Energy-saving and reverse pressure absorption protection system of programmable inductance

Abstract

The application discloses an energy-saving and reverse pressure absorption protection system of a programmed inductor, which comprises a three-phase alternating current power supply, the three-phase alternating current power supply is connected with a current collecting ring, the current collecting ring is connected with an air switch, the air switch is connected with an alternating current input end of a full-controlled bridge thyristor, the positive and negative poles of the full-controlled bridge thyristor are connected with an electromagnet inductive load, and parallel circuits are arranged at the two ends of the electromagnet inductive load. The combined circuit composed of a diode and a contactor or the thyristor is arranged between the positive and negative poles of the main loop output, so that the system power factor of the large inductor during excitation can be effectively improved, the input phase current can be reduced, the temperature rise of the control system can be reduced, the system power efficiency can be improved, the temperature rise of the power device in the system can be reduced, the conduction interference to the power grid can be greatly reduced, and the problem that the high reverse pressure damages the elements in the system due to the poor line contact or the sudden disconnection of the line during the excitation process of the large inductor is eliminated.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic equipment control technology, and more specifically, to an energy-saving and reverse voltage absorption protection system for a programmable inductor. Background Technology

[0002] Currently, the excitation and demagnetization control systems of most large inductors, such as electromagnets, electromagnetic separators, or electromagnetic magnetic separators, almost all use thyristors as power devices to form a three-phase fully controlled rectifier system. The operation of these control systems generally includes excitation and inversion. Excitation involves establishing an excitation current, i.e., converting electrical energy into magnetic field energy. Inversion involves the rapid decay of the excitation current, i.e., converting magnetic field energy back into electrical energy. Some large inductors also include reverse excitation, such as electromagnets, and reverse inversion. Reverse demagnetization refers to establishing a reverse excitation current to create a reverse magnetic field to counteract the residual magnetism of the inductor, which is also a process of converting electrical energy into magnetic field energy. Reverse inversion refers to the rapid decay of the reverse excitation current, which is also a process of converting magnetic field energy back into electrical energy. Excitation is the longest and most crucial process in these operations. The above-mentioned controllable rectifier systems all have the following three defects in the excitation process:

[0003] First: The system has a low power factor on the grid side and low power efficiency. The thyristors, as power devices, form the phase shift angle range of the three-phase fully controlled rectifier system, which is 0-150 degrees Celsius. Since large inductors are inductive loads, negative components begin to appear in the output voltage waveform when the phase shift angle exceeds 60 degrees Celsius. The output voltage waveform in this case is shown in the attached figure. Figure 14 As shown, its output voltage waveform contains both positive and negative voltage components. The period corresponding to the positive voltage waveform is the period during which the grid does work on the inductive load, i.e., the process of converting electrical energy into magnetic field energy. The period corresponding to the negative voltage waveform is the period during which the inductive load does work on the grid, i.e., the process of converting magnetic field energy into electrical energy and feeding it back to the grid. In other words, when the phase shift angle is greater than 60°, the system and the grid are conducting high-frequency round-trip energy transfer. Therefore, the power factor on the grid side of the system begins to drop significantly. When the phase shift angle approaches 150°, the power factor on the grid side of the system approaches zero, so the system's power efficiency is very low.

[0004] Second: It causes significant conducted interference to the power grid. When the phase shift angle is greater than 60 degrees, the high-frequency back-and-forth energy transfer between the system and the power grid will inevitably cause a sharp increase in the high-order harmonic components of the current in each phase of the power grid. Therefore, the conducted interference of the system to the power grid is very large, and this interference increases with the increase of the phase shift angle. This interference can seriously affect the operation of other electrical equipment on the same power grid, and in severe cases, it can cause other electrical equipment on the same power grid to fail to work.

[0005] Third: The reverse voltage absorption capacity is severely insufficient. When this type of control system experiences a sudden circuit break during normal excitation—for example, the overhead crane's sliding contact line suddenly detaches from the slip ring, a fuse on the line suddenly blows, or an air switch suddenly trips due to overload—a sudden change in output current will inevitably occur. Because inductive loads with large inductance store a considerable amount of magnetic field energy during energization (typically, the inductance of an electromagnet is several Henrys, and its rated current is generally on the order of 100 amperes), the magnetic field energy stored after energization is typically on the order of 10,000 joules), such loads will generate very high reverse voltage when the current changes abruptly, typically reaching the order of several kilovolts. Such high reverse voltage is sufficient to damage many components in the control system. Currently, this type of control system almost always uses varistor absorption to absorb reverse voltage; its main circuit schematic is attached. Figure 6 As shown, the limit of reverse voltage absorption by a varistor is generally only a few thousand joules, which is severely insufficient to absorb the magnetic field energy stored in a large inductor. The reverse voltage waveform at the instant the slide wire suddenly separates from the collector ring during operation when the phase shift angle is less than 60 degrees is shown in the attached figure. Figure 12 As shown in the attached figure, when the phase shift angle is greater than 60 degrees and the slip wire suddenly disengages from the collector ring during operation, the reverse voltage waveform is as follows. Figure 16 As shown.

[0006] There is currently no effective solution to the above problems. Summary of the Invention

[0007] In view of the above-mentioned technical problems in related technologies, the present invention proposes an energy-saving and reverse voltage absorption protection system for a programmable inductor, which can overcome the above-mentioned shortcomings of the prior art.

[0008] To achieve the above-mentioned technical objectives, the technical solution of the present invention is implemented as follows:

[0009] An energy-saving and reverse voltage absorption protection system for a programmable inductor includes a three-phase AC power supply, which is connected to a slip ring. The slip ring is electrically connected to a circuit breaker. The circuit breaker is electrically connected to the AC input terminal of a fully controlled bridge thyristor. The positive and negative terminals of the fully controlled bridge thyristor are both electrically connected to an electromagnet inductive load. A parallel circuit is provided across the two ends of the electromagnet inductive load. The parallel circuit is a combination of a thyristor G6 or a diode and a contactor for reverse voltage absorption.

[0010] Furthermore, the three-phase AC power supply includes phase A, phase B, and phase C.

[0011] Furthermore, the fully controlled bridge thyristors include fully controlled bridge thyristor G0, fully controlled bridge thyristor G1, fully controlled bridge thyristor G2, fully controlled bridge thyristor G3, fully controlled bridge thyristor G4 and fully controlled bridge thyristor G5.

[0012] Furthermore, the contactor is a normally open contactor or a normally closed contactor.

[0013] Furthermore, the contactor is connected in series with the positive or negative terminal of the diode.

[0014] Furthermore, the contactor is communicatively connected to a program device or peripheral device.

[0015] Furthermore, the thyristor G6 for reverse voltage absorption is communicatively connected to the program device or peripheral device.

[0016] The beneficial effects of this invention are as follows: By adding a combined circuit of diodes and contactors or a thyristor between the positive and negative terminals of the main circuit output, this invention effectively improves the power factor on the grid side of large inductors such as electromagnets, electromagnetic separators, or electromagnetic magnetic separators during excitation; reduces input phase current; reduces the temperature rise of the control system; improves system power efficiency; reduces the temperature rise of power devices in the system; significantly reduces conducted interference to the power grid; and improves the absorption capacity of protection systems that rely on varistors to absorb reverse voltage. This reliably ensures the safe operation of the equipment and eliminates the problem of high reverse voltage damaging system components due to poor line contact or sudden line disconnection during the excitation process of large inductors such as electromagnets, electromagnetic separators, or electromagnetic magnetic separators. The system is safe, reliable, and highly stable. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the 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 This is a schematic diagram of the energy-saving and back pressure absorption protection system according to an embodiment of the present invention. Figure 1 ;

[0019] Figure 2 This is a schematic diagram of the energy-saving and back pressure absorption protection system according to an embodiment of the present invention. Figure 2 ;

[0020] Figure 3 This is a schematic diagram of the energy-saving and back pressure absorption protection system according to an embodiment of the present invention. Figure 3 ;

[0021] Figure 4 This is a schematic diagram of the energy-saving and back pressure absorption protection system according to an embodiment of the present invention. Figure 4 ;

[0022] Figure 5 This is a schematic diagram of the energy-saving and back pressure absorption protection system according to an embodiment of the present invention. Figure 5 ;

[0023] Figure 6 This is a schematic diagram of the excitation main circuit structure of a conventional electromagnet or other inductive load according to an embodiment of the present invention;

[0024] Figure 7 The energy-saving and reverse voltage absorption protection system according to the embodiment of the present invention uses a combination circuit of diodes and contactors to form an energy-saving and reverse voltage absorption protection circuit system. When the phase shift angle of the fully controlled bridge is greater than 60 degrees and the output is positive, the current path is as follows:

[0025] Figure 8 The energy-saving and reverse voltage absorption protection system according to the embodiment of the present invention uses a combination circuit of diodes and contactors to form an energy-saving and reverse voltage absorption protection circuit system. When the phase shift angle of the fully controlled bridge is greater than 60 degrees, the negative voltage component is eliminated during the period of the traditional output negative voltage component (including the instant when the slide wire and the collector ring are disengaged).

[0026] Figure 9 This refers to the current path during the output positive voltage period of the energy-saving and reverse voltage absorption protection system of the present invention, which uses thyristors to construct the energy-saving and reverse voltage absorption protection circuit. When the phase shift angle of the fully controlled bridge is greater than 60 degrees.

[0027] Figure 10 This refers to the current path of the energy-saving and reverse voltage absorption protection system according to the embodiments of the present invention, which uses thyristors to construct the energy-saving and reverse voltage absorption protection circuit. When the phase shift angle of the fully controlled bridge is greater than 60 degrees and the negative voltage component is eliminated during the output negative voltage component period (including the instant when the slide wire and the collector ring are disengaged).

[0028] Figure 11 This is the output voltage waveform of the energy-saving and reverse voltage absorption protection system according to an embodiment of the present invention when the phase shift angle is less than 60 degrees;

[0029] Figure 12 This is the output voltage waveform of the conventional electromagnet main circuit using a rectifier system with absorption by a varistor according to an embodiment of the present invention, when the phase shift angle is less than 60 degrees and the slide wire and the collector ring suddenly disengage;

[0030] Figure 13 This is the output voltage waveform of the rectifier system of the energy-saving and back-voltage absorption protection system according to the embodiment of the present invention when the phase shift angle is less than 60 degrees and the slide wire and the collector ring suddenly disengage;

[0031] Figure 14 The output voltage waveform of the conventional electromagnet main circuit with varistor absorption according to the embodiment of the present invention has a phase shift angle greater than 60 degrees.

[0032] Figure 15 This is the output voltage waveform of the rectifier system using the absorption technology of this invention in the energy-saving and reverse voltage absorption protection system according to an embodiment of the present invention when the phase shift angle is greater than 60 degrees;

[0033] Figure 16 This is the output voltage waveform of the conventional electromagnet main circuit using a rectifier system with absorption by a varistor according to an embodiment of the present invention, when the phase shift angle is greater than 60 degrees and the slide wire and the collector ring suddenly disengage;

[0034] Figure 17 This is the output voltage waveform of the rectifier system of the energy-saving and back-voltage absorption protection system according to the embodiment of the present invention when the phase shift angle is greater than 60 degrees and the slide wire and the collector ring suddenly disengage;

[0035] In the diagram: 1. Phase A, 2. Phase B, 3. Phase C, 4. Slip ring, 5. Circuit breaker, 6. Fully controlled bridge thyristor, 7. Diode, 8. Normally open contactor, 9. Electromagnetic inductive load, 10. Three-phase AC power supply, 11. Fully controlled bridge thyristor G0, 12. Fully controlled bridge thyristor G1, 13. Fully controlled bridge thyristor G2, 14. Fully controlled bridge thyristor G3, 15. Fully controlled bridge thyristor G4, 16. Fully controlled bridge thyristor G5, 17. Thyristor for reverse voltage absorption G6, 18. Normally closed contactor, 19. Varistor. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0037] like Figure 1-5 As shown in the figure, an energy-saving and reverse voltage absorption protection system for a programmable inductor according to an embodiment of the present invention includes a three-phase AC power supply 10, the three-phase AC power supply 10 being connected to a slip ring 4, the slip ring 4 being electrically connected to an air circuit breaker 5, the air circuit breaker 5 being electrically connected to the AC input terminal of a fully controlled bridge thyristor 6, the positive and negative terminals of the fully controlled bridge thyristor 6 being electrically connected to an inductive load 9 such as an electromagnet, and a parallel circuit being provided at both ends of the inductive load 9 such as the electromagnet, the parallel circuit being a combination of a thyristor G6 17 or a diode 7 for reverse voltage absorption and a contactor.

[0038] In this embodiment, the three-phase AC power supply 10 includes phase A 1, phase B 2, and phase C 3. The fully controlled bridge thyristor 6 includes fully controlled bridge thyristors G0 11, G1 12, G2 13, G3 14, G4 15, and G5 16.

[0039] In this embodiment, the contactor is a normally open contactor 8 or a normally closed contactor 18. The contactor is connected in series with the positive or negative terminal of the diode 7. The contactor is communicatively connected to the program device or peripheral device. The reverse voltage absorption thyristor G617 is communicatively connected to the program device or peripheral device.

[0040] To facilitate understanding of the above technical solutions of the present invention, the following detailed description of the above technical solutions of the present invention will be provided through specific usage methods.

[0041] In practical application, according to the energy-saving and reverse voltage absorption protection system of the programmable inductor described in this invention, a combined circuit consisting of diodes and contactors is added between the positive and negative terminals of the main circuit output. Their orientation and connection method are as follows: Figure 1-4 As shown, or a thyristor can be added between the positive and negative terminals of the main circuit output, with its direction as shown. Figure 5 As shown.

[0042] The effective activation and deactivation of diodes can be controlled by controlling the contactor coil through a program or peripheral device, or the conduction and cutoff of thyristors can be controlled by triggering the thyristor's trigger electrode through a program or peripheral device.

[0043] The activation / deactivation of the energy-saving and reverse voltage absorption protection circuit is controlled by the program and peripherals. The system activates the energy-saving and reverse voltage absorption protection circuit during idle and excitation processes. The system deactivates the energy-saving and reverse voltage absorption protection circuit during inversion, reverse excitation, and reverse inversion processes.

[0044] There are several situations when using it:

[0045] 1. In systems that use a combination of diodes and contactors to form an energy-saving and reverse voltage absorption protection circuit, during idle or energizing periods, the contactor contacts are closed via a program or external device, effectively connecting the diodes to the main output circuit. When the phase shift angle of the fully controlled bridge is greater than 60 degrees, its output voltage waveform is shown in the attached figure. Figure 15 As shown, the negative voltage component in the waveform has been eliminated; the output voltage waveform at the instant when the phase shift angle of the fully controlled bridge is greater than 60 degrees and the slip wire suddenly disengages from the collector ring is shown in the attached figure. Figure 17As shown, the negative voltage and high reverse voltage components in the waveform are eliminated; if a system using a combination circuit of diodes and contactors to form an energy-saving and reverse voltage absorption protection circuit is used, the current path during the positive voltage period of the output when the phase shift angle of the fully controlled bridge is greater than 60 degrees is as shown in the attached figure. Figure 7 As shown in the figure. The current path of this type of system during the period when the phase shift angle of the fully controlled bridge is greater than 60 degrees and the negative output voltage component is eliminated (including the instant the slide wire and collector ring disengage), is as follows: Figure 8 As shown, the system did not transmit energy back and forth with the power grid during this period; the output voltage waveform at the instant the slip wire and collector ring suddenly disengaged when the phase shift angle of the fully controlled bridge was less than 60 degrees is shown in the attached figure. Figure 13 As shown.

[0046] 2. In systems employing thyristors to construct energy-saving and reverse-voltage absorption protection circuits, a constant DC current is supplied to the trigger electrode of the thyristor during idle or energizing periods via a program or external device to ensure reliable conduction of the thyristor. When the phase shift angle of the fully controlled bridge is greater than 60 degrees, its output voltage waveform is shown in the attached figure. Figure 15 As shown, the negative voltage component in the waveform has been eliminated; the output voltage waveform at the instant when the phase shift angle of the fully controlled bridge is greater than 60 degrees and the slip wire suddenly disengages from the collector ring is shown in the attached figure. Figure 17 As shown, the negative voltage and high reverse voltage components in the waveform are eliminated; if a thyristor is used to construct an energy-saving and reverse voltage absorption protection circuit, the current path during the output positive voltage period when the phase shift angle of the fully controlled bridge is greater than 60 degrees is shown in the attached figure. Figure 9 As shown in the figure. In this type of system, when the phase shift angle of the fully controlled bridge is greater than 60 degrees and the negative voltage component is eliminated (including the instant the slip wire and collector ring disengage), the current path is as follows: Figure 10 As shown, the system did not transmit energy back and forth with the power grid during this period; the output voltage waveform at the instant the slip wire and collector ring suddenly disengaged when the phase shift angle of the fully controlled bridge was less than 60 degrees is shown in the attached figure. Figure 13 As shown.

[0047] 3. For systems that use a combination of diodes and contactors to form an energy-saving and reverse voltage absorption protection circuit, before performing inversion, first determine whether the phase shift angle is greater than 60 degrees. If the phase shift angle is greater than 60 degrees, adjust the phase shift angle to less than 60 degrees and maintain it for a period of time, generally 0.1 seconds, to ensure that the current in the diode is reduced to zero. Then maintain the phase shift angle less than 60 degrees for a period of time, generally 0.15 seconds, to ensure that there is enough time to disconnect the contactor. After that, start performing inversion, reverse excitation, and reverse inversion actions. After all the actions of one working cycle are completed, reclose the contactor combined with the diode.

[0048] 4. If the system uses thyristors to form an energy-saving and reverse voltage absorption protection circuit, the power supply to the trigger electrode of the thyristor shall be stopped before the inverter is executed. After a period of time (usually 0.05 seconds), the inverter, reverse excitation and reverse phase inverter operations shall be started. After all the operations of one working cycle are completed, the power supply to the trigger electrode of the thyristor shall be restored.

[0049] The present invention can achieve the following objectives: improve the power factor of the power grid side of the system and improve the power consumption efficiency of the system; reduce the conducted interference of the system to the power grid; and greatly enhance the system's ability to absorb reverse voltage (there is no upper limit to the absorption capacity).

[0050] In summary, by employing the technical solution described above, adding a combined circuit of diodes and contactors or a thyristor between the positive and negative terminals of the main circuit output can effectively improve the grid-side power factor of large inductors such as electromagnets, electromagnetic separators, or electromagnetic magnetic separators during excitation; reduce input phase current; reduce the temperature rise of the control system; improve system power efficiency; reduce the temperature rise of power devices in the system; significantly reduce conducted interference to the power grid; improve the absorption capacity of protection systems that rely on varistors to absorb reverse voltage; reliably ensure the safe operation of the equipment; and eliminate the problem of high reverse voltage damaging system components due to poor line contact or sudden line disconnection during the excitation process of large inductors such as electromagnets, electromagnetic separators, or electromagnetic magnetic separators. This system is safe, reliable, and highly stable.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An energy-saving and reverse voltage absorption protection system for a programmable inductor, characterized in that, Includes a three-phase AC power supply (10), the three-phase AC power supply (10) is connected to a slip ring (4), the slip ring (4) is electrically connected to a circuit breaker (5), the circuit breaker (5) is electrically connected to the AC input terminal of a fully controlled bridge thyristor (6), the positive and negative terminals of the fully controlled bridge thyristor (6) are both electrically connected to an electromagnet inductive load (9), and a parallel circuit is provided at both ends of the electromagnet inductive load (9), the parallel circuit is a combination of a reverse voltage absorption thyristor G6 (17) or a diode (7) and a contactor; The parallel circuit is used to eliminate the negative voltage component in the voltage waveform across the electromagnet inductive load (9) when the phase shift angle of the fully controlled bridge thyristor (6) is greater than 60 degrees.

2. The energy-saving and back pressure absorption protection system according to claim 1, characterized in that, The three-phase AC power supply (10) includes phase A (1), phase B (2) and phase C (3).

3. The energy-saving and back pressure absorption protection system according to claim 1, characterized in that, The fully controlled bridge thyristor (6) includes fully controlled bridge thyristor G0 (11), fully controlled bridge thyristor G1 (12), fully controlled bridge thyristor G2 (13), fully controlled bridge thyristor G3 (14), fully controlled bridge thyristor G4 (15) and fully controlled bridge thyristor G5 (16).

4. The energy-saving and back pressure absorption protection system according to claim 1, characterized in that, The contactor is a normally open contactor (8) or a normally closed contactor (18).

5. The energy-saving and back pressure absorption protection system according to claim 1, characterized in that, The contactor is connected in series with the positive or negative terminal of the diode (7).

6. The energy-saving and back pressure absorption protection system according to claim 1, characterized in that, The coil leads of the contactor are connected to the program device or peripheral device for communication.

7. The energy-saving and back pressure absorption protection system according to claim 1, characterized in that, The cathode of the reverse voltage absorption thyristor G6 (17) is connected to the positive output terminal of the fully controlled bridge thyristor, the anode of the reverse voltage absorption thyristor G6 (17) is connected to the negative output terminal of the fully controlled bridge thyristor, and the trigger electrode of the reverse voltage absorption thyristor G6 (17) is connected to the program device or peripheral device for communication.

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