A sensor for balancing flux in converters with a high-frequency transformer link

A method is introduced for measuring a selected flux threshold below saturation, by means of a pickup winding. The method is illustrated using a block-wave oscillator and involves placing a pickup winding in a square indentation in the center leg of an E-core. Incorporating an air gap, a high-reluctance path is created at the area of the indentation. The remaining area saturates first and forces flux through the high-reluctance path, which induces a voltage on the pickup winding. The method was tested experimentally, and a proposed mathematical model was used to simulate the magnetic behavior of the sensor. Experimental and simulated results are presented and compared to verify the discussed operation. Although similar strategies have been reported previously, the significance of the sensor introduced in this paper is that detection takes place before saturation occurs and the sensor is integrated in the core.