Novel design technique for reducing common-mode current on wire harness connected to ECUs

A key parameter that controls common-mode cur- rent on the cable connected to electronic control units (ECUs) is investigated. Supply currents for the CPU on ECUs and parasitic inductance / capacitance of supply traces on printed circuit boards (PCBs) generate common-mode current on the cable. We found the amount of common-mode current can be reduced sensitively by adjusting the balance of parasitic inductance / capacitance. The new approach proposed in this paper allows minimizing the common-mode current and suppress the radiation less than the currently achievable level. This technique is proven experimentally with evaluation boards and the influence of these parameters on common-mode current is confirmed by our simulation technique. I. INTRODUCTION Nowadays, a driving speed of LSI is getting faster and it is equipped on electronic device denser than past one. According to these situations, electromagnetic radiation from electronic devices becomes larger and it gives harmful influence on electronic devices such as jamming of radio communication or miss action of its circuits. Especially in automobile, EMI/EMC becomes very serious problem because many electronic de- vices are equipped together with a radio in a car. The origin of electromagnetic radiation emitted from electronic device is voltage fluctuation and high frequency current that are exited when LIS is driving. These voltage fluctuation and high fre- quency current drive printed circuit boards (PCBs), their frame and cable attached to them as antennas and electromagnetic wave is radiated from them. At VHF (30∼300MHz) frequency