Wireless power transfer is a method of transferring electric power from a transmitter to a receiver without requiring any physical connection between the two. Dynamic Wireless Power Transfer (DWPT) entails having the transmitters buried under the roadway and the receiver unit being installed on the Electric Vehicle (EV). In this method, EVs are charged while driving over the transmitters as they receive bursts of electric energy at the time of significant alignment between transmitters and receivers. Compared to the stationary charging method which involves parking the EV for long hours for a full charge, the dynamic charging method (i.e., DWPT) offers convenience as the vehicle gets charged while driving. It also facilitates extended driving range of EVs. Despite offering these advantages, DWPT causes a few significant issues. DWPT charging results in a transient power profile both at grid side and EV side, which not only hampers grid-side regulation but also affects EV-battery longevity. To address these two issues, both grid-side and EV-side energy management are needed to be employed to protect the grid and the vehicle from sudden exposure to harmful power transients. In this dissertation, the grid-side and EV-side energy management methods have been investigated. Firstly, a detection system to safely detect the vehicle on charging lane is proposed. This detection system is used to facilitate safe and efficient operation of DWPT chargers on EV roadways. Secondly, A novel DWPT system is proposed, which reduces the grid-side power transients with minimal additional hardware requirements. Finally, an EV-side energy management system is proposed which reduces the exposure of EV batteries to pulsating DPWT-power, thereby helping batteries to last longer.

To meet the latest requirements of the 6G standards, several techniques have been proposed in the open literature, such as millimeter waves, terahertz communication, and massive MIMO. In addition to these recent technologies, the use of unmanned aerial vehicles (UAVs) is strongly advocated for 6G networks, as the 6G standard will not be dedicated to broadband services, but will rather be oriented towards reduced geographical cellular coverage. In this context, the deployment of UAVs is considered a key solution for seamless connectivity and reliable coverage. Although UAVs are characterized by their high mobility and their ability to establish line-of-sight links, their use is still impeded by several factors such as weather conditions, their limited computing power, and, most importantly, their limited energy. In this work, we are aiming for the novel technology that enables indefinite wireless power transfer for UAVs using laser beams. We propose a novel UAV deployment strategy, based on which we analyze the overall performance of the system in terms of wireless coverage and provide some useful insights. To this end, we use tractable tools from stochastic geometry to model the complex communication system.

<p>Beam-powered aircraft are a promising solution to reducing the air transportation system's operating costs and emissions due to their reliance on typically more efficient ground-based electricity sources.</p> <p>However, modeling these aircraft is a non-trivial task due to their multi-disciplinary nature and the required interconnectedness between the aircraft, air transportation network, and power-beaming models.</p> <p><br></p> <p>This thesis establishes a methodology for holistically modeling beam-powered aircraft as a freight transportation asset in the context of their operating environment.</p> <p>This methodology accounts for elements of aircraft conceptual design, the limits of power-beaming technology, and non-idealities associated with the air transportation network.</p> <p>As a product of this methodology, this thesis also approximates beam-powered aircraft's economic and environmental feasibility based on current and future technological capabilities.</p> <p><br></p> <p>This work concludes that with an optimistic enough "engine absent" mass fraction and with sufficiently advanced technologies -- particularly with higher power density rectennas -- beam-powered aircraft are both economically and environmentally feasible, having a lower operating cost and emitting less carbon dioxide per ton-mile compared to current-day and near-future freight transportation aircraft.</p> <p><br></p> <p>More specifically, this work concludes that when using a simplified and more optimistic engine absent mass fraction model, power train specific power only needs to improve by a factor of 1.2-3.7 and rectenna power density only needs to improve by a factor of 20-30 compared to the baseline technologies considered in this work in order for beam-powered aircraft to be a feasible alternative to jet fuel powered aircraft in a freight transportation role.</p> <p>However, with a more pessimistic albeit more realistic engine absent mass fraction model, this work concludes that beam-powered aircraft are not feasible in a freight transportation role with the technology levels considered in this work.</p>

Failure of a machine can lead to production downtime and significant financial losses. Condition monitoring is implemented to avoid such downtime and devices can be used to collect data used for monitoring machine health. Vibration data is the most common type of data used for predicting machine failure. To reduce the need for hazardous cables, such devices are often battery-operated, but this can decrease monitoring device lifespans to less than 3 years, if non-rechargeable batteries are used. This thesis first proposes a design framework for implementing radio frequency energy harvesting (RFEH) at a network level. All of the necessary inputs and parameters to ensure the successful implementation of RFEH for a wireless sensor network are explored. A second design framework is then proposed for using RFEH as a source of energy to power devices for condition monitoring. This includes a power analysis of all device components, as well as the design details for an implementation of wireless power transfer using a wireless transmitter and receiver. A comparison of different types of energy sources for the device is given, followed by a case study, using commercially-available components. A simulation is used to analyze the trade-offs for different values of RFEH parameters, trading off the total cost of implementation with the system's lifetime, based on total energy consumed.

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Wireless power transfer (WPT) with loosely coupled coils is a promising solution to deliver power to a battery in a variety of applications. Due to its convenience, wireless power transfer technology has become popular in consumer electronics. Thus far, the majority of the coupled coils in these systems are planar structure, and the magnetic field induced by the transmitter coil is in one direction, meaning that the energy power transfer capability degrades greatly when there is some angle misalignment between the coupled coils. To improve the charging flexibility, a three–dimensional (3D) coils structure is proposed to transfer energy in different directions. With appropriate modulation current flowing through each transmitter coil, the magnetic field rotates in different directions and covers all the directions in 3D space. With omnidirectional magnetic field, the charging platform can provide energy transfer in any direction; therefore, the angle alignment between the transmitter coil and receiver coil is no longer needed. Compensation networks are normally used to improve the power transfer capability of a WPT system with loosely coupled coils. The resonant circuits, formed by the loosely coupled coils and external compensation inductors or capacitors, are crucial in the converter design. In WPT system, the coupling coefficient between the transmitting coil and the receiving coil is subject to the receiver's positioning. The variable coupling condition is a big challenge to the resonant topology selection. The detailed requirements of the resonant converter in an omnidirectional WPT system are identified as follows: 1). coupling independent resonant frequency; 2). load independent output voltage; 3). load independent transmitter coil current; 4). maximum efficiency power transfer; 5). soft switching of active devices. A LCCL-LC resonant converter is derived to satisfy all of the five requirements. In consumer electronics applications, Megahertz (MHz) WPT systems are used to improve the charging spatial freedom. 6.78 MHz is selected as the system operation in AirFuel standard, a wireless charging standard for commercial electronics. The zero voltage switching (ZVS) operation of the switching devices is essential in reducing the switching loss and the switching related electromagnetic interference (EMI) issue in a MHz system; therefore, a comprehensive evaluation of ZVS condition in an omnidirectional WPT system is performed. And a design methodology of the LCCL-LC converter to achieve ZVS operation is proposed. The big hurdle of the WPT technology is the safety issue related to human exposure of electromagnetic fields (EMF). A double layer shield structure, including a magnetic layer and a conductive layer, is proposed in a three dimensional charging setup to reduce the stray magnetic field level. A parametric analysis of the double shield structure is conducted to improve the attenuation capability of the shielding structure. In an omnidirectional WPT system, the energy can be transferred in any direction; however the receiving devices has its preferred field direction based on its positioning and orientation. To focus power transfer towards targeted loads, a smart detection algorithm for identifying the positioning and orientation of receiver devices based on the input power information is presented. The system efficiency is further improved by a maximum efficiency point tracking function. A novel power flow control with a load combination strategy to charge multiple loads simultaneously is explained. The charging speed of the omnidirectional WPT system is greatly improved with proposed power flow control. / Doctor of Philosophy / Wireless power transfer (WPT) is a promising solution to deliver power to a battery in a variety of applications. Due to its convenience, wireless power transfer technology with loosely coupled coils has become popular in consumer electronics. In such system, the receiving coil embedded in the receiving device picks up magnetic field induced by the transmitter coil; therefore, energy is transferred through the magnetic field and contactless charging is achieved. Thus far, the majority of the coupled coils in these systems are planar structure, and the magnetic field induced by the transmitter coil is in one direction, meaning that the energy power transfer capability degrades greatly when there is some angle misalignment between the coupled coils. To improve the charging flexibility, a three–dimensional (3D) coils structure is proposed to transfer energy in different directions, also known as in omnidirectional manner. With omnidirectional magnetic field, the charging platform can provide energy transfer in any direction; therefore, the angle alignment between the transmitter coil and receiver coil is no longer needed. In a WPT system with loosely coupled coils, the energy transfer capability suffers from weak coupling condition. To improve the power transfer capability, the electrical resonance concept between the inductor and capacitor at the power transfer frequency is adopted. A novel compensation network is proposed to form a resonant tank with the loosely coupled coils and maximize the power transfer at the operating frequency. As for the WPT system with loosely coupled coils, the energy transfer capability is also proportional to the operating frequency. Therefore, Megahertz (MHz) WPT systems are used to improve the charging spatial freedom. 6.78 MHz is selected as the system operation in AirFuel standard, a wireless charging standard for commercial electronics. The zero voltage switching (ZVS) operation of the switching devices is essential in reducing the switching loss and the switching related electromagnetic interference (EMI) issue in a MHz system; therefore, a comprehensive evaluation of ZVS condition in an omnidirectional WPT system is performed. The big hurdle of the WPT technology is the safety concern related to human exposure of electromagnetic fields (EMF). Therefore, a double layer shield structure is first applied in a three dimensional charging setup to confine the electromagnetic fields effectively. The stray field level in our charging platform is well below the safety level required by the regulation agent. Although the energy can be transferred in an omnidirectional manner in the proposed charging platform, the energy should be directed to the target loads to avoid unnecessary energy waste. Therefore, a smart detection method is proposed to detect the receiver coil's orientation and focus the energy transfer to certain direction preferred by the receiver in the setup. The energy beaming strategy greatly improves the charging speed of the charging setup.

Due to the superior characteristics compared to its silicon (Si) counterpart, the wide bandgap (WBG) semiconductor enables next-generation power electronics systems with higher efficiency and higher power density. With higher blocking voltage available, WBG devices, especially the silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET), have been widely explored in various medium-voltage (MV) applications in both industry and academia. However, due to the high di/dt and high dv/dt during the switching transient, potential overcurrent, overvoltage, and gate failure can greatly reduce the reliability of implementing SiC MOSFETs in an MV system. By utilizing the parasitic inductance between the Kelvin- and the power-source terminal, a short-circuit (SC) and overload (OL) dual-protection scheme is proposed for overcurrent protection. A full design procedure and reliability analysis are given for SC circuit design. A novel OL circuit is proposed to protect OL faults at the gate-driver level. The protection procedure can detect an SC fault within 50 nanoseconds and protect the device within 1.1 microsecond. The proposed method is a simple and effective solution for the potential overcurrent problem of the SiC MOSFET. For SiC MOSFETs in series-connection, the unbalanced voltages can result in system failure due to device breakdown or unbalanced thermal stresses. By injecting current during the turn-off transient, an active dv/dt control method is used for voltage balancing. A 6 kV phase-leg using eight 1.7 kV SiC MOSFETs in series-connection has been tested with voltage balanced accurately. Modeling of the stacked SiC MOSFET with active dv/dt control is also done to summarize the design methodology for an effective and stable system. This method provides a low-loss and compact solution for overvoltage problems when MV SiC MOSFETs are connected in series. Furthermore, a scalable auxiliary power network is proposed to prevent gate failure caused by unstable gate voltage or EMI interference. The two-stage auxiliary power network (APN) architecture includes a wireless power transfer (WPT) converter supplied by a grounded low voltage dc bus, a high step-down-ratio (HSD) converter powered from dc-link capacitors, and a battery-based mini-UPS backup power supply. The auxiliary-power-only pre-charge and discharge circuits are also designed for a 6 kV power electronics building block (PEBB). The proposed architecture provides a general solution of a scalable and reliable auxiliary power network for the SiC-MOSFET-based MV converter. For the WPT converter, a multi-objective optimization on efficiency, EMI mitigation, and high voltage insulation capability have been proposed. Specifically, a series-series-CL topology is proposed for the WPT converter. With the optimization and new topology, a 120 W, 48 V to 48 V WPT converter has been tested to be a reliable part of the auxiliary power network. For the HSD converter, a novel unidirectional voltage-balancing circuit is proposed and connected in an interleaved manner, which provides a fully modular and scalable solution. A ``linear regulator + buck" solution is proposed to be an integrated on-board auxiliary power supply. A 6 kV to 45 V, 100 W converter prototype is built and tested to be another critical part of the auxiliary power network. / Doctor of Philosophy / The wide bandgap semiconductor enables next-generation power electronics systems with higher efficiency and higher power density which will reduce the space, weight, and cost for power supply and conversion systems, especially for renewable energy. However, by pushing the system voltage level higher to medium-voltage of tens of kilovolts, although the system has higher efficiency and simpler control, the reliability drops. This dissertation, therefore, focusing on solving the possible overcurrent, overvoltage, and gate failure issues of the power electronics system that is caused by the high voltage and high electromagnetic interference environment. By utilizing the inductance of the device, a dual-protection method is proposed to prevent the overcurrent problem. The overcurrent fault can be detected within tens of nanoseconds so that the device will not be destroyed because of the huge fault current. When multiple devices are connected in series to hold higher voltage, the voltage sharing between different devices becomes another issue. The proposed modeling and control method for series-connected devices can balance the shared voltage, and make the control system stable so that no overvoltage problem will happen due to the non-evenly distributed voltages. Besides the possible overcurrent and overvoltage problems, losing control of the devices due to the unreliable auxiliary power supply is another issue. This dissertation proposed a scalable auxiliary power network with high efficiency, high immunity to electromagnetic interference, and high reliability. In this network, a wireless power transfer converter is designed to provide enough insulation and isolation capability, while a switched capacitor converter is designed to transfer voltage from several kilovolts to tens of volts. With the proposed overcurrent protection method, voltage sharing control, and reliable auxiliary power network, systems utilizing medium-voltage wide-bandgap semiconductor will have higher reliability to be implemented for different applications.

Implanted Devices are important components of the Wireless Body Area Network (WBAN) as a promising technology in biotelemetry, e-health care and hyperthermia applications. The design of WBAN faces many challenges, such as frequency band selection, channel modeling, antenna design, physical layer (PHY) protocol design, medium access control (MAC) protocol design and power source. This research focuses on the design of implanted antennas, channel modeling between implanted devices and Wireless Power Transfer (WPT) for implanted devices. An implanted antenna needs to be small while it maintains Specific Absorption Rate (SAR) and is able to cope with the detuning effect due to the electrical properties of human body tissues. Most of the proposed antennas for implanted applications are electric field antennas, which have a high near-zone electric field and, therefore, a high SAR and are sensitive to the detuning effect. This work is devoted to designing a miniaturized magnetic field antenna to overcome the above limitations. The proposed Electrically Coupled Loop Antenna (ECLA) has a low electric field in the near-zone and, therefore, has a small SAR and is less sensitive to the detuning effect. The performance of ECLA, channel model between implanted devices using Path Loss (PL) and WPT for implanted devices are studied inside different human body models using simulation software and validated using experimental work. The study is done at different frequency bands: Medical Implanted Communication Services (MICS) band, Industrial Scientific and Medical (ISM) band and 3.5 GHz band using ECLA. It was found that the proposed ECLA has a better performance compared to the previous designs of implanted antennas. Based on our study, the MICS band has the best propagation channel inside the human body model among the allowed frequency bands. The maximum PL inside the human body between an implanted antenna and a base station on the surface is about 90 dB. WPT for implanted devices has been investigated as well, and it has been shown that for a device located at 2 cm inside the human body with an antenna radius of 1 cm an efficiency of 63% can be achieved using the proposed ECLA. / Ph. D.

Wireless Power Transfer (WPT) has become quite popular over the recent years. This thesis presents some design challenges while developing a WPT system and describes a system-level methodology for designing an end-to-end system. A critical analysis of contemporary research is performed in the form of a literature survey of both academic and commercial research to understand their benefits and demerits. Some theoretical notes are presented on coupled-mode theory and coupled filter theory and the problems concerning WPT analyzed using these models. The need for higher power transfer efficiency (PTE) and power delivered to load (PDL) is studied using these models. The case for using magnetic antennas over electric antennas when surrounded by lossy media (specifically for the case of human body tissues at various frequencies) is made using some theoretical models and simulation results. An Electrically Coupled Loop Antenna (ECLA) is introduced, studied and designed for two main WPT applications, viz. free space transmission and that of powering implanted devices. An equivalent circuit is proposed to better understand the coupling effects of the antennas on a circuit level and to study the effect of various environmental and structural factors on the coupling coefficient. Some prototypes were created and measured for the two use cases of free space and implanted applications. In order to complete the system design, a negative resistance-based oscillator is designed and fabricated, that incorporates the antennas as a load and oscillates at the required frequency. Some changes in load conditions and power handling are studied by the use of two circuits for free-space (high-power) and implanted (low-power) applications. Finally, the salient points of the thesis are re-iterated and some future work outlined in the concluding chapter. / Master of Science