A Generalized Relationship for Calculation of Critical Inductance in an n-Input Buck DC-DC Converter

critical inductance is one of the factors that decides continuous, boundary or discontinuous conduction mode of dc-dc converters. In applications like mining, the Continuous Conduction Mode (CCM) and consequently safety of converter can be guaranteed by proper selection of inductance. So, calculation of critical inductance and proper sizing of inductor is an important issue in designing of dc-dc converters. In this paper, a non-isolated n-input buck dc-dc converter is introduced. Then, the operational modes and energy transfer process is investigated and discussed in detail. The critical inductance is calculated for 3 and 4-input versions. Using the inductive reasoning, a generalized relationship is proposed for calculation of critical inductance of converter with any number of inputs (n-input version). The proposed generalized relationship not only reduces the amount and time of calculation in design stage, but also presents a better view of performance of converter. The 3 and 5-input version of converter has been modeled and simulated in PSCAD/EMTDC software. Also, the 3-input version of converter has been practically implemented. The obtained simulation and experimental results confirm the validity of proposed generalized relationship for critical inductance calculation of n-input buck dc-dc converter.