JP2007151261A - Battery charge / discharge system - Google Patents

Abstract

A plurality of batteries connected in parallel and having characteristic variations are fully charged (full charge) and the charging period is shortened.
When a battery voltage or a battery current reaches a point of about 95% of a full charge state, for example, constant current pulse charging is performed from a multi-stage constant voltage charging system as shown by points c to g in the figure. By switching to the system and switching the batteries in time series and performing pulse charging, the individual batteries having characteristic variations are fully charged, and the charging time in the pulse charging region is shortened compared to the prior art.
[Selection] Figure 1

Description

  The present invention relates to a battery charge / discharge system suitable for supplying electric power to a power machine such as an electric vehicle or an electric propulsion ship using a storage battery as a primary power source and a system including a generator for charging the storage battery.

  In addition to the constant voltage charging method and the constant current charging method, the pulse charging method has been widely put into practical use for battery charging. However, it has been pointed out that if a pulse charging method is used in a large current charging area with a small amount of charge in a system using a large capacity battery, a powerful noise is generated, which causes serious malfunctions to the equipment and devices that make up the system. Yes. Therefore, the applicant has previously filed, for example, the one shown in Patent Document 1, assuming that charging is performed with a continuous voltage or current that does not generate noise in the large current charging region and the pulse charging method is performed in the small current charging region at the end of charging. is doing.

4 and 5 are explanatory diagrams showing the charging method disclosed in Patent Document 1. FIG.
FIG. 4 shows an example of constant current charging → constant current charging → constant voltage pulse charging. In this constant current charging operation in the previous stage, when the battery voltage reaches VBc, switching from constant current charging to constant voltage pulse charging is performed, and pulse charging is performed from point c to point d when charging is completed.
FIG. 5 shows an example of constant current charging → constant voltage charging → constant current pulse charging. In the preceding constant voltage charging operation, when the battery current reaches IBcΣ, switching from constant voltage charging to constant current pulse charging is performed, and pulse charging is performed from point c to point f when charging is completed.

JP-A-2005-080318

However, according to the method shown in FIGS. 4 and 5, the charge amount is considerably lower than the full charge (full charge) state at the point c when switching to pulse charge. There is a problem that the charging time to the points d and f becomes longer.
Accordingly, an object of the present invention is to shorten the charging time in the pulse charging operation region.

In order to solve such a problem, in the invention of claim 1, in a charge / discharge system that charges and discharges a plurality of batteries connected in parallel,
In the initial stage of the final charging area, charging is performed by changing the charging voltage or charging current step by step using the multi-stage constant voltage charging method or multi-stage constant current charging method, and the battery voltage or battery current is about 95% of the fully charged state. If the battery reaches full charge, it switches from the multi-stage constant voltage charging system or multi-stage constant current charging system to the constant voltage pulse charging system or constant current pulse charging system, and switches the battery in time series to perform pulse charging. It is characterized in that the charging is completed sequentially.

  According to the present invention, it is possible to significantly shorten the charging time in the pulse charging operation region as compared with the prior art while fully charging a plurality of batteries having characteristic variations.

FIG. 1 is an explanatory diagram for explaining an embodiment of the present invention, and FIG. 2 is an explanatory diagram for explaining another embodiment of the present invention.
That is, the present invention replaces the conventional constant voltage pulse or constant current pulse charging method shown in FIG. 4 or FIG. 5 with multi-stage constant voltage charging → constant voltage pulse charging method or multi-stage constant current charging as shown in FIG. → The constant current pulse charging method is implemented.

First, the operation of FIG. 1 will be described with reference to FIG.
FIG. 3 is a block diagram showing a charge / discharge system in which the present invention is implemented. 1-2 is a battery (B1-Bn), 3-4 are mechanical contact switches, 5-6 are semiconductor switches, 7-8. Is a diode, 9 to 10, 14, 19, and 23 (SH1 to SHn, SHB, and SHG) are current detectors, 11 to 13, and 21 (VD1 to VDn, VDB, and VDG) are voltage detectors, 15, 20, and 24 27, 29 to 31, 35 (SWB, SWGH, SWLH, SWMH, SWC to SWF, SWG) are switches, 16 is a generator (G), 17 is a generator field (Gf), and 22 is an auxiliary power system. (L), 25 is a propulsion motor (M), 28 is a battery charge / discharge & state monitoring control device, 32 is a voltage setting device, 33 is a current setting device, 34 is a generator control device, and 36 is a signal.

  That is, the charge / discharge system shown in FIG. 3 includes batteries 1 to 2 (B1 to Bn), a generator 16 (G), an auxiliary power system 22 (L), a propulsion motor 25 (M), and the like. Not only charges the batteries 1 and 2, but also supplies power to the auxiliary power system 22 and the propulsion motor 25. In addition, although the batteries 1 and 2 are shown here as single units, they actually have a configuration of a battery group in which a plurality of single cells are connected in series.

  In FIG. 1, when it is detected by the battery voltage detector 13 (VDB) of the battery charge / discharge & state monitoring control circuit 28 shown in FIG. 3 that the battery voltage VB has reached VBc in the constant current charging operation of the previous stage, the battery The charge / discharge & state monitoring control circuit 28 determines this, and switches the generator control from the constant current control to the constant voltage control, and a voltage set value command with VBc as the voltage set value via the signal 36. To device 34. The battery is charged at a constant voltage by the generator voltage controlled at a constant voltage by this command. The battery voltage condition for starting constant voltage charging, that is, the battery voltage VBc at the point c is set to a battery voltage value corresponding to a state of about 70% of the fully charged state, for example.

When the battery current detector 14 (SHB) detects that charging has progressed and the charging current IBΣ has reached IBdΣ, the battery charging / discharging & state monitoring control circuit 28 performs battery charging / discharging & state monitoring control according to the setting program. The voltage setting value VBd of the next step corresponding to the charging current value IBdΣ stored in the setting value table provided in the circuit 28 is set as the generator voltage setting value VBd, and this voltage setting value VBd is transmitted via the signal 36. Is supplied to the generator control device 34, and the battery is charged at a constant voltage by generator constant voltage control using VBd as a voltage set value.
When the charging current IBΣ reaches IBeΣ as the charging time elapses, the generator voltage is set to VBe, and when IBfΣ is reached, the generator voltage is increased sequentially like VBf... When the monitoring control circuit 28 determines, the constant voltage charging mode is switched to the constant voltage pulse charging mode.

The battery charge / discharge & state monitoring control circuit 28 gives a voltage command value VBg to the generator controller 34 via a signal 36, and is turned off to the mechanical contact switches 3 (SW1) to 4 (SWn) connected to the respective batteries. Constant voltage pulse charging is performed by giving an (OFF) command to the semiconductor switches 5 (Q1) to 6 (Qn) in an on-off (on-off) command in time series.
Here, assuming that the full charge voltage of the lithium battery is about 4.1 to 4.2 V, the generator charges the battery with the output voltage of the voltage command value VBg corresponding to 4.1 to 4.2 V, and the battery The battery charging / discharging & state monitoring control circuit 28 determines that the charging currents IB1 to IBn detected by the individual current detectors 9 (SH1) to 10 (SHn) provided in the circuit have reached a preset current value IBh. Then, the corresponding semiconductor switches 5 to 6 are sequentially turned off to complete the charging.
In this way, pulse charging is performed from the g point (about 95% of the full charge) in the final charge region close to the full charge state, and the battery with the characteristic variation is fully charged and the charging time is shortened. It aims to make it easier. Note that IBgΣ, which is the charging current condition at the point g, that is, the point at which constant voltage pulse charging is started, is preferably set to a charging current value corresponding to a state of 90 to 95% of the fully charged state, for example.

  In addition, instead of the multi-stage constant voltage charging → constant voltage pulse charging method described in FIG. 1, when it is detected that the battery voltage VB has reached VBc in a constant current charging operation using IBgΣ as a current setting value (point c) Then, a method of switching to a constant voltage charging operation in which VBf having a voltage level that is three steps higher than VBc is set as a voltage setting value, that is, one-stage constant voltage charging → constant voltage pulse charging, is also conceivable. In the constant voltage pulse charging method, the batteries 1 and 2 having the battery voltage VB of VBc at the point c are charged in a stepwise manner with a high charging voltage. May cause damage to the batteries 1 and 2, which is not preferable.

  On the other hand, in the multi-stage constant voltage charge-> constant voltage pulse charge system in which multi-stage constant voltage charging is performed in the manner of VBc → VBd → VBe → VBf as shown in FIG. Since the amount of increase is suppressed small, the charging current that flows transiently to the batteries 1 and 2 is also small, and damage to the batteries 1 and 2 can be prevented. And in the case of a lithium battery, since the internal resistance is smaller than that of a lead battery or the like, the charging current flowing transiently becomes larger due to a stepwise increase in the charging voltage, thereby increasing the level of damage to the battery. In a battery system using a lithium battery, it is particularly preferable to apply the multistage constant voltage charging → constant voltage pulse charging method as shown in FIG.

Next, the operation of FIG. 2 will be described with reference to FIG.
In this case, if the battery current detector 14 (SHB) of the battery charge / discharge & state monitoring control circuit 28 shown in FIG. 3 detects that the charging current IBΣ has reached IBcΣ in the constant voltage charging operation of the previous stage, the battery The charge / discharge & state monitoring control circuit 28 determines this, and a switching command for switching the generator control from constant voltage control to constant current control and a current setting value command with IBcΣ as a current setting value are sent via the signal 36 to the generator. This is given to the control device 34. The battery is subjected to constant current charging by the generator current that is constant current controlled by this command. The charging current condition for starting the constant current charging, that is, the charging current IBcΣ at the point c is set to a charging current value corresponding to, for example, about 70% of the fully charged state.

When the battery voltage detector 13 (VDB) detects that charging has progressed and the battery voltage VB has reached VBd, the battery charge / discharge & status monitoring control circuit 28 performs battery charge / discharge & status monitoring control according to the setting program. The current setting value IBdΣ of the next step corresponding to the battery voltage value VBd stored in the setting value table provided in the circuit 28 is set as the generator current setting value IBdΣ, and this current setting value IBdΣ is transmitted via the signal 36. Is supplied to the generator controller 34, and the battery is charged with constant current by generator constant current control with IBdΣ as a current set value.
When the battery voltage VB reaches VBe as the charging time elapses, the generator current is set to IBeΣ. When the battery voltage VB reaches VBf, the generator current is decreased sequentially like IBfΣ... When the monitoring control circuit 28 determines (this is point g in FIG. 2 and about 95% of full charge), the constant current charge mode is switched to the constant current pulse charge mode. Note that VBg, which is the battery voltage condition at the point g, that is, the point at which constant current pulse charging is started, is preferably set to a battery voltage value corresponding to a state of 90 to 95% of the fully charged state, for example.

The battery charge / discharge & state monitoring control circuit 28 gives a current command value IBg to the generator control device 34 via a signal 36, and is turned off to the mechanical contact switches 3 (SW1) to 4 (SWn) connected to each battery. The command is given to the semiconductor switches 5 (Q1) to 6 (Qn) by an ON-OFF command in time series to perform constant current pulse charging.
Here, assuming that the full charge voltage of the lithium battery is about 4.1 to 4.2 V, the voltage detected by the voltage detectors 11 (VD1) to 12 (VDn) provided in the individual battery circuits is 4. When the battery charge / discharge & state monitoring control circuit 28 determines that the voltage is 1 to 4.2 V (VBh), the corresponding semiconductor switches 5 to 6 are sequentially turned off to complete the charging.

In FIG. 1, the transition is made from the point g in the final charging region to the constant voltage pulse charging method, but the transition may be made to the constant current pulse charging method, and the constant charging is started from the point g in the final charging region in FIG. Of course, instead of the current pulse charging method, the constant voltage pulse charging method may be used.
By the way, in a large-capacity system using a storage battery as a primary power source, it is considered that there is a variation in characteristics of each unit cell, and a battery system in which a plurality of cell groups are connected in parallel by connecting a large number of these unit cells in series. In this case, naturally, it is considered that there is a variation in the battery group voltage, and further, the characteristics change due to a temperature change.

  When a plurality of battery groups having such characteristic variations are connected in parallel and charged and discharged at once, a large charge / discharge current difference is expected to occur between the battery groups. Applicable when charge / discharge current exceeds the allowable value due to dispersion of individual battery groups during charge / discharge operation as a protection measure against deterioration and damage due to characteristic dispersion when charging / discharging multiple battery groups connected in parallel. It is necessary to protect the battery group by stopping the charging or discharging of the abnormal battery group. Details of such a battery protection operation are disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-168259 (there is also a Japanese Patent Application No. 2005-266775 as a prior application), and this invention is implemented in the same manner as this. And

Explanatory drawing explaining embodiment of this invention Explanatory drawing explaining other embodiment of this invention The block diagram which shows the charging / discharging system which implements FIG. 1 or FIG. Conventional charging operation explanatory diagram corresponding to FIG. Conventional charging operation explanatory diagram corresponding to FIG.

Explanation of symbols

  1 to 2 (B1 to Bn) ... storage battery, 3 to 4 (SW1 to SWn) ... mechanical contact switch, 5 to 6 (Q1 to Qn) ... semiconductor switch, 7 to 8 (D1 to Dn) ... diode, 9 to 10, 14, 19, 23 (SH1 to SHn, SHB, SHG) ... current detector, 11 to 13, 21 (VD1 to VDn, VDB, VDG) ... voltage detector, 15, 20, 24, 27, 29 to 31, 35 (SWB, SWGH, SWLH, SWMH, SWC to SWF, SWG) ... switch, 16 ... generator (G), 17 ... generator field (Gf), 22 ... auxiliary power system (L), 25 ... Propulsion motor (M), 28 ... Battery charge / discharge & status monitoring and control device, 32 ... Voltage setting device, 33 ... Current setting device, 34 ... Generator control device, 36 ... Signal

Claims (1)

In the charge and discharge method that charges and discharges multiple batteries connected in parallel at the same time,
In the initial stage of the final charging area, charging is performed by changing the charging voltage or charging current step by step using the multi-stage constant voltage charging method or multi-stage constant current charging method, and the battery voltage or battery current is about 95% of the fully charged state. If the battery reaches full charge, it switches from the multi-stage constant voltage charging system or multi-stage constant current charging system to the constant voltage pulse charging system or constant current pulse charging system, and switches the battery in time series to perform pulse charging. The battery charging and discharging method is characterized in that the charging is completed sequentially.

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