Syms, Electrical Properties of Materials , 9th edition, This is due to leakage in this capacitor, and hence this causes degradation in the driver performance with time. The result is shown in Figure As for LED lighting applications, the LED load needs to draw high current specially when using a capacitor-less drive. The negative terminal of the rectifier circuit is connected to the source of a switching transistor Q 1 in parallel with a diode, as shown at Similar reference characters denote corresponding features consistently throughout the attached drawings.
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It is evident from the plot that the effective capacitance at kHz is high, since the impedance of the capacitance is much smaller than that of the dynamic resistance.
USB1 – Capacitor-less LED drive – Google Patents
The negative terminal of the rectifier circuit is connected to the source of a switching transistor Capacitotless 1 in parallel with a diode, as shown at The result is shown in plot of FIG. The rest of the paper is organized as follows: Syms, Electrical Properties of Materials9th edition, 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.
In conduction mode, is the reciprocal of the conductance which is equal to the DC current divided by the thermal voltage. High power factor, electrolytic capacitor-less driver circuit for light-emitting diode lamps.
This indicates that as the DC current increases, the value of the resistance will decrease. It is clear from plot that as the duty cycle increases, the DC output voltage increases. Thus, a capacitor-less LED drive solving the aforementioned problems is desired.
As for LED lighting applications, the LED load needs to draw high current specially when using a capacitor-less drive. It is clear form Figure 4 that as the current increases, the value of will decrease. It is clear that the ripple is linear for higher duty cycle.
Active and Passive Electronic Components
The output DC and ripple voltage versus frequency. The design used a storage capacitor and a two-winding dual inductor.
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.
Showing of 13 references. Active and Passive Electronic Components. The effective capacitance of the LED is found as capacitorpess. Experimental results are displayed capacitorlesss plot of FIG. The capacitor-less LED drive circuit is based on a buck converter circuit where an LED replaces the smoothing capacitor.
US9648684B1 – Capacitor-less LED drive – Google Patents
Efficiency is an important factor in a LED driver. An experimental study on the photometrical impacts of several current waveforms on power white LEDs Pedro S. Subscribe to Table of Contents Alerts.
Indexed in Web of Science. Also, the switching frequency is selected such that a minimum ripple appears at the output.
Modified harmonic injection technique for electrolytic capacitor-less LED driver – Semantic Scholar
Light emitting diodes LEDs are starting to experience widespread usage in many lighting applications. The LED equivalent circuits shown in Figure 3 are used in this analysis. Dalla CostaTiago B. If the OFF period is long enough, the value of the diffusion capacitor will be very small causing a sharp drop in the output voltage that might cause flicker in the LED light.
These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. This fact is supported by experimental results. A capacitor-less LED drive, consisting of: The efficiency can be improved further using an inductor with smaller internal resistance and transistor with smaller ON resistance.