KR20110054983A - Regenerated torque control method of electric vehicle - Google Patents

Abstract

PURPOSE: A regenerated torque control method of an electric vehicle is provided to prevent a vehicle from being slipped and pushed when the vehicle starts on an inclined slope. CONSTITUTION: A regenerative braking torque map is dualized into a clip regeneration torque diagram and a cost regeneration torque diagram. The clip regeneration torque diagram and the cost regeneration torque diagram are dualized into a torque diagram for regeneration and a torque diagram for mount. The cost regeneration torque diagram maintains the maximum cost regeneration torque value. The clip regeneration torque diagram is made of a first regeneration torque diagram and a first mount regeneration torque diagram. The cost regeneration torque diagram is made of a second regeneration torque diagram and a second mount regeneration torque diagram.

Description

 Regenerative torque control method of electric vehicle {REGENERATED TORQUE CONTROL METHOD OF ELECTRIC VEHICLE}

The present invention relates to a regenerative torque control method for an electric vehicle. More particularly, when the accelerator pedal of the vehicle is released, the recovery rate of the regenerative braking can be increased by regenerative braking to maintain fuel deceleration and improve fuel efficiency. A regenerative torque control method for an electric vehicle.

In recent years, in response to the demand for improving fuel economy and developing environmentally friendly products, research on electric vehicles such as hybrid vehicles and fuel cell vehicles has been actively conducted.

An electric vehicle is essentially equipped with a high voltage battery (main battery) that provides the driving power of the electric motor, and the high voltage battery repeatedly supplies the necessary power while charging / discharging the vehicle.

For example, in an electric vehicle, a high voltage battery supplies (discharges) electric energy when driving an electric motor, and stores electric energy by regenerative braking of a motor when driving an engine such as a regenerative braking lamp when driving downhill or when braking ( Charge). Therefore, since the energy of the battery is recovered through the motor of the electric vehicle, efficient use of energy is possible.

Such an electric vehicle may separately include a regenerative braking map for when the brake pedal is pressed (brake switch on), calculate the regenerative braking torque according to the brake operation, and recover the energy of the vehicle.

However, when the electric vehicle runs at a vehicle speed of a certain speed or more (for example, 20 km / h), regenerative braking due to deceleration generated when the accelerator pedal is not held down (excel switch off) is not performed.

The present invention is to overcome the above-mentioned problems, the object of the present invention is to maintain the deceleration when the vehicle releases the accelerator pedal, while at the same time to increase the energy recovery rate by regenerative braking with the constant regenerative torque to improve fuel efficiency. The present invention provides a control method for regenerative torque of an electric vehicle.

In addition, another object of the present invention is to dualize the torque calculation to follow the regenerative torque diagram and the climbing torque diagram, respectively, according to the operation of the brake, thereby effectively preventing vehicle slippage at the start of the ramp while increasing the energy recovery rate during regenerative braking. The present invention provides a control method for regenerative torque of an electric vehicle.

In order to achieve the above object, the regenerative torque control method of the electric vehicle according to the present invention is provided with a creep regenerative torque diagram and creep performance applied when the driver presses or releases the brake pedal when the regenerative braking torque map is turned on. If the brake switch is turned on when the creep regenerative torque diagram is applied and the creep performance is turned off, or the brake operating depth becomes greater than the depth of the first zero threshold, the driver recognizes that the user presses the brake pedal. And comparing the vehicle speed with a predetermined cust speed, and when the vehicle speed is greater than the cust speed, calculates a registrar regenerative torque through the custard regenerative torque diagram, and applies the cust to the vehicle. The regenerative torque calculating step may be included.

When the creep performance is turned off, when the brake switch is turned on or the brake operation depth becomes smaller than the depth of the second zero threshold, the driver recognizes that the brake pedal is released, and the vehicle speed is compared with the preset speed. In addition, when it is larger than the cust speed, the crest regenerative torque may be calculated and applied to the vehicle through the crest regenerative torque diagram.

When the creep performance is turned off, when the brake switch is turned off or the brake pedal is released, when the Excel switch is turned off, the cursed regenerative torque can be calculated and applied to the vehicle through the cursed regenerative torque diagram. have.

If the brake switch is turned on when the creep performance is turned on, or if the brake operating depth becomes larger than the depth of the first zero threshold point, the set speed comparison step of comparing the vehicle speed with a preset set speed and the vehicle speed When the speed is greater than the set speed, the driver may recognize that the driver presses the brake pedal to calculate a regenerative torque through the creep regenerative torque diagram, and may include a regenerative torque calculating step applied to the vehicle.

If the brake switch is turned on when the creep performance is turned on, or if the brake operating depth becomes smaller than the depth of the second zero threshold, a reset speed comparing step of comparing the vehicle speed with a preset reset speed and the vehicle speed may be When it is smaller than the reset speed, the driver may recognize that the brake pedal is released, and calculate the climbing torque through the creep regenerative torque diagram, and may include calculating the climbing torque applied to the vehicle.

The depth of the second zero threshold may be set to be relatively larger than the depth of the first zero threshold.

The regenerative torque control method of the electric vehicle according to the present invention can maintain the deceleration when releasing the accelerator pedal of the vehicle, and increase the energy recovery rate by regenerative braking with the constant regenerative torque to improve fuel efficiency.

In addition, the regenerative torque control method of the electric vehicle according to the present invention dualizes the torque calculation to follow the regenerative torque diagram and the climbing torque diagram according to the operation of the brake, thereby increasing the energy recovery rate at the time of regenerative braking and starting the ramp. It is possible to effectively prevent vehicle jungle.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

1, one embodiment of the regenerative braking torque map of the present invention is shown.

As shown in FIG. 1, the regenerative braking torque map is a creep regenerative torque diagram applied when creep torque is generated and a cursted regenerative torque diagram applied when the cresting torque is generated according to whether creep torque can be generated. It can be seen that it is dualized. In addition, the creep regenerative torque diagram and the cursed regenerative torque diagram are used for the back regenerative torque diagram applied when the driver presses the brake pedal and the back pedal applied when the driver releases the brake pedal to calculate the torque value according to the brake operating depth. It can be seen that the torque diagram is dualized again.

That is, the creep regenerative torque diagram is composed of a first lead torque line applied when the driver presses the brake pedal and a first back torque diagram applied when the driver releases the brake pedal. In addition, the registrar regenerative torque diagram is composed of a second lead torque line applied when the driver presses the brake pedal and a second climb torque diagram applied when the driver releases the brake pedal.

The determination of whether the creep torque can be generated determines that creep regeneration torque of the vehicle can be generated when the speed of the vehicle is maintained at a low speed of less than 10 km when the brake and the excel of the vehicle are turned off. In this case, the maximum creep torque may vary in magnitude (A) in a positive torque state according to the speed of the vehicle.

The torque diagram for the first climbing has a creep torque early when the brake pedal is released (a state in which the brake operating depth is decreased) because the depth of the zero threshold point (Brake Lim_Zor2) is set to a relatively larger value than the torque diagram for the first regeneration. It is to be calculated, and the whole first torque diagram is shifted to the right (in the direction in which the brake operating depth increases) in the figure compared to the torque diagram for the first regen.

On the other hand, in the torque diagram for the first regen, the depth of the zero threshold point (Brake Lim_Zor1) is set to a relatively small value, so that the regenerative torque is calculated early when the driver presses the brake pedal (the brake operating depth increases). The amount of energy recovered through motor generation increases.

In addition, the depth of the zero threshold point, which is the brake operating depth that is switched between the positive and negative torques in the first regen torque diagram, is referred to as the depth of the first zero threshold point (Brake Lim_Zor1), The depth of the zero threshold point, which is the brake operating depth that is switched between positive and negative torques, is referred to as the depth of the second zero threshold point (Brake Lim_Zor2).

That is, the depth Brake Lim_Zor1 of the first zero critical point is a point of time when the torque line for the first regen is reduced, and the depth Brake Lim_Zor2 of the second zero threshold point is a time of increase of the torque line for the first climbing. The depth of the first zero threshold (Brake Lim_Zor1) means when the brake pedal is pressed when the brake switch is turned ON, and the depth of the second zero threshold (Brake Lim_Zor2) is released when the brake pedal is turned OFF. Means when.

In addition, when creep torque is not generated, when the vehicle's excel pedal (excel switch-off) is released, the current regenerative torque, which is the negative torque of the motor that charges the battery for improving fuel efficiency while maintaining a sense of deceleration. Is determined to be generated. In this case, the maximum current regenerative torque may vary in magnitude (B) in a negative torque state according to the speed of the vehicle (eg, 20 km / h or more). The maximum current regenerative torque is the maximum torque that can be charged by the negative torque of the motor when the vehicle travels.

And the registrar regenerative torque diagram is maintained at the maximum registrant torque value if the brake is not operated.

The brake operating depth at which the torque curve for the second climbing starts to increase is referred to as the high critical point depth (Brake Lim_high2). The zero critical point depth Brake Lim_Zor1 of the torque line for the second regen is the same as the zero critical point depth Brake Lim_Zor1 of the torque line for the first regen. The zero critical point depth Brake Lim_Zor2 of the second climbing torque diagram is the same as the zero critical point depth Brake Lim_Zor2 of the first climbing torque diagram and the second zero critical point depth.

The second regen torque diagram is obtained by stepping on the brake pedal at the time when the brake switch is turned on (in a state in which the brake operating depth increases) and when the brake depth (Brake Depth) increases from the first zero threshold point (Brake Lim_Zor1), The torque lead for 2 Reg is reduced. Therefore, when the pedal of the brake is pressed down, the torque is changed as shown in the torque curve for the second reg. As the regenerative torque is added to the regenerative torque, the amount of energy recovered through motor generation increases. .

In addition, the torque diagram for the second back is released when the brake pedal at the time when the brake switch is turned off (the brake operating depth decreases) decreases the brake depth (Brake Depth) below the high threshold depth (Brake Lim_high2). The torque curve for the second climbing is increased until the critical point depth Brake Lim_Zor2 is reached.

Therefore, when the pedal of the brake is released, the torque is increased to the maximum cursor torque and the energy of the negative cursor torque is recovered through motor generation.

In the present invention, when the vehicle's accelerator pedal is released (the accelerator pedal is off), it is possible to maintain a sense of deceleration and increase the energy recovery rate due to regenerative braking by negative torque, which is a negative torque, for improving fuel efficiency.

In addition, according to the present invention, according to whether or not the brake operation is performed in the regenerative torque regenerative torque curve capable of regenerative braking, a separate torque for the brake operation is applied by applying the torque curve for the second back and the torque curve for the second regeneration of the regenerative torque curve. By using the diagram, it is possible to remove the deceleration heterogeneity that can be generated, so that a smooth deceleration feeling can be maintained even when the brake is operated.

In addition, in the present invention, the torque calculation is dualized to follow the regenerative torque map and the climbing torque map, respectively, according to the operation of the brake, thereby increasing the energy recovery rate at the time of regenerative braking and effectively preventing the vehicle from rolling at the start of the slope. .

2, a flowchart illustrating a torque calculation process according to the present invention is shown.

As shown in FIG. 2, the torque calculation process uses the algorithm for recognizing creep performance on and off and stepping on and release of the brake pedal so that the regenerative torque is calculated through the torque diagram corresponding to the creep performance and the brake operation.

First, check whether the shift lever is positioned at the D or R stage (S1), and if the shift lever is positioned at the D or R stage, check whether the creep function is on (S2), When the creep function is turned on, creep torque according to the vehicle speed is calculated (S31). When the creep function is turned off, the current regenerative torque S32 corresponding to the vehicle speed is calculated.

Here, whether the creep function is on or off is determined that the creep function of the vehicle is turned on when the speed of the vehicle is kept at a low speed of less than 10 km when the shift lever is positioned at the D stage or the R stage. If the speed is maintained above 10 km, the creep function is determined to be off.

Then, when the brake switch is turned on or the brake operation depth gradually increases and becomes larger than the depth of the first zero threshold point (Brake Lim_Zor1) (S41), it is determined that Excel is turned off, and the brake operation state When the set speed comparison step (S42) is performed to confirm that the brake is not pressed, the torque map (torque calculation algorithm) according to the accelerator pedal operation amount is called to perform the torque control (S8).

In the set speed comparison step (S42), the current vehicle speed (Vehicle_Speed) is compared with the set speed, which is a preset regen speed. Here, when the vehicle speed is greater than the set speed, the driver presses the brake pedal. In this case, the torque is calculated through the torque line diagram for the first regen of FIG. 1. For example, the set speed may be set in the range of approximately 5-8 km / h.

That is, the torque is calculated through the first regen torque diagram according to the brake operating depth measured by the brake sensor, and is calculated from the time when the depth Brake Lim_Zor1 of the first zero threshold point is detected while following the first regen torque diagram. The negative torque to be becomes the torque for regeneration (the amount of regenerative torque increases as the brake operating depth is increased).

On the other hand, if the brake switch-on condition or the brake operating depth gradually decreases to satisfy the condition smaller than the depth of the second zero threshold point (Brake Lim_Zor2), and the vehicle speed is smaller than the preset climbing speed (Reset Speed), The driver recognizes the situation of releasing the foot while pressing the brake pedal, and in this case, the torque is calculated through the torque diagram for the first climbing of FIG. 1. For example, the reset speed may be set in the range of about 1km to 2km / h.

That is, torque is calculated through the first climbing torque diagram according to the brake operating depth measured by the brake sensor, and is calculated from the time when the depth of the second zero threshold point (Brake Lim_Zor2) is detected while following the climbing torque diagram. The positive torque becomes the torque for climbing (the amount of torque for climbing increases as the brake operating depth decreases).

When the brake regenerative torque S32 is calculated, the brake switch is turned on or the brake operating depth measured by the brake sensor gradually increases to become larger than the depth of the first zero threshold Brake Lim_Zor1 (S43). The driver determines that the driver releases the Excel and depresses the brake pedal, and the speed comparison step S53 is performed in which the vehicle compares the speed with the preset speed. For example, the cust speed may be set to approximately 20 km / h as a speed of the vehicle at which the vehicle may generate a custody torque that is negative torque. That is, when the speed of the vehicle is less than 20 km / h, the current regenerative torque becomes "0".

When the speed of the vehicle is equal to or greater than the cust speed, it is determined that a negative regenerative torque regenerative torque may be generated, and thus, the registrar regenerative torque calculating step S63 for calculating torque by the registrant regenerative torque diagram is performed. Run

That is, the torque is calculated through the second regenerative torque diagram of the registrar regenerative torque diagram according to the brake operating depth measured by the brake sensor (S63), and the depth of the first zero threshold point along the second regenerative torque diagram ( The negative torque calculated from the torque at which Brake Lim_Zor1) is detected becomes the regenerative torque.

On the contrary, after the constant regenerative torque S32 is calculated, the brake operating depth is gradually turned on or the brake operating depth measured by the brake sensor is gradually decreased, so that the depth of the second zero threshold point at the depth of the high threshold Brake Lim_High2 ( When smaller than Brake Lim_Zor2) (S44), it is determined that the driver releases the brake pedal while the driver is releasing the excel, and the speed comparison step (S53) in which the vehicle compares the speed with a preset cust speed is executed. do.

When the speed of the vehicle is equal to or greater than the speed of the vehicle, it is determined that the negative regenerative torque, which is a negative torque, may be generated, and the torque is calculated through the current regenerative torque diagram.

That is, the climbing torque is calculated through the second climbing torque diagram of the current regenerative torque diagram according to the brake operating depth measured by the brake sensor (S63), and the depth of the high critical point along the second climbing torque diagram ( The torque curve for the second climbing which is negative torque increases from the time when the brake Lim_High2) is detected to the time when the depth of the second zero threshold point (Brake Lim_Zor2) is detected. Therefore, when the pedal of the brake is released, the climbing torque increases to the maximum current regis- ter torque, thereby recovering energy of negative torque (-).

If the brake is not pressed after calculating the registrant torque, it is determined whether the accelerator is operated (S7), and when the driver is pressing the accelerator pedal (excel switch on), the torque map according to the accelerator pedal operation amount (torque calculation) Algorithm) to invoke torque control (S8).

On the other hand, if the driver does not step on the brake pedal and the accelerator pedal (excel switch-off) after the calculation of the cust regenerative torque, a cust speed comparison step S53 in which the vehicle compares the speed with a preset cust speed is executed.

When the speed of the vehicle is equal to or greater than the speed of the vehicle, it is determined that the negative regenerative torque, which is a negative torque, may be generated, and the torque is calculated through the current regenerative torque diagram. At this time, since the brake pedal of the vehicle is in an off state and there is no operation separately, the torque is calculated as the constant regenerative torque.

What has been described above is just one embodiment for carrying out the regenerative torque control method of the electric vehicle according to the present invention, and the present invention is not limited to the above-described embodiment, as claimed in the following claims. Without departing from the gist of the invention, anyone of ordinary skill in the art to which the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

1 is an embodiment of a regenerative braking torque map of the present invention.

2 is a flowchart illustrating a torque calculation process according to the present invention.

Claims (6)

The regenerative braking torque map has a creep regenerative torque diagram applied when the driver presses or releases the brake pedal when the creep performance is turned on and a cursed regenerative torque diagram applied when the creep performance is turned off, When the creep performance is turned off, when the brake switch is turned on or when the brake operating depth becomes larger than the depth of the first zero threshold, the driver recognizes that the user presses the brake pedal and compares the vehicle speed with a preset cust speed. A speed comparison step; And If the vehicle speed is greater than the cust speed, calculating a regenerative regenerative torque through the registrar regenerative torque diagram, and calculating a regenerative regenerative torque applied to the vehicle. Torque control method. The method according to claim 1, When the creep performance is turned off, when the brake switch is turned on or the brake operation depth becomes smaller than the depth of the second zero threshold, the driver recognizes that the brake pedal is released, and the vehicle speed is compared with the preset speed. And regulating the registrar regenerative torque through the registrant regenerative torque diagram and applying the same to the vehicle when the regenerative torque curve is greater than the cust speed. The method according to claim 1, When the creep performance is off, When the excel switch is turned off when the brake switch is turned off or the brake pedal is released, the regenerative torque of the electric vehicle is calculated and applied to the vehicle by calculating the cursed regenerative torque through the cursed regenerative torque diagram. Control method. The method according to claim 1, When the creep performance is turned on A set speed comparing step of comparing the vehicle speed with a preset set speed when the brake switch is turned on or when the brake operating depth becomes larger than the depth of the first zero threshold point; And If the vehicle speed is greater than the set speed, the driver is recognized as a step on the brake pedal to calculate the regenerative torque through the creep regenerative torque diagram, comprising the step of calculating the regenerative torque applied to the vehicle A regenerative torque control method for an electric vehicle. The method according to claim 1, When the creep performance is turned on A reset speed comparing step of comparing the vehicle speed with a preset reset speed when the brake switch is turned on or when the brake operating depth becomes smaller than the depth of the second zero threshold point; And And when the vehicle speed is smaller than the reset speed, a driver releases the brake pedal, calculates the torque for climbing using the creep regenerative torque diagram, and calculates a torque for climbing applied to the vehicle. Regenerative torque control method for an electric vehicle, characterized in that. The method according to claim 1, And a depth of the second zero critical point is set to be larger than a depth of the first zero critical point.

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