*2.1. ISOS Circuit Diagram*

An ISOS DC-DC converter is employed in high input voltage and high output voltage applications [43]. The ISOS converter configuration is shown in Figure 1, where modules are connected in series at the input and the output sides. The ISOS DC-DC converter shown in Figure 1 is needed for a high step-up ratio. This configuration is employed in high-voltage applications where neither the input side voltage nor the output side voltage is within the semiconductor devices voltage ratings. Such configuration enables low-voltage rating switches utilization.

By ensuring equal Input Voltage Sharing (IVS) and Output Voltage Sharing (OVS), the input voltage per module is Vin <sup>3</sup> , and the output voltage per module is Vo <sup>3</sup> . In which, Vin and Vo are the ISOS input voltage and ISOS output voltage, respectively. The features of the ISOS converter can be summarized in reduced voltage stress as well as the reduced power level per module, which facilitates the design of the converter. In the following Section, the SSM of the ISOS converter is studied using the FB-PS DC-DC converter.

**Figure 1.** Input-Series Output-Series (ISOS) DC-DC converter circuit diagram.
