A New Carrier Based Neutral Point Potential Control Strategy for Three-Level NPC Converter

Modulation and neutral point (NP) potential effective balance are hot research topics for three-level NPC converters. A new modulation strategy and NP potential control based on the modulation strategy for three-level NPC converter is proposed in this paper. The basic principle of double modulation wave carrier-based PWM (DMWPWM) strategy is firstly analyzed and deduced. On the basis of DMWPWM strategy, a new modulation strategy is proposed. It deduces the analytical solution of the modulation wave, and added a model predictive control to achieve closed-loop control of the NP potential. Comparing with traditional DMWPWM strategy, it achieves a better control effect. Simulation verification shows that the proposed novel modulation strategy was simple and easy to implement, and it could not only achieve the NP potential balance under full modulation and full power factor but also reduce the switching loss of the devices and improve the system efficiency.