JP2004064921A - Electric power steering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering apparatus which utilizes the rotation angular velocity of a rotor obtained based on an output signal from a resolver to detect a steering angle, detects any failure in a steering angle sensor based on the detected steering angle, and controls a brushless motor based on a steering angle obtained based on an output signal from the resolver. <P>SOLUTION: In the electric power steering arrangement 10 which uses the three-phase brushless motor 19, the electrical angle of the brushless motor 19 is detected by the resolver, and any failure in the steering angle sensor 20d is detected based on the output of the resolver 23. The electrical angle of the brushless motor 19 is detected by the resolver 23, and the steering angle is detected based on the output of the resolver 23. If the steering angle is estimated to be in the vicinity of the maximum steering angle, a current passed through the brushless motor 19 is reduced. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric power steering apparatus, and more particularly, to an electric power steering apparatus that applies a motor power to a steering system in an automobile steering apparatus to reduce a driver's steering load.
[0002]
[Prior art]
The electric power steering apparatus controls driving of a motor by a motor control unit based on signals output from a steering torque detection unit that detects a steering wheel steering torque and a vehicle speed detection unit that detects a vehicle speed to reduce a steering force. I have. An electric power steering apparatus using a brushless motor as the motor is known. Further, in some cases, in addition to the steering torque detection unit and the vehicle speed detection unit, the motor control unit controls the driving of the motor based on the output of the steering angle sensor that detects the steering angle to reduce the steering force.
[0003]
The electric power steering device using the brushless motor does not cause a decrease or fluctuation in the motor output due to a voltage drop between the brush and the commutator, so that a stable steering assist force can be obtained. Further, since the moment of inertia of the motor is smaller than that of the motor with a brush, a good steering feeling can be obtained at the time of high-speed straight traveling or turning of the steering wheel.
[0004]
However, when a brushless motor is used as the motor, it is necessary to control the amount of motor current supplied according to the rotation angle of the motor instead of the brush and commutator. A motor rotation angle detection unit and a motor current detection unit to be detected are provided, and PWM drive control of the brushless motor is performed based on output signals from the motor rotation angle detection unit and the motor current detection unit. Here, the electrical angle is an angle obtained from the position of the magnet of the rotor, and when there are four pairs of magnets around the rotor so that N poles and S poles are alternately arranged along the rotational direction. The mechanical angle of 90 ° of the rotor, that is, 回 転 rotation of the rotor corresponds to the electrical angle of 360 °. The motor rotation angle detection unit is formed by, for example, a resolver and an RD conversion unit. The signal from the resolver is continuously supplied to an RD (resolver digital) converter. The RD converter calculates an angle (rotation angle) θ of the rotor with respect to the stator in the brushless motor, and outputs a signal corresponding to the calculated angle θ. Further, the RD conversion unit calculates a rotational angular velocity ω of the rotor of the brushless motor with respect to the stator, and outputs a signal corresponding to the calculated rotational angular velocity ω.
[0005]
FIG. 15 is a block diagram of the electric power steering apparatus. Outputs of the steering torque detection unit 300 and the vehicle speed detection unit 301 are input to the motor control unit 302. The brushless motor 303 controlled by the motor control unit 302 is provided with a resolver 304 for detecting the rotation angle of the brushless motor 303.
[0006]
FIG. 16 is a block diagram of another electric power steering device. In this case, in addition to the configuration shown in FIG. 15, the output of the steering angle sensor 305 is also input to the motor control unit 302. Has become.
[0007]
[Problems to be solved by the invention]
However, in the conventional electric power steering device, the steering angle is controlled by the motor control despite the fact that the RD conversion unit outputs the rotor angle and the rotation angular speed that can detect the steering angle based on the output from the resolver. Or a separate steering angle sensor is provided as shown in FIG. 16, and the steering angle from the steering angle sensor is detected and used for motor control. Further, there is no means for detecting a failure of the steering angle sensor. Therefore, when the steering angle sensor fails, there is a problem that it is impossible to determine that the steering angle sensor has failed.
[0008]
An object of the present invention is to solve the above problem by detecting a steering angle using a rotational angular velocity of a rotor obtained based on an output signal from a resolver, and detecting a failure of a steering angle sensor based on the steering angle. It is another object of the present invention to provide an electric power steering device that detects a signal and controls a brushless motor in accordance with a steering angle obtained based on an output signal from a resolver.
[0009]
Means and action for solving the problem
The electric power steering apparatus according to the present invention is configured as follows to achieve the above object.
[0010]
A first electric power steering device (corresponding to claim 1) is an electric power steering device using a three-phase brushless motor, wherein an electric angle of the brushless motor is detected by a resolver, and a steering angle sensor of the steering angle sensor is detected based on an output of the resolver. It is characterized by detecting a failure.
[0011]
According to the first electric power steering device, in the electric power steering device using the three-phase brushless motor, the electric angle of the brushless motor is detected by the resolver, and the failure of the steering angle sensor is detected based on the output of the resolver. Thus, the failure of the steering angle sensor can be reliably determined.
[0012]
A second electric power steering device (corresponding to claim 2) is an electric power steering device using a three-phase brushless motor, wherein an electric angle of the brushless motor is detected by a resolver, and a steering angle is detected based on an output of the resolver. However, when it is estimated that the steering angle is near the maximum steering angle, it is characterized by reducing the current flowing through the brushless motor.
[0013]
According to the second electric power steering device, in the electric power steering device using the three-phase brushless motor, the electric angle of the brushless motor is detected by the resolver, and the steering angle is detected based on the output of the resolver. When it is estimated that the steering angle is near the maximum steering angle, the current flowing through the brushless motor is reduced, so that heat generation in the motor control unit can be suppressed, and good control of the electric power steering device can be performed.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[0015]
The overall configuration of the electric power steering apparatus according to the present invention, the main configuration of the mechanical mechanism, and the layout of the electronic circuit unit will be described with reference to FIGS.
[0016]
FIG. 1 is an overall configuration diagram of an electric power steering device according to a first embodiment of the present invention. The electric power steering device 10 is configured to apply an auxiliary steering force (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. 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 brushless motor 19 is provided for the steering shaft 12 via a power transmission mechanism 18. The brushless motor 19 outputs a torque (torque) for assisting the steering torque, and applies the torque to the steering shaft 12 via the power transmission mechanism 18. The steering shaft 12 is provided with a steering torque detector 20. The steering torque detector 20 detects the steering torque applied to the steering shaft 12 when the steering torque generated by the driver operating the steering wheel 11 is applied to the steering shaft 12. Reference numeral 20b denotes a steering angle sensor that detects a steering angle, 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 formed of a computer. The control device 22 receives the steering torque signal T output from the steering torque detection unit 20, the steering angle signal output from the steering angle sensor 20d, and the vehicle speed signal V output from the vehicle speed detection unit 21, and obtains information on the steering torque. A drive control signal SG1 for controlling the rotation operation of the brushless motor 19 is output based on the information on the steering angle and the information on the vehicle speed. Further, the brushless motor 19 is provided with a motor rotation angle detection unit 23 constituted by a resolver or the like. The rotation angle signal SG2 of the motor rotation angle detection unit 23 is fed back 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.
[0017]
In the above description, the electric power steering device 10 adds a steering torque detection unit 20, a steering angle sensor 20d, a vehicle speed detection unit 21, a control device 22, a brushless motor 19, and a power transmission mechanism 18 to a normal steering system configuration. It is constituted by that.
[0018]
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 steering angle sensor 20d detects the steering angle and outputs a steering angle signal to the control device 22. Further, 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. The control device 22 generates a motor current for driving the brushless motor 19 based on the steering torque signal T, the steering angle signal, and the vehicle speed signal V. The brushless motor 19 driven by the motor current applies an auxiliary steering force to the steering shaft 12 via the power transmission mechanism 18. By driving the brushless motor 19 as described above, the driver's steering force applied to the steering wheel 11 is reduced.
[0019]
FIG. 2 shows a main part of a mechanical mechanism of the electric power steering apparatus 10 and a specific configuration of an electric system. A part of the left end and the right end of the rack shaft 14 is shown in cross section. The rack shaft 14 is accommodated in a cylindrical housing 31 arranged in the vehicle width direction (the left-right direction in FIG. 2) so as to be slidable in the axial direction. Ball joints 32 are screw-connected to both ends of the rack shaft 14 protruding from the housing 31, and the left and right tie rods 16 are connected to these ball joints 32. The housing 31 includes a bracket 33 for attaching to a vehicle body (not shown), and also includes stoppers 34 at both ends.
[0020]
2, reference numeral 35 denotes an ignition switch, 36 denotes a vehicle-mounted battery, and 37 denotes an alternating current generator (ACG) attached to a vehicle engine. The AC generator 37 starts power generation by the operation of the vehicle engine. The controller 22 is supplied with necessary power from the battery 36 or the AC generator 37. The control device 22 is attached to the brushless motor 19. Reference numeral 38 denotes a rack end that contacts the stopper 34 when the rack shaft moves. Reference numeral 39 denotes a dust sealing boot for protecting the inside of the gear box from water, mud, dust and the like.
[0021]
FIG. 3 is a sectional view taken along line AA in FIG. FIG. 3 clearly shows the support structure of the steering shaft 12, the specific configuration of the steering torque detector 20, the power transmission mechanism 18, the rack and pinion mechanism 15, and the layout of the brushless motor 19 and the control device 22.
[0022]
In FIG. 3, a steering shaft 13 is rotatably supported by two bearing portions 41 and 42 in a housing 24a forming the gear box 24. A rack and pinion mechanism 15 and a power transmission mechanism 18 are housed inside the housing 24a, and a steering torque detector 20 is additionally provided at an upper portion. The upper opening of the housing 24a is closed by a lid 43, and the lid 43 is fixed by bolts 44. The pinion 13 provided at the lower end of the steering shaft 13 is located between the bearings 41 and 42. The rack shaft 14 is guided by a rack guide 45 and is pressed toward the pinion 13 by a contact member 47 urged by a compressed spring 46. The power transmission mechanism 18 is formed by a worm gear 49 fixed to a transmission shaft 48 connected to an output shaft of the brushless motor 19 and a worm wheel 50 fixed to the steering shaft 12. The steering torque detection unit 20 includes an electronic circuit unit 20b that electrically processes a detection signal output from a steering torque detection sensor 20a disposed around the steering shaft 12. The steering torque detection sensor 20a is attached to the lid 43.
[0023]
FIG. 4 is a sectional view taken along line BB in FIG. FIG. 4 shows a specific configuration inside the brushless motor 19 and the control device 22.
[0024]
The brushless motor 19 includes a rotor 52 made of a permanent magnet fixed to a rotation shaft 51 and a stator 54 disposed around the rotor 52. The stator 54 includes a stator winding 53. The rotating shaft 51 is rotatably supported by the two bearing portions 55 and 56. The tip of the rotating shaft 51 is the output shaft 19a of the brushless motor 19. The output shaft 19a of the brushless motor 19 is connected to a transmission shaft 48 via a torque limiter 57 so that rotational power is transmitted. As described above, the worm gear 49 is fixed to the transmission shaft 48, and the worm wheel 50 that meshes with the worm gear 49 is disposed. At the rear end of the rotation shaft 51, the above-described motor rotation angle detection unit (position detection unit) 23 that detects the rotation angle (rotation position) of the rotor 52 of the brushless motor 19 is provided. The motor rotation angle detection unit 23 includes a rotor 23a fixed to the rotation shaft 51, and a detection element 23b that detects the rotation angle of the rotor 23a using a magnetic effect. For example, a resolver is used for the motor rotation angle detection unit 23. Motor current is supplied to the stator winding 53 of the stator 54. The above components of the brushless motor 19 are arranged inside the motor case 58.
[0025]
FIG. 5 is a block diagram of the control device 22 described above. The control device 22 includes a motor control unit 100, an integration unit 101, and a failure detection unit 102. Further, a failure display unit 103 is connected to the failure detection unit 102. The motor control unit 100 is basically the same as that described with reference to FIGS. When the failure detection unit 102 determines that the steering angle sensor has failed, the failure detection unit 102 outputs 1 when the failure is not determined. When the failure detection unit 102 does not determine the failure, the motor control unit 100 outputs a signal from the failure detection unit 102. When the value is zero, the state is maintained as it is. When the input from the failure detection unit 102 is 1, the signal of the steering angle sensor 20d is cut off, and the input signal from the vehicle speed detection unit 21 and the input from the steering torque detection unit 20 are input. An input signal switching unit 104 that is switched so as to be controlled by a signal is provided.
[0026]
In FIG. 5, an integrating unit 101 integrates a rotational angular velocity signal obtained from a resolver 23 by an RD conversion unit 23 d and inputs the integrated value to a failure detection unit 102. The rotation angle of the rotor can be obtained from the integrated value obtained by integrating the rotation angular velocity.
[0027]
FIG. 6 is a block diagram illustrating a failure detection unit. The failure detection unit 102 includes an input unit 105, an output unit 106, a CPU 107, and a storage unit 108. In the failure detection unit 102, the steering wheel is turned in advance until the steering angle is maximized, and the steering angle signal from the steering angle sensor 20d at each steering angle when the steering wheel is turned is integrated with the integration unit at each corresponding steering angle. The integrated value obtained from 101 is input, and the integrated value corresponding to each steering angle is stored in the storage unit 108. That is, a map 109 of the steering angle corresponding to each integral value as shown in FIG. 7 is created in the storage area 109 in the storage unit 108. In the map 109 shown in FIG. 7, the horizontal axis indicates the steering angle and the vertical axis indicates the integrated value, and the curve C10 is the map 109 of the steering angle corresponding to each integrated value. If an integrated value is obtained from this map, a steering angle corresponding to the integrated value can be obtained. The failure detection unit 102 obtains a steering angle corresponding to the integral value from the input of the integral value of the rotational angular velocity from the integration unit according to the map 109, and compares the steering angle with the input from the steering angle sensor. Take the difference, if the difference is smaller than a predetermined value, determine that it is normal, output a normal value signal, for example, zero to the motor control unit 100 and the failure display unit 103, if the difference is larger than the predetermined value, It determines that a failure has occurred, and outputs a failure signal, for example, 1 to the motor control unit 100 and the failure display unit 103. The predetermined value here is stored in the storage area 110 of the storage unit 108 in advance.
[0028]
The failure display unit 103 is a device that displays whether or not the steering angle sensor 20d has failed, and includes, for example, a light emitting diode that blinks based on an input signal from the failure detection unit 102, and the like. The light emitting diode may be kept off when the signal from the failure detection unit 103 is zero, and may be lit when the input from the failure detection unit 103 is 1. Thereby, when the light emitting diode is turned on, it is possible to determine that the steering angle sensor is out of order.
[0029]
Next, the operation of the present embodiment will be described with reference to the flowchart of FIG. The output from the resolver 23 is converted by the RD converter 23d, and the rotation angular velocity signal is output to the integration section 101 (step ST10). Integrator 101 calculates an integral value of the rotational angular velocity based on the rotational angular velocity signal output from RD converter 23d (step ST11).
[0030]
The steering angle is obtained from the integrated value using the map stored in the storage unit, and is temporarily stored in the storage area A of the storage unit of the failure detection unit 102 (step ST12), and the output from the steering angle sensor 20d is stored in the storage area of the storage unit. B is temporarily stored (step ST13). A difference is calculated by the CPU from the values of the storage areas A and B (step ST14), and the difference is stored in the storage area C (step ST15). The CPU compares the difference with a predetermined value stored in the storage area 110 of the storage unit (step ST16). As a result, when the difference is smaller than the predetermined value, zero is output to the motor control unit 100 and the failure display unit 103 (step ST17). At that time, the motor control unit 100 keeps that state. In the failure display unit 103, the light emitting diode does not light up. Then, the process returns to step ST10 again to perform the processing.
[0031]
If the difference is equal to or larger than the predetermined value as a result of comparison by the CPU, signal 1 is output to motor control unit 100 and failure display unit 103 (step ST18). At this time, the motor control unit 100 operates the input signal switching unit 104 to cut off the signal from the steering angle sensor 20d, and at the same time, switches to the control based on the values of the steering torque detection unit 20 and the vehicle speed detection unit 21 (step ST19). In the failure display section 103, the light emitting diode is turned on (step ST20).
[0032]
Thus, normal control can be performed even when the steering angle sensor 20d fails, and the operator can be notified of the failure of the steering angle sensor 20d.
[0033]
Next, an electric power steering device according to a second embodiment of the present invention will be described. In the second embodiment, the electric power steering apparatus shown in FIG. 1 does not include the steering angle sensor 20d. Further, the control device 22 is partially modified as described below.
[0034]
As shown in FIG. 9, the control device 22 includes a motor control unit 200, an integration unit 201, a steering angle neutral position determination unit 202, and a steering angle estimation unit 203. 15 and 16, but includes a storage unit 204, a comparison unit 205, and a current limit instruction unit 206. The storage unit 204 stores the current limiting area designated steering angle, and the comparison unit 205 compares the steering angle from the steering angle estimation unit 203 with the current limiting area designated steering angle. When the steering angle is equal to or larger than the designated steering angle, A signal for instructing the motor current to be limited is sent by the current limitation instructing unit 206.
[0035]
In FIG. 9, an integrating unit 201 integrates a rotation angular velocity signal obtained from the resolver 23 by an RD conversion unit 23 d and inputs the integrated value to a steering angle estimation unit 203. The rotation angle of the rotor can be obtained from the integrated value obtained by integrating the rotation angular velocity.
[0036]
The steering angle neutral position determination unit 202 determines a steering angle neutral position. The determining unit 202 has two methods shown in the following two specific examples.
[0037]
First, a first specific example will be described with reference to FIG. Signals from the front left wheel speed sensor 207 and the front right wheel speed sensor 208 are input to the steering angle neutral position determination unit 202 to the input unit 209. The input wheel speed signals of the left and right front wheels are compared by the comparing unit 210. When the vehicle speed signals are different, a signal zero is output from the output unit 211, and when the vehicle speed signals match, 1 is output.
[0038]
FIG. 11 is a block diagram of the steering angle estimation unit. The steering angle estimation unit 203 includes an input unit 212, an output unit 213, a CPU 214, and a storage unit 215. The steering angle estimating unit 203 estimates the steering angle based on the integrated value from the integrating unit 201 and the value from the steering angle neutral position determining unit 202. The steering angle estimating unit 203 has a neutral integration value storage unit 216 that stores the signal from the integrating unit 201 when the signal from the steering angle neutral position determining unit 202 is 1. Further, when the steering wheel is steered to the left, it has a left maximum integration value storage unit 217 for storing an integration value when a maximum torque value is obtained, and a left maximum steering angle storage unit 218 for storing a left maximum steering angle. Further, it has a right maximum integration value storage section 219 for storing an integration value when the maximum torque value is obtained when the right steering is performed, and a right maximum steering angle storage section 220 for storing the right maximum steering angle. The steering angle estimation calculates the difference between the integral value input from the integration unit and the neutral integration value, and calculates the steering angle based on the maximum steering angle by the ratio of the difference to the difference between the maximum integration value and the neutral integration value. Calculate and output the value to the motor control unit.
[0039]
Next, the operation of the present embodiment will be described with reference to the flowchart of FIG. The output from resolver 23 is converted by RD converter 23d, and the angular velocity signal is output to integrator 201 (step ST30). Integrator 201 calculates an integral value of the angular velocity based on the angular velocity signal output from RD converter 23 (step ST31).
[0040]
The integrated value is temporarily stored in the storage area F of the storage section 215 of the steering angle estimating section 203 (step ST32), and the integrated value at the neutral position of the steering angle stored in the neutral integrated value storage section 216 of the storage section 215 is stored. Is calculated and stored (step ST33). The ratio of the difference to the difference between the maximum integration value stored in the left maximum integration value storage unit 217 or the right maximum integration value storage unit 219 and the integration value at the neutral position of the steering angle is calculated, whereby the steering angle is estimated. Is performed (step ST34). The steering angle is compared with the current limiting area steering angle (predetermined value) by the comparing unit of the motor control unit 200 (step ST35). As a result, if the steering angle is smaller than the predetermined value, the current limiting instruction unit 206 keeps the current steering angle as it is. Keep state. At that time, the motor control unit 200 keeps that state.
[0041]
When the steering angle is equal to or larger than the predetermined value as a result of the comparison by the comparing unit, a current limiting command is output from the current limiting instruction unit 206 (step ST36). At that time, the motor current is limited.
[0042]
FIG. 13 shows a change in the steering angle and a change in the target current at that time. FIG. 13A illustrates a change in the steering angle, and FIG. 13B illustrates a change in the target current corresponding to the steering angle. In FIG. 13B, the target current changes as indicated by a curve C20 as the steering angle increases. Then, in the electric power steering apparatus of the present embodiment, when the steering angle increases, the target current as shown by the solid lines C21 and C22 is obtained in the range R10 and the range R11 in the figure, and the motor current is limited. Dotted lines C23 and C24 show changes in the target current in the conventional electric power steering device.
[0043]
As described above, the excessive current at the time of the maximum torque is reduced, and the heat generation of the control device can be suppressed.
[0044]
Next, a second specific example will be described with reference to FIG. The steering angle neutral position determination unit 202 includes a torque determination unit 221 and an angular velocity determination unit 222. A signal from the steering torque detection unit 20 and an angular velocity signal from the RD conversion unit 23d are input to the input unit 223. The steering angle neutral position determining unit 202 outputs a 2-bit signal 10 from the output unit 224 when the locked state is in the right direction, that is, when the input steering torque is the maximum torque in the right direction and the angular velocity is zero, In the locked state in the direction, that is, when the angular velocity is zero at the maximum torque in the left direction, a 2-bit signal 01 is output, and when the steering torque is smaller than the maximum torque in the right direction and the maximum torque in the left direction, and , And 00 from the output unit 224.
[0045]
The steering angle estimating unit 203 is similar to the first specific example shown in FIG. 11, and estimates the steering angle based on the integrated value from the integrating unit 201 and the value from the steering angle neutral position determining unit 202. When the signal from the steering angle neutral position determining unit 202 is 10, the steering angle estimating unit 203 stores a signal from the right maximum integration value storing unit 219 that stores a signal from the integrating unit, and a signal from the steering angle neutral position determining unit 202. Is 01, a left maximum integrated value storage unit 217 for storing the signal from the integration unit 201 is provided. Further, the right maximum steering angle and the left maximum steering angle are stored in the storage unit 215 in advance. Further, a neutral time integral value storage unit 216 is provided which stores an average value of the right maximum integral value and the left maximum integral value as a neutral time integral value. The steering angle estimation calculates the difference between the integration value input from the integration unit 201 and the neutral integration value stored in the neutral integration storage unit 216, and in the case of right steering, calculates the difference between the difference and the right maximum integration value or the left. In the case of steering, the steering angle is calculated based on the right maximum steering angle or the left maximum steering angle based on the ratio of the difference between the left maximum integration value and the neutral integration value, and the value is output to the motor control unit 200.
[0046]
The operation of the motor control unit after the estimation of the steering angle is the same as that of the first specific example, and thus the description is omitted.
[0047]
In the present embodiment, the rotation angle is estimated by detecting the angular velocity of the output from the resolver by the RD conversion unit and integrating the angular velocity, but the rotor is determined by the electrical angle output from the RD conversion unit. One rotation may be generated for each rotation, and the rotation angle may be estimated by counting the number of rotations of the rotor based on the number of pulses.
[0048]
【The invention's effect】
As apparent from the above description, the present invention has the following effects.
[0049]
In an electric power steering device using a three-phase brushless motor, the electrical angle of the brushless motor is detected by a resolver, and the failure of the steering angle sensor is detected based on the output of the resolver. be able to.
[0050]
In an electric power steering device using a three-phase brushless motor, the electric angle of the brushless motor is detected by a resolver, and the steering angle is detected based on the output of the resolver, and it is estimated that the steering angle is near the maximum steering angle. In this case, since the current flowing through the brushless motor is reduced, heat generation in the motor control unit can be suppressed, and excellent control of the electric power steering device can be performed.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an electric power steering device according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a main part of a mechanical mechanism of the electric power steering device and a specific configuration of an electric system.
FIG. 3 is a sectional view taken along line AA in FIG. 2;
FIG. 4 is a sectional view taken along line BB in FIG. 3;
FIG. 5 is a block diagram of a control device.
FIG. 6 is a block diagram illustrating a failure detection unit.
FIG. 7 is a graph showing a map of a steering angle corresponding to each integral value.
FIG. 8 is a flowchart illustrating the operation of the present embodiment.
FIG. 9 is a block diagram of a control device.
FIG. 10 is a diagram illustrating a first specific example of a steering angle neutral position determination unit.
FIG. 11 is a block diagram of a steering angle estimation unit.
FIG. 12 is a flowchart illustrating the operation of the present embodiment.
FIG. 13 is a graph showing a change in the steering angle and a change in the target current at that time.
FIG. 14 is a diagram illustrating a second specific example of the steering angle neutral position determination unit.
FIG. 15 is a block diagram of a conventional electric power steering device.
FIG. 16 is a block diagram of another conventional electric power steering apparatus.
[Explanation of symbols]
10 Electric power steering device
11 Steering wheel
12 Steering axis
18 Power transmission mechanism
19 Brushless motor
20 Steering torque detector
20d steering angle sensor
22 Control device
23 Motor rotation angle detector (resolver)
100 Motor control unit
101 Integrator
102 Failure detection unit
103 Failure display section
104 Input signal switching section
200 Motor control unit
201 Integrator
202 Steering angle neutral position determination unit
203 Steering angle estimator

Claims (2)

In an electric power steering device using a three-phase brushless motor,
The electrical angle of the brushless motor is detected by a resolver,
An electric power steering apparatus, wherein a failure of a steering angle sensor is detected based on an output of the resolver. In an electric power steering device using a three-phase brushless motor,
The electrical angle of the brushless motor is detected by a resolver,
Detecting a steering angle based on the output of the resolver,
An electric power steering apparatus, wherein when it is estimated that the steering angle is near the maximum steering angle, a current flowing through the brushless motor is reduced.

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