A device to-be-charged, comprising: a receiving coil comprising a first end, a second end, and a middle tap; a first charging unit coupled with the first end and the middle tap of the receiving coil and configured to convert an electromagnetic signal received at the first end and the middle tap into a first voltage and a first current for charging a battery; and a second charging unit coupled with the second end and the middle tap of the receiving coil and configured to convert an electromagnetic signal received at the second end and the middle tap into a second voltage and a second current for charging the battery; characterized in: the first charging unit comprises a first AC-DC conversion circuit; the second charging unit comprises a second AC-DC conversion circuit; the device to-be-charged further comprises: a fourth voltage conversion circuit coupled with the first AC-DC conversion circuit and the second AC-DC conversion circuit; and a fifth voltage conversion circuit coupled with the first AC-DC conversion circuit and/or the second AC-DC conversion circuit; and a first control unit is configured to control the fourth voltage conversion circuit to work in a constant-current charging stage, and control the fifth voltage conversion circuit to work in a trickle charging stage and/or a constant-voltage charging stage. a receiving coil comprising a first end, a second end, and a middle tap; a first charging unit coupled with the first end and the middle tap of the receiving coil and configured to convert an electromagnetic signal received at the first end and the middle tap into a first voltage and a first current for charging a battery; and a second charging unit coupled with the second end and the middle tap of the receiving coil and configured to convert an electromagnetic signal received at the second end and the middle tap into a second voltage and a second current for charging the battery; characterized in: the first charging unit comprises a first AC-DC conversion circuit; the second charging unit comprises a second AC-DC conversion circuit; the device to-be-charged further comprises: a fourth voltage conversion circuit coupled with the first AC-DC conversion circuit and the second AC-DC conversion circuit; and a fifth voltage conversion circuit coupled with the first AC-DC conversion circuit and/or the second AC-DC conversion circuit; and a first control unit is configured to control the fourth voltage conversion circuit to work in a constant-current charging stage, and control the fifth voltage conversion circuit to work in a trickle charging stage and/or a constant-voltage charging stage. the first charging unit comprises a first AC-DC conversion circuit; the second charging unit comprises a second AC-DC conversion circuit; the device to-be-charged further comprises: a fourth voltage conversion circuit coupled with the first AC-DC conversion circuit and the second AC-DC conversion circuit; and a fifth voltage conversion circuit coupled with the first AC-DC conversion circuit and/or the second AC-DC conversion circuit; and a fourth voltage conversion circuit coupled with the first AC-DC conversion circuit and the second AC-DC conversion circuit; and a fifth voltage conversion circuit coupled with the first AC-DC conversion circuit and/or the second AC-DC conversion circuit; and a first control unit is configured to control the fourth voltage conversion circuit to work in a constant-current charging stage, and control the fifth voltage conversion circuit to work in a trickle charging stage and/or a constant-voltage charging stage.