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This paper presents a new methodology for the determination of fluorescent lamp models based on equivalent resistances. One important feature of the proposed methodology is concerned with the inclusion of the filaments into the model, considering the effects of dimming operation on the equivalent resistances. The classical Series-Resonant Parallel-Loaded Half-Bridge inverter is used as the power stage of the ballast. Moreover, the variation of the inverter's switching frequency is the dimming technique assumed for the analyses. Results obtained with a F32T8 lamp indicate that the accuracy of the model is very satisfactory. Thus, the lamp models obtained with the proposed methodology have the potential to serve as an important tool for ballast designers, considering the necessity for evaluating the lamp/ballast compatibility, according to issues concerned to the operating conditions of the electrodes' filaments.

This paper presents a new methodology for the adjustment of the preheating process and steady-state operation of electronic ballasts intended for hot-cathode fluorescent lamps. The classical series-resonant parallel-loaded half-bridge inverter is the power stage analyzed in this paper. In addition, the preheating process is based on the imposition of a constant rms current through the electrodes, in order to provide a proper value of the ratio before the lamp start. According to the proposed methodology, it is possible to set suitable operating points for the electronic ballast, considering optimal conditions for the lamps electrodes. Therefore, the proposed methodology for setting the preheating and steady-state operation is a complete platform to the design of electronic ballasts for hot-cathode fluorescent lamps.

This work presents a new family of dc to dc converters based on a new zero-current-switching (ZCS) pulse-widthmodulated (PWM) soft-commutation cell. Two transistors (main and auxiliary switches), two diodes, two small resonant inductors and one resonant capacitor compose this commutation cell, appropriated to operate with insulated-gate bipolar transistors (IGBTs) as the power switches.This new ZCS-PWM cell provides a zero-voltage (ZV) turnon to the diodes, a zero-current (ZC) turn-on and a zero-currentzero-voltage (ZCZV) turn-off to the transistors.The new family of converters, originated from the proposed ZCS-PWM cell, offers conditions to obtain isolated converters, as example: derived Buck-Boost, Sepic and Zeta converters.An application of the new commutation cell in a new ZCS-PWM Boost rectifier is developed, obtaining a structure with power factor near the unity, high efficiency at wide load range and low total harmonic distortion (THD) in the input current.The principle of operation, the theoretical analysis and the design procedure are presented. A design example is developed and experimental results to the new high-power-factor (HPF) ZCS-PWM Boost rectifier are presented to verify the theoretical analysis.

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