Innovative power system architectures for nanosatellites using high-efficiency converters and robust battery charge regulation strategy

This paper presents an innovative Electrical Power System (EPS) for nanosatellites that integrates a multi-junction solar PhotoVoltaic (PV) array with a Thermoelectric Generator (TEG) to harvest thermal gradients and sustain power generation under low irradiance. A Li-ion battery–supercapacitor pair complements the primary source, enhancing load regulation, reducing battery stress, and ensuring reliable, continuous power delivery. To maximize efficiency within the tight constraints of nanosatellite platforms, Gallium Nitride (GaN) transistors are employed for high-performance, low-loss power conversion, offering superior thermal management compared to Silicon Metal–Oxide–Semiconductor Field-Effect Transistors (Si-MOSFETs). Furthermore, a Double Integral Sliding Mode Control (DISMC) strategy is implemented to achieve optimal battery charge regulation, thereby reinforcing system stability and extending the overall lifespan of the proposed EPS architecture. Simulations under varying space conditions demonstrate that the proposed DISMC controller outperforms both PID and conventional SMC, reducing overshoot by more than 80 % in the Buck converter and 95 % in the Boost converter, with improvements in ripple and settling time of approximately 85 % and 83 %, respectively (as in the Buck converter case). Hardware validation further confirms excellent large-signal properties, showing consistent step-up and step-down responses. At the same time, the steady-state errors and input ripples observed with PID control (∼400 mV in Buck and ∼100 mV in Boost) were mitigated by SMC and nearly eliminated with DISMC. In addition to superior dynamic performance, efficiency testing revealed that the GaN-based synchronous buck converter achieved a peak efficiency of ∼95.7 %, compared to ∼89 % for the Si-MOSFET-based asynchronous design and slightly higher for the Si-MOSFET-based synchronous design, thereby establishing the proposed EPS as a highly efficient, reliable, and robust solution for nanosatellite applications.