Inductive Power Transmission Systems

Abstract

Abstract Powering up and recharging a variety of mobile devices, such as implantable medical devices (IMD), smartphones, and electric vehicles, are governed by the same fundamental principles of near‐field inductive coupling, which guide the design constraints and practical considerations of inductive power transmission described in this article. The coupling coefficient and power transmission efficiency (PTE) of an inductive link, which are affected by important geometrical and circuit design parameters on both transmitter (Tx) and receiver (Rx) sides, are discussed. The inductive link PTE has been modeled based on the reflected load theory, indicating that the mutual coupling between the coils has the most significant effect on the PTE, followed by the primary and secondary coils' quality factors. To these factors, one should add the load resistance, source resistance, carrier frequency, and the surrounding environment. Three and four‐coil inductive links have been utilized as a way to achieve optimal loading condition and to reduce the negative effect of load/source resistances on the PTE. This article also includes an optimization method for the wireless links that are made of printed spiral coils (PSC), which are suitable for IMDs and radio‐frequency identification (RFID) applications.