###### Abstract
To compensate for this, a permanent magnet TCV has been studied so that it does not lose its function even if the power is cut off during the TCV operation period, as shown in Figure 2b. The auto-hold function of the car was able to maintain the braking function by the permanent magnet even if the power is cut off after the TCV operation. After initial power is applied and the valve is actuated, even if the power is cut off during the maintenance period, the permanent magnet can maintain its function, reducing power consumption as no additional power is supplied. In addition, since the power is cut off during the auto-hold period, it has the advantage of reducing the heat generation of the magnetic coil and minimizing the shortened lifespan due to the internal temperature rise. Solenoid valves studied so far have focused on the magnitude and characteristics of electromagnetic force. In addition, research was conducted to confirm the electromagnetic characteristics according to the material properties and specifications of the magnetic material, and to suggest the optimal solenoid valve design method. [PERSON] et al. conducted an optimal design study to predict and experimentally verify the electromagnetic force of a solenoid valve for a hydrogen-fueled electric vehicle through electromagnetic field analysis [24]. [PERSON], [PERSON], and [PERSON] studied the structure of a solenoid magnetic material and the change in electromagnetic force according to the change of the air gap [25; 26; 27]. [PERSON] and [PERSON] studied the optimal solenoid valve design by experimentally analyzing the B-H curves of various soft materials and taking into account the change in the electromagnetic force according to the shape [28; 29]. [PERSON] et al. used FEA to study the effect of magnetic cross-sectional area and magnet coil specifications of solenoid valves on static electromagnetic properties. He also simulated the dynamic process of a solenoid valve to quantitatively understand the effect of solenoid valve parameters on the dynamic response characteristics [30]. However, previous studies have studied the properties of electromagnetic force through FE simulation using the structure of the solenoid valve and the shape and material properties of magnetic materials. The product was manufacturedbased on FE simulation and verified through test evaluation. Through this study, a solenoid valve applied with a permanent magnet was studied through FE simulation. The magnetic force, electromagnetic force, and their resultant force were studied and evaluated according to the polarity direction and specification of the permanent magnet. A permanent magnet TCV was manufactured and an electromagnetic force test was conducted to compare and evaluate it with the FE simulation result. In order to check whether the braking function is maintained by the permanent magnet even when the current is cut in the auto-hold function of the TCV, a test evaluation was conducted under actual vehicle conditions. Also, by using a permanent magnet, it was possible to lower the initial current value for the TCV to drive. Therefore, it was possible to develop a permanent magnet TCV that can minimize the unnecessary power consumption of electric vehicle batteries.