Development of a Modified SPWM Control Inverter for Tidal Current Generation System

This paper proposes a modified sinusoidal pulsewidth modulation (SPWM)control single-phase inverters for the tidal current generation system. In general, a two-stage configuration is used to convert the generating AC power from the tidal current generator to DC power by a rectifier and transfer the DC power into AC power by an inverter to provide a stable voltage source. It is noticed that a small size capacitor of the rectifier is possible and the discontinuous current can be improved. However, a small size capacitor implies the higher voltage ripple and results in a lots of low-order voltage harmonics of the inverter with traditional SPWM control. Therefore, a modified modulation control strategy is developed in this paper. The proposed inverter has lower total harmonic distortion (THD)of the output voltage with high input voltage ripple. The low-order harmonics of output voltage can be reduced effectively and the THD is less than 2.5% in the experiments.