Vehicle-level Analysis Technique for EMC Design of Automotive Inverters

Hiroki Funato, Dr. Eng. Jia Li, Dr. Eng. Masayoshi Takahashi, Dr. Eng. Isao Hoda Hideyuki Sakamoto Ryuichi Saito OVERVIEW: To ensure vehicle safety and comfort, there is a need to minimize interference due to electromagnetic noise from automotive electronics. While automotive manufacturers have stipulated EMC standards for this purpose that component suppliers are obliged to comply with, there are cases when additional measures are needed to satisfy EMC requirements for the vehicle as a whole even though its individual components comply with the EMC standards, as the behavior of electromagnetic noise varies depending upon the installation conditions. This happens because the amount of noise generated changes when the electronics components are installed onboard. In response, Hitachi has developed a vehicle-level analysis technique that can predict electromagnetic noise for the completed car in which the electronic components are installed, thereby enabling EMC countermeasures to be incorporated into the design at an upstream design level, rather than added reactively. To enable the technique to predict the level of noise with sufficient accuracy for use in design (within ±12 dB), it splits the vehicle analysis into three separate parts in order to reduce the dynamic range that each one needs to deal with, thereby making it possible for the full analysis to deal with the wide dynamic range in the level of electromagnetic noise detected by a vehicle-mounted antenna, from the drivetrain inverter with a high power output (kW) down to tiny μW-level radiation. By adopting this approach, Hitachi believes it can successfully perform EMC design for the completed vehicle at the component design stage.