EMI/EMC of Entire Automotive Vehicles and Critical PCB s. Makoto Suzuki Ansoft Corporation

Transcription

1 EMI/EMC of Entire Automotive Vehicles and Critical PCB s Makoto Suzuki Ansoft Corporation

2 WT10_SI EMI/EMC of Entire Automotive Vehicles and Critical PCB s Akira Ohta, Toru Watanabe, Benson Wei Makoto Suzuki Ansoft Japan K.K., Ansoft Corp. Taiwan Branch

3 Agendas First step of EMI/EMC EMI / EMS / Coupling process LC devices and EMI filters Parallel plates resonance analyses Plane impedance & Noise level@3m field The design flow of a PC board design Actual noise suppression methods for PC boards Entire automotive vehicles and critical PC boards EM analysis of a full size car body with PC boards

4 Three elements of EMC Conduction Coupling process EMI EMI source source Emission Space & Field Conductive Capacitive Inductive Radiative Low, Middle & High Frequency Low & Middle Frequency LC Resonance High Frequency EMS EMS Immunity EMI, EMS, Coupling process Three elements of the noise problem

5 Noise suppression Coupling process Conduction EMI EMI Filters Filters EMI EMI source source Emission Shields Shields Space & Field Conductive Capacitive Inductive Radiative EMI Filters Low, Middle & High EMI Filters Frequency Shields Shields Shields Shields Low & Middle Frequency LC Resonance Shields Shields High Frequency Which should we touch EMI source? or victims? Immunity Immunity EMS

6 Normal mode & Common mode noise A PC Board & Cables A victim device Normal mode current A Driver & Receiver by AC Analysis of Q3D Extractor Normal mode current flows --- Loop Common mode current flows --- Open We can see Common mode current is more serious than Normal mode. Common mode current

7 By the Antenna theory -A Normal mode current flow Loop antenna theory -A Common mode current flow Dipole antenna theory E = (f r 2 AI) sin θ E = 7 4π 10 ( f Il) sinθ r A : area of the loop θ r : distance θ r Length :l I I Illustration of a loop antenna Illustration of a dipole antenna FCC B level Mag. E limit 3m Mag. E( Loop antenna) : 20mA Mag. E( Dipole antenna) : 8uA

8 The EH field Do you know the wave impedance, the E/H field? Wave impedance ( Zwave) pi 100 Electric Near field Far field Magnetic -The Basic EH field -Near & Far field -Low & High Impedance You go back to the E/H field, if you are in a difficult situation /(2pi) Distance per wavelength ( r / lambda)

9 Noise issues in a PC Board If you can see noise sources, please set EMI filters near to noise sources. EMI EMI Filters Filters If you can t, please set EMI filters at victim chips & drivers of cables. Shields Shields And please set a shielding plate over the PC Board.

10 What is a EMI filter? EMI EMI Filters Filters Noise level Signal Noise level Signal Frequency Frequency -Select target signals, a cut off frequency. -The key is how to select the best filter. -Can you search the specification of EMI filters? Insertion loss Impedance Attenuation (s21) Impedance What is this? Noise 3m, 10m

11 Filters convert from noise to heat Do you know a bead inductor? A bead change high frequency noise to heat. A bead temp. (1MHz) A bead temp. (100MHz) Low frequencies: Low impedance Low temperature A ferrite bead filter High frequencies: High impedance High temperature R:0.0014ohm L:0.126uH Freq:1MHz σ:100 S/m Real.Mu:400 Imag.Mu:-30 A bead filter s impedance converts from High frequency noise to heat, you can analyze impedance and heat. R:0.11ohm L:0.0137uH Freq:100MHz σ:100 S/m Real.Mu:30 Imag.Mu:-100 Maxwell 3D + ephysics

12 The Impedance of Capacitors A shunt capacitor Port1 0.1nF 0 100pF 1000pF 0.01uF 0.1uF A Tuning function Sweeping of Capacitor s values by Ansoft Designer A High frequency makes a low impedance. A Large value of capacitors makes a low impedance.

13 The Impedance of Inductors Inductors or choke coils Port1 100uH 0.1uH 10uH 0 1uH 0.1uH A Tuning function Sweeping of Inductor s values by Ansoft Designer A High frequency makes a high impedance. A Large value of inductors makes a high impedance.

14 Parasitic inductance of Capacitors 10nH Impedance 1nH 0.1nH Port1 0.5*Ind 0.1uF 0.5*Ind 0 Parasitic inductance of Capacitors are called ESL. A ESL makes a self-resonant frequency, and make The high impedance in the high frequency band. A large ESL makes a self-resonant frequency low.

15 The role of capacitors Coupling capacitors Separates circuits with DC, couples circuits with AC. Bypass capacitors Bypass unnecessary signals to GND for transistors. Decoupling capacitors Sets between power lines and GND lines for prevent voltage changing. Today s EMC engineers have seen Power ground issues are most important for EMC problems, Decoupling capacitors have became the major role.

16 Is this a capacitor? Capacitor + ESL 100 x 100 mm 1mm Capacitor - A huge size plate capacitor. - The most simple Power ground model - The size of plates have EMC problems. FR4 epoxy

17 Power & GND plates, too. We can see these plates seem the same as previous huge plates. And we can see these plates have some self-resonant frequencies.

18 Is self-resonant frequencies serious? Power PC board Power 1 PC board Self-resonance At self-resonant frequency 0.01 We get high level noise.

19 Plate resonant analysis SIwave V3 -PC board power integrity analysis -PC board signal integrity analysis -Far field emission test analysis -Spice model, S parameter model extraction A story: -Analyze plate resonant frequencies. -Extract ports impedance on plates. -Search between resonant modes and the impedance. -And.. 100mm x 100mm copper plates 1mm width FR4 epoxy substrate

20 Plate resonances & Impedance plots Prove points on a plate corner Center A resonant frequency table by SIwave Ten seconds analysis Resonant frequencies Peak points of impedance Impedance plots by SIwave V3

21 714MHz resonance Voltage variation between power and ground planes 2 different modes rise at same frequency. The voltage of the center point doesn t change.

22 1.01GHz resonance The voltage of the center point doesn t change.

23 1.43GHz resonance The center point makes max. changing voltage. Both impedance are high at 1.43GHz

24 1.60GHz resonance The voltage of the center point doesn t change.

25 2.03GHz resonance Some modes are born on parallel plates.

26 Does a resonance make noise? Prove position ( 45.0mm, 45.0mm ) Impedance plot The self-resonance analysis takes only ten seconds. We can get a noise level (Mag.E) at 3m distance by SIwave V3 easily!!

27 Mag.E noise level 3m V Voltage source : max. voltage changing 0.1v The Input impedance : 0.05ohm 3m Radiation pattern Mag.E Emission test 3m

28 Mag.E noise level 3m V Voltage source : max. voltage changing 0.1v The Input impedance : 50ohm If we change input imp. from 0.05 to 50 ohm, peak points of change. 3m Mag.E We can understand the relation between noise levels and Serial or Parallel resonance.

29 Summary (1) Capacitors and EMI filters are used for EMI/EMC problems. Focused to Power and Ground lines for EMI/EMC. Resonance analyses are usual. Impedance plots are very useful. Emission test plots are more useful for EMI/EMC. A 10 seconds analysis tool. Let s use both impedance plots and Emission test. Impedance plots and Emission test@3m, 10m

30 Next step: A real PC board Layers: 6 Nets: mm x 170mm Let s try to EMC analysis for a real PC board.

31 A design flow of PC boards A traditional design flow Places main ICs Checks In/Out spec. Today s design flow Checks of In/Out spec. Places Power & GND Selects significant signals Saves areas for bus lines Places main ICs Saves passes of bus lines Places parts Search signal passes Place parts Search signal passes Assign Power lines & GND planes to free spaces Saves areas for troubles and revision-up Because of some difficult EMI/EMC issues, the Power and Grounding design has become the leading role.

32 A proposal from Ansoft Your established design flow Additional environment by Ansoft Power Power & GND GND design design by by Cadence Cadence or or Mentor Mentor A detail detail PC PC board board design design SI SI analysis analysis AnsoftLinks AnsoftLinks AnsoftLinks AnsoftLinks.anf Partitioning.anf SI SI analyses analyses by by Q3D/HFSS Q3D/HFSS P & G analyses analyses by by SIwave SIwave Analyze P & G for EMI/EMC Resonance freq. A whole PC board.anf Trial Trial productions productions Testing Testing Spice models, S parameters T line models Ansoft support your design flow from the first step to the last Testing step. Virtual Virtual Testing Testing by by SIwave SIwave Decoupling cap. Virtual Emission

33 A design flow of Ansoft PC board s CAD data by Cadence, Mentor AnsoftLinks AnsoftLinks Power Integrity & Signal Integrity Signal Integrity Partitioning and cutting Extracting Models for SI SIwave SIwave V3 V3 Q3D Q3D Extractor Extractor HFSS HFSS V10 V10 Virtual Virtual EMC EMC testing testing LCR extraction S parameter extraction T line s Spice & S parameters AD AD / / Nexxim Nexxim Simplorer Simplorer Cadence Cadence Mentor Mentor

34 An.anf file from Cadence Allegro 6 Layers, 468 nets 210mm x 170mm AnsoftLinks If you select a whole PC board, You can get a model PI & SI. If you partition, you can get 3d models for SI analyses. SIwave Q3D Extractor / HFSS

35 LCR chips on PC boards LCR chips are placed automatically by Cadence Allegro. You can set LCR chips on a PC board.

36 Some good collaborations Noise suppression devices Capacitors Inductors Resisters EMI filters Good collaboration Murata Panasonic TDK Taiyo Yuden

37 Plane resonant analyses by SIwave Calculating time ( about 30s) 30 seconds analysis Resonant frequency table ( 100MHz< Resonant Freq. ) Next step, let s extract the impedance of a PC board.

38 Set ports on a PC board Port1 Port2 2 ports are set on the PC board.

39 Port S parameters We can get S parameters.

40 A port Impedance Port1 Port2 Impedance Z (ohm)

41 The Port1 impedance plot

42 Set a noise source as a virtual noise. You can set a voltage or current source as a noise source.

43 410MHz voltage changing A Voltage source

44 510MHz voltage changing

45 690MHz voltage changing

46 850MHz voltage changing

47 Emission test 3m 410MHz 510MHz Noise level Mag.E (dbuv/m)

48 Reduce noise <500MHz 410MHz 510MHz Set two decoupling capacitors (100pF) for noise suppression. Parts No. : Panasonic 1608 ceramic 100pF ECJ1VC1H101

49 Can we get a good results? Port1, Port2 impedance plots

50 30 seconds later Noise level Mag.E (dbuv/m) 300MHz 355MHz You can get noise level plots immediately.

51 300MHz voltage changing

52 355MHz voltage changing

53 795MHz voltage changing

54 One more capacitor Second try: Add a 100pF First try: 100pF capacitor x 2 Parts No. : Panasonic 1608 ceramic 100pF ECJ1VC1H101

55 Impedance plots A peak point is moved from 355MHz to 280MHz

56 Low frequency noise

57 280MHz voltage Third try: Change a value of an added capacitor from 100pF to 10,000pF. Parts No. : Panasonic 1608 ceramic 10,000pF ECJ1VB1H103

58 A Good result

59 Noise level Mag.E (dbuv/m)

60 555MHz voltage changing We set capacitors on the corner of a PC board, but

61 Your design flow Global characteristic of a PC board Power & ground layout Resonant analysis 10 seconds Detail signal analyses and parameter extraction Detail signals Layout SI analysis Spice, S parameters Testing Noise suppression and Emission Test Virtual Testing 30 seconds +30 seconds

62 Summary (2) Resonant frequency Impedance plots Noise level plots 30 seconds analysis Screening Power & Ground of PC board s Virtual decoupling for EMI/EMC Include your design flow A new testing environment A virtual testing You can establish new virtual testing environment by Impedance & Noise level plots.

63 We can spread these results At last, we have acquired a great analysis tool for a whole PC board. A whole PC board Impedance The whole PC board analysis is important for EMI/EMC. And we want to use more widely. Can we analyze the whole vehicle with the whole PC board? Noise level Let s try!!

64 New linkage functions A noise analysis by SIwave Ansoft has developed new linkage functions. A excitation source SIwave to HFSS HFSS to HFSS A ECU analysis by HFSS A EM analysis by HFSS

65 Far field analysis by SIwave Noise level Mag.E plots A Voltage source Select Solve Far Field, You can solve far field.

66 Noise sources by SIwave A PC board analysis by SIwave SIwave to HFSS A excitation source of HFSS The far and near field by SIwave becomes a excitation source of HFSS.

67 We can set noise source easily. Setting a boundary condition A Noise source by SIwave HFSS environment

68 Use the results of SIwave Assign a result of a SIwave analysis

69 A 310MHz noise source Mesh: 187,137 CPU time: 14m6s (Pentium M, 2GHz) A PC board by SIwave A Impedance peak point : 310MHz

70 A 310MHz noise source (XY plane) A PC board by SIwave

71 500MHz noise source Mesh: 730,133 CPU time: 3h20m (Pentium M, 2GHz)

72 Set a noise source in a car room Mesh: 254,966 CPU time: 34m41s (Pentium M, 2GHz)

73 A noise source and a cable A cable

74 Mag. E levels on the cable Noise levels of near field of a cable ( Cable termination: 50ohm, 1kohm) A cable A cable 50 1K ohm 50 ohm 50 ohm This plots show the relation of Mag.E field and terminations of cables. This examples have 50ohm termination and 1kohm termination. Mag.E level is changed by differences of terminations. We can get some interesting data from these entire analyses including PC boards and automotive vehicles.

75 We can do. We can use the results from SIwave. We can set these results as noise sources on HFSS. We can cover critical PCB s and entire vehicles. We can analyze EMI/EMC issues of entire automotive vehicles and PCB s. We can challenge the next step of EMI/EMC world. We will propose the progressive design flow for you. You will find a ray of hope for the future with Ansoft.

76 References [1] Y. Sakamoto, Noise suppression devices and EMC designs Kogyochosa-kai 2005 Jan. [2] O.Fujiwara, Correspondence between Frequency Characteristics of Radiated Emission and Input Impedance of Power-Ground planes of PCB Singakuron(B) Vol.J86-B No.8 pp Aug. [3] N. Shibuya, Crosstalk Noise Analysis of Wiring on the Printed Circuit Board Shingakuron(B) Vol1.J68-B, No.9, pp [4] K. Sekine, The thermal and frequency dependent analysis of a ferrite bead filter by Maxwell 3D & ephysics A Maxwell 3D & ephysics training material Ansoft Japan K.K Aug. [5] Panasonic Industrial Solutions Passive & Electromechanical _e/passive_electromech_e.html