Wold Electic Vehicle Jounal Vol. 4 - ISSN 03-6653 - 00 WEVA Page000505 EVS5 Shenzhen, hina, Nov 5-9, 00 A Multi-hybid Enegy Sytem fo Hybid Electic Vehicle Xiaodong Zhang, K. T. hau, and.. han Depatment of Electical and Electonic Engineeing, the Univeity of Hong Kong Hong Kong Special Adminitation Region, hina xiaodong@eee.hku.hk Abtact Recently the themoelectic-photovoltaic (TE-PV) hybid enegy ytem fo hybid electic vehicle ha been popoed. Howeve, the output voltage of thi TE-PV hybid enegy ytem i govened by the voltage of the battey, which i affected by the tate of chage of the battey and the chaging/dichaging cuent. Futhemoe, in ode to impove the powe denity and life cycle of the battey, the ultacapacito (U) ha been popoed to hybidize with the battey to fom a hybid enegy toage ytem. In thi pape, a multi-hybid enegy ytem i popoed fo HEV, which incopoate the advantage of the TE-PV hybid ubytem and the ultacapacito-battey (U-B) hybid ubytem. On the one ide, the TE-PV hybid ubytem can povide the highe fuel economy due to the inceae of on-boad enewable enegy, the bette enegy ecuity due to the ue of multiple enegy ouce, and the highe contol flexibility due to the coodination fo chaging the ame pack of batteie. On the othe ide, the U-B hybid ubytem can povide fate tanient powe, highe powe denity and longe battey lifetime. Detailed imulation eult ae given to highlight the effectivene of the deigned multi-hybid enegy ytem. Keywod: Hybid electic vehicle, hybid enegy ytem, themoelectic, photovoltaic, multiple input convete Intoduction In ecent yea, thee ha been active eeach on exhaut ga wate heat enegy ecovey fo hybid electic vehicle (HEV) []-[4]. Meanwhile, the ue of ola enegy i alo popoed to pomote on-boad enewable enegy and hence to impove thei fuel economy [5]-[6]. Thee kind of enegy ouce can be ued to online feed vaiou automotive electonic o chage the battey fo toage, hence educing the oil conumption and the cabon emiion of the automobile. Benefited fom the photovoltaic effect and the Seebeck effect epectively, the photovoltaic (PV) panel and themoelectic (TE) module can diectly convet the ola enegy and heat enegy to electical enegy [7]. A a elatively matue technology, the PV geneato (PVG) ha aleady been wildly employed in many field and in many yea, while the TE geneato (TEG) ha moe etaint only fo the application with ufficient heat ouce o wate heat ouce. Howeve, the TEG ha unique advantage of being maintenance fee, ilent in opeation, independent on weathe o topogaphy and involving no moving and complex EVS5 Wold Battey, Hybid and Fuel ell Electic Vehicle Sympoium
Wold Electic Vehicle Jounal Vol. 4 - ISSN 03-6653 - 00 WEVA Page000506 mechanical pat, compaed with othe powe geneato like gaoline moto-geneato, hydopowe geneato and wind tubine [8]-[3]. In the pat yea, many application have been epoted on the TEG, whee the PVG can alo been applied. The concept of enegy hybidization ha been accepted fo HEV [4]. ompaed with individual enegy ouce, the hybid enegy ytem can offe ome definite advantage fo automobile, namely the highe fuel economy due to the inceae of on-boad enewable enegy, the bette enegy ecuity due to the ue of multiple eouce, and the highe contol flexibility due to the coodination fo chaging the ame pack of batteie [5]. A numbe of topologie of powe conditioning cicuit (PS) fo mall cale powe geneato have been popoed in the lat decade [6]-[8]. Howeve, thee topologie can not meet the equiement of the hybid enegy ouce [9], [0]. The multiple-input convete (MI) can be ued to inteface the enegy ouce and the load a the powe conditioning cicuit []. Thi cla of D-D convete can imultaneouly handle multiple input, and egulate the output voltage o cuent. onequently, the themoelectic-photovoltaic (TE-PV) hybid enegy ytem fo HEV ha been popoed []. Thi TE-PV hybid enegy ytem enable both the TEG and PVG imultaneouly achieving the maximum output powe with the deigned powe conditioning cicuit. In thi kind of TE-PV hybid enegy ytem, a battey i connected with the load in paallel to maintain table output voltage and eve a the enegy toage device. onequently, the output voltage of thi TE-PV hybid enegy ytem i govened by the voltage of the battey, which i affected by the tate of chage of the battey and the chaging/dichaging cuent [3]. On the othe hand, in ode to impove the powe denity and life cycle of the battey, the ultacapacito (U) ha been popoed to hybidize with the battey to fom a hybid enegy ouce [4]. Few algoithm fo the powe aignment between the battey and U have been epoted [5]. The low-pa filte contol tategy can enue that the tanient cuent demand i poceed by the U uing a low-pa filte, which tabilize the output powe of the battey and potentially extend it life time [6]-[7]. In thi pape, a multi-hybid enegy ytem i popoed fo HEV, which incopoate the advantage of the TE-PV hybid ubytem and the ultacapacito-battey (U-B) hybid ubytem. On the one ide, the TE-PV hybid ubytem can povide the highe fuel economy, bette enegy ecuity, and highe contol flexibility. On the othe ide, the U-B hybid ubytem can povide fate tanient powe, highe powe denity and longe battey lifetime. Simulation eult ae given to how the pefomance and illutate the meit of the popoed multi-hybid enegy ytem. Multi-hybid Enegy Sytem The popoed powe conditioning cicuit i hown in Figue. The TE-PV ubytem i ealized by a Ćuk-Ćuk MI, while the U-B ubytem i by a bidiectional buck-buck MI. TEG TE V TE PVG PV V PV L S L S D D L R load S 3 S 3 D 3 S 4 S 4 D 3 D 4 D 4 L 3 L 3 U Figue : Popoed multi-hybid enegy ytem.. TE-PV Subytem The Ćuk-Ćuk MI i elected fo powe conditioning of the TEG and PVG, which function to tack the maximum powe point of the TEG o PVG. Fit, the output voltage of the TEG o PVG may widely and dynamically vay with extenal phyical facto. The Ćuk convete having both tep-up and tep-down chaacteitic can handle a wide ange of input voltage vaiation caued by diffeent tempeatue diffeence and inolation level. Second, when the witch i tuned off, the Ćuk convete can inheently block the D input fom the TEG o PVG enegy ouce to the load due to the exitence of the intemediate capacito. Thid, both of the input cuent and output cuent of the Ćuk cicuit ae non-pulating. By popely winding the input and output inducto on the ame coe, the ipple amplitude can be educed to zeo. Thi meit can B EVS5 Wold Battey, Hybid and Fuel ell Electic Vehicle Sympoium
Wold Electic Vehicle Jounal Vol. 4 - ISSN 03-6653 - 00 WEVA Page000507 ignificantly minimize the ditubance on the TEG o PVG opeating point, and potentially enhance the battey life. The Ćuk convete can be opeated in thee mode: continuou cuent mode (M), dicontinuou inducto cuent mode (DIM), and dicontinuou capacito voltage mode (DVM). Geneally, the M i moe uitable fo high voltage, high cuent input application; the DIM i fo high voltage, low cuent input application; and the DVM i fo low voltage, high cuent input application. Since the TEG and PVG ae of low output voltage, hence low input voltage fo the Ćuk-Ćuk MI, it i pefeed to opeate in the DVM mode. The input eitance of the Ćuk-Ćuk MI in the DVM mode ae impeed a following [6]: T TE = ( D ) () T PV = ( D) () whee T i the witching peiod, D and D ae the duty cycle of the witch S and S, epaately. By tuning the duty cycle of the PWM witching ignal to enable the input eitance equal to the intenal eitance of the enegy ouce, the maximum powe point tacking (MPPT) can be pefomed. The hill climbing method i ued fo MPPT, which i baed on the fact that only one maximum powe point (MPP) of the TEG and PVG exit in the pecific cicumtance. If the dp / dv i poitive, it mean the opeating point i on the left ide of the MPP. Then, the duty cycle hould be deduced accoding to () and (). On the contay, if the dp / dv i negative, the opeating point i on the ight ide of the MPP. Then, the duty cycle hould be inceaed. Until dp / dv equal zeo, the opeating point i on the MPP. The algoithm of the hill climbing method i witten a: D k+ = D k gn( Δ P * Δ V ) Δ D (3) whee D i i the witching ignal duty cycle, Δ P = P k P k, and Δ V = V k V k ae the input powe and voltage diffeence at the ampling intant i, epectively, and Δ D i initialized a 0.%, i =,, L k, k, k +, L. The MPPT diagam i hown in Figue. V in Iin Z Z ΔD Figue : MPPT diagam.. U-B Subytem The paalleled bidiectional buck convete i ued to inteface the toage device with the D bu. If the bu voltage i highe than the peetting voltage level, the witche S 3 and S 3 ae contolled to chaging the battey and U. While the bu voltage i lowe than the peetting voltage level, the witche S 3 and S 3 ae contolled to dichaging the battey and U. The powe balance contol diagam i illutated in Figue 3. * U U load U cuent Battey cuent.0 0.8 0.6 0.4 0. 0.0.0 0.8 0.6 0.4 0. Ue Ief τ + τ + I U I Uef I Bef I B Z D U D B Figue 3: Powe balance contol diagam. 0.0 0.0 0.05 0.05 0. 0. τ = τ = 0.0 0.0 0. 0.4 0.6 0.8.0 Time () Figue 4: Low-pa filte at diffeent time contant. Since the U can be apidly chaged o dichaged, it i ued to povide tanient cuent to lowe the changing ate of the battey cuent. The cuent ditibution between the battey and U i contolled by low-pa filte, which i given by: 0.5 0.5 D EVS5 Wold Battey, Hybid and Fuel ell Electic Vehicle Sympoium 3
Wold Electic Vehicle Jounal Vol. 4 - ISSN 03-6653 - 00 WEVA Page000508 I I Uef Bef = I = I ef ef ( ) τ + τ + (4) (5) whee τ i the time contant. Given a unit tep input, the output of the low-pa filte i hown in Figue 4. tanient ae ecoded at inducto L 3 and L 3, which ae denoted a U banch and Battey banch, epectively. 3 Simulation Reult The multi-hybid enegy ytem i imulated in Matlab/Simulink with the paamete hown in Table. Table : Simulation paamete. (a) Name Value Unit V TE 34.64 V TE 6 Ω V PV 8.44 V PV 3.37 Ω 0.67 uf 0.655 uf T 0.0 m L, L 550 uh L 300 uh L 3, L 3 0 uh τ 0.04 - V B V U. F 000 uf R load.6 Ω Fom Fig. 5, it can be found that the maximum powe point of the TEG and PVG ae tacked imultaneouly by tuning the duty cycle of the diving ignal of the TE-PV Ćuk-Ćuk MI. When a udden load i applied, the U banch will be dichaged to povide the tanient powe and educe the impact to the battey by tuning the diving ignal of the U-B D-D MI, a hown in Fig. 6. The coeponding cuent (b) Figue 5: MPPT of TE-PV ubytem. (a), Duty cycle v. time. (b), Powe v. time. 4 oncluion In thi pape, a multi-hybid enegy ytem i popoed and implemented fo HEV, which combine the TEG and PVG hybid ubytem, U and battey hybid ubytem. It offe the advantage of both the TE-PV hybid ubytem and the U-B hybid ubytem. ompaed with the peviou TE-PV enegy ytem, the popoed multi-hybid ytem can daw the maximum powe fom the TEG and PVG, and offe table output bu voltage. With MPPT and powe balance contol, the meit and pefomance of the popoed ytem ae imulated. EVS5 Wold Battey, Hybid and Fuel ell Electic Vehicle Sympoium 4
Wold Electic Vehicle Jounal Vol. 4 - ISSN 03-6653 - 00 WEVA Page000509 (a) (b) Figue 6: Powe balance of U-B ubytem. (a), Duty cycle v. time. (b), uent v. time. Acknowledgment Thi wok wa uppoted by a gant (Poject code: 008077603) fom the ommittee on Reeach and onfeence Gant, The Univeity of Hong Kong, Hong Kong Special Adminitative Region, hina. Refeence [].. han and K. T. hau, An oveview of powe electonic in electic vehicle, IEEE Tanaction on Indutial Electonic, Vol. 44, No., Feb. 997, pp. 3-3. [].. han, The tate of the at of the electic, hybid, and fuel cell vehicle, Poceeding of the IEEE, Vol. 95, No. 4, pp. 704-78, Ap. 007. [3]. Yu, K. T. hau and.. han, Themoelectic wate heat enegy ecovey fo hybid electic vehicle, Poceeding of 3d Intenational Electic Vehicle Sympoium, Dec. 007, Pape No.. [4] K. T. hau, Y. S. Wong and.. han, An oveview of enegy ouce fo electic vehicle, Enegy onveion and Management, Vol. 40, No. 0, pp. 0-039, July 999. [5] K. T. hau and Y. S. Wong, Hybidization of enegy ouce in electic vehicle, Enegy onveion and Management, Vol. 4, No. 9, pp. 059-069, June 00. [6] X. Zhang and K. T. hau, An automotive themoelectic-photovoltaic hybid enegy ytem uing maximum powe point tacking, Enegy onveion and Management, Vol. 5, No., pp. 64-647, Jan. 0. [7] S. Niu, K. T. hau and J. Z. Jiang, Analyi of eddy-cuent lo in a double-tato cupoto PM machine, IEEE Tanaction on Magnetic., Vol. 44, No., pp. 440-4404, Nov. 008. [8] S. Niu, K. T. hau, J. Z. Jiang and. Liu, Deign and contol of a new double-tato cup-oto pemanent-magnet machine fo wind powe geneation, IEEE Tanaction on Magnetic, Vol. 43, No. 6, pp. 50-503, June 007. [9]. Liu, K. T. hau and X. Zhang, An efficient wind-photovoltaic hybid geneation ytem Uing doubly-excited pemanentmagnet buhle machine, IEEE Tanaction on Indutial Electonic, Vol. 57, No. 3, pp. 83-839, Ma. 00. [0] S. Niu, K.T. hau and. Yu, Quantitative compaion of double-tato and taditional pemanent magnet buhle machine, AIP Jounal of Applied Phyic, Vol. 05, No. 7, Feb. 009, Pape No. 07F05. [] X. Zhang and K. T. hau, Deign and implementation of a new themoelecticphotovoltaic hybid enegy ytem fo hybid electic vehicle, Electic Powe omponent and Sytem, Vol. 39, No. 6, pp. 5-55, Ap. 0. [] S. Niu, K. T. hau, J. Li and W. Li, Eddycuent analyi of double-tato inet-type pemanent magnet buhle machine, IEEE Tanaction on Applied Supeconductivity, Vol. 0, No. 3, pp. 097-0, Oct.009. [3] Y. Fan, K. T. hau and S. Niu, Development of a new buhle doubly fed doubly alient machine fo wind powe geneation, IEEE Tanaction on Magnetic, Vol. 4, No. 0, pp. 3455-3457, Oct. 006. EVS5 Wold Battey, Hybid and Fuel ell Electic Vehicle Sympoium 5
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