I.W. Hofsajer

Interleaving optimization in synchronous rectified DC/DC converters

Interleaving in synchronous rectifiers can lead to reduced losses in both the active and passive components. However, this depends on selecting the correct number of phases and the correct phase inductance for a particular application and requirements. In this paper optimizing the number of phases and the phase inductance is considered to maximize the interleaved synchronous rectifiers efficiency over the desired operating range. To do this, the RMS currents and losses in the bus capacitors, the phase inductances and the switching devices as a function of the number of phases and duty cycle are considered. Generic equations are presented and used to predict the RMS currents in the passive components with some non-intuitive results especially concerning the bus capacitors. It is shown in the paper, that the optimum number of phases is dependent on the converter parameters such as the phase inductance and operating requirements. Practical results are presented confirming the synchronous rectifier loss model.

Exploiting the third dimension in power electronics packaging

A common feature of current power electronics packaging is that technologies and concepts of low power electronics are adapted and consequently the circuit remains essentially two dimensional. Exploitation of the third dimension, namely the height creates volume which is essential for the energy storage and conversion functions and also makes compact packaging possible. However, as the height and therefore the volume increases, thermal considerations become increasingly important. A concept involving multiple layers of electromagnetic materials and switching function layers is proposed. A module is encapsulated in a ferrite and copper casing ensuring low EMI and EMS. The module has both electrical and thermal ports to interface with its environment. The concept is illustrated using two prototype DC to DC power converters.

A new manufacturing and packaging technology for the integration of power electronics

In this paper, a new manufacturing and packaging technology for power electronics is described and evaluated. This technology is required to fulfil the need for cost effective, mass market, power electronics products. The packaging is based on a new planar technology that is well suited to mass production. One of the features of the packaging is the incorporation of the entire power converter inside the magnetic structures of the converter. This leads to very good magnetic shielding, as well as other benefits, but also gives rise to other problems. The technology is illustrated with the integration of an experimental dual active bridge DC-DC power converter. The design as well as the construction of the converter is described.

High density packaging of the passive components in an automotive DC/DC converter

In this paper a very high power density DC/DC converter module for automotive applications is investigated. The 14 V/42 V converter is specified to operate at a power level of 2.1 kW with a water cooled heatsink at 85/spl deg/C. The design and implementation of very high density passive components is discussed. Using the results of the passive component design, a prototype converter is built achieving a final power density of 170 W/in/sup 3/. The thermal performance of the passive components and converter module under different electrical and thermal excitations is investigated and recorded. Results are presented over the full excitation range.

Integrated technology and performance for multi-kilowatt power electronic converters-an evaluation

This paper presents an overview of the current state of the technology for electromagnetic integration of high power electronic converters. Some of the materials technologies needed for manufacture are described. As an example a completely integrated experimental multi-kilowatt resonant DC-DC power converter is discussed, together with some problems encountered and their solution. Experimental results are also given. A possible extension of the technology to hard switched, but snubbed and clamped power converters is discussed. Some of the thermal problems together with a thermal analysis are addressed. Conclusions about the technology are drawn and possible future developments investigated.<<ETX>>

A comparative study of some electromagnetically integrated structures in hybrid technology

A research program into the electromagnetic integration of power electronics is evaluated to date. The integration is approached from an energy processing point of view, and the structures developed are predominantly planar in nature. The materials technology developed in order to construct integrated structures is discussed. A number of prototypes that were constructed are presented and discussed. The prototypes vary from the integration of a few reactive components to fully-integrated power converters.

Integrated output filter and diode snubber for switchmode power converters

In this paper, a planar integrated network consisting of a diode rectifier, RC snubber and LC filter is presented. The application of this integrated network in existing topologies is discussed. The design and analysis of the different subcircuits of the integrated network are described, in terms of modelling and physical construction. Some of the materials and manufacturing techniques of the integrated network are discussed. A prototype is constructed and evaluated experimentally.<<ETX>>

A planar integrated RCD snubber/voltage clamp

An electromagnetically integrated resistor-capacitor-diode (RCD) snubber/voltage clamp is described which uses a planar construction technique. The design and construction are described, and the performance is verified experimentally. This integrated RCD snubber/voltage clamp can be used to replace a conventional snubber/clamp constructed from discrete components. It offers a wide variety of advantages over its discrete counterpart. The stray inductance in the component has been reduced to the absolute minimum. Thermally, the planar resistive structure has an advantage over wire wound resistors, due to a larger cooling area. The planar nature of the structure lends itself to mass production in a similar manner as integrated signal electronics, leading to cost reduction. The use of integrated components in the large-scale production of power electronic equipment can lead to a reduction in cost due to the assembly of fewer discrete components.<<ETX>>

A new approach to low conversion ratio DC-DC converters

Low output voltage, nonisolated, DC-DC converters are the focus of much investigation. The primary application of these converters is as the voltage regulating module of low voltage microprocessors. Efficiency, power density as well as dynamic response are the primary performance criteria that are optimised. A new proposed DC-DC conversion system is presented making possible a reduction in switch RMS current ratings and both the input and output filter capacitance. This in turn leads to an increase in power density. Four bi-directional DC-DC converter topologies suitable for high power, low conversion ratios are presented, two of which employ the proposed DC-DC system and two for comparison. The direct partial voltage regulation module (DPVRM) proposed is seen to have the highest efficiency. Experimental results from the four topologies are shown and critically compared.

Volume considerations of planar integrated components

Planar magnetic components find widespread application and numerous advantages are cited of planar components over conventional wire-wound components. These advantages come at the expense of an increase in the volume of the magnetic material required. This disadvantage may be offset to some extent by enhancing the capacitance between the winding layers and utilizing the resulting structure in a resonant topology. In this paper the volume considerations of such planar components are addressed.