Control system for torque limited vehicle

Abstract

Aspects of the present disclosure relate to a control system (100) for controlling at least one electric traction motor (312, 314) of a torque limited vehicle, where the at least one electric traction motor has a torque limit (602). The control system is configured to: receive an indication of an external condition in which the vehicle is operating; determining whether the external condition is an additional torque demand condition; and outputting a torque limit forced takeover signal (156) if the external condition is an additional torque demand condition. When the vehicle is operating in certain external conditions, the torque limit forced take-over signal allows selective provision of additional torque.

Description

Technical Field

[0001] This disclosure relates to control systems for torque-limited vehicles. Aspects of the invention relate to control systems, systems, vehicles, methods, and computer-readable instructions. Background Technology

[0002] Torque limiting is known for its application to vehicles. This torque limiting restricts the amount of torque output available to a particular vehicle or operator. For example, imposing a torque limit can provide a smoother driving experience or improved fuel economy by offering an extended range for a given battery capacity. Limiting the torque available to inexperienced drivers and / or rental vehicles can also be useful. This can be achieved by imposing a torque limit on one or more of the vehicle's electric traction motors, restricting the available torque to below the maximum torque capacity of those motors. However, it has been found that limiting available torque can lead to underperformance or undesirable vehicle behavior under high torque-demand driving conditions—that is, under conditions requiring additional torque, such as when attempting to accelerate on a steep incline, when towing a trailer, or when driving on soft terrain such as mud, snow, or sand.

[0003] The purpose of this invention is to address one or more of the defects associated with the prior art. Summary of the Invention

[0004] Various aspects and embodiments of the present invention provide a control system, system, vehicle, method for controlling at least one electric traction motor of a torque-limited vehicle as claimed in the appended claims, and computer-readable instructions.

[0005] According to one aspect of the invention, a control system for controlling at least one electric traction motor of a torque-limited vehicle is provided. The control system includes one or more processors configured to: receive an indication of an external condition in which the vehicle is operating; determine whether the external condition is an additional torque demand condition; and, based on the determination that the external condition is an additional torque demand condition, output a torque-limiting override signal.

[0006] According to one aspect of the invention, a control system is provided for controlling at least one electric traction motor of a torque-limited vehicle, wherein the at least one electric traction motor has torque limitation. The control system includes one or more processors configured to: receive an indication of an external condition in which the vehicle is operating; determine whether the external condition is an additional torque demand condition; and, based on the determination that the external condition is an additional torque demand condition, output a torque limitation forced takeover signal.

[0007] By utilizing the control system that requires protection, torque limiting can be selectively and forcibly taken over based on external conditions of vehicle operation. This allows the advantage of torque limiting to be obtained during normal driving, while also allowing additional torque to be provided under conditions requiring additional torque.

[0008] The control system includes one or more controllers, which collectively include: at least one electronic processor having an electrical input for receiving input signals; and at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions on the at least one memory device to: receive an indication of an external condition in which the vehicle is operating; determine whether the external condition is an additional torque demand condition; and output a torque limit forced takeover signal based on the determination that the external condition is an additional torque demand condition.

[0009] As used herein, the term "external condition" refers to one or more factors outside the vehicle that affect its performance. These factors increase drag on the vehicle's acceleration and thus increase the torque output required for a given vehicle acceleration.

[0010] As used herein, the term "additional torque demand condition" refers to one or more predetermined conditions in which the resistance to acceleration of the vehicle is greater than that under normal driving conditions, requiring additional torque at the wheels to overcome this resistance and maintain performance. For example, an additional torque demand condition could be a set of conditions in which the torque at the wheels must be increased by at least 500 Nm, 1000 Nm, 1500 Nm, or 2000 Nm to provide performance comparable to that under typical conditions, such as driving a vehicle with a single occupant on a flat surface.

[0011] Optionally, the indication of external conditions includes one or more of the following: a slope signal indicating the slope of the surface on which the vehicle is supported; a traction signal indicating the presence or absence of a vehicle trailer attached to the vehicle; and a terrain signal indicating the type of terrain on which the vehicle is supported. In such an implementation, an external condition is an additional torque demand condition if: the slope is greater than a slope threshold; the traction signal indicates the presence of a vehicle trailer attached to the vehicle; and / or the terrain signal indicates that the type of terrain is additional torque terrain. These signals provide the control system with a well-defined set of external conditions where it may be necessary to increase the available torque output above the torque limit. An additional torque demand condition may require only a single condition from the applicable conditions for the control system to determine that the external condition is an additional torque condition. Alternatively, an additional torque demand condition may require multiple conditions to be applied for the control system to determine that the external condition is an additional torque condition.

[0012] The slope signal can be a direct measurement of the slope from one or more sensors on the vehicle, such as one or more inclinometers. Alternatively or additionally, the slope signal can be derived from one or more other signals or measurements, such as vehicle speed signals and / or acceleration signals. In one example, the control system receives a longitudinal acceleration signal from an accelerometer (e.g., an accelerometer that forms part of the vehicle's constraint control system) and a vehicle speed signal from a speed sensor (e.g., an ABS sensor or a motor speed sensor), and calculates a linear acceleration based on these signals. The control system then subtracts the linear acceleration from the longitudinal acceleration to determine the acceleration due to gravity, thereby estimating the slope of the surface on which the vehicle is traveling. The slope threshold can be any suitable inclination value. The slope threshold can be selected based on one or more of the following: vehicle characteristics, vehicle operating mode, powertrain characteristics, and driver characteristics. For example, the slope threshold can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25% or higher.

[0013] Towing signals can be received or derived from the output of any suitable one or more devices on the vehicle. For example, a tow hook sensor or network controller indicates when electrical equipment is inserted into the electrical connector on the tow hook, and / or indicates when the driver selects a towing procedure via an input device (such as an infotainment system).

[0014] Terrain signals can be received or derived from the output of any suitable device or one device on the vehicle. For example, they can be received or derived from a terrain mode selector. In such an example, the terrain mode selector can be configured to allow the driver to manually select a terrain mode (e.g., a soft ground driving mode) and / or to automatically detect and select a terrain mode based on one or more sensors (e.g., suspension ride sensors) and / or cameras associated with the vehicle.

[0015] As used herein, the term "additional torque terrain" refers to a surface that requires more torque than a standard road surface for vehicle rolling. In other words, it is a surface with higher rolling resistance than a standard road surface. Additional torque terrain can include, but is not limited to, loose terrain, soft terrain, and / or rugged terrain. Example terrain can include gravel, sand, snow, mud, and / or water.

[0016] Alternatively or additionally, the indication of external conditions may include an indication of torque demand and an indication of the vehicle's actual acceleration, wherein one or more processors are jointly configured to: determine the expected acceleration of the vehicle based on the torque demand, and compare the expected acceleration with the actual acceleration. The external condition may be an additional torque demand condition if the expected acceleration exceeds the actual acceleration by at least a threshold amount. In this way, the control system can determine that the external condition is an additional torque demand condition using signals that have already been ensured to be functionally safe.

[0017] The indication of actual acceleration can be achieved in any suitable manner. For example, the indication can be based on a signal from an accelerometer mounted on or within the vehicle. The indication can be derived by the control system from a vehicle speed signal. This vehicle speed signal can include signals derived from measurements by speed sensors, such as wheel speed sensors or motor rotation speed sensors. The indication of the vehicle's actual acceleration can be received directly from the sensor by the control system, or from one or more other processors in the vehicle that have already derived the vehicle speed and / or acceleration and output it to the control system.

[0018] Optionally, the one or more processors are collectively configured to: receive a rotational speed signal indicating the motor rotational speed of the at least one electric traction motor, and determine the actual acceleration based on the motor rotational speed. In such an implementation, the indication of the actual acceleration is provided by the rotational speed signal. When the driver requires increased torque, for example, with heavy application of the accelerator pedal, there may be a delay between the demand and the change in vehicle speed. By deriving the vehicle acceleration from the motor rotational speed, this delay can be reduced, allowing the control system to react more quickly and permitting increased torque beyond torque limits when needed. It also avoids over-triggered logic due to the difference between the actual and expected acceleration caused by this delay.

[0019] Torque limit mandatory takeover signals may include instructions to temporarily ignore or cancel torque limit.

[0020] Optionally, the torque limit forced takeover signal includes a modified torque limit signal that defines a further torque limit above the torque limit. This further torque limit can be equal to or less than the maximum torque capability of the at least one electric traction motor. In this way, the at least one electric traction motor will be able to be operated to provide a torque output greater than the torque limit but not greater than the further torque limit. This allows the torque output to be increased, but only within a defined range.

[0021] The one or more processors may be configured to apply a modified torque limiting signal to apply a further torque limit instantaneously (i.e., with a step change from the torque limit to a further torque limit).

[0022] Optionally, the one or more processors are collectively configured to: adjust a modified torque limit signal to define a modified torque limit value, which gradually increases from a torque limit to a further torque limit. The one or more processors may be collectively configured to: adjust a modified torque limit signal to define a modified torque limit value, which gradually decreases from a further torque limit to a torque limit. The one or more processors may be collectively configured to: adjust a modified torque limit signal to define a modified torque limit value, which gradually increases from a torque limit to a further torque limit and gradually decreases from a further torque limit to a torque limit. This allows for a smoother delivery of additional torque.

[0023] The one or more processors may be configured to adjust the modified torque limit signal to gradually increase the modified torque limit value from the torque limit to a further torque limit at a substantially constant ramp rate.

[0024] Optionally, the one or more processors are collectively configured to adjust the modified torque limit signal to gradually increase the modified torque limit value from a torque limit to a further torque limit at an ramp rate that varies according to one or more vehicle operating parameters. This allows the speed of implementation to vary for different situations, such as allowing for a faster torque limit increase when needed, or a slower torque limit increase when rapid changes in torque output might be detrimental to the driving experience.

[0025] The one or more processors may be collectively configured to: adjust a modified torque limit signal to increase the modified torque limit value at an ramp rate selected based on a comparison between the torque limit and the torque generated by the powertrain when the external condition is determined to be an additional torque demand condition. For example, the one or more processors may be collectively configured to: receive a torque output signal indicating the torque generated by the at least one electric traction motor when the external condition is determined to be an additional torque demand condition; compare the generated torque with the torque limit; and adjust the modified torque limit signal based on the comparison between the generated torque and the torque limit. In such an example, the modified torque limit signal may be adjusted to define a modified torque limit value that increases at a ramp rate varying according to the difference between the generated torque and the torque limit. For example, when the generated torque equals the torque limit, the ramp rate may be set to a slow rate, and as the difference between the generated torque and the torque limit increases, the ramp rate may be set to an increasingly faster rate. This can reduce the extent to which the driver may feel a sudden increase in available torque when the torque output is already at or near the torque limit when the torque limit is forcibly taken over.

[0026] Optionally, the one or more processors are collectively configured to: upon determining that the external condition is an additional torque demand condition, receive a torque output signal indicating the torque generated by the at least one electric traction motor; compare the generated torque with a torque limit; and, in response to the comparison, adjust a modified torque limit signal to increase the modified torque limit value at a first ramp rate if the generated torque is less than the torque limit, and to increase the modified torque limit value at a second ramp rate slower than the first ramp rate if the generated torque is the same as the torque limit. This provides direct control logic to mitigate the degree to which the driver may perceive a sudden increase in available torque when the torque output is already at the torque limit when the torque limit is forcibly taken over.

[0027] Optionally, the one or more processors are collectively configured to: monitor whether external conditions remain in an additional torque demand condition; and restore the torque limit in response to determining that the external conditions are no longer an additional torque demand condition. For example, the torque limit can be set by stopping the output of the torque limit forced takeover signal in response to determining that the external conditions are no longer an enhanced torque demand condition. In such an example, the torque limit can be restored instantaneously. Alternatively or additionally, the one or more processors can be collectively configured to: adjust the modified torque limit signal to gradually reduce the modified torque limit value from a further torque limit to the torque limit at a descent rate. The descent rate can vary based on one or more vehicle operating parameters (e.g., vehicle speed).

[0028] The modified torque limit signal can be adjusted independently of vehicle speed.

[0029] The one or more processors may be configured to: receive an indication of vehicle speed; compare the vehicle speed with a characteristic speed threshold; and adjust a modified torque limit signal based on the comparison.

[0030] Optionally, the one or more processors are collectively configured to: receive an indication of vehicle speed; compare the vehicle speed with a characteristic speed threshold; and, in response to determining that the vehicle speed exceeds the characteristic speed threshold, adjust a modified torque limit signal according to the vehicle speed to gradually reduce the modified torque limit value from a further torque limit to a torque limit. This adjustment can be performed independently of any monitoring of whether external conditions remain in a state of additional torque demand. In this way, at lower vehicle speeds, the forced take-off of the torque limit can occur to a greater extent when additional torque is most desired, and / or at higher vehicle speeds, the forced take-off of the torque limit can be gradually blended out. The characteristic speed threshold can be any suitable value. For example, the characteristic speed threshold can be 20 kph, 25 kph, 30 kph, 35 kph, 40 kph, or higher.

[0031] The one or more processors can be collectively configured to apply a speed reduction factor to a modified torque limiting signal, wherein the speed reduction factor varies according to vehicle speed. In such an example, when the vehicle speed is less than a characteristic speed threshold, the speed reduction factor is 1, such that the speed reduction factor does not change the modified torque limiting value. When the vehicle speed is higher than the characteristic speed threshold, the speed reduction factor can decrease from 1 to 0 based on the difference between the characteristic speed threshold and the vehicle speed. The speed reduction factor allows the torque limiting increase to be gradually canceled at higher speeds, where the added torque capability may no longer be needed, or its absence may be less noticeable. The speed reduction factor can be reduced relative to vehicle speed at any suitable rate. For example, the speed reduction factor can be reduced linearly at a rate of 0.1 kph, such that the speed reduction factor decreases from 1 to 0 over a speed range of 10 kph.

[0032] The speed reduction factor can vary above a characteristic speed threshold, depending on any suitable function of vehicle speed. For example, the speed reduction factor can decrease linearly with vehicle speed. For instance, the speed reduction factor can decrease linearly from 1 at the characteristic speed threshold to 0 at the characteristic speed limit. The characteristic speed limit can be any suitable value higher than the characteristic speed threshold. For example, the characteristic speed limit can be 30 kph, 35 kph, 40 kph, 45 kph, 50 kph, or higher. In one example, the characteristic speed threshold is 30 kph, and the characteristic speed limit is 40 kph, such that the modified torque limit value is downmixed to a torque limit between 30 kph and 40 kph.

[0033] Optionally, the one or more processors are jointly configured to: determine whether a limiting condition is met; and, in response to determining that the limiting condition is met, apply a torque limit to the at least one electric traction motor, regardless of whether the determined external condition is an additional torque demand condition. This prevents torque output from exceeding the torque limit in certain cases where the limiting condition is met, such as when additional torque may not be desired or needed, and / or avoids excessive triggering of torque limit mandatory takeover. In some embodiments, the limiting condition is met if: a braking demand signal indicates a required braking pressure; a gradient signal indicates that the gradient of the surface on which the vehicle is supported is less than a gradient threshold; the elapsed time of the external condition being an additional torque demand condition is less than a threshold time period; and / or the vehicle speed exceeds a maximum speed threshold. The limiting condition may require only one of the above conditions to be met for the one or more processors to determine that the limiting condition is met. Alternatively, the limiting condition may require a combination of the above conditions to be met for the one or more processors to determine that the limiting condition is met.

[0034] According to another aspect of the invention, a system is provided that includes a control system comprising the foregoing aspects and at least one electric traction motor. The at least one electric traction motor is controlled by the control system.

[0035] According to another aspect of the invention, a vehicle comprising a system or control system including the foregoing aspects is provided.

[0036] According to another aspect of the invention, a method is provided for controlling at least one electric traction motor in a torque-limited vehicle, wherein the at least one electric traction motor has torque limitation, the method comprising: receiving an indication of an external condition in which the vehicle is operating; determining whether the external condition is an additional torque demand condition; and, based on the determination that the external condition is an additional torque demand condition, outputting a torque limitation forced takeover signal.

[0037] The method may also include any step found in any additional steps in any control system, system of systems, or vehicle of vehicles.

[0038] According to another aspect of the invention, computer-readable instructions are provided, which, when executed by a computer, are arranged to perform the method according to the foregoing aspect.

[0039] Within the scope of this application, it is expressly stated that the various aspects, embodiments, examples, and alternatives set forth in the foregoing paragraphs, in the claims, and / or in the following description and drawings, and in particular their individual features, may be employed independently or in any combination. That is, all embodiments and / or features of any embodiment may be combined in any manner and / or combination unless such features are incompatible. The applicant reserves the right to amend any initially filed claim or accordingly file any new claim, including the right to modify any initially filed claim to incorporate any feature dependent on and / or incorporated into any other claim, although not initially claimed in this manner. Attached Figure Description

[0040] One or more embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

[0041] Figure 1 This is a schematic representation of a control system according to an embodiment of the present invention;

[0042] Figure 2 A vehicle according to an embodiment of the present invention is shown;

[0043] Figure 3 yes Figure 2 A schematic illustration of a portion of a vehicle, including its powertrain and control systems;

[0044] Figure 4 A flowchart illustrating a method according to an embodiment of the present invention is shown;

[0045] Figure 5 The diagram shows the formation. Figure 4 A flowchart of an example method that is part of the method; and

[0046] Figure 6 The illustration is shown according to Figure 4 The method provides a graph of example vehicle behavior. Detailed Implementation

[0047] References in this article Figures 1 to 6 A control system according to an embodiment of the present invention is described. For example... Figure 2As shown, the control system is installed in vehicle 200.

[0048] Reference Figure 1 The diagram illustrates a control system 100 for controlling at least one electric traction motor of a torque-limited vehicle. The control system 100 includes one or more controllers 110.

[0049] like Figure 1 The control system 100 shown includes a controller 110, although it will be understood that this is merely illustrative. The controller 110 includes a processing device 120 and a memory device 130. The processing device 120 may be one or more electronic processing devices 120 operatively executing computer-readable instructions. The memory device 130 may be one or more memory devices 130. The memory device 130 is electrically coupled to the processing device 120. The memory device 130 is configured to store instructions, and the processing device 120 is configured to access the memory device 130 and execute the instructions stored thereon.

[0050] Controller 110 includes an input device 140 and an output device 150. Input device 140 may include an electrical input 140 of controller 110. Output device 150 may include an electrical output 150 of controller 110. Input 140 is arranged to receive an external condition signal 145. External condition signal 145 is an electrical signal indicating the external conditions in which the vehicle is operating. For example, external condition signal 145 may be a slope signal received or derived from an inclinometer, a traction signal received or derived from a tow hook sensor, and / or a terrain signal from a terrain mode selector. External condition signal 145 may include multiple signals, for example, for different sources. External condition signal 145 may include a torque demand signal indicating torque demand from the driver and / or ADAS torque demand, and an acceleration signal indicating the actual acceleration of the vehicle. Although this is referred to as an "acceleration" signal, the signal only needs to provide an indication of acceleration, not acceleration itself. For example, acceleration signal may include information related to the vehicle's speed, from which processing device 120 derives the vehicle's acceleration. The processing device can be configured to determine or derive external conditions based on the difference between the expected acceleration from the torque demand and the actual acceleration, as follows: Figure 5The input is optionally configured to receive one or more additional signals 147 from a controller or sensor associated with the vehicle. For example, from an inclinometer, accelerometer, terrain mode selector, and / or tow hook sensor. Optionally, output 150 is configured to output a torque request signal 155 indicating the torque requested from at least one electric traction motor according to torque demand. Output 150 is configured to output a torque limit forced takeover signal 156 to allow at least one electric traction motor to temporarily increase torque output beyond the torque limit of at least one electric traction motor. Optionally, output 150 is also configured to output a modified torque limit signal 157 for at least one electric traction motor, defining an additional torque limit greater than the torque limit. This is discussed below regarding... Figures 4 to 6 Let's have a more detailed discussion.

[0051] Figure 2 A vehicle 200 according to an embodiment of the present invention is shown. The vehicle 200 includes, as follows: Figure 1 The control system 100 shown is shown.

[0052] Figure 3 It is shown Figure 2A schematic diagram of the powertrain system 300 of vehicle 200. The powertrain system 300 includes at least one electric traction motor configured to provide prime mover power to the vehicle. The powertrain system may include a single electric traction motor or any suitable number of electric traction motors, and may also include one or more internal combustion engines. In the illustrated embodiment, the powertrain system 300 includes a first electric traction motor 312 and a second electric traction motor 314. Each electric traction motor is an electric motor arranged to convert electrical energy into kinetic energy in the form of mechanical torque, and may also be arranged to convert kinetic energy into electrical energy (e.g., during regenerative braking). One or both electric traction motors may be AC ​​induction motors or permanent magnet motors, or another suitable type of motor. Another term for an electric traction motor is an electric drive unit (EDU). Each electric traction motor is configured to drive at least one of the wheels. In the illustrated embodiment, the first electric traction motor 312 is configured to drive the front axle 212 of vehicle 200, and the second electric traction motor 314 is configured to drive the rear axle 214 of vehicle 200. However, it will be understood that the first and second electric traction motors can be interchanged, such that the first electric traction motor 312 drives the rear axle 214 and the second electric traction motor 314 drives the front axle 212. In other embodiments, one or both of the first electric traction motor 312 and the second electric traction motor 314 can be configured to drive the wheels 216 of the vehicle in different ways, such as via a driveshaft and / or via one or more gears, a differential, or a transmission axle, or directly. In other embodiments, the powertrain system may include more than two electric traction motors, such as three or four electric traction motors, each arranged to drive one of the wheels 216 of the vehicle 200. Although the vehicle is shown as having two pairs of wheels 216, it will be understood that the vehicle may have any suitable number of wheels, such as two wheels, three wheels, or more than four wheels. The powertrain system 300 may also include one or more additional prime movers, such as internal combustion engines (not shown). The powertrain system 300 may optionally also include a powertrain controller 320 or a powertrain control module (PCM) configured to control the operation of one or more motor controllers electrically connected to the electric traction motors and / or the prime mover of the powertrain, and configured to receive one or more motor control signals from the control system 100 and / or the PCM 320, and output motor control signals to the electric traction motors 312, 314. In the illustrated embodiment, the powertrain system 300 includes a front motor controller 322 and a rear motor controller 324, but these may be combined into a single motor controller.

[0053] like Figure 3As shown, the control system 100 is electrically connected directly or via one or more other components, such as motor controllers 322, 324, to the first electric traction motor 312 and the second electric traction motor 314. Optionally, the control system 100 is a powertrain controller 320, or includes a powertrain controller 320, or is a part of a powertrain controller 320. Optionally, the control system 100 is a front motor controller 322 and a rear motor controller 324, or includes a front motor controller 322 and a rear motor controller 324, or is a part of a front motor controller 322 and a rear motor controller 324.

[0054] Vehicle 200 also includes an energy storage device 230, such as a traction battery. The energy storage device 230 is configured to deliver electrical energy to a first electric traction motor 312 and a second electric traction motor 314, and optionally receive and store electrical energy generated by the first electric traction motor 312 and the second electric traction motor 314 (e.g., during regenerative braking). The first electric traction motor 312 and the second electric traction motor 314 are optionally electrically connected to the energy storage device 230 via an inverter (not shown). In some embodiments, the energy storage device 230 is communicatively coupled to a powertrain controller 320. The energy storage device 230 may optionally be a high-voltage battery. The energy storage device 230 may have a voltage and capacity supporting electrically driven operation for sustained distances. The energy storage device 230 may have a capacity of several kilowatt-hours to increase range. The capacity may be tens of kilowatt-hours or more than one hundred kilowatt-hours.

[0055] Optionally, vehicle 200 also includes one or more speed sensors configured to output indications of vehicle speed. For example, one or more rotational speed sensors may be associated with electric traction motors 312, 314 to output motor speed signals indicating the rotational speed of one or both electric traction motors 312, 314. Alternatively or additionally, one or more speed sensors may include wheel speed sensors configured to output wheel speed signals indicating the rotational speed of the vehicle's wheels 216. Vehicle 200 includes one or more sensors configured to output signals indicating one or more external conditions in which the vehicle is operating. For example, the vehicle may include one or more of the following: an inclinometer, an accelerometer, a tow hook sensor, and a wheel torque sensor.

[0056] Figure 4 A method 400 according to an embodiment of the present invention is illustrated. Method 400 is for controlling a torque-limited vehicle 200 (e.g., Figure 2 Method 400 is a method for controlling at least one electric traction motor of a torque-limited vehicle (200) shown in the diagram. Specifically, method 400 is a method for controlling at least one electric traction motor of a torque-limited vehicle, wherein at least one electric traction motor has a torque limitation. Method 400 can be... Figure 1 The system 100 shown in the figure executes the method 400 according to an embodiment of the invention. In particular, the memory 130 may include computer-readable instructions that, when executed by the processor 120, perform the method 400 according to an embodiment of the invention.

[0057] At step S-401, the control system 100 receives an indication of the external conditions in which the vehicle is operating, in the form of an external condition signal. The external condition signal is an electrical signal. The term "external condition" refers to aspects of the driving environment in which the vehicle is operating, particularly those aspects that may cause an increase in torque required for the vehicle's movement. This includes, but is not limited to, the slope of the surface on which the vehicle is driven, the type of terrain on which the vehicle is driven, and whether this is terrain that adds torque, such as soft ground, and whether the vehicle is towing a trailer or attached to a tow hook or other equipment otherwise connected to the vehicle.

[0058] Several methods exist for implementing external condition signals. For example, an external condition signal may include a slope signal, such as one received or derived from an inclinometer, indicating the slope of the surface on which the vehicle is supported. Alternatively or additionally, an external condition signal may include, such as one received or derived from a tow hook sensor or a network controller (which indicates when electrical equipment has been inserted into an electrical connector on the tow hook, and / or when a towing procedure has been selected by the driver via an input device such as an infotainment system), indicating the presence of a vehicle trailer connected to the vehicle. Alternatively or additionally, an external condition signal may include, such as one received from a terrain mode selector, indicating the type of terrain on which the vehicle is supported. In such an example, the terrain mode selector may be configured to allow the driver to manually select a terrain mode, such as a soft ground driving mode, and / or to automatically detect and select a terrain mode based on one or more sensors, such as suspension travel sensors, and / or a camera device associated with the vehicle. External condition signals may include multiple signals, for example, for different sources. External condition signals may include torque demand signals indicating torque demand from the driver and / or ADAS torque demand, and acceleration signals indicating the vehicle's actual acceleration. Based on these signals, the control system can determine or derive the external condition based on the difference between the expected acceleration from the torque demand and the actual acceleration. This will be explained below regarding... Figure 5 This will be discussed in more detail. This approach simplifies the detection of additional torque demand conditions by relying on signals that are already safe from a functional safety perspective.

[0059] At step S-402, the control system determines whether the external condition is an additional torque demand condition. An additional torque demand condition is one or more predefined conditions under which the resistance to the vehicle's motion is sufficiently high that, in order to maintain proper vehicle performance, a torque output exceeding the normal torque limit of at least one electric traction motor may be required or necessary. These can be considered unfavorable driving conditions in which additional torque output may be required. Several methods exist for the control system to determine whether an external condition is an additional torque demand condition. This may depend on the nature of the external condition signal.

[0060] For example, in cases where the external condition signal includes a slope signal indicating the gradient of the surface supporting the vehicle, the external condition could be an additional torque demand condition if the gradient exceeds a slope threshold. In other words, this can be determined by assessing whether the gradient exceeds a slope threshold based on the slope signal. The slope threshold can be the value of any suitable incline. The slope threshold can be selected based on one or more of the following: vehicle characteristics, vehicle operating mode, powertrain characteristics, and driver characteristics. For example, the slope threshold could be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, or higher.

[0061] When external condition signals include a towing signal indicating the presence of a vehicle trailer attached to the vehicle, the external condition could be an additional torque demand condition if the towing signal indicates the presence of a vehicle trailer attached to the vehicle. In other words, whether a vehicle trailer is attached to the vehicle can be determined based on the towing signal.

[0062] In cases where the external condition signal includes a terrain signal indicating the type of terrain supporting the vehicle, the external condition can be an additional torque demand condition if the terrain signal indicates that the type of terrain is additional torque terrain. In other words, whether the terrain is additional torque terrain can be determined based on the terrain signal. Additional torque terrain is a surface with higher roll resistance than a standard road surface, and therefore, for a given vehicle acceleration, a higher torque output is required for additional torque terrain. Additional torque terrain can include, but is not limited to, at least one of the following: loose terrain, soft terrain, and / or rough terrain. Example terrain can include gravel, sand, snow, mud, and / or water.

[0063] When the external condition signals include a torque demand signal and an acceleration signal indicating the vehicle's actual acceleration, the additional torque demand condition may require, at least, that the expected acceleration based on the torque demand signal exceeds the actual acceleration by a threshold amount. An example of this determination process will be provided below regarding... Figure 5 Let's have a discussion.

[0064] Determining whether an external condition constitutes an additional torque demand condition may require only one of the above requirements to be met. Alternatively, this determination may require a combination of the above requirements to be met before the external condition is considered an additional torque demand condition.

[0065] If the control system determines that the external conditions are not conditions requiring additional torque, it maintains the torque limit of at least one electric traction motor, and the method ends at step S-420.

[0066] If the control system determines that the external conditions are conditions requiring additional torque, the method may optionally proceed to step S-403 or proceed directly to step S-404.

[0067] Optionally, at step S-403, the control system determines whether a constraint condition is met. In response to determining that the constraint condition is met, the control system torque limit of at least one electric traction motor is maintained, and the method ends at step S-320. Otherwise, the method proceeds to step S-404. Several methods exist for determining whether a constraint condition is met. For example, the control system may receive a braking demand signal, and the constraint condition may include determining, based on the braking demand signal, that braking pressure is requested. The braking demand signal is, for example, an electrical signal indicating a braking pressure request from a brake pedal position sensor. Alternatively or additionally, the control system may receive a slope signal as defined above, and the constraint condition may include determining, based on the slope signal, that the slope of the surface supporting the vehicle is less than a slope threshold. The slope threshold may be the same slope threshold as defined above in the discussion of external conditions. Alternatively or additionally, the control system may be configured to determine the elapsed time of an external condition as an additional torque demand condition. In such an embodiment, the constraint condition may include determining that the elapsed time is less than a threshold time period. This de-jittering reduces potential noise and, when additional torque demand conditions are applied only for a short period, reduces or prevents the control system from forcibly taking over torque limiting. The threshold time period can be any suitable time period. For example, the threshold time period can be 0.5 seconds, 1 second, 1.5 seconds, 2 seconds, or longer.

[0068] At step S-404, the control system outputs a torque limit forced takeover signal. If a greater torque or additional torque is requested, the torque limit forced takeover signal allows at least one electric traction motor to temporarily increase its torque output beyond its torque limit. As will be understood, the torque limit is a preset maximum torque output, which is lower than the maximum torque output capability of at least one electric traction motor. Upon request, the torque limit forced takeover signal enables at least one electric traction motor to provide a torque output exceeding its normal torque limit. The torque limit forced takeover signal can be output to any suitable component of the powertrain, such as directly to at least one traction motor, to an electric motor controller connected to at least one traction motor, or to a powertrain control module connected to at least one traction motor.

[0069] Several methods exist for implementing a torque limit mandatory takeover signal. For example, a torque limit mandatory takeover signal could be a simple instruction to temporarily ignore or cancel the torque limit. In such an example, if such torque output is requested, at least one electric traction motor will be operable to provide the full range of its maximum torque capability. Alternatively, the torque limit mandatory takeover signal could define a further torque limit above the torque limit. This further torque limit could be equal to or less than the maximum torque capability of at least one electric traction motor.

[0070] Optionally, at step S-405, the control system 100 outputs a modified torque limit signal that defines a further torque limit above the torque limit. In this way, at least one electric traction motor will be operable to provide a torque output greater than the torque limit. The further torque limit may be less than the maximum torque capability of at least one electric traction motor.

[0071] Several methods exist for implementing a modified torque limiting signal. For example, the modified torque limiting signal can apply a further torque limit instantaneously, i.e., in a step-like manner from the torque limit to the further torque limit. In other examples, the modified torque limiting signal can be adjusted to define a modified torque limit value that gradually increases from the torque limit to the further torque limit and / or gradually decreases from the further torque limit to the torque limit. The modified torque limit value can gradually increase from the torque limit to the further torque limit at a ramp rate. The ramp rate can be constant. Alternatively, the ramp rate can be different for different conditions and / or vehicle operating parameters.

[0072] Optionally, at step S-406, the control system adjusts the modified torque limit signal to increase the modified torque limit value at an ramp rate, selecting the ramp rate based on a comparison between the torque limit and the torque generated by the powertrain when the external condition is determined to be an additional torque demand condition. For example, when the external condition is determined to be an additional torque demand condition, the control system receives a torque output signal indicating the torque generated by at least one electric traction motor, compares the generated torque with the torque limit, and adjusts the modified torque limit signal based on the comparison. In such an example, the modified torque limit signal can be adjusted to define a modified torque limit value that increases at a ramp rate that varies based on the difference between the generated torque and the torque limit. For example, when the generated torque equals the torque limit, the ramp rate can be set to a slow rate, and as the distance between the generated torque and the torque limit increases, the ramp rate can be set to an increasingly faster rate. This can reduce the degree to which the driver may feel a sudden increase in available torque when the torque output is already at the torque limit in the case of forced torque limit takeover. In one example, the modified torque limit signal is adjusted to increase the modified torque limit value at a first ramp rate when the generated torque is less than the torque limit, and at a second ramp rate when the generated torque is equal to the torque limit.

[0073] Optionally, at step S-407, the control system changes the modified torque limit value according to the vehicle speed. In this way, the forced takeover of the torque limit can occur only at lower speeds where additional torque is most needed and / or be gradually disengaged at higher speeds. In the example step, the control system receives an indication of the vehicle speed, compares the vehicle speed to a characteristic speed threshold, and adjusts the modified torque limit signal based on this comparison. For example, the control system can apply a speed reduction factor to the modified torque limit signal, wherein the speed reduction factor varies according to the vehicle speed. In such an example, when the vehicle speed is less than the characteristic speed threshold, the speed reduction factor is 1, such that the modified torque limit value does not change due to the speed reduction factor. When the vehicle speed is higher than the characteristic speed threshold, the speed reduction factor decreases from 1 to 0 based on the difference between the characteristic speed threshold and the vehicle speed. The speed reduction factor allows the torque limit increase to gradually disengage at higher speeds where additional torque capability may no longer be needed, or where the lack of additional torque capability is less noticeable. The speed reduction factor can decrease relative to the vehicle speed at any suitable rate. For example, the speed reduction factor can decrease linearly at a rate of 0.1 kph, such that the speed reduction factor decreases from 1 to 0 over a speed range of 10 kph. The characteristic speed threshold can be any suitable value. For example, the characteristic speed threshold can be 20 kph, 25 kph, 30 kph, 35 kph, 40 kph, or higher. The speed reduction factor can vary above the characteristic speed threshold as a function of any suitable vehicle speed. For example, the speed reduction factor can decrease linearly with vehicle speed. For example, the speed reduction factor can decrease linearly from 1 at the characteristic speed threshold to 0 at the characteristic speed limit. The characteristic speed limit can be any suitable value higher than the characteristic speed threshold. For example, the characteristic speed limit can be 30 kph, 35 kph, 40 kph, 45 kph, 50 kph, or higher. In one example, the characteristic speed threshold is 30 kph and the characteristic speed limit is 40 kph, such that the modified torque limit value gradually decreases to the torque limit between 30 kph and 40 kph.

[0074] In this implementation, the method ends at step S-420 once the torque limit forced takeover signal has been output.

[0075] Optionally, at step S-408, the control system monitors the external conditions, determines whether the external conditions are still conditions requiring increased torque demand, and restores torque limiting in response to determining that the external conditions are no longer conditions requiring increased torque demand.

[0076] Several methods exist for restoring torque limit. For example, torque limit can be established by ceasing the output of the torque limit mandatory takeover signal in response to determining that the external conditions are no longer conditions that enhance torque demand. In such an example, torque limit can be restored instantaneously. Alternatively or additionally, the control system can output a modified torque limit signal that defines a modified torque limit value, and adjust the modified torque limit signal value to gradually reduce the modified torque limit value back to the torque limit over a descent time period and / or at a descent rate. The descent rate can be constant across multiple scenarios. Alternatively, the descent rate can be different for different conditions and / or vehicle operating parameters. For example, at different vehicle speeds and / or in different vehicle modes. The descent rate can be the same as or different from the ramp rate used to increase the modified torque limit value.

[0077] Once the torque limit has been restored, the method ends at step S-420.

[0078] Figure 5 A method 500 is shown for determining whether an external condition warrants increased torque demand based on a comparison of actual acceleration and expected acceleration. Method 500 is an example process for performing steps S-401 and S-402 of method 400. Method 500 can be... Figure 1 The system 100 shown is used to execute this. Specifically, the memory 130 may include computer-readable instructions that, when executed by the processor 120, perform method 500.

[0079] At step S-501, the control system 100 receives an indication of the external conditions in which the vehicle operates, in the form of an external condition signal including a torque demand signal. The torque demand signal is an electrical signal indicating a torque demand requested by the driver and / or ADAS. Several ways exist to implement the torque demand signal. For example, the torque demand signal may be based on driver input, such as driver input provided by the driver via the accelerator pedal / input. For example, the torque demand signal may be received or derived from an accelerator pedal position sensor signal. Alternatively or additionally, the torque demand signal may be received from or supplemented by a torque demand from a vehicle control system (e.g., an ADAS controller). The torque demand signal may be a wheel-level torque demand derived from the accelerator pedal position torque demand in combination with one or more other signals (such as a vehicle speed limit signal from a stability control system, a modified ADAS torque demand signal, and / or a vehicle speed signal).

[0080] Optionally, at step S-502, the control system 100 outputs a torque request signal for at least one electric traction motor, the torque request signal indicating the torque required to be output from at least one electric traction motor according to a torque demand signal. Several ways exist to implement the torque request signal. In cases where the powertrain includes multiple electric traction motors, the torque request signal may include multiple torque request signals. For Figure 3 The powertrain 300 shown may include a first torque request signal for a first electric traction motor and a second torque request signal for a second electric traction motor, which together provide a combined torque request for the powertrain. The torque request signal may be output directly from the control system 100 to at least one electric traction motor, and / or via a PCM 320, an electric motor controller, or other intermediate components. In some embodiments, the torque request signal may be output by the vehicle's powertrain control module or other controller.

[0081] At step S-503, the control system receives an acceleration signal that provides an indication of the vehicle's actual acceleration. Several ways exist to achieve this indication of the vehicle's actual acceleration. For example, the indication can be based on a signal from an accelerometer mounted on or within the vehicle. The indication can be derived by the control system from a vehicle speed signal. Such a vehicle speed signal can include signals obtained from measurements by speed sensors, such as those from wheel speed sensors or motor rotation speed sensors. The indication of the vehicle's actual acceleration can be received directly from the sensors by the control system, or from one or more other processors in the vehicle that have derived the vehicle speed and / or acceleration and output it to the control system. In this example, the acceleration signal is a motor rotation speed signal, indicating the rotational speed of one or more motors in the powertrain, from which the vehicle speed and therefore the actual vehicle acceleration can be derived. However, the acceleration signal can be a speed signal from a different source (e.g., a wheel speed sensor), or an acceleration signal from an accelerometer mounted on or within the vehicle. The control system 100 determines the actual acceleration based on the acceleration signal. In this example, when the acceleration signal is a motor rotational speed signal, the control system multiplies the motor rotational speed signal by a conversion factor to obtain the vehicle speed signal. The conversion factor takes into account the relationship between the motor's rotational speed and the wheel's rotational speed, as well as the wheel's rolling radius, to convert the motor rotational speed signal into a vehicle speed signal. The control system then calculates the rate of change of the vehicle speed signal to obtain an acceleration signal indicating the vehicle's actual acceleration.

[0082] At step S-504, the control system 100 determines the expected acceleration of the vehicle based on the torque demand. Several ways exist for the control system to determine the expected acceleration. For example, the control system 100 can determine the wheel-level torque demand and convert that torque demand into the expected acceleration using vehicle-specific parameters such as tire rolling radius, estimated road load data, and vehicle mass. In one example, the control system receives the torque demand signal and subtracts the estimated road load data (RLD) torque from the torque demand signal to obtain the acceleration torque value. The RLD torque provides an estimate of the torque loss on the vehicle based on vehicle speed, caused by factors such as rolling resistance, drivetrain losses, and aerodynamic drag. As those skilled in the art will understand, the RLD is typically obtained from testing and generally indicates the torque loss when the vehicle is traveling on a flat road surface. After taking into account the RLD torque loss, the acceleration torque value provides an estimate of the amount of torque required to accelerate the vehicle. The acceleration torque value is divided by the wheel rolling radius to obtain the acceleration force value. The acceleration force value is divided by an estimate of the vehicle mass to obtain the expected acceleration value. In this way, since the wheel torque request signal limits the torque demand in units of torque, the control system determines the vehicle's expected acceleration based on the torque demand.

[0083] At step S-505, the control system 100 compares the actual acceleration obtained during step S-504 with the expected acceleration obtained during step S-505.

[0084] At step S-506, the control system determines whether the external conditions constitute an additional torque demand condition. To achieve this, the control system 100 determines whether the expected acceleration exceeds the actual acceleration by at least a threshold amount based on the comparison during step S-505. Several methods exist in which the comparison of the expected acceleration with the actual acceleration and the determination of whether the expected acceleration exceeds the actual acceleration by at least a threshold amount can be implemented. For example, the amount of the actual acceleration can be subtracted from the amount of the expected acceleration to obtain an acceleration difference, and then the acceleration difference can be compared with a threshold amount to determine whether the acceleration difference is equal to or greater than the threshold amount. Alternatively or additionally, the threshold amount can be added to the actual acceleration measure, and the sum can be compared with the expected acceleration measure to see if the sum is equal to or greater than the expected acceleration measure. Before the comparison, one or both of the actual acceleration signal and the expected acceleration signal can be half-wave rectified, i.e., clipped at zero, so that only positive values ​​of acceleration are considered. In this example, the actual acceleration signal and the expected acceleration signal are clipped at zero so that only positive values ​​of acceleration are used. The actual acceleration is then subtracted from the expected acceleration to obtain the acceleration difference. This acceleration difference is compared to a threshold value to determine whether it is equal to or greater than the threshold value.

[0085] The threshold value can be any suitable value. The threshold value can be constant. For example, the threshold value can be set to 1 m / s. 2 2 m / s 2 3 m / s 2 4 m / s 2 5 m / s 2 Or higher. The threshold value can vary based on one or more operating conditions or vehicle parameters. For example, the threshold value can vary based on vehicle speed. The threshold value can be stored in memory and accessed by the control system from the memory. Alternatively or additionally, the threshold value can be determined by the control system according to a lookup table, in which the threshold value is defined relative to one or more operating conditions or vehicle parameters.

[0086] If the control system determines that the expected acceleration exceeds the actual acceleration by at least a threshold amount, the control system will also determine that the external condition is an additional torque demand condition, and the method proceeds to step S-404, as described above. Figure 4 As discussed. If the control system determines that the expected acceleration is not more than a threshold amount than the actual acceleration, the control system will determine that the external condition is not an additional torque demand condition, and the process will proceed to S-420 and end, as... Figure 4 As shown in the image.

[0087] Figure 6 A graph 600 is shown illustrating the vehicle behavior when the method 400 described above is followed. Graph 600 includes several graphs illustrating how various signals associated with method 600 change relative to each other during a start-up on a slope. In this scenario, the vehicle is facing forward toward the slope and accelerating from a standstill.

[0088] Graph (a) illustrates the relationship between torque output and torque limit applied to the powertrain. Graph (a) shows the variation of torque (in Nm) along the y-axis relative to time along the x-axis. Graph (a) includes: a torque output signal 601 indicating the actual torque output from at least one electric traction motor in the powertrain; a torque limit 602 indicating the torque limit value applied to at least one electric traction motor; a maximum torque capability 603 indicating the maximum possible torque output from at least one electric traction motor; and a modified torque limit signal 604 indicating the modified torque limit value applied to at least one electric traction motor when the torque limit is forcibly taken over.

[0089] Graph (b) shows the change of vehicle speed (in km / h) along the y-axis relative to time on the x-axis. Graph (b) includes an indication of vehicle speed in the form of vehicle speed signal 610. In this example, vehicle speed signal 610 is a direct measurement of vehicle speed obtained from a wheel rotation sensor. However, the vehicle speed signal can be any indication of vehicle speed, such as a motor rotation speed signal, which can be converted into a vehicle speed measurement by the control system.

[0090] Graph (c) shows the torque demand over time. Graph (c) includes an indication of torque demand in the form of a torque demand signal 620. In this example, the torque demand signal 620 is an accelerator pedal position signal from an accelerator pedal position sensor and is shown as a percentage of the total accelerator pedal travel along the y-axis (where 0% indicates the accelerator pedal is not depressed and 100% indicates the position is fully depressed) versus time on the x-axis.

[0091] At time t0, the vehicle is stationary, the accelerator pedal is not depressed, the torque output is zero, and a torque limiter is applied. Therefore, the torque output signal 601 is zero, the vehicle speed signal 610 is zero, and the torque demand signal 620 is zero.

[0092] At time t1, the driver begins to depress the accelerator pedal, and as a result, the torque demand signal 620 and the torque output signal 601 begin to rise. At this time, the vehicle speed signal 610 remains at zero, indicating that the vehicle is still stationary.

[0093] At time t2, the vehicle speed signal 610 begins to decrease, indicating that although the torque output has not decreased, the vehicle is decelerating, and the driver responds by adjusting the accelerator pedal position to increase the vehicle speed, as indicated by the increase in the torque demand signal 620 and the torque output signal 604. This decrease in speed indicates that external conditions have made the vehicle's acceleration more difficult than under typical driving conditions. For example, the gradient of the slope may have increased and / or the terrain may have changed to a higher-resistance type, such as mud or sand.

[0094] During this process, the control system monitors the torque demand signal 620 and the vehicle speed signal 610 to determine and compare the expected vehicle acceleration with the actual vehicle acceleration, for example, as described above. Figure 5 In summary, the torque demand signal 620 and the vehicle speed signal 610 provide the control system with indications of external conditions, which the control system can use to determine whether the external conditions constitute an additional torque demand condition.

[0095] Between t2 and t3, although the torque demand signal 620 continues to increase, the vehicle speed signal 610 continues to decrease. Therefore, the actual acceleration decreases to below the expected acceleration and exceeds a threshold amount, and the control system determines that the external conditions in which the vehicle operates are now an additional torque demand condition. The control system performs a de-jittering step, in which it determines the elapsed time period during which the actual acceleration remains below the expected acceleration and compares this elapsed time period with a threshold time period used for implementation. At time t3, once the elapsed time has exceeded the threshold time period, the control system outputs a torque limit forced takeover signal, indicating that the torque limit 602 can be temporarily ignored. In this example, the control system outputs a modified torque limit signal 604 to define a modified torque limit value that gradually increases from the torque limit 602 to the maximum torque capability 603 within a ramp time period defined by (t4-t3) and at a ramp rate defined by (maximum torque capability - torque limit) / (t4-t3). Since the actual powertrain torque output indicated by torque output signal 601 at time t3 is less than torque limit 602, the control system increases the modified torque limit value at a rapid ramp rate. If the torque output is already at the torque limit at time t3, the control system can use a slower ramp rate to prevent any sudden increase in actual torque output when the torque limit is forcibly taken over.

[0096] At time t4, the torque limit is forcibly taken over, and the modified torque limit signal has increased the available torque to the maximum torque capability 603. This allows the torque output to exceed the torque limit 602.

[0097] At time t5, the vehicle speed signal 610 begins to increase due to the additional torque output provided by at least one electric traction motor, and the driver maintains the torque demand and torque output at a substantially constant level.

[0098] At time t6, the driver completely lifts off the accelerator, causing the torque demand signal 620 and shortly thereafter the torque output signal 601 to drop to zero, and the vehicle comes to a stop.

[0099] At time t7, the torque output signal 601, vehicle speed signal 610, and torque demand signal 620 are all zero, and the control system determines that the expected acceleration (now zero) no longer exceeds the threshold by a greater amount than the actual acceleration (also now zero), and this situation does not occur during the elapsed time of the threshold exceeding period. Therefore, the control system determines that the external condition is no longer an additional torque demand condition and the torque limit can be restored. The control system restores the torque limit by adjusting the modified torque limit signal to gradually reduce the modified torque limit value from the maximum torque capacity 603 back to the torque limit 602 within a ramp-up time period defined by (t8-t7) and at a ramp-down rate defined by (torque limit - maximum torque capacity) / (t8-t7). It can be seen that the ramp-down rate is slower than the ramp-up rate of increasing the modified torque limit when the torque limit is released.

[0100] At time t8, torque limit 602 has been reapplied to the powertrain, and the method ends.

[0101] In this way, the control system can determine when the external conditions in which the vehicle operates necessitate an additional torque output beyond the torque limit to ensure proper acceleration.

[0102] It should be understood that various changes and modifications can be made to this invention without departing from the scope of this application.

Claims

1. A control system for controlling at least one electric traction motor of a torque-limited vehicle, wherein, The at least one electric traction motor has a torque limit, and the control system includes one or more processors, which are collectively configured to: Receive instructions regarding the external conditions in which the vehicle is operating; Determine whether the external conditions constitute an additional torque demand condition; and Based on the determination that the external condition is an additional torque demand condition, a torque limit forced takeover signal is output.

2. The control system according to claim 1, wherein: The indications of external conditions include one or more of the following: A slope signal, the slope signal indicating the slope of the surface on which the vehicle is supported; A towing signal, the towing signal indicating the presence or absence of a vehicle trailer connected to the vehicle; and Terrain signals, the terrain signals indicating the type of terrain on which the vehicle is supported; and The external condition is an additional torque demand condition in the following cases: The slope is greater than the slope threshold; The traction signal indicates the presence of a vehicle trailer connected to the vehicle; and / or The terrain signal indicates that the type of terrain is additional torque terrain.

3. The control system according to claim 1 or 2, wherein, The indications of external conditions include an indication of the vehicle's actual acceleration and an indication of torque demand, wherein the one or more processors are collectively configured to: Based on the torque requirement, determine the expected acceleration of the vehicle; and The expected acceleration is compared with the actual acceleration, wherein the external condition is an additional torque demand condition if the expected acceleration exceeds the actual acceleration by at least a threshold amount.

4. The control system according to claim 3, wherein, The one or more processors are collectively configured to: receive a rotational speed signal indicating the rotational speed of the at least one electric traction motor, and determine the actual acceleration based on the motor rotational speed.

5. The control system according to any of the preceding claims, wherein, The torque limit forced takeover signal includes a modified torque limit signal that defines a further torque limit above the stated torque limit.

6. The control system according to claim 5, wherein, The one or more processors are collectively configured to: adjust the modified torque limit signal to define a modified torque limit value, the modified torque limit value being gradually increased from the torque limit to the further torque limit and / or gradually decreased from the further torque limit to the torque limit.

7. The control system according to claim 6, wherein, The one or more processors are collectively configured to adjust the modified torque limit signal to gradually increase the modified torque limit value from the torque limit to the further torque limit at an escalation rate that varies according to one or more vehicle operating parameters.

8. The control system according to claim 7, wherein, The one or more processors are configured together to: When it is determined that the external condition is an additional torque demand condition, a torque output signal indicating the torque generated by the at least one electric traction motor is received; The generated torque is compared with the torque limit; as well as In response to the comparison, the modified torque limit signal is adjusted to increase the modified torque limit value at a first ramp rate when the generated torque is less than the torque limit, and to increase the modified torque limit value at a second ramp rate slower than the first ramp rate when the generated torque is the same as the torque limit.

9. The control system according to any one of claims 6 to 8, wherein, The one or more processors are configured together to: Monitor whether the external conditions remain in a state of additional torque demand; and In response to determining that the external conditions are no longer an additional torque demand condition, the torque limit is restored by adjusting the modified torque limit signal to gradually reduce the modified torque limit value from the further torque limit to the torque limit at a descent rate that varies according to one or more vehicle operating parameters.

10. The control system according to any one of claims 6 to 9, wherein, The one or more processors are configured together to: Receive vehicle speed instructions; The vehicle speed is compared with a characteristic speed threshold. as well as In response to determining that the vehicle speed exceeds the characteristic speed threshold, the modified torque limit signal is adjusted according to the vehicle speed to gradually reduce the modified torque limit value from the further torque limit to the torque limit.

11. The control system according to any of the preceding claims, wherein, The one or more processors are configured together to: Determine whether the restrictions are met; and In response to determining that the constraint condition is met, the torque limit is applied to the at least one electric traction motor, regardless of whether the external condition is determined to be an additional torque demand condition. The aforementioned restriction conditions are satisfied under the following circumstances: The braking demand signal indicates a request for braking pressure. The slope signal indicates that the slope of the surface on which the vehicle is supported is less than a slope threshold; The external condition is that the elapsed time of the additional torque demand condition is less than a threshold period; and / or The vehicle speed exceeds the maximum speed threshold.

12. A system comprising a control system according to any of the preceding claims and at least one electric traction motor.

13. A vehicle comprising the system according to claim 12 or the control system according to claims 1 to 11.

14. A method for controlling at least one electric traction motor in a torque-limited vehicle, wherein, The at least one electric traction motor has a torque limit, and the method includes: Receive instructions regarding the external conditions in which the vehicle is operating; Determine whether the external conditions constitute an additional torque demand condition; and Based on the determination that the external condition is an additional torque demand condition, a torque limit forced takeover signal is output.

15. A computer-readable instruction, which, when executed by a computer, is arranged to perform the method according to claim 14.

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