Method and system for operating an electric turbocharger

Abstract

The present disclosure provides a method and system for operating an electric turbocharger. A system and method for operating an internal combustion engine including an electric turbocharger are described. The system and method can operate the electric turbocharger in a motor mode or a generator mode. The electric turbocharger can be operated in a generator mode to reduce the amount of time the electric turbocharger is activated in the motor mode.

Description

Technical Field

[0001] The present description relates to methods and systems for operating an electric turbocharger coupled to an internal combustion engine. The methods and systems may be used to reduce activation time of the electric turbocharger. Background Art

[0002] The vehicle may include an internal combustion engine for propelling the vehicle, and the engine may include a turbocharger for increasing the output of the engine. The turbocharger may be driven via exhaust to pressurize the air entering the engine, thereby increasing the capacity of the engine to generate electricity. The turbocharger may also include a motor for increasing the air flow to the engine when the engine exhaust flow is low. The motor may be powered by an inverter. The inverter converts direct current (DC) power into alternating current (AC) power so that the motor can generate torque to rotate the compressor of the turbocharger. The inverter may include a power filter capacitor, which must be charged to a threshold level before the motor can operate as a motor. The power filter capacitor may be powered by the vehicle system power supply via a power contactor. Due to diagnostics, system check functions, and other reasons at the time of engine start request, the vehicle system power supply may not be able to provide power to the power filter capacitor for a period of time. Therefore, the power contactor may be kept in an open state for a period of time before the power filter capacitor can be charged. Therefore, after the engine is started and running, the motor may not be able to provide torque to rotate the turbocharger compressor for a predetermined amount of time. Therefore, if the vehicle is started and the driver requests power just after the engine is started, engine performance may be lower than expected. Summary of the invention

[0003] The inventors herein have recognized the above-mentioned problems and have developed an engine operating method, which includes: receiving an input to a controller, the input indicating a request to start the engine; and operating an electric turbocharger in a generator mode via the controller and charging a power filter capacitor connected to a DC bus in response to the received input.

[0004] By operating the electric turbocharger in generator mode and charging a power filter capacitor coupled to the DC bus in response to an input to a controller indicating an engine start request, the following technical result can be provided, namely, the power filter capacitor is charged before the power contactor is closed, so that the electric turbocharger can be operated in motor mode earlier than when the power filter capacitor is charged only via the vehicle system power supply.

[0005] The present description may provide several advantages. Specifically, the method may reduce the amount of time between when the power contactor is closed and when the electric turbocharger may be operated in motor mode. Furthermore, the method may reduce the electrical load on the vehicle system power supply. Furthermore, the method may provide accurate charging control of the power filter capacitor.

[0006] The above advantages and other advantages and features of the present specification will become apparent when the following detailed description is considered alone or in conjunction with the accompanying drawings.

[0007] It should be understood that the above summary is provided to introduce in simplified form some concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The advantages described herein will be more fully understood by reading the examples of embodiments herein referred to as detailed description either alone or with reference to the accompanying drawings, in which:

[0009] Figure 1 is a schematic diagram of an internal combustion engine;

[0010] Figure 2 is a schematic diagram of the inverter and electrically driven turbocharger;

[0011] Figure 3 is based on Figure 4 An example engine operation sequence of the method of; and

[0012] Figure 4 A flow chart showing a method for operating an engine and an electrically driven turbocharger is shown. DETAILED DESCRIPTION

[0013] The present description relates to operating an engine including an electric turbocharger. The engine may be Figure 1 The electric turbocharger may be of the type shown, and it may include an electric turbocharger. The electric turbocharger may operate in a motor mode and a generator mode. The electric turbocharger may compress air entering the engine when it operates in the motor mode. The electric turbocharger may convert energy from the vehicle exhaust system into electricity when it operates in the generator mode. The electric turbocharger may be electrically coupled to an inverter, such as Figure 2 As shown in the figure, the electric turbocharger and the engine can be Figure 4 The method of Figure 3 Sequence operation.

[0014] refer to Figure 1The internal combustion engine 10 includes a plurality of cylinders. Figure 1 One of the cylinders is shown in FIG. 1 . The engine 10 is controlled by an electronic engine controller 12. The controller receives information from Figure 1 The various sensor signals (eg, input) and the use of Figure 1 Various actuators may be used to adjust engine operation based on received signals and instructions stored in the memory of controller 12. For example, fuel injection timing, spark timing, and poppet valve operation may be adjusted in response to engine position as determined from the output of an engine position sensor.

[0015] Engine 10 includes combustion chamber 30 and cylinder walls 32, with piston 36 positioned in the combustion chamber and connected to crankshaft 40. Starter motor 41 may rotate crankshaft 40 during engine starting. Combustion chamber 30 is shown communicating with intake manifold 44 and exhaust manifold 48 via respective intake poppet valve 52 and exhaust poppet valve 54. Each intake valve and exhaust valve may be operated by variable intake valve operator 51 and variable exhaust valve operator 53, which may be actuated mechanically, electrically, hydraulically, or by a combination thereof. Intake valve operator 51 and exhaust valve operator may open intake valve 52 and exhaust valve 54 synchronously or asynchronously with crankshaft 40. The position of intake valve 52 may be determined by intake valve position sensor 55. The position of exhaust valve 54 may be determined by exhaust valve position sensor 57.

[0016] Fuel injector 66 is shown positioned to inject fuel directly into cylinder 30, which is known to those skilled in the art as direct injection. Alternatively, fuel may be injected into an intake port, which is known to those skilled in the art as port injection. Fuel injector 66 delivers liquid fuel in proportion to the pulse width of the signal from controller 12. Fuel is delivered to fuel injector 66 by fuel system 175. In addition, intake manifold 44 is shown in communication with optional electronic throttle 62 (e.g., a butterfly valve), which adjusts the position of throttle plate 64 to control air flow from air filter 43 and air intake 42 to intake manifold 44. Throttle 62 regulates air flow from air filter 43 in engine air intake 42 and electric turbocharger 159 to intake manifold 44. In one example, a high pressure dual-stage fuel system may be used to generate higher fuel pressures. In some examples, throttle 62 and throttle plate 64 may be positioned between intake valve 52 and intake manifold 44 such that throttle 62 is a port throttle.

[0017] The electric turbocharger 159 includes a compressor 162 that can be rotated via a turbine 160 and a shaft 161. Thus, the turbine 160 is mechanically coupled to the compressor 162 via the shaft 161. The motor 143 is also coupled to the shaft 161, and when the motor is powered via the inverter 144, it can also rotate the compressor 162. The controller 12 can communicate with the inverter 144 via a controller area network (CAN) 145 or via an alternative communication path. The blades 163 of the compressor 162 can rotate to compress the air entering the engine 10. The speed of the compressor 162 can be adjusted via the motor 143 and / or the wastegate 165. The wastegate 165 can be opened via the controller 12 to allow exhaust to bypass the turbine 160 via the bypass passage 166. The electric turbocharger 140 can pump air from the intake 42 to the throttle 62 by increasing the speed of the blades 163. Controller 12 may increase and decrease the speed of vane 163 to increase and decrease the air pressure upstream and downstream of throttle 62. Controller 12 may increase compressor speed by increasing the current supplied to motor 143 and / or by closing wastegate 165. Controller 12 may decrease compressor speed by decreasing the current supplied to motor 143 and / or by opening wastegate 165.

[0018] Distributorless ignition system 88 provides an ignition spark to combustion chamber 30 via spark plug 92 in response to controller 12. Universal Exhaust Gas Oxygen (UEGO) sensor 126 is shown coupled to exhaust manifold 48 upstream of catalytic converter 70. Alternatively, a two-state exhaust gas oxygen sensor may be used in place of UEGO sensor 126.

[0019] In one example, converter 70 may include multiple catalyst bricks. In another example, multiple emission control devices may be used, each having multiple bricks. In one example, converter 70 may be a three-way type catalyst.

[0020] The controller 12 Figure 11 is shown as a conventional microcomputer including: a microprocessor unit (CPU) 102; input / output ports 104; read-only memory 106 (eg, non-transitory memory); random access memory (RAM) 108; keep alive memory (KAM) 110; and a conventional data bus. Controller 12 is shown receiving various signals in addition to those previously discussed from sensors coupled to engine 10, including: engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114; position sensor 134 coupled to accelerator pedal 130 for sensing force applied by human driver 132; measurement of engine manifold pressure (MAP) from pressure sensor 122 coupled to intake manifold 44; engine position sensor from Hall effect sensor 118 sensing position of crankshaft 40; measurement of air mass entering the engine from sensor 120; brake pedal position from brake pedal position sensor 154 when human driver 132 applies brake pedal 150; and measurement of throttle position from sensor 58. Barometric pressure may also be sensed (sensor not shown) for processing by controller 12. In a preferred aspect of the present description, engine position sensor 118 generates a predetermined number of equally spaced pulses per revolution of the crankshaft from which engine speed (RPM) may be determined. Controller 12 may also receive input from a human / machine interface 138 , which may be configured as a button, a key switch, or an interactive display panel.

[0021] In some examples, the engine can be coupled to an electric motor / battery system in a hybrid vehicle. Additionally, in some examples, other engine configurations can be employed, such as a diesel engine.

[0022] During operation, each cylinder within engine 10 typically undergoes a four-stroke cycle: the cycle includes an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. During the intake stroke, generally speaking, exhaust valve 54 is closed and intake valve 52 is opened. Air is introduced into combustion chamber 30 via intake manifold 44, and piston 36 moves to the bottom of the cylinder to increase the volume within combustion chamber 30. The position of piston 36 near the bottom of the cylinder and at the end of its stroke (e.g., when combustion chamber 30 is at its largest volume) is typically referred to by those of skill in the art as bottom dead center (BDC). During the compression stroke, intake valve 52 and exhaust valve 54 are closed. Piston 36 moves toward the cylinder head so as to compress the air within combustion chamber 30. The point at which piston 36 is at the end of its stroke and closest to the cylinder head (e.g., when combustion chamber 30 is at its smallest volume) is typically referred to by those of skill in the art as top dead center (TDC). In a process hereinafter referred to as injection, fuel is introduced into the combustion chamber. In a process hereinafter referred to as ignition, the injected fuel is ignited by known ignition means, such as spark plug 92, resulting in combustion. During the expansion stroke, the expanding gases push piston 36 back to BDC. Crankshaft 40 converts piston movement into rotational torque of the rotating shaft. Finally, during the exhaust stroke, exhaust valve 54 opens to release the combusted air-fuel mixture to exhaust manifold 48, and the piston returns to TDC. It should be noted that the above is shown only as an example, and the intake and exhaust valve opening and / or closing timings may be varied, such as to provide positive or negative valve overlap, late intake valve closing, or various other examples.

[0023] refer to Figure 2 , the inverter 144 is shown as being electrically coupled to the motor 143. The inverter can also be selectively electrically coupled to a vehicle system power supply 275 via a power contactor 235. The vehicle system power supply 275 can include one or more batteries and a power controller. In this example, the vehicle system power supply 275 includes a plurality of battery cells 233 that are connected in series to increase the voltage of the vehicle system power supply 275. The inverter 144 is also shown as being electrically coupled to the motor 140 (e.g., a three-phase motor that can operate as a motor or an alternator).

[0024] The inverter 144 includes a controller 202 that can communicate with the inverter via a controller area network (CAN) 145. Figure 1201. The controller 202 is electrically coupled to the bases of the transistors 206, 208, and 210-215. The controller 202 may provide control signals to independently activate and deactivate the transistors 206, 208, and 210-215. The controller 202 includes inputs and outputs 284 (e.g., digital inputs, digital outputs, analog inputs, analog outputs), a non-temporary memory 286 (e.g., a read-only memory or an electrically erasable memory), a central processing unit 282, and a temporary memory 288. The controller 202 may sense the voltage at the node 203 and sense the current through the inductor 204 via the current sensor 299. In addition, the controller 202 may sense the voltage of the power filter capacitor 231 at the node 201.

[0025] Transistors 206, 208, and 210-215 are shown as insulated gate bipolar transistors (IGBTs), but in alternative configurations, they may be metal oxide field effect transistors (MOSFETs), field effect transistors (FETs), or other known types of transistors. Controller 202 may activate the IGBTs by providing a higher potential voltage to the gates of transistors 206, 208, and 210-215. Controller 102 may deactivate the IGBTs by providing a lower potential voltage to the gates of transistors 206, 208, and 210-215. The gates of transistors 206 and 208 are represented by the letter "G". The collectors of transistors 206 and 208 are represented by the letter "C". The emitters of transistors 206 and 208 are represented by the letter "E". Transistors 210-215 have bases, emitters, and collectors similar to those shown in transistors 206 and 208. Transistors 206 and 208 also include diodes 207 and 209, which are forward biased between the respective emitters and collectors. When transistors 206 and 208 are activated, current can flow between their collectors and emitters. When transistors 206 and 208 are deactivated, current flow between the collectors and emitters of transistors 206 and 208 is blocked. Transistors 210-215 operate similarly, but these transistors form a three-phase transistor array. Transistors 210-215 can be selectively activated and deactivated to convert DC to AC and AC to DC.

[0026] Inductor 204 is shown as being directly electrically coupled to transistors 206 and 208. Inductor 204 is also directly electrically coupled to capacitors 250, 252. Inductor 204 may selectively be electrically coupled to a vehicle system power supply 275. The vehicle system power supply includes a controller 238 that may perform diagnostics, system checks, perform balancing operations, and communicate with the vehicle system. Figure 1 12 communicates with the controller 12 and operates the power contactor 235. Capacitor 251 is shown electrically coupled to the negative side of capacitor 250 and vehicle system power supply 275.

[0027] In boost mode, the controller 202 may selectively activate transistor 208 (which may be referred to as a boost transistor) to charge the inductor 204 with the charge provided by the vehicle system power supply 275 from the positive terminal 233a. The inductor 204 blocks current flow as it begins to store electrical energy in a magnetic field. When the boost transistor 208 is turned off, the polarity of the left hand side of the inductor 204 is positive. When the boost transistor 208 is turned on, the current through the inductor 204 decreases and the magnetic field of the inductor begins to collapse. The polarity of the inductor 204 changes so that the right side of the inductor 204 has a positive polarity because the collapsed magnetic field of the inductor supports continued current flow to the load. The voltage of the vehicle system power supply 275 and the voltage developed across the inductor 204 are connected in series, thereby providing the voltage of the vehicle system power supply 175 plus the voltage of the inductor 204 at node 280. The voltage at node 280 minus the small voltage drop across diode 207 is generated at node 201, which is the output of the variable voltage control inverter boost circuit and the input to transistors 210-215 when the variable voltage converter (VVC) 271 is operated in boost mode and the motor 143 is operated as a motor, because the diode 207 is forward biased. Charge can be stored in the power filter capacitor 231 to smooth the output voltage of the boost circuit at node 201. The power filter capacitor 231 can have a high storage capacity, which may take several seconds to tens of seconds to charge. The voltage at node 201 is a DC voltage along the length of the DC bus 285. The variable voltage control inverter boost circuit may include capacitors 250-252, an inductor 204, a boost transistor 208, a diode 209, and a diode 207. The voltage at node 201 is supplied to transistors 210-215, which are turned on and off to provide three-phase AC power to the motor 140. Whenever boost transistor 208 is commanded to be activated, buck transistor 206 is commanded to be deactivated to prevent a short circuit between node 201 and node 281. In some examples, VCC 271 may be omitted and vehicle system power 275 may be coupled directly to the three-phase inverter transistors.

[0028] If the motor 143 is requesting only a small amount of power, the vehicle system supply voltage minus the small voltage drop of the inductor 204 and the diode 207 may be supplied at the node 201 by deactivating the buck transistor 206 and the boost transistor 208 .

[0029] In buck mode, charge can be supplied to inductor 204 via motor 143. Specifically, the three-phase AC output of motor 143 can be converted to a DC voltage at node 201 by switching transistors 210-215 via controller 202. The DC voltage at node 201 can charge power filter capacitor 231. Inductor 204 can be charged via activation transistor 206, which can be referred to as a buck transistor. However, if motor 143 charges power filter capacitor 231 in response to engine starting, transistors 206 and 208 can remain off so that only power filter capacitor 231 is charged and capacitors 250, 251, and 252 are not charged. If transistor 206 is activated, inductor 204 blocks current flow when it begins to store electrical energy in a magnetic field. When boost transistor 206 is turned off, the polarity of the right-hand side of inductor 204 is positive. When the buck transistor 206 is turned on, the current through the inductor 204 decreases and the magnetic field of the inductor begins to collapse. The polarity of the inductor 204 changes so that the left side of the inductor 204 has a positive polarity because the collapsing magnetic field of the inductor supports continued current flow to the load (e.g., capacitors 250, 251, and 252). The amount of time that the inductor 204 is allowed to charge is controlled so that the voltage generated across the inductor 204 is less than the voltage output via the motor 143. The diode 209 connects the right side of the inductor 204 to the node 281, which is connected to the negative battery terminal 233b. The voltage generated across the inductor 204 is connected to the positive terminal 233a of the vehicle system power supply 275. The charge from the inductor 204 can flow to the capacitors 250, 251, and 252. The voltage at the node 203 is controlled by adjusting the amount of time that the buck transistor 206 is activated (e.g., turned off to allow current to flow through the transistor). Whenever the buck transistor 206 is activated, the boost transistor 208 is disabled (e.g., disconnected to prohibit current from flowing through the transistor). Charge can be stored in capacitors 250-252 to smooth the output voltage of the buck circuit at node 203. The voltage at node 203 is a DC voltage. The variable voltage controlled inverter buck circuit may include capacitors 250-252, an inductor 204, a buck transistor 206, a diode 209, a capacitor 231, and a resistor 230. The voltage at node 203 is the output voltage of the variable voltage controlled inverter buck circuit. The controller 202 may monitor the voltage at nodes 203 and 201. In addition, the controller 202 may adjust the duty cycle of the signal supplied to the boost transistor 208 and the buck transistor 206 in response to the voltage at nodes 203 and 201.

[0030] therefore, Figure 1 and Figure 2A system is provided, the system comprising: an engine; an electric turbocharger, which is coupled to the engine; an inverter, which is electrically coupled to the electric turbocharger, the inverter including a power filter capacitor coupled to a DC bus; a power contactor, which selectively couples a DC power source to the inverter; and a controller, which includes executable instructions stored in a non-transitory memory, for starting the engine and operating the electric turbocharger in a generator mode before the power contactor is closed to charge the power filter capacitor. The system includes a case where the inverter includes a three-phase transistor array. The system includes a case where the inverter includes a buck transistor and a boost transistor. The system also includes additional instructions for adjusting the position of the wastegate to control the output of the electric turbocharger when the electric turbocharger is operated in a generator mode. The system also includes additional instructions for adjusting the position of the wastegate to control the output of the electric turbocharger when the electric turbocharger is operated in a motor mode. The system also includes additional instructions for stopping the operation of the electric turbocharger in a generator mode in response to the voltage of the power filter capacitor.

[0031] Reference now Figure 3 , showing that according to Figure 4 The engine operation sequence of the method can be Figure 1 and Figure 2 system to execute Figure 3 The vertical lines at times t0-t9 represent times of interest during the sequence.

[0032] from Figure 3 The first graph at the top of FIG. 302 is a graph of vehicle operating conditions versus time. The vertical axis represents engine operating conditions. When trace 302 is at a lower level near the horizontal axis, the engine is off, not spinning, and not burning fuel. When trace 302 is at a higher level near the vertical axis arrow, the engine is on, spinning, and burning fuel. The horizontal axis represents time and the amount of time increases from the left side of the graph to the right side of the graph.

[0033] from Figure 3 The second graph at the top of FIG. 304 is a graph of engine start request status versus time. The vertical axis represents the engine start request status. When the trace 304 is at a lower level near the horizontal axis, the engine start request status is not asserted. When the trace 304 is at a higher level near the vertical axis arrow, the engine start request status is asserted. When the engine is on, the engine start request remains asserted. The horizontal axis represents time and the amount of time increases from the left side of the graph to the right side of the graph.

[0034] from Figure 3 The top third graph is the power contactor status (e.g., Figure 2235 shown) versus time. The vertical axis represents the power contactor state. When the trace 306 is at a lower level near the horizontal axis, the power contactor state is open (e.g., power is not conducted through the contactor). When the trace 306 is at a higher level near the vertical axis arrow, the contactor state is closed (e.g., power is conducted through the contactor). The horizontal axis represents time and the amount of time increases from the left side of the graph to the right side of the graph.

[0035] from Figure 3 The fourth graph from the top is a power filter capacitor (e.g. Figure 2 231) versus time. The vertical axis represents the power filter capacitor state of charge and the power filter capacitor state of charge increases in the direction of the vertical axis arrow. Horizontal line 350 represents the threshold power filter capacitor state of charge. The electric turbocharger may not operate in motor mode until the power filter capacitor state of charge is greater than the level of line 350. The horizontal axis represents time and the amount of time increases from the left side of the graph to the right side of the graph.

[0036] from Figure 3 The fifth graph from the top is a graph of inverter switching state versus time. The vertical axis represents the inverter switching state. When the trace 310 is at a lower level near the horizontal axis, the inverter switch is not switching. When the trace 310 is at a higher level near the vertical axis arrow, the inverter switch is switching. The horizontal axis represents time and the amount of time increases from the left side of the graph to the right side of the graph.

[0037] from Figure 3 The sixth graph at the top of is a graph of turbocharger operating mode versus time. The vertical axis represents the turbocharger operating mode. When the trace 312 is at a higher level along the vertical axis, marked as "motor", the turbocharger is operating as a motor. When the trace 312 is at a lower level along the vertical axis, marked as "generator", the turbocharger is operating as a generator. When the trace 312 is at an intermediate level along the vertical axis, marked as "off", the turbocharger is not operating (e.g., not consuming charge nor generating charge). The horizontal axis represents time and the amount of time increases from the left side of the graph to the right side of the graph.

[0038] At time t0, the engine is off and the engine start request is not asserted. The power contactor is open and the inverter switches (e.g., three-phase switching array switches 210-215) are not switching. The power filter state of charge is low and the turbocharger is off. Such conditions may indicate that the vehicle is not operating or that the vehicle is operating in a pure electric mode in which the vehicle is propelled only via an electric machine (not shown).

[0039] At time t1, an engine start request is asserted. The engine start request may be asserted via a human driver requesting an engine start or via a controller requesting an engine start. The engine is off, but it starts shortly after time t1. The power contactor remains open, and the power filter capacitor state of charge remains low. The inverter is not switching, and the turbocharger is off.

[0040] At time t2, the engine is running and the engine start request remains asserted. The turbocharger begins to operate as a generator, providing power to the inverter via exhaust gas from the engine that rotates the turbocharger. The inverter three-phase switch begins to switch, and the power filter capacitor state of charge begins to increase as power from the turbocharger is stored in the power filter capacitor. The power contactor remains open while the vehicle system power supply is performing a system check and cannot power the turbocharger.

[0041] Between time t2 and time t3, the engine continues to operate and the engine start request remains asserted. The power contactor remains open and the power filter capacitor state of charge continues to increase. The inverter three-phase switch continues to switch and the turbocharger continues to operate as a generator.

[0042] At time t3, the vehicle system power supply indicates that the power contactor is about to close (not shown), so inverter switching stops and the turbocharger state changes to off. The engine continues to run and the engine start request remains asserted. The power contactor remains closed and the power filter capacitor charge state stops increasing.

[0043] At time t4, the power contactor closes to allow power to flow from the vehicle system power supply to the inverter. The engine continues to run, and the engine start request remains asserted. The power capacitor state of charge begins to increase again, and the inverter does not switch because the power filter capacitor state of charge is less than the threshold value 350. The turbocharger remains in the off state.

[0044] Between time t4 and time t5, the power filter capacitor state of charge exceeds the threshold level 350, so the inverter begins switching, and the turbocharger begins operating in motor mode so that it can supply compressed air to the engine. The engine continues to run, and the engine start request remains asserted. The power filter capacitor state of charge remains above the threshold 350.

[0045] At time t5, the engine start request is not asserted, so the engine stops shortly thereafter. Because the engine is not running, and because there is no need to pressurize the air in the engine intake when the engine is not running, the power contactor opens. The inverter also stops switching, and the turbocharger enters the off mode.

[0046] Between time t5 and time t6, the power filter capacitor state of charge slowly decreases, which may be caused by parasitic losses in the inverter system. The power filter capacitor state of charge level drops below the threshold 350. The engine remains off and the engine start request is not asserted. The power contactor remains open and the inverter is not switching. The turbocharger also remains off.

[0047] At time t6, the engine start request is asserted. The engine is off, but it starts shortly after time t6. The power contactor remains open, and the power filter capacitor state of charge remains below threshold 350, but at a higher state of charge level than at time t1. The inverter three-phase switch does not switch, and the turbocharger is off.

[0048] At time t7, the engine is running and the engine start request remains asserted. The turbocharger begins to operate as a generator, providing power to the inverter via exhaust gas from the engine that rotates the turbocharger. The inverter three-phase switch begins switching, and the power filter capacitor state of charge begins to increase from an intermediate level as power from the turbocharger is stored in the power filter capacitor. The power contactor remains open while the vehicle system power supply is performing a system check and cannot power the turbocharger.

[0049] Between time t7 and time t8, the engine continues to operate and the engine start request remains asserted. The power contactor remains open and the power filter capacitor state of charge continues to increase. The power filter capacitor state of charge approaches threshold 350. The inverter three-phase switches continue to switch, and the turbocharger continues to operate as a generator.

[0050] At time t8, the power filter capacitor charge state exceeds the threshold 350, so the turbocharger is turned off and the inverter three-phase switch stops switching. The engine continues to run and the engine start request remains asserted. Shortly thereafter, the vehicle system power supply indicates that the power contactor is about to close (not shown), but because the inverter switch has stopped switching and because the turbocharger state has changed to off, no further action is taken.

[0051] At time t9, the power contactor closes to allow power to flow from the vehicle system power supply to the inverter. The engine continues to run, and the engine start request remains asserted. The power capacitor charge state remains high and the inverter three-phase switch begins to switch so that the turbocharger can supply compressed air to the engine. The turbocharger begins to operate in motor mode. After time t9, the engine continues to operate and the turbocharger supplies compressed air to the engine.

[0052] In this way, the amount of time the power filter capacitor takes to charge after the power relay is closed can be reduced so that the electric turbocharger can be used sooner after the engine is started. An activated electric turbocharger can improve engine performance.

[0053] Reference now Figure 4 , a method for operating an engine is shown. Figure 4 The method can be used as a storage Figure 1 and Figure 2 The executable instructions in the non-transitory memory of the system are included. In addition, Figure 4 The method can be used with Figure 1 and Figure 2 systems work together to receive data and adjust actuators to control the physical or real world Figure 1 and Figure 2 system.

[0054] At 402, method 400 determines engine operating conditions. Engine operating conditions may include, but are not limited to, engine speed, engine load, turbocharger mode, engine temperature, engine start request status, inverter power filter capacitor charge state, and power contactor charge state. Method 500 may be determined by Figure 1 The various sensors described in 400 determine engine operating conditions. Method 400 proceeds to 404 .

[0055] At 404, method 400 determines whether the engine is on (e.g., spinning and burning fuel). In one example, if the engine speed is non-zero and spark and fuel are supplied to the engine, method 400 can determine that the engine is on or running. If method 400 determines that the engine is on, then the answer is yes and method 400 proceeds to 420. Otherwise, the answer is no and the method proceeds to 406.

[0056] At 420, method 400 adjusts the speed of the electric turbocharger in response to the engine speed and the driver demand torque. The driver demand torque can be determined based on the accelerator pedal position, and the engine speed can be determined via an engine position sensor. In one example, method 400 adjusts the speed of the electric turbocharger to a predetermined speed, which is empirically determined and stored in a table or function in a controller memory. The table or function can be referenced or indexed via the engine speed and the driver demand torque. The value in the table can be determined by measuring the engine efficiency while adjusting the speed of the electric turbocharger, and the engine efficiency includes the efficiency of the electric turbocharger. The speed of the electric turbocharger can be adjusted by supplying a charge to the electric turbocharger, reducing the charge supplied to the electric turbocharger, or by adjusting the position of the wastegate. The method for adjusting the speed of the electric turbocharger may depend on the engine operating conditions. Method 400 adjusts the speed of the electric turbocharger and moves forward to exit.

[0057] At 406, method 400 determines whether an engine start is requested. An engine start may be requested via a human driver pressing a button, turning a key switch, or via a request input to another human / machine interface. Alternatively, an engine start request may be made via a controller in response to vehicle operating conditions. The value of a variable in memory may indicate whether an engine start is requested. If method 400 determines that an engine start request has been issued, the answer is yes and method 400 proceeds to 408. Otherwise, the answer is no and method 400 proceeds to exit.

[0058] At 408, method 400 requests activation of a vehicle system power source (e.g., a 48 VDC power system) and activates it. Additionally, when the vehicle system power source is available to provide power to the electric turbocharger, method 400 requests a power contactor (e.g., Figure 1 The vehicle system power supply may be closed by a series of diagnostics and self-tests before it can be used to provide power to the electric turbocharger. It may take from several seconds to tens of seconds before the vehicle system power supply can be used to provide power to the electric turbocharger and before the power contactor is closed. After requesting activation of the vehicle system power supply, method 400 proceeds to 410.

[0059] At 410 , method 400 starts the engine. The engine is started by spinning the engine via an electric machine (eg, a starter motor) and by supplying spark and fuel to the engine. Method 400 proceeds to 412 .

[0060] At 412, method 400 operates the electric turbocharger in a generator mode. In the generator mode, the rotor of the electric turbocharger is rotated by the exhaust gas. The rotating rotor generates a magnetic field, and the magnetic flux from the magnetic field induces a current in the electric turbocharger stator. The output from the electric turbocharger stator is supplied to an inverter, such as Figure 2 As shown. The output of the electric turbocharger can be adjusted by adjusting the speed of the rotor by adjusting the position of the wastegate. Opening the wastegate will reduce the rotor speed and the output of the electric turbocharger. Closing the wastegate can increase the rotor speed and the output of the electric turbocharger. Therefore, by adjusting the speed of the turbocharger rotor by adjusting the position of the wastegate, the charging rate of the power filter capacitor can be adjusted because the power filter capacitor can be connected via a three-phase switch array (e.g., Figure 2 The method 400 proceeds to 414.

[0061] At 414, method 400 activates the inverter and begins switching the three-phase switch array (eg, Figure 2 210-215) to start the power filter capacitor (e.g., Figure 2 The switch may be operated via pulse width modulation to convert AC current from the electric turbocharger motor into DC current. The DC current then charges the power filter capacitor. In some examples, the power filter capacitor may be charged while not charging the variable voltage converter capacitor (e.g., Figure 2 After the power filter capacitor charge reaches the threshold charge, the buck transistor 206 may be activated to supply charge to the converter capacitor. The method 400 proceeds to 416.

[0062] At 416, method 400 determines whether the power filter capacitor is charged to a threshold level, or whether the power contactor is closed or whether there is an indication that the power contactor will be closed within a predetermined amount of time. Method 400 can monitor the power filter capacitor voltage to determine whether the power filter capacitor is charged to a threshold charge amount. The vehicle system power supply can provide the status of the power contactor to the controller. If method 400 determines that the power filter capacitor is charged to a threshold level, or if the power contactor is closed or alternatively, if there is an indication that the power contactor will be closed within a predetermined amount of time, the answer is yes and method 400 proceeds to 418. Otherwise, the answer is no and method 400 returns to 408.

[0063] At 418 , method 400 operates the electric turbocharger in the motor mode. However, before the electric turbocharger operates in the motor mode, if the power capacitor is not charged to the threshold charge level, the vehicle system power supply charges the power capacitor to the threshold charge level.

[0064] In motor mode, DC power at node 201 of the inverter is switched to the three-phase armature winding of the electric turbocharger's motor 143 via three-phase array transistors 210-215 at different times to cause the motor's rotor to rotate and compress air entering the engine. Boost transistor 208 may be activated to supply power to the DC bus 285 from the vehicle system power supply. The turbocharger and three-phase inverter switches (e.g., 210-215) may be deactivated until there is a positive indication that the power contactor has been closed. Method 400 proceeds to 420.

[0065] In this way, the electric turbocharger can be operated first as a generator or alternator before the power contactor is closed to charge one or more capacitors in the inverter. The capacitors in the inverter can be charged using the vehicle system power supply after the power contactor is closed to accelerate the charging of the capacitors. However, if the capacitors are charged to a threshold level before the power contactor is closed, the electric turbocharger can be operated in motor mode immediately after the power contactor is closed, thereby avoiding charging the power filter capacitors through the vehicle system power supply. By at least partially charging the power capacitors, the current rushing to the inverter can be reduced to extend the system life and reduce the stress within the electrical system.

[0066] therefore, Figure 4 The method provides an engine operation method, the engine operation method comprising: receiving an input to a controller, the input indicating a request to start the engine; and operating an electric turbocharger in a generator mode via the controller and charging a power filter capacitor connected to a DC bus in response to the received input. The method also includes delaying the operation of the electric turbocharger in a motor mode until the power contactor is closed and the voltage of the power filter capacitor is greater than a threshold voltage. The method includes a case where the operation of the electric turbocharger in a generator mode includes switching one or more transistors of an inverter to charge the power filter capacitor. The method also includes stopping switching one or more transistors of the inverter in response to the voltage of the power filter capacitor exceeding the threshold voltage. The method includes a case where the electric turbocharger includes a three-phase motor (e.g., motor 143). The method also includes starting the engine via the controller in response to the received input. The method also includes operating the electric turbocharger in a motor mode and supplying compressed air to the internal combustion engine via the electric turbocharger. The method also includes adjusting the speed of the electric turbocharger in response to the driver's demand torque.

[0067] Figure 4 The method also provides an engine operation method, which includes: receiving an input to a controller; operating an electric turbocharger in a generator mode via the controller and charging a power filter capacitor connected to a DC bus in response to the received input; and adjusting the speed of the electric turbocharger operating in the generator mode by adjusting the position of the wastegate via the controller. The method includes a case where the speed of the electric turbocharger is adjusted to control the current from the electric turbocharger to the power filter capacitor. The method includes a case where the speed is reduced in response to the voltage of the power filter capacitor exceeding a threshold voltage. The method includes a case where the wastegate is opened to reduce the speed of the electric turbocharger in response to the voltage of the power filter capacitor. The method includes a case where the wastegate is closed to increase the speed of the electric turbocharger in response to the voltage of the power filter capacitor. The method also includes starting the engine in response to the received input, and wherein the wastegate is closed during engine starting.

[0068] It should be noted 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 a non-temporary memory and can be executed by a control system including 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, etc. In this way, the various actions, operations and / or functions shown can be performed in the order shown, in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations and / or functions shown can be repeatedly performed according to the specific strategy used. In addition, at least a portion of the described actions, operations and / or functions can graphically represent the code in the non-temporary memory of a computer-readable storage medium to be programmed into the control system. When the described actions are performed by executing instructions in a system including a combination of various engine hardware components and one or more controllers, the control action can also transform the operating state of one or more sensors or actuators in the physical world.

[0069] The specification ends here. A reading of this specification by one skilled in the art will suggest many changes and modifications without departing from the spirit and scope of this specification. For example, I3, I4, I5, V6, V8, V10 and V12 engines operating in natural gas, gasoline, diesel or alternative fuel configurations may benefit from using this specification.

[0070] According to the present invention, an engine operating method includes receiving an input to a controller indicating a request to start the engine and operating an electric turbocharger in a generator mode via the controller and charging a power filter capacitor coupled to a DC bus in response to the received input.

[0071] According to an embodiment, the present invention is also characterized in that operating the electric turbocharger in the motor mode is delayed until the power contactor is closed and the voltage of the power filter capacitor is greater than a threshold voltage.

[0072] According to an embodiment, the invention is also characterized in that operating the electric turbocharger in generator mode includes switching one or more transistors of the inverter to charge a power filter capacitor.

[0073] According to an embodiment, the invention is further characterized by stopping switching of one or more transistors of the inverter in response to the voltage of the power filter capacitor exceeding a threshold voltage.

[0074] According to an embodiment, the electric turbocharger comprises a three-phase electric machine.

[0075] According to an embodiment, the invention is also characterized by starting the engine via the controller in response to the received input.

[0076] According to an embodiment, the present invention is also characterized in that the electric turbocharger is operated in a motor mode, and compressed air is supplied to the internal combustion engine via the electric turbocharger.

[0077] According to an embodiment, the invention is also characterized by adjusting the speed of the electric turbocharger in response to driver demand torque.

[0078] According to the present invention, an engine operating method includes: receiving an input to a controller; operating an electric turbocharger in a generator mode via the controller and charging a power filter capacitor connected to a DC bus in response to the received input; and adjusting a speed at which the electric turbocharger operates in the generator mode by adjusting a position of a wastegate via the controller.

[0079] According to an embodiment, the speed of the electric turbocharger is adjusted to control the current from the electric turbocharger to the power filter capacitor.

[0080] According to an embodiment, in response to the voltage of the power filter capacitor exceeding a threshold voltage, the speed is reduced.

[0081] According to an embodiment, in response to the voltage of the power filter capacitor, the wastegate is opened to reduce the speed of the electric turbocharger.

[0082] According to an embodiment, in response to the voltage of the power filter capacitor, the wastegate is closed to increase the speed of the electric turbocharger.

[0083] According to an embodiment, the invention further features starting the engine in response to the received input, and wherein the wastegate is closed during the engine starting.

[0084] According to the present invention, a system is provided, the system having: an engine; an electric turbocharger coupled to the engine; an inverter electrically coupled to the electric turbocharger, the inverter including a power filter capacitor coupled to a DC bus; a power contactor selectively coupling a DC power source to the inverter; and a controller including executable instructions stored in a non-volatile memory for starting the engine and operating the electric turbocharger in a generator mode before the power contactor is closed to charge the power filter capacitor.

[0085] According to an embodiment, an inverter includes a three-phase transistor array.

[0086] According to an embodiment, an inverter includes a buck transistor and a boost transistor.

[0087] According to an embodiment, the invention is also characterized by having additional instructions for adjusting the position of the wastegate to control the output of the electric turbocharger when the electric turbocharger is operating in the generator mode.

[0088] According to an embodiment, the invention is also characterized by having additional instructions for adjusting the position of the wastegate to control the output of the electric turbocharger when the electric turbocharger is operating in the motor mode.

[0089] According to an embodiment, the invention is also characterized by having additional instructions for stopping operation of the electric turbocharger in generator mode in response to the voltage of the power filter capacitor.

Claims

1. An engine operating method, comprising: receiving an input to a controller, the input indicating a request to start the engine; as well as An electric turbocharger is operated in a generator mode via the controller in response to the received input and a power filter capacitor coupled to a DC bus is charged. 2 . The method of claim 1 , further comprising delaying operating the electric turbocharger in a motor mode until a power contactor is closed and a voltage of the power filter capacitor is greater than a threshold voltage. 3 . The method of claim 1 , wherein operating the electric turbocharger in a generator mode comprises switching one or more transistors of an inverter to charge the power filter capacitor. 4 . The method of claim 3 , further comprising ceasing to switch the one or more transistors of the inverter in response to the voltage of the power filter capacitor exceeding a threshold voltage.

5. The method of claim 1, wherein the electric turbocharger comprises a three-phase electric machine. 6 . The method of claim 1 , further comprising starting an engine via the controller in response to the received input. 7 . The method of claim 1 , further comprising operating the electric turbocharger in a motor mode and supplying compressed air to an internal combustion engine via the electric turbocharger. 8 . The method of claim 7 , further comprising adjusting the speed of the electric turbocharger in response to driver demand torque.

9. The method of claim 1, further comprising: The speed at which the electric turbocharger operates in the generator mode is adjusted by adjusting a position of a wastegate via the controller.

10. A system comprising: engine; an electric turbocharger coupled to the engine; an inverter electrically coupled to the electric turbocharger, the inverter including a power filter capacitor coupled to a DC bus; a power contactor that selectively couples a DC power source to the inverter; as well as A controller including executable instructions stored in non-transitory memory is configured to start the engine and operate the electric turbocharger in a generator mode to charge the power filter capacitor before the power contactor is closed.

11. The system of claim 10, wherein the inverter comprises a three-phase transistor array.

12. The system of claim 10, wherein the inverter comprises a buck transistor and a boost transistor.

13. The system of claim 10 further comprising additional instructions for adjusting a position of a wastegate to control an output of the electric turbocharger when the electric turbocharger is operating in the generator mode.

14. The system of claim 10 further comprising additional instructions for adjusting a position of a wastegate to control an output of the electric turbocharger when the electric turbocharger is operating in a motor mode.

15. The system of claim 14 further comprising additional instructions for ceasing to operate the electric turbocharger in the generator mode in response to the voltage of the power filter capacitor.

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