Temperature Rise Effects on Dynamic Resistances for Laser Diodes with a Wavelength of 450 nm for Vehicle Headlight Applications

In this paper, a laser headlight power converter (LHPC) was developed to drive the InGaN-based blue beam laser diode (BBLD). The LHPC was composed of the four-switch step-up step-down converter (FSSUSDC), the FSSUSDC controller, and the current error compensator (CEC). When the BBLD dynamic resistance was increased under the high ambient air temperature, the FSSUSDC operated in the step-down mode, and the CEC employed the proportional-integral control, the BBLD driving current exhibited an ignition current spike, which could destroy the semiconductor material of the BBLD, resulting in optical output power decay. Therefore, a new four-gradation gain (FGG) control method was proposed to mitigate the ignition current spike of the BBLD. This paper presented the BBLD temperature characteristic, an analysis of the LHPC ignition current, a CEC compensation design, and an analysis and design of the FGG control.