The invention provides a composite coil which comprises a DD coil, a solenoid coil and a
magnetic core, the DD coil is a bipolar coil, two sub-coils of the DD coil are equal in size and opposite in winding direction, and a generated
magnetic field is distributed along a coil axis, the
magnetic core is arranged below the DD coil, the solenoid coil is wound on the DD coil in parallel, the solenoid coil is a multi-turn rectangular winding, and the solenoid coil and the
magnetic core form a solenoid structure. The invention further provides a double-channel
wireless power supply
system constant current output method based on the coil. Through matching the impedance value of a load, the self-
inductance of a transmitting solenoid coil, the
resonance inductance of a receiving end, the mutual
inductance between a transmitting DD coil and a receiving DD coil, which changes along with the offset in the X direction, and the mutual inductance between a transmitting solenoid coil and the receivingDD coil, which changes along with the offset in the X direction, when the transmitting coil and the receiving coil deviate, the current passing through the load is still kept constant. According to the invention, the defect that the current is seriously reduced under the condition that the transmitting coil and the receiving coil of a traditional WPT
system deviate is overcome, the material
utilization rate of the resonant
inductor is improved, and the space occupied by the transmitting coil is saved.