Online Parameter Estimation Method Research Articles

Online Estimation of Double-Star IPM Machine Parameters Using RLS Algorithm

Accurate and updated knowledge of the electric machine parameters provides benefits in many applications, such as model-based control methods. This paper presents an online parameter estimation method for double-star interior permanent-magnet (IPM) machines supplied with voltage-source inverters (VSI). The estimation method is based on a decoupled D-Q model of the machine and a recursive least-squares (RLS) algorithm. Initial machine parameters are estimated at a standstill. Then, in the rotating operating state, the inductances and the flux linkage produced by the PMs are updated. The estimation in the operating state is performed with a flux-linkage-based approach. The experimental results are compared with the corresponding values obtained from finite-element analyses. The results show an acceptable agreement and demonstrate the feasibility of the estimation scheme to estimate the parameters of double-star PM machines. The parameters are validated by comparing experimental and simulated open-loop responses and steady-state torques.

Estimation of State of Charge, Unknown Nonlinearities, and State of Health of a Lithium-Ion Battery Based on a Comprehensive Unobservable Model

This paper considers the estimation of the state of charge and state of health for lithium-ion batteries, while an inclusive model is taken into account. The model includes two RC subnetworks, which represent the fast and slow transient responses of the terminal voltage. Nevertheless, the linear part of the model is unobservable. On the other hand, the nonlinear behavior of the open-circuit voltage versus state of charge is also included in the model. The proposed observer tackles the aforementioned problems to attain a reliable estimation of the state of charge. Moreover, as opposed to the methods in which the nonlinearities or uncertainties in the model are disregarded or those terms are discarded using a conventional sliding-mode observer, an analytical method is considered to estimate the additive nonlinear or uncertainty term in the model. This approach leads to a very accurate model of the battery to be used in a battery management system. Moreover, an online parameter estimation method is proposed to estimate the battery's state of health. The proposed scheme benefits from an adaptive rule for the online estimation of the series resistance in the lithium-ion battery based on the accurately identified model. Experimental tests certify the performance and feasibility of the proposed schemes.

Frequency and Time Domain Recursive Parameter Estimation For a Flexible Aircraft

Aerodynamic parameter estimation is an integral part of aerospace system design and life cycle process. Recent advances in computational power have allowed the use of online parameter estimation techniques in various applications. In this paper, two online parameter estimation methods are considered for the identification of aerodynamic derivatives of a flexible aircraft: Equation Error Method and Kalman Filtering Method. The performance of the two algorithms is compared in terms of accuracy, computational efficiency and convergence. Simulation results indicate that Kalman filtering method has good convergence property and yields parameter estimates with better accuracy compared to the equation error method.

On-line Parameter Estimation Method for IPMSM Based on Decoupling Control

This paper proposed on-line parameter estimation method to compensate the magnetic cross-saturation effect on the interior permanent magnet synchronous motor (IPMSM) control system for electric vehicle. The decoupling control model for IPMSM with magnetic saturation compensation based on SVPWM (Space Vector PWM) method is established. Though comparing the simulation results between model with saturation compensation of parameter estimation and ones without saturation compensation, it is verified that the control performance with saturation compensation is more stable and more accurate than that of without compensation over speed operating region especially at higher speed. The on-line parameter estimation method based on decoupling control improves the system following-up performance, robustness and the control accuracy effectively.

A recursive algorithm for bearings-only tracking with signal time delay

For the bearings-only tracking (BOT) problem with signal propagation time delay, a recursive algorithm is proposed. Based on the analysis of signal time delay effect, an online parameter estimation (OPE) method is presented, which can be embedded in nonlinear filters to recursively estimate the target state with delayed measurements. The nonlinear filter used in this paper is a combination of the kernel-based filter (KBF) with an improved range parameterized (IRP) method, which manages subintervals according to their corresponding weights. The effectiveness and advantages of our proposed method compared with two existing methods are demonstrated by simulation examples.

On-line Parameter Estimation of Time-varying Systems by Radial Basis Function Networks

This paper proposes a new on-line parameter estimation method with radial basis function networks for time-varying linear discrete-time systems. The time-varying parameters of the system are expressed with the radial basis function networks. These parameters are estimated by the nonlinear optimization technique, and the setting rules of the initial values in the optimization are proposed. The system parameters are usually unknown because they are changed by the circumstance conditions. Then, it is reasonable that the structures of the radial basis function networks are regulated according to the change of parameters. The minimum description length criterion studied in the encoding theory is applied to select the network structures. It is demonstrated in digital simulation that the proposed on-line estimation method succeeded to reduce the computaion time extremely, for time-varying parameters system.

Nonlinear model-based control in the biological waste-water treatment system

The dissolved oxygen (DO) concentration has been an important process parameter in the biological wastewater treatment system. A new strategy for designing a nonlinear model-based control is developed. The proposed controller can be incorporated directly with the nonlinear DO process model obtained by on-line parameter estimation method without any Iinearization or model reduction. Since the model-based nonlinear control incorporates the process disturbance and nonlinearity effectively, the suggested method can efficiently treat the operating condition. The simulation results show that the proposed control strategy outperforms the normal control strategy that uses a standard PID controller.

Selftuning and Adaptive Control with Personal Computers

Abstract Personal Computers (PC) with process interface are well suited to develop and to test control algorithms in on-line operation with the process. The application of a PC in connection with adaptive control strategies increases the control quality and reduces the costs of implementation. In this paper the possibilities of the use of PC’s for the design of digital controllers will be shown. One important prerequisite for the use of optimized control concepts is the knowledge about the process to be controlled. PC’s can be used for the determination of a process model by application of on-line parameter-estimation methods. The application of two programs for selftuning and adaptive control CADREG-PC and ADAREG-PC are shown.

Flank Wear Estimation Under Varying Cutting Conditions

A model-based methodology, designed to operate under varying cutting conditions, for on-line estimation of flank-wear rate based on cutting force measurements is introduced. The key idea is to employ a model of the relationship between force and flank wear, together with on-line parameter estimation methods. This permits separation of the direct effect of changing cutting conditions on force from the indirect effect where changing cutting conditions affect the wear which, in turn, affects the force. Simulation results confirm the effectiveness of this strategy for turning with varying speed, feed, or depth of cut. Experiments, conducted for turning operations with a varying depth of cut, show good agreement between estimated wear values and the actual values of tool wear measured intermittently during the cut.

Boundary Identification for a Two-Dimensional Diffusion System Under Noisy Observations

This paper is concerned with the boundary identification problem for a diffusion system under noisy observations. First, the system domain with a partially unknown boundary is given by the bounded set in R(2) . For the system governed by a two-dimensional diffusion equation, noisy observation data are acquired through sensors allocated on the part of known boundary. Secondly, with background knowledge of maximum likelihood estimate, the on-line parameter estimation method is proposed in a form of recursive computation. A method for computer implementation of the proposed estimator is discussed by applying the boundary clement method. Finally, results of digital simulation experiments are shown for the purpose of supporting the theoretical aspect.

On-Line Parameter Estimation in Pass Scheduling for Plate Rolling

Good flatness and gauge of plates as well as high mill production are ensured by an uncomplicated dynamic pass scheduling system which is applicable both to rolling of ferrous and non-ferrous materials.This paper describes an on-line parameter estimation method, which is used for pass scheduling for plate rolling. The method does not require any complicated slab temperature model nor temperature measurement for the pass control. However, the actual rolling conditions are adaptively controlled by changing the parameters of the force model during rolling where a recursive calculating method is applied. The system has been checked against a plate temperature model, which is based on convection and radiation from the slab to the surroundings, conduction from the slab to the rolls and the heat-generation by deformation and friction. Only marginal improvement in accuracy was gained.