The present application relates to a rectification control system, a charger and a control method for a charger. The rectification control system includes: a Vienna rectifier, which includes input terminals and output terminals, an output capacitor circuit, and a rectifying circuit which includes a u-phase bridge arm branch, a v-phase bridge arm branch and a w-phase bridge arm branch, each bridge arm branch comprising a switch device and a bidirectional switch unit which are connected in series; a voltage acquisition unit, which is connected to the three input terminals and is configured to acquire voltages Uuv, Uvw and Uwu; a fault detection unit, which is connected to the bidirectional switch units and is configured to detect whether any of the bidirectional switch units fails; and a control unit, which is connected to the voltage acquisition unit and the fault detection unit and is configured to control closing or opening of three switch devices according to voltage input format, voltage connection mode and detection result of the fault detection unit, so as to switch circuit and working mode, making a charger suitable for applications in multiple scenarios and multiple formats.