## 1 Introduction
By estimating the adhesion conditions of road surface, the proposed torque vectoring algorithm improves the energy efficiency of the powertrain while ensuring the stability of vehicle handling. Compared with the LQR RU torque vector algorithm, the motor efficiency can be increased by about 9.6%, and the motor energy consumption can be reduced by up to 35.1%. [PERSON] et al. [11] proposed a torque distribution nonlinear controller based on model predictive control theory to adjust the front wheel steering angle and additional yaw moment for the purpose of reducing energy consumption and ensuring safety. Simulation carried out through AMSim shows that the proposed torque distribution strategy under two-lane change and straight-line acceleration operation improves energy saving by 4.50% and 0.80%, respectively, while the power loss does not exceed 0.08%. Although the above method can reduce the power loss, the undesirably complicated control algorithms and calculations are required in the case of operating multiple motors independently mounted on individual wheel. Recently, various types of TVD were made public in the form of patents by some automobile manufactures and companies [12; 13; 14]. In addition, several new TVDs with various types of activating torque vectoring were presented as well as analyzed as found in the following research works. Reference [15] reveals two new types of conventional level- gear TVD. One is coupled with a gearset activated by superposition clutches and the other is assembled with a gearset actuated by stationary clutches. Reference [16] reveals a new design of TVD, Rav-TVD, which consists of a Ravigneaux gearset with the small sun gear and the carrier, respectively, connected to brakes. Thereby, different torque vector effects can be controlled through the engagement of the brakes. Reference [17] comes out with a novel TVD, consisting of a planetary gear train of the Ravigneaux type as the function of differential and final drive, and a superimposing unit to fulfill the torque vectoring function using a small electric machine. Reference [18] proposes an innovative rear TVD,called torque vectoring electric rear axle drive (TVeRAD). The carrier of each planetary gear is linked to the halfshaft of each wheel. The main traction motor is interconnected between two planetary gearsets and drives the sun gears of the gearsets, while a compact torque vectoring motor is geared directly to a balance shaft, placed between the two ring gears. A developed control system proves to be capable of maximizing vehicle longitudinal performance as well as enhancing the handling characteristic of the vehicle using TVeRAD. The proposed differential in this study, termed as motor-modulated torque vectoring differential, or briefly, MLTD, is a kind of TVD whose lateral torque vectoring function is actuated by an auxiliary motor, named the distributing motor (DM). Compared with the conventional torque vectoring differentials activated by frictional means, such as mechanical clutches or electromagnetic clutches, the MLTD possesses the advantages of faster response, easier control, safer maneuverability, etc. Moreover, the energy saving gained from utilizing the DM, rather than the conventional clutches causing undesired energy consumption, can bring forth a longer driving range. The architecture and kinematic characteristics of MLTD are explained in the beginning. Then, a steady-state vehicle dynamic model is constructed to evaluate the corning performance using lateral torque vectoring technology. It follows that a conceptual-design case of the MLTD applied to a front-wheel-drive electric vehicle is conducted to assess its feasibility based on driving and corning performance. Furthermore, one way to enhance energy efficiency of EV by reducing rolling resistance of tires, e.g., cutting down vehicle mass or redesigning a tire with lower coefficient of rolling resistance, may come along with an undesirable problem that cornering performance and safe handling would be worsened.