JPH05122830A - Output protective function confirming circuit - Google Patents

Abstract

PURPOSE:To make it possible to confirm the operation of output protective function at the start of DC power supply by feeding DC output after confirmation that overvoltage detection and undervoltage detection are performed normally. CONSTITUTION:DC output from a smoothing circuit 5 is fed to an output monitoring circuit 6 and a photocoupler PC0 is turned ON when an undervoltage detection level is exceeded. Upon turn ON of a thyristor Th, a photocoupler PC1 functions to confirm the operation of the thyristor Th. Upon turn ON of the photocoupler PC1 in an output protection control circuit 7, the photocoupler PC1 in a protective operation confirming/starting circuit 10 is turned ON and a relay A functions. Relay B functions through contact a<2> of the relay A and relay TST is recovered through contact b<2>. Upon recovery of the relay TST, contact tst<1> thereof opens to recover a relay P. Consequently, the photocoupler PC1, photothyristors PTh and the thyristor Th in the output protection control circuit 7 are entirely turned OFF.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for confirming an output protection function of a DC power supply device. Many DC power supply devices such as DC output converters have an overvoltage protection function and a low voltage detection function as standard functions for the output in order to prevent overvoltage or low voltage from being output as DC output. ..

However, in the case of a general power supply device,
These functions are only inspected by the manufacturer at the time of shipment, and it is difficult to send out overvoltage or low voltage after they are actually used, so it is not possible to confirm the operation of these functions. It can be said that there are few. Therefore, these output protection functions operate only when an overvoltage or low voltage of the output actually occurs, but since the frequency of occurrence is low, these output protection functions have few opportunities to operate, and when an abnormality occurs The reality is that there are some uncertainties about whether or not it will operate reliably.

For this reason, there is a demand for a method that can easily confirm the operation of the output protection function in normal times.

[0004]

2. Description of the Related Art FIG. 4 is a circuit block diagram of a conventional DC output converter. When DC power (hereinafter referred to as input power) is input to the DC output converter shown in FIG. 4, the auxiliary power supply circuit (AUX-POW) 2 operates, and the switch control circuit (CONT-IC) 1 and the like are supplied with operating power. Supply.

The switch control circuit 1 operates when a low-level potential (for example, 0 potential) is connected to the X ₂ terminal while power is supplied. When the operating power is supplied as described above, the resistor R is connected to the X ₂ terminal.
_A voltage is applied via ₁ and R ₄ , but at this time the resistance R ₁
The capacitor C ₂ connected in series with is charged, and the X ₂ terminal is at a low potential until the capacitor C ₂ is charged to some extent, so that the switch control circuit 1 starts its operation.

A pulse is output from the Y terminal by the operation of the switch control circuit 1, and the field effect transistor (hereinafter referred to as FET) Q ₀ is switched via the transistors Q ₁ and Q ₂ . The pulse induced on the secondary side of the transformer (T) 3 by switching the input power by the FET Q ₀ is rectified and smoothed by the smoothing circuit 5, and is sent to the outside as a DC output.

The voltage of the DC output is monitored for overvoltage and low voltage by the output monitoring circuit 16. However, the DC output output when the input voltage is input is not the stipulated voltage immediately. , It rises after a certain period of time, so the low voltage detection value is reached first.

The detection of the low voltage is carried out by a series circuit of a resistor R _7, a photocoupler PC ₀ and a Zener diode DZ ₀ indicated by LV in the output monitoring circuit 16, and the DC output voltage is the Zener voltage in the Zener diode DZ ₀ , That is, when the voltage reaches a value higher than the low voltage detection value, the operating current flows through the photocoupler PC ₀ .

As a result, the photocoupler PC ₀ in the output protection control circuit 17 is turned on, and the X of the switch control circuit 1 is turned on.
_The switch control circuit 1 continues to operate because the _two terminals have a low potential. After that, the DC output rises to a normal voltage and is supplied to the outside. When the photocoupler PC ₀ is turned on, the charging of the capacitor C ₂ is stopped.

In the above, when the photocoupler PC ₀ is not turned on even when the input power is input, that is, when the voltage of the DC output does not rise to the low voltage detection value, the charging of the capacitor C ₂ proceeds, Since the voltage via the resistors R _{1 and} R ₄ is applied to the X ₂ terminal of the switch control circuit 1, the switch control circuit 1 stops its operation, and a circuit (not shown) displays the low voltage detection and displays the input power. Cutting is performed.

Further, since the DC output when the output voltage by something like some reasons after reaching the normal voltage is below the low voltage detection value photocoupler PC ₀ turned off, similarly to the capacitor C ₂ Is charged, switch control circuit 1
Since a voltage is applied to the X ₂ terminal of the switch control circuit 1, the switch control circuit 1 stops its operation.

Next, the case where the DC output is overvoltage will be described. The overvoltage is detected by the circuit indicated by OV in the output monitoring circuit 16. DC output is resistance R _8, R _9, R ₁₀
The join to the series circuit, but divided voltage to the connection point of the resistors R ₉ and R ₁₀ appears, the shunt regulator IC is turned on when the divided voltage exceeds the value set as the overvoltage detection value. When the shunt regulator IC is turned on, an operating current flows through the photothyristor PTh connected in series with the shunt regulator IC.

As a result, the photothyristor PTh in the output protection control circuit 17 is turned on, so that the X ₁ terminal of the switch control circuit 1 becomes 0 potential. Switch control circuit 1 is X
_{Since the} operation is stopped when the ₁ terminal is at 0 potential, the output from the Y terminal is stopped and the sending of the DC output is also stopped. In this state, a circuit (not shown) displays overvoltage detection and cuts off the input power to prevent the output portion from sending the overvoltage.

As described above, the protection against the overvoltage output of the DC output converter and the detection of the low voltage are performed, but it is confirmed by the manufacturer's inspection at the time of shipping that the output protection operation is surely performed. However, since it is difficult for the user to generate a low voltage or an overvoltage after the user has started using the device, the actual situation is that the operation check is hardly performed.

Therefore, for example, even if an abnormality occurs in the photocoupler PC ₀ or the photothyristor PTh, it becomes latent, and as a result, a serious problem may occur when an overvoltage or a low voltage actually occurs.

[0016]

The output protection function provided in a power supply device such as a DC output converter has been conventionally known.
After the operation is confirmed by the manufacturer, there is no possibility that the operation will be confirmed, so there is a possibility of failure.
When an overvoltage or a low voltage actually occurred, there was a possibility that it would be a big problem.

An object of the present invention is to confirm the operation of the output protection function when the DC power supply device is started.

[0018]

FIG. 1 is a basic block diagram of the present invention. In the figure, 1 is a transformer 3 to which input power is applied.
A switch control circuit for switching a switch element 4 connected in series with the switch control circuit 2, an auxiliary power supply circuit that is activated by input power and supplies operating power to the switch control circuit 1, a transformer 4, a switch element 5, and a switch 5. It is a smoothing circuit that rectifies and smoothes the voltage induced on the secondary side of the transformer 3 when the element is switched and sends it as a DC output.

Reference numeral 6 denotes an output monitoring circuit for monitoring the DC output to detect an overvoltage or low voltage, and 7 denotes output protection by controlling the switch control circuit 1 when the output monitoring circuit detects an overvoltage or a low voltage. It is an output protection control circuit for performing.

Reference numeral 8 is an operating power supply opening / closing means for opening and closing the supply of operating power supply from the auxiliary power supply circuit 2 to the switch control circuit 1, and 9 is an output opening / closing means for closing the output portion of the DC output during operation to send out the DC output. It is a means.

Reference numeral 10 controls the operating power supply opening / closing means 8 and the output opening / closing means 9, operates the switch control circuit 1 at the time of input of input power, and detects the overvoltage of the output monitoring circuit 6 at a normal output voltage or less. Control, the output monitoring circuit 6 and the output protection control circuit 7 cooperate with each other to confirm the detection of the overvoltage, and then the operation of the switch control circuit 1 is stopped to confirm the detection of the low voltage. It is a protection operation confirmation starting means for later closing the output opening / closing means 9 to restart the switch control circuit 1 and start sending the DC output.

[0022]

In FIG. 1, when the DC power is input, the auxiliary power supply circuit 2 and the protection operation confirmation starting means 10 start the operation. First, the protection operation confirmation starting means 10 is the operation power supply opening / closing means 8.
The auxiliary power supply circuit 2 supplies operating power to the switch control circuit 1.

As a result, the switch control circuit 1 operates,
When the switching element 4 is switched, the input power is interrupted and a pulse is induced on the secondary side of the transformer 3. The smoothing circuit 5 rectifies and smoothes this pulse, and outputs a DC voltage.

At this time, since the output switching means 9 is open, the DC output is not sent to the outside, but is input to the output monitoring circuit 6 and the output voltage is monitored. On the other hand, the protection operation confirmation starting means 10 changes the overvoltage detection value of the overvoltage detection part (not shown) in the output monitoring circuit 6 so that the protection operation confirmation starting means 10 operates at a normal output voltage or less.

When the DC output from the smoothing circuit 5 rises, the output monitoring circuit 6 first confirms that the detection value of the low voltage has been exceeded and notifies the output protection control circuit 7 of the switch control circuit 1 at this point. The operation continues as it is.

Although the DC output from the smoothing circuit 5 is further increased by continuing the operation of the switch control circuit 1,
Since the previously changed overvoltage detection value is reached before the normal voltage is reached, the output monitoring circuit 6 detects this overvoltage and notifies the protection operation confirmation starting means 10 via the output protection control circuit 7.

Upon receiving the notification that the overvoltage has been detected, the protection operation confirmation starting means 10 opens the operation power supply opening / closing means 8 to stop the supply of the operation power to the switch control circuit 1 and temporarily stop the operation of the switch control circuit 1. .. As a result, the output voltage of the DC output from the smoothing circuit 5 decreases, and the output monitoring circuit 6 detects a low voltage.

When the detection of the low voltage is transmitted to the protection operation confirmation starting means 10 through the output protection control circuit 7, the protection operation confirmation starting means 10 closes the output opening / closing means 9 and smooths the circuit 5.
Then, the operating power supply opening / closing means 8 is closed and the supply of operating power supply to the switch control circuit 1 is restarted.

As a result, the switch control circuit 1 restarts switching of the switch element 4, and the DC output is output from the smoothing circuit 5. However, since the output opening / closing means 9 is closed this time, the DC output is output to the outside. Transmission is started.

As described above, in FIG. 1, since the DC output is sent after confirming that the overvoltage detection and the low voltage detection are normally performed before sending the DC output to the outside, the power supply device is activated each time. The normality of the output protection function will be confirmed.

[0031]

FIG. 2 is a circuit block diagram of an embodiment of the present invention, FIG.
Is a time chart of an embodiment of the present invention.

Throughout the drawings, the same symbols represent the same objects, and 1 represents an IC (CONT-) which constitutes a switch control circuit.
IC), 2 is an auxiliary power supply circuit (AUX-POW), 3 is a transformer (T), 5 is a smoothing circuit, 6 is an output monitoring circuit, 7 is an output protection control circuit, 10 is a protection operation confirmation activation circuit, and 11 is an input. A power terminal 12 is a DC output terminal.

A, B, C, P and TST are relays.
(Winding), a¹~ Tst³Are relays A to TST
It is a point. C₀~ C_FourIs a capacitor, D₀Is Daio
Do, DZ _0,DZ₁Is a Zener diode, L₀Is cho
Coil, IC for shunt regulator, PC_0,PC₁
Is a photo coupler, PTh is a photothyristor, Q₀Is electric
Field effect transistor (FET), Q_1,Q₂Is Transis
T, R₀~ R₁₁Is a resistance and Th is a thyristor.

The FET Q ₀ realizes the switch element 4 of FIG. 1, the relay contact p ² realizes the operating power supply opening / closing means 8 of FIG. 1, and the relay contacts c ³ and c ⁴ realize the output opening / closing means 9 of FIG. is there.

The operation of FIG. 2 will be described below, but FIG. 3 is also used for the description, and the symbols a to i of the relevant portions of FIG. 3 are described in parentheses. In the internal circuits of the output monitoring circuit 6 and the output protection control circuit 7, the description of the parts that perform the same operation as in the conventional technique of FIG. 4 is omitted to avoid duplication.

In FIG. 1, when the input power is applied to the input power terminal 11 (a), the auxiliary power supply circuit 2 is activated and the operating power is output, but this output is switch controlled because the contact p ² is open. It is not supplied to the circuit 1, and the switch control circuit 1 does not operate (D, E).

Further, the relay TST is operated by the input power, the contact tst ¹ is closed, and the relay P is operated (ta, yo).
As a result, the contact p ² is closed, and the operating power is supplied, so that the switch control circuit 1 operates and outputs a pulse from the Y terminal (e).

[0038] The pulse input power because switching the FETs Q ₀ through the transistor Q _1, Q ₂ and the resistor R ₀ is intermittent, induces a pulse on the secondary side of the transformer 3. The induced pulse is rectified and smoothed by the smoothing circuit 5 and output as a direct current output, but the output voltage rises over some time (b). The smoothing circuit 5
Since the internal circuit of is the same as that of FIG. 4, detailed description thereof is omitted in FIG.

The DC output from the smoothing circuit 5 is input to the output monitoring circuit 6, but when the low voltage detection value described with reference to FIG. 4 is exceeded, the photocoupler PC ₀ is turned on as in FIG. 4 (b, G). Further, in the output protection control circuit 7 in which the contact p ² is closed and the supply of operating power is started, the capacitor C ₂
However, since the photo coupler PC ₀ is turned on, the terminal voltage of the capacitor C ₂ does not rise (L).

When the photocoupler PC ₀ of the output protection control circuit 7 is turned on, the 0 level potential is applied to the X ₂ terminal of the switch control circuit 1, so that the switch control circuit 1 continues to operate and the smoothing circuit 5 operates. The DC output voltage rises further (b).

On the other hand, in the output monitoring circuit 6, the relay TS is first
When T operates, the resistor R ₉ is short-circuited by the contact tst ³ and the shunt regulator IC is set to operate at a normal voltage or less. Therefore, the shunt regulator 5 does not reach the normal voltage before the DC output from the smoothing circuit 5 reaches the normal voltage. The regulator IC operates (B, F).

When the photothyristor PTh operates by the operation of the shunt regulator IC, the output protection control circuit 7
Since 0 potential is sent to the X ₁ terminal of the switch control circuit 1, the switch control circuit 1 stops its operation (re,
E).

As a result, the voltage of the DC output from the smoothing circuit 5 decreases, so that the shunt regulator IC and the photocoupler PC ₀ of the output monitoring circuit 6 are turned off (b,
F, G). Since the operation of the photothyristor PTh is held in the output protection control circuit 7, it does not turn off at this point (i).

When the photocoupler PC ₀ is turned off, the voltage at the connection point between the resistors R ₁ and R ₄ rises in the output protection control circuit 7, so that the charging of the capacitor C ₂ starts, but this time it rises to a sufficient terminal voltage. Therefore, the Zener voltage of the Zener diode DZ ₁ is exceeded, the gate voltage of the thyristor Th rises to the operating voltage, and the thyristor Th is turned on (g,
Le, Nu).

Turning off the photocoupler PC ₀ means detecting a low voltage, and turning on the thyristor Th applies 0 potential to the X ₁ terminal of the switch control circuit 1 through the diode D ₀ to control the switch. Since the operation of the circuit 1 is stopped, it can be confirmed that the low voltage detection is normal when the thyristor Th is turned on.

However, in this case, since the photothyristor PTh is kept in the ON state as described above, the X ₁ terminal of the switch control circuit 1 is already at 0 potential, and the switch control circuit 1 remains inactive. It becomes (e).

Therefore, in the circuit of FIG. 1, when the thyristor Th is turned on, the photocoupler PC ₁ inserted in series is connected.
To confirm the operation of the thyristor Th. When the photo coupler PC ₁ of the output protection control circuit 7 is turned on, photocoupler PC ₁ protection operation check start circuit 10 is turned on, relay A is operated (Ji, Wo). The relay A holds itself by the contact a ¹ and operates the relay B by the contact a ² (wa).

The relay B holds itself by the contact b ¹ and restores the relay TST by the contact b ² . When the relay TST is restored, the contact tst ¹ is opened and the relay P is restored (Y). As a result, when the contact p ² opens, the operating power supply from the auxiliary power supply circuit 2 is cut off.
The photocoupler PC ₁ , the photothyristor PTh, and the thyristor Th in the output protection control circuit 7 are all turned off (ch, r, n).

In the above operation, since the thyristor Th is turned off after the contact p ² is opened, the switch control circuit 1 which has stopped the operation because the terminal X ₁ is set to a low potential by the thyristor Th. Will never work with (e).

Since the contact p ¹ is restored by the restoration of the relay P, the relay C operates, the output of the smoothing circuit is connected to the DC output terminal 12 by the contacts c ³ , c ⁴ , and the relay P is made by the contact c ^2. To operate again (K, Y). Since the operation of the relay is larger than the on / off time of the semiconductor element or the like, it takes some time from the recovery of the relay P to the restart thereof, and the thyristor Th and the like are recovered (off) during this time. You can secure enough time to do it.

Due to the operation of the relay C and the re-operation of the relay P, the DC output converter of FIG. 2 becomes the same as the state where the input power is supplied to the DC output converter of FIG. 4, and the normal DC output operation is started. That is, the relay P operates and the contact p
^The switch control circuit 1 operates again when the operating power is supplied by ² to start sending the DC output. However, since the contacts c ³ and c ⁴ are closed this time, the DC output is external from the DC output terminal 12. Sent to (Ka, Yo, Ho, Ro, Ha).

The output monitoring circuit 6 monitors the DC output from the smoothing circuit 5 and confirms that the low voltage detection value has been exceeded to continue the output, as in the previous time, but this time the contact tst ³ is not closed. Therefore, the shunt regulator IC does not operate unless the DC output actually becomes an overvoltage, and the DC output reaches the normal voltage and is continuously output as it is.

During transmission of DC output, relays A, B, C and P
Keeps being held by the input power (W, W, K, Y) and recovers when the input power is cut off (not shown in FIG. 3).
Therefore, the confirmation of the output protection operation is performed only once each time the input power is turned on.

Although the embodiment of the present invention has been described above with reference to FIGS. 2 and 3, FIGS. 2 and 3 merely show one embodiment of the present invention, and the present invention is shown in FIGS. It is needless to say that the internal circuit of each component is not limited to the ones shown in FIG.

For example, it is obvious that the circuit of FIG. 2 can be applied to an AC-DC converter that uses DC power as input power or uses AC power by adding a rectifier to the input side.

Further, the protection operation confirmation start-up circuit 10 of FIG. 2 is transmitting the DC output to the outside, and the four relays A, B, C and P are provided.
However, it is easy to reduce the number of self-holding relays. Further, in FIG. 2, the protection operation confirmation starting circuit 10 is configured by using only the relay, but the effect of the present invention does not change even if it is configured by using an element other than the relay.

[0057]

As described above, according to the present invention,
In a DC power supply device such as a DC output converter, it is possible to check the operation of the output overvoltage protection function and the undervoltage detection function each time the input power is turned on.In particular, by changing the overvoltage detection value, it is possible to check the conventional operation. Since the operation of the overvoltage protection function, which has been difficult, can be easily confirmed, it greatly contributes to the improvement of the reliability of the power supply device.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention.

FIG. 2 is a circuit block diagram of an embodiment of the present invention.

FIG. 3 is a time chart of an example of the present invention.

FIG. 4 is a circuit block diagram of a conventional technique.

[Explanation of symbols]

 1 Switch Control Circuit 2 Auxiliary Power Supply Circuit 3 Transformer 4 Switch Element 5 Smoothing Circuit 6 Output Monitoring Circuit 7 Output Protection Control Circuit 8 Operating Power Supply Opening / Closing Means 9 Output Opening / Closing Means 10 Protection Operation Confirmation Starting Means

Claims (1)

[Claims] 1. An auxiliary power supply circuit activated by input power
The switch control circuit (1) supplied with operating power from (2) switches the switch element (4) connected to the primary side of the transformer (3) to smooth the secondary side of the transformer (3). The output protection control circuit (7) outputs the DC output through the circuit (5), and when the output monitoring circuit (6) detects an overvoltage or an undervoltage of the DC output, the switch control circuit (1) In the DC power supply device for controlling the output by controlling the operation power supply, an operating power supply opening / closing means (8) for opening and closing the supply of the operating power supply from the auxiliary power supply circuit (2) to the switch control circuit (1)
An output opening / closing means (9) for closing the output portion of the DC output during operation and sending out the DC output; controlling the operating power supply opening / closing means (8) and the output opening / closing means (9) to Switch control circuit when input (1)
The output monitoring circuit (6) is controlled so that the overvoltage detection is performed below the normal output voltage, and the overvoltage detection is performed by the cooperative operation of the output monitoring circuit (6) and the output protection control circuit (7). After confirming the above, the operation of the switch control circuit (1) is stopped and the detection of low voltage is confirmed, and then the output switching means (9) is closed and the switch control circuit (1) is restarted, An output protection function confirmation circuit comprising a protection operation confirmation start-up means (10) for starting transmission of DC output, and confirming the output protection function when the power supply is started.