Energy management method and plug-in hybrid electric vehicle

Abstract

The present invention relates to the field of hybrid electric vehicles, and in particular to an energy management method and a plug-in hybrid electric vehicle. The energy management method includes: judging whether the temperature of the engine exhaust after-treatment device meets the requirements for normal operation; when the requirements for normal operation are met, the engine SOC start-up condition is that the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than a first threshold; when the requirements for normal operation are not met, the engine SOC start-up condition is that the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than a second threshold; wherein, the second threshold is greater than the first threshold, prompting the engine to start in advance to heat the engine exhaust after-treatment device and reduce pollutant emissions. The above energy management method adjusts the engine start-up SOC by judging whether the temperature of the engine exhaust after-treatment device meets the requirements for normal operation, effectively reducing vehicle emissions and achieving the purpose of emission reduction.

Description

Technical Field

[0001] The present invention relates to the field of hybrid electric vehicles, and in particular to an energy management method and a plug-in hybrid electric vehicle. Background Art

[0002] With the continuous advancement of energy conservation and emission reduction, the popularization of new energy vehicles has become inevitable. Among new energy vehicles, plug-in hybrid electric vehicles (PHEVs) have attracted widespread attention from both industry and academia due to their ability to effectively reduce fuel consumption and carbon dioxide emissions, while eliminating range anxiety. Existing research has shown that the implementation of an optimized energy management strategy (EMS) can fully tap the energy conservation and emission reduction potential of PHEVs.

[0003] Most existing EMSs use a conventional charge depletion-charge sustaining (CD-CS) mode for PHEV control. This involves initially using pure electric power, then fully reverting to the internal combustion engine when the battery's state of charge (SOC) drops to a fixed value. This two-stage, pure electric-fuel-only control approach results in engine emissions similar to those of pure internal combustion engine vehicles, impacting the PHEV's emissions reduction effectiveness. Summary of the Invention

[0004] Based on this, it is necessary to provide an energy management method for plug-in hybrid vehicles to address the above technical problems, adjust the engine startup SOC according to the temperature of the engine emission after-treatment device, effectively reduce the vehicle emissions, and achieve the purpose of emission reduction.

[0005] An energy management method is applied to a plug-in hybrid electric vehicle, wherein the vehicle includes a battery, an engine, an engine exhaust after-treatment device, and a motor. The energy management method includes:

[0006] Determining whether the temperature of the engine exhaust after-treatment device meets the requirements for normal operation;

[0007] When the temperature of the engine exhaust after-treatment device meets the normal operation requirement, the SOC start condition of the engine is that the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than a first threshold;

[0008] When the temperature of the engine exhaust after-treatment device does not meet the normal operation requirement, the engine SOC start condition is that the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than a second threshold;

[0009] The second threshold is greater than the first threshold, which prompts the engine to start early to heat the engine exhaust after-treatment device and reduce pollutant emissions.

[0010] In one embodiment, the energy management method further includes:

[0011] Obtaining a real-time SOC value of the battery;

[0012] A real-time reference SOC value of the battery is calculated.

[0013] In one embodiment, the step of calculating the real-time reference SOC value of the battery includes:

[0014] Get the driver's mileage information;

[0015] Obtaining a starting SOC value of the battery when the vehicle is started;

[0016] Providing the minimum allowable SOC value of the battery;

[0017] Calculating an allowable SOC drop per kilometer of the battery based on the mileage information, the starting SOC value of the battery, and the allowable minimum SOC value of the battery;

[0018] The real-time reference SOC value of the battery is calculated based on the real-time SOC value of the battery and the allowable SOC drop per kilometer of the battery.

[0019] In one embodiment, the mileage information of the driver is obtained from a commercial map.

[0020] In one embodiment, the mileage information of the driver is obtained from the driver's side.

[0021] In one embodiment, the energy management method further includes:

[0022] Estimating the energy consumption of the vehicle at a certain time in the future;

[0023] Determining whether the engine meets energy consumption start-up conditions based on the energy consumption of the vehicle in a certain future time domain;

[0024] When the engine meets the energy consumption starting condition, the vehicle enters the hybrid mode;

[0025] When the engine does not meet the energy consumption starting conditions, the vehicle maintains the pure electric mode.

[0026] In one embodiment, a vehicle speed prediction algorithm is used in combination with the longitudinal dynamics equation of the entire vehicle to estimate the energy consumption of the vehicle in a certain time domain in the future.

[0027] In one embodiment, the energy management method further includes:

[0028] determining whether the temperature of the engine exhaust after-treatment device meets normal operating requirements when the vehicle enters the hybrid mode;

[0029] When the temperature of the engine exhaust after-treatment device meets the normal working requirements, setting the emission penalty factor in the cost function of controlling the operation of the engine and the motor to 0;

[0030] When the temperature of the engine exhaust after-treatment device does not meet the normal working requirements, determining the speed pattern of the vehicle within a certain time range in the future;

[0031] The emission penalty factor in the cost function is set accordingly according to the speed pattern of the vehicle within a certain time domain in the future.

[0032] In one embodiment, the energy management method further includes:

[0033] determining whether a difference between the real-time SOC value of the battery and a real-time SOC reference value is greater than a third threshold;

[0034] When the difference between the real-time SOC value of the battery and the real-time SOC reference value is greater than a third threshold, the engine is shut down and the vehicle enters a pure electric mode;

[0035] When the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than or equal to a third threshold, the vehicle maintains the hybrid mode.

[0036] A plug-in hybrid electric vehicle uses the energy management method described in any one of the above embodiments.

[0037] The energy management method and plug-in hybrid electric vehicle adjust the engine startup SOC by determining whether the temperature of the engine exhaust after-treatment device meets the normal operation requirements, thereby effectively reducing vehicle emissions and achieving the goal of emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a flow chart of an energy management method in one embodiment;

[0039] Figure 2 is a flow chart of an energy management method in another embodiment;

[0040] Figure 3 The figure is a flow chart of the steps of calculating the real-time reference SOC value of the battery in one embodiment. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] Figure 1 FIG. 1 is a flow chart of an energy management method in one embodiment. Figure 1 As shown, an energy management method is applied to a plug-in hybrid electric vehicle, wherein the vehicle includes a battery, an engine, an engine exhaust after-treatment device, and a motor. The energy management method includes:

[0043] S110, determining whether the temperature of the engine exhaust after-treatment device meets the requirements for normal operation.

[0044] Specifically, in traditional engine aftertreatment devices, when high-temperature engine exhaust passes through the device, the three gases in the exhaust pollutants—carbon monoxide, non-methane hydrocarbons, and nitrogen oxides—react chemically. At high temperatures, carbon monoxide oxidizes to form colorless, non-toxic carbon dioxide; non-methane hydrocarbons oxidize to form water and carbon dioxide; and nitrogen oxides are reduced to nitrogen and oxygen. These three harmful gases are transformed into harmless gases, purifying the vehicle's exhaust. The typical ignition temperature for exhaust aftertreatment devices is 400-800 degrees Celsius. Within this temperature range, the catalyst's conversion efficiency for exhaust pollutants is greater than 95%, effectively reducing engine exhaust pollutants and converting them into water, nitrogen, and oxygen. If the catalyst temperature falls below this, the conversion efficiency suddenly decreases, approaching zero below 200 degrees Celsius, effectively rendering the exhaust pollutants inoperable.

[0045] Furthermore, in practical applications, the normal operating reference temperature of the engine exhaust after-treatment device may be selected based on the adopted after-treatment device.

[0046] S120, when the temperature of the engine exhaust after-treatment device meets the normal working requirements, the SOC starting condition of the engine is the real-time SOC value SOC of the battery act and real-time SOC reference value SOC ref The difference is less than the first threshold.

[0047] Specifically, when the temperature of the engine exhaust after-treatment device meets the normal working requirements and the real-time SOC value SOC act Reduce to meet SOC act -SOC ref When the temperature drops below the first threshold, the engine is started and the vehicle switches from a pure electric mode to a hybrid mode.

[0048] S130, when the temperature of the engine exhaust after-treatment device does not meet the normal operating requirement, the engine SOC starting condition is that the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than a second threshold;

[0049] Specifically, when the temperature of the engine exhaust after-treatment device does not meet the normal working requirements, and the real-time SOC value SOC act Reduce to meet SOC act -SOC ref When the temperature drops below the second threshold, the engine is started and the vehicle switches from a pure electric mode to a hybrid mode.

[0050] Furthermore, the second threshold is greater than the first threshold. When the temperature of the engine exhaust after-treatment device does not meet the requirements for normal operation, the engine is prompted to start in advance when the SOC is higher to heat the engine exhaust after-treatment device, improve the emission quality of the engine, and reduce pollutant emissions; the first threshold and the second threshold can be determined by the model of the car and the common operating conditions, and the second threshold can also be adjusted accordingly according to the deviation value between the temperature of the engine exhaust after-treatment device and the temperature required for normal operation.

[0051] Figure 2 FIG. 1 is a flow chart of an energy management method in another embodiment. Figure 2 As shown, the energy management method may further include:

[0052] S140, obtaining a real-time SOC value of the battery;

[0053] S150: Calculate a real-time reference SOC value of the battery.

[0054] Figure 3 FIG. 1 is a flow chart of the steps for calculating the real-time reference SOC value of the battery in one embodiment, as shown in FIG. Figure 3 As shown, the step S150 of calculating the real-time reference SOC value of the battery may include:

[0055] S151, obtaining the mileage information S of the driver's current driving.

[0056] S152, obtaining the starting SOC value SOC of the battery when the vehicle is started pri .

[0057] S153, providing the battery's minimum allowable SOC value SOC min .

[0058] S154, based on the mileage information S and the starting SOC value SOC of the battery pri And the allowable minimum SOC value SOC of the batterymin , calculate the allowable SOC drop value ΔSOC per kilometer of the battery;

[0059] Specifically, the ΔSOC satisfies

[0060] S155 , calculating a real-time reference SOC value of the battery according to the real-time SOC value of the battery and the allowable SOC drop per kilometer of the battery.

[0061] In one embodiment, the mileage information of the driver can be obtained from a commercial map.

[0062] In one embodiment, the mileage information of the driver's current travel can be obtained from the driver's side; specifically, the driver can manually input the mileage information of the current travel; further, the mileage information of the current travel can be input by rotating an existing mileage knob.

[0063] In one embodiment, the energy management method may further include:

[0064] S160, estimating the energy consumption of the vehicle in a certain time domain in the future;

[0065] S170, determining whether the engine meets energy consumption start-up conditions based on the energy consumption of the vehicle in a certain future time domain;

[0066] S180, when the engine meets the energy consumption starting condition, the vehicle enters the hybrid mode;

[0067] S190: When the engine does not meet the energy consumption starting conditions, the vehicle maintains the pure electric mode.

[0068] In one embodiment, a vehicle speed prediction algorithm may be used in combination with the longitudinal dynamics equation of the entire vehicle to estimate the energy consumption of the vehicle in a certain time domain in the future.

[0069] Specifically, the longitudinal dynamic equation of the vehicle is as follows:

[0070]

[0071] Where, F Traction is the driving force of the vehicle, m is the mass of the vehicle, g is the acceleration of gravity, α is the slope, δ is the rotational mass coefficient, C D C D is the drag coefficient, A is the frontal area, v a For vehicle speed.

[0072] The instantaneous driving force of the vehicle is calculated using the vehicle longitudinal dynamics equation, and then the energy consumption within a certain time domain can be obtained by integrating it over the entire time domain.

[0073] In one embodiment, the energy management method may further include:

[0074] S200 , determining whether the temperature of the engine exhaust after-treatment device meets the normal operating requirements when the vehicle enters the hybrid mode.

[0075] S210, when the temperature of the engine exhaust after-treatment device meets the normal operating requirements, setting the emission penalty factor in the cost function for controlling the operation of the engine and the motor to 0;

[0076] Specifically, when the temperature of the engine exhaust after-treatment device meets the normal operation requirement, emission factors may not be considered when controlling the torque distribution between the engine and the motor, and the emission penalty factor in the cost function is zero.

[0077] The calculation formula of the cost function is as follows:

[0078]

[0079] Where CF is the calculated value of the cost function, t0 is the calculation start time, t f To calculate the end time, is the instantaneous fuel consumption of the engine, λ * is the electric-to-oil equivalent factor corresponding to different vehicle speed modes, P b (t) is the battery power, ω(p) is the emissions penalty factor, and Emissions (NOx + CO + HC) is the sum of the emissions at the engine operating point. As can be seen from the above formula, when the operating temperature of the exhaust aftertreatment device is normal, the cost function no longer considers engine emissions due to the high emission conversion efficiency. Conversely, when the emission conversion efficiency is low, in order to minimize vehicle emissions, it is necessary to calibrate the penalty factor at different speed modes. This value must be greater than 0 to ensure that some emission pollution is suppressed during engine operation.

[0080] S220: When the temperature of the engine exhaust after-treatment device does not meet the normal working requirements, determine the speed pattern of the vehicle within a certain time range in the future.

[0081] S230, setting an emission penalty factor in the cost function according to a speed pattern of the vehicle within a certain time domain in the future;

[0082] Specifically, when the temperature of the engine exhaust after-treatment device does not meet normal operating requirements, emission factors need to be taken into account when controlling the torque distribution between the engine and the motor, and an emission penalty factor in the cost function is set accordingly based on the speed pattern of the vehicle within a certain time domain in the future;

[0083] Furthermore, the speed mode of the car may include a low-speed mode, a medium-speed mode, a high-speed mode, and an ultra-high-speed mode. Accordingly, the corresponding emission penalty factors may include a low-speed emission penalty factor, a medium-speed emission penalty factor, a high-speed emission penalty factor, and an ultra-high-speed emission penalty factor.

[0084] In one of the embodiments, the energy management method may further include.

[0085] S240, determining whether a difference between the real-time SOC value of the battery and the real-time SOC reference value is greater than a third threshold;

[0086] S250, when the difference between the real-time SOC value of the battery and the real-time SOC reference value is greater than a third threshold, the engine is shut down, the battery stops charging, and the vehicle enters a pure electric mode;

[0087] S260 , when the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than or equal to a third threshold, the vehicle maintains the hybrid mode.

[0088] Specifically, the third threshold is greater than the first threshold and the second threshold. When it is determined whether the difference between the real-time SOC value of the battery and the real-time SOC reference value is greater than the third threshold, it can be determined that the battery has sufficient power, and the car can stop charging and operate in pure electric mode.

[0089] A plug-in hybrid electric vehicle uses the energy management method described in any one of the above embodiments.

[0090] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An energy management method, characterized in that: Applied to a plug-in hybrid electric vehicle, the vehicle includes a battery, an engine, an engine exhaust after-treatment device, and a motor. The energy management method includes: Determining whether the temperature of the engine exhaust after-treatment device meets the requirements for normal operation; When the temperature of the engine exhaust after-treatment device meets the normal operation requirement, the SOC start condition of the engine is that the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than a first threshold; When the temperature of the engine exhaust after-treatment device does not meet the normal operation requirement, the engine SOC start condition is that the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than a second threshold; Wherein, the second threshold is greater than the first threshold, prompting the engine to start in advance to heat the engine exhaust after-treatment device and reduce pollutant emissions; Also included: obtaining a real-time SOC value of the battery; Calculating a real-time reference SOC value of the battery; The step of calculating the real-time reference SOC value of the battery includes: Get the driver's mileage information; Obtaining a starting SOC value of the battery when the vehicle is started; Providing the minimum allowable SOC value of the battery; Calculating an allowable SOC drop per kilometer of the battery and an allowable SOC drop per kilometer of the battery ΔSOC according to the mileage information, the starting SOC value of the battery, and the allowable minimum SOC value of the battery; Specifically, the ΔSOC satisfies ; Calculating a real-time reference SOC value of the battery according to the real-time SOC value of the battery and the allowable SOC drop value per kilometer of the battery; The method further includes determining whether a difference between the real-time SOC value of the battery and the real-time SOC reference value is greater than a third threshold; When the difference between the real-time SOC value of the battery and the real-time SOC reference value is greater than a third threshold, the engine is shut down and the vehicle enters a pure electric mode; The vehicle speed prediction algorithm can be used in combination with the longitudinal dynamics equation of the vehicle to estimate the energy consumption of the vehicle in a certain time domain in the future; Specifically, the longitudinal dynamic equation of the vehicle is as follows: ； Where, For the driving force of the vehicle, is the vehicle mass, is the acceleration due to gravity, is the slope, Rotational mass coefficient, is the drag coefficient, is the windward area, is the vehicle speed; Apply the vehicle longitudinal dynamics equation to calculate the instantaneous driving force of the vehicle, and then integrate it over the entire time domain to obtain the energy consumption within a certain time domain; When the difference between the real-time SOC value of the battery and the real-time SOC reference value is less than or equal to a third threshold, the vehicle maintains the hybrid mode; When the temperature of the engine exhaust after-treatment device meets the normal working requirements, setting the emission penalty factor in the cost function of controlling the operation of the engine and the motor to 0; Specifically, when the temperature of the engine exhaust after-treatment device meets the normal operation requirement, emission factors may not be considered when controlling the torque distribution between the engine and the motor, and the emission penalty factor in the cost function is 0; The calculation formula of the cost function is as follows: ； Where, Calculate the value for the cost function, To calculate the start time, To calculate the end time, is the instantaneous fuel consumption of the engine, is the electric-to-oil equivalent factor corresponding to different vehicle speed modes, is the battery power, is the emission penalty factor, are the emissions and values ​​for the engine operating point.

2. The energy management method according to claim 1, characterized in that: The mileage information of the driver's current travel is obtained from a commercial map.

3. The energy management method according to claim 2, characterized in that: The mileage information of the driver's current trip is obtained from the driver's end.

4. The energy management method according to claim 1, characterized in that: Also includes: Estimating the energy consumption of the vehicle at a certain time in the future; Determining whether the engine meets energy consumption start-up conditions based on the energy consumption of the vehicle in a certain future time domain; When the engine meets the energy consumption starting condition, the vehicle enters the hybrid mode; When the engine does not meet the energy consumption starting conditions, the vehicle maintains the pure electric mode.

5. The energy management method according to claim 4, characterized in that: The vehicle speed prediction algorithm is used in combination with the longitudinal dynamics equation of the entire vehicle to estimate the energy consumption of the vehicle in a certain time domain in the future.

6. The energy management method according to claim 1, characterized in that: Also includes: determining whether the temperature of the engine exhaust after-treatment device meets normal operating requirements when the vehicle enters the hybrid mode; When the temperature of the engine exhaust after-treatment device does not meet the normal working requirements, determining the speed pattern of the vehicle within a certain time range in the future; The emission penalty factor in the cost function is set accordingly according to the speed pattern of the vehicle within a certain time domain in the future.

7. A plug-in hybrid electric vehicle, characterized in that: Use the energy management method according to any one of claims 1 to 6.

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