Interleaved selective harmonic elimination PWM for single-phase rectifiers in traction applications

Interleaved four-quadrant, single-phase rectifiers are widely used in traction applications as part of an AC-DC-AC conversion system. This paper presents selective harmonic elimination pulse-width modulation (SHE-PWM) patterns for single-phase interleaved PWM rectifiers based on both H-bridges and full-bridge NPCs (H-NPCs). SHE-PWM waveforms are defined so that the low-order harmonics of the combined voltage and input currents on the primary of the supply transformer are eliminated. The formulation of the problem and the acquisition of solutions becomes more challenging as the number of levels in the voltage waveform increases. Solutions based on reduced eliminated harmonics are proposed in order to increase the number of solutions as well as their continuity. It is shown that the proposed formulation improves the available solution space with minimal effect to the output. The theoretical analysis are verified through simulation studies.