Coupling control method and system of multi-coil transcranial magnetic stimulation system

Abstract

The invention belongs to the technical field of transcranial magnetic stimulation, and particularly provides a coupling control method and system of a multi-coil transcranial magnetic stimulation system.The method comprises the steps that a transient change formula of capacitor voltage and coil current in a coupling state is deduced based on the Kirchhoff's law, a circuit-electromagnetic field coupling model is established, and a current waveform accurate expression is given; capacitance values and accurate voltages in different modes are determined through the expression, and high synchronism of current waveforms is realized by combining capacitor switching and voltage regulation. According to the invention, the multi-coil current synchronism in a coupling state is improved, and effective stimulation and target switching of deep and shallow double targets are realized.

Description

Technical Field

[0001] This disclosure relates to the field of transcranial magnetic stimulation technology, and in particular to a coupling control method and system for a multi-coil transcranial magnetic stimulation system. Background Technology

[0002] Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique widely used in brain science research and the treatment of mental illnesses. Its principle is to induce neuronal activity in specific brain regions by delivering strong, short-lived electrical pulses to a stimulation coil placed above the scalp using a specific power system. Traditional TMS coils can only stimulate a localized area below the coil's center; to stimulate target areas at different locations or with different patterns (such as dual-target or deep targets), it is usually necessary to physically move or even replace the coil, which is cumbersome and inflexible. Using a pair of independent coils, given their relatively large size and fixed stimulation depth, it is also difficult to stimulate different targets. Integrated systems with multiple fixed coils are an effective way to overcome these limitations and achieve diverse stimulation modes. These systems spatially arrange multiple coils and coordinate their currents, using the principle of magnetic field superposition to synthesize complex and flexible electric field distributions. They can switch stimulation modes for different needs (such as simultaneously stimulating multiple superficial targets or focusing on a single deep target) without physical movement.

[0003] The effects of transcranial magnetic stimulation (TMS) are target-dependent; different brain regions often correspond to different diseases and different treatment effects. Herbsman et al. found that more anterolateral DLPFC targets are more effective for depression. Albino et al. pointed out that high-frequency stimulation of the M1 region promotes the reconstruction of motor function after stroke. Therefore, the development of a multi-coil, multi-target TMS system is of great significance for the treatment of mental illnesses.

[0004] However, electromagnetic coupling inevitably exists between closely adjacent coils. This coupling effect fundamentally alters the dynamic characteristics of the discharge circuits of each coil, making current control of the multiple coils difficult. Han et al. analyzed the mutual coupling effect between adjacent coils in a 4-channel magnetic stimulator and found that the coupling between coils generates induced currents in adjacent coils. When the coil array has a high magnetic coupling configuration, this may affect the spatial localization of the stimulus. They pointed out that the coupling effect can be compensated by appropriately controlling the charging voltage, but did not specify a method for adjusting the voltage to a certain level. Navarro et al. used a geometric decoupling method to design a 3-axis coil with orthogonal x / y / z axes in space, achieving automatic decoupling. Experiments verified that the mutual inductance was less than 0.1 μH, but the fixed design structure could not meet diverse stimulation needs.

[0005] In summary, multi-target transcranial magnetic stimulation (TMS) has overcome the limitations of single-coil physical movement through multi-coil synergistic stimulation, becoming an important development trend in the field of neuromodulation. However, the complexity of current modulation and synchronization issues caused by its multi-coil coupling effect urgently need to be addressed.

[0006] Furthermore, a search revealed that patent CN115498984A, "A Modular Multi-Level Transcranial Magnetic Stimulation Generator Topology and Control Method," achieves various stimulation current waveforms through the cascading of multiple modules. It focuses on waveform synthesis and circuit structure, without involving multiple coils or coupling between coils. Patent CN118593904A, "A Waveform-Controllable Dual-Channel Transcranial Magnetic Stimulation Experimental System," is a dual-channel stimulation system including host computer control and capacitor voltage conversion, thus containing two coils. It primarily emphasizes system composition and function. Its so-called mode switching refers to adjusting the capacitor voltage to change the stimulation current waveform in the two coils, without addressing waveform synchronization, stimulation effects, or methods for handling coupling between coils. Summary of the Invention

[0007] This disclosure aims to at least solve one of the technical problems existing in the prior art, and proposes a coupling control method and system for a multi-coil transcranial magnetic stimulation system.

[0008] In a first aspect, this disclosure provides a coupling control method for a multi-coil transcranial magnetic stimulation system, comprising: S1. Establish a coupled circuit model of the n-coil system. Each coil loop consists of a resistor, an inductor, a discharge capacitor, a diode, and a thyristor, where n is an integer greater than 2. S2, determine the expected current relationship of each coil circuit according to the target stimulus pattern, and calculate the equivalent inductance of each coil circuit; S3; Dynamically adjust the discharge capacitor value of each coil circuit to make the damping angular frequency of each coil circuit consistent; S4. Calculate the capacitor charging voltage based on the relationship between the equivalent inductance, the expected current, and the loop damping angular frequency. S5 controls all coil circuits to discharge synchronously, ensuring that the synchronization error of the current change rate is less than the preset value.

[0009] Preferably, in step S2, after the n coil loops are coupled, the formula for calculating the equivalent inductance of the nth coil loop is as follows: ; Among them, L n I n I represents the self-inductance and expected current of the Nth coil loop, respectively. m M is the expected current flowing through the m-th coil loop. nm Let be the mutual inductance between the nth coil loop and the mth coil loop.

[0010] Preferably, the damping angular frequency of each coil circuit in S3 The calculation formula is as follows: ; Among them, C n r n These are the discharge capacitance and resistance values ​​for the nth coil circuit, respectively.

[0011] Preferably, S4 specifically includes: The capacitor charging voltage U n The common terminal of the discharge capacitor and inductor applied to the nth coil circuit is given by the following formula: ; Preferably, in step S3, the discharge capacitance value of each coil circuit is dynamically adjusted to ensure that the damping angular frequency of each coil circuit is consistent, and finally the equivalent capacitance C of the nth coil circuit is obtained. n The following conditions must be met: ; Where k1 and k2 are both preset error coefficients.

[0012] Preferably, the formula for calculating the synchronization error ε of the current change rate in S5 is as follows: ; in, .

[0013] Preferably, S2 specifically includes: When n=4, the target stimulation pattern is three shallow and one deep stimulation. At this time, the expected currents of the first coil circuit, the second coil circuit, and the third coil circuit are the same and less than the expected current of the fourth coil circuit.

[0014] Preferably, S3 specifically includes: In the fourth coil circuit, a parallel capacitor is added to increase the discharge capacitance value.

[0015] The present invention also provides a coupling control system for a multi-coil transcranial magnetic stimulation system, the system being used to implement the coupling control method for the multi-coil transcranial magnetic stimulation system, the system comprising: The coil coupling module is configured to establish a coupling circuit model of an n-coil system. Each coil loop consists of a resistor, an inductor, a discharge capacitor, a diode, and a thyristor, where n is an integer greater than 2. The stimulation module is configured to determine the expected current of each coil circuit based on the target stimulation pattern and calculate the equivalent inductance of each coil circuit. The capacitance determination module is configured to dynamically adjust the discharge capacitance value of each coil circuit to ensure that the damping angular frequency of each coil circuit is consistent. The voltage compensation module is configured to calculate the capacitor charging voltage based on the relationship between the equivalent inductance, the expected current, and the loop damping angular frequency. The error adjustment module is configured to control the synchronous discharge of all coil circuits so that the synchronous error of the current change rate is less than a preset value.

[0016] Beneficial Effects: The method proposed in this invention is a coupled multi-coil TMS mode switching mechanism based on thyristor topology switching and capacitor voltage regulation. For the first time, it achieves flexible switching between "shallow dual-target" (Mode1) and "deep single-target" (Mode2) stimulation modes through hardware reconfiguration. By activating specific thyristor combinations (e.g., adding a capacitor in parallel to Mode1 in Mode2 to reduce the resonant frequency and ensure current synchronization), this method avoids the limitations of traditional methods that rely on physically moving coils to change the stimulation target. This design approach complements multi-focus TMS coil optimization (e.g., E-field control under current density constraints), providing a new path for switching in multi-mode, multi-coil coupled TMS systems. Attached Figure Description

[0017] Figure 1 A schematic diagram of coil circuit coupling for a coupling control method of a multi-coil transcranial magnetic stimulation system provided in this embodiment of the present disclosure; Figure 2 A circuit diagram of the coil circuit of a coupling control method for a multi-coil transcranial magnetic stimulation system provided in this embodiment of the present disclosure; Figure 3 Simulation waveforms of different modes of current for a coupling control method of a multi-coil transcranial magnetic stimulation system provided in this embodiment of the present disclosure; Figure 4 Experimental current waveforms of two modes of a coupling control method for a multi-coil transcranial magnetic stimulation system provided in this embodiment of the disclosure; Figure 5 The induced electric field distribution (5μs and 10μs) of a coupling control method for a multi-coil transcranial magnetic stimulation system provided in this embodiment of the present disclosure. Figure 6 The induced electric field distribution (15μs and 20μs) of a coupling control method for a multi-coil transcranial magnetic stimulation system provided in this embodiment of the present disclosure. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure are not intended to indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms are not intended to limit the quantity, but rather to indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0020] In the various figures, the same elements are represented by similar reference numerals. For clarity, not all parts in the figures are drawn to scale. Furthermore, some well-known parts may not be shown in the figures.

[0021] Many specific details of this disclosure, such as the structure, materials, dimensions, processing methods, and techniques of the components, are described below to provide a clearer understanding of the disclosure. However, as those skilled in the art will understand, this disclosure may be implemented without following these specific details.

[0022] To address the problems of electromagnetic coupling control and stimulation target switching in existing multi-coil systems, our laboratory designed a low-mutual-inductance three-coil system with an inner double coil and an outer single coil, based on spherical harmonic functions and inverse optimization methods. This system can achieve two stimulation modes: Mode 1 (shallow dual-target, approximately 1.3 cm deep) and Mode 2 (deep single-target, approximately 2.2 cm deep). Its fixed structure eliminates the need for frequent physical movement like traditional coils, providing convenient hardware conditions for stimulation mode switching. This invention focuses on the coupling system, establishing a mathematical model of the coupling circuit, and designing a control strategy based on the model that combines capacitor switching with capacitor voltage adjustment to address the challenge of multi-coil current synchronization control. The control strategy was verified through Simulink simulation, the synchronization of the current waveform after adjustment was evaluated using cosine similarity, and the method was validated through discharge experiments. Finally, the effective switching of stimulation modes under experimental current was verified using Comsol electromagnetic field simulation tools, providing theoretical and practical references for the development of multi-target transcranial magnetic stimulation technology.

[0023] like Figure 1 As shown, this embodiment of the invention provides a coupling control method for a multi-coil transcranial magnetic stimulation system, comprising: S1. Establish the coupled circuit model of the n-coil system. Each coil loop consists of a resistor, an inductor, a discharge capacitor, a diode, and a thyristor, where n is an integer greater than 2.

[0024] S2, determine the expected current relationship of each coil circuit according to the target stimulus pattern, and calculate the equivalent inductance of each coil circuit.

[0025] After n coil loops are coupled, the formula for calculating the equivalent inductance of the nth coil loop is as follows: ; Among them, L n I n Let be the self-inductance and expected current of the Nth coil loop, respectively; let Im be the expected current flowing through the mth coil loop; and let Mnm be the mutual inductance between the nth and mth coil loops.

[0026] Determine the expected current ratio of each coil based on the target stimulation pattern. .

[0027] S3: Dynamically adjust the discharge capacitor value of each coil circuit to make the damping angular frequency of each coil circuit consistent.

[0028] Damping angular frequency of each coil circuit The calculation formula is as follows: ; Among them, C n r n These are the discharge capacitance and resistance values ​​for the nth coil circuit, respectively.

[0029] The equivalent capacitance C of the nth coil loop n The following conditions must be met: ; Where k1 and k2 are preset error coefficients. The final objective is as follows: .

[0030] S4. Calculate the capacitor charging voltage based on the relationship between the equivalent inductance, the expected current, and the loop damping angular frequency.

[0031] The capacitor charging voltage U n The common terminal of the discharge capacitor and inductor applied to the nth coil circuit is given by the following formula: .

[0032] S5 controls all coil circuits to discharge synchronously, ensuring that the synchronization error of the current change rate is less than the preset value.

[0033] It should be noted that the technical solution disclosed herein does not impose any restrictions on the order of the above steps, that is, the execution order of each step can be arranged arbitrarily.

[0034] Taking a four-coil coil as an example, the parameters are adjusted as follows: ; (1) Target pattern: three shallow and one deep stimulation → Set the current ratio I1:I2:I3:I4 = 1:1:1:1.5; (2) Capacitor adjustment: Add a parallel capacitor to the I4 coil to increase C4; (3) Voltage compensation: U4 = 1.5 × U1 × (L e4 / L e1 ); The following is a detailed explanation using a three-coil circuit as an example. Based on Maxwell's equations, it is known that the induced electric field intensity (E) in the brain directly depends on the rate of change (di / dt) of the coil circuit current, as shown in formula (1); (1); Therefore, in order to accurately synthesize the target magnetic field and achieve the preset stimulation mode (Mode 1 or Mode 2), it is necessary to ensure that the rate of change of current (di / dt) of each coil circuit in the coupled state strictly maintains the specific proportional relationship required by the mode during the discharge process (Formula 2), that is, to maintain a specific current waveform with high synchronization. (2); In a multi-coil discharge system, each coil circuit discharges through a thyristor via a storage capacitor. Due to the very low line resistance, the circuit generates an underdamped sinusoidal pulse. Taking a 3-coil coupled system as an example... Figure 1 As shown, assuming all currents are sinusoidal waves with the same oscillation frequency, and the coil current is specified, the following matrix equation can be obtained from frequency domain analysis. (3); Solving for: (4); Where L is the self-inductance of the coil, ꞷ is the angular frequency of the sine wave, and M... nm It is coil L n and L m Mutual intuition between them, I n I m The current flows through coil L respectively n L m The current in the circuit, r is the line resistance including the coil resistance, r n It is the line resistance of the nth coil; (5); (6); U C Let i be the capacitor voltage. LLet Ln be the coil current. According to the derivation, after coupling, the coil inductance Ln becomes the equivalent inductance L. en Because the line resistance r is very small, To ensure the synchronization of the current, the angular frequency of each coil must be... As equal as possible, that is, let Try to keep them as consistent as possible. Because the self-inductance, expected current, and mutual inductance between each coil are different, The consistency is difficult to guarantee, but with the precise expression (6), this paper adopts the method of switching on and off the external capacitor and adjusting the capacitor voltage to ensure the current amplitude while making the angular frequency of the current of each coil as equal as possible, so as to ensure the synchronization of the waveform.

[0035] The measurement results of relevant parameters of the 3-coil system designed in this laboratory are shown in Table 1. The current magnitude given in Table 1 corresponds to the induced electric field strength at the stimulation target point of 100V / m. The equivalent inductance was calculated using equation (5). After analysis, the pulse duration in existing studies is generally within 200 μs. To avoid increasing system complexity due to excessive capacitance, two 420 μF capacitors and two 100 μF capacitors were selected. The capacitance values ​​and activation status corresponding to each discharge mode are shown in Table 2. In mode 1, when stimulating a shallow dual-target point, T1, T2, and T3 are turned on, and T4 is turned off. Coils 1, 2, and 3 discharge capacitors of 420 μF, 420 μF, and 100 μF, respectively. In mode 2, when stimulating a deep single-target point, T1, T2, T3, and T4 are turned on. Coils 1, 2, and 3 discharge capacitors of 420 μF, 420 μF, and 200 μF, respectively. In this configuration mode, the current frequencies of each coil are approximately equal (as shown in Table 3). By combining the above equation to calculate the capacitor voltage values ​​corresponding to the required current in different modes (as shown in Table 1) (as shown in Table 3), the required current synchronization can be maintained. The overall experimental circuit is as follows: Figure 2 As shown; To verify the effectiveness of the established mathematical model and operational strategy, a circuit simulation model was built in MATLAB 2024a Simulink, with all coils being 420μF capacitors and coupling ignored as a control group. Cosine similarity was used to measure the deviation between the simulated current waveform's rate of change and the expected rate of change. The specific calculation method is as follows: (11); (12); (13); The ratio of the expected current change rate is the ratio of the expected current amplitude, denoted by A; the change rate of the simulated current waveform is the reciprocal of the current expression with respect to time as shown in equation (13), denoted by B; before the current waveform reaches its peak, take 5 points evenly to calculate the average value of Similarity(A,B). The closer the average value is to 1, the closer the simulated current change rate is to the expected change rate, and the better the synchronization of the current waveform.

[0036] After the simulation, the actual circuit was built. Using the parameters in Table 3, the capacitor was charged using a high-voltage DC source. The switching of the four SKKH162 / 16E thyristors was controlled to switch modes. The current waveforms in different modes were recorded using an oscilloscope. The cosine similarity was calculated using the same method to evaluate the current synchronization.

[0037] The recorded current waveforms were used to simulate the target stimulation effects of Mode 1 and Mode 2 in COMSOL Multiphysics 6.2.

[0038] Based on simulation results Figure 3 and Figure 4 As shown, it can be intuitively seen that in different modes, the current waveforms of the three coils are all sinusoidal with approximately equal frequencies, and the current amplitudes also reach the expected values. Since the part with the largest current change rate is before the peak time, the maximum induced electric field can only be generated during this period. Therefore, we focus on the cosine similarity between the current waveform in the first 50μs and the expected current in Table 3. The cosine similarity of five points is sampled and averaged for comparison. The results are shown in Table 4. Obviously, the coupled control strategy results in higher waveform synchronization and is closer to the expected ratio. Due to limitations in experimental conditions, the existing current probes in the laboratory could not measure current waveforms reaching thousands of amperes. Therefore, a proportional reduction method was adopted, reducing the preset capacitor voltage by a factor of 100, and the current magnitude was also reduced by a factor of 100. After obtaining the experimental data with an oscilloscope, it was then magnified 100 times for analysis. Since the width of the sine pulse is only related to parameters such as capacitance, inductance, and current ratio, and is independent of the current magnitude, this operation would not affect the verification of the scheme. The results show that there are errors in the amplitude and frequency of the waveform compared to the simulation results. This is because of errors in line resistance, stray inductance, capacitor value, and mutual inductance measurement. The calculations are not precise, and factors such as the on-state voltage drop of thyristors mean that the actual experimental voltage needs to be about 1.5V higher than the theoretically calculated power supply, and the peak current is also difficult to match the expected value completely.

[0039] Based on the physical field modeling of the coils used, the induced electric field distribution under different modes of experimental current stimulation was plotted on a uniform spherical head model. Simulation analysis showed that the coupled control strategy achieved higher waveform synchronization and generated a larger induced electric field compared to the non-coupled control strategy. The highest values ​​for Mode 1 and Mode 2 were 109 V / m and 108 V / m, respectively, while the values ​​without coupling were only 104 V / m and 105 V / m. Due to the coupled control, the current synchronization was higher, and the corresponding current combination generated a smaller induced electric field intensity and stronger focusing in the surrounding non-target area. The stimulation depth of Mode 1 reached approximately 1.3 cm, and the stimulation depth of Mode 2 reached approximately 2.2 cm. The calculated circuit parameters can meet the target switching requirements and satisfy the activation requirements of neurons. Figure 5 and Figure 6 As shown.

[0040] This study proposes a coupled three-coil TMS mode switching mechanism based on thyristor topology switching and capacitor voltage regulation. For the first time, it achieves flexible switching between "shallow dual-target" (Mode1) and "deep single-target" (Mode2) stimulation modes through hardware reconfiguration. By activating specific thyristor combinations (e.g., adding a capacitor in parallel to Mode2 based on Mode1 to reduce the resonant frequency and ensure current synchronization), this method avoids the limitations of traditional methods that rely on physically moving coils to change the stimulation target. This design approach complements multi-focus TMS coil optimization (such as E-field control under current density constraints), providing a new path for switching in multi-mode, multi-coil coupled TMS systems.

[0041] The circuit coupling equations established based on frequency domain analysis reveal the dynamic relationship between mutual inductance and capacitor voltage and inductor current under coupling conditions, clarifying the physical mechanism for achieving current synchronization through capacitor switching and initial voltage setting. This theory provides analytical tools for the parameter design of coupled coil systems, such as matching the resonant frequency using the following formula: ; This solves the problem of current asynchrony in multi-coil coupling. This achievement is applicable not only to 3-coil systems but also to any multi-coil system.

[0042] Currently, only the dual-mode switching of 3 coils has been verified, and the position of the stimulation target and the current magnitude are fixed in the coil design. However, the operating principle of this system is universal and can be transferred to the dynamic adjustment of more targets and more coils. It is only necessary to calculate the number of capacitors switched on and off for a specific target and a specific coil, and configure the capacitor voltage.

[0043] This invention also provides a coupling control system for a multi-coil transcranial magnetic stimulation (TMS) system. The system can be used to implement the above-described coupling control method for the multi-coil TMS system. The system includes: The coil coupling module is configured to establish a coupling circuit model of an n-coil system. Each coil loop consists of a resistor, an inductor, a discharge capacitor, and a diode connected in series, where n is an integer greater than 2. The stimulation module is configured to determine the expected current of each coil circuit based on the target stimulation pattern and calculate the equivalent inductance of each coil circuit. The capacitance determination module is configured to dynamically adjust the discharge capacitance value of each coil circuit to ensure that the damping angular frequency of each coil circuit is consistent. The voltage compensation module is configured to calculate the capacitor charging voltage based on the relationship between the equivalent inductance, the expected current, and the loop damping angular frequency. The error adjustment module is configured to control the synchronous discharge of all coil circuits so that the synchronous error of the current change rate is less than a preset value.

[0044] This study successfully developed a coupled three-coil TMS mode switching system based on thyristor topology switching and capacitor voltage regulation. High-precision dual-mode stimulation was achieved through hardware reconstruction and frequency domain parameter matching. COMSOL simulation verified that Mode1 covers shallow dual targets and Mode2 focuses on deep single target, with an induced electric field >100V / m, meeting the needs of precision treatment for neuropsychiatric diseases and providing theoretical and hardware solutions for multi-target TMS.

[0045] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0046] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A coupling control method for a multi-coil transcranial magnetic stimulation system, characterized in that, include: S1. Establish a coupled circuit model of the n-coil system. Each coil loop consists of a resistor, an inductor, a discharge capacitor, a diode, and a thyristor, where n is an integer greater than 2. S2, determine the expected current relationship of each coil circuit according to the target stimulus pattern, and calculate the equivalent inductance of each coil circuit; S3; Dynamically adjust the discharge capacitor value of each coil circuit to make the damping angular frequency of each coil circuit consistent; S4. Calculate the capacitor charging voltage based on the relationship between the equivalent inductance, the expected current, and the loop damping angular frequency. S5 controls all coil circuits to discharge synchronously, ensuring that the synchronization error of the current change rate is less than the preset value.

2. The coupling control method for the multi-coil transcranial magnetic stimulation system according to claim 1, characterized in that, In S2, after the n coil loops are coupled, the formula for calculating the equivalent inductance of the nth coil loop is as follows: ； Among them, L n I n I represents the self-inductance and expected current of the Nth coil loop, respectively. m M is the expected current flowing through the m-th coil loop. nm Let be the mutual inductance between the nth coil loop and the mth coil loop.

3. The coupling control method for the multi-coil transcranial magnetic stimulation system according to claim 2, characterized in that, The damping angular frequency of each coil circuit in S3 The calculation formula is as follows: ； Among them, C n r n These are the discharge capacitance and resistance values ​​for the nth coil circuit, respectively.

4. The coupling control method for the multi-coil transcranial magnetic stimulation system according to claim 3, characterized in that, S4 specifically includes: The capacitor charging voltage U n The common terminal of the discharge capacitor and inductor applied to the nth coil circuit is given by the following formula: 。 5. The coupling control method for the multi-coil transcranial magnetic stimulation system according to claim 1, characterized in that, In step S3, the discharge capacitance value of each coil circuit is dynamically adjusted to ensure that the damping angular frequency of each coil circuit is consistent, ultimately obtaining the equivalent capacitance C of the nth coil circuit. n The following conditions must be met: ； Where k1 and k2 are both preset error coefficients.

6. The coupling control method for the multi-coil transcranial magnetic stimulation system according to claim 1, characterized in that, The formula for calculating the synchronization error ε of the current change rate in S5 is as follows: ； in, .

7. The coupling control method for the multi-coil transcranial magnetic stimulation system according to claim 1, characterized in that, S2 specifically includes: When n=4, the target stimulation pattern is three shallow and one deep stimulation. At this time, the expected currents of the first coil circuit, the second coil circuit, and the third coil circuit are the same and less than the expected current of the fourth coil circuit.

8. The coupling control method for the multi-coil transcranial magnetic stimulation system according to claim 7, characterized in that, S3 specifically includes: In the fourth coil circuit, a parallel capacitor is added to increase the discharge capacitance value.

9. A coupling control system for a multi-coil transcranial magnetic stimulation system, characterized in that, The system can be used to implement the coupling control method of the multi-coil transcranial magnetic stimulation system according to any one of claims 1 to 8, and the system includes: The coil coupling module is configured to establish a coupling circuit model of an n-coil system. Each coil loop consists of a resistor, an inductor, a discharge capacitor, a diode, and a thyristor, where n is an integer greater than 2. The stimulation module is configured to determine the expected current of each coil circuit based on the target stimulation pattern and calculate the equivalent inductance of each coil circuit. The capacitance determination module is configured to dynamically adjust the discharge capacitance value of each coil circuit to ensure that the damping angular frequency of each coil circuit is consistent. The voltage compensation module is configured to calculate the capacitor charging voltage based on the relationship between the equivalent inductance, the expected current, and the loop damping angular frequency. The error adjustment module is configured to control the synchronous discharge of all coil circuits so that the synchronous error of the current change rate is less than a preset value.

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