Abstract Engine torque fluctuation is a great threat to vehicle comfort and durability. Former researches tried to solve this problem by introducing active damping system, which means the motor is controlled to produce torque ripple with just the opposite phase to that of the engine. By this means, the torque fluctuation produced by the motor and the engine can be reduced. In this paper, a new method is raised. An attempt is proposed by changing the traditional structure of the motor, making it produce ripple torque by itself instead of controlling the motor. In this way a special used ISG (Integrated Starter Generator) motor for HEV (Hybrid Electrical Vehicles) is made to achieve active damping. In order to study the possibility , a simulation, which focus on the motor instead of the whole system, is developed and series-parallel configuration is used in this simulation. As for the motor that used in this paper, four kinds of motors have been investigated and compared. Among which, SRM (Switched Reluctance Motor) has larger torque ripple, while PMSM (permanent magnet synchronous motor) has relatively high efficiency and is widely used. Hence, these two kinds of motors are simulated. And results show that simply reducing the number of magnetic poles is hard to match the engine’s torque ripple due to its higher frequency of fluctuation. But we can’t deny the possibility of other ways and more investigations and researches need to be done. Introduction With the need of saving energy and decreasing the amount of pollution is increasing, the question whether we should use EVs (Electrical Vehicles) as an alternative or stick to finding new ways to reduce the fuel consumption of traditional vehicles which use ICE (Internal Combustion Engine) is raised. EVs’ fuel consumption is almost zero while driving and produce few pollutions but they can’ t meet the need of long distance driving while traditional vehicles have long driving distance duel to high energy density of liquid fuels but their fuel consumption is higher than EV and produce more pollution. Therefore, using HEVs which combine the advantages of the EVs and traditional vehicles is a feasible way to meet the need.Under this background, HEVs have been developed and researched for decades. And products like Toyota's Prius and BYD’s Qin, Lexus’ ES300h, Honda’s Fit Hybrid are produced and sold. But even after many years’ researches, HEVs still have some problems to be solved like the comfort and durability of HEVs. The comfort and durability are important to measure a vehicle’s performance especially for Luxury cars. One of the causes of low comfort and durability is the torque fluctuation produced by the engine due to piston’s reciprocating working. The ripple torque will cause the torsional vibration and in traditional cars, torsional damper is used to solve this problem. But the characters of comfort and durability of HEVs are different from traditional vehicles cause the changes in structure of driveline. Even if the complexity of the driveline is increased but it also provides the possibility by using the motor near the engine to reduce the ripple torque. The whole system used to achieve this function is called active damping system. The basic idea of this system can be described in figure 1 Figure 1. Active damping control diagram Several researches of this system have been published. Honda's Kenji NAKANO and Shinobu OCHIAI proposed a motor-assisted system called IMA (Integrated Motor Assist) System, which was applied to Honda Insight models [ 5]. One of the functions of the system is to use the motor torque to compensate the engine torque ripple to Simulations on Special Structure ISG Motor Used for Hybrid Electrical Vehicles Aimed at Active Damping2017-01-1123 Published 03/28/2017 Jinyu Zhang, Yaodong Hu, Fuyuan Yang, and Chao Xu Tsinghua University CITATION: Zhang, J., Hu, Y ., Yang, F., and Xu, C., "Simulations on Special Structure ISG