Analysis and modelling of circulating current in two parallel-connected inverters

Parallel-connected inverters are gaining attention for high power applications because of the limited power handling capability of the power modules. Moreover, the parallel-connected inverters may have low total harmonic distortion of the ac current if they are operated with the interleaved pulse-width modulation (PWM). However, the interleaved PWM causes a circulating current between the inverters, which in turn causes additional losses. A model describing the dynamics of the circulating current is presented in this study which shows that the circulating current depends on the common-mode voltage. Using this model, the circulating current between two parallel-connected inverters is analysed in this study. The peak and root mean square (rms) values of the normalised circulating current are calculated for different PWM methods, which makes this analysis a valuable tool to design a filter for the circulating current. The peak and rms values of the circulating current are plotted for different PWM methods, and a discontinuous PWM is identified which offers the minimum peak and rms value of the circulating current. Experimental results are presented to verify the analysis.

[1]  Rongxiang Zhao,et al.  Operation method for parallel inverter system with common dc link , 2014 .

[2]  Jung-Min Kwon,et al.  Parallel operation of photovoltaic power conditioning system modules for large-scale photovoltaic power generation , 2014 .

[3]  Jeffrey Ewanchuk,et al.  Three-limb Coupled Inductor Operation for Paralleled Multi-level Three-Phase Voltage Sourced Inverters , 2013, IEEE Transactions on Industrial Electronics.

[4]  S. M. Sharkh,et al.  Design and Control of a Grid-Connected Interleaved Inverter , 2013, IEEE Transactions on Power Electronics.

[5]  R. Ayyanar,et al.  Hybrid Interleaved Space Vector PWM for Ripple Reduction in Modular Converters , 2011, IEEE Transactions on Power Electronics.

[6]  D. Boroyevich,et al.  Common-Mode Circulating Current Control of Paralleled Interleaved Three-Phase Two-Level Voltage-Source Converters With Discontinuous Space-Vector Modulation , 2011, IEEE Transactions on Power Electronics.

[7]  S. K. Sahoo,et al.  Single-Phase Inverter Control Techniques for Interfacing Renewable Energy Sources With Microgrid—Part I: Parallel-Connected Inverter Topology With Active and Reactive Power Flow Control Along With Grid Current Shaping , 2011, IEEE Transactions on Power Electronics.

[8]  Ching-Tsai Pan,et al.  Modeling and Control of Circulating Currents for Parallel Three-Phase Boost Rectifiers With Different Load Sharing , 2008, IEEE Transactions on Industrial Electronics.

[9]  R. Ayyanar,et al.  Space Vector Based Hybrid PWM Techniques for Reduced Current Ripple , 2008, IEEE Transactions on Industrial Electronics.

[10]  Dorin O. Neacsu,et al.  A Simulation Benchmark for Selection of the PWM Algorithms for Three-Phase Interleaved Converters , 2008, IEEE Transactions on Industrial Electronics.

[11]  Frede Blaabjerg,et al.  Shunt Active-Power-Filter Topology Based on Parallel Interleaved Inverters , 2008, IEEE Transactions on Industrial Electronics.

[12]  Keyue Smedley,et al.  Parallel Operation of One-Cycle Controlled Three-Phase PFC Rectifiers , 2007, IEEE Transactions on Industrial Electronics.

[13]  Tsung-Po Chen,et al.  Common-Mode Ripple Current Estimator for Parallel Three-Phase Inverters , 2007, IEEE Transactions on Power Electronics.

[14]  Ching-Tsai Pan,et al.  Modeling and Coordinate Control of Circulating Currents in Parallel Three-Phase Boost Rectifiers , 2007, IEEE Transactions on Industrial Electronics.

[15]  T.-P. Chen,et al.  Circulating zero-sequence current control of parallel three-phase inverters , 2006 .

[16]  Thomas A. Lipo,et al.  Pulse Width Modulation for Power Converters: Principles and Practice , 2003 .

[17]  Dushan Boroyevich,et al.  Control of circulating current in two parallel three-phase boost rectifiers , 2002 .

[18]  G. Joós,et al.  A new topology of 3-phase PWM AC/DC interleaved converter for telecommunication supply systems , 2000, Conference Record of the 2000 IEEE Industry Applications Conference. Thirty-Fifth IAS Annual Meeting and World Conference on Industrial Applications of Electrical Energy (Cat. No.00CH37129).

[19]  Fred C. Lee,et al.  Interleaved PWM with discontinuous space-vector modulation , 1999 .

[20]  S. Fukuda,et al.  A control method for parallel-connected multiple inverter systems , 1998 .

[21]  V. Blasko,et al.  Analysis of a hybrid PWM based on modified space vector and triangle comparison methods , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[22]  Yun Wei Li,et al.  Investigation and Active Damping of Multiple Resonances in a Parallel-Inverter-Based Microgrid , 2013, IEEE Transactions on Power Electronics.

[23]  B. Reddy,et al.  Parallel Operation of Full Power Converters in Permanent-Magnet Direct-Drive Wind Power Generation System , 2012 .

[24]  Tsung-Po Chen,et al.  Zero-Sequence Circulating Current Reduction Method for Parallel HEPWM Inverters Between AC Bus and DC Bus , 2012, IEEE Transactions on Industrial Electronics.

[25]  B Tamyurek,et al.  A Three-Phase Unity Power Factor Single-Stage AC–DC Converter Based on an Interleaved Flyback Topology , 2011, IEEE Transactions on Power Electronics.

[26]  Ahmet M. Hava,et al.  Simple Analytical and Graphical Methods for Carrier-Based PWM-VSI Drives , 1999 .