Space vector modulation strategy for an eight-switch three-phase NPC converter

Abstract

A three-phase neutral point clamped (NPC) converter is presented for power factor correction and dc-link voltage regulation. A simplified space vector pulsewidth modulation scheme (SVPWM) is adopted to track line current commands. Using a simplified SVPWM algorithm, the calculated time for the time duration of voltage vector is reduced. The adopted NPC converter has less power switches compared with the conventional three-level NPC converter. Only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used in the circuit configuration. Based on the proposed control algorithm, a reference voltage vector is generated on the ac terminal for drawing the sinusoidal line currents with unity power factor. Computer simulation and experimental results based on a laboratory prototype are presented to verify the validity and effectiveness of the proposed control strategy.