CN107117159B - A kind of CVT parallel hybrid electrics operator demand's torque estimation method - Google Patents

Abstract

The invention discloses a method for estimating the driver's demand torque of a CVT parallel hybrid electric vehicle. The method aims at the difference between whether the two power sources work or not under different modes of the parallel hybrid electric vehicle, and solves the composite external characteristics of the power system based on the mode to obtain the real maximum value of the system. Output characteristics; Aiming at the characteristics that the CVT speed ratio stepless change characteristics affect the output, the CVT input speed range can be obtained from the vehicle speed and speed ratio range i _g ; then the input speed limit is obtained based on the optimal speed range of the main power source in different modes; by After limiting, the input speed is interpolated and combined with the external characteristics to obtain the input torque range; then the output torque range and the maximum output torque value of the system are obtained from the speed ratio; finally, the exact value of the required torque is obtained from the accelerator pedal. This method solves the complex external characteristics of the power system and the optimal operating speed range based on the model, and obtains the torque range and the real maximum output characteristics of the system through the CVT speed ratio stepless change characteristics, so that the required torque can be accurately estimated and improved. Power performance and driving experience.

Description

A method for estimating driver demand torque of CVT parallel hybrid electric vehicle

technical field

The invention belongs to the technical field of parallel hybrid electric vehicles, in particular to a method for estimating driver demand torque of a CVT parallel hybrid electric vehicle.

Background technique

As energy and environmental issues become increasingly severe, energy-saving and new energy vehicle technologies have become the focus of the government and enterprises. Hybrid vehicles have become one of the popular directions of new energy vehicles due to their good fuel economy and low emissions. Among them, the parallel hybrid vehicle has been widely developed and applied due to its relatively simple structure and easy control. And with the improvement of the design and manufacturing level and control technology of CVT mechanical continuously variable transmission, its application in hybrid electric vehicles is also increasing.

In the prior art, there are few patents on driver demand torque estimation of CVT parallel hybrid electric vehicles, and other related patents on demand torque estimation are not aimed at the characteristics that the CVT speed ratio can be changed quickly and steplessly in a wide range, nor are there any Aiming at the characteristics of parallel hybrid electric vehicles that different optimal operating speed ranges of the main power sources in different driving modes have different restrictions on the speed range of the input end of the CVT, and that whether the two power sources work or not under different driving modes has a great influence on the maximum output capacity of the power system, This is not good for the power performance and driving experience of the car. For example, the Chinese patent publication number is CN102897214A, and the publication date is 2013-01-30, which discloses a method for analyzing driver demand torque. In a hybrid electric vehicle, the motor and engine external characteristic torque curves are summed as a composite torque array of the power system; another example is the Chinese patent publication number CN104648404A, the publication date is 2015-05-27, which discloses a driver driving Intent analysis method, the method uses the sum of the maximum torque of the engine at the output shaft end and the maximum driving torque of the motor at the output shaft end as the required torque when the accelerator pedal is 100% open; For 2014-09-10, a hybrid electric vehicle and its power system torque control method are disclosed. The maximum driving torque is the maximum torque capacity of the power system, that is, the maximum torque of the power system is the sum of the maximum torque of the engine and the motor; although the state of the battery, motor, engine and other components in the current power system is considered, it does not Considering the important state of whether the engine and the motor are involved in the current mode, the maximum drive torque that can be realized in all operating modes is taken as the maximum torque capacity of the power system, and the maximum torque of the motor and the engine is actually summed . Therefore, the above three methods are not completely reasonable, because in some modes, only one of the motor and the engine works, and the maximum output characteristics of the system will change greatly with different driving modes, so the maximum torque of the two power sources is simply added directly and combined. It cannot accurately represent the real-time real maximum output characteristics of the vehicle power system.

At the same time, in the method described in the above-mentioned Chinese Patent Publication No. CN102897214A, the motor speed in the full range from 0 to the maximum speed is used to solve the maximum output torque at each gear and input speed according to the composite torque of the power system. This method cannot solve the problem that the optimal operating speed range of the main power source of the hybrid vehicle in different driving modes will have different restrictions on the speed range of the input end of the CVT. Its fuel consumption is poor in low-speed and high-speed areas, and the control strategy generally does not allow the engine to work in this area.

In view of the above-mentioned technical deficiencies, a method for estimating the driver's demand torque of a CVT parallel hybrid electric vehicle according to the present invention adopts a mode-based The real maximum output characteristics of the power system can be obtained by solving the compound external characteristics of the power system; and in view of the fact that the CVT speed ratio can be rapidly and steplessly changed in a wide range and has a direct impact on the output characteristics, the CVT input is calculated from the vehicle speed and speed ratio range i _g available speed range array S _ava at the end; then solve the optimal operating speed range S _lim of the main power source based on the current mode, and limit the available speed at the input end to obtain the optimal speed range S _opt available at the current vehicle speed; then interpolate from each speed The input end torque range T _in is obtained by compounding external characteristics; the output end torque range T _out is obtained by the speed ratio corresponding to each speed; and the maximum torque value of the system is obtained for each speed ratio; finally, the maximum output torque of the system is obtained by The accelerator pedal gets the exact value of the real-time demand torque. This method solves the composite external characteristics of the power system based on the drive mode, and according to the characteristics of the CVT speed ratio that can be changed steplessly and the optimal speed difference in different modes, the torque range is obtained through the speed range, and finally the maximum value is obtained to obtain the real maximum output characteristics of the system. It can accurately estimate the driver's real-time demand torque, thereby improving the vehicle's power performance and driving experience.

Contents of the invention

In order to solve the deficiencies in the prior art, the present invention provides a method for estimating the driver's demand torque of a CVT parallel hybrid electric vehicle, which takes into account the difference between whether the two power sources work or not under different drive modes, and adopts a mode-based power The real maximum output characteristics of the power system can be obtained by solving the compound external characteristics of the system; and considering that the CVT speed ratio can be rapidly and steplessly changed in a wide range and has a direct impact on the output characteristics, it can be used to solve the CVT input through the vehicle speed and speed ratio range. Speed range array S _ava ; at the same time, the difference in the optimal operating speed range S _opt of the main power source in different modes is also considered to obtain the optimal speed range S _opt of the input end in the current mode; and then the corresponding external characteristics are obtained through interpolation and speed ratio Input and output torque, so that the current real maximum output torque of the system can be obtained by maximizing the torque value under each speed ratio, and finally the required torque is obtained by the pedal. Therefore, this method fully considers the structural characteristics of the CVT parallel hybrid electric vehicle and the influence of the different power sources participating in the work of each driving mode on the maximum output capacity of the system and the limitation of the input speed range on the optimal operating speed range. At the same time, the CVT The characteristics of stepless change in speed ratio, so that the real maximum output characteristics of the system can be accurately obtained, and then the precise result of the driver's demand torque can be obtained.

In order to achieve the above object, a method for estimating the driver's demand torque of a CVT parallel hybrid electric vehicle according to an embodiment of the present invention includes the following steps:

Step 1. According to the characteristic that the electric motor and engine of the parallel hybrid electric vehicle are located at the CVT input end, whether each power source participates in the drive will be different under different driving modes; firstly, according to the external characteristics of the two power sources, the power The method of solving the complex external characteristics of the system can obtain the maximum input torque of the power system at each input speed;

Step 2, aiming at the characteristics that the CVT speed ratio can be changed rapidly and steplessly in real time, as shown in formula (1), the actual vehicle speed v is based on the CVT speed ratio range array i _g (the speed ratio range array interval is not less than the CVT speed ratio change A small value of the sensitivity, such as 0.1) Solve the available speed range S _ava of the input end of the CVT at the current vehicle speed, and then obtain the various speeds S _ava corresponding to the real-time vehicle speed and any speed ratio i _{s_ava} ; that is, according to the current vehicle speed The value v can be two arrays of speed ratio and speed, and the speed ratio value and the speed value correspond to each other;

In the formula, n is the rotation speed of CVT input end, the unit is rpm; i ₀ is the speed ratio of the main reducer; r is the radius of the wheel, the unit is m;

Step 3, according to the different characteristics of the optimal operating speed limit range with higher efficiency of the main power source in different driving modes, based on the optimal operating speed range of the main power source in the current driving mode, the speed limit range S _lim of the CVT input end is obtained; then by The available rotational speed range S _ava of the CVT input terminal at the current vehicle speed, find the intersection of the two, and obtain the currently available optimal operating rotational speed range S _opt of the CVT input terminal, and the corresponding speed ratio of each rotational speed is denoted as _{is_opt} ;

Step 4: Interpolate the composite external characteristic TS curve of the power system under the current driving mode from each rotational speed within the optimal operating rotational speed range S _opt of the CVT input end to obtain the CVT input torque range T _in ; then combine with the values corresponding to each rotational speed S _opt The speed ratio i _{s_opt} is obtained to obtain the output torque range T _out of the CVT;

Step 5, calculate MAX for each torque value within the CVT output torque range T _out under the real-time vehicle speed and mode, and obtain the real maximum output torque T _max of the power system under the current vehicle state (vehicle speed, driving mode) ;

Step 6, obtain the driver's pre-demand torque T′ _req from the maximum output torque T _max of the power system and the accelerator pedal signal k under the current vehicle state;

Step 7, in order to avoid large and rapid fluctuations in the obtained driver's demand torque, limit the change rate of the pre-required torque value T′ _req to obtain the driver's real-time demand torque T _req to prevent rapid fluctuations in the demand torque Changes lead to frequent mode switches or excessive car jerks.

Thus, according to a method for estimating driver demand torque of a CVT parallel hybrid electric vehicle according to the present invention, the real maximum output characteristics of the power system are obtained through the mode-based solution method for the complex external characteristics of the power system, and the CVT under each speed ratio The input terminal can calculate the rotational speed, limit the optimal rotational speed range of the main power source in different modes, obtain the maximum output torque characteristics of the system that can be realized by the CVT, and finally obtain the accurate demand torque. Therefore, the method of the present invention is specially aimed at the working characteristics of parallel hybrid and CVT, and can be detailed, comprehensive, accurate and effective.

In addition, according to the above-mentioned embodiments of the present invention, it may also have the following additional technical features:

According to an embodiment of the present invention, the method for solving the T-S curve of the composite external characteristics of the power system based on the driving mode in the step 1 is to determine the components of the composite external characteristics of the power system according to the participation of the power source in the current driving mode ; That is, the composite external characteristics of the power system only include the maximum output characteristics of the power source that participates in driving and outputs driving force to the driving wheels in the current mode.

According to one embodiment of the present invention, the CVT speed ratio range array i _g in the step 2 refers to the variation range of all transmission ratios that the CVT can realize, and is a fixed parameter determined by the CVT mechanical structure; The CVT input speed limit range S _lim in step 3 above refers to the optimal operating speed range of the main power source defined in the vehicle control strategy in the current driving mode; for example, in the pure electric mode, S _lim is the motor expected by the control strategy The optimal operating speed range (or below the rated speed), S _lim is the optimal operating speed range of the engine expected by the control strategy in other driving modes with engine participation; and the optimal operating speed range of the motor and engine is based on their efficiency/fuel consumption MAP Data calibration to improve the economy of the power system; at the same time, according to the real-time vehicle status and each speed ratio value i _g in the steps 2 to 4, the available speed range S _ava , the optimal operating speed range S _opt of the input end, and the input torque range are obtained T _in and output torque range T _out are all in the form of an array, and each speed/torque value is in one-to-one correspondence with each speed ratio _{is_ava} and _{is_opt} , so that the output characteristics of the CVT can be obtained according to the input characteristics of the CVT, and finally Get the exact needs of the driver.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is the flow chart of a kind of CVT parallel hybrid vehicle driver demand torque estimation method according to the embodiment of the present invention;

Fig. 2 is a flow chart of a method for solving complex external characteristics of a power system based on a model according to an embodiment of the present invention;

3 is a flowchart of a method for solving the torque output capability of the power system considering the characteristics of the stepless change of the CVT speed ratio and the limitation of the optimal operating speed range of the main power source in different modes according to an embodiment of the present invention;

Fig. 4 is a configuration diagram of a parallel hybrid electric vehicle to which an embodiment of the present invention is applicable;

Fig. 5 is a configuration diagram of a parallel hybrid electric vehicle applicable to another embodiment of the present invention;

In the figure: 1. Step 1; 2. Step 2; 3. Step 3; 4. Step 4; 5. Step 5; 6. Step 6;

7. Step 7;

Ⅰ, engine; Ⅱ, clutch; Ⅲ, electric motor; Ⅳ, CVT; Ⅴ, power coupler.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, in which the same or similar symbols represent the same or similar physical quantities or physical quantities with the same or similar meanings throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "array" and "range" should be understood in a broad sense, for example, it can be a group of equally spaced numbers, or it can be randomly spaced For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific situations.

Since the basic structure of the parallel hybrid electric vehicle and the CVT is well known to those skilled in the art, it is not repeated here one by one, and only two typical configuration diagrams are given in accompanying drawings 3 and 4 .

A method for estimating driver demand torque of a CVT parallel hybrid electric vehicle according to an embodiment of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

The method shown in Figure 1 is an estimation method applicable to the required torque of a single-shaft parallel configuration HEV shown in Figure 4 . The method includes:

Step 1: Obtain the current driving mode of the car and the external characteristic data of the engine and electric motor. If there is only one power source for driving in the current driving mode, the composite external characteristics of the power system are equal to the external characteristics of the power source; if the current driving mode Both power sources are driving, then the composite external characteristics of the power system are equal to the sum of the external characteristics of the two power sources.

The detailed method is shown in Figure 2. If the current pure electric EV mode is used and only the electric motor is used for driving, then the composite external characteristics of the power system are equal to the external characteristic torque of the electric motor; In this mode, only the engine is driving, then the composite external characteristics of the power system are equal to the torque of the engine external characteristics; if the current mode is combined drive BHEV, and both power sources are driving, the composite external characteristics of the power system are equal to the external characteristics of the engine and The sum of the external characteristic torque of the electric motor; if there are other driving modes, the composite external characteristic is calculated according to the fact that all power sources participate in the driving of the vehicle.

Step 2: Divide the CVT speed ratio from the minimum value to the maximum value into an array i _g at a certain interval (the interval is a smaller value not less than the CVT speed ratio change sensitivity, such as 0.1). Then, the array S _ava of available speed ranges at the CVT input is obtained from the actual vehicle speed and each speed ratio. Then at any current vehicle speed, there is a speed ratio value _{is_ava} corresponding to any available speed S _ava .

Step 3: Based on the optimal operating speed range S _lim of the main power source defined in the control strategy of the current driving mode, limit the available speed range S _ava of the input end of the CVT at the current vehicle speed, that is, find the common range (intersection) of the two , to obtain the optimal operating speed range S _opt of the input end, and the speed ratio corresponding to each speed value is denoted as _{is_opt} .

Step 4: Interpolate the composite external characteristic TS curve of the power system under the current driving mode from each rotational speed in the optimal operating rotational speed range S _opt of the CVT input end, and obtain the CVT input torque range T _in ; then combine it with each rotational speed value S _opt The corresponding speed ratio i _{s_opt} obtains the output torque range T _out of the CVT.

Step 5: The CVT output torque range T _out under the real-time vehicle speed and drive mode is an array that changes with the speed ratio. The maximum value is obtained by calculating the MAX value of each torque value in the array, which is the current vehicle state (vehicle speed, drive mode), the power system can output the maximum torque T _max .

Step 6: Multiply the maximum output torque T _max of the power system under the current vehicle state by the accelerator pedal signal k to obtain the driver's pre-required torque T′ _req .

Step 7: Limit the rate of change of the pre-required torque value T' _req to obtain the exact value of the driver's real-time demanded torque T _req .

For the estimation method of the required torque of the dual-shaft parallel configuration hybrid electric vehicle shown in Figure 5, it is similar to the configuration method shown in Figure 4, with only some differences in step 1: after obtaining the current driving mode of the vehicle and the engine, After the motor external characteristic data, if only the electric motor works in the current drive mode, the composite external characteristic of the power system is equivalent to the result of the interaction between the external characteristic of the motor and the transmission ratio of the coupling device (the speed range is reduced and the torque range is expanded); if the current drive In the driving mode, only the engine is driving, the composite external characteristics of the power system are equal to the external characteristics of the engine; if both power sources are driving in the current driving mode, the composite external characteristics of the power system are equal to the external characteristics of the engine and the external characteristics of the motor and the coupling The sum of the results after the gear ratio of the device is applied.

For other single- and double-shaft parallel hybrid configurations, such as the case where the motor and the engine are coupled after the CVT, it can be realized by considering the influence of the speed ratio in a method similar to the above.

In summary, the real maximum output characteristics of the power system are obtained through the mode-based solution method for the composite external characteristics of the power system, and the calculation of the available speed S _ava at the input end of the CVT under each speed ratio, the optimal operating speed range of the main power source under different modes Limiting S _lim , the optimal operating speed range S _opt of the CVT input end is obtained, and then interpolated to obtain the input and output end torques corresponding to the external characteristics and the maximum output torque T _max achievable by the system, and finally the required torque can be obtained exact value.

The parts not mentioned in the present invention can be realized by adopting or referring to the prior art.

In the description of this specification, descriptions referring to the terms "one embodiment", "another embodiment", "single-axis parallel connection" or "two-axis parallel connection" mean that specific features and structures described in conjunction with this embodiment or example , step, method or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, steps, methods or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

Although terms such as "array", "range", "single-axis parallel", "two-axis parallel", "CVT", "power system" are used more frequently in this article, the possibility of using other terms is not excluded . These terms are used only for the purpose of describing and explaining the essence of the present invention more conveniently; interpreting them as any kind of additional limitation is against the spirit of the present invention.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (3)

1. A kind of 1. CVT parallel hybrid electrics operator demand's torque estimation method, it is characterised in that：Comprise the following steps：

   Step 1, the characteristics of CVT inputs being respectively positioned on according to motor, the engine in parallel for mixing power vehicle, different driving mould The situation that whether each power source participates in driving under formula can be different；First according to two power source external characteristics, using based on driving The compound external characteristics method for solving of dynamical system of pattern, the dynamical system maximum obtained under each input speed can input torque；

   Step 2, for CVT speed than can stepless change real-time the characteristics of, determine that CVT speed compares i_gArray of coverage, between array Chosen every according to computational accuracy demand, then as shown in formula (1), i is compared according to CVT speed by actual vehicle speed v_gArray of coverage is asked Solve the available rotating speed S of CVT inputs under current vehicle speed_avaScope, you can obtain and compare i with real-time speed and any speed_{s_ava}Corresponding Every speed S_ava；Namely according to current vehicle speed value v can obtain it is fast than and two arrays of rotating speed, and a pair of fast ratio and tachometer value 1 Should；

   <mrow> <mi>n</mi> <mo>=</mo> <mfrac> <mrow> <mi>v</mi> <mo>&amp;CenterDot;</mo> <msub> <mi>i</mi> <mn>0</mn> </msub> <mo>&amp;CenterDot;</mo> <msub> <mi>i</mi> <mi>g</mi> </msub> </mrow> <mrow> <mn>0.377</mn> <mi>r</mi> </mrow> </mfrac> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow>

   In formula, n is CVT input rotating speeds, unit rpm；i₀For speed ratio of main reducer；R is radius of wheel, unit m；

   Step 3, the different spy of scope is limited according to the higher optimal working speed of major impetus source efficiency under different driving pattern Point, the optimal operating rotational speed range of main power source based on current drive pattern obtain CVT inputs rotating speed limitation scope S_lim； Again by the available rotating speed S of CVT inputs under current vehicle speed_avaScope, the two common factor is sought, obtain currently available CVT inputs most Excellent working speed S_optScope, the corresponding fast ratio of each rotating speed are designated as i_{s_opt}；

   Step 4, by the optimal working speed S of CVT inputs_optIn the range of the current drive pattern of every speed interpolation under dynamical system Unite compound external characteristics T-S curves, obtain CVT input torque scopes T_in；In conjunction with every speed S_optThe corresponding fast ratio of value i_{s_opt}, obtain the exportable torque range T of CVT_out；

   Step 5, to the exportable torque range T of CVT under real-time speed, pattern_outInterior each torque value seeks MAX, obtains current vapour Under the speed and drive pattern state of car, the exportable torque T of true maximum of dynamical system_max；

   Step 6, by the maximum exportable torque T of dynamical system under current vehicle condition_maxDriver is tried to achieve with accelerator pedal signal k Pre- demand torque T_r'_eq；

   Step 7, to avoid gained operator demand torque from larger rapid fluctuation occur, to pre- demand torque value T_r'_eqChange Rate is limited, and obtains driver's real-time requirement torque T_req, prevent the rapid change because of demand torque from causing pattern switching frequent Or vehicle impact is spent greatly.
2. 2. a kind of CVT parallel hybrid electrics operator demand's torque estimation method according to claim 1, its feature It is：The method for solving of the compound external characteristics T-S curves of dynamical system in the step 1 based on drive pattern is, according to current The participation driving situation of power source under drive pattern, determine the part of the compound external characteristics of dynamical system；I.e. dynamical system is answered Closing external characteristics only includes participating in driving, the maximum output characteristic for the power source for having driving wheel driving force to export under present mode.
3. 3. a kind of CVT parallel hybrid electrics operator demand's torque estimation method according to claim 1, its feature It is：CVT speed in the step 2 compares i_gArray of coverage refers to the excursion of all gearratios achieved by CVT, is The preset parameter that CVT mechanical structures are determined；CVT inputs rotating speed limitation scope S in the corresponding step 3_limIt is Refer under current drive pattern, the optimal operating rotational speed range of the main power source defined in automobile control strategy；Pure electronic S under pattern_limIt is the scope below the optimal working speed of the desired motor of control strategy or rated speed, there is engine participation Other drive patterns under S_limFor the desired engine optimum operating rotational speed range of control strategy；And motor, engine are most Excellent operating rotational speed range is according to its efficiency/oil consumption MAP data scalings, to improve dynamical system economy；While the step 2~ According to real-time bus state and each fast ratio i in 4_g, gained can use rotating speed S_avaThe optimal working speed S of scope, input_optModel Enclose, input torque scope T_in, output torque scope T_outBe array form, and each speed/torque value respectively with each fast ratio i_{s_ava}、i_{s_opt}Correspond, thus its output characteristics can be obtained according to CVT input characteristics, and then finally give driver's Accurate demand.