# A New SEPIC-Based DC-DC Converter with Coupled Inductors Suitable for High Step-Up Applications
## 6 Applicability of the Proposed SEPIC Converter in a PV System
### Simulation Results of the PV System Using the Proposed SEPIC Converter  
To prove the utility of the proposed SEPIC-based converter in the PV system, a simulation that follows the scenario below was performed. All the changes encountered were step changes. Figure 23: The experimental efficiency against the output power. Figure 24: The block diagram of the PV system. at start-up \(T_{1}\) = 0 ms, the irradiance was set to \(G_{1}\) = 1000 W/m\({}^{2}\), and the load resistance was \(R\) = 450 \(\Omega\); - at \(T_{2}\) = 20 ms, the load resistance suffered a change to \(R\) = 325 \(\Omega\); - at \(T_{3}\) = 28 ms, the load resistance was changed to \(R\) = 350 \(\Omega\); - at \(T_{4}\) = 37 ms, the load resistance was modified to \(R\) = 360 \(\Omega\); - at \(T_{5}\) = 68 ms, the irradiance was suddenly modified from \(G_{1}\) = 1000 W/m\({}^{2}\) to \(G_{2}\) = 800 W/m\({}^{2}\); - at \(T_{6}\) = 98 ms, the irradiance was set back to \(G_{3}\) = 1000 W/m\({}^{2}\); - at \(T_{7}\) = 133 ms, the output resistance was changed to \(R\) = 460 \(\Omega\); - at \(T_{8}\) = 135 ms, the irradiance was set from \(G_{3}\) = 1000 W/m\({}^{2}\) to \(G_{4}\) = 900 W/m\({}^{2}\); - at \(T_{9}\) = 136 ms, the output resistance was changed back \(R\) = 360 \(\Omega\); - the last change was at \(T_{10}\) = 165 ms, when the irradiance was modified from \(G_{4}\) = 900 W/m\({}^{2}\) to \(G_{5}\) = 1000 W/m\({}^{2}\). The simulation time was 250 ms. The simulation step chosen was 20 ns, and the results were displayed each one hundred simulation steps. In Figure 25, the input (red) and the output (blue) power against time are represented. With these characteristics, the changings according to the scenario can be easily identified, and it can be remarked that the MPPT control regulates the absorbed power from the panel. The regulated power value is about 40 W at an irradiance equal to 1000 W/m\({}^{2}\), 30 W at 800 W/m\({}^{2}\) and around 35 W at a solar irradiance of 900 W/m\({}^{2}\). The current-voltage and power-voltage characteristics of the PV module can be seen in Figure 26. During the simulation, the instantaneous position of the operating point (OP) on the current-voltage (I-V) characteristic is shown with the green arrow, while the black arrow points to the instantaneous position of the operating point on the power-voltage (P-V) characteristic. The system is able to reach the MPP, even if the OP is located before or after the MPP. The MPP can be found at the point marked on the graph with \"A\". Because the load was initially set to \(R\) = 450 \(\Omega\), the characteristics passed through the MPP, and overpassed point \"E\". Changing the value of the load to \(R\) = 325 \(\Omega\) determined the return to point \"A\", but overpassed point \"A\" to the left. Adjusting the resistor to \(R\) = 350 \(\Omega\) caused the return to point \"A\" but slightly exceeded to the right, with small oscillations around point \"A\". When \(T_{4}\) = 37 ms, the output resistance was changed to \(R\) = 360 \(\Omega\), which determined the return to and placement in point \"A,\" corresponding to the MPP. A step transition in solar irradiance from \(G_{1}\) = 1000 W/m\({}^{2}\) to \(G_{2}\) = 800 W/m\({}^{2}\) produced a displacement from points \"A\" to \"B\" and an evolution on the PV characteristic related to point \"C\". A step increase in the irradiance to 1000 W/m\({}^{2}\) produced a jump of the characteristics from \"C\" to \"D\" and a progression of the PV characteristic that ended with  
Figure 25: Simulation of input and output power during time according to the proposed scenario. the value of the solar irradiance corresponding to point \"A\". Changing the value of the load to \(R=460\)\(\Omega\) determined the exceedance of point \"A\" to the right. Because at \(T_{8}=135\) ms, the irradiance was set from \(G_{3}=1000\) W/m\({}^{2}\) to \(G_{4}=900\) W/m\({}^{2}\), again a jump took place from point \"E\" to point \"F\" and a search of the MPP on the characteristic corresponding to 900 W/m\({}^{2}\).