Energy-recyclable pulsed high magnetic field generating device and method

Abstract

The present invention discloses an energy-recyclable pulsed high magnetic field generating device and method, belonging to the technical field of high magnetic fields. The device includes a main discharge circuit, a transformer discharge circuit, a freewheeling circuit, and a charging circuit; the main discharge circuit includes a first energy storage element, a first switch, a first unidirectional conduction element, and a magnet coil connected in series; the charging circuit includes a second energy storage element, a primary coil of a transducer transformer, a second switch, and a second unidirectional conduction element connected in series; the transformer discharge circuit and the freewheeling circuit are connected in parallel across the two ends of the first energy storage element; the transformer discharge circuit includes a secondary coil of the transducer transformer and a third unidirectional conduction element connected in series, and the freewheeling circuit includes a third switch and a fourth unidirectional conduction element connected in series. Through the coupling action of the transducer transformer, the present invention realizes energy recycling during the generation of pulsed high magnetic fields, and has the characteristics of reducing magnet heating and reusing energy.

Description

Technical Field

[0001] The present invention belongs to the technical field of high magnetic fields, and more specifically, relates to a pulsed high magnetic field generating device and method with recoverable energy. Background Art

[0002] Pulsed high magnetic field, as one of the most effective tools for modern scientific experiments, provides many scientific opportunities for generating new technologies and proposing new concepts. Pulsed high magnetic field refers to the magnetic field formed in space by instantaneously releasing a large amount of energy into a magnet coil to generate a pulsed current. Therefore, different magnetic field waveforms will be obtained by adopting different energy processing methods during the generation of pulsed high magnetic field, and thus different influences will be produced on the test results.

[0003] In electromagnetic forming applications, the magnetic field waveform will directly affect the induced eddy current in the formed specimen, and has a direct impact on the forming effect of this forming method driven by the electromagnetic force formed by the interaction between the induced eddy current in the specimen and the pulsed high magnetic field in space. Currently, at home and abroad, capacitors are used as power sources to discharge the coil to obtain a pulsed current waveform with a large rate of change, and this current waveform is a decaying oscillation waveform, as shown by Figure 1 the dotted line. However, the magnitude of the induced eddy current mainly depends on the rising stage of the pulsed current, and the decaying oscillation stage of the current instead enhances the springback and wrinkling degree of the specimen. The Wuhan National High Magnetic Field Laboratory took the lead in adding a freewheeling circuit to the circuit to solve the above problems. However, at the same time, it will increase the pulse width of the current waveform, as shown by Figure 1 the dot-dash line, resulting in an increase in the heating of the magnet coil during the first oscillation cycle of the current, and reducing the magnet performance.

[0004] Without changing the pulsed magnetic field waveform, the recovery and reuse of electromagnetic energy are the key technologies for realizing repetitive pulsed high magnetic field. Repetitive pulsed high magnetic field, as an extremely important experimental condition in modern scientific research, is widely used in basic scientific research such as neutron diffraction and magnetization. The National High Magnetic Field Laboratory of the United States introduced a feeding inductor in the design of the power supply topology. Although the reuse of energy was achieved and a repetitive pulsed high magnetic field of 2 Hz was generated, there are still problems that the inductance of the magnet load is limited by the feeding inductor and the magnetic field repetition frequency is limited by the charging power. For this reason, the Wuhan National High Magnetic Field Laboratory realized a high-frequency repetitive pulsed high magnetic field of 50 Hz by parallel use of multiple sets of power supply devices and controlling the discharge timing, but the number of repetitive pulses is limited by the configuration number of the power supply devices, and the relative cost is relatively high.

[0005] Generally speaking, the existing pulsed high magnetic field generation devices have the disadvantages of single energy processing method, large energy loss, low utilization efficiency and poor economy. In different application scenarios, there are also different disadvantages: in electromagnetic forming technology, the current waveform generated by the existing devices exacerbates the springback and wrinkling phenomena of the specimen during the forming process; in repetitive pulsed high magnetic field technology, there are disadvantages that the number of repetitive pulses is limited by the number of power supply configurations and the construction cost is high.

[0006] The present invention proposes an energy-recyclable pulsed high magnetic field generation device and method, which can eliminate the oscillation stage of the current waveform without changing the rising stage and pulse width of the current waveform. When applied to electromagnetic forming technology, it can improve the springback and wrinkling phenomena of the specimen. At the same time, since the device realizes energy recycling during the process of forming the pulsed magnetic field waveform, it is expected to solve the technical problem that the number of repetitive pulses is limited by the number of power supply devices. Summary of the Invention

[0007] In view of the above defects or improvement requirements of the existing technology, the present invention provides an energy-recyclable pulsed high magnetic field generation device and method, aiming to solve the problem of energy recycling and utilization in the existing pulsed high magnetic field, reduce energy loss, and improve the pulsed magnetic field waveform.

[0008] To achieve the above object, the present invention provides an energy-recyclable pulsed high magnetic field generation device, which includes a main discharge circuit, a transformer discharge circuit, a freewheeling circuit and a charging circuit;

[0009] The main discharge circuit includes a first energy storage element, a first switch, a first unidirectional conduction element and a magnet coil connected in series;

[0010] The charging circuit includes a second energy storage element, a primary coil of a transducer transformer, a second switch and a second unidirectional conduction element connected in series;

[0011] The transformer discharge circuit and the freewheeling circuit are connected in parallel across the first energy storage element; wherein, the transformer discharge circuit includes a secondary coil of a transducer transformer and a third unidirectional conduction element connected in series, and the freewheeling circuit includes a third switch and a fourth unidirectional conduction element connected in series.

[0012] Further, the energy storage element is a capacitor, and the unidirectional conduction element is a diode.

[0013] The present invention also provides a magnetic field generation method based on the above pulsed high magnetic field generation device, including the following steps:

[0014] Charge the first energy storage element to a preset voltage value;

[0015] Close the first switch and the second switch. The first energy storage element starts to discharge, and the discharge current flows through the magnet coil and then back to the first energy storage element to charge it reversely. After the first discharge is completed, the reverse discharge current of the first energy storage element passes through the transformer discharge circuit to discharge reversely the secondary coil of the transformer. At this time, the third switch in the freewheeling circuit is turned on.

[0016] When discharging reversely the secondary coil of the transformer, an induced current is generated in the charging circuit through the coupling action of the transducer transformer to charge the second energy storage element until the charging process ends.

[0017] Further, the preset voltage value is determined according to the required pulsed magnetic field intensity.

[0018] Further, the magnetic field generation method is applied to electromagnetic forming.

[0019] Further, the magnetic field generation method is applied to the generation of repetitive pulsed strong magnetic fields.

[0020] The present invention realizes energy recovery under pulsed strong magnetic fields by using a transducer transformer, and has the advantages of reducing losses, improving energy utilization rate, and reducing the heating of the magnet coil. At the same time, it has unique advantages in many application scenarios:

[0021] In the field of electromagnetic forming technology, compared with other circuit structures, the present invention keeps the waveform unchanged during the current rising stage of the magnet coil, does not affect the size of the induced eddy current, and at the same time, since there is no current oscillation decay stage, the springback and wrinkling of the specimen are improved, the heat generation of the magnet coil is reduced, and the performance of the magnet coil is guaranteed;

[0022] In the field of repetitive pulsed strong magnetic fields, since the present invention discharges a single magnet with a dual power supply, the problem that the magnetic field repetition frequency is limited by the charging time is improved, and at the same time, energy recovery is carried out, and the number of repetitive pulses will no longer be limited by the number of power supply devices configured. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of waveform comparison of different magnetic field devices in electromagnetic forming.

[0024] Figure 2 It is a schematic structural diagram of an energy recoverable pulsed strong magnetic field generating device provided by an embodiment of the present invention. Detailed Embodiments

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] Figure 2 Shown is a pulsed high magnetic field generating device with energy recovery provided by an embodiment of the present invention. For ease of illustration, only the circuit part related to the present invention is shown.

[0027] The device includes a main discharge circuit, a transformer discharge circuit, a freewheeling circuit, and a charging circuit;

[0028] The main discharge circuit includes a first capacitor C1, a first switch S1, a first diode D1, and a magnet coil connected in series in sequence. The inductance and internal resistance of the magnet coil are denoted as L and R1 respectively;

[0029] The charging circuit includes a second capacitor C2, a primary coil of a transducer transformer, a second switch S2, and a second diode D2 connected in series in sequence. The charging circuit is coupled to the main discharge circuit through the transducer transformer;

[0030] The transformer discharge circuit and the freewheeling circuit are connected in parallel across the first capacitor C1; wherein, the transformer discharge circuit includes a secondary coil of the transducer transformer and a third diode D3 connected in series in sequence, and the freewheeling circuit includes a third switch S3 and a fourth diode D4 connected in series in sequence.

[0031] Among them, the capacitor can be replaced by other energy storage elements with the same function as a power source, and the diode can be replaced by other unidirectional conduction elements with the same function.

[0032] In an embodiment of the present invention, when the freewheeling circuit is disconnected, the first capacitor discharges the magnet coil through the main discharge circuit to generate a pulsed magnetic field waveform. Subsequently, after the first capacitor is reversely charged, it discharges the transducer transformer. At this time, the freewheeling circuit is turned on, and the transformer discharge circuit will charge the second capacitor through the transducer transformer to complete the energy recovery process. The present invention realizes energy recovery under pulsed high magnetic fields through the coupling effect of the transducer transformer, providing a new idea for electromagnetic forming and the design of repetitive pulsed electromagnetic systems.

[0033] In an embodiment of the present invention, a magnetic field generation method based on the above-mentioned pulsed high magnetic field generating device with energy recovery includes the following steps:

[0034] Preparation stage: Charge the first capacitor C1 to a preset voltage value, which is determined according to the required magnetic field strength.

[0035] Discharging stage: Close the first switch S1 and the second switch S2. The first capacitor C1 starts to discharge, and the current passes through the first switch S1, the first diode D1, and the magnet coil in sequence, generating a pulsed magnetic field. After the discharge current flows through the magnet coil, it returns to the first capacitor C1 to charge the first capacitor C1 reversely. After the first discharge is completed, the reverse discharge current of the first capacitor C1 passes through the transformer discharge circuit to discharge reversely the secondary coil of the transformer. Due to the function of the first diode D1, it no longer flows through the magnet coil. At this time, the third switch S3 in the freewheeling circuit is turned on.

[0036] Charging stage: When discharging reversely the secondary coil of the transformer, through the coupling effect of the transducer transformer, the induced current passes through the primary coil of the transducer transformer, the second diode D2, and the second switch S2 to charge the second capacitor C2 until the charging process ends, generating a solid line waveform as shown in Figure 1 the figure.

[0037] Figure 1 The figure shows the current waveform of the magnet coil in the existing electromagnetic system, the current waveform of the magnet coil in the embodiment of the present invention, and the charging voltage waveform diagram after the energy is recovered to the second capacitor C2. It can be seen from the figure that compared with the existing electromagnetic system, the current flowing through the magnet coil does not have a decaying oscillation part, and the pulse width of the current waveform does not increase significantly. Therefore, it can be applied to the electromagnetic forming technology to change the current waveform in the magnet coil, thereby improving the phenomena of specimen springback and wrinkling during the electromagnetic forming process in the existing device, and at the same time reducing the heat generation of the magnet coil and extending its service life.

[0038] The present invention realizes the recovery and reuse of energy and can be applied to optimize the repetitive pulse generating device. In the repetitive pulse high magnetic field implementation method proposed by the Wuhan National High Magnetic Field Laboratory, the frequency of the generated repetitive pulses is high, but the number of repetitive pulses depends on the number of power supply devices. One power supply device can only generate a single pulse waveform in one experiment. Therefore, there is a problem that the continuity of the high-frequency repetitive pulses is limited. The energy recoverable pulsed high magnetic field device provided by the present invention can realize the recovery and utilization of energy between different power supplies, and use the mutual coordination between different capacitors to recover energy, which is expected to solve the waveform continuity problem in the above device, thereby increasing the repetitive pulse frequency and breaking through the problem that the number of repetitive pulses is limited by the number of power supply device configurations.

[0039] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An energy-recyclable pulsed high magnetic field generating device, characterized in that, the device includes a main discharge circuit, a transformer discharge circuit, a freewheeling circuit and a charging circuit; the main discharge circuit includes a first energy storage element (C1), a first switch (S1), a first unidirectional conduction element (D1) and a magnet coil connected in series; the charging circuit includes a second energy storage element (C2), a primary coil of a transducer transformer, a second switch (S2) and a second unidirectional conduction element (D2) connected in series; the transformer discharge circuit and the freewheeling circuit are connected in parallel across the two ends of the first energy storage element (C1); wherein, the transformer discharge circuit includes a secondary coil of a transducer transformer and a third unidirectional conduction element (D3) connected in series, and the freewheeling circuit includes a third switch (S3) and a fourth unidirectional conduction element (D4) connected in series; wherein, in the main discharge circuit, when the first energy storage element (C1) discharges, the discharge current sequentially passes through the first switch (S1), the first unidirectional conduction element (D1) and the magnet coil to generate a pulsed magnetic field, and after the discharge current flows through the magnet coil, it returns to the first energy storage element (C1) to charge the first energy storage element (C1) reversely; in the transformer discharge circuit, the secondary coil of the transducer transformer discharges reversely through the third unidirectional conduction element (D3), and an induced current is generated in the primary coil of the transducer transformer through the coupling action of the transducer transformer; in the charging circuit, the induced current in the primary coil of the transducer transformer charges the second energy storage element (C2) through the second unidirectional conduction element (D2) and the second switch (S2).

2. The pulsed high magnetic field generating device according to claim 1, characterized in that, the energy storage element is a capacitor.

3. The pulsed high magnetic field generating device according to claim 1, characterized in that, the unidirectional conduction element is a diode.

4. A magnetic field generating method based on the pulsed high magnetic field generating device according to any one of claims 1-3, comprising the following steps: charging the first energy storage element (C1) to a preset voltage value; closing the first switch (S1) and the second switch (S2), the first energy storage element (C1) starts to discharge, and the discharge current flows through the magnet coil and then returns to the first energy storage element (C1) to charge it reversely; after the first discharge is completed, the reverse discharge current of the first energy storage element (C1) passes through the transformer discharge circuit to discharge the secondary coil of the transformer reversely, and at this time, the third switch (S3) of the freewheeling circuit is turned on; when discharging the secondary coil of the transformer reversely, an induced current is generated in the charging circuit through the coupling of the transducer transformer to charge the second energy storage element (C2) until the charging process ends.

5. The magnetic field generating method according to claim 4, characterized in that, the preset voltage value is determined according to the required pulsed magnetic field intensity.

6. The magnetic field generating method according to claim 4 is applied to electromagnetic forming.

7. The magnetic field generating method according to claim 4 is applied to the generation of repetitive pulsed high magnetic fields.

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