Robust Beamforming Design for Magnetic MIMO Wireless Power Transfer Systems
Yixin Zhang, Da Chen, Tao Jiang
Abstract
In this paper, we investigate the robust beam-forming for the magnetic-based wireless power transfer (WPT) with multiple transmitters and multiple receivers to improve the power efficiency and reliability. By taking into account the imperfection of the magnetic mutual inductances information (MII), we firstly formulate a beam-forming optimization problem to minimize the total transmit power while guaranteeing the reliable power delivery for each receiver simultaneously. Then, observing that the optimization problem is highly non-convex with infinite number of constraints, we utilize the norm-bounded MII error models to reformulate the original problem into two worst-case optimization problems for the cases of the single receiver and multiple receivers, respectively. Finally, the optimal beam-forming is obtained for the case of single receiver by applying the semi-definite programming relaxation (SDR) and the approximately optimal solution is obtained for the case of multiple receivers by adopting the SDR and randomization. Extensive simulation results verify the power transfer reliability and efficiency of the proposed beam-forming schemes for the magnetic-based WPT systems.