Torque distribution method for ECVT mode of hybrid vehicle model, and hybrid vehicle

Abstract

A torque distribution method for an ECVT mode of a hybrid vehicle model, and a hybrid vehicle. The method comprises: on the basis of vehicle operating conditions and the state of a vehicle power system, determining a total engine power demand; on the basis of the total engine power demand, the difference between the current power level and a target power level of a high-voltage battery, the coolant temperature of an engine, an atmospheric pressure, and a vehicle speed, determining a final target rotational speed of the engine; and on the basis of the total engine power demand, the final target rotational speed of the engine, and an actual rotational speed of the engine, determining a torque distribution for the engine, a generator, and a driving motor.

Description

A torque distribution method in ECVT mode of hybrid vehicle and hybrid vehicle

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The embodiments of this application are based on and claim the priority of Chinese patent application with application number 202311036431.9 and application date August 15, 2023. The entire contents of the Chinese patent application are hereby introduced into the embodiments of this application as a reference. Technical Field

[0003] The present invention belongs to the technical field of torque distribution of hybrid vehicles, and particularly relates to a torque distribution method in an ECVT mode of a hybrid vehicle and a hybrid vehicle. Background Art

[0004] Hybrid vehicles are becoming an increasingly common vehicle type. Figure 1 shows the power and electric power transmission path for hybrid vehicles in ECVT mode. The power transmission path is as follows: the engine (ICE) is connected to the planetary carrier of the planetary gear mechanism, the generator (GEN) is connected to the sun gear of the planetary gear mechanism, the wheels are connected to the outer ring gear of the planetary gear mechanism through a series of gears, and the drive motor (Motor) is connected to the wheels through a series of gears. In this mode, the drive motor is connected to the wheels through a series of reduction gears, and the outer ring gear of the planetary gear mechanism is also connected to the wheels through a series of reduction gears.

[0005] The electric power transmission path is: the charging and discharging state of the battery is determined by the sum of the electric power of the generator and the drive motor. When the sum of the electric power of the generator and the drive motor is greater than zero, the battery is in a discharging state, and the discharge power is equal to the sum of the electric power of the generator and the drive motor; when the sum of the electric power of the generator and the drive motor is less than zero, the battery is in a charging state, and the charging power is equal to the sum of the electric power of the generator and the drive motor; when the sum of the electric power of the generator and the drive motor is equal to zero, the battery is in a balanced state, and the high-voltage battery is neither charging nor discharging.

[0006] Torque distribution in hybrid vehicles is central to vehicle control, requiring tailored torque distribution based on varying operating conditions. Currently, conventional torque distribution is based on vehicle speed, driver torque demand, and other operating conditions, resulting in poor fuel economy and NVH (Noise, Vibration, and Harshness) performance.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a torque distribution method in the ECVT mode of a hybrid vehicle and a hybrid vehicle, so as to improve the fuel economy and NVH performance of the vehicle while ensuring that the driver's needs are correctly implemented.

[0009] The technical solutions of the present invention are as follows:

[0010] A method for distributing torque in an ECVT mode of a hybrid vehicle, used in an electronic device of the vehicle, comprises the following steps:

[0011] Determine the total engine power requirement based on the vehicle's operating conditions and power system status;

[0012] The final target engine speed is determined based on the total engine power demand, the difference between the current and target power levels of the high-voltage battery, engine water temperature, atmospheric pressure, and vehicle speed.

[0013] The torque distribution among the engine, generator and drive motor is determined based on the total engine required power, the final target engine speed and the actual engine speed.

[0014] As a second aspect of the present invention, a system for implementing the torque distribution method in the ECVT mode of a hybrid vehicle is further provided, comprising:

[0015] The engine power requirement module is used to determine the total engine power requirement based on the vehicle operating conditions and power system status;

[0016] The engine final target speed module is used to determine the engine final target speed based on the total engine power demand, the difference between the current power level of the high-voltage battery and the target power level, the engine water temperature, the atmospheric pressure and the vehicle speed;

[0017] The torque distribution module is used to determine the torque distribution of the engine, generator and drive motor based on the total engine required power, the engine's final target speed and the engine's actual speed.

[0018] As a third aspect of the present invention, a hybrid vehicle is further provided, which adopts any one of the above-mentioned torque distribution methods in the ECVT mode of the hybrid vehicle type.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] The present invention fully considers factors such as vehicle operating conditions, vehicle power system status and environmental changes, and designs a torque distribution method under ECVT mode. Different torque distribution is performed under different vehicle operating conditions, vehicle power system status and environmental factors, ensuring that the fuel economy and NVH performance of the vehicle are improved while the driver's needs are correctly implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a diagram of the power and electric power transmission path in the ECVT mode of a hybrid vehicle;

[0022] FIG2 is a flow chart of the torque distribution method in the ECVT mode of a hybrid vehicle;

[0023] FIG3 is a schematic diagram of the engine operating power efficiency area. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0025] The present invention provides a torque distribution method for a hybrid vehicle in ECVT mode, as shown in FIG2 , which determines the torque distribution of the engine, generator, and drive motor in ECVT mode through three steps.

[0026] The first step is to determine the total engine power requirement P according to the vehicle operating conditions and power system status. TotalEngine .

[0027] (1) Driver demand power P DriverRequest Determination of (unit kW): Assume that the driver's wheel side torque T is required at a certain moment TorqieRequestOnWheel 1000Nm, vehicle speed V VehicleSpeed The tire radius R of a certain vehicle model is 40km / h. WheelRadius =0.36m, then substitute the above parameters into the following formula to calculate the driver's required power P DriverRequest Approximately equal to 31kW.

[0028] (2) Battery charge and discharge compensation power P ChargePower Determination of: Battery charge and discharge compensation power P ChargePower The driver's required power and SOCDiff (SOCDiff = current power - target power) are determined by looking up a two-dimensional table. The charge and discharge supplementary power filled in the table is determined through offline calculation and actual vehicle testing.

[0029] There are two purposes. One is to optimize the engine operating power and improve efficiency. As shown in Figure 3, when the driver's required power is relatively small or relatively large, that is, when the driver's required power is far from the current optimal engine operating power, for example, when it exceeds the preset range, if the driver's required power is directly executed, the engine's working efficiency will be significantly lower. Therefore, by adjusting the charge and discharge compensation power, the engine operating power is adjusted to the high-efficiency zone to achieve the purpose of improving engine efficiency. The other purpose is to maintain the balance of the high-voltage battery power. When SOCDiff is large, for example, when it exceeds the first power threshold, the current battery power is high, and the engine operating power can be adjusted to less than the driver's required power. The insufficient part is provided by the drive motor to the wheel by consuming the battery power. When SOCDiff is small, for example, when it is lower than the second power threshold (the second power threshold is lower than the first power threshold), the current battery power is low, and the engine operating power needs to be adjusted to greater than the driver's required power. The excess part is increased by the drive motor and the generator by generating electricity to increase the high-voltage battery power.

[0030] Assuming that the current power of the high-voltage battery is 45% and the target power is 60%, the SOCDiff is -15%. Assuming that the calibration data in the two-dimensional table is as shown in Table 1, according to the driver's required power P DriverRequest 31KW and SOCDiff is -15% Look up the table below to get the battery charge and discharge compensation power P ChargePower About -20kW.

[0031] Table 1 Battery charge and discharge compensation power lookup table

[0032] (3) Total engine power requirement P TotalEngine Equal to the driver's required power P DriverRequest and battery charge and discharge compensation power P ChargePower At this time, according to the above calculation results, P DriverRequest 31kW, P ChargePower = -20kW, substitute into the following formula to calculate the total engine required power P TotalEngine It is 51kW.

[0033] P TotalEngine =P DriverRequest -P ChargePower

[0034] The second step is to calculate the total engine power required P TotalEngine The final target engine speed nTargetEngineSpeed ​​is determined by other factors such as vehicle operating conditions, vehicle power system status, and environmental changes.

[0035] (1) Determination of the engine base target speed nBaseChargeSpeed:

[0036] Based on the total engine power requirement P TotalEngine The difference between the current power of the high-voltage battery and the target power SOCDiff is determined by looking up the two-dimensional table in nB aseChargeSpeed Given a given engine power requirement, a high-efficiency target engine speed is selected based on engine efficiency characteristics. The SOCDiff's impact on target speed selection is primarily reflected in the following: when SOCDiff is high, power generation demand is considered low, and a lower target engine speed can be selected to improve NVH performance. When SOCDiff is low, a higher target engine speed is selected, as higher speeds provide greater power generation capacity and improve battery charge. The target speeds calibrated in the table are determined through offline calculations and on-vehicle testing. Assuming the table calibration data shown in Table 2, the target engine speed selected based on a total engine power requirement of 51 kW and a SOCDiff of -15% is 3400 RPM.

[0037] Table 2 Engine basic target speed lookup table

[0038] (2) Determination of the minimum target engine speed nMinChargeSpeed:

[0039] The minimum target engine speed, nMinChargeSpeed, is determined by querying a two-dimensional table based on engine water temperature and atmospheric pressure. This is primarily intended to improve engine speed stability and torque responsiveness in harsh high-altitude and plateau environments by increasing engine speed. Assuming the calibrated two-dimensional table shown in Table 3, an atmospheric pressure of 100 kPa, and an engine water temperature of 90°C, the minimum target engine speed, nMinChargeSpeed, is 1000 RPM.

[0040] Table 3 Engine minimum target speed lookup table

[0041] (3) Determination of the maximum target engine speed nMaxChargeSpeed:

[0042] The maximum target engine speed, nMaxChargeSpeed, is determined based on a table lookup based on vehicle speed. This is primarily intended to improve vehicle NVH performance. At low speeds, engine noise from high rpm is more noticeable to the driver. The calibration principle for this setting is to limit the maximum engine speed at low speeds. Assuming the calibrated table shown in Table 4, at a vehicle speed of 40 km / h, the maximum target engine speed, nMaxChargeSpeed, is 3500 RPM.

[0043] Table 4 Engine maximum target speed lookup table

[0044] (4) Determination of the final target engine speed nTargetEngineSpeed:

[0045] The final target speed of the engine is determined by the basic target speed, the minimum target speed and the maximum target speed. The final target speed of the engine is selected based on factors such as the driver's required power (economy), the high-voltage battery power (SOC balance), the engine water temperature (engine operating conditions), the ambient atmospheric pressure (altitude), and the vehicle speed (NVH).

[0046] According to the above calculation results, the engine base target speed nBaseChargeSpeed ​​is 3400RPM, the engine minimum target speed nMinChargeSpeed ​​is 1000RPM, and the engine maximum target speed nMaxChargeSpeed ​​is 3500RPM. According to the following formula, the engine final target speed nTargetEngineSpeed ​​is 3400RPM.

[0047] nTargetEngineSpeed=MIN[MAX(nBaseChargeSpeed,nMinChargeSpeed),nMaxChargeSpeed]

[0048] The third step is to calculate the total engine power required P TotalEngine , the target engine speed, and the current engine speed nCrrentSpeed ​​are used to calculate the torque distribution between the engine, generator, and drive motor at this time. Assume that the current engine speed nCrrentSpeed ​​is 3200 RPM.

[0049] (1) Engine torque demand T Engine Calculation:

[0050] Engine torque demand T Engine Determined by the total engine power requirement and the actual engine speed. From the above calculation, we can see that at this time P TotalEngine The engine torque requirement T is calculated as follows: Engine About 152Nm.

[0051] (2) Generator torque requirement T GEN Calculation:

[0052] Generator torque requirement T GENIt consists of two parts. One part is the generator torque demand T that is balanced with the engine torque in the ECVT mode equilibrium state. GEN-Balance , the engine torque, the number of teeth of the outer ring gear of the planetary gear mechanism (z R ), number of sun gear teeth (z S ) is determined. Assume that the number of teeth on the outer ring gear of this project is z R is 63, the number of sun gear teeth is z S =30. From the above calculation, we know that the engine torque is 152Nm at this time. Then, the generator torque requirement T is calculated according to the following formula: GEN About -49Nm.

[0053] The other part is the engine speed control torque. The speed control module performs PID adjustment based on the engine target speed and actual speed, and calculates the speed control torque converted to the generator end as T GEN-SpeedControl At this time, the final target engine speed nTargetEngineSpeed ​​is 3400RPM, the current engine speed nCrrentSpeed ​​is 3300RPM, and the speed control torque T calculated by the idle speed control module is GEN-SpeedControl 5Nm.

[0054] At this time, the total generator torque required is T GEN The total generator torque requirement is calculated as:

[0055] T GEN =T GEN-Balance +T GEN-SpeedControl

[0056] (3) Drive motor required torque T Motor Calculation:

[0057] Drive motor required torque T Motor The calculation of the driver's wheel side torque T TorqueRequestOnWheel Determined by the difference between the engine torque demand and the portion of the torque applied to the wheels.

[0058] The portion of the engine torque demand that acts on the wheel side is T EngineOnWheel Calculation of the force T acting on the outer ring gear of the planetary gear mechanism by the engine RingGear and the speed ratio T from the outer ring gear to the wheel RingToWheel Based on the above assumed parameters and calculation results, substitute them into the following formula, then T RingGear About 103Nm. Assuming the speed ratio R from the outer ring gear to the wheel RingToWheel =7, then the engine torque demand acts on the wheel side part T EngineOnWheel About 721Nm.

[0059] T EngineOnWheel =T RingGear *R RingToWheel

[0060] Drive motor required torque T Motor The torque T required by the driver's wheel TorqueRequestOnWheel , the portion of the engine torque demand that acts on the wheel side T EngineOnWheel And the speed ratio R from the drive motor to the wheels MotorToWheel At this time, the driver's wheel side torque T TorqueRequestOnWheel The part of the engine torque demand that acts on the wheel side is 1000Nm. EngineOnWheel is 721Nm, assuming the speed ratio R from the drive motor to the wheel MotorToWheel is 10, then the drive motor requires torque T Motor It is 27.9Nm.

[0061] In ECVT mode, after the torque distribution of the engine, generator and drive motor is determined, the torque command is sent to the corresponding actuator for execution.

[0062] The present invention further provides a system for implementing the torque distribution method in the ECVT mode of the hybrid vehicle, comprising:

[0063] The engine power requirement module is used to determine the total engine power requirement based on the vehicle operating conditions and power system status;

[0064] The engine final target speed module is used to determine the engine final target speed based on the total engine power demand, the difference between the current power level of the high-voltage battery and the target power level, the engine water temperature, the atmospheric pressure and the vehicle speed;

[0065] The torque distribution module is used to determine the torque distribution of the engine, generator and drive motor based on the total engine required power, the engine's final target speed and the engine's actual speed.

[0066] The present invention also provides a hybrid vehicle, which adopts any one of the above-mentioned torque distribution methods in the ECVT mode of the hybrid vehicle type.

[0067] The present invention fully considers factors such as vehicle operating conditions, vehicle power system status and environmental changes, and designs a torque distribution method under ECVT mode. Different torque distribution is performed under different vehicle operating conditions, vehicle power system status and environmental factors, ensuring that the fuel economy and NVH performance of the vehicle are improved while the driver's needs are correctly implemented.

[0068] It should be noted that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0069] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, or two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0070] It will be easily understood by those skilled in the art that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A torque distribution method for a hybrid vehicle in the ECVT mode, which is used in the electronic equipment of the vehicle. The method is characterized in that: Determine the total engine required power according to the vehicle operating conditions and the power system state; Determine the final target engine speed according to the total engine required power, the difference between the current battery charge of the high-voltage battery and the target charge, the engine coolant temperature, the atmospheric pressure, and the vehicle speed; Determine the torque distribution of the engine, the generator, and the drive motor according to the total engine required power, the final target engine speed, and the actual engine speed.

2. The torque distribution method in the ECVT mode of the hybrid vehicle according to claim 1, wherein Determine the total engine required power according to the vehicle operating conditions and the power system state, including: Determine the driver required power; Determine the battery charge and discharge compensation power; The total engine required power is equal to the difference between the driver required power and the battery charge and discharge compensation power.

3. The torque distribution method in the ECVT mode of the hybrid vehicle according to claim 2, characterized in that, The driver's required power is determined by the driver's wheel-side required torque T TorqueRequestOnWheel , vehicle speed V vehicleSpeed , and tire radius R WheelRadius jointly: where P DriverRequest is the driver demand power.

4. The torque distribution method in the ECVT mode of the hybrid vehicle according to claim 2, wherein The battery charge and discharge compensation power is determined by looking up a two-dimensional table based on the driver required power and the difference SOCDiff between the current battery charge of the high-voltage battery and the target charge.

5. The torque distribution method in the ECVT mode of the hybrid vehicle according to claim 4, characterized in that, Wherein, When the difference between the driver required power and the optimal engine operating power is large, adjust the charge and discharge compensation power to adjust the engine operating power to the high-efficiency area to improve the engine efficiency; When SOCDiff is large, the current battery charge of the high-voltage battery is high. Adjust the engine operating power to be less than the driver required power, and the insufficient part is provided by the drive motor to provide driving force for the wheel hub by consuming the battery charge of the high-voltage battery. When SOCDiff is small, the current battery charge of the high-voltage battery is low. Adjust the engine operating power to be greater than the driver required power, and the excess part is used by the drive motor and the generator to generate electricity to increase the battery charge of the high-voltage battery.

6. The torque distribution method in the ECVT mode of the hybrid vehicle according to claim 1, characterized in that, Determine the final target engine speed according to the total engine required power, the difference between the current battery charge of the high-voltage battery and the target charge, the engine coolant temperature, the atmospheric pressure, and the vehicle speed, including: Determine the basic target engine speed nBaseChargeSpeed by looking up a two-dimensional table based on the total engine required power and the difference SOCDiff between the current battery charge of the high-voltage battery and the target charge. Under the determined total engine required power, select the engine target speed with high efficiency based on the engine efficiency characteristics. When SOCDiff is large, select a lower engine target speed. When SOCDiff is small, select a higher engine target speed; Determine the minimum target engine speed nMinChargeSpeed by looking up a two-dimensional table based on the engine coolant temperature and the atmospheric pressure; Determine the maximum target engine speed nMaxChargeSpeed by looking up a table based on the vehicle speed; Determine the final target engine speed according to the basic target engine speed, the minimum target engine speed, and the maximum target engine speed.

7. The torque distribution method in the ECVT mode of the hybrid vehicle according to claim 6, characterized in that Determine the final target engine speed according to the basic target engine speed, the minimum target engine speed, and the maximum target engine speed specifically as: nTargetEngineSpeed = MIN[MAX(nBaseChargeSpeed, nMinChargeSpeed), nMaxChargeSpeed] Wherein, nTargetEngineSpeed is the final target engine speed.

8. The torque distribution method in the ECVT mode of the hybrid vehicle according to claim 1, characterized in that Engine torque demand T Engine is calculated as follows: Where P TotalEngine is the total engine required power and nCurrentSpeed is the actual engine speed.

9. The torque distribution method in the ECVT mode of the hybrid vehicle according to claim 1, wherein Generator torque requirement T GEN is calculated as follows: According to the engine torque requirement T Engine , the number of teeth z of the ring gear of the planetary gear mechanism R , and the number of teeth z of the sun gear S Calculate the generator torque requirement T that balances the engine torque in the balanced state of the ECVT mode GEN-Balance : Calculate the rotational speed control torque T according to the final target rotational speed of the engine and the actual rotational speed of the engine through PID GEN-SpeedControl ; Calculate the generator torque requirement T GEN = T GEN-Balance + T GEN-SpeedControl .

10. The torque distribution method in the ECVT mode of the hybrid vehicle according to claim 1, characterized in that The required torque T of the drive motor Motor is calculated as follows: According to the force T exerted by the engine on the outer ring gear of the planetary gear mechanism RingGear and the speed ratio R from the outer ring gear to the wheel RingToWheel calculate the part T acting on the wheel side in the engine torque requirement EngineOnWheel : T EngineOnWheel = T RingGear * R RingToWheel According to the required torque \(T\) at the wheel side of the driver TorqueRequestOnWheel , the part \(T\) of the engine torque demand acting on the wheel side EngineOnWheel and the speed ratio \(R\) from the drive motor to the wheel MotorToWheel Calculate the required torque of the drive motor: where z R is the number of teeth of the ring gear of the planetary gear mechanism, z S is the number of teeth of the sun gear, and T Engine is the engine torque requirement.

11. A system for implementing the torque distribution method in the ECVT mode of the hybrid vehicle according to any one of claims 1-10, characterized in that, It includes: An engine demand power module, which is used to determine the total engine demand power according to the vehicle operating conditions and the power system state; An engine final target speed module, which is used to determine the engine final target speed according to the total engine demand power, the difference between the current power of the high-voltage battery and the target power, the engine water temperature, the atmospheric pressure, and the vehicle speed; A torque distribution module, which is used to determine the torque distribution of the engine, the generator, and the drive motor according to the total engine demand power, the engine final target speed, and the actual engine speed.

12. A hybrid vehicle, characterized in that, This hybrid vehicle adopts the torque distribution method in the ECVT mode of the hybrid vehicle type described in any one of claims 1 to 10.

Images