CN117864095A - Hybrid powertrain drive control method incorporating energy management and torsional damping - Google Patents
Hybrid powertrain drive control method incorporating energy management and torsional damping Download PDFInfo
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- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W20/00—Control systems specially adapted for hybrid vehicles
- B60W20/10—Controlling the power contribution of each of the prime movers to meet required power demand
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- B60W2510/00—Input parameters relating to a particular sub-units
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Abstract
The invention relates to a hybrid power transmission system driving control method combining energy management and torsional vibration suppression, which belongs to the technical field of hybrid power automobiles and comprises the following steps: s1: the energy management controller distributes driving power of an engine motor according to the intention of a driver and the running state of the vehicle and determines a vehicle driving mode; s2: the hybrid controller selects a corresponding torsional vibration controller according to a driving mode and a switching state of the vehicle, and adds a motor active control torque command on the basis of the output of the energy management controller; s3: the motor controller, the engine controller and the speed change controller receive commands and control the rotating speed and the torque of the power source; s4: each component of the transmission system executes a torque rotating speed command issued by the controller; s5: the sensors of all parts of the transmission system detect the current running state of the vehicle and feed the current running state back to the upper-layer controller.
Description
Technical Field
The invention belongs to the technical field of hybrid electric vehicles, and relates to a hybrid power transmission system driving control method combining energy management and torsional vibration suppression.
Background
Under the general technical trends of high integration level, high power density, light weight and intelligent power of a new generation of hybrid power system, the quick response and good controllability of a motor enable the vibration reduction of a transmission system not to be limited to passive vibration reduction, and a hybrid power automobile can cancel a dual-mass flywheel. Through energy management and power coordination control of the hybrid power system, the fuel economy of the vehicle can be greatly improved, and the emission of harmful substances can be reduced. However, when the power management of the hybrid electric vehicle is improper and the coordination control is not in place, the vehicle can generate NVH problems in various working states due to the torque rotation speed vibration of the engine and the motor, the impact generated during mode conversion and other reasons, so that the comfort, the economy and the emission of the vehicle are affected. Therefore, the self-adaptive active vibration suppression method of the dual-mass flywheel is cancelled, becomes a hot topic for the research and development of the hybrid electric vehicle, and is highly valued by domestic scholars and industry.
In recent years, the students focus on the dynamic coordination control of active vibration reduction and torque disturbance compensation of feedback control and frequency correction, and both active vibration suppression methods can effectively attenuate the torsional vibration problem of the hybrid drive transmission system, but because the torsional vibration controller is not combined with energy management strategies, motor control, engine control and speed change control, and special torsional vibration controllers are required to be adopted for the torsional vibration problem of the hybrid drive transmission system under different driving modes and switching states, a control mode combining the energy management strategies and the torsional vibration suppression is required to be designed for carrying out targeted vibration suppression on the torsional vibration problem under the different driving modes.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a hybrid powertrain drive control method that combines energy management and torsional vibration suppression.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a hybrid powertrain drive control method that combines energy management with torsional vibration suppression, comprising the steps of:
s1: the energy management controller distributes driving power of an engine motor according to the intention of a driver and the running state of the vehicle and determines a vehicle driving mode;
s2: the hybrid controller selects a corresponding torsional vibration controller according to a driving mode and a switching state of the vehicle, and adds a motor active control torque command on the basis of the output of the energy management controller;
s3: the motor controller, the engine controller and the speed change controller receive commands and control the rotating speed and the torque of the power source;
s4: each component of the transmission system executes a torque rotating speed command issued by the controller;
s5: the sensors of all parts of the transmission system detect the current running state of the vehicle and feed the current running state back to the upper-layer controller.
Further, the step S1 specifically includes:
the energy management controller obtains the total required torque T according to the intention of the driver and the running state of the current vehicle r And the SOC value of the battery, and an energy management strategy is formulated according to the required torque, the SOC value range, the engine torque range and the motor torque range, the required torque is distributed and transmitted to the hybrid controller, the engine controller and the motor controller, and the vehicle driving mode is determined and transmitted to the hybrid controller and the speed change controller:
T r ＝T e_ref +T m_ref
wherein T is e_ref For engine target torque, T m_ref Target torque for the motor.
Further, the step S2 specifically includes:
the hybrid controller divides the driving mode of the hybrid electric vehicle into pure electric driving, independent engine driving and hybrid driving, and divides the driving mode switching into 6 modes according to whether the clutch state is changed in the mode switching process;
firstly, three states of pure electric drive, hybrid electric drive and pure electric-hybrid drive mode switching are listed as typical driving working conditions, and corresponding torsional vibration controllers are respectively designed; adopting a hybrid self-adaptive control algorithm to inhibit torsional vibration aiming at a pure electric driving mode; adopting a model predictive control algorithm to inhibit torsional vibration aiming at a hybrid power driving mode; model reference adaptation is employed to suppress torsional vibrations for pure-hybrid drive mode switching.
Further, for the pure electric mode, according to a dynamic model of a transmission system of the pure electric mode, a torsional vibration controller in an acceleration state is built based on a hybrid self-adaptive algorithm, and a transfer function of the system is obtained as follows:
wherein T is m * The target torque of the motor is input into the system; omega m The motor rotating speed is the output of the system; s represents the transfer function variable, a represents the pole equation coefficient, b 0 ～b 3 Represents the zero equation coefficient, p represents the control system, ζ p Representing the damping ratio, ω of the system p Representing a system pole;
the ideal model response function is:
the feedforward controller is expressed as:
wherein r represents feedforward control ζ r Represents the ideal damping ratio omega r Representing an ideal system pole;
the band-pass filter H(s) is expressed as:
where k represents a filter coefficient;
let-up input torque T m * =0, ω m The response to the input disturbance d is:
ω m ＝(1-H(s))G p (s)d
let k= (1- ζ) p )，ω m The expression is as follows:
where d represents system input disturbance.
Further, for the hybrid power mode, according to a dynamic model of a transmission system of the hybrid power mode, a torsional vibration controller in an acceleration state is built based on a model prediction algorithm, and a state space equation of the system is as follows:
the variables of the state variable x are respectively: the engine part angular velocity, the engine motor angular difference, the motor part angular velocity, the electric locomotive wheel angular difference and the wheel part angular velocity; the control quantity of the system is motor torque T m The disturbance variable is the engine output torque T e The system output is the angular speed of the motor part, the angular acceleration of the motor part, the angular speed of the vehicle body part of the wheel and the angular speed difference of the wheel of the electric locomotive;
discretizing a state equation of a continuous system, discretizing each coefficient of the state space equation according to a sampling period t, and adopting an approximate discretization formula for discretizing a coefficient matrix, wherein the discretization equation is as follows:
A f ＝AT s +I
B f ＝T s B
C f ＝C
wherein I is a 4×4 identity matrix, T s =0.001 is the sampling period time;
changing the discrete model to an incremental model:
wherein Vx (k) =x (k) -x (k-1), vu (k) =u (k) -u (k-1)
Constructing a prediction model: the state variables of the prediction system are:
Vx(k+1|k)＝A f Vx(k)+B f Vu(k)
L
wherein Δx (k+i|k) represents a time point k after the predicted time point i of the state of the system; a is that f Represents the predicted state variable coefficient, vx (k) represents the predicted state variable, B f Representing the predicted control variable coefficient, vu (k) representing the predicted control variable;
the system output prediction is:
y(k+1|k)＝C f Vx(k+1)+y(k)
＝C f A f Vx(k)+C f B f Vu(k)+y(k)
K
wherein y (k+ 1|k) represents a predicted output variable, C f Representing predicted output changesThe quantity coefficient, y (k) represents the output variable;
and (3) dynamically compensating an actuator: when the total delay time of the motor is T d In this case, the linear dynamic systematic rewrite is:
wherein T is de T is the ideal delay time de Numerically T s Integer multiples of (2);
adopting an explicit delay time compensation scheme; x (k+T) de I k) as a starting point of the prediction model, the expression is as follows:
the starting point of the predictive model is defined as:
the discretization system is expressed as:
establishing a related system optimization problem aiming at a required control target, and carrying out optimal control by solving a control system prediction model; the cost function is expressed as:
R c (k+1)＝[r(k+1) r(k+2) L r(k+N P )] T
wherein R is a reference sequence; q, R is a weight matrix; i Q (Y-R) c )|| 2 The torsional vibration fluctuation at the generator shaft is controlled to be as small as possible; r delta U 2 For adjusting the change rate of the power supply during the action;
controlling the motor torque increment within a reasonable range, and adding the following constraints on the basis of the original optimization problem:
y min (k)≤y(k)≤y max (k)
U min (k)≤U(k)≤U max (k)
-VU min (k)≤VU(k)≤VU max (k)
in combination with constraints, the objective function is rewritten as a standard form of the quadratic programming problem as follows:
wherein,
and solving the optimal value problem of the quadratic programming solution.
Further, for the "pure electric-hybrid electric" mode switching process, the mode switching process is divided into five phases, namely a clutch free displacement phase, a clutch slipping first phase, a clutch slipping second phase, a speed synchronization phase and a comprehensive participation phase, and a kinetic equation of each phase is built as follows:
wherein J is e And J m The rotational inertia of the engine part and the motor part respectively; omega e And omega m Representing the engine speed and the motor speed T, respectively e And T m Representing engine torque and motor torque, respectively; t (T) r The energy management system distributes the equivalent load torque of the motor output shaft according to the requirement of a driver; t (T) c Is the maximum friction torque that the clutch can provide, and is expressed as follows:
T c ＝μ c R c F b N c sign(ω m -ω e )
wherein mu is c 、R c 、F c 、N c The friction coefficient of the clutch plates, the effective radius of the clutch plates, the number of clutch plates, and the pressure on the clutch plates, respectively;
the dynamics model of the free displacement stage of the clutch is set as a reference model of the controller, and then the dynamics equation of the reference model is as follows:
wherein omega m Calculating the obtained required rotation speed for the reference model; t (T) m Torque is demanded for an equivalent driver;
set state variable x d ＝ω m Input variable u d ＝T m Output variable y d ＝ω m Disturbance variabled 1 ＝-T r The state space equation of the reference model is:
knowing the actual state x and the ideal state x of the system d The tracking error of the system and the reciprocal thereof are obtained as follows:
the dynamic error equation bringing the control system state space equation into the above-mentioned available system is:
definition matrix H m ∈R 2×2 For any Hurwitz matrix, then the above transform is:
wherein K is * ∈R 2×2 、L * ∈R 2×2 Their relationship is shown in the following formula:
in the formula I epsilon R 2×2 Is a unit matrix;
the control rate and the dynamic error of the control system are respectively as follows:
estimating unknown parameters of the system control rate, and setting an estimation error as follows:
in the method, in the process of the invention,and->Respectively K * And L * Is a function of the estimated value of (2);
the system unknown parameters in the control rate are replaced by their estimated values, and the adaptive control rate is obtained by:
aiming at the two modes of switching processes of 'engine single-pure electric drive' and 'hybrid-pure electric drive', the power switching is to cut off the output torque of an engine by separating a clutch between an engine and a motor group, and the generated torsional vibration problem is restrained by adopting a hybrid self-adaptive torsional vibration controller under a pure electric mode;
for the process of switching between the two modes of engine independent driving and engine independent-hybrid driving and hybrid-engine independent, the power switching is determined by whether the motor outputs effective torque or not, and a model predictive controller in a hybrid power mode is adopted to inhibit torsional vibration;
aiming at the mode mutual switching process of 'pure electric-hybrid driving' and 'pure electric-engine independent driving', the power switching is to drive a clutch to be engaged through a motor and start an engine to participate in power output, and a model reference controller in a pure electric-hybrid driving mode is adopted to inhibit torsional vibration.
Further, in step S3, the motor controller and the engine controller receive a target rotational speed and a target torque command transmitted by the energy management system through the CAN; the shift controller receives a mode select and switch command transmitted by the energy management system through the CAN.
Further, in step S4, the motor executes a torque rotation speed command issued by the motor controller; the engine executes a torque rotating speed command issued by an engine controller; the clutch executes an engagement, disengagement or switching command issued by the speed change mechanism; the transmission executes a gear selection and shift command issued by the transmission mechanism.
Further, in step S5, the speed sensor and the acceleration sensor distributed on each component of the transmission system record the current running state quantity of the vehicle, and transmit the current running state quantity to the motor controller, the engine controller, the speed change controller and the hybrid controller, and transmit the current running state quantity to the energy management controller through the CAN.
The invention has the beneficial effects that: the method combines energy management and transmission system torsional vibration control, and improves the applicability of torsional vibration control.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and other advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the specification.
Drawings
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in the following preferred detail with reference to the accompanying drawings, in which:
FIG. 1 is a flow chart of a control method;
FIG. 2 is a block diagram of a control method;
FIG. 3 is a schematic diagram of a driving mode;
fig. 4 is a torsional vibration controller selection schematic.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. It should be noted that the illustrations provided in the following embodiments merely illustrate the basic idea of the present invention by way of illustration, and the following embodiments and features in the embodiments may be combined with each other without conflict.
Wherein the drawings are for illustrative purposes only and are shown in schematic, non-physical, and not intended to limit the invention; for the purpose of better illustrating embodiments of the invention, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the size of the actual product; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numbers in the drawings of embodiments of the invention correspond to the same or similar components; in the description of the present invention, it should be understood that, if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc., that indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, but not for indicating or suggesting that the referred device or element must have a specific azimuth, be constructed and operated in a specific azimuth, so that the terms describing the positional relationship in the drawings are merely for exemplary illustration and should not be construed as limiting the present invention, and that the specific meaning of the above terms may be understood by those of ordinary skill in the art according to the specific circumstances.
The invention provides a hybrid power transmission system driving control method combining energy management and torsional vibration suppression, aiming at the problem of torsional vibration of a transmission system under the driving working condition of a P2 hybrid power automobile. Firstly, an energy management controller distributes driving power of an engine motor according to the intention of a driver and the running state of a vehicle, and determines a vehicle driving mode; then, designing a torsional vibration controller under typical working conditions, selecting a corresponding torsional vibration controller by a hybrid controller according to a driving mode and a switching state of the vehicle, and adding a motor active control torque command on the basis of the output of an energy management controller; then the motor controller, the engine controller and the speed change controller control the rotation speed and the torque of the power source according to the received command; and finally, detecting the current running state of the vehicle by using the sensors of all parts of the transmission system, and feeding back to an upper controller.
The method comprises the following specific steps:
1. energy management distributed power
As shown in fig. 2, the energy management controller can obtain the total required torque T according to the intention of the driver and the current running state of the vehicle r And the SOC value of the battery, and an energy management strategy is formulated according to the required torque, the SOC value range, the engine torque range and the motor torque range, the required torque is reasonably distributed and transmitted to the hybrid controller, the engine controller and the motor controller, and the vehicle driving mode is determined and transmitted to the hybrid controller and the speed change controller.
T r ＝T e_ref +T m_ref
Wherein T is e_ref For engine target torque, T m_ref Target torque for the motor.
2. Design of torsional vibration controller under typical working condition
The hybrid controller divides the driving mode of the P2 hybrid electric vehicle into pure electric driving, engine independent driving and hybrid driving. As shown in fig. 3, the driving mode switching can be divided into 6 forms according to whether the clutch state is changed during the mode switching. Firstly, three states of pure electric drive, hybrid electric drive and pure electric-hybrid drive mode switching are listed as typical driving working conditions, and corresponding torsional vibration controllers are respectively designed. Adopting a hybrid self-adaptive control algorithm to inhibit torsional vibration aiming at a pure electric driving mode; adopting a model predictive control algorithm to inhibit torsional vibration aiming at a hybrid power driving mode; model reference adaptation is employed to suppress torsional vibrations for pure-hybrid drive mode switching. The controller is specifically as follows:
(1) Pure electric mode
And constructing a torsional vibration controller in an acceleration state based on a hybrid self-adaptive algorithm according to a dynamic model of the drive system in a pure electric mode. Let the input of the system be the motor target torque T m * The output of the system being electricalEngine speed omega m The transfer function of the system can be deduced as:
setting an ideal model response function as follows:
the feedforward controller may be expressed as:
the control model comprises a feedforward part and a feedback part, and in order to achieve better control effect, different problems are combined for analysis, and an ideal damping ratio is generally used for replacing an actual damping ratio after the feedforward controller acts; the feedback controller can reduce the disturbance so that the control action is close to the ideal state. H(s) can thus be expressed as:
let-up input torque T m * =0, ω m The response to the input disturbance d is:
ω m ＝(1-H(s))G p (s)d
let k= (1- ζ) p )，ω m The expression can be as follows:
(2) Hybrid mode
And constructing a torsional vibration controller in an acceleration state based on a model prediction algorithm according to a dynamic model of the transmission system in the hybrid power mode. The state space equation of the system is:
the variables of the state variable x are respectively: the engine part angular velocity, the engine motor angular difference, the motor part angular velocity, the electric locomotive wheel angular difference and the wheel part angular velocity; the control quantity of the system is motor torque T m The disturbance variable is the engine output torque T e The disturbance quantity of the system is output as angular speed of a motor part, angular acceleration of the motor part, angular speed of a vehicle body part of a wheel and angular speed difference of an electric locomotive wheel.
1) Discretization
In order to design a vibration controller for model simulation, it is necessary to discretize a continuous system state equation and discretize each coefficient of a state space equation according to a sampling period t. An approximate discretization formula is used for discretizing the coefficient matrix, and the discretization formula is as follows:
A f ＝AT s +I
B f ＝T s B
C f ＝C
wherein I is a 4×4 identity matrix, T s =0.001 is the sampling period time.
To stabilize the system and reduce static errors, the discrete model described above may be further modified to an incremental model:
wherein Vx (k) =x (k) -x (k-1), vu (k) =u (k) -u (k-1).
2) Model prediction
The construction of the prediction mode is the core of the model prediction vibration damping controller. The main function of the prediction model is to enable the input and output tracks of the prediction model to be close to the given reference output as much as possible according to the optimal control sequence of each time. Therefore, the accuracy of the prediction model has important influence on the control result, and the state variables of the prediction system are as follows:
Vx(k+1|k)＝A f Vx(k)+B f Vu(k)
L
where Δx (k+i|k) represents a time point k after the predicted time point i of the state of the system.
The system output prediction is:
y(k+1|k)＝C f Vx(k+1)+y(k)
＝C f A f Vx(k)+C f B f Vu(k)+y(k)
K
3) Actuator dynamic compensation
When the total delay time of the motor is T d In this case, the linear dynamic systematic rewrite is:
wherein T is de T is the ideal delay time de Numerically T s Is an integer multiple of (a).
Using explicit delay time compensation schemes。x(k+T de I k) as a starting point of the prediction model, the expression is as follows:
the starting point of the predictive model is defined as:
the discretization system can be expressed as:
/>
4) Solving for
After the control system prediction model is constructed, relevant system optimization problems can be established for the required control targets. And carrying out optimal control by solving a control system prediction model. By adjusting the motor torque, the amplitude of the oscillations on the motor shaft can be reduced as much as possible, thereby reducing the speed differential between the motor and the tire. And thereby the purpose of active vibration reduction of the control system is realized. The cost function can be expressed as:
R c (k+1)＝[r(k+1) r(k+2) L r(k+N P )] T
wherein R is a reference sequence; q, R is a weight matrix; i Q (Y-R) c )|| 2 The torsional vibration fluctuation at the generator shaft is controlled to be as small as possible; r delta U 2 To prevent a motor torque from being excessively changed to form a new excitation source by adjusting the change rate of a power supply during operation, thereby generating new current resonance.
Controlling the motor torque increment within a reasonable range, and adding the following constraints on the basis of the original optimization problem:
y min (k)≤y(k)≤y max (k)
U min (k)≤U(k)≤U max (k)
-VU min (k)≤VU(k)≤VU max (k)
in conjunction with constraints, the objective function may be rewritten as a standard form of the quadratic programming problem as follows:
wherein,
/>
and solving the problem of solving the optimal value of the quadratic programming through a quadprog function carried by MATLAB software.
(3) "pure electric-hybrid" mode switching process
The mode switching process is divided into five stages, namely a clutch free displacement stage, a clutch slipping first stage, a clutch slipping second stage, a speed synchronization stage and a comprehensive participation stage, and a dynamics equation of each stage is built as follows:
wherein J is e And J m The rotational inertia of the engine part and the motor part respectively; omega e And omega m Representing the engine speed and the motor speed T, respectively e And T m Representing engine torque and motor torque, respectively; t (T) r The energy management system distributes the equivalent load torque of the motor output shaft according to the requirement of a driver; t (T) c Is the maximum friction torque that the clutch can provide, and can be expressed as follows:
T c ＝μ c R c F b N c sign(ω m -ω e )
wherein mu is c 、R c 、F c 、N c The friction coefficient of the clutch plates, the effective radius of the clutch plates, the number of clutch plates and the pressure on the clutch plates, respectively.
The dynamics model of the free displacement stage of the clutch is set as a reference model of the controller, and then the dynamics equation of the reference model is as follows:
wherein omega m Calculating the obtained required rotation speed for the reference model; t (T) m Torque is demanded for the equivalent driver.
Set state variable x d ＝ω m Input variable u d ＝T m Output variable y d ＝ω m Disturbance variable d 1 ＝-T r The state space equation of the reference model is:
knowing the actual state x and the ideal state x of the system d The tracking error of the system and the reciprocal thereof can be obtained as follows:
the dynamic error equation bringing the control system state space equation into the above-mentioned available system is:
definition matrix H m ∈R 2×2 For any Hurwitz matrix, the above equation can be transformed into:
wherein K is * ∈R 2×2 、L * ∈R 2×2 Their relationship is shown in the following formula:
in the formula I epsilon R 2×2 Is an identity matrix.
The control rate and the dynamic error of the control system are respectively as follows:
in the control rate, K * And L * Can not be directly obtained through calculation, so unknown parameters of the control rate of the system are required to be processedEstimating, namely setting an estimation error as:
in the method, in the process of the invention,and->Respectively K * And L * Is a function of the estimated value of (2);
the system unknown parameters in the control rate are replaced by their estimated values, and the adaptive control rate can be obtained as follows:
3. torsional vibration controller selection rules
As shown in fig. 4, different torsional controllers may be selected to control the driveline torsional response characteristics in different drive modes.
For the two modes of switching processes of 'engine single-pure electric drive' and 'hybrid-pure electric drive', the power switching is to cut off the output torque of the engine by separating a clutch between an engine and a motor group, and the required torque of the motor suddenly increases at the switching moment due to the sudden reduction of the whole vehicle driving torque at the separation moment, which is equivalent to the application of a step signal to the required torque of the motor, and the influence of the suddenly increased torque on a transmission system in the pure electric mode is the same. The problem of torsional vibration generated by this process can be suppressed using a hybrid adaptive torsional vibration controller in electric-only mode.
For the process of switching between the two modes of engine alone driving and engine alone-hybrid driving and hybrid-engine alone, the power switching is determined by whether the motor outputs effective torque or not, and during the switching between the two modes, the clutch is kept unchanged at all times, and the torsional vibration of the transmission system mainly comes from the fluctuation of the output torque of the engine, which is the same as the problem of the torsional vibration in the hybrid driving mode, so that the model predictive controller in the hybrid driving mode can be adopted for torsional vibration suppression.
In the two mode switching processes, torsional vibration of a transmission system comes from a slip stage of the clutch and output torque fluctuation of the engine, so that a model reference controller in a pure electric-hybrid power driving mode can be used for torsional vibration suppression.
4. Execution and feedback
The motor controller and the engine controller receive target rotating speed and target torque commands transmitted by the energy management system through the CAN; the shift controller receives a mode select and switch command transmitted by the energy management system through the CAN. The motor executes a torque rotating speed command issued by the motor controller; the engine executes a torque rotating speed command issued by an engine controller; the clutch executes an engagement, disengagement or switching command issued by the speed change mechanism; the transmission executes a gear selection and shift command issued by the transmission mechanism. The speed sensor and the acceleration sensor distributed on each component of the transmission system record the current running state quantity of the vehicle, and are transmitted to the motor controller, the engine controller, the speed change controller and the hybrid controller, and are transmitted to the energy management controller through the CAN.
Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the claims of the present invention.
Claims (9)
1. A hybrid powertrain drive control method that combines energy management and torsional damping, characterized by: the method comprises the following steps:
s1: the energy management controller distributes driving power of an engine motor according to the intention of a driver and the running state of the vehicle and determines a vehicle driving mode;
s2: the hybrid controller selects a corresponding torsional vibration controller according to a driving mode and a switching state of the vehicle, and adds a motor active control torque command on the basis of the output of the energy management controller;
s3: the motor controller, the engine controller and the speed change controller receive commands and control the rotating speed and the torque of the power source;
s4: each component of the transmission system executes a torque rotating speed command issued by the controller;
s5: the sensors of all parts of the transmission system detect the current running state of the vehicle and feed the current running state back to the upper-layer controller.
2. The hybrid powertrain drive control method combining energy management and torsional vibration suppression of claim 1, wherein: the step S1 specifically includes:
the energy management controller obtains the total required torque T according to the intention of the driver and the running state of the current vehicle r And the SOC value of the battery, and an energy management strategy is formulated according to the required torque, the SOC value range, the engine torque range and the motor torque range, the required torque is distributed and transmitted to the hybrid controller, the engine controller and the motor controller, and the vehicle driving mode is determined and transmitted to the hybrid controller and the speed change controller:
T r ＝T e_ref +T m_ref
wherein T is e_ref For engine target torque, T m_ref Target torque for the motor.
3. The hybrid powertrain drive control method combining energy management and torsional vibration suppression of claim 1, wherein: the step S2 specifically includes:
the hybrid controller divides the driving mode of the hybrid electric vehicle into pure electric driving, independent engine driving and hybrid driving, and divides the driving mode switching into 6 modes according to whether the clutch state is changed in the mode switching process;
firstly, three states of pure electric drive, hybrid electric drive and pure electric-hybrid drive mode switching are listed as typical driving working conditions, and corresponding torsional vibration controllers are respectively designed; adopting a hybrid self-adaptive control algorithm to inhibit torsional vibration aiming at a pure electric driving mode; adopting a model predictive control algorithm to inhibit torsional vibration aiming at a hybrid power driving mode; model reference adaptation is employed to suppress torsional vibrations for pure-hybrid drive mode switching.
4. A hybrid powertrain drive control method incorporating energy management and torsional damping as recited in claim 3, wherein: for the pure electric mode, a torsional vibration controller in an acceleration state is built based on a hybrid self-adaptive algorithm according to a dynamic model of a transmission system of the pure electric mode, and a transfer function of the system is obtained as follows:
wherein T is m * The target torque of the motor is input into the system; omega m The motor rotating speed is the output of the system; s represents the transfer function variable, a represents the pole equation coefficient, b 0 ～b 3 All represent zero equation coefficients, p represents the control system, ζ p Representing the damping ratio, ω of the system p Representing a system pole;
the ideal model response function is:
the feedforward controller is expressed as:
wherein r represents feedforward control ζ r Represents the ideal damping ratio omega r Representing an ideal system pole;
the band-pass filter H(s) is expressed as:
where k represents a filter coefficient;
let-up input torque T m * =0, ω m The response to the input disturbance d is:
ω m ＝(1-H(s))G p (s)d
let k= (1- ζ) p )，ω m The expression is as follows:
where d represents system input disturbance.
5. The hybrid powertrain drive control method combining energy management and torsional vibration suppression of claim 4, wherein: for a hybrid power mode, a torsional vibration controller in an acceleration state is built based on a model prediction algorithm according to a dynamic model of a transmission system in the hybrid power mode, and a state space equation of the system is as follows:
the variables of the state variable x are respectively: the engine part angular velocity, the engine motor angular difference, the motor part angular velocity, the electric locomotive wheel angular difference and the wheel part angular velocity; the control quantity of the system is motor torque T m The disturbance variable is the engine output torque T e The system output is the angular speed of the motor part, the angular acceleration of the motor part, the angular speed of the vehicle body part of the wheel and the angular speed difference of the wheel of the electric locomotive;
discretizing a state equation of a continuous system, discretizing each coefficient of the state space equation according to a sampling period t, and adopting an approximate discretization formula for discretizing a coefficient matrix, wherein the discretization equation is as follows:
A f ＝AT s +I
B f ＝T s B
C f ＝C
wherein I is a 4×4 identity matrix, T s =0.001 is the sampling period time;
changing the discrete model to an incremental model:
wherein Δx (k) =x (k) -x (k-1), Δu (k) =u (k) -u (k-1)
Constructing a prediction model: the state variables of the prediction system are:
wherein Δx (k+i|k) represents a time point k after the predicted time point i of the state of the system; a is that f Represents the predicted state variable coefficient, deltax (k) represents the predicted state variable, B f Represents a predictive control variable coefficient, and Δu (k) represents a predictive control variable;
the system output prediction is:
wherein y (k+ 1|k) represents a predicted output variable, C f Representing a predicted output variable coefficient, y (k) representing an output variable;
execution ofAnd (3) dynamically compensating: when the total delay time of the motor is T d In this case, the linear dynamic systematic rewrite is:
wherein T is de T is the ideal delay time de Numerically T s Integer multiples of (2);
adopting an explicit delay time compensation scheme; x (k+T) de I k) as a starting point of the prediction model, the expression is as follows:
the starting point of the predictive model is defined as:
the discretization system is expressed as:
establishing a related system optimization problem aiming at a required control target, and carrying out optimal control by solving a control system prediction model; the cost function is expressed as:
R c (k+1)＝[r(k+1) r(k+2) … r(k+N P )] T
wherein R is a reference sequence; q, R is a weight matrix; i Q (Y-R) c )|| 2 The torsional vibration fluctuation at the generator shaft is controlled to be as small as possible; r delta U 2 For adjusting the change rate of the power supply during the action;
controlling the motor torque increment within a reasonable range, and adding the following constraints on the basis of the original optimization problem:
y min (k)≤y(k)≤y max (k)
U min (k)≤U(k)≤U max (k)
-ΔU min (k)≤ΔU(k)≤ΔU max (k)
in combination with constraints, the objective function is rewritten as a standard form of the quadratic programming problem as follows:
wherein,
and solving the optimal value problem of the quadratic programming solution.
6. The hybrid powertrain drive control method combining energy management and torsional vibration suppression of claim 5, wherein: for the 'pure electric-hybrid power' mode switching process, the mode switching process is divided into five stages, namely a clutch free displacement stage, a clutch slipping first stage, a clutch slipping second stage, a speed synchronization stage and a comprehensive participation stage, and a kinetic equation of each stage is built as follows:
wherein J is e And J m The rotational inertia of the engine part and the motor part respectively; omega e And omega m Representing the engine speed and the motor speed T, respectively e And T m Representing engine torque and motor torque, respectively; t (T) r The energy management system distributes the equivalent load torque of the motor output shaft according to the requirement of a driver; t (T) c Is the maximum friction torque that the clutch can provide, and is expressed as follows:
T c ＝μ c R c F b N c sign(ω m -ω e )
wherein mu is c 、R c 、F c 、N c The friction coefficient of the clutch plates, the effective radius of the clutch plates, the number of clutch plates, and the pressure on the clutch plates, respectively;
the dynamics model of the free displacement stage of the clutch is set as a reference model of the controller, and then the dynamics equation of the reference model is as follows:
wherein omega m Calculating the obtained required rotation speed for the reference model; t (T) m Torque is demanded for an equivalent driver;
set state variable x d ＝ω m Input variable u d ＝T m Output variable y d ＝ω m Disturbance variable d 1 ＝-T r The state space equation of the reference model is:
knowing the actual state x and the ideal state x of the system d The tracking error of the system and the reciprocal thereof are obtained as follows:
the dynamic error equation bringing the control system state space equation into the above-mentioned available system is:
definition matrix H m ∈R 2×2 For any Hurwitz matrix, then the above transform is:
wherein K is * ∈R 2×2 、L * ∈R 2×2 Their relationship is shown in the following formula:
in the formula I epsilon R 2×2 Is a unit matrix;
the control rate and the dynamic error of the control system are respectively as follows:
estimating unknown parameters of the system control rate, and setting an estimation error as follows:
in the method, in the process of the invention,and->Respectively K * And L * Is a function of the estimated value of (2);
the system unknown parameters in the control rate are replaced by their estimated values, and the adaptive control rate is obtained by:
aiming at the two modes of switching processes of 'engine single-pure electric drive' and 'hybrid-pure electric drive', the power switching is to cut off the output torque of an engine by separating a clutch between an engine and a motor group, and the generated torsional vibration problem is restrained by adopting a hybrid self-adaptive torsional vibration controller under a pure electric mode;
for the process of switching between the two modes of engine independent driving and engine independent-hybrid driving and hybrid-engine independent, the power switching is determined by whether the motor outputs effective torque or not, and a model predictive controller in a hybrid power mode is adopted to inhibit torsional vibration;
aiming at the mode mutual switching process of 'pure electric-hybrid driving' and 'pure electric-engine independent driving', the power switching is to drive a clutch to be engaged through a motor and start an engine to participate in power output, and a model reference controller in a pure electric-hybrid driving mode is adopted to inhibit torsional vibration.
7. The hybrid powertrain drive control method combining energy management and torsional vibration suppression of claim 1, wherein: in the step S3, the motor controller and the engine controller receive a target rotating speed and a target torque command transmitted by the energy management system through the CAN; the shift controller receives a mode select and switch command transmitted by the energy management system through the CAN.
8. The hybrid powertrain drive control method combining energy management and torsional vibration suppression of claim 1, wherein: in the step S4, the motor executes a torque rotating speed command issued by the motor controller; the engine executes a torque rotating speed command issued by an engine controller; the clutch executes an engagement, disengagement or switching command issued by the speed change mechanism; the transmission executes a gear selection and shift command issued by the transmission mechanism.
9. The hybrid powertrain drive control method combining energy management and torsional vibration suppression of claim 1, wherein: in step S5, the speed sensor and the acceleration sensor distributed on each component of the transmission system record the current running state quantity of the vehicle, and the current running state quantity is transmitted to the motor controller, the engine controller, the speed change controller and the hybrid controller, and is transmitted to the energy management controller through the CAN.
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