IGBT stuck-open fault diagnosis method for three-phase inverter bridge of frequency converter

An IGBT (insulated-gate bipolar transistor) stuck-open fault diagnosis method for a three-phase inverter bridge of a frequency converter belongs to the technical field of IGBT fault diagnosis of three-phase inverter bridges and solves problem that misdiagnosis is caused in instant load or instant unload when stuck-open fault of IGBTs of an inverter bridge is determined through the Park vector method. The method comprises the following steps: firstly, three phase currents ia, ib and ic of a motor stator used for speed regulation and controlled by the frequency converter are collected; secondly, the three phase currents ia, ib and ic are transformed through discrete Fourier transform to obtain cosine component aj, k and sine component bj, k of direct current component amplitude and fundamental component amplitude of the three phase currents ia, ib and ic; thirdly, the direct current component amplitude is normalized through the fundamental component amplitude to obtain a direct current component normalization value hj; fourthly, a fault phrase of the three-phase inverter bridge is determined according to the direct current component normalization value hj; and then whether the faultphrase is in an upper transistor or a lower transistor is determined. The invention is suitable for fault diagnosis of three-phase inverter bridges.