Modern power electronics switching frequencies have became ever faster and are often in the two-digit kHz-range today. In semiconductors this leads to increasing loads, which considerably worsen the efficiency of a circuit and result in power dissipation. It was the objective of this diploma thesis to build a step down converter based on modern principles of power electronics to keep the ensuing load deep. The project includes the construction of the test circuit as well as testing its function. Parallel to the experiment, simulations were carried out, the results of which were compared with the conclusions of the measurements in the experiment.

Soft Switching is a possible alternative to solve the problem of unnecessary loads in semiconductors and thus minimize power dissipation. It represents a special type of switching process in which either the voltage or the current of the switch is circulating at zero at the time of switching off or switching on.

With the help of the simulations, the interrelatedness of the different voltage- and current-signals within the circuits become easily comprehensible and are then described in detail. The two circuits ZVS (Zero-Voltage-Switching) and ZCS(Zero-Voltage-Switching) were each structured into three parts: an input-part, a power-part and a control-part; the input part essentially consisting of three backup capacitors, which support fast current changes. The entire step down converter, marked as power-part, was built up on one board, to minimize interference. To establish connection and control of the IGBT-gate by a microcontroller a PWM-generator was developed.

The measurements showed that, due to additional expenditure on construction units, no better efficiency of the DC-DC-converter is achieved in soft switching. The advantages, however, consist of the longer life-span of the switch and in the smaller amount of harmonics, which can load the net asymmetrically.