Method for verifying power recording of RF generator of electrosurgical instrument and corresponding RF generator

Abstract

To provide a method for verifying recording of output power of an RF generator supplied to an electrosurgical instrument.SOLUTION: Disclosed is a method for verifying a power recording of an RF generator for controlling at least one electrosurgical instrument. The RF generator comprises an inverter for generating an RF signal, the inverter is supplied with a current via an inverter input part, and the RF signal having a voltage value and a current value for driving the electrosurgical instrument is emitted via an inverter output part. The method includes the steps of: directly measuring the RF signal using an RF power acquisition device, thereby recording the output power transmitted via the RF signal as directly recorded output power; recording comparative power based on power that is measured on an input side of the inverter; and comparing the recorded comparative power with the directly recorded output power, thereby verifying functioning of the RF power acquisition device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for verifying the power recording of an RF generator for controlling at least one electrosurgical instrument, and also to an RF generator using such a method. [Background technology]

[0002] To control the electrosurgical instrument, an RF generator is used that supplies the electrosurgical instrument with an RF signal having a specific power, the power depending on the specific task that the electrosurgical instrument is currently to perform.

[0003] Because these electrosurgical instruments are applied to the human body, safety issues are of paramount importance. One safety issue is ensuring that the correct power, i.e., the correct amount of power, is delivered by the RF generator. To ensure this, a redundant system is required to evaluate the delivered power. The delivered power can be used for feedback control, which in turn depends on the determined power delivered by the RF generator.

[0004] To record, i.e., estimate or measure, the output power of an RF generator supplied to an electrosurgical instrument, the voltage and current of the output signal can be measured and the corresponding output power can be calculated. Determining such power is not simple because the signal is high frequency and high voltage. This calculation requires good accuracy of the phase angle of such high frequency signals, since the phase angle between the voltage and current is important. However, this calculation can be performed by well-known FPGAs (field programmable gate arrays). Summary of the Invention [Problem to be solved by the invention]

[0005] To obtain redundant records of output power, two similar systems may be implemented. That is, two FPGAs may be used to determine the output power, and the determined output power can be verified by comparing the determined values ​​of both systems. If there is a significant difference between these two output powers determined in this way, an error must exist. Problems may arise because the methods or systems for measuring output parameters are identical or similar. The hardware, FPGA code, and software may be on both paths and have design errors that can result in the same error behavior. Therefore, comparing two such signals with the same error may not recognize the error. It is also important to note that such methods for measuring RF current and RF voltage can be complex and expensive.

[0006] It is also recognized that any additional or redundant sensors may increase certain leakage currents, but such leakage currents should be reduced rather than increased.

[0007] Therefore, a redundant system as described above has the following drawbacks: such a system may be prone to errors in terms of design and systematic errors; the redundant system also incurs costs; bypassing the corresponding path also results in high leakage currents. [Means for solving the problem]

[0008] It is therefore an object of the present invention to propose at least one solution that addresses at least one of the above-identified drawbacks. In particular, a solution is proposed for verifying the recording of the output power of an RF generator supplying an electrosurgical instrument, which avoids systematic errors, reduces costs, and avoids increased leakage currents. At least an alternative with respect to the solutions known so far should be proposed.

[0009] According to the present invention, a method is proposed as claimed in claim 1. The method is therefore directed to a method for verifying the power recording of an RF generator for controlling at least one electrosurgical instrument. The RF generator has an inverter for generating an RF signal. The inverter is supplied with a current via an inverter input. There may be a power supply for supplying the current to the inverter. The power supply may be part of the RF generator or may be an external device.

[0010] Via the inverter output, the inverter emits an RF signal having a voltage and current value for driving the electrosurgical instrument. The inverter therefore converts the input signal, which may be a DC input current, into such an RF signal. The RF signal thus drives the electrosurgical instrument, and the voltage and / or current values ​​can be set according to the actual needs of the electrosurgical instrument. The setting is also made to match a specific power value, i.e., a recorded power value.

[0011] Thus, the output power is delivered via an RF signal, and such output power is recorded as directly recorded output power by an RF power acquisition device that directly measures the RF signal. Such a power acquisition device may be an FPGA as described above. The RF signal emitted by the inverter output may also be understood as an RF output signal. Therefore, this RF output signal is measured as described. Accordingly, the power acquisition device is designed to measure the RF signal at the inverter output and estimate the power provided by the RF signal based on the RF signal.

[0012] A comparative power based on the power measured at the input side of the inverter, i.e., the inverter input, is also recorded. In particular, the power supplied by a power source connected to the inverter input can be measured. As explained, the power source at the inverter input can use a DC current, and the power at the input side of the inverter is recorded by measuring such a DC current along with the corresponding voltage. Even if the power on the input side is not supplied by a DC current, it can be supplied by a low-frequency signal such as 50 Hz or 60 Hz. For such DC signals or signals having low frequencies, inexpensive devices for measuring power are well known and available. The availability of such devices allows the comparative power to be measured in a fairly inexpensive manner.

[0013] Based on that, it is proposed to verify the functionality of the RF power acquisition device by comparing the recorded comparison power directly with the recorded output power.

[0014] In this way, a solution is proposed that avoids expensive and possibly complex additional redundant measurement systems. This solution also avoids systematic errors, since the recording of the comparative power is systematically different from the direct recording of the output power at the inverter output. The proposed solution also avoids additional leakage currents, since it avoids leakage currents at the inverter output due to the measurement of the comparative power at the input side of the inverter.

[0015] According to one aspect, it is proposed to record the input power at the inverter input and to determine the comparison power from the recorded input power minus the power dissipation. It is therefore understood that the output power should generally correspond to the input power minus any dissipated power. Accordingly, it is proposed to determine the comparison power based not only on the power measurements at the inverter input but also on the power dissipation. It has been found that such power dissipation can be calculated with good accuracy and without expensive measuring equipment. Certain values ​​influencing the dissipated power are known or can be estimated offline. Corresponding parameters are described below in connection with possible aspects of the invention.

[0016] Therefore, by taking into account the dissipated power, the comparative power can be determined without high-precision but expensive measuring equipment. In this way, good redundancy can be achieved. Therefore, a good and reliable solution can be proposed.

[0017] According to one embodiment, the functionality of the RF power acquisition device is verified if the absolute value of the difference between the recorded comparison power and the directly recorded output power is below a predetermined verification threshold. The difference is thus determined by comparing the recorded comparison power with the directly recorded output power. In particular, the verification threshold is in the range of 5% to 30%, in particular 10% to 20%, of the directly recorded output power.

[0018] In this way, there is a clear criterion for determining whether proper functioning of the RF power harvesting device can be assumed. In particular, it is proposed to use this verification threshold as a relative threshold, i.e., relative to the amplitude of the directly recorded output power.

[0019] In particular, it has been found that a value of 5% of the directly recorded output power does not indicate a malfunction, especially since the determined power dissipation value may have a discrepancy within this range due to some inaccuracy. Therefore, if such a verification threshold is selected too small, i.e., less than 5%, a false alarm problem may occur. On the other hand, an upper verification threshold value of 30% seems too ambiguous. However, it should be noted that in the case of a malfunction, a very large discrepancy will occur between the directly recorded output power and the comparison output power. Based on these findings, the lower verification threshold value can be selected to be 10%, which still provides acceptable accuracy, and the upper verification threshold value can be selected to be 20% or 25% of the directly recorded output power, which allows for the identification of malfunctions that appear without excessive discrepancies. In other words, malfunctions with a discrepancy of only slightly more than 20% or slightly more than 25% can still be identified.

[0020] According to one aspect, the power dissipation is determined as a function of at least one loss parameter. Possible loss parameters are described below. In particular, it has been found that such loss parameters are known or determinable and can be used to estimate the power dissipation and thus facilitate the calculation of the comparative power.

[0021] According to one embodiment, the loss parameter can be the modulation depth of the inverter. The modulation depth of the inverter can be defined as the ratio of the amplitude of the modulation signal to the amplitude of the DC / C voltage of the inverter, i.e., the intermediate circuit. The inverter can control a modulated current signal, which also has a voltage amplitude. Therefore, this voltage amplitude, especially the peak value of the voltage signal, is taken into consideration. Therefore, the ratio of such peak value to the amplitude of the DC / C voltage of the intermediate circuit can be considered as the modulation depth, which can also be called the modulation index.

[0022] Therefore, such modulation indices are in the range of 0 to 1. In particular, high modulation indices indicate efficient operating points. The less efficient the operating point, the higher the relative power dissipation. However, the most efficient operating point is not when the modulation indices are 1. It is more efficient when the modulation indices are in the range of 0.8 to 0.9.

[0023] Therefore, the modulation depth is always known since the exact operation of the inverter is known, which allows for an accurate estimation of the power dissipation due to modulation.

[0024] According to one aspect, the selected RF mode can be used as a loss parameter. The RF mode, or high frequency mode, can be characteristic of the selected mode of the inverter.

[0025] RF mode refers to a planned or selected setting or purpose of operation, such as a cut mode, a coagulation mode, or another mode. It is known that there are continuous modes, i.e., continuous sinusoidal oscillations, and modulated oscillations. Modulated oscillations can be interrupted oscillations, for example, two oscillations at 350 kHz, followed by a pause, then two oscillations again. Forced coagulation mode can be an example, which is repeated, for example, at about 18 kHz. Again, modulation always means amplitude modulation, i.e., modulating the voltage in the intermediate circuit, or using PWM.

[0026] The power dissipation may also vary depending on the selected RF mode, and since the selected RF mode is known, it has been found that the corresponding power dissipation can also be calculated with high accuracy given the selected RF mode.

[0027] The ambient temperature of the inverter can also be used as a loss parameter. The ambient temperature of the inverter can be measured using a temperature sensor located on the inverter casing or at a distance of less than 10 m, especially less than 1 m, from the inverter. If the inverter operates indoors, room temperature can be used as the ambient temperature. It has been found that such ambient temperature affects the temperature inside the inverter, and therefore higher temperatures can lead to higher power dissipation. It has also been found that higher ambient temperatures increase the activity of cooling vents, resulting in higher power consumption by such cooling vents. Therefore, the power required for such cooling vents can be indirectly considered by considering the ambient temperature.

[0028] According to one aspect, the component temperature of the inverter's components can be used as a loss parameter. Such component temperature may be, in particular, the temperature of semiconductors and / or circuits incorporating semiconductors, particularly circuits including semiconductor switches for generating pulse signals for generating RF signals. Such semiconductors perform the most work in converting power and dissipate power primarily as thermal power. Therefore, the temperature of such inverter components, particularly the temperature of such semiconductors or circuits, is an indicator of dissipated power. Therefore, the dissipated power can be calculated with high accuracy based on the temperature.

[0029] According to one embodiment, the inverter's switching frequency can be used as a loss parameter. It has been found that such switching frequency can affect losses, and it is proposed to take this into consideration. In particular, the inverter's switching frequency can affect transformer losses, and thus, transformer losses can be evaluated depending on the switching frequency. In particular, transformer losses, such as those described in the following paragraphs, can be evaluated. According to one embodiment, transformer losses can be used as a loss parameter. Such transformers can be used to convert the RF signal generated by the inverter to a higher voltage level required by the connected electrosurgical instrument. Because such transformer losses can be significant, the accuracy of the calculated power dissipation can be improved if the transformer losses are taken into account.

[0030] The primary current is measured in the transformer so that it can be compared with a target current and, if necessary, actively counteracted, particularly with state feedback, distortion due to resonance, which occurs, for example, at no load or at very high loads.

[0031] In addition to, or as an alternative to, the switching frequency, measured current and / or measured voltage, or other parameters, can be used to determine the losses in the transformer. Models, especially theoretical models, can also be used.

[0032] According to one aspect, at least one loss parameter is pre-recorded and assigned to a power dissipation, particularly before the inverter is put into operation, and / or at least one loss parameter is recorded and assigned to a power dissipation during operation of the inverter.

[0033] Thus, it has been found that, for at least the first feature described with respect to this embodiment, at least some of the loss parameters mentioned above can be taken into account and used to calculate power dissipation. Because some loss parameters do not change rapidly, they can be taken into account before starting the inverter. Pre-recording, particularly before the inverter enters operation, can mean particularly immediately before operation. For example, a particular operational step, which may include the surgical instrument to be used, can be selected, and loss parameters such as modulation depth can be selected individually or depending on the electrosurgical instrument to be used, or the selected RF mode is also known. Such parameters can be recorded immediately before starting operation, i.e., immediately before starting the inverter to modulate a particular signal.

[0034] On the other hand, the ambient temperature of the inverter can also be measured before operation if it does not change within a few minutes. In this way, specific consideration of such loss parameters is ensured even at the start of operation. Thus, redundant determination of the output current is ensured from the very beginning.

[0035] Additionally or alternatively, at least one loss parameter can be recorded during operation, particularly with respect to loss parameters that may change during operation. It is particularly proposed to take into account the component temperatures during inverter operation. It has been found that component temperatures, particularly of semiconductors and even of the aforementioned circuits, can change rapidly and with varying amplitudes during operation, i.e., during a single operational task. Even an operational task lasting only a few seconds, e.g., 5-20 seconds, can be long enough for the component temperatures to change significantly. Therefore, based on this knowledge, it is proposed to record the corresponding loss parameters during inverter operation, assign them to power dissipation, and take this into account when determining the comparative power.

[0036] According to one aspect, an inverter has a DC voltage input, and input power is detected from DC voltage and / or DC current measurements at the inverter input to record a comparison power. For this concept, the underlying structure includes an inverter having a DC input and an AC output. It is therefore recognized that the inverter receives DC input power, and that such input power can be used to calculate a comparison power. Such DC power can be easily measured, according to one example, by simultaneously measuring DC voltage and DC current and calculating power by, among other things, multiplying the measured voltage and current. Such multiplication is easily performed when the underlying signals are each DC signals. In this way, a good basis for input power can be achieved with simple measurement equipment and with good accuracy. Furthermore, after taking dissipated power into account, a good accuracy comparison power can be determined.

[0037] According to one embodiment, the RF power acquisition device includes an FPGA (Field Programmable Gate Array) connected to the inverter output via an isolation transformer to measure the RF signal. In combination with this, a DC measurement device is used to measure the power at the inverter input. The DC measurement device can also be used when an FPGA is not used to measure the RF signal at the inverter output.

[0038] However, the combination of an FPGA and isolation transformer at the inverter output with a DC measurement device at the inverter input has certain advantages.

[0039] An FPGA connected to the inverter output through an isolation transformer can measure the output power quickly, accurately, and usually reliably.

[0040] Therefore, it turns out that a DC measurement device can be a significantly less expensive and very reliable measurement solution if the sole purpose is to identify possible malfunctions of this measurement using an FPGA. It turns out that such a solution may not be as accurate as the FPGA used in terms of output power, but it can be accurate enough to verify whether the FPGA is working properly or if there is a malfunction of it.

[0041] Therefore, the combination of an FPGA using an isolation transformer at the output side combined with a DC measurement device at the input side provides the synergistic advantages described.

[0042] It is also important to mention that using an FPGA connected to the inverter output via an isolation transformer is very tedious and, in particular, very expensive. Therefore, to ensure the necessary redundancy, it was found that a solution using a DC measurement device on the input side can avoid the need for two measurement solutions, each with an FPGA connected to the inverter output via an isolation transformer. This combination therefore provides a good, reliable, and significantly less expensive solution.

[0043] Furthermore, the FPGA connected to the inverter via the isolation transformer on the one hand and the DC measurement device on the other hand are based on different measurement principles, thus avoiding systematic errors. For example, if an FPGA has a logical malfunction, this may also exist in the other FPGA, resulting in two erroneous measurements that provide similar but incorrect readings. In that case, comparing these two erroneous readings may not be appropriate for identifying the malfunction.

[0044] According to one embodiment, a model is used to determine the comparative power and / or to determine the power dissipation, and it has been found that by using a model all important factors and effects that lead to power loss can be taken into account without much effort.

[0045] Such a model can, among other things, take as input all the loss parameters and, based on that, simply output a specific power dissipation.

[0046] Such a model may be or may be included in a transfer model of the inverter that determines losses depending on the particular mode of the inverter.

[0047] The model can be designed using known conditions, such as the power dissipation of the inverter as a function of modulation depth and / or as a function of the selected high frequency mode. The power dissipation of the inverter components, especially the semiconductors, is often known, or at least models of such semiconductors are known, since semiconductors are usually designed using simulations based on very accurate models of the semiconductors. Such models or simplified models based thereon can be used.

[0048] Additionally or alternatively, power dissipation can be measured while recording the described loss parameters. This can be done offline before operating the RF generator. Complex simulations can also be used to test the entire RF generator, including the attached electrosurgical instrument, and based on such complex simulations, the behavior of power dissipation as a function of the power loss parameters can also be simulated. Based on this, specific models can be designed to model power dissipation.

[0049] It is also possible to constantly measure the dissipated power and, based on this, design a model by online learning, or at least validate the model by online learning.

[0050] The comparative power can be calculated based on the power dissipation determined by using such a model. However, the calculation of the comparative power can also be performed by such a model. In other words, the calculation of the comparative power can be integrated into the functionality of the model. In that case, the model can output the comparative power directly. However, the power dissipation can also be output by such a model as an additional value that can be used to verify the correct operation of the model.

[0051] According to one aspect, an adaptive and / or self-learning estimation method and / or estimation model with estimation parameters is used to estimate the comparison power. It has therefore been found that a method for estimating the comparison power can provide increasingly improved, in particular increasingly accurate, results by providing it as an adaptive and / or self-learning estimation method. This method can be implemented in a model, which can then be adaptive and / or self-learning accordingly.

[0052] Such a method or model has estimation parameters that are used to estimate, in particular, the power dissipation and, based on that, to estimate or calculate the comparative power. This may also be based on the power measured at the input side of the inverter. In a simple example, one estimation parameter is a coefficient that can be multiplied by the recorded input power to calculate a portion of the dissipated power. The coefficient has a starting value of 0.1, i.e., 10%, and can be adapted during operation. The dissipated power can be calculated by adding that portion of the dissipated power to a further portion of the dissipated power.

[0053] It has also been found that the estimation of comparative power, and in particular the estimation of power dissipation required for this, can be part of providing redundant power measurements or redundant recording of power, i.e., comparative power is redundant to highly accurate power measurements, in particular measurements using FPGAs as described above. It has therefore been found that such measurements, i.e., measurements or estimates of directly recorded output power, can also be used for adaptation and / or self-learning for the recording or estimation of comparative power.

[0054] The estimation parameter may be any of the parameters that describe the relationship between any of the loss parameters mentioned above. Thus, the estimation parameter may be the relationship between the modulation depth of the inverter and the resulting power dissipation. The estimation parameter may also be the relationship between the selected RF mode and the resulting power dissipation. The estimation parameter may also be the relationship between the ambient temperature of the inverter and the resulting power dissipation. The estimation parameter may also be the relationship between the component temperature and the resulting power dissipation.

[0055] It should be noted that the power dissipation taken into account to calculate the comparison power based on the power measured on the input side may be the sum of the aforementioned power dissipations resulting from each of the aforementioned loss parameters. Naturally, additional power dissipation portions may be added. In particular, there may be a residual power dissipation that covers all power dissipations not mentioned and / or not considered. Transformer losses may also be added to the power dissipation. Therefore, the power dissipation used to calculate the comparison power based on the power measured on the input side may also be referred to as the total power dissipation. In other words, the comparison power is determined by subtracting such total power dissipation from the recorded input power.

[0056] One estimation parameter can be the relationship between any explicitly considered power dissipation portions and the residual power dissipation. For example, suppose the explicitly considered power dissipation portions total 100 W, but in reality the total power dissipation is known to be 110 W. In this example, the estimation parameter describing the relationship between the explicitly considered power dissipation portions and the residual power dissipation would be 0.1 according to this illustrative example. Alternatively, the estimation parameter could be the relationship between the explicitly considered power dissipation portions (totaling 100 W) and the total power dissipation (110 W in this example), such that the estimation parameter would be 1.1 according to the example.

[0057] In particular, it is proposed that the comparison power is estimated based on initial or previously adapted values ​​of the estimation parameters. Thus, when the device, model or method is first started, there are initial estimation parameters with default values. Thereafter, the estimation values ​​can be further adapted, and thus the actual values ​​of these estimation parameters become the basis for further adaptation and / or self-learning.

[0058] Furthermore, the estimated comparison power is compared with the directly recorded output power. If the functionality of the RF generator is verified according to the comparison result, i.e., if it is found that there is no malfunction, the directly recorded output power is identified as the verified output power. Here, the underlying idea and knowledge is that unless there is a malfunction, the directly recorded output power value is assumed to be very accurate. Therefore, if it is found that there is no malfunction, the directly recorded output power value is assumed to be very accurate.

[0059] Therefore, it is further proposed to adapt the estimation parameters to match the estimated comparison power to the verified output power.

[0060] In the example above, and therefore for illustrative purposes only with respect to a single estimation parameter, the estimation parameter to account for residual power dissipation was 1.1. This calculated a total power dissipation of 110 W, out of the 100 W explicitly accounted for. However, if a comparison with the directly recorded output power reveals that the total power dissipation is actually 120 W, the estimation parameter described above can be changed from 1.1 to 1.2. However, rather than completely changing this parameter, it is suggested to asymptotically move it toward this new value. Based on the example above, the value of 1.1 can be corrected by 10% of the total discrepancy. Therefore, the value can be changed from 1.1 to 1.11. If the same discrepancy occurs again next time, it can be further corrected from 1.11 to 1.12. This has a sort of filtering effect from the identified discrepancy to the resulting adjustment of the estimation parameter.

[0061] According to the present invention, an RF generator is also proposed. Such an RF generator is designed to control at least one electrosurgical instrument connected to the RF generator. The electrosurgical instrument may be part of the generator or may be a separate element. However, certain functions correspond to the situation when the electrosurgical instrument is connected. It is also possible to connect different electrosurgical instruments in parallel or in series to the same or different output plugs of the RF generator.

[0062] The RF generator is adapted to verify a power record of the RF generator, the recorded power being the power delivered to an electrosurgical instrument connected to the RF generator during operation.

[0063] The RF generator has an inverter for generating an RF signal that can be supplied to the electrosurgical instrument to provide the electrosurgical instrument with energy and a specific signal to operate the electrosurgical instrument.

[0064] In operation, the inverter is supplied with current via the inverter input and emits via the inverter output an RF signal having voltage and current values ​​for driving the electrosurgical instrument. The RF generator is also adapted to perform the following steps:

[0065] In one step, the RF generator records the output power delivered via the RF signal by directly measuring the RF signal with the RF power acquisition device. This output power is referred to as the directly recorded output power. A further step is to record a comparison power, which is based on the power measured at the input of the inverter. A further step is to verify the functionality of the RF power acquisition device by comparing the recorded comparison power with the directly recorded output power.

[0066] The RF generator may be adapted to perform this verification by having an RF controller adapted to perform and / or control steps for verifying the power recording. The steps, particularly steps according to any of the above-described aspects, may be performed using a computer program implemented in the RF controller, which may of course also perform further functions, particularly controlling the RF generator to provide an RF signal for operating a connected electrosurgical instrument.

[0067] According to one embodiment, the RF generator, in particular its RF controller, is adapted to perform at least one method according to any one embodiment described above with respect to the method for validating the power recording.

[0068] The invention will now be described by way of example on the basis of embodiments with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0069] [Figure 1] FIG. 1 is a schematic diagram of an RF generator for controlling at least one electrosurgical instrument. [Figure 2]FIG. 10 is a diagram showing input power and output power versus dissipated power. [Figure 3] 1 is a simplified flowchart of a method according to at least one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0070] 1 shows a schematic diagram of an RF generator 100 having an electrosurgical instrument 102 connected for operation on tissue 104, which is shown only symbolically. RF generators for controlling at least one electrosurgical instrument are generally quite complex and comprise many elements. However, the illustrated RF generator 100 illustrates only a few basic elements useful for understanding the present invention.

[0071] The RF generator 100 comprises a DC power supply 106 for supplying DC power to the RF generator 100. The DC power supply 106 may be connected at its power input 108 to a standard power supply grid providing a voltage of 110V or 230V.

[0072] The DC power supply 106 basically rectifies an input voltage received at its power supply input 108 into a DC signal and outputs it at its power supply output 110. The DC power supply 106 may also comprise means for varying the voltage amplitude at its power supply output 110. The power supply output 110 is connected to a DC input 112 of an inverter circuit 114. The inverter circuit 114 comprises a DC intermediate circuit 116 having an intermediate capacitor 118. The inverter 114 comprises four semiconductor switches 121-124 connected to the intermediate circuit 116 to generate an AC output signal at an AC output 126 of the inverter circuit 114. The generation of such an AC output signal is based on the DC voltage in the DC intermediate circuit 116. The semiconductor switches 121-124 may be IGBTs. The semiconductor switches 121-124 generate an RF output signal by pulse modulation, such as PWM. However, different circuits and modulation methods can be used.

[0073] To control the modulation, the four semiconductor switches 121-124 are controlled by an inverter controller 128. The inverter controller 128 is therefore connected to each of the semiconductor switches 121-124 and therefore has any information related to the modulation, such as the modulation frequency and modulation depth, by controlling the semiconductor switches. The inverter controller 128 may also have detailed knowledge of the temperature of the inverter circuit, or even of each of the four semiconductor switches 121-124. For that purpose, a temperature sensor may be provided, which is not shown in FIG. 1 in order to keep the schematic structure simple.

[0074] An RF transformer 130 is connected to the AC output 126 of the inverter circuit. The RF transformer 130 converts the AC signal at the AC output 126 to a higher voltage and provides this higher voltage RF signal to a generator output 132. The electrosurgical instrument 102 is connected to the generator output 132 and receives and operates using this high voltage RF signal.

[0075] In operation, inverter circuit 114 is controlled to provide an RF signal having a voltage amplitude as high as required at generator 132. A value for controlling the signal at generator output 132 determines the output power P delivered to electrosurgical instrument 102 at generator output 132. OUT is.

[0076] Output power P OUT It is important that the output power setting corresponds to the corresponding output power setting that is delivered to the electrosurgical instrument and therefore to the tissue 104 shown, which is part of the human body. It is important that the output power provided is correct, as providing too much power can be dangerous.

[0077] To ensure this, there is a current sensor 140 and a voltage sensor 142. Based on these measured current and voltage signals, a power calculation unit 144 calculates the corresponding output power P OUTand current sensor 140, voltage sensor 142 and power calculation unit 144 can be understood to form RF power acquisition unit 146. However, it is also possible to use the measured current and voltage signals and calculate the output power based on these signals in a section of inverter controller 128 or in a section that is part of another controller of the RF generator.

[0078] In either case, such RF power harvesting devices 146 are very complex and expensive, in part because the current sensor 140 and voltage sensor 142 measure at high voltage levels, making it important to isolate these sensors from the connected power calculation section 144 or other sections of the calculation section that may be part of a separate calculation unit or another controller.

[0079] Since it is important to ensure that the correct power is supplied, redundancy is often necessary. Instead of measuring the output power directly with a second device similar to the RF power acquisition device 146, it is proposed to measure the power at the input of the RF generator 100. This is shown by a DC sensor 150, but again only diagrammatically. Such a DC sensor 150 may be a current sensor measuring DC current. The DC voltage at the power supply output 110 may also be measured. Based on this, the input power P IN can be calculated as the input power of the RF generator. However, the input power can also be assumed to be a constant voltage amplitude in the intermediate circuit or known by the inverter controller 128.

[0080] In either case, such an input power P at the input of the inverter IN can be measured much more easily, i.e., the output power P OUT can be measured using a cheaper sensor than when measured using RF power acquisition device 146.

[0081] However, the input power P INis the output power P due to the power dissipation of some elements. OUT It has been found that the power dissipation is higher than . Therefore, it is proposed to determine such a power dissipation, which is illustrated by way of example in FIG. 1. The inverter controller 128 knows the control scheme of the four semiconductor switches 121-124 and also knows the modulation depth of the inverter. As mentioned above, the inverter controller may also have information about the temperature of the semiconductor switches 121-124, so that it can calculate the power dissipation of these switches.

[0082] However, it is also possible to determine the power dissipation of the semiconductor switches based on known control schemes for the inverter, and therefore the semiconductor switches, and based on the ambient temperature. DI The dissipated power of the RF transformer 130 can be calculated as follows: There is also a large power dissipation expected in the RF transformer 130. Considering such power is also shown in FIG. 1, and therefore the RF-transformer 130 is DT In this way, all the power dissipation parts are collected, and according to the example in Figure 1, the inverter P DI Power dissipation and transformer P T The contribution of the total power dissipation P D This is done in summing element 152. This is for illustrative purposes only, other power dissipation portions may be considered in addition, but it is also possible that one of the mentioned power dissipation portions is so small that it can be ignored, or so nearly constant that it can be considered a constant value.

[0083] However, in the subtraction element 154, the total dissipated power P D is the input power P IN The result is the comparison power P C Therefore, in logic block 156, the comparison power P C and output power P OUTThis logic block 156 may be a single separate block or may be implemented in one of the illustrated or other controllers.

[0084] In particular, the logic block can be implemented in the general control of the RF generator or in the inverter controller 128. In this logic block 156, the comparison power P C is the output power P OUT However, some uncertainty can be tolerated, so the comparison in the logic block checks whether both power values ​​are approximately the same. One way to do this would be to subtract one from the other and check whether the difference is below a predetermined tolerance. Such a predetermined tolerance could be in the range of 5% to 20% of the output power or set power.

[0085] Thus, in the logic block, the result of the comparison is either NO or YES, so if the result of the comparison is NO, the generator can be stopped, and if the comparison is YES, the generator can continue to run.

[0086] Fig. 2 shows a simplified illustration of the underlying idea of ​​the present invention. According to Fig. 2, an RF inverter 200 receives an input signal 202 with an input power P IN As a result, the output power P OUT However, an RC output signal 204 having an output power P OUT is the input power P IN is smaller than the total dissipated power P D The dissipation is represented by a single dissipation signal 206. However, there may be multiple elements or components or locations within the inverter that consume a portion of the dissipated power.

[0087] A method according to one embodiment is illustrated in the flowchart of FIG. 3, which shows a method flowchart 300. At the start of the illustrated method, the output power P OUTis recorded. Meanwhile, the input power P IN is recorded at the input of the RF generator according to input power recording step 304, and the power dissipation P according to dissipation power recording step 306. D is also recorded.

[0088] Dissipated power or power dissipation is often not a single power, but an inverter P DI Power dissipation and transformer P DT , which is the sum of the various dissipated power parts as described by way of example with respect to FIG. 1 .

[0089] In the subtraction step 308, the total dissipated power P D is the input power P IN The result is the comparison power P C This becomes:

[0090] In the comparison step 310, the output power P OUT and the comparison power P C are compared. This can be done by subtracting both values ​​from each other and checking, depending on the absolute value of the result, whether the result is less than a predefinable threshold. In that case, the comparison is true or YES, since there is only a small difference, i.e. a difference less than the aforementioned threshold.

[0091] If the comparison in the comparison step 310 shows that both values ​​are not the same, ie the difference is higher than the aforementioned threshold, the generator is immediately stopped according to a first stopping step 312 .

[0092] The comparison is positive, i.e., the output power P OUT and comparison power P C If they are similar, the result is YES, and the output power is equal to the set power P SET may further be checked whether it is similar to the output power P in accordance with a value check step 314. This comparison may be performed in a similar manner as described with respect to the comparison step 310. Thus, both estimated power values, i.e., the output power P OUT and comparison power P Care similar, but also whether the value is the desired amount, i.e., the amount set by the actual control of the electrosurgical instrument, so that if the result of the value check step is YES, then according to confirmation step 316, all is well and so the RF generator and electrosurgical instrument can continue to operate.

[0093] On the other hand, if the result of the value checking step is negative, the generator is stopped according to a second stopping step 318 .

[0094] According to the present invention, the following problem is identified: To ensure proper / regulated output of RF power, current, and voltage, the monitors of RF voltage and RF current are redundant, so the output parameters are determined and compared in approximately the same procedure.

[0095] If there is a difference between the measured RF current and / or RF voltage between the primary and redundant RF monitors, a fault condition exists.

[0096] By implementing measurement methods to determine output parameters and / or using the system identically (this refers to both hardware, FPGA code, and software if an FPGA is used), design errors in both paths can result in the same malfunction. Also, implementing RF current and RF voltage measurements is complex and expensive. Furthermore, the additional sensors in the application circuitry result in higher leakage currents, which must be minimized.

[0097] Therefore, known systems may have the following drawbacks:

[0098] Known systems may be prone to design and systematic errors.

[0099] Known solutions also increase costs, since the measurement system has to be implemented twice.

[0100] The leakage current can be high due to the additional bridging of the isolation distance by the sensor.

[0101] Based on this, the following ideas and solutions are proposed.

[0102] Verification of the output parameters should be performed indirectly via the inverter input parameters and known losses. The input DC power (current, voltage) is determined and set in relation to the RF output power, taking into account the losses of the RF inverter, e.g., thermal and electrical losses. This is shown by the following equation: ■ HF-output =■ DC-Input +■ Loss

[0103] Power dissipation depends on various factors such as RF modulation level, RF mode, ambient temperature, etc. These factors are determined during development and included in the calculations.

[0104] If there is a discrepancy between the calculated output power (which can be referred to as the PHF output) and the actual output power (calculated from the RF output parameters), an error case exists (e.g., a faulty voltage sensor) and the system can address this.

[0105] The proposed solution has the following advantages:

[0106] The expensive design of an RF current-voltage sensor (faster analog-to-digital converter or ADC and field programmable gate array (FPGA)) and an additional microcontroller unit (MCU) can be avoided.

[0107] Lower leakage currents can be achieved because fewer sensors need to bridge the application and secondary circuits. [Explanation of symbols]

[0108] 100 RF Generator 102 Electrosurgical Instruments 104 Organization 106 DC power supply 108 Power input section 110 Power output section 112 DC input section 114 Inverter circuit 116 DC intermediate circuit 118 Intermediate Capacitor 121~124 Semiconductor switches 126 AC output section 128 Inverter Controller 130 RF transformer 132 Generator output section 140 Current Sensor 142 Voltage Sensor 144 Power calculation section 146 RF Power Acquisition Device 150 DC sensor 152 Additive Elements 154 Subtraction Elements 156 logical blocks 200 RF Inverter 202 Input Signal 204 RC output signal 206 Single Dissipative Signal

Claims

1. 1. A method for verifying power logging of an RF generator for controlling at least one electrosurgical instrument, comprising: the RF generator having an inverter for generating an RF signal; the inverter is supplied with current via an inverter input and emits via an inverter output the RF signal having voltage and current values ​​for driving an electrosurgical instrument; The method comprises: recording the output power delivered via the RF signal as directly recorded output power by directly measuring the RF signal with an RF power acquisition device; recording a comparison power based on the power measured at the input of the inverter; and verifying functionality of the RF power acquisition device by comparing the recorded comparison power with the directly recorded output power.

2. input power is recorded at the inverter input; The comparison power is determined from the recorded input power minus the power dissipation.

2. The method of claim 1.

3. If the absolute value of the difference between the recorded comparison power and the directly recorded output power is below a predetermined verification threshold, the functionality of the RF power acquisition device is verified, in particular The verification threshold is in the range of 5% to 30%, in particular 10% to 20% of the directly recorded output power.

3. The method according to claim 1 or 2.

4. The power dissipation a modulation degree of the inverter; a selected RF mode; the ambient temperature of the inverter; component temperatures of the inverter components; a switching frequency of the inverter; and Transformer losses and 3. The method according to claim 1, wherein the loss parameter is determined in dependence on at least one of the loss parameters from a list comprising:

5. At least one loss parameter is specifically, pre-recorded and allocated power dissipation before the inverter is put into operation; and / or During operation of the inverter, the power dissipation is recorded and assigned to 3. The method according to claim 1 or 2.

5. the inverter having a DC voltage input; One or the input power from a DC voltage measurement and / or a DC current measurement at the inverter input is detected to record the comparison power.

3. The method according to claim 1 or 2.

6. the RF power harvesting device comprises an FPGA connected to the inverter output via an isolation transformer to measure the RF signal; and / or A DC measurement device is used to measure the power at the input of the inverter.

3. The method according to claim 1 or 2.

7. to determine the comparison power; and / or To determine the power dissipation The model is used 3. The method according to claim 1 or 2.

8. An adaptive and / or self-learning estimation method and / or estimation model with estimation parameters is used to estimate said comparative power, in particular the comparison power is estimated based on initial or previously adapted values ​​of the estimation parameters; the estimated comparison power is compared to the directly recorded output power; if the functionality of the RF generator is verified according to a result of the comparison; the directly recorded output power is identified as a verified output power; The estimation parameters are adapted to match the estimated comparison power to the verified output power.

3. The method according to claim 1 or 2.

9. an RF generator for controlling at least one electrosurgical instrument, adapted to verify a power record of said RF generator, the RF generator having an inverter for generating an RF signal; the inverter, during operation, is supplied with current via an inverter input and emits, via an inverter output, an RF signal having voltage and current values ​​for driving the electrosurgical instrument; The RF generator: recording the output power delivered via the RF signal as directly recorded output power by directly measuring the RF signal with an RF power acquisition device; recording a comparison power based on the power measured at the input of the inverter; and verifying functionality of the RF power acquisition device by comparing the recorded comparison power with the directly recorded output power.

10. the RF generator comprising an RF controller for performing and / or controlling the step of verifying the power record; The RF generator, in particular the RF controller, is adapted to perform the method according to any one of claims 1 to 9.

10. The RF generator of claim 9.

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