JP2007300727A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller which can detect the rotational angle of a motor accurately, even at a high-speed revolution over the upper limit in control, without having to increase the calculation load of an arithmetic unit. <P>SOLUTION: A microcomputer 20 is equipped with a TA counter, which can sample a pulse signal in cycles, independently of a motor control operation part 22. This TA counter 35 is a well-known hardware AB-phase pulse counter and has a function of increasing/decreasing a counter value in each pulse cycle with respect to the input of the A-phase and B-phase pulse signals, and two of each-phase pulse signals Pu, Pv and Pw, outputted by a rotating angle sensor 26, are inputted into the TA counter 35. Then, the motor rotational angle calculation part 27 provided in the motor control calculation part 22 calculates (detects) the rotating angle θm of the motor, based on the TA counter value V<SB>-</SB>TA outputted from this TA counter 35 and the electrical angle position indicated in a current application position value V<SB>-</SB>pd. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor control device that performs motor control by energizing a rectangular wave.

  Conventionally, in a motor control device that controls the operation of a motor through the supply of three-phase (U, V, W) driving power, a predetermined energization position (electrical angle) set corresponding to every 60 electrical angles of the motor. In some cases, the driving power is supplied by so-called rectangular wave energization that switches the energization phase and energization direction, that is, the energization pattern, at each position “0” to “5”) (see FIGS. 8 and 9).

  In such a rectangular wave drive, although a slight torque ripple occurs when the energized phase is switched, a larger motor torque can be obtained as compared with a so-called sine wave drive in which sine wave energization is performed in each phase. Since there is a feature and high-precision motor rotation angle detection is not required, it is possible to reduce the size of the rotation angle sensor by using a simple hall element or the like. For this reason, for example, in applications that require small size and high output, such as a transmission ratio variable device, the motor control is performed by such rectangular wave energization (see, for example, Patent Document 1).

  By the way, in the case of the motor control apparatus as described above, the three Hall elements constituting the motor rotation angle sensor are arranged so that each output signal has a pulse waveform shown in FIG. That is, each phase pulse signal Pu, Pv, Pw to be output is a predetermined rotation corresponding to the electrical angle magnification (4 times in the examples shown in FIGS. 9 and 10 and the electrical angle in parentheses) set in the motor. The angle (also mechanical angle 90 °) is set as one pulse period (electrical angle 360 °), and the signal level is changed and the phases are shifted by 120 °. Then, the motor control device, for each electrical angle position (position “0” to “5”) indicated by the combination of signal levels of each phase pulse signal Pu, Pv, Pw (pattern “1” to “6”), A motor control signal is output to turn on / off each switching element of the drive circuit so that energization is performed with an energization pattern corresponding to each electrical angle position. Then, it is possible to detect the motor rotation angle by counting the transition of the electrical angle position accompanying the rotation of the motor. For example, in the transmission ratio variable device, the motor rotation angle is detected based on the detected motor rotation angle. Transmission ratio variable control is executed.

Note that the combinations (patterns “1” to “6”) of the signal levels of the phase pulse signals Pu, Pv, and Pw shown in FIG. 10 are “1” when the signal levels are “Hi”. Is expressed as a 3-bit binary number and further converted into a decimal number. In this example, the patterns “5”, “1”, “3”, “2”, “6”, and “4” have positions “0”, “1”, “2”, “3”, “4”, and “5”, respectively. ". That is, for example, a binary notation of a combination in which the P-phase pulse signal Pu (bit2) is “Hi”, the V-phase pulse signal Pv (bit1) is “Lo”, and the W-phase pulse signal Pw (bit0) is “Hi”. [1] [0] [1] is a pattern “5” obtained by converting this into decimal notation. The electrical angle position indicated by the pattern “5” is position “0”.
JP 2005-295688 A

  However, in the variable transmission ratio device, for example, the motor may rotate at an angular velocity exceeding the upper limit of control by external input such as curb collision of steered wheels. In such a case, sampling of each phase pulse signal If the electrical angle position shifts beyond the speed, “skipping” occurs, and the correct rotation angle may not be detected. Therefore, in applications where such a situation is assumed, it is necessary to sample each phase pulse signal at an extremely high speed assuming a high-speed rotation exceeding the upper limit in the control. A high calculation processing capability capable of coping with an increase in calculation load accompanying the high-speed sampling is required. For this reason, a microcomputer having an arithmetic processing capability higher than the capability necessary for actual motor control must be employed, which contributes to an increase in manufacturing cost.

  The present invention has been made to solve the above-described problems, and its object is to achieve an accurate motor rotation angle even at high-speed rotation exceeding the upper limit in control without increasing the calculation load of the calculation device. It is an object of the present invention to provide a motor control device that can detect the above.

  In order to solve the above problems, the invention according to claim 1 is directed to a motor control signal for controlling the rotation of the motor based on a three-phase pulse signal output from a rotation angle sensor provided in the motor. A control signal output means for outputting, and a drive circuit for supplying three-phase drive power to the motor by turning on / off a plurality of switching elements in a predetermined energization pattern in response to the motor control signal, Each phase pulse signal output from the rotation angle sensor has a phase shifted by 120 degrees from each other while the signal level changes with a predetermined rotation angle corresponding to the electrical angle magnification set in the motor as one pulse period. The control signal output means outputs the energization pattern corresponding to each electrical angle position for each electrical angle position indicated by a combination of signal levels of the phase pulse signals. A motor control device that outputs the motor control signal to turn on / off the switching elements at a time by sampling at least two of the phase pulse signals at a period independent of the control signal output means. The gist is provided with a counter that increases or decreases the counter value for each predetermined rotation angle, and motor rotation angle detection means that detects the rotation angle of the motor based on the counter value and the electrical angle position.

  According to the above configuration, by increasing the sampling period of each phase pulse signal in the counter, the pulse period can be counted without “skipping” even at high speed rotation exceeding the upper limit in control. Thus, the correct motor rotation angle can be detected. Since the counter can sample each phase pulse signal in a cycle independent of the motor control signal output means, the calculation load on the control signal output means does not increase by increasing the sampling period. As a result, it is possible to reduce the manufacturing cost by adopting a microcomputer (arithmetic unit) having an appropriate arithmetic processing capability capable of eliminating excessive specifications and meeting the demands on motor control.

The gist of the invention described in claim 2 is that the counter is an AB phase pulse counter that increases or decreases the counter value for each pulse period.
According to the above configuration, the existing motor control device can be realized without requiring a special additional configuration.

  ADVANTAGE OF THE INVENTION According to this invention, the motor control apparatus which can detect an exact motor rotation angle even at the time of the high speed rotation exceeding the upper limit on control, without increasing the calculation load of a calculation apparatus can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a vehicle steering apparatus 1 according to the present embodiment, FIG. 2 is a control block diagram thereof, and FIGS. 3A and 3B are operation explanatory diagrams of transmission ratio variable control. As shown in FIG. 1, the steering shaft 3 to which the steering wheel 2 is fixed is connected to a rack 5 via a rack and pinion mechanism 4. Is converted into a reciprocating linear motion of the rack 5. Then, the steering angle of the steered wheels 6, that is, the steered angle is changed by the reciprocating linear motion of the rack 5, whereby the vehicle traveling direction is changed. The vehicle steering apparatus 1 according to the present embodiment is a so-called rack assist type electric power steering apparatus (EPS), and generates an assist torque generated by a motor 7 as a drive source via a ball screw mechanism (not shown). By transmitting to the rack 5, an assist force is applied to the steering system.

  Further, the vehicle steering apparatus 1 of the present embodiment has a variable transmission ratio that varies the transmission ratio (gear ratio) between the steering angle (steering angle) of the steering 2 and the steering angle (steering angle) of the steered wheels 6. A device 8 and an IFSECU 9 for controlling the operation of the transmission ratio variable device 8 are provided.

  More specifically, the steering shaft 3 includes a first shaft 10 to which the steering 2 is connected and a second shaft 11 to be connected to the rack and pinion mechanism 4, and the transmission ratio variable device 8 includes the first shaft 10 and the first shaft 10. A differential mechanism 12 for connecting the two shafts 11 and a motor 13 for driving the differential mechanism 12 are provided. The transmission ratio variable device 8 adds the rotation driven by the motor to the rotation of the first shaft 10 accompanying the steering operation and transmits it to the second shaft 11, thereby inputting the steering shaft to the rack and pinion mechanism 4. The rotation of 3 is increased (or decelerated).

  That is, as shown in FIGS. 3A and 3B, the transmission ratio variable device 8 uses the steering angle of the steered wheels based on the motor drive (the steered steer angle θts) based on the steering operation (steer steered angle θts). By adding the ACT angle θta), the transmission ratio between the steering angle θs and the turning angle θt is varied.

  In this case, “addition” is defined to include not only addition but also subtraction, and so on. Further, when the “transmission ratio between the steering angle θs and the turning angle θt” is expressed as an overall gear ratio (steering angle θs / steering angle θt), the ACT angle θta in the same direction as the steering turning angle θts is By adding it, the overall gear ratio becomes small (large turning angle θt, see FIG. 3A). Then, the overall gear ratio is increased by adding the ACT angle θta in the opposite direction (small turning angle θt, see FIG. 3B).

  Further, the motor 13 of the present embodiment is a brushless motor, and rotates when three-phase (U, V, W) driving power is supplied from the IFSECU 9. The IFSECU 9 as the motor control device controls the operation of the transmission ratio variable device 8, that is, the ACT angle θta (transmission ratio variable control) by controlling the rotation of the motor 13 through the supply of the driving power.

Next, the electrical configuration and control mode of the vehicle steering apparatus of the present embodiment will be described.
As shown in FIG. 1, the steering angle θs detected by the steering angle sensor 16 and the vehicle speed V detected by the vehicle speed sensor 17 are input to the IFSECU 9. The IFSECU 9 controls the rotation of the motor 13 based on the steering angle θs and the vehicle speed V, thereby executing the operation of the transmission ratio variable device 8, that is, the transmission ratio variable control.

  More specifically, as shown in FIG. 2, the IFSECU 9 includes a microcomputer 20 that outputs a motor control signal and a drive circuit 21 that supplies driving power to the motor 13 based on the motor control signal.

  The microcomputer 20 includes a motor control calculation unit 22 as a control signal output unit. The gear ratio variable control calculation unit 23 and the differential steer control calculation unit 24 included in the motor control calculation unit 22 are respectively provided with a steering angle. θs and vehicle speed V, and vehicle speed V and steering speed ωs are input. The gear ratio variable control calculation unit 23 calculates a gear ratio variable command angle θgr *, which is a control target component for changing the gear ratio (transmission ratio) according to the vehicle speed V, and the differential steer control calculation unit 24 Then, the differential steering command angle θls *, which is a control target component for improving the responsiveness of the vehicle, is calculated according to the steering speed ωs.

  The gear ratio variable command angle θgr * and the differential steer command angle θls * calculated by the gear ratio variable control calculation unit 23 and the differential steer control calculation unit 24 are input to the adder 25. The adder 25 superimposes the gear ratio variable command angle θgr * and the differential steer command angle θls * to thereby obtain the ACT command angle θta * that is the control target amount of the motor 13, that is, the transmission ratio variable device 8. Calculated.

  The motor control calculation unit 22 includes a motor rotation angle calculation unit 27 that calculates (detects) the motor rotation angle θm based on the output signal of the rotation angle sensor 26 provided in the motor 13, and the motor rotation angle θm. And an ACT angle calculator 28 for calculating the ACT angle θta based on the ACT angle θta calculated by the adder 25 together with the ACT command angle θta * calculated by the adder 25. Input to the control calculation unit 29. Then, the position control calculation unit 29 calculates a current command ε by feedback calculation so as to cause the actual ACT angle θta to follow the command value ACT command angle θta *, and outputs it to the motor control signal output unit 30.

  Here, in the present embodiment, the rotation angle sensor 26 provided in the motor 13 includes three Hall elements 26a to 26c corresponding to the respective phases of the motor 13, and the microcomputer 20 outputs the output signal as The phase pulse signals Pu, Pv, and Pw output from the Hall elements 26a to 26c are input according to the rotation of the motor 13 (see FIG. 10).

  The drive circuit 21 employs a known PWM inverter that includes a plurality (2 × 3) of switching elements (FETs) corresponding to the phases of the motor 13. Specifically, the drive circuit 21 includes FETs 31a and 31d, FETs 31b and 31e, and FETs 31c and 31f connected in series to each other in parallel. 32u, 32v, and 32w are connected to each phase motor coil of the motor 13, respectively. The gate terminals of the FETs 31a to 31f are connected to the microcomputer 20, and the FETs 31a to 31f are turned on / off in response to a motor control signal input from the microcomputer 20 (motor control signal output unit 30). The DC power of the in-vehicle power supply 32 is converted into three-phase driving power and supplied to the motor 13.

  In the present embodiment, each phase pulse signal Pu, Pv, Pw output from the rotation angle sensor 26 is input to the motor control signal output unit 30 together with the current command ε calculated by the position control calculation unit 29. Then, the motor control signal output unit 30 as the control signal output means outputs each electrical angle position for each electrical angle position (position) indicated by the combination (pattern) of the signal levels of the phase pulse signals Pu, Pv, and Pw. A motor control signal is output so as to turn on / off the FETs 31a to 31f constituting the drive circuit 21 with an energization pattern corresponding to (see FIGS. 8 to 10). Then, the duty ratio of the motor control signal (on duty ratio of each FET 31a to 31f) is controlled so that the amount of current supplied to the motor 13 corresponds to the value indicated by the current command ε.

(Motor rotation angle detection)
Next, a mode of motor rotation angle detection in the present embodiment will be described.
As shown in FIG. 2, the microcomputer 20 of this embodiment has two systems of pulses input from its input terminals TA_in and TA_out at a cycle independent of the motor control calculation unit 22 (motor control signal output unit 30). A TA counter 35 capable of sampling a signal is provided. This TA counter 35 is a well-known hardware AB phase pulse counter built in the microcomputer 20, and is shown in FIGS. 4 (a) and 4 (b). It has a function to increase / decrease (increment / decrement) the counter value (TA counter value V_TA) for each pulse period with respect to the input of Pa and Pb.

  Specifically, as shown in FIG. 4A, the TA counter 35 is configured such that when the signal level input to the input terminal TA_in (A-phase pulse signal Pa in the example in the figure) is “Hi”. When the signal level (B-phase pulse signal Pb in the example in the figure) input to the input terminal TA_out rises from “Lo” to “Hi”, the TA counter value V_TA is incremented. As shown in FIG. 4B, when the signal level input to the input terminal TA_in is “Hi”, the signal level input to the input terminal TA_out is changed from “Hi” to “Lo”. When it falls, the TA counter value V_TA is decremented.

  In the present embodiment, two of the phase pulse signals Pu, Pv, and Pw output from the rotation angle sensor 26 are input to the TA counter 35. Specifically, the P-phase pulse signal Pu is input to one input terminal TA_in, and the W-phase pulse signal Pw is input to the other input terminal TA_out. Then, the motor rotation angle calculation unit 27 as the motor rotation angle detection means, based on the TA counter value V_TA output from the TA counter 35 and the electrical angle position of the motor 13 (see FIGS. 8 to 10). Calculate (detect) θm.

  More specifically, in the present embodiment, the electrical angle position of the motor 13 is input from the motor control signal output unit 30 to the motor control calculation unit 22 as the energization position value V_pd. Then, as shown in the flowchart of FIG. 6, when the motor rotation angle calculation unit 27 acquires the energization position value V_pd (step 101), it subsequently acquires the TA counter value V_TA from the TA counter 35 (step 102). The motor rotation angle θm is calculated by substituting the energization position value V_pd and the TA counter value V_TA into the following equation (1).

θm = V_TA × (2π / α) + V_pd × (2π / 6α) (1)
α: Electrical angle magnification That is, when the electrical angle magnification α is increased, the motor rotation angle θm cannot be specified only from the electrical angle position (positions “0” to “5”). This is because by increasing the electrical angle magnification α, the “electrical angle 360 °” and the “mechanical angle 360 °” do not match, and the electrical angle (V_pd × (2π / 6)) indicated by the electrical angle position is “ This is because it is not possible to know in which section the mechanical angle 360 ° (2π) is equally divided by the electrical angle magnification α (see FIG. 9, α = 4).

  However, if this is reversed, the motor rotation angle θm can be calculated based on the electrical angle position as long as it is possible to specify “in which section the mechanical angle 360 ° is equally divided by the electrical angle magnification α”. It is also possible.

  Here, as described above, the TA counter 35 of the present embodiment has the “rise” and “rise” of the signal level input to the input terminal TA_out when the signal level input to the input terminal TA_in is “Hi”. The TA counter value V_TA is increased or decreased based on “decrease” (see FIG. 4). Therefore, as long as two pulse signals have the same waveform and are out of phase with each other, it is possible to count not only the A-phase and B-phase pulse signals Pa and Pb but also their pulse periods.

  That is, the phase difference between the P-phase pulse signal Pu and the W-phase pulse signal Pw is 120 °, which is different from the A-phase and B-phase pulse signals Pa and Pb, but is shown in FIGS. As described above, the TA counter 35 can count the pulse period. Then, as shown in FIG. 7, one pulse period, that is, “electric angle 360 °” is “a predetermined rotation angle corresponding to the electric angle magnification α (2π / α, mechanical angle 90 ° in the example in the figure). Therefore, the TA counter value V_TA indicates “any of the sections obtained by equally dividing the mechanical angle 360 ° by the electrical angle magnification α”. Therefore, as shown in the above equation (1), a value obtained by multiplying the TA counter value V_TA by a predetermined rotation angle “2π / α” corresponding to the electrical angle magnification α (V_TA × (2π / α)) is obtained. The motor rotation angle θm can be calculated by adding a value (V_pd × (2π / 6α)) obtained by converting the electrical angle shown in FIG.

  For example, when the TA counter value V_TA is “2”, by multiplying this by a predetermined rotation angle “2π / α” corresponding to the electrical angle magnification α, the motor rotation angle θm becomes “mechanical angle 180 ° to 270 °. "Can be specified in any of the categories. When the electrical angle position indicated by the energization position value V_pd is “3”, the mechanical angle per electrical angle position is “2π / 6α, 15 °”, so the motor rotation angle θm is “ 180 ° + 3 × 15 ° ”can be calculated as 225 °.

  Similarly, when the TA counter value V_TA is “−1”, the motor rotation angle θm is in any of the categories of “mechanical angle 0 ° to −90 °”. When the electrical angle position indicated by the energization position value V_pd is “4”, the motor rotation angle θm can be calculated as “−90 ° + 4 × 15 °” and −30 °.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) According to the above configuration, by increasing the sampling period of each phase pulse signal Pu, Pv, Pw in the TA counter 35, it is possible to avoid “skipping” even at high-speed rotation exceeding the upper limit in control. The pulse period can be counted, and based on this, the correct motor rotation angle θm can be detected. Since the TA counter 35 can sample each phase pulse signal Pu, Pv, Pw at a cycle independent of the motor control calculation unit 22, the calculation of the motor control calculation unit 22 is performed by increasing the sampling cycle. The load does not increase. As a result, it is possible to reduce the manufacturing cost by eliminating the excessive specifications and adopting a microcomputer having an appropriate arithmetic processing capability capable of meeting the requirements for motor control.

  (2) Further, the TA counter 35 is a well-known hardware AB having a function of increasing / decreasing a counter value (TA counter value V_TA) for each pulse period with respect to input of A-phase and B-phase pulse signals. Since a phase pulse counter can be used, it can be realized without requiring any special additional configuration.

In addition, you may change this embodiment as follows.
In the configuration of the present embodiment, a well-known hardware AB phase pulse counter built in the microcomputer 20 is used. However, the present invention is not limited to this, and an AB phase pulse counter provided outside the microcomputer 20 may be used. A counter other than the AB phase pulse counter may be used as long as each phase pulse signal Pu, Pv, Pw is input and has a function capable of increasing or decreasing the count value for each pulse period.

  In the present embodiment, the present invention is embodied in the IFSECU 9 that controls the transmission ratio variable device 8 provided in the vehicle steering apparatus 1. However, the present invention may be embodied in a motor control apparatus used for other purposes.

The schematic block diagram of the steering apparatus for vehicles. The control block diagram of the steering device for vehicles. (A) (b) Action explanatory drawing of transmission ratio variable control. (A) (b) The wave form diagram explaining the pulse period count function of TA counter. (A) (b) The wave form diagram explaining the pulse period count function of TA counter. The flowchart which shows the process sequence of motor rotation angle calculation. The principle explanatory drawing of the motor rotation angle calculation method of this embodiment. The wave form diagram which shows the aspect of a rectangular wave drive. The principle explanatory view of a rectangular wave drive. The principle explanatory drawing of the conventional motor rotation angle calculation method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 2 ... Steering, 6 ... Steering wheel, 8 ... Transmission ratio variable device, 9 ... IFSECU, 13 ... Motor, 20 ... Microcomputer, 21 ... Drive circuit, 26 ... Rotation angle sensor, 26a-26c ... Hall element, 27 ... motor rotation angle calculation unit, 30 ... motor control signal output unit, 35 ... TA counter, 31a to 31f ... FET, θm ... motor rotation angle, Pa ... A phase pulse signal, Pb ... B phase pulse signal, Pu: U-phase pulse signal, Pv: V-phase pulse signal, Pw: W-phase pulse signal, V_pd: Energized position value, V_TA: TA counter value, α: Electrical angle magnification.

Claims (2)

Control signal output means for outputting a motor control signal for controlling the rotation of the motor based on a three-phase pulse signal output from a rotation angle sensor provided in the motor, and a plurality of signals in response to the motor control signal A driving circuit that supplies three-phase driving power to the motor by turning on / off the switching element with a predetermined energization pattern, and each phase pulse signal output from the rotation angle sensor is set in the motor The signal level changes with a predetermined rotation angle corresponding to the electrical angle magnification as one pulse period and has a phase shifted by 120 degrees, and the control signal output means is a combination of the signal levels of the respective phase pulse signals. Before each switching element is turned on / off with the energization pattern corresponding to each electrical angle position. A motor control device that outputs a motor control signal,
A counter that increases or decreases the counter value for each predetermined rotation angle by sampling at least two of the phase pulse signals at a period independent of the control signal output means;
A motor control device comprising: a motor rotation angle detection means for detecting a rotation angle of the motor based on the counter value and the electrical angle position. The motor control device according to claim 1,
The motor control device, wherein the counter is an AB phase pulse counter that increases or decreases a counter value for each pulse period.

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