Modeling and analysis of PCM-controlled boost converter designed to operate in DCM

Abstract

Peak-current-mode (PCM) control has been very popular control method in power electronic converters. The small-signal modeling of the dynamics associated to the PCM control has turned out to be extremely challenging. Most of the modeling attempts have been dedicated to the converters operating in continuous conduction mode (CCM) and just a few to the converters operating in discontinuous operation mode (DCM). The DCM modeling method published in 2001 was proved recently to be very accurate when applied to a buck converter. This paper provides the small-signal models for a boost converter, and analyses first time its real dynamic behavior in DCM. The objectives of this paper are: i) To provide the full-order dynamic models for DCM-operated PCM-controlled boost converter, ii) to analyze the accuracy of the full and reduced-order dynamic models, and iii) to verify the validity of the high-frequency extension applied in the DCM-operated PCM-controlled buck converter in case of the boost converter. It is also shown that the DCM-operated boost converter can operate only in even harmonic modes similarly as all the CCM-operated PCM-controlled converters. In case of the DCM-operated PCM-controlled buck converter, the operation in the odd harmonic modes is the consequence of unstable pole in its open-loop power-stage dynamics.