JPH04334925A - Power feeding and shutting-off system - Google Patents

Abstract

PURPOSE:To provide a power feeding and shutting-off system for shutting off an output against an overload condition and automatically starting again feeding of power source when a normal load condition is recovered. CONSTITUTION:A power feeding apparatus which feeds power source in direct to a load 2 from a power converter 1 comprises an output shutting-off circuit 3 for shutting off power source to a load and a voltage detecting means 4 for outputting an output of the power converter 1, when the output shutting-off circuit 3 shuts off power source, by bypassing the output shutting-off circuit 3 via an impedance 5 and a diode 6 and also comparing a voltage output to the load with a preset voltage to output a comparison result as a control signal. Moreover, an output shutting-off control means 7 is also provided for controlling the output shutting-off circuit 3 to shut-off an output when a control signal indicating that a voltage output to a load is lower than a preset voltage is input from the voltage detecting means 4 and to feed a power source to the load when the control signal indicating that a voltage output to the load is higher than the preset voltage is input.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply cutoff system for cutting off output when an overload occurs. In recent years, power supply devices that supply DC power to communication devices and the like have been widely used. In these power supply devices, various protection circuits are used to protect the power supply device when an overload condition occurs in the output.

However, the conventional overload protection method for power supply equipment is to cut off the load side using a protection element such as a fuse or breaker when an overload occurs, and the overload condition is recovered. However, the power supply could not be restarted without manual intervention.

[0003]Also, some methods have been used in which the power supply section is allowed to withstand an overload condition, but this method has the disadvantage that the device becomes large and expensive. An object of the present invention is to provide a power supply cutoff method that automatically restarts power supply when the overload condition is recovered.

0004

2. Description of the Related Art FIG. 6 is a block diagram of a prior art. FIG. 6 shows a configuration example of a power supply device that uses a fuse or breaker to cut off the load side when an overload occurs.

The power converter 21 in FIG. 6 is either a DC/DC converter that inputs DC power and converts the voltage, or an AC/DC converter that converts input AC power to DC power and outputs the DC power. Voltage is supplied to a load 23 through a fuse (or breaker) 22.

[0006] When an accident or the like occurs on the load side and an overload condition occurs, the fuse (or breaker) 22 operates to cut off the load side and protect the power converter 21. However, with this method, the power supply is not automatically restarted even if the overload condition is restored, so maintenance personnel have to
It is necessary to replace or operate 2.

[0007] Furthermore, in a method of sustaining the power supply unit in an overload state in order to automatically resume power supply when the overload state is resolved, a well-known dropper type DC/DC converter as shown in FIG. In the case of a converter, when overloaded, the transistor Q7 forming the dropper portion lowers the output voltage to continue power supply, and when the overload condition is resolved, power supply is restored to normal voltage. However, this method uses transistor Q7 with a large current capacity and large heat dissipation fins.
Consideration in thermal design is required, the equipment becomes larger, and
It has the disadvantage of being expensive.

In addition to the above, there are methods of permanently locking the circuit when an overload condition occurs. This method is
For example, in the case of the DC/DC converter shown in FIG. 5, when an overload is detected, the transistor Q7 that constitutes the dropper section
A circuit (not shown) is provided to turn off and lock. However, since maintenance personnel must perform operations to restore the locked circuit, the result is no different from methods using fuses or breakers.

[0009]

[Problem to be Solved by the Invention] In the conventional power supply cutoff method, even if the output is cut off when an overload occurs, the power supply is automatically restarted when the overload condition is recovered without manual intervention. I couldn't. Furthermore, the method of automatically restarting power supply has the disadvantage that the power supply device becomes large and expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply cutoff method that automatically restarts power supply when the overload condition is recovered.

[0011]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention, and FIG. 2 is a diagram illustrating another principle of the present invention. In the figure, 1 is a power conversion unit that converts input power and outputs DC voltage and exhibits drooping characteristics when overloaded, 2 is a load, and 3 is a power converter that cuts off the power supply to the load 2 under the control of the output cutoff control means 7. An output cutoff section 4 outputs the output of the power conversion section 1 to the load by bypassing the output cutoff section 3 through an impedance 5 and a forward diode 6 when the output cutoff section 3 cuts off power supply. and voltage detection means for comparing the voltage output to the load with a preset voltage during power supply and power supply cutoff, and outputting the comparison result as a control signal; 5
is an impedance, 6 is a diode, and 7 causes the output cutoff section 3 to cut off the output when a control signal indicating that the voltage output to the load from the voltage detection means 4 is lower than a preset voltage is input. The output cutoff control means controls the output cutoff section 3 to supply power to the load 2 when a control signal indicating that the voltage output to the load is higher than a preset voltage is input. .

Further, 11 is a power conversion unit that converts input power and outputs a DC voltage, 12 is a load, 13 is an output cutoff unit that cuts off the power supply to the load 12 under the control of the output cutoff control means 17, and 17 is a power conversion unit that converts input power and outputs a DC voltage. overload current detection means that is inserted in series in the output circuit and sends out an overload detection signal when the output current to the load 12 exceeds a preset value;
14 outputs the output of the power conversion unit 11 to the load (12) through an impedance 15 and a forward diode 16, bypassing the output cutting unit 13 when the output cutting unit 13 cuts off the power supply; , outputs a control signal when an overload detection signal is received from the overload current detection means (17) during power supply, and when it is detected that the voltage output to the load is higher than a preset voltage during power supply interruption. 15 is an impedance, 16 is a diode, and 17 causes the output cutoff section 13 to cut off the output when a control signal indicating that an overload detection signal has been received from the voltage detection means 14 is inputted. When a control signal indicating that the voltage output to the load 12 is higher than a preset voltage is input, the output cutoff section 13 performs control.
This is an output cutoff control means that performs control to supply power to the load 12.

[0013]

[Operation] In FIG. 1, the output cutoff section 3 is in a conductive state when the load 2 is in a normal state, and the DC voltage output from the power conversion section 1 is supplied to the load 2.

[0014] In this state, if an accident or the like occurs in the load 2 and the load 2 becomes overloaded, the power converter 1 has a drooping characteristic, so the output voltage decreases. The voltage detection means 4 inputs the voltage output to the load during power supply and compares it with a preset voltage, but if the output voltage decreases in an overload state, the voltage will be lower than the preset voltage, so this A control signal indicating this is output to the output cutoff control means 7.

The output cutoff control means 7 detects the occurrence of overload from the control signal and controls the output cutoff section 3 to cut off the output. As a result, the power supply from the power converter 1 to the load 2 is cut off.

On the other hand, a circuit is constructed in the voltage detection means 4 to bypass the output cutoff section 3 through an impedance 5 and a diode 6, but when the load 2 is in a normal state, the output cutoff section 3 is in a conductive state. Therefore, the potentials at both ends of this parallel circuit are equal, and the diode 6 in the forward direction
is connected so that the voltage detection by the voltage detection means 4 is not affected.

When an overload occurs and the output is cut off at the output cutoff section 3, the output from the power conversion section 1 is outputted to the load 2 through the impedance 5 and the diode 6. If the output voltage to the load 2 is monitored, for example, at the intersection of the impedance 5 and the diode 6, the impedance of the load is low in an overload state, so the output cutoff section 3
The output voltage becomes even lower than the output voltage detected before the output is cut off. Therefore, the voltage detection means 4 detects that this voltage is lower than a preset value, but since this is the same as the state immediately before the output is cut off, no particular change occurs.

[0018] After the above condition continues, when the overload condition is resolved, the impedance of load 2 increases, so
The output voltage monitored by the voltage detection means 4 becomes higher than a preset value. When the voltage detection means 4 outputs a control signal notifying this to the output cutoff control means 7, the output cutoff control means 7 reduces the load (
2), the power supply to the load 2 is restarted.

As described above, in FIG. 1, overload is detected by monitoring the output voltage to the load, the power supply is cut off, and even after the power supply is cut off, the output to the load is continued through the impedance, and the output voltage is monitored. As a result, recovery from the overload condition is detected and power supply is restarted. That is, both the power supply is cut off and the power supply is restarted automatically.

Next, the operation of FIG. 2 will be explained.
Descriptions of parts that have the same effect as those will be omitted or simplified. The power converter 11 in FIG. 2 is not required to have drooping characteristics. The power supply from the power converter 11 to the load in a normal state is the same as that shown in FIG. 1 .

In this state, when an abnormality occurs in the load and the load current passing through the overload current detection means 18 exceeds a preset value, the overload current detection means 18 detects the voltage detection means 1.
An overload detection signal is sent to 4. When the voltage detection means 14 receives the overload detection signal, it outputs a control signal to the output cutoff control means 17. When the output cutoff control means 17 receives this control signal, it controls the output cutoff section (13) to cut off the output. As a result, the power supply from the power converter 1 to the load 2 is cut off.

When the output is cut off at the output cutoff section 3, the output from the power conversion section 1 is outputted to the load 2 through the impedance 5 and the diode 6. Since the output current to the load 2 can be made small by increasing the impedance 15, the output is cut off at the output cutoff section 3 and the current flowing through the load 12 and the overload current detection means 18 is reduced. , overload current detection means 1
The overload detection signal sent by No. 8 is stopped. but,
The voltage detection means 14 monitors the output voltage to the load 12 at the intersection of the impedance 5 and the diode 6, for example, and after the power supply is cut off, the control information is not displayed until it detects that the output voltage has become higher than a preset voltage. Since no output signal is sent out, the output to the load 12 remains cut off.

After this state continues, when the overload state is resolved, the output voltage increases, and the voltage detection means 14 detects that the voltage output to the load during the power supply interruption has become higher than the preset voltage. and outputs a control signal. Upon receiving this control signal, the output cutoff control means 17 controls the output cutoff section 13 to resume power supply to the load 12.

As described above, in FIG. 2, an overload is detected by monitoring the output current to the load, and the power supply is cut off. After the cutoff, output continues to the load through an impedance, and the output voltage is monitored. As a result, recovery from the overload condition is detected and power supply is restarted. That is, both the power supply is cut off and the power supply is restarted automatically.

[0025]

[Embodiment] FIG. 3 is a circuit block diagram of an embodiment of the present invention based on the principle of FIG. 1, FIG. 4 is a circuit block diagram of an embodiment of the present invention based on the principle of FIG. 2, and FIG. 5 is a configuration diagram of a power conversion section. be.

In FIGS. 3 to 5, the same objects as in FIGS. 1 and 2 are shown with the same symbols, and in FIGS. 3 and 4, the same symbols are used for the same circuit elements, and RY is a relay (
winding), ry is the contact of relay RY, IC1 and IC2 are comparators, Q1 to Q3 are transistors, D is diode, DZ1 and DZ2 are Zener diodes, R1 to R1
2 is resistance. Note that the diode D corresponds to the diode 6 and the diode 16 in FIGS. 1 and 2, and the resistor R1 corresponds to the impedance 5 and the impedance 15 in FIGS. 1 and 2.

The power converter 1 in FIG. 3 is an AC/DC converter or a DC/DC converter with drooping characteristics. FIG. 5 shows an example of a known dropper type DC/DC converter. The DC/DC converter in Figure 5 normally monitors the output voltage at the connection between resistors R3 and R4, compares it with the voltage of the Zener diode DZ3, and adjusts the output voltage between the collector and emitter of the analog transistor Q8 according to the voltage difference. The output voltage is stabilized by increasing or decreasing the current between the transistors and changing the base current of the transistor Q7, which also has analog characteristics, to change the voltage between the collector and emitter of the transistor Q7.

When an abnormality occurs in the load of the DC/DC converter shown in FIG. 5 and the current increases, the drop voltage of the resistor R17 becomes high, and when it exceeds a preset value, the transistor Q9 is turned on. As a result, the base current of the transistor Q7 changes, and the voltage between the collector and emitter changes in the direction of increasing. That is, the transistor Q7 exhibits a drooping characteristic in which the collector-emitter voltage changes in the OFF direction and the output voltage decreases when the load current increases.

In the configuration shown in FIG. 3, when the power converter 1 outputs a normal voltage, the transistors Q1 and Q2 are turned on, and the relay RY is also turned on, so that the contact ry forming the output cutoff circuit 3 is turned on. is in a conductive state. In this state, the output of the power converter 1 is supplied to the load.

At this time, the voltage output to load 2 is applied to the series circuit of resistors R1, R2, and R3, and the voltage output to load 2 is applied to the series circuit of resistors R2 and R3.
A voltage proportional to the output voltage is inputted to one terminal of the comparator IC1 from the connection point (3), and compared with the voltage of the Zener diode DZ1 inputted to the other terminal. If the voltage at point ■ is higher than the comparison voltage, the comparator IC
The output point (2) of No. 1 has a high potential, and the potential of the output point (2) of the comparator IC2 which inputs this and compares it with the same comparison voltage has a low potential, and the transistor Q1 is in the on state as described above. Note that since the polarity of diode D is opposite to the voltage output to load 2, resistor R1
The output voltage is not directly applied to the connection point (■) between and diode D.

In the above state, if an abnormality occurs in the load and an overcurrent flows, the output voltage decreases due to the drooping characteristic of the power converter 1 as described above. As a result, the potential at the point (2) decreases and becomes lower than the comparison voltage of the comparator IC1, so the potential at the point (2) becomes a low potential, and the potential at the point (2) increases to turn off the transistor Q4. This also turns off transistor Q5 and restores relay RY, so
Contact ry is turned off to cut off the output to load 2.

When the contact ry is turned off, the main current to the load 2 is cut off, and the output voltage of the power converter 1 returns to normal. The output of this power converter 1 is connected to a resistor R1 and a diode D.
The signal is output to the load by bypassing the contact ry. In the overload state, the impedance of the load 2 is low, so the voltages at points (2) and (2) decrease further than when an overload occurs. Therefore, both transistor Q1 and relay RY remain off.

When the overload condition is eliminated, the impedance of the load 2 increases, so the potentials at points ■ and ■ rise, and when they become higher than the comparison voltage of the comparator IC1, the potential at point ■ rises, and the potential at point ■ increases. decreases and transistor Q1,
Q2 is turned on and relay RY operates. As a result, contact ry of relay RY is turned on, and power supply to load 2 is restarted.

Note that the resistor R10 and Zener diode DZ2 in FIGS. 3 and 4 are connected to the comparators IC1 and I
This is a circuit for obtaining an operating power source such as C2. Next, FIG. 4 will be explained, and parts that overlap with FIG. 3 will be briefly explained.

The power converter 11 in FIG. 4 is an AC/DC
The converter is a converter or a DC/DC converter, and may be the same as the one shown in FIG. 5, but differs from FIG. 3 in that having drooping characteristics is not an essential condition.

In the configuration of FIG. 4, the normal state is similar to that of FIG. 3, where transistors Q1, Q2 and relay RY are turned on, contact ry is in a conductive state, and the output is supplied to the load.

In the above state, when an abnormality occurs in the load and an overload condition occurs, the flow through the resistor R12 constituting the overcurrent detection circuit increases, the voltage across the resistor R12 becomes large, and the transistor Q3 turns on. Therefore, the potential of one of the output lines to the load (usually the earth line) is applied to the connection point (3) between the resistors R2 and R3. This is figure 2
This corresponds to the overload detection signal in the principle of

[0038] Since almost the earth's potential is connected to point ■,
The potential at point (2) drops more clearly than in FIG. 3, and the relay RY is then restored as in FIG. 3, and the output to the load 12 is cut off. It is also the same as in FIG. 3 that when the contact ry is turned off, the output of the power converter 11 is sent to the load 12 through the resistor R1 and the diode D.

Since the current sent through this resistor R1 and diode D becomes smaller by increasing the value of resistor R1, transistor Q3 of the overcurrent detection circuit
turns off at the same time as contact ry is opened. but,
Since a load with low impedance in an overload state is connected, the potentials at points (2) and (2) are lower than in the normal state, and the relay RY remains restored.

Thereafter, monitoring of the overload condition is carried out in exactly the same manner as in FIG. 3, and when the overload condition is eliminated, relay RY operates to restart power supply. That is, in FIG. 4, overload is detected by current monitoring, and overload state is resolved by voltage monitoring. Therefore, it can be applied to the power converter 11 that does not have drooping characteristics.

Although the embodiment of the present invention has been described above with reference to FIGS. 3 to 5, FIGS. 3 to 5 merely show one embodiment of the present invention. Of course, it is not limited to. For example, the boundaries between the voltage detection section and the output cutoff control section in FIGS. 3 and 4 are not limited to those shown, and the comparison voltages of the comparator IC1 and the comparator IC2 in FIGS. 3 and 4 may be set to different values. It is also clear that it is easily possible to obtain the same effects as in FIGS. 3 to 5 by making various modifications depending on the conditions and characteristics of circuit components. In particular, the power conversion section is not limited to the circuit shown in FIG. 5, as described above.

In addition, in the comparator IC1 of FIG. 3, the same comparison voltage is used for detecting a drop in the output voltage and detecting overload recovery, but after the relay RY is operated, the contacts of the relay are used. It is easily possible to perform even more precise control by changing the comparison voltage. The present invention does not exclude such modifications.

[0043]

[Effects of the Invention] As explained above, according to the present invention,
When an overload condition occurs in the power supply device that converts input power and outputs DC voltage, the overload is automatically detected and the output to the load is cut off. It becomes possible to detect this and automatically restart the supply of power to the load. This makes it possible to quickly restart the power supply in the event of an overload caused by a temporary accident on the load side, and also makes maintenance more efficient because no human effort is required to restart the power supply.

Furthermore, since it is not necessary to increase the current capacity and heat capacity in order to automatically restart the power supply, the power supply device does not become large or expensive. As described above, the present invention greatly contributes to improving the reliability and maintenance efficiency of a power supply device.

[Brief explanation of drawings]

[Figure 1] Diagram explaining the principle of the present invention (1)

[Figure 2] Diagram explaining the principle of the present invention (2)

[Figure 3] Example circuit block diagram of the present invention (1)

[Figure 4] Example circuit block diagram of the present invention (2)

[Figure 5] Power conversion unit configuration diagram

[Figure 6] Block diagram of conventional technology

[Explanation of symbols]

1, 11 Power conversion section 2, 12 Load 3, 13 Output cutoff section 4, 14 Voltage detection means 5, 15 Impedance 6, 16 Diode 7, 17 Output cutoff control means 18 Overload current detection means

Claims (2)

[Claims] Claim 1: A power supply device that converts input power to output a DC voltage and supplies power to a load (2) from a power converter (1) that exhibits drooping characteristics during overload, comprising an output cutoff control means ( 7) The load (2) is controlled by
an output cutoff section (3) that cuts off the power supply to the output cutoff section (3), and when the output cutoff section (3) cuts off the power supply, the output of the power conversion section (1) is connected to the impedance (5) and the forward direction diode (6). A voltage that bypasses the output cutoff section (3) and outputs it to the load, and compares the voltage output to the load during power supply and power supply cutoff with a preset voltage and outputs the comparison result as a control signal. Detection means (4
), and control for causing the output cutoff section (3) to cut off the output when a control signal indicating that the voltage output to the load is lower than a preset voltage is input from the voltage detection means (4). Output cutoff control that controls the output cutoff section (3) to supply power to the load (2) when a control signal indicating that the voltage output to the load is higher than a preset voltage is input. A power supply cutoff method comprising: means (7), which automatically cuts off and restarts power supply by monitoring the output voltage to the load. 2. In a power supply device that supplies power to a load (12) from a power converter (11) that converts input power and outputs a DC voltage, the load (12) is controlled by an output cutoff control means (17). ) is inserted in series with the output circuit to cut off the power supply to the load (12).
overload current detection means (18) that sends out an overload detection signal when the output current for
), and when the output cutoff section (13) cuts off the power supply, the output of the power conversion section (11) is changed to an impedance (15
) and a forward diode (16) to bypass the output cutoff section (13) and output to the load (12), and output an overload detection signal from the overload current detection means (18) during power supply. A voltage detection means (14) that outputs a control signal when receiving the signal or when detecting that the voltage output to the load is higher than a preset voltage during power supply interruption, and detecting an overload from the voltage detection means (14). When a control signal indicating that a detection signal has been received is input, the output cutoff section (1
3) is controlled to cut off the output, and the load (12
) when a control signal indicating that the voltage output to the output cutoff section (13) is higher than a preset voltage is input.
The output cutoff control means (17) controls the power supply to the load (12), and cuts off the power supply by monitoring the output current overload to the load, and by monitoring the output voltage to the load. A power supply cutoff method that is characterized by automatically restarting power supply.