This paper presents a new solution for microgrid inverters in terms of circuit topology and control structure. The combined three-phase four-wire inverter, which is composed of three single-phase full-bridge inverter circuits, is adopted. The control structure is divided into three main parts: the is landing detection unit, the grid-connected controller, and the is landing controller. The inverters automatically operate in the grid-connected or the is landing mode using the is landing detection unit. In the grid-connected mode, the controller is composed of the sliding-mode current inner loop and the constant power control outer loop. The inverter effectively rejects the grid voltage disturbances and the parameter uncertainties. Moreover, the inverter also provides constant currents to the grid. In the is landing mode, the controller is based on the sliding-mode voltage inner loop, the virtual resistive output-impedance loop, and the improved P/Q sharing control loop. The controller guarantees the parallel operation of the micro-grid inverters with robustness performance and a good power sharing accuracy. The dynamic characteristics and the high disturbance rejection performance during the transition is ensured. The theoretical analysis and test results validate the proposed control strategy effectiveness.