Current control scheme for unbalanced current distribution in a four-phase converter

A multiphase DC-DC topology is mostly used for high current application in electric vehicles (EV), CPU processing circuit, communication systems and etc. Although this topology has an advantage of lower manufacturing costs and smaller in size. This topology, however, is susceptive to the unbalanced phase current issue which can cause malfunction to the converter. Due to this, a dual-loop control is usually used in a DC-DC multiphase converter. The outer-loop is responsible for the output reference and inner-loop handles the current balancing between each phase inductors. Conventional linear control schemes can only function within certain bandwidth and are easily affected by disturbances. This paper proposes a combination of current control scheme where the outer loop is controlled by linear controller and model predictive control (MPC) controlling the inner current loop to overcome those drawbacks. The objective of the experiment is to ensure equal current distribution between each phase when subjected to disturbances in the input source and step load changes. For comparison purposes, a pure linear compensator and the proposed method will be used in the closed-loop system. The controllers are designed using MATLAB/Simulink.