CN114070065B - Superconducting magnet periodic lifting magnetic circuit and control method thereof - Google Patents
Superconducting magnet periodic lifting magnetic circuit and control method thereof Download PDFInfo
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- CN114070065B CN114070065B CN202111505811.3A CN202111505811A CN114070065B CN 114070065 B CN114070065 B CN 114070065B CN 202111505811 A CN202111505811 A CN 202111505811A CN 114070065 B CN114070065 B CN 114070065B
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- 238000000034 method Methods 0.000 title claims abstract description 22
- 230000000737 periodic effect Effects 0.000 title claims abstract description 14
- 239000003990 capacitor Substances 0.000 claims abstract description 64
- 238000004146 energy storage Methods 0.000 claims description 16
- 230000005284 excitation Effects 0.000 claims description 8
- 230000005684 electric field Effects 0.000 claims description 4
- 239000006148 magnetic separator Substances 0.000 abstract description 25
- 239000013589 supplement Substances 0.000 abstract description 4
- 230000005611 electricity Effects 0.000 abstract description 2
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 239000002002 slurry Substances 0.000 description 10
- 230000008569 process Effects 0.000 description 8
- 230000008901 benefit Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 230000005389 magnetism Effects 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000002441 reversible effect Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000005347 demagnetization Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C1/00—Magnetic separation
- B03C1/02—Magnetic separation acting directly on the substance being separated
- B03C1/025—High gradient magnetic separators
- B03C1/031—Component parts; Auxiliary operations
- B03C1/033—Component parts; Auxiliary operations characterised by the magnetic circuit
- B03C1/0335—Component parts; Auxiliary operations characterised by the magnetic circuit using coils
- B03C1/0337—Component parts; Auxiliary operations characterised by the magnetic circuit using coils superconductive
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F6/00—Superconducting magnets; Superconducting coils
- H01F6/006—Supplying energising or de-energising current; Flux pumps
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Containers, Films, And Cooling For Superconductive Devices (AREA)
Abstract
The invention discloses a superconducting magnet periodic lifting magnetic circuit and a control method thereof, wherein the superconducting magnet periodic lifting magnetic circuit comprises 2 power switches, 3 power diodes, 1 capacitor and 1 programmable direct current power supply, wherein the 2 power switches and the 2 power diodes form four bridge arms of an H-shaped circuit, a superconducting coil is positioned in the center of the H-shaped circuit, and the four bridge arms of the H-shaped circuit are arranged in a mode that current can only flow through the superconducting coil in one direction; the capacitor is connected with the H-shaped circuit in parallel, and the direct current power supply is connected with the H-shaped circuit after being connected with the 1 power diode in series to form a power supply branch. The present invention is provided with: 1. after the energy is saved and the current control enters a normal working time sequence, the direct current power supply for taking electricity from the power grid only needs to supplement a small amount of energy consumed by the circuit, so that the magnetic separator is converted into energy-saving equipment from high-energy-consumption equipment; 2. the efficiency is high, and the working efficiency of the magnetic separator is maximized while the stability of the superconducting coil is considered; 3. reliable, there is not the risk that homonymy bridge arm switches on simultaneously.
Description
Technical Field
The invention belongs to the technical field of electric energy conversion, and particularly relates to a superconducting magnet periodic lifting magnetic circuit for an electromagnetic slurry magnetic separator and a control method thereof.
Background
The magnetic system is a key functional component of the electromagnetic slurry magnetic separator and consists of a coil, iron armors and magnetic poles. The basic principle of the electromagnetic slurry magnetic separator is as follows: loading current to the coil, so that a magnetic field corresponding to the current fills the space where the magnetic collecting medium is located, and under the action of the magnetic field force, the magnetic ore particles are captured by the magnetic collecting medium; when the capturing amount is close to saturation, the coil current is reduced to zero, the magnetic field force is also disappeared, and the magnetic ore particles leave the magnetism collecting medium and the space where the magnetism collecting medium and the space are located under the flushing of clear water or gas or a mixture of the clear water and the gas. The two processes are operated alternately, so that continuous production of separating magnetic minerals from non-magnetic minerals is realized. It can be seen that it is necessary that the duration of the zero magnetic field and the specified magnetic field is determined by the production process; the time spent for the up-and down-magnetization is not necessary for the production process, and they reduce the working efficiency of the magnetic separator.
Since the resistivity of a superconducting conductor is zero and the upper current density limit is high, superconducting coils have two distinct benefits compared to normal coils: first, the magnetic field which is several times that of the normal coil can be provided in the same volume of space for a long time; second, there is no power loss due to resistance at all. The former can be used for separating ore particles with weaker magnetism, and the application range of the magnetic separator is expanded; the latter has obvious energy saving advantages.
The energy in the normally conductive coil is divided into two parts, one part is stored in the inductance of the normally conductive coil in a magnetic energy mode, and the other part is dissipated on the resistance of the normally conductive coil in a Joule heat mode. The former is useful energy for generating a magnetic field, and its proportion determines the energy utilization efficiency of the magnetic separator. The mode of lifting the magnetic field with highest energy utilization efficiency at present is as follows: the control circuit is alternately operated in a rectifying and inverting mode by using the power switching device, so that energy is alternately taken from and fed to the power grid. In order to save equipment cost, a common conductive magnetic slurry magnetic separator often uses a simple rectifying inverter circuit. The high frequency component caused by the simple inversion makes the power fed back to the grid low quality and even considered as pollution to the grid, and is therefore limited. The practical effect of this control is not ideal. Another more direct way of demagnetizing is to use an external resistor to convert the magnetic energy in the coil into heat. So that all of the energy in the normally conductive coil is eventually dissipated by the external resistor.
The magnetic energy density is proportional to the square of the magnetic field strength, and the magnetic energy in a superconducting coil is usually much larger than that in a normally conductive coil in order to generate a stronger magnetic field. If the lifting magnetic mode is adopted, the superconducting electromagnetic slurry magnetic separator is more energy-consuming than the normal-conduction magnetic slurry magnetic separator.
Disclosure of Invention
The invention aims to provide a superconducting magnet periodic lifting magnetic circuit and a control method thereof, so that a superconducting electromagnetic slurry magnetic separator alternately works in a zero magnetic field and a designated magnetic field, and meanwhile, the advantage of non-resistance power loss of a superconducting coil is exerted, and the purposes of saving energy and not polluting a power grid are achieved.
The invention is realized by the following technical scheme:
The superconducting magnet periodic lifting magnetic circuit comprises 2 power switches, 3 power diodes, 1 capacitor and 1 programmable direct current power supply, wherein the 2 power switches and the 2 power diodes form four bridge arms of an H-shaped circuit, a superconducting coil is positioned in the center of the H-shaped circuit, and the four bridge arms of the H-shaped circuit are arranged in a mode that current can only flow through the superconducting coil in one direction; the capacitor is connected with the H-shaped circuit in parallel, and the direct current power supply is connected with the H-shaped circuit after being connected with the 1 power diode in series to form a power supply branch.
Preferably, the power switch is fully controlled due to the need to cut off large currents during the step-up process.
Preferably, the direct current power supply allows automatic switching between two modes of operation, a current source and a voltage source, the anode of the power diode in the power supply branch being connected to the positive pole of the direct current power supply.
The circuit formed by connecting the capacitor in parallel with the H-shaped circuit in the circuit is also used for a superconducting energy storage system in the power industry, and the essential difference of the circuit is that the effect of the capacitor is different. In a superconducting energy storage system, a superconducting coil is the only energy storage element, and when energy flows between a power grid and the superconducting coil, a capacitor is required to stabilize fluctuation of direct current voltage, so that a filtering effect is exerted. In the invention, the capacitor and the superconducting coil are both energy storage elements and have approximately the same energy storage energy. When the magnetic separator requires the superconducting coil to operate in a zero magnetic field, energy is transferred to the capacitor for temporary storage; and when the magnetic separator requires the superconducting coils to operate at a specified magnetic field, energy is re-transferred to the superconducting coils. This results in two distinct parameter design methods and control methods.
The invention also provides a control method of the superconducting magnet periodic lifting magnetic circuit, which comprises the following steps: when the capacitor voltage is smaller than the preset voltage of the direct current power supply, the power diode of the power supply branch is conducted, the two power switches of the bridge arm at the opposite side of the H-shaped circuit are controlled to be conducted, and the direct current power supply works in a current source mode to boost or keep a magnetic field for the superconducting coil; when the voltage of the capacitor is larger than the preset voltage of the direct current power supply, the power diode of the power supply branch is cut off, the current of the power supply branch is reduced to zero, the power supply works in a voltage source mode, and the capacitor is used for exciting the superconducting coil. In an initial state that the capacitor voltage is zero and the current of the superconducting coil is zero, controlling the two power switches of a bridge arm at the opposite side of the H-shaped circuit to be conducted, and loading current to the superconducting coil by a direct current power supply for excitation; the following three control logics are then sequentially executed in cycles:
When the specified magnetic field reaches the specified duration, the control logic I controls the two power switches of the opposite side bridge arm of the H-shaped circuit to be turned off, so that the power diodes of the other two bridge arms are turned on because the current of the superconducting coil cannot be suddenly changed, the superconducting coil charges the capacitor, most of magnetic energy in the superconducting coil is converted into electric field energy in the capacitor, and the electric field energy is consumed in the switching device and the connecting circuit in a small part;
When the capacitor voltage reaches the vicinity of the maximum value or the current of the superconducting coil is reduced to be close to zero, the control logic II controls one power switch of the H-shaped circuit to be conducted, so that the current of the superconducting coil is reliably reduced to zero; in order to fully absorb energy from the superconducting coil, the maximum value of the capacitor voltage is far higher than the preset voltage of the direct current power supply;
The control logic III controls the two power switches of the opposite-side bridge arm of the H-shaped circuit to be conducted when the zero magnetic field reaches the specified duration, and discharges the capacitor to the superconducting coil when the capacitor voltage is higher than the direct-current power supply voltage; when the capacitor voltage is lower than the DC power supply voltage, the power diode in the power supply branch is conducted, and the DC power supply continues to supply current to the superconducting coil until a preset current value is reached, and meanwhile, a specified magnetic field is reached.
Preferably, the excitation and demagnetization times of the superconducting coil are more than 10 seconds, and the specified voltage of the capacitor is less than 1 kilovolt.
Preferably, the second control logic is preferably conducted with a power switch of a bridge arm connected with the negative electrode of the direct current power supply.
The beneficial effects of the invention are as follows:
The superconducting magnet periodic lifting magnetic circuit has ingenious structure and strong practicability, and particularly has the following advantages:
1. Energy saving. After the current control enters the normal operation sequence (as in the previous control logic one to control logic three), most of the energy is converted between the superconducting coil and the capacitor, and a small part of the energy is lost in the circuit itself. The direct current power supply for taking electricity from the power grid only needs to supplement a small amount of energy, so that the magnetic separator is converted into energy-saving equipment from high-energy-consumption equipment.
2. High efficiency. The magnetic separator has the advantages that the magnetic rising time and the magnetic falling time of the coil are adjusted by selecting different capacitance capacities and the highest charging voltage, so that the working efficiency of the magnetic separator is maximized while the stability of the superconducting coil is considered.
3. Reliable. The circuit adopts a mode of combining active control (by using a fully-controlled power switch device) and passive control (by using a power diode), so that the risk of simultaneous conduction of the same-side bridge arm is ensured in principle, and the power switch device always has a smaller voltage rising rate when being switched in a conducting state and a switching state, thereby ensuring the long-term reliability of the superconducting coil and the control circuit.
Drawings
For ease of illustration, the invention is described in detail by the following specific examples and figures.
FIG. 1 is a schematic diagram of a lifting magnetic circuit of a superconducting electromagnetic slurry magnetic separator;
FIG. 2 illustrates the path and direction of current flow in the initial excitation process circuit;
FIG. 3 shows the path and flow direction of current in the superconducting coil to capacitor demagnetizing process circuit;
FIG. 4a illustrates the current path and flow direction in the superconducting coil rapid demagnetizing process circuit under the conduction condition of the lower bridge arm power switch;
Fig. 4b illustrates the path and flow direction of current in the superconducting coil rapid demagnetizing process circuit under the conduction condition of the upper bridge arm power switch;
FIG. 5 is a schematic diagram showing the path and direction of current flow in a circuit for energizing a coil with a capacitor;
FIG. 6 is a schematic diagram showing the path and direction of current flow in the circuit during excitation of the coil by the DC power supply;
FIG. 7 is a graph showing typical coil current curves for a superconducting electromagnetic slurry magnetic separator.
Detailed Description
As shown in fig. 1, the superconducting magnet periodic lifting magnetic circuit comprises 2 power switches, 3 power diodes, 1 capacitor and 1 programmable direct current power supply, wherein the 2 power switches and the 2 power diodes form four bridge arms of an H-shaped circuit, a superconducting coil is positioned in the center of the H-shaped circuit, and the four bridge arms of the H-shaped circuit are arranged in a manner that current can only flow through the superconducting coil in one direction; the capacitor is connected with the H-shaped circuit in parallel, and the direct current power supply is connected with the H-shaped circuit after being connected with the 1 power diode in series to form a power supply branch.
The power switch is fully controlled due to the ability to cut off large currents during the demagnetizing process.
The direct current power supply allows automatic switching between two working modes of a current source and a voltage source, and the anode of a power diode in the power supply branch is connected with the anode of the direct current power supply.
The circuit formed by connecting the capacitor in parallel with the H-shaped circuit in the circuit is also used for a superconducting energy storage system in the power industry, and the essential difference of the circuit is that the effect of the capacitor is different. In a superconducting energy storage system, a superconducting coil is the only energy storage element, and when energy flows between a power grid and the superconducting coil, a capacitor is required to stabilize fluctuation of direct current voltage, so that a filtering effect is exerted. In the invention, the capacitor and the superconducting coil are both energy storage elements and have approximately the same energy storage energy. When the magnetic separator requires the superconducting coil to operate in a zero magnetic field, energy is transferred to the capacitor for temporary storage; and when the magnetic separator requires the superconducting coils to operate at a specified magnetic field, energy is re-transferred to the superconducting coils. This results in two distinct parameter design methods and control methods.
The invention also provides a control method of the superconducting magnet periodic lifting magnetic circuit, which comprises the following steps: when the capacitor voltage is smaller than the preset voltage of the direct current power supply, the power diode of the power supply branch is conducted, the two power switches of the bridge arm at the opposite side of the H-shaped circuit are controlled to be conducted, and the direct current power supply works in a current source mode to boost or keep a magnetic field for the superconducting coil; when the capacitor voltage is larger than the preset voltage of the direct-current power supply, the power diode of the power supply branch circuit is cut off, the current of the power supply branch circuit is reduced to zero, and the power supply works in a voltage source mode; in an initial state that the capacitor voltage is zero and the current of the superconducting coil is zero, controlling the two power switches of a bridge arm at the opposite side of the H-shaped circuit to be conducted, and loading current to the superconducting coil by a direct current power supply for excitation; the following three control logics are then sequentially executed in cycles:
When the specified magnetic field reaches the specified duration, the control logic I controls the two power switches of the opposite side bridge arm of the H-shaped circuit to be turned off, and the power diodes of the other two bridge arms are turned on because the current of the superconducting coil cannot be suddenly changed, the superconducting coil charges the capacitor, and most of magnetic energy in the superconducting coil is converted into electric field energy in the capacitor;
When the capacitor voltage reaches the vicinity of the maximum value or the current of the superconducting coil is reduced to be close to zero, the control logic II controls one power switch of the H-shaped circuit to be conducted, so that the current of the superconducting coil is reliably reduced to zero; in order to fully absorb energy from the superconducting coil, the maximum value of the capacitor voltage is far higher than the preset voltage of the direct current power supply;
The control logic III controls the conduction of the two power switches of the opposite-side bridge arm of the H-shaped circuit when the zero magnetic field reaches the appointed duration, and discharges the capacitor to the superconducting coil when the voltage of the capacitor is higher than the voltage of the direct-current power supply; when the capacitor voltage is lower than the DC power supply voltage, the power diode in the power supply branch is conducted, and the DC power supply continues to supply current to the superconducting coil until a preset current value is reached, and meanwhile, a specified magnetic field is reached.
Generally, the excitation and demagnetization time of the superconducting coil is more than 10 seconds within the safety allowable range of the equipment, and the designated voltage of the capacitor is less than 1 kilovolt.
The second control logic is preferably conducted with a power switch of a bridge arm connected with the negative electrode of the direct current power supply.
Examples
Referring to fig. 1, the lifting magnetic circuit of the superconducting electromagnetic slurry magnetic separator comprises 2 full-control power switches, 3 power diodes, 1 energy storage capacitor and 1 programmable direct current power supply. The 2 power switches and the 2 power diodes form four bridge arms of the H-shaped circuit. The power switching device is a fully controlled, preferably an IGBT, represented in the figures by IGBT circuit symbols. R1 and R2 respectively represent the resistances of all cables and joints in the electrical connection between the two leads of the superconducting coil and the points c and d of the circuit.
For a better understanding of the invention and to distinguish it from the prior art, the mode of operation of the circuit is divided into 7 different states in the embodiment shown in fig. 1, 5 of which are shown in fig. 2 to 6, respectively. The flow path and direction of the current are the key basis for distinguishing these states. The following description of 7 states with reference to fig. 2 to 6 follows:
State 1: referring to fig. 2, the current of the inductor L (i.e., superconducting coil) and the voltage of the capacitor C in the initial time circuit are zero. The power switching elements Q1 and Q2 are controlled to be turned on, the power diodes D1 and D2 are turned off due to the reverse voltage, and the direct current power supply PS takes power from the power grid to excite the superconducting coil L to a specified current and charge the capacitor to be close to the power supply voltage, respectively.
State 2: the power switching elements Q1 and Q2 are kept on, and the direct current power supply PS continues to supply a current of a prescribed magnitude to the superconducting coil. At the moment, the magnetic separator works under a specified magnetic field approximately proportional to the specified current, and magnetic ore particles in the ore pulp are adsorbed in the magnetism collecting medium space.
State 3: referring to fig. 3, when a designated magnetic field is continued for a designated time, the power switching elements Q1 and Q2 are controlled to be turned off. The current in the superconducting coil cannot change immediately, the power diodes D1 and D2 are forced to conduct, the superconducting coil charges the storage capacitor, and the current continuously decays. Depending on the characteristics of the lc series circuit, the current decay rate will be continuously reduced.
State 4-1: referring to fig. 4a, the control power switching element Q2 is turned on when the coil current decays to some small amount, and the coil current will decay rapidly to zero. The current and the voltage of the capacitive branch between the points a and b in the circuit, the current of the coil branch between the points c and d and the voltage between any two points can be used as control signals for triggering the conduction of the Q2.
State 4-2: equivalently to state 4-1, referring to fig. 4b, controlling the power switching element Q1 to turn on also enables the coil current to decay rapidly to zero.
State 5: the coil current remains zero with the power switching element Q1 or Q2 on and the other power switching element off. At this time, the magnetic separator works under the zero magnetic field, and the magnetic ore particles losing the magnetic field force are carried by the gas, liquid or the gas-liquid mixed fluid and discharged out of the magnetic collecting medium space.
State 6: referring to fig. 5, when the zero magnetic field is sustained for a specified time, the power switching elements Q1 and Q2 are controlled to be turned on. Since the energy storage capacitor voltage is much higher than the dc supply voltage, the power diode D3 is turned off and the power diodes D1 and D2 are turned off by receiving the reverse voltage. The energy storage capacitor is a superconducting coil excitation.
State 7: referring to fig. 6, the power switching elements Q1 and Q2 are kept on, and when the voltage of the energy storage capacitor is lower than the voltage of the dc power supply, the power diode D3 is turned on, and the dc power supply continues to excite the superconducting coil.
The 7 states are sequentially switched from 1 to 7 and repeatedly circulated.
The term "specified" in the above text means specified by the beneficiation process.
Referring to fig. 7, where arabic numerals aligned along a time axis (horizontal axis) correspond to the above 7 states one by one, adjacent states are separated by a dash-dot line, Δi 1 represents a small amount of current in the state 4-1 or state 4-2 transition condition, and I op represents a current value reached at the end of exciting the coil by the storage capacitor. Δi 2 represents the current increment by which the coil is energized by the dc power supply to supplement the lost energy. As can be seen, the duration of state 7 should be greater than the time that the dc power supply supplements the coil with current increments, and the magnetic field strength corresponding to I op should be greater than or equal to the specified value. From state 3 onwards the magnetic separator enters a normal working cycle, wherein state 5 corresponds to a zero magnetic field and state 7 corresponds to a magnetic field above a specified value.
Referring to fig. 1, the branches between any two nodes in the circuit are processed in series-parallel connection, but the equivalent result does not change the modification of the functions of the branches, and the equivalent result is still within the protection scope of the patent. For example using a series or parallel connection of several capacitors instead of a capacitive branch.
Referring to fig. 1, for the power switch element, whether the reverse power diode is connected in parallel or not, whether the buffer circuit is configured or not, the on and off functions of the element are not changed, and the power switch element is still within the protection scope of the patent.
The foregoing is merely illustrative of specific embodiments of the present invention, and the scope of the invention is not limited thereto, but any changes or substitutions that do not undergo the inventive effort should be construed as falling within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.
Claims (2)
1. The control method of the superconducting magnet periodic lifting magnetic circuit is characterized by comprising 2 power switches, 3 power diodes, 1 capacitor and 1 programmable direct current power supply, wherein the 2 power switches and the 2 power diodes form four bridge arms of an H-shaped circuit, a superconducting coil is positioned in the center of the H-shaped circuit, and the four bridge arms of the H-shaped circuit are arranged in a mode that current can only flow through the superconducting coil in one direction; the capacitor is connected with the H-shaped circuit in parallel, and the direct current power supply is connected with the H-shaped circuit after being connected with the 1 power diode in series to form a power supply branch; the power switch is a full-control power switch; the direct current power supply is a direct current power supply which allows automatic switching between two working modes of a current source and a voltage source, and the anode of a power diode in the power supply branch is connected with the anode of the direct current power supply; the capacitor and the superconducting coil are both energy storage elements and have approximately the same energy storage energy, and the control method of the superconducting magnet periodic lifting magnetic circuit comprises the following steps: when the capacitor voltage is smaller than the preset voltage of the direct current power supply, the power diode of the power supply branch is conducted, the two power switches of the bridge arm at the opposite side of the H-shaped circuit are controlled to be conducted, and the direct current power supply works in a current source mode to boost or keep a magnetic field for the superconducting coil; when the voltage of the capacitor is larger than the preset voltage of the direct current power supply, the power diode of the power supply branch is cut off, the current of the power supply branch is reduced to zero, the power supply works in a voltage source mode, and the capacitor is used for exciting the superconducting coil; in an initial state that the capacitor voltage is zero and the current of the superconducting coil is zero, controlling the two power switches of a bridge arm at the opposite side of the H-shaped circuit to be conducted, and loading current to the superconducting coil by a direct current power supply for excitation; the following three control logics are then sequentially executed in cycles:
When the specified magnetic field reaches the specified duration, the control logic I controls the two power switches of the opposite side bridge arm of the H-shaped circuit to be turned off, and the power diodes of the other two bridge arms are turned on because the current of the superconducting coil cannot be suddenly changed, the superconducting coil charges the capacitor, and most of magnetic energy in the superconducting coil is converted into electric field energy in the capacitor;
When the capacitor voltage reaches the vicinity of the maximum value or the current of the superconducting coil is reduced to be close to zero, the control logic II controls one power switch of the H-shaped circuit to be conducted, so that the current of the superconducting coil is reliably reduced to zero;
The control logic III controls the conduction of the two power switches of the opposite-side bridge arm of the H-shaped circuit when the zero magnetic field reaches the appointed duration, and discharges the capacitor to the superconducting coil when the voltage of the capacitor is higher than the voltage of the direct-current power supply; when the capacitor voltage is lower than the DC power supply voltage, the power diode in the power supply branch is conducted, and the DC power supply continues to supply current to the superconducting coil until a preset current value is reached, and meanwhile, a specified magnetic field is reached.
2. The method for controlling a periodic lifting magnetic circuit of a superconducting magnet according to claim 1, wherein in the second control logic, a power switch of a bridge arm connected with a negative electrode of a direct current power supply is controlled to be turned on.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4695932A (en) * | 1985-05-15 | 1987-09-22 | Mitsubishi Denki Kabushiki Kaisha | Superconductive energy storage circuit |
| CN201616765U (en) * | 2009-12-21 | 2010-10-27 | 中国电力科学研究院 | DSP-based power conversion device for high-temperature superconductive energy-storage system |
| CN103546057A (en) * | 2013-10-12 | 2014-01-29 | 华中科技大学 | High-voltage large-power repetition pulse power supply |
| CN109980743A (en) * | 2019-04-16 | 2019-07-05 | 中国人民解放军国防科技大学 | Pre-polarizing coil current control system and control method for low-field nuclear magnetic resonance |
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2021
- 2021-12-10 CN CN202111505811.3A patent/CN114070065B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4695932A (en) * | 1985-05-15 | 1987-09-22 | Mitsubishi Denki Kabushiki Kaisha | Superconductive energy storage circuit |
| CN201616765U (en) * | 2009-12-21 | 2010-10-27 | 中国电力科学研究院 | DSP-based power conversion device for high-temperature superconductive energy-storage system |
| CN103546057A (en) * | 2013-10-12 | 2014-01-29 | 华中科技大学 | High-voltage large-power repetition pulse power supply |
| CN109980743A (en) * | 2019-04-16 | 2019-07-05 | 中国人民解放军国防科技大学 | Pre-polarizing coil current control system and control method for low-field nuclear magnetic resonance |
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