Design, modelling and simulation of three-phase front-end converter for unity power factor and reduced harmonics in line current

Low power factor and high harmonic content are the major drawbacks of conventional front-end rectifiers. Front-end converter is reported in this paper for three-phase system. A systematic design approach is presented for front-end converter and the modelling of the same is also described in detail in presented work. The control strategy for three phase front-end converter consists of inner current-loop and outer voltage-loop. The parameters for voltage control loop are derived from Unity Modulus (Magnitude Optimum) method. The power circuit of front-end converter with closed loop control is simulated in MATLAB for various steady state, transient and dynamic conditions. The proposed converter operates in forward power flow as well as in reverse power flow conditions. It is found that unity power factor is obtained for steady state as well as all dynamic and transient conditions. Irrespective of load conditions, constant dc output voltage is maintained demonstrating good voltage regulation and effectiveness of the proposed controller. It is also observed that %THD (Total Harmonic Distortion) of the supply current had drastically reduced in the reported system.