Analysis and simulati̇on of forward converter with a new active snubber cell

Pulse Width Modulation is a common control method implemented on DC-DC converters. It is provided to high power density, fast transient response and ease of control via this method. Power density can be expressed as the ratio between obtained power and size of converter (m3) or the ratio between obtained power and weight of converter (kg). To increase power density of a DC-DC Converter can be possible by increasing switching frequency but it is also increased switching losses when increased switching frequency. For this reason, the switching frequency can be increased by using soft switching (SS) techniques instead of hard switching (HS). If soft switching methods need to summarize with a simple classify, it can be expressed under 4 header such as; zero voltage switching, zero current switching, zero voltage transition, zero current transition. In literature, there are many DC-DC PWM Converters and one of them is Two-Switch Forward Converter. This converter can be used effectively in low and middle powers. One of the important disadvantage of this converter is limited duty cycle with %50. Duty cycle is described as ratio between conduction time and period in a constant frequency. Power density can be also increased by increasing duty cycle. DC-DC converters can be supplied with AC Source via rectifier circuits. There is a storage capacitor which is in placed output of these rectifier circuits in order to re-shape DC voltage. In DC-DC converters, for example, Two-Switch Forward Converter, this storage capacitor determines to maximum duty cycle. Larger duty cycle ratio causes smaller storage capacitor values and it also decrease the cost of converter. In this thesis, a new snubber cell is developed in order to increase the power density, the duty cycle and the efficiency for Two-Switch Forward Converter. Increasing duty cycle causes to make the storage capacitor smaller, which is used for re-shaping to DC line. That is also one of the goals for designed converter in this thesis. It is also expected to decrease EMI noise for converters implementing soft switching methods but this is not included in scope of the thesis. In order to make a comparison, it is designed a Forward converter which has 100 kHz switching frequency, 25 volts Output voltage, 1000W Output power and designed a forward converter with a new active snubber cell which has 100 kHz switching frequency, 25 volts Output voltage, 1800W Output power. It is proved by using Psim software that working with higher duty cycle, making storage capacitors value smaller which is placed out of rectifiers, working with soft switching. In order to make the components in Psim software more realistic, it has been used their datasheets. For same reason, after the magnetic components of the converter are simulated in ANSYS software, they have been transferred to Psim software.