CN107826101A - A kind of series parallel hybrid power car threshold control strategy - Google Patents

Abstract

The invention discloses a logic threshold value control strategy of a serial hybrid electric passenger car. The strategy mainly includes 1) determining the switching rules between various working modes; 2) determining the component state control rules in different working modes; 3) determining the torque between the components of the power system in different working modes Assignment rules; 4) Build a Simulink model in Matlab and generate a control file. The test simulation in CRUISE software shows that this strategy can ensure that the supercapacitor has good charging-discharging characteristics and power balance characteristics under the condition of meeting the driving requirements of the vehicle, and realizes good distribution of torque. Compared with the actual vehicle operating data, The fuel consumption per 100 kilometers of the vehicle has been reduced by 5.57%.

Description

A Logical Threshold Control Strategy for Parallel Hybrid Electric Bus

technical field

The invention belongs to the field of control strategies for a hybrid electric passenger car, in particular to a logic threshold value control strategy.

Background technique

The existing vehicle control strategy is often affected by the simplicity and ease of implementation of its control rules and methods during design, thereby simplifying the control object and optimizing the control method, resulting in a single control target, incomplete control methods and Therefore, developing a more comprehensive, practical and efficient vehicle control strategy to better realize the superior performance of safety, reliability, energy saving and environmental protection of hybrid electric buses is still an urgent problem to be solved.

The vehicle control strategy of a hybrid electric bus is essentially a method of controlling the distribution and management of energy and optimizing the work of the power system. It can reflect the driver's response to the accelerator pedal or brake pedal according to the actual road conditions. Start, calculate the energy required for the vehicle to run, and then manage the power flow through reasonable planning of mechanical transmission and electric transmission, distribute energy output to the power source, and coordinate the work of various components to complete the expected control goals, such as the least fuel consumption Consumption, minimum emissions and excellent drivability, etc.

With the continuous development of hybrid technology conditions, hybrid hybrid buses have become the key models of new energy vehicle research in China. Under the current situation of urban traffic congestion and serious environmental pollution, it is better to promote urban buses to achieve energy saving and emission reduction. , has great practical development value.

The present invention takes a domestic coaxial hybrid hybrid electric bus as the research object, and on the basis of its hybrid system analysis, proposes a logic threshold value control strategy for the hybrid hybrid passenger car. So far, Have not yet seen the research report relevant to the present invention.

Contents of the invention

The purpose of the present invention is to propose a logical threshold for a hybrid hybrid bus in order to better realize the safety, reliability, energy saving, and environmental protection of the hybrid hybrid bus, and to realize the comprehensive, practical and efficient control of the whole vehicle. Value control strategy.

The purpose of the present invention can be achieved through the following technical solutions.

A logic threshold value control strategy for a series-connected hybrid electric passenger car is characterized in that it comprises the following steps:

1) The driver's operation on the accelerator/brake pedal, the state of charge SOC of the power supply, the current vehicle speed and the required torque of the vehicle are selected as the basic parameters for vehicle control;

2) Determine different working modes according to the parameters in step 1);

3) Determine the automatic clutch and engine status according to the parameters in step 1);

4) Determine the torque distribution among the assembly components of the power system according to the parameters in step 1);

5) According to the designed control rules, build the corresponding Simulink model and generate control files for the vehicle logic threshold control strategy in Matlab software.

According to claim 1, a logic threshold value control strategy for a series hybrid electric bus, characterized in that, in said step 1), the driver has two operations of depressing the accelerator pedal or depressing the brake pedal, and the power supply The state of charge SOC has upper and lower limits, SOC_high and SOC_low respectively represent the upper and lower limits of the set super capacitor power, and set SOC_high=0.8, SOC_low=0.4; the current vehicle speed has a control value, which is set according to the idle speed of the engine; The required torque of the vehicle is calculated from the current output torque of the main drive motor and the opening of the accelerator pedal.

According to claim 1, a logic threshold control strategy for a series hybrid electric bus, characterized in that the working modes in step 2) include pure motor drive mode, ISG motor power generation and motor drive mode, engine There are 6 working modes: independent drive mode, combined drive mode, engine drive and power generation mode, and regenerative braking mode.

According to claim 1, a logic threshold value control strategy for a series hybrid electric bus, characterized in that, in said step 3), the automatic clutch has two states of disengagement and closure, and it is stipulated that "0" represents the disengagement state, "1" represents the closed state, and Clutch_Stage is used to represent the state of the clutch; the engine has two states: off/start, and "0" is specified to represent the closed state, "1" represents the start state, and Engine_Switch is used to represent the state of the engine.

According to claim 1, a logic threshold value control strategy for a series hybrid electric bus, characterized in that the torque distribution in step 4) includes two types of driving torque distribution and regenerative braking torque distribution.

According to claim 5, a logic threshold value control strategy for a series hybrid electric vehicle is characterized in that, for the drive torque, it is assumed that the opening degree of the accelerator pedal is A (%):

T _req ＝A×T _max ＝A×(T _{e_max} +T _{m_max} )

In the formula, T _req is the driving torque required by the vehicle (N m); T _max is the maximum torque that the vehicle can output at the current speed (N m); T _{e_max} is the output torque that the engine can output at the current speed Maximum torque (N m); T _{m_max} is the maximum torque (N m) that the main drive motor can output at the current speed;

For regenerative braking torque:

In the formula, T _{m_brake} is the regenerative braking torque output by the main drive motor (N m); -T _{m_max} is the maximum negative torque output by the main drive motor at the current vehicle speed (N m); A is the brake pedal open Spend(%).

Compared with the prior art, the present invention has the following advantages:

Through the driver's operation on the accelerator/brake pedal, etc., the driving intention information is identified according to the preset rules, the working mode, the state of the automatic clutch and the engine are determined, and then the required driving or braking torque is calculated and calculated. Allocation; the test simulation in CRUISE software shows that this strategy can ensure that the supercapacitor has good charge-discharge characteristics and power balance characteristics under the condition of meeting the vehicle driving requirements, and achieve good torque distribution, which is consistent with the actual vehicle operating data. Compared with that, the fuel consumption per 100 kilometers of the vehicle is reduced by 5.57%.

Description of drawings

Fig. 1 is a logical threshold value control strategy model established by the present invention.

Fig. 2 is a flow chart of switching control of different working modes in the present invention.

Fig. 3 is a flow chart of regenerative braking torque distribution control in the present invention.

Fig. 4 is an input signal pre-processing module model established by the present invention.

Fig. 5 is a torque distribution control module model established by the present invention.

Figure 6 is a schematic diagram of the power system of a hybrid hybrid bus.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific examples.

In combination with Fig. 6, compare the flow chart 2 to determine different working modes. If the driver depresses the accelerator pedal, it means that the vehicle has a drive or acceleration demand, then the required torque of the vehicle is calculated according to the accelerator pedal opening:

T _req ＝A×T _max ＝A×(T _{e_max} +T _{m_max} )

In the formula, T _req is the driving torque required by the vehicle (N m); T _max is the maximum torque that the vehicle can output at the current speed (N m); T _{e_max} is the output torque that the engine can output at the current speed Maximum torque (N·m); T _{m_max} is the maximum torque (N·m) that the main drive motor can output at the current vehicle speed.

Compare the calculated torque with the maximum/minimum output torque of the engine (obtained from the look-up table), and combine with the current SOC of the supercapacitor to determine the working mode.

If the required torque of the whole vehicle is lower than the minimum output torque of the engine, and the SOC of the supercapacitor is at a medium-to-high level, then the engine does not need to be started, and is driven by the main drive motor alone, that is, the pure motor drive mode; if SOC<SOC_low at this time, then, It is necessary to control the engine to start, the engine drives the ISG to charge the super capacitor, and then the main drive motor alone drives the vehicle, that is, the ISG motor generates power and the motor drives the mode.

If the required torque of the vehicle is higher than the minimum output torque of the engine but lower than the maximum output torque, then the engine needs to be started. If the SOC level is high, the engine only needs to output torque to drive the vehicle alone, that is, the engine alone drive mode; If SOC<SOC_high, in order to maintain better power balance characteristics, the engine needs to output part of the torque for charging, which is the engine driving and charging mode.

If the required torque of the whole vehicle is higher than the maximum output torque of the engine, it is necessary to control the engine and the main drive motor to drive the vehicle at the same time, that is, the joint drive mode.

If the driver depresses the brake pedal, it means that the vehicle has a need for braking and deceleration, that is, the regenerative braking mode; if there is no driving signal and no braking signal, the vehicle will coast.

According to the idling speed of the engine of the hybrid power system studied is 700r/min, which is converted into a vehicle speed of 21km/h, then 21km/h is selected as the control value of the vehicle speed condition, considering that there is a slipping state in the process of the clutch from separation to engagement , set the vehicle speed between 18~21km/h, the clutch will slip, that is hysteresis.

It is stipulated that the automatic clutch has two states of separation/closing, and "0" represents the separation state, "1" represents the closed state, and Clutch_Stage represents the state of the clutch; the engine has two states of shutdown/start, and "0" represents the closed state. "1" represents the starting state, and Engine_Switch represents the state of the engine.

Then the state control rules of the clutch and the engine are:

If the vehicle speed is ≥21km/h, Clutch_Stage=1, Engine_Switch=1;

If 21km/h≥vehicle speed≥18km/h, hysteresis;

If the vehicle speed is <18km/h and SOC≥0.6 (medium to high level), Clutch_Stage＝0, Engine_Switch＝0;

If the vehicle speed is <18km/h and at this time 0.6>SOC≥0.4, hysteresis;

If the vehicle speed is <18km/h and SOC<0.4 at this time, Clutch_Stage＝0, Engine_Switch＝1;

Drive torque distribution rules:

When Clutch_Stage=0 (automatic clutch disengagement):

If SOC≥0.4, then T _m =T _req , T _e =T _isg =0;

If SOC<0.4, then T _e =-T _isg =T _{e_max} , T _m =T _req ;

When Clutch_Stage=1 (automatic clutch closed):

If T _{req ≥T e_max} and SOC≥0.4, then T _e =T _{e_max} , T _m =T _req -T _{e_max} , T _isg =0;

If T _{req ≥T e_max} and SOC<0.4, then T _e =T _{e_max} , T _m =(T _req -T _{e_max} )×0.5, T _isg =0;

If T _{e_min} ≤T _req <T _{e_max} and SOC≥0.8, then T _e =T _req , T _m =T _isg =0;

If T _{e_min} ≤T _req <T _{e_max} and 0.4≤SOC<0.8, then T _e =T _{e_max} , T _m =0, T _isg =T _req -T _{e_max} ;

If T _{e_min} ≤T _req <T _{e_max} and SOC<0.4, then T _e =T _{e_max} , T _m =0, T _isg =T _req - T _{e_max} ;

If T _req <T _{e_min} and SOC≥0.8, then T _e =T _isg =0, T _m =T _req ;

If T _req <T _{e_min} and 0.4≤SOC<0.8, then T _e =T _{e_min} , T _m =0, T _isg =T _req -T _{e_min} ;

If T _req <T _{e_min} and SOC<0.4, then T _e =T _{e_min} , T _m =0, T _isg =T _req −T _{e_min} . In the formula, T _req is the driving torque required by the vehicle (N m); T _{e_max} is the maximum output torque of the current engine (N m); T _{e_min} is the minimum output torque of the current engine (N m) ; T _e is the target operating torque of the engine (N m); T _m is the target operating torque of the main drive motor (N m); T _isg is the target operating torque of the ISG (N m).

Combining with Figure 6 to compare the flow chart 3 and the actual operation of the hybrid hybrid bus under study, only when the vehicle speed is higher than 10km/h and the SOC value is less than its upper limit value, the regenerative braking mode is used for energy recovery. The drive motor outputs negative torque, works as a generator to charge the supercapacitor, and does not recover energy in other states.

In order to better maintain the power balance of the super capacitor, the engine auxiliary power generation method can be used to achieve a better charging effect; if the SOC of the super capacitor is <SOC_low during regenerative braking, then not only the main drive motor is used to output negative torque to generate power , and start the engine to drive the ISG to generate electricity to increase the speed of charging the supercapacitor and quickly increase its SOC value.

The regenerative braking torque distribution rule is:

When 0.4≤SOC<0.8, there is no need to start the auxiliary power generation of the engine:

If the brake pedal opening A≥50%, then T _{m_brake} = -T _{m_max} ;

If the brake pedal opening A<50%, then T _{m_brake} = -T _{m_max} × A × 0.2;

When SOC<0.4, start the engine and ISG auxiliary power generation:

If the brake pedal opening A≥50%, then T _{m_brake} =-T _{m_max} , T _e =T _{e_min} , T _isg =-T _{e_min} ;

If the brake pedal opening A<50%, then T _{m_brake} =-T _{m_max} ×A×0.2, T _e =T _{e_min} , T _isg =-T _{e_min} ;

In the formula, T _{m_brake} is the regenerative braking torque output by the main drive motor (N m); -T _{m_max} is the maximum negative torque output by the main drive motor at the current vehicle speed (N m); A is the brake pedal open T _{e_min} is the minimum output torque of the current engine (N·m); T _e is the target operating torque of the engine (N·m); T _isg is the target operating torque of the ISG (N·m).

According to the designed torque distribution scheme and control rules, a Simulink model of the logic threshold value vehicle control strategy is built in Matlab, as shown in Figure 1. The model consists of an input signal pre-processing module and a torque distribution control module. The input control signals of the entire control strategy are current vehicle speed, super capacitor SOC, main drive motor speed, accelerator (accelerator) pedal opening and brake (brake) pedal opening; output control signals are engine output, main drive motor output, ISG Motor output, engine switch state and automatic clutch state, this model can realize the control of four components including engine, main drive motor, ISG motor and automatic clutch.

The input signal pre-processing module is the signal processing before the torque distribution. It mainly performs certain calculations or table look-up processing on the input signal to obtain some torque variables used in the torque distribution module, and completes the state judgment of the automatic clutch and the engine. Control; as shown in Figure 4, the input signal pre-processing module includes two parts: an automatic clutch/engine control module and a torque calculation module.

The automatic clutch/engine control module judges the disengagement/closing state of the clutch and the start/stop state of the engine at the next moment according to the current vehicle speed and the SOC of the super capacitor, and is equipped for the torque distribution of the power system; it mainly includes the vehicle speed condition judgment mode and SOC condition judgment mode, built in full accordance with the control rules introduced earlier.

The torque calculation module calculates the torque required for the vehicle to run according to the current output torque of the main drive motor and the opening of the accelerator pedal, and calculates the current maximum/minimum output torque of the engine and the main drive motor through a series of table lookups. The maximum output torque of the ISG and the maximum output torque of the ISG and other parameters, and these torque parameters are transmitted to the subsequent modules for torque distribution; the data sources of the five look-up modules (Look_Up module) are the engine and the main drive motor and universal characteristic data of ISG motors.

As shown in Figure 5, the torque distribution control module includes a vehicle operating mode determination module, a driving torque distribution module, a regenerative braking torque distribution module, a coasting control module and a parking control module.

The working mode judgment module judges the driver's intention according to the current vehicle speed, accelerator/brake pedal opening and other signals, and determines the working mode of the vehicle; when the accelerator pedal opening of the bus is not zero, that is, when there is an acceleration signal, the vehicle runs In the driving mode, the distribution of the driving torque is carried out; when the brake pedal opening of the passenger car is not zero, that is, when there is a braking signal, and the vehicle is running in the braking mode, the distribution of the regenerative braking torque is carried out; Both the accelerator pedal and the brake pedal are inactive, that is, when there is no acceleration signal or brake signal, the current vehicle state is judged according to the vehicle speed. If the vehicle speed is not 0, the vehicle is in the coasting control mode, otherwise the vehicle stops.

The driving torque distribution module and the regenerative braking torque distribution module are the core of the entire logic threshold control strategy, which respectively embody the previously designed driving torque distribution rules and regenerative braking torque distribution rules; the two modules It also includes control modules for the three power components of the engine, the main drive motor and the ISG motor, respectively controlling the torque output of the three; the coasting control module judges whether regenerative braking energy recovery is required based on the current vehicle speed and the SOC of the super capacitor , if necessary, control the main drive motor to output negative torque to recover energy.

It should be understood that the present invention is not limited to the logic threshold control strategy of the hybrid electric bus in the above-mentioned specific embodiments, and those skilled in the art can also make equivalent deformations or Modifications, these equivalent deformations or modifications are all included within the scope defined by the claims of the present application.

Claims (6)

1. a kind of logic threshold value control strategy of series hybrid electric passenger car, it is characterized in that, comprises the following steps: 1) Select the driver's operation on the accelerator/brake pedal, the state of charge SOC of the power supply, the current vehicle speed and the required torque of the vehicle as the basic parameters for vehicle control; 2) Determine different working modes according to the parameters in step 1); 3) Determine the automatic clutch and engine status according to the parameters in step 1); 4) Determine the torque distribution among the assembly components of the power system according to the parameters in step 1); 5) According to the designed control rules, build the corresponding Simulink model and generate control files for the vehicle logic threshold control strategy in Matlab software. 2. A logic threshold value control strategy for a series-connected hybrid electric bus according to claim 1, characterized in that, in the step 1), the driver has two operations of depressing the accelerator pedal or depressing the brake pedal , the power state of charge SOC has upper and lower limits, SOC_high and SOC_low respectively represent the upper and lower limits of the super capacitor power, and set SOC_high=0.8, SOC_low=0.4; the current vehicle speed has a control value, set according to the idle speed of the engine The required torque of the vehicle is calculated from the current output torque of the main drive motor and the opening of the accelerator pedal. 3. A logic threshold value control strategy for a series hybrid electric bus according to claim 1, characterized in that the working modes in step 2) include pure motor drive mode, ISG motor power generation and motor drive mode , 6 working modes: single engine drive mode, combined drive mode, engine drive and power generation mode and regenerative braking mode. 4. A logic threshold value control strategy for a hybrid hybrid bus according to claim 1, characterized in that the automatic clutch in step 3) has two states of disengagement and closure, and "0" stands for disengagement State, "1" represents the closed state, use Clutch_Stage to represent the state of the clutch; the engine has two states: off/start, stipulate that "0" represents the closed state, "1" represents the start state, and use Engine_Switch to represent the state of the engine. 5. A logic threshold value control strategy for a series-connected hybrid electric bus according to claim 1, characterized in that, the torque distribution in step 4) includes both driving torque distribution and regenerative braking torque distribution. kind. 6. A kind of logic threshold value control strategy of series hybrid electric passenger car according to claim 5, it is characterized in that, for driving torque, it is assumed that the degree of opening of the accelerator pedal is A (%): T _req ＝A×T _max ＝A×(T _{e_max} +T _{m_max} ) In the formula, T _req is the driving torque required by the vehicle (N m); T _max is the maximum torque that the vehicle can output at the current speed (N m); T _{e_max} is the output torque that the engine can output at the current speed Maximum torque (N m); T _{m_max} is the maximum torque (N m) that the main drive motor can output at the current speed; For regenerative braking torque: In the formula, T _{m_brake} is the regenerative braking torque output by the main drive motor (N m); -T _{m_max} is the maximum negative torque output by the main drive motor at the current vehicle speed (N m); A is the brake pedal open Spend(%).