Start-Up Process and Step Response of a DC–DC Converter Loaded by Constant Power Loads

Constant power loads (CPLs) are very common in multiconverter power system applications. Buck converters loaded by CPLs have different start-up and step-response processes from the resistive load. This paper analyzes the start-up process and step response of an average current-controlled buck converter with CPLs based on the phase portrait method. Design criteria rules have been proposed to achieve system stability during start-up and load transient processes. The proper current-limiting value is proposed accordingly to avoid the instability during the start-up and load change dynamics. Simulation and experimental results verify the analysis and the proposed proper current-limit value.