JP2012065416A - Motor controlling device and electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controlling device and an electric power steering device which are capable of suppressing generation of a torque ripple in the case of occurrence of an electric conduction defective phase during a high speed driving in particular, and of making delicate handle steering easy.SOLUTION: A CPU 17 comprises: a current command value calculating part 23 which calculates a d-axis current command value Id* and a q-axis current command value Iq*; and a motor control signal generating part 24 which generates a motor control signal by executing current feedback control in a d/q coordinate system based on these d-axis current command value Id* and q-axis current command value Iq*. The CPU 17 is provided with an abnormality determining part 31 capable of detecting the occurrence of the abnormality in the case of occurrence of electric conduction defection in any of phases of a motor 12, and in the case where the abnormality is detected, executes generating of the motor control signal by making two phases other than the electric conduction defective phase an electric conduction phase. Then, in the case where a vehicle speed which speed detecting means 16 detects becomes not less than a prescribed value, the q-axis current command value Iq* is decreased gradually.

Description

  The present invention relates to a motor control device and an electric power steering device.

  Conventionally, many motor control devices used in an electric power steering device (EPS) or the like have any phase of the motor (either U, V, or W) due to a disconnection of a power supply line or a contact failure of a drive circuit. An abnormality detection means is provided that can detect the occurrence of the abnormality when a current-carrying failure occurs. And when generation | occurrence | production of the said abnormality is detected, the structure which stops motor control rapidly and aims at fail safe is common.

  However, in EPS, as the motor control stops, the steering characteristics change greatly. That is, a greater steering force is required for the driver to perform an appropriate steering operation. Based on this point, conventionally, there is a motor control device that continues motor control using two phases other than the current-carrying failure phase as a current-carrying phase even when the occurrence of a current-carrying failure phase is detected as described above (for example, Patent Document 1). As a result, the application of assist force to the steering system can be continued, and an increase in the driver's burden associated with fail-safe can be avoided.

WO2005 / 091488

However, as in the above-described conventional example, when a current-carrying failure phase occurs, the motor is set with two phases other than the current-carrying failure occurrence phase as current-carrying phases (the example shown in FIG. When the control is continued, the steering feeling is inevitably deteriorated due to the torque ripple generated at the motor rotation angles of 90 degrees and 270 degrees as shown in FIG.

  In addition, during high-speed driving, the higher the vehicle speed, the narrower the steering angle range of the steering wheel. When motor control is continued using the two phases as energized phases, the angle at which motor torque cannot be output to the steering angle range of the steering wheel If there is a range, it is difficult to handle the steering wheel delicately. In this respect, there is still room for improvement.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to suppress the occurrence of torque ripple in the occurrence of a poorly energized phase, particularly during high-speed traveling, and facilitate delicate steering of the steering wheel. An object of the present invention is to provide a motor control device and an electric power steering device that can be used.

  In order to solve the above problem, the invention described in claim 1 is a motor control signal output means (17) for outputting a motor control signal, and supplies three-phase drive power to the motor based on the motor control signal. A motor drive circuit (18), and the motor control signal output means (17) calculates a d / q coordinate system d-axis current command value and a q-axis current command value as a current command value. The calculation means (23) converts the detected phase current values of the motor into the d-axis current value and the q-axis current value of the d / q coordinate system, and calculates the d-axis current value and the q-axis current value. Motor control signal generation means (24) for generating the motor control signal by executing feedback control so as to follow the d-axis current command value and the q-axis current command value, and any one of the motors There is an energization failure in the phase of An abnormality detection means (31) capable of detecting the occurrence of the abnormality when the abnormality occurs, and when the abnormality is detected, an output of the motor control signal having a phase other than the abnormality occurrence phase as an energized phase; The motor control device to be executed includes vehicle speed detection means (16) for detecting a vehicle speed, and the current command value calculation means (23) rotates at a predetermined rotation according to the abnormality occurrence phase when the abnormality is detected. Except for a corner, the d-axis current command value is calculated so that the q-axis current corresponding to the q-axis current command value is generated, and according to the vehicle speed detected by the vehicle speed detection means (16), The gist is to correct the q-axis current command value.

According to the above configuration, the q-axis current command value can be corrected according to the vehicle speed.
As a result, even when a poorly energized phase occurs, generation of torque ripple can be suppressed according to the required vehicle speed, and delicate steering can be facilitated.

  According to a second aspect of the present invention, when the current command value calculating means (23) detects the abnormality and the vehicle speed detected by the vehicle speed detecting means (16) exceeds a predetermined vehicle speed value, the current command value calculating means (23) The gist is to gradually reduce the q-axis current command value.

According to the above configuration, the q-axis current command value can be gradually decreased when the vehicle speed becomes equal to or higher than a predetermined value.
As a result, even when a poorly energized phase occurs, if the vehicle speed is higher than the specified value, the q-axis current command value becomes very small, suppressing torque ripple and facilitating delicate steering. Can be.

The gist of the invention described in claim 3 is an electric power steering device including the motor control device according to any one of claims 1 and 2.
According to the above configuration, even when a poorly energized phase is generated, the generation of torque ripple can be suppressed according to the vehicle speed, and the application of the assist force can be continued while maintaining a good steering feeling. It becomes like this.

  According to the present invention, it is possible to provide a motor control device and an electric power steering device that can suppress the occurrence of torque ripple particularly during high-speed traveling in the occurrence of a poorly energized phase, and can facilitate delicate steering. it can.

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 the structure of an abnormality determination part. The flowchart figure which shows the process sequence of an electricity supply failure phase detection. The block diagram which shows the structure of an electric current command value calculating part. Current command value Iq * calculation unit assist map Vehicle speed gain map of Iq ** correction calculation unit of current command value Iq * calculation unit The flowchart figure which shows the process sequence of the Iq ** correction | amendment calculating part of an electric current command value Iq * calculating part. The flowchart figure which shows the process sequence of an electric current command value Id * calculating part. The q-axis current figure at the time of the conventional two-phase drive.

Hereinafter, an embodiment of the present invention embodied in a column-type electric power steering apparatus (hereinafter referred to as EPS) will be described with reference to the drawings.
As shown in FIG. 1, in the EPS 1 of the present 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 8, an intermediate shaft 9, and a pinion shaft 10. 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. Is changed.

  Further, the EPS 1 includes an EPS actuator 13 that applies an assist force for assisting a steering operation to the steering system, and an ECU 11 that serves as a control unit that controls the operation of the EPS actuator 13.

  The EPS actuator 13 of the present embodiment is a column type EPS actuator, and the motor 12 that is a driving source thereof is drivingly connected to the column shaft 8 via a speed reduction mechanism 14. The EPS actuator 13 applies the motor torque as an assist force to the steering system by decelerating the rotation of the motor 12 by the speed reduction mechanism 14 and transmitting it to the column shaft 8.

  A vehicle speed sensor 16, a torque sensor 15, and a motor rotation angle sensor 22 are connected to the ECU 11. The ECU 11 detects the vehicle speed V, the steering torque τ, and the motor rotation angle θ based on the output signals of these sensors. For example, the torque sensor 15 of the present embodiment is a twin resolver type torque sensor in which a pair of resolvers are provided at both ends of a torsion bar (not shown). Further, the ECU 11 calculates a target assist force based on each detected state quantity, and controls the operation of the EPS actuator 13, that is, the assist force applied to the steering system through the supply of drive power to the motor 12. To do.

Next, an electrical configuration in the EPS 1 of the present embodiment will be described.
FIG. 2 is a control block diagram of the EPS 1 of the present embodiment. As shown in the figure, the EPS 1 includes an ECU 11 and a motor 12. The motor 12 is a brushless motor and has a motor rotation angle sensor 22 for detecting the motor rotation angle θ. The ECU 11 energizes the motor 12, a CPU 17 (motor control signal output means) that outputs a motor control signal, a motor drive circuit 18 that supplies three-phase drive power to the motor 12 based on the motor control signal, and the motor 12. Current sensors 21u, 21v, 21w for detecting each phase current value Iu, Iv, Iw are provided. The motor drive circuit 18 is a known PWM inverter in which three arms corresponding to each phase are connected in parallel with a pair of switching elements (power MOSFET or the like) connected in series as a basic unit (arm).

  The CPU 17 detects the phase current values Iu, Iv, Iw and the motor rotation angle θ of the motor 12 detected based on the output signals of the sensors 21u, 21v, 21w, 22, 15, 16 and the steering torque τ, And current feedback control based on the vehicle speed V. Specifically, the CPU 17 outputs to the motor drive circuit 18 a motor control signal that defines the on-duty ratio of each switching element constituting the motor drive circuit 18. When the motor control signal is applied, in the motor drive circuit 18, each switching element is turned on / off in response to the motor control signal. As a result, the motor drive circuit 18 generates three-phase motor drive power based on the power supply voltage of a battery (not shown) and outputs the generated motor drive power to the motor 12.

  Each control block shown below is a calculation process realized by a computer program executed by the CPU 17. The CPU 17 detects each of the above state quantities at a predetermined sampling period, and generates a motor control signal by executing each arithmetic process shown in the following control blocks every predetermined period.

  As shown in FIG. 2, the CPU 17 has a current command value calculation unit 23 (current command value calculation means) that calculates a current command value for controlling the motor 12, and a motor control signal generation unit 24 (that generates the motor control signal). Motor control signal generating means).

The structure of the electric current command value calculating part 23 is demonstrated based on FIG.
The current command value calculation unit 23 calculates the d-axis current command value Id * based on the motor rotation angle θ and the X phase (X = U, V, W) energization normal / abnormal determination state flag Stmx (described later). Current command value Id * calculation unit 23a, steering torque τ detected by the torque sensor 15, vehicle speed V detected by the vehicle speed sensor 16, and the X phase (X = U, V, W) energization normal / abnormal judgment state Based on the flag Stmx, a current command value Iq * calculation unit 23b that calculates the q-axis axis current command value Iq * is provided.

  The current command value Iq * calculation unit 23b corrects the assist map 23c shown in FIG. 6 and the current command value Iq ** output from the assist map 23c by a vehicle speed gain map 23e (described later) in FIG. A current command value Iq ** correction calculation unit 23d.

  The d-axis current command value Id * and the q-axis current command value Iq * calculated by the current command value calculation unit 23 are output to the motor control signal generation unit 24. On the other hand, the motor control signal generation unit 24 includes the d-axis current command value Id * and the q-axis axis current command value Iq * calculated by the current command value calculation unit 23, and the current sensors 21u, 21v, and 21w. The detected phase current values Iu, Iv, Iw and the motor rotation angle θ detected by the rotation angle sensor 22 are input. The motor control signal generator 24 generates a motor control signal by executing current feedback control in the d / q coordinate system based on the phase current values Iu, Iv, Iw and the motor rotation angle θ. .

  That is, in the motor control signal generation unit 24, the phase current values Iu, Iv, and Iw are input to the three-phase / two-phase conversion unit 25 together with the motor rotation angle θ, and the three-phase / two-phase conversion unit 25 performs d / It is converted into a d-axis current value Id and a q-axis current value Iq in the q coordinate system. Further, the q-axis current command value Iq * output from the current command value calculator 23 is input to the subtractor 26q together with the q-axis current value Iq, and the d-axis current command value Id * is combined with the d-axis current value Id. Input to the subtractor 26d.

  In this embodiment, the current command value calculation unit 23 normally outputs zero (Id * = 0) as the d-axis current command value Id *. The d-axis current deviation ΔId and the q-axis current deviation ΔIq calculated in the subtracters 26d and 26q are input to the corresponding F / B control units 27d and 27q, respectively. In each of the F / B control units 27d and 27q, the d-axis current command value Id * and the q-axis current command value Iq * output from the current command value calculation unit 24 are the actual d-axis current value Id and Feedback control for following the q-axis axis current value Iq is performed.

  Specifically, the F / B control units 27d and 27q multiply the input d-axis current deviation ΔId and the predetermined F / B gain (PI gain) of the q-axis current deviation ΔIq to obtain a d-axis voltage command. The value Vd * and the q-axis voltage command value Vq * are calculated. The d-axis voltage command value Vd * and the q-axis voltage command value Vq * calculated by the F / B control units 27d and 27q are input to the two-phase / three-phase conversion unit 28 together with the rotation angle θ. The two-phase / three-phase conversion unit 28 converts the voltage into the three-phase voltage command values Vu *, Vv *, and Vw *.

  The voltage command values Vu *, Vv *, and Vw * calculated in the two-phase / three-phase conversion unit 28 are input to the PWM conversion unit 30. In the PWM conversion unit 30, the voltage command values Vu *, Vv DUTY command values αu, αv, αw corresponding to *, Vw * are generated. The motor control signal generator 24 generates a motor control signal having an on-duty ratio indicated by each phase DUTY command value αu, αv, αw, and the CPU 17 sends the motor control signal to the motor drive circuit 18. The operation of the motor drive circuit 18, that is, the supply of drive power to the motor 12, is controlled by outputting to each of the switching elements (the gate terminals).

(Control mode when an abnormality occurs)
Next, a control mode when an abnormality occurs in the ECU of the present embodiment will be described.
As shown in FIG. 2, in the ECU 11 of the present embodiment, the CPU 17 is provided with an abnormality determination unit 31 (abnormality detection means) for specifying the abnormality mode when any abnormality occurs in the EPS 1. Yes. Then, the ECU 11 changes the control mode of the motor 12 in accordance with the abnormality mode specified (determined) by the abnormality determination unit 31.

  The abnormality determination unit 31 receives the phase current values Iu, Iv, Iw and the rotational angular velocity ω of the motor 12 and the DUTY command values αu, αv, αw of each phase. Then, the abnormality determination unit 31 determines the abnormality of the torque sensor 15 and the abnormality in the power supply system to the motor 12 based on these state quantities, specifically, the occurrence of overcurrent or the power line (motor coil). The occurrence of a poorly energized phase due to contact failure of the motor drive circuit 18 or the like.

  More specifically, as shown in FIG. 3, the abnormality determining unit 31 includes an X-phase energization abnormality determining unit 31a for determining an X-phase (X = U, V, W) energization abnormality and an X-phase energization abnormality determining unit 31a. The X-phase energization normality / abnormality determination storage unit 31b stores the determined X-phase energization normality / abnormality determination results.

  For example, the X-phase energization normality / abnormality determination storage unit 31b stores the contents of the U-phase energization normality / abnormality determination state flag Stmu at the memory address 100 (if the state flag Stmu is “0”, the U-phase energization normal / abnormality determination storage unit 31b Is a normal state and the state flag Stmu is “1”, the U-phase energization indicates an abnormal state). Similarly, the contents of the V-phase energization normal / abnormal determination state flag Stmv are stored at the memory address 101, and the contents of the W-phase energization normal / abnormal determination state flag Stmw are stored at the memory address 102.

Next, an X-phase energization failure determination method performed by the X-phase energization abnormality determination unit 31a will be described.
For example, detection of the occurrence of an energization failure phase is performed when the X-phase phase current value Ix is equal to or less than a predetermined current value Ith (| Ix | ≦ Ith) and the rotational angular velocity ω is within the disconnection determination target range (| ω | ≦ ω0). Whether or not the state in which the DUTY command value αx corresponding to the phase is not in the predetermined range (αLO ≦ αx ≦ αHI) corresponding to the predetermined current value Ith and the predetermined rotational angular velocity value ω0 that defines the determination target range is continued in some cases. It is done by.

  In this case, the predetermined current value Ith that is the threshold value of the X-phase current value Ix is set to a value near “0”, and the predetermined rotational angular velocity value ω0 that is the threshold value of the rotational angular velocity ω is the motor base speed ( Is set to a value corresponding to the maximum number of revolutions). The DUTY threshold values (αLO, αHI) relating to the DUTY command value αx are set to a value smaller than a lower limit value that can be taken by the DUTY command value αx and a value larger than the upper limit value in normal control.

  That is, as shown in the flowchart of FIG. 4, the X-phase energization abnormality determination unit 31a determines whether or not the detected X-phase current value Ix (absolute value thereof) is equal to or less than a predetermined current value Ith (step 101). ), If it is equal to or smaller than the predetermined current value Ith (| Ix | ≦ Ith, Step 101: YES), it is subsequently determined whether or not the rotational angular velocity ω (the absolute value thereof) is equal to or smaller than the predetermined rotational angular velocity value ω0. (Step 102). When the rotational angular velocity ω is equal to or smaller than the predetermined rotational angular velocity value ω0 (| ω | ≦ ω0, step 102), whether or not the DUTY command value αx is within the predetermined range (αLO ≦ αx ≦ αHI). (Step 103), if it is not within the predetermined range (step 103: NO), it is determined that an energization failure has occurred in the X phase, and the X phase energization normality / abnormality determination storage unit 31b stores “ 1 "is written (X-phase conduction failure, Stmx = 1, step 104).

  When the phase current value Ix is larger than the predetermined current value Ith (| Ix |> Ith, Step 101: NO), the X-phase energization abnormality determining unit 31a is when the rotational angular velocity ω is larger than the predetermined rotational angular velocity value ω0. (| Ω |> ω0, step 102: NO) or when the DUTY command value αx is within the predetermined range (αLO ≦ αx ≦ αHI, step 103: YES), it is determined that the X phase is normal. Then, “0” is written in the X-phase energization normality / abnormality determination storage unit 31b (X-phase normality, Stmx = 0, step 105).

  That is, when an energization failure (disconnection) occurs in the X phase (any one of the U, V, and W phases), the X phase current value Ix of the phase is “0”. Here, in the case where the X-phase phase current value Ix is “0” or “a value close to 0”, there are the following two cases other than the occurrence of the disconnection.

When the rotational angular speed of the motor reaches the base speed (maximum rotational speed) When the current command itself is substantially “0” Based on this point, in this embodiment, first, the phase current of the X phase to be determined By comparing the value Ix with the predetermined current value Ith, it is determined whether or not the phase current value Ix is “0”. Then, it is determined whether or not the two cases where the phase current value Ix is “0” or “a value close to 0” except when the wire is disconnected. It is determined that a disconnection has occurred.

  That is, when the extreme DUTY command value αx is output even though the rotational angular velocity ω (basicity) is not such that the phase current value Ix is equal to or less than the predetermined current value Ith near “0”, It can be determined that an energization failure has occurred in the X phase. And in this embodiment, the abnormality determination part 31 becomes a structure which identifies the phase in which the conduction failure generate | occur | produced by performing the said determination about each phase of U, V, and W.

  Although not shown in the flowchart of FIG. 4 for convenience of explanation, the above determination is made on the assumption that the power supply voltage is equal to or higher than a specified voltage necessary for driving the motor 12. Then, the final abnormality detection determination is performed based on whether or not the state in which it is determined in the predetermined step 104 that an energization failure has occurred has continued for a predetermined time or more.

  In the present embodiment, the ECU 11 switches the control mode of the motor 12 based on the result of the abnormality determination in the abnormality determination unit 31. Specifically, the abnormality determination unit 31 outputs an abnormality determination result including the above-described failure of energization as an X-phase (X = U, V, W) energization normal / abnormality determination state flag Stmx, and a current command The value calculator 23 and the motor control signal generator 24 calculate the d-axis current command value Id * and the q-axis axis current command value Iq * according to the input X-phase energization normal / abnormal determination state flag Stmx, Generate motor control signals. Thereby, the control mode of the motor 12 in the CPU 11 is switched.

  More specifically, the ECU 11 of the present embodiment is a “normal control mode” that is a normal control mode, and a “assist stop mode” that is a control mode when an abnormality that should stop driving the motor 12 occurs. ”And“ two-phase drive mode ”, which is a control mode in the case where an energization failure occurs in any of the phases of the motor 12, is roughly divided into three control modes. When the X-phase energization normal / abnormal determination state flag Stmx output from the abnormality determination unit 31 corresponds to “normal control mode, Stmx = 0”, the current command value calculation unit 23 and the motor control signal generation The unit 24 calculates the normal d-axis current command value Id * and the q-axis current command value Iq * as described above, and generates a motor control signal.

  On the other hand, when the X-phase energization normal / abnormal determination state flag Stmx output from the abnormality determination unit 31 is “assist stop mode, two or more phases of Stmx = 1”, the current command value calculation unit 23 and the motor control signal generation The unit 24 calculates the d-axis current command value Id * and the q-axis current command value Iq * and generates a motor control signal in order to stop driving the motor 12.

  Further, in the “assist stop mode”, the output of the motor 12 is gradually reduced in addition to immediately stopping the driving of the motor 12. That is, there is a case where the assist force is gradually reduced and then stopped. In this case, the motor control signal generator 24 gradually reduces the value (absolute value) of the q-axis current command value Iq * that is output. Then, after the motor 12 is stopped, the CPU 11 opens each switching element constituting the motor drive circuit 18 and opens a power relay (not shown).

  Next, when the X-phase energization normal / abnormal determination state flag Stmx output from the abnormality determination unit 31 is “two-phase drive mode, one phase of Stmx = 1”, the X-phase energization normal / abnormal determination state flag Stmx. Includes information for specifying a current-carrying failure occurrence phase. When the X-phase energization normality / abnormality determination state flag Stmx output from the abnormality determination unit 31 corresponds to this “two-phase drive mode”, the motor control signal generation unit 24 selects a phase other than the energization failure occurrence phase. Generation of a motor control signal having two phases as energized phases is executed.

The current command value calculation unit 23 that switches between the three control modes will be described.
As described above, the current command value calculation unit 23 includes the current command value Iq ** correction calculation unit 23d in the current command value Iq * calculation unit 23b. The processing of the current command value Iq ** correction calculation unit 23d will be described in detail based on the flowchart of FIG.

  As shown in the flowchart of FIG. 8, the current command value Iq ** correction calculation unit 23d first determines the vehicle speed V, the X-phase energization normal / abnormal determination state flag Stmx, and the current command value Iq ** output from the assist map 23c. Read (step 201). Subsequently, it is determined whether or not the X-phase energization normal / abnormal determination state flag Stmx is “0” (step 202).

  Next, when it is determined in step 202 that an energization failure occurrence phase has occurred (step 202: NO), it is determined whether or not the energization failure occurrence phase is the U phase (step 203). If the energization failure occurrence phase is the U phase (step 203: YES), it is further determined whether or not the V phase is an energization failure occurrence phase (step 204). If the V phase is also a current-carrying failure occurrence phase (step 204: YES), it is further determined whether or not the W-phase is a current conduction failure occurrence phase (step 205). If the W phase is also a current-carrying failure occurrence phase (step 205: YES), it is determined that the current conduction failure has occurred in all three phases, the “assist stop mode” is set, and the current command value Iq * = 0 is output (step 206). To finish the process.

  If the W phase is not a current-carrying failure occurrence phase (step 205: NO), it is determined that a current conduction failure has occurred in the U-phase and the V-phase, the “assist stop mode” is set, and the current command value Iq * = 0 Is output (step 206), and the process ends.

  If the V phase is not a current-carrying failure occurrence phase (step 204: NO), it is subsequently determined whether the W-phase is a current conduction failure occurrence phase (step 207). Then, if the W phase is an energization failure occurrence phase (step 207: YES), it is determined that energization failure has occurred in the U phase and the W phase, the “assist stop mode” is set, and the current command value Iq * = 0 is set. Output (step 206) and finish the process.

  Next, when the W phase is not a current-carrying failure occurrence phase (step 207: NO), it is determined that only the U-phase has a current conduction failure, and the vehicle speed gain G is determined to correspond to the “two-phase drive mode” (step 208). . As shown in FIG. 7, the vehicle speed gain G is 1 when the vehicle speed is less than or equal to a predetermined vehicle speed value V0, and the vehicle speed gain G when the vehicle speed is greater than or equal to the predetermined vehicle speed value V0. G gradually decreases and converges to zero. When the vehicle speed gain G is determined based on the vehicle speed, the "two-phase drive mode" is set, and the current command value Iq * is corrected by multiplying the current command value Iq ** obtained from the assist map unit 23c by the determined vehicle speed gain G. (Step 209).

  Next, when the U-phase is not an energization failure occurrence phase (step 203: NO), it is determined whether or not the V-phase is an energization failure occurrence phase (step 210). If the V phase is an energization failure occurrence phase (step 210: YES), then it is determined whether the W phase is an energization failure occurrence phase (step 211). If the W phase is also a current-carrying failure generation phase (step 211: YES), it is determined that a power-supply failure has occurred in the two phases of V phase and W phase, the “assist stop mode” is set, and the current command value Iq * = 0 is set. Output (step 206) and finish the process.

  Next, when the W-phase is not a current-carrying failure occurrence phase (step 211: NO), it is determined that only the V-phase has a current-carrying failure, and the vehicle speed gain G is determined to correspond to the “two-phase drive mode” (step 208). . When the vehicle speed gain G is determined based on the vehicle speed, the "two-phase drive mode" is set, and the current command value Iq * is corrected by multiplying the current command value Iq ** obtained from the assist map unit 23c by the determined vehicle speed gain G. (Step 209).

  Next, when the V phase is not an energization failure occurrence phase (step 210: NO), it is determined whether or not the W phase is an energization failure occurrence phase (step 212). Then, if the W phase is an energization failure occurrence phase (step 212: YES), it is determined that only the W phase has energization failure, and the vehicle speed gain G is determined to correspond to the “two-phase drive mode” (step 208). . When the vehicle speed gain G is determined based on the vehicle speed, the "two-phase drive mode" is set, and the current command value Iq * is corrected by multiplying the current command value Iq ** obtained from the assist map unit 23c by the determined vehicle speed gain G. (Step 209).

  Next, when the W phase is not a current-carrying failure occurrence phase (step 212: NO), it is determined that all phases are normal, the “normal control mode” is set, and the current command value Iq ** obtained from the assist map unit 23c is used as the current command. Output as a value Iq * (step 213), and the process ends.

  As described above, the current command value calculation unit 23 has the current command value Id * calculation unit 23a that calculates the d-axis current command value Id * together with the current command value Iq * calculation unit 23b. The current command value Id * calculating unit 23a is also selected by the X-phase energization normal / abnormal determination state flag Stmx. The processing of the current command value Id * calculation unit 23a will be described in detail based on the flowchart of FIG.

  As shown in the flowchart of FIG. 9, the current command value Id * calculation unit 23a is first output from the motor rotation angle θ, the X-phase energization normal / abnormal determination state flag Stmx, and the current command value Iq ** correction calculation unit 23d. The current command value Iq * is read (step 301). Subsequently, it is determined whether or not the X-phase energization normal / abnormal determination state flag Stmx is “0” (step 302).

  Next, when it is determined in step 302 that an energization failure occurrence phase has occurred (step 302: NO), it is determined whether or not the energization failure occurrence phase is the U phase (step 303). If the energization failure occurrence phase is the U phase (step 303: YES), it is further determined whether the V phase is an energization failure occurrence phase (step 304). If the V phase is also a current-carrying failure occurrence phase (step 304: YES), it is further determined whether or not the W-phase is a current conduction failure occurrence phase (step 305). If the W phase is also a current-carrying failure generation phase (step 305: YES), it is determined that a power distribution failure has occurred in all three phases, and the process ends as “assist stop mode” (step 306).

  Further, when the W phase is not a current-carrying failure occurrence phase (step 305: NO), it is determined that a current conduction failure has occurred in the U-phase and the V-phase, and the processing ends as “assist stop mode” (step 306).

  If the V phase is not a current-carrying failure occurrence phase (step 304: NO), it is subsequently determined whether the W-phase is a current conduction failure occurrence phase (step 307). Then, if the W phase is an energization failure occurrence phase (step 307: YES), it is determined that energization failure has occurred in the two phases of the U phase and the W phase, and the process ends as “assist stop mode” (step 306).

  Next, when the W phase is not a current-carrying failure occurrence phase (step 307: NO), it is determined that only the U-phase has a current conduction failure, and the current command value Id * is calculated in order to correspond to the “two-phase drive mode” (step 307). 308: Id * = Iq * · tan θ). When the current command value Id * is calculated, the “two-phase drive mode” is set, and the process ends (step 309).

  Next, when the U-phase is not an energization failure occurrence phase (step 303: NO), it is determined whether the V-phase is an energization failure occurrence phase (step 310). If the V phase is a current-carrying failure occurrence phase (step 310: YES), then it is determined whether the W-phase is a current conduction failure occurrence phase (step 311). If the W phase is also a current-carrying failure generation phase (step 311: YES), it is determined that a power-supply failure has occurred in the two phases of the V phase and the W phase, and the processing ends as the “assist stop mode” (step 306).

  Next, when the W-phase is not a current-carrying failure occurrence phase (step 311: NO), it is determined that only the V-phase has a current-carrying failure, and the current command value Id * is calculated in order to correspond to the “two-phase drive mode” (step 31). 312: Id * = Iq * · tan (θ-2π / 3)). When the current command value Id * is calculated, the “two-phase drive mode” is set, and the process ends (step 309).

  Next, when the V-phase is not an energization failure occurrence phase (step 310: NO), it is determined whether or not the W-phase is an energization failure occurrence phase (step 313). If the W phase is a current-carrying failure occurrence phase (step 313: YES), it is determined that only the W-phase has a current conduction failure, and the current command value Id * is calculated in order to correspond to the “two-phase drive mode” (step 314: Id * = Iq * · tan (θ + 2π / 3)). When the current command value Id * is calculated, the “two-phase drive mode” is set, and the process ends (step 309).

  Next, if the W phase is not a current-carrying failure occurrence phase (step 313: NO), it is determined that all phases are normal, the “normal control mode” is set, Id * = 0 is output, and the process ends (step 315).

As described above, according to the present embodiment, the following operations and effects can be obtained.
The CPU 17 calculates a d command current command value Id * and a q command current command value Iq *, a current command value calculation unit 23, and based on the d command current command value Id * and the q command current command value Iq *, d A motor control signal generation unit 24 that generates a motor control signal by executing current feedback control in the / q coordinate system. In addition, the CPU 17 includes an abnormality determination unit 31 that can detect the occurrence of an abnormality when an energization failure occurs in any phase of the motor 12, and when the abnormality is detected, the energization failure occurrence phase is detected. The motor control signal is generated using the other two phases as energized phases. At this time, the CPU 17 removes a predetermined rotation angle corresponding to the current-carrying failure occurrence phase, and generates a d-axis current command value Id so that a q-axis current value Iq corresponding to the q-axis current command value Iq * is generated. Calculate *. Further, when the vehicle speed V detected by the vehicle speed detection means becomes equal to or higher than the predetermined vehicle speed value V0, the q-axis current command value Iq * is gradually decreased.

  According to the above configuration, it is possible to suppress the generation of torque ripple even during the occurrence of a poorly energized phase, and it is possible to suppress the generation of assist torque as much as possible without feeling uncomfortable, especially during high-speed traveling. As a result, it is possible to suppress the occurrence of torque ripple in the entire steering state in the occurrence of a poorly energized phase and facilitate delicate steering of the steering wheel.

In addition, you may change this embodiment as follows.
In the present embodiment, the present invention is embodied in an electric power steering device (EPS), but may be embodied in a motor control device used for applications other than EPS.

In the present embodiment, the current command value Iq * is corrected by multiplying the current command value Iq ** obtained from the assist map 23c by the determined vehicle speed gain G. When the vehicle speed V becomes equal to or higher than the predetermined vehicle speed value V0, the vehicle speed gain G gradually decreases and converges to zero, so that the generation of the assist torque can be suppressed as much as possible without feeling uncomfortable, especially during high speed traveling. I did it. However, the method of suppressing the generation of the assist torque during high-speed driving as much as possible is not limited to this. For example, an assist map (not shown) in which the high-speed area of the assist map 23c in FIG. Of course, the assist map 23c may be used by switching the assist map in the normal control mode and the assist map in the two-phase drive mode.

1: Electric power steering device (EPS), 2: Steering,
3: Steering shaft, 4: Rack and pinion mechanism, 5: Rack shaft,
6: Tie rod, 7: Steering wheel, 8: Column shaft, 9: Intermediate shaft, 10: Pinion shaft, 11: ECU, 12: Motor, 13: EPS actuator, 14: Deceleration mechanism, 15: Torque sensor, 16: Vehicle speed sensor, 17: CPU,
18: motor drive circuit, 21u, 21v, 21w: current sensor, 22: motor rotation angle sensor, 23: current command value calculation unit, 23a: current command value Id * calculation unit,
23b: current command value Iq * calculation unit, 23c: assist map,
23d: current command value Iq ** correction calculation unit, 23e: vehicle speed gain map,
24: Motor control signal generation unit, 25: 3-phase / 2-phase conversion unit, 26d, 26q: subtractor,
27d, 27q: F / B control unit, 28: 2-phase / 3-phase conversion unit, 30: PWM conversion unit,
31: Abnormality determination unit, 31a: X-phase energization abnormality determination unit,
31b: X-phase energization normality / abnormality determination storage unit,
V: vehicle speed, τ: steering torque, θ: motor rotation angle,
Iu, Iv, Iw: current value of each phase, Iq *: q-axis current command value, Id *: d-axis current command value,
Id: d-axis current value, Iq: q-axis current value, ΔId: d-axis current deviation, ΔIq: q-axis current deviation,
Vd *: d-axis voltage command value, Vq *: q-axis voltage command value,
Vu *, Vv *, Vw *: each phase voltage command value, αu, αv, αw: each phase DUTY command value,
αx: X-phase DUTY command value, αLO, αHI: DUTY threshold, G: vehicle speed gain,
V0: predetermined vehicle speed value, Ix: X-phase current value, Ith: predetermined current value,
ω: rotational angular velocity, ω0: predetermined rotational angular velocity value, δ: triangular wave (carrier wave),
Stmx: X phase (X = U, V, W) energization normal / abnormal judgment state flag,
Stmu: U-phase energization normal / abnormal judgment state flag,
Stmv: V-phase energization normal / abnormal judgment status flag,
Stmw: W phase energization normal / abnormal judgment status flag

Claims (3)

Motor control signal output means for outputting a motor control signal;
A drive circuit for supplying three-phase drive power to the motor based on the motor control signal, wherein the motor control signal output means includes a d / q coordinate system d-axis current command value and q Current command value calculating means for calculating the shaft current command value;
Each phase current value of the detected motor is converted to a d-axis current value and a q-axis current value in the d / q coordinate system, and the d-axis current value and the q-axis current value are calculated as the calculated d-axis current command. Motor control signal generating means for generating the motor control signal by executing feedback control to follow the value and the q-axis current command value,
An abnormality detecting means capable of detecting the occurrence of the abnormality when a current-carrying failure occurs in any phase of the motor;
When the abnormality is detected, the motor control device executes the output of the motor control signal with a phase other than the abnormality occurrence phase as an energized phase,
While equipped with vehicle speed detection means for detecting the vehicle speed,
The current command value calculation means is configured to generate the q-axis current corresponding to the q-axis current command value except for a predetermined rotation angle corresponding to the abnormality occurrence phase when the abnormality is detected. While calculating the current command value,
A motor control device, wherein the q-axis current command value is corrected according to a vehicle speed detected by the vehicle speed detection means. The current command value calculating means gradually reduces the q-axis current command value when the abnormality is detected, and the vehicle speed detected by the vehicle speed detection means is equal to or higher than a predetermined vehicle speed value;
The motor control device according to claim 1.   An electric power steering apparatus comprising the motor control apparatus according to claim 1.

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