Power conversion architecture for grid interface at high switching frequency

Abstract

Abstract-This paper presents a new power conversion architecture for single-phase grid interface. The proposed architecture is suitable for realizing miniaturized ac-dc converters operating at high frequencies (HF, above 3 MHz) and high power factor, without the need for electrolytic capacitors. It comprises of a line-frequency rectifier, a stack of capacitors, a set of regulating converters, and a power combining converter (or set of power combining converters). The regulating converters have inputs connected to capacitors on the capacitor stack, and provide regulated outputs while also achieving high power factor, with twice-line-frequency energy buffered on the capacitor stack. The power combining converter combines power from the individual regulated outputs to a single output, and may also provide isolation. While this architecture can be utilized with a variety of circuit topologies, it is especially suited for systems operating at HF (above 3 MHz), and we introduce circuit implementations that enable efficient operation in this range. The proposed approach is demonstrated for an LED driver operating from 120 Vac, and supplying a 35 V , 30 W output. The prototype converter operates at a (variable) switching frequency of 5-10 MHz and an efficiency of > 93%. The converter achieves a displacement power density of 130 W/in 3 , while providing a 0.89 power factor, without the use of electrolytic capacitors.

A Performance of the Soft-Charging Operation in Series of Step-Up Power Switched-Capacitor Converters

“…To achieve a superior efficiency achievement purpose, it is recommended that SC converters are designed with resonant soft-switching techniques. However, designing resonant SC converters requires additional components, and hence a reduction in the power density is possible [9][10][11][12][13][14][15][16][17].…”

Measurements and Performance Factor Comparisons of Magnetic Materials at High Frequency

“…This is equal to 1.5δ at 28 MHz at room temperature in copper, indicating in this case that magnetic materials could be evaluated using F 1 2 for frequencies up to 28 MHz. The lower power of f ( 1 ⁄2 instead of 3 ⁄4) in the performance factor for this case indicates the diminishing value of litz wire over the HF frequency range, and in practice, litz wire is not usually worthwhile above the low end of the HF range (though it has been used effectively in the 5-10 MHz range, e.g., [23], [24]). …”

High-frequency isolated ac-dc converter with stacked architecture

“…Here we present an isolated ac-dc converter with a stacked architecture [14], [15] and utilizing a inverted resonant transition buck converter and a capacitively-aided isolated bus converter [16] to provide galvanic isolation and voltage transformation. The proposed ac-dc converter addresses converter miniaturization through high-frequency operation while main- taining good efficiency, and achieves reasonably high power factor consistent with line harmonic requirements [5], while dynamically buffering twice-line frequency energy at moderate voltages with large voltage swings [17]- [23].…”