This paper reviews state-of-the-art approaches for galvanically isolated DC-DC converters based on radio frequency (RF) micro-transformer coupling. Isolation technology, integration level and fabrication issues are analyzed to highlight the pros cons of fully integrated (i.e., two chips) multichip systems-in-package (SiP) implementations. Specifically, different basic isolation technologies com...

The number and diameter of strands to minimize loss in a litz-wire transformer winding is determined. With fine stranding, the ac resistance factor can be decreased, but dc resistance increases as a result of the space occupied by insulation. A power law to model insulation thickness is combined with standard analysis of proximity-effect losses to find the optimal stranding. Suboptimal choices ...

In the early days of superconductivity, Ivar Giaver discovered that it was possible to make a novel DC transformer by using one superconductor to drag vortices through another. An analogous effect was predicted to exist in quantum Hall bilayers and has recently been discovered experimentally by Eisenstein’s group at Caltech. Similarly, new experiments from the Caltech group have demonstrated th...

A new family of ac–dc converters is derived which integrate the functions of low-harmonic rectification, low-frequency energy storage, and wide-bandwidth output voltage control into a single converter containing one, two, or four active switches. These converters utilize a discontinuous conduction mode input inductor, an internal energy storage capacitor, and transformer secondary circuits whic...

For hybrid electric vehicles, the batteries and the drive dc link may be at different voltages. The batteries are at low voltage to obtain higher volumetric efficiencies, and the dc link is at higher voltage to have higher efficiency on the motor side. Therefore, a power interface between the batteries and the drive’s dc link is essential. This power interface should handle power flow from batt...

In this paper new autotransformer arrangements with reduced kVA capacities are presented for harmonic current reduction and to improve AC power quality of high current DC power supplies. A twelve-pulse AC to DC rectifier is proposed employing only 0.18Po (pu) transformer kVA. The 5th and 7th harmonics are absent in the utility line currents. Further it is shown that conventional 12pulse operati...