Available online at www.sciencediect.com ScienceDiect Enegy Pocedia 88 (2016 ) 662 667 CUE2015-Applied Enegy Symposium and Summit 2015: Low cabon cities and uban enegy systems Diagnosis method of adiated emission fom battey management system fo electic vehicle Xinjie Gao a, Donglin Su a, Li Zhai b, *, Xinyu Zhang b a Beihang Univesity, Xueyuan Steet NO.37, Haidian Distict, Beijing 100083, China b Beijing Institute of Technology, Zhongguancun South Steet NO.5, Haidian Distict, Beijing 100081, China Abstact Electomagnetic emission fom EVs has an effect on boad equipment and neaby vehicles in uban tanspotation. Moeove, the electomagnetic emission fom BMS in EVs can exceed the CISPR 12 limits of adiated emission fo EVs. The adiated electic fields aveage fo an electic ca (CISPR12) is measued in semi-anechoic chambe (SAC) at a distance of 10m to study the diagnosis method fo EMI. An exclusion pocedue fo EMI fom BMS is designed to detemine the component esponsible fo emission peaks though fa-field antenna testing fo vehicle. BMS and instument ae esponsible fo the aveage adiated emission exceeded the limits fo the testing EV. The nea-field testing is used to diagnose the location of EMI. Fom measuements and analysis of EMI fom clock, the clock oscillato is the key component esponsible fo naowband emission, and powe devices switching in DC-DC convete BMS is the key component esponsible fo boadband emission. 2016 Published by Elsevie Ltd. This is an open access aticle unde the CC BY-NC-ND license 2015 The Authos. Published by Elsevie Ltd. (http://ceativecommons.og/licenses/by-nc-nd/4.0/). Selection and/o pee-eview unde esponsibility of CUE Pee-eview unde esponsibility of the oganizing committee of CUE 2015 Keywods: diagnosis method, electomagnetic intefeence, adiated emission, battey management system (BMS), electic vehicle Nomenclatue EVs electic vehicles * Coesponding autho. Tel.: +86-135-2288-5040 E-mail addess: zhaili26@bit.edu.cn. 1876-6102 2016 Published by Elsevie Ltd. This is an open access aticle unde the CC BY-NC-ND license (http://ceativecommons.og/licenses/by-nc-nd/4.0/). Pee-eview unde esponsibility of the oganizing committee of CUE 2015 doi:10.1016/j.egypo.2016.06.095
Xinjie Gao et al. / Enegy Pocedia 88 ( 2016 ) 662 667 663 EMI VCU BMS MCU RMS PWM electomagnetic intefeence vehicle contolle battey management system moto contolle emote teminal pulse width modulation 1. Intoduction The limits in CISPR12 fo vehicle in uban tanspotation ae designed to povide potection fo boadcast eceives in the fequency ange of 30MHz to 1000MHz when used in the esidential envionment [1]. Fom the CISPR12 measuement, much moe emission in vetical polaization exceed the aveage limits at no moto in woking condition, in which some high voltage system and low voltage system ae in woking condition, except electical steeing systems, electic vacuum booste system. Not only high voltage components such as MCU can geneate EMI, but also low voltage components such as BMS, RMS, and instument can geneate electomagnetic emission to intefeence aboad equipment and to make adiated emission fo EVs exceed the CISPR 12 limits [2]. Powe devices switching in DC-DC convete of BMS can geneate conducted and adiated emission [3]. The EMI at high-fequency content fom PWM is due to the ise/fall time of the clock pulse of the oscillato in electic contol system. It is a challenge to the design of BMS and othe low voltage components. Diagnosis method is needed to popose to detemine the component esponsible fo emission peaks exceeded the limits. 2. Constuction of electic fields emission measuement The adiated electic fields aveage fo an electic ca (CISPR12) in vetical polaization is measued in semi-anechoic chambe at a distance of 10m, as shown in Fig.1. The vetical emissions of both sides exceed the CISPR 12 limit at A, B, C, and D aea shown in Fig.2. The peak at A is boadband emission at 110.8 MHz.The peak at B occus at 196 MHz. The peaks at C occu at 576 MHz, 600 MHz, and 624 MHz. The peaks at D occu at 720 MHz, 768 MHz, 816 MHz, and 864 MHz. The naowband emissions at 600MHz exceed the CISPR12limit by 10dB. 3. Diagnostic pocedue Fom Fig.1, the vehicle s electonic systems shall be in nomal opeation mode with the vehicle stationay "READY" state, and the moto dive system could not be in woking opeation at N state. The low voltage active open electic equipment consisting of double flashing lights, wipes, adio and fan should be switched by the dive fo testing. In addition, electic units such as vehicle contolle (VCU), battey management system (BMS), and instumentation should be all in woking condition. The high voltage electical equipment compising of moto contolle (MCU), DC/DC convetes, PTC, electic ai conditioning compesso contolle and batteies ae supplied and enabled by low voltage contol.
664 Xinjie Gao et al. / Enegy Pocedia 88 ( 2016 ) 662 667 Fig.1. Measuement platfom Fig. 2. Emission measuements-vetical polaization An exclusion method is used to detemine the component esponsible fo emission peak though fafield testing fo vehicle. Fist of all, the active open electical components ae closed one by one. Howeve the adiated emissions testing esults was not significantly diffeent. Then the possibility of the active open electical components esponsible fo emission peaks ae excluded and estoed to nomal opeation. Secondly, an investigation is made fo the high voltage electic components except fo high-poweed batteies. The MCU's low voltage connecto is disconnected, and the vehicle cannot be "READY". Howeve the emission peak cannot be mitigation. Next, the low voltage contol connectos ae disconnected fom the othe high voltage electic components one by one. Howeve the emission peak still cannot be mitigated. The high voltage electic components except fo battey powe may not lead to adiated emission exceeded the limits and estoed to nomal opeation. Next, check the oientation of EMI fom low-voltage electical components including VCU, BMS, instumentation, and RMS, etc. in "invisible wok". When the connecto of RMS is emoved, the measuement esults ae unchanged. Afte the instument connecto is disconnected, the peak at B point (196MHz) in Figue 2 is emoved, as shown in Fig.4. It can be indicated that the instument ae esponsible fo the peak at 196MHz. Howeve the peak at A, C, and D could not be emoved. Finally, the fuse of powe supply fo BMS is emoved to disconnect the input powe of intenal DC - DC convete of BMS. The testing esults ae shown in Figue 4. The emission peaks at A, C, and D aea disappea. The emission peak at A point disappeas due to no powe supplied to BMS. Howeve naowband emissions at E aea still exist at 111.65 MHz, 127.6 MHz and 143.55 MHz. The clock oscillato and othe high fequency electonic components in BMS ae esponsible fo the emission peaks at C and D aea. We can conclude that BMS and instument ae esponsible fo the aveage adiated
Xinjie Gao et al. / Enegy Pocedia 88 ( 2016 ) 662 667 665 emission exceeded the limits. Howeve thee ae thee peaks at E aea shown in Fig.4, which is potential to exceed the limits. Fig. 3. Emission measuements without instument Fig. 4. Emission measuements without the fuse of BMS 4. Diagnosis method of key intefeence fequency The CISPR 12 adiated emission measuements fo vehicle is a fa field testing, fom which the poblematic fequencies can be obtained. Howeve it is had to detemine the exact location of EMI fom the components by antennas. The nea-field testing can be used to find the location of EMI. A spectum analyze and a nea-field scanning pobe can be used to test nea electic field o magnetic field to diagnose EMI fom the instument shown in Fig.5. The fundamental fequency of the scanning is 28 MHz shown in Fig.6, which is the fequency of the clock oscillato. The poblematic fequency 196 MHz at B point is 7th hamonics of 28MHz. Fig.5. Nea-field scanning test fo instument
666 Xinjie Gao et al. / Enegy Pocedia 88 ( 2016 ) 662 667 Fig. 6. Nea-field scanning esults fo instument We use the nea-field method to scan the cable connecto of BMS installed in vehicle chassis. The fundamental fequency of the scanning is 24 MHz, which is the fequency of the clock oscillato of electic contol unit fo BMS. The limits ae exceeded at 576 MHz, 600 MHz, and 624 MHz, 720 MHz, 768 MHz, 816 MHz, and 864 MHz due to the fundamental fequency 24 MHz. Fom Fig.4, the fequency diffeence between two peaks at E aea is 15.95 MHz due to the fequency of the clock oscillato of electic unit fo fan, shown in Fig.7. The emission peaks at E aea ae emoved afte the cable connecto of fan is disconnected. 5. Analysis of EMI fom clock Fig. 7. Nea-field scanning esults fo fan Clock wavefom is epesented as peiodic tapezoid-shaped pulses. The key paametes that contibute to the high-fequency spectal content of the wavefom ae the ise and fall times τ, τf of the pulse [4]. A continuous envelope of clock wavefoms is given as sin( ) sin( ) Envelope f f 2A (1) T f f Whee T is the peiod of the wavefom. Aτ/T is dc tem o level. f m, m 1,2,3,..., Fom (1), the bounds fo this spectum is expessed as sin( f ) 20log 10(envelope) 20log 10(2 A ) 20log 10( ) T f sin( f ) 20log 10( ) f (2) Fom (2), the fist beakpoint in the spectal bound is elated to the pulse width 1/πτ. And the second beakpoint is due to1/πτ. Then the high-fequency content is due pimaily to the ise o fall time of the pulse which causes the poduct inability to meet the equiements on adiated emissions. The lowfequency content is due to pulse width and Aτ/T and 1/πτ.
Xinjie Gao et al. / Enegy Pocedia 88 ( 2016 ) 662 667 667 The naowband emission peaks at B, C, D, and E aea exceed the CISPR 12 limits due to the ise and fall time of the clock pulse of electic contol system in BMS, instument and fan. The boadband emission peaks at A is due to the pulse width of the pulse of PWM signals geneated fom DC-DC in powe supply of BMS. 6. Conclusion An exclusion pocedue fo EMI fom BMS is designed to detemine the component esponsible fo emission peaks though fa-field antenna testing and nea-field scanning fo vehicle. Fom measuements and analysis of EMI fom clock, the clock oscillato is the key component esponsible fo naowband emission, and powe devices switching in DC-DC convete of BMS is the key component esponsible fo boadband emission. Acknowledgements This wok was suppoted by the National Natual Science Foundation of China fo financially suppoting this poject (51475045). Refeences [1] CISPR 12, Ed.6.0, Vehicles, boats and intenal combustion engines Radio distubance chaacteistics Limits and methods of measuement fo the potection of off-boad eceives, 2009. [2] N. Mutoh, M. Nakanishi, M. Kanesaki, and J. Nakashima EMI noise contol methods suitable fo electic vehicle dive systems, IEEE Tansactions on Electomagnetic Compatibility, 2005;4:930-936. [3] N. Bondaenko, L. Zhai, B. Xu, G. Li, T. Makhaashvili, D. Loken, P. Bege, T. P. V. Doen, and D. G. Beetne, A measuement-based model of the electomagnetic emissions fom a powe invete, IEEE Tansactions on powe electonics, 2015;30: 5522-5531. [4] C. R. Paul. Intoduction to Electomagnetic Compatibility. 2th ed. New Yok: a john wiley & sons, inc; 2006. Biogaphy Li Zhai has been an Associate Pofesso in Beijing Institute of Technology since 2009. Fom 2013 to 2014, she was a Visito Schola with the EMC Laboatoy, Missoui Univesity of Science and Technology. He eseach inteests include EMC/EMI of powe electonics in EVs, and electical machine contol.