JP6696799B2 - Engine operating method and closed loop control system - Google Patents

Description

  The present invention relates to a method of operating an engine when gaseous fuel burns. The invention further relates to a closed loop control system for implementing the method.

  From practice, an engine in which gaseous fuel such as natural gas burns as fuel is known. The engine can be a pure gas engine or also a so-called dual fuel engine. In the dual fuel engine, liquid fuel such as diesel or heavy oil burns in the liquid fuel operation mode, and gaseous fuel burns in the gas fuel operation mode. As the gaseous fuel burns in the engine, supercharged air is supplied on the one hand and gaseous fuel on the other hand, from which a gas / air mixture is formed, which gas / air mixture forms for combustion in the engine. Supplied to the cylinder. The supercharged air is supplied through the supercharged air system at a closed loop controlled supercharging pressure, and the gaseous fuel is supplied through a corresponding fuel supply system at a closed loop controlled gas pressure. That is, the supply is performed so that a desired pressure difference is formed between the supercharging pressure of the supercharged air and the gas pressure of the gaseous fuel. For this purpose, the gas pressure for the gas pressure closed loop control depends on the boost pressure target value of the boost pressure closed loop control and also on the pressure difference target value between the boost pressure and the gas pressure. The target value is determined. The quality of gas pressure closed loop control is limited in the procedure of determining the gas pressure target value, which is known from practice, and which depends exclusively on the boost pressure target value and the pressure difference target value. In that respect, the pressure difference between the supercharging pressure and the gas pressure can be closed-loop controlled only with a limited quality. Moreover, during load changes, only limited quality gas pressure closed loop control is possible.

  Starting from this, the object of the invention is to provide a new method for operating an engine and a new closed-loop control system. This problem is solved by the method according to claim 1. According to the present invention, the gas pressure target value is further determined depending on the boost pressure current value of the boost pressure closed loop control. That is, the preliminary control component (Vorsteueranteil) and the closed loop control component related to the gas pressure target value are determined depending on the current boost pressure and the target boost pressure value. In order to determine the pressure target value, the pressure difference target value is corrected. The present invention proposes to determine a gas pressure target value for gas pressure closed loop control through a preliminary control component and a closed loop control component. This makes it possible to improve the quality of the gas pressure closed-loop control, especially during load changes, and finally to adjust the pressure difference with a higher quality or accuracy.

  According to an advantageous further development of the invention, the pre-controlling component for determining the gas pressure setpoint is configured such that the slope of the pre-control ramp is determined in dependence on the temporal derivation of the current supercharging pressure. It is determined that the end point of the pre-control ramp is determined depending on the target value. A pre-control component through such a pre-control ramp allows high quality gas pressure closed loop control, especially during load changes.

  According to an advantageous further development of the invention, the closed-loop control component for determining the gas pressure setpoint is such that the boost pressure present value determines the input variable for the first control device of the first closed-loop control circuit. Is determined so as to be corrected by the preliminary control component and the closed loop control component, and the output variable of the first control device corresponds to the closed loop control component for determining the gas pressure target value. Thereby, the quality of the gas pressure closed loop control can be further improved. The pre-control ramp or the pre-control component influences the closed-loop control component, which reduces the load on the control device which supplies the closed-loop control component with respect to the gas pressure target value.

  According to an advantageous further development of the invention, the gas pressure setpoint is corrected with the gas pressure present value in order to determine the input variable for the second control device of the second closed-loop control circuit. The output variable of the second control device is corrected with the gas pressure target value in order to determine the control variable for the gas pressure control path (Gasdruckregelstrecke) of the gas pressure closed loop control. The current gas pressure value is corrected exclusively by the load pressure target value, processed in the second closed loop control circuit, and not supplied to the first closed loop control circuit. By separating both closed loop control circuits with respect to the gas pressure present value, the quality of the gas pressure closed loop control can be improved, especially during load changes.

  According to an advantageous further development of the invention, the pressure difference setpoint is determined as a function of the gas quality. By determining the pressure difference setpoint as a function of the gas quality, the quality of the gas pressure closed loop control can be further improved.

  A closed loop control system for carrying out the method is defined in claim 8.

  Preferred further configurations of the invention emerge from the subclaims and the following description. Embodiments of the present invention will be described in detail with reference to the drawings without being limited thereto. Shown are the following figures.

1 is a block diagram of an engine configured as a dual fuel engine. It is a block diagram of a cylinder of an engine. It is a block diagram of the closed loop control system for operating an engine. 6 is a graph for clarifying one embodiment of the present invention.

  The present invention relates to a method of operating an engine when gaseous fuel burns, and a closed loop control system for implementing the method.

  FIG. 1 exemplarily shows a block diagram of a dual fuel engine 10 including a plurality of cylinders 11. In the liquid fuel operation mode, the liquid fuel FK exclusively burns in all the cylinders 11. In the gas fuel operation mode, in all cylinders 11 of the dual fuel engine, the gas fuel GK burns exclusively using the ignition fluid ZF for igniting the gas fuel GK.

  In the embodiment shown in FIG. 1, the dual fuel engine 10 is provided with an exhaust gas turbocharger 12, and the exhaust gas AG generated when the fuel burns in the cylinder 11 of the dual fuel engine 10 is The exhaust gas AG is supplied to the turbine 13 of the exhaust gas turbocharger 12, whereby the exhaust gas AG expands in the turbine 13 and mechanical energy is obtained. The mechanical energy is used in the compressor 14 of the exhaust gas turbocharger 12 to compress the supercharged air LL to be supplied to the cylinder 11 of the dual fuel engine 10 for combustion of fuel. At that time, in the gas fuel operation mode, a gas-air mixture is formed from the supercharged air LL and the gas fuel GK, and the mixture is supplied to the cylinder 11 and ignited by the ignition fluid ZF.

  FIG. 2 shows further details of the dual-fuel engine 10 in the region of the cylinder 11, the piston 15 of the cylinder 11 being able to move up and down via the connecting rod 16. In the liquid fuel operation mode, the liquid fuel FK is introduced into the combustion chamber 26 of the cylinder 11 through the fuel injector 19, the supercharged air LL is introduced through the intake valve 17, and the exhaust gas AG generated during combustion is exhausted through the exhaust valve 18. Is discharged from the combustion chamber 26. The liquid fuel FK is supplied to the injector 19 through the fuel pump 20.

  In the gas fuel operation mode, the air-fuel mixture of the supercharged air LL and the gas fuel GK is introduced into the combustion chamber 26 of the cylinder 11 via the intake valve 17, and the ignition fluid is used to ignite the gas-air mixture. ZF is used, and the ignition fluid is supplied from the ignition fluid pump 23 and the ignition fluid storage device 22 to the cylinder 11 through the ignition fluid injector 21. That is, in the embodiment of FIG. 2, it is supplied to a further combustion chamber 24 of the cylinder 11 which is connected to the combustion chamber 26 via at least one connecting conduit 25. It should be pointed out that it is also possible to introduce the ignition fluid ZF directly into the combustion chamber 26.

  The present invention relates to details in the dual fuel engine 10 of FIGS. 1 and 2 such that the gaseous fuel operating mode in which gaseous fuel burns in the engine can be improved.

  However, it is pointed out that the present invention is not limited to use with dual fuel engines, but may also be used with gas engines dedicated to the combustion of gaseous fuels. Even in such a pure gas engine, the mixture of the supercharged air LL and the gaseous fuel GK is supplied to the cylinder of the gas engine, and the exhaust gas AG generated during combustion is discharged from the cylinder of the gas engine. ..

  FIG. 3 is a block diagram of the closed loop control system 27, in which the gaseous fuel GK is subjected to a predetermined closed loop control in order to form a gas / air mixture in the engine to be operated. Can be supplied at different gas pressures. That is, the supply is performed so that a desired pressure difference is maintained or formed between the gas pressure of the gaseous fuel GK and the supercharging pressure of the supercharging air LL.

  The supercharged air LL for the gas / air mixture is supplied by the supercharged air system and the supercharged air closed loop control provides a predetermined closed loop controlled supercharging pressure for the supercharged air LL.

  The supercharging pressure closed loop control, which is not shown in detail in FIG. 3, is based on the supercharging pressure target value 28 and the supercharging pressure present value 29 visualized by blocks in FIG. Generates a control variable based on the control deviation between the boost pressure target value 28 and the boost pressure present value 29, whereby the boost pressure present value 29 is led to the boost pressure target value 28. .. As already explained, the details of the boost pressure closed loop control are not shown in FIG.

  Like supercharged air, the gas or gas fuel GK used to supply the gas / air mixture is supplied by the gas supply system at a closed loop controlled gas pressure, and the gas pressure closed loop control 34 of the gas supply system is The gas pressure target value 30 is compared with the gas pressure present value 31, and the control variable for the gas pressure control path 33 of the gas pressure closed loop control 34 is determined accordingly. The gas pressure closed loop control 34 determines the control variable 32 so that the gas pressure present value 31 approaches the gas pressure target value 40 or follows the gas pressure target value. The gas pressure target value 30 is determined depending on the boost pressure target value 28, the boost pressure current value 29, and the pressure difference target value 35. Details regarding this are described below.

  The determination of the gas pressure target value 30 for the gas pressure closed loop control 34 depending on the boost pressure current value 29, the boost pressure target value 28, and the pressure difference target value 35 depends on the boost pressure current value 39. And a sub-control component 36 on the one hand and a closed-loop control component 37 on the other hand as determined with respect to the gas pressure target value 30. And the closed-loop control component 37 is corrected with the pressure difference target value 35 to determine the gas pressure target value 30.

  In FIG. 3, the preliminary control component 36 and the temporal derivation of the preliminary control component 36 at the first addition point 39 obtained by the differentiator 38 are corrected by the closed loop control component 37, and the auxiliary variable 40 is determined. That is, the auxiliary variable 40 is corrected by the pressure difference target value 35 in order to determine the gas pressure target value 30 at the second addition point 41.

  The preliminary control component 36 for the gas pressure setpoint 30 is determined such that the gradient 43 for the preliminary control ramp 44 is detected, depending on the temporal derivation of the current boost pressure 29 obtained by the differentiator 42. The end point of the preliminary control ramp 44 is determined depending on the boost pressure target value 28. As is apparent from FIG. 3, the slope 43 for the pre-control ramp 44 is detected, on the one hand, dependent on the temporal derivation of the boost pressure present value 29 formed in the differentiator 42, and on the other hand. Dependent on a predetermined minimum slope 45 for the pre-control ramp 44. A predetermined minimum value 45 and a maximum value from the temporal derivation of the supercharging pressure present value 29 formed by the differentiator 42 are used as the gradient 43, respectively.

  The closed loop control component 37 for the gas pressure target value 30 is determined such that the boost pressure present value 29 is corrected by an auxiliary variable 40 that is dependent on the preliminary control component 36 and the closed loop control component 37. That is, it is determined by forming the difference 46 between the boost pressure present value 29 and the auxiliary variable 40 dependent on the preliminary control component 36 and the closed loop control component 37. Dependent on this difference 46, the controller 47 of the first closed-loop control circuit detects the closed-loop control component 37 as an output variable. According to FIG. 3, the first controller 47 has a proportional component 48 and an integral component 49, so that the first controller 47 is configured as a PI controller and the PI controller is proportional. By superposing the component 48 and the integral component 49 at the addition point 50, the closed loop control component 37 regarding the gas pressure target value 30 is output.

  As already explained, the gas pressure target value 30 is dependent on the preliminary control component 36, the closed loop control component 37, and the pressure difference target value 35, and the block 51 in FIG. 4 is dependent on the engine operating state 52. It has been clarified that other gas pressure target values relating to the gas pressure closed loop control 34 may be output instead of the gas pressure target value 30 detected by the method described above. The block 51 is a selection block, which is detected by the above-described method depending on the operating state 52 of the engine and has the supercharging pressure present value 29, the supercharging pressure target value 28, and the pressure difference. The gas pressure target value 30 that is dependent on the target value 35 is output, or the alternative gas pressure target value 30 ′ or 30 ″ or 30 ″ ′ is output.

  When the leak test function 53 is active, the selection block 51 outputs a constant gas pressure target value as the gas pressure target value 30 ″ ″.

  If a pressure increase is required via block 54, the selection block 51 selects the gas pressure target value 30 ″ as a parameterizable ramp for the gas pressure target value at the pressure increase, which is a dual fuel engine. Then, it is the case before the liquid fuel operation is switched to the gas fuel operation.

  If a pressure drop is required via block 55, the selection block 51 selects a parameterizable ramp for pressure drop as the gas pressure setpoint 30 ', which in a dual fuel engine is gas fueled. This is the case when the switching from the mode to the liquid fuel operation mode is completed.

  The gas pressure target value 30 detected according to the invention is important for the invention relating to the operation of the engine in the gaseous fuel operating mode, which gas pressure target value comprises the pre-control component 36, the closed-loop control component 37 and the pressure difference. It depends on the target value 35.

  As described above, the gas pressure closed loop control 34 forms the difference between the gas pressure target value 30 and the gas pressure present value 31 at the subtraction point 56, and the gas pressure present value 31 and the gas pressure target value 30 are obtained. The difference between and is fed as an input variable to the second closed loop control circuit, ie the second controller 57 of the gas pressure closed loop control 34. The output variable 58 of this second control device 57 is corrected at least by the gas pressure target value 30, whereby the control variable 32 for the gas pressure control path 33 is supplied.

  The second controller 57 is preferably an I controller, which has exclusively an integral component.

  Upon detection of the gas pressure target value 30, the boost pressure present value 29 and the boost pressure target value 28 are filtered by the corresponding filters 59, 60, whereby the quality in determining the gas pressure target value 30 is determined. Will be improved. Similarly, the present gas pressure value 31 is also preferably filtered by the filter 61.

  According to an advantageous further development of the invention, the pressure difference setpoint 35 used for determining the gas pressure setpoint 30 is a pressure difference setpoint determined dependent on the quality of the gas or gas fuel GK. Is specified.

  For this purpose, in the pressure difference target value generation block 61 of FIG. 3, first, the pressure difference target value 62 independent of the gas quality is determined, and the pressure difference target value 62 independent of the gas quality is corrected. In which it is modified subject to a factor 64 relating to gas quality. The correction block 63 outputs, as an output variable, the pressure difference target value 35 depending on the gas quality.

  Therefore, the gas pressure target value 30 used in the gaseous fuel operation mode of the dual fuel engine or the gas engine depends on at least three variables. That is, the boost pressure present value 29, the boost pressure target value 28, and the pressure difference target value 35 are preferable, and the pressure difference target value 35 is preferably the pressure difference target value depending on the gas quality. Depending on the boost pressure present value 29 and the boost pressure target value 28, a pre-control component 36 and a closed-loop control component 37 are calculated for the gas pressure target value 30, for which at least, preferably gas quality The pressure difference setpoint value 35, which is dependent on, is superimposed, so that the gas pressure setpoint value 30 for the gas pressure closed loop control 34 is provided. The first control device 47 of the first closed-loop control circuit tracks the gas pressure target value 30 up to a deviation from the boost pressure target value 28. At this time, the preliminary control component 36 reduces the load on the closed loop control component 37, so that the high-quality gas pressure target value 30 can be quickly supplied. The gas pressure target value 30 is used in the second controller 57 of the second closed loop control circuit of the gas pressure closed loop control 34. That is, on the one hand, in order to detect the control deviation for the gas pressure closed loop control on the upstream side of the second control device 57, and on the downstream side of the second control device 57, the control variable 32 relating to the gas pressure control path 33. Used in determining.

  The boost pressure target value 38 is used as a basis for the preliminary control component 36 of the gas pressure target value 30. When added to the pressure difference target value 35, a preliminary control value for the gas pressure target value 30 results. In the case of stable behavior, the preliminary control value corresponds to the actually required gas pressure target value in the steady operation mode. In order to take into account the delay in the reaction behavior of the supercharged air closed loop control during load changes, the pre-controlled gas pressure target value 30 is approached through the pre-control ramp 44, but the gradient of the pre-control ramp is approached. Depends on a first temporal derivation of the current boost pressure 29. Therefore, the temporal behavior of the supercharging pressure is transmitted to the gas pressure target value 30, which leads to a stable pressure behavior. To compensate for the reaction delay of the gas pressure closed loop control 34, the actual pre-control component 36 is overlaid with a first temporal derivation of the pre-control component 36 at the summing point 39.

  A first controller 47 of the first closed-loop control circuit, which is used to determine the closed-loop control component 37 for the gas pressure setpoint 30, produces the preliminary control component 36 as a result of the temporal behavior of the boost pressure closed-loop control. Correct by the amount of control deviation in boost pressure. By combining the relatively fast pre-control component 36 and the precise closed-loop control component 37, a clearly improved time behavior is obtained for closed-loop controlled gas pressure and between supercharging pressure and gas pressure. Obtained with respect to the resulting pressure difference. As already explained, the control device 47 is offloaded by the preliminary control component 36. This is because, in the steady operation mode, the integral component of the controller 47 is completely absorbed by the preliminary control component 36, which allows the closed-loop control enhancement to be optimized.

  As mentioned above, the pressure difference setpoint 35 is preferably a pressure difference setpoint dependent on the quality of the gas. A further configuration of the invention is that the energization time of the gas valve increases, for example when the heating value of the gas decreases, at constant power and at a constant pressure difference between the gas pressure and the supercharging pressure. It is based on recognition. The significant fluctuations in the quality of the gas make it impossible to match the pressure difference to the specific heating value of the gas. In order to avoid unacceptably high injection angles of gas at low heating values, it is advantageous to use a pressure difference target value 35 which is dependent on the gas quality.

  Starting from a gas-pressure-independent pressure difference setpoint 62, which is optimized for efficiency, a gas-quality-dependent pressure-difference setpoint 35 is determined in dependence on a gas-quality factor 64.

  As a measure of the current heating value of the gas, a correction factor for controlling the quality of the gas, which is known per se, is preferably used. At that time, the correction coefficient increases as the calorific value of the gas decreases. The correction coefficient corrects the internal output or the filling calculation to the external output.

  If the correction factor reaches a value at which the injection time of the gas approaches the limit value, the pressure difference target value is increased. This function should be parameterized such that the gas injection time remains constant or decreases slightly. The correction factor for the quality of the gas is then preferably limited by both the minimum and maximum values. This is visualized in FIG. 4, in which the correction factor K2 for the pressure difference target value is entered above the correction factor K1 for the gas quality. The correction factor K1 for the quality of the gas is limited by a minimum value K1-min and a maximum value K1-max. A correction coefficient K2 for the pressure difference target value is assigned to each correction coefficient K1 for the gas quality. The pressure difference target value is limited by the maximum value K3.

  As already explained, the control variable 32 of the gas pressure closed loop control 34 depends on both the output variable 58 of the second control device 57 and the gas pressure target value 30. The output variable 58 of the control device 57 at the addition point 65 is corrected by the gas pressure target value 30. The output variable 58 of the control device 57 is dependent on the control deviation formed at the subtraction point 56 between the current gas pressure value 31 and the desired gas pressure value 30.

  The elements of the gas pressure control path 33 correspond to the prior art. Therefore, the gas pressure control path 33 includes the gas pressure control valve 66, and the gas pressure control valve is operated by the pilot control device 67. The input signal for the pilot controller 67 depends on the output signal of the so-called I / p converter 68 and the offset value 69. The I / p converter 68 produces a current signal for the pilot controller 67 from the control signal 32 of the gas closed loop control 34. The pilot controller 67 and the I / p converter 68 preferably operate on the same principle and provide an auxiliary energy source for the gas pressure control valve 66. The offset value 69 corresponds to the primary pressure for pretensioning the spring of the gas pressure control valve 66 to be actuated, which is adjusted via the adjusting screw.

  When the I / p converter 68, the pilot control device 67, and the pressure control valve 66 are operating normally, the gas pressure present value 31 in a stable state corresponds to the gas pressure target value 30. In order to compensate for adjustment errors, drifts and wear, a precise control of the gas pressure and thus of the pressure difference requires a control circuit which additionally comprises a second control device 57, which is however required. , As shown, can be configured as a pure I controller. This is because the interference variable changes only gradually. The deficiencies in the time behavior of the I / p converter 68, the pilot controller 67 and the pressure control valve 66 can be fully compensated by this.

  For the most efficient control in the gas pressure closed loop control 34, the exact offset value 69, which is typically adjusted by the adjusting screw in the pilot controller, must be known. Alternatively, a configuration is conceivable in which the parameterization of the offset value 69 is omitted and instead the output of the control device 67 is adaptively stored. Thereby, automatically all sources of error will be detected as compensation-offsets.

10 dual fuel engine 11 cylinder 12 exhaust gas turbocharger 13 turbine 14 compressor 15 piston 16 connecting rod 17 intake valve 18 exhaust valve 19 fuel injector 20 fuel pump 21 ignition fluid injector 22 ignition fluid storage device 23 ignition fluid pump 24 combustion chamber 25 Connection conduit 26 Combustion chamber 27 Closed loop control system 28 Supercharging pressure target value 29 Supercharging pressure current value 30, 30 'Gas pressure target value 30 Supercharging pressure target value 31 Gas pressure current value 32 Control variable 33 Gas pressure control path 34 Gas Pressure closed loop control 35 Pressure difference target value 36 Preliminary control component 37 Closed loop control component 38 Supercharging pressure target value 38 Differentiator 39 First addition point 39 Supercharging pressure current value 40 Auxiliary variable 40 Gas pressure target value 41 Second addition Point 42 Differentiator 43 Gradient 44 Preliminary control ramp 45 Minimum value 45 Minimum gradient 46 Difference 47 First controller 48 Proportional component 49 Integral component 50 Addition point 51, 54, 55 Block 52 Operating state 53 Leak test function 56 Subtraction point 57 Second control device 58 Output variable 59, 60, 61 Filter 61 Pressure difference target value generation block 62 Pressure difference target value 63 Correction block 64 Gas quality coefficient 65 Summing point 66 Gas pressure control valve 67 Pilot control device 68 I / P converter 69 offset value AG exhaust gas FK liquid fuel GK gas fuel K1 correction coefficient K1-max maximum value K1-min minimum value K2 correction coefficient K3 maximum value LL supercharged air ZF ignition fluid

Claims (9)

A method for operating an engine when gaseous fuel burns, comprising:
A gas / air mixture is formed from supercharged air supplied at a closed-loop controlled supercharging pressure and gas supplied at a closed-loop controlled gas pressure to burn the gaseous fuel. An air / air mixture is supplied to the cylinders of the engine for combustion,
Depending on the boost pressure target value (28) of the boost pressure closed loop control and the pressure difference target value (35) between the boost pressure and the gas pressure, the gas pressure for the gas pressure closed loop control is obtained. In the way the target value (30) is determined,
The gas pressure target value (30) is further determined depending on the boost pressure current value (29) of the boost pressure closed loop control, that is, the boost pressure current value (29) and the boost pressure target. A pre-control component (36) and a closed-loop control component (37) for the gas pressure target value (30) are determined depending on the value (30), the pre-control component (36) being an auxiliary variable. corrected by the adding the closed loop control component (37) to determine (40), the auxiliary variable (40), in order to determine the gas pressure target value (30), said pressure difference target value Corrected by adding (35) ,
The preliminary control component (36) is dependent on the temporal derivation of the current boost pressure (29) to determine the slope of the preliminary control ramp (44), and the boost pressure target value (28). ) Is determined so that the end point of the pre-control ramp (44) is determined . The closed loop control component (37) is used to determine the boost pressure present value (29) to determine the input variable for the first controller (47) of the first closed loop control circuit. ) And the closed loop control component (37) to be corrected, wherein the output variable of the first control device (47) corresponds to the closed loop control component (37). A method according to claim 1 . Method according to claim 2 , characterized in that the first controller (47) is a PI controller. The gas pressure target value (30), in order to determine the second input variable to a control system (57) of the second closed-loop control circuit, is corrected by the gas pressure present value (31), the second The output variable (58) of the controller (57) is corrected with the gas pressure target value (30) to determine the control variable (32) for the gas pressure control path (33) of the gas pressure closed loop control. Method according to any one of claims 1 to 3 , characterized in that Method according to claim 4 , characterized in that the second controller (57) is an I controller. Method according to any one of claims 1 to 5 , characterized in that the pressure difference setpoint (35) is determined as a function of the quality of the gas. During combustion of the gaseous fuel, a closed loop control system for operating the engine in a closed loop control system having a supercharging pressure closed-loop control and gas pressure closed-loop control,
A gas / air mixture is formed from supercharged air supplied at a closed-loop controlled supercharging pressure and gas supplied at a closed-loop controlled gas pressure to burn the gaseous fuel. An air / air mixture is supplied to the cylinders of the engine for combustion,
Generation of gas pressure target value is dependent on boost pressure actual value (29) and the supercharging pressure target value (28), preliminary control component for gas pressure target value (30) (36) and closed-loop control determine the component (37), generation of the gas pressure target value, the pre-control component (36) and the closed-loop control component (37), in order to determine the gas pressure target value (30), the over corrected by Kyu圧the pressure difference target value between the gas pressure (35),
The preliminary control component (36) of the generation of the gas pressure setpoint value is dependent on the temporal derivation of the current boost pressure value (29) to determine the slope of the preliminary control ramp (44), and Determining an end point of the preliminary control ramp (44) depending on the boost pressure target value (28); and
The closed loop control component (37) of the generation of the gas pressure setpoint is adapted to control the boost pressure present value (29) as a first, preferably PI, controller of a first closed loop control circuit. In order to determine an input variable for (47), the pre-control component (36) and the closed-loop control component (37) are corrected, the output variable of the first controller (47) being the closed-loop. Closed-loop control system, characterized in that it corresponds to the control component (37) . The gas pressure closed loop control determines the gas pressure target value (30) as an input variable for a control device (57) configured as a second, preferably I control device of a second closed loop control circuit. , corrected by the gas pressure present value (31), in which, the gas pressure closed loop control, the output variable of the second of said control device (57) to (58), the gas pressure closed-loop control of the gas pressure control path ( Closed loop control system according to claim 7 , characterized in that it is corrected with said gas pressure setpoint (30) to determine a control variable (32) for 33). Closed-loop control system according to claim 7 or 8 , characterized in that the pressure difference setpoint (35) is determined depending on the quality of the gas.

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