JP2010148324A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller preventing deterioration in efficiency of a three-phase motor and output accuracy thereof, caused by an error in attaching a rotation angle detecting section. <P>SOLUTION: The motor controller 100 is provided with: a rotation angle detecting section 11 for detecting the rotation angle of a rotor as an initial rotation angle when the three-phase motor 12 stops; a q-axis voltage detecting section 7 for setting a voltage command value of a q-axis which is applied to the q-axis orthogonal to a d-axis as the direction of a magnetic field generated by permanent magnets arranged in the rotor, when the motor stops; a two-phase/three-phase conversion section 3 for converting the voltage command value of the q-axis into a three-phase voltage command value of each of three phases; a three-phase/two-phase conversion section 6 for calculating a d-axis current of the d-axis based on a motor current applied in accordance with the application of the three-phase voltage command value; and a correction rotation angle setting section 8 for setting a correction rotation angle for correcting the initial rotation angle so that the d-axis current becomes zero when the d-axis current is not zero. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control device capable of correcting an attachment error of a rotation angle detection unit that detects a rotation angle of a rotor included in a three-phase motor.

  Conventionally, in the drive control of a three-phase motor, the motor current is coordinate-converted into a vector component of the d-axis that is the direction of the magnetic field generated by the permanent magnet of the rotor of the motor and the q-axis vector component orthogonal to the d-axis. Some motors perform rotation control (for example, Non-Patent Document 1). In the drive control of a three-phase motor similar to Non-Patent Document 1, the coil current is controlled according to the output torque of the motor by performing vector control that performs coordinate control on the coil current of the three-phase motor and performing feedback control. . A resolver is provided as a rotation angle detection unit that detects the rotation angle of the rotor in order to specify the position of the rotor in performing vector control.

Sugimoto Hidehiko, “Theory and Design of AC Servo Systems, From Basics to Software Servo”, General Electronic Publishing, p. 135-139

  As described above, the resolver is provided to specify the position of the rotor when performing vector control. However, when the resolver is mounted, if the resolver reference position (for example, zero point) and the rotor reference position (for example, zero point) are mounted out of alignment, and the three-phase motor vector control is performed with a mounting error included, There was a problem that the efficiency and output accuracy of the three-phase motor deteriorated.

  Moreover, when attaching a resolver to a three-phase motor, it is conceivable to use an attachment device that can attach the resolver to the rotor with high accuracy. However, when such an attachment device is used, there arises a problem that the manufacturing cost of the three-phase motor becomes high.

  In view of the above problems, an object of the present invention is to prevent the efficiency and output accuracy of a three-phase motor from deteriorating due to an attachment error between a rotor and a rotation angle detection unit that detects the position of the rotor. Is to provide a simple motor control device.

  The characteristic configuration of the motor control device according to the present invention for achieving the above object includes a rotation angle detector that detects a rotation angle of a rotor of the three-phase motor when the three-phase motor is stopped as an initial rotation angle, A q-axis voltage setting unit for setting a q-axis voltage command value to be applied to the q-axis orthogonal to the d-axis, which is the direction of the magnetic field generated by the permanent magnet disposed on the rotor, and the q-axis voltage command value A two-phase / three-phase converter that converts the three-phase voltage to a three-phase voltage command value for each phase, and the motor current that is energized to the three-phase motor in response to the application of the three-phase voltage command value at the time of the stop. A three-phase / two-phase converter that calculates the d-axis current of the d-axis and a correction rotation angle that corrects the initial rotation angle so that the d-axis current is zero when the d-axis current is not zero are set. And a correction rotation angle setting unit.

  With such a characteristic configuration, it is possible to operate with an offset of an attachment error when the rotation angle detector and the rotor are assembled. Therefore, it is possible to prevent the efficiency and output accuracy of the three-phase motor from deteriorating.

  The correction rotation angle setting unit preferably stores a correction rotation angle at which the d-axis current is zero.

  With such a configuration, the correction rotation angle for correcting the set attachment error of the angle detection unit is stored once, so there is no need to set the correction rotation angle again.

  The rotation angle detection unit detects a rotation angle of the rotor during rotation control of the three-phase motor, and is used for the rotation control based on the rotation angle of the rotor and the correction rotation angle. It is preferable to provide a rotation angle calculation unit that calculates.

  With such a configuration, the rotation control of the three-phase motor can be efficiently and accurately performed based on the control rotation angle obtained by correcting the mounting error between the angle detection unit and the rotor.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a motor control device 100 of the present invention. Here, the motor control device 100 according to the present invention corrects the mounting error that occurs when the rotation angle detection unit 11 that detects the rotation angle of the rotor of the three-phase motor 12 to be zero, and the correction is performed. A function for suitably controlling the three-phase motor 12 based on the rotation angle is provided. In order to realize such a function, the motor control apparatus 100 has a target current setting unit 1, an integration control unit 2, a two-phase / three-phase conversion unit 3, a PWM control unit 4, a frequency conversion unit 5, a three-phase / A two-phase conversion unit 6, a q-axis voltage setting unit 7, a correction rotation angle setting unit 8, a d-axis current determination unit 9, a rotation angle calculation unit 10, a rotation angle detection unit 11, and a three-phase motor 12 are configured ( Details will be described later).

  FIG. 2 is a diagram showing a configuration of an ECU 50 (described later), a frequency conversion unit 5 and a three-phase motor 12 in which the PWM control unit 4 is configured together with other functional units. Although not shown, the three-phase motor 12 includes a rotor including a permanent magnet and a stator that generates a magnetic field for applying a rotational force to the rotor. The stator includes U-phase, V-phase, and W-phase three-phase stator coils 12u, 12v, and 12w. One end of each stator coil is connected in common at an electrically neutral point and Y-connected. The other end of each stator coil is connected to the frequency converter 5. In the present embodiment, since the coil is provided in the stator, it is described as a stator coil. However, unless otherwise specified, the stator coil and the coil are used as being synonymous.

  The frequency converter 5 controls the three-phase motor 12 and converts a DC voltage into an AC voltage. The DC voltage is supplied from a power source 20 connected to the frequency conversion unit 5. As shown in FIG. 2, the frequency converter 5 includes high-side transistors Q1, Q3, and Q5 connected to the positive voltage side of the power source 20, and a low-side transistor Q2 connected to the negative voltage side of the power source 20. A total of six transistors Q1 to Q6 including Q4 and Q6 are formed. For example, when only the transistor Q1 and the transistor Q4 are turned on at the same time, a current flows from the power supply 20 to the second power supply line 22 via the first power supply line 21, the transistor Q1, the stator coil 12v, the stator coil 12w, and the transistor Q4. On the other hand, when only the transistor Q3 and the transistor Q2 are simultaneously turned on, a current flows from the power supply 20 to the second power supply line 22 via the first power supply line 21, the transistor Q3, the stator coil 12w, the stator coil 12v, and the transistor Q2. Thus, the frequency converter 5 converts the DC voltage output from the power supply 20 into an AC voltage.

  Further, the direction of the current flowing through the stator coil 12v and the stator coil 12w differs between when only the transistor Q1 and the transistor Q4 are turned on and when only the transistor Q3 and the transistor Q2 are turned on. Therefore, an electromagnetic force corresponding to the direction in which the current flows acts on each stator coil, and an attractive force and a repulsive force are generated between the electromagnetic force and a permanent magnet provided in the rotor. Therefore, the rotor can obtain rotational force by sequentially turning on the upper and lower pair transistors formed by the high-side transistor and the low-side transistor selected from the transistors Q1 to Q6.

  The transistors Q1 to Q6 are provided with diodes D1 to D6 so that the cathode terminal is connected to the collector terminal and the anode terminal is connected to the emitter terminal. Here, energy is stored in each stator coil during energization, but these diodes D1 to D6 are applied to peripheral components by back electromotive force generated due to the energy when the energization of each stator coil is stopped. It is arranged to prevent adverse effects.

  A series of control for the transistors Q1 to Q6 is performed by the PWM controller 4. As will be described in detail later, the PWM control unit 4 includes a target current setting unit 1, an integration control unit 2, a two-phase / three-phase conversion unit 3, a three-phase / two-phase conversion unit 6, a q-axis voltage setting unit 7, and a correction rotation. The ECU 50 is configured together with the angle setting unit 8, the d-axis current determination unit 9, and the rotation angle calculation unit 10 (see FIG. 1). The PWM control unit 4 controls the switching element included in the frequency conversion unit 5 by PWM (Pulse Width Modulation) control. In this embodiment, the switching elements included in the frequency conversion unit 5 correspond to the transistors Q1 to Q6. Therefore, the PWM control unit 4 operates the transistors Q1 to Q6 included in the frequency conversion unit 5 by PWM control.

  The three-phase motor 12 includes a rotation angle detection unit 11 that detects the rotation angle of the rotor of the three-phase motor 12. The rotation angle detection unit 11 converts the rotation angle of the rotor into an electrical angle θ and outputs a signal corresponding to the electrical angle θ. As such a rotation angle detector 11, it is preferable to use a resolver, for example. The signal output by the rotation angle detection unit 11 is transmitted to the rotation angle calculation unit 10. The rotation angle calculation unit 10 calculates the rotation angle of the rotor of the three-phase motor 12 based on the signal transmitted from the rotation angle detection unit 11. The ECU 50 monitors the rotation angle calculated by the rotation angle calculation unit 10 and the current between the frequency conversion unit 5 and each stator coil. In view of the overall configuration of the three-phase motor control device 100, the monitor is performed via each functional unit as shown in FIG. It does not cause a problem.

  The ECU 50 is configured by a microcomputer that operates at a low voltage such as 2.5 V or 3.3 V, for example. Therefore, depending on the current flowing through the transistors Q1 to Q6 and the electrical characteristics of the transistors Q1 to Q6, there is a possibility that the drive capability for turning on the transistors Q1 to Q6 may be insufficient. Therefore, a driver 51 (not shown in FIG. 1) for increasing the drive capability of the PWM signal of ECU 50 is arranged between ECU 50 and frequency converter 5. The driver 51 may be composed of a driver IC or a push-pull circuit assembled with transistors. Of course, when the drive capability of the PWM signal output from the ECU 50 is high, it is naturally possible to configure without the driver 51.

  Returning to FIG. 1, the target current setting unit 1 sets the target current from the total torque necessary for rotating the three-phase motor 12. The target current set by the target current setting unit 1 is transmitted to the integration control unit 2, and the output from the three-phase / two-phase conversion unit 6 is also transmitted to the integration control unit 2 as a feedback signal. The output from the three-phase / two-phase converter 6 corresponds to a calculation result calculated based on the motor current supplied to the three-phase motor 12.

  Here, the motor control apparatus 100 uses the motor currents iu, iv, and iw as vectors of the d axis that is the direction of the magnetic field generated by the permanent magnets of the rotor of the three-phase motor 12 and the q axis that is orthogonal to the d axis. Coordinate conversion is performed on the components Id and Iq to control the rotation of the three-phase motor 12. FIG. 3 is a diagram showing the principle of this coordinate transformation. The three-phase motor 12 shown in FIG. 3 includes a rotor 12r having a two-pole permanent magnet m, and the rotation angle of the rotor 12r and the electrical angle θ coincide with each other. FIG. 3A is a diagram showing the relationship between the motor current (three-phase alternating current) waveform and the electrical angle θ, and FIG. 3B shows the rotor 12r and the stator 12s at time t1 in FIG. It is a figure which shows the current vector before and after the positional relationship and coordinate transformation. FIG. 3B shows the electrical angle θ that is the magnetic pole position of the rotor 12r with reference to the U-phase magnetic pole position of the stator 12s.

  As shown in FIG. 3B, the direction of the magnetic field generated by the permanent magnet m is defined as the d axis, and the direction orthogonal to the d axis is defined as the q axis. As shown in FIG. 3A, torque is generated by passing three-phase alternating currents iu, iv, iw through the stator coils 12u, 12v, 12w according to the magnetic pole position of the rotor 12r. The vector ia (Ia) indicating the sum of the armature currents at the electrical angle θ at time t1 in FIG. 3A is zero because the W-phase current (W-phase motor current) iw is zero from FIG. 3A. , The vector sum of the U-phase current (U-phase motor current) iu and the V-phase current (V-phase motor current) iv. When the current vector ia at the electrical angle θ is decomposed with respect to the d-axis and the q-axis, a d-axis current Id and a q-axis current Iq are obtained. In this way, the three-phase motor currents iu, iv, iw are coordinate-converted into the d-axis current Id and the q-axis current Iq.

  Here, in particular, in a permanent magnet embedded synchronous motor, the inductance viewed from the stator coils 12u, 12v, and 12w varies depending on the relationship with the rotor 12r, that is, the relationship with the magnetic pole position. In the d-axis direction, which is the direction of the magnetic pole, the magnetic path is obstructed because it has a magnetic resistance proportional to the inverse of the permeability of the permanent magnet. On the other hand, in the q-axis direction, since the magnetic material such as silicon steel having a high permeability is passed, the value of the magnetic resistance is significantly smaller than that of the permanent magnet, and the magnetic path is not easily disturbed. For this reason, the q-axis inductance Lq is larger than the d-axis inductance Ld. Since the d-axis and the q-axis change in relation to the magnetic pole position when viewed from the stator coils 12u, 12v, and 12w, the inductance viewed from the stator coils 12u, 12v, and 12w changes.

  Therefore, in addition to the magnet torque (main torque) by the permanent magnet, reluctance torque is also generated due to the difference between the q-axis inductance Lq and the d-axis inductance Ld. When reluctance torque is not actively used, such as a surface magnet type synchronous motor, it is efficient to perform control with Id = 0. However, when using reluctance torque in a permanent magnet embedded synchronous motor or the like, it is more efficient to perform control with Id ≠ 0. In the permanent magnet embedded type synchronous motor, the operating point at which the maximum efficiency is obtained varies depending on the current phase angle β between the d-axis current Id and the q-axis current Iq shown in FIG. 4 (see equation (1)).

  The total torque T of the three-phase motor 12 is Pn: pole pair number, ψa: armature linkage flux, ia: armature current, Ld: d-axis inductance, Lq: q-axis inductance, β: current phase angle. It is represented by the torque equation shown in equation (2).

  In the formula (2), the first term in the braces indicates the magnet torque, and the second term indicates the reluctance torque. Moreover, since it is clear from FIG. 4 that the following equations (3) to (5) are obtained, the torque equation of the equation (2) can also be expressed as the following equation (6).

  As described above, the armature current Ia includes the d-axis current Id and the q-axis current Iq. Therefore, the torque equations shown in the equations (2) and (6) represent the torque of the three-phase motor 12 using the flux linkage, the d-axis and q-axis inductances, and the d-axis and q-axis currents. It can be said that it is an expression. The d-axis current Id and the q-axis current Iq are calculated by the three-phase / two-phase converter 6 described above.

  Returning to FIG. 1, the integration control unit 2 causes the three-phase / two-phase conversion unit 6 to perform coordinate conversion based on the target current set by the target current setting unit 1 and the motor current flowing through the three-phase motor 12. The d-axis current command value Idr and the q-axis current command value Iqr are calculated from the d-axis current Id and the q-axis current Iq obtained by the above. For example, the torque equation shown in the above equation (2) can be transformed into the equation of the armature current Ia. The integral control unit 2 calculates the d-axis current command value Idr and the q-axis current command value Iqr by substituting the target torque and other parameters to solve the deformed torque equation and performing vector decomposition by the phase angle β. Is possible. Alternatively, it is naturally possible to calculate the d-axis current command value Idr and the q-axis current command value Iqr from the equation (6). Further, the integration control unit 2 calculates a d-axis voltage command value Vdr and a q-axis voltage command value Vqr from the d-axis current command value Idr and the q-axis current command value Iqr based on the voltage equation. That is, the integral control unit 2 determines the d-axis voltage command value Vdr based on the target current set from the total torque required to rotate the three-phase motor 12 and the d-axis current Id and the q-axis current Iq. And the q-axis voltage command value Vqr can be calculated.

  The voltage equations representing the d-axis voltage Vd and the q-axis voltage Vq are: ψa: armature linkage flux, ω: angular velocity, Id: d-axis current, Iq: q-axis current, Ld: d-axis inductance, Lq: The q-axis inductance, Ra: armature resistance, p: differential operator is expressed as the following equation (7).

  Equation (7) is a voltage for driving the three-phase motor 12 using the interlinkage magnetic flux, the impedance of the stator coil of the three-phase motor 12 including the d-axis and q-axis inductances, and the d-axis and q-axis currents. It is clear that the voltage equation represents The integral control unit 2 substitutes the d-axis current command value Idr and the q-axis current command value Iqr and other parameters into the voltage equation shown in the equation (7), thereby obtaining the d-axis voltage Vd and the q-axis voltage Vq. calculate. The calculated d-axis voltage Vd and q-axis voltage Vq are output as a d-axis voltage command value Vdr and a q-axis voltage command value Vqr.

  The two-phase / three-phase conversion unit 3 converts the d-axis voltage command value Vdr and the q-axis voltage command value Vqr into three-phase voltage command values vu, vv, and vw for each of the three phases. The d-axis voltage command value Vdr and the q-axis voltage command value Vqr are calculated by the integration control unit 2 described above. The two-phase / three-phase converter 3 converts the d-axis voltage command value Vdr and the q-axis voltage command value Vqr to the opposite of the above-described coordinate conversion, thereby converting the three-phase voltage command values vu, vv, vw. Convert to Since this reverse conversion is the reverse conversion of the coordinate conversion described above with reference to FIGS. 3 and 4, detailed description of the conversion method is omitted.

  The calculation result obtained by the two-phase / three-phase converter 3 is input to the PWM controller 4 described above. Therefore, the PWM control unit 4 performs PWM control based on these inputs.

  The motor control apparatus 100 is based on the d-axis current Id and the q-axis current Iq obtained by the coordinate conversion of the three-phase / two-phase conversion unit 6 from the motor current flowing through the three-phase motor 12 as described above. The target current set by the target current setting unit 1 is feedback-controlled.

  Here, in the motor control as described above, the rotation angle detection unit 11 that detects the rotation angle of the rotor included in the three-phase motor 12 is attached to the rotor with high accuracy (that is, without including an installation error). It is assumed that However, it is not easy to attach the rotation angle detection unit 11 to the rotor without attaching errors. The motor control device 100 has a correction function for correcting an attachment error that occurs when the rotation angle detector 11 is attached. Hereinafter, this correction function will be described.

  The rotation angle detection unit 11 described above detects the rotation angle of the rotor of the three-phase motor 12 when the three-phase motor 12 is stopped after the rotation angle detection unit 11 is attached as the initial rotation angle. The rotation angle of the rotor at the time of the stop is treated as an initial rotation angle in correcting the above-described attachment error (details will be described later). Therefore, the rotation angle detector 11 is configured to store the initial rotation angle.

  The q-axis voltage setting unit 7 sets a q-axis voltage command value to be applied to the q-axis that is perpendicular to the d-axis, which is the direction of the magnetic field generated by the permanent magnet disposed on the rotor. Since the d-axis and the q-axis have been described with reference to FIG. 3, the description thereof is omitted here. The q-axis voltage setting unit 7 sets a q-axis voltage command value to be applied to the q-axis. The q-axis voltage command value is not particularly limited in the control related to the correction of the mounting error, and there is no problem as long as it is a predetermined value. A predetermined q-axis voltage command value set by the q-axis voltage setting unit 7 is transmitted to the 2-phase / 3-phase conversion unit 3.

  The two-phase / three-phase converter 3 converts the q-axis voltage command value into a three-phase voltage command value for each of the three phases. The q-axis voltage command value is transmitted from the q-axis voltage setting unit 7 described above. Here, in the control according to the correction, the d-axis voltage command value is zero. Therefore, the two-phase / three-phase conversion unit 3 converts the three-phase voltage command value using only the q-axis voltage command value in the control related to the correction. The converted three-phase voltage command value is transmitted to the PWM control unit 4 in the same manner as the normal rotation control described above.

  The PWM controller 4 performs PWM control of the three-phase motor 12 via the frequency converter 5 based on the three-phase voltage command value converted by the two-phase / 3-phase converter 3. Since this control is the same as the normal rotation control described above, description thereof is omitted.

  The three-phase / two-phase converter 6 calculates a d-axis d-axis current based on a motor current that is supplied to the three-phase motor 12 in response to application of the three-phase voltage command value when the three-phase motor 12 is stopped. Since the calculation of the d-axis current has been described above, a description thereof will be omitted. The d-axis current is a d-axis current that actually flows in the d-axis when the q-axis voltage command value set by the q-axis voltage setting unit 7 as described above is applied only to the q-axis. The d-axis current is transmitted to the d-axis current determination unit 9.

  The d-axis current determination unit 9 determines whether or not the d-axis current flowing through the d-axis is zero in response to the application of the q-axis voltage command value. Here, when there is no attachment error of the rotation angle detection unit 11 with respect to the rotor, the d-axis current becomes zero when the q-axis voltage command value is applied only to the q-axis. Therefore, when the d-axis current is not zero, there is an attachment error of the rotation angle detector 11 with respect to the rotor.

  When the d-axis current determination unit 9 determines that the d-axis current is zero, there is no error in attaching the rotation angle detection unit 11 to the rotor, so the correction rotation angle setting unit 8 sets the correction rotation angle to zero. Set. The corrected rotation angle is a rotation angle for correcting the initial rotation angle so that the d-axis current becomes zero when the q-axis voltage command value is applied only to the q-axis.

  The correction rotation angle setting unit 8 sets a correction rotation angle for correcting the initial rotation angle so that the d-axis current becomes zero when the d-axis current is not zero. Whether or not the d-axis current is zero is determined by the d-axis current determination unit 9 described above. If the d-axis current determination unit 9 determines that the d-axis current is not zero, the rotation angle detection unit 11 may have an attachment error with respect to the rotor. Therefore, the correction rotation angle setting unit 8 sets a correction rotation angle for correcting the initial rotation angle detected by the rotation angle detection unit 11. In this case, the correction rotation angle setting unit 8 cannot specify in advance how much the correction rotation angle is, and therefore sets the correction rotation angle to a predetermined value (for example, 1 degree). The corrected rotation angle set in this way is transmitted to the q-axis voltage setting unit 7.

  Similarly to the above, the q-axis voltage setting unit 7 sets a predetermined q-axis voltage command value and transmits it to the 2-phase / 3-phase conversion unit 3. In the same manner as described above, the d-axis current is calculated by the three-phase / two-phase conversion unit 6, and the d-axis current determination unit 9 determines whether the d-axis current after correction of the rotation angle is zero. This series of processing is repeated until the d-axis current becomes zero. In this way, a corrected rotation angle for correcting an attachment error of the rotation angle detection unit 11 is obtained. When the d-axis current becomes zero, the corrected rotation angle setting unit 8 stores a corrected rotation angle at which the d-axis current becomes zero.

  In the normal operation performed thereafter, the motor control device 100 uses the corrected rotation angle obtained in this way to perform offset correction so that the mounting error of the rotation angle detection unit 11 is zero, thereby correcting the three-phase motor. 12 rotation control is performed. That is, the rotation angle detection unit 11 detects the rotation angle of the rotor during the rotation control of the three-phase motor 12, and calculates the control rotation angle used for rotation control based on the rotation angle of the rotor and the correction rotation angle. . In this way, the motor control device 100 controls the rotation of the three-phase motor 12 to thereby control the three-phase motor 12 due to an attachment error between the rotor and the rotation angle detection unit 11 that detects the position of the rotor. It is possible to prevent deterioration in efficiency and output accuracy.

  Next, correction of the mounting error of the rotation angle detection unit 11 performed by the motor control device 100 will be described using a flowchart. FIG. 5 is a flowchart relating to the correction of the mounting error. First, the correction rotation angle setting unit 8 sets the correction rotation angle to zero and stores it (step # 01). The rotation angle detection unit 11 detects the rotation angle of the rotor when the three-phase motor 12 is stopped (step # 02).

  Next, the q-axis voltage setting unit 7 sets a predetermined voltage value as a q-axis voltage command value (step # 03). The q-axis voltage command value is transmitted to the 2-phase / 3-phase converter 3. The two-phase / three-phase converter 3 converts the transmitted q-axis voltage command value into a three-phase voltage command value (step # 04). In this case, the d-axis voltage command value is zero. The three-phase voltage command value converted by the two-phase / 3-phase converter 3 is transmitted to the PWM controller 4.

  The PWM control unit 4 energizes the three-phase motor 12 via the frequency conversion unit 5 based on the transmitted three-phase voltage command value (step # 05). Based on the motor current flowing through the three-phase motor 12, the three-phase / two-phase converter 6 calculates the d-axis current (step # 06). The calculated d-axis current is transmitted to the d-axis current determination unit 9.

  The d-axis current determination unit 9 determines whether or not the transmitted d-axis current is zero. If the d-axis current is zero (step # 07: Yes), the rotation angle stored in the correction rotation angle setting unit 8 is set as the correction rotation angle (step # 08). In this case, since the correction rotation angle is set to zero in step # 01, it becomes zero.

  On the other hand, if the d-axis current is not zero in step # 07 (step # 07: No), the corrected rotation angle setting unit 8 changes the corrected rotation angle and stores the changed corrected rotation angle (step # 07). 09). Then, the processing is continued from step # 03. Thereafter, the same processing is performed. If the d-axis current is zero in step # 07 (step # 07: Yes), the rotation angle stored in step # 09 is set as the correction rotation angle (step # 08). This process is continuously performed until the d-axis current becomes zero in Step # 07.

  In this way, the motor control device 100 sets a correction rotation angle that is offset and corrected so that the mounting error of the rotation angle detection unit 11 is zero. The correction rotation angle need only be set when the rotation angle detector 11 is attached. During normal operation of the motor control device 100, the rotation angle detected by the rotation angle detector 11 and the correction rotation angle are set. Based on the corrected rotation angle stored in the unit 8, a rotation angle without error is calculated and used. Specifically, the rotation angle detected by the rotation angle detection unit 11 in accordance with the rotation of the three-phase motor 12 and the correction rotation performed when the rotation angle detection unit 11 is attached are stored in the correction rotation angle setting unit 8. The corrected rotation angle is transmitted to the rotation angle calculation unit 10. The rotation angle calculation unit 10 adds these rotation angles and acquires a rotation angle with no error. Then, the acquired rotation angle is transmitted to the target current setting unit 1, and a target current for controlling the three-phase motor 12 is set. Therefore, it is possible to control the operation of the three-phase motor 12 with high efficiency and accuracy.

[Other Embodiments]
In the above-described embodiment, the correction control of the attachment error of the rotation angle detection unit 11 has been described as being performed when the rotation angle detection unit 11 is attached. However, the scope of application of the present invention is not limited to this. For example, the correction control according to the present invention may be performed every time the three-phase motor 12 is started, or may be performed every time the accumulated operation time of the three-phase motor 12 reaches a predetermined time. By performing the correction control in this way, it is possible to perform the operation control of the three-phase motor 12 in a state where there is always no attachment error of the rotation angle detection unit 11.

The figure which shows schematic structure of a motor control apparatus The figure which shows the structure of a PWM control part, a frequency conversion part, and a three-phase motor Diagram showing the principle of coordinate transformation Vector diagram explaining the phase angle of the armature current Flow chart for setting correction rotation angle

Explanation of symbols

1: target current setting unit 2: integration control unit 3: 2-phase / 3-phase conversion unit 4: PWM control unit 5: frequency conversion unit 6: 3-phase / 2-phase conversion unit 7: q-axis voltage setting unit 8: correction rotation Angle setting unit 9: d-axis current determination unit 10: rotation angle calculation unit 11: rotation angle detection unit 12: three-phase motor 50: ECU
100: Motor control device

Claims (3)

A rotation angle detector that detects a rotation angle of a rotor of the three-phase motor when the three-phase motor is stopped as an initial rotation angle;
A q-axis voltage setting unit for setting a q-axis voltage command value to be applied to the q-axis orthogonal to the d-axis, which is the direction of the magnetic field generated by the permanent magnet disposed in the rotor;
A two-phase / three-phase converter that converts the q-axis voltage command value into a three-phase voltage command value for each of the three phases;
A three-phase / two-phase converter that calculates a d-axis current of the d-axis based on a motor current energized to the three-phase motor in response to application of the three-phase voltage command value at the time of the stop;
A correction rotation angle setting unit for setting a correction rotation angle for correcting the initial rotation angle so that the d-axis current is zero when the d-axis current is not zero;
A motor control device comprising:   The motor control device according to claim 1, wherein the correction rotation angle setting unit stores a correction rotation angle at which the d-axis current is zero. The rotation angle detection unit detects the rotation angle of the rotor during rotation control of the three-phase motor;
The motor control device according to claim 1, further comprising: a rotation angle calculation unit that calculates a control rotation angle used for the rotation control based on the rotation angle of the rotor and the correction rotation angle.

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