JP2001122139A - Electric power steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate a phase of detected steering torque and to accurately cope with abnormality of a phase compensation circuit for this phase compensation in an electric power steering device applying assist force in accordance with steering torque. SOLUTION: A main torque voltage signal MTV representing a steering torque detected by a torque sensor device 50 is subjected to phase compensation by a main phase compensation circuit 61a and it is fed to a CPU 65 as a main phase compensation signal MPV. A sub phase compensation circuit 61b connected in parallel with the main phase compensation circuit 61a and identically constituted also feed a sub phase compensation signal SPV based upon the main torque voltage signal MTV to the CPU 65. The CPU 65 controls an electric motor 14 in accordance with the main phase compensation signal MPV for assisting control of steering operation, and it also detects abnormality of the main or sub phase compensation circuits 61a or 61b by comparing both phase compensation signals MPV and SPV.

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 for a vehicle which assists a steering operation of a steering wheel by rotating an electric motor.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Utility Model Registration Publication No. 2
As shown in Japanese Patent No. 524450, a torque sensor device for detecting a steering torque is provided, and the rotation of the electric motor is controlled in accordance with the steering torque detected by the torque sensor device, so that the steering operation of the steering wheel is performed by the electric motor. 2. Description of the Related Art An electric power steering apparatus for a vehicle that assists by rotation of a vehicle is well known. In this electric power steering device, two main and sub sensors are provided as a torque sensor device, and the output of the main sensor is used as a detected steering torque for controlling the electric motor. When the deviation of each output value is large, the abnormality of the torque sensor device is determined, and the control of the electric motor is stopped.

[0003]

According to the above-mentioned conventional device, an abnormality of the torque sensor device can be detected. However, in controlling the electric motor for assisting the steering operation of the steering wheel, in order to prevent the steering system from becoming unstable in a specific frequency region due to vibration, the detected steering torque is not directly used. Instead, it is desirable to use after compensating the phase of the detected steering torque, and when the detected steering torque is phase-compensated as described above, even if an abnormality occurs in the means for performing the same phase compensation, the above-described conventional method is used. The device cannot handle it.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to address the above-mentioned problem, and an object of the present invention is to perform phase compensation on a detected steering torque so that a steering system becomes unstable in a specific frequency region due to vibration. It is an object of the present invention to provide an electric power steering apparatus capable of preventing the occurrence of a phase error and appropriately coping with an abnormality occurring in a means for performing the phase compensation.

In order to achieve the above object, the structural features of the present invention include an electric motor for applying an assist force to a turning operation of a steering wheel, and a steering torque detected to represent the detected steering torque. A torque sensor device that outputs a detection signal, a main phase compensator that compensates for the phase of the steering torque represented by the detection signal from the torque sensor device, and an electric motor that responds to the steering torque whose phase is compensated by the main phase compensator. In an electric power steering device for a vehicle having a motor control means for controlling rotation of a motor, a sub phase for compensating a phase of a steering torque represented by a detection signal from a torque sensor device with characteristics similar to those of the main phase compensation means. A deviation between the steering torque whose phase is compensated by the compensating means and the main phase compensating means and the steering torque whose phase is compensated by the sub-phase compensating means is predetermined. In providing the abnormality detecting means for detecting an abnormality of the main phase compensation means or by-phase compensation means on condition that is greater than.

According to the present invention, the main phase compensating means compensates for the phase of the steering torque detected by the torque sensor device, and the motor control means converts the phase of the steering torque to the compensated steering torque. Since the rotation of the electric motor is controlled accordingly, the assist control is accurately performed for the turning operation of the steering wheel in a state where the steering system is kept stable over all frequency ranges. Further, a sub-phase compensator for compensating for the phase of the steering torque detected by the torque sensor device with the same characteristics as the main phase compensator is provided, and the abnormality detector includes the steering torque whose phase has been compensated for by the main phase compensator. The abnormality of the main phase compensator is detected on the condition that the deviation from the steering torque whose phase has been compensated by the sub-phase compensator is larger than a predetermined value. An abnormality is detected, and the abnormality can be properly dealt with.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows an electric power steering apparatus for a vehicle according to the embodiment.

In this electric power steering apparatus, the turning operation of the steering handle 11 is performed by the rack and pinion mechanism 1.
Steering shaft 1 transmitting to left and right front wheels FW1 and FW2 via
3 is provided with the electric motor 14 assembled. The electric motor 14 is constituted by a DC motor, and provides an assisting force to the turning operation of the steering handle 11 in accordance with its rotation. The rotation is transmitted to the steering shaft 13 via the speed reduction mechanism 15. It has become so.

An electric control unit 20 is electrically connected to the electric motor 14, and a vehicle speed sensor 21 and a sensor unit SU are connected to the electric control unit 20. The vehicle speed sensor 21 detects the vehicle speed V and supplies a detection signal indicating the vehicle speed V to the electric control device 20. Sensor unit SU
Is assembled to the steering shaft 13 and constitutes a part of a sensor device 50 described later.

As shown in FIG. 2, the electric control device 20
An electronic control circuit unit ECU for controlling the rotation of the electric motor 14 is provided, and a battery voltage from a battery 25 is supplied to the unit ECU via a relay switch 26 and an ignition switch 27. . The relay switch 26 is normally in an on state, and is controlled by a fail detector (not shown) for detecting a failure of the electric power steering device.
It is turned off when a failure is detected. The ignition switch 27 is turned on by the driver when the engine is started.

The electronic control circuit unit ECU includes a drive circuit 30 and power supply circuits 41 and 42. Drive circuit 3
0 indicates that a drive current flows through the electric motor 14,
And the like, and a bridge circuit having switching elements 31 to 34 as four sides. One of a pair of opposite diagonal positions of the bridge circuit is connected to the relay switch 26 via a shunt resistor 35, and the other of the same pair of diagonal positions is grounded via a shunt resistor 36. Both terminals of the electric motor 14 are connected to the other diagonal position of the bridge circuit.

A power supply voltage for the electronic control circuit unit ECU based on the battery voltage is supplied to the power supply circuits 41 and 42 from the ignition switch 27 and the relay switch 26 via diodes 43 and 44 having their cathodes connected in common. It has become. The power supply circuit 41 reduces the battery voltage and outputs a power supply voltage that is a predetermined constant voltage (for example, 8 V). The voltage is supplied to the torque sensor device 50. The power supply circuit 42 also reduces the battery voltage and outputs a power supply voltage that is a predetermined constant voltage (for example, 5 V). The power supply circuit 42 includes a main phase compensation circuit 61a, a sub phase compensation circuit 61b, a current detection circuit 62, Voltage detection circuit 6
3, the input interface circuit 64, the CPU 65, the memory device 66, the output interface circuit 67, and the drive control circuit 68, respectively. The current detection circuit 62, the voltage detection circuit 63, the output interface circuit 6
The power supply voltage supplied to the power supply circuits 41 and 42 via the diodes 43 and 44 is directly supplied to the drive interface 7 and the drive control circuit 68, and the power supply voltage is supplied to the output interface circuit 67 and the drive control circuit 68. The voltage is supplied directly, and the output interface circuit 67 is connected to the current detection circuit 62 and the voltage detection circuit 63.
Alternatively, the power supply voltage may be supplied via the drive control circuit 68.

The torque sensor device 50 is operated by a power supply voltage supplied from a power supply circuit 41. As shown in FIG. 3, an oscillation circuit 52, a current amplification circuit 53a, an inversion current amplification circuit 53b, a sampling pulse generation circuit 54,
It includes main and sub differential amplifier circuits 55a and 55b, main and sub sample and hold circuits 56a and 56b, and main and sub output circuits 57a and 57b.

The oscillation circuit 52 includes, as shown in FIG.
A sine wave signal that vibrates up and down with a predetermined period and a predetermined amplitude around the reference potential is output. The current amplification circuit 53a current-amplifies the sine wave signal and outputs the amplified signal. The inversion current amplifier circuit 53b inverts the phase of the sine wave signal and amplifies and outputs the current (see FIG. 4B). Based on the sine wave signal from the oscillating circuit 52, the sampling pulse generation circuit 54 uses a rectangular wave pulse train signal substantially synchronized with the peak position value of the sine wave signal as shown in FIG. Sub sample and hold circuits 56a, 5
6b.

Between the outputs of the current amplifier circuits 53a and 53b, both ends of serially connected coils L1 and L2 of the same inductance constituting the sensor unit SU are connected. The coils L1 and L2 are respectively attached to both ends of an elastic torsion member such as a torsion bar which forms a part of the steering shaft 13, and generate a steering torque (steering reaction force) TM acting on the steering handle 11 and the steering shaft 13. Accordingly, each of the inductances of the coils L1 and L2 is configured to change in opposite directions. That is, from the connection point of the two coils L1 and L2, the steering torque T
A sine wave signal whose amplitude changes in accordance with the torque TM including the direction of M is extracted. The resistances r1, r2 and r2 are connected to both ends of the coils L1 and L2 connected in series.
A series circuit composed of r3 and a series circuit composed of resistors r4, r5, and r6 are connected in parallel. Resistance r3, r6
Are constituted by potentiometers, and reference potentials are respectively taken out from the resistors r3 and r6.

The main differential amplifier circuit 55a includes coils L1, L
A signal taken out from the connection point 2 and a reference potential from the resistor r3 are input, and a difference signal between them is output. The sub differential amplifier circuit 55b receives the signal extracted from the connection point between the coils L1 and L2 and the reference potential from the resistor r6, and outputs a difference signal between them. These main and sub differential amplifier circuits 55
The outputs of a and 55b are connected to the main and sub-sample and hold circuits 56a and 56b, respectively.

The main and sub sample-and-hold circuits 56a, 56
6b is a unidirectional semiconductor switching element for inputting voltage signals from the main and sub differential amplifier circuits 55a and 55b,
A capacitor connected to the output side of the switching element for storing a voltage; and a resistor for discharging the voltage stored in the capacitor with an extremely large time constant. The main and sub differential amplifier circuits 55a and 55b are synchronized with the sampling pulse supplied to the control terminal.
Sample and hold the voltage signals from Note that these main and sub sample-and-hold circuits 56a, 56a
6b also has a low-pass filter function using the capacitor and the resistor.

The main output circuit 57a includes coils L1, L2,
A main sensor circuit for detecting the steering torque TM is formed together with the resistors r1, r2, r3, the main differential amplifier circuit 55a and the main sample hold circuit 56a, and amplifies a voltage signal from the main sample hold circuit 56a. And outputs a main torque voltage signal MTV representing the steering torque TM. The sub output circuit 57b includes coils L1 and L2, resistors r4 and r
5, r6, the sub differential amplifier circuit 55b and the sub sample and hold circuit 56b together constitute a sub sensor circuit for detecting the steering torque TM, and amplify the voltage signal from the sub sample and hold circuit 56b to obtain the steering torque. An auxiliary torque voltage signal STV representing TM is output. The main torque voltage signal MTV and the sub torque voltage signal STV have a lower limit (for example, 2.5 V) around a reference potential (for example, 2.5 V).
1.0v) and an upper limit value (for example, 4.0v).

Returning to the description of FIG. 2, the main phase compensation circuit 61a compensates the phase of the main torque voltage signal MTV (detected steering torque TM) in order to prevent the steering system from becoming unstable due to vibration. The same signal M
A predetermined frequency range included in the TV (for example, about 10 to 30H
z) to advance the phase of the frequency component to obtain the main phase compensation signal MP
Output as V. The sub phase compensation circuit 61b also compensates for the phase of the main torque voltage signal MTV. The signal SPV is output. These main and sub phase compensation circuits 61
a, 61b are the steering torques TM avoiding signal transmission delay.
And an analog circuit for transmitting the main and sub torque voltage signals MTV and STV representing the following in real time.

The current detection circuit 62 is connected to both ends of the shunt resistor 36 and outputs a detection signal representing the drive current Im flowing to the electric motor 14 based on the voltage across the resistor 36. The voltage detection circuit 63 is connected to both ends of the electric motor 14 and outputs a detection signal representing a terminal voltage Vm of the motor 14. The input interface circuit 64 receives the main and sub torque voltage signals MT from the torque sensor device 50.
V, STV, main and sub phase compensation signals MPV, SPV from main and sub phase compensation circuits 61a, 61b, vehicle speed sensor 2
1, a detection signal representing the vehicle speed V from the current detection circuit 62, a detection signal representing the drive current Im from the current detection circuit 62, and the voltage detection circuit 6
3, a detection signal representing the terminal voltage Vm is input. The input interface circuit 64 has a built-in A / D converter and the like, and converts the input analog detection signal into a digital signal, as necessary, and supplies it to the CPU 65.

The CPU 65 repeatedly executes the programs shown in the flowcharts of FIGS. 5 and 6 at predetermined short intervals to control the electric motor 14 and deal with various abnormalities. The memory device 66 includes a ROM and a RAM (including a non-volatile memory area), and stores the program and variables necessary for executing the program. The output interface circuit 67 outputs to the drive control circuit 68 a control signal corresponding to the command current value I * to be supplied to the electric motor 14 calculated by executing the program. The drive control circuit 68 controls on / off of the switching elements 31 to 34 in the drive circuit 30 according to the control signal.

Next, the operation of the embodiment configured as described above will be described. The power supply voltage from the battery 25 is supplied to various circuits by turning on the ignition switch 27,
The various circuits start operating. In the CPU 65,
The program in FIG. 5 is started to be repeatedly executed every predetermined short time. At this time, the relay switch 26 is also turned on, and the relay switch 26 supplies the power supply voltage from the battery 25 to the drive circuit 30 and other circuits.

The execution of the program of FIG.
In step 102, it is determined whether the sensor abnormality flag SFF or the phase compensation abnormality flag PFF is "1". The sensor abnormality flag SFF indicates an abnormality of the torque sensor device 50 by “1”, and indicates that the abnormality has not occurred by “0”.
0 ”. Phase compensation abnormality flag PFF
Indicates that the main phase compensating circuit 61a or the sub phase compensating circuit 61b is abnormal by "1", and that the abnormalities do not occur by "0", and is initially set to "0". .

First, a case where no abnormality occurs in the torque sensor device 50, the main phase compensation circuit 61a and the sub phase compensation circuit 61b will be described. In this case, since both the sensor abnormality flag SFF and the phase compensation abnormality flag PFF are "0", "NO" is determined in the step 102, and the abnormality detection routine is executed in the step 104.

The execution of the abnormality detection routine is started in step 200 of FIG. 6, and in step 202, the absolute value | MTV−STV | of the deviation between the main torque voltage signal MTV and the sub torque voltage signal STV is determined in advance. Small predetermined value ΔT
It is determined whether it is V or more. Torque sensor device 50
If there is no abnormality in the main torque voltage signal MTV
And the auxiliary torque voltage signal STV should be equal,
In step 202, “NO” is determined, and
At step 4, the count value TCT is cleared to "0" and the program proceeds to step 214. This count value TCT
Is for determining an abnormality of the torque sensor device 50.

In step 214, the absolute value | MP of the deviation between the main phase compensation signal MPV and the sub phase compensation signal SPV
It is determined whether or not V-SPV | is equal to or greater than a predetermined small predetermined value ΔPV. If no abnormality occurs in the main phase compensation circuit 61a and the sub phase compensation circuit 61b, since both circuits 61a and 61b have the same configuration and input the same signal, the main phase compensation signal MPV and the sub phase compensation signal SPV are Should be equal. Therefore, in this case, step 2
At 14, “NO” is determined, and at step 216, the count value PCT is cleared to “0”, and at step 226, the execution of the abnormality detection routine is terminated. This count value PCT is for determining abnormality of the main phase compensation circuit 61a or the sub phase compensation circuit 61b.

Returning to the description of FIG. 5, after executing the abnormality detection routine of step 104, step 10
At 6, it is determined whether the sensor abnormality flag SFF or the phase compensation abnormality flag PFF is "1". In this case as well, as in the case of the step 102, the step 10
In step 6, “NO” is determined, and the program is executed in step 10.
Proceed to 8 or later.

In step 108, based on the drive current Im of the electric motor 14 from the current detection circuit 62 and the terminal voltage Vm of the electric motor 14 from the voltage detection circuit 63, the electric motor 14 14 is calculated.

[0029]

Ω = (Vm−Rm · Im) / K

The above equation (1) is an approximate expression for calculating the rotational angular velocity of a DC motor that does not consider the inductance (the inductance is small and can usually be ignored), and K and Rm are constants determined by the motor. Since the electric motor 14 and the steering wheel 11 rotate integrally, the rotational angular speed ω is equal to the steering speed of the steering wheel 11, and the same rotational angular speed ω is hereinafter used as the steering speed.

Next, at step 110, a command current value I * for the electric motor 14 is calculated in order to cause the electric motor 14 to generate an assist force according to the steering state of the steering wheel 11. The command current value I * is calculated by adding each compensation value including the inertia compensation value, the steering wheel return compensation value, and the damping compensation value to the basic assist value.

The basic assist value is a basic control value for giving an assist force to the turning operation of the steering wheel 11, and is provided for each of a plurality of vehicle speed ranges and includes a steering torque TM.
Is calculated based on the steering torque TM and the vehicle speed V represented by the main phase compensation signal MPV, with reference to a conversion table for converting. As shown in FIG. 7, the basic assist value increases as the steering torque TM increases and decreases as the vehicle speed V increases.

The inertia compensation value is determined by the turning operation of the steering handle 11 (particularly, the turning operation of the steering handle 11 at the start of turning).
To compensate for the inertial force of the electric motor 14. The inertia compensation value is determined based on a differential value obtained by differentiating the steering torque TM and the vehicle speed V. The steering wheel return compensation value is for compensating that the steering wheel 11 is quickly returned to the neutral position when the steering wheel 11 is turned back, and based on the steering speed ω and the vehicle speed V, the steering speed ω increases. Therefore, it is calculated to a value that increases and decreases as the vehicle speed V increases. The damping compensation value is for compensating for imparting resistance to the turning operation of the steering wheel 11, and acts in a direction opposite to the steering speed ω based on the steering speed ω and the vehicle speed V. , The absolute value increases as the absolute value | ω | of the steering speed ω increases, and the absolute value increases as the vehicle speed V increases.

After the processing of step 110, step 1
At 14, the difference between the calculated command current value I * and the drive current Im is calculated, and a control signal corresponding to the difference is output to the drive control circuit 68 via the output interface circuit 67. The drive control circuit 68 controls the switching elements 31 to 34 of the drive circuit 30 so that the drive current Im of the electric motor 14 becomes equal to the command current value I *. Accordingly, the electric motor 14 rotates, and this rotation is transmitted to the steering shaft 13 via the speed reduction mechanism 15 and the rotation is transmitted to the steering shaft 13.
Is rotated with an assist force corresponding to the command current value I *, so that the turning operation of the steering wheel 11 is assisted with an assist force corresponding to the steering torque TM. Also, in this case,
Since the vehicle speed V, the inertia compensation, the steering wheel return compensation, and the damping compensation are also considered, the steering feeling of the driver is improved.

Next, when an abnormality occurs in the torque sensor device 50, the main torque voltage signal MT
Absolute value | MTV of deviation between V and auxiliary torque voltage signal STV
The case where −STV | is equal to or greater than the predetermined value ΔTV will be described. In this case, "YES" is determined in step 202 of the abnormality detection routine of FIG. 6, "1" is added to the count value TCT in step 206, and in step 208, the count value TCT is set to a predetermined time (for example, , 30ms)
Is determined to be equal to or greater than a predetermined value TCTo corresponding to

If the count value TCT has not reached the predetermined value TCTo if the time has not passed since the absolute value | MTV-STV | of the deviation became equal to or greater than the predetermined value ΔTV, “NO” is determined in step 208. And the program proceeds to step 214. Absolute value of the deviation | MT
When V-STV | has exceeded the predetermined value ΔTV for the predetermined time or more and the count value TCT has reached the predetermined value TCTo, “YES” is determined in step 208 and the sensor abnormality flag SFF is determined in step 210. Is set to “1”. Then, at step 212, the fact that an abnormality has occurred in the torque sensor device 50 is written together with the time of occurrence into a non-volatile memory area provided in the memory device 66, and a warning lamp (not shown) is turned on to notify the driver of the abnormality. Notify occurrence.

Next, when an abnormality occurs in the main phase compensation circuit 61a or the sub phase compensation circuit 61b, the main phase compensation signal MPV and the sub phase compensation signal SPV output from the main and sub phase compensation circuits 61a and 61b respectively are used. Absolute value of deviation | MP
The case where V-SPV | is equal to or larger than the predetermined value ΔPV will be described. In this case, “YES” is determined in step 214 of the abnormality detection routine of FIG. 6, and “1” is added to the count value PCT in step 218.
, The count value PCT is set to a predetermined time (for example, 30 m
It is determined whether or not the value is equal to or greater than a predetermined value PCTo corresponding to s).

If the count value PCT has not reached the predetermined value PCTo if the time has not passed since the absolute value | MPV-SPV | of the deviation became equal to or larger than the predetermined value ΔPV, “NO” is determined in step 220. Is determined, and the execution of this routine is terminated in step 226. When the absolute value | MPV-SPV | of the deviation has become equal to or more than the predetermined value ΔPV for the predetermined time or more and the count value PCT reaches the predetermined value PCTo, in step 220, “YE
S ”, and in step 222, the phase compensation abnormality flag PFF is set to“ 1 ”. Then, step 224
The main phase compensation circuit 61a or the sub phase compensation circuit 61b
The occurrence of an abnormality in the memory device 66 together with the time of occurrence.
In addition to writing to a non-volatile memory area provided in the inside, a warning lamp (not shown) or the like is turned on to notify the driver of the occurrence of an abnormality.

As described above, when the sensor abnormality flag SFF or the phase compensation abnormality flag PFF is set to "1",
"YES" in steps 102 and 106 of FIG.
As a result, the abnormality detection routine of step 104 is not executed, and the command current value I * is set to “0” by the processing of step 112. As a result, also in the drive control of the electric motor 14 in step 114, the drive current Im of the motor 14 is controlled to “0”, so that the assist control for the turning operation of the steering wheel 11 is also stopped. As a result, the rotation control of the electric motor 14, that is, the assist control for the turning operation of the steering wheel 11, is not performed by the main phase compensation signal MPV that does not accurately represent the steering torque TM.

As can be understood from the above description of operation, the main torque voltage signal MTV representing the steering torque TM detected by the torque sensor device 50 is phase-compensated by the main phase compensation circuit 61a, and the in-phase compensated steering torque TM Is supplied to the CPU 65 via the input interface circuit 64, and the CPU 65 calculates the command current value I * using the steering torque TM that has been phase-compensated by the processing in step 110. 1
Since the rotation of the electric motor 14 is controlled in accordance with the same command current value I * by the processing in step 14, the steering system does not become unstable in a specific frequency range, and the steering handle 11
The assist control by the electric motor 14 is accurately performed over the entire frequency range for the turning operation of.

The abnormality of the main phase compensating circuit 61a for compensating the phase of the steering torque TM is determined in steps 214-2.
24, is detected using the sub phase compensation signal SPV from the sub phase compensation circuit 61b configured identically to the main phase compensation circuit 61a.
Since the rotation control of the electric motor 14, that is, the assist control for the turning operation of the steering wheel 11, is stopped by the processes of 2, 106, and 112, even if an abnormality occurs in the main phase compensation circuit 61a, the abnormality is not affected. Appropriate processing is performed.

Further, in the above embodiment, the main torque voltage signal MTV and the sub torque voltage signal STV are output from the torque sensor device 50, so that step 202 is performed.
Through 212, the main or sub phase compensation circuit 61a,
61b, independently of the abnormality detection.
Is detected and recorded, the abnormality of the torque sensor device 50 and the main or sub phase compensation circuits 61a, 61
Abnormality of b can be clearly distinguished, and subsequent correct measures can be expected.

In the abnormality detection of the torque sensor device 50, the absolute value | MTV-STV | of the deviation between the main torque voltage signal MTV and the sub torque voltage signal STV continues for a predetermined time or more by the processing of steps 202 to 208. Only when this is done, the abnormality is determined. In the abnormality detection of the main or sub phase compensation circuits 61a and 61b, the absolute value | MPV-SP of the deviation between the main phase compensation signal MPV and the sub phase compensation signal SPV is obtained by the processing of steps 214 to 220.
An abnormality is determined only when V | has continued for a predetermined time or more. Thus, the absolute value of the deviation | MTV
If the abnormality of -STV | or | MPV-SPV | is temporary due to noise, a sudden reason, or the like, the torque sensor device 50 or the main or sub phase compensation circuit 61a,
The abnormality of 61b is not finally determined, and the abnormality is accurately determined. The torque sensor device 50
The main torque voltage signal MTV and the main phase compensation signal MPV each have an out-of-specified value (predetermined lower limit) in addition to or independently of the abnormality detection of the above-described embodiment. Abnormality detection may be employed in which the condition for abnormality determination is that the value (a value not between the value and the upper limit) continues for a predetermined time or more.

Further, the processing of steps 214 to 220 of the abnormality detection routine of FIG. 6 of the above embodiment can be modified to the processing of steps 214a to 220a and 214b to 220b of FIG. Step 214 of this modification
The processing of steps a to 220a and the processing of steps 214b to 220b are performed in steps 214 to 22 of the above-described embodiment, respectively.
The operation contents are the same as those of the processing of 0 except that the variables and constants are different. That is, PCT1 and PCT2 are count values for judging abnormality of the main or sub phase compensation circuits 61a and 61b, and are predetermined predetermined values ΔPV1,
ΔPV2, PCT1o, PCT2o are ΔPV1> ΔP
V2> 0, 0 <PCT1o <PCT2o.
According to this, when the absolute value | MPV-SPV | of the deviation between the main phase compensation signal MPV and the sub phase compensation signal SPV is large, this state continues only for a short time and the main or sub phase compensation circuits 61a and 61b operate. An abnormality is determined. When the absolute value | MPV-SPV | of the deviation is small,
If this state does not continue for a long time, the main or sub phase compensation circuit 6
No abnormality is determined for 1a and 61b. As a result, according to the determination according to this modification, the main or sub phase compensation circuit 61
The abnormalities of a and 61b are more accurately determined.

Note that the abnormality determination method according to the modified example is
Even if the predetermined values PCT1o and PCT2o are set equal, the count value PCT is set at steps 218a and 218b.
1 and PCT2 are also realized by changing the value added to each. This means that the value added to the count value PCT1 in step 218a is
By setting to a value larger than the value added to the count value PCT2, the count value PCT1 quickly reaches the predetermined value PCT1o (= PCT2o), and the count value PCT2 slowly reaches the predetermined value PCT2o (= PCT1o). Because it reaches. Further, the abnormality determination method according to this modified example can be used as an abnormality determination method for the torque sensor device 50.

Further, the processing of step 214 of the abnormality detection routine of FIG.
It can also be modified as in the process of H.244. In step 230, the absolute value | MPV-SPV | of the difference between the main phase compensation signal MPV and the sub phase compensation signal SPV is calculated, and the calculated absolute value | MPV-SPV | is set as the deviation value ΔV. Then, in step 232, the deviation value ΔV is added to the integrated value VA, and in step 234, “1” is added to a variable i for counting the number of times of integration.
At 6, it is determined whether or not the variable i is greater than or equal to a predetermined value p.
The integrated value VA and the variable i are initially set to “0”.

Until the deviation value ΔV is integrated p times, “NO” is determined in step 236, and step 226 is performed.
Ends the execution of the abnormality detection routine. On the other hand, when the deviation value ΔV is integrated p times, the variable i becomes p, and “YES” is determined in the step 236, and the step 238 is performed.
The following processing is executed. In step 238,
The past q integrated values VA (1) to VA (q) are updated.
That is, the oldest integrated value VA (1) becomes the next oldest integrated value V
A (2), the next oldest integrated value VA (2) is updated to the next oldest integrated value VA (3), and the oldest integrated value is sequentially updated to the next oldest integrated value. Is done. And
The newest integrated value VA (q) is updated to the integrated value VA calculated by the process of step 232. After the processing in the step 238, in a step 240, the integrated value VA
Is cleared to “0”, and the variable i is cleared to “0”.

Next, in step 242, the total value VT of the updated past q integrated values VA (1) to VA (q) is calculated. In step 244, when the total value VT is equal to or greater than the predetermined value VTo, It is determined whether or not there is. If the total value VT is less than the predetermined value VTo, "NO" is determined in step 244, the count value PCT is cleared to "0" in step 216, and the program is executed in the same manner as in the above embodiment. The process proceeds to 220 and thereafter. If the total value VT is equal to or greater than the predetermined value VTo, “YES” is determined in step 244, and the count value PCT is set to “1” in step 218.
Is added, and the program proceeds to the processing after step 220 similar to the above embodiment.

Therefore, according to this modification, the deviation ΔV between the main phase compensation signal MPV and the sub phase compensation signal SPV
(= | MPV-SPV |) is calculated for each predetermined short time, and an integrated value VA obtained by integrating the calculated deviation values ΔV by p is calculated. Further, a total value VT of the past q integrated values VA (1) to VA (q) is calculated, and only when the total value VT is equal to or more than the predetermined value VTo continuously for PCTo times or more, the main or The sub phase compensation circuit 61a,
The abnormality of 61b is determined. As a result, according to the determination according to this modification, the main or sub phase compensation circuits 61a and 61b
Will be more accurately determined. It should be noted that the processing of steps 214a and 214b in FIG. 8 according to the modified example can be replaced by the processing of steps 230 to 244.

Further, in the above-described embodiment, an analog main phase compensation circuit 61a is employed as a means for implementing the phase compensation of the main torque voltage signal MTV representing the steering torque TM in consideration of a time delay. However, in a system in which the time delay is not so problematic, a phase compensating circuit having a digital type hardware circuit configuration for realizing phase compensation of the same characteristic may be used instead of the main phase compensating circuit 61a. The phase compensation process having the same characteristic may be performed by software by the program process described above.

In the above embodiment, in order to accurately and quickly detect an abnormality in the main phase compensation circuit 61a,
Sub-phase compensation circuit 61 identical to main phase compensation circuit 61a
b was used. However, when the time delay, the comparison error, and the like do not matter, even when the analog main phase compensation circuit 61a as in the above embodiment is used,
Instead of the analog-type sub phase compensating circuit 61b, a digital-type hardware compensating circuit as described above may be used, or the phase compensating process may be performed by software by the CPU 65 program processing. Good. When a digital-type hardware phase compensation circuit is used in place of the main phase compensation circuit 61a, or when the phase compensation processing is performed by software using the program processing of the CPU 65, the sub-phase compensation circuit 61b is also adapted to this. It is preferable to use a digital-type phase compensation circuit having a hard circuit configuration, or to perform the phase compensation processing by software by a program processing of the CPU 65.

In the above embodiment, only the steering torque TM represented by the main phase compensation signal MPV from the main phase compensation circuit 61a is used for the rotation control of the electric motor 14, but the main phase compensation signal MPV is not used. The rotation of the electric motor 14 may be controlled using an average value of the steering torque TM represented by the MPV and the steering torque TM represented by the sub phase compensation signal SPV from the sub phase compensation circuit 61b. In this case, in step 110 in FIG. 5, the steering torque TM represented by the main phase compensation signal MPV from the main phase compensation circuit 61a and the steering torque TM represented by the sub phase compensation signal SPV from the sub phase compensation circuit 61b. TM
The command current value I * may be calculated using the average value of. As described above, controlling the electric motor 14 using the average value of the steering torques TM represented by the main phase compensation signal MPV and the sub phase compensation signal SPV has the same phase compensation characteristics as described above. Is applied to the case where the main phase compensation circuit 61a and the sub phase compensation circuit 61b having different forms are used.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of an electric power steering device according to an embodiment of the present invention.

FIG. 2 is an overall block diagram of the electric control device of FIG.

FIG. 3 is a detailed circuit diagram of the torque sensor device of FIG. 2;

4A and 4B are torque sensor units SU of FIG.
FIG. 4 is a waveform chart showing a sine wave signal added to (a), and (C) is a time chart showing a sampling pulse.

FIG. 5 is a flowchart of a program executed by a CPU in FIG. 2;

FIG. 6 is a flowchart showing details of an abnormality detection routine of FIG. 5;

FIG. 7 is a graph showing a relationship between a steering torque and a basic assist value.

FIG. 8 is a flowchart according to a modification in which a part of the abnormality detection routine in FIG. 6 is modified.

FIG. 9 is a flowchart according to another modification in which a part of the abnormality detection routine of FIG. 6 is modified.

[Explanation of symbols]

FW1, FW2: left and right front wheels, SU: sensor unit, E
CU: control circuit unit, 11: steering wheel, 13:
Steering shaft, 14: electric motor, 20: electric control device, 21
... Vehicle speed sensor, 30 ... Drive circuit, 50 ... Torque sensor device, 61a ... Main phase compensation circuit, 61b ... Sub phase compensation circuit, 65 ... CPU, 68 ... Drive control circuit.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D032 CC08 CC28 CC35 DA09 DA15 DA23 DA64 DA65 DC03 DC04 DC09 DC17 DC22 DC29 DC33 DC34 DC40 DD17 DE09 EA01 EB11 EC23 GG01 3D033 CA03 CA13 CA16 CA19 CA20 CA21 CA24 CA31 CA32 CA33

Claims (1)

[Claims] An electric motor for applying an assist force to a turning operation of a steering wheel; a torque sensor device for detecting a steering torque and outputting a detection signal representing the detected steering torque; Main phase compensating means for compensating for the phase of the steering torque represented by the detection signal of the above, and motor control means for controlling the rotation of the electric motor according to the steering torque whose phase has been compensated by the main phase compensating means. An electric power steering device for a vehicle, comprising: a sub phase compensator for compensating a phase of a steering torque represented by a detection signal from the torque sensor device with characteristics similar to those of the main phase compensator; and the main phase compensator. The deviation between the phase-compensated steering torque and the phase-compensated steering torque by the sub-phase compensator is greater than a predetermined value. Electric power steering apparatus for a vehicle, characterized by comprising an abnormality detector for detecting an abnormality of the main phase compensation means or by-phase compensation means to the condition.