IEEE EMC June 2010 Chapter Meeting Automotive EMC Component Specs - A Contemporary Perspective Essential PCB Design Rules IEEE_June 2010 © Arnie Nielsen Consulting LLC 1 Arnie Nielsen Consulting LLC [email protected] 248-305-8264 (M 248-982-0401) Instrumentation Engineer - 5 years Powertrain Hardware-Software Electronics Design Engineer - 10 years Tech Specialist - 22 years • • • • Electronic Design EMC Reliability Product Assurance Electronics - EMC Consulting - 5 years © Arnie Nielsen Consulting LLC 2 Consulting Projects Item Company Product 1 Compact Power Inc (LG Chem) Electric Vehicle Battery Electronics (Volt) 2 Holley Performance Products Electronic Throttle Body 3 Android Industries TPMS (wheel/tire assembly line) 4 Methode Electronics Center Cluster Stack 5 Vectrix Electric Motorcycle 6 RGIS Handheld Data Terminal (inventory) 7 GHPS (KDS) BLDC, DSP Amplifier 8 Kostal Electric Vehicle Connectors 9 MRM Vehicle Internet 10 BASF Shielding 11 Cobasys Electric Vehicle Battery Electronics 12 L3 Communications Vehicle Communications 13 Haitec Taiwan OEM Vehicle 14 LiteOn Body ECU 15 Whetron Keyless Entry, Auto Wiper 16 Calsonic Entertainment 17 eCho Immobilizer 18 Delta Power Distribution 19 Advanced Microelectronics Headlight Control 20 Elitech Technology Ltd Inverter 21 Delphi Power Sliding Door 22 Clarion Car PC (Infotainment) © Arnie Nielsen Consulting LLC 3 Meets all specifications but what are we missing ? But it met Specification ? © Arnie Nielsen Consulting LLC 4 Reference Sampling Documents, Books 1. EMC Specification, EMC-CS-2009 (http://www.fordemc.com) 2. EMC Design Guide for Printed Circuit Boards (http://www.fordemc.com) 3. Noise Reduction Techniques in Electronic Systems, Henry Ott 4. High Speed Digital Design, Howard Johnson 5. Introduction to Electromagnetic Compatibility, Clayton Paul 6. “In Compliance” Magazine 7. ITEM - Interference Technology © Arnie Nielsen Consulting LLC 5 Web Sites 1. www.fordemc.com 2. www.clev.clemson.edu/emc 3. http://www.compliance-club.com/ 4. http://www.interferencetechnology.com/ 5. emcesd.com, Doug Smith Organizatons 1. SAE EMC committees (EMC, EMI, EMR). Meet often, much faster publication turn around time than international organizations 2. IEEE, ISO, CISPR, others 3. SAE Reliability Committee © Arnie Nielsen Consulting LLC 6 Summary - Punch Line 1. Specs are idealized simulations, not “real world” 2. Much of industry specs based on old issues. 3. Much time and cost spent on non value exercises by contemporary practitioners due to limited knowledge of specification history - don’t know when to “hold or fold”. 4. Little time left for “sandboxing” 5. DV testing often late in design cycle - need more simple development testing to identify issues early. 6. Meeting spec not sufficient to mitigate field issues 7. Main goal is to minimize field issues not just pass specs. 8. More efficient EMC Process improvements: • Up-front analysis, focus on contemporary issues • Design guidelines implementation. • Simple development testing. • Realistic data analysis and acceptance criteria. © Arnie Nielsen Consulting LLC 7 Summary of Automotive EMC History 1970’s • Minimal electronics – radio • Mostly concerned with ignition system interference 1980’s • Electronics increasing - starting with electronic ignition, alternator voltage regulator, simple engine control • Quality of IC’s and manufacturing processes not mature • Automotive EMC design and test standards starting to be developed to address above (e.g. OEM, ISO, SAE). • EMC evolving, many issues 1990’s • Explosion of electronics • Automotive electronics technology maturing - IC’s, manufacturing processes, standards, testing • EMC specs and design practices becoming mature. © Arnie Nielsen Consulting LLC 8 Summary of Automotive EMC History 2000’s • Specs stabilizing, similar throughout industry. • Minimal EMC field issues (if design guidelines followed), mostly Conducted Immunity. • Many specialized organizations in place: OEM/Vendor EMC staff Testing facilities/staff Equipment vendors Regulators and regulations EMC committees • A lot of inertia, perspective limited. • Many OEM specs and International Standards exist (Different but similar): • • Ford, Mazda, GM, Hyundai, Toyota, Honda, BMW, Nissan, etc. • ISO, CISPR, SAE, JASO, EU, FCC, Mil-Std, etc EMC process has potential to be improved and simplified. © Arnie Nielsen Consulting LLC 9 Automotive EMC Standards SAE Document Vehicle J551-1 J551-2 J551-4 J551-5 J551-11 J551-12 J551-13 J551-14 J551-15 J551-16 J551-17 Component J1113-1 J1113-2 J1113-3 J1113-4 J1113-11 J1113-12 J1113-13 J1113-21 J1113-22 J1113-23 J1113-24 J1113-25 J1113-26 J1113-27 J1113-28 ----J1113-41 J1113-42 ----- Description Vehicle, General & Definitions Ignition Interference Radiated Emissions Electric Vehicle Emissions Immunity, Off-Vehicle Source Immunity, On-Board Transmitter Immunity, Bulk Current Injection (BCI) SAE Status International Equiv Cancelled Cancelled ISO 11451-1 CISPR 12 CISPR 25 Cancelled Cancelled Cancelled ISO 11451-2 ISO 11451-3 ISO 11451-4 Immunity, ESD Immunity, Reverberation Chamber Immunity, Power Lines ISO 10605 Component, General & Definitions Conducted Immunity, Power Leads Conducted Immunity, RF Power Injection. Immunity, BCI Immunity, Transients Immunity, Coupling Clamp ESD Immunity, Absorber Lined Chamber. Immunity, Power Lines, Magnetic Immunity, Stripline Immunity, TEM Cell Immunity, Tri-Plate Immunity, Power Lines, Electric Immunity, Reverb Chamber, Mode Stiring. Immunity, Reverb Chamber, Mode Tuning. Immunity, Portable Transmitters ISO 11452-1 ISO 11452-10 ISO 11452-7 ISO 11452-4 ISO 7637-2 ISO 7637-3 ISO 10605 ISO 11452-2 ISO 11452-8 ISO 11452-5 ISO 11452-3 Radiated Emissions, Narrowband Conducted Emissions, Transients Environmental Conditions and Testing for Electrical and Electronic Equipment – Part 2: Electrical Loads Cancelled Cancelled Cancelled ISO 11452-11 ISO 11452-9 Cancelled CISPR 25 ISO 7637-2 ISO 16750-2 © Arnie Nielsen Consulting LLC 10 Automotive EMC Standards SAE Document Description IC J1752-1 J1752-2 J1752-3 Misc J1812 J2556 J2628 Function Performance Status Class Power Spectral Density (PSD), RE Data Analysis Characterization, Conducted Immunity OEM (sample) EMC-CS-2009 MES PW 67600 GMW3097 DC-10614 TSC7001, et al 28401NDS02 ES96200 GS95002 Ford Mazda GM Chrysler Toyota Nissan Hyundai BMW Other Related 2004/104/EC European EMC Directive FCC Part 15J Emissions Mil-Std 461 Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment Handbook for Robustness Validation of Automotive Electrical/Electronic Modules (Old version published in 1978). SAE J1211 SAE Status IC, General & Definitions IC Radiated Emissions, Loop Probe IC Radiated Emissions, TEM Cell International Equiv IEC IEC IEC 4/2009 The Present Status of the International Automotive EMC Standards Poul Andersen, Poul Andersen Consulting 37249 Hebel Rd Richmond, Michigan 48062 USA [email protected] http://www.cvel.clemson.edu/auto/auto_emc_standards.html © Arnie Nielsen Consulting LLC 11 Causes - Relative Contributions 100 80 60 40 20 0 A=Customer Does Not Like Product (Requirements not specified or incorrect) B=System Does C=Can Not Not Fit Diagnose (Interfaces) Problem (Trouble Not Indicated) D=Component Failure E=Manufacturing Fault Examples of top 3 causes: A: Most american cars until recently B: Boeing 787 C: Most automotive electronics TNI > 50 % © Arnie Nielsen Consulting LLC 12 Test Methods/Limits Observations • Meeting EMC specs necessary but not sufficient to mitigate field issues - Main goal is to minimize field issues not just pass specs. • Originally, EMC for automotive electronics was poor so a lot of tests were “invented”. There were minimal design practices for automotive EMC. • Many EMC tests are idealized simulations of the real world. • Major purpose is repeatability, not necessarily what is required to find real world issues. • Most OEM specs and processes are very severe, time consuming and expensive to implement. • Diverts from time to “sand box” where many issues are found - focus on major contemporary concerns. • Contemporary electronics much improved. EMC is minor issue compared to “Big Picture” - see figure • DV testing often late in design cycle - need more simple development testing to identify issues early. © Arnie Nielsen Consulting LLC 13 Test Methods/Limits Observations • EMC testing is typically the first time the system is “rung out” (system components interconnected and functionally examined). • Testing methods have many limitations and compromises not appreciated by contemporary practitioners - don’t know when to “Hold or Fold” • Much testing addresses old issues with limited value add especially for modules that follow known basic EMC design rules and are mature. • Different people looking at the same data can come up with quite different conclusions depending on their background, insight and flexibility. • Considering how EMC testing is done (test setup and limits are much more severe than real world) should have more flexibility, especially when one considers that most EMC issues are 3-6 sigma events. © Arnie Nielsen Consulting LLC 14 Test Methods/Limits Observations • Simple pass-fail criteria (e.g. limit line) results in too much non value work (not real world issues). • Does not indicate degree of compliance • Hard to compare different samples - need variables data. • Should use statistical approach to make better business decisions • Issues not presently addressed (e.g.): • • • Temperature Combined stresses Part degradation • Power supply electrolytic cap • Battery impedance increase. • Cracked I/O caps • Worn out transient suppressor © Arnie Nielsen Consulting LLC 15 Test Methods/Limits Observations • Functional Safety concerns (e.g. Toyota unintended acceleration) generating potential new set of requirements. • Non Compliance = Prosecution • IET 2008 Guide on EMC for functional safety (177pages) • IEC 61508 - Functional safety of electrical/electronics/programmable electronic safety related systems (7 parts) • ISO 26262 - Road vehicles, Functional Safety. In development, adaptation of IEC 61508. Estimated July 2011. © Arnie Nielsen Consulting LLC 16 Conflicting Goals • The responsibility for meeting EMC requirements is the Product Design (PD) Engineer. • Although it is admirable for the EMC community to try and do the best job possible, it has a tendency to go to extremes regarding testing requirements and limits. • Such EMC groups are typically a separate community and have a narrow view. This may be in conflict with some of the realities of the PD engineer • Limited time on each project • Must address many other design and manufacturing aspects. • Keep to schedule. • Keep costs down (weigh cost/benefit). • Make a profit. © Arnie Nielsen Consulting LLC 17 EMC Process Improvements • Process has potential to be improved and simplified but its extremely hard to change and think “out of the box” with so much inertia (OEM/Vendor EMC staff, Testing facilities/staff, Equipment vendors, Regulators and regulations, EMC committees). • Fundamental test concepts not embraced by EMC community but essential for field issue mitigation. • Failures are good (early in design process) information theory • Randomness is good. • Litigation fears preventing any major change • May be perceived as making less severe. • Opinion - not really an issue © Arnie Nielsen Consulting LLC 18 EMC Process Improvements • Even so, certain practices can be implemented to improve the process: • EMC group should be integrated with systems engineering and not a separate organization (ideally co-located). • Up-Front analysis, focus on contemporary issues. • Verify design guidelines implementation • Simple early development testing • Realistic data analysis and acceptance criteria. • If product has already passed one OEM spec, other OEM’s should accept (minor alterations). • Limited focused testing for mature products. © Arnie Nielsen Consulting LLC 19 EMC Process Improvements - cont’d • One generic automotive EMC spec for the industry. • “A Generic Automotive (Tier1) EMC Test Standard”, http://www.autoemc.net/Standards/StandardsMain. htm • Many existing standards can make this relatively easy. Most OEM specs already use. • Vendors can design to one spec - Lowers staffing/time/cost and results in a better product for all. • Examples in other industries • Military = Mil-Std 461 • IC’s = JEDEC • Consumer = UL standards. © Arnie Nielsen Consulting LLC 20 Simple EMC Development Tools RE - Magnetic Field Probes © Arnie Nielsen Consulting LLC 21 Simple EMC Development Tools RE - RF Detector placed on wiring © Arnie Nielsen Consulting LLC 22 Simple EMC Development Tools RE - Digital Radio © Arnie Nielsen Consulting LLC 23 Simple EMC Development Tools • Noise Generator connected to Injection Clamp • Use for DUT Power Input Noise © Arnie Nielsen Consulting LLC 24 Simple EMC Development Tools Adjustable Current Injection Clamp © Arnie Nielsen Consulting LLC 25 Simple EMC Development Tools Magnetic Field - attach to Noise Generator © Arnie Nielsen Consulting LLC 26 Simple EMC Development Tools • ESD Gun - Modified Lighter • Apply in low light to see paths © Arnie Nielsen Consulting LLC 27 Radiated Immunity © Arnie Nielsen Consulting LLC 28 General Setup for Radiated Immunity and Emissions © Arnie Nielsen Consulting LLC 29 Radiated Immunity (RI) Observations • Test not like real world • Test = Alignment of antenna and DUT/Harness maximizes susceptibility • Real = Random harness routing, inefficient coupling, sheet metal. • Test = Exposes large area • Real = Exposure to only part of system. • OEM limits too severe (Ref Mil-Std 461 ground = 50 v/m max). • High limit based on high power on-board transmitters (rare these days). • Contemporary = Cell Phones (only for certain DUT’s): “Cell Phone Interference in Automotive Cabin”, Craig Fanning © Arnie Nielsen Consulting LLC 30 Radiated Immunity (RI) Observations • Field strength varies widely in actual vehicle - can be >100 v/m difference only a few inches apart. • Real = Field falls off rapidly from point source. • Field impedance (E/H) different for test vs vehicle. • Proposal - Use more realistic data analysis based on probability of concern and realization of how limit was determined. • Example = determine susceptibility field strength average and standard deviation. • Only resolution needed to make engineering business decision is high, medium and low (e.g. test at 100v/m but acceptable at 80 v/m) © Arnie Nielsen Consulting LLC 31 Example of RI Data • • • Does it meet intent of 100 v/m ? CW, 400-1000 MHz Average = 83 v/m, Std Deviation = 13 v/m © Arnie Nielsen Consulting LLC 32 Radiated Emissions © Arnie Nielsen Consulting LLC 33 Radiated Emissions (RE) Observations • Test not like real world • Test = Alignment of antenna and DUT/Harness maximizes emissions measurements • Real = Random harness routing, inefficient coupling, sheet metal. • Many specs overcomplicate their RE limits by having many bands and associated limits. The limits are only applicable in a lab environment for a particular setup. In the vehicle, there are many variables which amplify or attenuate the signal.. • Limits are good only for test setup, changes with different harness lengths (up to 20 dB differences). • “Automotive EMC Test Harnesses, Standard Lengths and their Effect on Radiated Emissions”, Martin O’Hara, James Colebrooke • Spectrum Analyzer/Receiver not like real radio © Arnie Nielsen Consulting LLC 34 RE Spec Limits • The main factor that determines a spec. limit are the sensitivities of on-board or nearby radio and communication antennas and receivers. • In the AM band, the antenna factor (ratio of antenna output voltage to field strength) plus the attenuation from the antenna to the radio due to antenna cable capacitance is about 20 dB. • In addition, there is some attenuation between noise sources within the vehicle and the antenna due to sheet metal and differences in polarization. • Assuming a radio sensitivity of 1 uv (0 dbuv), the limit = 30 dbuv/m (20 + 10) © Arnie Nielsen Consulting LLC 35 RE Limits, cont’d • For FM entertainment radio and mobile communications, the antennas and antenna cable is much more efficient (antenna factor is 0 - 6 dB) and attenuation due to the vehicle sheet metal (openings, slots) is less due to small signal wavelength. • Assuming a 1 uv sensitivity, the limit = 10 dbuv/m. • The limit increases at 20 db/decade at higher frequencies to account for the fact that radio receiver antenna output voltage decreases at that rate (aperture size of a tuned antenna decreases with frequency). This can be seen by the following equation which shows the (1/f) relation (20 db/decade): e = (33 * E) / f (quarter wavelength antenna) e = antenna output voltage, E = field strength (v/m) impinging on antenna f = frequency (MHz) © Arnie Nielsen Consulting LLC 36 RE Spec Limits, cont’d • The following equation provides useful conversions for testing: dBuv/meter = dBm (reading of spectrum analyzer) + 107 (converts power across 50 ohms of spectrum analyzer to volt) - preamp gain in db (if used) + AF in dB (antenna factor, changes with antenna/frequency) • For example, a reading of - 60 dBm on the spectrum analyzer at 100 MHz (assuming 26 dB amplifier in series with spectrum analyzer) would be: dbuv/meter = -60 + 107 - 26 + 14 = 35 dBuv/meter = 56 uv/meter © Arnie Nielsen Consulting LLC 37 © Arnie Nielsen Consulting LLC 38 • Typical OEM limits are much more stringent than the FCC's, especially when one considers that FCC limits are measured 3 meters away from the radiating device and the OEM limits are at 1 meter. The typical OEM limits are more restrictive: • Radiating devices on the vehicle are closer to radio transceivers on board the vehicle. • A vehicle contains many radiating devices. • Customer satisfaction OEM RE limits (1 meter) typical Frequency (MHz) uV/m dBuV/m 0.10 - 25 31.6 30 25 - 200 3.2 10 200 - 1000 3.2 - 15.8 10 dBV/m - 24 dBV/m FCC Class B RE limits (3 meters) 30 - 88 100 40 88 - 216 150 43.5 216 - 1000 200 46 © Arnie Nielsen Consulting LLC 39 Example of RE Data • Which One is Acceptable ? • Top = Few spikes over Limit, technically fails • Bottom = All spikes under Limit, technically passes © Arnie Nielsen Consulting LLC 40 Example of Using the Wrong Part Early detection would prevent multiple layouts © Arnie Nielsen Consulting LLC 41 RE Data Analysis Reference SAE J2556 • The present method of using only a limit line for determining module radiated emissions acceptance is too simplistic and is not the most effective way to make competitive business decisions. The limit line approach does not address many real issues. • It is very difficult if not unpractical to get the same results at each frequency from different test labs for radiated emissions due to the many variables involved. • However, it is possible to establish correlation between different labs on a statistical basis. For example, if only the highest emission levels are compared independent of the emission frequencies a higher degree of correlation is possible. • Such an approach may be justified under the assumption that the test facility design does not significantly affect the total emissions power but mainly leads to the radiated power spectrum redistribution. © Arnie Nielsen Consulting LLC 42 • The simplistic approach of being below a limit line may still result in instances of a customer concern. • For example, even if the RE is all below a limit line, it is more probable that a concern would exist if there are many spectral lines close to the limit (i.e. the spectral density is high). • Another situation that may result in overdesign would be to fail a module that only had a few data points slightly over the limit but otherwise showed little emissions. • There are many differences between the module test setup and the vehicle configuration (e.g. harness configuration) and it is unlikely that there is a one to one correlation between the lab and the vehicle (at each frequency). • For example, even if a module was below a limit line using the bench test configuration, in the vehicle there may be an entirely different configuration so that those frequencies that were below the limit line are now connected to a system which more effectively radiates and results in a customer concern (and conversely). © Arnie Nielsen Consulting LLC 43 PSD Calculation If there are narrowband (discrete peaks) emissions above a Preferred Limit and any peak does not exceed a defined level (e.g. 6 dB) over this Preferred Limit. There is a high density of spectral lines near the limit (e.g. within 3 dB). 1. Consider the data points in terms of (x/L) 2 where x is the value of the data point in linear terms (uv/m) and L is the preferred limit at the frequency of the data point. For example, if a data point is 20dB uv/m (10 uv/m) and the preferred limit at that frequency is 10dB uv/m (3.2 uv/m), the (x/L) 2 value would be (10/3.2) 2 = 9.8. The squaring gives exponentially more weight to data points that are high relative to a preferred limit. It also gives an indication of spectral power hence the PSD designation (receivers are sensitive to power impinging on their antenna). 2. Compute Power Spectral Density (PSD) for a given frequency span: PSD = ∑ (x / L) 2 / (Frequency Span / Resolution) © Arnie Nielsen Consulting LLC 44 PSD Example © Arnie Nielsen Consulting LLC 45 Conducted Immunity © Arnie Nielsen Consulting LLC 46 Sampling of OEM Specs - CI OEM Test Name Type Parameters Ford, ES-XW7T-1A278-AC CI 210 Sine 50-10KHz, stepped CI 220 A1 CI 220 A2 CI 220 B1 CI 220 B2 CI 220 C CI220 D-G CI 230 A-D, Pwr Cyc CI 260 A-C, Dropout Transient Transient Transient Transient Transient Transient Complex Sq Wave CI 260 D, Dip Sq Wave CI 260 E, Bat Recov CI 260 F, Random Complex Complex Ramp BMW, GS 95002 Ripple Sine 50-20k, 1min sweep BMW, GS 95003-2 Ramp Engine Start Dip, Very Brief Dip, Brief Complex Complex Complex ISO 7637-2 Ramps, sine 0-Ubmax, 1v/min ISO Pulse 4 0.5v steps Hyundai, ES-X82010 Voltage Fluctuaton Dip Ramp Engine Start Engine Start Chattering Ign Key Intermittent Instantaneous Interrupt Triangle Complex Triangle Complex Complex Sq Wave Sq Wave Sq Wave 8-16v, 1v/sec Single 100ms dip (ramp) 0-12v, 0.1v/s-1v/min 5-12v ISO Pulse 4 5 pulses, 10-50ms 5 pulses, 0.5-3s Single pulses, 1ms-20ms GMW3172 Voltage Drop Voltage Dropout Superimposed Volt ISO Pulses 1-5 Dips Complex Sine Transients 5% steps from V-min, PW=5 sec Ramps Sweep, 2 superimposed, 1-12KHz, 12-72KHz ISO 7637-2 ISO Pulses 1-5 Transients ISO 7637-2 Slow volt Inc/Dec Re-initialization Micro-interruptions Triangle Dips Dropouts Starting Ripple Complex Sine V-nom to 0, 0.5v/min 5% steps from V-nom, PW=5 sec V-nom to 0v, PW=10us to 300ms Ramps, sine Sweep 50Hz-20KHz Ripple Drop Out Voltage Dip Low Voltage Mem Ramp up Ramp down Transients Sine Dips Dips Complex Complex Complex ISO 7637-2 15Hz-250KHz 11 to 0v, 10us-1sec 11 to 5.5-3v, 100us-.5s Ramp, 12.6v-6.5 Ramp (50mv max step), 0v-Vmax, .1-60sec Ramp (50mv max step), Vmin-0v GMW3097, GMW3100 Nissan, 28401NDS02 DCX, DC 10614 DCX, DC-10615DR2 © Arnie Nielsen Consulting LLC 47 Conducted Immunity Observations • Majority of contemporary EMC field issues are in this category. • Randomness is good for detecting issues - foreign to test community. • Hot plugging (or missing/late ground) has been identified as major reason for Electrical Overstress • Often misidentified as ESD • Bosch SAE paper 2009 (2009-01-0294) • USB and OBD (Europe) connectors use extended ground pins. © Arnie Nielsen Consulting LLC 48 Load Dump • Most every spec has wrong test simulator. • Many modules over-designed using typical simulators. © Arnie Nielsen Consulting LLC 49 Load Dump Analysis © Arnie Nielsen Consulting LLC 50 • Load Dump is a big concern since it exposes electronic components to very high energy levels that may cause damage. • Due to the sudden disconnection of electrical load from the alternator while operating without a battery or a discharged battery. • These conditions can exist, for example, with a loose battery terminal, damaged battery or during a jump start. • A simplified model of the alternator is a voltage source (Vs) in series with a resistance (function of Alternator RPM). • Vs = Constant * Field current * alternator RPM • If there is a sudden disconnection of load current, the alternator terminal voltage suddenly increases (voltage drop across alternator resistance decreases). • Duration of this transient is dependent on how long it takes the field circuit to bring the alternator into normal voltage regulation (the time constant of the alternator field coil). © Arnie Nielsen Consulting LLC 51 • A realistic simulator was determined by building actual alternator driven by electric motor and comparing results on actual DUT’s. • Historical simulator circuits only looked at energy equivalency but this model also looked at the Action Integral. ∫ I 2 dt • Historical simulators damaged MOV but actual alternator did not (although same energy delivered to MOV) • Difference was Action Integral. Simulator built to give approximate same Action Integral as actual alternator. Schaffner simulator = 38 A 2 sec Actual Alternator = 8 New simulator = 10 © Arnie Nielsen Consulting LLC 52 Load Dump Test Procedure Calibration: • Set transient generator to specified voltage with the DUT disconnected and SW1 open (open circuit). • Verify voltage waveform across R4 - with DUT disconnected and SW1 closed. Test: • If Central Load Dump is being evaluated, add alternator zener diode (nominal 33V peak) across DUT after calibration. • All circuits under test shall be exposed simultaneously (at test fixture). Note that in some cases this will also subject certain DUT outputs if they are connected through a load to power. • Connect DUT, close SW1 and subject to specified transients. • Functionally test ESC at nominal voltage after this test. © Arnie Nielsen Consulting LLC 53 ISO 7637 • Many specs use ISO 7637 for transients • ISO 7637 transients too idealized • Simulation not real or effective - charge up cap then discharge through resistor network. • Developed in days of ignition breaker points. • Out of date, developed over 30 years ago • Ford EMC spec only realistic version (in appendix of latest 7637). Recreates actual mechanism • IEEE, 2005, “Comparison of ISO 7637 Transient Waveforms to Real World Automotive Transient Phenomena” Keith Frazier, Sheran Alles © Arnie Nielsen Consulting LLC 54 Mechanical Contact Characteristics 1. 2. 3. 4. 5. 6. 7. 8. 9. Contacts start to move apart. Switch current suddenly goes to zero. L current continues dV/dt = I / C Distance increases and Vf increases. Rise of Vf slower than rise of V (Mechanical inertia). Repetitive flashovers occur. Air breakdown means Switch voltage = 0. C discharges into network. Continues until energy dissipated and can’t flashover. © Arnie Nielsen Consulting LLC 55 © Arnie Nielsen Consulting LLC 56 Transients - ISO Example Conclusion = Not realistic simulation © Arnie Nielsen Consulting LLC 57 © Arnie Nielsen Consulting LLC 58 © Arnie Nielsen Consulting LLC 59 © Arnie Nielsen Consulting LLC 60 © Arnie Nielsen Consulting LLC 61 Inductor Suppression Diode Placement Near inductor - provides protection for intermittent wiring harness opens. Worse for Radiated Emissions (RE). Larger loop area for fast rise/fall times. Near driver - reduces RE © Arnie Nielsen Consulting LLC 62 © Arnie Nielsen Consulting LLC 63 SAE J2628 Details © Arnie Nielsen Consulting LLC 64 SAE J2628 (2007) - Characterization, Conducted Immunity 1. Addresses Major Issues • Design Margins • Voltage Interruptions and Transients • Power Dropouts and Dips • Current Draw • Switch Input Noise 2. Existing ISO Type Transients (e.g. ISO 7637) not realistic or effective. 3. Collaborated with Ford EMC group (Keith Frazier) to develop realistic simulations. © Arnie Nielsen Consulting LLC 65 SAE J2628, Design Margins © Arnie Nielsen Consulting LLC 66 Design Margins Example © Arnie Nielsen Consulting LLC 67 Chattering Relay Configuration © Arnie Nielsen Consulting LLC 68 Power Cycle, Power Interruptions During Start-Up (Waveform F) The purpose of this test is to verify proper DUT startup during ignition key-on (ignition switch or relay bounce) which can be severe over the full vehicle temperature range. This is especially important for verifying proper software initialization. Relay 2 provides the power on-off cycle and relay 1 is connected in a chattering configuration to provide the random noise representing contact bounce at power up and after. © Arnie Nielsen Consulting LLC 69 © Arnie Nielsen Consulting LLC 70 Inductive Transients - Pulse A1, A2, C Pulse A1 and A2 simulates the transients produced by switching off power to the DUT and an inductive load (L) that is in parallel with the DUT. Pulse C is produced by switching off an inductive load that shares a common power feed with the DUT. © Arnie Nielsen Consulting LLC 71 Inductive Transients - Pulse A1, A2, C Test Mode SW2 Closed = 220 Ω SW3 Closed = 10nF SW4 Closed = 6 Ω (Hi Current) Open = 39 Ω (Lo Current) 1, 2 SW1 Closed = Non Chattering Open = Chattering Closed A1 Closed Closed Closed A1-a (1) 1 Open Open Open Closed A2-1 1 Closed Open Open Open A2-1, C-1 2 Closed Open Open Open A2-1, C-1 3 Open Open Open Open A2-2, C-2 2 Closed Open Closed Open A2-2, C-2 3 Open Open Closed Open (1) Special for Development Mode 1 = 0.2 Hz, 10% Duty Cycle Mode 2 = Pseudo Random Sequence Mode 3 = Same as mode 2 but with chattering relay © Arnie Nielsen Consulting LLC 72 A1 A1a - Chattering A2 C © Arnie Nielsen Consulting LLC 73 Inductive Transients - Pulse B1, B2. Note: Deleted in Ford EMC-CS-2009 Pulse B1 and B2 simulates low side switching of an inductive load and applies to DUT signal inputs that are connected across the switch (e.g. A/C clutch monitor). The pulse is produced at the start of period T1 when relay 3 contact opens. R3 provides adjustment of current through L2 to give different waveform characteristics (B1 = high current, B2 = low current). B1 B2 © Arnie Nielsen Consulting LLC 74 SAE J2628 - Power Dropouts, Dips • Voltage Dropouts - high impedance (open circuit) typically due to poor connections (e.g. hitting pothole). • Voltage Dips • Low impedance most commonly experienced during engine starting. • These dips can also occur as a result of a poor battery connection when a high current load is activated. • Voltage dips can also be used to evaluate DUT voltage regulator input step response by monitoring the regulator output and looking for stability (limited overshoot, limited ringing). • These waveforms apply to all power supply and control circuits. © Arnie Nielsen Consulting LLC 75 SAE J2628 – Power Dropout, Dips Test Up, U1 3 cycles separated by 20 s High 13.5 100us, 300us, 500us, 1ms, 3ms, 5ms, 10ms, 30ms, 50ms Same as Test A Acceptance Criteria II Same as Test A High II C 13.5 100us, 200us, 400us Same as Test A High I D 13.5, 5.0 Same as Test A Same as Test A Low II A 13.5 B T (1) Duration Impedance 1. Waveform transition time approximately 10us. © Arnie Nielsen Consulting LLC 76 Pulses A, B, C, D UP 10T 9T 7T 8T T 2T 0V UP 10T 0V T 9T T 8T 7T T T 2T T T T T UP 0V T UP 10T U1 T 9T T 8T T 7T T T 2T T T T T 0V © Arnie Nielsen Consulting LLC 77 SAE J2628 - Current Draw • Measure True RMS current under various voltages and temperatures • Good indicator of: • Normal DUT Operation • DUT degradation • Inadvertent design-manufacturing changes (conformity) • Sneak paths © Arnie Nielsen Consulting LLC 78 System Degradation Example Switch Input • Validation typically done with “pristine switches. Open = infinity, closed = 0 ohms, minimal switch bounce. • More realistic test configuration shown below. © Arnie Nielsen Consulting LLC 79 SAE J2628 – Switch Input Noise • Creates random bounce at switch transitions. • Includes non ideal switch impedances. © Arnie Nielsen Consulting LLC 80 Electrostatic Discharge (ESD) © Arnie Nielsen Consulting LLC 81 © Arnie Nielsen Consulting LLC 82 • Handling - too many test strikes, cumulative damage, will only see a few (at most) in the field. • ESD is highly variable event - many variables (e.g. humidity, approach speed, module positioning above ground plane) • Plastic parts hold charge - use air ionizer to neutralize. Important when testing - subsequent discharges not like first one due to charge buildup. • ESD can cause “walking wounded” - looks OK after test but fails when exposed to other stress. • The order of applying ESD discharges (in total test sequence) is important. • Most methods used for RF Radiated Immunity also apply to ESD protection. • Some mechanical ESD events not tested - e.g. underhood ESD from belts/pulleys, tire/bearings, low carbon tires, fuel filter, etc. • Hot Plugging shown to be issue - often misdiagnosed as ESD. © Arnie Nielsen Consulting LLC 83 Spark Gap PCB - Test Configuration SMD resistor value shift used to determine effectiveness of gap configurations Placed on Ground Plane © Arnie Nielsen Consulting LLC 84 Spark Gap Test Results A. Nielsen, 7Oct2004 10 KV 14 KV Co nfigu ratio n To tal # Hits Avg % S td Dev % Total # Hits Avg % Std Dev % 1 No Spark Gap or Cap 13 10.7 3.7 2 0.005 Air Gap 33 3 2.1 33 4.6 1.9 3 Add MDB 69 0.7 0.5 66 1.1 0.6 4 0.010 Air Gap 33 5.6 2 30 6.7 1.7 5 Add MDB 72 1.1 0.9 72 1.8 1.0 6 0.015 Air Gap 33 6.7 2.4 30 7.8 2.6 7 Add MDB 72 1.3 0.9 72 2.0 0.9 PCB: 4.5 x 6 inch, Ground plane, Multiple gaps ( unused gaps covered with Hum-Seal). Compound = MDB-06-073, Thermoset encapsulant with adhesion additive. Resistors = 2010 SMD, 10 K Measurement = % shift in resistor value. Test Setups: 1. PCB raised 3/8 inch above bench ground plane. 2. PCB ground connected directly to bench ground plane. Procedure (Generally, some deviations): 6 hits, replace resistors before going to next set of hits. Conclusions: • Spark gaps do provide some protection, especially at small gaps. • Protection at practical gap sizes is very limited. Product may function, but is weakened (walking wounded). • Coating spark gap with special compound improves (also protects for dendritic growth). © Arnie Nielsen Consulting LLC 85 General Test Requirements © Arnie Nielsen Consulting LLC 86 Monitoring • Too much monitoring creates its own set of problems • Spend too much time debugging specialized test software or hardware. • Diverts from finding real concerns. Acceptance Criteria • Often too severe or arbitrarily chosen. • Majority should be what the customer would notice not necessarily what the component spec limits are. Development Testing • Development testing should be done by design engineer - interactive process, failures are good. • Often done without regard to the cost/time/value. • Appreciate the need to get to root cause but sometimes it’s for the sake of satisfying an engineer’s curiosity and is not a good business decision. © Arnie Nielsen Consulting LLC 87 Component Test Plan The quality of event is highly dependent on preparation. Poor test preparation has historically resulted in retests and a lot of non-value work. 1.0 Introduction 1.1 Product Family Description 1.2 Theory of Operation 1.3 Physical Construction 1.4 EMC Specification Release 1.5 Approved Test Facility 1.6 Component Part Number(s) 1.7 Component Manufacturer(s) 1.8 Component Usage 2.0 EMC Requirements Analysis 2.1 Critical Interface Signals 2.2 Potential Sources of Emissions 2.3 Component Surrogate selection 3.0 Test Design and Requirements 3.1 Component Operating Modes/Functional Classifications 3.2 Test Requirements 3.3 Input Requirements 3.4 Output Requirements 3.5 Load Box/Test Support Requirements 4.0 Test Setups 5.0 Test Report Requirements © Arnie Nielsen Consulting LLC 88 © Arnie Nielsen Consulting LLC 89 Designing PCB for EMC, Essential Design Rules (Ref Word Document) © Arnie Nielsen Consulting LLC 90 PCB Layout Examples - Filter Connectors (1980) © Arnie Nielsen Consulting LLC 91 PCB Layout Examples - Radio Old (many grounds) vs New (one good ground) © Arnie Nielsen Consulting LLC 92 PCB Layout Examples - EEC © Arnie Nielsen Consulting LLC 93 PCB Layout Examples - Cluster © Arnie Nielsen Consulting LLC 94 Supplemental Product Assurance Information Product Assurance Robustness (PAR) © Arnie Nielsen Consulting LLC 95 Key Elements • Product Assurance Robustness (PAR) Plan • Specifically designed to address contemporary Issues. Based on case histories comparing detection capability of Traditional vs. PAR. • Similar philosophy to best OEM’s - Focus on potential weaknesses early. • Emphasis on Analysis and Development testing Most “Real World’ issues not found in DV. • Best if multi-discipline analysis by expert(s) who know what to focus on. • Use surrogate data to reduce non-value testing. • Reduce sample size - Allows increased monitoring and less facilities (allows more focusing on product and not on test complexity "red herring" issues). © Arnie Nielsen Consulting LLC 96 • Focused testing and measuring degradation (not just failures). • Addresses system interaction and degradation. • Combines EMC and Non EMC environments. • If fully implemented, less overall time-cost ( >50 % possible) and more effective. • Viewed as risk since different - actually more rigorous • Successfully used on complex programs where no OEM specs exist (aftermarket) - TacNet (Police), Dockable Family Entertainment System, etc. • Degree of implementation depends on maturity level (experience) of OEM and Vendor. • SAE J1211 revision (2008) and SAE J2628 (2007) reflects this philosophy. © Arnie Nielsen Consulting LLC 97 Three PAR Stages - Summary 1. Analysis - Requirements, Thermal, Mechanical, Electrical, Reliability, Referential Data - Use of experts emphasized (electrical, mechanical, etc) to focus testing. 2. Development - Formalized testing based on analysis. • Besides analysis, this is where real issues are identified. • Allows max flexibility to experiment and sufficient reaction time. • Stage where failures are good (maximize information). • Simple and low cost techniques that requires minimal lab facilities. • Uses Product Assurance Robustness (PAR) tester, Ref SAE J2628 © Arnie Nielsen Consulting LLC 98 Development Tests Type ID Name Description General G-10 Internal Inspection Solder Joints, Connectors, etc G-20 Functionality Emphasis on Transition States. C-10 Design Margins Ramp Voltage, Upper-Lower Operating Limits (UOL, LOL) Multiple Temps, Two Methods (Rigorous, Abbreviated), Includes C-20. C-20 Interruptions, Transients Power Interruptions, Transients C-30 Power Dips Various Pulse Widths and Voltages C-50 Current Draw True RMS Current During Power On-Off, Multiple Temps. C-60 Overvoltage True RMS Current at 19v, 24 v, Multiple Temps. C-70 Reverse Battery Current True RMS Current at -14 v C-80 Oscillator Function Momentary Short Oscillator, Verify Recovery Characterization © Arnie Nielsen Consulting LLC 99 Development Tests, Cont’d Type ID Name Description Failure Modes FM-10 Shorts to Power-Ground 0.3 ohms, Monitor Current During Shorts FM-20 Load Faults Opens, Partial Shorts in Certain Loads FM-30 Leakage Resistance All pins = 50K to Power or Ground FM-40 Sneak Paths, Opens Open Power-Ground to DUT (at DUT) EMC-10 RF Immunity Bulk Current Injection (BCI) EMC-20 Emissions Current Probe on Harness or AM/FM Radio EMC-30 ESD Pins = +/- 10kv, Controls = +/- 15kv EMC-40 Crosstalk Noise From Chattering Relay Coupled by Parallel Wire Env-10 Moisture Immunity Apply Windex Directly to PCB, Verify No Combustion. Env-20 Mechanical Disturbance Plastic Hammer, Drop (15cm), Flexing of PCB Env-30 Resonant Search Identify Potential Vibration Issues Env-40 High Temp Exposure Monitor Suspect Hot Points. Hot Box if Applicable Env-50 Combined Envir Exposure EMC-RF Environmental High Temp-Humidity-Shock © Arnie Nielsen Consulting LLC 100 3. Validation - (Qualification, Endurance) • This is often “Test for Success” oriented - “Feel Good” testing that can give false sense of acceptability. • Specified by customer - Plan depends on OEM flexibility. Simplify (e.g. surrogate data, focus on what’s new, etc) © Arnie Nielsen Consulting LLC 101 Traditional vs PAR Summary Stage 1. Analysis Traditional PAR 1. Define Requirements 1. Define Requirements 2. Expertise Distributed – Analysis Piecemeal 2. Multi-Disciplined Perspective (Broad Experience). 3. Little Synergy to Identify Weaknesses. 3. Identifying Weaknesses Critical - Where to Focus. 2. Development 1. Not Required or Limited. 1. Main Focus - More Important than DV 2. Waiting for DV to Detect Concerns. 2. Formalized Series of Simple Tests. 3. Low Cost, Minimal Lab Facilities. 4. Typically Takes 3 days. 5. Failure is Good - Maximizes Information 6. Identifies Concerns Early. 3. Validation 1. Cookbook Test Procedures. 1. Small Sample Size. 2. Late in Program 2. More of Systems Approach. 3. Large Sample Sizes. 3. Heavy Use of Surrogate Data. 4. "Test for Success", Feel Good Results. 4. More Focused on Weaknesses. 5. Limited "Play Time" to Find Customer Issues. 5. Key Life Test Looking at Degradation (Not Failure). 6. Software Validation Under Pristine Conditions © Arnie Nielsen Consulting LLC 102 © Arnie Nielsen Consulting LLC 103 Description Approach Surrogate Data Cost, Test Time Effectiveness Test for Success Sample Size Monitoring Test Configuration Time Compression where Possible EMC Testing Item 1 2 3 4 5 6 7 8 9 10 Done separately at room temp. Not applied sufficiently Artificial loads, minimal interfaces Limited Large Majority of tests Minimal Expensive, Long Varies Traditional Process Cookbook Supplemented by more realistic Conducted Immunity testing in Development Stage. Reference SAE J2628 Example: Reduce dwell times on thermal cycling/shock. Measure DUT board temp and set dwells to stabilization + 5 minutes. Use surrogate data to only run the test required to verify the unknown. Sub-system with realistic loads and interfaces (allowed by reduced sample size). Continuous monitoring (allowed by smaller sample size) Smaller, reduced facilities with the focus on what’s needed to verify the unknown. Some but also generates variable data (test to failure or measuring degradation). More effective. Aimed at contemporary issues Focused on what is unknown. Potential to reduce by 50% or more. Maximize to reduce non value testing. Tailored test plan utilizing historical data, analysis and development testing to focus on potential product weaknesses and changes. Intelligent Testing Process Actual Example Plan Note - Although PAR much shorter, plan is better (customized to address many issues not in original) OEM Original Request PAR - OEM Approved Analysis Moderate Similar but also Developed Focused Test Plan Development Test Time No 24 hr (3 X 8 hr) DV Sample Size 12 6 DV Cumulative Test Time 3000 hr 400 hr Key Life Test Time 4800 hr 300 hr Overall Total Test Time 7800 hr 700 Note: software validation, EMC additional © Arnie Nielsen Consulting LLC 104 PAR Support Hardware © Arnie Nielsen Consulting LLC 105 Product Assurance Robustness (PAR) Tester • Based on real world issues often missed in typical Product Assurance/Validation process. • Uses simple, low cost techniques and includes many functions in one package (does not require a test laboratory environment). • Makes it practical for Hardware-Software Robustness and Design Margin testing throughout the design process. Enables early detection of issues and a lean testing process. • Capability to do many OEM, ISO, etc Conducted Immunity EMC tests. • Recreates “real world” transient events (unlike the unrealistic simulations of ISO 7637). © Arnie Nielsen Consulting LLC 106 PAR Tester Cont’d • Creates other waveforms via a 2 channel Arbitrary Waveform Generator (AWG) and 2 channel DC power amplifier. Fast waveforms use the Electronic Switch module. • Evaluates non ideal DUT switch signal inputs via a 4 channel switch simulator that creates random noise on switch transitions. Also simulates non ideal switch impedances. © Arnie Nielsen Consulting LLC 107 1. DC Power Amplifiers: a. Power Op Amps - switching power supplies. b. 0-20 KHz, 0-24 volts. c. Two Channels (150 and 50 watts) 2. Arbitrary Waveform Generator (AWG): a. 2 channels b. PC Controlled via USB c. Easy to use waveform editor. 3. Electronic Switch, DC voltage source a. 1us rise/fall time b. Capability = 10 amps c. Voltage Source = 1.5 - 20 volts, 1.5 amp (Higher currents available via DC Amp) © Arnie Nielsen Consulting LLC 108 4. Transient Generator: Uses inductors and relays (including chattering relay) to simulate vehicle Transients per SAE J2628 and Ford EMC spec. 5. Switch Noise Simulator: a. Creates random bounce at switch transitions (adjustable) b. 4 channels, separate or simultaneous activation. c. Includes non ideal switch impedances. Contents: Rack Assembly, Enclosure (pull handle, wheels), DC Amps, Electronic Switch, Switch Noise Simulator, Transient Generator, AWG, Waveform files, User manual. Weight approx 30 lbs Contact: Arnie Nielsen, (248) 305-8264, [email protected] © Arnie Nielsen Consulting LLC 109 © Arnie Nielsen Consulting LLC 110 © Arnie Nielsen Consulting LLC 111
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