JPH0845555A - Charging method - Google Patents

Abstract

PURPOSE:To correctly determine whether to do uniform charging or to do normal charging. CONSTITUTION:A charging characteristic curve between a starting point and the point of inflection is divided into four steps, namely a first step up to a voltage value V1 equivalent to one half of the quantity of electricity charged, a second step up to the point of inflection, and a third and a fourth step representing each one half of charging from the point of inflection to the completion of charging. Based on these steps and charging time, a charging factor is determined, where the greater it is the closer each charging step comes to its end, and every time when charging is over, the charging factor applicable to its charging is added to a charging factor accumulated value accumulated so far. In the following charging, normal charging is performed if the accumulated value is found to have been less than a specified value, and uniform charging is performed if the accumulated value is found to have been in excess of the specified value. And when uniform charging is suspended halfway, the value shall be one from which the accumulated value accumulated so far is deducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to charging a storage battery of an electric vehicle such as a battery fox lift, and more particularly to a charging method for automatically determining whether normal charging or equal charging.

[0002]

2. Description of the Related Art When a storage battery is charged, if so-called normal charging is repeatedly performed, there is a slight difference in performance among a plurality of cells constituting the storage battery, so that the charging state varies. . For this reason, when charging is performed a proper number of times, so-called uniform charging is performed so that the performance of each cell is equalized by overcharging.

Conventionally, a user operates a switch for selecting whether to perform normal charging or uniform charging based on experience and intuition. Further, it has been proposed to count the number of times of normal charging and automatically perform uniform charging when the number of times reaches a predetermined value (Japanese Patent Laid-Open No. 62-62).
No. 123927). Normal charging is the time from the start of charging until the terminal voltage of the storage battery reaches a predetermined value, the so-called initial charging time, and the charging time after reaching the predetermined voltage according to the measured time (the final charging time) After setting, the charging is completed when the set time elapses. on the other hand,
Equal charging is to charge a fixed amount of time more than the end charging period of normal charging.

[0004]

When the user determines whether the charging is normal charging or even charging, the optimum charging is not always selected. If the equal charge is performed earlier, the electrolyte will decrease more quickly, and the life of the storage battery will be shortened. On the contrary, if the uniform charging is delayed, the electric capacity of the storage battery cannot be used sufficiently, which shortens the life of the storage battery. Therefore, in order to sufficiently extend the life of the storage battery and obtain a sufficient electric capacity, it is necessary to appropriately select normal charging and uniform charging. However, it is difficult for the user to do this with experience and intuition.

The amount of discharge of the storage battery is different each time, and the amount of discharge varies depending on, for example, whether the storage battery is operated all day, only half a day, or only one hour. There are various charge amounts when the battery is fully charged the next day after the work is completed. Therefore, it is not always possible to select an appropriate charging mode when determining whether to perform uniform charging or normal charging only by the number of times of charging as in the conventional case.

Even when the charging is completed before the completion of the charging, there are variations in the charging given to each cell of the storage battery depending on whether the charging is stopped immediately before the completion of the charging or when the charging is stopped after only a slight charge. The difference between
Therefore, it is not always appropriate to judge the charging mode by counting only the number of times of charging.

[0007]

According to the present invention, the charging process from the end-of-charging state to the full charge is divided into a plurality of charging processes, and a larger charging coefficient is given to each charging process, which is the final charging process. When the charging is set in advance and the charging is completed, the charging coefficient corresponding to the charging process at the end is cumulatively added to the charging coefficient up to that point, and the cumulative addition value is equal to or less than a predetermined value If it is determined that the charging is equal, and the charging is performed, the cumulative addition value is set to 0.

The above-mentioned setting of the charging coefficient is made larger not only at the charging stage but also as the charging time, that is, the charging amount (discharging amount) increases. Furthermore, if the charging is terminated during the uniform charging, the cumulative addition value is decreased. Further, the charging of the result determined by the cumulative addition value is automatically executed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a general structure of a charger. The charger is connected to an AC power source 11, for example, a commercial power source, by an outlet 12.
2 is connected to a transformer 14 through an electromagnetic switch 13, is normally lowered to an appropriate voltage by the transformer 14, AC power is supplied to the rectifier circuit 15, and power converted to DC by the rectifier circuit 15 is supplied to the storage battery 16. The battery 16 is supplied and the storage battery 16 is charged. In this case, when AC power is input from the outlet 12, it is detected by the AC detection circuit 17, and this is given to the control unit 18. The controller 18 is composed of a microcomputer, and when a detection signal of its AC power input is given, the electromagnetic switch 1 is connected through the interface 19.
3 is turned on to start charging. The terminal voltage of the storage battery 16 is detected by the voltage detection circuit 22, and the control unit 18 controls charging according to the state of the voltage. In addition, the state of charge is given to the display 27 through the interface 15,
The progress of charging is displayed, for example, by lighting the light emitting elements L _{1 to} L ₆ . Further, it is also displayed whether the battery is normally charged or evenly charged. The charging start switch 23 controls the control unit 18 to start charging, and the power from the storage battery 16 is supplied as an operating power supply voltage to each unit through the power supply circuit 21.

In the present invention, the charging process is divided into a plurality of charging stages. That is, as shown in FIG. 2A, the discharge end state, that is, the maximum discharge state allowed for the storage battery, and the maximum discharge allowed for which the storage battery becomes defective or the life is shortened by discharging more than that. The limit, the terminal voltage of the storage battery from that state to full charge changes like the curve 29. This is also called a so-called charge characteristic curve. As shown by the curve 29, the terminal voltage gradually increases almost linearly as the charging proceeds from the terminal voltage V ₀ in the discharge termination state, and when reaching a certain point, the terminal voltage rapidly increases and then again. It will be in a state of rising very little. The voltage V _{2 at} which the voltage suddenly rises, which is a so-called inflection point, is known in advance. Normally, the time from the start of charging to the inflection point voltage V ₂ is measured, and for example, about 70% of this time is measured. After the inflection point, the charging is continued for a certain time, and the charging is completed.

When the amount of charge at the voltage V ₀ in the discharge termination state is 0 and the amount of charge at the time of completion of charge is 100, when the charge is reached to the inflection point, the charge is approximately 80% to 90%. The remaining 20% to 10% is done with end-of-life charging. In this example, when the charging process is divided into four charging stages, it is first divided according to whether it is before or after the inflection point, and half the amount of charge up to the inflection point, that is, 40 It is divided into two charging stages from the terminal voltage V ₁ in a state of being charged by 45% to the terminal voltage V ₁ and from V ₁ to V ₂ . This terminal voltage is V ₀
From V ₁ to V ₁ is the charging stage 1, from V ₁ to V ₂ is the charging stage 2, and the period from the inflection point to full charge is divided into halves, the former being the charging stage 3 and the latter being the latter. Is the charging stage 4. For example, if the voltage V ₀ is 48V, V
₁ is 55V, V ₂ is 60V, and it is 64V when the charge is completed.

In this way, the charging process is divided into four charging stages in this example, and the charging coefficient is set according to the charging stage and the charging time, that is, the charging amount in this example. For example, as shown in FIG. 2A, during the charging phase 1, the charging coefficient is changed to C
₀ , the charging coefficient is C ₁ in the charging step 2, the charging coefficient is C ₂ in the charging step 3, the charging coefficient is C ₃ in the charging step 4, and these values are as shown in FIG. 2B. The charging steps are 2, 3, and 4 in the horizontal columns, and the charging time in the vertical columns is divided into three in this example, 0 to 1.5.
It is divided into time, 1.5 to 4.5 hours, and 4.5 hours or more. These times correspond to the charge amount, and as described above, the first 1.
0 to 20 percent charge within 5 hours, 1.
5 to 4.5 hours are 20 to 60 percent charge, and 4.5 hours or more are 60 to 100 percent charge.

The charging coefficient corresponding to this charging section and charging time is determined as shown in FIG. 2B. As can be seen from this, for example, when the charging time is 0 to 1.5 hours, the charging step 2 is 0.15, the charging stage is 3 and 0.2, the charging stage is 4 and 0.3, and the charging coefficient increases as the charging stage approaches the end stage. This also applies to the charging time of 1.5 to 4.5 hours, and becomes larger as the charging stage is closer to the end. On the other hand, if the charging stage is constant, the longer the charging time, the larger the charging coefficient. That is, in the case of the charging stage 2, the charging time is less than 1.5 hours and is 0.15, 1.5 to 4.5.
It increased to 0.3 in 4 hours and 0.7 in over 4 hours. This also applies to the other charging stages 3 and 4, and the longer the charging time, the larger the charging coefficient. This is because if there is little discharge and the charging time is short, or if it is stopped during charging, or if the charging time is short in any case, there will be relatively little variation between cells, but deep discharging will take a long time. This is because the variation between cells becomes large when the battery is charged. Therefore, in that case, the charging coefficient is made large, and when the charging time is short, the charging time is made small. In addition,
As can be seen from this table, the charge coefficient when the battery is fully charged from the discharge end state is 1.0.

Next, in a state where the above-described charging coefficient is predetermined, the corresponding charging coefficient at the end of charging is cumulatively added after charging. An example of the processing will be described with reference to FIG. It is checked whether the AC power supply is connected (S ₁ ),
Are checked charging start switch and the AC power is connected is turned on is (S _2), when charging start switch is turned on the electromagnetic switch 13 is turned ON (S _3), and starts the timer TM _1, and to 0 charge coefficient C (S _4). Thereafter, the connection of the AC power supply is checked whether becomes cross (S _5), further, the charging voltage, i.e., between the storage battery terminal voltage V _B is checked whether becomes V ₁ (S _6).

When the terminal voltage V _B becomes V ₁ , the timer TM ₁ at that time is read out, and the value TM _A , that is, the charging time, and the charging stage of 2 since V _B has become V ₁ are entered. The corresponding _one of the charging coefficients C _{1 of 1} is set as the charging coefficient C (S ₈ ). Checks AC power is turned disconnection in this state (S _9), also the terminal voltage V _B V ₂
It is checked whether or not (S ₁₀ ). When the terminal voltage becomes V ₂ , the value TM _B of the timer TM ₁ is read (S ₁₁ ),
The The charging time of the charging phase 3 reads out the charging coefficient C ₂ corresponding with TM _B as its value the charging coefficient C (S _12). Here, it is determined whether or not the cumulative value K of the charging coefficients up to that time is larger than the predetermined value N (S ₁₃ ), and if the K is smaller than N, the timer TM ₂ is set to TM ₃ , in other words, to set the so-called normal charging (S _14).
On the other hand, when the cumulative charging coefficient K is larger than the predetermined value N, the timer TM ₂ is set to TM ₃ + TM ₄ , that is, the uniform charging is set (S ₁₅ ). Where timer value TM
₃ is usually the value TM read from the previous timer TM _1.
The value of _B is, for example, 70%.

Next, the timer TM ₂ is set in this way and started (S ₁₆ ), it is checked whether the AC power supply is cut off (S ₁₇ ), and the timer value of the timer TM is TM ₃ / 2 when either check (S _18), T
M _3/2 in the charging step when the timer TM ₂ becomes 4
A not become, the charging coefficient C, the charging time in C _3, and sets the corresponding value that is a _{TM B + TM 3/2 (} S 19). After that, it is checked again whether the AC power supply is connected (S ₂₀ ), and the timer TM ₂ sets TM ₃
(S ₂₁ ), and if TM ₃ is reached, it is checked whether it is the equal charge setting state (S ₂₂ ). If it is not the equal charge state, the charge coefficient C at that time, C in this case ₃ is added in addition to the charging coefficient cumulative value K up to that (S _23), and charging termination the electromagnetic switch 13 as an off (S _24).

An AC power source is connected as described above.
Check S_Five, S₉, S₁₁AC power supply
If it is determined that they are not connected, the status of each
Up S_{twenty three}Move to and accumulate the charge coefficient at that time, then
The switch is turned off to end charging. Step S_{twenty two}To
If it is judged to be equal charging, the AC power supply is connected.
Check if there is (S_{twenty five}), If connected, Thailand
Mar TM₂Is TM₃+ TM_FourCheck if it becomes / 2
That is, the additional time TM by equal charge_FourIs half finished
It was checked whether it was done (S₂₆), This period ends
And charge coefficient cumulative value K is rewritten to 1/2 (S₂₇), AC power
Check if the source is connected (S ₂₈),timer
TM₂Is TM₃+ TM_FourCheck if it became
(S₂₉), When this value is reached, the cumulative charging coefficient K is set to 0
Toshi (S₃₀), Step S_{twenty four}Move to the electromagnetic switch
Is turned off to end charging.

Meanwhile, if the AC power is not connected in step S ₂₅ proceeds to step S _23, step S
_{If the} AC power source is not connected at ₂₈ , the electromagnetic switch is immediately turned off to step S ₂₄ , and the procedure is ended. In this way, the charging coefficient determined according to the progress of charging and the charging time is cumulatively added, and when the charging coefficient reaches a predetermined value, uniform charging is performed. You can Further, in this example, when the charging is stopped in the middle of the even charging, the cumulative value of the charging coefficient is reduced and reduced, and the subsequent charging mode is determined for this value, and Cumulative addition of charge coefficients is performed. From this point as well, it is possible to correctly determine the timing of the mode for uniform charging.

In the above description, the boundary between the charging stages 1 and 2 is set to be a half of the discharge amount at the inflection point.
V ₁ may be set to a value corresponding to a voltage having an appropriate value within the range of / 3 to 2/3. Similarly, although the charging stages 3 and 4 are separated in exactly half the time in the final charging, the charging stages 3 and 4 may be separated in an appropriate time within the range of 1/3 to 2/3 in the final charging. If the battery is stopped halfway during equal charging, the cumulative charging coefficient K
However, this value may be reduced to an appropriate value within the range of about 1/3 to 2/3. Furthermore, in the above, the charging process was divided into four stages, but at least 3
It may be divided into one stage, that is, a stage before and after the inflection point, and the number of stages may be three or five or more.

In the above description, the charging coefficient is determined not only in the charging step but also in the charging time, but the charging coefficient may be determined only in the charging step. Further, as described above, the state of charge is displayed on the display device 27 by the display elements L _{1 to} L ₆ , and
_{When 4} lights up, it indicates that the inflection point has been reached, and since the charging state is displayed in that way, the charging stage may be determined according to the display state of this display element, that is, for example, Until the display element L ₃ lights up, the charging stage is 1 and L
_{Before 3} lights L ₄ is lighted is the charge phase 2, the up L ₅ L ₄ is lighted is lighted and charge phase 3 may be the after which L ₅ lit so that the charge phase 4 . Further, in the above description, the normal charge or the equal charge is automatically executed depending on whether the cumulative value K of the charge coefficient is equal to or more than a predetermined value. If the value K is smaller than N, it is judged as normal charging and displayed on the display, and if it is larger, it is displayed as equal charging, and the user looks at the display and charges in the normal charging mode or the uniform charging mode. You may operate it. Further, the present invention lowers the voltage with a transformer having a leakage magnetic path,
Not only the so-called semi-regular charging method, but also other charging methods such as a constant current and constant voltage charging method can be applied.

[0021]

As described above, according to the present invention, the charging coefficient is determined according to the progress of charging and the state at the end of charging, and the cumulative value is used to determine whether to perform uniform charging. Therefore, it is possible to correctly determine whether to perform the uniform charge or the normal charge, prolong the life of the storage battery, and sufficiently draw out the electric capacity.

[Brief description of drawings]

FIG. 1 is a block diagram showing a general configuration of a charging device.

FIG. 2A is a diagram showing an example of a charging characteristic and divided charging stages, and FIG. 2B is a diagram showing a charging coefficient corresponding to a charging stage and charging time.

FIG. 3 is a flowchart showing an embodiment of the present invention.

Front Page Continuation (72) Inventor Masaaki Utsunomiya 110 Yokokura Nitta, Oyama City, Tochigi Prefecture Komatsu Fork Lift Co., Ltd.

Claims (4)

[Claims] 1. The charging process from the discharge end state to full charge is divided into a plurality of stages, corresponding to each charging stage, a larger charging coefficient is set in advance toward the end stage, and at the end of charging, The charging coefficient corresponding to the charging stage is cumulatively added, and if the cumulative addition value is less than or equal to a predetermined value, it is determined to be normal charging, and if it is more than a predetermined value, it is determined to be equal charging, and if it is determined to be equal charging, the cumulative addition value is reset. A charging method characterized by the above. 2. The charging method according to claim 1, wherein the charging coefficient is set to be larger as the charging step ends and set to be larger as the charging time is longer. 3. When the charging is completed during the uniform charging,
The charging method according to claim 1, wherein the cumulative addition value is reduced. 4. The charging method according to claim 1, wherein charging is automatically performed according to the determination result.