Abstract: Compared to traditional permanent magnet motor, hybrid excitation synchronous generator (HESG) introduces excitation winding. The air gap magnetic field can be adjusted flexible by controlling the excitation current, which exhibits broad application prospects in systems such as aviation DC power generation that require wide speed range operation. Traditional strategy of independent controlling excitation or armature currents cannot fully utilize the control degrees of freedom for the HESG, limiting its speed range. To address this issue, a coordinated control strategy for excitation and armature currents that minimizes copper losses is proposed in this paper. Based on the field adjustment and speed expansion requirements of low-speed and high-speed operations, the Lagrange equations under different constraint conditions are given separately, achieving online allocation of excitation and armature currents. Experimental results show that compared to independent control of excitation and armature current, the coordinated control strategy can achieve higher efficiency and a wider speed region operation, simultaneously possessing good variable speed and stable voltage capabilities.