JPH0638396A - Charger - Google Patents

Abstract

(57) [Abstract] [Purpose] In a charger for charging a rechargeable secondary battery such as a nickel-cadmium storage battery, continuous overcharging or charging is performed even if the voltage of the secondary battery is 0V. An object of the present invention is to provide a charger that can normally charge a secondary battery without causing an inconvenient operation such as the absence. [Structure] A first diode is connected to obtain a flyback output from a first secondary winding of a high frequency switching transformer, and a second diode is obtained from a second secondary winding of the high frequency switching transformer to obtain a forward output. By properly connecting, the first secondary winding and the second secondary winding do not interfere with each other, and the output voltage of the first secondary winding decreases because the voltage of the secondary battery is 0V. Even the second 2
It is possible to obtain a charger that can normally charge a secondary battery having a voltage of 0 V without lowering the output voltage of the secondary winding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charger using a switching power supply circuit.

[0002]

2. Description of the Related Art In recent years, as a charger for charging a rechargeable secondary battery such as a nickel-cadmium storage battery, a charger using a switching power source in its power source section has been widely used in order to reduce the size and weight.

Hereinafter, a conventional type of charger which can charge two batteries will be described.

FIG. 2 is a circuit block diagram of a conventional charger. In FIG. 2, 1 and 2 are AC input terminals, 3
Is a rectifying / smoothing circuit for rectifying / smoothing an AC input. Four
Is a high-frequency switching transformer, which has a first primary winding P1, a second primary winding P2, a first secondary winding S1, and a second secondary winding S2. Reference numeral 5 is a high frequency switching element, and 6 is a switching control circuit section. 7 is the first secondary winding S1 of the high frequency switching transformer 4
Is a rectifying diode that rectifies a high-frequency AC voltage output to a DC voltage to obtain a DC voltage, but has a polarity opposite to that of the first primary winding P1 in order to obtain a flyback output of the first secondary winding S1. Is connected to the terminal a of the first secondary winding S1. A smoothing capacitor 8 smoothes the DC voltage. 9 is a rectifying diode of the second secondary winding S2,
Similar to the rectifier diode of No. 8, it is connected to the terminal c of the second secondary winding S2 to obtain the flyback output. 1
0 is the smoothing capacitor. Reference numeral 11 is a charging current control circuit section, 12 is a charging control circuit section, 13 is an output diode for preventing a reverse current from the battery, and 14 is 2
It is an output switching relay that switches the output to one battery. Reference numeral 15 is a constant voltage circuit unit which outputs a constant voltage which is a power supply voltage and a reference voltage of the charge completion detection circuit unit 12 and the output switching relay 14. Reference numeral 16 is a photocoupler for feeding back the output fluctuation on the secondary side to the switching control circuit unit 6 on the primary side. Reference numeral 17 is a first secondary battery charged by a charging current output from the charger,
Is a second secondary battery.

With respect to the charger configured as described above,
The operation will be described below. First, an AC power supply is input to the AC input terminals 1 and 2 and converted into a DC voltage by the rectifying / smoothing circuit 3. When this DC voltage is applied, oscillation is started by the high frequency switching transformer 4 and the high frequency switching element 5 and the switching control circuit unit 6. Due to the start of the oscillation, a high frequency AC voltage is output to the first secondary winding S1 of the high frequency switching transformer 4 and the flyback output is output to the smoothing capacitor 8 by the rectifier diode 7 to generate the DC voltage. V1 is obtained. Similarly, by the rectifier diode 9 and the smoothing capacitor 10
The flyback output of is obtained as the DC voltage V2. 1
By applying the DC voltage V1 to the charging current control circuit unit 1 and the DC voltage V2 to the constant voltage circuit unit 15,
The charging current control circuit section of 17 supplies a predetermined charging current to the 17th output diode and the 14th output switching relay through the 17th output diode.
Then, the battery is supplied to the first secondary battery, and charging is started. 1
When the charging of the first secondary battery 7 progresses and the charge control circuit unit 12 detects the charging completion period, the output switching relay 14 switches and the charging of the second secondary battery 18 starts. . When the charging of the second secondary battery of 18 progresses and the charging control circuit unit of 12 detects the charging completion period, the charging current is switched to a minute current by the charging current control circuit unit of 10, and thereafter the charging current of 17 A minute current continues to be supplied to the first secondary battery or the second secondary battery of 18.

[0006]

However, in the above conventional structure, the first secondary winding S1 and the second secondary winding S2 of the high frequency switching transformer 4 are magnetically coupled, and First secondary winding S1 and second secondary winding S2
When the DC voltage V1 which is the flyback output of the first secondary winding S1 decreases because the respective flyback outputs are to be obtained from both the second secondary winding S2 and the second secondary winding S2.
DC voltage V2, which is the flyback output of
It was a characteristic that it decreased in proportion to. For this reason 18
When the voltage of the second secondary battery of 1 is 0 V due to over discharge, when the charging of the first secondary battery of 17 is completed and the charging of the second secondary battery of 18 is switched to, The DC voltage V1 which is the output of the secondary winding S1 is reduced to a voltage near 0V because the voltage of the second secondary battery of 18 is 0V, and at the same time, the output of the second secondary winding S2 is DC voltage V
Similarly, 2 also decreases. Since this DC voltage V2 is the power supply voltage of the 12 charging control circuit units,
All the charge control circuit parts of are reset and returned to the initial state, and the charging of the first secondary battery of 17 is started again. After that, since the first secondary battery 17 is in a charged state, the charging is completed in a short time, and the charging is switched to the charging of the second secondary battery 18 again. Since the voltage remains 0V, the above-mentioned operation is repeated, and the charging of the 17th secondary battery is started. After that, this repetition was continued, and as a result, there was a problem that the first secondary battery of 17 was continuously overcharged and the second secondary battery of 18 was not charged at all.

The present invention solves the above-mentioned conventional problems, and provides a charger for charging a secondary battery normally without causing any inconvenient operation even if the voltage of the secondary battery is 0V. The purpose is to

[0008]

In order to achieve this object, a battery charger of the present invention comprises a first diode connected to a first secondary winding of a high frequency switching transformer to obtain a DC output. A second diode connected to the secondary winding of the high-frequency switching transformer to obtain a flyback output and a DC output connected to the second secondary winding of the high-frequency switching transformer, and a forward output from the second secondary winding. It has the structure connected so that it may be obtained.

[0009]

With this configuration, the first secondary winding and the second secondary winding of the high frequency switching transformer do not interfere with each other even if the voltage of the battery is 0V. Therefore, even if the output voltage of the first secondary winding drops, the output voltage of the second secondary winding does not drop, so that the charging control circuit is not reset and the voltage of the battery is 0V. Even it can be charged normally.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the circuit block diagram shown in FIG. Since the circuit block diagram of the present embodiment shown in FIG. 1 has basically the same configuration as the conventional circuit block diagram shown in FIG. 2, the same components are designated by the same reference numerals.

In FIG. 1, 1 and 2 are AC input terminals and 3
Is a rectifying / smoothing circuit for rectifying / smoothing an AC input. Four
Is a high-frequency switching transformer, which has a first primary winding P1, a second primary winding P2, a first secondary winding S1, and a second secondary winding S2. Reference numeral 5 is a high frequency switching element, and 6 is a switching control circuit section. 7 is the first secondary winding S1 of the high frequency switching transformer 4
Is a rectifying diode that rectifies a high-frequency AC voltage output to a DC voltage to obtain a DC voltage, but has a polarity opposite to that of the first primary winding P1 in order to obtain a flyback output of the first secondary winding S1. Is connected to the terminal a of the first secondary winding S1. A smoothing capacitor 8 smoothes the DC voltage. Reference numeral 29 denotes a rectifier diode of the second secondary winding S2, which has a polarity opposite to that of the connection of the rectifier diodes of the first secondary winding S1 and the second secondary winding S2. It is connected to the terminal d of S2. 10 is the smoothing capacitor. 11 is a charging current control circuit unit, and 12
Is a charge control circuit section, 13 is an output diode for preventing a reverse current from the battery, and 14 is an output switching relay for switching the output to the two batteries. Reference numeral 15 is a constant voltage circuit unit that outputs a constant voltage that is a power supply voltage and a reference voltage of the charge control circuit unit 12 and the output switching relay 14. Reference numeral 16 is a photocoupler for feeding back the output fluctuation on the secondary side to the switching control circuit unit 6 on the primary side. Reference numeral 17 is a first secondary battery charged by a charging current output from the charger, and 18 is a second secondary battery.

The operation of the charger configured as above will be described below. First, an AC power supply is input to the AC input terminals 1 and 2 and converted into a DC voltage by the rectifying / smoothing circuit 3. By applying this DC voltage,
Oscillation is started by the high frequency switching transformer 4 and the high frequency switching element 5 and the switching control circuit unit 6. Due to the start of the oscillation, a high frequency AC voltage is output to the first secondary winding S1 of the high frequency switching transformer 4 and the flyback output is output to the smoothing capacitor 8 by the rectifier diode 7 to generate the DC voltage. V1 is obtained. Further, in the second secondary winding S2, by the rectifying diode of 29 and the smoothing capacitor of 10,
A forward output opposite to that of the first secondary winding S1 is obtained as the DC voltage V2. The DC voltage V1 is applied to the charging current control circuit unit 11 and the DC voltage V2 is applied to the constant voltage circuit unit 15 so that the charging current control circuit unit 11 supplies a predetermined charging current to the output diodes 13 and 14 Start supplying to the 17th secondary battery via the output switching relay,
Charging starts. When the charging of the first secondary battery 17 progresses and the charge control circuit unit 12 detects the charging completion period, the output switching relay 14 switches,
The charging of the second secondary battery 18 is started. And 18
When the charging of the second secondary battery of No. 1 progresses and the charge control circuit unit of 12 detects the charging completion period, the charge current is switched to a minute current by the charge current control circuit unit of 10, and thereafter the 17th The minute current continues to be supplied to the one secondary battery or the 18 second secondary battery.

In the charger according to the present embodiment, the first secondary winding S1 and the second secondary winding S2 of the high frequency switching transformer 4 are magnetically coupled to each other.
Since the flyback output is to be obtained from the secondary winding S1 and the forward output is to be obtained from the second secondary winding S2, the DC voltage which is the output of the first secondary winding S1 is obtained. V1 and the DC voltage V2 which is the output of the second secondary winding S2 do not interfere with each other. Therefore, 18
Even when the charge of the first secondary battery of 17 is completed and the charge of the second secondary battery of 18 is switched to in the state where the voltage of the second secondary battery of 0 is 0 V due to overdischarge, The DC voltage V1 that is the output of the first secondary winding S1 drops to a voltage near 0V because the voltage of the second secondary battery 18 is 0V, but the second secondary winding S1 The DC voltage V2, which is the output of the line S2, can maintain a predetermined voltage.
By maintaining this DC voltage V2, the charging completion detection circuit unit 12 is not reset,
The second secondary battery of No. 8 continues to be charged, its voltage gradually rises, and eventually the charging is completed.

As described above, according to the present embodiment, the rectifier diode 7 is connected to the terminal a of the high frequency switching transformer 4 to obtain the flyback output of the first secondary winding S1.
Connected to the second rectifier diode of the second secondary winding S2
By connecting to the terminal d in order to obtain the forward output of the first secondary winding S1, even if the direct current voltage 1 which is the output of the first secondary winding S1 decreases, the direct current voltage that is the output of the second secondary winding S2 Since 2 does not decrease, the battery having a voltage of 0 V can be normally charged without resetting the charge completion detection circuit unit.

[0015]

As described above, in the present invention, the first diode connected to the first secondary winding of the high frequency switching transformer to obtain a DC output is connected so as to obtain its flyback output, and the second diode An excellent charger capable of normally charging even a battery with a voltage of 0V by connecting a second diode connected to the secondary winding of the above-mentioned to obtain a DC output so as to obtain its forward output Can be realized.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a charger according to an embodiment of the present invention.

FIG. 2 is a circuit block diagram of a conventional charger.

[Explanation of symbols]

 1 AC input terminal 2 AC input terminal 3 Rectification / smoothing circuit 4 High frequency switching transformer 5 High frequency switching element 6 Switching control circuit section 7 Rectifier diode of first secondary winding 8 Smoothing capacitor of first secondary winding 9th Second secondary winding rectifier diode 10 Second secondary winding smoothing capacitor 11 Charging current control circuit section 12 Charging control circuit section 13 Output diode 14 Output switching relay 15 Constant voltage circuit section 16 Photocoupler 17 First Secondary battery 18 Second secondary battery 29 Second rectifier diode of secondary winding

Claims (1)

[Claims] 1. A high-frequency switching transformer having a first primary winding, a second primary winding, a first secondary winding, and a second secondary winding, and a high-frequency switching element. A switching control circuit unit, a first diode connected to the first secondary winding of the high frequency switching transformer to obtain a DC output, a first capacitor for smoothing the DC output, and a second secondary In a charger using a switching power supply circuit configured by a second diode connected to a winding to obtain a DC output and a second capacitor smoothing the DC output, the first diode is replaced by the first diode. A charger characterized in that the second diode is connected so as to obtain a flyback output, and the second diode is connected so as to obtain a forward output from the second secondary winding.