Conformity Magazine - February 2009 - (Page 12)

EMC for the Functional Safety of Automobiles © Martinased | Dreamstime.com d by EurIng Keith Armstrong, Cherry Clough Consultants lectronic sub-assemblies (ESAs) are being increasingly used where they could affect vehicle safety risks, including every aspect of drivetrain control, and many aspects of body control, including lighting, displays, indicators and mirrors. Anything that could affect the direct control of a vehicle, or could confuse other road users, is of concern [2]. Indeed, there are many current developments that are safetyrelated, such as automatic parking, intelligent cruise control, automatic lane following, vision-aids, and vehicle-to-vehicle telemetry (enables vehicles to start braking when traffic ahead slows, even when hidden around bends or in fog) that would not be possible without advanced electronics and its software. The problem is that all ESAs can suffer from errors, malfunctions and even permanent damage due to electromagnetic interference (EMI). Further, the EM environment is continually worsening due to the increasing use of electronic technologies in all areas of society, especially switch-mode power conversion and wireless communications. Another problem is that all ESAs rely on semiconductors, either as discrete or integrated circuits (ICs), and the continuing shrinkage in their internal silicon features and reductions in operating voltages are making them more susceptible to EMI. So, for several reasons, the importance of EMI to the safety of vehicular transport is increasing. Standards in all industry sectors, including the automotive industry, generally deal with EMI-related safety issues very poorly, if they even cover it at all [3] [4] [5]. The few that attempt to address these issues simply require the application of traditional EMC immunity tests that can never be sufficient for ensuring tolerable safety risks over the entire lifecycle, for reasons which we’ll described later. Figure 1 outlines the general situation at the time this article is being written. 12 Conformity february 2009 E Over the last ten years or so, there have been developments in applying risk management techniques to EMC to correctly address EMI-related safety issues. Specifically, there is IEC TS 61000-1-2 [7] (which is effectively the missing EMC Annex of the basic functional safety standard IEC 61508 [8]), and the IET’s new guide on “EMC for Functional Safety” [9]. Twelve Reasons Why EMC Testing is Insufficient for Safety (Also see references [1] [9] [10] [11] and [12].) 1. Anechoic Test Chambers Do Not Simulate Real EM Environments Traditional radiated field immunity tests specify anechoic test chambers, which are unlike all real-life EM environments experienced by road-going vehicles, so their results can differ markedly from real-life. Vehicle manufacturers overtest to address this and other shortcomings in their test methods, but over-testing cannot compensate for the deficiencies associated with anechoic chambers. Figure 1: Increasing safety risks due to EMI http://www.Dreamstime.com

Table of Contents Feed for the Digital Edition of Conformity Magazine - February 2009

Conformity Magazine - February 2009 Contents Editor's Note FCC Clarifies Closed Captioning Requirements for DTV Receivers Commission Cracks Down (For the Fifth Time!) On Junk Fax Marketer FDA Requests Comments on Global Harmonization Documents Australia Now Requires Solar Panel Testing and Certification EU Drafting New Directive on Toy Safety EU Commission Revises Standards List for EMC, R&TTE Directives Additional Standards Published For the EU's Medical Devices Directive EU Commission Publishes Additional Standards for Directives on Active Implantable, In Vitro Medical Devices EMC For the Functional Safety of Automobiles ESD Open Forum The ILAC Arrangement: Facilitating Trade Efficient Methodology for the EMI Analysis of Optical Transceivers Including PCBs and/or Flex Circuits The EuP Directive - Implementation, Design Requirements and Issues Chambers, Shielding, and Accessories Buyer's Guide CPSIA Lead Requirements Apply to Existing Inventory, Says CPSC CPSC Clarifies Certifcation Requirements Other CPSC Actions in the News IEC Standards Update Product Reviews UL standards Update Telcordia Standards Update From Our "You Can't Make This Stuff Up" Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - February 2009

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