JP2007110887A - Charge/discharge switching method for battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve reduction in size, in weight and also in cost by omitting or downsizing a cooling device, while reducing a conduction loss to a semiconductor switch, and to eliminate the generation of mechanical friction or operation sounds involved in the frequent on/off-operation of a mechanical contact switch. <P>SOLUTION: Charge/discharge switching circuits, in which mechanical contact switches 3 to 4, semiconductor switches 5 to 6, and diodes 7 to 8 are connected in parallel, are connected in series to respective batteries 1 to 2. The mechanical contact switches 3 to 4 are employed to conduct currents at a discharge time of large current conduction and in a large current charge operation region to reduce the conduction loss. The semiconductor switches 5 to 6 are employed to conduct currents in a small current charge operation region to reduce the conduction loss, thereby eliminating the operation sounds resulting from the on/off-operation at pulse charging and the off-operation upon the completion of charging. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric propulsion system that includes a storage battery as a primary power source, and includes a power supply device including a generator that charges the storage battery, and a propulsion motor and auxiliary motors required for system operation. The present invention relates to a switch system for connecting and disconnecting battery circuits in each operation of discharging, discharging and floating operations.

FIG. 12A shows a conventional example of a battery charge / discharge switch system. This method is disclosed in, for example, Patent Documents 1 to 3, which is hereinafter referred to as a semiconductor type.
In this method, the semiconductor switches Q1 to Qn are turned on when charging the battery, and the semiconductor switches Q1 to Qn are turned off and discharged via the diodes D1 to Dn when discharging the battery. However, this method has a problem that energization loss of Q1 to Qn during charging and energization loss of D1 to Dn during discharging are large, and cooling of the semiconductor switches Q1 to Qn and the diodes D1 to Dn is necessary.
Therefore, the applicant has proposed a system disclosed in Patent Document 4 as shown in FIG. This uses mechanical contact switches SW1 to SWn instead of the semiconductor switches Q1 to Qn to reduce energization loss and eliminate the need for a cooling device.

JP-A-2005-080318 Japanese Patent Laid-Open No. 2005-143201 JP 2005-168259 A JP-A-2005-312195

However, the method disclosed in Patent Document 4 also involves frequent ON / OFF operations such as pulse charging operation by turning ON / OFF the mechanical contact switches SW1 to SWn, or OFF operation of individual batteries that have completed charging. There is a problem of mechanical wear of the mechanical contact switch and generation of operation noise.
Accordingly, an object of the present invention is to reduce energization loss to reduce the size, weight, and cost by omitting or reducing the cooling device, and to reduce mechanical loss and mechanical wear caused by frequent ON / OFF operations of mechanical contact switches. It is to eliminate the generation of operating noise.

  In order to solve such a problem, according to the first aspect of the present invention, in the charge / discharge circuit for charging / discharging the battery, a charge / discharge switch circuit in which a mechanical contact switch, a semiconductor switch, and a diode are connected in parallel is provided, In the discharging and large current charging operation region, the energization is performed through the mechanical contact switch, while in the small current charging operation region, the energization by the semiconductor switch and the on / off operation are performed to reduce the energization loss and the mechanical type. It is characterized by suppressing the operation sound when the contact switch is turned on and off.

  In the invention of claim 1, the charge / discharge switch circuit is a charge / discharge switch circuit in which a semiconductor switch is connected between the midpoints of the diode bridge circuit, and mechanical contact switches are connected in parallel to both ends of the diode bridge circuit. (Invention of Claim 2) or, in the invention of Claim 2, by turning off the semiconductor switch and the mechanical contact switch, the battery is fed regardless of the direction of current flow. It can be separated from the bus (invention of claim 3).

According to the first aspect of the present invention, a charge / discharge switch circuit in which a mechanical contact switch, a semiconductor switch, and a diode are connected in parallel is connected in series to each battery. The mechanical contact switch is energized to reduce energization loss, and in the small current charging operation region, the energization loss is reduced as energization by the semiconductor switch, resulting from on / off operation in pulse charging and off operation when charging is completed. The operation sound can be eliminated.
Further, when shifting from the charging operation to the discharging operation, it is possible to prevent a power interruption from occurring by discharging through the diode during the operation delay period until the mechanical contact switch is turned on.

  According to the invention of claim 2 or 3, in addition to the advantages of the invention of claim 1, by turning off the semiconductor switch and the mechanical contact switch, the battery is fed regardless of the direction of current flow. Can be disconnected from the circuit bus. As a result, the abnormal battery can be individually disconnected from the power supply circuit bus, so that the system operation can be continued without interrupting the power supply from the battery.

FIG. 1 is a block diagram showing an embodiment of the present invention.
As shown in the drawing, the charge / discharge switch circuit is characterized in that a mechanical contact switch (SW), a diode (D), and a semiconductor switch (Q) are connected in parallel. The basic operation is that the discharge operation and energization in the large charging current region are performed by the mechanical contact switch (SW), and the mechanical contact is performed in the small charging current 0.05C (1C: 1 hour rate discharge) region of the battery final charging operation. If the switch is turned off and only the semiconductor switch (Q) is energized, the energization loss of the semiconductor switch can be drastically reduced to about 2 to 300 W (previously about 1 to 10 kW), so the cooling device can be omitted or reduced in size. In addition, mechanical wear and noise generation associated with the ON / OFF operation can be eliminated.

  2 is a time chart of charging / discharging operation of FIG. 1, FIG. 3 is an explanatory diagram of operation of constant current → constant current → constant voltage charging, and FIG. 4 is an explanatory diagram of charging operation of constant current → constant voltage → constant current pulse. The operation of FIG. 1 will be described with reference to the drawings. 5 shows the operation at the time of battery discharge, and the maximum discharge current shows that about 1 C flows from the battery to the load. FIG. 6 shows the operation at the time of battery charging, and the maximum current for charging is 0.25 C. This indicates that a charging current of about 0.05 C is obtained in the final charging region.

First, as shown in FIG. 3, a case where charging is performed in a constant current → constant current → constant voltage charging method will be described.
In this case, the charging switch 29 (SWC) in FIG. 1 is preset in the order of constant current → constant current → constant voltage, and charging currents IBaΣ and IBbΣ = IBcΣ in each step are preset by the current setting unit 33 (VRI), and The mechanical contact switches 3 (SW1) to 4 (SWn) connected in series to the battery are turned on by a command from the battery charge / discharge & state monitoring controller 28. Further, the generator 16 (G) is operated by setting the generator operation switch 35 (SWG) in FIG. 1 to “operation”, and battery charging is started by the generator constant current control from the point a shown in FIG.

Since the detection signal of the battery voltage detector 13 (VDB) is input to the battery charge / discharge & state monitoring control device (simply abbreviated as device) 28, it is determined that the battery voltage has reached the VBb point. The device 28 gives a current command for the charging current IBbΣ to the generator control device 34 as a signal 36, whereby the generator performs constant current control of the current set value IBbΣ. At this time, the mechanical contact switches 3 (SW1) to 4 (SWn) are kept ON.
Further, when the device 28 determines that charging has progressed and the battery voltage has reached the VBc point shown in FIG. 3, the device 28 gives an ON command to the semiconductor switches 5 (Q1) to 6 (Qn) (c in FIG. 2). Point reference), while giving an OFF command to the mechanical contact switches 3 (SW1) to 4 (SWn) (see point c1 in FIG. 2), the battery voltage detection value VBc and the constant voltage control command from the device 28 as a signal 36 The generator voltage is supplied to the generator control device 34 and the constant voltage controlled generator voltage is supplied to the battery.

That is, as shown in FIG. 2, the mechanical contact switches 3 (SW1) to 4 (SWn) and the semiconductor switches 5 (Q1) to 6 (Qn) are overlapped between points c to c1. By giving a command from 28, the power feeding circuit is prevented from being disconnected, and the point c to point f in FIG. 3 are charged with a constant voltage.
From the battery in which charging progresses and the charging current (IBb1 to IBbn) of each battery reaches a preset charging current, the semiconductor switch of the corresponding battery is turned off to end the charging. At the point f (see FIGS. 2 and 3) when all the batteries have finished charging, all the semiconductor switches are turned off, and the mechanical contact switches 3 (SW1) to 4 (SWn) are already turned off at the point c1. Therefore, all the batteries are disconnected from the feeder circuit bus. At this time, power is supplied to the load from the operating generator 16 (G).

  When stopping the generator 16 (G) from the above state, if the operation switch 35 (SWG) in FIG. 1 is set to “stop”, the generator control device 34 turns off the generator switch 20 (SWGH) ( 2), a generator stop signal is given to the device 28 as a signal 36. When the device 28 gives an ON command to the mechanical contact switches 3 (SW1) to 4 (SWn) (see the point g in FIG. 2), the mechanical contact switches 3 to 4 are turned on at the point g1 due to the ON operation delay time. It becomes a state. As a result, a disconnection occurs during the operation delay period from when the generator switch 20 is turned off (g point in FIG. 2) to when the mechanical contact switches 3 to 4 are turned on. However, since power is supplied from the battery to the load through the diodes 7 (D1) to 8 (Dn) connected in parallel with the mechanical contact switches 3 to 4, no instantaneous power interruption occurs.

  Further, when the discharge operation is shifted separately from the OFF signal of the generator switch 20, the discharge current flows through the diodes 7 (D1) to 8 (Dn), and this current is detected by the detector 14 (SHB). Then, an ON command is given from the device 28 to the mechanical contact switches 3 to 4. In other words, the mechanical contact switches 3 to 4 can be turned ON as a parallel (OR) signal of the stop signal from the operation switch 35 (SWG) and the signal from the detector 14 (SHB). 3-4 are turned on. Naturally, the semiconductor switch connected in parallel with this is set in the OFF state.

Next, when performing constant current → constant voltage → constant current pulse charging as shown in FIG. 4, constant current charging is started from point a in FIG. 2, and the battery voltage detected by the voltage detector 13 (VDB) is When the device 28 determines that the point b voltage VBb has been reached, a switching signal from constant current control to constant voltage control with VBb as the voltage setting value is given as a signal 36 from the device 28 to the generator control device 34. The generator is controlled at a constant voltage to supply the generator voltage to the battery.
When charging progresses and the device 28 determines that the detection signal from the battery current detector 14 has reached IBcΣ, a switching signal from constant voltage control to constant current control with IBc as the current set value is set as a signal 36. The generator current is supplied from 28 to the generator control device 34 and the constant current control is supplied to the battery.

  Here, the device 28 gives an OFF command to the mechanical contact switches 3 to 4 and an ON command to the semiconductor switches 5 (Q1) to 6 (Qn). At this time, when the pulse charge switch 30 (SWP) ON in FIG. 1 is selected, the semiconductor switches 5 (Q1) to 6 (Qn) are turned on and off in time series by a predetermined program, and the voltage of each battery From the battery that has reached the preset charge completion voltage VBf, the associated semiconductor switches are sequentially turned off to complete the charge. All the semiconductor switches are turned off at the point f in FIG. 2 and the point f in FIG. Accordingly, all the semiconductor switches are OFF, the mechanical contact switches 3 (SW1) to 4 (SWn) are already OFF at the time C1, and all the batteries are disconnected from the feeder circuit bus. Power is supplied from (G).

  Here, when the operation switch 35 (SWG) in FIG. 1 is “stopped” in order to stop the generator for some reason in the middle of the final charging range (see points h to l in FIG. 2), the generator control is performed. Since an OFF command is given from the device 34 to the generator switch 20 (SWGH) (point l in FIG. 2) and a stop signal 36 is given to the device 28, the device 28 is connected to the mechanical contact switches 3 (SW1) to 4 (SWn). ) Is given an ON command (point l in FIG. 2). However, the mechanical contact switches 3 (SW1) to 4 (SWn) are turned on at the point l1 in FIG. 2 due to operation delay. In this case as well, since power is supplied from the battery to the load via the diodes 7 (D1) to 8 (Dn) connected in parallel, no power interruption occurs. Naturally, the semiconductor switches connected in parallel are turned off.

The floating operation (operation in which the charging / discharging current of the battery is 0) is shown at points n to o in FIG.
When the floating operation switch 31 (SWF) in FIG. 1 is turned on at n point in FIG. 2, the device 28 gives an OFF command to the mechanical contact switches 3 (SW1) to 4 (SWn), while the generator voltage VG is the battery voltage. A voltage signal 36 such that VG + ΔVG, which is slightly higher than VB, is given to the generator control device 34 to control the generator voltage. That is, the mechanical contact switches 3 (SW1) to 4 (SWn) and the semiconductor switches 5 (Q1) to 6 (Qn) are OFF, and the generator voltage is also blocked by the diodes 7 (D1) to 8 (Dn). Therefore, each battery is in a floating state.

  From the above floating operation state, when there is a sudden increase in load that supplies power to the load in parallel operation of the battery and the generator (see point o in FIG. 2), the mechanical contact switch 3 (SW1) ˜ 4 (SWn) and semiconductor switches 5 (Q1) to 6 (Qn) are OFF, the battery is discharged through the diodes 7 (D1) to 8 (Dn), and −IBΣ indicated by a dotted line in FIG. 1 is supplied to the load from the generator 16 (G). That is, IΣ2 = IG + (− IBΣ) is supplied to the load. At this time, since the battery shifts to discharge through the diodes 7 (D1) to 8 (Dn), the device 28 determines the detection signal of the battery current detector 14 (SHB), and the mechanical contact switch 3 (SW1) to 4 (SWn) is given an ON command (see point o in FIG. 2). Also in this case, the mechanical contact switches 3 (SW1) to 4 (SWn) are turned on at the point p in FIG. 2 due to the operation delay of the mechanical contact switches 3 (SW1) to 4 (SWn). ) To 8 (Dn).

  In addition, as a large-capacity system using a storage battery as a primary power source, a lead storage battery and an alkaline storage battery have been frequently used conventionally, and 200 to 300 cells of large-capacity single cells are connected in series to form a battery group. In general, a system in which four groups are connected in parallel has been used, but in recent years, studies for applying a lithium ion battery having a high energy density to a large capacity system using a storage battery as a primary power source have been advanced. However, large-capacity lithium-ion batteries intended for use in large-capacity systems are in the research and development stage, and the future trend is unknown, but at this stage, many small and medium-capacity cells are connected in series and in parallel. It is considered to be done.

  It is considered that there is a characteristic variation in each single cell constituting the large capacity system as described above, and when a battery system in which a plurality of battery groups are connected in parallel by connecting a large number of the single cells in series and parallel is formed. Naturally, it is considered that the battery group voltage varies, and the characteristics change due to temperature changes. When a plurality of battery groups having such characteristic variations are connected in parallel and collectively charged / discharged, it is expected that a large charge / discharge current difference occurs between the battery groups.

In addition, lithium-ion batteries, among other storage batteries, have the advantage of high energy density. On the other hand, “risk of ignition and explosion due to overcharge” has been pointed out, and in addition, “deterioration of battery characteristics due to overdischarge is significant. , Etc. are reported, careful attention and strict monitoring and control are required for charging and discharging, and when charging and discharging a plurality of battery groups connected in parallel, due to characteristic variations. Appropriate protection against deterioration and damage is required.
As a protective measure against deterioration and damage due to characteristic variations when charging and discharging a plurality of battery groups connected in parallel, the charge / discharge current exceeds the allowable value due to variations in individual battery groups during charge / discharge operations. In such a case, it is conceivable that the charging or discharging of the corresponding abnormal battery group is stopped to protect the battery group.

  In the battery system having the configuration shown in FIG. 1 described above, an example in which a protective measure corresponding to the characteristic variation of each battery group is applied will be described. The battery system of FIG. 1 has a configuration in which a plurality of batteries 1 (B1) to 2 (Bn) are connected in parallel to a power supply circuit bus via charge / discharge switch circuits. Each of the batteries 1 (B1) to 2 (Bn) is actually a battery group in which a large number of single cells are connected in series. In such a battery system of FIG. 1, during the charging operation, a plurality of batteries 1 connected in parallel as shown in FIG. 3 in the large current and medium current charging regions of points a to b to c in FIG. 2 ( B1) to 2 (Bn), when performing charging in a continuous current mode in constant current mode, the charging currents IB1 to IBn detected by the current detectors 9 (SH1) to 10 (SHn) of each battery are the allowable charging currents. When the device 28 determines that the variation range has been exceeded, the mechanical contact switches 3 (SW1) to 4 (SWn) corresponding to the abnormal battery are turned off to disconnect the abnormal battery, and a current command to be given to the generator control device 34. The value, that is, the total charging current command value is decreased by an amount corresponding to the number of disconnected batteries so that the charging current of the healthy battery does not increase and an alarm is issued.

  The allowable variation range of the charging current is, for example, an average current value Ime (= IBΣ / m) obtained by dividing the total charging current IBΣ by the number m of the batteries connected by the mechanical contact switch in the ON state at that time, for example ± 10%. The number m of denominator batteries in the parentheses of the above average value Ime is m = n when the batteries 1 (B1) to 2 (Bn) are all connected by the mechanical contact switches in the ON state. Each time the disconnection control for the abnormal battery is performed, the number m of batteries decreases. Further, as the current value of the total charging current IBΣ used for characteristic variation determination, either the above-mentioned total charging current command value or the total charging current detection value detected by the current detector 14 (SHB) may be used. The total charge current detection value is more preferable in that it is unified with the case of batch continuous charging in the constant voltage mode described later.

  Further, during the charging operation, the batteries 1 (B1) to 2 (Bn) connected in parallel in the medium current charging region at points b to c in FIG. Instead of the collective continuous charge, collective continuous charge in the constant voltage mode as shown in FIG. 4 may be performed. Also in this case, if the device 28 determines that the charging currents IB1 to IBn detected by the current detectors 9 (SH1) to 10 (SHn) of each battery are out of the allowable variation range of the charging current, the abnormal battery is identified. Corresponding mechanical contact switches 3 (SW1) to 4 (SWn) are turned off to disconnect the abnormal battery and issue an alarm.

  The allowable variation range of the charging current is the average current value obtained by dividing the total charging current IBΣ detected by the current detector 14 (SHB) by the number m of batteries connected by the mechanical contact switch in the ON state at that time. For example, ± 10% of Ime (IBΣ / m). The number m of denominator batteries in the parentheses of the above average value Ime is m = n when the batteries 1 (B1) to 2 (Bn) are all connected by the mechanical contact switches in the ON state. Each time the disconnection control corresponding to the abnormal battery is performed, the number of batteries m decreases. In the case of batch continuous charging in the constant voltage mode, control for reducing the current command value to be given to the generator controller 34 corresponding to the number of disconnected batteries, as in batch continuous charging in the constant current mode. Is unnecessary.

  In the final charging region, when performing batch continuous charging in the constant voltage mode for a plurality of batteries 1 (B1) to 2 (Bn) connected in parallel as shown in FIG. If the device 28 determines that the charging currents IB1 to IBn detected at 9 (SH1) to 10 (SHn) are out of the allowable variation range of the charging current, the semiconductor switches 5 (Q1) to 6 corresponding to the abnormal battery Turn off (Qn) to disconnect the abnormal battery and issue an alarm.

  The allowable variation range of the charging current is determined by dividing the total charging current IBΣ detected by the current detector 14 (SHB) by the number m of the batteries connected by the semiconductor switch in the ON state at that time. = IBΣ / m), for example, ± 10%. The number of batteries m in the denominator in the above parentheses of the average value Ime is m = n when the batteries 1 (B1) to 2 (Bn) are all connected by the semiconductor switch in the ON state. The number m of batteries decreases each time the charge termination control for the battery whose charge current has reached the preset charge completion level current value IBd by the semiconductor switch OFF and the disconnection control corresponding to the abnormal battery as described above are performed. I will do it. Also in the final charge region, in the case of batch continuous charge in the constant voltage mode, the current command value to be given to the generator controller 34 is equivalent to the number of disconnected batteries as in the batch continuous charge in the constant current mode. Therefore, it is not necessary to perform control for lowering the amount.

  Further, in the final charge region, when performing constant current pulse charging, that is, pulse charging in the constant current mode, for a plurality of batteries 1 (B1) to 2 (Bn) connected in parallel as shown in FIG. If the device 28 determines that the battery voltages VB1 to VBn detected by the voltage detectors 11 (VD1) to 12 (VDn) of each battery are out of the allowable variation range of the charging voltage, the semiconductor switch corresponding to the abnormal battery 5 (Q1) to 6 (Qn) are turned OFF, the abnormal battery is removed from the target of pulse charging, charging is stopped, and an alarm is issued.

  The allowable variation range of the charging voltage is, for example, an average value Vme (= (VB1 +... + VBn) / m) obtained by storing the battery voltage detection values VB1 to VBn of each battery in one cycle immediately before the pulse charging control. ± 10%. Here, as the battery voltage detection values VB1 to VBn used for characteristic variation determination, the battery voltage value detected when the semiconductor switch corresponding to the corresponding battery is turned on and charged, that is, the battery voltage during charging is used. Alternatively, the battery voltage value detected when the semiconductor switch corresponding to the corresponding battery is OFF, that is, the battery voltage at the time of opening may be used, but each battery in the state where it is incorporated in the battery system may be used. In terms of determining an effective characteristic variation, the former method using the battery voltage at the time of charging is more preferable than the latter method using the battery voltage at the time of opening.

  The number of batteries m of the denominator in the above parentheses of the average value Vme is m = n when the batteries 1 (B1) to 2 (Bn) are all subjected to pulse charging, and the battery voltage The number of batteries m decreases each time the charging end control for the battery that has reached the preset charging completion voltage VBf and the disconnection control for the abnormal battery as described above are performed. The charging current set value IBc in the pulse charging in the constant current mode is a current value set as a charging current to any one of the batteries, and the generator control device 34 corresponds to such a charging current set value IBc. Therefore, there is no need to reduce the current command value applied to the generator controller 34 by the amount corresponding to the number of disconnected batteries, as in the batch continuous charging in the constant current mode. is there.

  Further, in the final charge region, constant voltage pulse charging as shown in FIG. 7 is performed instead of constant current pulse charging as shown in FIG. 4 for a plurality of batteries 1 (B1) to 2 (Bn) connected in parallel. Sometimes it is done. FIG. 7 is an explanatory diagram of charging operation of constant current → constant current → constant voltage pulse. In this charging method, batch continuous charging in the constant current mode is performed in the large current and medium current charging regions from point a to point b to point c, and constant voltage pulse charging is performed in the final charging region from point c to point f. Performs pulse charging in constant voltage mode.

  That is, as shown in FIG. 7, from the point a, the batch continuous charging in the constant current mode is started with the total charging current command value that is the current command value to be given to the generator control device 34 being IBaΣ, and the voltage When the device 28 determines that the battery voltage detected by the detector 13 (VDB) has reached the voltage VBb (point b), the total charge current command value is changed to IBbΣ, and further in the constant current mode. When constant charge is performed and the device 28 determines that the battery voltage detected by the voltage detector 13 (VDB) has reached the voltage VBc (point c), the constant current control sets VBc as a voltage set value. A switching signal for voltage control is given as a signal 36 from the device 28 to the generator control device 34 so that the generator is controlled at a constant voltage, and pulse charge control is started.

  As pulse charge control, the device 28 sets the semiconductor switches 5 (Q1) to 6 (Qn) in time series according to a predetermined program in a state where an OFF command is given to the mechanical contact switches 3 (Sw1) to 4 (SWn). Turn on and off. The charging current of each of the batteries 1 (B1) to 2 (Bn) having characteristic variations decreases with time as shown in FIG. The batteries that have reached the current IBc at the charging completion level set in advance are sequentially disconnected from the target of pulse charging to complete the charging, and charging of all the batteries is completed at point f.

  In such constant voltage pulse charging in the final charging region, battery protection control based on characteristic variation determination is performed as follows. That is, if the device 28 determines that the charging currents IB1 to IBn detected by the current detectors 9 (SH1) to 10 (SHn) of each battery are out of the allowable variation range of the charging current, the battery corresponds to the abnormal battery. The semiconductor switches 5 (Q1) to 6 (Qn) are turned off, the abnormal battery is removed from the pulse charging target, charging is stopped, and an alarm is issued.

  The allowable variation range of the charging current is, for example, an average value Ime (= (IB1 +... + IBn) / m) obtained by storing the charging current detection values IB1 to IBn of each battery in one cycle immediately before the pulse charging control. ± 10%. Note that the number m of denominators in the above parentheses of the average value Ime is m = n when the batteries 1 (B1) to 2 (Bn) are all subjected to pulse charging, and the charging current The number of batteries m decreases each time the charge termination control is performed on the battery that has reached the current value IBc of the preset charge completion level and the disconnection control on the abnormal battery as described above. Further, in the case of pulse charging in the constant voltage mode, control for reducing the current command value to be given to the generator control device 34 by an amount corresponding to the number of disconnected batteries, as in batch continuous charging in the constant current mode, It is unnecessary.

  Also, when the device 28 determines that the discharge currents -IB1 to -IBn detected by the current detectors 9 (SH1) to 10 (SHn) of each battery are out of the allowable variation range of the discharge current during the discharge operation, The device 28 issues a warning signal and prompts processing / treatment such as turning off the external switch.

  The allowable variation range of the discharge current is an average value Ime (= −IBΣ / m) obtained by dividing the total discharge current detection value −IBΣ detected by the current detector 14 (SHB) by the number m of batteries connected in parallel. ), For example, ± 10%. Here, in particular, when power is supplied to the load only by battery discharge, in order to prevent the power supply from the battery to the load from being inadvertently stopped, even if a discharge current variation abnormality of a certain battery occurs, an alarm is first given. With only the output, the abnormal battery can be disconnected manually by making a judgment after fully grasping the situation of the entire system including the battery, generator and load. However, since the discharge during the discharge operation is performed via the diodes 7 (D1) to 8 (Dn), the charge / discharge switch circuit itself cannot disconnect the discharge.

For this reason, when the abnormal battery is disconnected at the time of discharging as an operation method of the battery system, the charge / discharge switch circuit is connected to the outside of each charge / discharge switch circuit corresponding to the batteries 1 (B1) to 2 (Bn). If the external switches SWD1 to SWDn as shown in FIG. 8A (not shown in FIG. 1) are provided in series, the abnormal battery can be disconnected by manually turning off the external switches SWD1 to SWDn. it can.
Further, when the abnormal battery is disconnected during the discharge as described above, the allowable variation range of the discharge current is the total discharge current detection value -IBΣ detected by the current detector 14 (SHB). For example, ± 10% of the average value Ime (= −IBΣ / m) obtained by dividing by the number m of the batteries connected by the switch. The number of batteries m in the denominator in the parenthesis of the average value Ime is m = n in the state where the batteries 1 (B1) to 2 (Bn) are all connected by the external switch in the ON state, and is disconnected from the abnormal battery. Each time the operation is performed, the number of batteries m decreases.

  As the external switches SWD1 to SWDn for disconnecting the battery at the time of the discharging operation, a mechanical contact switch having a small current loss is suitable in consideration of a large current at the time of the discharging operation, but a semiconductor switch is also applicable. is there. The mechanical contact switch applied to the external switches SWD1 to SWDn is always turned on and turned off only when the abnormal battery needs to be disconnected. For example, a switch such as a load switch or a circuit breaker may be used. Although it is good, it is preferable to use a switch having a function equivalent to a load disconnector on the assumption that some overcurrent interruption is required for opening an abnormal battery.

  As shown in FIG. 8A, the charge / discharge switch circuit comprising the mechanical contact switch SW1, the semiconductor switch Q1, and the antiparallel diode D1 corresponding to the battery B1 shown in FIG. External switches SWD1 are connected in series, and external switches SWD2 to SWDn including mechanical contact switches are provided for the batteries B2 to Bn as well as the battery B1. This mechanical contact switch is an electric drive type or electromagnetic drive type, and is a controllable switch that can be turned on and off by external signals SWD1dv to SWDndv as shown in FIG. In addition to manual operation at hand, remote manual operation while viewing the operating status of the entire system from the centralized monitoring control device may be possible.

  Next, FIG. 8B shows an example in which the external switches SWD1 to SWDn for battery separation during the discharging operation are constituted by semiconductor switches. The circuit of FIG. 8 (b) is a series connection circuit portion of a charge / discharge switch circuit comprising a mechanical contact switch SW1, a semiconductor switch Q1, and an antiparallel diode D1 and an external switch SWD1 corresponding to the battery B1 shown in FIG. The external switch SWD1 is constituted by a semiconductor switch circuit for discharge formed by connecting a semiconductor switch QR1 and a parallel diode DR1 having opposite polarities in parallel to the semiconductor switch Q1 and the parallel diode D1, respectively. The semiconductor switch QR1 is turned OFF by the OFF command QR1dv, and the discharge from the corresponding battery B1 is stopped. Then, similarly to the battery B1, the batteries B2 to Bn are provided with external switches SWD2 to SWDn made of a discharging semiconductor switch circuit.

  Further, depending on the configuration of the system including the battery, the generator, and the load, when a discharge current variation abnormality occurs in a certain battery, a controllable switch, that is, a discharge having a remote operation function as shown in FIG. The abnormal battery may be automatically disconnected using a mechanical contact switch for electric discharge or a semiconductor switch circuit for discharging as shown in FIG. 8B, and the disconnect control circuit is manually / automatically switched. It is preferable that the separation control mode can be selected in accordance with the operation status of the system.

  Moreover, since it is necessary to provide said external switch SWD1-SWDn for every battery connected in parallel, the case where it is difficult to provide external switch SWD1-SWDn by the restrictions on the installation space of a battery system, etc. can be considered. In such a case, instead of providing the external switches SWD1 to SWDn, the switch 15 (SWB) in FIG. 1 is configured by an air circuit breaker having a sufficient shut-off capability, and the batteries are connected in parallel. The battery parallel connection bus bar is used as a connection mechanism that is equivalent to a simple disconnector that facilitates manual battery disconnection work.In response to an abnormal discharge current variation of a battery, an alarm was issued. The switch 15 (SWB) can be turned off, and then the abnormal battery can be disconnected by manual operation using the battery parallel connection bus bar.

  Assuming that an internal short circuit has occurred in a series cell that constitutes a battery, such a state reduces the series electromotive voltage eB of the battery, resulting in an apparent discharge current compared to other healthy batteries. Since the battery is in an abnormal state of decreasing, an alarm is issued by an abnormal state detection signal by the discharge current variation determination process as described above. Then, according to the situation determination based on this alarm, the corresponding external switch among the external switches SWD1 to SWDn can be turned off manually to disconnect the corresponding abnormal battery.

  Further, as described above, depending on the configuration of the system including the battery, the generator, and the load, the abnormal battery can be disconnected automatically by using the controllable external switches SWD1 to SWDn. In both cases of manual disconnection and automatic disconnection, since the generator voltage and current inflow from other healthy batteries are blocked, safe operation of the battery system continues without affecting other healthy circuits. Is done. In the case of abnormal battery disconnection by the discharging semiconductor switch circuit shown in FIG. 8B, diodes D1 to Dn and DR1 to DRn connected in reverse parallel to the semiconductor switches Q1 to Qn and QR1 to QRn, respectively, Generator voltage and current inflow from other healthy batteries are blocked.

  By the way, in the charge / discharge switch circuit of FIG. 1, as a solution to the problem that even if an abnormality occurs in some of the batteries during the discharge operation, the corresponding batteries cannot be completely disconnected from the feeder circuit bus, as described above. In addition, a charge / discharge switch circuit comprising a mechanical contact switch SW1 (SWn), a semiconductor switch Q1 (Qn) and an antiparallel diode D1 (Dn) is added to the discharge mechanical contact switch circuit SWD1 (SWDn) shown in FIG. Alternatively, a configuration in which the semiconductor switch circuits SWD1 (SWDn) for discharging shown in FIG. 8B are connected in series can be applied, but a configuration as shown in FIG. 9 can also be applied in addition to this.

  FIG. 9 is a block diagram showing a modified example of FIG. 1. In the charge / discharge switch circuit of FIG. 1, even if the mechanical contact switch and the semiconductor switch are turned off, the battery is connected via a diode connected in parallel to them. 1 is connected to the power supply circuit bus, so that even if some battery malfunctions during the discharging operation, the charge / discharge switch circuit in FIG. Is replaced with the charge / discharge switch circuit A1 (An). The charge / discharge switch circuit A1 (An) has a semiconductor switch Q1 (Qn) connected between the midpoints of the diode bridge circuit composed of diodes D11 to D14 (Dn1 to Dn4), and mechanical contacts at both ends of the diode bridge circuit. The switch SW1 (SWn) is connected in parallel.

  In the diode bridge circuit, as shown in FIG. 9, diodes D11 (Dn1) and D14 (D14 (Dn1) and D14 (Dn1)) forming the first and second arms on the anti-battery side (that is, the feeder circuit bus side), respectively. Dn4) are oppositely connected to each other in the forward direction during charging and discharging and commonly connected to the end terminal on the anti-battery side, and form first and second arms on the battery side, respectively. The diodes D13 (Dn3) and D12 (Dn2) are connected in common to the end terminals on the battery side with opposite polarities so as to be in the forward direction during discharging and charging, respectively. In the diode bridge circuit, the cathode of the diode D11 (Dn1) of the anti-battery side first arm that is forward during charging and the cathode of the diode D13 (Dn3) of the battery side first arm that is forward when discharging. Are connected at the first midpoint, and the anode of the diode D14 (Dn4) of the anti-battery side second arm that is forward during discharging and the diode D12 (Dn2) of the battery side second arm that is forward when charging. ) At the second midpoint.

  A semiconductor switch Q1 (Qn) is connected between the first midpoint and the second midpoint of the diode bridge circuit. As a semiconductor element constituting the semiconductor switch Q1 (Qn), for example, an IGBT (Insulated Gate Bipolar Transistor) or the like can be used. When the IGBT is used, the collector of the semiconductor switch Q1 (Qn) is the first of the diode bridge circuit. 1 is connected to the middle point side of the semiconductor switch Q1, and the emitter of the semiconductor switch Q1 (Qn) is connected to the second middle point side of the diode bridge circuit. A mechanical contact switch SW1 (SWn) is connected in parallel between both ends of the diode bridge circuit, that is, between the end terminal on the anti-battery side and the end terminal on the battery side.

  The semiconductor switch is configured by suppressing the reverse voltage generated between the collector and emitter of the semiconductor switch due to the surge voltage caused by the circuit inductance when the semiconductor switch is turned off during pulse charging performed by turning the semiconductor switch on and off. In the configuration of FIG. 9, the diode bridge circuit composed of the diodes D11 to D14 (Dn1 to Dn4) has a surge protection function for the semiconductor switch Q1 (Qn). ing. That is, the diode D11 (Dn1) provided between the collector of the semiconductor switch Q1 (Qn) and the anti-battery side end terminal against the surge voltage when the semiconductor switch is OFF in the pulse charge as described above, The diode D12 (Dn2) provided between the emitter of the semiconductor switch Q1 (Qn) and the battery side end terminal is reverse-biased, and the collector of the semiconductor switch Q1 (Qn) and the battery side end terminal The diode D13 (Dn3) provided therebetween and the diode D14 (Dn4) provided between the emitter of the semiconductor switch Q1 (Qn) and the non-battery side end terminal are forward biased. The reverse voltage generated between the collector and emitter of Q1 (Qn) is suppressed.

  Further, as shown in FIG. 9, a diode D1 (Dn) may be connected in antiparallel to the semiconductor switch Q1 (Qn), and the semiconductor switch Q1 (Qn) in the charge / discharge switch circuit A1 (An) is connected to the semiconductor switch Q1 (Qn). When the wiring with the diode bridge circuit is long and the inductance is large, the diode D1 (Dn) functions effectively as a diode for surge protection for the semiconductor switch Q1 (Qn). When a parasitic diode is formed as the element structure of the semiconductor switch, this parasitic diode can be used as the diode D1 (Dn). However, when the charge / discharge switch circuit A1 (An) is configured such that the wiring between the semiconductor switch Q1 (Qn) and the diode bridge circuit is shortened, surge protection means for the semiconductor switch Q1 (Qn) As long as there is a diode bridge circuit as described above.

By configuring the charge / discharge switch circuit as shown in FIG. 9, for example, when an abnormality occurs in the battery B1, both the mechanical contact switch SW1 and the semiconductor switch Q1 in the charge / discharge switch circuit A1 corresponding to the abnormal battery B1 are turned off. By doing so, the forward current (during charging) of the diodes D11 and D12 and the forward current (during discharging) of the diodes D13 and D14 are prevented from flowing, and the abnormal battery B1 is removed from the feeder circuit bus. It becomes possible to separate.
Since the rest of the configuration is the same as that of FIG. 1, differences from FIG. 1 will be mainly described below with reference to FIGS. 10 and 11.

Charging Operation FIG. 10 is an explanatory diagram showing the operation of the configuration of FIG. 9 in a time chart. FIG. 10A shows charging in the large current charging region and the small current charging region, and in the middle of the small current charging region. The operation when the generator is stopped before the completion of charging is shown in the time chart. In FIG. 10 (a), in the large current charging region before time t0, the semiconductor switches Q1 to Qn are turned off and the mechanical contact switches SW1 to SWn are turned on to supply a large charging current while shorting the semiconductor switch circuit. This is intended to reduce energization loss. When charging proceeds and reaches time t0 in FIG. 10A, the semiconductor switches Q1 to Qn are turned on at t0 and the mechanical contact switches SW1 to SWn are turned off at t1, and charging in the small current charging region is started. .

  As described above, the semiconductor switch is turned on by providing a period (t0 to t1) in which both the mechanical contact switch and the semiconductor switch are turned on so that the semiconductor switch is turned on prior to turning off the mechanical contact switch. (T0), since the mechanical contact switch is still in the ON state, it is only necessary to short-circuit the weak voltage drop generated in the mechanical contact switch just before the semiconductor switch is turned on by the semiconductor switch. Therefore, the semiconductor switch can be turned on in a substantially non-energized state, and the duty of closing the semiconductor switch can be greatly reduced. Also, when the mechanical contact switch is turned off (t1), the semiconductor switch is already turned on, so the mechanical contact switch only needs to open the voltage drop between the weak contacts. Open circuit duty can be greatly reduced. This operation is the same as the operation at time c-c1 of FIG. 2 showing the operation of FIG.

In addition, when the generator 16 (G) is stopped for some reason in the small current charging region of cf shown in FIG. 2 and t0 to tx22 shown in FIG. 10A, the configuration of FIG. The time until the contact of the mechanical contact switch is turned on, such as the points ˜g1 and ˜m, does not interrupt the power supply to the load by energizing the diodes 7 (D1) -8 (Dn). To.
On the other hand, since the diode energization circuit is not provided in the configuration of FIG. 9, after the generator operation switch 35 (SWG) is stopped at time tx2, as shown in FIG. A generator stop command (signal 36) is given to the charge / discharge & state monitoring control device 28, and before the generator stop control, the mechanical contact switch is turned on at time tx21 in accordance with commands 37 to 38 from the device 28, and time tx22. Then, at time t2, the generator voltage is lowered by the generator stop control command and the generator circuit switch 20 (SWGH) is turned OFF to stop the generator 16 (G). Make sure that the power supply to the load is not interrupted. In this respect, the configuration of FIG. 1 is different from the configuration of FIG.

  Next, FIG.10 (b) shows the operation | movement in the case of charging to a full charge state and stopping a generator after completion of charge with a time chart. As shown in FIG. 10B, when the charging is performed from the large to medium current charging region (to t10) to the small current charging region (t11 to t12) and charging is performed to the fully charged state in the small current charging region, the small current charging is performed. When shifting to the region (t11 to t12), the semiconductor switch is turned on (continuous constant current charge or continuous constant voltage charge), or the semiconductor switch corresponding to each battery is turned on and off in time series (constant current pulse charge / constant voltage pulse). Charge) to charge the battery, and in continuous constant voltage charge, constant current pulse charge, and constant voltage pulse charge, the charge switch is controlled to turn off the semiconductor switch sequentially from the fully charged battery and disconnect it from the charge target. In continuous constant current charging, when the voltage (VB) of the power supply circuit bus connected to each battery reaches a predetermined value, the semiconductor switch of each battery is turned off. To complete the charging Te. When the semiconductor end switches of all the batteries are turned off by the charging end control as described above, the charging of all the batteries is completed (time t12). When charging is completed, all the batteries are disconnected from the power supply circuit bus (mechanical contact switch OFF, semiconductor switch OFF in the charge / discharge switch circuits A1 to An shown in FIG. 9), but power supply to the load in this state is It is performed from the generator 16 (G) (time t12 to t31).

  In this state, as shown in FIG. 10B, when the generator operation switch 35 (SWG) is stopped (time t3), the generator stop command is sent from the generator control device 34 to the battery charge / discharge & state monitoring control device 28. (Signal 36) is given, and before the generator stop control, the mechanical contact switches of the charge / discharge switch circuits A1 to An provided in the respective batteries are turned ON by commands 37 to 38 from the device 28. At this time, since it is not necessary to turn on the semiconductor switch for the discharge operation corresponding to the stop of the generator, an ON command is not given to the semiconductor switch. Since there is an operation time delay (t3 to t31) until the mechanical contact switch is turned on, the mechanical contact switch is turned on after t31 so that power supply is not interrupted during this operation delay time (t3 to t31). After the generator controller 34 confirms that it is turned on by the signal 36 from the battery charge / discharge & state monitoring controller 28, the generator controller 34 lowers the generator voltage by the generator stop control command at time t4. At the same time, the generator circuit switch 20 (SWGH) is turned off to stop the generator 16 (G). That is, since the generator and the battery are connected in parallel during the period t31 to t4, the power supply to the load is not interrupted.

On the other hand, in the configuration of FIG. 1, as described in the paragraph [0014] above, when the generator is stopped in the mechanical contact switch OFF state and the discharge operation is started, the mechanical contact switch shown in FIG. 2 is turned on. The operation time delay time (g to g1) is energized by the diodes 7 (D1) to 8 (Dn) connected in parallel with the mechanical contact switch, and the diode is turned on at the time point g1 when the contact of the mechanical contact switch is turned on. Short circuit and energize with mechanical contact switch.
On the other hand, in the configuration of FIG. 9, since the discharge circuit by the diode as shown in FIG. 1 is not formed, the power supply to the load is interrupted by stopping the generator after the contact of the mechanical contact switch is turned ON. It does not occur. In this respect, the configuration of FIG. 1 is different from the configuration of FIG.

About Floating Operation According to the floating operation of the configuration of FIG. 1, the semiconductor element Q and the mechanical contact switch are both turned off while the generator voltage VG is set slightly higher than the battery voltage VB. The generator voltage VG is blocked by the diode D connected in parallel to obtain a floating operation state.
On the other hand, in the configuration of FIG. 9, by turning off both the semiconductor switches Q1 to Qn and the mechanical contact switches SW1 to SWn, the battery can be disconnected from the feeder circuit bus regardless of the operating state of the battery. it can.

  FIG. 10C illustrates a floating operation in the configuration of FIG. 9 with a time chart. When the floating operation switch 31 (SWF) is turned on in FIG. 9, the semiconductor switches Q1 to Qn are turned off at time t5 in FIG. 10C, and then the mechanical contact switches SW1 to SWn are turned off at time t51. Since the energization path of D11 (Dn1) → semiconductor element Q1 (Qn) (OFF) → diode D12 (Dn2) is not formed and the mechanical contact switch SW1 (SWn) is also OFF, the battery is disconnected from the feeder circuit bus. It is cut off and becomes a floating operation state. In this floating operation state, since the battery is disconnected from the power supply circuit bus, power is supplied from the generator 16 (G) to loads such as the propulsion motor 25 (M) and the auxiliary power system 22 (L) ( Time t51 to t61). After that, if the floating operation switch 31 (SWF) is turned off at time t6, the mechanical contact switches SW1 to SWn are turned on (contacts are turned on at time t61 slightly delayed from time t6), and the battery is connected to the power supply circuit bus. The floating operation is released. As described above, when the floating operation switch 31 (SWF) is turned on to start the floating operation, the magnitude of the battery current immediately before the circuit is opened by turning off the mechanical contact switch after turning off the semiconductor switch. However, it is possible to reduce the opening duty of the semiconductor switch and to make the mechanical contact switch have the opening duty.

Regarding Discharge Operation In the discharge operation in the configuration of FIG. 9, the mechanical contact switches SW1 to SWn are turned on and the semiconductor switches Q1 to Qn are turned off, and power is supplied from the battery to the load. FIG. 11A shows the current path at this time, and FIG. 11B shows the current path in the discharge operation in the configuration of FIG. 1 for comparison.
In FIG. 11B, the discharge current −IB of the battery is a combined current of the current ISW flowing through the mechanical contact switch SW and the current ID flowing through the diode D. Generally, the resistance ratio of the mechanical contact switch in the ON state and the diode in the forward bias state is said to be 1: 100 or more. However, since the current ID also flows through the diode depending on the resistance ratio, the diode is short-circuited by the mechanical contact switch. Even so, diode loss and heat generation occur.

  On the other hand, in FIG. 11A, the current ID as in FIG. 11B does not flow through the semiconductor switch circuit composed of the diode and the semiconductor element. This is because the discharge current of the battery is blocked by the diode D12 in the reverse bias state or the semiconductor element Q1 in the OFF state. In other words, according to the switching method as shown in FIG. 11A, no current ID flows through the semiconductor switch circuit, so no loss occurs. When it is desired to disconnect individual batteries connected in parallel from the power supply circuit bus for any reason, the batteries are individually powered by turning off the semiconductor switches Q1 to Qn and the mechanical contact switches SW1 to SWn as described above. Can be disconnected from the circuit bus.

Battery Protection Operation This is described, for example, in Patent Document 3 above. In this method, the battery in which the abnormality has occurred can be disconnected from the power supply circuit bus during the charging operation, but the battery in which the abnormality has occurred cannot be disconnected from the power supply circuit bus during the discharging operation, and only an alarm is issued. . However, in the switch system as shown in FIG. 9, by turning off the semiconductor switch and the mechanical contact switch, the battery can be disconnected from the power supply circuit bus regardless of the direction of current flow, and the abnormal battery can be individually fed. Since it can be disconnected from the circuit bus, there is an advantage that the system operation by the healthy battery can be continued without interrupting the power supply from the battery.

  The configuration of the charge / discharge switch circuit A1 (An) in FIG. 9 is the charge / discharge comprising the mechanical contact switch SW1 (SWn), the semiconductor switch Q1 (Qn), and the antiparallel diode D1 (Dn) in FIG. Compared with the configuration of the switch circuit in which the discharge mechanical contact switch circuit SWD1 (SWDn) is connected in series to the switch circuit, the battery can be disconnected from the power supply circuit bus regardless of the direction of current flow, and This is the same in terms of small energization loss during the discharge operation. However, in order to enable remote operation according to a command from the battery charge / discharge & state monitoring control device 28, the mechanical contact switch can be electrically driven or electromagnetically driven and can be turned on and off by an external signal. In the case of a control switch, the external dimensions of the mechanical contact switch become large, which is a problem when there are restrictions on the installation space of the battery system. In this respect, the configuration of FIG. Since there is only one switch, the configuration is more preferable than the configuration shown in FIG. 8A, which requires two mechanical contact switches.

Configuration diagram showing an embodiment of the present invention Time chart showing charge / discharge operation of the battery of FIG. Operation explanation of constant current → constant current → constant voltage charging Charge operation explanatory diagram of constant current → constant voltage → constant current pulse Current-voltage characteristics during battery discharge Current-voltage characteristics when charging the battery Charge operation explanatory diagram of constant current → constant current → constant voltage pulse Explanatory diagram of discharge switch circuit Configuration diagram showing a modification of FIG. FIG. 9 is an operation explanatory diagram. Explanatory diagram of discharge operation in FIG. Configuration diagram showing a conventional battery charge / discharge system

Explanation of symbols

  1-2 (B1-Bn) ... accumulator, 3-4 (SW1, SWn) ... mechanical contact switch, 5-6 (Q1-Qn) ... semiconductor switch, 7-8 (D1-Dn) ... diode, 9- 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 charging / discharging & state monitoring control device, 32 ... voltage setting device, 33 ... current setting device, 34 ... generator control device, 36 ... signal, 37-38 ... command (signal), A1 to An: charge / discharge switch circuit.

Claims (3)

  In a charging / discharging circuit for charging / discharging a battery, a mechanical contact switch, a semiconductor switch, and a diode switch are provided in parallel, and the mechanical contact switch is used in discharging and large current charging operation areas where a large current is applied. On the other hand, in the small current charging operation region, the conduction loss by the semiconductor switch and the on / off operation are reduced, thereby reducing the conduction loss and suppressing the operation sound when the mechanical contact switch is on / off. Battery charge / discharge switch system.   2. The charge / discharge switch circuit is replaced with a charge / discharge switch circuit in which a semiconductor switch is connected between the middle points of a diode bridge circuit, and mechanical contact switches are connected in parallel at both ends of the diode bridge circuit. The charge / discharge switch system for the battery according to 1.   3. The battery charge / discharge switch according to claim 2, wherein the semiconductor switch and the mechanical contact switch are turned off so that the battery can be disconnected from the feeder circuit bus regardless of the direction of current flow. method.

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