Natural balancing of three-level neutral-point-clamped PWM inverters

This paper explores the natural balancing mechanisms of the three-level neutral-point-clamped (NPC) multilevel inverter. An equivalent circuit of the three-level NPC inverter is derived that facilitates an understanding of the balancing mechanisms. This is followed by a detailed analysis of the balancing mechanisms. The theory is applied to a three-level NPC inverter under vector control. It is shown that this inverter possesses natural balancing mechanisms in which the load impedance and spectra of the switching functions play an important role. Finally, it is illustrated how the natural balancing can be enhanced by using a passive balancing circuit which provides a low impedance at the sampling frequency.

[1]  H. Akagi,et al.  Balancing theory of series-stacked power quality conditioners , 2001, 2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230).

[2]  Dushan Boroyevich,et al.  A comprehensive study of neutral-point voltage balancing problem in three-level neutral-point-clamped voltage source PWM inverters , 2000 .

[3]  H.L. Liu,et al.  Three-level space vector PWM in low index modulation region avoiding narrow pulse problem , 1993, Proceedings of IEEE Power Electronics Specialist Conference - PESC '93.

[4]  H. L. Liu,et al.  Three-level space vector PWM in low index modulation region avoiding narrow pulse problem , 1993 .

[5]  Hirofumi Akagi,et al.  A New Neutral-Point-Clamped PWM Inverter , 1981, IEEE Transactions on Industry Applications.

[6]  Jie Zhang.  High performance control of a three-level IGBT inverter fed AC drive , 1995, IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting.

[7]  Dong-Seok Hyun,et al.  A novel PWM scheme for a three-level voltage source inverter with GTO thyristors , 1994, Proceedings of 1994 IEEE Industry Applications Society Annual Meeting.

[8]  H. Akagi,et al.  Analysis of variation of neutral point potential in neutral-point-clamped voltage source PWM inverters , 1993, Conference Record of the 1993 IEEE Industry Applications Conference Twenty-Eighth IAS Annual Meeting.

[9]  T.A. Meynard,et al.  Multi-level conversion: high voltage choppers and voltage-source inverters , 1992, PESC '92 Record. 23rd Annual IEEE Power Electronics Specialists Conference.

[10]  Gyu-Hyeong Cho,et al.  DSP based space vector PWM for three-level inverter with DC-link voltage balancing , 1991, Proceedings IECON '91: 1991 International Conference on Industrial Electronics, Control and Instrumentation.