Feasibility Study on a Novel Robust Current-mode Method

Abstract

This paper presents the feasibility study of a novel robust current-mode (CM) control method to regulate the output voltage of a Flyback converter operating in Quasi-resonant (QR) mode or Discontinuous Conduction Mode (DCM). Unlike the traditional CM technique, in the proposed solution the control variable of the loop is proportional to the dc output current. Therefore, the dc output current can be monitored from the primary side without current-sensing components or dedicated circuitry, and with a precision that is little affected by the tolerance of the parameters of the power stage. Also, unlike average current mode (ACM) control schemes used to regulate the output current, in which the averaging slows down the dynamics of the converter, this new method still provides the same excellent dynamic response as the traditional CM. In this paper a theoretical analysis of the new method is provided, showing the operating principle, the steady-state equations, and the small-signal analysis. The main nonidealities are discussed too. Finally, the simulation results will demonstrate feasibility and benefits of the method.