Chenglin Liao

Compensate Capacitor Optimization for Kilowatt-Level Magnetically Resonant Wireless Charging System

Magnetically resonant wireless power transfer (WPT) technique excels in delivering power over a relatively long distance, and WPT systems for bio-implants have been successfully developed. However, the preconception of resonant-operating results in a fact that most previous works pay little attention to the optimization of the compensate capacitors; these design methods cannot meet the newly arisen challenges when designing a high-power wireless charging system (WCS) for electric vehicles (EVs). This paper presents a design method featuring compensate capacitor optimizing for better design of practical kilowatt-level WCS. Comparison with conventional frequency tuning method is made based on equivalent circuit model analysis. Compensating characteristics of a typical WCS are studied to find out how the compensate capacitors affect the systemic performance. Furthermore, considering peculiar constraints and requirements of EV-oriented WCS, we present detailed optimizing procedure and adjustment criterion. Finally, correctness and effectiveness of the proposed optimizing method are verified by a 3.3-kW wireless charging prototype. A transfer efficiency value of 92% over 21 cm and 88.5% over 36 cm is achieved; voltages of the transmit and receive coils are simultaneously minimized and balanced for security.

Applying LCC Compensation Network to Dynamic Wireless EV Charging System

Based on the wireless power transfer (WPT) technology, dynamic wireless charging of electric vehicle (EV) is gaining increasing attentions because it promotes the popularization of EV and also serves a new form of clean transportation. In this paper, we introduce the LCC compensation network to WPT system oriented for dynamic wireless EV charging application. First, characteristics of symmetrical T-type network, which is the origin of the favorable LCC compensation network, are summarized. Then, parametric design for both the LCC network used in the secondary side and the LCC network used in the primary side is elaborated theoretically. Furthermore, neighboring effects resulting from the combination of the LCC compensation network and the inevitable inter-coupling between adjacent segments are investigated. Finally, a two-segment LCC compensated dynamic EV charging system is built up and tested with both intra-segment and inter-segment experiments. Spatially averaged output power and dc-dc efficiency of the prototype are measured to be 2.34 kW and 91.3%, respectively. High consistency of the experimental results validates the correctness of the proposed analyses and parametric design method, as well as the suitability of applying LCC network in dynamic wireless EV charging applications.

Improving the Misalignment Tolerance of Wireless Charging System by Optimizing the Compensate Capacitor

In this paper, we present a simple method to extend the feasible rated charging zone of a four-coil coupled wireless charging system (WCS) by optimizing the compensate capacitors of the coils. With the proposed optimizing method, the tolerant lateral misalignment of our WCS prototype has been extended to 44.3% of the coil size, achieving a 38.3% relative improvement.

Research on Improved EKF Algorithm Applied on Estimate EV Battery SOC

The paper mainly described how to estimate the state of battery charge (SOC) on electric vehicle (EV). Having deeply researched the lithium-ion (LiFePO4) battery characteristic, the paper established a kind of new battery equivalent circuit model. Meanwhile the paper improved the traditional EKF SOC estimate algorithm, including add the battery internal resistance as a new state variable, real time adjust the observation error variance Rk and add the gain factor to control the convergence speed. Through simulating analysis, the new method estimated error of SOC is less than traditional estimate method.

Research on State-of-Charge Estimation of Battery Pack Used on Hybrid Electric Vehicle

A dynamic model considering hysteresis effect and this paper, a dynamic model for NiMH battery pack is polarization effect and based on tests and parameter estimation is proposed and applied in Extended Kalman Filter (EKF) proposed to describe the dynamic characteristics of NiMH method. battery pack on Hybrid Electric Vehicle (HEV) with high precision. With the dynamic model, State-of-Charge (SOC) II. DYNAMIC BATTERY MODEL BULDING estimation method is derived based on Extended Kalman Filter The internal chemical reaction in the battery is so (EKF). Simulation results over different tests show that the complicated that it is difficult to build a good battery model dynamic model can simulate the output characteristics of NiMH theoretically. In this paper, a dynamic model is proposed battery pack more accurately and the SOC estimation method according to voltage characteristics analysis of NiMH battery based on the model is adaptive for HEV. pack. Different values of current pulse charge and discharge Keywords-hybrid electric vehicles; NiMH battery pack; battery tests have been done at constant temperature 25 with the test dynamic model; state of charge; Extended Kalman Filter instrument named Bitrode FTN400-450, which can measure voltage, current and SOC accurately. 6 Ah NiMH battery pack

SOC Estimation of LiFeO4 Battery Energy Storage System

Battery energy storage system as the voltage regulator device is widely used in distributed power generation system. LiFeO4 battery has broad application prospects in the energy storage system. Based on a large number of test data, the characteristic of LiFeO4 battery is analyzed systemically, and the battery equivalent circuit model is established. SOC estimation algorithm of LiFeO4 battery is got according to the extended Kalman filter (EKF) theory. In order to improve the estimation accuracy of SOC, the improvement of three aspects has been applied in the improved EKF method. The offline simulation results show that the improved EKF can improve the accuracy of SOC estimation effectively.

Reliability Research for Steer-by-Wire System of Electric Vehicle

Steer-by-wire System of Electric Vehicle must meet the advantages of both protocols. It is reported that the FlexRay real-time and reliability requirements. An approach in how to will very likely become the de-facto standard for in-vehicle estimate the reliability of Steer-by-wire system considering the communications. The fault-tolerant design of the channels and delay caused by network transmission errors is proposed. In the the protocol make FlexRay Bus having a great advantage paper, a distributed architecture of Steer-by-wire system is applied in the steer-by-wire system. researched to analyze the delay time of the system, and design the TDMA slots of FlexRay Bus. In addition, the reliability of the In the paper a distributed architecture of steer-by-wire system is calculated. The maximum tolerable response time of the system is firstly described, in which simplified control method system is performed by using Matlab/Simulink and other is shown. Then, based on the analyzing of the delay time of parameters of the system based on our experiment platform. The the system, the time division multiple access (TDMA) slots of results show that when the probability of losing one cycle is less the FlexRay Bus is designed, in which deferent sequences of than 0.1, the reliability of the system achieves the design goal. the slots will cause deferent transmission delays. Finally, The approach in this work can be taken as a reference for quantification of the reliability is done to obtain the system designing Steer-by-wire system of electric vehicle. tolerance for the rate of FlexRay error frame under the design requirement of reliability. SYSTEM NTRODUCTION With the worlds energy crisis and the worsening A. The Architecture of Steer-by-wire System environment, research of electric vehicle is emphasized more and more, and steer-by-wire system of electric vehicle has been put on the agenda. Steer-by-wire system is one in which conventional mechanical links between the steering wheel and the front wheels are removed, and is operated by electrical actors. Due to the importance of vehicle safety, such electrical systems must satisfy both stringent real-time performance and reliability requirements. However, so far, quantitative standards for automotive steer-by-wire reliability do not exist. As the references show, standards developed for aircraft can be applied, which quantify a rate of one failure occurring in one billion operating hours, or 10 −9

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

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.

Evaluating the communication impact on quality of service in steer-by-wire systems

X-by-Wire is a generic term referring to the replacement of mechanical or hydraulic systems, such as braking or steering, by electronic ones. The control of x-by-wire systems depends on communication network (like CAN, TTCAN or FlexRay), it must meet not only the control performance, but also the real-time requirements. This paper presents a system approach for evaluating the communication impact on steer-by-wire systemspsila control performance taking into account the message period, delay variation and network faults that probably introduced by network transmission. Steer-by-wire systempsilas simulation model are established in Matlab/Simulink environment, which mainly includes hand wheel node, road wheel node and network module. Several simulations have been carried out to estimate the impact of communication on the quality of service (Qos, for example, side slip angle waveforms) of steer-by-wire system and some critic limits are gained. The results of our work can be taken as a reference to design and improve the reliability of communication protocol in steer-by-wire systems to meet the control and real-time requirement.

Null-Coupled Electromagnetic Field Canceling Coil for Wireless Power Transfer System

In this paper, we present a kind of null-coupled canceling (NCC) coil to shield electromagnetic fields (EMFs) for wireless power transfer (WPT) systems. The proposed NCC coil is based on the particular zero-mutual-inductance characteristic between two general coils. The working principles, shielding effectiveness, and practical expansions of the proposed NCC coil are illustrated. Furthermore, locating of the zero-mutual-inductance position and determination of the canceling coil current are elaborated, and effects that an NCC coil exerts on the output power, efficiency, and misalignment tolerance of the applied WPT system are theoretically studied. Finally, targeted at our predesigned electric vehicle wireless charging-oriented WPT prototype, a practical NCC coil is built and tested with comparative experiments with the prevalent aluminum (Al) plate shielding. The experimental results show that, with a properly chosen canceling current, the proposed NCC coil could not only shield the EMF more effectively, but also cause a lower efficiency reduction to the applied WPT system than an Al-plate does.