JP2016013044A - Controller, motor controller and steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller which enables the improvement of immediacy of PWM control.SOLUTION: A motor controller 30 comprises: a first operation part 35 operable to produce first PWM signals αa-αf; a second operation part 36 operable to produce second PWM signals βa-βf; and a synthesized-signal generation part 34 operable to synthesizes the first PWM signals αa-αf and the second PWM signals βa-βf. The first and second operation parts 35 and 36 use carriers which are shifted by T/2 in phase respectively, perform a correction in which a duty instruction value is halved, and produce the first PWM signals αa-αf and the second PWM signals βa-βf based on comparisons between the corrected duty instruction values and the carriers respectively. The synthesized-signal generation part 34 takes a logical OR of the first PWM signals αa-αf and the second PWM signals βa-βf, thereby producing synthesized PWM signals Ca-Cf. The motor controller 30 perform PWM control on a motor 21 by driving by the drive circuit 31 based on the synthesized PWM signals Ca-Cf.

Description

  The present invention relates to a control device, a motor control device, and a steering device that perform PWM (pulse width modulation) control on a controlled object.

  2. Description of the Related Art There is known an electric power steering device that assists a driver's steering operation by applying a motor assist force to a vehicle steering mechanism. This electric power steering apparatus includes a torque sensor that detects a steering torque of a driver, and a motor control apparatus that controls driving of the motor based on the detected steering torque of the torque sensor. The motor control device includes a drive circuit for driving the motor and a microcomputer (hereinafter abbreviated as “microcomputer”) for driving the drive circuit based on the PWM signal. The microcomputer calculates a current command value based on the detected steering torque of the torque sensor, and executes current feedback control according to the deviation so that the current value actually supplied to the motor follows the current command value. A PWM signal is generated. The microcomputer performs PWM control of the motor by driving the drive circuit based on the generated PWM signal. By such PWM control of the motor, an assist force corresponding to the steering torque is applied to the steering mechanism, and the driver's steering operation is assisted.

  By the way, in such a motor control device, if any abnormality occurs in the microcomputer, the microcomputer cannot appropriately calculate the current command value and generate the PWM signal. This is a factor causing abnormalities in the operation of the motor. Therefore, in the motor control device described in Patent Document 1, a sub-microcomputer is provided separately from the main microcomputer that mainly generates the PWM signal. The main microcomputer and the sub microcomputer mutually monitor the state. When the main microcomputer detects an abnormality in the sub-microcomputer, or when the sub-microcomputer detects an abnormality in the main microcomputer, the main microcomputer or the sub-microcomputer performs abnormality handling processing such as stopping the motor drive.

JP 2011-148498 A

  Although the motor control device described in Patent Document 1 has two microcomputers, one sub-microcomputer does not generate a PWM signal. In other words, regarding the PWM control of the motor, the advantage that two microcomputers are mounted cannot be utilized. If the immediacy of the PWM control of the motor can be enhanced by using two microcomputers, a smoother motor operation can be realized, and the steering feeling can be improved.

Such a problem is not limited to the motor control device of the electric power steering apparatus, but is a problem common to a control device that performs PWM control on a control target.
The present invention has been made in view of such circumstances, and an object thereof is to provide a control device, a motor control device, and a steering device that can improve the immediacy of PWM control.

  A control device that solves the above problem includes a plurality of calculation units that generate PWM signals, and a combined signal generation unit that combines the PWM signals generated by the plurality of calculation units, respectively. When N is N and the period of the carrier wave used for generating the PWM signal is T, the plurality of arithmetic units respectively use the carrier wave whose phase is shifted by T / N and multiply the duty instruction value by 1 / N. The PWM signal is generated based on a comparison between the corrected duty instruction value and the carrier wave, and the combined signal generation unit takes a logical sum of the PWM signals generated by the plurality of calculation units. Thus, a composite PWM signal is generated, and the control target is PWM-controlled based on the composite PWM signal.

  When one arithmetic unit generates a PWM signal based on a comparison between the duty instruction value and the carrier wave, assuming that the carrier wave period is T, the PWM signal has one pulse signal during the period T. On the other hand, if the phase of the carrier wave used by each of the N arithmetic units is shifted by T / N as in the above configuration, the pulse signal generation timing by the N arithmetic units can be shifted by T / N. Therefore, N calculation units sequentially generate pulse signals during the period T. Therefore, if a combined PWM signal is generated by taking the logical sum of the PWM signals generated by the respective arithmetic units, a PWM signal including N pulse signals during the period T can be obtained. As a result, the frequency of updating the PWM signal is N times that of the case where the PWM signal is generated by only one arithmetic unit.

  Further, if each calculation unit generates a PWM signal based on a comparison between the corrected duty instruction value multiplied by 1 / N and the carrier wave, the PWM signal calculated by each calculation unit is multiplied by 1 / N. The PWM signal corresponds to the duty instruction value. Therefore, if a PWM signal generated by each calculation unit is combined to generate a combined PWM signal, the combined PWM signal becomes a PWM signal corresponding to the original value of the duty instruction value.

  Therefore, if the drive of the controlled object is controlled based on the composite PWM signal as in the above configuration, the update frequency of the PWM control can be increased while ensuring the driven of the controlled object corresponding to the duty instruction value. The immediacy of PWM control can be improved.

  The control device further includes an abnormality detection unit that detects an abnormality of each of the plurality of calculation units, and when the abnormality detection unit detects an abnormality in any of the plurality of calculation units, the remaining normal calculation units When there are a plurality of normal calculation units, when the number of normal calculation units is M, each of the normal calculation units uses a carrier wave shifted by T / M, and the duty instruction value is set to 1 / M. The PWM signal is generated based on a comparison between the corrected duty instruction value and the carrier wave, and the combined signal generation unit generates a PWM signal generated by each of the plurality of normal calculation units. Preferably, the combined PWM signal is generated by taking a logical sum, and the control target is PWM controlled based on the combined PWM signal.

  According to this configuration, when an abnormality occurs in any of the plurality of calculation units, when there are a plurality of remaining normal calculation units, based on the PWM signal calculated by those normal calculation units. The generation of the composite PWM signal can be continued. Thereby, since the update frequency of a synthetic | combination PWM signal can be ensured, the immediacy of PWM control can be ensured.

  The control device further includes an abnormality detection unit that detects an abnormality of each of the plurality of calculation units, and when the abnormality detection unit detects an abnormality in any of the plurality of calculation units, the remaining normal calculation units Is one, the one normal calculation unit generates a PWM signal based on a comparison between the original value of the duty instruction value and the carrier wave, and the combined signal generation unit is the normal signal Preferably, the PWM signal generated by a single arithmetic unit is output as it is, and the control object is PWM controlled based on the PWM signal generated by the normal single arithmetic unit.

  According to this configuration, when there is only one normal calculation unit, the PWM control can be continued based on the PWM signal generated by the one normal calculation unit. Can be improved.

  On the other hand, in a motor control device comprising: a drive circuit for driving a motor; and a control device that performs PWM control of the motor by driving the drive circuit based on a PWM signal. It is preferable to be used.

According to this configuration, since the immediacy of motor control can be improved, the motor can be operated more smoothly.
Further, a steering system comprising: a motor that applies power to a vehicle steering mechanism; a drive circuit that drives the motor; and a control device that performs PWM control of the motor by driving the drive circuit based on a PWM signal. In the apparatus, the above-described control device is preferably used as the control device.

  According to this configuration, since the immediacy of control for applying power to the steering mechanism by the motor can be improved, the steering feeling can be improved.

  According to the present invention, the immediacy of PWM control can be improved.

The block diagram which shows the schematic structure about one Embodiment of an electric power steering apparatus. The block diagram which shows the structure of the motor control apparatus about the electric power steering apparatus of embodiment. The block diagram which shows the structure of the drive circuit about the motor control apparatus of embodiment. The control block diagram which shows the structure of the 1st calculating part about the motor control apparatus of embodiment. (A)-(g) is a timing chart which shows the relationship between corrected duty instruction | indication value Du ', Dv', Dw 'and 1st PWM signal (alpha) a- (alpha) f. (A), (b) is a timing chart which shows the waveform of the carrier waves (delta) 1, (delta) 2 used by the 1st calculating part and the 2nd calculating part, respectively. The flowchart which shows the procedure of the process performed by the synthetic | combination signal generation part of a motor control apparatus. (A)-(e) shows the relationship between the corrected duty instruction value Du ′, the first PWM signal αa, the second PWM signal βa, and the combined PWM signal Ca, which are used by the first calculation unit and the second calculation unit, respectively. Timing chart. (A)-(g) is the corrected duty instruction value Du ′, the first PWM signal αa, the second PWM signal βa, and the third PWM used by the first to third arithmetic units, respectively, for the modified example of the electric power steering apparatus. 4 is a timing chart showing the relationship between a signal γa and a composite PWM signal Ca. The flowchart which shows the procedure of the process performed by the synthetic | combination signal production | generation part of the motor control apparatus about the modification of an electric power steering apparatus.

Hereinafter, an embodiment of the electric power steering apparatus will be described.
As shown in FIG. 1, the electric power steering apparatus 1 according to the present embodiment provides an assisting force to the steering mechanism 10 by a steering mechanism 10 that steers the steered wheels 16 based on a driver's operation of the steering wheel 11 and a motor 21. An assist mechanism 20 to be applied and a motor control device 30 for controlling driving of the motor 21 are provided.

  The steering mechanism 10 includes a steering shaft 12 that serves as a rotating shaft of the steering wheel 11, and a rack shaft 14 that is coupled to a lower end portion of the steering shaft 12 via a rack and pinion mechanism 13. In the steering mechanism 10, when the steering shaft 12 rotates in response to the driver's operation of the steering wheel 11, the rotational motion is converted into the axial reciprocating linear motion of the rack shaft 14 via the rack and pinion mechanism 13. The reciprocating linear motion of the rack shaft 14 in the axial direction is transmitted to the steered wheels 16 via the tie rods 15 connected to both ends thereof, whereby the steered angle of the steered wheels 16 is changed and the traveling direction of the vehicle is changed. The

  The assist mechanism 20 includes a motor 21 and a speed reducer 22 that connects the output shaft 21 a of the motor 21 and the steering shaft 12. The motor 21 is a brushless motor. The assist mechanism 20 applies assist force (assist torque) to the steering shaft 12 by decelerating the rotation of the output shaft 21a of the motor 21 by the speed reducer 22 and transmitting it to the steering shaft 12.

  The electric power steering apparatus 1 is provided with various sensors for detecting the state quantity of the vehicle and the operation amount of the driver. For example, the steering shaft 12 is provided with a torque sensor 40 that detects a steering torque Th applied to the steering shaft 12 when a driver performs a steering operation. The motor 21 is provided with a rotation angle sensor 41 for detecting the rotation angle θ of the output shaft 21a. The vehicle is provided with a vehicle speed sensor 42 for detecting the traveling speed Spd. Outputs of these sensors 40 to 42 are taken into the motor control device 30. The motor control device 30 performs assist control for applying assist force to the steering shaft 12 by PWM control of the motor 21 based on the steering torque Th, the motor rotation angle θ, the vehicle speed Spd, and the like detected by the sensors 40 to 42. Run.

  As shown in FIG. 2, the motor control device 30 includes a drive circuit 31, current sensors 32u, 32v, and 32w, a pre-driver 33, a combined signal generation unit 34, and a first and a second that are configured around a microcomputer. Second calculation units 35 and 36 and a calculation timing adjustment unit 37 are provided.

  As shown in FIG. 3, the drive circuit 31 is formed by connecting a series circuit of an upper FET 31a and a lower FET 31d, a series circuit of an upper FET 31b and a lower FET 31e, and a series circuit of an upper FET 31c and a lower FET 31f in parallel. It has a known inverter circuit. Each upper FET 31a to 31c is electrically connected to a power supply (power supply voltage “+ Vcc”). The lower FETs 31d to 31f are grounded. A connection point P1 between the upper FET 31a and the lower FET 31d, a connection point P2 between the upper FET 31b and the lower FET 31e, and a connection point P3 between the upper FET 31c and the lower FET 31f are connected to the motor 21 via the feed lines Wu, Wv, and Ww. Each phase coil is connected. The FETs 31a to 31f are switched based on drive signals Ga to Gf output from the pre-driver 33. Based on the switching of the FETs 31a to 31f, the DC power supplied from the power source is converted into three-phase AC power. The converted three-phase AC power is supplied to each phase coil of the motor 21 via the feed lines Wu, Wv, Ww, thereby driving the motor 21.

  The current sensors 32u, 32v, and 32w each have a known configuration having shunt resistors connected in series to the lower FETs 31d to 31f. The current sensors 32u, 32v, and 32w detect the phase current values Iu, Iv, and Iw supplied to the motor 21, respectively.

  As shown in FIG. 2, the first calculation unit 35 takes in outputs of the torque sensor 40, the vehicle speed sensor 42, the rotation angle sensor 41, and the current sensors 32 u, 32 v, and 32 w. The first calculation unit 35 generates first PWM signals αa to αf based on the steering torque Th, the vehicle speed Spd, the motor rotation angle θ, and the phase current values Iu, Iv, and Iw detected by these sensors.

  Specifically, as shown in FIG. 4, the first calculation unit 35 includes a current command value calculation unit 50, first and second subtractors 51a and 51b, and first and second feedback (F / B) control units. 52a, 52b, a two-phase / three-phase converter 53, a duty instruction value calculator 54, a duty instruction value corrector 55, a PWM signal generator 56, and a three-phase / two-phase converter 57. ing.

  The current command value calculation unit 50 calculates a d-axis current command value Id * and a q-axis current command value Iq *. The d-axis current command value Id * and the q-axis current command value Iq * indicate target values for the supply current of the motor 21 in the d / q coordinate system. The current command value calculation unit 50 calculates a q-axis current command value Iq * based on the steering torque Th and the vehicle speed Spd. For example, the current command value calculation unit 50 sets the absolute value of the q-axis current command value Iq * to a larger value as the absolute value of the steering torque Th increases and as the vehicle speed Spd decreases. Further, the current command value calculation unit 50 sets the d-axis current command value Id * to zero. The current command value calculation unit 50 outputs the calculated d-axis current command value Id * and q-axis current command value Iq * to the first and second subtracters 51a and 51b, respectively.

  The three-phase / two-phase converter 57 takes in the respective phase current values Iu, Iv, Iw and the motor rotation angle θ. The three-phase / two-phase converter 57 calculates the d-axis current value Id and the q-axis current value Iq by mapping each phase current value Iu, Iv, Iw to the d / q coordinate system using the motor rotation angle θ. . The d-axis current value Id and the q-axis current value Iq indicate actual supply current values of the motor 21 in the d / q coordinate system. The three-phase / two-phase converter 57 outputs the calculated d-axis current value Id and q-axis current value Iq to the first and second subtracters 51a and 51b, respectively.

  The first subtractor 51a obtains a d-axis current deviation ΔId by subtracting the d-axis current value Id from the d-axis current command value Id *, and outputs the d-axis current deviation ΔId to the first F / B control unit 52a. . The first F / B control unit 52a generates the d-axis voltage command value Vd * by executing current feedback control based on the d-axis current deviation ΔId so that the d-axis current value Id follows the d-axis current command value Id *. The d-axis voltage command value Vd * is then output to the two-phase / three-phase converter 53.

  The second subtractor 51b obtains a q-axis current deviation ΔIq by subtracting the q-axis current value Iq from the q-axis current command value Iq *, and outputs the q-axis current deviation ΔIq to the second F / B control unit 52b. . The second F / B control unit 52b generates the q-axis voltage command value Vq * by executing current feedback control based on the q-axis current deviation ΔIq so that the q-axis current value Iq follows the q-axis current command value Iq *. The q-axis voltage command value Vq * is then output to the two-phase / three-phase converter 53.

  The two-phase / three-phase converter 53 captures the motor rotation angle θ. The two-phase / three-phase conversion unit 53 uses the motor rotation angle θ to map the d-axis voltage command value Vd * and the q-axis voltage command value Vq * to the three-phase coordinate system, whereby each phase voltage in the three-phase coordinate system. The command values Vu *, Vv *, Vw * are calculated, and these phase voltage command values Vu *, Vv *, Vw * are output to the duty instruction value calculation unit 54.

  The duty instruction value calculation unit 54 calculates the duty instruction values Du, Dv, Dw of each phase corresponding to the phase voltage instruction values Vu *, Vv *, Vw *. The duty instruction values Du, Dv, and Dw indicate the on-duty ratios of the upper FETs 31a to 31c of the drive circuit 31 in the range of “0% to 100%”, respectively. The duty instruction value calculation unit 54 outputs the calculated duty instruction values Du, Dv, Dw to the duty instruction value correction unit 55.

  The duty instruction value correction unit 55 corrects the duty instruction values Du, Dv, and Dw based on the following equations (1) to (3). “N” indicates the number of arithmetic units that generate PWM signals. That is, in this embodiment, the value of N is set to “2”.

Du ′ = Du / N (1)
Dv ′ = Dv / N (2)
Dw ′ = Dw / N (3)
Therefore, in the present embodiment, the corrected duty instruction values Du ′, Dv ′, and Dw ′ are set in the range of “0% to 50%”, respectively. The duty instruction value correction unit 55 outputs the corrected duty instruction values Du ′, Dv ′, Dw ′ calculated based on the equations (1) to (3) to the PWM signal generation unit 56.

  For example, as shown in FIGS. 5A to 5G, the PWM signal generation unit 56 is a carrier wave (PWM carrier) δ1 composed of corrected duty instruction values Du ′, Dv ′, Dw ′ and a triangular wave with a period T. Based on the comparison, the first PWM signals αa to αf are generated. Specifically, as shown in FIGS. 5B, 5D, and 5F, the PWM signal generator 56 is turned on when the duty instruction values Du, Dv, and Dw are larger than the value of the carrier wave δ1. When the duty instruction values Du, Dv, and Dw are smaller than the value of the carrier wave δ1, the first PWM signals αa to αc indicating the off signals are generated. Further, as shown in FIGS. 5C, 5E, and 5G, the PWM signal generation unit 56 turns on signals when the duty instruction values Du, Dv, and Dw are smaller than the value of the carrier wave δ1. When the duty instruction values Du, Dv, and Dw are larger than the value of the carrier wave δ1, first PWM signals αd to αf indicating an off signal are generated. The first PWM signals αa to αf are signals for turning on / off the FETs 31a to 31f of the drive circuit 31, respectively. For example, when the first PWM signal αa is an on signal, the upper FET 31a is turned on, and when the first PWM signal αa is an off signal, the upper FET 31a is turned off. As shown in FIG. 2, the PWM signal generation unit 56 outputs the generated first PWM signals αa to αf to the combined signal generation unit 34.

  The first calculation unit 35 has a self-diagnosis function for monitoring its own state, and transmits the result Sd1 of the self-diagnosis to the composite signal generation unit 34 by, for example, a watchdog signal. Therefore, the composite signal generation unit 34 can detect whether or not the first calculation unit 35 is normal based on the self-diagnosis result Sd1 transmitted from the first calculation unit 35.

  The second calculation unit 36 has the same performance as the first calculation unit 35. That is, the second calculation unit 36 uses the same calculation method as the first calculation unit 35 to calculate the second PWM signal βa˜ based on the steering torque Th, the vehicle speed Spd, the motor rotation angle θ, and the phase current values Iu, Iv, Iw. βf is generated. Further, the second calculation unit 36 also has a self-diagnosis function for monitoring its own state, and transmits the result Sd2 of the self-diagnosis to the combined signal generation unit 34. Therefore, the composite signal generation unit 34 can detect whether or not the second calculation unit 36 is normal based on the self-diagnosis result Sd2 transmitted from the second calculation unit 36.

  The calculation timing adjustment unit 37 adjusts the calculation timings of the first calculation unit 35 and the second calculation unit 36. Specifically, when the number of arithmetic units that generate the PWM signal is N and the period of the carrier wave δ1 used for generating the PWM signal is “T”, the arithmetic timing adjustment unit 37 calculates the arithmetic timing of the second arithmetic unit 36. Is delayed by “T / N” from the calculation timing of the first calculation unit 35. That is, in the present embodiment, the calculation timing adjustment unit 37 delays the calculation timing of the second calculation unit 36 by “T / 2” from the calculation timing of the first calculation unit 35. Specifically, as shown in FIGS. 6A and 6B, when the calculation timing adjustment unit 37 starts the process of synchronizing the calculation units 35 and 36 at time t1, first, at the time t1, the calculation is performed at the first time. A clock trigger signal is transmitted to the arithmetic unit 35. Thereafter, the calculation timing adjustment unit 37 transmits a clock trigger signal to the second calculation unit 36 at time t2 when time T / 2 has elapsed from time t1. As a result, a phase difference of “T / 2” is generated between the carrier wave δ1 of the first calculation unit 35 and the carrier wave δ2 of the second calculation unit 36. As a result, the calculation timing of the second PWM signals βa to βf of the second calculation unit 36 can be delayed by “T / 2” from the calculation timing of the first PWM signals αa to αf of the first calculation unit 35.

  As shown in FIG. 2, the composite signal generation unit 34 monitors the states of the calculation units 35 and 36 based on the self-diagnosis results Sd1 and Sd2 transmitted from the first calculation unit 35 and the second calculation unit 36, respectively. . The combined signal generator 34 is calculated by the first PWM signals αa to αf calculated by the first calculator 35 and the second calculator 36 when both the first calculator 35 and the second calculator 36 are normal. The synthesized PWM signals Ca to Cf are generated by synthesizing the second PWM signals βa to βf. Specifically, when “y = a, b, c, d, e, f”, the combined signal generation unit 34 obtains a logical sum of the first PWM signal αy and the second PWM signal βy to generate a combined PWM signal. Cy is generated. Therefore, the combined PWM signal Cy indicates an on signal when either the first PWM signal αy or the second PWM signal βy is an on signal, and when both the first PWM signal αy and the second PWM signal βy are off signals, Indicates an off signal.

  Further, the combined signal generation unit 34 repeatedly executes the process shown in FIG. 7 at a predetermined calculation cycle based on the states of the first calculation unit 35 and the second calculation unit 36. That is, the composite signal generation unit 34 first determines whether or not an abnormality has been detected in one of the first calculation unit 35 and the second calculation unit 36 (S1). Then, when both the first calculation unit 35 and the second calculation unit 36 are normal (S1: NO), the combined signal generation unit 34 ends this process. On the other hand, when the combined signal generation unit 34 detects an abnormality in one of the first calculation unit 35 and the second calculation unit 36 (S1: NO), the combined signal generation unit 34 sends the abnormality detection signal Se to the normal calculation unit. Transmit (S2). For example, when the composite signal generation unit 34 detects an abnormality in the second calculation unit 36, the composite signal generation unit 34 transmits an abnormality detection signal Se to the first calculation unit 35. At this time, as shown in FIG. 4, when the duty instruction value correction unit 55 of the first calculation unit 35 receives the abnormality detection signal Se, the duty instruction value Du, Dv, and Dw correction processing is stopped. That is, the duty instruction value correction unit 55 outputs the original values Du, Dv, and Dw of the duty instruction value calculated by the duty instruction value calculation unit 54 to the PWM signal generation unit 56 as they are. Therefore, the first calculator 35 outputs the first PWM signals αa to αf corresponding to the duty instruction values Du, Dv, and Dw set in the range of “0% to 100%”.

  Then, as shown in FIG. 7, following the process of S2, the composite signal generation unit 34 transitions to a synthesis stop mode in which the PWM signal output from the normal calculation unit is output as it is (S3). That is, when the composite signal generation unit 34 detects an abnormality in the second calculation unit 36, the first PWM signal αa to αf output from the first calculation unit 35 is output as it is. In addition, when the composite signal generation unit 34 detects an abnormality in the first calculation unit 35, it outputs the second PWM signals βa to βf output from the second calculation unit 36 as they are.

  As illustrated in FIG. 3, the pre-driver 33 amplifies any one of the combined PWM signals Ca to Cf, the first PWM signals αa to αf, and the second PWM signals βa to βf output from the combined signal generation unit 34. Drive signals Ga to Gf are generated. The pre-driver 33 applies the drive signals Ga to Gf to the gate terminals of the FETs 31a to 31f of the drive circuit 31, thereby driving the FETs 31a to 31f to open and close. The motor 21 is driven based on the opening / closing drive of the FETs 31a to 31f, and assist control for applying an assist force to the steering shaft 12 is executed.

Next, operation | movement of the electric power steering apparatus 1 of this embodiment is demonstrated.
When both the first calculation unit 35 and the second calculation unit 36 are normal, the first calculation unit 35 and the second calculation unit 36 have the first PWM signal αa and the second PWM signal as shown in FIGS. βa is generated respectively. That is, as shown in FIGS. 8A and 8C, the first calculator 35 compares the corrected duty instruction value Du ′ (= Du / 2) with the carrier wave δ1 to compare the first PWM signal αa. Is generated. Therefore, the first PWM signal αa is a PWM signal corresponding to the duty instruction value Du / 2. Further, as shown in FIGS. 8B and 8D, the second calculation unit 36 also compares the corrected duty instruction value Du ′ (= Du / 2) with the carrier wave δ2 to compare the second PWM signal βa. Is generated. Accordingly, the second PWM signal βa is also a PWM signal corresponding to the duty instruction value Du / 2, similarly to the first PWM signal αa. However, the second PWM signal βa is a signal having a phase difference of “T / 2” with respect to the first PWM signal αa.

  Then, as shown in FIG. 8 (e), the combined signal generation unit 34 combines the first PWM signal αa and the second PWM signal βa shown in FIGS. 8 (c) and 8 (d), respectively. A PWM signal Ca is generated. Thus, the combined PWM signal Ca is a signal obtained by combining the first PWM signal αa corresponding to the duty instruction value Du / 2 and the second PWM signal βa corresponding to the duty instruction value Du / 2. Note that the combined signal generation unit 34 generates other combined PWM signals Cb to Cf in the same manner. The motor control device 30 controls the drive of the motor 21 by switching the FETs 31a to 31f of the drive circuit 31 based on the combined PWM signals Ca to Cf.

  For example, when an abnormality occurs in the second calculation unit 36, the first calculation unit 35 compares the original values Du, Dv, and Dw of the duty instruction values with the carrier wave δ1 to obtain the first PWM signals αa to αf. Generate. Therefore, the first PWM signal αa is a PWM signal corresponding to the duty instruction values Du, Dv, Dw. At this time, the composite signal generation unit 34 outputs the first PWM signals αa to αf as they are. Therefore, the motor control device 30 controls the driving of the motor 21 by switching the FETs 31a to 31f of the drive circuit 31 based on the first PWM signals αa to αf. The motor control device 30 controls driving of the motor 21 based on the second PWM signals βa to βf generated by the second calculation unit 36 when an abnormality occurs in the first calculation unit 35.

According to the electric power steering device 1 and the motor control device 30 of the present embodiment described above, the following operations and effects (1) and (2) can be obtained.
(1) As shown in FIG. 8 (e), the combined PWM signal Ca is a PWM signal corresponding to the duty instruction value Du and a signal having two pulse signals during the period T of the carrier waves δ1 and δ2. It becomes. That is, the combined PWM signal Ca of the present embodiment is a PWM signal having twice the update frequency as compared with a PWM signal generated by using a carrier wave having a period T by one arithmetic unit. The same applies to the combined PWM signals Cb to Cf. Since the motor control device 30 drives the drive circuit 31 on the basis of these combined PWM signals Ca to Cf, the update frequency of the PWM control of the motor 21 can be increased, so that the immediacy of the PWM control can be improved. it can. As a result, since the immediacy of the assist control can be improved, the motor 21 can be operated more smoothly and the steering feeling is improved.

  (2) When an abnormality occurs in one of the first calculation unit 35 and the second calculation unit 36, the PWM control of the motor 21 can be continued based on the PWM signal generated by the normal calculation unit. . Thereby, the continuity of the drive control of the motor 21 can be improved, and as a result, the continuity of the assist control can be improved.

In addition, the said embodiment can also be implemented with the following forms.
The method of shifting the phases of the carriers δ1 and δ2 used by the first calculation unit 35 and the second calculation unit 36 by “T / 2” is not limited to the method using the calculation timing adjustment unit 37, and an appropriate method is adopted. can do. For example, the phases of the carriers δ1 and δ2 may be shifted by “T / 2” by the first calculator 35 and the second calculator 36 adjusting the phases of the carriers δ1 and δ2 through mutual communication.

The second computing unit 36 is not limited to having the same performance as the first computing unit 35, and may have only a part of the function of the first computing unit 35.
The carrier waves δ1 and δ2 are not limited to triangular waves but may be sawtooth waves or the like.

  In the above embodiment, each abnormality of the first calculation unit 35 and the second calculation unit 36 is detected by the composite signal generation unit 34. However, the abnormality detection means for detecting these abnormalities is not limited to this, and an appropriate configuration. Can be adopted. For example, the first computing unit 35 and the second computing unit 36 may detect the abnormality of each computing unit 35, 36 by monitoring the state of each other. Combining this configuration with the configuration in which the combined signal generation unit 34 monitors the states of the calculation units 35 and 36 can improve the abnormality detection accuracy of the calculation units 35 and 36. Further, instead of the configuration in which the combined signal generation unit 34 monitors the states of the calculation units 35 and 36, only the configuration in which the first calculation unit 35 and the second calculation unit 36 monitor the states of each other may be used. According to this configuration, it is possible to reduce the calculation burden on the composite signal generation unit 34.

  The motor control device 30 may have three or more calculation units. For example, when the number of arithmetic units is three, as shown in FIGS. 9A to 9C, the three arithmetic units respectively use carriers δ1, δ2, and δ3 whose phases are shifted by T / 3. . Further, the three arithmetic units respectively perform correction for multiplying the duty instruction value Du by 1/3, for example, and, as shown in FIGS. 9D to 9F, the corrected duty instruction value Du / 3 and the carrier wave δ1. , Δ2, and δ3, the first PWM signal αa, the second PWM signal βa, and the third PWM signal γa are respectively generated. Then, as shown in FIG. 9G, the composite signal generation unit 34 generates a composite PWM signal Ca by taking the logical sum of these PWM signals αa, βa, and γa. In short, if the number of operation units is N and the period of the carrier wave used for generating the PWM signal is T, the plurality of operation units respectively use carriers whose phases are shifted by T / N. In addition, the plurality of calculation units perform correction by multiplying the duty instruction values Du, Dv, and Dw by 1 / N, and based on comparison of the corrected duty instruction values Du / N, Dv / N, and Dw / N with the carrier wave Each PWM signal is generated. Then, the combined signal generation unit 34 generates combined PWM signals Ca to Cf by taking a logical sum of the PWM signals calculated by the respective calculation units.

  When the motor control device 30 has three or more arithmetic units, it is effective to repeatedly execute the processing shown in FIG. 10 at a predetermined cycle by the composite signal generation unit 34. That is, the composite signal generation unit 34 first determines whether any abnormality is detected from among the plurality of calculation units (S10). Then, when all the calculation units are normal (S10: NO), the combined signal generation unit 34 ends this process. On the other hand, when detecting an abnormality in any of the plurality of calculation units (S10: YES), the combined signal generation unit 34 determines whether there are a plurality of normal calculation units (S11). ). Then, when there are a plurality of normal calculation units (S11: YES), the composite signal generation unit 34 uses the remaining normal calculation units and calculation to detect the abnormality detection signal Se including information on the number M of normal calculation units. Each is transmitted to the timing adjustment unit 37 (S12). At this time, the calculation timing adjustment unit 37 uses the carrier wave shifted by T / M based on the information on the number M included in the abnormality detection signal Se so that the remaining normal calculation units use carrier waves shifted by T / M. Adjust the phase shift. Further, the duty instruction value correction unit 55 of the normal calculation unit is based on the information on the number M of normal calculation units included in the abnormality detection signal Se, and the corrected duty based on the following equations (4) to (6). The instruction values Du ′, Dv ′, Dw ′ are calculated.

Du ′ = Du / M (4)
Dv ′ = Dv / M (5)
Dw ′ = Dw / M (6)
Then, after the process of S11, the composite signal generation unit 34 transitions to a composite maintenance mode in which the composite PWM signals Ca to Cf are generated by taking the logical sum of the PWM signals output from the plurality of normal arithmetic units, respectively. (S13).

On the other hand, when there is only one normal calculation unit (S11: NO), the composite signal generation unit 34 performs the same processing as S2 and S3 illustrated in FIG.
According to such a configuration, when an abnormality occurs in any of the plurality of calculation units, if there are a plurality of remaining normal calculation units, the PWM signal calculated by those normal calculation units The generation of the composite PWM signal can be continued based on the above. Thereby, since the update frequency of a synthetic | combination PWM signal can be ensured, the immediacy of the PWM control of the motor 21 can be ensured. As a result, the immediacy of assist control can be ensured.

As the motor 21, a brush motor may be used instead of the brushless motor.
-The motor control apparatus 30 of the said embodiment can also be used for the electric power steering apparatus which provides the assist force to the rack shaft 14 with a motor, for example. In addition to an electric power steering device, for example, a steer-by-wire steering device, a motor that applies power to the steering mechanism, a drive circuit for driving the motor, and a drive circuit that is driven based on the PWM signal The present invention can be used in various steering devices including a control device that performs PWM control of a motor. Furthermore, the configuration of the motor control device 30 of the above embodiment is not limited to the motor control device of the steering device, and can be applied to an appropriate motor control device.

  The configuration of the above embodiment is not limited to the motor control device, and can be applied to an appropriate control device that performs PWM control of a control target, such as an LED dimming device.

  T ... period, αa to αf ... first PWM signal, βa to βf ... second PWM signal, γa ... third PWM signal, δ1 to δ3 ... carrier wave, Ca to Cf ... combined PWM signal, Du, Dv, Dw ... duty indication value, DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus, 10 ... Steering mechanism, 21 ... Motor, 30 ... Motor control apparatus, 31 ... Drive circuit, 34 ... Synthetic signal production | generation part (abnormality detection means), 35 ... 1st calculating part, 36 ... 2nd Arithmetic unit.

Claims (5)

A plurality of arithmetic units for generating PWM signals;
A combined signal generation unit that combines the PWM signals generated by the plurality of arithmetic units,
When the number of the arithmetic units is N and the period of the carrier wave used for generating the PWM signal is T,
The plurality of arithmetic units respectively use a carrier wave whose phase is shifted by T / N and perform a correction for multiplying a duty instruction value by 1 / N, and based on a comparison between the corrected duty instruction value and the carrier wave, the PWM Each generates a signal,
The combined signal generation unit generates a combined PWM signal by taking a logical sum of the PWM signals respectively generated by the plurality of calculation units,
A control device that performs PWM control of a control target based on the combined PWM signal. Further comprising an abnormality detection means for detecting an abnormality in each of the plurality of arithmetic units,
When an abnormality is detected in any of the plurality of calculation units by the abnormality detection unit, when there are a plurality of remaining normal calculation units,
When the number of normal computing units is M, each of the normal computing units uses a carrier wave that is shifted by T / M, and performs a correction that multiplies the duty instruction value by 1 / M. Each of the PWM signals based on a comparison between the duty instruction value and the carrier wave,
The combined signal generation unit generates the combined PWM signal by taking a logical sum of the PWM signals respectively generated by the normal arithmetic units.
The control device according to claim 1, wherein the control object is PWM-controlled based on the combined PWM signal. Further comprising an abnormality detection means for detecting an abnormality in each of the plurality of arithmetic units,
When an abnormality is detected in any of the plurality of calculation units by the abnormality detection unit, when there is only one remaining normal calculation unit,
The normal one calculation unit generates a PWM signal based on a comparison between the original value of the duty instruction value and the carrier wave,
The combined signal generation unit outputs the PWM signal generated by the normal one calculation unit as it is,
The control device according to claim 1, wherein the control target is PWM-controlled based on a PWM signal generated by the normal one arithmetic unit. A drive circuit for driving the motor;
A control device for PWM controlling the motor by driving the drive circuit based on a PWM signal;
The motor control apparatus with which the control apparatus as described in any one of Claims 1-3 is used as said control apparatus. A motor for applying power to a vehicle steering mechanism;
A drive circuit for driving the motor;
A control device for PWM controlling the motor by driving the drive circuit based on a PWM signal;
A steering device in which the control device according to any one of claims 1 to 3 is used as the control device.