JP3526766B2 - Function test method and function test circuit for overcharge protection circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery such as a lithium ion or nickel cadmium battery or a battery pack formed by connecting these secondary batteries in series, and shuts off the charging current when overcharge is detected during charging. The present invention relates to a method for inspecting whether or not the function of an overcharge protection circuit for protecting a battery operates normally, and a function inspection circuit used in the method.

[0002]

2. Description of the Related Art Electronic devices such as a camera-integrated video tape recorder and a portable compact disc player are
A battery pack in which secondary batteries such as lithium-ion and nickel-cadmium are connected in series is incorporated as a driving power source, and an overcharge protection circuit is incorporated in or attached to the battery pack. This overcharge protection circuit detects when one of the secondary batteries is in the overcharge state while charging the secondary battery of the battery pack with the charger and supplies the charging current to each battery. By shutting off, the battery is prevented from being damaged.

The above-mentioned overcharge protection circuit cannot prevent damage to the battery when it does not operate normally based on the detection of the overcharged state of the battery. So, in the past,
A first protection function unit that cuts off the supply of charging current to the battery in a recoverable state by operating upon detection of overcharge of the battery;
If the first protection function unit does not operate normally, the second protection function unit having an extremely high safety that can be surely cut off in the state where the first protection function unit is not activated and cannot be restored, is provided.
An overcharge protection circuit has been proposed that can reliably protect a battery by providing this double protection function. Second above
The protection function unit of detects that the terminal voltage of the battery further rises because the first protection function unit does not operate,
For example, a non-reciprocal safety element such as a thermal fuse is controlled so that a current capable of melting and interrupting the element is applied. Generally, in this overcharge protection circuit, the first protection function unit operates by detecting the overdischarge of the battery to cut off the discharge current of the battery, or the second protection function unit causes an excessive discharge due to some cause. It also has an over-discharge protection function that shuts off the discharge current by detecting the flow of current and melting and blocking the irreversible safety element.

By the way, the above-mentioned overcharge protection circuit is inspected at the time of shipping to confirm whether or not it operates normally. In the inspection of this functional operation, especially when the second protection function section is actually operated by detecting the generated voltage by the voltage generating means connected for inspection instead of the battery, the irreversible safety element is melted and cut off. It is not preferable because it will be impossible to recover. Therefore, for example, when a thermal fuse with a resistor that melts and cuts off when the temperature rises to a predetermined temperature due to heat generation due to the current flowing through the resistor is used as the non-reversible safety element,
Control the time and timing of current flow to the non-reciprocal safety element so that the inspection of the second protective function section can be repeated as many times as the number of secondary batteries mounted without melting and blocking the non-reciprocal safety element. is doing.

That is, the characteristic curve shown by the chain double-dashed line in FIG. 4 shows the non-reciprocal safety element when the inspection of the second protective function portion is repeated a number of times corresponding to the number of batteries in the conventional functional inspection. It shows the temperature change. As is apparent from this, when inspecting the functional operation of the second protection function unit, when performing the inspection corresponding to each secondary battery, the current supply to the resistor-equipped temperature fuse is prevented from melting at a predetermined temperature. It stops before reaching, then waits for the temperature of the thermal fuse to drop without passing current, and shifts to the inspection corresponding to the next secondary battery.

[0006]

However, the irreversible safety element is
Since this current repeatedly flows as many times as the number of batteries mounted in the battery pack, it is greatly damaged. Also,
When the non-reciprocal safety element is a thermal fuse with resistance, this thermal fuse generally melts and cuts off when a current flows for a time of about 2 to 3 seconds, so the time when the current flows corresponds to each secondary battery. It is set to about 1 second per inspection. However, since a waiting time until cooling is required for each inspection corresponding to each battery, an inspection time corresponding to one battery is eventually required to be about 2 to 3 seconds, and the same number of times as the number of the attached batteries is required. If the inspection is repeated, the entire inspection time will be considerably long.

In addition, although the inspection corresponding to each of the above-mentioned batteries is generally performed continuously by sequence control, if the waiting time is set to the time required for the thermal fuse to completely cool, it is generally long. It will be the inspection time. Therefore, since the standby time cannot be set sufficiently long, the thermal fuse is shifted to the next inspection without being completely cooled, and as shown by the temperature characteristics shown by the chain double-dashed line in FIG. The temperature at the start gradually rises as the inspection is repeated, and eventually the thermal fuse may melt and cut off.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and the function test of the overcharge protection circuit capable of surely checking the function operation without damaging the non-reciprocal safety element. It is an object to provide a method and a function test circuit.

[0009]

In order to achieve the above object, a first aspect of the present invention measures a voltage of a secondary battery during charging and regulates the measured voltage to correspond to overcharge of the secondary battery. By a protection function unit that outputs a charge abnormality detection signal when the voltage exceeds a voltage value, a current amplification circuit unit that amplifies the current by receiving the charge abnormality detection signal, and by supplying the current amplified by this current amplification circuit unit In a method of inspecting a functional operation of an overcharge protection circuit having a non-reciprocal safety element that melts and cuts off a charging current to a secondary battery, the current amplification circuit unit comprises:
As a test state in which the charging abnormality detection signal does not operate regardless of whether or not the charging abnormality detection signal is supplied, a voltage corresponding to overcharge is generated at the mounting terminal portion of the secondary battery, and the charging abnormality is detected by measuring the voltage of the output signal of the protection function unit. Whether or not the detection signal is output is detected, and whether the functional operation of the protection function unit is correct or not is determined based on the detection result.

In this method of checking the function of the overcharge protection circuit,
Since the current amplification circuit section is inspected after receiving the charging abnormality detection signal from the protection function section and setting it in the inspection state in which current amplification is not performed, the non-reciprocal safety element does not flow any current during the inspection process. Doesn't take damage.
Further, the voltage of the output signal of the protection function unit is measured, and if the measured voltage is a voltage corresponding to the charging abnormality detection signal, it can be determined that the protection function unit has normally operated.

According to a second aspect of the present invention, the voltage of each of the plurality of secondary batteries contained in the battery pack is individually measured during charging, and the measured voltage of at least one secondary battery corresponds to overcharge. The protection function unit that outputs the charging abnormality detection signal when the voltage exceeds the regulation voltage value, the current amplification circuit unit that amplifies the current by receiving the charging abnormality detection signal, and the current amplified by the current amplification circuit unit. In a method of inspecting the functional operation of an overcharge protection circuit that has an irreversible safety element that cuts off the charging current to each secondary battery by melting when supplied, overcharging the respective mounting terminals of each secondary battery. Voltage is sequentially generated, the current amplification circuit section is set to a test state in which the current amplification circuit section does not perform current amplification operation even when supplied with the charging abnormality detection signal, and then the voltage is measured by the output signal of the protection function section. Charge abnormality detection The presence or absence of a signal output is detected, and whether the functional operation of the protection function unit is correct or not is determined based on the detection result, and the inspection state of the current amplification circuit at the time of inspecting at least a specific one of the secondary batteries. The current amplification circuit section and the non-reciprocal safety element while supplying a current that does not melt to the non-reciprocal safety element by the operation of the current amplification circuit by the supply of the charging abnormality detection signal. The voltage at the connection point is measured, and whether the functional operations of the protection function unit and the non-reciprocal safety element are correct or not is determined based on the measured voltage.

In the method of checking the function of the overcharge protection circuit,
When continuously performing inspections corresponding to the mounting parts of multiple secondary batteries built into the battery pack by sequence control,
The current amplification circuit section is set to a test state where current amplification is not performed even if a charge abnormality detection signal is received from the protection function section, then the voltage of the output signal of the protection function section is measured and the measured voltage corresponds to the charge abnormality detection signal. If the voltage is within the range, it can be determined that the protection function unit has operated normally. At this time, since the non-reciprocal safety element has the operation of the current amplification circuit section blocked,
No current flows, so no damage will occur.

Further, the inspection state of the current amplification circuit is released only for the inspection corresponding to a specific secondary battery among a plurality of batteries, and the current amplification circuit unit is operated by the charging abnormality detection signal from the protection function unit to make the non-operation. While supplying a current that does not melt down to the reversible safety element, the voltage at the connection point between the current amplification circuit section and the nonreciprocal safety element is measured, so if the measured voltage is a constant voltage value, It can be determined that both the protection function unit and the current amplification circuit unit have normally operated. On the other hand, when the measured voltage is 0 V, no current flows from the current amplification circuit unit to the non-reciprocal safety element. It can be determined that at least one of the protection function unit and the current amplification circuit unit did not operate normally. That is, not only the protection function section but also the current amplification circuit section can be inspected.

Moreover, since the non-reciprocal safety element only flows a current that does not melt and shut off only at the time of inspection corresponding to at least one specific secondary battery, the temperature may rise to the state of melt and shut off. No, maintain that temperature after cooling. Therefore, it is not necessary to set the waiting time until the temperature of the non-reciprocal safety element is lowered in a series of inspection steps by sequence control for all of the plurality of secondary batteries, and therefore a large number of secondary batteries are built in. Even with a battery pack, all inspections can be performed in a short time.

A third aspect of the present invention measures the voltage of a secondary battery during charging and outputs a charge abnormality detection signal when the measured voltage exceeds a regulated voltage value corresponding to overcharge of the secondary battery. Protection function section, a current amplification circuit section having an FET that amplifies the current in response to the charging abnormality detection signal, and a current amplified by the current amplification circuit section is supplied to melt and blow to the secondary battery. A battery capable of generating a voltage corresponding to overcharge at a mounting terminal portion of a secondary battery in a function inspection circuit for inspecting a functional operation of an overcharge protection circuit having an irreversible safety element that cuts off a charging current For the FET having a gate connected to the control signal output terminal of the protection function unit, a test diode is connected in the forward direction from the source to the gate, and the gate and the control signal output are connected. To the connection point of the child has a configuration of connecting the first voltage measuring unit.

In the function inspection circuit of this overcharge protection circuit,
The source-gate voltage of the FET that constitutes the current amplification circuit section becomes the forward voltage of the inspection diode, and this forward voltage is smaller than the threshold voltage of the FET. Even if a detection signal is input, it cannot shift to the conductive state.
Therefore, the function inspection method for the overcharge protection circuit according to the first aspect of the invention can be embodied with a simple configuration, and the same effect can be reliably obtained.

According to a fourth aspect of the present invention, the voltage of each of the plurality of secondary batteries contained in the battery pack during charging is measured, and the measured voltage of at least one of the secondary batteries is the secondary battery's excess voltage. A protection function unit that outputs a charge abnormality detection signal when the voltage exceeds a regulated voltage value equivalent to charging, a current amplification circuit unit that amplifies current by receiving the charge abnormality detection signal, and is amplified by the current amplification circuit unit. In the function inspection circuit of the overcharge protection circuit, which has an irreversible safety element that melts and cuts off the charging current to each secondary battery by supplying the A battery voltage generator capable of generating a voltage corresponding to charging is individually connected, and a gate is connected to the source and the gate of the FET having the control signal output terminal of the protection function unit connected to the gate, A test diode arranged in the forward direction and a switching element that is turned on / off by an external signal are connected in series, and at the connection point between the gate and the control signal output terminal, a voltage is applied when the switching element is turned on. The first voltage measuring unit to be measured is connected to the FET
A second voltage measuring unit for measuring a voltage when the switching element is turned off is connected to a connection point between the drain and the irreversible safety element.

In the function inspection circuit of this overcharge protection circuit,
The inspection diode can be electrically disconnected from the circuit by turning off the switching element only during the inspection corresponding to the specific secondary battery, and the inspection corresponding to all the secondary batteries can be performed without any trouble by the sequence control. Therefore, the function inspection method for the overcharge protection circuit according to the second aspect of the invention can be embodied with a simple configuration, and the same effect can be reliably obtained.

In the above-mentioned function inspection circuit of the overcharge protection circuit, a switching element is provided in the battery voltage generation section corresponding to at least a specific secondary battery among a plurality of cells when the generation of the voltage corresponding to the overcharge is detected. It is preferable to provide a configuration in which a voltage detection unit that outputs a control signal to turn off is connected. Accordingly, with a simple configuration, the switching element can be surely turned off only at the time of the inspection corresponding to the specific battery.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block connection diagram showing a battery pack 1 having a built-in overcharge protection circuit which is an inspection object of the present invention. This battery pack 1 has a rated voltage of 3.6 V, for example, by connecting a plurality of secondary batteries Ba1 to Ba3 (three batteries are illustrated in the figure) in series, so that the voltage of 3.6 V required for driving an electronic device can be reduced. A high required voltage is obtained between the positive and negative charging / discharging terminals 2 and 3. Therefore, when this battery pack 1 is attached to an electronic device, the charging / discharging terminals 2 and 3 are connected to the corresponding terminals of the electronic device, and the secondary batteries Ba1 to Ba3 are connected to the electronic device via the charging / discharging terminals 2 and 3. Power is supplied.

The overcharge protection circuit to be inspected according to the present invention includes the first and second protection function sections 4 and 5, the overcharge prevention switch 8, the overdischarge prevention switch 9, the load resistance 10 and the FE.
It is composed of a current amplification circuit unit 23 made of T11 and a temperature fuse 12 with a resistance which is a kind of non-reciprocal safety element. This overcharge protection circuit is used when charging the secondary batteries Ba1 to Ba3 of the battery pack 1. The secondary batteries Ba1 to Ba3 are protected from overcharging. Next, the operation of the overcharge protection circuit will be described below.

When charging the secondary batteries Ba1 to Ba3, the charging / discharging terminals 2 and 3 are connected to predetermined terminals of the charger. At this time, the first protection function part 4 and the second protection function part 5 are respectively connected to the first to fourth measurement terminals T1.
The terminal voltage of each of the secondary batteries Ba1 to Ba3 is measured through T4. The first protection function unit 4 includes a regulated voltage value for detecting overcharge of the secondary batteries Ba1 to Ba3, for example, 4.3 when the rated voltage of each of the secondary batteries Ba1 to Ba3 is 3.6V. The regulated voltage value of V is set in advance.

The internal structure of the first protection function unit 4 is not shown, but each two adjacent measuring terminals T1 to T4.
The voltage measurement circuit that individually measures the terminal voltage of each of the secondary batteries Ba1 to Ba3, and when the measured voltage of this voltage measurement circuit exceeds the regulated voltage value of 4.3 V corresponding to overcharge, A comparison circuit that outputs a charge detection signal,
It is configured to have an OR circuit that outputs a charge abnormality detection signal from the first control signal output terminal O1 when at least one of the secondary batteries Ba1 to Ba3 is overcharged.

The overcharge prevention switch 8 which is a reversible switch composed of an FET is brought into a non-conducting state by the charging abnormality detection signal output from the first control signal output terminal O1,
Cut off the charging current from the charger. The first protection function unit 4 also has an over-discharge protection function, and when the terminal voltage of at least one of the secondary batteries Ba1 to Ba3 drops below a preset limit voltage value. A discharge abnormality detection signal is output from the second control signal output terminal O2 to make the overdischarge prevention switch 9 which is a reversible switch composed of an FET non-conductive to cut off the discharge current to the electronic device.

The second protection function unit 5 operates when the first protection function unit 4 does not operate normally due to some abnormality, and the secondary batteries Ba1 to Ba3 are in a dangerous state due to overcharge. To prevent this. The second protection function unit 5 includes a regulated voltage value for detecting overcharge of the secondary batteries Ba1 to Ba3, for example, each secondary battery B.
When the rated voltage of a1 to Ba3 is 3.6 V, the regulated voltage value of 4.5 V is preset.

The second protection function part 5 is, like the first protection function part 4, two adjacent measuring terminals T1 to T4.
The voltage measurement circuit that individually measures the terminal voltage of each of the secondary batteries Ba1 to Ba3, and when the measured voltage of this voltage measurement circuit exceeds the regulated voltage value of 4.5 V corresponding to overcharge, A comparison circuit that outputs a charge detection signal,
It is configured to have an OR circuit that outputs a charge abnormality detection signal from the control signal output terminal O when at least one of the secondary batteries Ba1 to Ba3 is overcharged.

When the first protection function unit 4 is operating normally, the charging current is cut off when the terminal voltage of any of the secondary batteries Ba1 to Ba3 rises to 4.3 V or more. However, when the first protection function unit 4 does not operate normally, the charging current is continuously supplied to each of the secondary batteries Ba1 to Ba3, and the terminal voltage thereof rises to 4.3 V or more. The terminal voltage is the regulated voltage value of the second protection function unit 4.5.
When the voltage rises above V, the charge abnormality detection signal is output from the control signal output terminal O through the load resistor 10 and supplied to the gate G of the FET 11 forming the current amplification circuit section 23.

In this embodiment, as the FET 11,
The case where a P-channel depletion MOS type FET is used is shown as an example. This FET 11 is in a non-conducting state in which no current flows between the source S and the drain D when a voltage is applied to the gate G, and the voltage is applied to the gate G. When no voltage is applied, that is, when the gate voltage is 0 V, the amplified drain current flows.

Therefore, any of the secondary batteries Ba1 to Ba
In the normal state where 3 is also a normal terminal voltage, the normal charge detection signal which is the positive constant voltage Vcc is applied to the gate G of the FET 11 from the control signal output terminal O of the second protection function unit 5,
The FET 11 maintains the non-conducting state in which the drain current does not flow. On the other hand, when the second protection function unit 5 detects that the terminal voltage of at least one of the secondary batteries Ba1 to Ba3 has risen to the regulated voltage value of 4.5 V or more, it is 0 V or 0 V.
A very small charge abnormality detection signal close to
Since it is output to the gate G, the FET 11 becomes conductive and the drain current increases. The amplified current flows through the resistance of the resistance-equipped thermal fuse 12, so that in the resistance-equipped thermal fuse 12, the resistance heats up due to the flow of current, and the temperature of the fuse portion thermally connected to the resistance rises to a predetermined temperature. At this point, the melt current is cut off, and the charging current is completely cut off. As the non-reciprocal safety element, a thermal fuse that melts and cuts off when a current of a certain value or more flows through itself can be used in addition to the thermal fuse with resistance 12.

FIG. 2 is a block connection diagram embodying the function inspection method of the overcharge protection circuit according to the first embodiment of the present invention. In FIG. 2, the second protection which is the gist of the present invention is shown. A configuration for performing a function inspection of the functional unit 5 is shown. That is,
FET for current amplification in the overcharge protection circuit built in or attached to the battery pack 1 shown in FIG.
11, the inspection diode 13 is connected in the forward direction from the source S to the gate G, and the first voltage measurement unit 1 is connected to the connection point between the gate G and the cathode of the inspection diode 13.
4 are connected. Further, at both ends of each of the secondary batteries Ba1 to Ba3, both ends of a battery voltage generating unit 22 for function inspection having a variable power source E, a backflow prevention diode DO, and a voltage generating resistor R3 are respectively provided. Individual protection resistor R
1 and R2 are connected. In addition, when the secondary batteries Ba1 to Ba3 are not mounted in the battery mounting portion of the battery pack 1, the battery voltage generator 2 is connected to both terminals of each battery mounting portion.
2 may be directly connected without the protection resistors R1 and R2.

Next, a function inspection method of the overcharge protection circuit based on the above configuration will be described.

The functional inspection in this embodiment is FE
When the operation of the current amplification circuit section 23 composed of T11 is confident, only the functional operation of the second protection function section 5 is inspected, and the function inspection is based on sequence control by a controller (not shown). It is done continuously.

That is, the controller controls each secondary battery B
The terminal voltages of the battery voltage generators 22 corresponding to a1 to Ba3 are the regulated voltage values of the first protection function unit 4 in sequence.
The variable power sources E are sequentially controlled to be 4.3 V or more, and the first control signal of the first protection function unit 4 is generated at the timing when the terminal voltage of each battery voltage generation unit 22 becomes the above regulated voltage value or more. Although it is inspected whether or not the charging abnormality detection signal is output from the output terminal O1, the functional inspection of the first protection function unit 4 is not the gist of the present invention, and thus detailed description thereof will be omitted.

Subsequently, the controller controls each secondary battery Ba.
The terminal voltages of the battery voltage generators 22 individually corresponding to 1 to Ba3 are the regulated voltage values of the second protection function unit 5 in sequence 4.
The variable power sources E are sequentially controlled to be 5 V or higher, and the control signal output terminal O of the second protection function unit 5 is controlled at the timing when the terminal voltage of each battery voltage generation unit 22 becomes equal to or higher than the above regulated voltage value. It is determined whether or not the charging abnormality detection signal is output from. After that, the function inspection of the first and second protection function units 4 and 5 due to over-discharge is performed by the same means as described above, but this inspection is not the gist of the present invention, so the detailed description will be omitted. First, the inspection of the functional operation of the second protection function unit 5 due to overcharge will be described below.

The controller is used for each of the secondary batteries Ba1 to Ba.
The terminal voltage of the battery voltage generator 22 corresponding to No. 3 is sequentially set to 4.5 V or more which is the regulated voltage value of the second protection function unit 5 by the variable control of the variable power source E, and at the same time, the first voltage is set at the set timing. Sequence control is performed so as to determine the measured voltage of the voltage measuring unit 14. This first voltage measuring unit 1
When the measured voltage of 4 has the same value as the above-mentioned positive constant voltage _Vcc , it means that the second protection function unit 5 did not operate normally. That is, in the second protection function unit 5, the terminal voltage of each battery voltage generation unit 22 is 4.5 V which is the regulated voltage value.
Despite the above, the positive constant voltage _Vcc , which is the normal charge detection voltage signal, is erroneously output. Here, the FET 11 is a measurement voltage of the first voltage measurement unit 14,
That is, the voltage applied to the gate G is a positive constant voltage V
_{Since cc} is a voltage value equal to or higher than the threshold voltage, the non-conduction state is maintained. As a result, the resistor-equipped thermal fuse 12 is not damaged because no current flows at all.

On the other hand, when the measured voltage of the first voltage measuring unit 14 is lower than the voltage value V _cc of the charge normal detection signal by 0.6 V which is the forward voltage of the inspection diode 13, This means that the second protection function unit 5 has operated normally. That is, the second protection function unit 5 outputs a charging abnormality detection signal of approximately 0 V when the battery voltage generation unit 22 detects that a voltage of 4.5 V or more, which is the regulated voltage value, is generated. Since this voltage causes the inspection diode 13 to be turned on, the voltage between the source S and the gate G of the FET 11 becomes 0.6 V which is the forward voltage of the diode 13. Therefore, the FET 11 is connected between the source S and the gate G.
Since the voltage of 0.6 V is applied, the current is limited, and even though the charging abnormality detection signal of approximately 0 V is supplied to the gate G, the state cannot be switched to the conductive state.

Therefore, the measured voltage of the first voltage measuring section 14, that is, the gate voltage of the FET 11 is lower than the voltage value V _cc of the charge normal detection signal by 0.6 V which is the forward voltage of the inspection diode 13. , This voltage is FET
Since it is higher than the threshold voltage of 11, FET
11 holds the non-conduction state. As a result, the resistor-equipped thermal fuse 12 is not damaged because no current flows at all as in the above case.

FIG. 3 is a block connection diagram embodying the function inspection method of the overcharge protection circuit according to the second embodiment of the present invention. In FIG. 3, the second protection which is the gist of the present invention is shown. Only the configuration for performing the function inspection of the functional unit 5 is shown. That is, in addition to the configuration of FIG. 2 embodying the function inspection method according to the first embodiment, the phototransistor 18 of the photocoupler 17 is interposed between the cathode of the inspection diode 13 and the gate G of the FET 11. Plug and connect, voltage detection unit 21
Is connected so that the voltage generated by the battery voltage generator 22 corresponding to the specified specific secondary battery Ba1 can be detected, and the light emitting diode 19 of the photocoupler 17 is based on the result of the voltage detection by the voltage detector 21. The second voltage measuring unit 20 is configured so as to control the supply current, and further, at the connection point between the drain D of the FET 11 and the temperature fuse with resistance 12.
It is attached with the configuration that is connected. Other configurations are the same as those in FIG.

Next, a function inspection method of the overcharge protection circuit based on the above configuration will be described.

The function test in this embodiment is the second
In addition to the inspection of the functional operation of the protection function unit 5, the inspection of the functional operation of the current amplification circuit unit 23 including the FET 11 is also performed in series based on the sequence control. That is,
In the controller, as in the case of the first embodiment, the terminal voltages of the battery voltage generators 22 individually corresponding to the secondary batteries Ba1 to Ba3 are sequentially regulated voltage values of the second protection function unit 5. Each of the variable power sources E is controlled in order so that the voltage becomes 4.5 V or more, and the terminal voltage of the battery voltage generator 22 corresponding to the specific secondary battery Ba1 designated by the connection of the voltage detector 21 is the regulated voltage value. Only at the timing set as described above, both the functional operation of the second protection function section 5 and the functional operation of the current amplification circuit section 23 including the FET 11 are inspected from the measured voltage of the second voltage measurement section 20, and other Based on the measured voltage of the second voltage measuring unit 20 at the timing when the terminal voltage of the battery voltage generating unit 22 corresponding to the secondary batteries Ba2 and Ba3 becomes equal to or higher than the regulation voltage value, as in the first embodiment. Second protector Only the functional operation of the Noh department 5 is inspected.

In this embodiment, first, the terminal voltage of the battery voltage generator 22 corresponding to the specified specific secondary battery Ba1 is changed to the regulated voltage of the second protection function unit 5 by the variable control of the variable power source E. At the same time as setting the value to 4.5 V or more, only the measured voltage of the second voltage measuring unit 20 is determined at the set timing. When the measured voltage of the second voltage measuring unit 20 is 0V, the second protection function unit 5
Alternatively, it can be determined that at least one of the FETs 11 does not operate normally, and if the measured voltage has a positive constant voltage value V _cc , it is determined that both the second protection function unit 5 and the FET 11 have operated normally. it can. Here, the drain current flows only to such an extent that the temperature fuse with resistance 12 does not melt and cut off, and this current value is set by the output time of the control signal from the voltage detection unit 21, that is, the off time of the inspection diode 13. .

That is, the voltage detecting section 21 supplies a current to the light emitting diode 19 of the photocoupler 17 to keep the phototransistor 18 in the ON state in a normal state, and the inspection diode 13 controls the second protection function section 5. 2 is connected to the connection point between the signal output terminal O and the gate G of the FET 11.
However, when a voltage value equal to or higher than the regulated voltage value of 4.5 V generated in the battery voltage generation unit 22 corresponding to the specific secondary battery Ba1 is detected, the light emitting diode 19
To stop the current supply to. Therefore, the inspection diode 13 is separated from the circuit, and the FET
The operation of 11 and the protection of the temperature fuse with resistance 12 are released. Therefore, if the second protection function unit 5 detects a voltage of 4.5 V or more generated in the battery voltage generation unit 22 corresponding to the specific secondary battery Ba1 and outputs a charge abnormality detection signal having a voltage value of 0 V, , The FET 11 becomes conductive, and the current-amplified drain current flows to the temperature fuse with resistance 12. Therefore, the voltage measured by the second voltage measuring unit 20 becomes a positive constant voltage value V _cc .

On the other hand, whether the second protection function unit 5 did not output the 0V charging abnormality detection signal while detecting the voltage of 4.5V or more, or the FET 11 supplies the 0V charging abnormality detection signal to the gate G. However, if the conductive voltage is not turned on, the measured voltage of the second voltage measurement unit 20 is 0 because the FET 11 is not turned on in any of the above cases.
It becomes V. As a result, when the measured voltage of the second voltage measuring unit 20 has a positive constant voltage value _Vcc , it can be determined that the second protection function unit 5 and the FET 11 have both functioned normally, and the measured voltage Is 0 V, it can be determined that at least one of the second protection function unit 5 and the FET 11 does not function normally.

The terminal voltage of the battery voltage generator 22 corresponding to the secondary battery Ba2 is set to 4.5 V or more, which is the regulated voltage value of the second protection function unit 5 by the variable control of the variable power source E, and at the same time, Only the measured voltage of the first voltage measuring unit 14 is determined at the set timing. At this point,
Since the generated voltage of the battery voltage generator 22 corresponding to the specific secondary battery VBa1 detected by the voltage detector 21 is variably controlled to 4.5 V or less, the voltage detector 21 detects the voltage and detects the light emitting diode 19 Current is supplied to the phototransistor 18 so that the phototransistor 18 is turned on and the inspection diode 13 is circuit-connected, and the circuit configuration is the same as that of the first embodiment shown in FIG. In this state, the functional operation of the second protection function unit 5 is determined based on the measured voltage of the first voltage measurement unit 14 as in the second embodiment.

That is, when the measured voltage of the first voltage measuring unit 14 is the positive constant voltage value V _cc , it means that the second protection function unit 5 does not operate normally. When the voltage measured by the first voltage measuring unit 14 is lower than the positive constant voltage value V _{cc by} 0.6 V which is the forward voltage of the inspection diode 13, the second protection function unit 5 Has functioned normally.

Therefore, the controller makes the following judgment based on the above-mentioned respective judgment results. That is, when it is determined that the inspection corresponding to the specific secondary battery Ba1 is normal, the second protection function unit 5 and the FET 1 are
When it is determined that both functional operations of No. 1 are normal and an abnormality occurs in the inspection corresponding to the other secondary batteries Ba2, Ba3, only the abnormal circuit in the second protection function unit 5 is defective. It is determined that On the other hand, a specific secondary battery B
If the inspection corresponding to a1 is determined to be abnormal,
When it is determined that at least one test result of the tests corresponding to the other secondary batteries Ba2 and Ba3 is normal,
When it is determined that the functional operation of the FET 11 is not normal and all the inspection results corresponding to the other secondary batteries Ba2 and Ba3 are abnormal, it is determined that the second protection function unit 5 is defective. .

In the function inspection method according to the second embodiment, the current is passed through the temperature fuse with resistance 12 only at the time of the inspection corresponding to the specific secondary battery Ba, but it corresponds to the other secondary batteries Ba2 and Ba3. At the time of shifting to the inspection, the voltage detection unit 21 turns on the photocoupler 17 to connect the inspection diode 13 between the source S and the gate G of the FET 11, so that the connected inspection diode 13 is connected.
Therefore, the FET 11 is prevented from becoming conductive, and no current flows through the temperature fuse with resistance 12. Therefore, in the temperature fuse with resistor 12, in a series of inspection steps by sequence control for all the secondary batteries Ba1 to Ba3, current flows only during the inspection corresponding to one specific secondary battery Ba1 and is melted. Since the output time of the control signal of the voltage detection unit 21 is set so that a current not to be cut off will flow, the temperature does not rise to the melting cutoff state as shown by the characteristic curve shown by the solid line in FIG. After that, keep the temperature. Also,
Since it is not necessary to set the waiting time until the temperature of the thermal fuse with resistance 12 decreases, a large number of secondary batteries Ba1
Even with the battery pack 1 including the to Ba3, all the inspections can be performed in a short time.

[0048]

As described above, according to the function inspection method for the overcharge protection circuit of the first aspect of the invention, the current amplification circuit section is inspected without receiving the charge abnormality detection signal from the protection function section and not amplifying the current only during the inspection. Since I made it into a state and inspected it,
The irreversible safety element is not damaged because no current flows in the inspection process. Since the voltage of the output signal of the protection function unit is measured, if the measured voltage is the voltage corresponding to the charge abnormality detection signal,
It can be determined that the protection function unit has operated normally.

According to the function inspection method for the overcharge protection circuit of the second invention, the inspection state of the current amplification circuit is released only for the inspection corresponding to the specific secondary battery among the plurality of the secondary battery, and the protection function unit is activated. Measure the voltage at the connection point between the current amplification circuit section and the non-reciprocal safety element while operating the current amplification circuit section according to the charging abnormality detection signal and supplying a current that does not melt to the non-reciprocal safety element. Therefore, not only the protection function section but also the current amplification circuit section can be inspected. In addition, the non-reciprocal safety element only flows a current that does not melt and shut off only at the time of inspection corresponding to at least one specific secondary battery, so that the temperature does not rise to the state of melt and shut off. Further, when performing a series of inspection steps by sequence control for all of the plurality of secondary batteries,
Since it is not necessary to set the waiting time until the temperature of the non-reciprocal safety element decreases, all the tests can be performed in a short time even with a battery pack having many secondary batteries built therein.

According to the function inspection circuit of the overcharge protection circuit of the third invention, with respect to the FET constituting the current amplification circuit portion,
Since the inspection diode is connected in the forward direction from the source to the gate, the source-gate voltage becomes the forward voltage of the inspection diode that is smaller than the threshold voltage, so that the FET changes from the protection function section to the gate. Even if the charging abnormality detection signal is input, it is not possible to shift to the conductive state. Therefore, the function inspection method for the overcharge protection circuit according to the first aspect of the invention can be embodied with a simple configuration, and the same effect can be reliably obtained.

According to the function inspection circuit of the overcharge protection circuit of the fourth invention, the inspection diode and the switching element which is turned on / off by the external signal are connected in series between the source and the gate of the FET. The inspection diode can be electrically disconnected from the circuit by turning off the switching element only during the inspection corresponding to the specific secondary battery, and the inspection corresponding to all the secondary batteries can be performed without any trouble by the sequence control. Therefore, the function inspection method for the overcharge protection circuit according to the second aspect of the invention can be embodied with a simple configuration, and the same effect can be reliably obtained.

[Brief description of drawings]

FIG. 1 is a block connection diagram showing a battery pack including a charge protection circuit which is an inspection target of the present invention.

FIG. 2 is a block connection diagram embodying the function inspection method for the charge protection circuit according to the first embodiment of the present invention.

FIG. 3 is a block connection diagram embodying a function inspection method for a charge protection circuit according to a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a temperature change with time of a thermal fuse with a resistor, which is a non-reciprocal safety element, in the function inspection method of the present invention and the conventional overcharge protection circuit.

[Explanation of symbols]

1 battery pack 5 Second protection function part (protection function part) 11 FET 12 Thermal fuse with resistance (non-reversible safety element) 14 First voltage measuring unit 17 Photo coupler (switching element) 20 Second voltage measuring unit 21 Voltage detector 22 Battery voltage generator 23 Current amplifier circuit Ba1 to Ba3 secondary batteries O control signal output terminal

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yoshichika Matsumoto, 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP 10-56742 (JP, A) JP 9 -312172 (JP, A) JP 10-51962 (JP, A) JP 8-116627 (JP, A) JP 7-227045 (JP, A) JP 8-205516 (JP, A) ) JP 2000-50506 (JP, A) JP 11-234910 (JP, A) JP 11-98701 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02J 7/00-7/12 H02J 7/34-7/36 H02H 7/18 H01M 10/44

Claims (5)

(57) [Claims] 1. A protection function unit that measures the voltage of a secondary battery during charging and outputs a charge abnormality detection signal when the measured voltage exceeds a regulated voltage value corresponding to overcharge of the secondary battery. And a current amplification circuit section for amplifying the current in response to the charging abnormality detection signal, and an irreversible safety element for cutting off the charging current to the secondary battery by melting due to the supply of the current amplified by the current amplification circuit section. A method of inspecting a functional operation of an overcharge protection circuit, comprising: a rechargeable battery mounting terminal section, wherein the current amplification circuit section is set to an inspection state in which the current amplification circuit section does not operate regardless of whether or not the charging abnormality detection signal is supplied. A voltage corresponding to overcharge is generated, and the presence or absence of the output of the charging abnormality detection signal is detected by measuring the voltage of the output signal of the protection function unit, and whether the functional operation of the protection function unit is correct or not based on the detection result. To determine A method for inspecting the function of an overcharge protection circuit, which is characterized in that 2. A regulated voltage value in which at least one secondary battery among the plurality of secondary batteries contained in the battery pack is individually measured during charging and the measured voltage corresponds to overcharge. When it becomes the above, a protection function unit that outputs a charge abnormality detection signal, a current amplification circuit unit that receives the charge abnormality detection signal and amplifies the current, and blows off by supplying the current amplified by this current amplification circuit unit. It is a method of inspecting the functional operation of an overcharge protection circuit that has a non-reversible safety element that cuts off the charging current to each secondary battery, and is equivalent to overcharging the mounting terminals of each secondary battery. Voltage is sequentially generated, and the current amplification circuit unit is set to a test state in which current amplification does not operate even when the charge abnormality detection signal is supplied, and then the charge abnormality is measured by measuring the voltage of the output signal of the protection function unit. Output of detection signal The presence or absence is detected, and whether the functional operation of the protection function unit is correct or not is determined based on the detection result, and the inspection state of the current amplification circuit is released at the time of inspecting at least one specific one of the secondary batteries. While supplying a current that does not melt to the non-reciprocal safety element by the operation of the current amplifying circuit due to the supply of the charging abnormality detection signal, the connection point between the current amplifier circuit section and the non-reciprocal safety element A method of inspecting a function of an overcharge protection circuit, characterized in that a voltage is measured and whether the functional operation of the protection function section and the non-reciprocal safety element is correct or not is determined based on the measured voltage. 3. A protection function unit that measures the voltage of a secondary battery during charging and outputs a charge abnormality detection signal when the measured voltage exceeds a regulated voltage value corresponding to overcharge of the secondary battery. And an FE that receives the charging abnormality detection signal and amplifies the current
An overcharge protection circuit having a current amplification circuit unit having T and an irreversible safety element that cuts off a charging current to a secondary battery by being melted by being supplied with a current amplified by the current amplification circuit unit Is a function inspection circuit for inspecting the functional operation of the battery, and a battery voltage generator capable of generating a voltage equivalent to overcharge is connected to the mounting terminal of the secondary battery, and the gate controls the protection function. A test diode is connected in a forward direction from the source to the gate of the FET to which the signal output terminal is connected, and a first connection point is formed between the gate and the control signal output terminal.
The function test circuit of the overcharge protection circuit, characterized in that the voltage measurement part of the above is connected. 4. The voltage during charging of each of the plurality of secondary batteries contained in the battery pack is measured, and the measured voltage of at least one of the secondary batteries corresponds to overcharge of the secondary battery. A protection function unit that outputs a charge abnormality detection signal when the voltage exceeds a regulation voltage value, a current amplification circuit unit that amplifies current by receiving the charge abnormality detection signal, and supply of current amplified by this current amplification circuit unit It is a function test circuit of an overcharge protection circuit that has an irreversible safety element that cuts off the charging current to each secondary battery by fusing with, due to overcharging at each mounting terminal of each secondary battery. Battery voltage generators capable of generating a corresponding voltage are individually connected, and a gate is connected to a control signal output terminal of the protection function unit. Forward direction A test diode arranged in series and a switching element that is turned on / off by an external signal are connected in series, and a voltage is measured when the switching element is turned on at a connection point between the gate and the control signal output terminal. And a second voltage measuring section for measuring a voltage when the switching element is off, which is connected to a connection point between the drain of the FET and the non-reciprocal safety element. Functional inspection circuit for protection circuit. 5. A voltage detection unit that outputs a control signal for turning off a switching element to a battery voltage generation unit corresponding to at least a specific secondary battery among a plurality of batteries when the generation of a voltage corresponding to overcharge is detected. The function inspection circuit of the overcharge protection circuit according to claim 4, wherein the overcharge protection circuit is connected.