JP3956917B2 - Battery charger - Google Patents

Description

  The present invention relates to a battery charging device, and more particularly to a battery charging device for battery-powered electric vehicles.

  Conventionally, a battery charging device for charging a battery mounted on an industrial electric vehicle such as an electric forklift has a quasi-constant voltage charging method configured by a rectifier circuit of a transformer and a diode bridge without controlling a charging current. However, in the case of a battery charger that controls the charging current, a normal charging mode in which a relatively low current is supplied to the battery for charging and a charging current that is larger than the normal charging mode are supplied to the battery. Some are configured to be able to select any one of the quick charge modes in which the quick charge is performed in a short time after being supplied. In the normal charging mode, charging is performed with a relatively small charging current, so that charging can be performed while suppressing a rapid rise in the battery temperature or the like, but the charging time until the battery is fully charged becomes longer. On the other hand, the quick charge mode is selected, for example, when the battery discharge amount when using a forklift or the like during work hours is replenished during a break time. In this quick charge mode, it is larger than the normal charge mode. By supplying the charging current to the battery, the battery can be charged in a short time.

  If such a battery charging device is used, for example, after the end of the day, the battery is fully charged until the next morning in the normal charging mode, while the battery is charged in the quick charging mode during breaks such as lunch breaks. Can be quickly charged to compensate for the amount of discharge in the previous work.

  By the way, many of the battery charging devices described above are charged by a constant current / constant voltage method as shown in FIG. In this constant current / constant voltage method, a relatively large constant charging current is supplied to the battery in the initial stage of charging, and when the battery voltage reaches a predetermined voltage (for example, a battery inversion voltage), By maintaining the battery voltage at the predetermined voltage, the charging current is gradually reduced for charging. In addition, as shown in FIG. 9 in the embodiment, a two-stage constant current / constant voltage method capable of suppressing the charging current immediately before the completion of charging is also employed.

  However, in the quick charge mode, the charging current is larger than that in the normal charging mode, and a considerably large charging current is supplied to the battery in the initial stage of charging. Therefore, depending on the battery condition, the battery liquid temperature and battery charging There is a risk that the temperature of the transformer, the rectifying unit, and the like in the apparatus will rise excessively. Therefore, in the quick charge mode, when charging with a constant charging current from the start of charging, even when the battery voltage has not reached a predetermined voltage such as a reversal point voltage, when a predetermined time has elapsed since the start of charging. Also proposed is a configuration in which the charging current is reduced by switching from the quick charging mode to the normal charging mode (see, for example, Patent Document 1).

JP 2002-191136 A (page 5-7, FIG. 2, FIG. 4)

  However, when performing quick charging with the constant current / constant voltage method or the two-stage constant current / constant voltage method described above, a large charging current is supplied to the battery from the start of charging until a predetermined voltage is reached, The temperature of the battery or the battery charger increases. Furthermore, constant voltage charging is performed after the battery voltage reaches a predetermined voltage, so depending on conditions such as charging current and charging time, the electrode plate may deteriorate due to an increase in battery liquid temperature, resulting in battery life. May decrease. Also, in order to prevent the temperature of the transformer, rectifier, etc. in the battery charging device from rising excessively, it is necessary to dissipate the generated heat more effectively, and the structure of the battery charging device becomes complicated. Or it will enlarge.

  Further, in the battery charging device described in Patent Document 1, in the quick charge mode, after charging with a large current for a predetermined time after the start of charging, the battery is subsequently charged in the normal charge mode. Depending on the conditions, the temperature of the battery or the battery charger may be excessively increased.

  An object of the present invention is to provide a battery charging device capable of preventing the liquid temperature of a battery, the temperature of a transformer, a rectifying unit, and the like from excessively rising even in a quick charging mode.

Means for Solving the Problems and Effects of the Invention

According to a first aspect of the present invention, there is provided a battery charging apparatus connected to an external power source, wherein the battery is charged in any one of a normal charging mode and a quick charging mode in which the battery is rapidly charged with a charging current larger than the normal charging mode. A charging mode changing means for changing the charging mode to a standby mode in which charging is stopped when a predetermined quick charging time has elapsed since the start of charging in the quick charging mode . The charging mode changing means changes the charging mode from the standby mode to the normal charging mode when the standby mode continues for a predetermined standby time and when the standby mode is continuously connected to the external power source. It is characterized by this.

In this battery charger, either the normal charge mode or the quick charge mode can be selected. In the quick charge mode, a larger charge current than that in the normal charge mode is supplied to the battery so that the battery can be quickly turned on in a short time. Can be charged. However, if a large current is supplied to the battery for a long time in the quick charge mode, the temperature of the battery and the battery charger is excessively increased, leading to a reduction in the battery life. Therefore, when a predetermined rapid charging time has elapsed since the start of charging, the charging mode changing means changes the charging mode from the rapid charging mode to the standby mode, and sets the charging current of the battery to zero . Therefore, the battery and the battery charging device whose temperature has risen during a predetermined quick charging time in which a large charging current is supplied are cooled during the standby mode, and the temperature of the battery and the battery charging device is excessively increased. It can be prevented from rising.
In addition, after the quick charging is continued for a predetermined quick charging time, the charging mode is changed to the standby mode, and after the predetermined standby time has elapsed and the battery and the battery charging device are sufficiently cooled, the charging mode is changed to the standby mode. Therefore, when the quick charging mode is selected, the battery and the battery charging device can be fully charged while preventing the temperature of the battery and the battery charging device from excessively rising.
Furthermore, for example, when it is necessary to fully charge the battery by normal charging for a long time, and the quick charge mode is selected by mistake, if the standby mode is continued after the quick charge for a predetermined time, The battery may be undercharged. Therefore, when the battery charging device is continuously connected to the external power source during the standby mode, it is determined that it is necessary to charge the battery further, and the charging mode changing means performs the charging mode after a predetermined standby time has elapsed. Is changed from the standby mode to the normal charging mode, the battery can be fully charged even if the quick charging mode is selected by mistake.

According to a second aspect of the present invention, there is provided the battery charging device according to the first aspect , wherein the charging mode changing means changes the charging mode to the standby mode only when the battery voltage does not reach a predetermined voltage value during rapid charging. It is characterized by doing. Therefore, the battery voltage does not reach a predetermined voltage value such as a reversal point voltage even after a predetermined quick charging time has elapsed, and charging is performed only in a situation where the battery is continuously charged with a large charging current. By changing the mode to the standby mode, the charging time can be prevented from being unnecessarily changed by changing the charging mode to the standby mode.

  Embodiments of the present invention will be described. This embodiment is an example in which the present invention is applied to a battery charging device that charges a battery of an electric forklift.

First, the battery charger 1 will be briefly described with reference to FIG.
As shown in FIG. 1, in the battery charging device 1, a thyristor, a transistor, or the like is connected to a three-phase AC power source 2 that is an external power source via a power plug 3, an electromagnetic switch 4 that performs on / off control, and a transformer 5. The rectifying unit 6 constituted by is connected. Then, both end electrodes of the battery 7 are connected to the rectifying unit 6, and the battery 7 is charged by the output from the rectifying unit 6.

  The battery voltage V of the battery 7 is detected by a voltage detection unit 8 connected to both end electrodes of the battery 7, while the charging current I supplied to the battery 7 is detected by a current sensor 9. In the battery charging device 1, the controller 10 controls the rectification unit 6 based on detection signals from the voltage detection unit 8 and the current sensor 9 to appropriately connect the three-phase AC power supply 2 and the battery 7. By cutting / disconnecting, the battery voltage V and the charging current I are controlled to charge the battery 7. Furthermore, as will be described later, the battery charging device 1 supplies a relatively low charging current to the battery 7 to perform normal charging for a long time (for example, 8 hours or more), and more than the normal charging mode. It is configured to be able to charge the battery 7 by selecting one of the two charging modes, which is a quick charging mode in which a large charging current is supplied to the battery 7 and quick charging is performed in a short time (for example, about 1 hour). ing.

  The controller 10 includes a microcomputer including a CPU, a ROM, a RAM, and the like. The ROM controls the battery voltage V and the charging current I to charge the battery 7 as will be described later (FIG. 2). 4) and various set value data such as a later-described reversal point voltage V1, current values I1, I2, Ic and set times T1, T2 used in the battery charging process are stored. Further, as shown in FIG. 1, the controller 10 is connected to a normal charge switch 11 for selecting a normal charge mode and a quick charge switch 12 for selecting a quick charge mode. When any one of the charging switches 12 is operated, charging of the battery 7 is started in a charging mode corresponding to the operated switch.

  Therefore, for example, after the end of the day when the use of the forklift is finished, the power plug 3 is connected to the three-phase AC power source 2 and then the normal charging switch 11 is operated, and the battery 7 is completely discharged until the next morning in the normal charging mode. On the other hand, during the break time such as lunch break, it is possible to operate the quick charge switch 12 to rapidly charge the battery 7 in the quick charge mode to compensate for the discharge amount in the previous work. .

Next, battery charging processing by the battery charging device 1 of the present embodiment will be described with reference to the flowcharts of FIGS. 2 to 4 and FIGS. 5 to 7. In the following description, Si (i = 10, 11, 12,...) Indicates each step.
As shown in FIG. 2, when the normal charging switch 11 is operated (S11: Yes) while the power plug 3 is connected to the three-phase AC power source 2 (S10: Yes), the normal charging process of S14 is performed. And the battery 7 is charged in the normal charging mode. In the normal charging process, the battery 7 is charged by a constant current / constant voltage method as shown in FIG. This constant current / constant voltage method is a general charging method and will be described briefly.

  As shown in FIGS. 3 and 5, in this normal charging process, the battery 7 is charged with a constant charging current I1 in the initial stage of charging (S20, S21). As this constant current charging proceeds, as shown in FIGS. When the battery voltage rises and the battery voltage V detected by the voltage detector 8 reaches the reversal point voltage V1 (S20: No), switching to constant voltage charging (S22), the battery voltage V is changed to the reversal point voltage V1. The battery 7 is charged in the maintained state. When the constant voltage charging advances and the time from the start of constant voltage charging reaches a preset charging end time T3 (S23: Yes), the process returns to the main routine of FIG. 2 to end the charging.

  On the other hand, in FIG. 2, when the quick charge switch 12 is operated (S12: Yes), the quick charge process of S13 is executed, and the battery 7 is rapidly charged with a charge current larger than that in the normal charge mode. As shown in FIG. 4, in this quick charging process, first, the charging time timer T is started (S30), and then a constant charging current I2 larger than the charging current I1 in the normal charging mode is supplied to the battery 7. Then, constant current charging is performed (S31).

  Here, as shown in FIG. 6, when the battery voltage V detected by the voltage detection unit 8 reaches the inversion point voltage V1 (S32: No), the constant voltage charging is performed in the same manner as the normal charging process described above. Switching (S33), the battery 7 is charged with the battery voltage V maintained at the reversal point voltage V1, the constant voltage charging proceeds, and the time from the start of constant voltage charging has reached a preset charging end time T3. Sometimes (S34: Yes), the process returns to the main routine of FIG.

  On the other hand, in a state where the battery voltage V has not reached the reversal point voltage V1 (S32: Yes), the elapsed time T from the start of charging becomes longer than a predetermined quick charging time T1 (for example, T1 is about 1 hour). Sometimes (S35: Yes), as shown in FIG. 7, the charging is temporarily stopped and switched to the standby mode in which the charging current is 0 (S36). As described above, the charging is temporarily stopped before the battery voltage V reaches the inversion point voltage V1 by supplying a large charging current I2 to the battery 7 for a long time in the rapid charging mode. In order to prevent the temperature of the transformer 5 and the rectifying unit 6 in the battery charging device 1 from excessively rising, and to cool the battery 7 and the battery charging device 1 whose temperature has increased due to rapid charging during the standby mode. is there. Further, charging is unnecessarily performed by changing the charging mode to the standby mode only when the battery voltage V has not reached the reversal point voltage V1 and the battery 7 is continuously charged with a large charging current. By changing the mode to the standby mode, it is possible to prevent a long charging time.

In the standby mode, when the power plug 3 is intentionally pulled out by the operator to use the forklift (S37: No), the process returns to the main routine of FIG. However, with the power plug 3 continuously connected, the elapsed time T from the start of charging becomes longer than T2 (eg, T2 is about several hours) (S38: Yes), and the standby mode is a predetermined standby. When the time (T2-T1) continues, it is assumed that the battery 7 and the battery charger 1 are sufficiently cooled, and the routine returns to the main routine of FIG. 2, and then the normal charging process of FIG. 3 is started. That is, as shown in FIG. 3 and FIG. 7, from time T2, a constant charging current I1 is supplied to the battery 7 for constant current charging (S20, S21), and the battery voltage V reaches the inversion point voltage V1. Sometimes (S20: No), switching to constant voltage charging (S22), the battery 7 is charged with the battery voltage V maintained at the reversal point voltage V1. When the time from the start of constant voltage charging has reached a preset charging end time T3 (S23: Yes), the process returns to the main routine of FIG. 2 to end the charging.
In the above description, the microcomputer in the controller and S35 to S38 in FIG. 4 correspond to the charging mode changing means.

According to the battery charging device 1 described above, the following effects can be obtained.
1) When the quick charge mode is selected, when a predetermined quick charge time T1 has elapsed since the start of the charge, the charge is temporarily stopped, and the charge mode is changed from the quick charge mode to the standby mode where the charge current is 0. Are switched (S35, S36). Therefore, a large charging current I2 is not supplied to the battery 7 for a long time, and the battery 7 and the battery charging device 1 whose temperature rises during the rapid charging are reliably cooled during the standby mode in which the charging is stopped. As a result, the temperature of the battery 7 and the battery charger 1 can be prevented from rising excessively.

  2) When the above-mentioned standby mode continues for a predetermined standby time (T2-T1), the charging mode is changed from the standby mode to the normal charging mode (S38). Therefore, since the battery 7 and the battery charging device 1 are sufficiently cooled during the standby time and then the battery 7 is charged in the normal charging mode, the battery 7 and the battery charging device 1 are selected even when the quick charging mode is selected. The battery 7 can be fully charged while preventing the temperature of the battery from rising excessively.

  Further, the change of the charging mode from the standby mode to the normal charging mode is performed when the battery charging device 1 is continuously connected to the external power source during the standby mode (S37). Therefore, for example, when it is necessary to fully charge the battery 7 by normal charging for a long time, even if the operator accidentally operates the quick charge switch 12, the quick charge during the time T1 is performed. Since the normal charging is started after the charging stop state continues for the time of (T2-T1), the battery 7 is completely charged, and there is no shortage of charging.

Next, modified embodiments obtained by adding various modifications to the embodiment will be described.
1] In the above-described embodiment, when the quick charge mode is selected, the charge mode is changed to the standby mode by completely stopping the charge once the predetermined quick charge time T1 has elapsed. However, it is not always necessary to completely stop charging in the standby mode. That is, as shown in FIG. 8, the charging current I supplied to the battery 7 in the standby mode is set to a current I3 that is smaller than the charging current I1 in the normal charging mode. 1 can be cooled sufficiently. However, in this case, it is preferable to make the standby time (T2-T1) longer than in the above embodiment.

2] The threshold value of the battery voltage V at the time of switching from constant current charging to constant voltage charging does not necessarily need to be the inversion point voltage V1, and may be a value lower than V1.
3] The present invention can also be applied to a battery charging apparatus that employs a so-called two-stage constant current / constant voltage system capable of suppressing the charging current at the end of charging as shown in FIG.
4] The present invention can also be applied to a battery charger for battery-powered electric vehicles other than forklifts.

1 is a schematic circuit diagram of a battery charging device according to an embodiment of the present invention. It is a flowchart of the main routine of a battery charge process. It is a flowchart of a normal charging process. It is a flowchart of a quick charge process. It is explanatory drawing explaining the time change of the battery voltage and charging current in the normal charging mode of a constant current / constant voltage system. It is explanatory drawing explaining the time change of a battery voltage and a charging current in case a battery voltage reaches | attains a inversion point voltage during quick charge. It is explanatory drawing explaining the time change of a battery voltage and charging current when a battery voltage does not reach | attain inversion point voltage during quick charge. FIG. 8 is a diagram corresponding to FIG. It is explanatory drawing explaining the time change of the battery voltage and charging current in the normal charging mode of the two-stage constant current / constant voltage method of the modified form.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery charger 2 Three-phase alternating current power supply 3 Power plug 7 Battery 10 Controller

Claims (2)

In a battery charging apparatus that is connected to an external power source and can charge the battery in any one of the normal charging mode and the quick charging mode in which the battery is rapidly charged with a charging current larger than the normal charging mode.
Charging mode changing means for changing the charging mode to a standby mode for stopping charging when a predetermined quick charging time has elapsed since charging in the quick charging mode has started ;
The charging mode changing means changes the charging mode from the standby mode to the normal charging mode when the standby mode continues for a predetermined standby time and when the standby mode is continuously connected to the external power source. A battery charger characterized by that. 2. The battery charging device according to claim 1, wherein the charging mode changing unit changes the charging mode to a standby mode only when the battery voltage does not reach a predetermined voltage value during quick charging.

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