Motor control device

Abstract

To provide a motor control device that can standardize the speed controller between a normal control mode and a flux-weakening control mode, improving stability and making design easier.SOLUTION: A motor control device includes a motor drive control unit, a conversion unit, a speed controller, a first voltage command value generator, a torque command value generator, a second voltage command value generator, and a control switching processing unit. The motor drive control unit performs control in a normal control mode and a flux-weakening control mode. The conversion unit converts the motor current into a q-axis current and a d-axis current. The speed controller generates a current command value. The first voltage command value generator generates a first voltage command value. The torque command value generator generates a torque command value for the motor. The second voltage command value generator generates a second voltage command value. The control switching processing unit outputs the first voltage command value to the motor drive control unit when the normal control mode is selected, and outputs the second voltage command value to the motor drive control unit when the flux-weakening control mode is selected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor control device. [Background technology]

[0002] Among motor control devices, there are those that perform vector control of the motor by decomposing the motor current flowing through the motor into d-axis current and q-axis current.During normal operation, the motor control device performs energy-saving operation mainly using maximum torque / current control (normal control mode), and when the voltage amplitude reaches the output limit during high output, it switches to flux-weakening control (flux-weakening control mode) to further increase the rotation speed.

[0003] Patent Document 1 describes a motor control device that can achieve non-interference between the d-axis voltage command value and the q-axis voltage command value when switching between a normal control mode and a flux-weakening control mode that corresponds to saturation of the voltage applied to the motor. Patent Document 2 describes a control device for a synchronous motor that switches between a normal control mode and a flux-weakening control mode. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6115250 [Patent Document 2] Patent No. 5870591 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the speed controller is switched to the q-axis side in the normal control mode and to the d-axis side in the flux-weakening control mode. Therefore, the gain of the speed controller changes before and after the switching, and the speed controller cannot be shared between the normal control mode and the flux-weakening control mode.

[0006] In addition, in Patent Document 2, either the d-axis current calculation value for field-weakening control (flux-weakening control mode) or the d-axis current set value for maximum torque control (normal control mode) is output as the d-axis current command value based on the maximum line voltage and the electrical angular speed of the synchronous motor. However, in Patent Document 2, the speed controller that generates the command current value must be switched, and the speed controller cannot be shared between the normal control mode and the flux-weakening control mode.

[0007] The present invention has been made with a focus on the previously unresolved problems, and aims to provide a motor control device that can use a common speed controller for both normal control mode and flux-weakening control mode, thereby improving stability and making design easier. [Means for solving the problem]

[0008] In order to achieve the above object, according to one aspect of the present invention, there is provided a motor drive control unit that controls the drive of a motor in either a normal control mode or a flux-weakening control mode corresponding to saturation of a voltage applied to the motor in response to an input voltage command value, a conversion unit that converts a motor current flowing through the motor into a q-axis current and a d-axis current, a speed controller that generates a current command value based on a speed difference between a command angular velocity for the motor and an actual angular velocity of the motor, and a first voltage command converter that generates a first voltage command value based on the difference between the current command value and each of the q-axis current and the d-axis current. There is provided a motor control device comprising: a current command value generator; a torque command value generator that generates a torque command value for the motor from a current command value; a second voltage command value generator that generates a second voltage command value based on a difference between the torque command value and an actual torque of the motor; and a control switching processor that switches between a normal control mode and a flux-weakening control mode based on the current command value, wherein the control switching processor outputs a first voltage command value to the motor drive controller when the normal control mode is selected, and outputs the second voltage command value to the motor drive controller when the flux-weakening control mode is selected. Effect of the Invention

[0009] According to one aspect of the present invention, a speed controller can be used in common for both the normal control mode and the flux-weakening control mode, thereby improving stability and providing a motor control device that is easier to design. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a configuration of a motor control device according to a first embodiment. [Figure 2A] FIG. 4 is a diagram showing an example of a maximum torque / current control curve. [Figure 2B] FIG. 2 is a diagram showing voltage vectors in the dq plane. [Diagram 3] 1 is a block diagram showing a configuration of a motor control device in a maximum torque / current control mode according to a first embodiment. [Figure 4] 1 is a block diagram showing a configuration of a motor control device in a flux-weakening control mode according to a first embodiment. [Figure 5A] FIG. 13 is a diagram for explaining the operation at the time of switching, focusing on a current transition. [Figure 5B] FIG. 13 is an explanatory diagram showing a voltage transition. [Figure 6] FIG. 2 is a block diagram showing internal models of a speed controller, a d-axis current controller, a q-axis current controller, and a phase angle controller. [Figure 7] 10 is a flowchart showing a control process procedure in a mode transition from a flux-weakening control mode to a maximum torque / current control mode by a control switching processing unit. [Figure 8] 8 is a flowchart showing details of the flux-weakening process shown in FIG. 7. [Figure 9] 8 is a flowchart showing the details of a voltage amplitude reducing process shown in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. The embodiments described below are merely examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the structure, arrangement, etc. of the components to those described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims.

[0012] 1 is a block diagram showing the configuration of a motor control device 1 according to a first embodiment. In the coordinate axes used in the following description, the d-axis is the rotor magnetic flux axis (the N pole side is the + direction), the q-axis is an axis perpendicular to the d-axis, θe is the rotor phase angle expressed in electrical angle, and ωe is the electrical angular velocity of the dq axes.

[0013] The motor control device 1 performs vector control of the synchronous motor M by decomposing the motor current flowing through the synchronous motor M into a q-axis current and a d-axis current. The motor control device 1 controls the rotation speed of the motor M by varying the voltage applied to the motor M (the output voltage of the inverter). The region in which the voltage applied to the motor M is variably controlled is sometimes called the normal control region. In the normal control region, for example, maximum torque / current control (MTPA control) is performed. The synchronous motor M is, for example, a motor with a salient pole ratio greater than 1. In the synchronous motor M, as the rotation speed increases, the back electromotive force due to the power generation action increases, making it difficult to increase the rotation speed any further (i.e., the output voltage of the inverter becomes saturated, and the voltage applied to the synchronous motor M cannot be increased).

[0014] On the other hand, if flux-weakening control could be performed to weaken the magnetic flux in the synchronous motor M, the back electromotive force could be suppressed and the rotation speed could be further increased. For this reason, the motor control device 1 has, for example, a maximum torque / current control mode (one example of a normal control mode) and a flux-weakening control mode as control modes, and is configured to switch from the maximum torque / current control mode to the flux-weakening control mode in response to, for example, the inverter output voltage approaching a saturated state, and to switch from the flux-weakening control mode to the maximum torque / current control mode in response to, for example, the voltage saturation state being released.

[0015] That is, the flux-weakening control mode is a mode corresponding to saturation of the voltage applied to the synchronous motor M. For example, switching from the maximum torque / current control mode to the flux-weakening control mode may be performed when the voltage applied to the synchronous motor M is saturated, or may be performed before the voltage applied to the synchronous motor M is saturated (when it is detected that the magnitude of the inverter output voltage is close to the maximum value).

[0016] The motor control device 1 includes a drive unit 10 (an example of a motor drive control unit), a three-phase / two-phase conversion unit 20 (an example of a conversion unit), a calculator 31, a speed controller 32, a first voltage command value generation unit 40 (an example of a first voltage command value generator), a command torque calculation unit 50 (an example of a torque command value generator), a second voltage command value generation unit 60 (an example of a second voltage command value generator), a control switching processing unit 70, a first switch 81, and a second switch 82.

[0017] The drive unit 10 includes a two-phase / three-phase conversion unit 11, a power conversion unit 12, a converter 13, and an integrator 14. The converter 13 converts a mechanical angular velocity ωm (hereinafter also referred to as mechanical angular velocity) of the rotor in the synchronous motor M into an angular velocity ωe (hereinafter also referred to as electrical angular velocity) of the rotor expressed in electrical angle with the U-phase of a fixed coordinate system (UVW coordinate system) as the origin. That is, the converter 13 obtains the angular velocity ωe by multiplying the angular velocity ωm by the number of pole pairs Pn (Pn is the number of pole pairs of the motor). The converter 13 outputs the obtained angular velocity ωe to the integrator 14 and the calculator 31.

[0018] The integrator 14 integrates the angular velocity ωe of the rotor expressed in electrical angle to obtain the phase angle θe of the rotor expressed in electrical angle with the U-phase of the fixed coordinate system (UVW coordinate system) as the origin. The integrator 14 outputs the phase angle θe to the two-phase / three-phase conversion unit 11 and the three-phase / two-phase conversion unit 20.

[0019] The two-phase / three-phase conversion unit 11 receives a q-axis voltage command value and a d-axis voltage command value. The two-phase / three-phase conversion unit 11 also receives a phase angle θe from an integrator 14. For example, the two-phase / three-phase conversion unit 11 converts a voltage command vector in a rotating coordinate system (dq coordinate system) into a voltage command vector (v u ,v v ,v w ) and convert it into a voltage command vector (v u ,v v ,v w ) to the power conversion unit 12.

[0020] The power conversion unit 12 converts a DC voltage V dc According to this, the U-phase voltage command value v u , V-phase voltage command value v v , W-phase voltage command value v w The power conversion operation is performed by converting the input voltage V, V, and W into a PWM signal, and switching operations of multiple switching elements (not shown) are performed at predetermined timing in accordance with the PWM signal. The generated three-phase AC signals U, V, and W are supplied to a synchronous motor M to drive the synchronous motor M.

[0021] Further, the drive unit 10 includes, for example, a first current sensor 151 and a second current sensor 152. The first current sensor 151 detects a U-phase current i u The second current sensor 152 detects the amplitude of the W-phase current i w The amplitude of the V-phase current i is detected and output to the three-phase / two-phase conversion unit 20. The three-phase / two-phase conversion unit 20 converts the V-phase current i v Calculate.

[0022] The three-phase / two-phase conversion unit 20 converts, for example, a current vector (i u ,i v ,i w ) in the rotating coordinate system (dq coordinate system) as the current vector (i d ,i q) The rotating coordinate system (dq coordinate system) has a d-axis and a q-axis that intersect with each other. Note that the current vector (i d ,i q ) are the components of the detected current vector (i u ,i v ,i w ) is converted from the d-axis current detection value i d , q-axis current detection value i q The three-phase / two-phase conversion unit 20 converts the d-axis current detection value i d and q-axis current detection value i q to the first voltage command value generating unit 40 and the second voltage command value generating unit 60.

[0023] The calculator 31 receives a command angular velocity ωe * and the angular velocity ωe output from the converter 13. The calculator 31 calculates the command angular velocity ωe * and the angular velocity ωe, and outputs the speed difference value Δωe to the speed controller 32. The speed controller 32 calculates the q-axis current command value i q * and d-axis current command value i d * and the q-axis current command value i q * and d-axis current command value i d * to the first voltage command value generating unit 40, the command torque calculating unit 50 and the control switching processing unit .

[0024] The first voltage command value generating unit 40 includes a q-axis current calculator 411, a d-axis current calculator 412, a q-axis current controller 421, a d-axis current controller 422, an adder 431, and an adder 432. The q-axis current calculator 411 receives a q-axis current command value i q * and q-axis current detection value i q The q-axis current calculator 411 receives the q-axis current command value i q * and the q-axis current detection value i q Calculate the difference between qto the q-axis current controller 421. The q-axis current controller 421 outputs the difference value Δi q Based on the voltage v q ' is calculated. Voltage v q The adder 431 outputs the voltage v q ' to the decoupling voltage v qa By adding q0 (An example of a first voltage command value) is generated. q0 is output to the control switching processor 70 and the first switch 81.

[0025] The d-axis current calculator 412 receives a d-axis current command value i d * and d-axis current detection value i d The d-axis current calculator 412 receives the d-axis current command value i d * and d-axis current detection value i d Calculate the difference between d to the d-axis current controller 422. The d-axis current controller 422 outputs the difference value Δi d Based on the voltage v d ' is calculated. Voltage v d The adder 432 outputs the voltage v d ' to the decoupling voltage v da By adding d0 (An example of a first voltage command value) is generated. d0 is output to the control switching processor 70 and the second switch 82.

[0026] The command torque calculation unit 50 calculates the q-axis current command value i q * and d-axis current command value i d * Torque command value T of synchronous motor M * and the torque command value T *to a second voltage command value generating unit 60. The second voltage command value generating unit 60 includes a current torque calculating unit 61, an adder 62, a switch 63, a phase angle controller 64, and an output voltage vector generating unit 65. Here, α indicates the phase (also referred to as the voltage phase) of the output voltage vector V from the q axis, as shown in Fig. 2B.

[0027] The current torque calculation unit 61 calculates the d-axis current detection value i d and q-axis current detection value i q The current torque T (an example of an actual torque) of the synchronous motor M is generated from the torque command value T * The adder 62 receives the torque command value T * and the current torque T, and outputs the torque difference value ΔT to a phase angle controller 64 via a switch 63.

[0028] The phase angle controller 64 is a PI controller, and generates a phase (voltage phase α of the output voltage vector) that makes the torque difference value ΔT zero. The generated voltage phase α is input to the output voltage vector generating unit 65. The output voltage vector generating unit 65 calculates the voltage phase α and the voltage amplitude v L to the q-axis voltage command value v q1 and d-axis voltage command value v d1 (an example of a second voltage command value) is generated, and the q-axis voltage command value v q1 to the first switch 81, and the d-axis voltage command value v d1 is output to the second switch 82.

[0029] The control switching processing unit 70 receives the q-axis current command value i q * and d-axis current command value i d * , command angular velocity ωe * , DC voltage V dc Based on this, the control mode is switched between maximum torque / current control mode and flux-weakening control mode.

[0030] When the maximum torque / current control mode is selected, the control switching processing unit 70 changes the d-axis voltage command value v d0 and the q-axis voltage command value v q0 The first switch 81 and the second switch 82 are each controlled to be switched to terminal “1” so as to output the signal to the drive unit 10.

[0031] When a mode transition from the maximum torque / current control mode to the flux-weakening control mode is selected, the control switching processor 70 switches the switch 63 to the terminal “1” (the output side of the adder 62). d1 and the q-axis voltage command value v q1 to the drive unit 10. The control of switching between the maximum torque / current control mode and the flux-weakening control mode will be described in detail later.

[0032] FIG. 2A shows an example of the trajectory of the current vector in the maximum torque / current control mode and the flux-weakening control mode with a solid line. In FIG. 2A, the vertical axis indicates the q-axis current, and the horizontal axis indicates the d-axis current. The dashed arc is a constant current circle. In the maximum torque / current control mode, the current vector transitions in the order of ai, bi, ci, and di as the command speed increases. Specifically, the voltage applied to the synchronous motor M increases as the command speed increases, and both the d-axis current and the q-axis current increase. In the maximum torque / current control mode, the current is controlled so that the composite torque of the magnet torque and the reluctance torque is maximized. Here, the angle β represents the phase (current phase) from the q-axis of the current vector transitioning on the maximum torque / current control curve. The curve showing the trajectory of the current vector from ai to di is the maximum torque / current control curve.

[0033] When the command speed increases further from point ci in Figure 2A and the current vector reaches point di, the inverter output voltage becomes saturated due to the effect of back electromotive force. When the voltage becomes saturated, the inverter cannot output a higher voltage to the synchronous motor M. The maximum output voltage from the inverter is v ovIf this is the case, in order to further increase the rotation speed of the synchronous motor M from this state, it is necessary to change the control mode and apply flux-weakening control.

[0034] FIG. 2B shows voltage vectors in the dq plane, with the vertical axis representing the q-axis voltage and the horizontal axis representing the d-axis voltage. Point dv in the figure is also the voltage saturation point corresponding to point di in FIG. 2A. dv(v ov In order to increase the rotation speed of the synchronous motor M that has reached the point 100), it is necessary to switch to the flux-weakening control mode.

[0035] The flux-weakening control mode will be described with reference to FIG. 2B. As shown in FIG. 2B, in the flux-weakening control mode, the voltage vector has a voltage amplitude v L and the voltage phase α. And the voltage amplitude v L v ov The voltage vector is controlled by fixing the voltage phase α to dv(v ov ) The voltage vector at point 1 is the voltage amplitude v L V ov , and the voltage phase α is αd. In order to further increase the rotation speed of the synchronous motor M, the voltage amplitude v L is fixed and the voltage phase α is increased. This causes the voltage vector to change to dv(v ov ) point to ev point. The voltage vector at ev point has a voltage amplitude v L is the maximum value v ov , the voltage phase α is αe.

[0036] At this time, the current vector transitions from point di to point ei as shown in Fig. 2A. In other words, by increasing the d-axis current of the current vector to increase the reluctance torque, the rotation speed of the synchronous motor M can be further increased.

[0037] (Configuration of a motor control device in maximum torque / current control mode) In the maximum torque / current control mode, in the motor control device 1 of FIG. 1, the first switch 81 and the second switch 82 are each set to the terminal "1" side. Fig. 3 is a block diagram showing the main configuration of the motor control device 1 in the maximum torque / current control mode according to the first embodiment. In Fig. 3, the same parts as those in Fig. 1 are given the same reference numerals and detailed description will be omitted.

[0038] The motor control device 1A in FIG. 3 includes a first current sensor 151, a second current sensor 152, a three-phase / two-phase conversion unit 20, a q-axis command current generation unit B16, a d-axis command current generation unit B24, a q-axis current calculator B25, a d-axis current calculator B26, a q-axis current controller 421, a d-axis current controller 422, an adder 431, and a d-axis voltage calculator B30.

[0039] The first current sensor 151 detects the U-phase current i u The second current sensor 152 detects the amplitude of the W-phase current i w The three-phase / two-phase converter 20 detects the amplitude of the current vector (i u ,i v ,i w ) is the d-axis current detection value i d and q-axis current detection value i q and converts the q-axis current detection value i q is output to the q-axis current calculator B25, and the d-axis current detection value i d is output to the d-axis current calculator B26.

[0040] Here, the q-axis command current generating unit B16 generates the q-axis current command value i based on the input speed difference value Δωe. q * and the q-axis current command value iq * The d-axis command current generating unit B24 outputs the q-axis current command value i q * to d-axis current command value i d * and the d-axis current command value i d * is output to the d-axis current calculator B26.

[0041] The q-axis current calculator B25 calculates the q-axis current command value i q * and the q-axis current detection value i q Calculate the difference between q to the q-axis current controller 421. The q-axis current controller 421 outputs the difference value Δi q Based on the voltage v q ' is calculated. Voltage v q The adder 431 outputs the voltage v q ' to the decoupling voltage v qa By adding q0 The q-axis voltage command value v q0 is output to the two-phase / three-phase conversion unit 11.

[0042] The d-axis current calculator B26 calculates the d-axis current command value i d * and d-axis current detection value i d Calculate the difference between d to the d-axis current controller 422. The d-axis current controller 422 outputs the difference value Δi d Based on the voltage v d ' is calculated. Voltage v d The adder 432 outputs the voltage v d ' to the decoupling voltage v da By adding d0 The d-axis voltage command value v d0 is output to the two-phase / three-phase conversion unit 11.

[0043] (Explanation of operation in maximum torque / current control mode) In Figure 3, ωe * , ωe are the angular velocity command value in electrical angle and the actual angular velocity of the rotor, and the actual angular velocity may be calculated by a speed sensor that calculates the angular velocity from an actual measurement value obtained by an angle sensor such as an encoder or a Hall element, or may be calculated by a speed sensor that calculates the angular velocity from an actual measurement value obtained by a position measuring device using a shunt current. Here, a speed sensor that calculates the angular velocity from an actual measurement value is used.

[0044] Command angular velocity ωe* The difference value Δωe between the actual angular velocity ωe (angular velocity ωe) is input to the q-axis command current generating unit B16, and the q-axis current command value i q * A PI controller is generally used for the speed controller 32 (q-axis command current generator B16 and d-axis command current generator B24), and feedback control is applied so as to make the speed difference zero. On the other hand, the d-axis command current generating unit B24 generates the d-axis current command value i d * The q-axis current command value i q * It is calculated as a function of (Equation 1).

[0045]

number

[0046] Here, ψa is the armature flux linkage of the permanent magnet rotor (line-to-line effective value), L d , L q are the winding inductances in the d-axis and q-axis directions.

[0047] d-axis current command value i d * and the q-axis current command value i q * The angle difference between the current vector due to this and the q-axis is the advance angle β in FIG. 2A, and (Equation 1) is a relational expression for combining the magnet torque and reluctance torque so that the torque per current is maximized.

[0048] d-axis current command value i d * is the d-axis current detection value i d is compared with the difference value Δi d is input to the d-axis current controller 422. The q-axis current command value i q * is the q-axis current detection value i q is compared with the difference value Δi q is input to the q-axis current controller 421. The q-axis current controller 421 controls the voltage v q The d-axis current controller 422 outputs the voltage v d' is output.

[0049] The voltage v output from the q-axis current controller 421 q ', the decoupling voltage v qa is added, and the q-axis voltage command value v q0 The voltage v output from the d-axis current controller 422 is d ', the decoupling voltage v da is added, and the d-axis voltage command value v d0 It becomes.

[0050] Decoupling voltage v qa, v da is the voltage for canceling the mutual interference between the d-axis and q-axis, and is given by (Equation 2) and (Equation 3).

[0051]

number

[0052] Finally, the q-axis voltage command value v q0 and d-axis voltage command value v d0 is converted to v by the two-phase / three-phase conversion unit 11. u , v v , v w The three-phase voltage value v u , v v , v w According to the above, the DC voltage V dc This is modulated by PWM or the like to supply driving power to the synchronous motor M.

[0053] In the case of a three-phase motor, the actual current is at least two phases (i u , i w ) is detected, and the d-axis current detection value i d and q-axis current detection value i q The coordinates are transformed into and applied to the control.

[0054] The detection of the current value is not limited to a sensor, and for example, the current of a shunt resistor (not shown) connected in series to the power device may be used.

[0055] The mechanical angular velocity ωm is proportional to the number of pole pairs (P n ) to obtain the electrical angular velocity ωe, which is integrated (1 / s) to obtain the rotor rotation angle θe (rotor phase angle θe expressed in electrical angle). In accordance with this rotation angle θe, two-phase / three-phase conversion unit 11 and three-phase / two-phase conversion unit 20 perform coordinate conversion.

[0056] By repeating these processes, motor control device 1A drives synchronous motor M along the maximum torque / current control curve shown in Fig. 2A. The above is the operation in the maximum torque / current control mode.

[0057] (Configuration of a motor control device in flux-weakening control mode) In the flux-weakening control mode, in the motor control device 1 of FIG. 1, the first switch 81 and the second switch 82 are each set to the terminal "2" side. Fig. 4 is a block diagram showing the configuration of a motor control device 1B for a flux-weakening control mode according to the first embodiment. In Fig. 4, the same parts as those in Fig. 1 are given the same reference numerals and detailed description thereof will be omitted.

[0058] The speed controller 32 (q-axis command current generator B16 and d-axis command current generator B24) in the motor control device 1B in FIG. 4 is the same as that in FIG. 3. That is, the q-axis command current generator B16 derives a q-axis current command value i from the input difference value Δωe. q * The d-axis command current generating unit B24 generates the q-axis current command value i q * to d-axis current command value i d * and the d-axis current command value i d * to command torque calculation unit 50. Therefore, the configuration of speed controller 32 (q-axis command current generation unit B16 and d-axis command current generation unit B24) can be standardized in the motor control device in the maximum torque / current control mode shown in Fig. 3 and the flux-weakening control mode shown in Fig. 4.

[0059] (Explanation of operation in flux-weakening control mode) The output voltage from the inverter is the maximum value v ov When the maximum torque / current control mode is reached, the control mode is switched from the maximum torque / current control mode to the flux-weakening control mode, which corresponds to point di in FIG. 2A and point dv in FIG. 2B.

[0060] The voltage amplitude v represents the magnitude of the voltage vector at this time. L v ov As the output voltage amplitude v L The maximum value v ov is a value that is determined in advance and is set to a value equal to or lower than the voltage that the inverter can output.

[0061] After the transition to the flux-weakening control mode, the q-axis current command value i generated by the q-axis command current generating unit B16 and the d-axis command current generating unit B24 is q * and d-axis current command value i d * is input to the command torque calculation unit 50. In the command torque calculation unit 50, the command value T * Calculate.

[0062]

number

[0063] On the other hand, the current output torque T is the current d-axis current detection value i d and q-axis current detection value i q It is calculated using (Equation 5).

number

[0064] The speed controller 32 (q-axis command current generator B16 and d-axis command current generator B24) is common to the speed controller in the maximum torque / current control mode. Therefore, the q-axis current command value i q* and d-axis current command value i d * is a value on the maximum torque / current control curve. Specifically, during flux-weakening control, the q-axis current value and the d-axis current value are calculated at a point (for example, point fi) on the extension line of point di in Fig. 2A (the curve shown by the dashed line).

[0065] The q-axis current command value i calculated by the q-axis current command generator B16 and the d-axis current command generator B24 q * and d-axis current command value i d * is input to the command torque calculation unit 50. Then, the current command value is calculated as the torque command value T * Convert to.

[0066] The torque command value T output from the command torque calculation unit 50 * A torque difference value ΔT between the current torque T output from the current torque calculation unit 61 and the current torque α is input to a phase angle controller 64, which generates a voltage phase α. The phase angle controller 64 can be configured, for example, by a normal PI controller.

[0067] The voltage phase α output from the phase angle controller 64 is determined by the voltage amplitude v L The output voltage vector generating unit 65 generates a two-phase d-axis voltage command value v d1 and the q-axis voltage command value v q1 is calculated using the following formula:

[0068]

number

[0069] In the subsequent processing, similarly to the maximum torque / current control mode, the voltage is inversely converted to a three-phase voltage by the two-phase / three-phase conversion unit 11, and power is supplied to the synchronous motor M by the power conversion unit 12. The above process is repeated to continue constant voltage operation (flux-weakening control).

[0070] <Prevention of frequent mode switching> The following describes processing for preventing frequent mode switching (hereinafter also referred to as hunting prevention processing) at the switching point between the maximum torque / current control mode and the flux-weakening control mode.

[0071] For example, in an actual system, the command value may not be stable near the switching point of the control mode, and the switching point may frequently go back and forth (so-called hunting) due to the load state of the synchronous motor M or the influence of pulsation or noise components of the control signal applied to the synchronous motor M. In this case, if the control mode is switched every time the switching point goes back and forth, there is a risk that motor control will break down and the motor will stop due to loss of synchronization.

[0072] In order to reduce such a risk, multiple switching points of the control mode may be provided. Specifically, the control operation of the switching points is performed as shown in Fig. 5A and Fig. 5B. The figures show a dq plane, with Fig. 5A being a diagram explaining the switching operation for the current transition, and Fig. 5B being a diagram explaining the switching operation for the voltage transition. In Fig. 5A, the vertical axis indicates the q-axis current, and the horizontal axis indicates the d-axis current. In Fig. 5B, the vertical axis indicates the q-axis voltage, and the horizontal axis indicates the d-axis voltage.

[0073] The arrow (1) in FIG. 5A indicates the direction of change in the q-axis current value and the d-axis current value as the rotation speed of the synchronous motor M increases after starting from the origin 0 in the maximum torque / current control mode. The current value increases until it reaches the switching point di from the maximum torque / current control mode to the flux-weakening control mode in FIG. 5A. FIG. 5B shows the voltage amplitude value (maximum value) v at point dv, which corresponds to point di in FIG. 5A. ov is illustrated.

[0074] When the DI point in Figure 5A is reached (the output voltage is ov When the output voltage vector reaches the voltage amplitude v L V ov, and the voltage phase α is increased to generate torque mainly due to the d-axis current. The arrows (2) in Fig. 5A and Fig. 5B indicate the direction of change in the current value and voltage value when the voltage phase α increases in the flux-weakening control mode. Note that the voltage amplitude value v ov and the voltage phase αd are stored in the control switching processor 70.

[0075] Arrow (3) in Figures 5A and 5B indicates the direction of change in the current value and voltage value when the voltage phase α decreases in the flux-weakening control mode. This indicates a state in which the rotation speed of the synchronous motor M decreases, for example, in response to the rotation speed command value, after the synchronous motor M reaches point ei in Figure 5A (point ev in Figure 5B). Then, the synchronous motor M reaches point di in Figure 5A (point dv in Figure 5B).

[0076] In this embodiment, the switching point from the flux-weakening control mode to the maximum torque / current control mode is point dv' in Fig. 5B. That is, even if the rotation speed of the synchronous motor M is reduced according to the rotation speed command value after the synchronous motor M reaches point dv in Fig. 5B, the flux-weakening control mode is maintained. In the flux-weakening control mode, the voltage vector (voltage amplitude value and voltage phase) is controlled as the voltage command value. Therefore, in order to reduce the rotation speed of the synchronous motor M from point dv in Fig. 5B, the voltage vector is reduced so that the current vector is approximately along the maximum torque / current control curve.

[0077] The direction of change in the voltage command value that reduces the rotation speed of the synchronous motor M while keeping the current vector roughly along the maximum torque / current control curve is shown by the arrow (4) in FIG. 5B. Specifically, in the flux-weakening control mode, the voltage phase α is changed to α 0 5B, the control switching processor 70 switches the control mode from the flux-weakening control mode to the maximum torque / current control mode. The voltage amplitude value at the point dv' is fixed to v uv Let us assume that. uv The value of is preset as the system operating value, and the magnitude of the voltage vector is v uvWhen it falls below this value, it switches to maximum torque / current control mode.

[0078] As described above, the switching point from the flux-weakening control mode to the maximum torque / current control mode is set to be different from the switching point to the maximum torque / current control mode, thereby making it possible to prevent frequent mode switching at the switching points between the maximum torque / current control mode and the flux-weakening control mode.

[0079] (Operation of the control switching processing unit 70) Next, the operation of the control switching processor 70 will be described in detail. The output voltage in the maximum torque / current control mode is determined by adding the non-interference voltage v da , v qa The d-axis voltage command value v d0 and the q-axis voltage command value v q0 Therefore, the magnitude of the voltage applied to the power conversion unit 12 is v r is calculated by the following formula:

[0080]

number

[0081] Furthermore, r may be passed through a low-pass filter (LPF) to remove pulsation and noise.

[0082] In the maximum torque / current control mode, the first switch 81 and the second switch 82 are connected to the terminal “1”, and the d-axis voltage command value v d0 and the q-axis voltage command value v q0 is transmitted to the next processing stage.

[0083] v r and v ovIf the condition of (Equation 9) is satisfied, the control switching processor 70 performs an initialization process for transitioning to the flux-weakening control mode, which will be described later. Furthermore, the control switching processor 70 switches the first switch 81 and the second switch 82 from terminal "1" to terminal "2". As a result, the output of the output voltage vector generator 65 on the flux-weakening control side is transmitted to the two-phase / three-phase converter 11, which is the next stage. In the initialization process when switching from the maximum torque / current control mode to the flux-weakening control mode, the switch 63 is set to the terminal "1" side.

[0084]

number

[0085] In addition, the following operations are performed during initialization when switching from maximum torque / current control mode to flux-weakening control mode.

[0086] First, for example, the control switching processor 70 calculates the voltage phase (initial voltage phase α1) when the maximum torque / current control mode is switched to the flux-weakening control mode from (Equation 10). Here, |*| is the absolute value, and α 0 is a small positive angle (rad) and an appropriate value is determined in advance. The initial voltage phase α1 is the d-axis voltage command value v d0 and the q-axis voltage command value v q0 If we use the voltage vector at the switching point dv, then v d0 / v q0 Here, the voltage command value at the switching point dv (v d0 and v q0 ) is already output in the maximum torque / current control mode immediately before the mode transition, so the voltage command value after the mode transition is the above-mentioned angle (v d0 / v q0 (arc tangent of) to a small angle α 0 It is recommended to add α 0 = 0).

[0087]

number

[0088] The control switching processing unit 70 controls the voltage amplitude v L v ov The output voltage vector generator 65 fixes the voltage amplitude v L From the initial voltage phase α1, the d-axis voltage command value v d1 , q-axis voltage command value v q1 Determine the initial value of .

[0089] Next, the values ​​(integrated values) held by the integrators included in each PI controller, such as the speed controller 32, the d-axis current controller 422, the q-axis current controller 421, and the phase angle controller 64 shown in Fig. 1, are updated (hereinafter, also referred to as correcting the integrators). Fig. 6 illustrates the configuration of a typical PI integrator. The integrator 112 updates the proportional gain K P and the integral gain K of the gain controller 111 I The control characteristics are determined by the setting of the proportional gain K P and the integral gain K of the gain controller 111 I takes different values ​​for the speed controller 32, the d-axis current controller 422, the q-axis current controller 421, and the phase angle controller 64.

[0090] First, when equation (9) is satisfied and the mode is switched to the flux-weakening control mode, the phase angle controller 64 is initialized. The integrator (not shown) of the phase angle controller 64 outputs a voltage amplitude v L Since the phase angle of is held, the integrator is initialized using α1 in (Equation 10) as the initial value.

[0091] This completes the initialization process when switching from the maximum torque / current control mode to the flux-weakening control mode.

[0092] Even after the transition to the flux-weakening control mode, the current controllers that are corrected for each control period are the d-axis current controller 422 and the q-axis current controller 421. The d-axis current controller 422 and the q-axis current controller 421 used in the maximum torque / current control mode are controlled by the v d0 ',v q0 The control switching processing unit 70 holds v d1 ,v q1 , decoupling voltage v da ,v qa The integrators of the d-axis current controller 422 and the q-axis current controller 421 are corrected using a value calculated by the following equation:

[0093]

number

[0094] On the other hand, the virtual voltage vector is the virtual command voltage v m Define the virtual command voltage v m is the virtual d-axis voltage v calculated by the motor model formula (Equation 13 to Equation 14). dm and the virtual q-axis voltage v qm The virtual d-axis voltage v dm and the virtual q-axis voltage v qm is the d-axis current command value i generated by the speed controller 32. d * and the q-axis current command value i q * is substituted into the motor model equations (Equations 13 to 14) to calculate.

[0095] q-axis current command value i q * and d-axis current command value i d * is a value on the maximum torque / current control curve. Therefore, the q-axis current command value i q * and d-axis current command value i d * exists on the extension line (the curve shown by the dashed line) of point di in FIG. 2A (for example, point fi shown in FIG. 2A). Also, the virtual command voltage value v m corresponds to point fv shown in FIG. 2B.

[0096] As shown in FIG. 3 and FIG. 4, the d-axis current command value i generated by the q-axis command current generating unit B16 and the d-axis command current generating unit B24 is d * and the q-axis current command value i q * is input to the control switching processor 70. The control switching processor 70 receives the d-axis current command value i d * and the q-axis current command value i q * From the virtual command voltage value v m is calculated from the motor model equations (Equations 13 to 14).

[0097]

number

[0098] v m is a virtual voltage for flowing a current along the maximum torque / current control curve in Figure 2A. After transitioning to the flux-weakening control mode (also called the flux-weakening region), the voltage value exceeds the saturation voltage (v in Figure 2B). m ). Therefore, v m cannot be used as a voltage command value. m is used to determine whether the current vector has returned to the maximum torque / current control curve, as will be described later.

[0099] The control switching processing unit 70 stores the switching point from the maximum torque / current control mode to the flux-weakening control mode, and stores the virtual command voltage v m The value of v s and stores the result in a memory (not shown).

[0100] In addition, in FIG. 1, the dashed arrows superimposed on the q-axis current controller 421, the d-axis current controller 422, and the phase angle controller 64 indicate that the control switching processing unit 70 performs rewrite control on each integrator.

[0101] Next, a process for switching from the flux-weakening control mode to the maximum torque / current control mode will be described.

[0102] FIG. 7 is a flowchart showing a control process procedure of the control switching processor 70 in the flux-weakening control mode. The control switching processing unit 70 executes a voltage correction process described later (step ST9a), and determines (branch determination) whether a flux weakening process or a voltage amplitude reduction process is being performed based on the conditions of (Equation 16) and (Equation 17) (step ST9b).

[0103]

number

[0104] Output voltage amplitude v L is the maximum value v ov If it is equal to (Equation 16) (Y in step ST9b), the control switching processor 70 determines that flux-weakening processing is being performed (the state is indicated by arrow (2) or arrow (3) in FIG. 5A) and continues the flux-weakening processing (step ST9c). If it is not (Equation 17) (N in step ST9b), it determines that voltage amplitude reduction processing is being performed (the state is indicated by arrow (4) in FIG. 5A) and continues the voltage amplitude reduction processing (step ST9d). Equation 17 is used as the initial value for flux-weakening control, v L is v ov Since we hold v as the maximum value, L V ov It cannot be greater than v L <v ov is determined to be equivalent to

[0105] FIG. 8 is a flowchart showing the details of the flux-weakening process shown in FIG. The process branches according to the following formula:

[0106]

number

[0107] The control switching processing unit 70 is L =v ov In the state of (Equation 18: arrow (2) and arrow (3) in FIG. 5A), it is determined whether the current vector has returned to point di shown in FIG. 5A and point dv shown in FIG. 5B based on (Equation 18) and (Equation 19) (step ST10a). Specifically, when the magnitude of the voltage vector reaches the maximum value v ov It is determined whether the following occurs:

[0108] v m is the virtual command voltage value according to (Equation 15), and v s is the v when entering the flux-weakening control mode. m The control switching processing unit 70 controls the V m Then, when the control mode is switched to the flux-weakening control mode, the control switching processing unit 70 continues to calculate the calculated v m v s The control switching processing unit 70 stores the result in a memory (not shown) as v m V s If it is determined that the value is greater than the value (Equation 18) (Y in step 10a), the flux-weakening control mode (arrows (2) and (3) in FIG. 5A and FIG. 5B) is continued. m V s When it is determined that the following (Equation 19) is satisfied (N in step ST10a), the voltage amplitude reduction process is executed to cancel the flux-weakening control mode (arrow (4) in FIGS. 5A and 5B).

[0109] In addition, in determining whether or not to start the voltage amplitude reduction process (step ST10a), v r Instead, the virtual command voltage value v m Explain why we use v r The d-axis voltage command value v d0 and the q-axis voltage command value v q0 The q-axis current controller 421 and the d-axis current controller 422 are used to generate the d-axis voltage command value v. The integrators of the q-axis current controller 421 and the d-axis current controller 422 are rewritten by the control switching processor 70 with the voltage value in the flux-weakening control mode. d0and the q-axis voltage command value v q0 does not necessarily have the voltage value in maximum torque / current control mode.

[0110] (Equation 18) is true (v m V s If the voltage amplitude v of the voltage vector is greater than the threshold voltage, the control switching processor 70 continues the flux weakening process. L The value of v continues to be the maximum ov (step ST10b), and the flux-weakening control mode is maintained by (Equation 16). Then, the control switching processor 70 generates a voltage phase α by the phase angle controller 64 (step ST10c), and sets the d-axis voltage command value v d1 and the q-axis voltage command value v q1 is newly calculated as a voltage according to the voltage phase α (step ST10d).

[0111] On the other hand, if it is determined in step ST10a that (Equation 19) holds (N in step ST10a), the control switching processor 70 enters the state indicated by arrow (4) in FIGS. 5A and 5B, and the voltage amplitude reduction process is started.

[0112] When the voltage amplitude reduction process is started, the control switching processor 70 judges whether the determination formula (Formula 20) is true (v r V ov In the determination formula, the d-axis voltage command value v d0 and the q-axis voltage command value v q0 v is calculated by r is the saturation voltage value v ov As a result, if the determination formula (Formula 20) is true (Y in step ST10e), the control switching processing unit 70 adjusts the voltage amplitude v L As the value of v in (Eq. 8), r On the other hand, if the judgment formula (Formula 20) is false (N in step ST10e), the control switching processing unit 70 uses the value of the voltage amplitude v L The maximum value of v ov maintain.

[0113]

number

[0114] v r is the PI output voltage v of the d-axis current controller 422 and the q-axis current controller 421 of the maximum torque / current control. d0 ,v q0 Therefore, if formula 20 is satisfied, the output voltage in the maximum torque / current control mode will be equal to or lower than the saturation voltage. Therefore, the control switching processor 70 executes a process to reduce the voltage amplitude.

[0115] In the "voltage amplitude reduction processing mode", the control switching processing unit 70 still maintains the flux-weakening control mode. Therefore, the output voltage vector generating unit 65 generates the q-axis voltage command value v q1 and d-axis voltage command value v d1 is calculated (step ST10g), but the current value of the α angle is maintained. Specifically, by switching the switch 63 to the terminal "2", the PI of the phase angle controller 64 is not updated, and the voltage phase (αd) held by the integrator is output as is.

[0116] In addition, the control switching processing unit 70 corrects the integrators of the q-axis current controller 421 and the d-axis current controller 422 according to (Equation 11) and (Equation 12) (step ST10h). By setting the integrators of the q-axis current controller 421 and the d-axis current controller 422 to the same value as the current output voltage value, the v r The value of can be calculated. Voltage amplitude of the voltage vector v L is the maximum value v ov If it is set as a smaller voltage value, the branching decision in FIG. 7 determines that the condition of (Equation 17) is satisfied (N in step ST9b), and the process branches to "voltage amplitude reduction process."

[0117] FIG. 9 is a flowchart showing details of the voltage amplitude reducing process shown in FIG. The control switching processing unit 70 calculates the voltage amplitude v LThe value of the maximum torque / current control process of the output voltage V r Using (step ST11a), v L V ov It is determined whether the value exceeds the threshold (step ST11b). L (v r ) is v ov If it exceeds (Y in step 11b), v L The value of v ov (Step ST11c), and the q-axis voltage command value v q1 and d-axis voltage command value v d1 (Step ST11d). Therefore, in the next period, the branching decision in FIG. 7 determines that the condition of (Equation 16) is satisfied (Y in Step ST9b), and the process branches again to "flux-weakening process" (Step ST9c).

[0118] On the other hand, the control switching processing unit 70 determines the voltage amplitude v L V ov If it is determined that the q-axis voltage command value v q1 and d-axis voltage command value v d1 (step ST11e), and then the following equation is judged (step ST11f).

[0119]

number

[0120] v ud is the voltage value at which the control mode returns to maximum torque / current control mode from the flux-weakening mode, and v ov and v ud By providing hysteresis with this, stable transition processing that does not cause hunting is achieved.

[0121] If the judgment formula (Formula 21) is false (N in step ST11f), the control switching processing unit 70 L V ud It is determined that the voltage amplitude has not yet been sufficiently reduced, and the integrators of the d-axis current controller 422 and the q-axis current controller 421 are corrected to continue the voltage amplitude reduction process. Finally, if (Equation 21) is satisfied (Y in step ST11f), the control switching processor 70 corrects the integrators of the d-axis current controller 422 and the q-axis current controller 421, and transitions to the maximum torque / current control mode (step ST11g).

[0122] Note that the control switching processor 70 always corrects the integrators provided inside the d-axis current controller 422 and the q-axis current controller 421 even during flux-weakening control (step ST11h). This allows the integrators of the q-axis current controller 421 and the d-axis current controller 422 to be able to handle switching between the flux-weakening control mode and the maximum torque / current control mode without complicating the control of the control switching processor 70.

[0123] (Voltage correction processing) The "voltage correction process" in the flow of FIG. 7 will be described. v ov and v ud For example, DC voltage V dc is assumed to be constant. Therefore, v ov and v ud is the DC voltage V dc It is assumed that the ratio of v to v is determined as follows (for convenience, v ov0 , v ud0 (They state that.)

[0124]

number

[0125] where over_ratio and under_ratio are coefficients for obtaining the voltage at which the flux-weakening control mode is entered and the voltage at which the maximum torque / current control mode is returned to. ud V ov It is previously determined to be a value lower than The division of root 2 is the coefficient when transforming from a fixed coordinate system to a rotating coordinate system by absolute transformation at a modulation rate of 100%.

[0126] DC voltage V dcIn reality, this may fluctuate due to converter fluctuations, AD conversion errors, etc. Voltage correction processing is performed to reflect this fluctuation.

[0127] For example, v ov ≠v ov0 At this time, the control switching processing unit 70 controls the DC voltage V dc is judged to have fluctuated and the following correction is performed.

[0128]

number

[0129] The control switching processing unit 70 calculates v L , v s , v ov , v ud This corrects the DC voltage V dc Therefore, even if a voltage fluctuation occurs, it can be prevented from affecting motor control.

[0130] <Effects of the First Embodiment> As described above, in the maximum torque / current control mode, the d-axis current command value i d * and q-axis current command value i q * and the d-axis current detection value i d and q-axis current detection value i q The voltage command value v is generated based on the difference between q0 ,v d0 is output to the drive unit 10. On the other hand, in the flux-weakening control mode, the d-axis current command value i d * and q-axis current command value i q * By continuing to use this, the torque command value T of the synchronous motor M is * Then, the torque command value T * and the current torque T of the synchronous motor M. q1 ,v d1 is output to the driving unit 10.

[0131] Therefore, the speed controller 32 that generates the current command value can perform continuous operation regardless of switching between the maximum torque / current control mode and the flux-weakening control mode. In other words, the speed controller 32 of the motor control device 1 can be used in common for both the maximum torque / current control mode and the flux-weakening control mode. This improves the stability of the motor control device 1 and makes it easier to design.

[0132] In addition, the d-axis current command value i d * and q-axis current command value i q * and the d-axis current detection value i d and q-axis current detection value i q By relating the above through a torque equation, discontinuities in control can be avoided and continuous control can be easily performed.

[0133] Furthermore, the d-axis current command value i d * and the q-axis current command value i q * From the virtual command voltage value v m Calculate the virtual command voltage v m is the voltage for flowing current along the maximum torque / current control curve. Even in the flux-weakening region, the voltage value that virtually exceeds the saturation voltage is calculated. Therefore, when initializing the mode transition, the virtual command voltage value v at the boundary between the maximum torque / current control mode and the flux-weakening control mode is m By storing this in memory, it is possible to switch from the maximum torque / current control mode to the flux-weakening control mode with high accuracy.

[0134] In addition, in the control switching processing unit 70, the voltage command value v q0 ,v d0 and the voltage command value v q0 ,v d0 Based on this, it is also possible to switch from maximum torque / current control mode to flux-weakening control mode.

[0135] In addition, when switching from the flux-weakening control mode to the maximum torque / current control mode, in order to make the switching smoother, the voltage amplitude v L When the current returns to the dv point and then drops to the dv' point, which is smaller than the dv point, the control mode is switched from the flux-weakening control mode to the maximum torque / current control mode. This prevents the control mode from switching frequently at the dv point, and enables stable driving without control hunting.

[0136] <Other embodiments> As described above, the present invention has been described by one embodiment, but the description and drawings forming part of this disclosure should not be understood as limiting the present invention. If the gist of the technical content disclosed in the above embodiment is understood, it will be clear to those skilled in the art that various alternative embodiments, examples and operation techniques can be included in the present invention. In addition, the configurations disclosed in one embodiment can be appropriately combined within a range that does not cause contradictions. For example, the configurations disclosed in multiple different embodiments may be combined, and the configurations disclosed in multiple different modified examples of the same embodiment may be combined. [Explanation of symbols]

[0137] 1,1A,1B Motor control device 10 Drive unit 11 2-phase / 3-phase conversion section 12 Power conversion section 13 Converter 14 Integrator 20 3-phase / 2-phase conversion section 31,B15 Arithmetic unit 32 Speed ​​Controller B16 q-axis command current generation section B24 d-axis command current generation section 40 First voltage command value generating unit 50 Command torque calculation unit 60 Second voltage command value generating unit 61 Current torque calculation unit 62 Adder 63 Switch 64 Phase Angle Controller 65 Output voltage vector generator 70 Control switching processing section 81 First Switch 82 Second Switch 110,111 Gain controller 112 Integrator (1 / s) 151 First current sensor 152 Second Current Sensor 411 q-axis current calculator 412 d-axis current calculator 421 q-axis current controller 422 d-axis current controller 431,432 Adder

Claims

1. a motor drive control unit that controls the drive of the motor in either a normal control mode or a flux-weakening control mode corresponding to saturation of a voltage applied to the motor in response to an input voltage command value; a conversion unit that converts a motor current flowing through the motor into a q-axis current and a d-axis current; a speed controller that generates a current command value based on a speed difference between a command angular velocity for the motor and an actual angular velocity of the motor; a first voltage command value generator that generates a first voltage command value based on a difference between the current command value and each of the q-axis current and the d-axis current; a torque command value generator that generates a torque command value for the motor from the current command value; a second voltage command value generator that generates a second voltage command value based on a difference between the torque command value and an actual torque of the motor; a control switching processing unit that switches between the normal control mode and the flux-weakening control mode based on the current command value, a control switching processing unit that outputs the first voltage command value to the motor drive control unit when the normal control mode is selected, and outputs the second voltage command value to the motor drive control unit when the flux-weakening control mode is selected.

2. 2. The motor control device according to claim 1, wherein the control switching processing unit further inputs the first voltage command value output from the first voltage command value generator, and switches from the normal control mode to the flux-weakening control mode when the first voltage command value exceeds a predetermined value.

3. 2. The motor control device according to claim 1, wherein the control switching processing unit calculates a q-axis voltage command value and a d-axis voltage command value from the current command value, and switches from the normal control mode to the flux-weakening control mode when a voltage vector constituted by the q-axis voltage command value and the d-axis voltage command value exceeds a predetermined value.

4. 3. The motor control device according to claim 2, wherein, when the predetermined value for switching from the normal control mode to the flux-weakening control mode is a first predetermined value, the control switching processing unit switches from the flux-weakening control mode to the normal control mode if a voltage vector constituted by the q-axis voltage command value and the d-axis voltage command value returns to the first predetermined value and drops to a second predetermined value that is smaller than the first predetermined value.

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