JPH03218231A - Charger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a charging device.

BACKGROUND ART Conventionally, a charging device has had a circuit configuration as shown in FIG.

In this circuit configuration, a drive signal from the control circuit 4 is applied to the base of the charge output switch transistor 7, and conduction is established between the collector and emitter of the charge output switch transistor 7 to charge the output voltage of the secondary winding of the conversion transformer 3. It is supplied to output terminals 1.0 and 1.1. The resistor 8 is for preventing erroneous conduction due to leakage current of the charge output switch transistor 7 itself when there is no drive signal from the control circuit 4 to the base of the charge output switch transistor 7.

The diode 9 is for preventing the battery voltage from being discharged through the resistor 8 into the control circuit 4 from the battery connected to the charging output terminal 10.11. 1
is a DC power supply that is connected to the primary winding of the conversion transformer 3 via the main switching element 2 and allows current to flow therethrough.

Problems to be Solved by the Invention In such a conventional circuit configuration, the following problem occurs due to the use of the discharge prevention diode 9, which is effective only in preventing discharge from the battery.

(1) Diode 9 for preventing discharge when charging the battery
The charging output terminal voltage decreases by the forward voltage VF of , and the battery charging time increases.

(2) The internal loss of the charging device is caused by the discharge prevention diode 9
The product of the forward voltage Vp and the charging output current Io increases by VFXIo, causing an increase in the temperature inside the charging device and reducing the reliability of each component inside the charging device.

The present invention solves the above-mentioned conventional problems with a simple configuration, and aims to provide a charging device with short charging time and high reliability.

Means for Solving the Problems In order to solve the above problems, the present invention connects a series circuit of a diode and a capacitor in parallel with the diode of the secondary side rectification and smoothing circuit, or connects the input stage of the diode of the rectification and smoothing circuit to one side. A series circuit of a diode and a capacitor is connected between the charging output terminals, and a resistor is connected or directly connected between the connection point of the three diodes and the capacitor and the base of the charging output switch transistor.

Effect of the present invention With the above configuration, a reverse bias voltage can be easily applied between the emitter and the base of the charge output switch transistor without the need for a separate winding, and the reverse bias voltage can be easily applied between the emitter and the base of the charge output switch transistor from the control circuit. When there is no drive signal, it is possible to prevent erroneous conduction due to leakage current of the charge output switch transistor itself.

Therefore, the conventional resistor for preventing erroneous conduction is not required, and therefore the diode for preventing discharge of the battery voltage is not required.

Embodiment FIG. 1 is a circuit diagram of an embodiment of the charging device of the present invention.

In Figure 1, 1 is a DC power supply, 2 is a main switching element, 3 is a conversion transformer, 4 is a control circuit, 5 is a secondary side rectifier diode, 6 is a secondary side rectifier smoothing capacitor, 7 is a PNP type charging A transistor for an output switch, 10 and 11 a charging output terminal, 12 a rectifier diode for a reverse bias power supply, 13 a smoothing capacitor for a reverse bias power supply, and 14 a resistor.

A voltage equal to the difference between the forward voltage of the secondary side rectifier diode 5 and the forward voltage of the rectifier diode 12 for reverse bias power supply is applied to the smoothing capacitor 13 for reverse bias power supply, and the voltage including the high frequency ringing component is smoothed, so that the reverse bias is At the connection point between the power supply rectifier diode 12 and the reverse bias power supply smoothing capacitor 13, a positive voltage is generated with respect to the cathode of the secondary rectifier diode 5.

Furthermore, since the cathode of the secondary rectifier diode 5 is connected to the emitter of the charge output switch transistor 7, the voltage drop generated by the connection resistance between the cathode and the voltage generated in the reverse bias power supply smoothing capacitor 12 is also reduced by the resistance. A reverse bias voltage is applied between the emitter and pace of the charge output switch transistor 7 via the charge output switch 14.

When there is no drive signal from the control circuit 4 to the base of the charge output switch transistor 7, the reverse bias voltage cancels the collector leakage current of the charge output switch transistor 7, thereby preventing erroneous conduction of the charge output switch transistor 7. can do.

Therefore, for the same purpose, the resistor 8 connected between the emitter and base of the charge output switch transistor 7 in the conventional circuit shown in FIG. Voltage is no longer discharged to the control circuit 4, and the 8th control circuit of the conventional circuit
The power diode 9 shown in the figure for preventing discharge becomes unnecessary.

When a drive signal is applied from the control circuit 4 to the base of the charging switch transistor 7, the voltage at the connection point between the rectifier diode 12 for reverse bias power supply and the smoothing capacitor 13 for reverse bias power supply is applied to the control circuit 4 via the resistor 14. No reverse bias voltage is applied between the emitter and base of the inflow charging switch transistor 7, but the transistor 7 is forward biased by a drive signal and conducts between the collector and emitter.

In addition, by connecting a series circuit of a rectifier diode 12 for reverse bias power supply and a smoothing capacitor 13 for reverse bias power supply in parallel with the secondary side rectifier diode 5, it is safe from short circuits and open failures of the reverse bias power supply rectifier components. perform an action.

As described above, with the simple circuit, the power diode for preventing discharge can be omitted, thereby shortening the battery charging time and improving the reliability of the internal parts of the charging device.

2 to 4 show other embodiments of the present invention.

That is, the embodiment shown in FIG. 2 differs from FIG. 1 in that the reverse bias power supply capacitor 13 is connected between one end of the reverse bias power supply rectifier diode 12 and the output terminal 11. , Fig. 3 shows a configuration in which two secondary side rectifier diodes 5 are used and a choke coil 15 is connected to the secondary winding, and Fig. 4 shows a configuration in which both the configurations in Figs. 2 and 3 are added. The operation is basically the same as in Fig. 1.

Effects of the Invention As described above, according to the present invention, the following effects are produced with an extremely simple circuit.

(1) By omitting the discharge prevention power diode, the charging output terminal voltage increases and the battery charging time, which is one of the basic performances of a charging device, is shortened.

According to the experiment, charging output voltage 1.2.5V, charging current 1
．． According to the present invention, in the charging device of No. 68, FIG.
As shown in FIG. 6, the output voltage increases by 0.4 μ and the charging time is shortened by 25 minutes.

(2) By reducing the internal loss of the charging device, the internal temperature rise is reduced and the reliability of internal components is improved. According to the experiment, the charging output voltage is 12.5■, and the charging current is 1.6A.
In the charging device according to the present invention, the internal loss can be reduced to 0.
As shown in Figure 7, the internal air temperature decreased by 3W.
deg decreases.

8. Deterioration of parts due to temperature is generally said to follow the Arrhenius model equation below.

1 n L=A+E. /K・
T■7 Lifespan, E8 Activation energy A, K
Constant, T For absolute temperature electrolytic capacitors, the 10°02 times law holds true from the above Arrhenius model, and a temperature drop of 3 degrees is 2
3.'O=1.23, or 23% longer life.

(3) Since the power diode for preventing discharge can be omitted, it is useful for downsizing and cost reduction of the charging device.

[Brief explanation of drawings]

FIG. 1 is a temperature rise characteristic diagram of the air inside the retractor showing an embodiment of the charging device of the present invention, and FIG. 8 is a circuit diagram showing a conventional example. 1...DC power supply, 2...Main switching element, 9 3...Conversion transformer, 4...Control circuit, 5...2 Next side rectifier diode, 6...
・Secondary side smoothing capacitor, 7...Charging output switch transistor, 10.11...Charging output terminal, 12...Reverse bias power supply rectifier diode, 13... ...Reverse bias power supply capacitor, 1
4...Resistor, 15...Choke coil.

Claims (1)

[Claims] A DC power source is connected to the primary winding of the conversion transformer via the main switching element, and a charging output terminal is connected to the secondary winding of this conversion transformer via the secondary side rectifying and smoothing circuit and the charging output switch transistor. , connect a series circuit of a diode and a capacitor in parallel with the diode of the secondary rectifier and smoothing circuit, or connect a series circuit of a diode and a capacitor between the input stage of the diode of the secondary rectifier and smoothing circuit and one charging output terminal. and connect a resistor between the connection point of this diode and capacitor and the base of the charging output switch transistor, or connect it directly, and create a control circuit that controls the main switching element by the output voltage of the secondary winding. A charging device provided.