Transformer, power module and switching power supply

The utility model provides a transformer, a power module and a switching power supply. The transformer comprises a magnetic core, a primary winding and a secondary winding, the magnetic core comprises a first cover plate, a second cover plate, a wrapping post and at least two side posts; the first cover plate and the second cover plate are respectively connected with the top surfaces and the bottom surfaces of the wrapping post and the at least two side posts of the magnetic core; at least one side column is provided with a through channel, the primary winding is wound on the winding column, and a lead of the primary winding penetrates out of the through channel; and a lead of the secondary winding penetrates out of a gap formed by the at least two side columns. According to the utility model, the lead of the primary winding can pass through the through channel, thereby saving space and improving the power density of the switching power supply. 本实用新型提供了一种变压器、功率模块及开关电源，所述变压器包括磁芯、原边绕组和副边绕组；所述磁芯包括第一盖板、第二盖板、绕线柱和至