Natural Balance of Multicell Converters: The General Case

This paper focuses on the development of the natural balancing theory for the p-cell case. It describes the relationship between the models for different numbers of cells in a generic model for a p-cell multicell converter. The model discussed is based on the same principles that were used to develop the two-cell model in , except that the mathematics is much more involved. The same conclusions that were found to be true for the two-cell case was also found to be true for the general case of p cells. These conclusions include that the natural balancing mechanism of multicell converters depends on the overlap of the groups of harmonics of the switching function as well as on the load impedance. It will also be shown that the self-balancing mechanism ensures safe operation under most operating conditions where a high enough switching frequency is chosen and the load is not purely reactive. Two new aspects of the balancing theory were identified in the p-cell case: 1) for fixed duty-cycle modulation there exists certain values of the duty-cycle that causes the natural balancing mechanism to fail and 2) for p-cell converters the balance booster concept can be extended to a number of balance boosters tuned to multiples of the switching frequency. A "DesignTool" based on the balancing theory was developed to aid practicing engineers in designing multicell converters

[1]  Charles R. Johnson,et al.  Matrix analysis , 1985, Statistical Inference for Engineers and Data Scientists.

[2]  Carl D. Meyer,et al.  Matrix Analysis and Applied Linear Algebra , 2000 .

[3]  Hendrik Du Toit Mouton Analysis and synthesis of a 2 MVA series-stacked power-quality conditioner , 1999 .

[4]  T.A. Meynard,et al.  Natural Balance of Multicell Converters: The Two-Cell Case , 2006, IEEE Transactions on Power Electronics.

[5]  J.H.R. Enslin,et al.  High performance DSP/FPGA controller for implementation of computationally intensive algorithms , 1998, IEEE International Symposium on Industrial Electronics. Proceedings. ISIE'98 (Cat. No.98TH8357).

[6]  T.A. Meynard,et al.  Stability analysis of multicell converters , 2004, 2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590).

[7]  Hendrik du T. Mouton,et al.  Natural balancing of three-level neutral-point-clamped PWM inverters , 2002, IEEE Trans. Ind. Electron..

[8]  John G. Proakis,et al.  Digital Signal Processing: Principles, Algorithms, and Applications , 1992 .

[9]  Philippe Carrere Étude et réalisation des convertisseurs multicellulaires série à IGTB : équilibrage des condensateurs flottants , 1996 .

[10]  T.A. Meynard,et al.  Natural balance of multicell converters , 2003, IEEE 34th Annual Conference on Power Electronics Specialist, 2003. PESC '03..

[11]  Hd.T. Mouton,et al.  Natural balancing of series-stacked power quality conditioners , 2003 .

[12]  G. Strang Introduction to Linear Algebra , 1993 .

[13]  R. H. Wilkinson,et al.  Voltage unbalance in the multicell converter topology , 2002, IEEE AFRICON. 6th Africon Conference in Africa,.

[14]  E. Kreyszig Introductory Functional Analysis With Applications , 1978 .

[15]  R. Bhatia Matrix Analysis , 1996 .