US 2007/0164709 A1Published application

Battery pack protection circuit and battery pack

AssigneeMurata Manufacturing Co., Ltd.

InventorsShuji TSUBAKI, Kazuto MIYAGAWA, Yutaka IKEDA

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Abstract

A battery pack includes a first switching element which shuts off a discharging current flowing to a battery cell and a second switching element which shuts off a charging current. A positive temperature coefficient thermistor is inserted between a gate control terminal of a protective control circuit and a gate of at least one of the switching elements, and a resistor is connected between the gate and a source of the switching element. The positive temperature coefficient thermistor is thermally connected to one or more of the first and second switching elements and/or to the battery cell. Thus, an abnormally overheated state of one or more of the switching elements or the battery cell leads to an increase in the resistance of the positive temperature coefficient thermistor causing shut-off of the switching elementthereby protecting the battery pack.

Claims13

Dependent claims

A battery pack protection circuit comprising:

a first switching element which shuts off a discharging current flowing from a battery cell;
a second switching element which shuts off a charging current flowing to the battery cell;
and
a protective control circuit which detects an abnormal state of the voltage, current, or ambient temperature of the battery cell and which controls the first and second switching elements to protect the battery cell from the abnormal state,
further comprising a switching element control circuit including at least one positive temperature coefficient thermistor, the switching element control circuit being thermally connected to at least one of the first switching element, the second switching element, and the battery cell and being inserted into a control signal paths of at least one of the first and second switching elements, so as to shut off the corresponding first or second switching element, on the basis of an increase in the resistance of the positive temperature coefficient thermistor during overheating of the first switching element, the second switching element, or the battery cell.

2 more elements

A battery pack protection circuit comprising:

at least one switching element which has a control terminal, for being connected in series to a positive pole or a negative pole of a battery cell, for being turned off during an abnormality for shutting off a current path for charging/discharging the battery cell;
and
a protective control circuit connected to the control terminal of the at least one switching element such that the at least one switching element can be turned off when an abnormal current flows through the current path, the protective control circuit further having a signal input terminal for receiving a signal showing an abnormal state other than the abnormal current, the at least one switching element being turned off when a signal showing said abnormal state is input to the signal input terminal,
wherein a first positive temperature coefficient thermistor thermally connected to the at least one switching element is further provided, and a signal corresponding to a change in the resistance of the first positive temperature coefficient thermistor due to overheating of the switching element to which the first positive temperature coefficient thermistor is thermally connected is input, as the signal showing the abnormal state, to the signal input terminal.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 11/612,107Filed 18 Dec 2006
Priority: JP 2004-17844016 Jun 2004
Published: 19 Jul 2007
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

H02J 7/663
Including safety or protection arrangements: using battery or load disconnect circuits
H02H 3/085
Responsive to excess current: making use of a thermal sensor, e.g. thermistor, heated by the excess current
H02H 7/18
Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection…:…
H02J 7/62
Including safety or protection arrangements: against overcurrent