A fuzzy-controlled active front-end rectifier with current harmonic filtering characteristics and minimum sensing variables

A control strategy which allows conventional voltage-source current-controlled (VSCC) pulsewidth modulation (PWM) rectifiers to work simultaneously as active power filters is presented. The proposed control strategy also allows compensating the system power factor and compensating unbalanced loads. The measurement and/or calculation of the harmonics and reactive power are not required, making the proposed control scheme very simple. The active front-end rectifier acts directly on the mains line currents, forcing them to be sinusoidal and in phase with the mains voltage supply. To improve the dynamic of the system, the amplitude of the current is controlled by a fuzzy system, which adjusts the de-link voltage of the PWM rectifier, The strategy is based on connecting all the polluting loads between the PWM rectifier and their input current sensors, The main advantages of this approach are the following: 1) there is no need to install a specially dedicated active power filter; 2) it also works simultaneously as power factor compensator; and 3) no special and complicated calculations are required for harmonic elimination. The viability of the proposed active front-end rectifier is proved by simulation and with experimental results obtained from a 2-kVA PWM prototype.