## 4 Experimental Results  
To verify the proposed ZVS ITLDC, a 1.5 kW prototype ITLDC with ACACs is utilized with the specifications shown in Table 1. When the proposed ITLDC is used to charge EVs, the ACACs mainly play a role in the constant-voltage charging stage. During the constant-voltage charging stage, the charging current changes with charging time and the charging current is relatively small. Then, the ITLDC cannot realize natural ZVS soft switching during the constant-voltage charging stage; thus, the ACACs will work to realize ZVS soft switching. In this experiment, the input voltage is 400 V, which is powered by a programmable DC voltage source. The variable resistor with 80 \(\Omega\) maximum resistance is used as a load and the output voltage is controlled to 150 V. The snubber capacitors \(C_{\rm s}\) are added in parallel with the main switches, and the equivalent parallel capacitors \(C_{\rm 1}\)\(\sim\)\(C_{\rm 4}\) are increased; thus, the main switches are turned off at quasi-zero-voltage condition. A photograph of the experimental platform is shown in Figure 8. \begin{table}
\begin{tabular}{l l} \hline \hline
**Items** & **Value** \\ \hline Input voltage \(V_{\rm in}\) & 400 V \\ \hline Output voltage \(V_{\rm out}\) & 150 V \\ \hline Maximum output current \(I_{\rm o}\) & 10 A \\ \hline Main switches & IPW65R041 CFD \\ \hline Auxiliary switches & IXFH22N65X2 \\ \hline Diode D\({}_{\rm B1}\), D\({}_{\rm B2}\) & DSEI60-06A \\ \hline Switching frequency \(f\) & 40 kHz \\ \hline Transformer ratio \(n\) & 1:1 \\ \hline Magnetizing inductances \(L_{\rm m}\) & 1.22 mH \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The specifications of the prototype ITLDC. The main waveforms measured are shown in Figure 9, where \(V_{\rm{DS1}}\) is the drain-source voltage of the main switch S1, \(G_{\rm{S1}}\) is the drive of S1, \(i_{\rm{o}}\) is the output current, \(i_{\rm{Lr}}\) is the current of the primary winding of the transformer, \(V_{\rm{CA1}}\) is the voltage of the auxiliary capacitance \(C_{\rm{A1}}\), \(G_{\rm{S2}}\) is the drive of S2, \(G_{\rm{SA1}}\) is the drive of S\({}_{\rm{A1}}\), and \(i_{\rm{A1}}\) is the auxiliary current flowing through \(L_{\rm{A1}}\). The turn-on process of the main switch S1 without ACACs is shown in Figure 9a,b. As shown in Figure 9a, the output current \(i_{\rm{o}}\) is 2 A, and before S1 is turned on, the voltage \(V_{\rm{DS1}}\) is discharged from 200 V to 150 V. As shown in Figure 9b, the output current \(i_{\rm{o}}\) is 10 A, and before S1 is turned on, the voltage \(V_{\rm{DS1}}\) is discharged from 200 V to 40 V firstly; however, \(V_{\rm{DS1}}\) increases to 160 V quickly. In Figure 9a,b, the zero-voltage turn-on condition of the main switch S1 is unrealized. However, as shown in Figure 9c, the main switch S1 is turned off at quasi-zero-voltage condition. This is because the equivalent parallel capacitors \(C_{\rm{1}}\)\(\sim\)\(C_{\rm{4}}\) limit the rising slope of the voltage across the main switches. In this experiment, 1000 pF snubber capacitors are added in parallel with the main switches and the time-related effective output capacitance of the main switch is 1485 pF (documented in the data sheet); thus, the snubber capacitors \(C_{\rm{s}}\) of the main switches are equal to 2485 pF. \begin{table}
\begin{tabular}{l c} \hline
**Items** & **Value** \\ \hline DC-blocking capacitor \(C_{\rm{b}}\) & 40 \(\mu\)F \\ \hline Leakage inductance \(L_{\rm{r}}\) & 1.8 \(\mu\)H \\ \hline Added snubber capacitor & 1000 pF \\ \hline Dead time \(t_{\rm{dead}}\) & 0.35 \(\mu\)s \\ \hline Filter inductance \(L_{\rm{o}}\) & 0.5 mH \\ \hline Auxiliary inductor \(L_{\rm{A}}\) & 18 \(\mu\)H \\ \hline Auxiliary capacitor \(C_{\rm{A}}\) & 9.4 \(\mu\)F \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
Figure 8: A photograph of the experimental platform. In fact, according to (6), to realize natural ZVS, the output current \(i_{0}\) should be larger than 38.9 A. When the output current is not large enough to realize natural ZVS, the proposed ACACs can be used to realize ZVS.