A Design Method to Minimize Detuning for Double Sided LCC Compensated IPT System Improving Efficiency Versus Air Gap Variation

Inductive power transfer (IPT) technology has garnered considerable attention due to its widespread range of applications. The variation in the air gap can result in variations in the loosely coupled transformer (LCT) parameters, including self-inductance and mutual inductance, due to positional deviations with the ferrite cores on both sides. These variable LCT parameters can damage the resonant tank, ultimately resulting in reduced efficiency. To address this problem, a double-sided LCC-compensated IPT system with a compact decoupled coil is proposed in this paper to improve the system's efficiency with respect to the air gap variation. The key idea is to neutralize the variation in LCT parameters through the use of the self-inductance variation of the decoupled coil so that the detuning degree of the system can be suppressed. Subsequently, the analysis and parametric design process of the system are elaborated. Finally, a 1 kW experimental setup is built to verify the feasibility of the proposed method. Experimental results show that the efficiency of the system proposed in this work varies from 92.63% to 74.81%, as the air gap increases from 30mm to 90mm, wherein the primary and secondary self-inductance and mutual inductance increased by 19.3% and 135.3%, respectively. Compared with the traditional method, the maximum efficiency improvement is up to 8.16%

Optimization of 8-Plate Multi-Resonant Coupling Structure Using Class-E\u3csup\u3e2\u3c/sup\u3e Based Capacitive-Wireless Power Transfer System

Capacitive-wireless power transfer (CPT) effectively charges battery-powered devices without a physical contact. It is an alternative to inductive-wireless power transfer (IPT) which is available in the present market. Compared with IPT, CPT offers flexibility in designing the coupling section. Because of its flexibility, CPT utilizes various coupling methods to enhance the coupling capacitance. Misalignment is a common issue in any WPT system. Among IPT and CPT, IPT has better performance for misalignments, but it requires bulk and expensive ferrite core to attain a high coupling coefficient. This work focuses on designing a CPT system to minimize the impact of misalignments. In this research, a novel 8-plate multi-resonant Class-E2 CPT system is developed to improve the performance of the CPT system for misalignments. The proposed CPT model expands the resonant frequency band, which results in better performance for misalignments compared with the regular 4-plate CPT system. The 8-plate coupling structure is designed to charge a 100 Ah drone battery. For this application, the coupling is formed when the drone lands on the capacitive- wireless charging pad. This work also presents the analysis of several dielectric materials with different dielectric constants. A well-designed capacitive coupler can effectively limit harmonics during the interaction between transmitter and receiver. Also, the effect of coupling plate shape is identified on the CPT system. The hardware tests indicate the round-shaped plates have better stability in coupling capacitance with the variation in frequency. The effect of misalignments is studied through the impedance tracking of the Class-E2 power converter. Impedance plots for 50 μH, and 100 μH resonant inductors are used to determine input current peak for each case. Additionally, hardware tests are performed to study the variation of input current and output voltage for a range of frequencies. The test results indicate the efficiency at optimal impedance point for a resonant inductor with 50 μH is 8% higher compared to the CPT with a 100 μH resonant inductor which highlights the effects of the resonant inductor on efficiency. The zero-voltage-switching (ZVS) limits are also identified for varying frequencies and duty cycles. Later in this research, the optimal design of the Class-E rectifier is identified to enhance the power transfer. Several cases were considered to investigate the impact of the secondary inductor on the output voltage and the ZVS property. Hardware tests validate that under optimal conditions the efficiency of the Class-E2 based CPT system improves by 18% compared with Ar \u3e\u3c 1. Further work presents the advantages of 8-plate multi-resonant coupling for misalignments. The proposed model has a simple design procedure which enhances the power flow from the inverter to the rectifier section. The hardware results of the proposed 8-plate multi-resonant coupling show an increase in efficiency to 88.5% for the 20.8 W test, which is 18% higher than regular 4-plate coupling. Because of the wider resonant frequency band [455- 485 kHz], compared with regular 4-plate coupling, the proposed design minimized the output voltage drop by 15% for 10% misalignment. Even for large misalignments, 8-plate improves the CPT performance by 40% compared with 4-plate coupling

Improved Design of Wireless Electrical Energy Transfer System for Various Power Applications

This thesis introduces a state-of-the-art review of existing wireless power transfer (WPT) technologies with a detailed comparison and presents the limitations of the inductive power transfer system through simulation and practical analyses. This thesis also presents the expanded use of the high-frequency analysis tool, known as FEKO, and the novel application of frequency response analyser (FRA) with various simulations and practical demonstrations for enhancing the design and maintenance of WPT systems

Underwater Inductive Power Transfer with Wireless Charging Applications

Underwater wireless power transfer (UWPT) has become an area of great interest due to the advancement of autonomous underwater vehicles (AUVs) and electic boats. This paper seeks to investigate the variation of the coupling coefficient and power transfer in air versus in seawater. The design is based on a class E converter as it can achieve soft-switching inherently. I made the transmitter and receiver coils then measured self-inductance and parasitic resistance in air and in water. I noted that self-inductance increases when they are placed in water but the mutual inductance is lower. I then calculated the component values for the class E converter based on inductor values (140 μH and 105 μH) and simulated the circuit on LTspice. The power at the output was 74W which is lower than the required value. However, I noted that reducing the coils inductance values while maintaining the value of the other passive components increased the efficiency and power at the output upto four times (311W). The final value chosen for making the inductors was 115 μH and 75 μH as these values gave the maximum power at the output while achieving ZVS. I then designed the transmitter and receiver circuits on Altium and printed the PCBs. All the components were then soldered onto the board and the tests done

A High Frequency Wireless Power Transfer System for Electric Vehicle Charging Using Multi-layer Non-uniform Self-resonant Coil

Wireless EV (Electric Vehicle) charging is an emerging technology with rapid development in the past decade. Compared to wired EV chargers, wireless power transfer (WPT) enables safe and unobtrusive charging for EVs. This work proposes high frequency wireless charging using a self-resonant (SR) coil at several megahertz. A multi-layer self-resonant coil structure is proposed, allowing high quality factor coils to be fabricated from layers of inexpensive copper foil and dielectric film. Additionally, the self-resonant coil utilizes its interlayer capacitance for resonance, eliminating the external compensation capacitor and shrinking the overall volume of passive component to increase the power density. Comparing to other self-resonant coils in the literature, it exhibits the characteristics of achieving high quality factor and high inductance simultaneously. Prototype coils with 200 mm radius are fabricated and tested, achieving quality factor over 450 at 3 MHz. The fabricated air-core coil structure is low-cost and lightweight, with 200 mm radius, 3 mm thickness and only 2 oz copper traces. The power stages, including GaN (Gallium Nitride) transistor based inverter and SiC (Silicon Carbide) diode based rectifier, are designed with emphasis on reduction of PCB (Printed Circuit Board) layout parasitics. Experimental tests show 95.2% dc-dc efficiency with 6.6 kW power transferred across a 100 mm coil-to-coil distance. The power density is 52.5 kW/m2, without need for any external compensation components. This work validates the concept of high frequency compact WPT system for EV. Practical shielding design is proposed for the WPT system with self-resonant coils, considering the high frequency parallel resonance effect. Complete coil pads are fabricated and assembled, incorporating the ferrite cores, PTFE (Polytetrafluoroethylene) spacer, and aluminum plate. The system is validated with shielded SR coils, achieving 92.3% DC-DC efficiency and 7.1 kW/dm3 volumetric power density. This work demonstrates the first 6.6-kW WPT system using compact self-resonant coils with practical shielding implementation. The concept of proposed multi-layer self-resonant coil is extended to other possible structures. Different multi-layer self-resonant coil structures are compared and analyzed, giving design guidelines for their capabilities at different system operating frequencies

Emerging Works on Wireless Inductive Power Transfer: AUV Charging from Constant Current Distribution and Analysis of Controls in EV Dynamic Charging

Wireless power transfer through inductive coupling, termed as inductive power transfer (IPT), is one of the important technologies in power electronics that enable transfer of power between entities without physical connections. While it has seen significant growth in the areas such as electric vehicle charging, phone charging and biomedical implants, its emerging applications include charging of autonomous underwater vehicles (AUVs) and dynamic charging of electric vehicles from the roadway. This dissertation addresses a few key challenges in these areas of IPT applications, paving the way for future developments. For the WPT for AUV, the recently developing sea-bed installed marine systems are targeted, which typically gets power from on-shore sources through constant dc low-current distribution. As the present underwater IPT topologies are not suitable for such applications, this dissertation proposes underwater IPT topologies to interface directly with such constant current distribution and provide a constant voltage output supply to the on-board systems inside the AUVs. The considerations for seawater losses and the small-signal models for control purposes are also addressed. Analysis and experimental results are provided for validations of the analytical designs and models. In the area of electric vehicle dynamic wireless power transfer (EV DWPT), the comparison of control performances of different coupler, compensation topologies and control implementations are addressed. The effect of communication latency on control bandwidth are also addressed. The outcomes are presented through analysis and simulations, and based on that future research recommendations are made to pave way for future commercial developments of well regulated and interoperable EV DWPT systems

Design and performance evaluation of different power pad topologies for electric vehicles wireless charging systems

Range limitations and charging of electric vehicles (EVs) are major concerns in the modern electrified transportation systems. In this thesis, design and performance analysis of three power pads considered for EV’s wireless charging systems are carried out. In particular, a comparative performance analysis is conducted for circular and double D (DD) power pads, and a new power pad named DDC power pad is designed by combining these two power pads. Wireless charging systems of EV’s are developed, mainly based on the inductive power transfer (IPT) system where the power is transferred through electromagnetic induction. A systematic approach to power pad design is presented in detail and the Society of Automotive Engineers (SAE) recommended practice J2954 is followed for designing the physical dimension of these power pads. To this end, Finite Element Analysis (FEA) tool ANSYS Maxwell 3D is used for simulation. Extensive simulation studies are carried out to verify the efficiency of the proposed DDC power pad. It is found that the proposed DDC power pad offers significantly improved performance compared to the existing circular and DD power pads under various misaligned positions

Miniaturised Wireless Power Transfer Systems for Neurostimulation: A Review

In neurostimulation, wireless power transfer is an efficient technology to overcome several limitations affecting medical devices currently used in clinical practice. Several methods were developed over the years for wireless power transfer. In this review article, we report and discuss the three most relevant methodologies for extremely miniaturised implantable neurostimulator: ultrasound coupling, inductive coupling and capacitive coupling. For each powering method, the discussion starts describing the physical working principle. In particular, we focus on the challenges given by the miniaturisation of the implanted integrated circuits and the related ad-hoc solutions for wireless power transfer. Then, we present recent developments and progresses in wireless power transfer for biomedical applications. Last, we compare each technique based on key performance indicators to highlight the most relevant and innovative solutions suitable for neurostimulation, with the gaze turned towards miniaturisation

Modelling and Investigation of Wireless Power Transfer for Small Gap Applications

Wireless Power Transfer (WPT) is a process of transferring power to any load without using wires. WPT technology has help public in term of their devices portability and conveniences. There are two types of wireless power transfer which are Inductive Power Transfer (IPT) and Capacitive Power Transfer (CPT). This project investigate IPT for small gap applications, focusing on coil parameters in affecting efficiency of WPT. Coils with different number of turns is implemented to determine the maximum power and distances in power transfer

Challenges of Inductive Electric Vehicle Charging Systems in both Stationary and Dynamic Modes

Inductive power transfer as an emerging technology has become applicable in wide power ranges including Electric Vehicle, Electric Aircraft, wheelchair, cellphone, scooter and so on. Among them, inductive Electric Vehicle (EV) charging has gained great interest in the last decade due to many merits namely contactless technology, more convenience, full automotive charging process. However, inductive EV charging systems could bring about so many issues and concerns which are addressed in this dissertation. One of the critical challenges addressed in this dissertation is a virtual inertia based IPT controller to prevent the undesirable dynamics imposed by the EVs increasing number in the grid. Another adverse issue solved in this dissertation is detecting any metal object intrusions into the charging zone to the Inductive Power Transfer (IPT) systems before leading to heat generation on the metal or risk of fire. Moreover, in this dissertation, a new self-controlled multi-power level IPT controller is developed that enables EV charging level regulation in a wide range of power; suitable for different applications from golf-cart charging system (light duty EV) to truck (heavy duty EV). The proposed controller has many merits including easy to be implemented, cons-effective, and the least complexities compared to conventional PWM methods. Additionally, in this dissertation, the online estimation of IPT parameters using primary measurement including coupling factor, battery current and battery voltage is introduced; the developed method can find immediate applications for the development of adaptive controllers for static and dynamic inductive charging systems. Finally, the last objective of this research is physics-based design optimization techniques for the magnetic structures of inductive EV charging systems for dynamic application (getting charged while in motion). New configuration of IPT transmitting couplers with objective of high-power density, low power loss, low cost and less electromagnetic emission are designed and developed in the lab