Abstract
The strict restrictions imposed both by mandatory regulations and by the recommendations contained in current standards have led to the fact that most commercially available LED ballasts nowadays use two-stage topologies. The first stage is intended to comply with the harmonics standards and the second stage is used to control the LED current and reduce the low frequency ripple. In this work, a new DC–DC resonant converter topology is presented. This topology is derived from a modified Class-E resonant inverter by adding a clamping diode. This diode achieves a double goal: it limits the maximum switch voltage and works as a power recirculating path. This way, the proposed topology behaves as a loss-less impedance placed in series with the LED thus allowing to control the output power. This converter maintains the extremely small switching losses inherent to the Class-E inverter while reducing the voltage stress across the switch. This work presents a simplified design methodology based on the fundamental approach. This methodology was used to design and build a DC–DC post-regulator for a 40 W LED lamp. The results obtained with the laboratory prototype show that this circuit can be used to stabilize and dim the LED current while maintaining very small losses. The measured efficiency was 95.7% at nominal power and above 90% when dimmed down to 25%.
Highlights
Since the appearance of the first high-efficiency blue LEDs in 1993, solid-state lighting devices have experienced a strong advance
power factor (PFC) is made using plastic film instead of electrolytic case, the second to handle a greater input voltage ripple order to reduce the size of the capacitors
Techniques used in the bibliography to derive resonant converters standardfrom configurations of the techniques used in the bibliography to derive resonantfrom converters standard is based on adding resonant networks
Summary
Since the appearance of the first high-efficiency blue LEDs in 1993, solid-state lighting devices have experienced a strong advance. There can be found currently in the market chip-on-board (COB) LED modules of more than 200 W Another important feature of LEDs is their fast response and ease of control, enabling the implementation of complex control strategies [4,5,6]. Second stage is used the LED current and minimize the light flicker. LED strings, adding dimming capability, flicker reduction, current balancing across multiple adding dimming capability, or or implementing light modulation techniques for visible light communications [13]. PFC is made using plastic film instead of electrolytic case, the second to handle a greater input voltage ripple order to reduce the size of the capacitors. In thisstage case, has the second stage has to handle a greater inputinvoltage ripple in order to reduce required capacitor.
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