公开(公告)号：US20190058428A1

公开(公告)日：2019-02-21

申请号：US15998538

申请日：2018-08-16

Applicant: ALSTOM Transport Technologies

Inventor： Davide BARLINI

IPC: H02P21/16 ,  H02P27/08 ,  H02P21/22 ,  G01M13/04 ,  G01R31/34

Abstract: The present invention relates to a method for determining a state of a bearing of a three phase electric machine, the electric machine having a rotor, which is supported by the bearing, the electric machine being connected to a three phase inverter for supplying the electric machine with electric power, the three phase inverter being controlled to apply a pulse width modulation with a predefined scheme to create three phase currents, the method comprises: —determining a first phase current provided to the electric machine; —determining a second phase current provided to the electric machine, the second phase current being different to the first phase current; —determining the power spectral density of the park's vector based on the first phase current and the second phase current; —determining an amplitude of the power at a predefined frequency of the power spectral density, wherein the predefined frequency depends on the rotational speed of the rotor and the scheme of the pulse width modulation; —comparing the amplitude of the power at the predefined frequency with a predefined power value; and —determining, based on the comparison, whether a failure of the bearing has occurred or the bearing is degraded.