Battery discharge limit control system and method

Abstract

A battery discharge limit control system is provided. The system includes a motor driven by receiving power stored in a battery and a clutch connected to a rotating shaft of the motor. In addition, the engine includes a rotating shaft connected to the rotating shaft of the motor through a clutch, and the transmission changes the rotation speed of the rotating shaft of the motor or the engine based on a gear command input to output the rotation speed to a driving wheel of a vehicle. When the gear command input is a reverse gear, the controller opens the clutch and drives the motor in reverse rotation.

Description

Technical Field

[0001] The present disclosure relates to battery discharge limit control systems and methods, and more particularly, to systems and methods for controlling the discharge limit of a battery that reversely drives an electric motor during reverse operation of a hybrid vehicle without applying a transmission having a separate reverse gear. Background Art

[0002] A hybrid vehicle is an eco-friendly vehicle that provides driving force to wheels by selectively using an engine and an electric motor according to vehicle driving conditions or vehicle conditions, the engine for generating rotational force by burning fossil fuels and the electric motor for generating rotational force using electrical energy. Generally, a hybrid vehicle includes an engine clutch for selectively connecting a rotating shaft of the engine and a rotating shaft of the electric motor, a hybrid mode couples the engine clutch to provide the rotational force of the engine to the wheels, or provides the rotational force of the engine and the rotational force of the electric motor to the wheels together, and an electric vehicle mode opens the engine clutch to provide the rotational force of the electric motor to the wheels to drive the vehicle.

[0003] Some hybrid vehicles apply a technology that omits the reverse gear in the transmission provided between the power source such as the engine or the motor and the wheels, and reverses the vehicle by reversing the motor during the reverse operation. In addition, the battery that supplies electric energy to the motor limits its output according to its state of charge (SOC). For example, such a control is performed in which the output of the battery is limited to a lower level as the state of charge of the battery decreases, and thus the battery is fully discharged, thereby avoiding the vehicle from being unable to travel and ensuring operability.

[0004] For a vehicle without a reverse gear to which the battery discharge limit control is applied, when the state of charge of the battery is low, the electric motor using the power of the battery cannot be driven by the battery discharge control, and therefore, reversing of the vehicle becomes impossible. In other words, when the electric motor cannot be driven due to the battery discharge control when the vehicle is traveling forward, the vehicle can travel by driving the engine, but since the vehicle without a reverse gear can be reversed by the reverse rotation drive of the electric motor, reversing of the vehicle itself may become impossible.

[0005] The foregoing content explained as background art is only intended to help understanding the background of the present disclosure, but is not intended to indicate that the present disclosure falls within the scope of the relevant art known to those skilled in the art. Summary of the invention

[0006] Therefore, the present disclosure provides a battery discharge limit control system and method capable of smoothly supplying electric energy required for a motor driven in reverse rotation for reverse operation of the vehicle in a hybrid vehicle adopting a transmission without a reverse gear.

[0007] According to one aspect, the present disclosure provides a battery discharge limit control system, which may include: an electric motor driven by receiving electricity stored in a battery; a clutch connected to the rotating shaft of the electric motor; an engine having a rotating shaft connected to the rotating shaft of the electric motor through the clutch; a transmission; and a controller, the transmission being configured to change the rotational speed of the rotating shaft of the electric motor or the engine based on a gear command input to output the rotational speed to the drive wheels of the vehicle, the controller being configured to open the clutch and drive the electric motor in reverse rotation when the gear command input is a reverse gear.

[0008] In an exemplary embodiment of the present disclosure, the controller is configured to adjust the output of the motor by limiting the battery output based on the state of charge of the battery, and when the gear command is a reverse gear instead of a forward gear, the output of the motor is applied by increasing the output limit value that limits the output of the battery. In addition, the controller may include a first state of charge defense map, which is applied when the gear command is a forward gear and is used to store the output limit value of the battery based on the state of charge of the battery, and a second state of charge defense map, which is applied when the gear command is a reverse gear and is used to store the output limit value of the battery based on the state of charge of the battery. Under the same state of charge, the output limit value of the battery of the second state of charge defense map may be greater than the output limit value of the battery of the first state of charge defense map.

[0009] An exemplary embodiment of the present disclosure may further include a hybrid starter generator configured to start the engine and synchronize the rotation speed of the engine with the rotation speed of the motor when switching from an electric vehicle mode in which the motor is driven to rotate the drive wheels to a hybrid mode in which the engine is driven to rotate the drive wheels. In the electric vehicle mode, the controller is configured to limit the output of the battery when the gear command is a forward gear to ensure a preliminary charge amount for driving the hybrid starter generator, and to limit the output of the battery without considering the preliminary charge amount when the gear command is a reverse gear.

[0010] According to another aspect, the present disclosure provides a battery discharge limit control using the above-mentioned battery discharge limit control system, which battery discharge limit control may include determining whether the gear command is a reverse gear; and limiting the output of the battery by further increasing the output limit value that limits the output of the battery when the gear command is a reverse gear to a value greater than the output limit value when the gear command is a forward gear.

[0011] In an exemplary embodiment of the present disclosure, the controller may include a first state of charge defense map, which is applied when the gear command is a forward gear and is used to store an output limit value of the battery based on the state of charge of the battery, and a second state of charge defense map, which is applied when the gear command is a reverse gear and is used to store an output limit value of the battery, which is greater than the output limit value of the battery of the first state of charge defense map at the same state of charge. Limiting the output of the battery may include limiting the output of the battery by applying the second state of charge defense map.

[0012] The battery discharge limit control system may further include a hybrid starter generator configured to start the engine and synchronize the rotation speed of the engine with the rotation speed of the motor when switching from an electric vehicle mode in which only the motor is driven to rotate the drive wheels to a hybrid mode in which the engine is driven to rotate the drive wheels. Limiting the output of the battery may include limiting the output of the battery to ensure a preliminary charge amount for driving the hybrid starter generator when the gear command is a forward gear in the electric vehicle mode, and limiting the output of the battery without considering the preliminary charge amount when the gear command is a reverse gear.

[0013] According to the battery discharge limit control system and method, a battery output limit can be set to ensure sufficient battery charge state for reverse operation of a hybrid vehicle (the hybrid vehicle removes the reverse gear in the transmission and drives the electric motor in reverse rotation to drive the vehicle backward), thereby enhancing the reverse operability of the vehicle and improving the marketability of the vehicle.

[0014] According to a battery discharge limit control system and method, a battery output limit can be set to ensure sufficient battery charge state for reverse operation in a hybrid vehicle, which removes the reverse gear in the transmission and drives the motor in reverse rotation to drive the vehicle backward, thereby enhancing the reverse driving performance of the vehicle and improving the marketability of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description in conjunction with the accompanying drawings, in which:

[0016] Figure 1 is a block diagram illustrating a battery discharge limit control system according to an exemplary embodiment of the present disclosure.

[0017] Figure 2 is a diagram showing an example of a state of charge defense map applied to a battery discharge limit control system and method according to an exemplary embodiment of the present disclosure;

[0018] Figure 3is a diagram showing a technique for adjusting a preliminary charge amount for driving a hybrid starter generator applied in a battery discharge limit control system according to an exemplary embodiment of the present disclosure; and

[0019] Figure 4 is a flowchart illustrating a battery discharge limit control method according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] It should be understood that the term "vehicle" or "vehicle-related" or other similar terms as used herein generally include motor vehicles, such as passenger cars (including sports utility vehicles (SUVs), buses, trucks, various commercial vehicles), watercraft (including various motorboats and ships), aircraft, etc., and 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 mentioned herein, a hybrid vehicle is a vehicle with two or more power sources, such as gasoline-powered and electric-powered vehicles.

[0021] Although the exemplary embodiments are described as using multiple units to perform the exemplary processes, it should be understood that the exemplary processes can also be performed by one or more modules. In addition, it should be understood that the term controller / control unit refers to a hardware device including a memory and a processor. The memory is configured to store the modules, and the processor is specifically configured to execute the modules to perform one or more processes described further below.

[0022] In addition, the control logic of the present disclosure may be embodied as a non-transitory computer-readable medium on a computer-readable medium containing executable program instructions executed by a processor, a controller / control unit, etc. Examples of computer-readable media include, but are not limited to, ROM, RAM, compact disk (CD)-ROM, magnetic tape, floppy disk, flash drive, smart card, and optical data storage device. The computer-readable recording medium may also be distributed in a network-connected computer system so that the computer-readable medium is stored and executed in a distributed manner (e.g., by a telematics server or a controller area network (CAN)).

[0023] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that when the term "comprises / comprising" is used in this specification, the term specifies the presence of stated features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0024] Hereinafter, a battery discharge limit control system and method according to various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0025] Figure 1 is a block diagram showing a battery discharge limit control system according to an exemplary embodiment of the present disclosure. Figure 1 A battery discharge limit control system according to an exemplary embodiment of the present disclosure may include a battery 15, an electric motor 11 driven by receiving electric power stored in the battery 15, a clutch 21 connected to a rotating shaft of the electric motor 11, an engine 10 having a rotating shaft (the rotating shaft is connected to the rotating shaft of the electric motor 11 via the clutch 21), a transmission 17 and a controller 15, wherein the transmission 17 is configured to change the rotation speed of the rotating shaft of the electric motor 11 or the engine 10 based on a gear command input to output the rotation speed to a driving wheel of the vehicle, and the controller 15 is configured to open the clutch 21 and drive the electric motor 11 in reverse rotation when the gear command input is a reverse gear.

[0026] The engine 10 is an internal combustion engine for burning fossil fuels to generate rotational force, and the motor 11 is an element for converting electrical energy into rotational kinetic energy to generate rotational force. A hybrid vehicle may include two power sources (including the engine 10 and the motor 11), and when necessary, operate in an electric vehicle (EV) mode and a hybrid vehicle (HEV) mode, in which the vehicle is driven by rotating the wheels 19 using the rotational force of the motor 11, and in which the vehicle is driven by rotating the wheels 19 using the rotational force of the engine 10 or the rotational force of the engine 10 and the motor 11 together.

[0027] The rotating shaft of the engine 10 and the rotating shaft of the motor 11 can be engaged with or separated from each other through the clutch 21. In addition, the rotating shaft of the motor 11 may include an additional clutch 22 for connecting or disconnecting with the transmission 17, which includes gears for determining the number of gears. In the art, the clutch 21 arranged between the engine 10 and the motor 11 is also called an engine clutch, and the clutch for connecting the transmission 17 is also simply called a clutch. Since various exemplary embodiments of the present disclosure relate to battery discharge limit control for reverse rotation of the motor 11 during a reverse operation (the reverse operation is performed in a state where the clutch 21 has been engaged), it should be understood that the so-called clutch mainly refers to the engine clutch 21.

[0028] The transmission 17 includes gears for changing speed in the process of transmitting the rotational force provided by the engine 10 and / or the motor 11 to the wheels, and is configured to change the rotational speed transmitted to the wheels by adjusting the gear ratio. In a typical vehicle, the transmission may include a separate gear for a reverse gear engaged during a reverse operation, but various exemplary embodiments of the present disclosure may be applied to such a vehicle, in which the vehicle is reversed by the reverse rotation of the motor 11, and the transmission 17 omits a separate gear for the reverse gear. For example, when a reverse gear command is input, the transmission 17 may engage the gear of the lowest gear among the forward gears, and reverse the vehicle by the reverse rotation of the motor 11.

[0029] An exemplary embodiment of the present disclosure may include a hybrid starter generator (HSG) 13 configured to start the engine 10 and adjust the engine speed. The hybrid starter generator 13 is an electric motor configured to generate a rotational force using the power of the battery 15, and may provide the rotational force to the engine 10 for starting the engine 10 and adjusting the engine speed when the power source is switched from the electric vehicle mode to the hybrid mode.

[0030] The controller 100 is configured to operate each of the components of the hybrid vehicle as described above, and it should be understood that the controller 100 may include various controllers (e.g., a battery management system, a hybrid control unit, a motor control unit, a mission control unit, etc.) provided in the hybrid vehicle, and the controller 100 may be implemented as one or more processors and one or more memories. The controller 100 may include a state of charge defense map that limits the output of the battery 15. The output limit of the battery 15 may be generated based on the state of charge (SOC) of the battery, the battery temperature, a margin considering operability, etc., and specifically, in order to stably maintain the state of charge of the battery to ensure the operability of the hybrid vehicle, the controller 100 may include a state of charge defense map.

[0031] Figure 2is a diagram showing an example of a state of charge defense map applied to a battery discharge limit control system and method according to an exemplary embodiment of the present disclosure. Figure 2 A charge state defense map is shown. The charge state defense map may be stored in the controller 100 as a map in which the maximum output of the battery 15 is predetermined according to the charge state of the battery 15. When the hybrid vehicle is traveling forward, that is, when the gear position command for determining the gear position of the transmission 17 is a command corresponding to traveling forward, the controller 100 is configured to execute the battery discharge limit by applying the charge state defense map as indicated by reference numeral 'L1'. Figure 2 In the example of FIG. 1 , the controller 100 is configured to adjust the output of the battery 15 to zero when the state of charge of the battery 15 becomes A%.

[0032] In an exemplary embodiment of the present disclosure, the controller 100 is configured to store a state of charge defense map for reverse travel as indicated by reference numeral 'L2' in addition to the state of charge defense map for forward travel, and to apply the map during reverse travel of the vehicle (i.e., when the gear command corresponds to reverse travel). At the same state of charge, the state of charge defense map for reverse travel may be set to be greater than the state of charge defense map for forward travel in terms of the maximum output limit of the battery. Therefore, the state of charge defense map for reverse travel limits the battery output to zero at a lower state of charge B% than the state of charge defense map for forward travel.

[0033] As described above, in an exemplary embodiment of the present disclosure, the controller 100 is configured to separately apply a state of charge defense map for reverse driving, in which the output limit value of the battery 15 is set to be larger at the same state of charge to increase the application range of the battery 15 during reverse driving of the vehicle, thereby solving the following problem: since the motor 11 cannot be driven in reverse rotation due to the battery output limit in the case where the transmission 17 does not have a separate reverse gear, reverse driving of the vehicle becomes impossible. For example, when a state of charge defense map such as Figure 2 When the state of charge of the battery 15 becomes A% when the vehicle is driven, the reverse of the vehicle becomes impossible. However, when a separate defense map (such as 'L2') that applies a larger output limit value at the same state of charge is applied, the output of the battery 15 can be utilized even when the state of charge of the battery 15 becomes A%, and therefore, the reverse of the vehicle becomes possible.

[0034] At the same time, the controller 100 is configured to ensure a preliminary charge amount for driving the hybrid starter generator during forward driving of the vehicle in the electric vehicle mode to drive the hybrid starter generator 13, which operates to start the engine 10, and adjust the speed of the engine 10 for future hybrid mode driving. Figure 3 is a diagram illustrating a technique for adjusting a preliminary charge amount for driving a hybrid starter generator applied in a battery discharge limit control system according to an exemplary embodiment of the present disclosure.

[0035] The controller 100 is configured to ensure a preliminary charge amount corresponding to a margin for engine speed control in addition to the battery discharge limit as described above, which is used for future mode switching in the electric vehicle mode. The hybrid starter generator 13 is configured to start the engine 10 and adjust the rotation speed of the engine 10 to synchronize with the rotation speed of the motor in the electric vehicle mode when the driving mode of the vehicle is changed from the electric vehicle mode to the hybrid mode. Therefore, an uneven feeling such as a rattling of the vehicle due to a sudden change in speed when the clutch 21 has been engaged can be prevented.

[0036] like Figure 3 As shown, the controller 100 is configured to change the state of charge of the battery 15 to preliminarily store power for driving the hybrid starter generator 13 in the electric vehicle mode. The exemplary embodiment of the present disclosure is configured to adjust the output of the battery 15 when the vehicle is traveling forward (i.e., the gear command is a forward gear) and the vehicle is operating in the electric vehicle mode to allow the preliminary energy of the hybrid starter generator 13 for engine speed control to be stored in the battery 15. Therefore, when the vehicle is traveling forward in the electric vehicle mode, as shown in FIG. Figure 3 As shown, the preliminary charge amount set as a margin for engine speed control may be added to the lowest state of charge (A) set for the discharge limit by the state of charge defense map to enforce the discharge limit of the battery.

[0037] In addition, during the reverse travel of the vehicle, that is, when the gear command is the forward gear, it is not necessary to start the engine 10, so the preliminary charge amount setting for engine speed adjustment is removed and the output of the battery 15 is limited. Therefore, the motor 11 can be driven to reverse the vehicle until the lowest charge state set in the above-mentioned charge state defense map for reverse travel (that is, the battery output limit value is zero). As described above, the preliminary energy for engine speed adjustment can be omitted to ensure sufficient energy for the reverse of the vehicle, thereby helping to ensure reverse operability.

[0038] The present disclosure also provides a battery discharge limit control method using the above-mentioned battery discharge limit control system. Figure 4 is a flow chart showing a battery discharge limit control method according to an exemplary embodiment of the present disclosure. The method described below in this document may be executed by a controller. Figure 4 , the battery discharge limit control method according to an exemplary embodiment of the present disclosure may start from S11 (ie, the controller 100 determines whether a reverse gear is input).

[0039] In S11, in response to determining that the reverse gear has not been input, the controller 100 is configured to apply a state of charge defense map for forward travel, such as Figure 2 'L1' in. Then, the controller 100 is configured to determine the driving mode of the vehicle S16, and set the output limit of the battery 15 when the vehicle is driven in the electric vehicle mode instead of the hybrid mode to ensure the preliminary charge amount corresponding to the margin for driving the hybrid starter generator 13 S17. When the vehicle is driven in the hybrid mode in S16, the controller 100 is configured to perform the discharge limit control of the battery S14 by applying the charge state defense map applied in S15, and drive the clutch or the motor of the vehicle when necessary S18.

[0040] Meanwhile, in response to determining in S11 that the gear command is the reverse gear, the controller 100 is configured to apply a charge state defense map for reverse driving, such as Figure 2 'L2' in. Then, when the battery discharge limit is set to ensure the preliminary charge amount for driving the hybrid starter generator 13 set when driving forward in the previous electric vehicle mode, the discharge limit for ensuring the preliminary charge amount can be removed S13. Then, the controller 100 is configured to perform the battery discharge limit control by applying the charge state defense map set in S12, and drive the clutch 21 and the motor 11 to perform the reverse operation.

[0041] As described above, according to various exemplary embodiments of the present disclosure, the battery discharge limit control system and method are

[0042] A battery output limit may be set to ensure sufficient battery charge state for reverse operation in a hybrid vehicle that removes the reverse gear in the transmission and drives the motor in reverse rotation to drive the vehicle backward, thereby enhancing the reverse drivability of the vehicle and improving the marketability of the vehicle.

[0043] As described above, while the present disclosure has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various modifications and changes may be made to the present disclosure within the scope of the claims.

Claims

1. A battery discharge limit control system, the battery discharge limit control system comprising: an electric motor driven by receiving electric power stored in a battery; a clutch connected to a rotating shaft of the electric motor; an engine having a rotating shaft connected to the rotating shaft of the electric motor through the clutch; a transmission configured to: change a rotation speed of the rotating shaft of the motor or the engine based on a gear command input to output the rotation speed to a drive wheel of a vehicle; and a controller configured to: open the clutch and drive the motor in reverse rotation when the gear command input is a reverse gear; The controller is configured to adjust the output of the motor by limiting the battery output based on the state of charge of the battery, and to apply the output by increasing an output limit value that limits the output of the battery when the gear command is the reverse gear instead of the forward gear.

2. The battery discharge limit control system according to claim 1, wherein the controller comprises: a first state of charge defense map applied when the gear command is the forward gear, and the first state of charge defense map is used to store the output limit value of the battery based on the state of charge of the battery; and a second state of charge defense map applied when the gear command is the reverse gear, and the second state of charge defense map is used to store the output limit value of the battery based on the state of charge of the battery, and Wherein, under the same charging state, the output limit value of the battery in the second charging state defense diagram is greater than the output limit value of the battery in the first charging state defense diagram.

3. The battery discharge limit control system according to claim 1, further comprising: A hybrid starter generator is configured to start the engine and synchronize the rotation speed of the engine with the rotation speed of the motor when switching from an electric vehicle mode in which the electric motor is driven to rotate the drive wheels to a hybrid mode in which the engine is driven to rotate the drive wheels.

4. A battery discharge limit control system according to claim 3, wherein in the electric vehicle mode, the controller is configured to: limit the output of the battery to ensure a preliminary charge amount for driving the hybrid starter generator when the gear command is the forward gear, and limit the output of the battery without considering the preliminary charge amount when the gear command is the reverse gear.

5. A battery discharge limit control method, the battery discharge limit control method using the battery discharge limit control system according to claim 1, the battery discharge limit control method comprising the following steps: The controller determines whether the gear command is the reverse gear; and The output of the battery is limited by the controller by further increasing the output limit value that limits the output of the battery when the shift command is the reverse shift position to be greater than the output limit value when the shift command is the forward shift position.

6. The battery discharge limit control method according to claim 5, wherein the controller comprises: a first state of charge defense map applied when the gear command is the forward gear, and the first state of charge defense map is used to store the output limit value of the battery based on the state of charge of the battery; and a second state of charge defense map applied when the gear command is the reverse gear, and the second state of charge defense map is used to store the output limit value of the battery that is greater than the output limit value of the battery in the first state of charge defense map at the same state of charge, and The limiting the output of the battery includes limiting the output of the battery by the controller by applying the second state of charge defense map.

7. The battery discharge limit control method according to claim 5, wherein the battery discharge limit control system further comprises: a hybrid starter generator configured to start the engine and synchronize the rotation speed of the engine with the rotation speed of the motor when switching from an electric vehicle mode in which the motor is driven to rotate the drive wheels to a hybrid mode in which the engine is driven to rotate the drive wheels, and Wherein limiting the output of the battery comprises: In the electric vehicle mode, when the gear command is the forward gear, the controller limits the output of the battery to ensure a preliminary charge amount for driving the hybrid starter generator; and The output of the battery is limited by the controller without considering the preliminary charge amount when the gear command is the reverse gear.

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