Power acceleration control method for series-parallel connection configuration hybrid electric vehicle

Abstract

The invention discloses a power acceleration control method for a series-parallel hybrid electric vehicle, which comprises the following steps of: S1, monitoring the acceleration state of a full accelerator of the vehicle so as to obtain the acceleration state data of the vehicle; s2, the maximum wheel end driving torque in the vehicle series connection mode is calculated; s3, the maximum wheel end torque of the vehicle in the parallel connection mode is calculated; s4, predicting the state of the next speed sampling point of the vehicle; and S5, state prediction is carried out on a plurality of subsequent continuous speed sampling points according to the step S4, whether series-parallel connection switching is carried out or not is comprehensively judged based on data of the sampling points, and whether the vehicle needs to adjust an acceleration strategy or not is judged by collecting various kinds of information under the vehicle running state and predicting state information of the vehicle at a plurality of subsequent collecting points. The power acceleration control method of the series-parallel configuration hybrid electric vehicle has the effect of ensuring that the power assembly system of the vehicle can exert the optimal acceleration capability.

Description

Technical Field

[0001] The present invention relates to the technical field of hybrid vehicles, and in particular to a power acceleration control method for a series-parallel hybrid vehicle. Background Art

[0002] During full throttle acceleration of a hybrid vehicle, the vehicle's hybrid mode (series / parallel) switching conditions are determined based on the software's internal calibration data. The software's internal calibration data is a fixed value and cannot be changed.

[0003] In the vehicle control software, the hybrid mode switching conditions usually need to consider the driver's pedal demand torque, battery SOC (state of charge), vehicle speed and other parameters. Under a certain SOC, when the vehicle speed exceeds the calibrated threshold and the driver's pedal demand torque is in the appropriate range, the vehicle's operating mode is switched from series to parallel to obtain the vehicle's optimal acceleration capability. Alternatively, some car manufacturers will sacrifice vehicle acceleration performance and use a single mode (series) to complete the vehicle's full throttle acceleration condition.

[0004] Existing technical solutions can bring out the optimal performance of the vehicle power system under specific conditions, but this method of using fixed calibration data cannot adapt to all full-throttle acceleration conditions. For example, the motor is torque-limited due to its own fault, or the engine's external characteristic torque is attenuated at high altitudes, or the discharge power is attenuated at the same SOC due to battery aging. The above scenarios will cause the calibration data inside the software to deviate from the optimal solution for the actual state. If the vehicle's power acceleration is not the optimal solution, the vehicle's acceleration performance will decline, resulting in the vehicle's acceleration performance being lower than the driver's expectations, with potential risks to personal safety. Summary of the invention

[0005] In view of the above problems, a power acceleration control method for a series-parallel hybrid vehicle is provided, aiming to solve the problems existing in the prior art.

[0006] The specific technical solutions are as follows:

[0007] A power acceleration control method for a series-parallel hybrid vehicle, the method comprising the following steps:

[0008] S1, vehicle full throttle acceleration state monitoring to obtain vehicle acceleration state data;

[0009] S2, calculating the maximum wheel end driving torque in the vehicle series mode;

[0010] S3, calculating the maximum wheel end torque in the vehicle parallel mode;

[0011] S4, predicting the state of the next speed sampling point of the vehicle;

[0012] S5. According to step S4, a state prediction is performed for a plurality of subsequent continuous speed sampling points, and based on the data of the plurality of sampling points, a comprehensive judgment is made as to whether to perform series-parallel switching.

[0013] The above-mentioned power acceleration control method for a series-parallel hybrid vehicle also has the following characteristics: the vehicle acceleration state data acquired in step S1 includes the vehicle speed V current 、Motor drive speed ratio α motor 、Engine drive speed ratio α engine 、Vehicle acceleration α vehicle 、Battery current charge SOC current , generator power P generator , transmission efficiency from engine to wheels η engine , transmission efficiency from motor to wheel η motor 、Battery current voltage V battrey 、Battery current I battrey 、Current motor speed n motor 、Total battery capacity C battrey 、Battery maximum discharge power P battrey , current vehicle operating mode, current motor torque T motor-current , Current engine torque T engine-current , Motor torque rise rate T ramp-rate-motor , Engine torque increase rate T ramp-rate-engine .

[0014] The above-mentioned power acceleration control method of a series-parallel hybrid vehicle also has the following characteristics: the calculation process in step S2 includes:

[0015] T series-max,wheel =T motor-max *α motor *η motor

[0016] T motor-max =min(T motor-component , T motor-epower , T motor-ramp )

[0017]

[0018] T motor-ramp =T current +T ramp-rate-motor

[0019] Where:

[0020] T series-max，wheel The maximum wheel end driving torque in the vehicle series mode;

[0021] Tmotor-component is the maximum torque of the driving motor body;

[0022] T motor-epower The maximum output torque of the motor that can be satisfied by the system electrical power;

[0023] t motor-ramp To consider the maximum torque that can be achieved by calculating the step size at the next moment after the motor torque rise filter coefficient is limited.

[0024] The above-mentioned power acceleration control method of a series-parallel hybrid vehicle also has the following characteristics: the calculation process of step S3 includes:

[0025] T parallel-max,wheel

[0026] =T motor-max *α motor *η motor +T engine-max *α engine *η engine

[0027] T motor-max =min(T motor-component , T motor-epower , T motor-ramp )

[0028]

[0029] T enginer-max =min(T enginer-component , T enginer-ramp )

[0030] T enginer-ramp =T engine-current +T ramp-rate-engine

[0031] Where:

[0032] T parallel-max，wheel is the maximum wheel end torque in vehicle parallel mode;

[0033] T enginer-component is the maximum torque of the engine body;

[0034] T enginer-ramp The maximum torque that can be achieved by calculating the step size at the next moment after considering the engine torque rising filter coefficient limitation.

[0035] The above-mentioned power acceleration control method of a series-parallel hybrid vehicle also has the following characteristics: the step S4 further includes the following steps:

[0036] S41, calculating the time t required for the vehicle to reach the next speed sampling point;

[0037] S42, calculate the vehicle's next speed sampling point SOC next ;

[0038] S43, VCU sends the predicted SOC value to BMS to obtain the battery discharge power P at the next speed sampling point battrey-next ;

[0039] S44, VCU calculates the engine speed at the next speed sampling point and the drive motor speed;

[0040] S45, VCU calculates the electric power P that the generator can generate at the next speed sampling point of the vehicle generator-next ;

[0041] S46, the VCU calculates the maximum torque of the engine and the maximum torque of the drive motor at the next speed sampling point;

[0042] S47, VCU sends the engine operating point and motor operating point of the next speed sampling point to TCU, and TCU feeds back the engine driving efficiency η at the next speed sampling point engine-next , the driving efficiency η of the driving motor motor-next ;

[0043] S48. Calculate the maximum wheel end torque of the vehicle in different hybrid power modes at the next moment.

[0044] The above-mentioned power acceleration control method of the series-parallel configuration hybrid vehicle also has the following feature: step S5 includes that when the vehicle judges that the wheel end torque of the current hybrid mode is large in the subsequent n speed sampling points, the vehicle does not need to switch the hybrid mode; if among the next n speed sampling points, at a certain speed sampling point the wheel end torque of another hybrid mode is large and can be continuously maintained for n1 (n1 is a value less than n) sampling points, the vehicle needs to switch the mode at the turning speed sampling point to obtain the optimal acceleration performance.

[0045] In summary, the beneficial effects of this scheme are:

[0046] In the power acceleration control method of a series-parallel hybrid vehicle provided by the present invention, by collecting various information under the vehicle's running state and predicting the vehicle's state information at multiple subsequent collection points, it is determined whether the vehicle needs to adjust its acceleration strategy. The power acceleration control method of a series-parallel hybrid vehicle provided by the present invention has the effect of ensuring that the vehicle's powertrain system can exert optimal acceleration capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A system block diagram of a power acceleration control method for a series-parallel hybrid vehicle according to the present invention;

[0048] Figure 2 The present invention discloses a specific flow chart of predicting vehicle status in a power acceleration control method for a series-parallel hybrid vehicle. DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0051] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0052] In the accompanying drawings, Figure 1 is a system block diagram of the power acceleration control method of a series-parallel hybrid vehicle described in the present invention, Figure 2 The specific flow chart of the vehicle state prediction of the power acceleration control method of the series-parallel hybrid vehicle recorded in the present invention is as follows: Figure 1 and Figure 2 As shown, the power acceleration control method of a series-parallel hybrid vehicle provided in this embodiment includes the following steps:

[0053] S1, vehicle full throttle acceleration state monitoring to obtain vehicle acceleration state data;

[0054] S2, calculating the maximum wheel end driving torque in the vehicle series mode;

[0055] S3, calculating the maximum wheel end torque in the vehicle parallel mode;

[0056] S4, predicting the state of the next speed sampling point of the vehicle;

[0057] S5. According to step S4, a state prediction is performed for a plurality of subsequent continuous speed sampling points, and based on the data of the plurality of sampling points, a comprehensive judgment is made as to whether to perform series-parallel switching.

[0058] It should be noted that this solution is applicable to hybrid vehicles with a P1P3 hybrid architecture, which consists of an engine, two motors and a gearbox. A typical case is the single-speed P1P3 solution: the speed ratio from the engine to the vehicle's drive wheels is a single fixed value, and the speed ratio from the motor to the vehicle's drive wheels is a single fixed value.

[0059] In the above embodiment, the vehicle acceleration state data acquired in step S1 includes the vehicle speed Vcurrent 、Motor drive speed ratio α motor 、Engine drive speed ratio α engine 、Vehicle acceleration α vehicle 、Battery current charge SOC current , generator power P generator , transmission efficiency from engine to wheels η engine , transmission efficiency from motor to wheel η motor 、Battery current voltage V battrey 、Battery current I battrey 、Current motor speed n motor 、Total battery capacity C battrey 、Battery maximum discharge power P battrey , current vehicle operating mode, current motor torque T motor-current , Current engine torque T engine-current , Motor torque rise rate T ramp-rate-motor , Engine torque increase rate T ramp-rate-engine .

[0060] It should be noted that when the VCU detects that the driver's accelerator pedal opening is greater than 99%, the full throttle series-parallel mode is activated to switch the vehicle speed real-time calculation module and record the vehicle acceleration status data.

[0061] The above-mentioned power acceleration control method of a series-parallel hybrid vehicle also has the following characteristics: the calculation process in step S2 includes:

[0062] T series-max,wheel =T motor-max *α motor *η motor

[0063] T motor-max =min(T motor-component , T motor-epower , T motor-ramp )

[0064]

[0065] T motor-ramp =T current +T ramp-rate-motor

[0066] Where:

[0067] T series-max，wheel The maximum wheel end driving torque in the vehicle series mode;

[0068] T motor-component is the maximum torque of the driving motor body;

[0069] T motor-epowerThe maximum output torque of the motor that can be satisfied by the system electrical power;

[0070] T motor-ramp To consider the maximum torque that can be achieved by calculating the step size at the next moment after the motor torque rise filter coefficient is limited.

[0071] It should be noted that the VCU calculates the maximum output torque of the motor components at the current vehicle speed, combines the vehicle system power limit and the component torque change rate limit, and obtains the maximum wheel-end driving torque of the vehicle in series mode.

[0072] In the above embodiment, the calculation process of step S3 includes:

[0073] T parallel-max，wheel

[0074] =T motor-max *α motor *η motor +T engine-max *α engine *η engine

[0075] T motor-max =min(T motor-component , T motor-epower , T motor-ramp )

[0076]

[0077] T enginer-max =min(T enginer-component , T enginer-ramp )

[0078] T enginer-ramp =T engine-current +T ramp-rate-engine

[0079] Where:

[0080] T parallel-max，wheel is the maximum wheel end torque in vehicle parallel mode;

[0081] T enginer-component is the maximum torque of the engine body;

[0082] T enginer-ramp The maximum torque that can be achieved by calculating the step size at the next moment after considering the engine torque rising filter coefficient limitation.

[0083] It should be noted that the VCU calculates the wheel-end output torque of the engine and P3 motor in parallel in the current mode, combined with the vehicle power limit, to obtain the maximum wheel-end driving torque of the vehicle in parallel mode.

[0084] In the above embodiment, step S4 further includes the following steps:

[0085] S41, calculating the time t required for the vehicle to reach the next speed sampling point;

[0086] S42, calculate the vehicle's next speed sampling point SOC next ;

[0087] S43, VCU sends the predicted SOC value to BMS to obtain the battery discharge power P at the next speed sampling point battrey-next ;

[0088] S44, VCU calculates the engine speed at the next speed sampling point and the drive motor speed;

[0089] S45, VCU calculates the electric power P that the generator can generate at the next speed sampling point of the vehicle generator-next ;

[0090] It should be noted that P generator-next The calculation formula is:

[0091] P generator-next =min(P generator-ramp , P generator-next , P engine-next )

[0092] Where:

[0093] P generator-next The maximum electric power of the generator at the next moment after considering the filter coefficient;

[0094] P generator-next The maximum power limit of the generator hardware at the next speed sampling point;

[0095] P engine-next It is the maximum power limit of the engine hardware at the next speed sampling point.

[0096] S46, the VCU calculates the maximum torque of the engine and the maximum torque of the drive motor at the next speed sampling point;

[0097] It should be noted that the calculation of the maximum torque of the engine and the maximum torque of the drive motor is the same as the algorithm in step S3 and step S4.

[0098] S47, VCU sends the engine operating point and motor operating point of the next speed sampling point to TCU, and TCU feeds back the engine driving efficiency η at the next speed sampling point engine-next , driving efficiency η of the driving motor motor-next ;

[0099] S48. Calculate the maximum wheel end torque of the vehicle in different hybrid power modes at the next moment.

[0100] It should be noted that the detailed calculation method in steps S41 to S48 refers to the calculation method in steps S2 and S3, and will not be repeated here.

[0101] In the above embodiment, step S5 includes that when the vehicle determines that the wheel-end torque of the current hybrid mode is large in the subsequent n speed sampling points, the vehicle does not need to switch the hybrid mode; if, among the next n speed sampling points, at a certain speed sampling point the wheel-end torque of another hybrid mode is large and can be continuously maintained for n1 (n1 is a value less than n) sampling points, the vehicle needs to switch the mode at the turning speed sampling point to obtain the optimal acceleration performance.

[0102] Working principle, through analyzing a specific vehicle, taking the influence of battery aging as an example for analysis, when the battery is at 50% SOC, when the battery is normal, the vehicle should adopt series mode before the speed of 83km / h, and parallel mode after 83km / h to obtain the maximum acceleration of the wheel end, but when the battery is aged, the battery discharge power decays, and the original relationship does not hold true. The vehicle should switch to hybrid mode at a speed of 71km / h. This solution can realize the real-time online calculation of the hybrid power mode (series / parallel) switching conditions under the condition of full throttle acceleration of the vehicle, ensuring that the vehicle's powertrain system can exert the optimal acceleration capability.

[0103] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A power acceleration control method for a series-parallel hybrid vehicle, characterized in that: The method comprises the following steps: S1, vehicle full throttle acceleration state monitoring to obtain vehicle acceleration state data; S2, calculating the maximum wheel end driving torque in the vehicle series mode; S3, calculating the maximum wheel end torque in the vehicle parallel mode; S4, vehicle state prediction for the next speed sampling point; S5. According to step S4, a state prediction is performed for a plurality of subsequent continuous speed sampling points, and based on the data of the plurality of sampling points, a comprehensive judgment is made as to whether to perform series-parallel switching.

2. The power acceleration control method of a series-parallel hybrid vehicle according to claim 1, characterized in that: The vehicle acceleration state data acquired in step S1 includes the vehicle speed V current 、Motor drive speed ratio α motor 、Engine drive speed ratio α engine 、Vehicle acceleration α vehicle 、Battery current charge SOC current , generator power P generator , transmission efficiency from engine to wheels η engine , transmission efficiency from motor to wheel η motor 、Battery current voltage V battrey 、Battery current I battrey 、Current motor speed n motor 、Total battery capacity C battrey 、Battery maximum discharge power P battrey , current vehicle operating mode, current motor torque T motor-current , Current engine torque T engine-current , Motor torque rise rate T ramp-rate-motor , Engine torque increase rate T ramp-rate-en gine .

3. The power acceleration control method of a series-parallel hybrid vehicle according to claim 2, characterized in that: The calculation process in step S2 includes: T series-max,wheel =T motor-max *a motor *or motor T motor-max =min(T motor-component ,T motor-epower ,T motor-ramp ) T motor-ramp =T current +T ramp-rate-motor Where: T series-max,wheel The maximum wheel end driving torque in the vehicle series mode; T motor-component is the maximum torque of the driving motor body; T motor-epower The maximum output torque of the motor that can be satisfied by the system electrical power; T motor-ramp To consider the maximum torque that can be achieved by calculating the step size at the next moment after the motor torque rise filter coefficient is limited.

4. The power acceleration control method of a series-parallel hybrid vehicle according to claim 3, characterized in that: The calculation process of step S3 includes: T parallel-max,wheel =T motor-max *a motor *or motor +T engine-max *a engine *or engine T motor-max =min(T motor-component ,T motor-epower ,T motor-ramp ) T enginer-max =min(T enginer-component ,T enginer-ramp ) T enginer-ramp =T engine-current +T ramp-rate-engine Where: T parallel-max,wheel is the maximum wheel end torque in vehicle parallel mode; T enginer-component is the maximum torque of the engine body; T enginer-ramp The maximum torque that can be achieved by calculating the step size at the next moment after considering the engine torque rising filter coefficient limitation.

5. The power acceleration control method of a series-parallel hybrid vehicle according to claim 4, characterized in that: The step S4 also includes the following steps: S41, calculating the time t required for the vehicle to reach the next speed sampling point; S42, calculate the vehicle's next speed sampling point SOC next ; S43, VCU sends the predicted SOC value to BMS to obtain the battery discharge power P at the next speed sampling point battrey-next ; S44, VCU calculates the engine speed at the next speed sampling point and the drive motor speed; S45, VCU calculates the electric power P that the generator can generate at the next speed sampling point of the vehicle generator-next ; S46, the VCU calculates the maximum torque of the engine and the maximum torque of the drive motor at the next speed sampling point; S47, VCU sends the engine operating point and motor operating point of the next speed sampling point to TCU, and TCU feeds back the engine driving efficiency η at the next speed sampling point engine-next , the driving efficiency η of the driving motor motor-next ; S48. Calculate the maximum wheel end torque of the vehicle in different hybrid power modes at the next moment.

6. The power acceleration control method of a series-parallel hybrid vehicle according to claim 5, characterized in that: The step S5 includes that when the vehicle determines that the wheel-end torque of the current hybrid mode is large in the subsequent n speed sampling points, the vehicle does not need to switch the hybrid mode; if, among the next n speed sampling points, at a certain speed sampling point the wheel-end torque of another hybrid mode is large and can be continuously maintained for n1 (n1 is a value less than n) sampling points, the vehicle needs to switch the mode at the turning speed sampling point to obtain the optimal acceleration performance.

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