Abstract: In DC microgrids, three-phase unbalanced loads connected to the bus through inverters generate power fluctuations at double frequency, resulting in second-order ripple on the DC bus, affecting the power quality and reliability of the microgrid. To address this issue, this paper proposes a method for suppressing DC bus voltage ripple through coordinated control of multiple inverters. This method solves the problem of traditional ripple suppression methods affecting the system's original operating state and enhances the effect of the suppression. The mechanism and superposition characteristics of the second-order ripple are analyzed. A solution is proposed to reduce the total ripple current amplitude by controlling the phase difference. To implement this solution and reduce the fluctuation of load voltage during transient, a reference phase optimization model is established to calculate the optimal reference phase. An inverter phase control strategy is proposed to enable the ripple current phase to track the reference phase, and a segmented phase regulation is adopted to prevent voltage fluctuations. The proposed method does not require additional devices, has minimal impact on the system's original operating state, and can handle scenarios with multiple unbalanced loads. Under certain conditions, the second-order ripple in the bus can be reduced by 95%. Simulation results demonstrate the effectiveness of the proposed control strategy.