Modeling and Analysis of Coupling Effect in Four Legged Core for Multi-phase Buck Converter

As a popular topology in point of load (PoL) application, multiphase buck converter always faces a tradeoff problem between faster load-transient response and smaller inductor ripple current, which is solved by the coupled inductor in a number of literatures. This paper is aimed at modeling and analysis for a four-legged integrated indirect coupled inductor applied in a four-phase buck converter for 5 V DC to PoL application. The quantitative analysis is conducted through an equivalent steady-state inductance model. Inductor operation is investigated under different duty cycle in the circuit simulation using parameters extracted from FEM simulation. The result is then verified using a highly compact converter prototype. Finally, efficiency performance of the prototype is tested for seeing the integrated inductor practical value in industry.