A universal starter-generator system, designed with the use of modern element base, for a flying apparatus corresponding to the concept of “more electrical aircraft” is considered. In order to ensure the operation of the autonomous starter-generator used for starting the flying apparatus auxiliary power installation, a small-sized step-up DC–DC converter is proposed, the converter being based on the switching capacitor structures (SCS) and having the 16 kW output power with a stabilized double polarity ± 135 V. The primary power source consists of two accumulating batteries of voltage 16–25 V. The converter double-cascade design of symmetrical channels ensures better energy and mass-sized parameters. The first non-regulated cascade is based on a three-time-step circuit using a resonance SCS. The output voltage stabilization is reached by the pulse-width regulation of the transistor switches in the second cascade realized on the two-time-step circuit based on a quasi-resonance SCS. Owing to high specific energy parameters of modern ceramic capacitors, the DC–DC converter size is reduced by the factor of 8, compared to the known design based on the classical technical solution for boost multi-cycle converters and Cook converters, and twice as compared with the known circuit a double active bridge using large and non-technological magnetic elements—reactors and transformers.