Inductor is a device that can convert electric energy into magnetic energy and store it. The structure of the inductor is similar to that of the transformer, but there is only one winding. The inductor has a certain inductance, which only blocks the change of current. If the inductor is in the state of no current flow, it will try to block the current flow when the circuit is connected; if the inductor is in the state of current flow, it will try to maintain the current when the circuit is disconnected. Inductor is also called choke, reactor and dynamic reactor.