JP2023181776A - Control device for induction machine - Google Patents

Abstract

To reduce unnecessary torque caused by including an error in a rotation number of an induction machine in a case where the rotation number of the induction machine is relatively small.SOLUTION: A control device 1 is configured by including an inverter circuit 2 which drives an induction machine M and a control circuit 3 by which, in a case where a rotation number ω of the induction machine is larger than a rotation number threshold ωth1, the operation of the inverter circuit 2 is controlled by making an excitation current command value Id* into an excitation current command value Id*1 and making a torque current command value Iq* into a torque current command value Iq*1 and in a case where the rotation number ω is equal to or smaller than the rotation number threshold ωth1, the operation of the inverter circuit 2 is controlled in accordance with an excitation current command value Id*2, which is smaller than the excitation current command value Id1*, and the torque current command value Iq*1.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for an induction machine.

As an induction machine control device, the rotation speed of the induction machine is calculated from the period from the rise timing to the fall timing of the pulse signal corresponding to the edge of each tooth of the gear (gear) in the rotation sensor installed in the induction machine. There is a system that controls the operation of an inverter circuit that drives an induction machine based on the calculated rotation speed.

By the way, if there is an error in the period from the rise timing to the fall timing of the pulse signal due to manufacturing variations in gears, the calculated rotational speed will also include the error. For example, if the target torque current command value is zero and there is an error in the rotation speed, the vector of the excitation current command value calculated by the rotation speed that includes the error and the vector of the excitation current command value that flows through the induction machine A phase difference occurs between the excitation current vector and a torque current that would not normally be generated flows into the induction machine, causing the induction machine to generate unnecessary torque.

Therefore, as another control device for an induction machine, there is one that corrects the rotation speed using a correction value at the rise timing or fall timing of a pulse signal. A related technique is Patent Document 1.

However, in the other control devices described above, the rotation speed cannot be corrected at timings other than the rise timing and fall timing of the pulse signal, and there is a possibility that the calculated rotation speed may include an error. In particular, as the rotation speed decreases, the number of times when the rotation speed cannot be corrected increases, so that the calculated rotation speed is likely to include errors.

JP2018-78707A

An object of one aspect of the present invention is to control an induction machine that can reduce unnecessary torque generated due to an error in the rotation speed of the induction machine when the rotation speed of the induction machine is relatively small. The purpose is to provide equipment.

An induction machine control device according to one embodiment of the present invention includes an inverter circuit that drives an induction machine, and a rotation speed that is calculated based on a rotation speed command value input from the outside and a rotation speed based on a detection value of a rotation sensor. a control circuit that adjusts a torque command value so that the numerical deviation converges to zero, uses the torque command value to obtain an excitation current command value and a torque current command value, and controls the operation of the inverter circuit; Be prepared.

When the rotation speed of the induction machine is larger than a first rotation speed threshold, the control circuit sets the excitation current command value as a first excitation current command value, and sets the torque current command value as a first torque current command value. When the operation of the inverter circuit is controlled and the rotation speed is less than or equal to the first rotation speed threshold, a second excitation current command value smaller than the first excitation current command value, and a second excitation current command value smaller than the first torque current command value or the first torque current command value or the first torque current command value are set. The operation of the inverter circuit is controlled by a second torque current command value that is larger than the first torque current command value.

As a result, when the rotation speed of the induction machine is relatively small and the rotation speed tends to include errors, the vector of the excitation current command value and the vector of the excitation current can be made relatively small. The torque current generated due to the phase difference between the vector and the excitation current vector can be reduced, and unnecessary torque generated in the induction machine can be reduced.

The control circuit also controls the control circuit when the rotation speed is higher than the first rotation speed threshold, or when the rotation speed is less than or equal to the first rotation speed threshold and the output of the induction machine is larger than the first output threshold. , controlling the operation of the inverter circuit by setting the excitation current command value as a first excitation current command value and using the torque current command value as a first torque current command value, and controlling the operation of the inverter circuit when the rotation speed is equal to or less than the first rotation speed threshold. If the output of the induction machine is equal to or less than the first output threshold, the operation of the inverter circuit may be controlled by the second excitation current command value and the first torque current command value.

Thereby, when the rotation speed and output of the induction machine are relatively small, unnecessary torque generated in the induction machine can be reduced.

The control circuit also controls the control circuit when the rotation speed is higher than the first rotation speed threshold, or when the rotation speed is less than or equal to the first rotation speed threshold and the output of the induction machine is larger than the first output threshold. , the operation of the inverter circuit is controlled by setting the excitation current command value as a first excitation current command value and using the torque current command value as a first torque current command value, and the rotation speed is smaller than the first rotation speed threshold. If the output of the induction machine is smaller than a second rotation speed threshold and smaller than a second output threshold that is smaller than the first output threshold, a second excitation current command value that is smaller than the first excitation current command value and the first torque current If the operation of the inverter circuit is controlled by a command value, the rotation speed is smaller than the second rotation speed threshold, and the output of the induction machine is within a range from the second output threshold to the first output threshold, Controlling the operation of the inverter circuit using a third excitation current command value and the first torque current command value corresponding to an output of the induction machine within a range from the second excitation current command value to the first excitation current command value. do.

The control circuit also controls the second excitation when the rotation speed is within a range from the second rotation speed threshold to the first rotation speed threshold and the output of the induction machine is smaller than the second output threshold. The operation of the inverter circuit is controlled by a fourth excitation current command value corresponding to the rotation speed within a range from the current command value to the first excitation current command value, and the first torque current command value is controlled so that the rotation speed is is within the range from the second rotation speed threshold to the first rotation speed threshold, and when the output of the induction machine is within the range from the second output threshold to the first output threshold, the fourth excitation current The operation of the inverter circuit is controlled by a fifth excitation current command value and the first torque current command value corresponding to an output of the induction machine within a range from the command value to the first excitation current command value. It's okay.

As a result, it is possible to suppress the excitation current command value from dropping sharply when the rotational speed and output of the induction machine are relatively small, so that the user feels uncomfortable when the excitation current command value suddenly decreases. can be alleviated.

According to the present invention, when the rotation speed of the induction machine is relatively small, unnecessary torque generated due to an error included in the rotation speed of the induction machine can be reduced.

It is a diagram showing an example of a control device for an induction machine in an embodiment. FIG. 3 is a diagram showing an example of an excitation current command value and a current flowing through an induction machine. 5 is a flowchart showing the operation of a current command value output section in Example 1. FIG. 7 is a flowchart showing the operation of a current command value output section in Example 2. FIG. 7 is a flowchart showing the operation of a current command value output section in Example 3. FIG. 7 is a diagram for explaining the operation of a current command value output section in Embodiment 4. FIG. 2 is a diagram showing the relationship between the rotation speed of the induction machine, the output of the induction machine, and the excitation current threshold.

Embodiments will be described in detail below based on the drawings.

FIG. 1 is a diagram showing an example of an induction machine control device according to an embodiment.

A control device 1 shown in FIG. 1 controls the operation of an induction machine M mounted on a vehicle such as an electric forklift or an electric vehicle, and includes an inverter circuit 2 and a control circuit 3. Note that the induction machine M is, for example, a wound three-phase induction motor.

The inverter circuit 2 drives the induction machine M with the power supplied from the power supply P, and includes a capacitor C, switching elements SW1 to SW6 (for example, IGBT (Insulated Gate Bipolar Transistor)), a current sensor Se1, Se2. That is, one terminal of the capacitor C is connected to the positive terminal of the power supply P and the collector terminals of the switching elements SW1, SW3, and SW5, and the other terminal of the capacitor C is connected to the negative terminal of the power supply P and each of the switching elements SW2, SW4, and SW6. Connected to the emitter terminal. A connection point between the emitter terminal of switching element SW1 and the collector terminal of switching element SW2 is connected to the U-phase input terminal of induction machine M via current sensor Se1. A connection point between the emitter terminal of switching element SW3 and the collector terminal of switching element SW4 is connected to the V-phase input terminal of induction machine M via current sensor Se2. A connection point between the emitter terminal of the switching element SW5 and the collector terminal of the switching element SW6 is connected to the W-phase input terminal of the induction machine M.

Capacitor C smoothes the voltage output from power supply P and input to inverter circuit 2 .

The switching element SW1 is turned on or off based on the drive signal S1 output from the control circuit 3. The switching element SW2 is turned on or off based on the drive signal S2 output from the control circuit 3. Switching element SW3 is turned on or off based on drive signal S3 output from control circuit 3. Switching element SW4 is turned on or off based on drive signal S4 output from control circuit 3. Switching element SW5 is turned on or off based on drive signal S5 output from control circuit 3. Switching element SW6 is turned on or off based on drive signal S6 output from control circuit 3. By turning on or off the switching elements SW1 to SW6, the DC voltage output from the power supply P is converted into three AC voltages whose phases differ by 120 degrees from each other, and these AC voltages are connected to the U phase of the induction machine M, The voltage is applied to the V-phase and W-phase input terminals, and the rotor of the induction machine M rotates. That is, the inverter circuit 2 rotates the rotor of the induction machine M by turning on and off the switching elements SW1 to SW6.

The current sensor Se1 includes a Hall element, a shunt resistor, and the like, and detects the U-phase current Iu flowing in the U-phase of the induction machine M, and outputs the detected U-phase current Iu to the control circuit 3. Further, the current sensor Se2 is constituted by a Hall element, a shunt resistor, etc., detects the V-phase current Iv flowing in the V-phase of the induction machine M, and outputs the detected V-phase current Iv to the control circuit 3.

The control circuit 3 includes a storage section 4, a drive circuit 5, and a calculation section 6.

The storage unit 4 is composed of a RAM (Random Access Memory), a ROM (Read Only Memory), or the like.

The drive circuit 5 is composed of an IC (Integrated Circuit), etc., and uses the voltage value of a carrier wave (triangular wave, sawtooth wave, reverse sawtooth wave, etc.), the U-phase voltage command value Vu* output from the calculation unit 6, and the V-phase voltage command value Vu* output from the calculation unit 6. The voltage command value Vv* and the W-phase voltage command value Vw* are compared, and drive signals S1 to S6 according to the comparison results are output to the respective gate terminals of the switching elements SW1 to SW6.

For example, when the U-phase voltage command value Vu* is equal to or higher than the carrier wave voltage value, the drive circuit 5 outputs the high-level drive signal S1 and the low-level drive signal S2, and outputs the U-phase voltage command value Vu*. When Vu* is smaller than the voltage value of the carrier wave, a low-level drive signal S1 is output, and a high-level drive signal S2 is output. Further, when the V-phase voltage command value Vv* is equal to or higher than the voltage value of the carrier wave, the drive circuit 5 outputs the high-level drive signal S3 and the low-level drive signal S4, and outputs the V-phase voltage command value Vv*. When Vv* is smaller than the voltage value of the carrier wave, a low level drive signal S3 is outputted, and a high level drive signal S4 is outputted. Further, when the W-phase voltage command value Vw* is equal to or higher than the voltage value of the carrier wave, the drive circuit 5 outputs the high-level drive signal S5 and the low-level drive signal S6, and outputs the W-phase voltage command value Vw*. When Vw* is smaller than the voltage value of the carrier wave, a low level drive signal S5 is outputted, and a high level drive signal S6 is outputted.

The calculation section 6 is composed of a microcomputer or the like, and includes a rotation speed calculation section 7, a position calculation section 8, a current conversion section 9, a subtraction section 10, a torque command value calculation section 11, and a current command value output section 12. , a subtraction section 13 , a subtraction section 14 , a voltage command value calculation section 15 , and a voltage command value conversion section 16 . For example, by executing the program stored in the storage unit 4 by the microcomputer, the rotation speed calculation unit 7, the position calculation unit 8, the current conversion unit 9, the subtraction unit 10, the torque command value calculation unit 11, the current command value An output section 12, a subtraction section 13, a subtraction section 14, a voltage command value calculation section 15, and a voltage command value conversion section 16 are configured.

The rotation speed calculation unit 7 calculates the rotation speed ω of the induction machine M based on the rise timing and fall timing of a pulse signal Sp output from a rotation sensor En such as an encoder provided in the induction machine M. For example, the rotation speed calculation unit 7 counts the number of pulses of the pulse signal Sp input per second, multiplies the number of pulses by 2π, and divides the result by the number of gear teeth in the rotation sensor En. Find the rotational speed (angular velocity) ω.

The position calculation unit 8 calculates the position (phase angle) θ of the rotor of the induction machine M based on the rotation speed ω. For example, the position calculation unit 8 multiplies the rotational speed ω by a unit time (for example, 1 second) and sets the result as the position θ.

The current converter 9 determines the W-phase current Iw flowing through the W-phase of the induction machine M using the U-phase current Iu detected by the current sensor Se1 and the V-phase current Iv detected by the current sensor Se2.

Further, the current converter 9 uses the position θ calculated by the position calculator 8 to convert the U-phase current Iu, V-phase current Iv, and W-phase current Iw into an exciting current Id (field weakening to the induction machine M). (current component for generating torque) and torque current Iq (current component for generating torque in the induction machine M).

For example, the current converter 9 converts the U-phase current Iu, V-phase current Iv, and W-phase current Iw into the exciting current Id and the torque current Iq using the position θ and a conversion matrix for converting from three phases to two phases. Convert to

Note that the current detected by the current sensors Se1 and Se2 is not limited to the combination of the U-phase current Iu and the V-phase current Iv, but may be a combination of the V-phase current Iv and the W-phase current Iw, or the U-phase current Iu and W. A combination of phase currents Iw may also be used. When the V-phase current Iv and the W-phase current Iw are detected by the current sensors Se1 and Se2, the current converter 9 uses the V-phase current Iv and the W-phase current Iw to determine the U-phase current Iu. Further, when the U-phase current Iu and the W-phase current Iw are detected by the current sensors Se1 and Se2, the current converter 9 uses the U-phase current Iu and the W-phase current Iw to determine the V-phase current Iv.

In addition, in the case where the inverter circuit 2 further includes a current sensor Se3 that detects the current flowing in the W phase of the induction machine M in addition to the current sensors Se1 and Se2, the current converter 9 calculates the current flowing through the W phase of the induction machine M. The configuration may be such that the U-phase current Iu, V-phase current Iv, and W-phase current Iw detected by the current sensors Se1 to Se3 are converted into the excitation current Id and the torque current Iq using the position θ.

The subtraction unit 10 calculates a rotation speed deviation Δω between the rotation speed command value ω* inputted from the outside and the rotation speed ω calculated by the rotation speed calculation unit 7.

The torque command value calculation unit 11 calculates the torque command value T* using the rotation speed deviation Δω output from the subtraction unit 10. For example, the torque command value calculation unit 11 refers to information (not shown) stored in the storage unit 4 in which the rotation speed of the induction machine M and the torque of the induction machine M are associated with each other, and calculates the rotation speed. The torque corresponding to the rotational speed corresponding to the numerical deviation Δω is determined as the torque command value T*.

Further, the torque command value calculation unit 11 calculates the output Po of the induction machine M based on the rotation speed deviation Δω. The output Po of the induction machine M is the ratio of the torque currently being output according to the rotational speed deviation Δω to the maximum torque. For example, the torque command value calculation unit 11 calculates the output Po by calculating Equation 1 below. Note that the possible range of the output Po is -100[%] to +100[%].

Output Po = Proportional gain x Rotation speed deviation Δω + Integral gain x ∫ Rotation speed deviation Δωdt ... Formula 1

The current command value output unit 12 uses the torque command value T* to obtain an excitation current command value Id* and a torque current command value Iq*. For example, the current command value output unit 12 stores information (not shown) in which the torque of the induction machine M, the exciting current command value Id*, and the torque current command value Iq* are associated with each other, which is stored in the storage unit 4. ), an excitation current command value Id* and a torque current command value Iq* corresponding to the torque corresponding to the torque command value T* are determined.

In addition, the current command value output unit 12 outputs the excitation current command value Id* obtained from the torque command value T* based on the rotational speed ω and the output Po, either as it is or with the value reduced. do. Further, the current command value output unit 12 outputs the torque current command value Iq* obtained from the torque command value T* as it is or by increasing the value based on the rotation speed ω and the output Po. do.

The subtraction unit 13 calculates the difference ΔId between the excitation current command value Id* output from the current command value output unit 12 and the excitation current Id output from the current conversion unit 9.

The subtraction unit 14 calculates the difference ΔIq between the torque current command value Iq* output from the current command value output unit 12 and the torque current Iq output from the current conversion unit 9.

The voltage command value calculation unit 15 calculates the excitation voltage command value Vd* and the torque voltage command value Vq* by PI control using the difference ΔId output from the subtraction unit 13 and the difference ΔIq output from the subtraction unit 14. . For example, the voltage command value calculation unit 15 calculates the excitation voltage command value Vd* by calculating the following equation 2, and calculates the torque voltage command value Vq* by calculating the following equation 3. In addition, Kp is the constant of the proportional term of PI control, Ki is the constant of the integral term of PI control, Lq is the torque inductance of induction machine M, Ld is the excitation inductance of induction machine M, and ω is the rotation speed calculation unit. 7, and Ψ is the induced voltage.

Excitation voltage command value Vd* = Kp x difference ΔId + ∫ (Ki x difference ΔId) - ωLqIq ... Formula 2
Torque voltage command value Vq*=Kp×difference ΔIq+∫(Ki×difference ΔIq)+ωLdId+ωΨ...Formula 3

The voltage command value converter 16 uses the position θ calculated by the position calculator 8 to convert the excitation voltage command value Vd* and the torque voltage command value Vq* into the U-phase voltage command value Vu* and the V-phase voltage command value. Vv* and W-phase voltage command value Vw*. For example, the voltage command value conversion unit 16 converts the excitation voltage command value Vd* and the torque voltage command value Vq* into the U-phase voltage command value Vu using the position θ and a conversion matrix for converting from two phases to three phases. *, V-phase voltage command value Vv*, and W-phase voltage command value Vw*.

That is, the control circuit 3 sets the torque command value T so that the rotation speed deviation Δω calculated from the rotation speed command value ω* input from the outside and the rotation speed ω based on the detected value of the rotation sensor En converges to zero. * is adjusted, and using the torque command value T*, an excitation current command value Id* and a torque current command value Iq* are obtained, and the operation of the inverter circuit 2 is controlled.

Here, FIG. 2(a) is a diagram showing an example of the excitation current command value Id* and the current flowing through the induction machine M when the rotation speed ω does not include an error. Note that the solid line shown on the d-axis of the d-axis, q-axis rotating coordinate system is the ideal excitation current command value Id* that does not include errors, and the broken line shown on the d-axis of the d-axis, q-axis rotating coordinate system is Let the exciting current flowing through the induction machine M be Id. Further, the torque current command value Iq* is set to zero.

When the rotation speed ω does not include an error, as shown in FIG. 2(a), there is no phase difference between the vector of the excitation current command value Id* and the vector of the excitation current Id, and the torque is unstable. No current flows through induction machine M. Therefore, unnecessary torque is not generated in the induction machine M, and the vehicle equipped with the induction machine M can continue to be stopped.

Moreover, FIG.2(b) and FIG.2(c) are figures which show an example of the exciting current command value Id* and the electric current which flows into the induction machine M when an error is included in rotation speed (omega). Note that the solid line shown on the γ-axis of the γ-axis, δ-axis rotational coordinate system, which has a different phase from the d-axis, q-axis rotational coordinate system, is the excitation current command value Id* that includes an error, and the d-axis, q-axis rotational coordinate system Let the broken line shown on the d-axis of the induction machine M be the exciting current Id flowing through the induction machine M, and let the dashed line shown on the q-axis of the d-axis q-axis rotating coordinate system be the torque current Iq flowing through the induction machine M. Further, the torque current command value Iq* is set to zero. Further, it is assumed that the excitation current command value Id* shown in FIG. 2(c) is smaller than the excitation current command value Id* shown in FIG. 2(b).

When the rotation speed ω includes an error, a phase difference occurs between the vector of the excitation current command value Id* and the vector of the excitation current Id, as shown in FIG. 2(b), and the excitation current command value Id The vector marked * is a composite vector of the excitation current Id vector and the torque current Iq vector. That is, if the rotational speed ω includes an error, an unstable torque current Iq will flow to the induction machine M even though the torque current command value Iq* is zero. Therefore, torque that is not normally generated is generated in the induction machine M, which drives the vehicle equipped with the induction machine M, which may give a sense of discomfort to the user driving the vehicle.

Therefore, in the current command value output unit 12 of the embodiment, when the rotational speed ω becomes relatively small (when the rotational speed ω tends to include an error), as shown in FIG. 2(c), the excitation current command The value Id* is made smaller than the excitation current command value Id* shown in FIG. 2(b). In this way, by reducing the excitation current command value Id*, which is a composite vector of the excitation current Id vector and the torque current Iq vector, the torque current Iq is decreased. As a result, even if a torque current Iq that does not originally occur due to an error in the rotational speed ω flows through the induction machine M, the torque current Iq can be reduced, so the torque generated in the induction machine M can be reduced. This makes it possible to suppress the sense of discomfort given to the user driving the vehicle.

<Example 1>
FIG. 3 is a flowchart showing the operation of the current command value output section 12 in the first embodiment.

First, when the rotation speed ω is greater than the rotation speed threshold ωth1 (first rotation speed threshold) (step S1: No), the current command value output unit 12 outputs the excitation current command value Id*1 as the excitation current command value Id*. (first excitation current command value) is output to the subtraction unit 13, and at the same time, torque current command value Iq*1 (first torque current command value) is output to the subtraction unit 14 as the torque current command value Iq* (step S2). Note that the excitation current command value Id*1 is the excitation current command value Id* determined from the torque command value T*. Further, the torque current command value Iq*1 is assumed to be the torque current command value Iq* obtained from the torque command value T*.

On the other hand, when the rotation speed ω is less than or equal to the rotation speed threshold ωth1 (step S1: Yes), the current command value output unit 12 outputs an excitation current command value Id*2 (second excitation current The command value) is output to the subtraction unit 13, and the torque current command value Iq*1 is output to the subtraction unit 14 (step S3).

As a result, when the rotation speed ω of the induction machine M is relatively small and the rotation speed ω tends to include an error, the vector of the excitation current command value Id* and the vector of the excitation current Id can be made relatively small. , the torque current Iq generated by the phase difference between the vector of the excitation current command value Id* and the vector of the excitation current Id can be reduced, and unnecessary torque generated in the induction machine M can be reduced.

<Example 2>
FIG. 4 is a flowchart showing the operation of the current command value output section 12 in the second embodiment.

First, when the rotation speed ω is larger than the rotation speed threshold ωth1 (step S1: No), the current command value output unit 12 outputs the excitation current command value Id*1 to the subtraction unit 13 as the excitation current command value Id*. The torque current command value Iq*1 is outputted to the subtraction unit 14 as the torque current command value Iq* (step S2).

On the other hand, when the rotation speed ω is less than or equal to the rotation speed threshold value ωth1 (step S1: Yes), the current command value output unit 12 outputs the excitation current command value Id*2 to the subtraction unit 13, and also outputs the torque current command value Iq* A torque current command value Iq*2 (second torque current command value) larger than 1 is output to the subtraction unit 14 (step S3').

Thereby, when it is desired to make the rotation speed ω of the induction machine M relatively small and the torque of the induction machine M relatively large, unnecessary torque generated in the induction machine M can be reduced.

<Example 3>
FIG. 5 is a flowchart showing the operation of the current command value output section 12 in the third embodiment.

First, when the rotation speed ω is larger than the rotation speed threshold value ωth1 (step S1: No), or when the rotation speed ω is less than or equal to the rotation speed threshold value ωth1 (step S1: Yes), When the output Po of the induction machine M is larger than the output threshold Poth1 (first output threshold) (step S4: No), the exciting current command value Id*1 is output to the subtraction unit 13 as the exciting current command value Id*. The torque current command value Iq*1 is outputted to the subtraction unit 14 as the torque current command value Iq* (step S2).

On the other hand, when the rotation speed ω is below the rotation speed threshold ωth1 (step S1: Yes), and when the output Po of the induction machine M is below the output threshold Poth1 (step S4: Yes), the excitation current command value Id*2 is output to the subtraction unit 13 as the excitation current command value Id*, and the torque current command value Iq*1 is output to the subtraction unit 14 as the torque current command value Iq* (step S3). .

Thereby, when the rotational speed ω and the output Po of the induction machine M are relatively small, unnecessary torque generated in the induction machine M can be reduced.

In addition, in step S3 of the flowchart shown in FIG. 5, the current command value output section 12 may be configured to output the excitation current command value Id*2 and the torque current command value Iq*2.

<Example 4>
FIG. 6 is a diagram for explaining the operation of the current command value output section 12 in the fourth embodiment.

The horizontal axis of the two-dimensional coordinates shown in FIG. 6(a) shows the rotation speed ω, the vertical axis shows the exciting current command value Id*, and the solid line shows the correspondence between the rotation speed ω and the exciting current command value Id* Map M1 is shown. It is assumed that the map M1 is stored in the storage unit 4 in advance. Note that in the map M1, the rotation speed threshold ωth2 (second rotation speed threshold) is set to a value smaller than the rotation speed threshold ωth1. Further, in the map M1, when the rotation speed ω calculated by the rotation speed calculation unit 7 is larger than the rotation speed threshold ωth1, the exciting current command value Id* corresponding to the rotation speed ω becomes the exciting current command value Id*1. shall be taken as a thing. Further, in the map M1, if the rotation speed ω calculated by the rotation speed calculation unit 7 is smaller than the rotation speed threshold ωth2, the exciting current command value Id* corresponding to the rotation speed ω becomes the exciting current command value Id*2. shall be taken as a thing. In addition, in the map M1, when the rotation speed ω calculated by the rotation speed calculation unit 7 is within the range from the rotation speed threshold ωth2 to the rotation speed threshold ωth1, the larger the rotation speed ω, the more the rotation speed ω corresponds to the rotation speed ω. It is assumed that the excitation current command value Id* increases within the range from the excitation current command value Id*2 to the excitation current command value Id*1. That is, in the map M1, when the rotation speed ω calculated by the rotation speed calculation unit 7 is within the range from the rotation speed threshold ωth2 to the rotation speed threshold ωth1, the excitation current command value Id* is in a proportional relationship with the rotation speed ω. shall become.

The horizontal axis of the two-dimensional coordinates shown in FIGS. 6(b) to 6(d) indicates the output Po, the vertical axis indicates the excitation current command value Id*, and the solid line indicates the relationship between the output Po and the excitation current command value Id*. A map M2 showing correspondence relationships is shown. Note that in the map M2 shown in FIGS. 6(c) and 6(d), the output threshold Poth2 (second output threshold) is set to a value smaller than the output threshold Poth1. In addition, the map M2 includes an excitation current command value Id* corresponding to an output Po smaller than the output threshold Poth2 and a range from the output threshold Poth2 to the output threshold Poth1 according to the excitation current command value Id* determined by the map M1. It is assumed that the excitation current command value Id* corresponding to the output Po changes.

The map M2 shown in FIG. 6(b) shows the output Po when the excitation current command value Id* determined by the map M1 is the excitation current command value Id*1 (when the rotation speed ω is larger than the rotation speed threshold ωth1). The correspondence relationship between and the excitation current command value Id* is shown. In the map M2 shown in FIG. 6(b), from the excitation current command value Id* corresponding to the output Po larger than the output threshold Poth1, the excitation current command value Id* corresponding to the output Po smaller than the output threshold Poth2, and the output threshold Poth2. It is assumed that the excitation current command value Id* corresponding to the output Po within the range up to the output threshold Poth1 becomes the excitation current command value Id*1. That is, in the map M2 shown in FIG. 6(b), all outputs Po correspond to the excitation current command value Id*1.

In addition, the map M2 shown in FIG. 6(c) shows the case where the excitation current command value Id* determined by the map M1 is the excitation current command value Id*2 (when the rotation speed ω is smaller than the rotation speed threshold ωth2). The correspondence relationship between the output Po and the excitation current command value Id* is shown. Furthermore, in the map M2 shown in FIG. 6(c), if the obtained output Po is larger than the output threshold Poth1, the excitation current command value Id* corresponding to the output Po will be the excitation current command value Id*1. do. Furthermore, in the map M2 shown in FIG. 6(c), if the obtained output Po is smaller than the output threshold Poth2, the excitation current command value Id* corresponding to the output Po will be the excitation current command value Id*2. do. Further, in the map M2 shown in FIG. 6(c), when the obtained output Po is within the range from the output threshold Poth2 to the output threshold Poth1, the larger the output Po, the more the excitation current command corresponding to the output Po. It is assumed that the value Id* increases within the range from the excitation current command value Id*2 to the excitation current command value Id*1. That is, in the map M2 shown in FIG. 6(c), if the obtained output Po is within the range from the output threshold Poth2 to the output threshold Poth1, the excitation current command value Id* is assumed to have a proportional relationship with the output Po. do.

Moreover, the map M2 shown in FIG. 6(d) is used when the excitation current command value Id* determined by the map M1 is within the range from the excitation current command value Id*2 to the excitation current command value Id*1 (rotation The correspondence relationship between the output Po and the excitation current command value Id* is shown when the number ω is within the range from the rotation speed threshold value ωth2 to the rotation speed threshold value ωth1). Furthermore, in the map M2 shown in FIG. 6(d), if the obtained output Po is larger than the output threshold Poth1, the excitation current command value Id* corresponding to the output Po will be the excitation current command value Id*1. do. Further, in the map M2 shown in FIG. 6(d), if the obtained output Po is smaller than the output threshold Poth2, the exciting current command value Id* corresponding to the output Po is the exciting current command value obtained from the map M1. The value is equal to the excitation current command value Id*4 within the range from Id*2 to the excitation current command value Id*1. Furthermore, in the map M2 shown in FIG. 6(d), when the obtained output Po is within the range from the output threshold Poth2 to the output threshold Poth1, the larger the output Po, the more the excitation current command corresponding to the output Po. It is assumed that the value Id* increases within the range from the excitation current command value Id*4 to the excitation current command value Id*1. That is, in the map M2 shown in FIG. 6(d), when the obtained output Po is within the range from the output threshold Poth2 to the output threshold Poth1, the excitation current command value Id* is assumed to have a proportional relationship with the output Po. do.

The current command value output unit 12 in the fourth embodiment uses any one of the map M1 shown in FIG. 6(a) and the maps M2 shown in FIGS. 6(b) to 6(d), It outputs the excitation current command value Id* and also outputs the torque current command value Iq*.

<Output example 1 of excitation current command value Id*>
For example, assume that the rotational speed ω is a rotational speed ωa that is larger than the rotational speed threshold value ωth1, and the output Po is an output Poa that is larger than the output threshold value Poth1.

First, the current command value output unit 12 refers to the map M1 shown in FIG. 6(a) to obtain the excitation current command value Id*1 corresponding to the rotation speed ωa.

Next, the current command value output unit 12 creates a map M2 shown in FIG. 6(b) based on the excitation current command value Id*1.

Then, the current command value output unit 12 refers to the map M2 shown in FIG. 6(b) to obtain an excitation current command value Id*1 (first excitation current command value) corresponding to the output Poa, and The command value Id*1 is output to the subtraction unit 13 as the excitation current command value Id*.

Similarly, when the rotation speed ω is a rotation speed ωa larger than the rotation speed threshold ωth1, and the output Po is the output Pob smaller than the output threshold Poth2, or when the rotation speed ω is a rotation speed ωa larger than the rotation speed threshold ωth1. Even in the case where the output Po is the output Poc within the range from the output threshold Poth2 to the output threshold Poth1, the current command value output unit 12 converts the excitation current command value Id*1 into the excitation current command value. It is output to the subtraction unit 13 as Id*.

That is, when the rotation speed ω is larger than the rotation speed threshold ωth1, the current command value output unit 12 in the fourth embodiment outputs the excitation current determined by referring to the map M2 shown in FIG. 6(b), as shown in FIG. The command value Id*1 is output to the subtraction unit 13 as the excitation current command value Id*.

<Output example 2 of excitation current command value Id*>
For example, assume that the rotational speed ω is a rotational speed ωb smaller than the rotational speed threshold ωth2, and the output Po is an output Poa larger than the output threshold Poth1.

First, the current command value output unit 12 refers to the map M1 shown in FIG. 6(a) to obtain the excitation current command value Id*2 corresponding to the rotation speed ωb.

Next, the current command value output unit 12 creates a map M2 shown in FIG. 6(c) based on the excitation current command value Id*2.

Then, the current command value output unit 12 refers to the map M2 shown in FIG. It is output to the subtraction unit 13 as the command value Id*.

That is, when the rotation speed ω is smaller than the rotation speed threshold ωth2 and the output Po is larger than the output threshold Poth1, the current command value output unit 12 in the fourth embodiment outputs the map shown in FIG. 6(c) as shown in FIG. The excitation current command value Id*1 obtained with reference to M2 is output to the subtraction unit 13 as the excitation current command value Id*.

<Output example 3 of excitation current command value Id*>
For example, assume that the rotational speed ω is a rotational speed ωc within the range from the rotational speed threshold ωth2 to the rotational speed threshold ωth1, and the output Po is an output Poa larger than the output threshold Poth1.

First, the current command value output unit 12 refers to the map M1 shown in FIG. 6(a) to obtain the excitation current command value Id*4 corresponding to the rotational speed ωc.

Next, the current command value output unit 12 creates a map M2 shown in FIG. 6(d) based on the excitation current command value Id*4.

Then, the current command value output unit 12 refers to the map M2 shown in FIG. It is output to the subtraction unit 13 as the command value Id*.

That is, when the rotation speed ω is within the range from the rotation speed threshold ωth2 to the rotation speed threshold ωth1, and the output Po is larger than the output threshold Poth1, the current command value output unit 12 in the fourth embodiment , the excitation current command value Id*1 obtained with reference to the map M2 shown in FIG. 6(d) is output to the subtraction unit 13 as the excitation current command value Id*.

<Output example 4 of excitation current command value Id*'>
For example, assume that the rotational speed ω is a rotational speed ωb smaller than the rotational speed threshold ωth2, and the output Po is an output Pob smaller than the output threshold Poth2.

First, the current command value output unit 12 refers to the map M1 shown in FIG. 6(a) to obtain the excitation current command value Id*2 corresponding to the rotation speed ωb.

Next, the current command value output unit 12 creates a map M2 shown in FIG. 6(c) based on the excitation current command value Id*2.

Then, the current command value output unit 12 refers to the map M2 shown in FIG. It is output to the subtraction unit 13 as the command value Id*.

That is, when the rotation speed ω is smaller than the rotation speed threshold ωth2 and the output Po is smaller than the output threshold Poth2, the current command value output unit 12 in the fourth embodiment outputs the map shown in FIG. 6(c) as shown in FIG. The excitation current command value Id*2 obtained with reference to M2 is output to the subtraction unit 13 as the excitation current command value Id*.

<Example 5 of output of excitation current command value Id*'>
For example, assume that the rotational speed ω is a rotational speed ωb smaller than the rotational speed threshold ωth2, and the output Po is an output Poc within the range from the output threshold Poth2 to the output threshold Poth1.

First, the current command value output unit 12 refers to the map M1 shown in FIG. 6(a) to obtain the excitation current command value Id*2 corresponding to the rotation speed ωb.

Next, the current command value output unit 12 creates a map M2 shown in FIG. 6(c) based on the excitation current command value Id*2.

Then, the current command value output unit 12 refers to the map M2 shown in FIG. 6(c) to obtain an excitation current command value Id*3 (third excitation current command value) corresponding to the output Poc, The command value Id*3 is output to the subtraction unit 13 as the excitation current command value Id*.

That is, the current command value output unit 12 in the fourth embodiment, as shown in FIG. The excitation current command value Id*3 obtained with reference to the map M2 shown in FIG. 6(c) is output to the subtraction unit 13 as the excitation current command value Id*.

<Output example 6 of excitation current command value Id*'>
For example, assume that the rotational speed ω is a rotational speed ωc within the range from the rotational speed threshold value ωth2 to the rotational speed threshold value ωth1, and the output Po is an output Pob smaller than the output threshold value Poth2.

First, the current command value output unit 12 refers to the map M1 shown in FIG. 6(a) to obtain an excitation current command value Id*4 (fourth excitation current command value) corresponding to the rotational speed ωc.

Next, the current command value output unit 12 creates a map M2 shown in FIG. 6(d) based on the excitation current command value Id*4.

Then, the current command value output unit 12 refers to the map M2 shown in FIG. It is output to the subtraction unit 13 as the command value Id*.

That is, when the rotation speed ω is within the range from the rotation speed threshold ωth2 to the rotation speed threshold ωth1, and the output Po is smaller than the output threshold Poth2, the current command value output unit 12 in the fourth embodiment , the excitation current command value Id*4 obtained with reference to the map M2 shown in FIG. 6(d) is outputted to the subtraction unit 13 as the excitation current command value Id*.

<Example 7 of output of excitation current command value Id*'>
For example, assume that the rotation speed ω is the rotation speed ωc within the range from the rotation speed threshold ωth2 to the rotation speed threshold ωth1, and the output Po is the output Poc within the range from the output threshold Poth2 to the output threshold Poth1. do.

First, the current command value output unit 12 refers to the map M1 shown in FIG. 6(a) to obtain the excitation current command value Id*4 corresponding to the rotational speed ωc.

Next, the current command value output unit 12 creates a map M2 shown in FIG. 6(d) based on the excitation current command value Id*4.

Then, the current command value output unit 12 refers to the map M2 shown in FIG. 6(d) to obtain an excitation current command value Id*5 (fifth excitation current command value) corresponding to the output Poc, and The command value Id*5 is output to the subtraction unit 13 as the excitation current command value Id*. Note that excitation current command value Id*2<excitation current command value Id*4<excitation current command value Id*5<excitation current command value Id*1.

That is, in the current command value output unit 12 in the fourth embodiment, the rotation speed ω is within the range from the rotation speed threshold ωth2 to the rotation speed threshold ωth1, and the output Po is within the range from the output threshold Poth2 to the output threshold Poth1. In this case, as shown in FIG. 7, the excitation current command value Id*5 obtained with reference to the map M2 shown in FIG. 6(d) is output to the subtraction unit 13 as the excitation current command value Id*.

In this way, by using the map M1 and the map M2, the exciting current command value Id*3, the exciting current command value Id*3, Excitation current command value Id*4 or excitation current command value Id*5 can be determined.

Therefore, when the rotational speed ω or the output Po gradually decreases, the excitation current command value Id* can also gradually decrease.

As a result, when the rotational speed ω and output Po of the induction machine M are relatively small, it is possible to suppress the excitation current command value Id* from decreasing sharply, so that the excitation current command value can be prevented from decreasing sharply. This can alleviate the discomfort that the user feels.

In the fourth embodiment, the current command value output unit 12 is configured to output the torque current command value Iq*2 instead of the torque current command value Iq*1 when the rotation speed ω is less than or equal to the rotation speed threshold value ωth1. You may.

Furthermore, the present invention is not limited to the above-described embodiments, and various improvements and changes can be made without departing from the gist of the present invention.

1 Control device 2 Inverter circuit 3 Control circuit 4 Storage section 5 Drive circuit 6 Arithmetic section 7 Rotation speed calculation section 8 Position calculation section 9 Current conversion section 10 Subtraction section 11 Torque command value calculation section 12 Current command value output section 13 Subtraction section 14 Subtraction section 15 Voltage command value calculation section 16 Voltage command value conversion section P Power supply C Capacitor Se1 Current sensor Se2 Current sensor En Rotation sensor

Claims (4)

An inverter circuit that drives an induction machine,
The torque command value is adjusted so that the rotation speed deviation calculated from the rotation speed command value input from the outside and the rotation speed based on the detection value of the rotation sensor converges to zero, and the excitation is performed using the torque command value. a control circuit that acquires a current command value and a torque current command value to control the operation of the inverter circuit;
Equipped with
The control circuit includes:
When the rotation speed of the induction machine is larger than a first rotation speed threshold, the excitation current command value is set as a first excitation current command value, and the torque current command value is set as a first torque current command value to control the operation of the inverter circuit. control,
When the rotation speed is less than or equal to the first rotation speed threshold, a second excitation current command value smaller than the first excitation current command value and a second excitation current command value larger than the first torque current command value or the first torque current command value are selected. 2. A control device for an induction machine, characterized in that the operation of the inverter circuit is controlled based on a torque current command value. An inverter circuit that drives an induction machine,
The torque command value is adjusted so that the rotation speed deviation calculated from the rotation speed command value input from the outside and the rotation speed based on the detection value of the rotation sensor converges to zero, and the excitation is performed using the torque command value. a control circuit that acquires a current command value and a torque current command value to control the operation of the inverter circuit;
Equipped with
The control circuit includes:
If the rotation speed is larger than the first rotation speed threshold, or if the rotation speed is less than or equal to the first rotation speed threshold and the output of the induction machine is larger than the first output threshold, the excitation current command value is set to the first rotation speed threshold. 1 excitation current command value and the torque current command value as a first torque current command value to control the operation of the inverter circuit;
When the rotation speed is less than or equal to the first rotation speed threshold and the output of the induction machine is less than or equal to the first output threshold, a second excitation current command value smaller than the first excitation current command value and the first torque A control device for an induction machine, characterized in that the operation of the inverter circuit is controlled by a current command value. An inverter circuit that drives an induction machine,
The torque command value is adjusted so that the rotation speed deviation calculated from the rotation speed command value input from the outside and the rotation speed based on the detection value of the rotation sensor converges to zero, and the excitation is performed using the torque command value. a control circuit that acquires a current command value and a torque current command value to control the operation of the inverter circuit;
Equipped with
The control circuit includes:
If the rotation speed is larger than the first rotation speed threshold, or if the rotation speed is less than or equal to the first rotation speed threshold and the output of the induction machine is larger than the first output threshold, the excitation current command value is set to the first rotation speed threshold. 1 excitation current command value and the torque current command value as a first torque current command value to control the operation of the inverter circuit;
If the rotation speed is smaller than a second rotation speed threshold, which is smaller than the first rotation speed threshold, and the output of the induction machine is smaller than a second output threshold, which is smaller than the first output threshold, it is smaller than the first excitation current command value. controlling the operation of the inverter circuit according to the second excitation current command value and the first torque current command value;
When the rotation speed is smaller than the second rotation speed threshold and the output of the induction machine is within the range from the second output threshold to the first output threshold, the first excitation is changed from the second excitation current command value. A control device for an induction machine, characterized in that the operation of the inverter circuit is controlled by a third excitation current command value and the first torque current command value corresponding to the output of the induction machine within a range up to a current command value. The induction machine control device according to claim 3,
The control circuit includes:
When the rotation speed is within the range from the second rotation speed threshold to the first rotation speed threshold and the output of the induction machine is smaller than the second output threshold, controlling the operation of the inverter circuit according to the fourth excitation current command value and the first torque current command value corresponding to the rotation speed within a range up to the excitation current command value;
When the rotation speed is within the range from the second rotation speed threshold to the first rotation speed threshold, and the output of the induction machine is within the range from the second output threshold to the first output threshold, The operation of the inverter circuit is controlled by a fifth excitation current command value and the first torque current command value corresponding to an output of the induction machine within a range from a fourth excitation current command value to the first excitation current command value. An induction machine control device characterized by:

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