MOTOR-DRIVEN POWER STEERING SYSTEM WITH REDUNDANCY STRUCTURE

Description

BACKGROUND FIELD

[0001] Embodiments of the present disclosure relate to a motor driven power steering system of a redundancy structure, and more particularly, to a motor driven power steering system of a redundancy structure in which a driving motor for redundant driving of the motor driven power steering system is independently controlled through a redundant circuit.DISCUSSION OF THE BACKGROUND

[0002] In general, a motor driven power steering system (MDPS) may provide auxiliary torque in a direction in which a driver of a vehicle steers a wheel by using an electric motor, thereby making the driver's wheel handling lighter.

[0003] Unlike a conventional hydraulic power steering (HPS) system, the motor driven power steering system may have improved steering performance and steering feel by automatically controlling an operation of the electric motor based on a driving condition of the vehicle.

[0004] Here, the motor driven power steering system may determine the driving condition of the vehicle by including a torque sensor that measures the driver's steering torque input to the steering wheel, a steering angle sensor that measures a steering angle of the steering wheel, and a vehicle speed sensor that measures a vehicle speed.

[0005] As such, the motor driven power steering system may be a major system that greatly affects steering safety of the vehicle, and reliable and safe driving of the motor driven power steering system may be an essential element for a safe operation of the vehicle.

[0006] A driving motor used in the motor driven power steering system may include a direct current (DC) motor or an alternating current (AC) motor. In case of a conventional three-phase brushless AC motor, a study on a double winding motor to which double winding is applied is being actively conducted for a more reliable operation of the driving motor.

[0007] The double winding motor may include two or more power supplies, and may be a motor designed to drive the motor only by inputting power to the remaining power supply even if a motor element or motor winding connected to any one of the two or more power supplies fails or breaks.

[0008] Meanwhile, the double winding motor may implement a redundancy structure of the motor, thereby improving the safe and reliable driving of the motor.

[0009] Therefore, there has been a need to improve the safe and reliable driving of the motor through the redundancy structure by applying such a double winding structure even to the driving motor used in the motor driven power steering system.

[0010] Background technology of the present disclosure is disclosed in Korea Patent Laid-Open Publication No. 10-2020-0091651 (published on July 31, 2020, and entitled "REDUNDANCY CIRCUIT FOR ELECTRIC POWER STEERING SYSTEM").

[0011] US 2020 / 353975 A1 discloses an ECU including a plurality of control circuits which is configured to control driving of a motor and communicate each other. In the document it is described that the control circuits are configured to switch control modes including an ADS mode for controlling the driving of the motor based on a steering angle command θs* and a torque control mode for controlling the driving of the motor based on a torque command value, a first control circuit, which calculates an EPS current command value shared by the plurality of control circuits in an EPS mode, and a second control circuit, which calculates an ADS current command value shared by the plurality of control units in an ADS mode, are different.

[0012] EP 3 466 795 A1 discloses an electronic control device which includes at least two pairs of detection means and in which determination as to abnormality of the detection means is performed and, when an abnormality is detected, switching to a normal one of the pairs is performed and control is continued, the device allowing a time period taken until switching to the normal pair to be shortened and allowing reduction in load for a control process, an abnormality determination means performing detection of abnormality of one of the pairs of detection means at a normal speed, and performing detection of abnormality of the other of the pairs at a speed not higher than the normal speed, and, when a sign of abnormality of the detection means being detected at the normal speed, a CPU performing switching to the other normal pair and continues control, and the abnormality determination means performing detection of abnormality of the other normal pair at the normal speed, and meanwhile, continues to perform detection of abnormality of the abnormal pair at a speed not higher than the normal speed.SUMMARY

[0013] A motor driven power steering system may drive various actuators centered on an electronic control device, and thus require an independent redundancy structure as a demand for its safety and reliability further increases due to arrival of an autonomous driving era.

[0014] The invention is set out in the appended set of claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a block diagram showing a motor driven power steering system of a redundancy structure according to an embodiment of the present disclosure. FIG. 2 is an exemplary diagram briefly showing arrangement of a position sensor in the motor driven power steering system of a redundancy structure according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0016] As is traditional in the corresponding field, some exemplary embodiments may be illustrated in the drawings in terms of functional blocks, units, and / or modules. Those of ordinary skill in the art will appreciate that these block, units, and / or modules are physically implemented by electronic (or optical) circuits such as logic circuits, discrete components, processors, hard-wired circuits, memory elements, wiring connections, and the like. When the blocks, units, and / or modules are implemented by processors or similar hardware, they may be programmed and controlled using software (e.g., code) to perform various functions discussed herein. Alternatively, each block, unit, and / or module may be implemented by dedicated hardware or as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed processors and associated circuitry) to perform other functions. Each block, unit, and / or module of some exemplary embodiments may be physically separated into two or more interacting and discrete blocks, units, and / or modules without departing from the scope of the inventive concept. Further, blocks, units, and / or module of some exemplary embodiments may be physically combined into more complex blocks, units, and / or modules without departing from the scope of the inventive concept.

[0017] The embodiments described in this specification may be implemented with a method or process, a device, a software program, a data stream or a signal, for example. Although a feature is discussed only in a single context (for example, discussed only in a method), the discussed feature can be implemented in another type (for example, apparatus or program). An apparatus may be implemented in suitable hardware, software or firmware. The method can be implemented in a device such as a processor which generally refers to a processing device including a computer, a microprocessor, an integrated circuit or a programmable logic device. The processor also includes a communication device, such as a computer, cellular phone, PDA (Personal Digital Assistant) and another device, which facilitates information communication between end users. Hereinafter, a motor driven power steering system of a redundancy structure will be described below with reference to the accompanying drawings through various embodiments.

[0018] FIG. 1 is a block diagram showing a motor driven power steering system of a redundancy structure according to an embodiment of the present disclosure; and FIG. 2 is an exemplary diagram briefly showing arrangement of a position sensor in the motor driven power steering system of a redundancy structure according to an embodiment of the present disclosure.

[0019] As shown in FIG. 1, the motor driven power steering system of a redundancy structure according to an embodiment of the present disclosure includes a driving motor 50, first and second power circuits 11 and 12, and first and second driving circuits 31 and 32, first and second position sensors 41 and 42, and first and second processors 21 and 22.

[0020] The driving motor 50 is be a driving actuator of the motor driven power steering system, and substantially rotate and steer a steering wheel (not shown).

[0021] Here, the driving motor 50 may be a double winding motor that outputs one power but includes a first winding motor 51 and a second winding motor 52 therein, and have a redundancy structure in which the driving motor 50 is driven through control means independent from each other.

[0022] Accordingly, the first winding motor 51 may be operatively coupled to the first power circuit 11, the first position sensor 41, the first driving circuit 31, and the first processor 21; and the second winding motor 52 may be operatively coupled to the second power circuit 12, the second position sensor 42, the second driving circuit 32, and the second processor 22.

[0023] The first and second power circuits 11 and 12 may respectively supply control power and driving power to the first and second processors 21 and 22 and the first and second driving circuits 31 and 32, independently from each other.

[0024] The first and second driving circuits 31 and 32 may respectively vary a frequency of the three-phase power supply based on control signals of the first and second processors 21 and 22 to adjust the speed and torque of the first winding motor 51 and the second winding motor 52 of the driving motor 50, thereby independently driving the driving motor 50.

[0025] Here, the first and second driving circuits 31 and 32 may each include at least one phase switch, including an inverter, which converts direct current (DC) driving power to the three-phase power supply, and at least one cut-off switch completely which cuts off the three-phase power supply when a failure occurs therein.

[0026] In this case, the phase switch and the cut-off switch may be a power semiconductor device such as a metal-oxide-semiconductor field-effect transistor (MOSFET) / insulated gate bipolar transistor (IGBT).

[0027] The first and second position sensors 41 and 42 each detect a rotational position of the driving motor 50 to output a position signal and a comparison signal, thereby comparing and verifying whether a measured value is normal.

[0028] Here, the first and second position sensors 41 and 42 may be respectively mounted on positions corresponding to those of the lower surface and upper surface of one circuit board 60 as shown in FIG. 2.

[0029] Here, the first position sensor 41, the circuit board 60, and the second position sensor 42 may be sequentially arranged in a magnetic flux direction (i.e., z-axis direction) of a position detection magnet 55 positioned in the driving motor 50, and the first position sensor 41 and the second position sensor 42 may thus be robust against an external magnetic field.

[0030] Accordingly, the first position sensor 41 transmits to the first processor 21, each of a first position signal for detecting position of the magnet 55 and a first comparison signal for monitoring and comparing whether the first position signal is normal; and the second position sensor 42 transmits to the second processor 22, each of a second position signal for detecting the position of the magnet 55 and a second comparison signal for monitoring and comparing whether the second position signal is normal.

[0031] The first and second processors 21 and 22 are operatively coupled to the driving motor 50, the first and second power circuits 11 and 12, the first and second position sensors 41 and 42, and the first and second driving circuits 31 and 32, respectively.

[0032] Accordingly, the first processor 21 receives a steering control signal from an upper-level control device to allow the first driving circuit 31 to be operated based on the first position sensor 41, thereby allowing the first winding motor 51 of the driving motor 50 to be operated.

[0033] In addition, the second processor 22 receives a steering control signal from the upper control device independently from the first processor 21 to allow the second driving circuit 32 to be operated based on the second position sensor 42, thereby allowing the second winding motor 52 of the driving motor 50 to be operated.

[0034] Here, the first processor 21 stops its operation when a tolerance between the first position signal and the first comparison signal is out of a predetermined first reference error as a result of the comparison of the two signals; and the second processor 22 stops its operation when a tolerance between the second position signal and the second comparison signal is out of a predetermined second reference error as a result of the comparison of the two signals. Accordingly, any one processor may allow the driving motor 50 to be operated to enable the steering unless the error occurs in both the first position sensor 41 and the second position sensor 42. The first reference error and the second reference error may be the same or different from each other based on a system environment.

[0035] Meanwhile, one processor takes a main control and allows the driving motor 50 to be operated while the first and second processors 21 and 22 monitor their mutual operation states, and the main control is switched to the other processor when the error occurs, and the other processor is driven to allow the driving motor 50 to be operated.

[0036] As described above, according to the motor driven power steering system of a redundancy structure according to an embodiment of the present disclosure, the position sensor, driving circuit, processor, and power supply of the driving motor for redundant driving of the motor driven power steering system may each have the redundancy structure to be driven independently from each other, and the driving motor may thus be allowed to be operated by the other independent processor even when one processor fails, thereby securing stability of the processor and robustness of the position sensor against the external magnetic field.

[0037] The implementation described herein may be implemented in, for example, a method or process, an apparatus, a software program, a data stream, or a signal. Although implementation is disclosed only in a single form (e.g., only as a method), the implementation of the disclosed feature may also be implemented in another form (e.g., as an apparatus or program). The apparatus may be implemented in suitable hardware, software, firmware, or the like. For example, the method may be implemented in the apparatus such as a processor which generally refers to a computer, a micro-processor, a processing device including an integrated circuit, a programmable logic device or the like, etc. The processor may also include a communication device such as a computer, a mobile phone, a portable / personal digital assistant ("PDA") or another device, which facilitates communications of information between end-users.

[0038] As set forth above, according to the motor driven power steering system of a redundancy structure according to the embodiments of the present disclosure, the position sensor, driving circuit, processor, and power supply of the driving motor for the redundant driving of the motor driven power steering system may each have the redundancy structure to be driven independently from each other, and the driving motor may thus be allowed to be operated by the other independent processor even when one processor fails, thereby securing the stability of the processor and the robustness of the position sensor against the external magnetic field.

Claims

1. A motor driven power steering system of a redundancy structure, the system comprising: a driving motor (50) configured to drive a steering wheel; first and second driving circuits (31, 32) configured to drive the driving motor (50); first and second position sensors (41, 42) configured to detect a rotational position of the driving motor (50); and first and second processors (21, 22), wherein the first processor (21) is configured to receive a steering control signal from an upper-level control device to allow the first driving circuit (31) to be operated based on the first position sensor (41), thereby allowing the driving motor (50) to be operated, and the second processor (22) is configured to receive a steering control signal from the upper-level control device to allow the second driving circuit (32) to be operated based on the second position sensor (42), thereby allowing the driving motor (50) to be operated, wherein the first position sensor (41) is configured to transmit each of a first position signal and a first comparison signal to the first processor (21), and the second position sensor (42) is configured to transmit each of a second position signal and a second comparison signal to the second processor (22), wherein the first processor (21) is configured to stop its operation when a tolerance between the first position signal and the first comparison signal is out of a predetermined first reference error as a result of comparison of the two signals, and the second processor (22) is configured to stop its operation when a tolerance between the second position signal and the second comparison signal is out of a predetermined second reference error as a result of comparison of the two signals, and wherein the first and second processors (21, 22) are configured to monitor their mutual operation states, one processor is configured to take a main control and allow the driving motor (50) to be operated while the first and second processors (21, 22) monitor their mutual operation states, and the main control is switched to the other processor when the error occurs, and the other processor is configured to allow the driving motor (50) to be operated.

2. The system of claim 1, wherein the first position sensor (41) and the second position sensor (42) are respectively mounted on positions corresponding to those of the lower surface and upper surface of one circuit board.

3. The system of claim 2, wherein the first position sensor (41), the circuit board, and the second position sensor (42) are sequentially arranged in one magnetic flux direction of a position detection magnet positioned in the driving motor (50).

4. The system of claim 1, further comprising: first and second power circuits (11, 12) configured to supply control power, wherein the first and second processors (21, 22) are operatively coupled to the driving motor (50), the first and second power circuits (11, 12), the first and second position sensors (41, 42), and the first and second driving circuits (31, 32), respectively.

5. The system of any one of claims 1 to 4, wherein the driving motor (50) is a double winding motor including a first winding motor (51) and a second winding motor (52).

6. The system of claim 5, wherein the first winding motor (51) is operatively coupled to the first power circuit (11), the first position sensor (41), the first driving circuit (31), and the first processor (21), and the second winding motor (52) is operatively coupled to the second power circuit (12), the second position sensor (42), the second driving circuit (32), and the second processor (22).

7. The system of any one of claims 1 to 6, wherein the first and second driving circuits (31, 32) each include at least one phase switch configured to convert direct current (DC) driving power to a three-phase power supply, and at least one cut-off switch configured to completely cut off the three-phase power supply when a failure occurs therein.

8. The system of claim 7, wherein: the first winding motor (51) is operatively coupled to the first position sensor (41), the first driving circuit (31), and the first processor (21), and the second winding motor (52) is operatively coupled to the second position sensor (42), the second driving circuit (32), and the second processor (22).