JP3071697B2 - Output current correction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output current correction method, and more particularly to an output current correction method for a power supply device for supplying power from a DC power supply to a load via a three-terminal regulator.

[0002]

2. Description of the Related Art Conventionally, a power supply device for supplying power to a load using a three-terminal regulator has a circuit configuration as shown in FIG. FIG. 2 is a circuit diagram showing a conventional technique. A capacitor C101 is connected in parallel to a DC power supply Vin, and the positive side of the DC power supply Vin is connected to an input terminal of a three-terminal regulator Z101. A series circuit of the resistors R101 and R102 is connected from the output terminal of the three-terminal regulator Z101 to the negative side of the DC power supply Vin, and the connection point between the resistors R101 and R102 is connected to the reference voltage terminal of the three-terminal regulator Z101. Have been. A smoothing capacitor C102 is connected between the output terminal of the three-terminal regulator Z101 and the negative side of the DC power source Vin, and a diode D10
1 through the power supply modules 102 to N having the same circuit.
Connected in parallel with the load.

In the above configuration, the DC power supply Vi
n is smoothed by the capacitor C101 and input to the input terminal of the three-terminal regulator Z101. The output voltage Vo of the power supply module 101 is as follows: Vo = (1 + R102 / R101) × Vref−Vf where Vref is a three-terminal regulator reference voltage and Vf is a forward voltage value of the diode D101. And the output voltage Vo smoothed by the capacitor C102.
Is output. The power supply module 101 is connected in parallel with the other power supply modules 102 to N having the same circuit, and supplies power to a load.

[0004]

In the prior art described above, the output voltage of each power supply module connected in parallel varies due to variations in the resistance, the reference voltage of the three-terminal regulator, the forward voltage value of the diode, and the like. Occurs. For this reason, the load current is supplied unevenly from the power supply module with the larger output voltage value, and if there is a power supply module that continues to supply a current that exceeds the rated value of the three-terminal regulator, the three-terminal regulator will be deteriorated or damaged. This causes a problem of lowering the reliability of the power supply module.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to control the output current of a power supply module that has supplied a large amount of current in a biased manner, and to deteriorate the three-terminal regulator. And to improve the reliability of the power supply module by preventing the power supply module from being damaged.

[0006]

[0007]

A first output current correction method according to the present invention is an output current correction method for a power supply module having a three-terminal regulator, wherein the power supply module is connected to one end of a DC power supply. A three-terminal regulator having an input terminal, a capacitor for smoothing the output of the three-terminal regulator, a first resistor connected across the output terminal of the three-terminal regulator and a reference voltage terminal, and the reference voltage terminal. A second resistor connected to the other end of the DC power supply; a third resistor connected in parallel with the second resistor;
A series circuit of a second transistor driving the first transistor, a series circuit of a second transistor and a fourth resistor, a fifth resistor having one end connected to an output terminal of the three-terminal regulator, And a diode connected between the other end of the fifth resistor and the load, the second transistor and the first transistor when an output current flowing through the fifth resistor exceeds a reference current value. Are turned on sequentially,
The output current value of the power supply module is controlled by sequentially turning off the second transistor and the first transistor when the output current value decreases to the reference current value.

A second output current correction method according to the present invention is an output current correction method for a plurality of power supply modules connected in parallel, wherein each of the power supply modules has an input terminal connected to one end of a DC power supply. Having a three-terminal regulator, a capacitor for smoothing the output of the three-terminal regulator,
A first resistor connected to both ends of an output terminal of the three-terminal regulator and a reference voltage terminal; a second resistor connected to the reference voltage terminal and the other end of the DC power supply; A series circuit of a third resistor and a first transistor connected in parallel with each other, a series circuit of a second transistor and a fourth resistor for driving the first transistor, and an output terminal of the three-terminal regulator. And a diode connected between the other end of the fifth resistor and the load, and when an output current flowing through the fifth resistor exceeds a reference current value. By sequentially turning on the second transistor and the first transistor, and sequentially turning off the second transistor and the first transistor when the output current value decreases to the reference current value, Power supply Wherein each of Yuru controls the output current value.

[0009]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention. A capacitor C1 is connected in parallel to a DC power supply Vin, and the positive side of the DC power supply Vin is connected to an input terminal of a three-terminal regulator Z1. It is connected. A series circuit of the resistors R1 and R2 is connected from the output terminal of the three-terminal regulator Z1 to the negative side of the DC power supply Vin, and the connection point between the resistors R1 and R2 is connected to the reference voltage terminal of the three-terminal regulator Z1. Have been. A smoothing capacitor C2 is connected between the output terminal of the three-terminal regulator Z1 and the negative side of the DC power supply Vin, and is connected in parallel with the power supply modules 2 to n having the same circuit via a diode D1, Connected to load.

Up to this point, this is the same as FIG. 2 described in the background art, but FIG.
4, R3 connected in parallel with resistor R2, and transistor Q
2 and a transistor Q1 and resistors R5, R6, and R7 constituting a driving circuit of the transistor Q2.

Next, the operation of the embodiment of the present invention will be described in detail with reference to FIG.

As shown in FIG. 1, a three-terminal regulator Z
N power supply modules 1 to n each having a power supply 1 are connected in parallel to supply power to a load. Now, when the current balance of the n power supply modules performing the parallel operation is lost and the current value output from the power supply module 1 increases, the output current is increased by the DC power supply Vi of the power supply module 1.
n to three-terminal regulator Z1, output current monitor resistor R
4 and the load via the diode D1 to the load, the voltage VR4 generated at the output current monitor resistor R4 also increases at the same time.

When the voltage VR4 becomes equal to or higher than the base saturation voltage of the transistor Q1, the transistor Q1 starts to turn on, and a current flows into the base of the transistor Q2 via the transistor Q1 and the resistor R6.
2 also starts to turn on. Here, the base saturation voltage value of the transistor Q1 is equal to or less than the rated current value of the three-terminal regulator Z1, and the voltage VR of the output current monitoring resistor R4 at a reference current value such as the rated output current of the power module 1 is set.
4.

Normally, when the voltage VR4 is lower than the base saturation voltage value of the transistor Q1, the output voltage Vo is equal to the resistance R1
And the resistance R2 are controlled as follows.

Vo = (1 + R2 / R1) × Vref−Vf where Vref is a three-terminal regulator reference voltage, and Vf is a forward voltage value of the diode D101.

However, when the transistor Q2 is turned on, a current flows in a series circuit of the transistor Q2 and the resistor R3. Therefore, the series circuit of the transistor Q2 and the resistor R3 is connected in parallel to the resistor R2. Is controlled as in the following equation.

Vo ′ = (1 + R2 ′ / R1) × Vref−Vf where R2 ′ = α × R2, α = F (1 / output current) and 0
<Α <1.

As a result, the output voltage Vo 'starts to decrease,
Although the output current also decreases, the output current continues to decrease until the voltage VR4 of the output current monitor resistor R4 becomes less than the base saturation voltage value of the transistor Q1, and stabilizes the output current to the reference current value.

By the above operation, the output current of the power supply module that has supplied a large amount of output current is reduced, and the output current balance with the other power supply modules operating in parallel is improved.

In the above-described embodiment of the present invention, the power supply module is operated in parallel operation.
Obviously, the present invention can be applied to an isolated power supply module.

[0022]

As described above, according to the present invention,
In each power supply module that has a three-terminal regulator and operates in parallel, the output current of the power supply module that supplied a large amount of current is controlled to prevent deterioration and damage of the three-terminal regulator, This has the effect of improving reliability.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional technique.

[Explanation of symbols]

 1 to n power supply module C1, C2 capacitor D1 diode Q1, Q2 transistor R1, R2, R3, R5, R6, R7 resistor R4 output current monitor resistor Vin DC power supply Vo output voltage Z1 three-terminal regulator

Claims (2)

(57) [Claims] An output current correction method for a power supply module including a three-terminal regulator, wherein the power supply module has a three-terminal regulator having an input terminal connected to one end of a DC power supply, and an output of the three-terminal regulator. And a first terminal connected to both ends of the output terminal and the reference voltage terminal of the three-terminal regulator.
A second resistor connected to the reference voltage terminal and the other end of the DC power supply, a third resistor and a first transistor connected in parallel with the second resistor, and a series circuit of: A series circuit of a second transistor for driving the first transistor and a fourth resistor, a fifth resistor having one end connected to the output terminal of the three-terminal regulator, and a second end of the fifth resistor. A diode connected between the second transistor and the first transistor when an output current flowing through the fifth resistor exceeds a reference current value. An output current correction method, wherein the output current value of the power supply module is controlled by sequentially turning off the second transistor and the first transistor when the current value decreases to the reference current value. 2. An output current correction method for a plurality of power supply modules connected in parallel, wherein each of the power supply modules has a three-terminal regulator having an input terminal connected to one end of a DC power supply, and the three-terminal regulator. A first resistor connected to both ends of the output terminal and the reference voltage terminal of the three-terminal regulator, and a second resistor connected to the reference voltage terminal and the other end of the DC power supply. A resistor, a series circuit of a third resistor and a first transistor connected in parallel with the second resistor, a series circuit of a second transistor and a fourth resistor for driving the first transistor, Is a fifth resistor connected to the output terminal of the three-terminal regulator;
A diode connected between the other end of the resistor and the load, and when the output current flowing through the fifth resistor exceeds a reference current value, the second transistor and the first transistor are connected to each other. Sequentially turning on, and sequentially turning off the second transistor and the first transistor when the output current value decreases to the reference current value,
An output current correction method, wherein each of the power supply modules controls an output current value.