## 1 Introduction
CVTs are divided into push-type CVTs that use belts, pull-type CVTs that use chains, and friction-type, tidal type, and E-CVTs that use planetary gears. According to the operating principle of the belt-type CVT, the belt connects the driving pulley and passive pulley, and each pulley is a basic component. Cone-shaped disks are arranged facing each other to change the rotation diameter of the belt between the pulley through tension-compression to realize the shift ratio. Although the belt-type CVT has the advantage of reduced noise, power loss occurs owing to slip between the pulley and the belt. On the other hand, the chain-type CVT has increased power transmission efficiency because slip is reduced by replacing the belt with a chain, and it also responds to a relatively high torque. Its disadvantage is the noise generated by the friction between the pulley and the chain. In the study by [PERSON] [5], a model of a synchronizer-type two-speed transmission was designed using MATLAB/Simulink. The acceleration performance, maximum speed, and efficiency were determined to obtain shift pattern and improve electronic fuel economy by up to 4%, compared with a Nissan Leaf. [PERSON] et al. [6] studied the electronic fuel economy of each driving mode by applying a CVT's 1 st, 2 nd, 3 rd, and 4 th transmissions to 40 kW motorized EV analysis models. For the 4 th transmission model, 4.5% FTP-75 to 8.0% CVT and 5.3% FTP-75 to 10.9% improvements in the New European Driving Cycle were obtained. [PERSON] et al. [7] developed shift control, state of charge (SOC), drive resistance calculation, and vehicle dynamics models using MATLAB/Simulink to select shift pattern at the point with lowest SOC consumption after driving in test mode. [PERSON] et al. [8] developed an EV analysis model using AVL CRUISE software and a two-speed transmission. The comparison of efficiency between a single-reducer electric model with an 80 kW motor and a second-speed transmission EV with a 60 kW motor confirmed the possibility of reducing motor capacity through transmission. [PERSON] and [PERSON] [9] developed a regenerative braking system for an EV that combined a conical cone with a roller and flywheel. A prototype was manufactured, which confirmed increase in energy storage and regenerative braking efficiency. [PERSON] et al. [10] developed an analysis model for Volkswagen's Lupo 3 L and compared the application of an MT and CVT. They confirmed that the CVT provided energy savings of 7% compared with the MT when the final driving ratio was reduced. [PERSON] et al. [11] applied a multistage transmission to an EV. They confirmed an up to 90% improvement in maximum speed, 19.4% acceleration performance, and 11.3% energy savings when a four-speed transmission system was applied to an electric bus. [PERSON] et al. [12] developed vehicle performance and energy efficiency calculation functions using MATLAB/Simulink. They confirmed that the multistage transmission application model could reduce energy consumption by 29% compared with the single transmission application model. Considering the above previous studies, it is important to improve the efficiency of an electric motor by moving the operating point to reflect the actual motor efficiency map in an analysis model. That is, the operating point of the motor changes according to the change in vehicle speed. If the operating point of the motor changes, it is highly likely that the efficiency of the motor does not operate at the optimal point. Therefore, if the CVT is used, we can set it to operate in the section where the operating efficiency of the motor is maximized. Of course, all transmissions generate a delay according to operation, and how quickly they respond to it is a factor that has a major impact on fuel economy. When the motor passes through a certain torque range and proceeds at high RPM, a certain output range proceeds, which shows a tendency for efficiency to decrease as the motor goes to high RPM due to the characteristics of the motor.