Annular field coil power supply of nuclear fusion magnet power supply system based on super capacitor

Abstract

The invention discloses an annular field coil power supply of a nuclear fusion magnet power supply system based on a supercapacitor. The annular field coil power supply comprises a charger module, an MMC array module, an annular field coil, a first switch module and a second switch module, the MMC array module comprises a super capacitor; the charger module is used for charging the MMC array module; the MMC array module stores energy from the charger module based on a supercapacitor and is used for outputting a power pulse signal to the annular field coil based on the stored energy; the first switch module and the second switch module are used for controlling the circuit connection of the annular field coil power supply of the nuclear fusion magnet power supply system. According to the invention, based on the characteristic that the supercapacitor has high power density, the MMC array module has efficient electric energy conversion capability, so that the MMC array module can more effectively manage rapid flow of large-scale energy, and can more efficiently supply power to the annular field coil especially in a pulse operation mode of a nuclear fusion device.

Description

Technical Field

[0001] The invention relates to the field of electronic circuits, in particular to a toroidal field coil power supply of a nuclear fusion magnet power supply system based on a supercapacitor. Background Art

[0002] The large and medium-sized Tokamak devices that have been built or are under construction in the world mainly include: KSTAR, JET, EAST, JT-60SA and the ITER project jointly invested and built by multiple governments. Depending on the load operating capacity and power supply energy, different devices adopt different power supply methods and distribution schemes. The current mainstream method is direct power supply from the power grid, but there are large problems of large capacity and volatile impact power in the Tokamak device. In addition, the Tokamak reactor does not currently have steady-state operation conditions, and its power supply system must be designed to support pulse operation, which also exacerbates the fluctuations on the power supply side. Therefore, in the design and operation of the power supply system of the Tokamak device, its compatibility with the power grid is an important factor that cannot be ignored.

[0003] Existing nuclear fusion devices such as HL-2A and HL-2M adopt pulse power supply system for power supply. Through the switching circuit, the 300MV·A pulse generator set can supply power to the toroidal field (TF) coil power supply and the poloidal field (PF) coil power supply respectively. The schematic diagram is shown in Figure 1 The pulse generator set adopts a vertical structure flywheel generator (FG), which is composed of a 300MV·A synchronous generator and an 8500kW wound-rotor asynchronous motor coaxially.

[0004] Although FG provides important power support, it has limitations when a major failure occurs or a quick response is required. The mechanical structure and operating mechanism of FG limit its ability to respond quickly and dynamically, and there is a lack of similar equipment on the market that can be quickly replaced, which may cause instability in the power system in an emergency. In addition, FG has high maintenance costs and a relatively short lifespan, especially in a high-frequency start-stop operating environment. Summary of the invention

[0005] The present invention provides a supercapacitor-based toroidal field coil power supply for a nuclear fusion magnet power supply system to solve the above-mentioned technical problems and effectively improve the energy conversion efficiency.

[0006] In order to solve the above technical problems, the present invention provides a toroidal field coil power supply for a nuclear fusion magnet power supply system based on a supercapacitor, comprising: a charger module, an MMC array module, a toroidal field coil, a first switch module and a second switch module; the MMC array module comprises a supercapacitor;

[0007] The charger module is used to charge the MMC array module;

[0008] The MMC array module stores energy from the charger module based on supercapacitors and is used to output power pulse signals to the toroidal field coil based on the stored energy;

[0009] The first switch module is used to electrically connect the charger module and the MMC array module when the charger module charges the MMC array module; and disconnect the electrical connection between the charger module and the MMC array module when the MMC array module supplies power to the toroidal field coil;

[0010] The second switch module is used to disconnect the electrical connection between the MMC array module and the annular field coil when the charger module charges the MMC array module; and to electrically connect the MMC array module and the annular field coil when the MMC array module supplies power to the annular field coil.

[0011] The beneficial effects of the present invention are:

[0012] The present invention controls two switch modules and utilizes a charger module to charge an MMC array module, so that the MMC array module stores energy from the charger module based on a supercapacitor, and outputs a power pulse signal to the annular field coil based on the stored energy; thus, the present invention realizes high-power pulses through a switch module, a charger module and an MMC array module including a supercapacitor, wherein the supercapacitor has the characteristics of high power density, can release a large amount of energy in a short time, and provide instantaneous large current, which is suitable for application scenarios requiring rapid response, so that the MMC array module has efficient power conversion capabilities, so that the present invention can more effectively manage the rapid flow of large-scale energy, especially in the pulse operation mode of the nuclear fusion device, and can more efficiently power the annular field coil.

[0013] As a preferred solution, the MMC array module includes N×M SM units arranged in a matrix of N rows and M columns, where N and M are preset positive integers; wherein the SM units in the same column are connected in series, and the SM units in the same row are connected in parallel; and the SM units in the first row are electrically connected to the first switch module and the second switch module.

[0014] As a preferred solution, each SM unit includes a half-bridge subunit and a supercapacitor;

[0015] The first end of the half-bridge subunit serves as the first input end of the SM unit;

[0016] The second end of the half-bridge subunit serves as the second input end of the SM unit;

[0017] The third end of the half-bridge subunit is electrically connected to the first end of the supercapacitor;

[0018] The second end of the half-bridge subunit is electrically connected to the second end of the supercapacitor;

[0019] Each SM unit is connected in parallel or in series with other SM units or electrically connected to the first switch module and the second switch module through the first input end and the second input end.

[0020] As a preferred solution, the charger module includes a boost charger; the boost charger is used to charge the MMC array module in the boost charging stage.

[0021] As a preferred solution, the boost charger includes a three-phase rectifier and an inductor;

[0022] Wherein, the input end of the three-phase rectifier is set as a charging interface of the charger module;

[0023] The first output terminal of the three-phase rectifier is electrically connected to the first end of the inductor;

[0024] The second end of the inductor is electrically connected to the first switch module.

[0025] As a preferred solution, the charger module further includes a pre-charger; the pre-charger is used to charge the MMC array module in a pre-charging stage so that the voltage of the MMC array module reaches a preset voltage.

[0026] As a preferred solution, the first switch module includes a first switch and a second switch;

[0027] Wherein, the first switch is used to control the electrical connection between the boost charger and the MMC array module;

[0028] The second switch is used to control the electrical connection between the pre-charger and the MMC array module.

[0029] As a preferred solution, the pre-charger is a buck rectifier.

[0030] As a preferred solution, a corresponding unit controller is provided for each SM unit; the unit controller is used to isolate the corresponding SM unit when a fault occurs in the corresponding SM unit.

[0031] As a preferred solution, the supercapacitor-based nuclear fusion magnet power system toroidal field coil power supply also includes a distributed clock module; the distributed clock module is used to calculate and compensate for the jitter between unit controllers during network initialization to synchronize each SM unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 : A schematic diagram of the HL-2M provided in an embodiment of the present invention using a pulse power supply system to power the TF coil;

[0033] Figure 2: A waveform diagram of voltage and current of a Tokamak TF coil provided in an embodiment of the present invention;

[0034] Figure 3 : A circuit diagram of a conventional three-phase MMC converter topology structure provided by an embodiment of the present invention;

[0035] Figure 4 : A schematic diagram of a half-bridge switch state in a conventional three-phase MMC converter topology structure provided by an embodiment of the present invention;

[0036] Figure 5 : A schematic diagram of the structure of a toroidal field coil power supply for a nuclear fusion magnet power supply system based on a supercapacitor provided in an embodiment of the present invention;

[0037] Figure 6 : A circuit diagram of a toroidal field coil power supply for a nuclear fusion magnet power supply system based on a supercapacitor provided in an embodiment of the present invention;

[0038] Figure 7 : A schematic diagram of the signal flow of the MMC array module in the pre-charging stage and the boost charging stage respectively provided by an embodiment of the present invention;

[0039] Figure 8 : A current and voltage waveform diagram of the SM unit in the pre-charging stage provided by an embodiment of the present invention;

[0040] Fig. 9 : A current and voltage waveform diagram of the SM unit in the boost charging stage provided by an embodiment of the present invention;

[0041] Fig.10 : A waveform diagram of current and voltage of a toroidal field coil in a flat-top stage provided by an embodiment of the present invention;

[0042] Fig.11 : A voltage waveform diagram of a toroidal field coil provided by an embodiment of the present invention during a standard 30-second pulse;

[0043] Fig.12 : A current waveform diagram of a toroidal field coil provided by an embodiment of the present invention during a standard 30-second pulse;

[0044] Fig.13 : A voltage waveform diagram of the SM unit during a standard pulse period provided by an embodiment of the present invention;

[0045] Fig.14 : A current waveform diagram of the SM unit during a standard pulse provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Existing nuclear fusion devices such as HL-2A and HL-2M adopt pulse power supply system for power supply. Through the switching circuit, the 300MV·A pulse generator set can supply power to the toroidal field (TF) coil power supply and the poloidal field (PF) coil power supply respectively. The schematic diagram is shown in Figure 1 The pulse generator set adopts a vertical structure flywheel generator (FG), which is composed of a 300MV·A synchronous generator and an 8500kW wound asynchronous motor coaxially. For the reactor pulse load, because the PF coil needs to control and adjust the shape and position of the plasma, this requires the power supply system to have a high degree of dynamic response capability and adjustment flexibility. Therefore, the MMC power conversion topology design for the PF coil was carried out early, and there are relevant literatures.

[0048] Although FG provides important power support, it has limitations when a major failure occurs or a quick response is required. The mechanical structure and operating mechanism of FG limit its ability to respond quickly and dynamically, and there is a lack of similar equipment on the market that can be quickly replaced, which may cause instability in the power system in an emergency. In addition, FG has high maintenance costs and a relatively short lifespan, especially in a high-frequency start-stop operating environment.

[0049] Taking the HL-2M project as an example, the TF coil is powered by an FG combined diode inverter. Multiple non-superconducting TF coils connected in series can be equivalent to a load of an inductor and a resistor.

[0050] Figure 2 The waveform diagram of the voltage and current of the Tokamak TF coil provided in the embodiment of the present invention.

[0051] in, Figure 2 The main electrical requirements of the HL-2M project TF coil during a typical plasma pulse cycle are shown. Figure 2 The left side of the 0 value is the rising stage, and the right side of the 0 value is the flat top stage.

[0052] like Figure 2As shown, the current first increases, then remains smooth and constant during the flat-top phase, and finally decreases at the end of the pulse. The impedance of the TF coil is almost completely constant and decoupled from the other loads of the tokamak. The increase and decrease of the current are not ideal flat-top waves, because the current control is directly achieved by modifying the excitation voltage of the FG, which has a large time constant. In addition, it can be seen that the voltage of the TF current increase phase is higher than that of the flat-top phase, while the voltage of the flat-top phase is a constant value to cover the ohmic losses. A detailed description of the actual power supply of the tokamak can be found in the relevant literature.

[0053] Since the beginning of this century, modular multilevel converters (MMCs) have attracted widespread attention for their potential applications in high-power devices and high-voltage direct current (HVDC) transmission systems. MMC topologies are mainly used in high-voltage direct current transmission (HVDC), medium-voltage applications, and flexible AC transmission systems. Compared with traditional two-stage converters, MMCs show several advantages: it provides scalable output voltage, decentralized energy storage, and in the event of a fault, damaged submodules (SMs) can be replaced. These advantages are now increasingly valued in the field of nuclear fusion.

[0054] See below Figure 3 and Figure 4 . Figure 3 A circuit diagram of a conventional three-phase MMC converter topology structure provided by an embodiment of the present invention; Figure 4 A schematic diagram of the half-bridge switch state in a conventional three-phase MMC converter topology provided by an embodiment of the present invention.

[0055] like Figure 3 As shown, the conventional three-phase MMC converter topology consists of six arms, each of which includes a series connection of n units and an inductor L. Each SM unit (or switching module) includes a half-bridge consisting of two IGBTs and a capacitor.

[0056] like Figure 4 As shown, the capacitor charging voltage is v c , which is affected by the phase current flowing through the three-phase load. Each SM unit can switch between two different states, where ON-state: current flows through the upper switch (v sm =v c ); OFF-state: current flows through the lower switch (v sm =0).

[0057] If r of the n units are in the ON-state (where 0≤r≤n), the sum of the voltages of the r capacitors will be generated on the corresponding phase. The main advantages of the traditional three-phase MMC converter include: scalable voltage; faulty modules can be replaced; the stored energy is distributed in the SM unit, so it can be better handled in the event of a fault; simple structure, etc. The challenge of implementing this topology comes from the large number of semiconductors and gate control units, which makes the controller more complex.

[0058] Besides this, supercapacitors (SC) are known for their high power density and some applications with high power requirements of Tokamak coils based on supercapacitors are already under development. To increase the energy storage of SM units, an alternative worth exploring is based on supercapacitors. However, supercapacitors cannot be directly connected to the coils and they require a suitable conversion topology capable of driving its output current in a controlled manner. Indeed, during the pulse, in order to ensure proper plasma confinement, the toroidal magnetic field fluctuations must not exceed a fixed value. Since it strictly depends on the toroidal field coil current fluctuations, a suitable converter capable of controlling this current must be used.

[0059] Embodiment 1

[0060] In order to solve the technical problems existing in the prior art, the present invention provides a toroidal field coil power supply for a nuclear fusion magnet power supply system based on a supercapacitor, which effectively improves the energy conversion efficiency.

[0061] Please refer to Figure 5 , Figure 5 A schematic structural diagram of a toroidal field coil power supply for a nuclear fusion magnet power supply system based on a supercapacitor provided in an embodiment of the present invention.

[0062] like Figure 5 As shown, the toroidal field coil power supply of the nuclear fusion magnet power supply system based on supercapacitor includes: a charger module, an MMC array module, a toroidal field coil, a first switch module and a second switch module; the MMC array module includes a supercapacitor;

[0063] The charger module is used to charge the MMC array module;

[0064] The MMC array module stores energy from the charger module based on supercapacitors and is used to output power pulse signals to the toroidal field coil based on the stored energy;

[0065] The first switch module is used to electrically connect the charger module and the MMC array module when the charger module charges the MMC array module; and to disconnect the electrical connection between the charger module and the MMC array module when the MMC array module supplies power to the toroidal field coil;

[0066] The second switch module is used to disconnect the electrical connection between the MMC array module and the annular field coil when the charger module charges the MMC array module; and to electrically connect the MMC array module and the annular field coil when the MMC array module supplies power to the annular field coil.

[0067] The present invention controls two switch modules and uses a charger module to charge the MMC array module, so that the MMC array module stores energy from the charger module based on a supercapacitor, and outputs a power pulse signal to the annular field coil based on the stored energy; thus, the present invention realizes high-power pulses through the switch module, the charger module and the MMC array module including the supercapacitor, wherein the supercapacitor has the characteristics of high power density and fast charging and discharging, can release a large amount of energy in a short time, and provide instantaneous large current, which is suitable for application scenarios requiring fast response, and the MMC topology has efficient power conversion capability. The present invention combines the supercapacitor and the MMC topology, so that the present invention can more effectively manage the rapid flow of large-scale energy, especially in the pulse operation mode of the nuclear fusion device, and can more efficiently power the annular field coil.

[0068] See below Figure 6 , Figure 6 A circuit diagram of a toroidal field coil power supply for a nuclear fusion magnet power supply system based on a supercapacitor provided in an embodiment of the present invention.

[0069] The annular field coil can be equivalent to a resistor and an inductor connected in series; Figure 6 In the embodiment, the toroidal field coil is represented by a series RL circuit, which includes an equivalent resistance and an equivalent inductance, wherein V L Vcu represents the voltage across the equivalent inductance of the toroidal field coil, and Vcu represents the voltage drop across the equivalent resistance of the toroidal field coil.

[0070] Furthermore, if Figure 6 As shown, the MMC array module includes N×M SM units arranged in a matrix of N rows and M columns, where N and M are preset positive integers; wherein the SM units in the same column are connected in series, and the SM units in the same row are connected in parallel; and the SM units in the first row are electrically connected to the first switch module and the second switch module.

[0071] Furthermore, if Figure 6 As shown, each SM unit includes a half-bridge subunit and a supercapacitor;

[0072] The first end of the half-bridge subunit serves as the first input end of the SM unit;

[0073] The second end of the half-bridge subunit serves as the second input end of the SM unit;

[0074] The third end of the half-bridge subunit is electrically connected to the first end of the supercapacitor;

[0075] The second end of the half-bridge subunit is electrically connected to the second end of the supercapacitor;

[0076] Each SM unit is connected in parallel or in series with other SM units or electrically connected to the first switch module and the second switch module through the first input end and the second input end.

[0077] In this embodiment, the half-bridge sub-unit includes two IGBT devices.

[0078] In this embodiment, considering that the toroidal field coil (TF coil) is a single-phase load, the MMC array module is a single-arm.

[0079] Furthermore, if Figure 6 As shown, the charger module includes a boost charger; the boost charger is used to charge the MMC array module in the boost charging stage.

[0080] Furthermore, if Figure 6 As shown, the boost charger includes a three-phase rectifier and an inductor;

[0081] Wherein, the input end of the three-phase rectifier is set as a charging interface of the charger module;

[0082] The first output terminal of the three-phase rectifier is electrically connected to the first end of the inductor;

[0083] The second end of the inductor is electrically connected to the first switch module.

[0084] In this embodiment, the charging interface of the charger module is connected to the AC power grid so that the three-phase rectifier rectifies the voltage and current from the 50 Hz bus.

[0085] Furthermore, if Figure 6 As shown, the charger module also includes a pre-charger; the pre-charger is used to charge the MMC array module in the pre-charging stage so that the voltage of the MMC array module reaches a preset voltage.

[0086] Furthermore, if Figure 6 As shown, the first switch module includes a first switch and a second switch;

[0087] Wherein, the first switch is used to control the electrical connection between the boost charger and the MMC array module;

[0088] The second switch is used to control the electrical connection between the pre-charger and the MMC array module.

[0089] Furthermore, the pre-charger is a buck rectifier.

[0090] In this embodiment, the pre-charger is specifically a low-power buck rectifier.

[0091] Furthermore, a corresponding unit controller is provided for each SM unit; the unit controller is used to isolate the corresponding SM unit when a fault occurs in the corresponding SM unit.

[0092] Furthermore, the supercapacitor-based nuclear fusion magnet power system toroidal field coil power supply also includes a distributed clock module; the distributed clock module is used to calculate and compensate for jitter between unit controllers during network initialization to synchronize each SM unit.

[0093] In this embodiment, synchronization between SM units or row arrays is ensured based on the distributed clock module: each unit controller has its own clock, which is synchronized with the reference clock (usually the clock of the first SM unit in the row); during network initialization, the jitter between unit controllers is calculated and compensated. The first and last two communication paths of each row ensure redundancy when an SM unit fails. The distributed clock module is the basis for realizing array switch control. This embodiment can perform fault isolation of SM units based on the distributed clock module and has scalability.

[0094] Furthermore, the present invention sets a main controller for the MMC array module; sets a row controller for M SM units belonging to the same row; the main controller is used to communicate with the row controller to receive information of each row, and control the MMC array module based on the information of each row.

[0095] In this embodiment, each row (defined as M parallel and synchronous SM units) has a row controller and M unit controllers: the row controller only communicates with the first and last SM units in its row (ring topology), and gating signals, voltage, current, temperature and SM status information are exchanged between adjacent unit controllers.

[0096] In this embodiment, the failure of SM cells is managed locally by the cell controller (the row controller only receives information about their status): through an additional switch, its cell controller will isolate the faulty SM cell without affecting the operation of the row, and the current will flow through the other M-1 SM cells due to the inter-arm connection. The main controller communicates with the main communication bus of the N row controllers, receiving voltage, current and row status information from them, and finally implements the current control, selecting which rows to connect / disconnect according to their voltage levels.

[0097] Based on distributed clock modules, each SM unit and its unit controller, row controller and main controller, the present invention has the best scalability, when the required power electronic devices are developed, the total array can be expanded and replicated no matter how large the energy demand is.

[0098] Next, this embodiment describes a specific charging process based on the circuit of the toroidal field coil power supply of the nuclear fusion magnet power supply system based on supercapacitors as described above.

[0099] In this embodiment, it is assumed that each supercapacitor is composed of 48 2.7V capacitors connected in series, with a rated voltage of 130V, a capacitance of 71F, and a peak current of 2kA. According to the proposed topology of the toroidal field coil power supply of the nuclear fusion magnet power supply system based on supercapacitors, in order to supply all loads of the toroidal field coil, 23 rows of SM units in series (N) and 30 in parallel (M) will be required to achieve a voltage of 3kV (including a safety margin of 400V) and a current of 20kA required during the pulse, that is, a total of about 700 supercapacitors are required.

[0100] In this embodiment, the charging process of the charger module charging the MMC array module is divided into two sub-stages: a pre-charging stage and a boost charging stage; at this time, the MMC array module and the toroidal field coil are disconnected under the control of the second switch module.

[0101] See below Figure 7 , Figure 7 A schematic diagram of signal flow of an MMC array module in a pre-charging stage and a boost charging stage provided by an embodiment of the present invention.

[0102] The pre-charging stage is realized by a low-power buck rectifier: it charges each SC simultaneously so that each SC gradually reaches the voltage required in the boost charging stage.

[0103] In the boost charging phase, each SC is charged to its full voltage by a boost charger based on a boost rectifier (three-phase rectifier), which is implemented with power IGBTs for scalability. In this phase, the inductor first stores energy at the charging current change rate di / dt, and then uses this energy to charge each SC. In order to transfer the energy stored in the inductor to each SC, the current change rate di L / dt must be negative (the energy expression of the inductor is 0.5LI 2 , where L is the inductance value and I is the current through the inductor; any change in the current affects the energy stored in the inductor).

[0104] The voltage across the inductor is given by:

[0105] VL≈Vi-V0

[0106] Among them, Vo is the output voltage of the boost charger and Vi is the input voltage.

[0107] The value of the output voltage Vo must be higher than the input voltage Vi, so an additional pre-charger is required.

[0108] In order to better understand the charging process, this embodiment simulates the voltage and current waveforms of a single SM unit.

[0109] See below Figure 8 and Fig. 9 . Figure 8 The current and voltage waveforms of the SM unit in the pre-charging stage provided by the embodiment of the present invention; Fig. 9 The current and voltage waveforms of the SM unit provided in the embodiment of the present invention during the boost charging stage.

[0110] Taking into account the voltage and current limitations (in this embodiment, the single SM unit is set to be rated at 10A and the pre-charge upper limit is 70V during simulation) and the number of parallel modules in the toroidal field coil power topology of the supercapacitor-based nuclear fusion magnet power system, a 40kW pre-charger takes approximately 10 minutes to charge each group of supercapacitor modules to 70V with a total current of 300A (30 parallel modules).

[0111] The constraints of the boost charging stage are the available power and the charging time: the former is the maximum power available from the AC grid (assumed to be 5 MW in the simulation), and the latter should be minimized; with a total charging current of 2.1 kA (70 A per arm) and an input voltage of 1.5 kV, the boost charger takes about 120 seconds to charge the supercapacitor to full voltage.

[0112] When the supercapacitors in each SM unit are fully charged, they are ready to power the toroidal field coils with the stored energy. At this time, the charger module and the MMC array module are disconnected by the first switch module, and the MMC array module and the toroidal field coils are connected by the second switch module. When the MMC array module powers the toroidal field coils, the MMC array module can be regarded as a variable voltage source.

[0113] During the current rise phase, the current flowing through the TF coil (toroidal field coil) should be increased to 20kA or higher as quickly as possible (a faster rise phase means less energy loss in this time frame). To this end, the power supply output voltage needs to be maximized. All available matrix rows in the MMC array module need to be utilized to keep the output voltage as high as possible.

[0114] During the plateau phase, the current should remain at a high level for a period of time (depending on the requirements of the plasma pulse), but in practice, the coil current of the toroidal field coil will fluctuate (Δi), which must be maintained at i at the equivalent inductor current i Coils Less than 0.1% of the current value. Δi is defined as:

[0115]

[0116] Wherein, Vs is the power supply voltage. In this embodiment, the power supply voltage is the output voltage of the MMC array module when the MMC array module supplies power to the toroidal field coil; Vcu is the voltage drop of the equivalent resistor; t on is the time when Vs-Vcu is positive (Δi is positive), t off is the time when Vs-Vcu is negative (Δi is negative); L Coils is the inductance value of the equivalent inductance of the toroidal field coil.

[0117] See below Fig.10 , Fig.10 A waveform diagram of current and voltage of a toroidal field coil in a flat-top stage provided by an embodiment of the present invention.

[0118] Fig.10 The ideal state of the current and voltage waveforms in the flat-top stage after amplification under high-frequency switching state is shown (ignoring the change of Vcu caused by Δi and supercapacitor voltage loss), and the dotted line is used to emphasize the on and t off Assumed value of period Vs.

[0119] from Fig.10 It can be seen that when Vs>Vcu, i Coils When Vs is less than Vcu, it decreases at the slope of |Vs-Vcu|, and then this difference is minimized. Minimizing |Vs-Vcu| means that Vs takes the closest available value to Vcu (Δv depends on the smallest unit that the MMC topology can operate). Increasing the switching frequency of the IGBTs in the SM unit can also limit Δi (t on / t off will decrease), but this will increase the switching losses of the power electronic switches and reduce the life of the supercapacitor. Therefore, efforts will be made to keep the switching frequency as low as possible, and the preferred method to reduce current fluctuations is to adjust the voltage.

[0120] During the current drop phase, the SM unit is short-circuited and the energy of the toroidal field coil is dissipated in its internal resistance. Coils The change in is negative and becomes zero once all the energy stored in the toroidal field coils has been exhausted. In principle, this energy can be recovered and used to charge the supercapacitor. But in this case, the SM unit will have to be an IGBT full bridge instead of a half bridge, which will double the conduction losses of the power electronics, because in a full bridge configuration, two IGBTs will be conducting continuously, while in a half bridge configuration only one will be conducting.

[0121] See below Fig.11 and Fig.12 . Fig.11A voltage waveform diagram of a toroidal field coil during a standard 30-second pulse provided by an embodiment of the present invention; Fig.12 A current waveform diagram of the toroidal field coil provided in an embodiment of the present invention during a standard 30-second pulse.

[0122] Fig.11 and Fig.12 The waveform simulation of the toroidal field coil during the complete pulse stage shows the i during a standard 30-second pulse. Coils , ν s and the required power, it can be seen that Figure 2 Compared with the FG pulse power supply of the present invention, the simulation curve obtained by the toroidal field coil power supply of the nuclear fusion magnet power supply system based on the supercapacitor is basically consistent with it, and the response speed is faster. Therefore, the MMC array module of the present invention can realize high-power intermittent pulse as a short-term energy storage device.

[0123] See below Fig.13 and Fig.14 . Fig.13 A voltage waveform diagram of the SM unit during a standard pulse provided by an embodiment of the present invention; Fig.14 A current waveform diagram of the SM unit during a standard pulse period provided by an embodiment of the present invention.

[0124] Fig.13 and Fig.14 The voltage and current curves of a single SM unit during a plasma pulse are shown. During the flat-top phase, the SM units are mainly used to compensate for copper losses, and they are in a high-frequency switching operation mode. From the perspective of the toroidal field coil, a switching frequency of 4 Hz is sufficient to keep the current fluctuations below 0.1%, but in order to keep the SM unit voltage balanced, it will be operated at a higher frequency.

[0125] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0126] 1. In order to meet the need of replacing FG, the present invention focuses on the design of a power supply based on supercapacitors for the TF coil power supply in the reactor pulse load, and proposes a toroidal field coil power supply for a nuclear fusion magnet power supply system based on supercapacitors. In the present invention, supercapacitors are used as energy storage devices in SM units, and the total output current can be selectively increased through the parallel operation of multiple SMs. Among them, the present invention uses supercapacitors as energy storage devices in SM units, which enhances the energy storage capacity and rapid response characteristics of the toroidal field coil power supply of the nuclear fusion magnet power supply system. By precisely controlling the switching state of each SM unit, the present invention can switch from the storage state to the energy release state in a very short time, meeting the demand for rapid dynamic response of the nuclear fusion device. Therefore, the present invention achieves higher energy density and power density by combining the use of supercapacitors and MMC topology structures, while improving the efficiency, stability and reliability of overall energy storage.

[0127] 2. The high number of units in the MMC array module of the present invention provides higher flexibility than that of FG. When some SM units fail, the MMC array module can still continue to operate, while FG cannot do this.

[0128] 3. The present invention proposes a communication architecture of a main controller, a row controller and a unit controller of an SM unit, which can meet the demand for unlimited scalability of ultra-high power coil power supply through an expandable power module and a centralized-distributed control method.

[0129] 4. The present invention has lower energy consumption (the average efficiency of the present invention is 90% to 95%, while the efficiency of the traditional flywheel system is about 85% to 90%) and maintenance cost (the maintenance cost of the present invention is about 1% of the total system cost per year, mainly for checking and replacing monitoring system components; in contrast, the flywheel system involves mechanical moving parts, and the maintenance cost is as high as 3% to 5% of the total cost) and longer service life (the service life of the present invention can reach 10 to 15 years, while the average service life of the flywheel system is about 8 to 10 years).

[0130] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A toroidal field coil power supply for a nuclear fusion magnet power supply system based on a supercapacitor, characterized in that: include: A charger module, an MMC array module, a toroidal field coil, a first switch module and a second switch module; The MMC array module includes a supercapacitor; The charger module is used to charge the MMC array module; The MMC array module stores energy from the charger module based on supercapacitors and is used to output power pulse signals to the toroidal field coil based on the stored energy; The first switch module is used to electrically connect the charger module and the MMC array module when the charger module charges the MMC array module; and disconnect the electrical connection between the charger module and the MMC array module when the MMC array module supplies power to the toroidal field coil; The second switch module is used to disconnect the electrical connection between the MMC array module and the annular field coil when the charger module charges the MMC array module; and to electrically connect the MMC array module and the annular field coil when the MMC array module supplies power to the annular field coil.

2. The supercapacitor-based toroidal field coil power supply for a nuclear fusion magnet power supply system according to claim 1, characterized in that: The MMC array module includes N×M SM units arranged in a matrix of N rows and M columns, where N and M are preset positive integers; wherein the SM units in the same column are connected in series, and the SM units in the same row are connected in parallel; and the SM units in the first row are electrically connected to the first switch module and the second switch module.

3. The supercapacitor-based toroidal field coil power supply for a nuclear fusion magnet power supply system according to claim 2, characterized in that: Each SM unit includes a half-bridge subunit and a supercapacitor; The first end of the half-bridge subunit serves as the first input end of the SM unit; The second end of the half-bridge subunit serves as the second input end of the SM unit; The third end of the half-bridge subunit is electrically connected to the first end of the supercapacitor; The second end of the half-bridge subunit is electrically connected to the second end of the supercapacitor; Each SM unit is connected in parallel or in series with other SM units or electrically connected to the first switch module and the second switch module through the first input end and the second input end.

4. The toroidal field coil power supply for a nuclear fusion magnet power supply system based on a supercapacitor as claimed in claim 1, characterized in that: The charger module comprises a boost charger; the boost charger is used to charge the MMC array module in the boost charging stage.

5. The supercapacitor-based toroidal field coil power supply for a nuclear fusion magnet power supply system according to claim 4, characterized in that: The boost charger includes a three-phase rectifier and an inductor; Wherein, the input end of the three-phase rectifier is set as a charging interface of the charger module; The first output terminal of the three-phase rectifier is electrically connected to the first end of the inductor; The second end of the inductor is electrically connected to the first switch module.

6. The supercapacitor-based toroidal field coil power supply for a nuclear fusion magnet power supply system according to claim 4, characterized in that: The charger module also includes a pre-charger; the pre-charger is used to charge the MMC array module in the pre-charging stage so that the voltage of the MMC array module reaches a preset voltage.

7. The supercapacitor-based toroidal field coil power supply for a nuclear fusion magnet power supply system according to claim 6, characterized in that: The first switch module includes a first switch and a second switch; Wherein, the first switch is used to control the electrical connection between the boost charger and the MMC array module; The second switch is used to control the electrical connection between the pre-charger and the MMC array module.

8. The supercapacitor-based toroidal field coil power supply for a nuclear fusion magnet power supply system according to claim 6, characterized in that: The pre-charger is a buck rectifier.

9. The supercapacitor-based toroidal field coil power supply for a nuclear fusion magnet power supply system according to claim 2, characterized in that: A corresponding unit controller is provided for each SM unit; the unit controller is used to isolate the corresponding SM unit when a fault occurs in the corresponding SM unit.

10. The supercapacitor-based toroidal field coil power supply for a nuclear fusion magnet power supply system according to claim 9, characterized in that: The system also includes a distributed clock module, which is used to calculate and compensate for jitters between unit controllers during network initialization to synchronize the SM units.

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