Planar transformer, power conversion circuit, and adapter

A planar transformer, comprising a magnetic core and a printed circuit board (PCB) winding board, wherein the PCB winding board comprises:

• a primary winding, wherein a first terminal of the primary winding is connected to an electric potential quiescent point of a primary circuit of a power conversion circuit, and a first turn of coil of the primary winding is disposed at a start position of the first terminal of the primary winding;
• a secondary winding, wherein a first terminal of the secondary winding is connected to an electric potential quiescent point of a secondary circuit of the power conversion circuit, and a first turn of coil of the secondary winding is disposed at a start position of the first terminal of the secondary winding;
• a shielding winding, disposed between the primary winding and the secondary winding, and configured to shield electric field coupling between the primary winding and the secondary winding;
• and
• a compensation winding, adjacent to the primary winding or adjacent to the secondary winding, wherein the compensation winding comprises N turns of coils, and N is a positive number greater than 1
• wherein the compensation winding is adjacent to a first winding layer in a first winding:
• the first winding is the primary winding adjacent to the compensation winding or the secondary winding adjacent to the compensation winding;
• and an (Ns)th turn to an (Ns+B−1)th turn of coils of the first winding are disposed at the first winding laver, wherein N satisfies the following condition:
• N=Nb×C, and Nb=2×Ns+B−2, wherein
• an induced voltage generated by Nb turns of coils is equal to an induced voltage generated by the first winding, C is a real number greater than 0, and Nb, Ns, and B are positive numbers.