Harmonics Current Reduction of a Single-Phase Rectifier Based on Injection Power at Field Side of the DC Motor

The AC electrical distribution systems operate at definite and limited levels of voltages and frequencies. Non-linear loads produce non-sinusoidal currents and voltages in the distribution systems. The controlled and uncontrolled single and three phase rectifiers have been utilized in many applications and different industrial fields. The purpose of these applications is to obtain controlled, systematic and smooth DC currents and voltages. These rectifiers generate harmonics in the supply current that negatively affects at the power quality and efficiency of the system. For this reason, reducing harmonics in the current waveform was under investigation by many research groups. Several methods are suggested for minimizing such harmonics, one of that is the harmonic current injection method, which is considered in this paper. In this paper two injection networks are applied at single phase bridge controlled and uncontrolled rectifier which loaded with DC motor. The first suggested injection network involves back to back thyristor in series with RLC circuit in order to adjust the value and phase of the second harmonic injection current. The second suggested injection network includes a new method to get advantages of using the injection power for supplying a field of DC shunt motor. The obtained results show that the total harmonic distortion is reduced by 79.26% with power factor closed to unity.