Inductive Wireless Power Transfer Charging for Electric vehicles - A Review

Considering a future scenario in which a driverless Electric Vehicle (EV) needs an automatic charging system without human intervention. In this regard, there is a requirement for a fully automatable, fast, safe, cost-effective, and reliable charging infrastructure that provides a profitable business model and fast adoption in the electrified transportation systems. These qualities can be comprehended through wireless charging systems. Wireless Power Transfer (WPT) is a futuristic technology with the advantage of flexibility, convenience, safety, and the capability of becoming fully automated. In WPT methods resonant inductive wireless charging has to gain more attention compared to other wireless power transfer methods due to high efficiency and easy maintenance. This literature presents a review of the status of Resonant Inductive Wireless Power Transfer Charging technology also highlighting the present status and its future of the wireless EV market. First, the paper delivers a brief history throw lights on wireless charging methods, highlighting the pros and cons. Then, the paper aids a comparative review of different type’s inductive pads, rails, and compensations technologies done so far. The static and dynamic charging techniques and their characteristics are also illustrated. The role and importance of power electronics and converter types used in various applications are discussed. The batteries and their management systems as well as various problems involved in WPT are also addressed. Different trades like cyber security economic effects, health and safety, foreign object detection, and the effect and impact on the distribution grid are explored. Prospects and challenges involved in wireless charging systems are also highlighting in this work. We believe that this work could help further the research and development of WPT systems.publishedVersio

Bidirectional Electric Vehicles Service Integration in Smart Power Grid with Renewable Energy Resources

As electric vehicles (EVs) become more popular, the utility companies are forced to increase power generations in the grid. However, these EVs are capable of providing power to the grid to deliver different grid ancillary services in a concept known as vehicle-to-grid (V2G) and grid-to-vehicle (G2V), in which the EV can serve as a load or source at the same time. These services can provide more benefits when they are integrated with Photovoltaic (PV) generation. The proper modeling, design and control for the power conversion systems that provide the optimum integration among the EVs, PV generations and grid are investigated in this thesis. The coupling between the PV generation and integration bus is accomplished through a unidirectional converter. Precise dynamic and small-signal models for the grid-connected PV power system are developed and utilized to predict the system’s performance during the different operating conditions. An advanced intelligent maximum power point tracker based on fuzzy logic control is developed and designed using a mix between the analytical model and genetic algorithm optimization. The EV is connected to the integration bus through a bidirectional inductive wireless power transfer system (BIWPTS), which allows the EV to be charged and discharged wirelessly during the long-term parking, transient stops and movement. Accurate analytical and physics-based models for the BIWPTS are developed and utilized to forecast its performance, and novel practical limitations for the active and reactive power-flow during G2V and V2G operations are stated. A comparative and assessment analysis for the different compensation topologies in the symmetrical BIWPTS was performed based on analytical, simulation and experimental data. Also, a magnetic design optimization for the double-D power pad based on finite-element analysis is achieved. The nonlinearities in the BIWPTS due to the magnetic material and the high-frequency components are investigated rely on a physics-based co-simulation platform. Also, a novel two-layer predictive power-flow controller that manages the bidirectional power-flow between the EV and grid is developed, implemented and tested. In addition, the feasibility of deploying the quasi-dynamic wireless power transfer technology on the road to charge the EV during the transient stops at the traffic signals is proven

Optimization and Control of Lumped Transmitting Coil-Based In-Motion Wireless Power Transfer Systems

Wireless inductive power transfer systems are the only viable option for transferring energy to a moving vehicle. In recent years, there has been a great deal of interest in in-motion vehicle charging. The dominant technology thus far for in motion charging is elongated tracks, creating a constant eld for the moving vehicle. This technology suers from high volt ampere ratings and lower efficiency of 70%. On the other hand, stationary charging systems can demonstrate efficiency up to 95%. This thesis proposes lumped coils, similar to stationary charging coils for in-motion electric vehicle charging application. This novel primary coil architecture introduces new challenges in optimization and control. Traditional design of wireless inductive power transfer systems require designer experience, use of time consuming 3D FEM algorithms and lacks the comprehensive nature required for these systems. This thesis proposes two new optimization algorithms for the design problem which are comprehensive, based on only analytical formulations and do not need designer experience. There are challenges in the control of power transfer as well. Higher efficiency comparable to stationary systems can only be realized with proper synchronization of primary voltage with the vehicle position. Vehicle position detection and communication introduce significant cost and convenience issues. This thesis proposes a novel control algorithm which eliminates the need for vehicle position sensing and yet transfers the required percentage of energy. Both the optimization and control algorithms are verified with hardware setup

A review of compensation topologies and control techniques of bidirectional wireless power transfer systems for electric vehicle applications

Owing to the constantly rising energy demand, Internal Combustion Engine (ICE)-equipped vehicles are being replaced by Electric Vehicles (EVs). The other advantage of using EVs is that the batteries can be utilised as an energy storage device to increase the penetration of renewable energy sources. Integrating EVs with the grid is one of the recent advancements in EVs using Vehicle-to-Grid (V2G) technology. A bidirectional technique enables power transfer between the grid and the EV batteries. Moreover, the Bidirectional Wireless Power Transfer (BWPT) method can support consumers in automating the power transfer process without human intervention. However, an effective BWPT requires a proper vehicle and grid coordination with reasonable control and compensation networks. Various compensation techniques have been proposed in the literature, both on the transmitter and receiver sides. Selecting suitable compensation techniques is a critical task affecting the various design parameters. In this study, the basic compensation topologies of the Series-Series (SS), Series-Parallel (SP), Parallel-Parallel (PP), Parallel-Series (SP), and hybrid compensation topology design requirements are investigated. In addition, the typical control techniques for bidirectional converters, such as Proportional-Integral-Derivative (PID), sliding mode, fuzzy logic control, model predictive, and digital control, are discussed. In addition, different switching modulation schemes, including Pulse-Width Modulation (PWM) control, PWM + Phase Shift control, Single-Phase Shift, Dual-Phase Shift, and Triple-Phase Shift methods, are discussed. The characteristics and control strategies of each are presented, concerning the typical applications. Based on the review analysis, the low-power (Level 1/Level 2) charging applications demand a simple SS compensation topology with a PID controller and a Single-Phase Shift switching method. However, for the medium- or high-power applications (Level 3/Level 4), the dual-side LCC compensation with an advanced controller and a Dual-Side Phase-Shift switching pattern is recommended.Web of Science1520art. no. 781

Optimum Modelling Of Flux-pipe Resonant Coils For Static And Dynamic Bidirectional Wireless Power Transfer System Applicable To Electric Vehicles

Wireless power transfer (WPT) technology enables the transfer of electrical power from the electric grid to the electric vehicles across an airgap using electromagnetic fields with the help of wireless battery chargers. WPT technology addresses most problems associated with the “plug-in” method of charging EVs like vandalization, system power losses, and safety problems due to hanging cables and opened electrical contact in addition to the flexibility of charging electric vehicles while in a static or dynamic mode of operation. Significant research has been undertaken over the years in the development of efficient WPT topologies applicable to electric vehicles. A preliminary review of these revealed that the ferrite core WPT is a promising and efficient method of charging electric vehicles. The charging method is suitable for wireless charging of electric vehicles because of its low cost, high efficiency and high power output. This research proposed the use of the flux-pipe model as a suitable ferrite core, magnetic resonance coupled-based WPT system for the charging of the electric vehicle. The traditional flux-pipe model has some specific benefits which include high coupling coefficient, high misalignment tolerance and high efficiencies under misalignment conditions. However, it has a major drawback of low power output due to the generation of an equal amount of useful and non-useful fluxes. A set of governing equations guiding the performance output of a WPT system was presented. It was identified that the losses in the WPT system can be minimized by reducing the value of the maximum magnetic flux density while the power output and efficiency can be increased by increasing the value of the coupling factor and quality factor. Based on these findings, 3-D finite element modelling was employed for the optimal design and analysis of a typical flux-pipe model for higher coupling strength, high power output and low losses. The magnetic coupling performance of flux-pipe resonant coils was enhanced with an increased number of turns along the core length relative to increasing the width of each coil turns along the coil width. The high power transfer and efficiency was attained by splitting of the coil windings into two in order to reduce intrinsic coil resistances; copper sheet was employed as a shielding material in order to reduce the eddy current losses and finally, an air gap was introduced in the ferrite core in order to reduce the core losses and invariably increased the amount of excitation current required to drive the core into saturation. The proposed optimization methodology results in the creation of two models for application in static and dynamic charging operations respectively. From the simulation results presented, the model designed for static charging operations can transfer up to 11 kW of power across the airgap at a coil-to-coil efficiency of 99.12% while the model design for dynamic charging of electric vehicles can transfer up to 13 kW of power across the airgap at a coil-to-coil efficiency of 98.64% without exceeding the average limit specified for the exposure of human body to electromagnetic fields

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

Overview and Advancements in Electric Vehicle WPT Systems Architecture

Wireless Power Transfer (WPT) system is a rapidly evolving technology with vast potentials in consumer electronics, electric vehicles, biomedicals and smart grid applications such as Vehicle to Grid (V2G). Hence, this article is devoted to present an overview of recent progress in WPT with specific interest in magnetic resonance WPT and its system architectures such as compensation topologies, inputs and outputs, as well as coil structure. The strengths, drawbacks and applications of the basic compensations (SS, SP, PS, PP) and hybrid compensations (LCC and LCL) were presented and compared. Although primary parallel compensations perform well at low mutual inductance, they are rarely used due to large impedance and dependence of coefficient coupling on the load. Hence, the need for extra-compensations forming hybrid topologies, such as LCC, LCL, which usually choice topologies for dynamic WPT application or V2G application

Analysis and Design of Current-fed Wireless Inductive Power Transfer Systems

Wireless Inductive Power Transfer (IPT) technology promises a very convenient, reliable, and safe way of transferring power wirelessly. Recent research on IPT establishes its indispensable role and suitability in electric vehicle (EV) applications. Efficient design of both converters and IPT coils are essential to make this technology feasible for mass deployment. The existing research on IPT is mainly based on power converters derived from voltage-source inverter (VSI) topologies, where feasibility of current-source inverter (CSI) has received very limited attention. Considering certain limitations of voltage-fed converters, this research is focused on the concept study and feasibility analysis of current-fed power electronics for IPT systems, where the primary application is EV charging. CSI leads to parallel LC resonance in the primary side of IPT. The advantages of the parallel tank networks include lower inverter device current stress, very close to sinusoidal coil current, soft-switching of inverter devices, and natural short circuit protection during fault etc. Considering these merits, a new IPT topology is proposed in this thesis, where the inverter is full-bridge CSI and the compensations in primary and secondary sides are parallel and series types, respectively. Compared with the existing IPT topology with current-fed push-pull inverter, the proposed system does not have startup and frequency bifurcation issues. However, due to weak coupling between IPT coils, the primary side parallel capacitor experiences high voltage stress in higher power levels, and this voltage directly appears on inverter devices. To overcome this, a modified IPT topology fed from a CSI is proposed, where the primary compensation is parallel-series type and secondary compensation is series type. Detailed steady-state operation, converter design, soft-switching conditions, small-signal modelling, and closed-loop control are reported for both the topologies. To verify analytical predictions, numerical simulation is performed in PSIM 10 and experimental results obtained from a 1.6kW lab-built prototype are reported. Considering the requirement of bi-directional power flow capability to support energy injection from vehicle to grid (V2G) for future smart-grid applications, a new bidirectional IPT topology with current-fed converter is proposed. It has current-sharing feature in grid side converter and voltage doubling feature in vehicle side converter. This is the first attempt to implement bidirectional IPT with current-fed circuit and demonstrate grid to vehicle (G2V) and V2G operation. Keeping inverter output power factor lagging, ZVS turn-on of the inverter devices are always ensured irrespective of load variation. Detailed steady-state operation and converter design for both G2V and V2G modes are reported. Experimental results obtained from a 1.2kW lab-prototype are reported to verify the analysis and performances of bidirectional IPT circuit. The last part of this thesis addresses the possible improvements on reducing the number of power conversion stages to achieve higher system efficiency, compact size and reduced cost. This is usually done by using direct ac-ac converter as the primary side converter of IPT. Existing single stage IPT topologies are derived from VSI topology. From source side, these topologies have buck derived structure; therefore, none of them draw high quality current from source. In this thesis a new single stage IPT topology is proposed, which has boost derived structure and thereby capable of maintaining unity power factor at source. Dynamic load demand, source current waveshaping and effective wireless power transfer are achieved with two-loop control method. Experimental results obtained from a 1.2kW grid-connected lab-prototype are reported to justify the suitability of this single-stage IPT topology for practical use