JP5305933B2 - Motor drive system - Google Patents

Description

  The present invention relates to a motor drive system including an inverter that drives a variable magnetic flux motor capable of changing a magnetic flux.

  In recent years, a variable magnetic flux motor that can change a magnetic flux by magnetizing a low coercive force permanent magnet is known (see, for example, Patent Documents 1 and 2). Further, a motor drive system including a variable magnetic flux motor is disclosed (for example, see Patent Document 3).

JP 2006-280195 A JP 2006-220557 A JP 2008-125201 A

  However, when the motor drive system as described above is applied to HEV (Hybrid Electric Vehicle) or EV (Electric Vehicle), etc., depending on the state of charge of the battery as a DC power source, the voltage drop due to the current flowing through the inverter, etc. The DC voltage input to the inverter that drives the variable magnetic flux motor may fluctuate.

  The maximum value of the motor terminal voltage varies due to the influence of this voltage variation. The maximum value of the motor terminal voltage affects the performance of the motor at high speed. Specifically, even at the same rotational speed, the higher the maximum value of the motor terminal voltage, the higher the torque. That is, the motor output varies depending on the state of the voltage input to the inverter. Therefore, when the inverter input voltage is lowered, the motor may not be able to make an expected performance request.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a motor drive system that can be operated with high robustness against fluctuations in voltage input to an inverter that drives a motor.

Motor drive system according to an aspect of the present invention includes a DC power supply, and a permanent magnet synchronous motor having a permanent magnet Ru changing the magnetic flux, and converts the DC power supplied to the AC power from the DC power source, An inverter for driving the permanent magnet synchronous motor, a magnetic flux variable means for calculating a magnetizing current command value for outputting a magnetizing current for changing the magnetic flux of the permanent magnet from the inverter to the permanent magnet synchronous motor, and an input to the inverter DC voltage detecting means for detecting a DC voltage , magnetic flux estimating means for estimating the magnetic flux of the permanent magnet, rotational speed calculating means for calculating the rotational speed of the permanent magnet synchronous motor, and calculating a magnetization correction amount, said corrected magnetization current command value in the magnetization correction amount includes a variable flux control unit for the control for changing the magnetic flux of the permanent magnet, the variable flux control hand Is a torque command which is a command for correcting the rotational speed calculated by the rotational speed calculating means and controlling the torque of the permanent magnet synchronous motor based on the DC voltage detected by the DC voltage detecting means, The magnetization correction amount is calculated based on the rotation speed corrected by the rotation speed correction means and the magnetic flux estimated by the magnetic flux estimation means .

  ADVANTAGE OF THE INVENTION According to this invention, the motor drive system which can drive | operate highly robust with respect to the fluctuation | variation of the voltage input into the inverter which drives a motor can be provided.

1 is a block diagram showing a configuration of a motor drive system according to a first embodiment of the present invention. The block diagram which shows the structure of the magnetization current calculating part which calculates the magnetization correction amount of the variable magnetic flux control part which concerns on 1st Embodiment. The coordinate diagram which shows the magnetizing current table which concerns on 1st Embodiment. The coordinate diagram which shows the relationship between the torque of the motor drive system which concerns on 1st Embodiment, and DC voltage. The coordinate diagram which shows the relationship between the magnetic flux and torque of the motor drive system which concern on 1st Embodiment. The coordinate diagram for demonstrating the principle of control by the magnetizing current table of the motor drive system which concerns on 1st Embodiment. The block diagram which shows the structure of the motor drive system which concerns on the 2nd Embodiment of this invention. The block diagram which shows the structure of the magnetization current calculating part of the variable magnetic flux control part which concerns on 2nd Embodiment. The block diagram which shows the structure of the motor drive system which concerns on the 3rd Embodiment of this invention. The block diagram which shows the structure by the magnetic flux command calculating part and variable magnetic flux control part which concern on 3rd Embodiment. The characteristic view which shows the magnetization characteristic of the variable magnet which concerns on 3rd Embodiment. The block diagram which shows the structure of the magnetic flux command calculating part and variable magnetic flux control part which concern on the 4th Embodiment of this invention. The characteristic view which shows the magnetization characteristic of the variable magnet for calculating the magnetization correction amount in the magnetization current instruction | command calculating part which concerns on 4th Embodiment. The block diagram which shows the structure of the motor drive system which concerns on the 5th Embodiment of this invention. The block diagram which shows the structure of the magnetic flux command calculating part and variable magnetic flux control part which concern on 5th Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a motor drive system 1 according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part in subsequent figures, the detailed description is abbreviate | omitted, and a different part is mainly described. In the following embodiments, the same description is omitted.

  The motor drive system 1 includes an inverter 2, a DC power source 3, a variable magnetic flux motor 4, a rotation angle sensor 5, a DC voltage detector 7, AC current detectors 8U and 8W, and a control unit 10. Yes.

  The variable magnetic flux motor 4 is a permanent magnet synchronous motor that can change the magnetic flux. A fixed magnet and a variable magnet are incorporated in the rotor of the variable magnetic flux motor 4. The fixed magnet is a magnet that does not change the magnetic flux density (the amount of magnetic flux). Therefore, a magnetic material having a high coercive force is used for the fixed magnet. The variable magnet is a magnet that changes the magnetic flux density (magnetic flux amount). Therefore, a magnetic material having a low coercive force is used for the variable magnet.

  The inverter 2 converts the DC power supplied from the DC power source 3 into three-phase AC power. The inverter 2 supplies the converted AC power to the variable magnetic flux motor 4. The inverter 2 drives the variable magnetic flux motor 4 by outputting AC power to the variable magnetic flux motor 4.

  The rotation angle sensor 5 detects the rotation angle of the variable magnetic flux motor 4. The rotation angle sensor 5 outputs the detected rotation angle θ to the control unit 10.

  The DC voltage detector 7 detects a DC voltage (inverter input voltage) input to the inverter 2. The DC voltage detector 7 outputs the detected DC voltage VFC to the control unit 10.

  AC current detector 8U detects U-phase current Iu output from inverter 2. The AC current detector 8U outputs the detected U-phase current Iu as a signal to the control unit 10. AC current detector 8 </ b> W detects W-phase current Iw output from inverter 2. The AC current detector 8W outputs the detected W-phase current Iw to the control unit 10.

  The control unit 10 is based on the rotation angle θ detected by the rotation angle sensor 5, the DC voltage VFC detected by the DC voltage detector 7, and the AC currents Iu and Iw detected by the AC current detectors 8U and 8W, respectively. Thus, the inverter 2 is controlled. The control unit 10 controls driving of the variable magnetic flux motor 4 and magnetic flux through the inverter 2.

  Next, control of the inverter 2 by the control unit 10 will be described.

  The control unit 10 includes a pseudo-differentiator 11, a magnetic flux command calculation unit 12, a current reference calculation unit 13, a coordinate conversion unit 14, a voltage command calculation unit 15, a coordinate conversion unit 16, a PWM circuit 17, a gate, The command generator 18, the magnetization request generator 19, the current magnetic flux calculator 20, the variable magnetic flux controller 21, and the adder AD <b> 1 are provided.

  The pseudo differentiator 11 differentiates the rotation angle θ input from the rotation angle sensor 5 to calculate a motor rotation speed (rotor rotation frequency, inverter frequency) ω1. The pseudo differentiator 11 outputs the calculated motor rotation speed ω1 to the magnetic flux command calculation unit 12, the voltage command calculation unit 15, the current magnetic flux calculation unit 20, and the variable magnetic flux control unit 21.

  An operation command Run * is input to the magnetic flux command calculation unit 12. As the operation command Run *, “1” is input when the motor drive system 1 is operated, and “0” is input when the motor drive system 1 is stopped. The magnetic flux command calculation unit 12 calculates the magnetic flux command φ * based on the operation command Run * and the motor rotation speed ω1 input from the pseudo-differentiator 11. The magnetic flux command calculation unit 12 outputs the calculated magnetic flux command φ * to the current reference calculation unit 13, the magnetization request generation unit 19, and the variable magnetic flux control unit 21.

  A torque command Tm * is input to the current reference calculation unit 13. The torque command Tm * is a command serving as a reference for torque output from the variable magnetic flux motor 4. The current reference calculation unit 13 is based on the torque command Tm * and the magnetic flux command φ * input from the magnetic flux command calculation unit 12, and serves as a DQ axis current reference IdR and Q axis current that is a reference for the DQ axis current output from the inverter 2. Calculate the reference IqR. The current reference calculation unit 13 outputs the calculated D-axis current reference IdR to the adder AD1. The current reference calculation unit 13 outputs the calculated Q-axis current reference IqR to the voltage command calculation unit 15 as a Q-axis current command Iq * that is a command for controlling the Q-axis current.

  Here, the D axis on the DQ axis is an axis in the direction of magnet magnetic flux (an axis that does not act on the magnetic torque). The Q axis on the DQ axis is an axis (axis acting on the magnetic torque) orthogonal to the axis in the magnetic flux direction (D axis).

  The adder AD1 adds a magnetization correction amount ΔIdm * input from the variable magnetic flux control unit 21, which will be described later, to the D-axis current reference IdR input from the current reference calculation unit 13, and a command for controlling the D-axis current. A D-axis current command Id * is calculated. The adder AD1 outputs the calculated D-axis current command Id * to the voltage command calculation unit 15.

  The coordinate conversion unit 14 receives the rotation angle θ output from the rotation angle sensor 5 and the U-phase current Iu and the W-phase current Iw output from the AC current detectors 8U and 8W. The coordinate conversion unit 14 converts the three-phase AC currents Iu and Iw output from the inverter 2 into DQ-axis currents Id and Iq based on the rotation angle θ, the U-phase current Iu, and the W-phase current Iw. The coordinate conversion unit 14 outputs the calculated D-axis current Id and Q-axis current Iq to the voltage command calculation unit 15 and the current magnetic flux calculation unit 20.

  The voltage command calculation unit 15 includes a D-axis current command Id * input from the current reference calculation unit 13 via the adder AD1, a Q-axis current command Iq * input from the current reference calculation unit 13, and a pseudo-differentiator 11 Based on the input motor rotation speed ω1 and the D-axis current Id and Q-axis current Iq input from the coordinate conversion unit 14, the D-axis voltage is a command for controlling the DQ-axis voltage output from the inverter 2. A command Vd * and a Q-axis voltage command Vq * are calculated. The voltage command calculation unit 15 outputs the calculated D-axis voltage command Vd * and Q-axis voltage command Vq * to the coordinate conversion unit 16. The voltage command calculation unit 15 outputs the calculated Q-axis voltage command Vq * to the current magnetic flux calculation unit 20.

  The rotation angle θ output from the rotation angle sensor 5 is input to the coordinate conversion unit 16. The coordinate conversion unit 16 converts the DQ axis voltage commands Vd * and Vq * input from the voltage command calculation unit 15 into three-phase AC voltage commands Vu *, Vv * and Vw * based on the rotation angle θ. . The coordinate conversion unit 16 outputs the calculated U-phase voltage command Vu *, V-phase voltage command Vv *, and W-phase voltage command Vw * to a PWM (Pulse Width Modulation) circuit 17.

  An operation command Run * is input to the gate command generation unit 15. The gate command generation unit 15 generates a gate command Gst based on the operation command Run *. The gate command generation unit 15 outputs the generated gate command Gst to the PWM circuit 17. When starting to drive the variable magnetic flux motor 4, the gate command generation unit 15 changes the gate command Gst from “0” to “1” in order to start the gate of the inverter 2. When the variable magnetic flux motor 4 is stopped, the gate command generator 15 receives the signal indicating the stop by the operation command Run * and sets the gate command Gst to “1” in order to gate off the inverter 2 after a predetermined time has elapsed. To "0". The reason why the gate is turned off after the lapse of the predetermined time is to reduce the induced voltage during free run and demagnetize the variable magnet and then stop it.

  The PWM circuit 17 controls the drive of the switching element of the inverter 2 by the gate command Gst input from the gate command generation unit 18. The PWM circuit 17 outputs a gate signal for controlling the inverter 2 by pulse width modulation to the inverter 2 based on the voltage commands Vu *, Vv *, Vw * input from the coordinate conversion unit 16.

  An operation command Run * is input to the magnetization request generator 19. The magnetization request generator 19 generates a magnetization request flag FCreq based on the magnetic flux command φ * and the operation command Run * input from the magnetic flux command calculator 12. The magnetization request generator 19 outputs the generated magnetization request flag FCreq to the variable magnetic flux controller 21. The magnetization request flag FCreq is a flag for requesting magnetization for changing the magnet magnetic flux of the variable magnetic flux motor 4. When the magnetization request flag FCreq is set, the control unit 10 performs control to change the magnet magnetic flux of the variable magnetic flux motor 4.

  The current magnetic flux calculation unit 20 includes the motor rotation speed ω1 input from the pseudo-differentiator 11, the DQ axis currents Id and Iq input from the coordinate conversion unit 14, and the Q-axis voltage command Vq input from the voltage command calculation unit 15. Based on *, the current magnet magnetic flux φ of the variable magnetic flux motor 4 is calculated. The current magnetic flux calculation unit 20 outputs the calculated magnet magnetic flux φ to the variable magnetic flux control unit 21.

  The variable magnetic flux controller 21 receives the torque command Tm * and the DC voltage VFC output from the DC voltage detector 7. When the magnetization request flag FCreq is set, the variable magnetic flux control unit 21 starts control for changing the magnet magnetic flux of the variable magnetic flux motor 4. The variable magnetic flux control unit 21 generates a D-axis current based on the torque command Tm *, the DC voltage VFC, the motor rotational speed ω1 input from the pseudo-differentiator 11, and the magnetic flux command φ * input from the magnetic flux command calculation unit 12. A magnetization correction amount ΔIdm * that is a correction amount for correcting the reference IdR is calculated. The variable magnetic flux controller 21 outputs the calculated magnetization correction amount ΔIdm * to the adder AD1. When the D-axis current command Id * is corrected by the magnetization correction amount ΔIdm *, the control unit 10 causes a magnetization current (D-axis current Id) to flow from the inverter 2 to the variable magnetic flux motor 4. The variable magnetic flux motor 4 changes the magnetic flux of the rotor of the variable magnetic flux motor 4 (the total of the respective magnetic fluxes of the fixed magnet and the variable magnet) by changing the magnetic flux of the variable magnet by the magnetizing current.

  Here, various calculation formulas used for calculation in the control unit 10 will be described.

  First, current limitation will be described.

The voltage equation of the variable magnetic flux motor 4 is shown in Formula (1). The torque equation is shown in equation (2).

  Here, “Vd” is the D-axis motor terminal voltage, “Vq” is the Q-axis motor terminal voltage, “Id” is the D-axis motor current, “Iq” is the Q-axis motor current, “R” is the resistance, “Ld” Is the D-axis inductance, “Lq” is the Q-axis inductance, “ω1” is the motor rotation speed, “φ” is the magnetic flux, “p” is d / dt, “τ” is the torque, and “Pn” is the number of pole pairs. Show.

  In the right side of Equation (1), the first term is a voltage drop due to resistance and inductance, the second term is a voltage due to armature reaction, and the third term is a counter electromotive voltage generated from the magnet. The magnitudes of the second and third terms are proportional to the motor rotational speed ω1.

Next, the maximum value of the current flowing through the variable magnetic flux motor 4 is shown in Expression (3).

  As shown in Expression (3), the current limit is a circle having a radius of the motor rated current Imax on the DQ axis coordinate plane.

  Next, voltage limitation will be described.

  The motor terminal voltage is limited by the inverter input voltage. In particular, at the time of high rotation, the second and third terms of the formula (1) are dominant in the motor terminal voltage.

A formula representing the voltage limiting characteristic is shown in Formula (4).

  Here, “VFC” indicates an inverter input voltage.

  As shown in Expression (4), the voltage limiting characteristic is elliptical. The limit value is a ratio (V / ω limit) between the inverter terminal voltage and the motor rotation speed. That is, the higher the motor rotation speed or the lower the DC voltage VFC, the smaller the V / ω limit value and the less the motor current flows.

From Expression (1), an expression for obtaining the current magnet magnetic flux φ in the current magnetic flux calculation unit 20 is obtained as Expression (5).

  FIG. 2 is a block diagram illustrating a configuration of a magnetization current calculation unit 21P that calculates the magnetization correction amount ΔIdm * of the variable magnetic flux control unit 21 according to the present embodiment.

  The magnetization current calculation unit 21P includes an adjustment gain 211, a magnetization current calculation table 212, a subtractor SU21, and an adder AD21.

  In the magnetizing current calculation table 212, a magnetizing current table designed by the nominal value VN of the inverter input voltage is set as an initial state.

  The subtractor SU21 calculates the difference between the DC voltage VFC detected by the DC voltage detector 7 and the nominal value VN. The subtractor SU21 outputs the calculated difference to the adjustment gain 211.

  The adjustment gain 211 calculates a rotational speed correction amount by multiplying the difference calculated by the subtractor SU21 by a preset gain. The adjustment gain 211 outputs the calculated rotation speed correction amount to the adder AD21.

  The adder AD21 adds the rotational speed correction amount input from the adjustment gain 211 to the motor rotational speed ω1 input from the pseudo-differentiator 11. The adder AD21 outputs the motor rotation speed ω1 obtained by adding the rotation speed correction amount to the magnetization current calculation table 212.

  The magnetizing current calculation table 212 corrects the magnetizing current table designed by the nominal value VN of the inverter input voltage based on the value input from the adder AD21.

  The magnetization current calculation table 212 calculates the magnetization correction amount ΔIdm * based on the current magnet flux φ so as to maintain the torque command Tm * using the corrected magnetization current table. The magnetization current calculation table 212 outputs the calculated magnetization correction amount ΔIdm * to the adder AD1.

  FIG. 3 is a coordinate diagram showing a magnetizing current table according to the present embodiment.

  The magnetization current table is a coordinate indicating the amount of magnetic flux required when the horizontal axis is the rotation speed and the vertical axis is the torque. This coordinate is divided into N areas D1 to DN. Each area | region D1-DN has shown the magnetic flux amount required in order to output a torque. In the magnetization current table, the scale of the rotation speed (width of the horizontal axis) is corrected by the value input from the adder AD21. Thereby, the magnetizing current table is corrected so as to correspond to the varying DC voltage VFC.

  The amount of magnetic flux required for the variable magnetic flux motor 4 is determined depending on which region D1 to DN the torque command Tm * belongs to. The magnetization current calculation table 212 calculates the magnetization correction amount ΔIdm * based on the necessary magnetic flux amount determined by the magnetization current table and the current magnet magnetic flux φ.

  With reference to FIGS. 4 to 6, control by the magnetizing current table according to the present embodiment will be described.

  FIG. 4 is a coordinate diagram showing the relationship between the torque and the DC voltage VFC of the motor drive system 1 according to the present embodiment. The horizontal axis indicates the D-axis current (magnetization current) Id. The vertical axis represents the Q-axis current Iq. This coordinate represents a case where the motor rotation speed ω1 is 1000 [rad / sec].

  The current limit graph IR shows a case where the current limit is 333 [A].

  The V / ω limit graph FR41 indicates the V / ω limit when the DC voltage VFC is 400 [V]. The V / ω limit graph FR42 indicates the V / ω limit when the DC voltage VFC is 200 [V]. The graph FR43 shows the V / ω limit when the DC voltage VFC is 100 [V].

  A torque curve FT41 shows a case where the torque is 100 [Nm]. A torque curve FT42 shows a case where the torque is 60 [Nm]. A torque curve FT43 shows a case where the torque is 30 [Nm].

  As shown in the V / ω limit graphs FR41 to FR43, the lower the DC voltage VFC, the smaller the V / ω limit.

  The operating point where the maximum torque is generated is the point where the circle of the current limit graph IR and the ellipse of the V / ω limit graphs FR41 to FR43 overlap.

  Since it is calculated from torque curves FT41 to FT43 and equation (2), it becomes a hyperbola.

  As an example, a case where the DC voltage VFC is reduced from 200 [V] to 100 [V] will be described.

  When the DC voltage VFC is 200 [V], the DQ axis currents Id and Iq when the maximum torque is generated are the intersections of the V / ω limit graph FR42 and the current limit graph IR. The maximum torque at this time is a torque curve passing through this intersection. Therefore, the torque 60 [Nm] of the torque curve FT42 passing through this intersection is the maximum torque.

  Similarly, when the DC voltage VFC is 100 [V], the torque curve passing through the intersection of the V / ω limit graph FR43 and the current limit graph IR becomes the maximum torque. Therefore, the torque 30 [Nm] of the torque curve FT43 passing through this intersection is the maximum torque.

  Therefore, when the motor rotational speed ω1 is 1000 [rad / sec] and the DC voltage VFC decreases from 200 [V] to 100 [V], the maximum torque decreases from 60 [Nm] to 30 [Nm]. To do.

  Next, a case where the magnetic flux φ decreases will be described.

  FIG. 5 is a coordinate diagram showing the relationship between the magnetic flux φ and the torque of the motor drive system 1 according to the present embodiment. The horizontal axis indicates the D-axis current (magnetization current) Id. The vertical axis represents the Q-axis current Iq. These coordinates represent a case where the motor rotation speed ω1 is 1000 [rad / sec] and the DC voltage VFC is 100 [V].

  The current limit graph IR shows a case where the current limit is 333 [A].

  The V / ω limit graph FR51 shows the V / ω limit when the magnetic flux φ is 0.157 [Wb]. The V / ω limit graph FR52 shows the V / ω limit when the magnetic flux φ is 0.125 [Wb]. The V / ω limit graph FR53 shows the V / ω limit when the magnetic flux φ is 0.094 [Wb].

  A torque curve FT51 shows a case where the torque is 31 [Nm] and the magnetic flux φ is 0.094 [Wb]. A torque curve FT52 shows a case where the torque is 33 [Nm] and the magnetic flux φ is 0.125 [Wb]. A torque curve FT53 shows a case where the torque is 30 [Nm] and the magnetic flux φ is 0.157 [Wb].

  As the magnetic flux φ decreases, as shown in FIG. 5, the center point of the V / ω-restricted ellipse (V / ω-restricted graphs FR51 to FR53) is closer to the origin. As a result, the intersection of the V / ω limit ellipse and the current limit circle (current limit graph IR) moves.

  When the magnetic flux φ decreases from 0.157 [Wb] (V / ω limit graph FR51) to 0.125 [Wb] (V / ω limit graph FR52), the V / ω limit ellipse (V / ω limit graph FR51, FR52) and the intersection of the current limit circle (current limit graph IR) move in the direction in which the Q-axis current Iq increases. Therefore, the torque increases.

  On the other hand, when the magnetic flux φ decreases from 0.125 [Wb] (V / ω limit graph FR52) to 0.094 [Wb] (V / ω limit graph FR53), the V / ω limit ellipse (V / ω limit graph). FR52, FR53) and the intersection of the current limiting circle (current limiting graph IR) move in the direction in which the Q-axis current Iq increases. However, since the magnetic flux φ itself decreases, the torque decreases. Therefore, if the magnetic flux φ is reduced too much, the torque decreases.

  Next, the principle of controlling to maintain torque against fluctuations in the DC voltage VFC using a magnetizing current table will be described.

  FIG. 6 is a coordinate diagram for explaining the principle of control by the magnetizing current table of the motor drive system 1 according to the present embodiment. The horizontal axis indicates the D-axis current (magnetization current) Id. The vertical axis represents the Q-axis current Iq. This coordinate represents a case where the motor rotation speed ω1 is 1000 [rad / sec].

  The current limit graph IR shows a case where the current limit is 333 [A].

  The initial state of the motor drive system 1 is assumed that the DC voltage VFC is 100 [V] and the magnetic flux φ is 0.157 [Wb]. At this time, the V / ω limit is the V / ω limit graph FR61. Further, the torque curve FT61 is obtained from the intersection of the current limit graph IR and the V / ω limit graph FR61. Therefore, at this time, the torque is 31 [Nm].

  Next, it is assumed that the DC voltage VFC changes from 100 [V] to 90 [V]. At this time, the V / ω limit is the V / ω limit graph FR62. Therefore, the torque decreases to 26 [Nm] (torque curve FT62).

  Here, when the magnetizing current Id is passed and the magnetic flux φ is demagnetized from 0.157 [Wb] to 0.110 [Wb], the V / ω limit becomes the V / ω limit graph FR63. Therefore, the torque recovers to 30 [Nm] (torque curve FT63).

  Therefore, the magnetizing current table is created using the nominal value of the inverter input voltage (DC voltage VFC) so that the above-described control can be performed. The variable magnetic flux control unit 21 makes corrections based on the detected value of the DC voltage VFC or the motor rotational speed ω1 based on this magnetization current table. As a result, the magnetizing current table becomes versatile enough to cope with fluctuations in the DC voltage VFC and the motor rotational speed ω1.

  According to this embodiment, the variable magnetic flux control unit 21 can change the magnetic flux of the variable magnetic flux motor 4 so as to maintain the torque based on the DC voltage VFC detected by the DC voltage detector 7. Thereby, the motor drive system 1 can operate with high robustness against fluctuations in the DC voltage VFC input to the inverter 2.

(Second Embodiment)
FIG. 7 is a block diagram showing the configuration of a motor drive system 1A according to the second embodiment of the present invention.

  The motor drive system 1A is the same as the motor drive system 1 according to the first embodiment shown in FIG. 1, except that the control unit 10 is replaced with the control unit 10A, the variable magnetic flux motor 4 is replaced with the variable magnetic flux motor 4A, the slip ring 6 and the magnetization A circuit 50 and an alternating current detector 8M are added. Other points are the same as those of the motor drive system 1.

  In the variable magnetic flux motor 4 according to the first embodiment, the variable magnetic flux motor 4A is provided with a magnetized winding on the rotor. The other points are the same as those of the variable magnetic flux motor 4. The magnetizing winding is a winding for changing the magnetic flux of the variable magnet provided in the rotor of the variable magnetic flux motor 4 by passing a magnetizing current.

  The magnetizing circuit 50 is connected via a slip ring 6 to the magnetizing winding of the rotor of the variable magnetic flux motor 4A. The magnetizing circuit 50 causes a magnetizing current to flow through the magnetizing winding based on the magnetizing current command ImagRef received from the control unit 10A.

  The magnetization circuit 50 includes a magnetization winding control unit 51, a magnetization converter 53, and a DC power supply 54.

  The DC power supply 54 supplies DC power to the magnetization converter 53.

  The magnetization converter 53 converts the DC power supplied from the DC power supply 54 and causes the magnetization current Imag to flow through the magnetization winding via the slip ring 6.

  The alternating current detector 8M detects the magnetization current Imag flowing from the magnetization converter 53 to the magnetization winding. The AC current detector 8M outputs the detected magnetization current Imag to the magnetization winding control unit 51.

  The magnetization winding control unit 51 controls the magnetization converter 53 based on the magnetization current command ImagRef received from the variable magnetic flux control unit 21A of the control unit 10A. The magnetization winding control unit 51 includes a magnetization current control unit 52. The magnetizing current control unit 52 performs PI (proportional-plus-integral control) control so that the magnetizing current Imag detected by the AC current detector 8M matches the magnetizing current command ImagRef. The magnetizing current control unit 52 may be controlled by a hysteresis comparator or the like instead of the PI control.

  FIG. 8 is a block diagram showing a configuration of the magnetization current calculation unit 21PA of the variable magnetic flux control unit 21A according to the present embodiment.

  In the control unit 10 according to the first embodiment, the control unit 10A replaces the magnetization current calculation table 212 of the magnetization current calculation unit 21P of the variable magnetic flux control unit 21 with a magnetization current calculation table 212A. Other points are the same as those of the control unit 10.

  The magnetization current calculation table 212A calculates the magnetization current command ImagRef together with the magnetization correction amount ΔIdm *. The magnetization current calculation table 212A transmits the calculated magnetization current command ImagRef to the magnetization circuit 50. As a result, the magnetization circuit 50 causes the magnetization current Imag to flow through the magnetization winding.

  According to the present embodiment, in addition to the operational effects of the first embodiment, the following operational effects can be obtained.

  By providing a dedicated magnetization circuit 50 for magnetizing the magnetization winding, the current capacity of the inverter 2 can be reduced. Thereby, the inverter 2 can be reduced in size or weight.

  Further, since the magnetizing circuit 50 is provided exclusively for magnetizing, the magnetizing circuit 50 can have an optimum configuration for magnetizing. Further, the control of the magnetizing circuit 50 can always apply an arbitrary voltage and flow the magnetizing current Imag without depending on the output of the inverter 2. Accordingly, the magnetization circuit 50 can efficiently magnetize the magnetization winding. That is, the magnetization circuit 50 can efficiently change the magnetic flux of the variable magnetic flux motor 4.

  Furthermore, since the magnetizing winding is provided on the rotor of the variable magnetic flux motor 4A, the magnetizing converter 53 is magnetized from the stator side because it is not easily affected by magnetic saturation even when the variable magnet is magnetized. Compared to the case, the variable magnet can be efficiently magnetized with a smaller magnetization current Imag. Even when the magnetic flux is changed, the variable magnetic flux motor 4A can minimize the generation of transient torque. Moreover, when it has saliency, the magnetizing current Imag that flows through the magnetizing winding does not directly become a reluctance torque, so that torque fluctuation can be suppressed.

(Third embodiment)
FIG. 9 is a block diagram showing a configuration of a motor drive system 1B according to the third embodiment of the present invention.

  In the motor drive system 1B according to the first embodiment shown in FIG. 1, the control unit 10 is replaced with a control unit 10B. Other points are the same as those of the motor drive system 1.

  In the control unit 10 according to the first embodiment, the control unit 10B includes a magnetic flux command calculation unit 12B instead of the magnetic flux command calculation unit 12, and a variable magnetic flux control unit 21B instead of the variable magnetic flux control unit 21. .

  FIG. 10 is a block diagram illustrating a configuration of the magnetic flux command calculation unit 12B and the variable magnetic flux control unit 21B according to the present embodiment.

  The DC command VFC detected by the DC voltage detector 7, the motor rotational speed ω1 calculated by the pseudo-differentiator 11, and the torque command Tm * are input to the magnetic flux command calculator 12B. The magnetic flux command calculation unit 12B calculates a magnetic flux command φ * based on the DC voltage VFC, the motor rotation speed ω1, and the torque command Tm *.

From Equation (2), Equation (3), and Equation (4), the magnetic flux (φ) is the torque (τ), motor rotation speed (ω1), and DC voltage (VFC) as shown in Equation (6). It becomes a function by.

  The magnetic flux command calculation unit 12B calculates the magnetic flux command φ * using Expression (6). The magnetic flux command calculation unit 12B outputs the calculated magnetic flux command φ * to the variable magnetic flux control unit 21B.

  The variable magnetic flux control unit 21B calculates the magnetization correction amount ΔIdm * based on the magnetic flux command φ * input from the magnetic flux command calculation unit 12B and the current magnet magnetic flux φ input from the current magnetic flux calculation unit 20. The variable magnetic flux controller 21B outputs the calculated magnetization correction amount ΔIdm * to the adder AD1.

  The variable magnetic flux control unit 21B includes subtracters SU91 and SU92 and a magnetizing current command calculation unit 21BP1. In the variable magnetic flux control unit 21B, a magnet magnetic flux φ1 of a fixed magnet is set.

  The subtractor SU91 calculates a difference between the magnetic flux command φ * and the magnet magnetic flux φ1 of the fixed magnet. This difference becomes a magnetic flux command φ2 * which is a command for controlling the variable magnet. The subtractor SU91 outputs the calculated magnetic flux command φ2 * to the magnetizing current command calculating unit 21BP1.

  The subtractor SU92 calculates the difference between the current magnet flux φ and the magnet flux φ1 of the fixed magnet. This difference is the current magnet flux φ2 of the variable magnet. The subtractor SU92 outputs the calculated magnet magnetic flux φ2 to the magnetization current command calculation unit 21BP1.

  The magnetization current command calculation unit 21BP1 calculates the magnetization correction amount ΔIdm * based on the magnetic flux command φ2 * and the current magnet magnetic flux φ2. The magnetization current command calculation unit 21BP1 outputs the calculated magnetization correction amount ΔIdm * to the adder AD1.

  FIG. 11 is a characteristic diagram showing magnetization characteristics FB (magnetic flux density-magnetization characteristics) of the variable magnet according to the present embodiment. The horizontal axis indicates the magnetization current Id (D-axis current). The vertical axis represents the magnetic flux.

  The magnetization current command calculation unit 21BP1 calculates the magnetization correction amount ΔIdm * using the characteristic diagram of the variable magnet shown in FIG.

  A case where the magnetic flux φA is changed to the magnetic flux φB will be described with reference to FIG.

  Since the magnetic flux φA is larger than the magnetic flux φB, a magnetization current flows in the direction of demagnetizing the variable magnet.

  Therefore, the intersection of the negative direction of the horizontal axis (magnetization current axis) and the magnetization characteristic FB is calculated from the magnetic flux φB. The length of the intersection in the horizontal axis direction is the magnetization current Id1 necessary for changing the magnetic flux φB.

  The magnetization current command calculation unit 21BP1 calculates the magnetization correction amount ΔIdm * based on the calculated magnetization current Id1.

  On the other hand, when the magnetization is increased, the magnetization current command calculation unit 21BP1 calculates the magnetization current Id2 by calculating the intersection point between the positive direction of the magnetization current and the magnetization characteristic FB.

  According to the present embodiment, by calculating the magnetic flux command φ * based on the DC voltage VFC detected by the DC voltage detector 7, the motor drive system 1 B can change the DC voltage VFC input to the inverter 2. On the other hand, it is possible to drive with high robustness.

  Further, by calculating the magnetic flux command φ * based on the torque command Tm *, the motor drive system 1B can change the magnetic flux φ of the variable magnetic flux motor 4 so that torque according to the torque command Tm * can be output. it can.

(Fourth embodiment)
FIG. 12 is a block diagram showing configurations of the magnetic flux command calculation unit 12B and the variable magnetic flux control unit 21B2 according to the fourth embodiment of the present invention. FIG. 13 is a characteristic diagram showing the magnetization characteristics of the variable magnet for calculating the magnetization correction amount ΔIdm * in the magnetization current command calculation unit 21BP2 according to the present embodiment.

  The variable magnetic flux control unit 21B2 has a configuration in which a magnetization current command calculation unit 21BP2 is provided instead of the magnetization current command calculation unit 21BP1 in the variable magnetic flux control unit 21B according to the third embodiment shown in FIG. In other respects, the motor drive system according to the present embodiment is the same as the motor drive system 1B according to the third embodiment.

  Next, a calculation method of the magnetization correction amount ΔIdm * in the magnetization current command calculation unit 21BP2 will be described.

  As an example, as shown in FIG. 13, a case where the inside of the magnetization characteristic FB is divided into a plurality of regions D1 to D5 will be described. A hysteresis region is provided between the regions D1 to D5. In the magnetization current command calculation unit 21BP1, magnetization currents Id (or magnetization correction amounts ΔIdm *) corresponding to the regions D1 to D5 are determined in advance. The magnetization current Id is determined in advance for each of the case where the magnetization is increased and the case where the magnetization is decreased.

  The magnetizing current command calculation unit 21BP1 does not magnetize the variable magnet when the input magnetic flux command φ2 * is in the same region D1 to D5 as the current magnet magnetic flux φ2 of the variable magnet. That is, the magnetization current command calculation unit 21BP1 does not output the magnetization correction amount ΔIdm *.

  When the input magnetic flux command φ2 * is in a region D1 to D5 different from the current magnet magnetic flux φ2 of the variable magnet, the magnetization current command calculation unit 21BP1 corresponds to the region D1 to D5 to which the magnetic flux command φ2 * belongs. The magnetization correction amount ΔIdm * of the magnetization current is output to the adder AD1.

  According to the present embodiment, in addition to the functions and effects of the third embodiment, the following functions and effects can be obtained.

  In the calculation method by the magnetization current command calculation unit 21BP2, the magnetization characteristics of the variable magnet are divided into a plurality of regions D1 to D5. In each of the regions D1 to D5, a representative magnetization current Id is determined in advance. Thereby, the frequency | count of flowing the magnetizing current Id can be reduced. Therefore, by controlling by the magnetization current command calculation unit 21BP2, the variable magnetic flux control unit 21B2 prevents the loss due to the frequent flow of the magnetization current Id, and changes in the magnetic flux φ of the variable magnetic flux motor 4 Can be controlled. The plurality of regions may be two or more.

(Fifth embodiment)
FIG. 14 is a block diagram showing a configuration of a motor drive system 1C according to the fifth embodiment of the present invention. FIG. 15 is a block diagram illustrating the configuration of the magnetic flux command calculation unit 12B and the variable magnetic flux control unit 21C according to the present embodiment.

  The motor drive system 1C is the same as the motor drive system 1B according to the third embodiment shown in FIG. 9, except that the control unit 10B is replaced with the control unit 10C, the variable magnetic flux motor 4 is replaced with the variable magnetic flux motor 4A, the slip ring 6 and the magnetization A circuit 50 and an alternating current detector 8M are added. Other points are the same as those of the motor drive system 1B.

  Since the variable magnetic flux motor 4A, the slip ring 6, the magnetization circuit 50, and the AC current detector 8M have the same device configuration as that of the second embodiment shown in FIG.

  The controller 10C includes a variable magnetic flux controller 21C instead of the variable magnetic flux controller 21B in the controller 10B according to the third embodiment.

  The variable magnetic flux control unit 21C has a configuration in which a magnetization current command calculation unit 21BPC is provided instead of the magnetization current command calculation unit 21BP1 in the variable magnetic flux control unit 21B according to the third embodiment shown in FIG.

  The magnetization current command calculation unit 21BPC calculates the magnetization current command ImagRef together with the magnetization correction amount ΔIdm *. The magnetizing current command calculating unit 21BPC transmits the calculated magnetizing current command ImagRef to the magnetizing circuit 50. As a result, the magnetization circuit 50 causes the magnetization current Imag to flow through the magnetization winding.

  According to the present embodiment, with the motor drive system 1B according to the third embodiment as a basic configuration, the device configuration related to the magnetizing circuit 50 according to the second embodiment is added, and thereby the operational effects of the third embodiment. In addition, the operational effects of the second embodiment can be obtained.

  In each embodiment, the rotation angle sensor is provided to measure the motor rotation speed of the variable magnetic flux motor 4, but the present invention is not limited to this. The motor rotation speed of the variable magnetic flux motor 4 may be estimated based on the detected current value by detecting the output current of the inverter 4.

  In the fifth embodiment, the motor drive system 1B according to the third embodiment has a basic configuration, but the motor drive system according to the fourth embodiment may have a basic configuration.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 1 ... Motor drive system, 2 ... Inverter, 3 ... DC power supply, 4 ... Variable magnetic flux motor, 5 ... Rotation angle sensor, 7 ... DC voltage detector, 8U, 8W ... AC current detector, 10 ... Control part, 11 ... Pseudo-differentiator, 12 ... Magnetic flux command calculation unit, 13 ... Current reference calculation unit, 14 ... Coordinate conversion unit, 15 ... Voltage command calculation unit, 16 ... Coordinate conversion unit, 17 ... PWM circuit, 18 ... Gate command generation unit, 19 ... Magnetization request generation unit, 20 ... Current magnetic flux calculation unit, 21 ... Variable magnetic flux control unit, AD1 ... Adder.

Claims (6)

DC power supply,
A permanent magnet synchronous motor having a permanent magnet Ru changing the magnetic flux,
An inverter that converts the DC power supplied from the DC power source into AC power and drives the permanent magnet synchronous motor;
Magnetic flux variable means for calculating a magnetizing current command value for outputting a magnetizing current for changing the magnetic flux of the permanent magnet from the inverter to the permanent magnet synchronous motor;
DC voltage detection means for detecting a DC voltage input to the inverter;
Magnetic flux estimating means for estimating the magnetic flux of the permanent magnet;
Rotational speed calculation means for calculating the rotational speed of the permanent magnet synchronous motor;
A variable magnetic flux control means for calculating a magnetization correction amount, correcting the magnetization current command value with the magnetization correction amount, and performing control to change the magnetic flux of the permanent magnet ;
The variable magnetic flux control means is a command for correcting the rotation speed calculated by the rotation speed calculation means and controlling the torque of the permanent magnet synchronous motor based on the DC voltage detected by the DC voltage detection means. Calculating the magnetization correction amount based on a torque command, the rotation speed corrected by the rotation speed correction means, and the magnetic flux estimated by the magnetic flux estimation means;
Motor drive system according to claim. The variable magnetic flux control means changes the magnetic flux of the permanent magnet so as to maintain the torque of the permanent magnet synchronous motor.
Motor drive system of claim 1, wherein the. The permanent magnet synchronous motor is wound with a magnetizing winding that changes the magnetic flux of the permanent magnet around the rotor,
Magnetizing current output means for a magnetizing winding is provided which passes a magnetizing current that changes the magnetic flux of the permanent magnet to the magnetizing winding.
Motor drive system as claimed in claim 1 or claim 2, characterized in. An inverter control device that controls an inverter that drives a permanent magnet synchronous motor including a permanent magnet that changes magnetic flux and converts DC power into AC power,
Magnetic flux variable means for calculating a magnetizing current command value for outputting a magnetizing current for changing the magnetic flux of the permanent magnet from the inverter to the permanent magnet synchronous motor;
DC voltage detection means for detecting a DC voltage input to the inverter;
Magnetic flux estimating means for estimating the magnetic flux of the permanent magnet;
Rotational speed calculation means for calculating the rotational speed of the permanent magnet synchronous motor;
A variable magnetic flux control means for calculating a magnetization correction amount, correcting the magnetization current command value with the magnetization correction amount, and performing control to change the magnetic flux of the permanent magnet;
The variable magnetic flux control means is a command for correcting the rotation speed calculated by the rotation speed calculation means and controlling the torque of the permanent magnet synchronous motor based on the DC voltage detected by the DC voltage detection means. The inverter control device characterized in that the magnetization correction amount is calculated based on a torque command, the rotation speed corrected by the rotation speed correction means, and the magnetic flux estimated by the magnetic flux estimation means. . The inverter control device according to claim 4 , wherein the variable magnetic flux control means changes the magnetic flux of the permanent magnet so as to maintain the torque of the permanent magnet synchronous motor . The permanent magnet synchronous motor, magnetization windings Ru changing the magnetic flux of the permanent magnet in the rotor is wound,
Inverter control device according to claim 4 or claim 5, characterized in that with a magnetizing current output means for magnetizing winding supplying a magnetization current Ru changing the magnetic flux of the permanent magnet in the magnetization winding.

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