EFFECTS OF FIRING ANGLE IMBALANCE ON 12-PULSE RECTIFIERS WITH INTERPHASE TRANSFORMERS

Firing angle or source imbalances between 6-pulse bridges comprising a 12-pulse rectifier lead to current imbalance, due to the finite magne tizing inductance of the interphase transformer, The magnitude of the imbalance is limited by the negative feedback produced by load regulat ion of the 6-pulse groups. This paper uses both an averaged model and a piecewise-linear simulation to obtain a quantitative understanding o f this effect. The averaged model is used to predict steady-state curr ent shifts and transient behavior, The piecewise-linear model of the s ystem is then used to verify and extend the results via computer simul ation. It is shown that the current imbalance can be accurately predic ted by the averaged model, making the model suitable for both feedback control and interphase transformer design.