Range extender start-stop control method and control system and vehicle

Abstract

The invention discloses a range extender start-stop control method and system and a vehicle, and belongs to the field of hybrid vehicle control. According to the technical scheme, the start-stop control method for the range extender comprises the following steps that the power of a generator is dispersed into N power points from zero to the maximum generated power, and a generated power sequence of the range extender is established; obtaining a lowest fuel consumption power sequence of the range extender under the corresponding power generation power; further obtaining a battery net power sequence, and obtaining an internal resistance consumption power sequence by combining the battery internal resistance and the open-circuit voltage; the total power consumption is obtained through the battery total power sequence and the minimum fuel consumption power sequence, and a range extender starting / stopping command is determined through the total power consumption. The method has the beneficial effects that the total minimum equivalent energy consumption of the range extender and the battery is calculated on line in real time through the vehicle control unit in the vehicle running process to judge whether the engine is started or stopped, complex calibration is not needed, and the good oil saving effect is achieved.

Description

Technical Field

[0001] The present invention relates to the field of hybrid vehicle control, and in particular to a range extender start-stop control method, a range extender start-stop control system, and a vehicle. Background Art

[0002] The auxiliary unit consisting of the extended-range hybrid vehicle engine and the ISG motor is also called a range extender. There is no mechanical connection between the range extender and the electric drive system and it is only used for power generation. Therefore, the engine speed / torque and the wheel end are completely decoupled. It can always operate in the high-efficiency zone and has good fuel economy.

[0003] When the range extender is shut down, the vehicle enters the pure electric driving state, and the electric energy required by the electric drive system comes entirely from the power battery; when the range extender is working, if the power generated by the range extender is lower than the power required by the electric drive system, the power battery discharges; if the power generated by the range extender is equal to the power required by the electric drive system, the power battery neither discharges nor charges; if the power generated by the range extender is higher than the power required by the electric drive system, the power battery charges. The timing control of engine start and stop has a great impact on vehicle power and fuel economy.

[0004] Under the current rule-based energy management strategy, the start and stop of the range extender of the extended-range hybrid vehicle is generally determined by the battery SOC and / or vehicle speed and / or required power, such as when the SOC is lower than a certain value and / or the vehicle speed is higher than a certain value and / or the required power is greater than a certain value, the range extender starts to generate electricity; when the SOC is higher than a certain value and / or the vehicle speed is lower than a certain value and / or the required power is lower than a certain value, the range extender stops. The above variable thresholds can only be calibrated in large quantities under different driving and road conditions, and it is impossible to accurately and quantitatively calculate when the engine starts and when it stops. Summary of the invention

[0005] The present invention aims to solve the problem that the start and stop of a range extender are currently determined by a large amount of calibration data and cannot be controlled in real time, and provides a start and stop control method for a range extender.

[0006] To achieve the above object, the technical solution adopted by the present invention is a range extender start-stop control method, comprising the following steps: S1. Calculate the mechanical power required for vehicle driving according to the depth of the driver's accelerator pedal; S2. Obtain the vehicle driving required electric power P based on the required mechanical power and the driving efficiency of the electric drive assembly dem ; S3. Discretize the generator power from zero to the maximum power generation into N power points, and establish the range extender power generation power sequence P APU ; S4. Power sequence P generated by range extender APU, the range extender's lowest specific fuel consumption sequence under the corresponding power generation and the fuel's lower calorific value, and the lowest fuel consumption power sequence P under the range extender's corresponding power generation is obtained fuel,APU ; S5. Based on the vehicle driving demand electric power P in S2 dem and the range extender power sequence P APU , get the battery net power sequence P bat,net , combined with the battery internal resistance and open circuit voltage, the internal resistance power consumption sequence P is obtained bat,res .

[0007] S6. Net power sequence P through the battery bat,net and the minimum fuel consumption power sequence P fuel,APU The total power consumption is obtained, and the start / stop command of the range extender is determined according to the total power consumption.

[0008] Preferably, in step S3, the range extender power generation sequence P APU = [0, P 1,APU , P 2,APU , P 3,APU , …P N,APU ], where P N,APU is the maximum power generation power of the range extender; In step S4, the minimum specific fuel consumption is obtained through the engine universal characteristics and the generator efficiency map. The minimum specific fuel consumption sequence is: BSFC APU = [0, bsfc1, bsfc2, … bsfc N ]; Based on the range extender power generation power sequence P APU and the lowest specific fuel consumption sequence is BSFC APU Get the minimum fuel consumption rate sequence FC APU =P APU * BSFC APU ; Minimum fuel consumption power sequence P fuel,APU = Hu * FC APU / 3600, the lower calorific value of fuel oil is Hu.

[0009] Preferably, the battery net power sequence is: P bat,net = [0, P dem -P 1,APU , P dem – P 2,APU , P dem – P 3,APU , … P dem – P N,APU ]; The internal resistance of the battery is R, and the open circuit voltage is Voc. The internal resistance power consumption sequence of the battery at different net powers is P bat,res for: I =

[0010] P bat,res = ; The total battery power sequence is P bat,total =P bat,net + P bat,res .

[0011] Preferably, in step S5, an oil-to-electricity conversion equivalent factor Eq is obtained based on the battery SOC; In step S6, the total equivalent energy consumption function H of "range extender + battery" is defined, and the total equivalent energy consumption of "range extender + battery" is the total power energy consumption: H = P fuel,APU + Eq * P bat,total Solve the minimum value Hmin of the H function and its corresponding range extender power P opt,APU ; If P opt,APU If it is equal to 0, the range extender will start the original request Run req,raw Set to 0, the range extender is shut down; If P opt,APU If it is greater than 0, the range extender will start the original request Run req,raw Set to 1 to start the range extender.

[0012] Preferably, Eq is calibrated according to SOC.

[0013] Preferably, the SOC is made to approach the target SOC by adjusting Eq through PID: Eq = f(SOC).

[0014] Preferably, the original start request of the range extender is subjected to anti-shake processing, and a final engine start / stop command is output.

[0015] Preferably, the anti-shake time is determined by calibration.

[0016] On the other hand, the present invention further provides a range extender start-stop control system, which is used to execute the above-mentioned range extender start-stop control method, comprising: A power calculation module, used to calculate the mechanical power required for vehicle driving according to the driver's accelerator pedal depth; The electric power conversion module is used to obtain the vehicle driving required electric power P according to the required mechanical power and the driving efficiency of the electric drive assembly. dem ; The first sequence building module is used to discretize the generator power from zero to the maximum power generation into N power points, and establish the range extender power generation power sequence P APU ; The second sequence building module is used to generate power sequence P through the range extender APU , the range extender's lowest specific fuel consumption sequence under the corresponding power generation and the fuel's lower calorific value, and the lowest fuel consumption power sequence P under the range extender's corresponding power generation is obtained fuel,APU ; The third sequence building module is used to generate the electric power P required by the vehicle in S2. dem and the range extender power sequence P APU , get the battery net power sequence P bat,net , combined with the battery internal resistance and open circuit voltage, the internal resistance power consumption sequence P is obtained bat,res ; Sequence analysis module, used to sequence the battery net power P bat,net and the minimum fuel consumption power sequence P fuel,APU The total power consumption is obtained, and the start / stop command of the range extender is determined according to the total power consumption.

[0017] In a third aspect, the present invention further provides a vehicle that adopts the above-mentioned range extender start-stop control method.

[0018] It can be seen from the above technical scheme that the advantages of the present invention are: this scheme determines whether the engine is started / stopped by calculating the total minimum equivalent energy consumption of "range extender + battery" in real time online for the vehicle controller during vehicle driving. It does not require complex calibration and has a good fuel-saving effect. The start and stop of the range extender is determined according to the real-time driving status, and the start and stop instructions are more adapted to actual needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 This is a flow chart of a method according to Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in this specific embodiment. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent.

[0022] Embodiment 1 like Figure 1 As shown, a range extender start-stop control method includes the following steps: S1: Calculate the mechanical power required for vehicle driving according to the depth of the driver's accelerator pedal.

[0023] S2: Obtain the vehicle driving required electric power P based on the required mechanical power and the driving efficiency of the electric drive assembly dem (Unit: kw), which is the sum of the range extender power and the battery power.

[0024] S3: Discretize the generator power from zero to the maximum power generation into N power points, and establish the range extender power generation power (in kw) sequence: P APU = [0, P 1,APU , P 2,APU , P 3,APU , … P N,APU ], where P N,APU is the maximum power generation of the range extender.

[0025] S4: Based on S3, the sequence of the minimum specific fuel consumption (in g / kwh) of the range extender at the corresponding power generation is given: BSFC APU = [0, bsfc1, bsfc2, … bsfc N ] The specific fuel consumption can be obtained based on the engine universal characteristics and the generator efficiency map.

[0026] S5: Based on S3 and S4, calculate the minimum fuel consumption rate (in g / h) sequence under the corresponding power generation of the range extender: FC APU =P APU * BSFC APU S6: The lower calorific value of the fuel is Hu (in kJ / g), then the sequence of the minimum fuel consumption power (in kw) under the corresponding power generation of the range extender is: P fuel,APU = Hu * FC APU / 3600 S6: Based on the vehicle driving demand electric power P in S2 dem and the range extender power sequence P APU , and get the battery net power sequence: P bat,net = [0, P dem -P 1,APU , P dem – P 2,APU , P dem – P 3,APU , … P dem – P N,APU ] A battery power greater than zero indicates that the battery is being discharged, and a battery power less than zero indicates that the battery is being charged.

[0027] S7: Obtain the battery internal resistance R and open circuit voltage Voc, then the battery internal resistance power consumption sequence under different net powers is: I =

[0028] P bat,res =

[0029] S8: Based on S6 and S7, the total battery power sequence is P bat,total =P bat,net + P bat,res S9: Based on the battery SOC, the oil-electric conversion equivalent factor Eq is obtained. This value represents the fuel power value equivalent to the electric energy per unit power: the larger the Eq, the greater the fuel consumption power equivalent to the battery output per unit power. This value changes with the SOC. The lower the SOC, the larger the equivalent factor, and at this time, it is more inclined to start the range extender to generate electricity and not let the battery discharge; the higher the SOC, the smaller the equivalent factor, and at this time, it is more inclined to let the battery discharge and shut down the range extender. Eq can be calibrated according to the SOC, or the PID can be used to adjust the Eq to make the SOC tend to the target SOC.

[0030] Eq = f(SOC) S10: Define the total equivalent energy consumption function H of "range extender + battery", and solve the minimum value Hmin of H function and its corresponding range extender power P opt,APU H = P fuel,APU + Eq * P bat,total S11: If P opt,APU If it is equal to 0, the range extender will start the original request Run req,raw Set to 0; if P opt,APU If it is greater than 0, the range extender will start the original request Run req,rawSet to 1.

[0031] S12: Anti-shake processing is performed on the original start request of the range extender, the anti-shake time can be calibrated, and the final engine start / stop command is output.

[0032] Embodiment 2 This embodiment further provides a range extender start-stop control system, which is used to execute the range extender start-stop control method provided in the first embodiment, including: A power calculation module, used to calculate the mechanical power required for vehicle driving according to the driver's accelerator pedal depth; The electric power conversion module is used to obtain the vehicle driving required electric power P according to the required mechanical power and the driving efficiency of the electric drive assembly. dem ; The first sequence building module is used to discretize the generator power from zero to the maximum power generation into N power points, and establish the range extender power generation power sequence P APU ; The second sequence building module is used to generate power sequence P through the range extender APU , the range extender's lowest specific fuel consumption sequence under the corresponding power generation and the fuel's lower calorific value, and the lowest fuel consumption power sequence P under the range extender's corresponding power generation is obtained fuel,APU ; The third sequence building module is used to generate the electric power P required by the vehicle in S2. dem and the range extender power sequence P APU , get the battery net power sequence P bat,net , combined with the battery internal resistance and open circuit voltage, the internal resistance power consumption sequence P is obtained bat,res ; Sequence analysis module, used to sequence the battery net power P bat,net and the minimum fuel consumption power sequence P fuel,APU The total power consumption is obtained, and the start / stop command of the range extender is determined according to the total power consumption.

[0033] Embodiment 3 Based on the control method provided in the first embodiment, this embodiment further provides a vehicle, and this vehicle adopts the start-stop control method of the range extender in the first embodiment.

[0034] It can be seen from the above implementation modes that the beneficial effect of the present invention is that this scheme determines whether the engine is started / stopped by calculating the total minimum equivalent energy consumption of "range extender + battery" of the vehicle controller in real time online during vehicle driving. It has a good fuel-saving effect without the need for complex calibration. The start and stop of the range extender is determined according to the real-time driving status, and the start and stop instructions are more adapted to actual needs.

[0035] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A range extender start-stop control method, characterized in that: The following steps are involved: S1. Calculate the mechanical power required for vehicle driving according to the depth of the driver's accelerator pedal; S2. Obtain the vehicle driving required electric power P based on the required mechanical power and the driving efficiency of the electric drive assembly dem ; S3. Discretize the generator power from zero to the maximum power generation into N power points, and establish the range extender power generation power sequence P APU ; S4. Power sequence P generated by range extender APU , the range extender's lowest specific fuel consumption sequence under the corresponding power generation and the fuel's lower calorific value, and the lowest fuel consumption power sequence P under the range extender's corresponding power generation is obtained fuel,APU ; S5. Based on the vehicle driving demand electric power P in S2 dem and the range extender power sequence P APU , get the battery net power sequence P bat,net , combined with the battery internal resistance and open circuit voltage, the internal resistance power consumption sequence P is obtained bat,res ; S6. Net power sequence P through the battery bat,net and the minimum fuel consumption power sequence P fuel,APU The total power consumption is obtained, and the start / stop command of the range extender is determined according to the total power consumption.

2. The range extender start-stop control method according to claim 1, characterized in that: In step S3, the range extender generates power sequence P APU = [0, P 1,APU , P 2,APU , P 3,APU , … P N,APU ], where P N,APU is the maximum power generation power of the range extender; In step S4, the minimum specific fuel consumption is obtained through the engine universal characteristics and the generator efficiency map. The minimum specific fuel consumption sequence is: BSFC APU = [0, bsfc1, bsfc2, … bsfc N ]; Based on the range extender power generation power sequence P APU and the lowest specific fuel consumption sequence is BSFC APU Get the minimum fuel consumption rate sequence FC APU =P APU * BSFC APU ; Minimum fuel consumption power sequence P fuel,APU = Hu * FC APU / 3600, the lower calorific value of fuel oil is Hu.

3. The range extender start-stop control method according to claim 2, characterized in that: In S5: The battery net power sequence is: P bat,net = [0, P dem - P 1,APU , P dem – P 2,APU , P dem – P 3,APU , … P dem – P N,APU ]; The internal resistance of the battery is R, and the open circuit voltage is Voc. The internal resistance power consumption sequence of the battery at different net powers is P bat,res for: I = P bat,res = ； The total battery power sequence is P bat,total =P bat,net + P bat,res .

4. The range extender start-stop control method according to claim 3, characterized in that: In step S5, based on the battery SOC, an oil-to-electricity conversion equivalent factor Eq is obtained; In step S6, the total equivalent energy consumption function H of "range extender + battery" is defined, and the total equivalent energy consumption of "range extender + battery" is the total power energy consumption: H = P fuel,APU + Eq * P bat,total Solve the minimum value Hmin of the H function and its corresponding range extender power P opt,APU ; If P opt,APU If it is equal to 0, the range extender's original start request is Run req,raw Set to 0, the range extender is shut down; If P opt,APU If it is greater than 0, the range extender will start the original request Run req,raw Set to 1 to start the range extender.

5. The range extender start-stop control method according to claim 4, characterized in that: Eq is calibrated according to SOC.

6. The range extender start-stop control method according to claim 5, characterized in that: The SOC is made to approach the target SOC by adjusting the PID equation: Eq = f(SOC).

7. The range extender start-stop control method according to claim 4, characterized in that: The original start request of the range extender is de-shaked and the final engine start / stop command is output.

8. The range extender start-stop control method according to claim 7, characterized in that: The anti-shake time is determined by calibration.

9. A range extender start-stop control system, characterized in that: The method for starting and stopping a range extender according to any one of claims 1 to 8 comprises: A power calculation module, used to calculate the mechanical power required for vehicle driving according to the driver's accelerator pedal depth; The electric power conversion module is used to obtain the vehicle driving required electric power P according to the required mechanical power and the driving efficiency of the electric drive assembly. dem ; The first sequence building module is used to discretize the generator power from zero to the maximum power generation into N power points, and establish the range extender power generation power sequence P APU ; The second sequence building module is used to generate power sequence P through the range extender APU , the range extender's lowest specific fuel consumption sequence under the corresponding power generation and the fuel's lower calorific value, and the lowest fuel consumption power sequence P under the range extender's corresponding power generation is obtained fuel,APU ; The third sequence building module is used to generate the electric power P required by the vehicle in S2. dem and the range extender power sequence P APU , get the battery net power sequence P bat,net , combined with the battery internal resistance and open circuit voltage, the internal resistance power consumption sequence P is obtained bat,res ; Sequence analysis module, used to sequence the battery net power P bat,net and the minimum fuel consumption power sequence P fuel,APU The total power consumption is obtained, and the start / stop command of the range extender is determined according to the total power consumption.

10. A vehicle, characterized in that: A range extender start-stop control method as described in any one of claims 1 to 8 is adopted.

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