Three-Dimensional Flux Vector Modulation of Four-Leg Sine-Wave Output Inverters

The time integral of the output voltage vector of a three-phase inverter is often termed the inverter flux vector. This paper addresses the control of a three-phase four-leg sine-wave output inverter having an LC filter at its output, by controlling the flux vector in three dimensions. Flux vector control has the property that an output filter resonance is actively damped by an output voltage control loop alone. Furthermore, an inverter switching action inherently regulates the output voltage rapidly against dc-bus voltage variations. The flux vector control of sine-wave output inverters finds several applications in three-phase four-wire systems. This paper presents a flux modulation method for three-phase four-leg inverters feeding unbalanced and nonlinear loads. All the necessary steps for the digital implementation of the flux modulator are presented. The switching behavior of the modulator has been evaluated, which is useful for the variable fundamental frequency applications of the inverters. To provide experimental validation, the modulator is implemented as a part of the control system for a stand-alone three-phase four-leg inverter with an LC filter at its output. Control system details are also provided. Experimental results indicate the effectiveness of the modulator and control system in providing balanced voltages at the output of the LC filter even under highly unbalanced conditions with nonlinear loads. The resonance damping and voltage regulation properties of the modulator are also apparent from the experimental results.

[1]  Dushan Boroyevich,et al.  Three-dimensional space vector modulation for four-leg voltage-source converters , 2002 .

[2]  H.-P. Nee,et al.  Novel flux modulated positive and negative sequence deadbeat current control of voltage source converters , 2006, 2006 IEEE Power Engineering Society General Meeting.

[3]  Poh Chiang Loh,et al.  Flux modulation for multilevel inverters , 2002 .

[4]  F. Ruppert,et al.  3-D space vector PWM for three-leg four-wire voltage source inverters , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[5]  Jiang Li,et al.  Flux vector modulation strategy for a four-switch three-phase inverter for motor drive applications , 1997, PESC97. Record 28th Annual IEEE Power Electronics Specialists Conference. Formerly Power Conditioning Specialists Conference 1970-71. Power Processing and Electronic Specialists Conference 1972.

[6]  D. Divan,et al.  Flux based active filter controller , 1995, IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting.

[7]  P. C. Loh,et al.  High-performance flux-based two-degrees-of-freedom uninterruptible power supply , 2005 .

[8]  Francisco Jurado.  Novel fuzzy flux control for fuel-cell inverters , 2005, IEEE Transactions on Industrial Electronics.

[9]  F. Blaabjerg,et al.  An integral space-vector PWM technique for DSP-controlled voltage-source inverters , 1998, Conference Record of 1998 IEEE Industry Applications Conference. Thirty-Third IAS Annual Meeting (Cat. No.98CH36242).

[10]  D. Borojevic,et al.  Analysis and comparison of space vector modulation schemes for a four-leg voltage source inverter , 1997, Proceedings of APEC 97 - Applied Power Electronics Conference.

[11]  Poh Chiang Loh,et al.  A multidimensional variable band flux modulator for four-phase-leg voltage source inverters , 2002, 2002 IEEE 33rd Annual IEEE Power Electronics Specialists Conference. Proceedings (Cat. No.02CH37289).

[12]  D.C. Patel,et al.  Control of four-leg sinewave output inverter using flux vector modulation , 2008, 2008 34th Annual Conference of IEEE Industrial Electronics.

[13]  R.R. Sawant,et al.  A Multifunctional Four-Leg Grid-Connected Compensator , 2009, IEEE Transactions on Industry Applications.

[14]  M. Morimoto,et al.  Single-chip microcomputer control of the inverter by the magnetic flux control PWM method (machine control) , 1989 .

[15]  Peter W. Lehn,et al.  Fixed-frequency space-vector-modulation control for three-phase four-leg active power filters , 2002 .

[16]  Mukul C. Chandorkar.  New techniques for inverter flux control , 2001 .

[17]  M. Morimoto,et al.  Voltage modulation factor of the magnetic flux control PWM method for inverter , 1991 .

[18]  D. Boroyevich,et al.  A three-phase inverter with a neutral leg with space vector modulation , 1997, Proceedings of APEC 97 - Applied Power Electronics Conference.

[19]  D.G. Holmes,et al.  A variable band universal flux/charge modulator for VSI and CSI modulation , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[20]  Gun-Woo Moon,et al.  A novel carrier based PWM method in three phase four wire inverters , 2004, 30th Annual Conference of IEEE Industrial Electronics Society, 2004. IECON 2004.