A topological structure and control method of a modular multi-level transcranial magnetic stimulation generator

Abstract

The present invention discloses a topological structure and control method of a modular multi-stage transcranial magnetic stimulation generator, which belongs to the field of transcranial magnetic stimulation pulse generators, including a modular cascade full-bridge structure, a submodule parallel structure, a capacitor charging structure and a stimulation coil structure; the modular cascade full-bridge structure includes N submodules, the midpoints of the full-bridge bridge arms of each submodule are connected in series, and the midpoints of the bridge arms on both sides are connected to the stimulation coil structure; the submodule is composed of a storage capacitor and four full-bridge switch structures; the submodule parallel structure includes N-1 parallel structures, each parallel structure is divided into a full-bridge upper end parallel structure and a full-bridge lower end parallel structure; the capacitor charging structure includes a boost charging structure composed of a charging inductor, a charging control switch tube, a charging diode and a charging power supply, and an inductive freewheeling structure. The present invention can generate adjustable different pulse currents in the stimulation coil, thereby generating an induced electric field with adjustable parameters in the brain, thereby achieving a variety of different magnetic stimulation effects.

Description

Technical Field

[0001] The present invention relates to the field of transcranial magnetic stimulation pulse generators, and in particular to a topological structure and a control method of a modular multi-stage transcranial magnetic stimulation generator. Background Art

[0002] Transcranial Magnetic Stimulation (TMS) is a magnetic stimulation method for the brain nerves. During the TMS implementation process, a stimulation coil is placed near the target area of ​​the head, and a magnetic stimulation generator is used to generate a time-varying pulse current. When the current passes through the stimulation coil, a time-varying pulse magnetic field distributed in space is generated. The time-varying pulse magnetic field acts on the brain's nervous system to generate induced current, affecting brain metabolism and neural electrical activity, thereby causing a series of physiological and chemical reactions.

[0003] TMS is currently widely used in a variety of fields, including clinical diagnosis, treatment, and scientific research. In clinical diagnosis, TMS can be used to obtain motor evoked potential information and monitor the integrity and sensitivity of the nervous system. In clinical treatment, TMS can be applied to treat psychiatric disorders such as depression and schizophrenia. In rehabilitation, TMS can be used to achieve neurorehabilitation treatments for conditions such as stroke and Parkinson's disease.

[0004] The TMS stimulation effect is affected by the parameters of the magnetic pulse generator and the coil. Different parameters such as the pulse current amplitude, pulse width, pulse waveform, and the proportion of each phase of the pulse in the magnetic stimulation generator will lead to differences in the pulse current, which in turn leads to differences in the stimulation effect. At the same time, parameters such as the number of turns and coil arrangement in the stimulation coil will also lead to different distributions of the induced electric field in the brain, which in turn leads to differences in the stimulation effect. Most of the current transcranial magnetic stimulator generating circuits are resonant pulse circuits, which generate pulse currents based on the resonance of the coil inductance and the energy storage capacitor in the circuit. Therefore, the pulse waveform is almost unchangeable due to the limitations of the circuit topology and devices. However, studies have shown that the use of appropriate waveforms can significantly improve the efficacy of neuromodulation induced by repetitive magnetic stimulation.

[0005] Some researchers have proposed single-phase and biphasic pulse circuits, which primarily use thyristors as switching devices to generate single-phase or biphasic current pulses for stimulation. However, because these devices are semi-controlled, the circuits have limited adjustability and cannot meet diverse stimulation needs. Other researchers have proposed pulse parameter-controllable transcranial magnetic stimulation, which uses fully controlled switching devices to generate four-level voltage pulses, achieving a certain degree of waveform adjustability. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a topological structure and control method of a modular multi-level transcranial magnetic stimulation generator, which generates adjustable different pulse currents in the stimulation coil, and then generates an induced electric field with adjustable parameters such as pulse width, pulse amplitude, and duration of each pulse phase in the brain, thereby forming different magnetic stimulation effects.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a topological structure of a modular multi-level transcranial magnetic stimulation generator, including a modular cascaded full-bridge structure, a sub-module parallel structure, a capacitor charging structure and a stimulation coil structure; the modular cascaded full-bridge structure includes N sub-modules, the midpoints of the full-bridge arms of each sub-module are connected in series, and the midpoints of the bridge arms on both sides are connected to the stimulation coil structure; the sub-module is a full-bridge and capacitor structure, consisting of a storage capacitor and four full-bridge switch structures; the sub-module parallel structure includes N-1 parallel structures, each parallel structure is divided into a full-bridge upper end parallel structure and a full-bridge lower end parallel structure; the capacitor charging structure includes a boost charging structure and an inductive freewheeling structure; by controlling the discharge mode of the multi-level sub-module, discrete multi-level voltage pulses with controllable parameters can be generated, a variety of current waveforms are generated in the stimulation coil, and then an induced electric field with controllable pulse width, amplitude, and time parameters of each phase is generated, thereby achieving a variety of different magnetic stimulation effects.

[0008] A further improvement of the technical solution of the present invention is that: the modular cascade full-bridge structure includes N submodules: a first submodule SM1, a second submodule SM2, ..., an Nth submodule SM N The midpoint of the right bridge arm of the first submodule SM1 is connected to the midpoint of the left bridge arm of the second submodule SM2, the midpoint of the right bridge arm of the second submodule SM2 is connected to the midpoint of the left bridge arm of the third submodule SM3, ..., the N-1th submodule SM N-1 The midpoint of the right bridge arm and the Nth submodule SM N The midpoints of the left bridge arms are connected, the midpoints of the two adjacent bridge arms in the N submodules are connected to each other, and the left bridge arm midpoints of the first submodule SM1 and the Nth submodule SM N The midpoint of the right bridge arm is connected to the stimulation coil structure.

[0009] A further improvement of the technical solution of the present invention is that: each submodule includes a first full-bridge switch structure S1, a second full-bridge switch structure S2, a third full-bridge switch structure S3, a fourth full-bridge switch structure S4 and an energy storage capacitor C; wherein the source of the first full-bridge switch structure S1 is connected to the drain of the second full-bridge switch structure S2, and the first full-bridge switch structure S1 and the second full-bridge switch structure S2 constitute the left arm of the submodule full bridge; the source of the third full-bridge switch structure S3 is connected to the drain of the fourth full-bridge switch structure S4, and the third full-bridge switch structure S3 and the fourth full-bridge switch structure S4 constitute the right arm of the submodule full bridge; the source of the first full-bridge switch structure S1 and the drain of the second full-bridge switch structure S 2 drains are connected to form the center point of the left bridge arm; the source of the third full-bridge switch structure S3 and the drain of the fourth full-bridge switch structure S4 are connected to form the center point of the right bridge arm; the drain of the first full-bridge switch structure S1 is connected to the drain of the third full-bridge switch structure S3, forming the upper end of the full-bridge structure; the source of the second full-bridge switch structure S2 is connected to the source of the fourth full-bridge switch structure S4, forming the lower end of the full-bridge structure; the positive electrode of the energy storage capacitor C is connected to the drain of the first full-bridge switch structure S1 and the third full-bridge switch structure S3, and the negative electrode of the energy storage capacitor C is connected to the source of the second full-bridge switch structure S2 and the fourth full-bridge switch structure S4; the full-bridge switch structure is composed of multiple switch tubes connected in parallel, and the full-bridge switch structure S i (i∈{1,2,3,4}) includes the first parallel switch tube S i1 , the second parallel switch tube S i2 , ..., the kth parallel switch tube S ik k parallel switch tubes, wherein the first parallel switch tube S i1 , the second parallel switch tube S i2 , ..., the kth parallel switch tube S ik The sources and drains are connected to each other, forming a full-bridge switch structure.

[0010] A further improvement of the technical solution of the present invention is that: the upper end parallel structure of the full bridge is composed of an upper end parallel structure switch tube S p , an upper parallel structure diode D p And an upper parallel structure inductor L p The full-bridge lower parallel structure consists of a lower parallel structure switch tube S n and a lower parallel structure diode D n The upper end of the parallel structure switch tube S p The source is connected to the upper parallel structure diode D p Anode, upper parallel structure diode D p The cathode is connected to the upper parallel structure inductor L p , the lower parallel structure switch tube S n The source is connected to the lower parallel structure diode D nAnode; both ends of the parallel structure at the upper end of the full bridge are respectively connected to the upper ends of two adjacent sub-module full bridges, and both ends of the parallel structure at the lower end of the full bridge are respectively connected to the lower ends of two adjacent sub-module full bridges.

[0011] A further improvement of the technical solution of the present invention is that: the boost charging structure is composed of a charging inductor L c , the first charging control switch tube S c1 , the second charging control switch tube S c2 , charging diode D c and charging power supply U; the charging inductor L c One end is connected to the positive electrode of the charging power supply U, and the other end is connected to the first charging control switch tube S c1 The drain and the second charging control switch tube S c2 Drain, first charging control switch tube S c1 The source is connected to the power ground and the lower end of the adjacent submodule; the first charging control switch tube S c1 The drain and the second charging control switch tube S c2 Drain connection; second charging control switch tube S c2 The source is connected to the charging diode D c Anode; charging diode D c Connect the upper ends of adjacent submodules; the inductive freewheeling structure is composed of a freewheeling control thyristor SCR1 and a charging inductor L c Composition; wherein the anode of the freewheeling control thyristor SCR1 is connected to the second charging control switch tube S c2 Drain and charging inductance L c At the right end, the cathode of the freewheeling control thyristor SCR1 is connected to the positive electrode of the charging power supply U and the left end of the charging inductor.

[0012] A control method for the topological structure of a modular multi-level transcranial magnetic stimulation generator includes submodule energy storage capacitor charging control and submodule cascade discharge pulse control; the submodule energy storage capacitor charging control adopts dual closed-loop control of capacitor voltage and inductor current; the submodule cascade discharge pulse control includes nearest level approximation control, submodule level control, and submodule discharge power balance control.

[0013] A further improvement of the technical solution of the present invention is that the submodule energy storage capacitor charging control adopts capacitor voltage PI control plus inductor current model predictive control, and the specific steps are as follows:

[0014] Step 1: During the charging process, first turn on the second charging control switch tube S c2 , turning on the upper parallel structure switch tube S in the parallel structure of the adjacent sub-modules p And the lower parallel structure switch tube S n , so that the capacitors in each submodule are connected in parallel;

[0015] Step 2: Capacitor voltage given value U C * Subtract the actual value of the capacitor voltage U C Input to the PI controller, the PI controller output is used as the current inner loop given value I L * ;

[0016] Step 3: Current loop inductor current given value I L * Subtract the actual value of the inductor current I L Obtain the current error value and obtain the optimal control duty cycle D through the model predictive control algorithm. The duty cycle D is the first charging control switch tube S in the capacitor charging module. c1 Gate PWM wave duty cycle;

[0017] Step 4: After charging is completed, turn on the freewheeling control thyristor SCR1 to build an inductive freewheeling loop.

[0018] A further improvement of the technical solution of the present invention is that: the nearest level approximation control in the submodule cascade discharge pulse control is to divide the reference voltage by the capacitor voltage and then round it to obtain the required number of submodules that are effectively turned on; the submodule level control is to control the voltage output on both sides of the generated submodule. For each submodule, the first full-bridge switch structure S1 and the third full-bridge switch structure S3 are turned on, the submodule output is positive, and the output voltage is +U c , the second full-bridge switch structure S2 and the fourth full-bridge switch structure S4 are turned on, the submodule output is negative, and the output voltage is -U c , the first full-bridge switch structure S1, the second full-bridge switch structure S2 are turned on or the third full-bridge switch structure S3, the fourth full-bridge switch structure S4 are turned on, the sub-module is in bypass state, and its voltage output is 0; the sub-module discharge power balance control is to continuously detect the capacitor voltage U of each sub-module c1 、U c2 、U c3 ...U cN , according to the number of submodules effectively turned on obtained by the nearest level approximation control n sm , through the power balance control algorithm, the discharge submodules are continuously switched at a certain frequency, and the submodules with large capacitor voltage values ​​are preferentially selected for discharge to obtain the status f of each submodule sm1 、f sm2 、f sm3 ...f smN , achieving sub-module capacitance voltage balance and power balance.

[0019] Due to the adoption of the above technical solution, the technical advancements achieved by the present invention are:

[0020] 1. The present invention can generate different stimulation current waveforms and different induced induced electric fields by controlling the output of different numbers of sub-modules. The parameters such as pulse width, pulse amplitude, and duration of each pulse phase can be adjusted to achieve different magnetic stimulation effects.

[0021] 2. The present invention can meet the current scientific research requirements for pulse discharge circuit topology and achieve diversified stimulation. Due to the complex causes of mental disorders, the in-depth mechanism of TMS treatment of mental illnesses is still in the exploratory stage, and the stimulation waveform that brings the best stimulation effect has not been determined. Therefore, the circuit topology structure of the present invention can provide more possibilities for scientific research.

[0022] 3. The present invention adopts dual closed-loop control of inductor current and capacitor voltage, which can realize accurate capacitor charging. At the same time, the model prediction control value in the current inner loop can limit the inductor current to prevent excessive charging current.

[0023] 4. During the discharge pulse of the submodules, the power of each submodule can be balanced and the voltage can be kept basically consistent, thus preventing capacitor voltage imbalance between modules.

[0024] 5. The present invention adopts a modular design, which can change the number of sub-modules or adjust the capacitor voltage level of each sub-module during charging to meet different stimulation needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an electrical schematic diagram of the topological structure of a modular multi-stage transcranial magnetic stimulation generator provided by the present invention;

[0026] Figure 2 The present invention provides a submodule electrical schematic diagram of the topological structure of a modular multi-stage transcranial magnetic stimulation generator;

[0027] Figure 3 This is an electrical schematic diagram of a submodule full-bridge switch structure of a topology structure of a modular multi-level transcranial magnetic stimulation generator provided by the present invention;

[0028] Figure 4 This is a schematic diagram of a topological structure charging control method of a modular multi-level transcranial magnetic stimulation generator provided by the present invention;

[0029] Figure 5 This is a schematic diagram of a discharge control method for a topological structure of a modular multi-level transcranial magnetic stimulation generator provided by the present invention;

[0030] Figure 6 This is a switch tube control timing diagram of the topological structure of a modular multi-stage transcranial magnetic stimulation generator provided by the present invention;

[0031] Among them, U is the charging power supply, L cis the charging inductor, SCR1 is the freewheeling control thyristor, S c1 is the first charging control switch tube, S c2 D is the second charging control switch tube; c is a charging diode; N is the number of submodules, SM1 is the first submodule, SM2 is the second submodule, SM N is the Nth submodule; S1 is the first full-bridge switch structure in the submodule, S2 is the second full-bridge switch structure in the submodule, S3 is the third full-bridge switch structure in the submodule, and S4 is the fourth full-bridge switch structure in the submodule; S p(1) It is a parallel structure switch tube between the first submodule and the upper end of the second submodule full bridge, D p(1) L is a parallel structure diode between the upper ends of the full bridge of the first submodule and the second submodule. p(1) is the parallel structure inductance between the first submodule and the upper end of the second submodule full bridge, S n(1) It is a parallel structure switch tube between the lower end of the full bridge of the first submodule and the second submodule, D n(1) S is a parallel structure diode between the lower ends of the full bridge of the first submodule and the second submodule; p(2) D is the second parallel structure switch tube between the second submodule and the upper end of the third submodule full bridge. p(2) L is a parallel structure diode between the upper ends of the full bridge of the second submodule and the third submodule. p(2) is the parallel structure inductance between the second submodule and the upper end of the third submodule full bridge, S n(2) It is a parallel structure switch tube between the lower end of the full bridge of the second submodule and the third submodule, D n(2) S is a parallel structure diode between the lower ends of the full bridge of the second submodule and the third submodule. p(N-1) It is a parallel structure switch tube between the N-1th submodule and the upper end of the full bridge of the Nth submodule, D p(N-1) L is a parallel structure diode between the N-1th submodule and the upper end of the full bridge of the Nth submodule. p(N-1) is the parallel structure inductance between the N-1th submodule and the upper end of the full bridge of the Nth submodule, S n(N-1) It is a parallel structure switch tube between the N-1th submodule and the lower end of the full bridge of the Nth submodule, D n(N-1) It is a parallel structure diode between the N-1th submodule and the lower end of the full bridge of the Nth submodule. There are N submodules and N-1 parallel structures in the circuit topology; R coil is the coil parasitic resistance, L coil is the coil inductance; S i1 is the first parallel switch in the full-bridge switch structure i, S i2 is the second parallel switch in the full-bridge switch structure i, S i3 is the third parallel switch in the full-bridge switch structure i, S i4is the fourth parallel switch in the full-bridge switch structure i, S i5 is the fifth parallel switch in the full-bridge switch structure i, S ik is the kth parallel switch in the full-bridge switch structure i; U c * Set the voltage value for charging the capacitor, U c is the capacitor voltage value, I L * is the inductor current setting value, I L is the actual value of the inductor current, D is the charging switch tube S c1 The duty cycle value of the gate drive PWM signal; U ref is the voltage reference, n sm is the effective number of discharge submodules, U c1 、U c2 、U c3 ...U cN is the capacitor voltage value of each submodule, f sm1 、f sm2 、f sm3 ...f smN The status of each submodule. DETAILED DESCRIPTION

[0032] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0034] like Figure 1 As shown, a topology structure of a modular multi-level transcranial magnetic stimulation generator includes a modular cascade full-bridge structure, a sub-module parallel structure, a capacitor charging structure and a stimulation coil structure;

[0035] The modular cascade full-bridge structure includes N sub-modules, the midpoints of the full-bridge arms of each sub-module are connected in series, and the midpoints of the bridge arms on both sides are connected to the stimulation coil structure; the sub-module is a full-bridge and capacitor structure, consisting of a storage capacitor and four full-bridge switch structures;

[0036] The submodule parallel structure includes N-1 parallel structures, each parallel structure is divided into a full-bridge upper end parallel structure and a full-bridge lower end parallel structure;

[0037] The capacitor charging structure includes a boost charging structure and an inductive freewheeling structure;

[0038] The stimulation coil structure includes a coil parasitic resistance R coil and coil inductance L coil ; It is a conventional structure and belongs to the prior art, so the present invention will not describe it in detail.

[0039] By controlling the discharge mode of the multi-stage sub-modules, discrete multi-level voltage pulses with controllable parameters can be generated, and a variety of current waveforms can be generated in the stimulation coil, thereby generating an induced electric field with controllable parameters such as pulse width, amplitude, and phase time, thereby achieving a variety of different magnetic stimulation effects.

[0040] Furthermore, the modular cascade full-bridge structure includes a first submodule SM1, a second submodule SM2, ..., an Nth submodule SM N The submodule structure is a full-bridge and capacitor structure, wherein the midpoint of the right bridge arm of the first submodule SM1 is connected to the midpoint of the left bridge arm of the second submodule SM2, the midpoint of the right bridge arm of the second submodule SM2 is connected to the midpoint of the left bridge arm of the third submodule SM3, and the N-1 submodule SM N-1 The midpoint of the right bridge arm and the Nth submodule SM N The midpoints of the left bridge arms are connected, the midpoints of the two adjacent bridge arms in the N submodules are connected to each other, and the left bridge arm midpoints of the first submodule SM1 and the Nth submodule SM N The midpoint of the right bridge arm is connected to the stimulation coil structure.

[0041] Further, such as Figure 2As shown, the submodule consists of a full-bridge and capacitor structure. Each submodule includes four full-bridge switch structures: a first full-bridge switch structure S1, a second full-bridge switch structure S2, a third full-bridge switch structure S3, a first full-bridge switch structure S4 and a storage capacitor C. The source of the first full-bridge switch structure S1 is connected to the drain of the second full-bridge switch structure S2. The first full-bridge switch structure S1 and the second full-bridge switch structure S2 constitute the left arm of the submodule full bridge. The source of the third full-bridge switch structure S3 is connected to the drain of the fourth full-bridge switch structure S2. The drain of the switch structure S4 is connected to the drain of the first full-bridge switch structure S1, the third full-bridge switch structure S3, and the fourth full-bridge switch structure S4 constitute the right bridge arm of the sub-module full-bridge. The source of the first full-bridge switch structure S1 is connected to the drain of the second full-bridge switch structure S2 to form the center point of the left bridge arm. The source of the third full-bridge switch structure S3 is connected to the drain of the fourth full-bridge switch structure S4 to form the center point of the right bridge arm. The drain of the first full-bridge switch structure S1 is connected to the drain of the third full-bridge switch structure S3, and the source of the second full-bridge switch structure S2 is connected to the source of the fourth full-bridge switch structure S4. The positive electrode of the energy storage capacitor C is connected to the drains of the first full-bridge switch structure S1 and the third full-bridge switch structure S3, and the negative electrode of the energy storage capacitor C is connected to the sources of the second full-bridge switch structure S2 and the fourth full-bridge switch structure S4.

[0042] Further, such as Figure 3 As shown, the full-bridge switch structure consists of multiple switch tubes. i The first parallel switch tube S i1 , the second parallel switch tube S i2 , ..., the kth parallel switch tube S ik There are k switch tubes, the first parallel switch tube S i1 , the second parallel switch tube S i2 , ..., the kth parallel switch tube S ik The sources and drains of k equal switching tubes are connected to form a full-bridge switching structure.

[0043] Further, such as Figure 1 As shown, the boost charging structure consists of a charging inductor L c , the first charging control switch tube S c1 , the second charging control switch tube S c2 , charging diode D c And charging power supply U; Among them, the charging inductor L c One end is connected to the positive electrode of the charging power supply U, and the other end is connected to the first charging control switch tube S c1 The drain and the second charging control switch tube S c2 Drain, first charging control switch tube S c1 The source is connected to the power ground and the lower end of the adjacent sub-module full-bridge structure; the first charging control switch tube S c1 The drain and the second charging control switch tube S c2Drain connection; second charging control switch tube S c2 The source is connected to the charging diode D c Anode; charging diode D c Connect the upper ends of the full-bridge structure of adjacent sub-modules.

[0044] The inductor freewheeling structure is composed of freewheeling control thyristor SCR1 and charging inductor L c Composition; wherein the anode of the freewheeling control thyristor SCR1 is connected to the second charging control switch tube S c2 Drain and charging inductance L c At the right end, the cathode of the freewheeling control thyristor SCR1 is connected to the positive electrode of the charging power supply U and the left end of the charging inductor.

[0045] Furthermore, the module parallel structure is divided into two parts: the full-bridge upper end parallel structure and the full-bridge lower end parallel structure. The full-bridge upper end parallel structure consists of an upper end parallel structure switch tube S p (eg: S p(1) It is a parallel structure switch tube between the first submodule and the upper end of the second submodule full bridge, S p(2) It is the second parallel structure switch tube between the second submodule and the upper end of the third submodule full bridge, S p(N-1) A parallel structure switch tube is connected between the upper end of the full bridge of the N-1th submodule and the Nth submodule, and so on), and an upper end parallel structure diode D p (eg: D p(1) The diode D is a parallel structure between the upper ends of the full bridge of the first submodule and the second submodule. p(2) The diode D is connected in parallel between the upper ends of the full bridge of the second submodule and the third submodule. p(N-1) The parallel structure diode between the N-1th submodule and the upper end of the full bridge of the Nth submodule, and so on) and an upper end parallel structure inductor L p (eg: L p(1) L is the parallel structure inductance between the first submodule and the upper end of the second submodule full bridge, p(2) L is the parallel structure inductance between the second submodule and the upper end of the third submodule full bridge, p(N-1) The parallel structure inductor between the N-1th submodule and the Nth submodule full bridge upper end is connected in series, and so on. The parallel structure at the lower end of the full bridge is composed of a lower end parallel structure switch tube S n (eg: S n(1) It is a parallel structure switch tube between the first submodule and the upper end of the second submodule full bridge, S n(2) It is a parallel structure switch tube between the lower end of the full bridge of the second submodule and the third submodule, S p(N-1) The parallel structure switch tube between the upper end of the full bridge of the N-1th submodule and the Nth submodule, and so on) and a lower end parallel structure diode D n (eg: Dn(1) D is a parallel structure diode between the second submodule and the upper end of the full bridge of the nth submodule. n(2) D is a parallel structure diode between the lower ends of the full bridge of the second submodule and the third submodule. n(N-1) The parallel structure diodes between the N-1th submodule and the lower end of the full bridge of the Nth submodule, and so on) are connected in series, and the upper end parallel structure switch tube S p The source is connected to the upper parallel structure diode D p Anode, lower parallel structure switch tube S n The source is connected to the lower parallel structure diode D n The anode has two ends of the upper parallel structure connected to the upper ends of two adjacent submodules, and two ends of the lower parallel structure connected to the lower ends of two adjacent submodules.

[0046] A control method for the topological structure of a modular multi-level transcranial magnetic stimulation generator includes submodule energy storage capacitor charging control and submodule cascade discharge pulse control; the submodule energy storage capacitor charging control adopts dual closed-loop control of capacitor voltage and inductor current; the submodule cascade discharge pulse control includes nearest level approximation control, submodule level control, and submodule discharge power balance control.

[0047] Further, such as Figure 4 As shown in the figure, the method of submodule energy storage capacitor charging control is PI control plus model predictive control upper closed loop control. First, the capacitor voltage is given by value U C * Subtract the actual capacitor voltage value U C The output of the PI regulator is used as the current loop given value, and the current loop inductor current given value I L * Subtract the actual value of the inductor current I L Obtain the current error value and obtain the optimal control duty cycle D through the model predictive control algorithm. The duty cycle D is the first charging switch tube S in the capacitor charging module. c1 Gate drive PWM duty cycle.

[0048] Further, such as Figure 5 As shown in the figure, the nearest level approximation control in the submodule cascade discharge pulse control is to divide the reference voltage by the capacitor voltage and then round it to obtain the required submodule effective discharge quantity. The submodule discharge power balance control is to continuously detect the capacitor voltage U of each submodule. c1 、U c2 、U c3 ...U cN , according to the number of submodules effectively turned on obtained by the latest level control n sm, through the power balance control algorithm, the discharge submodules are continuously switched at a certain frequency, and the modules with large submodule capacitance voltage values ​​are preferentially selected for discharge to obtain the status f of each submodule. sm1 、f sm2 、f sm3 ...f smN , to achieve sub-module capacitor voltage balance and power balance.

[0049] like Figure 6 As shown, in the circuit charging phase, the first charging control switch tube S c1 The driving waveform is a high-frequency pulse waveform, and the second charging control switch tube S c2 Driven to high level, the second charge control switch tube S c2 Conducting, conducting the charging circuit; the upper parallel structure switch tube S p(1) 、S p(2) …S p(N-1) And the lower parallel structure switch tube S n(1) 、S n(2) …S n(N-1) During the discharge process, the first charging control switch tube S c1 Driven to low level, the second charge control switch tube S c2 Driven to low level, the charging circuit is closed; the upper parallel structure switch tube S p(1) 、S p(2) …S p(N-1) And the lower parallel structure switch tube S n(1) 、S n(2) …S n(N-1) Turn off, shut down the parallel circuit; at the same time, turn on the freewheeling control thyristor SCR1 to build an inductor freewheeling circuit to prevent the inductor from intermittently generating voltage pulses that damage the second charging control switch tube S c2 .

[0050] In summary, the modular multi-stage transcranial magnetic stimulation generator of the present invention constructs a cascade sub-module pulse discharge structure, and at the same time utilizes a sub-module parallel structure to realize the parallel connection of capacitors in the sub-modules. During the circuit charging process, the sub-module parallel structure is turned on, and the parallel capacitors are charged using the boost charging structure. During the discharge process, the sub-module parallel structure is turned off, and the sub-module cascade structure is used to discharge, generating a multi-level, controllable voltage pulse waveform. When a controllable voltage is applied to the coil structure, a variety of current waveforms are generated in the stimulation coil, thereby generating an induced electric field with controllable parameters such as pulse width, amplitude, and time of each phase, thereby achieving a variety of different magnetic stimulation effects to meet a variety of stimulation needs.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A topological structure of a modular multi-stage transcranial magnetic stimulation generator, characterized by: It includes a modular cascade full-bridge structure, a sub-module parallel structure, a capacitor charging structure and a stimulation coil structure; the modular cascade full-bridge structure includes N sub-modules, the midpoints of the full-bridge arms of each sub-module are connected in series, and the midpoints of the bridge arms on both sides are connected to the stimulation coil structure; the sub-module is a full-bridge and capacitor structure, consisting of a storage capacitor and four full-bridge switch structures; the sub-module parallel structure includes N-1 parallel structures, each parallel structure is divided into a full-bridge upper end parallel structure and a full-bridge lower end parallel structure; the capacitor charging structure includes a boost charging structure and an inductive freewheeling structure; by controlling the discharge mode of the multi-stage sub-module, discrete multi-level voltage pulses with controllable parameters can be generated, a variety of current waveforms are generated in the stimulation coil, and then an induced electric field with controllable pulse width, amplitude, and time parameters of each phase is generated, thereby achieving a variety of different magnetic stimulation effects; The modular cascade full-bridge structure includes N submodules: a first submodule SM1, a second submodule SM2, ..., an Nth submodule SM N The midpoint of the right bridge arm of the first submodule SM1 is connected to the midpoint of the left bridge arm of the second submodule SM2, the midpoint of the right bridge arm of the second submodule SM2 is connected to the midpoint of the left bridge arm of the third submodule SM3, ..., the N-1th submodule SM N-1 The midpoint of the right bridge arm and the Nth submodule SM N The midpoints of the left bridge arms are connected, the midpoints of the two adjacent bridge arms in the N submodules are connected to each other, and the left bridge arm midpoints of the first submodule SM1 and the Nth submodule SM N The midpoint of the right bridge arm is connected to the stimulation coil structure; The full-bridge upper parallel structure is composed of an upper parallel structure switch tube S p , an upper parallel structure diode D p And an upper parallel structure inductor L p The full-bridge lower parallel structure consists of a lower parallel structure switch tube S n and a lower parallel structure diode D n The upper end of the parallel structure switch tube S p The source is connected to the upper parallel structure diode D p Anode, upper parallel structure diode D p The cathode is connected to the upper parallel structure inductor L p , the lower parallel structure switch tube S n The source is connected to the lower parallel structure diode D n Anode; the two ends of the parallel structure at the upper end of the full bridge are respectively connected to the upper ends of the two adjacent sub-module full bridges, and the two ends of the parallel structure at the lower end of the full bridge are respectively connected to the lower ends of the two adjacent sub-module full bridges; The boost charging structure consists of a charging inductor L c , the first charging control switch tube S c1 , the second charging control switch tube S c2 , charging diode D c and charging power supply U; the charging inductor L c One end is connected to the positive electrode of the charging power supply U, and the other end is connected to the first charging control switch tube S c1 The drain and the second charging control switch tube S c2 Drain, first charging control switch tube S c1 The source is connected to the power ground and the lower end of the adjacent submodule; the first charging control switch tube S c1 The drain and the second charging control switch tube S c2 Drain connection; second charging control switch tube S c2 The source is connected to the charging diode D c Anode; charging diode D c Connect the upper ends of adjacent submodules; The inductor freewheeling structure is composed of freewheeling control thyristor SCR1 and charging inductor L c Composition; wherein the anode of the freewheeling control thyristor SCR1 is connected to the second charging control switch tube S c2 Drain and charging inductance L c At the right end, the cathode of the freewheeling control thyristor SCR1 is connected to the positive electrode of the charging power supply U and the left end of the charging inductor.

2. The topology of a modular multi-level transcranial magnetic stimulation generator according to claim 1, characterized in that: Each sub-module includes a first full-bridge switch structure S1, a second full-bridge switch structure S2, a third full-bridge switch structure S3, a fourth full-bridge switch structure S4 and an energy storage capacitor C; wherein the source of the first full-bridge switch structure S1 is connected to the drain of the second full-bridge switch structure S2, and the first full-bridge switch structure S1 and the second full-bridge switch structure S2 constitute the left arm of the sub-module full-bridge; the source of the third full-bridge switch structure S3 is connected to the drain of the fourth full-bridge switch structure S4, and the third full-bridge switch structure S3 and the fourth full-bridge switch structure S4 constitute the right arm of the sub-module full-bridge; the source of the first full-bridge switch structure S1 and the drain of the second full-bridge switch structure S2 are connected to form The center point of the left bridge arm; the source of the third full-bridge switch structure S3 and the drain of the fourth full-bridge switch structure S4 are connected to form the center point of the right bridge arm; the drain of the first full-bridge switch structure S1 is connected to the drain of the third full-bridge switch structure S3, forming the upper end of the full-bridge structure; the source of the second full-bridge switch structure S2 is connected to the source of the fourth full-bridge switch structure S4, forming the lower end of the full-bridge structure; the positive electrode of the energy storage capacitor C is connected to the drain of the first full-bridge switch structure S1 and the third full-bridge switch structure S3, and the negative electrode of the energy storage capacitor C is connected to the source of the second full-bridge switch structure S2 and the fourth full-bridge switch structure S4; the full-bridge switch structure is composed of multiple switch tubes connected in parallel, and the full-bridge switch structure S i In the example, i∈{1,2,3,4}, including the first parallel switch S i1 , the second parallel switch tube S i2 , ..., the kth parallel switch tube S ik k parallel switch tubes, wherein the first parallel switch tube S i1 , the second parallel switch tube S i2 , ..., the kth parallel switch tube S ik The sources and drains are connected to each other, forming a full-bridge switch structure.

3. A method for controlling the topology of a modular multi-level transcranial magnetic stimulation generator according to any one of claims 1 to 2, characterized in that: Including submodule energy storage capacitor charging control and submodule cascade discharge pulse control; The submodule energy storage capacitor charging control adopts dual closed-loop control of capacitor voltage and inductor current; the submodule cascade discharge pulse control includes nearest level approximation control, submodule level control and submodule discharge power balance control.

4. The method for controlling the topology of a modular multi-level transcranial magnetic stimulation generator according to claim 3, characterized in that: The submodule energy storage capacitor charging control adopts capacitor voltage PI control plus inductor current model predictive control. The specific steps are as follows: Step 1: During the charging process, first turn on the second charging control switch tube S c2 , turning on the upper parallel structure switch tube S in the parallel structure of the adjacent sub-modules p And the lower parallel structure switch tube S n , so that the capacitors in each submodule are connected in parallel; Step 2: Capacitor voltage given value U C * Subtract the actual value of the capacitor voltage U C Input to the PI controller, the PI controller output is used as the current inner loop given value I L * ; Step 3: Current loop inductor current given value I L * Subtract the actual value of the inductor current I L Obtain the current error value and obtain the optimal control duty cycle D through the model predictive control algorithm. The duty cycle D is the first charging control switch tube S in the capacitor charging module. c1 Gate PWM wave duty cycle; Step 4: After charging is completed, turn on the freewheeling control thyristor SCR1 to build an inductive freewheeling loop.

5. The method for controlling the topology of a modular multi-level transcranial magnetic stimulation generator according to claim 3, characterized in that: The nearest level approximation control in the submodule cascade discharge pulse control is to divide the reference voltage by the capacitor voltage and then round it up to obtain the required number of submodules that are effectively turned on; The submodule level control is to control the voltage output on both sides of the submodule. For each submodule, the first full-bridge switch structure S1 and the third full-bridge switch structure S3 are turned on, the submodule output is positive, and the output voltage is +U c , the second full-bridge switch structure S2 and the fourth full-bridge switch structure S4 are turned on, the submodule output is negative, and the output voltage is -U c , the first full-bridge switch structure S1, the second full-bridge switch structure S2 are turned on or the third full-bridge switch structure S3, the fourth full-bridge switch structure S4 are turned on, the sub-module is in bypass state, and its voltage output is 0; the sub-module discharge power balance control is to continuously detect the capacitor voltage U of each sub-module c1 、U c2 、U c3 ...U cN , according to the number of submodules effectively turned on obtained by the nearest level approximation control n sm , through the power balance control algorithm, the discharge submodules are continuously switched at a certain frequency, and the submodules with large capacitor voltage values ​​are preferentially selected for discharge to obtain the status f of each submodule sm1 、f sm2 、f sm3 …f smN , achieving sub-module capacitance voltage balance and power balance.

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