Wireless charging systems are foreseen as an effective solution to improve the convenience and safety of conventional conductive chargers. As this technology has matured, recent broad applications of wireless chargers to electrified transportation have indicated a trend toward higher power, power density, modularity, and scalability of designs. In this article, commercial systems and laboratory prototypes are reviewed, focusing mostly on the advances in high-power wireless charging systems. The recent endeavors in magnetic pad designs, compensation networks, power electronics converters, control strategies, and communication protocols are illustrated. Both stationary and dynamic (in-motion) wireless charging systems are discussed, and critical differences in their designs and applications are emphasized. On that basis, the comparisons among different solutions and design considerations are summarized to present the essential elements and technology roadmap that will be necessary to support large-scale deployment of high-power wireless charging systems. The review is concluded with the discussion of several fundamental challenges and prospects of high-power wireless power transfer (WPT) systems. Foreseen challenges include utilization of advanced materials, electric and electromagnetic field measurement and mitigation, customization, communications, power metering, and cybersecurity.

Advances in High-Power Wireless Charging Systems: Overview and Design Considerations

To acquire high efficiency and reduce electromagnetic interference in wireless high-power charging for electric vehicles (EVs), it is of great importance to realize accurate zero voltage switching angle (ZVSA) control of the inverter. However, the traditional zero-crossing detection cannot be applied in high power because of considerable noise and poor accuracy in wide power range applications. In this paper, to suppress the noise in high power, a current hysteresis comparator is adopted, and an enhanced phase detection methodology is proposed to measure the phase of resonant current by using a reference signal produced by a processor. Meanwhile, to improve the accuracy of ZVSA, a uniform time delay compensation method (UTDCM) by considering the whole time delays synthetically is proposed, and a uniform time delay equation can be obtained to guarantee the high accuracy of phase detection, especially in the wide power range. Finally, a novel control strategy with the ZVSA loop based on UTDCM is proposed for battery charging in wireless high-power transfer system. A 500-W wireless power transfer prototype is built to verify the accuracy of ZVSA based on UTDCM and the system efficiency can achieve 94.17% with $k$ = 0.22.

Analysis, Design, and Implementation of Accurate ZVS Angle Control for EV Battery Charging in Wireless High-Power Transfer

Sliding mode control (SMC) has been a very popular control technology due to its simplicity and robustness against uncertainties and disturbances since its inception more than 60 years ago. Its very foundation of stability and stabilization is built on the principle of the Lyapunov theory which ascertains asymptotic stability. In the 1990s, a novel class of SMC, called the terminal sliding mode control (TSMC), was proposed which has been studied and applied extensively, giving rise to a robust control with tunable finite-time convergence delivering fast response, high precision, and strong robustness. In recent years, interest in this particular control technology has been increasing. This paper provides an overview of the state of the art of the TSMC theory and its applications, and postulates key technical issues and future challenges.

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Terminal Sliding Mode Control – An Overview

Recently, electric vehicles (EVs) are becoming increasingly popular, as they decrease reliance on fossil fuels and reduce greenhouse gas emissions. However, there are still many challenges hindering the adoption of EVs. For example, EVs have short driving ranges and long charging times. To overcome these challenges, wireless power transfer (WPT) is emerging as a promising solution. WPT enables the efficient wireless charging of EVs to increase driving range, while simultaneously decreasing battery size and improving convenience. This paper presents a comprehensive overview of recent trends in WPT technologies and applications to wireless charging of EVs. The fundamental principles of WPT are briefly explained. The state-of-the-art technical progress in the field of WPT is explored in detail. The latest applications of WPT to charging EVs are thoroughly investigated, including stationary and dynamic wireless charging. Moreover, the economic feasibility of stationary and dynamic wireless charging of EVs is analyzed. Finally, to address safety issues related to human exposure to electromagnetic fields (EMFs), methods for EMF shielding are proposed.

A review of recent trends in wireless power transfer technology and its applications in electric vehicle wireless charging

Electric vehicle (EV) dynamical wireless charging is an emerging application area of wireless power transfer technologies. Compared with a classical static charging mode, there are two key challenges in a dynamical charging process. One is to determine charging area and corresponding excitation unit. The other is to provide large energy in a short time interval. Based on multiexcitation unit configuration for EV dynamical charging, this paper proposes a charging area determining method. The dynamical mutual inductance can be calculated based on dc current input and load detection. A charging area can be figured out based on output power requirement. And a switching mode method is given to control the charging process for multiexcitation unit configuration. On this basis, a power and efficiency enhancement method is proposed by utilizing a multiexcitation unit in the charging area. This method is beneficial for improving system power capacity without increasing the voltage and current stress. Finally, experimental results show that this method can realize accurate charging area determining and control. And the output power of dual excitation unit configuration can increase almost four times than that of a traditional single excitation unit configuration.

Charging Area Determining and Power Enhancement Method for Multiexcitation Unit Configuration of Wirelessly Dynamic Charging EV System

Due to the strong nonlinearity, coupling characteristics, external disturbance, and complex driving conditions, it is difficult to establish an accurate mathematical model for the autonomous ground vehicle (AGV). This requires the AGV path following controller to have strong robustness. In this paper, a robust AGV path following control strategy that is based on nonsingular terminal sliding mode (NTSM) and active disturbance rejection control (ADRC) is presented. First, the complex path following problem is simplified to a simple yaw angle tracking problem by constructing a desired yaw angle function that satisfies that the displacement deviation of AGV converges to zero when the actual yaw angle approaches the desired yaw angle. Second, an NTSM-ADRC controller is designed for the system, which uses the extended state observer to estimate and compensate the unmodeled dynamics and unknown external perturbations of the system in real time. In order to improve response characteristics of the controller, the nonlinear error feedback control law is designed by combining the NTSM and exponential approximation law. In contrast to the existing work, the improved controller can use the simple two-degree-of-freedom linear vehicle dynamic model to provide good performance in a range of driving conditions. Finally, the CarSim–Simulink simulation results of typical conditions show that the proposed control strategy can make the AGV follow the reference path quickly and accurately while ensuring the stability of the vehicle and has strong robustness.

Path Following Control of Autonomous Ground Vehicle Based on Nonsingular Terminal Sliding Mode and Active Disturbance Rejection Control

The invention relates to an intelligent home system which comprises a server and intelligent home terminals having a browser function, wherein the server at least comprises an intelligent home WEB server, on which various home Web services are integrated; the intelligent home WEB server is externally connected to an internet, for realizing various remote control of a user; the intelligent home WEB server is internally connected to each of the intelligent home terminals through a local area network; the intelligent home terminals are connected to at least one control terminal in wired or wireless manner, for finishing information transformation between the server and the control terminal and sending transformed information to the intelligent home WEB server or the control terminal; the control terminal, as an actuator of the intelligent home system, is directly connected to various domestic appliances, for directly controlling the domestic appliances; the intelligent home terminals are provided with fixed IP (Internet Protocol) addresses; and the control terminal connected to the intelligent home terminals is used for uniformly addressing

Intelligent home system

This paper presents an equivalent model to analyze switch-on process of dynamic wireless charging system of electric vehicle (EV). In the model, system initial state before switching is considered and the full response is used to describe the switch-on process. First, the system states before and after switching are discussed, and an approximate method is proposed to calculate the initial value of converter dc-side voltage in switch-on unit. Then, equivalent transient sources and system transfer functions are obtained to establish the switch-on model. So, the switch-on process can be described through full responses of the selected currents under the excitation of equivalent sources. Furthermore, the proposed model is verified by a developed dynamic wireless EV charging prototype. Also, switch-on transient characteristics are investigated through discussions on system parameter and vehicle speed effects. Finally, a simple way to select the suitable switching position is provided based on the analysis of switching position influence, and its effectiveness has been validated by experimental results.

Switch-On Modeling and Analysis of Dynamic Wireless Charging System Used for Electric Vehicles

Disclosed is an intelligent power grid management system. In a certain area, an area-level minisize intelligent power grid system is established, which uses the common power supply of regenerative resources such as photovoltaic generation and wind power generation and the traditional power grid as the main power supply, the micro-turbine generation as the supplementary power supply, and the storage battery energy storage as the adjusting device; and comprehensively connects the power supply system with the distribution system of the area, the power utilization system of each building user. And then the intelligent power grid system including a generation and energy storage side management system as well as a power utilization side management system is comprehensively managed by utilizing the network communication and the intelligent control as the nerve centre, thus effectively lifting the utilization rate of regenerative resources in the area, raising the reliability of the power supply network of the area, improving the intellectualization degree of the whole power grid of the area, effectively saving energy and improving the power utilization satisfaction of users.

Intelligent power grid management system

CAN bus communication system was established mainly using SimEvents module in the software of Matlab/Simulink. Performance indexes of CAN bus system, which embraces worst-case response time of messages and bus load, were separately gained by theoretical calculation, experiments in Matlab and CANoe. The calculation and experiment results were compared sufficiently, and it concludes that CAN bus system established in Matlab/Simulink can efficiently represent the message transfer sequences on the CAN bus, and achieve an exact result of the performance analysis of the CAN bus system. With CAN bus system established in Matlab/Simulink, test modules for ECU (Electric Control Unit) testing can conveniently be created, and it is an efficient testing tool for CAN bus system design.

Fang Li

Papers

Path Following Control of Autonomous Ground Vehicle Based on Nonsingular Terminal Sliding Mode and Active Disturbance Rejection Control

Intelligent home system

Switch-On Modeling and Analysis of Dynamic Wireless Charging System Used for Electric Vehicles

Intelligent power grid management system

CAN(Controller Area Network) Bus Communication System Based on Matlab/Simulink