CN112255450A - Self-checking circuit and method and residual current detection device - Google Patents

Abstract

The invention discloses a self-checking circuit, a self-checking method and a residual current detection device. Wherein, this self-checking circuit includes: a first terminal for inputting a detection voltage; a second terminal connected to a reference ground; a third terminal for inputting a first control signal to make the self-checking circuit enter a first conduction state to detect whether the detection precision of the residual current detection device is abnormal; a fourth terminal, which inputs the second control signal on the basis of maintaining the first control signal input from the third terminal, so that the self-checking circuit enters a second conduction state to detect whether the detection ratio of the residual current detection device is abnormal or not; wherein, the detection proportion is a proportional relation between the residual current detection value and the actual residual current value of the detected device. According to the invention, the self-checking is carried out before the residual current detection device is formally used, so that the accuracy of the detection result is ensured, and the influence on the normal operation of the current transformer caused by the fact that the residual current detection device cannot accurately and precisely detect the residual current is avoided.

Description

Self-checking circuit and method and residual current detection device

Technical Field

The invention relates to the technical field of electronic circuits, in particular to a self-checking circuit, a self-checking method and a residual current detection device.

Background

The photovoltaic power generation intelligent converter which meets the electrical safety design requirement must be provided with a residual current detection device. No matter be board-mounted and need the residual current detection device of outside threading type, still carry residual current detection device from taking wire type board, its self does not have self-checking circuit, needs to increase external circuit and realizes the self-checking. If no self-checking circuit is arranged in an external supporting circuit, whether the conduction condition, the detection precision and the detection proportion of the residual current detection device are normal or not is not determined when the intelligent converter is electrified and works. When the detection precision or the detection proportion of the residual current detection device is abnormal, the detection result cannot reflect the actual residual current condition of the converter, so that when the intelligent converter is electrified and operated, the residual current is actually small and is repeatedly protected by mistake, or the residual current exceeds the standard and the converter does not report a fault. In any case, the normal operation of the converter can be influenced, and even the personal safety can be endangered in serious conditions, so that safety accidents are easy to happen.

Aiming at the problem that the detection result cannot reflect the actual residual current condition of the converter due to the abnormal detection precision or detection proportion of the residual current detection device in the prior art, an effective solution is not provided at present.

Disclosure of Invention

The embodiment of the invention provides a self-checking circuit, a self-checking method and a residual current detection device, and aims to solve the problem that in the prior art, the detection result cannot reflect the actual residual current condition of a current transformer due to the fact that the detection precision or the detection proportion of the residual current detection device is abnormal.

In order to solve the above technical problem, the present invention provides a self-checking circuit, which is applied to a residual current detection device, the self-checking circuit comprising:

a first terminal for inputting a detection voltage;

a second terminal connected to a reference ground;

a third terminal for inputting a first control signal to make the self-checking circuit enter a first conduction state to detect whether the detection precision of the residual current detection device is abnormal;

a fourth terminal, which inputs a second control signal on the basis of maintaining the first control signal input from the third terminal, so that the self-checking circuit enters a second conduction state to detect whether the detection ratio of the residual current detection device is abnormal or not; wherein the detection proportion is a proportional relation between the residual current detection value and an actual residual current value of the detected device.

Further, the self-test circuit includes:

the first detection branch circuit is arranged between the first terminal and the second terminal and used for conducting under the control of the first control signal so as to enable the self-detection circuit to enter a first conducting state;

and the second detection branch is connected with the first detection branch in parallel and is used for being switched on under the control of the second control signal after the first detection branch is switched on, so that the self-detection circuit enters a second conduction state.

Further, at least one resistor is included in the first detection branch and the second detection branch.

Further, at least one of the resistors in the first or second detection branch is a variable resistor.

Further, the self-test circuit further comprises:

the first switch is arranged between a connecting point of the first detection branch and the second terminal and is used for conducting under the control of the first control signal so as to control the conduction of the first detection branch;

and the second switch is arranged on the second detection branch and is used for conducting under the control of the second control signal on the basis of conducting the first switch, so as to control the conduction of the second detection branch.

Further, the self-test circuit further comprises:

a third switch disposed between a connection point of the first detection branch and the second detection branch and the first terminal;

and a fifth terminal for inputting a third control signal to turn on the third switch.

Further, the self-test circuit further comprises:

first binding post and second binding post, first binding post with second binding post sets up first detection branch road with the second detects the junction point on branch road with between the first terminal, first binding post is used for connecting the first end of residual current detection device's detection wire, second binding post is used for connecting the second end of detection wire.

Further, the self-test circuit further comprises: the switching module is used for switching a first control signal input by a third terminal to obtain a first switching signal, and the first switching signal is used for controlling the self-checking circuit to enter a first conduction state;

the conversion module is further configured to convert a second control signal input by the fourth terminal to obtain a second conversion signal, where the second conversion signal is used to control the self-checking circuit to enter a second conduction state.

The invention also provides a residual current detection device which comprises the self-detection circuit.

The invention also provides a current transformer which comprises the residual current detection device.

The invention also provides a self-checking method, which is applied to the self-checking circuit and comprises the following steps:

triggering a first control signal input to enable the self-checking circuit to enter a first conduction state so as to judge whether the detection precision of the residual current detection device is abnormal or not;

if the detection precision of the residual current detection device is normal, triggering a second control signal input on the basis of maintaining the first control signal input so as to enable the self-detection circuit to enter a second conduction state to judge whether the detection proportion of the residual current detection device is abnormal or not.

Further, the judging whether the detection accuracy of the residual current detecting means is abnormal includes:

judging whether the residual current detection value is consistent with the calculated value;

if yes, judging that the detection precision of the residual current detection device is normal;

and if not, judging that the detection precision of the residual current detection device is abnormal.

Further, determining whether the detection ratio of the residual current detection device is abnormal includes:

respectively calculating a first ratio between a residual current detection value in a first conduction state and a residual current detection value in a second conduction state, and a second ratio between a residual current calculation value in the first conduction state and a residual current calculation value in the second conduction state;

judging whether the first ratio is consistent with the second ratio;

if yes, judging that the detection proportion of the residual current detection device is normal;

if not, judging that the detection proportion of the residual current detection device is abnormal.

Further, before determining whether the detection accuracy of the residual current detection device is abnormal, the method further includes:

judging whether residual current is detected;

if not, judging that the residual current detection device is abnormal in conduction;

if yes, triggering and judging whether the detection precision of the residual current detection device is abnormal or not.

Further, triggering a first control signal input to cause the self-test circuit to enter a first conducting state includes:

and triggering a first control signal input to enable the first switch to be conducted, and further controlling the first detection branch circuit to be conducted, so that the self-detection circuit enters a first conduction state.

Further, triggering the second control signal input on the basis of maintaining the first control signal input to cause the self-test circuit to enter the second conducting state comprises:

and triggering a second control signal input to enable the second switch to be conducted, and further controlling the conduction of the second detection branch circuit to enable the self-detection circuit to enter a second conduction state.

Further, before triggering the first control signal input, the method further comprises:

triggering a third control signal input to turn on the third switch; the third switch is arranged between a connecting point of the first detection branch and the second detection branch and the first terminal of the self-checking circuit.

The present invention also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the above-described self-test method.

By applying the technical scheme of the invention, the self-checking circuit inputs the detection voltage through the first terminal; a reference ground is connected through the second terminal, and a current loop is formed with the first terminal; inputting a first control signal through a third terminal to enable the self-checking circuit to enter a first conduction state so as to detect whether residual current is generated and determine whether the value of the residual current is abnormal; on the basis that the third terminal keeps inputting the first control signal through the fourth terminal, the second control signal is input, so that the self-checking circuit enters a second conduction state, whether the detection proportion of the residual current detection device is abnormal or not is detected, the self-checking can be carried out before the residual current detection device is formally used, the accuracy of a detection result is ensured, and the influence on the normal operation of the converter due to the fact that the residual current detection device cannot accurately and precisely detect the residual current is avoided.

Drawings

FIG. 1 is a block diagram of a self-test circuit according to an embodiment of the invention;

FIG. 2 is a block diagram of a self-test circuit according to an embodiment of the invention;

FIG. 3 is a block diagram of a self-test circuit according to another embodiment of the present invention;

FIG. 4 is a flow chart of a detection method according to an embodiment of the invention;

FIG. 5 is a flow chart of a detection method according to another embodiment of the present invention;

FIG. 6 is a flow chart of a detection method according to another embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.

It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

It should be understood that although the terms first, second, etc. may be used to describe the detection legs in embodiments of the present invention, these detection legs should not be limited to these terms. These terms are only used to distinguish between different detection branches. For example, a first detection branch may also be referred to as a second detection branch, and similarly, a second detection branch may also be referred to as a first detection branch, without departing from the scope of embodiments of the present invention.

The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.

It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in the article or device in which the element is included.

Alternative embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Example 1

The present embodiment provides a self-checking circuit, which is applied in a residual current detection device, and fig. 1 is a structural diagram of the self-checking circuit according to an embodiment of the present invention, as shown in fig. 1, the self-checking circuit includes: a first terminal 1 for inputting a detection voltage, wherein the detection voltage is provided by an external power supply or is output by a residual current detection device. And a second terminal 2 connected to a reference ground to form a current loop.

The self-checking circuit further includes a third terminal 3 for inputting a first control signal to make the self-checking circuit enter a first conduction state to detect whether the detection precision of the residual current detection device is abnormal.

If the detection precision of the residual current detection device is normal, it is necessary to determine whether the detection ratio is accurate, so that the self-checking circuit of this embodiment further includes a fourth terminal 4, and on the basis of maintaining the first control signal input from the third terminal 3, the second control signal is input from the fourth terminal 4, so that the self-checking circuit enters the second conduction state to detect whether the detection ratio of the residual current detection device is abnormal, wherein the total resistance value of the self-checking circuit is different between the first conduction state and the second conduction state. If the detection precision and/or the detection proportion are abnormal, the detection result of the residual current detection device is abnormal, and the situation of the residual current actually generated in the detected device cannot be reflected.

When the residual current detection device detects the current of the current transformer, the current transformer is positioned on the primary side, the detection residual current detection device is positioned on the secondary side, if the residual current is generated in the current transformer on the primary side, an induced current is generated in the detection residual current detection device on the secondary side, the value of the induced current is a residual current detection value, and the detection proportion is a proportion relation between the residual current detection value obtained by the residual current detection device and the residual current value actually generated in the detected device.

For example, a first control signal is input to make the self-test circuit enter a first conduction state, the total resistance value of the self-test circuit is a first value, the input voltage is a fixed value, a calculated value of the residual current in the first conduction state can be obtained according to ohm's law, the calculated value is compared with the detected value, and whether the detected value is consistent with the calculated value is judged. If the first control signal input is consistent with the second control signal input, the first control signal input is continuously maintained, the second control signal input is triggered, the self-checking circuit enters a second conduction state, the total resistance value of the self-checking circuit is changed into a second value, the input voltage of the self-checking circuit is unchanged, and the calculated value of the residual current in the second conduction state can be obtained according to ohm's law. And calculating a first ratio between the residual current detection value in the first conduction state and the residual current detection value in the second conduction state, and a second ratio between the residual current calculation value in the first conduction state and the residual current calculation value in the second conduction state, and judging whether the first ratio and the second ratio are consistent to judge whether the detection ratio of the residual current detection device is abnormal. In the present embodiment, the consistency means the same or the error is within a preset range.

The self-test circuit of the present embodiment inputs a test voltage through a first terminal 1; a current loop is formed with the first terminal 1 by connecting the second terminal 2 with a reference ground; inputting a first control signal through a third terminal 3 to make the self-checking circuit enter a first conduction state to detect whether a residual current is generated and determine whether the value of the residual current is abnormal; on the basis that the third terminal 3 keeps inputting the first control signal through the fourth terminal 4, the second control signal is input, so that the self-checking circuit enters a second conduction state, whether the detection proportion of the residual current detection device is abnormal or not is detected, the self-checking can be firstly carried out before the residual current detection device is formally used, the accuracy of a detection result is ensured, and the influence on the normal operation of the converter due to the fact that the residual current detection device cannot accurately and precisely detect the residual current is avoided.

Example 2

In this embodiment, another self-test circuit is provided, and fig. 2 is a structural diagram of a self-test circuit according to an embodiment of the present invention, as shown in fig. 2, the self-test circuit includes: a first detection branch 11, which is arranged between the first terminal 1 and the second terminal 2, is conducted under the control of a first control signal, and enables the self-detection circuit to enter a first conduction state; and the second detection branch 12 is connected in parallel with the first detection branch 11, and after the first detection branch 11 is turned on, the second detection branch 12 is turned on under the control of a second control signal, so that the self-detection circuit enters a second conduction state. By controlling the conduction states of the first detection branch 11 and the second detection branch 12, the self-detection circuit can enter a first conduction state or a second conduction state, so that the self-detection circuit has different total resistance values, and different residual current values can be detected, so as to judge whether the residual current value is abnormal or not and judge whether the detection ratio is abnormal or not. The first detection branch 11 and the second detection branch 12 at least include one resistor to realize switching of different resistance values. At least one of the resistances of the first detecting branch 11 or the second detecting branch 12 is a variable resistance so as to change the total resistance value for performing a plurality of measurements. In this embodiment, the first sensing branch 11 includes a first resistor R1, the second sensing branch 12 includes a second resistor R2, and the second resistor R2 is a variable resistor.

In order to control the conduction states of the first detecting branch 11 and the second detecting branch 12, as shown in fig. 2, the self-test circuit includes: a first switch Q1, disposed between the connection point of the first detection branch 11 and the second detection branch 12 and the second terminal 2, for conducting under the control of the first control signal, so as to control the conduction of the first detection branch 11; the second switch Q2 is disposed on the second detecting branch 12, and is configured to be turned on under the control of the second control signal based on the turning on of the first switch Q1, so as to control the turning on of the second detecting branch 12. The first switch Q1 and the second switch Q2 are used for controlling the first detection branch 11 to be conducted independently, or the first detection branch 11 and the second detection branch 12 are conducted simultaneously, so that different resistances are controlled to be conducted, and the total resistance value of the self-detection circuit is controlled to be switched.

The existing residual current detection device generally comprises two types, wherein one type is a threading type residual current detection device, a detection lead needs to be penetrated through the inside of the detection device, during detection, detection voltage is input from a first terminal 1, current passes through the inside of the detection lead, a magnetic field can be generated around the detection lead, and the residual current detection device detects generated induced current so as to realize the purpose of residual current detection; the other type of the on-board residual current detection device is provided with a wire, a detection wire is arranged in the on-board residual current detection device, one end of the detection wire inputs a certain voltage, the other end of the detection wire is connected with a detection voltage input terminal in a detected loop, when the detected loop is electrified, current passes through the detection wire arranged on the residual current detection device, a magnetic field can be generated around the detection wire, and the residual current detection device detects generated induced current so as to realize the purpose of detecting the residual current.

The self-checking circuit of this embodiment can be applied to threading type residual current detection device, when being applied to from taking wire type board to carry residual current detection device, the self-checking circuit still includes: a third switch K disposed between a connection point of the first detection branch 11 and the second detection branch 12 and the first terminal 1; and a fifth terminal for inputting a third control signal to turn on the third switch K. And controlling whether the self-checking circuit is electrified or not by switching off or switching on the third switch K.

The self-checking circuit of this embodiment both can also be applied to threading type residual current detection device, when being applied to threading type residual current detection device, the self-checking circuit still includes: the first wiring terminal J1-1 and the second wiring terminal J1-2 are arranged between a connection point of the first detection branch 11 and the second detection branch 12 and the first terminal 1, the first wiring terminal J1-1 is used for connecting a first end of a detection lead of the residual current detection device, and the second wiring terminal J1-2 is used for connecting a second end of the detection lead.

Fig. 3 is a structural diagram of a self-checking circuit according to another embodiment of the present invention, after a first control signal or a second control signal is input, a voltage value of the first control signal or the second control signal may not reach a turn-on voltage of the first switch Q1 or the second switch Q2, so that the first switch Q1 or the second switch Q2 cannot be turned on smoothly, as shown in fig. 3, the self-checking circuit further includes: the conversion module is used for converting a first control signal input by the third terminal 3 to obtain a first conversion signal, and the first conversion signal is used for controlling the self-checking circuit to enter a first conduction state; the conversion module is further configured to convert a second control signal input by the fourth terminal 4 to obtain a second conversion signal, where the second conversion signal is used to control the self-checking circuit to enter a second conduction state. Specifically, if the voltage value of the first control signal or the second control signal is too low, the conversion module may boost the voltage value of the first control signal or the second control signal, so as to ensure that the first switch Q1 or the second switch Q2 is smoothly turned on after the first control signal or the second control signal is input.

Example 3

The present embodiment provides a self-test method applied to the self-test circuit in the foregoing embodiment, and fig. 4 is a flowchart of the self-test method according to the embodiment of the present invention, as shown in fig. 4, the method includes:

s101, a first control signal input is triggered to enable the self-checking circuit to enter a first conduction state so as to judge whether the detection precision of the residual current detection device is abnormal or not.

After the self-checking circuit enters the first conduction state, the resistance value of the self-checking circuit is a first value, a calculated value of the residual current can be obtained according to the first value and the detection voltage, and the calculated value is compared with a detected value of the residual current, so that whether the detection precision of the residual current detection device is abnormal or not can be judged.

S102, if the detection precision of the residual current detection device is normal, a second control signal input is triggered on the basis of maintaining the first control signal input, so that the self-detection circuit enters a second conduction state to judge whether the detection proportion of the residual current detection device is abnormal or not.

In the step S102, the residual current detection value and the calculated value in the first conduction state are already obtained, the self-checking circuit is brought into the second conduction state by triggering the input of the second control signal, and a residual current detection value and a calculated value can be obtained again.

In the self-checking method of the embodiment, the self-checking circuit enters the first conduction state by triggering the input of the first control signal, so as to judge whether the detection precision of the residual current detection device is abnormal or not; if the detection precision of the residual current detection device is normal, the second control signal input is triggered on the basis of maintaining the first control signal input, so that the self-checking circuit enters a second conduction state to judge whether the detection proportion of the residual current detection device is abnormal or not, the self-checking can be performed before the residual current detection device is formally used, the accuracy of a detection result is ensured, and the influence on the normal operation of the converter due to the fact that the residual current detection device cannot accurately and precisely detect the residual current is avoided.

Example 4

The present embodiment provides another self-checking method, which determines whether the detection precision of the residual current detection apparatus is abnormal based on the foregoing embodiment, and specifically includes: judging whether the residual current detection value is consistent with the calculated value; if yes, judging that the detection precision of the residual current detection device is normal; if not, the detection precision of the residual current detection device is judged to be abnormal. Judging whether the detection proportion of the residual current detection device is abnormal or not, specifically comprising: respectively calculating a first ratio between a residual current detection value in a first conduction state and a residual current detection value in a second conduction state and a second ratio between a residual current calculation value in the first conduction state and the residual current detection value in the second conduction state according to a current calculation formula; judging whether the first ratio is consistent with the second ratio; if yes, judging that the detection proportion of the residual current detection device is normal; if not, the detection proportion of the residual current detection device is judged to be abnormal. Wherein, consistent means the same, or the error is within a preset range. By the scheme, whether the detection precision of the residual current detection device is abnormal or not and whether the detection proportion is abnormal or not can be accurately judged.

For example, when designing a circuit: the first detection branch comprises a first resistor R1, the resistance of the first resistor R1 is 470 ohms, the second detection branch comprises a second resistor R2, and the resistance of the second resistor R2 is 470 ohms. The detection voltage is VCC, and the saturation voltage of the first switch is V_CEWhen only the first resistor R1 is connected to the loop, the detection voltage VCC is connected to the reference ground through the first resistor R1 and the first switch to form a current loop, and the current of the loop can be obtained by ohm's law:

when the resistors R1 and R4 are connected in parallel and then connected into a circuit, the detection voltage VCC is connected to the reference ground through a parallel circuit formed by the first resistor R1 and the second resistor R2 and the first switch to form a current loop,

the current of the loop can be obtained from ohm's law:

through the scheme, the calculated residual current values in the first conduction state and the second conduction state are obtained.

In the specific implementation process, the situation that the residual current cannot be detected may also occur, if the residual current is not detected, it is indicated that the residual current detection device is abnormally turned on, and a short circuit or an open circuit may occur inside, so before determining whether the detection accuracy of the residual current detection device is abnormal, the method further includes: judging whether residual current is detected; if not, judging that the residual current detection device is abnormal in conduction; if yes, triggering and judging whether the detection precision of the residual current detection device is abnormal or not. Through the scheme, whether the residual current detection device is normally conducted or not can be detected, and when the residual current detection device is abnormally conducted and short circuit or open circuit possibly occurs in the residual current detection device, the residual current detection device can timely find and process the residual current detection device so as to avoid inaccurate detection results in formal use.

In a specific implementation process, triggering a first control signal input to enable a self-checking circuit to enter a first conduction state includes: and triggering the input of a first control signal to enable the first switch to be conducted, further controlling the conduction of the first detection branch circuit and enabling the self-detection circuit to enter a first conduction state. Triggering the second control signal input on the basis of maintaining the first control signal input to enable the self-checking circuit to enter a second conducting state, and the method comprises the following steps: and triggering a second control signal input to enable the second switch to be conducted, further controlling the conduction of the second detection branch circuit, and enabling the self-detection circuit to enter a second conduction state. Through first detected signal and second detected signal, can accurate control first switch and the second switch on the opportunity, and then the accurate conducting state who switches over whole self-checking circuit.

The self-checking circuit of this embodiment can be applied to threading type residual current detection device, when being applied to from taking wire type board to carry residual current detection device, before triggering first control signal input, above-mentioned method still includes: triggering a third control signal input to turn on the third switch; the third switch is arranged between the connecting point of the first detection branch and the second detection branch and the first terminal of the self-checking circuit. The conducting state of the whole self-checking circuit is controllable by arranging the third switch and a third control signal for controlling the third switch to be conducted.

Example 5

The present embodiment provides a self-test circuit, as shown in fig. 2 mentioned above, comprising: 5 external terminals, respectively: a first terminal 1 for inputting an external detection voltage VCC or a detection voltage Test _ Out outputted by the residual current detection device, a second terminal 2 for connecting to a ground GND, a third terminal 3 for inputting a first control signal S1, a fourth pin 4 for inputting a second control signal S2, and a fifth terminal 5 for inputting a third control signal S3. Wherein the first terminal 1 functions as: when the threading type onboard residual current detection device is selected, an external detection voltage VCC is input into the first terminal 1, the first terminal J1_1 and the second terminal J1_2 in the self-detection circuit are respectively connected with two ends of a detection lead of the residual current detection device, and the self-detection function can be realized by sequentially triggering a first control signal S1 and a second control signal S2; when the onboard residual current detection device with the lead wire is selected, the first terminal 1 inputs detection voltage Test _ Out output by the residual current detection device, and sequentially triggers a third control signal S3, a first control signal S1 and a second control signal S2 to realize a self-detection function. The first control signal S1 is used to control the on and off of the first switch; the second control signal S2 is used to control the on or off of the second switch; the third control signal S3 controls the turning on and off of the third switch. The calculated value of the residual current is determined by the known resistances of the first resistor R1 and the second resistor R2 and the first resistor R1 and the second resistor R2.

The self-checking circuit is independently packaged into a module, the plugging and unplugging can be realized only by mounting terminals for outputting detection voltage, grounding voltage, a first control signal S1, a second control signal S2 and a third control signal S3 on a control mainboard of the converter, and the component is mounted in a matched manner according to the actual application requirements. The module is applied to the intelligent converter, the problem that frequent error protection or overlarge residual current cannot be protected due to the abnormal function of the residual current detection device is solved, and safety accidents are avoided.

The embodiment further provides a self-checking method, which is applied to a threading type onboard residual current detection device, and fig. 5 is a flowchart of a detection method according to another embodiment of the present invention, as shown in fig. 5, the method includes:

and S11, controlling the converter to be powered on.

S12, the first control signal is triggered to turn on the first switch. The first control signal is a high level signal.

S13, it is determined whether a residual current is detected, and if not, step S14 is performed, and if yes, step S15 is performed. After the first switch is conducted, the detection voltage VCC forms a loop from the first resistor and the first switch to a reference ground, namely, residual current should flow through the residual current detection device, if the residual current exists, the device is normal in function, and if the residual current is not detected, the main control circuit reports a fault, the converter does not operate, and a designer is prompted to troubleshoot the problem.

S14, reporting the conduction abnormality of the residual current detecting device.

S15, judging whether the residual current detection value is consistent with the calculated value; if not, go to step S16; if so, step S17 is performed. After the first switch is turned on, a calculated value of the residual current can be calculated in advance through the known resistance value of the first resistor, if the detected value of the residual current is consistent with the calculated value, the detection precision of the residual current detection device is normal, and if not, the detection precision of the residual current detection device is abnormal. Wherein, consistent means the same or the error is within a preset range.

And S16, reporting that the detection precision of the residual current detection device is abnormal. And after the detection accuracy of the residual current detection device is judged to be abnormal, controlling the converter to be temporarily out of operation and reporting a fault.

S17, the control signal is triggered to turn on the second switch. The second control signal is a high level signal.

S18, judging whether the residual current detection ratio is abnormal; if so, go to step S19; if not, step S110 is executed. After the second switch is switched on, the first resistor and the second resistor are connected in parallel, the resistor is reduced, the residual current flowing through the residual current detection device is increased, the calculated value of the residual current value at the moment can be calculated in advance according to the known resistance values of the first resistor and the second resistor, and the calculated value is compared with the detected value of the residual current detected when the first switch is switched on alone, so that whether the detection proportion of the residual current detection device is abnormal or not can be determined; if the residual current is abnormal, reporting that the detection proportion of the residual current detection device is abnormal; and if the residual current detection device is normal, judging that the residual current detection device works normally, stopping outputting the first control signal and the second control signal, and finishing self-checking. After the residual current detection device finishes self-checking, the converter can be controlled to normally start and operate.

For example, the first resistor is set to 470 ohms and the second resistor is set to 470 ohms when designing the circuit. The detection voltage is VCC, and the saturation voltage of the first switch is V_CEWhen only the first resistor is connected into the loop, the detection voltage VCC is connected to the reference ground through the first resistor and the first switch to form a current loop, and the current of the loop can be obtained by ohm's law:

when the first resistor and the second resistor are connected in parallel and then connected into a circuit, the detection voltage VCC is connected to the reference ground through a parallel circuit formed by the first resistor and the second resistor and the first switch to form a current loop,

the current of the loop can be obtained from ohm's law:

through the scheme, the calculated value of the residual current when the first switch is independently conducted and the first switch and the second switch are simultaneously conducted is obtained.

S19, reporting that the detection ratio of the residual current detection device is abnormal.

And S20, stopping outputting the first control signal and the second control signal, and completing self-checking.

The present embodiment further provides another self-testing method, which is applied to a self-leaded on-board residual current testing device, and fig. 6 is a flowchart of a testing method according to another embodiment of the present invention, as shown in fig. 6, the method includes:

and S21, controlling the converter to be powered on.

S22, the third control signal is triggered to turn on the third switch.

S23, the first control signal is triggered to turn on the first switch. The first control signal is a high level signal.

S24, it is determined whether a residual current is detected, and if not, step S25 is performed, and if yes, step S26 is performed. After the first switch is conducted, the detection voltage VCC forms a loop from the first resistor and the first switch to a reference ground, namely, residual current should flow through the residual current detection device, if the residual current exists, the device is normal in function, and if the residual current is not detected, the main control circuit reports a fault, the converter does not operate, and a designer is prompted to troubleshoot the problem.

S25, reporting the conduction abnormality of the residual current detecting device.

S26, judging whether the residual current detection value is consistent with the calculated value; if not, go to step S27; if so, step S28 is performed. After the first switch is turned on, a calculated value of the residual current can be calculated in advance through the known resistance value of the first resistor, if the detected value of the residual current is consistent with the calculated value, the detection precision of the residual current detection device is normal, and if not, the detection precision of the residual current detection device is abnormal. Wherein, consistent means the same or the error is within a preset range.

And S27, reporting that the detection precision of the residual current detection device is abnormal. And after the detection accuracy of the residual current detection device is judged to be abnormal, controlling the converter to be temporarily out of operation and reporting a fault.

S28, the control signal is triggered to turn on the second switch. The second control signal is a high level signal.

S29, judging whether the residual current detection ratio is abnormal; if yes, go to step S210; if not, step S211 is performed. After the second switch is switched on, the first resistor and the second resistor are connected in parallel, the resistor is reduced, the residual current flowing through the residual current detection device is increased, the calculated value of the residual current value at the moment can be calculated in advance according to the known resistance values of the first resistor and the second resistor, and the calculated value is compared with the detected value of the residual current detected when the first switch is switched on alone, so that whether the detection proportion of the residual current detection device is abnormal or not can be determined; if the residual current is abnormal, reporting that the detection proportion of the residual current detection device is abnormal; and if the residual current detection device is normal, judging that the residual current detection device works normally, stopping outputting the first control signal and the second control signal, and finishing self-checking. After the residual current detection device finishes self-checking, the converter can be controlled to normally start and operate.

S210, reporting the detection proportion abnormity of the residual current detection device.

And S211, stopping outputting the first control signal and the second control signal, and completing self-checking.

Through the self-checking method of the embodiment, the problem that frequent error protection or overlarge residual current is not protected due to the abnormal function of the residual current detection device can be solved, and safety accidents are avoided.

Example 6

The present embodiment provides a residual current detection device, including the above-mentioned self-checking circuit, for detecting the residual current detection device before formal use, so as to ensure the accuracy of the detection result of the residual current detection device.

Example 7

The embodiment provides a converter, which comprises the residual current detection device and is used for accurately detecting the residual current of the converter so as to ensure the safe and stable operation of the converter.

Example 8

The present embodiment provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the above-described self-test method.

The above-described embodiments of the apparatus are merely illustrative, wherein the modules described as separate parts may or may not be physically separate, and the parts displayed as modules may or may not be physical modules, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (18)

1. A self-test circuit for use in a residual current detection device, the self-test circuit comprising:

a first terminal for inputting a detection voltage;

a second terminal connected to a reference ground;

a third terminal for inputting a first control signal to make the self-checking circuit enter a first conduction state to detect whether the detection precision of the residual current detection device is abnormal;

a fourth terminal, which inputs a second control signal on the basis of maintaining the first control signal input from the third terminal, so that the self-checking circuit enters a second conduction state to detect whether the detection ratio of the residual current detection device is abnormal or not; wherein the detection proportion is a proportional relation between a residual current detection value obtained by detection of the residual current detection device and a residual current value actually generated in the detected device.

2. The circuit of claim 1, wherein the self-test circuit comprises:

the first detection branch circuit is arranged between the first terminal and the second terminal and used for conducting under the control of the first control signal so as to enable the self-detection circuit to enter a first conducting state;

and the second detection branch is connected with the first detection branch in parallel and is used for being switched on under the control of the second control signal after the first detection branch is switched on, so that the self-detection circuit enters a second conduction state.

3. The circuit of claim 2, wherein at least one of the first detection branch and the second detection branch comprises a resistor.

4. The circuit of claim 3, wherein at least one of the resistances in the first or second detection branches is a variable resistance.

5. The circuit of claim 2, wherein the self-test circuit further comprises:

the first switch is arranged between a connecting point of the first detection branch and the second terminal and is used for conducting under the control of the first control signal so as to control the conduction of the first detection branch;

and the second switch is arranged on the second detection branch and is used for conducting under the control of the second control signal on the basis of conducting the first switch, so as to control the conduction of the second detection branch.

6. The circuit of claim 2, wherein the self-test circuit further comprises:

a third switch disposed between a connection point of the first detection branch and the second detection branch and the first terminal;

and a fifth terminal for inputting a third control signal to turn on the third switch.

7. The circuit of claim 2, wherein the self-test circuit further comprises:

first binding post and second binding post, first binding post with second binding post sets up first detection branch road with the second detects the junction point on branch road with between the first terminal, first binding post is used for connecting residual current detection device's the first end of detection wire, second binding post is used for connecting the second end of detection wire.

8. The circuit of claim 1, wherein the self-test circuit further comprises:

the switching module is used for switching a first control signal input by a third terminal to obtain a first switching signal, and the first switching signal is used for controlling the self-checking circuit to enter a first conduction state;

the conversion module is further configured to convert a second control signal input by the fourth terminal to obtain a second conversion signal, where the second conversion signal is used to control the self-checking circuit to enter a second conduction state.

9. A residual current detection device comprising the self-test circuit according to any one of claims 1 to 8.

10. A current transformer comprising the residual current detecting device according to claim 9.

11. A self-test method applied to the self-test circuit according to any one of claims 1 to 8, the method comprising:

triggering a first control signal input to enable the self-checking circuit to enter a first conduction state so as to judge whether the detection precision of the residual current detection device is abnormal or not;

if the detection precision of the residual current detection device is normal, on the basis of maintaining the input of the first control signal, triggering the input of a second control signal to enable the self-detection circuit to enter a second conduction state so as to judge whether the detection proportion of the residual current detection device is abnormal or not.

12. The method according to claim 11, wherein determining whether the detection accuracy of the residual current detection device is abnormal comprises:

judging whether the residual current detection value is consistent with the calculated value;

if yes, judging that the detection precision of the residual current detection device is normal;

and if not, judging that the detection precision of the residual current detection device is abnormal.

13. The method according to claim 11, wherein determining whether the detection ratio of the residual current detection device is abnormal comprises:

respectively calculating a first ratio between a residual current detection value in a first conduction state and a residual current detection value in a second conduction state, and a second ratio between a residual current calculation value in the first conduction state and a residual current calculation value in the second conduction state;

judging whether the first ratio is consistent with the second ratio;

if yes, judging that the detection proportion of the residual current detection device is normal;

if not, judging that the detection proportion of the residual current detection device is abnormal.

14. The method according to claim 11, wherein before determining whether the detection accuracy of the residual current detecting device is abnormal, the method further comprises:

judging whether residual current is detected;

if not, judging that the residual current detection device is abnormal in conduction;

if yes, triggering and judging whether the detection precision of the residual current detection device is abnormal or not.

15. The method of claim 11, wherein triggering a first control signal input to cause the self-test circuit to enter a first conductive state comprises:

and triggering a first control signal input to enable the first switch to be conducted, and further controlling the first detection branch circuit to be conducted, so that the self-detection circuit enters a first conduction state.

16. The method of claim 11, wherein triggering the second control signal input to cause the self-test circuit to enter the second conductive state upon assertion of the first control signal input comprises:

and triggering a second control signal input to enable the second switch to be conducted, and further controlling the conduction of the second detection branch circuit to enable the self-detection circuit to enter a second conduction state.

17. The method of claim 11, wherein prior to triggering the first control signal input to cause the self-test circuit to enter the first conductive state, the method further comprises:

triggering a third control signal input to turn on the third switch; the third switch is arranged between a connecting point of the first detection branch and the second detection branch and the first terminal of the self-checking circuit.

18. A computer-readable storage medium, on which a computer program is stored, which program, when being executed by a processor, carries out the method according to any one of claims 11 to 17.

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