Distributed drive electric vehicle energy recovery control method and related device
By optimizing the braking torque distribution through a distributed drive electric vehicle energy recovery control method, the problem of braking capacity attenuation caused by motor overheating is solved, achieving a balance between motor thermal safety and braking energy recovery, and improving range and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUHAN UNIV OF TECH
- Filing Date
- 2025-09-28
- Publication Date
- 2026-05-12
AI Technical Summary
During braking, prolonged or high-intensity power generation by the drive motor leads to increased copper losses, iron losses, and additional losses, causing the motor temperature to rise rapidly. This results in decreased output capacity and safety hazards, affecting the vehicle's braking performance and range.
By employing a distributed drive electric vehicle energy recovery control method, front and rear axle torque distribution, left and right wheel braking torque distribution, regenerative braking fuzzy control, and motor temperature regulation, the braking torque distribution is optimized. By combining regenerative braking and mechanical braking, the unity of motor thermal safety and braking energy recovery is achieved.
Improving the braking energy recovery rate alleviates the braking capacity reduction caused by motor overheating or damage, achieving a balance between extended range and motor thermal safety, and ensuring the safe operation of the motor under high energy recovery conditions.
Smart Images
Figure CN121246544B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of vehicle control technology, and in particular to a method and related equipment for energy recovery control of a distributed drive electric vehicle. Background Technology
[0002] With the rapid popularization of new energy vehicles, regenerative braking technology has become a key means to improve the energy utilization rate of the whole vehicle and extend the driving range. During braking, the drive motor converts the vehicle's kinetic energy into electrical energy and recovers it through a power generation mode, thereby significantly improving the vehicle's energy efficiency and driving range. In the pursuit of high regenerative braking efficiency, the drive motor needs to operate in power generation mode for a long time or at high intensity, which greatly increases its copper loss, iron loss and additional losses, causing the temperature of the motor windings and magnets to rise rapidly. Especially under frequent or forced braking conditions, it is very easy to cause a sharp accumulation of motor temperature. This not only leads to a decrease in motor output capacity and a reduction in overall braking efficiency, but may also cause serious safety hazards such as demagnetization, insulation aging and even thermal runaway.
[0003] In summary, the technical problems existing in the relevant technologies need to be improved. Summary of the Invention
[0004] The main objective of this application is to propose a distributed drive electric vehicle energy recovery control method and related equipment, which can effectively improve the braking energy recovery rate and alleviate the problem of vehicle braking capacity attenuation caused by motor overheating or damage, thereby achieving a balance between range improvement and motor thermal safety.
[0005] To achieve the above objectives, one aspect of this application proposes a distributed drive electric vehicle energy recovery control method, the method comprising:
[0006] Based on the total braking torque required by the vehicle, the torque is distributed between the front and rear axles according to a preset distribution rule to obtain the first torque distribution result; wherein, the preset distribution rule is determined by the braking intensity parameter;
[0007] Based on the first torque distribution result and the vehicle's additional yaw moment, the braking torque of the left and right wheels is distributed using a preset distribution algorithm to obtain the second torque distribution result;
[0008] Acquire preset vehicle state data, and then calculate the first regenerative braking torque ratio based on the preset vehicle state data using a regenerative braking fuzzy controller;
[0009] The motor control strategy is determined based on the drive motor temperature data, and then the first regenerative braking torque ratio is adjusted according to the motor control strategy to obtain the second regenerative braking torque ratio.
[0010] The target braking torque is calculated based on the second torque distribution result and the second regenerative braking torque ratio; wherein, the target braking torque includes regenerative braking torque and mechanical braking torque;
[0011] Energy recovery braking control is performed based on the regenerative braking torque and the mechanical braking torque.
[0012] In some embodiments, the step of distributing the total braking torque required by the vehicle to the front and rear axles according to a preset distribution rule to obtain a first torque distribution result includes:
[0013] When the vehicle braking intensity data is determined to be less than the preset braking intensity threshold, the front and rear axle torques are distributed according to the total braking torque required by the vehicle and a preset allocation priority to obtain the first torque allocation result; wherein, the preset allocation priority includes a higher allocation priority for the front axle than for the rear axle.
[0014] Alternatively, when it is determined that the vehicle braking intensity data is greater than or equal to the preset braking intensity threshold, the front and rear axle torques are distributed according to the total braking torque required by the vehicle through the I curve ratio to obtain the first torque distribution result.
[0015] In some embodiments, the step of distributing the braking torque of the left and right wheels according to the first torque distribution result and the vehicle's additional yaw moment using a preset distribution algorithm to obtain the second torque distribution result includes:
[0016] The desired yaw rate of the vehicle is calculated based on the steering wheel angle and the two-degree-of-freedom model of the vehicle, and then the additional yaw moment of the vehicle is determined based on the desired yaw rate of the vehicle.
[0017] Based on the first torque distribution result and the vehicle's additional yaw moment, the braking torque of the left and right wheels is distributed using the average distribution method to obtain the second torque distribution result.
[0018] In some embodiments, the step of acquiring preset vehicle state data and then calculating the first regenerative braking torque ratio based on the preset vehicle state data using a regenerative braking fuzzy controller includes:
[0019] Vehicle speed data is obtained through vehicle speed sensors;
[0020] Vehicle braking intensity data is obtained through an acceleration sensor;
[0021] Obtain battery SOC data through the battery management system;
[0022] The first regenerative braking torque ratio is determined based on the vehicle speed data, the vehicle braking intensity data, and the battery SOC data using a preset regenerative braking fuzzy rule.
[0023] In some embodiments, the step of determining a motor control strategy based on drive motor temperature data, and then adjusting the first regenerative braking torque ratio according to the motor control strategy to obtain a second regenerative braking torque ratio, includes:
[0024] The temperature data of the drive motor is dynamically acquired using a motor temperature sensor.
[0025] The motor operating temperature range is determined based on the drive motor temperature data and by using preset operating temperature range division parameters; wherein, the motor operating temperature range includes a normal operating range, a warning adjustment range, a power limit protection range, and an emergency shutdown range;
[0026] The motor control strategy is determined according to the motor operating temperature range, and then the first regenerative braking torque ratio is modified according to the motor control strategy to obtain the second regenerative braking torque ratio.
[0027] In some embodiments, the energy recovery braking control based on the regenerative braking torque and the mechanical braking torque includes:
[0028] A regenerative braking command is generated based on the regenerative braking torque, and then the regenerative braking command is sent to the motor controller to execute regenerative braking;
[0029] A mechanical braking command is generated based on the mechanical braking torque, and then the mechanical braking command is sent to the mechanical braking control unit to execute mechanical braking.
[0030] To achieve the above objectives, another aspect of this application provides a distributed drive electric vehicle energy recovery control device, the device comprising:
[0031] The first module is used to distribute the torque between the front and rear axles according to the total braking torque required by the vehicle using a preset distribution rule, thereby obtaining a first torque distribution result; wherein, the preset distribution rule is determined by the braking intensity parameter;
[0032] The second module is used to distribute the braking torque of the left and right wheels according to the first torque distribution result and the vehicle's additional yaw moment through a preset distribution algorithm to obtain the second torque distribution result.
[0033] The third module is used to acquire preset vehicle state data, and then calculate the first regenerative braking torque ratio based on the preset vehicle state data through the regenerative braking fuzzy controller.
[0034] The fourth module is used to determine the motor control strategy based on the drive motor temperature data, and then adjust the first regenerative braking torque ratio according to the motor control strategy to obtain the second regenerative braking torque ratio.
[0035] The fifth module is used to calculate the target braking torque based on the second torque distribution result and the second regenerative braking torque ratio; wherein the target braking torque includes regenerative braking torque and mechanical braking torque;
[0036] The sixth module is used for energy recovery braking control based on the regenerative braking torque and the mechanical braking torque.
[0037] To achieve the above objectives, another aspect of this application provides an electronic device, the electronic device comprising:
[0038] At least one processor;
[0039] At least one memory for storing at least one program;
[0040] When the at least one program is executed by the at least one processor, the at least one processor performs the method described above.
[0041] To achieve the above objectives, another aspect of the embodiments of this application proposes a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.
[0042] To achieve the above objectives, another aspect of this application provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.
[0043] The embodiments of this application include at least the following beneficial effects: This application provides a distributed drive electric vehicle energy recovery control method, device, electronic device, storage medium, and program product. This scheme distributes the front and rear axle torques according to the total braking torque required by the vehicle using a preset distribution rule determined by braking intensity parameters, obtaining a first torque distribution result. Next, based on the first torque distribution result and the vehicle's additional yaw moment, the embodiments of this invention distribute the left and right wheel braking torques using a preset distribution algorithm, obtaining a second torque distribution result. Simultaneously, the embodiments of this invention acquire preset vehicle state data, and then calculate a first regenerative braking torque ratio based on the preset vehicle state data using a regenerative braking fuzzy controller. Furthermore, a motor control strategy is determined based on drive motor temperature data, and the first regenerative braking torque ratio is adjusted according to the motor control strategy to obtain a second regenerative braking torque ratio. Finally, the embodiments of this invention calculate the target braking torque, including regenerative braking torque and mechanical braking torque, based on the second torque distribution result and the second regenerative braking torque ratio, achieving a balance between improved range and motor thermal safety. It is easy to understand that, in the embodiments of the present invention, the dual objectives of suppressing motor temperature rise and improving braking energy recovery efficiency are achieved through the coordinated adjustment of thermal state among multiple drive motors and the linkage control of braking and heat dissipation. This ensures the safe operation of the motor under high energy recovery conditions, effectively improves the braking energy recovery rate, and alleviates the problem of vehicle braking capacity attenuation caused by motor overheating or damage, thus achieving a balance between range improvement and motor thermal safety. Attached Figure Description
[0044] Figure 1 This is a flowchart of the energy recovery control method for a distributed drive electric vehicle provided in an embodiment of the present invention;
[0045] Figure 2 This is a schematic diagram of the architecture for distributed drive electric vehicle energy recovery control provided in an embodiment of the present invention;
[0046] Figure 3 This is a schematic diagram of the steps of energy recovery control for a distributed drive electric vehicle provided in an embodiment of the present invention;
[0047] Figure 4 This is a schematic diagram of the structure of the distributed drive electric vehicle energy recovery control device provided in an embodiment of the present invention;
[0048] Figure 5 This is a schematic diagram of the hardware structure of the electronic device provided in the embodiments of this application. Detailed Implementation
[0049] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.
[0050] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”
[0051] As used in this application, the terms "at least one", "multiple", "each", "any", etc., "at least one" includes one, two or more, "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the multiples.
[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.
[0053] Before providing a detailed description of the embodiments of this application, some of the nouns and terms involved in the embodiments of this application will be explained first. The nouns and terms involved in the embodiments of this application are subject to the following interpretations.
[0054] Regenerative braking refers to a braking technology that converts the kinetic energy of a vehicle or equipment into electrical energy and recycles it. Its core principle is to utilize the reverse power generation function of an electric motor during braking to convert mechanical energy into electrical energy and store it, thereby achieving energy saving and extending driving range.
[0055] With the rapid popularization of new energy vehicles, regenerative braking technology has become a key means to improve the energy utilization rate of the whole vehicle and extend the driving range. During braking, the drive motor converts the vehicle's kinetic energy into electrical energy and recovers it through a power generation mode, thereby significantly improving the vehicle's energy efficiency and driving range. In the pursuit of high regenerative braking efficiency, the drive motor needs to operate in power generation mode for a long time or at high intensity, which greatly increases its copper loss, iron loss and additional losses, causing the temperature of the motor windings and magnets to rise rapidly. Especially under frequent or forced braking conditions, it is very easy to cause a sharp accumulation of motor temperature. This not only leads to a decrease in motor output capacity and a reduction in overall braking efficiency, but may also cause serious safety hazards such as demagnetization, insulation aging and even thermal runaway.
[0056] In view of this, this application provides a distributed drive electric vehicle energy recovery control method, device, electronic device, storage medium, and program product. This solution distributes the front and rear axle torques according to the total braking torque required by the vehicle using a preset distribution rule determined by braking intensity parameters, obtaining a first torque distribution result. Next, based on the first torque distribution result and the vehicle's additional yaw moment, the embodiment distributes the left and right wheel braking torques using a preset distribution algorithm, obtaining a second torque distribution result. Simultaneously, the embodiment acquires preset vehicle state data, then calculates a first regenerative braking torque ratio using a regenerative braking fuzzy controller based on the preset vehicle state data, determines a motor control strategy based on drive motor temperature data, and adjusts the first regenerative braking torque ratio according to the motor control strategy to obtain a second regenerative braking torque ratio. Finally, the embodiment calculates the target braking torque, including regenerative braking torque and mechanical braking torque, based on the second torque distribution result and the second regenerative braking torque ratio. This effectively improves the braking energy recovery rate and alleviates the problem of vehicle braking capacity attenuation due to motor overheating or damage, achieving a balance between improved range and motor thermal safety.
[0057] The distributed drive electric vehicle energy recovery control method provided in this application relates to the field of vehicle control technology. This method can be applied to a terminal, a server, or software running on either a terminal or a server. In some embodiments, the terminal can be a smartphone, tablet, laptop, desktop computer, smart speaker, smartwatch, or in-vehicle terminal, but is not limited to these. The server can be configured as an independent physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms. The server can also be a node server in a blockchain network. The software can be an application implementing the distributed drive electric vehicle energy recovery control method, but is not limited to the above forms.
[0058] This application can be used in a wide variety of general-purpose or special-purpose computer system environments or configurations. Examples include: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics devices, network PCs, minicomputers, mainframe computers, and distributed computing environments including any of the above systems or devices. This application can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform specific tasks or implement specific abstract data types. This application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.
[0059] Figure 1 This is an optional flowchart of the distributed drive electric vehicle energy recovery control method provided in the embodiments of this application. Figure 1 The method may include, but is not limited to, steps S110 to S160.
[0060] Step S110: Based on the total braking torque required by the vehicle, distribute the torque between the front and rear axles according to a preset distribution rule to obtain the first torque distribution result. The preset distribution rule is determined by the braking intensity parameter.
[0061] Step S120: Based on the first torque distribution result and the vehicle's additional yaw moment, the braking torque of the left and right wheels is distributed using a preset distribution algorithm to obtain the second torque distribution result.
[0062] Step S130: Obtain preset vehicle state data, and then calculate the first regenerative braking torque ratio based on the preset vehicle state data through the regenerative braking fuzzy controller.
[0063] Step S140: Determine the motor control strategy based on the drive motor temperature data, and then adjust the first regenerative braking torque ratio according to the motor control strategy to obtain the second regenerative braking torque ratio.
[0064] Step S150: Calculate the target braking torque based on the second torque distribution result and the ratio of the second regenerative braking torque. The target braking torque includes both regenerative braking torque and mechanical braking torque.
[0065] Step S160: Perform energy recovery braking control based on regenerative braking torque and mechanical braking torque.
[0066] In the operation of this specific embodiment, the present invention first distributes the torque between the front and rear axles according to the total automatic torque required by the vehicle using a preset distribution rule, obtaining a first torque distribution result. Specifically, the total braking torque required by the vehicle in this embodiment refers to the sum of all braking torques required to ensure vehicle safety, which is achieved collaboratively by the braking torques generated by the brakes of each wheel. Accordingly, the present invention calculates the target deceleration of the vehicle and the total braking torque required by the vehicle based on the driver's brake pedal travel, and constructs a preset distribution rule using braking intensity parameters to distribute the total braking torque required by the vehicle to the front and rear axles, obtaining a first torque distribution result. Further, the present invention distributes the braking torque between the left and right wheels according to the first torque distribution result and the vehicle's additional yaw moment using a preset distribution algorithm, obtaining a second torque distribution result. Specifically, the vehicle's additional yaw moment in this embodiment refers to the external torque applied to the vehicle, generated by differential braking, active steering, or other actuators, used to change the vehicle's rotational state around its vertical axis and adjust the vehicle's actual yaw rate to approach the target value. Accordingly, in this embodiment of the invention, the braking torque is further distributed to the first torque distribution result by combining the vehicle's additional yaw moment with a preset distribution algorithm, so as to distribute the braking torque of the front and rear axles of the vehicle to the left and right wheels, thereby realizing the distribution of braking torque to each wheel of the vehicle.
[0067] Further, in this embodiment of the invention, preset vehicle state data is acquired, and then a first regenerative braking torque ratio is calculated using a regenerative braking fuzzy controller based on the preset vehicle state data. Specifically, in this embodiment of the invention, the preset vehicle state data refers to the vehicle's dynamic and energy state data, such as vehicle speed and charge status. Correspondingly, the fuzzy subset data of the regenerative braking fuzzy controller in this embodiment of the invention is constructed from preset vehicle state parameters. By acquiring the preset vehicle state data, the first regenerative braking torque ratio is determined through corresponding fuzzy rules. Next, in this embodiment of the invention, a motor control strategy is determined based on the drive motor temperature data, and then the first regenerative braking torque ratio is adjusted according to the motor control strategy to obtain a second regenerative braking torque ratio. Specifically, in this embodiment of the invention, the drive motor temperature data refers to the temperature of each drive motor winding. Different motor control strategies are pre-set in this embodiment of the invention, corresponding to the drive motor temperature range. Therefore, in this embodiment of the invention, the corresponding motor control strategy is determined by collecting drive motor temperature data, and then the regenerative braking torque allocation is adjusted according to the determined motor control strategy based on the first regenerative braking torque ratio to obtain the second regenerative braking torque ratio. Finally, in this embodiment of the invention, the target braking torque is calculated based on the second torque allocation result and the second regenerative braking torque ratio, and then energy recovery braking control is performed based on the target braking torque. Specifically, in this embodiment of the invention, the target braking torque includes regenerative braking torque and mechanical braking torque. Regenerative braking torque is the torque generated during braking or deceleration as the motor converts the vehicle's kinetic energy into electrical energy and stores it in the battery. Mechanical braking torque is the torque generated by the mechanical braking system. Accordingly, this embodiment of the invention allocates the regenerative braking torque and mechanical braking torque based on the second torque allocation result and the second regenerative braking torque ratio to obtain the target braking torque. Then, this embodiment of the invention executes the corresponding braking process according to the regenerative braking torque and mechanical braking torque, which can effectively improve the braking energy recovery rate and alleviate the problem of vehicle braking capacity attenuation caused by motor overheating or damage, achieving a balance between improved range and motor thermal safety.
[0068] To improve the accuracy and reliability of vehicle braking torque distribution, in some embodiments of the present invention, the front and rear axle torques are distributed according to a preset distribution rule based on the total braking torque required by the vehicle, to obtain a first torque distribution result, including but not limited to the following steps:
[0069] When the vehicle braking intensity data is determined to be less than the preset braking intensity threshold, the front and rear axle torques are distributed according to the vehicle's required total braking torque and a preset allocation priority, resulting in the first torque allocation result. The preset allocation priority includes a higher priority for the front axle than for the rear axle.
[0070] Alternatively, when the vehicle braking intensity data is determined to be greater than or equal to the preset braking intensity threshold, the front and rear axle torques are distributed according to the total braking torque required by the vehicle through the I curve ratio to obtain the first torque distribution result.
[0071] In this specific embodiment, the present invention determines the torque distribution method between the front and rear axles of a vehicle based on a preset braking intensity threshold and vehicle braking intensity data. Specifically, in this embodiment, vehicle braking intensity data refers to a physical quantity representing the vehicle's deceleration capacity or braking effect during braking, i.e., the ratio of the reduction in vehicle speed per unit time to the initial speed. Accordingly, when the vehicle braking intensity data is determined to be less than the preset braking intensity threshold, the present invention distributes the torque between the front and rear axles of the vehicle according to a preset allocation priority based on the total braking torque required by the vehicle, obtaining a first torque allocation result. In this embodiment, the preset allocation priority includes a higher allocation priority for the front axle than for the rear axle. For example, when the vehicle braking intensity data is determined to be less than the preset braking intensity threshold, the present invention distributes the torque between the front and rear axles according to a preset allocation priority. When a preset braking intensity threshold is reached, this embodiment of the invention prioritizes allocating the total braking torque required by the vehicle to the front axle. If the braking force on the front axle is insufficient, the excess braking torque is provided by the rear axle. Furthermore, when the vehicle braking intensity data is determined to be greater than or equal to the preset braking intensity threshold, this embodiment of the invention distributes the torque between the front and rear axles according to the vehicle's total braking torque required via an I-curve ratio, obtaining a corresponding first torque allocation result. For example, when the vehicle braking intensity data... In this embodiment of the invention, the front and rear axle torques are distributed according to the I curve ratio. The I curve formula is shown in equation (1) below:
[0072] (1)
[0073] Where, in the formula For vehicle quality; It is the acceleration due to gravity; The height of the car's center of gravity; This refers to the car's wheelbase. This is the distance from the car's center of gravity to the rear axle. The radius of the car tire; and These are the front and rear axle braking forces, respectively. and These are the braking torques for the front and rear axles, respectively.
[0074] To further improve the accuracy and reliability of vehicle braking torque distribution, in some embodiments of the present invention, the braking torque of the left and right wheels is distributed according to a preset distribution algorithm based on the first torque distribution result and the vehicle's additional yaw moment, to obtain a second torque distribution result, including but not limited to the following steps:
[0075] The desired yaw rate of the vehicle is calculated based on the steering wheel angle and the two-degree-of-freedom model of the vehicle, and then the additional yaw moment of the vehicle is determined based on the desired yaw rate.
[0076] Based on the first torque distribution result and the vehicle's additional yaw moment, the braking torque of the left and right wheels is distributed using the average distribution method to obtain the second torque distribution result.
[0077] In this specific embodiment, the present invention first calculates the desired yaw rate of the vehicle based on the steering wheel angle and the vehicle's two-degree-of-freedom model, and then determines the additional yaw moment of the vehicle based on the desired yaw rate. Specifically, the present invention calculates the desired yaw rate of the vehicle based on the steering wheel angle and the vehicle's two-degree-of-freedom model, and uses PID control to output the required additional yaw moment, i.e., the vehicle's additional yaw moment. The vehicle's two-degree-of-freedom model in the present invention is shown in the following equation (2):
[0078] (2)
[0079] Where, in the formula For vehicle quality; This refers to the longitudinal speed of the vehicle. Let Z be the moment of inertia of the car about the z-axis; and These are the distances from the car's center of gravity to the front and rear axles, respectively. and These are the lateral stiffness of the front and rear axles, respectively. This is the front wheel steering angle, calculated from the steering wheel angle. This refers to the yaw rate; It is the centroid sideslip angle.
[0080] Next, in this embodiment of the invention, the braking torque of the left and right wheels is distributed according to the first torque distribution result and the vehicle's additional yaw moment using an average distribution method to obtain the second torque distribution result. Specifically, in this embodiment of the invention, the average distribution method applies incremental torque to one side of the wheel while simultaneously reducing the equivalent torque on the opposite side of the wheel, and the torque modulation amounts of the front and rear wheels on the same side remain equal, so that the vehicle generates the desired yaw moment. The specific distribution formula is shown in the following formula (3) (taking counterclockwise yaw as an example):
[0081] (3)
[0082] Where, in the formula , , and These are the braking torques for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. The total braking torque required by the vehicle; Add yaw moment to the vehicle; This refers to the wheel track.
[0083] To improve the efficiency and robustness of regenerative braking torque distribution, in some embodiments of the present invention, preset vehicle state data is obtained, and then a first regenerative braking torque ratio is calculated based on the preset vehicle state data using a regenerative braking fuzzy controller, including but not limited to the following steps:
[0084] Vehicle speed data is obtained through vehicle speed sensors.
[0085] Vehicle braking intensity data is obtained through an acceleration sensor.
[0086] Battery SOC data is obtained through the battery management system.
[0087] The first regenerative braking torque ratio is determined based on vehicle speed data, vehicle braking intensity data, and battery SOC data through a preset regenerative braking fuzzy rule.
[0088] In this specific embodiment, the present invention acquires preset vehicle state data through corresponding sensors. Specifically, the present invention dynamically collects vehicle speed data through a vehicle speed sensor, acquires vehicle braking intensity data through an acceleration sensor, and acquires battery SOC data through a battery management system. The formula for acquiring vehicle braking intensity data through the acceleration sensor in this embodiment is shown in equation (4) below:
[0089] (4)
[0090] Where, in the formula Braking strength; This refers to the vehicle's longitudinal speed.
[0091] Furthermore, in this embodiment of the invention, the first regenerative braking torque ratio is determined based on the acquired vehicle speed data, vehicle braking intensity data, and battery SOC data using a preset regenerative braking fuzzy rule. Specifically, the input to the regenerative braking fuzzy controller in this embodiment of the invention is... , The output is the regenerative braking force distribution ratio Ke, where SOC is the vehicle braking intensity. The fuzzy subset is {low (L), medium (M), high (H)}, and the universe of discourse is [0,1]; vehicle speed The fuzzy subset is {low (L), medium (M), high (H)}, with a universe of discourse of [0,100]; the fuzzy subset of battery SOC is {low (L), medium (M), high (H)}, with a universe of discourse of [0,1]; the fuzzy subset of regenerative braking ratio coefficient Ke is {very low (LL), low (L), medium (M), high (H), very high (HH)}, with a universe of discourse of [0,1]. Accordingly, the preset regenerative braking fuzzy rules in this embodiment of the invention are shown in Table 1 below:
[0092] Table 1
[0093]
[0094] To achieve a balance between improved range and motor thermal safety, in some embodiments of the present invention, a motor control strategy is determined based on drive motor temperature data, and then the first regenerative braking torque ratio is adjusted according to the motor control strategy to obtain a second regenerative braking torque ratio, including but not limited to the following steps:
[0095] The temperature data of the drive motor is dynamically acquired by the motor temperature sensor.
[0096] The motor's operating temperature range is determined based on the drive motor temperature data and by dividing the range into preset operating temperature zones. This operating temperature range includes a normal operating zone, a warning adjustment zone, a power limit protection zone, and an emergency stop zone.
[0097] The corresponding motor control strategy is determined based on the motor's operating temperature range, and then the first regenerative braking torque ratio is modified according to the motor control strategy to obtain the second regenerative braking torque ratio.
[0098] In this specific embodiment, the present invention first dynamically acquires drive motor temperature data using a motor temperature sensor, and determines the motor's operating temperature range based on the drive motor temperature data using preset operating temperature range division parameters. Then, a corresponding motor control strategy is determined based on the motor's operating temperature range, and the first regenerative braking torque ratio is adjusted according to the motor control strategy to obtain a second regenerative braking torque ratio. Specifically, the present invention acquires the temperature of each drive motor winding using a motor temperature sensor to determine the motor's operating temperature range. The criteria for dividing the motor operating temperature range are as follows:
[0099] Normal working area: ;
[0100] Early warning adjustment zone: ;
[0101] Power-limited protection zone: ;
[0102] Emergency stop area: ;
[0103] in, This refers to the temperature of the motor windings. The starting temperature for the early warning adjustment zone is 130℃, for example. The starting temperature of the power-limited protection zone is 140℃, for example. The starting temperature for the emergency shutdown zone is 150℃, for example.
[0104] Accordingly, in this embodiment of the invention, based on the control strategy for different operating temperature ranges of the motor, the regenerative braking torque ratio of each motor is modified a second time and active cooling control is performed to obtain the second regenerative braking torque ratio. The control strategy for each operating temperature range is as follows:
[0105] a) The regenerative braking torque ratio Ke of the motor remains constant in the normal operating range, as shown in equation (5) below:
[0106] (5)
[0107] Where, in the formula This is the proportional coefficient for the regenerative braking torque after adjustment.
[0108] b) In the early warning adjustment zone control strategy, this embodiment of the invention first activates the motor active cooling system, and then calculates the amount by which the temperature exceeds the initial temperature of the early warning adjustment zone, as shown in the following formula (6):
[0109] (6)
[0110] Then adjust the regenerative braking torque ratio of this motor as shown in equation (7):
[0111] (7)
[0112] Where, in the formula , For the formula coefficient, it is necessary to satisfy the condition that the higher the temperature in the warning and control zone, the faster the proportional coefficient decreases. Take [value missing]. , For example.
[0113] c) In the control strategy implemented in the power-limited protection zone, the amount by which the temperature exceeds the starting temperature of the power-limited protection zone is first calculated, as shown in equation (8):
[0114] (8)
[0115] Secondly, adjust the operating power of the cooling system as shown in equation (9):
[0116] (9)
[0117] Where, in the formula This represents the maximum operating power of the cooling system.
[0118] Next, adjust the peak power of the motor as shown in equation (10):
[0119] (10)
[0120] Where, in the formula This represents the initial peak power of the motor. For example, let's take 0.1 as the coefficient of the formula.
[0121] Then, the motor cooperative heat dissipation strategy is activated in this embodiment of the invention, and the temporary proportional coefficient of the motor in the power limiting protection zone is as shown in the following formula (11):
[0122] (11)
[0123] Where, in the formula This is a temporary proportionality coefficient; The basic rate of decrease for each 1°C exceeding the limit for an overheated motor is taken as 0.06.
[0124] At the same time, calculate the availability of healthy motors. As shown in equation (12):
[0125] (12)
[0126] Where, in the formula Set the temperature of the healthy motor windings on the same side. Due to the limitation on the availability of healthy motors, if If no coordinated heat dissipation control is performed, the output will be directly controlled. As the motor in this work area .
[0127] Accordingly, if Then, as shown in equation (13):
[0128] (13)
[0129] in, The healthy motor capacity utilization coefficient represents the proportion that is actually willing / allowed to be received under the available capacity; The proportion of regenerative braking removed from the overheated motor; The actual share accepted by healthy motors; The final regenerative braking torque ratio for a healthy motor.
[0130] d) In the control strategy executed in the emergency stop zone, the embodiment of the present invention first adjusts the regenerative braking torque ratio of this motor, as shown in the following formula (14):
[0131] (14)
[0132] Then, adjust the operating power of the cooling system as shown in equation (15):
[0133] (15)
[0134] To achieve vehicle energy recovery control, improve braking energy recovery rate, and alleviate the problem of vehicle braking capacity attenuation due to motor overheating or damage, in some embodiments of the present invention, energy recovery braking control is performed based on regenerative braking torque and mechanical braking torque, including but not limited to the following steps:
[0135] The regenerative braking command is generated based on the regenerative braking torque, and then sent to the motor controller to execute the regenerative braking.
[0136] The mechanical braking command is generated based on the mechanical braking torque, and then sent to the mechanical braking control unit to execute the mechanical braking.
[0137] In this specific embodiment, the present invention first generates a regenerative braking command based on the regenerative braking torque, and then sends the regenerative braking command to the motor controller to execute regenerative braking. Simultaneously, it generates a mechanical braking command based on the mechanical braking torque, and then sends the mechanical braking command to the mechanical control unit to execute mechanical braking. Specifically, the present invention generates corresponding regenerative braking and mechanical braking commands by calculating the regenerative braking torque and mechanical braking torque of each wheel. Accordingly, the generated braking commands are sent to the motor controller (to execute regenerative braking) and the mechanical braking control unit (to execute mechanical braking), respectively. This leverages the advantage of independent control of multiple motors in a distributed drive electric vehicle, maintaining a high total braking energy recovery rate even when the regenerative braking capacity of some motors is limited due to thermal risks, thus alleviating the contradiction between high braking energy recovery rate and motor thermal safety in electric vehicles.
[0138] The following section provides a detailed introduction and explanation of the solutions in this embodiment of the invention, using a specific scenario of energy recovery control for distributed drive electric vehicles:
[0139] For example, refer to Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the architecture for distributed drive electric vehicle energy recovery control provided in an embodiment of the present invention. Figure 3This is a schematic diagram illustrating the steps of energy recovery control for a distributed drive electric vehicle provided in an embodiment of the present invention. Specifically, the embodiment first calculates the target deceleration and total braking torque required by the vehicle based on the driver's brake pedal travel, and then distributes the total braking torque required by the vehicle to the front and rear axles according to rules. Next, the embodiment uses an additional yaw moment to distribute the braking torque between the left and right wheels using an average distribution method. Simultaneously, the embodiment obtains the regenerative braking torque ratio of each wheel through regenerative braking fuzzy control, and acquires the winding temperature of each drive motor through temperature sensors to divide the motor temperature range. Then, based on the control strategy for different operating temperature ranges of the motor, the regenerative braking torque ratio of each motor is corrected a second time, and active cooling control is performed. Finally, the embodiment calculates the regenerative braking torque and mechanical braking torque of each wheel and sends them to the corresponding actuators for execution.
[0140] It is readily understood that the embodiments of the present invention employ a multi-motor collaborative heat load distribution strategy, rationally distributing high heat loads among multiple drive units, significantly reducing the heat accumulation rate of a single motor, effectively avoiding the risk of drive motor overheating and thermal runaway due to energy overload or heat accumulation, thereby improving the safety of the entire vehicle. Secondly, the embodiments of the present invention utilize the advantage of independent control of multiple motors in distributed drive electric vehicles, maintaining a high total braking energy recovery rate even when some motors have limited regenerative braking capability due to thermal risks, effectively alleviating the problems of high braking energy recovery rate and motor thermal safety in electric vehicles.
[0141] Please see Figure 4 This application also provides a distributed drive electric vehicle energy recovery control device that can implement the above-described method. The device includes:
[0142] The first module 210 is used to distribute the total braking torque required by the vehicle to the front and rear axles according to a preset distribution rule, thereby obtaining a first torque distribution result. The preset distribution rule is determined by the braking intensity parameter.
[0143] The second module 220 is used to distribute the braking torque of the left and right wheels according to the first torque distribution result and the vehicle's additional yaw moment through a preset distribution algorithm, so as to obtain the second torque distribution result.
[0144] The third module 230 is used to acquire preset vehicle state data, and then calculate the first regenerative braking torque ratio based on the preset vehicle state data through the regenerative braking fuzzy controller.
[0145] The fourth module 240 is used to determine the motor control strategy based on the drive motor temperature data, and then adjust the first regenerative braking torque ratio according to the motor control strategy to obtain the second regenerative braking torque ratio.
[0146] The fifth module 250 is used to calculate the target braking torque based on the second torque distribution result and the ratio of the second regenerative braking torque. The target braking torque includes both regenerative braking torque and mechanical braking torque.
[0147] Module 6, 260, is used for energy recovery braking control based on regenerative braking torque and mechanical braking torque.
[0148] It is understood that the content of the above method embodiments is applicable to the present device embodiments. The specific functions implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.
[0149] This application also provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the above-described method. This electronic device can be any smart terminal, including tablet computers, in-vehicle computers, etc.
[0150] It is understood that the content of the above method embodiments is applicable to this device embodiment. The specific functions implemented by this device embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.
[0151] Please see Figure 5 , Figure 5 The hardware structure of an electronic device according to another embodiment is illustrated. The electronic device includes:
[0152] The processor 310 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this application.
[0153] The memory 320 can be implemented as a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 320 can store the operating system and other applications. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory 320 and is called and executed by the processor 310 using the methods described in the embodiments of this application.
[0154] Input / output interface 330 is used to realize information input and output;
[0155] The communication interface 340 is used to enable communication and interaction between this device and other devices. Communication can be achieved through wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).
[0156] Bus 350 transmits information between various components of the device (e.g., processor 310, memory 320, input / output interface 330, and communication interface 340);
[0157] The processor 310, memory 320, input / output interface 330 and communication interface 340 are connected to each other within the device via bus 350.
[0158] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.
[0159] It is understood that the content of the above method embodiments is applicable to this storage medium embodiment. The specific functions implemented in this storage medium embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.
[0160] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.
[0161] It is understood that the content of the above method embodiments is applicable to the embodiments of this program product. The specific functions implemented by the embodiments of this program product are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.
[0162] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.
[0163] The distributed drive electric vehicle energy recovery control method, device, electronic device, storage medium, and program product provided in this application adjust the available regenerative braking torque of each drive motor of the distributed drive electric vehicle in real time through a motor thermal warning strategy, and reduce the temperature of the drive motor in a timely manner through the linkage control of the braking-cooling system. While ensuring the thermal safety of each drive motor, it maximizes the braking energy recovery rate, which can alleviate the mutual limitation problem between the high braking energy recovery rate of electric vehicles and the motor thermal safety protection strategy, and achieve the unity of range improvement and motor thermal safety.
[0164] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.
[0165] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than shown, or combine certain steps, or different steps.
[0166] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.
[0167] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or appropriate combinations thereof.
[0168] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0169] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.
[0170] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.
[0171] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0172] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.
[0173] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0174] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.
Claims
1. A distributed drive electric vehicle energy recovery control method, characterized in that, The method includes the following steps: Based on the total braking torque required by the vehicle, the torque is distributed between the front and rear axles according to a preset distribution rule to obtain the first torque distribution result; wherein, the preset distribution rule is determined by the braking intensity parameter; Based on the first torque distribution result and the vehicle's additional yaw moment, the braking torque of the left and right wheels is distributed using a preset distribution algorithm to obtain the second torque distribution result; Acquire preset vehicle state data, and then calculate the first regenerative braking torque ratio based on the preset vehicle state data using a regenerative braking fuzzy controller. The motor control strategy is determined based on the drive motor temperature data, and then the first regenerative braking torque ratio is adjusted according to the motor control strategy to obtain the second regenerative braking torque ratio. The target braking torque is calculated based on the second torque distribution result and the second regenerative braking torque ratio; wherein, the target braking torque includes regenerative braking torque and mechanical braking torque; Energy recovery braking control is performed based on the regenerative braking torque and the mechanical braking torque.
2. The method according to claim 1, characterized in that, The process of distributing the total braking torque required by the vehicle to the front and rear axles according to a preset distribution rule to obtain a first torque distribution result includes: When the vehicle braking intensity data is determined to be less than the preset braking intensity threshold, the front and rear axle torques are distributed according to the total braking torque required by the vehicle and a preset allocation priority to obtain the first torque allocation result; wherein, the preset allocation priority includes a higher allocation priority for the front axle than for the rear axle. Alternatively, when it is determined that the vehicle braking intensity data is greater than or equal to the preset braking intensity threshold, the front and rear axle torques are distributed according to the total braking torque required by the vehicle through the I curve ratio to obtain the first torque distribution result.
3. The method according to claim 1, characterized in that, The step of distributing the braking torque of the left and right wheels according to the first torque distribution result and the vehicle's additional yaw moment using a preset distribution algorithm to obtain the second torque distribution result includes: The desired yaw rate of the vehicle is calculated based on the steering wheel angle and the two-degree-of-freedom model of the vehicle, and then the additional yaw moment of the vehicle is determined based on the desired yaw rate of the vehicle. Based on the first torque distribution result and the vehicle's additional yaw moment, the braking torque of the left and right wheels is distributed using the average distribution method to obtain the second torque distribution result.
4. The method according to claim 1, characterized in that, The step of acquiring preset vehicle state data and then calculating the first regenerative braking torque ratio based on the preset vehicle state data using a regenerative braking fuzzy controller includes: Vehicle speed data is obtained through vehicle speed sensors; Vehicle braking intensity data is obtained through an acceleration sensor; Obtain battery SOC data through the battery management system; The first regenerative braking torque ratio is determined based on the vehicle speed data, the vehicle braking intensity data, and the battery SOC data using a preset regenerative braking fuzzy rule.
5. The method according to claim 1, characterized in that, The step of determining a motor control strategy based on drive motor temperature data, and then adjusting the first regenerative braking torque ratio according to the motor control strategy to obtain a second regenerative braking torque ratio, includes: The temperature data of the drive motor is dynamically acquired using a motor temperature sensor. The motor operating temperature range is determined based on the drive motor temperature data and by using preset operating temperature range division parameters; wherein, the motor operating temperature range includes a normal operating range, a warning adjustment range, a power limit protection range, and an emergency shutdown range; The motor control strategy is determined according to the motor operating temperature range, and then the first regenerative braking torque ratio is modified according to the motor control strategy to obtain the second regenerative braking torque ratio.
6. The method according to claim 1, characterized in that, The energy recovery braking control based on the regenerative braking torque and the mechanical braking torque includes: A regenerative braking command is generated based on the regenerative braking torque, and then the regenerative braking command is sent to the motor controller to execute regenerative braking; A mechanical braking command is generated based on the mechanical braking torque, and then the mechanical braking command is sent to the mechanical braking control unit to execute mechanical braking.
7. A distributed drive electric vehicle energy recovery control device, characterized in that, The device includes: The first module is used to distribute the torque between the front and rear axles according to the total braking torque required by the vehicle using a preset distribution rule, thereby obtaining a first torque distribution result; wherein, the preset distribution rule is determined by the braking intensity parameter; The second module is used to distribute the braking torque of the left and right wheels according to the first torque distribution result and the vehicle's additional yaw moment through a preset distribution algorithm to obtain the second torque distribution result. The third module is used to acquire preset vehicle state data, and then calculate the first regenerative braking torque ratio based on the preset vehicle state data through the regenerative braking fuzzy controller. The fourth module is used to determine the motor control strategy based on the drive motor temperature data, and then adjust the first regenerative braking torque ratio according to the motor control strategy to obtain the second regenerative braking torque ratio. The fifth module is used to calculate the target braking torque based on the second torque distribution result and the second regenerative braking torque ratio; wherein the target braking torque includes regenerative braking torque and mechanical braking torque; The sixth module is used for energy recovery braking control based on the regenerative braking torque and the mechanical braking torque.
8. An electronic device, characterized in that, include: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method as described in any one of claims 1 to 6.
9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 6.
10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 6.