Dalla Costa , Tiago B. The internal capacitance of the LED or an LED array will act as smoothing capacitor when a proper switching frequency and duty cycle are chosen. A new approach to designing capacitor-less buck DC-DC converter was developed and tested. US USB1 en The minimum ratio of ripple voltage to DC voltage is around 1. Most of the works presented require relatively complicated power circuits or current controlled technique to reduce the size of the energy storage capacitor.
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The ripple voltage decreased with the increase in frequency. 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. However, increasing the switching frequency will reduce the efficiency of the drive because of the switching power loss for light loads. Section 2 describes the proposed design. The inductor and the smoothing capacitor will average the pulses passing through causing ripples on the load.
Experimental results are displayed in plot of FIG. GuedesHenrique A. However, most of the works presented require relatively complicated power circuit or current-controlled technique to reduce the size of the energy storage capacitor.
A New Capacitor-Less Buck DC-DC Converter for LED Applications
As for LED lighting applications, the LED load needs to draw high current specially when using a capacitor-less drive. As shown in FIG.
Rewriting 6 to find the effective capacitancePlots of the effective capacitance as ldd function of the LED current for different frequencies are shown in Figure 5. However, increasing the switching frequency will reduce the efficiency of the drive because of the switching power loss for light loads [ 12 ].
Active and Passive Electronic Components
Citations Publications citing this paper. These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. LED lighting is replacing the florescent lighting because of its advantages, mainly low power consumption and long life expectancy.
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.
Modified harmonic injection technique for electrolytic capacitor-less LED driver – Semantic Scholar
However, during the OFF period in the switching Buck converter pulse, the LED internal resistance will draw the stored charge, and the output voltage will decrease. The components used are as follows: Combining 4 and 5the output voltage ripple is given by where. Active and Passive Electronic Components. Description of the Related Art Light emitting diodes LEDs are beginning to experience widespread use in many lighting applications.
Such a configuration can be utilized to enlarge the total internal capacitance, and hence minimize the output ripple. A gate of the transistor Q 1 is connected to a pulse capacitorleas, Vpulse, which switches the transistor Q 1 on and off at a selected duty cycle. The minimum ratio of ripple voltage to DC voltage is around 1.
Modified harmonic injection technique for electrolytic capacitor-less LED driver
Ahmed and El-Sayed A. Wu Chen and Hui, S. Subscribe to Table of Contents Alerts.
The DC output voltage is given by:. Switch control device, power supply device comprising the same, and driving capacitorlrss of power supply device. This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
In [ 2 — 7 ] several single-stage topologies using multiple switches or using shared switch techniques are presented.
This case will satisfy the ideal situation with a negligible load effect on the ripple voltage. Backlight unit, display apparatus including the backlight unit and operating method thereof. The effective capacitance of the LED is found as follows: A capacitor-less LED capaciyorless, consisting of: Pulse signal processing Mathematical optimization Simulation.