*3.3. Matching Stage: SEPIC Converter*

The SEPIC is a direct-voltage-to-direct-voltage converter that will allow the output to be greater than, less than, or equal to the input voltage [28]. This is because the voltage of the converter is controlled by the duty cycle. In addition, the SEPIC is analogous to a buck-boost converter with the benefit of having a noninverting output. In effect, it ensures low current ripples. In terms of construction, the SEPIC converter consists of a power switch (IGBT; MOSFET, Thyristor, etc.), a diode, inductors (*L*1, *L*2), and capacitors (*C*1, *C*2). Figure 4 shows the electrical diagram of this converter. The input inductance *L*<sup>1</sup> of the circuit makes the whole SEPIC converter look like a boost converter. This converter also has the advantage of isolating the input and output by means of the coupling capacitor *C*1, which protects against a short circuit or an overload at the output. Moreover, the SEPIC has the advantage of being able to cut its output voltage down to zero voltage, unlike a boost converter where the lowest output voltage is equal to the input voltage.

**Figure 4.** Electrical diagram of a SEPIC converter [28].

The relation between the load voltage and the converter input voltage is given by [28,29]:

$$V\_{OUT} = \frac{1-\mathfrak{a}}{\mathfrak{a}} V\_{IN} \tag{5}$$

where *VOUT* is the output voltage, *VIN* is the input voltage, and α is the duty cycle.

Table 3 summarizes the sizing results for the SEPIC converter applied to the studied solar pumping system.

**Table 3.** SEPIC converter features.

