Self-Resonant Three-level Buck Converter using Auto-Compensated Zero-Current Detection for LED Drivers
Currently, power management is a knowledge present in almost all electronic devices, from PCs, smartphones to automotive and healthcare devices. More recently, LED IC Drivers have become focus of research because of the potential use of LED lighting in buildings, smartphones, healthcare appliances, automobiles, among others. Power converters of different types (switched capacitor, linear regulators, buck, boost, etc) can be used to drive string of LEDs with a specific DC current. The focus of this project is the design of a high efficient integrated LED driver.
Asynchronous power converters use the so-called freewheel diode to allow the circulation of current through the inductor; however, the use of freewheel diodes decreases the final efficiency of the converter. Synchronous converters are commonly used in monolithic approaches, in this way, switches are used to emulate the freewheel diodes. Nowadays, the trends in integrated converters can be classified in two categories: efficiency oriented and size oriented. Techniques as zero current and zero voltage switching detection are widely use to decrease the switching losses, in that way, the size of the components can be decreased using higher frequencies.
The implementation of diode emulation using zero current detection at MHz range frequencies is not trivial; challenges should be addresses in aim to obtain the best efficiency possible. Some of the challenges are:
- Zero- current detection in the inductor current without additional losses at high speed.
- Time difference between the Zero-Current instant in the inductor current and the turn-off of the switch that emulates the diode.
The final goal of this project is to design a discrete prototype using diode emulation at MHz range to be used as control unit of the zero current switched converter. The solution should improve the final efficiency of the existing converter with a low area cost and using an IC oriented design.
This master’s proposal is divided in four main stages:
- Familiarization with literature: Power converters, Zero current/voltage switching mode, Zero-current detection, diode emulation.
- Simulation and measurement of the existing IC: Three level Buck converter, zero current detection modules and diode emulation modules.
- Design, implementation of the close-loop control module using discrete components and measurements.
- Design and Layout to be incorporated in an IC.
It is desirable to have a background in analog design and Power Electronics.
This project might be supported by Philips.
Supervisor: Juan Camilo Castellanos
Project duration: 9 months