Voltage signal analysis is promising for fault diagnosis of planetary gearbox in electro-mechanical drivetrain. Comparing with the commonly-used vibration signal analysis, it has advantages of convenient measurement and relatively simple frequency structure. In this work, the amplitude modulation and frequency modulation effects of local planetary gearbox fault on the voltage signal of permanent magnet synchronous generator is analysed by electromechanical coupling dynamics analysis. The analytical signal model of the voltage signal is constructed, and the distribution of fault signatures on the frequency spectrum are explicitly derived. Laboratory tests on a planetary gearbox test rig are conducted, and the real-world measured voltage signals of permanent magnet synchronous generator are analyzed. The results validate the derived fault signatures, and local defects on the planet gear is successfully diagnosed.

voltage,planetary gearboxes,fault diagnosis