Electromagnetic characteristic analysis of a new dual-rotor hybrid excitation starter generator in generating mode

To address the low power density and limited magnetic field regulation capability of conventional single-excitation starter generators when operating in generating mode, a dual-rotor hybrid excitation starter-generator (DR-HESG) is proposed. The permanent magnet (PM) rotor adopts an asymmetric-pole structure to reduce cogging torque and enhance power density, while the electric excitation (EE) rotor employs a novel brushless claw-pole topology to improve structural reliability and field regulation capability. First, a Carter coefficient expression that accounts for both rotor and stator slotting effects is derived, from which the key structural parameters of the rotor and stator slots governing the main air-gap flux density are identified. Subsequently, a multi-objective optimization is performed with the fundamental amplitude and total harmonic distortion (THD) of the air-gap flux density as objectives, achieving optimal parameter matching. Finally, finite element analysis (FEA) of the electromagnetic characteristics of the optimized DR-HESG is conducted, and a prototype test bench is constructed for experimental validation. The results demonstrate that the proposed DR-HESG exhibits excellent voltage stabilization and regulation performance in generating mode.