On the design of switch mode power supply

In this thesis, switch mode power supplies, differences between linear power supplies and switch mode power supply types are discussed. Widely used types of DC-DC converters depending on the input-output wave forms and circuit simulations using Pspice and B2 Spice are notably examined. Each type of DC-DC converter has DC input signal, switch, energy storage and filter elements. Filter elements smooth the ripple of the output. Without using filter elements, the output will be more unregulated. This is discussed by simulation of a basic type of converters. Every converter can be simulated by using a switch that is controlled by pulses. Although using filter elements, controlling the switch by pulses will comprise an unregulated output. There occur some losses because of the switching and components used in converters. To obtain more regulated output, some control circuits should be used. Pulse Width Modulation is the most important type. Some types of DC-DC converters are simulated by adding PWM control circuits. Diodes that are used in switch mode power supplies are reverse or forward biased depending on the condition of the switch. If a forward biased diode is suddenly switched to reverse bias, the conduction will continue in the reverse direction for a short interval called the reverse recovery time. Therefore, they should be selected with minimal recovery times. Ideal diode should have no reverse recovery time, but practically this can not be possible. The aim of choosing proper diode is to minimize this reverse recovery time.