## 4 AC/DC Converter
### Architectures: Evaluation and Selection
#### 4.4.3 Split Capacitor Topology  
Split Topology with N-Type MOSFETs  
Figure 33 shows simulation results (output power, output voltage, generator efficiency, converter efficiency and complete system efficiency) in function of resistive and duty-cycle, with the same switching frequency as in the previous case.  
In the first case (3 m/s wind velocity), the maximum efficiency of the generator is 26.02% for a 300 \(\Omega\) load and 0.4 duty-cycle. The converter efficiencies are higher than 40%, achieving maximum efficiency of 79.77% with a duty-cycle of 0.4 for a 700 \(\Omega\) resistive load.The whole system maximum efficiency is 14% for a 100 \(\Omega\) load and 0.4 duty-cycle.  
In the second case (10 m/s), the maximum efficiency of the generator is 15.34% for a 1900 \(\Omega\) load and 0.5 duty-cycle. The converter achieves a maximum efficiency of 79.06% with a duty-cycle of 0.5 for a 1100 \(\Omega\) resistive load. The whole system maximum efficiency is 14% for 100 \(\Omega\) load and 0.4 duty-cycle.  
Figure 33: Cont.  
Split Topology with N and P-Type MOSFETs  
Figure 34 shows simulation results (output power, output voltage, generator efficiency, converter efficiency and complete system efficiency) as a function of resistive and duty-cycle, with the same switching frequency as in the previous case.  
In the first case (3 m/s) the maximum efficiency of the generator is 23.78% for a 100 \(\Omega\) load and 0.5 duty-cycle, being similar to 24% achieved with a 27 \(\Omega\) load without any converter or rectifier, i.e., perfect impedance matching. The converter efficiencies are higher than 50%, achieving a maximum efficiency of 82.41% with a duty-cycle of 0.6 for a resistive load of 500 \(\Omega\). The whole system's maximum efficiency is 15.96% for a 100 \(\Omega\) load and 0.5 duty-cycle.  
In the second case (10 m/s wind velocity), the maximum efficiency of the generator is 14.87% for a 200 \(\Omega\) load and 0.4 duty-cycle. The converter achieves a maximum efficiency of 76.66% with a duty-cycle of 0.1 for a 100 \(\Omega\) resistive load. The whole system maximum efficiency is 11% for a 100 \(\Omega\) load and 0.4 duty-cycle.  
To conclude, analyzing all the sweeps of generator efficiency, it can be seen that the output power value at the resistive load is directly related to the best efficiency of the system. In addition, the overall efficiency depends more on the efficiency of the generator than on the efficiency of the converter. Consequently, the generator performance has more weight in the system efficiency.  
Figure 33: Split N converter simulation results. The (**a**,**c**,**e**) figures are with 3 m/s wind velocity and 333 kHz switching frequency. The (**b**,**d**,**f**) figures are with 10 m/s wind velocity and 500 kHz switching frequency. (**a**) Output power (3 m/s, 333 kHz). (**b**) Output power (10 m/s; 500 kHz). (**c**) Output voltage (3 m/s, 333 kHz), Red plane: 3 V as minimum. (**d**) Output voltage (10 m/s, 500 kHz), Red plane: 3 V as minimum. (**e**) Generator + Converter efficiency (3 m/s, 333 kHz). (**f**) Generator + Converter efficiency (10 m/s; 500 kHz).  
Figure 34: Cont.  
Figure 34: Split NP converter simulation results. The (**a**,**c**,**e**) figures are with 3 m/s wind velocity and 200 kHz switching frequency. The (**b**,**d**,**f**) figures are with 10 m/s wind velocity and 500 kHz switching frequency. (**a**) Output power (3 m/s, 200 kHz). (**b**) Output power (10 m/s; 500 kHz). (**c**) Output voltage (3 m/s, 200 kHz), Red plane: 3 V as minimum. (**d**) Output voltage (10 m/s, 500 kHz), Red plane: 3 V as minimum. (**e**) Generator + Converter efficiency (3 m/s, 200 kHz). (**f**) Generator + Converter efficiency (10 m/s; 500 kHz).