Monthly Archives: March 2016

  • 12
    May 09

A Family of High Efficiency Variable Frequency Soft-Switching Off-line DC-DC Converters

The paper presents a family of off-line DC-DC converters for medium to high power delivering more than 95% efficiency for output levels of 12 to 48 V. The multi-layer PCB solution allows for low profile converters with multiple applications, from AC-DC adapters to TELECOM and computing. The main gain of this new design approach consist in using variable frequency topology with high frequency zero voltage switching (ZVS) and zero current switching (ZCS) for primary switchers. Theoretical considerations and practical results are presented for high frequency and high voltage soft-switching. The goal of the designs is to maintain a reasonable temperature rise of the multi-layer PCB board while delivering up to 90 W and respective 750 W power in a reduced volume and low cost.

  • 15
    Feb 09

750W High Efficiency and Soft-Switching Off-Line 12 V Converter

The paper presents an innovative off-line low profile converter design that delivers 750 W of power at 95%-96% efficiency for nominal input range, using variable frequency topology with high frequency zero voltage switching (ZVS) and zero current switching (ZCS) for primary switchers. Theoretical considerations and practical results are presented for high frequency and high voltage soft-switching. The goal of the design is to maintain a reasonable temperature rise of the multi-layer PCB board while delivering 750 W power in a reduced volume and low cost. The resulting product increases more than twice the power density compared to the standard two stages 400V to 12V power converters and outperforms other one stage solutions in a 125 x 70 mm2 footprint with only a 18 mm profile.

  • 27
    May 08

High Efficiency Adapter Using Dual Switch PFC-Flyback Single Stage

The paper presents an innovative design that delivers 85W of power at more than 91% efficiency in a low profile using a high frequency quasi-resonant fly-back topology with synchronous rectification, and improved power factor based on dual switch method. A closed to 0.9 power factor is achieved employing only one magnetic element and two primary side switchers. A significant power density increase is obtained due to a combination of smaller bulk capacitor and a smaller magnetic element.

  • 23
    Feb 08

High Efficiency 100W Quasi-Resonant Multi-Phases Interleaved PFC Using Planar Magnetic Components

The paper presents an innovative PFC design that delivers 100 W of power at 96%-97% efficiency for nominal input range, in low profile using a high frequency quasi-resonant interleaved boost topology, while maintaining a reasonable low cost of the ac-dc adapter. Theoretical considerations and practical results for high frequency interleaved boost converters are described. The goal of the design is maintaining a reasonable temperature rise of the case while delivering 100W power in a reduced volume. The resulting product increases more than twice the power density compared to the standard notebook universal adapters.

  • 21
    Mar 07

ZVS and ZCS High Efficiency Low Profile Adapter

The paper presents an innovative design that delivers 65W of power at more than 91% efficiency in a footprint of a business card using a high frequency quasi-resonant fly-back topology with synchronous rectification, while maintaining a reasonable low cost of the AC/DC adapter. Topology and techniques for obtaining ZVS and ZCS for high frequency and high voltage switching are described. The goal of the design is maintaining a reasonable temperature rise of the case while delivering 65W power in a reduced volume. The resulting product increases more than twice the power density compared to the standard notebook adapters.

  • 10
    Jan 06

Increasing The Efficiency In High Current And Low Voltage Application

The paper will present a converter design targeted to push the performance in respect of efficiency and power density while reducing the cost. The innovation will come from the topology, magnetic structure, drive circuit and the control method. It will present a group of innovation which together lead to a design with outstanding performance.These technologies will be implemented in a 12V output voltage bus converter for HP , delivering 450W with limited airflow.

  • 15
    Sep 05

Magnetic Integration For High Density And High Efficiency Applications

The tutorial will present a comprehensive overview of the integrated and quasi-integrated magnetic concepts and implementations. In the quest for higher power densities and higher efficiency integrated magnetic structures have become more popular. There will be presented many forms of integrated magnetic in close correlation with converter topologies. Included are several structures wherein the transformer and the storage elements are placed on the same magnetic core, forming the traditional integrated magnetic with emphasis on the latest trends. In addition to this will be presented structures wherein two independent power trains are placed on the same standard magnetic core and structures wherein the main transformer and a signal transformer are sharing the same magnetic core without interference. The focus for the integrated magnetic will be for low profile and or planar magnetic structures. Ripple steering in new applications will also be presented. There will be presented the advantages of different forms of magnetic integration in very high current and low voltage application. The seminar will also show present and future trends in magnetic integration and new forms of planar magnetic.

  • 18
    Jan 05

Increasing The Efficiency In High Current And Low Voltage Application

The continuous quest for lower voltage and higher current has created some challenges for the power designers especially if the high efficiency and high power density is pursued. This paper will underline the challenges associated with very low voltage and high current application. It will focus mostly on the reduction of effective duty cycle due to the leakage and stray inductance. It will present a magnetic structure which actually minimizes not only the leakage inductance but also the stray inductance which plays a crucial role in this application. In addition to that the magnetic structure reduces by a factor of two the footprint of the magnetic core, using a special layout structure which leads to cancellation of the magnetic filed created by the flowing current outside of the transformer the stray inductance is practically eliminated. These concepts were implemented in a 1.2V @100A quarter brick isolated DC-DC Converter which has an efficiency 2% higher than the competition at full load and reached 90% for 1.2V @ 60A, higher than many VRMs.

  • 18
    Jan 05

Magnetic Integration Through Multiple Functions In The Magnetic Cores

The paper presents a method of employing a magnetic core for multiple functions. For some magnetic cores shapes such EE and EI, we can implement two independent functions. These functions can be two independent power processing, can be a signal processing and power processing, or can be a power transfer and energy storage. In the continuous quest for miniaturization and cost reduction, these technologies offer a significant advantage. Several example of such implementation in high density DC-DC Converters will be presented.

  • 20
    May 03

Constant Voltage Reset Circuit

This paper presents a reset mechanism, which combines the advantages of the active clamp reset and the traditional third wire reset technique. In this concept the reset voltage is constant similar to the third wire reset, wherein a constant voltage is applied to the transformer during the reset cycle. The technology has several key advantages from the active clamp reset mechanism. The energy contained in the leakage and magnetizing inductance is recycled, and the voltage across the main switch is clamped. In addition to this, the flux through the transformer is symmetrical to zero and the duty cycle can be higher than 50%, similar to the active clamp circuit. Though this circuit contains most of the active clamp circuit’s key features it does not exhibit its limitations. One of the drawbacks of the active clamp circuit is its behavior during transients wherein the duty cycle changes. During transients, until the reset capacitor charges to its optimum level, the voltage across the switch may reach uncontrollable levels. In this reset technique the voltage across the switch is constant regardless of the duty cycle and reacts to transients without any limitations. In addition to this the implementation is very simple; it does not require any additional driving and timing circuits for the reset switch. The reset switch is driven directly form the transformer by a driving winding and the reset voltage can be easily adjusted by a resistor divider. Using this technology a DC-DC converter was implemented, providing 1.2 V @ 20A, from an input voltage range of 36 V to 60 reaching an efficiency of 86% at full load. Another application of this technology in a 1/8 brick DC-DC Converter is also presented.

Older Posts

Search

Recent Posts

Archives

This website is solely maintained by Rompower Inc.The over-all content (content being images, text, sound and video files, programs and scripts) of this website is copyright © 2018 Rompower Inc. All rights reserved