Analysis of longitudinal-vertical coupling vibration of four hub motors driven electric vehicle under unsteady condition

Qiongyao Li, Conggan Ma, Nic Zhang, Yue Guo, Michele Degano, Chris Gerada, Shengsen Zhou, Yuansheng An

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Abstract

The influence of hub motor unbalanced magnetic force (UMF) on the vibration of electric vehicle under steady state conditions has been known, but under unsteady conditions, the hub motor UMF will change with the vehicle operation condition, and there would exist complex coupling vibration for the hub motors driven electric vehicle. Here, the longitudinal-vertical coupling dynamics of the four hub motors driven electric vehicle under unsteady condition is studied. Integrating the motor electromagnetic excitation and electric vehicle dynamics, a longitudinal-vertical coupling dynamics model of the four hub motors driven electric vehicle is established. Based on the variable switching frequency field-oriented control model, analytical model of the UMFs acting on the motor stator and rotor parts under unsteady condition are developed. For model validation, a four hub motors driven electric vehicle has been tested, the accuracy of the longitudinal-vertical coupling dynamics model established in this paper was verified. Then, longitudinal-vertical coupling vibration characteristics of the four hub motors driven electric vehicle under road excitation and coupling excitation are analyzed. The results show that the longitudinal and vertical movement of the four hub motors driven electric vehicle is coupled by hub motor. In addition, under unsteady condition, the motor UMFs will cause vertical vibration of the electric vehicle body and hub motor stator, the vibration shows order characteristics including low order harmonic hfc and inverter switching frequency sideband harmonic k1fs±k2fc (fc = pn/60, fs is inverter switching frequency, k1 and k2 are positive integers, p is the number of pole pairs and n is motor speed.). The motor electromagnetic torque will cause longitudinal vibration of the electric vehicle body, the vibration shows order characteristics including harmonics fs±3fc and 2fs. The main harmonic of vehicle body pitch angle acceleration is 2fs.

Original languageEnglish
Number of pages12
JournalProceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering
Early online date8 Mar 2024
DOIs
Publication statusE-pub ahead of print - 8 Mar 2024

Keywords

  • Four hub motors driven electric vehicle
  • longitudinal-vertical coupling dynamics
  • permanent magnet synchronous motor
  • unbalanced magnetic forces (UMFs)
  • unsteady condition

ASJC Scopus subject areas

  • Aerospace Engineering
  • Mechanical Engineering

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