Bi-directional battery charging circuit with voltage regulation control

An electric system, having an input terminal to receive an input voltage, a system output terminal to provide a system voltage, and N charging output terminals coupled to N loads respectively, wherein N is an integer greater than 1, the electric system comprising:

• an input switch coupled between the input terminal and a first terminal;
• a switching circuit, coupled between the first terminal and the system output terminal, wherein the switching circuit is configured to work in a buck mode to convert a boost output voltage at the first terminal to the system voltage, or to work in a boost mode to convert the system voltage to the boost output voltage;
• N charging units, wherein for each integer i from 1 to N, the ith charging unit of the N charging units has an input terminal coupled to the first terminal, and an output terminal coupled to the ith charging output terminal of the N charging output terminals for charging the ith load of the N loads;
• and
• a voltage control module, having N input terminals coupled to the N charging units respectively, wherein the voltage control module is configured to sense N charging currents passing through the N charging units respectively, and to adjust the boost output voltage based on the N charging currents, wherein when the N charging currents are higher than or equal to a fast charge threshold current, the boost output voltage is controlled to decrease from an initial voltage.