Balancing method of a switchable battery device by short-circuiting of its output

1 . A battery pack device comprising:

a first terminal;

a second terminal;

a plurality of energy storage elements configured to be set in series or in parallel between said first terminal and said second terminal,

wherein each of the energy storage elements includes:

at least one switch for connecting the energy storage element in series and/or in parallel with at least one other energy storage element, or to disconnect the energy storage element from one or more other energy storage elements; and

at least one conductor for conducting a main current parallel to the energy storage element, when the energy storage element is disconnected or is not connected in series and/or in parallel with one or more other energy storage elements;

at least one switch configured to establish a short-circuit between said first terminal and said second terminal of the battery pack device when the battery pack device is disconnected or provides zero voltage;

a control circuit configured to:

select at least one first energy storage element in a first state and at least one second energy storage element in a second state, the first state and the second state each being a function based on at least one of charge, voltage, state-of-health, temperature, impedance, and available power of a respective one of the first energy storage element and the second energy storage element;

circulate a current from the first energy storage element to the second energy storage element when said first terminal and said second terminal of the battery pack device are short-circuited; and

stop circulating the current when a value of the first state of the first energy storage element is substantially equal to a value of the second state of the second energy storage element.

2 . The battery pack device according to claim 1 , wherein each of the energy storage elements includes at least one of one or more electrochemical cells, one or more capacitance elements, one or more supercapacitance elements, and/or one or more storage cells.

3 . The battery pack device according to claim 1 , wherein the control circuit is further configured to:

calculate, for each of the energy storage elements, a priority coefficient (C cell_i ), which defines a charging or discharging order of the energy storage elements, the priority coefficient (C cell_i ) being normalizable; or

correct the priority coefficient (C cell_i ) of at least one of the energy storage elements in order to vary a priority of the at least one of the energy storage elements.

4 . The battery pack device according to claim 3 , wherein the control circuit is further configured to:

select the at least one first energy storage element and the at least one second energy storage element such that the priority coefficient of the first energy storage element is higher than the priority coefficient of the second energy storage element; and

circulate a current from said first energy storage element to at least said second energy storage element when the first terminal and the second terminal of the battery pack device are short-circuited.

5 . The battery pack device according to claim 4 , wherein the control circuit is further configured to perform at least one of:

regulating the current that circulates from the first energy storage element to at least the second energy storage element when the input and the first terminal and the second terminal are short-circuited; and

causing a constant current to circulate from the first energy storage element to the second energy storage element and then causing a constant-voltage current to circulate from the first energy storage element to the second energy storage element.

6 . The battery pack device according to claim 5 , wherein the control circuit is further configured to:

regulate the current that circulates from the first energy storage element to at least the second energy storage element when the first terminal and the second terminal are short-circuited according to a discrepancy between the priority coefficient or the first state of the first element and the priority coefficient or the second state of the second element or according to a discrepancy between at least the priority coefficient or the first state of the first element or the priority coefficient or the first state of the second element and an average of a priority coefficient or state calculated for several of the energy storage elements.

7 . The battery pack device according to claim 3 , wherein the control circuit is further configured to:

compare the priority coefficient (C cell_i ) of one or more of the energy storage elements and/or a sum of the priority coefficients (C cell_i ) of several energy storage elements, with an average (C moyen ) of the priority coefficients (C cell_i ) of at least one portion of the energy storage elements.

8 . The battery pack device according to claim 7 , wherein the control circuit is further configured to:

select n (n≥1) first energy storage elements in a first state-of-charge from among the energy storage elements whose priority coefficient (C cell_i ) is greater than the average (C moyen ) of the priority coefficient (C cell_i ) calculated for all of the energy storage elements;

select n (n≥1) second energy storage elements in a second state-of-charge from among the energy storage elements whose priority coefficient (C cell_i ) is less than the average (C moyen ) of the priority coefficients (C cell_i ) calculated for all of the energy storage elements;

circulate a current from said n first energy storage elements to said n second energy storage elements when the first terminal and the second terminal of the battery pack device are short-circuited; and

stop circulating the current when the priority coefficient of the n (n≥1) first energy storage elements is approximately equal to the priority coefficient of the n (n≥1) second energy storage elements.

9 . The battery pack device according to claim 8 , wherein the control circuit is further configured to:

calculate a first sum of voltages of at least one portion of the first energy storage elements whose priority coefficient (C cell_i ) is greater than the average (C moyen ) of the priority coefficients of all of the energy storage elements;

calculate a second sum of voltages of at least one portion of the second energy storage elements whose priority coefficient (C cell_i ) is less than the average (C moyen ) of the priority coefficients of all of the energy storage elements; and

circulate current between said at least one portion of the first energy storage elements and said at least one portion of the second energy storage elements.

10 . The battery pack device according to claim 1 , wherein the state of each of the energy storage elements is computed from charge and/or voltage of each respective one of the energy storage elements, including formulations in which the charge and/or the voltage is corrected based on temperature and/or state-of-health.

11 . The battery pack device according to claim 1 , further comprising at least one switch configured to reverse a polarity of one or more of the energy storage elements.