JPS6412169B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a built-in rechargeable battery as an emergency power source in emergency lights, guidance lights, and various electronic devices, and uses a rechargeable battery with a minute current of 1/20C to 1/30C during normal times. This relates to an emergency power supply charging circuit that charges the battery and operates the device using the built-in battery in the event of a power outage.

The conventional emergency power supply charging circuit is
By connecting a rectifier circuit to the next output side and connecting a current compensation resistor to the output side of the rectifier circuit to increase the power supply impedance, the charging current to the rechargeable battery is stabilized. The effects of voltage fluctuations could not be prevented. For example, when the voltage of the input power source is high, the charging current to the rechargeable battery becomes large, causing an overcharging phenomenon. Additionally, if the voltage of the input power source is low, the charging current to the rechargeable battery will be small, and as a result, sufficient charging current for stable charging (compensatory charging) will not be obtained.
Due to insufficient charging, the energy of the battery could not be used effectively. In addition, in order to stabilize the charging current, increasing the current compensation resistor will increase heat loss, and increasing the capacity of the built-in battery to compensate for insufficient charging due to a drop in input power supply voltage will eliminate unnecessary In addition to increasing costs,
This was a step backwards from the era of energy conservation, as it required powering up emergency power sources.

The present invention has been made in view of the above conventional problems, and is a power-saving charging circuit that can always perform stable and safe charging without being affected by voltage fluctuations of the input power supply (commercial 100V power supply). The purpose is to provide

Hereinafter, the present invention will be explained based on drawings showing embodiments thereof. In Fig. 1, the part surrounded by a dashed line is a phase control circuit, and this phase control circuit consists of a series circuit consisting of a resistor _R1 and a capacitor C.
A programmable unidirectional transistor 1 (hereinafter referred to as PUT) that turns on when the charging voltage of the capacitor C reaches a predetermined voltage;
A silicon controlled rectifying element 2 (hereinafter referred to as SCR) whose gate is controlled by 1 and various resistors R ₂ , R ₃ ,
It is composed of R ₄ . Reference numeral 3 denotes a rechargeable battery built into the device, which is connected to the anode side of the SCR 2 and forms a charging circuit using phase control. The part surrounded by the dashed line is a voltage detection circuit that detects the input voltage and controls the charging current to the capacitor C of the phase control circuit. VR is connected to divide the input voltage, and its middle terminal is connected to the base of transistor Tr ₁ , and the emitter and collector of transistor Tr ₁ are connected to resistor R ₅ ,
Connected across capacitor C via _R6 . Incidentally, a pulsating DC voltage obtained by rectifying the secondary output side of a transformer for lowering the AC commercial power source is applied to the input terminals 4 and 4'.

The operation in the above circuit configuration will be explained. The phase control circuit operates when the charging voltage of capacitor C, through which charging current flows through resistor _R1 , reaches a predetermined voltage.
Turn on PUT1 and turn on SCR2. As a result, the rechargeable battery 3 is charged.
In this case, if there is no voltage detection circuit according to an embodiment of the present invention, the phase control has a constant conduction angle regardless of the level of the input voltage Vin, so it is directly affected by fluctuations in the input voltage Vin. It is. However, when the voltage detection circuit in one embodiment of the present invention is provided, the input voltage Vin
If is high, the charging current to capacitor C can be reduced to lengthen the charge-up time of capacitor C, and the operating point of SCR2 can be delayed to narrow the conduction angle. That is, when the input voltage Vin is high, the transistor Tr ₁ of the voltage detection circuit is turned on and the charging current to the capacitor C is shunted through the resistor R ₆ , transistor Tr ₁ and resistor R ₅ . Capacitor C
Since the charging current to PUT decreases, the charge-up time of capacitor C increases, resulting in
As the operating time of SCR 1 is delayed, the operating point of SCR 2 is also delayed. In addition, when the input voltage Vin is low, the transistor Tr ₁ of the voltage detection circuit is turned off and all the charging current flowing through the resistor R ₁ flows to the capacitor C. As a result, the charge-up time of the capacitor C is shortened. For,
The operating point of SCR2 becomes faster and the conduction angle is widened.

Note that the operation of the transistor Tr ₁ is on,
Rather than switching off, the switch operates in an unsaturated region, and is configured so that a shunt current proportional to the level of the input voltage Vin flows. Also variable resistance VR
acts as a potentiometer to determine the operating point.

Figure 2 a, b, and c show the above operating conditions, where a shows the V B waveform when the input voltage Vin is low, b shows the V _B waveform when the input voltage Vin is normal, and c shows the V _B waveform when the input voltage Vin is normal. shows the V _B waveform when the input voltage Vin is high. When the input voltage Vin is low, the conduction angle (conduction width) t ₁ of the SCR 2 is longer than the conduction angle (conduction width) t ₂ of the SCR 2, but the charging voltage ΔV _B1 to the rechargeable battery 3 is lower than b ΔV is lower than _B2 . Furthermore, when the input voltage Vin is high, the conduction angle (conduction width) t ₃ of the SCR 2 becomes shorter than the conduction angle (conduction width) t ₂ of the SCR 2, but the charging voltage ΔV _B3 to the rechargeable battery 3 becomes b It is higher than ΔV _B2 of , and the average value of the peak value is averaged for all a, b, and c, and as a result,
A constant current can be passed through the rechargeable battery 3 regardless of fluctuations in the input voltage Vin.

In the above embodiment, the rechargeable battery 3 is connected to the SCR 2 of the phase control circuit, but if a load such as a resistor is connected instead of the rechargeable battery 3, it can be used as a constant current power source. be able to.

As described above, according to the present invention, the following various excellent effects can be achieved.

(1) Conventionally, a current compensation resistor was connected to the output side of the charging power supply in order to stabilize the charging current, but the power loss consumed by this current compensation resistor was large, and it also generated heat. However, in the present invention, the charging current to the capacitor of the phase control circuit is shunted to change the conduction angle of the silicon-controlled rectifying element, so there is no unnecessary power loss and heat generation occurs. A stable current can be passed without any problems, and as a result, a safe charging circuit that is not affected by voltage fluctuations of the input power source can be obtained.

(2) There is no need for heat sinks, etc., as there is no unnecessary power loss and no heat generation occurs.
As a result, the size of the emergency power source can be reduced.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
Figures a, b, and c are waveform diagrams showing the operating states of the circuit in Figure 1. ... Phase control circuit, R ₁ ... Resistor, C ... Capacitor, 2 ... Silicon controlled rectifier, Tr ₁ ...
...transistor, VR...variable resistor.

Claims (1)

[Claims] 1. A silicon-controlled rectifier element that has a series circuit consisting of a resistor and a capacitor connected to a DC input terminal, and whose gate is controlled by a programmable union transistor that turns on when the charging voltage of the capacitor reaches a predetermined value. and a load connected in series to this element, and connected to both ends of the capacitor to shunt the charging current to the capacitor according to fluctuations in the input voltage applied between the DC input terminals. 1. A charging circuit characterized in that a current dividing means is provided, which is comprised of a variable resistor that connects the base of this transistor to the midpoint of the resistance division.