Optimum regulation of DC sources in cascaded multi‐level inverters

Purpose – The purpose of this paper is to introduce a new concept in selecting the values of the DC source voltages in cascaded multi‐level inverters in order to improve the output voltage THD.Design/methodology/approach – In cascaded multi‐level inverters, it is usually assumed that the DC sources have the same constant voltage and output harmonics minimization is accomplished by applying proper switching angles. Employing different DC voltages with proper ratios can result in further reduction of the harmonics. After formulation of the system, i.e. describing the inverter's output voltage components in terms of the switching angles and unequal DC source voltages, a rule is applied to obtain the step heights of the staircase output waveform (DC source voltages), so that the output waveform becomes as close to the required fundamental sine wave as possible. Substituting the obtained DC source voltages into the harmonics elimination equations results in a set of equations, which are functions of switching ...

[1]  Alfred Rufer,et al.  A three-phase multilevel converter for high-power induction motors , 1998 .

[2]  Peter K. Steimer,et al.  Five level GTO inverters for large induction motor drives , 1993, Conference Record of the 1993 IEEE Industry Applications Conference Twenty-Eighth IAS Annual Meeting.

[3]  P. W. Hammond,et al.  A new approach to enhance power quality for medium voltage AC drives , 1997 .

[4]  M. Hosseini Aghdam,et al.  Elimination of Harmonics in a Multi-Level Inverter with Unequal DC Sources Using the Homotopy Algorithm , 2007, 2007 IEEE International Symposium on Industrial Electronics.

[5]  Fang Zheng Peng,et al.  Multilevel converters-a new breed of power converters , 1995, IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting.

[6]  Fang Zheng Peng,et al.  A generalized multilevel inverter topology with self voltage balancing , 2000, Conference Record of the 2000 IEEE Industry Applications Conference. Thirty-Fifth IAS Annual Meeting and World Conference on Industrial Applications of Electrical Energy (Cat. No.00CH37129).

[7]  S. Mariethoz,et al.  Multisource DC-DC converter for the supply of hybrid multilevel converter , 2006, Conference Record of the 2006 IEEE Industry Applications Conference Forty-First IAS Annual Meeting.

[8]  Alfred Rufer,et al.  An overview of the technique of asymmetrical multilevel inverters , 2005 .

[9]  M.G. Lopez,et al.  Performance analysis of a hybrid asymmetric multilevel inverter for high voltage active power filter applications , 2003, IECON'03. 29th Annual Conference of the IEEE Industrial Electronics Society (IEEE Cat. No.03CH37468).

[10]  Qin Jiang, Thomas A. Lipo.  Switching Angles and DC Link Voltages Optimization for Multilevel Cascade Inverters , 2000 .

[11]  Leon M. Tolbert,et al.  Modulation index regulation of a multilevel inverter for static var compensation , 2003, 2003 IEEE Power Engineering Society General Meeting (IEEE Cat. No.03CH37491).

[12]  Vassilios G. Agelidis,et al.  Analysis of multicarrier PWM methods for a single-phase five level inverter , 2001, 2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230).

[13]  A. Mertens,et al.  Control Strategy for Multilevel Inverter with Non-ideal DC Sources , 2007, 2007 IEEE Power Electronics Specialists Conference.

[14]  Zhong Du,et al.  Elimination of harmonics in a multilevel converter with nonequal DC sources , 2005, IEEE Transactions on Industry Applications.