Liye Wang

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 battery balance system applied on HEV

The inconsistent of characters parameters of the batteries for HEV severely decreases the performance of the vehicle, so it is very important to research on batter balancing system. This paper reviews the disadvantages of previous battery balancing system, then presents a new battery balancing scheme applied on HEV. The proposed scheme can distribute energy automatic according to the battery energy level of inconsistency. Because of the high efficiency of energy transfer, the scheme suit battery pack applied on HEV which need large fluctuations of working current and frequent charge-discharge conversion.

Sigma-point Kalman filter application on estimating battery SOC

For the Extended Kalman Filter (EKF) not easy to adjust, difficult to apply on system of updating step time, and its linearization process may generate error of approximation, in recent year, some new methods about expansion Kalman filter to nonlinear system have been proposed. This paper present a new method that Sigma-point Kalman filter estimate SOC through the use of weighted statistical linear regression (WSLR) method for solving linear equations. So this method compared with the traditional EKF method can expect to receive a smaller linearization error. Design a test and apply this method on estimate battery SOC.

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.

Effects of operation frequency and current on coil impedance of EV wireless charging system

This paper presents an analysis of operation frequency and current effects on coil impedance and system characteristics of electric vehicle (EV) wireless charging system. Firstly, an equivalent circuit model of EV wireless charging system with dual side LCC compensation networks is established. Also, power loss and system efficiency expressions are given. Then, frequency influence is studied considering Litz wire used for the coils. Furthermore, effects of frequency and current are analyzed based on parameter measurements and tests. Finally, efficiency and output power change curves are given to show the impacts of frequency- and current-dependent coil impedances on system characteristics.

Based on energy transferring for battery packs applied on Electric Vehicle

A new nondissipative battery balance scheme for battery pack is proposed in this paper. The proposed scheme comprise a balance modular with an energy transferring inductance, switch mosfet and transformer. Simulation and experimental results show that the proposed battery balance scheme can balance the battery cells voltage and increase the battery using efficiency. Furthmore, the balance scheme can be extend easily, this balance scheme also can easy to apply on Electric Vehicle.