Extension of operation of space vector PWM strategies with low switching frequencies using different overmodulation algorithms

This paper investigates the operation of four space vector-based synchronized pulse-width modulation (PWM) strategies in the overmodulation zone using three different overmodulation algorithms. It is shown that the symmetries in the PWM waveforms generated can be preserved in the overmodulation zone also. With any given overmodulation algorithm, the voltage control characteristics (i.e., fundamental voltage versus control variable) are found to vary with PWM strategy, pulse number and type of clamping. The inverse of the appropriate voltage control curve is used during premodulation to maintain the modulator gain constant. The differences in the nature of the voltage control characteristics with the different overmodulation algorithms are brought out. These characteristics are compared and contrasted against those at high switching frequencies. The harmonic distortion in the different cases is evaluated and compared. It is shown that the bus clamping strategies perform better than the conventional strategy with any given overmodulation algorithm employed. These strategies, which exploit the flexibilities in the space vector approach, are useful in high power drives on account of their superior waveform quality at low switching frequencies and high DC bus utilization.

[1]  Joachim Holtz,et al.  On continuous control of PWM inverters in the overmodulation range including the six-step mode , 1992, Proceedings of the 1992 International Conference on Industrial Electronics, Control, Instrumentation, and Automation.

[2]  J. Holtz,et al.  Pulsewidth modulation for electronic power conversion , 1994, Proc. IEEE.

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

[4]  Bong-Hwan Kwon,et al.  An effective software implementation of the space-vector modulation , 1999, IEEE Trans. Ind. Electron..

[5]  G Narayanan,et al.  Synchronised Pulsewidth Modulation Strategies Based On Space Vector Approach For Induction Motor Drives , 1999 .

[6]  Silverio Bolognani,et al.  Novel digital continuous control of SVM inverters in the overmodulation range , 1997 .

[7]  Ahmet M. Hava,et al.  Carrier-based PWM-VSI overmodulation strategies: analysis, comparison, and design , 1998 .

[8]  H. Stemmler.  High-power industrial drives , 1994 .

[9]  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.

[10]  Dong-Choon Lee,et al.  A novel overmodulation technique for space vector PWM inverters , 1997, PESC97. Record 28th Annual IEEE Power Electronics Specialists Conference. Formerly Power Conditioning Specialists Conference 1970-71. Power Processing and Electronic Specialists Conference 1972.

[11]  V. Kaura.  A new method to linearize any triangle comparison based PWM by reshaping the modulation command , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[12]  John T. Boys,et al.  Practical real-time PWM modulators: an assessment , 1992 .

[13]  V. T. Ranganathan,et al.  Synchronised PWM strategies based on space vector approach. Part 2: Performance assessment and application to V/f drives , 1999 .

[14]  G. Joos,et al.  Incorporating the overmodulation range in space vector pattern generators using a classification alg , 1997 .

[15]  D. G. Holmes.  The significance of zero space vector placement for carrier based PWM schemes , 1995, IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting.

[16]  V. Ranganathan,et al.  Synchronised PWM strategies based on space vector approach. Part 1 : Principles of waveform generation , 1999 .

[17]  Seung-Ki Sul,et al.  Unified voltage modulation technique for real time three-phase power conversion , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[18]  Joachim Holtz,et al.  On continuous control of PWM inverters in the overmodulation range including the six-step mode , 1993 .