Control system for a turbocharger driven based on a compressor map

Abstract

A method for controlling a variable supercharger (501) for an engine system (500), comprising: Pressurizing an intake air (510) by a compressor (508) of the variable supercharger (501), Driving the variable supercharger (501) with a gearbox (522), Receiving, at a control unit (530), a desired first condition for the intake air (510) from the engine system (500), Calculating, at the control unit (530), a second state of the intake air (510) from the operating speed of the engine system (500) and from operating conditions of the engine system (500) corresponding to the desired first state, Determining a desired compressor speed (536) corresponding to the desired first state and the second state of the intake air (510) from a compressor map (540), Switching the transmission (522) to drive the compressor (508) to the desired compressor speed (536) to provide the desired first intake air condition (510) to the engine system (500), wherein the first state of the intake air (510) is a boost pressure (132) of the intake air (510) and the second state of the intake air (510) is a mass flow rate of the intake air (510).

Description

BACKGROUND OF THE INVENTION

[0001] Driven turbochargers offer an alternative to superchargers and turbochargers. Driven turbochargers can reduce turbo lag by allowing the engine system to drive the compressor when there is insufficient exhaust gases to drive the turbine. This is accomplished either through a mechanical connection via a gear box from the crankshaft or an electric motor connected to the engine's electrical system, which in turn transfers power to or from the turboshaft. Driven turbochargers can provide turbo compounding when excess exhaust energy is available to drive the turbine during high engine load conditions.JP - 2007 321 684 A describes a control device which is used for an internal combustion engine in order to switch between a first and a second operating system, wherein the control circuit selects the operating system based on the operating state-dependent output shaft torque and controls an electric compressor in accordance with the selected operating system, wherein the control device estimates the loss torque based on the determined load of a generator, determines the target torque by adding the estimated loss torque to the determined target torque and determines various control variables in order to exert a force on a piston which corresponds to the target torque and is determined by the combustion of the air-fuel mixture.JP 2001 - 227 351 A describes that a target intake amount corresponding to the required engine torque is calculated based on an engine operating condition signal including the accelerator pedal control input and the engine speed, a throttle valve is controlled to the target throttle opening calculated based on the target intake amount, the pressure ratio of the supercharger is calculated based on the target intake air amount, and the pressure ratio is controlled by the speed control of the supercharger or the bypass amount control of the discharged air of the supercharger to obtain the target pressure ratio.EP 2 799 691 A1 describes an electric supercharging device comprising an electric motor, a compressor which supercharges the intake air of a vehicle engine, a hydraulic accelerator which accelerates the rotation of the electric motor and transmits it to the compressor, and a speed adjusting device which controls the speed of the electric motor and an acceleration ratio of the hydraulic accelerator and adjusts the speed of the compressor, the hydraulic accelerator comprising a variable displacement hydraulic pump connected to and driven by the electric motor, a variable displacement hydraulic motor connected to the compressor and driven by the hydraulic pump with hydraulic oil, and a hydraulic circuit formed by the connection between the hydraulic pump and the hydraulic motor.WO 2015 / 079 061 A1 describes a supercharging arrangement having a compressor with a rotary drive, wherein a gearbox with a rotary drive receives the drive from an internal combustion engine and transmits the drive to a rotary drive output connected to the compressor input, the gearbox comprising a continuously variable transmission, for example a toroidal variator, operatively connected between the input and the output of the gearbox, wherein the compressor consists of a first and a second compressor connected in series within an air duct.JP 2007 - 132 298 A describes a turbocharger with a variable nozzle arrangement mounted on a diesel engine, wherein a motor assists the turbo rotation, the ECU controls the variable nozzle arrangement and the motor to bring the actual boost pressure detected by the boost pressure sensor into line with the target boost pressure, wherein in the boost pressure control with the assistance of the engine, the opening of the variable nozzle is fixedly controlled according to a predetermined map without any feedback due to the boost pressure difference to the opening of the variable nozzle. SUMMARY OF THE INVENTION

[0002] The present invention provides a method of controlling a variable supercharger for an engine system according to claim 1 and an engine system according to claim 16. Preferred embodiments are subject to the dependent claims. An embodiment of the invention may therefore provide a method of controlling a driven turbocharger for an engine system, comprising: pressurizing intake air by a compressor of the driven turbocharger; extracting energy, by a turbine of the driven turbocharger, from exhaust gases of the engine system; mechanically coupling, via a gearbox, the driven turbocharger to the engine system; receiving, at a control unit, a desired boost pressure for the intake air from the engine system; calculating, at the control unit, a mass flow rate of the intake air from the operating speed of the engine system and from operating conditions of the engine system corresponding to the desired boost pressure;Determining a desired compressor speed corresponding to the desired boost pressure and intake air mass flow rate from a compressor map; and shifting the transmission to a gear ratio that drives the compressor at the desired compressor speed to provide the desired intake air boost pressure to the engine system.

[0003] An embodiment of the invention may further provide a method for controlling a driven turbocharger for an engine system, comprising: pressurizing intake air by a compressor of the driven turbocharger; extracting energy, by a turbine of the driven turbocharger, from exhaust gases of the engine system; mechanically coupling, via a transmission, the driven turbocharger to the engine system; receiving, at a controller, a desired mass flow rate for the intake air from the engine system; calculating, at the controller, a boost pressure of the intake air from the operating speed and conditions of the engine system corresponding to the desired mass flow rate; determining, from a compressor map, a desired compressor speed corresponding to the desired mass flow rate and the boost pressure of the intake air;and shifting the transmission to a gear ratio that drives the compressor to the desired compressor speed to provide the desired mass flow rate of intake air to the engine system;

[0004] An embodiment of the invention may further provide an engine system comprising: a variable supercharger; a compressor of the variable supercharger that pressurizes intake air for the engine system; an electronic control unit that generates a desired first state of the intake air, calculates a corresponding second state of the intake air, wherein the second state depends on operating conditions of an internal combustion engine of the engine system, and uses a compressor map for the compressor to determine a desired compressor speed, wherein the desired compressor speed corresponds to the first state and the second state of the intake air; a transmission coupling the internal combustion engine to the compressor, wherein the transmission receives a control signal from the electronic control unit and shifts to a gear ratio that drives the compressor to the desired compressor speed.

[0005] An embodiment of the invention may further provide a method for controlling an electric supercharger for an engine system, the engine system comprising an internal combustion engine, a compressor that supplies compressed intake air to an intake port of the engine, and an electric motor coupled to the compressor and to power electronics of the engine system, the method comprising: receiving a desired boost pressure for the intake air from the engine system, calculating a mass flow rate of the intake air from the operating speed of the internal combustion engine and operating conditions of the internal combustion engine corresponding to the desired boost pressure; determining a desired compressor speed corresponding to the desired boost pressure and the mass flow rate of the intake air from a compressor map;and driving the electric motor with the power electronics to a rotational speed that rotates the compressor at the desired compressor speed.;

[0006] An embodiment of the invention may further provide a method for controlling an electric supercharger for an engine system, the engine system comprising an internal combustion engine, a compressor that supplies compressed intake air to an intake port of the engine, and an electric motor coupled to the compressor and to power electronics of the engine system, the method comprising: receiving a desired mass air flow for the intake air from the engine system; calculating a boost pressure of the intake air from the operating speed of the internal combustion engine and from internal combustion engine conditions corresponding to the desired mass flow rate; determining a desired compressor speed corresponding to the desired mass flow rate and the boost pressure of the intake air from a compressor map;and driving the electric motor with the power electronics to a rotational speed that rotates the compressor at the desired compressor speed.;

[0007] An embodiment of the invention may further provide an engine system comprising: an internal combustion engine; an electric supercharger; a compressor of the electric supercharger that compresses intake air for the engine system; an electronic control unit that generates a desired first state of the intake air, calculates a corresponding second state of the intake air, wherein the second state depends on operating conditions of the internal combustion engine, and uses a compressor map for the compressor to determine a desired compressor speed, wherein the desired compressor speed corresponds to the first state and the second state of the intake air; an electric motor that couples the compressor to power electronics of the engine system, receives a control signal from the electronic control unit, and rotates at a rotational speed that drives the compressor to the desired compressor speed. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic view of an engine system with a driven turbocharger. Fig. 2A is a compressor map for a centrifugal compressor. Fig. 2B is a compressor map that has undergone a coordinate transformation. Fig. Figure 3 is a schematic view of a control system with a velocity line lookup and a control loop. Fig. Figure 4 is a schematic view of an engine system with an electrically driven turbocharger. Fig. Figure 5A is a schematic view of an engine system with a mechanical supercharger. Fig. Figure 5B is a schematic view of an engine system with an electric supercharger. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0008] Fig. 1 is a schematic view of an engine system 100 with a driven turbocharger 101. An internal combustion engine 102 includes an intake passage 104 that supplies charge air to the internal combustion engine 102 and an exhaust passage 106 that exhausts exhaust gases 114 from the internal combustion engine 102. A compressor 108 compresses intake air 110 supplied to the intake passage 104. A turbine 112 receives exhaust gases 114 from the exhaust passage 106 and extracts energy from the exhaust gases 114. In some internal combustion engine applications, an exhaust gas recirculation (EGR) passage 116 may be provided, allowing exhaust gas recirculation from the exhaust passage 106 to the intake passage 104. In such cases, an EGR valve 118 controls the amount of EGR flow through the EGR passage 116. A turboshaft 120 connects the compressor 108 to the turbine 112 and is mechanically coupled to a transmission 122.This mechanical coupling may take the form of a high-speed traction drive. A high-speed traction drive system is disclosed in U.S. Patent No. 8,561,403 B2, filed October 22, 2013, entitled "Super-Turbocharger Having a High-Speed ​​Traction Drive and a Continuously Variable Transmission." The transmission 122 is mechanically coupled to the internal combustion engine 102. The transmission 122 has a variable gear ratio such that by shifting the transmission 122, the rotational speed of the turboshaft 120 can be controlled with varying rotational speeds and operating conditions of the engine 102. The transmission 122 is preferably a mechanical continuously variable transmission (CVT) with a finely adjustable gear ratio. The transmission 122 may also be a discrete multi-speed transmission.The skilled person should be familiar with the operation of a mechanical CVT and a discrete multi-speed transmission.

[0009] The engine system 100 is electronically controlled by an electronic control unit 130. The electronic control unit 130 determines a desired boost pressure 132 for the intake port 104, which depends on engine speed and operating conditions. The electronic control unit 130 also receives a measured boost pressure 134 from the intake port 104. The electronic control unit 130 can use this measured boost pressure. Instead of relying solely on closed-loop control from a measured boost pressure 134, a faster and more stable control system can be provided by shifting the transmission 122 directly to a gear ratio providing the desired boost pressure 132.The electronic control unit 130 outputs the desired gear ratio to the transmission 122 based on calculations related to the measured boost pressure 134, the desired boost pressure 132, and a resulting desired compressor speed 136 from a compressor map 140. In particular, this is accomplished by calculating a mass flow rate of the intake air 110 corresponding to the desired boost pressure 132 and operating conditions of the engine 102.Once a boost pressure and mass flow rate for the intake air 110 have been determined for a particular operating condition, these parameters are used to determine a desired compressor speed 136 using the compressor map 140 for the compressor 108. In compressor maps, the mass flow rate of the intake air 110 is, by default, corrected based on conditions (pressure, temperature, and gas properties as described further below) of the intake air to the compressor 108, and a pressure ratio across the compressor 108 is determined from the boost pressure divided by the intake pressure. The compressor map 140 is used as a lookup table, with the corrected mass flow and pressure ratio being input, and the desired compressor speed 136 being output back to the electronic control unit 130.The compressor map 140 can be subjected to a coordinate rotation or transformation to simplify compressor speed lookup, as described below. The output compressor speed is the desired compressor speed 136 for the engine operating point. Because the speed (RPM) of the internal combustion engine 102 is known, a desired gear ratio 138 of the transmission 122 can be calculated. Shifting the transmission 122 to this desired gear ratio then drives the compressor 108 to the desired compressor speed 136.

[0010] An example of calculating the mass flow rate of intake air 110 using parameters and operating conditions of the internal combustion engine 102 is as follows: M˙air=[EngineRPM120,000∗EngineDisp∗ηvEGRfrac1−EGRfrac∗TEGR+Tair]∗PboostR where: Ṁ air the mass flow rate of the inlet air 110 is Engine RPM the speed (rpm) of the engine 102 is Engine Disp the displacement of the engine 102 in liters is n v the volumetric efficiency of the engine 102 is EGR frac the EGR portion of the intake air to the engine 102 is T EGR the temperature of the EGR flow in Kelvin is T air is the temperature of the air flow in Kelvin P boost the desired boost pressure is 132 in Pascal absolute R is the gas constant in J / kgK

[0011] A simplification of the above equation can be obtained because the mass flow rate of the intake air 110 is proportional to the boost pressure of the intake air 110. Therefore, assuming that engine operating conditions do not change significantly between similar operating points, a measured air mass flow rate can be used along with the desired boost pressure 132 and the measured boost pressure 134 of the intake air 110. The simplified equation is as follows: M˙air=M˙airmeasured∗PboostdesiredPboostmeasured

[0012] When the electronic control unit 130 maintains the operating conditions of the engine 102 close to the desired operating conditions of the engine 102, this simplified equation provides an estimate of a desired mass flow rate of the intake air 110 for a given desired boost pressure 132. An alternative is to use a lookup table based on engine operating conditions to obtain a mass flow rate of the intake air 110.

[0013] The above equations are based on the electronic control unit 130 generating a desired boost pressure 132 and calculating a corresponding intake air mass flow rate 110. The electronic control unit 130 can also be operated by determining a desired intake air mass flow rate 110 based on engine operating conditions and calculating a corresponding intake air boost pressure 110. The above equations can be rearranged to generate a calculated intake air boost pressure 110 from a desired intake air mass flow rate 138: Pboost=[EGRfrac1−EGRfrac∗TEGR∗TairEngineRPM120,000∗EngineDisp∗ηv]∗M˙air∗R Pboost=Pboostmeasured∗M˙airdesiredM˙airmeasured

[0014] As previously mentioned, the calculated intake air boost pressure 110 can also be determined from a lookup table based on engine operating conditions. Again, the end result is a mass flow rate and intake air boost pressure 110 for input to a compressor map for compressor 108.

[0015] Fig. 2A shows a compressor map 200 for a centrifugal compressor such as the compressor 108 of Fig. 1. The x-axis shows the corrected air mass flow rate 202, and the y-axis shows the pressure ratio 204. The compressor speed lines 206 show where in the map the compressor is operating for a given compressor speed. The values ​​of the boost pressure and the intake air mass flow rates from Fig. 1 corresponding to the desired engine operating condition are used to determine the corrected air mass flow rate value 208 and the pressure ratio value 210 for input to the compressor map 200 to determine a desired compressor speed 212. The pressure ratio value 210 is calculated by dividing the desired boost pressure by the compressor inlet pressure. The corrected air mass flow rate value 208 is determined by the following standard equation: M˙cor=M˙act∗[PrefPinlet]∗γrefγinletRinletRrefTinletTref

[0016] Assuming that the gas properties of the inlet air 110 always correspond to the reference values, the corrected mass flow rate of the air calculation can be simplified to: M˙cor=M˙act∗[PrefPinlet]∗TinletTref

[0017] Once the corrected air mass flow rate value 208 and the pressure ratio value 210 have been determined, various interpolation methods between the given velocity lines 206 can be used to determine the desired compressor speed 212. Those skilled in the art should be familiar with the various interpolation methods for determining a desired compressor speed 212. For example, linear interpolation or wedge interpolation can be used.

[0018] Fig. Figure 2B shows a compressor map 200 that has undergone a coordinate transformation to provide a coordinate-transformed compressor map 201 for simplifying the lookup of the desired compressor speed 212. The compressor speed lines include the values ​​for the corrected air mass flow rate 202 and the pressure ratio 204, which have been converted to a new x-coordinate 214 and a new y-coordinate 216, respectively. The conversion is accomplished by a standard rotation and a translation calculation of: X'=R[X−O] where: X' is the new x-coordinate and the new y-coordinate is X is the corrected mass flow rate of air and the pressure ratio is O are the origin coordinates for the transformation R is the rotation matrix for the transformation in the form of [cosθ-sinθsinθcosθ] where θ is the angle of rotation of the transformation.

[0019] The corrected mass flow rate value 208 of the air (see Fig. 2A) and the pressure ratio value 210 (see Fig. 2A) are also subjected to this coordinate transformation in order to be used in the new lookup table, namely the coordinate-transformed compressor map 201. In the exemplary compressor map 200 of Fig. 2A, the original coordinates are [0.0280721; 1.08773] and the rotation matrix is ​​[cos(3.86°) -sin(3.86°); sin(3.86°) cos(3.86°)]. Applying this to the exemplary corrected mass flow rate value 208 of air of 0.21 kg / s and the pressure ratio value 210 of 2.25 of Fig. 2A results in transformed coordinate values ​​218 of [0,103; 1,17], which are input as lookup values ​​into the coordinate-transformed compressor map 201 to determine a desired compressor speed 212.

[0020] Fig. Figure 3 is a schematic view of a control system 300 with a velocity line lookup and a control loop. Inputs to the system are the desired mass flow 302, the desired pressure ratio 304 (as described with reference to Fig. 2A) as well as the ambient pressure 306 and the ambient temperature 308. The desired mass flow 302 is corrected in accordance with the above formula using the ambient pressure 306 and the ambient temperature 308. The correction results in a corrected mass flow 310 for the compressor map lookup along with the desired pressure ratio 304. These two values ​​are compressor map lookup values ​​312 for the lookup table in Fig. 2A. To simplify the compressor map lookup table, the compressor map lookup values ​​312 are subjected to the same coordinate transformation as the compressor map as with respect to Fig. 2B. This coordinate transformation involves subtracting the rotated frame origin 314 from the compressor map lookup values ​​312 and multiplying the result by a rotation matrix 316 as described above with reference to Fig. 2B to generate transformed compressor map lookup values ​​318. These transformed compressor map lookup values ​​318 are input into the lookup table 320 corresponding to the transformed compressor map of Fig. 2B. The output of this lookup table 320 is a desired compressor speed 322, which is then converted to a corresponding lookup table gear ratio 330. This conversion includes multiplying the desired compressor speed 322 by a gain 324 based on the design of the driven turbocharger to obtain a transmission output speed 326, and dividing this transmission output speed by a transmission input speed 328. In a simplified embodiment without a closed-loop control, this lookup table gear ratio 330 includes the commanded gear ratio 322, which is then input to the transmission 122 in Fig. 1 is entered. In the embodiment of Fig. 3, an additional correction is made to the gear ratio via a feedback loop 334. The feedback loop 334 subtracts a measured control variable 336 from a desired control variable 338 to generate a control variable error 340. The measured control variable 336 and the desired control variable 338 may be intake air boost pressures, intake air mass flows, or other engine system variables. The control variable error 340 is input to a controller 342, which generates a ratio correction 344. The controller 342 may be a PID (proportional-integral-derivative) control strategy or another control strategy. Control strategies are known to those skilled in the art. A ratio correction 344 is then added to the lookup table gear ratio 330 to generate a commanded gear ratio 332.

[0021] Fig. Figure 4 is a schematic view of an engine system 400 with an electrically driven turbocharger 401. The function is similar to that shown in Fig. 1, but the turbocharger is electrically driven rather than mechanically driven. The operation of mechanically driven turbochargers and electrically driven turbochargers is known to those skilled in the art. The internal combustion engine 402 includes an intake passage 404 that supplies charge air to the engine 402 and an exhaust passage 406 that expels exhaust gases 414 from the internal combustion engine 402. The compressor 408 compresses intake air 410 that is supplied to the intake passage 404. The turbine 412 receives exhaust gases 414 from the exhaust passage 406 and extracts energy from the exhaust gases 414. In some internal combustion engine applications, an exhaust gas recirculation (EGR) passage 416 may be provided, allowing exhaust gas recirculation from the exhaust passage 406 to the intake passage 404. In such cases, an EGR valve 418 controls the amount of EGR flow through the EGR passage 416.A turboshaft 420 connects the compressor 408 to the turbine 412 and is mechanically coupled to an electric motor / generator 422. This mechanical coupling may take the form of a high-speed traction drive as described above with reference to FIG. Fig. 1 or may be a direct connection. The electric motor / generator 422 is electrically coupled to power electronics 424 of the motor system 400. The power electronics 424 enables current flow between the electric motor / generator 422 and the motor system 400. The current flow may control the rotational speed of the motor / generator 422.

[0022] The engine system 400 is electronically controlled by an electronic control unit 430. In the same way as in Fig. 1, the electronic control unit 430 determines a boost pressure and a mass flow rate 432 for an intake air 410, which are dependent on the engine speed and operating conditions such as engine load. These values ​​are then input into a compressor map 440 for a compressor 408 to generate a desired compressor speed 436. The electronic control unit 430 outputs a control signal 442 to the power electronics 424, which then supplies the electric motor / generator 422 with power for a rotational speed at which the turboshaft 420, and thus the compressor 408, is driven to a desired compressor speed 436.

[0023] Fig. 5A is a schematic view of an engine system 500 with a variable supercharger 501. An internal combustion engine 502 includes an intake passage 504 that supplies charge air to the internal combustion engine 502 and an exhaust passage 506 that exhausts exhaust gases 514 from the internal combustion engine 502. A compressor 508 compresses intake air 510 that is supplied to the intake passage 504. A compressor shaft 520 is connected to the compressor 508 and mechanically coupled to a transmission 522. The mechanical coupling may take the form of a high-speed traction drive as described above with reference to Fig. 1. The transmission 522 is mechanically coupled to the internal combustion engine 502 and has a variable gear ratio so that shifting the transmission 522 can control the rotational speed of the turboshaft 520 with varying rotational speeds and operating conditions of the internal combustion engine 502. The engine system 500 is electronically controlled by an electronic control unit 530. The electronic control unit 530 determines a desired boost pressure 532 for the intake port 504, which is dependent on the engine speed and operating conditions. A corresponding mass flow rate of the intake air 510 to the desired boost pressure 532 is calculated based on operating conditions of the internal combustion engine 502. The boost pressure and the mass flow rate for the intake air 510 are input into a compressor map 540 for the compressor 508 to determine a desired compressor speed 536 for the operating point.A measured boost pressure 534 can also be used for an additional control loop to fine-tune the desired compressor speed 536. The electronic control unit outputs a desired gear ratio signal 538 to the transmission 522, which shifts the transmission 522 to drive the compressor 508 at the desired compressor speed 536.

[0024] Fig. 5B is a schematic view of the engine system 500 of Fig. 5A, which however has an electrically variable supercharger 501. The overall operation follows the description of Fig. 5A, except that the turboshaft 520 is coupled to an electric motor 550, which in turn is electrically coupled to the engine system 550 via power electronics 552. The desired compressor speed 536 is determined from the compressor map 540 by an electronic control unit 530 in the same manner as in Fig.5A, the electronic control unit 530 outputs a control signal 554 to the power electronics 552, which then supplies power to the electric motor 550 to drive the compressor 508 to the desired compressor speed 536.

Claims

[1] A method for controlling a variable supercharger (501) for an engine system (500), comprising: Pressurizing an intake air (510) by a compressor (508) of the variable supercharger (501), Driving the variable supercharger (501) with a gearbox (522), Receiving, at a control unit (530), a desired first condition for the intake air (510) from the engine system (500), Calculating, at the control unit (530), a second state of the intake air (510) from the operating speed of the engine system (500) and from operating conditions of the engine system (500) corresponding to the desired first state, Determining a desired compressor speed (536) corresponding to the desired first state and the second state of the intake air (510) from a compressor map (540), Switching the transmission (522) to drive the compressor (508) to the desired compressor speed (536) to provide the desired first intake air condition (510) to the engine system (500), wherein the first state of the intake air (510) is a boost pressure (132) of the intake air (510) and the second state of the intake air (510) is a mass flow rate of the intake air (510). [2] The method of claim 1, further comprising: Coupling a turbine (112) that extracts energy from exhaust gases of the engine system (500) to the compressor (508) to form a driven turbocharger (101). [3] The method of claim 1, wherein the transmission comprises an electric motor (550) coupled to power electronics (552) of the engine system (500) to form an electrically variable supercharger (501). [4] The method of claim 3, further comprising: a reduction gear between the compressor (508) and the electric motor (550) so that the electric motor (550) rotates at a reduced speed. [5] The method of claim 4, wherein the reduction gear comprises a traction drive. [6] The method of claim 1, further comprising: Coupling a turbine (412) to the compressor (508) that extracts energy from exhaust gases of the engine system (500) to form an electrically driven turbocharger (401). [7] The method of claim 1, wherein the transmission (522) is a mechanically continuously variable transmission mechanically coupled to the compressor (508) and an internal combustion engine (502) of the engine system (500). [8] The method of claim 7, further comprising: a reduction gear between the compressor (508) and the mechanically continuously variable transmission so that the mechanically continuously variable transmission rotates at a reduced speed. [9] The method of claim 8, wherein the reduction gear comprises a traction drive. [10] The method of claim 1, further comprising: Obtaining a measured intake air boost pressure (510), Providing a control loop that compares the measured boost pressure (534) of the intake air (510) with the desired boost pressure (532) for the intake air and adjusts the gear ratio of the transmission to guide the measured boost pressure (534) of the intake air (510) to the desired boost pressure (532) for the intake air (510). [11] The method of claim 10, wherein the control loop comprises a PID (proportional-integral-derivative) control strategy. [12] The method of claim 1, wherein the method for calculating the mass flow rate of intake air (510) comprises using a plurality of variables in a calculation, the plurality of variables including engine displacement, engine speed, desired boost pressure (532), exhaust gas recirculation (EGR) fraction, and volumetric efficiency of the engine system (500). [13] The method of claim 1, wherein the method for calculating the intake air mass flow rate (510) comprises scaling a measured intake air mass flow rate (510) by the ratio of the desired boost pressure (532) divided by a measured boost pressure (534) of the intake air (510). [14] The method of claim 1, wherein the method for calculating the mass flow rate of intake air (510) comprises using a lookup table based on the operating speed and operating conditions of the engine system (500). [15] The method of claim 1, further comprising applying a transformation to the compressor map (540). [16] Engine system (500), comprising: a variable supercharger (501), a compressor (508) of the variable supercharger (501) which compresses an intake air (510) for the engine system (500), an electronic control unit (530) that generates a desired first state of the intake air (510), calculates a corresponding second state of the intake air (510), wherein the second state depends on operating conditions of an internal combustion engine (502) of the engine system (500), and uses a compressor map (540) for the compressor (508) to determine a desired compressor speed (536), wherein the desired compressor speed (536) corresponds to the first state and the second state of the intake air (510), a transmission (522) coupled to the compressor (508), the transmission (522) receiving a control signal from the electronic control unit (530) and being switched to drive the compressor (508) to the desired compressor speed (536), wherein the desired first state of the intake air (510) is a boost pressure (132) of the intake air (510) and the second state of the intake air (510) is a mass flow rate of the intake air (510). [17] The engine system (500) of claim 16, wherein the transmission (522) is a mechanically continuously variable transmission. [18] The engine system (500) of claim 16, wherein the engine system (500) further comprises: a turbine (112, 412) coupled to the compressor (508), which receives exhaust gases from the internal combustion engine (502) and generates energy from the exhaust gases. [19] The motor system (500) of claim 16, wherein the transmission (522) is an electric motor (550).

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