A high frequency battery model for current ripple analysis

In applications where batteries work together with power electronic circuits, the current ripple generated by the power electronics will be shared by both the battery and passive components in the circuit. The amount of ripple absorbed by the battery depends on its impedance at the switching frequency of power electronics. This paper presents an impedance based high frequency battery model derived from test results of a NiMH battery using a novel battery impedance tester. The possible reasons for the battery impedance characteristics in high frequency region, including skin effect and proximity effect, are also discussed. This battery model can be directly used in current ripple analysis, passive components design and control strategy optimization of power electronic circuits. The effect of the passive component values on the battery current ripple is analyzed using the ac equivalent circuit of the test setup.