Analysis of the Load Interactions in Constant-Current-Controlled Buck Converter

The paper investigates the load interactions in constant-current-controlled buck converters. The nominal transfer functions and the load interaction formalism are derived from the voltage-output-converter model by applying duality. It is observed that the constant-current control makes the converter very sensitive to load interactions implying that a proper controller design is a necessity. The high crossover frequency in the nominal control-to-output transfer function may lead to performance degradation if the initial control design is done with resistive load, because the typical load for constant-current controlled converters is a low impedance storage-battery recovering the nominal feature. It is shown that electronic loads, typically used in prototype testing and verification, might have unexpected characteristics. This may lead to wrong deductions of the converter stability and performance

[1]  Seungwon Choi,et al.  Designing control loop for DC-to-DC converters loaded with unknown AC dynamics , 2002, IEEE Trans. Ind. Electron..

[2]  T. Suntio,et al.  Characterization of Regulated Converters to Ensure Stability and Performance in Distributed Power Supply Systems , 2005, INTELEC 05 - Twenty-Seventh International Telecommunications Conference.

[3]  Slobodan Cuk,et al.  A general unified approach to modelling switching-converter power stages , 1976, 1970 IEEE Power Electronics Specialists Conference.

[4]  Robert Tenno,et al.  Battery impedance and its relationship to battery characteristics , 2002, 24th Annual International Telecommunications Energy Conference.

[5]  V. J. Thottuvelil.  Modeling and analysis of power converter systems with batteries , 1997, Proceedings of Power and Energy Systems in Converging Markets.

[6]  Teuvo Suntio.  Unified average and small-signal modeling of direct-on-time control , 2006, IEEE Transactions on Industrial Electronics.

[7]  K. Zenger,et al.  Practical design issues of multi-loop controller for a telecom rectifier , 2000, TELESCON 2000. Third International Telecommunications Energy Special Conference (IEEE Cat. No.00EX424).

[8]  B. Lehman,et al.  Performance prediction of DC-DC converters with impedances as loads , 2004, IEEE Transactions on Power Electronics.

[9]  Koosuke Harada,et al.  The overload-protection characteristics of the current-mode DC-to-DC converter: analysis and improvement , 1988, PESC '88 Record., 19th Annual IEEE Power Electronics Specialists Conference.

[10]  T. Suntio,et al.  Load-Impedance Based Interactions in Regulated Converters , 2005, INTELEC 05 - Twenty-Seventh International Telecommunications Conference.

[11]  T. Suntio,et al.  Constant-current vs. constant-power protected rectifier as a DC UPS system's building block , 1996, Proceedings of Intelec'96 - International Telecommunications Energy Conference.

[12]  Slobodan Cuk,et al.  A general unified approach to modelling switching-converter power stages , 1977 .