93738 - Technologies and Applications of Wireless Power Transfer M

Learning outcomes

The course aim is to introduce the students to the analysis and design of entire systems able to provide EM energy wirelessly. Two different approaches will be studied: the first one is based on the reactive coupling between a transmitter and a receivers by means of inductive or capacitive mechanism; the second one is based on radiative wireless power transfer and consists of active antennas at the transmitter side and rectenna (rectifying antennas) at the receiver side. Different systems will be studied depending on the power level and on the operating frequency adopted for specific applications. Specific projects will include: 1) the design of a radiative WPT system, in the UHF band, for powering energy-autonomous low- power sensors, embedded in harsh environments such as an engine compartment of a vehicle or an industrial machine; 2) the design of a WPT system for “on-the-move” wireless powering of vehicles, adopting inductive/capacitive coupling in the LF band. By means of a top-down approach, the students will learn how to evaluate a realistic power budget and how to select the proper WPT system, based on the application scenarios, to ensure the maximum system efficiency. The design of the following circuits, composing a WPT system will be studied: DC to RF converter, power generators; Wireless links radiative and reactive; RF to DC converter, rectifiers After the first analytical approach, the students will exploit CAD tools based on equivalent circuit models and on full wave EM analysis, to provide the final WPT system design. The main non-linearities responsible for energy conversion, from RF to dc and vice versa, are studied and analysed by means of harmonic balancing techniques.

Course contents

Functional blocks of radiofrequency (RF) wireless systems and main nonlinearities of their operating functions, and tools for their analysis and design.

Analytical methods for the characterization of nonlinearities in sinusoidal and multi-tone regime: frequencies generation, saturation, AM-PM conversion, frequency conversion, and nonlinear distortion.

Circuit model of nonlinear devices for power generation (transmitter side) and for RF-dc conversion (receiver side): MESFET and DIODES.

Harmonic Balance method and introduction to commercial simulation tools for RF circuit analysis/design. Hints on electromagnetic software tools. Main network functions definition for circuital performance evaluation of RF systems. In particular, the efficiency of an entire link for Wireless Power Transfer (WPT) is considered, and its different contributions are described from both a circuital and a systemistic point of view. Analyis and design of WPT subsystems both radiative (far-field) and non-radiative (near-field)

Near-field techniques

Inductive and capacitive couplings: design of the wireless link and efficiency definition

Electromagnetic modelling of coils and corresponding analysis of the performance

Scheme and design of the transmitter and the receiver

Far-field techniques

Energy harvesting from environmental sources and intentional wireless power transmission

Main characteristics of the antennas to be adopted

Possible schemes for the receiving power systems. Different rectenna (rectifying antenna) topologies

The final part of the course is devoted to the study of:

- some systems for near-field power transfer for wearable or implantable devices

- Rectennas for wide-band energy harvesting from the environment (far-field)

Readings/Bibliography

• D. Pozar, Microwave engineering, 4th Edition, Wiley

• Slide delle lezioni

• Articoli selezionati tratti dalla letteratura specializzata

• "Wireless Power Transfer - Principles and Engineering Exploration", Ki Young Kim, InTech

Teaching methods

Lectures with slides

- There will also be: i) some intermediate test activities (not subject to evaluation); ii) some laboratory classes for electromagnetic/circuit simulation training for the creation of simple models for rectennas characterization

Assessment methods

Oral exam on both theoretical and laboratory parts

Teaching tools

During the study of the theoretical part, the lecturers will continuously refer to and bring in class RF subsystems developed durign their research activity (with special emphasis on energy harvesting and WPT systems)

Office hours

See the website of Alessandra Costanzo

See the website of Mazen Al Shanawani