A Modular Multilevel Converter, comprising: multiple sub-modules (110, 120) connected in series with each other; and a controller for controlling on/off switching of the sub-modules (110, 120), wherein: the multiple sub-modules (110, 120) include N sub-modules, which participate in operation of the MMC, and M redundant sub-modules, which participate in the operation in place of a failing sub-module when at least one of the N sub-modules fails; the controller switches on a sub-module if a carrier signal assigned thereto is higher than a preset reference signal, and switches off a sub-module if a carrier signal assigned thereto is lower than the preset reference signal, among the N+M sub-modules (110, 120) to which the carrier signals are assigned; each of the carrier signals (41, 42, 43) of the N+M sub-modules (110, 120) is configured such that a range from a top to a rest position thereof is not balanced with a range from a bottom to the rest position thereof, such that when the reference signal oscillates within a top-to-bottom range from -A to +A, each of the carrier signals (41, 42, 43) oscillates within a top-to-bottom range from -A to + (A × (N + M) / N); and N+M carrier signals are assigned to the N+M sub-modules (110, 120), respectively, and N sub-modules, selected from among the N+M sub-modules (110, 120), rotationally participate in the operation of the MMC. multiple sub-modules (110, 120) connected in series with each other; and a controller for controlling on/off switching of the sub-modules (110, 120), wherein: the multiple sub-modules (110, 120) include N sub-modules, which participate in operation of the MMC, and M redundant sub-modules, which participate in the operation in place of a failing sub-module when at least one of the N sub-modules fails; the controller switches on a sub-module if a carrier signal assigned thereto is higher than a preset reference signal, and switches off a sub-module if a carrier signal assigned thereto is lower than the preset reference signal, among the N+M sub-modules (110, 120) to which the carrier signals are assigned; each of the carrier signals (41, 42, 43) of the N+M sub-modules (110, 120) is configured such that a range from a top to a rest position thereof is not balanced with a range from a bottom to the rest position thereof, such that when the reference signal oscillates within a top-to-bottom range from -A to +A, each of the carrier signals (41, 42, 43) oscillates within a top-to-bottom range from -A to + (A × (N + M) / N); and N+M carrier signals are assigned to the N+M sub-modules (110, 120), respectively, and N sub-modules, selected from among the N+M sub-modules (110, 120), rotationally participate in the operation of the MMC. the multiple sub-modules (110, 120) include N sub-modules, which participate in operation of the MMC, and M redundant sub-modules, which participate in the operation in place of a failing sub-module when at least one of the N sub-modules fails; the controller switches on a sub-module if a carrier signal assigned thereto is higher than a preset reference signal, and switches off a sub-module if a carrier signal assigned thereto is lower than the preset reference signal, among the N+M sub-modules (110, 120) to which the carrier signals are assigned; each of the carrier signals (41, 42, 43) of the N+M sub-modules (110, 120) is configured such that a range from a top to a rest position thereof is not balanced with a range from a bottom to the rest position thereof, such that when the reference signal oscillates within a top-to-bottom range from -A to +A, each of the carrier signals (41, 42, 43) oscillates within a top-to-bottom range from -A to + (A × (N + M) / N); and N+M carrier signals are assigned to the N+M sub-modules (110, 120), respectively, and N sub-modules, selected from among the N+M sub-modules (110, 120), rotationally participate in the operation of the MMC.