Parallel capacity-expansion control and implementation method for battery packs

The invention discloses a parallel capacity-expansion control and implementation method for a plurality of battery packs. An independent battery pack unit is formed through a control module serially connected onto a battery pack with certain voltage, the control module consists of equivalent variable battery modules, and the control module is a control device with the functions of detecting the voltage difference between busbar voltage Vbus+, Vbus- and the terminal voltage of the battery pack and controlling the charging current of the battery pack. The independent battery pack unit uses two terminals of Vbus+ and Vbus- as input and output of busbar, and the connection manner of the battery pack unit is as follows: the input and output terminal Vbus+ of a positive busbar is connected to the positive pole of the battery pack, the negative pole of the battery pack is connected to the Vs terminal of the control module, and the Vbus- terminal of the control module is connected with the input and output terminal V