Stranded litz wire is realized by twisting single wire around the stranded wire shaft with equal angular velocity and uniform forward movement of the stranded wire. Commonly used are copper and aluminum. Copper and aluminum wires can be twisted into conductors and cells of various cross-sections and different types of wires and cables. It is suitable for occasions where the operating frequency is high and the skin effect and proximity effect loss of single-strand wires are too large. The use of stranded wires can reduce the operating temperature. Compared with single-stranded wires of the same cross-sectional area, stranded wires have higher mechanical properties and flexibility.