| Micro-grid inverters have two working modes: when the utility is normal, a micro-grid inverter can work in grid-connected mode, and when the utility fails, it should operate in islanding mode to power local loads continuously. To achieve seamless transfer between the two modes, improved methods for control loop transition and phase locking are proposed in this paper. In addition, micro-grid inverters suffer from the grid voltage, which is replete with background harmonics in grid-connected mode. Hence, based on T/6 repetitive control, which has a six-fold re-sponse speed-up compared with conventional repetitive control, a harmonic current suppression control method is introduced. Finally, these control methods are integrated with a micro-grid inverter, and an experimental prototype is tested to verify the effectiveness of the proposed strategy.