High-Efficiency Multiuser Wireless Power Transfer by Sequentially Tracking the Optimal Rectified Power of Multiple Groups With a Power-Limited Transmitter

In a practical wireless power transfer (WPT) system with multiple nonlinear receivers and a power-limited transmitter, rectification efficiency may be low because the received radio frequency (RF) power of the receiver does not match the optimal rectified power. To tackle the challenge that a power-limited transmitter actively transmits RF power to satisfy different power demands with high efficiency and large average output direct current (dc) power, this article proposes a novel high-efficiency multiuser WPT. In this scheme, the transmission signals are optimized based on the received RF signals with power equal to the optimal rectified power from the selected receivers, so the selected receivers can track the optimal rectified power within a time slot. Then, we formulate a bilevel optimization problem under the constraint of transmit power to group all receivers and optimize the transmission signals of each group. Multiple groups sequentially track the optimal rectified power across multiple time slots with a power-limited transmitter, thereby tackling the challenge. In order to solve the nonconvex bilevel optimization problem, a bilevel genetic algorithm is adopted to obtain the optimal solution. Numerical and experimental results show that the RF-RF-dc efficiency and output dc power of the proposed scheme are up to 2.6 and 3.7 times higher than those of the traditional schemes. Additionally, only our scheme meets the different power demands of multiple receivers, ensuring the same survival time. Furthermore, our scheme can also provide guidance for practical WPT system design and has the potential of compatibility with other existing systems.