Generator with regenerative device

Abstract

A generator with a regeneration device. The electrosurgical generator according to the invention includes an oscillating circuit excited by means of an excitation circuit having a frequency preferably close to its resonant frequency, wherein the oscillation should be periodically interrupted. This can be done, for example, in situations where a pulse-pause modulation of a radio frequency voltage must be created, the fundamental frequency of which, for example, 350 kHz or 500 kHz, can be modulated with a modulation frequency of, for example, 50 kHz. To stop the oscillation in the generator's oscillating circuit as abruptly as possible without losing the energy stored in the oscillating circuit, a regeneration circuit is provided, implemented by means of a voltage multiplier circuit. Compared to a boost converter coupled inductor, it has the advantage of providing a low capacitive load to the oscillating circuit, especially because it is only electrically effectively connected to the oscillating circuit via a switch during the regeneration phase. This concept allows for efficient energy regeneration and therefore allows for precise amplitude modulation of the radio frequency voltage, particularly square wave modulation (on-off-switch).

Description

Technical Field

[0001] This invention relates to an electrosurgical generator with a regenerative device. Background Technology

[0002] Electrosurgical generators typically provide radiofrequency voltage for the operation of electrical instruments. Such generators usually include an oscillating circuit that supplies both radiofrequency voltage and current to the electrosurgical instruments. In many cases, the radiofrequency voltage must be modulated to achieve a specific surgical purpose.

[0003] A generator is known from DE 100 46 592 A1, in which the amplitude of the radio frequency voltage is modulated by means of a square wave. At the end of the oscillation cycle of the oscillator circuit, the oscillation must be stopped as quickly as possible. DE 100 46 592 A1 proposes a suppression circuit for this purpose. It includes an inductor that is transformer-coupled to the oscillation circuit inductor of the generator, and the energy removed from the oscillation circuit is supplied to a suppression resistor that converts the energy into heat. In doing so, the oscillation decay of the generator oscillation circuit is accelerated, and the oscillation stops rapidly.

[0004] This method can indeed achieve good modulation of surgical voltage, but it comes with high energy consumption.

[0005] As a remedy, EP 2 424 458 B1 proposes a regenerative circuit instead of a resistor to eliminate energy contained in the oscillating circuit. This regenerative circuit feeds the energy back to the storage capacitor at the end of the RF pulse and converts only the remaining energy into heat in the ohmic resistor, which cannot be fed back to the storage capacitor. In doing so, the process of stopping the oscillation of the oscillating circuit is carried out in two stages. In the first stage, the energy of the oscillating circuit is regenerated in the storage capacitor, and in the second stage, the remaining energy still contained in the oscillating circuit is converted into heat. Higher energy efficiency can be achieved using this concept. However, the energy component must still be eliminated. Furthermore, there is a desire for more efficient and faster suppression of the oscillating circuit.

[0006] Other existing technologies include DE 40 09 819 A1, US 44 29 694, JP H 08–2 99 356, WO 98 / 07378 A1, WO 03 / 090635, US 4 281 373 A, WO 98 / 27880, DE 10 046 592 A1 and US 6 261286 B1. Summary of the Invention

[0007] Therefore, the object of the present invention is to provide a generator with an improved regeneration circuit.

[0008] This objective is achieved by means of the generator according to claim 1:

[0009] The generator according to the invention includes a regenerative circuit that can be activated and deactivated in a controlled manner. For example, corresponding switching elements are used for controlled activation and deactivation. When activated, the regenerative circuit connects the oscillating circuit of the electrosurgical generator to a buffer capacitor to feed energy from the oscillating circuit back to the supply circuit, and particularly to the buffer capacitor provided there. According to the invention, the regenerative circuit includes a voltage multiplier circuit, particularly a voltage multiplier circuit implemented by a capacitor-diode combination. When activated, the voltage multiplier circuit removes electrical energy from the oscillating circuit, thereby constructing a voltage that increases with each oscillation, a multiple of the voltage removed from the oscillating circuit. The amount of voltage multiplication is obtained from the number of stages in the voltage multiplier circuit. By means of voltage multiplication, the energy present in the oscillating circuit is regenerated to the buffer capacitor very quickly and efficiently, thereby maintaining the suppression of the oscillating circuit if the voltage in the oscillating circuit is less than the supply voltage. Furthermore, the voltage of the buffer capacitor can be increased during regeneration without hindering the regeneration process.

[0010] The concept according to the invention specifically eliminates the need for suppression resistors to suppress voltage residuals in the oscillating circuit. In doing so, the generator according to the invention allows the RF voltage of the oscillating circuit to operate in the range from 100 kHz to several MHz, with high modulation frequencies in the range of tens of kHz, for example, 20 kHz, 40 kHz, 60 kHz, 80 kHz or even higher. Furthermore, the energy efficiency of the mode is particularly improved, where the on-time of the RF pulse is correspondingly very short, such as, for example, in the cut mode, where the pulse-pause ratio of the modulated RF voltage is particularly low.

[0011] Typically, the oscillating circuit is a parallel oscillating circuit, consisting of at least one oscillating circuit inductor and at least one oscillating circuit capacitor. An excitation circuit is assigned to the oscillating circuit, configured to excite the oscillating circuit at its resonant frequency. In its simplest case, the excitation circuit includes a controlled switch that supplies energy to the parallel oscillating circuit in pulses. However, the excitation circuit may also include, for example, multiple controlled switches in a half-bridge circuit or a bridge circuit.

[0012] The supply circuit is preferably a DC voltage source, which includes a storage capacitor disposed at its output. The DC voltage source can be a voltage converter circuit, such as a PFC (Power Factor Correction) circuit. A flyback converter can be used for this purpose. The PFC circuit supplies a substantially constant DC voltage from the pulsating rectified AC mains voltage. Other converter circuits may also be used.

[0013] The storage capacitor placed at the output of the supply circuit forms a buffer that absorbs the energy supplied by the regeneration circuit. It can then be used again to supply the oscillation circuit.

[0014] The regenerative circuit can be directly connected to the oscillator circuit inductor. Alternatively, the regenerative circuit can be connected to a regenerative inductor that is transformer-coupled to the oscillator circuit inductor. In both cases, the voltage multiplier circuit increases the voltage derived from the oscillator circuit, thus achieving efficient energy regeneration.

[0015] Preferably, the voltage multiplier circuit is a so-called capacitor cascade, particularly a multi-stage cascade. Such a circuit comprises two series circuits of multiple capacitors, whereby the connection point of each series circuit's capacitor is connected to the connection point of the corresponding capacitor series circuit via a zigzag-arranged diode chain. To activate or deactivate the voltage multiplier circuit, a switch is preferably provided. It is preferably arranged between the regenerative inductor or oscillating circuit capacitor and the voltage multiplier circuit. This concept minimizes capacitive coupling between the regenerative circuit and the oscillating circuit when the regenerative circuit is inactive, and thus allows the generator to operate undisturbed outside the regeneration phase. The switch is preferably configured and controlled such that the regenerative circuit is connected to the oscillating circuit only during the regeneration phase.

[0016] The generator according to the invention preferably includes a control circuit configured to alternately activate the excitation circuit on one hand and the regeneration circuit on the other. This allows the oscillation of the oscillation circuit to be switched on and off, making near-perfect square wave modulation of the generator's RF output voltage possible. Other types of modulation, such as sawtooth modulation, are also possible. The invention always offers an advantage if the desired modulation requires a steep trailing edge, i.e., a rapid cessation of the RF oscillation. Attached Figure Description

[0017] Further details of the advantageous embodiments are subject to the dependent claims, the description, and the associated drawings. The drawings illustrate:

[0018] Figure 1 The generator with connecting device according to the invention is illustrated in a schematic overview.

[0019] Figure 2according to Figure 1 A simplified circuit diagram of the generator.

[0020] Figure 3 according to Figure 1 The circuit diagram of the modified generator,

[0021] Figure 4 according to Figure 1 Another schematic circuit diagram of the generator, and

[0022] Figure 5 Used for illustration Figure 1-4 A diagram showing the oscillating behavior of the generator. Detailed Implementation

[0023] Figure 1 The diagram illustrates a generator 10 for providing a surgical voltage at output 11. This applies to bipolar surgical instruments or similar devices. Figure 1 The monopolar surgical instrument shown in the diagram and the neutral electrode 13 can be connected thereto. The instrument 12 and the neutral electrode 13 can be connected to the output 11 via corresponding lines 14 and 15.

[0024] The device 12 includes at least one electrode 16, which will affect the patient's biological tissues. Conversely, a neutral electrode 13 is widely configured to allow current to flow between the patient and the neutral electrode 13 without physiological effect.

[0025] exist Figure 1 The image schematically illustrates device 12. It can be a cutting instrument, a coagulation instrument, or any other monopolar or bipolar electrosurgical instrument. In the case of a bipolar instrument, it comprises two electrodes, both of which are connected to output 11 via corresponding lines or cables.

[0026] Generator 10 is particularly suitable for supplying pulsed radio frequency (RF) voltage to devices that require such supply. Pulsed radio frequency (RF) voltage specifically refers to a voltage having a fundamental frequency between 100 kHz and 5 MHz, preferably between 300 kHz and 500 kHz, and amplitude modulated by means of a square wave pulse sequence. This means that the amplitude of the RF voltage generated by generator 10 alternates between a first and a second value in terms of its value with respect to the frequency of the square wave pulse sequence, for example, alternating between multiples of 100 volts and 0 volts, or between multiples of 100 volts and only multiples of 10 volts. Therefore, the RF voltage is, for example, " Connect / Disconnect switch "Voltage. However, the present invention is also suitable for creating RF voltages with other modulation shapes, such as RF voltages with sawtooth modulation and all other modulation shapes, especially those in which it is important that the RF oscillation stops rapidly at the end of the RF voltage pulse."

[0027] The structure of generator 10 is used Figure 1 An overview is shown in the diagram. To create the desired radio frequency AC voltage for the oscillation circuit 17, the oscillation circuit 17 includes at least one oscillation circuit capacitor 18 and at least one oscillation circuit inductor 19 connected in parallel with each other.

[0028] To supply radio frequency energy to device 12, oscillation circuit 17 is connected to decoupling circuit 20. In this embodiment, decoupling circuit 20 is implemented by means of at least one decoupling inductor 21, which is magnetically coupled (transformer-coupled) to oscillation circuit inductor 19. Other decoupling circuits are possible. Decoupling inductor 21 may consist of multiple sub-inductors connected in series with each other. Preferably, oscillation circuit inductor 19 and decoupling inductor 21 thus form a transformer with a transfer factor greater than 1. The transfer factor is the ratio of the number of windings of decoupling inductor 21 to the number of windings of oscillation circuit inductor 19.

[0029] To excite and sustain oscillations in the oscillation circuit 17, an excitation circuit 22 is provided, which supplies excitation energy to the oscillation circuit 17. The excitation circuit 22 includes a DC voltage source 23 for providing DC voltage power. A line supplying the corresponding DC voltage V is connected to a buffer capacitor 24. The latter is used to store energy and also to absorb energy regenerated from the oscillation circuit 17 in the event that the RF oscillation of the oscillation circuit 17 ceases.

[0030] A regeneration circuit 25 is provided to regenerate energy from the oscillation circuit 17 when the RF oscillation stops. It connects the oscillation circuit 17 to the buffer capacitor 24 so that energy is regenerated on the buffer capacitor 24 whenever the oscillation of the oscillation circuit 17 should stop as quickly as possible.

[0031] Figure 2 A more detailed circuit diagram of generator 10 is shown, particularly of the regeneration circuit 25. As is clear, in its simplest form, excitation circuit 22 can be implemented by an electronically controlled switch 26 and its associated control circuit 27. Switch 26 is arranged in either oscillation circuit 17 or regeneration inductor 29. Figure 3 The circuit is connected between the input of the regenerative circuit 25 and the input of the oscillating circuit 17. If it is on, the regenerative circuit 25 is active and, under its suppression, returns the energy supply from the oscillating circuit 17 to the buffer capacitor 24. If it is off, the regenerative circuit is inactive and does not suppress the oscillating circuit 17.

[0032] The regenerative circuit 25 can be directly connected to the oscillation circuit 17. Therefore, its two input lines a and b can be directly connected to the input of the regenerative circuit. Lines a and c thus form the output of the regenerative circuit 25.

[0033] The regenerative circuit 25 is preferably a voltage multiplier circuit. It comprises two branches, each connected in series with multiple capacitors, for example, two, three, four, or more capacitors. In one branch, capacitors C11, C12, and C13 are connected in series with each other. In the other branch extending parallel to it, capacitors C21, C22, and C23, provided in equal numbers, are connected in series with each other. The connection points between the corresponding capacitors of the two branches are connected to each other by means of diodes, thereby creating a common voltage multiplier circuit. Diodes D1 to D7 are arranged in a zigzag pattern between the branches formed by capacitors C11 to C13 and C21 to C23. Diodes D1 to D7 are connected in series with the same polarity, that is, at each connection point, the anode of one diode and the cathode of another diode are connected to each other.

[0034] The activation switch 28, arranged in line b, is part of the regenerative circuit 25. Line b forms the connection between the oscillation circuit 17 and the regenerative circuit 25. The activation switch is configured to open and close the current path in line b.

[0035] Activation switch 28 and electronic switch 26 are controlled in a coordinated manner. For control, a control device B29 can be provided, which directly controls switches 26 and 28, or also controls switches 26 and 28 via an inserted control circuit (such as control circuit 27). The control circuit opens and closes switch 26 synchronously with the oscillation of oscillating circuit 17, whenever oscillating circuit 17 is to be energized. If oscillation is to stop, switch 26 remains in the non-conducting state, and switch 28 transitions to the conducting state. If oscillation is to restart, switch 28 transitions to the non-conducting state, and switch 26 again turns on and off at a switching frequency according to the resonant frequency of oscillating circuit 17.

[0036] The modified embodiment of generator 10 in Figure 3 The diagram is shown in the image. Regarding the basic description, the explanations above apply, based on the reference symbols already introduced:

[0037] Although according to Figure 2 In one embodiment, lines a and b of the regeneration circuit 25 are directly connected to the oscillation circuit, but according to... Figure 3 In this embodiment, lines a and b are connected to regenerative inductor 29, which is coupled to oscillating circuit inductor 19 in a transformer-type manner. The regenerative inductor 29 and oscillating circuit inductor 19 thus form a transformer with a transfer factor preferably between 1 and 2. Other transfer factors are possible. The transfer factor is defined as the ratio between the number of windings in the regenerative inductor 29 and the number of windings in the oscillating circuit inductor 19.

[0038] Figure 4A further modification to generator 10 is illustrated. Here, the excitation circuit includes multiple switches 26a, 26b, 26c, 26d forming a bridge circuit to excite oscillation circuit 17. Figure 4 The diagram illustrates a full-bridge circuit with four switches 26a-26d. However, a half-bridge circuit can also be used to excite the oscillating circuit 17, in which two switches (e.g., switches 26a and 26b) are replaced by capacitors.

[0039] The basis described above Figure 2 The generator 10 operates as follows:

[0040] For the sake of description, it is assumed by way of example that the oscillating circuit 17 has a resonant frequency between 200 kHz and 1 MHz, such as 350 kHz, 500 kHz, etc. Therefore, a control device B29 is provided to open and close the switch 26 at this frequency in order to excite the oscillating circuit 17 at its resonant frequency. For example, a DC voltage source 23 supplied from the general power grid 30 provides a DC voltage, for example, multiples of 100 volts (e.g., 300 V), between ground and the operating voltage line V, such that the buffer capacitor 24 is loaded with the operating voltage (e.g., 300 V).

[0041] like Figure 5 As illustrated in the diagram, if we now assume that the oscillations present in oscillation circuit 17 should pulse with a square wave function R, then an oscillation pause PA must be created between individual pulses PU. RF voltage U HF The pulse PU can have a length of, for example, a few microseconds, such as 5. The duration of the pause PA between individual pulses of the RF voltage depends on the modulation frequency and the so-called duty cycle. Especially in cut-out modes, where the RF can be very high (several kilovolts) and the pulse PUs of the RF voltage are very short (each pulse PU of the RF voltage has one or more RF oscillations), the pulse-pause ratio can be small, and therefore the duration of the RF pause PA is quite long (e.g., 100). ).

[0042] In generator 10, it is important to quickly and efficiently stop the RF oscillation at the end of each RF voltage pulse PU so that the oscillation circuit 17 does not produce or only produces a small number of afterpulse oscillations. Figure 5 The attenuation curve 31 is illustrated with a dashed line because it can appear in a generator without the suppression provided by the regeneration circuit 25. However, because the control device B29 closes the switch 28 at the end of the RF voltage pulse PU, and thus activates the regeneration circuit 25, Figure 5The decay process, illustrated by solid lines, is drastically shortened. Thus, it is assumed that the regeneration circuit 25 includes capacitors C11 to C23, which are loaded due to the previous regeneration operation. The energy contained in the oscillation circuit 17 is thus transferred to the buffer capacitor 24 with several oscillations of the oscillation circuit 17. Similarly, even as the oscillation amplitude of the oscillation circuit 17 decays, the regeneration process continues because the regeneration circuit 25 operates as a voltage multiplier circuit, and therefore the voltage that decreased during the RF oscillation decay due to multiplication is increased again to a value sufficient to supply the buffer capacitor 24.

[0043] The electrosurgical generator 10 according to the invention includes an oscillating circuit excited by means of an excitation circuit having a frequency preferably close to its resonant frequency, wherein the oscillation should be periodically interrupted. This can be, for example, at the radio frequency voltage U that must be created. HF This is accomplished in a pulse-pause modulation scenario, where the fundamental frequency, for example, 350 kHz or 500 kHz, can be modulated using a modulation frequency of, for example, 50 kHz. Other modulation frequencies are possible. Typically, they are below 100 kHz. To stop the oscillation in the generator's oscillation circuit as abruptly as possible without losing the energy stored in the oscillation circuit 17, a regeneration circuit 25 is provided, which is implemented by means of a voltage multiplier circuit. Compared to a boost converter coupled inductor, it has the advantage of providing a low capacitive load to the oscillation circuit 17, especially since it is only electrically and effectively connected to the oscillation circuit 17 via switch 28 during the regeneration phase. This concept allows for efficient energy regeneration and therefore allows for RF voltage U HF Precise amplitude modulation, especially square wave modulation (on-off-switch).

[0044] Reference symbol list:

[0045] 10 Generators

[0046] 11 Output

[0047] 12 instruments

[0048] 13 Neutral electrode

[0049] Lines 14 and 15

[0050] 16 electrodes

[0051] 17 Oscillating Circuit

[0052] 18. Oscillating circuit capacitor

[0053] 19. Inductor in oscillating circuit

[0054] 20 Decoupling Circuit

[0055] 21 Decoupling Inductor

[0056] 22 Supply Circuit / Excitation Circuit

[0057] 23 DC voltage source

[0058] 24 Buffer capacitor

[0059] 25 Regenerative Circuit

[0060] 26 Electronic switches

[0061] 27 Control Circuit

[0062] Lines a, b, and c

[0063] C11–C13 Capacitors of the first branch

[0064] C21–C23 Capacitors of the second branch

[0065] Diodes D1–D7

[0066] 28. Activate switch

[0067] 29 Inductors

[0068] B29 Control Equipment

[0069] 30 Power Grid

[0070] PU RF voltage pulse

[0071] PA RF pause

[0072] 31 Attenuation Curve

[0073] U HF Radio frequency voltage.

Claims

1. An electrosurgical generator (10). The device includes an oscillation circuit (17) comprising at least one oscillation circuit inductor (19) and at least one oscillation circuit capacitor (18) and is connected to an excitation circuit (22) configured to create electrical oscillations in the oscillation circuit (17). It has a DC voltage source (23), which is configured to provide a supply voltage (V) to the oscillation circuit (17) and is connected to a buffer capacitor (24). It has a decoupling circuit (20), which is connected on one side to the oscillation circuit (17) and on the other side to the connection device (11) for the surgical instrument (12). It has a regeneration circuit (25) by means of which energy stored in the oscillation circuit (17) can be transferred back to the buffer capacitor (24). characterized in that The regeneration circuit (25) includes a voltage multiplier circuit (C11-C23, D1-D7).

2. The generator of claim 1, wherein, The oscillating circuit is a parallel oscillating circuit.

3. The generator of claim 1 or 2, wherein, The supply circuit (22) includes a DC voltage source (23) having a buffer capacitor (24) disposed at its output.

4. The generator according to claim 3, characterized in that, The supply circuit (22) includes at least one controlled switch (26).

5. The generator according to claim 1 or 2, characterized in that, The decoupling circuit (20) is implemented by a decoupling inductor (21), which is coupled to the oscillating circuit inductor (19) in a transformer-type manner.

6. The generator according to claim 1 or 2, characterized in that, The regenerative circuit (25) includes a regenerative inductor (29) which is coupled to the oscillating circuit inductor (19) in a transformer-type manner.

7. The generator according to claim 1 or 2, characterized in that, The regeneration circuit (25) is connected to the oscillating circuit inductor (19).

8. The generator according to claim 1, characterized in that, The voltage multiplier circuit (C11-C23, D1-D7) consists of cascaded capacitors.

9. The generator according to claim 8, characterized in that, The capacitor cascade is a multi-stage cascade.

10. The generator according to claim 8 or 9, characterized in that, The capacitor cascade includes two series connections (C11-C13; C21-C23) of a plurality of capacitors (C11-C23), wherein each connection point between two capacitors (C11 / C12, C12 / C13) in one series connection (C11-C13) is connected to two diodes (D3-D6) arranged in anti-parallel, and the two diodes (D3-D6) are connected to different connection points (C21 / C22, C22 / C23) of the corresponding other series connections (C21-C23).

11. The generator according to claim 6, characterized in that, The switch (28) is positioned between the regenerative inductor (29) and the voltage multiplier circuit.

12. The generator according to claim 6, characterized in that, The ratio of the number of windings of the regenerative inductor (29) to the number of windings of the oscillating circuit inductor (19) is between two and one.

13. The generator according to claim 1 or 2, characterized in that, The generator (10) further includes a control device (B29) configured to alternately activate the excitation circuit (22) and the regeneration circuit.

14. The generator according to claim 11, characterized in that, The switch (28) is a semiconductor switch.

15. The generator according to claim 14, characterized in that, The regenerative inductor (29) is connected to ground at one end and to switch (28) at the other end.

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