Temperature rise of the hub motor in distributed drive electric vehicles (DDEVs) under long-time and overload operating conditions brings parameter drift and degrades the performance of the motor. A novel online parameter identification method based on improved teaching-learning-based optimization (ITLBO) is proposed to estimate the stator resistance, ��-axis inductance, ��-axis inductance, and flux linkage of the hub motor with respect to temperature rise. The effect of temperature rise on the stator resistance, ��-axis inductance, ��-axis inductance, and magnetic flux linkage is analysed. The hub motor parameters are identified offline. The proposed ITLBO algorithm is introduced to estimate the parameters online. The Gaussian perturbation function is employed to optimize the TLBO algorithm and improve the identification speed and accuracy. The mechanisms of group learning and low-ranking elimination are established. After that, the proposed ITLBO algorithm for parameter identification is employed to identify the hub motor parameters online on the test bench. Compared with other parameter identification algorithms, both simulation and experimental results show the proposed ITLBO algorithm has rapid convergence and a higher convergence precision, by which the robustness of the algorithm is effectively verified. Keywords: parameters identification, teaching–learning-based optimization, hub motor, temperature rise.

Exergy analysis is a powerful thermodynamic tool and it helps in computing the actual output of a system. It helps the researchers to optimize the roughened solar air heater design to compensate the present and also the future needs. In this study, investigation on exergetic performance evaluation of a solar air heater with W-shaped roughened absorber surface analytically by employing mathematical model and the results obtained are compared with smooth plate solar air heater under same operating conditions. The exergetic efficiency curves has been plotted as a function of different values of Reynolds number and temperature rise parameter for different roughness parameters. The maximum augmentation in the exergetic efficiency of the solar air heater with W-shaped roughened surface as compared to solar air heater with smooth surface has been obtained as 51% corresponding to the relative roughness height of 0.03375 and the rib angle of attack about 60◦. Based on the exergetic efficiency the suitable design parameters of solar air heater with W-shaped roughened are determined.

For the sake of exploring the thermodynamic characteristics of hybrid ceramic bearings with metal inner rings in the application process, we established the mathematical model of bearings with metal inner rings based on the thermodynamics of bearings. The heat of the bearings, inner and outer raceway, and the deformation of bearings were calculated by the thermodynamic model. We used the bearing life testing machine to test the bearing load and speed. The consequences indicate that the temperature stability time of a hybrid ceramic bearing with the metal inner ring is about 6 hours after loading, and its temperature is about 1–2°C higher than that of a metal bearing. Under the condition of a certain speed, the stable temperature of bearing operation improves with the enlargement of the load. Under the condition of a certain load, the bearing temperature also improves with the enlargement of bearing speed. The overall temperature trend of the bearing outer ring is unanimous with the overall temperature value calculated by the model. The maximum error is between 2.2 and 2.4°C. The thermodynamic analysis of hybrid bearings with metal inner rings is conducive to a better study of the effect of bearing material characteristics on bearing performance.