CN115339353B

CN115339353B - Electric quantity balance control system and method based on WLTC working condition

Info

Publication number: CN115339353B
Application number: CN202110520176.XA
Authority: CN
Inventors: 陈川川; 叶欢; 谢凌云; 刘志恒
Original assignee: Shanghai Automobile Gear Works
Current assignee: Shanghai Automobile Gear Works
Priority date: 2021-05-13
Filing date: 2021-05-13
Publication date: 2024-12-17
Anticipated expiration: 2041-05-13
Also published as: CN115339353A

Abstract

A power balance control system and method based on the WLTC working condition, comprising: an input module, a SOC (battery power) storage module, a dynamic energy calculation module, a power balance identification module, a power balance penalty module and a power balance torque distribution module. The present invention aims at GB18352 National VI Regulation requiring that the power of a transition cycle and a confirmation cycle needs to meet the requirement that the energy change Δ _Eress of a WLTC driving cycle is less than 0.5% of the total energy E _total of the entire driving cycle, which can avoid differences in the driver's driving operation and the test bench, and improve the robustness of the test.

Description

Electric quantity balance control system and method based on WLTC working condition

Technical Field

The invention relates to a technology in the field of vehicle power control, in particular to an electric quantity balance control system and method based on a WLTC working condition based on GB18753 national six-emission cycle.

Background

With the gradual severity of emission requirements, the emission pressure of the whole vehicle manufacturer is gradually increased so as to meet the gradually increased national regulations. From state six, regulations have increased the demand for PHEV, HEV vehicle charge balancing. The energy variation delta _Eress of the required regulation WLTC driving cycle is less than 0.5% of the total driving cycle energy E _total, and different driving habits and different hubs can have great influence on the robustness of the test result, so that the electric quantity exceeds the requirement of the regulation, and the test fails.

The existing power balance control method has the defects that the existing power balance control method of the WLTC is used for carrying out power balance calculation based on the SOC fed back by the BMS, but the SOC fed back by the BMS is the integral settlement result of the current of the high-voltage battery based on time, the actual energy of the high-voltage system cannot be fed back, and the actual energy of the high-voltage system is the integral result of the power of the high-voltage battery system based on time.

The SOC fed back by the BMS cannot truly feed back the actual energy state of the battery, and after frequent charge and discharge of the battery, the SOC is easy to jump, if SOC is adopted to calculate the electric quantity balance, the experimental result is easy to exceed the requirement of regulations, and the experiment fails.

Disclosure of Invention

Aiming at the condition that the transition circulation is required by GB18352 national Six Codes rule and the electric quantity of the confirmation circulation needs to meet that the energy variation delta _Eress of the WLTC driving circulation is smaller than 0.5% of the total energy E _total of the whole driving circulation, the invention provides an electric quantity balance control system and an electric quantity balance control method based on WLTC working conditions, which can avoid the difference of driving operation of a driver and a test bed and improve the robustness of a test.

The invention is realized by the following technical scheme:

The invention relates to an electric quantity balance control system based on a WLTC working condition, which comprises an input module, an SOC (battery electric quantity) storage module, a dynamic Energy calculation module, an electric quantity balance identification module, an electric quantity balance punishment module and an electric quantity balance torque distribution module, wherein the dynamic Energy calculation module monitors the battery electric quantity in real time and performs battery electric quantity closed-loop control in a WLTC ultra-high speed section, according to the difference value between the electric quantity at the beginning of a driving cycle and the electric quantity of a closed-loop control section in which the WLTC ultra-high speed section is activated, torque dynamic compensation of an engine is performed to realize Energy balance of the whole driving cycle, the SOC storage module judges whether the battery electric quantity SOC is in a balance section at the moment of power-on of the whole vehicle and stores the battery electric quantity SOC in a VCU EEprom as an SOC initial value for dynamic Energy calculation, the dynamic Energy calculation module integrates time according to the current and voltage of a BMS (battery management system) fed back in real time in the vehicle operation process, and calculates the total Energy change BMS_energy Energy of the battery Energy according to the time, and meanwhile, the BMS_energy is divided by the total capacity of the battery, the SOC change is calculated, the corresponding SOC change is calculated, the electric quantity is detected by the difference value between the electric quantity of the electric quantity and the current electric quantity of the power of the battery is calculated when the current electric quantity is equal to the current electric quantity, the current electric quantity and the current electric quantity is equal to the current electric quantity, and the current electric quantity of the current electric quantity is calculated by the current electric quantity, and the current electric quantity is equal to the current value, and the current value of the CPUCPUCPL. When the torque penalty coefficient obtained by table lookup is equal to 0, the VCU table lookup is used for checking an original engine torque distribution strategy, the engine torque is directly applied to the driving wheel end, and the motor does not generate electricity and does not assist. When the torque penalty coefficient is smaller than 0, the VCU table look-up is used for correcting an engine torque distribution strategy, power generation compensation VCU_charge_MAP is adopted to perform engine torque distribution by adopting SOC_FAC+engine torque original MAP (1-SOC_FAC), when the SOC_FAC is larger than 0, the VCU table look-up is used for correcting the engine torque distribution strategy, discharge compensation VCU_charge_MAP is adopted to perform engine torque distribution by adopting SOC_FAC+engine torque original MAP (1-SOC_FAC), and dynamic coordination of SOC is realized through the functions, so that balance of vehicle energy is ensured.

The VCU (vehicle controller) in the input module receives the basic parameter information of the vehicle and provides information input for the later dynamic energy calculation module.

The basic parameter information of the vehicle comprises the current speed, the SOC of the power battery, the current voltage value, the whole vehicle high-voltage state, the opening degree of an accelerator pedal and the opening degree of a brake pedal.

The original engine torque distribution strategy in the electric quantity balance torque distribution module is based on an engine universal characteristic curve, an optimal working load point interval of the engine is determined, and engine torque in each gear is determined according to the rotation speed of an output shaft and the torque required by a wheel end.

The power generation compensation VCU_Charge_MAP in the electric quantity balance torque distribution module is based on the original engine torque distribution strategy to increase a certain engine torque, so that the power generation torque distributed to the motor is more.

The discharging compensation VCU_Discharge_MAP in the electric quantity balance torque distribution module is based on an original engine torque distribution strategy to reduce a certain engine torque, so that the motor needs to consume electric energy to meet the wheel end required torque.

Technical effects

The technical effects of the invention include:

1. The energy change of the battery is calculated in real time by utilizing the integral value of the charge and discharge current and the voltage of the battery in the running process of the vehicle, and the control on the battery electric quantity change is more accurate, so that the failure of the whole energy balance control caused by inaccurate battery electric quantity SOC fed back by the state difference of the battery is avoided. In addition, the SOC based on BMS feedback is the integral settlement result based on time of the high-voltage battery current, the actual energy of the high-voltage system cannot be fed back, and the system calculates the electric quantity balance through the integral result based on time of the power of the high-voltage battery, so that the test reliability is high.

2. And closed-loop control is adopted in the ultra-high speed section, a corresponding engine torque penalty coefficient is obtained by looking up a table according to the current SOC variation, and the engine torque is compensated, so that the whole WLTC electric quantity balance is achieved. Because the invention adopts closed-loop control in the final stage of WLTC test, the influence of the operation difference of the driver and the test bench can be avoided, and the control robustness is good.

Drawings

FIG. 1 is a flow chart of the present invention;

Fig. 2 is a schematic diagram of an embodiment.

FIG. 3 shows the results of the test of the examples.

Detailed Description

As shown in FIG. 1, the power balance control system based on WLTC working conditions in this embodiment comprises an input module, an SOC storage module, a dynamic energy calculation module, a power balance identification module, a power balance penalty module and a power balance torque distribution module.

The input module comprises whole vehicle state information acquired by a whole vehicle controller VCU, a motor controller MCU, a transmission controller TCU, an engine management system EMS, a battery management system BMS and the like. The whole vehicle controller VCU interacts with each unit controller through a whole vehicle communication CAN network, receives current basic parameter information of the vehicle, such as current vehicle speed, power battery SOC and current voltage value, total battery capacity, whole vehicle high-voltage state, accelerator pedal and brake pedal opening, current engine gear, motor gear and the like, and provides software input information for other modules.

The SOC storage module comprises a step of judging whether the battery electric quantity SOC is in a balance interval at the time of power-on of the whole vehicle, a step of carrying out normalization processing on the real SOC in an available electric quantity interval of the battery, and a step of storing the real SOC in VCU EEprom as an SOC initial value for dynamic energy calculation.

The dynamic energy calculating module comprises a battery instantaneous power calculating module, a power calculating module and a dynamic energy calculating module. The battery instantaneous power calculation module multiplies the current and the voltage of the BMS fed back in real time on the CAN in the running process of the vehicle to obtain the battery charging and discharging power at each moment. The power calculation module is used for integrating the battery charging and discharging power obtained by the battery instantaneous power calculation module with time and calculating to obtain the battery total Energy change BMS_energy. The dynamic Energy calculation module divides bms_energy by the total capacity of the battery, and calculates the SOC change corresponding to the Energy change.

The electric quantity balance identification module sets an SOC closed loop flag in the ultra-high speed section, when the VCU detects that the current vehicle speed is greater than the upper limit of the vehicle speed threshold, the VCU activates the closed loop once when the current vehicle speed is met, and when the current vehicle speed is lower than the lower limit of the vehicle speed threshold or exceeds a certain time, the closed loop control is exited.

And when the VCU is activated each time by the electric quantity balance punishment calculation module, a torque punishment coefficient is called, and different engine torque punishment coefficients SOC_FAC are obtained according to the SOC difference value table lookup calculated by the dynamic energy calculation module.

The electric quantity balance torque distribution module VCU obtains a torque penalty coefficient SOC_FAC by looking up a table according to the difference value of the SOC. When the torque penalty coefficient obtained by table lookup is equal to 0, the VCU table lookup is used for checking an original engine torque distribution strategy, the engine torque is directly applied to the driving wheel end, and the motor does not generate electricity and does not assist. When the torque penalty coefficient is smaller than 0, the VCU table look-up correction engine torque distribution strategy adopts the power generation compensation VCU_charge_MAP (-SOC_FAC) +the original MAP of the engine torque (1+SOC_FAC), engine torque distribution is carried out, when the SOC_FAC is larger than 0, the VCU table look-up correction engine torque distribution strategy adopts the Discharge compensation VCU_discharge_MAP (SOC_FAC) +the original MAP of the engine torque (1-SOC_FAC), engine torque distribution is carried out, dynamic coordination of SOC is realized through the functions, and balance of vehicle energy is ensured.

The original engine torque distribution strategy in the electric quantity balance torque distribution module is based on an engine universal characteristic curve, an optimal working load point interval of the engine is determined, and engine torque in each gear is determined according to the rotating speed and a gear end required torque gear shift line.

The discharge compensation VCU_ DISCHARGE _MAP in the electric quantity balance torque distribution module is based on the original engine torque distribution strategy to reduce a certain engine torque, so that the electric motor needs to consume electric energy to meet the wheel end demand torque.

The motor torque calculation module in the electric quantity balance torque distribution module is equal to the current wheel end required torque minus the torque transmitted to the wheel end by the engine torque, and then the motor torque calculation module is divided by the current motor gear speed ratio, namely (the wheel end required torque-the engine transmitted to the wheel end torque)/the motor gear speed ratio.

As shown in fig. 1, this embodiment relates to a method for controlling power balance based on WLTC working conditions, which specifically includes:

Step 1, storing the SOC, wherein the VCU detects that a driver activates the current driving cycle, and meanwhile, the SOC of the high-voltage battery is within a certain range [ A-2, A+2], and storing the actual BMS_ACT_SOC=A of the battery received at the moment in the VCU EEprom;

And 2, calculating dynamic Energy, namely starting timing according to the power-on enabling of the PEPS whole vehicle by a driver, integrating BMS actual Current BMS_Current and BMS actual Voltage BMS_Voltage received by a CAN communication network by a VCU to calculate total Energy BMS_energy of the battery, dividing the BMS_energy by the total capacity of the battery, and calculating SOC change delta _SOC corresponding to the Energy, wherein the power consumption is negative, and the power generation is positive.

And 3, performing SOC closed-loop identification, namely setting a flag for activating closed-loop control in an ultra-high speed section by the VCU according to the requirement delta _Eress/E_fuelcs of the WLTC rule CS mode electric quantity balance being smaller than 4%. When the VCU detects that the current vehicle speed is greater than 120kph, the VCU activates the closed loop once under the condition that the current vehicle speed is greater than 120kph, and when the current vehicle speed is less than 100kph or lasts for 30 seconds, the SOC closed loop identification is stopped.

And 4, calculating the SOC closed-loop penalty coefficient, namely calling a torque penalty coefficient once every time the VCU is activated, and penalizing different coefficients SOC_FAC according to the SOC difference calculated by the dynamic energy calculation module so as to compensate the increase and decrease of the torque.

And 5, SOC closed-loop torque compensation, wherein VCU looks up a torque penalty coefficient according to the difference value of the SOC. SOC difference Δ _SOC = [ -2-1.5 1.1.5 ] look-up SOC_FAC= [ -1-0.5.0.0.5 ]. When SOC_FAC is equal to 0, VCU looks up the original engine torque distribution strategy, and the engine torque can directly meet the wheel end torque demand, and the motor does not generate electricity and does not assist. When the SOC_FAC is smaller than 0, the VCU table look-up corrects an engine torque distribution strategy, and power generation compensation VCU_charge_MAP (-SOC_FAC) +engine torque original MAP (1+SOC_FAC) is adopted to distribute engine torque, and at the moment, the motor torque is obtained by dividing the motor torque by the gear speed ratio after subtracting the engine torque from the wheel end required torque. When the SOC_FAC is larger than 0, the VCU table look-up corrects an engine torque distribution strategy, and Discharge compensation VCU_discharge_MAP is adopted to distribute engine torque by adopting the initial MAP (1-SOC_FAC) of the engine torque, and meanwhile, the motor torque is equal to the wheel end required torque minus the engine torque transmitted to the wheel end torque and then divided by the motor gear speed ratio. Through the functions, dynamic coordination of the SOC is realized, and balance of vehicle energy is ensured.

As shown in fig. 2, WLTC test was performed according to GBT 19753-2013 light-duty hybrid electric vehicle energy consumption test method, and the laboratory temperature should be set to 23 ℃, allowing deviation ±5 ℃. Before starting, the vehicle is placed in the room at a temperature of 20-30 ℃ for at least 6 hours until the engine oil temperature and the coolant temperature are within a range of 23+/-2 ℃.

As shown in fig. 2, by the above control system and method based on WLTC electric quantity balance, 4 times of SOC closed loop control are activated in WLTC ultra-high speed section, when the SOC difference is greater than 0, the soc_fac coefficient obtained by table look-up in closed loop activation 2 stage is 0.5, the actual torque of the engine is equal to the original engine torque (1-0.5) +the engine torque value under discharge compensation MAP in the gear 6, and at this time, the motor torque is equal to the wheel end required torque minus the engine transmitted to the wheel end torque and divided by the motor gear speed ratio. When the difference value of the SOCs is smaller than 0, the SOC_FAC coefficient obtained by table lookup in the closed-loop activation 3 stage is-0.3, the actual torque of the engine is equal to the original engine torque (1-0.3) +the engine torque value under the discharge compensation MAP in the gear 6, and at the moment, the motor torque is equal to the wheel end required torque minus the torque transmitted to the wheel end by the engine and divided by the motor gear speed ratio. The SOC_FAC coefficient obtained by table lookup in the closed-loop activation 4 stage is-0.9, the actual torque of the engine is equal to the original engine torque (1-0.9) +the engine torque value under the discharge compensation MAP in the gear 6, and the motor torque is equal to the wheel end required torque minus the torque transmitted to the wheel end by the engine and divided by the motor gear speed ratio. The test result shows that the requirement of CS electric quantity balance can be met after the whole test is finished, and the oil consumption index is ideal.

Compared with the prior art, the control system and the control method have the advantages that through the control system and the control method, not only are the six discharge requirements of WLTC (wireless local area network) and the requirement delta _Eress/E_fuelcs of CS (circuit switched) mode electric quantity balance met, but also the consistency of test results after different testers conduct tests is high, and the control system and the control method are good in robustness and strong in applicability.

As shown in fig. 3, by comparing with the 10 sets of tests in the prior art, the control system and method according to the present invention can significantly improve the robustness and success of the test when the requirement Δ _Eress/E_fuelcs for balancing the electric quantity according to the CS mode is less than 4% (i.e. the consumed electric quantity in the table is less than the energy consumption limit value).

The foregoing embodiments may be partially modified in numerous ways by those skilled in the art without departing from the principles and spirit of the invention, the scope of which is defined in the claims and not by the foregoing embodiments, and all such implementations are within the scope of the invention.

Claims

1. A power balance control system based on WLTC working conditions is characterized by comprising an input module, an SOC storage module, a dynamic Energy calculation module, a power balance identification module, a power balance penalty module and a power balance torque distribution module, wherein the dynamic Energy calculation module monitors battery power in real time and performs battery power closed-loop control in a WLTC ultra-high speed section, and performs power balance of an engine according to the difference between the power at the beginning of a driving cycle and the power of a closed-loop control section where the WLTC ultra-high speed section is activated, torque dynamic compensation of the engine is performed, the SOC storage module judges whether the battery power SOC is in the balance section at the moment of power-on of the whole vehicle and stores the SOC in VCU EEprom as an SOC initial value calculated by dynamic Energy, the dynamic Energy calculation module calculates to obtain battery power variation BMS_energy by integrating time according to current and voltage of BMS fed back in real time on the CAN in the running process of the vehicle, and simultaneously divides BMS_energy by the total capacity of the battery, calculates SOC variation corresponding to the power variation, the SOC balance identification module sets a closed-loop detection SOC value at the ultra-high speed section, and performs power balance table lookup control on the power of the whole vehicle, and calculates a power table of the power of the vehicle when the current SOC is equal to the current value of the VCU, the power is equal to the torque penalty factor when the torque is equal to the current value of the VCU, the torque has a torque penalty factor is calculated by a value of the VCU, and the current value is equal to the torque value calculated by a value when the current value is equal to the value of the torque value calculated by a value of a value calculated by a lookup table, and the current value is equal to the torque value calculated by a value when the current value is equal to a value, and a torque value is equal to a value calculated by a value when the torque value calculated by a value and a penalty value is calculated by a value and is equal to a value calculated by a value and has a value calculated value. When the torque penalty coefficient is smaller than 0, VCU look-up table corrects the engine torque distribution strategy, power generation compensation VCU_charge_MAP is adopted to perform engine torque distribution by SOC_FAC+engine torque original MAP (1-SOC_FAC), when SOC_FAC is larger than 0, VCU look-up table corrects the engine torque distribution strategy, discharge compensation VCU_discharge_MAP is adopted to perform engine torque distribution by SOC_FAC+engine torque original MAP (1-SOC_FAC), dynamic coordination of SOC is realized through the functions, and balance of vehicle energy is ensured.

2. The WLTC-based power balance control system of claim 1, wherein said VCU in said input module receives vehicle base parameter information for providing information input to a subsequent dynamic energy calculation module;

3. The WLTC-operating-condition-based electric quantity balance control system of claim 1, wherein said original engine torque distribution strategy in said electric quantity balance torque distribution module is based on an engine universal characteristic curve, an optimal working load point interval of the engine is determined, and engine torque in each gear is determined according to an output shaft rotation speed and a wheel end demand torque.

4. The WLTC operating condition based Charge balance control system of claim 1, wherein said Charge balance torque distribution module generates power to compensate vcu_charge_map by adding a certain engine torque to said original engine torque distribution strategy, thereby increasing the generated torque distributed to said electric machine.

5. The WLTC-based power balance control system of claim 1, wherein said power balance torque distribution module is configured to reduce said Discharge compensation vcu_discharge_map by a predetermined amount based on said original engine torque distribution strategy, such that said electric machine consumes electric power to meet said wheel-end demand torque.