Měnič se zvýšenou účinností pro automobilové aplikace

Abstract

The Ph.D. thesis is dealing with evaluation of properties of soft switched converters for their utilisation in hybrid electric vehicles structures. Therefore, the thesis is concerned with the converters that use resonant behaviour for achievement lower switching losses. In the first part of the thesis is introduced general description of drive unit structures that uses cooperation of fuel cell and ultra-capacitors. In this section are also shown the properties of fuel cell and ultra-capacitor and their function principles, including their current utilisation in electric vehicles. The introduction to soft switching is given in chapter 4. There are clarified basic principles of soft switching – zero-current switching (ZCS) and zero-voltage switching (ZVS). Further, the overview of resonant topologies, semiconductor switches, elements of resonant circuits and control methods of resonant converters is provided. The main part of the thesis is dealing with detailed analysis of resonant behaviour of quasiresonant converters, multi-resonant converters and bi-directional half-bridge resonant converter, including criterion evaluation of their transfer function. In the last section is made the design of above mentioned resonant converters. Their functionality is illustrated by simulation results from PSpice software. The experimental results chapter stated the chosen specific properties of resonant converters, which were obtained by measurement at laboratory resonant converter model. The experimental data are compared with simulation results.