Open circuit detection circuit and electric equipment

Abstract

The utility model discloses a circuit break detection circuit and electric equipment. The circuit break detection circuit comprises a sampling resistor connected with a circuit to be detected, a voltage detection circuit used for detecting the voltage of the sampling resistor, and multiple detection branches connected with the sampling resistor. The switching unit is used for switching on the detection branch when the voltage detection circuit detects that the voltage is zero; and when the detection branch is switched to be conducted and the detection voltage of the voltage detection circuit is not zero, the circuit to be detected is judged to be disconnected. Compared with the prior art, the detection circuit is provided with multiple detection branches, when the detection voltage of one detection branch is zero, the other detection branch is switched to be conducted, whether the detection voltage of the voltage detection circuit is zero is caused by the open circuit of the circuit to be detected or the overlarge resistance value can be identified, and the problem of misjudgment of the open circuit is avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to circuit fault detection, in particular to a circuit detection circuit and electric equipment. BACKGROUND

[0002] At present, the detection mode of sensor circuit break is mostly that the sampling resistor is directly connected in series with the sensor circuit, and the state of the sensor circuit is judged by detecting the current and voltage on the sampling resistor.

[0003] The patent with the patent number CN205541252U discloses an electrical fire alarm which alarms by sampling voltage and comparison. Here, by adding a conversion circuit for secondary detection, the detection of sensor circuit break can be more accurate.

[0004] The above scheme can improve the detection accuracy to some extent, but there is still a possibility of misjudgment. When detecting the voltage of the sampling resistor, two situations will cause the voltage on the sampling resistor to be 0. One is that the sensor circuit is broken, and since the sampling resistor is connected in series with the sensor circuit, the sampling resistor is also equivalent to being broken, so the voltage on the sampling resistor is 0.

[0005] The second is that the resistance value of the sensor circuit is too large. According to the principle of series voltage division, the voltage on the resistor is proportional to its resistance. When the resistance of the sensor circuit is much larger than that of the sampling resistor, the voltage on the sampling resistor will be pulled down to a very low level, which will cause the voltage sampling result of the sampling resistor to be 0.

[0006] The above second situation is not a sensor breakage fault, so misjudgment caused by the above second situation should be avoided in actual detection. Therefore, how to design a circuit detection circuit and electric equipment that can avoid misjudgment in sensor circuit detection is a technical problem to be solved in the industry. UTILITY MODEL CONTENTS

[0007] In view of the misjudgment problem in the prior art when detecting the sensor circuit break, the utility model provides a circuit detection circuit and electric equipment.

[0008] The technical scheme of the utility model provides a circuit detection circuit, which comprises a sampling resistor connected with a to-be-detected circuit, a voltage detection circuit for detecting the voltage at the sampling resistor, and a plurality of detection branches connected with the sampling resistor.

[0009] It also comprises a switching unit for switching on the detection branches when the voltage detected by the voltage detection circuit is 0.

[0010] When the detection branches are switched on, if the voltage detected by the voltage detection circuit is not 0, it is determined that the to-be-detected circuit is broken.

[0011] Further, a current limiting unit is connected in series between the sampling resistor and the voltage detection circuit, and the current limiting unit limits the current flowing into the voltage detection circuit to be less than a protection current threshold.

[0012] Further, at least one filtering circuit is connected between the sampling resistor and the voltage detection circuit.

[0013] Further, the detection branch is provided with two branches, and the switching unit is a relay.

[0014] The fixed contact of the relay is connected with the sampling resistor, and the two movable contacts of the relay are arranged in the two detection branches respectively.

[0015] Further, the detection branch includes a first detection branch and a second detection branch, the first detection branch is grounded relative to the other end of the sampling resistor, and the second detection branch is connected with a power supply of a preset voltage relative to the other end of the sampling resistor.

[0016] Further, the voltage detection circuit is a voltage detection chip.

[0017] Further, the current limiting unit is a current limiting resistor.

[0018] Further, the filtering circuit includes a first capacitor and a second capacitor.

[0019] One end of the first capacitor is connected between the voltage detection circuit and the current limiting unit, and the other end of the first capacitor is grounded.

[0020] One end of the second capacitor is connected between the sampling resistor and the current limiting unit, and the other end of the second capacitor is grounded.

[0021] The utility model further provides a kind of electric equipment, and the electric equipment has the above circuit breaker detection circuit.

[0022] Further, the electric equipment is an air conditioner.

[0023] Compared with prior art, the utility model at least has following beneficial effects:

[0024] The utility model is provided with multiple detection branches, when the voltage of one detection branch is zero, another detection branch is switched on, whether the zero voltage of voltage detection circuit is caused by the circuit to be measured being broken or resistance being too large can be identified, and the problem of false positive of broken circuit is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only represent some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0026] Figure 1 A circuit topology of the existing circuit for detecting a broken circuit;

[0027] Figure 2 A circuit topology of the existing circuit for detecting a broken circuit;

[0028] Figure 3 A detection flowchart of the whole utility model. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0030] Therefore, one feature described in the specification will be used to explain one feature of one embodiment of the present application, and it is not implied that each embodiment of the present application must have the described feature. In addition, it should be noted that the present specification describes many features. Although some features can be combined together to show possible system designs, these features can also be used in other combinations that are not explicitly described. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0031] The principles and structures of the present application will be described in detail below with reference to the drawings and embodiments.

[0032] Please refer to Figure 1 , at present, the way of detecting the broken circuit of the sensor circuit is mostly to connect the sampling resistor (i.e. the resistor marked with sampling in Figure 1 ) and the sensor circuit (the sensor circuit is connected through the detection port in Figure 1 ) in series, and to judge the state of the sensor circuit by detecting the current and voltage on the sampling resistor.

[0033] The above scheme can improve the detection accuracy to a certain extent, but there is also a possibility of misjudgment. When detecting the voltage of the sampling resistor, there are two cases that will cause the voltage on the sampling resistor to be 0. One is that the sensor circuit is broken, and since the sampling resistor is connected in series with the sensor circuit, the sampling resistor is also equivalent to being broken, so the voltage on the sampling resistor is 0;

[0034] Second, the sensor circuit resistance is too large, according to the circuit series voltage division principle, the voltage on the resistance is proportional to its resistance, when the sensor circuit resistance is much larger than the sampling resistance, the voltage on the sampling resistance will be pulled down to a very low level, which will cause the voltage sampling on the sampling resistance, the sampling result is 0 voltage;

[0035] The above second case is not a sensor circuit failure, so in actual detection, the misjudgment caused by the above second case should be avoided.

[0036] For the above problems, the utility model provides a circuit for detecting circuit, it includes with the sampling resistance of the circuit to be measured, the voltage detection circuit for detecting the voltage on the sampling resistance, and the multiway detection branch connected with the sampling resistance;

[0037] It also includes a switching unit for switching on the detection branch when the voltage detection circuit detects zero voltage;

[0038] When the switching detection branch is turned on, and the voltage detection circuit detects that the voltage is not zero, it is determined that the circuit to be measured is open circuit.

[0039] The above-mentioned circuit to be measured in the utility model is not limited to the sensor circuit, and can be adapted to other circuits that need to be detected for open circuit, and has a wider application scene compared with the traditional technical solution.

[0040] Based on the above setting, the principle for solving the problems in the prior art in the utility model is:

[0041] Multiple detection branches are provided, and the voltages connected on each detection branch are different from each other, some are grounded, some are connected to 3.3V power supply, and some are connected to 6.6V power supply. It needs to be explained that in the above detection branch setting, the sampling resistance is connected to the detection branch, that is, it is connected to one of the above 3.3V power supply, 6.6V power supply or ground. In the case of open circuit of the above circuit to be measured, the sampling resistance is open with the circuit to be measured, so when detecting the voltage at the sampling circuit, it is equivalent to directly detecting the voltage on the power supply connected thereto. For example, when the sampling resistance is connected to the ground through the detection branch, the voltage at the sampling resistance will be detected as 0V;

[0042] However, when the sampling resistance is connected to the 3.3V power supply through the detection branch, the voltage at the sampling resistance will be detected as 3.3V;

[0043] Similarly, when the sampling resistance is connected to the 6.6V power supply through the detection branch, the voltage at the sampling resistance will be detected as 6.6V;

[0044] However, for the case that the resistance of the to-be-tested circuit is too large, the root cause of the voltage of 0V on the sampling resistor is in series with the to-be-tested circuit, and since the voltage division in series is proportional to the resistance, when the resistance of the to-be-tested circuit is much larger than the sampling resistor, the voltage is all distributed to the to-be-tested circuit, and no matter what level of voltage is connected to the detection branch, the voltage of 0V will be obtained on the sampling resistor;

[0045] That is, for the utility model, when the sampling resistor is in an open circuit state, different voltage detection results will be obtained when the voltage at the sampling resistor is detected when different detection branches are switched, and therefore, whether the to-be-tested circuit connected to the sampling resistor is in an open circuit state or not can be determined according to the above scheme.

[0046] The specific detection result is that if the voltage detection circuit detects that the voltage is zero, different detection branches are switched on, and if the voltage detected by the voltage detection circuit is still zero at this time, it indicates that the resistance of the to-be-tested circuit is too large, otherwise, if the voltage detected by the voltage detection circuit is not zero at this time, it indicates that the to-be-tested circuit is in an open circuit state.

[0047] Meanwhile, in order to further improve the accuracy of the detection result, multiple detection branches are arranged in the utility model, which are used for multiple test detection results, and whether the voltage detection circuit obtains different voltage sampling results under each detection branch, so as to avoid the misjudgment caused by other problems when switching once.

[0048] It can be seen that the utility model has at least the following beneficial effects through the above scheme:

[0049] The utility model sets multiple detection branches, and when the voltage detected by one detection branch is zero, another detection branch is switched on, so that whether the voltage detected by the voltage detection circuit is zero due to the open circuit of the to-be-tested circuit or the too large resistance of the to-be-tested circuit can be identified, and the problem of misjudgment of the open circuit is avoided.

[0050] Further, in the preferred embodiment of the utility model, the above detection branch is provided with two branches, and the above switching unit is a relay;

[0051] The fixed contact of the relay is connected with the sampling resistor, and the two movable contacts of the relay are arranged in the two detection branches respectively.

[0052] Based on the arrangement of the above relay, the detection branch in the utility model comprises a first detection branch and a second detection branch, wherein the other end of the first detection branch relative to the sampling resistor is grounded, and the other end of the second detection branch relative to the sampling resistor is connected with a power supply of a preset voltage.

[0053] Please refer to Figure 2The above relay, namely the switching unit, has three contacts, wherein contact 1 is a fixed contact, and contact 2 and contact 3 are both movable contacts; the two detection branches correspond to the connection of contact 1 and contact 2, at this time, one end of the sampling resistor is connected to the to-be-detected circuit through the detection port of the needle seat, and the other end of the sampling resistor is grounded;

[0054] and the connection of contact 1 and contact 3, at this time, one end of the sampling resistor is connected to the to-be-detected circuit through the detection port of the needle seat, and the other end of the sampling resistor is connected to a 2.5V power supply;

[0055] The first detection branch corresponds to the connection of contact 1 and contact 2, and the second detection branch corresponds to the connection of contact 1 and contact 3; when the voltage detection circuit detects the voltage, the actual detected voltage is the voltage between the sampling resistor and the to-be-detected circuit, namely the voltage between the sampling resistor marked in the figure and the needle seat; Figure 2 Figure 2 The voltage between the sampling resistor marked in the figure and the needle seat;

[0056] For the case that the to-be-detected circuit is in an open circuit state, after the sampling resistor is connected in series with the to-be-detected circuit, the sampling resistor and the to-be-detected circuit become in an open circuit state, and the current in the to-be-detected circuit cannot flow into the sampling resistor, so that the power supply in the detection branch is equivalent to being directly connected to the voltage detection circuit through the sampling resistor;

[0057] In this case, contact 1 and contact 2 are connected, and at this time, the voltage detection circuit obtains a voltage of 0V which is the ground voltage of the first detection branch;

[0058] Contact 1 and contact 3 are connected, and at this time, the voltage detection circuit obtains a voltage of 2.5V which is the ground voltage of the second detection branch;

[0059] For the case that the resistance value of the to-be-detected circuit is too large, after the sampling resistor is connected in series with the to-be-detected circuit, due to the principle of series voltage division, namely the voltage division of each resistor in the series circuit is proportional to the resistance value, when the resistance value of the to-be-detected circuit is too large and far exceeds the resistance value of the sampling resistor, the sampling resistor almost does not divide the voltage, namely the voltage drop on the sampling resistor is 0V;

[0060] In this case, whether contact 1 and contact 2 are connected or contact 1 and contact 3 are connected, due to the large difference between the resistance value of the to-be-detected circuit and the resistance value of the sampling resistor, the voltage on the sampling resistor will always be 0V.

[0061] That is, in this case, the voltage detected by the voltage detection circuit will always be 0V, and the utility model can determine that the to-be-detected circuit does not have an open circuit fault, and the reason why the voltage detection circuit detects a voltage of 0V is that the resistance value of the to-be-detected circuit is too large, thereby causing a misjudgment problem.

[0062] It should be noted that the power supply of the preset voltage mentioned in the foregoing is the 2.5V power supply mentioned in the foregoing​Figure 2 The preset voltage in the utility model is not limited to 2.5V, and as long as there is a voltage change compared with the ground, the above detection effect can be achieved.

[0063] In addition, the above two detection branches are only a preferred embodiment of the utility model, and in other embodiments of the utility model, multiple detection branches can be arranged, and the conduction of each detection branch is controlled by the single-chip microcomputer, and the above anti-misjudgment effect can also be achieved. It should be noted that when multiple detection branches are arranged, the power supply voltage connected to the other end of the sampling resistor of each detection branch should be different, so that different voltage detection results can be obtained when different detection branches are switched on.

[0064] Further, the utility model also includes the current -limiting unit that is connected between the sampling resistor and the voltage detection circuit, and the current -limiting unit limits the current flowing into the voltage detection circuit to be less than the protection current threshold.

[0065] Specifically, in a preferred embodiment of the utility model, the above current -limiting unit adopts a current -limiting resistor.

[0066] Please refer to Figure 2 The above current -limiting resistor (i.e. Figure 2 The resistor marked with a current -limiting resistor is connected between the sampling resistor and the voltage detection circuit, and according to circuit principle analysis, the current in the circuit is inversely proportional to the total resistance value in the circuit, so after the current -limiting resistor is connected, the current in the circuit can be suppressed, thereby avoiding the problem that the voltage of the to-be-detected circuit is too high and causes adverse effects on the voltage detection circuit.

[0067] It should be pointed out that in order to achieve the purpose of protecting the voltage detection circuit, the above sampling resistor is not the only scheme, and for the utility model, it only needs to avoid the influence of high current on the subsequent voltage sampling circuit.

[0068] Based on the above principle, the current -limiting unit in the utility model can also be replaced by an optical coupler, which cannot achieve the effect of current limiting, but it can separate the voltage detection circuit from the to-be-detected circuit, thereby avoiding the adverse effects of high voltage and high current on the voltage detection circuit.

[0069] Further, the utility model also includes at least one filter circuit connected between the sampling resistor and the voltage detection circuit;

[0070] Specifically, in a preferred embodiment of the utility model, the above filter circuit includes a first capacitor and a second capacitor;

[0071] One end of the first capacitor is connected between the voltage detection circuit and the current -limiting unit, and the other end of the first capacitor is grounded;

[0072] One end of the second capacitor is connected between the sampling resistor and the current unit, and the other end of the second capacitor is grounded.

[0073] Please refer to Figure 2 The first capacitor and the second capacitor are marked in the attached Figure 2 Both of the capacitors are used for filtering, and one end of the first capacitor is connected between the voltage detection circuit and the current limiting unit, and the other end of the first capacitor is grounded.

[0074] One end of the second capacitor is connected between the sampling resistor and the current unit, and the other end of the second capacitor is grounded.

[0075] So that both of the capacitors can be used as Y capacitors to filter interference, thereby improving the accuracy of the voltage parameter detected by the voltage detection circuit.

[0076] Further, the voltage detection circuit in the utility model samples a voltage detection chip.

[0077] Please refer to Figure 2 The chip in the attached Figure 2 The chip is the voltage detection chip, which is used as the voltage detection circuit, and is connected between the sampling resistor and the needle seat through the current limiting unit, that is, the voltage to be sampled is the voltage between the sampling resistor and the circuit to be detected.

[0078] By detecting the change of the voltage on different detection branches, it can be determined whether the misjudgment occurs.

[0079] The voltage detection chip is only one preferred embodiment of the utility model, and in other embodiments of the utility model, a sampling circuit can also be arranged through an amplifier, which samples the voltage at the sampling resistor by using the amplification characteristics of the amplifier. Compared with the scheme of using the voltage detection chip, since the amplifier has the amplification characteristics, it can avoid the misjudgment condition that the voltage detected by the voltage detection circuit is 0 due to the fact that the resistance value of the circuit to be detected is too large and the voltage division on the sampling resistor is too small, and the reliability is higher.

[0080] Please refer to Figure 3 It is the overall detection flowchart of the utility model, and includes the following steps:

[0081] The chip detects the voltage at the sampling resistor in real time, wherein the chip is the voltage detection chip in the attached Figure 2

[0082] ​"whether the voltage is 0V", here is the first detection judgment, for judging whether the voltage detected by the voltage detection circuit at the sampling resistor is 0V, if not, the voltage detection circuit detects normally at this time, and the circuit to be detected can be directly determined to be free of open circuit problem, when it is determined to be yes, the step of "further detection" needs to be performed;

[0083] At this time, the "switching unit connects the sampling resistor to the 2.5V power supply", here the 2.5V power supply is the power supply connected to the second detection branch in the foregoing, and the first voltage detection is connected to the first detection branch by default. Only when the first voltage detection result is 0V, the switching of this action will be performed.

[0084] "the chip detects the voltage at the sampling resistor again", here is the detection process of the second voltage detection circuit;

[0085] "whether the voltage is 2.5V", here is the second voltage detection judgment, if it is determined to be no, according to the logic introduced in the foregoing, it can be determined that the resistance value of the sensor (the circuit to be detected in this embodiment is set as a sensor) is too large, otherwise, when it is determined to be yes, it can be determined that the sensor has an open circuit.

[0086] In summary, the utility model can realize the judgment of whether the circuit to be detected has an open circuit fault through the above-mentioned setting, compared with the prior art, the utility model has at least the following beneficial effects:

[0087] The utility model is provided with multiple detection branches, when the voltage detected by one detection branch is zero, another detection branch is switched on, it can be identified that the zero voltage detected by the voltage detection circuit is caused by the open circuit of the circuit to be detected or the too large resistance value, and the occurrence of the open circuit misjudgment problem is avoided.

[0088] The above-mentioned is only the preferred embodiment of the present application, and does not limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A circuit for detecting an open circuit, characterized in that The circuit comprises a sampling resistor connected to the circuit to be tested, a voltage detection circuit for detecting the voltage at the sampling resistor, and a plurality of detection branches connected to the sampling resistor; The circuit further comprises a switching unit for switching on the detection branches when the voltage detected by the voltage detection circuit is zero; When the switching unit switches on the detection branches, the voltage detection circuit detects that the voltage is not zero, and the circuit to be tested is determined to be broken.

2. The open circuit detection circuit of claim 1, wherein The circuit further comprises a current limiting unit connected in series between the sampling resistor and the voltage detection circuit, which limits the current flowing into the voltage detection circuit to be less than a protection current threshold.

3. The open circuit detection circuit of claim 2, wherein, The circuit further comprises at least one filtering circuit connected between the sampling resistor and the voltage detection circuit.

4. The open circuit detection circuit of claim 1, wherein, The detection branches are provided with two branches, and the switching unit is a relay; The fixed contact of the relay is connected to the sampling resistor, and the two movable contacts of the relay are respectively arranged in the two detection branches.

5. The open circuit detection circuit of claim 4, wherein, The detection branches comprise a first detection branch and a second detection branch, the first detection branch is grounded relative to the other end of the sampling resistor, and the second detection branch is connected to a power supply with a preset voltage relative to the other end of the sampling resistor.

6. The open circuit detection circuit of claim 1, wherein, The voltage detection circuit is a voltage detection chip.

7. The open circuit detection circuit of claim 2, wherein, The current limiting unit is a current limiting resistor.

8. The open circuit detection circuit of claim 3, wherein, The filtering circuit comprises a first capacitor and a second capacitor; One end of the first capacitor is connected between the voltage detection circuit and the current limiting unit, and the other end of the first capacitor is grounded. One end of the second capacitor is connected between the sampling resistor and the current limiting unit, and the other end of the second capacitor is grounded.

9. An electric device, characterized by The power consumption device has the broken circuit detection circuit according to any one of claims 1 to 8.

10. The powered device of claim 9, wherein, The power consumption device is an air conditioner.

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