Selective harmonic elimination for multilevel inverters with unbalanced DC inputs

Selective harmonics elimination for the staircase voltage waveform generated by multilevel inverters has been widely studied in the last decade for medium and high voltage applications. Most published methods on this topic are used for balanced multilevel inverters with the same dc voltage magnitude. In the proposed method, equal area criteria and harmonics injection are used for totally unbalanced multilevel inverters. Regardless of how many voltage levels are involved, only four modified equations are proposed in the basic method. To eliminate the harmonic components in unbalanced conditions, the problems of the basic method are discussed for a wide range of modulation indices. Then, a full set of solutions is proposed based on the combination of optimal PWM and the four-equation based method for a wide range of modulation indices in unbalanced conditions.

[1]  V. Agelidis,et al.  Selective Harmonic Elimination PWM Control for Cascaded Multilevel Voltage Source Converters: A Generalized Formula , 2008, IEEE Transactions on Power Electronics.

[2]  Leon M. Tolbert,et al.  Multilevel converters for large electric drives , 1998, APEC '98 Thirteenth Annual Applied Power Electronics Conference and Exposition.

[3]  J. Chiasson,et al.  The Use of Power Sums to Solve the Harmonic Elimination Equations for Multilevel Converters , 2005 .

[4]  V. Agelidis,et al.  A Five-Level Symmetrically Defined Selective Harmonic Elimination PWM Strategy: Analysis and Experimental Validation , 2008, IEEE Transactions on Power Electronics.

[5]  Patrick Wheeler,et al.  A power-equalized harmonic-elimination scheme for utility-connected cascaded H-bridge multilevel converters , 2003, IECON'03. 29th Annual Conference of the IEEE Industrial Electronics Society (IEEE Cat. No.03CH37468).

[6]  J. K. Steinke,et al.  Control strategy for a three phase AC traction drive with three-level GTO PWM inverter , 1988, PESC '88 Record., 19th Annual IEEE Power Electronics Specialists Conference.

[7]  Zhong Du,et al.  Elimination of harmonics in a multilevel converter using the theory of symmetric polynomials and resultants , 2005, IEEE Transactions on Control Systems Technology.

[8]  Damoun Ahmadi,et al.  Optimal PWM method based on harmonics injection and equal area criteria , 2009, 2009 IEEE Energy Conversion Congress and Exposition.

[9]  Brendan Peter McGrath,et al.  Multicarrier PWM strategies for multilevel inverters , 2002, IEEE Trans. Ind. Electron..

[10]  L.M. Tolbert,et al.  5 kW Multilevel DC-DC Converter for Hybrid Electric and Fuel Cell Automotive Applications , 2007, 2007 IEEE Industry Applications Annual Meeting.

[11]  P. Pillay,et al.  Multilevel selective harmonic elimination PWM technique in series-connected voltage inverters , 1998, Conference Record of 1998 IEEE Industry Applications Conference. Thirty-Third IAS Annual Meeting (Cat. No.98CH36242).