Research on Neutral-point Balancing Control for Three-level NPC Inverter Based on Correlation between Carrier-based PWM and SVPWM

Based on inherent correlation between the carrier-based PWM and SVPWM for three-level inverter, this paper presents a new modulation approach for the control of the neutral-point voltage variation in the three-level neutral-point-clamped voltage source inverter. The new modulation approach realizes the control of inverter neutral-point current by modifying redundant small vectors pairs distribution factor, only requiring the information of dc-link capacitor voltages and three-phase load currents, which is convenient to apply and is compatible of digital computer realization. The effectiveness of proposed control approach is verified by simulation and experiment results