JP3081392B2 - How to display the battery charge capacity during charging - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for displaying the charged capacity of a battery during charging.

[0002]

2. Description of the Related Art When charging a battery, it is convenient to display the state of charge of the battery. This is because it is possible to estimate the time for full charge by looking at the charge capacity. In addition, when the battery is used while being removed from the charger during charging, the available capacity can be known. When charging a completely discharged battery, the charging capacity can be detected based on the time required to charge the battery. However, the battery to be charged is not always completely discharged. Therefore, it is not possible to calculate the charge capacity of the battery by detecting the charge time. For example, if you are charging a battery that is barely discharged,
When the charging is started, the charge capacity of the battery is almost full.

A method of displaying the charge capacity regardless of the discharge state of the battery has already been developed (Japanese Patent Laid-Open No. 25323/1991).
No. 2). In the method described in this publication, a main charging pause time for pausing the main charging at a constant cycle is provided in order to accurately calculate the charging capacity of the battery. During the main charging suspension time, the charging current is switched to a very small current to detect the battery voltage. The method of detecting the battery voltage during charging cannot calculate the charging capacity accurately. In particular, when a battery is charged at a constant voltage at a constant voltage, it is not possible to detect the voltage during charging and calculate the charge capacity of the battery. that is,
This is because the battery voltage is constant regardless of the charge capacity of the battery. When the main charging is stopped, the battery voltage gradually decreases to a battery voltage at which the charge capacity can be calculated.

[0004]

In this method, the battery voltage is measured by switching to the main charging pause time. After switching to the main charging suspension time, the battery voltage is measured after a certain period of time. This is because immediately after the switching, the polarization is almost the same as the battery voltage during charging, and the charging capacity cannot be accurately calculated from the measured voltage. The closed circuit voltage during charging is affected by the output voltage of the charger and is not related to the charge capacity of the battery. In order to avoid the influence of the battery voltage during charging, the main charging is suspended and the battery voltage is measured. When the main charging is stopped, the battery voltage gradually decreases. In particular, it drops sharply immediately after switching. Thereafter, the voltage drop gradually decreases and approaches a certain voltage value. That is, after switching to the main charging suspension time, the battery voltage fluctuates for a certain period of time. In order to accurately calculate the charging capacity by measuring the voltage of the battery, it is necessary to take a sufficiently long main charging pause time and measure the battery in which the battery voltage does not fluctuate. However, this method requires a significant increase in the main charging pause to measure the battery voltage. The longer the main charging pause time, the longer the battery charging time. In order to shorten the charging time, it is necessary to shorten the main charging suspension time. For this purpose, it is necessary to calculate the charging capacity by measuring the voltage while the voltage of the battery is decreasing during the main charging suspension time. For this reason, the measured potential changes depending on the measurement time. The fluctuation of the measured potential causes an error in calculating the charge capacity. A timer is used to prevent fluctuations in the measured potential during the main charging pause time.
The timer starts counting when switching to the main charging suspension time, and detects the battery voltage after a certain period of time.
That is, the battery voltage is measured after a certain time has elapsed after switching to the main charging suspension time. However, even with this method, the charge capacity of the battery cannot be accurately calculated. This is because the slope at which the voltage drops during the main charging pause changes depending on the charging capacity and charging conditions of the battery. As the battery approaches full charge, the slope at which the battery voltage drops during the main charging pause time decreases. In addition, the larger the charging current of the battery, the larger the gradient of the voltage drop during the main charging suspension time. For this reason,
Even if the battery voltage is measured after a certain period of time after switching to the main charging suspension time, the voltage cannot be measured under the same conditions, which causes an error in calculating the charge capacity.

[0005] The present invention has been developed to solve this drawback. An important object of the present invention is to provide a method for displaying the charge capacity of a battery during charging, in which the charge time can be shortened and the charge capacity of the battery can be accurately displayed.

[0006]

According to the present invention, in order to achieve the above-mentioned object, a battery is charged in the following manner. The method of the present invention provides a main charging pause time at a predetermined cycle during charging,
This is an improved method of detecting the battery voltage during the main charging suspension time and calculating and displaying the charge capacity of the battery from the detected battery voltage.

[0007] The charging capacity display method of the present invention is characterized in that pulse charging or pulse discharging is performed during the main charging suspension time, and thereafter, the voltage of the battery is detected to calculate and display the charging capacity of the battery.

In the method of performing pulse charging during the main charging suspension time, preferably, as shown in FIG. 1, the amount of change in current at the moment when pulse charging is stopped is made equal. In order to realize this, the charging current of the pulse charging is adjusted to be equal to the current value for charging the battery at a constant current. This method has the feature that the charging capacity can be calculated most accurately.

In the method of performing pulse discharge during the main charging pause time, preferably, as shown in FIG. 2, the amount of change in current at the moment when pulse discharge is stopped is made equal. In order to realize this, the current for pulse discharge is adjusted to a constant value. This method also has the advantage that the charge capacity can be accurately calculated.

[0010] In order to measure the battery voltage during the main charging suspension time after stopping the pulse charge or pulse discharge, it is possible to measure the battery voltage after a certain time has elapsed after stopping the pulse charge or pulse discharge. In this case, the current of the battery is set to 0 while the pulse charging and the pulse discharging are stopped.

In the main charging suspension time, the minimum capacity of the battery can be measured to calculate the charging capacity. In this case, after stopping the pulse charging and the pulse discharging, the battery is charged with a small current, and the minimum voltage of the battery is measured. When the battery is charged with a small current during the main charging suspension time, the voltage of the battery gradually decreases and then slowly increases. Therefore, the voltage of the battery becomes the minimum value during the main charging suspension time.

[0012]

The principle of operation of the charging capacity display method of the present invention is shown in FIG.
This will be described with reference to FIG. These voltage and current characteristics indicate characteristics of the lithium ion secondary battery. The main battery is charged with a predetermined current. When the battery is charged at a constant current, pulse charging is not performed. When the battery approaches full charge, the constant current charging is switched to constant voltage charging. When constant voltage charging is performed, as shown in FIG. 1, the charging current of the battery gradually decreases. When the charging current of the battery becomes smaller than the charging current at the time of constant current charging, pulse charging is performed for a certain time (Ta) at the moment when the main charging is stopped. Charge current of pulse charging (IA)
Is adjusted to be equal to the charging current (IA) of the constant current charging. After stopping the pulse charging, a certain time (Tb)
Assuming that the charging current of the battery is 0, the battery voltage is measured. After measuring the battery voltage, switch to main charging. Thereafter, after the main charging for a certain time (Tc), the steps (1) to (4) are repeated, and the battery is fully charged while measuring the charging capacity of the battery.

FIG. 2 shows a charge capacity display method according to the present invention.
As shown in (1), pulse discharge is performed at a constant current at the beginning of the main charging suspension time, and after a predetermined time, the battery voltage is measured to calculate the charge capacity.

As described above, according to the charge capacity display method of the present invention, pulse measurement or pulse discharge is performed before measuring the battery voltage. In the method of performing the pulse charging at the beginning of the main charging suspension time, the change value of the current at the moment when the pulse charging is stopped can be the same regardless of the charging current for main charging the battery. Similarly, in the method of performing the pulse discharge, the change value of the current can be made the same at the moment when the pulse discharge is stopped. Therefore, the charging capacity display method of the present invention can reduce the fluctuation of the voltage drop of the battery after stopping the pulse charging and the pulse discharging, regardless of the charging capacity and the charging current of the battery. Therefore, it is possible to measure the battery voltage under more equal conditions by shortening the main charging suspension time and accurately calculate the charging capacity.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. However, the following examples illustrate a charge capacity display method for embodying the technical idea of the present invention, and the charge capacity display method of the present invention includes measurement conditions, electric circuits used, The format is not specified as follows. The method for displaying the charge capacity of a battery according to the present invention includes
Various changes can be made in the scope of the claims.

Example 1 A non-aqueous secondary battery such as a lithium ion secondary battery is charged in accordance with the current and voltage curves shown in FIGS. 1 and 3 as follows. The main battery is charged by charging the battery with a constant current at a constant current. Every time a predetermined time elapses, the charging current is set to 0 and the main charging is stopped. When charging the battery with constant current, pulse charging is not performed during the main charging pause time. At the end of the main charging suspension time, the battery voltage is detected, and thereafter, the mode is switched to the main charging. The charging capacity is calculated from the voltage of the battery detected during the main charging suspension time and displayed. When the battery approaches full charge, it switches to constant voltage charging. Also in this state, the main charging is stopped at a constant cycle. When charging a battery at a constant voltage, pulse charging is performed immediately after switching to main charging. The charging current for pulse charging is
It is adjusted to be equal to the charging current during constant current charging. After pulse charging for a certain time (Ta), the charging current is set to 0. Assuming that the charging current is 0, the voltage of the battery becomes as shown in FIG.
It gradually decreases. The state in which the battery voltage decreases is that the current is constant immediately before the charging current is set to 0, in other words, the charging condition immediately before the charging current is set to 0 is constant, so that the change in the charging current of the battery causes Does not change. After a certain time (Tb) with the charging current set to 0,
Detect battery voltage. The charge capacity is calculated from the detected battery voltage and displayed. In order to calculate the charging capacity from the measured battery voltage, the calculating means stores a function for calculating the charging capacity of the battery from the measured voltage. The charge capacity with respect to the battery voltage is measured in advance and stored in the arithmetic means. As shown in FIG. 4, the charge capacity of the lithium ion secondary battery increases as the measured voltage of the main charging pause time increases. Preferably, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery has a characteristic that a change in charge capacity with respect to a measured pressure is small even when an ambient temperature changes. Therefore, the charge capacity can be accurately calculated from the measured voltage. After the battery voltage is measured during the main charging pause time, the charging current is increased and constant voltage charging is started. Thereafter, the above steps are repeated to charge the non-aqueous electrolyte secondary battery with a constant current. In the above steps, if the cycle of calculating the battery charge capacity by suspending the main charge is shortened, the changing battery charge capacity can be accurately displayed in real time. However, if this cycle is short, the main charging is frequently stopped, so that the time for fully charging the battery is shortened. Therefore, the cycle in which the main charging is stopped, that is, the time (Tc) for the main charging is usually set to 20 seconds to 10 minutes, preferably 30 seconds to 5 minutes. In addition, if the time for pulse charging the battery is increased, the charging capacity of the battery can be accurately measured. However, if it is too long, there is a problem of overcharging the battery. Therefore, the pulse charging time (Ta) is usually 10 msec to 10 sec, preferably 50 msec.
It is adjusted in the range of c to 5 sec. Further, if the time (Tb) for setting the charging current to 0 after the pulse charging is increased, the charging capacity of the battery can be accurately displayed. However, if this time is long, the time to fully charge the battery becomes long. Therefore,
The time (Tb) during which the battery is not charged is 1 sec to 20 sec.
c, preferably in the range of 1 sec to 15 sec.

In the above embodiment, the charging current of the battery is set to 0 during the main charging suspension time after the pulse charging is stopped. However, according to the present invention, after the pulse charging is stopped, the battery can be charged with a small current and the battery voltage can be measured. In this case, after the pulse charging is stopped, the voltage of the battery is measured during the main charging suspension time as described below. A method of calculating the charge capacity by stopping the pulse charge, charging with a small current, charging the battery with a small current for a certain period of time, or measuring the minimum voltage of the battery when charging with a small current. In this method, charging is performed with a small current after pulse charging during the main charging suspension time. When charging with a small current after pulse charging, the voltage of the battery once drops and then rises when charging with a small current. That is, the voltage becomes the minimum at a certain time. It is also possible to calculate the charging capacity obtained by measuring the minimum voltage. A method in which the charging current of the battery is set to 0 for a certain time after the pulse charging is stopped, and then the battery is charged with a small current. In this method, the battery is charged with pulse charging → charging current 0 → microcurrent during the main charging pause time. When charging with a small current, the minimum voltage of the battery is measured, or the battery is charged with a small current for a certain period of time and the voltage of the battery is measured to calculate the charge capacity. This method is used during the main charging pause time.
The feature is that the time until the battery voltage becomes the minimum voltage can be shortened. After stopping pulse charging, the battery is discharged with a constant current for a certain period of time, and then charged with a small current. In this method, the battery is charged with pulse current → discharge → minute current during the main charging pause time. When charging with a small current, the minimum voltage of the battery is measured, or the battery is charged with a small current for a certain period of time and the voltage of the battery is measured to calculate the charge capacity. This method also has the advantage that the time until the voltage of the battery reaches the minimum voltage can be shortened during the main charging suspension time, similarly to the method.

As described above, FIG. 5 is a block diagram of a circuit for performing pulse charging during the main charging suspension time and thereafter measuring the battery voltage and displaying the charging capacity. The charging circuit shown in this figure charges a non-aqueous secondary battery such as a lithium ion secondary battery. This charging circuit includes a power supply 1 for charging,
A charge control unit 2 controls the output of the power supply 1 to control the state of charge of the battery, and a charge capacity display unit 15.

The power supply 1 includes an input filter 3 for removing noise included in a commercial power supply of AC 100 V, a rectifier circuit 4 for converting input AC to DC, and switching for converting DC of the rectifier circuit 4 to high-frequency AC. Unit 5, a conversion transformer 6 for converting alternating current into a predetermined voltage, and a conversion transformer 6
A rectifying / smoothing circuit 7 for rectifying the AC output of the device and converting it to a smooth DC, a PWM control circuit 8 for controlling the switching unit 5 to control the DC output, and a signal from the charging control means 2.
And a photocoupler 9 that is electrically insulated and inputs to the PWM control circuit 8.

The charge control means 2 includes an output adjustment circuit 10 for adjusting the output of the power supply 1 to control the charge current of the battery, a charge control switch SW2, a calculation means 11, and a voltage detection circuit 12.

The output adjustment circuit 10 includes a constant voltage charging circuit 13
And a constant current charging circuit 14. Constant voltage charging circuit 1
3 and the constant current charging circuit 14 include differential amplifiers 13A and 14A.

The differential amplifier 13A of the constant voltage charging circuit 13
Has a + input terminal connected to the battery via a voltage dividing resistor. The negative input terminal is connected to reference power supplies E1 and E2 via a changeover switch 18. Differential amplifier 13A, 14A
Is connected to the photocoupler 9 via a diode.

This constant voltage charging circuit 13 is a differential amplifier 1
The voltage of the + input terminal of 3A, that is, the divided voltage of the battery is compared with the reference voltage E1 or E2 connected to the-side, and the output of the differential amplifier 13A is inverted to +-. When the voltage of the battery becomes higher than the set voltage, the voltage on the positive side becomes higher than the reference voltage on the negative side. Then, the differential amplifier 1
The output of 3A becomes +, no current flows through the diode, and the light emitting diode of the photocoupler 9 stops emitting light. In this state, the PWM control circuit 8 controls the switching element of the switching unit 5 to lower the output. The reference voltage Es of the constant voltage charging circuit 13 determines a reference voltage for charging the battery at a constant voltage. The battery is charged at a constant voltage by setting the changeover switch to the E1 side of the reference voltage. With the changeover switch set to the E2 side, the battery is pulse-charged. At the time of pulse charging, the battery voltage becomes higher than the voltage at the time of constant voltage charging. Therefore, the reference voltage is set to E1 <E2.

The constant current charging circuit 14 includes a differential amplifier 14A
Is connected to the current detection resistor RS, and the negative input terminal is connected to the reference power supply ES. When the charging current of the battery becomes larger than the set value, the circuit operates as follows.
The voltage of the + side input terminal of 4A becomes higher than the − side reference voltage ES. In this state, the differential amplifier 14A sets the output voltage to + and sets the diode to reverse bias so that the light emitting diode of the photocoupler 9 does not emit light. In this state, the PWM
The control circuit 8 controls the switching element of the switching unit 5 to lower the output, thereby reducing the charging current of the battery. Therefore, the constant current charging circuit 14 performs constant current charging while preventing the charging current of the battery from becoming larger than the set value. The reference voltage ES of the constant current circuit determines the charging current when the battery is main-charged and when the battery is pulse-charged.

The charge control switch SW2 is connected between the power supply 1 and the battery, and is turned off when the charge current of the battery is set to 0, and turned on at other times.

A microcomputer can be used as the calculating means 11.
The calculation means 11 calculates the output of the A / D converter, which is the voltage detection circuit 12, and detects the voltage of the battery during the main charging suspension time. Further, the charge capacity is calculated from the measured voltage. The calculation result is output to the display means 15, and the display means 15 displays the charge capacity of the battery. The display means 15 displays the charge capacity numerically, for example, with the full charge as 100%,
Alternatively, the charging capacity is displayed by changing the number of lights of the plurality of lamps.

Further, the arithmetic means 11 has a built-in timer (not shown), and has a changeover switch SW at a constant cycle.
1 and the charge control switch SW2 are switched. Calculation means 1
1 switches the changeover switch SW1 to the E2 side during pulse charging, and turns off the charge control switch SW2 when the charging current of the battery is set to 0. Therefore, when the main charging is paused and the pulse charging is performed, the arithmetic means 11 keeps the charging control switch SW2 in the ON state, switches the changeover switch SW1 to the E2 side, and then sets the charging current to 0 when Then, the charge control switch SW2 is turned off.

This charging circuit charges a non-aqueous secondary battery such as a lithium ion secondary battery according to the flowchart shown in FIG. This flowchart charges the non-aqueous secondary battery with the voltage and current characteristics shown in FIG. [N1] Start charging. In this state, the battery is charged at a constant current first, and then becomes a constant voltage charge when the battery approaches full charge. [N2] The calculating means 11 switches the changeover switch SW1 to change the reference voltage of the constant voltage charging circuit 13 from E1 to E2. [N3] Since the set voltage of the battery increases, the battery is pulse-charged with the current controlled by the constant current charging circuit. [N4] The timer of the calculating means 11 counts and performs pulse charging for a set time (Ta). [N5] The calculation means 11 switches off the charge control switch SW2 to set the charge current of the battery to zero. [N6] The timer of the arithmetic means 11 counts and holds the charging current at 0 for the set time (Tb). [N7] The battery voltage (E) is input from the voltage detection circuit 12 to the calculation means 11. [N8] The calculating means 11 calculates the charge capacity of the battery from the measured voltage (E). [N9] The display means 15 displays the charge capacity of the battery. [N10] The arithmetic means 11 switches the switch SW1 of the constant current charging circuit 14 to change the reference voltage from E2 to E1.
And [N11] The calculating means 11 includes a charge control switch SW2
Is turned on. In this state, the main charging of the battery is restarted. [N12] The arithmetic means 11 determines whether or not a predetermined time (Tc) has elapsed, and when the set time has elapsed, loops to the step of [N2] and suspends the main charging. Thereafter, the steps [N1] to [N12] are repeated to charge while displaying the charge capacity of the battery.

In the above flow chart, the battery voltage is measured with the charging current of the battery set to 0 during the main charging suspension time. As shown by the chain line in FIG. 5, the charge control switch SW2 has three contacts, the A contact is a battery, and the B contact is a current limiting resistor R.
If the C contact is opened to the battery via I, the battery voltage can be measured by applying a small current during the main charging pause time. In this case, the battery is charged according to the flowchart shown in FIG. In this flowchart, [N1] to [N4] are the same as the flowchart of FIG. [N5] The calculating means 11 sets the charge control switch SW2 to C
Switch to contact. In this state, the charging current of the battery temporarily becomes zero. [N6] The timer of the calculating means 11 is equal to the set time (Td)
Determine if it has passed. [N7] The calculating means 11 sets the charge control switch SW2 to B
Switch to contact. In this state, the battery is charged with a very small current. [N8] The battery voltage is calculated from the voltage detection circuit 12 to the calculation means 1
1 is input. [N9] The calculation means 11 compares the input battery voltage with the previous measured value to measure the lowest voltage. [N10] The calculating means 11 calculates the charge capacity of the battery from the lowest voltage. [N11] The display means 15 displays the charge capacity of the battery. [N12] The calculating means 11 sets the changeover switch SW1 to E1
Switch to the side. [N13] The calculating means 11 includes a charge control switch SW2
To the A contact to start main charging. [N14] The arithmetic means 11 determines whether or not a predetermined time has elapsed (Tc), and when the set time has elapsed, loops to the step of [N2] and suspends the main charging of the battery. Thereafter, the steps [N2] to [N14] are repeated to charge while displaying the charge capacity of the battery.

In the flowchart shown in FIG. 7, in steps [N5] and [N6], the charging current of the battery is set to 0 at one time of the main charging suspension time, and thereafter the battery is charged with a very small current. However, the steps of N5 and N6 can be omitted, and the charging capacity can be calculated by measuring the minimum voltage of the battery without setting the charging current to 0 during the main charging suspension time.

Further, in steps [N5] and [N6], the battery can be discharged and then charged with a small current to measure the minimum voltage. In this case, the steps [N5] to [N6] in the flowchart shown in FIG. 7 are changed as follows. [N5] After the calculation means 11 switches off the charge control switch SW2, it turns on the discharge switch SW3. [N6] The timer of the calculating means 11 counts, and the battery is discharged at a predetermined current for a set time (Tb).

Further, according to the charging capacity display method of the present invention, the charging capacity can be calculated by measuring the battery voltage when the slope at which the voltage of the battery drops below a certain level during the main charging pause time. . As shown in FIG. 3, after the pulse charging is stopped, the battery voltage gradually decreases. At this time, the slope at which the battery decreases, that is, ΔV / ΔT indicating the voltage change value gradually decreases. It is also possible to calculate the charge capacity by measuring the battery voltage when ΔV / ΔT falls below a certain value.

In this case, [N] in the flowchart of FIG.
6] and [N7] are changed as shown in FIG. [N6] The voltage detection circuit 12 detects the battery voltage and inputs the battery voltage to the calculation means 11. [N7] The calculating means 11 compares the input battery voltage with the previous measured value to detect whether the voltage has increased or decreased. When the voltage is increased, also increases the current measurement voltage than the previous measurement voltage, the _{E n -E n-1> 0} . When this condition is satisfied, the battery voltage becomes the minimum voltage. Computing means 11 detects the E _n as the lowest voltage.

Embodiment 2 A non-aqueous secondary battery such as a lithium ion secondary battery is charged in the following manner using the current and voltage curves shown in FIG. The main battery is charged by charging the battery with a constant current at a constant current. The main charging is suspended every predetermined time. In the main charging suspension time, the battery current is set to 0 after the first pulse discharge. After a certain time elapses after the battery current is set to 0, the voltage of the battery is detected to calculate the charge capacity, and thereafter, the mode is switched to the main charge. When the battery approaches full charge, it switches to constant voltage charging. Also in this state, the main charging is suspended at a constant cycle to provide a main charging suspension time, and at the end of the main charging suspension time, the battery voltage is measured to calculate the charging capacity.

When the battery is charged at a constant current and when charged at a constant voltage, the battery is pulse-discharged at a constant current. In the main charging pause time, when the pulse discharge is performed, the voltage of the battery once drops as shown in FIG. 2 and then rises to the position shown by the broken line.

FIG. 9 shows a charging circuit for calculating a charging capacity by performing pulse discharge at the beginning of the main charging suspension time. The circuit shown in FIG.
The circuit is the same as the circuit shown in FIG. 5 except that W3 and the discharge resistor RL are connected. The discharge switch SW3 is controlled by the calculating means 11. Although a resistor can be used as the discharge resistor RL, a constant current circuit (not shown) is preferably used. The constant current circuit has a feature that pulse discharge can be performed at a constant current regardless of the voltage of the battery. However, even if a resistor is used as the discharge resistor RL, the voltage of the battery is substantially constant, so that pulse discharge can be performed with a substantially constant current.

This charging circuit charges a non-aqueous secondary battery such as a lithium ion secondary battery according to the flowchart shown in FIG. This flowchart charges the non-aqueous secondary battery with the voltage and current characteristics shown in FIG. [N1] Start charging. In this state, the battery is charged at a constant current first, and then becomes a constant voltage charge when the battery approaches full charge. [N2] After the calculation means 11 turns off the charge control switch SW2, it turns on the discharge switch SW3. [N3] The battery is disconnected from the power supply 1 and connected in parallel with a discharge resistor RL to be pulse-discharged. [N4] The timer of the calculating means 11 counts, and performs pulse discharge for the set time (Ta). [N5] The arithmetic means 11 switches off the discharge switch SW3 to set the charging current flowing through the battery to zero. [N6] The timer of the arithmetic means 11 counts and holds the charging current at 0 for the set time (Tb). [N7] The battery voltage (E) is input from the voltage detection circuit 12 to the calculation means 11. [N8] The calculating means 11 calculates the charge capacity of the battery from the measured voltage (E). [N9] The display means 15 displays the charge capacity of the battery. [N10] The calculating means 11 includes a charge control switch SW2
Is turned on, and the battery is connected to the power supply 1. In this state, the main charging of the battery is restarted. [N11] The calculating means 11 determines whether or not a predetermined time (Tc) has elapsed, and when the set time has elapsed, loops to the step of [N2] and suspends the main charging. Thereafter, the steps [N1] to [N11] are repeated to charge the battery while displaying the charge capacity of the battery.

In the above flowchart, the battery voltage is measured with the charging current of the battery set to 0 during the main charging suspension time. As described above, the method of performing pulse discharge at the beginning of the main charging suspension time can also perform charging by applying a small current when measuring the battery voltage, in the same manner as the method of performing pulse charging. In order to realize this, as shown by the dashed line in FIG. 9, the charge control switch SW2 has three contacts, the A contact is a battery, and the B contact is a current limiting resistor RI, as shown by the dashed line in FIG. The C contact is opened to the battery via.
When the battery voltage is measured, the charge control switch SW2 is connected to the contact B, and a small current is applied to the battery to measure the battery voltage.

In the above-described charging capacity display method, the battery is pulse-charged or pulse-discharged at a constant current during the main charging suspension time. As described above, the method of pulse charging or pulse discharging with a constant current can calculate and display the charging capacity of the battery most accurately. However, the present invention does not specify a method for making the current of pulse charging or pulse discharging always constant. The method of the present invention comprises the steps of:
The measurement conditions of the battery voltage during the main charging suspension time are made more uniform. Therefore, the ideal method is to make the current of pulse charge and pulse discharge constant, but even if the battery is not constant, the calculation error of the charge capacity with respect to the battery voltage is reduced by the pulse charge and pulse discharge. it can.

[0040]

According to the method of the present invention for displaying the charge capacity of a battery during charging, the battery is pulse-charged or pulse-discharged at the beginning of the main charging pause, and then the battery voltage is measured to calculate the charge capacity. In the method of pulse charging at the beginning of the main charging pause time, even if the battery is close to full charge and the charging current decreases, the main charging is paused after pulse charging with a predetermined current, so the main charging was paused. Instantaneous current change can be reduced. For this reason, regardless of the charge amount of the battery, after charging with a predetermined current, charging is stopped, the voltage is measured, and the charge capacity is calculated from the measured voltage. Therefore, there is a feature that the state of the battery immediately before measuring the battery voltage can be made more uniform, and the charged capacity can be accurately calculated from the voltage measurement. Also, in order to make the conditions immediately before the voltage measurement uniform, the battery is charged. However, since the charging time is short by pulse charging, the battery is not overcharged. Also, the method of pulse discharging at the beginning of the main charging pause time can equalize the state of the battery immediately before measuring the battery voltage, as in the method of pulse charging, and calculate the charging capacity accurately from the battery voltage. There are features that can be done.

Further, according to the charging capacity display method of the present invention, the state of the battery immediately before measuring the voltage can be made uniform by pulse charging or pulse discharging. There are features that can be done. Therefore, the charging capacity display method of the present invention has a feature that the charging capacity can be accurately calculated and displayed without extending the charging time as compared with the conventional method.

[Brief description of the drawings]

FIG. 1 is a graph showing voltage and current characteristics for charging a battery by a method according to an embodiment of the present invention.

FIG. 2 is a graph showing voltage and current characteristics for charging a battery by another method according to the embodiment of the present invention.

FIG. 3 is a graph obtained by enlarging a voltage change of the graph shown in FIG. 1;

FIG. 4 is a graph showing an example of a charging capacity with respect to a voltage of a battery.

FIG. 5 is a block diagram of a charging circuit used in the charging method of the present invention.

FIG. 6 is a flowchart for charging a battery by the charging circuit shown in FIG. 5;

FIG. 7 is a flowchart showing another method for charging a battery by the charging circuit shown in FIG. 5;

8 is a flowchart showing still another method of charging a battery by the charging circuit shown in FIG.

FIG. 9 is a block diagram showing another charging circuit used in the charging capacity display method of the present invention.

FIG. 10 is a flowchart for charging a battery by the charging circuit shown in FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power supply 2 ... Charge control means 3 ... Input filter 4 ... Rectifier circuit 5 ... Switching part 6 ... Conversion transformer 7 ... Rectification smoothing circuit 8 ... PWM control circuit 9 ... Photocoupler 10 ... Output adjustment circuit 11 ... Calculation means 12 ... Voltage Detection circuit 13: Constant voltage charging circuit 13A: Differential amplifier 14: Constant current charging circuit 14A: Differential amplifier 15: Display means SW1: Changeover switch RI: Current limiting resistance SW2: Charge control switch RL: Discharge resistance SW3: Discharge switch RS: current detection resistor

Claims (1)

(57) [Claims] 1. A charge capacity display method for providing a main charge pause time at a predetermined cycle during charging, detecting a battery voltage during the main charge pause time, and calculating and displaying a battery charge capacity from the detected battery voltage. Pulse charging or discharging during the main charging pause time,
A method for displaying the charge capacity of a battery during charging, comprising detecting the voltage of the battery and calculating and displaying the charge capacity of the battery.