Dual Motor Single Shaft Powertrain Concept

Most of the modern electric vehicles (EV's) are not equipped with additional transmission that allows to set a different value of mechanical ratio. The redundancy of multispeed transmission application necessity is a result of very good electric motor (EM) torque speed characteristic. On the other hands, the changeable mechanical ratio allows to adjust in the best way the operational parameters of EM to momentary load on the vehicle wheels. This feature, in consequence, results in total drive efficiency increasing, so in the same time the energy consumption decreasing. The use of multispeed transmission in pure electric drive required its automated operation. There are many kinds of mechanical transmission that may be adopted to electric drive. One of them is Automated Manual Transmission (AMT). The advantage of mentioned transmission is relatively simple construction and way of operation as well as its lower price compared to other transmissions. However, its disadvantage is the EM interrupted operation during gear shifting. This disadvantage can be removed thanks to the proper drive train structure. One of them seems to be dual motor - single shaft drive powertrain. This structure consists of two electric motors and one multispeed transmission. One of EMs is connected to the multispeed transmission input shaft while the second is connected to the multispeed transmission output shaft and then to the final drive. This way of electric motor arrangement in electric drive structure brings together the benefits of multispeed transmission application and the possibility of vehicle propelling during gear shifting. The smooth and seamless operation of electric powertrain during gear shifting requires a proper way of both EMs control. The control strategy for gear shifting will be defined and verified using the computer simulations.