MARMARA ÜNİVERSİTESİ TEKNOLOJİ FAKÜLTESİ Elektromanyetik Uygunluk/Uyumluluk -EMC- Abdullah DEMİR, Yrd. Doç. Dr.
Automotive Systems Past and Present Today s vehicles contain three centuries of technology 19 th century internal combustion engines combined with 20 th century electrical systems and 21 st century electronics. Automotive EMC... from Spark to Satellite
Variety of Electrical Noises and EMC Noise Laboratory Co., Ltd., EMC Test Systems for Automotive Electronics, 2013
Kia Elektromanyetik Uygunluk/Uyumluluk
Elektromanyetik Uygunluk/Uyumluluk Araçlarda kullanılan elektrikli parçaların ayrıca günlük hayatta kullanılan elektrikli aletlerin (örn. cep telefonu) sayısının artmasıyla birlikte elektromanyetik dalgaların yaydığı radyasyon da arttı. Bu dalgaların araçtaki ekipmanlar üzerinde de olumsuz etkileri vardır. Örneğin ateşleme sisteminden yayılan gürültü müzik sisteminden duyulabilir. Hatta yüksek frekanslı elektromanyetik dalgalar kontrol ünitelerinin ve ABS veya ESP gibi güvenlikle ilgili sistemlerin doğru şekilde çalışmasını engelleyebilir. Dolayısıyla bu tür sorunlarla karşılaşmamak için bir takım tedbirler alınması gerekir. Kia
Elektromanyetik Uygunluk/Uyumluluk İşte bu amaçla uygulanabilecek birkaç farklı yöntem: Örneğin, besleme voltajını kesmek için; besleme hattındaki bir röleye diyot takılması, besleme hattındaki ateşleme bobinine kapasitör takılması, besleme hattındaki bir parçaya rezistör takılması veya bu yöntemlerin bir kombinasyonu. Kia
Elektromanyetik Uygunluk/Uyumluluk Hangi yöntemin uygulanacağı; parazit kaynağına, parazitin türüne ve parazitle tüketici cihaz arasındaki bağlantıya bağlıdır. Kia
Elektromanyetik Uygunluk/Uyumluluk Farklı Parazit Tipleri Gürültünün iletilmesini sağlayan farklı yollar vardır. Birincisi hatların ve yalıtkanların doğrudan bağlanmasıdır (galvanik bağlantı). İkinci yol kapasitörlü bağlantı olarak adlandırılır, bu yöntemde kaynak ile gürültünün alıcısı arasında doğrudan bağlantı yoktur. Gürültü, ilgili elektrik alanlarındaki değişimlerle aktarılır. Üçüncüsü, endüktif bağlantıdır. Endüktif bağlantıda, gürültü aktarımı gürültüyü alıcı devreye taşıyan manyetik alanlar vasıtasıyla olur. Kapasitörlü bağlantıda olduğu gibi bunda da doğrudan bağlantı yoktur. Bir diğer gürültü aktarım yolu ise radyasyondur. Bu tür aktarımda elektromanyetik dalgalar hava yoluyla iletilir ve anten görevi gören bir eleman yardımıyla toplanır. Örnek olarak müzik sistemi gösterilmiş ve kullanılmış olsa da, aynı durumun kontrol devreleri için de geçerli olduğunu unutmayın. Kia
Elektromanyetik Uygunluk/Uyumluluk Kia
TEMEL KAVRAMLAR Bağışıklık: Donanımın elektromanyetik bir bozulma bulunduğu sırada performans kaybı olmaksızın tasarlandığı şekilde çalışabilmesini ifade eder. Cihaz: Nihaî kullanıcı için tasarlanmış ve elektromanyetik bozulma oluşturması veya performansı bozulmadan etkilenmesi muhtemel tek bir işlevsel birim olarak satışa sunulan kullanıma hazır herhangi bir tertibatı veya bu tertibatların bir kombinasyonunu; bu tanıma nihaî kullanıcı tarafından cihaza takılması amaçlanan, elektromanyetik bozulma oluşturması veya performansının bu bozulmadan etkilenmesi muhtemel aksamlar veya alt-bileşenler ile cihaz kombinasyonu olarak tanımlanan ve duruma göre hareketli tesisatlar ve belli yerlerde hareket etmesi ve çalışması amaçlanan cihazların da dahil olduğunu ifade eder. Donanım: Herhangi bir cihaz veya sabit tesisatı ifade eder. Elekromanyetik bozulma: Donanımın performansını düşürebilen elektromanyetik gürültü, istenmeyen bir sinyal veya yayılma ortamının kendisindeki bir değişikliği ifade eder. Elektromanyetik ortam: Belli bir yerde gözlenebilen bütün elektromanyetik olayları ifade eder. Elektromanyetik uyumluluk: Donanımın kendi elektromanyetik ortamında, aynı ortamda bulunan donanımlarda tolere edilemeyen elektromanyetik bozulmaya yol açmaksızın tatminkâr bir şekilde çalışabilme yeteneğini ifade eder. Elektromanyetik Uyumluluk Yönetmeliği (2004/108/AT), Sayı : 26680
Araçlardaki Elektronik Sistemler Anti-lock Braking Systems (ABS) Electronic Stability Program (ESP)/Traction control Adaptive Cruise Control Automatic Distance Regulation Automatic rain sensors Headlamp leveling Automatic headlamp controls Parking aids RKE (Remote Keyless Entry) Tiptronic gearshift mechanisms Navigation systems Automatic speed control systems Night vision systems Electric park brake Elektromanyetik Uygunluk/Uyumluluk
Elektromanyetik Uygunluk/Uyumluluk Elektromanyetik Uyumluluk Kanunu'na göre elektrikli ekipman üreticileri ürünlerinin EMC gerekliliklerini karşıladığını göstermeli ve garanti etmelidir. Bunun amacı şudur: Ekipmanın veya sistemin müsaade edilmeyen seviyelerde radyasyon yaymasını veya parazit yapmasını engellemek ve ürünün çalışmasının dış elektromanyetik alanlar nedeniyle engellenmesini önlemektir. Araçlarda kullanılan elektronik ekipmanlar ve sistemler, EMC (Electromagnetic Compatibility = Elektromanyetik Uygunluk/Uyumluluk) direktifine uygun olmak zorundadır. EMC uygunluğu almış elektronik sistemlerin kendisi bir başka elektronik sistemden etkilenmediği gibi kendisi de bir başka elektronik sistemi etkilemez. Kia Electromagnetic Interference (EMI)
Elektromanyetik Uygunluk/Uyumluluk Otomotiv endüstrisinde EMC konusu, bütün elektronik ve elektromekanik sistemlerin birbirleriyle uyumlu bir şekilde çalışması bakımından büyük önem arzetmektedir. Düşünün ki, trafikte aracınızla seyrettiğiniz bir anda, yol ve yön bulmanızda size büyük kolaylıklar sağlayan navigasyon sisteminin yaydığı elektromanyetik alandan etkilenen koltuğunuz ve direksiyonunuz birden bire konum değiştirmeye başlıyor. Özkan Şahin, Motorlu Araçlarda Elektromanyetik Uyumluluk, Standart dergisi, 46. sayı, 2011
Elektromanyetik Uygunluk/Uyumluluk Bazı araçların kullanıcı el kitaplarında şu tür ifadelere ve dikkat çekmelere rastlanabilmektedir. Araç içerisinde kullanılan cep telefonları aracın elektronik sistemini bozabilir ve bu durum aracın çalışma emniyetini ve sizin can güvenliğinizi tehlikeye sokabilir. Cep telefonları; bir dış antene bağlı değilse, yansıtmasız bir dış antene sahipse ya da yanlış monte edilmişse aracın elektronik sistemini etkileyebilir ve bu nedenle aracın çalışma emniyeti ve sizin güvenliğiniz tehlikeye girebilir. Abdullah Demir, Otohaber
Elektromanyetik Uygunluk/Uyumluluk
Elektromanyetik Uygunluk/Uyumluluk Motorlu araçlarda 72/245/AT, Tarım ve Orman Traktörlerinde 75/322/AT ve İki veya Üç Tekerlekli Motorlu Araçlarda 97/24/AT Yönetmelikleri EMC bakımından zorunlu yönetmeliklerdir. Bunlardan başka ECE R-10 Teknik Düzenlemesi de bu araçların ve araçlarda kullanılacak elektronik aksam (ESA- Electronic Sub-Assembly) veya teknik ünitelerin tip onaylarına esas bir mevzuattır. Bu mevzuatlarda araçlar ve ESA lar için tip onay işlemleri anlatılmaktadır. Onay başvurusu, işaretleme şartları, tip tanımları, testlerin yapılış şekilleri ve kabul kriterleri, muafiyetler, kapsam genişletme ve üretimin uygunluğu değerlendirmeleri için metotlar vb. belirtilmektedir. Özkan Şahin, Motorlu Araçlarda Elektromanyetik Uyumluluk, Standart dergisi, 46. sayı, 2011
Elektromanyetik Uygunluk/Uyumluluk Araçlar; Genişband Emisyon Testi, Darband Emisyon Testi ve Elektromanyetik Bağışıklık Testlerine tabi tutulmaktadır. 72/245/AT Yönetmeliği ve ECE R 10-03 Teknik Düzenlemesinde elektromanyetik bağışıklık testleri 20-2000 MHz aralığında 30 V/m şiddetinde elektrik alan uygulayarak yapılmakta ve aracın hızında, vitesinde, sileceklerinde, farlarında, sinyal çalışma frekansında, ayarlanabilir süspansiyon sisteminde, alarmında, kornasında, sürücü koltuğu ve direksiyonun konumunda, hava yastığı ve diğer güvenlik sistemlerinde, otomatik kapılarda ve fren sistemlerinde herhangi bir istenmeyen etki olup olmadığı kontrol edilmektedir. ECE R 10-04 / InterRegs Ltd 2013 Vehicle Immunity Type Approval Limits If tests are made using the method described in Annex 6, the field strength shall be 30V/m/rms (root mean squared) in over 90% of the 20 to 2,000 MHz frequency band and a minimum of 25V/m/rms over the whole 20 to 2,000 MHz frequency band. Özkan Şahin, Motorlu Araçlarda Elektromanyetik Uyumluluk, Standart dergisi, 46. sayı, 2011
Elektromanyetik Uygunluk/Uyumluluk ESA lar için Testler: ESA lar; araçlar için yapılan genişband emisyon, darband emisyon ve elektromanyetik bağışıklık testlerine ilave olarak, aracın elektrik donanımına kablolama yoluyla bağlı olduğundan, iletilen (conducted) emisyon ve iletilen bağışıklık testlerine de tabi tutulması gerekir. anechoic room: Yankısız/Ekosuz oda Mobile phones Power lines Radar transmitters Radio transmitters
Elektromanyetik Uygunluk/Uyumluluk Testi Automotive EMC testing requirements can be separated into two distinctive categories, full vehicle or component levels. The full vehicle testing requirements are most commonly practiced by major automakers, while the component level testing requirements are applied primarily by suppliers of electronic parts contracted by the automakers. Most automotive testing requirements are defined and issued by regional organizations, i.e. European Union (EC) and American (SAE), international (CISPR, IEC and ISO), and manufacturers (GM, Ford, VW, etc.). CISPR, Comité International Spécial des Perturbations Radioélectriques French / Special International Committee on Radio Interference) IEC: International Electrotechnical Commission Figure: One of four General Motors' Milford full vehicle EMC test chambers. (Image courtesy of ETS-Lindgren.) http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Major EMC Standards for Automotive Electronics Noise Laboratory Co., Ltd., EMC Test Systems for Automotive Electronics, 2013
Elektromanyetik Uygunluk/Uyumluluk Testi Among the standards shown in Table 1, recent development activities have focused on automatic EMC testing in the ISO, CISPR, and IEC standard bodies more than the other regional bodies. These standard bodies are focused on EMC issues on electric vehicles and/or fossil fuel electric hybrid vehicles. The ISO-series of test standards are focused on the immunity issues while the CISPRseries test standards are focused on the emission limits on these vehicles at charging modes. Also noted is that the European communities are faster in developing test standards addressing the advent of the EMC problems presented by the electric vehicles and by their operating environment. http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi Full vehicle EMC test facilities are normally built by major automakers and government agencies around the world. Figure 1 shows one of the General Motors full vehicle EMC test chambers with most of the vehicle electromagnetic immunity test setups released. The EC directive and some manufacturers internal standards also require that the vehicle s Electromagnetic Immunity (Susceptibility, EMS) be tested at simulated motion speed(s) and at braking mode. This will require that the full vehicle EMC test chamber be equipped with a chassis dynamometer turntable. EMI: Electromagnetic Immunity EMS: Electromagnetic Susceptibility: elektromanyetik duyarlılık Figure 1: One of four General Motors' Milford full vehicle EMC test chambers. (Image courtesy of ETS-Lindgren.) http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi As shown in Figure 2, the chassis dynamometer and its driving system will add to a substantial amount of complexity of the overall facility construction. In addition, to accommodate the required EMC testing on electrical and/or hybrid vehicles, the charging station and its interfaces to vehicle at charging mode will be needed to complete the full vehicle test capability. The full vehicle test chambers and its test instrumentation are most frequently used for EMS testing, especially the safety features of the vehicles at most known test conditions. Therefore, efficiency in test setups for EMS test is often the most critical utilization factors of the test facility. Electromagnetic Immunity (Susceptibility, EMS) Susceptibility: Duyarlılık, hassasiyet Figure 2 Chassis dynamometer turntable (a) and its support filtered AC/DC power system (b). (Image courtesy of ETS-Lindgren.) http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi The component test chambers are also often called Absorber Lined Shielded Enclosures (ALSE) and a detailed definition of ALSE dimensions and absorber treatment requirements can also be found in the references. 4,5,6 To incorporate the EMC test capability on the electric motor/generator module of the electric/hybrid vehicle, a shielded drive shaft will be needed to provide the drive/load simulation for testing the EMC of the control unit in the motor generator module. The shielded shaft must be designed to transfer and withstand the maximum torque output by the electric motor through ALSE As shown in Figure 3, the ALSE room is generally setup for near-field test distance at 1 m separation between the antenna and the EUT interface cables. EUT (Equipment Under Test) Figure 3 Simplified component level ALSE test chamber with drive/load simulator interface. http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi The ALSE specifications for the absorber treatment only start at 80 MHz and above. The specification assumes that the near-field coupling dominates the overall energy transfer between the test antenna and the test object in the frequency range below 80 MHz. However, a simple electric field dipole coupling model analysis presented by Liu 7 shows a different result. Figure 4a presents the ratio of the total amount of transferred energy to the energy from the radiating component of two electrically small dipoles at 1 m separation distance. As presented, the nearfield coupling overwhelmingly dominates the energy transfer for test frequencies below 20 MHz (greater than 10 db). Above 200 MHz, the radiating far-field component dominates the energy ratio (by more than 10 db since the ratio shows <-10 db). To examine the transition frequency range between 20 and 200 MHz, a ratio of reactive energy to the radiating components demonstrates an alternating variation of radiating energy in this frequency range with a peak at 50 MHz. Again, at above 100 MHz, the near-field coupling diminishes to an insignificant amount. Figure 4 Total electric field vs. tangential and radial components. http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi Figure 4 (a and b) illustrates the importance of good ALSE boundary conditions in the overall measurement uncertainty component EMC testing in an ALSE in the frequency range of 20 to 200 MHz. Since most of the electric inverters and converters for electric and/or hybrid vehicles operate in lower MHz frequency range, a good ALSE room that provides good termination conditions of the shielded wall can be very important for improving the measurement uncertainty and the repeatability of the test results. Thus, an ALSE treated with ferrite tilebased hybrid absorbers can be a preferred choice for automotive component test chambers, especially for testing such vehicles components between 20 to 80 MHz. Figure 4 Total electric field vs. tangential and radial components. http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi In addition to ALSE and anechoic chambers, reverberation chambers have also been introduced for automotive EMC testing. The reverberation chambers, test method has been adopted into SAE J1113-27 and the IEC 61000-4- 21:2011. The most common use of reverberation chambers is for radiated immunity testing because the reverberation chambers are capable of generating high field intensity level requiring much lower amplifier power than that of free space test setup. A well-built reverberation chamber is capable of generating > 25 V/m using just 1 W of drive power at the antenna port at prior to EUT loading. Large test volume of up to 8 percent total space of the chamber can also be achieved through the introduction of one or more stirrers. Figure 5 shows typical configuration of automotive EMC testing utilizing reverberation methods for both component and full vehicle radiated immunity testing. Typical constructions of reverberation chambers are for testing frequencies above 80 MHz to be efficient in both cost and building space utilization. Figure 5 Component (a) and full vehicle reverb test chambers (b). (Image courtesy of ETS-Lindgren.) Reverberation: yansıma/yankılama http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi Figure 5 Component (a) and full vehicle reverb test chambers (b). (Image courtesy of ETS-Lindgren.) http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Elektronik Aksam (ESA- Electronic Sub Assembly) Şekil-1: Yönetmeliğin ESA lara uygulanış şekli. Özkan Şahin, Motorlu Araçlarda Elektromanyetik Uyumluluk, Standart dergisi, 46. sayı, 2011
Elektromanyetik Uygunluk/Uyumluluk OKUMA PARÇASI: Bağışıklıkla ilgili Fonksiyonlar: (a) Aracın doğrudan kumandası ile ilgili fonksiyonlar: Örneğin; motor, şanzıman, fren, süspansiyon, aktif yönlendirme, hız sınırlayıcı tertibatın özelliklerinde bozulma ya da değişiklik. Örneğin, koltuk veya direksiyon simidi konumunun ayarlanması sonucunda sürücünün konumunun etkilenmesi. Örneğin, kısa huzme veya ön cam sileceğinin kullanımı sonucunda sürücünün görüşünün etkilenmesi. (b) Sürücü, yolcu veya diğer yol kullanıcıların korunmasıyla ilgili fonksiyonlar: Hava yastığı, emniyet bağlantı sistemleri gibi. (c) Bozulduğunda sürücünün veya diğer yol kullanıcıların şaşırmasına neden olan fonksiyonlar: Optik bozulmalar: Sinyal lambaları, park lambaları, uç hat işaretleme lambaları, geri vites lambası, acil durum ışıkları ve benzerlerinin yanlış çalışması ile sürücünün doğrudan görüş alanında yer alan ve (a) ve (b) bentlerinde belirtilen işlevlerle ilgili olan ikaz göstergeleri, lambaları veya ekranlarından gelen yanlış bilgiler. Akustik bozulmalar: Örneğin, hırsız alarmı ve kornanın yanlış çalışması. (d) Araç veri yolu sisteminin işlevselliği ile ilgili fonksiyonlar: Bağışıklıkla ilgili diğer fonksiyonların düzgün işleyişini sağlamak için gereken verilerin iletiminde kullanılan araç veri yolu sistemlerinde veri iletiminin engellenmesi ile. (e) Bozulduklarında aracın, takograf ve kilometre saati gibi yasal verilerini etkileyen fonksiyonlar. Özkan Şahin, Motorlu Araçlarda Elektromanyetik Uyumluluk, Standart dergisi, 46. sayı, 2011
Elektromanyetik Uygunluk/Uyumluluk OKUMA PARÇASI: Hangi donanımlarda e hangi donanımlarda CE sembolü aranmalıdır? Sürücünün aracı kullanması üzerine doğrudan etkisi olan hız kontrol sistemi veya elektronik olarak kumanda edilen amortisör sistemlerinde e sembolü (Avrupa Birliği Onay İşareti) bulunmalı ve ilgili aracın üreticisinin de onayı olmalıdır. Ek olarak takılan elektriksel cihazlar ve donanımlar, aracın doğrudan kontrolünü etkilemiyorsa, örneğin buzdolabı, bilgisayar ya da fanlar ise CE sembolünü (Avrupa Topluluğu Üreticileri Mutabakat Açıklaması yani Avrupa ya Uygunluk) taşımalıdır. Özkan Şahin, Motorlu Araçlarda Elektromanyetik Uyumluluk, Standart dergisi, 46. sayı, 2011
Elektromanyetik Uygunluk/Uyumluluk READING TEXT: Widespread use of computer and energy conversion systems present new EMC challenges in modern car design. An efficient EMC test facility can provide fasttrack design validation for faster completion of both component and full vehicle integrity. Just as traffic laws cannot avoid auto accidents, EMC design planning and testing cannot totally eliminate the automotive EMC problems as the electronic systems in the car get more and more complex. However, we can minimize automotive system malfunctions due to EMC problems through our design and testing efforts. Having said that, it does not mean that the cars we drive are not safe because of EMC issues. On the contrary, cars are much safer and much more fuel efficient than before due to the introduction of electronic control systems. Our efforts in automotive EMC are to aid the speedier introduction of more sophisticated computer systems to the car for further improvement in the safety and efficiency of the future vehicles. http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
READING TEXT http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
and can result in EMC issues from LF to SHF! Why is EMC Important to the Automotive Industry? Today s electronic systems (including vehicles) contain many more active electronic components than in the past. Those components and assemblies may emit RF noise or be exposed to external sources of energy -resulting in unanticipated changes in system operation.
The EMC Model (as applied to Automotive Systems) The Source near / far field high magnetic field or electric field? The Path radiated or conducted? The Receiver intentional or unintentional?
Electromagnetic Environment for Automotive Systems May be off board and on board sources. Studies have shown almost DC to daylight sources and high field strength levels both electric and magnetic. Typical on board fields of 10 100 V/m. Some off board fields are 100 s of V/m!
Examples of Off Board RF New wireless technologies demand more spectrum and more energy Many rural areas are now populated Vehicle must operate in this new environment
On Board Vehicle Sources Automobiles can have on board sources of significant emissions. High RF levels with common equipment such as mobile radio transmitters.
Automotive Industry EMC Methodology Vehicle Original Equipment Manufacturer (OEM) practice is to address EMC in the component and system design phase. The resolution of EMC issues must comprehend a high volume, complex manufacturing process AND do not affect program timing. Goal is to balance EMC requirements with market-based vehicle usage.
Customer Focused Automotive EMC Benefit Recognition of two-way radio usage. Important to understand installation in vehicles to minimize EMC issues.
Development of OEM Mobile Radio Installation Guidelines Shows EMC friendly methods to install two way radios and antenna systems. Based on commercially available radios and transmitters.
Automotive EMC Requirements Good News: Most automotive systems are exempt from FCC Part 15 (see 15.103). Bad News: OEM requirements typically 10 to 40 db more stringent than Part 15. Ugly News: Most OEM requirements are based upon international standards such as CISPR, ISO, SAE (which many international legislated requirements are also based on).
Automotive EMC Case Studies Emissions: Microprocessor clock harmonic was on two way radio frequency rendering radio communication impossible. Immunity (the Automotive characterization of susceptibility): An engine and transmission seemed defective due to control system malfunctions cause was a change from a metal to a non-conductive component package.
Automotive System RF Emissions Vehicle systems can be responsible for onboard noise generation as a byproduct of vehicle operation. In the automotive industry, this noise has been classified into two categories: Broadband (typically due to electrical arcing) Referred to as Arc and Spark noise. Narrowband (typically due to active electronics) All other noise NOT due to Arc and Spark.
Representation Of Noise Bandwidth Broadband noise is greater than the width of receiver of the energy. Narrowband noise is less than the width of the receiver. Impact AM Noise FM loss of sensitivity. AM vs FM: AM (or Amplitude Modulation) and FM (or Frequency Modulation) are ways of broadcasting radio signals. Both transmit the information in the form of electromagnetic waves. AM works by modulating (varying) the amplitude of the signal or carrier transmitted according to the information being sent, while the frequency remains constant. This differs from FM technology in which information (sound) is encoded by varying the frequency of the wave and the amplitude is kept constant. Kaynak: http://www.diffen.com/difference/am_vs_fm
Typical Sources Of Broadband Noise Sources include ignition components and similar pulse-type systems. Electric motors (both the traditional and the new brushless ).
EMC / RFI Issues in Power Electronics Important to understand the impact of the slew rate of high power devices. Many are designed for low power dissipation during operation resulting in: Operation at an order of magnitude faster than response of electromechanical devices Causing radiated/conducted emission issues.
Representative ignition systems used today -all utilize high-voltage discharge. Source of noise is spark discharge across gap in plug and/or distributor. Why Ignition Noise Is Broadband
Consequences Of Broadband Noise Sources BAD Due to functions that are required for basic vehicle operation (such as ignition or inductive devices). BAD Can have both conducted AND radiated coupling path. GOOD Energy spread out may have minimal effect on potential receivers (intentional and unintentional).
Representation of Narrowband Emissions Sources are active electronics. Result is a spectrum of a comb-like appearance. Spectrum stays approximately constant over time.
Consequences Of Narrowband Noise Sources BAD -May be many sources on a vehicle due to proliferation of active devices. BAD -Receivers can appear to function almost normal. GOOD -Can be addressed in component design process.
Immunity Issues Must Be Addressed -Why? Complex engine/vehicle control systems require a high degree of robustness to insure proper operation
Vehicle Level Immunity To External Fields The goal: to understand the compatibility of the electronic systems with the environment
Today s Systems Can Have Immunity Issues Characteristics of today s systems are: Electronic modules that radiate energy may also be efficient unintentional receivers of energy. Therefore, RF sources may affect the operation of active devices.with the following implications
Immunity Issues Can Exist Due To The Following Most of today s vehicle rely on active devices, microprocessors, and vehicle communication networks for: Control of vehicle functions. Entertainment systems. Legislated requirements (such as tire pressure monitoring).
Immunity: Industry Practices How to ensure product immunity? -Measures should be implemented to design in appropriate immunity characteristics. -System and component testing can be conducted by simulating external sources to ensure immunity characteristics.
Bulk Current Injection (BCI) Test Method Injection of RF or pulse energy on wiring harness. Typical BCI testing is to 400 MHz. General rule: 1.5 ma of RF current induced on a cable is equivalent to ½ wavelength cable in a field strength of 1 V/M.
EMC Circuit Design for Immunity Add series inductance to sensitive I/O. Add parallel capacitance to shunt RF away. Buffer or isolate circuits (opto-isolator, transformer). Keep circuit gain-bandwidth to minimum required. Application of localized shielding on devices.
Wire Routing Impact On EMC Even the process of wire routing is can be an important contributor to EMC! Need to comprehend sources and receivers in systems. Wire routing affects EMC Path. Critical to recognize that due to parasitic inductance and/or capacitance effects exist.
Why Wiring Is Contributor To Conducted EMC Issues Early vehicle systems had few electrical components to be connected -when many wiring practices were developed. Today s systems have increased wiring demands and sensitive electronic devices. Must be addressed -wiring will still be used for the foreseeable future.
Why Wiring is Important to Automotive EMC Early systems (and vehicles) had few components to be connected -Recent systems have increased wiring complexity. Many automotive engineers consider it just a piece of wire and the chassis is GROUND! Wiring will still be used for many systems in the future. Need to understand relevant physical parameters.
Role Of Wiring In Conducted EMC Issues Energy may escape or be brought into/from the modules by conduction with wiring harness. Wiring can act as a coupling mechanism.
Automotive Wiring Inductive Coupling Coupling from the wiring of system 1 to the wiring of system 2 can occur. May be due to common ground with many automotive circuits. Noise is induced in system 2 by di/dt of system 1: Occurs during period when di/dt NOT equal to zero Is the source of inductively coupled transients
Automotive Wiring Capacitive Coupling Capacitive coupling from system 1 to system 2. Due to close proximity of many wires in a harness bundle. Noise is induced in system 2 by dv/dt of system 1: Occurs during period when dv/dt NOT equal to zero Is the source of capacitive coupled transients
Auto Industry Best Practices For Wiring To Minimize EMC Recommendation Route wiring away from ignition system, spark plug wires, and alternator wiring. Don t bundle antenna, speaker, or power wiring with vehicle wiring Rationale High energy noise may couple inductively or capacitively into wiring Low-level signals can be affected by highpower circuits.
Conducted Transients and Automotive Systems Can result in voltages about 5 10 times that of vehicle system (e.g. 13.8 volts 150 volts transient generation). Can be results of the many inductive loads used in automotive systems.
Protection is Required to Minimize Effect of Transients Circuit provisions for over voltage, load dump, and reverse battery should be made. Transient protection should be on all I/O and lines going to vehicle power. Realize that all vehicle devices may not have extensive transient suppression needed by sensitive I/O.
Automotive EMC Electrostatic Discharge Testing is used to identify sensitivities. Simulates natural and human-body induced high voltage ( 4-25 kv) discharges. Can cause immediate failure or induce latent defect (such as in manufacturing process or customer use).
Things to Consider Before Vehicle Level Testing Begins Meet component requirements. Wiring representative of the actual production vehicle. Why? Component level requirements are set at level to prevent any vehicle level interactions from occurring. Many time only the power and signal lines are in the harness and the return conductor is the vehicle chassis.
Quick Vehicle Level Help For emission diagnostics: AM/FM radio receivers -AM setting useful to trace BB noise -FM useful to trace NB noise. Clamp ferrites on harnesses to eliminate effect of conducted energy. Disconnect fuses until noise stops. For immunity 150 MHz hand held radio can provide local high fields to identify potential issues.
Automotive Component EMC Practices Goal should be to identify options to address EMC early in the design stage. Early attention minimizes cost and maximizes available options. Use Pre-Compliance methods whenever possible
The Component s Role In Automotive EMC Incorporate a Design for EMC approach. Test by simulating component operation as it would function in the complete vehicle. If component passes test no action is required. If it does not pass -use the test data to determine corrective action plans.
Component Testing Methods Most are based upon CISPR, ISO standards (two of which will be discussed in detail by Vince Rodriguez). Defines typical component level test set-up. Device under test is configured to function in a manner similar to vehicle application.
What is the Supplier s Role? Obligation to deliver a component that meets-component level EMC without requiring vehicle level corrective actions. Depends on crucial supplier-to-oem cooperation. Important to know the program requirements and demonstrate compliance by validation.
Component Level EMC Program Plan The process to ensure proper component design, development, and validation prior to vehicle validation. The process includes: Definition of test modes, and input signals similar to application usage. Wiring harness definition. Load definition. Methods for monitoring test results.
Next Steps for Automotive EMC Develop and improve simulation and modeling to include both DESIGN aspects and impact of manufacturing issues. Goal is to develop physics based models and to evaluate anticipated EMC characteristics using circuit simulation and electromagnetic theory. Key aspect is understanding the coupling paths, sources and receivers.
Automotive EMC-Overview Automotive EMC is concerned with vehicle electrical/electronic system interaction. Looks at radiation or conduction. Can be addressed by emphasis in the design stage and verified through testing.
Automotive EMC Summary The first vehicle EMC issues were primarily limited to reception quality of AM radios. Today s vehicles have many complex systems: Powertrain Control Vehicle Control Communication Tomorrow s vehicle will be even more complex: Hybrid s Fuel Cells
Automotive EMC The Future The success of our ability to manage the EMC of future systems will depend on: How we use our knowledge of the fundamental issues that have been discussed here. Our ability to work together using the tools available to us!
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Elektromanyetik Uygunluk/Uyumluluk Testi The component test chambers are also often called Absorber Lined Shielded Enclosures (ALSE) and a detailed definition of ALSE dimensions and absorber treatment requirements can also be found in the references. 4,5,6 To incorporate the EMC test capability on the electric motor/generator module of the electric/hybrid vehicle, a shielded drive shaft will be needed to provide the drive/load simulation for testing the EMC of the control unit in the motor generator module. The shielded shaft must be designed to transfer and withstand the maximum torque output by the electric motor through ALSE As shown in Figure 3, the ALSE room is generally setup for near-field test distance at 1 m separation between the antenna and the EUT interface cables. EUT (Equipment Under Test) Figure 3 Simplified component level ALSE test chamber with drive/load simulator interface. http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi The ALSE specifications for the absorber treatment only start at 80 MHz and above. The specification assumes that the near-field coupling dominates the overall energy transfer between the test antenna and the test object in the frequency range below 80 MHz. However, a simple electric field dipole coupling model analysis presented by Liu 7 shows a different result. Figure 4a presents the ratio of the total amount of transferred energy to the energy from the radiating component of two electrically small dipoles at 1 m separation distance. As presented, the nearfield coupling overwhelmingly dominates the energy transfer for test frequencies below 20 MHz (greater than 10 db). Above 200 MHz, the radiating far-field component dominates the energy ratio (by more than 10 db since the ratio shows <-10 db). To examine the transition frequency range between 20 and 200 MHz, a ratio of reactive energy to the radiating components demonstrates an alternating variation of radiating energy in this frequency range with a peak at 50 MHz. Again, at above 100 MHz, the near-field coupling diminishes to an insignificant amount. Figure 4 Total electric field vs. tangential and radial components. http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi Figure 4 (a and b) illustrates the importance of good ALSE boundary conditions in the overall measurement uncertainty component EMC testing in an ALSE in the frequency range of 20 to 200 MHz. Since most of the electric inverters and converters for electric and/or hybrid vehicles operate in lower MHz frequency range, a good ALSE room that provides good termination conditions of the shielded wall can be very important for improving the measurement uncertainty and the repeatability of the test results. Thus, an ALSE treated with ferrite tilebased hybrid absorbers can be a preferred choice for automotive component test chambers, especially for testing such vehicles components between 20 to 80 MHz. Figure 4 Total electric field vs. tangential and radial components. http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing
Elektromanyetik Uygunluk/Uyumluluk Testi In addition to ALSE and anechoic chambers, reverberation chambers have also been introduced for automotive EMC testing. The reverberation chambers, test method has been adopted into SAE J1113-27 and the IEC 61000-4- 21:2011. The most common use of reverberation chambers is for radiated immunity testing because the reverberation chambers are capable of generating high field intensity level requiring much lower amplifier power than that of free space test setup. A well-built reverberation chamber is capable of generating > 25 V/m using just 1 W of drive power at the antenna port at prior to EUT loading. Large test volume of up to 8 percent total space of the chamber can also be achieved through the introduction of one or more stirrers. Figure 5 shows typical configuration of automotive EMC testing utilizing reverberation methods for both component and full vehicle radiated immunity testing. Typical constructions of reverberation chambers are for testing frequencies above 80 MHz to be efficient in both cost and building space utilization. Figure 5 Component (a) and full vehicle reverb test chambers (b). (Image courtesy of ETS-Lindgren.) Reverberation: yansıma/yankılama http://www.microwavejournal.com/articles/11446-an-update-on-automotive-emc-testing