Use of Transmitter-Side Electrical Information to Estimate System Parameters of Wireless Inductive Links

The power transfer efficiency and power transfer characteristics of wireless inductive links are determined by several intrinsic and extrinsic factors, such as coupling coefficient, quality factors, matching conditions of the transmitting and receiving coils, and operating frequency. The nominal component values, such as the capacitors used in matching the coils, are chosen by considering the optimal power transfer efficiency and power transfer requirement at the nominal operating condition. However, due to manufacturing tolerance, temperature effect, and aging, electronic components are subject to parameter variations. Such unavoidable issue would cause performance degradation of the link. Typically, it is tackled by conducting on-the-spot measurements of the electrical quantities together with sophisticated communication links and protocols to provide the transmitter with the operating condition of the receiver. To reduce system complexity, this paper presents another perspective by processing transmitter-side electrical information with an evolutionary computation technique to estimate several system parameters, including coil inductances and quality factors, resonant frequencies of the transmitting and receiving networks, and coupling coefficient, for the transmitter to manage power transfer. The proposed technique has been applied to a 4-W wireless-powered LED driver prototype for regulating the load power under parametric variations.