Guedes , Henrique A. Mathematical analysis and experimental results are given in Section 3. The minimum ratio of ripple voltage to DC voltage is around 1. This is because it is better to use many parallel LEDs for higher summation of LED capacitance, which gives this method one more advantage. The output voltage is measured across the LED packages. Moreover, the value of also is a function of the conductance and its value will increase as the current increases [ 11 ]. To find the effective capacitance of the LED, the ripple current is given by where is the ripple current through the inductor. 
| Uploader: | Fenrigul |
| Date Added: | 2 April 2014 |
| File Size: | 25.84 Mb |
| Operating Systems: | Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X |
| Downloads: | 61666 |
| Price: | Free* [*Free Regsitration Required] |
It capacitorlesa clear from plot that as the duty cycle increases, the DC output voltage increases. Moreover, the value of also is a function of the conductance and its value will increase as the current increases [ 11 ].
Modified harmonic injection technique for electrolytic capacitor-less LED driver
We assume the ac source is rectified and provides a DC output called Vin with nominal voltage of 35V. Increasing the frequency further will lead to smaller ripple voltage and smaller components for better integration.
The components used are as follows: The effective capacitance of the LED is found as follows: Caacitorless case will satisfy the ideal situation with a negligible load effect on the ripple voltage. Description of the Related Art Light emitting diodes LEDs are beginning to experience widespread use in many lighting applications.
The proposed design is based on the well-known buck converter shown in Figure 1where the output voltage is the voltage across the load resistance and. Also, the switching frequency is selected such that a minimum ripple appears at the output.
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. Plot of the effective capacitance versus the load current. 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.
High power factor, electrolytic capacitor-less driver circuit for light-emitting diode lamps. In [ 2 — 7 ] several single-stage topologies using multiple switches capacitorlesz using shared switch techniques are presented. It is important to point out that the value of C d is linearly changing with the DC current only in strong conduction mode.
An experimental study on the photometrical impacts capacitprless several current waveforms on power white LEDs Pedro S.
By clicking accept or continuing to use the site, you agree to the terms outlined in our Privacy PolicyTerms of Serviceand Dataset License. However, capaacitorless the OFF period in the switching Capacitorlese converter pulse, the LED internal resistance will draw the stored charge, and the output voltage will decrease. The main source of shortening the lifetime of the drive is the smoothing capacitor. The DC output voltage is given by: An LED or an array of LEDs capscitorless in parallel to each other is connected between the cathode of diode D 1 and a second lead of inductor L the anode of the Ledd being connected to cathode of diode D 1and hence the positive terminal of the rectifier circuitand the cathode of LED being connected to the second lead of the inductor L.
These advantages are mainly lower power consumption and longer life expectancy. MartinAlex J. The output DC and ripple voltage versus frequency. It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.
Equations 3 and 4 can be written as: These and other features of the present invention will become readily apparent upon further review of the following specification and drawings.
A New Capacitor-Less Buck DC-DC Converter for LED Applications
A gate of the transistor Q 1 is connected to a pulse source, Vpulse, which switches the transistor Q 1 on and off at a selected duty cycle. Table of Contents Alerts. Rewriting 6 to find the effective capacitancePlots of the effective capacitance as a function of the LED current for different frequencies are shown in Figure 5. As is clear from the figure, as the duty cycle increases, the DC output voltage increases.
The value of depends on the current passing through the LED, and it can be deduced from the characteristics curve of the LED shown in Figure 4. Switching power supply for an illumination device with precision current control.
Mathematical analysis and experimental results are given in Section 3. In [ 1 ], a current injection approach is used.
Super Programs Reservoir 