用于扩展WPT工作距离的再生式自供电关断电路及串并联配置

One of the challenges in simultaneously designing long range wireless power transfer (WPT) for multiple devices is that the induced voltages of the receivers vary according to their proximity and the load conditions of each of the devices. This article presents an adaptive series/parallel configuration method for a multidevice wireless charging system to maintain the voltages of the receivers. The proposed series-mode/parallel-mode configuration scheme comprises a regenerative self-powered cut-off circuit (RSCC) and an auxiliary coil, which enhances both power transfer performance and the safe-operation region of the receiver. The proposed method employs the RSCC that avoids the use of bulky isolated gate drivers and snubber circuits for bidirectional switches (BDSs). The RSCC can also be used for a simple over-voltage protection (OVP) circuit for relatively small devices, such as wearable devices where additional coils for the adaptive series/parallel configuration are not affordable due to the size limitation. The smartphone with the adaptive series/parallel configuration resulted in an extended operation distance range of 5–25 cm and increased the load power up to 8.7 W with 49% efficiency at D=9 cm, while the traditional method achieved a maximum load power of 1.8 W with 7% efficiency. The OVP circuit of the wearable device was verified over 5 D 15 cm with a constant power load of 1.5 W. Additionally, the proposed receiver maintained power transfer performance under lateral misalignment, achieving 12 W at 67% efficiency. In a multidevice scenario, two receivers simultaneously received a combined power of 13.5 W at 65% efficiency.