System and method for managing stall torque limit

Abstract

The present disclosure relates to systems and methods for managing stall torque limits. A system for managing motor torque in a vehicle determines a stall speed amount corresponding to a motor speed and determines a torque limit based on the stall speed amount. The system determines a desired torque value and determines whether to generate a modification to one or more baseline torque commands based on the desired torque value and the torque limit. If the baseline torque command is not modified, the system generates the one or more baseline torque commands corresponding to one or more motors. If the baseline torque is modified, the system generates one or more modified torque commands corresponding to the one or more motors based on the modification and based on the one or more baseline torque commands. The modified torque commands can include a minimum value less than the torque limit and a maximum value corresponding to a wheel slip torque.

Description

Technical Field

[0001] This disclosure relates to torque control for electric vehicles, and more specifically to improved torque control near stall conditions. Summary of the Invention

[0002] In some embodiments, this disclosure relates to a method for managing motor torque in a vehicle. The method includes determining a stall amount corresponding to a motor speed, determining a torque limit based on the stall amount, determining a desired torque value, and determining, based on the desired torque value and the torque limit, whether to generate a modification to one or more baseline torque commands. If the baseline torque commands are not modified, the method includes generating the one or more baseline torque commands corresponding to the one or more motors. If the baseline torque is modified, the method includes generating one or more modified torque commands corresponding to the one or more motors based on the modification and based on the one or more baseline torque commands.

[0003] In some implementations, generating the one or more modified torque commands includes retrieving reference information, determining a baseline torque command, modifying the baseline torque command based on the reference information to generate the modified torque command, and sending the modified torque command to a power electronics system coupled to the one or more motors.

[0004] In some implementations, the modified torque command includes a baseline torque command and at least one of a square wave, a pulse-modulated wave, a pulse density wave, a sawtooth wave, a triangular wave, a sine wave, or a piecewise function wave.

[0005] In some implementations, determining whether to generate the modification to the one or more baseline torque commands includes determining a reference operating range and determining whether the stall velocity and the desired torque value are within the reference operating range.

[0006] In some implementations, the one or more modulated torque commands include a time average indicating the desired torque value.

[0007] In some embodiments, the method includes retrieving reference information based on the stall velocity quantity, wherein the reference information includes the torque limit. For example, in some embodiments, the reference information is included in a database or other data structure stored in memory.

[0008] In some implementations, determining the desired torque value includes receiving input indicating the desired torque value from an operator input interface.

[0009] In some embodiments, the method includes determining a peak torque command corresponding to wheel slip torque, and incrementing at least one of the one or more motors in angular position based on the torque command. The peak value of the one or more modified torque commands corresponds to the peak torque command. In some embodiments, each of the one or more modified torque commands includes a minimum value less than the torque limit and a maximum value corresponding to wheel slip torque.

[0010] In some embodiments, this disclosure relates to a method for managing motor torque in a vehicle, the method comprising determining an operating range of one or more motors based on rotational speed and a desired torque value, retrieving a reference operating range from a memory, and determining a torque command mode based on the operating range and the reference operating range. The method includes applying a first torque command mode if the operating range is within the reference operating range. The method also includes applying a second torque command mode if the operating range is not within the reference operating range. In some embodiments, the second torque command includes a baseline command and modulation.

[0011] In some embodiments, this disclosure relates to a system for managing motor torque in a vehicle. For example, the system may implement the methods disclosed herein. The system includes a sensor configured to sense motor speed and control circuitry coupled to the sensor. The control circuitry is configured to determine a stall amount corresponding to the motor speed, determine a torque limit based on the stall amount, determine a desired torque value, and determine, based on the desired torque value and the torque limit, whether to generate a modification to one or more baseline torque commands. If the baseline torque command is not modified, the system generates the one or more baseline torque commands corresponding to the one or more motors. If the baseline torque is modified, the system generates one or more modified torque commands corresponding to the one or more motors based on the modification and the one or more baseline torque commands. In some embodiments, the system includes a power electronic system coupled to the control circuitry and the one or more motors. For example, in some embodiments, the power electronic system is configured to receive torque commands from the control circuitry. Attached Figure Description

[0012] This disclosure is described in detail with reference to the following figures, according to one or more various embodiments. The figures are provided for illustrative purposes only and depict only typical or exemplary embodiments. These figures are provided to facilitate understanding of the concepts disclosed herein and should not be considered as limitations on the breadth, scope, or applicability of these concepts. It should be noted that these figures are not necessarily drawn to scale for clarity and ease of illustration.

[0013] Figure 1A perspective view of an exemplary vehicle nearing stall according to some embodiments of the present disclosure is shown;

[0014] Figure 2 A system diagram of an exemplary vehicle having multiple motors according to some embodiments of the present disclosure is shown;

[0015] Figure 3 A system diagram of an exemplary system for managing wheel torque according to some embodiments of the present disclosure is shown;

[0016] Figure 4 A flowchart illustrating an exemplary process for managing wheel torque according to some embodiments of the present disclosure is shown;

[0017] Figure 5 A flowchart illustrating an exemplary process for managing wheel torque based on reference information according to some embodiments of the present disclosure is shown;

[0018] Figure 6 A graph illustrating exemplary torque schemes below the continuous stall torque limit for a multi-motor system according to some embodiments of the present disclosure is shown.

[0019] Figure 7 A graph illustrating exemplary torque schemes for a multi-motor system at or near the continuous stall torque limit according to some embodiments of this disclosure is shown.

[0020] Figure 8 A graph illustrating an exemplary torque scheme for a multi-motor system according to some embodiments of the present disclosure is shown, which exhibits an increasing torque value in the presence of some increments; and

[0021] Figure 9 An exemplary torque scheme for a motor is shown according to some embodiments of the present disclosure. Detailed Implementation

[0022] This disclosure relates to systems and methods for controlling motors in electric vehicles at speeds as low as zero. For illustration, when the electric vehicle is completely or very close to a standstill, motor torque can only be generated via a finite number of continuous currents in one or more phases of the motor coils. Applying current continuously to one or more phases of the motor can increase heating and temperature of the motor and power electronics, which can shorten operational life.

[0023] Figure 1A perspective view of an exemplary vehicle 100 near stall according to some embodiments of the present disclosure is shown. As shown, vehicle 100 is positioned on a slope 110 (e.g., during climbing, off-roading, or traversing), but the present disclosure can be applied to vehicles traversing any flat or sloping surface. For example, when on a slope, the driver can (e.g., by actuating the pedals) request increased torque to transition from a stationary position to some motion. Because vehicle 100 is stationary, the torque required to maintain the zero-speed condition can depend on the slope, the weight of vehicle 100, ground characteristics, or a combination thereof. Furthermore, because being in or near stall conditions corresponds to a relatively low rotational rate, a constant current may be disproportionately applied to a particular phase, which can lead to overheating (e.g., thus requiring, in some cases, a torque derating level as specified in the motor specifications). Figure 1 As shown, the forces acting on the vehicle include gravity, normal forces from the ground, static friction, and dynamic friction (e.g., if the vehicle exhibits some non-zero speed), while the torque from the electric motor applies a force at the contact area between the wheels of vehicle 100 and ramp 110. The systems and methods of this disclosure relate to improving the torque capability of vehicle 100 under conditions of or near stall.

[0024] Figure 2 A system diagram of an exemplary vehicle 200 having multiple motors according to some embodiments of the present disclosure is shown. For illustration, vehicle 200 can be coupled with... Figure 1 The vehicle 100 is identical. Motor assemblies 201, 202, 203, and 204 may each include an electric motor, a gearbox (e.g., a reduction gear set or pulley set), a coupling (e.g., to one of wheels 211 to 214, as shown), auxiliary systems (e.g., a lubrication system, a cooling system, a power electronics system), any other suitable components, or any combination thereof. As shown, each motor assembly 201 to 204 is coupled to the control system 250 via a coupling 220, which may include power leads, control wires, sensor wires, a communication bus, any other suitable coupling type, or any combination thereof. For example, in some embodiments, the control system 250 includes a battery pack or is otherwise coupled to a battery pack and is configured to supply power (e.g., current) to the electric motors of the motor assemblies 201 to 204.

[0025] The control system 250 can be configured to generate torque commands for each of the motor assemblies 201 to 204. In some embodiments, the control system 250 generates control signals for each of the motor assemblies 201 to 204. Control signals may include messages, current values, pulse width modulation (PWM) values, any other suitable values, any other information indicating desired operation, or any combination thereof. For example, the control system 250 may include a speed controller (e.g., a proportional-integral-derivative (PID) feedback controller), a torque controller, a current controller (e.g., each motor phase of each motor), a position controller, any other suitable controller, or any combination thereof.

[0026] In some embodiments, the control system 250 is configured to strategically station the electric motors of one or more motor assemblies 201 to 204 between two phases, and then share the load when current is supplied. In some embodiments, the cooling capacity of the electric motors (e.g., those of motor assemblies 201 to 204) is significantly reduced for any given stall torque requirement compared to when the motor shaft is rotating. Therefore, the continuous stall torque capacity may be limited due to the accumulation of excess heat. Once the motor shaft begins to rotate at a very low speed, the torque is then supported uniformly by all coil phases over time, and the continuous torque rating can be increased. In vehicles utilizing two or more motors (e.g., vehicle 200, as shown, includes four motors), this disclosure provides strategies to mitigate this phenomenon and increase the continuous stall torque capacity. For illustrative purposes, vehicle 200 is a four-wheeled vehicle with one motor per wheel. In some cases, such as Figure 1 As shown, vehicle 200 may stop on a significant incline (e.g., on a slope). Figure 1 On a slope 110, the surface may be off-road and rocky. Vehicle 200 may attempt to climb the slope by using motor assemblies 201 to 204 to apply torque to each of the wheels 211 to 214.

[0027] Figure 3 A system diagram of an exemplary system 300 for managing wheel torque according to some embodiments of the present disclosure is shown. For illustration, system 300 can be implemented as... Figure 2 The control system 250 or a part thereof is used to control the vehicle (e.g., Figure 1 Vehicle 100 or Figure 2 The electric motor of the vehicle 200. As shown in the figure, the system 300 includes a control circuit 320, an operator input interface 310, reference information 315, a motor driver 350 and an electric motor 360.

[0028] As shown in the figure, the control circuit 320 includes a processor 321, a memory 322, a communication (COMM) interface 323, a sensor interface 324, a determination module 325, a plan generator 326, and a signal generator 327. The processor 321 may include any suitable processing device, such as a central processing unit with a single or dual core, a bus, logic circuitry, integrated circuits, a digital signal processor, a graphics processor, any other suitable component for reading and executing computer instructions, or any combination thereof. The memory 322 may include any suitable storage device, such as, for example, volatile memory, non-volatile memory, removable storage devices, solid-state storage devices, optical devices, magnetic devices, any other suitable component for storing and retrieving information, or any combination thereof. The COMM interface 323 may include electrical terminals, a level shifter, a communication module, a connector, a cable, an antenna, any other suitable component for transmitting and receiving information, or any combination thereof. For example, the COMM interface 323 may include an Ethernet interface, a WiFi interface, an optical interface, any other suitable wired or wireless interface, or any combination thereof. Sensor interface 324 may include a power supply, analog-to-digital converter, digital-to-analog converter, signal processing device, signal conditioning device, connector, electrical terminals, any other suitable components for managing signals to and from the sensor, or any combination thereof. For example, sensor interface 324 may be configured to communicate with a current sensor, a position sensor (e.g., a rotary encoder coupled to a motor shaft or gear shaft), a temperature sensor, a voltage sensor, an accelerometer (e.g., a vibration sensor), any other suitable sensor, or any combination thereof. Determination module 325 is configured to determine whether to modify the torque command or apply a constant torque command. Plan generator 326 may be implemented in hardware, software, or a combination thereof to generate a torque plan as a sequence of values ​​(e.g., if determination module 325 determines to generate a non-constant or otherwise modified torque plan). Signal generator 327 is configured to send control signals indicative of the torque plan generated by plan generator 326 to motor drive 350, motor controller, any other suitable processing device or communication interface, or any combination thereof. For example, signal generator 327 can convert the value of the torque plan into voltage, bit, message, or any other suitable data for transmission to a receiver (e.g., signal interface 351). Signal generator 327 can generate, for example, electrical signals, electromagnetic signals (e.g., via photons of any suitable wavelength including radio, visible, or infrared light), any other suitable signals, or any combination thereof.

[0029] In an illustrative example, reference information 315 may include a reference operating range, speed-torque mapping, torque limits, temperature limits, equipment information, operator information, thresholds or limit values, baseline torque plans, torque command modifications (e.g., modulation), torque functions (e.g., parameters thereof), any other suitable reference information, or any combination thereof. For example, reference information 315 may include a reference operating range comprising a set of coordinate pairs (e.g., or a higher-dimensional set) defining the values ​​of operating parameters for the expected operating range. Operating parameters may include speed (e.g., rpm, rotational speed, or angular velocity of the motor or its attached wheels), torque (e.g., force x distance, force), current (e.g., current in a motor phase, total motor current), temperature (e.g., coolant temperature, motor winding temperature, power electronics temperature), any other suitable parameters, or any combination thereof. For illustration, operating range 330 is shown as a two-dimensional operating range with points A, B, and C. In another example, reference information 315 may include a speed-torque mapping that includes a mapping of speed values ​​and torque values ​​(e.g., a function mapping, an ordered set of pairs) that defines torque limits as a function of speed (e.g., motor speed or wheel speed). In another example, reference information 315 may include torque limits such as values ​​(e.g., one or more values ​​optionally indexed by speed), torque parameter mappings (e.g., a function mapping or lookup table of torque and temperature, speed, or another parameter), proportionality constants (e.g., in torque / speed units), any other suitable limits, or any combination thereof. In another example, reference information 315 may include temperature limits such as coolant temperature limits, power electronics temperature limits, motor winding temperature limits, any other suitable temperature limits, or any combination thereof. In another example, reference information 315 may include device information including manufacturer-specified limits, current capacity, torque capacity, torque limits mapped to parameters (e.g., speed, temperature), peak torque values, peak current values, inherent frequencies (e.g., for vehicle components or systems), any other suitable information about the motor or power electronics, or any combination thereof. In another example, reference information 315 may include operator information, such as operator preferences, predetermined limits, one or more optional modes, any other suitable information corresponding to the operator or selected by the operator, or any combination thereof. In another example, reference information 315 may include thresholds or limit values, such as current limits, temperature limits, speed limits, frequency limits, time limits, any other suitable limits, or any combination thereof. In another example, reference information 315 may include a baseline torque plan, such as a constant value, a baseline value, a modified plan (e.g., a function or modulation), a waveform, a piecewise function, a pulse type, a frequency value, a period value, a duration value, any other suitable information used to determine the torque plan, or any combination thereof.In another example, reference information 315 may include torque command modification (e.g., modulation), torque function (e.g., a piecewise function defined over a domain), any other suitable information for modifying the baseline torque command, frequency information, or any combination thereof. For illustration, torque function may include peaks, impulses, wavelets, sine functions, polynomials, piecewise functions, any other suitable function, or any combination thereof.

[0030] In an illustrative example, referring to operating range 330, if the X and Y dimensions correspond to speed and torque, respectively, then point A refers to a zero-speed torque command within the operating range, point B refers to a zero-speed torque command outside the operating range, and point C refers to a specific speed torque command within the operating range. In some embodiments, the system does not need to modify the torque command during operation at points A or C. In some embodiments, the system determines that point B is inoperable, or otherwise only temporarily operable. For example, in some embodiments, if an operating point is desired at point B, the system may modify, limit, or otherwise reduce the torque command to fall within the operating range. In some embodiments, if the desired operating point is close to the boundary of the operating range (e.g., within a given interval of torque, speed, or other parameters), the system may determine to modify (e.g., modulate) the torque command to prevent motor overheating.

[0031] As shown in the figure, the motor driver 350 includes a signal interface 351, a power electronic device 352, and a sensor interface 353. The signal interface 351 is configured to receive control signals from the control circuitry 320. For example, the signal interface 351 may include electrical terminals, amplifiers, filters, signal conditioners, level shifters, analog-to-digital converters, antennas, cables, any other suitable hardware or software components, or any combination thereof. For example, the control signal may include a PWM signal, a pulse density modulation (PDM) signal, an analog signal, a square wave, a modulated carrier signal, any other suitable signal, or any combination thereof. In another example, the control signal may be transmitted using a wired interface, a wireless interface, an optical interface, any other suitable interface, or any combination thereof. The power electronic device 352 may include IGBTs, MOSFETs, switches, diodes, any other suitable components, or any combination thereof. For example, in some embodiments, the power electronic device 352 includes (e.g., electrically arranged between DC buses) one or more H-bridge circuits or (e.g., a half-bridge circuit with a delta-Y or star neutral connection). Sensor interface 353 may include one or more sensors, a power supply, an interface for receiving and processing sensor signals, any other suitable components, or any combination thereof. For example, sensor interface 353 may include a current sensor (e.g., DC bus current, motor phase current), a temperature sensor (e.g., indicating the temperature of a switch or other current-carrying device), a voltage sensor, a speed sensor (e.g., coupled to one or more electric motors 360), any other suitable sensor for sensing any suitable parameter, or any combination thereof.

[0032] Electric motor 360 includes one or more electric motors, each including a motor winding 361 and an optional motor cooling device 362. For example, in some embodiments, each of the one or more electric motors 360 includes a motor winding 361 corresponding to one or more phases of the respective motor. For illustration, electric motor 360 may include a three-phase motor, a four-phase motor, a DC motor, a switched reluctance motor, any other suitable motor with any suitable commutation, or any combination thereof. Motor cooling device 362 may include, for example, a cooling jacket, a housing having channels for coolant, cooling fins, any other suitable components, or any combination thereof. For illustration, a cooling system with a pump and a reservoir may be coupled to motor cooling device 362 to maintain, reduce, or otherwise control the temperature of electric motor 360.

[0033] In an exemplary example, the vehicle may include system 300, which includes control circuitry 320, a motor driver 350, and an electric motor 360. Reference information 315 may be included in memory 322 or retrieved from an external source via COMM interface 323 (e.g., via a wired or wireless interface). The vehicle may include a pedal that serves as an operator input interface 310 to provide the operator with a request for torque.

[0034] In another illustrative example, the motor of electric motor 360 may have a corresponding set of specifications, such as including four coil phases, a continuous stall rating of 60 Nm, and a continuous torque limit of 90 Nm at low speeds. The systems and methods disclosed herein provide the ability to extend the stall torque thermal limit to the RMS thermal limit of a liquid-cooled (e.g., or air-cooled) electric motor. For illustration, in some cases, when the torque limit is applied in other ways, the vehicle can stop and start on steeper, continuous inclines, which may be useful for off-road operations.

[0035] Figure 4 A flowchart illustrating an exemplary process 400 for managing wheel torque according to some embodiments of the present disclosure is shown. For illustration, in some embodiments, process 400 may use... Figure 3 The system 300 is used to achieve this.

[0036] Step 402 involves the system determining a stall amount corresponding to the motor speed. In some embodiments, the stall amount may include motor speed, motor position, wheel speed, gear speed (e.g., gearbox speed between the motor and the wheel), any other suitable speed, or any combination thereof. The stall amount may indicate an rpm value, angular position, angular velocity, angular increment (e.g., cogging increment or phase increment), any other suitable indicator of angular position information, or any combination thereof. For illustration, the system may determine a valid rpm value by time averaging, sampling (e.g., selecting a single sample value), sample averaging, applying RMS calculations, applying filters, applying any other suitable techniques for indicating speed, or any combination thereof. The system may determine the stall amount based on one or more encoders, speed sensors, magnetic pickups, optical systems, image-based systems, any other suitable sensors for sensing speed or angular position, or any combination thereof. In some embodiments, the vehicle may include multiple motors, and the system may determine the stall amount for each of the multiple motors.

[0037] Step 404 includes the system determining the torque limit based on the stall velocity. In some embodiments, the system can access reference information by retrieving or otherwise (e.g., Figure 3The torque limit is determined by reference information 315. The torque limit can be predetermined based on the motor's temperature limits, cooling capacity, and the expected heat generated by the phase current. In some embodiments, the torque limit is determined from (e.g., stored in...) Figure 3 The torque limit is retrieved from a lookup table in memory 322. In some embodiments, the vehicle may include multiple motors, and the system may determine the torque limit of each of the multiple motors.

[0038] Step 406 includes the system determining a desired torque value. In some embodiments, the desired torque value is determined based on operator input (e.g., at operator input interface 310). In some embodiments, the vehicle may include multiple motors, and the system may determine a desired torque value for each motor. For example, the system may implement torque vectoring to provide more torque to specific wheels (e.g., front wheels, rear wheels, wheels with a higher coefficient of friction with the ground). In some embodiments, the system determines a desired torque value corresponding to a period of time. For example, the system may update or latch the desired torque value at any suitable frequency or interval.

[0039] Step 408 involves the system determining whether to modify one or more torque commands based on the desired torque, torque limits, operating range, any other suitable criteria, or any combination thereof. In some cases, the desired torque value in step 406 may be close to or exceed the torque limits in step 404. In some such cases, the system may determine whether to apply the desired torque value relative to the possibility of motor overheating. In some embodiments, the system determines whether to apply the desired torque value directly or modify the applied torque value to prevent exceeding motor capacity. In some embodiments, the system compares the desired torque value to the torque limits of each motor and then determines whether to modify the applied torque command based on that comparison.

[0040] In some implementations, at step 408, the system compares the desired torque value with the torque limit of each motor, and if the desired torque value exceeds the torque limit, the system determines that a modification should be applied. In some implementations, at step 408, the system compares the desired torque value with the torque limit of each motor, and if the desired torque value is within a threshold of the torque limit (e.g., within 10%, 5%, or 1%, or within an offset of X Nm), the system determines that a modification should be applied. In some implementations, the system may have access to reference information (e.g., Figure 3 The reference information (315) may include a lookup table, function mapping, or any other suitable algorithm for determining whether to modify the torque command. If the system determines not to modify the applied torque command, the system may proceed to step 410. If the system determines to modify the applied torque command, the system may proceed to step 412.

[0041] Step 410 includes the system generating one or more baseline torque commands corresponding to one or more motors. In some embodiments, the system generates a torque command for each motor. In some embodiments, the system generates a torque command for each phase of each motor. For illustration, in some embodiments, the system determines that no modification is needed at step 408, and at step 410, the system generates a torque command equal to the desired torque value for each motor from step 406 (e.g., this torque value may be the same but does not have to be the same).

[0042] Step 412 includes the system generating one or more modified torque commands corresponding to one or more motors. In some embodiments, step 412 may include sending the torque command to power electronics of a motor driver (e.g., motor driver 350). In some embodiments, step 412 includes sending or otherwise inputting the torque command to a motor controller (e.g., a PID controller, a feedforward controller) as input for controlling the position, speed, torque, or combinations thereof of the motors. In some embodiments, the system generates the modified torque command based on a baseline torque value and based on the modification. In some embodiments, for example, the system determines a torque schedule with time characteristics configured to avoid overheating of each motor while providing an effective torque value equal to the desired torque value. For example, the torque schedule may include pulses, peaks, or other features exceeding the effective value, and valleys, minimum points, or other regions below the effective value. In another example, the system may determine a baseline torque value and modulate the baseline value with pulses, peaks, waves, or other features to increase the effective torque value within an extended time period without exceeding torque limits.

[0043] As shown in subplot 450, the system can apply a torque plan. In subplot 450, the horizontal axis indicates time (e.g., time, sample index), and the vertical axis indicates torque. For illustration, referring to subplot 450, the system can determine a desired torque value corresponding to torque plan 451, which may coincide with the torque limit indicated by E. The system can determine to apply torque plan 452 to prevent prolonged operation at the torque limit. As shown, the system can generate a torque plan with a baseline value indicated by D and modulation including pulses with a peak value indicated by F. The effective torque value of torque plan 452 is equivalent to torque plan 451, but can limit the motor's sensitivity to overheating. In some embodiments, the peak value F is determined to cause the motor to increment in position, resulting in a non-zero motor speed (e.g., effective speed or average speed) and thus a potential increase in the torque limit. For illustration, the peak of torque plan 452 may just reach or exceed the value F, which may cause the motor to increment to the next motor phase or other suitable increment. Because the torque schedule then decreases to the baseline value indicated by D, the increments are small (e.g., a few degrees or less of wheel movement). Incremental motion can help distribute the cooling load between phases, but it alters the current demand in each phase so that the current in any one phase does not remain at a large value relative to the other phases over a long period. Although shown as peaks and baselines in diagram 450, the system can generate any suitable torque schedule. For example, the system can modulate the baseline signal, generate a signal based on a function, generate a segmented signal, generate any other suitable torque schedule, or any combination thereof. In some cases, process 400 allows the system to avoid motor overheating by modifying the torque schedule input to the motor controller without modifying the feedback motor controller. To illustrate, a PID controller can be used to control motor position and speed, rather than modifying the controller; process 400 allows modification of the controller input to improve torque limits at low speeds or stall.

[0044] Figure 5 A flowchart illustrating an exemplary process 500 for managing wheel torque based on reference information according to some embodiments of the present disclosure is shown. For illustration, in some embodiments, process 500 may use... Figure 3 The system 300 is used to implement this. It should be understood that, according to some embodiments of this disclosure, processes 400 and 500 can be combined in any suitable manner.

[0045] At step 502, the system receives the desired torque value. In some embodiments, the desired torque value is determined based on operator input (e.g., at operator input interface 310). In some embodiments, the vehicle may include multiple motors, and the system may determine the desired torque value for each motor based on the received desired torque value. For example, the system may implement torque vectorization to provide more torque to specific wheels (e.g., front wheels, rear wheels, wheels with a higher coefficient of friction with the ground) and may receive desired torque commands from a torque control module. In some embodiments, the system receives the desired torque value at a specific frequency (or period) in response to an event (e.g., sampling time), any other suitable regular or irregular interval, or any combination thereof. For example, the system may update or latch the desired torque value at any suitable frequency or interval. To illustrate, an operator may depress the accelerator pedal of the vehicle, and the system may determine the desired torque value based on pedal actuation.

[0046] At step 504, the system determines whether to generate a modified torque command. In some embodiments, the system compares the desired torque command with reference information 550 to determine whether to generate a modified torque command. In some embodiments, reference information 550 may include... Figure 3 Reference information 315 may contain any exemplary information and may be stored in memory (e.g., Figure 3 The system stores the torque command in memory 322. In some embodiments, the system determines whether to generate a modified torque command based on the desired torque, torque limit, operating range, any other suitable criterion, or any combination thereof. In some embodiments, the system compares the desired torque value with the torque limit of each motor and then determines whether to modify the applied torque command based on that comparison. In some embodiments, the system compares the received desired torque value with the torque limit of each motor, and if the desired torque value exceeds the torque limit, the system determines to apply a modification. In some embodiments, the system may access reference information (e.g., reference information 550), which may contain lookup tables, function maps, or any other suitable algorithm for determining whether to modify the torque command. If the system determines not to modify the applied torque command, the system may proceed to step 508 (e.g., generating a torque command based on the desired value without modification). If the system determines to generate a modified torque command, the system may proceed to step 506.

[0047] At step 506, the system retrieves or otherwise accesses reference information. In some embodiments, steps 504 and 506 may be combined into a single step, wherein information from reference information 550 is used to determine whether a modified torque command is generated and the generation of the torque command itself. In some embodiments, reference information 550 may be stored in the system's memory. In some embodiments, reference information 550 may include lookup tables, function maps, limits (e.g., current limits, torque limits, temperature limits, speed limits), thresholds or ranges (e.g., operating range), algorithms or other computer-implemented instructions, any other suitable information, or any combination thereof.

[0048] At step 508, the system generates a torque command based on the reference information from step 506. In some embodiments, the system implements a predetermined algorithm to generate the torque command based on stored computer instructions. The torque command may include a constant value or may be based on a torque schedule having a peak value determined based on a desired torque value.

[0049] As shown in the figure, in some embodiments, steps 506, 508, or both may include any or all of steps 520 through 523. At step 520, the system determines one or more baseline torque values. At step 521, the system determines one or more modifications. At step 522, the system determines one or more torque plans. At step 523, the system determines one or more parameters for generating a torque command. For example, the system may identify one or more modifications (which may include one or more peak shapes, waveforms, pulses, or any other suitable shapes) at step 521 and determine a baseline value at step 520 that, when combined with the modification at step 522, produces an effective torque value (e.g., a time average, a sample average, an RMS value). In another example, the system may determine a modification at step 521 and then determine one or more parameters (such as peak height, peak duration, frequency, or any other suitable parameter) at step 523.

[0050] At step 510, the system applies a torque command. In some embodiments, at step 510, the system generates a control signal based on the torque command. For example, in some embodiments, the system inputs the torque command into a motor controller, which then generates a control signal for applying current to one or more electric motors. In another example, the system may generate and send a control signal indicative of the torque command itself, instead of inputting the torque command into a separate controller. In some embodiments, the system may send control signals to power electronics to cause current to flow in one or more phases of each motor. In some embodiments, the power electronics may include an H-bridge, a half-bridge, or a combination thereof. In some embodiments, the control signal may include a PWM signal, a PDM signal, an analog signal, a series of pulses, waves, modulated waves, digital signals (e.g., serial or parallel signals), any other suitable signal, or any combination thereof. In some embodiments, step 510 may include generating a communication signal and sending the communication signal to the motor driver via a communication interface. For illustration, step 510 may include (e.g., via PWM activation) connecting a phase lead to a phase of the electric motor to a bus lead for a period of time.

[0051] At step 512, the system determines whether to adjust the operating scheme. For example, when a torque command is applied and the wheel's angular position increases, the desired torque changes, or a combination thereof, the system may determine whether to continue applying the torque command in the same manner or whether to re-evaluate and modify the torque command. In some embodiments, the system receives one or more sensor signals at step 512 to determine whether to adjust the operating scheme. In some embodiments, the system may continue applying the torque command generated at 510 until the system decides to adjust the operating scheme. The system may select between the modified and unmodified torque command based on any suitable criteria.

[0052] Figures 6 to 9 An exemplary torque scheme applicable to motors in electric vehicles is shown. For example, Figures 6 to 9 An example torque scheme can be found in Figure 4 Process 400 or Figure 5 The process is generated during step 500. In another example, Figures 6 to 9 The exemplary torque scheme can be derived from Figure 3 System 300 (e.g., generated when implementing process 400, process 500, any other suitable process, or a combination thereof) is generated. In another example, Figures 6 to 9 The exemplary torque scheme can be used to control Figure 1 Vehicle 100 or Figure 2 The vehicle has a torque of 200.

[0053] Figure 6A graph 600 illustrates an exemplary torque scheme below the continuous stall torque limit for a multi-motor system according to some embodiments of the present disclosure. As shown in graph 600, the torque is presented as a function of the time corresponding to four motors: left front (FL), right front (FR), left rear (RL), and right rear (RR). For example, the motors specified by FL, FR, RL, and RR may correspond to... Figure 2 Motor assemblies 201, 202, 203, and 204. As shown in graph 600, for each motor, normalized in any suitable manner, the horizontal axis is in units of time (e.g., not shown in graph 600), and the vertical axis is in units of torque (e.g., Nm or other suitable units). In graph 600, “A” corresponds to the motor’s first torque command, “L1” refers to the motor’s stall torque capacity, “L2” refers to the motor’s near-stall torque capacity, and “S” refers to the wheel slip torque (e.g., which may depend on the characteristics of the ground and tires).

[0054] like Figure 6 As shown, the system requests a torque command A for each wheel. Because the torque command A is less than the stall torque capacity L1 (e.g., the maximum torque capacity at zero speed), the system (e.g., via each respective electric motor of each respective motor assembly) applies a constant torque command to each wheel. In some embodiments, when the torque command is less than L1, the torque plan includes a constant torque value evenly distributed across all motors. In some cases, a constant torque may be applied to each motor, but the torques need not be identical (e.g., in cases where one or more motors are provided with more or less torque in torque vectorization). As shown, for illustrative purposes, the torque values ​​for each motor in graph 600 are slightly different, but in some cases, the requested torque may be the same or comparable for each motor. Figure 6 The changes are more pronounced.

[0055] Figure 7A graph 700 illustrating an exemplary torque schedule for a multi-motor system at or near the continuous stall torque limit according to some embodiments of this disclosure is shown. As shown in graph 700, and similar to graph 600, torque is presented as a function of time for four motors (e.g., corresponding to FL, FR, RL, and RR). As shown in graph 700, for each motor, normalized in any suitable manner, the horizontal axis is in units of time (e.g., with any suitable scale), and the vertical axis is in units of torque (e.g., Nm). In graph 700, similar to graph 600, “A” corresponds to the first torque command of the motor, “L1” refers to the stall torque capacity of the motor, “L2” refers to the near-stall torque capacity of the motor, and “S” refers to the wheel slip torque (e.g., which may depend on the characteristics of the ground and tires). When the desired torque increases to near or beyond the torque limit, the system can determine to modify the torque schedule from a constant value to a modified value.

[0056] For example, if one or more motors have been thermally derated to their continuous condition limits and the vehicle is in a stall state, the system can modify the torque command to accommodate those limits. In some implementations, the torque command can be enhanced if the operator requests motor torque close to the continuous stall torque limit. For example, as shown in graph 700, the average torque at each motor is no greater than the continuous stall rating, as shown in line 710. In the context of graph 700, the system has generated a modified torque command for each motor, which includes a baseline torque value modulated with a triangular peak, as shown. In some implementations, the characteristic frequency of the peak appears at a frequency much higher than the vehicle's inherent frequency response to any type of body movement (e.g., and can also be customized to minimize noise and vibration). For example, the system can determine the modulation frequency to avoid triggering patterns in the vehicle (e.g., to prevent or mitigate operator perception of the modulation).

[0057] As shown in the figure, the torque program for each motor includes a peak (e.g., a triangular peak as shown, but any suitable modulation can be used). As shown, the peak value is approximately equal to the wheel slip torque, at which the wheel begins to move by overcoming friction. In some embodiments, the peak torque of the torque program is selected to achieve very small wheel movement, allowing each motor to move only to the next phase. Depending on the gear ratio (e.g., from motor to wheel), the incremental motion can be as little as a few degrees of wheel rotation. For example, a 30° rotation of the motor and a 10 / 1 gear reduction will produce a 3° wheel rotation (e.g., approximately 1.3 cm for a 0.5 m diameter wheel). In some embodiments, a lower value of the torque program (e.g., a torque valley) is adjusted to ensure that the average torque output meets the operator's request (e.g., the desired torque) without overheating due to stall torque limitations (e.g., stall torque rating or capacity).

[0058] Referring to both graphs 600 and 700, when the torque command increases from a value below the stall torque limit (e.g., within a predetermined operating range) to a value approaching or exceeding the stall torque limit (e.g., approaching or exceeding a predetermined operating range), the system can determine to modify the torque command. As shown, the system applies modulation (e.g., pulses, such as triangular pulses) to a baseline signal (e.g., a lower, flat torque value, as shown). In some embodiments, the system does not need to modulate the baseline signal and can generate a torque schedule with a predetermined shape (e.g., scaled, offset, or otherwise customized to generate an average value corresponding to the torque command).

[0059] Figure 8A graph 800 illustrating an exemplary torque schedule for a multi-motor system according to some embodiments of the present disclosure is shown, which exhibits an increasing torque value in the presence of some increments. As shown in graph 800, and similar to graphs 600 and 700, torque is shown as a function of time for four motors (e.g., corresponding to FL, FR, RL, and RR). As shown in graph 800, for each motor, normalized in a suitable manner, the horizontal axis is in units of time, and the vertical axis is in units of torque (e.g., Nm). In graph 800, similar to graphs 600 and 700, “A” corresponds to the first torque command of the motor, “L1” refers to the stall torque capacity of the motor, “L2” refers to the near-stall torque capacity of the motor, and “S” refers to the wheel slip torque (e.g., which may depend on the characteristics of the ground and tires). When the desired torque increase exceeds the stall torque limit, the system can determine a modified torque schedule by increasing the average or effective torque value. In some cases, due to the effective small amount of motion (e.g., low speed), the incremental motion of the motor can correspond to an increase in the torque limit. For example, because the motor can move incrementally, the current load, and therefore the cooling load, can change and thus be more evenly distributed between phases. This allows for commanding higher torque because the current in each phase changes over time.

[0060] refer to Figure 7 As shown in graph 700, incremental wheel movement can be caused by a modulated torque command. Because incremental wheel movement is achieved, the operator's request for a torque command greater than the stall rating of each motor can be satisfied while the vehicle is still in or very close to a stall condition. The torque rating of each motor can be increased due to the incremental movement (e.g., from L1 to L2), and thus a larger average torque value can be achieved without the motors overheating, as shown in graph 800. As shown, in some embodiments, the torque trough (e.g., the value of the minimum torque value in the torque program) increases, while the maximum torque command value remains at the wheel slip torque S. Therefore, the wheels can be supplied with increased torque, but only incremental slippage will occur. In some embodiments, to achieve a larger average torque value without causing more than incremental slippage, one or more peaks in the torque can be widened (e.g., pulse width modulation), the shape or profile in the torque program can be modified, a new type of torque program can be selected, the pulse density can be increased (e.g., more peaks per duration), any other suitable modifications can be made to the torque program, or any combination thereof can be applied.

[0061] In some implementations, the system can use torque planning to help support traction and wheel slip control systems. For example, the surface friction coefficient can be calculated or otherwise estimated from torque measured during wheel slippage. This information can be used by the system to improve response time, performance, and operator experience by modifying torque commands based at least in part on wheel slippage torque, friction coefficient, or both. For example, stall torque limits can be stored in memory (e.g., as a function or as a reference database indexed by speed).

[0062] In the exemplary example, only for the sake of Figures 6 to 8 For the purposes of illustration in the context of this example, A may correspond to 50 Nm, L1 to 60 Nm, L2 to 90 Nm, and S to 200 Nm. Based on these exemplary values, any torque request below 50 Nm may exhibit a relatively constant torque schedule over time (e.g., unmodulated). The system may identify the desired torque and then determine whether to modulate the torque request based on a function, a reference table, any other suitable reference information, or any combination thereof. In this example, if the torque command is 50 Nm, the system does not need to adjust, modify, or modulate the torque command because the desired torque is less than the stall torque limit, and the motor is unlikely to overheat (e.g., shown in graph 600). When the torque command increases to, for example, 60 Nm, the system may modify the torque schedule to achieve the desired torque value of 60 Nm while allowing only incremental rotation of the motor by achieving a wheel slip torque of 200 Nm at the peak torque value. In this example, the motor's torque capacity can be increased to 90 Nm as the motor performs some incremental motion, which allows for higher torque commands to be achieved by further modifying the torque schedule (e.g., by raising the torque trough while keeping the torque peak at the "S" value as needed).

[0063] Figure 9 An exemplary torque scheme for a motor is illustrated according to some embodiments of this disclosure. The torque scheme may include any suitable time or otherwise ordered set of torque values ​​for influencing the torque generated by one or more motors. The torque scheme may include a single value (e.g., a single time torque value, a constant value over time), a set of torque values ​​(e.g., an array, vector, matrix, sequence of values), a set of torque and time values ​​(e.g., a torque-time function, a set of time torque values, a set of torque exponential values ​​(e.g., sequential torque values), a function having one or more predetermined values ​​(e.g., coefficients, offsets, any other parameters), any other suitable set of one or more values, or any combination thereof. Any exemplary torque scheme, its parameters or aspects thereof, and any other suitable features shown in sub-figures 900 to 950 may be combined or otherwise used in conjunction to manage torque at one or more wheels of a vehicle. The effective torque values ​​in each sub-figure are shown by dashed lines.

[0064] Sub-figure 900 illustrates a torque schedule including a square wave and an offset. For example, the torque schedule shown in sub-figure 900 may include a modified torque command (e.g., corresponding to one or more motors) comprising a modification (e.g., a square wave) and a baseline torque command (e.g., a minimum, average, or some other suitable value of the modified square wave). For illustration, an unmodified square wave may include an offset added to generate a zero average value of the modified torque command, or an unmodified square wave may include an offset added to generate a zero minimum value of the modified torque command. In either case, the offset may correspond to the baseline torque command, and the square wave may correspond to the modification. In some embodiments, the torque schedule may be parameterized by an offset value, frequency (e.g., or period), duty cycle, amplitude, any other suitable parameter affecting the shape and value of the torque command, or any combination thereof. The system may select, modify, or otherwise use any or all of these parameters to generate a torque schedule corresponding to the torque command. For example, the system may select a square wave with a characteristic average value (e.g., or any suitable shape) and add an offset to the square wave to achieve a desired average value (e.g., the torque command). In some implementations, the system may select, change, or otherwise control the frequency to avoid resonance, excite vibration modes (e.g., vehicle body, suspension system), or both, thereby reducing the operator's perception of any incremental motion.

[0065] Sub-figure 910 illustrates a torque schedule without offset. For example, the torque schedule shown in sub-figure 910 may include a modified torque command (e.g., corresponding to one or more motors) comprising a modification (e.g., a modified amplitude) and a baseline torque command (e.g., an unmodified square wave). For illustration, the unmodified square wave may include a non-zero average value that generates the modified torque command when scaled by modifying the amplitude. In some embodiments, the torque schedule may be parameterized by frequency (e.g., or period), duty cycle, amplitude, any other suitable parameter affecting the shape and value of the torque command, or any combination thereof. The system may select, modify, or otherwise use any or all of these parameters to generate a torque schedule corresponding to the torque command. For example, the system may select a square wave (e.g., or any suitable shape) and scale the amplitude of the square wave to achieve a desired average value (e.g., the torque command). In some embodiments, the torque schedule includes a zero or near-zero minimum value (e.g., this minimum value may correspond to, but does not need to correspond to, a zero-current condition).

[0066] Sub-figure 920 illustrates a torque schedule including a triangular wave. For example, the torque schedule shown in sub-figure 910 may include a modified torque command (e.g., corresponding to one or more motors) comprising a baseline torque command (e.g., and an offset) and a modification (e.g., a triangular wave). For illustration, the unmodified triangular wave may include a non-zero average value that generates the modified torque command when scaled by modifying the amplitude. For further illustration, the unmodified triangular wave may include a zero average value, which is then offset to generate a modified torque command with a desired average value. In some embodiments, the torque schedule may be parameterized by frequency (e.g., or period), duty cycle, amplitude, shape type, any other suitable parameter affecting the shape and value of the torque command, or any combination thereof. The system may select, modify, or otherwise use any or all of these parameters to generate a torque schedule corresponding to the torque command. For example, the system may select a triangular wave with a characteristic average value (e.g., forward or backward sawtooth or any suitable shape) and add an offset to a square wave to achieve the desired average value (e.g., the torque command). In some embodiments, the torque program includes a series of repeating peaks having any suitable shape (e.g., square, triangle, sine, piecewise function, polynomial, or a combination thereof). In some embodiments, the torque program may include peaks with flat portions preceding and / or following the peaks, wherein the flat portions are shorter than, equal to, or longer than the duration of the peaks. For example, as shown in Figure 920, the duration of a triangular peak and the duration of the intermediate flat portion between the peaks are approximately equal.

[0067] Subplot 930 illustrates the transitions between torque plans. As shown, the system employs a torque plan equal to the torque command (e.g., unmodulated but not necessarily constant), followed by a square wave with offset, and then a triangular wave. For example, subplot 930 could correspond to a situation where the desired torque is initially below the stall torque limit, then increases to exceed the stall torque limit, and then the torque plan is modified in shape. The square and triangular waves can be scaled by modifying their amplitudes, offsetting from zero, or both, to produce the desired average value.

[0068] Figure 940 illustrates a torque scheme with peaks exhibiting density variations. In some embodiments, the system may apply a pulse-displacement mechanism (PDM) to alter the applied effective torque. In some embodiments, each pulse or peak is similarly shaped, but the frequency of occurrence is varied to change the applied effective torque. For example, as shown, a reduced pulse density produces a smaller torque command. Pulses may include pulse waveforms that are scaled, offset, or both to produce a desired pulse shape. For example, a baseline signal may correspond to an offset, and scaled and / or offset pulses are added to that offset to produce a modified torque command.

[0069] Figure 950 illustrates a torque scheme with peaks exhibiting varying widths. In some implementations, the system may apply PWM to alter the applied effective torque. In some implementations, the duration of each pulse or peak is varied to change the applied effective torque. For example, as shown, a reduced pulse width produces a smaller torque command. Pulses may include pulse waveforms that are scaled, offset, or both to produce a desired pulse shape. For example, a baseline signal may correspond to an offset and / or width, to which scaling and / or offset are added to produce a modified torque command.

[0070] The foregoing description is merely illustrative of the principles of this disclosure, and various modifications can be made by those skilled in the art without departing from the scope of this disclosure. The above embodiments are presented for illustrative purposes and not for limitation. This disclosure may also take many forms other than those expressly described herein. Therefore, it should be emphasized that this disclosure is not limited to the methods, systems, and apparatus expressly disclosed, but is intended to include variations and modifications thereof within the spirit of the appended claims.

Claims

1. A method for managing motor torque in a vehicle having multiple motors, the method comprising: Determine the amount of velocity loss corresponding to the motor speed; The torque limit is determined based on the aforementioned velocity loss. Determine the desired torque value; The decision to generate a modification to multiple baseline torque commands is based on the desired torque value and the torque limit, and if the desired torque value is close to or exceeds the torque limit, the decision to generate a modification to multiple baseline torque commands is based on the possibility of motor overheating. If the baseline torque command is not modified, then the multiple baseline torque commands corresponding to multiple motors are generated; as well as If the baseline torque is modified, then based on the modification and based on the plurality of baseline torque commands, a plurality of modified torque commands corresponding to the plurality of motors are generated, wherein the effective torque value of the modified torque command is equal to the desired torque value, and the phase of the modified torque command corresponding to each motor is different.

2. The method of claim 1, wherein generating the plurality of modified torque commands comprises: Search for reference information; Determine the baseline torque command; The baseline torque command is modified based on the reference information to generate the modified torque command; as well as The modified torque command is sent to the power electronics system connected to the plurality of motors.

3. The method of claim 1, wherein the modified torque command comprises: Baseline torque command; and A wave consisting of at least one of the following: square wave, pulse-modulated wave, pulse density wave, sawtooth wave, triangular wave, sine wave, or piecewise function wave.

4. The method of claim 1, wherein determining whether to generate the modification to the plurality of baseline torque commands comprises: Determine the reference operating range; as well as Determine whether the stall velocity and the desired torque value are within the reference operating range.

5. The method of claim 1, wherein the plurality of modified torque commands include a time average indicating the desired torque value.

6. The method of claim 1, further comprising retrieving reference information based on the stall velocity, wherein the reference information includes the torque limit.

7. The method of claim 1, wherein determining the desired torque value includes receiving input indicating the desired torque value from an operator input interface.

8. The method according to claim 1, further comprising: Determine a peak torque command corresponding to the wheel slip torque, wherein the peak value of the plurality of modified torque commands corresponds to the peak torque command; as well as Based on the torque command, at least one of the plurality of motors is incremented in angular position.

9. The method of claim 1, wherein each of the plurality of modified torque commands comprises: Minimum value, which is less than the torque limit; and The maximum value corresponds to the wheel slippage torque.

10. A method for managing motor torque in a vehicle having multiple motors, the method comprising: For each of the multiple motors, the operating range is identified based on the rotational speed and the desired torque value; Retrieve the reference operating range from memory; The torque command mode is determined based on the operating range and the reference operating range, and the torque command mode is determined based on the possibility of motor overheating when the operating range is close to or exceeds the reference operating range. If the operating range is within the reference operating range, then the first torque command mode is applied; as well as If the operating range is not within the reference operating range, a second torque command mode is applied, wherein the second torque command includes a baseline command and modulation, wherein the effective torque value of the second torque command is equal to the desired torque value, and the phase of the second torque command is different for each motor.

11. A system for managing motor torque in a vehicle having multiple motors, the system comprising: A sensor configured to sense the motor speed of a plurality of motors; and A control circuit, connected to the sensor and configured to: Determine the amount of velocity loss corresponding to the motor speed; The torque limit is determined based on the aforementioned velocity loss. Determine the desired torque value; The decision to generate a modification to multiple baseline torque commands is based on the desired torque value and the torque limit, and if the desired torque value is close to or exceeds the torque limit, the decision to generate a modification to multiple baseline torque commands is based on the possibility of motor overheating. If the baseline torque command is not modified, then the multiple baseline torque commands corresponding to multiple motors are generated; as well as If the baseline torque is modified, then based on the modification and based on the plurality of baseline torque commands, a plurality of modified torque commands corresponding to the plurality of motors are generated, wherein the effective torque value of the modified torque command is equal to the desired torque value, and the phase of the modified torque command corresponding to each motor is different.

12. The system of claim 11, further comprising a power electronic system connected to the control circuit and the plurality of motors.

13. The system of claim 12, wherein generating the plurality of modified torque commands comprises: Search for reference information; Determine the baseline torque command; as well as The baseline torque command is modified based on the reference information to generate the modified torque command; as well as The modified torque command is sent to the power electronics system.

14. The system of claim 11, wherein the modified torque command comprises: Baseline torque command; and A wave consisting of at least one of the following: square wave, pulse-modulated wave, pulse density wave, sawtooth wave, triangular wave, sine wave, or piecewise function wave.

15. The system of claim 11, wherein the control circuitry is configured to determine whether to generate the modification to the plurality of baseline torque commands by means of the following steps: Determine the reference operating range; and Determine whether the stall velocity and the desired torque value are within the reference operating range.

16. The system of claim 11, wherein the plurality of modified torque commands include a time average indicating the desired torque value.

17. The system of claim 11, wherein the control circuit is further configured to retrieve reference information based on the stall velocity, wherein the reference information includes the torque limit.

18. The system of claim 11, wherein the control circuit is configured to determine the desired torque value by receiving an input indicating the desired torque value from an operator input interface.

19. The system of claim 11, wherein the control circuit is further configured to: Determine a peak torque command corresponding to the wheel slippage torque, wherein the peak value of the plurality of modified torque commands corresponds to the peak torque command; and Based on the torque command, at least one of the plurality of motors is incremented in angular position.

20. The system of claim 11, wherein each of the plurality of modified torque commands comprises: Minimum value, which is less than the torque limit; and The maximum value corresponds to the wheel slippage torque.

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