Modeling and Analysis of Circulating Current Ripples in Power-Electronics-Based Mission Profile Emulation System

Power-electronics-based mission profile emulation is becoming a popular solution to validate advanced features of power electronic converters. In order to improve the testing efficiency, the converter under test and the emulating converter are normally powered by the same power supply. Under this structure, there exists zero-sequence current path in the testing system. Thus, undesired current harmonics, instability, and extra losses may be introduced. Basically, these zero-sequence harmonics can be divided into low-order harmonics related to the fundamental frequency, and high-order ripples related to the switching frequency. The mechanisms and influences of the high-order ripples are focused on and analyzed in this paper. Sampling distortions will be induced, and thus, control errors will be triggered by certain control strategies. Simulations and experiments are provided to validate the analysis. Possible solutions to avoid the sampling distortions and control errors are also concluded and discussed.