Contactor detection system and detection method

Abstract

The invention discloses a detection system and a detection method of a contactor. According to the detection system, a first sampling module and a second sampling module are arranged between an input module and a control module. The first sampling module collects a first sampling signal corresponding to a power supply signal output by the input module, and the second sampling module collects a second sampling signal corresponding to a coil signal of the contactor. Then, the control module detects the actuation time of the contactor based on the first sampling signal and the second sampling signal. Therefore, an auxiliary contact, a cable and the like for detecting the contactor do not need to be added, the actuation time of the contactor only needs to be determined based on the collected sampling signal, the detection cost of the contactor is reduced, and meanwhile, the detection precision of the contactor is improved. Moreover, the connection of the low-voltage and low-current auxiliary contact is not added, so that the risk of high-voltage and low-voltage breakdown in the detection system is reduced, and the detection safety of the contactor is improved.

Description

Technical Field

[0001] The present application relates to the technical field of equipment detection, and in particular to a detection system and a detection method for a contactor. Background Art

[0002] When an electronic contactor is actually working, the time difference between the moment when the contactor control power supply is energized and the moment when the contactor contacts close the main circuit is turned on is usually called the contactor's pull-in time. The measurement of the contactor's pull-in time can be used to determine the operating status of the equipment. In this way, by regularly testing the contactor's pull-in time, potential faults and other problems that may exist in the contactor can be discovered in a timely manner.

[0003] Usually, the laboratory uses manual stopwatch measurement, oscilloscope measurement, special measuring instruments and other methods to measure the release time of the contactor. In actual industry, the closing time of the auxiliary contact of the contactor is usually used to equal the pull-in time of the main contact. However, there are two problems with this. The first is that the cost of the auxiliary contacts and cables is increased. The second is that the main circuit is high voltage and high current, and the signal of the auxiliary contact is low voltage and low current. There may be a risk of high and low voltage breakdown in actual use. Third, the auxiliary contact is connected with a small current. After long-term use, the impedance may increase and it may not be connected. Summary of the invention

[0004] The purpose of the present application is to provide a contactor detection system and detection method, so as to solve the problem of high cost and low safety of contactor detection in the prior art.

[0005] In order to achieve the above-mentioned object, the first aspect of the present application provides a contactor detection system, the detection system comprising an input module, a first sampling module, a second sampling module and a control module, wherein:

[0006] The first sampling module and the second sampling module are electrically connected to the input module respectively, the first sampling module is used to collect a first sampling signal corresponding to the power signal output by the input module, and the second sampling module is used to collect a second sampling signal corresponding to the coil signal of the contactor;

[0007] The control module is electrically connected to the first sampling module and the second sampling module to receive the first sampling signal and the second sampling signal of the first sampling module and the second sampling module, and detects the contactor's contact time based on the first sampling signal and the second sampling signal.

[0008] In the embodiment of the present application, the control module is used to:

[0009] Sampling the first sampling signal and the second sampling signal according to the set sampling frequency;

[0010] Determine the first time when the contactor starts to close according to the first sampling signal;

[0011] After the first time, determining a second time at which the contactor completes the pull-in according to second sampling signals collected at three adjacent sampling times;

[0012] The contactor's closing time is determined according to the first time and the second time.

[0013] In the embodiment of the present application, the three adjacent sampling times include a first sampling time, a second sampling time, and a third sampling time, the first sampling time is earlier than the second sampling time, and the second sampling time is earlier than the third sampling time;

[0014] in:

[0015] When the first sampling signal is greater than the set pull-in threshold, the current sampling time of the first sampling signal is determined as the first time when the contactor starts to pull in;

[0016] When the difference between the second sampling signal at the first sampling time and the second sampling signal at the second sampling time is greater than the first threshold, and the difference between the second sampling signal at the second sampling time and the second sampling signal at the third sampling time is greater than the second threshold, the control module determines the second sampling time as the second time.

[0017] In the embodiment of the present application, the first sampling module includes a first sampling circuit, and the first sampling circuit is connected between the input module and the control module.

[0018] In an embodiment of the present application, the first sampling circuit is a voltage divider sampling circuit, and the first sampling circuit includes a first operational amplifier and a voltage divider subcircuit connected to the input module;

[0019] The first operational amplifier includes a non-inverting input terminal connected to the output terminal of the voltage divider sub-circuit, an inverting input terminal connected to the ground, and an output terminal connected to the control module.

[0020] In an embodiment of the present application, the first sampling circuit is an amplifier sampling circuit, and the first sampling circuit includes a first operational amplifier;

[0021] The first operational amplifier includes a non-inverting input terminal connected to the input module, an inverting input terminal connected to the ground, and an output terminal connected to the control module.

[0022] In the embodiment of the present application, the second sampling module includes a first buck circuit, a second buck circuit, a drive circuit, a coil circuit, and a second sampling circuit;

[0023] The first step-down circuit is connected between the input module and the driving circuit, the driving circuit is connected to the coil circuit, the coil circuit is connected to the second sampling circuit, the second sampling circuit is connected to the control module, and the control module is connected to the driving circuit;

[0024] The second step-down circuit is connected between the first step-down circuit and the control module.

[0025] In an embodiment of the present application, the second sampling circuit is a low-side shunt sampling circuit, the coil circuit includes a coil and a sampling resistor, and the second sampling circuit includes a second operational amplifier;

[0026] The first end of the coil is connected to the driving circuit, the second end of the coil is connected to the first end of the sampling resistor, and the second end of the sampling resistor is grounded;

[0027] The second operational amplifier includes a non-inverting input terminal connected to the second end of the coil, an inverting input terminal connected to the ground, and an output terminal connected to the control module.

[0028] In an embodiment of the present application, the second sampling circuit is a high-side shunt sampling circuit, the coil circuit includes a coil and a sampling resistor, and the second sampling circuit includes a second operational amplifier;

[0029] The first end of the sampling resistor is connected to the driving circuit, the second end of the sampling resistor is connected to the first end of the coil, and the second end of the coil is grounded;

[0030] The second operational amplifier includes a non-inverting input terminal connected to the first terminal of the sampling resistor, an inverting input terminal connected to the second terminal of the sampling resistor, and an output terminal connected to the control module.

[0031] In an embodiment of the present application, the control module includes a single-chip microcomputer and an analog-to-digital converter, a first end of the analog-to-digital converter is connected to the first sampling module and the second sampling module, and a second end of the analog-to-digital converter is connected to the single-chip microcomputer.

[0032] In the embodiment of the present application, the control module is used to:

[0033] Triggering the analog-to-digital converter to collect the first sampling signal and the second sampling signal according to the set sampling time;

[0034] Performing data transfer on the first sampling signal and the second sampling signal through direct memory access, wherein when a set transfer cycle is completed, a data transfer interrupt is triggered, and an interrupt completion flag of the direct memory access is set to a first set value;

[0035] When it is detected that the interruption completion flag is the first set value, the interruption completion flag is set to the second set value, and the values ​​of the first sampling signal and the second sampling signal are recorded.

[0036] A second aspect of the present application provides a contactor detection method, the detection method comprising:

[0037] Acquire a first sampling signal obtained by sampling a power supply signal of the contactor and a second sampling signal obtained by sampling a coil signal of the contactor according to a set sampling frequency;

[0038] Determine the first time when the contactor starts to close according to the first sampling signal;

[0039] After the first time, determining a second time at which the contactor completes the pull-in according to second sampling signals collected at three adjacent sampling times;

[0040] The contactor's closing time is determined according to the first time and the second time.

[0041] In the embodiment of the present application, the three adjacent sampling times include a first sampling time, a second sampling time, and a third sampling time, the first sampling time is earlier than the second sampling time, and the second sampling time is earlier than the third sampling time;

[0042] Determining the first time when the contactor starts to close according to the first sampling signal includes:

[0043] When the first sampling signal is greater than the set pull-in threshold, the current sampling time of the first sampling signal is determined as the first time when the contactor starts to pull in;

[0044] After the first time, determining the second time at which the contactor completes the pull-in according to the second sampling signals collected at three adjacent sampling times includes:

[0045] When the difference between the second sampling signal at the first sampling time and the second sampling signal at the second sampling time is greater than the first threshold, and the difference between the second sampling signal at the second sampling time and the second sampling signal at the third sampling time is greater than the second threshold, the second sampling time is determined as the second time.

[0046] In an embodiment of the present application, obtaining a first sampling signal obtained by sampling a power signal of a contactor and a second sampling signal obtained by sampling a coil signal of a contactor at a set sampling frequency includes:

[0047] Triggering the analog-to-digital converter to collect the first sampling signal and the second sampling signal according to the set sampling time;

[0048] Data transfer is performed on the first sampling signal and the second sampling signal by direct memory access, wherein when a set transfer cycle is completed, a data transfer interrupt is triggered, and an interrupt completion flag of the direct memory access is set to a first set value;

[0049] When it is detected that the interrupt completion flag is the first set value, the interrupt completion flag is set to the second set value, and the values ​​of the first sampling signal and the second sampling signal are recorded.

[0050] The detection system of the contactor provided in the present application is provided with a first sampling module and a second sampling module between the input module and the control module. The first sampling module collects the first sampling signal corresponding to the power signal output by the input module, and the second sampling module collects the second sampling signal corresponding to the coil signal of the contactor. Then, the control module detects the contactor's pull-in time based on the first sampling signal and the second sampling signal. In this way, there is no need to add auxiliary contacts and cables for detecting the contactor. It is only necessary to determine the contactor's pull-in time based on the collected sampling signals, thereby reducing the detection cost of the contactor and improving the detection accuracy of the contactor. In addition, since there is no need to add the connection of the auxiliary contacts with low voltage and low current, the risk of high and low voltage breakdown in the detection system is reduced, and the safety of contactor detection is improved.

[0051] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0053] Figure 1 A schematic diagram of the structure of a contactor detection system provided in one embodiment of the present application;

[0054] Figure 2 A schematic structural diagram of a contactor detection system provided in another embodiment of the present application;

[0055] Figure 3 A schematic diagram of the structure of a voltage divider sampling circuit provided in an embodiment of the present application;

[0056] Figure 4 A schematic diagram of the structure of an amplifier sampling circuit provided in an embodiment of the present application;

[0057] Figure 5 A schematic diagram of the structure of a low-side current shunt sampling circuit provided in an embodiment of the present application;

[0058] Figure 6 A schematic diagram of the structure of a high-side current shunt sampling circuit provided in an embodiment of the present application;

[0059] Figure 7 A schematic diagram of the structure of a voltage divider sampling circuit provided in a specific embodiment of the present application;

[0060] Figure 8A schematic diagram of the structure of a low-side current shunt sampling circuit provided in a specific embodiment of the present application;

[0061] Fig. 9 This is a schematic diagram of the structure of a coil circuit provided in a specific embodiment of the present application;

[0062] Fig.10 A schematic diagram of the structure of a circuit in an input module provided in a specific embodiment of the present application;

[0063] Fig.11 This is a structural schematic diagram of a first step-down circuit provided in a specific embodiment of the present application;

[0064] Fig.12 This is a structural schematic diagram of a second step-down circuit provided in a specific embodiment of the present application;

[0065] Fig.13 A schematic diagram of the structure of a driving circuit provided in a specific embodiment of the present application;

[0066] Fig.14 A schematic flow chart of a contactor detection method provided in an embodiment of the present application;

[0067] Fig.15 A schematic diagram of a sampling signal provided in an embodiment of the present application.

[0068] Fig.16 A flowchart of a data transfer method provided in a specific embodiment of the present application;

[0069] Fig.17 The present invention is a flowchart of a method for detecting the contactor closing time provided in a specific embodiment of the present application. DETAILED DESCRIPTION

[0070] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0071] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0072] In the embodiments of the present application, it should be noted that, in this article, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0073] Moreover, the terms "comprises", "comprising" or any other variation thereof are intended to cover non-exclusive inclusion, so that an article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such article or device. In the absence of more restrictions, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the article or device comprising the element.

[0074] In the description of the embodiments of the present application, words such as "example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "example" or "for example" in the embodiments of the present application is not to be interpreted as being more preferred or having more advantages than another embodiment or design. The use of words such as "example" or "for example" is intended to present relative concepts in a clear manner.

[0075] In addition, the "plurality" in the embodiments of the present application refers to two or more than two. In view of this, in the embodiments of the present application, "plurality" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two or more. For example, including at least one means including one, two or more, and there is no limit on which ones are included. For example, including at least one of A, B and C, then A, B, C, A and B, A and C, B and C, or A, B and C can be included.

[0076] It should be noted that in the embodiments of the present application, "connection" can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0077] The first pole / first end of each transistor used in the embodiments of the present application is one of the source and the drain, and the second pole / second end of each transistor is the other of the source and the drain. Since the source and drain of the transistor can be symmetrical in structure, the source and drain thereof can be structurally indistinguishable, that is, the first pole / first end and the second pole / second end of the transistor in the embodiments of the present application can be structurally indistinguishable. Exemplarily, in the case where the transistor is a P-type transistor, the first pole / first end of the transistor is the source, and the second pole / second end is the drain; exemplarily, in the case where the transistor is an N-type transistor, the first pole / first end of the transistor is the drain, and the second pole / second end is the source.

[0078] In the circuit structure provided in the embodiments of the present application, the first node, the second node and other nodes do not represent actual existing components, but represent the junction points of related couplings in the circuit diagram, that is, these nodes are nodes formed by the equivalent junction points of related couplings in the circuit diagram.

[0079] The embodiment of the present application provides a contactor detection system, which is described in detail below.

[0080] See also Figure 1 , Figure 1 1 is a schematic diagram of a contactor detection system provided in an embodiment of the present application. The detection system may include an input module 100, a first sampling module 200, a second sampling module 300 and a control module 400. The first sampling module 200 and the second sampling module 300 are electrically connected to the input module 100, respectively. The control module 400 is electrically connected to the first sampling module 200 and the second sampling module 300.

[0081] In the embodiment of the present application, the input module 100 can generate a power signal for providing an input voltage to the detection system of the contactor, wherein the power signal can be an analog signal from a signal source, such as a sensor, a voltage source, and the like.

[0082] The input voltage is input to the first sampling module 200 and the second sampling module 300 respectively. The first sampling module 200 is used to collect the first sampling signal corresponding to the power signal output by the input module 100. The second sampling module 300 is used to collect the second sampling signal corresponding to the coil signal of the contactor.

[0083] The control module 400 can receive a first sampling signal corresponding to the power supply signal collected by the first sampling module 200. When the first sampling signal is greater than the set pull-in threshold, it indicates that the contactor starts to pull in. The set pull-in threshold refers to the threshold at which the contactor starts to pull in, and the set pull-in threshold can be determined according to the design requirements and application requirements of the contactor manufacturer. Therefore, the first time when the contactor starts to pull in can be obtained through the first sampling signal. The first time is the starting time of the contactor pulling in.

[0084] The control module 400 can also receive a second sampling signal corresponding to the coil signal of the contactor collected by the second sampling module 300. When the coil signal is applied to the coil of the contactor, the coil will generate a magnetic field, so that the main contact of the contactor is closed or opened, and the coil signal can reflect the state of the contactor. Therefore, the second time when the contactor completes the pull-in can be obtained through the second sampling signal, and the second time is the end time of the contactor pull-in.

[0085] As can be seen from the above, the control module 400 can obtain the first time representing the start of contactor closure and the second time representing the completion of contactor closure based on the first sampling signal and the second sampling signal. Therefore, the control module 400 can obtain the closure time of the contactor according to the first time corresponding to the first sampling signal and the second time corresponding to the second sampling signal.

[0086] The detection system of the contactor provided in the embodiment of the present application is provided with a first sampling module 200 and a second sampling module 300 between the input module 100 and the control module 400. The first sampling module 200 collects the first sampling signal corresponding to the power signal output by the input module 100, and the second sampling module 300 collects the second sampling signal corresponding to the coil signal of the contactor. Then, the control module 400 detects the contactor's pull-in time based on the first sampling signal and the second sampling signal. In this way, there is no need to add auxiliary contacts and cables for detecting the contactor. It is only necessary to determine the contactor's pull-in time based on the collected sampling signals, thereby reducing the detection cost of the contactor and improving the detection accuracy of the contactor. In addition, since there is no connection of auxiliary contacts with low voltage and low current, the risk of high and low voltage breakdown in the detection system is reduced, and the safety of contactor detection is improved.

[0087] Next, continue to Figure 1 Each module shown and the specific implementation methods that may be used in practical applications are described in detail.

[0088] See also Figure 2In some embodiments of the present application, the first sampling module 200 may include a first sampling circuit 210, and the first sampling circuit 210 is connected between the input module 100 and the control module 400. The first sampling circuit 210 is used to sample the power signal in the input module 100 to obtain a first sampling signal, and then transmit the first sampling signal to the control module 400.

[0089] The second sampling module 300 may include a first buck circuit 310, a second buck circuit 320, a drive circuit 330, a coil circuit 340, and a second sampling circuit 350. The first buck circuit 310 is connected between the input module 100 and the drive circuit 330, the drive circuit 330 is connected to the coil circuit 340, the coil circuit 340 is connected to the second sampling circuit 350, the second sampling circuit 350 is connected to the control module 400, and the control module 400 is connected to the drive circuit 330. The second buck circuit 320 is connected between the first buck circuit 310 and the control module 400.

[0090] The first step-down circuit 310 can step down the power signal of the input module 100 and input it to the second step-down circuit 320 and the drive circuit 330 respectively. The second step-down circuit 320 is used to supply power to the control module 400. The drive circuit 330 is used to provide a drive signal to the coil circuit 340 of the contactor so that the main contact of the contactor is closed or disconnected. After the second sampling circuit 350 obtains the coil signal of the coil circuit 340, it can output a second sampling signal to the control module 400.

[0091] In the embodiment of the present application, the type of the first sampling circuit 210 may include but is not limited to a voltage divider sampling circuit or an amplifier sampling circuit. The voltage divider sampling circuit divides the coil signal into a lower voltage and then performs signal acquisition to meet the subsequent circuit requirements. The amplifier sampling circuit is used to amplify the amplitude of the input signal and then perform signal acquisition to improve the strength of the coil signal or enhance the signal-to-noise ratio.

[0092] The voltage divider sampling circuit and the amplifier sampling circuit both include a first operational amplifier, which is used to generate a first sampling signal. The first operational amplifier generally includes a non-inverting input terminal (i.e., a positive input terminal, usually represented by +), an inverting input terminal (i.e., a negative input terminal, usually represented by -), and an output terminal. The non-inverting input terminal is usually connected to the front circuit to receive the coil signal and has a high input impedance. The inverting input terminal is usually connected to the output terminal of the operational amplifier to receive a feedback signal. By returning a portion of the output signal to the input terminal through the feedback circuit, the first operational amplifier can achieve the function of amplification and have stability. The output terminal is used to provide an amplified signal, and the amplified signal is usually proportional to the input signal. The output terminal generally has a lower output impedance so that it can drive subsequent circuits.

[0093] The following is a detailed description taking the voltage divider sampling circuit and the amplifier sampling circuit as examples.

[0094] See also Figure 3 , Figure 3 Schematic diagram of a voltage divider sampling circuit provided in an embodiment of the present application. In an embodiment of the present application, the first sampling circuit 210 may be a voltage divider sampling circuit, and the first sampling circuit 210 may include a first operational amplifier A1 and a voltage divider subcircuit connected to the input module 100. The voltage divider subcircuit is a circuit for dividing the voltage of a power supply signal, which is usually composed of a resistor network and is used to reduce the voltage of the power supply signal to a range suitable for subsequent circuit processing.

[0095] The first operational amplifier A1 may include a non-inverting input terminal a1 connected to the output terminal of the voltage divider subcircuit, an inverting input terminal b1 connected to the ground, and an output terminal c1 connected to the control module 400. The voltage divider subcircuit divides the power supply signal so that the power supply signal is reduced to a range suitable for the working range of the first operational amplifier A1. The non-inverting input terminal a1 of the first operational amplifier A1 receives the input signal provided by the voltage divider subcircuit. The inverting input terminal b1 of the first operational amplifier A1 is connected to the output terminal c1 through a feedback circuit, so that the first operational amplifier A1 forms a negative feedback. R11 and R12 are used to perform low-pass filtering on the input signal of the voltage divider subcircuit, and R14 and C11 are used to perform low-pass filtering on the output signal of the first operational amplifier A1. R13 is provided as a feedback resistor of the first operational amplifier A1 between the output terminal c1 and the inverting input terminal b1. The first operational amplifier A1 adjusts the output signal according to the size and polarity of the feedback signal so that the feedback signal is equal to or nearly equal to the input signal provided by the voltage divider subcircuit, thereby realizing the control and adjustment of the amplification factor. The output terminal c of the first operational amplifier A1 provides the amplified first sampling signal Vs to the control module 400 .

[0096] See also Figure 4 , Figure 4 Schematic diagram of the structure of an amplifier sampling circuit provided in an embodiment of the present application. In an embodiment of the present application, the first sampling circuit 210 may also be an amplifier sampling circuit, and the first sampling circuit 210 may include a first operational amplifier A1. The first operational amplifier A1 may include a non-inverting input terminal a1 connected to the input module 100, an inverting input terminal b1 connected to the ground, and an output terminal c1 connected to the control module 400.

[0097] The non-inverting input terminal a of the first operational amplifier A1 receives the power signal transmitted by the input module 100. The inverting input terminal b1 of the first operational amplifier A1 is connected to the output terminal c1 through a feedback circuit, so that the first operational amplifier A1 forms a negative feedback. R11 and R12 are used to perform low-pass filtering on the power signal of the input module, and R14 and C11 are used to perform low-pass filtering on the output signal of the first operational amplifier A1. R13, as a feedback resistor of the first operational amplifier A1, is arranged between the output terminal c1 and the inverting input terminal b1. The first operational amplifier A1 adjusts the output signal according to the size and polarity of the feedback signal so that the feedback signal is equal to or nearly equal to the power signal, thereby realizing the control and adjustment of the amplification factor. The output terminal c1 of the first operational amplifier A1 provides the amplified first sampling signal Vs to the control module 400.

[0098] In an embodiment of the present application, the coil circuit 340 may include a coil and a sampling resistor. The required power supply size can be obtained by the voltage drop across the sampling resistor, and the current signal can be converted into a voltage signal for subsequent measurement and processing. The types of the second sampling circuit 350 may include but are not limited to a low-side shunt sampling circuit and a high-side shunt sampling circuit. In the low-side shunt sampling circuit, the sampling resistor is arranged between the coil and the ground. The low-side shunt sampling circuit can directly measure the coil current. In the high-side shunt sampling circuit, the sampling resistor is arranged between the drive circuit 330 and the coil. The high-side shunt sampling circuit can measure the total current of the entire circuit without considering the voltage drop between the coil and the sampling resistor.

[0099] Both the low-side shunt sampling circuit and the high-side shunt sampling circuit include a second operational amplifier, which is used to generate a second sampling signal. The second operational amplifier also includes a non-inverting input terminal, an inverting input terminal and an output terminal. In the low-side shunt sampling circuit, the coil current can be converted into a voltage signal. The second operational amplifier amplifies the voltage signal to a range suitable for subsequent circuit processing. In the high-side shunt sampling circuit, the total current of the entire circuit can be converted into a voltage signal. Similarly, the second operational amplifier amplifies the voltage signal to a range suitable for subsequent circuit processing. In this way, amplification, regulation and filtering of the collected voltage signal can be achieved.

[0100] The following is a detailed description taking the low-side shunt sampling circuit and the high-side shunt sampling circuit as examples.

[0101] See also Figure 5 , Figure 5 Schematic diagram of a low-side shunt sampling circuit provided in an embodiment of the present application. In the embodiment of the present application, the second sampling circuit 350 may be a low-side shunt sampling circuit, the coil circuit 340 may include a coil L and a sampling resistor Rs, and the second sampling circuit 350 may include a second operational amplifier A2.

[0102] The first end of the coil L is connected to the driving circuit 330, the second end of the coil L is connected to the first end of the sampling resistor Rs, and the second end of the sampling resistor Rs is grounded. The sampling resistor Rs is connected between the coil L and the ground DGND to form a shunt circuit. When the current passes through the coil L and the sampling resistor Rs, the sampling resistor Rs generates a voltage drop proportional to the current, that is, the difference between V2 and V1.

[0103] The second operational amplifier A2 may include a non-inverting input terminal a2 connected to the second end of the coil, an inverting input terminal b2 connected to ground, and an output terminal c2 connected to the control module 400. The non-inverting input terminal a2 receives a voltage signal corresponding to the coil current. R21 and R22 are used to perform low-pass filtering on the input signal of the drive circuit, and R24 is a balancing resistor for eliminating the influence of the bias current on the output voltage. R23, as a feedback resistor of the second operational amplifier A2, is arranged between the output terminal c2 and the inverting input terminal b2. The inverting input terminal b2 is connected to the output terminal c2 through a feedback circuit, so that the second operational amplifier A2 forms a negative feedback. The output terminal c2 of the second operational amplifier A2 provides the amplified second sampling signal Vi to the control module 400.

[0104] See also Figure 6 , Figure 6 Schematic diagram of a high-side shunt sampling circuit provided in an embodiment of the present application. In an embodiment of the present application, the second sampling circuit 350 may also be a high-side shunt sampling circuit, the coil circuit 340 may include a coil L and a sampling resistor Rs, and the second sampling circuit 350 may include a second operational amplifier A2.

[0105] The first end of the sampling resistor Rs is connected to the driving circuit 330, the second end of the sampling resistor Rs is connected to the first end of the coil L, and the second end of the coil L is grounded. The sampling resistor Rs is connected between the driving circuit 330 and the coil L to form a voltage divider circuit. When current passes through the sampling resistor Rs, the sampling resistor Rs generates a voltage drop proportional to the current, that is, the difference between V2 and V1.

[0106] The second operational amplifier A2 may include a non-inverting input terminal a2 connected to the first end of the sampling resistor Rs, an inverting input terminal b2 connected to the second end of the sampling resistor Rs, and an output terminal c2 connected to the control module 400. R21 and R22 are used to perform low-pass filtering on the input signal of the driving circuit, and R24 is a balancing resistor for eliminating the influence of the bias current on the output voltage. R23 is a feedback resistor of the second operational amplifier A2, and is arranged between the output terminal c2 and the inverting input terminal b2. The non-inverting input terminal a2 receives a voltage signal corresponding to the total current of the circuit, and the inverting input terminal b2 is connected to the output terminal c2 through a feedback circuit, so that the second operational amplifier A2 forms a negative feedback. The output terminal c2 of the second operational amplifier A2 provides the amplified second sampling signal Vi to the control module 400.

[0107] In the embodiment of the present application, the control module 400 may include a single-chip microcomputer and an analog-to-digital converter (ADC), the first end of the ADC is connected to the first sampling module 200 and the second sampling module 300, and the second end of the analog-to-digital converter is connected to the single-chip microcomputer. In this way, the first sampling signal collected by the first sampling module 200 and the sampling signal collected by the second sampling module 300 can be converted from an analog signal to a digital signal through the ADC, and then the digital signal is input to the single-chip microcomputer, and then the single-chip microcomputer processes the digital signal to obtain the contactor's pull-in time.

[0108] The following is an example of a specific embodiment. Figure 2 Describe each module in.

[0109] See also Figure 7 , taking the voltage divider sampling circuit selected as the first sampling circuit 210 as an example. In a specific implementation, in the circuit, BR31 is a bridge rectifier, connected to the power line PowerL and the neutral line PowerN of the input module 100, and is used to rectify the AC power signal of the input module. R31, R32, R33, R34 and R35 form a step-down subcircuit. D31 is a switching diode, which is used to prevent overvoltage and negative pressure and other functions. R36 and R37 form a low-pass filter. A1, R38, R39 and C32 are a conditioning signal subcircuit. R39 and C33 form a low-pass filter. Finally, the first sampling signal Vs is output and enters the control module 400.

[0110] See also Figure 8, taking the second sampling circuit 350 as an example, a low-side shunt sampling circuit is selected. In a specific implementation, a second operational amplifier A2 and a third operational amplifier A3 are included. This implementation adds an active filtering circuit including a third operational amplifier A3 on the basis of the above-mentioned second sampling circuit, which is used to eliminate the noise of the second sampling circuit. After the output signal of the second operational amplifier A2 is actively filtered, a more accurate second sampling signal Vi can be obtained.

[0111] See also Fig. 9 In a specific implementation, terminal J51 is connected to the coil, diode D51 provides freewheeling current to the coil, transistor Q51 controls the on and off of the coil, R51 is a driving resistor to prevent Q51 from oscillating, R52 provides a discharge path for the GS junction capacitance of the MOS to prevent damage to the driving circuit, R53 is connected in series with the coil, and the output IA voltage divided by R53 is the coil current.

[0112] See also Fig.10 In a specific implementation, the part with terminal J61 as input and VB as output is the electromagnetic compatibility (EMC) circuit of the input voltage part. The variable resistor RV61 and the resistor R61 form an EMS circuit to prevent external high-voltage interference and damage to the product. Inductor L61, capacitor CX61, capacitor CX62, and inductor L62 form a π-type filter circuit to suppress the conducted noise of the product. Capacitor CX62 is a safety capacitor to suppress differential mode interference. Resistors R62, R63, and R64 are bleeder resistors to prevent the product from being charged after power failure. Inductor L63 is a common-mode inductor to suppress common-mode interference. BR61 is a bridge rectifier that can rectify and prevent reverse connection. Capacitor CE61 is used for energy storage.

[0113] See also Fig.11 In a specific implementation, the circuit with VB as input and +12V as output is the first step-down circuit. Diode D71 is used to prevent current backflow. Inductor L71, resistor R71, resistor R72 and resistor R73 form LR filtering, which is used to suppress circuit interference. Capacitor CE71 is used for energy storage, and U71 is a power chip. Resistors R74 and R75 are used for output current detection to prevent the power chip U71 from short circuiting. Resistors R76 and R77 can adjust the output voltage. Capacitor C72 and inductor L72 are used for energy storage. Diode D72 and diode D73 are freewheeling diodes of inductor L72, capacitor CE72 is used for energy storage, and capacitor C73 is used for filtering. Resistor R78 is used as a dummy load to protect the power supply and improve the output stability and reliability. Diode D74 is a TVS tube to prevent overvoltage. Inductor L73 is a magnetic bead used to filter out high-frequency interference.

[0114] See also Fig.12In a specific implementation, in the second step-down circuit 320, capacitors C81 and C82 are input and output capacitors for improving output stability. Capacitor C83 is used for output filtering. Resistor R81 is a load resistor.

[0115] See also Fig.13 In a specific implementation, in the driving circuit 330, the capacitor C91 and the capacitor C92 are filter capacitors, which can enhance the ability of the driving signal output by the single chip microcomputer.

[0116] It should be noted that the circuit connection structure in the above specific embodiment is only an example, and the circuit can be configured according to requirements in actual applications.

[0117] The present application also provides a contactor detection method, which is applied to the control module 400 in the contactor detection system provided by one or more of the above embodiments. Fig.14 , Fig.14 This is a flow chart of a contactor detection method provided in an embodiment of the present application. The detection method may include steps 1401-1404, which are described in detail below.

[0118] Step 1401: Acquire a first sampling signal obtained by sampling a power signal of a contactor and a second sampling signal obtained by sampling a coil signal of a contactor at a set sampling frequency.

[0119] Step 1402: Determine the first time when the contactor starts to close according to the first sampling signal.

[0120] Step 1403: After the first time, determine a second time when the contactor completes the pull-in according to second sampling signals collected at three adjacent sampling times.

[0121] Step 1404: Determine the contactor's contacting time according to the first time and the second time.

[0122] In the embodiment of the present application, the set sampling frequency refers to the fixed interval time for regularly sampling the power signal and coil signal of the contactor. For example, the sampling frequency can be set to be sampled once every 156 μs. In one example, the ADC can be triggered to sample according to the set sampling frequency by a timer.

[0123] After each sampling is completed, it can be determined whether the first sampling signal is the first time when the contactor starts to close based on the first sampling signal corresponding to the power signal. In one example, when the first sampling signal is greater than the set closing threshold, it indicates that the contactor starts to close. At this time, the current sampling time of the first sampling signal can be determined as the first time T1 when the contactor starts to close.

[0124] See also Fig.15 , Fig.15 Schematic diagram of a sampling signal provided in an embodiment of the present application. Fig.15 In the example, there are three sampling signals, namely, the first sampling signal CH1, the second sampling signal CH2 and the contact signal CH3 of the contactor. Fig.16 As shown, due to the periodic change of the pull-in current and the working principle of the contactor, the waveform of CH2 includes two maximum values ​​and one minimum value. Among them, the first maximum value is the peak current, that is, the instantaneous peak value of the pull-in current in the initial stage. When the contactor is activated, the current increases rapidly to the maximum value to ensure that the contacts of the contactor are reliably pulled in. The second maximum value is the holding current, which is the stable value of the pull-in current when the contactor is in the holding state. The minimum value is the lowest point of the change of the pull-in current in the holding state, and this lowest point can be used as the second time T2 for the contactor to complete the pull-in.

[0125] Therefore, the embodiment of the present application can determine whether the second sampling signal of the three adjacent sampling times includes the second time T2 of completing the pull-in by determining whether the three adjacent sampling times conform to the above-mentioned change rule of the CH2 waveform. After obtaining the first time T1 and the second time T2, the pull-in time of the contactor can be determined based on the first time T1 and the second time T2.

[0126] In the embodiment of the present application, the three adjacent sampling times may include the first sampling time T21, the second sampling time T22, and the third sampling time T23. The first sampling time T21 is earlier than the second sampling time T22, and the second sampling time T22 is earlier than the third sampling time T23. If the three adjacent sampling times include the second time T2, it is necessary to satisfy that the second sampling signal of the first sampling time T21 is greater than the second sampling signal of the second sampling time T22, and the second sampling signal of the second sampling time T22 is greater than the second sampling signal of the third sampling time T23.

[0127] In order to reduce misjudgment caused by interference, the embodiment of the present application sets that the difference between the second sampling signal at the first sampling time T21 and the second sampling signal at the second sampling time T22 must be greater than the first threshold, and the difference between the second sampling signal at the second sampling time T22 and the second sampling signal at the third sampling time T23 must be greater than the second threshold. Among them, the first threshold and the second threshold can be equal or unequal, and there is no limitation again. In this way, when it is detected that the difference between the second sampling signal at the first sampling time and the second sampling signal at the second sampling time is greater than the first threshold, and the difference between the second sampling signal at the second sampling time and the second sampling signal at the third sampling time is greater than the second threshold, the second sampling time can be determined as the second time.

[0128] In the embodiment of the present application, the control module 400 may include an ADC to convert the first sampling signal and the second sampling signal from analog signals to digital signals. In order to improve transmission efficiency and performance, the first sampling signal and the second sampling signal output by the ADC may also be transferred by direct memory access (DMA).

[0129] Specifically, the ADC can be triggered by the timer to collect the first sampling signal and the second sampling signal according to the set sampling time. Then, the first sampling signal and the second sampling signal are transferred by DMA. When a set transfer cycle is completed, the data transfer interrupt is triggered, and the interrupt completion flag of the DMA is set to the first set value. For example, the set transfer cycle can be set to sample 32 points of the first sampling signal and the second sampling signal respectively each time. When the DAM completes the data transfer of 64 points, it marks the completion of the transfer cycle, triggers the DAM transmission completion interrupt, and sets the DAM interrupt completion flag to the first set value, for example, it can be set to 1.

[0130] When it is detected that the interrupt completion flag is the first set value, the interrupt completion flag is set to the second set value, for example, the second set value can be set to 0. It means that the last handling cycle has ended and a new handling cycle is ready to start. At the same time, it is necessary to record the values ​​of the first sampling signal and the second sampling signal collected in the last handling cycle. The first sampling signal and the second sampling signal are processed by the single chip microcomputer to obtain the contactor's pull-in time.

[0131] Fig.16 A flowchart of a data transfer method provided in a specific embodiment of the present application is shown. Fig.17 This is a flow chart of a method for detecting the contactor closing time provided in a specific embodiment of the present application. Fig.16 and Fig.17 .

[0132] In a specific embodiment, the single-chip microcomputer first configures ADC sampling, with a total of two channels ADC_channel1 and ADC_channel2, corresponding to the first sampling signal Vs signal and the second sampling signal Vi signal respectively. In this design, the ADC sampling is triggered by the timer once every 156μs, sampling 32 points, and after each conversion is completed, the DMA moves the converted data to the array. After completing the data transfer of 64 points in total for the two channels, the DMA triggers a DMA transfer completion interrupt, and the completion flag is set to 1 in the interrupt processing function.

[0133] Check whether the interrupt completion flag is 1 in the cycle. If it is 1, calculate the Vs and Vi values. When Vs> the pull-in threshold Ve, record the first time T1 when the pull-in starts. Vi2 is the pull-in current of the previous two times, Vi1 is the pull-in current of the previous time, Vi is the current pull-in current, and the initial values ​​of Vi2, Vi1, and Vi are 0. When (Vi2-Vi1>a) and (Vi1–Vi<-a), record the second time of the pull-in time as T2, and calculate T2–T1 as the pull-in time of the contactor. Store the pull-in current, then set Vi2=Vi1, Vi1=Vi, and start the calculation of the next cycle.

[0134] After capturing the pull-in waveforms for many times, it is found that the time corresponding to Vi2 is the moment when the contactor pulls in, and the pull-in current will reach the minimum value at this time. Therefore, as long as the time corresponding to the minimum pull-in current is confirmed, it can be considered that this time is the second time T2 when the contactor completes the pull-in.

[0135] The above are only preferred embodiments of the present application, and are not intended to limit the present application in any form. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments with equivalent changes without departing from the scope of the technical solution of the present application. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still fall within the scope of the technical solution of the present application.

Claims

1. A contactor detection system, characterized in that: The detection system includes an input module, a first sampling module, a second sampling module and a control module, wherein: The first sampling module and the second sampling module are electrically connected to the input module respectively, the first sampling module is used to collect a first sampling signal corresponding to the power signal output by the input module, and the second sampling module is used to collect a second sampling signal corresponding to the coil signal of the contactor; The control module is electrically connected to the first sampling module and the second sampling module to receive the first sampling signal and the second sampling signal of the first sampling module and the second sampling module, and detect the contactor's contacting time based on the first sampling signal and the second sampling signal.

2. The detection system according to claim 1, characterized in that: The control module is used for: Sampling the first sampling signal and the second sampling signal according to a set sampling frequency; Determine a first time when the contactor starts to close according to the first sampling signal; After the first time, determining a second time when the contactor completes the pull-in according to second sampling signals collected at three adjacent sampling times; The contactor's closing time is determined according to the first time and the second time.

3. The detection system according to claim 2, characterized in that: The three adjacent sampling times include a first sampling time, a second sampling time and a third sampling time, the first sampling time is earlier than the second sampling time, and the second sampling time is earlier than the third sampling time; in: When the first sampling signal is greater than a set pull-in threshold, determining the current sampling time of the first sampling signal as the first time when the contactor starts to pull in; When the difference between the second sampling signal at the first sampling time and the second sampling signal at the second sampling time is greater than a first threshold, and the difference between the second sampling signal at the second sampling time and the second sampling signal at the third sampling time is greater than a second threshold, the control module determines the second sampling time as the second time.

4. The detection system according to claim 1, characterized in that: The first sampling module includes a first sampling circuit, and the first sampling circuit is connected between the input module and the control module.

5. The detection system according to claim 4, characterized in that: The first sampling circuit is a voltage divider sampling circuit, and the first sampling circuit includes a first operational amplifier and a voltage divider subcircuit connected to the input module; The first operational amplifier includes a non-inverting input terminal connected to the output terminal of the voltage divider sub-circuit, an inverting input terminal connected to the ground, and an output terminal connected to the control module.

6. The detection system according to claim 4, characterized in that: The first sampling circuit is an amplifier sampling circuit, and the first sampling circuit includes a first operational amplifier; The first operational amplifier includes a non-inverting input terminal connected to the input module, an inverting input terminal connected to the ground, and an output terminal connected to the control module.

7. The detection system according to claim 1, characterized in that: The second sampling module includes a first buck circuit, a second buck circuit, a drive circuit, a coil circuit and a second sampling circuit; The first step-down circuit is connected between the input module and the driving circuit, the driving circuit is connected to the coil circuit, the coil circuit is connected to the second sampling circuit, the second sampling circuit is connected to the control module, and the control module is connected to the driving circuit; The second step-down circuit is connected between the first step-down circuit and the control module.

8. The detection system according to claim 7, characterized in that: The second sampling circuit is a low-side shunt sampling circuit, the coil circuit includes a coil and a sampling resistor, and the second sampling circuit includes a second operational amplifier; The first end of the coil is connected to the driving circuit, the second end of the coil is connected to the first end of the sampling resistor, and the second end of the sampling resistor is grounded; The second operational amplifier includes a non-inverting input terminal connected to the second end of the coil, an inverting input terminal connected to the ground, and an output terminal connected to the control module.

9. The detection system according to claim 7, characterized in that: The second sampling circuit is a high-side shunt sampling circuit, the coil circuit includes a coil and a sampling resistor, and the second sampling circuit includes a second operational amplifier; The first end of the sampling resistor is connected to the driving circuit, the second end of the sampling resistor is connected to the first end of the coil, and the second end of the coil is grounded; The second operational amplifier includes a non-inverting input terminal connected to the first terminal of the sampling resistor, an inverting input terminal connected to the second terminal of the sampling resistor, and an output terminal connected to the control module.

10. The detection system according to claim 1, characterized in that: The control module includes a single-chip microcomputer and an analog-to-digital converter. The first end of the analog-to-digital converter is connected to the first sampling module and the second sampling module, and the second end of the analog-to-digital converter is connected to the single-chip microcomputer.

11. The detection system according to claim 10, characterized in that: The control module is used for: Triggering the analog-to-digital converter to collect the first sampling signal and the second sampling signal according to a set sampling time; Performing data transfer on the first sampling signal and the second sampling signal through direct memory access, wherein when a set transfer cycle is completed, the data transfer interrupt is triggered, and the interrupt completion flag of the direct memory access is set to a first set value; When it is detected that the interrupt completion flag is a first set value, the interrupt completion flag is set to a second set value, and the values ​​of the first sampling signal and the second sampling signal are recorded.

12. A contactor detection method, characterized in that: The test method includes: Acquire a first sampling signal obtained by sampling a power supply signal of the contactor and a second sampling signal obtained by sampling a coil signal of the contactor according to a set sampling frequency; Determine a first time when the contactor starts to close according to the first sampling signal; After the first time, determining a second time when the contactor completes the pull-in according to second sampling signals collected at three adjacent sampling times; The contactor's closing time is determined according to the first time and the second time.

13. The detection method according to claim 12, characterized in that: The three adjacent sampling times include a first sampling time, a second sampling time and a third sampling time, the first sampling time is earlier than the second sampling time, and the second sampling time is earlier than the third sampling time; The step of determining the first time when the contactor starts to close according to the first sampling signal includes: When the first sampling signal is greater than a set pull-in threshold, determining the current sampling time of the first sampling signal as the first time when the contactor starts to pull in; After the first time, determining the second time when the contactor completes the pull-in according to the second sampling signals collected at three adjacent sampling times includes: When the difference between the second sampling signal at the first sampling time and the second sampling signal at the second sampling time is greater than a first threshold, and the difference between the second sampling signal at the second sampling time and the second sampling signal at the third sampling time is greater than a second threshold, the second sampling time is determined as the second time.

14. The detection method according to claim 12, characterized in that: The method of acquiring a first sampling signal obtained by sampling a power supply signal of the contactor and a second sampling signal obtained by sampling a coil signal of the contactor at a set sampling frequency includes: Triggering the analog-to-digital converter to collect the first sampling signal and the second sampling signal according to the set sampling time; Data transfer is performed on the first sampling signal and the second sampling signal by direct memory access, wherein when a set transfer cycle is completed, the data transfer interrupt is triggered, and the interrupt completion flag of the direct memory access is set to a first set value; When it is detected that the interrupt completion flag is a first set value, the interrupt completion flag is set to a second set value, and the values ​​of the first sampling signal and the second sampling signal are recorded.

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