A Phase-Controlled 12-Pulse Rectifier with Unity Displacement Factor without Phase Shifting Transfor - Applied Power Electronics Conference and Exposition, 1998. APEC '98. Conference Proceedings 1998.,

This paper presents a three-phase 12-pulse phasecontrolled rectifier with unity displacement factor, low line current harmonic content, two quadrant operation and absence of phase shifting transformer. The circuit is composed by two three-phase 6-pulse rectifiers parallel connected by four balancing reactors. One is a conventional thyristor rectifier with a lag firing angle (a). The other is an active rectifier composed by GTOs or IGBTs and diodes, operating with a lead (and symmetrical) firing angle (-a). The 12-pulse operation with line frequency modulation provides a 5-level line current with reduction or cancellation of certain harmonics. Circuit operation, theoretical analysis, key equations, along with experimental and simulation results are presented.