Electrosurgical device, system, and method for controlling an electrosurgical device
Patent Information
- Application Number
- EP2023794279
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-10-21
- Filing Date
- 2023-10-19
- Publication Date
- 2025-07-23
AI Technical Summary
Existing electrosurgical devices face challenges in generating high-frequency alternating currents for minimally invasive surgery, particularly in achieving precise tissue sealing and cutting while minimizing nerve stimulation and avoiding carbonization, with current technologies experiencing high power losses, harmonic generation, and inaccurate voltage control.
An electrosurgical device with a primary circuit and secondary circuit, utilizing a high-frequency signal generator with multiple output stages and a transformer for galvanic isolation, employing pulse duration modulation to generate a step-shaped voltage curve following a sine reference signal, and a control unit to regulate output stages for precise voltage control.
The solution enables the generation of a clean, low-power signal with minimal harmonics, allowing for quick, safe, and reliable tissue sealing and cutting at frequencies of at least 150 kHz, improving surgical precision and reducing the risk of uncontrollable bleeding.
Smart Images
Figure 1.1
Abstract
Description
[0001] Electrosurgical device, system and method for controlling an electrosurgical device
[0002] The invention relates to an electrosurgical device for high-frequency generation. Furthermore, the invention relates to a system comprising an electrosurgical device and an electrosurgical instrument. Furthermore, the invention relates to a method for controlling an electrosurgical device.
[0003] In high-frequency surgery (HF surgery) or electrosurgery, high-frequency alternating current is passed through the human body in order to specifically damage or cut tissue through the resulting heat.
[0004] Minimally invasive endoscopy uses electrosurgical instruments for coagulation or cutting. This requires rapid and reliable tissue sealing. Even a small amount of blood is enough to obscure a surgeon's view and make a procedure difficult or even impossible. Tissue sealing essentially involves heating tissue using high-frequency current. As a result of the heating, the tissue is sealed. This makes it possible to immediately stop any bleeding that may occur.
[0005] The current used for heating should have a specific frequency to prevent nerve irritation. In other words, the nerves should not be stimulated. Typically, such frequencies are in the kHz range. A transformer can be used to achieve the required voltage. The transformer is typically operated using a half- or full-bridge on a primary side with a frequency of at least 150 kHz. A voltage can be applied on a secondary side that can be used, for example, to coagulate or cut tissue. The tissue to be treated must not be heated too intensely or for too long, as this could lead to carbonization or the formation of scabs, which could trigger further uncontrollable bleeding. However, precise or reliable voltage regulation is difficult.
[0006] In the case of bi-polar systems known from the state of the art, it is necessary that radio detection must also be present.
[0007] The frequency, as described above, is generated using a half-bridge or full-bridge. Due to their high power, the components used can only be operated digitally, meaning they can only be switched on or off. A transformer can ideally be operated with a sine wave. "Hard" switching of the transistors used can cause numerous harmonics, i.e., interference that can be critical in EMC testing and can also significantly complicate and inaccurate precise measurements of current-voltage phase shifts.
[0008] At lower frequencies, a delta modulation method can be used. However, this is not possible at higher frequencies because the transistors cannot switch quickly enough.
[0009] For example, a high-frequency surgical generator is known from WO 2010 / 025807 A1.
[0010] The object of the present invention is to overcome the disadvantages of the prior art. Preferably, the invention should be able to generate a clean signal that exhibits minimal power losses in the electronics, generates few or no harmonics, and can be controlled quickly, safely, precisely, and reliably.
[0011] This object is achieved by an electrosurgical device for high frequency generation with a frequency of at least 150 kHz for coagulation and / or cutting of tissue, comprising
[0012] - a primary circuit with a high-frequency signal generator, wherein the high-frequency signal generator has a plurality of output stages,
[0013] - a secondary circuit and - a transformer, wherein the primary circuit is galvanically isolated from the secondary circuit by means of the transformer, wherein each output stage comprises an electronic switch, wherein each of the electronic switches is configured to be switched depending on at least one desired parameter, wherein the high-frequency signal generator is configured to generate a stepped voltage curve from pulse-width-modulated rectangular voltages from the totality of the voltage curves generated by the electronic switches by means of pulse duration modulation, wherein the stepped voltage curve follows a sinusoidal reference signal, and
[0014] - a control unit which is configured to regulate an output voltage for controlling the output stages as a function of the pulse-width modulated square-wave voltages.
[0015] By using multiple electronic switches that can be switched on one after the other, a high frequency can be generated. This makes it possible to generate a sine wave with a frequency of at least 150 kHz, preferably at least 200 kHz, and more preferably at least 300 kHz.
[0016] Preferably, the electronic switch is selected from the group comprising an electrical switch, an electrical circuit, a transistor or a MOS-FET.
[0017] The electrosurgical device can generate a clean signal that has only minimal power losses in the electronics, produces few or no harmonics, and can be controlled quickly, safely, and reliably.
[0018] A primary circuit can be understood as one side of the device. A secondary circuit can be understood as the side facing away from the primary circuit, to which an instrument can be connected. An instrument, such as coagulation forceps, can be arranged or connected in the secondary circuit.
[0019] Galvanic isolation (also known as galvanic decoupling or potential separation) can be understood as the avoidance of electrical conduction between two circuits between which power or signals are to be exchanged. With galvanic isolation, the electrical potentials are separated from each other, and the circuits are then potential-free from each other. This separation must not be eliminated elsewhere, for example, via grounding. The electrical conduction is preferably separated by electrically non-conductive coupling elements. A target parameter can be understood as an "and" connection. Preferably, two conditions must be met to enable switching.
[0020] Switching can be understood as switching through or energizing.
[0021] The control unit can be a central control circuit, a control device, or a control unit. The control unit can also be a control unit, a control circuit, or a control device. "At least" can be understood as "at least."
[0022] Further embodiments can be found in the dependent claims.
[0023] Each output stage may comprise an integrated circuit, preferably an integrated circuit control circuit. An integrated circuit may be understood as an integrated circuit or an integrated circuit.
[0024] Each electronic switch can be preceded by an integrated circuit (IC). Preferably, the control unit is configured to control the IC switch(es). In other words, the output stages can be operated, activated, or switched using the control unit. Alternatively, it is possible to use only one integrated circuit (IC) for a set of output stages. The IC circuit(s) can be included in the control unit.
[0025] A sine reference signal, also called an input signal, can be determined or calculated using the control unit and / or a corresponding program. As an alternative to digital determination, the sine reference signal can also be determined analogically.
[0026] In a preferred embodiment, the control unit is configured to detect the stepped voltage curve. The stepped voltage curve preferably corresponds to an approximately sinusoidal voltage curve. In other words, the stepped voltage curve follows an approximately sinusoidal voltage curve. The more individual voltage curves that result in the stepped curve are generated, the more consistently a sinusoidal voltage curve can be generated. In other words, a sinusoidal voltage curve can be generated that preferably has no, small, or only a few jumps in its curve.
[0027] An approximately sinusoidal voltage waveform can be understood as a quasi-sinusoidal, almost sinusoidal, or nearly sinusoidal voltage waveform, a voltage waveform based on a sinusoidal shape, or a fundamentally sinusoidal voltage waveform. In a further preferred embodiment, the target parameter is defined such that switching occurs when a voltage from one of the electronic switch-generated voltage waveforms corresponds to the sinusoidal reference signal. This makes it possible to easily generate a variety of pulse width modulation output signals.
[0028] In a further preferred embodiment, each output stage has a bridge circuit or H-circuit connected upstream of the electronic switch. The bridge circuit can be configured as a half-bridge or full-bridge. The half-bridge can have two variable resistors, and the full-bridge can have four variable resistors.
[0029] In a further preferred embodiment, the control unit for generating the stepped voltage waveform from the sinusoidal reference signal comprises at least one processor. A processor is a programmable computing unit or an electronic circuit that controls other machines or electrical circuits according to transmitted commands. Processors can be implemented as integrated circuits in the form of microprocessors and microcontrollers in embedded systems. CPLDs (complex programmable logic devices), ASICs (application-specific integrated circuits), or FPGAs (field-programmable gate arrays) can be used as integrated circuits.
[0030] In a further preferred embodiment, the high-frequency signal generator is arranged
[0031] - to generate sawtooth-shaped voltage curves according to the number of electronic switches,
[0032] - to generate pulse width modulation output signals corresponding to the number of sawtooth-shaped voltage waveforms, wherein the target parameter is defined such that when a voltage of a sawtooth-shaped voltage waveform corresponds to the sinusoidal reference signal, switching takes place, and
[0033] - Based on the pulse-width modulation output signals, generate the stepped voltage curve from the pulse-width modulated square-wave voltages. This makes it possible to easily generate pulse-width modulated square-wave voltages.
[0034] In a further preferred embodiment, the high-frequency signal generator is configured to smooth the stepped voltage waveform using a low-pass filter to generate a sinusoidal voltage waveform. The provision of the low-pass filter makes it easy to smooth the stepped voltage waveform. The control unit can be configured to control the low-pass filter.
[0035] In a further preferred embodiment, a low-pass filter, preferably consisting of a coil and a capacitor (LC element), is connected downstream of each electronic switch. In particular, the high-frequency signal generator is configured to smooth the stepped signal curve using the low-pass filter with the LC element, further increasing the quality of the sine wave.
[0036] In a further preferred embodiment, the plurality of output stages is at least 3 to 20, preferably 3 to 10, particularly preferably 3, 4, 6, 8 or 10. The more output stages with which the sawtooth-shaped voltage waveforms can be generated are used, the more finely the pulse duration modulation output signal can be graded until finally a continuous or nearly continuous sine is generated or mapped, or until the quality of the sine is optimal or nearly optimal.
[0037] Tests have shown that sufficiently good sine waves were obtained with just three output stages. Tests have shown that the sine waves improved with 4, 6, 8, or 10 output stages. Tests have also shown that designs with more than 20 output stages did not result in any noticeable improvement in the shape of the sine waves in terms of smoothness. Basically, an optimization is performed, whereby irregularities, interfering waves, preferably interfering harmonics, or jumps in the sine wave can be reduced. This can also be referred to as a sine approximation or a quasi-sine.
[0038] In a further preferred embodiment, the galvanic isolation is configured to smooth the signal waveform output by the output stages. In other words, the transformer is configured to smooth the signal waveform output by the output stages. The transformer can smooth the signal to eliminate any irregularities, jumps, or outliers. A bandpass filter, for example, can be used for smoothing.
[0039] In a further preferred embodiment, the output stages are configured to be switched sequentially. Switching can be understood as switching through or supplying current.
[0040] In a further preferred embodiment, the output stages are connected in parallel and / or in series. In a further preferred embodiment, at least a first set of output stages comprising a plurality of first output stages and a second set of output stages comprising a plurality of second output stages are arranged in parallel to one another in the primary circuit.
[0041] This makes it possible to switch all the first output stages first and then all the second output stages. However, it is preferable to switch the first output stages and the second output stages alternately in sequence.
[0042] The more output stages used to generate the sawtooth-shaped voltage waveforms, the more finely the pulse width modulation output signal can be graded until finally a continuous or nearly continuous sine wave is generated or mapped, or until the quality of the sine wave is optimal or nearly optimal.
[0043] Preferably, the first set of output stages comprises at least two first output stages, and the second set of output stages comprises at least two second output stages. As mentioned above, tests have shown that increasing the number of output stages between 4 and 10 improves the quality of the sine waves. Tests have also shown that using more than 20 output stages does not result in a noticeable improvement in the shape of the sine waves in terms of smoothness.
[0044] Power can be supplied as follows:
[0045] - supplying current to at least a first set of output stages with a plurality of output stages, and subsequently
[0046] - supplying current to at least one second set of output stages with a plurality of second output stages, or
[0047] - alternating current supplying one of the first and second output stages of both sets of output stages in sequence.
[0048] The object of the invention is further achieved by a system comprising an electrosurgical device as described above and an electrosurgical instrument, wherein the electrosurgical instrument is configured for cutting and / or coagulating tissue.
[0049] Preferably, the electrosurgical instrument is a coagulation forceps. The coagulation forceps can be connected to the secondary circuit. The system enables rapid and reliable tissue sealing during minimally invasive endoscopy. A high frequency can be generated in the secondary circuit. This makes it possible to generate a sine wave with a frequency of at least 150 kHz, preferably at least 200 kHz, and more preferably at least 300 kHz.
[0050] The object of the invention is further achieved by a method for controlling an electrosurgical device for high-frequency generation with a frequency of at least 150 kHz, wherein in a primary circuit of the device there is a high-frequency signal generator with a plurality of output stages, wherein each output stage comprises an electronic switch, and wherein the primary circuit is galvanically isolated from a secondary circuit by means of a transformer, comprising the following steps:
[0051] - Switching the electronic switches depending on at least one target parameter,
[0052] - by means of the high-frequency signal generator, generating a step-shaped voltage curve from pulse-width modulated square-wave voltages, which follows a sinusoidal reference signal, by means of pulse duration modulation from the totality of the voltage curves generated by the electronic switches and
[0053] - Control of an output voltage for controlling the output stages depending on the pulse-width modulated square wave voltages by means of a control unit.
[0054] Preferably, the electronic switch is selected from the group comprising an electrical switch, an electrical circuit, a transistor or a MOS-FET.
[0055] In a preferred embodiment, the method comprises the following step
[0056] - Detecting the step-shaped voltage curve by means of the control unit, whereby the step-shaped voltage curve corresponds to an approximately sinusoidal voltage curve.
[0057] In a further preferred embodiment, the method comprises the following step
[0058] - Switch when a voltage from one of the electronic switch-generated voltage waveforms corresponds to the sine reference signal.
[0059] In a further preferred embodiment, the method comprises the following steps
[0060] - generating sawtooth-shaped voltage waveforms corresponding to the number of electronic switches, - generating pulse width modulation output signals corresponding to the number of sawtooth-shaped voltage waveforms, wherein a target parameter is defined such that when the voltage of the sawtooth-shaped voltage waveforms corresponds to a sinusoidal reference signal, and
[0061] - based on the pulse duration modulation output signals, generating the step-shaped curve from the pulse width modulated square wave voltages.
[0062] In a further preferred embodiment, the method comprises the following step
[0063] - generating sawtooth-shaped signal waveforms, depending on the number of output stages, with preferably at least 3 to 20 sawtooth-shaped signal waveforms, preferably 3 to 10 sawtooth-shaped signal waveforms, and particularly preferably 3, 4, 6, 8 or 10 sawtooth-shaped signal waveforms.
[0064] In a further preferred embodiment, the method comprises the following step
[0065] - Smoothing the step-shaped voltage curve by means of a low-pass filter to generate a sinusoidal voltage curve, wherein preferably each electronic switch is followed by a low-pass filter, preferably consisting of a coil and a capacitor (LC element).
[0066] In a further preferred embodiment, the method comprises the following step
[0067] - Smoothing the signal curve output by the output stages by means of galvanic isolation.
[0068] In a further preferred embodiment, the method comprises the following steps
[0069] - supplying current to at least a first set of output stages with a plurality of output stages, and subsequently
[0070] - supplying current to at least one second set of output stages with a plurality of second output stages, or
[0071] - alternating current supplying one of the first and second output stages of both sets of output stages in sequence.
[0072] Energizing can be understood as switching.
[0073] The drawings, the description, and the claims contain numerous features in combination. It is understood that the features mentioned above and those to be explained below can be used not only in the respective combinations specified, but also in other combinations or alone, without departing from the scope of the present invention.
[0074] The invention will be explained in more detail below using exemplary embodiments. They show:
[0075] Fig. 1 is a schematic representation of an electrosurgical device,
[0076] Fig. 2 is a schematic representation of a primary circuit from Fig. 1,
[0077] Fig. 3 a pulse width modulation diagram,
[0078] Fig. 4 is another pulse width modulation diagram based on Fig. 2,
[0079] Fig. 5 is a schematic representation of an alternative primary circuit from Fig. 1 ,
[0080] Fig. 6 is a schematic representation of another alternative primary circuit from Fig. 1,
[0081] Fig. 7 is a schematic representation of yet another alternative primary circuit from Fig. 1,
[0082] Fig. 8 is a circuit diagram based on the arrangement of the output stages according to Fig. 7, and
[0083] Fig. 9 is a voltage diagram based on Fig. 8.
[0084] Fig. 1 shows an electrosurgical device 1. The electrosurgical device 1 is used to generate high frequencies for coagulation and / or cutting tissue. The frequency achievable with the electrosurgical device 1 is at least 150 Hz, preferably at least 200 kHz, or more preferably at least 300 kHz. The electrosurgical device 1 comprises a primary circuit 2 with a high-frequency signal generator 3, a secondary circuit 15, and a transformer 12. The primary circuit 2 is galvanically isolated from the secondary circuit 15 by means of the transformer 12. The secondary circuit 15 has a first ohmic resistor 20 and a second capacitive resistor 21. The resistors 20, 21 can be understood as tissue resistance. An instrument, e.g., coagulation forceps, can be arranged or connected in the secondary circuit 15 (not shown).
[0085] Fig. 2 shows a schematic representation of the primary circuit 2 in detail from Fig. 1.
[0086] The high-frequency signal generator 3, which is arranged in the primary circuit 2, comprises three output stages 5. Each of the three output stages 5 comprises an electronic switch 7, which is preferably designed as a MOS-FET, and an integrated circuit 6. The integrated circuits 6 are connected upstream of the electronic switches 7. The electronic switches 7 are controlled or activated by the integrated circuits 6. The electronic switches 7 are configured to be switched depending on at least one desired parameter. A low-pass filter consisting of a coil and a capacitor (LC element 8) is connected downstream of each electronic switch 7. As further shown in Fig. 2, the high-frequency signal generator 3 comprises a control unit 4. The control unit 4 can be understood as a central control circuit. The control unit 4 is preferably configured to control or activate the integrated circuits 6.
[0087] Fig. 3 shows a pulse width modulation diagram. A voltage waveform a generated by an electronic switch 7 is designed as a sawtooth profile or is sawtooth-shaped. The sawtooth profile can be understood as a counter that counts from 0 to a predetermined value, where it is then reset to 0. The rise of the voltage waveform is linear, while the fall of the voltage waveform is abrupt. After completing a cycle from rise to fall, the cycle can then begin again.
[0088] A sinusoidal reference signal S (also input signal) can be determined or calculated in a processor of the control unit 4 and / or by means of a corresponding program. Alternatively, it is also possible to determine the sinusoidal reference signal S analogously. A logical "and" operation is then added. In this case, the sinusoidal reference signal S is linked to the sawtooth profile in order to generate a logical 1 starting at a certain counter reading. This generates a pulse duration modulation output signal in the form of a pulse-width modulated square-wave voltage A. However, a single pulse-width modulated square-wave voltage is not sufficient to generate a sinusoidal voltage waveform or an approximately sinusoidal waveform sufficiently well.
[0089] Fig. 4 shows another pulse width modulation diagram based on Fig.
[0090] 2. Instead of just one pulse-width modulated square-wave voltage according to Fig. 3, three pulse-width modulated square-wave voltages A, B, C are now generated.
[0091] The high-frequency signal generator 3 is configured to generate a stepped voltage waveform D from the pulse-width modulated rectangular voltages A, B, C by means of pulse duration modulation from the totality of the voltage waveforms a, b, c generated by the three electronic switches 7. The three electronic switches 7 are switched on one after the other. The stepped voltage waveform D follows the sinusoidal reference signal S. To generate the stepped voltage waveform D from the sinusoidal reference signal S, the control unit 4 comprises at least one processor.
[0092] In detail, the high-frequency signal generator 3 is designed to generate the three sawtooth-shaped voltage waveforms a, b, c according to the three electronic switches 7,
[0093] - to generate pulse width modulation output signals corresponding to the three sawtooth-shaped voltage waveforms a, b, c, wherein the target parameter is defined such that switching occurs when a voltage of a sawtooth-shaped voltage waveform a, b, c corresponds to the sinusoidal reference signal S, and
[0094] - to generate the step-shaped voltage curve D from the pulse width modulated square wave voltages A, B, C starting from the pulse width modulation output signals.
[0095] The control unit 4 is configured to regulate an output voltage for driving the three output stages 5 depending on the pulse-width-modulated square-wave voltages A, B, C. Furthermore, the control unit 4 is configured to detect the stepped voltage curve D, which corresponds to or follows an approximately sinusoidal voltage curve.
[0096] The above-mentioned target parameter is defined in such a way that switching occurs when a voltage from one of the voltage curves a, b, c generated by one of the electronic switches 7 corresponds to the sinusoidal reference signal S.
[0097] Each of the output stages 5 can have a half-bridge or full-bridge connected upstream of the electronic switch 7. The transformer 12 can be configured to be operated by means of the half-bridge or full-bridge in the primary circuit 2.
[0098] Furthermore, the high-frequency signal generator 3 is configured to smooth the stepped voltage waveform D using a low-pass filter (LC element 8) to generate a sinusoidal voltage waveform. In other words, the quality of the sinusoidal waveform can be increased or improved using the low-pass filter.
[0099] The galvanic isolation is designed to further smooth the signal waveform output by the 5 output stages. In other words, the transformer is designed to further smooth the signal waveform output by the 5 output stages. This makes it possible to further smooth the voltage waveform. In other words, the quality of the sine waveform can be further increased or improved using the galvanic isolation or the transformer.
[0100] The device 1 with at least the three output stages 5 is sufficient to generate a sinusoidal voltage waveform or an approximately sinusoidal waveform sufficiently well. Fig. 5 shows an alternative schematic representation of the primary circuit 2 in detail from Fig. 1. In contrast to Fig. 2, instead of the three output stages 5, a total of four output stages 5, 10 are provided. A first set of output stages with two first output stages 5 and a second set of output stages with two second output stages 10 are arranged in parallel in the primary circuit 2. The four electronic switches 7, which are preferably designed as MOS-FETs, are switched on one after the other.
[0101] Fig. 6 shows a further alternative schematic representation of the primary circuit 2 in detail from Fig. 1. In contrast to Fig. 2, a total of six output stages 5, 10 are provided instead of the three output stages 5. A first set of output stages with three first output stages 5 and a second set of output stages with three second output stages 10 are arranged in parallel in the primary circuit 2. The six electronic switches 7, which are preferably designed as MOSFETs, are switched on one after the other.
[0102] The following explanations for Fig. 7 also apply correspondingly to Fig. 5 and Fig. 6, which have fewer output stages than shown in Fig. 7.
[0103] Fig. 7 shows a further alternative schematic representation of the primary circuit 2 in detail from Fig. 1. In contrast to Fig. 2, a total of ten output stages 5, 10 are provided instead of the three output stages 5. A first set of output stages with five first output stages 5 and a second set of output stages with five second output stages 10 are arranged in parallel in the primary circuit 2.
[0104] Fig. 8 is a switching diagram over time based on the arrangement of the output stages 5, 10 according to Fig. 7. The first set of output stages with the five first output stages 5 is divided in the diagram into the five first output stages A1 to A5. The second set of output stages with the five second output stages 10 is divided in the diagram into the five second output stages B1 to B5. Switching or energization takes place in sequence according to the number sequence 1 to 10, as follows: A1, B1, A2, B2, A3, B3, A4, B4, A5 and B5. Once this cycle has been completed, it starts again from the beginning.
[0105] The high-frequency signal generator 3 of Fig. 7 is configured, similarly to the high-frequency signal generator 3 shown in Fig. 2, to generate a stepped voltage waveform (not shown) from the pulse-width modulated square-wave voltages A1, B1, to A5, B5 by means of pulse duration modulation from the totality of the voltage waveforms generated by the ten electronic switches 7 (not shown). The stepped voltage waveform follows a sinusoidal reference signal S (not shown). The control unit 4 is configured to detect the stepped voltage waveform D, which corresponds to or follows an approximately sinusoidal voltage waveform.
[0106] To generate the step-shaped voltage curve D from the sinusoidal reference signal S, the control unit 4 comprises at least one processor, wherein the control unit 4, as described above, is set up to regulate an output voltage for controlling the output stages 5 as a function of the pulse-width modulated square-wave voltages A1, B1, to A5, B5.
[0107] The high-frequency signal generator 3 is configured to smooth the step-shaped voltage curve by means of a low-pass filter in order to generate a sinusoidal voltage curve.
[0108] The voltage diagram over time shown in Fig. 9 is based on the switching diagram over time according to Fig. 8. The one sinusoidal curve SS (secondary voltage: 200V / div) is much smoother than the other sinusoidal curve PS (primary voltage: 5V / div), ie more continuous with few or preferably small jumps in the course.
[0109] The invention makes it possible to generate a clean sine signal that has only low power losses in the electronics, generates no or only a few harmonics, and can be controlled quickly, safely, precisely, and reliably.
[0110] The invention relates to an electrosurgical device 1 for high-frequency generation, comprising a high-frequency signal generator 3 having a plurality of output stages 5, each output stage 5 comprising an electronic switch 7, each of the electronic switches 7 being configured to be switched as a function of at least one desired parameter, the high-frequency signal generator 3 being configured to generate, by means of pulse duration modulation, from the totality of the voltage waveforms generated by the electronic switches 7, a stepped voltage waveform comprising pulse-width-modulated square-wave voltages, which follows a sinusoidal reference signal, and a control unit 4 being configured to regulate an output voltage for driving the output stages 5 as a function of the pulse-width-modulated square-wave voltages. The drawings, the description, and the claims contain numerous features in combination.It is understood that the above-mentioned features can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.
[0111] 1 Device 2 Primary circuit
[0112] 3 High-frequency signal generator 4 Control unit
[0113] 5 Output stage 6 IC (control circuit)
[0114] 7 electronic switch 8 LC element 10 output stage 12 transformer 15 secondary circuit 20 resistor 21 resistor a voltage curve b voltage curve c voltage curve A square wave voltage
[0115] A1 Square wave voltage A2 Square wave voltage A3 Square wave voltage A4 Square wave voltage A5 Square wave voltage B Square wave voltage
[0116] B1 Square wave voltage B2 Square wave voltage B3 Square wave voltage B4 Square wave voltage B5 Square wave voltage C Square wave voltage D Step-shaped voltage curve PS Primary signal S Sinusoidal reference signal SS Secondary signal
Claims
Claims 1. Electrosurgical device (1) for high frequency generation with a frequency of at least 150 kHz for coagulation and / or cutting of tissue, comprising - a primary circuit (2) with a high-frequency signal generator (3), wherein the high-frequency signal generator (3) has a plurality of output stages (5), - a secondary circuit (15) and - a transformer (12), wherein the primary circuit (2) is galvanically isolated from the secondary circuit (15) by means of the transformer (12), wherein each output stage (5) comprises an electronic switch (7), wherein each of the electronic switches (7) is configured to be switched as a function of at least one desired parameter, wherein the high-frequency signal generator (3) is configured to generate, by means of pulse duration modulation, from the totality of the voltage waveforms generated by the electronic switches (7), a stepped voltage waveform comprising pulse-width-modulated rectangular voltages, which follows a sinusoidal reference signal, and - a control unit (4) which is designed to regulate an output voltage for controlling the output stages (5) as a function of the pulse-width modulated square-wave voltages.
2. Electrosurgical device (1) according to claim 1, wherein the control unit (4) is configured to detect the step-shaped voltage curve, which corresponds to an approximately sinusoidal voltage curve.
3. Electrosurgical device (1) according to claim 1 or 2, wherein the target parameter is defined such that when a voltage generated by one of the electronic switches (7) corresponds to the sinusoidal reference signal, switching takes place, wherein the electronic switch (7) is preferably a MOS-FET.
4. Electrosurgical device (1) according to one of the preceding claims, wherein each output stage (5) has a bridge circuit, preferably a half or full bridge, connected upstream of the electronic switch (7).
5. Electrosurgical device (1) according to one of the preceding claims, wherein the control unit (4) comprises at least one processor for generating the step-shaped voltage curve from the sinusoidal reference signal. Electrosurgical device (1) according to one of the preceding claims, wherein the high-frequency signal generator (3) is arranged - to generate sawtooth-shaped voltage curves according to the number of electronic switches (7), - to generate pulse width modulation output signals corresponding to the number of sawtooth-shaped voltage waveforms, wherein the target parameter is defined such that when a voltage of a sawtooth-shaped voltage waveform corresponds to the sinusoidal reference signal, switching takes place, and - generating the stepped voltage waveform from the pulse-width modulated square-wave voltages based on the pulse-duration modulation output signals. Electrosurgical device (1) according to one of the preceding claims, wherein the high-frequency signal generator (3) is configured to smooth the stepped voltage waveform using a low-pass filter in order to generate a sinusoidal voltage waveform. Electrosurgical device (1) according to one of the preceding claims, wherein a low-pass filter, preferably comprising a coil and a capacitor (LC element 8), is connected downstream of each electronic switch (7). Electrosurgical device (1) according to one of the preceding claims, wherein the plurality of output stages (5) is at least 3 to 20, preferably 3 to 10.Electrosurgical device (1) according to one of the preceding claims, wherein the galvanic isolation is configured to smooth the signal curve output by the output stages (5). Electrosurgical device (1) according to one of the preceding claims, wherein the output stages (5) are configured to be connected in series. Electrosurgical device (1) according to one of the preceding claims, wherein the output stages (5) are connected in parallel and / or in series. Electrosurgical device (1) according to one of the preceding claims, wherein at least a first set of output stages with a plurality of first output stages (5) and a second set of output stages with a plurality of second output stages (10) are arranged in parallel to one another in the primary circuit (2). A system comprising an electrosurgical device (1) according to one of the preceding claims and an electrosurgical instrument, wherein the electrosurgical instrument is configured for cutting and / or coagulating tissue. A method for controlling an electrosurgical device (1) for high-frequency generation with a frequency of at least 150 kHz, wherein a primary circuit (2) of the device (1) includes a high-frequency signal generator (3) with a plurality of output stages (5), each output stage (5) comprising an electronic switch (7), and wherein the primary circuit (2) is galvanically isolated from a secondary circuit (15) by means of a transformer (12), comprising the following steps: - switching the electronic switches (7) depending on at least one target parameter, - by means of the high-frequency signal generator (3) generating a step-shaped voltage curve from pulse-width modulated square-wave voltages, which follows a sinusoidal reference signal, by means of pulse duration modulation from the totality of the voltage curves generated by the electronic switches (7) and - Regulating an output voltage for controlling the output stages (5) as a function of the pulse-width modulated square-wave voltages by means of a control unit (4). Method according to claim 15, further comprising the following step - Detecting the step-shaped voltage curve by means of the control unit, wherein the step-shaped voltage curve corresponds to an approximately sinusoidal voltage curve. Method according to claim 15 or 16, further comprising the following step - Switching when a voltage generated by one of the electronic switches (7) corresponds to the sinusoidal reference signal, wherein the electronic switch (7) is preferably a MOS-FET. Method according to one of claims 15 to 17, further comprising the following steps - Generation of sawtooth-shaped voltage waveforms corresponding to the number of electronic switches (7), - generating pulse width modulation output signals corresponding to the number of sawtooth-shaped voltage waveforms, wherein a target parameter is defined such that when the voltage of the sawtooth-shaped voltage waveforms corresponds to a sinusoidal reference signal, and - based on the pulse duration modulation output signals, generating the step-shaped curve from the pulse-width modulated square-wave voltages. Method according to one of claims 15 to 18, further comprising the following step - generating sawtooth-shaped signal waveforms, depending on the number of output stages (5), with preferably at least 3 to 20 sawtooth-shaped signal waveforms, preferably 3 to 10 sawtooth-shaped signal waveforms.
20. The method according to any one of claims 15 to 19, further comprising the following step - Smoothing the stepped voltage curve by means of a low-pass filter to generate a sinusoidal voltage curve, wherein preferably each electronic switch (7) is followed by a low-pass filter, preferably consisting of a coil and a capacitor (LC element 8). Method according to one of claims 15 to 20, further comprising the following step - Smoothing the signal waveform output by the output stages (5) by means of galvanic isolation. Method according to one of claims 15 to 21, further comprising the following steps - supplying current to at least one first set of output stages with a plurality of output stages (5), and subsequently - supplying current to at least one second set of output stages with a plurality of second output stages (10), or - alternately energizing one of the first and second output stages (5, 10) of both sets of output stages in sequence.