A Class of Control Strategies Based on Bias Current Decouple for High Precision Current Converter

In order to avoid zero-crossing distortion caused by blanking time, dual buck topology has received more and more attention. The continuous current mode (CCM) of filter inductor can be maintained by injecting bias current, which can eliminate zero-crossing distortion. The existing current decoupling control strategy of dual buck full bridge converter (DBFBC) is realized by independent control of four main switches and the driving signals of switches are independent and have no phase constraints. The proposed strategies are presented with only two sets of driving signals to achieve low harmonic distortion, which can reduce the complexity of the system and potentially contribute to circuit topology design. The correlation of switching signals and principle of the control strategies are analyzed by establishing the state-space average model of the topology. Moreover, the current characteristics of filter capacitor is considered, which can provide mechanism analysis for the design of filter circuit. The experimental results are presented and high precision of output current is achieved.