The communication system of a microgrid can transfer the information of electricity price, power consumption and so on between users and the control centre, which is of great significance to improve the efficiency and sus-tainability of power facilities. In this paper, a bidirectional DC-AC converter topology is proposed to achieve the composite transmission of power and signals in microgrids. Because the transmitted signals are modulated by power switches of converters and integrated into the currents, the cost of signal couplers can be saved and the circuit structure can be simplified. In order to verify the feasibility of the proposed method, a simulation model of the proposed converter is implemented in Matlab/Simulink. With the power supply frequency of 50 Hz, when the converter operates in the inverter mode and rectifier mode, the data transmission rate can reach 120 bit/s and 48 bit/s, respectively.