Such features as large DC voltage fluctuation and large ripple current of the support capacitor is existed when the harmonic compensation current is output by the single phase active power filter and the operation life of the capacitor and filter is affected. In this paper

the analytic relation between ripple component of DC voltage

ripple current and harmonic compensation current of capacitor is established in accordance with the equivalent circuit of filter and voltage and current transformation principle at the AC and DC side

the rule on the influence of filter’s compensation current on DC voltage fluctuation and ripple current is revealed. The correctness of theoretical analysis is verified by the simulation and test result and finally the selection suggestion on the DC support capacitor is given.