JP2001333541A - Charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve anti-noise characteristic of a charging device that transfers a charging state, based on the result of the detections of detecting signals. SOLUTION: A state-detecting means 1a of the charging device 1 detects the state of a secondary battery 2. A state-inferring means 1b infers the state of the secondary battery 2 based on the results of a plurality of detections by the state-detecting means 1a. A charging means 1c charges the secondary battery 2 by an appropriate charging current or charging voltage, based on the result of the presumption by the state-presuming means 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device, and more particularly, to a charging device that performs charging while monitoring the state of a secondary battery.

[0002]

2. Description of the Related Art In recent years, secondary batteries that can be repeatedly used by charging are used in many electronic devices.

[0003] There are two methods of charging a secondary battery: a method of charging over a long time with a current of about 1/10 of the battery capacity and a method of charging over a short time with a current of about the same as the battery capacity. There is a street.

[0004] The latter method is also called rapid charging, and since charging is completed in a short time, it is rapidly spreading in recent years.

[0005]

In the case of fast charging,
It is necessary to select an optimal charging voltage and charging current according to the state of the secondary battery. In the conventional charging device, the state of the secondary battery is appropriately detected, and an optimum charging voltage or charging current is selected according to the detected state.

Power for charging a secondary battery is often supplied from a commercial power supply, and such a commercial power supply may be mixed with noise generated by other electronic devices. Many.

[0007] When noise is mixed in the power supply voltage, the influence is exerted on the battery voltage and the charging current, and the internal circuit erroneously detects the state of the secondary battery. As a result, the charging is completed even though the charging is not completed. There is a problem that the processing ends.

The present invention has been made in view of an abnormal situation, and provides a charging device that operates normally even when noise is mixed in the power supply voltage.

[0009]

According to the present invention, in order to solve the above-mentioned problems, in a charging device for charging while monitoring the state of a secondary battery, state detecting means for detecting the state of the secondary battery, State estimating means for estimating the state of the secondary battery based on a plurality of detection results by the state detecting means; and charging means for charging with an appropriate charging current or charging voltage based on the estimation result by the state estimating means. ,
Is provided.

Here, the state detecting means detects the state of the secondary battery. The state estimating unit estimates the state of the secondary battery based on a plurality of detection results by the state detecting unit. The charging means charges with an appropriate charging current or charging voltage based on the estimation result by the state estimating means.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a principle diagram for explaining the operation principle of the present invention. As shown in this figure, the charging device 1 according to the present invention includes a state detecting unit 1a, a state estimating unit 1b,
And charging means 1c.

The state detecting means 1a detects the state of the secondary battery such as voltage, current and temperature. State estimation means 1
b estimates the state of the secondary battery 2 based on the detection results of a plurality of times by the state detecting means 1a.

The charging means 1c performs charging while controlling the charging current or the charging voltage based on the result of estimation by the state estimating means 1b. Next, the operation of the above principle diagram will be described.

Now, it is assumed that the secondary battery 2 is connected to the charging device 1 and charging is started. Then, the state detecting means 1a detects the state of the secondary battery 2 and the state estimating means 1
Notify b.

The state estimating means 1b estimates the state of the secondary battery based on the detection result of the state detecting means 1a. At that time, only when a certain estimation result is continuously obtained, the estimation result is regarded as a correct result. For example, when charging is started, it is estimated from the voltage of the secondary battery 2 whether or not the battery to be charged is normal. Even if it is estimated that the first process is abnormal, the process is repeated again. For example,
It is determined that an abnormality is present only when it is estimated that the abnormality has occurred five times in a row.

The charging means 1c performs a charging process on the rechargeable battery 2 based on the estimation result of the state estimating means 1b with an optimal charging voltage or charging current at that time.
According to the above processing, only when the state estimation means 1b continuously obtains the same estimation result, the notification is made to the charging means 1c.
Even when the charging voltage or the charging current temporarily indicates an abnormality, it is possible to prevent the state of the secondary battery 2 from being erroneously estimated.

Next, an embodiment of the present invention will be described. FIG. 2 is a diagram illustrating a configuration example of the embodiment of the present invention. As shown in this figure, the charging device according to the present invention includes a power supply 10, an output drive unit 11, a control switching unit 12, operational amplifiers 13, 14, resistors 15, 16, a charging voltage detection circuit 17, a charging current detection circuit 18, Control logic circuit 1
9 and a current detection resistor 20.

The power supply 10 includes a switching regulator, a transformer, and the like. The power supply 10 steps down and rectifies the commercial power to generate a predetermined DC voltage, and supplies the DC voltage to the output drive unit 11.

The output drive unit 11 is controlled by the operational amplifier 13 or 14 and charges a lithium battery 21 as a secondary battery with a predetermined voltage or current.

The operational amplifier 13 forms a constant voltage control circuit, and operates in accordance with the difference between the terminal voltage V of the lithium battery 21 detected by the charging voltage detection circuit 17 and the reference voltage signal Vref supplied from the control logic circuit 19. The output drive unit 11 is controlled to charge the lithium battery 21 at a constant voltage.

The operational amplifier 14 forms a constant current control circuit, and a voltage generated across the current detection resistor 20 detected by the charging current detection circuit 18 and the control logic circuit 1
The output drive unit 11 is controlled in accordance with the difference from the reference voltage signal Iref supplied from the control unit 9 to charge the lithium battery 21 at a constant current.

The resistors 15 and 16 are connected to a control logic circuit 19
Are supplied to the inverting input terminals of the operational amplifiers 13 and 14.

The charging voltage detecting circuit 17 is provided for the lithium battery 2
1 is detected at the output terminal and the operational amplifier 13
And to the control logic circuit 19. The charging current detection circuit 18 detects a voltage generated across the current detection resistor 20 and supplies the voltage to the control logic circuit 19 and the operational amplifier 14.

The control logic circuit 19 includes a reference voltage signal Vre corresponding to the charging voltage or the charging current detected by the charging voltage detecting circuit 17 and the charging current detecting circuit 18.
f and Iref are generated to control the operational amplifiers 13 and 14, respectively, and the control switching unit 12 is controlled to select either constant current charging or constant voltage charging. Furthermore,
When the temperature of the lithium battery 21 is abnormal, control for terminating charging is performed based on a temperature signal from a thermistor 21b built in the lithium battery 21.

The current detecting resistor 20 is constituted by a resistance element having a small value, generates a voltage corresponding to a current (charging current) flowing from the negative terminal of the lithium battery 21 to the ground, and supplies the voltage to the charging current detecting circuit 18. I do.

The lithium battery 21 includes the lithium battery body 2
1a and the thermistor 21b. The lithium battery main body 21a is, for example, a one-cell coke-based lithium ion battery.

The resistance of the thermistor 21b changes according to the internal temperature of the lithium battery 21. Subsequently, the operation of the embodiment shown in FIG. 2 will be described. Hereinafter, first, the conventional operation will be described with reference to FIGS. 3 to 6, and then the operation in the case of the present invention will be described with reference to FIGS. 7 to 11.

FIG. 3 is a flowchart showing an example of a conventional operation at the time of charging. This flowchart is
This is executed when the lithium battery 21 is connected to the charging device and the power supply 10 is connected to the commercial power supply. [S1] The control logic circuit 19 includes the charging voltage detection circuit 1
It is determined whether or not the battery voltage detected by step 7 is abnormal. If abnormal, the process proceeds to step S2, and otherwise, the process proceeds to step S3. [S2] The control logic circuit 19 stops charging and ends the processing. [S3] The control logic circuit 19 determines whether or not the battery temperature is abnormal with reference to the resistance value of the thermistor 21b. If the battery temperature is abnormal, the process proceeds to step S2; otherwise, the process proceeds to step S4. Proceed to. [S4] The control logic circuit 19 determines that the battery voltage is 3.2 V
It is determined whether the voltage is equal to or more than 3.2 V. If the voltage is equal to or more than 3.2 V, the process proceeds to step S8.
Go to 5. [S5] The control logic circuit 19 charges the lithium battery 21 by constant current control. Specifically, the control logic circuit 19 first controls the control switching unit 12 to switch the connection to the operational amplifier 14 side, and supplies the lithium current to the lithium battery 21 with reference to the charging current detected by the charging current detection circuit 18. For example, a reference voltage signal Iref is generated so that the current to be supplied becomes constant at 0.2 A and supplied to the operational amplifier 14. [S6] The control logic circuit 19 executes abnormality detection processing for detecting that the voltage, current, and temperature of the lithium battery 21 are abnormal. This processing will be described in detail with reference to FIG. [S7] The control logic circuit 19 determines that the battery voltage is 3.2V.
It is determined whether the voltage is less than 3.2 V. If the voltage is less than 3.2 V, the process returns to step S5.
Proceed to 8. [S8] The control logic circuit 19 charges the lithium battery 21 by constant current control. More specifically, the control logic circuit 19 refers to a reference voltage signal such that the current supplied to the lithium battery 21 with reference to the charging current detected by the charging current detection circuit 18 becomes constant at 1.0 A, for example. Iref is generated and supplied to the operational amplifier 14. [S9] The control logic circuit 19 performs an abnormality detection process. Details of this processing will be described later with reference to FIG. [S10] The control logic circuit 19 determines that the battery voltage is 4.2.
If it is less than V, the process returns to step S8 and repeats the same processing. Otherwise, the process proceeds to step S11. [S11] The control logic circuit 19 charges the lithium battery 21 by constant voltage control. Specifically, the control logic circuit 19 first controls the control switching unit 12 to switch to the operational amplifier 13 side, and is applied to the lithium battery 21 with reference to the charging voltage detected by the charging voltage detection circuit 17. A reference voltage signal Vref is generated so that the voltage becomes constant at 4.2 V, for example, and supplied to the operational amplifier 13. [S12] The control logic circuit 19 executes an abnormality detection process. Details of this processing will be described later with reference to FIG. [S13] The control logic circuit 19 determines that the charging current is 0.1
It is determined whether it is A or more. If it is 0.1 A or more, the process returns to step S11 to repeat the same processing. Otherwise, the processing ends.

Next, referring to FIG. 4, step S in FIG.
The details of the abnormality detection processing shown in 6, S9, and S12 will be described. When this flowchart is started, the following processing is executed. [S30] The control logic circuit 19 determines whether or not the battery voltage is abnormal with reference to the output of the charging voltage detection circuit 17,
If it is determined that there is an abnormality, the process proceeds to step S33; otherwise, the process proceeds to step S31. [S31] The control logic circuit 19 refers to the output of the charging current detection circuit 18 to determine whether the charging current is abnormal,
If it is determined to be abnormal, the process proceeds to step S33; otherwise, the process proceeds to step S32. [S32] The control logic circuit 19 includes the thermistor 21b
It is determined whether or not the battery temperature is abnormal with reference to the output of step S33. If it is determined that the battery temperature is abnormal, the process proceeds to step S33, and otherwise returns to the original process. [S33] The control logic circuit 19 stops charging and ends the process.

Next, with reference to FIG. 5, the change over time of the charging voltage and the charging current according to the method shown in FIG. 3 will be described. The current values shown below were determined based on a lithium battery having a capacity of 1000 mAH.

When charging is started, the battery voltage and the battery temperature are checked by the processing of steps S1 and S3 shown in FIG. 3. If there is no abnormality, the battery voltage is 3.2 V or more in step S4. Is determined. In this example, since the voltage is less than 3.2 V, the process proceeds to step S5, and charging with a constant current (0.2 A) is started.

As a result, the voltage of the battery gradually increases (see p1). When the voltage of the battery becomes 3.2 V or more, the constant current control in step S8 is started,
Charging with a constant current (1.0 A) is started (see P2).

When the battery voltage becomes 4.2 V or more, the constant voltage control shown in step S11 is started, and charging with the constant voltage (4.2 V) is started. When the constant current control is started, the charging current gradually decreases (see P3),
If the charging current is less than 0.1 A, the charging is terminated.

Although the charging rate when the charging current is 0.1 A is 95%, it is not shown in FIG.
Thereafter, in order to bring the charging rate close to 100%, it is possible to continue constant voltage charging of about 1 A called trickle charging.

Next, the operation when noise is mixed will be described with reference to FIG. Assuming that the voltage noise nv1 is mixed during the charging by the voltage control shown in step S11, the abnormal voltage is detected by the processing of step S30 relating to the abnormality detection processing, and the charging processing ends. In this case, since the processing is interrupted during the charging, the voltage of the lithium battery becomes a voltage V1 which is considerably lower than the voltage at the time of full charge.

As shown in FIG. 6, the current noise ni1
Is mixed, the process ends at step 13 assuming that the charging current is 0.1 A or more. As a result, charging is interrupted, so that the voltage of the lithium battery is a voltage V2 slightly lower than the voltage at the time of full charge.

As described above, in the case of the conventional example, when noise is mixed into the power supply, a malfunction is induced and the charging is interrupted. Next, referring to FIGS.
The operation of the present invention will be described. This processing is the same as the main processing shown in FIGS. 3 and 4, except that steps S50, S52, S53, S56, S59, S62,
The contents of the processes of S100 to S103 are partially changed. Here, the contents described in parentheses for each process are as follows:
This shows the target of the judgment. For example, in the case of “battery voltage determination processing (voltage abnormality)” in step S50, it is determined whether the voltage is abnormal.

FIG. 9 is a diagram showing the details of the "battery voltage determination process (voltage abnormality)" in step S50. When this flowchart is started, the following processing is executed. [S80] The control logic circuit 19 clears the built-in counters # 1 and # 2. [S81] The control logic circuit 19 refers to the detection result of the charging voltage detection circuit 17, and determines whether or not the battery voltage is abnormal. If the battery voltage is abnormal, the process proceeds to step S85,
Otherwise, the process proceeds to step S82. [S82] The control logic circuit 19 clears the counter # 1 and increments the counter # 2 by one. [S83] The control logic circuit 19 determines whether or not the value of the counter # 2 is equal to or greater than a predetermined threshold Th. If the value is equal to or greater than Th, the next step on the NO side (step S5)
Go to 2), otherwise go to step S84. [S84] After waiting for a predetermined time, the control logic circuit 19 returns to step S81 and repeats the same processing as described above. [S85] The control logic circuit 19 clears the counter # 2 and increments the counter # 1 by one. [S86] The control logic circuit 19 determines whether or not the value of the counter # 1 is equal to or greater than the threshold value Th. If the value is equal to or greater than the threshold value th, the control logic circuit 19 proceeds to the next step (step S51) on the YES side. Proceeds to step S87. [S87] After waiting for a predetermined time, the control logic circuit 19 returns to step S81 and repeats the same processing as described above.

According to the above processing, the branch of the processing is performed only when the judgment contents described in parentheses have the same judgment result continuously over the threshold Th. For example, FIG.
In the example of the above, the judgment content that "the battery voltage is abnormal" is
The processing branch occurs only when the same judgment result (for example, the battery voltage is normal) is obtained continuously for the number of times corresponding to h (for example, when the battery voltage is normal). become.

Steps S52, S53, S56,
The processing of S59, S62, and S100 to S103 is the same as the above case except for the content of the determination.

Next, the operation of the embodiment of the present invention will be described with reference to FIG. As shown in this figure, it is assumed that voltage noises nv1 to nv3 and current noises ni1 to ni2 are input during the constant voltage control shown in step S60. At this time, it is assumed that Th = 2.

If the charge voltage determination process shown in step S100 executes the voltage determination process at the same timing T1 when the first noise nv1 is input, it is determined that the voltage is abnormal. However, step S1
In the process of 00, since the abnormality is not determined unless the abnormality of the voltage is continuously detected 2 (= Th) times or more, the voltage is detected again at the timing T2. At timing T2, since there is no noise input, the counter # 1 is cleared, and the counter # 2 is incremented by 1 to "1". At the subsequent timing T3, since there is no noise input, the counter # 1 is incremented by 1 to "2". As a result, the determination is YES, and the process branches to the NO side process.

The same processing is performed on the current noises ni1 and ni2. In this example, the input timing of the first current noise ni1 and the control logic circuit 19
Since the sampling timing T4 of the current data is matched, it is determined that the current is abnormal by the process of step S102. However, at the next sampling timing T5, there is no input of current noise, so that the determination that the current is abnormal is not made continuously. At the next sampling timing T6, no current noise is detected, and as a result, the determination that the current is normal is made twice consecutively. As a result, the process proceeds to step S103 on the NO side. It will branch.

As described above, according to the embodiment of the present invention, the branch of the process is performed only when the same judgment is continuously made a predetermined number of times. A malfunction can be prevented from occurring due to noise or the like.

In the above-described embodiment, the counting process by the counter is performed for both the judgment result for maintaining the state and the judgment result for shifting the state. Only the count process may be performed.

FIG. 11 shows an example of the processing in the case where the count processing is performed only when the state is shifted. When this flowchart is started, the following processing is executed. [S120] The control logic circuit 19 clears the built-in counter # 1. [S121] The control logic circuit 19 refers to the detection result of the charging voltage detection circuit 17, and determines whether or not the battery voltage is abnormal. If the battery voltage is abnormal, the process proceeds to step S122; Branches to the processing on the NO side. [S122] The control logic circuit 19 increments the counter # 1 by one. [S123] The control logic circuit 19 determines whether or not the value of the counter # 1 is equal to or greater than a predetermined threshold Th. If the value is equal to or greater than Th, the process proceeds to the next process on the YES side. Proceeds to step S124. [S124] After waiting for a predetermined time, the control logic circuit 19 returns to step S121 and repeats the same processing as described above.

According to the above-described processing, the counter # 1 is counted up only when the battery voltage is abnormal (when the state is shifted), and when the voltage abnormality is continuously detected at the threshold Th or more. , The charging is stopped (the state is shifted), so that the processing is simpler than the case of FIG.
A similar function can be realized.

Finally, in the above embodiment, the case of voltage noise and current noise has been described as an example. However, as shown in FIG. Similar processing can be performed on the detection signal and other detection signals.

Further, in the present invention, the branch is performed based on the determination result only when the same determination result is obtained continuously. For example, an average value of a plurality of determinations is obtained. It is also possible to perform the processing based on the average value.

[0050]

As described above, according to the present invention, in a charging device for charging while monitoring the state of a secondary battery,
State detecting means for detecting the state of the secondary battery, state estimating means for estimating the state of the secondary battery based on a plurality of detection results by the state detecting means, Since a charging means for charging with a charging current or a charging voltage is provided, it is possible to reliably charge the secondary battery even when noise is mixed in the power supply.

[Brief description of the drawings]

FIG. 1 is a principle diagram for explaining the operation principle of the present invention.

FIG. 2 is a diagram illustrating a configuration example of an embodiment of the present invention.

FIG. 3 is a flowchart illustrating an example of a conventional charging process.

FIG. 4 is a flowchart illustrating details of an abnormality detection process shown in FIG. 3;

FIG. 5 is a timing chart showing temporal changes in charging voltage and charging current when the flowchart shown in FIG. 3 is executed.

FIG. 6 is a timing chart showing a temporal change of a charging voltage and a charging current when noise is mixed in a power supply during execution of the processing of FIG. 3;

FIG. 7 is a flowchart illustrating an example of a charging process according to the present embodiment.

FIG. 8 is a flowchart illustrating details of an abnormality detection process shown in FIG. 7;

FIG. 9 is a diagram illustrating an example of a detailed process of step S50 illustrated in FIG. 7;

FIG. 10 is a timing chart showing a temporal change of a charging voltage and a charging current when noise is mixed into a power supply during execution of the processing of FIG. 7;

FIG. 11 is a diagram showing another example of the detailed process of step S50 shown in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charging device 1a State detecting means 1b State estimating means 1c Charging means 2 Secondary battery 10 Power supply 11 Output drive unit 12 Control switching unit 13, 14 Operational amplifier 15, 16 Resistance 17 Charge voltage detection circuit 18 Charge current detection circuit 19 Control logic circuit 20 Current detection resistor

Claims (3)

[Claims] 1. A charging device that performs charging while monitoring the state of a secondary battery, comprising: state detecting means for detecting a state of the secondary battery; A charging apparatus, comprising: state estimating means for estimating a state of a next battery; and charging means for charging with an appropriate charging current or charging voltage based on an estimation result by the state estimating means. 2. The state estimating means estimates the state of the secondary battery by referring to the detection result by the state detecting means at predetermined time intervals, and the same estimation result is continuously obtained a predetermined number of times or more. 2. The charging device according to claim 1, wherein when obtained, the result is used as an estimation result. 3. A charging method for performing charging while monitoring a state of a secondary battery, comprising: a state detecting step of detecting a state of the secondary battery; A charging method comprising: a state estimating step of estimating a state of a next battery; and a charging step of controlling a charging current or a charging voltage based on an estimation result by the state estimating step.