An asymmetrical half bridge DC-DC converter: close loop design in frequency domain

In this paper, the small signal model analysis of an asymmetrical half-bridge DC-DC converter (AHBC) operating in the continuous conduction mode (CCM) is presented. The influence of the non-ideal components to the system performance is discussed. Based on the small signal model, the close loop feedback is designed in the frequency domain for a PI controller and a lead-lag controller. The design criteria for the close loop feedback are described and a clear design process for the feedback compensator is presented. How to achieve the optimum bandwidth and phase margin under the influence of the complicated system structure is investigated. The close loop system load dynamic response from a 12 V/4 A experiment circuit is obtained.