Active cell balancing

A method comprising:

• connecting a capacitor and an inductor between a first battery terminal and a second battery terminal of a first battery cell to provide a first voltage across the capacitor, in which a capacitor terminal of the capacitor is connected to the first battery terminal, and an inductor terminal of the inductor is connected to the second battery terminal;
• disconnecting the inductor terminal from the second battery terminal;
• connecting the inductor terminal to the first battery terminal to provide the first voltage across the inductor;
• disconnecting the capacitor terminal from the first battery terminal;
• and
• connecting the capacitor terminal to a third battery terminal of a second battery cell to transfer charge from the capacitor to the second battery cell at a rate based on the first voltage and an inductance of the inductor.

A system comprising:

• an integrated circuit including:
• a first transistor coupled between a first battery terminal and a capacitor terminal, the first transistor having a first transistor control terminal;
• a second transistor coupled between the capacitor terminal and a second battery terminal, the second transistor having a second transistor control terminal;
• a third transistor coupled between a third battery terminal and an inductor terminal, the third transistor having a third transistor control terminal;
• and
• a fourth transistor coupled between the inductor terminal and a fourth battery terminal, the fourth transistor having a fourth transistor control terminal;
• and
• a control circuit having a control input and first, second, third, and fourth control outputs, in which the first control output is coupled to the first transistor control terminal, the second control output is coupled to the second transistor control terminal, the third control output is coupled to the third transistor control terminal, and the fourth control output is coupled to the fourth transistor control terminal;
• and
• a capacitor and an inductor coupled between the capacitor terminal and the inductor terminal.

A system comprising:

• a first module including one or more pairs of first half bridge circuits coupled between a first terminal and a second terminal, each of the one or more pairs of first half bridge circuits having a respective first current terminal, and the first module including a first inductor and a first capacitor coupled between the first current terminals of each pair of the first half bridge circuits;
• a second module including one or more pairs of second half bridge circuits coupled between a third terminal and a fourth terminal, the third terminal coupled to the second terminal, each of the one or more pairs of second half bridge circuits having a respective current terminal, and the second module including a second inductor and a second capacitor coupled between the second current terminals of each pair of the second half bridge circuits;
• a third half bridge circuit coupled between the first terminal and the second terminal, the third half bridge circuit having a third current terminal and a first control terminal;
• a fourth half bridge circuit coupled between the third terminal and the fourth terminal, the fourth half bridge circuit having a fourth current terminal and a second control terminal;
• an inductor and capacitor (LC) network coupled between the third and fourth current terminals;
• a control circuit having a control input and first and second control outputs, in which the first control output is coupled to the first control terminal, and the second control output is coupled to the second control terminal.