Active energy balancing for energy storage systems

A method, comprising:

• coupling a first circuit with a first battery cell and a second battery cell, the first circuit comprising a first charge unit for storing energy transferred between the first battery cell and the second battery cell, the first charge unit comprising a resistor in parallel arrangement with an inductor, the resistor coupled with a first node of the first charge unit and a second node of the first charge unit and the inductor coupled with the first node of the first charge unit and the second node of the first charge unit;
• coupling, by the first circuit, the first node of the first charge unit with the first battery cell and with the second battery cell;
• coupling, by the first circuit the second node of the first charge unit with a first transistor of the first circuit and with a second transistor of the first circuit;
• controlling, by the first circuit, a first transfer of the energy from a first one of the first battery cell and the second battery cell to the first charge unit to store the energy via the inductor and the resistor;
• and
• controlling, by the first circuit, a second transfer of the energy from the first charge unit via the inductor and the resistor to a remaining one of the first battery cell and the second battery cell;
• coupling a second circuit with the second battery cell and a third battery cell, the second circuit comprising a second charge unit to store energy transferred between the second battery cell and the third battery cell, the second charge unit comprising a first node of the second charge unit coupled with the second battery cell and the third battery cell and a second node of the second charge unit coupled with a first transistor of the second circuit and a second transistor of the second circuit to control energy transfer between the second battery cell and the third battery cell via the second charge unit:
• coupling a third circuit with the second battery cell and a fourth battery cell that is not directly coupled with the first circuit or the second circuit:
• coupling, a first node of a third charge unit of the third circuit with the second battery cell;
• coupling a second node of the third charge unit with a first transistor of the third circuit and a second transistor of the third circuit that is coupled with the fourth battery cell:
• controlling, by at least one of the first transistor of the third circuit or the second transistor of the third circuit, a third transfer of the energy from the remaining one of the first battery cell or the second battery cell to the third charge unit of the third circuit to store the energy in the third charge unit;
• controlling, by the at least one of the first transistor of the third circuit or the second transistor of the third circuit, a fourth transfer of the energy from the third charge unit to the fourth battery cell;
• and
• causing, by a controller, the first transfer and the second transfer to be completed within a first cycle and the third transfer and the fourth transfer to be completed within a second cycle.

An energy storage system, comprising:

• a first circuit for energy transfer between a first battery cell and a second battery cell of the energy storage system, the first circuit comprising:
• a first charge unit of the first circuit to store energy transferred between the first battery cell and the second battery cell, the first charge unit comprising:
• a resistor coupled with a first node of the first charge unit and a second node of the first charge unit;
• and
• an inductor coupled with the first node of the first charge unit and the second node of the first charge unit and arranged in parallel with the resistor;
• the first node of the first charge unit coupled with a positive terminal of the first battery cell and with a negative terminal of the second battery cell;
• a first transistor of the first charge unit coupled with the second node of the first charge unit;
• and
• a second transistor of the first circuit coupled with the second node of the first charge unit, wherein at least one of the first transistor of the first charge unit and the second transistor of the first circuit are to control transfer of the energy between the first battery cell and the second battery cell, via the inductor and the resistor;
• a second charge unit to store energy transferred between the second battery cell and a third battery cell, the second charge unit comprising a first node of the second charge unit coupled with the second battery cell and the third battery cell and a second node of the second charge unit coupled with a first transistor of the second circuit and a second transistor of the second circuit to control energy transfer between the second battery cell and the third battery cell via the second charge unit;
• and
• a third circuit coupled with the second battery cell and a fourth battery cell that is not directly coupled with the first circuit or the second circuit;
• a third charge unit of the third circuit;
• a first node of the third charge unit coupled with the second battery cell and a second node of the third charge unit coupled with a first transistor of the third circuit and a second transistor of the third circuit that is coupled with the fourth battery cell, at least one of the first transistor of the third circuit or the second transistor of the third circuit to:
• control a third transfer of the energy from the remaining one of the first battery cell or the second battery cell to the third charge unit of the third circuit to store the energy in the third charge unit;
• and
• control a fourth transfer of the energy from the third charge unit to the fourth battery cell;
• and
• a controller configured to cause the first transfer and the second transfer to be completed within a first cycle and the third transfer and the fourth transfer to be completed within a second cycle.