DC Capacitor Voltage Control Strategy of Five-level NPC Converter Based on Hybrid SVPWM

Taking the five-level Neutral Point Clamped (NPC) converter as the research object, aiming at the problem of unbalanced voltage of the DC side capacitor caused by the traditional SVPWM, the hybrid SVPWM capacitor voltage balance control strategy is adopted. In the low modulation area, a five-level DC side capacitor voltage self-balancing strategy is proposed. Through the voltage deviation and the direction of the flowing current, the real-time dynamic Select the optimal redundancy state, and propose a control strategy based on active current to achieve DC-side capacitor voltage balance in the high modulation region. By judging the direction of the active current and the deviation of the capacitor voltage, combining the relationship between the capacitor current and the phase current and all the five-stage switching sequences, the optimal switching sequence is selected so that the maximum capacitive voltage deviation is reduced to zero as much as possible. The effectiveness of the modulation method proposed in this paper is proved by experimental simulation.