Deep discharge protection for battery packs with cell groups
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IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
UP-0546836
(2006-10-11)
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등록번호 |
US-7679873
(2010-04-21)
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우선권정보 |
DE-10 2005 000 139(2005-10-13) |
발명자
/ 주소 |
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
0 인용 특허 :
1 |
초록
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A method of preventing deep discharge of the battery pack (1′) with series-connected cell groups (2a, 2b) by polarity reversal of an individual weakest cell (3), includes a difference measurement step which is repeated over time for detecting an event indicative of a probable reversal of pola
A method of preventing deep discharge of the battery pack (1′) with series-connected cell groups (2a, 2b) by polarity reversal of an individual weakest cell (3), includes a difference measurement step which is repeated over time for detecting an event indicative of a probable reversal of polarity in which the change over time of the voltage difference between two cell groups (2a, 2b) having identical numbers of cells is checked to determine if the change in the voltage difference has exceeded an amount corresponding to a difference threshold value which reliably distinguishes a fast polarity reversal of an individual weakest cell (3) in exactly one cell group (2a, 2b) from the slow fluctuation of the voltage difference between two cell groups (2a, 2b) during an ordinary discharge characteristic curve without polarity reversal of an individual weakest cell (3); and a battery pack (1′) and a battery-powered hand-held power tool (7) with a monitoring circuit (5′) for implementing the method.
대표청구항
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What is claimed is: 1. A method of preventing deep discharge of the battery pack (1) with series-connected cell groups (2a, 2b) by polarity reversal of an individual weakest cell (3), comprising a difference measurement step (8) which is repeated over time for detecting an event (Θ) indicativ
What is claimed is: 1. A method of preventing deep discharge of the battery pack (1) with series-connected cell groups (2a, 2b) by polarity reversal of an individual weakest cell (3), comprising a difference measurement step (8) which is repeated over time for detecting an event (Θ) indicative of a probable reversal of polarity and in which a change over time of a voltage difference between two cell groups (2a, 2b) having identical numbers of cells is checked to determine if the change in the voltage difference has exceeded an amount corresponding to a difference threshold value (SD) that reliably distinguishes a fast polarity reversal of an individual weakest cell (3) in exactly one cell group (2a, 2b) from a slow fluctuation of a voltage difference between two cell groups (2a, 2b) during an ordinary discharge characteristic curve without polarity reversal of an individual weakest cell (3). 2. A method according to claim 1, wherein the difference threshold value (SD) lies in the range between 0.5 V and 1.0 V. 3. A method according to claim 1, wherein the difference measurement step (8) is repeated periodically at a difference step interval (T) between 0.1 s and 10 s. 4. A method according to claim 1, wherein a total voltage of the battery pack (1) and/or the group voltages (UI, UII) of the two cell groups (2a, 2b) are/is checked in a further absolute measurement step (11) which is repeated over time for detection of an event (Θ) indicative of a probable reversal of polarity to determine whether the voltage has fallen below an absolute threshold value (SA). 5. A method according to claim 1, wherein the battery pack (1) is electrically disconnected from the consumer in a conditional disconnect step (14) which follows the difference measurement step (8) when the event (Θ) indicating a probable reversal of polarity occurs. 6. A method according to claim 5, wherein the battery pack (1) is electrically disconnected from the consumer in a conditional disconnect step (14) which follows the absolute measurement step (8) when the event (Θ) indicating a probable reversal of polarity occurs. 7. A battery pack, comprising two cell groups (2a, 2b) which are connected in series, each group having an identical quantity of cells (3); and a monitoring circuit (5) arranged in its entirety inside the battery pack for preventing deep discharge of the battery pack (1) with series-connected cell groups (2a, 2b) by polarity reversal of an individual weakest cell (3) by carrying out a difference measurement step (8) which is repeated over time for detecting an event (Θ) indicative of a probable reversal of polarity and in which a change over time of a voltage difference between two cell groups (2a, 2b) having identical numbers of cells is checked to determine if the change in the voltage difference has exceeded an amount corresponding to a difference threshold value (SD) that reliably distinguishes a fast polarity reversal of an individual weakest cell (3) in exactly one cell group (2a, 2b) from a slow fluctuation of a voltage difference between two cell groups (2a, 2b) during an ordinary discharge characteristic curve without polarity reversal of an individual weakest cell (3). 8. A battery pack according to claim 6, wherein a number of cells (3) common to each cell group (2) is between 5 and 20. 9. A battery-powered hand-held power tool, comprising a battery pack (1′) with an average voltage contact (19) which is arranged electrically between two cell groups (2a, 2b) which are connected in series and each have the same number of cells (3); an electric driving motor (20); and a monitoring circuit (5′) for preventing deep discharge of the battery pack (1) with the series-connected cell groups (2a, 2b) by polarity reversal of an individual weakest cell (3), by carrying out a difference measurement step (8) which is repeated over time for detecting an event (Θ) indicative of a probable reversal of polarity and in which a change over time of a voltage difference between two cell groups (2a, 2b) having identical numbers of cells is checked to determine if the change in the voltage difference has exceeded an amount corresponding to a difference threshold value (SD) that reliably distinguishes a fast polarity reversal of an individual weakest cell (3) in exactly one cell group (2a, 2b) from a slow fluctuation of a voltage difference between two cell groups (2a, 2b) during an ordinary discharge characteristic curve without polarity reversal of an individual weakest cell (3), the monitoring circuit (5′) being integrated in its entirety within a motor control of the electric motor (20).
이 특허에 인용된 특허 (1)
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Lowndes Michael W. (Birmingham GB2), Battery monitoring system.
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