KR20210074438A - Reverse series control method of hybrid vehicle for improving furel efficiency - Google Patents

Abstract

The present invention relates to a reverse series control method for improving fuel efficiency of a hybrid vehicle. The present invention determines whether to stop regenerative braking for protecting a high-voltage battery and forcibly rotates an engine by a hybrid starter and generator (HGS) while fuel supply to the engine is stopped, thereby performing reverse-series control consuming a charging amount of the high-voltage battery. According to the present invention, even though the battery is fully charged, the present invention continues an EV mode without stopping the regenerative braking, thereby preventing unnecessary fuel from being consumed during acceleration of a vehicle.

Description

REVERSE SERIES CONTROL METHOD OF HYBRID VEHICLE FOR IMPROVING FUREL EFFICIENCY

The present invention relates to a reverse-series control method for improving fuel efficiency of a hybrid vehicle, and more particularly, to the protection of a high voltage battery, when regenerative braking is stopped, from the EV mode to the engine like the HEV mode The present invention relates to a control method capable of suppressing a reduction in fuel efficiency due to forcible switching to the intervening driving mode.

Recently, research and development of hybrid vehicles has been actively conducted in order to improve fuel efficiency and protect the environment. And, as an example of a hybrid vehicle, as in Patent Document 1, a TMED (Transmission Mounted Electric Device) hybrid system in which an engine and a motor are connected through an engine clutch and a transmission is connected to the motor output side is known.

The TMED hybrid system charges the driving motor through the engine and the driving motor, which are the driving sources for vehicle driving, the engine clutch interposed between the engine and the driving motor, the transmission connected to the output side of the driving motor, the inverter to drive the driving motor, and the inverter. , including a battery connected to be dischargeable.

In addition, the TMED hybrid system may include a starter generator, that is, a hybrid starter and generator (HSG), which is a motor that is connected to the engine so as to transmit power to start the engine or generate power with rotational force transmitted from the engine. HSG operates as a motor or a generator, and is also used to control the engine speed because it is connected to the engine so that power can be transmitted at all times.

A vehicle equipped with such a hybrid system, that is, a hybrid vehicle such as HEV or PHEV, uses only the power of the driving motor to drive in the EV (Electric Vehicle) mode, which is a pure electric vehicle mode, or combines the power of the engine with the power of the driving motor. It can be driven in HEV (Hybrid Electric Vehicle) mode.

In addition, during braking of the vehicle or coasting due to inertia, a regenerative mode in which the kinetic energy of the vehicle is recovered through the driving motor to charge the battery is performed, and in the regenerative mode, the kinetic energy of the vehicle is transferred through the vehicle wheel The received drive motor operates as a generator to charge the connected battery through the inverter.

Patent Document 1: Republic of Korea Patent Publication No. 10-1655577 (2016.09.01)

In the case of the hybrid vehicle, as disclosed in Patent Document 1, when the battery state of charge (SOC) is greater than the threshold value, the driving mode is switched from the EV mode to the HEV mode.

When the amount of charge of the high voltage battery (SOC) exceeds a certain amount due to regenerative braking, regenerative braking and charging of the battery are stopped to protect the battery. At this time, the EV is released to maintain the deceleration level in the regenerative braking situation and the engine to maintain the deceleration using the engine brake.

However, in this process, unnecessary fuel consumption occurs, which causes a problem in that fuel efficiency is deteriorated.

The present invention has been devised to solve the above problems, and even when the charge amount of a high voltage battery exceeds a threshold value due to regenerative braking, control of a hybrid vehicle capable of improving fuel efficiency by preventing unnecessary release of the EV mode The purpose is to provide a method.

According to an aspect of the present invention, there is provided a reverse series control method for improving fuel efficiency of a hybrid vehicle, comprising: determining whether regenerative braking needs to be stopped to protect a high voltage battery; and when it is determined that it is necessary to stop regenerative braking, performing reverse-series control in which the charge amount of the high-voltage battery is consumed by forcibly rotating the engine by the HSG in a state where the fuel supply to the engine is stopped. characterized.

According to the present invention, unlike the prior art, even when it is necessary to stop the regenerative braking to protect the high voltage battery, the engine is rotated in the starter mode with the HSG without terminating the EV mode to increase the charge amount of the high voltage battery. forced to consume Therefore, according to the present invention, there is no need to stop the regenerative braking to protect the battery, and there is no need to forcibly change the driving mode to the HEV mode according to the regenerative braking is stopped. Accordingly, it is possible to prevent fuel consumption due to the switching of the driving mode.

Preferably, in the present invention, when the charge amount of the high voltage battery is equal to or greater than the first reference value, it is determined that the regenerative braking needs to be stopped to protect the high voltage battery. Therefore, according to the present invention, it is possible to determine whether the inverse series control is implemented by a simple method.

Preferably, in the present invention, in the step of determining whether it is necessary to stop the regenerative braking, when the charge amount of the high voltage battery is less than the first reference value, it is determined whether the charge amount of the high voltage battery is greater than or equal to the second reference value to do; estimating an expected amount of regenerative braking from the driving information detected by the driving information detection unit when the charge amount of the high voltage battery is equal to or greater than the second reference value; and when the calculated expected regenerative braking amount is equal to or greater than a predetermined value, it is determined that regenerative braking needs to be stopped to protect the high voltage battery.

According to the present invention, even when it is not necessary to perform the immediate reverse series control, the reverse series control is preemptively performed when there is a risk that the charging amount required for the reverse series control may be reached in a short time according to the expected amount of regenerative braking. By doing so, it is possible to more reliably bring about a fuel efficiency improvement effect.

In this case, the expected regenerative braking amount may be predicted from the current battery charge amount of the high voltage battery and the change amount of the battery charge amount for a predetermined time up to the current time point.

Also, the expected amount of regenerative braking may be predicted from at least one of a current vehicle speed, an acceleration, and an accelerator pedal effort.

Alternatively, the expected amount of regenerative braking may be predicted from at least one of current atmospheric pressure, location and altitude information input from a vehicle navigation system, and slope gradient information of a road on which the vehicle is currently traveling.

Preferably, according to the present invention, the charge amount of the high voltage battery consumed by the reverse series control is calculated, and when the charge amount of the high voltage battery consumed by the reverse series control is less than a predetermined value, an additional electrical load is forcibly operated. .

According to the present invention as described above, even when the battery cannot be sufficiently consumed by the reverse series control alone, by forcibly operating an electric load to consume the battery charge, the battery can be more reliably protected and a more reliable fuel efficiency improvement effect can be obtained. .

In this case, the electric load may be at least one of an electric load by a heat transfer device installed in the vehicle, an electric load by an air conditioning device installed in the vehicle, and an electric load by a device installed in the vehicle to relieve a thermal load.

According to the reverse series control method according to the present invention, it is possible to prevent the EV mode from being unnecessarily released by avoiding the state in which the high voltage battery is fully charged by consuming the electric energy charged in the high voltage battery at an early stage. And, through this, fuel efficiency can be improved.

In addition, according to the reverse series control method according to the present invention, it is possible to achieve an additional fuel efficiency increase effect by performing the natural regeneration of the GPF and the engine management mode (EMM) at an early stage through the engine rotation by the HSG.

1 is a view showing a hybrid system of a hybrid vehicle to which a reverse series control method according to the present invention is applied;
Fig. 2 is a flow chart showing a preferred embodiment of the inverse series control method according to the present invention;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the embodiments of the present invention. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Throughout the specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated.

In the following description, first, a configuration of a hybrid system of a hybrid vehicle to which the reverse series control method according to the present invention is applied will be described with reference to FIG. 1 .

In the hybrid vehicle, as shown in FIG. 1 , an engine 10 and a driving motor 11 , which are internal combustion engines that generate power by burning fuel, and an engine clutch 12 interposed between the engine 10 and the driving motor 11 . ), the transmission 16 connected to the output side of the drive motor 10 , and the HSG, which is a motor that is connected to the engine 10 so as to transmit power to start the engine 10 or generate power with the rotational force transmitted from the engine 10 . (Hybrid Starter and Generator) 13, inverters 14, 15 for driving HSG 13 and driving motor 11, via inverters 14, 15, HSG 13 and driving motor 11 It may further include a high voltage DC-DC converter (HDC) 19 disposed between the battery 18 and the battery 18 and the inverter 15 connected to the charging and discharging.

In the hybrid system described above, a clutch 13 is provided between the engine 10 and the driving motor 11 so that the engine 11 and the driving motor 11 can selectively assist power. That is, in the state in which the clutch 12 is connected, the driving force of the engine 10 and the driving motor 11 is transmitted to the wheel 17 via the transmission 16 (HEV mode), and the clutch 12 is released. In a state in which the power of the engine 10 is cut off, only the driving force of the driving motor 11 is transmitted to the wheel W through the transmission 16 by the electric power charged in the battery 18 (EV mode). In the HEV (Hybrid Electric Vehicle) mode or EV (Electric Vehicle) mode, the power stored in the battery 18 is supplied to the driving motor 11 through the inverter 15 .

Meanwhile, the HSG 13 is a motor that integrates the functions of a starter motor and a generator, and is a motor integrated between the engine 10 and the drive motor 11 , and more specifically, between the engine 10 and the clutch 12 . It is installed on the power shaft and has a structure directly connected to the engine, and has a structure in which the rotation shaft of the engine 10 and the rotation shaft of the HSG 13 are connected to form an integral shaft. The engine 10 is connected to the HSG 13 through a belt (not shown), and serves to start the engine 10 or charge the battery 18 while rotating by the engine 10 .

The HCU 20 includes the engine 10 and the driving motor to output distributed power (torque) based on the driving information detected from the driving information detecting unit 21 and the information on the charge amount (SOC) of the battery 18 . A power distribution signal for controlling (11), that is, an engine torque command and a motor torque command, is transmitted to the ECU and the MCU (Motor Control Unit), respectively.

In the battery 18, an electrothermal electric load 22a such as a heated seat, a heated handle, a PTC heater, a headlamp, and an air conditioning electric load 22b such as a blower, a defroster, and a compressor, and a cooling fan, EWP ( An electrical load 22c to relieve a thermal load such as an Electronic Water Pump motor) is connected and is driven by the power supplied from the battery 18 .

The driving information detection unit 21 is composed of a plurality of sensors attached to the vehicle, and collects information related to vehicle driving, such as atmospheric pressure (inferring vehicle altitude), vehicle speed, acceleration, accelerator pedal effort, and the vehicle's driving path, and collects the (20) is provided.

2 is a flowchart illustrating a reverse series control method for improving fuel efficiency of a hybrid vehicle according to a preferred embodiment of the present invention.

As shown in FIG. 2 , first, the HCU 20 stops regenerative braking for protection of the high voltage battery 18 , and determines whether it is necessary to switch the driving mode from the EV mode to the HEV mode. . In a conventional hybrid vehicle, when the EV mode is performed for a long time and the high voltage battery 18 is charged over a certain amount of charge, regenerative braking and charging of the battery are stopped to prevent damage to the battery due to excessive charging. At this time, in order to maintain the degree of deceleration in the regenerative braking situation, the EV mode is released, the HEV mode is started, and the deceleration is maintained using the engine brake. Therefore, in order to first determine whether it is necessary to stop regenerative braking and battery charging for battery protection, the HCU 20 determines whether the charge amount SOC of the high voltage battery 18 is equal to or greater than a predetermined first reference value. (S10).

When it is determined in step S10 that the amount of charge SOC of the high voltage battery 18 is equal to or greater than a predetermined first reference value, it is determined that regenerative braking and charging of the battery need to be stopped to protect the battery. However, as in the prior art, when regenerative braking and battery charging are stopped for battery protection, the EV mode is released and the HEV mode is started. At this time, when the vehicle is accelerated, the engine 10 was unnecessary in the EV mode. fuel supply to the Accordingly, there is a problem that fuel efficiency is lowered. Therefore, in the preferred embodiment according to the present invention, instead of changing the driving mode for battery protection, reverse-series control is performed (S50).

In a typical hybrid vehicle, series control is performed. In series control, power is generated and transmitted in the following order: engine operation (fuel consumption) -> HSG power generation (power generation mode) -> electric energy generation -> motor drive -> vehicle drive (conversion of electric energy into kinetic energy). On the other hand, in the reverse series control method according to the present invention, in the order of vehicle braking (kinetic energy generation) -> motor generation (regenerative braking) -> electric energy generation -> HSG driving (starter mode) -> engine rotation, power is generated and passed That is, in the reverse series control according to the present invention, the HSG 13 is driven with the electric energy generated by the regenerative braking without stopping the regenerative braking, and the engine 10 is forcibly rotated in the starter mode without fuel consumption. make it Through this, by forcibly consuming the electric energy generated by the regenerative braking and charged in the high voltage battery 18, the regenerative braking is maintained without changing the driving mode, thereby preventing unnecessary fuel consumption. In addition, by performing the natural regeneration of the GPF and the EMM at an early stage, it is possible to achieve an additional fuel efficiency increase effect.

On the other hand, even when it is determined that the charge amount (SOC) of the high voltage battery 18 is less than the first predetermined reference value in step S10, and there is no need to immediately perform the reverse series control for battery protection, the regenerative agent under a predetermined condition By predicting the same amount, it is more preferable to preemptively consume the charge amount SOC of the high voltage battery 18 .

To this end, when the charge amount SOC of the high voltage battery 18 is less than a predetermined first reference value, the HCU 20 determines whether it is equal to or greater than a second reference value smaller than the first reference value (S20). When the charge amount (SOC) of the high voltage battery 18 is equal to or greater than the second reference value, it is not necessary to immediately perform reverse series control, but depending on the expected amount of regenerative braking, the charge amount required for reverse series control may be reached in a short time. However, it is judged that it is necessary to preemptively perform reverse series control.

Therefore, when it is determined in step S20 that the charge amount (SOC) of the high voltage battery 18 is less than the first predetermined reference value and greater than or equal to the second reference value, in order to determine whether it is necessary to preemptively perform the reverse series control. , the expected amount of regenerative braking is predicted ( S30 ). Then, it is determined whether the expected regenerative braking amount is equal to or greater than a predetermined reference value (S40), and when the expected regenerative braking amount is greater than or equal to a predetermined reference value, the reverse series control is preemptively performed (S50).

In this case, the expected amount of regenerative braking may be preferably predicted through the amount of change in the charge amount of the high voltage battery 18 , atmospheric pressure, vehicle speed and acceleration, accelerator pedal effort, and navigation path. For example, information on the slope of the road on which the vehicle is driving may be acquired through navigation route information, altitude information of the road on which the vehicle is driving, such as atmospheric pressure, and a 3-axis acceleration sensor. Through this information, when it is determined that the vehicle is currently traveling on a downhill road of a predetermined angle or more and it is determined that the downhill road continues for more than a certain amount, it may be determined that the expected amount of regenerative braking for performing the reverse series control is satisfied. Similarly, through the charge amount detection sensor of the battery 18, information on the amount of change in the amount of charge of the battery 18 is obtained, and when the amount of charge increases faster than a certain speed, the expected amount of regenerative braking for performing the reverse series control can be considered to be satisfied. Also, in the same way, using the relationship between the vehicle speed and vehicle acceleration (or the pedal effort of the accelerator pedal) and the amount of regenerative braking, it is determined whether the expected amount of regenerative braking for performing reverse series control is satisfied from the information of the vehicle speed and vehicle acceleration. can

On the other hand, only by forcibly rotating the engine 10 by the HSG 13 by performing the reverse series control, the charge amount of the battery 18 may not be sufficiently consumed. In this case, it is necessary to forcibly drive a separate electric load to additionally consume the charge amount of the battery 18 .

To this end, the HCU 20 calculates the current charge consumption of the high voltage battery 18 during reverse series control through a battery charge amount detection sensor (not shown) (S60). Then, the amount of charging consumption per hour is compared with a predetermined reference value (S70). When the amount of charge consumption per hour is less than a predetermined reference value in step S70, it is determined that a sufficient amount of charge for battery protection is not consumed. Accordingly, the HCU 20 forcibly drives the electric load connected to the battery 18 (S80). As shown in FIG. 1 , the electric load connected to the battery 18 includes an electrothermal electric load 22a such as a heated seat, a heated handle, a PTC heater, and a head lamp, and an air conditioner such as a blower, a defroster, and a compressor. There is an electric load 22b, a cooling fan, and an electric load 22c to relieve a thermal load such as an electronic water pump motor (EWP). At least one of the electrothermal electric load 22a, the air conditioning electric load 22b, and the thermal load relief electric load 22c is forcibly driven to quickly consume the charge amount of the high voltage battery 18 .

As described above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto, and the technical spirit of the present invention and the following by those of ordinary skill in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

10: engine 11: drive motor
12: clutch 13: HCG
14: inverter 15: inverter
16: transmission 17: wheel
18: battery 19: HDC
20: HCU 21: operation information detection unit
22a: electrothermal electrical load 22b: air conditioning electrical load
22c: thermal load relief electrical load

Claims (8)

determining whether it is necessary to stop regenerative braking for high voltage battery protection; and
When it is determined that it is necessary to stop regenerative braking, the reverse-series consumes the charge amount of the high-voltage battery by forcibly rotating the engine by means of a hybrid starter and generator (HSG) in a state where the fuel supply to the engine is stopped. ) A reverse series control method for improving fuel efficiency of a hybrid vehicle, characterized in that the control is performed. The method according to claim 1,
In the step of determining whether it is necessary to stop the regenerative braking,
and determining that regenerative braking needs to be stopped to protect the high voltage battery when the charge amount of the high voltage battery is equal to or greater than a first reference value. 3. The method according to claim 2,
In the step of determining whether it is necessary to stop the regenerative braking,
determining whether the amount of charge of the high voltage battery is equal to or greater than a second reference value when the amount of charge of the high voltage battery is less than a first reference value;
predicting an expected amount of regenerative braking from the driving information detected by the driving information detector when the amount of charge of the high voltage battery is equal to or greater than a second reference value; and
When the calculated expected regenerative braking amount is equal to or greater than a predetermined value, it is determined that regenerative braking needs to be stopped in order to protect a high voltage battery. 4. The method according to claim 3,
A reverse series control method for improving fuel efficiency of a hybrid vehicle, wherein the expected regenerative braking amount is predicted from a current battery charge amount of a high voltage battery and a change amount of the battery charge amount for a predetermined time up to the current time point. 4. The method according to claim 3,
An inverse series control method for improving fuel efficiency of a hybrid vehicle, wherein the expected amount of regenerative braking is predicted from at least one of a current vehicle speed, an acceleration, and an accelerator pedal effort. 4. The method according to claim 3,
A reverse series control method for improving fuel efficiency of a hybrid vehicle, wherein the expected amount of regenerative braking is predicted from at least one of current atmospheric pressure, location and altitude information input from a vehicle navigation system, and information on a slope gradient of a road on which the vehicle is currently traveling. The method according to claim 1,
calculating the amount of charge of the high voltage battery consumed by the inverse series control;
When the charge amount of the high voltage battery consumed by the reverse series control is less than a predetermined value, forcibly operating an additional electric load, the reverse series control method for improving fuel efficiency of a hybrid vehicle. 8. The method of claim 7,
The electrical load is
Electrical load by the electric heating device installed in the vehicle,
electrical load by the air conditioner installed in the vehicle and
A reverse series control method for improving fuel efficiency of a hybrid vehicle, which is at least one of an electric load by a device installed in the vehicle to relieve a thermal load.

Images