Abstract: Multi-Port converters with both DC and AC ports are key devices for future hybrid DC&AC power grid. They often consist of cascaded two-port MMCs or DAB based converters which bring complex structure and difficult control design. A modular multilevel converter with three ports (TP-MMC), 2 AC ports and 1 DC port, was proposed by combining MMC arms with different types of submodules and full arm inductor scheme. Power could be transferred among the three ports freely. The nearest level modulation method for the proposed TP-MMC was designed. Mathematical model was established and the decoupling control strategy was proposed according to different balancing port selection. Circular current components were analyzed and the conclusion that the effective components in the circulating currents were DC and fundamental components was drawn. The circular current control strategy for circular current suppression was proposed. Simulation results show that the proposed TP-MMC and its modulation and control strategies can work effectively and provide precise AC outputs.