JP3237293B2 - Method and apparatus for charging sealed lead-acid battery - 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 and an apparatus for charging a sealed lead-acid battery in which a pulse-like charging current is supplied to reduce generation of gas at the end of charging.

[0002]

2. Description of the Related Art When a battery voltage during charging is detected and a battery voltage reaches a terminal voltage, a pulse-like charging current, that is, a charging pulse is supplied, and the interval between pulses is increased as charging progresses. There is known a pulse charging method (or a jog charging method) in which the average charging current is controlled so as to reduce the generation of gas during charging. In a conventionally known method of charging a sealed lead-acid battery employing this method, the interval between charging pulses, that is, the pulse generation cycle, is gradually increased. At the same time, a method of changing the pulse width has been proposed.

[0003]

In the conventional charging method,
The interval between the charging pulses, that is, the increment rate of the pulse generation cycle and the reduction rate of the pulse width are determined with a margin so as to reliably suppress the generation of gas. Therefore, the cycle may be longer than necessary, and the charging efficiency at the end of charging is not always good. An object of the present invention is to provide a method and an apparatus for charging a sealed lead-acid battery that can minimize generation of gas without reducing charging efficiency at the end of charging as much as possible.

[0004]

SUMMARY OF THE INVENTION The invention of claim 1 is directed to a method of charging a sealed lead-acid battery in which pulse charging is performed using a charging pulse at the end of charging. In the present invention, each time a charge pulse is generated, the rate of change of the charge voltage during the period in which charging is performed by the charge pulse is measured. Then, the charging pulse is generated at a cycle of 10 msec or more, and every time the voltage change rate becomes equal to or more than the set value, the average current value of the charging current supplied by the charging pulse generated thereafter is reduced. The method of reducing the average current value is arbitrary, such as changing the generation cycle of the charging pulse, changing the pulse width of the charging pulse, and the like. According to the second and seventh aspects of the present invention, the measurement of the voltage change rate is started after a predetermined time has elapsed since the generation of the charging pulse. Claim 3
According to the invention, every time the voltage change rate becomes equal to or more than the set value, the generation cycle of the charging pulse is increased in order to reduce the average current value of the charging current supplied by the charging pulse generated thereafter. According to a fourth aspect of the present invention, in the requirement of the third aspect, the pulse width of the charging pulse is changed while the pulse width of the charging pulse is kept constant. In the present invention, each time the voltage change rate becomes equal to or more than the set value, the cycle of the charging pulse generated thereafter is set to 1
Is changed to a cycle of a value obtained by multiplying the reference cycle by the number obtained by adding. In this case, it is preferable that the charging pulse is generated after the charging is stopped to form one cycle. According to a sixth aspect of the present invention, there is provided an apparatus for carrying out the method according to the fourth aspect of the present invention, wherein the switch circuit is inserted into a charging circuit and is turned on / off according to a control signal, and detects a charging voltage. A sealed lead-acid battery including a voltage detector and a charge control device that outputs a control signal in accordance with the output of the voltage detector, wherein the charge control device performs pulse charging using a charge pulse having a constant pulse width at the end of charging. Of the charging device. According to the present invention, the control signal generating means for pulse charging of the charging control device includes a voltage change rate detecting means, a cycle change command generating means, a cycle change command output number accumulating means, and a control signal generating means. The voltage change rate detecting means measures the voltage change rate of the charging voltage during the period when charging is performed by the charging pulse every time the charging pulse is generated. The cycle change command generation means outputs a cycle change command when the change rate detected by the voltage change rate detection means becomes larger than a set value. The cycle change command output number accumulating means accumulates the number of times that the cycle change command has been output from the cycle change command generation means. The control signal generating means adds 10 msec to the number obtained by adding 1 to the cumulative value accumulated by the cycle change command output number accumulating means.
A control signal for generating a charge pulse is generated in a cycle of a value obtained by multiplying the above-described reference cycle. In the invention of claim 8,
Each time the voltage change rate becomes equal to or greater than the set value, the pulse width of the charging pulse is gradually reduced in order to reduce the average current value of the charging current supplied by the charging pulse generated thereafter.

[0005]

According to the present invention, it is determined from the voltage change rate of the charging voltage whether or not the gas generation state is approached. In this case, the present invention measures the voltage change rate of the charging voltage during the period in which charging is performed by the charging pulse, so that more accurate determination can be made. This is because if the voltage change rate from the state before charging by the charge pulse is used as a reference, this voltage change rate is not only the polarization caused by gas generation but also the polarization due to internal resistance such as electrolyte resistance and the active material. This is because polarization due to the charging reaction is included, and the determination error of the gas generation state increases.

The reason why the reference cycle of the charging pulse is set to 10 msec or more (100 Hz or less) is to make it easy to detect the magnitude of polarization due to gas generation. FIG.
Indicates pulse charging in the constant voltage region (curve A), and pulse charging immediately after the change from the constant current region to the constant voltage region (curve B).
And pulse charging in the constant current region (Curve C)
5 shows changes in the pulse frequency and the absolute value of the internal impedance of the battery. It is believed that an increase in internal impedance indicates an increase in polarization resistance that occurs during gas generation. Therefore, from this result, the frequency of the pulse is set to 10
If the frequency is 0 Hz or less, that is, if the pulse period is 10 msec or more, the rate of change of the internal impedance increases, so that the polarization caused by gas generation can be accurately determined.

As in the first aspect of the present invention, each time a rate of change of voltage equal to or higher than a set value is measured during the charging period by the charging pulse, the average charging current of the current supplied by the charging pulse is reduced from before. Suppressing the generation of gas eliminates the need to make the cycle longer than necessary as in the past,
The charging efficiency at the end of charging can be improved.

When the measurement of the voltage change rate is started after a predetermined time has elapsed since the generation of the charge pulse, the voltage change rate from the state before the generation of the charge pulse is measured. Therefore, it is possible to reliably prevent the determination error of the gas generation state from increasing.

If the average charging current is reduced by increasing the generation cycle of the charging pulse as in the third aspect of the invention, the control is easy.

According to the fourth aspect of the present invention, since the pulse width of the charging pulse is fixed and the cycle of the charging pulse is increased in proportion to the number of times that the voltage change rate exceeds the set value, the charging pulse can be simply and efficiently obtained at the end of charging. Pulse charging can be performed.

According to a fifth aspect of the present invention, in the case of implementing the fourth aspect of the present invention, if the charging pulse is generated after the charging is stopped and forms one cycle, the voltage change rate exceeds the set value. Then, the cycle can be changed immediately from the charging pulse generated immediately thereafter.

According to the invention of claim 6, claims 3 and 4 are provided.
An apparatus that can easily carry out the method of the present invention can be provided.

If the average charging current is reduced by gradually decreasing the pulse width of the charging pulse as in the invention of claim 8, control is easy.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1A shows a basic configuration of an apparatus for implementing the method of the present invention. In the figure, 1 is a DC power supply, 2 is a current control unit, 3 is a diode, 4 is a sealed lead-acid battery, 5 is a voltage detector, and 6 is a charging control device including a microprocessor. The current control unit 2 is configured to include a switch circuit that is inserted into the charging circuit and that is turned on / off in response to a control signal. The voltage detector 5 is configured to include a voltage detection unit and an analog-digital converter,
The voltage detector detects the charging voltage, that is, the lead storage battery, that is, battery
Terminal voltage, and the detected analog value is
It is converted to a digital value by a digital converter and output. The charging control device 6 is configured to perform constant-current charging until the end of charging, and to perform pulse charging at a constant voltage when the end of charging is detected.

FIG. 1B shows an example of the configuration of the charging control device 6 of the embodiment for increasing the period of the charging pulse.
The terminal voltage determining means 61 activates the constant current charging control signal generating means 62 until the voltage detected by the voltage detector 5 reaches a predetermined terminal voltage. The constant current charging control signal generating means 62 outputs a control signal for performing constant current charging to the current control unit 2 until the terminal voltage determining means 61 detects the terminal voltage. When the terminal voltage determining means 61 detects the terminal voltage, the constant current charging control is stopped, and the pulse charging control signal generating means (63 to 66) starts pulse charging. The voltage change rate detecting means 63 measures the voltage change rate of the charging voltage during the period when charging is performed by the charge pulse every time the charge pulse is generated. Specifically, the output of the voltage detector 5 is taken at a predetermined sampling period (t) during the period in which the charging pulse is generated, and the voltage change rate (d
V / dt). Note that this sampling is started after a predetermined time has elapsed since the generation of the charging pulse. The cycle change command generation means 64 outputs a cycle change command when the rate of change detected by the voltage change rate detection means 63 becomes larger than a set value. When detecting that the voltage change rate has exceeded the set value within the period of one charging pulse, the cycle changing command generating means 64 outputs the cycle changing command only once within the period of the charging pulse. The cycle change command output number accumulating means 65 accumulates the number of times that the cycle change command is input, and outputs the accumulated value n (positive integer) to the control signal generating means 66.
Output to The control signal generating means 66 sets the accumulated value n of the cycle change command output number accumulating means 65 to a reference cycle T of 10 msec or more having the charging stop period S from the time when the terminal voltage determining means 61 determines the terminal voltage Vc. A charging pulse P having a constant pulse width W is generated in a cycle obtained by multiplying a number (n + 1) obtained by adding one. That is, a charge pulse is generated in the reference cycle T until the cycle change command is output, and every time the cumulative value n of the cycle change command output number accumulating means 65 increases due to the generation of the cycle change command, the generation cycle is changed to the reference cycle T. (N + 1)
The charging pulse is output after being doubled.

FIG. 2 schematically shows a change in the cycle of the charging pulse as the cumulative value n increases.

In FIG. 1B, the final voltage determination means 67
Detects that the battery voltage has reached a predetermined end-of-charge voltage, outputs a charge stop command to the control signal generation means 66 to stop pulse charging. FIG. 3 is a flowchart showing an algorithm of a program for operating the microprocessor of the charge control device 6. In FIG.
Is a set value for determining the magnitude of the voltage change rate.

FIG. 4 shows a small sealed lead storage battery (single cell).
FIG. 7 is a diagram schematically showing charging characteristics when the battery is charged at a constant current of 1 C up to 2.5 V and pulse charging is performed under the conditions described later in the later stage of charging. This example will be specifically described with reference to FIG. FIGS. 5A and 5B are enlarged views of the state of the charging current and the battery voltage immediately after the battery voltage V exceeds the terminal voltage Vc (2.5 V) and the pulse charging is started. 100 from the control signal generating means 66
At a reference period T of msec, a charging pulse having a constant pulse width W (98 msec) is output after a stop period S of 2 msec. The voltage change rate detecting means 63 is 1 msec as shown in FIG.
The battery voltage Vp is fetched from the voltage detector 5 in accordance with the sampling pulse of the sampling period, and the period change command generation means 64 determines that the voltage change rate becomes 30 mV / sec or more during the period in which the charging pulse P is generated. Output cycle change command. The sampling is performed for a predetermined time t (1 msec in this embodiment) after the generation of the charging pulse P.
Start after elapse.

When the cycle change command is input to the cycle change command output number accumulating means 65 and the accumulated value n becomes 1, the control signal generating means 66 sets the generation cycle of the next charging pulse P to twice the reference cycle, ie, 200 msec. change. FIGS. 5D and 5E schematically show the state of the charging pulse and the battery voltage when n = 1. The pulse width of the charging pulse P is 98 ms
Since ec is constant and the stop period S is provided before the charging pulse P, the stop period S is 102 msec. FIG. 5 (D)
This is the same as omitting every other charge pulse generated in the next reference cycle. FIG.
The pulse P 'shown by a broken line in (D) is a thinned pulse. As shown by the broken line in FIG. 5E, even if the cycle is twice the reference cycle, if the voltage change rate when charging is performed with the next charging pulse is 30 mV / sec or more,
The cycle change command is output again, and the cycle is tripled, that is, the number of pulses to be thinned out becomes two.

For comparison, the same battery was charged at a constant current of 1 C with a charging time of 1.5 hours to a set voltage of 2.5 V at a constant voltage. When the amount of gas generated at that time was measured, it was confirmed that four times as much gas was generated as when charging was performed by the method of the above specific example. In addition, when the known pulse charging method was compared with the method of the present invention, it was confirmed that the amount of gas generated was smaller when the method of the present invention was used.

When a cycle life test was performed under the same conditions using the constant voltage charging method, the known pulse charging method, and the charging method of the present invention, the results shown in FIG. 6 were obtained. The battery used was 6 V at 1.2 AH, and the amount of discharged electricity was 1
At C, the discharge end voltage is 1.6 V / cell, and the amount of electricity charged is 1 C
, The final charging voltage was 2.5 V / cell, and the charging time was 1.5 hours. In FIG. 6, a curve a shows a characteristic when the battery is charged by the method of the above embodiment of the present invention, and a curve b shows that the charging is performed by changing the cycle at a fixed rate from 10 msec to 100 msec with a constant pulse width. A characteristic when charging is performed by a conventional pulse charging method, and a curve c indicates a characteristic when charging is performed by a constant voltage charging method. Comparing these curves a to c, it can be seen that the life is longer when the method of the present invention is used than in the conventional method.

In the above embodiment, the cycle is made n + 1 times the reference cycle when the cycle variable command is output n times.
Depending on the value of the reference cycle, the cycle is set to m (n + 1) of the reference cycle
It may be doubled. Note that m is a positive integer.

FIG. 7 shows a configuration of a charging control device 6 according to an embodiment in which the average value of the charging current is reduced by changing the pulse width while keeping the period of the charging pulse constant. This charge control device 6 is the same as the charge control device 6 shown in FIG.
The difference is that a pulse width change command generating means 68 is provided in place of the cycle change command generating means 64 and the cycle change output number accumulating means 65. The pulse width change command generation means 68 issues a command to gradually or stepwise decrease the pulse width of the charge pulse every time the voltage change rate during the generation of the charge pulse becomes greater than or equal to the set value. 66 is output. The rate of decreasing the pulse width is arbitrary. A flowchart of an algorithm when this charge control device is realized using a microprocessor is as shown in FIG. FIG. 9 shows an operation waveform when the pulse charging operation is performed when the present embodiment is specifically executed under basically the same conditions as when the operation waveform of FIG. 5 is obtained. FIGS. 9A to 9C are FIGS.
The description is omitted because it is the same as (C). In this embodiment, the voltage change rate during the generation of the charging pulse is 30 m.
When V / sec or more, the pulse width of the charging pulse is reduced. FIG. 9D shows a charging pulse P ′ in which the pulse width is reduced with a constant period, and FIG. 9E shows a change in the charging voltage when the pulse width of the charging pulse is reduced. . If the voltage change rate is still 30 mV / sec or more even if the pulse width is reduced, the pulse width of the charging pulse is further reduced. Thereafter, this operation is repeated until the battery voltage reaches the final voltage.

In the above two embodiments, the average current value of the charging current is reduced by changing the period or pulse width of the charging pulse. However, the charging is performed by changing both the period and the pulse width of the charging pulse. The average current value of the current may be reduced, the voltage or current of the charging pulse may be reduced, and a method and means for reducing the average charging current supplied by the charging pulse are arbitrary.

[0025]

According to the first aspect of the present invention, the rate of change of the charging voltage during the period of charging by the charging pulse having a cycle of 10 msec or more is measured. It can be measured reliably. Further, in the present invention, each time a voltage change rate equal to or higher than a set value is measured during the charging period by the charging pulse, the generation of gas is suppressed by lowering the average current value of the charging current supplied by the charging pulse than before. Therefore, the cycle is not lengthened more than necessary as in the related art, and the charging efficiency at the end of charging can be improved.

According to the second and seventh aspects of the present invention, when the measurement of the voltage change rate is started after a predetermined time has elapsed after the generation of the charging pulse, the measurement of the voltage change rate from the state before the generation of the charging pulse is performed. Therefore, there is an advantage that it is possible to reliably prevent the determination error of the gas generation state from increasing.

According to the third aspect of the present invention, since the average charging current is reduced by increasing the generation cycle of the charging pulse, there is an advantage that the control becomes easy.

According to the fourth aspect of the present invention, since the pulse width of the charging pulse is fixed and the cycle of the charging pulse is increased in proportion to the number of times that the voltage change rate exceeds the set value,
There is an advantage that pulse charging at the end of charging can be performed simply and efficiently.

According to the fifth aspect of the present invention, when the second aspect of the present invention is implemented, the charging pulse is generated after the charging is stopped to form one cycle, so that the voltage change rate is equal to the set value. When it exceeds, the cycle can be changed immediately from the charging pulse generated immediately after that.

According to the invention of claim 6, claims 1 and 2
An apparatus that can easily carry out the method of the present invention can be provided.

According to the eighth aspect of the present invention, since the average charging current is reduced by reducing the pulse width of the charging pulse, there is an advantage that control becomes easy.

[Brief description of the drawings]

FIG. 1A is a diagram showing a basic configuration of a device for implementing a method of the present invention, and FIG. 1B is a block diagram showing an example of a charge control device of FIG.

FIG. 2 is a diagram schematically showing a change in a cycle of a charging pulse with an increase in a cumulative value.

FIG. 3 is a flowchart illustrating an algorithm of a program when the charge control device is implemented using a microprocessor.

FIG. 4 is a diagram for explaining an outline of an operation of the embodiment of FIG. 1;

FIG. 5 is a waveform chart for explaining the operation of the charge control device of FIG. 1 (B).

FIG. 6 is a diagram showing life characteristics of a battery when the charging method of the present invention and a conventional charging method are used.

FIG. 7 is a block diagram showing a configuration of a charge control device according to another embodiment of the present invention.

8 is a flowchart showing an algorithm of a program when the charge control device of FIG. 7 is realized using a microprocessor.

FIG. 9 is a waveform chart for explaining the operation of the charge control device of FIG. 7;

FIG. 10 is a diagram showing the relationship between the frequency of a charging pulse and the internal impedance of a battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2 Current control part 3 Diode 4 Sealed lead storage battery 5 Voltage detector 6 Charging control device 61 Terminal voltage determination means 62 Constant current charging control signal generation means 63 Voltage change rate detection means 64 Cycle change command generation means 65 Period change command output count accumulating means 66 Control signal generating means 67 Terminal voltage determining means 68 Pulse width change command generating means

Continuation of front page (56) References JP-A-54-25437 (JP, A) JP-A-4-123771 (JP, A) JP-A-61-193380 (JP, A) JP-A-1-107625 (JP) JP-A-55-41191 (JP, A) JP-A-50-95745 (JP, A) JP-A-2-254931 (JP, A) JP-A-63-157626 (JP, A) 61-121722 (JP, A) JP-A-3-145935 (JP, A) JP-B-44-32134 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 7/00 -7/10 H01M 10/44

Claims (8)

(57) [Claims] 1. A method for charging a sealed lead-acid battery that performs pulse charging using a charging pulse at the end of charging, wherein a charging voltage during a period in which charging is performed by the charging pulse each time the charging pulse is generated. The voltage change rate is measured, and the charge pulse is generated at a cycle of 10 msec or more. Each time the voltage change rate becomes equal to or more than the set value, the average current value of the charge current supplied by the charge pulse generated thereafter A method for charging a sealed lead-acid battery, characterized in that the charge is reduced. 2. The method for charging a sealed lead-acid battery according to claim 1, wherein the measurement of the voltage change rate is started when a predetermined time has elapsed after the generation of the charging pulse. 3. A method for charging a sealed lead-acid battery that performs pulse charging using a charging pulse having a constant pulse width at the end of charging, wherein charging is performed by the charging pulse each time the charging pulse is generated. Measure the voltage change rate of the charging voltage during, generate the charging pulse in a cycle of 10 msec or more until the voltage change rate is equal to or more than a set value, every time the voltage change rate becomes equal to or more than the set value A method for charging a sealed lead-acid battery, characterized by increasing the period of the charging pulse generated thereafter. 4. A method of charging a sealed lead-acid battery in which pulse charging is performed using a charging pulse having a constant pulse width at the end of charging, wherein charging is performed by the charging pulse each time the charging pulse is generated. Measuring the voltage change rate of the middle charging voltage, generating the charging pulse at a reference cycle of 10 msec or more until the voltage change rate becomes equal to or more than a set value, and every time the voltage change rate becomes equal to or more than the set value. The cycle of the charge pulse generated thereafter is changed to a cycle of a value obtained by multiplying the reference cycle by a number obtained by adding 1 to an accumulated value of the number of times that the voltage change rate becomes equal to or more than the set value and charging. A method of charging a sealed lead-acid battery. 5. The method for charging a sealed lead-acid battery according to claim 4, wherein the charging pulse is generated after the charging is stopped and forms one cycle. 6. A switch circuit inserted into a charging circuit and controlled to be turned on / off according to a control signal, a voltage detector for detecting a charging voltage, and outputting the control signal according to an output of the voltage detector. A charge control device for charging a sealed lead-acid battery, wherein the charge control device performs pulse charging using a charge pulse having a constant pulse width at the end of charging, wherein control for pulse charging of the charge control device is provided. The signal generation means detects the voltage change rate detection means for measuring the voltage change rate of the charging voltage during the period of charging by the charge pulse every time the charge pulse is generated, and the voltage change rate detection means A cycle change command generating means for outputting a cycle change command when the rate of change becomes greater than a set value; and a cycle for accumulating the number of times the cycle change command is output from the cycle change command generating means. And a control for generating the charging pulse in a cycle of a value obtained by multiplying a value obtained by adding 1 to the accumulated value accumulated by the cycle change command output number accumulating means and a reference cycle of 10 msec or more. A charging device for a sealed lead-acid battery, comprising: a control signal generating means for generating a signal. 7. The charging device for a sealed lead-acid battery according to claim 6, wherein the voltage change rate detecting means measures the voltage change rate from a point in time when a predetermined time has elapsed since the rise of the charging pulse. 8. A method for charging a sealed lead-acid battery in which pulse charging is performed using a charging pulse at the end of charging, wherein the charging is performed every time the charging pulse is generated until the voltage change rate exceeds a set value. The rate of change of the charging voltage during the period of charging by the pulse is measured, and the charging pulse is generated in a cycle of 10 msec or more, and is generated every time the rate of voltage change becomes equal to or more than the set value. A method for charging a sealed lead-acid battery, wherein the pulse width of the charging pulse is gradually reduced.