JP2015119565A - Inverter device and inverter control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter device that efficiently performs flux-weakening control, and an inverter control method.SOLUTION: An inverter device includes a torque command unit, a current command generation unit 12, a flux-weakening current command vector generation unit, a current control unit 16, and an inverter 19. The torque command unit generates a torque command indicating output torque of a permanent magnet motor 3. The current command generation unit generates a basic current command vector on the basis of the torque command generated by the torque command unit. The flux-weakening current command vector generation unit generates a flux-weakening current command vector for flux-weakening control that is orthogonal to a current phase angle of a current flowing through the permanent magnet motor. The current control unit determines a voltage command indicating a voltage applied to the permanent magnet motor on the basis of the basic current command vector and the flux-weakening current command vector. The inverter generates a voltage applied to the permanent magnet motor on the basis of the voltage command determined by the current control unit.

Description

  Embodiments described herein relate generally to an inverter device and an inverter control method.

  A control unit of a permanent magnet reluctance motor that generates a magnet torque by a permanent magnet and a reluctance torque by a magnetic saliency may perform magnetic flux weakening control so that the motor terminal voltage is equal to or lower than the maximum voltage of the inverter. When performing the flux weakening control, the control unit of the permanent magnet reluctance motor sets a target point of the current command value vector on the equal torque curve. However, the equal torque curve differs depending on the motor, and there is a problem that the controller of the permanent magnet reluctance motor must set the equal torque curve for each motor.

Patent No. 4008724

  In order to solve the above-described problems, an inverter device and an inverter control method that efficiently perform flux-weakening control are provided.

  According to the embodiment, the inverter device includes a torque command unit, a current command generation unit, a flux-weakening current command vector generation unit, a current control unit, and an inverter. The torque command unit generates a torque command indicating the output torque of the permanent magnet motor. The current command generation unit generates a basic current command vector based on the torque command generated by the torque command unit. The weak flux current command vector generation unit generates a weak flux current command vector for weak flux control that is orthogonal to the current phase angle of the current flowing through the permanent magnet motor. The current control unit determines a voltage command indicating a voltage to be applied to the permanent magnet motor based on the basic current command vector and the weak magnetic flux current command vector. The inverter generates a voltage to be applied to the permanent magnet motor based on the voltage command determined by the current control unit.

  An inverter device comprising:

FIG. 1 is a block diagram illustrating a configuration example of a motor drive system according to the first embodiment. FIG. 2 is a diagram illustrating an example of a current instruction vector generated by the current command unit according to the first embodiment. FIG. 3 is a block diagram illustrating a configuration example of the flux-weakening control unit according to the first embodiment. FIG. 4 is a diagram illustrating an example of flux-weakening control according to the first embodiment. FIG. 5 is a block diagram illustrating a configuration example of a motor drive system according to the second embodiment.

(First embodiment)
Hereinafter, it demonstrates in detail, referring drawings.
FIG. 1 is a block diagram illustrating a configuration example of a motor drive system 1 according to the first embodiment.
As shown in FIG. 1, the motor drive system 1 includes an inverter device 2, a permanent magnet reluctance motor 3, a phase angle detector 4, and the like.

  The inverter device 2 supplies a three-phase AC voltage to the permanent magnet reluctance motor to drive the permanent magnet reluctance motor 3. The inverter device 2 will be described in detail later.

  The permanent magnet reluctance motor 3 is a three-phase AC motor that generates a combined torque of a magnet torque by a permanent magnet and a reluctance torque by magnetic saliency. The permanent magnet reluctance motor 3 is driven by being supplied with a three-phase AC voltage from the inverter device 2. The permanent magnet reluctance motor 3 includes, for example, a permanent magnet as a rotor (rotor) and an electromagnet as a stator (stator). The permanent magnet reluctance motor 3 generates a magnetic field by passing a current through the stator. The rotor of the permanent magnet reluctance motor 3 is rotated by the generated magnetic field. The number of motor pole pairs of the permanent magnet reluctance motor 3 is not limited to a specific value.

  The phase angle detector 4 detects the rotational phase angle θ (magnet magnetic flux direction) of the rotor of the permanent magnet reluctance motor 3. The phase angle detector 4 is, for example, a resolver or an encoder. If the inverter device 2 includes means for estimating the rotational phase angle θ, the phase angle detection unit 4 may be omitted. The phase angle detector 4 transmits the detected rotational phase angle θ to the inverter device 2.

Next, the inverter device 2 will be described.
As shown in FIG. 1, the inverter device 2 includes a speed control unit 11, a current command unit 12, current command value addition units 13 a and 13 b, a current phase angle calculation unit 14, a flux weakening control unit 15, a current control unit 16, coordinates A conversion unit 17, a PWM modulation unit 18, an inverter 19, current detection units 20a and 20b, a coordinate conversion unit 21, a speed calculation unit 22, and the like are provided.

  The speed control unit 11 generates a torque to be generated in the permanent magnet reluctance motor 3 based on the indicated rotation speed ω * indicating the rotation speed of the rotor that is instructed from the outside and the rotation speed ω of the rotor of the permanent magnet reluctance motor 3. To decide. The speed controller 11 acquires the rotational speed ω of the rotor of the permanent magnet reluctance motor 3 from the speed calculator 22. The speed control unit 11 transmits a torque command value T * indicating the determined torque to the current command unit 12. For example, when ω *> ω, the speed control unit 11 may transmit a torque command value T * larger than the current torque to the current command unit 12. In addition, when ω * <ω, the speed control unit 11 may transmit a torque command value T * smaller than the current torque to the current command unit 12.

  The current command unit 12 generates a basic current command vector based on the torque command value T * transmitted from the speed control unit 11. The basic current command vector is a vector having the basic current command values id0 * and iq0 * as components. The basic current command values id0 * and iq0 * are both current values before the flux-weakening control is performed. The basic current command value id0 * is a current value flowing in the d-axis direction of the stator of the permanent magnet reluctance motor 3. The d-axis is the direction of magnetic flux created by the magnetic poles of the rotor. The basic current command value iq0 * is a current value flowing in the q-axis direction of the stator of the permanent magnet reluctance motor 3. The q axis is an axis that is electrically and magnetically orthogonal to the d axis.

FIG. 2 is a diagram illustrating an example of a basic current command vector generated by the current command unit 12.
In the coordinates shown in FIG. 2, the x-axis indicates the current flowing in the d-axis direction of the stator, and the y-axis indicates the current flowing in the q-axis direction of the stator.

  The basic current command vector 41 indicates a basic current command value that flows in the d-axis direction and a basic current command value that flows in the q-axis direction. That is, the end point of the basic current command vector 41 is (id0 *, iq0 *). Further, the angle of the basic current command vector 41 is represented by β.

  The constant current circle 42 indicates a combination of id and iq that makes the current flowing through the stator constant. That is, if the end point of the basic current command vector 41 is on the constant current circle 42, the basic current command value is constant at any point.

  The equal torque curve 43 shows a combination of id and iq that makes the torque of the permanent magnet reluctance motor 3 constant. That is, if the end point of the basic current command vector 41 is on the equal torque curve 43, the torque of the permanent magnet reluctance motor 3 based on the basic current command value is constant at any point.

The current command unit 12 sets a basic current command vector 41 at a point where the equal torque curve 43 and the constant current circle 42 are in contact with each other in order to reduce the current flowing through the stator.
The current command unit 12 calculates basic current command values id0 * and iq0 * according to the following formulas 1 to 3, for example.

  Here, Φm is a magnetic flux, Ld is a d-axis inductance, and Lq is a q-axis inductance. I * represents a current amplitude and is determined according to the torque command value T *.

  The current command unit 12 transmits the basic current command values id0 * and iq0 * to the current command value adding units 13a and 13b, respectively.

  The current command value adding unit 13a calculates the current command value id * by adding the basic current command value id0 * and the weak magnetic flux current command value idfw *. The current command value adding unit 13b calculates the current command value iq * by adding the basic current command value iq0 * and the weak magnetic flux current command value iqfw *. The current command value adding units 13a and 13b transmit the current command values id * and iq * to the current phase angle calculating unit 14 and the current control unit 16, respectively. Here, a vector having the weak flux current command value idfw * and the weak flux current command value iqfw * as components is referred to as a weak flux current command vector. The flux weakening current command vector will be described in detail later.

The current phase angle calculation unit 14 calculates the current phase angle β based on the basic current command vector and the flux weakening current command vector. That is, the current phase angle calculation unit 14 calculates the current phase angle β based on the current command values id * and iq * received from the current command value addition units 13a and 13b, respectively. The current phase angle β is an angle from the d-axis of the current command value vector (vector indicated by (id *, iq *)).
When the current phase angle calculator 14 calculates the current phase angle β, the current phase angle β is weakened and transmitted to the magnetic flux controller 15.

  The weakening magnetic flux control unit 15 is based on the current phase angle β transmitted by the current phase angle calculation unit 14 and the voltage command values vd * and vq * transmitted by the current control unit 16, and the weakening magnetic flux current command values idfw * and iqfw. * Is generated. The weakening magnetic flux control unit 15 will be described in detail later.

  Based on the current response values id and iq transmitted by the coordinate conversion unit 21 and the current command values id * and iq * transmitted by the current command value adding units 13a and 13b, the current control unit 16 determines the voltage command value vd * and Generate vq *. Voltage command values vd * and vq * indicate voltages applied to the d-axis and q-axis of the stator, respectively. Current response values id and iq indicate currents flowing in the d-axis and q-axis of the stator, respectively. For example, the current control unit 16 may generate the voltage command values vd * and vq * by comparing the current response values id and iq with the current command values id * and iq *. The current controller transmits the generated current command values id * and iq * to the magnetic flux controller 15 and the coordinate converter 17.

  The coordinate conversion unit 17 determines the voltage command value vu * in the three-phase fixed coordinate system based on the voltage command values vd * and vq * transmitted by the current control unit 16 and the rotational phase angle θ transmitted by the phase angle detection unit 4. , Vv * and vw *. For example, the coordinate conversion unit 17 includes a voltage command value vu * as a voltage command value indicating a voltage applied to the first phase, a voltage command value vv * as a voltage command value indicating a voltage applied to the second phase, and A voltage command value vw * is generated as a voltage command value indicating a voltage applied to the third phase. The coordinate conversion unit 17 transmits the generated voltage command values vu *, vv *, and vw * to the PWM modulation unit 18.

  The PWM modulation unit 18 generates a gate command including ON / OFF commands for switching elements corresponding to the respective phases of the inverter 19 based on the voltage command values vu *, vv *, and vw * transmitted from the coordinate conversion unit 17. . The PWM modulation unit 18 transmits the generated gate command to the inverter 19.

  The inverter 19 outputs a voltage to be applied to each phase of the permanent magnet reluctance motor 3 based on the gate command transmitted by the PWM modulation unit 18. That is, the inverter 19 outputs a voltage based on the basic current command vector and the magnetic flux current command vector to each phase of the permanent magnet reluctance motor 3. For example, the inverter 19 generates a voltage to be applied to each phase of the permanent magnet reluctance motor 3 by switching ON / OFF of a switching element built in the inverter 19 based on the gate command. For example, the inverter 19 generates a voltage u as a voltage applied to the first phase, a voltage v as a voltage applied to the second phase, and a voltage w as a voltage applied to the third phase. The inverter 19 outputs the generated voltages v, u, and w to the permanent magnet reluctance motor 3.

  The current detection unit 20 measures a current flowing through two phases of the three-phase AC current flowing through the permanent magnet reluctance motor 3 or all currents. The current detection unit 20 transmits a current value indicating the detected current to the coordinate conversion unit 21. Here, the current detection unit 20 includes current detection units 20a and 20b. The current detection unit 20a detects a current flowing in a phase (for example, the first phase) to which the voltage u is applied. The current detection unit 20 a transmits a current value iu indicating the detected current to the coordinate conversion unit 21. In addition, the current detection unit 20b detects a current flowing in a phase to which the voltage w is applied (for example, the third phase). The current detection unit 20 b transmits a current value iw indicating the detected current to the coordinate conversion unit 21.

  The coordinate conversion unit 21 generates current response values id and iq based on the current values iu and iw transmitted by the current detection unit 20 and the rotational phase angle θ transmitted by the phase angle detection unit 4. Current response values id and iq indicate currents flowing in the d-axis and q-axis of the stator, respectively. The coordinate conversion unit 21 transmits the generated current response values id and iq to the current control unit 16.

  The speed calculation unit 22 calculates the rotational speed ω of the rotor based on the rotational phase angle θ transmitted by the phase angle detection unit 4. For example, the speed calculation unit 22 calculates the rotation speed ω by differentiating the rotation phase angle θ with respect to time. The speed calculation unit 22 transmits the calculated rotation speed ω to the speed control unit 11.

Next, the flux weakening control unit 15 will be described.
The weakening magnetic flux control unit 15 performs the weakening magnetic flux control as described above. The flux weakening control is a process for preventing the voltage amplitude value V of the inverter 19 from becoming larger than the limit voltage value Vlim that the inverter 19 can output. Here, V is expressed by the following equations 4 to 6.

  Here, Vd is a voltage applied in the d-axis direction of the stator, and Vq is a voltage applied in the q-axis direction of the stator. However, in Equations 5 and 6, for the sake of simplicity, the resistance component is omitted and only the induced voltage component is shown.

  The flux weakening control unit 15 determines a magnetic flux current command vector. The magnetic flux current command vector is a vector set in order to make the voltage amplitude value V smaller than the limit voltage value Vlim. The magnetic flux current command vector is determined so that the voltage amplitude value V is less than or equal to the limit voltage value Vlim when the voltage command values vd * and vq * are generated based on the current command vector generated by adding to the basic current command vector. Is done.

FIG. 3 is a block diagram illustrating a configuration example of the flux weakening control unit 15.
As shown in FIG. 3, the weak flux control unit 15 includes an amplitude calculation unit 31, a voltage control unit 32, a weak flux direction calculation unit 33, a weak flux current command generation unit 34, and the like.

  The amplitude calculator 31 calculates the voltage amplitude value V output from the inverter 19 based on vd * and vq * transmitted from the current controller 16. For example, the amplitude calculator 31 calculates the voltage amplitude value V output from the inverter 19 according to Equation 4. The amplitude calculation unit 31 transmits the calculated voltage amplitude value V to the voltage control unit 32.

  The voltage control unit 32 determines the weakening depth dfw based on the limit voltage value Vlim and the voltage amplitude value V transmitted by the amplitude calculation unit 31. The weakening depth dfw is the length of the magnetic flux current command vector. For example, when the voltage amplitude value V is equal to or less than the limit voltage value Vlim, the voltage control unit 32 may determine the weakening depth dfw as 0. In addition, for example, the voltage control unit 32 may determine the weakening depth dfw to a larger value as the voltage amplitude value V exceeds the limit voltage value Vlim.

The voltage control unit 32 may acquire the limit voltage value Vlim from an external device, or may store the limit voltage value Vlim in an internal memory or the like. Or you may calculate like Formula 7 from an inverter DC voltage.

  The voltage control unit 32 transmits the determined weakening depth dfw to the weakening magnetic flux current command generation unit 34.

  The voltage control unit 32 is composed of, for example, a PI controller.

  The weak magnetic flux direction calculator 33 determines the direction (weak magnetic flux direction) θfw of the magnetic flux current command vector based on the current phase angle β transmitted by the current phase angle calculator 14. Specifically, the magnetic flux weakening direction calculation unit 33 determines the direction perpendicular to the current phase angle β as the magnetic flux weakening direction θfw.

  In other words, the magnetic flux weakening direction calculation unit 33 determines the direction in which the voltage amplitude value V decreases among the two directions orthogonal to the current phase angle β as the magnetic flux weakening direction θfw. That is, the magnetic flux weakening direction calculation unit 33 determines the direction in which the current flowing in the d-axis direction decreases (the direction in which the current flows negatively) as the magnetic flux weakening method θfw.

  For example, the magnetic flux weakening direction calculation unit 33 determines the angle obtained by adding 90 degrees (π / 2) to the current phase angle β as the magnetic flux weakening direction θfw. The weakening magnetic flux direction calculation unit 33 transmits the determined weakening magnetic flux direction θfw to the weakening magnetic flux current command generation unit 34.

  The weak flux current command generator 34 generates the weak flux current commands idfw * and iqfw * based on the weak depth dfw and the weak flux direction θfw transmitted by the voltage controller 32. The flux weakening current command idfw * is an x-axis (d-axis) component of the flux current command vector. Further, the weak flux current command iqfw * is a y-axis (q-axis) component of the flux current command vector.

The flux weakening current command generation unit 34 includes a cosine generation unit 51, a sine generation unit 52, and integration units 53a and 53b.
The cosine generator 51 calculates the cosine value of the weak magnetic flux direction θfw from the weak magnetic flux direction θfw transmitted by the weak magnetic flux direction calculator 33. The cosine generation unit 51 transmits the calculated cosine value to the integration unit 53a.

  The sine generator 52 calculates the sine value of the weak magnetic flux direction θfw from the weak magnetic flux direction θfw transmitted by the weak magnetic flux direction calculator 33. The sine generation unit 52 transmits the calculated sine value to the integration unit 53b.

The accumulating unit 53a calculates a weak flux current command value idfw * based on the weakening depth dfw transmitted by the voltage control unit 32 and the cosine value transmitted by the cosine generating unit 51. The accumulating unit 53a transmits the calculated weak magnetic flux current command value idfw * to the current command value adding unit 13a.
Based on the weakening depth dfw transmitted by the voltage control unit 32 and the sine value transmitted by the sine generation unit 52, the integrating unit 53b calculates the weakening flux current command value iqfw *. Accumulation unit 53b transmits the calculated flux-weakening current command value iqfw * to current command value addition unit 13b.

  FIG. 4 is a diagram illustrating an example of a magnetic flux current command vector generated by the flux weakening control unit 15. FIG. 4 is a diagram in which the magnetic flux current command vector 44 is added to FIG. In FIG. 4, the magnetic flux current command vector 44 is described starting from the end point of the basic current command vector 41.

As shown in FIG. 4, the magnetic flux current command vector 44 is orthogonal to the basic current command vector 41. Further, the magnetic flux current command vector 44 decreases the current flowing in the q-axis direction and increases the d-axis current in the minus direction that cancels the d-axis magnet magnetic flux, so that the voltage amplitude value V is decreased.
The length of the magnetic flux current command vector 44 is a weakening depth dfw.
The current command vector having the current command values id * and iq * supplied to the current control unit 16 as a component is a vector indicating the end point of the magnetic flux current command vector 44.

Next, an operation example of the motor drive system 1 will be described.
First, the inverter device 2 receives an instruction rotational speed ω * from the outside. The speed control unit 11 of the inverter device 2 acquires the instruction rotational speed ω *. When the command rotation speed ω * is acquired, the speed control unit 11 generates a torque command value T * based on the command rotation speed ω * and the rotation speed ω. When the torque command value T * is generated, the speed control unit 11 transmits the generated torque command value T * to the current command unit 12.

  The current command unit 12 receives the torque command value T * from the speed control unit 11. When receiving the torque command value T *, the current command unit 12 generates basic current command values id0 * and iq0 * based on the received torque command value T *. When the basic current command values id0 * and iq0 * are generated, the current command unit 12 transmits the generated basic current command values id0 * and iq0 * to the current command value adding units 13a and 13b, respectively.

  Current command value addition units 13a and 13b receive basic current command values id0 * and iq0 *, respectively. When the basic current command values id0 * and iq0 * are received, the current command value adders 13a and 13b add the basic current command values id0 * and iq0 * and the weak flux current command values idfw * and iqfw *, respectively. By adding both, the current command value adding units 13a and 13b obtain current command values id * and iq *. When the current command values id * and iq * are obtained, the current command value addition units 13a and 13b transmit the obtained current command values id * and iq * to the current phase angle calculation unit 14 and the current control unit 16.

  The current phase angle calculator 14 receives the current command values id * and iq *. When the current command values id * and iq * are received, the current phase angle calculation unit 14 calculates the current phase angle β. When the current phase angle β is calculated, the current phase angle calculation unit 14 weakens the calculated current phase angle β and transmits it to the magnetic flux control unit 15.

  The current control unit 16 receives the current command values id * and iq *. When receiving the current command values id * and iq *, the current control unit 16 generates the voltage command values vd * and vq *. When the voltage command values vd * and vq * are generated, the current control unit 16 transmits the generated voltage command values vd * and vq * to the magnetic flux control unit 15 and the coordinate conversion unit 17.

Next, an operation example of the flux weakening control unit 15 will be described.
The flux weakening control unit 15 receives the current phase angle β and the voltage command values vd * and vq *. The amplitude calculation unit 31 of the flux weakening control unit 15 acquires the voltage command values vd * and vq *. When the voltage command values vd * and vq * are acquired, the flux weakening control unit 15 calculates the voltage amplitude value V. When the voltage amplitude value V is calculated, the amplitude calculation unit 31 transmits the calculated voltage amplitude value V to the voltage control unit 32.

  The voltage control unit 32 receives the voltage amplitude value V. When receiving the voltage amplitude value V, the voltage control unit 32 determines the weakening depth dfw. When the weakening depth dfw is determined, the voltage control unit 32 transmits the determined weakening depth dfw to the weakening magnetic flux current command generation unit 34.

  Further, the magnetic flux weakening direction calculating unit 33 of the magnetic flux weakening control unit 15 acquires the current phase angle β. When the current phase angle β is acquired, the flux-weakening direction calculation unit 33 calculates the flux-weakening direction θfw. When the magnetic flux weakening direction θfw is calculated, the magnetic flux weakening direction calculating unit 33 transmits the calculated magnetic flux weakening direction θfw to the magnetic flux weakening current command generating unit 34.

  The weakening magnetic flux current command generation unit 34 receives the weakening depth dfw and the weakening magnetic flux direction θfw. The cosine generator 51 and the sine generator 52 of the flux-weakening current command generator 34 each acquire the flux-weakening direction θfw. When the flux weakening direction θfw is acquired, the cosine generator 51 and the sine generator 52 calculate the cosine value and the sine value of the flux weakening direction θfw, respectively. When the cosine value and the sine value are respectively calculated, the cosine generation unit 51 and the sine generation unit 52 transmit the cosine value and the sine value to the integration units 53a and 53b, respectively.

  The accumulating unit 53a acquires the weakening depth dfw and the cosine value. When acquiring the weakening depth dfw and the cosine value, the integrating unit 53a generates the weakening magnetic flux current command value idfw *. When the weak magnetic flux current command value idfw * is generated, the integrating unit 53a transmits the generated weak magnetic flux current command value idfw * to the current command value adding unit 13a.

  Similarly, the integrating unit 53b acquires the weakening depth dfw and the cosine value. When obtaining the weakening depth dfw and the sine value, the integrating unit 53b generates the weakening magnetic flux current command value iqfw *. When weakening magnetic flux current command value iqfw * is generated, integrating unit 53b transmits generated weakening magnetic flux current command value iqfw * to current command value adding unit 13b.

  When integrating units 53a and 53b transmit flux-weakening current command values idfw * and iqfw * to current command value adding units 13a and 13b, respectively, flux-weakening control unit 15 ends the operation.

  The current command value adding units 13a and 13b add the weak magnetic flux current command values idfw * and iqfw * to the basic current command values id0 * and iq0 *, respectively. When both are added, the current command value addition units 13 a and 13 b transmit the current command values id * and iq * obtained by the addition to the current control unit 16.

Upon receiving the current command values id * and iq *, the current control unit 16 weakens the voltage command values vd * and vq * and transmits them to the magnetic flux control unit 15 and the coordinate conversion unit 17.
The weakening magnetic flux control unit 15 may perform the weakening magnetic flux control again.

  The coordinate conversion unit 17 receives the voltage command values vd * and vq *. When the voltage command values vd * and vq * are received, the coordinate conversion unit 17 generates the voltage command values vu *, vv *, and vw *. When the voltage command values vu *, vv *, and vw * are generated, the coordinate conversion unit 17 transmits the generated voltage command values vu *, vv *, and vw * to the PWM modulation unit 18.

  The PWM modulation unit 18 receives the voltage command values vu *, vv *, and vw *. When the voltage command values vu *, vv * and vw * are received, the PWM modulation unit 18 generates a gate command. When the gate command is generated, the PWM modulation unit 18 transmits the generated gate command to the inverter 19.

The inverter 19 receives a gate command. When receiving the gate command, the inverter 19 supplies the voltages u, v, and w to the permanent magnet reluctance motor 3.
The permanent magnet reluctance motor 3 rotates the rotor by the voltages u, v and w supplied from the inverter 19. The phase angle detector 4 detects the rotational phase angle θ of the rotor.

When the rotation phase angle θ is detected, the phase angle detection unit 4 transmits the detected rotation phase angle θ to the coordinate conversion unit 17, the coordinate conversion unit 21, and the speed calculation unit 22.
Further, the current detection unit 20 detects current response values iu and iw. When the current response values iu and iw are detected, the current detection unit 20 transmits the detected current response values iu and iw to the coordinate conversion unit 21.

  The coordinate conversion unit 21 receives the current response values iu and iw and the rotation phase angle θ. When the current response values iu and iw and the rotation phase angle θ are received, the coordinate conversion unit 21 generates current response values id and iq. When the current response values id and iq are generated, the coordinate conversion unit 21 transmits the generated current response values id and iq to the current control unit 16.

  Further, the speed calculation unit 22 acquires the rotation phase angle θ. When the rotational phase angle θ is acquired, the speed calculator 22 calculates the rotational speed ω. When the rotation speed ω is calculated, the speed calculation unit 22 transmits the calculated rotation speed ω to the speed control unit 11.

The inverter device 2 repeats the above operation to drive the permanent magnet reluctance motor 3.
The motor drive system 1 may include another permanent magnet motor having saliency instead of the permanent magnet reluctance motor 3.

  Moreover, each part of the inverter apparatus 2 may be implement | achieved by software. Moreover, a part or all of each part of the inverter apparatus 2 may be implement | achieved by hardware.

  The inverter device configured as described above can set the magnetic flux current command vector along the equal torque curve. Therefore, the inverter device can perform a stable and effective flux-weakening control while outputting a torque with good followability to the torque command value. Further, the inverter device does not need to set an equal torque curve for each motor and torque. Therefore, versatility is improved in the inverter device.

(Second Embodiment)
Next, a second embodiment will be described.
The motor drive system 1 according to the second embodiment is that the current phase angle calculation unit 14 calculates the current phase angle β based on the current flowing between the inverter 19 and the permanent magnet reluctance motor 3. This is different from the motor drive system 1 according to the above. Therefore, about other points, the same numerals are attached and detailed explanation is omitted.

FIG. 5 shows a configuration example of the motor drive system 1 according to the second embodiment.
The coordinate conversion unit 21 further transmits the generated current response values id and iq to the current phase angle calculation unit 14.

  The current phase angle calculation unit 14 calculates the current phase angle β based on the current flowing between the inverter 19 and the permanent magnet reluctance motor 3. That is, the current phase angle calculation unit 14 calculates the current phase angle β based on the current response values id and iq received from the coordinate conversion unit 21. The current phase angle calculation unit 14 weakens the calculated current phase angle β and transmits it to the magnetic flux control unit 15.

  The inverter device configured as described above can calculate the current phase angle β without causing a delay due to current control. Therefore, the inverter device can perform the weakening magnetic flux control with better followability.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Motor drive system, 2 ... Inverter device, 3 ... Permanent magnet reluctance motor, 12 ... Current command part, 14 ... Current phase angle calculating part, 15 ... Weak magnetic flux control part , 16 ... current control unit, 19 ... inverter, 31 ... amplitude calculation unit, 32 ... voltage control unit, 33 ... weakening magnetic flux direction calculation unit, 34 ... weakening magnetic flux current command generation Part, 41 ... basic current command vector, 44 ... magnetic flux current command vector.

Claims (8)

In the inverter device for driving the permanent magnet motor,
A torque command unit that generates a torque command indicating an output torque of the permanent magnet motor;
A current command generating unit that generates a basic current command vector based on the torque command generated by the torque command unit;
A weak magnetic flux current command vector generating unit that generates a weak magnetic flux current command vector for weak magnetic flux control orthogonal to the current phase angle of the current flowing through the permanent magnet motor;
A current control unit that determines a voltage command indicating a voltage to be applied to the permanent magnet motor based on the basic current command vector and the flux-weakening current command vector;
Based on the voltage command determined by the current control unit, an inverter that generates a voltage to be applied to the permanent magnet motor;
An inverter device comprising: The flux-weakening current command vector generation unit is
A voltage control unit that determines a length of the flux-weakening current command vector based on the voltage command determined by the current control unit;
A weak magnetic flux direction calculation unit that sets the direction of the weak magnetic flux current command vector in a direction orthogonal to the current phase angle;
Comprising
The inverter device according to claim 1. The current command generation unit sets the basic current command vector at a point where an equal torque curve of the permanent magnet motor and a constant current circle are in contact with each other.
The inverter device according to claim 1 or 2. further,
A current phase angle calculation unit for calculating the current phase angle based on the basic current command vector and the flux-weakening current command vector;
The inverter device according to any one of claims 1 to 3. further,
A current phase angle calculation unit for calculating the current phase angle based on a current flowing between the inverter and the permanent magnet motor;
The inverter device according to any one of claims 1 to 3. The torque command unit generates the torque command based on an instruction rotational speed from an external device.
The inverter device according to any one of claims 1 to 5. The voltage control unit determines the length of the flux-weakening current command vector so that a voltage amplitude value of the inverter is a predetermined value or less;
The weakening magnetic flux direction calculation unit sets the direction of the weakening magnetic flux current command vector in the direction in which the voltage amplitude value of the inverter decreases.
The inverter device according to any one of claims 1 to 6. An inverter control method for supplying power to a permanent magnet motor,
Generate a torque command indicating the output torque of the permanent magnet motor,
A basic current command vector is generated based on the torque command,
Generating a flux-weakening current command vector for flux-weakening control orthogonal to the current phase angle of the current flowing through the permanent magnet motor;
Based on the basic current command vector and the flux weakening current command vector, determine a voltage command indicating a voltage to be applied to the permanent magnet motor,
Based on the voltage command, a voltage to be applied to the permanent magnet motor is generated.
Inverter control method.

Images