A Novel Compensator for Eliminating DC Magnetizing Current Bias in Hybrid Modulated Dual Active Bridge Converters

Abstract

This paper proposes a compensator to eliminate the DC bias of inductor current. This method utilizes an average-current sensing technique to detect the DC bias of inductor current. A small signal model of the DC bias compensation loop is derived. It is shown that the DC bias has a one-pole relationship with the duty cycle of the left side leading lag. By considering the pole produced by the dual active bridge (DAB) converter and the pole produced by the average-current sensing module, a one-pole-one-zero digital compensation method is given. By using this method, the DC bias is eliminated, and the stability of the compensation loop is ensured. The performance of the proposed compensator is verified with a 1.2-kW DAB converter prototype.

A Fluxgate-Based Current Sensor for DC Bias Elimination in a Dual Active Bridge Converter

“…It is possible that the winding currents contain DC components whose MMFs cancel in the core. In [16]- [22], the DC component of magnetizing current was eliminated by controlling the primary side duty cycle. However, the iron-cored inductor L on this side for power transfer control may still suffer from saturation and cause the control to be unstable.…”