Low-frequency voltage ripples in the flying capacitors of the nested neutral-point-clamped converter

The flying capacitors (FCs) of the nested neutral-point-clamped (NNPC) converter show an inherent voltage ripple at fundamental frequency. This ripple can be significantly large under some operating conditions of the converter. In this paper, the amplitudes of the low-frequency voltage ripples in the FCs are determined. An averaged model of the NNPC converter is introduced and used in the analysis. The amplitudes of the capacitor voltage ripples are provided using normalized variables so that this information can be used to size the FCs of the converter in different applications. The results of the analysis are validated experimentally in a laboratory prototype.

[1]  Rainer Marquardt,et al.  An innovative modular multilevel converter topology suitable for a wide power range , 2003, 2003 IEEE Bologna Power Tech Conference Proceedings,.

[2]  Stephen J. Finney,et al.  Distributed Control of a Fault-Tolerant Modular Multilevel Inverter for Direct-Drive Wind Turbine Grid Interfacing , 2013, IEEE Transactions on Industrial Electronics.

[3]  Bin Wu,et al.  A Novel Five-Level Voltage Source Inverter With Sinusoidal Pulse Width Modulator for Medium-Voltage Applications , 2016, IEEE Transactions on Power Electronics.

[4]  Fang Zheng Peng,et al.  A multilevel voltage-source inverter with separate DC sources for static VAr generation , 1995, IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting.

[5]  Bin Wu,et al.  A Novel and Simple Single-Phase Modulator for the Nested Neutral-Point Clamped (NNPC) Converter , 2015, IEEE Transactions on Power Electronics.

[6]  Gonzalo Abad,et al.  Modular Multilevel Converter With Different Submodule Concepts—Part II: Experimental Validation and Comparison for HVDC Application , 2013, IEEE Transactions on Industrial Electronics.

[7]  Bhatkar Anup Ashok,et al.  A solar power generation system with a seven-level inverter , 2018 .

[8]  Bin Wu,et al.  Recent Advances and Industrial Applications of Multilevel Converters , 2010, IEEE Transactions on Industrial Electronics.

[9]  Dushan Boroyevich,et al.  Voltage-balance limits in four-level diode-clamped converters with passive front ends , 2005, IEEE Transactions on Industrial Electronics.

[10]  Bin Wu,et al.  A New Power Conversion System for Megawatt PMSG Wind Turbines Using Four-Level Converters and a Simple Control Scheme Based on Two-Step Model Predictive Strategy—Part I: Modeling and Theoretical Analysis , 2014, IEEE Journal of Emerging and Selected Topics in Power Electronics.

[11]  Thierry Meynard,et al.  Multicell converters: derived topologies , 2002, IEEE Trans. Ind. Electron..

[12]  Giampaolo Buticchi,et al.  A Nine-Level Grid-Connected Converter Topology for Single-Phase Transformerless PV Systems , 2014, IEEE Transactions on Industrial Electronics.

[13]  Thierry Meynard,et al.  Stacked multicell converter (SMC): properties and design , 2001, 2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230).

[14]  Christopher D. Townsend,et al.  Impact of Practical Issues on the Harmonic Performance of Phase-Shifted Modulation Strategies for a Cascaded H-Bridge StatCom , 2014, IEEE Transactions on Industrial Electronics.

[15]  Bin Wu,et al.  A New Power Conversion System for Megawatt PMSG Wind Turbines Using Four-Level Converters and a Simple Control Scheme Based on Two-Step Model Predictive Strategy—Part II: Simulation and Experimental Analysis , 2014, IEEE Journal of Emerging and Selected Topics in Power Electronics.

[16]  Dushan Boroyevich,et al.  New feedforward space-vector PWM method to obtain balanced AC output voltages in a three-level neutral-point-clamped converter , 2002, IEEE Trans. Ind. Electron..

[17]  Bin Wu,et al.  A New Nested Neutral Point-Clamped (NNPC) Converter for Medium-Voltage (MV) Power Conversion , 2014, IEEE Transactions on Power Electronics.

[18]  Vassilios G. Agelidis,et al.  Voltage Balancing Method for a Flying Capacitor Multilevel Converter Using Phase Disposition PWM , 2014, IEEE Transactions on Industrial Electronics.

[19]  Marta Molinas,et al.  An Energy-Based Controller for HVDC Modular Multilevel Converter in Decoupled Double Synchronous Reference Frame for Voltage Oscillation Reduction , 2013, IEEE Transactions on Industrial Electronics.

[20]  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.

[21]  Bin Wu,et al.  Model Predictive Decoupled Active and Reactive Power Control for High-Power Grid-Connected Four-Level Diode-Clamped Inverters , 2014, IEEE Transactions on Industrial Electronics.

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