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A hybrid electric vehicle (HEV) will start the engine which drives its motor to charge the battery even at idle whenever the battery power is detected to be insufficient. The activation of idle battery charging could lead to serious NVH problems if powertrain parameters are not designed or calibrated properly. This work is focused on a noise issue encountered during idle charging for a specific prototype vehicle, and investigates control strategies to contain the noise level. Based on basic principles of automobile vibration and noise control along with the specific characteristics of the hybrid vehicle architecture, this work analyzes and elucidates methods of the engine idle charging noise control from the perspectives of powertrain modal alignment, idle speed optimization, and electric motor control algorithm.

Noise excitation sources are different between electric vehicles and conventional vehicles due to their distinct propulsion system architecture. This work focuses on an interior noise contribution analysis by experimental measurements and synthesis approach using a methodology established based on the principle of noise path analysis. The obtained results show that the structure-borne noise from the tire-road excitation acts as a major contributor to the overall interior noise level, and the structure-borne noise from the power plant system contributes noticeably as well, whereas contributions from the electric motor and tire are relatively insignificant.