Omni-directional wireless energy transfer system for implantable / interventional medical devices

Abstract

An omnidirectional wireless energy transmission system for implantable / interventional medical devices comprises an omnidirectional wireless energy transmitting subsystem placed outside the body for generating an alternating rotating magnetic field with constant intensity and a wireless energy receiving subsystem for receiving wireless electric energy through electromagnetic induction, wherein the wireless energy receiving subsystem forwards the received wireless energy to the internal circuit of the implantable / interventional medical device. The present application adopts a three-dimensional energy transmitting coil and a single-dimensional energy receiving coil coupling structure, and a high-order LCC-S resonant compensation topology which is not sensitive to load changes, so as to ensure that the implantable / interventional medical device can obtain sufficient and stable energy supply at any position and posture in the working space, and improve the applicability of the wireless energy transmission system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless medical devices, and particularly to an omnidirectional wireless energy transmission system for implantable / interventional diagnosis and treatment devices. BACKGROUND

[0002] The existing implantable / interventional diagnosis and treatment device wireless energy transmission system based on the principle of magnetic coupling resonance usually adopts a one-dimensional transmitting coil and a three-dimensional orthogonal receiving coil electromagnetic coupling structure. The three-dimensional orthogonal receiving coil is located inside the implantable / interventional diagnosis and treatment device, and has a complex structure and is difficult to wind. At the same time, due to the narrow space inside the implantable / interventional diagnosis and treatment device, the size and the number of turns of the three-dimensional receiving coil are severely limited, resulting in a small coupling coefficient between the transmitting coil and the receiving coil, low energy transmission efficiency, small received energy, and other problems, which are difficult to meet the growing energy demand of implantable / interventional diagnosis and treatment devices. SUMMARY

[0003] The present application proposes an omnidirectional wireless energy transmission system for implantable / interventional diagnosis and treatment devices, which adopts a three-dimensional energy transmitting coil and a single-dimensional energy receiving coil coupling structure, and uses a high-order LCC-S resonance compensation topology that is not sensitive to load changes, so as to ensure that the implantable / interventional diagnosis and treatment device can obtain sufficient and stable energy supply at any position and posture in the working space, and improve the applicability of the wireless energy transmission system.

[0004] The present application is implemented by the following technical solutions:

[0005] The present application relates to an omnidirectional wireless energy transmission system for implantable / interventional diagnosis and treatment devices, which comprises an omnidirectional wireless energy transmitting subsystem for generating an alternating rotating magnetic field with constant intensity outside the body and a wireless energy receiving subsystem for receiving electric energy through electromagnetic induction. The wireless energy receiving subsystem forwards the received wireless energy to the internal circuit of the implantable / interventional diagnosis and treatment device.

[0006] The omnidirectional wireless energy transmitting subsystem comprises a phase-adjustable signal control unit, an LCC resonance compensation network, and a three-dimensional energy transmitting coil connected in sequence. The phase-adjustable signal control unit comprises a power supply module and control circuit module, drive circuit module, and inverter circuit module connected thereto respectively.

[0007] The wireless energy receiving subsystem comprises, in sequence, an energy receiving coil, a resonance compensation capacitor, a full-bridge rectification circuit module and a voltage stabilizing circuit module, wherein the resonance compensation capacitor and the energy receiving coil are connected in series to form a series resonance network; the full-bridge rectification module converts the alternating voltage induced by the receiving coil into a direct current voltage and outputs the direct current voltage to the voltage stabilizing circuit module; and the voltage stabilizing circuit module stabilizes the rectified voltage at a required value and outputs the voltage to the internal circuit of the implantable / interventional diagnosis and treatment device.

[0008] The three-dimensional energy transmitting coil comprises a pair of Helmholtz coils with their normal directions parallel to the axis direction of the cylindrical coil framework and two pairs of saddle coils with their normal directions perpendicular to the normal direction of the Helmholtz coils, wherein the Helmholtz coil as the innermost layer coil is wound on the cylindrical coil framework to generate a magnetic field in the z direction, the first pair of saddle coils is wound on the outer layer of the Helmholtz coil to generate a magnetic field in the y direction, the second pair of saddle coils is wound on the outer layer of the first pair of saddle coils to generate a magnetic field in the x direction, and the three pairs of coils are mutually orthogonal and decoupled and form a cylindrical structure.

[0009] Technical effects

[0010] The three-dimensional energy transmitting coil composed of a pair of Helmholtz coils and two pairs of saddle coils improves the internal working space, facilitates the entry and exit of the human body and covers the abdominal examination area of the human body, and is convenient for the clinical use of implantable / interventional diagnosis and treatment devices such as capsule endoscopes, magnetic capsule endoscopes and gastrointestinal micro robots for disease diagnosis and treatment; by adjusting the phase difference of the control signal, a uniform three-dimensional omnidirectional magnetic field is generated, which can cover all angles of the space at the same time, is simple to implement, does not require an additional coil current detection circuit, reduces the complexity of the system and enables the implantable / interventional diagnosis and treatment device to operate stably in different motion states. This method significantly improves the reliability and applicability of the wireless energy transmission system and meets the high requirements of implantable / interventional diagnosis and treatment devices for energy supply. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a schematic diagram of the system of the present application;

[0012] Figure 2 It is a schematic diagram of the inverter circuit control signal of the embodiment;

[0013] Figure 3 (a) and Figure 3 (b) are schematic diagrams of the three-dimensional energy transmitting coil structure;

[0014] Figure 4 (a) and Figure 4 (b) are time-varying diagrams of magnetic field strength and schematic diagrams of omnidirectional rotating magnetic field;

[0015] Figure 5 It is a principle block diagram of the phase difference optimization control strategy of the embodiment. DETAILED DESCRIPTION

[0016] As Figure 1 shown, the embodiment relates to an omnidirectional wireless energy transmission system for implantable / interventional medical devices, comprising: an omnidirectional wireless energy transmitting subsystem 1 placed outside the body for generating an alternating rotating magnetic field with constant intensity and a wireless energy receiving subsystem 2 for receiving wireless energy by electromagnetic induction, wherein: the wireless energy receiving subsystem 2 forwards the wireless energy to the internal circuit of the implantable / interventional medical device.

[0017] The omnidirectional wireless energy transmitting subsystem 1 comprises: a phase-adjustable signal control unit, an LCC resonance compensation network 105 and a three-dimensional energy transmitting coil 106 connected in sequence, wherein: the signal control unit generates three pairs of six-way PWM signals through internal programming, and provides the output three pairs of square wave signals to the LCC resonance compensation network 105 through a drive circuit and an inverter circuit, the LCC resonance compensation network 105 converts the input three pairs of square wave signals into three-phase sinusoidal alternating current signals through first-order LC filtering and second-order LC resonance, and the three-dimensional energy transmitting coil 106 flows through the three-phase sinusoidal alternating current signals to generate a three-dimensional alternating magnetic field.

[0018] In the three pairs of six-way PWM signals: the first group of control signals is defined as zero phase, and the phase difference α and β between the second group and the third group of signals are determined by a phase difference optimization control strategy.

[0019] The phase-adjustable signal control unit comprises: a power supply module 101 and control circuit module 102, drive circuit module 103 and inverter circuit module 104 connected thereto respectively, wherein: the control circuit module 102 generates initial three pairs of six-way PWM signals with phase difference according to the phase difference optimization control strategy and outputs to the drive circuit module 103; the drive circuit module 103 converts the initial three pairs of six-way PWM signals into control signals sufficient to drive the MOSFET in the inverter circuit module 104 to work normally; and the inverter circuit module 104 generates three-phase alternating current signals under the control of the three pairs of six-way control signals generated by the drive circuit module 103.

[0020] The phase difference optimization control strategy refers to: under the premise of satisfying and , the phase difference α and β are calculated, wherein: A and B are decomposition coefficients of the synthesized magnetic field intensity H in three-dimensional space, and A and B satisfy: K x and K yz are the proportional relationship between the magnetic field intensity generated by the Helmholtz coil 3, the saddle-shaped coil pair 4 and 5 and the current flowing into the coil, ω0 is the system operating angular frequency, and I m is the current amplitude flowing through the transmitting coil.

[0021] As Figure 5 shown, the phase difference optimization control strategy specifically includes:

[0022] Step 1) Select a suitable series compensation inductance Ls, construct LCC resonant compensation network 105, and connect the LCC resonant compensation network 105 with the inverter circuit module 104 and the three-dimensional energy transmitting coil 106.

[0023] Step 2) Set the DC supply voltage U dc of the inverter circuit, where the theoretical transmitting current is only related to the DC supply voltage U dc and the series compensation inductance Ls, and the decomposition coefficients A and B of the synthesized magnetic field strength H in the three-dimensional space are only related to the theoretical transmitting current, so that the control signal theoretical phase difference α and β are calculated by and .

[0024] Step 3) Test the receiving end receiving voltage when the three-dimensional energy transmitting coil works cooperatively, if it does not change with the receiving end attitude, the theoretical phase difference α and β calculated can generate a three-dimensional rotating spherical magnetic field, otherwise, test the Helmholtz coil 3, the pair of saddle coils 4 and the pair of saddle coils 5 in the three-dimensional energy transmitting coil 106 separately, calculate the actual transmitting current of the Helmholtz coil 3, the pair of saddle coils 4 and the pair of saddle coils 5 under the same working condition according to the output voltage of the full-bridge rectifier circuit module 203 in the wireless energy receiving subsystem 2, thereby updating the decomposition coefficients A and B of the synthesized magnetic field strength H in the three-dimensional space, and recalculating the phase difference α and β that can generate a rotating spherical magnetic field according to the formula in step 2.

[0025] Step 4) The control circuit module 102 generates three pairs of PWM signals corresponding to the phase difference, and inputs them into the three-dimensional energy transmitting coil 106, thereby generating an omnidirectional magnetic field.

[0026] The control signal sufficient to drive the MOSFET in the inverter circuit module 104 to work normally refers to the control signal with an amplitude higher than the MOSFET opening threshold voltage Ugs(th) generated by the TTL level PWM signal generated by the control circuit module 102 after being boosted by the driving circuit module 103.

[0027] The inverter circuit module 104 includes three groups of half-bridge circuits, each group of half-bridge circuit includes two MOSFETs, which are S1-S6 in sequence.

[0028] As Figure 2As shown, the control circuit module 102 outputs three pairs (S1 / S2, S3 / S4, S5 / S6) of six-way PWM signals, each pair of PWM signals is complementary and symmetrical, and after being driven by the driving circuit module 103, the six-way PWM signals are input into six MOSFETs of the inverter circuit module 104, so as to realize the switching control function of the MOSFETs.

[0029] As shown in Figure 1 As shown, the LCC resonant compensation network 105 includes three groups of series compensation inductors (Ls), parallel compensation capacitors (Cp) and coil series compensation capacitors (Cs), wherein: the series compensation inductor is a high-current power inductor, the parallel compensation capacitor is a high-temperature stability ceramic capacitor, and the coil series compensation capacitor is a high-frequency current-resistant high-voltage CBB capacitor.

[0030] As shown in Figure 1 As shown, the wireless energy receiving subsystem 2 includes energy receiving coils 201, resonant compensation capacitors 202, full-bridge rectifier circuit modules 203 and voltage stabilizing circuit modules 204 connected in sequence, wherein: the resonant compensation capacitors 202 and the energy receiving coils 201 are connected in series to form a series resonant network; the full-bridge rectifier module 203 converts the alternating voltage sensed by the receiving coil 201 into a direct current voltage, and outputs the direct current voltage to the voltage stabilizing circuit module 204, and the voltage stabilizing circuit module 204 stabilizes the rectified voltage at a required value and outputs the voltage to the internal circuit of the implantable / interventional diagnosis and treatment equipment.

[0031] The energy receiving coil 201 is a single-dimensional tightly wound coil, such as a single-dimensional hollow cylindrical coil, wound on a high magnetic permeability magnetic core.

[0032] The resonant compensation capacitor 202 is a high-temperature stability ceramic capacitor.

[0033] As shown in Figure 3 (a), the three-dimensional energy emitting coil 106 includes a pair of Helmholtz coils 3 arranged in parallel along the axis direction of the cylindrical coil skeleton and two pairs of saddle-shaped coil pairs 4 and 5 with the normal direction perpendicular to the normal direction of the Helmholtz coil, wherein: the Helmholtz coil 3 as the innermost layer coil is wound on the cylindrical coil skeleton to generate a z-direction magnetic field, the first saddle-shaped coil pair 4 is wound outside the Helmholtz coil 3 to generate a y-direction magnetic field, and the second saddle-shaped coil pair 5 is wound outside the saddle-shaped coil pair 4 to generate an x-direction magnetic field, and the three pairs of coils are mutually orthogonal and decoupled and form a cylindrical structure.

[0034] The three-dimensional energy emitting coil 106 is wound by using the same diameter of Litz wire.

[0035] As shown in Figure 3(b) shows, the first and second pairs of saddle coils 4, 5 are each composed of a saddle coil 6 and a saddle coil 7 arranged in opposition and connected in series, and they are wound in the same direction to generate a magnetic field in the same direction.

[0036] The two layers of coils in the first and second pairs of saddle coils 4, 5 are provided with insulating material.

[0037] Through specific experiments: the diameter of the cylindrical coil framework is 640 mm; the radius and spacing of the Helmholtz coils are both 320 mm, the length of the pair of saddle coils is 770 mm, the central angle is 150°, and the three groups of transmitting coils are each 30×2 turns; the receiving coil has a diameter of 15 mm, a length of 14 mm, is wound in three layers, and each layer has 120 turns; the load is 30 Ω; under the condition of a direct current supply voltage of 40 V, the receiving end can receive at least 532 mW of energy in any attitude, which can meet the energy requirements of implantable / interventional diagnosis and treatment equipment.

[0038] As shown in Figure 4 (a) shows the relationship between the amplitude of the magnetic field strength H at the center point of the three-dimensional energy transmitting coil 106 and time obtained by simulation calculation. By setting appropriate phase differences α and β, the theoretical synthesized magnetic field strength value is H0, and the simulation results show that the size of the synthesized magnetic field strength remains stable and does not change with time.

[0039] As shown in Figure 4 (b) shows the change trajectory of the synthesized magnetic field strength H vector at the center point of the three-dimensional energy transmitting coil 106 within one period of the excitation signal, which is a spherical surface in three-dimensional space, indicating that the magnetic field direction changes with time and can point to any direction on the spherical surface, i.e., the synthesized magnetic field sweeps through all angles of the spherical surface within one period. Therefore, regardless of the attitude of the single-dimensional energy receiving coil, the induced electromotive force remains unchanged, which can stably provide energy for implantable / interventional diagnosis and treatment equipment.

[0040] In actual application, due to the existence of coil resistance or not in a complete resonant state, the actual value of the current flowing into the Helmholtz coil 3, the pair of saddle coils 4 and the pair of saddle coils 5 may deviate from the theoretical value, so the phase difference α and β derived by theoretical calculation are not completely ideal three-dimensional rotating spherical magnetic fields, and further optimization of the phase difference of the control signal is required according to the feedback of the actual current value.

[0041] Direct measurement of the transmitting current flowing through the transmitting coil requires additional current detection circuit, and the induced electromotive force output by the energy receiving coil is proportional to the magnetic field strength generated by the transmitting coil, and the magnetic field strength is proportional to the transmitting current, therefore, the actual transmitting current can be calculated by detecting the voltage output by the energy receiving coil.

[0042] Compared with the prior art, the device adopts the coupling structure of three-dimensional energy transmitting coil and single-dimensional energy receiving coil. Three groups of phase-controllable control signals are input, and the three-dimensional energy transmitting coil can generate a uniform omnidirectional rotating magnetic field, so that the single-dimensional energy receiving coil can receive the same energy in any attitude at the same position, ensuring the stability of the received energy. The proposed PWM control signal phase difference optimization control strategy is simple and easy to implement, without additional current detection circuit, reducing the complexity of the system. The three-dimensional energy transmitting coil composed of a pair of Helmholtz coils and two pairs of saddle-shaped coils improves the internal working space to facilitate the entry and exit of the human body and covers the abdominal examination area of the human body, which is convenient for the clinical use of implant / interventional diagnosis and treatment equipment, such as capsule endoscopy, magnetic control capsule endoscopy, gastrointestinal micro-robot, etc. In addition, the omnidirectional wireless energy transmitting subsystem and the wireless energy receiving subsystem of the present application constitute an LCC-S resonant compensation structure, compared with the traditional S-S type compensation structure, the transmitting current of the transmitting end is controllable, and the receiving voltage of the receiving end does not change with the load, which is beneficial to the stable work of the implant / interventional diagnosis and treatment equipment in any working state.

[0043] The above specific implementation can be adjusted in different ways by those skilled in the art without departing from the principles and purposes of the present application, the protection scope of the present application is subject to the claims and is not limited by the above specific implementation, each implementation scheme within the scope is subject to the constraint of the present application.

Claims

1. An omnidirectional wireless energy transmission system for implantable / interventional diagnostic and treatment equipment, characterized in that: include: An omnidirectional wireless energy transmitting subsystem placed outside the body for generating an alternating rotating magnetic field of constant intensity and a wireless energy receiving subsystem for wirelessly receiving electrical energy through electromagnetic induction, wherein: the wireless energy receiving subsystem forwards the received wireless energy to the internal circuit of the implantable / interventional diagnostic and treatment device; The omnidirectional wireless energy transmission subsystem includes: a phase-adjustable signal control unit, an LCC resonance compensation network and a three-dimensional energy transmission coil connected in sequence; The three-dimensional energy transmitting coil comprises: a pair of Helmholtz coils whose normals are parallel to the axis of a cylindrical coil bobbin, and two pairs of saddle coils whose normals are perpendicular to the normals of the Helmholtz coils. The innermost Helmholtz coil is wound on the cylindrical coil bobbin to generate a magnetic field in the z-direction, the first saddle coil pair is wound on the outer layer of the Helmholtz coil to generate a magnetic field in the y-direction, and the second saddle coil pair is wound on the outer layer of the saddle coil to generate a magnetic field in the x-direction. The three pairs of coils are orthogonally decoupled and form a cylindrical structure. The signal control unit generates three pairs of six-channel PWM signals through internal programming, and provides the output three-way square wave signals to the LCC resonant compensation network through the drive circuit and the inverter circuit. The LCC resonant compensation network converts the input three-way square wave signals into three-phase sinusoidal AC signals through first-order LC filtering and second-order LC resonance. The three-phase sinusoidal AC signals flow through the three-dimensional energy transmitting coil, thereby generating a three-dimensional alternating magnetic field; In the three pairs of six PWM signals: the first group of control signals is defined as zero phase, and the phase differences α and β between the second and third groups of signals and the first group of control signals are determined by the phase difference optimization control strategy; The phase difference optimization control strategy is: as well as Under the premise of , the phase differences α and β are calculated, where A and B are the synthetic magnetic field strengths respectively. Decomposition coefficients in three-dimensional space, and A and B satisfy: , K x , K yz are the proportional relationship between the magnetic field strength generated by the Helmholtz coil and the saddle coil pair and the current flowing into the coil, is the system operating angular frequency, is the amplitude of the current flowing through the transmitting coil.

2. The omnidirectional wireless energy transmission system for implantable / interventional diagnostic and treatment equipment according to claim 1 is characterized in that: The phase-adjustable signal control unit includes: a power supply module and a control circuit module, a drive circuit module and an inverter circuit module respectively connected thereto, wherein: the control circuit module generates an initial three pairs of six PWM signals with a phase difference according to a phase difference optimization control strategy and outputs them to the drive circuit module; the drive circuit module converts the initial three pairs of six PWM signals into a control signal sufficient to drive the MOSFET in the inverter circuit module to work normally, that is, the TTL-level PWM signal generated by the control circuit module is boosted by the drive circuit module to generate a control signal with an amplitude higher than the MOSFET turn-on threshold voltage Ugs(th); the inverter circuit module generates a three-phase AC signal under the control of the three pairs of six control signals generated by the drive circuit module.

3. The omnidirectional wireless energy transmission system for implantable / interventional diagnostic and treatment equipment according to claim 2 is characterized in that: The phase difference optimization control strategy specifically includes: Step 1) Selecting a suitable series compensation inductor Ls, constructing an LCC resonant compensation network, and connecting the LCC resonant compensation network to the inverter circuit module and the three-dimensional energy transmitting coil; Step 2) Set the DC supply voltage U of the inverter circuit dc , where the theoretical emission current is only related to the DC supply voltage U dc is related to the series compensation inductance Ls, while the decomposition coefficients A and B of the synthetic magnetic field intensity H in three-dimensional space are only related to the theoretical emission current, thus: as well as , calculate the theoretical phase differences α and β of the control signals; Step 3) Testing the received voltage at the receiving end when the three-dimensional energy transmitting coils work in coordination. If the voltage does not change with the receiving end's posture, the calculated theoretical phase differences α and β can generate a three-dimensional rotating spherical magnetic field. Conversely, the Helmholtz coil and the first and second saddle coils in the three-dimensional energy transmitting coils are tested separately. The actual transmitting current of the Helmholtz coil and the first and second saddle coils under the same operating conditions is calculated based on the output voltage of the full-bridge rectifier circuit module in the wireless energy receiving subsystem. Based on this, the decomposition coefficients A and B of the composite magnetic field intensity H in three-dimensional space are updated. The phase differences α and β that can generate a rotating spherical magnetic field are recalculated using the formula in step 2. Step 4) The control circuit module generates three pairs of PWM signals with corresponding phase differences and inputs them into the three-dimensional energy transmitting coil to generate an omnidirectional magnetic field.

4. The omnidirectional wireless energy transmission system for implantable / interventional diagnostic and treatment equipment according to claim 3 is characterized in that: The inverter circuit module includes three groups of half-bridge circuits, each group of half-bridge circuits includes two MOSFETs; The control circuit module outputs three pairs of six PWM signals, each pair of PWM signals is complementary and symmetrical, and is driven by the drive circuit module and input into the six MOSFETs of the inverter circuit module respectively to realize the switching control of the MOSFETs; The LCC resonant compensation network includes: three groups of series compensation inductors (Ls), parallel compensation capacitors (Cp) and coil series compensation capacitors (Cs), wherein: the series compensation inductors are power inductors with high current resistance, the parallel compensation capacitors are ceramic capacitors with high temperature stability, and the coil series compensation capacitors use high-voltage CBB capacitors that can withstand high-frequency current.

5. The omnidirectional wireless energy transmission system for implantable / interventional diagnostic and treatment equipment according to claim 1 is characterized in that: The wireless energy receiving subsystem includes: an energy receiving coil, a resonant compensation capacitor, a full-bridge rectifier circuit module and a voltage stabilizing circuit module connected in sequence, wherein: the resonant compensation capacitor and the energy receiving coil are connected in series to form a series resonant network; the full-bridge rectifier circuit module converts the AC voltage sensed by the receiving coil into a DC voltage and outputs it to the voltage stabilizing circuit module. The voltage stabilizing circuit module stabilizes the rectified voltage at the required value and outputs it to the internal circuit of the implantable / interventional diagnostic and treatment equipment.

6. The omnidirectional wireless energy transmission system for implantable / interventional diagnostic and treatment equipment according to claim 1 is characterized in that: The three-dimensional energy emitting coils are all wound with Litz wires of the same wire diameter. The first and second saddle coil pairs are both composed of saddle coils arranged opposite to each other and connected in series, and they are wound in the same direction to generate a magnetic field in the same direction.

7. The omnidirectional wireless energy transmission system for implantable / interventional diagnostic and treatment equipment according to claim 6, characterized in that: Insulating material is provided between the two layers of coils in the first and second saddle-shaped coil pairs.

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