Evaluation of Current Control Structures for Multi-Phase Interleaved DC-DC Converters

Abstract

Several current control concepts for non-isolated interleaved DC-DC converters are systematically evaluated in terms of their dynamic and steady state performance, based on defined performance evaluation indicators. Various current control structures suitable for multi-phase interleaved systems are studied: i) a conventional PI controller with a single update per switching period, ii) a PI controller with a fast execution rate, equal to the sampling frequency instead of the switching frequency iii) a LQR-based state feedback controller (SFC), iv) a model predictive controller (MPC), and v) an adaptive hybrid controller that consists of a hysteretic controller during transient and a PI controller during steady state. Each of these control structures is optimized based on the same multi-objective optimization routine and a defined cost function. After the optimal controller design for each control structure is identified, the optimized designs are compared to identify the advantages and disadvantages of each structure. Additionally, a high current prototype current source based on a multi-phase interleaved converter with 6 interleaved modules switching at 60kHz is used to verify the most promising control structures, the developed models, and the results presented in this paper. Among the different studied structures, the adaptive hybrid controller is shown to exhibit the best performance to step transients and the MPC shows great potential following arbitrary waveforms, but also striking shortcomings in the presence of measurement noise.