Comparison of digital LQR techniques for DC-DC boost converters with large load range

Abstract

This work presents a comparison of three state feedback controllers suitable for application to DC-DC boost converters with large load range. These converters are an important stage in several renewable source systems. The first controller is a conventional LQR designed for a single operating point. The second controller uses the switching between LQR controllers designed for a set of load conditions (local controllers). The third controller is a fuzzy logic based controller which is based on the convex combination of the local controllers. The second and the third controllers use the load current as a decision variable. The implementation of all controllers is carried out in a TMS320F2812 fixed-point DSP, considering the transport delay and the limitation of data format from this digital control platform. Simulation and experimental results obtained for the three control strategies submitted to load disturbances allow to observe the quality of the transient and steady state responses, leading to the conclusion of the superiority of the fuzzy logic based controller in terms of a better tradeoff between performance and spent of control energy.