KR102592836B1 - Hybrid vehicle and method of driving control for the same - Google Patents

Abstract

The present invention relates to a hybrid vehicle and a driving control method therefor, and more specifically, to a hybrid vehicle and a control method thereof that can efficiently cope with a cooling failure situation in a power electronic system. A driving control method of a hybrid vehicle in which an engine clutch is disposed between an engine and a drive motor according to an embodiment of the present invention includes the steps of acquiring route information; If there is a front ramp based on the path information, predicting a temperature change in the power electronics system due to driving on the ramp; determining whether it is possible to drive on the ramp with the driving motor based on the predicted temperature change; And if it is impossible as a result of the determination, it may include driving on the slope using the driving force of the engine.

Description

Hybrid vehicle and driving control method for the same {HYBRID VEHICLE AND METHOD OF DRIVING CONTROL FOR THE SAME}

The present invention relates to a hybrid vehicle and a driving control method therefor, and more specifically, to a hybrid vehicle and a control method thereof that can efficiently cope with a cooling failure situation in a power electronic system.

A hybrid vehicle (HEV: Hybrid Electric Vehicle) generally refers to a car that uses two power sources together, and the two power sources are mainly an engine and an electric motor. These hybrid vehicles are being developed recently because they not only have superior fuel efficiency and power performance compared to vehicles equipped with only internal combustion engines, but are also advantageous in reducing exhaust gases.

These hybrid vehicles can operate in two driving modes depending on which power train is driven. One of them is the electric vehicle (EV) mode, which runs only with an electric motor, and the other is the hybrid electric vehicle (HEV) mode, which obtains power by running the electric motor and engine together. Hybrid cars switch between two modes depending on driving conditions.

Figure 1 shows an example of the power train structure of a typical hybrid vehicle.

Referring to Figure 1, a parallel type (Parallel Type) equipped with an electric motor (or drive motor, 140) and an engine clutch (EC: Engine Clutch, 130) between an internal combustion engine (ICE, 110) and a transmission (150). Alternatively, the power train of a hybrid vehicle employing a TMED (Transmission Mounted Electric Drive) hybrid system is shown.

In such vehicles, generally, when the driver steps on the accelerator after starting, the motor (140, or drive motor) is first driven using power from the battery while the engine clutch (130) is open, and the power of the motor is transferred to the transmission (150). ) and the final drive (FD: 160), the wheels move (i.e. EV mode). As the vehicle gradually accelerates and a larger driving force is required, the auxiliary motor (or starter power generation motor, 120) may operate to drive the engine 110.

Accordingly, when the rotation speeds of the engine 110 and the motor 140 become the same, the engine clutch 130 is engaged and the engine 110 and the motor 140 together or the engine 110 drives the vehicle (i.e. , transition from EV mode to HEV mode). When a preset engine-off condition such as vehicle deceleration is satisfied, the engine clutch 130 is opened and the engine 110 is stopped (i.e., transition from HEV mode to EV mode). Additionally, in hybrid vehicles, the driving force of the wheels can be converted into electrical energy during braking to charge the battery, and this is called braking energy regeneration, or regenerative braking.

The starting power generation motor 120 performs the role of a starter motor when the engine is started, and operates as a generator when recovering the rotational energy of the engine after starting or when the engine is turned off, so it is called a "hybrid starter generator (HSG: Hybrid Starter) Generator”, and in some cases, “auxiliary motor”.

The parallel hybrid vehicle as described above suffers from a problem of insufficient output when the inverter that supplies power to the drive motor 140 or the drive motor 140 itself is in a poor cooling state. Specifically, cooling defects include failure of the electric water pump (EWP) that circulates coolant in the power electronics (PE) system, exceeding the inverter temperature range, inverter temperature increase rate above a certain level, coolant leak (lack) detection, and drive motor. This may mean a situation where overtemperature, etc. has occurred.

For example, when overheating occurs in the drive motor 140, control is performed to limit motor usage according to temperature in order to cool the drive motor again. This control may be referred to as de-rating control. This will be explained with reference to FIG. 2 .

Figure 2 shows an example of how general derating control is performed.

In the graph shown in FIG. 2, the horizontal axis represents the temperature of the drive motor, and the vertical axis represents allowable torque. Referring to Figure 2, there is no limit to the output torque in the Normal Operating area (i.e., 100% allowable torque), but in the De-rating area where the temperature of the drive motor exceeds the critical temperature, the temperature rises. The higher the torque, the lower the allowable torque, which causes deterioration in fuel efficiency and drivability. For example, when a torque limit occurs, the amount of regenerative braking is limited, weakening the energy recovery rate, and driving efficiency deteriorates due to a decrease in output torque in the EV driving range, leading to worsening fuel efficiency. The most serious problem is when the vehicle accelerates from a stop or when driving at low speeds on a slope. Due to the structural characteristics of parallel hybrid vehicles, it is difficult for the motor speed to be synchronized with the minimum engine speed when driving at low speeds, so it is difficult to switch to HEV mode. Transitions become difficult, and driving performance deteriorates noticeably. In particular, in situations such as Daegwallyeong where climbing must be continuous, more motor output is required and thus more heat is generated, which can further increase the impact of cooling failure and ultimately lead to a situation where climbing is impossible. This will be explained with reference to FIG. 3 .

Figure 3 is a flow chart to explain the process of problems occurring due to derating control due to cooling defects in a typical hybrid vehicle. In Figure 3, it is assumed that there is a slope ahead in a situation where a cooling failure occurs.

Referring to FIG. 3, hill driving begins with poor cooling (S310). At this time, when the climbing speed is slow, the motor is used (i.e. EV mode), and as a result, the battery is consumed, the battery state of charge (SOC) decreases, and the temperature of the power electronics (PE) system decreases due to poor cooling. It rises due to this (S320).

Although the SOC is lowered, it is difficult to switch to HEV mode due to the low speed, so the hybrid vehicle enters the series charging mode in which the HSG (120) performs charging with the power of the engine (S330).

On the other hand, if the SOC is above a certain value (e.g., minimum energy for driving) (i.e., no in S340), the ramp will continue, but the SOC decrease and the temperature of the PE system will continue to rise. Of course, since the discharge amount will be ahead of the series charge amount, if the SOC subsequently falls below a certain value (yes in S340), or if the series charging mode is entered, it becomes impossible to climb due to a decrease in output due to derating control (S350), charging and cooling For this reason, the hybrid car becomes inoperable (S360).

Ultimately, if derating control intervenes due to poor cooling, it will be difficult to switch to HEV mode, and in severe cases, driving on slopes will not be possible and problems may arise where the vehicle must stop.

The present invention is intended to provide a hybrid vehicle and a driving control method thereof that can efficiently cope with cooling failures in the power electronic system.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below. You will be able to.

In order to solve the above technical problems, a method for controlling the driving of a hybrid vehicle in which an engine clutch is disposed between an engine and a drive motor according to an embodiment of the present invention includes the steps of acquiring route information; If there is a front ramp based on the path information, predicting a temperature change in the power electronics system due to driving on the ramp; determining whether it is possible to drive on the ramp with the driving motor based on the predicted temperature change; And if it is impossible as a result of the determination, it may include driving on the slope using the driving force of the engine.

In addition, a hybrid vehicle according to an embodiment of the present invention includes an engine; drive motor; an engine clutch disposed between the engine and the drive motor; and acquire path information, and if a front ramp exists based on the path information, predict a temperature change in the power electronics system due to driving on the ramp, and connect the ramp to the drive motor based on the predicted temperature change. It may include a hybrid controller that determines whether driving is possible and, if it is not possible as a result of the determination, controls driving on the slope using the driving force of the engine.

The hybrid vehicle according to at least one embodiment of the present invention configured as described above can efficiently cope with a cooling failure situation in the power electronic system.

In particular, when there is a climbing path on the path ahead, it is possible to determine in advance whether the climbing is possible, and when the climbing is predicted to be impossible, the climbing can be performed using engine power.

The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. will be.

Figure 1 shows an example of how general derating control is performed.
Figure 2 shows an example of the power train structure of a typical hybrid vehicle.
Figure 3 is a flow chart to explain the process of problems occurring due to derating control due to cooling defects in a typical hybrid vehicle.
Figure 4 is a block diagram showing an example of a control system of a hybrid vehicle to which embodiments of the present invention can be applied.
Figure 5 is a flowchart showing an example of a driving control method according to an embodiment of the present invention.
Figure 6 is a graph for explaining a thermal model for predicting temperature rise according to an embodiment of the present invention.

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary. Additionally, parts indicated with the same reference numbers throughout the specification refer to the same components.

Before explaining the driving control method according to the embodiment of the present invention, the control system of a hybrid vehicle to which the embodiment can be applied will first be described with reference to FIG. 4.

Figure 4 is a block diagram showing an example of a control system of a hybrid vehicle to which embodiments of the present invention can be applied. The control system shown in FIG. 4 can be applied to a vehicle to which the power train described above with reference to FIG. 2 is applied.

Referring to FIG. 4, in a hybrid vehicle to which embodiments of the present invention can be applied, the internal combustion engine 110 is controlled by the engine controller 210, and the starter power generation motor 120 and the drive motor 140 are controlled by a motor controller (MCU). : Torque can be controlled by the Motor Control Unit 220, and the engine clutch 130 can be controlled by the clutch controller 230, respectively. Here, the engine controller 210 is also called an engine control system (EMS: Engine Management System). Additionally, the transmission 150 is controlled by the transmission controller 250. In some cases, a controller for the starting power generation motor 120 and a controller for each of the driving motors 140 may be provided separately.

Each controller is connected to a hybrid controller (HCU: Hybrid Controller Unit, 240) that controls the entire mode switching process as its upper controller, and controls the driving mode change and engine clutch control when shifting gears according to the control of the hybrid controller (240). Information and/or information necessary for engine stop control may be provided to the 240 or an operation may be performed according to a control signal.

More specifically, the hybrid controller 240 determines whether to perform mode switching according to the driving state of the vehicle. For example, the hybrid controller determines the time to open the engine clutch 130 and performs hydraulic pressure (in the case of wet EC) or torque capacity control (in the case of dry EC) when the engine clutch 130 is released. Additionally, the hybrid controller 240 can determine the status of EC (lock-up, slip, open, etc.) and control the timing of stopping fuel injection of the engine 110. Additionally, the hybrid controller may control engine rotation energy recovery by transmitting a torque command for controlling the torque of the starting power generation motor 120 to the motor controller 220 for engine stop control. In addition, the hybrid controller 240 can obtain information about the slope on the front path and information about whether there is a cooling defect in order to perform a driving control method according to embodiments of the present invention, which will be described later. For example, information about the climbing route can be obtained through a navigation system or a telematics system, and whether a cooling failure has occurred can be obtained through the motor controller 220 or the engine controller 210, but are not necessarily limited thereto.

Of course, it is obvious to those skilled in the art that the above-described connection relationship between controllers and the functions/division of each controller are illustrative and are not limited to the names. For example, the hybrid controller 240 may be implemented so that the corresponding function is provided by replacing it with one of the other controllers, or the corresponding function may be distributed and provided by two or more of the other controllers.

Below, based on the above-described vehicle structure, a more efficient driving control method according to an embodiment of the present invention will be described.

In one embodiment of the present invention, forward path information is obtained, and based on this, if there is a slope ahead, it is determined whether driving on the slope road is possible, and if it is determined that driving is impossible, the slope road is driven using engine power. suggest to do

Figure 5 is a flowchart showing an example of a driving mode control method according to an embodiment of the present invention. For convenience, each process shown in FIG. 5 assumes that the hybrid controller 240 performs overall judgment and control, but is not necessarily limited thereto.

Referring to FIG. 5, first, the hybrid controller 240 obtains forward path information through the navigation system or telematics system (S501), and can check whether a ramp (i.e., a slope) within the path exists based on this (S501). S502). These processes (S501, S502) may be performed periodically or may be performed only when a cooling failure situation occurs. In addition, the forward route does not necessarily have to have a destination set in the navigation system or telematics system, and may be a route that corresponds to the driver's driving pattern (for example, on a weekday, on the way to/from work, etc.), or may be a simple route of the road currently being driven. It can also mean the front.

If a ramp exists (Yes in S502), the hybrid controller 240 can predict the temperature increase of the PE system when driving in EV mode based at least on the slope and length of the ramp (S503).

At this time, the temperature rise of the PE system may mean the temperature rise of the inverter, and prediction can be performed using a temperature rise model. The temperature rise model is explained with reference to FIG. 6. Figure 6 is a graph for explaining a thermal model for predicting temperature rise according to an embodiment of the present invention.

First, to create a temperature model, as shown in FIG. 6, data obtained by varying the required torque (Tq_req) and the temperature change according to the passage of operation time (Time_ch) for each average gradient are prepared. It may be desirable for the vehicle manufacturer to configure such data through principle testing rather than collecting it in real time by individual vehicles, but it is not necessarily limited to this.

Once the data is obtained, a temperature estimation equation that can generalize the data can be obtained for each average gradient. This estimation equation can be determined based on the temperature correlation between the operation time for each gradient (T_ch) and the current motor temperature (M_Tmp). For example, the estimation equation may have the form of Equation 1 below.

The estimation equation such as Equation 1 has the form of multiplying the operation time (T_ch) by a quadratic equation with the current motor temperature (M_Tmp) as a variable, and the operation time and the quadratic equation each have coefficients (A, B, C) and constants (D ) can be prepared in advance in table form for each average gradient and required torque. Of course, it is obvious to those skilled in the art that the above-described estimation formula or table configuration is illustrative and not necessarily limited thereto, and that various modifications are possible.

Once these estimation equations and tables for coefficients and constants are determined for each vehicle, they can be loaded into the memory (or firmware) of the hybrid controller 270. Based on these estimation equations and tables, the hybrid controller 240 can determine the operating time by dividing the length of the gradient by the speed according to the available output of the motor in the current motor temperature and the front gradient (e.g., considering output limitations due to derating). there is. If the required torque or required hydraulic pressure does not match the previously prepared table, the temperature rise can be estimated through interpolation.

Returning to FIG. 5 , the hybrid controller 240 may determine the possibility of climbing (i.e., completing) the slope using the motor 120 based on the estimated temperature rise (S504). For example, if it is determined that the output will be limited to less than the minimum output for climbing the slope due to derating control due to temperature rise while climbing, the hybrid controller 240 may determine that driving on the slope is impossible.

As a result of the determination, if it is determined that driving is possible, the hybrid controller 240 may allow driving on an incline to be performed while maintaining the EV mode (S505).

On the other hand, if it is determined that driving is impossible, the hybrid controller 240 controls the engine controller 220 to ensure starting of the engine 110 (S506), and controls the transmission controller so that the transmission 150 enters the N range. (250) can be controlled (S507). At this time, entering the N stage can be performed when entering a coasting state or a stationary state without risk factors.

When the transmission 150 is in N gear, the hybrid controller 240 controls the clutch controller 230 so that the engine clutch 130 is engaged (S508), and when the engine clutch 130 is engaged, the type of transmission 150 is changed. The considered slip start and run can be performed (S509).

For example, when the transmission 150 is a dual clutch transmission (DCT), the engine clutch 130 is maintained in a locked up state, and the clutch of the DCT is put into a slip state to prevent the engine 110 from stalling and allow the vehicle to start. You can. That is, when the DCT's clutch is in a slip state, the idle RPM of the engine 110 can be maintained even if the axle stops, and when the RPM of the engine 110 exceeds a certain speed, the DCT's clutch may be locked up. This type of driving can be called take-up (DCT Take up) driving.

On the other hand, when the transmission 150 is a general automatic transmission (AT), the transmission does not have a clutch, so unlike in the case of DCT, the engine clutch 130 is in a slip state to prevent stalling of the engine 110 and enable starting and driving. It can be done.

Thereafter, the hybrid controller 240 may release the derating control and perform general driving control when the ramp is completed and the temperature of the power electronic system (e.g., inverter) falls to the normal range (S510).

When derating control is involved, typical hybrid vehicles attempt to climb using only the drive motor at low speeds, making it difficult to switch to HEV mode and requiring charging and cooling through stopping depending on the situation. However, in this embodiment, when a decrease in driving power is expected through judgment of the gradient of the path ahead and prediction of temperature rise, it is possible to climb using the driving power of the engine. Therefore, through the above-described driving control, the problem of not being able to climb a slope when cooling failure occurs due to various causes can be solved.

The above-described present invention can be implemented as computer-readable code on a program-recorded medium. Computer-readable media includes all types of recording devices that store data that can be read by a computer system. Examples of computer-readable media include HDD (Hard Disk Drive), SSD (Solid State Disk), SDD (Silicon Disk Drive), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. There is.

Accordingly, the above detailed description should not be construed as restrictive in all respects and should be considered illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

Claims (19)

A driving control method for a hybrid vehicle comprising an engine clutch disposed between an engine and a drive motor and a power electronics system including an inverter that supplies power to the drive motor,
Obtaining route information;
If there is a front slope based on the path information, the temperature change of the inverter due to driving on the slope is calculated using a temperature estimation equation prepared in advance based on the gradient, operation time for each required torque, and temperature correlation of the drive motor. predicting the temperature rise;
determining whether it is possible to drive on the ramp with the drive motor in consideration of a decrease in output of the drive motor due to derating control based on the temperature rise due to the predicted temperature change; and
A driving control method for a hybrid vehicle, including the step of driving on the slope using the driving force of the engine when the determination is impossible. delete delete delete According to claim 1,
The step of obtaining the route information is,
A method of controlling driving of a hybrid vehicle, which is performed when cooling of the power electronic system is defective. According to clause 5,
The cooling defect is,
A driving control method for a hybrid vehicle, including at least one of overtemperature of the drive motor, overtemperature of the inverter, abnormal temperature rise rate of the inverter, insufficient coolant, and failure of a pump circulating the coolant. According to claim 1,
If possible as a result of the determination, driving on the slope using the driving force of the driving motor. According to claim 1,
The step of driving the slope with the driving force of the engine,
securing starting of the engine;
engaging the engine clutch with the transmission in N gear; and
A driving control method for a hybrid vehicle, including starting and driving steps. According to clause 8,
The starting and driving steps are,
If the transmission is a dual-clutch transmission, starting the transmission by putting the clutch of the transmission into a slip state; or
When the transmission is an automatic transmission, a driving control method of a hybrid vehicle comprising the step of putting the engine clutch in a slip state and starting the vehicle. A computer-readable recording medium recording a program for executing the driving control method of a hybrid vehicle according to any one of claims 1 or 5 to 9. In hybrid cars,
engine;
drive motor;
a power electronics system including an inverter that supplies power to the drive motor;
an engine clutch disposed between the engine and the drive motor; and
Obtain path information, and if there is a front ramp based on the path information, the temperature change of the inverter due to driving on the ramp is prepared in advance based on the gradient, the operation time for each required torque, and the temperature correlation of the drive motor. The temperature rise is predicted using a temperature estimation equation, and based on the temperature rise according to the predicted temperature change, it is determined whether it is possible to drive on the ramp with the drive motor in consideration of the decrease in output of the drive motor due to derating control. And, if the determination is not possible, a hybrid vehicle comprising a hybrid controller that controls driving on the slope using the driving force of the engine. delete delete delete According to claim 11,
The hybrid controller,
A hybrid vehicle that acquires the route information when cooling of the power electronic system is poor. According to claim 15,
The cooling defect is,
A hybrid vehicle including at least one of overtemperature of the drive motor, overtemperature of the inverter, abnormal temperature increase rate of the inverter, insufficient coolant, and failure of a pump circulating the coolant. According to claim 11,
The hybrid controller,
If, as a result of the determination, it is possible to drive on the slope with the drive motor, the hybrid vehicle is controlled to drive on the slope with the driving force of the drive motor. According to claim 11,
The hybrid controller,
A hybrid vehicle that secures starting of the engine and controls the engine clutch to be engaged with the transmission in N gear to enable starting and running. According to clause 18,
The hybrid controller,
If the transmission is a dual-clutch transmission, the clutch of the transmission is put into a slip state to control the start-up,
When the transmission is an automatic transmission, the hybrid vehicle is controlled to perform the start by putting the engine clutch in a slip state.