| 摘要 |
A near field inductive power transfer system 10, comprises a transmitter 100 to transmit power wirelessly at a transmission frequency fO to a power reception device 200 that is moveable relative to it and, when in a near field region, receives power for a variable load 230. Power reception device 200 comprises a receiver circuit 210 having a resonant frequency fR. A ratio of the transmitter frequency and receiver resonant frequencies fO/fR is between 0.2 and 3. An impedance emulator 220 provides power to the load and suppresses variation in the impedance presented to the receiver circuit by the varying load. The impedance emulator can comprise a DC-DC converter such as a zeta, flyback, buck-boost, SEPIC, Cuk, buck or boost converter that draws a substantially constant power. Power transmitted by transmission device 100 can be controlled in dependence upon a feedback signal indicating an output voltage of the receiver circuit, measured by voltage monitor 240 and transmitted by signal transmitter 250 to feedback receiver 130. |
