CN103490376B - For the over-and under-voltage protective device of single-phase source system - Google Patents

Abstract

The invention discloses a kind of over-and under-voltage protective device for single-phase source system.This system comprises: DC power source unit, rectification unit, sampling unit, overvoltage judge delay unit, under-voltage judgement delay unit and circuit breaker trigger element.Wherein, overvoltage judges that delay unit is the first voltage checking chip of band time delay; Under-voltage judgement delay unit comprises: the second voltage checking chip of the voltage checking chip not with time delay, RC charging circuit with a gate-controlled switch and band time delay.Realize overvoltage/undervoltage by three voltage checking chip in the embodiment of the present invention and judge time delay, the cost of over-and under-voltage protective device can be saved.

Description

Overvoltage and undervoltage protection device for single-phase power system

technical field

The invention relates to the field of power supply for power distribution systems, in particular to an overvoltage and undervoltage protection device for a single-phase power supply system.

Background technique

In the practical application of industry and household, the single-phase power system is susceptible to overvoltage or undervoltage due to the influence of external factors, and the occurrence of overvoltage or undervoltage may cause certain damage to the load and cause Certain economic losses. Therefore, it is necessary to use a circuit breaker to cut off the path of the single-phase power system to protect the circuit when overvoltage or undervoltage occurs in the single-phase power system.

Fig. 1 shows a general structural diagram of an overvoltage and undervoltage protection device for a three-phase power system. As shown in Figure 1, the system mainly includes: a DC power supply unit 10, a rectification unit 20, a sampling unit 30, an overvoltage judging unit 40, an overvoltage delay unit 50, an undervoltage judging unit 60, an undervoltage delay unit 70 and a circuit breaker Trigger unit 80.

Wherein, the direct current (DC) power supply unit 10 is used to output stable direct current power. Specifically, the voltage output of the single-phase power supply system may be stepped down and stabilized to generate a stable DC power supply. Alternatively, the DC power supply unit 10 can also step down and stabilize the voltage output of the single-phase power supply system processed by the rectification unit 20 to generate a stable DC power supply. Alternatively, the DC power supply unit 10 can also be generated by other means, such as batteries.

The rectification unit 20 is used to rectify the voltage output of the single-phase power supply system A to obtain a DC voltage output.

The sampling unit 30 is used to obtain a corresponding sampling voltage signal after step-down or step-down filter processing of the rectified DC voltage output.

The overvoltage judging unit 40 is powered by the DC power supply unit 10, and is used to compare the currently input sampling voltage signal with an overvoltage reference signal, and output an overvoltage signal when the currently input sampling voltage signal is higher than the overvoltage reference signal. pressure signal.

The overvoltage delay unit 50 is used to delay the output of the output of the overvoltage judging unit 40 for a first set time, and the time when the overvoltage judging unit 40 outputs an overvoltage signal reaches the first set time , a trigger signal is output to control the circuit breaker trigger unit 80 to trigger the coil action of the circuit breaker in the loop of the single-phase power supply system, so that the circuit breaker is disconnected.

The undervoltage judging unit 60 is powered by the DC power supply unit 10, and is used to compare the currently input sampling voltage signal with an undervoltage reference signal, and output an undervoltage when the currently input sampling voltage signal is lower than the undervoltage reference signal. pressure signal.

The undervoltage delay unit 70 is used to delay the output of the output of the undervoltage judgment unit 60 for a second set time, and the time when the undervoltage judgment unit 60 outputs the undervoltage signal reaches the second set time , a trigger signal is output to control the circuit breaker trigger unit 80 to trigger the coil action of the circuit breaker in the loop of the single-phase power supply system, so that the circuit breaker is disconnected.

At present, when implementing the above-mentioned overvoltage and undervoltage protection devices for single-phase power systems, some products mainly use operational amplifiers to realize the above-mentioned overvoltage judgment unit 40 , overvoltage delay unit 50 and circuit breaker trigger unit 80 . For example, four operational amplifiers are used, two operational amplifiers implement the overvoltage judging unit 40 and the undervoltage judging unit 60 respectively, and the two operational amplifiers respectively implement the overvoltage delay trigger and undervoltage delay trigger in the circuit breaker trigger unit 80 .

In addition, those skilled in the art are still working on finding other solutions in order to reduce the cost of the overvoltage and undervoltage protection device as much as possible when realizing the overvoltage and undervoltage protection of the single-phase power system.

Contents of the invention

In view of this, the present invention proposes an overvoltage and undervoltage protection device for a single-phase power supply system to reduce the cost of the overvoltage and undervoltage protection device for a single-phase power supply system.

The overvoltage and undervoltage protection device for a single-phase power supply system proposed by the present invention includes: a DC power supply unit, a rectification unit, a sampling unit, an overvoltage judgment delay unit, an undervoltage judgment delay unit, and a circuit breaker trigger unit, wherein :

The DC power supply unit is used to provide a stable DC power supply;

The rectification unit is used to convert the voltage output of the single-phase power system from AC to DC and then output it;

The sampling unit is used to sample the voltage output rectified by the rectification unit, and output a sampled voltage signal;

The overvoltage judgment delay unit is a first voltage detection chip with a delay, which is used to judge whether the current input sampling voltage signal is higher than its own release voltage, and if it is higher, then start the delay of the first set time , and judge whether the currently input sampling voltage signal is not lower than its own detection voltage within the first set time, and if so, output a trigger signal;

The undervoltage judgment delay unit includes: a voltage detection chip without a delay, an RC charging circuit with a first controllable switch and a second voltage detection chip with a delay; the voltage detection chip without a delay It is used to judge whether the current input sampling voltage signal is higher than its own release voltage. If it is higher, it will output a normal state signal, and maintain the normal state signal when the current input sampling voltage signal is not lower than its own detection voltage; Otherwise, the normal state signal is not output; when the RC charging circuit with a controllable switch outputs the normal state signal from the voltage detection chip without delay, the first controllable switch is in a closed state, so The RC charging circuit is not charging, and when the voltage detection chip without delay does not output the normal state signal, the first controllable switch is in an off state, and the RC charging circuit is powered by the DC power supply unit Charge, and output the corresponding detection voltage signal; the second voltage detection chip with delay is used to judge whether the current input detection voltage signal is higher than its own release voltage, if higher, start the second set time Delay, and judge whether the current input detection voltage signal is not lower than its own detection voltage within the second set time, and if so, output a trigger signal;

The circuit breaker trigger unit 80 is used to make the coil of the circuit breaker in the single-phase power system loop act when receiving the trigger signal output by the overvoltage judgment delay unit or the undervoltage judgment delay unit .

In one embodiment of the present invention, the DC power supply unit is generated by dividing and stabilizing the voltage output of a single-phase power supply system.

In one embodiment of the present invention, the DC power supply unit includes a threshold judging unit for judging the voltage output of the single-phase power supply system, and when the voltage output is lower than the set low-voltage threshold, the The DC power supply unit outputs 0 voltage or a voltage lower than a stable value; when the voltage output is higher than a set low voltage threshold, the DC power supply unit outputs a stable value voltage.

In one embodiment of the present invention, the DC power supply unit includes: a first current limiting resistor, a first voltage stabilizing tube, an energy storage capacitor and a second voltage stabilizing tube composed of at least one current limiting resistor connected in series; One end of the first current-limiting resistor is connected to the output end of the rectifier unit, and the other end is connected to the reverse end of the first voltage stabilizing tube; the forward end of the first voltage stabilizing tube is connected to one end of the energy storage capacitor respectively connected to the reverse end of the second voltage regulator tube, the other end of the energy storage capacitor and the positive end of the second voltage regulator tube are grounded; wherein, the reverse end of the second voltage regulator tube is The output terminal of the DC power supply unit; the first voltage regulator tube is not turned on when the voltage signal output by the rectifier unit is lower than the set low voltage threshold; when the voltage signal output by the rectifier unit is higher than the set voltage threshold When the low voltage threshold is set, it will be turned on.

In one embodiment of the present invention, the undervoltage judgment delay unit further includes: a first voltage divider circuit, which is used to perform voltage divider processing on the sampled voltage signal from the sampling unit and then output it to the non-delayed Voltage detection chip; the voltage detection chip without delay is used to judge whether the current input sampling voltage signal after voltage division is higher than its own release voltage, if higher, then output the normal state signal, and in the current When the input sampled voltage signal after voltage division is not lower than its own detection voltage, the normal state signal is maintained; otherwise, the normal state signal is not output.

In one embodiment of the present invention, the sampling unit includes: a second voltage divider circuit, a filter circuit and a first diode;

The second voltage dividing circuit is used to divide the voltage output of the single-phase power system rectified by the rectifying unit to obtain a sampled voltage signal;

The filtering circuit is used to filter the sampling voltage signal obtained by the voltage dividing circuit, and output the obtained filtered sampling voltage signal;

The first diode is located between the voltage divider circuit and the filter circuit, and is used to prevent the current in the filter circuit from flowing in reverse;

The first voltage dividing circuit includes: a first voltage dividing resistor composed of at least one voltage dividing resistor connected in series, and a second voltage dividing resistor composed of a second diode connected in series and at least one voltage dividing resistor; One end of the first voltage dividing resistor is connected to the output of the sampling unit, the other end is connected to one end of the second voltage dividing resistor, and the other end of the second voltage dividing resistor is grounded; the second voltage dividing resistor The non-ground end of the resistor is the output end of the first voltage divider circuit; the second diode is used to compensate the voltage drop change of the first diode caused by the temperature change.

The RC charging circuit with a first controllable switch includes: a first controllable switch, a second current limiting resistor, a third current limiting resistor, a first charging capacitor and a first discharging resistor;

One connection terminal of the first controllable switch is connected to the output terminal of the DC power supply unit through a second current limiting resistor, the other connection terminal is grounded, and the control terminal of the first controllable switch is connected to the output terminal of the DC power supply unit through a third current limiting resistor Connected to the output terminal of the voltage detection chip without delay; the first charging capacitor and the first discharging resistor are connected in parallel, and one end is connected to the output terminal of the DC power supply unit through the second current limiting resistor , and the other end is grounded.

In one embodiment of the present invention, the first controllable switch is a first triode or an NMOS transistor.

In one embodiment of the present invention, the system further includes: a signal isolation and OR unit, which is used to isolate and concentrate the outputs of the overvoltage judgment delay unit and the undervoltage judgment delay unit to One point, when any one of the outputs is a trigger signal, the trigger signal is output to the circuit breaker trigger unit.

In one embodiment of the present invention, the circuit breaker trigger unit includes: a second controllable switch, a fourth current limiting resistor, a fifth current limiting resistor, a second charging capacitor, a second discharging resistor and a thyristor;

One connection terminal of the second controllable switch is connected to the output terminal of the DC power supply unit through the fourth current limiting resistor, and the other connection terminal is connected to the second charging capacitor, one terminal of the second discharging resistor and the control terminal of the thyristor respectively. The control end of the second controllable switch is connected to the output end of the signal isolation and OR unit through the fifth current limiting resistor; the other end of the second charging capacitor and the second discharging resistor are grounded; the Thyristors are used to control the coil action of circuit breakers in single-phase power system loops when they are turned on.

In one embodiment of the present invention, the second controllable switch is a second transistor or an NMOS transistor.

In one embodiment of the present invention, the system further includes: a piezoresistor connected between the neutral line and the live line of the single-phase power supply system, for performing surge protection on the overvoltage and undervoltage protection device .

As can be seen from the above scheme, since a voltage detection chip with a delay is used in the embodiment of the present invention to realize the functions of the overvoltage judgment unit and the overvoltage delay unit, a voltage detection chip without a delay and a voltage detection chip with a delay are used. The time-delayed voltage detection chip realizes the functions of the undervoltage judging unit and the undervoltage delay unit, thereby reducing the cost of the overvoltage and undervoltage protection device of the single-phase power supply system.

Further, in the embodiment of the present invention, when the DC power supply unit performs voltage stabilization processing on the voltage signal output by the rectification unit, when the voltage signal output by the rectification unit is lower than the set low-voltage threshold, 0 voltage is output or a voltage lower than a stable value; when the voltage signal output by the rectifying unit is higher than a set low voltage threshold, a stable value voltage is output. Furthermore, when the voltage detection chip U1 without delay in the undervoltage judgment delay unit outputs the second signal at a lower voltage, since the DC power supply unit outputs 0 voltage or a voltage lower than the stable value at this time, After charging the RC charging circuit in the undervoltage judgment delay unit, it will only output a detection voltage signal of 0 or a detection voltage signal lower than the release voltage of the second voltage detection chip with delay, so that the second voltage detection chip with delay The voltage detection chip does not output a trigger signal. In this way, the following problems in the prior art can be avoided: that is, due to the mechanical characteristics of the circuit breaker itself, when the voltage of the single-phase power supply system is lower than a certain value, such as 50V or 40V, if the overvoltage and undervoltage system is always The output indicates an undervoltage trigger signal, but the release of the circuit breaker does not have enough energy to complete the mechanical action of tripping, that is, the circuit breaker cannot be disconnected, which causes a large current to pass through the circuit breaker coil for a long time, and then It will cause damage to the coil or even fire hazards.

In addition, for the case where there is a diode to prevent current reversal in the sampling unit, by setting a diode for temperature compensation in the undervoltage judgment delay unit, the judgment accuracy of the undervoltage judgment delay unit can be guaranteed to the greatest extent.

In addition, by setting the filter capacitor in the RC charging circuit of the undervoltage judgment delay unit, it can prevent the interference signal from interfering with the output signal of the voltage detection chip without delay, causing the first controllable voltage in the undervoltage judgment delay unit Misoperation of the switch.

In addition, by arranging a varistor between the neutral line N and the live line L of the single-phase power supply system, surge protection can be performed on the overvoltage and undervoltage protection device.

Description of drawings

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that those of ordinary skill in the art will be more aware of the above-mentioned and other features and advantages of the present invention. In the accompanying drawings:

FIG. 1 is a general structural diagram of an overvoltage and undervoltage protection device for a single-phase power system.

Fig. 2 is an exemplary structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in an embodiment of the present invention.

FIG. 3 is a schematic structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in another embodiment of the present invention.

FIG. 5 is a schematic structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in an example corresponding to the embodiment shown in FIG. 4 .

FIG. 6 is a schematic structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in an example corresponding to the embodiment shown in FIG. 3 .

Among them, the accompanying drawings are as follows:

10-DC power supply unit 20-rectification unit 30-sampling unit 40-overvoltage judgment unit 50-overvoltage delay unit 60-undervoltage judgment unit 70-undervoltage delay unit 80-circuit breaker trigger unit 90-overvoltage judgment delay Unit 100-undervoltage judgment delay unit 110-signal isolation, fetching or unit

detailed description

In the embodiment of the present invention, in order to reduce the cost of the overvoltage and undervoltage protection device of the single-phase power supply system, it is considered to use an inexpensive voltage detection chip with a delay to realize the overvoltage and undervoltage judgment unit and the overvoltage and undervoltage delay unit.

In order to make the purpose, technical solution and advantages of the present invention clearer, the following examples are given to further describe the present invention in detail.

Fig. 2 is an exemplary structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in an embodiment of the present invention. FIG. 3 is a schematic structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in an embodiment of the present invention. As shown in FIG. 2 , the system includes: a DC power supply unit 10 , a rectification unit 20 , a sampling unit 30 , an overvoltage judgment delay unit 90 , an undervoltage judgment delay unit 100 and a circuit breaker trigger unit 80 .

Wherein, the DC power supply unit 10 is used to provide a stable DC power supply. During specific implementation, the DC power supply unit 10 may generate a stable DC power supply after stepping down and stabilizing the voltage output of the single-phase power supply system. At this time, the DC power supply unit 10 may be directly connected to the voltage output of the single-phase power supply system, or may be connected to the voltage output of the single-phase power supply system through the rectification unit 20 . Alternatively, the DC power supply unit 10 can also be generated by other means, such as batteries.

In this embodiment, the DC power supply unit 10 is connected to the rectification unit 20 , and after stepping down and stabilizing the voltage output processed by the rectification unit 20 , a stable DC power supply is generated. In actual implementation, the DC power supply unit 10 may have various internal structures. One of them is shown in Figure 3. That is, the DC power supply unit 10 may include: a first current-limiting resistor composed of at least one current-limiting resistor R1 , R2 , R3 connected in series, an energy storage capacitor C1 , and a voltage regulator tube Z2 . Wherein, one end of the first current-limiting resistor is connected to the output end of the rectifier unit 20, and the other end is respectively connected to one end of the energy storage capacitor C1 and the reverse end of the voltage regulator tube Z2, and the energy storage capacitor The other end of C1 and the forward end of the voltage regulator transistor Z2 are grounded; wherein, the reverse end of the voltage regulator transistor Z2 is the output end of the DC power supply unit 10 .

The rectification unit 20 is used for converting the voltage output of the single-phase power system from AC to DC for output. In specific implementation, the rectification unit 20 may be a half-wave rectifier or a full-wave rectifier.

The sampling unit 30 is used for sampling the voltage output rectified by the rectifying unit 20 and outputting a sampled voltage signal. During specific implementation, the sampling unit 30 may perform step-down processing or step-down filter processing on the voltage signal output by the rectification unit 20 to obtain a sampled voltage signal.

The overvoltage judgment delay unit 90 is a first voltage detection chip U3 with a delay, which is used to judge whether the sampling voltage signal currently input by the pin 5 is higher than its own release voltage, and if it is higher, then start the first set time Delay, and determine whether the current input sampling voltage signal is not lower than its own detection voltage within the first set time, if so, the trigger signal Gate1 is output from pin 4. The trigger signal Gate1 is, for example, at a high level. Otherwise, if the currently input sampling voltage signal is lower than its own detection voltage within the first set time, the pin 4 does not output the trigger signal, that is, for example, it is at a low level.

Wherein, the release voltage of the delayed first voltage detection chip U3 is higher than its detection unit.

The undervoltage judgment delay unit 100 includes: a voltage detection chip U1 without delay, an RC charging circuit 101 with a first controllable switch, and a second voltage detection chip U2 with delay. Among them, the voltage detection chip U1 without delay is used to judge whether the sampling voltage signal currently input by pin 2 is higher than its own release voltage. and when the current input sampling voltage signal is not lower than its own detection voltage, maintain the normal state signal Out; otherwise, the pin 1 does not output the normal state signal Out, that is, it is usually low at this time. When the RC charging circuit 101 with a first controllable switch outputs the normal state signal from the voltage detection chip U1 without delay, the first controllable switch is in a closed state, and the RC charging circuit 101 does not charge , when the voltage detection chip U1 without delay does not output the normal state signal, the first controllable switch is in the off state, the RC charging circuit 101 is charged by the DC power supply unit 10, and Output the corresponding detection voltage signal. The second voltage detection chip U2 with a delay is used to judge whether the detection voltage signal currently input by the pin 5 is higher than its own release voltage. It is judged within a set time whether the current input detection voltage signal is not lower than its own detection voltage, and if so, the pin 4 outputs the trigger signal Gate2, for example, a high level. Otherwise, if the currently input sampling voltage signal is lower than its own detection voltage within the second set time, the pin 4 does not output the trigger signal Gate2 , that is, for example, a low level.

Wherein, the release voltage of the voltage detection chip U1 without delay is higher than its detection voltage, and the release voltage of the second voltage detection chip U2 with delay is higher than its detection voltage.

The circuit breaker trigger unit 80 is used to make the coil of the circuit breaker in the single-phase power system loop act when receiving the trigger signal output by the overvoltage judgment delay unit 90 or the undervoltage judgment delay unit 100 .

During specific implementation, in order to further reduce the cost of the overvoltage and undervoltage protection device in the embodiment of the present invention, the overvoltage judgment delay unit 90 and the undervoltage judgment delay unit 100 can share the components in the circuit breaker trigger unit 80, as Therefore, the overvoltage and undervoltage protection device in the embodiment of the present invention may be further shown in FIG. 3 , including a signal isolation and OR unit 110 for determining the overvoltage judgment delay unit 90 and the undervoltage judgment unit 110. The outputs of the delay unit 100 are respectively isolated and concentrated to one point, and when any one of the outputs is a trigger signal, the trigger signal is output to the circuit breaker trigger unit 80 .

During specific implementation, the signal isolation and OR unit 110 may include two diodes D7 and D8. Wherein, the anode of one diode D7 is connected with the output end of the high-voltage judgment delay unit 90, and the anode of the other diode D8 is connected with the output end of the low-voltage judgment delay unit 100; the cathodes of the two diodes D7 and D8 are connected together Afterwards, the output terminal of the signal isolation and OR unit 110 is connected to the input terminal of the circuit breaker trigger unit 80 .

In practical applications, due to the mechanical characteristics of the coil (tripping coil) of some circuit breakers, when the voltage of the single-phase power supply system is lower than a certain value, such as 50V or 40V, although the components used for undervoltage judgment, such as The undervoltage judgment delay unit 100 has been outputting a trigger signal indicating undervoltage, but the tripping coil of the circuit breaker does not have enough energy to complete the mechanical action of tripping, that is, the circuit breaker cannot be disconnected, so that the circuit breaker coil is If there is a large current passing through for a long time, it will cause damage to the coil and even fire hazards.

In order to solve this problem, in another embodiment of the present invention, when the voltage of the single-phase power supply system is lower than a certain value, such as 50V or 40V, the components used for undervoltage judgment, such as the undervoltage judgment delay unit 100, do not The output indicates the trigger signal of undervoltage. In this way, there will not be a large current passing through the circuit breaker coil for a long time, which avoids damage to the coil and fire hazards.

To this end, the DC power supply unit 10 may include a threshold judging unit for judging the voltage output of the single-phase power supply system, and when the voltage output is lower than the set low-voltage threshold, the DC power supply unit 10 will output 0 voltage or a voltage lower than a stable value; when the voltage output is higher than a set low voltage threshold, the DC power supply unit 10 is made to output a stable value voltage. Wherein, the threshold judging unit may be, for example, a Zener diode or other devices with a threshold judging function.

Fig. 4 is a schematic structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in another embodiment of the present invention. As shown in FIG. 4 , in this embodiment, on the basis of the system shown in FIG. 3 , when the DC power supply unit 10 performs voltage stabilization processing on the voltage signal output by the rectification unit 20 , when the voltage signal output by the rectification unit 20 When the voltage signal is lower than the set low-voltage threshold, the DC power supply unit 10 outputs 0 voltage or a voltage lower than a stable value; when the voltage signal output by the rectification unit 20 is higher than the set low-voltage threshold, the DC power supply The unit 10 outputs a stable value voltage. In this way, the voltage detection chip U1 without delay in the undervoltage judgment delay unit 100 outputs the second signal, and when the RC charging circuit 101 is charged by the DC power supply unit 10, since the DC power supply unit 10 outputs 0 voltage or a voltage lower than a stable value, so the RC charging circuit 101 will output a detection voltage signal of 0 or a detection voltage signal lower than the release voltage of the second voltage detection chip U2 with a delay, so that the second voltage detection chip with a delay The voltage detection chip does not output a trigger signal.

During specific implementation, before the DC power supply unit 10 in this embodiment performs voltage stabilization processing on the voltage signal output by the rectification unit 20 using a voltage stabilization circuit, a voltage regulator tube Z1 can be used as a threshold judgment unit to output the voltage of the rectification unit 20 The signal is filtered, that is, when the voltage signal output by the rectifier unit 20 is lower than the set low-voltage threshold, the regulator tube Z1 is not turned on; when the voltage signal output by the rectifier unit 20 is higher than the set low-voltage threshold, the regulator The pressure tube Z1 conducts. In this way, when the voltage of the single-phase power supply system is lower than the set low voltage threshold, such as 50V or 40V or 30V, the DC power supply unit 10 will output 0 voltage or a voltage lower than the stable value after the voltage is stabilized.

As shown in FIG. 4 , the DC power supply unit 10 may specifically include: a first current limiting resistor composed of at least one current limiting resistor R1 and R2 connected in series, a first voltage regulator transistor Z1, an energy storage capacitor C1 and a second regulator resistor Pressure tube Z2. Wherein, one end of the first current-limiting resistor is connected to the output end of the rectifier unit 20, and the other end is connected to the reverse end of the first voltage regulator transistor Z1; the forward end of the first voltage regulator transistor Z1 is respectively connected to the One end of the energy storage capacitor C1 is connected to the reverse end of the second voltage regulator transistor Z2, and the other end of the energy storage capacitor C1 and the positive end of the second voltage regulator transistor Z2 are grounded; wherein, the The reverse terminal of the second regulator transistor Z2 is the output terminal of the DC power supply unit 10 .

In specific implementation, the RC charging circuit 101 with the first controllable switch in the embodiment of the present invention may have various specific implementation forms. Only one of them is shown in FIGS. 2 to 4 . It specifically includes: a first controllable switch K1, a second current limiting resistor R12, a third current limiting resistor R11, a first charging capacitor C4, a first discharging resistor R13 and a filter capacitor C11. Wherein, one connection terminal of the first controllable switch K1 is connected to the output terminal of the DC power supply unit 10 through the second current limiting resistor R12, and the other connection terminal is grounded, and the control terminal of the first controllable switch K1 is connected to the output terminal of the DC power supply unit 10 through the second current limiting resistor R12. Three current-limiting resistors R11 are connected to the output end of the voltage detection chip U1 without delay; the first charging capacitor C4 and the first discharging resistor R13 are connected in parallel, and one end is connected to the second current-limiting resistor R12 through the second current-limiting resistor R12. The output end of the DC power supply unit 10 is connected, and the other end is grounded; one end of the filter capacitor C11 is connected to the output end of the voltage detection chip U1 without delay through the third current limiting resistor R11, and the other end is grounded. Wherein, the filter capacitor C11 is used to prevent the interference signal from interfering with the output signal of the voltage detection chip U1 without delay, causing malfunction of the first controllable switch K1. In practical applications, if the interference signal can be ignored, the filter capacitor C11 can be omitted.

During specific implementation, the first controllable switch K1 may be a triode tube, or an NMOS tube, etc.

Preferably, in the embodiment of the present invention, the release voltage of the voltage detection chip U1 without delay is lower than the release voltage of the first voltage detection chip U3 with delay, for example, the release voltage of the voltage detection chip U1 without delay The voltage can be 2V, and the release voltage of the first voltage detection chip U3 with delay can be 4V, etc. In addition, the first voltage detection chip U3 with delay and the second voltage detection chip U2 with delay can be the same type of voltage detection chip, and both can have the same release voltage, which facilitates the procurement of components.

Two examples are given below to describe in detail a specific implementation of the overvoltage and undervoltage protection device based on the single-phase power supply system shown in FIG. 4 and FIG. 3 respectively.

example one

FIG. 5 is a schematic structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in an example corresponding to the embodiment shown in FIG. 4 . As shown in FIG. 5 , the coil of the circuit breaker L1 is connected in series in the loop of the live line L and the neutral line N of the phase-to-phase power system.

In this example, the rectification unit 20 adopts full-wave rectification, that is, four diodes D1, D2, D3, and D4 are used to perform full-wave rectification on the voltage output of the single-phase power system.

The internal structure of the DC power supply unit 10 in this example is consistent with the internal structure in FIG. 3 , and will not be repeated here.

The sampling unit 30 in this example includes: a voltage divider circuit, a filter circuit and a first diode D5.

Wherein, the voltage dividing circuit is used for performing voltage dividing processing on the voltage output of the single-phase power system rectified by the rectifying unit 20 to obtain a sampled voltage signal. Specifically, the voltage dividing circuit includes: a first voltage dividing resistor composed of at least one voltage dividing resistor R4, R5, R6 connected in series, and a second voltage dividing resistor composed of at least one voltage dividing resistor R18, R7 connected in series. Wherein, one end of the first voltage dividing resistor is connected to the output end of the rectifying unit 20 , the other end is connected to the second voltage dividing resistor, and the other end of the second voltage dividing resistor is grounded. The non-ground terminal of the second voltage dividing resistor is the output terminal of the voltage dividing circuit. During specific implementation, the first voltage dividing resistor can be implemented with one resistor or other numbers of resistors. Likewise, the second voltage dividing resistor can also be realized with one resistor or other numbers of resistors.

The filtering circuit is used to filter the sampling voltage signal obtained by the voltage dividing circuit, and output the obtained filtered sampling voltage signal. In a specific implementation, the filter circuit may include a filter capacitor C2 and a discharge resistor R8, and the filter capacitor C2 and the discharge resistor R8 are connected in parallel.

The first diode D5 is located between the voltage divider circuit and the filter circuit, and is used to prevent the sampling voltage signal in the filter circuit from being reversed. The anode of the first diode D5 is connected to the output end of the voltage divider circuit, the cathode is connected to one end of the filter circuit, and the other end of the filter circuit is grounded. Wherein, the non-ground terminal of the filter circuit is the output terminal of the sampling unit 30 .

In this example, a voltage regulator tube Z3 may be further included in the voltage divider circuit, and the voltage regulator tube Z3 is connected in parallel with the second voltage divider resistor for surge protection of the overvoltage and undervoltage protection device. Of course, if the filter capacitor C2 is set to be large enough in actual implementation, the regulator tube Z3 for surge protection can be omitted.

The internal structure of the overvoltage judging delay unit 90 in this example is consistent with the internal structures in FIG. 2 and FIG. 3 , and will not be repeated here.

The under-voltage judgment delay unit 100 in this example further includes a voltage divider circuit before the voltage detection chip U1 without delay. In practical applications, whether the voltage divider circuit is needed can be determined according to the specific selection of the voltage detection chip U1 without delay and the voltage detection chip U2 with delay. For example, if the combination of the voltage detection chip U1 without delay and the voltage detection chip U2 with delay is selected, the release voltage value and detection voltage value of the voltage detection chip U1 without delay are within the current sampling voltage signal If the requirements can be met, the voltage divider circuit is not needed. If the requirements cannot be met, the voltage of the current sampling voltage signal can be adjusted by using the voltage divider circuit, so that the release voltage value and detection voltage value of the voltage detection chip U1 without delay can meet the requirements of the adjusted voltage signal. Require.

In this example, the voltage dividing circuit includes: a first voltage dividing resistor composed of at least one voltage dividing resistor R19, R9 connected in series, and a second diode D6 connected in series and at least one voltage dividing resistor R10. Second voltage divider resistor. Wherein, one end of the first voltage dividing resistor is connected to the output of the sampling unit 30, the other end is connected to one end of the second voltage dividing resistor, and the other end of the second voltage dividing resistor is grounded; The non-ground terminal of the two voltage dividing resistors is the output terminal of the voltage dividing circuit. Wherein, the second diode D6 is used for temperature compensation of the voltage drop change of the first diode D5 caused by the temperature change. In practical applications, if the voltage drop change of the first diode D5 caused by the temperature change can be ignored, the second diode can be omitted.

In addition, the voltage dividing circuit may include: a filter capacitor C3 for filtering the divided sampled voltage signal and outputting the filtered sampled voltage signal to the voltage detection chip U1 without delay.

In this example, the first controllable switch K1 in the undervoltage judgment delay unit 100 is implemented by a transistor Q1. Other structures and implementations in the undervoltage judgment delay unit 100 are consistent with the descriptions in FIG. 2 and FIG. 3 , and will not be repeated here.

The internal structure of the signal isolation and OR unit 110 in this example is consistent with the description in FIG. 3 , and will not be repeated here.

The circuit breaker trigger unit 80 in this example is mainly realized by a thyristor T1. The internal structure of the breaker trigger unit 80 specifically includes: a second controllable switch, a fourth current limiting resistor R15 , a fifth current limiting resistor R14 , a second charging capacitor C5 , a second discharging resistor R16 and a thyristor T1 . Wherein, one connection end of the second controllable switch is connected to the output end of the DC power supply unit 10 through the fourth current limiting resistor R15, and the other connection end is respectively connected to the second charging capacitor C5, one end of the second discharging resistor R16 and The control terminal of the thyristor T1 is connected, and the control terminal of the second controllable switch is connected with the output terminal of the signal isolation and OR unit 110 through the fifth current limiting resistor R14; the second charging capacitor C5 and the second discharging The other end of the resistor R16 is grounded; the thyristor T1 is used to control the action of the coil L1Coil of the circuit breaker in the loop of the single-phase power supply system when it is turned on. In the example shown in Fig. 5, preferably, the trip coil L1Coil of the circuit breaker is connected in series with the thyristor T1 to the outputs L and N of the single-phase power supply. In this way, when T1 is turned on, the tripping coil L1Coil will obtain a large current in a short time, thereby performing a tripping action, and then mechanically prompting the circuit breaker to operate. Figure 5 only shows one connection mode of the tripping coil and trigger unit. However, the protection device proposed by the present invention can be adapted to many different triggering designs and is not limited to the situation shown in FIG. 5 , which is obvious to those skilled in the art.

In addition, the overvoltage and undervoltage protection device in this example further includes a piezoresistor R17 connected between the neutral line N and the live line L of the single-phase power supply system, which is used to control the overvoltage and undervoltage protection device Get surge protection.

In the embodiment of the present invention, multiple sub-resistors are used to form a current-limiting resistor or a voltage-dividing resistor in circuits such as the DC voltage unit and the sampling unit, which can make full use of the limited narrow space, reduce system power consumption, and achieve better heat dissipation area.

The working process of the overvoltage and undervoltage protection device in this example is as follows:

When the input single-phase AC voltage is greater than 0V and lower than a certain value, that is, lower than the predetermined low voltage value (such as 30V), it is in an undervoltage state at this time, the voltage regulator Z1 is not conducting, and the voltage across the voltage regulator Z2 is 0V, when the input single-phase AC voltage continues to increase, but is still less than a certain value (such as 40V), the Zener tube Z1 starts to conduct, and the voltage across the Zener tube Z2 is less than a certain value, that is, the VCC voltage is 0 or less than A certain value, the voltage of the voltage input terminal VDD of the voltage detection chip U1 without delay is lower than the release voltage of the voltage detection chip U1, the voltage detection chip U1 does not output high level, and the transistor Q1 is in the cut-off state. Since the VCC voltage is 0 Or less than a certain value, so the voltage of the voltage input terminal VDD of the voltage detection chip U2 with delay is also 0 or less than its release voltage, at this time the voltage detection chip U2 does not output high level, the thyristor T1 is not turned on, there is no A large current flows through the coil.

When the input AC voltage gradually increases, it is still in an undervoltage state at this time, the regulator Z1 is turned on, the voltage of the DC power supply unit 10 is large enough, and the voltage of the voltage input terminal VDD of the voltage detection chip U1 is lower than that of the voltage detection chip U1 The release voltage of the voltage detection chip U1 does not output high level, the transistor Q1 is in the cut-off state, the voltage at both ends of the Zener tube Z2 begins to increase, and the VCC voltage begins to increase. At this time, the voltage of the voltage input terminal VDD of the voltage detection chip U2 begins to increase. Increase, the voltage of the voltage input terminal VDD of the voltage detection chip U2 is greater than the release voltage of the voltage detection chip U2, and is not lower than the detection voltage of the voltage detection chip U2 for a period of time, at this time, the voltage detection chip U2 outputs a high level, At this time, the thyristor T1 is turned on, a large current flows through the coil, and the release mechanism of the circuit breaker operates.

When the input AC voltage continues to increase, it is in a normal state at this time, the voltage of the voltage input terminal VDD of the voltage detection chip U1 is greater than the release voltage of the voltage detection chip U1, the voltage detection chip U1 outputs a high level, and the transistor Q1 is in a conducting state. At this time, the voltage of the voltage input terminal VDD of the voltage detection chip U2 is 0, and the voltage detection chip U2 does not output a high level. At this time, the voltage of the voltage input terminal VDD of the voltage detection chip U3 is lower than the detection voltage of the voltage detection chip U3, and the voltage detection chip U3 does not output a high level at this time, and the thyristor T1 is not turned on at this time, and no large current flows through the coil.

When the input AC voltage continues to increase, it is in an overvoltage state at this time, the voltage of the voltage input terminal VDD of the voltage detection chip U3 is greater than the release voltage of the voltage detection chip U3, and is not lower than the detection voltage of the voltage detection chip U3 for a period of time At this time, the voltage detection chip U3 outputs a high level, and the thyristor T1 is turned on at this time, a large current passes through the coil, and the release mechanism of the circuit breaker operates.

Example two

FIG. 6 is a schematic structural diagram of an overvoltage and undervoltage protection device for a single-phase power supply system in an example corresponding to the embodiment shown in FIG. 3 . As shown in Figure 6, in this example, the regulator tube Z1 in Figure 5 is replaced by a current limiting resistor R3, while other structures are the same.

The working process of the overvoltage and undervoltage protection device in this example is as follows:

When the input single-phase AC voltage is greater than 0V and lower than the undervoltage reference value, it is in an undervoltage state at this time, and the voltage at both ends of the Zener tube Z2 gradually increases to a stable value, and the voltage detection chip U1 without delay The voltage of the voltage input terminal VDD is lower than the release voltage of the voltage detection chip U1, the voltage detection chip U1 does not output high level, the triode Q1 is in the cut-off state, and the voltage of the voltage input terminal VDD of the voltage detection chip U2 with delay is greater than its The voltage is released, and within a period of time it is not lower than the detection voltage of the voltage detection chip U2. At this time, the voltage detection chip U2 outputs a high level, the thyristor T1 is turned on, a large current passes through the coil, and the release mechanism of the circuit breaker operates.

When the input AC voltage continues to increase, it is in a normal state at this time, the voltage of the voltage input terminal VDD of the voltage detection chip U1 is greater than the release voltage of the voltage detection chip U1, the voltage detection chip U1 outputs a high level, and the transistor Q1 is in a conducting state. At this time, the voltage of the voltage input terminal VDD of the voltage detection chip U2 is 0, and the voltage detection chip U2 does not output a high level. At this time, the voltage of the voltage input terminal VDD of the voltage detection chip U3 is lower than the detection voltage of the voltage detection chip U3, and the voltage detection chip U3 does not output a high level at this time, and the thyristor T1 is not turned on at this time, and no large current flows through the coil.

When the input AC voltage continues to increase, it is in an overvoltage state at this time, the voltage of the voltage input terminal VDD of the voltage detection chip U3 is greater than the release voltage of the voltage detection chip U3, and is not lower than the detection voltage of the voltage detection chip U3 for a period of time At this time, the voltage detection chip U3 outputs a high level, and the thyristor T1 is turned on at this time, a large current passes through the coil, and the release mechanism of the circuit breaker operates.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (12)

1. An overvoltage and undervoltage protection device for a single-phase power supply system, comprising: a DC power supply unit (10), a rectification unit (20), a sampling unit (30), an overvoltage judgment delay unit (90), an undervoltage Voltage judgment delay unit (100) and circuit breaker trigger unit (80), wherein: The DC power supply unit (10) is used to provide a stable DC power supply; The rectification unit (20) is used to convert the voltage output of the single-phase power system from AC to DC for output; The sampling unit (30) is used to sample the voltage output rectified by the rectification unit (20), and output a sampled voltage signal; The overvoltage judgment delay unit (90) is a first voltage detection chip (U3) with time delay, which is used to judge whether the current input sampling voltage signal is higher than its own release voltage, and if higher, start the first Set the time delay, and judge whether the current input sampling voltage signal is not lower than its own detection voltage within the first set time, if so, output a trigger signal, wherein the release voltage is higher than the detection voltage; The undervoltage judgment delay unit (100) includes: a voltage detection chip (U1) without time delay, an RC charging circuit (101) with a first controllable switch and a second voltage detection chip (U2) with time delay ), The voltage detection chip (U1) without delay is used to judge whether the current input sampling voltage signal is higher than its own release voltage, if higher, then output a normal state signal, and when the current input sampling voltage signal is not When it is lower than its own detection voltage, the normal state signal is maintained; otherwise, the normal state signal is not output; When the RC charging circuit (101) with a controllable switch outputs the normal state signal from the voltage detection chip (U1) without delay, the first controllable switch is in a closed state, and the RC charging circuit The circuit (101) is not charging, and when the voltage detection chip (U1) without delay does not output the normal state signal, the first controllable switch is in an off state, and the RC charging circuit (101) Charged by the DC power supply unit (10), and output a corresponding detection voltage signal; The second voltage detection chip (U2) with time delay is used to judge whether the current input detection voltage signal is higher than its own release voltage, if higher, start the delay time of the second set time, and 2. Judging whether the current input detection voltage signal is not lower than its own detection voltage within the set time, if so, output a trigger signal; The circuit breaker trigger unit (80) is used to make the single-phase power system The coil of the circuit breaker in the circuit operates. 2. The overvoltage and undervoltage protection device for a single-phase power supply system according to claim 1, wherein the DC power supply unit (10) divides and stabilizes the voltage output of the single-phase power supply system generated after. 3. The overvoltage and undervoltage protection device for a single-phase power supply system according to claim 2, characterized in that, the DC power supply unit (10) includes a threshold judging unit for controlling the single-phase power supply system When the voltage output is lower than a set low voltage threshold, the DC power supply unit (10) is made to output 0 voltage or a voltage less than a stable value; when the voltage output is higher than the set When the low-voltage threshold is low, the DC power supply unit (10) is made to output a stable value voltage. 4. The overvoltage and undervoltage protection device for single-phase power supply system according to claim 3, characterized in that, the DC power supply unit (10) comprises: at least one current limiting resistor (R1, R2) connected in series ) composed of the first current limiting resistor, the first voltage regulator tube (Z1), the energy storage capacitor (C1) and the second voltage regulator tube (Z2); one end of the first current limiting resistor and the rectifier unit (20) The output end is connected, and the other end is connected with the reverse end of the first voltage regulator tube (Z1); the forward end of the first voltage regulator tube (Z1) is respectively connected with one end of the energy storage capacitor (C1) and the The opposite end of the second voltage regulator tube (Z2) is connected, the other end of the energy storage capacitor (C1) and the positive end of the second voltage regulator tube (Z2) are grounded; wherein, the second voltage regulator tube (Z2) is grounded; The reverse end of the tube (Z2) is the output end of the DC power supply unit (10); the voltage signal output by the first regulator tube (Z1) in the rectification unit (20) is lower than the set low-voltage threshold When the voltage signal output by the rectification unit (20) is higher than the set low voltage threshold, it is switched on. 5. The overvoltage and undervoltage protection device for a single-phase power supply system according to any one of claims 1 to 4, wherein the undervoltage judgment delay unit (100) further comprises: a first branch A voltage circuit, which is used to divide the sampling voltage signal from the sampling unit (30) and then output it to the voltage detection chip (U1) without delay; the voltage detection chip (U1) without delay It is used to judge whether the current input sampled voltage signal after divided voltage is higher than its own release voltage. If it is higher than its own release voltage, the normal state signal will be output, and the currently input sampled voltage signal after divided voltage is not lower than its own When the voltage is detected, the normal state signal is maintained; otherwise, the normal state signal is not output. 6. The overvoltage and undervoltage protection device for single-phase power supply system according to claim 5, characterized in that, the sampling unit (30) comprises: a second voltage divider circuit, a filter circuit and a first diode (D5); The second voltage dividing circuit is used to perform voltage dividing processing on the voltage output of the single-phase power system rectified by the rectifying unit (20), to obtain a sampled voltage signal; The filtering circuit is used to filter the sampling voltage signal obtained by the voltage dividing circuit, and output the obtained filtered sampling voltage signal; The first diode (D5) is located between the voltage divider circuit and the filter circuit, and is used to prevent the current in the filter circuit from flowing in reverse; The first voltage dividing circuit includes: a first voltage dividing resistor formed by at least one voltage dividing resistor (R19, R9) connected in series, and a second diode (D6) connected in series and at least one voltage dividing resistor (R10) constitutes a second voltage dividing resistor; one end of the first voltage dividing resistor is connected to the output of the sampling unit (30), and the other end is connected to one end of the second voltage dividing resistor, and the second voltage dividing resistor is connected to the output of the sampling unit (30). The other end of the voltage dividing resistor is grounded; the non-ground end of the second voltage dividing resistor is the output end of the first voltage dividing circuit; the second diode (D6) is used for the first diode The tube (D5) is compensated for pressure drop changes caused by temperature changes. 7. The overvoltage and undervoltage protection device for a single-phase power supply system according to any one of claims 1 to 4, wherein the RC charging circuit (101) with a first controllable switch comprises: The first controllable switch (K1), the second current limiting resistor (R12), the third current limiting resistor (R11), the first charging capacitor (C4) and the first discharging resistor (R13); One connection end of the first controllable switch (K1) is connected to the output end of the DC power supply unit (10) through a second current limiting resistor (R12), the other connection end is grounded, and the first controllable switch The control terminal of (K1) is connected with the output terminal of the voltage detection chip (U1) without delay through the third current limiting resistor (R11); the first charging capacitor (C4) and the first discharging resistor (R13 ) are connected in parallel, and one end is connected to the output end of the DC power supply unit (10) through the second current limiting resistor (R12), and the other end is grounded. 8. The overvoltage and undervoltage protection device for a single-phase power supply system according to claim 7, characterized in that, the first controllable switch (K1) is a first transistor (Q1) or an NMOS transistor. 9. The overvoltage and undervoltage protection device for a single-phase power supply system according to any one of claims 1 to 4, characterized in that, the device further comprises: a signal isolation, OR unit (110), used The outputs of the overvoltage judgment delay unit (90) and the undervoltage judgment delay unit (100) are respectively isolated and concentrated at one point, and when any one of the outputs is a trigger signal, the trigger signal is output to the circuit breaker trigger unit (80). 10. The overvoltage and undervoltage protection device for single-phase power supply system according to claim 9, characterized in that, the circuit breaker trigger unit (80) comprises: a second controllable switch, a fourth current limiting resistor ( R15), the fifth current limiting resistor (R14), the second charging capacitor (C5), the second discharging resistor (R16) and the thyristor (T1); One connection end of the second controllable switch is connected to the output end of the DC power supply unit (10) through the fourth current limiting resistor (R15), and the other connection end is respectively connected to the second charging capacitor (C5), the second One end of the discharge resistor (R16) is connected to the control end of the thyristor (T1), and the control end of the second controllable switch is isolated from the output of the signal and OR unit (110) through the fifth current limiting resistor (R14). The other end of the second charging capacitor (C5) and the second discharging resistor (R16) are grounded; the thyristor (T1) is used to control the coil of the circuit breaker in the single-phase power system loop when it is turned on ( L1Coil) action. 11. The overvoltage and undervoltage protection device for a single-phase power supply system according to claim 10, characterized in that, the second controllable switch (K2) is a second transistor (Q2) or an NMOS transistor. 12. The overvoltage and undervoltage protection device for a single-phase power supply system according to any one of claims 1 to 4, characterized in that the device further comprises: a neutral line connected to the single-phase power supply system The varistor (R17) between the live wire and the live wire is used for surge protection of the overvoltage and undervoltage protection device.