Untersuchung und beurtailung det auswirkunken einer synchronen Gleichrichtung auf das betriebsverhalten eines Klauenpol-Generators fur Kraftfahrzuege

Abstract

In this thesis work, a first step in the subject Synchronous rectification for automotive generators has been done. After an examination of the physical generator basics, two rectification techniques, the diode and the synchronous MOSFET ones, have been researched. The influence of the synchronous rectification on the electrical machine and a detailed examination of the power losses generated in the electrical machine with both rectification techniques take center stage. In order to graphically represent these differences, data field measurements have been carried out: by these means, the efficiency, the power losses and the output power could be estimated along the whole operating range of the electrical machine. The so determined differences in power losses for both of the systems build up the basics for the investigation of the vehicle fuel consumption. Thus, the fuel consumption benefits have been theoretically evaluated, simulated and in a prototype vehicle measured. With the aid of these vehicle measures, it has been possible to prove that the calculated variation in power losses actually bring a fuel consumption reduction in the vehicle. The order of magnitude of the fuel savings has been appreciable for the test cycle NEFZ, as well as for costumer relevant driving cycles (city, overland or mixed). An additional benefit of the synchronous rectification when implemented in the vehicle is also significant: the maximal output power of the generator is largely increased in the idle range. Through this, the generator size installed in the vehicle could be smaller, what could partially compensate the additional costs of the synchronous rectifier.