In power electronics applications which switching frequency is below audible frequency, the acoustic noise and vibration design of magnetics are as important as the efficiency. In the case of the powder core, which is widely used in grid-connected inverters, many researches have been progressed in terms of efficiency. However, there are only few research have been progressed related with acoustic noise and vibrations. In this paper, the Sendust(Fe-Si-Al) powder core material which has low magnetostriction and low core loss is analyzed in terms of acoustic noise and vibration induced by Maxwell force and magnetostriction. Three building structures such as, rectangular, toroidal, and oval shape are designed for 4kW grid-connected inverter, because magnetic properties and the audible noises of the inductor are varied by magnetic core building structures. The effects of the Maxwell force and magnetostriction behaviors varied with core shapes are analyzed by finite element method and experiments. In addition, experiment results of the inductor efficiency are presented according to core building structures.