JPH06111852A - Battery system - Google Patents

Abstract

(57) [Abstract] [Purpose] A battery system that can charge and discharge in a short time without waste and prevent the memory effect. [Structure] 1 is a unit 1 in which five 1.2V NiCd cells are connected in series to form a 6V battery, 2 is a unit 2 having the same structure, 3, 4, 5, 6 are SW1,
When SW1 and 2 are ON in 2, 3 and 4, SW3 and 4 are OFF, and when SW1 and 2 are OFF, SW3 and 4 are ON
So basically it works. However, during discharge, the unit 1 is switched to the unit 2 immediately before it becomes empty. At this time, all of SW 1, 2, 3, and 4 are O.
May be in N state. No. 7 of this battery system
A (minus) terminal and 8 are + (plus) terminals. 10
Is a control circuit for the switch, which generates a control signal for controlling the four switches from the voltage characteristics of charging and discharging of the units 1 and 2. 11 is a switch (SW1 to SW4)
ON / OFF selection, command circuit, control circuit 10
ON / OFF of each switch judging from the result of control by
To decide.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to rechargeable battery systems.

[0002]

2. Description of the Related Art Generally, a battery is a device that converts and uses energy associated with a chemical or physical change of a substance into electric energy, and a secondary battery according to the present invention is charged (adding battery energy). ) Refers to a battery that can be reused by regenerating the active material into the previous chemicals.

Conventionally, nickel-cadmium (nickel-cadmium) batteries have been mainly used as secondary batteries. This battery has a voltage output of 1.2V per cell, which is 5V.
They are individually assembled in series to form one unit and are configured to obtain an output voltage of 6V. Here, a cell is the minimum unit of a battery and is also called a unit cell or a unit cell. A unit is a unit of a battery in which some cells are connected in series to adjust the output voltage, and one to several units of which are connected in parallel is referred to as a battery pack.

A memory effect is one of the problems associated with charging and discharging a battery as described above. The memory effect is a phenomenon that if the battery is repeatedly recharged without being completely discharged, the discharge point in the middle of discharging is finally stored. For applications that require a high end-of-discharge voltage,
Although an apparent capacity decrease occurs with a decrease in the operating voltage (see FIG. 4), this step-down of the discharge voltage is a temporary phenomenon that is resolved by one or two complete discharges. As shown in, when the battery is recharged, the battery may be discharged and then recharged.

In FIG. 4, 16 is a discharge curve of an unused cell, and 17 is a discharge curve showing a memory effect. FIG. 5 is a flowchart for charging and discharging a conventional NiCd battery. First, the capacity of the battery unit is checked. That is, the remaining capacity C is the predetermined value C of the remaining capacity.
_It is compared whether or not _{th is} larger than _th (S21), if C ≦ 0, charging is performed (S24), and if C> 0, discharging operation is performed (S22), and then the capacity is checked again (S2).
3) If C> 0, the discharging operation is continued, and if C ≦ 0, charging is continued (S24). After charging, perform the above capacity check. That is, the full charge capacity C _max and the remaining capacity C are compared (S25), and if C _max > C, the battery is charged again (S2).
4) If C _max ≦ C, it is considered that charging has been completed, and the charging is terminated.

[0006]

However, the conventional recharging method has the following problems. In the case of a battery used in a large-capacity device such as a camcorder, it is useless to discharge it over time and recharge it when the remaining amount is large. The batteries used in portable word processors and personal computers are designed to be automatically charged when the AC power cord is connected, but if this is replaced with a method of simply discharging and then recharging, it will be discharged or When I try to take out the AC power again when it is empty, it stops working.

The present invention has been made in order to solve such a conventional problem, and does not perform a wasteful discharge operation, does not add another equipment to the load side equipment, and charges and discharges time. It is an object of the present invention to provide a battery system that can be shortened.

[0008]

In order to achieve the above object, the battery system of the present invention uses a battery unit composed of at least one or more rechargeable battery cells as a management unit for charge / discharge processing. A battery pack that is configured to be connected to a load in a time-sequential manner using a number of the battery units to utilize the discharge.
In this battery system, the battery unit with the smallest remaining capacity is recharged sequentially.

[0009]

According to the present invention, it is possible to charge and discharge only the minimum necessary battery cells by dividing the battery pack into a plurality of units for use.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2 and 3 show an example of a two unit battery system of a camcorder which is a first embodiment of the present invention. FIG. 1 is a principle diagram of a two-unit battery that best represents the features of the present invention, FIG. 2 is a time chart when switching between two units, and FIG. 3 is a flow chart when charging and discharging the unit. In FIG. 1, 9 is a two-unit battery system body, 1 is a unit 1 in which five 1.2V NiCd cells are connected in series to form a 6V battery, and 2 is a unit 2 having a similar structure. 4,
5 and 6 are SW1, 2, 3 and 4, and basically operate when SW1 and 2 are ON, SW3 and 4 are OFF, and when SW1 and 2 are OFF, SW3 and 4 are ON. However, during discharge, the unit 1 is switched to the unit 2 immediately before it becomes empty. At this time, SW1,
All 2, 3, and 4 may be in the ON state (see FIG. 2). 7 is the- (minus) terminal of this battery system,
Reference numeral 8 is a + (plus) terminal. A switch control circuit 10 generates control signals for controlling the four switches from the charge / discharge voltage characteristics of the units 1 and 2.
Reference numeral 11 is a command circuit for selecting ON / OFF of the switches (SW1 to SW4), and determines ON / OFF of each switch by judging from the result of control by the control circuit 10.

Next, in the above structure, when 7, 8 are connected to a load circuit such as a camcorder, 3, 4 (SW1, 2)
Is ON and 5, 6 (SW3, 4) is OFF, and the unit 1 starts discharging. As shown in Fig. 4, the NiCd battery does not know the remaining amount of the battery just before it is completely discharged. However, the sign of battery exhaustion comes out a few minutes before the battery can no longer operate. The unit 1 detects the voltage drop and controls it with the control circuit 10.
Is immediately before the end of discharge (t _{th in} FIG. 2), the circuit 11
First, turn ON 5,6 (SW3, 4), and after a certain time (T in FIG. 2), turn OFF 3, 4, (SW1, 2).
Switch to. By setting a fixed time T at the time of switching, it is possible to reliably switch from the unit 1 to the unit 2 without interruption. When the discharge of the unit 2 is completed, the unit 2 becomes empty, which is the conventional battery pack.

FIG. 3 is a flowchart for charging and discharging the two-unit battery, and its operation will be described below.

First, the capacity of the unit 1 is checked,
The remaining capacity C is compared with the predetermined remaining capacity _Cth (S1),
When C ≦ C _th , the battery is charged (S3), and when C> C _th ,
The unit 1 is discharged (S2), and in the subsequent capacity check (S3), if C> C _th, discharging is continued, and if C ≦ C _th , the unit 1 is charged (S4). In the capacity check after charging of the unit 1, the full charge capacity C _max and the remaining capacity C are compared (S5). If C _max > C, further charging is performed (S4), and if C _max ≦ C, the unit 1 , And check the unit 2 after charging (S6),
When C ≦ C _th , the unit 2 is charged (S9),
When C> C _th , the unit 2 is discharged (S7),
In the subsequent capacity check (S8), if C> C _th, discharging is continued, and if C ≦ C _th, unit 2 is charged (S9).
Full charge capacity C by checking the capacity after charging unit 2
_{The max} is compared with the remaining capacity C (S10), and if C _max > C, the battery is further charged (S9), and if C _max ≦ C, the charging / discharging operation ends. As described above, this battery does not seem to be different from the conventional battery pack during discharging, but when charging, only unit 1 is used and unit 2 is not used at all, as is apparent from FIG. If not, the charging / discharging of the entire battery pack is completed only by discharging and charging the unit 1, which is considered to be less than half of the time required for charging / discharging the conventional battery, and wasteful time and power are consumed. It can be omitted.

Further, the present battery can be compatible with the conventional battery, and can be used without newly adding other equipment to the load side device.

Another example is a portable word processor automatic charging system. This structure is almost the same as the battery pack of the above-mentioned embodiment, except that a battery charger is built-in, and when an AC cord is connected,
It means that the battery is charged and discharged automatically. The function and operation are the same as those in the above-described embodiment. The effect of implementing the present invention is that, in addition to the above-mentioned effect, the battery pack does not become empty during charging / discharging. In addition, there is no possibility that the battery does not operate when the AC cord is unplugged due to discharging or emptying.

[0016]

As described above, according to the present invention, the battery pack is divided into a plurality of units for use.
It has the following effects. It is not necessary to perform a wasteful discharge operation. Charge / discharge time can be shortened. Since it is compatible with conventional batteries, it can be used without adding any other equipment to the equipment on the load side. The memory effect can be prevented. Improves operability of automatic charging type AC / DC common equipment.

[Brief description of drawings]

FIG. 1 is a principle diagram of a two-unit battery system embodying the present invention.

FIG. 2 is a time chart when switching from unit 1 to unit 2.

FIG. 3 is a flowchart when charging and discharging a two-unit battery.

FIG. 4 is a discharge characteristic of a conventional NiCd battery.

FIG. 5 is a flowchart for charging and discharging a conventional NiCd battery.

[Explanation of symbols]

 1 unit 1 2 unit 2 3,4,5,6 SW1,2,3,4 7- (minus) terminal 8 + (plus) terminal 9 2 unit battery system main body 10 switch control circuit 11 switch ON / OFF Selection, instruction circuit

Claims (2)

[Claims] 1. A battery unit composed of at least one or more rechargeable battery cells is used as a management unit for charge / discharge processing, and a plurality of the battery units are connected to a load in a time-sequential order to utilize the discharge. A battery system characterized by comprising a battery pack that 2. The battery system according to claim 1,
A battery system characterized by sequentially recharging from the battery unit with the smallest remaining capacity.