Transcranial magnetic stimulation circuit with adaptive shunt capability and control method

Abstract

The application discloses a transcranial magnetic stimulation circuit with self-adaptive parallel capability and a control method, comprising a stimulation coil and N energy storage sub-modules. Each energy storage sub-module comprises an energy storage capacitor, a power switch bridge arm and a unidirectional connection branch composed of unidirectional non-controlled power semiconductor devices. A plurality of energy storage sub-modules form a series energy storage structure according to a preset connection relationship in the excitation stage, and the high-voltage pulse is provided to the stimulation coil after the voltage of each energy storage capacitor is superposed; in the coil current decay stage, due to the reverse of the coil end voltage, the unidirectional non-controlled power semiconductor devices are naturally turned on according to the circuit state, so that the plurality of energy storage capacitors form a same-polarity parallel energy recovery path, and the equalization current is generated by using the voltage difference between the capacitors, so that the voltage deviation is reduced or the automatic equalization trend is realized. The application does not need to set a reconstruction switch for actively changing the connection relationship of the energy storage module, so that the system complexity is reduced and the reliability of the energy storage structure is improved.

Description

Technical Field

[0001] This invention relates to the field of transcranial magnetic stimulation (TMS) technology, specifically to a transcranial magnetic stimulation circuit and control method with adaptive parallel capability. Background Technology

[0002] Transcranial magnetic stimulation (TMS) pulse power supplies typically employ a pulse discharge circuit composed of an energy storage capacitor and a power switch. By controlling the conduction state of the energy storage unit and the power switch, the rapid establishment, maintenance, and decay of the stimulation coil current are achieved. To increase the stimulation intensity and reduce the withstand voltage requirement of individual power devices, multiple energy storage units are usually cascaded, and a higher excitation voltage is generated by superimposing the stored voltages.

[0003] In actual operation, the current in transcranial magnetic stimulation (TMS) coils exhibits a significant asymmetric variation. During the excitation phase, a higher voltage is required to rapidly establish the coil current; while during the energy release phase, only a lower amplitude reverse voltage is needed to maintain the current decay. Therefore, this type of stimulation process typically features "high-voltage excitation and low-voltage reverse decay," with the energy storage unit having different connection requirements at different stages.

[0004] Some existing cascaded energy storage structures employ active power switches to alter the connection relationships between energy storage units, enabling series output, parallel recovery, or voltage equalization. However, for the aforementioned asymmetric stimulation processes, the complete active series-parallel reconfiguration capability exhibits certain functional redundancy. Furthermore, the active reconfiguration method requires additional power switches and their driving isolation power supplies, as well as coordination of the commutation timing between multiple switches, thereby increasing system control complexity, the number of devices, and operating losses.

[0005] Furthermore, due to differences in energy storage capacitor parameters, switching losses, and inconsistent energy recovery paths, the voltage at the terminals of each energy storage capacitor may deviate during repeated stimulation. Using an additional voltage equalization converter or active voltage equalization branch would further increase the number of power devices and control complexity.

[0006] Therefore, for the fixed high-voltage excitation and low-voltage reverse attenuation working process in transcranial magnetic stimulation, there is a need for a transcranial magnetic stimulation circuit that does not require active changes to the connection relationship of the energy storage unit, can utilize the natural commutation characteristics during the current attenuation process of the stimulation coil, can enable unidirectional devices to automatically form parallel paths of the same polarity of the energy storage capacitor, and can achieve energy recovery and voltage balance. Summary of the Invention

[0007] The purpose of this invention is to provide a transcranial magnetic stimulation circuit and control method with adaptive parallel capability, which realizes energy recovery and voltage balancing, eliminates the need for a reconfiguration switch for actively changing the connection relationship of the energy storage module, reduces system complexity, and improves the reliability of the energy storage structure.

[0008] The technical solution to achieve the purpose of this invention is as follows:

[0009] A transcranial magnetic stimulation circuit with adaptive parallel capability includes a stimulation coil and N energy storage submodules SM1 to SM2 connected in sequence. N Where N≥2;

[0010] Each of the energy storage submodules includes an energy storage capacitor, a first bridge arm and a second bridge arm respectively connected to the two ends of the energy storage capacitor, and a unidirectional connection branch composed of unidirectional uncontrolled power semiconductor devices; the first bridge arm and the second bridge arm respectively include an upper bridge arm switch device and a lower bridge arm switch device connected in series.

[0011] The unidirectional connection branch is connected between the same polarity terminals of the energy storage capacitors in adjacent energy storage submodules to form a unidirectional connection path between the same polarity terminals of adjacent energy storage capacitors.

[0012] During the series excitation phase, by controlling the upper and lower bridge arm switching devices, the energy storage capacitors in each energy storage submodule are connected in series with the same effective polarity, and a first polarity voltage formed by the superposition of the voltages of each energy storage capacitor is applied to the stimulation coil.

[0013] During the coil current decay and energy recovery stage, by controlling the upper and lower bridge arm switching devices to form a freewheeling path, the unidirectional uncontrolled power semiconductor device is naturally turned on under the circuit bias effect of stimulating the coil current, so that the same polarity terminals of each energy storage capacitor form a common connection path, and multiple energy storage capacitors are connected in parallel with the same polarity.

[0014] Preferably, the unidirectional uncontrolled power semiconductor device is a power semiconductor device that can achieve unidirectional conduction without active control signal; the unidirectional uncontrolled power semiconductor device includes at least one of power diode, fast recovery diode, ultra-fast recovery diode, Schottky diode or silicon carbide Schottky diode; the unidirectional connection branch is determined by the power semiconductor device alone to determine the unidirectional conduction direction, and no active controllable switching device is provided for controlling the reverse conduction of the unidirectional connection branch.

[0015] Preferably, the stimulation coil has a head end and a tail end;

[0016] N energy storage submodules SM1 to SM N Connect sequentially from the first end to the last end;

[0017] One side of the first energy storage submodule SM1 is connected to the beginning of the stimulation coil, and the other side is connected to the second energy storage submodule SM2.

[0018] The Nth energy storage submodule SM N One side of the bridge arm connects to the (N-1)th energy storage submodule SM N－1 The other bridge arm connects to the tail end of the stimulation coil;

[0019] Intermediate Energy Storage Submodule SM k The two bridge arms are respectively connected to the adjacent energy storage submodules SM. k－1 and SM k＋1 , where 2≤k≤N-1.

[0020] Preferably, the energy storage submodule adopts a first submodule structure, specifically: the cathode of the unidirectional uncontrolled power semiconductor device is connected to the positive terminal of the energy storage capacitor of its respective energy storage submodule; for the k-th energy storage submodule SM k Where 1≤k<N, the anode of the unidirectional uncontrolled power semiconductor device is connected to the (k+1)th energy storage submodule SM. k+1 The positive terminal of the energy storage capacitor; the Nth energy storage submodule SM N The anode of the unidirectional uncontrolled power semiconductor device is connected to the tail end of the stimulation coil; multiple unidirectional uncontrolled power semiconductor devices together form a unidirectional common connection path between the positive terminals of the energy storage capacitor.

[0021] Preferably, the energy storage submodule adopts a second submodule structure; specifically, the anode of the unidirectional uncontrolled power semiconductor device is connected to the negative terminal of the energy storage capacitor of its respective energy storage submodule; for the k-th energy storage submodule SM k When 1≤k<N, the cathode of its unidirectional uncontrolled power semiconductor device is connected to the (k+1)th energy storage submodule SM. k+1 The negative terminal of the energy storage capacitor; the Nth energy storage submodule SM N The cathode of the unidirectional uncontrolled power semiconductor device is connected to the tail end of the stimulation coil; multiple unidirectional uncontrolled power semiconductor devices together form a unidirectional common connection path between the negative terminals of the energy storage capacitor.

[0022] Preferably, during the series excitation stage, the bridge arm switching devices in each energy storage submodule are controlled so that multiple energy storage capacitors form a series path with the same effective polarity, while the unidirectional uncontrolled power semiconductor devices connecting adjacent submodules are in the off state due to the reverse voltage.

[0023] The voltages at the terminals of multiple energy storage capacitors are superimposed to form a first polarity voltage, which is applied to the stimulation coil to achieve rapid establishment of coil current.

[0024] Preferably, during the coil current decay and energy recovery stage, the bridge arm switching devices in each energy storage submodule are controlled to establish a stimulation coil freewheeling path opposite to the first polarity voltage direction; the unidirectional uncontrolled power semiconductor device is naturally turned on under the circuit bias effect formed by the stimulation coil current, so that the same polarity terminals of each energy storage capacitor form a common connection path, and multiple energy storage capacitors are connected in parallel with the same polarity.

[0025] The parallel connection of the same polarity applies a second polarity voltage opposite to the first polarity voltage to the stimulation coil, causing the coil current to decay in the original direction and feeding the energy stored in the coil back to multiple energy storage capacitors. At the same time, the voltage difference between the terminals of the energy storage capacitors is used to achieve automatic voltage equalization.

[0026] A method for controlling a transcranial magnetic stimulation circuit includes:

[0027] Initial charging phase of energy storage capacitors: pre-charging multiple energy storage capacitors;

[0028] Series excitation stage: Control the bridge arm switching devices in each energy storage submodule to connect multiple energy storage capacitors in series with the same effective polarity, and apply the first polarity voltage to the stimulation coil;

[0029] Once the preset excitation termination condition is met, the first polarity voltage is removed, and a follow-through path is established after a preset dead time.

[0030] The voltage recovery stage of coil energy feedback, namely the coil current decay and energy recovery stage: the bias at both ends of the unidirectional uncontrolled power semiconductor device is changed by stimulating the coil current, so that it is naturally turned on, and multiple energy storage capacitors are connected in parallel with the same polarity. The parallel connection with the same polarity forms a second polarity voltage; the voltage recovery stage of coil energy feedback: when the preset freewheeling end condition is met, the freewheeling state is ended, and coil energy recovery and voltage equalization of energy storage capacitors are achieved through the parallel connection with the same polarity.

[0031] Furthermore, during the initial charging phase of the energy storage capacitor or the voltage recovery phase of the coil energy feedback, the process includes:

[0032] Control the bridge arm switching devices in each energy storage submodule to make multiple energy storage capacitors form a parallel connection of the same polarity;

[0033] The corresponding polarity terminals of each energy storage capacitor form a common connection node through the unidirectional connection branch and the bridge arm switching device. During the initial charging stage, the external charging power supply charges multiple energy storage capacitors simultaneously. During the coil energy feedback stage, the coil energy charges multiple energy storage capacitors simultaneously.

[0034] During the initial charging or voltage recovery phase, each energy storage capacitor naturally generates a balancing current through a unidirectional uncontrolled power semiconductor device based on its own terminal voltage difference, which gradually reduces the voltage deviation between the energy storage capacitors, eliminating the need for independent voltage detection and closed-loop voltage equalization control for each energy storage capacitor.

[0035] The energy storage capacitor charging and voltage equalization process does not require an additional voltage equalization circuit or an independent voltage equalization control unit.

[0036] Furthermore, the amplitude of the first polarity voltage is greater than the amplitude of the second polarity voltage; the preset excitation termination condition is determined based on at least one of the target coil current, stimulation intensity, stimulation pulse width, excitation time, and stimulation coil parameters; the preset freewheeling termination condition is determined based on at least one of the stimulation coil current drop threshold, freewheeling time, and maximum voltage deviation between the energy storage capacitor.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows: Multiple energy storage sub-modules designed in this invention form a series energy storage structure according to a preset connection relationship during the excitation stage. The voltages of each energy storage capacitor are superimposed to provide a high-voltage pulse to the stimulation coil. During the coil current decay stage, due to the reverse voltage at the coil terminals, the unidirectional uncontrolled power semiconductor device naturally conducts according to the circuit state, enabling multiple energy storage capacitors to form a parallel energy recovery path of the same polarity. The voltage difference between the capacitors generates a balancing current, achieving a reduction in voltage deviation or an automatic balancing trend. This invention utilizes the conduction characteristics of the unidirectional connection branch during the natural parallel process to achieve voltage balancing during energy recovery. Compared with solutions requiring an active voltage equalization circuit, this invention reduces additional power devices and control links, lowers system complexity, and improves system reliability. Attached Figure Description

[0038] Figure 1 This is a circuit diagram for a transcranial magnetic stimulation system with adaptive parallel capability.

[0039] Figure 2 These are two unidirectional submodule structure diagrams. Figure 2 Figure (a) shows a structure diagram of a positive extreme unidirectional submodule. Figure 2 Figure (b) shows a negative extreme unidirectional submodule structure.

[0040] Figure 3 This is a transcranial magnetic stimulation circuit composed of N positive-terminal unidirectional sub-modules.

[0041] Figure 4 This is a schematic diagram of the initial charging state of a capacitor in a transcranial magnetic stimulation circuit composed of four positive terminal unidirectional sub-modules.

[0042] Figure 5 The simulation results show the capacitor voltage and current of the transcranial magnetic stimulation circuit under the initial capacitor charging operating condition. Figure 5 (a) Simulation results of capacitor voltage in the transcranial magnetic stimulation circuit under capacitor charging operation state, which is composed of a structure with 4 positive terminal unidirectional sub-modules; Figure 5 (b) shows the simulation results of the capacitor current in the transcranial magnetic stimulation circuit under capacitor charging operation state, which is composed of four positive terminal unidirectional sub-modules.

[0043] Figure 6 This is a schematic diagram of the coil charging operation state in a naturally parallel transcranial magnetic stimulation circuit composed of four positive terminal unidirectional sub-modules.

[0044] Figure 7 This is a schematic diagram of the coil discharge operation state in a naturally parallel transcranial magnetic stimulation circuit composed of four positive terminal unidirectional sub-modules.

[0045] Figure 8 The coil voltage and coil current are measured under the charging and discharging conditions of a naturally parallel transcranial magnetic stimulation circuit consisting of four positive-terminal unidirectional sub-modules.

[0046] Figure 9 The simulation results show the voltage and current across the capacitors of the four sub-modules during the coil charging and discharging process. Figure 9 (a) shows the capacitor voltage of the naturally parallel transcranial magnetic stimulation circuit coil under charging and discharging conditions, which consists of four positive terminal unidirectional sub-modules. Figure 9 (b) shows the capacitive current of the transcranial magnetic stimulation circuit coil in its charging and discharging state, which is composed of four positive-terminal unidirectional sub-modules. Detailed Implementation

[0047] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the protection scope of the present invention.

[0048] like Figure 1 As shown, this embodiment provides a transcranial magnetic stimulation circuit with adaptive parallel capability, including a stimulation coil and N energy storage submodules SM1 to SM2 connected in sequence. N , where N≥2.

[0049] Each energy storage submodule includes an energy storage capacitor, a first bridge arm, a second bridge arm, and a unidirectional uncontrolled power semiconductor device. The first and second bridge arms are connected across the positive and negative terminals of the energy storage capacitor, respectively, and are used to change the energy transfer path between the energy storage capacitor and adjacent energy storage submodules by controlling the bridge arm switching devices.

[0050] The unidirectional uncontrolled power semiconductor devices constitute a unidirectional connection branch, including power diodes, fast recovery diodes, ultra-fast recovery diodes, or silicon carbide Schottky diodes, etc. The unidirectional connection branch connects the same polarity terminals of energy storage capacitors in adjacent energy storage submodules, forming a unidirectional common connection path between the same polarity terminals of the energy storage capacitors under specific operating conditions.

[0051] Specifically, such as Figure 2 As shown in (a), in the first embodiment, the cathode of the unidirectional uncontrolled power semiconductor device in each energy storage submodule is connected to the positive terminal of the corresponding energy storage capacitor, and the anode is connected to the positive terminal of the energy storage capacitor in the adjacent energy storage submodule. Thus, multiple unidirectional uncontrolled power semiconductor devices together constitute a unidirectional common connection path between the positive terminals of the energy storage capacitor, forming a unidirectional natural parallel structure of the positive terminals.

[0052] like Figure 2 As shown in (b), in the second embodiment, the anode of the unidirectional uncontrolled power semiconductor device in each energy storage submodule is connected to the negative terminal of the corresponding energy storage capacitor, and the cathode is connected to the negative terminal of the energy storage capacitor in the adjacent energy storage submodule. Thus, multiple unidirectional uncontrolled power semiconductor devices together constitute a unidirectional common connection path between the negative terminals of the energy storage capacitor, forming a unidirectional natural parallel structure of the negative terminals.

[0053] The two implementation methods described above are merely two mirrored implementations of a unidirectional connection branch. Both can automatically change their conduction state based on the voltage polarity across the unidirectional power semiconductor device under the action of the stimulating coil current, thereby achieving automatic connection between the same polarity terminals of the energy storage capacitor.

[0054] Taking the first implementation method as an example, multiple energy storage sub-modules are connected sequentially according to a preset connection direction to form a modular cascaded energy storage structure, such as... Figure 3 As shown.

[0055] Multiple energy storage submodules are connected sequentially according to a preset connection method to form a cascaded energy storage structure. The cascaded structure includes a stimulation coil and N energy storage submodules SM1 to SM2. N In this system, the midpoint of one bridge arm of the first-stage energy storage submodule SM1 is connected to the start end X1 of the stimulation coil, and the last-stage energy storage submodule SM... N One bridge arm's midpoint is connected to the end X2 of the stimulation coil. The midpoints of the bridge arms of the intermediate energy storage submodule are connected to the midpoints of the bridge arms of the two adjacent energy storage submodules. The anode of the unidirectional uncontrolled power semiconductor of the first-stage energy storage submodule SM1 is connected to the positive terminal of the capacitor of the second-stage energy storage submodule SM2. The anode of the unidirectional uncontrolled power semiconductor of the second-stage energy storage submodule SM2 is connected to the positive terminal of the capacitor of the third-stage energy storage submodule SM3, and so on. The Nth-stage energy storage submodule SM... NThe anode of the unidirectional uncontrolled power semiconductor is connected to the end X2 of the stimulation coil.

[0056] The internal structure of each energy storage submodule remains fixed, eliminating the need to change the connection relationship between the power devices within the module to achieve operational state transitions. In this structure, the bridge arm switching device is used to control the energy transfer path between the energy storage capacitor and the stimulation coil, and the unidirectional connection branches composed of unidirectional uncontrolled power semiconductors automatically change their conduction state according to the voltage polarity changes during operation.

[0057] Before the stimulation pulse is output, the energy storage capacitors in multiple energy storage submodules need to be charged. Taking the first embodiment as an example, four submodules are used, such as... Figure 4 As shown. During the initial charging phase before the generation of the stimulation pulse, or during the voltage recovery phase of coil energy feedback, the bridge arm switching devices in each energy storage submodule are controlled to connect multiple energy storage capacitors in parallel with the same polarity. At this time, the corresponding polarity terminals of each energy storage capacitor form a common connection path through a unidirectional connection branch, and the external charging power supply can simultaneously provide charging energy to multiple energy storage capacitors. Meanwhile, the stimulation coil is in a bypass state and does not participate in the capacitor charging process.

[0058] Figure 5 An 800V DC power supply is used to connect the capacitors of the fourth submodule, and a resistor is used to limit the current while charging the capacitors of the four submodules. Due to the initial voltage difference between the different energy storage capacitors, when the voltage of one energy storage capacitor is higher than the others, a unidirectional uncontrolled power semiconductor device is turned on under the influence of this voltage difference, generating an equalization current. This equalization current flows through the unidirectional connection branch to the low-voltage energy storage capacitors, causing a redistribution of energy among them. As the equalization process continues, the voltage difference between the energy storage capacitors gradually decreases, as shown in the figure. Figure 5 As shown in (a), the capacitor current in the naturally parallel transcranial magnetic stimulation circuit with four positive terminal unidirectional sub-modules in the capacitor charging working state is as follows: Figure 5 As shown in (b).

[0059] Therefore, this invention utilizes the naturally formed balanced current between energy storage capacitors to achieve a reduction in voltage deviation or an automatic balancing trend, without the need for setting up independent voltage equalization circuits or for independent voltage detection and closed-loop control of each energy storage capacitor.

[0060] During the excitation phase of the stimulation coil, by controlling the bridge arm switching devices in each energy storage submodule, multiple energy storage capacitors form an energy output path with the same effective polarity, such as... Figure 6 As shown.

[0061] Specifically, the bridge arm switching devices in each energy storage submodule are turned on according to their cascaded positions, creating a continuous current path between the energy storage capacitors. At this time, the voltages at the terminals of multiple energy storage capacitors are superimposed to form a first polarity voltage of 3200V, which is applied across the stimulation coil. Since the unidirectional connection branch is subjected to a reverse voltage at this time, the unidirectional power semiconductor devices are in the off state, which does not affect the series energy output of the energy storage capacitors. By superimposing the voltages of multiple energy storage capacitors, a high-amplitude excitation voltage can be formed across the stimulation coil, enabling rapid establishment of coil current.

[0062] After the excitation process of the stimulation coil ends, a freewheeling path is established by controlling the bridge arm switching device, such as... Figure 7 As shown. Because the stimulation coil has a continuous current characteristic, the coil current cannot change abruptly. Therefore, during the decay of the coil current, the voltage at the stimulation coil terminals changes in the opposite direction.

[0063] As the circuit state changes, the voltage polarity across the unidirectional connection branch changes. When the unidirectional power semiconductor device meets the forward conduction condition, it naturally conducts under the circuit bias caused by the stimulation coil current. This conduction process does not require an additional control signal.

[0064] After the unidirectional connection branch is activated, the same-polarity terminals of each energy storage capacitor form a common connection path, allowing multiple energy storage capacitors to be connected in parallel with the same polarity. At this time, the parallel energy storage capacitor group provides a second polarity voltage of -800V to the stimulation coil. Since the direction of the second polarity voltage is opposite to that of the first polarity voltage, it can maintain the coil current decaying in the original direction and reduce the rate of change of the coil current. Simultaneously, the magnetic field energy stored in the stimulation coil is fed back to the multiple energy storage capacitors through the parallel connection path.

[0065] During the energy recovery process, since the actual voltages of each energy storage capacitor may differ, a voltage difference will be generated between the energy storage capacitors connected in parallel.

[0066] For example, when the voltage of one energy storage capacitor is higher than that of the others, this capacitor provides a balancing current to the lower-voltage capacitors through a unidirectional connection branch. As energy is redistributed, the voltages at the terminals of each energy storage capacitor gradually converge. Therefore, this invention utilizes the conduction characteristics of the unidirectional connection branch during the natural parallel connection process to achieve voltage balancing during energy recovery. Compared to solutions that require additional active voltage equalization circuits, this invention reduces additional power devices and control circuits, thus improving system reliability.

[0067] In summary, the control method for the transcranial magnetic stimulation energy storage and equalization circuit of the present invention includes:

[0068] Initial charging phase of energy storage capacitors: Pre-charging of energy storage capacitors in multiple energy storage sub-modules;

[0069] Series excitation stage: Subsequently, control the bridge arm switching device to make multiple energy storage capacitors form an excitation path with the same effective polarity, and apply the first polarity voltage to the stimulation coil;

[0070] Once the preset excitation conditions are met, the first polarity voltage is removed, the state of the bridge arm switching devices is adjusted, and a coil freewheeling path is established.

[0071] The voltage recovery phase of coil energy feedback, i.e., the coil current decay and energy recovery phase, involves the change in voltage polarity across the unidirectional power semiconductor device caused by the coil current. This naturally conducts the unidirectional connection branch, causing multiple energy storage capacitors to form a parallel connection of the same polarity, which creates a second polarity voltage. Once the preset freewheeling termination condition is met, the freewheeling state ends, and coil energy recovery and voltage equalization of the energy storage capacitors are achieved through the parallel connection of the same polarity.

[0072] The initial charging phase of the energy storage capacitor or the voltage recovery phase of coil energy feedback includes:

[0073] Control the bridge arm switching devices in each energy storage submodule to make multiple energy storage capacitors form a parallel connection of the same polarity;

[0074] The corresponding polarity terminals of each energy storage capacitor form a common connection node through the unidirectional connection branch and the bridge arm switching device. In the initial charging stage, the external charging power supply charges multiple energy storage capacitors simultaneously. In the coil energy feedback stage, the coil energy charges multiple energy storage capacitors simultaneously.

[0075] During the charging process, each energy storage capacitor generates a balancing current through a unidirectional uncontrolled power semiconductor device based on its own terminal voltage difference, which gradually reduces the voltage deviation between the energy storage capacitors.

[0076] The amplitude of the first polarity voltage is greater than the amplitude of the second polarity voltage; the preset excitation termination condition is determined based on at least one of the target coil current, stimulation intensity, stimulation pulse width, excitation time, and stimulation coil parameters; the preset freewheeling termination condition is determined based on at least one of the stimulation coil current drop threshold, freewheeling time, and maximum voltage deviation between the energy storage capacitor.

[0077] according to Figure 6 and Figure 7 The control circuit was simulated, and the simulation results were obtained. Figure 8 and Figure 9 . Figure 8 A schematic diagram showing the voltage and current across the coil during charging and discharging demonstrates that this invention achieves a forward coil charging voltage of 3200V and a negative coil discharging voltage of 800V. Simultaneously, Figure 9The diagram shows the voltage and current on the capacitors of the four sub-modules during the charging and discharging process of the coil. The results show that when the coil is charged in the forward direction, all capacitors discharge uniformly, the unidirectional uncontrolled power diode is reverse cut off, the capacitor voltage is balanced and the discharge rate is consistent. When the coil is discharged in the reverse direction, the unidirectional uncontrolled power diode is forward turned on, there is a slight difference in the capacitor voltage, and the capacitor charging rate is different.

[0078] The above embodiments illustrate the basic working principle of the present invention. It should be noted that the core of the present invention lies in utilizing a unidirectional power semiconductor device to naturally change its conduction state according to the circuit state, thereby achieving a natural transition between series output and parallel recycling of energy storage capacitors of the same polarity, rather than relying on an additional active reconfiguration switch to change the energy storage structure.

Claims

1. A transcranial magnetic stimulation circuit with adaptive parallel capability, characterized in that, It includes a stimulation coil and N energy storage submodules SM1 to SM2 connected in sequence. N Where N≥2; Each of the energy storage submodules includes an energy storage capacitor, a first bridge arm and a second bridge arm respectively connected to the two ends of the energy storage capacitor, and a unidirectional connection branch composed of unidirectional uncontrolled power semiconductor devices; the first bridge arm and the second bridge arm respectively include an upper bridge arm switch device and a lower bridge arm switch device connected in series. The unidirectional connection branch is connected between the same polarity terminals of the energy storage capacitors in adjacent energy storage submodules to form a unidirectional connection path between the same polarity terminals of adjacent energy storage capacitors. During the series excitation phase, by controlling the upper and lower bridge arm switching devices, the energy storage capacitors in each energy storage submodule are connected in series with the same effective polarity, and a first polarity voltage formed by the superposition of the voltages of each energy storage capacitor is applied to the stimulation coil. During the coil current decay and energy recovery stage, by controlling the upper and lower bridge arm switching devices to form a freewheeling path, the unidirectional uncontrolled power semiconductor device is naturally turned on under the circuit bias effect of stimulating the coil current, so that the same polarity terminals of each energy storage capacitor form a common connection path, and multiple energy storage capacitors are connected in parallel with the same polarity.

2. The transcranial magnetic stimulation circuit with adaptive parallel capability according to claim 1, characterized in that, The unidirectional uncontrolled power semiconductor device includes at least one of a power diode, a fast recovery diode, an ultrafast recovery diode, a Schottky diode, or a silicon carbide Schottky diode; the unidirectional connection branch is determined solely by the power semiconductor device in terms of unidirectional conduction direction, and no active controllable switching device is provided for controlling the reverse conduction of the unidirectional connection branch.

3. A transcranial magnetic stimulation circuit with adaptive parallel capability according to claim 1, characterized in that, The stimulation coil has a head end and a tail end; N energy storage submodules SM1 to SM N Connect sequentially from the first end to the last end; One side of the first energy storage submodule SM1 is connected to the beginning of the stimulation coil, and the other side is connected to the second energy storage submodule SM2. The Nth energy storage submodule SM N One side of the bridge arm connects to the (N-1)th energy storage submodule SM N－1 The other bridge arm connects to the tail end of the stimulation coil; Intermediate Energy Storage Submodule SM k The two bridge arms are respectively connected to the adjacent energy storage submodules SM. k－1 and SM k＋1 , where 2≤k≤N-1.

4. A transcranial magnetic stimulation circuit with adaptive parallel capability according to claim 3, characterized in that, The energy storage submodule adopts a first submodule structure, specifically: the cathode of the unidirectional uncontrolled power semiconductor device is connected to the positive terminal of the energy storage capacitor of its respective energy storage submodule; for the k-th energy storage submodule SM k Where 1≤k<N, the anode of the unidirectional uncontrolled power semiconductor device is connected to the (k+1)th energy storage submodule SM. k+1 The positive terminal of the energy storage capacitor; the Nth energy storage submodule SM N The anode of the unidirectional uncontrolled power semiconductor device is connected to the tail end of the stimulation coil; multiple unidirectional uncontrolled power semiconductor devices together form a unidirectional common connection path between the positive terminals of the energy storage capacitor.

5. A transcranial magnetic stimulation circuit with adaptive parallel capability according to claim 3, characterized in that, The energy storage submodule adopts a second submodule structure; specifically, the anode of the unidirectional uncontrolled power semiconductor device is connected to the negative terminal of the energy storage capacitor of its respective energy storage submodule; for the k-th energy storage submodule SM k When 1≤k<N, the cathode of its unidirectional uncontrolled power semiconductor device is connected to the (k+1)th energy storage submodule SM. k+1 The negative terminal of the energy storage capacitor; the Nth energy storage submodule SM N The cathode of the unidirectional uncontrolled power semiconductor device is connected to the tail end of the stimulation coil; multiple unidirectional uncontrolled power semiconductor devices together form a unidirectional common connection path between the negative terminals of the energy storage capacitor.

6. A transcranial magnetic stimulation circuit with adaptive parallel capability according to claim 1, characterized in that, During the series excitation stage, the voltages at the terminals of multiple energy storage capacitors are superimposed to form a first polarity voltage, which is applied to the stimulation coil to establish a coil current.

7. A transcranial magnetic stimulation circuit with adaptive parallel capability according to claim 1, characterized in that, During the coil current decay and energy recovery stage, the parallel connection of the same polarity applies a second polarity voltage opposite to the first polarity voltage to the stimulation coil, causing the coil current to decay in the original direction and feeding back the energy stored in the coil to multiple energy storage capacitors. At the same time, automatic voltage equalization is achieved by utilizing the voltage difference between the terminals of the energy storage capacitors.

8. A control method based on the transcranial magnetic stimulation circuit according to any one of claims 1 to 7, characterized in that, include: Initial charging phase of energy storage capacitors: pre-charging multiple energy storage capacitors; Series excitation stage: Control the bridge arm switching devices in each energy storage submodule to connect multiple energy storage capacitors in series with the same effective polarity, and apply the first polarity voltage to the stimulation coil; Once the preset excitation termination condition is met, the first polarity voltage is removed, and a follow-through path is established after a preset dead time. The voltage recovery stage of coil energy feedback, namely the coil current decay and energy recovery stage: the bias at both ends of the unidirectional uncontrolled power semiconductor device is changed by stimulating the coil current, so that it is naturally turned on, and multiple energy storage capacitors are connected in parallel with the same polarity. The parallel connection with the same polarity forms a second polarity voltage; when the preset freewheeling end condition is met, the freewheeling state ends, and coil energy recovery and voltage equalization of energy storage capacitors are achieved through the parallel connection with the same polarity.

9. The control method according to claim 8, characterized in that, The initial charging phase of the energy storage capacitor or the voltage recovery phase of coil energy feedback includes: Control the bridge arm switching devices in each energy storage submodule to make multiple energy storage capacitors form a parallel connection of the same polarity; The corresponding polarity terminals of each energy storage capacitor form a common connection node through the unidirectional connection branch and the bridge arm switching device. During the initial charging stage, the external charging power supply charges multiple energy storage capacitors simultaneously, and during the coil energy feedback stage, the coil energy charges multiple energy storage capacitors simultaneously. During the initial charging or voltage recovery phase, each energy storage capacitor generates a balancing current through a unidirectional uncontrolled power semiconductor device based on its own terminal voltage difference, which gradually reduces the voltage deviation between the energy storage capacitors.

10. The control method according to claim 8, characterized in that, The amplitude of the first polarity voltage is greater than the amplitude of the second polarity voltage; the preset excitation termination condition is determined based on at least one of the target coil current, stimulation intensity, stimulation pulse width, excitation time, and stimulation coil parameters; the preset freewheeling termination condition is determined based on at least one of the stimulation coil current drop threshold, freewheeling time, and maximum voltage deviation between the energy storage capacitor.

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