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From traditional vehicle to pure electric vehicle and then to range-extended electric vehicle (ReEV), the electrification of vehicle has caused a great change in NVH characteristics. ReEV has the most complex noise and vibration problems because it behaves both like traditional vehicle and pure electric vehicle. In addition, it has its own specific NVH characteristics. Firstly, internal combustion engine drives the generator rather than drives the vehicle. Due to the structure and load change, auxiliary power unit (APU) performs specific NVH characteristics. In addition, the pure electric mode will have the high frequency noise generated from the driveline because the noise couldn't be masked by the engine. In system level, unexpected and confusing sound in passenger compartment may affect the driver's comfort and judgments. Therefore, more and more attentions on these issues should be paid. NVH study and improvement methods on ReEV are emphasized.

In course of the electrification of vehicle's powertrain, one of the vital problems we've been faced with is the limitation of the vehicle's driving range due to the capacity of currently available batteries. Therefore, range-extended electric vehicle (ReEV) concept has become one of the most promising transitory technologies to compensate this defect. Electric vehicle is supposed to be quiet and comfortable for the customers. However, some annoying sound derived from powertrain and accessories must be reduced or eliminated to meet this requirement. Accessory NVH has an important contribution to ReEV's NVH performance. If it is not well handled, poor vibration and noise may appear. This paper focuses on accessories' NVH performance in ReEV including the NVH problems from steering pump, vacuum pump and AC compressor.

In recent years, electric vehicle and hybrid vehicle are either on the market or under intensive research and development (R&D). Since the concept of auxiliary power unit (APU) was brought into the automotive industry, the range-extended electric vehicle (ReEV) has become the favor of the worldwide manufacturers. Normally, the APU starts and stops more frequently in response to the control strategy compared with traditional vehicles, which will affect the ride comfort of passengers. Thus, APU start-stop NVH refinement is an important aspect of ReEV R&D. In this paper, a subjective evaluation on a ReEV was performed to quickly diagnose NVH issues firstly. Based on subjective results, the NVH experiment in a semi-anechoic room was carried out to troubleshoot these issues. The accelerations of the APU mounts, the seat track and the steering wheel as well as interior noise level were acquired and analyzed.