JPH0373218B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a charging circuit for rapidly charging a battery to be charged such as Ni-Cd.

(Background Art) Conventionally, in this type of quick charger using a reverse-blocking three-terminal thyristor (SCR), a reverse-blocking three-terminal thyristor (SCR) is connected to a reverse-blocking three-terminal thyristor (SCR) at a predetermined phase for each waveform of a pulsating power supply voltage obtained by rectifying an AC power supply. Phase control is performed by applying a trigger signal to the terminal thyristor, and at the end of charging, the conduction period is shortened to lower the average value of the charging current.

However, in the conventional case, a trigger signal is given to the reverse-blocking three-terminal thyristor for each waveform of the pulsating power supply voltage, so even if the average value of the charging current can be lowered at the end of charging, gas generation inside the battery may occur. On the other hand, since the charging current is passed without ensuring sufficient time to absorb the current, there is a fear that the battery may deteriorate.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and its purpose is to provide sufficient gas absorption time for gas generation in the battery to be charged at the end of charging. To provide a charging circuit which reduces battery deterioration and further reduces switching loss by increasing the switching speed of a transistor in a trigger signal generating circuit.

(Disclosure of the Invention) In order to achieve the above-mentioned object, the present invention connects a pulsating current power supply to the base of a first transistor connected via a reference voltage source to a pulsating current power supply whose emitter is connected to a reference power supply voltage. A voltage obtained by dividing the voltage by a first resistor, a second resistor, and a parallel circuit of a capacitor is applied, and when the base voltage exceeds the voltage of the reference voltage source, the first transistor is turned on. a voltage comparator circuit having a base connected to the collector of the first transistor, an emitter resistor connected to the emitter and a pulsating current power supply via the emitter resistor; A trigger signal generation circuit that applies the voltage at the connection point with the emitter of the transistor to the gate of a reverse blocking three-terminal thyristor, and a battery to be charged is connected to the cathode, and is connected to a pulsating current power supply via the battery to be charged. The reverse blocking type three-terminal thyristor described above is used.

EXAMPLES The present invention will be explained below by way of examples. FIG. 1 shows a block diagram of the present invention, which includes a step-down circuit 1 that steps down the AC power supply voltage, a rectifier circuit 2 that rectifies the AC that has been stepped down in the step-down circuit 1, and a circuit that detects that a charging current is flowing. a current detection circuit 3;
A display circuit 4 that emits light based on the detection by the current detection circuit 3, and a battery pack that generates a constant current.
A reference current generation circuit 6 that flows into the battery temperature detection circuit 5 provided in the BP compares the input voltage obtained by dividing the pulsating current power supply voltage with the reference voltage generated in the battery temperature detection circuit 5 to determine the reference voltage. A voltage comparator circuit 8 that operates the trigger signal generation circuit 7 when the input voltage exceeds it, a reverse blocking three-terminal thyristor 9 (hereinafter referred to as thyristor 9) that conducts with the trigger signal of the trigger signal generation circuit 7, and the thyristor. A sensor open detection circuit 11 controls the thyristor 9 by detecting an incomplete connection between the battery temperature detection circuit 5 and the battery 10 to be charged, such as Ni-Cd, which is charged by a charging current flowing through the battery temperature detection circuit 5. When the charging voltage V _B of the battery 10 to be charged is at a predetermined level, conduction of the thyristor 9 is restricted to perform charging control. FIG. 2 shows a circuit that embodies the block of FIG. 1, and the operation of the embodiment circuit will be explained in detail using this concrete circuit. The step-down circuit 1 is composed of a step-down transformer 14, and has power supply connection terminals a,
The AC voltage of the AC power supply connected to AC power source B is stepped down and full-wave rectified by the diodes 12 and 13 of the rectifier circuit 2, and the pulsating current is used as the power supply voltage of the charger A. Charger A
The battery pack BP is detachably attached to the battery pack BP, and the battery 10 to be charged and the battery temperature detection circuit 5 of the battery 10 to be charged are connected to the terminals c,
d and e for electrical connection during installation. A thyristor 9, a battery to be charged 10 in the battery pack BP, and a current detection circuit 3 are connected between the output terminals of the rectifier circuit 2.
A series circuit of current detection resistors 15 is connected.
The current detection circuit 3 includes a current detection resistor 15, a transistor 18 connected between the output terminals of the rectifier circuit 2 via a display circuit 4 consisting of a light emitting diode 16, and a resistor 17, and a transistor 18 connected to the current detection resistor 15. It consists of a base resistor 19 connected in parallel via a base emitter, and a thyristor 9.
Then, when a charging current flows through the battery to be charged 10 and the current detection resistor 15, the transistor 18 is turned on and the light emitting diode 1 is connected via the transistor 18.
6 to indicate that it is being charged.
A voltage comparator circuit 8 connects the pulsating power supply voltage to resistors 20 and 21.
The divided voltage divided by is applied to the base, and the collector is connected to the positive output terminal of the rectifier circuit 2 via the resistor 25, and the emitter is connected to the variable resistor 2.
2, a variable resistor 24 of the battery temperature detection circuit 5,
A first transistor 26 connected to the negative output terminal of the rectifier circuit 2 via a diode 23, each of the above-mentioned resistors 20, 21, 25, and a variable resistor 22.
and a capacitor 33 connected in parallel to the resistor 21. A constant current diode 3 is connected to the series circuit between the variable resistor 24 and the battery temperature detection circuit 5.
A constant current flows from the reference current generating circuit 6 consisting of 4, and a voltage that becomes the reference voltage of the voltage comparator circuit 8 is generated in the series circuit, and this reference voltage is compared with the base voltage of the transistor 26. , if the base voltage is higher than the emitter voltage of the transistor 26 plus the drop voltage V _BE26 , the transistor 26 is turned on, and if it is lower, the transistor 2 is turned on.
6 is now turned off. The trigger signal generation circuit 7 includes a second transistor 27 whose base is connected to the collector of the transistor 26 and a resistor 28.
Connect the series circuit between the output terminals of the rectifier circuit 2,
The emitter of the transistor 27 is connected to the gate of the thyristor 9 through a diode 29, so that when the transistor 27 is turned on, the thyristor 9 is fired through the diode 29. The sensor open detection circuit 11 is a variable resistor 2
The battery temperature detection circuit 5 is composed of a transistor 32 that applies to its base a voltage obtained by dividing the voltage of a series circuit of the battery temperature detection circuit 5 and the battery temperature detection circuit 5 by resistors 30 and 31.
When the transistor 32 is disconnected, the base potential of the transistor 32 rises and the transistor 32 is turned on, which causes the base of the transistor 27 of the trigger signal generation circuit 7 to be grounded via the transistor 32. The transistor 27 of the generation circuit 7 is forcibly turned off when the battery temperature detection circuit 5 is disconnected to stop charging. Further, at this time, the charging current flowing through the SCR 9 disappears, the current detection circuit 3 does not operate, and the light emitting diode 16 of the display circuit 4 is turned off, indicating that the battery temperature detection circuit 5 is not connected.

Next, the operation of the charging circuit of the present invention will be explained. Assuming that during charging when the battery pack BP is attached and connected to the charger A, the pulsating power supply voltage shown in Fig. 3a is generated from the rectifier circuit 2, when the pulsating power supply voltage rises, First, the base voltage of the voltage comparator circuit 8 responds to the rise in the charging voltage of the capacitor 33, so that it increases during the rising period until the current flowing through the constant current diode 34 reaches a certain level as shown in FIG. 3c. In the transistor 26, the base voltage never exceeds the emitter voltage, so the base current of the transistor 26 does not flow, and the collector current does not flow through the transistor 26, so that the potential of the collector does not decrease. Therefore, as soon as the pulsating voltage applied to the base of the transistor 27 of the trigger signal generation circuit 7 exceeds the voltage drop between the base and emitter of the transistor 27, the switching speed is changed due to the decrease in the collector potential of the transistor 26. Faster than when affected. Now, when the transistor 27 is turned on, the voltage at the connection point ○a between the emitter resistor 28 and the emitter of the transistor 27 increases as the pulsating power supply voltage increases, as shown in FIG. 5b. In this voltage increase, when the voltage at this connection point ○A exceeds the sum voltage of the forward drop voltage V _F29 of the diode 29, the drop voltage V _G between the gate cathode of the thyristor 9, and the battery voltage V _B , the gate of the thyristor 9 A current flows and turns on, causing a charging current to flow to the battery 10 to be charged, and charging begins. On the other hand, in the voltage comparison circuit 8, the voltage across the capacitor 33 reaches the reference voltage, that is, the flat level of the waveform shown in FIG.
When the voltage drop between _the base and emitter of
shall be. Therefore, in the initial state where the voltage of the battery 10 to be charged is low, the thyristor 9 starts conducting quickly;
Conversely, as the battery voltage V _B increases, the time point at which the thyristor 9 starts conducting becomes later. And the peak value of the voltage at the connection point ○A is the battery voltage V _B and the diode 29
When the sum of the forward voltage drop V _F29 and the voltage drop V _G between the gate and cathode of the thyristor 9 is no longer exceeded, the thyristor 9 is not conductive and the charging is stopped.
That is, depending on the timing at which the transistor 26 of the voltage comparison circuit 8 turns on, a battery voltage V _B that can turn off the thyristor 9 can be set, and this battery voltage V _B becomes the charging control voltage.
In the initial charging operation, since the battery voltage _VB is low, the emitter voltage of the transistor 27, that is, the voltage at the connection point ○A, is at the point X, which is lower than the peak value Y shown in FIG. A gate current flows to turn on the thyristor 9. Therefore, for each waveform of the pulsating current power supply, the thyristor 9 turns on, so that the current detection resistor 15 of the current detection circuit 3
A charging current flows almost continuously to light up the light emitting diode 16 of the display circuit 4, and due to the afterimage of the human eye, the light emitted from the light emitting diode 16 appears to be in a continuous light emitting state, and the user is aware of this light emission. You can tell when the battery is charging.

By the way, after the above-mentioned charging stop occurs at the end of charging, the thyristor 9 is turned on only when the voltage drops due to self-discharge of the battery 10 to be charged, and supplementary charging is performed. Here, the switching operation of turning off the transistor 26 of the voltage comparator circuit 8 is performed when the voltage is lower than the value of the pulsating power supply voltage when it is turned on, due to the discharge time constant of the charge of the capacitor 33. , the emitter voltage of the transistor 27 of the trigger signal generation circuit 7, that is, the voltage at the connection point ○a, is the voltage of the transistor 27.
There is a ΔV between the voltage when 6 is on and the voltage when it is off.
Only the bottom occurs. Therefore, at the end of charging, the battery voltage V _B decreases due to self-discharge, and the battery voltage V _B and the diode 29
When the sum of the forward voltage drop V _F29 and the voltage drop V _G between the gate and cathode of the thyristor 9 falls below, the thyristor 9 is turned on and supplementary charging is performed for the period of the corresponding pulsating current waveform. . Here, the peak value Y at the connection point ○a in the first half of the pulsating flow waveform shown in Figure 3b
In a place where there is no difference between the peak value Z at the connection point ○A in the second half and the battery voltage V _B decreases and falls below the peak value Z in the second half, if the thyristor 9 is turned on, charging will occur in a short period of time. Therefore, in the first half of the next pulsating current waveform, although the battery voltage V _B does not fall below the peak value Y of the first half, there is a high possibility that the thyristor 9 will be turned on again when it falls below the peak value Z of the second half. As a result, there is a risk that the battery will not be able to take the time to absorb the gas generated inside the battery.

On the other hand, by providing a difference ΔV between the peak value Y in the first half and the peak value Z in the second half of connection point ○A, when the battery voltage V _B falls below the peak value Y in the first half, the thyristor When 9 is turned on, the battery is charged during the period of that waveform, so in the next pulsating current waveform, the battery voltage V _B will be the peak value Y, Z in the first half or the second half.
The possibility that the voltage will drop below the threshold decreases, and the period until the next turn-on operation of the thyristor 9 occurs becomes relatively long. Result Battery to be charged 10
This provides sufficient time to absorb internal gas generation, thereby preventing battery deterioration and overcharging. FIG. 4a shows the charging current waveform at the beginning of charging, FIG. 4b also shows the charging current waveform at the end of charging, and FIG. 4c shows an enlarged waveform of the peak value of the battery voltage V _B at the end of charging.

However, at the end of charging, a charging current flows intermittently with respect to the pulsating current waveform, and the light emitting diode 16 of the display circuit 4 flashes, allowing the user to know that charging is complete. .

By the way, when performing such quick charging,
Since the battery voltage to be controlled varies as V ₁ , V ₂ , V ₃ , etc. as shown in Figure 5 depending on the temperature, it is necessary to set the temperature characteristics of the control operation in accordance with the battery temperature characteristics. The charging circuit is set using the following method. In other words, the switching timing of the transistor 27 of the trigger signal generation circuit 7 for triggering the thyristor 9 on the charger A side is determined by the on/off of the transistor 26 of the voltage comparison circuit 34, and the on/off of the thyristor 9 is determined by the on/off of the transistor 26 of the voltage comparison circuit 34. ○The voltage at point A, the battery voltage V _B , the voltage drop between the gate and cathode of thyristor 9 V _G , and the diode 2
This is determined by the relationship between the forward drop voltage V _F29 and the sum voltage of the transistors 26 and 27. Assuming that there is no temperature change in the battery pack BP and there is a temperature change in the charger A, each transistor 26, 27 The voltage drops V _BE26 and V _BE27 between the base and emitter of the transistors, the forward voltage drop V _F29 of the diode 29, and the voltage drop V _G between the gate and cathode of the thyristor 9 each change according to a predetermined temperature coefficient, 26, 27
This affects the switching operation of the thyristor 9 and the switching operation of the thyristor 9. Therefore, the conditions of each element are set so that the temperature characteristics of these elements are corrected so that the temperature characteristics of the control operation of charger A become zero with respect to the temperature change on the charger A side. In this case, set the element constants so as to satisfy the following conditions.

R ₂₀ +R ₂₄ /R ₂₀ ∂V _BE26 /∂T≒∂V _BE26 /∂T＋∂V _F29
/∂T+∂V _G /∂T By the way, the battery voltage V _B at the end of charging changes depending on the battery temperature, and the charging control voltage needs to be changed accordingly, as explained in Figure 5. However, in the present invention, the battery temperature detection circuit 5 is provided in the battery pack BP, and the reference voltage of the voltage comparison circuit 8 is determined by using the temperature characteristics of the diode 23 and the variable resistor 24 of the battery temperature detection circuit 5. change the
The voltage across the resistor 28 (○ point voltage )
(the maximum reference voltage to be compared with the sum voltage of the battery voltage V _B , the drop voltage V _G between the gate and cathode of the thyristor 9, and the forward drop voltage V _F29 of the diode 29). This allows charging control to be performed in accordance with the temperature characteristics of the battery 10 to be charged, and the temperature characteristics of the battery temperature detection circuit 5 are expressed as R ₂₀ +R ₂₁ /R ₂₁ ∂V _F29 /∂T. Set it to suit your gender.

For differences in the number of batteries, settings can be made in the same way as described above by changing the division ratio of resistors 20 and 21 and the quantities of diodes 29 and 23, and fine adjustment can be made by changing the current value of constant current diode 34. The temperature characteristics may be matched. still
V _BE26 is the voltage drop between the base and emitter of the transistor 26, and R ₂₀ and R ₂₁ are the resistors 20 and 21.
Further, V _F23 indicates the forward voltage drop of the diode 23.

By the way, since charging is completed as described above, charging completion control can be carried out more smoothly if the waveform of the peak value Y at connection point ◯◯ has sharp edges.

Now, if we look at the operation of the transistor 26, we will see that
The voltage increases with a pulsating waveform, and until the voltage rises to the voltage corresponding to the peak value Y, transistor 2
6 is off, and when the voltage rises to the peak value Y, the base current begins to flow through the transistor 26. However, if the capacitor 33 were not present, the current flowing through the resistor 20 and into the resistor 21 would flow through the transistor 26. Since the flow also starts to flow to 26, the resistance 20,2
The base current to the transistor 26 is insufficient until the voltage at the connection point 1 stops increasing, the power supply voltage further increases, and the voltage at the connection point increases, and the waveform of the peak value Y does not sharpen. When the capacitor 33 is present, the base current can be supplemented, and the waveform of the peak value Y becomes sharp.

Until the collector voltage of the transistor 26 decreases, the transistor 27 conducts current and generates the voltage at the connection point ○A. However, when the collector voltage of the transistor 26 decreases, the base voltage of the transistor 27 becomes lower than the emitter voltage, and the transistor 27 27
Excess electrons in the base region of can be quickly removed, and as a result, the waveform of the peak value Y at the connection point ○A becomes sharp (=switching speed becomes faster). The value of the current flowing through the transistor 27 increases as the power supply voltage increases, and of course, unless the waveform of the peak value Y is sharp, the loss will increase. Changes in V _BE due to self-heating of the transistor 27 affect the control characteristics of charging completion, so
It is necessary to suppress self-heating as much as possible,
Reducing loss can suppress this self-heating.

(Effects of the Invention) The present invention connects a reference voltage source to the emitter and connects the pulsating current power supply voltage to the base of the first transistor connected to the pulsating current power supply via the reference voltage source, and connects the pulsating current power supply voltage to the first resistor and the second resistor. a voltage comparator circuit that applies a voltage obtained by dividing the voltage by a parallel circuit of a resistor and a capacitor, and turns on a first transistor when the base voltage exceeds the voltage of the reference voltage source; The second transistor has a base connected to the collector of the transistor, an emitter resistor connected to the emitter, and a pulsating current power supply via the emitter resistor. A trigger signal generation circuit that applies a voltage to the gate of the reverse blocking type 3-terminal thyristor, and the reverse blocking type 3-terminal thyristor connected to the pulsating current power source with the battery to be charged connected to the cathode via the battery to be charged. Therefore, when the pulsating power supply voltage rises, the base voltage of the first transistor can be lowered during the charging period of the capacitor, and as a result, the collector current does not need to flow through the first transistor. The second transistor can be turned on immediately when the pulsating power supply voltage exceeds the voltage drop between its base and emitter, increasing the switching speed compared to the case without a capacitor, and reducing the switching loss. In addition, the capacitor's charge can delay the off operation of the first transistor, and as a result, the pulsating power supply voltage at the timing at which the first transistor turns on changes from the pulsating current at the timing at which the first transistor turns off. Therefore, the voltage peak value in the second half of the pulsating current waveform generated in the emitter resistance when the second transistor of the trigger signal generation circuit is turned on can be lower than the voltage peak value in the first half. Therefore, the thyristor trigger at the end of charging is performed at the voltage peak value in the first half, and charging at the end of charging can be performed for each pulsating current waveform unit.As a result, the supplementary current increases and the charging period is made intermittently. This makes it possible to obtain a sufficient period for absorption of gas generated within the battery at the end of charging, and has the effect of preventing battery deterioration, overcharging, etc.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of an embodiment of the present invention.
Figure 2 is a specific circuit diagram of the same as above, Figures 3 a to c and Figures 4 a to c are time charts for explaining the operation of the same,
FIG. 5 is a characteristic diagram showing the relationship between the battery temperature and the charging control voltage, in which 7 is a trigger signal generation circuit, 8 is a voltage comparison circuit, 9 is a thyristor, 10 is a battery to be charged, and 20 is a 1 is a resistor, 21 is a second resistor, 26 is a first transistor, 27 is a second transistor, and 33 is a capacitor.

Claims (1)

[Claims] 1 A reference voltage source is connected to the emitter, and a pulsating current power supply voltage is connected to the base of the first transistor, which is connected to the pulsating current power supply via the reference voltage source, and the pulsating current power supply voltage is connected to the first resistor and the second transistor.
a voltage comparator circuit that applies a voltage obtained by dividing the voltage by a parallel circuit of a resistor and a capacitor, and turns on a first transistor when the base voltage exceeds the voltage of the reference voltage source; The second transistor has a base connected to the collector of the transistor, an emitter resistor connected to the emitter, and a pulsating current power supply via the emitter resistor. A trigger signal generation circuit that applies a voltage to the gate of the reverse blocking type 3-terminal thyristor, and the reverse blocking type 3-terminal thyristor connected to the pulsating current power source with the battery to be charged connected to the cathode via the battery to be charged. A charging circuit characterized by: