Pre/Post Charge Control using IGBT for Relay Contact Protection in Electric Vehicle

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Joseph Lindsey
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1 WSEAS TRANSATONS on POWER SYSTEMS Surahai Wongfookeat, Thanathai Kulworawanihpong Pre/Post har ontrol using GBT for Relay ontat Protetion in Eletri ehile Shool of Eletrial Engineering, nstitute of Engineering Suranaree University of Tehnology, University Avenue, Muang, Nakhon Rathasima THALAND Abstrat: - This paper fouses on solving the problem of relay ontat ar in an eletri vehile by using GBT. When a relay opens, interating high urrent, an ar is produed aross the relay ontats. The ar may melt and destroy the ontats. The GBT is used to lim it the in rush urrent from the battery to t he apaitor in the inverter when the system is turned ON. To shutdown the system, the GBT is also used to gradually redue the urrent to zero. This is ahieved by ontrolling GBT s gate volt a whih in turn ontrol s urrent flowing through the GBT. The simulation responses of the proposed system and the onvention system that uses a prehar relay in series with a resistor were ompared and analysed. With the propo sed ontrol system inrush urrents are signifiantly redued, solving the ar pr oblem. A prototype of the proposed system was built and tested, the test results proved that the proposed method gives the satisfatory response. Key-Words: - pre har, post har, indutive load, apaitive load, ontat ar, inrush urrent, sur volta ntrodution The most important om ponents in a pure eletri vehile inlude batteries used as ene rgy soure, tration motors used for p ropulsion, auxiliary loads suh as air onditioning unit, air om pressor, and steering pump, auxiliar y load unit used to suppl y power to the auxiliary loads, inverters used to ontrol motors, and ve ry important swithing devies alled power rela ys. Power relay s are used to turn ON the system (onneting the battery to the load) and to shut it down (disonneting the battery from the load). A protetive mehanis m is needed to prevent eletri ar aross relay ontats w hen the rela y loses or o pens. onventionally, in an eletri vehile, a pre-har rela y is onneted in series with a resistor to limit inrush urrent to the apaitor in the inverter. When the sy stem is tu rned on, the pre-har relay and negative relay are energized to pre-har the apaitor un til the inrush urrent subsides. Then, the positive relay is energized and the pre-har relay is de-energized []. But, if inverters are not O, t he onventional method annot limit the inrush u rrent when turn ON the system. To shutdown the system, all inverters must be turned O first. However, even if t he inverters are O but, so me indutive loads are still running, shutting down the s ystem may result to a sur volta aross relay ontat whih wil l ause ar and dama at the ontats. The ar an m elt relay ontats and ause a permanent lose, that is, the ontats annot be opened eletrially. This paper presents a solution to the relay ontats ar problem in high volta sy stems by using GBT transistor to limit inrush urrent when turning ON and limit the sur volta when turning O a system. GBT transistor modeling The GBT m odel is sh own in ig., when the volta is applied at the gate pin, drain urrent ( d ) of the MOSET transistor equals the base urrent ( b ) of the BJT transistor given by Equation (). The urrent through the GBT is given b y Equation (), the value for k is obtained under saturation ondition using Equation (). Thus Equation () an be rewritten as in Equation (5) []. E-SSN: 4-5X 6 olume, 7

2 WSEAS TRANSATONS on POWER SYSTEMS Surahai Wongfookeat, Thanathai Kulworawanihpong O. Thus, the sy stem runs with GBT O, positive and negative relays ON. ig. GBT Model d b k th () k th () bs k () bes es th bes es es K (4) s th bes es bes es K (5) th To shutdown the sy stem, the GBT is turned fully ON, and then the negative relay is turned O. The volta at the GBT gate is then graduall y dereased (to derease urrent flow) until the transistor is fully O. When the GB T is O, the positive relay is then turned O.. Pre harging The iruit shown in i g. is used to ontrol the GBT gate volta, enabling turning ON the system. When the volta is applied aross the apaitor, the GBT transistor i s partially turned ON (GBT gate volta is lim ited) limiting urrent flowing through it. This enables limiting load urrent when turning ON the system. System Design The proposed system is shown in ig.. The GBT is onneted in parallel with the negative relay to limit inrush urrent during turning ON and lim it the sur volta when shutting down the system. ig. Pre/Post har ontrol Struture To turn ON the sy stem, the positive relay is turned ON f irst while th e negative r elay and the GBT are O. Then, the GBT is partially turned ON to li mit the urrent fl owing into t he apaitor whih is in the inverter. The volta at the GB T gate is then gradually inreased to fully turn ON the GBT (reduing volta drop between olletor and emitter) allowing full load urrent to flow. Then the negative relay is turned ON and the G BT is turned ig. GBT gate volta ontrol turning ON iruit The proedure starts by applying the volta first and then the volta. The volta determines volta drop aross the optooupler, thus determining gate volta of the GBT whih in turn determines urrent flowing through the GBT. rom the GBT ontrol iruit shown in ig., the volta drop aross the output of the optooupler an be obtained from equation (6), the input urrent ( ) and the output urrent ( ) through the optooupler is given by Equation (7) and equation () respetively. Thus the gate volta ( ) an be obtained from Equation (9). The gate volta from Equation (5) equals Equatio n (9). Thus the relationship between the volta and urrent is given b y Equation (). The minimum value of resistor R is used [ ], to deter mine the w orst ase senario under the operation onditions. E-SSN: 4-5X 64 olume, 7

3 WSEAS TRANSATONS on POWER SYSTEMS Surahai Wongfookeat, Thanathai Kulworawanihpong R (6) e (7) R TR TR R R K TR R th R th K R TR R (8) (9) () () The volta aross the apaitor in the inverter is given by Equation (). rom Equation () the apaitor in the inverter harging by the onstant urrent, thus time deter mines how long the GBT should remain partially ON by Equation (). The value of apaitor an be obtained from Equation (). The harging tim e is 5 times ti me onstant ( ), thus the values of the resistor R and apaitor determine the tim e to turn ON the negative relay aording to the Equation (). t () R 5R (). Post harging To shutdown the system, only is applied to full y turn on the GBT and then the GBT ontrol iruit is de-energized, as the a paitor dishars, the GBT gate volta gradually dereases. urther explanations are given in the following subsetions. t t dt () t () The next st ep proedure is turnin g O the volta and still volta. The volta determines the volta drop aross the optooupler. The volta an be obtained from Equation (4) and Equation (5). Thus the urrent an be obtained by Equation (9). t R e (4) R (5) t R t e R R (7) t R TR e e R R (8) e R (6) t e R TR th (9) R K R ig.4 GBT gate volta ontrol turning O iruit The shutdown proedure starts by the GBT is turned ON to b ypass the urrent. This is done by applying volta, as the apaitor hars, the gate volta ( ) of the GBT inreases to full y turn ON the GBT. When the GBT is fully ON, the negative relay is de-energized. And then the GBT ontrolling iruit is de-energized, as t he apaitor dishars, dereases, when the volta beomes less than the thr eshold volta ( th ) the GBT is fully turned O. inally, the positive relay is de-energized. As the apaitor dishars, the volta will derease aording to the Equation (). The apaitane of the apaitor will determine by Equation (). Thus the values of the resistor R and apaitor determine the time to turn O the positive relay aording to the Equation (4). Designing the GBT o oling system is used [4]. t R e () E-SSN: 4-5X 65 olume, 7

4 WSEAS TRANSATONS on POWER SYSTEMS Surahai Wongfookeat, Thanathai Kulworawanihpong R () toff 5R (4) p (A) x Simulation and Experimental Result A onventional sy stem (ig.5) and the proposed system (ig.9) were both simulated usin g MATLAB/Simulink, and the results a re ompared. Simulation parameters were taken from an eletri bus alled PEA Ze-Bus that was reently developed in Thailand. The bus has 65, Ah Li-ion battery, 495 no-load apaitane ( ),.M no-load resistane ( R ),.8mH no-load indutane ( L ), 4 on-load resistane ( R ), and.h onload indutane ( L ). Ar power model to simulation is used [5]. 4. onventional System A onventional system that uses a pre-har relay in series with a urrent li miting resistor is shown in ig.5. As previously mentioned, parameters for the battery,, L, R, L, and R were taken fro m the PEA Ze-Bus. The pre-har relay is onneted in series with a resistor. p () Pp (W) ig.6 Response in the positive relay by onventional ontrol pre (A) pre () 6 4 ig.5 onventional ontrol system When the system is turned ON and O on load, the responses in the positive relay, pre-hard relay and load a re shown i n ig.6 through ig.8. Maximum urrent through the positive relay is 8 ka and the maximum ar power is.68 kw whih is very high, as shown in ig.6. Maxi mum urrent through the pre-har relay is 6. A, and the maximum ar power is 8 W with a sur during the shut-off as illustrated in ig.7. Ppre (W) ig.7 Response in the pre-har relay by onventional ontrol E-SSN: 4-5X 66 olume, 7

5 WSEAS TRANSATONS on POWER SYSTEMS Surahai Wongfookeat, Thanathai Kulworawanihpong L () L (A).5.5 x ig.8 Response to load by onventional ontrol 4. Proposed System The simulated proposed sy stem that u ses GBT to limit inrush urrent is shown in ig.9. The profile of the GBT gate volta is shown in ig.. With load onneted, the maximum urrent through the positive re lay is 8.97A and the maximum ar power is about. 45W as shown in ig.. Load urrent and volta profiles are shown in ig.. The load urrent rises to.5 A, when the positive relay starts and stops. p () p (A) Pp (W) ig. Response in the positive relay by GBT ontrol L (A) L () ig.9 Pre/Post har ontrol by GBT ig. Response to load by GBT ontrol () ig. Gate volta response of the GBT 4. Experimental Setup and Test Result This setion presents t est results of t he proposed system prototype. The pr ototype was built using GBT number GT6M whih has a maximum urrent of 6A, the saturation vol ta es of 9 and, the gate volta s of 5, is used [6], 5 D power suppl y,, u load a paitane, load resistane and H load indutane. Our iruit are ompose of optooupler number TLP5 [7], R of 9.4 k, R and R of k, and E-SSN: 4-5X 67 olume, 7

5 fr om whih it an be seen that, load urrent gradually inreases when the system is turned ON, and gradually dereases when the system is turned O, without any sur.

6 WSEAS TRANSATONS on POWER SYSTEMS Surahai Wongfookeat, Thanathai Kulworawanihpong of 47,, and of 5 D. The built prototype is shown in i g.. A o ntrolled volta used to ontrol GBT transistor is shown in ig.4. Load urrent and volta profiles are shown in ig.5 fr om whih it an be seen that, load urrent gradually inreases when the system is turned ON, and gradually dereases when the system is turned O, without any sur. Thus, eletri ar aross relay ontats is eliminated. The osillosope ould not be used to measure the volta aross the relay ontat beause the probes would t very hot and melt. ig.5 Response to the load by implementation 5 onlusion The paper presents a solution to the relay ontats ar problem in eletri vehiles by using GBT to limit inrush urrent when turni ng ON and O a system. Simulated in MATLAB/Si mulink, the proposed system was found t o give satisfatory results ompared to the onventional system that uses a pre-har relay in serie s with a resistor. A prototype of the propose d system was built and tested, the tested results also showed that the proposed system gives satisfatory results. ig. ontrol system ig.4 Gate volta to ontrol the GBT Referenes: [] D. Andrea. Battery Manament Systems for Lar Lithium-on Battery Paks. Norwood MA: Arteh house,, pp [] H. Hollander, Modeling of an GBT and a Gate Unit, M. S. Thesis, Royal nstitute of Tehnology Shool of Eletrial Engineering, Stokholm, SE,. [] ishay, Optoouplers and Solid-State Relays, Appl. Note 45, ishay ntertehnology, Ot.. [4] nfineon, alulate of m ajor GBT operating parameters, App. Note ANP99E, nfineon Tehnology, Aug [5]. M. Uriarte, A. L. GattoZZi, J. D. Herbst, H. B. Estes, T. J. Hotz, A. Kwasinski, R. E. Hebner, A D Ar Model for Series aults in Low olta Mirogrids, EEE Trans. Smart Grid., ol., No. 4, pp. 6-7, De.. [6] Toshiba, GBT, GT6M datasheet, July 4. [7] Toshiba, Photooupler, TLP5 datasheet, Otober 7. E-SSN: 4-5X 68 olume, 7

Speed Regulation of a Small BLDC Motor using Genetic-Based Proportional Control

World Aademy of Siene, Engineering and Tehnology 47 8 Speed Regulation of a Small BLDC Motor using Geneti-Based Proportional Control S. Poonsawat, and T. Kulworawanihpong Abstrat This paper presents the