Device and method for controlling a motor for electric power steering

Abstract

Device for controlling a motor (130) of an electric power steering system, the device comprising: a transceiver (210) designed to receive information about a steering angle and information about the motor (130) of the electric power steering and to send a control signal to the motor (130) of the electric power steering; a motor operation determination device (221) designed to detect a rack and pinion stroke range and, based on the received information about the steering angle and the electric power steering motor (130), to determine whether a motor limiting mode needs to be initiated or terminated; and a motor control signal generator (222) designed to generate a control signal according to the specified initiation or termination of the motor limiting mode, characterized by the fact that The motor operation determination device (221) is designed to calculate a position of the rack (109) based on information about the steering angle, and is designed to calculate the strength of a current supplied to the electric power steering motor (130) and an angular velocity of the electric power steering motor (130) based on information about the electric power steering motor (130).

Description

GENERAL STATE OF THE ART1. Field of the invention

[0001] The present disclosure relates to a device according to the preamble of claim 1 and a method according to the preamble of claim 10 for controlling a motor of an electric power steering system of the rack and pinion type and in particular a device and a method for controlling a motor of an electric power steering system which limits a rack stroke. 2. Description of the state of the art

[0002] A steering device is a device that allows a driver to change the direction of travel of a vehicle by turning a steering wheel, and is a device that assists the driver in driving a vehicle in a desired direction by changing the center of rotation of a front wheel of the vehicle. The steering device uses a power steering system, such as an electric power steering (EPS) device, to assist the driver.

[0003] An electric power steering (EPS) device of the rack and pinion type is designed to detect a torque applied by the driver to the steering wheel in order to output an electrical signal proportional to the torque, receive the electrical signal through an electronic control unit (ECU) and generate an auxiliary steering force proportional to it, thereby moving a rack in the axial direction to effect a steering movement.

[0004] When an external force acts on the vehicle (for example, when a small amount of auxiliary steering force is applied due to a small amount of friction between the vehicle and a road surface, in the case where a frictional force of the road surface is reduced due to foreign matter, the vehicle is moving, or the vehicle begins to move into the parked position, so that a frictional force between the vehicle and the road surface is drastically reduced from a static frictional force to a kinetic frictional force), the driver tends to turn the steering wheel until it hits the rack.

[0005] However, if the driver turns the steering wheel to the stop in such a rack-and-pinion electric power steering (EPS) system, a stopper of the rack will strike the end of a gearbox housing, and an impact due to the inertia of the rack will generate noise and vibration in the vehicle, causing mechanical damage and inconvenience to the driver.

[0006] A variable rack and pinion steering (VRS) system has recently been installed in a vehicle. The VRS reduces the steering rack travel to change the vehicle's maximum steering angle, thereby increasing or decreasing its turning radius. The VRS limits the maximum steering angle when installing tire chains, changing tire size, or replacing a shock absorber. Specifically, when tire chains are installed, the VRS prevents them from damaging the vehicle body, and when no tire chains are installed, it reduces the vehicle's minimum turning radius.

[0007] As described above, the task is to prevent the driver from turning the steering wheel to its maximum angle. The generic patent DE 10 2006 003 428 A1 deals with an electromechanical steering device and a method for implementing a software end stop in an electromechanical steering device. BRIEF SUMMARY OF THE INVENTION

[0008] The present disclosure was filed to solve the aforementioned problem and provides a device having the features of claim 1 and a method having the features of claim 10 for controlling a motor of an electric power steering system to limit a rack stroke.

[0009] Furthermore, the present disclosure provides a device and a method for preventing an impact of a rack stop and for preventing mechanical damage and noise to a vehicle by more easily limiting the rack stroke.

[0010] Furthermore, the present disclosure provides a device and a method for varying the limited rack stroke by detecting a steering angle of the vehicle and the operation of the electric power steering motor.

[0011] Technical problems solved by the present disclosure are not limited to the technical problems mentioned above, and other, unmentioned technical problems will be clearly understood by a person skilled in the art from the following description.

[0012] In view of the aforementioned aspects, a device for controlling an electric power steering motor, according to an embodiment of the present disclosure, comprises: a transceiver designed to receive information about a steering angle and information about an electric power steering motor and to send a control signal to the electric power steering motor; a motor operation determination device designed to detect a rack and pinion stroke range and, based on the received information about the steering angle and the electric power steering motor, to determine whether a motor limiting mode needs to be initiated or terminated; and a motor control signal generator designed to generate a control signal according to the determined initiation or termination of the motor limiting mode.The motor operation determination device is designed to calculate a position of the rack based on information about the steering angle, and is designed to calculate the strength of a current supplied to the electric power steering motor and an angular velocity of the electric power steering motor based on information about the electric power steering motor.

[0013] In view of the aforementioned aspects, a method for controlling an electric power steering motor, according to an embodiment of the present disclosure, includes: a transmit / receive step of receiving information about a steering angle and information about an electric power steering motor and sending a control signal to the electric power steering motor;a motor operation determination step of detecting a rack travel range and determining, based on the received information about the steering angle and the electric power steering motor, whether a motor limiting mode needs to be initiated or terminated, whereby a position of the rack is calculated based on the steering angle information, the magnitude of a current supplied to the electric power steering motor, and an angular velocity of the electric power steering motor are calculated based on the information about the electric power steering motor; and a motor control signal generation step of generating a control signal according to the determined initiation or termination of the motor limiting mode.

[0014] Other details of the present revelation can be found in the detailed description and the drawings.

[0015] As described above, according to the present disclosure it is possible to effectively limit the rack stroke, thereby preventing damage to the vehicle and providing a benefit to the driver.

[0016] Furthermore, the present disclosure results in stable control of the vehicle's motion when an external force is applied to it, while minimizing heterogeneity due to sudden changes in the vehicle's steering. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The foregoing and other aspects, features and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings, in which: Fig. 1 is a perspective view showing a rack-and-pinion electric power steering device; Fig. 2 a block diagram of a device for controlling a motor for electric power steering according to an embodiment of the present disclosure; Fig. 3 is a flowchart that represents a method for controlling a motor of an electric power steering system to initiate a motor limiting mode according to an embodiment of the present disclosure; Fig. 4 is a flowchart that represents a method for controlling a motor of an electric power steering system to terminate a motor limiting mode according to an embodiment of the present disclosure; and Fig. 5A and Fig. 5B diagrams are shown, which represent a method for initiating an engine limiting mode according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EXECUTION EXAMPLES

[0018] Preferred embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. The advantages and features of the present disclosure and methods for implementing it will become apparent by reference to embodiments of the present disclosure, as described in detail below in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided merely for the complete disclosure of the present disclosure and inform the person skilled in the art of the scope of protection of the present disclosure, and the present disclosure is defined only by the scope of protection of the accompanying claims.Throughout the entire description, the same or similar reference symbols denote the same or similar elements.

[0019] While the terms “first,” “second,” and the like may modify various elements, components, and / or parts, it is clear that such elements, components, and / or parts are not limited by the aforementioned terms. The aforementioned terms are used solely for the purpose of distinguishing one element, component, or part from other elements, components, or parts. Accordingly, it is clear that a first element, component, or part, as defined below, may be a second element, component, or part within the technical concept of this disclosure.

[0020] The terms used herein serve only to describe embodiments and are not intended to limit the present disclosure. Singular forms used herein are intended to include plural forms unless the context clearly indicates otherwise. The terms "comprises" and / or "includes" used herein refer to the presence of a disclosed component, step, operation, and / or element and do not exclude the presence of, or the possibility of adding, one or more other components, steps, operations, and / or elements.

[0021] The present disclosure will be described in more detail below with reference to the accompanying drawings.

[0022] Fig. Figure 1 is a perspective view showing a rack-and-pinion electric power steering device.

[0023] As in Fig. Figure 1 shows an electric power steering device of the rack and pinion type for a vehicle, generally designed to include a steering device 100 extending from a steering wheel 101 to wheels 108 on both sides, and an auxiliary force mechanism 120 for providing an auxiliary steering force to the steering device 100.

[0024] The steering device 100 is designed to include a steering shaft 102, one end of which is connected to the steering wheel 101 so that it rotates with the steering wheel 101, and the opposite end is connected via a pair of universal joints 103 to a pinion shaft 104. The pinion shaft 104 is connected via a rack and pinion mechanism 105 to a rack 109, and both ends of the rack 109 are connected via a tie rod 106 and a tie rod 107 to the wheels 108 of the vehicle.

[0025] The rack and pinion mechanism 105 includes a pinion drive 111 formed on the pinion shaft 104 and a rack and pinion drive 112 formed on one side of the outer circumferential surface of the rack 109 to engage with the pinion drive 111. When the driver turns the steering wheel 101, a torque is generated in the steering device 100, and the generated torque controls the direction of the wheels 108 via the rack and pinion mechanism 105 and the tie rod 106.

[0026] The auxiliary steering mechanism 120 is designed to include a torque sensor 121 for detecting a torque applied by the driver to the steering wheel 101 in order to output an electrical signal proportional to the detected torque, an electronic control unit (ECU) 123 for generating a control signal based on an electrical signal sent by the torque sensor 121, a motor 130 for generating an auxiliary steering force based on a control signal sent by the electronic control unit 123, and a belt-type power transmission device 140 for transmitting an auxiliary steering force generated by the motor 130 via a belt to the rack 109.

[0027] The rack-and-pinion electric power steering device is designed such that a torque generated by the rotation of the steering wheel 101 is transmitted to the rack 109 via the rack-and-pinion mechanism 105, and such that an auxiliary steering force, generated in the motor 130 according to the generated torque, is transmitted to the rack 109 via a ball screw by means of the belt-type power transmission device 140. This means that the rack 109 can be moved axially by a combination of the torque generated in the steering device 100 and the auxiliary steering force generated in the motor 130.

[0028] However, due to its mechanical properties, the rack 109 has a limited stroke range. This can cause an additional transmitted torque at the end of the stroke to impact other components, and in particular, can cause a rack stop to strike an end of the gearbox housing. This impact can lead to noise and vibration in the vehicle, causing discomfort for the driver and potentially resulting in mechanical damage.

[0029] In order to effectively prevent an impact of the rack stop, in addition to limiting the auxiliary steering force, it is therefore necessary to limit the amount of the auxiliary steering force by setting a stroke range of the rack and to specify the limit of the auxiliary steering force in a linear form depending on the position of the rack, and thus to carry out a control in such a way that an applied steering force does not exceed the limit.

[0030] Furthermore, in the case of the installation of tire chains on the wheels 108 or the use of wide tires, the maximum range of the rack travel can be limited by using a function of the variable rack travel (VRS) system to limit the amount of steering force such that the steering wheel 101 can be operated within a target steering angle that is smaller than a predetermined maximum steering angle, which can be provided by controlling the operation of the motor 130.

[0031] Although a rack-type EPS (R-EPS) in Fig. 1 as a device for electric power steering, the present disclosure can be applied to a hydraulic EPS, a steering-train EPS (C-EPS), a two-pinion EPS (DP-EPS) or the like.

[0032] Furthermore, the present disclosure can also be applied to a reaction motor of a steer-by-wire (SBW) steering device. That is, when a steering angle approaches a predetermined range of a rack travel, the rotation of the reaction motor can be electrically or physically locked so that the driver can feel the steering wheel locking.

[0033] Fig. Figure 2 is a block diagram of a device for controlling a motor 30 of an electric power steering system according to an embodiment of the present disclosure.

[0034] With reference to Fig. 2 can include a control device 200 of a motor 30 of an electric power steering system according to the present disclosure, a transmitter receiver 210 and a control unit 220 with a motor operation determining device 221 and a motor control signal generator 222.

[0035] In particular, the transmitter-receiver 210 can receive information about a steering angle and information about the motor 30 of the electric power steering, which is sent from a steering sensor 20 to the control device 200 of the motor 30 of the electric power steering, and can send a control signal to the motor 30 of the electric power steering.

[0036] When receiving information about a steering angle, the transmitter-receiver 210 can receive at least one of a torque signal generated by a torque sensor and a steering angle signal generated by a steering angle sensor.

[0037] The steering sensor 20 can be a torque sensor for measuring torque applied to the steering wheel by the driver, or a steering angle sensor for measuring the steering angle of the steering wheel; however, the steering sensor 20 is not limited to these functions and can be a sensor for measuring variables related to the movement of the rack. Furthermore, the steering sensor 20 can be a sensor provided in the housing of a gearbox that encloses the rack to detect the position of the rack.

[0038] Thus, the information about a steering angle, which is generated by the signal detected by the steering sensor 20, is sent via the transmitter receiver 210 to the control unit 220 and the position of the rack is thereby determined.

[0039] When receiving information about the motor 30 of the electric power steering, the transmitter-receiver 210 can receive at least one motor torque signal generated by a motor torque sensor provided in the motor 30 of the electric power steering and one motor speed signal generated by a motor position sensor and can send the same to the controller 220.

[0040] Furthermore, if a function of the system 10 for variable rack and pinion (VRS) is used in the case that tire chains are installed on the vehicle wheels or wide tires are used, the transmitter-receiver 210 can receive a modified rack and pinion range from the system 10 for variable rack and pinion (VRS) in order to subsequently send it to the controller 220.

[0041] The control unit 220 can include a motor operation determination device 221 for determining a rack stroke range from the information received by the variable rack stroke (VRS) system 10 and for determining, based on the received information about the steering angle and the electric power steering motor 30, whether a motor limiting mode needs to be initiated or terminated, and a motor control signal generator 222 for generating a control signal according to the determined initiation or termination of the motor limiting mode.

[0042] The motor operation determination device 221 of the control 220 can calculate the position of the rack based on the information about the steering angle and can calculate the strength of a current supplied to the motor 30 of the electric power steering and an angular velocity of the motor 30 of the electric power steering based on the information about the motor 30 of the electric power steering.

[0043] The motor operation control device 221 can also perform control such that a motor limiting mode is initiated when a steering angle is within a threshold range of a target angle for the rack and pinion stroke range.

[0044] More precisely, the motor limiting mode serves to stop the rotation of the electric power steering motor and can be achieved by switching off a three-phase switch of motor 30 of the electric power steering or by electronically fixing an angle of motor 30 of the electric power steering. The operation of the motor limiting mode is described below with reference to Fig. 5 described in more detail.

[0045] Furthermore, the motor operation determination device 221 of the control unit 220 can determine the direction of a steering angle signal and the direction of a driver torque signal and can calculate an angular velocity of the motor 30 of the electric power steering using a motor speed signal.

[0046] The motor operation control device 221 can perform a control to end the motor limiting mode if the direction of the steering angle signal matches the direction of the torque signal and if the direction of the calculated angular velocity does not match the direction of the motor torque signal in the motor limiting mode.

[0047] For example, it can be assumed that clockwise rotation is positive and counterclockwise rotation is negative. If a steering angle signal has a positive direction (clockwise), a torque signal has a positive direction, and the angular velocity of the electric power steering motor 30 has a negative direction, this means that the vehicle's steering angle is outside a threshold range of the target angle and is returning to a normal range where limiting the rack travel is not necessary. The motor limiting mode must therefore be deactivated.

[0048] Furthermore, if a steering angle signal has a negative direction (counterclockwise), a torque signal has a negative direction, and the angular velocity of the electric power steering motor 30 has a positive direction, this means that the vehicle's steering angle is outside a threshold range of the target angle and returns to the normal range. The motor limiting mode must therefore be deactivated.

[0049] This means that if the driver maintains the steering angle with a constant torque by operating the steering wheel, in a state where the steering angle reaches the threshold range in which rack travel limitation is required, the motor limiting mode is initiated, so that no auxiliary steering force from the electric power steering motor is applied. However, the rack may move back into the normal range, where rack travel limitation is not required, due to an alignment force from the tires or an elastic force from the tires. Consequently, since releasing the motor limiting mode is necessary in this case, the motor operation control device 221 can determine this and terminate the motor limiting mode as described above.

[0050] As described above, the motor operation control device 221 can automatically initiate or terminate the motor limiting mode using information obtained by sensing the vehicle's steering angle, the driver's torque signal, and the operation of the electric power steering motor 30.

[0051] The motor control signal generator 222 can generate a control signal to initiate or terminate the motor limiting mode and can send it via the transmitter receiver 210 to the system 10 for variable rack stroke and to the motor 30 of the electric power steering, thus enabling the limitation of the rack stroke.

[0052] Furthermore, the control device 200 of the motor 30 of the electric power steering described above can implement a control logic of the motor 30 of the electric power steering by using software without installing any hardware.

[0053] Fig. Figure 3 is a flowchart that represents a method for controlling a motor of an electric power steering system to initiate a motor limiting mode according to an embodiment of the present disclosure.

[0054] With reference to Fig. 3. A method for controlling a motor of an electric power steering system according to the present disclosure may include: a transmit / receive step of receiving information about a steering angle and information about a motor of an electric power steering system and sending a control signal to the motor of the electric power steering system; a motor operation determination step of detecting a rack travel range and determining, based on the received information about the steering angle and the motor of the electric power steering system, whether a motor limiting mode needs to be initiated or terminated; and a motor control signal generation step of generating a control signal according to the determined initiation or termination of the motor limiting mode.

[0055] Information about a steering angle is received in the transmit / receive step (S300), where at least one can be received from a torque signal generated by a torque sensor and a steering angle signal generated by a steering angle sensor.

[0056] Next, in the motor operation determination step, the position of a rack is calculated based on the steering angle information (S310). Subsequently, the transceiver 210 receives a signal indicating whether a variable rack and pinion system (VRS), used in the case of tire chains being installed on the vehicle wheels or when using wide tires, is operational, and a rack and pinion range modified by the variable rack and pinion system (VRS) is detected (S330). Once the rack and pinion range is determined, a threshold range of a target steering angle is established to limit the auxiliary steering force.

[0057] If the rack and pinion stroke range is fixed according to the mechanical design, a predetermined value can be stored and subsequently applied when the rack and pinion stroke range is detected. If the rack and pinion stroke range changes in real time, the variable stroke range can be updated in real time.

[0058] Subsequently, in the motor operation determination step, it is determined whether the steering angle is within the threshold range of the target angle for the rack travel range or not (S340), and if the steering angle is within the threshold range, a control is performed such that a rack stop termination function is executed to limit the rack travel range (S350), and the motor limiting mode is initiated (S360).

[0059] In the motor control signal generation step, a control signal is generated to initiate the motor limiting mode and is sent via the transceiver 210 to the variable rack and pinion (VRS) system and the electric power steering motor, thus enabling the limitation of the rack and pinion stroke.

[0060] Fig. Figure 4 is a flowchart that illustrates a method for controlling an electric power steering motor to terminate a motor limiting mode according to an embodiment of the present disclosure.

[0061] According to the above-described method for controlling the electric power steering motor, it is possible, when a small amount of auxiliary steering force is applied in the case where the frictional force of the road surface is low, or in the case where the coefficient of friction between the vehicle and the road surface is drastically reduced when the vehicle begins to move into the parking position, to effectively prevent the impact of the stopper by providing an influence on the steering wheel operation of the vehicle driver.

[0062] With reference to Fig. 4. A motor limiting mode is initiated for the electric power steering motor (S400), and information about a steering angle and information about an electric power steering motor is received in a transmit / receive step (S410), whereby at least one of a motor torque signal generated by a motor torque sensor and a motor speed signal generated by a motor position sensor provided in the electric power steering motor can be received.

[0063] In the engine operation determination step, it is then determined whether the direction of a steering angle signal of the vehicle matches the direction of a driver torque signal or not (S420).

[0064] If the direction of the torque signal matches the direction of the steering angle signal, an angular velocity of the electric power steering motor is calculated from the motor speed signal (S430).

[0065] It is then determined whether the direction of the calculated angular velocity is opposite to the direction of the torque signal or the direction of the steering angle signal (i.e., the direction of the calculated angular velocity does not match the direction of the torque signal or the direction of the steering angle signal) or not (S440), and if the direction of the calculated angular velocity is opposite to the direction of the torque signal or the direction of the steering angle signal, a control is performed to terminate the engine limiting mode (S450).

[0066] For example, it can be assumed that clockwise rotation is positive and counterclockwise rotation is negative. If a steering angle signal has a positive direction (clockwise), a torque signal has a positive direction, and the angular velocity of the electric power steering motor has a negative direction, this means that the vehicle's steering angle is outside the threshold range of the target angle and within a normal range where limiting the rack travel is unnecessary. The motor limiting mode must therefore be deactivated.

[0067] Similarly, if a steering angle signal has a negative direction (counterclockwise), a torque signal has a negative direction, and the angular velocity of the electric power steering motor has a positive direction, this means that the vehicle's steering angle is outside the threshold range of the target angle and returns to the normal range. The motor limiting mode must therefore be deactivated.

[0068] In the motor control signal generation step, a control signal to end the motor limiting mode is generated and sent via the transceiver 210 to the variable rack and pinion (VRS) system and the electric power steering motor, thus enabling the limitation of the rack and pinion stroke.

[0069] According to the above-described method for controlling the electric power steering motor, a direction can be calculated using information obtained by detecting the vehicle's steering angle and the operation of the electric power steering motor, and the operation of the electric power steering motor, which is fixed due to the rack stroke limitation, can be repeated, thereby automatically initiating or ending the motor limiting mode.

[0070] Fig. 5A and Fig. 5B diagrams are shown, which represent a method for initiating an engine limiting mode according to an embodiment of the present disclosure.

[0071] The motor limiting mode refers to a mode in which the rotation of the motor is stopped.

[0072] For example, the motor limiting mode may refer to a mode for performing an operation of switching off three-phase switches of a three-phase motor of an electric power steering system.

[0073] As another example, the motor limiting mode can refer to a mode for performing an operation to fix an electrical angle of the electric power steering motor.

[0074] It is assumed here that the electric power steering motor is an alternating current motor.

[0075] Specifically, when a current is applied to a three-phase electric power steering motor, it is driven by three waveforms (i.e., waveforms 'u', 'v', and 'w') that have a phase difference of 120 (2n / 3) degrees according to an electrical angle of the rotor. When a calculated current is applied to the electric power steering motor at a rotor angle, the rotor of the electric power steering motor is rotated according to the magnitude and direction of the angle. That is, when a current corresponding to the electrical angle according to the calculated power steering force is applied to the electric power steering motor, the rotor is rotated by that electrical angle, thereby driving the electric power steering motor.

[0076] Fig. Figure 5A shows a cross-section of a rotor of a three-phase and two-pole electric power steering motor and a current-to-electric angle diagram of it to explain the operation of fixing an electric angle of the electric power steering motor.

[0077] As in Fig. Figure 5A shows ±u, ±v, and ±w as the ends and beginnings of windings of a three-phase, two-pole electric power steering motor. Since the polarity of the magnetic field changes when the direction of the current changes, 'u', 'v', and 'w' also change, causing the motor to rotate.

[0078] As described above, the position of the electric power steering motor can be detected every 120 degrees, and changes in the waveforms 'u', 'v', and 'w' are determined by the electric angle of the electric power steering motor. When the electric angle is fixed, a certain value of the current applied to the electric power steering motor is also fixed, thus locking the motor. Therefore, when the electric angle of the electric power steering motor is fixed, the electric power steering motor can be stopped.

[0079] More precisely, the motor limiting mode via the fixing of an electrical angle refers to a mode in which the motor is stopped by performing an operation of converting alternating currents, which are applied to the respective three-phase terminals of the electric power steering motor, into direct currents.

[0080] In this case, a DC value can be determined based on the time at which the motor limiting mode is initiated and a torque signal from the driver. For example, the DC value can be determined as a value obtained by applying a weighting factor set proportional to the driver torque signal, based on the AC current values ​​applied to the respective three-phase terminals at the time the motor limiting mode is initiated.

[0081] With reference to Fig. 5A, in the event that the electrical angle of the alternating currents applied to the three-phase terminals corresponds to position 'A' at the time when the initiation of the motor limiting mode is determined, in order to fix the electrical angle of the electric power steering motor to the angle of position 'A', current values ​​corresponding to the electrical angle of position 'A' (i.e., the current values ​​corresponding to three points on the waveforms of the current-to-electric-angle graph) are set as DC values ​​and the DC currents are applied to the electric power steering motor without changing their phases, thereby fixing the rotor of the electric power steering motor and stopping its operation.

[0082] Alternatively, if the electrical angle of the alternating currents applied to the three-phase terminals corresponds to position 'A' at the time the motor limiting mode is initiated, direct currents can be determined by multiplying the values ​​of the currents applied to the respective three-phase terminals at position 'A' by a weighting factor proportional to the driver's steering torque, and then applying these values ​​to the respective three-phase terminals. Thus, since the current values ​​applied to the motor's three-phase terminals increase with increasing driver steering torque, it is possible to lock the rotor with a greater force. Conversely, if the driver's steering torque decreases, the current values ​​applied to the motor's three-phase terminals decrease proportionally, allowing the rotor to be locked with a weaker force.This can result in the suppression of excess heat generated by the motor and can fix the motor's rotation solely using the current dynamically required according to the driver's steering torque, thus providing benefits in terms of heat generation and energy waste.

[0083] The predetermined weighting factor can be pre-stored as a value corresponding to a driver torque value or range thereof, through a test or similar procedure.

[0084] Simultaneously, if the driver turns the steering wheel in the direction where the rack stop impacts, and thereby gradually increases a force in the state where the electric angle is fixed by prior setting of current values ​​according to position 'A' as DC values ​​(i.e., if the driver torque is increased by turning the steering wheel with a strong force within a range of the steering angle in which the rack travel is limited), a torque value from the steering torque sensor can be calculated, and a value of the current applied to the electric power steering motor can be increased proportionally, thus maintaining the motor limiting mode.

[0085] On the other hand, if the driver turns the steering wheel in the direction where the rack stop impacts, gradually reducing the force applied, the current supplied to the electric power steering motor can be reduced, thus maintaining the motor limiting mode.

[0086] This can reduce the heat generation of the electric power steering motor and the heterogeneity for a change in the assist steering force due to the motor limiting mode when the vehicle driver turns the steering wheel, while effectively reducing the amount of assist steering force required by the vehicle driver.

[0087] Fig. 5B is a circuit diagram of an electric power steering motor to describe an operation of switching off three-phase switches of the electric power steering motor.

[0088] More precisely, switches S1 to S6 of a three-phase electric power steering motor are switched on and off to apply alternating current to three-phase terminals 'u', 'v', and 'w'. Changing the sequence of the switches' on / off operations also changes the sequence of uv, vw, and wu, thereby changing the direction of rotation of the electric power steering motor. Preferably, a semiconductor device in the form of an insulated-gate bipolar transistor (IGBT) can be used as the switching device; however, the present disclosure is not limited to this.

[0089] As in Fig. As shown in Figure 5B, the electric power steering motor can be inhibited by switching off (opening) the switches for the three-phase terminals 'u', 'v' and 'w' so that it stops regardless of the external force.

[0090] It is therefore possible to initiate the motor limiting mode, in which the operation of the electric power steering motor is stopped, using the procedure described above.

[0091] As described above, according to a device and a method for controlling a motor of an electric power steering system as disclosed above, it is possible to reduce damage to the vehicle, provide a benefit to the driver, minimize heterogeneity due to a sudden change in the steering of the vehicle, and stably control the movement of the vehicle in a situation where an external force is exerted on the vehicle by effectively limiting the rack stroke.

Claims

[1] Device for controlling a motor (130) of an electric power steering system, the device comprising: a transceiver (210) designed to receive information about a steering angle and information about the motor (130) of the electric power steering and to send a control signal to the motor (130) of the electric power steering; a motor operation determination device (221) designed to detect a rack and pinion stroke range and, based on the received information about the steering angle and the electric power steering motor (130), to determine whether a motor limiting mode needs to be initiated or terminated; and a motor control signal generator (222) designed to generate a control signal according to the specified initiation or termination of the motor limiting mode, characterized by , that The motor operation determination device (221) is designed to calculate a position of the rack (109) based on information about the steering angle, and is designed to calculate the strength of a current supplied to the electric power steering motor (130) and an angular velocity of the electric power steering motor (130) based on information about the electric power steering motor (130). [2] Device according to claim 1, wherein the transmitter receiver (210) is designed to receive at least one torque signal generated by a torque sensor (121) and a steering angle signal generated by a steering angle sensor when receiving information about the steering angle, and is designed to receive an engine speed signal generated by an engine position sensor when receiving information about the motor (130) of the electric power steering. [3] Device according to claim 1, wherein the motor operation control device (221) is designed to perform control so that the motor limiting mode is initiated when the steering angle is within a threshold range of a target angle for the rack and pinion stroke range. [4] Device according to claim 1, wherein the motor limiting mode is a mode for stopping the rotation of the motor (130) of the electric power steering and a mode for performing an operation of switching off three-phase switches of the motor (130) of the electric power steering. [5] Device according to claim 2, wherein the motor operation determination device (221) is designed to determine the direction of the steering angle signal and the direction of the torque signal and is designed to calculate the angular velocity of the motor (130) of the electric power steering using the motor speed signal. [6] Device according to claim 5, wherein the motor operation control device (221) is designed to perform control so that the motor limiting mode is terminated when the direction of the steering angle signal matches the direction of the torque signal and when the direction of the calculated angular velocity of the motor (130) of the electric power steering does not match the direction of the steering angle signal in the motor limiting mode. [7] Device according to claim 1, wherein the motor limiting mode is a mode for stopping the rotation of the motor (130) of the electric power steering and a mode for converting the alternating currents applied to the respective three-phase terminals of the motor of the electric power steering into direct current values. [8] Device according to claim 7, wherein the DC current values ​​are determined based on the time at which the initiation of the motor limiting mode is determined and a torque signal from a driver. [9] Device according to claim 8, wherein the DC current values ​​are determined by applying a weighting factor set proportional to the torque signal, based on alternating current values ​​applied to the respective three-phase terminals of the electric power steering motor (130) at the time when the initiation of the motor limiting mode is determined. [10] Method for controlling a motor (130) of an electric power steering system, the method comprising: a transmit / receive step of receiving information about a steering angle and information about the motor (130) of the electric power steering and sending a control signal to the motor (130) of the electric power steering; a motor operation determination step of detecting a rack and pinion stroke range and determining, based on the received information about the steering angle and the electric power steering motor (130), whether a motor limiting mode needs to be initiated or terminated, and a motor control signal generation step of generating a control signal according to the specific initiation or termination of the motor limiting mode; characterized by , that a position of the rack (109) is calculated based on the information about the steering angle, and the strength of a current supplied to the motor (130) of the electric power steering, and an angular velocity of the motor (130) of the electric power steering are calculated based on the information about the motor (130) of the electric power steering. [11] Method according to claim 10, wherein the transmit / receive step comprises: Receiving, when receiving the steering angle information, from at least one torque signal generated by a torque sensor (121) and a steering angle signal generated by a steering angle sensor; and Receiving, when receiving information about the motor (130) of the electric power steering, from a motor speed signal generated by a motor position sensor. [12] Method according to claim 11, wherein the motor operation determination step comprises: Determining the direction of the steering angle signal and the direction of the torque signal; and Calculating the angular velocity of the motor (130) of the electric power steering using the motor speed signal. [13] Method according to claim 12, wherein the motor operation determination step comprises performing a control operation to terminate the motor limiting mode when the direction of the steering angle signal matches the direction of the torque signal and when the direction of the calculated angular velocity of the motor (130) of the electric power steering does not match the direction of the steering angle signal in the motor limiting mode. [14] Method according to claim 10, wherein the motor limiting mode is a mode for stopping the rotation of the motor (130) of the electric power steering and is a mode for performing an operation of switching off three-phase switches of the motor (130) of the electric power steering or an operation of converting alternating currents applied to respective three-phase terminals of the motor (130) of the electric power steering into direct current values. [15] Method according to claim 14, wherein the DC current values ​​are determined based on the time at which the initiation of the motor limiting mode is determined and a torque signal from a driver. [16] Method according to claim 15, wherein the DC current values ​​are determined by applying a weighting factor set proportional to the torque signal, based on values ​​of alternating currents applied to the respective three-phase terminals of the motor (130) of the electric power steering at the time when the initiation of the motor limiting mode is determined.

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