Cruise power control method, device and vehicle

Abstract

The application provides a cruise power control method and device and a vehicle, and relates to the technical field of vehicle control. A speed deviation is obtained by obtaining a difference between a target speed and an actual speed of the vehicle. An acceleration of the vehicle is obtained. A power allowable fluctuation range is determined according to the speed deviation and the acceleration. The motor demand power in the cruise process is dynamically limited according to the power allowable fluctuation range to obtain the actual output motor control power. The power limiting range is dynamically adjusted based on the speed deviation and the acceleration. The power regulation is moderately relaxed when the road fluctuates to ensure that the vehicle speed follows, and the power regulation is narrowed when the state is stable to suppress the motor power fluctuation, so that the forced power limitation caused by the motor overheating is avoided, and the output capability of the vehicle in the cruise working condition is ensured to be stable.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, specifically to a cruise power control method, device, and vehicle. Background Technology

[0002] Maintaining a stable target speed and ensuring continuous and efficient output of the electric drive system during cruise control of electric vehicles such as pure electric light trucks is a core and challenging technical requirement in this field. The basic task of cruise control is to calculate the required power output of the drive motor in real time based on the deviation between the driver's set target speed and the actual vehicle speed, in order to overcome driving resistance and cope with random disturbances such as road slopes and wind resistance. However, real road environments are not ideally flat; frequent road surface undulations can lead to speed deviations and corresponding power compensation requirements. Therefore, the cruise system must respond quickly to speed deviations while simultaneously considering the thermal safety and power output capacity of the electric drive system, preventing over-adjustment from triggering protective power limiting and thus affecting the overall vehicle performance.

[0003] To achieve the aforementioned speed-following goal, a common strategy in related technologies is to fully open the power adjustment range of the drive motor to its maximum physical capacity, allowing the motor's power demand to dynamically change without constraint between its maximum generating power and maximum driving power. While this approach improves the vehicle's speed response to sudden disturbances, its inherent technical logic introduces a contradiction: in cruising scenarios with continuous or high-frequency slight fluctuations in road conditions, the excessively wide power adjustment range causes the motor's power demand to oscillate violently and frequently with speed deviations, manifesting as repeated high-rate charging and discharging switching. This violent power fluctuation causes a rapid rise in the temperature of the motor windings, power devices, and electrical circuits within a short period. Once the motor temperature reaches the preset maximum temperature limit, the control system is forced to forcibly limit the motor's power output for thermal protection, ultimately resulting in a significant limitation on the vehicle's continuous output capability during cruising, making stable following impossible, and even causing a sudden drop in power. Summary of the Invention

[0004] In view of this, this application provides a cruise power control method, device and vehicle, which solves the problem of overheating and power limitation caused by drastic fluctuations in motor power when electric vehicles cruise on undulating roads, and achieves the technical effect of protecting the continuous output capability of the electric drive system while maintaining cruise stability.

[0005] To achieve the above objectives, this application provides the following technical solution: obtaining the difference between the target speed and the actual speed of the vehicle to obtain the speed deviation; obtaining the acceleration of the vehicle; determining the allowable power fluctuation range based on the speed deviation and acceleration; and dynamically limiting the motor power demand during the cruising process based on the allowable power fluctuation range to obtain the actual output motor control power.

[0006] In one embodiment of this application, the allowable power fluctuation range is defined by an upper power limit and a lower power limit. Based on the allowable power fluctuation range, the motor power demand during the cruise process is dynamically limited to obtain the actual output motor control power. This includes: when the motor power demand is greater than or equal to the lower power limit and less than or equal to the upper power limit, determining the motor control power as the motor power demand; when the motor power demand is less than the lower power limit, determining the motor control power as the lower power limit; and when the motor power demand is greater than the upper power limit, determining the motor control power as the upper power limit.

[0007] In one embodiment of this application, determining the allowable power fluctuation range based on speed deviation and acceleration includes: obtaining a theoretical upper limit and a theoretical lower limit of the motor control power based on speed deviation and acceleration; obtaining the maximum driving power and maximum generating power of the vehicle motor; obtaining a power upper limit by comparing the theoretical upper limit with the maximum driving power and maximum generating power of the vehicle motor; obtaining a power lower limit by comparing the theoretical lower limit with the maximum driving power and maximum generating power of the vehicle motor; and determining the allowable power fluctuation range based on the power upper limit and power lower limit.

[0008] In one embodiment of this application, the theoretical upper limit and theoretical lower limit of the motor control power are obtained based on the speed deviation and acceleration, including: obtaining the power change coefficient based on the speed deviation and acceleration; obtaining the theoretical power demand of the vehicle; and calculating the power change coefficient and the theoretical power demand to obtain the theoretical upper limit and theoretical lower limit of the motor control power.

[0009] In one embodiment of this application, obtaining the power change coefficient based on speed deviation and acceleration includes: acquiring a pre-calibrated power change coefficient mapping map, wherein the mapping map is used to characterize the numerical relationship of the power change coefficient corresponding to different combinations of vehicle speed deviation and different acceleration; and obtaining the power change coefficient by querying the mapping map based on speed deviation and acceleration.

[0010] In one embodiment of this application, the theoretical upper limit and theoretical lower limit of the motor control power are calculated by calculating the power change coefficient and the theoretical required power, including: calculating the product of the theoretical required power and the power change coefficient to obtain the fluctuating power; calculating the sum of the theoretical required power and the fluctuating power to obtain the theoretical upper limit; and calculating the difference between the theoretical required power and the fluctuating power to obtain the theoretical lower limit.

[0011] In one embodiment of this application, the upper limit of power is obtained by comparing the theoretical upper limit with the maximum driving power and the maximum generating power of the vehicle motor, including: when the theoretical upper limit is greater than or equal to the maximum generating power and less than or equal to the maximum driving power, the upper limit of power is determined to be the theoretical upper limit; when the theoretical upper limit is less than the maximum generating power, the upper limit of power is determined to be the maximum generating power; when the theoretical upper limit is greater than the maximum driving power, the upper limit of power is determined to be the maximum driving power.

[0012] In one embodiment of this application, a power lower limit value is obtained by comparing a theoretical lower limit value with the maximum driving power and the maximum generating power of the vehicle motor. This includes: determining the power lower limit value as the theoretical lower limit value when the theoretical lower limit value is greater than or equal to the maximum generating power and less than or equal to the maximum driving power; determining the power lower limit value as the maximum generating power when the theoretical lower limit value is less than the maximum generating power; and determining the power lower limit value as the maximum driving power when the theoretical lower limit value is greater than the maximum driving power.

[0013] As a second aspect of this application, this application also provides a cruise power control device, comprising: a speed deviation acquisition module for acquiring the difference between the target speed and the actual speed of the vehicle to obtain a speed deviation; an acceleration acquisition module for acquiring the acceleration of the vehicle; a fluctuation amplitude determination module for determining the allowable power fluctuation amplitude based on the speed deviation and the acceleration; and a power limiting module for dynamically limiting the motor power demand during cruise based on the allowable power fluctuation amplitude to obtain the actual output motor control power.

[0014] As a third aspect of this application, this application also provides an electric vehicle, including: a power battery; a drive motor; and the aforementioned cruise power control device.

[0015] The cruise power control method provided in this application includes: obtaining the difference between the vehicle's target speed and actual speed to obtain the speed deviation; obtaining the vehicle's acceleration; determining the allowable power fluctuation range based on the speed deviation and acceleration; and dynamically limiting the motor's power demand during cruise based on the allowable power fluctuation range to obtain the actual output motor control power. It is noteworthy that by introducing the speed deviation and acceleration into the power adjustment logic, the allowable power fluctuation range is dynamically generated based on the combined state of the two, and this fluctuation range is used to limit the motor's power demand generated by cruise control. When the vehicle's dynamic changes are significant, the allowable power fluctuation range is adaptively widened to ensure vehicle speed following capability; when entering steady-state cruise, the range automatically narrows, effectively suppressing drastic fluctuations in motor power. This avoids a sharp rise in motor temperature due to frequent high-power charging and discharging, preventing the triggering of forced power limiting due to high motor temperature, thereby ensuring the vehicle's continuous and stable power output capability under cruise conditions. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 The diagram shown is a flowchart of a cruise power control method provided in an embodiment of this application.

[0018] Figure 2 The diagram shown is a flowchart of a vehicle speed power control provided in an embodiment of this application.

[0019] Figure 3 The diagram shown is a schematic diagram of a cruise power control device provided in an embodiment of this application. Detailed Implementation

[0020] In the field of electric vehicle cruise control technology, to adjust the motor output power during vehicle cruise control, a common approach is to open the motor power adjustment range to its maximum capacity, allowing the controller to freely adjust the motor's required power between the maximum driving power and the maximum generating power based on vehicle speed feedback. This solution calculates the motor's required power using a speed-based PID (Proportional-Integral-Derivative Control) algorithm and directly uses it as the motor control power output, without setting additional power fluctuation limits based on operating conditions.

[0021] However, the strategy commonly adopted in related technologies is to fully open the power regulation range of the drive motor to the maximum boundary of its physical capabilities, that is, to allow the motor's power demand to change dynamically without constraints between the maximum power generation and the maximum power drive. While this approach improves the vehicle speed response speed to sudden disturbances, its inherent technical logic also introduces contradictions.

[0022] The inventors of this application have proposed a cruise power control method: by introducing speed deviation and acceleration as feedforward variables, the allowable power fluctuation range is dynamically generated, and this range is used to limit the motor power demand generated by cruise control. Thus, without significantly sacrificing the vehicle speed following ability, the method effectively suppresses drastic fluctuations in motor power, avoids abnormal rise in motor temperature and forced power limiting, and solves the problem of overheating and power limiting caused by drastic fluctuations in motor power when electric vehicles cruise on undulating roads. This method achieves the technical effect of maintaining cruise stability while protecting the continuous output capability of the electric drive system.

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] As a first aspect of this application, this application provides a cruise power control method. Figure 1 The diagram shown is a flowchart of a cruise power control method provided in an embodiment of this application. Figure 1 As shown, the method includes: S101, obtain the difference between the vehicle's target speed and actual speed to obtain the speed deviation; Specifically, during cruise control in an electric vehicle, the driver or adaptive cruise control system sets a target speed V_req to be maintained. Simultaneously, the vehicle controller collects the vehicle's actual speed V_act in real time via vehicle speed sensors or wheel speed sensors. The speed deviation VelD is obtained by calculating the absolute value of the difference between the target speed and the actual speed, i.e., VelD = abs(V_req – V_act). This speed deviation reflects the degree to which the current actual vehicle speed deviates from the cruise target.

[0025] As a specific implementation, the vehicle controller can read the target speed set by the cruise function via the CAN (Controller Area Network) bus and calculate the actual speed from the vehicle speed sensor pulse signal. By calculating the absolute value of the difference between the target speed and the actual speed, this speed deviation can be used as one of the feedforward inputs to subsequently determine the allowable power fluctuation range. Its magnitude reflects the urgency of the vehicle's speed adjustment: the larger the deviation, the more significant the change in road resistance usually means that the system needs a wider power adjustment range to ensure speed following.

[0026] S102, obtain the vehicle's acceleration; Specifically, during actual driving, the rate of change of vehicle speed, i.e., acceleration Acc, can sensitively reflect the impact of dynamic disturbances such as road slope, wind resistance, and road rolling resistance.

[0027] Specifically, acceleration Acc can be obtained by performing differentiation or difference operations on the actual vehicle speed V_act. For example, this can be achieved within a predetermined time window. It is calculated as the ratio of the change in vehicle speed within the time window to the change in the time window, i.e., Acc = abs( (V_act_Ta-V_act_T0) / ), where V_act_T0 and V_act_Ta are the actual vehicle speed sampling values ​​at the start and end times of the time window, respectively, and ta can be, for example, 200ms.

[0028] The introduction of acceleration allows the determination of power fluctuation amplitude not only to depend on the current speed deviation, but also to predict the trend of vehicle speed change, thereby enabling appropriate adjustments to the power adjustment range in the early stages of disturbance.

[0029] S103, determine the allowable power fluctuation range based on speed deviation and acceleration; Specifically, the aforementioned allowable power fluctuation range can be used to represent a dynamically generated constraint range to suppress drastic fluctuations in motor power, and is used to limit the initial motor power demand.

[0030] Examples include, but are not limited to, a power range defined by an upper boundary value and a lower boundary value. This range is determined at least based on speed deviation and acceleration. Specifically, the power adjustment range can be appropriately widened when a rapid response to vehicle speed deviation is required, and the adjustment range can be automatically narrowed during steady-state cruising.

[0031] Drastic fluctuations in motor power are the main cause of rapid increases in motor temperature, triggering overheating and forced power limiting. To avoid such fluctuations, this application allows for dynamic adjustment within a reasonable range. This allowable fluctuation range is the aforementioned allowable power fluctuation amplitude. The core principle is to dynamically adjust the magnitude of this amplitude based on the vehicle's current dynamic state (including speed deviation and acceleration).

[0032] For example, when the road slope changes or there is a gust of wind, causing the vehicle speed to deviate from the target and the acceleration to increase, the system appropriately relaxes the allowable power fluctuation range to ensure that there is enough power to correct the speed deviation; while when the vehicle is cruising stably on a flat road and the speed deviation and acceleration are very small, the system automatically narrows the fluctuation range to suppress the excess power fluctuations that may be generated by the cruise PID controller and other components, thereby preventing the temperature rise caused by repeated charging and discharging of the motor.

[0033] As one implementation method, determining the allowable power fluctuation range can specifically include: obtaining the power change coefficient f based on the speed deviation VelD and acceleration Acc by querying a pre-calibrated power change coefficient mapping map; acquiring the theoretical required power Pwr_req calculated based on the drag coefficient, vehicle weight, gradient, and target vehicle speed; and then using f and Pwr_req to calculate the upper and lower power limits, which together define the allowable power fluctuation range. This process allows the upper and lower limits of the fluctuation range to be adjusted based on the theoretical required power. It should be noted that the above determination method is only a preferred example, and other methods that can generate fluctuation ranges based on speed deviation and acceleration and achieve dynamic constraints on motor power also fall within the scope of protection of this application.

[0034] S104 dynamically limits the motor's power demand during cruise based on the allowable power fluctuation range, in order to obtain the actual output motor control power.

[0035] Specifically, the power demand of the motor mentioned above is the power command that the cruise controller expects the motor to output, which is directly calculated by the cruise controller based on the vehicle speed closed-loop control (such as PID control).

[0036] During cruise control, the vehicle controller typically includes a cruise PID controller, which generates a preliminary motor power demand Pwr based on the speed deviation. This demand power, directly driving the motor, could ideally ensure vehicle speed response, but it may also fluctuate significantly due to factors such as overshoot and sensor noise. In this case, the demand power can be dynamically limited based on the allowable power fluctuation range.

[0037] Specifically, when the value of Pwr is within the allowable range defined by the fluctuation amplitude, the original required power can be maintained and output directly. When Pwr exceeds the high or low side of the allowable range, it is forcibly limited to the upper or lower boundary of the allowable range, thereby outputting the constrained motor control power PwrOut. This dynamic limiting logic can prevent sending power commands to the motor that exceed the necessary level for the current operating condition, ensuring that the motor power remains within a relatively stable range while meeting the vehicle speed following requirements. This suppresses motor heating and avoids triggering forced power limiting due to high motor temperature.

[0038] Meanwhile, since the fluctuation amplitude itself is based on real-time updates of velocity deviation and acceleration, the constraint force can be seamlessly switched according to the working conditions, with strong amplitude limitation in steady state and moderate relaxation in dynamic state.

[0039] The cruise power control method provided in this application includes: obtaining the difference between the vehicle's target speed and actual speed to obtain the speed deviation; obtaining the vehicle's acceleration; determining the allowable power fluctuation range based on the speed deviation and acceleration; and dynamically limiting the motor's power demand during cruise based on the allowable power fluctuation range to obtain the actual output motor control power. It is noteworthy that by introducing the speed deviation and acceleration into the power adjustment logic, the allowable power fluctuation range is dynamically generated based on the combined state of the two, and this fluctuation range is used to limit the motor's power demand generated by cruise control. When the vehicle's dynamic changes are significant, the allowable power fluctuation range is adaptively widened to ensure vehicle speed following capability; when entering steady-state cruise, the range automatically narrows, effectively suppressing drastic fluctuations in motor power. This avoids a sharp rise in motor temperature due to frequent high-power charging and discharging, preventing the triggering of forced power limiting due to high motor temperature, thereby ensuring the vehicle's continuous and stable power output capability under cruise conditions.

[0040] In one embodiment of this application, the allowable power fluctuation range is defined by an upper power limit and a lower power limit. Based on the allowable power fluctuation range, the motor power demand during the cruise process is dynamically limited to obtain the actual output motor control power. This includes: when the motor power demand is greater than or equal to the lower power limit and less than or equal to the upper power limit, determining the motor control power as the motor power demand; when the motor power demand is less than the lower power limit, determining the motor control power as the lower power limit; and when the motor power demand is greater than the upper power limit, determining the motor control power as the upper power limit.

[0041] Specifically, the aforementioned upper and lower power limits constitute the upper and lower boundaries of the allowable power fluctuation range. Specifically, they can be defined as follows: based on the theoretical power demand, scaled proportionally using a power variation coefficient, and then corrected for by the maximum driving power and maximum generating power of the motor, resulting in the final clamping boundaries. The upper power limit restricts the maximum output power of the motor, while the lower power limit restricts the minimum output power of the motor.

[0042] To further optimize the dynamic limiting performance of motor power demand, and to make the limiting process clear, reliable and easy to implement in engineering, as a preferred solution, the allowable power fluctuation range is defined by the upper limit value Pwr_UpOut and the lower limit value Pwr_DownOut.

[0043] Specifically, when the motor's required power Pwr is greater than or equal to the lower power limit Pwr_DownOut and less than or equal to the upper power limit Pwr_UpOut, it indicates that the required power is within the allowable fluctuation range. In this case, the motor control power PwrOut is determined to be Pwr itself, and the system does not intervene. When Pwr is less than the lower power limit Pwr_DownOut, it indicates that the required power has fallen below the lower limit of the allowable range. In this case, the system forcibly sets PwrOut to the lower power limit Pwr_DownOut to prevent the motor's power generation from being too high or its output power from being too low. When Pwr is greater than the upper power limit Pwr_UpOut, it indicates that the required power has exceeded the upper limit of the allowable range. In this case, PwrOut is forcibly set to the upper power limit Pwr_UpOut, thereby clamping the motor drive power within a safe range.

[0044] The above-described judgment method reliably and strictly limits the final output motor control power within the range defined by the upper and lower power limits, thereby preventing the motor power from exceeding the limits and ensuring the effective execution of the temperature control strategy. Furthermore, since the upper and lower limits are dynamically changing, this limit is not a fixed hard limit, but a flexible constraint that can adaptively adjust according to operating conditions.

[0045] In one embodiment of this application, determining the allowable power fluctuation range based on speed deviation and acceleration includes: obtaining a theoretical upper limit and a theoretical lower limit of the motor control power based on speed deviation and acceleration; obtaining the maximum driving power and maximum generating power of the vehicle motor; obtaining a power upper limit by comparing the theoretical upper limit with the maximum driving power and maximum generating power of the vehicle motor; obtaining a power lower limit by comparing the theoretical lower limit with the maximum driving power and maximum generating power of the vehicle motor; and determining the allowable power fluctuation range based on the power upper limit and power lower limit.

[0046] Specifically, the aforementioned theoretical upper and lower limits can be represented as preliminary boundaries of the allowable power fluctuation range calculated through vehicle speed deviation and acceleration. Examples include, but are not limited to: taking the theoretical demand power as the center, multiplying it by the power change coefficient to obtain the fluctuating power, and then adding and subtracting it from the theoretical demand power to obtain the upper and lower power limits.

[0047] The aforementioned maximum driving power and maximum generating power can be expressed as the power limit that the motor can safely and continuously output in driving and generating states, determined by the physical capabilities of the electric drive system.

[0048] The process of determining the allowable power fluctuation range based on speed deviation and acceleration can be implemented in multiple stages. In a further preferred embodiment, to balance vehicle dynamic response and motor physical safety, the process can be divided into two stages: first, a theoretical boundary is generated based on vehicle dynamics, and then corrections are made using the motor's own capability limits.

[0049] Specifically, the allowable power fluctuation range is determined based on speed deviation and acceleration, including: First, the theoretical upper limit value Pwr_Up and theoretical lower limit value Pwr_Down of the motor control power are obtained based on the speed deviation VelD and acceleration Acc; simultaneously, the maximum driving power DrvPwrLimt and the maximum generating power GenPwrLimt of the vehicle motor are acquired. The maximum driving power and the maximum generating power represent the maximum driving power and the maximum generating power that the motor can safely output under the current state, respectively. Then, the system compares the theoretical upper limit value Pwr_Up with the maximum driving power DrvPwrLimt and the maximum generating power GenPwrLimt to obtain the power upper limit value Pwr_UpOut after capacity limiting; similarly, the theoretical lower limit value Pwr_Down is obtained by comparing the theoretical lower limit value Pwr_Down with the maximum driving power and the maximum generating power. Finally, Pwr_UpOut and Pwr_DownOut are used together to determine the allowable power fluctuation range.

[0050] This two-tiered boundary generation method ensures that the fluctuation amplitude fully reflects the dynamic road demands represented by vehicle speed deviation and acceleration, while never exceeding the actual physical execution capability of the motor. For example, if the theoretical boundary expands too wide due to a large vehicle speed deviation, potentially exceeding the motor's driving or generating limits, the motor capability constraint will limit it within a safe range, thereby suppressing the rise in motor temperature and protecting the hardware safety of the electric drive system.

[0051] In one embodiment of this application, the theoretical upper limit and theoretical lower limit of the motor control power are obtained based on the speed deviation and acceleration, including: obtaining the power change coefficient based on the speed deviation and acceleration; obtaining the theoretical power demand of the vehicle; and calculating the power change coefficient and the theoretical power demand to obtain the theoretical upper limit and theoretical lower limit of the motor control power.

[0052] Specifically, the aforementioned power variation coefficient is a parameter used to reflect the degree of relaxation in the allowable deviation of motor power from the theoretical power requirement under the current operating conditions. Examples include, but are not limited to, a numerical coefficient f obtained by looking up a pre-calibrated two-dimensional mapping graph with speed deviation and acceleration as inputs. This coefficient f directly determines the scaling ratio of the allowable power fluctuation relative to the theoretical power requirement.

[0053] The aforementioned theoretical power requirement can be expressed as the mechanical power that theoretically needs to overcome driving resistance to maintain the vehicle's stable travel at the target speed under current road conditions. Examples include, but are not limited to, power values ​​calculated using vehicle dynamics equations based at least on vehicle mass, road gradient, rolling resistance coefficient, and target vehicle speed.

[0054] Based on the theoretical upper and lower limits obtained from the speed deviation and acceleration, this application provides a specific implementation combining the theoretical power demand and the power variation coefficient. In this preferred embodiment, the power variation coefficient f is first obtained based on the speed deviation VelD and the acceleration Acc. Then, the theoretical power demand Pwr_req of the vehicle is obtained. The theoretical power demand can be understood as the power that the motor theoretically needs to provide when the vehicle is cruising at the target speed V_req under ideal conditions of no wind and flat road.

[0055] As an example, Pwr_req can be calculated using the vehicle dynamics formula: Pwr_req=(m·g·sinα+u0·m·g·cosα +u1·m·g·cosα·V_req+u2·V_req²)·V_req / 3600, where u0 is the rolling resistance constant, u1 is the rolling resistance linear term, u2 is the drag coefficient, m is the vehicle weight, α is the gradient, and V_req is the target speed. Then, the power variation coefficient f and the theoretical power requirement Pwr_req are calculated to obtain the theoretical upper limit Pwr_Up and the theoretical lower limit Pwr_Down.

[0056] By using the theoretical power requirement as a benchmark and quantifying the combined effects of vehicle speed and acceleration into a power change coefficient, the theoretical boundary is always scaled around the power required to maintain cruising, thereby improving the accuracy of fluctuation suppression.

[0057] In one embodiment of this application, obtaining the power change coefficient based on speed deviation and acceleration includes: acquiring a pre-calibrated power change coefficient mapping map, wherein the mapping map is used to characterize the numerical relationship of the power change coefficient corresponding to different combinations of vehicle speed deviation and different acceleration; and obtaining the power change coefficient by querying the mapping map based on speed deviation and acceleration.

[0058] Specifically, the aforementioned power change coefficient mapping diagram is a pre-constructed set of data or functional relationships used to query and output the corresponding power change coefficient based on at least two input variables (such as velocity deviation and acceleration).

[0059] When further refining the method for obtaining the power change coefficient, this application preferably uses a pre-calibrated power change coefficient mapping map for lookup. This mapping map is stored in the memory of the vehicle controller, and through extensive real-vehicle calibration tests, it has established the numerical relationship between the power change coefficient f corresponding to different combinations of vehicle speed deviation VelD and acceleration Acc. During real-time operation, the vehicle controller uses the currently calculated VelD and Acc as input indexes to quickly obtain the appropriate f for the current dynamic by querying this two-dimensional mapping map.

[0060] Using a lookup table method ensures the real-time performance of the control algorithm. It's understandable that the mapping graph's dimension is not limited to two dimensions; it can also incorporate other parameters such as vehicle speed and load to further improve adaptability.

[0061] In one embodiment of this application, the theoretical upper limit and theoretical lower limit of the motor control power are calculated by calculating the power change coefficient and the theoretical required power, including: calculating the product of the theoretical required power and the power change coefficient to obtain the fluctuating power; calculating the sum of the theoretical required power and the fluctuating power to obtain the theoretical upper limit; and calculating the difference between the theoretical required power and the fluctuating power to obtain the theoretical lower limit.

[0062] Specifically, for calculating the theoretical lower and lower limits, a preferred approach is to use a symmetric extension based on fluctuating power.

[0063] Specifically, the product of the theoretical demand power Pwr_req and the power variation coefficient f can be calculated to obtain the fluctuating power ΔPwr = Pwr_req·f. Then, the theoretical demand power and the fluctuating power are added together to obtain the theoretical upper limit value Pwr_Up = Pwr_req + ΔPwr = (1 + f)·Pwr_req; the fluctuating power is subtracted from the theoretical demand power to obtain the theoretical lower limit value Pwr_Down = Pwr_req - ΔPwr = (1 - f)·Pwr_req. Thus, the theoretical lower and lower limits are symmetrically distributed around Pwr_req. When f increases, the allowable power bandwidth widens uniformly to both sides; when f decreases, the bandwidth narrows uniformly towards the center.

[0064] This symmetrical constraint ensures that any fluctuations in motor power are suppressed equally on both sides of the reference power, guaranteeing the smoothness of power regulation.

[0065] In one embodiment of this application, the upper limit of power is obtained by comparing the theoretical upper limit with the maximum driving power and the maximum generating power of the vehicle motor, including: when the theoretical upper limit is greater than or equal to the maximum generating power and less than or equal to the maximum driving power, the upper limit of power is determined to be the theoretical upper limit; when the theoretical upper limit is less than the maximum generating power, the upper limit of power is determined to be the maximum generating power; when the theoretical upper limit is greater than the maximum driving power, the upper limit of power is determined to be the maximum driving power.

[0066] Specifically, in the section involving motor capacity constraints, the correction method for the theoretical upper limit value Pwr_Up is as follows: When the theoretical upper limit value is within the range of being greater than or equal to the maximum generating power GenPwrLimt and less than or equal to the maximum driving power DrvPwrLimt, it indicates that the theoretical boundary falls completely within the motor's safe range, and the power upper limit value Pwr_UpOut is directly determined as Pwr_Up; when the theoretical upper limit value is less than the maximum generating power, it indicates that if this upper limit value is used, the minimum generating power constraint of the motor may not be met when the demand power is high, leading to the risk of overvoltage in the electrical system, so the power upper limit value is determined to be the maximum generating power GenPwrLimt; when the theoretical upper limit value is greater than the maximum driving power, sending it to the motor controller may cause the drive system to overload, so the power upper limit value is determined to be the maximum driving power DrvPwrLimt.

[0067] This comparison and clamping operation can adjust the power limit to a range that the motor can safely execute, effectively ensuring the operational safety of the electric drive system during the high power fluctuation suppression process.

[0068] In one embodiment of this application, a power lower limit value is obtained by comparing a theoretical lower limit value with the maximum driving power and the maximum generating power of the vehicle motor. This includes: determining the power lower limit value as the theoretical lower limit value when the theoretical lower limit value is greater than or equal to the maximum generating power and less than or equal to the maximum driving power; determining the power lower limit value as the maximum generating power when the theoretical lower limit value is less than the maximum generating power; and determining the power lower limit value as the maximum driving power when the theoretical lower limit value is greater than the maximum driving power.

[0069] Specifically, similarly, the correction method for the theoretical lower limit value Pwr_Down is as follows: when the theoretical lower limit value is between GenPwrLimt and DrvPwrLimt, the power lower limit value Pwr_DownOut is determined to be Pwr_Down; when the theoretical lower limit value is less than the maximum power generation, it is corrected to the maximum power generation to prevent the motor from suddenly generating power too deeply due to an excessively low lower limit; when the theoretical lower limit value is greater than the maximum drive power, it is corrected to the maximum drive power to ensure that the minimum drive power requirement can be met even at the lower limit.

[0070] Through the above modifications, the lower limit of power is always within the range of energy recovery and drive that the motor can safely perform, ensuring the smoothness and electrical safety of the vehicle during cruise deceleration and power adjustment.

[0071] Figure 2 The diagram shown is a flowchart of a vehicle speed power control method according to an embodiment of this application. Figure 2 As shown, it includes: (1) Based on the drag coefficients (u0, u1, u2), vehicle weight m, gradient α, and target vehicle speed V req The theoretical power requirement is obtained as follows: Pwr_req=(m·g·sinα+u0·m·g·cosα +u1·m·g·cosα·V_req+u2·V_req²)·V_req / 3600.

[0072] (2) Based on the target vehicle speed V req The actual vehicle speed Vact is the speed difference VelD = abs(Vreq-Vact), and the acceleration Acc = abs((Vact_Ta-Vact_T0) / ta) is updated in real time during the time period ta. By using the calibrated allowable power change coefficient map (i.e., inputting the speed difference and acceleration), the required power change coefficient f at this time is obtained.

[0073] (3) Obtain the upper limit Pwr of motor power control Up Lower limit Pwr Down Among them, Pwr Up =(1+f) Pwr req ,Pwr Down =(1-f) Pwr req .

[0074] (4) Based on the maximum power limit of the motor drive DrvPwrLimt and the maximum power limit of the motor generator GenPwrLimt, the upper and lower limits of the motor power control are obtained, and the upper limit of the motor power Pwr after the motor capacity limit is obtained. Up Out, lower limit Pwr Down Out.

[0075] For the upper limit of motor power Pwr Up Out: If GenPwrLimt≤Pwr Up If ≤DrvPwrLimt, then Pwr Up Out = Pwr Up ; If Pwr Up <GenPwrLimt, then Pwr Up Out = GenPwrLimt; If Pwr Up >DrvPwrLimt, then Pwr Up Out = DrvPwrLimt; For the lower limit of motor power Pwr Down Out: If GenPwrLimt≤Pwr Down If ≤DrvPwrLimt, then Pwr Down Out = Pwr Down ; If Pwr Down <GenPwrLimt, then Pwr Down Out = GenPwrLimt; If Pwr Down >DrvPwrLimt, then Pwr Down Out = DrvPwrLimt; (5) The motor power obtained based on the vehicle speed PID needs to be Pwr, according to the upper limit Pwr Up Out, lower limit Pwr Down The Out limit is used to obtain the actual controlled power PwrOut of the motor. If Pwr Down Out≤Pwr≤Pwr Up If Out, then PwrOut = Pwr; If Pwr < Pwr Down Out, PwrOut = Pwr Down Out; If Pwr > Pwr Up Out, then PwrOut = Pwr Up Out.

[0076] The following example illustrates this with a specific application scenario.

[0077] A fully loaded pure electric light truck is using adaptive cruise control on a highway, with a target speed set at 90 km / h. The vehicle is traveling on a mountainous highway section with gentle inclines and undulating surfaces. In this scenario, the vehicle controller acquires the actual vehicle speed in real time from the vehicle speed sensor and calculates the absolute difference between the target speed and the actual speed to obtain the speed deviation. Simultaneously, the controller performs a differential calculation on the actual speed over a 200-millisecond time window to obtain the vehicle's longitudinal acceleration. These two parameters constitute the core inputs characterizing the vehicle's real-time dynamics.

[0078] As the vehicle enters a long uphill section, road resistance increases, and the actual vehicle speed gradually falls below the target speed, resulting in a significant increase in speed deviation. Acceleration also shows a positive increasing trend, indicating that the vehicle speed is further deviating from the target. The controller immediately uses the current speed deviation and acceleration as an index to look up a pre-calibrated and stored two-dimensional mapping of power change coefficients. The lookup operation quickly obtains a power change coefficient adapted to the current disturbance, for example, an output value of 0.2. Simultaneously, the controller calculates the theoretical power requirement in real time according to the vehicle's mass, rolling resistance coefficient, air resistance coefficient, gradient, and target speed, using vehicle dynamics formulas; for example, 150 kilowatts at the current gradient and speed.

[0079] Next, the controller calculates the product of the theoretical power demand and the power variation coefficient, obtaining a fluctuating power of 30 kW. Adding the theoretical power demand to the fluctuating power yields a theoretical upper limit of 180 kW; subtracting the fluctuating power from the theoretical power demand yields a theoretical lower limit of 120 kW. These theoretical upper and lower limits are symmetrically distributed around the theoretical power demand, providing a dynamic benchmark for subsequent power constraints. Considering the physical limits of the motor itself, the controller also obtains the current maximum drive power (e.g., 200 kW) and maximum generator power (e.g., -50 kW) from the motor controller. The controller compares the theoretical upper limit of 180 kW with the maximum drive and generator power. Since 180 kW falls between the maximum generator and drive power, it is directly determined as the upper power limit of 180 kW. The theoretical lower limit of 120 kW also falls within this range, therefore, the lower power limit is determined to be 120 kW. Thus, the allowable power fluctuation range is defined as 120 kW to 180 kW.

[0080] During cruise control, the vehicle's PID controller generates an initial motor power demand based on the speed deviation. Assuming that this demand surges to 190 kW due to overshoot and sensor noise, the controller compares this demand with the upper and lower power limits. Since 190 kW exceeds the upper power limit of 180 kW, the controller clamps the actual motor control power output to 180 kW. Conversely, if the demand drops to 110 kW due to fluctuations, the controller limits it to the lower power limit of 120 kW. When the demand falls between 120 kW and 180 kW, the controller maintains the original demand and outputs it directly.

[0081] As the vehicle climbs the hill and enters a slight downhill section, the road load decreases, the actual vehicle speed recovers, and both speed deviation and acceleration approach zero. The power variation coefficient obtained from the table automatically decreases, for example, to 0.05. Correspondingly, the theoretical upper and lower limits shrink to 157.5 kW and 142.5 kW, respectively. After motor capacity constraints, the allowable power fluctuation range is further narrowed. At this point, any minute invalid fluctuations in the demand power generated by the PID controller will be filtered out by this narrow constraint, the motor power output curve becomes smooth, and the upward trend of motor winding temperature is effectively suppressed.

[0082] In this scenario, this method ensures that the motor power remains stable while meeting the vehicle speed tracking requirements, avoiding forced power limiting protection triggered by motor temperature exceeding limits due to drastic power fluctuations. Even during high-speed cruising on mountain roads, the vehicle's power output remains strong, preventing sudden speed reductions due to overheating, significantly improving transportation timeliness and driving smoothness. Furthermore, the physical logic of the entire power limiting process encompasses a complete technical chain, from mapping vehicle speed difference and acceleration to power change coefficients, generating theoretical boundaries, correcting motor capabilities, and finally saturation limiting. Each step corresponds to specific measurable physical quantities and explicit control actions.

[0083] As a second aspect of this application, a cruise power control device is also provided. Figure 3 The diagram shown is a schematic of a cruise power control device provided in an embodiment of this application. Figure 3 As shown, the device includes: The speed deviation acquisition module 31 is used to acquire the difference between the target speed and the actual speed of the vehicle to obtain the speed deviation. Acceleration acquisition module 32 is used to acquire the vehicle's acceleration; The fluctuation amplitude determination module 33 is used to determine the allowable power fluctuation amplitude based on the speed deviation and acceleration; The power limiting module 34 is used to dynamically limit the motor power demand during the cruise process according to the allowable power fluctuation range, so as to obtain the actual output motor control power.

[0084] The cruise power control device provided in this application introduces speed deviation and acceleration into the power regulation logic, dynamically generates the allowable power fluctuation range based on the combined state of the two, and limits the motor power demand generated by cruise control using this fluctuation range. When the vehicle's dynamics change significantly, the allowable power fluctuation range is adaptively widened to ensure vehicle speed following capability; when entering steady-state cruise, the range automatically narrows, effectively suppressing drastic fluctuations in motor power. This avoids a sharp rise in motor temperature due to frequent high-power charging and discharging, preventing the triggering of forced power limiting due to high motor temperature, thereby ensuring continuous and stable power output capability of the entire vehicle under cruise conditions.

[0085] As a third aspect of this application, this application also provides an electric vehicle, comprising: Power battery; Drive motor; And the aforementioned cruise power control device.

[0086] Under cruising conditions, the electric vehicle can effectively suppress drastic fluctuations in motor power, reduce motor temperature rise, and avoid forced power limiting through the aforementioned methods and devices, thereby ensuring the continuous and stable power output of the entire vehicle.

[0087] The methods in this application can be implemented, in whole or in part, by software, hardware, firmware, or any combination thereof. When implemented in software, they can be implemented, in whole or in part, as a computer program product. This computer program product includes one or more computer programs or instructions that, when loaded and executed on a computer, perform, in whole or in part, the processes or functions described in this application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, network equipment, user equipment, core network equipment, OAM (Operational Information Management), or other programmable devices.

[0088] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this application. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0089] The computer program or instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium may be any available medium that a computer can access, or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; or an optical medium, such as a digital video optical disc; or a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0090] Furthermore, embodiments of this application may also be storage media storing a computer program, which is executed by a processor of the steps in a cruise power control method described in any of the above embodiments of this specification.

[0091] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, because according to this application, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0092] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For apparatus embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0093] The steps in the methods of the various embodiments of this application can be adjusted, combined, or deleted according to actual needs, and the technical features described in each embodiment can be replaced or combined. The apparatuses in the various embodiments of this application can be combined, divided, or deleted according to actual needs.

[0094] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0095] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software unit executed by a processor, or a combination of both. The software unit can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0096] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0097] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A cruise power control method, characterized in that, The method includes: The difference between the vehicle's target speed and its actual speed is obtained to determine the speed deviation. Obtain the acceleration of the vehicle; The allowable power fluctuation range is determined based on the speed deviation and the acceleration. Based on the allowable power fluctuation range, the motor power demand during cruise is dynamically limited to obtain the actual output motor control power.

2. The cruise power control method according to claim 1, characterized in that, The allowable power fluctuation range is defined by an upper power limit and a lower power limit. The step of dynamically limiting the motor's power demand during cruise based on the allowable power fluctuation range to obtain the actual output motor control power includes: When the motor's required power is greater than or equal to the lower power limit and less than or equal to the upper power limit, the motor control power is determined to be the motor's required power. When the required power of the motor is less than the lower power limit, the control power of the motor is determined to be the lower power limit; When the motor's required power is greater than the upper power limit, the motor's control power is determined to be the upper power limit.

3. The cruise power control method according to claim 1, characterized in that, The step of determining the allowable power fluctuation range based on the speed deviation and the acceleration includes: Based on the speed deviation and the acceleration, the theoretical upper limit and theoretical lower limit of the motor control power are obtained; Obtain the maximum driving power and maximum generating power of the vehicle's motor; The upper limit of power is obtained by comparing the theoretical upper limit with the maximum driving power and maximum generating power of the vehicle motor. The power lower limit is obtained by comparing the theoretical lower limit with the maximum driving power and maximum generating power of the vehicle motor. The allowable power fluctuation range is determined based on the upper power limit and the lower power limit.

4. The cruise power control method according to claim 3, characterized in that, The step of obtaining the theoretical upper limit and theoretical lower limit of the motor control power based on the speed deviation and the acceleration includes: The power change coefficient is obtained based on the speed deviation and the acceleration. Obtain the vehicle's theoretical power requirement; The theoretical upper limit and theoretical lower limit of the motor control power are obtained by calculating the power variation coefficient and the theoretical power requirement.

5. The cruise power control method according to claim 4, characterized in that, The step of obtaining the power change coefficient based on the velocity deviation and the acceleration includes: Obtain a pre-calibrated power change coefficient mapping map, wherein the mapping map is used to characterize the numerical relationship of the power change coefficient corresponding to different combinations of vehicle speed deviation and different acceleration. Based on the speed deviation and the acceleration, the power change coefficient is obtained by querying the mapping diagram.

6. The cruise power control method according to claim 4, characterized in that, The calculation of the power variation coefficient and the theoretical power demand to obtain the theoretical upper limit and theoretical lower limit of the motor control power includes: The fluctuating power is obtained by multiplying the theoretical power demand and the power variation coefficient. The theoretical upper limit is obtained by summing the theoretical required power and the fluctuating power. The difference between the theoretical power demand and the fluctuating power is calculated to obtain the theoretical lower limit value.

7. The cruise power control method according to claim 3, characterized in that, The process of obtaining the upper limit of power by comparing the theoretical upper limit with the maximum driving power and maximum generating power of the vehicle motor includes: When the theoretical upper limit value is greater than or equal to the maximum power generation and less than or equal to the maximum drive power, the power upper limit value is determined to be the theoretical upper limit value; When the theoretical upper limit is less than the maximum power generation, the upper limit of the power generation is determined to be the maximum power generation. When the theoretical upper limit value is greater than the maximum driving power, the upper limit value of the power is determined to be the maximum driving power.

8. The cruise power control method according to claim 3, characterized in that, The process of obtaining the power lower limit by comparing the theoretical lower limit with the maximum driving power and maximum generating power of the vehicle motor includes: When the theoretical lower limit is greater than or equal to the maximum power generation and less than or equal to the maximum drive power, the power lower limit is determined to be the theoretical lower limit. When the theoretical lower limit is less than the maximum power generation, the power lower limit is determined to be the maximum power generation. When the theoretical lower limit is greater than the maximum driving power, the power lower limit is determined to be the maximum driving power.

9. A cruise power control device, characterized in that, include: The speed deviation acquisition module is used to obtain the difference between the vehicle's target speed and actual speed to obtain the speed deviation; An acceleration acquisition module is used to acquire the acceleration of the vehicle; The fluctuation amplitude determination module is used to determine the allowable power fluctuation amplitude based on the speed deviation and the acceleration; The power limiting module is used to dynamically limit the motor power demand during cruise based on the allowable power fluctuation range, so as to obtain the actual output motor control power.

10. An electric vehicle, characterized in that, include: Power battery; Drive motor; And the cruise power control device as described in claim 9 above.

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