Online open-switch fault diagnosis method in single-phase PWM rectifiers

On the basis of sampling theory, an online open-switch fault diagnosis and location method for single-phase pulse-width modulation rectifiers applied in electric railway traction is presented. First, on the basis of analysing the features of the post-fault line current under instantaneous current control strategy at low switching frequency, two specific pulse sequences for sampling line current are generated via the modulation. Then, the DC component of the sampled signal, which is easy to use for diagnostic decision, is obtained through filters. Experimental results are presented to illustrate the validity of the proposed scheme.