# A Novel Optimal Control Strategy of Four Drive Motors for an Electric Vehicle
## 1 Introduction
Using system simulation results presented in a multi-dimensional lookup table format and through program coding and direct downloading to the control unit, the ECMS design concept can be applied to energy management strategies and electric/power systems, further saving the power consumption of hybrid motorcycles and offering more rigorous academic analysis. The control objective can target energy efficiency and braking energy recovery performance, such as front and rear wheel braking torque distribution and hydraulic wheel-in motor braking energy recovery [17]. In the study of plug-in hybrid vehicles, the optimization goal is to minimize the vehicle's instantaneous comprehensive operating costs. This involves integrating heterogeneous energy costs such as instantaneous engine fuel costs, battery electricity costs, and even battery aging costs into the objective function. An energy management control strategy is formulated to address the optimal gear-shifting problem and the optimal torque distribution problem [18]. The ECMS can convert the electrical energy of the battery into an equivalent amount of fuel consumption by introducing an Equivalent Factor for hybrid vehicles and minimizing the total fuel consumption at each moment. This total fuel consumption is the sum of the actual fuel consumption of the internal combustion engine and the weighted equivalent fuel consumption of the electric motor [19]. Therefore, the ECMS method is based on the principle that for the cost of energy distribution, the stored electrical energy is equivalent to consuming (or saving) a certain amount of fuel. Although this cost cannot be directly known because it depends on future vehicle behavior, it has been proven to be broadly related to driving conditions [20]. Additionally, the dual motor drive braking energy recovery technology first optimizes the charging efficiency, establishing the optimal distribution strategy of the front and rear motor braking torques under different driving modes, and verifies methods comparing rules based on the model predictive control using the hardware-in-the-loop (HIL) platform for verification [21]. Energy management is a crucial control technology for multiple energy sources. To fully utilize the energy-saving potential of four-wheel drive (4 WD) electric vehicles, energy management strategies need to consider various constraints, such as the powertrain, driving conditions, and vehicle operational status, and balance the control's economic and real-time aspects [22]. In 4 WD electric vehicles, the power output of the front and rear motors directly affects the vehicle's economy under different driving and braking conditions. ECMS implements various solutions for controlling the energy distribution of the front and rear motors under different driving conditions, with the primary goal of optimizing economy [23]. From the literature review, it can be concluded that the study mainly focuses on any type of 4 WD electric vehicle architecture. The purpose of studying its performance is to optimize key aspects of HEV functionality, such as fuel reduction techniques. Energy management and power optimization are other important areas of focus [24]. In this study, actual vehicle controllers are applied, considering the improvement of computational efficiency and quantitative control analysis, adopting research and discussion on the four-wheel average torque mode and ECMS, and designing for four-wheel drive motor vehicles. In the ECMS method, a cost function is set, which here refers to the minimum total consumption of the four-wheel drive motors under test conditions; penalties are also set as well as the relationship between optimal search inputs and outputs [25]. The multi-power coupling system makes the energy management of 4 WD electric vehicles relatively complex. To enhance vehicle economy and adaptability to driving modes, optimizing the energy management system is a critical factor [26].