PWM rectifier is an AC to DC power converter, which is implemented using forced commutated power electronic semiconductor switches. Conventional PWM converters are used for wind turbines that have a permanent-magnet alternator.
Today, insulated gate bipolar transistors are typical switching devices. Different from diode bridge rectifiers, PWM rectifiers achieve bidirectional power flow. In frequency converters this property makes it possible to perform regenerative braking. PWM rectifiers are also used in distributed power generation applications, such as micro turbines, fuel cells and windmills.
The major advantage of using pulse width modulation technique is the reduction of higher order harmonics and we can also control the magnitude of the output voltage.we can also improve the power factor by forcing the switches to follow the input voltage waveform using a PLL loop