3. Power Converters A power converter, consisting of a pattern of power semiconductor switches and one or several passive components, helps to convert and control electrical power from ac to dc, dc to dc, dc to ac, or ac to ac [1]. Converter development has essentially followed device progression. Certainly, the most common type of converter operates on a utility system. Diode or thyristor-based converters distort the ac line current and create utility system power quality problems. It is more economical to solve these problems by using a PWM-type front-end converter with self-controlled devices (such as power MOSFETs, IGBTs, GTOs or IGCTs) that shape the line current to be sinusoidal, and the displacement power factor (DPF) can be programmed to be unity, leading or lagging. In addition, the line voltage sag problem can easily be compensated. Considering the present trend, it appears that eventually phase-controlled converters and cycloconverters will become obsolete for operation in utility systems. Converting dc to ac voltage is known as inverting. It is carried out by voltage-fed and current-fed inverters, with the former superior in overall figure-of-merit considerations. Therefore, this class of inverters has been accepted almost universally for general power processing applications. Voltage-fed inverters can be two- or multilevel types, depending on the level of handling power. Recently, research into multilevel inverters and their applications has been very prominent in literature [3, 4]. Multilevel inverters with higher numbers of levels are vital for handling higher power at high voltage. In general, their applications could comprise high-power motor drives and utility system applications (such as STATCOM and HVDC inverters). The inverter is normally maneuvered in PWM mode for motor drive, but in stepped-wave mode (with coupling transformers) for STATCOM [4–6]. Flexible ac transmission systems (FACTS) [3] are basically an industrial electronic method of regulating the bus voltage and controlling the flow of active (P) and reactive (Q) power (often called unified power flow controlling) in the transmission system of a utility grid. Since the transient response of STATCOMs for supplying and absorbing energy pulses is very fast, the units can also control transient stability and generator oscillation problems of the utility system. FACTS applications will continue to grow in future with higher converter levels and higher power ratings as we gain more experience in this area [2, 3]. In a motor drive, high dv/dt deteriorates machine insulation, causes bearing current problems and machine terminal voltage boost when there is a long cable between the inverter and the motor. To overcome these problems, soft-switched converters have been proposed. Soft-switched power conversion is considered one of today’s hot applications. It is a high-frequency link power conversion, where the load requires galvanic isolation from the source through a high-frequency transformer [1-4]. One popular application area of soft-switched converters is resonant-link dc–dc converters. Future emphasis on converters will be mainly in industrial electronic building block integration, automated design, simulation, manufacturing and testing