Prof. Wei Cai
Harbin University of Science and Technology
Foreign member of Russian Academy of Engineering

Title: Challenges and Solutions of Automotive 800VDC Platform and High Speed e-Motor Systems

Abstract: Clean e-power generation and vehicular electrification are the strategic planning in China.  The carbon emissions and toxic gas emissions are compared between the internal combustion engine vehicles and electric vehicles; The market of new energy vehicles (NEV) and the technology trend of NEV electric drive industry  summarized.  The onboard system voltage of 800VDC raised from below 400VDC facilitates fast battery charging, and the e-motor speed of above 25000rpm from 12000rpm benefits to reduction of  the size and weight of the e-powertrain. However the high voltage and the high switching frequency for controlling the motor challenge many respects of the electric machine systems, including power electronic inverters. The solutions to increase inverter efficiency, power density, temperature tolerance, reliability, and to improve EMC and NVH as well as durability  are given in the presentation.

Furthermore, some deep researches by my group at university towards upstream of e-powertrain industrial chain are reported  as follows.  A method to raise temperature tolerance of the capacitor film from 105℃ to 125℃ is proposed; The method to reduce parasitic inductance of SiC devices and to improve inverter EMC, the sintered package are introduced to replace bond-wire package, and the required potting resin and plastic sealant as well as sintered materials like silver paste, copper paste are developed by our group. The software algorithm to lower shaft voltage and shaft current is described, through which the bearing ablation due to shaft current  is reduced.  The demands and challenges of e-powertrains for various sub assemblies, motor parts / power electronic components and materials etc., are described, which could be referenced by researchers and engineers.

Biography: William Cai received his Ph.D. in ECE from Clarkson University, NY, USA, and his B.S. and M.S. from Harbin Electric Institute of Technology(HEIT).  Currently, he is the Professor of Harbin University of Science and Technology(HUST), Harbin, China, and chief scientist of the State Education Ministry Engineering Research Center of Automotive Electronic Drive Control and System Integration. He is the adjunct professor of Beijing Institute of Technology, Beijing Jiaotong University, Southeast China University etc., and the Foreign Academician of the Russian Academy of Engineering. 
He has worked in academic field for 17 years and industry for over 20 years, including 14 years in Europe and USA and more than 20 years in China. He served as the Director/Chief Engineer of Hybrid Powertrain Technology in Remy International, visiting professor of University of Wisconsin in Madison, USA, and Swiss Federal Institute of Technology in Zurich, Switzerland, Professor and Director of Electric Machine Department in HEIT. He was the inventor of hairpin motor windings , which helped Remy International be listed in NASDAQ; He is the Founder of Jing-Jin Electric (stock # 688280), and the company is a leading tier-1 supplier for electric machines, power electronics converters and e-powertrains for vehicle electrification. 
Prof. Cai is the Director of China EV100 Association, the Fellow of China Electrotechnical Society, and a Deputy group leader of new energy vehicles of 《Green Paper on Technological Innovation in Key Areas of China's Manufacturing Industry》by the Chinese Academy of Engineering.
Challenges and Solutions of Automotive 800VDC Platform and High Speed e-Motor Systems
Clean e-power generation and vehicular electrification are the strategic planning in China.  The carbon emissions and toxic gas emissions are compared between the internal combustion engine vehicles and electric vehicles; The market of new energy vehicles (NEV) and the technology trend of NEV electric drive industry  summarized.  The onboard system voltage of 800VDC raised from below 400VDC facilitates fast battery charging, and the e-motor speed of above 25000rpm from 12000rpm benefits to reduction of  the size and weight of the e-powertrain. However the high voltage and the high switching frequency for controlling the motor challenge many respects of the electric machine systems, including power electronic inverters. The solutions to increase inverter efficiency, power density, temperature tolerance, reliability, and to improve EMC and NVH as well as durability  are given in the presentation. 
Furthermore, some deep researches by my group at university towards upstream of e-powertrain industrial chain are reported  as follows.  A method to raise temperature tolerance of the capacitor film from 105℃ to 125℃ is proposed; The method to reduce parasitic inductance of SiC devices and to improve inverter EMC, the sintered package are introduced to replace bond-wire package, and the required potting resin and plastic sealant as well as sintered materials like silver paste, copper paste are developed by our group. The software algorithm to lower shaft voltage and shaft current is described, through which the bearing ablation due to shaft current  is reduced.  The demands and challenges of e-powertrains for various sub assemblies, motor parts / power electronic components and materials etc., are described, which could be referenced by researchers and engineers.