Output Ripple Voltage Analysis of Quadratic Buck–Boost Converters with Switched Inductor Network in the Entire Dynamic Range

Abstract

In order to provide theoretical guidance for the design of quadratic Buck–Boost converter with switched inductor network, the minimum current flowing through the energy storage inductor L3 is compared with the output current and zero, the working mode of the converter can be divided into the complete inductor supply in continuous conduction mode(CISM-CCM), the incomplete inductor supply in continuous conduction mode(IISM-CCM)and the incomplete inductor supply in discontinuous conduction mode(IISM-DCM). Within the given input voltage and load range, the working region of the converter is divided into five parts according to the different value of the inductor L3. By analyzing the output ripple voltage of the converter in the five working areas, and the maximum output ripple voltage of the converter is obtained. Based on the relationship between the maximum output ripple voltage of the entire dynamic range and the value of the inductor L3, it is pointed out that the output voltage ripple of the converter in CISM-CCM is the smallest and independent of the inductor L3, and that the output voltage ripple in IISM-CCM and IISM-DCM is much larger and increasing with the decreasing of the inductor L3. Meanwhile, it is concluded that the minimum inductance to guarantee the lowest output ripple voltage is the critical inductance between CISM-CCM and IISM-CCM. Finally, the experimental results verify the rationality and correctness of the theoretical analysis.