Combination of Buck and Boost Modes to Minimize Transients in the Output of a Positive Buck-Boost Converter

This paper describes a new method for minimizing the transients in the output of a DC-DC converter required for small powered portable electronic applications. The transient problem has been the most serious problem for power supplies needing the output voltage in the mid-range of the input voltage. The maximum transient arises when the input voltage becomes almost equal to the output voltage. Selecting the best approach involves a tradeoff among cost, efficiency, and output noise or ripple. There are various techniques used to solve the problem of transients. However, most of the methods have drawbacks such as comparatively higher transients or lower efficiency because of the longer switching operations. This paper describes few methods already been used to solve the transient problem and points out the demerits of those methods. In addition, a new combination method, which combines buck and boost modes during the transition mode, is described in this paper to minimize the transients at the output of the converters when the input voltage is near to the output voltage. Mathematical equations have been put forward to support the proposed idea for the transient minimization. Simulation results have been added to make a comparative analysis of transient response of this method with respect to the other methods