JP6569624B2 - Voltage regulator - Google Patents

Description

  The present invention relates to a voltage regulator for charging or discharging a secondary battery. More specifically, the present invention relates to a voltage regulator that charges or discharges a plurality of secondary batteries in series.

  Conventionally, secondary batteries that are rechargeable batteries have been used. On the other hand, secondary batteries are often used as an assembled battery in which a plurality of secondary batteries are connected in series. Therefore, when charging a secondary battery, there is a demand for charging a plurality of batteries connected in series at a time. There exists what is described in patent document 1 as such a charging device. In the technique of this document, the voltage of each secondary battery or a plurality of battery blocks of secondary batteries connected in series during charging is detected. Then, when one voltage of each cell or battery block becomes equal to or higher than a predetermined upper limit value, switching from constant current charging to constant voltage charging is performed.

JP 2002-152984 A

  However, the conventional techniques described above have the following problems. That is, the state of charge of the secondary battery to be charged is not exactly aligned. This is because the charging method is switched based on the voltage value of the battery to be charged that has the highest battery voltage. In other words, secondary batteries other than those with the highest battery voltage may end charging without reaching the above-described predetermined upper limit value. For this reason, the state of charge of the plurality of secondary batteries that are connected in series remains uneven. Such a situation is not limited to charging a plurality of secondary batteries, but is the same when discharging.

  The present invention has been made to solve the above-described problems of the prior art. That is, the problem is that a voltage adjusting device that charges or discharges a plurality of secondary batteries in series and terminates charging or discharging so that each secondary battery is aligned with a target charging state, respectively. It is to provide.

  A voltage regulator in one aspect of the present invention is a device that regulates a voltage by charging or discharging a plurality of secondary batteries in a series connection state so as to be in a target charge state. A power supply unit capable of switching between a constant current mode in which a battery is charged or discharged at a constant current and a constant voltage mode in which a target secondary battery is charged or discharged at a constant voltage, and a plurality of secondary batteries. Connect to the power supply unit in series, and remove any secondary battery from the series connection state individually, and connect other secondary batteries to the power supply unit in series. A switch group to be in a state, a voltage detection unit that individually detects voltage values of a plurality of secondary batteries, and a current detection that detects a current value flowing through the secondary battery that is connected in series to the power supply unit Section, power supply section and switch A control unit that controls the group, and the control unit is configured to control a leading battery whose voltage value is closest to a predetermined target voltage value among secondary batteries in series connection during the constant current mode. When the voltage value reaches the target voltage value, the first switching operation for switching the power supply unit from the constant current mode to the constant voltage mode, and the current value flowing through the secondary battery in the series connection state during the constant voltage mode are determined in advance. When the target current value is reached, the first battery is removed from the series connection state by the switch group, and the remaining secondary batteries are connected in series to the power supply unit, and the power supply unit is switched from the constant voltage mode to the constant current mode. In addition to performing the second switching operation, all of the secondary batteries are connected in series by the switch group and charging or discharging is started in the constant current mode by the power supply unit. Rutotomoni, in which are configured so that all of a plurality of secondary battery is repeated a first switching operation and the second switching operation to be excluded from the series connection state.

  In the voltage regulator in the above aspect, all of the plurality of secondary batteries are connected in series by the switch group, and charging or discharging is started in the constant current mode by the power supply unit. In the constant current mode, the voltage values of the plurality of secondary batteries are individually detected by the voltage detection unit. Then, when the highest (in the case of charging) or lowest (in the case of discharging) voltage value among them becomes a predetermined target voltage value, the constant current mode is switched to the constant voltage mode (first switching operation). Then, a current value of charging or discharging is detected by the current detection unit. When the current value drops to a predetermined target current value, the switch group removes the secondary battery with the highest or lowest voltage value from the series connection state and supplies only the remaining secondary batteries to the power source. In series connection with the part. Further, the power supply unit is switched from the constant voltage mode to the constant current mode (second switching operation). Thus, the first switching operation and the second switching operation are repeated until all the secondary batteries are excluded from the series connection state. When all the secondary batteries are removed from the series connection state, charging or discharging is completed. When charging or discharging is completed, the charging / discharging state of each secondary battery is accurately aligned with the target state.

  According to this configuration, there is provided a voltage adjusting device that charges or discharges a plurality of secondary batteries in series and terminates charging or discharging so that each secondary battery is aligned with a target charging state. ing.

It is a circuit diagram which shows the state which connected the charging device which concerns on embodiment, and the secondary battery of charge object. It is a flowchart which shows the procedure of charging operation by the charging device of FIG. It is a circuit diagram which shows the state which charge was completed about one of the secondary batteries. It is a graph which shows the example of the change of the voltage value and electric current value in the process of charge by the charging device which concerns on embodiment. It is a flowchart which shows the procedure of discharge operation in the case of a discharge device.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. In this embodiment, the present invention is embodied as the charging device 1 shown in FIG. The charging device 1 includes a power supply unit 2, switches RY <b> 1 to RYn, voltage detection units V <b> 1 to Vn, a current detection unit I, and a control unit 3. In addition to these, secondary batteries E1 to En are also illustrated in FIG. However, the secondary batteries E <b> 1 to En are not part of the charging device 1.

  The power supply unit 2 is a power supply source that charges the secondary batteries E1 to En. As will be described later, the power supply unit 2 can take two operation modes of a constant current mode and a constant voltage mode. The switches RY1 to RYn are a group of switches that connect the secondary batteries E1 to En to the power supply unit 2. In FIG. 1, all the secondary batteries E <b> 1 to En are connected in series by the switches RY <b> 1 to RYn and connected to the charging device 1. However, as will be described later, by operating individual switches RY1 to RYn, any secondary batteries E1 to En are excluded from the series connection, and secondary batteries E1 to En other than the excluded batteries are excluded. Can be connected in series.

  The voltage detectors V1 to Vn are voltmeters that detect individual voltage values of the secondary batteries E1 to En. The current detection unit I is an ammeter that detects a current value of a current flowing through the secondary batteries E <b> 1 to En by the power supply unit 2. The controller 3 controls the operation of the charging device 1. Specifically, the control unit 3 operates the power supply unit 2 and the switches RY1 to RYn. As for the power supply unit 2, the operation is switching between the constant current mode and the constant voltage mode. Regarding the switches RY1 to RYn, the contents of the operation are that all the secondary batteries E1 to En are connected in series by switching individual switches or that any one of them is excluded from the series connection. The control unit 3 uses the detection voltage values of the voltage detection units V1 to Vn and the detection current value of the current detection unit I as information necessary for the operation.

  In the above configuration, the switch RY1, the voltage detection unit V1, and the secondary battery E1 are collectively referred to as CH (channel) 1. In the switch RY1, a state in which the secondary battery E1 of the channel is included in the series connection is referred to as an off state, and a state in which the secondary battery E1 is excluded from the series connection is referred to as an on state. The same applies to CH2 and below.

  The charging of the secondary batteries E <b> 1 to En by the charging device 1 configured as described above is performed as shown in the flowchart of FIG. 2 under the control of the control unit 3. First, before starting charging, all the switches RY1 to RYn are turned off. That is, all the secondary batteries E <b> 1 to En are connected in series to the power supply unit 2.

  In this state, charging of the secondary batteries E1 to En is started in the constant current mode (S1). And the individual voltage value of the secondary batteries E1-En is detected by the voltage detection parts V1-Vn (S2). Hereinafter, the symbols V1 to Vn are also used as symbols indicating the detected individual voltage values. Here, the voltage values V1 to Vn increase with the progress of constant current charging, but the target voltage value Vt is determined in advance. The target voltage value Vt is stored in the control unit 3. Therefore, it is determined whether or not each of the measured voltage values V1 to Vn has reached the target voltage value Vt (S3). As soon as charging starts, there are no voltage values V1 to Vn that have reached the target voltage value Vt. For this reason, it will be determined No in S3. In this case, S1 and S2 are further continued. That is, constant current charging is continued while detecting individual voltage values V1 to Vn.

  When the voltage values V1 to Vn increase due to the continuation of constant current charging, the one with the highest voltage will eventually reach the target voltage value Vt. At this time, the determination in S3 is Yes. Here, the control unit 3 also grasps which channel of the secondary battery has reached the target voltage value Vt. Hereinafter, this channel is referred to as CHx. Then, the operation mode of the power supply unit 2 is switched to the constant voltage mode (S4). This is the first switching operation. The voltage value in the constant voltage mode is determined so that the voltage value of CHx (which reaches the target voltage value Vt) among the secondary batteries E1 to En is maintained at the target voltage value Vt. If the voltage value of the secondary battery of a channel other than CHx exceeds the target voltage value Vt during the constant voltage mode, the channel is newly set as CHx. Thereby, further charging is continued in the constant voltage mode.

  And the electric current value of the electric current which flows into the secondary batteries E1-En from the power supply part 2 is detected by the electric current detection part I (S5). Hereinafter, the symbol I is also used as a symbol indicating the detected current value. This current value decreases with the progress of constant voltage charging, but a target current value It (“target cut current” in FIG. 2) is predetermined. The target current value It is stored in the control unit 3. Therefore, it is determined whether or not the measured current value I has decreased to the target current value It (S6). Immediately after switching to the constant voltage mode, the current value I is larger than the target current value It. For this reason, it will be determined No in S6. In this case, S4 and S5 are further continued. That is, constant voltage charging while detecting the current value I is continued.

  As the constant voltage charging continues, the current value I decreases and eventually becomes equal to or less than the target current value It. At this time, the determination in S6 is Yes. Thus, charging of the secondary batteries E1 to En corresponding to CHx is completed. Therefore, the switch corresponding to CHx among the switches RY1 to RYn is turned on (S7). That is, the secondary batteries E1 to En that are completely charged are excluded from the serial connection, and the secondary batteries E1 to En other than the excluded batteries are connected in series. This state is shown in FIG. FIG. 3 shows a state in which the switch RY2 is turned on and the secondary battery E2 is excluded from the charging target. Then, it is determined whether or not charging has been completed for all of the secondary batteries E1 to En (S8).

  When the secondary batteries E1 to En that have not yet been charged remain (S8: No), the process returns to S1. That is, the operation mode of the power supply unit 2 is switched to the constant current mode again. However, at this time, the number of secondary batteries E1 to En to be charged is reduced by one by S7. This is the second switching operation. Thereafter, the above-described processing of S1 to S8 is repeated. Accordingly, the secondary batteries E1 to En are sequentially charged one by one. When charging is completed for all of the secondary batteries E1 to En (S8: Yes), the flow of FIG. 2 ends. In this state, all of the secondary batteries E1 to En are in a state where the target voltage value Vt and the target current value It are charged.

FIG. 4 shows an example of the transition of the voltage values V1 to Vn and the current value I in the charging process according to the flowchart of FIG. In FIG. 4, the voltage value scale is shown on the left vertical axis, and the current value scale is shown on the right vertical axis. It also shows how time passes from the left to the right. FIG. 4 also shows the case of the following setting example.
Total number of secondary batteries (number of channels): 5 Target voltage value: 3.97 [V]
Constant current value: 5000 [mA]
Target current value (target cut current): 900 [mA]

  In the graph of FIG. 4, the first constant current charge (CC), the first constant voltage charge (CV), the second constant current charge, and the second constant voltage charge with the passage of time from the start of charging (left end). Charging progresses, etc.

  In the example shown in FIG. 4, only one of the five secondary batteries originally has an initial voltage that is quite close to the target voltage value Vt, and the initial voltages of the remaining four secondary batteries are clearly lower than that. Is the case. For this reason, one of the voltage values Vn reaches the target voltage value Vt immediately after the start of charging, and the first constant current charging is completed and the first constant voltage charging is switched (first switching operation). Thereafter, each voltage value Vn is maintained substantially constant, and when the current value I decreases from the constant current value to the target current value It, the first constant voltage charging is completed and the second constant current charging is switched. (Second switching operation). Thereafter, constant current charging and constant voltage charging are repeated as described above.

  Here, in the example of FIG. 4, the time required for constant current charging (CC) each time varies greatly. That is, a certain amount of time is required for the second constant current charging, but the constant current charging for the other times is short. In particular, the fifth constant current charging is so short that it is hardly recognized as a period in FIG. Also, the time required for constant voltage charging (CV) differs depending on the time, although not as long as constant current charging. The variation in the constant current charging time and the constant voltage charging time at each time depends on the variation in the initial voltages of the secondary batteries E1 to En. However, the variation in the voltage value of each secondary battery after completion of charging (Vs in FIG. 4) is only about 2 [mV]. Thus, by using the charging device 1 of this embodiment, each secondary battery E1-En can be charged uniformly.

  In the above description, the secondary batteries E1 to En are charged in both the constant current mode and the constant voltage mode. However, the present invention is not limited to this, and in the constant current mode, the secondary batteries E1 to En are charged. On the contrary, in the constant voltage mode, the secondary batteries E1 to En are slightly discharged to adjust the voltage after charging. Is also possible. This is possible by setting the target voltage value Vt slightly higher than the final target value.

  Further, the present invention can be embodied not only as a charging device for charging the secondary batteries E1 to En but also as a discharging device for discharging the secondary batteries E1 to En. In the constant current mode in that case, the voltage values V1 to Vn decrease, and the lowest voltage of them first becomes the target voltage value Vt. The channel having the lowest voltage is set to “CHx”. Of course, even in that case, the voltage values of the secondary batteries E1 to En after completion of the discharge are highly uniform. FIG. 5 shows a flowchart of the operation in the case of the discharge device. Basically, FIG. 5 is obtained by replacing “charge” in FIG. 2 with “discharge”. In FIG. 5, the secondary batteries E1 to En are discharged in both the constant current mode and the constant voltage mode, but the present invention is not limited to this. Conversely, in the constant voltage mode, it is possible to adjust the voltage after discharging by slightly charging the secondary batteries E1 to En. In the present invention, the above charging device and discharging device are collectively referred to as a voltage regulator.

  As described above in detail, according to the present embodiment, when charging the secondary batteries E1 to En, charging in the constant current mode and charging in the constant voltage mode are repeated, so that all the secondary batteries are charged. Align to the desired charge state. Thereby, the charging device which can obtain the state where the uniformity of the voltage of each secondary battery is high after the charging is completed is realized. The same applies to a discharge device that discharges a battery.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, in the voltage detectors V1 to Vn, the number of voltmeters may be less than the number of channels, and measurement of each channel may be performed by time sharing. Moreover, the kind of secondary battery used as object of charge (voltage adjustment) is not ask | required. The constant current value in the constant current mode, the constant voltage value in the constant voltage mode, the above target current value, etc. should be set appropriately according to the specifications of the target battery and the target charge / discharge state. That's fine.

1 Charging device (voltage regulator)
2 Power supply unit 3 Control unit I Current detection unit RY1 to RYn Switch (group)
V1 to Vn Voltage detector

Claims (1)

A voltage regulator for charging or discharging a plurality of secondary batteries connected in series to achieve a target charge state,
A power supply unit capable of switching between a constant current mode in which a target secondary battery is charged or discharged at a constant current and a constant voltage mode in which the target secondary battery is charged at a constant voltage or discharged at a constant voltage;
The plurality of secondary batteries are connected in series with the power supply unit, and any one of the plurality of secondary batteries is individually excluded from the series connection state, and two batteries other than those excluded are excluded. A group of switches for connecting a secondary battery in series with the power source;
A voltage detector for individually detecting voltage values of the plurality of secondary batteries;
A current detection unit for detecting a current value flowing in a secondary battery that is connected in series to the power supply unit;
A control unit for controlling the power supply unit and the switch group,
The controller is
During the constant current mode, when the voltage value of a leading battery whose voltage value is closest to a predetermined target voltage value among the secondary batteries in a series connection state becomes the target voltage value, the power supply unit is turned on. A first switching operation for switching from the constant current mode to the constant voltage mode;
During the constant voltage mode, when the current value flowing through the secondary batteries in the series connection state falls to a predetermined target current value, the switch group excludes the leading battery from the series connection state and the remaining secondary batteries. The battery is connected in series with the power supply unit, and a second switching operation for switching the power supply unit from the constant voltage mode to the constant current mode is performed.
All of the plurality of secondary batteries are connected in series by the switch group, and charging or discharging is started in the constant current mode by the power supply unit,
The voltage regulating device is configured to repeat the first switching operation and the second switching operation until all of the plurality of secondary batteries are excluded from the series connection state. .

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