System and method for speed torque control of brush DC motor

Abstract

Technical solutions for controlling a brushed direct current (DC) motor are described, including: determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining a torque command signal based on the speed difference signal; determining a voltage command based on the torque command signal; and applying a DC voltage to the brushed DC motor based on the voltage command. Determining the torque command signal based on the speed difference signal further includes at least one of: determining a modified proportional torque component, the modified proportional torque component including a product of a feed-forward gain term and the speed command signal, where the torque command signal includes the modified proportional torque component; and / or determining a modified derivative torque component that includes a time derivative of a motor speed of the brushed DC motor, where the torque command signal includes the modified derivative torque component.

Description

Technical Field

[0001] The present disclosure relates to methods and systems for operating a brushed DC motor. Background Art

[0002] Brushed DC motors are used in a variety of applications. One such application is in power steering systems for vehicles. Significant advantages of brushed DC motors include low-cost components, less circuitry, simplicity, and ease of control when compared to alternatives such as AC motors.

[0003] For smooth operation and a better customer experience, active speed control can be used to control the brushed DC motor of the column position module (CPM) using a speed-torque controller. Summary of the Invention

[0004] According to one or more embodiments, a method for controlling a brushed DC motor includes determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining a torque command signal based on the speed difference signal; determining a voltage command based on the torque command signal; and applying a DC voltage to the brushed DC motor based on the voltage command. The torque command signal includes at least one of a modified proportional torque component and / or a modified derivative torque component. Determining the torque command signal includes at least one of: determining a modified proportional torque component comprising a product of a feedforward gain term and the speed command signal; and / or determining a modified derivative torque component comprising a time derivative of the motor speed of the brushed DC motor.

[0005] According to one or more embodiments, a motor control system is provided. The motor system includes: a brushed DC motor having a set of brushes; a voltage regulator configured to apply a DC voltage to the brushed DC motor based on a voltage command; and a controller configured to: determine a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determine a torque command signal based on the speed difference signal; and determine a voltage command based on the torque command signal. The torque command signal includes at least one of a modified proportional torque component and / or a modified derivative torque component. Determining the torque command signal includes at least one of: determining a modified proportional torque component including a product of a feedforward gain term and the speed command signal; and / or determining a modified derivative torque component including a time derivative of the motor speed of the brushed DC motor.

[0006] According to one or more embodiments, a method for operating a brushed direct current (DC) motor to adjust a column position of a steering system in a vehicle is provided. The method includes determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining a torque command signal based on the speed difference signal; determining a voltage command based on the torque command signal; and applying a DC voltage to the brushed DC motor based on the voltage command. The torque command signal includes at least one of a modified proportional torque component, a modified derivative torque component, and / or a position-dependent torque component. Determining the torque command signal includes at least one of: determining a modified proportional torque component including a product of a feedforward gain term and the speed command signal; determining a modified derivative torque component including a time derivative of the motor speed of the brushed DC motor; and / or determining a position-dependent torque component based on at least one of a position and an orientation of the brushed DC motor.

[0007] These and other advantages and features will become more apparent from the following description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0009] Figure 1 A column position module (CPM) of a steering system in a vehicle according to aspects of the present disclosure is shown;

[0010] Figure 2 1. A schematic block diagram of a system for controlling a brushed DC motor according to aspects of the present disclosure is shown;

[0011] Figure 3A A graph showing relative pitch over time of a CPM module moving in a column downward direction according to aspects of the present disclosure;

[0012] Figure 3B a graph showing a Fast Fourier Transform (FFT) analysis of pitch versus frequency for a CPM module moving in a column downward direction;

[0013] Figure 4 shows a schematic block diagram of a motor controller for operating a DC motor according to aspects of the present disclosure;

[0014] Figure 5 a graph showing motor speed versus time using each of conventional control techniques and the control technique of the present disclosure, both in voltage mode, according to aspects of the present disclosure;

[0015] Figure 6 a graph showing motor speed versus time using each of conventional control techniques and the control technique of the present disclosure, both in current control mode, in accordance with aspects of the present disclosure; and

[0016] 7A to 7B A flow chart listing steps in a method for operating a DC motor according to aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0017] Reference will now be made to the accompanying drawings, wherein the present disclosure will be described with reference to specific embodiments, rather than limiting the present disclosure, it being understood that the disclosed embodiments are merely illustrative of non-limiting embodiments of the present disclosure that may be embodied in various forms and alternatives. The drawings are not necessarily drawn to scale, and some features may be exaggerated or minimized to illustrate details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to employ the present disclosure in various ways.

[0018] As used herein, the terms module and submodule refer to one or more processing circuits (e.g., application-specific integrated circuits (ASICs), electronic circuits), processors (shared, dedicated, or grouped) and memories that execute one or more software or firmware programs, combinatorial logic circuits, and / or other suitable components that provide the described functionality. It will be understood that the submodules described below can be combined and / or further divided.

[0019] Generally speaking, friction and load torque are not considered when designing speed-torque controllers for operating brushed DC motors. However, for certain applications where the load and friction torque are high and significantly depend on the position of the driven component, the controller can advantageously combine these torques to provide the desired smooth performance. Operation of a column position module (CPM) is one such application where the load and friction torque are relatively high and significantly depend on the position of the column module driven by a brushed DC motor. Therefore, combining these load and friction torques can provide advantageous results for operating the brushed DC motor in a CPM.

[0020] Referring now to the accompanying drawings, the technical solutions will be described with reference to specific embodiments, but not limited thereto. Figure 1 An exemplary embodiment of a column position module (CPM) 20 of a steering system in a vehicle is shown, which may utilize the disclosed systems and methods to control a DC motor.

[0021] The CPM 20 includes a steering shaft 22 configured to be attached to a steering wheel, which may also be referred to as a steering wheel, that a person may use to steer a vehicle. The CPM 20 includes a steering actuator 24 attached to the steering shaft. The steering actuator 24 may supplement the force applied by the person to provide a power-assisted steering function. The CPM 20 also includes a telescopic actuator motor 26 configured to control the axial position of the steering wheel by moving the steering shaft 22 in an axial direction. The CPM 20 also includes a rake actuator motor 28 configured to control the vertical position of the steering wheel by moving the end of the steering shaft in a radial direction.

[0022] Any or all of the steering actuator 24, telescopic actuator motor 26, and / or tilt actuator motor 28 may include brushed DC motors and may be controlled using the systems and methods of the present disclosure. However, the systems and methods of the present disclosure may be used with brushed DC motors in other vehicle applications, such as for window or lock actuators. The systems and methods of the present disclosure are not limited to use in vehicles, but may be used with brushed DC motors in a variety of different applications.

[0023] Figure 2 1 is a schematic block diagram of a system 50 for controlling brushed DC motors 26, 28. Figure 2 As shown, the brushed DC motors 26, 28 include a set of brushes 30, 32 for transmitting DC current from a fixed terminal to a rotor winding. The set of brushes 30, 32 includes a first brush 30 configured to be connected to a power source to receive DC current. The set of brushes 30, 32 also includes a second brush 32 configured to be connected to a current sink (such as a ground terminal).

[0024] System 50 includes a controller 60. Controller 60 may include any suitable controller, such as an electronic control unit or other suitable controller. Controller 60 may be configured to control various functions of, for example, a steering system and / or various functions of a vehicle. Controller 60 may include a processor 62 and a memory 64. Processor 62 may include any suitable processor, such as the processors described herein. Additionally or alternatively, controller 60 may include any suitable number of processors in addition to or in addition to processor 62. Memory 64 may include a single disk or multiple disks (e.g., a hard drive) and a storage management module that manages one or more partitions within memory 64. In some embodiments, memory 64 may include flash memory, semiconductor (solid-state) memory, or the like. Memory 64 may include random access memory (RAM), read-only memory (ROM), or a combination thereof. Memory 64 may include instructions that, when executed by processor 62, cause processor 62 to control at least various aspects of the vehicle. Additionally or alternatively, memory 64 may include instructions that, when executed by processor 62, cause processor 62 to perform functions associated with the systems and methods described herein.

[0025] The controller 60 may be operatively connected to the voltage regulator 52. The voltage regulator 52 may be configured to apply a DC voltage v to the first brush 30 of the brushed DC motor 26, 28. The voltage regulator 52 may be configured to apply a DC voltage v to the first brush 30 of the brushed DC motor 26, 28 based on a voltage command v from the controller 60. cmd To generate a DC voltage v.

[0026] In some embodiments, as Figure 2 As shown, the system 50 may include a current sensor 54 configured to measure the DC current supplied to the brushed DC motors 26, 28 and to generate a motor current signal i m The motor current signal is transmitted to the controller 60 and represents the actual motor current in the windings of the brushed DC motors 26, 28. Additionally or alternatively, as in Figure 2 As shown, the system 50 may include a position sensor 56 configured to measure the rotational position of the brushed DC motors 26, 28 and convert the motor position signal ω into a value corresponding to the position of the brushed DC motors 26, 28. m Transmitted to the controller 60.

[0027] In some embodiments, the controller 60 can perform the methods described herein. However, the methods described herein as being performed by the controller 60 is not intended 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 (such as a processor executing software within a computing device) can perform the methods described herein.

[0028] Figure 3A A graph over time is shown of the relative pitch of the tilt actuator motor 28 moving the CPM 20 in a column-down direction. Figure 3B A graph showing a Fast Fourier Transform (FFT) analysis of pitch versus frequency for a CPM module moving in a column downward direction. Figure 3B A large spike at approximately 4 Hz is shown. This spike represents undesirable noise or vibration that a person using the CPM may perceive. Similar undesirable noise or vibration may be generated by the tilt actuator motor 28 moving in either direction or the telescopic actuator motor 26 moving in either direction. The method and system of the present disclosure are intended to minimize or eliminate such vibrations that would otherwise cause undesirable noise and vibration. Furthermore, the techniques of the present disclosure can be applied to reduce noise or vibration in any brushed DC motor application.

[0029] Figure 4 A schematic block diagram of a motor controller 70 for operating a DC motor according to aspects of the present disclosure is shown. The motor controller 70 is configured as a speed controller following a speed-torque-voltage path. However, the principles of the present disclosure may be applied to other controller configurations.

[0030] The motor controller 70 includes a subtractor 72 configured to reduce the speed command signal ω to ref Subtract motor speed ω m , and calculate the speed command signal ω ref and motor speed ω m The speed difference signal ω diff The motor controller 70 further includes a torque command generator 74 configured to generate a torque command based on the speed difference signal ω diff To generate the torque command signal τ cmd The torque command generator 74 may use a proportional-integral (PI) control loop to generate the torque command signal τ cmd However, other control techniques may be used, such as a proportional-integral-derivative (PID) control loop or a lookup table.

[0031] The motor controller 70 further includes a torque limiter 76 (also referred to as an anti-windup limiter) configured to limit the torque of the motor based on the torque command signal τ cmd To generate the limited torque command τ cmdlim The torque limiter 76 may be configured to be based on one or more operating constraints (such as a supply current limit I slim , motor current limit I MAX and / or the maximum available voltage V MAX ) to limit the torque command signal τ cmd .

[0032] The motor controller 70 further includes a command current generator 78 configured to generate a current based on the limited torque command τ cmdlim To generate the current command i cmd In some embodiments, the command current generator 78 generates the limited torque command τ by cmdlim Divide by the back electromotive force constant K to generate the current command i cmd .

[0033] The motor controller 70 further includes a current regulator 80 configured to generate a current based on the current command i cmd To generate the voltage command v cmd In some embodiments, as Figure 4 As shown, the current regulator 80 converts the motor current signal i m The current regulator 80 may use a control loop (such as a PI control loop) to control the current based on the current command i cmd and the motor current signal i m The voltage command v is calculated by the difference between cmd Additionally or alternatively, the current regulator 80 may use a reference model (such as an equation or a lookup table) to calculate the current based on the current command i cmd and the motor current signal i m To determine the voltage command v cmd .

[0034] The following equations (1) and (2) show a mathematical model of a DC motor.

[0035]

[0036] Here, v is the voltage applied to the DC motor, i is the motor current, R is the resistance, L is the inductance, K is the back electromotive force constant, J is the inertia of the motor, B is the viscosity constant, ω is the motor speed, and τ e is the generated electrical torque, and τ LF Add friction torque to the load. v b represents the voltage drop due to the brushes 30 , 32 .

[0037] The following equation (3) describes the brush voltage drop v due to brushes 30, 32: b V0 is the brush voltage parameter of the motor, and I0 is the current parameter of the motor.

[0038] Brush voltage drop v b occurs in the direction of the motor current i, as described in equation (3).

[0039]

[0040] Where sign(i) represents the polarity of the current, and sign(i) is -1 for negative motor current (ie, where i<0), 0 for zero motor current (ie, i=0), or +1 for positive motor current (where i>0).

[0041] Generated electrical torque τ e is directly related to the motor current, as explained in equation (4). LF are the load and friction torque, and can be expressed by (5).

[0042] τ e =Ki (4)

[0043] τ LF (θ)=τ L (θ)+C*sign(ω) (5)Here, θ is the motor position, C is the Coulomb constant, and τ L Indicates the load torque. For CPM applications, the load torque τ L Depends heavily on column position. Note that when the motor is connected to a larger system (ie the steering system), the load torque, load and friction torque increase with the resulting inertia.

[0044] The following equation (6) provides the PI control loop according to the actual speed ω m and reference speed ω ref Calculate the torque command τ cmd The general method.

[0045] τ cmd =K p (ω ref -ω m )+K i ∫(ω ref -ω m )dt (6) where K p represents the proportional gain value, and K i Indicates the integral gain value. Proportional gain value K p and / or integral gain value K i Either or both of can be constants.

[0046] A load-friction torque profile based on the motor position θ can be added as a feed-forward term in equation (7). A first technique of the present disclosure for calculating the torque command is shown in equation (7).

[0047] τ cmd =K p (ω ref -ω m )+K i ∫(ω ref-ω m )dt+τ LF (θ) (7)

[0048] Equation (7) can be expressed as a closed-loop transfer function as shown in Equation (8).

[0049]

[0050] To obtain a first-order response, a pole is placed at the zero position as shown in equation (9).

[0051]

[0052] Here, -α is the desired pole location for the first-order equation. α is also referred to as the bandwidth of the system. The bandwidth α corresponds to the inverse of the time constant (in seconds) for the step response to reach 1-1 / e≈63.2% of its final (asymptotic) value (e.g., in the case of a step increase). The bandwidth α can be determined based on the requirements of the specific application of the brushed DC motor. It is assumed that the pole that is canceled by the zero of the same value is located at -α1. The following set of equations (10) can be derived from equation (8).

[0053]

[0054] Solving these equations yields the proportional gain K p and integral gain K i , as explained in equation group (11).

[0055] K p =aJ and K i =aB(11)

[0056] A disadvantage of the first two controllers is that the zeros and poles are is canceled out at a certain speed, and this value depends on the system parameters and there is no way to control it. At a certain speed, the system may show undesirable performance. In addition, some other constraints on the gain may appear during operation. For example, in order to stabilize the operation, the integral gain K i is restricted to a single number. This allows the pole positions to be set at specific locations, as shown in equation group (11).

[0057] Equation (7) can be expressed as the feedforward gain term K f The modification is made as shown below in equation (12). This provides an additional degree of freedom to keep one of these gains within certain limits and set the poles and zeros at the same time.

[0058] τ cmd =K p (K f ω ref -ωm )+K i ∫(ω ref -ω m )dt+τ LF (θ) (12)

[0059] For small and smooth systems, friction and load torque can be neglected. The closed-loop transfer function can be expressed as shown in equation (13):

[0060]

[0061] The three controller gains K are set as explained in equation group (14) f , K p and K i Equation (13) is simplified to a first-order system as illustrated in Equation (15). In this case, the two poles and the zero are placed at the same location.

[0062]

[0063] It can be found that for the integral gain K i =K ilim , the system becomes unstable when it exceeds a certain value. If the conventional controller of equation (6) is used with the gain values ​​as shown in the equation group (11), there may be no lim =K ilim However, using a feedforward gain term K f The controller of equation (12) is set as described below by placing one pole and zero at -α1 and the other pole or closed-loop pole at -α. The following equation group (16) shows the setting of gains to limit the integral gain K i And at the same time select the governing equations for the desired pole locations.

[0064]

[0065] Solving these equations yields the values ​​explained in equation group (17). Here, K i =K ilim And set α to the desired position.

[0066]

[0067] From the torque command calculated by the controller using equation (7) or equation (12), the current command is calculated as explained in equation (18).

[0068]

[0069] The voltage command is measured using the system model for voltage mode operation. In equation (19), the actual motor current i is used for the dynamic term To avoid the command torque τ cmd and command current i cmd The sudden change causes a huge increase in voltage.

[0070]

[0071] For current mode operation, the existing architecture of the brushed DC motor for the EPS system is used, as explained in equation (20). The gains of the PI current regulator are set as shown in the set of equations (21).

[0072] v cmd =K pc (i cmd -i)+ K ic ∫(i cmd -i)dt (20)

[0073] K pc =ω d L; and K ic =ω d R (21)

[0074] The controller performance is observed and compared with the conventional approach of position-dependent load torque. The desired pole position -a can have a value of -20, and the current regulator pole ω d Can have a value of -200π. Current regulator pole ω d can be set to a higher value than the command current generator because the inner loop gain may need to be set at least 10 times higher than the outer loop to avoid undesired disturbances.A position-dependent load curve having a constant term and a sinusoidal term is applied to the motor.

[0075] Figures 5 and 6 The performance comparison between the proposed method of Equation (7) with the load friction torque adjustment term and the gain of the equation group (11) and the conventional method of Equation (6) with the gain of the equation group (11) in voltage mode and current mode, respectively, is shown.

[0076] Figure 5 A graph of motor speed versus time is shown and includes a first graph 100 showing a speed reference having a step function that jumps from 0 rad / s to 2000 rad / s at time t=0.25s and then jumps from 2000 rad / s back to 0 rad / s at time t=1.75s. Figure 5The graph also includes a second graph 102 showing the motor speed for voltage control using the conventional control technique of equation (6) with the gains of the set of equations (11). Figure 5 The graph also includes a third graph 104 showing the motor speed for voltage control using the disclosed control technique (as explained in equation (7)) with the gain of equation group (11). As shown, the disclosed control technique shown on third graph 104 is generally closer to the speed reference of first graph 100 and does not exhibit the oscillations present in the conventional control technique shown on second graph 102.

[0077] Figure 6 A graph of motor speed versus time is shown and includes a fourth graph 110 showing a speed reference having a step function that jumps from 0 rad / s to 2000 rad / s at time t=0.25s and then jumps from 2000 rad / s back to 0 rad / s at time t=1.75s. Figure 6 The graph also includes a fifth graph 112 showing motor speed for current control using the conventional control technique of equation (6) with the gain of the set of equations (11). Figure 6 The graph also includes a sixth graph 114 showing motor speed for current control using the disclosed control technique (as explained in equation (7)) with the gains of equation group (11). As shown, the disclosed control technique shown in sixth graph 114 is generally closer to the speed reference of fourth graph 110 and does not exhibit the oscillations present in the conventional control technique shown in fifth graph 112.

[0078] The controller with the conventional PI controller and load torque regulation first proposed provides significantly better speed response in steady state in both voltage mode and current mode. The time constant from the step response matches the time constant of 0.05s set by the pole -α (located at -20) of the speed-torque PI controller. The additional value of around 0.0026s is caused by the sampling delay of the different components running at 500Hz and 16kHz sampling rates and the time constant of the current regulator for current mode operation. The proposed modified PI controller as explained in equation (12) and with the gain of the set of equations (14) also provides similar performance and results for loads with varying position.

[0079] Another possible way to reduce speed pulsation without any adjustment is to introduce a derivative term to the PI controller of equation (6). The following equation (22) shows the proposed modified proportional, integral, derivative (PID) controller. The proposed modified PID controller differs from the conventional PID controller in that the derivative term Based only on motor speed ω m The time derivative of , rather than being based on a differential term such as (ω as in a conventional PID controller ref -ω m ).

[0080]

[0081] The modified PID controller of equation (22) can be expressed as a closed-loop transfer function as shown in equation (23).

[0082]

[0083] By setting the gains as shown in equation group (24), the transfer function can be simplified to a first-order system with a pole at -α.

[0084]

[0085] The closed-loop transfer function becomes as shown in equation (25):

[0086]

[0087] Equation (22) can be adjusted to accommodate load changes, as shown in Equation (26):

[0088]

[0089] For all methods disclosed herein, increasing the pole position reduces velocity ripple. However, due to some delay in filtering and processing, it may be advantageous to set the pole position at least 20 times lower than the sampling frequency. For example, the pole position can be further calibrated through experimentation. Under no-load or constant-load conditions, all control techniques disclosed herein function normally without adjustment. In applications where the load varies significantly with position, an adjustment term may be beneficial.

[0090] In the event of a current measurement failure, the current regulator may not use current control mode. In the event of a current measurement failure, the voltage mode equations may be modified as shown in equation (27). All speed-torque controllers are capable of compensating for the missing terms due to the absence of current data in voltage mode. Alternatively, the voltage command may be determined as illustrated in equation (28).

[0091] v cmd=Ri cmd +Kω m (27)

[0092]

[0093] 7A to 7B A flow chart listing the steps in a method 200 for operating a DC motor according to aspects of the present disclosure is shown. The method 200 may be performed by the motor controller 70 of the present disclosure. It will be understood from the present disclosure that the order of operations within the method is not limited to the following. 7A to 7B Rather, the steps are not necessarily performed in the order illustrated in the accompanying drawings, but may be performed in one or more altered orders where applicable and in accordance with the present disclosure.

[0094] At 202, method 200 determines a speed difference signal based on the difference between the speed command signal and the motor speed of the brushed DC motor. For example, processor 62 may execute instructions to implement subtractor 72 to calculate a speed difference signal representing the speed command signal ω. ref and motor speed ω m The speed difference signal ω diff .

[0095] At 204, the method 200 determines a torque command signal based on the speed difference signal. For example, the processor 62 may execute instructions to implement the torque command generator 74 to generate a torque command signal based on the speed difference signal ω. diff To generate the torque command signal τ cmd Torque command signal τ cmd One or more of a modified proportional torque component and / or a modified derivative torque component may be included.

[0096] Step 204 may include determining a modified proportional torque component at 204A, the modified proportional torque component comprising a product of a feed-forward gain term and a speed command signal. For example, the torque command signal τ cmd A modified proportional torque component K may be included p (K f ω ref -ω m ), as described in equation (12).

[0097] In some embodiments, the method 200 further includes determining a feed-forward gain term to enable the brushed DC motor to meet a given bandwidth. For example, the feed-forward gain term can be determined as illustrated in equation group (14).

[0098] Step 204 may include determining, at 204B, a modified derivative torque component comprising a time derivative of the motor speed of the brushed DC motor. For example, the torque command signal τ cmdA modified derivative torque component may be included As described in equation (22).

[0099] Step 204 may also include determining, at 204C, a position-dependent torque component of the torque command signal based on the position of the brushed DC motor and / or the direction of the brushed DC motor. For example, the processor 62 may execute instructions to calculate or otherwise determine the position-dependent torque component τ based on the motor position θ. LF (θ), and the torque command signal τ cmd A position-dependent torque component τ may be included LF (θ), as described in Equation (26). The direction may include the brushed DC motor operating in a forward direction or in a reverse direction opposite to the forward direction, and the position-dependent torque component may be different for the brushed DC motor operating in the forward direction, the reverse direction, or at rest.

[0100] In some embodiments, the position-dependent torque component is also based on the direction in which the brushed DC motor is operating. For example, the position-dependent torque component may be different depending on whether the brushed DC motor is operating in a forward direction or a reverse direction. Such a forward direction or a reverse direction may correspond to the telescopic actuator motor 26 moving the CPM 20 in a corresponding inward or outward direction, or the tilt actuator motor 28 moving the CPM 20 in a corresponding column-up or column-down direction.

[0101] In some embodiments, a lookup table may be used to determine the position-dependent torque component based on the position of the brushed DC motor.

[0102] At 206, method 200 determines a limited torque command signal based on the torque command signal to satisfy at least one of: a supply current limit value, a motor current limit value, and a maximum available voltage value. For example, processor 62 may execute instructions to implement torque limiter 76 to determine a limited torque command signal based on the torque command signal τ. cmd To determine the limited torque command τ cmdlim .

[0103] Step 206 may include: determining a capacity limit value different from the supply current limit value based on a nonlinear function of the supply current limit value at 206A; and determining a limited torque command signal based on the capacity limit value at 206B. For example, the torque limiter 76 may be configured to determine the limited torque command signal τ based on the capacity limit. cmdlim , the capability limit can be determined as described in U.S. Patent No. 10,530,282 to Pramod et al. and assigned to Steering Solutions IP Holding Corporation.

[0104] Step 206 may include calculating a limited torque command signal based on a nonlinear function of the supply current limit value at 206C. For example, the torque limiter 76 may be configured to determine the limited torque command τ based on a nonlinear function of the supply current limit value. cmdlim , the supply current limit value can be determined as described in U.S. Patent No. 11,290,042 issued to Pramod et al. and assigned to Steering Solutions Intellectual Property Holdings, Inc.

[0105] At 208, method 200 determines a voltage command based on the torque command signal. For example, processor 62 may execute instructions to implement command current generator 78 and current regulator 80, wherein command current generator 78 is based on the limited torque command τ cmdlim To generate the current command i cmd , and wherein the current regulator 80 is based on the current command i cmd To generate the voltage command v cmd .

[0106] At 210 , the method 200 applies a DC voltage to the brushed DC motor based on the voltage command. For example, the voltage regulator 52 may generate a DC voltage v and apply it to the first brush 30 of the brushed DC motor 26 , 28 , where the DC voltage v is based on the voltage command v from the controller 60 . cmd .

[0107] The present disclosure provides a method for controlling a brushed DC motor. The method includes determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining a torque command signal based on the speed difference signal; determining a voltage command based on the torque command signal; and applying a DC voltage to the brushed DC motor based on the voltage command. Determining the torque command signal based on the speed difference signal also includes at least one of: determining a modified proportional torque component, the modified proportional torque component comprising a product of a feedforward gain term and the speed command signal, wherein the torque command signal comprises the modified proportional torque component; and determining a modified derivative torque component comprising a time derivative of the motor speed of the brushed DC motor, wherein the torque command signal comprises the modified derivative torque component.

[0108] In some embodiments, determining the torque command signal based on the speed difference signal includes determining a modified proportional torque component comprising a product of a feedforward gain term and the speed command signal, and wherein the torque command signal includes the modified proportional torque component.

[0109] In some embodiments, the method further includes determining a feed-forward gain term to enable the brushed DC motor to meet a given bandwidth.

[0110] In some embodiments, the feedforward gain term is determined according to the following equation: where K f is the feedforward gain term, K i is the integral gain term, K p is the proportional gain term, and a is the given bandwidth.

[0111] In some embodiments, determining the torque command signal based on the speed difference signal includes determining a modified derivative torque component comprising a time derivative of a motor speed of the brushed DC motor, and wherein the torque command signal includes the modified derivative torque component.

[0112] In some embodiments, the method further comprises determining a position-dependent torque component based on the position of the brushed DC motor.In some embodiments, the torque command signal comprises a position-dependent torque component.

[0113] In some embodiments, the position-dependent torque component is also based on the operating direction of the brushed DC motor.

[0114] In some embodiments, determining the position-dependent torque component includes using a lookup table to determine the position-dependent torque component based on the position of the brushed DC motor.

[0115] In some embodiments, the method further comprises determining a limited torque command signal based on the torque command signal to satisfy at least one of: a supply current limit value, a motor current limit value, and a maximum available voltage value. In some embodiments, determining a voltage command further comprises determining a voltage command based on the limited torque command signal.

[0116] In some embodiments, determining the limited torque command signal based on the torque command signal further includes at least one of: determining a capacity limit value different from the supply current limit value based on a nonlinear function of the supply current limit value, and determining the limited torque command signal based on the capacity limit value; and / or calculating the limited torque command signal based on the nonlinear function of the supply current limit value.

[0117] The present disclosure provides a motor control system. The motor control system includes: a brushed DC motor having a set of brushes; a voltage regulator configured to apply a DC voltage to the brushed DC motor based on a voltage command; and a controller. The controller is configured to: determine a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determine a torque command signal based on the speed difference signal; and determine a voltage command based on the torque command signal. Determining the torque command signal based on the speed difference signal includes at least one of: determining a modified proportional torque component, the modified proportional torque component including a product of a feedforward gain term and a speed command signal, and wherein the torque command signal includes the modified proportional torque component; and determining a modified derivative torque component, the modified derivative torque component including a time derivative of the motor speed of the brushed DC motor, and wherein the torque command signal includes the modified derivative torque component.

[0118] In some embodiments, determining the torque command signal based on the speed difference signal further comprises determining a modified proportional torque component comprising a product of a feedforward gain term and the speed command signal, and wherein the torque command signal comprises the modified proportional torque component.

[0119] In some embodiments, the controller is further configured to determine a feed-forward gain term to enable the brushed DC motor to meet a given bandwidth.

[0120] In some embodiments, the controller is further configured to determine a feedforward gain term according to the following equation: where K f is the feedforward gain term, K i is the integral gain term, K p is the proportional gain term, and a is the given bandwidth.

[0121] In some embodiments, determining the torque command signal based on the speed difference signal includes determining a modified derivative torque component comprising a time derivative of a motor speed of the brushed DC motor, and wherein the torque command signal includes the modified derivative torque component.

[0122] In some embodiments, the controller is further configured to determine a position-dependent torque component based on a position of the brushed DC motor, and the torque command signal includes the position-dependent torque component.

[0123] In some embodiments, the position-dependent torque component is also based on the operating direction of the brushed DC motor.

[0124] In some embodiments, determining the position-dependent torque component includes using a lookup table to determine the position-dependent torque component based on the position of the brushed DC motor.

[0125] In some embodiments, the controller is further configured to determine a limited torque command signal based on the torque command signal to satisfy at least one of: a supply current limit value, a motor current limit value, and a maximum available voltage value, and determining the voltage command further comprises determining the voltage command based on the limited torque command signal.

[0126] The present disclosure also provides a method for operating a brushed DC motor to adjust a column position of a steering system in a vehicle. The method includes: determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining a torque command signal based on the speed difference signal; determining a voltage command based on the torque command signal; and applying a DC voltage to the brushed DC motor based on the voltage command. In some embodiments, determining the torque command signal based on the speed difference signal further includes at least one of: determining a modified proportional torque component, the modified proportional torque component comprising a product of a feedforward gain term and the speed command signal, wherein the torque command signal comprises the modified proportional torque component; determining a modified derivative torque component, the modified derivative torque component comprising a time derivative of the motor speed of the brushed DC motor, wherein the torque command signal comprises the modified derivative torque component; and determining a position-dependent torque component based on a position of the brushed DC motor, wherein the torque command signal comprises the position-dependent torque component.

[0127] Although the present disclosure has been described in detail with reference to only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to these disclosed embodiments. Rather, the present disclosure may be modified to include any number of variations, alterations, substitutions, or equivalent arrangements not previously described but commensurate with the scope of the present disclosure. Additionally, although various embodiments of the present disclosure have been described, it should be understood that aspects of the present disclosure may include only some of the described embodiments or combinations of various embodiments. Therefore, the present disclosure should not be considered to be limited by the foregoing description.

Claims

1. A method for controlling a brushed DC motor, comprising: determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining a torque command signal based on the speed difference signal; determining a voltage command based on the torque command signal; as well as applying a DC voltage to the brushed DC motor based on the voltage command, Wherein, determining the torque command signal based on the speed difference signal further comprises at least one of the following: determining a modified proportional torque component, the modified proportional torque component comprising a product of a feed-forward gain term and the speed command signal, and wherein the torque command signal includes the modified proportional torque component; and A modified derivative torque component is determined, the modified derivative torque component comprising a time derivative of a motor speed of the brushed DC motor, and wherein the torque command signal includes the modified derivative torque component.

2. The method according to claim 1, wherein Determining the torque command signal based on the speed difference signal includes determining the modified proportional torque component, the modified proportional torque component comprising the product of the feedforward gain term and the speed command signal, and wherein the torque command signal includes the modified proportional torque component.

3. The method according to claim 2, further comprising: The feedforward gain term is determined so that the brushed DC motor meets a given bandwidth.

4. The method according to claim 3, wherein: The feedforward gain term is determined according to the following formula: Among them, K f is the feedforward gain term, K i is the integral gain term, K p is the proportional gain term, and a is the given bandwidth.

5. The method according to claim 1, wherein Determining the torque command signal based on the speed difference signal includes determining the modified derivative torque component, the modified derivative torque component including the time derivative of the motor speed of the brushed DC motor, and wherein the torque command signal includes the modified derivative torque component.

6. The method according to claim 1, further comprising: determining a position-dependent torque component based on the position of the brushed DC motor, and The torque command signal includes the position-related torque component.

7. The method according to claim 6, wherein: The position-dependent torque component is also based on the operating direction of the brushed DC motor.

8. The method according to claim 6, wherein: Determining the position-dependent torque component includes using a lookup table to determine the position-dependent torque component based on a position of the brushed DC motor.

9. The method according to claim 1, further comprising: determining a limited torque command signal based on the torque command signal to satisfy at least one of: a supply current limit value, a motor current limit value, and a maximum available voltage value, and Wherein, determining the voltage command further comprises: determining the voltage command based on the limited torque command signal.

10. The method according to claim 9, wherein: Determining the limited torque command signal based on the torque command signal further includes at least one of the following: determining a capacity limit value different from the supply current limit value based on a nonlinear function of the supply current limit value, and determining the limited torque command signal based on the capacity limit value; as well as The limited torque command signal is calculated based on a nonlinear function of the supply current limit value.

11. A motor control system comprising: Brushed DC motors have sets of brushes; a voltage regulator configured to apply a DC voltage to the brushed DC motor based on a voltage command; as well as The controller is configured as: determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining a torque command signal based on the speed difference signal; as well as determining the voltage command based on the torque command signal, Wherein, determining the torque command signal based on the speed difference signal includes at least one of the following: determining a modified proportional torque component, the modified proportional torque component comprising a product of a feed-forward gain term and the speed command signal, and wherein the torque command signal includes the modified proportional torque component; and A modified derivative torque component is determined, the modified derivative torque component comprising a time derivative of a motor speed of the brushed DC motor, and wherein the torque command signal includes the modified derivative torque component.

12. The motor control system according to claim 11, wherein: Determining the torque command signal based on the speed difference signal further includes determining the modified proportional torque component, the modified proportional torque component comprising the product of the feedforward gain term and the speed command signal, and wherein the torque command signal includes the modified proportional torque component.

13. The motor control system according to claim 12, wherein: The controller is further configured to determine the feed-forward gain term so that the brushed DC motor meets a given bandwidth.

14. The motor control system according to claim 13, wherein: The controller is further configured to determine the feedforward gain term according to the following equation: Among them, K f is the feedforward gain term, K i is the integral gain term, K p is the proportional gain term, and a is the given bandwidth.

15. The motor control system according to claim 11, wherein: Determining the torque command signal based on the speed difference signal includes determining the modified derivative torque component, the modified derivative torque component including the time derivative of the motor speed of the brushed DC motor, and wherein the torque command signal includes the modified derivative torque component.

16. The motor control system according to claim 11, wherein: The controller is further configured to determine a position-dependent torque component based on a position of the brushed DC motor, and wherein the torque command signal includes the position-dependent torque component.

17. The motor control system according to claim 16, wherein: The position-dependent torque component is also based on the operating direction of the brushed DC motor.

18. The motor control system according to claim 16, wherein: Determining the position-dependent torque component includes using a lookup table to determine the position-dependent torque component based on a position of the brushed DC motor.

19. The motor control system according to claim 11, wherein: The controller is further configured to determine a limited torque command signal based on the torque command signal to satisfy at least one of: a supply current limit value, a motor current limit value, and a maximum available voltage value, and Wherein, determining the voltage command further comprises determining the voltage command based on the limited torque command signal.

20. A method of operating a brushed DC motor to adjust a column position of a steering system in a vehicle, comprising: determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining a torque command signal based on the speed difference signal; determining a voltage command based on the torque command signal; as well as applying a DC voltage to the brushed DC motor based on the voltage command, Wherein, determining the torque command signal based on the speed difference signal further comprises at least one of the following: determining a modified proportional torque component, the modified proportional torque component comprising a product of a feed-forward gain term and the speed command signal, and wherein the torque command signal includes the modified proportional torque component; determining a modified derivative torque component, the modified derivative torque component comprising a time derivative of a motor speed of the brushed DC motor, and wherein the torque command signal includes the modified derivative torque component; and A position-dependent torque component is determined based on a position of the brushed DC motor, and wherein the torque command signal includes the position-dependent torque component.

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