Design of Robust Guaranteed Margin Stability Region PI Controller for Automotive LED Lighting With Parameter Uncertainty

Abstract

In the modern era, automotive light emitting diode (LED) lighting technologies are booming as a result of high luminous intensity, long life, compact size, high energy efficiency, high reliability etc. As the load is sensitive for input parametric variations, it is essential to regulate the load voltage and current with respect to system specifications. Hence, there is a need for fast response robust controller to feed the required voltage and current during abnormal conditions. In this paper, a robust controller is designed for single switch control buck boost converter for automotive LED lighting. A small signal modelling of the converter is developed with perturbed state variables to analyze the dynamic behavior of the system. The system with dynamic controller has a zero in the right-hand side of the s-plane, which results in poor closed loop stability. Hence, a robust controller is designed with Kharitonov’s theorem by considering the uncertain variations in the converter parameters. A robust performance region is obtained by considering guaranteed gain margin and phase margin benchmark. In this region, the optimal PI controller gain values are obtained using Kharitonov’s sixteen plants theorem. The obtained gain values make the system with minimum oscillation, fast settling time, right hand side zero compensation and stability of the system. The performance analysis is compared with the conventional PI controller and to ensure the peak value of sensitivity for robust controller. The simulation of the system is performed in PSIM and validated in real time using dSPACE1103 controller with experimental results.

Keywords

• DC-DC power converter
• Kharitonov’s theorem
• LED lamps
• robust control
• stability
• uncertain systems