JP2003026020A - Electric power steering device and control method when detecting abnormality used therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in an electric power steering device provided with a motor for giving an auxiliary force to a steering shaft to control its torque wherein steering wheel operation becomes heavy suddenly because the control of the electric motor is immediately stopped for safety when detecting an abnormality and it is dangerous on the contrary. SOLUTION: When the contents of abnormality are an abnormality of a position (angle detection) sensor 22 of the electric motor 20 and an abnormality of a current of one phase of the electric motor 20, the control of the electric motor 20 is not stopped immediately even when detecting an abnormal condition, and the control of an angle of the electric motor at which angle detection of the position sensor 22 is effective or an effective current of a winding wire is continuously performed to ensure a torque output in a certain angle scope of the electric motor and ensure an auxiliary force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus that mounts an electric motor on a steering shaft to apply a steering assist force.

[0002]

2. Description of the Related Art FIG. 15 schematically shows the structure of a conventional electric power steering apparatus. In the following description, the case where the present invention is used in a vehicle will be described as an example. Therefore, the conventional example will be described as an example in which the present invention is also used in a vehicle. However, the present invention can be used in other moving bodies such as ships. You can also 1 in the figure
Is a steering wheel for steering, and a steering force applied to the steering wheel 1 by a driver (not shown) is a steering input shaft (hereinafter also referred to as a steering shaft).
2 and a steering output shaft (hereinafter also referred to as a steering shaft) 6 and transmitted to a rack and a tie rod 7 via a universal joint and a steering gear 7'to steer steered wheels (not shown). The rack and the tie rod 7 convert the rotational movement transmitted to the steering shafts 2 and 6 into a linear movement. 20 is a steering shaft 2
Alternatively, it is a brushless electric motor (hereinafter, simply referred to as an electric motor or a motor) attached to 6. Brushless motor 20
The assisting force (also referred to as assisting force) generated from is transmitted to the output-side steering shaft 6 via the reduction gear 4, and an assisting force is generated during steering to reduce the steering force felt by the driver.

The controller 130 is supplied with power from the battery 11 via the ignition switch 12, supplies current to the brushless motor 20, and also supplies power to the controller 130 by inputting the ignition switch to the electric power steering. The device starts working.

The torque sensor 3 is arranged between the steering input shaft 2 and the steering output shaft 6, and detects the twist angle between the steering input shaft 2 and the steering output shaft 6, for example, to detect the steering input shaft 2. Steering torque applied to 2 (also called steering force)
Is to detect. The signal from the torque sensor 3 is input to the controller 130. Further, the vehicle speed sensor 13 detects the speed of the vehicle on which the electric power steering device is mounted, and inputs the signal to the controller 130. The steering operation is assisted by transmitting the torque of the electric motor to the steering gear device by controlling the rotation of the electric motor 20 according to the steering torque acting on the steering shaft by the driver's steering wheel operation. When the abnormality of 20 and its control circuit is detected, the relay on the circuit for driving the electric motor is cut off to stop the power supply. Also, the electromagnetic clutch that transmits the torque of the electric motor to the steering gear device is disconnected. As described above, the load for rotating the electric motor is prevented from affecting the steering operation when the electric motor and its control circuit are abnormal.

In the conventional configuration, when it is detected that an abnormality has occurred in the motor or the like even during traveling, the power steering is suddenly changed to the manual steering. The driver, who has become power steering, suddenly switches to manual steering, and performs awkward steering until the driver feels a lot of discomfort. In addition, a driver with weak strength may be incapable of steering. A conventional example for solving this will be described. The one shown in FIG.
FIG. 3 is a schematic block diagram of an electric power steering device similar to that disclosed in Japanese Patent Publication No. 257770. In the figure, reference numeral 60 is a torque signal generation circuit that receives a torque, a speed, and an angle θH and generates a torque signal that commands the electric motor 20, and 64 is a current control circuit that converts the torque command signal into a current value of the electric motor. 24 is an encoder that is attached to the electric motor 21 and outputs an angle signal; 73 is an encoder check circuit that ticks whether the encoder output is normal or abnormal;
Reference numeral 43 is a rotation detection circuit that outputs a signal corresponding to the rotation speed or the rotation angle based on the signal of the encoder 24, and 45 is an up / down counter that counts the signal (pulse) of the rotation detection circuit 43. Further, 51 is a differentiating circuit for differentiating the input angle signal θH, 53 is a positive / negative judging circuit for detecting the direction of change of the angle signal, and 77 is a signal selecting circuit for passing only one effective signal.

Next, the operation will be described. Encoder 2
In order to obtain the same feeling as when the electric motor 21 is normal, when the electric motor 21 cannot be controlled by the encoder 24 due to a malfunction of the encoder 2,
4 is normal, the rotation detection circuit 43 causes the encoder 24
The rotation direction and the rotation speed of the rotor of the electric motor 21 are detected by using the respective phase pulse signal trains ΦA, ΦB, and ΦZ signals from, and the detection result is fed back to control the rotation of the electric motor 15. When the encoder 24 is abnormal and a normal signal is not input to the selection circuit 77, the differentiation circuit 51 and the positive / negative determination circuit 53 determine the rotation direction and the rotation speed of the steering shaft based on the steering angle θH (the rotation position of the steering shaft). The detected one is selected by the selection circuit 77, and the rotation of the electric motor 21 is controlled by the detection result. As described above, when the motor rotation sensor (encoder) has an abnormality, a sensor that can serve as a substitute is separately provided, and the substitute sensor is used to perform the substitute control.

In addition, as disclosed in Japanese Unexamined Patent Publication No. 10-181617, when an abnormality occurs such that one-phase line of a multi-phase (or multi-pole) motor is broken, the control system is changed to drive the motor. There is also one that reduces the current to reduce the feeling of strangeness when an abnormality occurs.

[0008]

As described above, in the conventional electric power steering apparatus, a separate sensor is required to continue the assist control after the abnormality is detected, and the entire apparatus becomes an expensive system. . Also,
To minimize the difference between the normal state in which all phases are energized and the abnormal state in which one phase that is broken is not energized,
It is necessary to reduce the motor current by changing the energization amount of the phase that has not been broken. In this method, it is applicable to a three-phase brushless motor that only affects one phase and breaks the other phases. I can't. The same applies to multi-pole DC motors and induction motors.

The present invention is intended to solve such a problem, and when an abnormal state occurs, the assist is suddenly stopped and the manual steering state is brought about, resulting in a difficult steering state. This can be prevented, and the device can be configured at low cost without newly providing a sensor. Furthermore, the present invention provides an electric power steering device that is not only applicable to brushless motors with four or more phases, but can also continue assist control after detecting an abnormal condition for multi-pole DC motors and multi-phase motors. The purpose is to do.

[0010]

According to the present invention, there is provided a control method for detecting an abnormality in an electric power steering system, wherein torque of an electric motor connected to a steering shaft is controlled to control a steering force applied to the steering shaft. A torque control procedure for assisting, a torque zero control procedure for controlling the torque of the electric motor to zero, a position detecting procedure for detecting a rotational angle position of the electric motor, and an amplitude value of a position signal output by the position detecting procedure is An abnormality detection procedure that detects an abnormality in the position detection procedure based on the presence / absence of a value that varies depending on the rotational angle position and becomes lower than a predetermined value, and after the abnormality in the position detection procedure is detected by the abnormality detection procedure. , The torque control procedure is executed at the rotation angle position where the amplitude value of the position signal becomes equal to or higher than a predetermined level according to the change of the rotation angle position of the electric motor. Output a torque for assisting the steering force, and at the rotation angle position of the electric motor where the amplitude value of the position signal becomes a predetermined level or less, the torque zero control procedure is executed to make the output torque zero. Is included.

An electric power steering apparatus according to the present invention is an electric motor which is connected to a steering shaft so as to be able to transmit power to give an auxiliary force, a position sensor which detects a rotational angle position of the electric motor, and a drive which controls a current flowing through the electric motor. A circuit, a torque sensor for detecting a steering force applied to a steering shaft by a driver steering the steering shaft, a driving direction and a magnitude of an auxiliary force of the electric motor are determined from a torque signal of the torque sensor, A controller that outputs a current command signal that generates this auxiliary force to a drive circuit, the electric motor, the position sensor, the drive circuit, and the torque sensor,
When the operation of the controller is monitored, and the torque sensor is normal and an abnormality is detected in any other one, the content of the abnormality is analyzed and the direction of the assist force output by the electric motor is the steering force. It is provided with a first abnormality determining means for determining whether or not there is a possibility that the direction does not coincide with the direction of No. 1, and when determining that there is no fear, causing the controller to output the current command signal and output the auxiliary force from the electric motor. is there.

Further, an electric motor which is connected to the steering shaft so as to be capable of transmitting power and applies an auxiliary force to the steering shaft, a position sensor which detects a rotational angle position of the electric motor, a drive circuit which controls a current flowing through the electric motor, and a driver. A torque sensor that detects a steering force generated on the steering shaft by steering the steering shaft, and a driving direction and a magnitude of the auxiliary force of the electric motor are determined from a torque signal of the torque sensor, and the auxiliary force is supplied to the drive circuit. A controller that outputs a current command signal that generates a force, the electric motor, the position sensor, the drive circuit, the torque sensor, and the operation of the controller is monitored, and the torque sensor is normal, the electric motor, the If an abnormality is detected in any of the position sensor, the drive circuit, and the controller, the content of the abnormality is analyzed and the abnormality is detected in the electric motor. If it is determined that the abnormality does not occur depending on the turning angle position and there is no risk that the direction of the assisting force does not coincide with the direction of the steering force, the controller is instructed by a current command according to the rotation angle position of the electric motor. It is provided with a second abnormality determination means for outputting a signal and outputting the auxiliary force from the electric motor according to the rotational angle position.

Further, the electric motor is a multi-phase AC electric motor having three or more phases, and the first or second abnormality judging means is one of the multi-phase windings of the electric motor or one of the power supply lines to the electric motor. The wire breakage in the book is determined to be an abnormality in which the direction of the assisting force output by the electric motor does not coincide with the direction of the steering force.

Further, the drive circuit outputs a three-phase alternating current, and the first or second abnormality determining means outputs the output voltage drop of one phase of the three-phase alternating current output from the electric motor. It is determined that there is no risk that the direction of the assisting force that does not coincide with the direction of the steering force is abnormal.

Further, the first or second abnormality determination means is such that the abnormality generated in the position sensor is such that the direction of the auxiliary force output from the electric motor does not become inconsistent with the direction of the steering force. It is determined that

The contents of the abnormality of the controller are as follows:
It is one in which the current cannot be output to one phase of the electric motor.

Further, it is determined that the abnormality detected by the first or second abnormality determining means is an abnormality in which there is no risk of reversal in the direction of the auxiliary force output by the electric motor,
After the controller continues to output the current command signal,
There is provided a disconnecting means for disconnecting power supply to the electric motor when a predetermined condition is satisfied.

The predetermined condition is that a predetermined time elapses after the first or second abnormality determination means detects an abnormality.

Further, when the steering force when the first or second abnormality determining means detects an abnormality is equal to or more than a predetermined value set in advance, the steering force is changed to the predetermined value or less. The predetermined conditions are set.

Further, when the steering force at the time when the first or second abnormality determining means detects an abnormality is less than or equal to a predetermined value set in advance, the steering force is changed to exceed the predetermined value. The predetermined conditions are set.

Further, when the electric current of the electric motor at the time point when the first or second abnormality judging means detects an abnormality is equal to or more than a predetermined value set in advance, the current may be changed to the predetermined value or less. The predetermined conditions are set.

Further, when the current of the electric motor at the time when the first or second abnormality determining means detects an abnormality is less than or equal to a predetermined value set in advance, the current may be changed to the predetermined value or more. The predetermined conditions are set.

Further, a vehicle speed sensor for detecting the vehicle speed is provided,
When the vehicle speed when the first or second abnormality determination means detects an abnormality is equal to or higher than a predetermined first predetermined value, the vehicle speed is changed to be equal to or lower than the first predetermined value. This is a predetermined condition.

Further, a vehicle speed sensor for detecting the vehicle speed is provided,
When the vehicle speed when the first or second abnormality determination means detects an abnormality is equal to or higher than a second predetermined value set in advance, the electric motor is provided while the vehicle speed is equal to or higher than the second predetermined value. The torque of is controlled to zero.

Further, a rotation speed sensor for detecting the engine rotation speed is provided, and the predetermined condition is that the engine rotation speed falls below a predetermined value.

Further, when the first or second abnormality judging means does not detect the abnormality, the circuit operation is stopped after a predetermined time has elapsed since the ignition key switch was turned off. The predetermined condition is that the state of the ignition key switch is turned off when the first or second abnormality determination means detects an abnormality.

Further, after the first or second abnormality determining means detects an abnormality, until the predetermined condition is satisfied and the operation of the electric power steering device is stopped, a voice, a lamp, a buzzer, or A warning means for warning the driver by displaying an image is provided.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Hereinafter, the electric power steering device according to the first embodiment of the present invention will be described. 1 is a schematic configuration diagram showing a configuration of an electric power steering device 100 according to a first embodiment of the present invention. In the following description, the case where the present invention is used in a vehicle will be described as an example, but the present invention can be used in other moving bodies such as ships. In the figure, reference numeral 1 denotes a steering wheel for steering, and a steering force applied to the steering wheel 1 by a driver (not shown) is applied to a steering input shaft (hereinafter also referred to as steering shaft) 2 and a steering output shaft (hereinafter referred to as steering shaft). (6) and is transmitted to the rack and the tie rod 7 via the universal joint and the steering gear 7'to steer the steered wheels (not shown). The rack and the tie rod 7 convert the rotational movement transmitted from the steering shafts 2 and 6 into a linear movement. Reference numeral 20 denotes a brushless motor (hereinafter also referred to as a motor) mounted on the steering shaft 2 or 6. The assist force generated from the brushless motor 20 is transmitted to the output-side steering shaft 6 via the reduction gear 4, and the assist force is generated during steering to reduce the steering force felt by the driver.

The controller 30 is supplied with power from the battery 11 via the ignition switch 12, supplies current to the brushless motor 20, and also supplies power to the controller 30 by inputting the ignition switch to the electric power steering. Device 1
00 starts operating. The torque sensor 3 is the steering input shaft 2
Disposed between the steering input shaft 2 and the steering output shaft 6, and detects the steering torque applied to the steering input shaft 2 by detecting the twist angle between the steering input shaft 2 and the steering output shaft 6, for example. Is. The signal from the torque sensor 3 is input to the controller 30. Further, the vehicle speed sensor 13 detects the speed of the vehicle on which the electric power steering device 100 is mounted, and inputs the signal to the controller 30. Reference numerals 98 and 99 denote first and second worm lamps, the details of which will be described later.

FIG. 2 shows a detailed block diagram of the brushless motor 20 and the controller 30 shown in FIG. The brushless motor 20 includes a three-phase synchronous permanent magnet motor 21 and a position sensor 22 (for example, a resolver) that detects a magnetic pole position (rotor angle). The magnetic pole position information detected by the position sensor 22 is input to the controller 30.

The controller 30 inputs a signal from the position sensor 22 which detects the rotational position of the motor 20, and the position detection circuit 37 calculates the motor position θ. Further, the current detection circuit 36 detects the current flowing in each phase of the permanent magnet motor 21 as the current flowing in each phase of U, V and W. The q-axis and d-axis detection currents are obtained by dq conversion from the motor position and the U, V, W phase detection currents by the two-phase conversion circuit 38. Further, on the map 31 in which the motor drive torque to be output is stored in advance, the motor drive instruction current (target q-axis current) is calculated based on the signal from the torque sensor 3 and the signal from the vehicle speed sensor 13. The well-known PI control 32 calculates the deviation between the target q-axis current and the actually detected detected q-axis current to obtain the q-axis command voltage. Similarly, set the target d-axis current to 0,
The deviation from the detected d-axis current is calculated by the well-known PI control 33 to obtain the d-axis command voltage. By performing the three-phase conversion 34, that is, the dq inverse conversion, the command voltages of the d and q axes are converted into command voltages of the motor three phases, U, V, and W phases. These 3
The phase command voltage is PWM-modulated and F is applied to the FET drive circuit 35.
Instruct ET drive. The FETs 41 to 46 receive the FET drive signal and realize chopper control. As a result, a current flows through each phase of the permanent magnet motor 21 to generate torque,
Generates steering assist force.

The abnormality judging means 40 turns the ignition ON.
When the control is started, the control for starting the assist control is also performed. At the start of the control, the FET drive circuit 35 is instructed to start the drive and the relay 39 is turned on.
The relay 39 is turned on to apply the supply voltage to the FETs 41 to 46, and by issuing a drive instruction to the FET drive circuit 35, the FETs 41 to 46 start ON / OFF drive and current starts to flow in the permanent magnet motor 21.

Further, when an abnormality occurs in the electric power steering device 100 and the abnormality is detected, the abnormality determining means 40 analyzes the content of this abnormality and assists in the opposite direction against the driver's intention, that is, When it is determined that the motor does not act as the braking torque in the direction that disturbs the driver's operation of the steering wheel, the control is continued, that is, when it is determined that the direction of the driving force of the motor is not wrong, the control is continued. The transfer determination means 40 having the above functions is referred to as the first abnormality determination means according to the present invention. However, when the torque sensor 13 fails and outputs an erroneous torque sensor signal, the FET 41 operates in the case of a dangerous failure such that the motor is arbitrarily driven and the steering wheel 1 is rotated unlike the intention of the driver. ~ 46
Of the permanent magnet motor 21 is instructed so that no current flows in each phase of the permanent magnet motor 21. Further, the relay 39 is turned off to stop the operation of the electric power steering device 100 itself. The relay 39 is the breaking means referred to in the present invention.

The position detecting sensor 22 of the motor, for example, the resolver, excites one of the two coils by the periodic signal sinωt as shown in FIGS. Inducing the other, two-phase amplitude modulation signals sinθsinωt and cosθsin depending on the motor position θ
Output ωt. When this signal is synchronously detected, x
= Asin θ, and y = Acos θ. Therefore, the motor position θ is obtained by calculating tan ⁻¹ (x / y).

Here, when θ = 0, naturally x = 0, but one of the induced signals generated from the position detection sensor 22
Even when sin θ sin ωt is not output due to disconnection, x
Since = 0, depending on the position of θ, if x or y is monitored and its amplitude is not normal ((d) in FIG. 3), it is impossible to detect the abnormality. Even in this case, since the motor rotates, eventually
It is possible to detect a failure when θ is around 90 or 270 degrees. Conventionally, the operation of the electric power steering device is stopped at the time when the abnormality can be detected in this way, and the abnormal control is not performed. It was Of course, there is no recovery from a stopped state due to an abnormality until it becomes normal after repairs.

On the other hand, in the present invention, the abnormality determining means 40
When an abnormality is detected in the position detection sensor 22, when the angle of the position sensor 22 is in the vicinity of θ = 0, the position of θ can be apparently detected even though it is abnormal. There is no need to immediately stop the operation of the electric power steering device 100, because the phenomenon of assisting in the opposite direction of the driver's intention or outputting the braking torque to hinder the steering wheel operation does not occur. However, when the angle is in the vicinity of θ = 90 and 270 deg, if the position sensor 22 is abnormal, the motor position cannot be detected (the signal output is weak and a normal angle signal cannot be obtained). Therefore, control is performed using this signal. By mistake,
There is a possibility of assisting in the opposite direction or controlling the motor as braking torque, which is dangerous.
The motor drive is interrupted only while it is in the vicinity of 0 and 270 degrees.

Therefore, as shown in FIG.
When an abnormality of the position sensor 22 is detected, θ = 0, 180de
When it is in the vicinity of the position of g, the motor drive is continued without stopping the device immediately, and when it reaches the vicinity of θ = 90, 270 deg, the motor drive is temporarily interrupted. When the motor further rotates and comes to around 0 or 180 degrees again, the motor drive is restarted. Motor position θ = 90, 270 where the motor position cannot be detected when an abnormality is detected
When it is near deg, the motor drive is stopped immediately,
After that, when the motor rotates and the rotational angle position becomes around 0 and 180 degrees, the control is restarted and continued. For convenience of description in each of the following embodiments, the angle of 0 degrees described above,
The control method in which the drive control is performed near 180 degrees and the drive control is not performed near 90 degrees and 270 degrees is called conditional control based on the motor angular position. Of course, when the above drive control is not performed, the electric power steering device is not completely stopped, but the drive can be restarted at any time when the angular position falls within the controllable range. It is controlled and waiting. In addition, the neighborhood and the neighborhood mentioned above are plus or minus 4
This is a range of about 5 degrees. Abnormality determination means 40 having a function of conditional control based on the motor angular position
Is referred to as the second abnormality determining means referred to in the present invention. The conditional control based on the motor angular position is the abnormal time control procedure referred to in the present invention.

In this conditional control based on the motor angular position, although it is not continuous even if an abnormal state occurs, steering assist can be obtained, and when the abnormal state occurs, the assist force disappears at all. Then, the driver does not have difficulty in steering, and it is not necessary to newly provide a sensor as a device, so that the system can be constructed at low cost.

The abnormality judging means 40 makes an abnormality judgment,
When continuing the conditional control based on the above-mentioned motor angular position, in order to notify the driver that an abnormality has occurred, a voice such as turning on the first warning lamp 98,
The driver is warned and notified that an abnormality has occurred by a lamp, a buzzer, or an image display, and further, by vibrating the steering wheel.

Further, the conditional control based on the motor angular position is continued only within a predetermined time after the abnormality is detected, and after the predetermined time has elapsed, the relay 39 is turned off to turn on the electric power steering system. Stop the operation. According to the present invention, a grace period is suddenly set from the power steering to the manual steering, which gives the driver a preparation period for shifting to the manual steering without a feeling of discomfort, and also allows the driver to drive forever in an abnormal state. By continuing the above, the secondary failure is prevented from spreading. At this time, the second warning lamp 99 is turned on to notify that the assist control has been lost.

The flow of the above control will be described with reference to the flow charts of FIGS. Ignition key 12 is O
When the result is N, electric power is supplied to the electric power steering apparatus 100, the controller 30 is activated, and control is started from step S1. In step S1, control for starting the assist control is performed, and when the control is started, the FET drive circuit 35 is instructed to be driven and the relay 39 is turned on. The relay 39 which received the instruction is turned on, and the FETs 41 to 46 are turned on.
The FET 41 to 46 starts ON / OFF drive by applying a drive voltage to the FET drive circuit 35 and a current starts to flow in the brushless motor 21.

In step S2, the three-phase current is detected from the current detection circuit 36. At this time, the current may be detected in any two phases. For the remaining one phase,
Calculated from the sum of the other two phases. In step S3,
The motor position is detected by the motor position sensor 22. This is called a position detection procedure. In step S4, the three-phase current is converted from the two-phase conversion means 38 into a current vector in the d and q axis coordinate systems. In step S5, a torque sensor signal is input from the torque sensor 3. In step S6,
The vehicle speed is calculated from the vehicle speed information obtained from the vehicle speed sensor 13.

In step S7, the target steering torque, that is, the motor current is obtained from the map calculation processing 31 from the map of the torque sensor signal and the vehicle speed. In step S8, the target motor current and the q-axis motor current related to the torque detected in step S3 are fed back, and the q-axis target voltage for driving by the PI compensation 32 is obtained. Further, as a rule, the d-axis motor current detected in step S3 is fed back so that the d-axis motor current is set to 0, and the PI compensation 33 determines the d-axis target voltage. In step S9, the calculated d,
To convert the q-axis target voltage into a three-phase target voltage, 3
The phase conversion means 34 performs conversion to obtain target voltages for each of the three phases. In S10, it is determined whether or not there is an abnormality in the system, and if there is an abnormality, processing such as stopping the motor drive is performed. Details of this will be described later with reference to FIG.

In S11, the target voltages of the three phases are PWM-modulated and output to the FET drive circuit 35. FET drive circuit 3
The FETs 41 to 46 are turned on and off by 5 and the motor 2
A desired voltage is applied to the winding of each phase of No. 1, and a current flows between each phase due to the voltage difference of each phase, and a motor torque is generated. By returning to S2 and being repeatedly executed, the assist control can be realized. The flow from step S1 to step S11 is called a torque control procedure. At this time, if the torque signal is set to zero, it is possible to perform zero torque control in which the output is zero while the control circuit is being used.

Details of step S10 (abnormality detection procedure) are shown in FIG. The flow of FIG. 5 will be described. In step S101, it is determined whether the torque sensor 3 is abnormal, for example,
When there is an input outside the range of the signal that is normally output, it is judged to be abnormal. If it is determined to be abnormal, the process proceeds to S106. If the torque sensor 3 is abnormal, the control is immediately stopped, the motor drive is immediately prohibited, and the relay 39 is turned off to bring the system down. This makes it possible to eliminate a dangerous failure mode in which the steering wheel rotates unintentionally against the driver's will.

If no abnormality is found in the torque sensor in step S101, in step S102, as shown in FIG.
As shown in (c) and (d), the amplitude detected by the position detection circuit 37 is extracted from the position sensor 22. Step S1
Check the amplitude at 03. S103 is one of the abnormality detection procedures referred to in the present invention. If the amplitude is normal, normal driving is performed, so the abnormality determination is terminated and the process returns to the original flow (step S11). In step S103,
As shown in FIG. 3D, when the amplitude may be equal to or smaller than a predetermined value, it is determined that an abnormality has occurred somewhere in the position detection circuit including the sensor, and the process proceeds to steps S199 and later. As described above, even if the amplitude is equal to or smaller than the predetermined value, it is not always possible to extract the position signal.
At 99, the position signal is taken out. Then, in step S200, conditional control based on the above-described motor angular position is performed. That is, as shown in (e) of FIG. 3, assist control is performed in the vicinity of angular positions of 0 and 180 degrees, and 90 and 270
In the vicinity of the temperature, the motor is not driven and the standby state is set. The above states are switched one after another as the motor rotates. Step S199 is the position detecting procedure according to the present invention. Then, in step S200A, the first warning lamp 98 is provided to notify the driver that an abnormality has occurred.
Lights up. Then, in step S104, the time during which this abnormal state continues is measured.
Returning to step 9, in S200, drive / standby switching control in an abnormal state is continuously performed. When the predetermined time is reached, the process goes to S106, the subsequent motor drive is prohibited, and the relay 39 is turned off to bring down the system of the entire apparatus.

In step S107, the assist control is stopped due to an abnormal state.
The warning lamp 99 is turned on. At this time, instead of the lamp, the vibration of buzzer, steering, etc., images,
The driver may be notified of the abnormality by voice. The second warning lamp in step S107 and step S200
It may be shared with the first warning lamp of A or may be another indicator lamp (another kind of alarm). The loop control from step S199 to step S104 in FIG. 5 is referred to as an abnormal time control procedure. The failure of the motor angle sensor referred to here includes not only the failure of the motor position sensor 22 such as the resolver but also an abnormal state of the motor position detection circuit inside the controller 30.

Embodiment 2. In the first embodiment, it has been described that the assist control is continued after the abnormality is detected and the assist control is stopped depending on the elapsed time after that. However, in the present embodiment, the driver performs emergency avoidance after the abnormal state occurs. The control may be continued until the vehicle is stopped as a result of the operation, that is, while the vehicle is running after the abnormality is detected. That is, if the steering wheel feels suddenly changed and the feeling of the steering wheel changes while the vehicle is running, there is no room for the driver. Therefore, if the vehicle speed detected by the vehicle speed sensor 13 at the time of abnormality detection is equal to or higher than a predetermined value. When the control is continuously performed and becomes equal to or lower than a predetermined value, for example, a speed that is equal to or less than a predetermined speed close to the stop, the control is stopped and the relay 39 is turned off to prohibit the motor driving.

Since the control of the electric power steering is as described in the first embodiment, the description will be omitted. The overall control flow is also shown in FIG.
It is the same as the flow shown in. Abnormality determination process S1 in FIG.
What is performed according to the second embodiment is shown in the flowchart of FIG.

In FIG. 6, steps S101 to S103 are the same as those in FIG.
When an abnormality is detected in step S110 (step S1
It is determined whether the vehicle speed in 03) is equal to or higher than a predetermined speed (for example, 10 km / h). If the speed is equal to or higher than the predetermined speed, it is determined that the vehicle is traveling, and based on the motor angular position detected in step S199, in step S200, the first embodiment
Conditional control based on the angular position of the motor is performed as described in (1). Then, from step S110 to step S
While repeating 200A, step S1
When the vehicle speed becomes equal to or lower than the predetermined value in 10, it is determined that the speed has decreased to a safe speed even if the assist force disappears, and in step S106, the relay 39 for prohibiting the motor drive is used.
Is turned off to stop the control of the electric power steering device.

If the vehicle speed at the time of detecting the abnormality is originally low in step S110, it is determined that the vehicle has almost stopped, so the assist control is immediately stopped, the relay 39 is turned off, and the motor is driven. It stops (step S106).

Embodiment 3. In the second embodiment, the assist control is continued while the vehicle is running, but the vehicle speed at the time when the abnormality is detected is extremely high (for example, 50 km).
/ H) or more), it is not possible to operate a steering wheel that is too large compared to when operating at low speed, and the steering wheel operating force is small, so in practice, even if the assist torque suddenly disappears The person does not feel any inconvenience. Further, while the assist torque is applied or not applied according to the rotation angle of the motor during the control according to the present invention of the first embodiment, it may be confused by the driver at high speed. Therefore, as described below, the control method thereafter may be switched depending on the time when the abnormality is detected and the magnitude of the vehicle speed thereafter.

FIG. 7 shows a flowchart of the third embodiment. In the figure, step S210 is to determine whether the vehicle speed is higher than a second predetermined value (for example, 50 km / h), that is, whether the steering wheel operation is extremely small and high speed. If the speed is high here, step S2
11, the motor current is controlled to zero so that the assist torque is not generated. Further, in step S212, the third warning lamp is turned on to notify the driver of that fact. While repeating steps S210 to S212, if the driver notices that he / she slows down the vehicle or pushes the vehicle toward the shoulder to stop the vehicle,
At 210, it is determined that the vehicle speed has fallen below the second predetermined value.
Since the subsequent steps are the same as those in the flow chart of FIG. 6 of the second embodiment, detailed description thereof will be omitted. However, as long as the vehicle speed exceeds the first predetermined value (for example, 10 km / h), there is a condition based on the motor angle. Take control. When the vehicle speed falls below the first predetermined value, the operation of the electric power steering device is stopped. After step S200A, the reason why the driver returns to the top of step S210 without returning to the top of step S110 as shown in FIG. 6 is that the driver always confirms (or does not confirm) the lighting of the first warning lamp. This is because the speed is not always decreased, and the speed may be increased to the second predetermined value or higher thereafter.

According to the electric power steering apparatus of the third embodiment, the steering wheel does not become lighter or heavier depending on the angle of the motor during an abnormality during high-speed traveling, and the driver is less confused. The effect is obtained.

Fourth Embodiment Further, the condition for continuing the conditional control based on the motor angular position may be from the detection of the abnormality to the stop of the engine. That is, if the engine speed is less than or equal to a predetermined speed, or if it is determined that the rotation has stopped, or if the ignition switch is turned off, the control is stopped, the motor drive is prohibited, and the relay is stopped. You may make it turn off 39.

The control flow in this case will be described with reference to FIG. The overall flow of the electric power steering control is as shown in FIG. 4 of the first embodiment,
Among them, the abnormality determination processing S10 according to the present embodiment is shown in FIG.
It is shown by the flowchart shown in.

In FIG. 8, only step S111 is different from FIG. 5, and when the engine speed is equal to or higher than a predetermined speed, it is determined that the engine is not stopped, and even if it is determined that the engine is in an abnormal state, step S200 is performed. Control is continued. However, when the engine speed becomes equal to or lower than the predetermined speed, it is determined that the engine is stopped, the motor drive is prohibited and the relay 39 is turned off in step S106.

As another method for confirming the stopped state of the engine, the state of the ignition switch may be used as described above. This is shown in FIG. That is, S112
As shown in the step, when it is determined that the ignition switch is ON and the ignition switch is ON, the control of step S200 is continued. However, when it is determined that the ignition switch is OFF, it is determined that the engine has stopped, the motor drive is immediately prohibited, and the relay 39 is turned off. In addition, to be on the safe side, the electric power steering system generally starts up when the ignition switch is turned on, but it does not turn off immediately when the ignition switch turns off. It is rare. In the operation shown in FIG. 9, the electric power steering apparatus continues to operate when the ignition switch is turned off during normal operation, but an abnormality is detected and step S20 is performed.
It is turned off at the same time when the ignition switch is turned off when the control of 0 is performed.

Embodiment 5. In the processing of step S10 of FIG. 4 of the first embodiment, the condition control based on the angular position of the motor is continued because this abnormality is being steered. It may be limited until the steering is completed. In other words, if an abnormality occurs during steering and the assist torque is suddenly extinguished and the manual steering state is reached, for example,
If the vehicle is turning, the alignment torque of the vehicle is reflected in the steering of the driver, the steering suddenly becomes heavy, and the turning cannot be maintained, which may make steering difficult. Therefore,
When the steering torque at the time of detecting the abnormality is equal to or greater than the predetermined value, the assist control is continued and the motor drive is continued. Then, when the steering torque eventually becomes equal to or less than the predetermined value, it is determined that the steering is completed, the relay 39 is turned off, and the motor drive is stopped. Further, even when the steering torque at the time of detecting the abnormality is equal to or less than the predetermined value, the assist control is similarly continued and the motor drive is continued. However, in this case, when the steering torque exceeds a predetermined value by some operation thereafter, it is determined that the first steering is completed, the relay 39 is turned off, and the motor drive is stopped.

Regarding the flow of control explained above, FIG.
Will be described. The electric power steering control is as described in the first embodiment, and the overall control flow is also the flow shown in FIG. 4, so description thereof will be omitted. Among them, the abnormality determination processing S10 according to this embodiment
Is shown in the flowchart of FIG.

The step of S113 is the same as step S103.
The torque sensor signal at the time when the abnormality is detected is stored as a large value or a small value with respect to a predetermined value determined in advance. If it is large, it is determined that the steering is in progress, and if it is small, it is determined that the vehicle is traveling straight ahead, and step S
At 200, conditional control based on the motor angle is performed. Then, in step S206, it is determined again whether the torque sensor signal is larger or smaller than the predetermined value. Here, step S113
If there is a change as compared with the stored state in (3), it is determined that the steering has ended, the relay 39 is turned off, and the motor drive is stopped.

In step S113, the torque sensor signal is
Even if it is smaller than the predetermined value, for the time being, step S200
At, the conditional control based on the motor angular position is started, and thereafter, this control is continued until the torque signal becomes larger than a predetermined value at step S206. In this case, for example, unless the steering wheel is operated straight from the beginning to the end (when the road surface is horizontal and steering wheel operation is not required), the assist control will not be interrupted even after an abnormality is detected. There is no problem because it is not in the state to say.

Sixth Embodiment The motor current may be used instead of the torque sensor signal of the fifth embodiment. As shown in step S114 of FIG. 11, the magnitude relationship between the motor current and the predetermined value determined at the time when the abnormality is detected is stored. Then, the assist control of step S200 is continued, and thereafter, the magnitude relationship of the electric motor current with respect to the predetermined value is determined again in S207, and if there is a change from the stored one, the steering wheel operation state that was being performed at the time when the abnormality was detected ends. As a result, the relay 39 is turned off to stop the motor drive. When the motor is an AC electric motor, the motor current is more effective as long as it is subjected to a phase calculation process for converting it into an effective torque. Even when the motor current at the time when the abnormality is detected in step S114 is equal to or less than the predetermined value, the assist control is continued in step S200, and then the value is changed to the predetermined value or more in step S207 by some handle operation or the like. When relay 39
Is turned off to stop the motor drive.

Embodiment 7. In addition, in the first to sixth embodiments, the example in which the assist control is continued after detecting the failure of the motor position detection has been described, but the case of the abnormality of the motor unit 20 and its related parts will be described. In a brushless motor, as shown in FIG. 12, when a sine wave is applied to three phases, U phase, V phase, and W phase, regardless of the motor position,
Outputs a constant motor torque. By energizing in this way, the motor is driven and acts smoothly as an assist torque.

However, when an abnormality occurs in the motor 20, for example, on the path for energizing the U phase, or U
When the wire breaks in the motor coil of the phase, as shown in FIG. 13, the current does not flow in the U phase, and the current flows only in the other phases. At this time, the motor output torque varies depending on the motor position. But,
In the case of such a 0 failure, the magnitude of the output torque of the motor changes, but the direction of the generated torque does not change. At least, no reverse torque is generated. Therefore, even if one of the polyphase lines is broken, the assisting in the opposite direction does not occur. Therefore, in this abnormal state, even if the assist control is continued, it does not cause a fatal danger to the driver.

Therefore, in the current detection circuit 36,
The fact that no current is flowing in one phase, for example, the U phase, can be detected except when the position of the motor is near 0 degrees and around 180 degrees, so it can be determined that one phase is broken (0 In the vicinity of 180 degrees, the U-phase current is originally close to zero, so the difference with the target current is difficult to observe, so it cannot be detected). Even if such an abnormality occurs, if the control is continued as the electric power steering device, it does not assist in the reverse direction, and the motor torque is generated although it is small and the torque fluctuation due to the rotation occurs. Therefore, it can act as steering assist.
Therefore, even in an abnormal state, if the normal control is continuously performed, it becomes possible to obtain steering assist, and it is possible to prevent the driver from falling into a difficult steering state.

FIG. 14 shows the flow of control in this embodiment.
Will be described. The electric power steering control method is as described in the first embodiment, and the overall control flow is also the flow shown in FIG. Among them, the abnormality determination processing S10 is shown by the flowchart shown in FIG.

In step S101, the torque sensor 3
Judge abnormalities. For example, the abnormality is determined to be abnormal when there is an input outside the range of the signal that is normally output. If it is determined to be abnormal, the process proceeds to S106. This allows
When the torque sensor 3 is abnormal, the relay 39 is turned off so that the control is not continued, the motor drive is immediately prohibited, and the system goes down. This makes it possible to eliminate a dangerous failure mode in which the steering wheel rotates unintentionally against the driver's will.

In step S120, as shown in FIGS. 12 and 13, when there is a difference between the detected value of the motor current and the target detected value, that is, the target current and the detected current. If the difference is greater than or equal to a predetermined value (except of course when the detected current is zero), it is determined that an abnormality has occurred on one line of the motor line path or one of the windings of the motor. Assist control is performed when the phases are missing. If it is normal in step S120, normal driving is performed, and therefore the abnormality determination is terminated and the process returns to the original flow. The abnormality detection in step S120 is performed for each phase.

In step S104, the time up to the present after the abnormal state is detected is measured, and when it is less than the predetermined time, the control in step S300 is continued. Depending on the change in the angle of the motor, an abnormality may or may not be detected in step S120. Then, the normal state and the state in which the abnormality is detected may repeatedly appear until the predetermined time in step S104. While the abnormality is detected, the assist control of step S300 is performed. However, when it is in a normal state, the motor is driven as usual to assist. When the time exceeds the predetermined time in step S104, the process proceeds to step S106, and the relay 39 is turned off to prohibit the motor driving thereafter, thereby bringing down the system of the entire apparatus.

At S107, since an abnormal state has occurred,
In order to notify the driver of this, a warning lamp indicating that the motor drive is stopped is turned on. In step S300A, a lamp indicating an alarm indicating that control is being continued while an abnormality is detected is turned on. In steps S300A and S107, the driver may be instructed to make an abnormality by vibrating a buzzer, a steering wheel, or the like instead of using the lamp, or by video or audio.

Although the contents of the abnormality have been described here by taking the disconnection of the motor wire as an example, the FET drive unit inside the controller 30, for example, the failure such that any one of the FETs 31 to 36 does not turn on. The same can be said. Therefore, also in this case, it is possible to similarly determine the abnormality and perform the assist continuation control. In addition, the three-phase conversion unit, which is one of the control processes inside the controller 30,
The calculation is performed by the CPU and the signal is output to the drive circuit 35. However, even when the CPU fails and cannot output the signal to the drive circuit 35, the motor cannot be energized. Is effective.

Further, as described in the examples of the first to seventh embodiments, the duration may be adapted to each situation, or the conditions for continuation may be combined.

In the description of each embodiment, the three-phase brushless motor has been described. However, since the control in the disconnection state is the same as the normal control and nothing special is done, the brushless motor having four or more phases is also controlled. The same can be said for multi-pole DC motors and induction motors, as well as being adaptable.

[0075]

As described above, according to the control method for detecting an abnormality of the electric power steering apparatus of the present invention, even if the abnormality is detected, the control for outputting the auxiliary torque is continued depending on the content of the abnormality. Since the control procedure at the time of abnormality is included, it is possible to obtain the effect that the driver does not feel uncomfortable when the abnormality occurs.

According to the electric power steering apparatus of the present invention, when an abnormality is detected, the content of the abnormality is analyzed, and if it is determined that there is no fear of the motor outputting torque in the reverse direction, the torque control of the electric motor is continued. Since the first abnormality determining means is provided, the effect that the driver does not feel uncomfortable when an abnormality occurs can be obtained at low cost.

If the torque sensor is abnormal, the control is immediately stopped, and when other abnormalities are detected, the contents of the abnormality are analyzed, and if it is determined that there is no fear that the motor will output torque in the reverse direction, the torque of the motor will be reduced. Since the second abnormality determining means for continuing the control is provided, the effect that the driver does not feel uncomfortable when an abnormality occurs can be obtained at low cost.

Further, the first or second abnormality judging means is
It is judged that the abnormality that the electric power cannot be supplied to one phase of the electric motor is not for reversing the torque generated by the electric motor, and the torque control is continued. Therefore, it is possible to obtain an effect that the driver does not feel uncomfortable when the electric motor or the electric power supply line fails. .

Further, the first or second abnormality judging means is
It is determined that the abnormality that cannot be output to one phase of the drive circuit is not to reverse the torque generated by the electric motor, and the torque control is continued, so that the driver does not feel uncomfortable when the drive circuit fails.

Further, regarding the abnormality that occurs in the controller that makes it impossible to supply power to one phase of the motor, it is determined that the torque generated by the electric motor is not reversed, and the torque control is continued. It is possible to obtain the effect that the person does not feel a sense of discomfort.

After detecting an abnormality, control is continued,
Since the cutoff means for cutting off the power supply to the electric motor when the predetermined condition is satisfied is provided, the operation of the electric power steering device can be safely stopped.

Further, since the operation of the breaking means is conditioned on the lapse of a predetermined time, it is possible to limit the time during which the electric power steering device operates after the abnormality is detected, which is safe.

Further, the operation of the shut-off means is under the condition that if the value of the steering torque at the time of detecting the abnormality is equal to or higher than a predetermined level, the value of the steering torque falls below the predetermined level. It is safe because the operation of the electric power steering device can be limited until the steering when detected is completed.

Further, the operation of the shut-off means is conditioned on the fact that if the value of the steering torque at the time of detecting the abnormality is below a predetermined level, the value of the steering torque exceeds the predetermined level. It is safe because the operation of the electric power steering device can be limited until the steering when detected is completed.

Further, since the operation of the breaking means is on condition that when the current value of the electric motor at the time of detecting the abnormality is equal to or higher than a predetermined level, it is below the predetermined level, the abnormality is detected. The operation of the electric power steering device can be limited until the steering is completed when the steering is performed, which is safe.

Further, the operation of the shutoff means is conditioned on the fact that if the value of the steering torque at the time of detecting the abnormality is below a predetermined level, each of the values exceeds the predetermined level. It is safe because the operation of the electric power steering device can be limited until the steering when detected is completed.

Further, since the operation of the shut-off means is on condition that if the vehicle speed at the time of detecting the abnormality is equal to or higher than the first predetermined level, then it falls below the predetermined level, the abnormality is detected. It is safe because the operation of the electric power steering device can be limited until the vehicle speed is reduced safely when it is driven.

Further, the operation of the cutoff means controls the torque to zero while the vehicle speed at the time of detecting the abnormality is equal to or higher than the second predetermined level while the vehicle speed is equal to or higher than the second predetermined level. Therefore, when an abnormality is detected, it is safe even when traveling at high speed.

Further, since the operation of the shut-off means is on condition that the engine rotation speed at the time of detecting the abnormality is equal to or higher than a predetermined level, it is thereafter lower than the predetermined level, so that the abnormality is detected. The operation of the electric power steering device can be limited until the end of the steering, which is safe.

Further, the operation of the shut-off means is conditioned on the turning off of the engine ignition key after the abnormality is detected. Therefore, when the abnormality is detected, the electric power steering device is activated before the steering is completed. Can be limited and safe.

Further, while the torque control is continued after the abnormality is detected, the first warning lamp notifies that fact, and when the electric power steering device is shut off, the second warning lamp notifies. Therefore, the driver can accurately know the operating state of the electric power steering device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an electric power steering device according to a first embodiment of the present invention.

FIG. 2 is a control block diagram according to the first embodiment.

FIG. 3 is an explanatory waveform diagram of a position sensor abnormality state included in FIG. 2;

FIG. 4 is a flowchart illustrating the operation of FIG.

FIG. 5 is a partial detailed flowchart of FIG.

FIG. 6 is a flowchart of processing when abnormality is detected in the second embodiment.

FIG. 7 is a flowchart of processing when abnormality is detected in the third embodiment.

FIG. 8 is a flowchart of processing at the time of abnormality detection according to the fourth embodiment.

FIG. 9 is a flowchart in which the flow of processing at the time of abnormality detection according to the fourth embodiment is changed.

FIG. 10 is a flowchart of processing when abnormality is detected in the fifth embodiment.

FIG. 11 is a flowchart of processing when abnormality is detected in the sixth embodiment.

FIG. 12 is a waveform diagram of a motor current at a normal time for explaining the operation of the seventh embodiment.

FIG. 13 is a waveform diagram for explaining the operation of the seventh embodiment when the motor current is abnormal.

FIG. 14 is a flowchart of processing when abnormality is detected in the seventh embodiment.

FIG. 15 is a configuration diagram of a conventional electric power steering device.

FIG. 16 is a control block diagram of a conventional electric power steering device.

[Explanation of symbols]

1 Steering wheel, 3 Torque sensor, 1
3 vehicle speed sensor, 20 motor, 21 brushless motor, 22 motor position sensor, 30 controller, 39 relay, 40 abnormality determination means, 100 electric power steering device.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B62D 137: 00 H02P 6/02 371D F term (reference) 3D032 CC08 CC33 CC39 CC40 DA15 DA23 DA49 DA63 DA64 DB02 DB11 DC01 DC02 DC08 DC09 DC33 DC34 DD01 DD10 DD17 DE08 DE09 EB11 EB12 EC23 EC24 GG01 3D033 CA03 CA13 CA16 CA20 CA21 CA31 5H560 AA08 BB04 DA07 DA10 DA19 DC02 DC03 DC12 EB01 JJ02 XA05 XB09

Claims (18)

[Claims] 1. A torque control procedure for controlling torque of an electric motor connected to a steering shaft to assist a steering force applied to the steering shaft, a zero torque control procedure for controlling torque of the electric motor to zero, and the electric motor. Position detection procedure for detecting the rotation angle position of the, the amplitude value of the position signal output by the position detection procedure fluctuates according to the rotation angle position of the electric motor, based on the presence or absence of a case lower than a predetermined value. An abnormality detection procedure for detecting an abnormality in the position detection procedure, and after the abnormality in the position detection procedure is detected by the abnormality detection procedure, the amplitude value of the position signal is set to a predetermined value in accordance with a change in the rotational angle position of the electric motor. At a rotational angle position above a level, the torque control procedure is executed to output a torque to assist the steering force, and the amplitude value of the position signal is below a predetermined level. The control method of the abnormality detection time used in an electric power steering apparatus characterized by comprising abnormality control procedure for the output torque to zero by executing the zero torque control procedure at a rotational angular position of the motor made. 2. A motor which is connected to a steering shaft so as to be able to transmit power to give an auxiliary force, a position sensor which detects a rotational angle position of the electric motor, a drive circuit which controls a current flowing through the electric motor, and a driver operates the steering shaft. A torque sensor that detects the steering force applied to the steering shaft by steering the steering shaft, determines the driving direction and magnitude of the auxiliary force of the electric motor from the torque signal of the torque sensor, and generates the auxiliary force in the drive circuit. A controller that outputs a current command signal, the electric motor, the position sensor, the drive circuit, the torque sensor, and the operation of the controller is monitored, and the torque sensor is normal, and any of the other is abnormal. When detected, the content of this abnormality is analyzed to determine whether the direction of the auxiliary force output by the electric motor may not match the direction of the steering force. The electric power steering apparatus characterized by comprising a first abnormality determining means for to output the current command signal to the controller when it is determined that no said fear outputs the auxiliary force from said electric motor. 3. A motor that is connected to the steering shaft so as to be able to transmit power and applies an auxiliary force to the steering shaft, a position sensor that detects a rotational angle position of the electric motor, a drive circuit that controls a current flowing through the electric motor, and a driver A torque sensor for detecting a steering force generated on the steering shaft by steering the steering shaft, a driving direction and a magnitude of an auxiliary force of the electric motor are determined from a torque signal of the torque sensor, and the auxiliary force is supplied to the drive circuit. A controller that outputs a current command signal that generates a force, the electric motor, the position sensor, the drive circuit, the torque sensor, and the operation of the controller is monitored, the torque sensor is normal, the electric motor, the If an abnormality is detected in any of the position sensor, the drive circuit, and the controller, the content of the abnormality is analyzed and the abnormality is detected. If it is determined that the abnormality does not occur depending on the angular position and there is no risk that the direction of the assisting force does not coincide with the direction of the steering force, a current command signal according to the rotational angular position of the electric motor is sent to the controller. The electric power steering apparatus is provided with a second abnormality determining means for outputting the electric power from the electric motor to output the auxiliary force according to the rotational angle position of the electric motor. 4. The electric motor is a multi-phase AC electric motor having three or more phases, and the first or second abnormality determination means is one of multi-phase windings of the electric motor or one of power supply lines to the electric motor. The electric wire according to claim 2 or 3, wherein the wire breakage generated in the book is determined to be an abnormality in which the direction of the assisting force output from the electric motor does not become inconsistent with the direction of the steering force. Power steering device. 5. The drive circuit outputs a three-phase alternating current, and the first or second abnormality determination means is provided with the three-phase alternating current.
3. The output voltage drop of one phase of the phase AC output is determined to be an abnormality in which the direction of the auxiliary force output by the electric motor does not become inconsistent with the direction of the steering force. Alternatively, the electric power steering device according to item 3. 6. The first or second abnormality determination means,
The abnormality occurring in the position sensor is determined to be an abnormality in which the direction of the assisting force output by the electric motor does not become inconsistent with the direction of the steering force. Electric power steering device. 7. The electric power steering apparatus according to claim 4, wherein the abnormality content of the controller is such that current cannot be output to one phase of the electric motor. 8. The controller determines that the abnormality detected by the first or second abnormality determination means is an abnormality that is unlikely to cause a reversal in the direction of the assisting force output by the electric motor. 4. The electric power steering apparatus according to claim 2, further comprising a cutoff unit that cuts off power supply to the electric motor when a predetermined condition is satisfied after the output of the command signal is continued. 9. The electric power according to claim 8, wherein the predetermined condition is a lapse of a predetermined time after the abnormality is detected by the first or second abnormality determining means. Steering device. 10. When the steering force when the first or second abnormality determination means detects an abnormality is equal to or more than a predetermined value set in advance, the steering force changes to the predetermined value or less. 9. The electric power steering device according to claim 8, wherein the predetermined condition is satisfied. 11. When the steering force when the first or second abnormality determination means detects an abnormality is equal to or less than a predetermined value set in advance, the steering force changes to the predetermined value or more. 9. The electric power steering device according to claim 8, wherein the predetermined condition is satisfied. 12. When the current of the electric motor at the time when the first or second abnormality determination means detects an abnormality is equal to or more than a predetermined value set in advance, the current changes to the predetermined value or less. 9. The electric power steering device according to claim 8, wherein the predetermined condition is satisfied. 13. When the current of the electric motor at the time when the first or second abnormality determining means detects an abnormality is equal to or less than a predetermined value set in advance, the current changes to the predetermined value or more. 9. The electric power steering device according to claim 8, wherein the predetermined condition is satisfied. 14. A vehicle speed sensor for detecting a vehicle speed, wherein the vehicle speed when the vehicle speed when the first or second abnormality determination means detects an abnormality is equal to or more than a first predetermined value set in advance, 9. The electric power steering apparatus according to claim 8, wherein: the predetermined condition is that the value of the electric power steering ratio changes to the first predetermined value or less. 15. A vehicle speed sensor for detecting a vehicle speed, wherein the vehicle speed when the vehicle speed when the first or second abnormality determination means detects an abnormality is equal to or more than a second predetermined value set in advance, 15. The electric power steering apparatus according to claim 14, wherein the torque of the electric motor is controlled to zero while is greater than or equal to the second predetermined value. 16. The electric motor according to claim 8, further comprising a rotation speed sensor for detecting an engine rotation speed, wherein the predetermined condition is that the engine rotation speed is below a predetermined value. Power steering device. 17. When the first or second abnormality determination means does not detect the abnormality, the circuit operation is stopped after a predetermined time has elapsed since the ignition key switch was turned off. 9. The electric power steering apparatus according to claim 8, wherein the predetermined condition is that the state of the ignition key switch is turned off when the first or second abnormality determination means detects an abnormality. 18. A voice, a lamp, a buzzer, or until the operation of the electric power steering device is stopped after the predetermined condition is satisfied after the first or second abnormality determination means detects an abnormality, The electric power steering apparatus according to any one of claims 2 to 17, further comprising warning means for warning the driver by displaying an image.