Improved turboelectric propulsion system analysis method for electrified aircraft conceptual design

A fundamental Hybrid Electric Propulsion System (HEPS) configuration, the turboelectric propulsion system, uses generators and rectifiers for power generation. Since the efficiency of these components varies across mission segments with electrical characteristics and control strategies, analysis and sizing methods that reflect such variations are essential for reliable early-phase design. However, most prior studies have adopted fixed efficiency values or relied on limited efficiency maps for each component, which can reduce the reliability of early-phase sizing results and limit assessment of aircraft-level effects of efficiency variation, such as system weight and payload. This study developed analysis modules for power-generating components and integrated them into the conceptual sizing framework for HEPS AAM aircraft. The generator module employed an equivalent circuit model with a Maximum Power Per Ampere (MPPA) control strategy, the rectifier module used an average loss model, and the turboshaft engine was represented using Referred Parameter Turboshaft Engine Model (RPTEM) data. These models were implemented in RISPECT+ through an iterative sizing loop updating component efficiencies according to mission operating conditions. Applied to a representative turboelectric AAM case and compared with a conventional fixed-efficiency approach, the results showed that EPS weight increased by approximately 12.6%, TMS weight increased by 17.4%, and payload decreased by 36.3%. These results highlight the importance of incorporating variable-efficiency effects and component-level electrical analysis into the early design phase of HEPS AAM aircraft, as demonstrated for the turboelectric configuration considered in this study.