Effects of carrier frequency modulation control on the unpleasantness of inverter noise

Takuma Kasori･Masahiko Kondo･Masao Yamaguchi･Takeshi Toi (Chuo University)

Inverter noise consists of multiple pure-tone components generated by the carrier frequency and its sidebands. In recent years, carrier frequency modulation has been used to spread these pure-tone components and improve masking effects. In this study, the effects of modulation parameters, such as modulation width, on unpleasantness were quantitatively evaluated, and effective modulation conditions for reducing unpleasantness were clarified.

Adaptive Update of a Backlash Estimation Observer Based on Online Backlash-Angle Identification for Vibration Suppression in EV Powertrains

Manato Kawasaki･Noboru Sakamoto･Akira Nakashima (Nanzan University)

We propose a method to suppress vibrations in EV powertrains by online identification of the gear backlash angle and adaptive updating of a backlash estimation observer via feedback of the identified value. Numerical simulations demonstrate the effectiveness of the proposed method and provide a comparison with a conventional observer under parameter variations. The influence of identification errors on vibration estimation is also discussed.

Measurement of rattle behavior and backlash modeling in automatic transmissions

Seijun Morita･Kensuke Imanishi･Kotaro Suzuki･Ryu Chikasue･Yu Chen (Mazda)

In automatic transmissions (ATs), expanding the lock-up area or adopting a torque-converter-less structure can improve environmental and driving performance, but it also increases the risk of rattle noise. By measuring the angular velocities both sides of the backlash inside the AT, the rattle occurrence state for each driving condition were identified. Based on measurement results, the backlash model capable of reproducing backlash collision velocities was constructed.

Motor Bearing Knocking in Electric Powertrains
-(Part I - Elucidation of the Mechanism)-

Shinpei Kondo･Daisuke Kobayashi･Tsuyoshi Kozima･Hiroshi Matsuo (Nissan Motor)･Takanori Nakatani (Nissan Automotive Technology)

Although abnormal noise in electric powertrains is easily detected in electric vehicles, its underlying mechanism remains unclear. This paper focuses on knocking noise from motor bearings and, based on dynamic simulations and validation on an actual powertrain, shows that the knocking phenomenon occurs when the radial runout trajectory of the motor shaft, tilted by gear reaction forces, passes through the bearing's radial clearance.

Motor Bearing Knocking in Electric Powertrains
-(Part II - Development of the Design Method)-

Daisuke Kobayashi･Shinpei Kondo･Takayuki Asai･Shiro Kono (Nissan Motor)

Based on the shaft dynamic behavior mechanism of the electric powertrain clarified in the first report, this study proposes a design process for noise suppression through shaft dynamic behavior control. Shaft dynamic behavior analysis is incorporated as an evaluation method applicable to component design, enabling the quantitative prediction of abnormal noise. This approach enables a superior balance among cost, efficiency, and NVH performance in electric powertrains.