Calibration method for coasting regenerative braking conditions of vehicle and computer program product

Abstract

The invention relates to a calibration method for a sliding regenerative braking working condition of a vehicle. The calibration method comprises the steps that a target deceleration curve of the vehicle under the sliding regenerative braking working condition is obtained; acquiring an initial filter coefficient of the regenerative torque of the motor, and realizing a target deceleration curve only by combining the regenerative torque of the motor with the initial filter coefficient under the condition of no hydraulic braking torque; the regeneration torque of the motor is set to be 0, and the braking process of the vehicle is implemented only through the hydraulic braking torque; and S3, the initial filter coefficient is set as initial calibration of a first filter coefficient of the hydraulic braking torque, the first filter coefficient is adjusted from the initial calibration until the deviation of the deceleration curve of the braking process in the step S3 relative to the target deceleration curve is smaller than a preset threshold value, and a calibration result of the first filter coefficient is obtained. The invention also relates to a computer program product. The efficiency and the accuracy of the calibration test are improved, the smoothness and the consistency of deceleration and parking of the vehicle under different working conditions are ensured, and the driving experience feeling of a user is improved.

Description

Technical Field

[0001] The present invention relates to the field of vehicle technology, and in particular to a calibration method for a coasting regenerative braking condition of a vehicle. The present invention also relates to a corresponding computer program product. Background Art

[0002] In electric vehicles or hybrid vehicles, the coasting deceleration and parking process of the vehicle is controlled by combining brake caliper hydraulic braking and motor regenerative braking. The motor regenerative braking can convert part of the vehicle's kinetic energy into electrical energy for storage to improve endurance. Here, the motor regenerative braking is first used for deceleration, and as the vehicle speed decreases, hydraulic braking is used for compensation, and the motor regenerative braking is gradually withdrawn during the parking phase, so that the main parking brake function is assumed by the hydraulic braking. Here, it is necessary to calibrate the control parameters of the motor regenerative torque and the hydraulic braking torque so that the vehicle can smoothly decelerate and stop under different conditions. However, the calibration test in the prior art takes a lot of time and cannot ensure the smoothness of the vehicle during the coasting deceleration and parking process. Summary of the invention

[0003] Therefore, the purpose of the present invention is to propose an improved calibration method for a vehicle's coasting regenerative braking condition, which can significantly improve the efficiency and accuracy of the calibration test, ensure the smoothness and consistency of the vehicle's deceleration and parking under different conditions, and thus improve the user's driving experience. The purpose of the present invention is also to propose a corresponding computer program product.

[0004] According to a first aspect of the present invention, a calibration method for a coasting regenerative braking condition of a vehicle is provided, wherein the calibration method comprises at least the following steps:

[0005] S1: obtaining a target deceleration curve of the vehicle under the coasting regenerative braking condition;

[0006] S2: acquiring an initial filter coefficient of the motor regeneration torque, wherein the target deceleration curve is realized only by the motor regeneration torque combined with the initial filter coefficient in the absence of hydraulic braking torque;

[0007] S3: setting the motor regenerative torque to 0, and implementing the braking process of the vehicle only by hydraulic braking torque;

[0008] S4: The initial filter coefficient is set as the initial calibration of the first filter coefficient of the hydraulic braking torque, and the first filter coefficient is adjusted based on the initial calibration until the deviation of the deceleration curve of the braking process in step S3 relative to the target deceleration curve is less than a preset threshold, thereby obtaining the calibration result of the first filter coefficient.

[0009] Compared with the prior art, in the calibration method according to the present invention, by obtaining the initial filter coefficient of the motor regenerative torque and the first filter coefficient of the hydraulic brake torque according to the target deceleration curve, even if the hydraulic brake torque and the motor regenerative torque are simultaneously involved in the braking process, the deceleration curve of the vehicle can still be basically consistent with the target deceleration curve, regardless of the specific values ​​of the hydraulic brake torque and the motor regenerative torque and the driving conditions, which can ensure the smoothness and consistency of the vehicle's deceleration and parking under different conditions. In addition, the initial filter coefficient of the motor regenerative torque is set as the initial calibration of the first filter coefficient of the hydraulic brake torque, and the first filter coefficient is adjusted based on the initial calibration, which can greatly reduce the number and complexity of calibration tests, thereby significantly improving the efficiency and accuracy of calibration tests.

[0010] Exemplarily, in the coasting regenerative braking condition, when the speed of the vehicle is greater than a speed threshold, the vehicle is in a coasting deceleration phase, and when the speed of the vehicle is less than or equal to the speed threshold, the vehicle is in a coasting parking phase.

[0011] Exemplarily, the calibration method includes step S5: in the coasting stop stage, on roads with different slopes, the motor regenerative torque is set to 0 and the hydraulic braking torque is adjusted until a minimum hydraulic braking torque is determined that allows the vehicle to stop on the road without slipping, the product of the minimum hydraulic braking torque and a first safety factor is used as a calibration result of the hydraulic braking target torque, and the first filter coefficient is adjusted according to the hydraulic braking target torque.

[0012] Exemplarily, each slope and the corresponding hydraulic braking target torque are recorded in a hydraulic braking target torque mapping table, wherein the corresponding hydraulic braking target torque is calculated for the unrecorded slope by interpolation; and / or, the hydraulic braking target torque corresponding to a slope of 0 is set to the product of the hydraulic braking target torque corresponding to a preset slope range and a second safety factor; and / or, the hydraulic braking target torque corresponding to a negative slope is set to the product of the hydraulic braking target torque corresponding to the absolute value of the slope and a third safety factor.

[0013] Exemplarily, the calibration method includes step S6: in the coasting deceleration stage, setting the initial filter coefficient to the calibration result of the second filter coefficient of the motor regenerative torque; in the coasting stop stage, when the slope of the road surface on which the vehicle is located is equal to 0, setting the initial filter coefficient to the calibration result of the second filter coefficient of the motor regenerative torque; in the coasting stop stage, when the slope of the road surface on which the vehicle is located is not equal to 0, additionally setting the motor braking target torque on the basis of the hydraulic braking target torque and adjusting the initial filter coefficient of the motor regenerative torque according to the motor braking target torque as the calibration result of the second filter coefficient.

[0014] Exemplarily, in the coasting stop phase, the target deceleration curve and the initial filter coefficient are acquired through experiments on a road surface with a slope of zero.

[0015] Exemplarily, the filter coefficients of the motor regeneration torque and the hydraulic brake torque include at least a first-order filter coefficient and a gradient filter coefficient and are used to adjust the rising rate of the corresponding torque.

[0016] Exemplarily, in the coasting regenerative braking condition, the required braking torque is calculated according to the speed and deceleration of the vehicle, and the required braking torque is allocated to the motor regenerative torque and the hydraulic braking torque based on test data and / or an empirical formula.

[0017] Exemplarily, during the driving of the vehicle, when the accelerator pedal opening of the vehicle is less than an accelerator pedal opening threshold and the brake pedal opening of the vehicle is less than a brake pedal opening threshold, it is determined that the vehicle is in the gliding regenerative braking condition; and / or, the calibration method is used for the single-pedal mode of the vehicle.

[0018] According to a second aspect of the present invention, a computer program product is provided, comprising a computer program, wherein when the computer program is executed by one or more processors, the processors are capable of performing the calibration method according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be described in more detail below with reference to the accompanying drawings, so that the principles, features and advantages of the present invention can be better understood. The accompanying drawings include:

[0020] Figure 1 A schematic graph showing motor regenerative torque and hydraulic brake torque in a coasting regenerative braking condition of a vehicle according to an exemplary embodiment of the present invention;

[0021] Figure 2 A schematic flow chart of a calibration method for a coasting regenerative braking condition of a vehicle according to an exemplary embodiment of the present invention is shown;

[0022] Figure 3 A schematic diagram showing a speed curve of a coasting regenerative braking condition according to an exemplary embodiment of the present invention;

[0023] Figure 4 A schematic view is shown of a coasting stop phase of a vehicle on a road with a slope according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial technical effects to be solved by the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and multiple exemplary embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the scope of protection of the present invention.

[0025] This specification provides method operation steps as described in the embodiments or flow charts, but more or fewer operation steps may be included based on routine or non-creative work. The order of steps listed in the embodiments is only one way of executing the steps among many, and does not represent the only execution order.

[0026] It should be understood that, in this document, the expressions "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance, nor should they be understood as implicitly indicating the number of technical features indicated. Features defined as "first" or "second" may explicitly or implicitly indicate that at least one of the features is included.

[0027] Figure 1 : shows the motor regenerative torque T of the vehicle 10 in a coasting regenerative braking condition according to an exemplary embodiment of the present invention. M and hydraulic brake torque T H Here, the vehicle 10 may be an electric vehicle or a hybrid vehicle. In particular, the coasting regenerative braking condition is implemented in the single-pedal mode of the vehicle 10. In the single-pedal mode, when the driver releases the accelerator pedal, the vehicle 10 implements the regenerative braking function by reversing the motor, converting kinetic energy into electrical energy and generating braking force to decelerate the vehicle 10. Of course, it is also possible to implement the coasting regenerative braking condition by stepping on the brake pedal.

[0028] like Figure 1 As shown, the driver releases the accelerator pedal at time t=0, the vehicle 10 enters the coasting regenerative braking state and the speed v of the vehicle 10 decreases accordingly. When the coasting regenerative braking starts, the motor regenerative torque T M It takes on the main braking function and is significantly greater than the hydraulic braking torque T H, so that the motor energy feedback is used first to realize the deceleration and sliding of the vehicle 10. As the speed v of the vehicle 10 decreases, the motor regenerative torque T M The hydraulic braking torque T H As the compensation torque intervenes and gradually increases, the total braking torque satisfies the braking demand torque. Finally, when the vehicle 10 approaches a stop or when the time t reaches the stop time t0, the motor regenerative torque T M Basically exit and through the hydraulic interaction torque T H Here, in particular in the single-pedal mode of the vehicle 10, when the accelerator pedal opening of the vehicle 10 is less than a preset accelerator pedal opening threshold and the brake pedal opening of the vehicle 10 is less than a preset brake pedal opening threshold, it is determined that the vehicle 10 is in the coasting regenerative braking state.

[0029] For example, in the coasting regenerative braking condition, the required braking torque is calculated according to the speed v and deceleration of the vehicle 10, and the required braking torque is allocated to the motor regenerative torque T based on test data and / or empirical formulas. M and hydraulic brake torque T H , where the motor regenerative torque T M and hydraulic brake torque T H The share in the required braking torque can be determined based on parameters such as speed v, braking intensity and energy recovery strategy.

[0030] Figure 2 A schematic flow chart of a calibration method for a coasting regenerative braking condition of a vehicle 10 according to an exemplary embodiment of the present invention is shown.

[0031] like Figure 2 As shown, the calibration method for the coasting regenerative braking condition of the vehicle 10 according to the present invention comprises at least the following steps:

[0032] S1: obtaining a target deceleration curve of the vehicle 10 under a coasting regenerative braking condition, wherein the target deceleration curve indicates an expected rate at which the speed v of the vehicle 10 decreases over time, so as to achieve a smooth deceleration and parking process and meet safety and comfort requirements of the vehicle 10, wherein the target deceleration curve may be obtained in particular based on empirical data, simulation data, and actual test data;

[0033] S2: Get the motor regenerative torque T M The initial filter coefficient is, where, in the absence of hydraulic brake torque T H In this case, the brake caliper does not participate in the braking process, and only the motor regenerative torque T M Combined with the initial filter coefficient, the target deceleration curve in step S1 is realized. The motor regenerative torque T can be obtained by the initial filter coefficient.M Output smoothing and reducing motor regenerative torque T M fluctuations and instantaneous impacts, thereby improving the driving comfort and stability of the vehicle 10 when braking by the motor;

[0034] S3: The motor regenerative torque T M Set to 0, that is, the motor does not participate in the braking process, and only the hydraulic braking torque T of the brake caliper is used. H Implementing a braking process of the vehicle 10;

[0035] S4: The motor regenerative torque T obtained in step S2 is M The initial filter coefficient is set to the hydraulic brake torque T H The hydraulic brake torque T is adjusted based on the initial calibration of the first filter coefficient. H The first filter coefficient of , until the hydraulic brake torque T is used only in step S3 H The deviation of the deceleration curve of the implemented braking process relative to the target deceleration curve in step S1 is less than a preset threshold value, and a calibration result of the first filter coefficient is obtained. The first filter coefficient can be used to make the hydraulic brake torque T H Output smooth and reduce hydraulic brake torque T H The fluctuation and instantaneous impact of the hydraulic brake torque T can be reliably ensured to improve the driving comfort and stability of the vehicle 10 when the vehicle 10 is braked by the brake caliper, wherein the preset threshold value can be determined according to empirical data, for example, 10%. H The deceleration curve during the braking process is basically consistent with the target deceleration curve.

[0036] Therefore, based on the calibrated motor regenerative torque T M The initial filter coefficient and hydraulic brake torque T H The first filter coefficient of , the motor and the brake caliper can respectively implement the braking process that conforms to the target deceleration curve. In this case, in the coasting regenerative braking condition, even if the hydraulic brake torque T H and motor regenerative torque T M At the same time, the intervention in the braking process can still make the deceleration curve of the vehicle 10 basically consistent with the target deceleration curve, which can ensure the smoothness of the vehicle's deceleration and parking under different working conditions.

[0037] For example, the motor regenerative torque T M and hydraulic brake torque T HThe filter coefficients at least include a first-order filter coefficient and a gradient filter coefficient. Of course, other filter coefficient forms that are considered meaningful by those skilled in the art may also be considered, such as second-order or higher-order filter coefficients, Kalman filter coefficients, etc. Here, the filter coefficients are used to adjust the rising rate of the corresponding torque to make the change of the torque smoother.

[0038] Figure 3 A schematic diagram of a speed curve of a coasting regenerative braking condition according to an exemplary embodiment of the present invention is shown.

[0039] like Figure 3 As shown, the driver releases the accelerator pedal at time t=0, the vehicle 10 enters the coasting regenerative braking state, and the vehicle 10 is completely parked when time t reaches the parking time t0. H and motor regenerative torque T M The braking effect of the vehicle 10 gradually decreases from time t0 to t0. Here, the coasting regenerative braking condition is divided into different stages according to the speed v of the vehicle 10, wherein when the speed v is greater than the speed threshold v0, the vehicle 10 is in the coasting deceleration stage H1, in which the motor regenerative torque T M can play a major role, and when the speed v is less than or equal to the speed threshold v0, the vehicle 10 is in the coasting parking stage H2, in which the hydraulic braking torque T H The speed v of the vehicle 10 gradually decreases to 0 and finally stops. Here, the coasting parking phase H2 is performed immediately after the coasting deceleration phase H1. In particular, the hydraulic braking torque T H The first filter coefficient in the coasting deceleration phase H1 and the coasting stop phase H2 can be adaptively changed.

[0040] For example, in the coasting stop phase H2, the target deceleration curve in step S1 and the initial filter coefficient in step S2 are obtained by testing on a road surface with a slope θ of 0. This allows the test results of the target deceleration curve and the initial filter coefficient to be standardized and widely applied to different working conditions.

[0041] Figure 4 A schematic diagram showing a coasting stop phase H2 of a vehicle 10 on a road surface having a slope θ according to an exemplary embodiment of the present invention is shown.

[0042] like Figure 4 As shown, in the coasting parking phase, the vehicle 10 is located on a road surface with a slope θ, in particular parked on the road surface. Here, the slope θ can be a positive value, that is, the vehicle 10 is located on an uphill slope. It is also possible that the slope θ can be 0, that is, the vehicle 10 is located on a flat road, or a negative value, that is, the vehicle 10 is located on a downhill slope.

[0043] like Figure 1 and Figure 2 As shown, the calibration method according to the present invention comprises step S5: in the coasting stop stage H2, on the road surface with different slopes θ, the motor regenerative torque T M Set to 0 and adjust the hydraulic brake torque T H , until the minimum hydraulic braking torque that allows the vehicle 10 to stop on the road without slipping is determined, and the product of the minimum hydraulic braking torque and the first safety factor is used as the hydraulic braking target torque T HZ The calibration result is calculated based on the hydraulic brake target torque T HZ The first filter coefficient is adjusted so that the first filter coefficient can be optimized while avoiding the vehicle from rolling. For example, when ensuring that the vehicle 10 does not roll, if the deceleration of the vehicle 10 is too small, the first filter coefficient is adjusted to increase the hydraulic braking torque T H Here, the hydraulic braking target torque T HZ The vehicle 10 can be stably parked on the road surface, wherein the parking safety of the vehicle 10 can be improved by a first safety factor, which can be obtained from test data and / or empirical data, for example, 1.2.

[0044] For example, after multiple calibration tests, each slope θ and the corresponding hydraulic brake target torque T HZ The hydraulic brake target torque mapping table records the hydraulic brake target torque T corresponding to the specific slope θ, and the control unit of the vehicle can easily retrieve the hydraulic brake target torque T corresponding to the specific slope θ from the hydraulic brake target torque mapping table. HZ Here, the slope θ for the calibration test can be dispersed, for example, 10°, 15°, 20°, 30°, etc., wherein the corresponding hydraulic brake target torque T is calculated by interpolation method for the slope θ that has not been tested or recorded. HZ For example, the hydraulic brake target torque at a slope θ of 25° is equal to the average of the hydraulic brake target torques at a slope θ of 20° and a slope θ of 30°. In particular, the hydraulic brake target torque corresponding to a slope θ of 0 is set to the product of the hydraulic brake target torque corresponding to a preset slope range, such as 2° to 3°, and a second safety factor, which may be 0.7, for example. This ensures that the vehicle 10 is stably parked on a flat road.

[0045] Exemplarily, the hydraulic brake target torque corresponding to a negative slope θ is set to the product of the hydraulic brake target torque corresponding to the absolute value of the slope θ and the third safety factor, and the third safety factor is, for example, 0.9. For example, the hydraulic brake target torque for a slope θ of -10° is the product of the hydraulic brake target torque for a slope θ of 10° and 0.9. This can greatly save calibration steps and improve calibration efficiency.

[0046] For example, Figure 1 and Figure 2 As shown, the calibration method according to the present invention further includes step S6, in which the motor regenerative torque T in the coasting regenerative braking condition is calculated. M In the coasting deceleration stage H1, the initial filter coefficient obtained in step S2 is set to the motor regeneration torque T M In the coasting stop stage H2, when the slope θ of the road on which the vehicle 10 is located is equal to 0, the initial filter coefficient is also set to the motor regeneration torque T M In addition, in the coasting parking stage H2, when the slope θ of the road on which the vehicle is located is not equal to 0, the hydraulic braking target torque T HZ The motor braking target torque T is additionally set on the basis of MZ The motor braking target torque can ensure that the vehicle does not slip, and according to the motor braking target torque T MZ Adjust the motor regenerative torque T M The initial filter coefficient is used as the motor regenerative torque T M The calibration result of the second filter coefficient.

[0047] According to the present invention, a computer program product is also proposed, which comprises a computer program. When the computer program is executed by one or more processors, the processors are capable of executing the calibration method according to the present invention.

[0048] The above explanation of the embodiments only describes the invention within the framework of the examples. Of course, the individual features of the embodiments can be freely combined with one another as long as it makes technical sense, without departing from the framework of the invention.

[0049] Other advantages and alternative embodiments of the present invention are obvious to those skilled in the art. Therefore, the present invention in its broader sense is not limited to the specific details, representative structures and exemplary embodiments shown and described. On the contrary, those skilled in the art can make various modifications and substitutions without departing from the basic spirit and scope of the present invention.

Claims

1. A calibration method for a coasting regenerative braking condition of a vehicle (10), characterized in that: The calibration method comprises at least the following steps: S1: obtaining a target deceleration curve of the vehicle (10) under the coasting regenerative braking condition; S2: Get the motor regenerative torque (T M ) is the initial filter coefficient, where, in the absence of hydraulic braking torque (T H ) is the case where only the motor regenerative torque (T M ) realizing the target deceleration curve in combination with the initial filter coefficient; S3: The motor regenerative torque (T M ) is set to 0, only the hydraulic braking torque (T H ) implementing a braking process of the vehicle (10); S4: Set the initial filter coefficient to the hydraulic brake torque (T H ) is initially calibrated, and the first filter coefficient is adjusted based on the initial calibration until the deviation of the deceleration curve of the braking process in step S3 relative to the target deceleration curve is less than a preset threshold, thereby obtaining a calibration result of the first filter coefficient.

2. The calibration method according to claim 1, characterized in that: Under the coasting regenerative braking condition, when the speed (v) of the vehicle (10) is greater than a speed threshold (v0), the vehicle (10) is in a coasting deceleration stage (H1), and when the speed (v) of the vehicle (10) is less than or equal to the speed threshold (v0), the vehicle (10) is in a coasting parking stage (H2).

3. The calibration method according to claim 2, characterized in that: The calibration method comprises step S5: in the coasting stop phase (H2), on a road surface with different slopes (θ), the motor regeneration torque (T M ) is set to 0 and adjusts the hydraulic braking torque (T H ), until a minimum hydraulic braking torque is determined that enables the vehicle (10) to stop on the road surface without slipping, and the product of the minimum hydraulic braking torque and the first safety factor is used as the hydraulic braking target torque (T HZ ) and according to the hydraulic brake target torque (T HZ ) adjust the first filter coefficient.

4. The calibration method according to claim 3, characterized in that: The slope (θ) and the corresponding hydraulic brake target torque (T HZ ) is recorded in the hydraulic brake target torque mapping table, wherein the corresponding hydraulic brake target torque (T HZ ); and / or The hydraulic brake target torque corresponding to a slope (θ) of 0 is set to the product of the hydraulic brake target torque corresponding to a preset slope range and a second safety factor; and / or The hydraulic brake target torque corresponding to the negative value of the gradient (θ) is set to the product of the hydraulic brake target torque corresponding to the absolute value of the gradient (θ) and the third safety factor.

5. The calibration method according to claim 3 or 4, characterized in that: The calibration method comprises step S6: in the coasting deceleration stage (H1), setting the initial filter coefficient to the motor regeneration torque (T M ) is calibrated; in the coasting stop stage (H2), when the slope (θ) of the road surface on which the vehicle (10) is located is equal to 0, the initial filter coefficient is set to the motor regeneration torque (T M ) is a calibration result of a second filter coefficient; in the coasting parking stage (H2), when the slope (θ) of the road surface on which the vehicle (10) is located is not equal to 0, in the hydraulic braking target torque (T HZ ) is additionally set based on the motor braking target torque (T MZ ) and according to the motor braking target torque (T MZ ) adjusts the motor regenerative torque (T M ) is used as the calibration result of the second filter coefficient.

6. The calibration method according to any one of claims 2 to 5, characterized in that: In the coasting stop phase (H2), the target deceleration curve and the initial filter coefficient are obtained through experiments on a road surface with a slope (θ) of 0.

7. The calibration method according to any one of the preceding claims, characterized in that The motor regenerative torque (T M ) and the hydraulic braking torque (T H )'s filter coefficients include at least a first-order filter coefficient and a gradient filter coefficient and are used to adjust the rising rate of the corresponding torque.

8. The calibration method according to any one of the preceding claims, characterized in that In the coasting regenerative braking condition, the required braking torque is calculated according to the speed (v) and deceleration of the vehicle (10), and the required braking torque is allocated to the motor regenerative torque (T M ) and the hydraulic braking torque (T H ).

9. The calibration method according to any one of the preceding claims, characterized in that During the driving process of the vehicle (10), when the accelerator pedal opening of the vehicle (10) is less than an accelerator pedal opening threshold and the brake pedal opening of the vehicle (10) is less than a brake pedal opening threshold, it is determined that the vehicle (10) is in the coasting regenerative braking condition; and / or The calibration method is used for a single-pedal mode of the vehicle (10).

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by one or more processors, the processors are capable of performing the calibration method according to any one of claims 1 to 9.

Images