Embodiments of the present disclosure provide a method for controlling a converter and a converter system. The method includes obtaining voltage signals indicating phase voltages of three phases at AC side of a converter, determining, based on the voltage signals, carrier signals of a three-phase switching branches of the converter, wherein carrier signals of two of three phases have the same phase with each other and have a different phase from a carrier signal of the rest phase of the three phases, and magnitude of a phase voltage of the rest phase is between the phase voltages of the two phases, and generating, based on the determined carrier signals and modulation wave signals of the three-phase switching branches, control signals of the three-phase switching branch.