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Keynote

Single-Stage AC-DC Converter Topologies of 98% Efficient Single-phase andThree-phase Rectifiers

ScheduleThursday, 23.06.2011, 12:15 - 13:00 hrs

LanguageEnglish

Description

Chairman: James Wu, Ching Yun University, Taiwan

The goal of developing AC-DC converters with Isolation and Power Factor Correction feature in a single power

processing stage and without a mandatory fullbridge rectifier has for years eluded Power Electronics

researchers. Present AC-DC converters operated from a single-phase ac line are based on conventional PWMswitching method and process the power through three distinct stages: full-bridge rectifier followed by Boost

PFC converter and another cascaded isolated Full-Bridge DC-DC converter stage, which together use a total of

14 switches and three magnetic components resulting in efficiency limitation of around 90%, the present

platinum standard.

The new Hybrid switching methodTM and several resulting new AC-DC converter topologies will be introduced

which accomplish the same in a single- power processing stage designated as Single-phase rectifierTM

consisting of just three switches and a single magnetic component albeit at a much higher efficiency

approaching 98% and having a 0.999 power factor and 1.7% total harmonic distortion.

The ultimate solution is reached in an Isolated, Bridgeless, Three-phase AC-DC converter with Unity Power

Factor (designated here Three-Phase rectifierTM ), which converts the three-phase input power directly into a

desired high frequency isolated DC output voltage (48V for telecommunications, 12V for data centers, etc.)

again in a single power processing stage, but employing three isolation transformers operating at high

switching frequency of 100kHz. The intermediate 400V high voltage DC bus of conventional three-phase

AC-DC rectifiers is also eliminated resulting in direct cost and size benefits, while the high efficiency of 98%and other performance features of the above Single-phase rectifierTM solution are fully preserved.

The Three-phase rectifierTM, processes the power in parallel and equally through each phase, resulting in

additional size and cost savings. For example, a 1.2kW AC-DC converter is processing 400W power in parallel

through each phase. The conventional three-phase approaches are incapable to do that and must process the

full 1.2kW power through its second power processing stage, the Isolated DC-DC converter stage. Three-Phase

rectifierTM takes a full advantage of Teslas three-phase transmission system to convert constant

instantaneous input power directly to a constant DC output power, albeit isolated at high switching frequency,

with near unity power factor (0.999), low total harmonic distortion (1.7%), smaller size and lower cost but at

ultra high efficiency of 98%.

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6/2/2011