Abstract: Lithium-ion power battery has become one of the main power sources for electric vehicles and hybrid electric vehicles because of superior performance compared with other power sources. In order to ensure the safety and improve the performance, the maximum operating temperature and local temperature difference of batteries must be maintained in an appropriate range. The effect of temperature on the capacity fade and aging are simply investigated. The electrode structure, including electrode thickness, particle size and porosity, are analyzed. It is found that all of them have significant influences on the heat generation of battery. Details of various thermal management technologies, namely air based, phase change material based, heat pipe based and liquid based, are discussed and compared from the perspective of improving the external heat dissipation. The selection of different battery thermal management (BTM) technologies should be based on the cooling demand and applications, and liquid cooling is suggested being the most suitable method for large-scale battery pack charged/discharged at higher C-rate and in high-temperature environment. The thermal safety in the respect of propagation and suppression of thermal runaway is analyzed.

Abstract: Light-weight high-temperature alloys are important to the transportation industry where weight, cost, and operating temperature are major factors in the design of energy efficient vehicles. Aluminum alloys fill this gap economically but lack high-temperature mechanical performance. Alloying aluminum with cerium creates a highly castable alloy, compatible with traditional aluminum alloy additions, that exhibits dramatically improved high-temperature performance. These compositions display a room temperature ultimate tensile strength of 400 MPa and yield strength of 320 MPa, with 80% mechanical property retention at 240 °C. A mechanism is identified that addresses the mechanical property stability of the Al-alloys to at least 300 °C and their microstructural stability to above 500 °C which may enable applications without the need for heat treatment. Finally, neutron diffraction under load provides insight into the unusual mechanisms driving the mechanical strength.

Abstract: For commercial one-sun solar modules, up to 80% of the incoming sunlight may be dissipated as heat, potentially raising the temperature 20–30 °C higher than the ambient. In the long term, extreme self-heating erodes efficiency and shortens lifetime, thereby dramatically reducing the total energy output. Therefore, it is critically important to develop effective and practical (and preferably passive) cooling methods to reduce operating temperature of photovoltaic (PV) modules. In this paper, we explore two fundamental (but often overlooked) origins of PV self-heating, namely, sub-bandgap absorption and imperfect thermal radiation. The analysis suggests that we redesign the optical properties of the solar module to eliminate parasitic absorption ( selective-spectral cooling ) and enhance thermal emission ( radiative cooling ). Comprehensive opto-electro-thermal simulation shows that the proposed techniques would cool one-sun terrestrial solar modules up to 10 °C. This self-cooling would substantially extend the lifetime for solar modules, with corresponding increase in energy yields and reduced levelized cost of electricity.

Abstract: The purpose of this paper is to analyze and investigate the influence of temperature variation on the characteristics and performance of interior permanent magnet (IPM) machines. The impact of temperature variation on the materials of IPM machines is discussed to show the sources of performance variation. The flux linkages, torque output capability, and inductance variation as functions of the temperature are analyzed and discussed. This paper also shows the influence of temperature variation on key IPM machines performance including constant torque curves, voltage limit ellipses, maximum torque per ampere trajectories, and torque-speed curves. Experimental results of a traction IPM machine verified the analysis and theory. The results and trends shown in this paper set a foundation for developing control algorithm, which takes the temperature effects into consideration, especially in the applications where operating temperature varies significantly.

Abstract: This paper presents the implementation of a high-resolution time-to-digital converter (TDC), which is adapted to varying environmental conditions. The TDC is implemented in field-programmable gate arrays (FPGA), using carry chains to achieve fine time measurement. Multiple carry chains are integrated in a single TDC channel for resolution enhancement. The TDC performance would suffer greatly without temperature compensation due to its sensitivity to the operating temperature. In order to improve the TDC adaptability, we analyzed the temperature-dependent delay variation function, and designed a powerful offset canceler to ensure stable performance of our TDC over a wide temperature range. The offset canceler can effectively correct the delay offset over temperature for the carry chain as well as for the signal transmission path. The TDC channels are tested to be fully functional with the operating temperature continuously varying from −20 °C to 60 °C. The averaged TDC bin size is 1.15 ps, and the single-shot precision is 3.5 ps. The duplications of the TDCs in three FPGA chips show good performance reproducibility according to the tests in a temperature chamber.

Abstract: Polymer Electrolyte Membrane Fuel Cells (PEMFC) is an electrochemical device that generates electrical energy from the reactions between hydrogen and oxygen. An effective thermal management is needed to preserve the fuel cell performance and durability. Cooling by water is a conventional approach for PEMFC. Balance between optimal operating temperature, temperature uniformity and fast cooling response is a continuous issue in the thermal management of PEMFC. Various cooling strategies have been proposed for water-cooled PEMFC and an approach to obtain a fast cooling response was tested by feeding the coolant at a high temperature. In this paper, the operating behaviour was characterized from the perspectives of temperature profiles, mean temperature difference, and cooling response time. A 2.4 kW water-cooled PEMFC was used and the electrical load ranged from 40 A–90 A. The operating coolant temperature was set to 50 °C where the maximum stack operating temperature is 60 °C. The stack temperature profiles, cooling response time, mean temperature difference and cooling rates to the load variation was analysed. The analysis showed that the strategy allowed a fast cooling response especially at high current densities, but it also promotes a large temperature gradient across the stack.

Abstract: For the optical current sensor that combines FBG and magnetostrictive material, a key problem is that the performance of FBG and magnetostrictive material is influenced by the operating temperature. In this paper, in order to overcome this problem, we proposed a method of temperature compensation based on the dual FBG configuration, which can make the measuring result of magnetic field be essentially temperature independent. In this method, two FBGs with the same type are bonded on two giant magnetostrictive materials, respectively. The two giant magnetostrictive materials have the identical shape and come from the same bulk material, while they have the orthogonal magnetostriction directions. We perform the experiment to investigate the performance of this method at different temperatures and at different magnetic fields, in order to verify the feasibility of this method. The experiment results demonstrate that this method significantly decreases the influence of temperature, and thus it can maintain a relative good performance in the temperature range of 20 °C–70 °C.