Abstract
M.Ing.
Power electronic systems are often treated purely as electronic circuits. This results in manufactured
systems that are electrically functional but not optimised in terms of packaging, temperature or volume.
This, in turn, results in low power densities.
The objective of this work is to investigate how a power converter should be built to obtain a high
power density while operating at high ambient temperatures. In doing so, the parameters affecting the
converter volume and thus the power density are identified.
In this work, a case study is considered, comprising a DC/DC converter operating in the automotive
environment. The specifications for the DC/DC converter identify the power density and high
temperature operation as the primary design objectives. The DC/DC converter is implemented in the
new dual voltage systems implemented in ultra-modern automobiles.
An unconventional converter structure is proposed to meet the electrical and thermal specifications.
The converter structure is divided into two sections, namely the active and passive components. The
two components share a combined cooling structure. Each of the components is analysed
fundamentally and with simulation packages on both an electrical and thermal level.
The active and passive components are implemented with material technologies such as open die semiconductors
on DCB substrates and high density planar inductors with specially designed cooling
structures. The two components take advantage of the thermal performance of the different
manufacturing technologies.
The complete converter structure is implemented and evaluated both electrically and thermally. The
converter structure achieves a power density of 170W/in3 while operating with a coolant temperature of
85°C.
Based on the case study, techniques are developed and suggestions are made that will result in the
power density and the operating temperature of the converter structure being increased. These
suggestions can also be used and implemented in the design and development of any high power
density and high operating temperature structure.