Hybrid electric vehicle and starting control method thereof

Abstract

The invention relates to a hybrid electric vehicle and a start control method thereof. A hybrid electric vehicle includes a powertrain including an engine, an electric machine, and a shaft to which the engine and the electric machine are connected together. The vehicle also includes a controller configured to predict a torque change of the shaft during the start by determining whether to apply a vibration contribution due to the combustion pressure torque according to whether an initial burst has occurred during the start of the engine, and control a torque of the electric machine during the start based on the predicted torque change, the controller is capable of reducing vibrations during starting of a hybrid electric vehicle and improving startability by predicting vibrations during starting and applying an anti-phase torque.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a hybrid electric vehicle capable of reducing vibration and enhancing startability during startup, and a drive control method thereof. BACKGROUND

[0002] Recently, as environmental concerns increase, the use of environmentally friendly vehicles using an electric motor as a power source is increasing. The environmentally friendly vehicle is also referred to as an electrified vehicle, and representative examples thereof can include a hybrid electric vehicle (HEV) or an electric vehicle (EV).

[0003] A powertrain of a hybrid electric vehicle can include a starter motor and an internal combustion engine connected to one shaft. The hybrid electric vehicle can increase the rotational speed of the engine to a target RPM using the starter motor connected to the engine and maintain it, and can start the engine by burning the fuel injected into the cylinder of the engine. During the engine startup process, before the target RPM is reached, the rotational speed of the engine can be increased by controlling the motor to output an applied torque greater than the engine friction torque, and after the target rotational speed is reached, the target RPM (or idle RPM) can be maintained by making the motor output the same applied torque as the engine friction torque.

[0004] However, in the actual engine startup process, in addition to the friction torque, a pumping torque also causes a mechanical loss component of the engine. The pumping torque can cause a large variable torque during the engine startup process, which not only can cause vibration of the hybrid electric vehicle during the engine startup process, but also requires the starter motor to be able to apply a greater average torque. SUMMARY

[0005] The present disclosure provides a hybrid electric vehicle and a drive control method thereof capable of reducing vibration caused by a change in mechanical loss torque of an engine during an engine startup process and enhancing startability by reducing an average required torque required until the startup is completed.

[0006] The technical subject matter pursued by the present disclosure is not limited to the above-described technical subject matter, and other technical subject matters not mentioned can be clearly understood by those skilled in the art to which the present disclosure pertains through the following description.

[0007] To achieve the above object, a method for controlling a hybrid electric vehicle according to an embodiment of the present disclosure can include changing whether to apply a combustion pressure torque-induced vibration contribution according to whether a first kick has occurred during startup of an engine; and predicting a torque variation of a shaft to which the engine and a motor are connected together during the startup; and controlling a torque of the motor during the startup based on the predicted torque variation.

[0008] According to embodiments of the present invention, predicting the torque variation during the start-up can include predicting the torque variation, before the first explosion, taking into account the vibrational contribution of the electric motoring pressure torque of the electric machine and the inertial torque of the engine; and predicting the torque variation, after the first explosion, taking into account the vibrational contribution of the electric motoring pressure torque, the inertial torque and the combustion pressure torque.

[0009] According to embodiments of the present invention, controlling the torque of the electric machine can include, before the first explosion, performing (e.g., providing) control to add a correction torque, resulting from inverting a positive (+) component of the predicted torque variation, to the electric motoring average torque, in case the electric motoring average torque resulting in the electric motoring pressure torque is less than a preconfigured maximum electric motoring torque.

[0010] According to embodiments of the present invention, controlling the torque of the electric machine can include, before the first explosion, performing (e.g., providing) control to add a correction torque, resulting from inverting a negative (-) component of the predicted torque variation, to the electric motoring average torque, in case the electric motoring average torque resulting in the electric motoring pressure torque is less than a preconfigured maximum electric motoring torque.

[0011] According to embodiments of the present invention, controlling the torque of the electric machine can include, after the first explosion, performing (e.g., providing) control to add a correction torque, resulting from inverting the total predicted torque variation, to the electric machine drive average torque.

[0012] According to embodiments of the present invention, the inertial torque, the electric motoring pressure torque, and the combustion pressure torque can be determined based on a crank angle position of the engine, a rotational speed of the shaft, and the electric motoring average torque.

[0013] According to embodiments of the present invention, the crank angle position of the engine can be determined by adding a preconfigured offset to a resolver position of the electric machine.

[0014] According to embodiments of the present invention, the preconfigured offset can be configured to have a minimum amplitude level of the vibration during the start-up when a torque resulting from summing an antiphase of the torque variation predicted according to the position of the engine with the electric motoring average torque is applied to the electric machine.

[0015] According to embodiments of the present invention, the amplitude level of the vibration during the start-up can be determined based on a square of a change in the rotational speed of the electric machine, and the inertial torque can be determined based on a preconfigured table, based on the crank angle position of the engine and the rotational speed of the shaft.

[0016] According to embodiments of the present disclosure, an electric cranking pressure torque can be determined based on a crank angle position of the engine, a rotational speed of the engine, and an electric cranking average torque, and a combustion pressure torque can be determined based on the crank angle position of the engine, the rotational speed of the engine, and the electric cranking average torque.

[0017] A hybrid electric vehicle according to embodiments of the present disclosure can include a powertrain including an engine, an electric machine, and a shaft to which the engine and the electric machine are connected together, and a controller configured to change whether or not a vibration contribution of a combustion pressure torque is applied to predict a torque change of the shaft during a startup of the engine according to whether or not a first kick has occurred during the startup, and control a torque of the electric machine during the startup based on the predicted torque change.

[0018] According to embodiments of the present disclosure, the controller can be configured to predict a torque change, before the first kick, taking into account vibration contributions of an electric cranking pressure torque of the electric machine and an inertial torque of the engine, and predict a torque change, after the first kick, taking into account vibration contributions of the electric cranking pressure torque, the inertial torque, and the combustion pressure torque.

[0019] According to embodiments of the present disclosure, the controller can be configured to, before the first kick, control the torque of the electric machine so as to add a correction torque obtained by reversing a positive (+) component of the predicted torque change to the electric cranking average torque, in a case where the electric cranking average torque resulting in generation of the electric cranking pressure torque corresponds to a preconfigured maximum electric cranking torque.

[0020] According to embodiments of the present disclosure, the controller can be configured to, before the first kick, control the torque of the electric machine so as to add a correction torque obtained by reversing a negative (-) component of the predicted torque change to the electric cranking average torque, in a case where the electric cranking average torque resulting in generation of the electric cranking pressure torque is less than the preconfigured maximum electric cranking torque.

[0021] According to embodiments of the present disclosure, the controller can be configured to, in the case after the first kick, control the torque of the electric machine so as to add a correction torque obtained by reversing all of the predicted torque changes to the electric cranking average torque.

[0022] According to embodiments of the present disclosure, the controller can be configured to determine the inertial torque, the electric cranking pressure torque, and the combustion pressure torque based on a crank angle position of the engine, a rotational speed of the shaft, and the electric cranking average torque.

[0023] According to an embodiment of the disclosure, the controller can be configured to determine the crank angle position of the engine by adding a preconfigured offset to a resolver position of the motor.

[0024] According to an embodiment of the disclosure, the preconfigured offset can be configured to have a minimum amplitude level of vibration during startup when a torque resulting from summing an inverse of a torque change predicted according to a position of the engine and an average torque of the motor is applied to the motor.

[0025] According to an embodiment of the disclosure, the controller can be configured to determine an amplitude level of vibration during startup based on a square of a torque change, and determine an inertial torque according to a preconfigured table based on a crank angle position of the engine and a rotational speed of the shaft.

[0026] According to an embodiment of the disclosure, the controller can be configured to determine a motoring pressure torque according to a preconfigured motoring pressure torque table based on a crank angle position of the engine, a rotational speed of the engine, and an average torque of the motor, and determine a combustion pressure torque according to a preconfigured combustion pressure torque table based on the crank angle position of the engine, the rotational speed of the engine, and the average torque of the motor.

[0027] Through the above-described various embodiments of the disclosure, the disclosure can reduce vibration during startup of a hybrid electric vehicle and reduce user discomfort due to vibration by predicting vibration and applying an inverse torque during startup.

[0028] In addition, through the above-described embodiments of the disclosure, it is possible to reduce a startup time of a hybrid electric vehicle and to reduce an average torque required during startup.

[0029] The advantageous effects obtainable from the disclosure can not be limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art to which the disclosure pertains from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0030] The above and other aspects, features, and advantages of the disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0031] Figure 1 An example of a configuration of a powertrain of a hybrid electric vehicle according to an embodiment of the disclosure is illustrated;

[0032] Figure 2 An example of a control system configuration of a hybrid electric vehicle according to an embodiment of the disclosure is illustrated;

[0033] Figure 3 A method of configuring a preconfigured offset for determining a crank angle position of an engine according to an embodiment of the disclosure is illustrated;

[0034] Figure 4 A process of outputting a correction torque by a hybrid controller is shown according to an embodiment of the disclosure;

[0035] Figure 5 An implementation example of a hybrid controller including a prediction unit for predicting a torque with reference to a table is shown according to an embodiment of the disclosure;

[0036] Figure 6 is a flowchart showing a start operation of an engine by a hybrid controller according to an embodiment of the disclosure;

[0037] Figure 7A and Figure 7B Effects of an embodiment of the disclosure are compared with those of a comparative example in a case where a time interval from start to full explosion is the same;

[0038] Figure 8A and Figure 8B A comparison between a comparative example and an embodiment of the disclosure is shown in a case where the comparative example and the embodiment have the same average applied torque. DETAILED DESCRIPTION

[0039] Hereinafter, the embodiments set forth herein will be described in detail with reference to the accompanying drawings, and the same or similar elements are given the same or similar reference numerals regardless of the figure number, and thus repetitive description thereof will be omitted. The terms "module" and "unit" for elements used in the following description are given or used interchangeably in consideration of the ease of writing the specification, and do not have different meanings or roles by themselves. Also, in describing the embodiments disclosed in the specification, when a detailed description of related known technology is determined to unnecessarily obscure the gist of the embodiments set forth herein, a detailed description thereof will be omitted. Also, it should be understood that the accompanying drawings are provided only for the understanding of the embodiments set forth herein, and the technical idea of the disclosure is not limited to the accompanying drawings and includes all modifications, equivalents, or substitutions falling within the spirit and scope of the disclosure.

[0040] The terms including ordinal numbers such as "first" and "second" can be used to describe various elements, but the elements are not limited to the terms. The above terms are used only for the purpose of distinguishing one element from other elements.

[0041] In the case where an element is referred to as being "connected" or "coupled" to any other element, it should be understood that the element can be directly connected or coupled to the other element, or intervening elements can be present therebetween. In contrast, in the case where an element is referred to as being "directly connected" or "directly coupled" to any other element, it should be understood that no other element is present therebetween.

[0042] The singular expression includes the plural expression, unless it is clear from the context that they are different.

[0043] As used herein, the expression "include" or "have" is intended to specify the presence of the mentioned features, numbers, steps, operations, elements, components, or combinations thereof, and should be interpreted as not excluding the possible presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof.

[0044] The unit or control unit included in the name such as a motor control unit (MCU) and a hybrid control unit (HCU) is only a term widely used to name a controller configured to control a specific function of a vehicle, and does not mean a general function unit. For example, in order to control a function for which the control unit is responsible, each control unit can include a communication device configured to communicate with a sensor or another control unit, a memory configured to store an operating system, a logic command, or input / output information, and at least one processor configured to determine, calculate, decide, etc. for responsible function control.

[0045] Before describing a method for starting control of a hybrid electric vehicle according to various embodiments of the present disclosure, the structure and control system of a hybrid electric vehicle applicable to the embodiments are first described.

[0046] Figure 1 An example of the configuration of a powertrain of a hybrid electric vehicle according to an embodiment of the present disclosure is shown.

[0047] Referring to Figure 1 which shows a powertrain of a hybrid electric vehicle employing a parallel type hybrid system having two electric machines 120 and 140 installed between an engine (internal combustion engine (ICE)) 110 and a transmission 150 and an engine clutch 130. Such a parallel type hybrid system is also called a transmission mounted electric device (TMED) hybrid system because the electric machine 140 is always connected to the input of the transmission 150.

[0048] Here, the first electric machine 120 of the two electric machines 120 and 140 is arranged between the engine 110 and one end of the engine clutch 130, and the crankshaft of the engine 110 and the first electric machine shaft of the first electric machine 120 are directly connected to each other and thus always rotate together. Therefore, the crankshaft angular position variation and the rotational speed of the engine 110 can be the same as the first electric machine shaft angular position variation and the rotational speed of the electric machine 120, respectively.

[0049] One end of a second motor shaft of the second motor 140 can be connected to the other end of the engine clutch 130, and the other end of the second motor shaft can be connected to an input terminal of the transmission 150.

[0050] The output of the second motor 140 is greater than the output of the first motor 120, and the second motor 140 can function as a drive motor. In addition, the first motor 120 can perform the function of a starter motor for rotating the crank to start the engine 110 during the start of the engine 110, can recover the rotational energy of the engine 110 by generating electricity when the engine is turned off, and can also perform electricity generation by supplying power to the engine 110 when the engine 110 is in an on state.

[0051] In a hybrid electric vehicle including a powertrain as shown in Figure 1 In a hybrid electric vehicle including a powertrain as shown in

[0052] After the engine 110 is started, when the rotational speed difference between the engine 110 and the second motor 140 falls within a predetermined range, the engine clutch 130 is finally engaged and the engine 110 and the second motor 140 rotate together (e.g., transition from EV mode to HEV mode). Thus, by a torque blending process, the output of the second motor 140 is reduced, while the output of the engine 110 is increased, thereby being able to satisfy the torque required by the driver. In the HEV mode, most of the required torque can be satisfied by the engine 110, and the difference between the engine torque and the required torque can be compensated for by at least one of the first motor 120 and the second motor 140. For example, considering the efficiency of the engine 110, when the torque output by the engine 110 is greater than the required torque, the first motor 120 or the second motor 140 generates as much power as the excess engine torque, and when the engine torque is less than the required torque, at least one of the first motor 120 and the second motor 140 outputs the deficient torque.

[0053] When a preconfigured engine condition, such as the case of vehicle deceleration, is satisfied, the engine clutch 130 is disengaged and the engine 110 is stopped (i.e., transition from HEV mode to EV mode). During deceleration, the driving force of the wheels is used to charge the battery through the second motor 140, and this is referred to as brake energy regeneration or regenerative braking.

[0054] Generally, for the transmission 150, a step-variable transmission clutch or a multi-plate clutch (e.g., a dual clutch transmission (DCT)) can be used.

[0055] Figure 2 An example of a control system configuration of a hybrid electric vehicle according to an embodiment of the disclosure is shown.

[0056] Referring to Figure 2 In a hybrid electric vehicle in which an embodiment of the disclosure is applicable, the internal combustion engine 110 can be controlled by an engine controller 210, the torques of the first and second electric machines 120 and 140 can be controlled by a motor controller (MCU) 220, and the engine clutch 130 can be controlled by a clutch controller 230. Here, the engine controller 210 can also be referred to as an engine management system (EMS). Further, the transmission 150 is controlled by a transmission controller 250.

[0057] The motor controller 220 can control a gate drive unit (not shown) through a control signal in the form of pulse width modulation (PWM) based on a motor angle, a phase voltage, a phase current, a required torque, etc., acquired from a motor resolver, a voltage sensor, a current sensor, etc., attached to each of the electric machines 120 and 140, and the gate drive unit can control an inverter (not shown) for driving each electric machine 120 and 140 accordingly.

[0058] Each controller can be connected to a hybrid controller (hybrid controller unit (HCU)) 240, which is a higher-level (e.g., overall) controller of each controller and controls the entire process of the powertrain including the mode transition process, and each controller can provide information for engine clutch control and / or information for engine stop control during a change in a drive mode or a gear shift to the HCU 240 according to the control of the HCU 240 or can perform an operation according to a control signal.

[0059] For example, the HCU 240 determines whether to perform a transition between the EV mode and the HEV mode or between the CD mode and the CS mode (in the case of a PHEV) according to a driving state of the vehicle. To this end, the HCU 240 determines a disengagement time (e.g., a time point) of the engine clutch 130 and performs hydraulic control during disengagement.

[0060] Further, the HCU 240 can determine a state (e.g., lock, slip, disengagement, etc.) of the engine clutch 130 and can control a fuel injection stop time (e.g., a time point) of the engine 110.

[0061] Further, the HCU 240 can transmit a torque command for controlling the torque of the first motor 120 to the motor controller 220 to stop the control of the engine 110, thereby controlling the engine rotational energy recovery. Further, the HCU 240 can determine the state of each drive source (e.g., the engine 110, the first motor 120, or the second motor 140) to satisfy the required torque, thus determine the required driving force shared by each drive source (e.g., the engine 110, the first motor 120, or the second motor 140), and transmit a torque command to the engine controller 210 or the motor controller 220 to control each drive source.

[0062] The connection relationship between the above-described controllers and the function / division of each controller are provided only as an example, and thus it will be apparent to those skilled in the art that the name thereof is not limited. For example, the HCU 240 can be implemented such that the function thereof is replaced by one of the other controllers other than the HCU, and the corresponding function can be allocated to two or more of the other controllers.

[0063] Figure 1 And Figure 2 The above-described configuration of the above-described configuration is provided only as an example of the configuration of the hybrid electric vehicle, and it will be apparent to those skilled in the art that the hybrid electric vehicle to which the embodiments can be applied is not limited to such a structure.

[0064] Before describing a detailed hybrid electric vehicle control method to which the present disclosure is applied, for the convenience of description, a type for controlling the torque of the hybrid electric vehicle is defined as follows.

[0065] The "motoring average torque" can refer to a predetermined torque pre-configured such that the first motor 120 can perform a rotational crank start and increase the engine RPM until the engine 110 reaches a target RPM or more. The motoring average torque can have a similar meaning as the "required start-up torque" of the engine 110 at the time of use.

[0066] During the start-up process, in a case where the motoring average torque corresponding to the applied torque of the motor is greater than the mechanical loss torque of the engine before reaching the target rotational speed, the RPM of the engine 110 is increased, and thus it is desirable that the motoring average torque of the first motor 120 is greater than the mechanical loss torque of the engine 110.

[0067] The "variable torque" is a variable torque generated due to friction and pumping variation in the engine 110 during the rotation of the engine 110, and the variable torque can include an inertial torque and a pressure torque.

[0068] The inertial torque is a torque generated at the crankshaft due to the reciprocating mass rotation of the engine 110 including the pistons, and the torque can be proportional to the square of the revolutions per minute (RPM) of the engine 110.

[0069] The pressure torque can be divided into an electric cranking average torque and a combustion pressure torque. The electric cranking average torque can refer to a torque variation of the crankshaft of the engine 110 generated only by the inlet and outlet of air without fuel combustion in a dynamometer (Dyno) of the engine 110. The combustion pressure torque can refer to a torque generated only by a pressure component generated by combustion after excluding the electric cranking pressure from the generated pressure during fuel combustion in the dynamometer of the engine 110.

[0070] In this case, the variable torque can be determined by changing the vibration contribution of the combustion pressure torque in the pressure torque according to whether the initial explosion occurs in the cylinder of the engine 110.

[0071] In addition, in the case of before the initial explosion, since the torque due to combustion within the cylinder of the engine 110 does not need to be considered, the variable torque can also be determined based on the vibration contributions of the inertial torque and the electric cranking pressure torque.

[0072] In addition, in the case of after the initial explosion, since the torque due to combustion within the cylinder of the engine 110 also needs to be considered, the variable torque can be determined considering all of the vibration contributions of the inertial torque, the electric cranking pressure torque, and the combustion pressure torque.

[0073] The "correction torque" can refer to a torque applied by the HCU 240 through the first motor 120 in addition to the electric cranking average torque, in order to reduce the vibration caused by the variable torque during startup and to reduce the required torque. For example, the HCU 240 can determine a torque obtained by inverting the phase of the variable torque as the correction torque, and perform (e.g., provide) control so that a torque corresponding to a torque obtained by adding the correction torque and the electric cranking average torque is output from the first motor 120.

[0074] Unless specifically limited, the "applied torque" can mean the sum of the torque output by the first motor 120 in the process of controlling the first motor 120 by the HCU 240. For example, in the process of starting the hybrid electric vehicle, the applied torque of the first motor 120 can correspond to the sum of the electric cranking average torque and the correction torque. Specifically, the applied torque in the process of starting the engine by rotating the crankshaft by the first motor 120 can also be referred to as a "start-up torque".

[0075] As described above in Figure 1As described in the description of the first embodiment, the shaft of the engine 110 and the shaft of the first motor 120 are directly connected to each other and always rotate together, and thus, information of the engine 110 can be identified based on information of the first motor 120.

[0076] For example, when the angular position of the shaft of the first motor 120 is identifiable during rotation, the angular position of the crankshaft of the engine 110 can also be identified as a value obtained by adding a preconfigured offset to the angular position of the shaft of the first motor 120.

[0077] In this case, during initial assembly, the crankshaft of the engine 110 and the shaft of the first motor 120 are assembled at a predetermined position, and thus, the offset can vary for each assembled hybrid electric vehicle.

[0078] Hereinafter, for convenience of description, the crankshaft angular position of the engine 110 can have the same meaning as the position of the engine 110 in use. Similarly, the crankshaft angular position of the first motor 120 can have the same meaning as the position of the first motor 120 in use.

[0079] Figure 3 A method of configuring an offset for determining the position of the engine 110 according to an embodiment of the disclosure is illustrated.

[0080] After the engine 110 is installed in the vehicle, upon entering an automatic offset detection mode (operation S301), the HCU 240 can control the first motor 120 to output an average motoring torque and maintain a preconfigured specific RPM (operation S302). Accordingly, the engine 110 directly connected to the first motor 120 generates a motoring torque variation while rotating at the same RPM.

[0081] When the first motor-engine shaft maintains the specific RPM, the HCU 240 can determine an initial configuration such that the offset corresponding to the difference between the shaft of the first motor 120 and the shaft of the engine 110 is configured to 0 (operation S303).

[0082] The HCU 240 can configure a position obtained by adding the configured offset to the position of the first motor 120 as a potential position of the engine 110, and predict a torque variation at the configured potential position (operation S304).

[0083] For example, the HCU 240 can determine a position obtained by adding the offset of 0 to the position of the shaft of the first motor 120, which is obtained from the resolver signal of the first motor 120, as a potential position of the engine 110 based on the offset configured as 0. Configuring the potential position of the engine 110 can mean predicting the crank angle position of the engine 110, and the electric motoring torque variation generated in the engine can be predicted with reference to such a crank angle position.

[0084] In addition, the first motor controller 220 can provide control to add the correction torque to the electric motoring average torque while the first motor 120 performs 2 revolutions, and apply the added torque to the first motor 120 (operation S305).

[0085] When the first motor 120 performs 2 revolutions, the crankshaft of the engine 110 directly connected thereto also performs 2 revolutions, and thus the HCU 240 can apply the electric motoring average torque and the correction torque to the engine 110 for 1 cycle of the engine 110 based on the variable torque corresponding to the potential position of the engine 110.

[0086] In this case, the correction torque can be determined based on the potential position and the RPM of the engine 110 and the required torque of the engine 110 according to the method described below with reference to Figure 4 and Figure 5

[0087] When the electric motoring average torque and the correction torque are applied to the first motor 220, the HCU 240 can digitize the amplitude level of the tachometer vibration (operation S306).

[0088] For example, the first motor controller 220 can differentiate the position of the resolver in the first motor 120 to obtain the rotational speed of the first motor 120, and the resolver speed value can be transmitted from the first motor controller 220 to the HCU 240 via CAN communication or the like. Thus, the HCU 240 can calculate the real-time torque variation according to the rotational speed based on the transmitted data.

[0089] In this case, the HCU 240 can obtain the square of the determined variable torque, and then digitize the amplitude level of the vibration by accumulating sample signals for a certain period.

[0090] For example, in the case of a 4-stroke engine, when 2 revolutions of the crankshaft of the engine 110 are regarded as 1 cycle, 1 / 4 cycle corresponding to each stroke can be configured as a certain cycle. Thus, the HCU 240 can digitize the amplitude level of the vibration by accumulating sample signals for a certain period based on the potential position of the engine 110. ​

[0091] However, the above-described method for digitizing the amplitude level of the vibration is provided only as an example, and in a method of measuring data and comparing the size of the frequency components, etc. of the Fourier transform, the amplitude level of the vibration can be more accurately digitized.

[0092] Further, the HCU 240 can compare whether the size of the currently configured offset is less than 180 degrees (operation S307).

[0093] If the size of the offset is less than 180 degrees (if "Yes" in operation S307), the HCU 240 can configure the offset to a value obtained by adding 1 degree to the previous offset, and repeat the above-described operations S304 to S307 (operation S308).

[0094] However, 1 degree is provided only as an example, and it will be apparent to those skilled in the art that, in consideration of the accuracy of the offset configuration and the speed of the offset configuration, 1 degree can be replaced by another value.

[0095] If the size of the offset is greater than 180 degrees (if "No" in operation S307), the offset that minimizes the amplitude level of the vibration among all the measured offsets can be configured as the final offset (operation S309).

[0096] Specifically, the HCU 240 can match the position of the engine 110 that generates the variable torque with the potential position of the engine 110 to which the correction torque obtained by reversing the variable torque is applied, in order to configure the offset that minimizes the amplitude level of the vibration of the tachometer as the final offset.

[0097] When the offset configuration is completed, the first motor controller 220 can discontinue the application torque of the first motor 120 (operation S310).

[0098] The above-described offset configuration control can be performed (for example, once) during the initial start-up after the hybrid electric vehicle is assembled.

[0099] For example, the process can be performed (for example, during the initial start-up) in the final inspection process after the vehicle is completed and before the vehicle is released, or can be performed during the initial start-up after the vehicle is delivered, and the above-described offset configuration can also be additionally performed when there is an inspection or replacement of the engine 110 or the first motor 120.

[0100] Figure 4 A process of outputting the correction torque by the HCU 240 according to an embodiment of the disclosure is illustrated.

[0101] The HCU 240 can use information related to the engine 110 to predict the correction torque. In this case, the information related to the engine 110 can include a crank angle position of the engine 110 (or a position of the engine 110), a rotational speed (or RPM), a required torque of the engine 110 (or an electric motoring average torque), etc.

[0102] Referring to Figure 4 , the HCU 240 can include an inertia torque prediction unit 241, an electric motoring pressure torque prediction unit 242, a combustion pressure torque prediction unit 243, and a correction torque prediction unit 244. Hereinafter, the functions of each prediction unit are described in detail.

[0103] First, the inertia torque prediction unit 241 can predict an inertia torque (or an inertia torque component) based on a crank angle position and a rotational speed of the engine 110.

[0104] Here, the inertia torque prediction unit 241 can determine the crank angle position of the engine 110 as a position obtained by adding a preconfigured offset to a position of the first motor 120 through a process described in Figure 3

[0105] Similarly, the inertia torque prediction unit 241 can determine the RPM of the engine 110 as the same as a value of the RPM obtained from the resolver of the first motor 120.

[0106] In this case, the inertia torque prediction unit 241 can predict the inertia torque by multiplying an inertia torque table output value corresponding to the crank angle position of the engine 110 and a square of the RPM of the engine 110 acquired by the HCU 240.

[0107] Here, the inertia torque table can be written through repeated experiments to correspond to the inertia torque according to the crank angle position of the engine 110. In this case, in order to minimize the storage amount in the HCU 240, the inertia torque table can be stored by dividing a variable torque according to the crank angle position by the square of the RPM.

[0108] In addition, the electric motoring pressure torque prediction unit 242 can predict a pressure torque based on the crank angle position, the rotational speed of the engine 110, and a required torque of the engine 110.

[0109] The electric motoring pressure torque can be divided into an electric motoring pressure torque component considering a throttle opening and an electric motoring pressure torque component in a throttle closed state.

[0110] The electric motoring pressure torque component considering the throttle opening can be predicted based on the crank angle position, the RPM of the engine 110, and the required torque of the engine 110. ​

[0111] For example, the electric cranking pressure torque prediction unit 242 can predict the full-open electric cranking pressure torque from the full-open electric cranking pressure torque table according to the crank angle position.

[0112] Here, the full-open electric cranking pressure torque table takes the engine speed of the engine 110 as a fixed parameter, and can be written in advance through repeated experiments at the time when the throttle of the engine 110 is fully open, to correspond the torque according to the crank angle position.

[0113] In this case, the electric cranking pressure torque prediction unit 242 can predict the electric cranking pressure torque component considering the opening degree of the throttle by multiplying the full-open electric cranking pressure torque by a preconfigured weight considering the RPM of the engine 110 and the required torque.

[0114] The electric cranking pressure torque component at the time when the throttle is closed can be predicted based on an idle electric cranking pressure torque table corresponding to the crank angle position of the engine 110.

[0115] Here, the idle electric cranking pressure torque table takes the engine speed of the engine 110 as a fixed parameter, and can be written based on data obtained by performing repeated experiments on the idle electric cranking torque according to the crank angle position.

[0116] Therefore, the electric cranking pressure torque prediction unit 242 can predict the electric cranking pressure torque component considering the opening degree of the throttle and the electric cranking pressure torque component in the closed state of the throttle based on the above-described methods, and can predict the electric cranking pressure torque by adding the two torque components.

[0117] The combustion pressure torque prediction unit 243 can predict the combustion pressure torque based on the crank angle position, the RPM of the engine 110, and the required torque of the engine 110.

[0118] The combustion pressure torque prediction unit 243 can predict the full-open combustion pressure torque from the full-open combustion torque table according to the crank angle position, and can predict the combustion pressure torque by multiplying the full-open combustion pressure torque by a preconfigured weight considering the RPM of the engine 110 and the required torque.

[0119] Here, the full-open combustion pressure torque table can be written based on the torque variation according to the crank angle position through repeated experiments in the state where the throttle of the engine 110 is fully open.

[0120] Here, the full-open combustion pressure torque table can be written as a two-dimensional full-open combustion pressure torque table, in which the torque variation according to the RPM of the engine 110 is additionally considered.

[0121] Further, the weight preconfigured in consideration of the RPM of the engine 110 and the required torque can be configured as a full-open torque table of the engine 110 according to the RPM.

[0122] Here, the full-open torque table of the engine 110 according to the RPM can be written by repeating experiments on the weight of the combustion pressure torque according to the RPM of the engine 110 and the required torque.

[0123] However, in the case of before the initial explosion, the vibration contribution caused by the combustion in the cylinder of the engine 110 does not need to be considered during the prediction of the correction torque, and thus, the process of predicting the combustion pressure torque by the combustion pressure torque prediction unit 243 before the initial explosion can be omitted.

[0124] The correction torque prediction unit 244 predicts the variable torque and calculates the correction torque based on the predicted inertial torque and pressure torque, and the required torque of the engine 110.

[0125] The correction torque prediction unit 244 can predict the variable torque by subtracting the required torque of the engine 110 from the value obtained by adding the inertial torque and the pressure torque.

[0126] Here, the variable torque can be determined by changing the vibration contribution of the combustion pressure torque among the pressure torques according to whether the initial explosion occurs in the cylinder of the engine 110.

[0127] For example, the variable torque before the initial explosion of the engine 110 can be determined as a torque obtained by subtracting the electric cranking average torque from a torque obtained by adding the inertial torque and the electric cranking pressure torque.

[0128] For example, the variable torque after the initial explosion of the engine 110 can be determined as a torque obtained by subtracting the electric cranking average torque from a torque obtained by adding the inertial torque, the electric cranking pressure torque, and the combustion pressure torque.

[0129] Further, the correction torque prediction unit 244 can predict the correction torque for canceling the variable torque of the engine 110 based on the predicted variable torque.

[0130] For example, the correction torque can be predicted to have a phase opposite to that of the predicted variable torque and a size identical to that of the predicted variable torque.

[0131] Figure 5 An example of an HCU including a prediction unit for predicting a torque with reference to a table according to an embodiment of the disclosure is illustrated.

[0132] Reference Figure 5FIG. 2 is a diagram illustrating a correspondence relationship between each prediction unit 241' to 244' (e.g., 241', 242', 243', 244') of the HCU 240' and a plurality of tables stored in the table operation unit 245'.

[0133] The correspondence relationship of the table used by each prediction unit is similar to that described in Figure 4 and redundant descriptions are omitted.

[0134] Figure 6 FIG. 3 is a flowchart illustrating a startup operation of the engine 110 by the HCU 240 according to an embodiment of the disclosure.

[0135] When there is a startup ignition ON command of the engine 110 (operation S601), the HCU 240 can control the first motor 120 to apply an electric cranking average torque (operation S602).

[0136] For example, the HCU 240 can transmit a torque command to the first motor controller 220 to make the first motor 120 output the electric cranking average torque, and the first motor controller 220 can control the first motor 120 to output the electric cranking average torque. In this case, when the first motor 120 outputs the electric cranking average torque, the engine 110 directly connected to the shaft of the first motor 120 can also rotate together.

[0137] In this case, the HCU 240 can predict the position of the engine 110 based on the position of the resolver of the first motor 120 (operation S603).

[0138] For example, the HCU 240 can identify the position of the first motor 120 based on the angle signal of the resolver of the motor, and determine the position of the engine 110 by adding a preconfigured offset amount.

[0139] In addition, the HCU 240 can determine whether the initial explosion of the engine 110 has occurred (operation S604).

[0140] For example, it can be determined whether the initial explosion has occurred according to whether there is a control of the spark plug by the engine controller 210 or the RPM of the engine 110. The detailed method of determining whether the initial explosion has occurred is the same as the prior art, and thus is omitted.

[0141] If it is determined that the initial explosion has not occurred (if "No" in operation S604), the HCU 240 can predict a variable electric cranking torque in real time based on the inertial torque and the vibration contribution of the electric cranking pressure torque before the initial explosion (operation S611).

[0142] Similarly to Figure 4 andFigure 5 Based on the description made above, the HCU 240 can predict the inertial torque and the motoring pressure torque based on the position, RPM, and the required torque of the engine 110, and can predict the variable torque by adding the inertial torque and the motoring pressure torque.

[0143] In this case, if the motoring average torque of the first motor 120 before the initial explosion does not use the preconfigured maximum motoring torque (if "No" in operation S612), the HCU 240 can control to output the correction torque obtained by inverting the negative (-) component in the predicted variable torque (operation S613A).

[0144] The HCU 240 can reduce the required torque of the engine 110 during the startup according to the negative (-) component of the variable torque of the engine 110 by appropriately outputting the positive (+) component of the correction torque at the required (e.g., specific) time (e.g., time point).

[0145] However, in this case, considering the amplitude level of the vibration and the startup time of the engine 110, the correction torque obtained by inverting all components including not only the negative (-) component but also the positive (+) component can be output as needed.

[0146] In addition, if the motoring average torque of the first motor 120 before the initial explosion does use the maximum motoring torque (if "Yes" in operation S612), the HCU 240 can control to output the correction torque obtained by inverting the positive (+) component of the predicted variable torque (operation S613B).

[0147] The HCU 240 can reduce the vibration of the engine 110 during the startup according to the positive (+) component of the variable torque of the engine 110 by appropriately outputting the negative (-) component of the correction torque at the required (e.g., specific) time (e.g., time point).

[0148] In this case, the above-described operations S611, S612, S613A, and S613B can be repeatedly performed until the initial explosion occurs.

[0149] If the initial explosion has occurred (if "Yes" in operation S604), the HCU 240 can predict the variable torque of the engine 110 in real time based on the vibration contributions of the inertial torque, the motoring pressure torque, and the combustion pressure torque (operation S621).

[0150] Similarly to Figure 4 and Figure 5Based on the description above, the HCU 240 can predict the inertial torque, the motoring cranking pressure torque, and the combustion pressure torque based on the position, the RPM of the engine 110, and the required torque of the engine 110, and can predict the variable torque by adding the inertial torque, the motoring cranking pressure torque, and the combustion pressure torque.

[0151] In this case, the HCU 240 can perform (e.g., provide) control such that the applied torque, which is obtained by adding the correction torque obtained by reversing the variable torque to the motoring cranking average torque, is output through the first motor 120 (operation S622).

[0152] The HCU 240 can determine whether the full explosion has occurred (operation S623), and if the full explosion has not occurred (if "No" in operation S623), the above-described operations S621 and S622 can be repeated until the full explosion occurs.

[0153] If the full explosion has occurred (if "Yes" in operation S623), the HCU 240 can discontinue the torque output of the first motor 120 (operation S624).

[0154] Here, the HCU 240 can determine whether the full explosion has occurred based on whether the RPM reaches the target rotational speed, and can determine whether the full explosion has occurred similarly to the initial explosion determination described in operation S604 above.

[0155] Hereinafter, the effects of the present disclosure are described in Figure 7B , Figure 8A and Figure 8B through a comparison between an experiment of a comparative example not applying the present disclosure and an experiment of an embodiment of the present disclosure.

[0156] Figure 7A and Figure 7B shows the effects of the embodiment of the present disclosure and the comparative example in a case where the time interval from the start to the full explosion is the same.

[0157] Referring to Figure 7A and Figure 7B , the torque / RPM graph according to the comparative example is shown in Figure 7A and the torque / RPM graph according to the embodiment is shown in Figure 7B In each graph, the horizontal axis represents time, and the vertical axis represents torque and rotational speed. Also, Figure 7A and Figure 7B the graphs in and can share the same horizontal axis (i.e., time axis).

[0158] In the comparative examples and implementations, as the starting device is turned on, the applied torque of the motor increases in each example until the average torque of the electric start is reached, and the applied torque of the motor is released from full burst, but the time interval from the start device being turned on to full burst is the same.

[0159] However, in the comparative example, only a constant electric starting average torque was used, but in this embodiment, the applied torque obtained by adding the correction torque to the electric starting average torque is lower than the applied torque in the comparative example.

[0160] In comparing the applied torque of the comparative example and the applied torque of the implementation, when the time interval before the full burst of the electric starting average torque in the implementation is configured to be the same as that in the comparative example, it can be identified that the electric starting average torque required during the start-up of the implementation is less than the electric starting average torque in the comparative example.

[0161] Therefore, compared to the comparative example, the embodiments of this disclosure can reduce the required torque of the engine 110 during startup, and thus, the same startup time can be ensured even with a first motor 120 having a relatively low rated torque compared to the comparative example.

[0162] In addition, the comparison is based on Figure 7A The applied torque in the comparative example is based on Figure 7B In the embodiment, the corresponding RPM of the engine 110 with applied torque can be determined. Due to the variable torque in the comparative example, the RPM of the engine 110 changes greatly. However, in the embodiment, the variable torque is offset by the corrective torque. Therefore, the advantage of the embodiment is that vibration can be reduced during startup because the RPM of the engine 110 changes little.

[0163] Therefore, compared with the comparative example, the embodiments of this disclosure can reduce vibration during the start-up process of the engine 110, thereby reducing user discomfort.

[0164] Figure 8A and Figure 8B A comparison between the comparative example and the embodiments of this disclosure is shown, where the comparative example and the embodiment have the same average applied torque.

[0165] refer to Figure 8A and Figure 8B The graphs showing the RPM per time for each of the comparative examples and implementations are shown in [the figure]. Figure 8A The graphs showing the applied torque per time for each of the comparative examples and embodiments are shown in the figure. Figure 8B As shown in the image. Here, Figure 8A and Figure 8BThe graphs in FIGS. 1 and 2 can share the same horizontal axis (i.e., time axis).

[0166] Referring to Figure 8A The graphs in FIGS. 1 and 2 can share the same horizontal axis (i.e., time axis). Figure 7A and Figure 7B As in the case of FIGS. 1 and 2, the RPM change in the embodiment is smaller than that in the comparative example.

[0167] Similarly, referring to Figure 8B The graphs in FIGS. 1 and 2 can share the same horizontal axis (i.e., time axis).

[0168] Therefore, in the case where the average applied torque in the embodiment is the same as that in the comparative example, the full burst time (e.g., time point) is reached faster in the embodiment than in the comparative example, thereby enabling improved startability.

[0169] Further, as in Figure 7A and Figure 7B During the start-up process, the RPM change is smaller, and thus, the amplitude level of vibration is reduced, and thus, the user's discomfort can be reduced.

[0170] The present disclosure as described above can be implemented as code in a computer readable medium recorded in a program. The computer readable medium includes all types of recording devices in which data readable by a computer system is stored. Examples of the computer readable medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc. Accordingly, the above detailed description should not be interpreted in a limiting sense, but should be considered in all aspects as illustrative only. The scope of the present disclosure should be determined by reasonable interpretation of the appended claims and all changes and modifications that fall within the equivalent range of the present disclosure should be construed as being within the scope of the present disclosure.

Claims

1. A method for controlling a hybrid electric vehicle, the method comprising: predicting a torque variation of a shaft to which an engine and an electric machine are connected together during a start-up of the engine by determining whether to apply a vibration contribution caused by a combustion pressure torque in accordance with whether a first kick occurs during the start-up; and controlling a torque of the electric machine during the start-up based on the predicted torque variation.

2. The method of claim 1, wherein, The predicting the torque variation during the start-up comprises: predicting the torque variation in consideration of a vibration contribution of an electric motoring pressure torque of the electric machine and an inertia torque of the engine before a first kick; and predicting the torque variation in consideration of the vibration contribution of the electric motoring pressure torque, the inertia torque, and the combustion pressure torque after the first kick.

3. The method of claim 2, wherein, The controlling the torque of the electric machine comprises, before the first kick, performing a control of adding a correction torque obtained by reversing a positive (+) component of the predicted torque variation to an electric motoring average torque that results in generating the electric motoring pressure torque in a case where the electric motoring average torque reaches a preconfigured maximum electric motoring torque.

4. The method of claim 2, wherein, The controlling the torque of the electric machine comprises, before the first kick, performing a control of adding a correction torque obtained by reversing a negative (-) component of the predicted torque variation to an electric motoring average torque that results in generating the electric motoring pressure torque in a case where the electric motoring average torque is less than the preconfigured maximum electric motoring torque.

5. The method of claim 2, wherein, The controlling the torque of the electric machine comprises, in a case after the first kick, performing a control of adding a correction torque obtained by reversing the entire predicted torque variation to an electric motoring average torque.

6. The method of claim 2, wherein, The inertia torque, the electric motoring pressure torque, and the combustion pressure torque are determined based on a crank angle position of the engine, a rotational speed of the crank, and an electric motoring average torque.

7. The method of claim 6, wherein, The crank angle position of the engine is determined by adding a preconfigured offset to a resolver position of the electric machine.

8. The method of claim 7, wherein, The preconfigured offset is configured to be applied to the electric machine in response to a torque obtained by summing the electric motoring average torque and an inverse of the predicted torque variation in accordance with a position of the engine so that a vibration during the start-up has a minimum amplitude level.

9. The method of claim 8, wherein, The amplitude level of the vibration during the start-up is determined based on a square of the predicted torque variation, and wherein the inertia torque is determined in accordance with a preconfigured table based on the crank angle position of the engine and the rotational speed of the crank.

10. The method of claim 6, wherein, The electric motoring pressure torque is determined in accordance with a preconfigured electric motoring pressure torque table based on the crank angle position of the engine, the rotational speed of the engine, and the electric motoring average torque, and wherein the combustion pressure torque is determined in accordance with a preconfigured combustion pressure torque table based on the crank angle position of the engine, the rotational speed of the engine, and the electric motoring average torque.

11. A hybrid electric vehicle comprising: a powertrain including an engine, an electric machine, and a shaft to which the engine and the electric machine are connected together; and a controller configured to: determine whether to apply a vibration contribution due to a combustion pressure torque based on whether a first burst occurs during a start-up of the engine to predict a torque variation of the shaft during the start-up; and control a torque of the electric machine based on the predicted torque variation during the start-up.

12. The hybrid electric vehicle of claim 11, wherein, the controller is configured to: predict the torque variation before the first burst, taking into account a vibration contribution of an electric cranking pressure torque of the electric machine and an inertia torque of the engine; and predict the torque variation after the first burst, taking into account a vibration contribution of the electric cranking pressure torque, the inertia torque and the combustion pressure torque.

13. The hybrid electric vehicle of claim 12, wherein, the controller is configured to, before the first burst, control the torque of the electric machine to add a correction torque obtained by inverting a positive (+) component of the predicted torque variation to an electric cranking average torque resulting in the electric cranking pressure torque, in case the electric cranking average torque reaches a preconfigured maximum electric cranking torque.

14. The hybrid electric vehicle of claim 12, wherein, the controller is configured to, before the first burst, control the torque of the electric machine to add a correction torque obtained by inverting a negative (-) component of the predicted torque variation to an electric cranking average torque resulting in the electric cranking pressure torque, in case the electric cranking average torque is less than a preconfigured maximum electric cranking torque.

15. The hybrid electric vehicle of claim 12, wherein, the controller is configured to, in case after the first burst, control the torque of the electric machine to add a correction torque obtained by inverting the whole predicted torque variation to an electric cranking average torque.

16. The hybrid electric vehicle of claim 12, wherein, the controller is configured to determine the inertia torque, the electric cranking pressure torque and the combustion pressure torque based on a crankshaft angular position of the engine, a rotational speed of the crankshaft and an electric cranking average torque.

17. The hybrid electric vehicle of claim 16, wherein, the controller is configured to determine the crankshaft angular position of the engine by adding a preconfigured offset to a resolver position of the electric machine.

18. The hybrid electric vehicle of claim 17, wherein, the preconfigured offset is configured to be applied to the electric machine in response to a torque obtained by summing the electric cranking average torque with an inverse of the torque variation predicted from a position of the engine, so that a vibration during the start-up has a minimum amplitude level.

19. The hybrid electric vehicle of claim 18, wherein, the controller is configured to: determine an amplitude level of the vibration during the start-up based on a square of the torque variation; and determine the inertia torque from a preconfigured table based on the crankshaft angular position of the engine and the rotational speed of the crankshaft.

20. The hybrid electric vehicle of claim 16, wherein, the controller is configured to: determine the electric cranking pressure torque from a preconfigured electric cranking pressure torque table based on the crankshaft angular position of the engine, the rotational speed of the engine and the electric cranking average torque; and determine the combustion pressure torque from a preconfigured combustion pressure torque table based on the crankshaft angular position of the engine, the rotational speed of the engine and the electric cranking average torque.

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