JP2009254055A - Charger device and charging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging device and a charging method which can charge a storage battery to an appropriate capacity by simple operation or time management even for complicated control by reducing measurement error of a detection voltage which is used for stopping charge control. <P>SOLUTION: Since constant current charging is performed with a small current value having less impedance impact as a final charging current, a detection voltage used for stopping charge control hardly causes an error. A timer is used only for final constant current control, and complicated processing is not required. Since time management is required only for final constant current control, software control is simplified and the CPU memory capacity required is reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device and a charging method including a charging circuit that performs charging by converting alternating current into direct-current power and supplying the same to a storage battery used in a vehicle such as a forklift.

The conventional charging device has a problem that the larger the size, the longer it takes to charge and the lower the charging efficiency. For this reason, various controls for charging the storage battery in a short time have been devised.
As one of the controls, there is one in which the control is performed through a plurality of different controls which are performed by changing the current value stepwise every time the specified voltage is reached after starting the charge control. In this control, the cumulative time every time the specified voltage is reached is calculated, and then charging is performed by changing the charging current stepwise. Based on the cumulative time, the time to stop charging is calculated, and the storage battery is There is a charging control device configured to stop charging (for example, Patent Document 1).
Japanese Patent No. 2513339 (FIG. 2 (b))

In these inventions, as shown in FIG. 5, the charging voltage is measured, and the time T1 to be cut off is calculated based on the time To from the initial charging stage when the voltage Vo is reached. In this initial stage To, the initial charging current is charged with a large current, so the impedance of the inside of the storage battery and the wiring is easily affected by the temperature due to changes in the temperature, and particularly requires a large current at constant current or constant power. During rapid charging, an error may increase in detecting a voltage that reaches a predetermined voltage Vo (inflection point).
For this reason, as shown in FIG. 5, when the calculation is based on the initial time and charging is finished, the value of T1 calculated from the value obtained by measuring the time to reach the inflection point is unlikely to be an appropriate value. There was a problem of overcharging or undercharging.

Also, considering the life of the storage battery and charging efficiency, after passing through these different control means of current → constant voltage → constant current, constant current → constant current → constant current, constant power → constant current → constant current When charging with a constant current is completed, it is also possible to measure the time each time the control is switched, and to control the charging based on the accumulated value. There is an error in the measured time due to the effects of noise and impedance described above. However, the error is further increased due to the accumulation of errors, and when charging is completed based on the accumulated value, there is a problem that overcharge or undercharge occurs.
In addition, when charging with a constant current is terminated after passing through a plurality of different control means described above, there are a large number of timers for measuring the time from the initial stage, or the data to be processed based on the timers. The program to be designed is complicated because of complicated management.

  Therefore, an object of the present invention is to reduce a measurement error of a reference value used for stopping charging control, and charge a storage battery to an appropriate capacity by simple calculation or time management even in complicated control. It is an object to provide a charging device and a charging method that can be used.

  In order to solve this problem, the present invention as claimed in claim 1 includes a charge control means (10) for supplying DC power to the storage battery (20) for charging, and a voltage detection means (17) for detecting the voltage of the storage battery. ) And a current detection means (13) for detecting a charging current, wherein the charging control means includes a plurality of different control means (constant current → constant voltage → constant current, constant current, After performing current → constant current → constant current and constant power → constant current → constant current, initial constant current control or initial constant power control (S7 or intermediate constant current control), It has a final constant current charging means (final constant current control) that performs control with a final charging current (If) that has a constant current value with little influence, and the final constant current charging means starts the final constant current charging means. Then, timer means for measuring time (t) In response to the detection value (detection voltage, detection temperature) for detecting the state of the storage battery during charging by the timer A) and the final constant current charging means has reached a reference value (reference voltage or reference temperature), Calculation means (18 · S19) for calculating the time (Ta) for stopping charging based on the time measured by the timer means, and the final determination after the time (Ta) obtained based on the calculation means. Charge stopping means (S25 / S27) for stopping the charging of the current charging means.

  With the above configuration, by performing constant current charging with a small current value with little influence of impedance as the final charging current, detection errors used to stop charging control are less likely to occur. Only in the final constant current charging means, a timer may be used and complicated processing is not required. Therefore, it is sufficient to manage the time only in the final constant current charging means, and the time management becomes easy. Further, no cumulative error occurs.

  In order to solve this problem, the present invention according to claim 2 is a charging method for charging by supplying DC power to the storage battery (20), and a plurality of different controls (constant current → constant voltage → constant current, Constant current → constant current → constant current or constant power → constant current → constant current, constant voltage control via initial constant current control or initial constant power control (S7 or intermediate constant current control) and impedance Starting constant current charging with a final charging current (If) that is less affected by the current, and measuring a time (t) after starting constant current charging with the final charging current with a timer means (timer A); The time measured by the timer means in response to the detection value (detection voltage, detection temperature) detecting the state of the storage battery during the charging with the final charging current reaching the reference value (reference voltage or reference temperature) When charging is stopped based on (t) (Ta) is calculated (S19), and the constant current charging with the final charging current is stopped after the lapse of the time (Ta) obtained by the calculation (S25 / S27). .

  By performing the constant current charging with a small current value with little influence of impedance as the final charging current by the above method, a detection error used to stop the charging control is less likely to occur. Only in the final process, a timer may be used and complicated processing is not required. Therefore, it is sufficient to manage time only in the final process, and time management becomes easy. Further, no cumulative error occurs.

  In order to solve this problem, the present invention as claimed in claim 3 comprises a charge control means (10) for charging by supplying DC power to the storage battery (20), and a voltage detection means (17) for detecting the voltage of the storage battery. ) And a current detection means (13) for detecting a charging current, wherein the charging control means starts an initial constant current with an initial charging current (Ii). The charging in the initial constant current charging means is terminated in response to the voltage detected in the battery voltage during the charging in the charging means and the initial constant current charging means reaching the set voltage (Vo). Constant voltage charging means (constant voltage control) that starts constant voltage charging at (Vo or Vlo), and a switching current (charge current during charging in the constant voltage charging means is smaller than the first initial charging current) Ih), the constant voltage charging Final constant current charging means (final constant current control) for starting constant current charging at a final charging current (If) that is smaller than the switching current and less affected by impedance, and ends the charging at the stage, and the final constant current Timer means (timer A) for measuring the time after starting the charging means, and the timer means in response to the storage battery reaching a reference voltage (Vh) during charging by the final constant current charging means The calculation means (18 · S19) for calculating the time (Ta) for stopping charging based on the time (t) measured in step (b), and the final constant current charging after the time (Ta) obtained by the calculation means has elapsed. Charge stopping means (S25 / S27) for stopping charging of the means.

  With the above configuration, by performing constant current charging with a small current value with little influence of impedance as the final charging current, an error in detection voltage used to stop charging control is less likely to occur. Only in the final constant current charging means, a timer may be used and complicated processing is not required. Therefore, it is only necessary to manage the time only in the final constant current charging means, and the time management becomes easy. Further, no cumulative error occurs.

  In order to solve this problem, the present invention according to claim 4 is a charging method for charging by supplying DC power to the storage battery (20), and starting constant current charging with an initial charging current (Ii). (Initial constant current control S3) and the charging at the initial charging current is terminated in response to the voltage of the storage battery reaching a set voltage (Vo) during charging at the initial charging current, and the setting Step of starting constant voltage charging with voltage (S5, S7), and charging at the set voltage in response to a charging current having reached a switching current smaller than the initial charging current during charging at the constant voltage charging The constant current charging is started with a final charging current that is smaller than the switching current and less affected by the impedance, and the time (t) after the constant current charging is started with the final charging current is determined by timer means (timer A ) In step (S9) S15), and charging is stopped based on the time (t) measured by the timer means in response to the voltage detected by the storage battery reaching the reference voltage (Vh) during charging at the final charging current. A time (Ta) to be calculated (S19), and the constant current charging at the final charging current is stopped after the time (Ta) obtained by the calculation has elapsed (S25 and S27). And

  With the above method, constant current charging is performed with a small current value with little influence of impedance as the final charging current, so that an error in detection voltage used to stop the charging control is less likely to occur. Only in the final process, a timer may be used and complicated processing is not required. Therefore, it is sufficient to manage time only in the final process, and time management becomes easy. Further, no cumulative error occurs.

  According to the charging device and the charging method of the present invention, it is possible to reduce the measurement error of the detection voltage used for stopping the charging control and to charge the storage battery to an appropriate capacity.

The best mode for carrying out the present invention will be described below with reference to FIG. FIG. 1 is a functional block diagram of a charging device 1 according to an embodiment of the present invention.
The charging device 1 shown in FIG. 1 is input to the full-wave rectification unit 3 using a commercial AC power source 2 as a power source. The DC conversion unit 5 connected to the full-wave rectification unit 3 supplies the DC power converted from AC to DC to the storage battery 20 via the current detection unit 13. The storage battery 20 is a clad lead storage battery, and the battery voltage is DC48V.

  The DC conversion unit 5 includes an inverter 7, a transformer 9, and a rectification unit 11. The inverter 7 converts the electric power converted into direct current by the full-wave rectification unit 3 into electric power obtained by stepping down the voltage via the transformer 9 and is controlled by the inverter control unit 15.

  The current detection unit 13 measures the charging current output from the DC conversion unit 5 and gives the measured value to the charging control unit 10. The charging control unit 10 controls the current output from the direct current conversion unit 5 from the obtained value through the inverter control unit 15 so as to have a predetermined current value.

Moreover, the voltage detection part 17 measures the voltage of the terminal of the storage battery 20, and gives the measured value to the charge control part 10. The charging control unit 10 performs control so that the charging voltage output from the DC conversion unit 5 becomes a constant voltage value through the inverter control unit 15 from the obtained value. The charging control unit 10 includes a CPU 19 with built-in EEPROM / RAM,
A charge control processing program, a timer A / timer B used for the charge control processing, and an arithmetic means 18 for performing arithmetic processing based on a preliminarily stored data value and a value measured by the timer A are provided. ing.

  Operation | movement of the charging device 1 in Example 1 is demonstrated based on FIG.2 and FIG.3. FIG. 2 is a diagram illustrating the relationship between the battery voltage, the charging current, and the time of the charging device according to the first embodiment. FIG. 3 is a flowchart showing the operation of the charging device in the embodiment of the present invention.

  When charging is started (S1), initial constant current control as initial constant current means is performed so as to charge the storage battery 20 with an initial charging current Ii that is a constant constant current (S3). The value of the initial charging current Ii at this time is 60 A, for example. In this initial constant current control, based on the value detected by the current detection unit 13, the charge control unit 10 maintains the output charging current to be a constant initial charging current Ii, and charges the storage battery 20. ing. During the initial constant current control, the voltage of the storage battery 20 rises.

  Then, when the voltage of the storage battery 20 measured by the voltage detector 17 reaches the set voltage Vo (S5), switching to constant voltage control as constant voltage charging means is performed (S7). In this constant voltage control, based on the value detected by the voltage detector 17, the charge controller 10 maintains the output charging voltage to be a constant voltage (set voltage Vo), and charges the storage battery 20 Yes. During this constant voltage control, the charging current of the storage battery 20 drops.

  When the lowered charging current reaches the predetermined switching current Ih (S9), the timer A as the timer means operates (S11), and the time (t) is measured by the timer A (S13). The value of the switching current Ih at this time is, for example, 30A. At the same time, final constant current control as final constant current charging means is performed (S15). In this final constant current control, based on the value detected by the current detection unit 13, the charge control unit 10 makes the output charging current smaller than the switching current Ih and has a small impedance, for example, a constant value of 15A. The storage battery 20 is charged while maintaining the final charging current If. During this final constant current control, the voltage of the storage battery 20 rises.

When the voltage reaches the inflection point voltage Vh (S17), an arithmetic process is performed (S19). In this calculation process, the time of Ta is calculated based on the measured value of time (t). Then, after setting the value of Ta, the timer B is activated (S21), and the timer B measures the time (Ta) (S23). Further, the final constant current control is maintained as it is (S24).
Next, when the timer B reaches the set value Ta (S25), the charging is stopped and the charging control is ended (S27).
The storage battery 20 is charged to an appropriate value by the above control.

The operation of the charging device 1 in the second embodiment will be described with reference to FIG. FIG. 4 is a diagram illustrating the relationship between the battery voltage, the charging current, and the time of the charging device in the multistage constant current charging control according to the second embodiment.
When charging is started, the initial constant current control is performed so that the storage battery 20 is charged with the initial charging current Ii that is a constant constant current. The value of the initial charging current Ii at this time is 60 A, for example. In this initial constant current control, based on the value detected by the current detection unit 13, the charge control unit 10 maintains the output charging current to be a constant initial charging current Ii, and charges the storage battery 20. ing. During the initial constant current control, the charging voltage of the storage battery 20 increases.

Then, when the voltage of the storage battery 20 measured by the voltage detector 17 reaches the inflection point voltage Vh, the control is switched to the intermediate constant current control. The value of the intermediate charging current Is at this time is, for example, 30A. Even during the intermediate constant current control, the charging voltage of the storage battery 20 increases. Then, when the voltage of the storage battery 20 measured by the voltage detection unit 17 reaches the inflection point voltage Vh again, it is switched to the final constant current control.
When switched to the final constant current control, the timer A is activated and the time (t) is measured by the timer A. In this final constant current control, the charging control unit 10 maintains the output charging current to be a constant final charging current If of a value of 15 A, for example, which is smaller than the intermediate charging current Is and has little influence of impedance, The storage battery 20 is charged. During the final constant current control, the charging voltage of the storage battery 20 increases.

And when the voltage of the storage battery 20 reaches the inflection point voltage Vh, a calculation process is performed. In this calculation process, the time Ta is calculated based on the measured value of the timer A. And after setting the value of Ta, the timer B operates and time is measured. The final constant current control is maintained as it is.
Next, when the timer B reaches the set value Ta, the charging is stopped and the charging control ends.
The storage battery 20 is charged to an appropriate value by the above control.
Note that the steps from the flowcharts S11 to S27 of the first embodiment are also used in the second embodiment as described above.
[Effect in this embodiment]

(1) In the present invention, by performing constant current charging with a small current value with little influence of impedance as the final charging current If, detection errors used for stopping the charging control are less likely to occur. Therefore, overcharge or undercharge does not occur.

(2) The present invention calculates the time for stopping the final charge control without using the time that is easily affected by the impedance of the initial charge as in the prior art, and the time for the control with less voltage value error. Since (t) is measured (S13) and the time (Ta) for stopping the control can be calculated from the measured value (S19), the storage battery 20 can be charged in an appropriate state. Therefore, overcharge or undercharge does not occur.

(3) The present invention only uses the time t only in the final constant current control (S11 to S27), and does not require complicated processing. Therefore, it is sufficient to manage the time only in the final constant current control, the time management is easy, the software control is simplified, and the storage capacity of the CPU can be reduced. Further, there is no cumulative error such that errors due to noise or the like and errors due to impedance accumulate.

(4) In particular, the larger the storage battery, such as a forklift, compared to the small storage battery of a mobile phone, the larger the current capacity value, the more easily affected by the impedance of the initial charging, and used for stopping charging control. However, according to the present invention, since the voltage is detected with a small current value that is not easily affected by the impedance, the measurement error of the detection voltage to be used is reduced, and the storage battery has an appropriate capacity. 20 can be charged.

(5) A storage battery impregnated with an electrolyte such as that used in a forklift or the like cannot reach full charge immediately because the electrolyte stays from exceeding the inflection point voltage Vh until it is fully charged. A certain time is required. Therefore, the time (t) in the control with a small voltage value error is measured (S13), and the time (Ta) for stopping the control can be calculated from the measured value (S19). And the storage battery 20 can be charged in an appropriate state, and insufficient charging does not occur.
(Other technical ideas considered from this embodiment)

A charging apparatus comprising: charge control means for supplying DC power to a storage battery for charging; voltage detection means for detecting the voltage of the storage battery; and current detection means for detecting a charging current.
The charging control means includes an initial constant current charging means for starting constant current charging at an initial charging current, and the initial constant current in response to the storage battery reaching a reference voltage during charging by the initial constant current charging means. An intermediate constant current charging means for ending charging at the charging means and starting constant current charging at an intermediate charging current that is smaller than the initial charging current;
In response to the storage battery reaching the reference voltage during charging in the intermediate constant current charging means, charging in the intermediate constant current charging means is terminated, and is smaller than the intermediate charging current and less affected by impedance. A final constant current charging means for starting constant current charging at the final charging current; a timer means for measuring a time after starting the final constant current charging means;
A computing means for computing a time to stop charging based on a time measured by the timer means in response to the storage battery reaching a reference voltage during charging by the final constant current charging means; and the computing means And charging stop means for stopping charging of the final constant current charging means after elapse of the time obtained by the charging device.

With the above configuration, by performing constant current charging with a small current value with little influence of impedance as the final charging current, an error in detection voltage used to stop charging control is less likely to occur. Only in the final constant current charging means, a timer may be used and complicated processing is not required. Therefore, it is only necessary to manage the time only in the final constant current charging means, and the time management becomes easy. Further, no cumulative error occurs.
(Examples of changes to other embodiments)

The example which changed embodiment described above into other embodiment is shown below.
The set voltage Vo as the reference value and the inflection point voltage Vh (reference voltage) as the reference value may take the same value, or the inflection point voltage Vh may be higher than the set voltage Vo.
In the constant voltage control, the value at which the initial charging current has reached the set voltage Vo and the voltage value at the time of control with the constant voltage do not necessarily have to be the same, and may be the lowered voltage value Vlo.
-Instead of the reference voltage, the detection value obtained by measuring the temperature of the battery or the ambient temperature in the charging device by means of temperature detection means such as a thermistor may be determined based on a preset reference temperature, and converted to a voltage value as the reference value Possible setting values are also possible.
-There is no particular limitation on the inverter type, and there are chopper type, full bridge type, etc.
Although two timers A and B and two timers have been described, a single timer may be used to measure time t and time T.
In multi-stage charging of constant current charging, not only three stages but also four stages or five stages may be used.

-Although the initial constant current control was demonstrated by control of constant current charge, initial constant power control control which performs charge by constant power which makes electric power constant may be sufficient.
Any control may be taken between the initial constant current control and the final constant current control, and a large number of the same control or different controls may be passed.
-Although the battery voltage was demonstrated with DC48V, DC80V may be sufficient.
-Initial charging current, switching current, intermediate charging current, and final charging current are not particularly limited.
In constant voltage control, making the voltage constant includes maintaining the optimum state by correcting while changing the voltage value due to temperature change.

It is a functional block diagram of the charging device in the embodiment of the present invention. It is a figure which shows the relationship between the battery voltage of the charging device in the constant current constant voltage control in Example 1, charging current, and time. FIG. 3 is a flowchart illustrating the operation of the charging device according to the first embodiment. It is a figure which shows the relationship between the battery voltage of the charging device in the multistep constant current charge control in Example 2, charging current, and time. It is a figure which shows the battery voltage of the charging device in a prior art example, and the relationship of time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Charging device, 2 ... AC power supply, 3 ... Full wave rectification part, 5 ... DC conversion part,
7 ... Inverter, 9 ... Transformer,
DESCRIPTION OF SYMBOLS 10 ... Charge control part, 11 ... Rectification part, 13 ... Current detection part (current detection means), 15 ... Inverter control part, 17 ... Voltage detection part (voltage detection means),
18 ... Calculation means, CPU ... 19,
20: Storage battery,
A ... Timer A (timer means), B ... Timer B (timer means),
Vo: set voltage, Vh: inflection point voltage (reference voltage),
Ii: initial charging current, Ih: switching current, Is: intermediate charging current,
If ... Final charge current.

Claims (4)

A charging apparatus comprising: charge control means for supplying DC power to a storage battery for charging; voltage detection means for detecting the voltage of the storage battery; and current detection means for detecting a charging current.
The charging control means comprises a final constant current charging means for performing control with a final charging current having a constant current value with less influence of impedance after performing a plurality of different control means,
The final constant current charging means includes a timer means for measuring time when the final constant current charging means is started, and a detection value obtained by detecting the state of the storage battery during charging by the final constant current charging means is a reference value. And a calculation means for calculating a time for stopping charging based on the time measured by the timer means, and the final constant current charging means after elapse of the time obtained based on the calculation means. And charging stop means for stopping the charging of the charging device. A charging method for charging by supplying DC power to a storage battery,
A step of performing a plurality of different controls, a step of starting constant current charging with a final charging current with little influence of impedance, and a step of measuring the time after starting constant current charging with the final charging current with a timer means;
In response to the detection value detecting the state of the storage battery during charging at the final charging current reaching a reference value, a time for stopping charging is calculated based on the time measured by the timer means, And a step of stopping constant current charging at the final charging current after elapse of time obtained by calculation. A charging apparatus comprising: charge control means for supplying DC power to a storage battery for charging; voltage detection means for detecting the voltage of the storage battery; and current detection means for detecting a charging current.
The charging control means includes an initial constant current charging means for starting constant current charging with an initial charging current, and the initial constant current in response to the storage battery reaching a set voltage during charging by the initial constant current charging means. A constant voltage charging means for ending charging at the charging means and starting constant voltage charging at a set voltage;
In response to the fact that the charging current has reached a switching current that is smaller than the first initial charging current during charging in the constant voltage charging means, the charging in the constant voltage charging means is terminated, and from the switching current A final constant current charging means for starting constant current charging with a small final charging current with little influence of impedance, a timer means for measuring the time since the final constant current charging means is started,
A calculating means for calculating a time to stop charging based on a time measured by the timer means in response to a voltage detected by the storage battery reaching a reference voltage during charging by the final constant current charging means; And a charging stop means for stopping the charging of the final constant current charging means after elapse of the time obtained by the calculating means. A charging method for charging by supplying DC power to a storage battery,
A step of starting constant current charging at an initial charging current;
Ending charging at the initial charging current in response to the voltage of the storage battery reaching a set voltage during charging at the initial charging current, and starting constant voltage charging at the set voltage;
During charging with the constant voltage charging, charging at the set voltage is terminated in response to the switching current reaching a switching current smaller than the initial charging current, and the final effect is smaller than the switching current and less affected by impedance. A step of starting constant current charging with a charging current and measuring a time after starting constant current charging with the final charging current with a timer means;
In response to the fact that the voltage detected by the storage battery during charging at the final charging current has reached a reference voltage, a time for stopping charging is calculated based on the time measured by the timer means, and obtained by the calculation. And a step of stopping constant current charging at the final charging current after a lapse of a given time.

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