Thursday, September 6th, 2012

Frequency Domain Analysis of Switching Power Converters

Dr. Grahame Holmes, RMIT University, Australia

The concept of frequency domain analysis using Fourier decomposition is central to an understanding of the modulation processes for a switched power converter. The origins of these concepts derive from Bennett in the 1930’s and Black in the early 1950’s, with their application to switched power converters emerging during the 1970’s. Double Fourier series analysis is now generally accepted as the most powerful strategy available to understand the modulation processes of both two level and multilevel switched conversion systems. More recently, it has also been shown how a frequency domain representation of phase leg switching functions can be used in a substantially wider context than just converter modulation analysis.

This presentation will illustrate how the fundamental principles of Double Fourier frequency decomposition can be used to exactly analyse the operation of switched conversion systems under a wide variety of operating conditions and applications. A number of examples will be presented to demonstrate the power and capability of the approach, including Pulse Width Modulation using sub-integer carrier-fundamental pulse ratios, optimised harmonic cancellation for a variety of multilevel converter topologies, intermediate DC Link voltage balancing for multilevel converters, and an elegant way to analyse the transient response of a bi-directional DC-DC converter. The presentation will show how frequency domain analysis is a most effective way of understanding the complexity of operation of a switched power converter system.

Power Semiconductor Devices an Enabling Technology for Reliable and Efficient Power Converters -Technology Trends and Challenges

Dr. Leo Lorenz, Senior Director (retired), Infineon Technologies; Director of ECPE, Germany,

Power semiconductor devices are a driving technology for energy efficiency, E-Mobility and Renewables. The major electrical improvement of the new generation of power devices is coming from the overall silicon utilization. Based on this idea the technology Roadmap follows a chip horizontal optimization (higher cell densities) and a vertical optimization to minimize the drift layer and reduce the bulk substrate material significantly. This power device mainstream technology development is applied to all device types such as the IGBT, Fast Recovery Diode, Super Junction Transistor and low voltage MOSFET.

The reliability and ruggedness of these new power semiconductors is driven by an advanced chip interfacing and packaging technology. However it has to be considered that the application engineer is faced with new challenges of how to manage all the parasitic, thermal management and circuit set up.