With the increase of power utilization rate of renewable energy systems and the profound studies of DC microgrids, DC distribution systems are getting more attention. To improve the quality of DC bus, it is necessary to consider the voltage fluctuations caused by loop switching such as battery management and maximum power output in the system. An optimization method is proposed to accelerate the switching process of multiple control loops, especially for multi-module expansion, which can improve the performance of dynamic response The proposed method just requires the addition of a few devices to the circuit structure and realizes nonlinear control, with which the conditional intervention only happens during transient processes without affecting the steady-state loop design. Compared with traditional methods, this method can achieve power expansion of the system as well as a quick response under load step or bus voltage overshoot.