A new control technique to enhance the stability of a DC microgrid and to reduce battery current ripple during the charging of plug-in electric vehicles

The charging of batteries acting as constant power loads from a DC microgrid leads to oscillations in the main bus voltage beyond certain power levels and hence makes the system unstable. A control technique is proposed to generate the reference current for a battery charger such that it enhances the power absorbed from the grid without creating instability. The technique also mitigates the charging current ripple when the current shifts from one reference to the other. Small signal approximation was done to obtain a linearized system model. The eigen values of the system matrix were analyzed to examine stability.