Turbocharger arrangement and series of feedback for the control of an electric actuator

Abstract

Procedures, encompassing the following: Adjusting a bypass valve actuator (150) coupled to a bypass valve (26) in an engine exhaust system (48) to control the boost pressure of an engine (10), wherein the adjustment based on a magnetic field of a magnet in the bypass valve actuator (150) is corrected based on a magnet temperature, characterized in that the setting includes adjusting a current applied to the actuator (150), wherein the setting is further based on a winding resistance of the motor (10), the resistance being based on the magnet temperature, and where the magnet temperature is estimated based on exhaust gas temperature and operating conditions.

Description

[0001] The invention relates to a method for controlling a turbocharger arrangement of an internal combustion engine and an electrical actuator.

[0002] Engines can use a turbocharger to improve the engine speed / power output density. For example, a turbocharger might include a compressor and a turbine connected by a drive shaft, with the turbine coupled to one side of the exhaust manifold and the compressor to the other side of the intake manifold. In this way, the exhaust-driven turbine supplies energy to the compressor to increase the pressure in the intake manifold (e.g., boost pressure) and increase the flow of air into the engine. The boost pressure can be controlled by adjusting the amount of gas reaching the turbine, for example, with a bypass valve. The bypass valve can be controlled based on operating conditions to achieve the desired boost pressure. In one example, the bypass valve could be an electronic bypass valve controlled by an associated electrical actuator.In some embodiments, the electric actuator is an electric motor. The electric motor is operated to change the position of the bypass valve, thereby controlling the amount of gas reaching the turbine and achieving the desired boost pressure.

[0003] US patent application US 2012 / 0001111A1 describes a set of feedback mechanisms for the position control of an exhaust valve using an electric actuator. The electric actuator includes an electric motor that transmits a driving force to a rod. The linear movement of the rod is then transmitted via rotary motion to a bypass valve, thereby controlling the bypass valve and thus the boost pressure supplied to the engine. An engine control unit senses the linear position of the rod using a stroke sensor that incorporates a magnetically sensing Hall element designed to detect changes in magnetic flux within a magnetic moving body contained in the electric actuator.Since there is a known correlation between the movement of the rod, the movement of the magnetic moving body, and the movement of the exhaust valve, the position of the exhaust valve can be monitored and controlled by sensing changes in the magnetic flux of the moving body. Furthermore, the stroke sensor can detect the rotational position of a lever in the actuator, which rotates to move the rod linearly.

[0004] US Patent 2012 / 0001111A1 discloses a control unit for a bypass valve comprising an electrical actuator with a magnetically movable body, wherein the magnetic field of the magnets is measured. US Patent 5,771,884A relates to a magnetic valve for patient ventilators with temperature compensation.

[0005] The inventors of the present invention recognized a problem with such approaches of using an electric actuator to control a bypass valve. Even if precise sensing is provided by controlling the magnetic flux, the torque provided by the electric actuator can fluctuate based on changes in the magnetic field generated in the actuator, caused by fluctuations in operating temperatures (which may exceed 100 °C). Without the ability to account for fluctuations in such a magnetic field, which varies across the operating temperature range, and their effects on the torque and position of the actuator, the control of the bypass valve can deteriorate, causing undesirable changes in boost pressure and engine power.Methods are provided for compensating the magnetic field of an electrical actuator that is functionally coupled to a bypass valve over a range of temperatures.

[0006] In one example, a bypass valve actuator coupled to a bypass valve in an engine exhaust line is adjusted to control the engine boost pressure. The adjustment is based on the magnetic field of a magnet in the bypass valve actuator and corrected based on the magnet's temperature.

[0007] In this way, by adjusting the bypass valve actuator based on a magnetic field and by correcting the setting based on a magnet temperature, it is possible to take into account fluctuations in the magnetic field due to temperature fluctuations and thereby to control the actuator torque, speed and bypass valve position more accurately.

[0008] According to the invention, the problem is solved by a method according to claim 1, 5 or 11.

[0009] In another example, a sensor can be used to measure the position of the actuator and calculate an angular velocity based on this position. A terminal voltage can then be measured and used together with the angular velocity to estimate the magnet temperature and magnetic field. For a given applied current and operating temperature, the actual torque of the actuator can then be estimated. In a further embodiment, an actuator resistance is estimated using an applied current, a terminal voltage, and a brush voltage. Based on the change in winding resistance per degree, a magnet temperature can then be estimated. The magnetic field can then be estimated. In this way, the magnetic field generated by an electric actuator can be estimated over a range of operating temperatures.The output of the electric actuator can be precisely controlled, which in turn controls the bypass valve and supplies the engine with the desired boost pressure. The present embodiments can apply a magnetic correction to the voltage or signal used to control the electric actuator. At a first temperature, where the magnitude of the magnetic field may be reduced, the magnetic correction can increase the actuation voltage or signal amplitude for a given desired actuator torque. At a second, lower temperature, where the magnitude of the magnetic field may be increased relative to that at the first temperature, the magnetic correction can decrease the actuation voltage or signal amplitude to provide the given desired actuator torque.

[0010] The advantages and features of the present invention mentioned above, as well as further advantages and features, will be readily apparent from the following detailed description, whether considered alone or in conjunction with the accompanying drawings.

[0011] It is understood that the foregoing summary is provided to present, in simplified form, a selection of concepts that are described in greater detail in the full description. It is not intended to identify key or essential features of the claimed subject matter, the scope of protection of which is clearly defined by the claims that follow the full description. Furthermore, the claimed subject matter is not limited to implementations that overcome the disadvantages mentioned above or in any part of this disclosure. Fig. Figure 1 shows a block diagram of a turbocharged engine that includes a bypass valve. Fig. Figure 2 shows a flowchart illustrating a method for controlling a turbocharger using a bypass valve. Fig. Figure 3 shows a flowchart illustrating a method for controlling a bypass valve using an electrical actuator. Fig. Figure 4 shows a flowchart illustrating a procedure for estimating and correcting a fluctuating magnetic field generated by an electrical actuator. Fig. Figure 5 shows a flowchart illustrating an alternative method for estimating and correcting a fluctuating magnetic field generated by an electrical actuator.

[0012] In forced-air engines, electronic bypass valve actuators can provide precise output to achieve a desired boost pressure. However, such actuators struggle with high ambient temperatures and large temperature fluctuations. The output of an electronic actuator can be a function of the current applied to it and the magnetic field generated by its magnets, if present. This magnetic field, including its magnitude, fluctuates as the ambient temperature changes over a range of operating temperatures that can exceed 100°C. Without the ability to account for variations in its magnetic field across the operating temperature range, the bypass valve control can degrade, causing undesirable changes in the forced-air engine's performance.Although the force generated by an electrical actuator can be a function of its magnetic flux multiplied by the current flowing through its windings (hereafter referred to as the "winding current"), it is understood that the magnetic flux can also be a function of the temperature of its magnets, which is based on the material composition of the magnets. The present disclosure assumes that the magnetic flux of an electrical actuator changes inversely proportional to the magnet temperature. However, the methods described herein can be adapted to the case in which the magnetic flux changes proportionally to the magnet temperature.

[0013] Several methods are provided for estimating and correcting a changing magnetic field in an electrical actuator. These methods can involve estimating the magnetic field based on multiple parameters, including angular velocity, terminal voltage, actuator current, and magnet temperature. Alternatively, they can involve estimating the magnetic field using a lookup table based on parameters such as electric current, brush voltage, and winding resistance. Fig. Figure 1 is a block diagram of a turbocharged engine that includes a bypass valve. The engine is from Fig. 1 also includes a controller configured to handle the in Fig. to carry out the procedures shown in points 2 to 5.

[0014] Fig. Figure 1 is a schematic diagram showing an exemplary engine 10 that may be included in a motor vehicle drive system. The engine 10 is shown with four cylinders 30. However, a different number of cylinders can be used with the present invention. The engine 10 can be controlled, at least partially, by a control system that includes a controller 12 and by inputs from a vehicle operator 132 via an input device 130. In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a pedal position proportional signal PP. Each combustion chamber (e.g., cylinder) 30 of the engine 10 can include combustion chamber walls with a piston (not shown) positioned therein. The pistons can be coupled to a crankshaft 40 such that the reciprocating motion of the piston is converted into a rotary motion of the crankshaft.The crankshaft 40 can be coupled to at least one drive wheel of the vehicle via an intermediate gear system (not shown). Furthermore, a starter motor can be coupled to the crankshaft 40 via a flywheel to enable the starting process of the engine 10.

[0015] The combustion chambers 30 can receive intake air from the intake manifold 44 via an intake air duct 42 and can discharge exhaust gases via an exhaust manifold 48. The intake manifold 44 and exhaust manifold 46 can be selectively connected to the combustion chamber 30 via corresponding intake valves and exhaust valves (not shown). In some embodiments, the combustion chamber 30 can include two or more intake valves and / or two or more exhaust valves.

[0016] Fuel injectors 50 are shown, which are directly connected to the combustion chamber 30 to inject fuel directly into the chamber in proportion to the pulse width of the FPW signal received by controller 12. In this way, the fuel injector 50 represents what is known as direct injection of fuel into the combustion chamber 30. The fuel injector can be mounted, for example, laterally or on top of the combustion chamber. Fuel can be supplied to the fuel injector 50 by a fuel system (not shown) that includes a fuel tank, a fuel pump, and a fuel rail.In some embodiments, the combustion chambers 30 may alternatively or additionally include a fuel injector arranged in the intake manifold 44 in a configuration that provides what is known as port fuel injection into the intake port upstream of each combustion chamber 30.

[0017] The intake air duct 42 can include throttle valves 21 and 23 with a throttle valve 22 and 24, respectively. In this particular embodiment, the position of the throttle valves 22 and 24 can be changed by the controller 12 using signals provided to an actuator contained in the throttle valves 21 and 23. In one example, the actuators can be electrical actuators (e.g., electric motors), and this configuration is commonly referred to as electronic throttle control. In this way, the throttle valves 21 and 23 can be actuated to vary the intake air supplied to a combustion chamber 30 among other engine cylinders. The position of the throttle valves 22 and 24 can be provided to the controller 12 by a throttle valve position signal TP.The intake air duct 42 can also include an air mass sensor 120 and an intake manifold pressure sensor 122 to provide the controller 12 with the corresponding signals MAF (air mass) and MAP (intake manifold absolute pressure).

[0018] The exhaust gas duct 48 can receive exhaust gas from the cylinders 30. The exhaust gas sensor 128 shown is coupled to the exhaust gas duct 48 upstream of the turbine 62 and an emission control device 78. The sensor 128 can be selected from various suitable sensors to provide an indication of the air-fuel ratio in the exhaust gas, such as a linear oxygen sensor or a UEGO (Universal Exhaust Gas Oxygen) sensor (wideband lambda sensor), an EGO (Exhaust Gas Oxygen) sensor (lambda sensor), a NOx, HC, or CO sensor. The emission control device 78 can be a three-way catalytic converter, a NOx separator, various other emission control devices, or a combination thereof.

[0019] The exhaust gas temperature can be measured by one or more temperature sensors (not shown) arranged in the exhaust gas duct 48. Alternatively, the exhaust gas temperature can be derived based on the engine operating conditions, such as engine speed, load, air-fuel ratio (AFR), ignition delay, etc.

[0020] The Controller 12 is in Fig. 1 shown as a microprocessor comprising a microprocessor unit 102, input / output connectors 104, an electronic storage medium for executable programs and calibration values, shown in this particular example as a read-only chip 106, a random access memory (RAM) 108, a battery-powered memory (KAM) 110 and a data bus.In addition to the signals already described, the controller 12 can receive various signals from sensors coupled to the engine 10, including the intake air mass (MAF) from the mass airflow sensor 120, the engine coolant temperature (ECT) from the temperature sensor 112, which is schematically shown at a location in the engine 10, an ignition profile recording signal (PIP) from a Hall effect sensor 118 (or other type) coupled to the crankshaft 40, the throttle position (TP) from a throttle position sensor as described, and the manifold absolute pressure (MAP) signal from sensor 122 as described. The engine speed signal (RPM) can be generated by the controller 12 from the PIP signal. The manifold pressure (MAP) signal from a manifold absolute pressure sensor can be used to provide a reading of vacuum or pressure in the intake manifold 44.It should be noted that various combinations of the aforementioned sensors can be used, such as a MAF sensor without a MAP sensor, or vice versa. During stoichiometric operation, the MAP sensor can provide an indication of the engine torque. Furthermore, this sensor, together with the detected engine speed, can provide an estimate of the charge (including air) drawn into the cylinder. In one example, the sensor 118, which is also used as an engine speed sensor, can generate a fixed number of evenly spaced pulses with each revolution of the crankshaft 40. In some examples, the read-only storage medium 106 can be programmed with computer-readable data embodying instructions executable by the processor 102 to perform the procedures described below, as well as other variations that are provided for but not specifically mentioned.

[0021] The engine 10 may further include a compression device, such as a turbocharger or pre-compressor, which includes at least one compressor 60 arranged along the intake manifold 44. In the case of a turbocharger, the compressor 60 may be driven at least partially by a turbine 62, for example via a shaft or other coupling arrangement. The turbine 62 may be arranged along the exhaust manifold 48. Various arrangements may be provided for driving the compressor. In the case of a pre-compressor, the compressor 60 may be driven at least partially by the engine and / or an electric machine and may not include a turbine. Thus, the degree of compression provided by a turbocharger or pre-compressor for one or more cylinders of the engine can be varied by the controller 12.In some cases, the turbine 62 can, for example, drive an electric generator 64 to supply energy to a battery 66 via a turbo drive 68. Energy from the battery 66 can then be used to drive the compressor 60 via a motor 70. Furthermore, a sensor 123 can be provided in the intake manifold 44 to supply a BOOST signal to the controller 12.

[0022] Furthermore, the exhaust gas duct 48 can include a bypass valve 26 to divert exhaust gas away from the turbine 62. In some embodiments, the bypass valve 26 can be a multi-stage bypass valve, such as a two-stage bypass valve with a first stage designed to control the boost pressure and a second stage designed to increase the heat flow to the emission control device 78. The bypass valve 26 can be actuated by an actuator 150, which can be, for example, an electric actuator containing permanent magnets. In some embodiments, the actuator 150 can be an electric motor. Further details regarding the bypass valve 26 and the actuator 150 are described below. The intake air duct 42 can include a compressor bypass valve 27 designed to divert intake air around the compressor 60.The bypass valve 26 and / or the compressor bypass valve 27 can be controlled by the controller 12 by means of actuators (e.g. actuator 150) to be opened, for example, when a lower boost pressure is desired.

[0023] The intake air duct 42 can further include a charge air cooler 80 (e.g., an intercooler) to reduce the temperature of the turbocharged or pre-compressed intake gases. In some embodiments, the charge air cooler 80 can be an air-to-air heat exchanger. In other embodiments, the charge air cooler 80 can be an air-to-liquid heat exchanger.

[0024] Furthermore, in the disclosed embodiments, an exhaust gas recirculation (EGR) system can direct a desired portion of the exhaust gas from the exhaust manifold 48 via an EGR manifold 140 to the intake air manifold 42. The amount of exhaust gas recirculated into the intake air manifold 42 can be varied by the controller 12 via an EGR valve 142. An EGR sensor (not shown) can also be arranged in the EGR manifold and provide a reading of pressure and / or temperature and / or exhaust gas concentration. Alternatively, the EGR can be controlled by a calculated value based on signals from the MAF sensor (upstream), MAP (intake manifold), MAT (manifold gas temperature), and crankshaft speed sensor. The EGR can also be controlled based on an exhaust gas oxygen sensor and / or an intake oxygen sensor (intake manifold).Under certain conditions, the EGR system can be used to regulate the temperature of the air-fuel mixture in the combustion chamber. Fig. Figure 1 shows a high-pressure EGR system in which the exhaust gas is routed from the upstream side of a turbocharger turbine to the downstream side of a turbocharger compressor. In other embodiments, the engine may additionally or alternatively include a low-pressure EGR system in which the exhaust gas is routed from the downstream side of a turbocharger turbine to the upstream side of a turbocharger compressor.

[0025] Now to Fig. 2. A motor controller (e.g., controller 12) can execute a method 201 for controlling a turbocharger via a bypass valve (e.g., bypass valve 26). For example, a method for controlling an engine's turbocharger via a bypass valve can include determining a desired boost pressure and an actual boost pressure. The bypass valve can be adjusted according to the difference between the desired boost pressure and the actual boost pressure.

[0026] Continue with Fig. 2. At 210, the procedure involves determining a desired boost pressure according to the engine operating conditions. The conditions to be evaluated can be measured directly with sensors, such as sensors 112, 118, 120, 122, 123, and 134, and / or can be estimated from other engine operating conditions. The conditions to be evaluated may include engine coolant temperature, engine oil temperature, mass airflow (MAF), manifold absolute pressure (MAP), boost pressure (for example, boost pressure from sensor 123), engine speed, idle speed, barometric pressure, driver-dependent torque (for example, from a pedal position sensor 134), ambient air temperature, vehicle speed, etc.

[0027] Next, the actual boost pressure can be determined at 220. The actual boost pressure can be measured directly by a sensor, such as sensor 123. The measured value can be sent directly to controller 12 via the BOOST signal and stored in a computer-readable memory medium. In an alternative embodiment, the actual boost pressure can be estimated based on other operating parameters, such as MAP and engine speed.

[0028] Next, the air pressure can be determined at 230. The air pressure can be measured, for example, by the MAP sensor when the engine is started and / or estimated based on engine operating conditions, including MAF, MAP, throttle position, etc. The measured value can be sent to the controller 12 and stored in a computer-readable memory medium. In an alternative embodiment, the air pressure can be estimated based on other operating parameters.

[0029] Next, at 240, the bypass valve actuation force can be calculated based on a pressure differential across the bypass valve, the exhaust flow, and / or the bypass valve angle. The bypass valve can then be adjusted according to this actuation force. The actuation force can correspond exactly to a pressure differential across the bypass valve. For example, the actuation force can be used as input to a bypass valve dynamic control system. This system can map a desired bypass valve pressure or position relative to a bypass valve duty cycle at a given actuation force. The controller generates the duty cycle signal and sends it to the bypass valve actuator to adjust the actuation force.Mapping the bypass valve's duty cycle can involve using lookup tables or calculating the duty cycle. A bypass valve control signal can include pulse width modulation using the bypass valve's duty cycle to adjust the bypass valve. The desired bypass valve pressure or position can be achieved, for example, through a feedback, positive feedback, or other control algorithm.

[0030] A compensation expression can account for delays in the bypass valve actuator. Additionally, the compensation expression can further include settings based on the movement of independent twin camshafts that can influence boost pressure. For example, the magnitude of the compensation expression can be decreased if the intake cam is moved in a way that increases boost pressure relative to atmospheric pressure. Similarly, the magnitude of the compensation expression can be increased if the intake cam is moved in a way that decreases boost pressure relative to atmospheric pressure.

[0031] Next, at 250, the bypass valve can be adjusted according to the desired boost pressure. For example, the desired boost pressure can be used as input to a pilot control algorithm to set the bypass valve position. The pilot control algorithm can process a target bypass valve pressure or a target bypass valve position, which can then be used as input to internal control circuits.

[0032] Next, at 260, a boost pressure deviation can be calculated as the difference between the desired boost pressure and the actual boost pressure. The bypass valve can be adjusted according to the processed boost pressure deviation. For example, the boost pressure deviation can be used as input to a feedback control algorithm to calculate a target bypass valve pressure when pressure control is desired, or a target bypass valve position within an inner control loop. The control algorithm can include a compensation expression as described above.

[0033] As described above, a bypass valve (e.g., bypass valve 26 in Fig. 1) operated by an actuator (e.g., actuator 150). The bypass valve can be adjusted to maintain a desired boost pressure level in an intake manifold of the engine. In some embodiments, the actuator can be an electric motor. Fig. Section 3 provides additional details of the operations performed at 260 when applied to an electric motor used to actuate a bypass valve. For example, procedure 301 can be executed by a motor controller (such as controller 12). Specifically, procedure 301 actuates a bypass valve and can further accommodate the fluctuation of a magnetic field generated by the electric motor, where the magnetic field varies as a function of the changing ambient temperature.

[0034] In procedure 301, step 310 determines the position of the motor. First, a measurement is taken, the type of which depends on the specific type of motor used. In one example, a sensor is made available and used to measure the linear displacement of a rod actuated by the motor. Alternatively, the motor may include a rotary encoder located inside the motor. The encoder may be coupled to the slowest rotating element in the motor, which is connected to an actuating rod. Such an encoder can collect readings over the entire range of rotation of the element, which may include, for example, 180 degrees. In this case, the encoder output varies with the rotation of the motor. In another example, the motor includes a spindle (e.g., a ball screw) whose rotation can be measured and used to determine the position of the bypass valve.However, a position sensor other than a ball screw can be used, or another rotating element can rotate over a range of more than 180 and / or 360 degrees. Various suitable sensors can be used that, for example, detect changes in angular position as opposed to changes in absolute position.

[0035] Next, at 320, the voltage drop across the motor terminals is measured or determined by other means. In one example, a probe wire is used to send a signal to an analog-to-digital converter to determine the terminal voltage supplied to a motor controller (e.g., the controller 12 in Fig. 1) is transmitted. Alternatively, the terminal voltage can be estimated based on the current drawn by the motor, if this quantity is known or can be measured, or by determining the difference between the voltage applied to the actuator and the back EMF generated by the actuator. Voltage estimates can also take into account losses due to conductive wires and other conductive components.

[0036] Next, the electrical current drawn by the motor is determined at 330. This can be determined, for example, by using a current probe or current sensor. Alternatively, the current can be calculated based on Ohm's law as the ratio of the actuator voltage (e.g., terminal voltage) to the actuator resistance, if these two values ​​are known or can be measured and if a resistance-temperature lookup table is available.

[0037] Next, flow forces acting on the bypass valve (e.g., bypass valve 26 in) are determined at 340. Fig. 1) act. In one example, the flow forces are determined based on a model. Alternatively, a pressure difference at the bypass valve is calculated and used to determine the flow forces. In another example, a lookup table is generated using inputs that include a bypass valve position to determine the flow forces. Such methods can utilize one or more sensors or sensor signals arranged in the engine 200, including the mass airflow sensor 120, the manifold absolute pressure sensor 122, the throttle position signal TP, BOOST from sensor 123, and a turbocharger rotational speed signal, and can optionally utilize one or more load sensors.

[0038] Next, a magnetic field correction expression is determined at 350. Exemplary methods used to determine the magnetic field are described in detail below, particularly with regard to Fig. 4 and Fig. 5. In this way, the motor can be operated precisely and the application of a suitable boost pressure can be ensured by taking into account the fluctuation of the magnetic field generated by the magnets contained in the motor when the temperature fluctuates within the operating temperature range.

[0039] If the ambient temperature rises, or if the initial temperature is relatively high, the magnetic field may be inhibited and its magnitude reduced. Consequently, the torque achieved by the motor at a given current also decreases. Such a torque loss can be compensated for by increasing the voltage, signal amplitude, and / or duty cycle used to drive the motor if greater torque is required to adequately actuate a bypass valve. Conversely, if the ambient temperature falls, or if the initial temperature is lower than the first, the magnetic field magnitude may be greater. The torque achieved by the motor at a given current is thus increased.Consequently, the voltage, signal amplitude, and / or duty cycle used to actuate the motor can be reduced, as less torque is required to adequately actuate the bypass valve. Various methods can utilize one or more threshold values, such that if the ambient temperature exceeds a threshold, the voltage or signal amplitude is increased, and conversely, if the temperature falls below the threshold, it is decreased. In some embodiments, the ambient temperature is approximated by determining the temperature of the motor magnets. As described above, the magnetic flux generated by the motor magnets can be a function of their temperature and may be proportional or inversely proportional depending on their material composition. It is assumed that the magnetic flux of an electrical actuator varies inversely proportional to its temperature.However, the methods described here can easily be adapted to the case in which the magnetic flux varies proportionally to the magnetic temperature.

[0040] In one example, the magnetic field is determined based on the well-known equation F = BIL for the case where the current flows perpendicular to the magnetic field. First, the current I supplied to the motor can be determined using various suitable methods, including those described above. The force F exerted by the motor can also be measured or determined using various suitable methods. The length L of the current-carrying wire can be pre-calculated based on known attributes of the motor. With these values, the magnetic field B generated by the motor can be calculated and used to determine a magnetic field correction when actuating a bypass valve. Certain quantities, such as the motor force, may not be available or may not be easily determined.In such a case, other methods may be suitable for determining the magnetic field of the motor, including those discussed below with reference to . Fig. 4 and Fig. 5 are described.

[0041] Finally, at 360 degrees, a voltage is applied to the motor, incorporating the magnetic field correction signal. This actuates the bypass valve and supplies the motor with the appropriate boost pressure. For example, a pulse-width modulated signal can be used to actuate the bypass valve. In one example, the duty cycle is increased as the temperature rises.

[0042] In this way, a bypass valve can be precisely controlled, ensuring that the desired boost pressure is provided to the engine while still responding to operating conditions and driver demands. Furthermore, by adjusting a bypass valve actuator based on a magnetic field and correcting the setting based on the magnet's temperature, it is possible to compensate for fluctuations in the magnetic field due to temperature variations, thereby controlling the actuator torque and thus the bypass valve position more precisely.

[0043] Now to Fig. 4. An exemplary method 401 is shown, which provides further details of the processes carried out at 350. In particular, method 401 indirectly determines the magnetic field generated by the motor magnets.

[0044] Method 401 begins at 410, where the position of the motor is determined. As described above, the motor may include a position sensor from which the motor position can be derived, although another suitable method for determining the motor position may also be used without deviating from the scope of protection of this disclosure.

[0045] Next, the angular velocity of the motor is determined at 420. Various suitable methods can be used to determine the angular velocity without deviating from the scope of protection of this disclosure. In the example of a position encoder, the angular velocity of the motor can be calculated by dividing the obtained angular position by a corresponding time interval. An instantaneous angular velocity can be calculated, or alternatively, the angular velocity can be time-averaged from several data points or filtered out in another way.

[0046] Next, the terminal voltage applied to the motor brushes at 430 is determined as described above. The terminal voltage can aid in estimating the motor's magnetic field, since it can be approximately proportional to the time derivative of Φ (the magnetic flux of the motor magnets) and the motor's angular velocity. Furthermore, the motor's magnetic field can be approximately determined by multiplying Φ by the area of ​​the motor poles.

[0047] Next, at output 440, a lookup table is generated using the motor angular velocity and terminal voltage, which are provided as inputs. Then, at output 450, the lookup table generated at output 440 outputs and estimates the temperature of the motor magnets, the motor angular velocity, and the motor magnetic field.

[0048] Finally, at 460, the actual motor torque for a given current at the current motor operating temperature can be estimated. This motor torque can then be provided to the motor position controller to improve the precise control of the motor position and thus the bypass valve position control.

[0049] Fig. Figure 5 shows an alternative method 501 for performing step 350 of method 301. In particular, method 501 measures a temperature near the motor magnets and uses this measurement to estimate the magnetic field generated by the motor.

[0050] In step 510 of procedure 501, the winding resistance of the motor is calculated based on the following ratio: V=I2R+K(dϕ / dt)+VBru¨rste, where V is the terminal voltage, I is the motor current, and R is the winding resistance. K is a constant, Φ the magnetic flux, t the time, and V Bürstethe voltage drop across the brush. In some embodiments, V Bürste 0.7 V per brush, although this information can be obtained from a prior test of the motor or from the motor specifications. In the case where the motor is not running, the flux expression can be omitted and the ratio reduces to V=I2R+VBru¨rste.

[0051] After the above-mentioned quantities have been determined, R is obtained and the winding resistance is estimated.

[0052] At 520, the magnet temperature is estimated under the assumption that the resistance of the windings varies as a function of temperature. For example, the resistance of copper changes by 0.4% per degree Celsius, although the ratio R=Ri(1+α(ΔT)) can be used to determine how the winding resistance changes with temperature, where R is the winding resistance, Ri Let α be the winding resistance at an initial temperature, α a specific coefficient of thermal expansion for the winding material, and ΔT a temperature change. Using a specific percentage change in resistance per degree and the calculated winding resistance, the winding temperature is estimated. Since the motor windings are located very close to the motor magnets, in one example, the magnet temperature can be estimated using the wire temperature.

[0053] At 530, a lookup table is generated and used to estimate the motor magnetic field.

[0054] In this way, undesirable turbocharger and engine operation resulting from degraded bypass valve control, caused by fluctuations in the bypass valve actuator's magnetic field as a function of temperature, can be reduced and / or prevented. At rising ambient temperatures or at a relatively high initial temperature, the magnetic field may be inhibited and its magnitude reduced. Consequently, the torque produced by the engine at a given current also decreases. Such a torque loss can be compensated for by increasing the voltage, signal amplitude, and / or duty cycle used to actuate the engine, as greater torque is required to adequately actuate a bypass valve. Conversely, if ambient temperatures decrease or at a second temperature lower than the first, the magnetic field magnitude may be greater.The torque achieved by the motor at a given current can therefore be increased. Consequently, the voltage, signal amplitude, and / or duty cycle used to actuate the motor can be reduced, as less torque is required to adequately actuate the bypass valve.

[0055] It should be noted that the exemplary control and estimation methods presented here can be used with various engine and / or vehicle system configurations. The specific methods described here can embody one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-process (multitasking), multi-threaded, and the like. Thus, various processes, operations, or functions shown can be executed in the sequence presented, in parallel, or, in some cases, omitted. Likewise, the processing sequence is not necessarily required to achieve the features and benefits of the exemplary embodiments described here; rather, it is provided to facilitate presentation and description.Depending on the specific strategy used, one or more of the described processes or functions can be executed repeatedly. Furthermore, the described processes can graphically represent a code that is to be programmed into the computer-readable storage medium in the engine control system.

[0056] It is understood that the designs and methods disclosed herein are exemplary and that these specific embodiments are not to be understood in a limiting sense, as numerous variations are possible. The technology described above can be applied to V6, I4, I6, V12, boxer, and other types of engines. The subject matter of the present invention includes all new and non-obvious combinations and sub-combinations of the various systems and designs, as well as further features, functions, and / or properties disclosed herein.

[0057] The following claims specifically identify certain combinations and subcombinations that are considered novel and not obvious. The claims may name "one" element, "a first" element, or an equivalent thereof. Such claims are to be understood as including one or more such elements and neither requiring nor excluding two or more such elements. Further combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or related applications. These claims, whether broader, more limited, the same, or different in scope of protection compared to the original claims, are also to be considered as included in the subject matter of the present disclosure.

Claims

[1] Procedure, comprising the following: Adjusting a bypass valve actuator (150) coupled to a bypass valve (26) in an engine exhaust system (48) to control the boost pressure of an engine (10), wherein the adjustment based on a magnetic field of a magnet in the bypass valve actuator (150) is corrected based on a magnet temperature, characterized in that the setting includes adjusting a current applied to the actuator (150), wherein the setting is further based on a winding resistance of the motor (10), the resistance being based on the magnet temperature, and where the magnet temperature is estimated based on exhaust gas temperature and operating conditions. [2] Method according to claim 1, wherein the setting further comprises: for a first material, reducing the current for a given actuator torque when the magnet temperature is above a limit value, and increasing the current for the given torque when the magnet temperature is below a limit value, and for a second material, increasing the current for a given actuator torque when the magnet temperature is above a limit value, and reducing the current for the given torque when the magnet temperature is below a limit value. [3] Method according to claim 2, wherein the magnetic field is estimated based on a lookup table which has inputs that include an actuator position, an actuator angular velocity and a terminal voltage. [4] Method according to claim 2, wherein the magnetic field is estimated based on a lookup table, wherein the lookup table is generated based on one or more of an actuator current, a terminal voltage, a brush voltage, an estimated wire resistance, a resistance change and an estimated wire temperature. [5] Method for controlling a turbocharger of an engine (10) by means of an electrical actuator (150), comprising the following: Estimating the magnetic temperature of one or more magnets arranged in the electrical actuator (150), Estimating the magnetic field of one or more magnets based on the estimated magnetic temperature, Determining a magnetic field correction based on the estimated magnetic field, actuating the electrical actuator (150) with a current determined based on the magnetic field correction, and Adjusting the magnetic field correction based on a change in the estimated magnetic temperature, characterized in that The setting includes adjusting a current applied to the actuator (150), wherein the setting is further based on a winding resistance of the motor (10), the resistance being calculated based on a motor current, a terminal voltage and a brush voltage drop. [6] Method according to claim 5, wherein the actuator (150) includes permanent magnets. [7] Method according to claim 6, wherein the actuator (150) is coupled to a bypass valve (26) of the turbocharger. [8] Method according to claim 7, wherein a position of the bypass valve (26) is controlled to a desired position based on the magnetic field correction. [9] Method according to claim 8, wherein the desired position is based on a desired level of engine boost pressure. [10] Method according to claim 9, further comprising direct injection of fuel into a cylinder (30) of the engine (10). [11] Method for controlling an engine turbocharger bypass valve (26) by means of an electrical actuator (150), comprising the following: at a first temperature: Adjustment of the electrical actuator (150) based on an enhanced magnetic field voltage correction and at a second, lower temperature: Adjustment of the electrical actuator (150) based on a reduced magnetic field voltage correction. [12] Method according to claim 11, wherein the electrical actuator (150) includes magnets. [13] Method according to claim 12, wherein the electrical actuator (150) is adjusted by setting a duty cycle provided for the electrical actuator (150) by a controller (12), wherein the controller (12) includes commands to perform the adjustment operations. [14] Method according to claim 13, wherein the bypass valve (26) is adjusted to maintain a desired boost pressure in an intake air duct (42) of the engine (10). [15] Method according to claim 13, wherein the duty cycle is increased at a first temperature and decreased at a second temperature.

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