Battery management system with current measurement across on-resistance of semiconductor cutout switch
First Claim
1. A battery management system comprising:
- a battery cell having first and second terminals which form a circuit when connected to powered components;
a semiconductor switch having a first electrode, a second electrode, and a control electrode, the semiconductor switch having an on-resistance between its first and second electrodes and the semiconductor switch located such that its first and second electrodes are in series in the circuit;
means for storing a value corresponding to the on-resistance of the semiconductor switch;
means for measuring the voltage that develops across the first and second electrodes of the semiconductor switch due to current flowing from the battery cell through the semiconductor switch;
means for computing a value of the current flowing through the semiconductor switch based on the measured voltage and the stored on-resistance value; and
means for opening the semiconductor switch by signaling the control electrode of the semiconductor switch if the current flowing through the semiconductor switch is above a threshold value.
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Abstract
An improved battery management circuit and system are disclosed. The improved battery management system relates to the type having at least one battery cell that is connected in a circuit with battery powered components, a current sensing resistance that is located in series within the circuit, voltage measurement circuitry that measures the voltage that develops across the current sensing resistance in proportion to the current flowing through the resistance, a cutout switch that is located in series within the circuit, and means for opening the cutout switch when the measured voltage is too high. The improvement is a single circuit element which functions as the current sensing resistance and as the cutout switch, the single circuit element having first and second electrodes and a control electrode that turns the first and second electrodes "on" and "off" and wherein the current sensing resistance is an on-resistance between the first and second electrodes.
78 Citations
24 Claims
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1. A battery management system comprising:
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a battery cell having first and second terminals which form a circuit when connected to powered components; a semiconductor switch having a first electrode, a second electrode, and a control electrode, the semiconductor switch having an on-resistance between its first and second electrodes and the semiconductor switch located such that its first and second electrodes are in series in the circuit; means for storing a value corresponding to the on-resistance of the semiconductor switch; means for measuring the voltage that develops across the first and second electrodes of the semiconductor switch due to current flowing from the battery cell through the semiconductor switch; means for computing a value of the current flowing through the semiconductor switch based on the measured voltage and the stored on-resistance value; and means for opening the semiconductor switch by signaling the control electrode of the semiconductor switch if the current flowing through the semiconductor switch is above a threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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- 15. An improved battery management system of the type having at least one battery cell that is connected in a circuit with battery powered components, a current sensing resistance that is located in series within the circuit, means for measuring the voltage that develops across the current sensing resistance in proportion to the current flowing through the resistance, a cutout switch that is located in series within the circuit, and means for opening the cutout switch when the measured voltage is too high, the improvement comprising a single circuit element which functions as the current sensing resistance and as the cutout switch, the single circuit element having first and second electrodes and a control electrode that turns the first and second electrodes "on" and "off" and wherein the current sensing resistance is an on-resistance between the first and second electrodes.
Specification