||Tue 2010-Feb-02 12:41:41
||Wed 2012-Feb-01 16:02:12
||The simplicity and low cost of capacitive interfaces
makes them very attractive for wireless charging stations. Major
benefits include low electromagnetic radiation and the amenability
of combined power and data transfer over the same interface.
We present a capacitive power transfer circuit using series
resonance that enables efficient high frequency, moderate voltage
operation through soft-switching. An included analysis predicts
fundamental limitations on the maximum achievable efficiency
for a given amount of coupling capacitance and is used to find
the optimum circuit component values and operating point. Automatic
tuning loops ensure the circuit operates at the optimum
frequency and maximum efficiency over a wide range of coupling
capacitance and load conditions.
An example interface achieves near 80% efficiency at 3.7W
with only 63 pF of coupling capacitance. An automatic tuning
loop adjusts the frequency from 2 to 8 MHz to allow for a wide range of alignment conditions. On-
off modulation is used to maintain efficiency at light loads.
|IAB Research Area
||Mitchell H. Kline, Igor I. Izyumin
||Bernhard E. Boser, Seth Sanders