Control method and control system for electric truck to park on slope and electric truck

Abstract

The invention relates to a slope parking control method and system for an electric truck and the electric truck. According to the slope parking control method for the electric truck, a motor controller MCU executes the steps, and state information of the truck is obtained; when the slope sliding condition is met, a slope holding mode is executed; in the hill-holding mode, the MCU determines control parameters according to the current gear and the load state so as to realize zero setting of the rotating speed of the motor; the control parameters comprise a P I parameter, a rotating speed slope parameter and a torque slope parameter. When the truck is parked on the slope, different control parameters can be output to adapt to different gears and different loading states of the truck, and smoothness of the truck in the slope parking process is effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric trucks, in particular to a control method and system for hill holding of electric trucks. BACKGROUND

[0002] Electric trucks generally do not have locking mechanisms, and the operation requirements for drivers are high when the vehicle is parked or started on a slope, and the vehicle is prone to rolling down the hill, which is not safe.

[0003] In related technologies, electric trucks have complex working conditions with multiple gears (such as D1 and D2 gears, with significant speed ratio differences) and different load states (such as with or without a trailer). If a fixed control parameter (such as a single speed threshold and unified PI parameter) is used to control the vehicle, it cannot balance the "rolling down the hill speed" and "driving smoothness" under different working conditions, which may lead to excessive rolling distance due to conservative parameters, and vehicle jerk due to aggressive parameters. SUMMARY

[0004] The purpose of the present application is to provide a control method for hill holding of electric trucks, which can output different control parameters to adapt to different gears and different load states of the vehicle when the truck is parked on a hill, and effectively ensure the smoothness of the vehicle during hill holding.

[0005] To achieve the above purpose, according to the first aspect of the present application, the present application provides a control method for hill holding of electric trucks, which is executed by a motor controller MCU, comprising the following steps:

[0006] Obtaining the state information of the vehicle;

[0007] Executing a hill holding mode when the rolling down the hill condition is met; the rolling down the hill condition comprises:

[0008] The brake information is False;

[0009] The current gear is not neutral;

[0010] The motor speed direction is opposite to the VCU instruction speed direction, and the motor speed exceeds the set speed threshold of the current gear;

[0011] The VCU request torque is less than the hill holding required torque;

[0012] In the hill holding mode, the MCU controls the motor speed to zero according to the control parameters determined by the current gear and load state; the control parameters include PI parameters, speed slope parameters and torque slope parameters.

[0013] In some embodiments of the present application, the control method further comprises:

[0014] The single hill-holding duration is not more than a preset duration, and the continuous hill-holding times are not more than a preset number of times.

[0015] The motor is prevented from being blocked for a long time, and heat accumulation caused by multiple hill-holding in a short time is prevented. By limiting the motor blocking time directly through the preset duration and number of times, the risk of overheating is reduced, and the service life of the motor is prolonged.

[0016] In some embodiments of the present application, the preset duration is 5±1 seconds, and the preset number of times is 3±1 times.

[0017] When the brake signal becomes True, the continuous hill-holding time count is cleared.

[0018] In some embodiments of the present application, the set speed threshold is inversely proportional to the gear speed ratio.

[0019] When the gear is D1, the set speed threshold is R1.

[0020] When the gear is D2, the set speed threshold is R2.

[0021] Wherein, R1>R2, and the value of R1 / R2 is close to the value of D1 gear speed ratio / D2 gear speed ratio.

[0022] In some embodiments of the present application, the MCU allows the hill-holding mode to be executed only when it is in the torque control mode, and returns to the torque control mode only after the hill-holding mode is exited.

[0023] When the mode is switched, the initial torque of the current mode inherits the final output torque of the previous mode.

[0024] In some embodiments of the present application, the PI parameters include a proportional coefficient Kp and an integral coefficient Ki.

[0025] The load state includes with hanging and without hanging.

[0026] Under the same gear, the Kp value in the with hanging state is higher than the Kp value in the without hanging state.

[0027] Under the same gear, the Ki value in the with hanging state is higher than the Ki value in the without hanging state.

[0028] In some embodiments of the present application, the MCU determines the control parameters according to the current gear and the load state, including: obtaining the control parameters in the model according to the current gear and the load state; the control parameters in the model are determined based on calibration.

[0029] According to a second aspect of the present application, the present application provides a control system for hill-holding of an electric truck, comprising:

[0030] The acquisition module is configured to acquire state information of the vehicle, wherein the state information comprises brake information, gear information, motor speed direction, motor speed, VCU instruction speed direction, set speed threshold of the current gear, VCU requested torque and required torque for hill holding;

[0031] The execution module is configured to execute the hill holding mode when the hill coasting condition is met, wherein the hill coasting condition comprises:

[0032] The brake information is False;

[0033] The current gear is not neutral gear;

[0034] The motor speed direction is opposite to the VCU instruction speed direction, and the motor speed exceeds the set speed threshold of the current gear;

[0035] The VCU requested torque is less than the required torque for hill holding;

[0036] The determination module is configured to, in the hill holding mode, control the motor speed to be zero by the MCU according to the determined control parameters of the current gear and the load state, wherein the control parameters comprise PI parameters, speed slope parameters and torque slope parameters.

[0037] The motor controller MCU is configured to execute the control method according to any one of claims 1 to 7.

[0038] According to a third aspect of the present application, the present application provides an electric truck comprising the above control system.

[0039] The above technical features have at least the following advantages and beneficial effects:

[0040] In the hill holding mode, the MCU controls the motor speed to be zero according to the determined control parameters of the current gear and the load state, so that different control parameters can be output to adapt to different gears and different load states of the vehicle when the truck is holding the hill, thereby effectively ensuring the smoothness of the vehicle during hill holding.

[0041] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0043] In order to more completely understand the present application and its beneficial effects, the following will be described in conjunction with the drawings, wherein the same reference numerals in the following description represent the same parts.

[0044] Figure 1 is a control flow chart of the electric truck hill holding shown in the embodiment of the present application.

[0045] Figure 2 is a control mode flow chart of the electric truck shown in the embodiment of the present application DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0047] The electric truck generally has no locking mechanism, and the operation requirement of the driver is high when the vehicle is parked or started on a slope, and the vehicle is prone to rolling on the slope, and the safety is poor. In the related art, the hill holding logic is mainly judged by the vehicle control unit (VCU), and then the hill holding instruction or torque instruction is sent to the motor control unit (MCU). The time required for this process from the VCU to complete the rolling judgment, send the instruction to the MCU, and then perform closed-loop regulation is long, resulting in a large rolling distance.

[0048] One of the inventive concepts of the present application is to concentrate the hill holding judgment and control logic in the MCU, and the MCU autonomously judges whether it needs to enter the hill holding state according to the motor speed and other state conditions. The hill holding control can complete the judgment and execution within 2 milliseconds, greatly reducing the response time and rolling distance.

[0049] In the related art, the electric truck has complex working conditions of multiple gears (such as D1 gear, D2 gear, with significant speed ratio difference), different load states (such as with or without a trailer), and the like. If a fixed control parameter (such as a single speed threshold, unified PI parameter) is used to control the vehicle, the “rolling suppression speed” and “driving smoothness” under different working conditions cannot be considered, and the rolling distance may be out of standard due to conservative parameters, and the vehicle may be jerked due to aggressive parameters.

[0050] One of the inventive concepts of the present application is to output different control parameters when the truck is hill holding to adapt to different gears and different load states of the vehicle, effectively ensuring the smoothness during the hill holding process of the vehicle.

[0051] Reference Figure 1 , Figure 1 is a control flow chart of the electric truck hill holding shown in the embodiment of the present application. The embodiment of the present application provides a control method for the electric truck hill holding, which is specifically as follows:

[0052] S110: the following steps are performed by the motor controller MCU:

[0053] S120: Obtain state information of the vehicle.

[0054] The state information includes brake information, gear information, motor speed direction, motor speed, VCU instruction speed direction, set speed threshold of the current gear, VCU request torque, and torque required for hill holding.

[0055] The brake information includes whether the brake is stepped on and whether the handbrake is pulled.

[0056] The gear includes at least neutral gear, reverse gear, parking gear, D1 gear, and D2 gear.

[0057] The set speed threshold of the gear is different based on different gears.

[0058] S130: When the hill rolling condition is met, execute the hill holding mode; the hill rolling condition includes that the brake information is False; the current gear is non-neutral gear; the motor speed direction is opposite to the VCU instruction speed direction, and the motor speed exceeds the set speed threshold of the current gear; and the VCU request torque is less than the torque required for hill holding.

[0059] S140: In the hill holding mode, the MCU controls the parameters according to the current gear and the load state to realize the speed zero of the motor; the control parameters include PI parameters, speed slope parameters, and torque slope parameters.

[0060] The brake information being False represents that the brake is not actively applied, i.e., the brake is not stepped on and the handbrake is not pulled.

[0061] When the conditions of not actively applying the brake, non-neutral gear, the motor speed direction being opposite to the VCU instruction speed direction, the motor speed exceeding the set speed threshold of the current gear, and insufficient request torque are met, the hill holding mode is entered, and the control parameters are dynamically selected according to the real-time gear and the load state to realize the speed zero.

[0062] The set speed threshold in the hill rolling condition refers to the critical speed value corresponding to different gears, which can be realized by adopting a numerical relationship inversely proportional to the gear speed ratio, for example, a higher threshold is set for D1 gear and a lower threshold is set for D2 gear, which avoids false triggering of low-speed ratio gears by matching the speed ratio difference of the transmission system.

[0063] The torque required for hill holding refers to the minimum torque value required to maintain the vehicle stationary, which can be obtained by calculating the vehicle mass, the slope angle, and the transmission parameters, and this feature ensures that the output capability of the power system meets the hill holding requirement.

[0064] The control parameters include proportional integral parameters, speed change rate, and torque change rate, which can be realized by adopting a preset parameter mapping table, and this feature balances the response speed and control stability by matching the power characteristics of different gears and the load inertia difference.

[0065] When the brake is detected to be inactive and the drive gear is engaged, the actual motor speed direction is compared with the VCU instruction direction in real time. If the directions are opposite and the speed exceeds the set threshold of the current gear, the torque demand is combined to determine whether to enter the hill hold mode. According to the speed ratio of the current gear, a corresponding speed threshold is selected, for example, a 280 rpm threshold is used for D1 gear with a speed ratio of 64, and a 70 rpm threshold is used for D2 gear with a speed ratio of 16. After entering the hill hold mode, the control parameter combination is selected according to whether the gear is engaged: a higher proportional coefficient and integral coefficient are used in the engaged condition to improve the response speed and cope with larger inertia; and the control parameter strength is reduced in the non-engaged condition to ensure smoothness. Through speed closed-loop control, the speed converges to zero quickly, and the torque change slope is constrained to prevent output mutation.

[0066] The hill hold judgment and control function are integrated into the motor controller MCU, eliminating communication delay across units, and shortening the response time from hundreds of milliseconds to milliseconds. By establishing an inverse proportional relationship between the gear speed ratio and the speed threshold, precise triggering in different transmission conditions is achieved. The introduction of a load state parameter matching mechanism enables automatic switching of control strategies under the same gear, solving the fundamental problem that fixed parameters cannot adapt to load changes.

[0067] By dynamically adjusting the control parameters, the hill hold requirements of the electric truck under different working conditions can be better met. This method takes into account the gear and load state of the vehicle, and can provide optimal hill hold performance in various situations, ensuring both the effectiveness of hill hold and the driving experience.

[0068] The application realizes adaptive hill hold control under complex conditions, and can control the hill rolling distance to within 0.3 meters in the D1 gear with the gear engaged, while keeping the torque change rate below 1 Nm / ms, balancing safety and comfort. The differentiated threshold setting for multiple gears reduces the false trigger rate to below 5%, and the dynamic parameter adjustment mechanism makes the speed convergence time difference under different load states less than 0.2 seconds.

[0069] In some embodiments, the control method further includes that the duration of a single hill hold does not exceed a preset duration, and the number of consecutive hill holds does not exceed a preset number.

[0070] The duration of a single hill hold refers to the maximum time limit from entering the hill hold mode to automatically exiting, which can be implemented by setting a timer. When the hill hold duration reaches the preset duration, the hill hold operation is automatically terminated. This feature reduces the risk of overheating by limiting the motor stall time.

[0071] The number of consecutive hill holds refers to the maximum number of times that the hill hold mode can be entered repeatedly, which can be implemented by setting a counter. When the number of consecutive triggers exceeds the preset number, it is prohibited from entering again. By limiting the duration and number of hill holds, heat accumulation is prevented.

[0072] When the vehicle enters the hill hold mode, the hill hold duration is monitored in real time, for example, when the duration reaches 5 seconds, the control mode is automatically switched back to the torque control mode. At the same time, the number of hill hold triggers is recorded, for example, when the number of consecutive triggers reaches 3 times, the hill hold function is temporarily locked. When the driver actively operates the brake or hand brake, the count is cleared and the hill hold permission is restored. This mechanism strictly limits the working time of the motor in the continuous blocking condition, while retaining the ability of the driver to restart the hill hold function in specific scenarios.

[0073] In the related art, the hill hold control does not set the hill hold duration and number of times limit, when the vehicle is in the slope working condition for a long time, the motor may cause the temperature to rise sharply due to continuous blocking. The present scheme actively limits the energy consumption and heat generation of the motor under the premise of ensuring the effectiveness of the hill hold function, and realizes the balance between hill hold demand and thermal management through the preset time and number of times threshold.

[0074] The present application effectively solves the overheating problem of the motor in the frequent hill hold working condition, prolongs the service life of the motor. By presetting the hill hold duration and number of times, the heat generated by the motor blocking is controlled within a safe range, avoiding performance degradation or component damage due to overheating. At the same time, the number zero mechanism is designed to be linked with the driver's operation, so that the hill hold function can provide necessary hill hold support in scenarios such as port loading and unloading, and frequent start-stop on slopes, and can also avoid affecting the operation efficiency due to system lock.

[0075] In some embodiments, the preset duration is 5±1 seconds, and the preset number of times is 3±1 times; when the brake signal becomes True, the number of consecutive hill hold times is cleared.

[0076] The number of times of triggering the brake signal (depressing the brake or pulling up the hand brake) is cleared, taking into account the safety of the motor and the flexibility of driving - the driver can restore the hill hold permission after active operation, which is suitable for frequent start-stop scenarios (such as port loading and unloading).

[0077] The brake signal becoming True specifically refers to the driver actively depressing the brake or pulling up the hand brake. By clearing the hill hold count when the driver actively depresses the brake or pulls up the hand brake, more hill hold opportunities can be provided to the driver while ensuring the safety of the motor. This design not only considers the safety of the motor, but also improves the practicality and flexibility of the hill hold function, so that the system can better adapt to complex driving scenarios.

[0078] When the brake condition is not met, i.e. the driver steps on the brake or pulls up the hand brake, the system will enter the hill hold count zero. For example, the vehicle has been using the automatic hill hold function on the slope for 3 times, the system no longer automatically enters the hill hold mode. At this time, if the driver steps on the brake pedal or pulls up the hand brake, the system will reset the hill hold count to 0. In this way, when the driver needs to use the hill hold function again, the system can provide 3 opportunities for automatic hill holding, increasing the availability of the hill hold function.

[0079] In some embodiments, the threshold speed is set inversely proportional to the gear speed ratio; when the gear is D1, the threshold speed is set to R1; when the gear is D2, the threshold speed is set to R2; R1>R2, and the value of R1 / R2 is close to the value of D1 gear speed ratio / D2 gear speed ratio.

[0080] For example, the D1 gear sets the speed threshold: 250-300 rpm. The D2 gear sets the speed threshold: 60-80 rpm. Specifically, when the D1 gear ratio is 64, the threshold speed is set to 280 rpm; when the D2 gear ratio is 16, the threshold speed is set to 70 rpm. At this time, the speed ratio ratio is 4, and the threshold ratio is also 4. This correspondence makes the hill hold judgment adapt to the transmission characteristics of different gears, avoiding misjudgment caused by speed ratio difference. When the motor speed direction is opposite to the instruction direction, if the actual speed exceeds the set speed threshold corresponding to the current gear, it is accurately identified as a real coasting state.

[0081] In the related art, using a fixed speed threshold cannot adapt to the speed ratio difference of multi-gear vehicles, which is easy to miss the judgment at low speed ratio gears due to high threshold, or misjudge at high speed ratio gears due to low threshold. The present scheme establishes an inverse relationship between speed ratio and threshold, so that the sensitivity of hill hold judgment matches the transmission characteristics of each gear, effectively eliminating the influence of speed ratio difference on judgment accuracy.

[0082] Through the above technical scheme, accurate identification of the coasting state under different gears is realized, which avoids false triggering while ensuring the response speed of hill hold. A higher threshold is used at high speed ratio gears to filter speed fluctuations in normal driving, and a lower threshold is used at low speed ratio gears to capture small coasting trends in time. This dynamic adjustment mechanism makes the hill hold control adapt to the high torque output characteristics of D1 gear with large speed ratio, and matches the low speed running state of D2 gear with small speed ratio, significantly improving the adaptability of hill hold control of multi-gear vehicles.

[0083] Referring to Figure 2 , Figure 2 is the control mode flowchart of the electric truck shown in the embodiments of the present application. In Figure 2The middle MCU only allows the hill hold mode to be executed when in the torque control mode, and only returns to the torque control mode after the hill hold mode is exited; the initial torque of the current mode is inherited from the final output torque of the previous mode when the mode is switched.

[0084] The torque control mode refers to a control mode in which the motor controller outputs power by receiving a torque instruction sent by a vehicle control unit, and serves as a basic control state of the hill hold mode, and can provide stable power output conditions. The hill hold mode refers to a control mode in which the motor speed is adjusted to zero, and the hill hold mode is exited by dynamically adjusting the torque output to suppress the hill rolling. The initial torque inheritance refers to a function of adopting data latching or state memory to inherit the actual output torque at the end of a control period of a previous control mode as an initial torque of a new mode, and the function is used to eliminate torque step changes in the mode switching process.

[0085] The torque control mode provides a stable power basis for the hill hold mode, and avoids instability caused by switching from other modes. After the hill hold mode is exited, only the torque control mode is returned, and disorderly switching to other modes is avoided.

[0086] When the mode is switched, the initial torque of the current mode is inherited from the final output torque of the previous mode (for example, when the hill hold mode is exited, the initial torque of the torque control mode = the final hill hold torque of the hill hold mode), and the torque sudden change is avoided to cause the vehicle to jerk, and smooth transition between control modes is achieved.

[0087] In some embodiments, the application further proposes a control method for hill holding of an electric truck, the PI parameters include a proportional coefficient Kp and an integral coefficient Ki, and the load state includes with a trailer and without a trailer. In the same gear, the Kp value in the with-trailer state is higher than the Kp value in the without-trailer state; in the same gear, the Ki value in the with-trailer state is higher than the Ki value in the without-trailer state.

[0088] The proportional coefficient Kp refers to a linear relationship coefficient between a speed deviation and an output torque, and can be implemented by using proportional coefficients in different numerical ranges, for example, a higher Kp value is used in the with-trailer state to speed up the system response. The integral coefficient Ki refers to an integral relationship coefficient between a speed deviation accumulation and an output torque, for example, a larger Ki value is used in the with-trailer state to eliminate the steady-state error. The load state is determined by a vehicle trailer connection signal or a weight sensor signal.

[0089] The core parameters of the PI controller (proportional-integral controller) are indeed the proportional coefficient (Kp) and the integral coefficient (Ki).

[0090] The output formula of the PI controller is:

[0091] Output = Kp * current error + Ki * ∫(error) dt;

[0092] Where: current error = set value - current measured value

[0093] ∫(error)dt = integral of error from time 0 to now (i.e. area under the error curve).

[0094] When the vehicle is in the towing state, due to the increase in inertia caused by the additional mass of the trailer, stronger torque response capability is needed to suppress hill rolling. At this time, the control system automatically switches to higher proportional and integral coefficients, for example, in D1 gear with trailer, the Kp value can be set to 1.3 times that of the non-towing state, and the Ki value is set to 1.2 times that of the non-towing state. This parameter adjustment enables the motor controller to respond more quickly to speed deviation, while maintaining control stability and shortening the adjustment time. For the light load state without towing, a relatively low PI parameter combination is used, for example, in D2 gear without towing, the Kp value is reduced by about 30% compared to the towing state, and the Ki value is reduced by about 25%, thereby avoiding torque mutation caused by overly sensitive control.

[0095] In related technologies, the hill hold control method uses fixed PI parameters, which cannot distinguish between the load differences of vehicles with or without trailers. For example, a certain type of heavy truck uses the same control parameters when empty and when fully loaded, resulting in excessive torque adjustment and vehicle shaking when empty, and insufficient response and excessive hill rolling distance when fully loaded. By establishing a dynamic mapping relationship between the load state and the PI parameters, the technical contradiction that a single parameter cannot adapt to different load characteristics is solved.

[0096] Through the above technical solutions, load state adaptive hill hold control is achieved, which enhances the dynamic response capability of the control system in the towing heavy load working condition, effectively shortens the hill rolling distance, and reduces the control sensitivity in the non-towing light load working condition, avoiding vehicle body vibration caused by torque step changes. This parameter dynamic adjustment mechanism takes into account the control performance requirements under different load states, ensuring hill hold safety while improving driving smoothness.

[0097] In some embodiments, the MCU determines the control parameters according to the current gear and the load state, including deriving the control parameters in the model according to the current gear and the load state, and the control parameters in the model are determined based on calibration.

[0098] The current gear position refers to the current transmission ratio state of the vehicle, which can be represented by D1 gear, D2 gear and other non-empty gear position information. Different gears correspond to different speed ratios and torque output characteristics. The load state refers to whether the vehicle is connected to a trailer, which can be identified by a vehicle-mounted sensor or trailer connection signal. The connected state and the unconnected state have significant differences in vehicle inertia and power demand. The model refers to the pre-set parameter mapping relationship, which can be implemented by a two-dimensional table or a function relationship. The control parameters are obtained by combining the gear position and the load state. Calibration determination refers to testing and optimizing parameters through vehicle tests. The parameters can be adjusted according to the hill-hold time, hill-hold distance and driving smoothness index in different working conditions.

[0099] When the vehicle enters the hill-hold mode, the MCU calls the corresponding control parameter combination from the pre-stored parameter model according to the current gear signal and the trailer connection state. For example, when the vehicle is detected to be in D1 gear and connected to a trailer, the model outputs PI parameters, speed slope parameters and torque slope parameters suitable for high-speed ratio and large inertia conditions. When the vehicle is in D2 gear and not connected to a trailer, the model outputs parameter combinations suitable for low-speed ratio and small inertia conditions. These parameters are pre-determined through calibration tests, which consider the speed response characteristics under different gear ratios and the influence of the connected state on the vehicle inertia to ensure that the parameter combination can accurately match the actual working condition requirements.

[0100] The parameter model established through calibration can dynamically match the optimal parameters according to the real-time working conditions, solving the problem of insufficient adaptability of fixed parameters.

[0101] In some embodiments, the load state can also include the weight of the load, and different control parameters are output based on different load weights.

[0102] In related technologies, the hill-hold method sets a hill-hold time limit and a repeated entry limit, but this fixed limit may not meet the needs of long-time frequent start-stop working conditions. In this case, if the hill-hold time or the number of repetitions is simply increased, it may cause the motor temperature to be too high, affecting its performance and service life. On the other hand, if the hill-hold operation is too conservative, it may affect the normal operation efficiency of the vehicle.

[0103] One concept of the present application is that the control method further includes real-time monitoring of the motor temperature and dynamically adjusting the hill-hold parameters according to the temperature. When the temperature exceeds the limit, the light hill-hold mode is switched.

[0104] Real-time monitoring of the motor temperature refers to collecting temperature data of the motor during operation through a temperature sensor. Specifically, a thermocouple or a thermistor can be used to realize real-time acquisition of the thermal state information of the motor.

[0105] The motor controller continuously collects temperature signals. When the temperature is within the normal range, the hill hold parameters remain at the calibrated values to achieve optimal control effect. As the temperature rises, the hill hold duration is gradually shortened, for example, from 5 seconds to 3 seconds, and the torque slope parameter is reduced to slow down heat accumulation. If the temperature reaches the preset warning value, switch to the light hill hold mode, at this time the motor output torque is reduced to 60%-80% of the calibrated value, and the speed is allowed to fluctuate within ±10 rpm, thereby reducing the locked-rotor time. When the temperature falls back to the safe range, the system automatically restores the normal hill hold parameters.

[0106] Through temperature monitoring and dynamic adjustment of parameters, the thermal load is actively managed under the premise of ensuring the hill hold function, avoiding the control rigidity problem caused by fixed threshold. The cooperative management of motor thermal state and hill hold control is realized, which not only prevents motor overheating damage, but also prolongs the available time of hill hold function. In the scene of frequent start-stop such as port loading and mine climbing, the system can adaptively adjust the control strength according to the temperature change, avoid the operation interruption caused by completely disabling the hill hold function due to overheating protection, and maintain the basic vehicle control ability through the light hill hold mode.

[0107] In some embodiments, the control method further comprises real-time monitoring of the motor temperature and dynamically adjusting the hill hold parameters:

[0108] When the temperature is < T1, the single hill hold duration is extended to 7 seconds; when the temperature is > T2: the single hill hold duration is shortened to 3 seconds; where T1 < T2.

[0109] When the temperature is > T3, switch to the light hill hold mode, allowing 1-3 km / h controlled coasting; the control parameters of the light hill hold mode are 30-50% of the normal mode. Hill hold mode switching: introduce a "light hill hold" mode. When the motor temperature approaches the critical value, instead of completely disabling the hill hold function, switch to a "light hill hold" mode that consumes less energy. In this mode, slight coasting is allowed (such as allowing the vehicle to move slowly within a controllable range), but basic control of the vehicle is still maintained.

[0110] Based on historical temperature data and current working conditions, a simple temperature prediction model is established. This model can predict the trend of motor temperature under the current use mode, so as to adjust the control parameters in advance.

[0111] When the motor temperature is detected to continue to rise, the MCU can actively control the vehicle cooling system to increase the heat dissipation of the motor. For example, increase the cooling liquid circulation speed or start the auxiliary fan.

[0112] Embodiments of the present application also propose a control system for electric truck hill hold, comprising:

[0113] The acquisition module is configured to acquire state information of the vehicle, and the state information includes brake information, gear information, motor speed direction, motor speed, VCU instruction speed direction, set speed threshold of real-time gear, VCU request torque, and torque required for hill holding.

[0114] The execution module is configured to execute the hill holding mode when the hill coasting condition is met, and the hill coasting condition includes that the brake information is False, the real-time gear is a non-parking gear, the motor speed direction is opposite to the VCU instruction speed direction, the motor speed exceeds the set speed threshold of the real-time gear, and the VCU request torque is less than the torque required for hill holding.

[0115] The determination module is configured to determine a control parameter according to the real-time gear and the load state to realize speed zero of the motor in the hill holding mode, and the control parameter includes a PI parameter, a speed slope parameter, and a torque slope parameter.

[0116] The motor controller MCU is configured to execute a specific control method.

[0117] The acquisition module refers to a hardware or software unit for real-time acquisition of vehicle operation data, and can be specifically realized by cooperation of a CAN bus communication module and a sensor, for example, the motor speed is acquired by a wheel speed sensor, and the gear information is acquired by VCU message analysis. The execution module refers to a logic judgment and mode switching unit, and can be specifically realized by a state machine algorithm in the MCU, for example, the hill holding mode is triggered based on a preset condition. The determination module refers to a parameter dynamic adjustment unit.

[0118] When the vehicle is on a slope, the acquisition module continuously monitors the brake state, the gear signal, and the motor speed, and the execution module triggers the hill holding mode by judging the conditions of inactive brake, non-parking gear state, abnormal motor speed direction exceeding a threshold, insufficient power, and the like. The determination module matches a corresponding PI control parameter combination from a pre-stored parameter library according to the current gear ratio and the load state with or without a hitch, and simultaneously loads the slope limitation parameters of the speed and the torque. For example, in the D1 gear without hitch condition, a higher proportional coefficient and integral coefficient are adopted, and a steep speed drop slope is matched, so that the motor completes the speed zero control within 2 milliseconds.

[0119] In some specific embodiments, the acquisition module can integrate temperature sensor data for thermal protection decision, the execution module can include a timer unit to limit the duration of single hill holding, and the parameter library of the determination module can be established by vehicle calibration test, for example, the torque slope parameter is calibrated to be 50 Nm / ms for the D1 gear with hitch condition.

[0120] Specifically, when the vehicle is on a slope, the acquisition module continuously collects brake status, gear information, and motor operating data. The execution module compares the real-time data with the preset conditions. When it is detected that the brake is not pressed, the gear is not in neutral, the actual motor speed direction is opposite to the VCU instruction direction, and the VCU output torque is insufficient to maintain the vehicle stationary, the hill hold control mode is immediately activated. The determination module selects corresponding proportional integral coefficient, speed regulation rate limit value, and torque adjustment rate limit value from the preset parameter library according to the current gear state and whether the vehicle is towing goods. The control system implements closed-loop control on the motor based on the selected parameters, so that the actual speed quickly returns to zero and maintains a stable state.

[0121] Through the above technical solution, the hill hold control problem of the multi-gear electric truck under complex working conditions is solved. The system can automatically adjust the speed judgment threshold according to the speed ratio difference to avoid false triggering at low gears. Through the identification of the towing state and the dynamic switching of parameters, the hill hold efficiency is ensured while the torque fluctuation is reduced. The control system significantly shortens the response time of hill start judgment and execution, improves the driving smoothness under the premise of safety, and meets the needs of different operation scenes such as port loading and unloading and mountain transportation.

[0122] In some embodiments of the present application, the electric truck includes the control system.

[0123] In a specific embodiment, the electric truck is currently in D1 gear (speed ratio of 64) when driving. The driver releases the accelerator pedal, and the vehicle starts to have a slight tendency to roll down the hill. At this time:

[0124] The MCU detects the following states: the brake signal is False (the driver does not press the brake); the current gear is not in neutral; the motor speed is opposite to the VCU instruction direction, and is greater than 280 rpm (the threshold value of D1 gear); and the VCU request torque is less than the hill hold required torque.

[0125] The MCU determines that all conditions for entering the hill hold mode are met, and immediately switches the control mode from torque control to 0 speed control. After entering the hill hold mode, the MCU selects the control parameters preset for D1 gear and the no-towing state, including specific PI parameters, speed and torque response slope parameters. The MCU performs speed zero control to prevent the vehicle from continuing to roll down the hill.

[0126] The hill hold mode duration timer starts, and when it reaches 5 seconds or the driver steps on the accelerator pedal (the VCU request torque increases), the MCU automatically exits the hill hold mode and returns to the torque control mode. If the driver appears to roll down the hill again within a short time, the MCU can enter the hill hold mode again, up to 3 times.

[0127] In this way, the electric truck can realize fast and smooth hill holding on the slope, greatly reduce the distance of coasting down the slope, and ensure good driving experience.

[0128] In the description of the present application, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0129] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0130] The embodiments, implementation manners and related technical features of the present application can be combined or replaced with each other without conflict.

[0131] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification made to the above embodiment without departing from the technical solution of the present application and in accordance with the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A control method for an electric truck to stay on a slope, characterized in that: The motor controller MCU performs the following steps: Get vehicle status information; The hold-on-slope mode is executed when the slope sliding conditions are met; the slope sliding conditions include: Braking information is False; The current gear is not neutral; The motor speed direction is opposite to the VCU command speed direction, and the motor speed exceeds the set speed threshold of the current gear; The VCU requested torque is less than the torque required for holding on a hill; In hill-holding mode, the MCU determines control parameters based on the current gear position and load status to achieve zero speed adjustment of the motor; the control parameters include PI parameters, speed slope parameters and torque slope parameters.

2. The control method according to claim 1, characterized in that: The control method further includes: The duration of a single hill-holding period shall not exceed the preset duration, and the number of consecutive hill-holding periods shall not exceed the preset number. Prevents prolonged motor stalls and heat buildup caused by repeated ramping in a short period of time. By presetting the duration and frequency limits, you can directly limit the motor stall time, reduce the risk of overheating, and extend the motor's service life.

3. The control method according to claim 2, wherein: The preset duration is 5±1 seconds, and the preset number of times is 3±1 times; When the brake signal becomes True, the count of consecutive hill-holding times is cleared.

4. The control method according to claim 1, wherein: The set speed threshold is inversely proportional to the gear ratio; When the gear is D1, set the speed threshold to R1; When the gear is D2, set the speed threshold to R2; Among them, R1>R2, and the value of R1 / R2 is close to the value of D1 gear ratio / D2 gear ratio.

5. The control method according to claim 1, wherein: The MCU is only allowed to execute the hill-holding mode when in the torque control mode, and will only return to the torque control mode after exiting the hill-holding mode; When switching modes, the initial torque of the current mode inherits the final output torque of the previous mode.

6. The control method according to claim 1, wherein: The PI parameters include a proportional coefficient Kp and an integral coefficient Ki; The load state includes with or without a hook; At the same gear, the Kp value with the gear engaged is higher than that without the gear engaged. In the same gear, the Ki value with the gear engaged is higher than that without the gear engaged.

7. The control method according to claim 1, wherein: The MCU determines the control parameters based on the current gear position and load status, including: According to the current gear position and load state, control parameters are derived in the model; the control parameters in the model are determined based on calibration.

8. A control system for an electric truck holding a hill, characterized in that: include: An acquisition module is used to obtain vehicle status information; the status information includes brake information, gear information, motor speed direction, motor speed, VCU command speed direction, set speed threshold of the current gear, VCU requested torque, and torque required for holding on a hill; An execution module is used to execute the hold-on-slope mode when a slope slipping condition is met; the slope slipping condition includes: Braking information is False; The current gear is not neutral; The motor speed direction is opposite to the VCU command speed direction, and the motor speed exceeds the set speed threshold of the current gear; The VCU requested torque is less than the torque required for holding on a hill; A determination module is used for determining control parameters based on the current gear position and load state of the MCU in the hill-holding mode to achieve zero speed adjustment of the motor; the control parameters include PI parameters, speed slope parameters, and torque slope parameters; A motor controller MCU, configured to execute the control method according to any one of claims 1 to 7.

9. An electric truck, characterized in that: Includes the control system described in claim 8.

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