A generator for operating surgical instruments.

Abstract

The present invention provides a generator having a power factor correction circuit that includes reduced assembly space and improved reliability. [Solution] The generator 11 suitable for pulse operation according to the present invention includes a power factor correction circuit 21 having an integrated control circuit. The voltage detector input of the control circuit is connected to an amplifier upstream. The amplifier can be configured such that its amplification factor has a value of 1 under a first condition and a value greater than 1 under a second condition. Furthermore, the amplification can be set to a value greater than 1 only when the voltage at the converter output is within an allowable range provided for the normal operation of the power factor correction circuit. Outside this allowable range, the amplification of the amplifier is exactly 1. In this way, the normal operation of the integrated control circuit is not hindered, especially during startup.

Description

Technical Field

[0001] The present invention relates to a generator for operating one or more surgical instruments, particularly for supplying power to such instruments.

Background Art

[0002] Electrosurgical instruments for use in human or animal patients are generally known from the prior art, as are generators for supplying such instruments. In this regard, European Patent No. 2853217 discloses a monopolar instrument and a generator to which an associated neutral electrode is connected. For energy supply, the generator can be connected to a public power grid.

[0003] The generator has a grid rectifier with a power factor correction circuit connected downstream on its input side. The power factor correction circuit is configured as a flyback converter and charges a storage capacitor to a voltage above the peak voltage of the maximum significant grid voltage. Thereby, the storage capacitor has the task of storing the energy necessary to avoid excessive voltage drops and, in the case of pulsating loads, at least to avoid voltage drops below the grid peak voltage, so that uncontrolled current does not occur in the storage capacitor through the grid rectifier and the flyback converter. A DC voltage converter is connected to the flyback converter, and the DC voltage converter has an inverter and a transformer for reliable insulation between the patient-side electrical instrument and the grid-side electricity. The DC voltage converter also includes a controlled switch and a buffer capacitor. The power factor correction circuit and the DC voltage converter include a control device that communicates with each other via a data interface. A radio frequency oscillator that provides the radio frequency treatment voltage necessary for supply to the surgical instrument is connected to the DC voltage converter.

[0004] For the implementation of power factor correction circuits, integrated circuits such as the ICE3PCS01-DS from Infineon Technologies are available, and their characteristics and application recommendations are available at https: / / www.infineon.com / dgdl / Infineon-ICE3PCS01-DS-v03_00-EN.pdf?fileId=db3a304329a0f6ee0129a67ae8c02b46. [Overview of the project] [Problems that the invention aims to solve]

[0005] When the load changes, voltage fluctuations occur on the storage capacitors of the power factor correction circuit, and limiting these fluctuations requires large-scale dimensional settings for each storage capacitor. As a result, significant space requirements arise, and errors due to charge / discharge current stress on the buffer capacitors or each capacitor block become more likely.

[0006] Starting from there, the object of the present invention is to provide a generator having a power factor correction circuit that includes reduction of assembly space and improvement of reliability. [Means for solving the problem]

[0007] This objective is achieved by the generator described in claim 1.

[0008] The generator according to the present invention serves to operate surgical instruments, i.e., to supply surgical instruments with typically radio frequency voltage and radio frequency current, and the operation of the instruments can be pulsed. Pulsed action can already be generated in that the instrument is repeatedly switched on and off again for several seconds when it is performed by a surgeon in the context of a surgeon's surgical procedure. Pulsed action can also arise from the fact that the mode selected for the operation of the instrument requires continuous switching of the RF generator's voltage on and off. This pulsing can be in the sub-Hertz range, or in the range of 1 or several Hertz. Pulsing at higher frequencies is also possible.

[0009] Generally, power factor correction circuits are based on flyback converter circuits, where the input of the flyback converter circuit is connected to a grid rectifier and its converter output is connected to at least one storage capacitor. Furthermore, the flyback converter includes an electronic switch with a control electrode, such as a field-effect transistor with a gate electrode. A control circuit is provided to control the electronic switch, and its switching signal output is connected to the control electrode, such as the gate of the field-effect transistor. In addition, the control circuit includes a voltage detector input, which is connected to the converter output, for example, via a voltage tap circuit. In this way, the control circuit receives a signal at its voltage detector input that characterizes the voltage present on the storage capacitor.

[0010] Control circuits are typically commercially manufactured and widely distributed integrated circuits configured for the operation of power factor correction circuits, and are therefore readily available on the market. However, typically, such circuits are not suitable for power factor correction circuits that supply rapidly and drastically changing loads, particularly slow-pulsating loads in the Hertz or sub-Hertz range, or for power factor correction circuits that require excessively large capacitor packets for this purpose. The present invention offers an improvement to this by placing a signal amplifier between the voltage tap circuit and the voltage detector input of the control circuit. This makes the control circuit suitable for the operation of a power factor correction circuit that can also supply loads that fluctuate considerably, particularly pulsating loads, without internal intervention.

[0011] The control circuit is preferably an integrated circuit, such as the ICE3PCS01G from Infineon Technologies, the L4985 from STMicroelectronics, the TEA2376DT from NXP, or the UCC28180 from Texas Instruments. Further ICs from these or other manufacturers may also be used.

[0012] The circuits are designed and assigned roles according to their standard applications to operate with uniform or gradually changing loads. They are also suitable for rapidly changing loads, however, transient voltage fluctuations at the converter output must be expected in the case of rapid load changes. Provided according to the present invention, with an additional amplifier connected upstream of the voltage detector input, the power factor correction circuit is also suitable for operation with rapidly changing loads while simultaneously avoiding larger voltage fluctuations, and as a result, generators can also use this power factor correction circuit to provide modes with pulsed operation. This is possible without the need to cancel transient voltage deviations with an enlarged storage capacitor (packet).

[0013] The control circuit in the shown configuration may have an overvoltage switch-off function configured to turn off the flyback converter if the voltage at the voltage detector input VSENSE exceeds a threshold. Furthermore, the control circuit may include another signal input OVP connected to the converter output via a voltage divider circuit as needed to monitor the converter output for overvoltage. It is advantageous that the amplification factor of the amplifier can be varied during the operation of the power factor correction circuit to prevent supplying inconsistent signals to the voltage detector input VSENSE and the additional signal input OVP during the start-up of the flyback converter after starting with an empty storage capacitor, i.e., during the switch-on in the case of an uncharged storage capacitor. Doing so can be avoided by preventing the control circuit from switching into error mode and turning off the power factor correction circuit.

[0014] In particular, the amplifier may include a control input configured to control the amplification. The amplification factor of the amplifier can be switched between at least two different values ​​via the control input. Preferably, the first value is equal to 1 and the second value is greater than 1. This concept is particularly suitable for ICs where amplification of the signal supplied to the voltage detector input VSENSE is not provided. In such ICs, additional signal amplification can result in inconsistent signals at different inputs of the IC. This can lead to difficulties such as error switch-off, for example, during circuit startup, especially during cold boot.

[0015] In a preferred embodiment, the control circuit includes a signal output VB_OK, characterized in that a desired setpoint voltage is provided to the converter output of the power factor correction circuit. This signal output VB_OK is preferably connected to the switching input of an amplifier. This enables the power factor correction circuit to receive an unamplified signal at its voltage detector input after switching on and thus control the flyback converter according to its specifications. When a setpoint voltage, e.g., 400 volts, is achieved at the converter output, the signal provided at the signal output VB_OK of the control circuit changes its value. This signal is supplied as a switching signal to the control input of the amplifier, thereby the amplifier includes an amplification factor greater than 1 at this time. In doing so, the loop amplification in the control loop formed by the amplifier and the control circuit is increased, and as a result, the control accuracy is improved when the setpoint voltage (e.g., 400 volts) is reached. This makes it possible to reduce the size of the capacitor or capacitor packet provided to buffer load fluctuations at the converter output, thereby saving installation space and reducing charge / discharge current, thus increasing the overall reliability of the generator. On the other hand, interference with the operation of the IC, especially during the starting phase, is avoided.

[0016] Further details and advantages of the present invention are derived from the drawings and description and related drawings and claims. [Brief explanation of the drawing]

[0017] [Figure 1] This diagram shows a generator for operating surgical instruments, using a diagram of functional blocks. [Figure 2] In addition to the generator control circuit shown in Figure 1, which represents the basic circuit diagram, this figure also shows the grid rectifier and power factor correction circuit (PFC). [Figure 3] Figure 2 shows a controllable amplifier for a power factor correction circuit in the form of a basic circuit diagram. [Figure 4] Figure 3 shows the circuit branching of a controllable amplifier. [Figure 5] Figure 2 shows a switch-on delay circuit, which is part of the power factor correction circuit. [Figure 6] This diagram illustrates the starting operation of the pulse-type operation of the power factor correction circuit. [Modes for carrying out the invention]

[0018] Figure 1 shows a medical device 10 for surgical or other effects on a patient, and a generator 11 that serves to supply the device 10. The device 10 is shown as a unipolar device to which a neutral electrode 12 must be attached to the patient. The neutral electrode 12 and the device 10 are connected to the generator 11 via wires. However, a bipolar or multipolar device may be used instead of a unipolar device, and then, if applicable, without a neutral electrode.

[0019] The generator 11 is specifically configured and suitable for operating the appliance in a mode in which the electrical load provided by the appliance, and therefore the power consumed by the appliance, changes rapidly between very low and very high values. Low values ​​can be close to 0 watts or only a few watts. High values ​​can be in the range of several hundred watts to kilowatts.

[0020] The generator 11 comprises a radio frequency oscillator 13 configured to supply the necessary power at an output 14 to which the appliance 10 and the neutral electrode 12 are connected. Additionally, the radio frequency oscillator 13 comprises a control input 15 configured to receive control impulses for controlling the radio frequency oscillator 13. For example, the control impulses can switch on and off the radio frequency oscillator or another power modulation thereof. In FIG. 1, as an example of the temporal progression of the control impulses, a square wave is shown within the block characterizing the radio frequency oscillator 13, according to which the radio frequency oscillator 13 is switched on and off at defined time intervals. Thereby, the time interval between the switch-on point and the switch-off point, i.e., between the front side and the rear side of the impulse of the square wave, can have an amount of several tens to several hundreds of milliseconds, or even one second or several seconds. In other words, the frequency of these control impulses can be within the sub-hertz or hertz range.

[0021] The system control unit 15 generates the control impulses and thus serves to define the mode in which the entire generator 11, in particular the radio frequency oscillator 13, operates. The system control unit is connected to a communication unit 16 configured to receive user input and to indicate an output. For this purpose, the communication unit 16 comprises an input element 17 in the form of, for example, a key, a button or a switch, and an output unit 18 in the form of, for example, one or more screens and / or indicator instruments and / or control lamps.

[0022] In particular, the current supply unit 19 shown at the top of the generator 11 serves to supply current not only to the radio frequency oscillator 13 but also to the system control unit 15 and the communication unit 16. The current supply unit 19 is connected on its input side to a common current supply grid and supplies current to the components of the generator 11 in a manner that has the necessary electrical reliability and with the potential insulated. This means that since the current supply unit 19 is configured in a potential insulation manner between the grid side and the patient side, the potential difference of thousands of volts between the current supply grid on one side and the patient or the instrument 10 and the neutral electrode on the other side does not cause a harmful current flow through the patient.

[0023] First, an input rectifier 20 having a grid filter connected to the power grid is part of the current supply unit 19. The input rectifier 20 is typically configured as a bridge rectifier and supplies a rectified DC voltage U , ,

[0025] at its output, and the DC voltage U r is supplied to the input of the power factor correction circuit 21. The power factor correction circuit 21 (PFC) converts this voltage into a DC voltage applied at the output that is higher than the peak voltage of the grid voltage.

[0024] The power factor correction circuit 21 has an output 22 to which the DC voltage converted by the power factor correction circuit 21 is supplied. The output 22 is connected to the input 23 of the potential insulation voltage converter 24, and its output 25 is further connected to the radio frequency oscillator to supply power to the radio frequency oscillator 13. The voltage converter 24 is configured in a potential insulation manner, that is, the input 23 and the output 25 are galvanically insulated. The insulation withstand voltage of this galvanic insulation is typically in the range exceeding 6 kV, more preferably 10 kV or 12 kV.

[0025] Optionally, a control connection, for example in the form of a data connection, can be provided between the system control unit 15 and the voltage converter 24. For example, this data connection can serve to set the amount of voltage output or other parameters at output 25. Similarly, as an option, a control connection can be provided between the system control unit 15 and the power factor correction circuit 21, for example, to pre-set a standby mode, or to activate or deactivate the power factor correction circuit 21.

[0026] The main focus of the present invention is the configuration of the power factor correction circuit 21, which is shown in Figure 2 in the form of a basic circuit diagram. The power factor correction circuit 21 comprises a flyback converter circuit 26 whose main components are an inductor 27, a diode 28 connected in series in the direction of flow, an electronic switch 29 connected from the point between them to ground, and a storage capacitor CB connected to the diode and ground. The controllable switch 29 is preferably a field-effect transistor, whose source is connected to ground and whose drain is connected to the connection point between the inductor 27 and the diode 28. Its control electrode 30 (in the case of a field-effect transistor, its gate) is connected to a control circuit 31 which is configured as an integrated circuit. A preferred component of the control circuit 31 is the circuit ICE3PCS01G manufactured by Infineon Technologies. Additional suitable integrated circuits that can be used here are available on the market, such as the L4985 from ST Microelectronics, the TEA2376DT from NXP, and the UCC28180 from TXP, as well as numerous others.

[0027] The flyback converter circuit 26 primarily corresponds to a standard circuit obtainable from the datasheet of the control circuit 31, with the exception of the features described below. In Figure 2, the connections of the control circuit 31 and its external wiring and connections, which are not necessary for understanding the circuit, are omitted. Nevertheless, the connections are available and can be wired / connected as shown in the datasheet.

[0028] Between the input rectifier 20 and the flyback converter circuit 26 is an inrush current limiting circuit 32, separately shown in Figure 5. Finally, the inrush current limiting circuit 32 is a current limiting resistor R that is short-circuited by the switching contacts of the relay 33, and as soon as each connection VB_OK of the control circuit 21 changes to a positive potential other than 0, the connected transistor 34 becomes conductive, thereby closing the contacts of the relay 33. As soon as the voltage of the converter output 22 reaches the setpoint range, a positive voltage other than 0 is applied to the connection VB_OK. The setpoint range, in this case, for a desired converter output voltage U of 400V, follows the dimensions of the voltage tap circuit 40 between 380V and 410V. The voltage tap circuit 40 is a voltage divider circuit having two or more ohmic resistors R1, R2.

[0029] The control circuit 31 further includes an overvoltage protection input OVP, which is connected to the converter output 22 via a voltage divider 41. This ensures that the voltage divider is sized to reach the switch-off limit at the overvoltage protection input OVP only when an unacceptable overvoltage is determined at the converter output 22. For example, the unacceptable overvoltage is defined by the dielectric strength of the storage capacitor CB and can be, for example, 420V.

[0030] The unique feature of the flyback converter circuit 26 compared to the standard use of the control circuit 31 is that an amplifier is placed between the voltage detector input VSENSE and the voltage tap circuit 40. The amplifier 35 has a non-inverting input connected to voltage tap point A of the voltage tap circuit 40, which consists of resistors R1 and R2. The amplifier output is inversely connected to the voltage detector input VSENSE.

[0031] In a preferred embodiment, the amplifier 35 further comprises an inverting input connected to a reference voltage. The reference voltage can be generated from a supply voltage VCC (e.g., 12V) via a series resistor to match a voltage standard, for example, in the form of a reference voltage source 36, e.g., a Zener diode. The reference voltage source 36 is configured to provide a voltage that is also applied to voltage tap point A when the voltage U is at its setpoint value. In this case, the difference between the voltage at voltage tap point A and the reference voltage is equal to 0. In addition, when the voltage U at output 22 is equal to its setpoint value, the reference voltage is equal to the voltage that must be applied to the input VSENSE of the control circuit (particularly Infineon's ICE3PCS01G). This voltage of the reference voltage source 36VSENSE, when applied to the input VSENSE, does not result in an increase or decrease in voltage U. In this embodiment, a 2.5V reference voltage source is used, for example, in the form of Analog Devices Inc.'s ADR5041BKSZ.

[0032] Amplifier 35 can be configured as an amplifier with a switchable gain, as shown in Figure 3. Amplifier 35 can be an operational amplifier, and its non-inverting input is connected to the amplifier input EA via resistor R3. The inverting input is connected to the amplifier input EB via resistor R4, and the value of resistor R4 is equal to the value of resistor R3. A resistor R5 is placed at the feedback branch between the output of the operational amplifier and resistor R4, and the ratio of resistor R5 to resistor R4 determines the amount of gain. A switch 37, in particular an electronic switch, can be provided in parallel with resistor R5, thereby short-circuiting resistor R5. Signal S can play a role in controlling switch 37, which can specifically open and close switch 37.

[0033] Figure 4 shows the implementation of switch 37 using a field-effect transistor T, the gate of which is connected to the connection VB_OK of the control circuit 31 via a resistor.

[0034] The amplification factor of amplifier 35 is "1" in the closed state, i.e., when switch 37 is conducting current. Conversely, when switch 37 is open, i.e., when current is interrupted, the amplification factor is determined by the relative ratio of resistors R4 and R5. When these two resistors are of equal magnitude, the amplification factor is "2", which is preferable in this case. However, it is also possible to provide other amplification factors.

[0035] The generator 11 described above operates as follows:

[0036] After switching the generator on, the power factor correction circuit 21 must first charge the storage capacitor CB. For this purpose, a charging current can flow through the diode D, which is initially limited by the inrush current limiting circuit 32. The signal S at connection VB_OK is 0, thereby indicating that the voltage at the converter output 22 is still outside the set voltage range. In this state, the switch 37 is closed, so the amplifier 35 has an amplification equal to 1. In other words, at the input VSENSE of the control circuit 31, the reference voltage of the reference voltage source 36 increases or decreases by the difference between the voltage at voltage tap point A and the reference voltage, according to the sine. Thus, the flyback converter circuit 26 operates in a manner common to the control amplifier internally set by the control circuit 31 in the time phase t0 shown in Figure 6.

[0037] As soon as the voltage applied to the storage capacitor CB, and therefore to the converter output 22, reaches the lower limit of the voltage tolerance range, the output VB_OK, indicating that the set voltage has been reached, changes to a positive value other than 0. By appropriately setting the voltage tap circuit 40 formed by the voltage divider or the voltage divider 41 in the connected OVP, this limit can be appropriately defined to, for example, 380 volts.

[0038] In that the inrush current limiter 32 is stopped by short-circuiting the resistor R and the switch 37 is opened, on the one hand, when the signal S reaches a predetermined switching threshold defined in this way, it switches to a positive value. As a result, the reference voltage is then increased or decreased by a twice-amplified difference between the voltages at voltage tap points A and B (Figure 2) and provided to the voltage detector input VSENSE. The voltage feedback control of the control circuit 31 and the control loop formed by the control circuit then operate with increased amplification. This amplification occurs as soon as the voltage U at the converter output falls within a specified tolerance range, such as between 380 volts and 410 volts according to Figure 6, and as long as it remains within that range. If the control circuit 31 formed by the integrated circuit is designed as a proportional controller (P-controller), a proportional-integral controller (PI-controller), or a proportional-integral-derivative controller (PID-controller), the proportional component P of the controller is increased by the present invention at least when (and preferably only when) the voltage U at the output 22 is within a predetermined tolerance range. This can be demonstrated by the signal at the output VB_OK of the integrated control circuit 31.

[0039] Next, as the amplification of amplifier 35 increases, the desired setpoint voltage of 400 volts is controlled in a feedback manner, so that, for example, transient deviations due to rapid load changes are minimized by the increase in amplification. This is shown by the comparison of time phases t1, t2, and t3 in Figure 6 after switching on. In time phase t1, a low current is consumed at the converter output 22. After a transient phase of voltage construction to the 400-volt setpoint voltage, the voltage remains constant. At the start of the subsequent time phase t2, which can have quantities such as 100 ms, 200 ms, or several hundred ms, high power, e.g., maximum power, is consumed at the converter output 22. The transition between low power and high power can be very rapid, for example, within a few milliseconds or a fraction thereof. This causes the voltage to drop for a short phase so that it is then controlled very rapidly again to the 400-volt setpoint. The visible low residual ripple is due to grid ripple and not from the control effect.

[0040] By amplifying the signals obtained from voltage tap points A and B, the voltage drop of voltage U at output 22 is significantly lower than in the absence of additional amplification with equally sized storage capacitor CB. Furthermore, the voltage rise after the end of the load period t2 is significantly lower than in the absence of amplifier 35. Therefore, using the power factor correction circuit 21 described above, a generator 11 with a radio frequency oscillator 13 that includes an operating period of very strong and short-lived changes even between zero load and full load can be realized without needing to size the storage capacitor CB larger than usual. The capacitor CB can be sized only to the values ​​necessary to accommodate the required residual ripple and the required full load, without considering the abrupt load changes considered here.

[0041] Amplifier 35 operates with an amplification greater than 1 as soon as the signal at connection VB_OK is non-zero, and as long as it is non-zero, i.e., as soon as the voltage U at converter output 22 is within the desired tolerance range, and as long as it is within that range. Outside this tolerance range, amplifier 35 operates with an amplification equal to 1, i.e., no amplification.

[0042] The generator 11 suitable for pulsed operation according to the present invention includes a power factor correction circuit 21 having an integrated control circuit 32. The power factor correction circuit includes a feedback path, through which a control loop is formed. The power factor correction circuit 21 is configured to control a switch 29 by switching impulses so that voltage fluctuations in the voltage detector input VSENSE are canceled out.

[0043] Amplifier 35 is located within a feedback path provided for voltage control, and the amplifier includes an amplification factor greater than 1. For this purpose, the voltage detector input (VSENSE) of the control circuit 31 is connected upstream to amplifier 35. This minimizes voltage fluctuations at the converter output 22 resulting from abrupt load changes. Amplifier 35 can be configured to have an amplification factor of 1 (or another invariant value) under a first condition, and a value that deviates therefrom, preferably a larger value, under a second condition. Furthermore, the amplification can be set to a value greater than 1 only when the voltage at the converter output is within the tolerance range provided for the normal operation of the power factor correction circuit 21. Outside this tolerance range, the amplification of amplifier 35 is exactly 1. This ensures that the normal operation of the integrated control circuit 31 is not hindered, especially during startup. [Explanation of symbols]

[0044] 10 devices 11 Generators 12 Neutral electrode 13. Radio frequency oscillator 14 Outputs 15 System Control Unit 16 Communication Unit 17 Input Elements 18 Indicator Elements 19. Current supply unit 20 Input Rectifiers Voltage at the output of Ur input rectifier 20 21 Power Factor Correction Circuit 22 Converter Outputs 23 Input of voltage converter 24 24 Voltage Converters 25 Output 26. Flyback converter circuit 27 Inductors 28 diodes 29 Controllable Switches / Transistors 30 Control electrodes 31 Control circuits 32. Inrush Current Limiting Circuit R is a current-limiting resistor. 33 Relay VB_OK Connection to indicate setpoint voltage 34 transistors U converter output voltage OVP Overvoltage Protection Input VSENSE voltage detector input 35 Amplifier 36 Reference voltage source VCC supply voltage 37 switches T Field-effect transistor 40 Voltage Tap Circuit 41. Voltage divider

Claims

1. A generator (11) for the operation of a surgical instrument (10), particularly for pulsed operation, The power factor correction circuit (21) includes a flyback converter circuit (26), the flyback converter circuit (26) is connected to a grid rectifier (20) at its input and to at least one storage capacitor (CB) at the converter output (22), and includes an electronic switch (29) having a control electrode (30), The converter output (22) is connected to a voltage tap circuit (40) which has a voltage tap point (A), The control circuit (31) includes a switching signal output (GATE) connected to the control electrode (30) and a voltage detector input (VSENSE), and is configured to receive a signal characterizing the voltage supplied to the storage capacitor (CB). A generator having an amplifier (35) which includes an amplifier input (EA) connected to the voltage tap point (A) and an amplifier output connected to the voltage detector input (VSENSE) of the control circuit (31).

2. The generator according to claim 1, characterized in that the control circuit (31) is an integrated control circuit that includes an internally defined relationship between the signal at the voltage detector input (VSENSE) and the switching impulse output from the control circuit (31) at the switching signal output (GATE).

3. The generator according to claim 2, characterized in that the integrated circuit is assigned a role as a non-pulse load according to the intended use.

4. The generator according to claim 1, characterized in that the control circuit (31) includes a signal output (VB_OK) configured to output a signal indicating whether the voltage (U) measurable by the converter output (22) is within a specified tolerance range.

5. The generator according to claim 1, characterized in that the control circuit (31) includes a signal input (OVP) configured to detect an overvoltage at the converter output (22).

6. The generator according to claim 5, characterized in that the control circuit (31) is configured to compare the voltages applied to the voltage detector input (VSENSE) and the signal input (OVP), and to switch off the flyback converter circuit (26) if the difference in the voltages exceeds a threshold.

7. The generator according to claim 1, characterized in that the amplifier (35) is a differential amplifier having an inverting input connected to a reference voltage source (36) and a non-inverting input connected to the voltage tap point (A).

8. The generator according to any one of claims 1 to 7, characterized in that the amplifier (35) comprises an input (S) configured to control amplification.

9. The generator according to claim 8, characterized in that the input (S) is a switching input configured to receive a switching signal in order to switch the amplification factor of the amplifier (35) between a first value and a second value.

10. The generator according to claim 8, characterized in that the first value is an amount equal to 1 and the second value is greater than 1.

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