Power electronics solutions for BESS integration and management

As the space industry evolves towards more powerful spacecraft, the demand for high power output and efficient power management is more critical than ever. Spacecraft power systems must support higher bus voltages while maintaining high reliability, compact design, and minimal energy loss. Conventional power architectures, which process the full power load, are limited in efficiency and scalability, particularly under high power demands. An alternative approach that accommodates higher bus voltages without altering the solar arrays and load voltages in conventional power architectures is Partial Power Processing (PPP). This converter solution processes only a fraction of the total energy, enabling higher efficiency, reduced component stress, and flexible, scalable designs that suit space sector’s growing power demands. Nevertheless, the efficiency of a PPP converterbased system is a non-linear function of the converter’s own efficiency, which imposes constraints on the voltage gain achievable by the converter. PPP converters are generally more efficient than full-power processing systems only when narrow input-output voltage differences are applied. Additionally, PPP architectures lack inherent galvanic isolation, making them unsuitable for applications with strict isolation requirements. In these cases, alternative solutions or additional interconnection stages may be necessary, potentially reducing the overall advantages of PPP. This thesis explores four primary objectives to address these challenges. First, it identifies the contexts in which PPP architectures are advantageous, particularly in applications that demand high efficiency and power density within limited space. A detailed analysis and comparison of series and parallel PPP configurations, along with the development of a reconfigurable PPP architecture to optimize efficiency by dynamically managing voltage gaps, are addressed and deeply analyzed. Second, it focuses on the design of PPP converters, addressing component stress, architecture selection, and complex trade-offs to balance efficiency and cost. To validate these findings, a prototype flyback PPP converter was developed, achieving a peak efficiency of 99.12%, demonstrating the potential of PPP to significantly reduce energy losses and component stress in high-power BESS systems. Third, the thesis explores a capacitive coupling solution to improve cross-regulation in multi-output flyback converters, which is critical for systems requiring auxiliary power supplies or for applications like cell balancing in BESS, where load balancing accuracy is essential. Conventional methods, such as multi-loop feedback or post-regulation stages, usually add both complexity and cost. This low-cost, low-complexity capacitive coupling approach eliminates the need for complex feedback systems, effectively minimizing cross-regulation errors in applications with unbalanced loads, without compromising converter efficiency. Fourth, the thesis investigates solutions for integrating mandatory isolation within PPP converters, utilizing capacitive coupling to meet safety and operational standards without the size, cost, and efficiency limitations of traditional magnetic transformers. By leveraging Gallium Nitride (GaN) technology for high-frequency switching, this approach achieves a compact and efficient design that minimizes power losses typically associated with magnetic cores. Experimental validation confirms the isolation method’s effectiveness, demonstrating high efficiency with negligible losses. These findings advance the application of PPP in high-power systems, establishing methodologies for integrating BESS in spacecraft power systems and contributing to high-efficiency power electronics for the space industry.