Talkative Dual Active Bridge Converter Employing Spread Spectrum Modulation to Mitigate EMI

The expansion of AC distribution systems and the development of DC microgrids have required communication via power lines to monitor the status of the demand sides and the condition of transmission lines. In distribution systems, the conventional method using power lines requires separate signal conversion devices and is not highly effective due to the influence of the power lines. Therefore, talkative power conversions, which use the output voltage ripple of the power converter and the variations in the PWM carrier to transmit the communication signal, have been investigated. However, EMI filters are usually needed considering the EMI issues in high-speed switching converters. These issues can lead to challenges in communication accuracy. Therefore, reducing EMI is essential to obtain high power density and ensure accurate communication. This study employs a spread spectrum modulation (SSM) to mitigate the EMI of the dual active bridge (DAB) converter and embed communication data into the output voltage ripples. The design parameters of the SSM are investigated for the controller design to demodulate transmitted data. Experimental results verify the successful transmission of the communication data through a 1 kW DAB converter prototype.