CN102761095A - Device and method for undervoltage-overvoltage protection - Google Patents

Abstract

The invention provides an undervoltage-overvoltage protection device. The protection device includes: a single tripping coil (210), which is connected in series on the power supply line, and is used to perform a tripping action when a large current is obtained; a detection circuit (220), which is used to detect that the line voltage is lower than the first predetermined When the threshold value is higher than the second predetermined threshold value, an undervoltage-overvoltage protection trigger signal is generated; a driving device (230), configured to respond to the undervoltage-overvoltage protection trigger signal, so that the tripping coil obtains a large current , so as to drive the tripping coil to perform a tripping action. Adopting this undervoltage-overvoltage protection device can realize undervoltage-overvoltage double protection through only one tripping coil.

Description

Undervoltage-overvoltage protection device and method

technical field

The invention relates to an undervoltage-overvoltage protection device and method, in particular to a device and method for dual protection of undervoltage and overvoltage using a single tripping coil. the

Background technique

Generally speaking, the voltage on the power supply line is not a constant value, and it may fluctuate correspondingly due to the change of the load. Once this voltage fluctuation (such as undervoltage or overvoltage) on the power supply line exceeds the range that the electrical equipment can withstand, it will have an adverse effect on the electrical equipment, or even cause damage to the electrical equipment. Therefore, undervoltage protection and overvoltage protection devices are usually used to ensure that the electrical equipment operates in a normal power supply state. the

Undervoltage protection generally means that when the voltage of the power supply line is lower than a predetermined threshold (for example, lower than 80% of the nominal voltage), the protection device automatically cuts off the power supply line, and when the line voltage returns to the normal range, the protection device can be activated again. Manually return to on state. Relatively speaking, overvoltage protection means that when the line voltage exceeds a predetermined value (for example, 10% higher than the nominal voltage), in order to prevent damage to the electrical equipment, the protection device also automatically cuts off the line and waits for the line voltage to return to normal. can be restored manually. the

The current undervoltage-overvoltage protection devices on the market mainly use two separate tripping coils to respectively realize undervoltage and overvoltage detection and protection actions. FIG. 1 exemplarily shows a schematic diagram of a conventional undervoltage-overvoltage protection device 100 . As shown in FIG. 1 , the power supply lines L (live line) and N (neutral line) are used to provide electric energy to the electrical equipment 150 . The protection device 100 is arranged on the electrical equipment side and includes two tripping coils 110 and 120 . These two tripping coils are used to perform tripping action when undervoltage or overvoltage is detected respectively. The tripping action of the tripping coils 110 and 120 further drives the circuit breaker 130 in a mechanical transmission manner to disconnect the electrical connection of the power supply line to the electrical device 150 . the

Specifically, in FIG. 1 , both ends of the trip coil 110 are connected to lines L and N. As shown in FIG. When the line voltage V is lower than a predetermined threshold Vmin (i.e. undervoltage), the push rod in the tripping coil 110 is in position 2, i.e. the tripped state, and then the circuit breaker 130 on the lines L and N is disconnected from the power supply connection . When the line voltage V reaches the normal range, the push rod in the tripping coil 110 changes from position 2 to position 1, so that the circuit breaker 130 is closed and the line is turned on. The trip coil 120 is connected to the power supply lines L and N via an overvoltage detection circuit 140 . When the overvoltage detection circuit 140 detects that the line voltage V is normal, the push rod in the tripping coil 120 is at position 1, so that the circuit breaker 130 is closed and the power supply line is turned on. When the overvoltage detection circuit 140 detects that the line voltage V exceeds a predetermined threshold Vmax, it outputs an overvoltage protection trigger signal, so that the push rod in the tripping coil 120 changes from position 1 to position 2, that is, enters the tripping state, And in turn cause the circuit breaker 130 on the lines L and N to disconnect the power supply connection. the

Adopting the structure shown in Figure 1 can realize double protection of undervoltage and overvoltage. However, it can be seen from Fig. 1 that this undervoltage-overvoltage protection device requires two independent tripping coils to realize undervoltage and overvoltage protection respectively. However, each tripping coil is relatively large in volume and high in cost due to its mechanical structure, especially compared with electronic components. This shortcoming obviously cannot meet the miniaturization and low-cost requirements of the current protection device. Therefore, the existing undervoltage-overvoltage protection device needs to be further improved. the

Contents of the invention

The present invention aims to propose an undervoltage-overvoltage protection device and method using a single tripping coil. Because the undervoltage-overvoltage protection device only includes one tripping coil, it is obviously superior to the existing undervoltage-overvoltage protection device with double tripping coils in terms of volume and cost. the

According to one aspect of the present invention, the undervoltage-overvoltage protection device includes: a single tripping coil, which is connected in series on the power supply line, and is used to perform a tripping action when a large current is obtained; a detection circuit, which is used to detect that the line voltage is low When the first predetermined threshold is higher than the second predetermined threshold, an undervoltage-overvoltage protection trigger signal is generated; a driving device is configured to respond to the undervoltage-overvoltage protection trigger signal so that the tripping coil obtains a large current to drive the tripping coil to perform the tripping action. Adopting this undervoltage-overvoltage protection device can realize undervoltage-overvoltage double protection through only one tripping coil. the

In one embodiment of the present invention, the driving device used to drive the tripping coil in the protection device may be a switching device connected in parallel to a load connected in series with the tripping coil, and the switching device responds to the undervoltage-overvoltage The voltage protection trigger signal is used to close, that is, the load is short-circuited so that the tripping coil can obtain a large current. Preferably, the switching device includes transistors, field effect transistors, silicon controlled rectifiers, electron tubes or relays and the like. Short-circuiting the load through the switch device can conveniently make the tripping coil obtain a large current, and the circuit is simple and easy to implement. More preferably, the detection circuit is a load connected in series with the tripping coil. the

In one embodiment of the present invention, the detection circuit in the protection device may include two parts: an overvoltage detection circuit and an undervoltage detection circuit, and an AND operation is performed on the detection results of the overvoltage detection circuit and the undervoltage detection circuit. Afterwards, the undervoltage-overvoltage protection trigger signal is obtained. Optionally, the undervoltage and overvoltage detection circuits can also be integrated and realized by a single chip. Preferably, the over-voltage and under-voltage detection circuits are implemented by comparators, or the AND logic operation is implemented by wire-AND. the

In another embodiment of the present invention, the detection circuit in the protection device may further include a verification circuit, configured to output the under-voltage-over-voltage protection trigger when it is verified that the result of the AND logic operation is greater than the third predetermined threshold Signal. Optionally, the detection circuit further includes a delay circuit for delaying the AND logic result. The use of delay and verification circuits can avoid short-term disturbances, thereby ensuring more reliable protection devices. the

In yet another embodiment of the present invention, the protection device further includes a residual current protection circuit, which is used to output a leakage protection trigger signal when a leakage phenomenon is detected, and the drive device also responds to the leakage protection trigger signal to make The tripping coil obtains a large current, so that the tripping coil performs a tripping action. In this way, the residual current protection circuit is integrated into the undervoltage and overvoltage protection circuit, and only a single tripping coil is used to realize the triple function of undervoltage, overvoltage and leakage protection. the

According to another aspect of the present invention, a method for undervoltage-overvoltage protection is also proposed. The method includes: using a single tripping coil connected in series on the power supply line and performing a tripping action when a large current is obtained; when detecting that the line voltage is lower than a first predetermined threshold or higher than a second predetermined threshold , generating an undervoltage-overvoltage protection trigger signal; in response to the undervoltage-overvoltage protection trigger signal, the tripping coil is made to obtain a large current, thereby causing the tripping coil to perform a tripping action. Therefore, adopting the method proposed by the present invention can realize double protection of undervoltage and overvoltage through a single tripping coil, thereby reducing the volume of the product and reducing the cost. the

Preferably, the method further includes generating a leakage protection trigger signal when an electric leakage phenomenon is detected; in response to the leakage protection trigger signal, the tripping coil obtains a large current, so that the tripping coil performs a tripping action. In this way, the method proposed by the present invention can realize undervoltage and overvoltage protection while integrating leakage protection, that is, the triple protection of undervoltage, overvoltage and leakage is realized through a single tripping coil. This further reduces product size and cost. the

Description of drawings

The following drawings are only intended to illustrate and explain the present invention schematically, and do not limit the scope of the present invention. in,

Fig. 1 shows the schematic diagram of existing undervoltage-overvoltage protection device;

Fig. 2 exemplarily shows a schematic structural view of an undervoltage-overvoltage protection device according to an embodiment of the present invention;

Fig. 3 shows the circuit schematic diagram of the undervoltage-overvoltage protection device according to one embodiment of the present invention;

FIG. 4 shows a schematic circuit diagram of an undervoltage-overvoltage protection device according to yet another embodiment of the present invention. the

Detailed ways

In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation manners of the present invention will now be described with reference to the accompanying drawings. the

FIG. 2 exemplarily shows a schematic diagram of an undervoltage-overvoltage protection device 200 according to an embodiment of the present invention. As shown in FIG. 2 , a protection device 200 according to an embodiment of the present invention includes a single tripping coil 210 , a detection circuit 220 and a driving device 230 . Only one tripping coil 210 is used in the protection device 200 to mechanically drive the circuit breakers 130 (such as miniature circuit breakers MCCB) on the lines L and N to switch on or off the power supply connection. Detection circuit 220 monitors whether undervoltage or overvoltage occurs on the line, and once it detects undervoltage or overvoltage, it sends a protection trigger signal to drive device 230. In response to this protection trigger signal, the driving device 230 causes the tripping coil 210 to trip due to obtaining a large current, thereby causing the circuit breaker 130 to disconnect the power supply connection. In this way, in the present invention, no matter whether the detection circuit 220 detects undervoltage or overvoltage, the only tripping coil is triggered by the driving device to realize the protection action. Using the protection device 200 shown in FIG. 2 can realize the dual function of undervoltage-overvoltage protection through only a single tripping coil 210, so that the size and cost of the protection device 200 can be reduced, and can adapt to the current miniaturization requirements. need. the

In FIG. 2 , the detection circuit 220 and the driving device 230 can be realized in various manners. For example, the driving device 230 may be a switching device connected in parallel to a load connected in series with the trip coil 210 . In a preferred simple embodiment, the detection circuit is a load connected in series with the trip coil 210 . However, those skilled in the art can understand that the load may also include other forms, for example, optionally, it may also include a resistor R0 connected in parallel with the detection circuit (as shown in FIG. 3 ). The switch device can be closed in response to the protection trigger signal of the detection circuit 220 , that is, by short-circuiting the detection circuit as a load so that the tripping coil 210 obtains a large current, thereby driving it to perform a tripping action. Optionally, the driving device 230 can also be implemented by other circuits, such as enabling the tripping coil 210 to obtain a large current through capacitor discharge, and so on. the

Likewise, the detection circuit 220 can also be realized in various manners. For example, the detection circuit can include two parts: an overvoltage detection circuit and an undervoltage detection circuit, and the detection of undervoltage and overvoltage can also be realized by a single integrated chip. Moreover, the under-voltage or over-voltage detection circuit itself can be implemented as a comparator composed of an operational amplifier, or can be implemented using a voltage detection chip available on the market, or can even be implemented using an analog comparison circuit known in the art. the

FIG. 3 shows a circuit diagram of an undervoltage-overvoltage protection device 300 according to an embodiment of the present invention. In the protection device 300, the tripping coil 210 is connected in series on the power supply line. The drive means is realized as a switching means, for example a thyristor 330 . The detection circuit 320 includes two comparators composed of op amps U1 and U2, which are used to implement undervoltage (322) and overvoltage detection (321) respectively. The under-voltage and over-voltage detection results are subjected to a line-AND operation at point B, and the obtained result is the under-voltage-over-voltage protection trigger signal, which is used to trigger the thyristor 330 . the

Specifically, in FIG. 3 , the tripping coil 210 is a high-voltage coil, which can perform a tripping action when the operating voltage is greater than 50V, for example. In FIG. 3 , the tripping coil 210 is connected in series on the line L before the rectification circuit, for example. The rectified line voltage V1 is applied to the detection circuit 320 and the thyristor 330, so that the detection circuit 320 can be regarded as a load connected in series with the trip coil, and both the detection circuit and the resistor R0 are connected in parallel with the thyristor. the

As shown in Figure 3, on one branch, the line voltage V1 is applied to the series branch formed by the resistor R10, the parallel capacitor C4 and the Zener diode D1, so as to provide stable power for each operational amplifier U1-U3 at point A. At the same time, the voltage at point A is also added to the series branch of resistors R7, R8 and R4, and stable reference voltages Vmin and Vmax are provided for operational amplifiers U1 and U2 at points A1 and A2, respectively. the

On the other branch, the line voltage V1 is added to the series branch formed by the resistor R11, the parallel R3 and the capacitor C1, and the divided line voltage V2 is obtained on the capacitor C1. The line voltage V2 is fed as the sensed line voltage to the inputs of two op amps U1 and U2 respectively. The operational amplifier U1 is used as a comparator for overvoltage detection (321). When the voltage V2 is greater than Vmax, that is, when an overvoltage occurs, U1 outputs a high level, and on the contrary outputs a low level. The operational amplifier U2 is used as a comparator for undervoltage detection (322). When the voltage V2 is less than Vmin, that is, undervoltage occurs, U2 outputs a high level. the

The output of U1 and U2 is linearly ANDed at point B. That is, when the detection result of any one of U1 and U2 is high, the voltage at point B is high. In other words, point B is high whether undervoltage or overvoltage is detected. Only the simplest line-and logic is provided here. According to actual needs, an AND logic operation can also be performed on the results output by U1 and U2 via a logic circuit such as an AND gate. The result of the AND operation can be directly used as a protection trigger signal to drive the thyristor 330 . If point B is high (undervoltage or overvoltage occurs), the thyristor 330 is turned on, and the entire detection circuit 320 as a load is short-circuited, thus the tripping coil 210 is tripped due to a large current, thereby causing an open circuit 130 is disconnected from the power supply. On the contrary, if point B is low (no undervoltage or overvoltage occurs), the thyristor 330 is cut off, the tripping coil 210 works normally, and the circuit is turned on. the

In order to avoid misoperation caused by interference, a delay circuit 325 and a verification circuit 327 are also preferably provided in the example shown in FIG. 3 . The delay circuit 325 is composed of a resistor R5 and a capacitor C2, and the delay time can be set to tens to hundreds of milliseconds as required. The delayed signal Vb is sent to the verification circuit 327 . In the verification circuit 327, U3 compares the delayed signal Vb with a reference voltage Vref (obtained by voltage dividing resistors R9 and R6). If the comparison result of U3 is that Vb is greater than Vref, it proves that undervoltage or overvoltage has indeed occurred, and U3 outputs a high level as a protection trigger signal, and this high level can also drive the thyristor 330 . In addition, in the example shown in Figure 3, it is more preferable to include a filter circuit at the output end of U3, which is composed of R13, C3 and R14, to eliminate the high-frequency variation in the protection trigger signal, so as to avoid false positives. operate. the

In the example shown in FIG. 3 , the switching device 330 is realized by a thyristor. However, those skilled in the art should understand that the switching device can also be realized by using, for example, field effect transistors, triodes, electron tubes, relays and the like. Moreover, the undervoltage and overvoltage detection circuits shown in FIG. 3 can also be replaced by other comparison circuits implemented by analog components, for example.

FIG. 4 schematically shows a circuit diagram of an undervoltage-overvoltage protection device 400 with leakage protection according to another embodiment of the present invention. As shown in FIG. 4 , the difference between the undervoltage-overvoltage protection device 400 and the protection device 300 shown in FIG. 3 is that a residual current protection circuit 450 is added. As shown in FIG. 4 , once the residual current protection circuit 450 detects the leakage phenomenon, it outputs a high level to the output terminal D of U3, and performs a wired-AND operation with the output result of U3. That is to say, no matter whether undervoltage or overvoltage is detected, once leakage is detected, the thyristor 330 will be triggered to conduct, so that the tripping coil 210 will trip due to a large current, and then cause the circuit breaker 130 to disconnect the circuit connect. the

FIG. 4 only shows an example of the residual current protection circuit 450 . The circuit 450 includes a leakage detector 451 and a control chip 455. The leakage transformer 451 sends the detected leakage current to the pin 1 - 2 of the control chip 455 . The control chip 455 judges the input leakage current. Once the control chip 455 determines that leakage has occurred, it outputs a leakage protection trigger signal at its pin 7 to the output terminal of U3 to drive the thyristor to perform corresponding operations. The structure of the residual current protection circuit here is just an example. Those skilled in the art can integrate other residual current protection circuits into the undervoltage-overvoltage protection circuit according to the present invention according to the needs of practical applications. In addition, the output of the residual current protection circuit can also be added to the point B, and the thyristor 330 can be driven after being verified by U3. the

2-4 show the structure of the undervoltage-overvoltage protection device 200, 300, 400 proposed according to the embodiment of the present invention. The above device is basically formed according to the following design ideas, that is, a single tripping coil is used, and the tripping coil is connected in series on the power supply line, and it performs a tripping action when a large current is obtained; when the line voltage is detected to be lower than the first When a predetermined threshold value or exceeds a second predetermined threshold value, an undervoltage-overvoltage protection trigger signal is generated; in response to the undervoltage-overvoltage protection trigger signal, the tripping coil is prompted to obtain a large current, thereby causing the tripping The coil performs the tripping action. The above-mentioned design idea proposed by the present invention can ensure the dual protection of undervoltage and overvoltage under the condition that only a single tripping coil is applicable, so this design idea can reduce the volume of the undervoltage-overvoltage protection device, which is suitable for current The need for miniaturization. At the same time, the above-mentioned design idea is easy to realize, and can be realized only by low-cost electronic components, thereby reducing the equipment cost while reducing the volume. the

Preferably, the design concept further includes generating a leakage protection trigger signal when the leakage phenomenon is detected; in response to the leakage protection trigger signal, the tripping coil obtains a large current, so that the tripping coil performs a tripping action . In this way, adopting the design idea proposed by the present invention can realize undervoltage and overvoltage protection while integrating leakage protection, that is, the triple protection of undervoltage, overvoltage and leakage is realized through a single tripping coil. This further reduces product size and cost. the

It should be understood that although this description is described according to various embodiments, not each embodiment only includes an independent technical solution, and this description of the description is only for clarity, and those skilled in the art should take the description as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art. the

The above descriptions are only illustrative specific implementations of the present invention, and are not intended to limit the scope of the present invention. Any equivalent changes, modifications and combinations made by those skilled in the art without departing from the concept and principle of the present invention shall fall within the protection scope of the present invention. the

Claims (15)

1. An undervoltage-overvoltage protection device, the device (200, 300, 400) comprising: A single tripping coil (210), connected in series on the power supply line, is used to perform a tripping action when a large current is obtained; A detection circuit (220), configured to generate an undervoltage-overvoltage protection trigger signal when detecting that the line voltage is lower than a first predetermined threshold or higher than a second predetermined threshold; The driving device (230) is configured to respond to the undervoltage-overvoltage protection trigger signal, so that the tripping coil obtains a large current, so as to drive the tripping coil to perform a tripping action. 2. The undervoltage-overvoltage protection device as claimed in claim 1, wherein the driving device (230) is a switching device (330) connected in parallel with the load in series with the tripping coil, and the switching device ( 330) Close in response to the undervoltage-overvoltage protection trigger signal. 3. The undervoltage-overvoltage protection device according to claim 2, wherein the switching device (330) comprises any one of transistors, field effect transistors, thyristors, electron tubes and relays. 4. The undervoltage-overvoltage protection device according to claim 2, wherein the detection circuit (220) is connected in series with the tripping coil as the load. 5. The undervoltage-overvoltage protection device according to claim 1, wherein the detection circuit (320) comprises an overvoltage detection circuit (321) and an undervoltage detection circuit (322), and is used for overvoltage detection The detection result of the circuit and the undervoltage detection circuit is an AND logic circuit for an AND operation. 6. The undervoltage-overvoltage protection device according to claim 5, wherein said overvoltage and undervoltage detection circuits comprise comparators (U1, U2). 7. The undervoltage-overvoltage protection device according to claim 6, wherein the detection circuit (320) further comprises a verification circuit (327), which is used to verify that the output signal of the AND logic circuit is greater than the third predetermined When the threshold is reached, the under-voltage-overvoltage protection trigger signal is output. 8. The undervoltage-overvoltage protection device according to claim 7, wherein the detection circuit (320) further comprises a delay circuit (325) for delaying the signal output by the AND logic circuit. 9. The undervoltage-overvoltage protection device according to claim 1, further comprising a residual current protection circuit (450), configured to output a leakage protection trigger signal when detecting a leakage phenomenon, and the driving device (230 ) also makes the tripping coil (210) obtain a large current in response to the leakage protection trigger signal, so that the tripping coil (210) performs a tripping action. 10. The undervoltage-overvoltage protection device according to claim 9, wherein, the driving device (230) is also responsive to an AND between the leakage protection trigger signal and the undervoltage-overvoltage protection trigger signal The operation results in driving the trip coil. 11. The undervoltage-overvoltage protection device according to claim 1, wherein the tripping coil (210) is a high voltage coil. 12. A method of performing undervoltage-overvoltage protection, comprising: Use a single tripping coil, which is connected in series on the power supply line and performs a tripping action when a large current is obtained; When it is detected that the line voltage is lower than the first predetermined threshold or higher than the second predetermined threshold, an undervoltage-overvoltage protection trigger signal is generated; In response to the undervoltage-overvoltage protection trigger signal, the tripping coil obtains a large current, thereby causing the tripping coil to perform a tripping action. 13. The method of claim 12, wherein the step of drawing a high current to the trip coil comprises drawing a high current to the trip coil by shorting a load in series with the trip coil. 14. The method of claim 12, further comprising: When a leakage phenomenon is detected, a leakage protection trigger signal is generated; The tripping coil (210) obtains a large current in response to the leakage protection trigger signal, so that the tripping coil (210) performs a tripping action. 15. The method according to claim 14, wherein the undervoltage-overvoltage protection trigger signal and the leakage protection trigger signal perform an AND operation, and the result of the AND operation is used to drive the tripping coil.

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