US 5,578,915 A · Dynamic battery state-of-charge and capacity determination

Abstract

A battery pack comprising a plurality of series arranged module has a state-of-charge and capacity associated therewith that are determined through dynamic operation thereof including both charge and discharge cycling. Amp*hour integration techniques are used to update state-of-charge until one of the plurality of modules is deeply discharged, at which time state-of-charge is updated in accordance with measured dynamic battery parameters of the deeply discharged module and capacity is updated in accordance with the newly calculated state-of-charge thereby accounting for capacity loss throughout the pack's cycle life. Alternatively, amp*hour integration techniques are used only at relatively high states of charge and dynamic parameter techniques are employed thereafter.

Claims13

Dependent claims

In a rechargeable electrochemical battery system characterized by a series arrangement of multiple electrochemical modules, a method of dynamically determining battery state-of-charge (SOC) comprising the steps of:

determining a minimum module voltage (MINV) from said battery system;
determining a series current (I) through said battery system;
establishing a nominal discharge module threshold voltage (Vth) as a function of said series current (I);
when said series current (I) is outside a predetermined range of current values, determining battery state-of-charge (SOC) as a function of time integrated series current (Qd) and a predetermined battery capacity (Qf);
and
when said series current (I) is within said predetermined range of current values, determining battery state-of-charge (SOC) as one of
a) a function of time integrated series current (Qd) and said predetermined battery capacity (Qf) when said minimum module voltage (MINV) is greater than said nominal discharge module threshold voltage (Vth), and
b) a function of series current (I) and minimum module voltage (MINV) when said minimum module voltage (MINV) is not greater than said nominal discharge module threshold voltage (Vth).

5 more elements

determining a minimum module voltage (MINV) from said battery system;
determining a series current (I) through said battery system;
establishing a first module threshold voltage (vth1) as a function of said series current (I);
establishing a second module threshold voltage (Vth1) as a function of said series current (I);
when said series current (I) is outside a predetermined range of current values, determining battery state-of-charge (SOC) as a function of time integrated series current (Qd) and a predetermined battery capacity (Qf);
and
when said series current (I) is within said predetermined range of current values, determining battery state-of-Charge (SOC) as one of
a) a function of time integrated series current (Qd) and said predetermined battery capacity (Qf) when said minimum module voltage (MINV) is greater than said first module threshold voltage (Vth1),
b) a first function of series current (I) and minimum module voltage (MINV) when said minimum module voltage (MINV) is between said first and second module voltages (Vth1,Vth2), and
c) a second function of series current (I) and minimum module voltage (MINV) when said minimum module voltage (MINV) is not greater than said second module threshold voltage (Vth2).

7 more elements

In a rechargeable electrochemical battery system characterized by a series arrangement of multiple electrochemical modules, an apparatus for dynamically determining battery state-of-charge (SOC) comprising:

means for determining a minimum module voltage (MINV) from said battery system;
means for determining a series current (I) through said battery system;
means for establishing a first module threshold voltage (Vth1) as a function of said series current (I);
means for establishing a second module threshold voltage (Vth2) as a function of said series current (I);
means for determining battery state-of-charge (SOC) as a function of time integrated series current (Qd) and a predetermined battery capacity (Qf) when said series current (I) is outside a predetermined range of current values;
and
means for determining battery state-of-charge (SOC) when said series current (I) is within said predetermined range of current values as one of:
a) a function of time integrated series current (Qd) and said predetermined battery capacity (Qf) when said minimum module voltage (MINV) is greater than said first module threshold voltage (Vth1),
b) a first function of series current (I) and minimum module voltage (MINV) when said minimum module voltage (MINV) is between said first and second module threshold voltages (Vth1,Vth2), and
c) a second function of series current (I) and minimum module voltage (MINV) when said minimum module voltage (MINV) is not greater than said second module threshold voltage (Vth2).

7 more elements

Dependencies are inferred from the claim text.

Dynamic battery state-of-charge and capacity determination

Life of this patent

Dynamic battery state-of-charge and capacity determination

Life of this patent

Abstract

Claims13