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This paper proposes a detection method of open-circuit fault of insulated-gate bipolar transistor in the voltage source inverters. The magnetic field signal at the DC bus of the inverter is collected and analysed to detect the fault. First, the simulation is developed for a voltage source inverter-fed induction machine drive which operates in healthy state and single switch open-circuit conditions. The faulty characteristic frequencies in the spectrum of DC-link current signal are derived on the basis of the power balance analysis through the inverter. Second, laboratory tests are implemented with a test bed of voltage source inverter-based induction machine drive in which a Hall sensor suited for the geometry complexity of the DC bus structure is utilized for measuring the magnetic field signal, which can be considered as an image of the simulated DC-link current. The fast Fourier transform of the magnetic field signal shows sharp increases in spectrum amplitude at the fundamental, second-order and third-order harmonics that they can be used as the indication to detect the fault. The approach using proposed signal offers several advantages such as single-sensor requirement, non-invasive and less costly device. [ABSTRACT FROM AUTHOR]