A framework for battery internal temperature and state-of-charge estimation based on fractional-order thermoelectric model

In recent years, the rapid development of electric vehicles has raised a wave of innovation in lithium-ion batteries. The safety operation of lithium-ion batteries is one of the major bottlenecks restraining the development of the energy storage market. The temperature especially the internal temperature can significantly affect the performance and safety of the battery; therefore, this paper presented a novel framework for joint estimation of the internal temperature and state-of-charge of the battery based on a fractional-order thermoelectric model. Due to the nonlinearity, coupling, and time-varying parameters of lithium-ion batteries, a fractional-order thermoelectric model which is suitable for a wide temperature range is first established to simulate the battery’s thermodynamic and electrical properties. The parameters of the model are identified by the electrochemical impedance spectroscopy experiments and particle swarm optimization method at six different temperatures, and then the relationship between parameters and temperature is obtained. Finally, the framework for joint estimation of both the cell internal temperature and the state-of-charge is presented based on the model-based state observer. The experimental results under different operation conditions indicated that, compared with the traditional off-line prediction method, the model-based online estimation method not only shows stronger robustness under different initial conditions but also has better accuracy. Specifically, the absolute mean error of the estimation of state-of-charge and internal temperature based on the proposed method is about 0.5% and 0.3°C respectively, which is about half of that based on the off-line prediction method.

Thermoelectric model of the Earth's magnetic field

A variant of the thermoelectric model of the Earth's dipole magnetic field is considered. It is based on geothermoelectric currents present in the planet's core. The currents cyclically change their direction, which leads over time either to warming on the Earth, if their movement is directed towards the Earth's crust, or to cooling, when moving towards the inner core. With each change in the direction of movement of the thermal currents, the poles of the Earth's magnetic field are inverted simultaneously. The inversion process is instantaneous (on the scale of planetary time) and is not the result of a gradual reversal on the 180° Earth's magnetic axis. At the moment of inversions of thermal currents in the core, the total geomagnetic field decreases to the level of 4.6∙10-6 T, which is constantly supported by thermal currents of semi-conducting rocks of the lower mantle. The considered version of the thermoelectric model of the Earth's magnetic field may be promising for studying the magnetic fields of planets in the Solar system.

Determination of transient thermal characteristics for thermal electric behavioral models of integrated circuits

In the current study, it was tried to describe a method for determining thermal characteristics of integrated micro-circuits to identify thermal parameters of multidisciplinary (thermal-electric) behavioral models. The problem is solved on the example of high-frequency pulse voltage converters. A solution was proposed to refine the minimum structure of the thermoelectric model based on an iterative least squares method using the Levenberg-Marquardt algorithm, as well as a graph of the spectral den-sity of time constants. This made it possible to reduce the influence of the filtering factor in the deconvolution operation when building a thermal model using the structural function of the thermal characteristic transition. Also, the results obtained can be used to build integrated circuits (IC) behavioral models, taking into account the thermal processes occurring in them.

The simulation analysis of composite parabolic concentrator to improve the performance of thermoelectric devices

The collection and reuse of thermal radiation energy generated by high-temperature objects has always been the focus of attention and research. Here we designed and fabricated a compound parabolic concentrator (CPC) that can be used for infrared radiation energy collection based on non-imaging optical technology. The energy gathered by CPC has a significant effect on the improvement of the surface temperature of objects. The thermoelectric (TE) generator is a good choice to utilize this thermal energy. This paper analyses and discusses the effects of CPC on the performance of thermoelectric model by simulation. The result has well demonstrated that the TE model with CPC has not only a considerable reduction in structure size and material consumption, but also ensures higher output power and efficiency. In addition, we propose that the array of CPC shall prominently enhance the performance of thermoelectric device.

ANALYSIS OF METHODS FOR DETERMINING AND APPLYING HEAT PARAMETERS OF HIGH FREQUENCY PULSE VOLTAGE CONVERTERS

It is shown that the thermal resistance of the junction-case is determined through a partial heat flux and is some characteristic of the crystal fastening in the case of high-frequency pulse voltage converters. It is practically impossible to measure this resistance in mass production because of the high complexity and low accuracy, although this resistance is indicated in the reference data sheet for each IC. To exclude the possibility of hidden defects that are not detected during the control of electrical parameters, it is proposed to use one hundred percent control of thermal parameters by way of comparison with a standard. The transient thermal characteristic can be determined experimentally for a specific IC and specific cooling conditions. After approximation by its exponents, it is possible to construct a thermoelectric model and use it to study the change in the temperature of the IC chip with changing various parameters (supply voltage, load power, etc.).