Improved Real-time State-of-Charge Estimation of LiFePO4 Battery Based on a Novel Thermoelectric Model

Li-ion batteries have been widely used in electric vehicles, and battery internal state estimation plays an important role in the battery management system. However, it is technically challenging, in particular, for the estimation of the battery internal temperature and state-ofcharge (SOC), which are two key state variables affecting the battery performance. In this paper, a novel method is proposed for realtime simultaneous estimation of these two internal states, thus leading to a significantly improved battery model for realtime SOC estimation. To achieve this, a simplified battery thermoelectric model is firstly built, which couples a thermal submodel and an electrical submodel. The interactions between the battery thermal and electrical behaviours are captured, thus offering a comprehensive description of the battery thermal and electrical behaviour. To achieve more accurate internal state estimations, the model is trained by the simulation error minimization method, and model parameters are optimized by a hybrid optimization method combining a meta-heuristic algorithm and the least square approach. Further, timevarying model parameters under different heat dissipation conditions are considered, and a joint extended Kalman filter is used to simultaneously estimate both the battery internal states and time-varying model parameters in realtime. Experimental results based on the testing data of LiFePO4 batteries confirm the efficacy of the proposed method.

Los estados de excepción en Colombia y aplicación del principio de proporcionalidad: un análisis de seis casos representativos

El artículo que se presenta a continuación da cuenta de cómo ha funcionado el principio de proporcionalidad en Colombia en el control de constitucionalidad de las declaratorias de los estados de excepción, a través de la evaluación de seis (6) casos de excepcionalidad a partir de 1991, cuatro (4) de ellos referidosa estados de conmoción interior, y dos (2) referidos a emergencias sociales. Se utilizó una metodología cualitativa que permitió describir la forma como la Corte Constitucional aplicaba o no el principio de proporcionalidad para hacer el examen de dichas excepcionalidades, dando cuenta de una matriz de análisis que describe los puntos clave de dicho principio, a saber: a) laexistencia de una crisis coyuntural y no de un daño estructural en cualquiera de los estados de excepción declarados; b) la no suspensión de los derechos humanos ni de las libertades fundamentales de las personas a quienes van dirigidas las medidas incluidas en este; c) la no interrupción del normal funcionamiento de las ramas del poder público; d) el ejercicio de las facultades solo para enfrentar eficazmente la anormalidad; la relación estricta entrecausa y anormalidad, y, en este sentido, la dirección de los decretos única y exclusivamente a conjurar las causas que dan origen a la excepcionalidad; e) la duración definida de los estados de excepción (Cifuentes, 2002), para concluir que la Corte Constitucional, en su aplicación del principio de proporcionalidad, no ha realizado un juicio exhaustivo de los requisitos que este incorpora, de tal forma que ha permitido una perpetuación del poder presidencial y un gobierno con poca separación de poderes.

DYNAMIC MODEL BASED STATE ESTIMATION IN A HEAVY DUTY DIESEL AFTERTREATMENT SYSTEM FOR ONBOARD DIAGNOSTICS AND CONTROLS

Estimating un-measurable states is an important component for onboard diagnostics (OBD) and control strategy development in diesel exhaust aftertreatment systems. This research focuses on the development of an Extended Kalman Filter (EKF) based state estimator for two of the main components in a diesel engine aftertreatment system: the Diesel Oxidation Catalyst (DOC) and the Selective Catalytic Reduction (SCR) catalyst. One of the key areas of interest is the performance of these estimators when the catalyzed particulate filter (CPF) is being actively regenerated. In this study, model reduction techniques were developed and used to develop reduced order models from the 1D models used to simulate the DOC and SCR. As a result of order reduction, the number of states in the estimator is reduced from 12 to 1 per element for the DOC and 12 to 2 per element for the SCR. The reduced order models were simulated on the experimental data and compared to the high fidelity model and the experimental data. The results show that the effect of eliminating the heat transfer and mass transfer coefficients are not significant on the performance of the reduced order models. This is shown by an insignificant change in the kinetic parameters between the reduced order and 1D model for simulating the experimental data. An EKF based estimator to estimate the internal states of the DOC and SCR was developed. The DOC and SCR estimators were simulated on the experimental data to show that the estimator provides improved estimation of states compared to a reduced order model. The results showed that using the temperature measurement at the DOC outlet improved the estimates of the CO , NO , NO2 and HC concentrations from the DOC. The SCR estimator was used to evaluate the effect of NH3 and NOX sensors on state estimation quality. Three sensor combinations of NOX sensor only, NH3 sensor only and both NOX and NH3 sensors were evaluated. The NOX only configuration had the worst performance, the NH3 sensor only configuration was in the middle and both the NOX and NH3 sensor combination provided the best performance.

Internal and external fluctuations around nonequilibrium steady states in one-dimensional heat-conduction problems

Thermal fluctuations around inhomogeneous nonequilibrium steady states of one-dimensional rigid heat conductors are analyzed in the framework of generalized fluctuating hydrodynamics. The effect of an external source of noise is also considered. External fluctuations come from temperature and position fluctuations of the source. Contributions of each kind of noise to the temperature correlation function are computed and compared through the study of its asymptotic behavior.