Design criteria for parallel connected-buck converters in DC microgrid loaded by CPLs

Power electronic converters and electric motor drives in advanced automotive systems, when they are tightly regulated, behave as constant power loads (CPLs) at the input terminals and usually cause negative impedance instability problems. Especially in a DC microgrid system with multiple parallel-connected buck converters, which is loaded by CPLs, the improper parameter settings of the buck converters may trigger oscillation and collapse. This paper analyzes the relationships of the parameters in a mathematical angle and proposes a design criteria to place the design constraints on the buck converters to prevent instabilities. Simulation results based on MATLAB/Simulink verify that the proposed criteria could insure the system's stability.