Fault diagnosis of a single-phase inverter using the magnetic field waveform near the output inductor

A low-cost diagnostic method for the single-phase inverter is proposed in this paper. A low-cost fabricated loop magnetic filed probe is used to detect the magnetic field near the output inductor of the inverter; the measured waveform is utilized as the diagnostic criterion, and is processed by the simple peak detector and comparators. With the proposed circuit, the open-circuit faults of the inverter can be diagnosed during the soft-start period. The voltage sensor is needless; the circuit is isolated from the power stage naturally and the diagnostic system is low-cost but effectual. The waveform analysis, diagnostic circuit design and the experimental results are presented in this paper.