IMPROVED FIXED CURRENT-MODE CONTROLLER IN QUADRATIC BOOST DC–DC CONVERTER WITH A HIGH VOLTAGE GAIN

Abstract

 This paper proposes an integrated quadratic-boost converter and a passive clamping circuit with a high voltage gain and reduced voltage stresses. The conventional quadratic boost converter has a limited voltage gain, which is not suitable for high-step-up applications with various microgrids. In the proposed converter, to improve the voltage gain beyond that of a quadratic converter, a coupled inductor is adopted.  Additionally, improved fixed current-mode (CM) control for the quadratic boost converter in the presence of uncertain load resistance is adopted. Specifically, the existing CM control law is modified to include an additional proportional action and using a normalized output error in order to achieve improved performance. The extra proportional action helps to improve the relative stability. An approximate stability analysis was carried out to gain some useful insight into the proposed CM controlled system. Moreover, the reverse-recovery problem of the output diode can be alleviated by the leakage inductance. Therefore, the total power efficiency is improved. The theoretical analysis of the proposed converter is verified with a 300-V, 120-W prototype.