# Power-Split Hybrid Train Configuration Design Based on a Single-Row Star Row
## 1 Introduction  
In 2017, in Europe, the transportation sector contributed 27.9% of greenhouse gas (GHG) emissions and 30.8% of ultimate energy consumption [1]. Rail freight is more energy-efficient and emits 3.5 times fewer greenhouse gases than automobile freight [2]. Rail transportation is still quite competitive according to studies on hybrid diesel engines used for rail freight propulsion [3]. Many nations have suggested supporting the creation of cutting-edge rail transportation technologies. Hybrid trains were developed to satisfy transportation needs while considering fuel consumption and emissions, which served as a response to the government's push for innovation-driven, green developments and the rising awareness of environmental concerns. However, little has been carried out to evaluate the operational performance of replacing diesel trains with hybrid trains on the same track. Fuel usage and power output are significantly impacted by the train design. The hybrid train power system configuration was thus improved to further enhance the economy and dynamics of hybrid trains. The mechanical construction of the hybrid system connects the engine to the motor, and a power-coupling device can be employed to boost the overall vehicle power output. The split hybrid power system can continuously optimize the engine speed and torque over a wide range of vehicle speeds because it uses a planetary gear arrangement to decouple the engine from the wheels. The public praised the Prius for its exceptional fuel-saving capabilities when it was introduced for mass production in Japan in 1997 [4; 5]. [PERSON] [6] proposed the design of a series/parallel hybrid electric power system to increase safety and optimize the fuel economy by controlling the engine working points. [PERSON] [7] presented a novel composite power-split hybrid system based on two planetary gear sets for commercial vehicles. Six operating modes were analyzed by means of a simplified combined lever diagram and power performance and economic performance simulations were carried out, and the results show that the proposed configuration has a significant fuel-saving performance. [PERSON] [8] proposed a powertrain configuration scheme design method based on hierarchical topological graph theory. The kinematic and dynamical modeling of the powertrain, classification of configuration modes, and synthesis of scenarios for power-split hybrid electric vehicles (PS-HEVs) were carried out. The powertrain configuration of PSHEVs is the basis of energy management, which determines the operating mode, control algorithm selection, and optimization potential, and directly affects the vehicle's comprehensive performance [9]. Thirty-two novel hybrid transmissions consisting of a Ravigneaux gear train and a single planetary gear train were synthesized using a creative design methodology based on graph theory and the lever analogy method. The design process commences by identifying an existing transmission configuration that meets all of the design requirements [10]. In order to raise the transmission ratio of the train, [PERSON] [11] proposed an innovative design of a half-toroidal planetary traction train (half-toroidal PT) with a continuously variable planetary ratio. [PERSON] [12] proposed a new matrix approach for identifying the basic functional parameters underlying the model from the constructive layout of the transmission. Using a globally optimal control method based on the dynamic programming (DP) technique, [PERSON] [13] simulated the best economic scenario and the best power performance of the configuration scheme generated for their proposed single-row star-row split hybrid powertrain configuration design scheme. [PERSON] [14] established a transient optimal control to regulate the power flow of a power-split hybrid vehicle with a dual planetary gear set as the focus.