Abstract: The application relates to a system for charging a battery of an electrical vehicle. The electrical vehicle charging system of the present application is helpful for decreasing the converter capacity while maintaining the charging capacity and electrical vehicles with various nominal voltages can be charged simultaneously. In one aspect the system for charging an electrical vehicle includes: a plurality of central converters, at least one switch electrically connected to the central converters, at least one transformer electrically connected to an external AC power supply, at least one distributed converter for supplying at least one distributed DC voltage with a level below that of the central converter, and a controller connected to the at least one switch.

Abstract: The application relates to a system for charging a battery of an electrical vehicle. The electrical vehicle charging system of the present application is helpful for decreasing the converter capacity while maintaining the charging capacity and electrical vehicles with various nominal voltages can be charged simultaneously. In one aspect the system for charging an electrical vehicle includes: a plurality of central converters, at least one switch electrically connected to the central converters, at least one transformer electrically connected to an external AC power supply, at least one distributed converter for supplying at least one distributed DC voltage with a level below that of the central converter, and a controller connected to the at least one switch.

Abstract: The present invention relates to Voltage balancing control method for modular multilevel converter is characterized that, it includes some steps as follows: 1) Determine the leg current direction is positive or negative; 2) Find out the highest sub module on output state whose capacitor voltage amplitude is the maximum, and find out that on bypass state whose capacitor voltage amplitude is the minimum; 3) Determine whether the sub module inputs or bypass operation; this method avoided switching arbitrariness of the sub module, and decreased the switching frequency of the sub module. The capacitor voltage balancing control of the sub module proposed by the method is more suitable to be applied in the field of high voltage and large capacity converter that has large numbers of sub modules.