Disclosed is a power inductor. The inductor comprises a magnetic core and multiple lines. The multiple lines have a first terminal and a second terminal, are parallel with each other, and wind the magnetic core to form a winding. The lines at the first terminal depart from the magnetic core at the same position, and the lines at the second terminal depart from the magnetic core at the same position. At least one line at the first terminal forms a first interface end, the other lines at the first terminal, which are not utilized to form the first interface end, form a second interface end, and the lines at the second terminal together form a third interface end. By measuring the current flowing through the first interface end using a current sensor with a small measuring range, the current flowing through the power inductor can be estimated based on ratio.