Search

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.

In recent years, induction heating applications assisted by electronic power control have been very appealing. For melting applications, induction heating is widely used as it seems to be appropriate and provides higher efficiency, zero pollutants, non-contamination of material, etc. in comparison with conventional heating. The conventional variable frequency control scheme is not sufficient for melting applications because of its high switching loss, low efficiency, and lower heat rate. A superlative control technique is required to control the output power smoothly, for a high heating rate with minimum power loss, and to lower the number of components. In this paper, a capacitorless self-resonating bifilar coil is proposed for induction surface melting applications. The performance of the system in terms of modular losses, heat rate, and efficiency is analyzed for various power methods such as pulse duty cycle control, phase shift control, pulse density modulation control, and asymmetric duty cycle control. An experimental validation is performed for the 1 kW prototype, and the heating rate, efficiency, and modular losses are calculated. The control technique is digitally validated using a PIC16F877A microcontroller with 30 kHz switching frequency. The temperature distribution is analyzed using a FLIR thermal imager. Among the tested methods, pulse density modulation-based control provides smooth and varied power control from 0% to 100% with minimum modular losses. The efficiency of the system is 89% at a rated output power and is greater than 85% for pulse density modulation control with a fast heating rate.