Power and current estimation for batteries
First Claim
1. A method for controlling an energy storage cell, the method comprising:
- (a) providing a predetermined upper voltage limit or lower voltage limit of the energy storage cell;
(b) providing a time horizon as a time difference from a present time to a future time;
wherein, with a repetition time period independent from the time horizon, repeating the following steps;
(c) measuring a present voltage level of the energy storage cell;
(d) calculating, by a control unit, a voltage difference between the present voltage level and the upper voltage limit or the lower voltage limit; and
(e) based on the voltage difference, the time horizon, and an equivalent circuit model comprising a capacitance and a resistance of the energy storage cell relating an electrical charge current or an electrical discharge current to a respective estimated voltage of the energy storage cell, determining, by the control unit, a maximum electrical charge current or a maximum electrical discharge current of the energy storage cell corresponding to the voltage difference, wherein the respective estimated voltage of the energy storage cell is less than or equal to the upper voltage limit during the time horizon in the case of an electrical charge current, or larger than or equal to the lower voltage limit during the time horizon in the case of an electrical discharge current; and
the method further comprising,(f) receiving at the control unit a request for a demanded electrical charge current or a demanded electrical discharge current for the energy storage cell;
(g) in response to the demanded electrical charge current being larger than the maximum electrical charge current, the control unit automatically limiting a current delivered to the energy storage cell to the maximum electrical charge current; and
(h) in response to the demanded electrical discharge current being larger than the maximum electrical discharge current, the control unit automatically limiting a current withdrawn from the energy storage cell to the maximum electrical discharge current;
wherein the maximum electrical charge current or maximum electrical discharge current (imax;
imin) is given by;
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Abstract
A method and a system are provided for determining a maximum charge current or a maximum discharge current of an energy storage cell of an energy storage device. The method includes providing a predetermined upper voltage limit or lower voltage limit, and providing a time horizon as a time difference from a present time to a future time. The method also include, with a repetition time period different from the time horizon, repeating measuring a present voltage level of the energy storage cell, calculating a voltage difference between the present voltage level and the upper voltage limit or the lower voltage limit, and determining the maximum charge current or maximum discharge current corresponding to the voltage difference and a model, such that the estimated voltage is within the voltage limits.
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Citations
13 Claims
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1. A method for controlling an energy storage cell, the method comprising:
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(a) providing a predetermined upper voltage limit or lower voltage limit of the energy storage cell; (b) providing a time horizon as a time difference from a present time to a future time; wherein, with a repetition time period independent from the time horizon, repeating the following steps; (c) measuring a present voltage level of the energy storage cell; (d) calculating, by a control unit, a voltage difference between the present voltage level and the upper voltage limit or the lower voltage limit; and (e) based on the voltage difference, the time horizon, and an equivalent circuit model comprising a capacitance and a resistance of the energy storage cell relating an electrical charge current or an electrical discharge current to a respective estimated voltage of the energy storage cell, determining, by the control unit, a maximum electrical charge current or a maximum electrical discharge current of the energy storage cell corresponding to the voltage difference, wherein the respective estimated voltage of the energy storage cell is less than or equal to the upper voltage limit during the time horizon in the case of an electrical charge current, or larger than or equal to the lower voltage limit during the time horizon in the case of an electrical discharge current; and the method further comprising, (f) receiving at the control unit a request for a demanded electrical charge current or a demanded electrical discharge current for the energy storage cell; (g) in response to the demanded electrical charge current being larger than the maximum electrical charge current, the control unit automatically limiting a current delivered to the energy storage cell to the maximum electrical charge current; and (h) in response to the demanded electrical discharge current being larger than the maximum electrical discharge current, the control unit automatically limiting a current withdrawn from the energy storage cell to the maximum electrical discharge current; wherein the maximum electrical charge current or maximum electrical discharge current (imax;
imin) is given by; - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for controlling an energy storage cell, the method comprising:
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(a) providing a predetermined upper voltage limit or lower voltage limit of the energy storage cell; (b) providing a time horizon as a time difference from a present time to a future time; wherein, with a repetition time period independent from the time horizon, repeating the following steps; (c) measuring a present voltage level of the energy storage cell; (d) calculating, by a control unit, a voltage difference between the present voltage level and the upper voltage limit or the lower voltage limit; and (e) based on the voltage difference, the time horizon, and an equivalent circuit model comprising a capacitance and a resistance of the energy storage cell relating an electrical charge current or an electrical discharge current to a respective estimated voltage of the energy storage cell, determining, by the control unit, a maximum electrical charge current or a maximum electrical discharge current of the energy storage cell corresponding to the voltage difference, wherein the respective estimated voltage of the energy storage cell is less than or equal to the upper voltage limit during the time horizon in the case of an electrical charge current, or larger than or equal to the lower voltage limit during the time horizon in the case of an electrical discharge current; and the method further comprising, (f) receiving at the control unit a request for a demanded electrical charge current or a demanded electrical discharge current for the energy storage cell; (g) in response to the demanded electrical charge current being larger than the maximum electrical charge current, the control unit automatically limiting a current delivered to the energy storage cell to the maximum electrical charge current; and (h) in response to the demanded electrical discharge current being larger than the maximum electrical discharge current, the control unit automatically limiting a current withdrawn from the energy storage cell to the maximum electrical discharge current; wherein the energy storage cell and a controller are modeled as a feedback control system, wherein the energy storage cell is modeled as a transfer function (G) from change in charge current or change in discharge current to a change in voltage given by; - View Dependent Claims (8, 9)
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10. A system for controlling an energy storage cell, the system comprising:
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a control unit; and a voltage measuring device; wherein the control unit is configured to, (a) receive a predetermined upper voltage limit or lower voltage limit of the energy storage cell; wherein, with a repetition time period independent from a predetermined time horizon being a time difference from a present time to a future time, the control unit is configured to repeat the following, (b) receive, from the voltage measuring device, a measurement of a present voltage level of the energy storage cell; (c) calculate a voltage difference between the present voltage level and the upper voltage limit or the lower voltage limit; (d) based on the voltage difference, the time horizon, and an equivalent circuit model comprising a capacitance and a resistance of the energy storage cell relating an electrical charge current or an electrical discharge current to a respective estimated voltage of the energy storage cell, determine a maximum electrical charge current or a maximum electrical discharge current of the energy storage cell corresponding to the voltage difference, wherein the respective estimated voltage of the energy storage cell is less than or equal to the upper voltage limit during the time horizon in the case of an electrical charge current, or larger than or equal to the lower voltage limit during the time horizon in the case of an electrical discharge current, wherein the control unit is further configured to, (e) receive a request for a demanded electrical charge current or a demanded electrical discharge current for the energy storage cell; (f) in response to the demanded electrical charge current being larger than the maximum electrical charge current, automatically limit a current delivered to the energy storage cell to the maximum electrical charge current; and (g) in response to the demanded electrical discharge current being larger than the maximum electrical discharge current, automatically limit a current withdrawn from the energy storage cell to the maximum electrical discharge current; wherein the maximum electrical charge current or maximum electrical discharge current (imax;
imin) is given by; - View Dependent Claims (11, 12, 13)
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Specification