Transient compensation for variable geometry compressors

Abstract

This application relates to transient compensation for variable geometry compressors. Methods and systems for controlling a turbocharged engine are provided. In one example, a method includes adjusting exhaust gas recirculation gas flow and turbine flow while adjusting a geometry of a compressor to compensate for disturbances caused by the compressor adjustment.

Description

TECHNICAL FIELD

[0001] This specification generally relates to methods and systems for controlling operation of a variable geometry compressor coupled to an internal combustion engine. BACKGROUND

[0002] Engines can use turbochargers to provide boosted intake air for improved engine torque / power output density. A turbocharger can include a compressor coupled to an exhaust-driven turbine. Depending on operating conditions, the compressor can experience surge and / or choke. Surge can occur during low air mass flow when the air flow through the compressor stalls or reverses. For example, compressor surge can occur in response to a sharp throttle up or can occur at high exhaust gas recirculation (EGR) rates. Compressor surge can result in noise, vibration, and harshness (NVH) issues, such as undesirable noise from the engine intake system. Choke can occur when the air flow through the compressor cannot be increased for a given speed of the compressor. For example, compressor choke can occur in response to an aggressive throttle down from an idle engine speed condition. During choke, the turbocharger cannot provide additional air to the engine, so the engine power output density is temporarily limited.

[0003] Various methods have been developed to expand the compressor operating range. One example method includes boosting air with a variable geometry compressor (VGC), where the air flow through the compressor can be adjusted by changing the geometry or position of the VGC. As an example, the pattern of air flow into the compressor can be adjusted by adjusting the angle of the vanes. As another example, the air flow through the compressor can be modified with a passive casing treatment including fixed slots and / or ports. During low air mass flow conditions, the slots of the passive casing treatment can provide a path to partially recirculate pressurized air back to the compressor inlet. The recirculated air through the compressor can enable the compressor to operate at lower air mass flow rates before surge occurs. During high air mass flow conditions, the slots and / or ports of the passive casing treatment can provide a path for short-circuit air flow through the compressor, so that the compressor can operate at higher air mass flow rates before choke occurs. One drawback of the passive casing treatment system is that the effective position of the passive recirculation slots for preventing surge is different from the effective position of the passive recirculation slots for preventing choke.

[0004] Another example method includes using active casing treatment (ACT) for the compressor, such as shown in U.S. 8,517,664 (Sun et al.). Therein, the turbocharger includes an active casing treatment, an impeller, a casing, and a diffuser. A controller adjusts a casing sleeve in response to a mass flow condition relative to a threshold or based on a pressure differential in the engine system such that a slot in the casing sleeve is aligned with a surge slot or choke slot. In response to the slot alignment, air is selectively allowed to flow between the impeller and the compressor inlet.

[0005] In addition to the above problems, the inventors have also recognized that changes in the geometry or position of the compressor can temporarily disturb engine operating parameters from their desired set points. The transient disturbances can cause NVH and degrade engine performance. As an example, an engine operating parameter can be controlled by operating an actuator via a feedback control loop. The feedback control signal to the actuator can reflect a compressor adjustment only when an error in the engine operating parameter has occurred and has been sensed. In other words, the response time of the feedback control loop can be slow. On the other hand, the process of adjusting the compressor geometry or position can be fast relative to the response time of the feedback control loop. For example, the process of moving a casing sleeve of an ACT compressor to align with a surge slot or choke slot can be abrupt and / or discontinuous. Thus, the feedback controller can have a limited bandwidth to compensate for and reduce disturbances caused by compressor geometry adjustments, particularly when the controller is tuned to respond to a variety of other disturbances as well as disturbances that can be activated by the driver to provide certain driving experiences. As a result, vibrations and noise can occur in response to each compressor geometry adjustment, and torque disturbances can also occur. Engine fuel economy and emissions can likewise be affected. SUMMARY

[0006] In one example, the above problems can be addressed by a method that includes adjusting EGR flow via a first actuator and adjusting turbine flow via a second actuator while adjusting a geometry of a compressor, wherein the EGR flow and the turbine flow are adjusted based on the adjustment of the geometry of the compressor. In this way, disturbances in engine operating parameters in response to the compressor adjustment can be reduced and / or compensated for in a timely manner.

[0007] As another example, engine gas flow and pressure can be controlled by adjusting EGR flow and turbine flow via a feedback control loop during engine operation. In particular, EGR flow and turbine flow can be adjusted by actuating the first actuator and the second actuator, respectively, with control signals determined based on measured engine gas flow and pressure. In response to a compressor surge or choke, the geometry or position of the compressor can be adjusted via a compressor actuator to expand the compressor operating range. Upon actuation of the compressor actuator to a desired position, EGR flow and turbine flow can be simultaneously adjusted to counteract the disturbance caused by the compressor geometry adjustment. For example, the feedforward control signals to the first actuator and the second actuator can be subtracted from the feedback control signals while the compressor actuator is actuated. The feedforward control signals can be determined based on the expected disturbance to engine gas flow and pressure. In this way, engine gas flow and pressure can be transiently adjusted in response to the compressor geometry change. During the compressor adjustment, gas flow and pressure can be maintained substantially constant (e.g., within 5% of the average), reducing the deviation of engine operating parameters from desired set points. After the compressor is adjusted, engine gas flow and pressure can be controlled to desired levels by the feedback loop. By sending feedforward control signals to the first actuator and the second actuator while the compressor is actuated, the disturbance in engine gas flow and pressure can be reduced and the onset of the disturbance can be anticipated.

[0008] It should be appreciated that the above Overview is provided merely for purposes of summarizing some implementations of the concepts described in the detailed description. It is not meant to limit the claims of the patent in any manner. Furthermore, the claims are not limited to implementations that solve any or all of the disadvantages of any of the problems presented in the background section or any part of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 An example embodiment of a vehicle system including a turbocharged engine is shown.

[0010] Figure 2 An example embodiment of a turbocharger is shown. Figure 1 An example embodiment of a cylinder of a turbocharged engine is shown.

[0011] Figure 3 An example embodiment of a turbocharger is shown. Figure 1 An example embodiment of a turbocharger is shown. Figure 2 A cross-sectional view of an example embodiment of a turbocharger is shown.

[0012] Figure 4A A sleeve actuation to a surge position for active nacelle treatment is shown.

[0013] Figure 4B A sleeve actuation to a choke position for active nacelle treatment is shown.

[0014] Figure 5 A control block for a turbocharged engine is shown.

[0015] Figure 6 An example method for controlling a turbocharged engine is shown.

[0016] Figure 7 Changes in engine operating parameters and states of actuators over time while implementing the method of Figure 6 are shown.

[0017] Figure 8 An example compressor performance map is shown. DETAILED DESCRIPTION

[0018] The following description relates to systems and methods for controlling a turbocharged engine. An example vehicle system and an example cylinder within a vehicle system are shown in Figure 1 and Figure 2 respectively. In one example, as shown in Figure 3 , the vehicle system can include a compressor coupled with a turbine. In response to an indication of compressor surge or choke, the geometry or position of the compressor can be adjusted to expand the compressor operating range. Figure 4A to Figure 4B One example compressor, in which the compressor geometry can be adjusted by moving the active casing treatment, is known. Figure 5 An example control block for controlling engine operating parameters is shown. Engine operating parameters such as engine gas flow and pressure can be controlled via a feedback control loop. By introducing a feedforward control signal, disturbances caused by compressor adjustments can be compensated. Figure 6 An example method for controlling a turbocharged engine with a variable geometry compressor is shown in Figure 6 . In particular, in response to an anticipated compressor surge or choke, EGR flow and turbine flow are adjusted while actuating the compressor actuator to avoid disturbances in engine operating parameters. Figure 7 Changes in engine operating parameters and states of actuators over time while implementing the method of Figure 8 are shown.

[0019] Now turning to Figure 1FIG. 1 schematically depicts an example embodiment of a vehicle system 100. In one example, the vehicle system 100 can be configured as an on-road motor vehicle. However, it should be appreciated that in other examples, the vehicle system 100 can be configured as an off-road vehicle. In some examples, the vehicle system 100 can be a hybrid vehicle having multiple torque sources available for one or more wheels 76. In other examples, the vehicle system 100 is a conventional vehicle having only an engine, or an electric vehicle having only electric machine(s). In the depicted example, the vehicle system 100 includes an engine 10 and an electric machine 72. The electric machine 72 can be a motor or a motor / generator. When one or more clutches 73 are engaged, the crankshaft 40 of the engine 10 and the electric machine 72 are connected to the wheels 76 via a transmission 74. In the depicted example, a first clutch 73 is disposed between the crankshaft 40 and the electric machine 72, and a second clutch 73 is disposed between the electric machine 72 and the transmission 74. The controller 12 discussed herein can send signals to actuators of each clutch 73 to engage or disengage the clutch in order to connect or disconnect the crankshaft 40 from the electric machine 72 and components connected to the electric machine 72, and / or to connect or disconnect the electric machine 72 from the transmission 74 and components connected to the transmission 74. The transmission 74 can be a gearbox, planetary gear system, or other type of transmission. The powertrain can be configured in various ways, including as a parallel, series, or series-parallel hybrid vehicle.

[0020] The electric machine 72 receives electrical power from a traction battery 75 to provide torque to the wheels 76. The electric machine 72 can also operate as a generator to provide electrical power to charge the battery 75, for example, during braking operations. In other examples, where the vehicle system 100 is a conventional vehicle having only an engine, the traction battery 75 can be a starting-lighting-ignition (e.g., SLI) battery that supplies electrical energy to the vehicle system 100.

[0021] In the depicted embodiment, the engine 10 is a turbocharged engine including a turbocharger 13. The turbocharger 13 includes a turbine 116 positioned in an exhaust passage 35 that is coupled to a compressor 110 positioned in an intake passage 42. The turbine 116 and the compressor 110 can be coupled via a shaft 19. The compressor 110 can be positioned upstream of a charge air cooler 18 (also referred to herein as a CAC) and an intake throttle 20. The turbine 116 can be driven (e.g., spun) by expansion of exhaust gases from the engine 10, and rotational energy of the turbine 116 can be transferred via the shaft 19 to rotate the compressor 110.

[0022] The geometry of the compressor 110 can be adjusted by operating the compressor actuator 118. In one example, the compressor 110 is a variable geometry compressor (VGC) that has vanes that move according to a desired vane angle to direct intake airflow into the compressor in different modes. Further, as set forth with reference to Figure 3 and Figure 4A to Figure 4B The compressor 110 can include an active casing treatment (ACT) with a sleeve that can be actuated between different positions to reduce or increase the flow into the compressor wheel (or impeller) in response to an indication of surge (actual or predicted). For example, in response to an indication of surge (actual or predicted), the sleeve can be actuated by the engine controller to the surge slot to increase the flow from the compressor wheel to the compressor inlet. In another example, in response to an indication of choke (actual or predicted), the sleeve can be actuated by the engine controller to the choke slot to increase the flow from the compressor inlet into the compressor wheel.

[0023] In some examples, the turbine 116 can be a variable geometry turbine (VGT) with vanes that are adjustable to direct exhaust airflow through the turbine vanes in different modes, thereby varying the turbine speed and boost pressure provided by the turbocharger 13. The airflow through the turbine 116 can be adjusted via the actuator 117.

[0024] The engine 10 receives air along the intake passage 42 via an airbox 44 that includes an air cleaner 112. The air is compressed by the compressor 110 of the turbocharger 13, and the compressed air is delivered to the induction passage 43. The compressed air passes through the induction passage 43, is cooled by the CAC 18 and passes through the throttle valve 20 before entering the intake manifold 22, at which point the compressed air enters the engine 10. In other words, the compressor 110 is coupled to the intake throttle valve 20 by way of the charge air cooler 18, and the intake throttle valve 20 is coupled upstream of the intake manifold 22. The charge air cooler can be an air-to-air heat exchanger or a water-to-air heat exchanger, for example. In Figure 1 In the embodiment shown in FIG. 1, the pressure of the air charge within the intake manifold is sensed by a manifold air pressure (MAP) sensor 124.

[0025] It will be appreciated that other combinations and configurations of boost devices are possible. In one embodiment, the engine system 100 can include a supercharger, in which the compressor 110 can be at least partially driven by an electric motor and / or the engine 10, and the engine system can not include the turbine 116. In further examples, multiple boost devices can be staged in series, such as where both a supercharger and a turbocharger are coupled to the intake passage.

[0026] The compressor 110 can include a recirculation passage 80 across the compressor. The depicted example shows a compressor recirculation valve (CRV) 82 coupled across the recirculation passage 80, where actuation of the CRV 82 adjusts the flow through the recirculation passage 80. Warm compressed air from the compressor outlet can be recirculated back to the compressor inlet via the recirculation passage 80. In some embodiments, the compressor recirculation system can alternatively or additionally include a recirculation passage for recirculating (cooled) compressed air from the compressor outlet downstream of the charge air cooler to the compressor inlet or a compressor bypass for dissipating compressed air to the atmosphere (not shown). The CRV 82 can be a continuously variable valve, where the position of the valve is continuously variable from a fully closed position to a fully open position. In some embodiments, the partially open compressor recirculation valve 82 can be maintained during turbocharged engine operation to provide some surge margin. Herein, the partially open position can be the default valve position. Increasing the opening of the compressor recirculation valve can include actuating (or energizing) a solenoid of the valve. Further discussion of exemplary CRV operation will be explored herein.

[0027] One or more sensors can be coupled to the inlet of the compressor 110 for determining the composition and conditions of the charge air entering the compressor. For example, an intake air temperature (IAT) sensor 55 can be coupled to the intake passage 42 proximate the inlet of the compressor 110 for estimating the compressor inlet temperature. As another example, a pressure sensor 56 can be coupled to the inlet of the compressor for estimating the pressure of the charge air entering the compressor. In further examples, a mass air flow (MAF) sensor 57 can also be coupled to the inlet of the compressor for estimating the amount of air entering the engine. Other sensors can include, for example, an air-fuel ratio sensor, a humidity sensor, etc. In other examples, one or more of the compressor inlet conditions (such as humidity, temperature, etc.) can be inferred based on engine operating conditions. The sensors can estimate the conditions of the intake air received from the intake passage at the compressor inlet and the conditions of the charge air recirculated upstream from the CAC. A throttle inlet pressure (TIP) sensor 58 or other suitable sensor can be coupled downstream of the compressor 110 and upstream of the throttle 20 for measuring the turbocharged pressure at a location downstream of the compressor 110 and upstream of the throttle 20. In this way, the compressor outlet pressure can be determined. The compressor pressure ratio can be calculated by dividing the compressor outlet pressure by the compressor inlet pressure (such as the pressure measured by the sensor 56).

[0028] The intake manifold 22 is coupled to the series of combustion chambers 30 by a series of intake valves (referenced Figure 2 The intake manifold 22 is coupled to the series of combustion chambers 30 by a series of intake valves (referenced Figure 2(As described separately) The combustion chamber is additionally coupled to the exhaust manifold 36. In the depicted embodiment, a single exhaust manifold 36 is shown. However, in other embodiments, the exhaust manifold 36 may include multiple exhaust manifold sections. A configuration with multiple exhaust manifold sections allows effluent from different combustion chambers to be directed to different locations within the engine system 10. A sensor 125 may be coupled to the exhaust manifold for measuring exhaust flow.

[0029] Combustion chamber 30 can be supplied by the fuel system (reference) Figure 2 (As described elsewhere) One or more fuels, such as gasoline, alcohol-fuel mixtures, diesel, biodiesel, compressed natural gas, etc., are supplied. Fuel can be supplied to the combustion chamber via direct injection, port injection, throttle body injection, or any combination thereof. Direct injection involves injecting fuel directly into the combustion chamber, while port injection delivers a fuel spray into the intake manifold, where the fuel spray mixes with the intake air before entering the combustion chamber. This example may include a plurality of direct fuel injectors 66 and port fuel injectors 67. In the combustion chamber, combustion can be initiated via spark ignition and / or compression ignition.

[0030] like Figure 1 As shown, exhaust gas from one or more sections of exhaust manifold 36 is directed to turbine 116 to drive the turbine. When a reduction in turbine torque is desired, some exhaust gas may instead be directed through wastegate 90, bypassing turbine 116. Wastegate valve 92, coupled to wastegate 90, can be actuated to open to release at least some of the exhaust pressure upstream of turbine 116 to a location downstream of turbine via wastegate 90. By reducing the exhaust pressure upstream of turbine 116, turbine speed can be reduced. In one embodiment, wastegate valve 92 may be vacuum-actuated, i.e., actuated by applying a vacuum. The combined flow from turbine 116 and wastegate 90 then flows through an emission control device (see reference) before all or part of the treated exhaust gas can be released to the atmosphere via exhaust passage 35. Figure 2 (To be described separately).

[0031] Engine 10 can also include one or more exhaust gas recirculation (EGR) passages for recirculating a portion of exhaust gas from the exhaust manifold to the intake manifold. By recirculating some exhaust gas, engine dilution can be affected, which can improve engine performance by reducing engine knock, peak cylinder combustion temperature and pressure, throttling losses, and NOx emissions. In the depicted example, exhaust gas can be recirculated from the exhaust manifold 36 upstream of turbine 116 to the intake manifold 22 downstream of compressor 110 and throttle 20 via a high pressure EGR passage 84. This configuration can be referred to as a high pressure (HP) EGR system. EGR passage 84 can include a HP-EGR valve 86 for controlling the HP EGR flow and an EGR cooler for cooling the exhaust gas before it is delivered into the intake manifold. In a further example, exhaust gas can be recirculated from the exhaust passage 35 downstream of turbine 116 to the intake passage 42 upstream of compressor 110 via a low pressure (LP) EGR passage 190 to provide LP-EGR. Exhaust flow in the LP-EGR passage is controlled via a LP-EGR valve 52. The amount of EGR provided to the intake passage can be varied by controller 12 via the LP-EGR valve 52 and the HP-EGR valve 86. The controller can attribute an amount of desired EGR flow to the HP-EGR passage and the LP-EGR passage. As one example, if the amount of desired EGR flow is higher than the HP-EGR capacity, the controller opens the HP-EGR valve 86 fully and adjusts the opening of the LP-EGR valve 52 to provide the desired EGR flow.

[0032] Engine system 100 can also include a control system 14 that includes a controller 12. The illustrated controller 12 receives information from a plurality of sensors 16 (various examples of which are described herein) and sends control signals to a plurality of actuators 81 (various examples of which are described herein). As one example, sensors 16 can include a MAP sensor 124, an exhaust flow sensor 125, an exhaust temperature sensor 128, an exhaust pressure sensor 129, an intake temperature sensor 55, a compressor inlet pressure sensor 56, a manifold air flow sensor 57, and a throttle inlet pressure sensor 58. Other sensors, such as additional pressure sensors, temperature sensors, air-fuel ratio sensors, and composition sensors, can be coupled to various locations in engine system 10. In one example, a compressor speed sensor 54 can be coupled to compressor 110 to determine the rotational speed of the compressor. According to one non-limiting embodiment, compressor speed sensor 54 can be a passive vortex sensor. In one example, compressor speed sensor 54 can be a passive vortex sensor. Actuators 81 can include, for example, throttle 20, compressor recirculation valve 82, wastegate valve 92, direct fuel injectors 66, and intake port fuel injectors 67.

[0033] The control system 14 can be coupled to a navigation system 154 and wireless communication device 152. The navigation system 154 determines the location of the vehicle system 100 when turned on and at any other time. The location of the vehicle system 100 as estimated by the navigation system 154 (e.g., GPS coordinates of the vehicle) can be stored at the control system 14 for use during a drive cycle. The navigation system can be connected to an external server and / or network cloud 160 via wireless communication 150. The navigation system 154 can determine the current location of the vehicle system 100 and obtain traffic and road condition data from the network cloud 160 for use in controlling engine operation. Further, based on an operator selected destination, the navigation system 154 can provide various route options and then provide turn-by-turn instructions for navigating the vehicle system from a current location (e.g., a starting point) to the selected destination.

[0034] The controller 12 can also receive input data from the network cloud 160, one or more of vehicle-to-vehicle technology (V2V) 170 and vehicle-to-infrastructure technology (V2I) 180 via wireless communication 150 using the wireless communication device 152. V2V 180 can allow the control system 14 to communicate with other similarly equipped vehicles including wireless communication devices 172 to gather information about traffic and road conditions from infrastructure including wireless communication devices 182. In one example, V2V can indicate vehicle speeds along an intended route, such as whether other vehicles can be stopped ahead or whether there is stop-and-go traffic along a current route relative to an alternative route. In another example, V2I can indicate an upcoming red traffic light or a traffic accident along a predicted route. In this way, the vehicle system 100 can communicate with remote sources (e.g., external network cloud, other vehicles, infrastructure) using one or more technologies (e.g., wireless communication, navigation system, GPS, V2V, V2I).

[0035] Various data, including but not limited to gradient performance map data and upcoming traffic conditions, can be exchanged between the vehicle and the network cloud, and this data can be used to control vehicle operation. In one example, based on input from navigation system 154, controller 12 can identify driving patterns. Specifically, controller 12 can "learn" that the vehicle operator takes the same route to work each weekday morning. The controller can store data about the route, including road gradient information and / or expected traffic conditions, and, together with the learned driver model, can proactively control compressor casing handling to avoid predicted congestion or predicted surge conditions. The learned driver model can be developed by storing data related to the vehicle operator's habits. For example, over several weekday commutes, the controller can learn that during the morning commute, the driver exhibits relatively mild driving habits (e.g., indicated by gradual and infrequent actuation of the accelerator and brake pedals, resulting in gradual acceleration and intermittent braking). This type of driving behavior (referred to herein as a "mild driver pattern") can result in low-energy-density actuation of the accelerator pedal.

[0036] In this way, the vehicle controller 12 can communicate with the vehicle controllers of other vehicles via other corresponding navigation systems 154, via wireless communication devices 152 and / or via other forms of vehicle-to-vehicle (V2V) technology.

[0037] Based on instructions stored in the controller's memory or corresponding to one or more routines (such as...) Figure 6 In Example Method 600), the code programmed in which controller 12 employs actuator 81 in response to processed input data received from various sensors. As an example, controller 12 may determine whether the operating condition of compressor 110 is within a surge threshold. In one example, to determine the compressor operating condition relative to the surge threshold, the pressure ratio across the compressor and the compressor speed may be determined. In response to the compressor pressure being within a threshold margin defining the compressor's surge limit, controller 12 may send a control signal to actuator 117 to actuate the sleeve of the compressor 110's main drive housing to align the housing with the surge groove to provide a path for partially recirculating pressurized air back to the compressor inlet.

[0038] Now go to Figure 2 This shows an internal combustion engine (such as...) Figure 1 Example embodiment 200 of the combustion chamber (e.g., cylinder) of engine 10. Previously in Figure 1The components introduced in the foregoing description can be similarly numbered. Engine 10 can receive control parameters from a control system including controller 12 and inputs from a vehicle operator 230 via an input device 232. In this example, input device 232 includes an accelerator pedal and a pedal position sensor 234 for generating a proportional pedal position signal PP. Cylinder (also referred to herein as a "combustion chamber") 30 of engine 10 can include a combustion chamber wall 236 in which a piston 238 is positioned. Piston 238 can be coupled to a crankshaft 40 such that reciprocating motion of the piston is converted to rotational motion of the crankshaft. Crankshaft 40 can be coupled to at least one drive wheel of a vehicle system via a transmission system.

[0039] Cylinder 30 is capable of receiving intake air via intake passage 42, induction passage 43, and intake manifold 22. Intake manifold 22 can communicate with other cylinders of engine 10 in addition to cylinder 30. In some embodiments, one or more of the intake passages can include a supercharging device, such as a turbocharger or a mechanical supercharger. For example, Figure 2 Engine 10 is shown configured with a turbocharger 13 including a compressor 110 disposed between intake passage 42 and induction passage 43, and an exhaust turbine 116 disposed between exhaust manifold 36 and exhaust passage 35. Compressor 110 can be powered at least in part by exhaust turbine 116 via shaft 19, with the supercharging device configured as a turbocharger. As previously mentioned, in examples where engine 10 is provided with a mechanical supercharger, exhaust turbine 116 can optionally be omitted, with compressor 110 being powered by mechanical input from a motor or engine 10. Throttle 20 can include a throttle plate 264 and can be disposed along an intake passage of the engine for varying the flow rate and / or pressure of intake air provided to the engine cylinders. For example, throttle 20 can be disposed downstream of compressor 110, or alternatively, upstream of compressor 110.

[0040] Exhaust manifold 36 can receive exhaust gas from other cylinders of engine 10 in addition to cylinder 30. An exhaust sensor 228 is shown coupled to exhaust manifold 36 upstream of an emission control device 278, although it should be understood that this exhaust sensor 228 can be located at other locations in the exhaust system. Exhaust sensor 228 can be selected from a variety of suitable sensors for providing an indication of exhaust air-fuel ratio, such as, for example, a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a dual-cell oxygen sensor or EGO (as depicted), a HEGO (heated EGO), a NOx, HC, or CO sensor. Emission control device 278 can be a three-way catalyst (TWC), a NOx trap, various other emission control devices, or combinations thereof.

[0041] Each cylinder of engine 10 can include one or more intake valves and one or more exhaust valves. For example, the illustrated cylinder 30 includes at least one poppet-style intake valve 250 and at least one poppet-style exhaust valve 256 located at an upper region of cylinder 30. In some embodiments, each cylinder of engine 10, including cylinder 30, can include at least two poppet-style intake valves and at least two poppet-style exhaust valves located at an upper region of the cylinder.

[0042] Intake valve 250 can be controlled by controller 12 through cam actuation of cam actuation system 251. Similarly, exhaust valve 256 can be controlled by controller 12 through cam actuation of cam actuation system 253. Cam actuation system 251 and cam actuation system 253 can each include one or more cams and can utilize one or more of a cam profile switching (CPS) system, a variable cam timing (VCT) system, a variable valve timing (VVT) system, and / or a variable valve lift (VVL) system that can be operated by controller 12 to vary the timing of, and / or duration of, valve operation. Whether electronically or cam actuated, the timing of when the intake and exhaust valves open and close can be regulated in accordance with the prescribed parameters of the desired combustion and emissions control. The operation of intake and exhaust valves 250 and 256 can be determined by valve position sensors (not shown) and / or camshaft position sensors 255 and 257, respectively. In alternative embodiments, the intake and / or exhaust valves can be controlled by electric motor- driven valve actuation. For example, cylinder 30 can alternatively include an intake valve controlled via electric motor- driven valve actuation and an exhaust valve controlled via cam actuation including a CPS and / or VCT system. Moreover, the VCT system can include one or more VCT devices (not shown) that can be actuated to adjust the timing of the intake and exhaust valves to provide timing that offers reduced positive intake-to-exhaust valve overlap. That is, the intake and exhaust valves will be open for a shorter duration and will be moved away from being open at the same time for a portion of the intake stroke. In other embodiments, the intake and exhaust valves can be controlled by a common valve actuator or actuation system or a variable valve timing actuator or actuation system.

[0043] In some embodiments, each cylinder of engine 10 can include a spark plug 292 for initiating combustion. In selected modes of operation, ignition system 290 can provide an ignition spark to cylinder 30 via spark plug 292 in response to an ignition advance signal SA from controller 12. In other embodiments, a compression ignition engine can use a glow plug in place of spark plug 292.

[0044] In some embodiments, each cylinder of engine 10 can be configured with one or more injectors to deliver fuel to cylinder 30. By way of non-limiting example, cylinder 30 is shown as including two fuel injectors 66 and 67. Fuel injectors 66 and 67 can be configured to deliver fuel received from fuel system 288 via a high pressure fuel pump and fuel rail. Alternatively, fuel can be delivered at lower pressure by a single stage fuel pump, which case can be more limited in the timing of direct fuel injection during the compression stroke as compared to the case of using a high pressure fuel system. Additionally, the fuel tank can have a pressure sensor that provides a signal to controller 12.

[0045] Fuel injector 66 is shown as directly coupled to cylinder 30 for direct injection of fuel in cylinder 30 in proportion to the pulse width of a signal FPW-1 received from controller 12 via electronic driver 268. In this manner, fuel injector 66 provides so-called direct injection of fuel (hereinafter "DI") to combustion cylinder 30. While Figure 2 Injector 66 is shown as being positioned on one side of cylinder 30, but it can alternatively be positioned at the top of the piston, such as near spark plug 292. Such a location can improve mixing and combustion when operating the engine with alcohol-based fuels due to the lower volatility of some alcohol-based fuels. Alternatively, the injector can be positioned at the top and near the intake valve to improve mixing.

[0046] Fuel injector 67 is shown as being disposed in intake manifold 22 rather than in cylinder 30, which injector provides so-called port injection of fuel (hereinafter "PFI") into the intake port upstream of cylinder 30. Fuel injector 67 can inject fuel received from fuel system 288 in proportion to the pulse width of a signal FPW-2 received from controller 12 via electronic driver 271. Note that as depicted, a single electronic driver 268 or 271 can be used for both fuel injection systems, or multiple drivers can be used, for example, electronic driver 268 for fuel injector 66 and electronic driver 271 for fuel injector 67.

[0047] During a single cycle of the cylinder, fuel can be delivered to the cylinder by both injectors. For example, each injector can deliver a portion of the total fuel injection that is combusted in cylinder 30. Thus, even for a single combustion event, the injected fuel can be injected at different timings from the port injector and the direct injector. Further, for a single combustion event, multiple injections of the delivered fuel can be performed in each cycle. The multiple injections can be performed during the compression stroke, the intake stroke, or any suitable combination thereof.

[0048] As noted above, Figure 2Only one cylinder of a multi-cylinder engine is shown. Thus, each cylinder can similarly include its own set of intake / exhaust valves, fuel injector(s), spark plug, etc. It should be understood that the engine 10 can include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Additionally, each of these cylinders can include the reference cylinder 30 by Figure 2 Some or all of the various components described and depicted.

[0049] The engine can also include one or more exhaust gas recirculation passages for recirculating a portion of the exhaust gas from the engine exhaust to the engine intake. Thus, by recirculating some of the exhaust gas, engine dilution can be affected, which can improve engine performance by reducing engine knock, peak cylinder combustion temperature and pressure, throttling losses, and NOx emissions. In the depicted embodiment, exhaust gas can be recirculated from the exhaust passage 35 (e.g., downstream of the turbine 116) to the intake passage 42 (e.g., upstream of the compressor 110) via an LP-EGR passage 190. Additionally, an EGR sensor 245 can be disposed within the EGR passage 190 and can provide an indication of one or more of exhaust gas pressure, temperature, and concentration. Other non-limiting example EGR configurations can include HP-EGR (such as the HP-EGR passage 84 of FIG. 1) and / or a combination of LP-EGR and HP-EGR. Figure 1

[0050] The controller 12 is shown as a microcomputer including a microprocessor unit (CPU) 206, input / output ports (I / O) 208, an electronic storage medium for executable programs and calibration values shown as a read-only memory chip (ROM) 210 in this particular example, a random access memory (RAM) 212, a keep-alive memory (KAM) 214, and a data bus. The controller 12 can receive various signals from sensors coupled to the engine 10, including, in addition to those previously discussed, a measurement of engine coolant temperature (ECT) from a temperature sensor 216 coupled to a cooling jacket 218; a surface ignition sensing signal (PIP) from a Hall effect sensor 220 (or other type) coupled to the crankshaft 40; a throttle position (TPS) from a throttle position sensor; and a manifold absolute pressure signal (MAP) from a sensor 224. An engine speed signal RPM can be generated by the controller 12 from the signal PIP. The manifold pressure signal MAP from the manifold pressure sensor can be used to provide an indication of the vacuum or pressure in the intake manifold. Other sensors can include a fuel level sensor and a fuel composition sensor coupled to the fuel tank(s) of the fuel system.

[0051] ​The storage medium read-only memory chip 210 can be programmed with computer-readable data, which represents instructions executable by the microprocessor unit 206 for performing the methods described below and other variations contemplated but not specifically listed.

[0052] Controller 12 from Figure 1 to Figure 2 Various sensors receive signals and employ Figure 1 to Figure 2 Various actuators adjust engine operation based on received signals and instructions stored in the controller's memory. For example, in response to a surge margin at a compressor operating point within a threshold, the controller can send a signal to a compressor actuator coupled to a sleeve processed by the compressor's main actuator housing to actuate the sleeve to a surge position, where the surge port of the housing is open and the blockage port of the housing is closed. As another example, in response to a blockage margin at a compressor operating point within a threshold, the controller can send a signal to an actuator coupled to a sleeve processed by the compressor's main actuator housing to actuate the sleeve to a blockage position, where the blockage port of the housing is open and the surge port of the housing is closed.

[0053] Now go to Figure 3 Example 300 shows a cross-sectional view of a turbocharger 13 with Active Casing Processing (ACT) 310, as shown. Figure 1 and Figure 2 As shown in the image. Figure 1 and Figure 2 The components described herein will be similarly numbered. Turbine 116 converts the energy of exhaust gas into rotational energy to rotate the drive shaft 19 connected to impeller 340. Exhaust gas from exhaust manifold 36 enters turbine housing 380 through turbine inlet 360. The exhaust gas flows through volute passages 382 (e.g., 382a, 382b), expanding through turbine outlet 365 and exiting exhaust passage 35. The exhaust flow through turbine 116 generates force on one or more blades 370 coupled to hub 390, causing one or more blades 370, hub 390, and drive shaft 19 to rotate. Figure 3 Two blades 370a and 370b are shown, but those skilled in the art will recognize that more blades may be present in the turbine 116. The turbine blades 370 (e.g., 370a, 370b) include an inlet edge 370c, an outlet edge 370d, a hub edge 370e, and a casing edge 370f. In another embodiment, the turbine 116 may be a variable geometry turbine, wherein the exhaust flow through the turbine can be adjusted by actuating a turbine actuator 117.

[0054] Compressor 110 includes impeller 340, diffuser 330 (e.g., 330a, 330b), compressor chamber 322 (e.g., 322a, 322b), ACT 310, and casing 320. ACT 310 includes ACT sleeve 311 and ACT sleeve actuation arm 313. The position of ACT sleeve 311 can be adjusted by actuating ACT sleeve actuation arm 313 with controller 12. Rotation of impeller 340 draws charge air or gas into compressor 110 through compressor inlet 302 of casing 320. By way of non-limiting example, charge air or gas can include exhaust gas (such as when EGR is active), gaseous fuel (e.g., when port fuel injection is used), air from intake passage 42, and combinations thereof. This mixture of incoming gases can be collectively referred to as a “gas stream” or “air stream.” The gas flows from compressor inlet 302 and is accelerated by impeller 340 through diffuser 330 into compressor chamber 322. Diffuser 330 and compressor chamber 322 decelerate the gas, causing an increase in pressure in compressor chambers 322a, 322b. The gas under pressure can flow from compressor chambers 322a, 322b to intake manifold 22.

[0055] Elements in turbocharger 13 can be described relative to the direction of gas flow path through turbocharger 13. Elements substantially in the direction of gas flow relative to a reference point are downstream of the reference point. Elements substantially opposite the direction of gas flow relative to a reference point are upstream of the reference point. For example, compressor inlet 302 is upstream of impeller 340 upstream of diffuser 330. Diffuser 330 is downstream of impeller 340 downstream of compressor inlet 302.

[0056] Impeller 340 includes hub 354, full blades 350, and splitter 352. Full blades 350 and splitter 352 are attached to hub 354. The edge of the most upstream full blade 350 in compressor 110 is the leading edge of full blade 350. Similarly, splitter 352 includes a leading edge at the most upstream portion of splitter 352. The leading edge of full blade 350 is upstream of splitter 352. Impeller 340 includes a rotational axis that is aligned with the rotational axis of drive shaft 19 and turbine hub 390. The rotational axis is substantially parallel to the flow of gas at the compressor inlet and substantially perpendicular to the flow of gas at the diffuser.

[0057] The casing 320 includes a compressor inlet 302, an intake passage 304, a recirculation passage 318, a recirculation port 316, a discharge passage 317, a surge slot 312, and a choke slot 314. An impeller 340 is housed in the intake passage 304. The surge slot 312 is located on the casing 320 downstream of a leading edge of the full blade 350 and upstream of a leading edge of the splitter 352. The choke slot 314 is downstream of the leading edge of the splitter 352 and downstream of the surge slot 312 on the casing 320. The recirculation port 316 is downstream of the compressor inlet 302 and upstream of the impeller 340. The recirculation port 316 is configured to enable gas flow between the intake passage 304 and the recirculation passage 318.

[0058] The ACT 310 includes a plurality of ports 315 that cut into the sleeve 311. The ACT 310 is configured to control gas flow through the compressor 110. Specifically, the active casing treatment 310, controlled by the controller 12 via signals sent to the ACT sleeve actuation arm 313, can selectively control gas flow between the intake passage 304 and the recirculation passage 318 through one of the surge slot 312 and the choke slot 314. As described below, during conditions in which compressor surge can occur, such as in low mass flow conditions, the active casing treatment 310 can enable gas to flow from the intake passage 304 into the recirculation passage 318 through the surge slot 312. The gas further continues from the recirculation passage 318 into the intake passage 304 through the recirculation port 316. Thus, the gas flow impinging on the leading edge of the full blade 350 can be greater than if air were not allowed to flow through the surge slot 312. The additional flow of recirculated gas can enable the turbocharger compressor to operate with lower air flow through the compressor inlet 302 before surge occurs.

[0059] During conditions in which compressor choke can occur, such as in high mass flow conditions, the active casing treatment 310 can enable gas to flow from the impeller to the intake passage 304 via the choke slot 314 and the recirculation passage 318. During high mass flow conditions, a low pressure zone can exist in the intake passage 304 downstream of the leading edge of the splitter 352 proximate the choke slot 314. The low pressure zone can cause gas to flow from the intake passage 304 into the recirculation passage 318 through the recirculation port 316 and the discharge passage 317, and then into the impeller through the choke slot 314. The short circuit path through the recirculation passage 318 can enable gas flow through the compressor to increase in high mass flow conditions compared to a compressor without the choke slot 314. In this way, the short circuit flow of gas can enable more gas to flow before the turbocharger is in a choked flow condition.

[0060] The intake passage 304 can be substantially cylindrical. Because the recirculation passage 318 is external to the intake passage 304, the recirculation passage 318 can be substantially annular. The ports connecting the intake passage 304 and the recirculation passage 318, such as the recirculation port 316, the discharge passage 317, the choke slot 314, and the surge slot 312, can each be implemented in various means. For example, the ports can be configured as one or more holes formed in the casing. As another example, the ports can be configured as one or more slots extending around the circumference of the intake passage. The ports can have a uniform or non-uniform width along their length from the intake passage 304 to the recirculation passage 318. Each port can have a centerline extending along its length from the intake passage 304 to the recirculation passage 318. The centerline can be orthogonal to the axis of rotation of the impeller 340, or the centerline can have a non-zero slope when compared to being perpendicular to the axis of rotation of the impeller 340.

[0061] The active casing treatment 310 can be implemented in many ways. For example, a slidable casing sleeve 311 can be fitted in the recirculation passage to selectively block gas flow through the choke slot 314 and / or the surge slot 312. The casing sleeve can include one or more holes, ports, or slots 315 that selectively align with the choke slot 314 and / or the surge slot 312 depending on the position of the casing sleeve. Based on control signals received from the controller 12, the position of the casing sleeve 311 can be adjusted by actuating the ACT sleeve arm 313. For example, in response to a low mass flow condition or a condition when the compressor pressure ratio is within the surge margin to the surge limit, the casing sleeve arm 313 can be actuated to a first position via a signal commanded by the controller 12 at which the slots 315 of the casing sleeve align with the surge slot 312 and do not align with the choke slot 314. As a result, the casing sleeve can be adjusted so that the surge slot 312 is open and the choke slot 314 is blocked during the low mass flow condition. This allows gas to be recirculated from the impeller to the intake passage via the recirculation passage, further distancing the compressor operation from the surge limit.

[0062] As another example, in response to a high mass flow condition or a condition when the compressor pressure is within the choke margin to the choke limit, the casing sleeve arm 313 can be actuated to a second position (different from the first position) via a signal commanded by the controller 12 at which the ports or slots 315 of the casing sleeve align with the choke slot 314 and do not align with the surge slot 312. As a result, the casing sleeve can be adjusted so that the choke slot 314 is open and the surge slot 312 is blocked during the high mass flow condition. This allows gas to be recirculated from the intake passage to the impeller via the choke slot passage, further distancing the compressor operation from the choke limit.

[0063] In other examples, in response to a command from the controller 12 to adjust the position of the active casing treatment, the casing sleeve 310 can slide or rotate such that it does not overlap or obstruct the target port (e.g., choke slot 314 or surge slot 312) in any way, thereby selectively opening the choke slot 314 or surge slot 312. These positions will be referenced as Figure 4A to Figure 4B Further description. In alternative embodiments, the active casing treatment 310 can be adjusted based on the pressure differential across the compressor inlet 304 and the intake manifold 44. In yet another alternative embodiment, the active casing treatment 310 can be adjusted based on the pressure differential across the intake manifold 44 and the turbine inlet 360. It should be understood that these specific embodiments are presented by way of example and are not intended to be limiting in any way.

[0064] Turning now to Figure 4A to Figure 4B , an example actuation of a sleeve of a compressor active casing treatment, such as the ACT sleeve 311 of Figure 3 , and the flow pattern generated by the compressor is shown. Figure 4A An embodiment 400 of Figure 3 shows a cross-sectional view of the compressor 100, with the sleeve of the active casing treatment in a surge position enabling surge control. Figure 4B An embodiment 450 of Figure 3 shows a cross-sectional view of the compressor 100, with the sleeve of the active casing treatment in a choke position enabling choke control. It should be understood that Figure 4A to Figure 4B all of the components shown in

[0065] Figure 4A An example first positioning 400 of the active casing treatment 311 in response to a low mass flow condition that can cause the compressor to operate within surge limits is shown. For example, in response to a compressor pressure ratio within surge margin to surge limit, the controller can send a control signal to the ACT sleeve arm 313 to move the ACT sleeve 311 to a first position in which the slot 315 overlaps the surge port 312. In this position, the surge port is open and the choke port is closed. As a result of actuating the sleeve to the first position, the active casing treatment 310 can enable air to flow from the intake passage 304 through the surge slot 312 and the slot 315 into the recirculation passage 318 during the low mass flow condition. The air flow then continues from the recirculation passage 318 into the intake passage 304 through the recirculation port 316, as shown by the dashed arrow 452. Thus, the flow of air charge hitting the leading edge of the full blade 350 can be greater than if the surge slot 312 were closed / obstructed by the sleeve, as shown in Figure 4B

[0066] Figure 4B ​A second example positioning 450 of the active casing treatment 310 responsive to high mass flow conditions that can cause the compressor to operate within the threshold of the choke limit is shown. For example, in response to the compressor pressure ratio being within the choke margin to the choke limit, the controller can send a control signal to the ACT sleeve arm 313 to move the ACT sleeve 311 to a second position in which the choke slot 314 overlaps the choke port. In this position, the surge port is closed and the choke port is open. In particular, during high mass flow conditions, a low pressure region can exist in the intake passage 304 downstream of the leading edge of the splitter 352 adjacent to the choke slot 314. As shown in 452, the low pressure region can cause gas to flow from the intake passage 304 through the recirculation port 316 into the recirculation passage 318, and back into the intake passage 304 through the choke slot 314. The short circuit path through the recirculation passage 318 can enable an increase in gas flow through the compressor during high mass flow conditions when compared to a compressor without the choke slot 314. In this way, the short circuit flow of gas can enable more gas to flow before the turbocharger is in a choked condition.

[0067] It should be appreciated that, Figure 3 and Figure 4A to Figure 4B The ACT mechanism of the'1 1 1 patent describes a movable sleeve in a three position system that regulates the opening of two different flow slots in the compressor, namely the choke slot and the surge slot. Herein, the three positions include a nominal position in which both the choke slot and the surge slot are closed, a surge position in which only the choke slot is closed, and a choke position in which only the surge slot is closed. However, in alternative embodiments, the ACT mechanism can be coupled in a two position system with only one controlled slot, namely the choke slot. Herein, the two positions are a nominal position in which the choke slot is closed and a choke position in which the choke slot is open, with the surge slot being uncontrolled and operating via passive operation, and the default nominal providing increased surge margin.

[0068] Figure 3 and Figure 4A to Figure 4BExample configurations showing relative positioning of various components. If shown directly contacting or coupling to one another, such elements in at least one example can be referred to as directly contacting or directly coupled. Similarly, elements shown abutting or adjacent one another can be referred to as abutting or adjacent one another, respectively, in at least one example. As one example, components placed in contact with one another that are coplanar can be referred to as coplanarly contacting. As another example, elements positioned apart from one another with only space there-between and without other components there-between can be so referred to in at least one example. As yet another example, elements shown above / below one another, on opposite sides of one another, or to the left / right of one another can be so referred to relative to one another. Additionally, as shown in the figures, in at least one example, the topmost element or point of an element can be referred to as the "top" of the component, and the bottommost element or point of an element can be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the figures and used to describe the positioning of elements of the figures relative to one another. As such, in one example, an element shown above other elements is positioned vertically above the other elements. As yet another example, the shapes of elements depicted within the figures can be referred to as having those shapes (e.g., such as circular, straight, planar, curved, rounded, chamfered, angled, etc.). Additionally, in at least one example, elements shown intersecting one another can be referred to as intersecting elements or intersecting one another. Further, in one example, an element shown within another element or shown external to another element can be so referred to.

[0069] In this way, Figure 1 to Figure 4B The components of the system provide a boosted engine system, comprising: an engine; an intake compressor having an impeller, a choke slot, a surge slot, an actuatable annular casing containing the impeller, the casing including a sleeve slot, and an actuator coupled to the sleeve of the casing; an exhaust turbine; an EGR valve coupled to an EGR passage for recirculating exhaust from an engine output to an engine input; a pedal for receiving operator torque demand; and a controller. The controller can be programmed to control gas flow and pressure via a feedback control loop. The controller can be further programmed to actuate the ACT casing in response to a predicted compressor surge or choke. Upon actuating the ACT casing, the controller also adjusts EGR flow and turbine flow via a feedforward control signal to reduce disturbance in gas flow and pressure due to ACT actuation.

[0070] Figure 5An example control block 500 for controlling gas flow and pressure of an engine 515 is shown. The control block 500 includes a feedback control loop 510 and a feedforward control block 520. The feedback control loop controls the engine gas flow and pressure to a desired gas flow 504 and a desired pressure 503 based on feedback from a measured gas flow 517 and a measured pressure 516. The engine gas flow can include one or more of EGR flow, mass air flow into the cylinder, or exhaust flow. The engine pressure can include one or more of engine intake manifold pressure, boost pressure, and engine exhaust manifold pressure. The engine gas flow and pressure can be adjusted by actuating a first actuator with a control signal 512 and a second actuator with a control signal 513. In one example, the first actuator can be used to control EGR flow and the second actuator can be used to control turbo flow. In another example, the first actuator can include an EGR valve. In another example, the first actuator can include both an EGR valve and a throttle (such as throttle 20 of Figure 1 The feedback control signals 507 and 508 can be generated by a feedback controller 514 based on inputs including engine speed 501, fueling parameter 502, gas flow error 505, and pressure error 506. The gas flow error 505 is the difference between the desired gas flow 504 and the measured gas flow 517. The pressure error is the difference between the desired pressure 503 and the measured pressure 516. The first actuator and the second actuator are actuated by the control signals 512 and 513. If the compressor geometry is not adjusted, the first actuator and the second actuator are directly actuated by the control signals 507 and 508. In other words, when the compressor actuator is not adjusted, the control signal 512 is equal to the feedback control signal 507 and the control signal 513 is equal to the feedback control signal 508. During compressor geometry adjustment, the control signals to the first actuator or the second actuator are based on the feedback control signals and the feedforward control signals. For example, the control signal 512 to the first actuator is equal to the difference between the feedback control signal 507 and the feedforward control signal 511; the control signal 513 to the second actuator is equal to the difference between the feedback control signal 508 and the feedforward control signal 509.

[0071] The compressor geometry error 523 between the desired compressor geometry / position 521 and the measured compressor geometry / position 522 is used by a feedforward controller 524 to generate feedforward control signals 509 and 511. In one example, the compressor geometry error 523 can be an amount of adjustment in the compressor geometry. In another example, the compressor geometry error 523 can be a change in the compressor actuator position from a current compressor actuator position to a desired compressor actuator position. The compressor geometry 523 can be used to actuate the compressor actuator. As an example, the feedforward controller 524 can calculate the feedforward control signals based on a sensitivity of EGR flow with respect to the first actuator, a sensitivity of EGR flow with respect to the second actuator, a sensitivity of pressure with respect to the second actuator, a sensitivity of pressure with respect to the first actuator, a sensitivity of EGR flow with respect to the compressor actuator, and a sensitivity of pressure with respect to the compressor actuator. Details of the feedforward controller 524 are further presented in Figure 6 .

[0072] Figure 6 An example method 600 for controlling an engine system including a variable geometry compressor is shown. In particular, gas flow and pressure of the engine system are controlled via a feedback control loop, such as the feedback control loop 510 of Figure 5 . In response to compressor surge or choke, EGR flow, turbine flow, and compressor geometry are adjusted via both the feedback control loop and a feedforward control block, such as the feedforward control block 520 of Figure 5 , to maintain substantially constant (e.g., within 5% of the mean) gas flow and pressure. The amount of adjustment to the compressor geometry is used to determine adjustments to the EGR flow and turbine flow. After the compressor geometry is adjusted, the gas flow and manifold pressure are controlled only by the feedback control loop and not by the feedforward control block.

[0073] The instructions for implementing the method 600 and the remaining methods included herein can be executed by a controller based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the engine system, such as the sensors described above with reference to Figure 1 to Figure 2 . In accordance with the methods described below, the controller can employ engine actuators of the engine system to adjust engine operation.

[0074] At 601, the method 600 estimates and / or measures engine operating conditions, including but not limited to as can be through reference to Figure 1 and Figure 2The outputs of the various sensors described are used to measure and / or estimate engine speed, fuel quantity, fuel pressure, operator torque demand, engine coolant temperature (ECT), barometric pressure (BP), boost pressure, intake manifold pressure (boost pressure), exhaust manifold pressure, mass air flow rate (MAF), exhaust flow rate, accelerator pedal position (PP), EGR flow, and EGR rate.

[0075] At 602, the method 600 measures or estimates a gas flow rate and pressure controlled via a feedback control loop, such as the feedback control loop 510 of Figure 5 In one example, the gas flow rate can be an exhaust flow rate. In another example, the gas flow rate can be a mass air flow rate. In yet another example, the gas flow rate can be an exhaust flow rate. The manifold pressure can be either an intake manifold pressure (boost pressure) or an exhaust manifold pressure. In another example, an EGR rate and a boost pressure are controlled via a feedback control loop.

[0076] At 603, the gas flow rate and pressure can be adjusted via the feedback control loop based on the measurements at 602. In particular, a control signal to an engine actuator can be determined by a feedback controller, such as the feedback controller 514 of Figure 5 based on a difference between a desired gas flow rate and manifold pressure and a measured gas flow rate and manifold pressure. The feedback controller can be, for example, a PID controller. The feedback control signal to the engine actuator can be further determined based on engine operating parameters, such as engine speed and fueling. The engine actuator can include a first actuator for controlling an EGR flow rate and a second actuator for controlling a turbo flow rate. The actuators are operated based on control signals, such as the control signals 507 and 508 of Figure 5 to adjust the gas flow rate and pressure to a desired setpoint.

[0077] At 604, the method 600 determines whether to adjust a geometry or position of the compressor. A controller, such as the controller 12 of Figure 1 may determine whether to adjust the compressor based on a current compressor operating point within a compressor performance map, such as the performance map 800 of Figure 8 The compressor operating point can include an air flow rate through the compressor and a pressure ratio across the compressor. In one embodiment, the compressor geometry can be adjusted in response to a surge margin or choke margin being less than a threshold value. In another embodiment, the compressor geometry can be adjusted in response to the compressor operating in a surge region or a choke region. In another embodiment, the compressor geometry can be adjusted based on compressor efficiency. For example, the compressor can be adjusted if the compressor efficiency can be improved. In yet another embodiment, the compressor geometry can be adjusted based on driver behavior, such as frequent actuation of an accelerator pedal or a brake pedal.

[0078] In one embodiment, the compressor includes an ACT, and the compressor geometry can be adjusted by actuating the case sleeve to align the sleeve from the nominal position to the surge slot or the choke slot. For example, in response to a sharp throttle up, in response to a compressor surge margin that is less than a threshold, the controller can determine to adjust the compressor geometry by actuating the ACT and move the compressor from the nominal position to the surge position, where the case sleeve is aligned with the surge slot. As another example, after moving the compressor to the surge position, in response to an increased compressor air flow and a decreased compressor pressure ratio, the controller can determine to adjust the compressor geometry by actuating the compressor from the surge position to the nominal position to improve compressor efficiency.

[0079] If the controller determines not to adjust the compressor, the method 600 moves to 605, where the engine operating conditions are continued to be monitored. Otherwise, the controller determines to adjust the compressor.

[0080] At 606, the controller determines a desired compressor geometry. In one embodiment, the desired compressor geometry can be a position of the ACT compressor, such as a surge position, a nominal position, and a choke position. In another embodiment, the desired compressor geometry can be a desired opening angle of the compressor blades. The desired compressor geometry can be determined based on the compressor operating point and the compressor performance map. For example, the desired opening angle of the compressor blades can decrease as the surge margin decreases. As another example, in response to a decreased surge margin, the ACT actuator can be moved to open the surge slot.

[0081] The controller can further determine a desired compressor operating point after adjusting the compressor geometry. The desired compressor operating point can be determined based on the desired boost pressure and the fresh air flow determined during the engine mapping.

[0082] At 607, the method 600 determines a first amount of the compressor geometry adjustment, a second amount of the EGR flow adjustment, and a third amount of the turbine flow adjustment. The amount of the compressor geometry adjustment can be obtained by comparing the desired compressor geometry with the measured compressor geometry. In one example, the amount of the compressor geometry adjustment corresponds to a change in the compressor actuator position.

[0083] In one embodiment, the compressor includes an ACT, and the amount of the compressor adjustment can be a change in the gas flow from a current compressor position to a desired compressor position. For example, the amount of the compressor adjustment can be a change in the gas flow from the nominal compressor position to the surge position, or a change in the gas flow from the compressor surge position to the nominal position.

[0084] In another embodiment, the compressor can be a variable geometry compressor with adjustable vanes, where the compressor geometry can continue to be adjusted via a compressor actuator. As an example, the amount of compressor adjustment can be quantified and converted to an amount of change in compressor actuator position. As another example, the amount of compressor adjustment can be a change in vane position in degrees.

[0085] The second amount of adjustment to EGR flow and the third amount of adjustment to turbine flow can be determined based on the amount of compressor geometry adjustment. As one example, the EGR flow is adjusted via a first actuator and the turbine flow is adjusted via a second actuator. The amount of change or adjustment to EGR flow and turbine flow can be calculated based on a change in position of the compressor actuator, a sensitivity of EGR flow with respect to the first actuator, a sensitivity of EGR flow with respect to the second actuator, a sensitivity of pressure with respect to the second actuator, a sensitivity of pressure with respect to the first actuator, a sensitivity of EGR flow with respect to the third actuator, and a sensitivity of pressure with respect to the third actuator. The sensitivity of flow with respect to an actuator is defined as a change in flow rate of flow resulting from a change in the actuator.

[0086] In one embodiment, the gas flow and pressure are controlled via a feedback control loop. The predicted change in gas flow AF and pressure Ap due to compressor geometry adjustment can be calculated as

[0087]

[0088] where AVC is the amount of compressor geometry adjustment; dF / dvgc and dp / dvgc are the sensitivities of gas flow and pressure with respect to the compressor actuator, respectively. The expected change in gas flow AF and pressure Ap due to compressor geometry adjustment can alternatively be depicted as

[0089]

[0090] where Aegr and Avgt are the amounts of change in EGR flow and turbine flow; dF / dAegr, dF / dvg, dp / dvgt, and dp / dvgt are the sensitivities of gas flow with respect to the first actuator, the sensitivity of gas flow with respect to the second actuator, the sensitivity of pressure with respect to the first actuator, and the sensitivity of pressure with respect to the second actuator, respectively.

[0091] From Equations 1 and 2, the amounts of change or adjustment to EGR flow and turbine flow can be calculated from the amount of compressor geometry adjustment via a feedforward controller, such as the feedforward controller 524 of Figure 5 From Equations 1 and 2, the amounts of change or adjustment to EGR flow and turbine flow can be calculated from the amount of compressor geometry adjustment via a feedforward controller, such as the feedforward controller 524 of

[0092]

[0093] The adjustments in EGR flow and turbine flow can be subtracted from the feedback control signals to actuate the first and second actuators to reduce disturbances in gas flow and pressure due to the compressor geometry adjustment.

[0094] At 608, while the compressor actuators are actuated to move the compressor to the desired compressor geometry, the EGR flow and turbine flow are adjusted based on the amounts of adjustment in EGR flow and turbine flow determined at 507.

[0095] At 609, the method 600 checks whether the compressor has been adjusted to the desired geometry determined at 606. If the answer is yes, the method 600 moves to 611. If the answer is no, the method 600 moves to 610, where the compressor geometry is continued to be adjusted and the EGR flow and turbine flow are also continued to be adjusted while the compressor actuators are actuated.

[0096] At 611, after the compressor geometry is adjusted, the gas flow and pressure are controlled via a feedback control loop instead of the feedforward control block. In other words, the control signals (such as 509 and 511) generated by the feedforward control loop are zero. In addition, the EGR flow and turbine flow can be adjusted to move the compressor operating point to the desired compressor operating point at 606. Figure 5

[0097] By adjusting the EGR flow and turbine flow based on the expected changes caused by the compressor geometry adjustment, the method 600 can maintain substantially constant engine gas flow and pressure during the compressor actuator operation. Therefore, transient disturbances due to the compressor adjustment can be prevented or reduced.

[0098] Figure 7 An example timeline of engine operating parameters (accelerator pedal pressure 710, boost pressure 720, compressor pressure ratio 730, and EGR rate 750) and states of engine actuators (ACT 740, EGR valve 760, and VGT vanes 770) is shown when the method of Figure 6 At tl, in response to an increase in the accelerator pedal pressure, the boost pressure and the compressor pressure ratio increase. The ACT is at the nominal position. In response to the increased boost pressure, the EGR valve opening can start to decrease, and the EGR rate can accordingly decrease. The opening of the VGT vanes is high.

[0099] From tl to t2, the gas flow and pressure are controlled via a feedback control loop (such as 507 and 509) instead of the feedforward control block (such as 501 and 503). In other words, the control signals (such as 501 and 503) generated by the feedforward control loop are zero. In addition, the EGR flow and turbine flow are adjusted to move the compressor operating point to the desired compressor operating point at 606.

[0100] Figure 5 ​​The feedback control loop 510 controls the boost pressure and EGR rate to the desired values, while the compressor geometry remains unchanged (ACT is maintained at the nominal position). This is achieved via feedback control signals (such as...). Figure 5 Control signals 507 and 508 actuate the EGR valve and VGT vanes to adjust the boost pressure and EGR rate. As the accelerator pedal pressure increases, the opening of the EGR valve decreases and the opening of the VGT vanes decreases.

[0101] From t2 to t3, the accelerator pedal pressure remains high. Based on feedback control, the boost pressure remains at a high level, while the EGR rate remains at a low level.

[0102] At t3, in response to the sharp drop in accelerator pedal pressure from a high level, the controller (such as...) Figure 1 The controller 12) determines that surge may occur and begins actuating the ACT from the nominal position to the surge slot. Simultaneously, the EGR valve and VGT vanes are actuated to counteract the potential transient increase in boost pressure 721 and the transient increase in EGR rate 751. For example, the feedforward control signal (such as...) can be subtracted from the feedback control signal. Figure 5 (509 and 511) to actuate the EGR valve and VGT vane. Thus, based solely on the feedback control signal, the opening degree of the EGR valve can be lower than the EGR valve opening degree 761; and based solely on the feedback control signal, the opening degree of the VGT vane can be greater than the VGT vane opening degree 771. In this way, during and immediately after the actuation of ACT, the boost pressure and EGR rate remain substantially constant (e.g., within 5% of the average value).

[0103] At t4, after ACT actuation, the EGR rate and boost pressure are controlled by a feedback control loop rather than a feedforward control block. The EGR valve and VGT vanes can be actuated to move the compressor operating point to the optimal position.

[0104] At t5, based on the engine operating condition, the controller can determine to adjust ACT from the surge position to the nominal position. As an example, the controller can adjust ACT to improve compressor efficiency. The EGR valve and VGT vanes are actuated by feedback control signals and feedforward control signals to reduce disturbances 722 to the boost pressure and 752 to the EGR rate. For example, the opening of the EGR valve can be greater than the valve opening 762 without adjustment by the feedforward control signal. The VGT vanes may be more closed compared to those adjusted without the feedforward control signal. Therefore, the boost pressure and EGR rate remain substantially constant during and immediately after ACT actuation from t5 to t6. By adjusting ACT to the surge groove, the compressor pressure ratio does not increase further as shown in 731, and compressor surge is prevented by improving the surge margin.

[0105] From t6 to t7, boost pressure and EGR rate are controlled only via feedback control loops.

[0106] At t7, the accelerator pedal pressure is sharply increased from low to high. The controller determines that compressor stall can occur and actuates the ACT from the nominal position to the stall position. The EGR valve and the VGT vanes are also actuated to counteract the disturbance caused by the ACT adjustment. For example, the EGR valve opening can be increased compared to the EGR valve opening 763 actuated by the feedback control signal alone. In another example, the EGR flow can be distributed to both the HP-EGR flow and the LP-EGR flow. If the HP-EGR valve is at its maximum opening, the opening of the LP-EGR valve can be increased to increase the EGR flow. The VGT vane opening can be decreased compared to the VGT vane opening 773 actuated by the feedback control signal alone. By adjusting the EGR flow and the turbine flow when the ACT is actuated, the engine boost pressure and the EGT rate are maintained substantially constant during and immediately after the ACT actuation. By actuating the ACT, the compressor pressure ratio does not drop as shown in 732, and the compressor stall can be prevented by extending the stall flow capacity.

[0107] At t8, after increasing the air flow through the compressor, the ACT can be activated from the stall position to the nominal position. The EGR valve and the VGT vanes are simultaneously activated by the ACT to reduce the transient increase in boost pressure 724 and the transient increase in EGR rate 754. For example, the EGR valve opening can be decreased compared to the EGR valve opening 764 actuated by the feedback control signal alone. The VGT vane opening can be increased compared to the VGT vane opening 774 actuated by the feedback control signal alone.

[0108] In another embodiment, the actuation of the VGT vanes can be replaced by the actuation of the wastegate or the turbine flow can be adjusted by actuating the wastegate together with the VGT vanes.

[0109] Figure 8 An example compressor performance map 800 showing the compressor pressure ratio (along the y-axis) at different compressor flow rates (along the x-axis). Line 809 represents the isentropic efficiency. Line 802 (solid line) represents the surge limit (e.g., hard surge limit), while line 804 (dashed line) represents the stall limit. The solid line 806 depicts a substantially constant compressor speed line. Compressor operation to the left of the surge limit results in turbocharger compressor operation in the surge region. Likewise, compressor operation to the right of the stall limit 804 results in turbocharger compressor operation in the stall region. Compressor operation in both the surge region and the stall region results in objectionable NVH and potential degradation of the boosted engine performance.

[0110] As an example, the surge margin can be determined as:

[0111] Surge margin = (mass flow rate nom - mass flow rate surge line) / mass flow rate nom, where mass flow rate nom is the nominal mass flow rate and mass flow rate surge line is the mass flow rate at the surge line. All mass flow rates can be calculated from the compressor performance map at the same corrected compressor speed. The choke margin can be determined similarly. For example, the surge margin of operating point 820 is 807; the choke margin of operating point 830 is 808.

[0112] Adjusting the geometry or position of the compressor can expand the operating range of the compressor and improve the compressor efficiency. For example, adjusting the compressor geometry can change the isentropic efficiency from 812 to 810. As a result, the surge margin can also increase.

[0113] In this way, by introducing a feed forward control signal to control the EGR flow and turbine flow, the disturbance of the engine operating parameters due to the adjustment of the compressor geometry can be avoided. The feed forward control signal can be introduced simultaneously with the activation of the compressor actuator. The technical effect of adjusting the compressor geometry is that the compressor surge margin or choke margin can be improved and the compressor can reliably provide the boost pressure. In addition, the compressor efficiency can be improved. The technical effect of adjusting the turbine flow and EGR flow when adjusting the compressor geometry is to avoid the disturbance of the engine operating parameters of the feedback control.

[0114] As one embodiment, a method for an engine includes adjusting exhaust gas recirculation (EGR) flow via a first actuator and adjusting turbine flow via a second actuator while adjusting geometry of a compressor, where the EGR flow and the turbine flow are adjusted based on the adjustment of the compressor geometry. In a first example of the method, the EGR flow and the turbine flow are adjusted to maintain a substantially constant gas flow and a substantially constant pressure during the adjustment of the compressor geometry. A second example of the method optionally includes the first example, and further includes where the gas flow includes mass air flow, and the first actuator includes a throttle. A third example of the method optionally includes one or more of the first example and the second example, and further includes where the gas flow includes EGR flow, and the first actuator includes an EGR valve. A fourth example of the method optionally includes one or more of the first example through the third example, and further includes where the first actuator further includes a throttle. A fifth example of the method optionally includes one or more of the first example through the fourth example, and further includes where the pressure is an exhaust pressure or a boost pressure. A sixth example of the method optionally includes one or more of the first example through the fifth example, and further includes the second actuator is a wastegate or a variable geometry turbine. A seventh example of the method optionally includes one or more of the first example through the sixth example, and further includes measuring the gas flow and the pressure, and adjusting the gas flow and the pressure based on the measured gas flow and the measured pressure without adjusting the geometry of the compressor. An eighth example of the method optionally includes one or more of the first example through the seventh example, and further includes where the geometry of the compressor is adjusted via a third actuator, and a change in position of the third actuator is determined based on an amount of the adjustment of the compressor geometry. A ninth example of the method optionally includes one or more of the first example through the eighth example, and further includes adjusting the EGR flow and the turbine flow based on the change in position of the third actuator, a sensitivity of the EGR flow with respect to the first actuator, a sensitivity of the EGR flow with respect to the second actuator, a sensitivity of the pressure with respect to the second actuator, a sensitivity of the pressure with respect to the first actuator, a sensitivity of the EGR flow with respect to the third actuator, and a sensitivity of the pressure with respect to the third actuator.

[0115] As another example, a method for a turbocharged engine includes adjusting EGR flow and turbine flow in response to EGR rate and boost pressure; determining a first amount of compressor geometry adjustment; determining a second amount of EGR flow adjustment and a third amount of turbine flow adjustment based on the first amount of compressor geometry adjustment; and simultaneously adjusting compressor geometry by the first amount, adjusting EGR flow by the second amount, and adjusting turbine flow by the third amount. In a first example of the method, wherein EGR rate and boost pressure are maintained substantially constant while adjusting compressor geometry. A second example of the method optionally includes the first example, and further includes wherein EGR flow is adjusted by actuating an EGR valve and a throttle. A third example of the method optionally includes one or more of the first example and the second example, and further includes adjusting EGR flow and turbine flow in response to EGR rate and boost pressure after adjusting compressor geometry. A fourth example of the method optionally includes one or more of the first example and the third example, and further includes adjusting EGR flow and turbine flow based on EGR rate and boost pressure while adjusting compressor geometry.

[0116] As another example, an engine system includes a compressor for supplying boosted air to an engine, wherein a geometry of the compressor is adjustable by actuating a compressor actuator; a turbine coupled to the compressor; an EGR passage for recirculating exhaust gas from an engine output to an engine intake; an EGR valve coupled to the EGR passage for controlling EGR flow; a first sensor coupled to the engine for measuring gas flow; a second sensor coupled to the engine for measuring manifold pressure; and a controller having computer readable instructions stored on non-transitory memory, the controller configured for: adjusting the gas flow and the manifold pressure based on outputs of the first sensor and the second sensor; determining an adjustment amount of the compressor actuator; determining an expected change in the gas flow and an expected change in the manifold pressure based on the adjustment amount of the compressor actuator; actuating the compressor actuator by the determined adjustment amount; and adjusting the EGR flow and the turbine flow to compensate for the expected change in the gas flow and the expected change in the manifold pressure while actuating the compressor actuator. In a first example of the system, the controller is further configured for adjusting the gas flow and the manifold pressure based on outputs of the first sensor and the second sensor after actuating the compressor actuator. A second example of the system optionally includes the first example and further includes wherein a pressure ratio across the compressor is maintained substantially constant while actuating the compressor actuator. A third example of the method optionally includes one or more of the first system and the second system and further includes wherein the compressor is a positive casing compressor, the change amount of the actuator is a first amount when the compressor is adjusted from a nominal position to a surge position, and the change amount of the actuator is a second amount when the compressor is adjusted from the nominal position to a choked position. A fourth example of the method optionally includes one or more of the first system and the third system and further includes wherein the EGR passage includes a low pressure EGR passage and a high pressure EGR passage, and adjusting the EGR flow further includes distributing the EGR flow between the low pressure EGR passage and the high pressure EGR passage.

[0117] Note that the example control and estimation routines included herein can be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transitory memory and can be executed by a control system comprising a controller in combination with various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and so on. As such, the various acts, operations, and / or functions illustrated can be performed in the manner shown, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily restricted to that shown unless specifically stated. The examples described herein are used as smoke screens simply to help explain and illustrate the examples described herein. In terms of real-time implementation, as used herein "real-time" and "real-time system" are used to describe systems operating in real-time, near real-time, and / or in a timely manner. Based on the particular strategy being used, one or more of the acts or operations illustrated can be repeated the number of times indicated, iteratively (i.e., within a loop), and / or performed based on calls to the code even, out of the loop, in a "delayed" manner. Further, the described acts and / or functions can graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the engine control system, where the described acts are carried out by executing the instructions in the system including the various engine hardware components in combination with the electronic controller.

[0118] It should be understood that the arrangements and routines disclosed herein are exemplary in nature, and that numerous variations are possible without departing from the characteristics of the disclosure. For example, the above-described techniques can be applied to V-6, I-4, I-6, V-12, opposed 4 cylinder, and other engine types. The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems and configurations, and other features, functions, and / or properties disclosed herein.

[0119] The appended claims particularly point out certain combinations and subcombinations considered to be novel and nonobvious. These claims can refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood as including one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties can be claimed through amendment of the present claims or presentation of additional claims in this or a related application. Such newly amended or presented claims, whether they differ from the original application claims or not, are also intended to be within the subject matter of the claims of the disclosure.

Claims

1. A method for an engine, comprising: adjusting an exhaust gas recirculation (EGR) flow and a turbine flow via a first actuator and a second actuator while adjusting a geometry of a compressor, comprising: determining an amount of adjustment of the geometry of the compressor; determining an expected change in gas flow and an expected change in manifold pressure based on the amount of adjustment of the geometry of the compressor; adjusting the geometry of the compressor by the amount of adjustment; and adjusting the EGR flow and turbine flow to compensate for the expected change in gas flow and the expected change in manifold pressure while adjusting the geometry of the compressor.

2. The method of claim 1, wherein the EGR flow and the turbine flow are adjusted to maintain a substantially constant gas flow and a substantially constant pressure during the compressor geometry adjustment.

3. The method of claim 2, wherein the gas flow comprises a mass air flow and the first actuator comprises a throttle.

4. The method of claim 1, wherein the first actuator comprises an EGR valve.

5. The method of claim 4, wherein the first actuator further comprises a throttle.

6. The method of claim 2, wherein the pressure is an exhaust pressure or a boost pressure.

7. The method of claim 2, wherein the second actuator is a wastegate or a variable geometry turbine.

8. The method of claim 2, further comprising measuring the gas flow and the pressure and adjusting the gas flow and the pressure based on the measured gas flow and the measured pressure without adjusting the geometry of the compressor.

9. The method of claim 1, wherein the geometry of the compressor is adjusted via a third actuator and a change in position of the third actuator is determined based on an amount of the compressor geometry adjustment.

10. The method of claim 9, further comprising adjusting the EGR flow and the turbine flow based on the change in position of the third actuator, a sensitivity of the EGR flow with respect to the first actuator, a sensitivity of the EGR flow with respect to the second actuator, a sensitivity of pressure with respect to the second actuator, a sensitivity of the pressure with respect to the first actuator, a sensitivity of the EGR flow with respect to the third actuator, and a sensitivity of the pressure with respect to the third actuator.

11. An engine system, comprising: a compressor for supplying boost air to an engine, wherein a geometry of the compressor can be adjusted by actuating a compressor actuator; a turbine coupled to the compressor; an EGR passage for recirculating exhaust gas from an engine output to an engine intake; an EGR valve coupled to the EGR passage for controlling an EGR flow; a first sensor coupled to the engine for measuring a gas flow; and a controller coupled to the compressor actuator, the turbine, the EGR valve, and the first sensor for adjusting the geometry of the compressor, the EGR flow, and the turbine flow. a second sensor coupled to the engine for measuring manifold pressure; and a controller having computer readable instructions stored on non-transitory memory, the controller configured to: adjust the gas flow and the manifold pressure based on outputs of the first sensor and the second sensor; determine an adjustment amount for the compressor actuator; determine an expected change in the gas flow and an expected change in the manifold pressure based on the adjustment amount for the compressor actuator; actuate the compressor actuator by the adjustment amount; and adjust the EGR flow and turbine flow to compensate for the expected change in gas flow and the expected change in manifold pressure when actuating the compressor actuator.

12. The engine system of claim 11, wherein the controller is further configured to adjust the gas flow and the manifold pressure based on outputs of the first sensor and the second sensor after actuating the compressor actuator.

13. The engine system of claim 11, wherein a pressure ratio across the compressor is maintained substantially constant when actuating the compressor actuator.

14. The engine system of claim 11, wherein the compressor is a main casing compressor, the adjustment amount for the actuator is a first amount when the compressor is adjusted from a normal position to a surge position, and the adjustment amount for the actuator is a second amount when the compressor is adjusted from the normal position to a choke position.

15. The engine system of claim 11, wherein the EGR passage includes a low pressure EGR passage and a high pressure EGR passage, and adjusting the EGR flow further includes distributing EGR flow between the low pressure EGR passage and the high pressure EGR passage. ​

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