KR102431408B1 - Secondary battery monitoring apparatus and fault diagnosis method - Google Patents

Abstract

(Project) To provide a secondary battery monitoring apparatus and a failure diagnosis method capable of detecting a failure in a circuit for monitoring a secondary battery regardless of a failure point or failure mode.
(Solution Means) A resistor circuit and detection circuit for detecting abnormality in the secondary battery, a current generating circuit for generating a failure detection current for using an output terminal of the resistor circuit as a voltage for failure diagnosis, and failure detection at an output terminal of the resistor circuit It is characterized in that it is provided with a switch for switching the current. Moreover, the fault diagnosis method of the secondary battery monitoring apparatus.

Description

Secondary battery monitoring device and fault diagnosis method

The present invention relates to a secondary battery monitoring apparatus and a failure diagnosis method.

A conventional secondary battery monitoring device for detecting abnormalities in a plurality of series-connected secondary batteries has a function of detecting a failure of the secondary battery monitoring device.

A secondary battery monitoring apparatus is provided with the abnormality detection circuit formed for each secondary battery, and the determination voltage changing circuit which changes the abnormality determination voltage of each abnormality detection circuit. And, in the secondary battery monitoring device, the determination voltage changing circuit changes the abnormality determination voltage of the abnormality detection circuit, and detects the failure of the abnormality detection circuit by detecting the voltage of the secondary battery (for example, refer patent document 1).

Japanese Patent Laid-Open No. 2004-127663

However, in the conventional secondary battery monitoring device, when the value of the reference voltage output by the reference voltage circuit deviates from a failure, a failure in which the determination voltage becomes high in overcharge detection and a failure in which the determination voltage becomes low in overdischarge detection are detected. This was difficult. Moreover, also in the resistance ratio of a voltage division resistance, it was difficult to detect the abnormality depending on the generation|occurrence|production method. That is, the conventional secondary battery monitoring apparatus has a problem in that it is difficult to detect a failure depending on the failure point or failure mode.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a secondary battery monitoring apparatus and a failure diagnosis method capable of detecting a failure regardless of a failure point or failure mode.

A secondary battery monitoring device of the present invention includes a resistance circuit connected to both ends of a secondary battery and outputting a detection voltage from an output terminal, a detection circuit detecting abnormality of the secondary battery based on the detection voltage, and both ends of the secondary battery A voltage-to-current conversion circuit connected to convert the voltage of the secondary battery into a current, a current-to-voltage conversion circuit for converting the current of the voltage-to-current conversion circuit into a voltage, and a voltage proportional to the voltage of the secondary battery based on the voltage of the current-to-voltage conversion circuit. a first current generating circuit for generating a first current; a second current generating circuit for generating a second current proportional to a voltage for using an output terminal of the resistor circuit as a voltage for fault diagnosis; A current mirror circuit for passing a fault detection current according to

Moreover, the fault diagnosis method of the secondary battery monitoring apparatus of this invention is a 1st resistance circuit which is connected at both ends of a 1st secondary battery, and outputs a 1st detection voltage from an output terminal, and a 1st secondary based on a 1st detection voltage. A first detection circuit for detecting an abnormality in the battery, a first voltage-to-current conversion circuit connected to both ends of the first secondary battery and converting the voltage of the first secondary battery into a current, and a second battery connected in series with the first secondary battery A second resistance circuit connected to both ends of the secondary battery and outputting a second detection voltage from an output terminal, a second detection circuit configured to detect abnormality of the second secondary battery based on the second detection voltage, and a second secondary battery a second voltage-to-current conversion circuit connected to both ends of the second battery to convert the voltage of the second secondary battery into a current, and an input terminal having a first voltage-current conversion circuit through a first switch and a second voltage-current through a second switch a current-to-voltage conversion circuit connected to the conversion circuit and converting the current of the first or second voltage-current conversion circuit to a voltage; and a first current proportional to the voltage of the secondary battery based on the voltage of the current-to-voltage conversion circuit a first current generating circuit; a second current generating circuit generating a second current proportional to a voltage for using the output terminal of the first or second resistor circuit as a voltage for fault diagnosis; A secondary battery comprising a current mirror circuit for passing a failure detection current, a third switch for passing a failure detection current to an output terminal of the first resistor circuit, and a fourth switch for passing a failure detection current to an output terminal of the second resistor circuit A method for diagnosing a failure of a secondary battery monitoring device for detecting an abnormality, wherein a voltage is applied from an external power source to a terminal connected to both ends of a second secondary battery, and the first switch is turned off, the second switch is turned on, and the third switch is turned on. , the fourth switch is turned off to diagnose a failure of the secondary battery monitoring device according to the detection result of the first detection circuit.

According to the secondary battery monitoring apparatus and the failure diagnosis method of the present invention, it is possible to detect a failure regardless of a failure point or failure mode.

1 is a block diagram showing a secondary battery monitoring device of the present invention.
2 is a block diagram showing a failure diagnosis method of the secondary battery monitoring apparatus of the present invention.

1 is a block diagram showing a secondary battery monitoring apparatus 100 according to an embodiment of the present invention.

The secondary battery monitoring device 100 includes voltage-current conversion circuits 11 and 21 , selection switches 12 and 22 , resistance circuits 13 and 23 , reference voltage circuits 14 and 24 , and a switch ( 15, 16, 25, 26, comparators 17, 18, 27, 28, current-to-voltage conversion circuit 31, operational amplifiers 32, 35, MOS transistors 33, 36, and resistors (34, 37), a reference voltage circuit 38, and a current mirror circuit 39 are provided.

Moreover, although not shown in figure, the secondary battery monitoring apparatus 100 is equipped with the control circuit etc. which control the charge/discharge control switch according to voltage information of the secondary batteries C1, C2, etc.

The comparators 17 and 27 are comparators for detecting overdischarge, and the comparators 18 and 28 are comparators for detecting overcharge. In the resistor circuit 13, three resistors 13a, 13b, and 13c are connected in series, and the resistance values thereof are Ra, Rb, and Rc. In the resistor circuit 23, three resistors 23a, 23b, and 23c are connected in series, and the resistance values thereof are Ra, Rb, and Rc. The reference voltage circuits 14 and 24 output the reference voltage vref.

The voltage-current conversion circuits 11 and 21 , the current-to-voltage conversion circuit 31 , the operational amplifier 32 , the MOS transistor 33 , and the resistor 34 are in the resistor circuit 13 ( 23 ). It is a current generation circuit that generates a current Ic for making the node detected by the comparators 17, 18 (27, 28) of the reference voltage circuit 14 (24) equal to the reference potential of the reference voltage circuit 14 (24). The operational amplifier 35, the MOS transistor 36, the resistor 37, and the reference voltage circuit 38 are comparators 17, 18 (27, 28) in the resistor circuit 13 (23)) It is a current generation circuit that generates a current Ir for setting the node detected by the to a voltage for fault diagnosis.

In the voltage-current conversion circuit 11 , an input terminal is connected to both ends of the secondary battery C1 , and an output terminal is connected to an input terminal of the current-to-voltage conversion circuit 31 via a selection switch 12 . The resistance circuit 13 has both ends connected to both ends of the secondary battery C1 , a first output terminal connected to an inverting input terminal of the comparator 17 , and a second output terminal connected to a non-inverting input of the comparator 18 . connected to the terminal. The reference voltage circuit 14 has an output terminal connected to a non-inverting input terminal of the comparator 17 and an inverting input terminal of the comparator 18 .

In the voltage-current conversion circuit 21 , an input terminal is connected to both ends of the secondary battery C2 , and an output terminal is connected to an input terminal of the current-to-voltage conversion circuit 31 via a selection switch 22 . The resistance circuit 23 has both ends connected to both ends of the secondary battery C2 , a first output terminal connected to an inverting input terminal of the comparator 27 , and a second output terminal connected to a non-inverting input of the comparator 28 . connected to the terminal. The reference voltage circuit 24 has an output terminal connected to a non-inverting input terminal of the comparator 27 and an inverting input terminal of the comparator 28 . The comparators 17 , 18 , 27 , 28 are connected to input terminals of a control circuit whose output terminals are not shown.

The operational amplifier 32 has a non-inverting input terminal connected to an output terminal of the current-to-voltage conversion circuit 31 , and an output terminal connected to a gate of the MOS transistor 33 . The MOS transistor 33 has a source connected to one end of a resistor 34 and an inverting input terminal of the operational amplifier 32 .

The operational amplifier 35 has a non-inverting input terminal connected to the output terminal of the reference voltage circuit 38 , and the output terminal is connected to the gate of the MOS transistor 36 . The MOS transistor 36 has a source connected to one end of a resistor 37 and an inverting input terminal of the operational amplifier 35 .

The current mirror circuit 39 has an input terminal connected to the drain of the MOS transistor 36 and an output terminal connected to the drain of the MOS transistor 33 . The switch 15 is connected between the output terminal of the current mirror circuit 39 and the inverting input terminal of the comparator 17 . The switch 16 is connected between the output terminal of the current mirror circuit 39 and the non-inverting input terminal of the comparator 18 . The switch 25 is connected between the output terminal of the current mirror circuit 39 and the inverting input terminal of the comparator 27 . The switch 26 is connected between the output terminal of the current mirror circuit 39 and the non-inverting input terminal of the comparator 28 .

The voltage-to-current conversion circuit 11 ( 21 ) converts the voltage of the secondary battery C1 ( C2 ) into a current and inputs it to the current-to-voltage conversion circuit 31 . The current-to-voltage conversion circuit 31 converts the current of the voltage-to-current conversion circuit 11 ( 21 ) into a voltage and inputs it to the non-inverting input terminal of the operational amplifier 32 . The operational amplifier 32 controls the gate of the MOS transistor 33 so that the voltage generated in the resistor 34 becomes equal to the voltage of the current-to-voltage conversion circuit 31 . At that time, the current flowing through the resistor 34 is a current proportional to the voltage of the secondary battery, and its value is Ic. The operational amplifier 35 controls the gate of the MOS transistor 36 so that the voltage generated in the resistor 37 becomes equal to the voltage of the reference voltage circuit 38 . In that case, let the value of the current flowing through the resistor 37 be Ir.

Next, the malfunction diagnosis function of the secondary battery monitoring apparatus 100 is demonstrated.

When diagnosing a fault in the circuit for monitoring the secondary battery C1, the selection switch 12 is turned on and the selection switch 22 is turned off. The voltage-to-current conversion circuit 11 converts the voltage VC1 of the secondary battery C1 into a current, and inputs it to the current-to-voltage conversion circuit 31 via the selection switch 12 . The current-to-voltage conversion circuit 31 converts the input current into a voltage VC1 , and a current Ic proportional to the voltage VC1 of the secondary battery C1 by the operational amplifier 32 , the resistor 34 , and the MOS transistor 33 . get

Here, the resistance value R34 of the resistor 34 is switched to be equal to the upper resistance value of the resistance circuit of the comparator to be diagnosed, that is, when the comparator 17 is diagnosed, the resistance value Ra, the comparator 18 is diagnosed In this case, the resistance value Ra + Rb.

In addition, the voltage of the reference voltage circuit 38 is also switched according to the comparator to be diagnosed. The voltage value of the reference voltage circuit 38 outputs a voltage Vud less than the reference voltage vref when diagnosing the comparator 17 , and outputs a voltage Vod higher than the reference voltage vref when diagnosing the comparator 18 . .

In addition, the resistance value R37 of the resistor 37 is switched to the equivalent input resistance value of the resistance circuit seen from the input part of the comparator to be diagnosed. Therefore, the resistance value R37 is 1/{1/Ra + 1/(Rb + Rc)} when diagnosing the comparator 17 and 1/{1/(Ra + Rb) when diagnosing the comparator 18 . ) + 1/Rc}.

These switching are performed by a control signal of a test circuit (not shown).

Then, a current corresponding to the current Ic flowing through the resistor 34 and the current Ir flowing through the resistor 37 flows into the resistor circuit 13 or flows out from the resistor circuit 13, so that the resistor circuit 13 and the reference voltage circuit (14) is diagnosed.

Next, the operation of the failure diagnosis will be described.

By turning on the selection switch 12, the resistance value R34 becomes the resistance value Ra, the resistance value R37 becomes 1/{1/Ra + 1/(Rb + Rc)}, and the voltage of the reference voltage circuit 38 becomes the voltage Vud. set By setting in this way, the current Ic is set to VC1/Ra, and the current Ir is set to Vud·{1/Ra+1/(Rb+Rc)}.

When the switch 15 is turned on, a fault detection current Ic - Ir flows through the switch 15 from the connection point of the resistor 13a and the resistor 13b to the resistor 34, and the inverted input of the comparator 17 is The voltage at the terminal becomes the voltage Vud. At this time, the current Ic makes the potential of the connection point of the resistor 13a and the resistor 13b equal to the potential of the negative electrode of the secondary battery C1, and the current Ir is the voltage of the connection point of the resistor 13a and the resistor 13b. The potential is raised from the potential of the negative electrode of the secondary battery C1 by the voltage Vud. That is, the voltage Vud can be applied to the inverting input terminal of the comparator 17 irrespective of the voltage VC1 of the secondary battery C1 .

Here, since the voltage Vud is lower than the reference voltage vref, the comparator 17 detects overdischarge. Accordingly, an abnormality in which the reference voltage vref becomes low can be detected because the comparator 17 does not detect overdischarge. Moreover, an abnormality in which the resistance value Ra becomes low can also be detected because the comparator 17 does not detect an overdischarge. Moreover, even when the resistance value Rb or the resistance value Rc becomes high, detection becomes possible because the comparator 17 does not detect an overdischarge.

Next, the switch 15 is turned off, the resistance value R34 is changed to the resistance value Ra + Rb, the resistance value R37 is 1/{1/(Ra + Rb) + 1/Rc}, and the voltage of the reference voltage circuit 38 is is set to the voltage Vod. By setting in this way, the current Ic is set to VC1/Ra+Rb, and the current Ir is set to Vod·{1/(Ra+Rb)+1/Rc}.

When the switch 16 is turned on, a current Ir - Ic for fault detection flows from the current mirror circuit 39 through the switch 16 to the connection point between the resistor 13b and the resistor 13c, and the comparator 18 . The voltage at the non-inverting input terminal of is the voltage Vod . At this time, the current Ic makes the potential of the connection point of the resistor 13b and the resistor 13c equal to the potential of the negative electrode of the secondary battery C1, and the current Ir is the voltage of the connection point of the resistor 13b and the resistor 13c. The potential is raised from the potential of the negative electrode of the secondary battery C1 by the voltage Vod. That is, the voltage Vod can be applied to the non-inverting input terminal of the comparator 18 irrespective of the voltage VC1 of the secondary battery C1 .

Here, since the voltage Vod is higher than the reference voltage vref, the comparator 18 detects overcharge. Therefore, an abnormality in which the reference voltage vref becomes high can be detected because the comparator 18 does not detect overcharge. Also, an abnormality in which the resistance value Rc becomes low can be detected because the comparator 18 does not detect overcharge. Moreover, an abnormality in which the resistance value Ra or the resistance value Rb becomes high can also be detected because the comparator 18 does not detect overcharge.

Moreover, as long as the resistance value Rb becomes low, when the voltage VC1 of the secondary battery C1 is normal, either of the comparators 17 and 18 malfunctions, and a failure detection becomes possible.

In the case of diagnosing the failure of the circuit for monitoring the secondary battery C2, it is possible to diagnose those circuits in the same manner as described above.

In addition, by using the voltage-current conversion circuit 11 operating at the time of diagnosis, only the voltage-current conversion circuit 11 is operated when the switches 15 and 16 are turned off, so that the secondary battery C1 and the secondary battery C2 are It is also possible to detect a connection failure of a connection point of

Fig. 2 is a block diagram showing a method for diagnosing a fault in the fault diagnosis circuit added in the present embodiment. Hereinafter, a method for performing fault diagnosis of the current generation circuit will be described.

The difference from FIG. 1 is that when the switch 15 or 16 is turned on, the selection switch 12 is turned off and the selection switch 22 is turned on. And an external power supply capable of changing a voltage is connected to the terminal to which the secondary battery C2 is to be connected.

In such a state, the resistance circuit 13 applies the voltage of the secondary battery C1 and generates a current Ic and a current Ir based on the current of the voltage-to-current conversion circuit 21 . A current for fault detection determined by Specifically, as for the current for fault detection, when the switch 15 is turned on, the current Ic - Ir flows out from the resistance circuit 13 , and when the switch 16 is turned on, the current Ir - Ic flows through the resistance circuit 13 . ) is introduced into

In this state, if the voltage of the external power supply is set lower than the voltage of the secondary battery C1, the current Ic becomes smaller than the current generated from the voltage of the secondary battery C1, so the voltage of the inverting input terminal of the comparator 17 is higher than the voltage Vud. Here, if this voltage is made higher than the reference voltage vref, the comparator 17 does not detect overdischarge, so that there is no failure in the current generation circuit for generating the currents Ic and Ir including the voltage-to-current conversion circuit 21 . that can be detected Moreover, a failure in which the voltage of the inverting input terminal of the comparator 17 of the resistor circuit 13 becomes too low can be detected.

Similarly, the switch 15 is turned off and the switch 16 is turned on to change the voltage of the external power supply so that the failure of the overcharge detection circuit and the voltage of the non-inverting input terminal of the comparator 18 of the resistor circuit 13 are reduced. It is possible to detect excessively high faults.

Further, by turning on the selection switch 12 and turning off the selection switch 22 to connect an external power supply capable of changing a voltage to the terminal to which the secondary battery C1 is to be connected, and diagnose a failure, the voltage-current conversion circuit It can be detected that there is no fault in the current generating circuit including (11).

As described above, the secondary battery monitoring device 100 of the present embodiment includes a current generating circuit that generates a current Ic and a current Ir, a current mirror circuit 39, and switches 15, 16 (25, 26). )) to allow a desired current to flow through the resistor circuit, it becomes possible to detect a failure in the circuit monitoring the secondary battery C1 (C2) regardless of the failure point or failure mode.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of this invention, various changes are possible.

For example, although the example provided with the circuit which detects an overdischarge and the circuit which detects overcharge was provided as a circuit which monitors a secondary battery, the structure provided with either one may be sufficient. In addition, although a circuit for monitoring two secondary batteries connected in series is exemplified, the number of secondary batteries may be one, and three or more secondary batteries may be implemented in the same manner. In addition, although it has been described that the current generation circuit is constituted by an operational amplifier, a MOS transistor, and a resistor, it is not limited to this circuit as long as the function is satisfied. Moreover, although the resistance value of each resistance of the resistance circuit 13 and the resistance circuit 23 was made into the same value, the resistance value of each resistance may differ, for example, when the voltage of the secondary batteries C1 and C2 differs. In that case, it is necessary to separately provide a current generation circuit.

100: secondary battery monitoring device
11, 21: voltage-current conversion circuit
14, 24, 38: reference voltage circuit
17, 18, 27, 28: comparator
31: current voltage conversion circuit
32, 35: op amp
39: current mirror circuit

Claims (5)

A secondary battery monitoring device for detecting abnormalities in secondary batteries, comprising:
a resistance circuit connected to both ends of the secondary battery and outputting a detection voltage from an output terminal;
a detection circuit for detecting an abnormality of the secondary battery based on the detection voltage;
a voltage-current conversion circuit connected to both ends of the secondary battery and converting the voltage of the secondary battery into a current;
a current-to-voltage conversion circuit for converting the current of the voltage-to-current conversion circuit into a voltage;
a first current generation circuit for generating a first current proportional to the voltage of the secondary battery based on the voltage of the current-to-voltage conversion circuit;
a second current generating circuit for generating a second current proportional to a voltage for using the output terminal of the resistor circuit as a voltage for fault diagnosis;
a current mirror circuit for passing a fault detection current according to the first current and the second current;
and a switch for passing the fault detection current to the output terminal of the resistor circuit. A secondary battery monitoring device for detecting abnormalities in secondary batteries, comprising:
a resistance circuit connected to both ends of the secondary battery and outputting an overdischarge detection voltage from a first output terminal and outputting an overcharge detection voltage from a second output terminal;
an overdischarge detection circuit configured to detect overdischarge of the secondary battery based on the overdischarge detection voltage;
an overcharge detection circuit configured to detect overcharge of the secondary battery based on the overcharge detection voltage;
a voltage-current conversion circuit connected to both ends of the secondary battery and converting the voltage of the secondary battery into a current;
a current-to-voltage conversion circuit for converting the current of the voltage-to-current conversion circuit into a voltage;
a first current generation circuit for generating a first current proportional to the voltage of the secondary battery based on the voltage of the current-to-voltage conversion circuit;
a second current generating circuit for generating a second current proportional to a voltage for using the first output terminal and the second output terminal of the resistor circuit as a voltage for fault diagnosis;
a current mirror circuit for passing a fault detection current according to the first current and the second current;
a first switch for passing the fault detection current to a first output terminal of the resistor circuit;
and a second switch for passing the fault detection current to a second output terminal of the resistor circuit. 3. The method of claim 2,
When the first switch is turned on and the second switch is turned off, diagnosing a failure of the over-discharge detection circuit,
and diagnosing a failure of the overcharge detection circuit when the first switch is turned off and the second switch is turned on. 4. The method of claim 3,
When diagnosing a failure of the over-discharge detection circuit and when diagnosing a failure of the over-charge detection circuit,
The first current generating circuit converts and outputs the first current,
and the second current generating circuit switches and outputs the second current. a first resistor circuit connected to both ends of the first secondary battery and outputting a first detection voltage from an output terminal;
a first detection circuit for detecting an abnormality of the first secondary battery based on the first detection voltage;
a first voltage-current conversion circuit connected to both ends of the first secondary battery and converting the voltage of the first secondary battery into a current;
a second resistor circuit connected to both ends of a second secondary battery connected in series with the first secondary battery and outputting a second detection voltage from an output terminal;
a second detection circuit for detecting an abnormality of the second secondary battery based on the second detection voltage;
a second voltage-current conversion circuit connected to both ends of the second secondary battery and converting the voltage of the second secondary battery into a current;
An input terminal is connected to the first voltage-to-current conversion circuit via a first switch and to the second voltage-to-current conversion circuit via a second switch, and converts the current of the first or second voltage-to-current conversion circuit into a voltage a current-to-voltage conversion circuit that converts
a first current generation circuit for generating a first current proportional to the voltage of the secondary battery based on the voltage of the current-to-voltage conversion circuit;
a second current generating circuit for generating a second current proportional to a voltage for using the output terminal of the first or second resistor circuit as a voltage for fault diagnosis;
a current mirror circuit for passing a fault detection current according to the first current and the second current;
a third switch for passing the fault detection current to the output terminal of the first resistor circuit;
A failure diagnosis method of a secondary battery monitoring device for detecting abnormality in a secondary battery including a fourth switch for passing the failure detection current to the output terminal of the second resistor circuit,
applying a voltage from an external power source to a terminal to which both ends of the second secondary battery are connected,
by turning off the first switch, turning on the second switch, turning on the third switch, and turning off the fourth switch,
A failure diagnosis method of a secondary battery monitoring apparatus for diagnosing a failure of the secondary battery monitoring apparatus according to a detection result of the first detection circuit.

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