Contactor detection system

Abstract

The utility model discloses a detection system 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 for a contactor. Background Art

[0002] During actual operation, the time difference between the moment the control power supply is applied to an electronic contactor and the moment the contactor's contacts close and the main circuit is turned on is typically referred to as the contactor's pull-in time. Measuring the contactor's pull-in time can be used to determine the operating status of the device. Regularly monitoring the contactor's pull-in time can help identify potential faults and other issues.

[0003] Typically, laboratory measurements of contactor release time involve manual stopwatches, oscilloscopes, and specialized measuring instruments. In industry, the closing time of the contactor's auxiliary contacts is often used to equate the main contact's pull-in time. However, this approach presents two problems. First, it increases the cost of the auxiliary contacts and cables. Second, while the main circuit operates at high voltage and high current, the auxiliary contact's signal operates at low voltage and low current. This presents a risk of voltage breakdown in actual operation. Third, the auxiliary contacts operate at low current, and after prolonged use, their impedance may increase and prevent them from closing. Utility Model Content

[0004] The purpose of this application is to provide a contactor detection system to solve the problems of high cost and low safety of contactor detection in the prior art.

[0005] To achieve the above objectives, an embodiment of the present application provides a contactor detection system, the detection system including 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 from the first sampling module and the second sampling signal, and detects the contactor's contacting 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 at a set sampling frequency;

[0010] Determining a 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 closing 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 an 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.

[0014] 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 sub-circuit connected to the input module;

[0015] 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.

[0016] 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;

[0017] 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.

[0018] 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;

[0019] 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;

[0020] The second step-down circuit is connected between the first step-down circuit and the control module.

[0021] 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;

[0022] 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;

[0023] 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.

[0024] 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;

[0025] 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;

[0026] 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.

[0027] 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.

[0028] In the embodiment of the present application, the control module is used to:

[0029] Triggering the analog-to-digital converter to collect the first sampling signal and the second sampling signal according to the set sampling time;

[0030] 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;

[0031] 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.

[0032] 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 closing time of the contactor 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 closing time of the contactor 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 low-voltage and low-current auxiliary contacts, the risk of high- and low-voltage breakdown in the detection system is reduced, and the safety of contactor detection is improved.

[0033] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. 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.

[0035] Figure 1 This is a schematic structural diagram of a contactor detection system provided in one embodiment of the present application;

[0036] Figure 2 This is a structural schematic diagram of a contactor detection system provided in another embodiment of the present application;

[0037] Figure 3 This is a schematic structural diagram of a voltage divider sampling circuit provided in an embodiment of the present application;

[0038] Figure 4 This is a schematic structural diagram of an amplifier sampling circuit provided in an embodiment of the present application;

[0039] Figure 5 Schematic diagram of the structure of a low-side current shunt sampling circuit provided in an embodiment of the present application;

[0040] Figure 6 This is a structural diagram of a high-side current shunt sampling circuit provided in an embodiment of the present application;

[0041] Figure 7 This is a schematic structural diagram of a voltage divider sampling circuit provided in a specific embodiment of the present application;

[0042] Figure 8 This is a structural diagram of a low-side current shunt sampling circuit provided in a specific embodiment of the present application;

[0043] Figure 9 This is a schematic structural diagram of a coil circuit provided in a specific embodiment of the present application;

[0044] Figure 10 This is a schematic structural diagram of a circuit in an input module provided in a specific embodiment of the present application;

[0045] Figure 11 This is a structural diagram of a first step-down circuit provided in a specific embodiment of the present application;

[0046] Figure 12 This is a structural diagram of a second step-down circuit provided in a specific embodiment of the present application;

[0047] Figure 13 This is a schematic structural diagram of a driving circuit provided in a specific embodiment of the present application;

[0048] Figure 14 A schematic flow chart of a contactor detection method provided in an embodiment of the present application;

[0049] Figure 15 A schematic diagram of a sampling signal provided in an embodiment of the present application.

[0050] Figure 16 A flowchart of a data transfer method provided in a specific embodiment of the present application is shown;

[0051] Figure 17 The figure is a flow chart of a method for detecting the contactor closing time provided in a specific embodiment of the present application. DETAILED DESCRIPTION

[0052] The embodiments of the present application are described in detail below. 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 are not to be construed as limiting the present application.

[0053] 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, not 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 efforts are within the scope of protection of this application.

[0054] In the embodiments of the present application, it should be noted that, in this document, 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.

[0055] Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not explicitly listed or inherent to such article or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the article or device comprising the element.

[0056] In the description of the embodiments of this application, words such as "example" or "for example" are used to indicate an example, illustration, or description. Any embodiment or design described as "for example" or "for example" in the embodiments of this application is not to be construed as being preferred or having more advantages than another embodiment or design. The use of words such as "example" or "for example" is intended to clearly present relative concepts.

[0057] In addition, in the embodiments of the present application, "plurality" refers to two or more. 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 does not limit which ones are included. For example, "including at least one of A, B, and C" means including A, B, C, A and B, A and C, B and C, or A, B, and C.

[0058] 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.

[0059] The first electrode / first end of each transistor used in the embodiments of the present application is one of the source and the drain, and the second electrode / 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 can be structurally indistinguishable, that is, the first electrode / first end and the second electrode / second end of the transistor in the embodiments of the present application can be structurally indistinguishable. For example, in the case where the transistor is a P-type transistor, the first electrode / first end of the transistor is the source, and the second electrode / second end is the drain; for example, in the case where the transistor is an N-type transistor, the first electrode / first end of the transistor is the drain, and the second electrode / second end is the source.

[0060] 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 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.

[0061] An embodiment of the present application provides a contactor detection system, which is described in detail below.

[0062] See also Figure 1 , Figure 1FIG1 is a schematic diagram of the structure of a contactor detection system provided in one 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 each electrically connected to the input module 100. The control module 400 is electrically connected to the first sampling module 200 and the second sampling module 300.

[0063] 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, etc.

[0064] The input voltage is input to the first sampling module 200 and the second sampling module 300. 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.

[0065] The control module 400 can receive a first sampling signal corresponding to the power signal, collected by the first sampling module 200. When the first sampling signal is greater than a set pull-in threshold, it indicates that the contactor has begun to close. The set pull-in threshold refers to the threshold at which the contactor begins to close, and this set pull-in threshold can be determined based on the contactor manufacturer's design requirements and application needs. Therefore, the first time when the contactor begins to close can be obtained from the first sampling signal. This first time is the start time of contactor closing.

[0066] The control module 400 can also receive a second sampling signal corresponding to the contactor's coil signal, collected by the second sampling module 300. When the coil signal is applied to the contactor's coil, the coil generates a magnetic field, causing the contactor's main contacts to close or open. The coil signal can reflect the contactor's state. Therefore, the second sampling signal can be used to determine the second time the contactor completes engagement, which is the end time of the contactor's engagement.

[0067] As can be seen from the above, the control module 400 can obtain a first time indicating the start of contactor closure and a second time indicating the completion of contactor closure based on the first sampling signal and the second sampling signal. Therefore, the control module 400 can obtain the contactor closure time based on the first time corresponding to the first sampling signal and the second time corresponding to the second sampling signal.

[0068] The contactor detection system 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 need to add the connection of low-voltage and low-current auxiliary contacts, the risk of high- and low-voltage breakdown in the detection system is reduced, and the safety of contactor detection is improved.

[0069] Next, continue to Figure 1 Each module shown and the specific implementation methods that may be used in actual applications are described in detail.

[0070] See also Figure 2 In some embodiments of the present application, the first sampling module 200 may include a first sampling circuit 210, which 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.

[0071] The second sampling module 300 may include a first step-down circuit 310, a second step-down circuit 320, a drive circuit 330, a coil circuit 340, and a second sampling circuit 350. The first step-down 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 step-down circuit 320 is connected between the first step-down circuit 310 and the control module 400.

[0072] The first step-down circuit 310 can step down the power signal input to the module 100 and then input it to the second step-down circuit 320 and the drive circuit 330. The second step-down circuit 320 is used to power the control module 400. The drive circuit 330 is used to provide a drive signal to the coil circuit 340 of the contactor, causing the main contacts of the contactor to close or open. After the second sampling circuit 350 obtains the coil signal from the coil circuit 340, it can output a second sampling signal to the control module 400.

[0073] In the embodiment of the present application, the first sampling circuit 210 may include, but is not limited to, a voltage divider sampling circuit or an amplifier sampling circuit. A voltage divider sampling circuit divides the coil signal into a lower voltage before signal acquisition to meet subsequent circuit requirements. An amplifier sampling circuit amplifies the input signal amplitude before signal acquisition to increase the coil signal strength or enhance the signal-to-noise ratio.

[0074] Both the voltage divider sampling circuit and the amplifier sampling circuit 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 pre-circuit for receiving the coil signal and has a high input impedance. The inverting input terminal is usually connected to the output terminal of the operational amplifier for receiving 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 amplification function and have stability. The output terminal is used to provide an amplified signal, which is usually proportional to the input signal. The output terminal generally has a low output impedance so that it can drive subsequent circuits.

[0075] The following describes in detail the voltage divider sampling circuit and the amplifier sampling circuit as examples.

[0076] See also Figure 3 , Figure 3 This is a schematic diagram of the structure of a voltage divider sampling circuit provided in an embodiment of the present application. In this embodiment of the present application, the first sampling circuit 210 can be a voltage divider sampling circuit. The first sampling circuit 210 can include a first operational amplifier A1 and a voltage divider sub-circuit connected to the input module 100. The voltage divider sub-circuit is a circuit for dividing the voltage of the power supply signal, typically 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.

[0077] 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 ground, and an output terminal c1 connected to the control module 400. The voltage divider subcircuit divides the power supply signal, reducing the power supply signal to a range suitable for the operating 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 via a feedback circuit, so that the first operational amplifier A1 forms negative feedback. R11 and R12 are used to low-pass filter the input signal of the voltage divider subcircuit, and R14 and C11 are used to low-pass filter the output signal of the first operational amplifier A1. R13 serves as the feedback resistor of the first operational amplifier A1 and is arranged between the output terminal c1 and the inverting input terminal b1. The first operational amplifier A1 adjusts the output signal based on the magnitude 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 achieving 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 .

[0078] See also Figure 4 , Figure 4 FIG2 is a schematic diagram of the structure of an amplifier sampling circuit provided in an embodiment of the present application. In this embodiment of the present application, the first sampling circuit 210 can also be an amplifier sampling circuit, and the first sampling circuit 210 can include a first operational amplifier A1. The first operational amplifier A1 can include a non-inverting input terminal a1 connected to the input module 100, an inverting input terminal b1 connected to ground, and an output terminal c1 connected to the control module 400.

[0079] 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 via a feedback circuit, so that the first operational amplifier A1 forms negative feedback. R11 and R12 are used to low-pass filter the power signal of the input module, and R14 and C11 are used to low-pass filter the output signal of the first operational amplifier A1. R13 serves as the feedback resistor of the first operational amplifier A1 and is arranged between the output terminal c1 and the inverting input terminal b1. The first operational amplifier A1 adjusts the output signal based on the magnitude and polarity of the feedback signal so that the feedback signal is equal to or nearly equal to the power signal, thereby achieving 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.

[0080] 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 low-side shunt sampling circuits and high-side shunt sampling circuits. 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.

[0081] 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, the collected voltage signal can be amplified, regulated, and filtered.

[0082] The following describes in detail the low-side shunt sampling circuit and the high-side shunt sampling circuit as examples.

[0083] See also Figure 5 , Figure 5 Schematic diagram of a low-side current shunt sampling circuit provided in an embodiment of the present application. In this embodiment of the present application, the second sampling circuit 350 may be a low-side current 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.

[0084] The first end of coil L is connected to drive circuit 330, and the second end of coil L is connected to the first end of sampling resistor Rs. The second end of sampling resistor Rs is grounded. Sampling resistor Rs is connected between coil L and ground DGND, forming a shunt circuit. When current flows through coil L and sampling resistor Rs, sampling resistor Rs generates a voltage drop proportional to the current, which is the difference between V2 and V1.

[0085] 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 low-pass filter the input signal of the drive circuit, and R24 is a balancing resistor used to eliminate the impact of bias current on the output voltage. R23 serves as the feedback resistor of the second operational amplifier A2 and is arranged between the output terminal c2 and the inverting input terminal b2. The inverting input terminal b2 and the output terminal c2 are connected via a feedback circuit, so that the second operational amplifier A2 forms negative feedback. The output terminal c2 of the second operational amplifier A2 provides the amplified second sampling signal Vi to the control module 400.

[0086] See also Figure 6 , Figure 6 Schematic diagram of a high-side current shunt sampling circuit provided in an embodiment of the present application. In this embodiment of the present application, the second sampling circuit 350 may also be a high-side current 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.

[0087] The first end of the sampling resistor Rs is connected to the drive circuit 330, and the second end of the sampling resistor Rs is connected to the first end of the coil L. The second end of the coil L is grounded. The sampling resistor Rs is connected between the drive 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, i.e., the difference between V2 and V1.

[0088] 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 low-pass filter the input signal of the drive circuit, and R24 is a balancing resistor used to eliminate the impact of bias current on the output voltage. R23 serves as the 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 via a feedback circuit, so that the second operational amplifier A2 forms negative feedback. The output terminal c2 of the second operational amplifier A2 provides the amplified second sampling signal Vi to the control module 400.

[0089] In an 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 ADC 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 analog signals to digital signals through the ADC, and then the digital signals are input into the single-chip microcomputer, which then processes the digital signals to obtain the contactor's pull-in time.

[0090] The following is an example of a specific embodiment. Figure 2 Describe each module in.

[0091] See also Figure 7 , taking the voltage divider sampling circuit as an example for the first sampling circuit 210. In a specific implementation, in this 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 used to prevent overvoltage and negative pressure. R36 and R37 form a low-pass filter. A1, R38, R39, and C32 are the signal conditioning subcircuit. R39 and C33 form a low-pass filter. Finally, the first sampling signal Vs is output and enters the control module 400.

[0092] See also Figure 8 Taking the low-side shunt sampling circuit as an example, the second sampling circuit 350 includes a second operational amplifier A2 and a third operational amplifier A3. This implementation adds an active filtering circuit including the third operational amplifier A3 to the aforementioned second sampling circuit to eliminate noise from the second sampling circuit. Active filtering of the output signal of the second operational amplifier A2 produces a more accurate second sampling signal Vi.

[0093] See also Figure 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.

[0094] See also Figure 10In one specific implementation, the input voltage section, with terminal J61 as input and VB as output, represents the electromagnetic compatibility (EMC) circuit. Variable resistor RV61 and resistor R61 form the EMS circuit to prevent external high-voltage interference that could damage the product. Inductor L61, capacitor CX61, capacitor CX62, and inductor L62 form a π-type filter circuit to suppress the product's conducted noise. Capacitor CX62 is a safety capacitor that suppresses differential-mode interference. Resistors R62, R63, and R64 act as bleed resistors to prevent the product from becoming energized after a power outage. Inductor L63 is a common-mode inductor that suppresses common-mode interference. BR61 is a bridge rectifier that provides rectification and reverse polarity protection. Capacitor CE61 is used for energy storage.

[0095] See also Figure 11 In one 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 an LR filter to suppress circuit interference. Capacitor CE71 is used for energy storage, and U71 is a power supply chip. Resistors R74 and R75 are used for output current detection to prevent power supply chip U71 from shorting. 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 for inductor L72, capacitor CE72 is used for energy storage, and capacitor C73 is used for filtering. Resistor R78 acts as a dummy load to protect the power supply and improve output stability and reliability. Diode D74 is a TVS diode to prevent overvoltage. Inductor L73 is a ferrite bead used to filter out high-frequency interference.

[0096] See also Figure 12 In one specific implementation, in the second step-down circuit 320, capacitors C81 and C82 are input and output capacitors used to improve output stability. Capacitor C83 is used for output filtering. Resistor R81 is a load resistor.

[0097] See also Figure 13 In a specific implementation, in the driving circuit 330, the capacitor C91 and the capacitor C92 are filter capacitors that can enhance the ability of the driving signal output by the single chip microcomputer.

[0098] 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 actual needs in actual applications.

[0099] 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. Figure 14 , Figure 14This 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.

[0100] 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 the contactor at a set sampling frequency.

[0101] Step 1402: Determine the first time when the contactor starts to close according to the first sampling signal.

[0102] Step 1403: After the first time, determine the second time when the contactor completes the pull-in according to the second sampling signals collected at three adjacent sampling times.

[0103] Step 1404: Determine the contactor's closing time according to the first time and the second time.

[0104] In the embodiments of the present application, the set sampling frequency refers to a fixed interval at which the power signal and coil signal of the contactor are regularly sampled. For example, the set sampling frequency can be set to be once every 156 μs. In one example, a timer can be used to trigger an ADC to perform sampling according to the set sampling frequency.

[0105] After each sampling is completed, a determination can be made based on the first sampling signal corresponding to the power signal whether the first sampling signal represents the first time the contactor begins closing. In one example, when the first sampling signal is greater than a set closing threshold, it indicates that the contactor has begun closing. In this case, the current sampling time of the first sampling signal can be determined as the first time T1 at which the contactor begins closing.

[0106] See also Figure 15 , Figure 15 This is a schematic diagram of a sampling signal provided in an embodiment of the present application. Figure 15 There are three sampling signals, namely the first sampling signal CH1, the second sampling signal CH2 and the contact signal CH3 of the contactor. Figure 16 As shown in the figure, due to the cyclical variation of the pickup current and the operating principle of the contactor, the waveform of CH2 includes two maximum values ​​and one minimum value. The first maximum value is the peak current, which is the instantaneous peak value of the pickup current during the initial stage of the pickup. When the contactor is activated, the current rapidly increases to its maximum value to ensure reliable closing of the contactor contacts. The second maximum value is the holding current, which is the stable value of the pickup current when the contactor is in the holding state. The minimum value is the lowest point of the pickup current in the holding state. This lowest point can be used as the second time T2 for the contactor to complete the pull-in.

[0107] Therefore, the embodiment of the present application can determine whether the second sampling signal of the three adjacent sampling times contains the second time T2 for completing the contactor by determining whether the three adjacent sampling times conform to the above-mentioned change pattern of the CH2 waveform. After obtaining the first time T1 and the second time T2, the contactor's contactor closing time can be determined based on the first time T1 and the second time T2.

[0108] In the embodiment of the present application, the three adjacent sampling times may include a first sampling time T21, a second sampling time T22, and a 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 sampling time T2, it is necessary to satisfy the following conditions: the second sampling signal at the first sampling time T21 is greater than the second sampling signal at the second sampling time T22, and the second sampling signal at the second sampling time T22 is greater than the second sampling signal at the third sampling time T23.

[0109] In order to reduce misjudgments caused by interference, the embodiment of the present application sets the difference between the second sampling signal at the first sampling time T21 and the second sampling signal at the second sampling time T22 to be greater than a 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 to be greater than a second threshold. The first threshold and the second threshold may be equal or unequal, again without limitation. Thus, 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 may be determined as the second time.

[0110] 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. To improve transmission efficiency and performance, the first sampling signal and the second sampling signal output by the ADC may be transferred via direct memory access (DMA).

[0111] 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 DMA interrupt completion flag 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.

[0112] When the interrupt completion flag is detected to be at the first set value, the interrupt completion flag is set to a second set value, for example, 0. This indicates that the previous transport cycle has ended and a new transport cycle is about to begin. Simultaneously, the values ​​of the first and second sampling signals collected during the previous transport cycle are recorded. The microcontroller processes the first and second sampling signals to determine the contactor's closing time.

[0113] Figure 16 The figure is a flowchart of a data transfer method provided in a specific embodiment of the present application. Figure 17 This is a flow chart of a method for detecting the contactor closing time provided in a specific embodiment of the present application. Figure 16 and Figure 17 .

[0114] In one specific embodiment, the microcontroller first configures ADC sampling, with two channels, ADC_channel1 and ADC_channel2, corresponding to the first sampling signal, Vs, and the second sampling signal, Vi, respectively. This design uses a timer to trigger ADC sampling every 156 μs, sampling 32 points. After each conversion, the DMA transfers the converted data to an array. After the DMA completes the transfer of 64 points across the two channels, it triggers a DMA transfer complete interrupt, setting the completion flag to 1 in the interrupt handler.

[0115] The loop checks whether the interrupt completion flag is 1. If it is, calculate the Vs and Vi values. When Vs > the pull-in threshold Ve, record the first time T1 when the pull-in begins. Vi2 is the pull-in current of the previous two times, Vi1 is the previous pull-in current, and Vi is the current pull-in current. The initial values ​​of Vi2, Vi1, and Vi are 0. When (Vi2-Vi1>a) and (Vi1-Vi<-a), record the second time T2 when the pull-in time is completed. Calculate T2-T1 to obtain the pull-in time of the contactor. Store the pull-in current, then set Vi2=Vi1 and Vi1=Vi to begin the calculation of the next cycle.

[0116] By capturing the pull-in waveform multiple times, we found that the time corresponding to Vi2 is the moment the contactor pulls in, at which time the pull-in current reaches its minimum value. Therefore, as long as the time corresponding to the minimum pull-in current value is determined, it can be considered as the second time T2 when the contactor completes pull-in.

[0117] The above are merely preferred embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make slight changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present application. However, any simple modifications, equivalent changes and modifications 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 are still 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 from the first sampling module and the second sampling module, and detects 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 at a set sampling frequency; determining 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 closing 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 1, characterized in that The first sampling module includes a first sampling circuit connected between the input module and the control module.

4. The detection system according to claim 3, 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 sub-circuit 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.

5. The detection system according to claim 3, 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.

6. 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.

7. The detection system according to claim 6, 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.

8. The detection system according to claim 6, 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.

9. The detection system according to claim 1, characterized in that: 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.

10. The detection system according to claim 9, 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, triggering the data transfer interrupt, and setting the interrupt completion flag of the direct memory access to a first set value; When it is detected that the interruption completion flag is a first set value, the interruption completion flag is set to a second set value, and the values ​​of the first sampling signal and the second sampling signal are recorded.

Images