Maximum Power Transfer versus Efficiency in Mid-Range Wireless Power Transfer Systems

• Main Authors: Paulo J. Abatti, Sérgio F. Pichorim, Caio M. de Miranda
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Microondas e Optoeletrônica; Sociedade Brasileira de Eletromagnetismo
• Series: Journal of Microwaves, Optoelectronics and Electromagnetic Applications
• Subjects: Maximum power transfer; power transfer efficiency; relative power transfer; wireless power transfer
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2179-10742015000100097&lng=en&tlng=en

AbstractThe condition for maximum power transfer of 2-coils wireless power transfer (WPT) system is derived from circuit analysis and discussed together with the respective WPT system efficiency (η). In the sequence, it is shown that a 4-coils WPT system (which can be divided in source, two communication and load circuits) without power losses at the two communication circuits (ideal 4-coils WPT system) presents, from maximum power transfer and efficiency point of view, a performance similar to those of a 2-coils WPT system. The exception is the influence of coupling coefficient (k): in 2-coils system η increases as k approaches one, while in ideal 4-coils WPT system η increases as k between the two communication coils approaches zero. In addition, realistic 4-coils WPT systems (with power losses at the two communication circuits) are also analyzed showing, for instance, that η presents a maximum as a function of k of the communication coils. In order to validate the presented theory, 4 coils were built, and a setup to perform 2-coils and 4-coils WPT systems has been carried out. Practical results show good agreement with the developed theory.