Practical Characterization of Input-Parallel-Connected Converters with a Common Input Filter

1. Practical Characterization of Input-Parallel-Connected Converters with a Common Input Filter S. Vesti Practical characterization of the described system based on four measured transfer functions is presented. Special transfer functions, obtained computationally, are utilized for detailed interactions analysis and experimental results are provided to support the presented analysis procedure. Introduction Project sponsored by • Input-parallel-connected converters • Stability and transient performance analysis • Commercial components • Available information is limited • Due to the external impedances within the system: • Interactions within the system • Instability / performance degradation might occur Modeling Method • Internal converter dynamics • Linear system representation • Source- and load- affected system description • Four transfer functions • Special parameters for interactions analysis • Two-port representation • Obtained computationally from measurements • Dynamic system-level model • Short-circuit input admittance • Open-circuit output impedance • Information on the converter sensitivity to interactions Practical Characterization Experimental Results • Frequency response measurements • Without input filter • Cross-coupling mechanism exists due to common input filter • Input impedances • Source-affected output impedance: Zin • Load step at PMB influences on the DSP output voltage ZS Zin-sco • With input filter • Converter sensitivity analysis: • Output impedances • Stability • Performance Altered Zo Original Zo CONCLUSIONS • Various interactions mechanisms exist within a system • Method to analyze converter and system sensitivity to the external impedances was introduced • Analysis is based on special transfer functions, that are computed from the measurements