An excitation coil insulation detection circuit of an electromagnetic iron remover

Abstract

The application discloses an excitation coil insulation detection circuit of an electromagnetic iron remover, which comprises a balance bridge detection module, a protection module and a comparison module. The first end of the balance bridge detection module is connected with the first end of the excitation coil and connected with the positive pole of a direct current power supply, and the second end of the balance bridge detection module is connected with the second end of the excitation coil and connected with the negative pole of the direct current power supply, so as to obtain the ground insulation state of the excitation coil and output a first voltage detection signal corresponding to the insulation state. The first end of the protection module is connected with the output end of the balance bridge detection module, so as to process the first voltage detection signal and generate a second voltage detection signal. The first end of the comparison module is connected with the second end of the protection module, so as to compare the second voltage detection signal with a preset threshold value and generate a state signal. The excitation coil insulation detection circuit provided by the application can perform online detection on the insulation state of the excitation coil, has extremely high reliability and stability, and has extremely low cost.

Description

Technical Field

[0001] This invention relates to the field of insulation testing technology for electromagnetic separators, and more particularly to an insulation testing circuit for the excitation coil of an electromagnetic separator. Background Technology

[0002] Electromagnetic separators are key equipment in industries such as mining, building materials, coal, and metallurgy. They are mainly used to remove ferromagnetic impurities from bulk materials, preventing these impurities from damaging subsequent core equipment such as crushing and grinding, and ensuring the stable operation of the entire production line. The core component of an electromagnetic separator is the excitation coil, which generates a strong magnetic field through DC power to attract iron impurities. Its operating status directly determines the reliability and service life of the equipment.

[0003] Existing equipment for detecting the insulation status of excitation coils in electromagnetic separators falls into two categories: traditional offline insulation testing and general-purpose DC insulation testing. Traditional offline methods are unreliable, with testing cycles entirely dependent on the experience of maintenance personnel, often resulting in oversights. General-purpose DC insulation testing systems are also available, but these are too expensive, unreliable, and unsuitable for harsh outdoor conditions. In environments with dust and vibration, such as mines, they are prone to program crashes and freezes, and their long-term stability is insufficient, failing to meet the requirements for maintenance-free operation. Therefore, existing online insulation testing equipment for electromagnetic separator excitation coils suffers from low stability, poor reliability, and high cost. Summary of the Invention

[0004] This invention provides an insulation detection circuit for the excitation coil of an electromagnetic separator to solve the problems of low stability, poor reliability, and high cost of existing excitation coil insulation detection equipment.

[0005] According to one aspect of the present invention, an insulation detection circuit for an excitation coil of an electromagnetic separator is provided, comprising a balanced bridge detection module, a protection module, and a comparison module; The first end of the balanced bridge detection module is connected to the first end of the excitation coil and connected to the positive terminal of the DC power supply; the second end of the balanced bridge detection module is connected to the second end of the excitation coil and connected to the negative terminal of the DC power supply; the balanced bridge detection module is used to obtain the insulation state of the excitation coil to ground and output a first voltage detection signal corresponding to the insulation state. The first terminal of the protection module is connected to the output terminal of the balanced bridge detection module. The protection module is used to process the first voltage detection signal and generate a second voltage detection signal; wherein the voltage of the second voltage detection signal is less than the voltage of the first voltage detection signal. The first end of the comparison module is connected to the second end of the protection module. The comparison module is used to compare the second voltage detection signal with a preset threshold and generate a status signal.

[0006] Optionally, the balanced bridge detection module includes a first impedance unit and a second impedance unit; The first end of the first impedance unit is connected to the first end of the excitation coil, the second end of the first impedance unit is connected to the first end of the second impedance unit, the second end of the second impedance unit is connected to the second end of the excitation coil, and the second end of the first impedance unit and the first end of the second impedance unit serve as the output end of the balanced bridge detection module.

[0007] Optionally, the first impedance unit includes a first resistor, and the second impedance unit includes a second resistor; The first end of the first resistor is connected to the first end of the excitation coil, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the second end of the excitation coil, and the second end of the first resistor and the first end of the second resistor serve as the output end of the balanced bridge detection module. Wherein, the resistance value of the first resistor is equal to the resistance value of the second resistor.

[0008] Optionally, the protection module includes a voltage divider unit and a surge suppression unit; The first end of the voltage divider unit is connected to the output end of the balanced bridge detection module, the second end of the voltage divider unit is connected to the first end of the surge suppression unit, and the third end of the voltage divider unit is grounded. The second end of the surge suppression unit serves as the second end of the protection module and is connected to the first end of the comparison module. The third end of the surge suppression unit is grounded.

[0009] Optionally, the voltage divider unit includes a first voltage divider resistor and a second voltage divider resistor; The first end of the first voltage divider resistor serves as the first end of the voltage divider unit and is connected to the output end of the balanced bridge detection module; the second end of the first voltage divider resistor is connected to the first end of the surge suppression unit. The first end of the second voltage divider resistor is connected to the second end of the first voltage divider resistor, and the second end of the second voltage divider resistor is grounded.

[0010] Optionally, the surge suppression unit includes a current-limiting resistor and a bidirectional transient voltage suppression diode; The first end of the current-limiting resistor serves as the first end of the surge suppression unit and is connected to the second end of the voltage divider unit. The second end of the current-limiting resistor serves as the second end of the surge suppression unit and is connected to the first end of the comparison module. The first terminal of the bidirectional transient voltage suppressor diode is connected to the second terminal of the current limiting resistor, and the second terminal of the bidirectional transient voltage suppressor diode is grounded.

[0011] Optionally, the comparison module includes a preset threshold generation unit and a comparison unit; The first output terminal of the preset threshold generation unit is connected to the first pin of the comparison unit, and the second output terminal of the preset threshold generation unit is connected to the second pin of the comparison unit; the preset threshold generation unit is used to provide the comparison unit with the upper limit voltage and the lower limit voltage of the preset threshold. The third and fourth pins of the comparison unit are connected to the second terminal of the protection module; The comparison unit is used to determine that the excitation coil is in a normal state when the second voltage detection signal is less than or equal to the upper limit voltage and the second voltage detection signal is greater than or equal to the lower limit voltage, and outputs a first state signal. When the second voltage detection signal is greater than the upper limit voltage or less than the lower limit voltage, the excitation coil is determined to be in an abnormal state, and a second state signal is output.

[0012] Optionally, the preset threshold generation unit includes an upper limit voltage generation subunit and a lower limit voltage generation subunit; The first terminal of the upper limit voltage generation subunit is connected to the positive terminal of the first power supply, the second terminal of the upper limit voltage generation subunit is connected to the first pin of the comparison unit, and the third terminal of the upper limit voltage generation subunit is grounded. The first terminal of the lower limit voltage generation subunit is connected to the negative terminal of the first power supply, the second terminal of the lower limit voltage generation subunit is connected to the second pin of the comparison unit, and the third terminal of the lower limit voltage generation subunit is grounded.

[0013] Optionally, the upper limit voltage generation subunit includes a third resistor and a fourth resistor; The first end of the third resistor is connected to the positive terminal of the first power supply, and the second end of the third resistor is connected to the first pin of the comparison unit; the first end of the fourth resistor is connected to the second end of the third resistor, and the second end of the fourth resistor is grounded. The lower limit voltage generation subunit includes a fifth resistor and a sixth resistor; The first end of the fifth resistor is connected to the negative terminal of the first power supply, and the second end of the fifth resistor is connected to the second pin of the comparison unit; the first end of the sixth resistor is connected to the second end of the fifth resistor, and the second end of the sixth resistor is grounded.

[0014] Optionally, the excitation coil insulation detection circuit may further include an alarm module; The first end of the alarm module is connected to the second end of the comparison module; the alarm module is used to issue an alarm message when the comparison module outputs the second status signal.

[0015] The technical solution of this invention uses a balanced bridge detection module and the insulation resistance of the positive and negative poles of the excitation coil to ground to form a four-arm balanced bridge. The change in the insulation resistance of the excitation coil to ground is converted into the offset of the voltage to ground at the output terminal of the balanced bridge detection module, and a corresponding voltage detection signal is output. The protection module processes the voltage detection signal to generate a second voltage detection signal, which is then compared and judged by the comparison module. This achieves accurate sensing of the insulation status at extremely low cost and accurate early warning without blind spots throughout the entire process. It greatly improves the reliability and practicality of the monitoring system, can be adapted to complex outdoor working conditions such as mines and sand and gravel pits, avoids serious faults such as coil breakdown and burnout, can extend the service life of the excitation coil, and significantly reduce the maintenance cost of the equipment.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the structure of an insulation detection circuit for an electromagnetic separator provided in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of an excitation coil insulation detection circuit for an electromagnetic separator provided in an embodiment of the present invention; Figure 3 A schematic diagram of the structure of an excitation coil insulation detection circuit for an electromagnetic separator provided in an embodiment of the present invention; Figure 4 A schematic diagram of the structure of an excitation coil insulation detection circuit for an electromagnetic separator provided in an embodiment of the present invention; Figure 5 A schematic diagram of the structure of an excitation coil insulation detection circuit for an electromagnetic separator provided in an embodiment of the present invention; Figure 6 A schematic diagram of the structure of an excitation coil insulation detection circuit for an electromagnetic separator provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the insulation detection circuit of the excitation coil of another electromagnetic separator provided in an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] Figure 1 This is a schematic diagram of the insulation detection circuit for the excitation coil of an electromagnetic separator, provided as an embodiment of the present invention. See also... Figure 1 The electromagnetic separator's excitation coil insulation detection circuit 100 includes a balanced bridge detection module 10, a protection module 20, and a comparison module 30. The first terminal of the balanced bridge detection module 10 is connected to the first terminal of the excitation coil 200 and connected to the positive terminal of the DC power supply VCC1. The second terminal of the balanced bridge detection module 10 is connected to the second terminal of the excitation coil 200 and connected to the negative terminal of the DC power supply VCC1. The balanced bridge detection module 10 is used to acquire the insulation state of the excitation coil 200 to ground and outputs a first voltage detection signal corresponding to the insulation state. The first terminal of the protection module 20 is connected to the output terminal of the balanced bridge detection module 10, and the protection module 20 is used to process the first voltage detection signal and generate a second voltage detection signal. The first terminal of the comparison module 30 is connected to the second terminal of the protection module 20, and the comparison module 30 is used to compare the second voltage detection signal with a preset threshold and generate a status signal.

[0022] Specifically, this invention provides an insulation detection circuit 100 for the excitation coil of an electromagnetic separator, which can monitor the insulation performance of the excitation coil of the electromagnetic separator online. The electromagnetic separator, connected to a DC power supply VCC1, generates a stable, strong, and constant magnetic field through its excitation coil. When the electromagnetic separator detects ferromagnetic impurities (such as bolts, steel balls, or shovel teeth) mixed below, these impurities are attracted to the bottom of the separator by the strong magnetic field, thus separating the iron impurities from the material and ensuring the safe operation of the subsequent production line. Electromagnetic separators typically require continuous 24-hour operation, with the excitation coil constantly energized. Therefore, the insulation state of the coil directly determines the service life and operational reliability of the equipment. If insulation deterioration is not detected in time, it can lead to coil breakdown and burnout, causing unplanned downtime. The excitation coil insulation detection circuit 100 provided by this invention can perform online detection of the excitation coil 200 of the electromagnetic separator. The first and second terminals of the balanced bridge detection module 10 are respectively connected to the first and second terminals of the excitation coil 200 and connected to the positive and negative terminals of the DC power supply VCC1. The DC power supply VCC1 can have a voltage of 200V. The balanced bridge detection module 10 and the insulation resistance to ground of the excitation coil 200 of the electromagnetic separator together form a four-arm balanced bridge. When the insulation resistance to ground on both sides of the excitation coil 200 is symmetrical, the output potential of the balanced bridge detection module 10 is zero or close to zero. When the insulation resistance to ground on either the positive or negative side of the excitation coil 200 deteriorates asymmetrically, the output potential to ground of the balanced bridge detection module 10 shifts positively or negatively, and the magnitude of this shift is directly proportional to the degree of insulation deterioration. Thus, the balanced bridge detection module 10 converts the insulation state of the excitation coil 200 into a measurable first voltage detection signal for subsequent circuitry to identify and judge. The protection module 20 performs voltage reduction and filtering on the first voltage detection signal output from the balanced bridge detection module 10, converting it into a second voltage detection signal with appropriate amplitude and stable waveform, preventing damage to subsequent circuitry from the high-voltage first voltage detection signal. The protection module 20 processes the first voltage detection signal, converting it into a second voltage detection signal with appropriate amplitude and stable waveform to ensure the normal detection operation of subsequent circuits. The first terminal of the comparison module 30 is connected to the second terminal of the protection module 20. The comparison module 30 can compare the received second voltage detection signal with a preset threshold and output a corresponding status signal. When the second voltage detection signal falls within the preset threshold, the insulation state of the excitation coil 200 is determined to be normal, and a normal status signal is output. When the second voltage detection signal exceeds the preset threshold, the insulation state of the excitation coil 200 is determined to be abnormal, and an abnormal status signal is output. The status signal can be used to drive alarm devices (such as indicator lights and buzzers) or uploaded to a remote control system via an isolation circuit to achieve real-time online early warning of insulation faults.

[0023] The electromagnetic separator excitation coil insulation detection circuit provided in this embodiment of the invention uses a balanced bridge detection module and the insulation resistance of the positive and negative poles of the excitation coil to ground to form a four-arm balanced bridge. The change in the insulation resistance of the excitation coil to ground is converted into the offset of the voltage to ground at the output terminal of the balanced bridge detection module, and a corresponding first voltage detection signal is output. The protection module processes the first voltage detection signal to generate a second voltage detection signal, which is then compared and judged by the comparison module. This achieves accurate sensing of the insulation status at extremely low cost and accurate early warning without blind spots throughout the entire process, greatly improving the reliability and practicality of the monitoring system. It can be adapted to complex outdoor working conditions such as mines and sand and gravel pits, avoiding serious faults such as coil breakdown and burnout, extending the service life of the excitation coil, and significantly reducing the maintenance cost of the equipment.

[0024] Optional, Figure 2 This is a schematic diagram of the insulation detection circuit for the excitation coil of an electromagnetic separator, provided as an embodiment of the present invention. Based on the above embodiments, see [link to other embodiments]. Figure 2 The balanced bridge detection module 10 includes a first impedance unit 11 and a second impedance unit 12. The first end of the first impedance unit 11 is connected to the first end of the excitation coil 200, the second end of the first impedance unit 11 is connected to the first end of the second impedance unit 12, and the second end of the second impedance unit 12 is connected to the second end of the excitation coil 200. The second end of the first impedance unit 11 and the first end of the second impedance unit 12 serve as the output terminals of the balanced bridge detection module 10.

[0025] Specifically, the balanced bridge detection module 10 may include a first impedance unit 11 and a second impedance unit 12. The first end of the first impedance unit 11 is connected to the first end of the excitation coil 200 and is connected to the positive terminal of the DC power supply VCC1. The second end of the first impedance unit 11 is connected to the first end of the second impedance unit 12. The second end of the second impedance unit 12 is connected to the second end of the excitation coil 200 and is connected to the negative terminal of the DC power supply VCC1. The common connection point between the second end of the first impedance unit 11 and the first end of the second impedance unit 12 serves as the output terminal of the balanced bridge detection module 10. This common connection point can be used as the detection midpoint to output a first voltage detection signal. The first impedance unit 11 and the second impedance unit 12 are connected in series and are connected in series between the positive and negative terminals of the DC power supply VCC1 to form a series voltage divider branch. Together with the insulation resistance of the positive and negative terminals of the excitation coil 200 of the electromagnetic separator to ground, they form a four-arm balanced bridge. The change in the insulation resistance of the excitation coil 200 to ground can be converted into the offset of the detection midpoint voltage to ground of the first impedance unit 11 and the second impedance unit 12, and the corresponding first voltage detection signal is output.

[0026] Optionally, based on the above embodiments, see also... Figure 2The first impedance unit 11 includes a first resistor R1, and the second impedance unit 12 includes a second resistor R2. The first end of the first resistor R1 is connected to the first end of the excitation coil 200, the second end of the first resistor R1 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is connected to the second end of the excitation coil 200. The second end of the first resistor R1 and the first end of the second resistor R2 serve as the output terminals of the balanced bridge detection module 10.

[0027] Specifically, the first impedance unit 11 includes a first resistor R1, and the second impedance unit 12 includes a second resistor R2. The first resistor R1 and the second resistor R2, together with the equivalent insulation resistance to ground on the positive side and the equivalent insulation resistance to ground on the negative side of the excitation coil 200, form a four-arm balanced bridge. The resistance value of the first resistor R1 is equal to the resistance value of the second resistor R2. For example, the DC power supply VCC1 has a voltage of 200V, and the equivalent insulation resistance to ground on the positive side of the excitation coil 200 is... The equivalent insulation resistance of the 200 Ω negative pole of the excitation coil to ground is The first resistor R1 and the second resistor R2 form the upper half of the bridge arm of the Wheatstone bridge. The equivalent insulation resistance of the positive terminal to ground is... Equivalent insulation resistance between negative electrode and ground The lower half of the bridge arm forms the midpoint of the detection circuit, which is the common connection point of the first resistor R1 and the second resistor R2. According to Kirchhoff's current law, the leakage current flowing into the ground from the positive terminal through the insulation resistance is equal in magnitude and opposite in direction to the leakage current flowing out of the ground from the negative terminal through the insulation resistance. This means the total leakage current between the 200 poles of the excitation coil and ground is zero, thus satisfying the current balance relationship between the positive and negative poles and ground. .

[0028] Where V+ is the potential of the positive terminal of excitation coil 200 relative to ground, and V- is the potential of the negative terminal of excitation coil 200 relative to ground, and satisfies .in, For example, the total voltage of the DC power supply VCC1. It is 200V.

[0029] Since R1=R2, the potential at the detection midpoint is the arithmetic mean of the potentials of the positive and negative sides of the excitation coil 200 relative to ground, that is, Combining the above equations, we get: .

[0030] From the above formula, it can be seen that the voltage at the midpoint is detected. Insulation resistance between the positive terminal of the excitation coil 200 and ground Insulation resistance between the negative electrode and ground Related. When the insulation on both sides of the excitation coil 200 is good and symmetrical, ,at this time The bridge circuit is in a balanced state. When the insulation on one side of the excitation coil 200 deteriorates, the voltage at the midpoint is detected. A shift occurs. For example, the insulation resistance on the negative side. It dropped to the warning threshold, while the positive electrode side When it is still within the normal range, and The symmetry is broken. This will result in a positive offset; conversely, if the insulation on the positive side deteriorates, This will generate a negative offset. As can be seen, the balanced bridge detection module 10 converts the insulation state to ground into a voltage offset signal by detecting the midpoint. The direction of the offset can represent whether the insulation degradation occurs on the positive or negative side of the excitation coil 200, and the magnitude of the offset reflects the degree of insulation degradation.

[0031] Specifically, the first resistor R1 and the second resistor R2 can be precision resistors with a resistance of 2MΩ to ensure that the total current in the voltage divider circuit of the first resistor R1 and the second resistor R2 is extremely small, the power consumption of the whole machine is in the microwatt range, and it consumes almost no excitation power, so as not to affect the normal operation of the iron separator. The high resistance of the first resistor R1 and the second resistor R2 is on the same order of magnitude as the insulation resistance of the excitation coil 200. When the insulation resistance changes, it can produce a significant voltage shift, ensuring detection sensitivity. In addition, the use of megohm-level resistors ensures that the leakage current is extremely low, which meets the safety specifications for insulation detection of high-voltage equipment. Furthermore, the first resistor R1 and the second resistor R2 are selected with an accuracy of 1% and the same temperature coefficient, which can effectively offset the influence of temperature changes on detection accuracy and ensure that the bridge remains balanced over a wide temperature range.

[0032] Specifically, under normal operating conditions, the excitation coil 200 of the electromagnetic separator has good insulation performance. The resistance near the positive and negative terminals of the excitation coil 200 is extremely high (typically greater than 500MΩ), and the insulation levels on both sides are basically symmetrical. At this time, the bridge circuit is in a balanced state, and the voltage at the midpoint to ground is approximately 0V. When the excitation coil experiences problems such as moisture or insulation aging, the insulation resistance to ground on the corresponding side will gradually decrease, disrupting the original bridge balance and causing a positive or negative shift in the voltage at the midpoint to ground. If the insulation fault occurs near the positive terminal of the power supply, the resistance on the positive side of the excitation coil 200 decreases, the overall system potential shifts negatively to ground, and the voltage at the midpoint to ground becomes negative. If the fault occurs near the negative terminal, the resistance on the negative side of the excitation coil 200 decreases, the overall system potential shifts positively to ground, and the voltage at the midpoint to ground becomes positive. By detecting the direction and magnitude of the voltage deviation at the midpoint, the change in insulation resistance and fault location of the excitation coil 200 can be accurately sensed, achieving blind-spot-free detection of the entire excitation coil 200.

[0033] Optional, Figure 3This is a schematic diagram of the insulation detection circuit for the excitation coil of an electromagnetic separator, provided as an embodiment of the present invention. Based on the above embodiments, see [link to other embodiments]. Figure 3 The protection module 20 includes a voltage divider unit 21 and a surge suppression unit 22. The first terminal of the voltage divider unit 21 is connected to the output terminal of the balanced bridge detection module 10, the second terminal of the voltage divider unit 21 is connected to the first terminal of the surge suppression unit 22, and the third terminal of the voltage divider unit 21 is grounded. The second terminal of the surge suppression unit 22 serves as the second terminal of the protection module 20 and is connected to the first terminal of the comparison module 30; the third terminal of the surge suppression unit 22 is grounded.

[0034] Specifically, the voltage of the first voltage detection signal at the midpoint of the balanced bridge detection module 10 is relatively high, far exceeding the safe input voltage range of the downstream module. The protection module 20 can perform voltage division processing on the first voltage detection signal to generate a second voltage detection signal. The protection module 20 is composed of a voltage divider unit 21 and a surge suppression unit 22 cascaded in sequence. The first end of the voltage divider unit 21 is connected to the output end (i.e., the midpoint of the detection) of the balanced bridge detection module 10, and is used to receive the first voltage detection signal output by the balanced bridge detection module 10. The second end of the voltage divider unit 21 is connected to the first end of the surge suppression unit 22, and is used to transmit the detection signal after voltage division and attenuation to the surge suppression unit 22. The second end of the surge suppression unit 22 serves as the second end of the protection module 20, and is connected to the first end of the comparison module 30, and is used to output the second voltage detection signal after voltage division and surge suppression processing to the comparison module 30.

[0035] Optional, Figure 4 This is a schematic diagram of the insulation detection circuit for the excitation coil of an electromagnetic separator, provided as an embodiment of the present invention. Based on the above embodiments, see [link to other embodiments]. Figure 4 The voltage divider unit 21 includes a first voltage divider resistor R3 and a second voltage divider resistor R4. The first terminal of the first voltage divider resistor R3 serves as the first terminal of the voltage divider unit 21 and is connected to the third terminal of the balanced bridge detection module 10. The second terminal of the first voltage divider resistor R3 is connected to the first terminal of the surge suppression unit 22. The first terminal of the second voltage divider resistor R4 is connected to the second terminal of the first voltage divider resistor R3, and the second terminal of the second voltage divider resistor R4 is grounded.

[0036] Specifically, the voltage divider unit 21 may include a first voltage divider resistor R3 and a second voltage divider resistor R4. The first end of the first voltage divider resistor R3 serves as the first end of the voltage divider unit 21 and is connected to the output terminal (detection midpoint) of the balanced bridge detection module 10. The second end of the first voltage divider resistor R3 is connected to the first end of the surge suppression unit 22. That is, the first voltage divider resistor R3 is connected in series in the signal loop between the detection midpoint and the input terminal of the surge suppression unit 22, used to initially reduce the voltage of the first voltage detection signal output from the detection midpoint M. The first end of the second voltage divider resistor R4 is connected to the second end of the first voltage divider resistor R3, that is, the first end of the second voltage divider resistor R4 is connected to the common connection point of the first voltage divider resistor R3 and the surge suppression unit 22. The second end of the second voltage divider resistor R4 is grounded. In other words, the second voltage divider resistor R4 is connected in parallel between the output terminal of the first voltage divider resistor R3 and ground. The voltage signal from the detection midpoint is first connected to the first voltage divider resistor R3 and the second voltage divider resistor R4 before being grounded, reducing the high-voltage first voltage detection signal from the detection midpoint to within a preset voltage range by a fixed ratio. For example, the voltage range can be within ±2V, adapting to the input voltage range of the subsequent comparator module 30. At the same time, it maintains extremely high input impedance without disrupting the balance of the original bridge.

[0037] In this design, the first voltage divider resistor R3 has a resistance of 10MΩ, and the second voltage divider resistor R4 has a resistance of 200kΩ. The voltage division ratio formed by the two resistors is... In other words, the voltage divider unit 21 attenuates the first voltage detection signal at the detection midpoint to approximately 1 / 51 of its original amplitude. When the excitation coil 200 experiences unilateral insulation degradation, the voltage at the detection midpoint can shift to approximately ±90V. After being attenuated by the voltage divider unit 21 at a ratio of 51:1, the output voltage is approximately ±1.8V, to match the safe input range of the subsequent comparator module 30. Moreover, the first voltage divider resistor R3 uses a high resistance value of 10MΩ, making the input impedance of the voltage divider unit 21 extremely high, with almost no current shunting, and thus having almost no impact on the detection accuracy of the front-end balanced bridge detection module 10. The 10MΩ input impedance is much greater than the resistance values ​​of the first resistor R1 and the second resistor R2 in the balanced bridge detection module 10. Therefore, the shunting current introduced by the voltage divider unit 21 from the detection midpoint is extremely small and negligible, thereby ensuring that the original voltage division relationship of the balanced bridge detection module 10 is not disrupted.

[0038] Optionally, based on the above embodiments, see also... Figure 4The surge suppression unit 22 includes a current-limiting resistor R5 and a bidirectional transient voltage suppression diode D1. The first terminal of the current-limiting resistor R5 serves as the first terminal of the surge suppression unit 22 and is connected to the second terminal of the voltage divider unit 21. The second terminal of the current-limiting resistor R5 serves as the second terminal of the surge suppression unit 22 and is connected to the first terminal of the comparator module 30. The first terminal of the bidirectional transient voltage suppression diode D1 is connected to the second terminal of the current-limiting resistor R5, and the second terminal of the bidirectional transient voltage suppression diode D1 is grounded.

[0039] Specifically, the surge suppression unit 22 may include a current-limiting resistor R5 and a bidirectional transient voltage suppression diode D1. The first end of the current-limiting resistor R5 serves as the first end of the surge suppression unit 22, connected to the second end of the voltage divider unit 21, which is the common connection point of the first voltage divider resistor R3 and the second voltage divider resistor R4. The second end of the current-limiting resistor R5 serves as the second end of the surge suppression unit 22, connected to the first end of the comparator module 30. The current-limiting resistor R5 is connected in series in the signal loop between the output of the voltage divider unit 21 and the input of the comparator module 30, used to limit the current flowing into the subsequent circuit when a surge occurs. The first end of the bidirectional transient voltage suppression diode D1 is connected to the second end of the current-limiting resistor R5, and the second end of the bidirectional transient voltage suppression diode D1 is grounded. That is, the bidirectional transient voltage suppression diode D1 is connected in parallel between the input of the comparator module 30 and ground, used to quickly absorb instantaneous high voltages caused by lightning induction and switching operation overvoltages, clamping the voltage at the input of the comparator module 30 within a safe range, and preventing high voltage spikes from damaging the subsequent comparator module 30.

[0040] The current-limiting resistor R5 can have a resistance of 1kΩ, which limits the loop current under fault conditions, further protecting the downstream circuit and preventing overcurrent damage. The turn-off voltage of the bidirectional transient voltage suppressor diode D1 can be greater than or equal to ±3V, which is higher than the maximum value of the normal second voltage detection signal. This ensures that the bidirectional transient voltage suppressor diode D1 is in the cut-off state under normal operating conditions, and will not affect the transmission of the detection signal. This solves the problem that the detection circuit is easily damaged by overvoltage and greatly improves the circuit's anti-interference capability.

[0041] Optional, Figure 5 This is a schematic diagram of the insulation detection circuit for the excitation coil of an electromagnetic separator, provided as an embodiment of the present invention. Based on the above embodiments, see [link to other embodiments]. Figure 5The comparison module 30 includes a preset threshold generation unit 31 and a comparison unit 32. The first output terminal of the preset threshold generation unit 31 is connected to the first pin of the comparison unit 32, and the second output terminal of the preset threshold generation unit 31 is connected to the second pin of the comparison unit 32. The preset threshold generation unit 31 provides the comparison unit 32 with an upper and lower limit voltage of the preset threshold. The third and fourth pins of the comparison unit 32 are connected to the second terminal of the protection module 20. The comparison unit 32 determines that the excitation coil 200 is in a normal state and outputs a first state signal when the second voltage detection signal is less than or equal to the upper limit voltage and greater than or equal to the lower limit voltage. It also determines that the excitation coil 200 is in an abnormal state and outputs a second state signal when the second voltage detection signal is greater than the upper limit voltage or less than the lower limit voltage.

[0042] Specifically, the comparison module 30 may include a preset threshold generation unit 31 and a comparison unit 32. The first output terminal of the preset threshold generation unit 31 is connected to the first pin of the comparison unit 32, and the second output terminal of the preset threshold generation unit 31 is connected to the second pin of the comparison unit 32. The preset threshold generation unit 31 provides the comparison unit 32 with an upper and lower limit voltage of a preset threshold. The third and fourth pins of the comparison unit 32 are both connected to the second terminal of the protection module 20 and are used to receive the second voltage detection signal output by the protection module 20. When the second voltage detection signal is less than or equal to the upper limit voltage and greater than or equal to the lower limit voltage, the excitation coil 200 is determined to be in a normal state, and a first state signal is output. When the second voltage detection signal is greater than the upper limit voltage or less than the lower limit voltage, the excitation coil 200 is determined to be in an abnormal state, and a second state signal is output. The first state signal can be a high-level signal, and the second state signal can be a low-level signal.

[0043] The comparator unit 32 can be a dual-channel voltage comparator of model LM393, which includes two independent comparators: an upper limit comparator 321 and a lower limit comparator 322. These are used to compare the positive upper limit and negative lower limit of the second voltage detection signal, respectively, forming a symmetrical voltage detection window. The non-inverting input of the upper limit comparator 321 serves as the first pin of the comparator unit 32, connected to the upper limit voltage, while the inverting input serves as the third pin, connected to the second voltage detection signal. The non-inverting input of the lower limit comparator 322 serves as the fourth pin, connected to the second voltage detection signal, while the inverting input serves as the second pin, connected to the lower limit voltage. The outputs of the upper limit comparator 321 and the lower limit comparator 322 can be connected together as the output of the comparator unit 32. An external pull-up resistor is also required at the output of the comparator unit 32, connected to a 12V power supply. When the second voltage detection signal is within a preset threshold range (less than or equal to the upper limit voltage and greater than or equal to the lower limit voltage), both the upper limit comparator 321 and the lower limit comparator 322 are in the off state, and the output terminals present a high impedance state. An external pull-up resistor is required at the output terminals to output a high-level first state signal. The upper limit comparator 321 compares the second voltage detection signal with the upper limit voltage. When the second voltage detection signal is greater than the upper limit voltage, the upper limit comparator 321 is triggered, and the lower limit comparator 322 is in the off state, outputting a low-level second state signal. The lower limit comparator 322 compares the second voltage detection signal with the lower limit voltage. When the second voltage detection signal is less than the lower limit voltage, the lower limit comparator 322 is triggered, and the upper limit comparator 321 is in the off state, outputting a low-level second state signal.

[0044] Optional, Figure 6 This is a schematic diagram of the insulation detection circuit for the excitation coil of an electromagnetic separator, provided as an embodiment of the present invention. Based on the above embodiments, see [link to other embodiments]. Figure 6 The preset threshold generation unit 31 includes an upper limit voltage generation subunit 311 and a lower limit voltage generation subunit 312. The first terminal of the upper limit voltage generation subunit 311 is connected to the positive terminal of the first power supply VCC2, the second terminal of the upper limit voltage generation subunit 311 is connected to the first pin of the comparison unit 32, and the third terminal of the upper limit voltage generation subunit 311 is grounded. The first terminal of the lower limit voltage generation subunit 312 is connected to the negative terminal of the first power supply VCC2, the second terminal of the lower limit voltage generation subunit 312 is connected to the second pin of the comparison unit 32, and the third terminal of the lower limit voltage generation subunit 312 is grounded.

[0045] Specifically, the preset threshold generation unit 31 may include an upper limit voltage generation subunit 311 and a lower limit voltage generation subunit 312. The upper limit voltage generation subunit 311 divides the positive voltage of the first power supply VCC2 to generate an upper limit voltage of the preset threshold, and outputs it to the first pin of the comparison unit 32 through its second terminal. The lower limit voltage generation subunit 312 divides the negative voltage of the first power supply VCC2 to generate a lower limit voltage of the preset threshold, and outputs it to the second pin of the comparison unit 32 through its second terminal. The first power supply VCC2 can be a ±12V DC power supply.

[0046] Optionally, based on the above embodiments, see also... Figure 6 The upper limit voltage generation subunit 311 includes a third resistor R6 and a fourth resistor R7. The first terminal of the third resistor R6 is connected to the positive terminal of the first power supply VCC2, and the second terminal of the third resistor R6 is connected to the first pin of the comparator unit 32. The first terminal of the fourth resistor R7 is connected to the second terminal of the third resistor R6, and the second terminal of the fourth resistor R7 is grounded. The lower limit voltage generation subunit 312 includes a fifth resistor R8 and a sixth resistor R9. The first terminal of the fifth resistor R8 is connected to the negative terminal of the first power supply VCC2, and the second terminal of the fifth resistor R8 is connected to the second pin of the comparator unit 32. The first terminal of the sixth resistor R9 is connected to the second terminal of the fifth resistor R8, and the second terminal of the sixth resistor R9 is grounded.

[0047] Specifically, the third resistor R6 and the fourth resistor R7 are connected in series between the positive terminal of the first power supply VCC2 and ground, forming a series voltage divider circuit. The common connection point of the third resistor R6 and the fourth resistor R7 serves as the second terminal of the upper limit voltage generation subunit 311, outputting the upper limit voltage to the first pin of the comparator unit 32. The second terminal of the sixth resistor R9 is grounded. The fifth resistor R8 and the sixth resistor R9 are connected in series between the negative terminal of the first power supply VCC2 and ground, forming a series voltage divider circuit. The common connection point of the fifth resistor R8 and the sixth resistor R9 serves as the second terminal of the lower limit voltage generation subunit 312, outputting the lower limit voltage to the second pin of the comparator unit 32.

[0048] For example, the resistance values ​​of the third resistor R6 and the fifth resistor R8 are both 11kΩ, and the resistance values ​​of the fourth resistor R7 and the sixth resistor R9 are both 1kΩ. The first power supply VCC2 can be a ±12V power supply. The upper limit voltage... The upper limit voltage can be calculated to be +1V. The lower limit voltage... Calculations show that the lower limit voltage is -1V, and the preset threshold range is -1V to 1V. The insulation resistance between the positive terminal of the excitation coil 200 and ground... Insulation resistance between negative electrode and ground Typically 500MΩ. Under normal conditions, the voltage at the detection midpoint is 0V. An alarm can be triggered when the insulation resistance between the excitation coil 200Ω and ground drops to approximately 5MΩ. The first resistor R1 and the second resistor R2 are 2MΩ, and the DC power supply VCC1 is 200V. When the insulation on the negative side deteriorates to... At this point, the total equivalent resistance of the negative terminal to ground is approximately 5 MΩ, while the positive terminal to ground remains at 500 MΩ. Based on the current balance, the positive offset of the detection midpoint to ground is approximately 91.6 V. Similarly, when the insulation on the positive side deteriorates to... At that time, the negative offset of the detection midpoint to ground is approximately 91.6V. After the detection signal is divided by a 51:1 high voltage, the second voltage detection signal under fault conditions is approximately ±1.8V. Therefore, the upper limit voltage of the preset threshold is set to +1V, and the lower limit voltage is set to -1V, forming a symmetrical preset voltage window with a width of 2V. When the excitation coil insulation is normal, the second voltage detection signal is 0V, and neither comparator operates. When the insulation resistance on either side drops below the warning threshold, the second voltage detection signal will exceed the preset threshold, triggering the corresponding comparator to operate and output a fault signal.

[0049] Optional, Figure 7 This is a schematic diagram of the insulation detection circuit for the excitation coil of an electromagnetic separator, provided as an embodiment of the present invention. Based on the above embodiments, see [link to other embodiments]. Figure 7 The excitation coil insulation detection circuit 100 also includes an alarm module 40. The first terminal of the alarm module 40 is connected to the second terminal of the comparison module 30. The alarm module 40 is used to issue an alarm message when the comparison module 30 outputs a second status signal.

[0050] Specifically, the status signal output by the comparison module 30 can be connected to the alarm module 40. The second terminal of the comparison module 30 requires an external pull-up resistor R10; that is, the first terminal of the pull-up resistor R10 is connected to the output terminal of the comparison module 30, and the second terminal of the pull-up resistor R10 is connected to the first power supply VCC2. The second terminal of the comparison module 30 is also the output terminal of the upper limit comparator 321 and the lower limit comparator 322, i.e., the fifth and sixth pins of the comparison unit 32. The first power supply VCC2 can be a 12V power supply. When an insulation fault is detected in the excitation coil 200 of the electromagnetic separator, the comparison unit 32 outputs a high-level second status signal under the action of the pull-up resistor R10. The alarm module 40 responds to the second status signal output by the comparison module 30 and issues an alarm message. The alarm module 40 may include a buzzer and an alarm indicator light. Upon receiving the second status signal, the buzzer can issue a voice alarm message, and the alarm indicator light can issue a light alarm message.

[0051] During normal operation of the electromagnetic separator, the balanced bridge detection module 10 maintains balance, and the voltage at the midpoint of the detection circuit remains stable within a preset threshold. The comparison module 30 outputs a first status signal. When the insulation performance of the excitation coil 200 gradually decreases, the insulation resistance on the corresponding side decreases, and the first voltage detection signal at the midpoint drifts accordingly. When the second voltage detection signal, after being processed by the protection module 20, is no longer within the preset threshold, the comparison module 30 immediately triggers an action, outputs a second status signal, triggers the alarm module 40 to issue an alarm message, and simultaneously sends a fault message to the remote control system. After receiving the alarm, maintenance personnel can arrange maintenance during the uninterrupted production window, completely avoiding serious faults such as excitation coil breakdown and burnout, and improving the stability of the equipment.

[0052] The excitation coil insulation detection circuit of the electromagnetic separator provided in this invention uses a balanced bridge detection module and the insulation resistance of the positive and negative poles of the excitation coil to ground to form a four-arm balanced bridge. This bridge converts changes in the insulation resistance of the excitation coil to ground into a shift in the voltage at the detection midpoint to ground, and outputs a corresponding first voltage detection signal. The protection module processes the first voltage detection signal to generate a second voltage detection signal. The comparison module compares and judges the signals, and outputs a second state signal when the second voltage detection signal exceeds a preset threshold, causing the alarm module to issue an alarm message. This excitation coil insulation detection circuit has extremely low overall hardware cost, reducing overall costs. It uses pure analog hardware circuitry without any software programs, eliminating problems such as program crashes or freezes. It can perfectly adapt to the harsh working conditions of mines, including dust, humidity, and vibration, and can operate stably for a long time with a long maintenance-free period. The precise early warning without blind spots can immediately trigger an alarm when the insulation resistance drops to the warning threshold, providing early warning of insulation faults. This allows maintenance personnel sufficient time to arrange repairs, completely avoiding serious faults such as coil breakdown and burnout, extending the life of the excitation coil, and significantly reducing equipment maintenance costs. The protection module effectively resists interference from lightning strikes and switching overvoltages, reduces false alarms, and ensures long-term stable operation of the system. It solves the problems of general monitoring circuits being prone to damage and false alarms under outdoor conditions. Furthermore, this excitation coil insulation detection circuit has a wide range of applications and can be used in various devices, resulting in significant economic benefits.

[0053] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. An insulation detection circuit for the excitation coil of an electromagnetic separator, characterized in that, include: Balanced bridge detection module, protection module, and comparison module; The first end of the balanced bridge detection module is connected to the first end of the excitation coil and connected to the positive terminal of the DC power supply; the second end of the balanced bridge detection module is connected to the second end of the excitation coil and connected to the negative terminal of the DC power supply; the balanced bridge detection module is used to obtain the insulation state of the excitation coil to ground and output a first voltage detection signal corresponding to the insulation state. The first terminal of the protection module is connected to the output terminal of the balanced bridge detection module. The protection module is used to process the first voltage detection signal and generate a second voltage detection signal; wherein the voltage of the second voltage detection signal is less than the voltage of the first voltage detection signal. The first end of the comparison module is connected to the second end of the protection module. The comparison module is used to compare the second voltage detection signal with a preset threshold and generate a status signal.

2. The excitation coil insulation detection circuit according to claim 1, characterized in that, The balanced bridge detection module includes a first impedance unit and a second impedance unit. The first end of the first impedance unit is connected to the first end of the excitation coil, the second end of the first impedance unit is connected to the first end of the second impedance unit, the second end of the second impedance unit is connected to the second end of the excitation coil, and the second end of the first impedance unit and the first end of the second impedance unit serve as the output end of the balanced bridge detection module.

3. The excitation coil insulation detection circuit according to claim 2, characterized in that, The first impedance unit includes a first resistor, and the second impedance unit includes a second resistor; The first end of the first resistor is connected to the first end of the excitation coil, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the second end of the excitation coil, and the second end of the first resistor and the first end of the second resistor serve as the output end of the balanced bridge detection module. Wherein, the resistance value of the first resistor is equal to the resistance value of the second resistor.

4. The excitation coil insulation detection circuit according to claim 1, characterized in that, The protection module includes a voltage divider unit and a surge suppression unit; The first end of the voltage divider unit is connected to the output end of the balanced bridge detection module, the second end of the voltage divider unit is connected to the first end of the surge suppression unit, and the third end of the voltage divider unit is grounded. The second end of the surge suppression unit serves as the second end of the protection module and is connected to the first end of the comparison module. The third end of the surge suppression unit is grounded.

5. The excitation coil insulation detection circuit according to claim 4, characterized in that, The voltage divider unit includes a first voltage divider resistor and a second voltage divider resistor; The first end of the first voltage divider resistor serves as the first end of the voltage divider unit and is connected to the output end of the balanced bridge detection module; the second end of the first voltage divider resistor is connected to the first end of the surge suppression unit. The first end of the second voltage divider resistor is connected to the second end of the first voltage divider resistor, and the second end of the second voltage divider resistor is grounded.

6. The excitation coil insulation detection circuit according to claim 4, characterized in that, The surge suppression unit includes a current-limiting resistor and a bidirectional transient voltage suppression diode; The first end of the current-limiting resistor serves as the first end of the surge suppression unit and is connected to the second end of the voltage divider unit. The second end of the current-limiting resistor serves as the second end of the surge suppression unit and is connected to the first end of the comparison module. The first terminal of the bidirectional transient voltage suppressor diode is connected to the second terminal of the current limiting resistor, and the second terminal of the bidirectional transient voltage suppressor diode is grounded.

7. The excitation coil insulation detection circuit according to claim 1, characterized in that, The comparison module includes a preset threshold generation unit and a comparison unit; The first output terminal of the preset threshold generation unit is connected to the first pin of the comparison unit, and the second output terminal of the preset threshold generation unit is connected to the second pin of the comparison unit; the preset threshold generation unit is used to provide the comparison unit with the upper limit voltage and the lower limit voltage of the preset threshold. The third and fourth pins of the comparison unit are connected to the second terminal of the protection module; The comparison unit is used to determine that the excitation coil is in a normal state when the second voltage detection signal is less than or equal to the upper limit voltage and the second voltage detection signal is greater than or equal to the lower limit voltage, and outputs a first state signal. When the second voltage detection signal is greater than the upper limit voltage or less than the lower limit voltage, the excitation coil is determined to be in an abnormal state, and a second state signal is output.

8. The excitation coil insulation detection circuit according to claim 7, characterized in that, The preset threshold generation unit includes an upper limit voltage generation subunit and a lower limit voltage generation subunit; The first terminal of the upper limit voltage generation subunit is connected to the positive terminal of the first power supply, the second terminal of the upper limit voltage generation subunit is connected to the first pin of the comparison unit, and the third terminal of the upper limit voltage generation subunit is grounded. The first terminal of the lower limit voltage generation subunit is connected to the negative terminal of the first power supply, the second terminal of the lower limit voltage generation subunit is connected to the second pin of the comparison unit, and the third terminal of the lower limit voltage generation subunit is grounded.

9. The excitation coil insulation detection circuit according to claim 8, characterized in that, The upper limit voltage generation subunit includes a third resistor and a fourth resistor; The first end of the third resistor is connected to the positive terminal of the first power supply, and the second end of the third resistor is connected to the first pin of the comparison unit; the first end of the fourth resistor is connected to the second end of the third resistor, and the second end of the fourth resistor is grounded. The lower limit voltage generation subunit includes a fifth resistor and a sixth resistor; The first end of the fifth resistor is connected to the negative terminal of the first power supply, and the second end of the fifth resistor is connected to the second pin of the comparison unit; the first end of the sixth resistor is connected to the second end of the fifth resistor, and the second end of the sixth resistor is grounded.

10. The excitation coil insulation detection circuit according to claim 7, characterized in that, The excitation coil insulation detection circuit also includes an alarm module; The first end of the alarm module is connected to the second end of the comparison module; the alarm module is used to issue an alarm message when the comparison module outputs the second status signal.

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