Experimental investigation of the noise, vibration and harshness performances of a range-extended electric vehicle

The electrification of vehicles has caused a great change in the characteristics of noise, vibration and harshness. A range-extended electric vehicle has complicated noise and vibration problems because it behaves both like a traditional vehicle and like a battery electric vehicle as well as having its own specific noise, vibration and harshness properties. Therefore, increasing attention should be paid to these issues. This paper is intended as a contribution to the current research on the noise, vibration and harshness of a range-extended electric vehicle. The electric driveline, the auxiliary power unit and the accessories, including the power steering pump, the electric vacuum pump and the air conditioner compressor, are tested and their noise, vibration and harshness performances are analysed. The results indicate that the high-frequency noise of the electric driveline and the vibrations of the auxiliary power unit and the air conditioner compressor are crucial noise, vibration and harshness issues of a range-extended electric vehicle. Some improvement methods are implemented or proposed for better comfort in the passenger compartment. Application of a material which is sound insulating and sound absorbing proved to be an effective countermeasure. The design and refinement of a vibration isolation system for the auxiliary power unit and the air conditioner compressor are of great importance. A reduction in the low-frequency torsional resonance of the auxiliary power unit shaft during a start–stop process is a new problem compared with that of a conventional engine. It is necessary to find a well-balanced compromise between the expected acoustic feedback and the power demand.