Smooth Switch Modulation for DC-link Voltage Balance in Three-Phase Three-Level Neutral Point Clamped Cascaded Rectifier

This paper presents a modulation strategy for DC-link voltage balance in three-phase three-level neutral point clamped cascaded rectifier (3LNPC-CR). As the vital component of power electronic transformer (PET), the reliability of 3LNPC-CR is important. Consequently, a smooth switch modulation (SSM) strategy is proposed to balance the DC-link voltage. This strategy put all switch states into a lookup table, which can be selected as needed to balance the DC-link voltage. Last but not the least, the result of simulation is illustrated in this paper to demonstrate the correctness of the proposed DC-link voltage balance strategy.