Wireless Charger for Pacemakers Controlled from Primary Current Without Communication with Secondary Side

This paper discusses the implementation of a wireless inductive power transfer system for pacemaker applications. One of the inherent challenges in these systems is regulating the output voltage, as there is no direct physical connection from the primary. Additionally, there are other challenges, such as variability in magnetic coupling. First, resonant converters for inductive charging topologies are investigated for biomedical applications. Then, a control method based on the system’s modeling is proposed, eliminating the need for communication. This method is designed for systems with variable and unknown coupling and specifically for a resonant series–parallel topology. For an operation point, determined by the coupling factor, the primary current is measured to regulate the output voltage by adjusting the input voltage. The relationship between the input current and the input voltage is set by a look-up table. The effectiveness of this control strategy is validated in the PSIM simulator and with experimental results for a coupling range between 0.3 and 0.5, achieving a regulated output current error of less than 1%, and an output voltage range within the limits of the battery charger.