Analytical Framework of Gearbox Monitoring Based on the Electro-mechanical Coupling Mechanism

Along with the development of the Hybrid Electric Vehicles (HEVs), the permanent magnetic synchronous motor (PMSM) and the planetary gearbox is widely used because of its high power density. There is much significant electro-mechanical coupling phenomenon in the mechanical installations. The aim of this paper is the analytical study of a planetary gearbox by using the stator current signature analysis in the PMSM based on the electro-mechanical coupling mechanism. This paper proposes a mathematical framework based on the electro-mechanical coupling model of the PMSM-planetary gearbox system, considering the load torque oscillation and the time-varying mesh stiffness. The model simulation result shows that from the mathematical framework, the load torque oscillation frequency and the time-varying mesh stiffness frequency can be predicted through the current frequency. The proposed mathematical model is verified by the model simulation. And a test-bed based on a 60 kW three-phase PMSM connected to a planetary gearbox has been used. Fourier transform is applied to the demodulated torque signal and current signal for denoising and removing the intervening neighbouring features.