The proposed design is a modified version of the design in Figure 1 and is shown in Figure 2 , where the load is an array of LEDs, as it is the case in all commercially available LED lamps. The nonlinearity is clearly shown in Figure 8 , where the OFF period was long enough to drive the LED to the weak conduction region while the ripple of Figure 9 is almost linear. The result is shown in plot of FIG. The result is shown in Figure A new design of capacitor-less driver is presented in [ 8 ]. 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. Active and Passive Electronic Components.
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The LED equivalent circuits shown in Figure 3 are used in this analysis.
The major intention of this paper is to build upon the results obtained in [ 9 ] and present the mathematical model and experimental results to confirm the functionality of the design.
The efficiency can be improved further using an calacitorless with smaller internal resistance and transistor with smaller ON resistance. This fact is supported by the experimental results we have carried out and it is explained in the next section.
These topologies lead fapacitorless larger area and higher cost. The Proposed Design 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.
Efficiency is an important factor in an LED drive. BenderHenrique A. Subscribe to Table of Contents Alerts. The effective capacitance of the LED is found as follows: The design is based on the utilization of the internal capacitance of the LED to replace the smoothing capacitor.
The ripple voltage is decreasing with ccapacitorless increase of frequency.
The output voltage is measured across the LED packages. The drain of Q 1 is connected to the anode of diode D 1 and to a first lead of inductor L, The capacitorrless of diode D 1 is connected to the positive terminal of the AC-DC rectifier circuit Field of the Invention The present invention relates to power supply circuits, and particularly to a capacitor-less LED drive.
Modified harmonic injection technique for electrolytic capacitor-less LED driver
Dragan, Fundamentals of Power Electronicscapacitorlesss. 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. The design used a storage capacitor and a two-winding dual inductor.
From circuit and modelassume no diffusion capacitance, C d. This is due to cwpacitorless leakage in this capacitor and, hence, degradation in the drive circuit with time.
We assume the ac source is rectified and provides a DC output called Vin with nominal voltage of 35V.
capacitirless Conventional LED drive has a limited lifetime due to present of bulky electrolytic output capacitor E-Cap which is essential to make the power difference balancing between the constant output power and the pulsating input power. As for LED lighting applications, the LED load needs to draw high current specially when using a capacitor-less drive.
Modified harmonic injection technique for electrolytic capacitor-less LED driver – Semantic Scholar
Capacitirless output DC and ripple voltage versus the duty cycle for different frequencies. The result is shown in plot of FIG. Pulse signal processing Mathematical optimization Simulation. The non-linearity is clearly shown in plotwhere the off period was long enough to drive the LED to the weak conduction region, while the ripple of plot is almost linear.
An LED or an array of LEDs connected 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 LED 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.
The proposed design is a modified version of the design in Figure 1 and is shown in Figure 2where the load is an array of LEDs, as it is the case in all commercially available LED lamps.
From This Paper Figures, tables, and topics from this paper. The ripple voltage will be affected by the duty cycle, the switching frequency, the inductance, the internal resistance of the smoothing capacitor ESR, and the value of the smoothing capacitor.
A New Capacitor-Less Buck DC-DC Converter for LED Applications
The DC output voltage is given by:. The main source of shortening the lifetime of the drive is the smoothing capacitor. It is well known that the LED in conduction mode can be modeled using a resistor and an ideal diode for DC mode and a capacitor and a resistor in parallel for AC mode as shown in Figures 3 a and 3 brespectively.
Dalla CostaTiago B.
Capacutorless result is shown in Figure 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.