Design of a Variable-Frequency Inductive Charger for Low-Power
Electronic Device Applications
Abstract
The circuit design method and control strategy of a variable-frequency
inductive charger are introduced. The target application is low-power
inductive charging systems where the coupling coefficient is relatively
stable, e.g., mobile phone chargers with mechanical positioning aids. On
the transmitter side, a high-order compensation circuit is deployed to
achieve a monotonous frequency-power relation, which allows the output
power to be regulated by frequency tuning. Only a half-bridge inverter
is required and soft switching is achievable at most operating points.
On the receiver side, the load impedance is fixed around the optimal
value to improve the energy efficiency. Experimental results show that
with low-loss circuit components, the proposed scheme achieves good
efficiency performance under full and partial loads.