Single Phase Neutral Point Diode Clamped Active Rectifier - A Literature Review

The ac-dc conversion is used increasingly in a wide diversity of applications: power supplies for microelectronics, household electric appliances, electronic ballasts, battery charging, dc motor drives, power conversion, etc. As shown in figure below ac- dc converters can be classified to different topologies working with low switching frequency (line commutated) and other topologies which operate with high switching frequency. The simplest line- commutated converters use diode to transform the electrical energy from ac to dc. In this paper the analysis of single- phase neutral point active rectifier is proposed to reduce harmonics from the supply and also to achieve unity power factor. Here different PWM techniques are used and the line current command is derived from a Dc link voltage regulator and an output power estimator. The hysteresis current controller is used to track the line current command. To balance the neutral point voltage, a capacitor voltage compensator is employed.