igeria 3 (Federal Univerity of Technology, Owerri (FUTO, igeria ABSTACT : Thi aer i on the detailed develoment of a cot effective Uninterrutible Power Suly (UPS ytem for dometic ue. The UPS erve a a tandby / backu ower uly unit for ower uly from the main commercial uly line. n thi aer, an eay to imlement block diagram howing all the imortant unit of the UPS ytem i given. Detailed deign howing all calculation and conideration were alo included in thi work. Alo, a imle cot analyi howing the cot of roducing thi ytem from the cratch and alo the cot of a imilar roduct in igeria i alo hown. The UPS conit of charge a controlling ection, an inverting ection, an automatic change-over / witching ection a tranformation and a load ection. The battery i charged through a rectifier. The rectified DC outut wa achieved uing a bridge rectifier and a voltage regulator. The change-over wa done by an electric relay whoe function i to etablih connection between the load and either the main or the batterie. Keyword - zener diode; automatic change over; ocillator; national grid; low reluctance; battery bank. TODUCTO The imortance of electrical ower uly cannot be over-emhaized. t rovide lighting during the day to indoor area and to entire urrounding at night. The tak of generating and ditributing uninterrutible ower in develoing countrie eem to be imoible to olve by their government. A a reult, individual, buine center, comanie are trying to olve thi roblem on their own. One of the method ued in olving thi i the ue of mechanical generating lant which i uually called generator. The ue of generator a alternative ha limitation. Thee limitation include: high cot of oeration and maintenance; it caue a lot of environmental ollution; it roduce a lot of noie; and mot mechanical generator are bulky. Another method ued in olving the roblem i the uninterrutible ower uly (UPS. The UPS derive it ower from energy tored in a battery. The UPS i a better alternative than the generator in term of noie, environmental ollution and ize. The aim of thi article i develo an eay to oerate.5ka uninterrutible ower uly that will generate ower from battery. UPS i an electronic ytem or circuit that change direct current (DC tored in a battery to alternating current (AC. t i ued to uly continuou ower to the load connected to it outut ocket. The battery( will be charged by a rectifier circuit which conit of a tranformer, a bridge rectifier, a filter and a voltage regulator. n view of erratic ower, the UPS erve a a main to the houehold aliance or load connected to it. The article contain four ection. After thi introductory ection, ection two exlain the individual function of all the comonent of the circuit and how they oerate. Thi ection alo dicue the circuit deign calculation and decrition. Teting and erformance evaluation are reented in ection three and concluion and recommendation are drawn in ection four. w w w. a j e r. o r g Page 5

2 . DESG METHODOLOGY. Block Diagram of an uninterrutible Power Suly ectifier Unit Charging Controller Battery control Switch Ocillator/Driver Unit Tranformation Unit AC Main/Power Suly Unit Battery Change Over Unit Load Unit Fig..: Block Diagram of an Uninterrutible Power Suly Figure. how the block diagram of a UPS. Thi diagram wa ued in the deign calculation.. Load Unit The load unit i the outut unit of the UPS. Thi i where all the electrical ower conuming aliance are connected to the UPS. Thi unit make ue of a ocket outlet. A voltmeter may be included in the outut to dilay the outut voltage..3 Change-Over Unit At the changeover unit i a relay witch (L that wa incororated at the outut of the UPS to witch the ource of ower uly to the outut from either the battery or the uly main (national grid..4 Tranformation Unit n thi ection of the deign, a 4/40 te-u tranformer (T wa ued. The tranformer ha a centre ta which wa connected to the oitive terminal of the battery. Figure. how the circuit diagram for the 4/0 tranformation unit together with the driver, changeover and load unit. Fig..: Circuit Diagram for a 4/40 Tranformation/Change-over/Load Unit.4. Determination of the number of turn of coil on each ide of T winding Power rating of T wa.5ka. The volt er turn i given by E 4.44 fb A t max (. w w w. a j e r. o r g Page 6

3 Where E t i volt er turn, f i the frequency in Hertz, B max, i the maximum flux denity in tela, A i the lamination core area in m, (in volt i the rimary ide voltage, i the number of turn on the rimary ide, (in volt i the econdary ide voltage, i the number of turn on the econdary ide. The ize of the tranformer core mut be determined baed on the tranformer total ower. The area of the core hould at leat have the value according to the equation.. Therefore the area of lamination of tranformer T i given a A ower Watt cm (. A ower Watt 0 4 m (.3 A co 0 4 m (.4 Where Coө i the ower factor. Chooing a ower factor of 0.8 and maximum flux denity of lamination to be. Tela, the volt er turn i obtained uing equation 3. and 3.4. E t.93 volt / turn The exected outut voltage of T i 40. Secondary voltage of T i 40 The number of turn in the econdary winding ( i obtained uing equation.5 E t turn 0 turn (.5 Alo, the number of turn in the rimary winding ( i given a in equation.6 E t turn 0 turn (.6.4. Coil Gauge equired for T ecall, A (.7 Power Power rating of T i 500A, auming 90% efficiency. Then the inut rating i given by P i P out eff (.8 Where P i i the inut ower, P out i the outut ower and eff i the efficiency. oltage on the econdary ide i 40, thu, current in the econdary ide of T i P out 0.4 Amere From the America Wire Gauge (AWG, Gauge will be ufficient for the econdary coil. oltage on the rimary ide i 4, thu rimary current, w w w. a j e r. o r g Page 7

4 Pi 5.7 Amere From AWG, Gauge will be ufficient for rimary ide..5 Ocillator Unit The ocillator unit make ue of an C (CD4047 configured in a-table multi-vibrator for ule generation of 50Hz duration. Thi i hown in Figure.3 Fig..3: Ocillator Circuit The configuration i uch that in 4, 5, 6 and 4 were connected to cc while in 7, 8, 9 and were connected to the ground. The, and C network will determine the frequency of ocillator which i 50Hz. Pin 0 and in are the outut (Q and comlementary outut (Q- reectively and thi reult in the earation of ignal into two earate channel. Each channel wa connected to the gate of two earate ower MOSFET channel. Each channel of the MOSFET wa then connected to the end of the rimary ide of T. The C i to be rovided with a contant voltage from the battery through a voltage regulator C 78. The LED i to indicate when the inverter i working. and erve a limiting reitor to limit the current entering the gate of the MOSFET. The eriod T of the ocillator i given by T 4.4 C and T f ec (.0 f 4.4 C Where f i frequency which in thi cae i 50Hz. Chooing C to be 00nf, wa obtained to be equal to 45.5k Ω from equation.0 From the manufacturer data heet, when the voltage at in 4 i, the voltage and current outut at in 0 and in of C 4047CD are 5.6 and 50mA. out max GS (. Where out at in 0 and in of C 4047CD are 5.6, GS = 0 and max =50mA. From equation., = = 00Ω cc LED LED 4 (. Where cc = (from g, LED = and LED =0mA (from manufacturer ecification. From equation. 4 wa comuted to be kω w w w. a j e r. o r g Page 8

5 .6 Driver Unit Thi ection make ue of ower MOSFET FP50. The MOSFET ha a maximum current ( M and voltage of 30A and 00 reectively. Each outut of the ocillator wa connected to each channel of the MOSFET which reulted in the channel being alternatively O and OFF. The required number of ower MOSFET, m, wa obtained uing equation.8. m m (.3 Hence 4 MOSFET can afely handle the exected rimary current but 6 MOSFET wa recommended for higher reliability..7 Battery Control Switch Unit Thi unit i ued to diconnect the battery from the inverting ection whenever there i ower uly from the national grid. Thi unit make ue of relay witch..8 Charging Controller The charging controller i ued to rotect the battery from over drainage and over charging. The charging controller conit of low battery voltage tri unit and charging control unit..8. Low Battery Control Circuit Fig..4: Low Battery oltage Tri Circuit The low battery voltage tri i required to diconnect the battery from the outut when it voltage ha droed to certain level. Thi i to enure that the battery i not over drained by the UPS. Figure.4 how the circuit diagram for low voltage battery tri. Thi unit make ue of LM34 comarator (C and zener diode Z D Pin i the outut terminal. Pin i the non-inverting terminal. Pin 3 i the inverting terminal. Pin of the o-am i et to a contant voltage of +0 by Z D, while in 3 i et to 9 through otential divider formed by 5 and 6. A the battery voltage i dicharging, the voltage at in 3 will be reducing. When the voltage at in 3 become lower than the voltage at in, it reult to a high voltage at in which will bia the tranitor Q 5 through reitor 8. Thi trigger the relay connected to it thereby diconnecting the battery from ocillator. At in, the inverting terminal, cc 6 (.4 Where cc i the battery voltage w w w. a j e r. o r g Page 9

6 6 i the voltage acro the inverting terminal et to 9 by otential divider formed by reitor 5 and 6. Uing equation 3.4, 5 = 6 = kω At in 3 (non-inverting terminal, the zener diode Z D, i et to a voltage of 0. cc 7 ZD ZD (.5 Where ZD i the zener diode voltage, 0 and ZD i the zener diode current, 0mA. 7 i obtained to be kω The tranitor C85 (Q 5 ha the following ecification from the data heet. cmax = 0.5A, BEmax = 5, β = 00 Outut voltage of the o-am = 0.9 cc 3 Where cc3 i the voltage regulator outut voltage ulied to ower the o-am. Outut at in = Thu, BB cc 8 BB B BE (.6 and B C (.7 For LED 9 CC LED LED (.8 Where cc =, LED = and LED = 0mA. From equation.6,.7 and.8, 8 and 9 are obtained to be kω and kω reectively Diode D 3 i t ha a eak voltage of 50 and a maximum current of 7A; it can afely rotect the relay from invere voltage..8. Charging Controller Unit Fig..5: Charging controller circuit Thi tage i deigned to revent the battery from overvoltage charging. Figure.5 how the circuit diagram for charging controller unit. Two fully charged batterie were connected in erie giving a total voltage of 4. C 3 wa ued a a comarator in the charging controller unit. The inverting terminal wa fixed at a contant voltage of through zener diode Z D. Thu, CC ZD ZD (.9 w w w. a j e r. o r g Page 30

7 Where cc i the batterie voltage, ZD =, ZD = 0mA. i obtained to be.kω Once the batterie are fully charged, the voltage acro the non-inverting terminal i higher than that of the inverting terminal, thi will trigger the tranitor Q 6 connected to it. Thi diconnect the batterie from the charging ource. The charging ource i reconnected when the voltage at the inverting terminal i higher than the voltage at the non-inverting terminal. The non-inverting terminal i therefore et to 4 through otential divider formed by 0 and. Then, 0 CC OP OP (.0 Where cc i the batterie voltage, o + = 4 and 0 = kω. A reitor of kω i obtained for. Tranitor Q 6 (C85 ha the following ecification: cmax = 0.5A, BEmax = 0.7, β = 00 3 BB B BE (. B C (. BB CC 0.9 A reitance of kω i obtained for 3 D 4 i a 4007 diode with the following ecification: Peak invere voltage of 50, and maximum current of 7A. The diode were ued a rotector for the relay againt the invere voltage..9 ectifier Circuit The rectifier circuit conit of tranformer T, caacitor C and a voltage regulator a hown in Figure.6 Fig..6: ectifier Circuit T i rated at 0/30 and the bridge rectifier conit of four diode, D D4 (4007. The diode are ued to convert the ac voltage available at the econdary of the ower uly circuit to dc voltage. They have a eak invere voltage of 00, and a maximum current of 30Amere which can afely handle 30 T. Caacitor C i ued to filter the rile in the rectified voltage. The value of the caacitor deend on the load current and the degree of moothing required. The caacitor i elected baed on equation.3. w w w. a j e r. o r g Page 3

8 c C dv dt c (.3 Where C i the Caacitance of caacitor in Farad, dv c i the rile voltage ( roduced by the rectifier and dt i the time between eak of the inut waveform. t f ec ond Where f i the frequency in Hertz. The econdary current c of tranformer T i 6Amere. From equation.3, C i obtained to be 6000μF The voltage regulator, G i 785 C with maximum outut voltage of 5. The outut of the rectifier circuit i connected to the batterie for charging..0 Power Suly/ AC Main Unit The ower uly unit rereent the inut from the national grid. Thi unit i ued to rovide charging to the battery from the national uly grid. The AC inut i rectified to the required outut voltage to charge the battery through the rectifier circuit or unit. The UPS i made eay uch that the uly from the national main goe directly to the outut when the uly main i available. A changeover i incororated in the outut to witch between uly from battery and uly main from national grid without any noticeable interrution.. Battery Bank A battery i an electrochemical device that convert electrical energy to chemical energy during charging and chemical energy back to electrical energy during dicharging. A battery bank i needed in UPS deign to tore the energy when there i ower uly from the national grid. Dee cycle battery tye are recommended in UPS deign becaue they are ecifically deigned for charge and dicharge for a longer time. The battery hould be large enough to tore large amount of energy. Many ize of batterie are available in the market, ome include: /00A, /50A and /00A. The batterie can be connected in erie to increae their voltage caacity or connected in arallel to increae their current caacity. The batterie ued for thi UPS are connected in erie to roduce 4 outut. Figure.7 how the comlete circuit diagram of the.5ka UPS. Fig..7: Comlete Circuit Diagram of Power nverter w w w. a j e r. o r g Page 3

9 . PEFOMACE EALUATO The UPS wa teted tage by tage. The ytem outut voltage wa meaured at no load. Table 3. how the exected and meaured value. 3. Outut oltage Tet Table.: Outut oltage Tet Exected Outut oltage ( Meaured Outut oltage Correlation (% emark From Battery (nverter Mode From Commercial Main Suly Satifactory Satifactory 3. Over-Drain Tet Thi tet wa carried out to revent the batterie from too much draining i.e. to to dicharging when the voltage droed to certain level. The ytem wa owered O and the ocillator outut voltage wa meaured at different battery voltage. The reult i a hown in Table.. Table.: Over-drain Tet S/ Battery oltage ( Ocillator Outut ( Sytem Outut ( emark Satifactory Satifactory Satifactory Satifactory Satifactory 3.3 Charging Tet Thi tet wa carried out in order to enure that the charging current rovided from the charging ource doe not overcharge the batterie. The reult of the tet i a hown in Table.3. Table.3: Charging Tet S/ Battery oltage ( ndicator 8 0 O O The reult obtained from the 3 O tet were atifactory. 4 4 O 5 6 OFF 34 Outut Power/Load Tet The duration of uly from the UPS when there i no uly from the national grid i a function of total ower connected to it outut or load unit and ower rating or caacity of the battery. The battery caacity i 4, 00Amere hour (4/00Ah. The UPS wa teted with 000W halogen bulb. The dicharge duration i a hown in Table.4. w w w. a j e r. o r g Page 33

10 Table 3.4: Outut Power/Load Tet Power (Watt Outut oltage ( Duration (Hour hr, 5 minute hr, 5 minute 3.5 Cot mlication The develoment of thi UPS i alo cot effective. Table.5 how the rough etimate of cot of different comonent ued in the develoment of the UPS. Table.5: Cot of Comonent of the Power nverter Comonent Cot ( Tranformer T 5000 Tranformer T 4500 Diode and LED 500 oltage regulator 500 eitor 500 Caacitor 500 elay witche 000 FET 000 ntegrated circuit and ocket 500 Caing 5500 Socket and lug 800 Switche 500 Meter 600 Connecting wire 4000 Micellaneou 5000 TOTAL COST t will be oberved that the total cot of the UPS (53,400 i le than the elling rice of a imilar UPS here in igeria. The leat cot of a imilar UPS ytem here in igeria cot at leat 80,000. The cot of the UPS deigned in thi work will reduce ignificantly if the UPS i to be maively roduced.. COCLUSOS From the tet carried out on the UPS, it can be reolved that the main objective ha been achieved. The ytem outut voltage on O LOAD wa 43. when the battery voltage wa 4. From Table 3., the batterie toed dicharging when the voltage acro them droed below 8. From Table 3.3, the charging toed when the voltage of the erie connected batterie wa more than 4, thereby facilitating a reliable and efficient ue of the batterie. The UPS load/outut tet alo howed that the UPS can carry 000W (500A uccefully. Though the outut voltage wa een reducing a more load were connected, the duration of uly from the UPS deend on the ower of the connected load and the battery caacity. The duration can be increaed by increaing the battery caacity. w w w. a j e r. o r g Page 34

11 EFEECES [] obert Boyletad, Loui ahlky Electronic Device and Circuit Theory, Seventh Edition, Prentice Hall, Uer Saddle iver, ew Jerey, 003 [] orth Star Battery Oeration Manual, 009 [3] [4] Theraja B. L. and Theraja A. K. A textbook of Electrical Technology, ol, t Edition, S Chand & Comany Limited, 005. [5] Paul Horowitz, The Art of Electronic, Second Edition, Cambridge Univerity Pre, 009 [6] David. J and elm. M, Baic Engineering Circuit Deign Analyi, Eight Edition, Publihed by John Winley and Son, nc, 006 [7] w w w. a j e r. o r g Page 35