Status : Verified
| Personal Name | Escultero, Arvin D. |
|---|---|
| Resource Title | Two-stage LED driver based on buck and LCC resonant converter operating at the constant current frequency |
| Date Issued | 15 June 2020 |
| Abstract | LEDs are widely used in smart farms because of high efficacy, ease of control and consistent wavelength. In this application, a driver capable of delivering high power constant current with dimming capability is required. To utilize the benefits of LEDs in smart farms, an appropriate driver based on buck and LCC resonant converter was designed, simulated, and tested. Resonant converters are growing in popularity in these applications due to their soft switching capability which allows higher frequency of operation without compromising efficiency. When operating at a certain frequency, the LCC functions as a constant current source, but locating the exact frequency of operation to exploit this feature poses a challenge due to component value tolerances. Since resonant converters usually operate at frequencies 100kHz or higher, changes caused by tolerance in the values of the reactive components cause a significant shift from the desired operating frequency. A conventional solution is by using high precision components, but these are more expensive. This driver was designed with a unique feature to track the LCC constant current frequency despite tolerances in the component values. This was done by utilizing resonant frequency tracking techniques and carefully designing the LCC quality factor. This allows constant current output despite the use of low precision components and the absence of a regulating current feedback loop. Dimming capability for the LED output was also available using the buck section PWM which is easily set through the microcontroller. The design procedure was developed and verified with a 120W prototype which was tested on all operating conditions. Results show the driver was capable of delivering constant current, with a dimmable range of 200mA up to 2A, to the LED strings at high efficiency which peaked at 92.88%. The tracking algorithm was used to set the operating frequency which was detected despite the large shift of 19kHz above the nominal |
| Degree Course | MS Electrical Engineering |
| Language | English |
| Keyword | Resonant Converters; Constant Current; Tracking; LCC; LED |
| Material Type | Thesis/Dissertation |
Preliminary Pages
3.85 Mb
Category : F - Regular work, i.e., it has no patentable invention or creation, the author does not wish for personal publication, there is no confidential information.
Access Permission : Open Access