Interleaved Operation of Three-Level Neutral Point Clamped Converter Legs and Reduction of Circulating Currents Under SHE-PWM

Interleaving of voltage-source converter (VSC) legs enables higher output currents per phase, effectively increasing the power rating without increasing semiconductor ratings. However, the interleaved operation results in circulating currents between each phase converter legs as well as a zero-sequence circulating current (ZSCC), which become quite prominent when the converters operate with low switching frequencies. This paper demonstrates the interleaved operation of three-level converters under selective harmonic elimination pulsewidth modulation (SHE-PWM). A controller for the circulating current within the legs of each phase is also proposed. The controller is used in combination with optimally selected SHE-PWM patterns to generate the maximum number of voltage levels and minimize the peak value of the circulating current. Simulation and experimental results show the interleaved operation and the effect of SHE-PWM pattern selection in the overall system.

[1]  Gerry Moschopoulos,et al.  Improved Method for Paralleling Reduced Switch VSI Modules: Harmonic Content and Circulating Current , 2014, IEEE Transactions on Power Electronics.

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

[3]  T. Kawabata,et al.  Parallel Operation of Voltage Source Inverters , 1986, 1986 Annual Meeting Industry Applications Society.

[4]  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.

[5]  Yijie Zhou,et al.  Zero-Sequence Current Suppression Strategy of Open-Winding PMSG System With Common DC Bus Based on Zero Vector Redistribution , 2015, IEEE Transactions on Industrial Electronics.

[6]  Robert Stala.  A Natural DC-Link Voltage Balancing of Diode-Clamped Inverters in Parallel Systems , 2013, IEEE Transactions on Industrial Electronics.

[7]  Ivo Barbi,et al.  A Control Strategy for Parallel Operation of Single-Phase Voltage Source Inverters: Analysis, Design and Experimental Results , 2013, IEEE Transactions on Industrial Electronics.

[8]  V. Agelidis,et al.  Theoretical Considerations for Single-Phase Interleaved Converters Operated With SHE-PWM , 2014, IEEE Transactions on Power Electronics.

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

[10]  Yu Zhang,et al.  The zero-sequence circulating currents between parallel three-phase inverters with three-pole transformers and reactors , 2006, Twenty-First Annual IEEE Applied Power Electronics Conference and Exposition, 2006. APEC '06..

[11]  Vassilios G. Agelidis,et al.  Harmonic elimination control of a five-level DC-AC cascaded H-bridge hybrid inverter , 2010, The 2nd International Symposium on Power Electronics for Distributed Generation Systems.

[12]  Georgios Konstantinou,et al.  Control strategy to balance operation of parallel connected legs of modular multilevel converters , 2013, 2013 IEEE International Symposium on Industrial Electronics.

[13]  Gerry Moschopoulos,et al.  Three-Phase Multimodule VSIs Using SHE-PWM to Reduce Zero-Sequence Circulating Current , 2014, IEEE Transactions on Industrial Electronics.

[14]  Georgios Konstantinou,et al.  A Review of Multilevel Selective Harmonic Elimination PWM: Formulations, Solving Algorithms, Implementation and Applications , 2015, IEEE Transactions on Power Electronics.

[15]  Vassilios G. Agelidis,et al.  Current-Balancing Technique for Interleaved Voltage Source Inverters With Magnetically Coupled Legs Connected in Parallel , 2015, IEEE Transactions on Industrial Electronics.

[16]  Hung-Chi Chen,et al.  Simplified PWM With Switching Constraint Method to Prevent Circulating Currents for Paralleled Bidirectional AC/DC Converters in Grid-Tied System Using Graphic Analysis , 2015, IEEE Transactions on Industrial Electronics.

[17]  Ashwin M. Khambadkone,et al.  Reliability Analysis and Cost Optimization of Parallel-Inverter System , 2012, IEEE Transactions on Industrial Electronics.

[18]  Georgios Konstantinou,et al.  Enhanced Phase-Shifted PWM Carrier Disposition for Interleaved Voltage-Source Inverters , 2015, IEEE Transactions on Power Electronics.

[19]  Yan Liu,et al.  A high-performance 2×27 MVA machine test bench based on multilevel IGCT converters , 2014, 2014 IEEE Energy Conversion Congress and Exposition (ECCE).

[20]  Georgios Konstantinou,et al.  Reducing circulating currents in interleaved converter legs under selective harmonic elimination pulse-width modulation , 2015, 2015 IEEE International Conference on Industrial Technology (ICIT).

[21]  Baoming Ge,et al.  Multiphase-Leg Coupling Current Balancer for Parallel Operation of Multiple MW Power Modules , 2014, IEEE Transactions on Industrial Electronics.

[22]  G. Moschopoulos,et al.  Three-phase multi-module VSIs using SHE-PWM with reduced zero-sequence circulating current , 2012, 2012 IEEE Energy Conversion Congress and Exposition (ECCE).

[23]  Keiju Matsui,et al.  Parallel-connected five-level PWM inverters , 2003 .