JP2002087304A - Electric power steering control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering control device capable of preventing detection errors of motor current detection value abnormality due to back electromotive force of a motor for preventing deterioration in steering feeling. SOLUTION: This device is provided with a target determining means to preliminarily determine a target value of a current to be sent to the motor, a motor current detecting means to detect the motor current, a motor current control means provided with a first motor control process to closed loop-control the motor current sent to the motor in accordance with the target value and the detected motor current, and a second motor control process to open loop- control the motor current to be sent to the motor in accordance with the target value, and an abnormality detection means to determine if the detected motor current has abnormality or not, and switch control to the motor current to the second motor control process when it is determined to have abnormality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a motor current in an open loop when a failure occurs in a current detection circuit of a motor for generating a steering assist force in a steering mechanism, and preventing an abnormal current from flowing to the motor. The present invention relates to an electric power steering control device for preventing electric power steering.

[0002]

2. Description of the Related Art In an electric power steering control device,
The motor current target value is compared with the motor current detection value that is actually flowing to the motor, and feedback control is performed so that the two values match.If the motor current detection means fails, abnormal motor current Therefore, it is necessary to detect abnormalities promptly and take measures. In the electric power steering control device described in WO 98/33270, when an abnormality of the current detection circuit is detected, the control is shifted to open loop control to prevent an abnormal current from flowing to the motor. Hereinafter, a control method of the electric power steering control device will be described.

FIG. 15 shows, for example, WO 98/33270.
FIG. 1 is a configuration diagram of a conventional electric power steering control device disclosed in Japanese Unexamined Patent Application Publication No. 2000-205,073. A steering shaft 2 is connected to the handle 1, and a rack & pinion 5 is connected thereto via a speed reducer. The steering shaft 2 is provided with a torque sensor 3 for detecting a steering torque. Also,
A motor 8 for generating an assist torque is connected to the speed reducer 4. The motor 8 is connected to a controller 9 that generates a control current based on a vehicle speed detection value from the vehicle speed sensor 7 and a torque detection value from the torque sensor 3.

FIG. 16 is a block diagram for explaining the operation of the controller 9 of the electric power steering apparatus.
The controller 9 is a relay 2 for shutting off the power of the motor 8.
1. A relay driving circuit 22 for driving a relay 21;
A motor drive circuit 23 for driving the motor, a motor current detection circuit 24 for detecting a current flowing to the motor 8 through the motor drive circuit 23, a motor current detection value by the motor current detection circuit 24, a torque detection value by the torque sensor 3, and a vehicle speed sensor 7 The microcomputer 26 controls the relay 21 and the motor 8 based on the detected vehicle speed. Note that the microcomputer 26 has a first motor control process and a second motor control process as means for controlling the motor current, and switches based on the result of abnormality detection of the current detection circuit.

FIG. 17 is a block diagram showing a first motor control process in the microcomputer 26. In this block diagram, the target current determining means 41
The motor current target value IMT is determined from the steering torque and the vehicle speed based on the characteristic diagram as described above.

The motor control means 42 has a motor current target value I
The motor current flowing to the motor 8 is controlled based on the deviation between the MT and the motor current detection value IMS detected by the motor current detection circuit 24 so as to become the motor current target value IMT.

FIG. 19 is a block diagram showing the operation of the motor current control means 42. The proportional term 51 performs a proportional operation on a deviation ΔIM between the motor current target value IMT and the motor current detection value IMS. The integral term 52 performs an integral operation on the deviation ΔIM. The motor driving means 53 drives the motor 8 by applying a voltage corresponding to the sum VMT of the calculation results of the proportional term 51 and the integral term 52 to the motor 8.

FIG. 20 is a block diagram showing a second motor control process in the microcomputer 26. The second motor control process is an open-loop control in which the input of the motor current detection circuit 24 is eliminated from the first motor control process shown in FIG. Then, as shown in FIG. 21, the motor current control means 42 obtains a motor voltage target value VMT which is a value obtained by multiplying the motor current target value IMT by the predetermined value Ra set by the constant setting unit 54, and obtains the motor voltage target value VMT. The motor driving means 53 drives the motor 8 in accordance with. Here, the predetermined value Ra is a resistance value of the motor 8. That is, by applying the motor voltage target value VTM, which is a value obtained by multiplying the motor current target value IMT and the motor resistance value Ra, to the motor 8, it is possible to control the motor 8 to flow the motor current target value IMT.

Next, the operation of the microcomputer 26 will be described with reference to the flowchart of FIG. After activation of the electric power steering control device, the relay 21 is turned on in step 101, the steering torque detected from the torque sensor 3 is input in step 102, and the vehicle speed is input from the vehicle speed sensor 7 in step 103.

In step 104, the motor current target value IMT is determined from the steering torque and the vehicle speed. In step 105, the motor current detection value IMS is detected from the motor current detection circuit 24. In step 106, the abnormality of the motor current detection value IMS is determined. judge. If the result of the determination is normal, the flow branches to step 108 in step 107 to perform first motor control processing. On the other hand, if abnormal, the process branches to step 109 in step 107 to perform the second motor control process.

Next, the method of detecting an abnormal motor current value in step 106 will be described. FIG. 23 shows WO98 /
33 shows a method for detecting a motor current detection value abnormality described in Japanese Patent No. 33270.

At step 122, the motor current target value IM
T is compared with a predetermined value I1, and if the motor current target value IMT is equal to or smaller than the predetermined value 11, the process branches to a process of ending this routine. On the other hand, the motor current target value IMT is
If it is larger than 1, the process branches to step 123.

In step 123, the motor current detection value I
If the motor current detection value IMS is smaller than the predetermined value I2, the process branches to step 124. Here, by setting the predetermined value I1> the predetermined value I2, the condition for branching to step 124 is when the motor current detection value IMS is smaller than the motor current target value IMT. In step 124, the continuation time of this state is compared with the predetermined time T1, and if the continuation time is equal to or longer than T1, the flow branches to step 125 to determine an abnormal motor current detection value. If it is less than T1, the process branches to a process of ending this routine.

If it is determined in step 123 that the motor current detection value IMS is equal to or larger than the predetermined value I2, the process proceeds to step 12
Branch to 6. Here, by setting the predetermined value I2 to be larger than the value at which the motor current detection value IMS can be determined to be normal, the condition for branching to step 126 is when the motor current detection value IMS is normal. Step 12
In step 6, if it is determined in step 125 that the abnormality of the detected motor current value is not determined, the process branches to a process of ending this routine. If the motor current detection value abnormality is determined in step 125, the flow branches to step 127 to release the determination of the motor current detection value abnormality.

By performing the above processing, the electric power steering control device configured as described above operates in the first motor control processing when the motor current detection circuit 24 is normal, An abnormality occurs in the current detection circuit 24, and the motor current detection value IMS becomes the predetermined value I2
When fixed below, the process is switched to the second motor control process. In the second motor control process, control is performed without using the motor current detection value IMS, so that an excessive current does not flow through the motor 8, and power steering control can be safely continued.

If the motor current detection value IMS returns to a normal value during the second motor control processing, the processing is switched to the first motor control processing. However, it can safely return to the normal state.

[0017]

However, in the above-described electric power steering control device, the motor current is limited by the back electromotive force of the motor, for example, when the steering wheel is suddenly steered, and the motor current target value IMT is not controlled. ,
There has been a problem that the motor current detection value IMS becomes small and a motor current detection value abnormality is erroneously detected. Further, in accordance with the erroneous detection, the control is switched to the second motor control process which is an open-loop control with inferior control accuracy, so that there is a problem that the steering feeling deteriorates.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has been made in consideration of an electric power in which an erroneous detection of an abnormality in a detected current value of a motor due to a back electromotive force of a motor is prevented to prevent a deterioration in steering feeling. It is intended to provide a steering control device.

[0019]

An electric power steering control device according to the present invention comprises: a target determining means for previously determining a target value of a current flowing to a motor; a motor current detecting means for detecting the motor current; A first motor control process for performing closed-loop control of a motor current flowing through the motor according to a value and the detected motor current, and a second motor performing open-loop control of the motor current flowing to the motor according to the target value Motor current control means having a control process, and when the target current is less than a predetermined value, determine whether the detected motor current has no abnormality,
Abnormality detecting means for switching the control of the motor current to the second motor control process when the abnormality is determined.

The motor current control means performs open loop control of the motor current in the second motor control process based on the motor resistance value and the target value of the motor current.

Further, when the motor is controlled in the second motor control process, a limiting means for preventing the motor current from flowing through a predetermined value or more is provided.

A target current determining means for determining a target value of a current flowing through the motor in advance; a motor current detecting means for detecting the motor current; and at least a proportional control of the control system based on the detected motor current and the target value. A first motor control process for performing closed-loop control of a motor current flowing to the motor using a term and an integral term, and a second motor for performing closed-loop control using the proportional term from the detected motor current and the target value A motor current control unit having a control process; determining whether the detected motor current is abnormal when the target value is less than a predetermined value; and controlling the motor current when the abnormality is determined by the second control. Abnormality detection means for switching to the motor control processing.

A target current determining means for determining a target value of a current flowing through the motor in advance; a motor current detecting means for detecting the motor current; and a target voltage determining means for determining a target value of the applied voltage to be applied to the motor. Means, a first motor control process for performing closed-loop control of a motor current flowing through the motor according to a target value of the current flowing through the motor and the detected motor current, and a motor based on the target value of the applied voltage. Motor current control means having a second motor control process for controlling the applied voltage; and determining whether or not the detected motor current is abnormal when the target current is less than a predetermined value, Abnormality detecting means for switching the control system to the second motor control processing at the time.

Also, the abnormality detecting means detects the abnormality and takes the second
In the motor control process, the control means for gradually reducing the target value of the motor current and stopping the power steering control when the motor current becomes equal to or less than the predetermined value is provided.

Further, the abnormality detecting means detects the abnormality and takes the second
And a control means for gradually reducing the motor applied voltage and stopping the power steering control when the applied voltage becomes equal to or less than a predetermined value at the time of control in the motor control process.

Further, the abnormality detecting means detects the abnormality and takes a second
Control means for stopping the power steering control when the target value of the motor current becomes equal to or less than a predetermined value during the control in the motor control process.

Also, the abnormality detecting means detects the abnormality and takes the second
Control means for stopping the power steering control when the target value of the motor applied voltage becomes equal to or less than a predetermined value during control in the motor control process.

Further, the abnormality detecting means detects the abnormality and
Control means for stopping the power steering control when the steering torque falls below a predetermined value during the control in the motor control process.

Further, during the motor control in the second motor control processing, the motor is controlled in the first motor control processing when the abnormality detecting means determines that the motor current is normal.

The abnormality detecting means determines the abnormality of the detected motor current value when a period in which the deviation between the target motor current value and the detected motor current value is equal to or more than the predetermined value is continued or integrated for a predetermined time or more.

Further, there is provided a second abnormality detecting means for determining whether or not the motor current detected irrespective of the target current is abnormal.

Further, the abnormality detecting means determines that the motor current detection value is abnormal when a state in which the deviation between the motor current target value and the motor current detection value is equal to or more than a predetermined value continues or is integrated for a first predetermined period or more. The second motor current detection value abnormality detecting means continues or integrates the state where the deviation between the motor current target value and the motor current detection value is equal to or larger than a predetermined value for a second predetermined period longer than the first predetermined period. Sometimes it is determined that the detected motor current value is abnormal.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described. Since the entire configuration and the configuration of the controller 9 are the same as those of the related art, description thereof will be omitted. Also, the first motor control processing and the second motor control processing are the same as those of the prior art, and thus the description is omitted.

The microcomputer 26 of the first embodiment
Will be described with reference to the flowchart of FIG. After starting the electric power steering control device, step 101
After the relay 21 is turned on at step 102, the steering torque detected from the torque sensor 3 is inputted at step 102, and at step 10
At 3, the vehicle speed is input from the vehicle speed sensor 7.

At step 104, the motor current target value IMT is determined from the steering torque and the vehicle speed. At step 105, the motor current detection value IMS is detected from the motor current detection circuit 24. At step 106, the abnormality of the motor current detection value IMS is determined. judge. If the result of the determination is normal, the flow branches to step 108 in step 107 to perform first motor control processing. On the other hand, if abnormal, the process branches to step 109 in step 107 to perform the second motor control process.

Next, the method of detecting an abnormality in the detected motor current value in step 106 of FIG. 22 in the present embodiment will be described with reference to FIG.
This will be described with reference to FIG. In step 121, the motor current target value IMT is compared with a predetermined value I0. If the motor current target value IMT is equal to or greater than I0, the process branches to a process of ending this routine. On the other hand, if the motor current target value IMT is less than the predetermined value I0, the process branches to step 122.
In step 122, the motor current target value IMT and the predetermined value I
If the motor current target value IMT is equal to or smaller than the predetermined value 11, the process branches to a process of ending this routine.
On the other hand, if the motor current target value IMT is larger than the predetermined value l1, the process branches to step 123.

In step 123, the motor current detection value I
If the motor current detection value IMS is smaller than the predetermined value I2, the process branches to step 124. Here, by setting the predetermined value I1> the predetermined value I2, the condition for branching to step 124 is when the motor current detection value IMS is smaller than the motor current target value IMT. In step 124, the continuation time of this state is compared with the predetermined time T1, and if the continuation time is equal to or longer than T1, the flow branches to step 125 to determine an abnormal motor current detection value. If it is less than T1, the process branches to a process of ending this routine.

If it is determined in step 123 that the detected motor current value IMS is equal to or larger than the predetermined value I2, the process proceeds to step 126.
Branch to Here, by setting the predetermined value I2 to be larger than the value at which the motor current detection value IMS can be determined to be normal, the condition for branching to step 126 is when the motor current detection value IMS is normal. Step 126
Then, in step 125, if the abnormality of the detected motor current value is not determined, the flow branches to a process of ending this routine. If the motor current detection value abnormality is determined in step 125,
The flow branches to step 127 to release the determination of the abnormal motor current detection value.

As described above, in the electric power steering control device according to the present invention, the motor current detection value abnormality is detected only when the motor current target value IMT is small (IMT <10). Value I
Erroneous detection of MS abnormality can be prevented. Further, by setting the predetermined value I0 so that the motor current target value IMT does not continue in a state (IMT ≧ I0) so large that the above-described motor current detection value abnormality detection is not performed, the motor current detection value is set. Is abnormally detected. In addition, at the time of sudden steering of the steering wheel, no overcurrent flows to the motor due to the back electromotive force of the motor, so that safety is not impaired even if no abnormality is detected.

When the motor current detection circuit 24 is normal, the operation is performed in the first motor control process. However, an abnormality occurs in the motor current detection circuit 24, and the motor current detection value falls below the predetermined value I2. If it is fixed to the second motor control processing. In the second motor control process, control is performed without using the motor current detection value IMS, so that an excessive current does not flow through the motor 8, and power steering control can be safely continued.

If the motor current detection value IMS returns to a normal value during the second motor control process, the process is switched to the first motor control process. However, it can safely return to the normal state. In addition, as the time to be compared with the predetermined time T1 in step 124, the duration is used, but the integration time may be used.

Embodiment 2 In the second motor control process in the first embodiment, no upper limit is set for the motor target voltage VMT, but as shown in FIG. Current may be prevented from flowing. In step 191, the motor voltage target value VMT is determined.
At 92, it is compared with a predetermined value Vmax. Motor voltage target value V
If MT is larger, the routine branches to step 193, where the motor voltage target value VMT is clipped to the predetermined value Vmax. If the motor voltage VMT is equal to or lower than the predetermined value Vmax, the process branches to a process of ending this routine.

Here, when the rated current value of the motor 8 is Im and the upper limit value Vmax of the motor voltage is Ramin when the lower limit value on the tolerance of the resistance value Ra of the motor is Ramin, Vmax = I
If the value is set to m × Ramin, a current higher than the rated current does not flow through the motor 8, and damage to the motor and the control device can be prevented.

Embodiment 3 FIG. Although the second motor control processing in the first and second embodiments does not use the motor current detection value IMS, the motor current control in the first motor control processing means as shown in the motor current control means 42 in FIG. The motor current detection value IMS may be used by constructing the means 42 (FIG. 19) by removing the integration term 52.

With this configuration, even if an abnormality occurs in the motor current detection value IMS and the process shifts to the second motor current control process, the second motor control process has only a proportional term. Only a current proportional to the value IMT flows, but no excessive current flows. Therefore, even in the second motor control process, closed loop control can be performed, and the reliability of the control device is improved.

Embodiment 4 FIG. In the second motor control process of the first and second embodiments, the motor current target value IMT is determined from the steering torque and the vehicle speed.
Motor target voltage VMT applied to the motor 8 based on T
However, as shown in FIG. 4, the target voltage determination means 61
For example, it may be determined from the voltage characteristics as shown in FIG.

Also in this case, in the second motor control process, the motor 8 is driven irrespective of the motor current detection value IMS, so that an excessive current does not flow and an excessive assist torque is not generated. improves.

Embodiment 5 In the first to third embodiments, when the abnormality of the motor current detection value IMS is detected, the processing shifts to the second motor control processing to change the motor current to the target current determination means 41.
Although control was performed by applying a motor applied voltage having the current value determined in (see FIG. 20), as shown in the flowchart of FIG. 6, if the process was shifted to the second motor control process,
In step 141, the motor current target value IMT is gradually lowered. If it is determined in step 142 that the motor current target value IMT has become zero, a process of turning off the relay 21 in step 143 may be performed.

In this case, by gradually reducing the assist torque from the motor 8 during the period from the detection of the current abnormality to the switching to the manual steering, it is possible to switch to the manual steering without a sudden change in the assist torque. The safety at the time of steering improves.

Embodiment 6 FIG. In the fourth embodiment, when the abnormality of the motor current detection value IMS is detected, the process shifts to the second motor control process, and the control is performed by setting the motor applied voltage to be the voltage value determined by the target voltage determination means 61. , FIG.
As shown in the flowchart of FIG. 7, if the process has shifted to the second motor control process, the motor voltage target value VMT is gradually decreased in step 151, and if it is determined in step 152 that the motor voltage target value VMT has become zero, Alternatively, a process of turning off the relay 21 in step 143 may be performed.

In this case, by gradually reducing the assist torque from the motor 8 during the period from the detection of the abnormal current to the switching to the manual steering, it is possible to switch to the manual steering without a sudden change in the assist torque. The safety at the time of steering improves.

Embodiment 7 In the first to third embodiments, when the abnormality of the motor current detection value IMS is detected, the processing shifts to the second motor control processing to change the motor current to the target current determination means 41.
The control was performed by applying the motor application voltage so as to have the current value determined in (see FIG. 20). However, as shown in the flowchart of FIG.
4 is equal to the predetermined value ITH
(For example, 0 A) or less, and if it is equal to or less than the predetermined value ITH, a process of turning off the relay 21 may be performed in step 143.

With the above-described configuration, even if a motor current detection value abnormality occurs, as in the first embodiment,
The motor 8 can be controlled without generating excessive assist torque. Further, since the relay 21 is turned off and the steering is switched to the manual steering in a state where the assist torque from the motor 8 is lost, it is possible to safely switch to the manual steering without causing a sudden change in the assist torque.

Embodiment 8 FIG. In the fourth embodiment, when the abnormality of the motor current detection value IMS is detected, the process shifts to the second motor control process, and the control is performed by setting the motor applied voltage to be the voltage value determined by the target voltage determination means 61. , FIG. 9
As shown in the flowchart, it is determined in step 181 whether or not the motor voltage target value VMT is equal to or lower than a predetermined value VTH (for example, 0 V). If the motor voltage target value VMT is equal to or lower than the predetermined value VTH, the relay 21 is turned off in step 143 to stop power steering control. You may do so. If the motor voltage target value VMT is larger than the predetermined value VTH in step 181, step 102
Repeat the process from.

With the above-described configuration, even if a motor current detection value abnormality occurs, as in the first embodiment,
The motor 8 can be controlled without generating excessive assist torque. Further, since the relay 21 is turned off and the steering is switched to the manual steering in a state where the assist torque from the motor 8 is lost, it is possible to safely switch to the manual steering without causing a sudden change in the assist torque.

Embodiment 9 FIG. In the first to eighth embodiments,
When the abnormality of the motor current detection value IMS is detected, the process proceeds to the second motor control process to perform the motor control. However, as shown in the flowchart of FIG. TT
H (for example, 1 N / m) or less, and if the steering torque is equal to or less than the predetermined value TTH, the relay 21 may be turned off in step 143 to stop the control of the power steering. If the steering torque is larger than the predetermined value TTH in step 171, the processing from step 102 is repeated.

By performing the processing as described above, the motor can be controlled without generating excessive assist even if the detected motor current value is abnormal, as in the first embodiment, and the steering force is further reduced. Since the relay 21 is turned off and switched to manual steering in a sufficiently small state, it is possible to safely switch to manual steering without causing a sudden change in assist torque.

Embodiment 10 FIG. In the first to ninth embodiments, the motor current detection value abnormality detection processing is performed when the motor current target value IMT is larger than I1 and the motor current detection value IM
When S is smaller than I2, the motor current detection value abnormality is determined. However, as shown in FIG. 11, the state where the difference between the motor current target value IMT and the motor current detection value IMS is larger than the predetermined value ε1 is T2 (for example, several tens msec to several About 100msec)
When the above is continued, the abnormality of the detected motor current value may be determined. Also in this case, similarly to the first embodiment, even if a motor current detection value abnormality occurs, the motor can be controlled without generating excessive assist.

Embodiment 11 FIG. Embodiments 1 to 10 above
Then, the motor current target value IMT is large (IMT ≧ I
In the case of 0), the abnormality detection of the motor current detection value is not performed, but a process of detecting the abnormality of the motor current detection value when the motor current target value IMT is large may be added.

FIG. 12 is a flowchart showing a control processing method according to the present embodiment. Steps 101 to 109 are the same as those in the first embodiment, and a description thereof will be omitted. After detecting the motor current detection value IMS in step 105,
At step 131, the second motor current detection value abnormality is detected, and then, at step 106, the first motor current detection value abnormality detection, which is the motor current detection value abnormality detection processing of the first embodiment, is performed.

Here, the second motor current detection value abnormality detection processing in step 131 will be described with reference to FIG. In step 141, the motor current target value IMT is compared with a predetermined value I3.
In the following cases, the process branches to a process of ending this routine. On the other hand, if the motor current target value IMT is larger than the predetermined value 13, the process branches to step 142.

In step 142, the motor current detection value I
MS is compared with a predetermined value I4. If the detected motor current value IMS is equal to or greater than the predetermined value I4, the process branches to a process of ending this routine. On the other hand, if the detected motor current value is less than the predetermined value I4, the flow branches to step 143. Here, the predetermined value I
3> By setting the predetermined value I4, step 143
The condition for branching to is that the motor current target value IMT is
This is the case where the motor current detection value IMS is small. here,
I3 and I4 are both set to values larger than I0. In step 143, the continuation time of this state and the predetermined time T2 (T2 is sufficiently longer than the standard time during which a difference occurs between the motor current target value IMT and the motor current detection value IMS due to the back electromotive force of the motor. If the continuation time is equal to or longer than T2, the flow branches to step 144 to determine an abnormality in the detected motor current value. If it is less than T2, the flow branches to a process for ending this routine. Note that T2 is set to a value larger than T1.

When the abnormality of the detected motor current value is determined in step 131, the motor current target value IMT may be gradually reduced and the motor assist may be stopped when the motor current target value IMT becomes sufficiently small.

In the present embodiment, at step 131, even if the motor current target value IMT is large (IMT ≧ I0), the motor current detection value abnormality is detected. Moreover, the abnormality determination time T2 is a value (for example, about several seconds) which is sufficiently larger than a standard time during which a difference between the motor current target value IMT and the motor current detection value IMS occurs due to the back electromotive force of the motor. Therefore, erroneous detection due to the back electromotive force of the motor does not occur. Therefore, a safer and more reliable electric power steering control device can be realized.

Embodiment 12 FIG. In the eleventh embodiment, the motor current target value IMT and the motor current detection value IMS are used in the second motor current detection value abnormality detection processing in step 131 in FIG. 12, but as shown in FIG. The state where the difference is larger than the predetermined value ε2 is T2 (for example, several seconds).
In this case, the abnormality of the detected motor current value may be determined when the above operation is continued. In this case as well, the motor current target value IMT is large (IMT ≧ I
Even in the case of 0), abnormality detection of the motor current detection value is performed, so that a safer and more reliable electric power steering controller can be realized.

[0066]

According to the present invention, there is provided an electric power steering control apparatus comprising: a target determining means for determining a target value of a current flowing through a motor; a motor current detecting means for detecting the motor current; A first motor control process for performing closed-loop control of a motor current flowing to the motor in accordance with the set motor current, and a second motor control process for performing open-loop control of the motor current to flow in the motor in accordance with the target value Motor current control means, and when the target current is less than a predetermined value, determines whether or not the detected motor current is abnormal, and controls the motor current when the abnormality is determined by the second motor control. Abnormality detection means for switching to the process. Generally, when the steering wheel is sharply steered such that the target current becomes large, the motor is driven by the back electromotive force of the motor. Since the overcurrent does not flow through the motor, rather than a problem without the anomaly detection, it is possible to prevent the handle sudden steering time of the motor current detection value abnormality erroneous detection.

The motor current control means performs open loop control of the motor current in the second motor control process based on the motor resistance value and the target value of the motor current.
The control can be performed without using the detected abnormal motor current, and the steering feeling can be prevented from deteriorating.

When the motor is controlled in the second motor control process, a limiting means is provided so that the motor current does not flow beyond a predetermined value. Damage to the control device can be prevented.

Further, a target current determining means for previously determining a target value of a current to be supplied to the motor, a motor current detecting means for detecting the motor current, and at least a proportional control of the control system based on the detected motor current and the target value. A first motor control process for performing closed-loop control of a motor current flowing to the motor using a term and an integral term, and a second motor for performing closed-loop control using the proportional term from the detected motor current and the target value A motor current control unit having a control process; determining whether the detected motor current is abnormal when the target value is less than a predetermined value; and controlling the motor current when the abnormality is determined by the second control. Abnormality detection means for switching to the motor control process. In the event of an abnormality, only the proportional term is controlled, and a current proportional to the motor target current value flows. A Runomi, excessive current does not flow, yet can also improve the reliability of control because perform closed-loop control be abnormal.

Further, a target current determining means for previously determining a target value of a current flowing through the motor, a motor current detecting means for detecting the motor current, and a target voltage determining means for determining a target value of the applied voltage to be applied to the motor. Means, a first motor control process for performing closed-loop control of a motor current flowing through the motor according to a target value of the current flowing through the motor and the detected motor current, and a motor based on the target value of the applied voltage. Motor current control means having a second motor control process for controlling the applied voltage; and determining whether or not the detected motor current is abnormal when the target current is less than a predetermined value, Abnormality detecting means for switching the control system to the second motor control process at the time of the steering operation. Since the overcurrent to the motor by back electromotive force of no flow, no problem without the anomaly detection, it is possible to prevent the handle sudden steering time of the motor current detection value abnormality erroneous detection.

Further, the abnormality detecting means detects the abnormality and
At the time of control in the motor control process, the control means for gradually reducing the target value of the motor current and stopping the power steering control when the motor current becomes equal to or less than a predetermined value,
When an abnormality is detected, the assist torque can be gradually reduced to stop the control, a rapid change in the assist torque can be prevented, and the steering feeling can be improved.

Further, the abnormality detecting means detects the abnormality and takes the second
Control means for gradually decreasing the motor applied voltage and stopping the power steering control when the applied voltage becomes equal to or less than a predetermined value during the control in the motor control process, and gradually reducing the assist torque when an abnormality is detected. , Control can be stopped and a sudden change in assist torque can be prevented, and steering feeling can be improved.

Further, the abnormality detecting means detects the abnormality and
A control means for stopping the power steering control when the target value of the motor current becomes equal to or less than a predetermined value during the control in the motor control process, and the control is continued while the assist torque is required; Since the control is stopped when it becomes unnecessary, it is possible to prevent a sudden change in the assist torque and improve the steering feeling.

Further, the abnormality detecting means detects the abnormality and
Control means for stopping the power steering control when the target value of the motor applied voltage becomes equal to or less than a predetermined value during the control in the motor control process. Since the control is stopped when the torque becomes unnecessary, a sudden change in the assist torque can be prevented, and the steering feeling can be improved.

Further, the abnormality detecting means detects the abnormality and
In the control of the motor control processing, the control means for stopping the power steering control when the steering torque falls below a predetermined value is provided.The control is continued as long as the assist torque is required. When this happens, the control is stopped, so that a rapid change in the assist torque can be prevented, and the steering feeling can be improved.

When the abnormality detection means determines that the motor current is normal during the motor control in the second motor control process, the motor is controlled by the first motor control process. Even if the process shifts to the first motor control process, the process can return to the first motor control process, and the reliability of the control can be improved.

The abnormality detecting means determines abnormality of the motor current detection value when a period in which the deviation between the motor current target value and the motor current detection value is equal to or more than a predetermined value is continued or integrated for a predetermined time or more. Erroneous detection of an abnormality can be more reliably prevented.

Further, there is provided second abnormality detecting means for determining whether or not the detected motor current is abnormal regardless of the target current. Even if the target current is large, An abnormality can be detected.

Further, the abnormality detecting means determines that the motor current detection value is abnormal when the state in which the deviation between the motor current target value and the motor current detection value is a predetermined value or more continues or is integrated for a first predetermined period or more. The second motor current detection value abnormality detecting means continues or integrates the state where the deviation between the motor current target value and the motor current detection value is equal to or larger than a predetermined value for a second predetermined period longer than the first predetermined period. The time until the abnormality is determined by the second motor current detection value abnormality detection means for performing abnormality determination regardless of the magnitude of the target current is determined as the back electromotive force. It can be set longer than the standard time when the target current and the detected current deviate due to the influence, and even if the target current is large, erroneous detection due to the influence of the back electromotive force can be prevented, Regardless, always it has abnormality monitoring, it is possible to improve the reliability of the device.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a motor current abnormality detection operation according to the first embodiment.

FIG. 2 is a flowchart illustrating an operation of performing open-loop control of a motor voltage and clipping a motor voltage upper limit value.

FIG. 3 is a block diagram illustrating a motor current control means in a closed loop control system using only a proportional term.

FIG. 4 is a block diagram illustrating each operation when the motor voltage is subjected to open-loop control.

FIG. 5 is a voltage characteristic diagram used when determining a motor target voltage value from a steering torque and a vehicle speed.

FIG. 6 is a flowchart illustrating a power steering control operation according to the fifth embodiment.

FIG. 7 is a flowchart illustrating a power steering control operation according to the sixth embodiment.

FIG. 8 is a flowchart illustrating a power steering control operation according to the seventh embodiment.

FIG. 9 is a flowchart illustrating a power steering control operation according to the eighth embodiment.

FIG. 10 is a flowchart illustrating a power steering control operation according to the ninth embodiment.

FIG. 11 is a flowchart illustrating a motor current abnormality detection operation according to the tenth embodiment.

FIG. 12 is a flowchart illustrating control processing of a microcomputer in a controller according to the eleventh embodiment.

FIG. 13 is a flowchart illustrating a motor current detection circuit abnormality detection operation according to the eleventh embodiment.

FIG. 14 is a flowchart illustrating a motor current detection circuit abnormality detection operation according to the twelfth embodiment.

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

FIG. 16 is a diagram illustrating a control process of a microcomputer in a conventional controller.

FIG. 17 is a block diagram when a motor current is performed by a closed loop control system.

FIG. 18 is a current characteristic diagram used when determining a target current value of a motor from a steering torque and a vehicle speed.

19 is a block diagram illustrating a current control unit in FIG. 18 using a closed loop control system using a proportional term and an integral term.

FIG. 20 is a block diagram in the case where the motor current is controlled by open loop control.

FIG. 21 is a block diagram illustrating a motor current control unit using an open loop control system.

FIG. 22 is a flowchart illustrating an operation of a microcomputer in the electric power steering control device.

FIG. 23 is a flowchart illustrating a motor current detection value abnormality detection unit of the conventional electric power steering control device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 steering wheel 2 steering shaft 3 torque sensor 4 reduction gear 7 vehicle speed sensor 8 motor 9 controller 24 motor current detection circuit 41 target current determination means 42 motor current control means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) B62D 119: 00 B62D 119: 00 (72) Inventor Hiroshi Nishimura 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 2-3 Rishi Electric Co., Ltd. (72) Inventor Yuji Takatsuka 6-1, 1-2 Hamayama-dori, Hyogo-ku, Kobe-shi, Hyogo Inside Mitsubishi Electric Control Software Co., Ltd. (72) Inventor Shiki Otagaki 2-2-2, Marunouchi, Chiyoda-ku, Tokyo No. Mitsubishi Electric Co., Ltd. (72) Inventor Shinji Hironaka 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Masataka Izawa 1-4-4 Chuo, Wako-shi, Saitama No. 1 Inside Honda R & D Co., Ltd. (72) Inventor Osamu Tsurumiya 1-4-1 Chuo, Wako-shi, Saitama Pref. F term (reference) 3D032 CC34 DA15 DA23 DA64 DA65 DD17 DE09 EC23 EC24 GG01 3D033 CA03 CA13 CA16 CA20 CA21 CA32 5H550 AA16 BB08 EE08 GG05 GG08 JJ03 JJ08 LL01 LL22 LL48 MM02 5H571 AA03 CC02 EE08 LL01 LL01 LL01

Claims (14)

[Claims] 1. A target determining means for previously determining a target value of a current flowing to a motor, a motor current detecting means for detecting the motor current, and a current flowing to the motor according to the target value and the detected motor current. Motor current control means comprising: a first motor control process for performing closed-loop control of a motor current; and a second motor control process for performing open-loop control of a motor current flowing to the motor according to the target value;
When the target current is less than a predetermined value, determine whether there is an abnormality in the detected motor current, and when the abnormality is determined, switch the control of the motor current to the second motor control processing. An electric power steering control device comprising: 2. The electric power steering system according to claim 1, wherein the motor current control means performs open loop control of the motor current in the second motor control process based on a resistance value of the motor and a target value of the motor current. Control device. 3. The electric power steering control device according to claim 2, wherein a limiter for preventing the motor current from flowing through a predetermined value or more is provided when the motor control is performed in the second motor control process. 4. A target current determining means for previously determining a target value of a current flowing through the motor, a motor current detecting means for detecting the motor current, and at least a proportional control of the control system based on the detected motor current and the target value. A first motor control process for performing closed-loop control of a motor current flowing to the motor using a term and an integral term, and a second motor for performing closed-loop control using the proportional term from the detected motor current and the target value A motor current control unit having a control process; determining whether the detected motor current is abnormal when the target value is less than a predetermined value; and controlling the motor current when the abnormality is determined by the second control. An electric power steering control device, comprising: abnormality detection means for switching to a motor control process. 5. A target current determining means for determining a target value of a current flowing through a motor in advance, a motor current detecting means for detecting the motor current, and a target voltage determining means for determining a target value of an applied voltage to be applied to the motor. Means, a first motor control process for performing closed-loop control of a motor current flowing through the motor according to a target value of the current flowing through the motor and the detected motor current, and a motor based on the target value of the applied voltage. Motor current control means having a second motor control process for controlling the applied voltage; and determining whether or not the detected motor current is abnormal when the target current is less than a predetermined value, An electric power steering control device, comprising: abnormality detection means for switching a control system to the second motor control processing at the time. 6. A control means for detecting a malfunction and controlling the second motor control processing to gradually reduce a target value of the motor current and stop the power steering control when the motor current becomes equal to or less than a predetermined value. The electric power steering control device according to any one of claims 1 to 4, further comprising: 7. A control means for gradually reducing an applied voltage to a motor and stopping power steering control when the applied voltage becomes equal to or less than a predetermined value when the abnormality detection means detects an abnormality and performs control in a second motor control process. The electric power steering control device according to claim 5, wherein: 8. The control apparatus according to claim 1, further comprising: control means for stopping power steering control when the target value of the motor current becomes equal to or less than a predetermined value when the abnormality detection means detects an abnormality and performs control in the second motor control processing. The electric power steering control device according to any one of claims 1 to 4, wherein: 9. Control means for stopping power steering control when a target value of a voltage applied to a motor becomes equal to or less than a predetermined value when the abnormality detection means detects an abnormality and performs control in the second motor control processing. The electric power steering control device according to claim 5, wherein: 10. A control device for stopping power steering control when a steering torque becomes equal to or less than a predetermined value when the abnormality detection unit detects an abnormality and performs control in a second motor control process. The electric power steering control device according to claim 1. 11. The motor according to claim 1, wherein the motor is controlled by the first motor control process when the abnormality detection means determines that the motor current is normal during the motor control in the second motor control process. An electric power steering control device according to any one of the above. 12. The abnormality detecting means determines an abnormality in the motor current detection value when a period in which the deviation between the motor current target value and the motor current detection value is a predetermined value or more continues or integrates for a predetermined time or more. The electric power steering control device according to claim 1. 13. The apparatus according to claim 1, further comprising: second abnormality detecting means for judging whether or not there is an abnormality in the motor current detected independently of the target current. An electric power steering control device as described in the above. 14. An abnormality detecting means determines that the detected motor current value is abnormal when a state in which a deviation between the motor current target value and the detected motor current value is equal to or more than a predetermined value continues or is integrated for a first predetermined period or more. The second motor current detection value abnormality detecting means is configured to determine that the state in which the deviation between the motor current target value and the motor current detection value is equal to or greater than a predetermined value is longer than a first predetermined period.
14. The electric power steering control device according to claim 13, wherein it is determined that the detected motor current value is abnormal when the continuation or the integration is continued for a predetermined period or more.