Multi Objective Decision Making for Improving the Stability and Efficiency of a Multi-converter System Loaded with Constant Power Load

Abstract

Multi-converter power electronics system is used in mobile application. There are many DC/DC, DC/AC and AC/DC converters used to provide different voltage levels. Due to tightly regulated nature of load, these converters behave like Constant Power Load (CPL) in a multi-converter system, with a main converter supplying these loads. A CPL has a negative impedance characteristic which results in a destabilizing effect on the main converter driving them. A Constant Voltage Load (CVL) in parallel with CPL and parasitic components added in the converter improve the stability of converter. The parasitic elements when inserted in the circuit will certainly improve the stability of the system but reduce its efficiency. In order to achieve a given stability limit a tradeoff has to be made with the efficiency of the system. This paper presents improvement in the stability of converter due to parasitic elements and CVL and their effect on efficiency of the system. Both CVL and parasitic elements improve the stability at the cost of efficiency. Therefore, it is essential to find an optimum value of the parasitic element which improves the stability of the system with least compromise in efficiency.