JPH0424937B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a constant current generating circuit that generates a pulsating constant current of double wave or half wave rectification from an alternating current rectified voltage, which is connected to a secondary battery through a switching element. A comparison circuit compares the terminal voltage of the secondary battery with a reference voltage with the switching element in a non-conducting state for each pulsation, and when the reference voltage exceeds the terminal voltage, the switching element is made conductive. The present invention relates to a charging device.

[Problems to be solved by conventional technology and invention]

This type of charging device is well known from Utility Model Application No. 57-201040, and by monitoring the non-charging terminal of the secondary battery when the switching element is in a non-conducting state,
Since the terminal voltage of a secondary battery whose internal resistance has increased due to overdischarge can be accurately monitored, the charging time is approximately the same as that required for a normally discharged battery. However, this device does not take into consideration supplementary charging after charging is completed.

Therefore, it is an object of the present invention to further develop a charging device of the type mentioned at the beginning to also enable automatic and highly accurate supplementary charging.

[Means for solving problems]

In order to achieve this object, the present invention has a constant current generating circuit 1 which generates a pulsating constant current having a substantially constant peak value from a pulsating rectified voltage obtained by rectifying an AC power supply, as shown in FIG. , is connected in series to the secondary battery 2 to be charged via the switching element 3, and the comparison circuit 4 compares the terminal voltage _Vt of the secondary battery with a reference voltage with the switching element 3 in the non-conducting state for each pulsation. In the secondary battery charging device described at the beginning, the switching element 3 is made conductive when the reference voltage exceeds the terminal voltage _Vt .
, the first reference voltage V ₁ corresponding to the charge end voltage
and a reference voltage generation unit that generates a second reference voltage V ₂ corresponding to a lower left voltage after charging is completed;
In response to the detection signal of the temperature sensor 5a that detects the temperature of the secondary battery 2, the reference voltage is adjusted in response to temperature fluctuations in the charging end voltage and smaller temperature fluctuations in the unused voltage.
and a temperature compensator that compensates for V ₁ and V ₂ respectively, and detects that the integrated amount of charging current reaches a predetermined amount and sets the first reference voltage V ₁ instead of the second reference voltage V ₂ . A current detection circuit 6 is attached to supply the current to the comparison circuit 4.

[Effect]

During normal charging, since the current detection circuit 6 does not detect current, the reference voltage is applied to the comparison circuit 4.
V ₂ (see Figure 2) is input, and one terminal voltage
Since V _t has fallen below this due to neglect, the reference voltage V ₂ exceeds the terminal voltage V _t every pulsation, turning on the switching element 3. As a result, pulsating constant current charging is performed in the constant current generating circuit 1, and when the current detecting circuit 6 integrates the input current amount and reaches a predetermined amount, the reference voltage V ₁ is sent to the comparing circuit 4.
be supplied. As charging progresses, the terminal voltage V _t
reaches the end-of-charge voltage and exceeds the first reference voltage _V1 , so the switching element 3 can no longer conduct, and charging ends. As a result, the current detection circuit 6 returns to its normal state and the reference voltage is replaced by _V2 .

When the terminal voltage V _t decreases due to self-discharge and falls below the reference voltage V ₂ , the comparator circuit 4 activates the switching element 3 again to perform supplementary charging. If a large amount of current is consumed by the load, the current detection circuit 6 detects the accumulated current amount and outputs the terminal voltage.
Perform normal charging until V _t reaches the charge end voltage. During this time, the reference voltages V ₁ and V ₂ are compensated by their respective temperature compensators, so that charging can be performed without excess or deficiency with respect to fluctuations in ambient temperature.

[Embodiment of the Invention] FIG. 3 shows an example of a circuit configuration when a 6-cell lead-acid battery is used as the secondary battery 12.

In the figure, 11 is a constant current generation circuit,
AC power supply voltage double-wave rectifier circuit 11a and secondary battery 1
Resistor R with a sufficiently large resistance value for the internal resistance of 2
1. The SCR1 functions as both a switching element and a comparison circuit, and is attached with a reverse voltage blocking diode D1 that protects its gate circuit.

15 is the first voltage corresponding to the end-of-charge voltage of 14.5V.
A reference voltage V ₁ of
This is a reference voltage generation circuit that generates _V2 . This circuit consists of a programmable Zener diode D2
, resistors R2 to R7 connected to their control terminals, and a transistor Tr1 that functions as a temperature sensor attached to the secondary battery 12.

16 is a current detection circuit, and resistors R11, R1
2. Temperature compensation diode D3 and transistor
Constant current drive circuit composed of Tr2 and resistor R
13, R14 and a capacitor C11, and a switching transistor Tr that is turned on when the integrated current level reaches a predetermined value.
It consists of 3.

The programmable Zener diode D2 receives a rectified voltage as an input, and generates a constant voltage of 2.5 V with no temperature fluctuation at its control terminal when the rectified voltage exceeds a predetermined level, and has a constant voltage of 2.5 V at its anode according to the reciprocal of the voltage division ratio. The reference voltages V ₁ and V ₂ are generated in an arterial manner.

That is, when the switching transistor Tr3 is off, the following _V2 is generated, assuming that the combined resistance of the resistors R2, R4, R5, and R6 is _R1 .

V ₂ = 2.5V × (R ₁ + R3) / R3 Furthermore, the combined resistance is R ₁ and transistor Tr1
Since the resistor _RCE is added in parallel between the collector and emitter of Tr1, the voltage drop across resistor R6 is reduced so that the collector current of Tr1 becomes 1/N of the current flowing through R2 due to the negative temperature characteristic of the resistance value. , Tr.
By setting the base-to-emitter voltage V _BE of 1, V ₂ changes in accordance with the curve B in which the unused voltage has little temperature variation shown in FIG.

On the other hand, when the switching transistor Tr3 is on, it produces the following _V1 .

That is, the voltage division ratios K _{1 and} K ₂ are K ₁ = R2 + R3 / R3, K ₂ = (R5 + R6) R _CE / R7, and the combined resistance R ₂₁ , R ₂₂ R ₂₁ = R2R3 R ₂₂ = R4 + R7 (R5 + R6 R _CE ). Then, the following V ₁ is generated.

V ₁ = 2.5V x (K ₁ R ₂₂ / R ₂₁ + R ₂₂ + K ₂ R ₂₁ / R ₂₁ + R ₂₂ In this equation, Tr1 enters K ₂ with a positive coefficient,
1, as the temperature rises, V _BE decreases, so more collector current flows, and R _CE seen from the outside decreases.
As K ₂ decreases, V ₁ is temperature compensated for larger temperature fluctuations in the end-of-charge voltage, which corresponds to the temperature fluctuation curve of the unused voltage shown in FIG.

The operation is as follows.

In the normal charging process, each time a rectified voltage is generated, the second reference voltage V ₂ exceeds the terminal voltage V _t , and SCR 1 acts as a comparison circuit, causing a switching current signal to flow between its gate and anode, causing ignition. Then, a double-wave rectified constant current is supplied to the secondary battery 12. During this time, the current detection circuit 16 detects, for example, a current equivalent to 20 pulsating constant currents per second, and switches the reference voltage to _V1 . When charging is completed and the terminal voltage V _t exceeds the reference voltage V ₁ , SCR1 becomes non-conductive and charging ends.

As a result, the transistor of the power supply detection circuit 16
Tr3 is turned off again and the reference voltage is switched to _V2 .

When the terminal voltage V _t falls below the reference voltage V ₂ due to self-discharge, supplementary charging with a small number of pulsations is performed to ensure complete charging. During this time, if the load is consuming a large amount of current and a charge equivalent to 20 or more pulsations per second is connected, the voltage switches to the reference voltage V ₁ and complete charging is performed until the charge end voltage is reached. .

In the above embodiment, the reference voltage generation section and the temperature compensation section share a circuit for both reference voltages, but both reference voltage generation sections are configured independently and each reference voltage output is detected by current. The switching may be performed using the circuit 16. The current detection circuit can also be configured with a counter that counts the number of pulsations of the input constant current.

〔Effect of the invention〕

As described above, according to the present invention, not only does it not require a long time to charge an over-discharged secondary battery, but also the secondary battery can be fully charged at all times even when a load is connected or the battery is left unused. Can be kept in a charged state.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the circuit configuration of a charging device according to the present invention, FIG. 2 is a diagram explaining its operation, FIG. 3 is a diagram showing the circuit configuration of a charging device according to an embodiment of the present invention, and FIG. FIG. 3 is a diagram showing temperature fluctuation characteristics of charging end voltage and left-standing voltage. 2,12... Secondary battery.

Claims (1)

[Scope of Claims] 1. A secondary battery is connected via a switching element to a constant current generation circuit that generates a pulsating constant current with a nearly constant peak value from a rectified voltage of an AC power supply,
This switching element is controlled by a comparison circuit that compares the terminal voltage of the secondary battery with a reference voltage in a non-conducting state for each pulsation, and outputs a switching signal when the reference voltage exceeds the terminal voltage. In a secondary battery charging device, the reference voltage generation circuit is configured to include a reference voltage generation circuit that generates a first reference voltage corresponding to the end-of-charging voltage and a second reference voltage corresponding to a lower left voltage after the end of charging. and a temperature compensation unit that compensates for temperature fluctuations in the charging end voltage and smaller temperature fluctuations in the discharge voltage according to a detection signal from a temperature sensor that detects the temperature of the secondary battery, and A charging device comprising a current detection circuit that detects when the amount of current reaches a predetermined amount and supplies the first reference voltage to the comparison circuit instead of the second reference voltage. 2 The switching element and comparison circuit are one
The charging device according to claim 1, characterized in that it is constituted by an SCR.