JP5703595B2 - Motor control device and electric power steering device - Google Patents

Description

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

  In general, a motor control device that controls the operation of a motor through the supply of drive power has a function of detecting the occurrence of energization failure in the power supply path. In other words, in a motor control device that controls a brushless motor that rotates based on three-phase (U, V, W) driving power, the target command current value indicates an energized state. When any of the phase current values is a value indicating a non-energized state, it can be determined that an energization failure (disconnected state) has occurred in the phase (see, for example, Patent Document 1). Further, by adding a rotational angular velocity condition and eliminating the high-speed rotation that prevents the current from flowing into the motor coil due to the influence of the counter electromotive voltage, it is possible to detect the energization failure more accurately ( For example, see Patent Document 2).

International Publication No. 2006/112033 Pamphlet JP 2007-224028 A JP 2010-11709 A

  However, some motor control devices that control brushless motors supply the drive power without detecting the motor rotation angle (and rotation angular velocity) (see, for example, Patent Document 3). For such a device that performs so-called resolverless control, the rotational angular velocity condition cannot be added, and there is a problem that improvement in detection accuracy cannot be expected, and there is still room for improvement in this respect. It was a thing.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a motor control capable of accurately detecting the occurrence of a conduction failure in the power supply path without detecting the rotational angular velocity. It is providing a device and an electric power steering device.

  In order to solve the above problems, the invention according to claim 1 is a motor control signal output means for outputting a motor control signal, and a drive circuit for supplying three-phase drive power to the motor based on the motor control signal. And an abnormality detecting means for detecting the occurrence of an energization failure in the power supply path to the motor by monitoring the current value of each phase, the abnormality detecting means should be in an energized state When the current value of the phase is a value indicating a non-energized state, and the current value of the other phase is a value indicating a conductive state, the occurrence of a power supply failure is indicated in the phase having the current value indicating the non-conductive state. The gist is to determine that there is an abnormality.

  That is, when one of the three phases becomes non-energized due to the occurrence of an energization failure, according to Kirchoff's law, the remaining two phases are in a state where their phases are shifted by 180 ° (electrical angle). Energization continues. On the other hand, the current drop during high-speed rotation due to the influence of the counter electromotive voltage is a phenomenon detected for all phases, and if it is normal, only a specific phase current waveform is small. Absent. Therefore, according to the above configuration, even in a situation where the rotational angular speed condition cannot be determined by detecting the actual rotational angle, it is possible to eliminate the high speed rotation that prevents current from flowing into the motor coil due to the influence of the counter electromotive voltage. The failure of energization can be detected.

  According to a second aspect of the present invention, the drive circuit connects a switching arm formed by connecting in series a pair of switching elements that are turned on / off based on the motor control signal in parallel corresponding to each phase. Each switching element has a parasitic diode, and the current value of each phase is detected by a current sensor provided on the ground side of each switching arm, and the abnormality detection The means supplies the current value of the phase corresponding to the switching element to be turned off even when the motor control signal for turning off any of the ground side switching elements constituting the switching arm is output. When the value indicates a state, the gist is to determine that the phase has an abnormality indicating the occurrence of an energization failure.

  That is, in the configuration in which each phase current sensor is provided on the ground side of each switching arm, when the ground side switching element (lower switching element) is off, the lower switching element is cut off, thereby Current is no longer detected. However, when an open failure occurs in the switching element on the power supply side (upper switching element) arranged on the power supply side, even if the lower switching element is off, the parasitic inductance is not affected by the motor inductance. Current will flow. Therefore, according to the above configuration, it is possible to detect the energization failure with higher accuracy without using the actual rotation angle of the motor.

  The invention according to claim 3 is an addition angle calculation unit that calculates an addition angle corresponding to a motor rotation angle change amount for each calculation cycle based on a deviation between a target torque to be generated by the motor and an actual torque. A control angle calculation unit that calculates a control motor rotation angle by accumulating the addition angle, and the motor control signal output means rotates the motor control signal output means according to the control motor rotation angle. The gist is to output the motor control signal by executing current feedback control in a coordinate system.

  That is, a large torque fluctuation occurs by continuing the same energization as in a normal state in a state where energization failure occurs in any of the three phases. In the resolverless control based on the virtual motor rotation angle based on the deviation between the target torque and the actual torque, the fluctuation of the torque deviation becomes a cause of further torque fluctuation. However, even in such a configuration, by applying the energization failure detection according to claims 1 and 2, it is possible to quickly detect the abnormality and quickly stop the motor drive. As a result, it is possible to avoid a situation in which energization with torque fluctuation as described above is continued.

The gist of the invention described in claim 4 is an electric power steering device including the motor control device according to any one of claims 1 to 3.
According to the above configuration, it is possible to provide an electric power steering device that is excellent in steering feeling by suppressing fluctuations in the motor torque even when energization failure occurs.

  ADVANTAGE OF THE INVENTION According to this invention, the motor control apparatus and electric power steering apparatus which can detect generation | occurrence | production of the electricity supply defect in an electric power supply path | route accurately can be provided, without performing rotational angular velocity detection.

The schematic block diagram of an electric power steering device (EPS). The block diagram which shows the electric constitution of EPS. The circuit diagram of a drive circuit. The schematic block diagram of a 1st control part. The schematic block diagram of a 2nd control part. The flowchart which shows the process sequence of electricity supply failure detection. The wave form diagram which shows transition of each phase electric current value at the time of energization failure generation | occurrence | production. The flowchart which shows the process sequence of electricity supply failure detection. The flowchart which shows the process sequence of electricity supply failure detection.

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, so 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, the motor 12 employs a brushless motor that rotates based on three-phase (U, V, W) driving power. The EPS actuator 10 is configured to apply an assist force based on the motor torque 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, and the ECU 11 controls the steering system based on the steering torque τ detected by the torque sensor 14 and the vehicle speed V detected by the vehicle speed sensor 15. The assist force (target assist force) to be applied to is calculated. Then, in order to generate a motor torque corresponding to the target assist force, by supplying driving power to the motor 12, the operation of the EPS actuator 10 using the motor 12 as a driving source, that is, the assist applied to the steering system. It is configured to control force (power assist control).

Next, the electrical configuration of the EPS of this embodiment will be described.
FIG. 2 is a control block diagram of the EPS of this embodiment. As shown in the figure, the ECU 11 includes a microcomputer 17 that outputs a motor control signal, and a drive circuit 18 that supplies three-phase drive power to the motor 12 based on the motor control signal output from the microcomputer 17. Yes.

  As shown in FIG. 3, the drive circuit 18 of the present embodiment is formed by connecting a plurality of FETs 18a to 18f as switching elements. Specifically, each series circuit of FETs 18a and 18d, FETs 18b and 18e, and FETs 18c and 18f is connected in parallel. In the present embodiment, N-channel MOSFETs are used for these FETs 18a to 18f. And each connection point of the switching element pair connected in series, that is, each connection point 19u, 19v, 19w of FET18a, 18d, FET18b, 18e, FET18c, 18f is respectively via power line 20u, 20v, 20w. The motor 12 is connected to each phase motor coil 12u, 12v, 12w.

  That is, the drive circuit 18 of the present embodiment is formed by connecting three switching arms 18u, 18v, and 18w corresponding to each phase in parallel with a pair of switching elements connected in series as a basic unit (switching arm). It is configured as a known PWM inverter. The motor control signal output from the microcomputer 17 is a gate on / off signal that defines the switching state of each of the FETs 18a to 18f constituting the drive circuit 18.

  That is, when the FETs 18a to 18f are turned on / off in response to the motor control signal, the energization patterns for the phase motor coils 12u, 12v, and 12w are switched. As a result, the DC voltage of the in-vehicle power source (battery) is converted into three-phase (U, V, W) driving power and output to the motor 12.

  Further, the ECU 11 is provided with a current sensor 21 (21u, 21v, 21w) for detecting each phase current value Iu, Iv, Iw of the motor 12. Specifically, these current sensors 21u, 21v, 21w are connected to the low potential side (ground side, lower side in FIG. 2) of the switching arms 18u, 18v, 18w corresponding to the phases of the motor 12, respectively. Each is formed by connecting a shunt resistor. And the microcomputer 17 of this embodiment is based on the output signal (voltage between terminals of shunt resistance) of each of these current sensors 21u, 21v, 21w, the phase current value Iu, which flows through each phase motor coil 12u, 12v, 12w, It is configured to detect Iv and Iw.

  As shown in FIGS. 1 and 2, the ECU 11 of the present embodiment further acquires the rotation angle of the steering wheel 2 detected by the steering sensor (steering angle sensor) 22, that is, the steering angle θs, and the motor resolver 23. Based on the output signal, the rotation angle (electrical angle) θm of the motor 12 is detected. In the present embodiment, the motor resolver 23 receives two-phase sinusoidal signals (a sine signal S_sin and a cosine signal S_cos) whose amplitude changes according to the actual rotation angle (electrical angle) of the motor. A winding type resolver that outputs is adopted. The ECU 11 of the present embodiment outputs a motor control signal based on the phase torque values Iu, Iv, Iw, the rotation angle θm, and the steering angle θs of the motor 12 in addition to the steering torque τ and the vehicle speed V. The microcomputer 17 as a means is configured to execute the output of a motor control signal to the drive circuit 18.

  More specifically, in the microcomputer 17 of the present embodiment, the motor controller 24 includes phase voltage command values Vu *, Vv *, Vw * to be applied to each phase of the motor 12 by executing current control on the orthogonal coordinate axes. A first control unit 25 and a second control unit 26 that calculate (Vu **, Vv **, Vw **), and a PWM conversion unit 27 that converts the phase voltage command value into a motor control signal are provided. Yes. The microcomputer 17 according to the present embodiment is configured to output the motor control signal generated by the motor control unit 24 to the drive circuit 18.

  More specifically, as shown in FIG. 4, the first control unit 25 includes a current command value calculation unit 31 that calculates a current command value corresponding to the target assist force based on the steering torque τ and the vehicle speed V. . In addition, the first control unit 25 includes a d / q conversion unit 32, and the d / q conversion unit 32 detects the phase current values Iu, Iv, and Iw by the motor resolver 23. The d-axis current value Id and the q-axis current value Iq are calculated by mapping onto the orthogonal coordinates of the rotation coordinate system (d / q coordinate system) according to θm, that is, the actual rotation angle of the motor 12. And the 1st control part 25 performs phase feedback command value Vu *, Vv *, Vw * which shows the voltage which should be impressed to each phase of motor 12 by performing current feedback control in the d / q coordinate system. It is configured to calculate.

  That is, the current command value calculation unit 31 calculates the q-axis current command value Iq * as the current command value. Specifically, the current command value calculation unit 31 calculates a q-axis current command value Iq * that generates a larger assist force as the input steering torque τ is larger and the vehicle speed V is smaller. . The d-axis current command value Id * is fixed to “0” (Id * = 0). The d-axis current command value Id * and the q-axis current command value Iq *, together with the d-axis current value Id and the q-axis current value Iq output from the d / q conversion unit 32, the corresponding subtractors 33d and 33q. Is input.

  Next, the current deviations ΔId and ΔIq of the respective axes calculated by the subtracters 33d and 33q are input to the corresponding F / B control units (feedback control units) 34d and 34q, respectively. Each of the F / B control units 34d and 34q executes d / q by executing a feedback control calculation based on the input current deviations ΔId and ΔIq and a predetermined feedback gain (proportional: P, integral: I). A d-axis voltage command value Vd * and a q-axis voltage command value Vq *, which are voltage command values in the coordinate system, are calculated.

  Specifically, each of the F / B control units 34d and 34q sets a proportional component obtained by multiplying the input current deviations ΔId and ΔIq by a proportional gain, and an integral value of the current deviations ΔId and ΔIq, respectively. The integral component obtained by multiplying the integral gain is calculated. Then, the d-axis voltage command value Vd * and the q-axis voltage command value Vq * are generated by adding the proportional component and the integral component.

  Next, the d-axis voltage command value Vd * and the q-axis voltage command value Vq * are mapped onto three-phase (U, V, W) AC coordinates in the d / q inverse conversion unit 35. The first control unit 25 is configured to output the phase voltage command values Vu *, Vv *, Vw * obtained by the reverse conversion executed by the d / q reverse conversion unit 35 to the PWM conversion unit 27. ing.

  On the other hand, as shown in FIG. 5, the second control unit 26 sets the addition angle α corresponding to the motor rotation angle change amount for each calculation cycle based on the deviation between the target torque to be generated by the motor 12 and the actual torque. An addition angle calculation unit 41 for calculating, and a control angle calculation unit 42 for calculating a control angle θc as a virtual motor rotation angle for control by accumulating the addition angle α every calculation cycle. And the 2nd control part 26 performs phase feedback command value Vu **, Vv **, Vw ** by performing electric current feedback control in the rotation coordinate system ((gamma) / (delta) coordinate system) according to the control angle (theta) c. It is configured to calculate.

  More specifically, the addition angle calculation unit 41 of the present embodiment is based on the steering angle θs and the vehicle speed V, a parameter corresponding to the motor torque to be generated by the motor 12, that is, a target corresponding to the target value of the steering torque τ. A target torque calculator 43 for calculating the torque τ * is provided. The target torque τ * calculated by the target torque calculation unit 43 is input to the subtracter 44 together with a parameter corresponding to the actual torque of the motor 12, that is, the steering torque τ detected by the torque sensor 14. Further, based on the torque deviation Δτ calculated by the subtractor 44, the F / B control unit 45 executes a feedback control calculation (proportional integral control: PI control). The addition angle calculation unit 41 is configured to output the control output of the F / B control unit 45 to the control angle calculation unit 42 as the addition angle α.

  On the other hand, the control angle calculation unit 42 holds the previous value of the control angle θc calculated in the previous calculation cycle in a storage area (not shown), and adds a new control by adding the addition angle α to the previous value. The angle θc is calculated. Then, by updating the previous value held in the storage area with the new control angle θc, the control angle θc is calculated by adding the addition angle α every calculation cycle. Yes.

  Next, the control angle θc, which is a virtual motor rotation angle for control calculated in this way, is input to the γ / δ converter 50 together with the phase current values Iu, Iv, and Iw. Then, the γ / δ conversion unit 50 maps the phase current values Iu, Iv, and Iw onto the rotating coordinate system according to the control angle θc, that is, the orthogonal coordinate of the γ / δ coordinate system, thereby obtaining the γ / δ. A γ-axis current value Iγ and a δ-axis current value Iδ are calculated as actual current values in the coordinate system.

  Further, the current command value calculation unit 51 of the second control unit 26 calculates the γ-axis current command value Iγ * and the δ-axis current command value Iδ * as the current command values. The γ-axis current command value Iγ * is input to the subtractor 53a together with the γ-axis current value Iγ, and the δ-axis current command value Iδ * is input to the subtractor 53b together with the δ-axis current value Iδ.

  Next, the current deviations ΔIγ and ΔIδ calculated in the subtracters 53a and 53b are input to the corresponding F / B control units 54a and 54b, respectively. Then, each F / B control unit 54a, 54b executes a feedback control calculation based on the current deviations ΔIγ, ΔIδ and a predetermined feedback gain (proportional: P, integral: I), so that the γ / δ coordinate system A γ-axis voltage command value Vγ * and a δ-axis voltage command value Vδ *, which are voltage command values, are calculated.

  The feedback control calculation performed by each of the F / B controllers 54a and 54b is the same as that of the F / B controllers 34d and 34q on the first controller 25 side. Is omitted.

  Next, the γ-axis voltage command value Vγ * and the δ-axis voltage command value Vδ * are mapped on the three-phase (U, V, W) AC coordinates in the γ / δ inverse conversion unit 55. Then, the second control unit 26 outputs the phase voltage command values Vu **, Vv **, Vw ** obtained by the reverse conversion executed by the γ / δ reverse conversion unit 55 to the PWM conversion unit 27. It has a configuration.

  Here, as shown in FIG. 2, the microcomputer 17 of the present embodiment includes a rotation angle abnormality detection unit 60 that detects the abnormality of the rotation angle θm detected by the motor resolver 23. Specifically, the rotation angle abnormality detection unit 60 of the present embodiment determines whether or not the sum of squares of the sine signal S_sin and the cosine signal S_cos output from the motor resolver 23 is within an appropriate range. Then, based on the determination result, an abnormality in the rotation angle θm is detected as the actual rotation angle of the motor 12. For details of such rotation angle abnormality detection, refer to, for example, the description of JP-A-2006-177750.

  In the present embodiment, the result of the abnormality detection by the rotation angle abnormality detection unit 60 is input to the motor control unit 24 as the rotation angle abnormality detection signal S_rsf. Then, when there is no abnormality in the rotation angle θm, the motor control unit 24 of the present embodiment performs a motor control signal based on the phase voltage command values Vu *, Vv *, Vw * calculated by the first control unit 25. When the rotation angle θm is abnormal, the motor control signal is output based on the phase voltage command values Vu **, Vv **, Vw ** calculated by the second control unit 26. Execute.

  That is, as described above, the second control unit 26 does not use the rotation angle θm detected by the motor resolver 23 that is the actual rotation angle of the motor 12, but the control angle that is a virtual motor rotation angle for control. Using θc, the phase voltage command values Vu **, Vv **, and Vw ** are calculated. For the principle of resolverless control executed by the second control unit 26, see, for example, the description in Patent Document 3 above. In this embodiment, an abnormality is detected in the rotation angle θm by generating a motor control signal based on the phase voltage command values Vu **, Vv **, and Vw ** calculated by the second control unit 26. Even after being performed, the motor control can be continued stably.

(Energization failure detection)
Next, the manner of detecting energization failure in this embodiment will be described.
As shown in FIG. 2, the microcomputer 17 of the present embodiment has an energization failure that detects an energization failure that has occurred in the power supply path that supplies driving power to the motor 12, that is, a state in which no current flows in any of the phases. A detection unit 61 is provided. In addition, as a mode of the energization failure, power lines 20u, 20v, For example, a disconnection failure of 20w or an open failure (open fixing failure) of each of the FETs 18a to 18f constituting the drive circuit 18 can be mentioned. In addition, the motor control unit 24 is inputted with the determination result by the energization failure detection unit 61 as an energization failure detection signal S_pde. Then, the motor control unit 24 of the present embodiment indicates that the motor control unit 24 should stop the motor 12 when the above-described energization failure is detected by the energization failure detection signal S_pde. Is configured to promptly make the fail safe.

  More specifically, the microcomputer 17 of the present embodiment calculates a three-phase current command that calculates phase current command values Iu *, Iv *, and Iw * corresponding to the target current of each phase (U, V, W) on an AC coordinate. A value calculation unit 62 is provided.

  In the present embodiment, the three-phase current command value calculation unit 62 detects the d-axis current command value Id * and q-axis current command value Iq * calculated by the first control unit 25 and the motor resolver 23. The rotation angle θm is input. Further, the rotation angle abnormality detection signal S_rsf output from the rotation angle abnormality detection unit 60 is input to the three-phase current command value calculation unit 62. When there is no abnormality in the rotation angle θm as the actual rotation angle of the input motor 12, the three-phase current command value calculation unit 62 determines the d-axis current command value Id * based on the rotation angle θm. And, by mapping the q-axis current command value Iq * onto the three-phase AC coordinates, the respective phase current command values Iu *, Iv *, and Iw * are calculated.

  Further, the three-phase current command value calculation unit 62 includes a γ-axis current command value Iγ * and a δ-axis current command value Iδ * calculated by the second control unit 26, and a virtual motor rotation angle in its control. A certain control angle θc is input. Then, when the rotation angle θm is abnormal, the three-phase current command value calculation unit 62 determines the γ-axis current command value Iγ * and the δ-axis current command value Iδ * based on the input control angle θc. Are mapped onto three-phase AC coordinates to calculate phase current command values Iu *, Iv *, and Iw *.

  In the current-carrying failure detection unit 61 of the present embodiment, the three-phase current command value calculation unit 62 calculates the phase current values Iu, Iv, Iw detected by the current sensor 21 (21u, 21v, 21w). Each phase current command value Iu *, Iv *, Iw * is input. Then, the energization failure detection unit 61 as an abnormality detection means is provided for each phase based on the mutual relationship between the phase current values Iu, Iv, Iw and the phase current command values Iu *, Iv *, Iw *. In addition, the occurrence of the energization failure is detected.

  Specifically, the energization failure detection unit 61 determines one phase of “U, V, W” as a specific phase and determines whether or not there is an abnormality in the specific phase. And when there is no abnormality in the said phase, it becomes the structure which detects the generation | occurrence | production of the electrical conduction failure sequentially for every phase by changing the specific phase made into the determination object.

  That is, as shown in the flowchart of FIG. 6, the energization failure detection unit 61 first determines whether or not there is an abnormality in the U phase with the U phase as a specific phase (step 101), and when the abnormality is confirmed In (Step 101: YES), it is determined that an energization failure has occurred in the U phase (Step 102). On the other hand, if there is no abnormality in the U phase (step 101: NO), it is then determined whether there is an abnormality in the V phase with the V phase as a specific phase (step 103), and the abnormality is confirmed (step 103) 103: YES), it is determined that an energization failure has occurred in the V phase (step 104). Furthermore, when there is no abnormality in the V phase (step 103: NO), it is then determined whether or not there is an abnormality in the W phase with the W phase as a specific phase (step 105). 105: YES), it is determined that an energization failure has occurred in the W phase (step 106). If it is determined in step 105 that there is no abnormality in the W phase (step 105: NO), it is determined that there is no abnormality in each phase (step 107).

  And the electricity supply failure detection part 61 of this embodiment becomes a structure which detects generation | occurrence | production of the electricity supply failure sequentially for every phase by performing the process of this step 101-step 107 by a predetermined calculation period. ing.

  More specifically, the energization failure detection unit 61 of the present embodiment first performs an abnormality determination (see FIG. 6, steps 101, 103, 105) for the specific phase (X phase: X = U, V, W). Then, it is determined whether or not the phase current value Ix of the specific phase is a value (| Ix | <I1) corresponding to the non-energized state (first condition). Further, the energization failure detecting unit 61 determines whether or not the X phase is a phase (| Ix * |> I2) that should be in the energized state based on the phase current command value Ix * of the specific phase ( Second condition). Then, the energization failure detection unit 61 determines whether the phase current value Iy of the other phase (Y phase, one of the remaining two phases other than the specific phase) is a value (| Iy |> I3) corresponding to the energized state. It is determined whether or not (third condition).

  Here, the thresholds I1, I2, and I3 used for each determination are set to values near “0” in consideration of detection errors. In the present embodiment, the determination of the third condition is that the V phase (X = U, Y = V) when the U phase is the specific phase, and the W phase when the V phase is the specific phase ( X = V, Y = W), and when the W phase is a specific phase, the U phase (X = W, Y = U) is set as the “other phase”. And when all the said 1st-3rd conditions are satisfy | filled, the electricity supply failure detection part 61 of this embodiment determines with there being abnormality which shows generation | occurrence | production of electricity supply failure in the X phase used as the specific phase.

  That is, as shown in FIG. 7, when one of the three phases (the U phase in the example shown in the figure) is in a non-energized state due to the occurrence of an energization failure, Kirchoff's law (Iu + Iv + Iw = 0) The remaining two phases (V and W phases) are continuously energized while their phases are shifted by 180 ° (electrical angle). On the other hand, the decrease in each phase current value Iu, Iv, Iw during high speed rotation due to the influence of the counter electromotive voltage is a phenomenon detected for all phases. Only the waveform is not reduced.

  Focusing on this point, in this embodiment, the phase current value of the specific phase (X = U, V, W, | Ix * |> I2) that should be in the energized state is a value (| Ix | < If it is I1) and the phase current value of the other phase is a value indicating the energization state (| Iy |> I3), it is determined that the specific phase has an abnormality indicating the occurrence of the energization failure. As a result, even in a situation where the actual rotational angle (rotational angle θm) of the motor 12 cannot be detected and the rotational angular velocity condition cannot be determined, it is possible to accurately detect the energization failure.

Next, a processing procedure for detecting energization failure based on the first to third conditions will be described.
As shown in the flowchart of FIG. 8, the energization failure detection unit 61 first determines whether or not all of the first to third conditions are satisfied (step 201 to step 203).

  Specifically, it is determined whether or not the phase current value Ix (absolute value) of the X phase (see FIG. 6, X = U, V, W), which is a specific phase, is smaller than the threshold value I1 (step 201). If it is determined that it is smaller than the threshold value I1 (| Ix | <I1, Step 201: YES), subsequently, whether or not the phase current command value Ix * (absolute value) of the phase exceeds the threshold value I2 Is determined (step 202). Next, when it is determined in this step 202 that the phase current command value Ix * exceeds the threshold value I2 (| Ix * |> I2, step 202: YES), the phase current value Iy of the other phase ( (Absolute value) exceeds a threshold value I3 (step 203). If it is determined in step 203 that the phase current value Iy (absolute value) of the other phase exceeds the threshold value I3 (| Iy |> I3, step 203: YES), that is, the first to third conditions described above are satisfied. If all the conditions are satisfied, it is determined that the X phase, which is the specific phase, has an abnormality indicating the occurrence of an energization failure (step 204).

  In addition, when the energization failure detection unit 61 determines in step 204 that there is an abnormality indicating the occurrence of an energization failure in the X phase, an abnormality flag indicating that the X phase is already in an abnormal state is set next. It is determined whether or not (step 205). If the abnormality flag is not set (step 205: NO), the abnormality flag is set (step 206). If the abnormality flag is already set (step 205: YES), the process of step 206 is not executed.

  Next, the energization failure detection unit 61 increments a continuation time measurement counter (n = n + 1, step 207), and then determines whether or not the counter value n exceeds a predetermined threshold value n0 (step 207). 208). When the counter value n exceeds the threshold value n0 (n> n0, step 208: YES), that is, when the abnormal state indicating the energization failure continues for a predetermined time (n0), the X-phase abnormality is detected. Confirm (step 209).

  In step 208, when the counter value n is equal to or smaller than the threshold value n0 (n ≦ n0, step 208: NO), the energization failure detection unit 61 does not execute the process of step 209.

  On the other hand, if any of the first to third conditions indicated in each of these steps is not satisfied in steps 201 to 203 (step 201: NO, step 202: NO, or step 203: NO), the energization failure detection unit 61 determines that there is no abnormality in the X phase that is the specific phase (step 210). Then, it is determined whether or not the abnormality flag is set (step 211). If the abnormality flag is set (step 211: YES), the abnormality flag is reset (step 212), and the duration measurement is performed. The counter is cleared (n = 0, step 213). In step 211, when the abnormality flag is not set (step 211: NO), the processes in steps 212 and 213 are not executed.

  In other words, the energization failure detection unit 61 according to the present embodiment determines that the specific phase is in an abnormal state indicating the occurrence of energization failure by executing the processing of step 201 to step 213 at every predetermined calculation cycle. In this case, it is further monitored whether or not the abnormal state is continuous. Then, when the abnormal state continues for a predetermined time (n0) set in advance, the abnormality of the specific phase is confirmed, that is, it is determined that an energization failure has occurred. It is the structure which aims at the high precision which becomes.

Further, as shown in FIG. 2, the motor control unit 24 of the present embodiment is configured so that the conduction failure detection unit 61 has a ground side (lower stage) among the FETs 18 a to 18 f constituting the drive circuit 18 (see FIG. 3). The lower stage off signal S_off indicating that the motor control signal for turning off the FETs 18d, 18e, and 18f on the side) is output. Then, the energization failure detection unit 61 outputs the phase current value Ix of the specific phase even though the motor control signal for turning off the ground-side FET (lower FET) corresponding to the specific phase is output. Even in the case of the value (| Ix |> I4) corresponding to the state (fourth condition), it is determined that the specific phase has an abnormality indicating the occurrence of an energization failure.

  That is, as shown in FIG. 3, in the configuration in which the current sensors 21u, 21v, and 21w of the respective phases are provided on the ground side of the corresponding switching arms 18u, 18v, and 18w, the ground that constitutes the drive circuit 18 is provided. When the lower FET (18d, 18e, 18f) on the side is off, the current of the phase is not detected by being blocked by the lower FET. However, when an open failure occurs in the upper stage FET (FETs 18a, 18b, 18c) arranged on the power supply side, even if the lower stage FET is off, the effect of the motor inductance causes the parasitic FET D to pass through. Current will flow. Then, the conduction failure detector 61 of the present embodiment monitors such a phenomenon based on the determination of the fourth condition, thereby causing a conduction failure in each phase, specifically, an upper stage FET constituting the drive circuit 18. It is configured to detect open failures.

Next, a process procedure for detecting energization failure based on the fourth condition will be described.
As shown in the flowchart of FIG. 9, the energization failure detection unit 61 first determines whether or not it is time to turn off the ground-side lower FET corresponding to the specific phase (X phase) (step 301). . If the lower stage FET is off (step 301: YES), it is determined whether the phase current value Ix (absolute value) of the specific phase exceeds the threshold I4 (step 302). If it is determined that the phase current value Ix exceeds the threshold value I4 (step 302: YES), it is determined that there is an abnormality indicating the occurrence of an energization failure in the X phase (step 303).

  Note that the threshold I4 related to the fourth condition in step 302 is set to a value in the vicinity of “0” in consideration of the detection error in the same manner as the thresholds I1, I2, and I3 related to the first to third conditions. . If it is determined in step 301 that it is not the timing at which the lower FET on the ground side is turned off (step 301: NO), the energization failure detection unit 61 does not execute the processing after step 302.

  In addition, when the energization failure detection unit 61 determines in step 303 that there is an abnormality indicating the occurrence of an energization failure in the X phase, an abnormality flag indicating that the X phase is already in an abnormal state is set next. It is determined whether or not (step 304). If the abnormality flag is not set (step 304: NO), the abnormality flag is set (step 305), and the duration measurement counter is incremented (N = N + 1, step 306).

  In this embodiment, the abnormality flag indicating the continuation of the abnormal state based on the fourth condition and the counter for measuring the continuous time relate to the continuation of the abnormal state in the energization failure detection based on the first to third conditions ( It is provided independently of (see FIG. 8). If the abnormality flag has already been set in step 304 (step 304: YES), the energization failure detection unit 61 does not execute the process of step 304, but sets the counter for measuring the continuous time in step 306. Increment.

  Next, the energization failure detection unit 61 determines whether or not the counter value N of the measurement counter exceeds a predetermined threshold value N0 (step 307). When the counter value N exceeds the threshold value N0 (N> N0, step 307: YES), that is, when the abnormal state indicating the energization failure continues for a predetermined time (N0), the X-phase abnormality is detected. Confirm (step 308).

  In step 307, when the counter value N is equal to or less than the threshold value N0 (N ≦ N0, step 307: NO), the energization failure detection unit 61 does not execute the process of step 308.

  On the other hand, if it is determined in step 302 that the fourth condition is not satisfied (step 302: NO), the energization failure detection unit 61 determines that there is no abnormality in the X phase that is the specific phase (step 309). Then, it is determined whether or not the abnormality flag is set (step 310). If the abnormality flag is set (step 310: YES), the abnormality flag is reset (step 311) and the duration time is reached. The measurement counter is cleared (N = 0, step 312). In step 310, when the abnormality flag is not set (step 310: NO), the processing of these steps 311 and 312 is not executed.

  That is, the energization failure detection unit 61 according to the present embodiment performs the processing of the above steps 301 to 312 at every predetermined calculation cycle, so that the specific phase indicates the occurrence of energization failure based on the fourth condition. Even when it is determined that the abnormal state is present, it is further monitored whether the abnormal state is continuous as in the case where the abnormal state is determined based on the first and second conditions. Then, when the abnormal state continues for a predetermined time (N0) set in advance, the abnormality of the specific phase is confirmed, that is, the energization failure is further detected, thereby further detecting the energization failure. The structure is designed to improve accuracy.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) The energization failure detection unit 61 has a value (| Ix | <I1) in which the phase current value of a specific phase (X = U, V, W, | Ix * |> I2) that should be in an energized state indicates a non-energized state ) And the phase current value of the other phase is a value indicating the energized state (| Iy |> I3), it is determined that the specific phase has an abnormality indicating the occurrence of an energization failure.

  That is, when one of the three phases becomes non-energized due to the occurrence of an energization failure, the phases of the remaining two phases are shifted by 180 ° (electrical angle) according to Kirchhoff's law (Iu + Iv + Iw = 0). In such a state, the energization is continued. On the other hand, the decrease in each phase current value Iu, Iv, Iw during high speed rotation due to the influence of the counter electromotive voltage is a phenomenon detected for all phases. Only the waveform is not reduced. Therefore, according to the above configuration, even in a situation where the actual rotational angle (rotational angle θm) of the motor 12 cannot be detected and the rotational angular velocity condition cannot be determined, no current can flow into the motor coil due to the influence of the counter electromotive voltage. Therefore, it is possible to accurately detect the current-carrying failure by eliminating the high-speed rotation.

(2) The drive circuit 18 is formed by connecting three switching arms 18u, 18v, 18w corresponding to each phase in parallel with a pair of switching elements connected in series as a basic unit (switching arm). . Further, N-channel MOSFETs are used for the switching elements (FETs 18 a to 18 f) constituting the drive circuit 18. Further, the phase current values Iu, Iv, Iw are detected by current sensors 21u, 21v, 21w connected in series on the ground side of the switching arms 18u, 18v, 18w constituting the drive circuit 18. Then, the energization failure detection unit 61 outputs the phase current value of the specific phase even though the motor control signal for turning off the ground-side FET (lower FET) corresponding to the specific phase (X phase) is output. Even when Ix is a value corresponding to the energization state (| Ix |> I4), it is determined that there is an abnormality indicating the occurrence of energization failure in the specific phase.

  That is, in the configuration in which the current sensors 21u, 21v, and 21w for each phase are provided on the ground side of the corresponding switching arms 18u, 18v, and 18w, the lower FETs (18d, 18e, 18f) is off, the current of the phase is not detected by being blocked by the lower stage FET. However, when an open failure occurs in the upper stage FET (FETs 18a, 18b, 18c) arranged on the power supply side, even if the lower stage FET is off, the effect of the motor inductance causes the parasitic FET D to pass through. Current will flow. Therefore, according to the above configuration, it is possible to detect the energization failure more accurately without using the actual rotation angle (rotation angle θm) of the motor 12.

  (3) The second control unit 26 calculates the addition angle α corresponding to the motor rotation angle change amount for each calculation cycle based on the deviation between the target torque to be generated by the motor 12 and the actual torque. Further, the second control unit 26 calculates a control angle θc as a virtual motor rotation angle for control by accumulating the addition angle α for each calculation cycle, and a rotating coordinate system (in accordance with the control angle θc) ( The phase voltage command values Vu **, Vv **, and Vw ** are calculated by executing current feedback control in the (γ / δ coordinate system). When an abnormality occurs in the rotation angle θm, which is the actual rotation angle of the motor 12, the motor control unit 24 calculates the phase voltage command values Vu **, Vv **, Vw calculated by the second control unit 26. Based on **, the motor control signal is output.

  That is, a large torque fluctuation occurs by continuing the same energization as in a normal state in a state where energization failure occurs in any of the three phases. In the resolverless control based on the virtual motor rotation angle based on the deviation between the target torque and the actual torque, the fluctuation of the torque deviation becomes a cause of further torque fluctuation. However, even in such a configuration, by applying the energization failure detection described in (1) and (2) above, it is possible to quickly detect the abnormality and quickly stop the motor drive. As a result, it is possible to avoid a situation in which energization with torque fluctuation as described above is continued, and to minimize the deterioration of the steering feeling.

  (4) If it is determined that the specific phase is in an abnormal state in which the specific phase indicates the occurrence of a conductive failure, the current supply failure detection unit 61 further monitors whether the abnormal state is continuous. When the abnormal state continues beyond a predetermined time (n0, N0) set in advance, it is assumed that the abnormality of the specific phase is confirmed, that is, an energization failure has occurred.

According to the above configuration, it is possible to reduce erroneous detection and further increase the accuracy of detection of the energization failure.
In addition, you may change the said embodiment as follows.

  In the above embodiment, the present invention is embodied in the ECU 11 as a motor control device that controls the operation of the motor 12 that is the drive source of the EPS actuator 10. However, the present invention is not limited to this and may be applied to uses other than EPS.

Further, even when applied to EPS, the present invention is not limited to the so-called column type as in each of the above embodiments, and may be applied to, for example, a so-called pinion type or rack assist type EPS.
In the above embodiment, based on the phase current command value Ix * of the specific phase, it is determined whether or not the specific phase is a phase that should be in the energized state (| Ix * |> I2). However, the present invention is not limited to this, and the determination of whether or not the phase should be in the energized state may be based on other state quantities. For example, phase voltage command values Vu *, Vv *, Vw * (Vu **, Vv **, Vw **), Duty as an internal command value that defines the phase voltage command value, or the like may be used. Even with this configuration, it is possible to obtain the same effects as in the above embodiment.

  In the above embodiment, when there is no abnormality in the rotation angle θm, a motor control signal is output based on the phase voltage command values Vu *, Vv *, Vw * calculated by the first control unit 25, and the rotation angle When an abnormality occurs in θm, the motor control signal is output based on the phase voltage command values Vu **, Vv **, and Vw ** calculated by the second control unit 26. . However, the present invention is not limited to this, and the present invention may be applied to one that performs resolverless control without detecting the actual rotation angle of the motor from the beginning.

  The resolverless control mode is not necessarily limited to that based on the virtual motor rotation angle based on the deviation between the target torque and the actual torque as in the above embodiment, and other control methods may be used. You may employ | adopt.

  Furthermore, in addition to the first to third conditions, it may be required that the sum of two phases other than the specific phase is substantially “0”. Thereby, the precision of the energization failure detection can be improved.

  In the above-described embodiment, after determining that the specific phase is in an abnormal state indicating the occurrence of an energization failure, it is further monitored whether or not the abnormal state is continuous. Then, when the abnormal state continues for a predetermined time (n0, N0) set in advance, it is determined that the abnormality of the specific phase is confirmed, that is, an energization failure has occurred. However, the present invention is not limited to this, and it may be configured to detect the occurrence of the energization failure when it is first determined that there is an abnormality.

Next, technical ideas that can be grasped from the above embodiments will be described together with effects.
(A) The motor control device according to claim 3, further comprising: an actual rotation angle detection unit that detects an actual rotation angle of the motor; and a rotation angle abnormality detection unit that detects an abnormality of the detected actual rotation angle, The motor control signal output means executes the current feedback control in a rotating coordinate system according to the actual rotation angle when the actual rotation angle is normal, and when the actual rotation angle is normal, A motor control device, wherein the current feedback control is executed in a rotating coordinate system according to a motor rotation angle on control. Thereby, even when the continuous control is executed in a state where the actual rotation angle cannot be detected, it is possible to accurately detect the energization failure.

  (B) In the motor control device according to any one of claims 1 to 3 and (a) above, the abnormality detection unit is configured to continue when an abnormal state indicating the occurrence of the energization failure continues. A motor control device characterized by determining the abnormality. By adopting such a configuration, it becomes possible to execute the energization failure detection with higher accuracy.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus (EPS), 10 ... EPS actuator, 11 ... ECU, 12 ... Motor, 12u, 12v, 12w ... Motor coil, 17 ... Microcomputer, 18 ... Drive circuit, 18a-18f ... FET, D ... Parasitic Diode, 18u, 18v, 18w ... Switching arm, 20u, 20v, 20w ... Power line, 21 (21u, 21v, 21w) ... Current sensor, 23 ... Motor resolver, 24 ... Motor controller, 25 ... First controller, 26 ... 2nd control part, 27 ... PWM conversion part, 31 ... Current command value calculating part, 32 ... d / q conversion part, 34d, 34q ... F / B control part, 35 ... d / q reverse conversion part, 41 ... Addition angle calculation unit, 42 ... control angle calculation unit, 43 ... target torque calculation unit, 44 ... actual torque calculation unit, 45 ... F / B control unit, 50 ... γ / δ conversion unit, 51 ... current command value Calculation unit, 54a, 54b ... F / B control unit, 55 ... γ / δ inverse conversion unit, 60 ... rotation angle abnormality detection unit, 61 ... conduction failure detection unit, 62 ... three-phase current command value calculation unit, Iu, Iv , Iw, Ix, Iy ... phase current value, θm ... rotation angle, Id ... d-axis current value, Iq ... q-axis current value, Id * ... d-axis current command value, Iq * ... q-axis current command value, ΔId, ΔIq ... current deviation, Vx *, Vu *, Vv *, Vw * ... phase voltage command value, τ ... steering torque, τ * ... target torque, Δτ ... torque deviation, α ... addition angle, θc ... control angle, Iγ ... γ-axis current value, Iδ ... δ-axis current value, Iγ * ... γ-axis current command value, Iδ * ... δ-axis current command value, ΔIγ, ΔIδ ... current deviation, Vu **, Vv **, Vw ** ... phase Voltage command value, Iu *, Iv *, Iw *, Ix * ... Phase current command value, I1, I2, I3, I4 ... Threshold value, n, N ... Counter value, n0, N0 ... Threshold value, S_rsf ... Rotation angle abnormality detection Signal, S_pde ... Energization failure detection signal S_off ... lower off signal.

Claims (4)

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, and power supply to the motor by monitoring the current value of each phase In a motor control device comprising an abnormality detection means for detecting the occurrence of energization failure in the path,
When the current value of the phase that should be in the energized state is a value indicating the non-energized state and the current value of the other phase is a value indicating the energized state, the abnormality detecting means It is determined that there is an abnormality indicating the occurrence of an energization failure in a phase having a value. The motor control device according to claim 1,
The drive circuit is formed by connecting a switching arm formed by connecting in series a pair of switching elements that are turned on / off based on the motor control signal in parallel corresponding to each phase, and each switching element Has a parasitic diode, and the current value of each phase is detected by a current sensor provided on the ground side of each switching arm,
The abnormality detection means outputs a current of a phase corresponding to the switching element that is turned off, even though the motor control signal that turns off any of the ground-side switching elements that constitute the switching arm is output. When the value is a value indicating an energization state, it is determined that the phase has an abnormality indicating the occurrence of an energization failure. In the motor control device according to claim 1 or 2,
An addition angle calculation unit that calculates an addition angle corresponding to a motor rotation angle change amount for each calculation cycle based on a deviation between a target torque to be generated by the motor and an actual torque;
A control angle calculation unit that calculates a motor rotation angle on control by integrating the addition angle,
The motor control signal output means outputs the motor control signal by executing current feedback control in a rotating coordinate system according to the motor rotation angle on the control;
A motor control device.   The electric power steering apparatus provided with the motor control apparatus as described in any one of Claims 1-3.

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