Automotive emc-compliance


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Automotive emc-compliance

  1. 1. The Ongoing Challenges inAutomotive EMC Compliance Intertek 70 Codman Hill Road Boxborough, MA 01719 800-WORLDLAB
  2. 2. The Ongoing Challenges in Automotive EMC ComplianceContents Introduction ..............................................................................................2 History .......................................................................................................3 The Changing EMC Environment.............................................................3 Changing EMC Test Requirements ..........................................................6 Summary ...................................................................................................7 1
  3. 3. The Ongoing Challenges in Automotive EMC ComplianceIntroductionWith advances in technology over the last decade, customer demand and OEMcompetition has forced automakers to try to integrate many of the latesttechnologies into their vehicles. Many of these technological advances, whetherentertainment, communication or performance improvements, do succeed inbringing to the consumer a new level of comfort and convenience as well asenhanced safety features. But along with these features come new challenges toensure EMC (Electromagnetic Compatibility) and device interoperability within thevehicle. EMC issues can result in minor annoyances such as unwanted noise throughthe entertainment system, as well as major issues such as loss of engine functions orcontrol issues that could compromise the safety of drivers, passengers and thepublic. Add to this the growing demand of Hybrid Electric Vehicles (HEV) andElectric Vehicles (EV). These systems may bring a whole new set of concerns inrelation to EMC. For these reasons, EMC is and will continue to be a very importanttopic of concern for the automakers’ present and future.There are two opposing forces at work influencing EMC in the vehicularenvironment. 1) The growing number of electronic components and modules forcontrol, communications, and entertainment now being installed make achievingEMC far more demanding. 2) The force promising to bring the situation undercontrol is the trend to replace complex vehicle wiring carrying analog, digital, andhigh-current signals with simpler, low-power signaling protocols.Between these two forces, engineers are modifying their predictive tools to keep upwith changes at all levels – integrated circuit EMC evaluation, module EMCprediction and measurement, and whole vehicle characterization. As circuits operateat higher frequencies (and voltages), simulation methods have to adopt smallergrids for the accurate prediction of the resulting electromagnetic fields.As this process of modification is underway, the vehicle manufacturers need toassure that new modules have been tested to their respective EMC standardscorrectly and that the standards reflect the actual environment of future installation.While many vehicle EMC standards are non-governmental (and/or OEM specific)and therefore simpler to update, in the EU the Automotive EMC Directive2004/104/EC contains its own requirements and is therefore more cumbersome toamend. Fortunately, it contains a number of international EMC standard references.With the recent surge of public awareness for a need for alternative vehicles such asEV’s and HEV’s , there are more independent auto manufacturers on the scene andthey are starting to review their own EMC procedures and may see themselvesdeveloping their own standards based on their findings and business growth. 2
  4. 4. The Ongoing Challenges in Automotive EMC ComplianceHistoryThe popularization of the car radio in the late 1920s was the “canary in the coalmine” — the proverbial early warning— that automotive EMC would be anongoing challenge. By the 1930s, a number of commercial radio brands wereavailable. The early models were AM (amplitude modulation) only and verysusceptible to both ignition noise and static buildup from the car’s tires. Bothsources of disturbances were quickly overcome. Spark plug suppression wasprovided by resistive cables and resistive plugs; research on optimum spark plugsuppression continued into the 1970s1. Conductive carbon was added to the cartires to prevent electrostatic charge buildup. In 1947, SAE J551, the first SAE(Society of Automotive Engineers) EMC standard, was published, but it was notuntil the proliferation of vehicular electronics in the 1970s that development offurther vehicle EMC standards occurred.The Changing EMC EnvironmentToday’s motor car contains an amalgam of legacy electrical/electronic functions andmore recent devices – literally dozens of components or modules, sensors andactuators, and more than one network. Table 1 below lists typical functions andtheir attributes. function history attributesAirbag deployment Existing CriticalBraking control Existing Critical Comfort, Radio Noise, gage/warningCabin environment Existing functionCollision avoidance New Likely unlicensed radar 77 GHz.Communications New Cellular, Bluetooth (800, 1900, 2400 GHz)system Environmental and legal concerns in someEmissions control Existing statesEngine ignition Existing Critical May include satellite radio receiver, FMEntertainment system New modulator (low power 88-108 MHz).Fuel injection Existing Critical1 “Relationship Between Spark Plugs and Engine-Radiated Electromagnetic Interference,” IEEETransactions on Electromagnetic Compatibility, Burgett et. al.,August 1974, pp. 160-172. 3
  5. 5. The Ongoing Challenges in Automotive EMC ComplianceLighting system New Some Xenon discharge lamps.Navigation system New GPS receiverNoise cancellation New ComfortSeat and pedal position Existing Critical Short-range and Part 90 radio (170-300Security system Existing MHz)Stability control New CriticalTire pressure New Short-range radiomonitoringTransmission control Existing CriticalTable 1 Typical automotive electronic component or module functions.Each of these functions exists in, and impacts, the vehicle’s EMC environment. Forexample, all of the control systems add to network/bus noise. Also, thecommunications, entertainment and security systems introduce radio sources whilethe GPS (global positioning systems) and satellite radio receivers require very low RFnoise over their operating bands.Compounding these EMC challenges from the added electronic functions are thenew factors associated with Hybrid Electric Vehicles (HEVs) and Electric Vehicles(EVs). Specifically, these include bus voltages exceeding 200 V, power inverterswitching noise, and new bus/cable configurations. These issues are illustrated inthe propulsion system block diagrams in Figure 1 and 2 for HEV and EVconfigurations. 4
  6. 6. The Ongoing Challenges in Automotive EMC Compliance transmission DC AC power High inverter voltage battery DC/DC 12V battery Electric motor Engine Figure 1 Simplified HEV (Hybrid Electric Vehicle) block diagram. DC Electronic High control voltage unit battery 12V battery Power inverters and motors Figure 2 Simplified EV (Electric Vehicle) block diagram.In addition to the basics shown in these figures, there are the myriad modules,sensors, actuators, networks, and central control for the vehicle. 5
  7. 7. The Ongoing Challenges in Automotive EMC ComplianceChanging EMC Test RequirementsExisting EMC whole vehicle and module test standards cover the range ofelectromagnetic phenomena in conventional vehicles2. Vehicle manufacturers haveadopted SAE and international standards to varying degrees and have establishedtheir own EMC standards that the testing laboratory must follow closely. Table 2summarizes some of the relevant standards by reference number. A sample of automotive EMC standards parameter SAE GM Ford Toyota Int’lEMISSIONS CISPR TSC7026G 25 TSC7058G Radiated RF ES-XW2T- CISPR 25 J551/1, GMW3097 1A278-AC J551/5 Conducted RF CISPR 25 TSC7058G CISPR 25 CS-2009.1 Conducted J1113-42 _ ISO7637-2 transientRADIATED IMMUNITY J551/1, TSC7025G J551/12, ES-XW2T- ISO 11452-2, RF immunity J551/16, GMW3097 1A278-AC ISO 11452-3 J1113/28Magnetic field J551/17 CS-2009.1 TSC7001G immunity ISO 11452-8 J1113-22COUPLED TRANSIENTS Inductive J1113-12 ES-XW2T- TSC7001G coupled 1A278-AC transients GMW3097 ISO 7637-2 CS-2009.1CONDUCTED IMMUNITY Susceptibility J551/13 TSC7315G ISO 11452-4 J1113-2,3,4 ES-XW2T- J1113-11 GMW3097 1A278-AC TSC7001G ISO 7637-2, Transient ISO 7637-3 ESD J551/15 CS-2009.1 TSC7018G ISO 10605 J1113-132 “An Overview of Automotive EMC Standards, “Poul Anderson, IEEE EMC Symposium 2006 Proceedings, 2006,pp. 812-816. 6
  8. 8. The Ongoing Challenges in Automotive EMC ComplianceDue to the high cost of performing whole-vehicle EMC testing and the need toexpedite component integration, EMC testing is being performed at both thecomponent or module and chip levels. The results are then used to predictcompliance of the whole vehicle. Even without the added complexities of new HEVand EV propulsion systems, there are difficulties inherent in the existing testmethods. At the chip or IC level, test standards such as IEC 61967-x family and SAEJ145 2/3 do not fully predict installed EMC. The correlation between near- and far-field emissions may not hold, and the result is highly dependent on any externalwiring harness. Also, at the module or component level, similar ambiguities exist.Component testing, however, can still be useful for identifying potential EMCproblems.The introduction of HEV and EV propulsion systems clearly intensifies the challengesto existing test methods even more. High battery voltages reduce powertransmission losses, but the resulting higher system impedances can render invalidemissions test results obtained with the artificial networks described in CISPR 253.Battery and drive motor impedance and impedance changes can also become animportant factor in EMC. Worst-case RF emissions from vehicular power convertershave been observed under transient conditions of load and speed4. Unfortunately,measurement standards have not yet taken this observation into account.SummaryThe automotive EMC environment is in a constant state of flux as new onboardelectric devices, communications media (both wired and wireless), and new drivesystems are added. Consequently, both EMC standards writers and vendors findthemselves in a situation without fixed, agreed-upon testing procedures for assuringthe compatibility of vehicles and components in hybrid and all electric cars.Ongoing change is the only constant. Automakers need to continue with strictattention to detail and try to model tests to capture the newer issues and concernsthey come across. Component suppliers need to be aware of these concerns duringtheir development cycles. Manufacturers of after market products and “cross over”devices, such as various kinds of IT equipment now being used in vehicles need tobe cognizant of the requirements of the automotive EMC environments.Although automotive EMC standards are well-established by manufacturers andboth domestic and international standards-making bodies, refinements may be3 “High Voltage Automotive EMC Component Measurements Using an Artificial Network,” Nelson et. al.,IEEEProceedings 18th Int. Zurich Symposium on EMC, 2007, pp. 195-200.4 “HEV System EMC Investigation during Transient Operations,” Nelson and Aidam, IEEE Proceedings 18th Int.Zurich Symposium on EMC, 2007, pp. 205-208. 7
  9. 9. The Ongoing Challenges in Automotive EMC Complianceneeded to achieve better correlation between chip-level and component- ormodule-level measurements and whole vehicle testing. New HEV and EV drivesystems continue to add further challenge to automotive EMC testing.About IntertekAs a leading provider of quality safety solutions serving a wide range of industries around the world, Intertekhas the expertise, resources and global reach to support its customers through its network of more than 1,000laboratories and offices – 39 specializing in EMC testing – in more than 100 countries around the world.For more information regarding Intertek’s new developments, call 1-800-WORLDLAB or visit: www.intertek.comThis publication is copyright Intertek and may not be reproduced or transmitted in any form in whole or in part without the priorwritten permission of Intertek. While due care has been taken during the preparation of this document, Intertek cannot be heldresponsible for the accuracy of the information herein or for any consequence arising from it. Clients are encouraged to seek Intertek’scurrent advice on their specific needs before acting upon any of the content. 8