Power Electronics

Charting the Future in Switching Power Converters

Find a downloadable version of this story in pdf format at the end of the story.

I MET DR. SLOBODAN CUK many years ago at the Power Systems World conference sponsored by PCIM (Power Conversion and Intelligent Motion) magazine, now Power Electronics Technology. At the time, Dr. Cuk was Professor at the California Institute of Technology (Caltech) and in charge of its renowned Power Electronics Group. In August of 1979, Dr. Cuk also started the Optimum Power Conversion, Inc., d.b.a. TESLAco.

TESLAco had an exclusive license from Caltech to the CUKonverter. For the invention of a new switching converter topology and several of its extensions, Dr. Cuk won the IR 100 Award in 1980 from the Industrial Research Magazine. Dr. Cuk also won the Franklin Institute Edward Longstreth Medal Award in 1991 for pioneering and expediting the development of integrated magnetics and switched-mode power conversion.

TESLAco gained its reputation as a hi-tech company by specializing in custom designs of the high efficiency and high power density switch-mode power supplies for commercial, industrial, medical, military, and space applications.

Until recently, TESLAco primarily employed patented TESLAconverter technology that was invented by Dr. Cuk ten years ago and is protected worldwide by four U.S. patents and equivalent foreign patents. DC/DC designs based on the TESLAconverter technology, which are currently on the market, can exceed 96% efficiency, which allows convection cooling even if implemented in a small size chassis. This high performance technology is currently used also in power supplies for space applications.

This year I met Dr. Cuk again. He pointed out that it was previously considered impossible to have an isolated ac-dc converter with PFC in a single power processing stage and without the mandatory full-bridge rectifier. Dr. Cuk's article in the October 2010 Power Electronics Technology proved that this is not the case any more. The July article introduced the performance of a non-isolated Bridgeless PFC converter with 0.999 power factor and 1.7%THD harmonic distortion, which achieved 98% efficiency.

It is extraordinary that a new converter topology can replace 14 switches and four magnetic elements of conventional Three-Stage approach with just three switches and a single magnetic component. Based on the new Hybrid Switching and Storageless Switching Methods, invented by Dr. Cuk, the new converter topologies provide simultaneously dramatic reduction of size, weight and cost and yet still further reduce the losses. Moreover, the October article analyzed just one possible converter topology, and Dr. Cuk's article in this November issue of Power Electronics Technology introduces yet another solution, which even further reduces component count, size and cost.

The next year marks the 35 years of unveiling of State-Space Averaging method. Dr. Cuk, as the originator of the Method was invited and will present a keynote address at the 2011 APEC conference in March 2011 with his Invited Paper: State-Space Averaging: Past, Present and Future. In this paper, Dr. Cuk will demonstrate how he has extended his State-Space Averaging Method to recently introduced Hybrid Switching method.

As shown in Power Electronics Technology articles, the hybrid switching method enables a direct AC-DC conversion with PFC and isolation in a single-stage and yet retains simple duty ratio control despite multiple resonances. Using capacitive energy transfer, it eliminates the large number of switches characteristic of bridge-type converters in current square-wave PWM, resonant, and quasi-resonant converter topologies that rely on inductive energy transfer.

We are not quite sure what to expect next from Dr. Cuk, but Dr. Cuk confirms that TESLAco has licensed and is developing a number of products for its customers in US, Japan and European Union, which are expected to elevate Power Electronics Technology to the entirely new Green Dream Technology level.

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