*5.2. Experimental Results and Discussion*

The output voltage is shown in Figure 16 (Ch2). The load voltage is recorded at −18 V with a low voltage ripple. The driving voltage of IRF540N is shown in Figure 16 (Ch1). The applied voltage reaches a peak of 12 V, with a duty cycle is about 70% (35 μs). Accordingly, the inductor *L*<sup>1</sup> voltage is plotted in Figure 17.

**Figure 16.** Ch1: Input Voltage, Ch2: Output Voltages.

**Figure 17.** Ch1: *VL*1, Ch2: *VL*2.

As observed in Figure 17 (Ch1), the inductor voltage reaches 12 V (the input voltage) during the switch *M*1's turn-on time. However, when the switch is turned off (with an off time of approximately 15 μs), the inductor voltage decreases to −6 V. Similarly, during the

switch *M*1's turn-on time, the inductor *L*<sup>2</sup> exhibits a voltage of a 3 V across its terminals. Conversely, when the switch *M*<sup>1</sup> is turned off, the inductor *L*<sup>2</sup> displays −10 V, see Figure 17 (Ch2). In addition, the coupling capacitor has 7 V across its terminal, which corresponds to the difference between the input and output voltage. Consequently, the rated voltage of the selected voltage of *C*<sup>1</sup> should be around 15 V. This confirms that the selected coupling capacitor has a lower rated voltage than the same one in the Cuk converter (in the Cuk converter case, the rating voltage of the coupling capacitor must be selected around 45 V. This reduces the selected rated voltage of *C*<sup>1</sup> in the proposed converter by 66.67% compared to the same capacitor of Cuk converter, as seen in Figure 18.

**Figure 18.** *C*<sup>1</sup> Voltage.

The drain-source voltage of the IRF540N is depicted in Figure 19, while the diode voltage is plotted in Figure 20. The MOSFET is operated with a duty cycle of 70%. It can be seen from these Figures that during the switch turn-off period, there is some ringing present in the voltage waveform. This ringing is related to some reasons, such as: one reason is the resonance between *L*<sup>1</sup> and the MOSFET's parasitic capacitance during the energy transfer period. It is not possible to resonate *L*<sup>2</sup> and *C*<sup>1</sup> with *L*1, because the resonant frequency of this combination is about 28 kHz. Similarly, there is no possible resonant between *L*<sup>2</sup> and *C*<sup>1</sup> with *L*1, as their resonance frequency is about 40 kHz, significantly lower than the frequency depicted in Figures 19 and 20.

**Figure 19.** Drain-source voltage.

**Figure 20.** Diode voltage.

The second reason is the possible resonance between the inductance of *L*<sup>1</sup> and the capacitance of parasitic capacitance of the used passive prob. The third possible reason may be related to the poor copper board used which causes some EMI issues. However, these reasons can be easily overcome with very good PCB design and using advanced measuring devices. In sum, Table 5 provides a comprehensive comparison between the Cuk converter and the Mahafzah converter, considering their main features under the same operating conditions.


**Table 5.** A comprehensive compression between Cuk and Mahafzah converters.

" √" indicates which converter is better for each parameter.

Overall, based on the information provided in the table, the Mahafzah converter demonstrates certain advantages over the Cuk converter in terms of the reduced coupling capacitor voltage, improved efficiency, and shorter transient period. However, it is important to note that the table does not provide specific quantitative values or detailed explanations for each feature, making it difficult to conduct a thorough analysis without further information.
