An Approach for Practical Use of Common-Mode Noise Reduction Technique for In-Vehicle Electronic Equipment

Takanori UNO  Kouji ICHIKAWA  Yuichi MABUCHI  Atsushi NAKAMURA  Yuji OKAZAKI  Hideki ASAI  

IEICE TRANSACTIONS on Communications   Vol.E93-B   No.7   pp.1788-1796
Publication Date: 2010/07/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E93.B.1788
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Advanced Electromagnetic Compatibility Technology in Conjunction with Main Topics of EMC'09/Kyoto)
Category: Transmission Lines and Cables
EMI,  common-mode current,  optimization algorithm,  ECU,  

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In this paper, we studied the use of common-mode noise reduction technique for in-vehicle electronic equipment in an actual instrument design. We have improved the circuit model of the common-mode noise that flows to the wire harness to add the effect of a bypass capacitor located near the LSI. We analyzed the improved circuit model using a circuit simulator and verified the effectiveness of the noise reduction condition derived from the circuit model. It was also confirmed that offsetting the impedance mismatch in the PCB section requires to make a circuit constant larger than that necessary for doing the impedance mismatch in the LSI section. An evaluation circuit board comprising an automotive microcomputer was prototyped to experiment on the common-mode noise reduction effect of the board. The experimental results showed the noise reduction effect of the board. The experimental results also revealed that the degree of impedance mismatch in the LSI section can be estimated by using a PCB having a known impedance. We further inquired into the optimization of impedance parameters, which is difficult for actual products at present. To satisfy the noise reduction condition composed of numerous parameters, we proposed a design method using an optimization algorithm and an electromagnetic field simulator, and confirmed its effectiveness.