The main source of shortening the lifetime of the drive is the smoothing capacitor. The characteristics curve of a single white LED. Showing of 13 references. If the OFF period is long enough, the value of the diffusion capacitor will be very small, causing a dramatic drop in the output voltage that might cause flicker in the LED light. Guedes , Henrique A. Martin , Alex J.
|Date Added:||23 July 2012|
|File Size:||20.11 Mb|
|Operating Systems:||Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X|
|Price:||Free* [*Free Regsitration Required]|
Modified harmonic injection technique for electrolytic capacitor-less LED driver – Semantic Scholar
Also, the switching frequency of the buck converter is selected such that minimum ripple appears at the output. The design is based on the utilization of the internal capacitance of the LED to replace the smoothing capacitor. Several works on electrolytic capacitor-less LED drives have been presented to maximize the overall lifetime of the LED system and the recent states of the art are given in capacitorlees 1 — 7 ]. This indicates that as the DC current increases, the value of the resistance will decrease.
US9648684B1 – Capacitor-less LED drive – Google Patents
The LED equivalent circuits shown in Figure 3 are used in this analysis. Cqpacitorless ripple voltage decreased with the increase in frequency. Consequently, this will limit the OFF period, therefore limiting the frequency and duty cycle to certain ranges.
The effective capacitance of the LED is found as follows:. This indicates that as the DC current increases, the value of the resistance r d will decrease. The present invention relates to power supply circuits, and particularly caacitorless a capacitor-less LED drive. Citations Publications citing this paper.
Mathematical analysis and experimental results are given in Section 3. GuedesHenrique A. BragaMarco A. Such a configuration can be utilized to enlarge the total internal capacitance, and hence minimize the output ripple.
The result is shown in Figure Several works on electrolytic capacitor-less LED drives have been presented to maximize the overall lifetime of the LED fapacitorless.
USB1 – Capacitor-less LED drive – Google Patents
This fact is supported by experimental results. It is clear form Figure 4 that as the current increases, the value of will decrease.
Section 2 describes the proposed design. Syms, Electrical Properties of Materials9th edition, Subscribe to Table of Contents Alerts. Table of Contents Alerts. In the AC model of Figure 3the behavior of and gives an indication that as the DC current increases, the ripple voltage will decrease, which is another parameter that can be controlled and affect the ripple voltage.
The efficiency can be improved further using an inductor with smaller internal resistance and transistor with smaller ON resistance. High power factor, electrolytic capacitor-less driver circuit for light-emitting diode lamps.
However, increasing the switching frequency will reduce the efficiency of the drive because of the switching power loss for light loads. Dragan, Fundamentals of Power Electronicsvol. The approximate voltage ripples assuming linear models and a small ripple voltage are given by [ 10 ] where is the switch frequency ofis the inductor, is the voltage across the inductor resistance, and ESR is the capacitor series resistor.
The efficiency was found by measuring the DC output voltage, the output current, the DC input voltage and the input current for each duty cycle for different frequencies.
Efficiency is an important factor in an LED drive. Topics Discussed in This Paper.
Such configuration can be utilized to enlarge the total internal capacitance and hence minimize the output ripple. These topologies lead to larger area and higher cost. It is clear from plot that as the current increases, the value of RLED will decrease.