Hybrid Modulation Concept for Five-Level Active-Neutral-Point-Clamped Converter

ABSTRACT:  

In this letter, a hybrid modulation concept consisting of three-level space vector modulation (3L-SVM) and phase-shifted pulse width modulation (PS-PWM) is proposed for five-level active neutral- point-clamped (5L-ANPC) converter. Under this concept, a simpler 3L-SVM plus PS-PWM scheme is applied to realize 5L modulation, instead of using complex 5L-SVM. The control of neutral voltage, flying capacitor voltage, and the improved dc voltage utilization are all implemented. With the help of the proposed concept,   well-developed 3L-SVM schemes can be directly applied to the 5L-ANPC converter, which significantly simplify the gating signal generation. This concept can also be applied to other hybrid clamped 5L converters with two dc-link capacitors. It provides a unique solution, which utilize lower level SVM scheme to control higher level multilevel converters.

KEYWORDS:

  1. Five-level active-neutral-point-clamped (5LANPC)
  2. Multilevel converter
  3. Phase-shifted pulse width modulation (PS-PWM)
  4. Space vector modulation (SVM)

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 

Fig. 1 Single-phase circuit of a 5L-ANPC converter.

 EXPECTED SIMULATION RESULTS:

 

Fig. 2. Waveforms of modulation wave Vma , phase voltage vphase , line–line voltage vl l , three-phase current, two dc-link capacitor voltage, and three-phase FC voltage of 5L-ANPC converter with proposed hybrid modulation concept: (a) M = 0.23. (b) M = 1.15. (c) Neutral voltage and FC voltage control.

 

Fig. 3. Comparison waveforms of modulation wave Vma , phase voltage vphase , line–line voltage vl l , three-phase current, two dc-link capacitor voltage, and three-phase FC voltage of 5L-ANPC converter with PS-PWM in [5]: (a) M = 0.23. (b) M = 1.15. (c) Neutral voltage and FC voltage control.

 CONCLUSION:

 In this letter, a new hybrid modulation concept is proposed for 5L-ANPC converters. Instead of using 5L-SVM, it applies 3L-SVM plus PS-PWM to modulate the 5L-ANPC converters. With the proposed concept, the control of neutral voltage, FC voltage, and the increased voltage utilization are all realized.  Well-developed 3L-SVM schemes can be applied directly to simplify the modulation process. The simulation and experiment have proved the effectiveness of the modulation scheme. Although this modulation concept is developed for 5L-ANPC converter, it can also be applied to other hybrid 5L converters with two dc-link capacitors [13]. By dividing these converters into two cells, 3L-SWM can be applied to their 3L converter cells, while both cells are together modulated by PS-PWM using the modulation waves derived from 3L-SVM. The proposed concept provides a unique solution which utilize lower level SVM scheme to modulation higher level multilevel converters at desired performance.

REFERENCES:

[1] S. Kouro, J. Rodriguez, B. Wu, S. Bernet, and M. Perez, “Powering the future of industry: High-power adjustable speed drive topologies,” IEEE Ind. Appl. Mag., vol. 18, no. 4, pp. 26–39, Jul./Aug. 2012.

[2] P. Barbosa, P. Steimer, J. Steinke, M. Winkelnkemper, and N. Celanovic, “Active-neutral-point-clamped (ANPC) multilevel converter technology,” in Proc. Power Electron. Appl. Eur. Conf., 2005, pp. 1–10.

[3] J. Li, Z. Pan, and R. Burgos, “A new control scheme of five-level active NPC converters for common mode voltage mitigation in medium voltage drives,” in Proc. IEEE Energy Convers. Congr. Expo., 2014, pp. 234–241.

[4] R. T. Hamid, S. Danny, M. M. Kashem, and C. Phil, “Novel modulation  and control strategy for five-level ANPC converter with unbalanced DC voltage applied to a single-phase grid connected PV system,” in Proc.  IEEE Ind. Appl. Soc. Annu. Meet., 2013, pp. 1–8.

[5] K. Wang, L. Xu, Z. Zheng, and Y. Li, “Capacitor voltage balancing of a five-level ANPC converter using phase-shifted PWM,” IEEE Trans. Power  Electron., vol. 30, no. 3, pp. 1147–1156, Mar. 2015.

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