JP4096261B2 - Battery protection system - Google Patents

Description

  The present invention is suitable for application to a so-called hybrid system, such as an electric vehicle or an electric propulsion ship, which includes a storage battery as a primary power source and a generator for charging the storage battery, and supplies power from the storage battery and the generator to power. The present invention relates to a battery protection method.

  In a large-capacity system using a storage battery as a primary power supply, a lead storage battery and an alkaline storage battery have been widely used in the past, and 200 to 300 cells of large-capacity single cells are connected in series to form a group, and 2 to 4 groups of this battery group are connected in parallel. What is connected is common. In addition, the lithium ion battery targeted by the present invention has a high energy density, and in recent years, it has been put into practical use in the small capacity field for consumer use and industrial use.

  However, large-capacity lithium-ion batteries intended for application to large-capacity systems are in the research and development stage, and future trends are unclear, but at this stage, many small and medium-capacity cells are connected in series and in parallel. It is thought to be done. In this case, it is considered that there is a characteristic variation in the unit cell, and when a battery system in which a plurality of unit cells are connected in series by connecting a plurality of unit cells in parallel, naturally, the cell group voltage is It is considered that there is variation, and the characteristics change due to temperature changes.

  When multiple battery groups with such characteristic variations are connected in parallel and charged and discharged together, a large charge / discharge current difference is expected to occur between the battery groups. For example, Patent Documents 1 to 3 propose a method of charging the battery while being divided into individual batteries or group batteries and switching them with a switch.

Japanese Patent Application Laid-Open No. 07-203634 (page 5-6, FIG. 1) Japanese Patent Laid-Open No. 2002-31439 (page 3, FIG. 1) Japanese Patent Laid-Open No. 11-313445 (page 5, FIG. 1)

Here, the characteristic variation of the battery will be considered.
(1) Variation during charging operation FIG. 3A is a circuit diagram illustrating the charging operation.
The charging currents + IB1 to + IBm flow for each individual battery group with respect to the illustrated batch charging current + IBΣ. The charging currents + IB1 to + IBm of each battery group vary from battery group to battery group. As shown in FIG. 4A, the constant current charging operation is expected to be as shown in FIG.

Taking the case of the constant voltage charging operation of FIG. 4A as an example, the charging current of each battery group that flows when a constant voltage is applied to the battery groups connected in parallel is expressed by the following equation. However, the external wiring resistance connected to the battery group is assumed to be equal.
+ IB = (VG-eB) / (RB + RL)
VG: Generator voltage, eB: Battery internal electromotive voltage, RB: Battery internal resistance, RL: Wiring resistance From the above formula, the variation in the charging current of each battery group is caused by the difference between the battery internal electromotive voltage eB and the battery internal resistance RB. It can be seen that if eB or RB is large, the charging current is small, and if eB or RB is small, the charging current is large. Hereinafter, the cause of variation in battery characteristics and the electrical causal relationship will be described.

(1-1) Battery Internal Electromotive Voltage eB: Small Battery internal electromotive voltage eB is generated due to variations in material and processing, and the charging current tends to increase as eB decreases. That is, even if the applied voltage is the same, a charging current difference is caused by the eB difference, but an abnormal current difference is expected to cause an abnormality in the battery.
(1-2) Battery internal resistance RB: Small The smaller the battery internal resistance RB, the larger the charging current tends to be. An extreme shortage of RB can cause a short circuit between electrodes, and the apparent charging current (short circuit current) is growing. That is, even with the same applied voltage, a charging current difference occurs due to the RB difference, and an abnormal current difference is expected to occur inside the battery.
(1-3) Battery internal resistance RB: Large The larger the battery internal resistance RB, the smaller the charging current tends to be, and an extreme increase in RB is considered to be a disconnection, and the apparent charging current is small, or Not flowing. That is, even if the applied voltage is the same, a charging current difference occurs due to the RB difference, but an abnormal current difference is expected to occur inside the battery.

(2) Variation during discharge operation FIG. 3B is a circuit diagram for explaining the discharge operation.
With respect to the illustrated collective discharge current -IBΣ, discharge currents -IB1 to -IBm flow for each individual battery group. The discharge currents -IB1 to -IBm of each battery group are shown in FIG. There are variations and it is expected that they will flow with a difference in current.

Taking the discharge operation of FIG. 5 as an example, the discharge current of each battery group is expressed by the following equation. However, the external wiring resistance connected to the battery group is assumed to be equal.
−IB = −eB / (RB + RL + RLΣ)
eB: battery internal electromotive force, RB: battery internal resistance, RL: wiring resistance RLΣ: equivalent load resistance

  The variation in the discharge current of each battery group is caused by the variation in the battery internal electromotive voltage eB and the battery internal resistance RB. That is, the “current-voltage characteristics (IV characteristics)” of each battery group during the discharge operation is determined by the battery internal electromotive voltage eB, the battery internal resistance RB, and the voltage drop due to the discharge current. Due to variations in the voltage eB and the battery internal resistance RB, the IV characteristics of each battery group vary as shown in FIG. 5, and the difference in the IV characteristics of each battery group is expressed as a difference in the discharge current of the battery group. Is called. Hereinafter, the cause of variation in battery characteristics and the electrical causal relationship will be described.

(2-1) Battery Internal Electromotive Voltage eB: Small The battery has a tendency that the battery internal resistance RB increases when the battery internal electromotive voltage eB decreases, and the battery internal resistance RB decreases when the battery internal electromotive voltage eB increases. Therefore, if the battery internal electromotive voltage eB is small, the slope of the IV characteristic increases due to the large battery internal resistance RB, and the discharge current decreases. That is, since all battery group terminal voltages are the same in the battery group connected in parallel, an extreme decrease in the internal electromotive voltage eB reduces the discharge current.
(2-2) Battery Internal Electromotive Voltage eB: Large If the battery internal electromotive voltage eB is large, the slope of the IV characteristic is small and the discharge current is large because the battery internal resistance RB is small. That is, since all battery group terminal voltages are the same in the battery group connected in parallel, an extreme increase in the internal electromotive voltage eB increases the discharge current.

(2-3) Battery Internal Resistance RB: Large If battery internal resistance RB is large, the slope of the IV characteristic increases and the discharge current decreases. That is, since all battery group terminal voltages are the same in the battery group connected in parallel, an extreme increase in RB reduces the discharge current.
(2-4) Battery Internal Resistance RB: Small If the battery internal resistance RB is small, the slope of the IV characteristic is small and the discharge current is large. However, an extreme decrease in RB is considered to be the same phenomenon as the battery internal electromotive voltage eB is apparently reduced due to a short circuit inside the battery (see section 2-1 above). In this case, since all battery group terminal voltages are the same in the battery group connected in parallel, an extreme decrease in eB (internal short circuit) results in a decrease in discharge current.

By the way, according to the method proposed in Patent Documents 1 to 3, since the battery is charged while switching, not only charging time is lengthened, but also noise generation caused by switching becomes a problem.
In addition, while lithium-ion batteries have the advantage of high energy density, "risk of ignition and explosion due to overcharge" has been pointed out, and in addition, "deterioration of battery characteristics due to overdischarge" is reported. Therefore, careful attention and strict monitoring and control are required for charging and discharging, and when charging and discharging multiple battery groups connected in parallel, appropriate measures against deterioration and damage due to characteristic variations are required. Protection is required.
Accordingly, an object of the present invention is to shorten the charging time without generating noise and to enable appropriate battery protection.

In order to solve such a problem, in the invention of claim 1, a plurality of battery groups in which n (natural number of 2 or more) batteries are connected in series are connected in parallel to m (natural number of 2 or more) groups. A battery group, a load including an electric motor, a motor-driven generator for charging the plurality of battery groups and supplying power to the loads, a switch connected in series to each of the battery groups, and the switch A control circuit that performs on / off control and performs charge / discharge control of the plurality of battery groups and control of the prime mover drive generator;
When batch charging of the battery group is performed by the control circuit, an average charging current value is obtained from the charging current setting value or the actual charging current value, and a charging current allowable value prepared in advance is calculated from the charging current average value and the actual battery voltage value. Read the upper and lower limits of the charging current allowable variation range based on the average charging current value with reference to the variation map, compare these with the charging current of each battery group, and apply if the allowable variation range is exceeded. The battery is protected by turning off the switch to stop charging.
In the first aspect of the invention, when the battery group is disconnected by turning off the switch in a constant current charge state, the battery does not increase the charging current of other healthy battery groups as the number of battery groups decreases. The output of the generator can be reduced by an amount corresponding to the decrease in the number of groups, and the burden on the healthy battery group can be reduced (invention of claim 2).

In the invention of claim 3, a load including a plurality of battery groups in which a battery group in which n (natural number of 2 or more) batteries are connected in series is connected in parallel to m (natural number of 2 or more) groups, and an electric motor A prime mover drive generator for charging the plurality of battery groups and supplying power to the load, a switch connected in series to each of the battery groups, and turning on and off the switch to control the plurality of the plurality of battery groups A charge / discharge control of the battery group and a control circuit for controlling the prime mover drive generator,
When performing the collective discharge of the battery group by the control circuit, the discharge current average value is obtained from the actual discharge current value, and the discharge current allowable variation map prepared in advance is referred to from the average discharge current value and the actual battery voltage value. The upper and lower limits of the discharge current allowable variation range based on the average discharge current value are read out, and these are compared with the discharge currents of the individual battery groups. When the allowable variation range is exceeded, an alarm is issued and the corresponding The battery group is separated from the circuit to protect the battery group.
In the invention of claim 3, the battery group can be disconnected from the circuit by manual operation or automatic operation by a switch (invention of claim 4).

  According to the present invention, the charging time is shortened by batch charging a plurality of battery groups connected in parallel by continuous constant-voltage charging or constant-current charging without generating noise, and the individual batteries in the charge / discharge operation When the charge / discharge current exceeds an allowable value due to the variation in the group, it becomes possible to stop the charging or discharging of the corresponding battery group to protect the battery group.

  FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, 1 and 2 are battery groups (B1, Bm) in which a plurality of cells are connected in series, and 3 and 4 are anti-parallel semiconductor elements (Q1, Qm) and diodes (D1, Dm). Switch circuit comprising circuits, 5, 6, 9, 13, 26 are current detectors, 7, 8, 10, 14 are voltage detectors, 11 is a generator motor (DE) for driving the generator, 12 is a generator ( G), 15 is an auxiliary machine (L), 16 is a propulsion motor (M), 17 is a program setting device, 18 is a pulse charge switch (SWP), 19 is a charge switch (SWC), 20 is a floating charge switch (SWF) ), 21 is a voltage setting device (VRV), 22 is a current setting device (VRI), 23 is a charge / discharge control circuit & battery state monitoring device, 24 is a charge control changeover switch (SWvc), 25 is a generator control device, 27 Is the generator field, 28 is the charge / discharge electricity Allowable variation map, 30 alarm, 31 - 34 switches, 35 and 36 are switches (SW1, SWm).

A) Protection operation during charging A-1) First, the case of constant voltage charging operation will be described. In this case, the charge switch SWC19 is switched to the constant voltage side. Thereby, the charge / discharge control circuit & battery state monitoring device 23 switches the charge control changeover switch SW _VC 24 to the voltage side, and generates a generator voltage command from the generator voltage setting unit VRV21 in order to obtain a predetermined total charge current + IBΣ. VGs are output and supplied to the generator control device 25.

The generator control device 25 sets the generator voltage command VGs as a set value, the detection signal VGi of the generator voltage detector VDG14, the detection signal IGi of the generator current detector SHG13, and the generator field current detector SHGF26. The detection signal IGfi is used as a feedback signal, and the generator voltage is controlled by adjusting the current IGf of the generator field GF27.
By this generator voltage control, even if the loads of the auxiliary machine L15, the electric motor M16, etc. fluctuate, it is possible to supply a stable generator voltage VG to the battery group and supply the total charging current + IBΣ.

A-2) Next, the case of constant current charging operation will be described. In this case, the charge switch SWC19 is switched to the constant current side. As a result, the charge / discharge control circuit & battery state monitoring device 23 switches the charge control changeover switch SW _VC 24 to the current side, and outputs the battery current command IBs from the current setting unit VRI22 so as to obtain a predetermined total charge current + IBΣ. To the generator control device 25.

The generator control device 25 uses the battery current command IBs as a set value, the detection signal IBi detected by the battery current detector SHB9, the detection signal VGi detected by the generator voltage detector VDG14, and the generator current detector SHG13. Using the detected signal IGi detected and the detected signal IGfi detected by the generator field current detector SHGF26 as a feedback signal, the current IGf of the field GF27 of the generator is adjusted and the total charging current + IBΣ becomes the battery current command value IBs. The generator is controlled so that
By this generator current control, even if the loads of the auxiliary machine L15, the electric motor M16, etc. fluctuate, a stable total charging current + IBΣ can be supplied from the generator.

4 (a) and 4 (b) showing the operation at the time of charging, + IBΣ is a total charging current supplied from the generator, and + IB1 to + IBm are charging currents of the battery groups B1 to Bm, It shows a state where current variation occurs.
FIG. 2A illustrates the variation in the charging current of the battery groups B1 to Bm connected in parallel as described above on a plane with the charging current IB as the horizontal axis and the battery voltage VBi as the vertical axis. The charging operation states (+ IB1, VBit) to (+ IBm, VBit) of the battery groups B1 to Bm at a certain time are indicated by black circles.

Here, Ime shown in FIG. 2 (a) treats the current command (set) value IBs from the setter 22 or the battery group total charge current IBi detected by the battery current detector SHB9 as the total charge current + IBΣ. Is the average current value (Ime = IBΣ / m) (where IBΣ = IBs or IBΣ = IBi) obtained by dividing by the number m of battery groups by the charge / discharge control circuit & battery state monitoring device 23, and charge / discharge control The circuit & battery state monitoring device 23 gives this average current value Ime to the charge / discharge current allowable variation map 28. Note that the current value treated as the total charging current + IBΣ is the battery group total charging current IBi in the constant voltage charging operation, and may be either the current command value IBs or the battery group total charging current IBi in the constant current charging operation. The battery group total charging current IBi, which is the actual charging current, is more preferable from the viewpoint that the means for obtaining the average current value Ime is unified with the case of the constant voltage charging operation.
IBmx and IBmn in FIG. 2A indicate the upper limit side limit value and the lower limit side limit value of the charge current allowable variation output from the charge / discharge current allowable variation map 28. In FIG. A state in which the charging current + IBm of Bm exceeds the upper limit side limit value IBmx is shown.

In FIG. 1, a charge / discharge current allowable variation map 28 is inputted with the battery voltage VBi together with the above average current value Ime from the charge / discharge control circuit & battery state monitoring device 23, and the variation stored in the map from these values. An upper limit side limit value IBmx and a lower limit side limit value IBmn are obtained and output to the charge / discharge control circuit & battery state monitoring device 23.
The charge current allowable variation map in the charge / discharge current allowable variation map 28 sets an allowable variation range for each charging operation state defined by the average current Ime and the battery voltage VBi of the battery system in which the battery groups B1 to Bm are connected in parallel. This will be described with reference to FIG.

  FIG. 6 is an explanatory diagram of an allowable variation map during the charging operation, in which the horizontal axis is the average current value Ime, the vertical axis is the battery voltage VBi, and the intersection point on the Ime-VBi plane indicated by a black circle. A to F indicate charging operation states of the battery system corresponding to (Ime = ImeA, VBi = VBiA) to (Ime = ImeF, VBi = VBiF), respectively, and an allowable variation range for each such intersection. Data is stored. If the average current Ime and the battery voltage VBi input to the charge / discharge current allowable variation map 28 are, for example, Ime = ImeA and VBi = VBiA, respectively, it is determined that the charging operation state is at the intersection A, and the corresponding allowable variation. The range data is read and output as a variation upper limit value IBmx (= IBmxA) and a lower limit value IBmn (= IBmnA). As the allowable variation range data stored for each intersection, the limit values IBmx and IBmn as described above may be stored, and the ratio of the allowable variation range to the average current value Ime, that is, the upper limit side The coefficient Kmx (%) and the lower limit coefficient Kmn (%) are stored for each intersection, and the limit value IBmx = (1 + Kmx) using the coefficients Kmx and Kmn read corresponding to the charging operation state of the battery system. ) * Ime, IBmn (1-Kmn) * Ime may be calculated.

  Next, an example of how to set the allowable variation range according to the charging operation state will be described with reference to FIG. Zones <1> to <3> represented by broken-line ellipses in FIG. 6 are in an initial charging state, an intermediate charging state, and an end of charging (near full charge) where the battery internal electromotive voltage eB is low and the charging current is large. For example, the allowable variation range of ± 10 to 15% at the intersections A to B in the zone <1>, and the allowable variation range of ± 5 to 10% at the intersections C to D in the zone <2>. The allowable variation range of ± 5% is set at the intersections E to F in the zone <3>. The allowable variation range is widened at the beginning and middle of charging, and the allowable variation range at the end of charging (near full charge). It is narrowed so that battery protection is strictly controlled and checked. In FIG. 6, the difference in the allowable variation range for each zone as described above is expressed by the difference in the size of the black circles at the intersections A to F.

Further, in the above description with reference to FIG. 6, an example in which the allowable variation range is set in three stages corresponding to the zones <1> to <3> has been shown. The variation range may be set by changing more finely according to the charging operation state. In addition, the specific setting value of the allowable variation range as described above should be determined based on the management criteria determined in accordance with the structure, type, capacity, scale, usage, etc. of the target battery. .
Further, in a charging operation state in which the battery voltage is low as shown by zone <4> and the charging current is lowered for some reason, the allowable variation range is not narrowed even if the charging current is small. The charging operation state in which the charging current is increased even though the battery voltage is high, as indicated by the zone <5>, is not the normal charging operation state, so the charging operation state as in the zone <5> is determined. In such a case, a warning such as “abnormal” or “prohibited” or measures such as charge reduction or stop may be taken.

  As described above, the current limiting values IBmx and IBmn read from the charge / discharge current allowable variation map 28 and the charge currents + IB1 to + IBm detected by the current detectors SH1 to SHm provided in each battery group in FIG. If the current detection values + IB1 to + IBm exceed the allowable variation range set by the limit values IBmx and IBmn when compared in the circuit & battery state monitoring device 23, the charge / discharge control circuit & battery state monitoring device 23 corresponds to the corresponding battery group. An OFF command Q1dv to Qmdv is issued to the semiconductor elements Q1 to Qm to stop charging, protect the battery and continue to charge the healthy battery group to ensure safe operation of the system.

In the constant current charging mode, when the battery group is disconnected by the above-described battery protection operation and the number of battery groups decreases, if left as it is, the charging current per group of healthy battery groups that continue charging is not preferable. Therefore, when the number of stopped battery groups is nx, the charge / discharge control circuit & battery state monitoring device 23 sets the generator current command value IBs to IBsx = IBΣ × (m−nx) / m (where m: all The number of battery groups, nx: the number of stopped battery groups), and the increase in charging current of the healthy battery group is suppressed.
Further, as described above, in the constant current charging mode, when the battery group of the nx group out of the total battery group number m is separated beyond the allowable variation range, the group of the healthy battery group of the (m−nx) group In order to suppress the increase in charging current, the generator current command value is changed from IBs = IBΣ to IBsx = IBΣ × (m−nx) / m, and control is performed to reduce the generator output. During the settling time of the decrease control, the charging current IB per group of healthy battery groups increases transiently.

  On the other hand, when the average current value Ime for obtaining the upper limit value IBmx and the lower limit value IBmn of the allowable variation range is obtained from the current command value IBs, the average current value Ime is the generator current command value. Ime = IBsx / (m−nx) = {IBΣ × (m−nx) / m} / (m−nx) = IBΣ / m, and the average current before the generator current command value is changed Since the value Ime = IBΣ / m does not change, the upper limit value IBmx and the lower limit value IBmn do not change before and after the generator current command value is changed. For this reason, only the charging current IB per group of healthy battery groups transiently increases during the settling time of the generator output reduction control when the generator current command value is changed. Therefore, the transient increase amount of the charging current IB is increased. If it is larger, the allowable variation range may be exceeded and a variation abnormality may be erroneously detected.

  Further, when the average current value Ime is obtained from the battery group total charge current IBi that is the actual charge current, the healthy battery group corresponding to the transient increase in the charging current IB per group of the healthy batteries as described above. The actual average current value at the time also increases transiently. However, since there is a processing time delay for calculating the average current value Ime and obtaining the upper limit value IBmx and the lower limit value IBmn, the upper limit value IBmx And the lower limit side limit value IBmn does not follow the transient increase of the charging current IB per group of healthy batteries as it is, so if the transient increase of the charging current IB is large, the allowable variation range is exceeded and the variation is abnormal. May be erroneously detected. In order to prevent such erroneous detection of variation abnormality, it is preferable to mask the variation abnormality detection process for a predetermined time by a timer when the abnormal battery group is disconnected.

  Assuming that an internal short circuit has occurred in a series cell of a certain battery group, such a state reduces the series electromotive voltage eB of that battery group, and the apparent charging current compared to other healthy battery groups. The battery group is protected if the semiconductor elements connected in series are turned off by the detection signal of the abnormal state. In addition, since the generator voltage and the current inflow from other healthy battery groups are blocked by the diodes D1 to Dm connected in antiparallel with the corresponding semiconductor elements, the system can be operated without affecting other healthy circuits. Safe driving continues.

In the case of the constant voltage charging operation, the temperature coefficient of the battery internal resistance in a general battery is negative. Therefore, even if the applied voltage VB is constant, IB = (VB−eB) / RB (where IB : Charging current, eB: battery internal electromotive voltage, RB: battery internal resistance), the battery internal resistance RB of the denominator decreases and the charging current IB increases due to the temperature rise, and the battery internal loss IB increases when the charging current IB increases. ² * The battery temperature rises due to the increase in RB, and if the battery temperature rises, the battery internal resistance RB may decrease, which may cause a thermal runaway condition, but the battery temperature increases and the charging current IB increases. Then, when the allowable variation range is exceeded, by turning off the switch corresponding to the battery and stopping the charging, it is possible to prevent the occurrence of a failure due to the battery temperature rise.
Note that the charging pattern for batch charging of a plurality of battery groups in the battery protection method of the present invention is not limited to a charging pattern in which only constant voltage charging or constant current charging is performed from the initial charging stage to the final charging period. The charging pattern may be such that the charging mode is switched between constant voltage charging and constant current charging or the set voltage value or set current value is changed.

B) Protective operation at the time of discharge In FIG. 5 showing the operation at the time of discharge (current-voltage characteristics), −IBΣ is the total discharge current obtained by summing the discharge currents from the battery groups connected in parallel, and − IB1 to -IBm are discharge currents of the battery groups B1 to Bm, and current variations are caused by variations in the current-voltage characteristics (IV characteristics) of the battery groups.
FIG. 2B illustrates the variation of the discharge currents of the battery groups B1 to Bm connected in parallel as described above on a plane with the discharge current IB as the horizontal axis and the battery voltage VBi as the vertical axis. The discharge operation states (−IB1, VBit) to (−IBm, VBit) of the battery groups B1 to Bm at a certain time are indicated by black circles.

Here, the current Ime shown in FIG. 2B is an average value of the discharge current, and the current detector SHB9.
The value obtained by dividing the signal IBi detected in step IBΣ by IBΣ by the number of battery groups m, that is, the value obtained by the calculation of Ime = IBΣ (= IBi) / m in the charge / discharge control circuit & battery state monitoring device 23 The charge / discharge control circuit & battery state monitoring device 23 gives this average current value Ime to the charge / discharge current allowable variation map 28.
Further, IBmx and IBmn in FIG. 2B indicate the upper limit side limit value and the lower limit side limit value of the discharge current allowable variation output from the charge / discharge current allowable variation map 28, and in FIG. The state where the discharge current -IBm of the battery group Bm exceeds IBmx is shown.
In FIG. 1, as in the case of the charging operation, the charge / discharge current allowable variation map 28 is inputted with the battery voltage VBi from the charge / discharge control circuit & battery state monitoring device 23 together with the above average current value Ime. The variation upper limit side limit value IBmx and lower limit side limit value IBmn stored in the map are obtained and output to the charge / discharge control circuit & battery state monitoring device 23.

The discharge current allowable variation map in the charge / discharge current allowable variation map 28 is the average current Ime of the battery system in which the battery groups B1 to Bm are connected in parallel as in the case of the charge current allowable variation map described with reference to FIG. The allowable variation range is set for each discharge operation state defined by the battery voltage VBi, which will be described with reference to FIG.
FIG. 7 is an explanatory diagram of an allowable variation map at the time of discharging operation, in which the horizontal axis is the average current value Ime, the vertical axis is the battery voltage VBi, and the zone <1> expressed by a dashed ellipse. And <2> indicate a region where the battery voltage VBi is high and the remaining battery amount is large, and a region where the battery voltage VBi is low and the remaining battery amount is small, respectively. Regardless, the allowable variation range is ± 10 to 15%, and battery management is performed within a narrow allowable variation range of ± 5 to 10% in the zone <2>. Although it is considered that variation management at the time of discharge does not have to be so strict, in the discharge termination region where the battery voltage is low, the discharge current is as shown in the above example from the viewpoint of preventing overdischarge caused by battery variation. It is considered better to narrow the permissible variation range.

  Although not shown in FIG. 7, in the discharge current allowable variation map, as in the case of the charge current allowable variation map described with reference to FIG. If the battery voltage VBi is, for example, Ime = ImeG and VBi = VBiG, respectively, the allowable variation range data at the corresponding intersection point G (ImeG, VBiG) on the Ime-VBi plane is read, and the upper limit side of the variation The limit value IBmx (= IBmxG) and the lower limit limit value IBmn (= IBmnG) are output.

  As described above, the current limit values IBmx and IBmn read from the charge current allowable variation map 28 and the discharge currents -IB1 to -IBm detected by the current detectors SH1 to SHm provided in each battery group in FIG. 1 are charged and discharged. When the current detection values -IB1 to -IBm exceed the allowable variation range set by the limit values IBmx and IBmn when compared in the control circuit & battery state monitoring device 23, the charge / discharge control circuit & battery state monitoring device 23 And an alarm is generated from the alarm device 30.

Here, 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 group occurs, an alarm is first given. With only output, the abnormal battery group can be separated by manual operation based on the judgment after fully grasping the situation of the entire system including the battery, generator and load. It is preferable to keep it. For this reason, switches SW1 to SWm (35, 36) are provided, and the switches can be opened manually to disconnect the battery group.
As such switches SW1 to SWm for separating the battery group during the discharge operation, a mechanical contact type switch with a small current loss is suitable in consideration of a large current during the discharge operation, but a semiconductor switch is also applicable. Is possible. As a mechanical contact type switch applied to the switches SW1 to SWm, for example, a switch such as a load switch or a circuit breaker may be used. This mechanical contact type switch is a controllable switch with a remote operation function by electric power, etc., and in addition to manual operation on the switch, remote manual operation while monitoring the operating status of the entire system from the centralized monitoring controller You may enable it to operate.

Next, FIG. 8 shows an example in which the battery group disconnecting switches SW1 to SWm at the time of discharging are configured by semiconductor switches. The circuit of FIG. 8 includes a switch SW1 (in the series connection circuit portion of the semiconductor switch Q3 and the switch SW1 (35) composed of the semiconductor element Q1 and the antiparallel diode D1 corresponding to the battery group B1 shown in FIG. 35) is composed of a semiconductor switch circuit for discharge formed by connecting in parallel a semiconductor element QR1 and a diode DR1 having opposite polarities to the semiconductor element Q1 and the diode D1, respectively, and a charge / discharge control circuit & battery state monitoring device The semiconductor device QR1 is turned OFF by the OFF command QR1dv from 23, and the discharge from the corresponding battery group B1 is stopped. And also about battery group B2-Bm, SW2-SWm which consists of a semiconductor switch circuit for discharge is provided similarly to battery group B1.
Further, depending on the configuration of the system including the battery, the generator, and the load, when a discharge current variation abnormality of a certain battery group occurs, a controllable switch, that is, a mechanical contact type switch having a remote operation function as described above or The battery group may be automatically disconnected by using a discharging semiconductor switch circuit as shown in FIG. 8, and the disconnect control circuit is set to manual / automatic switching type, depending on the operating condition of the system. It is better to be able to select the separation control mode.

  Assuming that an internal short circuit has occurred in a series cell of a certain battery group, such a state reduces the series electromotive voltage eB of that battery group, and apparent discharge current compared to other healthy battery groups. Since the battery is in an abnormal state that decreases, an alarm is issued by a detection signal of this abnormal state. And according to the situation judgment based on this warning, it can open a corresponding switch among switches SW1-SWm by manual operation, and can isolate | separate a corresponding battery group. In addition, as described above, depending on the configuration of the system including the battery, the generator, and the load, the corresponding battery group can be disconnected automatically by using the controllable switches SW1 to SWm. In both cases of manual disconnection and automatic disconnection, the generator voltage and the current inflow from other healthy battery groups are blocked, so that safe operation of the system continues without affecting other healthy circuits. Is done.

In the case of disconnecting the abnormal battery group by the discharging semiconductor switch circuit shown in FIG. 8, the generators are generated by the diodes D1 to Dm and DR1 to DRm connected in reverse parallel to the semiconductor elements Q1 to Qm and QR1 to QRm, respectively. Current flow from voltage and other healthy battery groups is blocked.
Further, the charge / discharge current allowable variation map 28 in the configuration of FIG. 1 has both the function of the charge current allowable variation map and the function of the discharge current allowable variation map. When only one of the battery group protections at the time of discharging is performed, a map having only a function of either a charge current allowable variation map or a discharge current allowable variation map can be obtained.

Configuration diagram showing an embodiment of the present invention Explanation of variation range of charge and discharge current in this invention Circuit diagram showing charge / discharge operation circuit Illustration of constant voltage charge operation and constant current charge operation Characteristic diagram showing current-voltage characteristics during discharge Explanatory diagram of allowable variation map during charging operation Explanatory diagram of allowable variation map during discharge operation Explanatory drawing of semiconductor switch circuit for discharge

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,2 ... Battery group (B1, Bm), 3, 4 ... Switch circuit, 5, 6, 9, 13, 26 ... Current detector, 7, 8, 10, 14 ... Voltage detector, 11 ... Driving motor (DE), 12 ... Generator (G), 15 ... Auxiliary machine (L), 16 ... Propulsion motor (M), 17 ... Program setting device, 18 ... Pulse charge switch (SWP), 19 ... Charge switch (SWC) ), 20 ... Floating charge switch (SWF), 21 ... Voltage setter (VRV), 22 ... Current setter (VRI), 23 ... Charge / discharge control circuit & battery state monitoring device, 24 ... Charge control changeover switch (SWvc) , 25 ... Generator control device, 27 ... Generator field, 28 ... Charge / discharge current allowable variation map, 30 ... Alarm, 31-34 ... Switch, 35, 36 ... Switch (SW1, SWm).

Claims (4)

a plurality of battery groups in which n (natural number of 2 or more) batteries connected in series are connected in parallel to m (natural number of 2 or more) groups, a load including an electric motor, and the plurality of battery groups A motor-driven generator for charging the battery and supplying power to the load, a switch connected in series to each of the battery groups, and on / off control of the switches for charge / discharge control of the plurality of battery groups And a control circuit for controlling the prime mover drive generator,
When batch charging of the battery group is performed by the control circuit, an average charging current value is obtained from the charging current setting value or the actual charging current value, and a charging current allowable value prepared in advance is calculated from the charging current average value and the actual battery voltage value. Read the upper and lower limits of the charging current allowable variation range based on the average charging current value with reference to the variation map, compare these with the charging current of each battery group, and apply if the allowable variation range is exceeded. A battery protection system characterized in that the switch is turned off to stop charging to protect the battery group.   When the battery group is disconnected by turning off the switch in the state of constant current charging, the amount corresponding to the decrease in the number of battery groups is prevented so that the charging current of other healthy battery groups does not increase with the decrease in the number of battery groups. The battery protection system according to claim 1, wherein the output of the generator is reduced to reduce a burden on a healthy battery group. a plurality of battery groups in which n (natural number of 2 or more) batteries connected in series are connected in parallel to m (natural number of 2 or more) groups, a load including an electric motor, and the plurality of battery groups A motor-driven generator for charging the battery and supplying power to the load, a switch connected in series to each of the battery groups, and on / off control of the switches for charge / discharge control of the plurality of battery groups And a control circuit for controlling the prime mover drive generator,
When performing the collective discharge of the battery group by the control circuit, the discharge current average value is obtained from the actual discharge current value, and the discharge current allowable variation map prepared in advance is referred to from the average discharge current value and the actual battery voltage value. The upper and lower limits of the discharge current allowable variation range based on the average discharge current value are read out, and these are compared with the discharge currents of the individual battery groups. When the allowable variation range is exceeded, an alarm is issued and the corresponding A battery protection method comprising protecting a battery group by separating the battery group from a circuit.   The battery protection system according to claim 3, wherein the battery group is separated from the circuit by manual operation or automatic operation using a switch.

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