JP2004080939A - Steering device with redundancy system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device having a redundancy system, in which the assist of a manual steering force is not interrupted, even if a trouble occurs in an electronic drive control system or the like of a motor control device, and which prevents system down from occurring and having a redanduncy system that allows continuous system operation. <P>SOLUTION: The steering device comprises a torque detection part 20 that detects steering torque; a target current determining part 31 that determines motor current according to the steering torque outputted from the torque detecting part; a drive circuit part (arranged in a control device 22) that feeds a current to a motor 19, according to the motor current determined by the target current determining part. The drive circuit part has two-passage and identical motor drive circuits 44a, 44b. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a steering device having a redundant system, and more particularly to a steering device such as an electric power steering device or the like in which an electronic drive control system for operating a motor is duplicated to increase system resistance against failure of the system and improve system reliability. .
[0002]
[Prior art]
Examples of the steering device include an electric power steering device and a steer-by-wire system. BACKGROUND ART An electric power steering device as an example of a steering device is a support device that assists a steering force by linking a motor when a driver operates a steering wheel (steering handle) while driving an automobile. The electric power steering device uses a steering torque signal from a steering torque detection unit that detects a steering torque generated on a steering shaft by a driver's steering operation, and a vehicle speed signal from a vehicle speed detection unit that detects a vehicle speed. Based on the control operation of a control device (ECU (Electrical Control Unit): electronic control unit), the driving of the assisting motor that outputs the assisting steering force is controlled to reduce the manual steering force of the driver. In the control operation by the motor control device, a target current value of a motor current to be supplied to the motor is set based on the steering torque signal and the vehicle speed signal, and a signal (a target current signal) relating to the target current value is actually transmitted to the motor. A difference from a motor current signal fed back from a motor current detection unit for detecting a flowing motor current is obtained, and a proportional / integral compensation process (PI control) is performed on the difference signal to generate a signal for driving control of the motor. Let me.
[0003]
The assisting motor driven by the ECU transmits the rotation output to a gear box including a rack and pinion mechanism connected to the steering shaft via a power transmission mechanism (reduction gear). Thus, the steering force of the driver operating the steering wheel is assisted.
[0004]
As described above, in the electric power steering apparatus, an electronic drive control system including a sensor system such as a steering torque detection unit, an ECU including a CPU and a drive circuit system, and a current supply system for supplying a motor current from the ECU to a support motor. It has.
[0005]
[Problems to be solved by the invention]
In a conventional electric power steering device, when a failure occurs in an electronic drive control system for driving a motor provided in an ECU and related parts, a warning light is displayed on a driver's seat display panel or the like based on fail-safe control. Is turned on, and when the steering force assist control cannot be performed completely, the steering system is returned to the configuration of the steering system by a normal manual operation.
[0006]
In recent years, it has been desired that the operation state of the electric power steering device is continuously maintained even when the above-described failure occurs, and the driver can assist the driver with the manual steering force.
[0007]
Although the example of the electric power steering device has been described above, the above-described problem is a problem generally required for a steering device that drives and controls the motor using a motor.
[0008]
In view of the above problems, an object of the present invention is to provide a steering system having a redundant system capable of continuing without interrupting manual steering force assistance even if a failure occurs in an electronic drive control system or the like of a motor control device. Is to provide.
[0009]
Means and action for solving the problem
A steering device having a redundant system according to the present invention is configured as follows to achieve the above object.
[0010]
The first steering device (corresponding to claim 1) includes: a torque detecting unit that detects a steering torque; a target current determining unit that determines a motor current according to the steering torque output from the torque detecting unit; A steering device including a drive circuit unit that supplies a current to a motor in accordance with a motor current determined by a current determination unit, the drive circuit unit including two identical drive circuits (motor drive circuits).
[0011]
In the steering device described above, the drive circuit for supplying the motor current to the motor is provided in two paths. Therefore, even if one of the drive circuits fails, the remaining drive circuit can supply the motor current and the system can be shut down. It is possible to prevent the situation, maintain the system, and maintain high system reliability.
[0012]
In the second steering device (corresponding to claim 2), in the above-described first configuration, preferably, the motor is a brushed motor having at least two brush pairs, and the two-path drive circuit is at least two sets. Is configured to be connected to each of the brush pairs. In this configuration, two sets of brush pairs of a motor with a brush are provided, and a connection relationship is created so as to correspond to each of the two-path drive circuits.
[0013]
In the third steering device (corresponding to claim 3), in the first configuration, preferably, the motor is a brushless motor, and the brushless motor has two coils (windings) forming separate electric circuits. The heavily wound, two-path drive circuit is characterized by separately supplying current to each of the coils forming a separate electrical circuit. In this configuration, two sets of stator windings of the brushless motor are provided, and a connection relationship is made to correspond to each of the two-path drive circuits.
[0014]
The fourth steering device (corresponding to claim 4) in the above-described first configuration, preferably, has one motor, and two paths of drive circuits are provided in parallel with this one motor, The motors are configured to be driven in parallel by a two-path drive circuit.
[0015]
In the fifth steering device (corresponding to claim 5), in the above-described first configuration, preferably, two target current determination units are provided, and transmission of a detection signal from the torque detection unit is divided into two paths. Is supplied to each of the two target current determination units.
[0016]
A sixth steering device (corresponding to claim 6) is preferably characterized in that, in the first configuration, a connection relationship between the drive circuit unit and a power supply that supplies a motor current is formed in two paths. Attached.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[0018]
Configurations, shapes, sizes, and arrangements described in the embodiments are merely schematically illustrated to the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the embodiments described below, and can be modified in various forms without departing from the scope of the technical idea described in the claims.
[0019]
In this embodiment, an example of an electric power steering device will be described as an example of a steering device.
[0020]
An overall configuration of a basic electric power steering device will be described with reference to FIG. The electric power steering device 10 is mounted on, for example, a passenger vehicle. The electric power steering device 10 is configured to apply auxiliary steering torque to a steering shaft 12 and the like connected to a steering wheel 11. An upper end of the steering shaft 12 is connected to the steering wheel 11, and a pinion gear 13 is attached to a lower end. The lower portion of the steering shaft 12 is called a pinion shaft and is connected to the upper portion by a universal joint, but is not shown in FIG. A rack shaft 14 provided with a rack gear 14a that meshes with the pinion gear 13 is disposed. A rack and pinion mechanism 15 is formed by the pinion gear 13 and the rack gear 14a. Tie rods 16 are provided at both ends of the rack shaft 14, and a front wheel 17 is attached to an outer end of each tie rod 16. A motor 19 such as a brush motor or a brushless motor is provided to the steering shaft 12 via a power transmission mechanism (reduction gear) 18. The motor 19 outputs a rotational force (torque) for assisting the steering torque, and applies the rotational force to the steering shaft 12 via the power transmission mechanism 18.
[0021]
The steering shaft 12 is provided with a steering torque detector 20. The steering torque detection unit 20 detects the steering torque applied to the steering shaft 12 when the steering torque generated by operating the steering wheel 11 by the driver is applied to the steering shaft 12, for example. Reference numeral 21 denotes a vehicle speed detection unit that detects the vehicle speed of the vehicle, and reference numeral 22 denotes a control device (ECU) including a computer (microcomputer or the like). The control device 22 takes in the steering torque signal T output from the steering torque detection unit 20 and the vehicle speed signal V output from the vehicle speed detection unit 21 and controls the motor 19 based on the information on the steering torque and the information on the vehicle speed. A drive control signal SG1 for controlling the rotation operation is output. Further, the motor 19 is provided with a motor rotation angle detection unit 23. A signal SG2 related to the rotation angle (electrical angle) of the motor rotation angle detection unit 23 is input to the control device 22. The rack and pinion mechanism 15 and the like are housed in a gear box 24 not shown in FIG.
[0022]
In the above description, the electric power steering device 10 is configured by adding a steering torque detection unit 20, a vehicle speed detection unit 21, a control device 22, a motor 19, and a power transmission mechanism 18 to the device configuration of a normal steering system. .
[0023]
In the above configuration, when the driver operates the steering wheel 11 to perform steering in the traveling direction during traveling of the automobile, the rotational force based on the steering torque applied to the steering shaft 12 is transmitted via the rack and pinion mechanism 15. It is converted into the linear motion of the rack shaft 14 in the axial direction, and further attempts to change the running direction of the front wheel 17 via the tie rod 16. At this time, at the same time, the steering torque detector 20 attached to the steering shaft 12 detects the steering torque according to the steering by the driver on the steering wheel 11 and converts it into an electric steering torque signal T. The steering torque signal T is output to the control device 22. The vehicle speed detection unit 21 detects the vehicle speed of the vehicle, converts the vehicle speed into a vehicle speed signal V, and outputs the vehicle speed signal V to the control device 22. Control device 22 generates a motor current for driving motor 19 based on steering torque signal T and vehicle speed signal V. The motor 19 driven by this motor current applies an auxiliary steering torque to the steering shaft 12 via the power transmission mechanism 18. By driving the motor 19 as described above, the driver's steering force applied to the steering wheel 11 is reduced.
[0024]
The control device 22 includes a target current determining unit 31 and a control unit 32, as shown in FIG. The target current determination unit 31 determines a target auxiliary torque mainly based on the steering torque signal T, and a signal (target current signal) IT relating to a target current value required to supply the target auxiliary torque from the motor 19. Is output.
[0025]
The general configuration of the control unit 32 will be outlined. The control unit 32 includes a deviation calculation unit, a motor control unit, a motor drive unit, and a current value detection unit as functional elements or electric circuit elements realized as software. The motor controller includes a deviation current controller and a PWM signal generator. The deviation current control unit generates and outputs a drive current signal for controlling the motor current based on the current signal provided from the deviation calculation unit. The PWM signal generation unit generates a PWM (pulse width modulation) signal for performing the PWM operation of the motor 19 based on the drive current signal provided from the deviation current control unit. The motor drive section includes a gate drive circuit section and a motor drive (drive) circuit (an H-type bridge circuit formed by four FETs). The gate drive circuit causes the motor drive circuit to perform a switching operation based on the drive control signal (PWM signal). As described above, the control device 22 performs PWM control of the motor current supplied from the vehicle-mounted battery (DC power supply) to the motor 19 by the motor drive circuit based on the steering torque detected by the steering torque detection unit 20, and the motor 19 outputs Power (auxiliary steering torque) to be controlled.
[0026]
Next, a specific embodiment of the control device (ECU) 22 shown in FIG. 2 will be described with reference to FIG.
[0027]
The detection signal output terminal of the steering torque detector 20 has both terminals 20a and 20b and a center terminal 20c. Each of the two terminals 20a and 20b and two terminals of the center terminal 20c is provided. Two paths of electric connection portions 41a and 41b are provided between the both terminals 20a and 20b, the center terminal 20c, and the control device 22 of the steering torque detector 20. This electric connection part is a part including a harness and a coil connection part. On the input side of the control device 22, torque signal input portions 42a and 42b are provided corresponding to the electric connection portions 41a and 41b.
[0028]
The control device 22 includes three CPUs (1 to 3) 43a, 43b, and 43c. Each of the two torque signal input sections 42a and 42b has three output terminals, and the corresponding output terminal between the two torque signal input sections 42a and 42b outputs the same signal (SG11, SG12, SG13). I do. The same signal is input to each of the three CPUs 43a to 43c from each of the two torque signal input units 42a and 42b via two paths. The three CPUs 43a to 43c are connected two by two in an arbitrary combination, so that a majority decision can be made by the three CPUs. Therefore, for example, when a failure occurs in the electrical connection units 41a and 41b from the steering torque detection unit 20, the failure is determined by a majority determination method. The above-described various functional elements are realized in software by the CPUs 43a to 43c. Preferably, two target current determination units 31 are formed, and the two target current determination units receive the steering torque signals from the two paths, respectively, and each target current determination unit determines the target current. ing.
[0029]
On the rear side of the control device 22, two motor drive (drive) circuits (1, 2) 44a, 44b, two booster circuits (1, 2) 45a, 45b, and two F / S relays (1, 2) 2) 46a, 46b and two power relays (1, 2) 47a, 47b are provided. These two elements have the same configuration and operation. The motor drive circuit 44a has a prohibition circuit (1) 48a connected between them in correspondence with the CPU 43a, and the motor drive circuit 44b has a prohibition circuit (3) 48c connected between them in correspondence with the CPU 43c. . As a result, regarding the drive control of the motor 19, a first motor drive circuit section (first path) is formed by the CPU 43a, the inhibition circuit 48a, and the motor drive circuit 44a in the control device 22, and the CPU 43c, the inhibition circuit 48b, and the motor A second motor drive circuit section (second path) is formed by the drive circuit 44b.
[0030]
The signal output from the CPU 43b is applied to the inhibition circuit (2) 48c, and the output signal of the inhibition circuit 48c is applied to the inhibition circuit 48c. Also, the signal is output from the CPU 43a to the inhibit circuit 48b.
[0031]
The motor (M) 19 is a motor with a brush. In this motor 19, two pairs (49a, 49b) of a pair of brushes are provided. Motor current I _M1 output from the motor drive circuit 44a of the first motor drive circuit section of the (first path) is supplied to the motor 19 through the brushes 49a. Motor current I _M2 output from the motor drive circuit 44b of the second motor drive circuit portion of the (second path) is supplied to the motor 19 through the brush 49b. Therefore, two brush pairs are provided in the brush motor 10 according to the first and second motor drive circuits. In addition, an electric connection portion such as a motor harness is formed by two paths so that each of the motor currents I _M1 and I _M2 can be supplied.
[0032]
The battery 50 supplies power to the control device 22. Two paths 51a and 51b are formed as a power supply path from the battery 50. In the first power supply path 51a, the first power path is via the power relay 47a and the booster circuit 45a, the second power path is directly via the power relay 47a, and the third power path is via the power relay 47a. Thus, electric power is supplied to the motor drive circuit 44a. Similarly, in the second power supply path 51b, the power supply 47b and the booster circuit 45b serve as the first power supply path, the power supply 47b directly serves as the second power supply path, and the power relay 47b serves as the third power supply path. , Power is supplied to the motor drive circuit 44b.
[0033]
Motor current _{I M1} outputted from the motor drive circuit 44a is detected by the current sensor 52a, is fed back to the respective CPU43a～43c. The motor current _{I M2} outputted from the motor drive circuit 44b is detected by the current sensor 52 b, it is fed back to the respective CPU43a～43c.
[0034]
In the configuration of the control device 22 according to the first embodiment described above, the electrical connection from the steering torque detection unit 20 to the control device 22, the motor drive circuit unit including the motor drive circuits 44a and 44b, and the battery 50 to the motor drive circuit 44a , 44b, and the brush pair (49a, 49b) of the motor 19 are divided into two paths (duplex) based on a parallel connection relationship. The electric power steering device can be operated on the route of (1), and by providing the redundant system, the system down of the electric power steering device can be prevented.
[0035]
Usually, one of the two-path motor drive circuits 44a and 44b provided in a parallel connection relationship performs motor drive control so that one of them is in an operating state, and operates the other motor drive circuit when a failure occurs. . Further, the motor drive circuits 44a and 44b of two paths may be operated at the same time to perform the motor drive control in both, and when a failure occurs, the motor drive control may be performed in the remaining motor drive circuits. The above-described inhibition circuits 48a, 48b, and 48c are means for selecting a circuit system used for motor drive control inside the control device 22.
[0036]
In the above-described embodiment, the system configuration of the electric power steering apparatus is provided with redundancy by a double configuration. However, the present invention is not limited to this, and it is needless to say that the configuration can be three or more.
[0037]
Next, a specific configuration of the control device 22 according to the second embodiment of the present invention will be described with reference to FIG. 4, elements substantially the same as the elements described in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. As a characteristic configuration according to the second embodiment, the motor 19 is a brushless motor. The illustrated brushless motor 19 has three-phase windings 19x, 19y, and 19z as stator coils. In the illustrated example, the windings 19x, 19y, and 19z are configured as Y connections.
[0038]
With respect to the brushless motor 19, the motor drive circuits 44a and 44b in the control device 22 are configured as three-phase AC generation circuits. Therefore, the motor drive circuits 44a and 44b have three output terminals for three-phase AC output. The windings (19x, 19y), (19y, 19z), (19y, 19z), and the like in the brushless motor 19 are based on any two combinations of the three output terminals of the motor drive circuit 44a that is the first motor drive circuit section (first path). The motor current is supplied to the energization route of (19z, 19x). Similarly, based on arbitrary two combinations of three output terminals of the motor drive circuit 44b, which is a second motor drive circuit (second path), the windings (19x, 19y), (19y, Motor current is supplied to the energization routes of (19z) and (19z, 19x). Selection of each operation of the motor drive circuit 44a and the motor drive circuit 44b is appropriately set as described in the first embodiment.
[0039]
Current sensors (52a-1 to 52a-3, 52b-1 to 52b-3) for detecting a motor current and F in response to changes in the brushless motor 19 and the motor drive circuits 44a and 44b for three-phase AC output. / S relays (46a-1 to 46a-3, 46b-1 to 46b-3) are also provided three by three.
[0040]
In the configuration of the control device 22 according to the above-described second embodiment, when the assist motor is the brushless motor 19, an electric connection portion from the steering torque detection unit 20 to the control device 22, a three-phase motor current output motor Since each of the motor drive circuit section including the drive circuits 44a and 44b and the power supply path from the battery 50 to the motor drive circuits 44a and 44b is divided into two paths (duplex) based on a parallel connection relationship, any one of the paths is used. Therefore, even if a failure occurs, the electric power steering device can be operated on the remaining route, and the system can be prevented from being down due to the provision of the redundant system.
[0041]
Next, a specific configuration of the control device 22 according to the third embodiment of the present invention will be described with reference to FIG. 5, the same reference numerals are given to substantially the same elements as those described in FIG. 3 or FIG. 4, and the description thereof will be omitted. This third embodiment is a modification of the second embodiment. A characteristic configuration according to the third embodiment is that the motor 19 is a brushless motor, and furthermore, double windings for three-phase Y connection are provided.
[0042]
In FIG. 5, the brushless motor 19 includes two three-phase windings (19x-1, 19y-1, 19z-1) and (19x-2, 19y-2, 19z-2) as stators. The three-phase motor current output from the first path motor drive circuit 44a is supplied to the windings 19x-1, 19y-1, and 19z-1, and the three-phase motor current output from the second path motor drive circuit 44b. The phase motor current is provided to windings 19x-2, 19y-2, 19z-2. The supply of the motor current from each of the two motor drive circuits 44a and 44b to the brushless motor 19 is preferably performed simultaneously. Other configurations are the same as those of the second embodiment.
[0043]
In the configuration of the control device 22 according to the third embodiment, when the assist motor is the brushless motor 19, an electric connection portion from the steering torque detection unit 20 to the control device 22, a three-phase motor current output motor The motor drive circuit section including the drive circuits 44a and 44b, the three-phase winding of the brushless motor 19, and the power supply path from the battery 50 to the motor drive circuits 44a and 44b are respectively connected to two paths based on a parallel connection relationship. (Double), even if a failure occurs at any point, the electric power steering device can be operated on the remaining route, and by providing the redundant system, the system down of the electric power steering device can be prevented. .
[0044]
In the above-described embodiment, an example of the electric power steering device has been described as the steering device. However, it is needless to say that the technical idea of the present invention can be applied to another steering device such as a steer-by-wire system.
[0045]
【The invention's effect】
As is apparent from the above description, according to the present invention, in a steering device such as an electric power steering device, a drive circuit for generating a motor current in a control device is provided in two paths, so that a failure occurs in an electrical connection portion. Even if it occurs, the drive of the motor is controlled by the drive circuit of the remaining path, thereby preventing the system from being down, maintaining the system, and maintaining high system reliability. When the steering device is an electric power steering device, the assist of the manual steering force can always be maintained.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an overall configuration of an electric power steering device as an example of a steering device to which the present invention is applied.
FIG. 2 is a block diagram illustrating an internal configuration of a control device.
FIG. 3 is a configuration diagram showing a first embodiment of a control device for a steering device according to the present invention.
FIG. 4 is a configuration diagram showing a second embodiment of the control device for the steering device according to the present invention.
FIG. 5 is a configuration diagram showing a third embodiment of the control device for the steering device according to the present invention.
[Explanation of symbols]
Reference Signs List 10 electric power steering device 11 steering wheel 12 steering shaft 15 rack and pinion mechanism 19 motor 20 steering torque detection unit 22 control device 31 target current determination units 41a, 41b electric connection units 44a, 44b motor drive circuit

Claims (6)

Torque detecting means for detecting a steering torque, target current determining means for determining a motor current in accordance with the steering torque outputted from the torque detecting means, and a motor in accordance with the motor current determined by the target current determining means A steering apparatus having a redundant system, comprising: a driving circuit section for supplying a current to the steering apparatus; wherein the driving circuit section has two identical driving circuits. 2. The redundant system according to claim 1, wherein the motor is a brushed motor having at least two brush pairs, and the two-path driving circuit is connected to each of the at least two brush pairs. Having a steering device. The motor is a brushless motor. In this brushless motor, coils forming separate electric circuits are doubly wound, and the two-path driving circuit is separately provided for each of the coils forming separate electric circuits. 2. The redundant steering system according to claim 1, wherein a current is supplied. 2. The motor according to claim 1, wherein one motor is provided, and two paths of the driving circuits are provided in parallel with the one motor, and the motor is driven in parallel by two paths of the driving circuits. A steering device having the redundant system described in the above. 2. The apparatus according to claim 1, wherein two target current determining means are provided, and transmission of a detection signal from the torque detecting means is divided into two paths and supplied to each of the two target current determining means. A steering device having a redundant system. 2. The steering system according to claim 1, wherein a connection relationship between the drive circuit unit and a power supply that supplies the motor current is formed by two paths.

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