A New Dc-link Capacitor Voltage Balancing Method for Three-level SVM Strategies Based on Two-level Space Vector Diagram

This paper presents a new dc-link capacitor voltage balancing method for three-level Space Vector Modulation (SVM) strategies that are based on the space vector diagram of two-level inverters. The proposed method uses the time distribution of the local two-level zero vectors to achieve dc-link voltage balancing. It redistributes the zero vector times based on the magnitude and direction of the dc-link capacitor voltage deviations. The performance of the proposed capacitor voltage balancing method is compared with the conventional three-level SVM capacitor voltage balancing method that uses three-level redundant small vectors. The proposed method achieves significantly lower neutral-point voltage ripple compared to the conventional three-level SVM capacitor voltage balancing method for a wide range of modulation indices and load power factor values. Moreover, the code size and execution time are reduced by approximately 30 percent for use in microcontrollers.