# Output Filter Design for a Novel Dual-Input PV-Wind Power Converter by Energy Balance Principle
## 5 Experimental Results  
To verify the correctness of the theoretical analysis in this paper, a 1-kW prototype with the specifications summarized in Table 2 is built. The output inductor \(L_{o}\) is designed according to Section 4, which ensures CCM operation while output power is greater than 500 W. In Figure 7, the output power \(P_{o}\) is equal to 500 W. It can be seen that the inductor current \(i_{Lo}\) is twice the switching frequency and in BCM. This experimental measurement of \(i_{Lo}\) and inductor voltage \(v_{Lo}\) are identical to the conceptual waveforms depicted in Figure 6. Output power can be increased by enlarging the duty ratios of active switches. At 1-kW output, Figure 8 shows that the control signals \(v_{sw,pv}\) and \(v_{sw,wind}\) are still in an interleaved pattern but with larger duty ratio than that in Figure 7. In addition, the inductor current \(i_{Lo}\) is, indeed, in CCM. To examine the voltage and current stresses of the active switch, Figure 9 shows the practical voltage \(v_{ds,wind}\) and current \(i_{ds,wind}\) at full load, while \(v_{ds,pv}\) and \(i_{ds,pv}\) are shown in Figure 10. The \(v_{ds,wind}\) and \(i_{ds,wind}\) stand for the voltage and current of the active switches \(SW_{1,wind}\) and \(SW_{2,wind}\), as \(v_{ds,pv}\) and \(i_{ds,pv}\) do for \(SW_{1,pv}\) and \(SW_{2,pv}\). Figure 11 indicates that the output voltage can be kept at 400 V with the designed inductance, even if one of the renewable power sources shuts down. The DIPWC is able to accomplish a high conversion efficiency. Figure 12 depicts the measured efficiency from light load to full load, in which the peak efficiency is up to 95.4%. The practical measurement of the MPPT result at full load is shown in Figure 13. After MPPT, Figure 14 shows the steady-state output voltage of the PV module, \(v_{pv}\), from which it can be seen that the output voltage fluctuates around a constant. In addition, Figure 15 is the picture of the DIPWC setup. \begin{table}
\begin{tabular}{c c} \hline
**Symbols** & **Values \& Types** \\ \hline \(v_{wind}\) (wind-turbine voltage) & 120 V \\ \(v_{pv}\) (PV voltage) & 80 V \\ \(V_{Co}\) (output voltage) & 400 V \\ \(P_{o}\) (output power) & 1 kW \\ \(f_{s}\) (switching frequency) & 40 kHz \\ \(L_{m,wind}\) (magnetizing inductance) & 1.09 mH \\ \(L_{m,pv}\) (magnetizing inductance) & 1 mH \\ \(L_{k,wind}\) (leakage inductance) & 4.2 mH \\ \(L_{k,pv}\) (leakage inductance) & 4 mH \\ \(L_{o}\) (output inductance) & 584 mH \\ \(n_{wind}\) (turns ratio of \(T_{1}\)) & 2.12 \\ \(n_{pv}\) (turns ratio of \(T_{2}\)) & 2 \\ \(C_{1,wind}\) and \(C_{2,wind}\) (capacitors) & 47 mF \\ \(C_{1,pv}\) and \(C_{2,pv}\) (capacitors) & 33 mF \\ \(C_{o}\) (output capacitor) & 220 mF \\ \(SW_{1,wind}\) and \(SW_{2,wind}\) (switches) & IXFH120N20P \\ \(SW_{1,pv}\) and \(SW_{2,pv}\) (switches) & IXFH120N15P \\ \hline \end{tabular}
\end{table} 
Table 2: The specifications of the DIPWC. Figure 8: Measured waveforms while the DIPWC is operated at full load (\(\
u_{syn,wind}\): 10 V/div, \(\
u_{slope}\): 10 V/div, \(\
u_{Lo}\): 250 V/div, \(\dot{\
u}_{Lo}\): 2 A/div, time: 5 \(\upmu\)s/div). Figure 9: Measured waveforms of active switches at wind-turbine input port while the output power is 1 kW (\(\
u_{syn,wind}\): 10 V/div, \(\
u_{slope}\): 10 V/div, \(\
u_{d,wind}\): 100 V/div, \(\dot{\mu}_{d,wind}\): 20 A/div, time: 5 \(\upmu\)s/div). Figure 11: Measured waveforms to illustrate the transient response of the DIPWC (\(v_{\text{suz,wind}}\): 10 V/div, \(v_{\text{suz,pe}}\): 10 V/div, \(v_{\text{Lo}}\): 200 V/div, \(i_{\text{Lo}}\): 2 A/div, time: 5 u/div). Figure 12: The measured efficiency from light load to full load. Figure 10: Measured waveforms of active switches at the PV input port while the output power is 1 kW (\(v_{\text{suz,wind}}\): 10 V/div, \(v_{\text{suz,pe}}\): 10 V/div, \(v_{\text{suz,pe}}\): 50 V/div, \(i_{\text{ds,pe}}\): 20 A/div, time: 5 u/div). Figure 14: Output voltage of the PV module after MPPT and in steady state (\(v_{pv}\): 50 V/div, time: 2 s/div).