JPH088749B2 - How to charge the battery pack - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method of charging a battery set, such as a nickel cadmium battery, for charging a battery set. The charging current value is changed according to the number of cells. This is to prevent an excessive temperature rise of the power transformer.

[Background of the Invention]

A charging device capable of charging a battery group having a different number of cells (battery group having different voltages) includes a charging current detection means, a current control element such as an SCR inserted between a power transformer and a battery group, and the current. The charging current is controlled so that the average value of the charging current is always constant regardless of the battery voltage.

That is, since the instantaneous charging current increases as the battery voltage decreases, that is, the number of cells decreases, the average charging current is controlled by controlling the current controlling element so that the ON state period of the current controlling element is correspondingly shortened. I try to keep it constant.

Therefore, there is a problem that the effective value of the charging current increases as the battery set having a lower battery voltage is charged, and the heat generation of the power transformer increases.

[Object of the Invention]

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art,
It is to suppress an excessive temperature rise of the power transformer.

[Outline of Invention]

The present invention focuses on the fact that the voltage of the battery group decreases to around 0 V when it is over-discharged, but it recovers immediately after starting charging, charging at a predetermined charging current for a predetermined time from the start of charging, and When the battery voltage is detected after a lapse of time, the detected battery voltage and the reference voltage are compared to determine the number of cells, and when it is determined that the battery voltage is smaller than the reference voltage, that is, the number of cells is small. By charging with a small charging current, an excessive temperature rise of the power transformer is suppressed.

Example of Invention

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 1 is an AC power supply, 2 is a power transformer, 3, 4, 7 and 8 are diodes, and 5 and 6 are SCs constituting the current control element of the present invention.
R and 9 are resistors 9a, 9b and 9c, an operational amplifier 9d, and a capacitor 9e.
Is a constant voltage power source including a voltage regulator 10a, a diode 10b, and a smoothing capacitor 10c, and serves as a power source for the control means 11 and the like described later. For example, the control means 11 including a single-chip microcomputer includes a computing means (CPU) 11a, ROM 11b, RAM 11c, timer 11d, external interrupt input port 11e, input port 11
f, an output port 11g, and an A / D converter 11h. Reference numeral 12 is a battery voltage output detecting means composed of resistors 12a and 12b,
The battery voltage of the battery group 14 is divided and the divided voltage is input to the A / D converter 11h. 13 is a transistor 13a, resistor 1
SCR ignition means consisting of 3b and 13c and diode 13d. Reference numeral 14 denotes a battery group to be charged, and the battery group 14 having a different number of cells (battery voltage is different) is connected. Fifteen
Is a charging device comprising the power transformer 2, rectifying diodes 3, 4, 7 and 8, SCRs 5, 6, charging current detection means 9, constant voltage power supply 10, control means 11, battery voltage detection means 12, and SCR ignition means 13. Is.

Next, the operation will be described with reference to the flowchart of FIG. When the power is turned on, the control means 11 performs the following control.

The charging current command value Icmd and the threshold value of the battery voltage for switching the charging current, that is, the reference voltage value Vs of the present invention are set (steps 101 to 102), and the battery group 14 is in the connection standby state. When the battery group 14 is connected to the charging device 15, the 10-minute timer data is set, the timer 11d is started, and the constant current charging control is performed based on the charging current command value Icmd set in step 101 (step 103-106).

At the time when the 10-minute timer counts up, that is, when 10 minutes elapse, the output signal of the battery voltage detection means 12 is changed.
A / D conversion is performed by the A / D converter 11h, and the battery voltage value Vref is taken in (step 108). Whether the battery voltage value Vref is larger or smaller than the reference battery voltage value Vs, that is, whether the number of cells of the battery group 14 is large or small. Is determined (step 109).

When the battery is over-discharged, its voltage drops to around 0V, but it has the characteristic that the voltage recovers immediately after starting charging.In order to accurately identify the battery voltage,
The battery voltage is determined after the lapse of minutes. Battery voltage value Vr
When ef is smaller than the reference battery voltage value Vs, it is determined that the number of cells in the battery group 14 is small, and the charging current command value Icmd is rewritten (step 110) to perform charging with a small charging current. On the contrary, when the battery voltage value Vref is larger than the reference battery voltage value Vs,
It is determined that the number of cells in the battery group 14 is large and the charging current command value Ic
md continues charging as it is, and thereafter, constant current control is performed so as to reach the set charging current value, and charging is continued (step 111).

As a result, when the number of cells of the battery group 14 is small, charging is performed with a charging current smaller than the charging current command value Icmd, so that the temperature of the power transformer will not rise excessively.

〔The invention's effect〕

As described above, according to the present invention, the battery voltage detected after the lapse of a predetermined time from the start of charging is compared with the reference voltage to determine the number of cells in the battery group, and it is small when the number of cells is small. Since the charging is performed with the charging current, it is possible to suppress the excessive temperature rise of the power transformer.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, and FIG.
The figure is a flow chart for explaining the operation of the present invention. In the figure, 2 is a power transformer, 3, 4, 7, and 8 are diodes, 5 and 6 are SCRs, 9 is a charging current detection means, 10 is a constant voltage power supply, 11 is control means, 12 is battery voltage detection means, 13 is
SCR ignition means, 14 is a battery assembly, and 15 is a charging device.

Claims (1)

[Claims] 1. A current detecting device for detecting a charging current, a voltage detecting device for detecting a voltage of a battery set to be charged, a current control element inserted between a power transformer and a battery set for controlling the charging current. And a control means for sending a signal for switching the value of the charging current corresponding to the battery voltage detected by the voltage detection means to the current control element, wherein the battery set is charged with a predetermined charging current for a predetermined time. The battery voltage detected by the voltage detecting means after a predetermined time determines the number of cells in the battery group, and the battery voltage is smaller than the reference voltage value, that is, the charging current is smaller than the predetermined charging current when the number of cells in the battery group is small. To continue charging, and to continue charging without changing the predetermined charging current when the detected battery voltage is larger than the reference voltage value in a battery group, that is, in a battery group having a large number of cells. A method of charging a battery set characterized by the above.