JPH0556112B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a DC stabilized power supply device for supplying a stabilized DC voltage to a load. The present invention relates to a DC stabilized power supply device equipped with a remote sense circuit that controls the output voltage so that the voltage across both ends is constant.

(Prior Art) FIG. 2 is a block diagram showing an example of a conventional DC stabilized power supply device of this type. here,
A case where a switching power supply is used will be exemplified. In the figure, 1 is a rectifier and smoothing circuit, 2 is a transformer, 3 is a switch element that switches the DC voltage obtained from the rectifier and smoothing circuit 1 and supplies it to the primary coil of the transformer 2, and 4 is a signal obtained to the secondary coil of the transformer 2. 5 is the _DC output voltage obtained at the output terminal 6.
This is a control circuit that controls ON/OFF of the switch element 3 so that e ₀₁ becomes a constant voltage corresponding to the reference voltage Vref. 7 is a load to which the DC output voltage e ₀₁ is supplied.

In the DC stabilized power supply device configured as described above, when the load 7 is installed close to the output terminal 6, the accurately stabilized DC power e ₀₁ is supplied to the load 7; If the load 7 is installed far from the output terminal 6, a voltage drop determined by the resistance of the line leading to the load 7 and the load current will affect the voltage, making it impossible to provide a stable voltage supply. arise.

In order to eliminate such problems, the control circuit 5 detects the voltage e ₇ across the load 7 via the sense line 8 indicated by the broken line, and maintains the voltage of the load voltage e ₇ at a constant level corresponding to the reference voltage Vref. All you have to do is control it so that the voltage is the same.

(Problems to be Solved by the Invention) However, when detecting the voltage e ₇ across the load 7 via the sense line 8 shown by the broken line, if the connection of the sense line 8 is shifted or disconnected,
Normally, the control circuit 5 determines that an overvoltage has occurred and performs a control operation to reduce the output voltage e ₀₁ to zero. Therefore, the disconnection accident of sense line 8 was caused by
There was a problem in that the voltage supply to the load 7 was stopped.

The present invention was made in view of these problems, and its purpose is to detect the voltage across the load,
This is a DC stabilized power supply that controls this voltage to a constant voltage, and is capable of supplying a stabilized DC voltage to the load even if an accident such as a sense line disconnection occurs. Our goal is to provide the following.

(Means for Solving the Problems) The present invention, which solves the above-mentioned problems, includes inputting a voltage corresponding to the output voltage generated at the output terminal as a feedback voltage, and controlling the output voltage to be a constant voltage. A DC stabilized power supply device equipped with a control circuit that divides the output voltage generated at the output terminal to obtain a feedback voltage, and a feedback circuit that includes a plurality of resistors to obtain a feedback voltage, and a pair of sense lines that are connected to each other and guide the voltage across the load; a plurality of resistors that are connected to the other ends of the pair of sense lines that divide the voltage across the load; and a plurality of resistors that constitute the feedback circuit. A series circuit consisting of a resistor and a transistor connected in parallel to the sense line converts the divided voltage into a current signal by a plurality of resistors connected to both ends of the sense line, and converts the base current of the transistor into a current signal. A DC stabilized power supply device comprising: a current control element for controlling the feedback voltage, and correcting the feedback voltage within a predetermined range by a voltage guided through a sense line.

(Example) FIG. 1 is a configuration and connection diagram showing an example of a device according to the present invention. In this figure, parts corresponding to those in the circuit of FIG. 2 are designated by the same reference numerals.

In the figure, 9 is a remote sense circuit that inputs the voltage across the load 7 (load voltage) _e7 via the sense line 8, and 10 is the output voltage generated at the output terminal 6.
This circuit feeds back the voltage V _FB corresponding to e ₀₁ to the control circuit 5, and is composed of resistors R ₁ , R ₂ , and R ₃ . In the device of the present invention, the feedback voltage V _FB to the control circuit 5 is corrected within a predetermined range by the output of the remote sense circuit 9.

In the remote sense circuit 9, _Q1 is a transistor whose collector and emitter are connected to one ends of a resistor _R1 and a resistor _R2 via resistors _R4 and _R5 , respectively. U1 is a current control element that controls the current flowing through it according to a voltage signal, and TI's TL431 is used here. _R7 , _R8 ,
R ₉ and R ₁₀ are resistors connected in series to the sense line 8, and a voltage Vs corresponding to the voltage e ₇ across the load 7 is obtained at the common connection point of the resistor R ₈ and the resistor R ₉ . this voltage
Vs is applied to the control terminal 91 of the current control element U1.

The operation of the apparatus configured in this way will be explained next.

The control circuit 5 controls the output voltage generated at the output terminal 6.
Divide the voltage of e ₀₁ and input the value of the feedback voltage V _FB determined by the resistors R ₁ , R ₂ , and R ₃ , and set the switch element 3 so that this feedback voltage V _FB becomes a constant voltage corresponding to the reference voltage Vref. Control on/off. When the load 7 is connected to the output terminal 6 via the line l, the voltage e ₇ across the load 7 and the load current I ₀
Then, a voltage drop I ₀ ·(Rl ₁ +Rl ₂ ) occurs due to the wire resistances Rl ₁ and Rl ₂ of the line I, and the output voltage becomes lower than the output voltage e ₀₁ . The voltage e ₇ across the load 7 is the sense line 8
is added to the series circuit of resistors R ₈ to R ₁₀ through e ₇
A voltage Vs' corresponding to the current control element U1 is applied to the control terminal 91 of the current control element U1. Here, current control element U1
When the voltage Vs applied to the control terminal 91 exceeds a predetermined voltage ΔVs, the current I flowing there, and therefore the base current I _B of the transistor Q, is controlled within a predetermined range according to the deviation between Vs and ΔVs. Control.
When the base current I _B of the transistor Q changes, the collector-emitter voltage V _CE of the transistor Q also changes, and the voltage Vm at the connection point between the resistors R ₂ and ₃ changes. As a result, the feedback voltage V _FB to the control circuit 5 is corrected, and the control circuit 5 changes the output voltage e ₀₁ so as to compensate for the voltage drop due to the wire resistance of the line I, and the voltage across the load 7
e ₇ is maintained at a constant value regardless of the magnitude of the load current I ₀ .

Here, if an accident such as disconnection or disconnection of the sense line 8 occurs for some reason, the control voltage Vs of the current control element U1 becomes zero,
The current I flowing into the current control element U1 side, and therefore the base current I _B of the transistor Q, becomes zero. As a result, the control circuit 5 inputs the uncorrected feedback voltage V _FB corresponding to the output voltage e ₀₁ of the output terminal 6 and performs a control operation so that the output voltage e ₀₁ generated at the output terminal 6 is maintained at a constant value. Let's do it. Therefore, the voltage supply to the load 7 continues, although the voltage e ₇ at both ends is affected by the voltage drop due to the wire resistance and the load current.

In addition, in the above embodiment, the case where the present invention is applied to a switching power supply was explained as an example.
The present invention can be similarly applied to other types of stable power supply devices.
In addition, the configuration of the remote sense circuit may include other circuits than those shown in the drawings.

(Effects of the Invention) As explained above, according to the present invention, the voltage across the load can be maintained constant, and
Even if an accident such as a disconnection of the sense line occurs, voltage can be supplied to the load, and a highly reliable stabilized power supply device can be realized.

That is, in the present invention, a series circuit consisting of a resistor and a transistor is connected in parallel to a plurality of resistors for dividing the output voltage generated at the output terminal to obtain a feedback voltage, and the base current of the transistor is One of the features of the configuration is that the correction is made in accordance with the voltage across the load led through the sense line. With this configuration, the feedback voltage VFB is
As shown in equation (1), even if an accident occurs where the sense line 8 is disconnected, the resistor R1,
The voltage does not exceed a predetermined voltage determined by R2, etc., and the stabilizing operation can be continued.

VFB={R2/(R1+R2)}(e ₀₁ −Vm) ...(1) However, e ₀₁ is the voltage generated at output terminal 6, Vm is the voltage obtained at the common connection point of resistors R2 and R3, and transistor Q1 Letting the collector-emitter voltage of be VCE, it is shown by equation (2).

Vm=[R3{e ₀₁ (R1+R2+R4+R5−VCE(R1+R2)}]/
{(R4+R5)(R1+R2+R3)}……(2)

[Brief explanation of the drawing]

Fig. 1 is a configuration and connection diagram of the device according to the present invention;
The figure is a configuration and connection diagram of a conventional device. 5... Control circuit, 6... Output terminal, 7... Load, 8... Sense line, 9... Remote sense circuit, 10... Feedback circuit.

Claims (1)

[Claims] 1. A DC stabilized power supply device comprising a control circuit 5 that inputs a voltage corresponding to the output voltage generated at the output terminal 6 as a feedback voltage and controls the output voltage to be a constant voltage. , a plurality of resistors R1 for dividing the output voltage generated at the output terminal 6 to obtain a feedback voltage;
A feedback circuit 10 consisting of R2 and R3, a pair of sense lines 8 connected to both ends of the load 7 connected to the output terminal 6 and leading the voltage across the load, and a pair of sense lines 8 connected to the other end of the pair of sense lines. A plurality of resistors R7 to R10 that divide the voltage across the load 7
A series circuit consisting of a resistor and a transistor Q1 connected in parallel to the plurality of resistors constituting the feedback circuit, and a plurality of resistors R7 to R10 connected to both ends of the sense line. and a current control element U1 that converts the divided voltage into a current signal and controls the base current of the transistor, and corrects the feedback voltage within a predetermined range by a voltage led through the sense line. Characteristic DC stabilized power supply device.