Efficient Space-Vector Modulation Algorithm for Multilevel Converters with Low Switching Frequencies in the Devices

This paper presents a novel space-vector modulation scheme that can be processed quickly by a digital-signal processor, in addition to achieving minimum switching frequencies in the devices of the converter. The modulation algorithm takes advantage of symmetry in the space-vector diagram to process all the calculations within the first sextant. An equivalent reference vector in this sextant is used for the calculation of duty cycles and the definition of optimal sequences of vectors. By simply interchanging the final states of the legs of the inverter of this equivalent vector generates the original reference vector in the corresponding sextant. The total number of switching steps in the final sequences is preserved; thus, optimal sequences of vectors need only be defined in the first sextant. This strategy is especially attractive for multilevel converters in which the total number of vectors and sequences is very high. Furthermore, since multilevel converters are usually applied to high-power systems, reducing the switching frequencies of the devices is an important goal. Efficiency of the modulation algorithm is verified in the three-level converter by simulation and experiment

[1]  Dushan Boroyevich,et al.  A fast space vector modulation algorithm for multilevel three-phase converters , 1999, Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370).

[2]  Jie Zhang,et al.  Digital implementation of diode-clamped three-phase three-level SVPWM inverter , 2003, The Fifth International Conference on Power Electronics and Drive Systems, 2003. PEDS 2003..

[3]  P. Enjeti,et al.  Generalized discontinuous DC-link balancing modulation strategy for three-level inverters , 2002, Proceedings of the Power Conversion Conference-Osaka 2002 (Cat. No.02TH8579).

[4]  Humberto Pinheiro,et al.  Space vector modulation for voltage-source inverters: a unified approach , 2002, IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02.

[5]  D. Boroyevich,et al.  Limits of the neutral-point balance in back-to-back-connected three-level converters , 2004, IEEE Transactions on Power Electronics.

[6]  D. Boroyevich,et al.  Voltage-balancing strategies for diode-clamped multilevel converters , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[7]  P. Enjeti,et al.  Generalized Discontinous DC-link Balancing Modulation Strategy for Three-level Inverters , 2002 .

[8]  Dushan Boroyevich,et al.  Voltage-balance limits in four-level diode-clamped converters with passive front ends , 2005, IEEE Transactions on Industrial Electronics.