System and method for controlling limp-home reverse travel of a hybrid electric vehicle

Abstract

Systems and methods for controlling limp-home reverse driving of a hybrid electric vehicle are presented. A system for operating a hybrid electric vehicle includes a hybrid starter generator that generates a back electromotive force while rotating together with an engine when a condition is satisfied, the condition including ensuring starting of the engine in a state where a component of a high voltage system has failed, turning off a main relay, and opening a clutch of the engine according to a request for reverse driving, an electric motor that reversely rotates using the back electromotive force of the hybrid starter generator, an electronic load component that operates using the back electromotive force of the hybrid starter generator, and a controller that determines an engine rotation speed required for a load output value according to operation of the electric motor and the electronic load component, and limits operation of the electric motor or the electronic load component according to the determined engine rotation speed.

Description

Technical Field

[0001] This invention relates to a system and method for controlling limp-mode reversing driving of a hybrid electric vehicle. Background Technology

[0002] Hybrid electric vehicles (HEVs) are vehicles that use at least two different types of drive sources, and generally refer to vehicles that can be driven by an engine and an electric motor.

[0003] like Figure 1 As shown, the powertrain of a hybrid electric vehicle can be configured to include an engine 10, an electric motor 20, an engine clutch 30 disposed between the engine 10 and the electric motor 20 and configured to deliver or disconnect engine power, a transmission 40 configured to transfer power and output it to a drive shaft 60, a hybrid starter generator (HSG) 50, which is an electric motor connected to the crankshaft pulley of the engine 10 to start the engine and generate electricity, and a high-voltage battery 70 connected to the electric motor 20 and the hybrid starter generator 50 to be charged or discharged using a main relay 90 inserted therebetween.

[0004] In addition, inverters 81 and 82, which are configured to control the motor and the hybrid starter generator, are connected between the motor 20 and the main relay 90, and between the hybrid starter generator 50 and the relay 90, respectively.

[0005] The engine clutch 30 can be locked (engaged) or disconnected (disengaged) under the control of the hybrid power control unit (HCU), which is the top control unit of the hybrid electric vehicle.

[0006] Generally speaking, for the reverse driving of a hybrid electric vehicle, the gear shift position of the transmission 40 is controlled to reverse gear (R gear), and the reverse driving of the vehicle can be performed by the rotational power of the engine 10 or the electric motor 20 in reverse gear.

[0007] Recently, in order to reduce the cost and weight of vehicles, a method has been proposed to achieve reverse driving by using an electric motor 20 instead of the reverse (R) gear of the transmission 40.

[0008] In other words, because hybrid electric vehicles have an electric motor 20 that can rotate in the opposite direction, unlike conventional internal combustion engine vehicles, hybrid electric vehicles can engage a lower forward gear (first or second gear) in the transmission and then drive the electric motor 20 in the reverse direction, thereby enabling the vehicle to move backward.

[0009] However, during the reverse driving of a hybrid electric vehicle, there is only one way to use the power of the high-voltage battery 70 to power the reverse rotation of the electric motor 20. Therefore, if the main relay 90 is shut off due to an abnormality in the high-voltage system, such as the high-voltage battery, the electric motor 20 may not be able to be driven by the power of the high-voltage battery 70, making it impossible to perform reverse driving of the vehicle.

[0010] Therefore, a method is needed for reversing in limp-home mode, where the main relay is shut off due to a component failure in the high-voltage system.

[0011] Here, as a related technology, reference will be made. Figure 2 A method for controlling limp-mode reverse driving of a hybrid electric vehicle with a transmission that does not include a reverse gear (R gear) is described in the case of a limp-mode in which the main relay is shut off due to a failure of a component of the high-voltage system.

[0012] First, check whether the components of the high-voltage system (such as the high-voltage battery 70) are in a faulty state (S1).

[0013] Subsequently, when a component of the high-voltage system malfunctions, it indicates a failure to supply power to the electric motor. Therefore, the engine is started via engine drive for emergency driving, i.e., limp-mode driving (S2).

[0014] For example, if a high-voltage battery malfunctions (e.g., overheating, overvoltage, or overcurrent), when the battery control unit that identifies the high-voltage battery malfunction sends a fault signal to the HCU, the HCU, as an advanced control unit, can send a command to the engine control unit to start the engine, thereby starting the engine.

[0015] When the engine 10 is started, the main relay 90 is shut off by the HCU or battery control unit to protect the high-voltage components (S3).

[0016] At this time, if the driver requests to reverse, that is, if the driver shifts the gear lever to reverse, the engine clutch 30 will be disengaged under the control of the HCU (S4).

[0017] The engine clutch 30 disengages because the rotation direction of the engine 10 and the rotation direction of the electric motor 20 used for reversing the vehicle are opposite to each other.

[0018] Subsequently, when the hybrid starter generator 50 connected to the engine rotates with the engine 10 as the engine starts, it generates a back electromotive force, and the electric motor 20 uses the back electromotive force to rotate in the opposite direction (S5).

[0019] For example, when the motor control unit performs pulse width modulation (PWM) control on the back electromotive force generated by the hybrid starter generator 50 as the engine 10 rotates to perform constant voltage control, the constant voltage according to the constant voltage control can be stored in the DC link capacitor through the inverter 80 included in the motor control unit, and the stored constant voltage can be provided to the motor 20, so the motor 20 can rotate in the opposite direction.

[0020] Therefore, the vehicle's reversing motion is performed by the reverse rotation of the electric motor 20.

[0021] At this time, in order to prevent the motor from failing to drive due to insufficient voltage during reverse driving, the output of the motor 20 can be easily ensured by prohibiting the operation of electronic load components (such as low-voltage DC / DC converters (LDC) and air conditioning compressors) that are unnecessary for reverse driving.

[0022] In other words, the constant voltage obtained by constant voltage control of the back electromotive force of the hybrid starter generator is used only to drive the electric motor for reversing, and is limited to not being consumed by electronic load components (such as LDC and air conditioning compressor) that are unnecessary for reversing.

[0023] Therefore, the available output of the motor can be further ensured by limiting the operation of electronic load components such as LDC and air conditioning compressor.

[0024] However, when the output of the back electromotive force generated by the hybrid starter generator is equal to or higher than the output of the motor due to the increase in the speed or torque of the motor, that is, when the current output of the motor is greater than the reference value by comparing the current output of the motor with the reference value (the output is equal to or higher than the back electromotive force of the hybrid starter generator) (S6), the constant voltage control PWM control performed for the back electromotive force of the hybrid starter generator may be deactivated (S7), which makes it impossible to perform limp mode reverse driving.

[0025] In addition, during the aforementioned limp mode reversing operation, operation of electronic load components (such as LDC and air conditioning compressor) is prohibited. This may not only cause inconvenience to passengers, but may also cause the vehicle to stop due to the reduced state of charge of the 12V auxiliary battery charged by the LDC.

[0026] The information disclosed in this background section is only for enhancing the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0027] This invention relates to a system and method for controlling limp-mode reverse driving of a hybrid electric vehicle. A specific embodiment relates to a system and method for controlling limp-mode reverse driving of a hybrid electric vehicle, which allows operation of power-consuming components other than the electric motor using the back electromotive force of a hybrid starter generator when reverse driving of a hybrid electric vehicle having a transmission that does not include a reverse gear (R gear) is performed by driving an electric motor.

[0028] Therefore, embodiments of the present invention can solve problems associated with related technologies, and embodiments of the present invention provide a system and method for controlling limp-mode reverse driving of a hybrid electric vehicle, which can prevent the PWM control of constant voltage control for the back EMF of the hybrid starter generator from being released, while allowing electronic load components such as LDC and air conditioning compressor to operate when a hybrid electric vehicle with a transmission that does not include a reverse gear (R gear) performs limp-mode reverse driving by using the back EMF of the hybrid starter generator to drive the electric motor.

[0029] An exemplary embodiment of the present invention provides a system for controlling limp-mode reverse driving of a hybrid electric vehicle having a transmission that does not include a reverse gear. The system includes a hybrid starter generator configured to generate a back electromotive force (EMF) while rotating with the engine, in the event of a failure of a component of a high-voltage system, when conditions are met to ensure engine starting, disconnection of the main relay, and disengagement of the engine clutch upon request for reverse driving; an electric motor that uses the back EMF of the hybrid starter generator to rotate in the opposite direction for reverse driving; an electronic load assembly that operates using the back EMF of the hybrid starter generator; and a control unit configured to determine the engine speed required for a load output value based on the operation of the electric motor and the electronic load assembly, and to limit the operation of the electric motor or the electronic load assembly based on the determined engine speed.

[0030] The control unit may include a load output calculation unit configured to calculate a load output value based on the operation of the electric motor and electronic load components; and an engine speed control unit configured to determine the engine speed required to calculate the load output value by the load output calculation unit, and to output a signal to limit the operation of the electric motor or electronic load components when the determined engine speed is equal to or higher than a reference speed.

[0031] The load output calculation unit can be configured to calculate the load output value by summing the load output values ​​based on the operation of the motor and electronic load components, and then input the calculated load output value to the engine speed control unit via a feedforward control method.

[0032] The engine speed control unit may include an engine speed map for each load output, which is configured to determine the engine speed required to calculate the load output value by the load output calculation unit.

[0033] Another exemplary embodiment of the present invention provides a method for controlling limp-mode reverse driving of a hybrid electric vehicle having a transmission that does not include a reverse gear. The method includes generating a back electromotive force (EMF) by a hybrid starter generator rotating with the engine, when conditions are met to ensure engine starting, main relay shutdown, and engine clutch disengagement upon request for reverse driving, in the event of a failure of a component of a high-voltage system; using the back EMF of the hybrid starter generator to reverse-rotate an electric motor for reverse driving; operating an electronic load assembly using the back EMF of the hybrid starter generator; and determining the engine speed required for a load output value based on the operation of the electric motor and the electronic load assembly, and limiting the operation of the electric motor or the electronic load assembly based on the determined engine speed.

[0034] Determining the engine speed required for the load output value, and limiting the operation of the electric motor or electronic load component based on the determined engine speed, may include having the load output calculation unit calculate the load output value based on the operation of the electric motor and electronic load component, and having the engine speed control unit determine the engine speed required for the calculated load output value, and limiting the operation of the electric motor or electronic load component when the determined engine speed is equal to or higher than a reference speed.

[0035] When the load output value is calculated by the load output calculation unit, the load output value can be calculated by summing the load output values ​​based on the operation of the motor and electronic load components.

[0036] The load output value calculated by the load output calculation unit can be input to the engine speed control unit through a feedforward control method.

[0037] When determining the engine speed required for the load output value calculated by the load output calculation unit, the engine speed control unit can determine the required engine speed for the load output value based on the engine speed map of each load output pre-built through testing.

[0038] After comparing the determined engine speed with the reference speed, when the engine speed exceeds the reference speed, the engine speed control unit can output a signal to the electric motor control unit to limit the operation of the electric motor or electronic load components.

[0039] Therefore, when the operation of the motor or electronic load components is limited by the control of the motor control unit, the current output of the motor can be controlled to be equal to or lower than the reference speed, and at the same time, the constant voltage control PWM control executed for the back electromotive force of the hybrid starter generator can be continued without being deactivated.

[0040] On the other hand, when the engine speed determined by the engine speed control unit is equal to or lower than the reference speed, the operation of the electric motor and electronic load components is maintained without restricting the operation of the electric motor or electronic load components.

[0041] With the above configuration, the embodiments of the present invention provide the following effects.

[0042] First, when the engine speed connected to the hybrid starter generator is equal to or below the reference speed, the operation of the electric motor or electronic load components can be unrestricted and will continue. This allows the vehicle to reverse using the back electromotive force of the hybrid starter generator through the reverse rotation of the electric motor. Additionally, electronic load components, such as the air conditioning compressor, can be operated, eliminating inconvenience for passengers, and the 12V auxiliary battery can be charged via LDC.

[0043] Secondly, when the engine speed connected to the hybrid starter generator exceeds the reference speed, the operation of the electric motor or electronic load components may be restricted, thereby controlling the current output of the electric motor to the reference value or less. This prevents the PWM control of the constant voltage control performed against the back EMF of the hybrid starter generator from being released, and the back EMF of the hybrid starter generator can be used to continuously drive the electric motor, which enables continuous limp mode reversing.

[0044] It should be understood that the terms “automobile,” “vehicle,” or “of a vehicle,” or other similar terms as used herein, include motor vehicles in general, such as passenger cars, including sport utility vehicles (SUVs), public vehicles, trucks, various commercial vehicles, boats including various ships and vessels, aircraft, etc., and also include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle with two or more power sources, such as a gasoline-powered vehicle and an electric vehicle.

[0045] The above and other features of embodiments of the present invention are discussed below. Attached Figure Description

[0046] The above and other features of the embodiments of the invention will now be described in detail with reference to certain exemplary examples of the embodiments of the invention shown in the accompanying drawings. These exemplary examples are given by way of example only and are therefore not intended to limit the invention.

[0047] Figure 1 This is a schematic diagram showing the powertrain system of a hybrid electric vehicle;

[0048] Figure 2 This is a flowchart illustrating a prior art method for controlling limp-mode reversing driving of a hybrid electric vehicle;

[0049] Figure 3 This is a configuration diagram illustrating a system for controlling limp-mode reversing driving of a hybrid electric vehicle according to an embodiment of the present invention; and

[0050] Figure 4 This is a flowchart illustrating a method for controlling a hybrid electric vehicle in limp mode reversing according to an embodiment of the present invention.

[0051] It should be understood that the accompanying drawings are not necessarily drawn to scale, and present slightly simplified representations of various preferred features illustrating the basic principles of embodiments of the invention. Specific design features of embodiments of the invention disclosed herein, including, for example, particular dimensions, orientations, positions, and shapes, will be determined in part by the particular intended application and environment of use.

[0052] In the accompanying drawings, reference numerals refer to the same or equivalent portions of embodiments of the invention in several figures of the drawings. Detailed Implementation

[0053] Preferred exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0054] Figure 3 This is a configuration diagram illustrating a system for controlling limp-mode reversing driving of a hybrid electric vehicle according to an embodiment of the present invention, and Figure 4 This is a flowchart illustrating a method for controlling a hybrid electric vehicle in limp mode reversing according to an embodiment of the present invention.

[0055] refer to Figure 3The control unit configured to control the hybrid electric vehicle is configured to include: an engine control unit 120 configured to control the drive of the engine 10; an electric motor control unit 110 including an inverter 80 configured to control the drive of a hybrid starter generator 50 (which is an electric motor) and the drive of a motor 20 for driving; a main relay 90 mounted on a DC link stage connected to the inverter 80 and the high-voltage battery 70, capable of being turned on / off, and configured to control the discharge of the high-voltage battery 70; an LDC 140 configured to convert the power of the high-voltage battery 70 and supply the converted power to the electric motor control unit 110 or use the converted power to charge a 12V auxiliary battery (not shown); a battery control unit 130 configured to monitor the status and charging status of the high-voltage battery; and an HCU 100, which is the top control unit of the hybrid electric vehicle.

[0056] For reference, the engine control unit 120 is referred to as the engine management system (EMS), the electric motor control unit 110 is referred to as the electric motor control unit (MCU), and the battery control unit 130 is referred to as the battery management system (BMS).

[0057] DC link capacitor 84 is mounted on the DC link stage connected to inverter 80 and high-voltage battery 70.

[0058] HCU 100 receives status information of high-voltage battery 70 from battery control unit 130 to determine whether high-voltage battery 70 has failed according to predetermined diagnostic logic, and sends a command to engine control unit 120 to start engine when it is determined that high-voltage battery 70 has failed due to overheating, overvoltage or overcurrent.

[0059] For example, if the high-voltage battery malfunctions (e.g., overheating, overvoltage, or overcurrent), when the battery control unit 130, which identifies the high-voltage battery malfunction, sends a fault signal to the HCU 100, which is an advanced control unit, the HCU 100 can send a command to the engine control unit 120 to start the engine.

[0060] At this time, the main relay 90 will not be turned off until the engine starts. Therefore, the power of the high-voltage battery 70 can be supplied to the hybrid starter generator 50, which makes it possible to start the engine according to the drive of the hybrid starter generator 50.

[0061] When the engine 10 is started, the main relay 90 is turned off by the control signal of the HCU or battery control unit, and the hybrid starter generator 50 rotates with the engine as a generator in the engine starting state.

[0062] At this time, if the driver requests to reverse, that is, if the driver shifts the gear lever to reverse, the engine clutch 30 will be disengaged under the control of HCU 100.

[0063] Therefore, since the hybrid starter generator 50 connected to the engine rotates with the engine 10 as the engine starts, a back electromotive force is generated, which is defined as the product of the rotational speed and magnetic flux of the hybrid starter generator. Thus, the electric motor 20 uses the back electromotive force to rotate in the opposite direction, which enables the vehicle to reverse.

[0064] However, the constant voltage obtained through constant voltage control of the back EMF of the hybrid starter generator is only used to drive the electric motor in limp-mode reverse driving and is limited to avoid consumption by electronic load components (such as the LDC and air conditioning compressor) unnecessary for reverse driving. Therefore, when the current output of the electric motor exceeds the reference value (output equal to or higher than the back EMF of the hybrid starter generator), the PWM control of the constant voltage control performed on the back EMF of the hybrid starter generator is released, thus preventing it from performing limp-mode reverse driving, and the state of charge of the 12V auxiliary battery charged by the LDC may decrease, resulting in vehicle stalling.

[0065] For reference, LDC 140 is used to convert the power between the high-voltage battery 70 and the low-voltage electronic load assembly 150, and to step down the high voltage of the high-voltage battery 70 to provide a stepped-down voltage to the 12V auxiliary battery and other low-voltage components in the vehicle.

[0066] To address this issue, the main focus of embodiments of the present invention is to prevent the PWM control for constant voltage control of the back EMF of the hybrid starter generator from being released, while simultaneously allowing operation of electronic load components, such as the LDC and air conditioning compressor, when the hybrid electric vehicle is driven in limp mode reversing by using the back EMF of the hybrid starter generator to drive the motor.

[0067] Therefore, a system for controlling limp-mode reverse driving of a hybrid electric vehicle having a transmission without a reverse gear, according to an embodiment of the present invention, may include a hybrid starter generator 50 configured to generate a back electromotive force (EMF) while rotating with the engine, when conditions are met to ensure engine starting, main relay shutdown, and engine clutch disengagement upon request for reverse driving, in the event of a failure of components in the high-voltage system; an electric motor 20 that uses the back EMF of the hybrid starter generator 50 to rotate in the opposite direction for reverse driving; an electronic load assembly 150 that operates using the back EMF of the hybrid starter generator 50; a load output calculation unit 112 configured to calculate a load output value based on the operation of the electric motor 20 and the electronic load assembly 150; and an engine speed control unit 122 configured to determine the engine speed required for the load output value calculated by the load output calculation unit 112, and output a signal to limit the operation of the electric motor or the electronic load assembly when the determined engine speed is equal to or higher than a reference speed.

[0068] Therefore, the engine speed control unit 122 is included in the engine control unit 120, and the load output calculation unit 112 is included in the electric motor control unit 110.

[0069] In other words, the engine control unit 120 may include both the engine speed control unit 122 and the load output calculation unit 112.

[0070] Alternatively, the engine speed control unit 122 and the load output calculation unit 112 can be configured as separate integrated control units.

[0071] In other words, the engine control unit 120 may not include both the engine speed control unit 122 and the load output calculation unit 112, or either unit 112 or 122.

[0072] The engine speed control unit 122 is configured to determine the engine speed (engine RPM) required for the load output value based on the operation of the electric motor and electronic load components, i.e. the load output value calculated by the load output calculation unit 112, and to output a signal to limit the operation of the electric motor or electronic load components when the determined engine speed is equal to or higher than the reference speed.

[0073] At this time, the engine speed control unit 122 includes an engine speed map (mapping table) for each load output constructed to determine the engine speed required to determine the load output value calculated by the load output calculation unit 112, and the engine speed map for each load output is constructed through pre-testing.

[0074] The load output calculation unit 112 is configured to calculate the load output value based on the operation of the motor and electronic load components when the motor and electronic load components consume power at a constant voltage obtained by constant voltage control of the back electromotive force of the hybrid starter generator.

[0075] At this time, the load output value calculated by the load output calculation unit 112 of the motor control unit 110 is input to the engine speed control unit 122 of the engine control unit 120 through the feedforward control method.

[0076] Therefore, when the load output value calculated by the load output calculation unit 112 becomes feedforward and is input to the engine speed control unit 122, the engine speed control unit 122 determines the engine speed based on the engine speed diagram of each load output. When the determined engine speed is equal to or lower than the reference speed, the operation of the electric motor or electronic load components is prevented from being restricted. This allows the vehicle to reverse while the electric motor 20 is rotated in the reverse direction using the back electromotive force of the hybrid starter generator 50, as described above.

[0077] On the other hand, when the determined engine speed exceeds the reference speed, the engine speed control unit 122 can output a signal to the electric motor control unit 110 to limit the operation of the electric motor or electronic load components. This causes the PWM control that prevents constant voltage control from being performed against the back electromotive force of the hybrid starter generator to be released, and the limp mode reverse driving continues.

[0078] In other words, when the engine speed is equal to or lower than the reference speed, reverse driving based on the reverse rotation of the electric motor can be performed with the PWM control of the electric motor control unit for constant voltage control of the back electromotive force of the hybrid starter generator connected to the engine not released. On the other hand, the required engine speed may not unconditionally increase depending on the increase in the load output value of the electric motor and electronic load components. Therefore, when the engine speed exceeds the reference speed, a signal for limiting the operation of the electric motor or electronic load components can be output to the electric motor control unit 110, which causes the PWM control for constant voltage control that prevents the back electromotive force of the hybrid starter generator from being released, and thus, limp-mode reverse driving can continue.

[0079] Here, we will refer to Figure 3 and Figure 4 The method for controlling limp-mode reversing of a hybrid electric vehicle according to an embodiment of the present invention is described in detail step by step.

[0080] First, check whether the components of the high-voltage system (such as the high-voltage battery 70) are in a faulty state (S101).

[0081] Subsequently, when a component of the high-voltage system is in a faulty state, it indicates a condition where power may not be supplied to the electric motor. Therefore, the engine is started for emergency driving, i.e., limp-mode driving (S102), driven by the engine.

[0082] For example, if the high-voltage battery malfunctions (e.g., overheating, overvoltage, or overcurrent), when the battery control unit 130, which identifies the high-voltage battery malfunction, sends a fault signal to the HCU 100, the HCU 100, as an advanced control unit, can send a command to the engine control unit 120 to start the engine.

[0083] When the engine 10 is started, the main relay 90 is shut off by the HCU 100 or the battery control unit 130 to protect the high-voltage components (S103).

[0084] At this time, if the driver requests to reverse, that is, if the driver shifts the gear lever to reverse, the engine clutch 30 will be disengaged under the control of HCU 100 (S104).

[0085] The engine clutch 30 disengages because the rotation direction of the engine 10 and the rotation direction of the electric motor 20 used for reversing the vehicle are opposite to each other.

[0086] Subsequently, when the hybrid starter generator 50 connected to the engine rotates with the engine 10 as the engine starts, it generates a back electromotive force, and the electric motor 20 uses the back electromotive force to rotate in the opposite direction (S105).

[0087] For example, when the motor control unit performs pulse width modulation (PWM) control with constant voltage control for the back electromotive force generated by the hybrid starter generator 50 rotating together with the engine 10, the constant voltage according to the constant voltage control can be stored in the DC link capacitor 84 via the inverter 80 included in the motor control unit, and the stored constant voltage can be provided to the motor 20, so that the motor 20 can rotate in the reverse direction.

[0088] Therefore, the vehicle's reversing motion is performed by the reverse rotation of the electric motor 20.

[0089] Additionally, the motor control unit allows operation of electronic load components 150, such as LDC 140 and air conditioning compressor, and thus, a constant voltage stored in DC link capacitor 84 can be provided to LDC 140 and electronic load components 150, making it possible to operate LDC 140 and electronic load components 150 (S106).

[0090] Therefore, during the aforementioned limp-mode reversing operation, electronic load components 150, such as the LDC and air conditioning compressor, can be operated, which not only eliminates inconvenience for passengers but also allows the 12V auxiliary battery to be charged via the LDC 140.

[0091] At this time, the load output calculation unit 112 of the motor control unit 110 calculates the load output value based on the operation of the motor 20 and the electronic load component 150 (S107).

[0092] In other words, when the motor 20 and the electronic load assembly 150 consume constant voltage power obtained through constant voltage control of the back electromotive force of the hybrid starter generator, the load output calculation unit 112 calculates the load output value by summing the load output values ​​based on the operation of the motor 20 and the electronic load assembly 150.

[0093] At this time, the load output value calculated by the load output calculation unit 112 of the motor control unit 110 is input to the engine speed control unit 122 of the engine control unit 120 through the feedforward control method.

[0094] Subsequently, the engine speed control unit 122 determines the engine speed (engine RPM) required for the load output value calculated by the load output calculation unit 112 (S108).

[0095] For example, the engine speed control unit 122 can determine the engine speed required for the load output value based on an engine speed map of each load output that has been pre-built through testing.

[0096] Next, the engine speed control unit 122 compares the determined engine speed with the reference speed (S109).

[0097] As a comparison result, when the determined engine speed exceeds the reference speed, the engine speed control unit 122 outputs a signal to the motor control unit 110 (S111) to limit the operation of the electric motor or electronic load components.

[0098] Therefore, the operation of the motor or electronic load assembly can be limited by the control of the motor control unit 110, and the limitation of motor operation means preventing the current output of the motor from exceeding the reference value (output equal to or higher than the back electromotive force of the hybrid starter generator) due to the increase of motor speed or torque.

[0099] Therefore, the current output of the motor can be managed to a reference value or lower, and the PWM control for constant voltage control performed against the back EMF of the hybrid starter generator can be prevented from being released. Thus, the back EMF of the hybrid starter generator can be used to continuously drive the motor, which makes it possible to perform limp-mode driving without interruption.

[0100] On the other hand, when the comparison result in step S109 indicates that the engine speed determined by the engine speed control unit 122 is equal to or lower than the reference speed, the operation of the electric motor 20 or the electronic load assembly 150 is not restricted, and therefore the operation of the electric motor 20 and the electronic load assembly 150 can continue (S110).

[0101] Therefore, as described above, while the electric motor 20 rotates in the reverse direction using the back electromotive force of the hybrid starter generator 50, the vehicle can be reversed, and electronic load components 150, such as the air conditioning compressor, can be operated, which eliminates inconvenience to passengers, and the 12V auxiliary battery can be charged via LDC 140.

[0102] Although the present invention has been described in detail above as exemplary embodiments, the scope of the present invention is not limited to the exemplary embodiments described above, and various modifications and improvements made by those skilled in the art using the basic concepts of the present invention as defined by the appended claims are also included within the scope of the present invention.

Claims

1. A system for operating a hybrid electric vehicle, the hybrid electric vehicle having a transmission that does not include a reverse gear, the system comprising: The hybrid starter generator is configured to generate a back electromotive force while rotating with the engine, provided that conditions for starting the engine, shutting off the main relay, and disengaging the engine clutch in response to a request for reverse driving are met in the event of a failure of components in the high-voltage system. The electric motor is configured to rotate in the reverse direction using the back electromotive force of the hybrid starter generator to perform reverse driving; The electronic load assembly is configured to operate using the back electromotive force of the hybrid starter generator; as well as The controller is configured to determine the engine speed required for the load output value based on the operation of the electric motor and the electronic load assembly, and to limit the operation of the electric motor or the electronic load assembly based on the determined engine speed; The controller includes: A load output calculator is configured to calculate the load output value based on the operation of the motor and the electronic load assembly; as well as An engine speed controller is configured to determine the engine speed required for the load output value calculated by the load output calculator, and to output a signal to limit the operation of the electric motor or the electronic load assembly when the determined engine speed is greater than a reference speed.

2. The system of claim 1, wherein the load output calculator is configured to calculate a load output value by summing load output values ​​based on the operation of the motor and the electronic load component, and then input the calculated load output value to the engine speed controller via a feedforward control method.

3. The system of claim 1, wherein the engine speed controller includes an engine speed map for each load output, the engine speed map being configured to determine the engine speed required to determine the load output value calculated by the load output calculator.

4. A method for operating a hybrid electric vehicle, the hybrid electric vehicle having a transmission that does not include a reverse gear, the method comprising: In the event of a component failure in the high-voltage system, a back electromotive force is generated by a hybrid starter generator that rotates with the engine, provided that the conditions for starting the engine, shutting off the main relay, and disengaging the engine clutch in response to a request for reverse driving are met. The back electromotive force of the hybrid starter generator is used to reverse the motor for reverse driving; The electronic load components are operated using the back electromotive force of a hybrid starter generator; as well as The engine speed required for the load output value is determined based on the operation of the electric motor and the electronic load assembly, and the operation of the electric motor or the electronic load assembly is limited based on the determined engine speed. The determination of the engine speed required for the load output value and the limitation of the operation of the electric motor or the electronic load assembly based on the determined engine speed include: The load output value is calculated based on the operation of the motor and the electronic load assembly; as well as The engine speed required to calculate the load output value is determined, and the operation of the electric motor or the electronic load assembly is restricted when the determined engine speed is greater than a reference speed.

5. The method of claim 4, wherein calculating the load output value comprises: The calculation is performed by summing the load output values ​​based on the operation of the motor and the electronic load assembly.

6. The method according to claim 4 further includes inputting the load output value to the engine speed controller via a feedforward control method.

7. The method of claim 4, wherein determining the engine speed comprises: The required engine speed for the load output value is determined based on an engine speed map of each load output constructed through pre-testing.

8. The method of claim 7, further comprising: The determined engine speed is compared with the reference speed; as well as In response to the engine speed exceeding the reference speed, a signal is output to limit the operation of the electric motor or the electronic load component.

9. The method of claim 8, wherein when the operation of the motor or the electronic load component is restricted in response to the signal, the current output of the motor is controlled to be equal to or less than a reference value, and simultaneously, the PWM control of constant voltage control performed for the back electromotive force of the hybrid starter generator is not released and continues.

10. The method of claim 8, wherein in response to a determined engine speed being less than or equal to the reference speed, the operation of the electric motor and the electronic load assembly is maintained without limiting the operation of the electric motor or the electronic load assembly.

11. A method of operating a hybrid electric vehicle, the hybrid electric vehicle having a transmission that does not include a reverse gear, the method comprising: Confirm the fault in the components of the high-voltage system; Start the engine; Turn off the main relay; Disengage the engine clutch; The back electromotive force of the hybrid starter generator is used to reverse the motor to perform reverse driving; Operating electronic load components; Calculate the load output values ​​of the motor and the electronic load assembly; Determine the engine speed required to calculate the load output value; Determine whether the determined engine speed is greater than the reference speed; In response to determining that the determined engine speed is greater than the reference speed, a signal is output to limit the operation of the electric motor or the electronic load assembly; as well as In response to determining that the determined engine speed is less than or equal to the reference speed, the operation of the electric motor and the electronic load assembly continues.

12. The method of claim 11, wherein calculating the load output value comprises: The calculation is performed by summing the load output values ​​based on the operation of the motor and the electronic load assembly.

13. The method according to claim 11 further includes inputting the load output value to the engine speed controller via a feedforward control method.

14. The method of claim 11, wherein determining the engine speed comprises: The required engine speed for the load output value is determined based on an engine speed map of each load output constructed through pre-testing.

15. The method of claim 11, wherein the components of the high-voltage system include a high-voltage battery.

16. The method of claim 11, wherein operating the electronic load assembly comprises: The voltage stored in the DC link capacitor is supplied to the electronic load component.

17. The method of claim 16, wherein the electronic load component comprises a low-voltage DC / DC converter or an air conditioning compressor.

18. The method of claim 16, wherein operating the electronic load assembly includes auxiliary battery charging of the electronic load assembly.

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