JP2011195089A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device that can perform determination of failure with a simple structure and high reliability.SOLUTION: As a motor 12, a brushless motor having biphasic motor coils 12a and 12b is adopted. An ECU 11 includes a microcomputer 21a and a drive circuit 22a in a first system for performing a sinusoidal power distribution to the first phase motor coil 12a, and a microcomputer 21b and a drive circuit 22b in a second system for performing a cosine power distribution to the second phase motor coil 12b. The microcomputers 21a and 21b individually perform a current feedback control on the corresponding phase, thereby, generating a motor control signal of the corresponding phase, as well as performing the determination of failure by monitoring a generation of an excessive current deviation of the other phase.

Description

  The present invention relates to an electric power steering apparatus.

  2. Description of the Related Art Conventionally, there is an electric power steering device (EPS) using a motor as a drive source as a power steering device for a vehicle. Such EPS has a feature that a layout has a high degree of freedom and energy consumption is small. ing. Therefore, in recent years, the adoption has been promoted in a wide range of vehicle types from small vehicles to large vehicles.

  Conventionally, in EPS, many abnormality determination processes (diagnostic processes) are performed in an electronic control device (such as a microcomputer) that executes the power assist control. For example, a microcomputer is composed of a CPU, a memory (RAM and ROM), and various electronic circuits (A / D conversion, etc.). When the microcomputer is started up (when the ignition is ON), an execution program and its work data An initial check is performed to confirm that the memory serving as the storage area is normal (see, for example, Patent Document 1). Even after startup, it is monitored whether the microcomputer and various electronic circuits under its control are functioning normally. And in the abnormality determination process, when some abnormality is detected, it is configured to ensure high reliability and safety by promptly fail-safe.

JP 2006-331086 A

  However, in recent years, in EPS, various compensation controls are executed in order to achieve a better steering feeling, and the time required for the initial check is increased due to the increase in the memory capacity associated therewith. Is getting longer. In addition, the function check after activation is performed, for example, by providing a monitoring microcomputer independent of the microcomputer (main microcomputer) that executes power assist control. In this case, the main microcomputer is sent from the monitoring microcomputer. Test calculations must be performed in real time. Further, by providing a new monitoring circuit (abnormality determination circuit) including such a monitoring microcomputer, the main microcomputer needs to monitor whether or not the monitoring circuit functions normally. For example, the processing capability required to execute the abnormality determination has been steadily increasing, and this has also contributed to increase the manufacturing cost.

  In addition, by providing a large number of monitoring circuits, the increase in the failure occurrence rate due to the increase in the number of constituent elements becomes remarkable, and as a result, there is no influence on the operation of EPS due to the execution of various abnormality determinations. There is a possibility that even a trivial event without a mark will be judged as abnormal. And since this is counted as a failure, there is a problem that the failure occurrence rate is further raised. In this respect, there is still room for improvement.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric power steering apparatus that can perform abnormality determination with a simple configuration and high reliability.

  In order to solve the above problems, the invention according to claim 1 is directed to a steering force assisting device that applies an assist force to a steering system using a motor as a drive source, and a control unit that controls the operation of the steering force assisting device. The control means includes a control signal output means for outputting a motor control signal to generate a motor torque corresponding to the assist force, and a drive circuit for supplying drive power based on the motor control signal to the motor. The motor is a brushless motor having a two-phase motor coil, and the control means is a first system that performs sine energization on the first-phase motor coil. A control signal output means and a drive circuit; and a second system of control signal output means and a drive circuit for performing cosine energization on the motor coil of the second phase, The control signal output means performs the current feedback control independently to generate the motor control signal for the corresponding phase, and performs an abnormality determination by monitoring the occurrence of an excessive current deviation in the other phase. This is the gist.

  According to the above configuration, when any abnormality occurs in the two control systems, particularly in the electronic control device (microcomputer) constituting each control signal output means, there is an abnormality that affects the power assist control. When it occurs, the abnormality always appears in the current deviation of the other phase. Accordingly, each of the control signal output means monitors the current deviation of the other phase mutually, specifically, by monitoring the occurrence of the excessive deviation, the abnormality occurs in at least one of the two control systems. Can be detected. As a result, other abnormality determination control (monitoring circuit) related to the electronic control device constituting each control signal output means, such as the initial check of the memory at the time of startup as described above, is eliminated, and the above-mentioned other-phase current deviation is reduced. It is possible to replace the abnormality determination based on mutual monitoring. As a result, not only the start-up time can be shortened, but also the cost reduction due to a reduction in processing capability required for each electronic control device and the failure occurrence rate due to the reduction in circuit scale can be achieved.

  According to a second aspect of the present invention, there is provided a first current sensor used by the control signal output means for detecting a current of a corresponding phase, and a second current sensor used by the control signal output means for detecting a current of another phase; The main point is that they are independently provided.

  According to the above configuration, abnormalities that occur in the process of detecting the actual current value of each phase (abnormalities in the current sensor body constituting the current detection element and its signal wiring, etc.) also appear in the current deviation of other phases. It becomes like this. Therefore, the abnormality determination of the current detection element can be replaced with the abnormality determination based on the mutual monitoring of the other-phase current deviation as described above. As a result, the configuration is further simplified and the reliability is improved. be able to.

  According to a third aspect of the present invention, two independent sensor signals capable of detecting a steering torque transmitted to the steering system are input to the control means, and each control signal output means corresponds to The gist is that each independently calculates a current command value based on the steering torque detected by the sensor signal.

  According to the above configuration, an abnormality (such as an abnormality in the torque sensor main body constituting the steering torque detection element and its signal wiring) generated in the process of detecting the steering torque also appears as a current deviation. Therefore, the abnormality determination of the steering torque detection element can be replaced with the abnormality determination based on the mutual monitoring of the other-phase current deviation as described above. As a result, the structure can be further simplified and the reliability can be improved. Can be planned.

  According to a fourth aspect of the present invention, the control signal output means corresponding to the first phase uses the first rotation angle sensor used for detecting the motor rotation angle, and the control signal output means corresponding to the second phase corresponds to the motor rotation angle. The gist is that the second rotation angle sensor used for detection is provided independently.

  That is, the current command value for performing sine wave energization (sine energization and cosine energization) for each phase of the two-phase brushless motor is a value corresponding to the motor rotation angle. Therefore, according to the above-described configuration, an abnormality that occurs in the process of detecting the motor rotation angle (an abnormality in the rotation angle sensor body that constitutes the motor rotation angle detection element, the signal wiring, etc.) To appear. As a result, the abnormality determination of the detection element for the motor rotation angle can be replaced with the abnormality determination based on the mutual monitoring of the other-phase current deviation as described above. As a result, further simplification of the configuration and reliability can be achieved. Improvements can be made.

  The gist of the invention described in claim 5 is that the control means stops power assist control for applying assist force to the steering system when it is determined to be abnormal by the abnormality determination.

  According to the said structure, a motor can be stopped rapidly and a fail safe can be aimed at.

  ADVANTAGE OF THE INVENTION According to this invention, the electric power steering apparatus which can perform abnormality determination with a simple structure and high reliability can be provided.

The schematic block diagram of an electric power steering device (EPS). The block diagram which shows the electric constitution of EPS. The block diagram which shows schematic structure of each microcomputer. The flowchart which shows the process sequence of abnormality determination.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, in the electric power steering apparatus (EPS) 1 of this embodiment, a steering shaft 3 to which a steering 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. The rotation of the steering shaft 3 accompanying the steering operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4. The steering shaft 3 of this embodiment is formed by connecting a column shaft 3a, an intermediate shaft 3b, and a pinion shaft 3c. Then, the reciprocating linear motion of the rack shaft 5 accompanying the rotation of the steering shaft 3 is transmitted to a knuckle (not shown) via tie rods 6 connected to both ends of the rack shaft 5, whereby the steering angle of the steered wheels 7. That is, the traveling direction of the vehicle is changed.

  Further, the EPS 1 includes an EPS actuator 10 as a steering force assisting device that applies an assist force for assisting a steering operation to the steering system, and an ECU 11 as a control unit that controls the operation of the EPS actuator 10. .

  The EPS actuator 10 of the present embodiment is configured as a so-called column-type EPS actuator in which a motor 12 that is a drive source is drivingly connected to a column shaft 3 a via a speed reduction mechanism 13. In the present embodiment, a known worm and wheel is adopted as the speed reduction mechanism 13. The EPS actuator 10 is configured to apply the motor torque as an assist force to the steering system by decelerating the rotation of the motor 12 and transmitting it to the column shaft 3a.

  On the other hand, a torque sensor 14 and a vehicle speed sensor 15 are connected to the ECU 11. In this embodiment, the torque sensor 14 can detect the steering torque τ transmitted through the steering shaft 3 based on the torsion bar 16 provided in the middle of the column shaft 3 a and the torsion of the torsion bar 16. Two independent sensor units 14a and 14b for outputting sensor signals (Sa, Sb) are provided.

  Such a torque sensor includes, for example, a plurality of Hall ICs as sensor units 14a and 14b serving as detection elements on the radially outer side of a sensor core (not shown) that generates a magnetic flux change due to torsion of the torsion bar 16. Can be formed (see, for example, JP-A-2003-149062). Then, the ECU 11 of the present embodiment uses the motor 12 that is the drive source of the EPS actuator 10 based on the steering torque τ (τ1, τ2) detected by the torque sensor 14 and the vehicle speed V detected by the vehicle speed sensor 15. The power assist control is executed by controlling the assist torque generated.

Next, the electrical configuration of the EPS of this embodiment will be described.
As shown in FIG. 2, in the present embodiment, a brushless motor having two-phase motor coils 12 a and 12 b is employed as the motor 12 that is a drive source of the EPS actuator 10. Then, the ECU 11 supplies the drive power to each phase by performing sine wave energization, that is, sine energization (sin energization) and cosine energization (cos energization) with the phases shifted from each other by 90 °. It is the composition which performs.

  More specifically, the ECU 11 of the present embodiment is provided corresponding to the first system microcomputer 21a and the drive circuit 22a provided corresponding to the first phase motor coil 12a and the second phase motor coil 12b. A second system microcomputer 21b and a drive circuit 22b. And each drive circuit 22a, 22b carries out the sine wave energization with respect to the motor coil 12a, 12b of the corresponding phase (corresponding phase) independently based on the motor control signal which the corresponding microcomputer 21a, 21b outputs, respectively. Execute.

  In the present embodiment, a known PWM inverter formed by connecting four switching elements SW1 to SW4 in an H bridge shape is employed for each of the drive circuits 22a and 22b. Predrivers 23a and 23b are interposed between the microcomputers 21a and 21b serving as control signal output means and the drive circuits 22a and 22b, respectively. Motor control signals output from the microcomputers 21a and 21b are as follows. Are input to the corresponding pre-drivers 23a and 23b. And each pre-driver 23a, 23b applies a gate drive voltage to each switching element SW1-SW4 which comprises drive circuit 22a, 22b as mentioned above based on the motor control signal input.

  That is, each of the drive circuits 22a and 22b turns on / off each of the switching elements SW1 to SW4 in response to the gate drive voltage, thereby applying a voltage based on the duty ratio indicated in the motor control signal to the corresponding phase. Applied to the motor coils 12a and 12b. As a result, the first-system microcomputer 21a and the drive circuit 22a (and the pre-driver 23a) execute sine energization for the corresponding first-phase motor coil 12a, and the second-system microcomputer 21b and the drive circuit 22b. (And the pre-driver 23b) are configured to perform cosine energization to the corresponding second-phase motor coil 12b.

  More specifically, as shown in FIG. 3, each of the microcomputers 21a and 21b includes basic assist control units 25a and 25b for calculating a basic assist control amount Ias * corresponding to the target assist force, and the basic assist control. Current command value calculation units 26a and 26b for calculating the current command values I_sin * and I_cos * of each phase according to the amount Ias * and the motor rotation angle θ are provided.

  In the present embodiment, among the two sensor units 14a and 14b constituting the torque sensor 14 (see FIG. 1), the sensor signal Sa output from the sensor unit 14a is input to the first system microcomputer 21a. The microcomputer 21a detects the steering torque τ1 based on the sensor signal Sa. Further, the sensor signal Sb output from the sensor unit 14b is input to the second-system microcomputer 21b, and the microcomputer 21b detects the steering torque τ2 based on the sensor signal Sb. In addition, about the vehicle speed V, the common value detected by the vehicle speed sensor 15 is input into each microcomputer 21a, 21b via the in-vehicle network (CAN) which is not illustrated. Then, the basic assist control units 25a and 25b are each independently based on the steering torque τ (τ1, τ2) and the vehicle speed V detected independently by the microcomputers 21a and 21b, respectively. Is calculated.

  The motor 12 of the present embodiment is provided with two rotation angle sensors 27a and 27b. The microcomputers 21a and 21b each independently detect the motor rotation angle θ (θ1, θ2) based on the output signals of the rotation angle sensors 27a and 27b.

  Specifically, the first system microcomputer 21a detects the motor rotation angle θ1 based on the output signal of the rotation angle sensor 27a, and the second system microcomputer 21b detects the motor based on the sensor signal output from the rotation angle sensor 27b. The rotation angle θ2 is detected. That is, in the present embodiment, the rotation angle sensor 27a constitutes a first rotation angle sensor, and the rotation angle sensor 27b constitutes a second rotation angle sensor. Then, each current command value calculation unit 26a, 26b determines the basic assist control amount Ias * calculated independently in each microcomputer 21a, 21b and the motor rotation angle θ (θ1, θ2) detected independently as described above. Based on this, current command values I_sin * and I_cos * for sine energization and cosine energization for each phase of the motor 12 are calculated independently.

  Furthermore, as shown in FIG. 2, in the present embodiment, the power lines 28a and 28b of the respective phases are provided with current sensors 29a and 29b, and the microcomputers 21a and 21b are connected to the current sensors 29a. , 29b, the actual current values I_sin and I_cos of the corresponding phase are detected independently of each other. The microcomputers 21a and 21b are independent of each other so that the detected actual current values I_sin and I_cos follow the current command values I_sin * and I_cos * calculated by the current command value calculation units 26a and 26b. By executing current feedback control for the corresponding phase, a motor control signal for the corresponding phase is generated.

  Specifically, as shown in FIG. 2 and FIG. 3, the first system microcomputer 21a is based on the output signal of the current sensor 29a provided on the power line 28a corresponding to the first phase motor coil 12a. The actual current value I_sin of the first phase that executes sine energization is detected. In the microcomputer 21a, the actual current value I_sin is input to the subtractor 30a together with the current command value I_sin * calculated by the current command value calculation unit 26a. The microcomputer 21a inputs the current deviation ΔI_sin calculated by the subtractor 30a to the F / B control unit 31a, thereby executing current feedback control for the corresponding first phase.

  Specifically, the F / B control unit 31a calculates a proportional component obtained by multiplying an input current deviation ΔI_sin by a proportional gain, and an integral component obtained by multiplying an integral value of the current deviation ΔI_sin by an integral gain. By adding, the first phase voltage command value V_sin * is calculated (PI control). The microcomputer 21a inputs the voltage command value V_sin *, which is the result of the feedback control calculation in the F / B control unit 31a, to the PWM control output unit 32a, thereby energizing the corresponding first phase. The motor control signal is generated.

  Similarly, the second-system microcomputer 21b performs a second-phase actual current that performs cosine energization based on the output signal of the current sensor 29b provided on the power line 28b corresponding to the second-phase motor coil 12b. The value I_cos is detected. In the microcomputer 21b, the actual current value I_cos is input to the subtracter 30b together with the current command value I_cos * calculated by the current command value calculation unit 26b. The microcomputer 21b inputs the current deviation ΔI_cos calculated in the subtractor 30b to the F / B control unit 31b, thereby executing current feedback control for the corresponding second phase.

  The F / B control unit 31b also integrates the proportional component obtained by multiplying the input current deviation ΔI_cos by the proportional gain and the integral value of the current deviation ΔI_cos, as in the F / B control unit 31a. The second phase voltage command value V_cos * is calculated by adding the integral component obtained by multiplying by (PI control). The microcomputer 21b inputs the voltage command value V_cos *, which is the result of the feedback control calculation in the F / B control unit 31b, to the PWM control output unit 32b, thereby energizing the corresponding second phase. The motor control signal is generated.

(Abnormality judgment)
Next, an aspect of abnormality determination in the EPS of the present embodiment will be described.
As shown in FIG. 2, in the present embodiment, the power lines 28a and 28b of the respective phases are provided with the second current sensor 35a independently of the current sensors (first current sensors) 29a and 29b, respectively. , 35b are provided. The microcomputers 21a and 21b independently detect the actual current values I_sin ′ and I_cos ′ of the other phases based on the output signals of the second current sensors 35a and 35b, respectively.

  The microcomputers 21a and 21b calculate current deviations (ΔI_sin ′ and ΔI_cos ′) of other phases based on the actual current values I_sin ′ and I_cos ′ detected by the second current sensors 35a and 35b. And the abnormality determination is performed independently by mutually monitoring the current deviation of other phases.

  That is, the calculation methods of the current command values I_sin * and I_cos * by the microcomputers 21a and 21b are the same, and the object of detection of the state quantity (steering torque τ) as the basis (twist of the torsion bar 16) is also common. Therefore, as long as there is no abnormality, the calculation results of both are also the same. Therefore, when an excessive current deviation that cannot occur in normal time occurs in any one of the microcomputers 21a and 21b, the control system of the first system and the control system of the second system configured as described above. It can be determined that some kind of abnormality has occurred. In this embodiment, when such an abnormality is detected, the power assist control is promptly stopped to achieve fail safe.

  More specifically, as shown in FIGS. 2 and 3, the power line 28b corresponding to the second phase motor coil 12b is detected by the second system microcomputer 21b having the second phase as the corresponding phase. Independent of the first current sensor 29b used, a second current sensor 35b is provided. Then, the first system microcomputer 21a detects the second-phase actual current value I_cos ′ that is the other phase, based on the output signal of the second current sensor 35b.

  In the microcomputer 21a, the second actual current value I_cos' is input to the subtractor 36a together with the second-phase current command value I_cos * calculated by the current command value calculation unit 26a, and further calculated by the subtractor 36a. The current deviation ΔI_cos ′ to be input is input to the abnormality determination unit 37a. Then, the abnormality determination unit 37a determines whether or not the current deviation ΔI_cos ′ of the other phase is an excessive value that cannot normally be taken, specifically, whether the current deviation ΔI_cos ′ exceeds a predetermined threshold (Ith). By determining whether or not, the abnormality determination is executed.

  Similarly, the power line 28a corresponding to the first phase motor coil 12a is independent of the first current sensor 29a used for current detection by the first system microcomputer 21a having the first phase as the corresponding phase. In addition, a second current sensor 35a is provided. Then, the second-system microcomputer 21b detects the actual current value I_sin ′ of the first phase that is the other phase, based on the output signal of the second current sensor 35b.

  In the microcomputer 21b, the first actual current value I_sin ′ is input to the subtractor 36b together with the first-phase current command value I_sin * calculated by the current command value calculation unit 26b, and further calculated by the subtractor 36b. The current deviation ΔI_sin ′ to be input is input to the abnormality determination unit 37b. Then, the abnormality determination unit 37b determines whether or not the current deviation ΔI_sin ′ of the other phase is an excessive value that cannot be normally obtained, specifically, whether the current deviation ΔI_sin ′ exceeds a predetermined threshold (Ith). By determining whether or not, the abnormality determination is executed.

  Further, in the present embodiment, when each abnormality determination unit 37a, 37b is determined to be abnormal (detected) by the abnormality determination, the PWM control output unit 32a and the second control output unit 32a provided in the first system microcomputer 21a. An abnormality detection signal Str indicating that an abnormality has occurred is output to both of the PWM control output units 32b provided in the microcomputer 21b of the system. In the present embodiment, the output of the abnormality detection signal Str to the PWM control output unit on the other phase side is executed in the form of transmission of status signals performed by the microcomputers 21a and 21b. In this embodiment, the power assist control is stopped by outputting a motor control signal indicating that each PWM control output unit 32a should stop the motor 12 based on the input of the abnormality detection signal Str. It is like that.

  That is, as shown in the flowchart of FIG. 4, each microcomputer 21a, 21b of the present embodiment determines whether or not an excessive current deviation has occurred in the other phase (step 101), and the excessive current deviation has occurred. If it is detected (step 101: YES), the abnormality detection signal Str is output as a status signal indicating the occurrence of abnormality to the microcomputers of other systems (step 102). Then, the motor control signal output mode is shifted to stop the power assist control (step 103).

  On the other hand, when it is determined in step 101 that there is no excessive current deviation on the other phase side (step 101: NO), it is subsequently determined whether or not there is an input of the abnormality detection signal Str from a microcomputer of another system. Determination is made (step 104). When the abnormality detection signal Str is input (step 104: YES), the motor control signal output mode is shifted to stop the power assist control (step 103).

  In step 104, when the abnormality detection signal Str is not input (step 104: NO), it is determined that the abnormality is normal, and the motor control signal in the normal mode is determined to continue the power assist control. The output is executed (step 105).

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) The motor 12 employs a brushless motor having two-phase motor coils 12a and 12b. The ECU 11 also includes a first system microcomputer 21a and a drive circuit 22a that perform sine energization on the first phase motor coil 12a, and a second system that performs cosine power supply on the second phase motor coil 12b. The microcomputer 21b and the drive circuit 22b are provided. Each of the microcomputers 21a and 21b independently generates a motor control signal for the corresponding phase by executing current feedback control for the corresponding phase, and excessive current deviations ΔI_sin ′ and ΔI_cos ′ in the other phases. Abnormality judgment is executed by monitoring the occurrence of

  According to the above configuration, when any abnormality occurs in the two control systems, particularly when an abnormality that affects the power assist control occurs in each of the microcomputers 21a and 21b, the abnormality is always , It will appear in the current deviation of the other phase. The microcomputers 21a and 21b monitor the current deviations ΔI_sin ′ and ΔI_cos ′ of the other phases with each other, more specifically, by monitoring the occurrence of excessive deviations, It is possible to detect that an abnormality has occurred in at least one of them. As a result, other abnormality determination control (monitoring circuit) related to each of the microcomputers 21a and 21b, such as the initial check of the memory at the time of startup as described above, is eliminated, and abnormality determination based on mutual monitoring of the other-phase current deviation as described above Can be substituted. As a result, not only can the start-up time be shortened, but also the cost can be reduced by reducing the processing capability required for each of the microcomputers 21a and 21b, and the failure rate can be reduced by reducing the circuit scale.

  (2) The power lines 28a and 28b of each phase are respectively used for the current detection of the other phase independently of the first current sensors 29a and 29b used by the microcomputers 21a and 21b to detect the current of the corresponding phase. Two current sensors 35a and 35b are provided.

  According to the above configuration, an abnormality (an abnormality in the current sensor main body constituting the current detection element and its signal wiring, etc.) generated in the process of detecting the actual current value (I_sin, I_cos, I_sin ′, I_cos ′) of each phase ) Also appears in the current deviation of the other phase. Therefore, the abnormality determination of the current detection element can be replaced with the abnormality determination based on the mutual monitoring of the other-phase current deviation as described above. As a result, the configuration is further simplified and the reliability is improved. be able to.

  (3) Each of the microcomputers 21a and 21b detects the steering torques τ1 and τ2 independently based on the two independent sensor signals Sa and Sb input from the torque sensor 14. Based on the steering torque τ (τ1, τ2), current command values I_sin * and I_cos * corresponding to the target assist force are calculated.

  According to the above configuration, an abnormality (an abnormality in the torque sensor 14 constituting the steering torque detection element and its signal wiring, etc.) generated in the process of detecting the steering torque τ (τ1, τ2) also appears as a current deviation. It becomes like this. Therefore, the abnormality determination of the steering torque detection element can be replaced with the abnormality determination based on the mutual monitoring of the other-phase current deviation as described above. As a result, the structure can be further simplified and the reliability can be improved. Can be planned.

  (4) The torque sensor 14 includes a torsion bar 16 provided in the middle of the column shaft 3a, and a sensor signal Sa that can detect the torsion of the torsion bar 16, that is, the steering torque τ transmitted through the steering shaft 3. And two independent sensor units 14a and 14b that output Sb.

  That is, the mechanical configuration of the torque sensor including the torsion bar is often extremely robust. Therefore, by using a torque sensor having only a double electrical configuration, the configuration can be simplified while ensuring reliability.

  (5) The motor 12 is provided with two rotation angle sensors 27a and 27b. The microcomputers 21a and 21b each independently detect the motor rotation angle θ (θ1, θ2) based on the output signals of the rotation angle sensors 27a and 27b.

  That is, the current command values I_sin * and I_cos * for each phase are calculated based on the basic assist control amount Ias * and the motor rotation angle θ. Therefore, according to the above configuration, abnormalities that occur in the process of detecting the motor rotation angle θ (θ1, θ2) (such as abnormalities in the rotation angle sensor main body and the signal wiring constituting the motor rotation angle detection element) are also obtained. It appears in the current deviation of the other phase. As a result, the abnormality determination of the detection element for the motor rotation angle can be replaced with the abnormality determination based on the mutual monitoring of the other-phase current deviation as described above. As a result, further simplification of the configuration and reliability can be achieved. Improvements can be made.

In addition, you may change the said embodiment as follows.
In the above embodiment, the present invention is embodied in a so-called column type EPS. However, the present invention is not limited to this, and a so-called pinion type or rack assist type EPS may be used.

  In the above-described embodiment, the power lines 28a and 28b of the respective phases have the current detection of the other phases independent of the first current sensors 29a and 29b used by the microcomputers 21a and 21b for detecting the current of the corresponding phase, respectively. The second current sensors 35a and 35b used for the above are provided. However, the present invention is not limited to this. For example, in the case where normal current detection is ensured, for example, there is a separate current sensor abnormality detection means, one current sensor is provided for each phase power line 28a, 28b. To do. That is, the second current sensor may be eliminated, and the microcomputers 21a and 21b may use a common value as the actual current values I_sin and I_cos of the respective phases. Even with such a configuration, it is possible to perform independent current feedback control in each phase and to perform abnormality detection based on mutual monitoring of other-phase current deviations.

  In the above embodiment, the torque sensor 14 including the two independent sensor units 14a and 14b that output the sensor signals Sa and Sb that can detect the steering torque τ is used, and each of the microcomputers 21a and 21b corresponds to the torque sensor 14. The steering torques τ1, τ2 are detected independently based on the sensor signals Sa, Sb. However, the present invention is not limited to this, and two independent torque sensors may be provided to input respective signals to the corresponding microcomputers. Further, if the reliability of steering torque detection is ensured, the microcomputers 21a and 21b may be configured to use a common value as the steering torque τ.

  In the above embodiment, the motor 12 is provided with the two rotation angle sensors 27a and 27b, and the microcomputers 21a and 21b are independently operated on the basis of the output signals of the rotation angle sensors 27a and 27b. The rotation angle θ (θ1, θ2) was detected. However, the present invention is not limited to this, and if the reliability of the motor rotation angle detection is ensured, the microcomputers 21a and 21b may use a common value as the motor rotation angle θ.

  Note that, if an abnormality of the entire system is determined by abnormality determination based on mutual monitoring of other-phase current deviations, it is desirable to adopt a configuration as shown in the above embodiment. That is, the microcomputers 21a and 21b are provided with the second current sensors 35a and 35b used for detecting the current of the other phase independently of the first current sensors 29a and 29b used for detecting the current of the corresponding phase. Further, the microcomputers 21a and 21b are configured to be capable of independently detecting the steering torque τ (τ1, τ2) and the motor rotation angle θ (θ1, θ2). As a result, the control system for the abnormality determination based on the current feedback calculation for executing the power assist control and the mutual monitoring of the other-phase current deviation is an independent dual system for each phase (FIG. 2 and FIG. 2). 3).

  By setting it as such a structure, all the abnormality which arose in the structure which becomes main in performing assist force provision will appear as an electric current deviation. As a result, it is possible to secure high reliability while simplifying the configuration by eliminating other abnormality determination control (monitoring circuit).

Next, technical ideas that can be grasped from the above embodiments will be described.
(A) The electric power steering apparatus according to claim 3, further comprising a torque sensor that outputs two independent sensor signals capable of detecting the steering torque based on torsion of a torsion bar provided in the middle of the steering shaft. An electric power steering device characterized by that. That is, the mechanical configuration of the torque sensor including the torsion bar is often extremely robust. Therefore, by using a torque sensor having only a double electrical configuration, the configuration can be simplified while ensuring reliability.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus (EPS), 2 ... Steering, 3 ... Steering shaft, 10 ... EPS actuator, 11 ... ECU, 12 ... Motor, 12a, 12b ... Motor coil, 14 ... Torque sensor, 14a, 14b ... Sensor unit , 16 ... Torsion bar, 21a, 21b ... Microcomputer, 22a, 22b ... Drive circuit, 23a, 23b ... Pre-driver, 25a, 25b ... Basic assist control unit, 26a, 26b ... Current command value calculation unit, 27a, 27b ... Rotation Angle sensor, 28a, 28b ... power line, 29a, 29b ... first current sensor, 30a, 30b ... subtractor, 31a, 31b ... F / B control unit, 32a, 32b ... PWM control output unit, 35a, 35b ... Second current sensor, 36a, 36b ... subtractor, 37a, 37b ... abnormality determination unit, Sa, S b ... sensor signal, τ (τ1, τ2) ... steering torque, θ (θ1, θ2) ... motor rotation angle, Ias * ... basic assist control amount, I_sin *, I_cos * ... current command value, I_sin, I_cos, I_sin ' , I_cos ′: actual current value, ΔI_sin, ΔI_cos, ΔI_sin ′, ΔI_cos ′: current deviation, Str: abnormality detection signal.

Claims (5)

A steering force assisting device for applying an assist force to the steering system using a motor as a drive source; and a control means for controlling the operation of the steering force assisting device, wherein the control means generates a motor torque corresponding to the assist force. In an electric power steering apparatus comprising: a control signal output means for outputting a motor control signal to be generated; and a drive circuit for supplying drive power based on the motor control signal to the motor.
The motor is a brushless motor having a two-phase motor coil,
The control means includes a control signal output means and a drive circuit of a first system for executing sine energization for the first phase motor coil, and a second for performing cosine energization for the second phase motor coil. System control signal output means and drive circuit,
Each control signal output means performs the current feedback control independently to generate the motor control signal for the corresponding phase, and performs abnormality determination by monitoring the occurrence of an excessive current deviation in the other phase. thing,
An electric power steering device. The electric power steering apparatus according to claim 1, wherein
A first current sensor used by each control signal output means for detecting a current of a corresponding phase; and a second current sensor used by each control signal output means for detecting a current of another phase;
An electric power steering device. In the electric power steering device according to claim 1 or 2,
Two independent sensor signals that can detect steering torque transmitted to the steering system are input to the control means,
Each of the control signal output means independently calculates a current command value based on the steering torque detected by the corresponding sensor signal;
An electric power steering device. In the electric power steering device according to any one of claims 1 to 3,
The first rotation angle sensor used by the control signal output means corresponding to the first phase to detect the motor rotation angle, and the second rotation angle sensor used by the control signal output means corresponding to the second phase to detect the motor rotation angle. And an electric power steering device characterized by being provided independently. In the electric power steering device according to any one of claims 1 to 4,
The control means stops power assist control for applying assist force to the steering system when it is determined abnormal by the abnormality determination;
An electric power steering device.

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