Model predictive control for pre-compensated voltage mode controlled DC-DC converters

This study introduces the use of model predictive control (MPC) to improve the performance of pre-compensated power supplies, and in particular of DC-DC converters, by dynamically modifying their output voltage reference. The importance of developing controllers for pre-compensated converters is twofold. First, the hierarchical structure is particularly useful when the primal controller is already coded, or hardware based, and cannot be changed. Second, the double-loop and, possible, multi-rate structure represents a computationally cheaper alternative to a direct MPC that would replace the primal controller and would require a much higher sampling frequency. In this study a MPC controller has been applied for the regulation of a pre-compensated synchronous DC-DC buck converter. The aim is to improve the performance of standard voltage mode control (VMC), without replacing the linear controller and without drastically affecting the computational burden. The algorithm has been tested both in simulation and experimentally, on commercially available hardware. The results show the performance improvement with respect to the standard VMC, as well as the feasibility of the proposed approach in an embedded platform. Tests with different primal controller tunings, and unknown varying loads, confirm the advantages of the method. © The Institution of Engineering and Technology 2017.