Identification and Robust Control of the Nonlinear Photoelectrothermal Dynamics of LED Systems

Abstract

In lighting systems consisting light emitting diodes (LEDs), excessive temperature is a main cause of degraded luminous efficacy, which leads to reduced average illuminance and distorted illumination rendering. Modeling the thermal dynamics of LEDs is hence essential in designing thermal dissipators and controllers for maintaining constant illuminance or chromaticity. In the existing literature, both physical modeling and system identification have been proposed, which all find the dependence of the temperature on the input power. When the power fluctuates, e.g. due to dimming control, the thermal dynamics becomes nonlinear. Moreover, when a photoelectrothermal (PET) model is used in control synthesis, the nonlinearity due to the product of the temperature dependent efficacy and the input power must be considered. These nonlinearities are either ignored or linearized in most existing methods. The main contribution of this work is treating the aforementioned nonlinearities in a linear parameter varying (LPV) framework. First, the nonlinear thermal dynamics is identified by LPV system identification techniques. Then, a controller to track reference illuminance is designed by H∞ control techniques to be robust to both the temperature and the disturbance from ambient light. The identification data and the designed controller are collected from and verified on real experimental setup.

Design of LCC HVDC wide‐area emergency power support control based on adaptive dynamic surface control

“…The developments of wide-area measurement systems (WAMSs) [7,8] and robust non-linear schemes [9][10][11][12] have brought new opportunities to design the LCC HVDC emergency power control. A non-linear robust control law, such as feedback linearisation method, sliding mode control and backstepping control technique, has been used to design the LCC HVDC emergency power control strategy based on the global signals of the AC-DC parallel system measured by WAMS.…”

Data Driven Modeling of the Reactive Oxygen Species Stimulated by Photon Energy in Light Therapies

“…The LED light sources were designed following the procedures in [20], and were driven by a constant current source with PWM current level control to stabilize the output irradiance [21], [22]. The LED chips are arranged in either a 1.5cm-by-1.5cm square as a 4-by-4 array (385nm, 405nm and 415nm) or a 1cm-by-1cm square as a 3-by-3 array (450nm).…”

Simple Form of Compact Thermal Model of the Large LED Modules

“…Many papers have been devoted to the problem of modeling thermal phenomena in power modules [30][31][32] or in LEDs and LED modules, e.g., [8,12,13,25,33,34]. The paper [13] presents a compact thermal model of power LEDs.…”