A Novel Five-Level Voltage Source Inverter With Sinusoidal Pulse Width Modulator for Medium-Voltage Applications

IEEE Transactions on Power Electronics, 2015

ABSTRACT: This paper proposes a new five-level voltage source inverter for medium-voltage high-power applications. The proposed inverter is based on the upgrade of a four-level nested neutral-point clamped converter. This inverter can operate over a wide range of voltages without the need for connecting power semiconductor in series, has high-quality output voltage and fewer components compared to other classic five-level topologies. The features and operation of the proposed converter are studied and a simple sinusoidal PWM scheme is developed to control and balance the flying capacitors to their desired values. The performance of the proposed converter is evaluated by simulation and experimental results.

 KEYWORDS:

  1. Multilevel converter
  2. Dc–ac power conversion
  3. Sinusoidal pulse width modulation (SPWM)

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. New five-level three-phase inverter.

EXPECTED SIMULATION RESULTS:

Fig. 2. Simulation waveforms in steady-state condition (a) inverter voltage, (b) output currents, and (c) voltages of flying capacitors (m = 0.95).

Fig. 3. Simulation waveforms in steady-state condition (a) inverter voltage,

(b) output currents, and (c) voltages of flying capacitors (m = 0.65).

Fig. 4. Simulation waveforms in steady-state condition (inductive load) (a)

inverter voltage, (b) output currents, and (c) voltages of flying capacitors (m = 0.95, PF = 0.7).

Fig. 5. Simulation waveforms in steady-state condition (capacitive load)

(a) inverter voltage, (b) output currents, and (c) voltages of flying capacitors (m = 0.9, PF = 0.7).

Fig. 6. Simulation waveforms in transient-state condition; load changes from half-load to full-load (a) inverter voltage, (b) output currents, and (c) voltages of flying capacitors (m = 0.95).

Fig. 7. Simulation waveforms; voltage of flying capacitors with and without

the controller

CONCLUSION:

This paper introduces a new five-level voltage source inverter for medium-voltage applications. The proposed topology is the upgrade of the four-level NNPC converter that can operate over a wide range of input voltage without any power semiconductor in series. The proposed converter has fewer components as com- pared with classic multilevel converters and the voltage across the power semiconductors is only one-fourth of the dc-link. A SPWM strategy is developed to control the output voltage and regulate the voltage of the flying capacitors. The proposed strategy is very intuitive and simple to implement in a digital system. The performance of the proposed converter is confirmed by simulation in MATLAB/Simulink environment and the feasibility of the proposed converter is evaluated experimentally and results are presented.

 REFERENCES:

[1] B. Wu, High-Power Converters and AC Drives. Piscataway, NJ, USA: IEEE Press, 2006.

[2] J. Rodriguez, S. Bernet, B. Wu, J. Pontt, and S. Kouro, “Multilevel voltagesource- converter topologies for industrial medium-voltage drives,” IEEE Trans. Ind. Electron., vol. 54, no. 6, pp. 2930–2945, Dec. 2007.

[3] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B.Wu, J. Rodriguez, M. A. Perez, and J. I. Leon, “Recent advances and industrial applications of multilevel converters,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553–2580, Aug. 2010.

[4] Y. Zhang, G. Adam, T. Lim, S. Finney, andB.Williams, “Hybrid multilevel converter: Capacitor voltage balancing limits and its extension,” IEEE Trans. Ind. Informat., vol. 9, no. 4, pp. 2063–2073, Aug. 2013.

[5] M. Saeedifard, R. Iravani, and J. Pou, “Analysis and control of DCcapacitor- voltage-drift phenomenon of a passive front-end five-level converter,” IEEE Trans. Ind. Electron., vol. 54, no. 6, pp. 3255–3266, Dec. 2007.

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