| 摘要 |
An inductive power transfer system 1 transfers power from the coil 12 of a primary unit 10 to one or more proximate secondary devices 30 electromagnetically, without electrical contact. The system stops supplying power when it detects a substantial difference between the power being drawn and the power required by the secondary device(s) 30 to prevent heating of a foreign object which may be close to the primary coil 12. The power drawn maybe measured in the primary unit 10 when secondary device 30 is set to a no load state and power may be switched off when the measured power is greater than a threshold or when the power is less than a standby value. The power requirement of secondary device 30 may be transmitted to primary unit 10 using an RFID method, or by varying the load it imposes and such communications may include an identity, allowing primary unit 10 to use stored information, and a synchronising signal. Primary unit 10 may compensate for losses and for parasitic loads. The system may be used to charge batteries in portable electric devices such as mobile phones (fig 4, 501). |
