A Comparison of Time-Domain Implementation Methods for Fractional-Order Battery Impedance Models

This paper is a comparative study of the multiple RC, Oustaloup and Grünwald–Letnikov approaches for time domain implementations of fractional-order battery models. The comparisons are made in terms of accuracy, computational burden and suitability for the identification of impedance parameters from time-domain measurements. The study was performed in a simulation framework and focused on a set of ZARC elements, representing the middle frequency range of Li-ion batteries’ impedance. It was found that the multiple RC approach offers the best accuracy–complexity compromise, making it the most interesting approach for real-time battery simulation applications. As for applications requiring the identification of impedance parameters, the Oustaloup approach offers the best compromise between the goodness of the obtained frequency response and the accuracy–complexity requirements.

Analog Realization of Fractional-Order Capacitor and Inductor via the Caputo–Fabrizio Derivative

Capacitors and inductors have been proven to exhibit fractional-order characteristics. Therefore, the establishment of fractional-order models for circuits containing such components is of great significance in practical circuit analysis. This study establishes the impedance models of fractional-order capacitors and inductors based on the Caputo–Fabrizio derivative and performs the analog realization of fractional-order electronic components. The mathematical models of fractional RC, RL, and RLC electrical circuits are deduced and verified via a comparison between the numerical simulation and the corresponding circuit simulation. The electrical characteristics of the fractional circuits are analyzed. This study not only enriches the models of fractional capacitors and inductors, but can also be applied to the description of circuit characteristics to obtain more accurate results.

Powering electronic implants by high frequency volume conduction: in human validation

Aiming at miniaturization, wireless power transfer (WPT) is frequently used in biomedical electronic implants as an alternative to batteries. However, WPT methods in use still require integrating bulky parts within the receiver, thus hindering the development of devices implantable by minimally invasive procedures, particularly when powers above 1 mW are required in deep locations. In this regard, WPT based on volume conduction of high frequency currents is an advantageous alternative relatively unexplored, and never demonstrated in humans. We describe an experimental study in which ac and dc electric powers in the order of milliwatts are obtained from pairs of needle electrodes (diameter = 0.4 mm, separation = 30 mm) inserted into the arms or lower legs of five healthy participants while innocuous and imperceptible high frequency (6.78 MHz) currents are delivered through two textile electrodes strapped around the considered limb. In addition, we demonstrate a procedure to model WPT based on volume conduction which characterizes coupling between the transmitters and the receivers by means of two-port impedance models which are generated from participants' medical images.