22.3 Adaptive reconfigurable voltage/current-mode power management with self-regulation for extended-range inductive power transmission

摘要

Wireless power transmission (WPT) via inductive coupling is used in many applications such as biomedical implants, sensors, and radio-frequency identification (RFID). Range extension, robustness against load (RL) variations and coil misalignments and rotations, and miniaturization of inductive links are key in such applications, demanding new architectures for the integrated power management (IPM) [1–6]. Conventional IPMs in the form of rectifiers or doublers operate in voltage mode (VM) using active synchronous switches to achieve high AC-DC power-conversion efficiency (PCE) in [1–3]. However, they suffer from limited voltage-conversion efficiency (VCE), requiring large AC carriers across the receiver (RX) LC-tank. In [4], the RX LC-tank has been shorted twice in every power carrier cycle for RL modulation. Although this approach increases PTE for small RL, it is not suitable for large RL and VCE is still less than 1. A resonant current-mode (CM) IPM has recently been presented in [5], primarily used for recharging battery-powered implants with sub-volt AC carriers. However, it requires a battery for startup and is not suitable for direct WPT. For applications that involve large coupling distance (d) and RL variations, neither VM- nor CM-only IPMs achieve highest power transmission efficiency (PTE), because VM and CM are suitable for small and large d or RL, respectively [6].