Thermal Stall Protection for Force Feedback Actuators

Abstract

A method includes: receiving motor speed data, and in response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculating a thermal metric corresponding to a phase imbalance of the motor; identifying at least one thermal mitigation parameter based on the thermal metric; generating at least one thermal management motor position command based on the at least one thermal mitigation parameter; and selectively controlling the motor according to the thermal management motor position command.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Patent Application Serial No. 63 / 212,243 filed on June 18, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a vehicle steering system, and more particularly, to a stall thermal protection system and method for a force feedback actuator of a vehicle steering system. Background Art

[0004] A vehicle such as an automobile, truck, sport utility vehicle, crossover, minivan, ship, aircraft, all-terrain vehicle, recreational vehicle, or other suitable vehicle includes a steering system, such as an electric power steering (EPS) system, a steer-by-wire (SbW) system, or other suitable steering system. In an SbW system, a steering wheel actuator may be employed to receive driver steering input and provide feedback force. The steering wheel actuator may include a controller, an electric motor, and a mechanism for converting motor shaft torque to steering wheel torque. The feedback force is typically provided by applying torque in a direction opposite to the intended motion (e.g., to simulate a rack force that would otherwise be displaced by a pinion).

[0005] Typically, in EPS systems, rack end-of-travel stops limit the range of motion, thus providing a mechanical travel stop for the steering wheel. Since there is no mechanical connection in an SbW system, a steering wheel actuator is used to provide a software travel stop (e.g., called a soft stop) for the steering wheel. This is typically accomplished by increasing the feedback force to a high value as the driver approaches the end-of-travel position. Summary of the invention

[0006] The present disclosure generally relates to vehicle steering systems.

[0007] One aspect of the disclosed embodiment includes a method for preventing a motor from operating at a motor position with unbalanced phase currents. The method includes: receiving motor speed data, and in response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculating a thermal metric corresponding to a phase imbalance of the motor; identifying at least one thermal mitigation parameter based on the thermal metric; generating at least one thermally managed motor position command based on the at least one thermal mitigation parameter; and selectively controlling the motor according to the thermally managed motor position command.

[0008] Another aspect of the disclosed embodiment includes a system for preventing a motor from operating in a motor position with unbalanced phase current. The system includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive motor speed data, and, in response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculate a thermal metric corresponding to a phase imbalance of the motor; identify at least one thermal mitigation parameter based on the thermal metric; generate at least one thermal management motor position command based on the at least one thermal mitigation parameter; and selectively control the motor according to the thermal management motor position command.

[0009] Another aspect of the disclosed embodiment includes a device for preventing a motor from operating in a motor position with an unbalanced phase current. The device includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive motor speed data; and in response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculate a thermal metric corresponding to a phase imbalance of the motor; use at least one lookup table associated with the thermal metric to identify at least one thermal mitigation parameter based on the thermal metric; generate at least one thermal management motor position command based on the at least one thermal mitigation parameter; modify the thermal management motor position command by combining the thermal management motor position command with a measured steering wheel position; and selectively control the motor according to the modified thermal management motor position command.

[0010] These and other aspects of the disclosure are disclosed in the following detailed description of the embodiments, the appended claims and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present disclosure is best understood by the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not drawn to scale. Instead, the sizes of the various features are arbitrarily expanded or reduced for clarity.

[0012] Figure 1 A vehicle in accordance with the principles of the present disclosure is generally shown.

[0013] Figure 2 A vehicle controller system including a controller according to the principles of the present disclosure is generally shown.

[0014] Figure 3 is a current diagram of a three-phase system according to the principles of the present disclosure.

[0015] Figure 4 is a graph showing the effect of unbalanced phase current on temperature rise without mitigation according to the principles of the present disclosure.

[0016] Figure 5 An end-of-trip thermal management system according to the principles of the present disclosure is generally shown.

[0017] Figure 6 A thermal management position tracking and torque command overlay method according to the principles of the present disclosure is generally shown.

[0018] Figure 7 A thermal condition monitoring method according to the principles of the present disclosure is generally shown.

[0019] Figure 8 An alternative thermal condition monitoring method according to the principles of the present disclosure is generally shown.

[0020] Fig. 9 A thermal management motor position command generation method according to the principles of the present disclosure is generally presented.

[0021] Fig.10 An alternative thermal management motor position command generation method according to the principles of the present disclosure is generally presented.

[0022] Fig.11 is a graph showing the effect of unbalanced phase current on temperature rise with mitigation according to the principles of the present disclosure.

[0023] Fig.12 is a flow chart generally illustrating a thermal mitigation method according to the principles of the present disclosure. DETAILED DESCRIPTION

[0024] The following discussion is directed to various embodiments of the present disclosure. Although one or more of these embodiments may be preferred, the disclosed embodiments should not be interpreted or otherwise used as limiting the scope of the present disclosure, including the claims. In addition, it will be understood by those skilled in the art that the following description has a wide range of applications, and the discussion of any embodiment is intended only to be an exemplary discussion of that embodiment, and is not intended to imply that the scope of the present disclosure, including the claims, is limited to that embodiment.

[0025] As described, a vehicle such as an automobile, truck, sport utility vehicle, crossover, minivan, ship, aircraft, all-terrain vehicle, recreational vehicle, or other suitable vehicle includes a steering system, such as an EPS system, an SbW system, or other suitable steering system. In an SbW system, a steering wheel actuator can be used to receive driver steering input and provide feedback force. The steering wheel actuator can include a controller, an electric motor, and a mechanism for converting motor shaft torque to steering wheel torque. The feedback force is provided by applying torque in a direction opposite to the intended motion (e.g., to simulate a rack force that would otherwise be converted through a pinion).

[0026] Typically, in EPS systems, rack end-of-travel stops limit the range of motion, thus providing a mechanical travel stop for the steering wheel. Since there is no mechanical connection in an SbW system, a steering wheel actuator is used to provide a software travel stop (e.g., called a soft stop) for the steering wheel. This is typically accomplished by increasing the feedback force to a high value as the driver approaches the end-of-travel position.

[0027] When held at end of travel, the steering wheel actuator motor may be at or near a stall condition (e.g., 0 motor radians per second) while providing a high level of torque. This may result in high motor phase currents. Depending on the electrical position of the motor during end of travel hold, the phase currents may be unbalanced, which may result in higher power dissipation on one or more phases. Figure 3 shows roughly the range of power dissipation per phase over one electrical revolution, Figure 4 Generally shows that when the rotor is kept Figure 3 An imbalance in the temperature rise that can occur when the power is at the position shown in . This can result in 66.6% of the power being dissipated through a single phase, while the other two phases only dissipate 33.3% of the power. This imbalance results in an increased temperature rise on the phase that dissipates the most power.

[0028] Typically, to address the temperature increase, such systems rely on hardware designed to withstand the temperature increase caused by unbalanced power dissipation. This can result in higher costs and larger packaging space. It may also require the use of challenging manufacturing processes such as packaging or other heat transfer methods.

[0029] Therefore, it may be desirable to have systems and methods such as those described herein that are configured to prevent high power dissipation in a single phase and instead spread the power dissipation among the phases during end-of-trip hold. In some embodiments, the systems and methods described herein can be configured to allow for more optimized hardware design for packaging, lower cost, and avoidance of challenging manufacturing.

[0030] In some embodiments, the systems and methods described herein can be configured to provide a thermal management strategy to improve the power dissipation distribution among motor and / or controller phases during an end-of-travel hold event. The systems and methods described herein can be configured to prevent prolonged operation in a motor position with unbalanced phase currents by modifying system behavior based on sensor inputs and predetermined parameters (e.g., which can result in more balanced power dissipation and relatively smaller temperature increases).

[0031] In some embodiments, the systems and methods described herein can be configured to provide end-of-travel thermal management, such as Figure 5 and Figure 6As generally shown in , the end-of-travel thermal management may include thermal condition monitoring, position command generation, position tracking control, motor torque command blending, etc. The systems and methods described herein may be configured to determine a level of thermal mitigation by monitoring a condition of the steering system.

[0032] For example, Figure 5 As generally shown in FIG. 1 , the systems and methods described herein may be configured to generate one or more steering wheel torque commands (eg, using one or more torque estimates (T r,est )). The systems and methods described herein may be configured to use the sensed steering wheel torque (T h,meas ) generates one or more steering wheel torque estimates (T h,est The systems and methods described herein may be configured to use a steering wheel torque tracking controller to provide a torque tracking controller based on at least one torque command and one or more steering wheel torque estimates (T h,est ) to generate the steering wheel torque tracking output.

[0033] The systems and methods described herein may be configured to provide thermal management and provide motor torque command blending. The systems and methods described herein may be configured to generate a blended torque command (T m,cmd ). The systems and methods described herein can be configured to provide motor torque control. For example, the systems and methods described herein can be configured to generate a voltage command (V abc,cmd The systems and methods described herein may be configured to provide pulse width modulation to the voltage command. The systems and methods described herein may be configured to use an inverter to generate a motor voltage (V abc ). The systems and methods described herein may be configured to provide a motor voltage to a motor.

[0034] The systems and methods described herein may be configured to use motor torque (T e ) generates mechanical steering wheel torque (T h The systems and methods described herein may be configured to use motor position (θ m ) to measure the motor position (θ m , meas). The systems and methods described herein may be configured to use the motor position (θ m ,meas) to estimate the motor speed. The systems and methods described herein can be configured to use the motor angle (θ a ) and motor position (θ m ,meas) to determine the column (motor) angle estimation result (θ a,est ).

[0035] The systems and methods described herein may be configured to provide a motor current measurement based on a motor speed estimate, a motor current measurement (I abc,meas ) and temperature estimation results (Ω est )(For example, based on the temperature measurement result (Ω meas ) estimate) provide thermal condition monitoring.

[0036] The systems and methods described herein can be configured to provide position command generation based on the output of thermal condition monitoring. The systems and methods described herein can be configured to provide position command generation based on the output of position command generation and column (motor) angle estimation results (θ a,est ) to provide position tracking control.

[0037] like Figure 6 As generally shown in FIG. 1 , the systems and methods described herein may be configured to be based on a position command (θ a,cmd ) provides thermal management position control. The systems and methods described herein can be configured to sum a motor torque command superimposed on a steering wheel actuator base control output (e.g., generated based on rack force estimates associated with the rack actuator and steering wheel torque measurements). The systems and methods described herein can be configured to provide motor torque control based on a motor torque command and a motor angle. The systems and methods described herein can be configured to control mechanical aspects of a steering wheel actuator using motor control torque measurements and driver torque.

[0038] Thermal management position control can be based on Figure 6 is limited, and:

[0039] Steering wheel actuator "base" dynamics:

[0040] θ a =H d T d +H r T r,Est +H m ΔT m,Cmd

[0041] Among them, θ a is the column position, H d is the steering wheel actuator mechanical system transfer function, H r is the basic control transfer function of the steering wheel actuator, H m is the motor torque control transfer function, T d is the driver (e.g., vehicle operator) torque, T r is the rack force estimate (e.g., pinion torque units), ΔT m,Cmd is the thermal management motor torque command.

[0042] Thermal Management Position Control:

[0043]

[0044] in, is the thermal management transfer function, is the basic torque command transfer function, θ a,Est is the column position estimation result, θ a,Cmd is the column position command.

[0045] Generalized closed-loop position tracking dynamics:

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052] Open loop position control:

[0053]

[0054]

[0055] The ideal position tracking can be defined as follows:

[0056]

[0057] In some embodiments, the systems and methods described herein can be configured to perform a primary monitor function by using phase current magnitudes (e.g., which may be referred to herein as peak current estimates). Thermal constraints for SbW system force feedback actuators are dominated by end-of-travel events that occur at or near zero speed. Since the system is in a stalled state during these events, it cannot be assumed that the phase currents are balanced. To avoid the problem of requiring a higher sampling rate relative to a direct quadrature zero representation, the systems and methods described herein can be configured to use separate phase currents at or near zero speed, where the phase currents are most likely to be unbalanced.

[0058] In some embodiments, the systems and methods described herein can be configured to use a direct quadrature zero representation for phase currents above a predetermined speed threshold (e.g., by assuming that the phase currents are balanced). The systems and methods described herein can be configured to employ a calibratable low-pass filter on the input speed signal to avoid rapid transitions. The systems and methods described herein can be configured to process the estimated peak current for each phase via a usage model (e.g., such as those described in U.S. Pat. No. 6,166,502, the contents of which are incorporated herein by reference in their entirety) to determine a usage-based thermal metric.

[0059] In some embodiments, the systems and methods described herein can be configured to calculate a separate thermal metric for each phase, which can allow detection of unbalanced phase currents and / or can prevent premature limiting when phase currents are balanced. The systems and methods described herein can be configured to output a maximum thermal metric for use by downstream functions.

[0060] In some embodiments, Figure 7 and Figure 8 As generally shown in , the systems and methods described herein can be configured to provide thermal condition monitoring. The systems and methods described herein can be configured to use thermal metrics in combination with motor speed to determine when to take thermal mitigation measures. The systems and methods described herein can be configured to not take mitigation measures for phase current speeds below a calibratable speed threshold. The systems and methods described herein can be configured to take mitigation measures for phase current speeds above a calibratable threshold (e.g., which may indicate that the phase current speed is at or near zero, which may correspond to an unbalanced phase current condition).

[0061] In some embodiments, the systems and methods described herein can be configured to use a low pass filter with a calibrable cutoff frequency on the input speed signal to avoid sudden changes in thermal mitigation. When the speed is below a calibrated threshold, the systems and methods described herein can use a lookup table to determine the parameters of thermal mitigation based on the state of the thermal metric.

[0062] The systems and methods described herein can be configured to cause relatively small changes in motor position during end-of-trip hold to avoid long periods of unbalanced phase current. The position changes of the rotor can include sufficient amplitude and frequency to improve the balance of power dissipation between phases, while not being so large as to cause severe dissatisfaction to the driver. In order to minimize the impact on the driver, the systems and methods described herein can be configured to change the amplitude, frequency, and type of rotor position movement according to the state of the thermal metric. For example, if the thermal metric has a moderate value indicating moderate heating, the systems and methods described herein can be configured to use low amplitude and frequency movements to avoid further heating without causing significant interference to the driver. Alternatively, if the thermal metric has a high value indicating significant heating, the systems and methods described herein can be configured to increase the amplitude and frequency of the movement to reduce the peak motor temperature.

[0063] The systems and methods described herein can be configured to use one or more calibratable lookup tables, using a thermal metric (e.g., which can be an independent variable of each lookup table) to identify one or more thermal mitigation parameters, such as thermal mitigation type, thermal amplitude of motion, thermal mitigation frequency, other suitable parameters, or combinations thereof.

[0064] In some embodiments, the thermal mitigation type may define a motion profile to be induced. The motion profile may include at least one of a sinusoidal waveform profile, a trapezoidal waveform profile, a square waveform profile, a step function profile (e.g., (moving to an optimal thermal position)), a non-geometric profile (predetermined profile), or a combination thereof.

[0065] In some embodiments, systems and methods can be configured to cause a thermal magnitude of motion in a motor. The thermal magnitude of motion can be limited to steering wheel angle or motor angle. The range of magnitudes can include any suitable range, for example, 0-30 electric motor degrees or other suitable range, and can represent the amount of motion that provides a completely balanced power dissipation. Additionally or alternatively, if the thermal metric indicates less severe heating, the systems and methods described herein can be configured to use an intermediate value.

[0066] In some embodiments, the thermal mitigation frequency may correspond to the frequency of repeating a specified waveform (eg, having a range of 0.1 Hz to 0.5 Hz or other suitable range).

[0067] In some embodiments, the systems and methods described herein may be configured to generate at least one thermally managed motor position command using one or more thermal mitigation parameters after identifying the one or more thermal mitigation parameters using a lookup table.

[0068] like Fig. 9 and Fig.10As generally shown in FIG. 1 , the systems and methods described herein can be configured to perform thermal management position tracking control. The systems and methods described herein can be configured to use open loop control to generate at least one motor torque command based on a thermal management motor position command. The systems and methods described herein can be configured as follows: Figure 6 As generally shown in FIG. 1 , the at least one motor torque command is summed with a motor torque command from a corresponding base controller.

[0069] In some embodiments, the systems and methods described herein can be configured to provide a position signal superposition by modifying the thermal management motor position command by combining the thermal management motor position command with the measured steering wheel position. The systems and methods described herein can be configured to provide a signal corresponding to the modified thermal management motor position command to a proportional controller for motor torque command generation.

[0070] In some embodiments, the systems and methods described herein may be configured to provide phase voltage modification by directly modifying the phase voltage based on thermal management motor position commands.

[0071] In some embodiments, Fig.11 As generally shown in , the systems and methods described herein can be configured to provide thermal mitigation techniques that can significantly improve peak motor temperature. In some embodiments, the systems and methods described herein can be configured to provide feedback to the driver during execution of the thermal mitigation techniques described herein, such as haptic feedback or other suitable feedback.

[0072] In some embodiments, the systems and methods described herein may be configured to allow torque output to be maintained while still mitigating temperature by manipulating rotor position. Additionally or alternatively, the systems and methods described herein may be configured to calculate thermal metrics for each phase to detect phase imbalance.

[0073] In some embodiments, the systems and methods described herein can be configured to receive motor speed data. The systems and methods described herein can be configured to calculate a thermal measure corresponding to a phase imbalance of the motor in response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed. In some embodiments, the threshold speed can include a calibratable threshold.

[0074] The systems and methods described herein may be configured to identify at least one thermal mitigation parameter based on the thermal metric.In some embodiments, identifying the at least one thermal mitigation parameter based on the thermal metric may include using at least one lookup table associated with the thermal metric.

[0075] The systems and methods described herein may be configured to generate at least one thermal management motor position command based on the at least one thermal mitigation parameter. The systems and methods described herein may be configured to selectively control the motor based on the thermal management motor position command. In some embodiments, selectively controlling the motor based on the thermal management motor position command may include modifying at least one phase voltage of the motor based on the thermal management motor position command.

[0076] In some embodiments, the systems and methods described herein may be configured to use open loop control to generate a motor torque command based on a thermal management motor position command. The systems and methods described herein may be configured to further selectively control the motor based on the motor torque command.

[0077] In some embodiments, the systems and methods described herein can be configured to modify the thermal management motor position command by combining the thermal management motor position command with the measured steering wheel position. The systems and methods described herein can be configured to generate a motor torque command using the modified thermal management motor position command. The systems and methods described herein can be configured to further selectively control the motor based on the motor torque command.

[0078] Figure 1 A vehicle 10 is generally shown in accordance with the principles of the present disclosure. The vehicle 10 may include any suitable vehicle, such as a car, a truck, a sport utility vehicle, a minivan, a crossover, any other passenger vehicle, any suitable commercial vehicle, or any other suitable vehicle. Although the vehicle 10 is illustrated as a passenger vehicle having wheels and used on a road, the principles of the present disclosure may be applied to other vehicles, such as airplanes, ships, trains, drones, or other suitable vehicles.

[0079] The vehicle 10 includes a vehicle body 12 and a hood 14. A passenger compartment 18 is at least partially defined by the vehicle body 12. Another portion of the vehicle body 12 defines an engine compartment 20. The hood 14 may be removably attached to a portion of the vehicle body 12 such that the hood 14 provides access to the engine compartment 20 when the hood 14 is in a first position or an open position and covers the engine compartment 20 when the hood 14 is in a second position or a closed position. In some embodiments, the engine compartment 20 may be disposed at a rear portion of the vehicle 10 (compared to what is generally shown).

[0080] The passenger compartment 18 may be disposed rearward of the engine compartment 20, but in embodiments where the engine compartment 20 is disposed at a rear portion of the vehicle 10, the passenger compartment 18 may be disposed forward of the engine compartment 20. The vehicle 10 may include any suitable propulsion system, including an internal combustion engine, one or more electric motors (e.g., an electric vehicle), one or more fuel cells, a hybrid (e.g., a hybrid vehicle) propulsion system including a combination of an internal combustion engine, one or more electric motors, and / or any other suitable propulsion system.

[0081] In some embodiments, the vehicle 10 may include a gasoline engine or a gasoline fuel engine, such as a spark ignition engine. In some embodiments, the vehicle 10 may include a diesel fuel engine, such as a compression ignition engine. The engine compartment 20 houses and / or surrounds at least some components of the propulsion system of the vehicle 10. Additionally or alternatively, propulsion control devices, such as an accelerator actuator (e.g., an accelerator pedal), a brake actuator (e.g., a brake pedal), a steering wheel, and other such components, are disposed in the passenger compartment 18 of the vehicle 10. The propulsion control devices may be actuated or controlled by a driver of the vehicle 10 and may be directly connected to corresponding components of the propulsion system, such as a throttle, brake, axle, vehicle transmission, etc., respectively. In some embodiments, the propulsion control devices may communicate signals to a vehicle computer (e.g., a drive-by-wire vehicle computer), which in turn may control corresponding propulsion components of the propulsion system. Thus, in some embodiments, the vehicle 10 may be an autonomous vehicle.

[0082] In some embodiments, the vehicle 10 includes a transmission that communicates with the crankshaft via a flywheel or a clutch or a fluid coupling. In some embodiments, the transmission includes a manual transmission. In some embodiments, the transmission includes an automatic transmission. The vehicle 10 may include one or more pistons that, in the case of an internal combustion engine or a hybrid vehicle, operate in conjunction with the crankshaft to generate force that is transmitted through the transmission to one or more shafts, which causes the wheels 22 to rotate. When the vehicle 10 includes one or more electric motors, the vehicle battery and / or fuel cell provides energy to the electric motors to rotate the wheels 22.

[0083] The vehicle 10 may include an automatic vehicle propulsion system, such as cruise control, adaptive cruise control, automatic braking control, other automatic vehicle propulsion systems, or combinations thereof. The vehicle 10 may be an automatic or semi-automatic vehicle, or other suitable type of vehicle. The vehicle 10 may include additional features or fewer features than those generally shown and / or disclosed herein.

[0084] In some embodiments, the vehicle 10 may include an Ethernet component 24, a controller area network (CAN) bus 26, a media oriented system transport component (MOST) 28, a FlexRay component 30 (e.g., a wire control brake system, etc.), and a local interconnect network component (LIN) 32. The vehicle 10 may use the CAN bus 26, MOST 28, FlexRay component 30, LIN 32, other suitable networks or communication systems, or a combination thereof, to communicate various information from sensors, such as within the vehicle or outside the vehicle, to various processors or controllers, such as within the vehicle or outside the vehicle. The vehicle 10 may include additional features or fewer features than those generally shown and / or disclosed herein.

[0085] In some embodiments, the vehicle 10 may include a steering system such as an EPS system, a steering system with steer-by-wire (e.g., it may include one or more controllers that control components of the steering system or communicate with it without using a mechanical connection between the steering wheel of the vehicle 10 and the wheel 22) or other suitable steering systems. The steering system may include an open-loop feedback control system or mechanism, a closed-loop feedback control system or mechanism, or a combination thereof. The steering system may be configured to receive various inputs, including but not limited to steering wheel position, input torque, one or more wheel positions, other suitable inputs or information, or a combination thereof. Additionally or alternatively, the input may include steering wheel torque, steering wheel angle, motor speed, vehicle speed, estimated motor torque command, other suitable inputs, or a combination thereof. The steering system may be configured to provide steering functionality and / or control to the vehicle 10. For example, the steering system may generate auxiliary torque based on various inputs. The steering system may be configured to selectively control the motor of the steering system using the auxiliary torque to provide steering assistance to the operator of the vehicle 10.

[0086] In some embodiments, the vehicle 10 may include a controller, such as Figure 21. The controller 100 is generally shown in FIG. 1. The controller 100 may include any suitable controller, such as an electronic control unit or other suitable controller. For example, the controller 100 may be configured to control various functions of the steering system and / or various functions of the vehicle 10. The controller 100 may include a processor 102 and a memory 104. The processor 102 may include any suitable processor, such as those described herein. Additionally or alternatively, the controller 100 may include any suitable number of processors in addition to or in addition to the processor 102. The memory 104 may include a single disk or multiple disks (e.g., a hard disk drive), and include a storage management module that manages one or more partitions within the memory 104. In some embodiments, the memory 104 may include flash memory, semiconductor (solid-state) memory, etc. The memory 104 may include a random access memory (RAM), a read-only memory (ROM), or a combination thereof. The memory 104 may include instructions that, when executed by the processor 102, cause the processor 102 to control at least various aspects of the vehicle 10.

[0087] The controller 100 may receive one or more signals from various measuring devices or sensors 106 that indicate sensed or measured characteristics of the vehicle 10. The sensors 106 may include any suitable sensors, measuring devices, and / or other suitable mechanisms. For example, the sensors 106 may include one or more torque sensors or devices, one or more steering wheel position sensors or devices, one or more motor position sensors or devices, one or more position sensors or devices, other suitable sensors or devices, or combinations thereof. The one or more signals may indicate steering wheel torque, steering wheel angle, motor speed, vehicle speed, other suitable information, or combinations thereof.

[0088] In some embodiments, the system 100 includes a steering wheel actuator 108. The steering wheel actuator 108 may include any suitable actuator and may include one or more actuators. The steering wheel actuator 108 may be configured to apply torque to a steering wheel of the vehicle 10. The steering wheel actuator 108 may include or communicate with one or more sensors (e.g., sensor 106) configured to sense the amount of torque applied to the steering wheel of the vehicle 10 by the operator and / or sense the amount of torque applied to the steering wheel actuator 108.

[0089] In some embodiments, as described, the controller 102 can be configured to provide thermal mitigation techniques for a motor. The motor can include any suitable motor of the vehicle 10 and / or any other suitable motor unrelated to the vehicle 10. The controller 102 can receive motor speed data from any suitable source including the sensor 106 or other suitable source. The controller 102 can determine whether the motor speed corresponding to the motor speed data is greater than a threshold speed. If the controller 102 determines that the motor speed is greater than the threshold speed, the controller 102 continues to monitor the motor speed via the motor speed data.

[0090] Alternatively, if the controller 102 determines that the motor speed is below a threshold speed, the controller 102 may calculate a thermal metric corresponding to a phase imbalance of the motor. In some embodiments, the threshold speed may include a calibratable threshold.

[0091] The controller 102 may identify at least one thermal mitigation parameter based on the thermal metric.The controller 102 may identify at least one thermal mitigation parameter using any suitable technique (eg, using at least one lookup table associated with the thermal metric or other suitable technique).

[0092] The controller 102 may generate at least one thermal management motor position command based on at least one thermal mitigation parameter. The controller 102 may selectively control the motor based on the thermal management motor position command. In some embodiments, the controller 102 may control the motor by modifying at least one phase voltage of the motor based on the thermal management motor position command.

[0093] In some embodiments, the controller 102 may use open loop control to generate a motor torque command based on the thermal management motor position command. The controller 102 may further selectively control the motor based on the motor torque command.

[0094] In some embodiments, the controller 102 may modify the thermal management motor position command by combining the thermal management motor position command with the measured steering wheel position. The controller 102 may use the modified thermal management motor position command to generate a motor torque command. The controller 102 may further selectively control the motor based on the motor torque command.

[0095] In some embodiments, the controller 102 can perform the methods described herein. However, the methods described herein as performed by the controller 102 are not meant to be limiting, and any type of software executed on a controller or processor can perform the methods described herein without departing from the scope of the present disclosure. For example, a controller (e.g., a processor executing software within a computing device) can perform the methods described herein.

[0096] Fig.12is a flow chart generally illustrating a thermal mitigation method 300 according to the principles of the present disclosure. At 302, the method 300 receives motor speed data. For example, the controller 102 may receive the motor speed data.

[0097] At 304, the method 300 determines whether the motor speed is less than a threshold. For example, the controller 102 may determine whether the motor speed is less than a threshold. If the controller 102 determines that the motor speed is not less than the threshold, the method 300 continues at 302. Alternatively, if the controller 102 determines that the motor speed is less than the threshold, the method 300 continues at 306.

[0098] At 306 , method 300 calculates a thermal metric corresponding to a phase imbalance of the motor. For example, controller 102 may calculate a thermal metric corresponding to a phase imbalance of the motor.

[0099] At 308 , the method 300 identifies at least one thermal mitigation parameter based on the thermal metric. For example, the controller 102 may identify at least one thermal mitigation parameter based on the thermal metric.

[0100] At 310 , the method 300 generates at least one thermal management motor position command based on at least one thermal mitigation parameter. For example, the controller 102 may generate at least one thermal management motor position command based on at least one thermal mitigation parameter.

[0101] At 312 , method 300 selectively controls the motor based on the thermal management motor position command. For example, controller 102 may selectively control the motor based on the thermal management motor position command.

[0102] In some embodiments, a method for preventing a motor from operating in a motor position with unbalanced phase current includes: receiving motor speed data, and in response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculating a thermal metric corresponding to a phase imbalance of the motor; identifying at least one thermal mitigation parameter based on the thermal metric; generating at least one thermal management motor position command based on the at least one thermal mitigation parameter; and selectively controlling the motor based on the thermal management motor position command.

[0103] In some embodiments, the method further comprises: using open loop control to generate a motor torque command based on a thermal management motor position command, and further selectively controlling the motor based on the motor torque command. In some embodiments, the method further comprises: modifying the thermal management motor position command by combining the thermal management motor position command with a measured steering wheel position; generating a motor torque command using the modified thermal management motor position command; and further selectively controlling the motor based on the motor torque command. In some embodiments, selectively controlling the motor based on the thermal management motor position command comprises: modifying at least one phase voltage of the motor based on the thermal management motor position command. In some embodiments, the threshold speed comprises a calibratable threshold. In some embodiments, identifying at least one thermal mitigation parameter based on a thermal metric comprises using at least one lookup table associated with the thermal metric. In some embodiments, the motor is associated with a steering system of a vehicle. In some embodiments, the steering system comprises a steer-by-wire steering system.

[0104] In some embodiments, a system for preventing a motor from operating at a motor position with unbalanced phase current includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive motor speed data, and in response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculate a thermal metric corresponding to a phase imbalance of the motor; identify at least one thermal mitigation parameter based on the thermal metric; generate at least one thermal management motor position command based on the at least one thermal mitigation parameter; and selectively control the motor according to the thermal management motor position command.

[0105] In some embodiments, the instructions further cause the processor to: use open loop control to generate a motor torque command based on a thermal management motor position command, and further selectively control the motor based on the motor torque command. In some embodiments, the instructions further cause the processor to: modify the thermal management motor position command by combining the thermal management motor position command with a measured steering wheel position; generate a motor torque command using the modified thermal management motor position command; and further selectively control the motor based on the motor torque command. In some embodiments, selectively controlling the motor based on the thermal management motor position command includes: modifying at least one phase voltage of the motor based on the thermal management motor position command. In some embodiments, the threshold speed includes a calibratable threshold. In some embodiments, identifying at least one thermal mitigation parameter based on a thermal metric includes using at least one lookup table associated with the thermal metric. In some embodiments, the motor is associated with a steering system of a vehicle. In some embodiments, the steering system includes a steer-by-wire steering system.

[0106] In some embodiments, a device for preventing a motor from operating in a motor position with unbalanced phase current includes a processor and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: receive motor speed data; and in response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculate a thermal metric corresponding to a phase imbalance of the motor; use at least one lookup table associated with the thermal metric to identify at least one thermal mitigation parameter based on the thermal metric; generate at least one thermal management motor position command based on the at least one thermal mitigation parameter; modify the thermal management motor position command by combining the thermal management motor position command with a measured steering wheel position; and selectively control the motor according to the modified thermal management motor position command.

[0107] In some embodiments, the motor is associated with a steering system of the vehicle. In some embodiments, the steering system comprises a steer-by-wire steering system.

[0108] The above discussion is intended to illustrate the principles and various embodiments of the present disclosure. Once the above disclosure is fully understood, many changes and modifications will become apparent to those skilled in the art. It is intended that the following claims be interpreted as including all such changes and modifications.

[0109] The word "example" is used herein to mean used as an example, instance or illustration. Any aspect or design described herein as an "example" is not necessarily to be interpreted as being more preferred or advantageous than other aspects or designs. On the contrary, the use of the word "example" is intended to present the concept in a specific way. As used in this application, the term "or" is intended to represent an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clearly seen from the context, "X includes A or B" is intended to represent any natural inclusive arrangement. That is, if X includes A; X includes B; or X includes both A and B, then "X includes A or B" is satisfied in any of the foregoing cases. In addition, the article "a / an" used in this application and the appended claims should generally be interpreted as meaning "one or more", unless otherwise specified or clearly pointed to the singular form from the context. In addition, unless so described, the use of the term "embodiment" or "one embodiment" throughout the text is not intended to represent the same embodiment or embodiment.

[0110] Implementations of the systems, algorithms, methods, instructions, etc. described herein may be implemented in hardware, software, or any combination thereof. Hardware may include, for example, a computer, an intellectual property (IP) core, an application specific integrated circuit (ASIC), a programmable logic array, an optical processor, a programmable logic controller, microcode, a microcontroller, a server, a microprocessor, a digital signal processor, or any other suitable circuit. In the claims, the term "processor" shall be understood to include any of the foregoing hardware, either alone or in combination. The terms "signal" and "data" may be used interchangeably.

[0111] As used herein, the term module may include a packaged functional hardware unit designed for use with other components, a set of instructions executable by a controller (e.g., a processor executing software or firmware), a processing circuit configured to perform a specific function, and a self-contained hardware or software component that interfaces with a larger system. For example, a module may include an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), an electrical circuit, a digital logic circuit, an analog circuit, a combination of discrete circuits, gate circuits, and other types of hardware, or a combination thereof. In other embodiments, a module may include a memory that stores instructions executable by a controller to implement the functions of the module.

[0112] Furthermore, in one aspect, for example, the systems described herein may be implemented using a general purpose computer or general purpose processor with a computer program that, when executed, performs any corresponding method, algorithm, and / or instruction described herein. Additionally or alternatively, for example, a special purpose computer / processor may be utilized that may include other hardware for performing any method, algorithm, or instruction described herein.

[0113] In addition, all or part of the implementation of the present disclosure may take the form of a computer program product accessible from, for example, a computer usable or computer readable medium. A computer usable or computer readable medium may be, for example, any device that can tangibly contain, store, communicate, or transport a program for use by or in conjunction with any processor. The medium may be, for example, an electronic, magnetic, optical, electromagnetic device, or a semiconductor device. Other suitable media may also be used.

[0114] The above embodiments, implementations and aspects have been described to allow easy understanding of the present disclosure and are not intended to limit the present disclosure. On the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope should be given the broadest interpretation to cover all such modifications and equivalent structures permitted by law.

Claims

1. A method for preventing a motor from operating in a motor position with unbalanced phase currents, the method comprising: Receive motor speed data; as well as In response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculating a thermal quantity corresponding to a phase imbalance of the motor; identifying at least one thermal mitigation parameter based on the thermal metric; generating at least one thermal management motor position command based on the at least one thermal mitigation parameter; as well as The motor is selectively controlled based on the thermal management motor position command.

2. The method according to claim 1, further comprising: Open loop control is used to generate a motor torque command based on the thermal management motor position command, and the motor is further selectively controlled based on the motor torque command.

3. The method according to claim 1, further comprising: The thermal management motor position command is modified by combining the thermal management motor position command with a measured steering wheel position.

4. The method according to claim 3, further comprising: generating a motor torque command using the modified thermal management motor position command; as well as The motor is further selectively controlled based on the motor torque command.

5. The method according to claim 1, wherein: Selectively controlling the motor based on the thermal-management motor position command includes modifying at least one phase voltage of the motor based on the thermal-management motor position command.

6. The method according to claim 1, wherein: The threshold speed comprises a calibratable threshold.

7. The method according to claim 1, wherein: Identifying the at least one thermal mitigation parameter based on the thermal metric includes using at least one lookup table associated with the thermal metric.

8. The method according to claim 1, wherein: The motor is associated with a steering system of the vehicle.

9. The method according to claim 8, wherein: The steering system comprises a steer-by-wire steering system.

10. A system for preventing a motor from operating in a motor position with unbalanced phase currents, the system comprising: processor; as well as a memory comprising instructions which, when executed by the processor, cause the processor to: Receive motor speed data, and In response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculating a thermal quantity corresponding to a phase imbalance of the motor; identifying at least one thermal mitigation parameter based on the thermal metric; generating at least one thermal management motor position command based on the at least one thermal mitigation parameter; as well as The motor is selectively controlled based on the thermal management motor position command.

11. The system according to claim 10, wherein: The instructions further cause the processor to use open loop control to generate a motor torque command based on the thermal management motor position command, and to selectively control the motor further based on the motor torque command.

12. The system according to claim 10, wherein: The instructions further cause the processor to: modifying the thermal management motor position command by combining the thermal management motor position command with a measured steering wheel position; generating a motor torque command using the modified thermal management motor position command; as well as The motor is further selectively controlled based on the motor torque command.

13. The system according to claim 10, wherein: Selectively controlling the motor based on the thermal-management motor position command includes modifying at least one phase voltage of the motor based on the thermal-management motor position command.

14. The system according to claim 10, wherein: The threshold speed comprises a calibratable threshold.

15. The system according to claim 10, wherein: Identifying the at least one thermal mitigation parameter based on the thermal metric includes using at least one lookup table associated with the thermal metric.

16. The system of claim 10, wherein: The motor is associated with a steering system of the vehicle.

17. The system of claim 16, wherein: The steering system comprises a steer-by-wire steering system.

18. An apparatus for preventing a motor from operating in a motor position with unbalanced phase currents, the apparatus comprising: processor; as well as a memory comprising instructions which, when executed by the processor, cause the processor to: Receive motor speed data; as well as In response to determining that the motor speed data indicates that the speed of the motor is below a threshold speed: calculating a thermal quantity corresponding to a phase imbalance of the motor; identifying at least one thermal mitigation parameter based on the thermal metric using at least one lookup table associated with the thermal metric; generating at least one thermal management motor position command based on the at least one thermal mitigation parameter; modifying the thermal management motor position command by combining the thermal management motor position command with a measured steering wheel position; as well as The motor is selectively controlled based on the modified thermal management motor position command.

19. The apparatus according to claim 18, wherein: The motor is associated with a steering system of the vehicle.

20. The apparatus of claim 19, wherein: The steering system comprises a steer-by-wire steering system.

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