## 5 Experimental Results
### Buck Topology  
Figure 9 shows the power efficiency of the buck topology in the CV and CC modes. If the power efficiency difference \(P_{Diff}\) is positive (+), it means efficiency improvement; if it is negative (-), it indicates an efficiency decline. The power efficiency improves in every condition from 10-80 W because of the removal of D\({}_{2}\) in the switch-off section in the CV and CC modes. \(P_{Diff}\) increases as the switch-off section becomes longer, i.e., when there is an increase in the duty ratio. In the same duty ratio condition, \(P_{Diff}\) decreases with an increase in the input voltage and output current. The improvement effect is large in the low-power region. The proposed converter can achieve a greater efficiency improvement effect in a region where the voltage conversion is large, and the output current is low.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**V\({}_{var}\)**} & \multirow{2}{*}{**Device**} & \multicolumn{6}{c}{**CV**} & \multicolumn{6}{c}{**CC**} \\ \cline{3-14}  & & \multicolumn{3}{c}{**Conventional (V\({}_{max}\))**} & \multicolumn{3}{c}{**Proposed (V\({}_{max}\))**} & \multicolumn{3}{c}{**Conventional (V\({}_{max}\))**} & \multicolumn{3}{c}{**Proposed (V\({}_{max}\))**} \\ \cline{3-14}  & & \multicolumn{3}{c}{**Buck**} & \multicolumn{3}{c}{**Buck-Boost**} & \multicolumn{3}{c}{**Buck-Boost**} & \multicolumn{3}{c}{**Buck-Boost**} & \multicolumn{3}{c}{**Buck**} & \multicolumn{3}{c}{**Buck-Boost**} & \multicolumn{3}{c}{**Buck**} & \multicolumn{3}{c}{**Buck-Boost**} \\ \cline{3-14}  & & & \multicolumn{3}{c}{**Step-Step-Up**} & \multicolumn{1}{c}{**Step-Down Up**} & \multicolumn{1}{c}{**Buck**} & \multicolumn{1}{c}{**Step-Down Up**} & \multicolumn{1}{c}{**Buck**} & \multicolumn{1}{c}{**Boot**} & \multicolumn{1}{c}{**Step-Down Up**} & \multicolumn{1}{c}{**Step-Down Up**} & \multicolumn{1}{c}{**Step-Down Up**} & \multicolumn{1}{c}{**Step-Down Up**} & \multicolumn{1}{c}{**Step-Down Up**} \\ \hline \multirow{4}{*}{25\%} & S\({}_{1}\) & 53.3 & - & 53.3 & 32.0 & 53.3 & - & 53.3 & 32.0 & 80.0 & - & 80.0 & 80.0 & 80.0 & - & 80.0 & 80.0 \\  & S\({}_{2}\) & - & 41.3 & 46.0 & 45.5 & - & 41.6 & 47.5 & 46.8 & - & 104.5 & 67.2 & 114.8 & - & 105.2 & 68.9 & 116.9 \\  & D\({}_{1}\) & 53.3 & - & 53.3 & 32.0 & 53.3 & - & 100.8 & 78.8 & 80.0 & - & 80.0 & 80.0 & 80.0 & - & 148.9 & 196.9 \\  & D\({}_{2}\) & - & 41.3 & 46.0 & 45.5 & - & 41.6 & - & 104.5 & 67.2 & 114.8 & - & 105.2 & - & 105.2 & - \\ \hline \multirow{4}{*}{33\%} & S\({}_{1}\) & 60.0 & - & 60.0 & 30.0 & 60.0 & - & 60.0 & 30.0 & 80.0 & - & 80.0 & 80.0 & - & 80.0 & 80.0 \\  & S\({}_{2}\) & - & 41.3 & 45.9 & 44.9 & - & 41.7 & 47.5 & 46.3 & - & 111.9 & 59.0 & 121.0 & -Figure 8: Waveforms of PWM, inductor current \(I_{L}\), gate-source voltage \(V_{GS}\), and output voltage \(V_{o}\): PWM of (**a**) buck; (**b**) boost; (**c**) buck-boost step-down; (**d**) buck-boost step-up; \(I_{L},V_{GS},V_{o}\) of (**e**) buck (at d = 0.667; \(I_{L}\) = 1.5 A); (**f**) boost at d = 0.250, \(I_{L}\) = 0.75 A); (**g**) buck-boost step-down (at d = 0.400, \(I_{L}\) = 1.5 A); and (**h**) buck-boost step-up (at d = 0.571, \(I_{L}\) = 0.75 A).  
Figure 9: Power efficiency comparison of the buck topology: (**a**) CV mode; (**b**) CC mode.