JP2000354333A - Power unit and battery unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a power unit to supply electric power from remaining battery cells even when the characteristics of one of serially connected battery cells deteriorates, by providing a first switch circuit which stops flowing of a discharge current and a second switch circuit which makes a flow-in current to by-pass. SOLUTION: Circuits S1 and S2 constitute a first switch circuit which stops flow-in of a charging current and flow-out of a discharging current. In each battery unit 3A-3N, a switch circuit S3 composed of a parallel circuit of a field-effect transistor 6A and a diode 6B is arranged in parallel with a serial circuit of a battery cell 1 and the first switch circuit, so that the switch circuit S3 may constitute a second switch circuit which makes the current flowing in a battery cell 2 by-pass. Here, the diode 6B of the second switch circuit S3 is arranged in a polarity that does not inhibit discharging currents from other serially connected battery cells.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device and a battery unit, and can be applied to, for example, a case where various devices are driven by a high-voltage power supply by connecting cells of a lithium ion battery in series. The present invention
When one characteristic of a series-connected battery cell is deteriorated by arranging a switch circuit for preventing overdischarge and overcharge of the battery cell and a switch circuit for bypassing a current flowing into the battery cell in each battery cell. However, the power can be supplied from the remaining battery cells.

[0002]

2. Description of the Related Art Conventionally, lithium ion batteries have been used for relatively low-voltage power supplies such as portable telephones and personal computers.

In such a battery, if necessary, a battery cell as a basic structural unit is connected in series to secure a desired voltage, and over-discharge of a plurality of battery cells connected in series is performed. , Overcharge is managed collectively.

[0004]

However, in such a relatively low-voltage power supply, if the characteristics of even one of the series-connected battery cells deteriorates due to the small number of stages connected in series, the overall As a result, the power supply voltage greatly decreases, which makes it practically impossible to supply power and drive the device. As a result, in such a relatively low-voltage power supply, a plurality of battery cells connected in series can be collectively managed, and the power can be supplied simply and stably.

[0005] When this type of battery is used for driving a passenger car, for example, it is conceivable to construct a relatively high-voltage power supply by connecting tens of cells in series. In such a case, even if one of the battery cells connected in series deteriorates due to an increase in the number of stages connected in series, the remaining battery cells secure sufficient power supply for driving the device. can do.

[0006] Even in such a case, if the overdischarge and overcharge of these tens of cells are managed collectively as in the past, it is possible to supply a sufficient power as a whole. In addition, there is a problem that it becomes difficult to supply electric power due to characteristic deterioration of one battery cell.

The present invention has been made in view of the above points, and even when one characteristic of a battery cell connected in series deteriorates, a power supply device capable of supplying power from the remaining battery cells, this power supply It is intended to propose a battery unit applied to the device.

[0008]

According to the first aspect of the present invention, in order to solve the above-mentioned problem, the present invention is applied to a power supply device, and each battery cell stops the inflow of the charging current and / or the outflow of the discharging current. A first switch circuit;
A second switch circuit for bypassing the inflowing current.

In the invention according to claim 4, the invention is applied to a battery unit which is used in series with another battery unit, so that a charging current flows into a battery cell and / or a discharging current flows from a battery cell. A first switch circuit for stopping the outflow and a second switch circuit for bypassing the current flowing into the battery cell are provided.

According to the first aspect of the present invention, each battery cell stops the inflow of the charging current and / or the outflow of the discharging current, and the second switch circuit for bypassing the inflowing current. With respect to the battery cell in which the abnormality is detected, the first
By setting the switch circuit in the off state and setting the second switch circuit in the on state, only the other battery cells can be charged and discharged by separating from the other battery cells. Power can be supplied by the cell.

According to the fourth aspect of the present invention, the battery unit connected and used in series with another battery unit can prevent the charging current from flowing into the battery cell and / or the discharging current from the battery cell from flowing out. By providing a first switch circuit for stopping and a second switch circuit for bypassing a current flowing into the battery cell, the first switch circuit is set to an OFF state upon detection of an abnormality, and the second switch circuit is set. By setting the circuit to the ON state, the battery cells of this battery unit are separated from the battery cells of other battery units, and only the other battery units can be charged and discharged.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment FIG. 1 is a block diagram showing a power supply device according to a first embodiment of the present invention. The power supply device 1 includes battery units 3A to 3A each holding a battery cell 2.
3N connected in series, the battery units 3A to 3N are charged by a charging power supply supplied from the charging circuit 11, and a relatively high voltage power supply is generated from the battery units 3A to 3N to produce desired equipment. To supply.

Here, the battery units 3A to 3N are
The power supply device 1 has the same configuration and is exchangeable.
The battery units 3A to 3N include a field effect transistor 4A and a diode 4 in series with the battery cell 2.
A switch circuit S1 for stopping discharging of the battery cell 2 by a parallel circuit of B, and a switch for stopping charging of the battery cell 2 by a parallel circuit of a field effect transistor 5A and a diode 5B having polarities opposite to the switching circuit S1. The circuit S2 is connected in series. Thus, these switch circuits S1 and S2 constitute a first switch circuit for stopping the inflow of the charging current and the outflow of the discharging current.

The battery units 3A to 3N include a field effect transistor 6A and a diode 6B in parallel with a series circuit of the battery cell 2 and the first switch circuit.
And a switch circuit S3 formed by a parallel circuit of the above is arranged, and this switch circuit S3 constitutes a second switch circuit for bypassing the current flowing into the battery cell 2. Here, the diode 6B of the switch circuit S3 is arranged to have a polarity that does not prevent the discharge current of the other battery cells connected in series.

In the battery units 3A to 3N,
The control circuit 8 controls the switching circuits S1 to S3 based on a control signal output from a control circuit 12 that controls the operation of the charging circuit 11, and overdischarge and overcharge obtained by detecting the voltage across the battery cell 2. Control.

FIG. 2 is a flowchart showing the control processing procedure of the control circuit 8. In the control circuit 8, the operation is started by a predetermined driving power source, and the process proceeds from step SP1 to step SP2.

Here, the driving power supply of the control circuit 8 is a charging power supply supplied from the charging circuit 11, a power supply supplied to the apparatus from the power supply device 1, a power supply for each battery unit and a battery cell, and a separate power supply. For example, a combination of these can be applied.

In step SP2, the control circuit 8 determines whether or not the charging of the battery cell 2 has been started based on the control signal output from the control circuit 12, and if a positive result is obtained here, the control proceeds to step SP2. Move to SP3. In step SP3, the control circuit 8 switches the switch circuits S1 and S2 to the ON state and switches the switch circuit S3 to the OFF state, so that the battery cell 2 can be charged by the charging current supplied from the charging circuit 11. To

Further, when the control circuit 8 switches the switch circuits S1 to S3 in this way, in this case, the control circuit 8 notifies the control circuit 12 that charging has been started normally. Subsequently, the control circuit 8 proceeds to step SP4, where it determines whether or not overcharging is performed based on the potentials at both ends of the battery cell 2.

If a negative result is obtained here, the control circuit 8
Moves to step SP5, and determines whether or not the charging is completed based on the control signal output from the control circuit 12. If the charging is continued, the process returns to step SP4. Thus, when the charging is started by the charging circuit 11, the control circuit 8 switches the switching circuit S so that the battery cell 2 can be charged.
After switching from 1 to S3, steps SP4-SP5-S
When the process procedure of P4 is repeated and the battery cell 2 is charged until the battery is fully charged, a positive result is obtained in step SP4, and the process proceeds from step SP4 to step SP6.

Here, after notifying the control circuit 12 of the completion of charging, the control circuit 8 switches the switch circuit S1 to the off state so that the discharge current does not flow out of the battery cell 2. Subsequently, the control circuit 8 proceeds to step SP7 after the elapse of the predetermined time Δt, sets the switch circuit S3 to the ON state, and forms a bypass for the charging current supplied from the charging circuit 11.

Subsequently, the control circuit 8 proceeds to step SP8 after a lapse of a predetermined time Δt, and sets the switch circuit S2 to the off state. Thereby, the control circuit 8 stops the flow of the charging current to the battery cell 2 without stopping the supply of the charging current to the other battery units, and the step S
Return to P2.

On the other hand, if it is determined in step SP2 that the charging state has not been set by the control signal from the control circuit 12, the control circuit 8 proceeds to step SP2.
From step 2 to step SP9, where the switch circuit S1
And S2 are turned on, and the switch circuit S3 is turned off, so that the discharge current output from the battery cell 2 can be output to a desired device.

Subsequently, the control circuit 8 proceeds to step SP10, in which it determines whether or not the battery cell 2 is overdischarged based on the potential at both ends thereof. If a negative result is obtained here, the control circuit 8 proceeds to step SP11, determines whether or not charging has been started by the control signal from the control circuit 12, and returns a step SP10 if a negative result is obtained here. Thereby, the control circuit 8 switches the switch circuits S1 to S3 so that the battery cell 2 can be discharged when it is not charged, and then repeats the processing procedure of steps SP10-SP11-SP10 until the battery cell 2 becomes difficult to discharge. When 2 discharges, a positive result is obtained in step SP10, and the process moves from step SP10 to step SP12.

In this case, the control circuit 8 executes this step SP
At 12, the switching circuits S1 and S2 are turned off, thereby stopping the discharge current from the battery cell 2 and discharging the discharge current from another battery unit to the diode 6 disposed in the switch circuit S3.
B bypasses. Subsequently, the control circuit 8 proceeds to step SP13 after the elapse of the predetermined time Δt, sets the switch circuit S3 to the ON state, and switches the setting of the switch circuit S3 so as to avoid a voltage drop due to the diode 6B. It returns to step SP2.

Accordingly, the control circuit 8 determines that the battery cells 2 are difficult to charge and discharge at a point earlier than other battery units due to variations among the battery cells arranged in the battery units, deterioration of the characteristics of the battery cells, and the like. , The charging and discharging of the battery cell 2 are stopped, and the charging current and the discharging current flowing from the other battery cells are bypassed so that the charging and discharging of the other battery cells are not hindered.

In the control circuit 8, before the battery cell 2 becomes difficult to charge or discharge as described above, the charging is stopped by the notification from the control circuit 12, and the charging is started. When an affirmative result is obtained in SP5 and step SP10, the process directly proceeds from step SP5 to step SP9 and from step SP10 to step SPSP4, and executes the processes during discharging and charging, respectively.

The charging circuit 11 supplies charging power to the battery units 3A to 3N connected in series. The charging circuit 11 controls the power supply voltage of the charging power supply
Thus, even if the switch circuit S3 is held in the ON state in any one of the battery units, each battery cell is charged with a constant charging voltage. .

The control circuit 12 is a control circuit for controlling the operation of the entire power supply device 1. When the supply of charging power from the charging circuit 11 is started, the signal level of a control signal output to each battery unit is controlled. To notify each control circuit 8 of the start of charging. Further, when the charging is normally started by the notification from the control circuit 8 of the battery unit, the control circuit 12 raises the voltage of the charging power supply in response to the notification. When the full charge is notified from the control circuit 8 of any one of the battery units, the voltage of the charging power supply output from the charging circuit 11 falls in response to the notification.

(2) Operation of Embodiment In the above configuration, in the power supply device 1, when the battery units 3A to 3N are set, these battery units 3A to 3N are connected in series. When connected to the power supply, the charging circuit 11 starts supplying charging power to the series circuit of the battery units 3A to 3N.

In this case, in the battery unit which has discharged to the point where it is difficult to discharge, under the control of the control circuit 8, the switch circuit S connected in series to the battery cell 2 is controlled.
1 and S2 are set to the off state, and the switch circuit S3 arranged in parallel with the battery cell 2 is set to the on state. Therefore, any series circuit of the battery units 3A to 3N is not yet used. This means that only the battery cells 2 having a dischargeable capacity are set to be connected in series.

In the power supply device 1, the supply of the charging current to the series circuit of these battery units 3 A to 3 N is started by the low charging voltage under the control of the control circuit 12. The control circuit 8 of each of the battery units 3A to 3N is notified. With this notification, in the power supply device 1, the battery cells 2 that have been discharged to the point where discharge is difficult are switched on and the switch circuits S3 and S2 are switched on and the switch circuit S3 is switched off and switched to a chargeable connection. , All the battery cells 2 of the battery units 3A to 3N are connected in series. In addition, these switch circuits S
The switching of 1 to S3 is notified to the control circuit 12, and by the control of the control circuit 12 based on this notification, the charging voltage supplied to the battery units 3A to 3N is switched,
Supply of the charging current is started by the charging voltage corresponding to the series circuit of all the battery cells 2.

When charging is started in such a manner, in any one of the battery cells 2 due to variation in the characteristics of the battery cells 2 and further deterioration of the characteristics of the battery cells 2, the other battery cells 2 Despite not being fully charged, it is fully charged. In this case, if the supply of the charging current to the battery cell 2 is continued, the battery cell 2 may be damaged.
In this case, overcharging is detected in the corresponding control circuit 8, and the switch circuits S1, S3, S2 are sequentially switched to the off state, the on state, and the off state.

As a result, the charging current supplied to the overcharged battery cell 2 is bypassed by the switch circuit S3 and supplied to the other battery cell 2, so that the other battery cell 2 is continuously charged. It becomes possible.

At this time, the switch circuit S1 for stopping the discharge of the battery cell 2 is first switched to the off state, so that the battery cell 2 and the switch circuit S1,
By allowing the charging current to flow continuously through the switch circuit S2, it is possible to cut off the discharge path that short-circuits both ends of the battery cell 2, and thereafter switches the switch circuit S3
Can be turned on to form a bypass for the battery cell 2. This allows the power supply device 1 to stop charging only fully charged battery cells without interrupting charging of other battery cells 2.

Then, by switching the switch circuit S2 to the off state, the charging current shunted to the battery cell 2 can be completely cut off, and the charging of the battery cell 2 is completely stopped. Can be.

When the discharge current is bypassed in this manner, the control circuit 8 of the corresponding battery unit notifies the control circuit 12 of the switching of the switch circuits S1 to S3. The voltage is reduced.

Thus, in the power supply device 1, all the batteries are fully charged even if the characteristics of a large number of battery cells connected in series vary, or even if the characteristics of any of the battery cells deteriorate. can do. Therefore, even when one of the characteristics of the battery cells connected in series is deteriorated, it is possible to satisfy a precondition that power can be supplied from the remaining battery cells.

In the power supply device 1, when the supply of the charging current from the charging circuit 11 is stopped, the signal level of the control signal output from the control circuit 12 is switched, whereby each of the battery units 3A to 3N is switched. The switch circuits S1 and S2 are turned on, the switch circuit S3 is turned off, and all the battery cells 2 are connected in series.

When the charging of the battery cell 2 is stopped halfway, the battery cell 2 that has not been fully charged is
, The switch circuits S1 and S2 are turned on,
Since the switch circuit S3 is kept in the off state, in this case, the switch circuits S1 to S3 are switched to the dischargeable states only for the battery cells 2 that have been charged up to the full charge.

When the supply of power to the load is started by operating the power switch arranged on the load side in the state of being connected in series as described above, the power supply device 1
In, the terminal voltage of each battery cell 2 gradually decreases. In this case as well, due to the variation in the characteristics of the battery cells 2 and the deterioration of the characteristics of the battery cells 2, even if one of the battery cells 2 can discharge the other battery cells 2. Further discharge becomes difficult.

In this case, in this battery cell 2, overdischarge is detected by the control circuit 8, and the switch circuits S1 and S2 are switched on to stop the discharge, and the diode 6 arranged in the switch circuit S3 is switched off.
A bypass path is formed for the current flowing into the battery cell 2 via B. After that, by switching the switch circuit S3 to the ON state, a bypass path is set so as to avoid the voltage drop due to the diode 6B.

As a result, in the power supply device 1, even if one battery cell becomes difficult to use due to variations in the characteristics of the battery cells and further deterioration of the characteristics, the power of the power supply device is higher than that of the other battery cells. Supply can be continued.

In this way, in the case where a large number of battery cells are connected in series to supply power at a high voltage in this manner, even if the voltage drops by one battery cell, the fluctuation of the power supply voltage is practically used. In this case, the load can be kept sufficiently small, so that the load can be driven by continuously supplying power from the other battery cells to the load.

Thus, in this embodiment, even if one battery cell becomes difficult to use, it is possible to continue supplying power to the load from another battery cell. Since all the battery cells can be fully charged, for example, when the characteristics of one battery cell 2 deteriorate, only the corresponding battery unit is replaced without replacing all the battery units. Can be maintained, thereby improving the maintainability.

(3) Effects of the Embodiment According to the above configuration, a switch circuit for preventing overdischarge and overcharge of a battery cell and a switch circuit for bypassing a current flowing into the battery cell are provided in each battery cell. By arranging, even if one characteristic of the battery cells connected in series deteriorates, power can be supplied from the remaining battery cells.

(4) Other Embodiments In the above-described embodiment, the case where the switch circuits S1 and S2 are switched to the off state at the time of overdischarge has been described. However, the present invention is not limited to this. May be switched to the off state only by the switch circuit S2 in which a diode is arranged with a polarity that blocks the current.

In the above embodiment, the case where all the battery cells are charged together has been described.
The present invention is not limited to this, and may be individually charged at the time of charging, or may be charged for each of a plurality of blocks. In this case, a case may be considered in which a switch circuit is separately arranged to disconnect the connection of each battery cell and charge by an individual charging circuit.

In the above-described embodiment, the case where the control circuits 8 directly control the on / off of the switch circuits S1 to S3 by detecting overcharge and overdischarge based on the control signal output from the control circuit 12, respectively. As described above, the present invention is not limited to this. For example, only the switch circuit S1 is turned on / off by a control circuit by overdischarging or overcharging.
The on / off operation may be performed based on the potential difference between both ends of the switch circuit S1 that changes by the on / off control of the switch circuit 1. With this configuration, the state of one switch circuit can be changed to change the state of the subsequent switch circuit, so that the switching processing of the switch circuits can be made more reliable.

In the above embodiment, the control circuit 8 is controlled based on the control signal output from the control circuit 12.
Has been described, the present invention is not limited to this. For example, both ends of the switch circuit S1, S2, or S3 that is set to the OFF state by determining the polarity of the current flowing through the battery cell The charging / discharging process may be switched according to the potential difference.

In the above-described embodiment, the case where the battery is charged at a constant voltage when viewed from each battery cell has been described. However, the present invention is not limited to this. It can be widely applied to charging by various methods such as charging by supply.

[0053]

As described above, according to the present invention, a switch circuit for preventing overdischarge and overcharge of a battery cell and a switch circuit for bypassing a current flowing into the battery cell are arranged in each battery cell. Accordingly, it is possible to obtain a power supply device capable of supplying power to the remaining battery cells even when one characteristic of the battery cells connected in series is deteriorated, and a battery unit applied to such a power supply device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a power supply device according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of a control circuit in the power supply device of FIG. 1;

[Explanation of symbols]

1. Power supply device 2. Battery cell 3A to 3N
... Battery unit, 8, 12 ... Control circuit, 11 ...
... Charging circuit, S1 to S3 ... Switch circuit

Continuation of the front page F term (reference) 5G003 AA01 BA03 CA11 CC04 DA07 DA13 GA01 GC05 5H030 AA03 AA10 AS08 AS11 AS14 BB01 DD08 FF41

Claims (4)

[Claims] 1. A power supply device for connecting a plurality of battery cells in series to charge the battery cells and / or supply power of the battery cells to a desired load, wherein each of the battery cells has a charge current And / or a first switch circuit for stopping the outflow of the discharge current, and a second switch circuit for bypassing the inflow current. 2. The switch circuit according to claim 1, wherein said first switch circuit is a switch circuit for discharging current which stops flowing out of said battery cell, and a switch circuit for charging current which stops flowing of charging current into said battery cell. The power supply device has a control circuit that controls the operation of the first and second switch circuits, and the control circuit detects overcharge of the battery cell when charging the battery cell Switching the discharge current switch circuit to an off state, then switching the second switch circuit to an on state, and subsequently switching the charge current switch circuit to an on state. 2. The power supply device according to 1. 3. The second switch circuit includes a diode that bypasses a discharge current of another battery cell. The power supply device includes a control circuit that controls an operation of the first and second switch circuits. The control circuit, when discharging the battery cell, detects overdischarge of the battery cell, switches the first switch circuit to an off state, and then switches the second switch circuit to an on state. The power supply device according to claim 1, wherein: 4. A battery unit which is connected in series with another battery unit and is charged or is connected in series with another battery unit and supplies electric power to a desired device. Alternatively, a battery unit includes: a first switch circuit that stops flowing out of a discharge current from the battery cell; and a second switch circuit that bypasses a current flowing into the battery cell.