## 5 Boost Converter CCM/DCM Mode Analysis with Variations in L and Weather Conditions  
The design and operation of the inductor 'L' and its effect on different portions of the I-V curve through D plays an integral part in the conduction modes of a boost converter. Moreover, the operation of a dc-dc converter in CCM or DCM is impacted by irradiance and temperature variations due to the change in the I-V characteristics of the PV array [33].  
To analyze the impact on the operational mode of the boost converter, a PV system can be analyzed for different inductor 'L' values versus variations in weather conditions and different operating points of the I-V curve. In this study, the first inductor value is estimated through Equation (4) and installed in the boost converter. Then, irradiance and temperature conditions are configured at certain values. Under these specific weather conditions, the PV array settings for different operating points on the I-V curve are established, i.e., from the short-circuit current '\(I_{sc}\)' point to the open-circuit voltage '\(V_{oc}\)' point, using variations in D (0 to 1). At each operating point, the operation of the boost converter in CCM mode or DCM mode is identified. Finally, the operating points when the PV array is under the influence of DCM mode are marked on the I-V curve of the PV array. Note that this loop is repeated for different values of the inductor 'L', where for every inductor value the irradiance is varied from 1000 \(\frac{W}{m^{2}}\) to 100 \(\frac{W}{m^{2}}\) at 0 \({}^{\circ}\)C, 25 \({}^{\circ}\)C, and 50 \({}^{\circ}\)C temperature values and operation in CCM or DCM is evaluated against each operating point on the I-V curve. The details of the PV array and simulation setup are explained in the upcoming section.  
In this context, Figure 4 represents the system behavior at 1000 \(\frac{W}{m^{2}}\) to 100 \(\frac{W}{m^{2}}\) when temperature is fixed at 25 \({}^{\circ}\)C, where the inductor is designed through Equation (4) at a ripple current of 40% of \(I_{mpp}\) in Figure 4a, 20% of \(I_{mpp}\) in Figure 4b, and 10% of \(I_{mpp}\) in Figure 4c. The marks on the I-V curves in each of these figures indicate the converter's operation in DCM mode. The same simulation experiment was repeated excluding the temperature variaton, which was set at 0 \({}^{\circ}\)C; the resulting I-V curves are displayed in Figure 5. Likewise, Figure 6 shows the I-V curves when the temperature was set at 50 \({}^{\circ}\)C.  
Figure 4: I–V curves at different irradiance conditions at 25 \({}^{\circ}\)C with inductor designed at (a) 40% of \(I_{mpp}\)  
Through these studies and subsequent graphical analysis, the following findings were established and used as the basis for developing the MPP algorithm:  
* At high irradiance values, if the converter is operating in the constant current region or MPP zone, the converter stays in CCM. However, if it moves towards the Voc region, the converter enters DCM.
* At low irradiance values, i.e., from 250 \(\frac{W}{\text{m}^{2}}\) and below, the converter may operate in DCM mode even in the MPP region due to the low source current from the PV array.
* In general, the P&O algorithm starts the first run from the \(V_{oc}\) region, i.e., in DCM mode. This means that if the algorithm is operating with a low voltage step it may become confused in this region, resulting in low convergence speed and poor dynamic efficiency.
* Because the P&O algorithm continues to searching the MPP under varying weather conditions, it may enter the DCM region frequently, potentially disrupting MPP tracking if it becomes caught in this region for several iterations.  
Note that on the graphs shown in Figures 4-6, the marked points are the operating points when the boost converter is in DCM.