JPH0669268B2 - Charging circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a charging circuit commonly used for 100V / 200V power source regions.

(Background Art) FIGS. 5 and 6 are already disclosed by the present applicant in Japanese Patent Laid-Open No. 58-103837.
FIG. 7 shows an example of the configuration of the charging circuit proposed in the publication, and FIG. 7 shows the configuration of the control circuit 3 in FIGS. 5 and 6.

To explain the configuration in FIG. 5, a rectifier DB such as a diode bridge and a primary winding of a transformer T ₂ for a control circuit power supply are connected in parallel to each other at terminals 1a and 1b to which an AC power supply is connected, rectifier primary winding L ₁ of the transformer T ₁ of the power converter to the DC output terminals of the _DB, the transistor Q, parallel capacitor C _S1 for the series circuit and a smoothing by the resistance R _E of the current detection from each other as a switching element It is connected to the. In addition, the primary winding L of the transformer T ₁
A series circuit for spike absorption by a resistor R _C and a capacitor C _C is connected in parallel with _1, and a series circuit of a rectifying diode D ₁ and a secondary battery B is connected to both ends of a secondary winding L _2. There is.

On the other hand, the base of the transistor Q is connected to the positive electrode of the rectifier DB through the starting resistor R _B1 and the control circuit 3
Connected to the control output terminal OUT of the transistor Q, and between the base and the emitter of the transistor Q, a series circuit of a tertiary winding L ₃ magnetically coupled to the transformer T ₁ , a resistor R _B2 , and a speed-up capacitor C _B1 . And the emitter of the transistor Q is connected to the detection input terminal IN of the control circuit 3 via the resistor R _IN ′. In addition, the detection input terminal IN and the rectifier
A resistor R _C ′ is connected between the positive electrode of DB and the positive electrode.

On the other hand, one end of the secondary winding of the transformer T ₂ has a diode D ₂
Is connected to the power supply input terminal V _CC of the control circuit 3 via a capacitor C _S2 , and the power supply input terminal V _CC is connected to the negative electrode of the rectifier DB together with the other end of the secondary winding of the transformer T ₂ .

Further, in FIG. 6, only the connection point of the other end of the resistor R _C ′ is different, and the other end of the resistor R _C ′ is connected to the connection point of the tertiary winding L ₃ of the transformer T ₁ and the resistor R _B2. Has been done.

As shown in FIG. 7, the control circuit 3 in FIGS. 5 and 6 includes a power supply section 31, an oscillation section 32, a comparison section 33, a holding circuit 34,
The output section 35 is composed of Q _{1 to} Q _{8, which} are transistors, Z are zener diodes, CP ₁ and CP ₂ are comparators, R _{1 to} R ₁₆ are resistors, and C ₁ is a resistor.
Indicate capacitors respectively.

Therefore, in the charging circuit shown in FIGS. 5 and 6, when an AC power source such as a commercial power source is applied to the terminals 1a and 1b, the rectified and smoothed DC voltage is passed through the rectifier DB and the capacitor C _S1 to the transformer T. ₁ primary winding L ₁ and transistor Q
Transistor Q is added to the series circuit of
Base current is supplied by _B1 to start conduction, and tertiary winding L
Due to the positive feedback action of ₃ , the transistor Q turns on rapidly. When the transistor Q is turned on, its collector current (primary current of the transformer T ₁ ) continues to increase linearly, but its current value is detected by the resistor R _E inserted in series with the transistor Q and reaches a constant value. Then the control circuit 3
By this, the base of the transistor Q is clamped to the ground level and turned off, and the maximum value of the primary current is kept constant. On the other hand, on the secondary side of the transformer T ₁ , the energy stored in the primary winding L ₁ when the transistor Q is on is released from the secondary winding L ₂ through the diode D ₁ when the transistor Q is off, A constant charging current is supplied to the secondary battery B. In addition, the control circuit 3 releases the base of the transistor Q again after the clamp is continued for a certain period to control the oscillation period to be constant. By these operations, the average value of the charging current to the secondary battery B can be kept constant even if the value of the AC power source applied to the terminals 1a and 1b fluctuates over a wide range.

In addition, the resistors R _IN ′ and R _C ′ shown in FIGS.
Is for correcting the voltage detected by the resistor R _E according to the magnitude of the voltage of the input AC power supply, and is applied to the detection input terminal IN of the control circuit 3 as the voltage of the AC power supply increases. The voltage is increased and the peak value of the current flowing through the primary winding L ₁ of the transformer T ₁ is reduced. That is, when the capacitor C _S1, which is connected in parallel between the output terminals of the rectifier DB in FIG. 5 and FIG. 6 a small volume for the purpose of miniaturization, the primary winding L ₁ of the transformer T _1, the series of the transistor Q becomes the voltage applied to the circuit is a pulsating, the proportion of the period the voltage is less pulsating waveform changes in accordance with the maximum value, the primary winding L ₁ of the transformer T ₁
This is because, when the crest value of the current flowing through is controlled to be constant, the average charging current becomes excessive as the voltage of the AC power supply increases.

Then, FIG. 8 shows the relationship between the DC input voltage and the output current related to the charging. As shown by the solid line a → b → c, the charging is performed in accordance with the increase of the DC input voltage from the point b. The current decreases linearly. And
Due to such characteristics, if an AC voltage is input, the average output current becomes constant regardless of the voltage. In addition, from point a to point b
Is the low voltage characteristic of the circuit, that is, the control circuit 3
Is determined by the characteristics of self-excited oscillation that is not controlled by. Further, FIG. 9 shows the relationship between the waveform of the voltage that is full-wave rectified by the rectifier DB and is input, and the output current (charging current) supplied to the secondary battery B.
_The charging current decreases as the amount exceeds _b .

By the way, the characteristic between points a and b in FIG. 8 is determined by the low voltage characteristic of the device as described above, and the power source V _cc for the control circuit 3 to operate normally in this section is also The voltage supplied to the resistor R _E by the collector current flowing when the transistor Q is turned on is added to the voltage determined by the ratio of the resistors R _c ′ and R _IN ′ and input to the detection input terminal IN of the control circuit 3. Therefore, the collector current flowing in the transistor Q is controlled, but the collector current flowing in the transistor Q is small between points a and b because the input voltage is low.
The divided voltage value by the resistors R _c ′ and R _IN ′ is also small, and the control circuit 3
Since it does not reach the reference voltage of, the peak value of the collector current is not controlled and the current amplification factor h _{fe of the} transistor Q is
Therefore, the collector current is decided.

By the way, in order to increase the output in this kind of circuit, the current amplification factor h _fe of the switching transistor Q is increased to meet the demand for quick charging of the storage battery. It suffices to increase the value of the collector current by means of the above means. Then, although the low voltage characteristic is improved as shown by the one-dot chain line a → b ′ → c in FIG. As described above, the DC input voltage V _IN shifts to the lower side, and the output in the AC100V system lowers than before.

On the other hand, in order to secure the output in the AC100V system, if the resistance value of the resistor R _IN ′ is reduced and the ratio of the resistor R _C ′ and the resistor R _IN ′ is increased, the point b becomes like the point b ″. It is possible to secure the output in the AC100V system by shifting to the higher DC input voltage V _IN , but the ratio of the resistance R _C ′ and the resistance R _IN ′ becomes large, so the slope of the point b ″ → c ″. Becomes smaller, AC200V
The output of the system greatly increases, and it becomes impossible to control the output to a predetermined value.

(Object of the Invention) The present invention has been proposed in view of the above points, and an object of the present invention is to control the average value of the charging current to be constant at a high output and even in a 100V / 200V power source region. It is to provide a charger that can.

DISCLOSURE OF THE INVENTION The present invention will be described in detail below with reference to the drawings illustrating embodiments.

FIG. 1 shows a first embodiment of the present invention, in which a constant voltage element Z _{D such} as a Zener diode is inserted in series with a resistor R _C ′ of an input voltage detection block A composed of a voltage dividing circuit. It has features. The other circuit configurations are the same as those in FIGS. 5 and 7 described above.

Therefore, FIG. 2 shows the relationship between the DC input voltage and the output current related to charging, and FIG. 3 shows the waveform of the voltage input after being full-wave rectified by the rectifier DB and the output current supplied to the secondary battery B. It shows the relationship with (charging current), but if the break voltage of the constant voltage element Z _D is selected so that it conducts when a 100 V system voltage is applied as at point b ₁ , the input voltage In a section where is low, no voltage is generated in the resistors R _C ′ and R _IN ′,
Since the input bias is not applied to the detection input terminal IN of the control circuit 3, the output does not decrease. Then, in the section where the input voltage is higher than the point b ₁ , the ratio of R _C ′ / R _IN ′ is b ₁ →
If you set it so that it has an appropriate slope like c ₁ ,
From the time when the input voltage exceeds the point b ₁ , the resistance R _C ′, R _IN ′
A voltage is generated in the voltage, a bias is applied to the voltage detected by the resistor R _E , the output current is reduced, and the output can be controlled to be constant on the low voltage side and the high voltage side.

FIG. 4 shows a second embodiment corresponding to FIG. 6 of the conventional example, in which a constant voltage element Z _D is inserted between the tertiary winding L ₃ and the resistor R _C ′. . The operation is similar to that of the first embodiment shown in FIG.

(Effect of the Invention) As described above, in the present invention, the series circuit of the primary winding of the transformer and the switching element is connected to the DC power source obtained by rectifying the AC power source to turn on the switching element. A charging circuit for charging a secondary battery by rectifying the electric power obtained in the secondary winding of the transformer by being driven off, the feedback circuit being connected to the control terminal of the switching element in positive feedback and A third winding that is magnetically coupled,
An output terminal is connected to the switching element, a detection input terminal is connected to a resistor that detects a current flowing through the switching element, and the control end of the switching element is grounded when the detected voltage reaches a predetermined value. And a control circuit for clamping to a level, wherein the detection input terminal divides the DC power supply, and the divided voltage is added to the detection voltage of the current detection resistor to be applied to the control circuit. Is connected, the on / off repetition cycle of the switching element is kept constant, and the on time is appropriately controlled according to the voltage of the AC power source to control the charging current to the secondary battery to be constant. In the charging circuit, a constant voltage element is provided in the voltage dividing circuit so that the divided voltage of the DC power supply is added to the detection voltage only when the DC power supply is higher than a predetermined value. Since, (b) there is no reduction in the output current at the low voltage side of the AC power source (AC100V system), and is not the output current is too increases on the high pressure side (AC200V system), obtained a stable output current 100 V / 200V
A charging circuit that is shared by the local community can be configured.

(B) Since the ripple voltage may be large, the smoothing capacitor becomes small, and the size and cost can be reduced.

And so on.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of a charging circuit of the present invention, FIGS. 2 and 3 are operation explanatory diagrams thereof, and FIG. 4 is a circuit configuration diagram showing a second embodiment of the present invention. 5 to 7 are configuration diagrams showing a conventional charging circuit, and FIGS. 8 and 9 are operation explanatory diagrams thereof. A ...... input voltage detection block, _{Z D} ...... constant voltage element, 3
...... Control circuit, B ... Secondary battery, Q ... Transistor,
R _E , R _IN ′, R _C ′ ... Resistance

Claims (1)

[Claims] 1. A secondary circuit of the transformer by connecting a series circuit of a primary winding of the transformer and a switching element to a DC power source obtained by rectifying an AC power source and driving the switching element on / off. A charging circuit for rectifying the electric power obtained in the winding to charge a secondary battery, the tertiary winding being positively feedback-connected to the control end of the switching element and magnetically coupled to the transformer, An output terminal is connected to the switching element and a detection input terminal is connected to a resistor that detects a current flowing through the switching element,
And a control circuit that clamps the control end of the switching element to the ground level when the detected voltage reaches a predetermined value, and divides the DC power supply into the detection input terminal, and the divided voltage is A voltage divider circuit that is added to the detection voltage of a resistor for current detection and is added to the control circuit is connected, and the ON / OFF repetition cycle of the switching element is kept constant, and the ON time depends on the voltage of the AC power supply. In a charging circuit in which the charging current to the secondary battery is controlled to be constant by providing a constant voltage element in the voltage dividing circuit, and the DC voltage is applied only when the DC power source is higher than a predetermined value. A charging circuit characterized in that a divided voltage of a power supply is added to a detection voltage.