KR20160040904A - Method and apparatus for controlling engine start for hybrid electric vehicle - Google Patents

Abstract

The present invention relates to a method and a system for controlling engine starting of a hybrid vehicle.
An engine start control method for a hybrid vehicle according to an embodiment of the present invention includes: determining whether an engine start request is present; Calculating the representative motor acceleration based on the latest n motor accelerations when the engine start request is present; Calculating a first time required for the motor speed at the engine start request time to reach the target speed based on the representative motor acceleration; Calculating a second time required for the engine speed at the engine start time to reach the target speed; Calculating a third time from the first time minus the second time; And determining the engine start time according to the third time.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and an apparatus for controlling an engine start of a hybrid vehicle,

The present invention relates to a hybrid vehicle, and more particularly, to a method and an apparatus for controlling engine starting of a hybrid vehicle.

As is known, a hybrid electric vehicle uses an internal combustion engine together with a battery power source. That is, the hybrid vehicle uses the power of the internal combustion engine and the power of the motor in an efficient combination.

The hybrid vehicle includes an engine, a motor, an engine clutch for controlling power between the engine and the motor, a transmission, a differential gear device, a high-voltage battery, a hybrid starter & generator (HSG) And wheels. The HSG may be referred to as an integrated starter & generator (ISG).

The hybrid vehicle may be an EV mode that uses only the power of the motor to engage or disengage the engine clutch in accordance with acceleration / deceleration will, vehicle speed, state of charge (SOC), etc. of the battery due to operation of the driver's accelerator pedal and brake pedal electric vehicle mode); An HEV mode (hybrid electric vehicle mode) using the power of the engine as the main power and the power of the motor as the auxiliary power; A regenerative braking mode for recovering braking and inertia energy during braking or inertia of the vehicle through power generation of the motor and charging the high voltage battery; And the like.

The hybrid vehicle utilizes both the mechanical energy of the engine and the electric energy of the battery, utilizes the optimal operating region of the engine and the motor, and recovers energy at the time of braking, thereby improving fuel efficiency and utilizing energy efficiently.

When the hybrid vehicle is switched from the EV mode to the HEV mode (i.e., when the engine is started), the engine speed and the motor speed are synchronized and then the engine clutch is engaged. So that the drivability can be ensured by preventing variations.

5 is a graph for explaining a conventional engine start control method.

As shown in FIG. 5, if there is an engine start request at time k, the engine is started and the engine speed is increased to the engine idle speed. When engaging the engine clutch with the motor speed lower than the engine idle speed, the torque fluctuation and engine stall may occur. Therefore, there is a waiting time (invalid engine drive time) that does not engage the engine clutch until the motor speed becomes equal to or higher than the engine idle speed. That is, although the power of the engine is not transmitted during the standby time, there is a problem that the engine is unnecessarily driven and fuel efficiency is lowered.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an engine start control method for a hybrid vehicle, which can improve the fuel consumption by shortening the waiting time when the engine is unnecessarily driven, Device.

An engine start control method for a hybrid vehicle according to an embodiment of the present invention includes: determining whether an engine start request is present; Calculating the representative motor acceleration based on the latest n motor accelerations when the engine start request is present; Calculating a first time required for the motor speed at the engine start request time to reach the target speed based on the representative motor acceleration; Calculating a second time required for the engine speed at the engine start time to reach the target speed; Calculating a third time from the first time minus the second time; And determining the engine start time according to the third time.

Calculating the representative motor acceleration comprises calculating an average motor acceleration based on the n most recent motor accelerations; Calculating a standard deviation based on the n motor accelerations and the average motor acceleration; Calculating a bandwidth based on the average motor acceleration and the standard deviation; And determining a set of weights corresponding to the bandwidth.

의 식으로부터 계산될 수 있다. 여기서, A_{k -n+ 1}는 k-n+i 시점의 모터 가속도이다.The average motor acceleration (MA)

Can be calculated from the following equation. Here, A _{k -n + 1} is the motor acceleration at time k-n + i.

의 식으로부터 계산될 수 있다. 여기서, K는 설정된 계수이고, σ는 상기 표준편차이며, MA는 상기 평균 모터 가속도이다.The above-mentioned Bandwidth may be,

Can be calculated from the following equation. Here, K is a set coefficient,? Is the standard deviation, and MA is the average motor acceleration.

의 식으로부터 계산될 수 있다. 여기서 A_{k -n+i} 는 k-n+i 시점의 모터 가속도이고, W_i 는 i 번째 가중치이다.The representative acceleration may be,

Can be calculated from the following equation. Where A _{k -n + i} is the motor acceleration at time k-n + i, and W _i is the i-th weight.

의 관계식을 만족할 수 있다.Wherein the n weight values are <

Can be satisfied.

The n weight values may change according to the change of the bandwidth.

The sum of the n weights may be one.

The second time may be calculated from a map of the relationship between the engine coolant temperature and the HSG available torque.

The method for controlling engine startup of the hybrid vehicle includes the steps of: starting the engine when the third time period has elapsed from the engine start requesting time; And combining the engine clutch when the first time has elapsed from the engine start requesting time.

An engine start control apparatus for a hybrid vehicle according to an embodiment of the present invention includes: a data detecting section for detecting data for engine start control of the hybrid vehicle; And a control unit for determining whether an engine start request is made based on the data, determining an engine start time, and controlling the engine according to the engine start time, The representative motor acceleration is calculated based on the motor acceleration, and the first time required for the motor speed at the engine start request time to reach the target speed is calculated based on the representative motor acceleration.

The control unit may calculate a second time required for the engine speed at the engine start time to reach the target speed from a map of the relationship between the engine coolant temperature and the HSG available torque.

Wherein the engine start control device of the hybrid vehicle further includes an engine clutch that interrupts power between the engine and the motor, the control unit calculates a third time after subtracting the second time from the first time, The engine is started when the third time elapses from the start request time, and the engine clutch can be engaged when the first time elapses from the engine start request time.

Wherein the control unit calculates an average motor acceleration based on the latest n motor accelerations, calculates a standard deviation based on the n motor accelerations and the average motor acceleration, and based on the average motor acceleration and the standard deviation The bandwidth can be calculated, and a set of weights corresponding to the bandwidth can be determined.

의 식으로부터 계산할 수 있다. 여기서, A_{k -n+ 1}는 k-n+i 시점의 모터 가속도이다.The control unit calculates the average motor acceleration (MA)

Can be calculated from the following equation. Here, A _{k -n + 1} is the motor acceleration at time k-n + i.

의 식으로부터 계산할 수 있다. 여기서, K는 설정된 계수이고, σ는 상기 표준편차이며, MA는 상기 평균 모터 가속도이다.Wherein the control unit sets the bandwidth

Can be calculated from the following equation. Here, K is a set coefficient,? Is the standard deviation, and MA is the average motor acceleration.

의 식으로부터 계산할 수 있다. 여기서 A_{k -n+i} 는 k-n+i 시점의 모터 가속도이고, W_i 는 i 번째 가중치이다.The control unit calculates the representative acceleration

Can be calculated from the following equation. Where A _{k -n + i} is the motor acceleration at time k-n + i, and W _i is the i-th weight.

의 관계식을 만족할 수 있다.Wherein the n weight values are <

Can be satisfied.

The n weight values may change according to the change of the bandwidth.

The sum of the n weights may be one.

As described above, according to the embodiment of the present invention, it is possible to start the engine at the optimum time when there is an engine start request. It is possible to shorten the waiting time (the invalid engine driving time) in which the engine is unnecessarily driven and improve the fuel efficiency of the hybrid vehicle.

1 is a block diagram showing a configuration of a hybrid vehicle according to an embodiment of the present invention.
2 is a flowchart of an engine start control method of a hybrid vehicle according to an embodiment of the present invention.
3 is a view for explaining a set of weights corresponding to the fluctuation width according to the embodiment of the present invention.
4 is a graph for explaining an engine start control method of a hybrid vehicle according to an embodiment of the present invention.
5 is a graph for explaining a conventional engine start control method.

Hereinafter, 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. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms.

In addition, since the components shown in the drawings are arbitrarily shown for convenience of explanation, the present invention is not necessarily limited to those shown in the drawings.

1 is a block diagram showing a configuration of a hybrid vehicle according to an embodiment of the present invention.

1, a hybrid vehicle according to an embodiment of the present invention includes an engine 10, a motor 20, an engine clutch 30 for interrupting power between the engine 10 and the motor 20, The differential gear device 70, the wheel 80, the data detecting section 90, and the power generating section 40, the battery 50, the HSG 60 that starts up the engine 10 or is generated by the output of the engine 10, And a control unit (100).

The power transmission of the hybrid vehicle is such that the power generated by the engine 10 and the motor 20 is selectively transmitted to the input shaft of the transmission 40 and the power output from the output end of the transmission 40 is transmitted to the differential gear device 70 To the axle. The hybrid vehicle is driven by the power generated by the engine 10 or the motor 20 by rotating the wheel 80 with the axle.

The battery 50 stores the high voltage and can supply the driving voltage to the motor 20 in the EV mode and the HEV mode and can be charged through the electricity recovered through the motor 20 in the regenerative braking mode.

The control unit 100 controls the output torque of the engine 10 and the motor 20 in accordance with the state of the hybrid vehicle and controls the output torque of the engine 10 and the motor 20 according to the operating condition and the state of charge of the battery 50 And drives the hybrid vehicle in the HEV mode.

The data detection unit 90 detects data for engine start control of the hybrid vehicle, and the data detected by the data detection unit 90 is transmitted to the control unit 100.

The data detection unit 90 includes an accelerator pedal position detection unit 91, a brake pedal position detection unit 92, a vehicle speed detection unit 93, an SOC detection unit 94, a cooling water temperature detection unit 95, and a motor speed detection unit 96 can do.

The accelerator pedal position detection unit 91 measures the position value of the accelerator pedal (the degree to which the accelerator pedal is depressed) and transmits a signal to the control unit 100. When the accelerator pedal is fully depressed, the position value of the accelerator pedal is 100%, and when the accelerator pedal is not depressed, the position value of the accelerator pedal is 0%.

The brake pedal position detection section 92 measures the position value of the brake pedal (the degree to which the brake pedal is depressed) and transmits a signal to the control unit 100. When the brake pedal is fully depressed, the position value of the brake pedal is 100%, and when the brake pedal is not depressed, the position value of the brake pedal is 0%.

The vehicle speed detector 93 detects the vehicle speed and transmits a signal to the control unit 100. [ The vehicle speed detector 93 can be mounted on the wheel 80. [

The SOC detection unit 94 detects the SOC of the battery 50 and transmits a signal to the control unit 100. Instead of directly detecting the SOC of the battery 50, the current and voltage of the battery 50 may be measured and the SOC of the battery 50 may be predicted therefrom.

The cooling water temperature detection unit 95 detects the cooling water temperature of the engine 10 and transmits a signal to the control unit 100.

The motor speed detecting unit 96 detects the motor speed and transmits a signal to the control unit 100. [ The control unit 100 can calculate the motor acceleration by differentiating the motor speed.

The control unit 100 may be implemented by one or more microprocessors operating according to a set program, and the set program may be executed by the ECU 100 executing various steps included in the engine start control method of a hybrid vehicle according to an embodiment of the present invention And the like.

Hereinafter, the engine start control method of the hybrid vehicle will be described in detail with reference to FIG. 2 to FIG.

3 is a view for explaining a set of weights corresponding to the fluctuation width according to the embodiment of the present invention, and Fig. 4 is a view for explaining a method for controlling the engine starting of the hybrid vehicle according to the embodiment of the present invention. Fig. 7 is a graph for explaining an engine start control method of a hybrid vehicle according to an embodiment. Fig.

Referring to FIGS. 2 to 4, a method of controlling engine startup of a hybrid vehicle according to an embodiment of the present invention starts by determining whether there is an engine start request in a state where the engine is stopped (S100). The engine start request includes a case where it is necessary to switch from the EV mode to the HEV mode. For example, the engine start request is not limited thereto, but can be satisfied if the driver's requested power is equal to or greater than a set value. The required power of the driver can be calculated based on the required torque and the vehicle speed, and the set value can be set to a value determined by a person skilled in the art.

If there is no request to start the engine in step S100, the method for controlling engine startup of the hybrid vehicle according to the embodiment of the present invention ends.

)를 계산한다(S110). 즉, 제어 유닛(100)은 현재 시점(k시점) 이후의 모터 속도가 상기 대표 모터 가속도(

)에 따라 변화하는 것으로 판단할 수 있다.If the engine start request is received in step S100, the control unit 100 determines whether or not the representative motor acceleration (

(S110). That is, the control unit 100 determines whether or not the motor speed after the current point of time (k point)

). ≪ / RTI >

)를 계산함으로써 현재 시점(k시점) 이후의 모터 속도를 예측한다.Generally, the motor acceleration is affected by the resultant force of the drive torque and the running resistance. Further, the drive torque is influenced by the torque demanded by the driver, the power limitation of the battery, and the like. Since the required torque of the driver and the road condition etc. continuously change during running of the hybrid vehicle, all driving torques and running resistance after the current point of time (k point) are predicted (for example, using Kalman filter) The error may be large. Therefore, in the embodiment of the present invention, the representative motor acceleration (

) To predict the motor speed after the current time (k time point).

The control unit 100 calculates the average motor acceleration MA based on the n most recent motor accelerations (S111). The control unit 100 can calculate the motor acceleration by differentiating the motor speed detected by the motor speed detection unit 96. [ The average motor acceleration MA can be calculated by the following equation.

Here, A _{k -n + 1} is the motor acceleration at time k-n + i. That is, the control unit 100 can calculate the average motor acceleration MA at the current time point (k point) based on the n most recent motor accelerations A _k to A _{k -n + 1} .

The control unit 100 calculates a standard deviation sigma based on the latest n motor accelerations A _k to A _{k -n + 1} and the average motor acceleration MA in step S112. The control unit 100 may calculate an upper band and a lower band of the motor acceleration based on the average motor acceleration MA and the standard deviation sigma. The upper band and the lower band can be calculated by the following equations.

Here, K can be set to a value that a person skilled in the art judges desirable as a coefficient, and may be 2 for example. If K is 2, the motor acceleration has a value between the upper band and the lower band at a probability of 95.5%.

The control unit 100 calculates a bandwidth based on the average motor acceleration MA and the standard deviation sigma (S113). The bandwidth can be calculated by the following equation.

The Bandwidth is an index indicating how far past motor acceleration is from the average motor acceleration MA. That is, the smaller the bandwidth is, the smaller the driver's required torque and the change in the running resistance are, and the larger the bandwidth is, the greater the change in the driver's required torque and running resistance is.

). (i+1) 번째 가중치를 i번째 가중치 이상으로 함으로써 최근의 모터 가속도가 대표 모터 가속도(

)에 가장 큰 영향을 끼치게 된다.The control unit 100 determines a weight set corresponding to the bandwidth (S114). In one set of weights, n weights W ₁ to W _n may be set. The sum of the n weights may be 1, and the ith weight may be less than or equal to the (i + 1) th weight (i.e.,

). By setting the (i + 1) -th weight to be equal to or greater than the i-th weight, the latest motor acceleration becomes the representative motor acceleration

) Will have the greatest effect.

Also, since a set of weights corresponding to the bandwidth is determined from among a plurality of sets of weights, the weights of the same order may be different from each other in the different sets of weights. That is, the n weight values change according to the change of the bandwidth. As the bandwidth increases, the nth weight (W _n ) applied to the recent motor acceleration increases and the first weight (W ₁ ) applied to the old motor acceleration may decrease.

)를 계산한다(S115). 상기 대표 모터 가속도(

)는 다음의 식에 의하여 계산될 수 있다.The control unit 100 calculates the representative motor acceleration (A _k ) based on the latest n motor accelerations A _k to A _{kn +1} and the determined weight set

(S115). The representative motor acceleration (

) Can be calculated by the following equation.

Where A _{k -n + i} is the motor acceleration at time k-n + i, and W _i is the i-th weight.

)를 기초로 엔진 기동 요구 시점(k 시점)의 모터 속도(Motspd_k)가 목표 속도(Motspd_Tgt)에 도달하는데 소요되는 제1 시간(T₁)을 계산한다(S120). 즉, 상기 제1 시간(T₁)은 다음의 식에 의하여 계산될 수 있다.The control unit (100)

A first time T ₁ required for the motor speed Motspd _k at the engine start requesting time point k to reach the target speed Motspd _Tgt is calculated at step S120. That is, the first time T ₁ may be calculated by the following equation.

Here, the target speed (Motspd _Tgt ) may be the engine idle speed.

The control unit 100 calculates a second time T ₂ required for the engine speed at the engine start time to reach the target speed Motspd _Tgt at step S130. That is, the second time T ₂ is the time required for the engine to start and reach the engine idle speed while the engine is stopped. The second time T ₂ varies depending on the engine coolant temperature and the available HSG torque. The HSG usable torque varies with the SOC of the battery 50 as the maximum torque that the HSG 60 can output. Therefore, the control unit 100 can calculate the second time T ₂ from the map of the relationship between the engine coolant temperature and the HSG usable torque. The map can be set in advance through an iterative experiment.

Steps S111 through S120 and S130 may be performed separately or simultaneously.

Thereafter, the control unit 100 calculates a third time T ₃ by subtracting the second time T ₂ from the first time T ₁ (S 140).

The control unit 100 determines the engine start point in accordance with the third time (T ₃₎ (S150). In other words, when said third time (T ₃₎ has elapsed from the engine start-up required time (time k), the control unit 100 can start the engine (10) (S160). Thereafter, the control unit 100 may engage the engine clutch 30 when the first time (T ₁ ) elapses from the engine start requesting time.

As described above, according to the embodiment of the present invention, it is possible to start the engine at the optimum time when there is an engine start request. It is possible to shorten the waiting time (the invalid engine driving time) in which the engine is unnecessarily driven and improve the fuel efficiency of the hybrid vehicle.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

10: engine 20: motor
30: engine clutch 40: transmission
50: Battery 60: HSG
70: Differential gear device 80: Wheel
90: Data detecting unit 100: Control unit

Claims (20)

Determining whether an engine start request is present;
Calculating the representative motor acceleration based on the latest n motor accelerations when the engine start request is present;
Calculating a first time required for the motor speed at the engine start request time to reach the target speed based on the representative motor acceleration;
Calculating a second time required for the engine speed at the engine start time to reach the target speed;
Calculating a third time from the first time minus the second time; And
Determining the engine start time according to the third time;
And a control unit for controlling the engine.
The method according to claim 1,
Wherein the step of calculating the representative motor acceleration comprises:
Calculating an average motor acceleration based on the n most recent motor accelerations;
Calculating a standard deviation based on the n motor accelerations and the average motor acceleration;
Calculating a bandwidth based on the average motor acceleration and the standard deviation; And
Determining a set of weights corresponding to the bandwidth;
And a control unit for controlling the engine.
3. The method of claim 2,
The average motor acceleration (MA)

Of the engine is calculated from the following formula: < EMI ID = 1.0 >
Here, A _{k -n + 1} is the motor acceleration at time k-n + i.
3. The method of claim 2,
The above-mentioned Bandwidth may be,

Of the engine is calculated from the following formula: < EMI ID = 1.0 >
Here, K is a set coefficient,? Is the standard deviation, and MA is the average motor acceleration.
3. The method of claim 2,
The representative acceleration may be,

Of the engine is calculated from the following formula: < EMI ID = 1.0 >
Where A _{k -n + i} is the motor acceleration at time k-n + i, and W _i is the i-th weight.
6. The method of claim 5,
Wherein the n weight values are <

Of the engine (1).
6. The method of claim 5,
Wherein the n weighting values change according to a change in the bandwidth of the engine.
6. The method of claim 5,
Wherein the sum of the n weight values is one.
The method according to claim 1,
Wherein the second time is calculated from a map of the relationship between the engine coolant temperature and the HSG available torque.
The method according to claim 1,
Activating the engine when the third time period elapses from the engine start requesting time; And
Combining the engine clutch when the first time period elapses from the engine start requesting time;
Further comprising the steps of:
1. An engine starting control apparatus for a hybrid vehicle including an engine and a motor,
A data detector for detecting data for engine start control of the hybrid vehicle;
A control unit for determining whether an engine start request is present based on the data, determining an engine start time, and controlling the engine according to the engine start time;
≪ / RTI >
Wherein the control unit calculates a representative motor acceleration based on the latest n motor accelerations when there is the engine start request and calculates a first motor speed at which the motor speed at the engine start request point reaches the target speed based on the representative motor acceleration, Of the engine (1).
12. The method of claim 11,
Wherein the control unit calculates a second time required for the engine speed at the engine starting time to reach the target speed from a map of the relationship between the engine coolant temperature and the HSG available torque .
13. The method of claim 12,
Further comprising an engine clutch for interrupting power between the engine and the motor,
Wherein the control unit calculates a third time obtained by subtracting the second time from the first time and activates the engine when the third time elapses from the engine start requesting time, And when the time elapses, engages the engine clutch.
12. The method of claim 11,
Wherein the control unit calculates an average motor acceleration based on the latest n motor accelerations, calculates a standard deviation based on the n motor accelerations and the average motor acceleration, and based on the average motor acceleration and the standard deviation Calculates a bandwidth, and determines a set of weights corresponding to the bandwidth.
15. The method of claim 14,
Wherein the control unit comprises:
The average motor acceleration (MA)

The engine starting control device of the hybrid vehicle.
Here, A _{k -n + 1} is the motor acceleration at time k-n + i.
15. The method of claim 14,
Wherein the control unit comprises:
The above-mentioned bandwidth

The engine starting control device of the hybrid vehicle.
Here, K is a set coefficient,? Is the standard deviation, and MA is the average motor acceleration.
15. The method of claim 14,
Wherein the control unit comprises:
The representative acceleration

The engine starting control device of the hybrid vehicle.
Where A _{k -n + i} is the motor acceleration at time k-n + i, and W _i is the i-th weight.
18. The method of claim 17,
Wherein the n weight values are <

Of the engine (1).
18. The method of claim 17,
And the n weighting values change according to a change in the bandwidth.
18. The method of claim 17,
Wherein the sum of the n weight values is one.

Images