JP2006051881A - Controlling device for electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controlling device for an electric power steering device which prevents a torque assist from being completely stopped under a slightly irregular state of a signal amplifying means. <P>SOLUTION: This controlling device for the electric power steering device assist-controls by imparting an assist force by a motor to a steering system. The controlling device is provided with an irregularity detecting means which detects irregularity of the signal amplifying means and a direction storage means which detects and stores the direction of a torque signal when an irregularity is detected by the irregularity detecting means. Then, a normal assist, an assist temporary stop, a returning and an assist stop of the assist control are controlled from the detection by the irregularity detecting means and the direction of the torque signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for an electric power steering device that applies a steering assist force by a motor to a steering system of an automobile or a vehicle, and particularly detects an abnormal state of a signal amplification means of a torque system, a current system, or a voltage system and detects a torque signal. The present invention relates to a control device for an electric power steering device in which assist control is returned based on direction and size.

  An electric power steering device normally used in a vehicle detects steering steering torque input by a steering wheel with a torque sensor, obtains auxiliary torque corresponding to the steering steering torque by a motor, and urges the steering device to perform steering. The steering force of the steering device input by the person is reduced.

  Here, the general configuration of the electric power steering apparatus will be described with reference to FIG. 6. The column shaft 2 of the steering handle 1 is connected to the steering wheel via the reduction gear 3, the universal joints 4 a and 4 b, and the pinion rack mechanism 5. Coupled to the tie rod 6. The column shaft 2 is provided with a torque sensor 10 that detects the steering torque of the steering handle 1, and a motor 20 that assists the steering force of the steering handle 1 is coupled to the column shaft 2 via the reduction gear 3. ing. The control unit 30 that controls the power steering device is supplied with electric power from the battery 14 via the ignition key 11 and the relay 13, and the control unit 30 is detected by the steering torque T detected by the torque sensor 10 and the vehicle speed sensor 12. The steering assist command value I of the assist command is calculated based on the vehicle speed V, and the current supplied to the motor 20 is controlled based on the calculated steering assist command value I.

  The control unit 30 is mainly composed of a CPU (including an MPU). FIG. 7 shows general functions executed by a program inside the CPU. For example, the phase compensator 31 does not indicate a phase compensator as independent hardware, but indicates a phase compensation function executed by the CPU.

  The function and operation of the control unit 30 will be described. The steering torque T detected and input by the torque sensor 10 is phase-compensated by the phase compensator 31 in order to improve the stability of the steering system, and the phase-compensated steering torque. TA is input to the steering assist command value calculator 32. The vehicle speed V detected by the vehicle speed sensor 12 is also input to the steering assist command value calculator 32. The steering assist command value calculator 32 determines a steering assist command value I that is a control target value of the current supplied to the motor 20 based on the input steering torque TA and vehicle speed V. The steering assist command value I is input to the subtractor 30A, and is also input to the feedforward differential compensator 34 for increasing the response speed. The deviation (Ii) of the subtractor 30A is input to the proportional calculator 35. At the same time, it is input to an integration calculator 36 for improving the characteristics of the feedback system. Together with the output of the differential compensator 34, the outputs of the proportional calculator 35 and the integral calculator 36 are also added to the adder 30B, and the current control value E, which is the addition result of the adder 30B, is used as a motor drive signal as a motor drive circuit. 37. The current i of the motor 20 is detected by the motor current detection circuit 38 and fed back to the subtractor 30A.

  In such an electric power steering apparatus, an amplifier for amplifying a torque sensor signal (steering torque T) is provided, and if the torque is continuously applied when an abnormality occurs in the amplifier, the driver inputs In some cases, an assist torque unrelated to the steering torque is applied to the steering device, which hinders the steering by the steering person. There are various situations in which the output value of the amplifier appears to be abnormal. There may be a serious failure state in which the torque assist by the motor must be stopped immediately, or there may be a torque assist such as an abnormality in the amplifier itself. There is a case where the abnormal state is so slight that it does not hinder the steering of the steering device even if it is not completely stopped. When the electric power steering device stops torque assist, in the case of a vehicle that requires a large steering torque, such as a large vehicle or a truck, there is a possibility that the steering by the driver may be immediately disabled. For this reason, there is a problem in completely stopping the torque assist when the abnormality of the output value of the amplifier is detected.

  Therefore, when an abnormality occurs in the output value of the amplifier that amplifies the conventional torque sensor signal, the torque assist is temporarily stopped, and when the output value returns to the normal state, the assist state is returned to detect the abnormality of the output value. When the number of times exceeds a predetermined value, a configuration is adopted in which it is determined as a failure state and torque assist is completely stopped (for example, Patent Document 1).

  That is, as shown in FIG. 8, the device disclosed in Patent Document 1 includes a torque sensor 101 that detects the steering force of a vehicle, and a control that controls the output of auxiliary torque by inputting an output signal from the torque sensor 101. The control device 102 generates a torque command 103 for amplifying the torque sensor signal from the torque sensor 101, and a current command value for controlling the output of the auxiliary torque by the input from the torque sensor 101 and the torque amplifier 103. ON / OFF of the control unit 104 for controlling, the drive circuit 106 for inputting a current command value from the control unit 104 and outputting the drive current, the electric motor 105 driven by the drive current, and the motor drive power from the battery 107 And a power relay 108.

  In such a configuration, the operation is as shown in the flowchart of FIG. That is, the estimated output of the torque amplifier 103 is set to (TS−2.5) × Gain → “GTS” from the output voltage TS of the torque sensor 101 (where Gain is the amplification factor of the torque amplifier 103), and the theoretical calculation value of the amplified voltage Is set (step S101), and it is determined whether or not the calculated value “GTS” is larger than the measurement upper limit 5V (step S102). If the calculated value “GTS” is larger than 5V, the calculated value “GTS” is set to 5V (step S103). After the setting or when the calculated value “GTS” is less than or equal to the measurement upper limit value 5V in step S102, it is determined whether or not the calculated value “GTS” is smaller than the measurement lower limit value 0V (step S104). If it is smaller, the calculated value “GTS” is set to 0 V (step S105). After the setting or when the calculated value “GTS” is greater than or equal to the measurement lower limit value 0 V in step S104, a deviation ΔVTS between the amplified voltage VTS that is the actual output of the torque amplifier 103 and the calculated value GTS is obtained (step S106). Then, it is determined whether or not the deviation ΔVTS is larger than a predetermined value ERR (step S107).

  As a result of the determination, if the deviation ΔVTS is equal to or smaller than the predetermined value ERR, it is determined whether or not the calculated value “GTS” is larger than the threshold TH2 (step S108), and if it is equal to or smaller than the threshold TH2, the calculated value “ It is determined whether or not “GTS” is smaller than the threshold TH3 (step S109). If the calculated value “GTS” is larger than the threshold TH2 in step S108, the process ends when the calculated value “GTS” is smaller than the threshold TH3 in step S109. If the calculated value “GTS” is lower than the threshold TH2, the threshold TH3 is reached. In the above case, the counter FAILcnt is cleared to zero (step S110), and OFFflag2 used for determination is cleared to zero (step S111).

On the other hand, if the deviation ΔVTS is larger than the predetermined value ERR in step S107, the counter FAILcnt is incremented (step S112), and it is determined whether the counter FAILcnt is larger than the predetermined value FT1 (step S113). If it is greater than the value FT1, the flag is set to FAILflag to stop completely (step S115). If it is less than or equal to the predetermined value FT1, it is further determined whether or not the counter FAILcnt is greater than the predetermined value FT2 (step S114). If the value is larger than the value FT2, OFFflag2 is set and paused (step S116), and then the routine is terminated.
JP 2001-171538 A

  In the control disclosed in Patent Document 1 described above, for example, when the amplification state of the torque amplifier 103 becomes abnormal when the steering wheel is steered in one direction, the output value of the torque amplifier 103 is increased with the steering of the steering wheel. When an abnormality is detected, the assist by the motor is temporarily stopped, the manual input increases, and the output of the torque sensor signal increases. As a result, when the output value of the torque amplifier 103 returns to the normal range and torque assist is resumed, the torque sensor signal decreases again, and the output value of the torque amplifier 103 appears abnormal. In this way, the circulation of torque sensor signal abnormality detection → assist limit (assist temporary stop) → limit release → torque sensor signal abnormality detection →... Is repeated in a short time.

  As described above, when an abnormality occurs such that the output value of the torque amplifier 103 repeats the circulation between the abnormal region and the normal region, the return counter immediately exceeds the allowable number of returns and is determined to be a failure state. Even so, there is a problem that the electric power steering apparatus immediately stops the torque assist.

  The present invention has been made under the circumstances as described above, and the object of the present invention is that the fail safe function malfunctions due to an abnormality in the signal amplifying means such as the torque amplifying means generated during the steering of the steering wheel, and the torque assist is performed. It is an object of the present invention to provide a control device for an electric power steering device that can efficiently prevent a situation where the vehicle completely stops.

  The present invention relates to a control device for an electric power steering apparatus configured to perform assist control by applying an assist force from a motor to a steering system, and the above object of the present invention is to detect abnormality detecting signal abnormality. And a direction storage means for detecting and storing the direction of the torque signal when an abnormality is detected by the abnormality detection means, and the assist based on the detection of the abnormality detection means and the direction of the torque signal This is achieved by controlling the normal assist, assist pause, return and assist stop of the control.

  The object of the present invention is to control the assist pause when the abnormality detection means detects an abnormality of the signal amplification means, and to always wait for a return, or to detect the abnormality detection means and First control is performed by controlling normal assist, assist temporary stop, return and assist stop of the assist control based on the direction and magnitude of the torque signal, or when the abnormality detection means detects an abnormality of the signal amplification means. The assist temporary stop control is performed until a predetermined time, and further, the assist stop control is performed when the second predetermined time has elapsed, or the signal amplifying means is at least one of a torque system, a current system or a voltage system. This can be achieved more effectively.

  The present invention also relates to a control device for an electric power steering device configured to perform assist control by applying an assist force from a motor to a steering system, and the above object of the present invention is to provide a torque signal corresponding to the steering torque. A torque detecting means for outputting; a torque amplifying means for amplifying the torque signal; a current command value calculating means for outputting a current command value based on the torque signal and the vehicle speed; and a motor for steering assist based on the current command value. The torque amplifying unit detects a degree of abnormality of the torque amplifying unit based on an output signal of the driving amplifying unit and the torque amplifying unit, and inputs a control signal to the current command value calculating unit. Depending on the degree of abnormality of the means, the drive of the motor is controlled by normal assist, assist temporary stop, return and assist stop It is achieved by providing a normally detecting means.

  The object of the present invention is that the torque amplifying means comprises a first amplifying means and a second amplifying means having an amplification factor different from that of the first amplifying means, and the abnormality detecting means is the second amplifying means. Proportional amplifying means, a comparing means for comparing each output of the proportional amplifying means and the first amplifying means, a counter for counting time based on a comparison result of the comparing means, and a return counter, The stop / return control unit that determines the normal assist, the assist temporary stop, the return, and the assist stop based on the comparison result and each count value of the counter and the return counter, and determines the return from the abnormal state to the normal state This is achieved more effectively by using the direction of the torque signal as a reference.

  According to the present invention, there is provided an abnormality detecting means for detecting an abnormality of a torque system, current system or voltage system signal amplifying means, and the normal assist of the assist control based on the detection of the abnormality detecting means and the direction and magnitude of the torque signal. Since the control of assist pause, return, and assist stop is controlled, it is ensured that the fail safe function malfunctions due to an abnormality in the signal amplification means that occurs during the steering of the steering wheel, and the torque assist stops completely. Can be prevented. As a result, an efficient and economical control device for an electric power steering device can be realized.

  The present invention relates to a control device for an electric power steering device that performs assist control by applying an assist force from a motor to a steering system, and detects an abnormality in a signal amplification means of a torque system, a current system, or a voltage system. An abnormality detecting means is provided for controlling the normal assist, temporary stop, return and stop of the assist control based on the detection of the abnormality detecting means and the direction and magnitude of the torque signal. When the abnormality detecting unit detects an abnormality of the signal amplifying unit, the assist temporary stop control is performed until the first predetermined time, and further, the assist stop control is performed when the second predetermined time has elapsed. If the second predetermined time has not elapsed, the normal assist is continued after returning. Alternatively, it always waits for return without providing the second predetermined time.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment of a control device for an electric power steering apparatus according to the present invention. A torque sensor signal (steering torque) T from a torque sensor 41 as torque detecting means is sent to a torque amplifier 50 as an amplifying means. Entered. The torque amplifier 50 includes a first amplifier 51 having an amplification factor G1 and a second amplifier 52 having an amplification factor G2 (<G1). The torque sensor signal T1 amplified by the first amplifier 51 is a comparator in the abnormality detecting means 60. 62, the torque sensor signal T2 input to the phase compensator 43 and amplified by the second amplifier 52 is input to the proportionality amplifier 61 of the amplification factor K in the abnormality detection means 60, and the phase compensator. 43. The output (= K · T2) of the proportional amplifier 61 is input to the comparator 62, and the comparison result of the comparator 62 is a counter for measuring time (# 1, # 2, not shown) and a return counter for counting the number of return times. The output value (time) of the counter and the output value (number of times) of the return counter are respectively input to the stop / return control unit 65, and the control signal CS1 as a result of the processing is input to the current command value calculator. 44. The comparison result of the comparator 62 is also input to the stop / return control unit 65. The memory 45 stores a current command value I corresponding to the steering torque TA with the vehicle speed V as a parameter, and is used for calculation of the current command value I of the current command value calculator 44.

  The abnormality detection means 60 is provided together with the torque direction storage means in the abnormality determination processing means for performing the abnormality determination processing of FIG.

  The current command value calculator 44 receives the steering torque TA phase-compensated from the phase compensator 43 and the vehicle speed V from the vehicle speed sensor 42, and the angular velocity ω estimated by the motor angular velocity estimator 47. . The current command value I calculated by the current command value calculator 44 is input to the subtractor 46. The motor current i of the motor 40 is detected by a motor current detection circuit 80 having a built-in abnormality detection means (not shown), and the detected motor current i is input to the subtractor 46 and fed back, and a motor angular velocity estimation unit. The control signal CS2 input to 47 and output when an abnormality is detected is input to the current command value calculator 44 via the adder 48. Further, the motor voltage v of the motor 40 is detected by a motor voltage detection circuit 81 having a built-in abnormality detection means (not shown), and the detected motor voltage v is input to the motor angular velocity estimation unit 47 to detect an abnormality. The control signal CS3 that is sometimes output is input to the current command value calculator 44 via the adder 48. The deviation (I-i) obtained by the subtractor 46 is input to the proportional-integral calculator 71 in the drive control means 70, and the current control value E as the proportional-integral output is input to the PWM controller 72 for PWM processing. The PWM controller 72 outputs a PWM control signal E ′ as a current control value, and the inverter 73 drives the assisting motor 40.

The following equation (1) is established among the amplification factor G1 of the first amplifier 51, the amplification factor G2 of the second amplifier 52, and the amplification factor K of the proportional amplifier 61.

G1 = G2 × K (1)

The relationship of the above expression (1) is similarly applied to the motor current detection means 80 and the motor voltage detection means 81 that incorporate the abnormality detection means.

  Further, the abnormality detection means 60 detects the abnormality by sampling the torque sensor signals T1 and T2 from the torque amplifier 50 every predetermined time (for example, 1 msec to 2 msec) during the process of the abnormality determination routine. The output of the proportional amplifier 61 obtained by amplifying the torque sensor signal T2 with the amplification factor K and the torque sensor signal T1 amplified by the first amplifier 51 are input to the comparator 62, and the comparator 62 compares the magnitudes of both input signals. Calculate (difference). The counter that counts the output of the comparator 62 measures the duration of the abnormal state based on the comparison result of the comparator 62, and the return counter is the abnormal state based on the comparison result of the comparator 62. The normal state continuation time (number of times) when returning from normal to normal is measured. The output of the counter and the return counter is input to the stop / return control unit 65 together with the comparison result of the comparator 62. The stop / return control unit 65 performs normal assist, assist temporary stop, and return based on the comparison result and the output of the counter and return counter. Further, the control signal CS1 is output by determining the assist stop.

  In the present invention, the direction and the magnitude of the torque signal are used as the criteria for determining the normal state.

  In such a configuration, an example of the operation will be described with reference to the flowchart (abnormality determination processing means) in FIG.

  In the normal state, the torque sensor signal T from the torque sensor 41 is amplified by the first amplifier 51 and the second amplifier 52, and the amplified torque sensor signals T1 and T2 are input to the phase compensator 43 to be phase compensated. By inputting the steering torque TA to the current command value calculator 44, a current command value with the vehicle speed V as a parameter is read from the memory 45, and a current command value I is generated. A deviation from the motor current i is calculated by the subtractor 46 for the current command value I, the deviation is input to the proportional-integral calculator 71, and a current control value E as the proportional-integral output is input to the PWM controller 72. PWM processing is performed, a PWM control signal E ′ as a current control value is output from the PWM controller 72, and the motor 40 is driven by the inverter 73.

  Here, the torque sensor signal T1 from the first amplifier 51 and the torque sensor signal T2 from the second amplifier 52 are input to the abnormality detection means 60, and the abnormality detection means 60 is in accordance with the abnormality determination routine shown in FIG. 50 normal / abnormal states are determined, and assist pause, return, and assist stop are controlled according to the determination result. In FIG. 1, the motor current detection circuit 80 and the motor voltage detection circuit 81 perform similar abnormality detection, but only the abnormality of the torque amplifier 50 will be described here.

  The comparator 62 always obtains the difference between the torque sensor signal T1 from the first amplifier 51 and the output of the proportional amplifier 61, that is, the signal T2 · K, and stops the difference (comparison result = | T1−T2 · K |). This is input to the return control unit 65. Then, the stop / return control unit 65 determines whether or not the difference is larger than a predetermined value ε (for example, 0.5 V) (step S1), and determines that the difference is larger than the predetermined value ε as abnormal, When the difference is equal to or smaller than the predetermined value ε, it is determined as normal.

  If it is determined normal in step S1, it is determined whether or not the assist is temporarily stopped based on the output of the return counter (step S2). Exit the routine.

If it is determined in step S2 that the assist is temporarily stopped, the counter (# 1) starts to be increased (step S3), the count value of the counter (# 1) exceeds a predetermined time t1 (for example, 50 msec), and torque It is determined whether or not the direction of the signal is reversed (T _FLG · T2 <0) based on the direction storage means (step S4). If either or both of the conditions are not satisfied, a return waiting state in which nothing is performed is entered, and the abnormality determination routine is terminated. If both conditions are satisfied in step S4, the return counter is incremented (step S5), and the stop / return control unit 65 instructs the current command value calculator 44 to return assist with the control signal CS1. (Step S6), then, a state transition to the normal assist state is instructed (Step S7), and the abnormality determination routine is terminated.

On the other hand, if the difference between the torque sensor signal T1 and the signal T2 · K exceeds the predetermined value ε in step S1, it is determined as abnormal, the counter (# 2) is increased (step S10), and the counter (# It is determined whether or not the count value of 2) has exceeded a predetermined value t2 (for example, 15 msec) (step S11), and if it is equal to or less than the predetermined value t2, the abnormality determination routine is temporarily ended as being determined. If the count value of the counter (# 2) exceeds the predetermined value t2 in step S11, it is determined that there is a failure and the torque direction is stored in the torque direction storage means (T _FLG = T2) (step S11A). Then, the stop / return control unit 65 instructs the current command value calculator 44 to temporarily stop the assist using the control signal CS1 (step S12), and further instructs the transition to the assist temporarily stopped state (step S13). Then, it is determined whether or not the count value of the return counter has exceeded a predetermined value t3 (for example, “2”) (step S14). If the count value exceeds the predetermined value t3, a transition to the assist stop state is instructed (step S14). S15), the abnormality determination routine is terminated. If the count value of the return counter is equal to or smaller than the predetermined value t3 in step S14, the abnormality determination routine is terminated as it is, and a failure recovery is awaited in the assist temporarily stopped state.

  As described above, it is possible to reliably prevent a situation in which the fail-safe function malfunctions due to an abnormality of the torque amplifier 50 that occurs during steering of the steering wheel and the torque assist is completely stopped. The same applies to the motor current detection circuit 80 and the motor voltage detection circuit 81.

Here, in a state where the control device of the electric power steering device is operating normally, the output value (torque sensor signal T 2 · K) of the proportional amplifier 61 inputted to the comparator 62 in the abnormality detecting means 60 and the first The output value (torque sensor signal T1) of one amplifier 51 is the same. Therefore, if the output value of the proportional amplifier 61 is a parameter in the horizontal axis (x-axis) direction and the output value of the first amplifier 51 is a parameter in the vertical axis (y-axis) direction, the following equation (2) is established, It is displayed as a characteristic line RC in FIG.

y = x (2)

When the characteristic line RC of the above equation (2) is set as a reference value, a region (white part) shifted up and down from the characteristic line RC by the predetermined value ε in step S1 is a normal region, and other regions are It becomes an abnormal area (shaded area). The greater the difference between the output value (T1) of the first amplifier 51 to the comparator 62 and the output value (K · T2) of the proportional amplifier 61, the greater the distance from the characteristic line RC, and the greater the distance, the torque amplifier. 50 indicates a deviation from the normal state. The measurement point A in FIG. 3 indicates that the inputs T1 and K · T2 of the comparator 62 are not equally different and exist on the characteristic line RC in the normal region. Further, the measurement point B indicates that there is a difference between the inputs T1 and K · T2 of the comparator 62, and that a slight abnormality has occurred, but is within the normal region. There is a difference equal to or greater than a predetermined value ε between the inputs T1 and K · T2, indicating that it is within the abnormal region.

  FIG. 4 shows the operations of steps S1, S10, and S11 described above. While the assist operation is being performed at point A in the normal region, a difference occurs in the inputs T1 and K · T2 of the comparator 62 due to a failure or the like. When moving to the point A ′ in the region (step S1), the counter (# 2) is started to be increased (step S10), and when the time t2 or more has elapsed, the stop / return control unit 65 causes the assist temporary stop by the control signal CS1. An instruction is given (steps S11 and S12). In this operation, for example, an abnormality occurs in the torque amplifier 50 when the steering handle is steered, and the output value of the first amplifier 51 becomes very small, whereas the value obtained by multiplying the signal of the second amplifier 52 by K is unchanged. This is the case. In this case, when the second amplifier 52 is operating normally, the measurement point may momentarily enter the abnormal region due to external vibration or the like. Therefore, the continuation of the time during which the measurement point is in the abnormal region is predetermined. If it returns to the normal region in less than the time (t2), the torque assist is continued as a normal state, and if it is in the abnormal region for a predetermined time (t2) or longer, the torque assist is temporarily stopped as a possibility of failure. State. The predetermined time t2 is desirably a time sufficient for detecting an abnormality in the amplification state of the torque amplifier 50, for example, about 10 msec to 50 msec, but the predetermined time t2 is not limited to this. Alternatively, the predetermined time t2 may not be provided, and the apparatus may be configured to always wait for the return while the assist is temporarily stopped.

  When the assist temporary stop state is entered, the assist torque decreases, and the steering torque increases in order to keep the steering wheel at the same angle as before the failure with the assist torque decreasing. When the steering torque increases from the position A ′ to the position A ″ in FIG. 5, since it is in the normal region, it returns (resumes assist). Also, when the assist torque increases and the steering torque decreases from A ″ to A ′, for example. In the prior art, there has been a problem of such abnormality detection → normal recovery → abnormality detection .... In the present invention, the direction of the torque signal is stored in the torque direction storage means, and the torque direction is normally set. This problem is solved by adding to the condition for determining the return to the assist, that is, the steering torque increases in the assist pause state, and even when the position A ″ in FIG. ), The torque does not return to normal, but the torque D in the normal area is detected in the opposite direction to A when the abnormality is detected (see FIGS. 3 and 4), and the normal area has a predetermined time (t1) or more. When present in connection with, so that the electric power steering apparatus returns to the normal assist state.

  In this example, the predetermined time t1 for returning to the normal state is set to 50 msec, but is not limited to this time, and may be a time sufficient to confirm that the output of the torque amplifier 50 is normal. It ’s fine.

  As described above, when the driver once returns the handle and passes through the torque neutrality and the normal region continues with the torque in the direction opposite to that at the time of occurrence of the abnormality, the driver returns to the normal state. At this time, a condition that “torque is not more than a predetermined value” (for example, a predetermined value F in FIG. 5) may be added to the normal return condition. Further, depending on the failure mode of the amplifier, there are cases where the power supply value and the ground fault value are output and the intermediate value is not output. Therefore, it is more effective to restore the torque under the condition that the torque is equal to or less than a predetermined value and the reverse torque.

  On the other hand, when the electric power steering apparatus that has returned to the normal state in this manner is repeatedly brought into the assist pause state again and again, there is a high possibility that the torque amplifier 50 has failed. It is also possible to determine that a failure has occurred when the number of times the motor has returned to the normal assist state exceeds a predetermined number (for example, two times), and stop the torque assist completely. The number of returns is counted by the return counter.

  In this example, the torque amplifier 50 includes the first amplifier 51 and the second amplifier 52. However, the present invention is not limited to this, and the configuration in which the second amplifier 52 does not exist (amplification factor G2 = The present invention can also be applied to the torque amplifier 1).

  In this embodiment, the abnormality determination of the torque amplifier 50 with respect to the torque sensor 41 is performed. However, the present invention is not limited to this. For example, in the abnormality determination of the motor current detection unit and the motor voltage detection unit, etc. The same can be applied.

  According to the present invention, the abnormality detection means for detecting abnormality of the signal amplification means such as the torque system is provided, and the assist control is normally assisted, paused, and resumed based on the detection of the abnormality detection means and the direction and magnitude of the torque signal. Therefore, it is possible to reliably prevent a situation in which the fail-safe function malfunctions due to a slight abnormality of the signal amplification means that occurs during the steering of the steering wheel, and the torque assist is completely stopped. It can be applied to high performance electric power steering devices.

It is a block block diagram which shows one Example of this invention. It is a flowchart which shows the operation example of this invention. It is a state diagram for demonstrating the operation example of this invention. It is a state diagram for demonstrating the operation example of this invention. It is a state diagram for demonstrating the operation example of this invention. It is a block diagram which shows the outline of a general electric power steering apparatus. It is a block diagram which shows an example of a control unit. It is a block diagram which shows an example of the failure determination apparatus of the conventional torque signal amplification means. It is a flowchart which shows the operation example of the conventional failure determination apparatus.

Explanation of symbols

1 Steering handle 10, 41 Torque sensor 12, 42 Vehicle speed sensor 20, 40 Motor 30 Control unit 43 Phase compensator 44 Current command value calculator 47 Motor angular velocity estimation unit 50 Torque amplifier 60 Abnormality detection means 61 Proportional amplifier 62 Comparator 65 Stop / return control unit 70 Drive control means 71 Proportional integral computing unit 72 PWM controller 73 Inverter 80 Motor current detection circuit 81 incorporating abnormality detection means Motor voltage detection circuit incorporating abnormality detection means

Claims (7)

In a control device for an electric power steering apparatus configured to perform assist control by applying an assist force from a motor to a steering system, an abnormality detection unit that detects an abnormality of a signal amplification unit, and an abnormality is detected by the abnormality detection unit Direction storage means for detecting and storing the direction of the torque signal at the time, and based on the detection of the abnormality detection means and the direction of the torque signal, normal assistance of the assist control, assist pause, return, and A control device for an electric power steering device, characterized in that assist stop is controlled. 2. The control device for an electric power steering apparatus according to claim 1, wherein when the abnormality detection unit detects an abnormality of the signal amplification unit, the control of the assist temporary stop is performed and the apparatus is always on standby for return. 3. 2. The electric power steering according to claim 1, wherein normal assist, assist temporary stop, return, and assist stop of the assist control are controlled based on detection of the abnormality detection means and direction and magnitude of the torque signal. Control device for the device. When the abnormality detecting means detects an abnormality of the signal amplifying means, the assist temporary stop control is performed until the first predetermined time, and the assist stop control is performed when the second predetermined time has passed. The control device for an electric power steering apparatus according to claim 1. The control device for an electric power steering apparatus according to any one of claims 1 to 4, wherein the signal amplifying means is at least one of a torque system, a current system, and a voltage system. Torque detecting means for outputting a torque signal corresponding to steering torque; torque amplifying means for amplifying the torque signal; current command value calculating means for outputting a current command value based on the torque signal and vehicle speed; and the current command A drive control means for controlling a motor that performs steering assist according to the value; and an abnormality degree of the torque amplification means based on an output signal of the torque amplification means; and a control signal for the current command value calculation means. An electric power steering system comprising: an abnormality detecting means for controlling driving of the motor by normal assist, assist temporary stop, return and assist stop according to the degree of abnormality of the torque amplifying means by inputting Control device for the device. The torque amplifying means comprises a first amplifying means and a second amplifying means having an amplification factor different from that of the first amplifying means, and the abnormality detecting means amplifies the output of the second amplifying means; Comparison means for comparing the outputs of the proportional amplification means and the first amplification means, a counter and a return counter for counting time based on the comparison result of the comparison means, the comparison result, and the counter and the return counter. It consists of a stop / return control unit that determines the normal assist, assist temporary stop, return and assist stop based on each count value, and uses the direction of the torque signal as a criterion for returning from the abnormal state to the normal state The control device for the electric power steering device according to claim 6.

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