A control method for feedback torque of a hybrid system

Abstract

The application provides a control method of feedback torque of a hybrid power system, and is characterized by comprising the following steps: judging whether a condition for calculating a load coefficient is met, judging whether a whole vehicle is in a D gear, outputting a final load coefficient value, calculating a slope coefficient information after correction, outputting a feedback torque value according to a calibrated slope coefficient-feedback torque curve, and returning to step 1. The application effectively utilizes braking feedback energy of the whole vehicle, improves economy, reduces the frequency of braking by a driver, and reduces driving fatigue. The application does not depend on a slope sensor, and greatly saves matching costs.

Description

Technical Field

[0001] This invention relates to the field of hybrid vehicle technology, and in particular to a method for controlling the regenerative torque of a hybrid system. Background Technology

[0002] Faced with the increasingly severe energy crisis and environmental pollution, new energy vehicles have become the core direction of the automotive industry's development. Among them, hybrid electric vehicles (HEVs), as a key solution for the transition from traditional internal combustion engine vehicles to pure electric vehicles, effectively combine the advantages of both. Hybrid architectures possess pure electric drive capability, and their braking systems include both regenerative braking and mechanical braking modes. Under long downhill conditions, prioritizing regenerative braking using the electric motor not only improves vehicle economy through kinetic energy recovery but also significantly reduces the thermal load and overheating risk of the mechanical braking system. Therefore, optimizing the regenerative braking control strategy under this condition to achieve the best balance between economy and ride comfort has become an important research topic.

[0003] Currently, the industry mainly uses two types of regenerative braking methods for hybrid vehicles on long downhill slopes: coasting regenerative braking and brake regenerative braking. Coasting regenerative braking is mainly achieved by calibrating a fixed energy feedback torque or vehicle speed-feedback torque curve. If the feedback torque is too small, it cannot achieve a significant braking effect; if it is too large, it will affect driving comfort and cannot fully adapt to the constantly changing conditions of long downhill slopes. Braking regenerative braking is mainly achieved by calibrating a brake pedal opening-feedback torque curve. Using this method on long downhill slopes will cause the driver to frequently alternate between pressing the brake pedal and the driving pedal, increasing driver fatigue and also having a certain impact on the overall vehicle economy. Summary of the Invention

[0004] This invention provides a method for controlling the regenerative torque of a hybrid power system.

[0005] To achieve the above objectives, the present invention provides a method for controlling the feedback torque of a hybrid power system. The method calculates the current vehicle acceleration by reading the output shaft sensor of the hybrid powertrain, calculates the theoretical acceleration by the output shaft torque of the powertrain and the vehicle's driving assistance, and then calculates the approximate slope information. By calibrating the slope coefficient-feedback torque curve, the vehicle can travel at a suitable acceleration, thus achieving the "hill descent" function for long downhill slopes without the need for throttle and braking intervention.

[0006] A method for controlling the regenerative torque of a hybrid power system, characterized in that: S1: Determine whether the conditions for calculating the load factor are met. If yes, proceed to step S2; otherwise, proceed to step S3. Determine whether the load factor needs to be recalculated to improve control accuracy.

[0007] S2: Determine if the vehicle is in D gear. If yes, proceed to step S4; otherwise, proceed to step S3. S3: Using the original load factor value from the previous moment, proceed to step S5; S4: Calculate the load factor at the current moment, output the original value of the load factor at the current moment, and proceed to the next step; S5: Output the final load factor value and calculate the slope factor information after correction; S6: Determine whether the vehicle is in a gliding state. If so, output the feedback torque value according to the calibrated slope coefficient-feedback torque curve and return to step 1.

[0008] Preferably, the method for calculating the original value of the load factor in this invention is as follows: real-time reading of the current output shaft speed sensor value of the hybrid powertrain and calculation of the inertial acceleration α. 惯性 Based on the output shaft torque and vehicle running resistance, the wheel-side driving force after subtracting the running resistance is derived. The driving force acceleration α of the vehicle is then calculated using the wheel-side driving force. 驱动 ; Driving force acceleration α 驱动 With inertial acceleration α 惯性 The original value of the current load coefficient is calculated by subtraction. The gradient coefficient of this invention is calculated entirely from the vehicle's existing parameters, without relying on external gradient sensors, which greatly saves on supporting costs.

[0009] Preferably, the vehicle control unit (VCU) determines whether the vehicle is in braking mode, whether the hybrid powertrain oil temperature is lower than a set value, whether the hybrid powertrain output shaft speed is lower than a set value, whether the vehicle's ESC is activated, whether there is a sudden change in throttle opening, and whether the hybrid powertrain is in shifting mode. If at least one of the above conditions is met, the condition is not met; if none of the above conditions are met, the condition is met. This invention fully considers various situations and the impact of fluctuations in slope information calculation, resulting in more precise control.

[0010] Preferably, the method for calculating the slope coefficient information in step S5 of the present invention is as follows: ; In the formula, F 驱动 F is the total driving force of the vehicle. 惯性 Gsinθ is the inertial force of the vehicle, Gsinθ is the component of the vehicle's weight on the slope, and F is the inertial force. 阻力 The vehicle's resistance to movement, g is the acceleration due to gravity, m is the total mass of the vehicle, and α is the resistance to movement. 驱动 For the vehicle's driving force acceleration, α 惯性 Let θ be the inertial acceleration of the vehicle, and θ be the angle of the slope.

[0011] The above formula provides the slope coefficient information, namely the slope angle θ and the vehicle mass m, which are used as control variables for feedback torque control. The calculation is based on the following: When a vehicle is traveling uphill or downhill, force analysis using a non-inertial reference frame shows that the total driving force output by the powertrain is equal to the sum of the vehicle's resistance to movement, the component of gravity on the slope, and the inertial force. That is:

[0012] Further:

[0013] When the slope is small, sinθ can be approximated as tanθ on a small slope, and tanθ can be approximated as θ on a small slope. The slope can be approximated as the sine of the slope. Based on the above information, the slope coefficient of the road where the vehicle is located can be approximately calculated, that is, the slope angle θ and the vehicle mass m, as shown in the following formula:

[0014] Based on the actual vehicle test of the gradient coefficient, the gradient coefficient-feedback torque curve can be calibrated. When the vehicle is in a long downhill coasting feedback state, the vehicle controller outputs feedback torque that matches the currently calculated gradient according to the gradient coefficient-feedback torque curve, so that the driver can get appropriate downhill acceleration without frequently pressing the brake pedal and accelerator pedal.

[0015] In the formula, F 驱动 The total driving force of the vehicle is calculated and derived in this invention using information such as output shaft torque, rear axle ratio, tire radius, and gearbox transmission efficiency. F 惯性 The inertial force of the vehicle can be derived by differentiating the vehicle speed or the output shaft speed.

[0016] Gsinθ is the component of the vehicle's weight on the slope, F 阻力 The driving resistance of a vehicle can be measured through a vehicle coasting test.

[0017] m is the total vehicle mass, α 驱动 For the vehicle's driving force acceleration, α 惯性 Let θ be the inertial acceleration of the vehicle, and θ be the angle of the slope.

[0018] Preferably, the slope coefficient information calculation method is used when the vehicle is fully loaded. That is, the slope coefficient information calculation method of the present invention is for fully loaded conditions. When lightly loaded, the load coefficient value needs to be corrected. In the calculation method of the present invention, θ is related to the vehicle mass. The mass is set according to the fully loaded state of the vehicle. For a heavy vehicle traveling on a certain slope, the above calculation algorithm can calculate that the load coefficient is consistent with the slope. Since the mass of commercial vehicles can vary greatly, if the mass of the vehicle becomes very small, the calculated slope will be different from that of a fully loaded vehicle. Therefore, the slope coefficient information calculation method takes into account the mass of the vehicle, that is, it includes the slope angle θ and the mass m of the vehicle.

[0019] Preferably, in step S6 of the present invention, the slope coefficient-feedback torque curve is obtained through testing and calibration. This results in low cost and precise control.

[0020] Specifically, in step S6 of the present invention, the vehicle controller (VCU) outputs a feedback torque that matches the currently calculated slope based on the slope coefficient-feedback torque curve, and transmits the torque to the drive motor controller, so that the drive motor outputs braking torque.

[0021] Compared with the prior art, the present invention has the following beneficial effects: It offers good economic efficiency, reduces driver braking frequency, and boasts a high degree of automation, thus reducing driver fatigue. Unlike existing coasting and braking feedback methods in the industry that use fixed energy feedback torque or vehicle speed (brake pedal opening) - feedback torque curves, the control method provided by this invention, which automatically adjusts the feedback torque during downhill driving based on the load coefficient, tests and calibrates an appropriate gradient coefficient - feedback torque curve. This allows the vehicle to output suitable feedback torque under long downhill conditions, achieving a "hill descent control" function. It effectively utilizes the vehicle's braking feedback energy, improves economic efficiency, and reduces the frequency of driver braking, thereby reducing driving fatigue.

[0022] The slope coefficient parameters of this invention are derived entirely by an algorithm, without relying on slope sensors, which greatly saves on supporting costs. Attached Figure Description

[0023] Figure 1 This is a control flowchart of a control method for controlling the regenerative torque of a hybrid power system according to the present invention.

[0024] Figure 2 This is the control logic diagram of the present invention.

[0025] Figure 3 This is a force analysis diagram of the vehicle of the present invention on a slope. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0027] In the description of this invention, it should be understood that the terms "left", "right", "up", "down", "front", "back", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or structure referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. Example

[0028] like Figure 1 and Figure 2 As shown, a method for controlling the regenerative torque of a hybrid power system includes the following steps: S1: Determine whether the conditions for calculating the load factor are met. If yes, proceed to step S2; otherwise, proceed to step S3. S2: Determine if the vehicle is in D gear. If yes, proceed to step S4; otherwise, proceed to step S3. S3: Using the original load factor value from the previous moment, proceed to step S5; S4: Calculate the load factor at the current moment, output the original value of the load factor at the current moment, and proceed to the next step; S5: Output the final load factor value and calculate the slope factor information after correction; S6: Determine whether the vehicle is in a gliding state. If so, output the feedback torque value according to the calibrated slope coefficient-feedback torque curve and return to step 1.

[0029] This embodiment calculates approximate slope information and calibrates the slope coefficient-feedback torque curve to enable the vehicle to travel at a suitable acceleration, thus achieving the "hill descent" function for long downhill slopes without the need for throttle and brake intervention. Example

[0030] like Figure 1 and Figure 2 As shown, a method for controlling the regenerative torque of a hybrid power system includes the following steps: S1: Determine whether the conditions for calculating the load factor are met. If yes, proceed to step S2; otherwise, proceed to step S3. Determine whether the load factor needs to be recalculated to improve control accuracy.

[0031] S2: Determine if the vehicle is in D gear. If yes, proceed to step S4; otherwise, proceed to step S3. S3: Using the original load factor value from the previous moment, proceed to step S5; S4: Calculate the load factor at the current moment, output the original value of the load factor at the current moment, and proceed to the next step; S5: Output the final load factor value, which is the original load factor value output in step 4 or step 3, and the slope factor information is calculated after correction. S6: Determine if the vehicle is in a gliding state. If so, output the feedback torque value according to the calibrated slope coefficient-feedback torque curve, return to step 1, and end.

[0032] In this embodiment, the method for calculating the original value of the load factor is as follows: real-time reading of the current hybrid powertrain output shaft speed sensor value and calculation of the inertial acceleration α. 惯性 Based on the output shaft torque and vehicle running resistance, the wheel-side driving force after subtracting the running resistance is derived. The driving force acceleration α of the vehicle is then calculated using the wheel-side driving force. 驱动 ; Driving force acceleration α 驱动 With inertial acceleration α 惯性 The original value of the current load coefficient is calculated by subtraction. The gradient coefficient of this invention is calculated entirely from the vehicle's existing parameters, without relying on external gradient sensors, which greatly saves on supporting costs.

[0033] In this embodiment, the vehicle control unit (VCU) determines whether the vehicle is in braking mode, whether the hybrid powertrain oil temperature is lower than a set value, whether the hybrid powertrain output shaft speed is lower than a set value, whether the vehicle's ESC is activated, whether there is a sudden change in throttle opening, and whether the hybrid powertrain is shifting gears. If at least one of these conditions is met, the condition is not met; if none of the above conditions are met, the condition is met. This invention fully considers various situations and the impact of fluctuations in slope information calculation, resulting in more precise control.

[0034] In this embodiment, the method for calculating the slope coefficient information in step S5 is as follows:

[0035] In the formula, F 驱动 F is the total driving force of the vehicle. 惯性 Gsinθ is the inertial force of the vehicle, Gsinθ is the component of the vehicle's weight on the slope, and F is the inertial force. 阻力 The vehicle's resistance to movement, where m is the total vehicle mass, and α is the resistance to movement. 驱动 For the vehicle's driving force acceleration, α 惯性 Let θ be the inertial acceleration of the vehicle, and θ be the angle of the slope.

[0036] In the formula, α 驱动 -α 惯性 That is, the final load factor. Substituting the final load factor into the above formula, the slope angle θ can be calculated.

[0037] The above formula provides information on the slope coefficient, namely the slope angle θ and the vehicle mass m, which are used as control variables for feedback torque control.

[0038] like Figure 3 As shown, the calculation is based on the following: When the vehicle is traveling uphill or downhill, force analysis using a non-inertial reference frame shows that when the vehicle is traveling on a slope, the total driving force output by the powertrain is equal to the sum of the vehicle's driving resistance, the component of gravity on the slope, and the inertial force, that is:

[0039] Further:

[0040] When the slope is small, sinθ can be approximated as tanθ on a small slope, and tanθ can be approximated as θ on a small slope. The slope can be approximated as the sine of the slope. Based on the above information, the slope coefficient of the road where the vehicle is located can be approximately calculated, that is, the slope angle θ and the vehicle mass m, as shown in the following formula:

[0041] Based on the actual vehicle test of the gradient coefficient, the gradient coefficient-feedback torque curve can be calibrated. When the vehicle is in a long downhill coasting feedback state, the vehicle controller outputs feedback torque that matches the currently calculated gradient according to the gradient coefficient-feedback torque curve, so that the driver can get appropriate downhill acceleration without frequently pressing the brake pedal and accelerator pedal.

[0042] In the formula, F 驱动 The total driving force of the vehicle is calculated and derived in this invention using information such as output shaft torque, rear axle ratio, tire radius, and gearbox transmission efficiency. F 惯性 The inertial force of the vehicle can be derived by differentiating the vehicle speed or the output shaft speed.

[0043] Gsinθ is the component of the vehicle's weight on the slope, F 阻力 The driving resistance of a vehicle can be measured through a vehicle coasting test.

[0044] m is the total vehicle mass, α 驱动 For the vehicle's driving force acceleration, α 惯性 Let θ be the inertial acceleration of the vehicle, and θ be the angle of the slope.

[0045] In the calculation method of this embodiment, θ is related to the vehicle mass. The mass is set according to the full load state of the vehicle. When a heavy vehicle travels on a certain slope, the above calculation method algorithm can calculate that the load coefficient is consistent with the slope. Since the mass of commercial vehicles can vary greatly, if the mass of the vehicle becomes very small, the calculated slope will be different from that of a fully loaded vehicle. Therefore, the slope coefficient information calculation method takes into account the mass of the vehicle, that is, it includes the slope angle θ and the mass m of the vehicle.

[0046] In step S6 of this embodiment, the slope coefficient-feedback torque curve is obtained through testing and calibration. By querying the slope angle θ and vehicle mass m information in the curve, the feedback torque can be determined. This method is low-cost and provides precise control.

[0047] In step S6 of this embodiment, the vehicle controller (VCU) outputs a feedback torque that matches the currently calculated slope based on the slope coefficient-feedback torque curve, and transmits the torque to the drive motor controller, so that the drive motor outputs braking torque.

[0048] This embodiment calculates the vehicle's driving force acceleration α using the output shaft sensor readings of the hybrid powertrain. 驱动 The inertial acceleration α is calculated by using the powertrain output shaft torque and the vehicle's driving assistance. 惯性 This allows for the calculation of approximate slope information. By calibrating the slope coefficient-feedback torque curve, the vehicle can travel at a suitable acceleration, achieving the "hill descent" function for long downhill slopes without the need for throttle and brake intervention.

Claims

1. A method for controlling the regenerative torque of a hybrid power system, characterized in that: S1: Determine whether the conditions for calculating the load factor are met. If yes, proceed to step S2; otherwise, proceed to step S3. S2: Determine if the vehicle is in D gear. If yes, proceed to step S4; otherwise, proceed to step S3. S3: Using the original load factor value from the previous moment, proceed to step S5; S4: Calculate the load factor at the current moment, output the original value of the load factor at the current moment, and proceed to the next step; S5: Output the final load factor value and calculate the slope factor information after correction; S6: Determine whether it is in a gliding state. If so, output the feedback torque value according to the calibrated slope coefficient-feedback torque curve and return to step 1. The method for calculating the original value of the load factor is as follows: read the value of the current hybrid powertrain output shaft speed sensor in real time and calculate the inertial acceleration α. 惯性 ; Based on the output shaft torque and vehicle running resistance, the wheel-side driving force after subtracting the running resistance is derived. The driving force acceleration α of the vehicle is then calculated from the wheel-side driving force. 驱动 ; Driving force acceleration α 驱动 With inertial acceleration α 惯性 The difference is used to calculate the original value of the current load factor; The conditions for determining whether the load factor is met include: the vehicle controller (VCU) determines that the vehicle is in a braking state, the hybrid powertrain oil temperature is lower than the set value, the hybrid powertrain output shaft speed is lower than the set value, the vehicle's ESC is activated, there is a sudden change in throttle opening, and the hybrid powertrain is in a shifting state. If at least one of the above conditions is met, the condition is not met; if none of the above conditions are met, the condition is met.

2. The method for controlling the regenerative torque of a hybrid power system according to claim 1, characterized in that... The method for calculating the slope coefficient information in step S5 is as follows: ； In the formula, F 驱动 F is the total driving force of the vehicle. 惯性 Gsinθ is the inertial force of the vehicle, Gsinθ is the component of the vehicle's weight on the slope, and F is the inertial force. 阻力 Let g be the vehicle's resistance, m be the acceleration due to gravity, and α be the total mass of the vehicle. 驱动 For the vehicle's driving force acceleration, α 惯性 Let θ be the inertial acceleration of the vehicle, and θ be the angle of the slope.

3. The method for controlling the regenerative torque of a hybrid power system according to claim 2, characterized in that: In S6, the slope coefficient-feedback torque curve is obtained through testing and calibration.

4. The method for controlling the regenerative torque of a hybrid power system according to claim 2, characterized in that: In S6, the vehicle controller outputs a feedback torque that matches the currently calculated slope based on the slope coefficient-feedback torque curve, and transmits this torque to the drive motor controller, which then outputs braking torque from the drive motor.

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