Ultrasonic scalpel system phase locking method and ultrasonic scalpel system

Abstract

The present invention provides an ultrasonic knife system phase-locking method and an ultrasonic knife system, wherein the ultrasonic knife system comprises a connected ultrasonic knife, a transducer and a generator, and the method comprises the following steps: the generator generates an initial current signal, which is sent to the transducer as the current working signal of the ultrasonic knife; the voltage value and the current value of the main circuit in the ultrasonic knife equivalent circuit are measured; the voltage effective value, the current effective value and the voltage-current phase difference of the main circuit are calculated; the voltage value, the current value and the voltage-current phase difference of the second branch are calculated; the generator is controlled to generate a current signal at a new frequency as the current working signal of the ultrasonic knife, which is sent to the transducer to drive the ultrasonic knife to work, and the process is repeated. Compared with the method in which the traditional ultrasonic equipment needs to be equipped with a tuning inductor matching the system frequency, the ultrasonic system phase-locking method of the present invention does not need to limit the ultrasonic frequency and has good versatility.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic scalpels, and in particular to an ultrasonic scalpel system phase locking method and an ultrasonic scalpel system. Background Art

[0002] Ultrasonic scalpel is a widely used surgical instrument for tissue cutting and coagulation hemostasis in surgical operations. The method of achieving this is to convert electrical signals into ultrasonic signals through a transducer and then transmit them to the tip of the scalpel, so that the tip of the scalpel generates high-frequency vibrations (for example, 55,500 times), denaturing proteins in the tissue at the tip of the scalpel to form a viscous coagulant, through which a hemostatic seal is formed. The accuracy of cutting and coagulation is controlled by the surgeon's skills and the adjustment of power level, blade, tissue traction and scalpel pressure.

[0003] The ultrasonic knife system is mainly composed of a generator, a transducer and an ultrasonic knife head. Figure 1 The figure shows a schematic diagram of an ultrasonic knife system, including a transducer 11, an ultrasonic knife head housing 12, an ultrasonic knife head sleeve 13, an ultrasonic knife rod 14, etc. The ultrasonic knife rod 14 is coupled to the transducer 11 inside the ultrasonic knife head sleeve 13, and the transducer 11 is connected to the generator through a cable 15.

[0004] In general, the ultrasonic knife system can be equivalent to an equivalent circuit with a main circuit, a first branch circuit, and a second "dynamic" branch circuit, such as Figure 2 As shown. The first branch is mainly the static capacitance C0, which is a parasitic parameter of the ultrasonic knife handle. The second "dynamic" branch includes an inductor L1, a resistor R1 and a capacitor C1 connected in series, and the inductor L1, the resistor R1 and the capacitor C1 are the electromechanical properties of the main part of the ultrasonic knife. The generator of a conventional ultrasonic knife introduces a tuning inductor Ls on the main line, and the tuning inductor Ls is used to detune the static capacitance at the resonant frequency, so that basically all current outputs of the generator flow into the second "dynamic" branch. Therefore, the actually measured voltage, current, and voltage-current phase difference parameters are the parameters of the second "dynamic" branch, and the generator controls the frequency drive output to make the transducer of the ultrasonic knife at the resonant frequency. The tuning inductor Ls also converts the phase impedance diagram of the transducer of the ultrasonic knife to improve the frequency locking capability of the generator.

[0005] However, the tuning inductor Ls must match the specific static capacitance of the ultrasonic scalpel transducer. Different ultrasonic scalpel transducers with different static capacitances require different tuning inductors. This means that an ultrasonic scalpel system can only use one type of ultrasonic scalpel, and its versatility is poor. This patent application is to solve this problem and provide an ultrasonic scalpel phase-locking method and ultrasonic scalpel system that can control the frequency without a tuning inductor. Summary of the invention

[0006] In view of the shortcomings of the current prior art, an object of the present invention is to provide an ultrasonic knife system phase locking method and an ultrasonic knife system with better versatility.

[0007] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0008] A phase locking method for an ultrasonic scalpel system, the ultrasonic scalpel system comprising an ultrasonic scalpel, a transducer and a generator connected to each other, the method comprising the following steps:

[0009] Step S1, the generator generates an initial current signal and sends it to the transducer as the current working signal of the ultrasonic knife;

[0010] Step S2, measuring and obtaining the voltage value and current value of the main circuit in the ultrasonic scalpel equivalent circuit, wherein the ultrasonic scalpel equivalent circuit comprises a main circuit and a first branch circuit and a second branch circuit connected in parallel with the main circuit, wherein the main circuit is the generator directly connected to the ultrasonic scalpel and does not have a tuning inductor, and the ultrasonic scalpel comprises a connected ultrasonic scalpel handle and an ultrasonic scalpel body, wherein the first branch circuit is the parasitic static capacitance of the ultrasonic scalpel handle, and the second branch circuit comprises a first inductor, a first resistor and a first capacitor connected in series, which are the electromechanical properties of the ultrasonic scalpel body;

[0011] Step S3, calculating the voltage effective value, current effective value, and voltage-current phase difference of the trunk circuit according to the voltage value and current value of the trunk circuit;

[0012] Step S4, calculating the voltage value, current value, and voltage-current phase difference of the second branch according to the voltage effective value, current effective value, voltage-current phase difference, and vector diagram of the main circuit;

[0013] Step S5, according to the voltage value, current value and voltage-current phase difference of the second branch, control the generator to generate a current signal at a new frequency as the current working signal of the ultrasonic knife, send it to the transducer to drive the ultrasonic knife to work, and return to step S2 to loop.

[0014] Furthermore, in step S1, the frequency of the initial current signal is far away from the resonance point.

[0015] Furthermore, in step S2, the voltage value and current value of the main circuit in the ultrasonic knife equivalent circuit are measured and obtained by ADC sampling according to the sampling frequency.

[0016] Furthermore, the sampling frequency is dynamically adjusted according to the frequency of the current working signal of the ultrasonic knife.

[0017] Further, in step S3, the voltage effective value, current effective value, and voltage-current phase difference of the trunk line are calculated based on the voltage value and current value of the trunk line, and the voltage effective value and current effective value of the trunk line are calculated by fast Fourier transform. After the voltage effective value and current effective value of the trunk line are calculated, the voltage-current phase difference is obtained by detecting the zero-crossing moment based on the voltage effective value and current effective value of the trunk line.

[0018] Further, in step S4, the voltage value, current value, and voltage-current phase difference of the second branch are calculated according to the voltage effective value, current effective value, voltage-current phase difference, and vector diagram of the main circuit, including:

[0019] U 1 =U;

[0020]

[0021]

[0022] Among them, U 1 is the voltage value of the second branch, U is the effective value of the voltage of the main line, I 1 is the current value of the second branch, I is the effective value of the current of the main circuit, θ 1 is the voltage-current phase difference of the second branch, θ is the voltage-current phase difference of the main line, C 0 is the parasitic static capacitance of the ultrasonic knife handle in the first branch.

[0023] Further, in step S5, the generator is controlled to generate a current signal at a new frequency as the current working signal of the ultrasonic knife according to the voltage value, current value, and voltage-current phase difference of the second branch, and the frequency change is calculated according to the first resistance, the first capacitance, the first inductance of the second branch, and the difference between the voltage-current phase difference of the second branch and the target phase difference, including:

[0024]

[0025]

[0026]

[0027] θ′(ω) is positive; or

[0028]

[0029] θ′(ω) is negative;

[0030] Among them, f Δ is the frequency change, θ 1is the phase difference of the voltage and current of the second branch, ω is the angular frequency, ω=2πf, f is the frequency of the current working signal, k is the proportional coefficient, which is set according to the actual situation, θ′)ω) is the derivative of the phase difference of the voltage and current of the second branch with respect to the angular frequency ω, m is an intermediate variable used to simplify the formula and has no practical meaning, ω s is the preset fixed frequency, θ′(ω s ) is the second branch voltage and current phase difference to the preset fixed frequency ω s The derivative of is the same as the formula of θ′(ω);

[0031] Then, a current signal at a new frequency is generated according to the frequency change amount and the frequency of the current working signal as the current working signal of the ultrasonic knife.

[0032] Further, in step S5, the generator is controlled to generate a current signal at a new frequency as the current working signal of the ultrasonic scalpel according to the voltage value, current value and voltage-current phase difference of the second branch. The second branch series resonant frequency is directly calculated according to the voltage value, current value and voltage-current phase difference of the second branch as the current working signal of the ultrasonic scalpel, and then the frequency of the current signal of the generator is controlled to directly reach the resonant frequency.

[0033] Further, in step S1, the initial current signal is an initial current sinusoidal signal that generates a specific frequency and amplitude and an arbitrary phase;

[0034] The method further comprises:

[0035] Step S6, after the shearing is completed, the current output is turned off.

[0036] The present invention also discloses an ultrasonic knife system, which includes a connected ultrasonic knife, a transducer and a generator. The generator uses the ultrasonic knife system phase-locking method as described above to generate a current signal and send it to the transducer as the current working signal of the ultrasonic knife.

[0037] The ultrasonic knife system phase-locking method and ultrasonic knife system of the present invention first measure the voltage value and current value of the main circuit in the ultrasonic knife equivalent circuit, then calculate the voltage value, current value and voltage-current phase difference of the branch circuit according to the voltage value and current value of the main circuit, and then generate a new frequency signal according to the voltage value, current value and voltage-current phase difference of the branch circuit to work, and repeat the cycle to make the transducer work at the resonant frequency, and no tuning inductor is required. The ultrasonic system phase-locking method of the present invention is suitable for various ultrasonic equipment. Compared with the method in which traditional ultrasonic equipment needs to be equipped with a tuning inductor matching the required frequency of the system, this scheme does not need to limit the ultrasonic frequency and has good versatility. In the application embodiment of medical ultrasonic knife surgery, medical workers do not need to match different transducers according to the knife head, which can reduce workload and time. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 It is a structural schematic diagram of the ultrasonic knife system;

[0040] Figure 2 is the equivalent circuit diagram of ultrasonic knife;

[0041] Figure 3 It is a schematic flow chart of a phase locking method of an ultrasonic knife system according to one embodiment of the present invention;

[0042] Figure 4 is an equivalent circuit diagram of the ultrasonic knife of the present invention;

[0043] Figure 5 Schematic diagram of voltage and current phase difference detection;

[0044] Figure 6 It is a waveform diagram of the current signal output by the generator;

[0045] Figure 7 is a vector diagram with current as the variable;

[0046] Figure 8 This is a graph showing the relationship between phase and frequency. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] See also Figure 3 As shown, an embodiment of the present invention provides a phase locking method for an ultrasonic knife system, wherein the ultrasonic knife system includes an ultrasonic knife, a transducer and a generator connected to each other, and the method includes the following steps:

[0049] Step S1, the generator generates an initial current signal and sends it to the transducer as the current working signal of the ultrasonic knife;

[0050] Step S2, measuring the voltage value and current value of the main circuit in the ultrasonic knife equivalent circuit, wherein the ultrasonic knife equivalent circuit includes a main circuit and a first branch circuit and a second branch circuit connected in parallel with the main circuit (such as Figure 4 As shown), the main circuit is that the generator is directly connected to the ultrasonic knife, and does not have a tuning inductor. The ultrasonic knife includes a connected ultrasonic knife handle and an ultrasonic knife body. The first branch is the parasitic static capacitance of the ultrasonic knife handle. The second branch includes a first inductor, a first resistor and a first capacitor connected in series, which are the electromechanical properties of the ultrasonic knife body.

[0051] Step S3, calculating the voltage effective value, current effective value, and voltage-current phase difference of the trunk circuit according to the voltage value and current value of the trunk circuit;

[0052] Step S4, calculating the voltage value, current value, and voltage-current phase difference of the second branch according to the voltage effective value, current effective value, voltage-current phase difference, and vector diagram of the main circuit;

[0053] Step S5, according to the voltage value, current value and voltage-current phase difference of the second branch, control the generator to generate a current signal at a new frequency as the current working signal of the ultrasonic knife, send it to the transducer to drive the ultrasonic knife to work, and return to step S2 to loop.

[0054] Wherein, in the step S1, the initial current signal is an initial current sinusoidal signal of a specific frequency, amplitude and arbitrary phase. In the preferred embodiment, a sinusoidal signal and a cosine signal with a phase difference of π / 2 are used. In other implementation schemes, it can also be set to other specific signals according to actual needs. The amplitude and phase of the initial current signal can also be set arbitrarily, and the frequency of the initial current signal is far away from the resonance point. Since the process and design of each ultrasonic knife are different, their resonant frequencies are different, and the resonant frequency will also decrease when the temperature rises. Because it will pass through the anti-resonance point when it is greater than the resonant frequency, the impedance near the anti-resonance point is very large, which will lead to excessive output power, oscillation and other problems. Therefore, the frequency of the initial current signal of the equipment must be less than the resonant frequency. According to experience, a frequency less than 2000-2500 of the resonant frequency is generally selected as the frequency of the initial current signal.

[0055] In step S2, the voltage and current values ​​of the main circuit in the ultrasonic knife equivalent circuit are measured and obtained by ADC sampling according to the sampling frequency. The sampling frequency is dynamically adjusted according to the frequency of the current working signal of the ultrasonic knife, for example, the base frequency is always equal to the previous output frequency, so that the voltage, current, and voltage-current phase difference of the required frequency component can be accurately obtained.

[0056] In the step S3, the voltage effective value, current effective value, and voltage-current phase difference of the trunk are calculated according to the voltage value and current value of the trunk, and the voltage effective value and current effective value of the trunk are calculated by fast Fourier transform. After the voltage effective value and current effective value of the trunk are calculated, the voltage effective value and current effective value of the trunk are detected by detecting the zero-crossing moment to obtain the voltage-current phase difference (such as Figure 5 As shown in Figure 2 ). Since the waveform of the current signal output by the generator is affected by various distortion sources in the output drive circuit (e.g., power transformer, power amplifier), high-order harmonics will be generated. The actual waveform is not a single wave (e.g., Figure 6 As shown). However, the subsequent frequency control calculation does not want to use these high-order harmonic components, so this method uses fast Fourier transform (FFT) to obtain the effective values ​​of voltage and current and then calculate the voltage and current phase difference parameter value.

[0057] In the step S4, the voltage value, current value, and voltage-current phase difference of the second branch are calculated according to the voltage effective value, current effective value, voltage-current phase difference, and vector diagram of the main circuit, including:

[0058] U 1 =U;

[0059]

[0060]

[0061] Among them, U 1 is the voltage value of the second branch, U is the effective value of the voltage of the main line, I 1 is the current value of the second branch, I is the effective value of the current of the main circuit, θ 1 is the voltage-current phase difference of the second branch, θ is the voltage-current phase difference of the main line, C 0 is the parasitic static capacitance of the ultrasonic knife handle in the first branch. Figure 7 As shown, based on the equivalent circuit, a vector diagram with current as the variable can be obtained.

[0062] In step S5, the generator is controlled to generate a current signal at a new frequency as the current working signal of the ultrasonic knife according to the voltage value, current value and voltage-current phase difference of the second branch, and the frequency change is calculated according to the first resistance, first capacitance and first inductance of the second branch and the difference between the voltage-current phase difference of the second branch and the target phase difference, including:

[0063]

[0064]

[0065]

[0066] θ′(ω) is positive; or

[0067]

[0068] θ′(ω) is negative;

[0069] Among them, f Δ is the frequency change, θ1 is the voltage and current phase difference of the second branch, ω is the angular frequency, ω=2πf, f is the frequency of the current working signal, k is the proportional coefficient, which is set according to the actual situation, θ′(ω) is the derivative of the voltage and current phase difference of the second branch with respect to the angular frequency ω, m is an intermediate variable, which is mainly used to simplify the formula and has no practical meaning, ω s is the preset fixed frequency, θ′(ω s ) is the second branch voltage and current phase difference to the preset fixed frequency ω s The derivative of is the same as the formula of θ′(ω);

[0070] Then, a current signal at a new frequency is generated according to the frequency change amount and the frequency of the current working signal as the current working signal of the ultrasonic knife.

[0071] The specific principle is that after calculating the voltage, current, and voltage-current phase difference of the second branch, the frequency of the output signal can be adjusted so that the voltage-current phase difference of the second branch approaches a certain value, such as 0 degrees. The method adopted in this embodiment is to calculate the frequency change according to the current impedance and phase difference, that is, to calculate the frequency change according to the difference between the current second branch phase difference and the target phase difference (generally 0 degrees). Figure 4 From the equivalent circuit shown, the relationship between the phase difference θ and the frequency ω is as follows:

[0072]

[0073] Taking the derivative of θ with respect to ω, we can get θ′(ω);

[0074] Then according to Figure 8 As shown, the larger the slope is when it is close to the resonance point, the smaller the frequency change is. When it is far away from the resonance point on the left side of the resonance point, the slope is very small, and a larger frequency change is required to approach the resonance point. When it is far away from the resonance point on the right side of the resonance point, the slope is negative, and it is necessary to return to the resonance point as soon as possible. The slope of the same phase difference point is different under different impedances. The smaller the impedance, the steeper the phase difference-frequency curve. Therefore, according to the above conditions, the frequency change f is obtained. Δ The calculation formula is: Adjust, if it is negative, follow the formula Return to the resonance point with a positive slope as soon as possible.s The frequency of the initial current signal can be selected and adjusted according to actual conditions.

[0075] Of course, in step S5, the generator is controlled to generate a current signal at a new frequency as the current working signal of the ultrasonic knife according to the voltage value, current value, and voltage-current phase difference of the second branch. Alternatively, the second branch series resonant frequency can be directly calculated according to the voltage value, current value, and voltage-current phase difference of the second branch as the current working signal of the ultrasonic knife, and then the frequency of the current signal of the generator is controlled to directly reach the resonant frequency. However, this method will cause the RLC circuit to oscillate if the frequency changes too much, and the impedance, capacitance, and inductance of the second branch will change according to the temperature of the knife tip and the shearing pressure of the knife head, and the calculation of the resonant frequency will have a large error.

[0076] Finally, the method further comprises:

[0077] Step S6, after the shearing is completed, the current output is turned off.

[0078] After the ultrasonic knife completes the surgical cutting work, the power supply can be turned off, the current output can be turned off, and the work can be ended.

[0079] The present invention also provides an ultrasonic knife system, which includes a connected ultrasonic knife, a transducer and a generator. The generator uses the ultrasonic knife system phase-locking method as described above to generate a current signal and send it to the transducer as the current working signal of the ultrasonic knife.

[0080] The ultrasonic knife system phase-locking method and ultrasonic knife system described in the present invention first measure the voltage value and current value of the main circuit in the ultrasonic knife equivalent circuit, then calculate the voltage value, current value, and voltage-current phase difference of the branch circuit according to the voltage value and current value of the main circuit, and then generate a new frequency signal according to the voltage value, current value, and voltage-current phase difference of the branch circuit to work, and repeat the cycle, so that the transducer works at the resonant frequency, and does not need to tune the inductor, and has good versatility.

[0081] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A phase locking method for an ultrasonic scalpel system, wherein the ultrasonic scalpel system comprises an ultrasonic scalpel, a transducer and a generator connected to each other, characterized in that: The method comprises the following steps: Step S1, the generator generates an initial current signal and sends it to the transducer as the current working signal of the ultrasonic knife; In step S1, the initial current signal is an initial current sinusoidal signal with a specific frequency and amplitude and an arbitrary phase, and the frequency of the signal is less than the resonant frequency; Step S2, measuring and obtaining the voltage value and current value of the main circuit in the ultrasonic scalpel equivalent circuit, wherein the ultrasonic scalpel equivalent circuit comprises a main circuit and a first branch circuit and a second branch circuit connected in parallel with the main circuit, wherein the main circuit is the generator directly connected to the ultrasonic scalpel and does not have a tuning inductor, and the ultrasonic scalpel comprises a connected ultrasonic scalpel handle and an ultrasonic scalpel body, wherein the first branch circuit is the parasitic static capacitance of the ultrasonic scalpel handle, and the second branch circuit comprises a first inductor, a first resistor and a first capacitor connected in series, which are the electromechanical properties of the ultrasonic scalpel body; Step S3, calculating the voltage effective value, current effective value, and voltage-current phase difference of the trunk circuit according to the voltage value and current value of the trunk circuit; Step S4, calculating the voltage value, current value, and voltage-current phase difference of the second branch according to the voltage effective value, current effective value, voltage-current phase difference, and vector diagram of the main circuit; Step S5, according to the voltage value, current value, voltage-current phase difference of the second branch, the generator is controlled to generate a current signal at a new frequency as the current working signal of the ultrasonic knife, and sent to the transducer to drive the ultrasonic knife to work, and return to step S2 for a loop; in the step S4, the voltage value, current value, voltage-current phase difference and vector diagram of the voltage effective value, current effective value, voltage-current phase difference of the second branch are calculated, include: U1=U; Among them, U1 is the voltage value of the second branch, U is the effective value of the voltage of the main circuit, I1 is the current value of the second branch, I is the effective value of the current of the main circuit, θ1 is the voltage-current phase difference of the second branch, θ is the voltage-current phase difference of the main circuit, and C0 is the parasitic static capacitance of the ultrasonic knife handle in the first branch; In step S5, the generator is controlled to generate a current signal at a new frequency as the current working signal of the ultrasonic knife according to the voltage value, current value and voltage-current phase difference of the second branch, and the frequency change is calculated according to the first resistance, first capacitance and first inductance of the second branch and the difference between the voltage-current phase difference of the second branch and the target phase difference, including: θ′(ω) is positive; or θ′(ω) is negative; Among them, f Δ is the frequency change, θ1 is the voltage and current phase difference of the second branch, ω is the angular frequency, ω=2πf, f is the frequency of the current working signal, k is the proportional coefficient, which is set according to the actual situation, θ′(ω) is the derivative of the voltage and current phase difference of the second branch with respect to the angular frequency ω, m is an intermediate variable, which is used to simplify the formula and has no actual meaning, ω s is the preset fixed frequency, θ′(ω s ) is the second branch voltage and current phase difference to the preset fixed frequency ω s The derivative of is the same as the formula of θ′(ω); Then, a current signal at a new frequency is generated according to the frequency change amount and the frequency of the current working signal as the current working signal of the ultrasonic knife.

2. The method according to claim 1, characterized in that In step S2, the voltage value and current value of the main circuit in the ultrasonic knife equivalent circuit are measured and obtained by ADC sampling according to the sampling frequency.

3. The method according to claim 2, characterized in that The sampling frequency is dynamically adjusted according to the frequency of the current working signal of the ultrasonic knife.

4. The method according to claim 1, characterized in that: In the step S3, the voltage effective value, current effective value and voltage-current phase difference of the trunk line are calculated according to the voltage value and current value of the trunk line. The voltage effective value and current effective value of the trunk line are calculated by fast Fourier transform. After the voltage effective value and current effective value of the trunk line are calculated, the voltage-current phase difference is obtained by detecting the zero-crossing moment according to the voltage effective value and current effective value of the trunk line.

5. The method according to claim 1, characterized in that In step S5, the generator is controlled to generate a current signal at a new frequency as the current working signal of the ultrasonic scalpel according to the voltage value, current value and voltage-current phase difference of the second branch. The series resonant frequency of the second branch is directly calculated according to the voltage value, current value and voltage-current phase difference of the second branch as the current working signal of the ultrasonic scalpel, and then the frequency of the current signal of the generator is controlled to directly reach the resonant frequency.

6. An ultrasonic knife system, characterized in that: The ultrasonic knife system includes a connected ultrasonic knife, a transducer and a generator. The generator uses the ultrasonic knife system phase-locking method as described in any one of claims 1 to 5 to generate a current signal and send it to the transducer as the current working signal of the ultrasonic knife.

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