Harmonic reduction of input current of boost-type rectifier using sigma-delta modulation schemes

This paper presents sigma-delta modulation (SDM) schemes as the powerful approach to achieve sinusoidal input current of a boost-type rectifier (BTR). The dominant low-frequency harmonics of the input current in the BTR are eliminated by virtue of the switching pulse patterns of the SDM schemes which are configured by a long switching on-state duration of boost switcher at the starting of each half-cycle. The difference between the sinusoidal reference and real input current of the BTR is estimated at the starting of each half-cycle. The switching pulse patterns of the SDM schemes near input current zero crossing are compared with that of a fixed switching frequency PWM. The performances of the SDM schemes were validated on a 1.6 kW BTR using computer simulations. The current THD values confirm that the BTR with the SDM schemes yield more sinusoidal input current than that with the fixed switching frequency PWM scheme.