Power converter having a differential determination with secondary current sensor

Abstract

A power converter including a transformer (Tr) with a primary and a secondary, and a capacitor (Cr) and an inductor (Lr) serially connected with the primary of the transformer. The capacitor, the inductor and a magnetizing inductor (Lm) of the transformer form an LLC resonant circuit. The power converter further including a first current sensor (CT) and a second current sensor (CT). The first current sensor including the inductor and is configured to sense, via the inductor, a current passing through the primary of the transformer. The second current sensor including the primary and is configured to sense, via the primary, a current passing through the magnetizing inductor of the transformer. A current passing through the secondary is determined from a difference obtained based on the sensed current passing through the primary of the transformer and the sensed current passing through the magnetizing inductor. The power converter has the advantage that it is possible to provide an accurate sensed current at a low cost without load limitation, and it is also possible to perform a cycle-by-cycle protection function since a load waveform can be restored. In addition, another power converter is also provided, which has a structure for reducing power circulation among parallel windings (Wa, Wb) of the transformer.