Power electronics in broader aspect actually controls the flow of power to make it suitable to be used by diverse type of instruments and appliances. The ability to control the flow of power is derived from using solid state switches along with their controllers.
The most interesting reduction technique of current harmonic is a PWM (active) rectifier (Fig. 1.3). Two types of PWM converters, with a voltage source output (Fig. 1.4) and a current source output (Fig. 1.5) can be used.
An alternative to the passive filter is use of the active PWM filter (AF), which displays better dynamics and controls the harmonic and fundamental currents. Active filters are mainly divided into two different types..
Many harmonic reduction methods exist. These techniques based on passive components, mixing single and three-phase diode rectifiers, and power electronics techniques as: multi-pulse rectifiers, active filters and PWM rectifiers (Fig. 1.1). They can be generally divided as:
List of Symbols used in Power Electronics books. Average value of the output DC voltage., Average value of the output DC current., Output dc power.,Output capacitor. The root mean square (rms) value of the ac voltage., The rms value of the ac current. Efficiency ( or Rectification ratio) of a rectifier.
Methods for limitation and elimination of disturbances and harmonic pollution in the power system have been widely explored. This problem rapidly build up with the increasing amount of electronic equipment (computers, radio set, printers, TV sets, motor control etc.).