Thesis Defense - Özlem Özden (MSEE)

Özlem Özden- M.Sc. Electrical Electronics Engineering

Asst.Prof. Ahmet Tekin - Advisor

HIGH FREQUENCY POWER SUPPLY DESIGN

Date: 20.08.2019

Time: 09:00

Location: AB1 412

Thesis Committee: 

Asst. Prof. Ahmet Tekin,  Özyeğin University

Asst. Prof. Göktürk Poyrazoğlu,  Özyeğin University

Asst.Prof. Özkan Akın, Ege University

Abstract

Portability, power density, and energy efficiency are among the hottest topics of today. Therefore, the need for higher power-capacity, smaller size, and higher efficiency power supply is increasing day by day. At this point, the switching frequency has the most noticeable effect. By the help of using high switching frequency, the converter size
and weight can be reduced significantly; in other words, the power density can be increased. In addition, the high switching frequency decreases capacitor value and therefore electrolytic capacitors can be eliminated. As a result of this, the reliable ceramic type capacitor can be employed.
The Switch Mode Power Supply (SMPS) converters utilize switching frequency as the basic feature of these converters and they have gained significant attraction recently due to having low weight, volume, cost advantages. There are conventional SMPS topologies in the literature such as buck, boost, buck-boost, flyback etc., which
are hard switched topologies and their switching frequency can reach only 100 kHz levels. Increasing the switching frequency of these type converters raises the losses inevitably. Hence, the switching frequency has to be chosen low for limiting the loss. As a result of this, these conventional topologies require a large capacitor and inductor values. In order to solve this problem, resonant converters which have soft switching behavior are proposed in the literature, and the switching frequency can reach up to MHz level. Among these converters, class E type resonant converter has a single switch which source (for MOSFET) has a ground connection hence it is easy to drive. Additionally, the class E converter has an easy design advantage because it uses low number of components. Hence, in this thesis, the class E resonant converter is chosen for these advantages. In this study, a class E DC/DC converter is analyzed, simulated and implemented for obtaining 24 V/60 W output from 48 V input voltage.
Additionally, 0.5 MHz and 1.2 MHz switching frequency is selected for studies. On the other hand, the analysis was proven by PSIM simulations and experiments. From the experiments, it was seen that electrolytic capacitors can be eliminated by high switching frequency and ceramic type capacitors can be used instead of electrolytic counterparts.