JPS631818B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a battery charging device for sequentially and individually charging individual battery blocks.

Conventional methods for charging a plurality of battery blocks include a series charging method in which a plurality of battery blocks are connected in series, and a parallel charging method in which a plurality of batteries are connected in parallel. In the series charging method, the same charging current flows through all battery blocks even if the amount of remaining electricity varies depending on the individual battery blocks, so there is a drawback that some battery blocks may become overcharged or undercharged. . Furthermore, in the parallel charging method, in the case of rapid charging, a charging control device must be provided for each charging branch of the battery block, which has the disadvantage that the overall device becomes larger.

The present invention was basically invented in view of these points, but it is also intended to increase the amount of charge of each battery block as much as possible. I will explain based on this. FIG. 1 is a schematic diagram of a charging device according to the invention. In this drawing, reference numeral 1 serves as a charging power supply circuit, and includes a step-down circuit 2 that steps down an AC input e, and a rectifier circuit 3 that rectifies its step-down output. A plurality of charging branches 5 ₁ to 5 _o are connected in parallel to the charging power supply circuit 1 for individually charging each battery block 4 (for example, one NiCd battery). Each charging branch is provided with connection terminals 6, 6 of the battery block 4 and an electronic switch 7, and each electronic switch is sequentially controlled to open and close by the output of an automatic switching circuit 8.

Reference numeral 9 denotes a control circuit for detecting the state of charge of the battery block 4 during charging and controlling the charging of the battery block 4, which is constructed as follows. That is, the voltage dividing circuit 10 is connected in parallel to the battery block 4 that is being charged.
, a detection circuit 12 and a storage circuit 13 connected to the voltage dividing circuit via a switch circuit 11, and a comparison circuit 14 that detects a predetermined difference voltage between the output of the detection circuit 12 and the storage voltage of the storage circuit 13. Become. The switch circuit 11 is intermittently closed by, for example, one timing pulse per cycle of the AC input e, and when the switch circuit 11 is closed, the detection circuit 12 detects the proportional voltage of the battery block 4 and also The storage circuit 13 stores a voltage that is a predetermined voltage V lower than the maximum voltage of the proportional voltages.

The charging voltage characteristic of the battery block has a peak point a indicated by A in FIG. 2, and then decreases.
In this decreasing region, the charge amount characteristic B becomes fully charged.

The detected proportional voltage of the detection circuit 12 has a characteristic C, and the storage voltage of the memory circuit 13 has a characteristic D. Therefore, the storage voltage of the storage circuit 13 is at the peak point.
The voltage becomes Vc at t ₁ . Further, as is clear from the characteristic C, the output of the detection circuit 12 decreases after the peak time t ₁ , and at the time t ₂ when the predetermined difference voltage between the decreasing detection circuit output and the storage voltage Vc becomes zero voltage, the comparison circuit 14 produces an output. Characteristic E is characteristic C, D
This is the differential voltage characteristic of

Next, details of the control circuit 9 will be explained based on FIG. The voltage dividing circuit 10 is made up of a series circuit of resistors _R1 to _R4 , and has voltage dividing terminals _P1 to _P3 . The switch circuit 11 consists of three switch circuits _S1 to _S3 . The detection circuit 12 includes a first potential storage element _M1 , and is connected to a voltage dividing terminal _P2 via a second switch circuit _S2 . The memory circuit 13 is a second and third potential memory element.
M ₂ , M ₃ and a first operational amplifier A ₁ , the second potential storage element M ₂ is connected to the voltage dividing terminal P ₃ via the third and fourth switch circuits S ₃ and S ₄ , and the third The potential storage element _M3 is connected to the voltage dividing terminal _P1 via the first switch circuit S1 _.
connected to. The first operational amplifier _A1 inputs the outputs of the second and third potential storage elements _M2 and _M3 , and outputs when the output of the second potential storage element _M2 matches the output of the third potential storage element _M3 . occurs, and the fourth switch circuit _S4 is opened. Therefore, the storage voltage of the second potential storage element M ₂ remains unchanged until reaching the peak time t ₁ of the third potential storage element M 2 .
Follow the voltage of M ₃ . The comparison circuit 14
It consists of a second operational amplifier A ₂ which receives the outputs of the potential storage elements M ₁ and M ₂ as input.

Thus, until the peak time t ₁ , each potential storage element M ₁
~The memory voltage of _M3 increases, but at the peak point
After t ₁ , the storage voltage Vc of the second potential storage element M ₂ is the fourth
While it is constant due to the opening of switch circuit _S4 ,
The storage voltage of the first and third potential storage elements M ₁ and M ₃ decreases in accordance with the charging voltage characteristic A. For this reason, the comparator circuit 14 outputs an output at time t 2 when a predetermined difference voltage (zero voltage in the specific example) between the decreasing storage voltage of the first potential storage element M ₁ and the storage voltage Vc of the _second potential storage element M ₂ is reached. occurs, and the automatic switching circuit 8 selects the first
The electronic switch 7 of the second charging branch 5 ₁ is opened, and then the electronic switch 7 of the second charging branch 5 ₂ is closed. When the charging branches 5 ₁ and 5 ₂ are switched, the storage voltage of each potential storage element M ₁ to M ₂ is discharged by instantaneous closing of the reset switches RS ₁ to RS ₃ by the output of the automatic switching circuit 8. It is returned to the initial state and used for detecting the charge of the battery block 4 of the next stage charging branch ₅₂ .

In this way, the battery blocks 4 individually attached to each of the charging branches 5 ₁ to 5 _o are sequentially charged. For example, if the battery block 4 is not attached to the third charging branch ₅₃ , the electronic switch 7 of the _third charging branch 53 is automatically turned off after charging of the battery block 4 of the second charging branch ₅₂ is completed. The circuit is closed based on the output of the switching circuit 8, but since there is no battery block, the voltage applied to the voltage dividing circuit 10 is large, and the comparator circuit 14 detects an abnormal voltage and outputs an output. The electronic switch 7 of the third charging branch ₅₃ is opened, and the electronic switch 7 of the fourth charging branch ₅₄ is closed. In this way, if no battery block 4 is attached to a charging branch, that charging branch is skipped and all battery blocks 4 are individually charged.

As described above, according to the present invention, since each battery block is charged individually and sequentially, all battery blocks with different amounts of remaining electricity can be properly charged, and the detection mechanism for the state of charge of the battery blocks is Only one is required, and the charging device can be made smaller. Further, the predetermined state of charge of the battery block is detected after the peak of the charging voltage characteristic of the battery block, so that the amount of charge of the battery can be brought close to the amount of full charge. Furthermore, the state of charge of the battery block is detected by a detection circuit as a voltage dividing point voltage of a voltage dividing circuit that divides the battery voltage, and a memory circuit that stores the maximum voltage of the battery voltage is stored at a higher potential than the voltage dividing point. When the storage voltage of the storage element connected to the high potential point of the voltage dividing circuit via a switch becomes equal to the voltage of the low potential point of the voltage dividing circuit which is lower in potential than the voltage dividing point, the switch is opened and the In order to increase the storage voltage in a stepwise manner, the storage element is supplied with power from a high potential point voltage that is higher than the voltage division point voltage that is the detection voltage of the detection circuit, and the memory element is supplied with power from a high potential point voltage that is higher than the voltage division point voltage that is the detection voltage of the detection circuit. Voltage tracking response can be improved. Furthermore, since the memory voltage is always set to the initial state at the start of charging due to the function of the reset circuit, erroneous detection at full charge can be prevented.

[Brief explanation of the drawing]

The drawings show specific examples of the present invention; FIG. 1 is a schematic diagram of a charging device, FIG. 2 is a charging characteristic diagram of a battery block, and FIG. 3 is a detailed circuit diagram of a control circuit. 4, 4... Battery block, 5 ₁ to 5 _o ... Charging branch, 12... Detection circuit, 13... Memory circuit, 14
... Comparison circuit, 8 ... Automatic switching circuit, RS ₂ ... Reset means.

Claims (1)

[Claims] 1 has a plurality of charging branches for charging individual battery blocks, a voltage divider circuit for dividing the battery voltage of the battery block being charged, and a detection circuit for detecting the voltage division point voltage of the voltage divider circuit; When the storage voltage of a storage element connected via a switch to the high potential point of the voltage dividing circuit, which has a higher potential than the voltage dividing point, becomes equal to the low potential point voltage of the voltage dividing circuit, which has a lower potential than the voltage dividing point. , the switch is opened to increase the storage voltage stepwise, and a predetermined difference voltage between the output of the detection circuit and the storage voltage of the storage circuit, which decreases after the maximum voltage of the battery voltage. A battery comprising: a comparison circuit for detecting the voltage; and an automatic switching circuit for sequentially controlling opening/closing of the charging branch circuit based on the output of the comparison circuit; charging device.