A power-equalized harmonic-elimination scheme for utility-connected cascaded H-bridge multilevel converters

Although fundamental frequency switching has been the preferred method for high-power medium-voltage multilevel converters, the technology of current generation power semiconductors has made it possible to use higher rates. In utility-connected applications, where a restricted modulation index range is usually sufficient, a main requirement is for very tight control over individual harmonics. For these reasons, this paper considers the application of selective harmonic elimination PWM (SHEPWM) with 5- or 7-level converters switching at low multiples of the fundamental frequency. An alternative approach for the calculation of multiple solutions of the firing angles is outlined, and is then applied in a modulation scheme that inherently equalizes the power flow from and to the individual DC energy sources. Results from computer simulations for a 7-level energy conversion system are presented in this paper.

[1]  D. V. Chudnovsky,et al.  Solving the optimal PWM problem for single-phase inverters , 2002 .

[2]  Xiaogang Huang,et al.  Direct-coupled multilevel cascaded series VAr compensators , 1997, IAS '97. Conference Record of the 1997 IEEE Industry Applications Conference Thirty-Second IAS Annual Meeting.

[3]  K. Sundareswaran,et al.  Evolutionary approach for line current harmonic reduction in AC/DC converters , 2002, IEEE Trans. Ind. Electron..

[4]  Richard G. Hoft,et al.  Generalized Techniques of Harmonic Elimination and Voltage Control in Thyristor Inverters: Part I--Harmonic Elimination , 1973 .

[5]  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).

[6]  Yen-Shin Lai,et al.  Virtual stage pulse-width modulation technique for multilevel inverter/converter , 2002 .

[7]  Zhong Du,et al.  Eliminating harmonics in a multilevel converter using resultant theory , 2002, 2002 IEEE 33rd Annual IEEE Power Electronics Specialists Conference. Proceedings (Cat. No.02CH37289).

[8]  Toshiji Kato,et al.  Sequential homotopy-based computation of multiple solutions for selected harmonic elimination in PWM inverters , 1999 .

[9]  Leon M. Tolbert,et al.  Multilevel converters for large electric drives , 1999 .

[10]  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.

[11]  G. Joos,et al.  Selective harmonic elimination and current/voltage control in current/voltage source topologies: a unified approach , 1999, IECON'99. Conference Proceedings. 25th Annual Conference of the IEEE Industrial Electronics Society (Cat. No.99CH37029).

[12]  Fang Zheng Peng,et al.  Multilevel inverters: a survey of topologies, controls, and applications , 2002, IEEE Trans. Ind. Electron..

[13]  H. L. Liu,et al.  Optimal PWM design for high power three-level inverter through comparative studies , 1995 .

[14]  S. Bernet,et al.  Recent developments of high power converters for industry and traction applications , 2000 .

[15]  G. Venkataramanan,et al.  DC bus ripple minimization in cascaded H-bridge multilevel converters under staircase modulation , 2002, Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344).