Wireless power transfer is widely used in implantable medical devices to eliminate the use of battery. Due to load and coupling variations, the received DC voltage at the output of the rectifier in the implant is not steady. Conventionally, a global control loop is built based on a feedback through a data link. The quick global loop response could help improving the stability of the received voltage. But it requires high data rate of the data link, which would bring in some overhead such as low power transfer efficiency in the case that power link and data link share the same pair of coils or system design complexity in the case that power link and data link use separated pair of coils. To reduce the implant size, one pair of coils shared by both power link and data line is preferred, w...[ Read more ]

Wireless power transfer is widely used in implantable medical devices to eliminate the use of battery. Due to load and coupling variations, the received DC voltage at the output of the rectifier in the implant is not steady. Conventionally, a global control loop is built based on a feedback through a data link. The quick global loop response could help improving the stability of the received voltage. But it requires high data rate of the data link, which would bring in some overhead such as low power transfer efficiency in the case that power link and data link share the same pair of coils or system design complexity in the case that power link and data link use separated pair of coils. To reduce the implant size, one pair of coils shared by both power link and data line is preferred, which is applied in this thesis. To solve the conflicts between the high power transfer efficiency and the high data rate, two solutions are presented.

The first solution is based on the feed-forward control, which is applied in an adaptive wireless powering and data telemetry system for optic nerve stimulation. Trade-off is made between the power transfer efficiency, the size of the implant and the data link bandwidth. The feed-forward control is used to improve the load transient without the need of the high data rate. To balance the external system’s power conversion efficiency and high data bandwidth, an external power supply solution for the power amplifier is also given.

The second solution is based on a 1X/2X reconfigurable rectifier. First, the inductive powering analysis with the 1X/2X reconfigurable rectifiers together is given to provide theoretical guidelines for the wireless power transfer system design using the 1X/2X reconfigurable rectifier. Then, a 13.56MHz wireless power transfer system with reconfigurable resonant regulating rectifier and wireless power control for IMDs is presented. Finally, to improve the workable coupling- and load-range of the system, a primary equalizer is presented.