DC motor voltage limiting control system and method based on brush voltage drop

Abstract

Technical solutions for controlling a brushed direct current (DC) motor are described, including: determining a brush voltage drop across a brush set of the brushed DC motor based on one of a motor current command or an actual motor current; determining, based on the brush voltage drop, at least one of: a first voltage limit that does not exceed a supply current limit based on a supply current value, and a second voltage limit that does not exceed a maximum available voltage based on a controller supply voltage value; determining a final voltage limit based on the at least one of the first voltage limit and the second voltage limit; determining a final voltage command based on the initial voltage command and the final voltage limit does not exceed the final voltage limit; and applying a DC voltage to the brushed DC motor based on the final voltage command.

Description

BACKGROUND

[0001] The present disclosure relates to methods and systems for operating a DC electric machine, such as a brushed DC electric machine. More specifically, the present disclosure relates to methods and systems for limiting voltage to a brushed DC electric machine to satisfy one or more operating constraints.

[0002] Brushed DC electric machines are used in a variety of applications. One such application of brushed DC electric machines is in the power steering system of a vehicle. Significant advantages of brushed DC electric machines over alternatives, such as AC electric machines, include low cost components, fewer electrical circuits, simplicity, and ease of control.

[0003] Active speed control techniques can be used with brushed DC electric machines to reduce noise and provide better customer performance. There are primarily two methods used to control speed: one method utilizes a speed-torque controller, and the other method utilizes a speed-voltage controller.

[0004] Several different operating constraints, such as available voltage, supply current limit, and electric machine current limit, can apply to the operation of a DC electric machine. SUMMARY

[0005] According to one or more embodiments, a method of controlling a brushed direct current (DC) electric machine includes determining a brush voltage drop across a brush set of the brushed DC electric machine based on one of a motor current command or an actual motor current; determining at least one of a first voltage limit based on a supply current value not exceeding a supply current limit, and a second voltage limit based on a controller supply voltage value not exceeding a maximum available voltage based on the brush voltage drop; determining a final voltage limit based on at least one of the first voltage limit and the second voltage limit; determining a final voltage command based on an initial voltage command and the final voltage command not exceeding the final voltage limit; and applying a DC voltage to the brushed DC electric machine based on the final voltage command.

[0006] According to one or more embodiments, a motor control system is provided. The motor system includes a brushed direct current (DC) electric machine having a brush set, a voltage regulator configured to apply a DC voltage to the brushed DC electric machine based on a voltage command, and a controller. The controller is configured to determine a brush voltage drop across the brush set of the brushed DC electric machine based on one of a motor current command or an actual motor current; determine at least one of a first voltage limit based on a supply current value not exceeding a supply current limit, and a second voltage limit based on a controller supply voltage value not exceeding a maximum available voltage based on the brush voltage drop; determine a final voltage limit based on at least one of the first voltage limit and the second voltage limit; determine a final voltage command based on an initial voltage command and the final voltage command not exceeding the final voltage limit; and transmit the final voltage command to the voltage regulator.

[0007] These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. BRIEF DESCRIPTION OF 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 are 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 is shown in accordance with various aspects of the present disclosure;

[0010] Figure 2 A schematic block diagram of a system for controlling a brushed DC motor is shown in accordance with various aspects of the present disclosure;

[0011] Figure 3 An electrical schematic diagram of a control system for a brushed DC motor is shown in accordance with various aspects of the present disclosure;

[0012] Figure 4 A schematic block diagram of a motor controller for operating a DC motor is shown in accordance with various aspects of the present disclosure;

[0013] Figure 5 A schematic diagram of a torque command generator of a motor controller is shown in accordance with various aspects of the present disclosure;

[0014] Figures 6A to 6C A plot showing speed, voltage command, and motor current of a DC motor respectively shown as being operated to satisfy a motor current limit on a common time scale is shown in accordance with various aspects of the present disclosure;

[0015] Figures 7A to 7C A plot showing speed, voltage command, and motor current of a DC motor respectively shown as being operated to satisfy a supply current limit on a common time scale is shown in accordance with various aspects of the present disclosure;

[0016] Figures 8A to 8B A plot showing speed and voltage command of a DC motor respectively shown as being operated to satisfy a supply voltage limit on a common time scale is shown in accordance with various aspects of the present disclosure; and

[0017] Figure 9 A flowchart listing steps in a method for operating a DC motor in accordance with various aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0018] Reference will now be made to the drawings wherein depicted specific embodiments of the disclosure will be described, but the disclosure is not limited to the specific embodiments depicted, it being understood that the disclosed embodiments are merely illustrative of the present disclosure, which can be embodied in various forms and alternative forms. The drawings are not necessarily to scale, with some features being exaggerated or minimized for the sake of clarity. The specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to employ the present disclosure in a variety of ways.

[0019] As used herein, the terms module and sub-module refer to one or more processing circuits, such as an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, combinational logic circuitry, and / or other suitable components that provide the described functionality. As can be appreciated, the sub-modules described below can be combined and / or further divided.

[0020] The present disclosure provides an anti-windup control strategy for a speed- voltage controller operating a brushed DC motor. The voltage can be limited to satisfy several different operating constraints. The present disclosure addresses three such operating constraints, including a maximum available voltage, a supply current limit, and a motor current limit. Equations are derived that relate these operating constraints to the maximum voltage and minimum voltage. The derivations vary with system state and provide both active limits and maximum capabilities.

[0021] In some embodiments, voltage limits corresponding to the maximum available voltage and the supply current limit can be determined based on brush voltage drops across brush sets of the brushed DC motor. The present disclosure provides for determining the brush voltage drops based on a motor current command or an actual motor current, and determining voltage limit values for the brushed DC motor corresponding to satisfying each of the supply current limit and the motor current limit based on the brush voltage drops. The systems and methods of the present disclosure, as compared to alternative techniques, such as techniques that assume a brush voltage drop to be constant with respect to motor current, and techniques that use an iterative solver to determine a root of a polynomial equation in order to determine a motor current limit corresponding to the maximum available voltage and the supply current limit. The systems and methods of the present disclosure are shown to provide enhanced output torque while satisfying operating constraints, and with significantly less computational burden as compared to alternative techniques that use an iterative solver.

[0022] Reference will now be made to the drawings wherein depicted specific embodiments of the disclosure will be described, but the disclosure is not limited to the specific embodiments depicted, it being understood that the disclosed embodiments are merely illustrative of the present disclosure, which can be embodied in various forms and alternative forms. The drawings are not necessarily to scale, with some features being exaggerated or minimized for the sake of clarity. The specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to employ the present disclosure in a variety of ways. Figure 1 An exemplary embodiment of a column position module (CPM) 20 of a steering system in a vehicle is shown, which can utilize the disclosed systems and methods to control a DC motor.

[0023] CPM 20 includes a steering shaft 22 configured to be attached to a steering wheel, which can also be referred to as a hand wheel, which a person can use to steer the vehicle. CPM 20 includes a steering actuator 24 attached to the steering shaft. Steering actuator 24 can supplement the force applied by the person to provide a power assisted steering function. CPM 20 also includes a tilt actuator motor 26 configured to control the vertical position of the hand wheel by moving the end of the steering shaft in a radial direction. CPM 20 also includes a telescoping actuator motor 28 (not shown in Figure 1

[0024] Any or all of steering actuator 24, tilt actuator motor 26, and / or telescoping actuator motor 28 can include a brushed DC motor and can be controlled using the systems and methods of the present disclosure. However, the systems and methods of the present disclosure can be used with brushed DC motors in other applications in vehicles, such as for window or lock actuators. The systems and methods of the present disclosure are not limited to use in vehicles and can be used with brushed DC motors in a variety of different applications.

[0025] Figure 2 A schematic block diagram of a system 50 for controlling DC motors 26, 28 is shown. In some embodiments, and as shown in Figure 2

[0026] ​​The system 50 includes a controller 60. The controller 60 can include any suitable controller, such as an electronic control unit or other suitable controller. The controller 60 can be configured to control, for example, various functions of the steering system and / or various functions of the vehicle. The controller 60 can include a processor 62 and a memory 64. The processor 62 can include any suitable processor, such as the processors described herein. Additionally or alternatively, the controller 60 can include any suitable number of processors in addition to or different from the processor 62. The memory 64 can include a single disk, multiple disks (e.g., hard drives), and / or electronic non-volatile computer memory storage media such as a flash memory device. In some embodiments, the memory 64 can include flash memory, semiconductor (solid-state) memory, or the like. The memory 64 can include random access memory (RAM), read only memory (ROM), or a combination thereof. The memory 64 can include instructions that, when executed by the processor 62, cause the processor 62 to control at least various aspects of the vehicle. Additionally or alternatively, the memory 64 can include instructions that, when executed by the processor 62, cause the processor 62 to perform functions associated with the systems and methods described herein.

[0027] The controller 60 can be operably connected to a voltage regulator 52. The voltage regulator 52 can be configured to apply a DC voltage v to the first brush 30 of the DC motor 26, 28. The voltage regulator 52 can generate the DC voltage v based on a voltage command v cmd from the controller 60.

[0028] In some embodiments, as Figure 2 shown, the system 50 can include a current sensor 54 configured to measure a DC current applied to the DC motor 26, 28 and transmit a motor current signal i m to the controller 60, the motor current signal representing an actual motor current in a winding of the DC motor 26, 28. Additionally or alternatively, as Figure 2 shown, the system 50 can include a position sensor 56 configured to measure a rotational position of the DC motor 26, 28 and transmit a motor position signal ω m to the controller 60.

[0029] In some embodiments, the controller 60 can perform the methods described herein. However, the performance of the methods described herein by the controller 60 is not meant to be limiting, as any type of software executing 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.

[0030] Figure 3 An electrical schematic diagram of a control system for brushed DC motors 26 and 28 is shown. As shown, the controller 60 and DC motors 26 and 28 define a supply current of i. S The voltage circuit, and defines the battery voltage V across the power supply (not shown). BATT The controller power supply voltage V at both ends of the controller 60 ECU .like Figure 3 As shown, the voltage loop includes the battery harness resistor R in the current path between the battery and the controller 60. BH The voltage loop also includes the controller input resistor R within the controller 60. C Its relationship with the battery harness resistance R BH Series connection. Figure 3 The DC motors 26 and 28 shown include an inductor, a resistor and a voltage source connected in series, representing the winding inductance, coil resistance and back electromotive force, respectively.

[0031] Figure 4 A schematic block diagram of a motor controller 70 for operating a DC motor according to various aspects of this disclosure is shown. The motor controller 70 is configured as a speed-voltage controller. However, the principles of this disclosure can be applied to other controller configurations.

[0032] The motor controller 70 includes a subtractor 72 configured to receive a speed command signal ω. ref Subtract motor speed ω m And calculate the speed command signal ω. ref With motor speed ω m The velocity difference signal ω between them diff The motor controller 70 also includes a voltage command generator 74, which is configured to generate a voltage command based on the speed difference signal ω. diff To generate the initial voltage command v ctrl The voltage command generator 74 can also be referred to as a voltage controller. The voltage command generator 74 can use a proportional-integral (PI) control loop to generate the initial voltage command v. ctrl However, other control techniques can be used, such as proportional-integral-derivative (PID) control loops or lookup tables.

[0033] The motor controller 70 also includes a voltage limiter 76, which is configured to respond to an initial voltage command v. ctrl To generate the final voltage command v cmd The voltage limiter 76 also takes three operating constraints as inputs for operating the DC motors 26 and 28, including: motor current limit I. MAX Supply current limit value I slim ; and the maximum available voltage value VMAX,Avl .

[0034] The voltage limiter 76 also generates an anti-windup signal AW that indicates the final voltage command v cmd is limited to cause the DC motor 26, 28 to satisfy at least one of the operating constraints I MAX , I slim , V MAX . The anti-windup signal AW is applied from the voltage limiter 76 to the voltage command generator 74.

[0035] The following equations (1)-(2) show a mathematical model of a DC motor. 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-EMF constant, J is the inertia of the motor, ω is the motor speed, τ e is the generated electrical torque, and τ LF is the load plus friction torque.

[0036] The following equation (3) describes the brush voltage drop v b due to the brushes 30, 32. V0 is a brush voltage parameter of the motor, and I0 is a current parameter of the motor.

[0037] The brush voltage drop v b occurs in the direction of the motor current i, as described in equation (3).

[0038] The generated electrical torque τ e is directly related to the DC motor current, as described in equation (4). τ e = Ki (4)

[0039] The following equation (5) provides a general method for calculating an initial voltage command v m from an actual mechanical speed ω ref and a reference speed ω cmd using a proportional-integral (PI) control loop. v cmd = K p (ω ref - ω m ) + K i ∫(ω ref - ω m )dt (5) where K p represents a proportional gain value, and K i represents an integral gain value. The proportional gain value K pand / or integral gain value K i Either or both of them can be constants.

[0040] This disclosure provides three different operating constraints for DC motors 26 and 28, which can be used for anti-saturation functionality of the PI control loop described in equation (5). These operating constraints include: motor current limit value I MAX Supply current limit I slim ; and the maximum available voltage V MAX .

[0041] Voltage commands can be limited to satisfy each of these operational constraints. The following sections provide derivations of the maximum and minimum voltages based on these constraints. Table I below lists the motor parameters used to verify the methods and systems of this disclosure. Voltage-mode operation can be used with the speed-voltage controller poles set to -20. Parameter Symbol Value Resistance R 0.833602905 Ω Inductance L 0.8 mH BEMF constant K 0.030281067 V.s / rad Brush voltage parameter [VO] 4.1472V Brush current parameter [io] 12A Inertia J 1.0581 x 10 -5 kg / m 2 ]]> Viscosity constant B 0.000545 Nms / rad Table I: Parameter values

[0042] Figure 5 A schematic diagram of the torque command generator 74 of the motor controller 70 is shown. The torque command generator 74 can implement the PI control loop as described in equation (5). The torque command generator 74 includes a first gain block 82, which is configured to convert the speed difference signal ω diff With proportional gain value K p Multiplication. The voltage command generator 74 also includes an adder 84, which is configured to calculate the initial voltage command v based on the output of the first gain block 82. ctrl .

[0043] The voltage command generator 74 also includes an integrator 86, which is configured to calculate the speed difference signal ω. diff The voltage command generator 74 also includes a second gain block 88, which is configured to integrate the speed difference signal ω. diff The integral and integral gain value K i Multiplication. The output of the second gain block 88 is provided to the adder 84, which calculates the initial voltage command v based on the sum of the outputs of the first gain block 82 and the second gain block 88. ctrl .

[0044] In some embodiments, such as Figure 5 As shown, an anti-saturation signal AW is provided to integrator 86. Integrator 86 can pause operation in response to receiving the anti-saturation signal AW, indicating a final voltage command based on voltage limits to satisfy operating constraint I. MAX I slim V MAXat least one of the maximum motor current limit I

[0045] the maximum motor current limit I MAX_im the minimum motor current limit -I MIN_im , each based on a motor current i MAX that does not exceed the maximum motor current value I MAX the maximum motor current limit I MAX_im and the minimum motor current limit -I MIN_im as described in equations (6) and (7):

[0046] Figures 6A to 6C A plot showing speed, voltage command, and motor current of DC motor 26, 28 operating in accordance with satisfying the motor current limit I MAX of 4.0 amperes (A) is shown on a unified time scale. Figure 6A includes a first plot 102 showing a speed command signal ω ref (also referred to as a reference speed), and a second plot 104 showing a motor speed ω m (also referred to as an actual motor speed).

[0047] the final voltage command v cmd is limited based on the maximum motor current limit voltage v MAX_im and the minimum motor current limit voltage v MIN_im from equations (6) and (7), respectively, to cause the DC motor 26, 28 to satisfy the motor current limit I MAX of 4.0 A in regions of the reference speed above 2115 rpm and below -2115 rpm. These cause the final voltage command v cmd to be limited such that the system 50 satisfies one or more operational constraints can be referred to as an anti-windup region.

[0048] Figure 6B includes a third plot 106 of the final voltage command v cmd , where a first line 108 shows the maximum motor current limit voltage v MAX corresponding to the DC motor 26, 28 operating in the positive speed direction while satisfying the positive motor current limit I MAX_im of +4.0 A. Figure 6B also includes a second line 110 showing the minimum motor current limit voltage v MAX corresponding to the DC motor 26, 28 operating in the negative speed direction while satisfying the negative motor current limit -I MIN_imIf the actual motor current i reaches ±4 A at the beginning of the anti-saturation and stays at this limit throughout the anti-saturation region, then this limit method can be verified.

[0049] Figure 6C A fourth curve 112 including the motor current i, a first line 114 showing the motor current limit I MAX for positive polarity (i.e., forward operation) and a second line 116 showing the negative motor current limit -I MAX . Figure 6C The exact behavior of the motor current i is shown and the proper limits of the maximum motor current I MAX , -I MAX are verified.

[0050] At the ECU voltage V ECU , the supply current limit I slim limits the power delivered or absorbed by the battery. The motor power equation can be written as described in equation (8):

[0051] Under the limit condition that the supply current is = the supply current limit I slim , this relationship can be described by equation (9): Here, R c is the controller resistance, I MS is the maximum motor current for the supply current limit I slim , and V MS is the maximum motor voltage at the supply current limit I slim .

[0052] An alternative controller can neglect or simplify the brush voltage drop v b term to solve for I MS . One such alternative design assumes that the brush voltage drop v b is equal to the brush voltage parameter V0 and has a constant value, thereby neglecting the exponential term. This simplification can lead to several problems. For small motors, these two terms can be much larger than expected. On the other hand, if the value of the supply current is reduced due to some adverse condition, then the maximum motor current I MS cannot be considered high compared to the brush current I0. Thus, the brush voltage drop v b considered under such conditions can lead to a lower I MS . This can be especially problematic under adverse conditions when maximum possible torque is expected while satisfying the operating constraints. A conventional method can use equation (9) to base the supply current value I sNot exceeding the supply current limit I slim To determine the voltage limit, use equation (9) based on the supply current value I. s Not exceeding the supply current limit I slim Determining voltage limits may require iterative methods. However, such iterative methods can be computationally expensive and costly.

[0053] This invention provides an alternative technique for using a power supply current value I. s Not exceeding the supply current limit I slim This technique determines the voltage limit and does not require an iterative solver. The actual motor current i can be used to calculate the brush voltage drop v. b And the brush voltage drop v b It can be used to solve for supply current limitations I. slim The corresponding maximum motor current I MS Therefore, the first step is to use equation (3) to find the brush voltage drop v under specific conditions. b Considering the brush voltage drop v b Equation (9) can be rewritten as equation (10):

[0054] Maximum voltage v based on supply current MAX_is and the minimum voltage v based on the supply current MAX_is Each is based on a supply current limit of I. slim The supply current value I s I can be limited according to the supply current. slim The two solutions to equation (10) are used to calculate the maximum voltage v based on the supply current. MAX_is and the minimum voltage v based on the supply current MIN_is As described in equations (11) and (12):

[0055] This method may have some drawbacks. If the brush voltage drop is v... b The proposed method is not significant during the constraint period, but provides a solution very close to the actual solution of equation (9) under all conditions. The solution of the proposed method is only significant during the brush voltage drop v. b Very significant and the actual current is far from I MS Only then does it deviate from the actual solution. However, even with a significant brush voltage drop v b In the case where the motor current approaches its maximum value I MS The proposed solution is very close to the actual solution, and appropriate constraints are ensured when necessary.

[0056] Figures 7A to 7CThe operation is shown separately on a uniform time scale to meet the supply current limit I. slim The graphs show the speed, voltage command, and motor current of DC motors 26 and 28 with a power of 3.0 amperes (A). Figure 7A Includes the speed command signal ω ref The fifth curve 122 (also known as the reference speed), and the motor speed ω are shown. m The sixth curve, 124, (also known as the actual motor speed).

[0057] Final voltage command v cmd Based on the maximum voltage v based on the supply current from equations (11) and (12) respectively. MAX_is and the minimum voltage v based on the supply current MIN_is To limit the supply current I of controller 60 in the region above 2012 rpm and below -2012 rpm. slim .

[0058] Figure 7B Including the final voltage command v cmd The seventh curve 126, where the first line 128 shows the condition of satisfying the motor current limit I. MAX The controller 60, which operates simultaneously in the positive velocity direction, corresponds to the maximum voltage v based on the supply current. MAX_is . Figure 7B It also includes a second line 130, which indicates that the motor current limit I is met. MAX The minimum voltage v corresponding to DC motors 26 and 28 operating in the negative velocity direction. MIN_is .

[0059] Figure 7C Including supply current i s The eighth curve 132, the first line 134, and the second line 136, where the first line 134 shows the 3.0A supply current limit I for positive polarity (i.e., forward operation). slim The second line 136 shows a negative supply current limit of -3.0A for negative polarity (i.e., reverse operation) -I. slim . Figure 7C The supply current i is shown s The determined action and verification of the supply current limit I slim -I slim Appropriate restrictions.

[0060] Based on the maximum available voltage V MAX，Avl Determining the voltage command limit is relatively straightforward and can be calculated as shown in equations (13)-(14); V MAX_vs =V MAX，Avl (13) V MIN-vs = -V MAX，Avl (14) where V MAX_vs and V MIN_vs are the maximum and minimum voltages that can be supplied to the DC motor, respectively, taking into account the maximum available voltage constraint V MAX，Avl .

[0061] The maximum available voltage V MAX，Avl is not necessarily equal to the controller supply voltage V ECU , as the full battery or controller supply voltage V ECU may not be available when applying the controller 60 to the DC motor 26, 28. Furthermore, to enhance robustness and simplicity of operation, zero values are not used as maximum or minimum limits at any point.

[0062] Figures 8A to 8B A plot of speed and voltage commands of the DC motor 26, 28 is shown, respectively, showing operation to satisfy the maximum available voltage (also referred to as supply voltage limit) V MAX，Avl of 13.5 V on a unified time scale. Figure 8A The plot includes a ninth curve 142 showing the speed command signal ω ref (also referred to as reference speed), and a tenth curve 144 showing the motor speed ω m (also referred to as actual motor speed).

[0063] The final voltage command v cmd is limited based on the supply voltage based maximum voltage v MAX_vs and the supply voltage based minimum voltage v MIN_vs from equations (13) and (14), respectively, to enable the controller 60 to satisfy the supply voltage limit of 13.5 V in the region above 2548 rpm and below -2548 rpm.

[0064] Figure 8B The plot includes an eleventh curve 146 including the final voltage command v cmd , where a first line 148 shows the supply voltage based maximum voltage v MAX_vs corresponding to the controller 60 operating to satisfy the supply voltage limit of 13.5 V while operating in the positive speed direction. Figure 8B The plot also includes a second line 150 showing the minimum voltage v MIN_vs corresponding to the controller 60 operating to satisfy the supply voltage limit of 13.5 V while operating in the negative speed direction.

[0065] All three sets of maximum and minimum voltage limits from the three constraints of the system are combined to find the final maximum voltage v for the controller using the following equations (15)-(16). MAX_final and the final minimum voltage v MIN_final : v MAX-final =min(v MAX_im v MAX_is ,v MAX-vs (15) v MIN_final =max(v MIN_im v MIN_is v MIN_vs (16) Where min is the maximum voltage v returned. MAX_im v MAX_is v MAX_vs The lowest value (i.e., The minimum function of (one of the maximum voltages with the lowest value), and max is the function that returns the minimum voltage v. MIN_im v MIN_is v MIN_vs The maximum function of the highest value (i.e., one of the minimum voltages with the highest value).

[0066] The following equations (17)-(18) describe the determination of the final voltage command v by the voltage limiter 76. cmd voltage command v cmd This limitation: v ctrl ≥v MAX_final ;v cmd =v MAX_final integrator(ω) ref -ω)=0 (17) v ctrl ≤v MIN_final ;v cmd =v MIN_final integrator(ω) ref -ω)=0 (18)

[0067] Once the initial voltage command v ctrl Exceeding these limits (i.e., if the initial voltage command v) ctrl Greater than the final maximum voltage v MAX_final or less than the final minimum voltage v MIN_final The voltage limiter 76 can then generate an anti-saturation signal AW, which indicates the final voltage command v. cmdis limited. In response to the anti-windup signal AW, the integrator 86 can pause operation. For example, the anti-windup signal AW can cause the integrator 86 to output a zero signal. Thus, in response to the anti-windup signal AW, the integrator 86 will stop at the previous value it obtained, and resume operation once the system 50 moves out of the anti-windup region.

[0068] In some embodiments, a current command i cmd may be used in place of the actual motor current i b for calculating the brush voltage drop v cmd . For example, the current command i cmd may be calculated based on a final voltage command v m and one or more parameters of the DC motor 26, 28, such as inductance, coil resistance, and back-EMF. In the event that the motor current measurement i cmd becomes unavailable, this current command i b may be used to calculate the brush voltage drop v cmd .

[0069] Figure 9 A flowchart showing steps of a method 200 for operating a DC motor according to various aspects of the present disclosure is shown. The method 200 can be performed by the motor controller 70 of the present disclosure. It is understood in accordance with the present disclosure that the order of operations within the method is not limited to the order shown in Figure 9 , but can be performed in one or more varied orders in accordance with the present disclosure, as applicable.

[0070] At 202, the method 200 determines a brush voltage drop across a brush set of a brushed DC motor based on one of a motor current command or an actual motor current. For example, the processor 62 can execute instructions to calculate the brush voltage drop v b using Equation (3) based on the motor current command i cmd or based on a motor current signal i m representing a measured value of the actual motor current i .

[0071] At 204, the method 200 determines at least one of a first voltage limit based on a supply current value not exceeding a supply current limit, and a second voltage limit based on a controller supply voltage value not exceeding a maximum available voltage, based on the brush voltage drop. For example, the processor 62 can execute instructions and use the corresponding equations of Equation (11), Equation (12), Equation (13), and / or Equation (14) to calculate a maximum voltage v MAX_is based on the supply current, a minimum voltage v MIN_is based on the supply current, a maximum voltage v MAX_vs based on the supply voltage, and / or a minimum voltage v MIN_vs based on the supply voltage.

[0072] At 206, the method 200 determines a final voltage limit based on at least one of the first voltage limit and the second voltage limit. For example, the processor 62 can execute instructions to calculate a final maximum voltage v MAX_final and / or a final minimum voltage v MIN_final as described in equations (15)-(16).

[0073] At 208, the method 200 determines an initial voltage command based on a difference between a speed of the brushed DC motor and a speed command signal. For example, the processor 62 can execute instructions to implement the voltage command generator 74 to generate an initial voltage command v diff based on the speed difference signal ω ctrl .

[0074] At 210, the method 200 determines a final voltage command based on the initial voltage command and the final voltage command does not exceed the final voltage limit. For example, the processor 62 can execute instructions to implement the voltage limiter 76 to generate a final voltage command v ctrl based on the initial voltage command v cmd and cause the final voltage command v cmd not to exceed a final maximum voltage v MAX_final and / or a final minimum voltage v MIN-final .

[0075] At 212, the method 200 applies a DC voltage to the brushed DC motor based on the voltage command. For example, the voltage regulator 52 can generate a DC voltage v cmd and apply the DC voltage v cmd to the first brush 30 of the DC motor 26, 28, where the DC voltage v cmd is based on the voltage command v cmd from the controller 60.

[0076] The present disclosure provides a method of controlling a brushed direct current (DC) motor. The method includes determining a brush voltage drop across a brush set of the brushed DC motor based on one of a motor current command or an actual motor current; determining at least one of a first voltage limit based on a supply current value not exceeding a supply current limit and a second voltage limit based on a controller supply voltage value not exceeding a maximum available voltage based on the brush voltage drop; determining a final voltage limit based on at least one of the first voltage limit and the second voltage limit; determining a final voltage command based on an initial voltage command and the final voltage command does not exceed the final voltage limit; and applying a DC voltage to the brushed DC motor based on the final voltage command.

[0077] In some embodiments, the method further includes determining the initial voltage command based on a difference between a speed command signal and a speed of the brushed DC motor.

[0078] In some embodiments, determining the brush voltage drop includes based on a nonlinear equation. To calculate the brush voltage drop, where v b I is the brush voltage drop, i is either the motor current command or the actual motor current, V0 is the brush voltage parameter, and I0 is the brush current parameter.

[0079] In some embodiments, the final voltage limit is based on the first voltage limit.

[0080] In some embodiments, determining the final voltage limit includes calculating the first voltage limit based on at least one of the following: according to Maximum voltage limit (V) MAX ), or according to Minimum voltage limit (V) MIN ), where K is the back electromotive force constant of the brushed DC motor, ω is the speed of the brushed DC motor, and v b It is the brush voltage drop, R is the winding resistance of the brushed DC motor, V ECU It is the controller power supply voltage, I slim It is the supply current limit, and R c It is the controller resistor.

[0081] In some embodiments, the final voltage limit is based on a second voltage limit, and determining the final voltage limit includes calculating the second voltage limit based on at least one of the following: according to v MAX =V MAX，Avl Maximum voltage limit (V) MAX ), or according to v MIN =-V MAX，Avl Minimum voltage limit (V) MIN ), where V MAX，Avl That is the maximum available voltage.

[0082] In some embodiments, the method further includes: determining a third voltage limit based on the motor current not exceeding a maximum motor current value, and determining a final voltage limit includes further determining a final voltage limit based on the third voltage limit.

[0083] In some embodiments, the method further includes: integrating a value used to determine an initial voltage command; and pausing the integration of the value in response to setting a final voltage command based on a final voltage limit.

[0084] In some embodiments, determining the final voltage limit includes determining a first maximum voltage limit based on the supply current value not exceeding the supply current limit, determining a second maximum voltage limit based on the controller supply voltage value not exceeding the maximum available voltage, determining the final maximum voltage limit based on a lowest one of a plurality of maximum voltage limits including at least the first maximum voltage limit and the second maximum voltage limit, determining a first minimum voltage limit based on the supply current value not exceeding the supply current limit, determining a second minimum voltage limit based on the controller supply voltage value not exceeding the maximum available voltage, and determining the final minimum voltage limit based on a highest one of a plurality of minimum voltage limits including at least the first minimum voltage limit and the second minimum voltage limit. In some embodiments, the final voltage limit includes each of the final maximum voltage limit and the final minimum voltage limit.

[0085] In some embodiments, the brushed DC motor is an actuator motor configured to control a position of a hand wheel of a steering system in a vehicle.

[0086] The present disclosure provides a motor control system. The motor control system includes a brushed direct current (DC) motor having a brush set, 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 brush voltage drop across the brush set of the brushed DC motor based on one of a motor current command or an actual motor current, determine at least one of a first voltage limit based on a supply current value not exceeding a supply current limit and a second voltage limit based on a controller supply voltage value not exceeding a maximum available voltage based on the brush voltage drop, determine a final voltage limit based on at least one of the first voltage limit and the second voltage limit, determine a final voltage command based on the initial voltage command and the final voltage command not exceeding the final voltage limit, and transmit the final voltage command to the voltage regulator.

[0087] In some embodiments, the controller is further configured to determine the initial voltage command based on a difference between a speed command signal and a speed of the brushed DC motor.

[0088] In some embodiments, the controller is further configured to calculate the brush voltage drop according to where v is the brush voltage drop, i is one of the motor current command or the actual motor current, and V0 is a brush voltage parameter and I0 is a brush current parameter. b is the brush voltage drop, i is one of the motor current command or the actual motor current, and V0 is a brush voltage parameter and I0 is a brush current parameter.

[0089] In some embodiments, the final voltage limit is based on the first voltage limit.

[0090] In some embodiments, the controller is further configured to calculate the first voltage limit based on at least one of: Maximum voltage limit (V) MAX ), or according to Minimum voltage limit (V) MIN ), where K is the back electromotive force constant of the brushed DC motor, ω is the speed of the brushed DC motor, and v b It is the brush voltage drop, R is the winding resistance of the brushed DC motor, V ECU It is the controller power supply voltage, I slim It is a supply current limit, and R c It is the controller resistor.

[0091] In some embodiments, the final voltage limit is based on the second voltage limit, and the controller is further configured to calculate the second voltage limit based on at least one of the following: according to v MAX =V MAX，Avl Maximum voltage limit (V) MAX ), or according to v MIN =-V MAX，Avl Minimum voltage limit (V) MIN ), where V MAX，Avl That is the maximum available voltage.

[0092] In some embodiments, the controller is further configured to determine a third voltage limit based on the motor current not exceeding the maximum motor current value, and the controller is further configured to determine a final voltage limit based on the third voltage limit.

[0093] In some embodiments, the controller is further configured to: integrate the value used to determine the initial voltage command; and suspend the integration of the value in response to setting the final voltage command based on the final voltage limit.

[0094] In some embodiments, the controller is further configured to: determine a first maximum voltage limit based on a supply current value not exceeding a supply current limit; determine a second maximum voltage limit based on a controller supply voltage value not exceeding a maximum available voltage; determine a final maximum voltage limit based on the lowest of a plurality of maximum voltage limits including at least the first and second maximum voltage limits; determine a first minimum voltage limit based on a supply current value not exceeding a supply current limit; determine a second minimum voltage limit based on a controller supply voltage value not exceeding a maximum available voltage; and determine a final minimum voltage limit based on the highest of a plurality of minimum voltage limits including at least the first and second minimum voltage limits. In some embodiments, the final voltage limit includes each of the final maximum voltage limit and the final minimum voltage limit.

[0095] In some embodiments, the brushed DC motor is an actuator motor configured to control the position of the handwheel of the steering system in a vehicle.

[0096] While the present disclosure has been described in detail with respect to only a limited number of embodiments, it should be appreciated that the present disclosure is not limited to these disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of changes, alterations, substitutions, or equivalent arrangements not heretofore described without departing from the spirit and scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure can include only some of the described embodiments, or a combination of some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description.

Claims

1. A method for controlling a brushed DC motor, comprising: The brush voltage drop on the brush group of the brushed DC motor is determined based on either the motor current command or the actual motor current. Based on the brush voltage drop, at least one of the following is determined: a first voltage limit based on the supply current value not exceeding the supply current limit, and a second voltage limit based on the controller supply voltage value not exceeding the maximum available voltage; The final voltage limit is determined based on at least one of the first voltage limit and the second voltage limit; The final voltage command is determined based on the initial voltage command, and the final voltage command does not exceed the final voltage limit. as well as The DC voltage is applied to the brushed DC motor based on the final voltage command.

2. The method according to claim 1, further comprising: The initial voltage command is determined based on the difference between the speed of the brushed DC motor and the speed command signal.

3. The method according to claim 1, wherein, Determining the brush voltage drop includes using nonlinear equations To calculate the brush voltage drop, where v b I is the brush voltage drop, i is either the motor current command or the actual motor current, V0 is the brush voltage parameter, and I0 is the brush current parameter.

4. The method according to claim 1, wherein, The final voltage limit is based on the first voltage limit.

5. The method according to claim 4, wherein, Determining the final voltage limit includes calculating the first voltage limit based on at least one of the following: according to Maximum voltage limit (V) MAX ), or according to Minimum voltage limit (V) MIN ), Where K is the back electromotive force constant of the brushed DC motor, ω is the speed of the brushed DC motor, and v b R is the brush voltage drop, and V is the winding resistance of the brushed DC motor. ECU It is the controller power supply voltage, I slim It is the aforementioned supply current limit, and R c It is the controller resistor.

6. The method according to claim 1, wherein, The final voltage limit is based on the second voltage limit, and Determining the final voltage limit includes calculating the second voltage limit based on at least one of the following: according to v MAX =V MAX,Avl Maximum voltage limit (V) MAX ), or according to v MIN =-V MAX,Avl Minimum voltage limit (V) MIN ), where V MAX,Avl This is the maximum available voltage.

7. The method according to claim 1, further comprising: The third voltage limit is determined based on the motor current not exceeding the maximum motor current value, and Determining the final voltage limit includes: further determining the final voltage limit based on the third voltage limit.

8. The method according to claim 1, further comprising: Integrate the value used to determine the initial voltage command; as well as In response to the command to set the final voltage based on the final voltage limit, the integration of the value is paused.

9. The method according to claim 1, wherein, Determining the final voltage limit includes: The first maximum voltage limit is determined based on the fact that the supply current value does not exceed the supply current limit; The second maximum voltage limit is determined based on the controller power supply voltage value not exceeding the maximum available voltage; The final maximum voltage limit is determined based on the lowest of a plurality of maximum voltage limits, including at least the first maximum voltage limit and the second maximum voltage limit; A first minimum voltage limit is determined based on the supply current value not exceeding the supply current limit; A second minimum voltage limit is determined based on the controller supply voltage value not exceeding the maximum available voltage; and A final minimum voltage limit is determined based on the highest of a plurality of minimum voltage limits, including at least the first minimum voltage limit and the second minimum voltage limit, wherein the final voltage limit includes each of the final maximum voltage limit and the final minimum voltage limit.

10. The method according to claim 1, wherein, The brushed DC motor is an actuator motor configured to control the position of the handwheel of the steering system in a vehicle.

11. A motor control system, comprising: Brushed DC motor with brush assembly; A voltage regulator is configured to apply a DC voltage to the brushed DC motor based on a voltage command; as well as The controller is configured as follows: The brush voltage drop on the brush group of the brushed DC motor is determined based on either the motor current command or the actual motor current. Based on the brush voltage drop, at least one of the following is determined: a first voltage limit based on the supply current value not exceeding the supply current limit, and a second voltage limit based on the controller supply voltage value not exceeding the maximum available voltage; The final voltage limit is determined based on at least one of the first voltage limit and the second voltage limit; The final voltage command is determined based on the initial voltage command, and the final voltage command does not exceed the final voltage limit. as well as The final voltage command is transmitted to the voltage regulator.

12. The system according to claim 11, wherein, The controller is also configured to determine the initial voltage command based on the difference between the speed of the brushed DC motor and the speed command signal.

13. The system according to claim 11, wherein, The controller is also configured to: according to To calculate the brush voltage drop, where v b I is the brush voltage drop, i is either the motor current command or the actual motor current, V0 is the brush voltage parameter, and I0 is the brush current parameter.

14. The system according to claim 11, wherein, The final voltage limit is based on the first voltage limit.

15. The system according to claim 14, wherein, The controller is also configured to calculate the first voltage limit based on at least one of the following: Maximum voltage limit (V) MAX ), or according to Minimum voltage limit (V) MIN ), where K is the back electromotive force constant of the brushed DC motor, ω is the speed of the brushed DC motor, and v b R is the brush voltage drop, and V is the winding resistance of the brushed DC motor. ECU It is the controller power supply voltage, I slim It is the aforementioned supply current limit, and R c It is the controller resistor.

16. The system according to claim 11, wherein, The final voltage limit is based on the second voltage limit, and The controller is further configured to calculate the second voltage limit based on at least one of the following: according to v MAX =V MAX,Avl Maximum voltage limit (V) MAX ), or according to v MIN =-V MAX,Avl Minimum voltage limit (V) MIN ),in, V MAX,Avl This is the maximum available voltage.

17. The system according to claim 11, wherein, The controller is also configured to: determine a third voltage limit based on the motor current not exceeding the maximum motor current value, and The controller is configured to further determine the final voltage limit based on the third voltage limit.

18. The system according to claim 11, wherein, The controller is also configured to: Integrate the value used to determine the initial voltage command; and In response to the command to set the final voltage based on the final voltage limit, the integration of the value is paused.

19. The system according to claim 11, wherein, The controller is also configured to: The first maximum voltage limit is determined based on the fact that the supply current value does not exceed the supply current limit; The second maximum voltage limit is determined based on the controller power supply voltage value not exceeding the maximum available voltage; The final maximum voltage limit is determined based on the lowest of a plurality of maximum voltage limits, including at least the first maximum voltage limit and the second maximum voltage limit; A first minimum voltage limit is determined based on the supply current value not exceeding the supply current limit; The second minimum voltage limit is determined based on the controller power supply voltage value not exceeding the maximum available voltage; as well as A final minimum voltage limit is determined based on the highest of a plurality of minimum voltage limits, including at least the first minimum voltage limit and the second minimum voltage limit, wherein the final voltage limit includes each of the final maximum voltage limit and the final minimum voltage limit.

20. The system according to claim 11, wherein, The brushed DC motor is an actuator motor configured to control the position of the handwheel of the steering system in a vehicle.

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