Modular multilevel converters(MMC) face challenges of increased power losses during circulating current control

which restricts the improvement of their operational efficiency. To address this issue

a power loss model is constructed for the conduction and switching losses of MMC devices

and a loss-optimized circulating current control method is proposed. The relationship between the injected DC circulating current component and the amplitude of the double-frequency circulating current is discussed. Based on this

the optimal values of the amplitude and phase of the injected circulating current are solved to achieve global optimization of power loss. Meanwhile

the performance of the proposed method is analyzed to reveal the influence mechanism between power loss and capacitor voltage ripple. Simulation and experimental tests verify the feasibility and effectiveness of the proposed method.