Wang Youyi

Li-ion battery SOC estimation using particle filter based on an equivalent circuit model

In this paper, a method for Li-ion battery state of charge (SOC) estimation using particle filter (PF) is proposed. The equivalent circuit model for Li-ion battery is established based on the available battery block in MATLAB/Simulink. To improve the models accuracy, the circuit parameters are represented by functions of SOC. Then, the PF algorithm is utilized to do SOC estimation for the battery model. From simulation it reveals that PF provides accurate SOC estimation. It is demonstrated that the proposed method is effective on Li-ion battery SOC estimation.

Li-ion battery SOC estimation using EKF based on a model proposed by extreme learning machine

In this paper, a method for modeling and estimation of Li-ion battery state of charge (SOC) using extreme learning machine (ELM) and extended Kalman filter (EKF) is proposed. The Li-ion battery model from ELM, which is established by training the data from the battery block in MATLAB/Simulation, could describe the dynamics of Li-ion battery very well. And it has higher accuracy and needs less calculation than using the traditional neural networks. Moreover, the battery model and discrete SOC definition equation constitute state-space equations, and EKF is used to estimate the SOC of Li-ion battery. Comparing the actual SOC with the estimated SOC by simulation, it reveals that the method proposed in this paper has good performance on Li-ion battery SOC estimation.

New variable structure control of dual-stage actuator servo systems

A dual-stage actuator servo system is a promising solution for very high-density disk drives of the future. The requirements for its transient response and robustness are much tighter than for a single-stage one. In this paper, a new variable structure controller with an optimal and dynamic sliding surface is developed to realize satisfactory track seeking and following. Moreover, the servo system with the controller can adopt parametric uncertainties and time variations, and has strong rejection to external disturbances. Simulation results for the closed-loop system are presented in the paper.

A TCPN model and deadlock avoidance for FMS jobshop scheduling and control system

Scheduling and control system of a FMS is complex because of the flexible production environment, dynamic changes of the system and orders, and dynamic decision requirement. Therefore a model that can handle such complicated system is necessary. In this article, a generic model for FMS jobshop scheduling and control system based on timed coloured Petri nets (TCPN) is proposed. A feedback structure to ensure that the TCPN model is deadlock free is designed. Based on the model, deadlock can be avoided regardless of what scheduling rules are used.

A fuzzy logic-based model for Li-ion battery with SOC and temperature effect

In this paper, a fuzzy logic-based model for Li-ion battery considering SOC and temperature effect is proposed. So far, the equivalent circuit model for Li-ion battery is common-used for its simplicity and suitability for control and estimation. However, among existing equivalent circuit models, it is seldom to consider the temperature effect, which has significant influence on electric vehicles (EVs) performance. It is difficult to find the relationship between equivalent circuit parameters and state of charge (SOC) and temperature. In our paper, the methodology of fuzzy logic is applied to model Li-ion battery. By using fuzzy rules, SOC and temperature effect on parameters is described simultaneously with simplicity and clarity. Simulation and experiment results show that the fuzzy logic-based model has good accuracy at different temperatures.

Current-limited voltage control strategies for multiple-input buck converters applied in renewable energy hybrid systems

Current-limited voltage control strategies (CLVCSs) are required by kinds of renewable energy hybrid systems. For small-scaled loads such as portable electronic devices and electric vehicles, multiple-input buck converters (MIBCs) are the preferred candidate, if introducing renewable energy sources to power them. In this paper, three CLVCSs-independence CLVCS, addition CLVCS, and subordination CLVCS-which are applied in the input-capacitor-added (ICA) MIBC topology, are put forward and compared based on the simulation stage. The results show, when designing the CLVCS structure, the consideration of building up a proper connection of the duty cycles, as the subordination CLVCS did, is able to improve the stability and robustness of the controlled output voltage of the ICA MIBC, whereas at the expense of less control accuracy of limiting the output current of the power source.

Mid-frequency Disturbance Rejection of HDD Systems

In this paper, we investigate mid-frequency disturbance rejection of hard disk drive servo systems. Generalized first-order reset element (GFORE) is proposed and used to construct a reset phase lead controller. The proposed phase lead controller is then used to compensate the phase lag caused by mid-frequency narrow band compensator without changing the gain property of the overall system. At last, the proposed reset compensator is applied to mid-frequency disturbance rejection of hard disk drive systems. Simulation results show that it can provide large open-loop gain around crossover frequency without degrading the transient response.

Improvement of tracking performances in hard disk drive servo via tracking-differentiator and composite nonlinear control

This paper deals with the design of hard disk drive (HDD) servo systems using a tracking differentiator (TD) and a composite nonlinear feedback (CNF) control to improve its tracking performances. The CNF law consists of linear and nonlinear feedback parts. The linear part is designed for fast rising time while the nonlinear part is designed to increase the damping ratio as the system output approaches the target value to minimize the overshoot during track following in the presence of actuator saturation. In order to reduce the impact of the control gains of both the above linear and nonlinear parts on the tracking performance, a tracking differentiator is used. This tracking differentiator generates a smooth approximation of the reference step input, so as to produce a smooth change of tracking error as the systems approach the final value. Thus the problems of the large or small gain control theory does not arise with this method. The stability of the CNF control law along with the TD is proved through appropriate Lyapunov function. The implementation results show that the proposed control design out-performs the conventional proximate time-optimal servomechanism.

FMS jobshop scheduling using Lagrangian relaxation method

This paper tackles a FMS jobshop scheduling problem with alternative routings. The objective function is to minimize the weighted flow time of jobs. We use Lagrangian relaxation method to relax the precedence constraints and propose a two-stage approach to solve the decomposed one-machine multi-operation problems. Three examples are tested and the computational results are compared to the Lagrangian relaxation method proposed by Hoitomt (1993). The comparison studies show that with the minimum weighted flow time of jobs as the objective of the scheduling problem the method proposed in this paper yields better solution with less computational time than the existing Lagrangian method.

Lookahead control policies and decision rules for dynamic scheduling of an FMS

In this paper, lookahead control policies and decision rules are proposed to solve the conflicts occurring in the TCPN model given by Meng et al. (1995) for FMS scheduling, assuming that some transitions are controllable. Simulation results show that the proposed approach has consistently better performance, for the objective of minimal flow time of jobs, when compared to simple dispatching rules. It is also obvious that when the job arrival distribution is not uniform, the job entry control becomes very important.