Presentation Information
[B-4-34]Changes in Conducted Emissions Caused by High-Voltage Automotive Auxiliary Battery Systems
〇Hiroyuki Takatsuji1, Tatsuya Hosotani1, Jun Imaoka2, Masayoshi Yamamoto2 (1. Murata Manufacturing, 2. Nagoya Univ.)
Keywords:
DC-DC Converter,Conducter Emission,Common mode noise,48V
The transition from conventional 12-V auxiliary batteries to 48-V systems is being considered for automotive applications to accommodate increasing electrical power demand. However, the influence of higher input voltage on conducted emissions has not been sufficiently clarified. This paper investigates the conducted emissions of a 2.2-MHz buck converter used as an automotive primary power supply by comparing 12-V and 48-V operating conditions. Conducted emissions were measured in accordance with CISPR 25, and propagation mode analysis was performed. The results show that common-mode noise dominates in the FM radio frequency band and increases by approximately 8 dB when the input voltage is increased from 12 V to 48 V. To identify the dominant factor, the effects of input voltage, output voltage, and output power were compared independently. The results indicate that the increase in input voltage is the primary cause of the increased common-mode noise. Waveform analysis further suggests that the increase in the switching-node voltage slew rate (dV/dt) under 48-V operation is the main mechanism responsible for the increased conducted emissions.