This paper first introduces the high-frequency link (HFL) concept into the modular multilevel converter (MMC) topology, which can totally reduce the individual DC-link capacitors at the high-voltage (HV) side, and this type converter can be named as Isolated Modular Multilevel Converter (I-M2C) having basic triple ports of high-voltage AC (HVAC), high-voltage DC (HVDC), and low-voltage DC (LVDC), which is especially suitable for hybrid DC and AC application in power generation and transmission, such as Solid-State Transformer (SST), etc. Because of the positive voltage of submodules’ (SMs’) port based on hybrid AC and DC voltage conversion in I-M2C, there is no need for the bidirectional switches. The fundamental principle and applied Phase-Shifted Pulse Width Modulation (PWM) control scheme are given in detail. Experimental results are given to illustrate the efficient operating characteristics.