Search

This paper presents an electric equivalent model of the Induction Electrodeless Fluorescent Lamps (IEFL). The model is based on resistances and reactances and takes into account the real and reactive lamp power. One of the most important features of the proposed methodology is the concern regarding core losses and lamp reactive characteristics. In order to obtain and validate the IEFL model, a series-parallel resonant half-bridge inverter is used as the ballast power stage. Lamp discharge and coils are modeled as resistances and reactances depending on the lamp power. Simulations employing the proposed model are presented in this paper and they are in agreement with experimental results. [ABSTRACT FROM PUBLISHER]

This paper presents a self-oscillating electronic ballast to operate T5 HO fluorescent lamps with power ratings of 24 W, 39 W and 49 W. The proposed circuit detects the lamp type by measuring the lamp voltage through a control circuit which changes the power factor correction circuit duty cycle to adequate the output power. Experimental results are shown to demonstrate the feasibility of the proposed solution. [ABSTRACT FROM PUBLISHER]

This paper deals with the thermal characteristics of the I-V curve of GaN-based white LEDs, focused on the variations of the dynamic resistance. The final goal of this study is to improve the static and dynamic operation of the LED driver within a wide range of temperature. Four LEDs from different manufacturers were chosen for this study. The first part of the paper shows the thermal characterization of the forward voltage at a given injected current. After that, the experimental data are fitted in order to calculate the junction temperature accurately. Then, a small-signal analysis where the LEDs are supplied with dc current and an ac perturbation superimposed at the operation point under variable junction temperature is covered. This analysis allows the dynamic resistance to be experimentally determined for a wide junction temperature range. Furthermore, the experimental data have been fitted in order to establish the relationship between junction temperature and dynamic resistance variation, so the dynamic resistance can be determined for a given operation point. Finally, an illustrative example is presented as a case study in order to analyze the implications of the dynamic resistance on the output current ripple and on the closed-loop operation of an LED driver. The experimental results confirm that the junction temperature shift induces a variation in the dynamic resistance, which might have a significant effect on the output current ripple and closed-loop performance in certain LED fixtures. [ABSTRACT FROM PUBLISHER]

This paper presents an electronic ballast to operate HO fluorescent lamps with power ratings of 24 W, 39 W and 49 W. The proposed circuit detects the lamp type by its operation voltage and sets duty cycle of the power factor correction circuit to adequate the output power. Experimental results are shown to demonstrate the feasibility of the proposed solution. [ABSTRACT FROM PUBLISHER]