# Design of a Solenoid Actuator for a Cylinder Valve in a Fuel Cell Vehicle
## 6 Conclusions  
A solenoid actuator was designed for hydrogen storage cylinder valves used in FCV, and its performance was evaluated. For the design of the solenoid actuator with reliability of the motions under ultra-high pressure, we must consider many factor such as coil resistance, temperature rise, magnetic flux density, magnetomotive force, attraction force at saturation temperature, etc. The optimal design of an actuator based on electromagnetic and heat transfer theories so that it satisfies the required attraction force at the saturation temperature was designed analytically. Heat transfer analysis was conducted to check the validity of the calculated saturation temperature, and electromagnetic field analysis was done to evaluate the attractive force at this temperature. To validate the results of the analyses, a prototype was fabricated, and the attractive force was measured. \begin{table}
\begin{tabular}{c|c c c|c c c|c c} \hline  & \multicolumn{5}{c|}{**Duty Ratio = 100\%**} & \multicolumn{3}{c}{**Duty Ratio = 40\%, 25 kHz**} \\ \cline{2-10}
**Distance between** & **Maxwell** & **Experiment** & **Error** & **Maxwell** & **Experiment** & **Error** & **Maxwell** & **Experiment** & **Error** \\
**Magnetic Poles** & **(25 °C)** & **(25 °C)** & **(79.9 °C)** & **(77.7 °C)** & **Error** & **(79.9 °C)** & **(77.7 °C)** & **Error** \\ \hline
0.1 mm & 53.33 & 50.09 N & 3.21 N & 51.74 N & 48.53 N & 3.21 N & 32.03 N & 29.25 N & 2.78 N \\
0.2 mm & 48.46 N & 44.95 N & 3.51 N & 46.52 N & 43.0 N & 3.22 N & 22.29 N & 19.20 N & 3.09 N \\
0.3 mm & 44.1 N & 40.44 N & 3.66 N & 41.2 N & 37.62 N & 3.58 N & 16.27 N & 12.42 N & 3.85 N \\
0.4 mm & 39.94 N & 36.23 N & 3.71 N & 36.43 N & 33.01 N & 3.42 N & 12.47 N & 8.68 N & 3.79 N \\
0.5 mm & 36.4 N & 32.71 N & 3.69 N & 32.4 N & 28.80 N & 3.60 N & 9.79 N & 6.13 N & 3.65 N \\
0.6 mm & 33.27 N & 29.61 N & 3.66 N & 29.08 N & 25.71 N & 3.37 N & 7.97 N & 4.54 N & 3.43 N \\
0.7 mm & 34.06 N & 26.91 N & 3.55 N & 26.28 N & 23.32 N & 2.96 N & 6.60 N & 3.71 N & 2.89 N \\
0.8 mm & 28 N & 24.48 N & 3.52 N & 23.88 N & 20.90 N & 2.98 N & 5.99 N & 2.82 N & 2.77 N \\
0.9 mm & 25.84 N & 22.28 N & 3.56 N & 21.81 N & 18.21 N & 3.60 N & 4.87 N & 2.54 N & 2.33 N \\ \hline \end{tabular}
\end{table} 
Table 5: Attraction force with respects to distance between magnetic poles and duty ratio. Figure 15: Comparison of attraction force between analysis and experiment: (**a**) Ambient temperature, duty ratio = 100%; (**b**) Saturation temperature, duty ratio = 100%; (**c**) Saturation temperature, duty ratio = 40%. The confirmed results are as follows:  
1. The structure of double plunger type solenoid actuator is introduced to obtain worked in environment of cylinder valve for FCV such as ultra-high pressure. 2. In this study we derived the temperature rise formula of solenoid actuator based on heat dissipation coefficient and heat dissipation area on a coil. Formula have significant effects on the prediction for temperature increase of coil and attraction force of solenoid actuator at saturation temperature. 3. The finite element analysis was used to simulate the attraction force of the solenoid actuator. The results of the comparison indicated that coil temperature and duty ratio of input voltage were crucial to the solenoid actuator attraction force. Therefore, coil temperature is one of the most important design parameters of solenoid actuators for cylinder valves. 4. The optimal design and finite element analysis procedure for minimizing power consumption of PWM control solenoid actuators was proposed. The results of the finite element analysis and thermal and electromagnetic experiments indicate good matches. This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (2013H1 BSA2032233). [PERSON] designed and performed the experiments and analysis, and wrote the paper; [PERSON] and [PERSON] built up the research project and consulted with the research process.