Contactor monitoring device and contactor

Abstract

The utility model provides a contactor monitoring device and a contactor, and belongs to the technical field of contactor monitoring, and the contactor monitoring device comprises a first signal processing circuit, a second signal processing circuit and a controller. Wherein the first signal processing circuit is connected with the first power tube and is used for generating a first voltage difference value according to potentials at two ends of the first power tube; the second signal processing circuit is connected with the second power tube and is used for generating a second voltage difference value according to the potentials at the two ends of the second power tube; the controller is connected with the first signal processing circuit and the second signal processing circuit and used for generating a monitoring result according to the first voltage difference value and the second voltage difference value. Therefore, the short circuit phenomenon can be timely captured at the early stage of the first power tube and the second power tube, so that the temperature rise caused by long-time short circuit grounding of the coil is avoided, and the effect of accurately monitoring the early stage of short circuit of the coil loop is realized.

Description

Technical Field

[0001] The present application relates to the technical field of contactor monitoring, and in particular to a contactor monitoring device and a contactor. Background Art

[0002] As a key device in the power control field, the stability and reliability of contactor performance are crucial to the operation of the entire power system. Contactors primarily consist of components such as a circuit board, coil, and iron core. The power transistor on the circuit board forms a series circuit with the coil. By controlling the power transistor, the coil circuit is energized, generating a magnetic field that closes the contacts and achieves power control.

[0003] While connecting the coil and power transistor in series allows for rapid control of the coil circuit's on / off state, the power transistor can experience thermal breakdown during prolonged on / off operation, potentially shorting the coil circuit to ground. This can cause a continuous temperature rise, ultimately leading to burnout of the power transistor and coil, and overall system failure. However, the temperature rise caused by a power transistor short circuit takes time to resolve. During the initial phase of a power transistor short circuit, the contactor can maintain normal operation for a period of time. Prompt repair of the contactor during this period can avoid potential safety hazards caused by contactor burnout. Therefore, detecting a coil circuit short circuit in its early stages is a pressing issue. Utility Model Content

[0004] In view of the deficiencies in the prior art, the present application provides a contactor monitoring device and a contactor.

[0005] In a first aspect, the present application provides a contactor monitoring device, comprising:

[0006] a first signal processing circuit connected to the first power tube, and configured to generate a first voltage difference according to the potentials at both ends of the first power tube;

[0007] a second signal processing circuit connected to the second power tube and configured to generate a second voltage difference according to the potentials at both ends of the second power tube; wherein the first power tube, the second power tube, and the coil in the contactor are connected in series;

[0008] A controller is connected to the first signal processing circuit and the second signal processing circuit, and is used to generate a monitoring result according to the first voltage difference and the second voltage difference.

[0009] Optionally, the first signal processing circuit includes a first isolation amplifier chip, a first subtraction subcircuit and a reference subcircuit;

[0010] The first isolation amplifier chip includes a first input terminal connected to the first power supply and the first electrode of the first power tube, a second input terminal connected to the second electrode of the first power tube, and a first output terminal and a second output terminal connected to the first subtraction sub-circuit;

[0011] The reference subcircuit is used to provide a reference voltage;

[0012] The first subtraction subcircuit includes a first input terminal connected to the first output terminal of the first isolation amplifier chip, a second input terminal connected to the second output terminal of the first isolation amplifier chip and the reference subcircuit, and an output terminal connected to the controller.

[0013] Optionally, the reference subcircuit includes a first resistor, a second resistor and a first operational amplifier;

[0014] The first resistor includes a first end connected to the second power supply and a second end connected to the second resistor and the first operational amplifier;

[0015] The second resistor includes a first end connected to the second end of the first resistor and the first operational amplifier and a second end connected to ground;

[0016] The first operational amplifier includes a first input terminal connected to the second end of the first resistor and the first end of the second resistor, a second input terminal connected to the first subtraction sub-circuit, and an output terminal.

[0017] Optionally, the second signal processing circuit includes a second isolation amplifier chip and a second subtraction sub-circuit;

[0018] The second isolation amplifier chip includes a first input terminal connected to the first electrode of the second power tube, a second input terminal connected to the second electrode of the second power tube and the ground, and a first output terminal and a second output terminal connected to the second subtraction sub-circuit;

[0019] The second subtraction sub-circuit includes a first input terminal connected to the first output terminal of the second isolation amplifier chip, a second input terminal connected to the second output terminal of the second isolation amplifier chip, and an output terminal connected to the controller.

[0020] Optionally, a first driving circuit is further included, which is connected to the control electrode of the first power tube and the controller, and is used to control the on and off of the first power tube according to the driving signal output by the controller.

[0021] Optionally, a second driving circuit is further included, connected to the control electrode of the second power tube and the controller, and is used to control the on and off of the second power tube according to the pulse width modulation signal output by the controller.

[0022] Optionally, the monitoring result includes a first monitoring result for characterizing a state of the first power tube and a second monitoring result for characterizing a state of the second power tube;

[0023] The controller includes a first monitoring unit and a second monitoring unit;

[0024] The first monitoring unit is configured to generate the first monitoring result according to the first voltage difference;

[0025] The second monitoring unit is configured to generate the second monitoring result according to the second voltage difference and the pulse width modulation signal.

[0026] Optionally, the controller further includes a drive signal generating unit;

[0027] The drive signal generating unit is used to generate a drive signal for a power-on test state and a pulse width drive signal when the contactor is powered on, so as to control the first power tube to be turned on and the second power tube to be turned off;

[0028] The first monitoring unit is further configured to generate a first monitoring result according to a first voltage difference between the first power tube being on and the second power tube being off;

[0029] The second monitoring unit is further configured to generate a second monitoring result according to a second voltage difference when the first power tube is turned on and the second power tube is turned off.

[0030] Optionally, a communication circuit is further included, which is connected to the controller and the host computer and is used to receive the monitoring results and send the monitoring results to the host computer.

[0031] In a second aspect, in one embodiment, the present application provides a contactor, including: the contactor monitoring device as described above.

[0032] Through the above technical solution, this application has at least the following beneficial technical effects:

[0033] First, the first signal processing circuit and the second signal processing circuit respectively collect the potentials across the first power tube and the second power tube to obtain a first voltage difference and a second voltage difference. The first voltage difference can directly reflect the state of the first power tube, while the second voltage value can directly reflect the state of the second power tube. Then, the controller analyzes the first voltage difference and the second voltage difference to obtain monitoring results for the first power tube and the second power tube. This allows the early stages of a short circuit in the first power tube and the second power tube to be detected promptly, thereby avoiding temperature increases caused by a prolonged short circuit to ground of the coil and achieving accurate monitoring of the early stages of a coil loop short circuit. 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 block diagram of a contactor monitoring device in one embodiment of the present application;

[0036] Figure 2 This is a circuit connection diagram of a contactor monitoring device in one embodiment of the present application;

[0037] Figure 3 This is a circuit connection diagram of a reference sub-circuit in one embodiment of the present application;

[0038] Figure 4 This is a block diagram of a contactor monitoring device in another embodiment of the present application.

[0039] Explanation of the accompanying drawings: 1. First signal processing circuit; 11. First subtraction subcircuit; 12. Reference subcircuit; 2. Second signal processing circuit; 21. Second subtraction subcircuit; 3. Controller; 31. First monitoring unit; 32. Second monitoring unit; 33. Drive signal generating unit; 4. First drive circuit; 5. Second drive circuit. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0041] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "plurality" means two or more, unless otherwise specifically qualified. In this application, the word "exemplary" is used to mean "serving as an example, illustration, or illustration." Any embodiment described in this application as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is provided to enable anyone skilled in the art to implement and use the present application. In the following description, details are listed for illustrative purposes. It should be understood that one of ordinary skill in the art will recognize that the present application can be implemented without these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0042] First, as Figure 1 As shown, in one embodiment, the present application provides a contactor monitoring device, which includes a first signal processing circuit 1, a second signal processing circuit 2, and a controller 3. The first signal processing circuit 1 is connected to the first power tube Q1 and is configured to generate a first voltage difference based on the potential across the first power tube Q1; the second signal processing circuit 2 is connected to the second power tube Q2 and is configured to generate a second voltage difference based on the potential across the second power tube Q2; the first power tube Q1, the second power tube Q2, and the coil in the contactor are connected in series; and the controller 3 is connected to the first signal processing circuit 1 and the second signal processing circuit 2 and is configured to generate a monitoring result based on the first voltage difference and the second voltage difference.

[0043] As an example, a coil circuit formed by connecting the first power transistor Q1, the second power transistor Q2 in series with the coil can be set on the high side, that is, connected in series between the positive terminal of the first power supply and one end of the coil, and the second power transistor Q2 can be set on the low side, that is, between the other end of the series coil and ground. When the contactor is operating normally, the first power transistor Q1 can remain normally open, allowing current to flow continuously. The second power transistor Q2, on the other hand, switches on and off with a certain duty cycle. By adjusting its on-time, the current flowing through the coil is controlled, thus achieving energy conservation while achieving contactor pull-in and pull-out.

[0044] The monitoring result includes a first monitoring result for characterizing the state of the first power tube Q1 and a second monitoring result for characterizing the state of the second power tube Q2.

[0045] For example, the first and second power transistors Q1 and Q2 typically need to withstand high voltages and high currents, making them more likely to fail in the coil loop. Furthermore, because the second power transistor Q2 must repeatedly turn on and off to regulate current, it experiences increased switching losses and thermal stress compared to the first power transistor Q1, accelerating aging of the second power transistor Q2. Therefore, by specifically monitoring the status of the first and second power transistors Q1 and Q2, which are more likely to fail in the coil loop, the coil loop status can be determined more promptly.

[0046] Combine Figure 2 The potentials across the first power transistor Q1 may include a first high-end potential UAX and a first low-end potential UAY. The first high-end potential UAX may be the potential on the input side of the first power transistor Q1, and the first low-end potential UAY may be the potential on the output side of the first power transistor Q1. The potentials across the second power transistor Q2 may include a second high-end potential UBX and a second low-end potential UBY. The second high-end potential UBX may be the potential on the input side of the second power transistor Q2, and the second low-end potential UBY may be the potential on the output side of the second power transistor Q2.

[0047] In the above embodiment, the first signal processing circuit 1 and the second signal processing circuit 2 are firstly used to respectively collect the potentials across the first power transistor Q1 and the second power transistor Q2 to obtain a first voltage difference and a second voltage difference. The first voltage difference can directly reflect the state of the first power transistor Q1, while the second voltage difference can directly reflect the state of the second power transistor Q2. The controller 3 then analyzes the first voltage difference and the second voltage difference to obtain monitoring results for the first power transistor Q1 and the second power transistor Q2. This allows the early stages of a short circuit in the first power transistor Q1 and the second power transistor Q2 to be detected promptly, thereby avoiding temperature rise caused by a prolonged short circuit to ground in the coil, and achieving the effect of accurately monitoring the early stages of a coil loop short circuit.

[0048] Reference Figure 2As an embodiment of the first signal processing circuit 1, the first signal processing circuit 1 includes a first isolation amplifier chip U1, a first subtraction sub-circuit 11, and a reference sub-circuit 12; wherein the first isolation amplifier chip U1 includes a first input terminal connected to the first power supply and the first electrode of the first power tube Q1, a second input terminal connected to the second electrode of the first power tube Q1, a first output terminal and a second output terminal connected to the first subtraction sub-circuit 11; the reference sub-circuit 12 is used to provide a reference voltage; the first subtraction sub-circuit 11 includes a first input terminal connected to the first output terminal of the first isolation amplifier chip U1, a second input terminal connected to the second output terminal of the first isolation amplifier chip U1 and the reference sub-circuit 12, and an output terminal connected to the controller 3.

[0049] In some embodiments, the first subtraction sub-circuit 11 may include a second operational amplifier U4 and a third resistor R3. The second operational amplifier U4 includes a first input terminal connected to the first end of the third resistor R3 and the first output terminal of the first isolation amplifier chip U1, a second input terminal connected to the reference sub-circuit 12 and the second output terminal of the first isolation amplifier chip U1, and an output terminal connected to the second end of the third resistor R3 and the controller 3. The first input terminal of the second operational amplifier U4 may be a non-inverting input terminal, and the second input terminal may be an inverting input terminal. The first isolation amplifier chip U1 is also connected to the high-voltage ground PGND and the low-voltage ground DGND, respectively.

[0050] As an example, the reference sub-circuit 12 is connected to the second input terminal of the second operational amplifier U4 to receive a reference voltage, so that the difference between the first voltage difference output by the second operational amplifier U4 and the reference voltage remains within a certain range. In this way, by adjusting the magnitude of the reference voltage, the first voltage difference output by the second operational amplifier U4 can be controlled to be within the range that can be sampled by the controller 3.

[0051] As an example, the first voltage difference can be expressed as UA=α*(UAX-UAY); wherein UAX is the first high-end voltage; UAY is the first low-end voltage; α is the gain coefficient, which can be jointly set by the gain of the first isolation amplifier chip U1 and the gain of the first subtraction sub-circuit 11.

[0052] In the above embodiment, the first input and second input terminals of the first isolation amplifier chip U1 are respectively connected to the first electrode and second electrode of the first power transistor Q1, isolating the high-voltage environment in the coil loop from the low-voltage environment at the rear end, while simultaneously acquiring the potentials across the first power transistor Q1. The first subtraction subcircuit 11 can then directly acquire the isolated first high-side potential and first low-side potential of the first power transistor Q1 from the first output and second output terminals of the first isolation amplifier chip U1, thereby obtaining a first voltage difference. The reference subcircuit 12 then adjusts the first voltage difference to a range suitable for sampling and processing by the controller 3.

[0053] Reference Figure 3 As an implementation of the reference sub-circuit 12, the reference sub-circuit 12 includes a first resistor R1, a second resistor R2, and a first operational amplifier U2; the first resistor R1 includes a first end connected to the second power supply and a second end connected to the second resistor R2 and the first operational amplifier U2; the second resistor R2 includes a first end connected to the second end of the first resistor R1 and the first operational amplifier U2, and a second end connected to the ground; the first operational amplifier U2 includes a first input end connected to the second end of the first resistor R1 and the first end of the second resistor R2, a second input end connected to the first subtraction sub-circuit 11, and an output end.

[0054] In the above embodiment, the voltage divider network formed by the first resistor R1 and the second resistor R2 divides the output voltage of the second power supply to obtain a reference voltage. The reference voltage can be adjusted by adjusting the values ​​of the first resistor and the second resistor R2. The first operational amplifier U2 acts as a buffer to buffer the reference voltage, ensuring a more stable output of the reference voltage to the first subtraction sub-circuit 11.

[0055] Reference Figure 2 As an embodiment of the second signal processing circuit 2, the second signal processing circuit 2 includes a second isolation amplifier chip U3 and a second subtraction sub-circuit 21; wherein the second isolation amplifier chip U3 includes a first input terminal connected to the first electrode of the second power tube Q2, a second input terminal connected to the second electrode of the second power tube Q2 and the ground, a first output terminal and a second output terminal connected to the second subtraction sub-circuit 21; the second subtraction sub-circuit 21 includes a first input terminal connected to the first output terminal of the second isolation amplifier chip U3, a second input terminal connected to the second output terminal of the second isolation amplifier chip U3, and an output terminal connected to the controller 3.

[0056] In some embodiments, the second subtraction sub-circuit 21 may include a third operational amplifier U5 and a fourth resistor R4; the third operational amplifier U5 includes a first input terminal connected to the first end of the fourth resistor R4 and the first output terminal of the second isolation amplifier chip U3, a second input terminal connected to the second output terminal of the second isolation amplifier chip U3, and an output terminal connected to the second end of the fourth resistor R4 and the controller 3. The first input terminal of the third operational amplifier U5 may be a non-inverting input terminal, and the second input terminal may be an inverting input terminal.

[0057] As an example, the second voltage difference can be expressed as UB=β*(UBX-UBY); wherein UBX is the second high-end voltage; UBY is the second low-end voltage; β is the gain coefficient, which can be jointly set by the gain of the second isolation amplifier chip U3 and the gain of the second subtraction sub-circuit 21.

[0058] In the above embodiment, the first and second input terminals of the second isolation amplifier chip U3 are connected to the first and second electrodes of the second power transistor Q2, respectively, isolating the high-voltage environment in the coil loop from the low-voltage environment at the rear end. This also enables acquisition of the potentials across the second power transistor Q2. The second subtraction subcircuit 21 can then directly obtain the isolated second high-side potential and second low-side potential of the second power transistor Q2 from the first and second output terminals of the second isolation amplifier chip U3, thereby obtaining a second voltage difference.

[0059] It should be noted that the principle of the second signal processing circuit 2 is consistent with the principle of the first signal processing voltage, which will not be repeated here. Since the second signal processing circuit 2 is connected to the second power tube Q2 arranged on the low side of the coil loop, the second voltage difference generated by the second signal processing circuit 2 is suitable for being sampled by the controller 3. Therefore, the reference voltage may not be connected to the second signal processing circuit 2. If the second voltage difference exceeds the operating voltage of the controller 3, the reference voltage may also be selected to be connected to the second signal processing circuit 2.

[0060] Reference Figure 4 As a further embodiment of the contactor monitoring device, the contactor monitoring device also includes a first drive circuit 4, which is connected to the control electrode of the first power tube Q1 and the controller 3, and is used to control the on and off of the first power tube Q1 according to the drive signal output by the controller 3.

[0061] Reference Figure 4 As a further embodiment of the contactor monitoring device, the contactor monitoring device also includes a second drive circuit 5, which is connected to the control electrode of the second power tube Q2 and the controller 3, and is used to control the on and off of the second power tube Q2 according to the pulse width modulation signal output by the controller 3.

[0062] Reference Figure 2 As an implementation manner of the controller 3, the controller 3 includes a first monitoring unit 31 and a second monitoring unit 32; wherein the first monitoring unit 31 is used to generate a first monitoring result according to the first voltage difference; the second monitoring unit 32 is used to generate a second monitoring result according to the second voltage difference and the pulse width modulation signal.

[0063] As an example, when the contactor is operating normally, the first power transistor Q1 is continuously conducting, acting as a conductor. Therefore, when the first power transistor Q1 is operating normally, the first voltage difference is approximately zero. That is, if the first voltage difference is approximately zero, a first monitoring result indicating that the first power transistor Q1 is operating normally is generated. The second power transistor Q2 is conducting at a certain duty cycle based on the pulse-width modulation signal. Therefore, when the contactor is operating normally, the second voltage difference can be expressed as UB0 = β*(U*(1-a%) / R)*Rds; where U represents the output voltage of the first power supply; a% represents the duty cycle of the pulse-width modulation signal; R represents the resistance of the coil; and Rds represents the on-resistance of the second power transistor Q2. Furthermore, the pulse-width modulation signal and the second voltage difference have the same frequency and opposite phases. Therefore, when the frequency of the second voltage difference is consistent with the pulse width modulation signal, the phase is opposite to the pulse width modulation signal, the low level is zero and the high level is UB0, a second monitoring result indicating that the second power tube Q2 is normal is generated. Otherwise, it indicates that the second power tube Q2 may be abnormal, resulting in problems such as unstable second voltage difference or disordered duty cycle. At this time, a second monitoring result indicating that the second power tube Q2 is abnormal is generated.

[0064] In the above embodiment, the first monitoring unit 31 and the second monitoring unit 32 can promptly feed back to the controller 3 when abnormal potentials occur at both ends of the first power transistor Q1 and the second power transistor Q2, so as to promptly handle the abnormal situation.

[0065] As a further embodiment of the controller 3, the controller 3 also includes a drive signal generating unit 33; the drive signal generating unit 33 is used to generate a drive signal and a pulse width drive signal of a power-on test state when the contactor is powered on, so as to control the first power tube Q1 to be turned on and the second power tube Q2 to be turned off; the first monitoring unit 31 is also used to generate a first monitoring result based on a first voltage difference when the first power tube Q1 is turned on and the second power tube Q2 is turned off; the second monitoring unit 32 is also used to generate a second monitoring result based on a second voltage difference when the first power tube Q1 is turned on and the second power tube Q2 is turned off.

[0066] As an example, when the first power transistor Q1 is on and the second power transistor Q2 is off, the coil loop is disconnected. When the coil loop is disconnected, an open-circuit voltage should exist across the first power transistor Q1. That is, when no current is flowing through the first power transistor Q1, the voltage across the first power transistor Q1 should be greater than zero. If the first voltage difference is approximately zero, it indicates that the first power transistor Q1 may have failed, thereby generating a first monitoring result indicating a short circuit in the first power transistor Q1. If the first power transistor Q1 is normal, a drive signal of a preset duration can be generated to keep the first power transistor Q1 on for the preset duration. If the second voltage difference is approximately zero, a second monitoring result indicating a short circuit in the second power transistor Q2 is generated. Because the first power transistor Q1 is only on for the preset duration, even if the second power transistor Q2 is short-circuited, the coil will not be in a prolonged short-circuit state, thereby improving safety during the monitoring process.

[0067] In the above embodiment, the states of the first power tube Q1 and the second power tube Q2 are pre-judged at the beginning of the contactor power-on stage. When it is ensured that the first power tube Q1 and the second power tube Q2 are both normal, the contactor enters the normal working state, thereby further improving the safety of the contactor.

[0068] As a further embodiment of the contactor monitoring device, the contactor monitoring device further includes a communication circuit connected to the controller 3 and a host computer for receiving monitoring results and transmitting the monitoring results to the host computer. As an example, the controller 3 can upload information such as the fault time and the faulty device to the host computer in real time.

[0069] In the above embodiment, the monitoring result is easily sent to the host computer via the communication circuit, so that maintenance personnel can promptly inspect and repair the contactor according to the monitoring result.

[0070] In a second aspect, in one embodiment, the present application provides a contactor, including: the contactor monitoring device as described above.

[0071] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0072] The embodiments, implementation methods and related technical features of the present application can be combined and replaced with each other without conflict.

[0073] The above are merely preferred embodiments of the present application and do not constitute any form of limitation to 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 monitoring device, characterized in that: include: a first signal processing circuit connected to the first power tube, and configured to generate a first voltage difference according to the potentials at both ends of the first power tube; a second signal processing circuit connected to the second power tube and configured to generate a second voltage difference according to the potentials at both ends of the second power tube; wherein the first power tube, the second power tube, and the coil in the contactor are connected in series; A controller is connected to the first signal processing circuit and the second signal processing circuit, and is used to generate a monitoring result according to the first voltage difference and the second voltage difference.

2. The contactor monitoring device according to claim 1, characterized in that: The first signal processing circuit includes a first isolation amplifier chip, a first subtraction subcircuit and a reference subcircuit; The first isolation amplifier chip includes a first input terminal connected to the first power supply and the first electrode of the first power tube, a second input terminal connected to the second electrode of the first power tube, and a first output terminal and a second output terminal connected to the first subtraction sub-circuit; The reference subcircuit is used to provide a reference voltage; The first subtraction subcircuit includes a first input terminal connected to the first output terminal of the first isolation amplifier chip, a second input terminal connected to the second output terminal of the first isolation amplifier chip and the reference subcircuit, and an output terminal connected to the controller.

3. The contactor monitoring device according to claim 2, characterized in that: The reference subcircuit includes a first resistor, a second resistor, and a first operational amplifier; The first resistor includes a first end connected to the second power supply and a second end connected to the second resistor and the first operational amplifier; The second resistor includes a first end connected to the second end of the first resistor and the first operational amplifier and a second end connected to ground; The first operational amplifier includes a first input terminal connected to the second end of the first resistor and the first end of the second resistor, a second input terminal connected to the first subtraction sub-circuit, and an output terminal.

4. The contactor monitoring device according to claim 1, characterized in that: The second signal processing circuit includes a second isolation amplifier chip and a second subtraction sub-circuit; The second isolation amplifier chip includes a first input terminal connected to the first electrode of the second power tube, a second input terminal connected to the second electrode of the second power tube and the ground, and a first output terminal and a second output terminal connected to the second subtraction sub-circuit; The second subtraction sub-circuit includes a first input terminal connected to the first output terminal of the second isolation amplifier chip, a second input terminal connected to the second output terminal of the second isolation amplifier chip, and an output terminal connected to the controller.

5. The contactor monitoring device according to claim 1, characterized in that: It also includes a first driving circuit connected to the control electrode of the first power tube and the controller, and is used to control the on and off of the first power tube according to the driving signal output by the controller.

6. The contactor monitoring device according to claim 5, characterized in that: It also includes a second driving circuit connected to the control electrode of the second power tube and the controller, and is used to control the on and off of the second power tube according to the pulse width modulation signal output by the controller.

7. The contactor monitoring device according to claim 6, characterized in that: The monitoring result includes a first monitoring result for characterizing the state of the first power tube and a second monitoring result for characterizing the state of the second power tube; The controller includes a first monitoring unit and a second monitoring unit; The first monitoring unit is configured to generate the first monitoring result according to the first voltage difference; The second monitoring unit is configured to generate the second monitoring result according to the second voltage difference and the pulse width modulation signal.

8. The contactor monitoring device according to claim 7, characterized in that: The controller further includes a drive signal generating unit; The drive signal generating unit is used to generate a drive signal for a power-on test state and a pulse width drive signal when the contactor is powered on, so as to control the first power tube to be turned on and the second power tube to be turned off; The first monitoring unit is further configured to generate a first monitoring result according to a first voltage difference between the first power tube being on and the second power tube being off; The second monitoring unit is further configured to generate a second monitoring result according to a second voltage difference when the first power tube is turned on and the second power tube is turned off.

9. The contactor monitoring device according to any one of claims 1 to 8, characterized in that: It also includes a communication circuit, which is connected to the controller and the host computer and is used to receive the monitoring results and send the monitoring results to the host computer.

10. A contactor, characterized in that: include: A contactor monitoring device according to any one of claims 1 to 9.

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