Design and Development of 6-Ph IGBT Based Liquid Cooled Traction Electrics for E-Bus Application

Direct drive technology based drive trains are preferred for heavy and commercial electric vehicles due to improved efficiency, less maintenance and availability (all due to elimination of gear box) with little sacrifice on weight and size. This paper presents the design, development, testing and certification of the 6-Phase insulated gate bi-polar transistor (IGBT) based liquid cooled traction electrics for E-buses. DSP & FPGA based control hardware is designed and developed as a sub-system to the traction electrics. In this paper the sensored vector control algorithm and maximum torque per ampere (MTPA) with field weakening operation of traction drive is presented. The paper also presents development activities, testing and certification results. The traction electric is designed to handle peak power of 360 kVA. The developed traction electric is tested and certified on a 145 kW Interior permanent magnet synchronous machine (IPMSM) as per the AIS-041:2015 standard. This standard defines the peak and continuous power capability of the drive train under test. The developed traction electric is such that it is suitable for both induction motor and permanent magnet motor technologies.