Xia Chaoying is a professor at School of Electrical and Information Engineering, Tianjin University, doctoral supervisor. His main research interests include control theory and applications, power electronics technology and device, Ac speed regulation technology and device for permanent magnet motor and asynchronous motor, new energy vehicles and hybrid vehicles drive technology and device. His published papers include mainly，(1) Conjecture about the absolute stability problems of SIMO and MISO systems and a proof of its deduction (IEE Proceedings-Control Theory and Applications, Vol 148, No 4, 2001), (2) The HEV energy optimization for reducing peak and filling valley energy-saving effect is explained in theory (Energies, 8(11): 12458-12473, 2015; SCIENCE CHINA Technological Sciences, 56(5)814-824, 2016; Energies, 2017, 10(7): 896. ) (3) Research on feedback linearization control strategy and improved direct torque control of brushless doubly-fed machine (International Journal of Precision Engineering and Manufacturing, 16(8): 1699-1709, 2015; Energies. 2016, 9(11), 966).