JP2013187931A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device that achieves a stable and high-speed transient response characteristic by starting weak magnetic flux control swiftly when a command torque or a command current increases.SOLUTION: A motor control device includes: three-phase current detection means; angular velocity detection means; a conversion part for converting a three-phase current into a d-axis current Id and a q-axis current Iq; a calculation part for converting a command torque into a command d-axis current Idand a command q-axis current Iq; a voltage vector calculation part 6 for calculating a command d-axis voltage Vdand a command q-axis voltage Vq; a command voltage conversion part; and electric power conversion means, wherein the voltage vector calculation part 6 includes a weak magnetic flux control part 63 for calculating a required voltage Vreq, which is required to compensate for a q-axis curent deviation ΔIq where the q-axis current Iq is subtracted from the command q-axis current Iq, and when the required voltage Vreq exceeds a predetermined limit voltage Vlim, performing control so that the command d-axis current Idis increased to a negative side (adding an adjustment amount Iadj that is a negative value).

Description

  The present invention relates to a control device that performs feedback control of a current supplied to an armature winding of a three-phase synchronous motor, and more particularly to a motor control device that improves transient response characteristics when performing flux-weakening control.

  In recent years, a technique for applying an inverter to a control device for a three-phase synchronous motor has become widespread, and control performance has been greatly improved as compared with the old state. In the control device to which the inverter is applied, the phase of the applied rectangular wave voltage is controlled by detecting and feeding back the current of each phase flowing through the armature winding, based on the command torque or command current from the outside. In many cases, the current is controlled by controlling the effective voltage value by a pulse width modulation (PWM) method. In this type of control, the rotational phase of the rotor is detected, the angular velocity is calculated, and the calculation is generally performed on the dq coordinate axis with reference to the rotational position of the rotor magnet. A technical example is disclosed in Document 2.

  The control device for a permanent magnet synchronous motor disclosed in Patent Document 1 includes a second d-axis and q-axis current command value calculated from a first d-axis and q-axis current command value and a current detection value, and The output voltage value of the power converter that drives the permanent magnet synchronous motor is controlled according to the frequency command value. And it has the field-weakening command calculation part which makes the integral calculation value of the deviation of an output voltage command value and an output voltage value a 1st d-axis current command value. Thus, it is described that a highly accurate and highly responsive motor torque can be realized even in a field weakened field. That is, since the power converter cannot output more than the maximum output voltage of the drive power supply, if the output voltage command value becomes too large, it can no longer follow the command value. At this time, a large torque can be obtained by flowing a negative d-axis current by the flux weakening control.

  Moreover, the synchronous motor control device disclosed in Patent Document 2 includes a power converter that applies an AC voltage, a speed detector that detects a rotation speed, a current detector that detects a three-phase current, and a three-phase current. 3-phase / 2-phase coordinate conversion unit for converting to dq-axis current, d-axis and q-axis current control unit, 2-phase / 3-phase coordinate conversion unit for calculating 3-phase voltage command, and d-axis current command calculation Department. The d-axis current command calculation unit includes a d-axis current command limiting unit that limits the d-axis current command according to the motor speed. The d-axis current command limiter calculates the maximum q-axis voltage from the d-axis command voltage and the maximum output voltage, compares the maximum q-axis voltage with the q-axis command voltage, and if the latter exceeds the former, Is used to increase the d-axis command current in the direction in which the magnetic flux is weakened. As a result, it is expected that an optimum d-axis current command can be created and saturation of the voltage commands Vd * and Vq * can be prevented. Also in the technical example of Patent Document 2, the flux-weakening control is used as described above, and the voltage equation is considered in a steady state.

JP 2006-20411 A JP 2008-86138 A

  By the way, in the control device of Patent Document 1, when calculating the d-axis command current, the previous d-axis command voltage is fed back and used. Therefore, the magnetic flux weakening control is not started until after the deviation between the output voltage command value and the output voltage value occurs, and there is a delay time in the control. For this reason, it cannot be said that the control is sufficient for a transient current change when the command torque or the command current increases. Also, looking at the arithmetic expression, only the steady state is considered, in other words, the inductance component of the armature winding is not considered, and the transient response is not dealt with.

  Also in the control device of Patent Document 2, after calculating the q-axis voltage command, this is fed back to calculate the d-axis current command, and then the d-axis voltage command is calculated, resulting in a delay in the calculation. . Since the calculation delay directly leads to a delay in response time, it cannot be said to be sufficient for controlling the transient response when the command torque or the command current changes.

  The present invention has been made in view of the problems of the background art described above. When the command torque or the command current increases, the magnetic flux control is started promptly so that a stable and high-speed transient response characteristic can be obtained. Providing a realized motor control apparatus is a problem to be solved.

  The invention of the motor control device according to claim 1 for solving the above-described problem is to detect a three-phase current flowing in the armature winding of a three-phase synchronous motor having a magnet in a rotor and an armature winding in a stator. Current detecting means for detecting, angular speed detecting means for detecting the angular speed at which the rotor rotates, and the detected three-phase current, the d-axis current on the dq coordinate axis and the q-axis on the basis of the rotational position of the magnet of the rotor A detection current conversion unit for converting into current, a current command calculation unit for converting external command torque or command current into a command d-axis current and a command q-axis current on the dq coordinate axis, the d-axis current, and the q-axis A voltage vector computing unit that computes a command voltage represented by a command d-axis voltage and a command q-axis voltage on the dq coordinate axis based on the current, the command d-axis current, and the command q-axis current; Axial voltage and said finger A motor control device comprising: a command voltage converter that converts a q-axis voltage into a three-phase voltage; and a power converter that generates the three-phase voltage and applies it to the armature winding, wherein the voltage vector calculation The unit calculates a required voltage required to compensate for a q-axis current deviation obtained by subtracting the q-axis current from the command q-axis current, and the command is output when the required voltage exceeds a predetermined limit voltage. A weakening magnetic flux control unit that controls to increase the d-axis current to the negative side is included.

  According to a second aspect of the present invention, in the first aspect, the flux-weakening control unit calculates the required voltage by multiplying the q-axis current deviation by a q-axis inductance and dividing by a control cycle time.

  According to a third aspect of the present invention, in the first or second aspect, the flux-weakening control unit increases the command d-axis current to the negative side in response to an excess of the required voltage exceeding the limit voltage. Determine the adjustment amount.

  According to a fourth aspect of the present invention, in the first aspect, the voltage vector calculation unit subtracts the q-axis current from the q-axis command current to obtain a q-axis current deviation, and is proportional to the q-axis current deviation. A q-axis calculating unit for calculating the command q-axis voltage by integral control; and calculating the required voltage by multiplying the q-axis current deviation by a q-axis inductance and dividing by a control cycle time. In response to the excess exceeding the value, the flux-weakening control unit that determines the adjustment amount for increasing the command d-axis current to the negative side, and the d-axis current after taking the adjustment amount into consideration for the d-axis command current A d-axis operation unit that obtains a d-axis current deviation by subtraction and calculates the command d-axis voltage by proportional-integral control based on the d-axis current deviation.

  The main object of the present invention is to obtain a voltage command by reducing a delay time caused by calculation in order to cope with saturation of an applied voltage caused by a transient increase in current command. Further, in the transient current increase, as shown in the motor voltage equation, the inductance component of the armature winding has a great influence on the transient response. Therefore, in the present invention, the d-axis current obtained by correcting the increase in the applied voltage required for increasing the current in consideration of the inductance component is obtained, and the applied voltage is started by starting the weakening magnetic flux control that weakens the magnetic flux instantaneously. Saturation is avoided, and stable and fast transient response characteristics are maintained.

  In the motor control device according to the first aspect of the present invention, the flux-weakening control unit of the voltage vector calculation unit calculates the required voltage required to compensate for the q-axis current deviation obtained by subtracting the q-axis current from the command q-axis current. Control is performed to increase the command d-axis current to the negative side when the required voltage exceeds a predetermined limit voltage. Therefore, when the required voltage exceeds the limit voltage by increasing the command torque or command current, the magnetic flux control starts immediately and the actual applied voltage increases to the limit voltage and instantaneously saturates. Can be avoided. Thereby, the current value corresponding to the command can be reached in a short time, and a stable and fast transient response characteristic can be realized.

  In the invention according to claim 2, since the flux weakening control unit calculates the required voltage by multiplying the q-axis current deviation by the q-axis inductance and dividing by the control cycle time, the inductance component of the armature winding is considered. The required voltage can be calculated with high accuracy.

  In the invention according to claim 3, since the flux-weakening control unit determines the adjustment amount for increasing the command d-axis current to the negative side in response to the excess of the required voltage exceeding the limit voltage, the actual applied voltage Can be reliably avoided.

  In the invention according to claim 4, the voltage vector calculation unit corresponds to the q-axis calculation unit that calculates the command q-axis voltage by proportional-integral control based on the q-axis current deviation, and the excess where the required voltage exceeds the limit voltage And a weak flux control unit for determining an adjustment amount for increasing the command d-axis current to the negative side, and after taking the adjustment amount into consideration for the d-axis command current, the d-axis current is subtracted to obtain a d-axis current deviation, and a proportional integral A d-axis calculation unit that calculates a command d-axis voltage by control. The present invention has a remarkable effect of realizing a stable and high-speed transient response characteristic by combining the method of calculating the command voltage by proportional integral control as described above and the flux weakening control unit.

It is a block diagram showing the whole motor control unit composition of an embodiment. It is a block diagram which shows the internal structure of a voltage vector calculating part. It is a block diagram which shows the internal structure of the voltage vector calculating part of the motor control apparatus of a prior art. In embodiment and the prior art, it is a figure which shows the result of having simulated the change of d-axis current and q-axis current when an electric current command increases.

  A motor control device 1 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating an overall configuration of a motor control device 1 according to an embodiment. The motor control device 1 is configured to include a computer that is operated by software. A control target is a three-phase synchronous motor 9 and control amounts are three-phase voltages Vu, Vv, and Vw applied to the motor 9.

The three-phase synchronous motor 9 is an embedded magnet synchronous motor configured by embedding a magnet in a rotor core (not shown) and winding an armature winding around a stator core (not shown), and is not limited thereto. The motor control device 1 performs an internal calculation to control the three-phase voltages Vu, Vv, Vw so as to output from the motor 9 a torque equal to the command torque Tq ^* received from the outside. The superscript * attached to the sign of the command torque Tq ^* means the value of the command. Hereinafter, * also means the value of the command in the other signs. The motor control device 1 includes two current detection units 2v and 2w, an angular velocity detection unit 3, a detection current conversion unit 4, a current command calculation unit 5, a voltage vector calculation unit 6, a command voltage conversion unit 7, and a power conversion unit 8 It consists of

  The two current detection means 2v, 2w are respectively provided on the V-phase input line 91v and the W-phase input line 91w of the three-phase input lines 91u, 91v, 91w connected to the armature winding of the motor 9. ing. The current detection means 2v and 2w can be configured using, for example, a known current transformer or shunt resistor, and detect the V-phase current Iv and the W-phase current Iw and send the detection signals to the detection current conversion unit 4. Output. Note that the detection current conversion unit 4 calculates the third-phase U-phase current Iu using the fact that the vector sum of the three-phase currents Iu, Iv, and Iw is zero.

  The angular velocity detection means 3 includes an angle sensor 31 that detects the rotational phase θ of the rotor of the three-phase synchronous motor 9 and an angular velocity conversion unit 32 that converts the rotational phase θ into an angular velocity ω of an electrical angle. The angle sensor 31 can be configured using, for example, a known resolver and sends the detected rotational phase θ to the angular velocity conversion unit 32. The angular velocity conversion unit 32 calculates the angular velocity ω by dividing the change amount of the rotational phase θ obtained by the two detections by the elapsed time (corresponding to time differentiation), and sends the detected current conversion unit 4 and the command voltage conversion unit 7 to each other. Output.

  The detection current conversion unit 4 uses a known conversion formula using the angular velocity ω to convert the three-phase currents Iu, Iv, and Iw to the d-axis current Id and the q-axis current on the dq coordinate axis based on the rotation position of the rotor magnet. Iq is converted and output to the voltage vector calculation unit 6.

The current command calculation unit 5 converts the command torque Tq ^* received from the outside into a command d-axis current Id ^* and a command q-axis current Iq ^* and commands the voltage vector calculation unit 6. This conversion process can be performed using, for example, a preset conversion table. Alternatively, the command d-axis current Id ^* and the command q-axis current Iq ^* may be directly received from the outside as the command current and passed to the voltage vector calculation unit 6.

The voltage vector calculation unit 6 calculates the command d-axis voltage Vd ^* and the command q-axis voltage Vq ^* based on the d-axis current Id, the q-axis current Iq, the command d-axis current Id ^* , and the command q-axis current Iq ^*. The command voltage conversion unit 7 is commanded. As described in detail later, the voltage vector calculation unit 6 includes a d-axis calculation unit 61 and a q-axis calculation unit 62 that calculate the command d-axis voltage Vd ^* and the command q-axis voltage Vq ^* by proportional-integral control, and the present invention. The magnetic flux weakening control unit 63 is provided.

The command voltage conversion unit 7 converts the command d-axis voltage Vd ^* and the command q-axis voltage Vq ^* into a three-phase voltage Vu, Vv, Vw by a known conversion formula using the angular velocity ω, and sends the command to the power conversion means 8. To do.

  The power conversion means 8 actually generates three-phase voltages Vu, Vv, Vw and applies them to the armature winding. The power conversion means 8 can be constituted by, for example, a battery and a pulse width modulation circuit (not shown). The pulse width modulation circuit switches and controls the positive / negative polarity of the DC output voltage of the battery, controls the energization time width by pulse width modulation (PWM), adjusts the effective voltage value, and commands the three-phase voltage Vu, Vv and Vw are generated. Here, the three-phase voltages Vu, Vv, and Vw do not exceed the DC output voltage of the battery, and the DC output voltage corresponds to the limit voltage Vlim of the present invention. Even if the three-phase voltages Vu, Vv, and Vw having a magnitude exceeding the DC output voltage are commanded, the actual applied voltage is saturated at the limit voltage Vlim.

  Next, a voltage equation expressed on the dq coordinate axis will be described. As is well known, in the three-phase synchronous motor 9 with a built-in magnet, the following voltage equation is established.

In general, in a steady state where the command torque Tq ^* is constant, the d-axis current Id that does not contribute to the generation of torque in the voltage equation is controlled to approximately zero, while the q-axis current Iq is the magnitude of the command torque Tq ^* . It is controlled to a substantially constant value corresponding to.

When the above voltage equation is expanded and displayed with respect to the q-axis voltage Vq, an equation obtained by adding four terms as shown in the following equation is obtained.
Vq = ωLd · Id + R · Iq + pLq · Iq + ωΨ
Here, considering immediately after the command torque Tq ^* increases from the steady state, the first term (ωLd · Id) on the right side can be ignored because the d-axis current is substantially zero. The second term (R · Iq) on the right side means a required voltage required to flow a large q-axis current Iq corresponding to a large command torque Tq ^* against the winding resistance R component. The third term (pLq · Iq) on the right side means a required voltage required to flow a large q-axis current Iq against the q-axis inductance Lq component. Further, the fourth term (ωΨ) on the right side is a voltage required to resist the armature reaction generated by the magnetic flux Ψ of the magnet.

Therefore, when the command torque Tq ^* increases, an increase in the q-axis voltage Vq corresponding to the second term and the third term on the right side is required, and the applied voltage may be saturated at the limit voltage Vlim. On the other hand, by performing weakening magnetic flux control that reduces the magnetic flux Ψ of the magnet equivalently and reduces the fourth term on the right side, the increase in the q-axis voltage Vq can be suppressed and voltage saturation can be avoided. That is, the d-axis current Id is increased in the negative direction, and a current magnetic field is generated so as to cancel the magnetic flux Ψ of the magnet. Furthermore, by adjusting the magnitude of the adjustment amount Iadj of the negative d-axis current Id corresponding to the magnitude of the excess Vover in which the q-axis voltage Vq calculated by increasing the q-axis current Iq exceeds the limit voltage Vlim, Voltage saturation can be avoided reliably.

  Based on such an idea, the internal configuration of the voltage vector calculation unit 6 is determined in the embodiment. FIG. 2 is a block diagram showing an internal configuration of the voltage vector calculation unit 6. As shown in the figure, the voltage vector calculation unit 6 includes a q-axis calculation unit 62, a flux weakening control unit 63, and a d-axis calculation unit 61.

The q-axis calculation unit 62 includes an adder 621 and a q-axis proportional integration controller 622 (q-axis PI controller) shown on the lower side of the block diagram of FIG. 2, and performs calculation from the left side to the right side. Do. The adder 621 subtracts the q-axis current Iq from the q-axis command current Iq ^* to obtain the q-axis current deviation ΔIq, and multiplies the q-axis proportional integral controller 622 (q-axis PI controller) and the flux weakening control unit 63. Output to the device 631. The q-axis proportional integral controller 622 uses the q-axis current deviation ΔIq to determine and output a command q-axis voltage Vq ^* (t) using the following calculation formula.

The flux weakening control unit 63 includes a multiplier 631, an adder 632, and an adjustment amount controller 633 shown in the center of the block diagram of FIG. 2, and performs calculation from the lower side to the upper side. Multiplier 631 multiplies q-axis current deviation ΔIq by coefficient K to obtain required voltage Vreq, and outputs the result to adder 632. The coefficient K is a value obtained by dividing the q-axis inductance Lq by the control cycle time ΔT, and the required voltage Vreq is obtained by the following equation.
Vreq = Lq × ΔIq / ΔT
This equation agrees with the following general equation showing the relationship between the voltage v of the inductance L and the current i.
v = L × di / dt

The adder 632 subtracts the required voltage Vreq from the limit voltage Vlim to obtain an excess voltage Vover (negative value), and outputs it to the adjustment amount controller 633. The adjustment amount controller 633 determines an adjustment amount Iadj that increases the command d-axis current Id ^* to the negative side, corresponding to the excess Vover. As qualitatively shown in FIG. 2, the adjustment amount controller 633 sets the adjustment amount Iadj to zero when the excess Vover is not generated. The adjustment amount controller 633 obtains an adjustment amount Iadj (negative value) that increases to the negative side in response to the excess Vover (negative value) when the excess Vover is generated, and the d-axis calculation unit 61. To the adder 611. The characteristics of the adjustment amount controller 633 are set in advance corresponding to the motor 9 to be controlled.

The d-axis calculation unit 61 includes an adder 611, an adder 612, and a d-axis proportional integration controller 613 (d-axis PI controller) shown on the upper side of the block diagram of FIG. The operation is performed. The adder 611 adds the adjustment amount Iadj (negative value) to the d-axis command current Id ^* calculated adjustments d-axis command current ^{Id **,} and outputs to the adder 612. The adder 612 subtracts the d-axis current Id from the adjusted d-axis command current Id ^** to obtain a d-axis current deviation ΔId, and outputs it to the d-axis proportional integration controller 613 (d-axis PI controller). The d-axis proportional integration controller 613 calculates and outputs a command d-axis voltage Vd ^* (t) by the following arithmetic expression.

  Next, the operation and effect of the motor control device 1 of the embodiment will be described in comparison with the prior art. The motor control device of the prior art is different from the embodiment in the internal configuration of the voltage vector calculation unit 6X, and the other parts 2v, 2w, 3, 4, 5, 7, and 8 are the same as those in the embodiment. FIG. 3 is a block diagram showing an internal configuration of the voltage vector calculation unit 6X of the conventional motor control device. As shown in the figure, the voltage vector calculation unit 6 </ b> X according to the prior art includes a d-axis calculation unit 65 and a q-axis calculation unit 66, and does not include the flux-weakening control unit 63.

In the conventional d-axis calculation unit 65, an adder 651 subtracts the d-axis current Id from the d-axis command current Id ^* to obtain a d-axis current deviation ΔId, and a d-axis proportional integral controller 652 (d-axis PI control). Device). The d-axis proportional integration controller 652 obtains and outputs a command d-axis voltage Vd ^* (t) by proportional integration control similar to that of the embodiment.

Similarly, in the conventional q-axis calculation unit 66, the adder 661 subtracts the q-axis current Iq from the q-axis command current Iq ^* to obtain the q-axis current deviation ΔIq, and the q-axis proportional integration controller 662 (q Output to the axis PI controller). The q-axis proportional integration controller 662 obtains and outputs a command q-axis voltage Vq ^* (t) by proportional integration control similar to that of the embodiment.

FIG. 4 is a diagram illustrating a result of simulating changes in the d-axis currents Id1 and Id2 and the q-axis currents Iq1 and Iq2 when the current command (q-axis current command Iq ^* ) increases in the embodiment and the prior art. is there. The horizontal axis in FIG. 4 represents time t (sec), the vertical axis represents current (%), the d-axis current Id1 and the q-axis current Iq1 in the embodiment are shown by solid lines, and the d-axis current Id2 and the q-axis current in the prior art. Iq2 is indicated by a broken line. As conditions for the simulation, the case where the q-axis current command Iq ^* increased from 0% to 100% at the time t0 and the d-axis current command Id ^* was 0% and remained unchanged was set.

As a result of the simulation, in the embodiment, the d-axis current Id1 increases in the negative direction from the time t0 and the flux-weakening control is started, and the negative value of the d-axis current Id1 continues until the time t1. On the other hand, the q-axis current Iq1 increases substantially linearly from the time t0, and after the time t1, the q-axis current Iq1 approaches 100% of the q-axis current command Iq ^* , and the increasing trend slows down to approximately 100% at the time t2. Has reached.

  On the other hand, in the prior art, the d-axis current Id2 slightly increases in the positive direction from time t0 and the flux-weakening control is not performed, and the positive value of the d-axis current Id2 continues for a long time. On the other hand, the q-axis current Iq2 increases almost linearly from the time t0 in the same manner as in the embodiment, but the increasing trend starts earlier. For this reason, the q-axis current Iq2 reaches approximately 100% at time t3 which is considerably delayed from time t2 in the embodiment.

  Therefore, comparing the two, the embodiment reached the current value of 100% corresponding to the command current in a shorter time, and realized a high-speed transient response characteristic. Further, in the embodiment, an unstable phenomenon such as overshoot or vibration of the q-axis current Iq1 does not occur, and it responds stably in response to an increase in the command current.

  In the prior art that performs the flux-weakening control exemplified in Patent Document 1, the flux-weakening control is started only after the three-phase voltages Vu, Vv, and Vw commanded from the power converter 7 exceed the limit voltage Vlim. Will do. On the other hand, in the present invention, when the command current increases, the flux weakening control can be started quickly. In other words, while the conventional technique is feedback control by detecting voltage saturation, the present invention can be referred to as feedforward control for predicting voltage saturation, and enables faster response characteristics than the prior art.

Furthermore, the flux-weakening control unit 63 of the motor control device 1 according to the embodiment calculates the required voltage Vreq by multiplying the q-axis current deviation ΔIq by the q-axis inductance Lq and dividing by the control cycle time ΔT. The required voltage Vreq can be calculated with high accuracy in consideration of the inductance component. In addition, the flux-weakening control unit 63 determines the adjustment amount Iadj that increases the command d-axis current Id ^* to the negative side in response to the excess Vover where the required voltage Vreq exceeds the limit voltage Vlim. It is possible to reliably avoid saturation of the applied three-phase voltages Vu, Vv, and Vw.

  In addition, the voltage vector calculation unit 6 is composed of the proportional-integral control d-axis calculation unit 61 and q-axis calculation unit 62 and the flux-weakening control unit 63, thereby realizing a stable and high-speed transient response characteristic. The effect of doing becomes remarkable.

  The d-axis calculation unit 61 and the q-axis calculation unit 62 are not limited to the proportional-integral control method, and other control methods can also be used. Various other applications and modifications are possible for the present invention.

1: Motor control device 2v, 2w: Current detection means 3: Angular velocity detection means 31: Angle sensor 32: Angular velocity conversion unit 4: Detection current conversion unit 5: Current command calculation unit 6: Voltage vector calculation unit
61: d-axis calculation unit 611: adder 612: adder
613: d-axis proportional integration controller 62: q-axis calculation unit 621: adder
622: q-axis proportional integral controller 63: Weak magnetic flux controller 631: Multiplier
632: Adder 633: Adjustment amount controller 7: Command voltage conversion unit 8: Power conversion means 9: Three-phase synchronous motor 6X: Conventional voltage vector calculation unit 65: d-axis calculation unit 66: q-axis calculation unit Tq ^* : Command torque Id ^* : Command d-axis current Iq ^* : Command q-axis current Vd ^* : Command d-axis voltage Vq ^* : Command q-axis voltage Vu, Vv, Vw: Three-phase voltage Iv, Iw: V-phase and W-phase current θ: rotational phase ω: angular velocity Id: d-axis current Id ^** : adjustment d-axis command current ΔId: d-axis current deviation Iq: q-axis current deviation ΔIq: q-axis current deviation Vlim: limit voltage Vreq: required voltage Vover: excess Iadj: Adjustment amount

Claims (4)

Current detecting means for detecting a three-phase current flowing in the armature winding of a three-phase synchronous motor having a magnet in a rotor and an armature winding in a stator;
Angular velocity detecting means for detecting an angular velocity at which the rotor rotates;
A detected current converter for converting the detected three-phase current into a d-axis current and a q-axis current on a dq coordinate axis with reference to the rotational position of the magnet of the rotor;
A current command calculation unit for converting an external command torque or command current into a command d-axis current and a command q-axis current on the dq coordinate axis;
Based on the d-axis current, the q-axis current, the command d-axis current, and the command q-axis current, a voltage for calculating a command voltage expressed by the command d-axis voltage and the command q-axis voltage on the dq coordinate axis A vector operation unit;
A command voltage converter that converts the command d-axis voltage and the command q-axis voltage into a three-phase voltage;
A power control means for generating the three-phase voltage and applying it to the armature winding, and a motor control device comprising:
The voltage vector calculation unit calculates a required voltage required to compensate for a q-axis current deviation obtained by subtracting the q-axis current from the command q-axis current, and the required voltage exceeds a predetermined limit voltage. A motor control device including a flux-weakening control unit that controls to increase the command d-axis current to the negative side sometimes.   The motor control device according to claim 1, wherein the flux-weakening control unit calculates the required voltage by multiplying the q-axis current deviation by a q-axis inductance and dividing by a control cycle time.   3. The motor control device according to claim 1, wherein the flux-weakening control unit determines an adjustment amount for increasing the command d-axis current to the negative side in response to an excess of the required voltage exceeding the limit voltage. . The voltage vector calculation unit according to claim 1,
A q-axis calculating unit that subtracts the q-axis current from the q-axis command current to obtain a q-axis current deviation, and calculates the command q-axis voltage by proportional-integral control based on the q-axis current deviation;
The required voltage is calculated by multiplying the q-axis current deviation by the q-axis inductance and dividing by the control cycle time, and the command d-axis current is negative in response to an excess of the required voltage exceeding the limit voltage. A flux-weakening control unit that determines an adjustment amount to be increased to the side,
The d-axis that calculates the command d-axis voltage by proportional-integral control based on the d-axis current deviation by subtracting the d-axis current after taking the adjustment amount into consideration for the d-axis command current. A motor control device.

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