Method and apparatus for managing power flow of an electric power storage device
First Claim
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1. Method for managing electric power flow of an electric power storage device adapted to provide power through an electric circuit including an electric machine to crank an internal combustion engine, the method comprising:
- cranking the engine during a first engine cranking event;
after cranking the engine during the first engine cranking event, continually updating an available power from the electric power storage device to crank the engine during a second engine cranking event subsequent to the first engine cranking event based on an initial estimate of an internal resistance of the electric power storage device computed as a function of an open circuit voltage of the electric power storage device, a resistance of the electric circuit, and a minimum voltage of the electric power storage device corresponding to the first engine cranking event;
determining a power threshold required to crank the engine during the second engine cranking event as a function of a lowest ambient temperature corresponding to a predetermined number of engine cranking events preceding the second engine cranking event; and
if the available power is less than the power threshold, taking remedial measures including at least one of reducing power flow out of the electric power storage device and increasing power flow to the electric power storage device.
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Abstract
An electrical power storage device provides power to crank an internal combustion engine. Thereafter available power from the electric power storage device to crank the engine again is continually updated. Remedial measures are invoked if the available power is less than a predetermined power threshold.
14 Citations
11 Claims
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1. Method for managing electric power flow of an electric power storage device adapted to provide power through an electric circuit including an electric machine to crank an internal combustion engine, the method comprising:
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cranking the engine during a first engine cranking event; after cranking the engine during the first engine cranking event, continually updating an available power from the electric power storage device to crank the engine during a second engine cranking event subsequent to the first engine cranking event based on an initial estimate of an internal resistance of the electric power storage device computed as a function of an open circuit voltage of the electric power storage device, a resistance of the electric circuit, and a minimum voltage of the electric power storage device corresponding to the first engine cranking event; determining a power threshold required to crank the engine during the second engine cranking event as a function of a lowest ambient temperature corresponding to a predetermined number of engine cranking events preceding the second engine cranking event; and if the available power is less than the power threshold, taking remedial measures including at least one of reducing power flow out of the electric power storage device and increasing power flow to the electric power storage device.
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2. Method for managing electric power flow of an electric power storage device adapted to provide power through an electric circuit including an electric machine to crank an internal combustion engine, the method comprising:
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cranking the engine during a first engine cranking event; after cranking the engine during the first engine cranking event, continually updating an available power from the electric power storage device to crank the engine-during a second engine cranking event subsequent to the first engine cranking event based on an initial estimate of an internal resistance of the electric power storage device computed as a function of an open circuit voltage of the electric power storage device, a resistance of the electric circuit and a minimum voltage of the electric power storage device corresponding to the first engine cranking event; and if the available power is less than a predetermined cranking power threshold, taking remedial measures including at least one of reducing power flow out of the electric power storage device and increasing power flow to the electric power storage device. - View Dependent Claims (3, 4, 5)
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6. Method for managing electric power flow of an electric power storage device, comprising:
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electrically operatively coupling the electric power storage device to an electric circuit comprising an electric machine adapted to crank an engine; measuring at a first engine crank event an initial open circuit voltage of the electric power storage device, an initial minimum voltage of the electric power storage device, an initial ambient temperature, and an initial temperature of the electric power storage device; determining an initial cranking circuit resistance as a function of the initial ambient temperature; deriving an initial state of charge of the electric power storage device as a function of the initial open circuit voltage of the electric power storage device and the initial temperature of the electric power storage device; computing an initial internal resistance of the electric power storage device as a function of the initial open circuit voltage of the electric power storage device, the initial minimum voltage of the electric power storage device, and the initial cranking circuit resistance; estimating subsequent to the first engine crank event a future state of charge of the electric power storage device expected to occur during a second engine crank event subsequent to the first engine crank event as a function of the initial state of charge of the electric power storage device, estimating a future ambient temperature corresponding to the second engine crank event, and estimating a future temperature of the electric power storage device corresponding to the second engine crank event; determining subsequent to the first engine crank event a future internal resistance of the electric power storage device corresponding to the second engine crank event as a function of the initial internal resistance of the electric power storage device, the initial and future states of charge of the electric power storage device, and the initial and future temperatures of the electric power storage device; estimating subsequent to the first engine crank event a future open circuit voltage of the electric power storage device corresponding to the second engine crank event as a function of the future state of charge of the electric power storage device and the future temperature of the electric power storage device; predicting a maximum cranking power of the electric power storage device available for the second engine crank event as a function of the future open circuit voltage of the electric power storage device, the future internal resistance of the electric power storage device, and a future cranking circuit resistance as a function of the future ambient temperature; comparing the predicted maximum cranking power of the electric power storage device to a predetermined cranking threshold power; and
,controlling the electric power flow of the electric power storage device based upon said comparison. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification