DC microgrids have high energy utilization

flexible dispatch

and high reliability

and they are becoming an important research direction in the field of distributed energy consumption. The bus equivalent impedance is a key parameter for the structural optimization and control strategy design of DC microgrids

and its accurate calculation and measurement are of great significance. However

current measurement methods still suffer from low accuracy and complex measuring setups

and there remains considerable room for improvement in the estimation and measurement of equivalent impedance. To address these issues

this paper introduced an impedance measurement method based on energy and signal composite modulation. The impedance measurement signal was generated by modulating the power converter's switching frequency

eliminating the need for additional complex devices. Using time-division multiplexing with selected frequencies enabled efficient parallel multi-frequency impedance measurement. An optimal measurement frequency model was established by analyzing system resonance and filtering constraints. Using the selected frequency for power switch modulation

time-division multiplexing technology was applied to achieve efficient parallel impedance measurement at multiple frequencies

thereby enhancing both the effectiveness of signal injection and the measurement accuracy. Experimental results demonstrated that the proposed method significantly enhanced the measurement accuracy of the equivalent impedance

with errors of less than 5%

and provided technical support for impedance evaluation and optimal design of DC microgrids.