JP2016082709A - Controller for induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress motor torque variations caused by a temperature change of a rotor.SOLUTION: A controller for an induction motor converts a current to flow to a stator of the induction motor into a magnetic flux current and a torque current on a γδ-axis rotation coordinate system synchronized to a power supply angular frequency that is obtained by adding a slip angular frequency to an electric angular frequency of the induction motor and performs vector control for independently controlling the magnetic flux current and the torque current in such a manner that a rotor magnetic flux is matched to a γ-axis. The controller for the induction motor calculates an axial deviation index indicating a deviation of the rotor magnetic flux relative to the γ-axis and corrects the slip angular frequency in such a manner that the calculated axial deviation index is matched with a reference axial deviation index at the time when a temperature of the rotor is in a nominal state.SELECTED DRAWING: Figure 7

Description

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

Magnetic flux current iγ _s and torque current iδ obtained by converting the three-phase alternating current flowing through the stator of the induction motor into an orthogonal γδ-axis rotational coordinate system synchronized with the power source angular frequency ω (= motor electrical angular frequency ω _re + slip angular frequency ω _se ) Vector control for induction motors that controls motor torque by adjusting _s is known.

  The induction motor characteristic in the orthogonal γδ axis rotation coordinate system is represented by the state equation (fourth order) of Equation (1). The motor torque Te is expressed by the following equation (2).

In equations (1) and (2), R is a resistance value, L is a self-inductance, M is a mutual inductance, and σ is a leakage coefficient (= 1−M ² / L _s L _r ). The subscript s means the stator side, r means the rotor side, γ means the γ-axis component, δ means the δ-axis component, and s means the Laplace operator.

Here, by setting the slip angular frequency ω _se so that the rotor magnetic flux coincides with the γ-axis (φδ _r = 0), the state equation of the equation (1) becomes the third-order state equation represented by the equation (3). Vector control is established. Further, the motor torque Te is also simplified and expressed by the following equation (4).

  However, when the value of the rotor resistance changes due to the temperature change of the rotor, the slip angular frequency at which vector control is established also changes, causing an axial shift in which the rotor magnetic flux does not coincide with the γ axis, and the control performance of the motor deteriorates.

On the other hand, in Non-Patent Document 1, the δ-axis component φδ _r of the rotor magnetic flux that should be 0 when the vector control is established is obtained from an equation, and the obtained δ-axis component φδ _r of the rotor magnetic flux is obtained. It is disclosed that the slip angular frequency is corrected so that becomes zero.

Naoki Yamamura, Masakatsu Ogami, Joe Tsunehiro, “A Method of Secondary Resistance Correction in Vector Control of Induction Motors”, IEEJ Transactions, Vol. 111No. 7, 1991

However, in reality, even when the rotor temperature is in a nominal state, shaft misalignment may occur due to factors other than changes in the rotor temperature, such as voltage control error, current measurement error, and model constant misalignment. In this case, the δ-axis component Faideruta _r of the rotor flux to correct the slip angular frequency as a 0, will be subjected to extra compensation, an error occurs motor torque deviates from the target value.

  An object of this invention is to provide the technique which suppresses the motor torque fluctuation | variation resulting from the temperature change of a rotor.

  The induction motor control device according to the present invention is a magnetic flux current on the γδ axis rotation coordinate system in which the current flowing through the stator of the induction motor is synchronized with the power angular frequency obtained by adding the slip angular frequency to the electrical angular frequency of the induction motor. Then, vector control is performed to control the magnetic flux current and the torque current independently so that the rotor magnetic flux is made to coincide with the γ axis. In this induction motor control apparatus, an axis deviation index indicating the deviation of the rotor magnetic flux with respect to the γ-axis is obtained, and the obtained axis deviation index matches the reference axis deviation index when the rotor temperature is in the nominal state. Correct the slip angular frequency.

  According to the present invention, an axis deviation index indicating the deviation of the rotor magnetic flux with respect to the γ axis is obtained, and the slip angular frequency is determined so that the obtained axis deviation index coincides with the reference axis deviation index when the rotor temperature is in the nominal state. Therefore, even when the rotor temperature changes, the motor torque can be made to coincide with the motor torque when the rotor temperature is in the nominal state, and the motor torque fluctuation caused by the rotor temperature change can be suppressed.

FIG. 1 is a block diagram illustrating a configuration of a control device for an induction motor according to a first embodiment. FIG. 2 is a diagram illustrating the relationship between the rotor magnetic flux and the rotor current when no shaft misalignment occurs. FIG. 3 is a diagram illustrating a relationship between the rotor magnetic flux and the rotor current when the shaft misalignment occurs. FIG. 4 is a diagram showing characteristics due to the difference in rotor temperature. The upper diagram shows the relationship between the slip angular frequency ω _se and the axis deviation index φδ _r, and the lower diagram shows the relationship between the slip angular frequency ω _se and the motor torque T. Showing the relationship. FIG. 5 is a diagram for explaining that torque fluctuation occurs in the conventional control method when a shaft deviation occurs when the rotor temperature is in a nominal state. FIG. 6 is a diagram for explaining slip angular frequency correction processing performed by the correction value calculator in the present embodiment when the shaft temperature is shifted while the rotor temperature is in the nominal state. FIG. 7 is a block diagram showing a detailed configuration of the correction value calculator. FIG. 8 is a block diagram showing another configuration example of the correction value calculator. FIG. 9 is a block diagram showing another configuration example of the correction value calculator. FIG. 10 is a diagram showing a detailed configuration of the correction value calculator in the induction motor control apparatus according to the second embodiment. FIG. 11 is a diagram showing that the amount of torque fluctuation changes depending on the magnitude of the axis deviation index H0. FIG. 12 is a diagram showing a detailed configuration of the correction value calculator in the induction motor control apparatus according to the third embodiment. FIG. 13 is a diagram showing that the axis deviation index H0 in which the rotor temperature is in the nominal state varies depending on the operating point of the induction motor 1. FIG. FIG. 14 shows a configuration example of a correction value calculator configured to obtain an axis deviation index H0 in which the rotor temperature is in a nominal state based on the rotation speed N of the induction motor 1, the torque command value T ^* , and the DC power supply voltage Vdc. FIG. FIG. 15 is a block diagram showing a configuration example of a correction value calculator having a configuration for obtaining an axis deviation index H0 corresponding to the operating point of the induction motor 1 and obtaining an offset value corresponding to the operating point of the induction motor. .

<First Embodiment>
FIG. 1 is a block diagram illustrating a configuration of a control device for an induction motor according to a first embodiment. This induction motor control device is applied to, for example, an electric vehicle. However, the application destination is not limited to an electric vehicle, and can be applied to, for example, a hybrid vehicle or a system other than a vehicle.

  An induction motor (induction motor) 1 is a three-phase AC induction motor. When the induction motor control device is applied to an electric vehicle, the induction motor 1 serves as a drive source for the vehicle.

The PWM converter 6 is based on the three-phase voltage command values V _u ^* , V _v ^* , V _w ^* , and PWM_Duty of a switching element (IGBT or the like) of the three-phase voltage type inverter 3 (hereinafter simply referred to as the inverter 3). Drive signals D _uu ^* , D _ul ^* , D _vu ^* , D _vl ^* , D _wu ^* , and D _wl ^* are generated.

The inverter 3 converts the DC voltage of the DC power supply 2 into AC voltages V _u , V _v , V _w based on the PWM_Duty drive signal generated by the PWM converter 6 and supplies the AC voltage to the induction motor 1. The DC power source 2 is, for example, a stacked lithium ion battery.

The current sensor 4 detects at least two-phase currents (for example, a U-phase current i _u and a V-phase current i _v ) among the three-phase AC currents supplied from the inverter 3 to the induction motor 1. The detected two-phase currents i _u and _iv are converted into digital signals i _us and i _vs by the AD converter 7 and input to the three-phase / γ-δ AC coordinate converter 11. When the current sensor 4 is attached to only two phases, the remaining one-phase current i _ws can be obtained by the following equation (5).

The magnetic pole position detector 5 outputs A-phase B-phase Z-phase pulses corresponding to the rotor position (angle) of the induction motor 1, and the rotor mechanical angle θ _rm is obtained through the pulse counter 8. The angular velocity calculator 9 receives the rotor mechanical angle θ _rm, and from the rate of change over time, the rotor mechanical angular velocity ω _rm and the rotor electrical angular velocity ω _rm obtained by multiplying the rotor mechanical angular velocity ω _rm by the motor pole pair number p. ask for _re .

The γ-δ / 3-phase AC coordinate converter 12 performs conversion from an orthogonal two-axis DC coordinate system (γ-δ axis coordinate system) rotating at a power source angular velocity ω described later to a three-phase AC coordinate system (UVW axis). . Specifically, the γ-axis voltage command value (magnetic flux voltage command value) Vγ _s ^* , the δ-axis voltage command value (torque voltage command value) Vδ _s ^* and the power source angular velocity ω are integrated by the power source angle calculator 10. The input power supply angle θ is input, and coordinate conversion processing according to the following equation (6) is performed to calculate and output voltage command values V _u ^* , V _v ^* , and V _w ^* for each UVW phase. However, θ ′ in the equation (6) is the same as θ.

The three-phase / γ-δ AC coordinate converter 11 performs conversion from a three-phase AC coordinate system (UVW axis) to an orthogonal two-axis DC coordinate system (γ-δ axis coordinate system). Specifically, a U-phase current i _us , a V-phase current i _vs , a W-phase current i _ws, and a power supply angle θ obtained by integrating the power supply angular velocity ω are input. ) I γ _s and δ-axis current (torque current) i δ _s are calculated.

The current command value calculator 13 inputs the target motor torque T ^* , the motor rotation speed (mechanical angular velocity ω _rm ), and the DC voltage V _dc of the DC power supply 2, and the γ-axis current command value (flux current command value) iγ _s ^{* *} , Δ-axis current command value (torque current command value) iδ _s ^** is calculated. The γ-axis current command value iγ _s ^** and the δ-axis current command value iδ _s ^** are respectively the target motor torque T ^* , the motor rotation speed (mechanical angular velocity ω _rm ), the DC voltage V _dc, and the γ-axis current command value iγ. _s ^**, allowed to advance in a memory to store map data that defines the relationship between the δ-axis current value i? _s ^**, can be determined by referring to the map data.

The slip angular frequency controller 14 receives the γ-axis current (magnetic flux current) iγ _s and the δ-axis current (torque current) iδ _s as input, and calculates the slip angular velocity ω _se from the following equation (8). By calculating the slip angular velocity ω _se as shown in equation (8), the rotor magnetic flux coincides with the γ-axis direction, and the equation of state of equation (1) is the third-order equation of equation shown in equation (3) above. Vector control is established. Further, the motor torque Te is also simplified and expressed by the above equation (4). Here, R _r and L _r are parameters of the induction motor 1 and indicate rotor resistance and rotor self-inductance, respectively.

The slip angular frequency controller 14 also corrects the slip angular velocity ω _se calculated by the equation (8) based on the correction value calculated by the correction value calculator 18 described later. A value obtained by adding the corrected slip angular velocity ω _se to the rotor electrical angular velocity ω _re is defined as a power source angular velocity ω. By performing this slip angular frequency control, the induction motor torque is proportional to the product of the γ-axis current (magnetic flux current) iγ _s and the δ-axis current (torque current) iδ _s .

Here, the correction of the slip angular velocity ω _se, is the meaning of the correction of the size of the slip angular velocity ω _se. Since the physical quantity corresponding to the magnitude of the slip angular velocity which is a vector is the slip angular frequency, “slip angular velocity correction” can be rephrased as “slip angular frequency correction”. Further, when it is not necessary to consider the direction of the vector, “slip angular velocity” and “slip angular frequency” are synonymous.

The magnetic flux current controller 15 follows the γ-axis current command value (flux current command value) iγ _s ^{* so} that the measured γ-axis current (flux current) iγ _s follows the γ-axis with a desired response without a steady deviation. The voltage command value vγ _s ^** is calculated. The torque current controller 16 is configured to cause the measured δ-axis current (torque current) iδ _s to follow the δ-axis current command value (torque current command value) iδ _s ^* with a desired response without a steady deviation. The voltage command value vδ _s ^** is calculated. Normally, if the control that cancels the interference voltage between the γ-δ orthogonal coordinate axes functions ideally, it becomes a simple control target characteristic with one input and one output, and therefore it can be realized with a simple PI feedback compensator. A value _obtained by adding the non-interference voltage Vγ _s ^* _{_dcpl} to the voltage command value vγ _s ^** which is the output of the magnetic flux current controller 15 is used as a γ-axis voltage command value (flux voltage command value) Vγ _s ^* , and the torque current controller A value _obtained by adding the non-interference voltage Vδ _s ^* _{_dcpl} to the voltage command value vδ _s ^** which is an output of 16 is defined as a δ-axis voltage command value (torque voltage command value) Vδ _s ^* . A method of calculating the non-interference voltages Vγ _s ^* _{_dcpl} and Vδ _s ^* _{_dcpl} will be described later.

The non-interference controller 17 inputs the measured γ-axis current (magnetic flux current) iγ _s , δ-axis current (torque current) iδ _s , and power supply angular frequency ω, and cancels the interference voltage between γ-δ orthogonal coordinate axes. non-interference voltage _{Vγ s} ^* _ dcpl necessary to calculate the _{Vδ s} ^* _ dcpl from the following equation (9).

  However, τ in the equation (9) is a time constant of the rotor magnetic flux, and is a very large value compared to the time constant of the current response. S is a Laplace operator.

The correction value calculator 18 measures the measured γ-axis current (flux current) iγ _s and δ-axis current (torque current) iδ _s , γ-axis voltage command value (flux voltage command value) Vγ _s ^*, and δ-axis voltage command. A value (torque voltage command value) Vδ _s ^* is inputted to obtain an axis deviation index H representing a deviation of the rotor magnetic flux with respect to the γ axis, and the obtained axis deviation index H is used as an axis deviation when the rotor temperature is in a nominal state. A correction value for matching with the index (reference axis deviation index) H0 is obtained. This correction value is for correcting the slip angular velocity ω _se .

In order to obtain the correction value, instead of the γ-axis voltage command value (magnetic flux voltage command value) Vγ _s ^* and the δ-axis voltage command value (torque voltage command value) Vδ _s ^* , the γ-axis voltage (magnetic flux voltage) Vγ Measurement values of _s and δ-axis voltage (torque voltage) Vδ _s may be input and used.

FIG. 2 is a diagram illustrating the relationship between the rotor magnetic flux and the rotor current when no shaft misalignment occurs, and FIG. 3 illustrates the relationship between the rotor magnetic flux and the rotor current when the shaft misalignment occurs. FIG. As shown in FIG. 2, when the axial misalignment is not generated, the direction of the rotor flux coincides with γ-axis, [delta] axis component Faideruta _r of the rotor flux is zero.

As described above, the correction value calculator 18 obtains a correction value for making the obtained axis deviation index H coincide with the axis deviation index H0 when the rotor temperature is in the nominal state, and the slip angular frequency controller 14 The slip angular velocity ω _se is corrected based on the correction value. Prior to describing details of the slip angular velocity (slip angular frequency) correction processing performed in the present embodiment, a conventional control method will be described with reference to FIGS. 4 and 5. 4 and 5, the δ-axis component φδ _r of the rotor magnetic flux is used as an axis deviation index representing the axis deviation, and the axis deviation is 0 when φδ _r = 0.

FIG. 4 shows the characteristics due to the difference in rotor temperature. The upper diagram shows the relationship between the slip angular velocity ω _se and the axis deviation index φδ _r, and the lower diagram shows the relationship between the slip angular velocity ω _se and the motor torque T. ing. In the upper and lower diagrams, lines indicating the characteristics when the rotor temperature is in the nominal state, the characteristics when the rotor temperature is higher than the nominal state, and the characteristics when the rotor temperature is lower than the nominal state are drawn. In FIG. 4, it is assumed that no shaft misalignment occurs (φδ _r = 0) when the rotor temperature is in the nominal state.

When the rotor temperature is in the nominal state, it operates at the operating point 1 in the figure. However, when the rotor temperature rises, the operating point changes from the operating point 1 to the operating point 2, whereby the axis deviation index φδ _r Deviates from 0, and the operating point of the motor torque changes from the operating point 1 to the operating point 2. In the conventional control method, by correcting the slip angular frequency ω _se so that the estimated axis deviation index φδ _r becomes 0, the operating point changes from the operating point 2 to the operating point 3 of the slip angular velocity at which vector control is established. The same motor torque as that of the operating point 1 can be output.

  However, when the rotor temperature is in the nominal state, there should be no shaft misalignment, but in reality, shaft misalignment may occur due to factors such as voltage control error, current measurement error, model constant misalignment, etc. is there.

FIG. 5 is a diagram for explaining that torque fluctuation occurs in the conventional control method when a shaft deviation occurs when the rotor temperature is in a nominal state. Also in FIG. 5, the upper diagram shows the relationship between the slip angular velocity ω _se and the axis deviation index φδ _r, and the lower diagram shows the relationship between the slip angular velocity ω _se and the motor torque T. In the above figure, the solid line is a line indicating the characteristic when no axial deviation occurs, and the wavy line is a line indicating the characteristic when the axial deviation occurs due to factors other than the rotor temperature fluctuation.

With respect to the assumed operating point 1, the actual operating point when the axis is shifted due to factors other than the rotor temperature fluctuation is the operating point 1. In the conventional control method, since the slip angular velocity ω _se is corrected so that the estimated axis deviation index φδ _r becomes zero, the operating point is the corrected operating point 2, but as shown in the figure below, the torque fluctuation Will occur.

  Next, details of the slip angular velocity correction process performed by the induction motor control apparatus according to the present embodiment will be described with reference to FIGS. 6 and 7.

The correction value calculator 18 measures the measured γ-axis current (flux current) iγ _s and δ-axis current (torque current) iδ _s , γ-axis voltage command value (flux voltage command value) Vγ _s ^*, and δ-axis voltage command. A value (torque voltage command value) Vδ _s ^* is input to obtain an axis deviation index H that represents the deviation of the rotor magnetic flux with respect to the γ axis. The axis deviation index H is not particularly limited as long as it is an index that changes due to fluctuations in the rotor temperature. For example, the reactive power Q shown in the following equation (10) or the reactive power Q shown in the following equation (11) is divided by the power source angular velocity ω. Values can be used.

FIG. 6 is a diagram for explaining a slip angular velocity (slip angular frequency) correction process performed by the induction motor control apparatus according to the present embodiment when a shaft deviation occurs when the rotor temperature is in a nominal state. In FIG. 6, the upper diagram shows the relationship between the slip angular velocity ω _se and the axis deviation index H, and the lower diagram shows the relationship between the slip angular velocity ω _se and the motor torque T. In the upper and lower graphs, the rotor temperature is in a nominal state characteristic (L1), the rotor temperature is higher than the nominal state (L2), and the rotor temperature is lower than the nominal state (L2). Is drawn. In the above figure, solid lines (L1 to L3) are lines indicating characteristics when no axis deviation occurs, and wavy lines (L1a to L3a) are cases where axis deviation occurs due to factors other than rotor temperature fluctuations. It is a line which shows the characteristic.

In this embodiment, the axis deviation index H0 in which the rotor temperature is in the nominal state is obtained in advance. For example, when the reactive power Q shown in Expression (10) is used as the axis deviation index H, the reactive power Q when the rotor temperature is in the nominal state is obtained as the axis deviation index H0. Referring to FIG. 6, the assumed operating point when the rotor temperature is in the nominal state is a point where the axis deviation index H is 0 on the line L1, but the actual operating point is caused by a factor other than the temperature fluctuation of the rotor. On the line L1a indicating the characteristic when the above _occurs , the point becomes the same slip angular velocity _ωse1 , and the axis deviation index H0 of this point is obtained in advance.

When the rotor temperature is increased from the nominal temperature, the operating point changes to the point of the slip angular velocity ω _se1 on the line L2a. The control device for the induction motor according to the present embodiment corrects the slip angular velocity so that the axis deviation index H matches the axis deviation index H0. Referring to FIG. 6, the slip angular velocity ω _se is corrected so as to be the slip angular velocity ω _se2 at the intersection of the line L2a and the line L5 indicating the axis deviation index H0. Thereby, as shown in the lower diagram of FIG. 6, even when the rotor temperature becomes high, the motor torque T does not fluctuate.

When the rotor temperature is _lowered from the nominal state temperature, the operating point changes to the point of the slip angular velocity ω _se1 on the line L3a. The control device for the induction motor according to the present embodiment corrects the slip angular velocity so that the axis deviation index H matches the axis deviation index H0. Referring to FIG. 6, the slip angular velocity ω _se is corrected so that the slip angular frequency ω _se3 at the intersection of the line L3a and the line L5 indicating the axis deviation index H0 is obtained. Thereby, as shown in the lower diagram of FIG. 6, even when the rotor temperature becomes low, the motor torque T does not fluctuate.

  FIG. 7 is a block diagram showing a detailed configuration of the correction value calculator 18. The correction value calculator 18 includes an axis deviation index calculator 181, a H0 storage 182, and a PI controller 183.

The axis deviation index calculator 181 includes the measured γ-axis current (flux current) iγ _s and δ-axis current (torque current) iδ _s , γ-axis voltage command value (flux voltage command value) Vγ _s ^*, and δ-axis voltage. A command value (torque voltage command value) Vδ _s ^* is input, and an axis deviation index H is calculated.

  The H0 storage 182 stores an axis deviation index H0 that is obtained in advance and that the rotor temperature is in a nominal state.

The PI controller 183 determines the axis deviation index H based on the deviation ΔH between the axis deviation index H calculated by the axis deviation index calculator 181 and the axis deviation index H0 stored in the H0 storage unit 182. A correction value Δω _se for matching with the index H0 is calculated. This correction value Δω _se is a correction value for correcting the slip angular velocity ω _se .

The slip angular frequency controller 14 calculates the corrected slip angular frequency ω _se from the following equation (12).

  FIG. 8 is a block diagram showing another configuration example of the correction value calculator 18. 7 is different from the block diagram shown in FIG. 7 in that the PI controller 183 in FIG. 7 is replaced with a PI controller 183A.

The PI controller 183A determines the axis deviation index H based on the deviation ΔH between the axis deviation index H calculated by the axis deviation index calculator 181 and the axis deviation index H0 stored in the H0 storage 182. A correction value ΔR _r for matching with the index H0 is calculated. This correction value ΔR _r is a correction value for correcting the rotor resistance R that varies depending on the rotor temperature.

In this case, the slip angular frequency controller 14 calculates the corrected slip angular velocity ω _se from the following equation (13).

  FIG. 9 is a block diagram illustrating another configuration example of the correction value calculator 18. 7 is different from the block diagram shown in FIG. 7 in that the PI controller 183 in FIG. 7 is replaced with a PI controller 183B.

The PI controller 183B determines the axis deviation index H based on the deviation ΔH between the axis deviation index H calculated by the axis deviation index calculator 181 and the axis deviation index H0 stored in the H0 storage unit 182. A correction value ΔR _r / L _r for matching with the index H0 is calculated. The correction value ΔR _r / L _r is a correction value for correcting a constant used when the slip angular frequency controller 14 calculates the slip angular velocity ω _se .

In this case, the slip angular frequency controller 14 calculates the corrected slip angular velocity ω _se from the following equation (14).

  As described above, the control device for the induction motor according to the first embodiment is configured such that the current flowing through the stator of the induction motor is synchronized with the power angular frequency obtained by adding the slip angular frequency to the electrical angular frequency of the induction motor. In an induction motor control apparatus that performs vector control that converts magnetic flux current and torque current on the system to independently control the magnetic flux current and torque current so that the rotor magnetic flux matches the γ-axis, the rotor magnetic flux with respect to the γ-axis An axial deviation index H indicating the deviation is obtained, and the slip angular frequency is corrected so that the obtained axial deviation index H matches the axial deviation index H0 when the temperature of the rotor is in the nominal state. As a result, even when the rotor temperature changes, the motor torque can be matched with the motor torque when the rotor temperature is in the nominal state, so that motor torque fluctuations and voltage fluctuations due to rotor temperature changes can be suppressed.

Moreover, according to the control apparatus for the induction motor in the first embodiment, the magnetic flux current and the torque current, or the magnetic flux voltage and the torque voltage are detected, and the axis deviation index H is calculated based on the detected values. When the δ-axis component φδ _r of the rotor magnetic flux is obtained from an equation and used as an axis deviation index, it is necessary to accurately grasp each parameter (L _r , L _s , M, R _s, etc.) in the equation. However, according to the method of calculating the axis deviation index H based on the detected value of the magnetic flux current or the like, the parameter necessary for obtaining the δ-axis component φδ _r of the rotor magnetic flux is not required. It can be obtained with high accuracy.

<Second Embodiment>
As shown in FIG. 6 and the like, the axis deviation index H is non-linear with respect to the slip angular velocity ω _se , and its characteristic line has a larger slope as the slip angular velocity ω _se becomes smaller, and the slope becomes larger as the slip angular velocity ω _se becomes larger. Is small. In the region where the slope of the characteristic line is small (the region where the slip angular velocity ω _se is large), the amount of change in the slip angular velocity ω _se with respect to the amount of change in the shaft misalignment index H is large, and thus the deviation ΔH between the axis misalignment index H and the axis misalignment index H0. If the slip angular velocity is to be corrected based on this, an error is likely to occur. Further, a small value is axial deviation indicator H0, when the intersection of the axis deviation indicator H characteristic curve and the axis deviation indicator H0 against slip angular velocity omega _se does not exist, it is impossible to correct the slip angular velocity omega _se .

Therefore, in the induction motor control apparatus according to the second embodiment, the axis deviation index H0 obtained in advance and in which the rotor temperature is in the nominal state is offset by a predetermined amount. Specifically, the axis deviation index H0 is offset by a predetermined amount in a direction in which the change in the slip angular velocity ω _se with respect to the change in the axis deviation index H becomes smaller. In the present embodiment, the larger the axis deviation index H, the smaller the change in the slip angular velocity ω _se with respect to the change in the axis deviation index H. Therefore, by adding a predetermined offset value to the axis deviation index H0, the axis deviation index H0. Is offset.

  FIG. 10 is a diagram showing a detailed configuration of the correction value calculator 18A in the induction motor control apparatus according to the second embodiment. The correction value calculator 18A according to the second embodiment further includes an adder 185 with respect to the correction value calculator 18 according to the first embodiment.

  The adder 185 adds a predetermined offset value to the axis deviation index H0 stored in the H0 storage unit 182.

The PI controller 183 is based on the deviation ΔH between the axis deviation index H calculated by the axis deviation index calculator 181 and the value obtained by adding a predetermined offset value to the axis deviation index H0 by the adder 185. A correction value Δω _se for making the axis deviation index H coincide with the value obtained by adding a predetermined offset value to the index H0 is calculated.

  Instead of the PI controller 183, a PI controller 183A shown in FIG. 8 may be used, or a PI controller 183B shown in FIG. 9 may be used.

FIG. 11 is a diagram showing that the amount of torque fluctuation changes depending on the magnitude of the axis deviation index H0. As shown in FIG. 11, the torque fluctuation is smaller when the offset value is added than before the predetermined offset value is added to the axis deviation index H0. For example, when the offset value is added to the axis deviation index H0, the predetermined offset value always has a value obtained by adding the offset value to the axis deviation index H0 on the characteristic line of the axis deviation index H with respect to the slip angular velocity ω _se . Such an offset value is obtained and set in advance. As a result, by offsetting the axis deviation index H0, there is an intersection between the characteristic line of the axis deviation index H with respect to the sliding angular velocity ω _se and the axis deviation index H0 after the offset, so that the slip angular velocity ω _se is corrected. Can be prevented from being unable to perform.

As described above, according to the control apparatus for the induction motor in the second embodiment, the axis deviation index H0 is offset by a predetermined offset value in the direction in which the change in the slip angular frequency with respect to the change in the axis deviation index H becomes smaller. The correction accuracy of the angular velocity ω _se can be improved. Further, it is possible to prevent the slip angular velocity ω _{se from} being unable to be corrected to make the shaft misalignment index H coincide with the shaft misalignment index H0 when the rotor temperature is in the nominal state.

<Third Embodiment>
In the induction motor control apparatus according to the first and second embodiments, a fixed value stored in the H0 storage 182 is used as the axis deviation index H0 in which the rotor temperature is in the nominal state. However, the axis deviation index H0 in which the rotor temperature is in the nominal state varies depending on the operating point (operating condition) of the induction motor 1. Therefore, in the induction motor control apparatus according to the third embodiment, the axis deviation index H0 in which the rotor temperature is in the nominal state is obtained and used according to the operating point of the induction motor 1.

  FIG. 12 is a diagram illustrating a detailed configuration of the correction value calculator 18B in the induction motor control apparatus according to the third embodiment. The correction value calculator 18B includes a H0 calculator 186 instead of the H0 storage 182 with respect to the correction value calculator 18 in the first embodiment.

The H0 computing unit 186 stores a map that defines an axis deviation index H0 corresponding to the operating point of the induction motor 1, and the rotor temperature is in a nominal state by referring to the map according to the operating point of the induction motor 1. A shaft misalignment index H0 is obtained. Here, the rotational speed N of the induction motor 1 and the torque command value T ^* are used as indices for determining the operating point of the induction motor 1. Therefore, the H0 calculator 186 obtains the axis deviation index H0 in which the rotor temperature is in the nominal state by referring to the map based on the rotational speed N of the induction motor 1 and the torque command value T ^* .

  Instead of the PI controller 183, a PI controller 183A shown in FIG. 8 may be used, or a PI controller 183B shown in FIG. 9 may be used.

FIG. 13 is a diagram showing that the axial deviation index H0 in which the rotor temperature is in a nominal state varies depending on the operating point of the induction motor 1, and the upper figure shows the relationship between the slip angular velocity ω _se and the axial deviation index H. The figure below shows the relationship between the slip angular velocity ω _se and the motor torque T. The upper diagram shows three characteristic lines in which the relationship between the slip angular velocity ω _se and the axis deviation index H differs depending on the operating point of the induction motor 1. Since the relationship between the slip angular velocity ω _se and the axis deviation index H differs depending on the operating point of the induction motor 1, the axis deviation index when the rotor temperature is in a nominal state is also different as shown in FIG. It fluctuates like H0a, H0b, H0c.

  Therefore, by obtaining the axis deviation index H0 corresponding to the operating point of the induction motor 1, even if the operating point of the induction motor 1 is changed, the slip angular velocity can be corrected with high accuracy, so that vector control is performed with high accuracy. be able to.

Since the axis deviation index H0 also varies depending on the magnitude of the voltage of the DC power supply 2, the rotor temperature is in a nominal state based on the rotational speed N of the induction motor 1, the torque command value T ^* , and the voltage Vdc of the DC power supply 2. The axis deviation index H0 may be obtained.

FIG. 14 shows a configuration of a correction value calculator 18C having a configuration for obtaining an axis deviation index H0 in which the rotor temperature is in a nominal state based on the rotation speed N of the induction motor 1, the torque command value T ^* , and the voltage Vdc of the DC power supply 2. It is a block diagram which shows an example.

The H0 computing unit 186A displays a map that defines an axis deviation index H0 according to the operating point of the induction motor 1 (the rotational speed N of the induction motor 1 and the torque command value T ^* ) according to the voltage Vdc of different DC power supplies 2. I remember more than one. The H0 computing unit 186A refers to a map corresponding to the voltage Vdc of the DC power supply 2, and obtains an axis deviation index H0 in which the rotor temperature is in the nominal state, based on the rotational speed N of the induction motor 1 and the torque command value T ^*. .

  In the induction motor control apparatus according to the second embodiment, a predetermined offset value is added to the axial deviation index H0 in which the rotor temperature is in the nominal state. As this offset value, a value corresponding to the operating point of the induction motor 1 may be used.

  FIG. 15 is a block diagram showing a configuration example of a correction value calculator 18D having a configuration for obtaining an axis deviation index H0 corresponding to the operating point of the induction motor 1 and obtaining an offset value corresponding to the operating point of the induction motor 1. It is. The correction value calculator 18D further includes an offset value calculator 187 and an adder 188 with respect to the correction value calculator 18B shown in FIG.

The offset value calculator 187 stores a map that defines an offset value corresponding to the operating point of the induction motor 1, and obtains an offset value by referring to the map according to the operating point of the induction motor 1. Here, the rotational speed N of the induction motor 1 and the torque command value T ^* are input as indices for determining the operating point of the induction motor 1. Accordingly, the offset value calculator 187 obtains an offset value based on the rotation speed N of the induction motor 1 and the torque command value T ^* .

  The adder 188 adds the axis deviation index H0 obtained by the H0 computing unit 186 and the offset value obtained by the offset value computing unit 187.

  As described above, according to the control apparatus for an induction motor in the third embodiment, a plurality of axis deviation indices H0 are stored according to the operating point of the induction motor, and a plurality of axis deviations are determined based on the operating point of the induction motor. An axis deviation index corresponding to the operating point is extracted from the index H0. Then, the slip angular velocity is corrected so that the detected axis deviation index coincides with the extracted axis deviation index H0. As a result, even when the operating point of the induction motor fluctuates, the slip angular velocity can be corrected with high accuracy, and the motor torque fluctuation due to the temperature change of the rotor can be suppressed.

According to the method of obtaining the offset value according to the operating point of the induction motor, it is possible to obtain an appropriate offset value according to the operating point of the induction motor and further improve the correction accuracy of the slip angular velocity ω _se .

  The present invention is not limited to the embodiment described above. For example, the configurations in the embodiments can be combined as appropriate.

DESCRIPTION OF SYMBOLS 1 ... Induction motor 4 ... Current sensor (current voltage detection means)
11 ... 3-phase / γ-δ AC coordinate converter (current / voltage detection means)
14 ... Slip angular frequency controller (slip angular frequency correction means)
18 ... Correction value calculator 181 ... Axis deviation index calculator (axis deviation index calculation means)
182 ... H0 memory (memory means)
183, 183A, 183B ... PI controller (slip angular frequency correction means)
185 ... Adder (offset means)
186 ... H0 calculator (reference axis deviation index extraction means)
187 ... Offset value calculator (offset value calculation means)

Claims (5)

The current flowing through the stator of the induction motor is converted into a magnetic flux current and torque current on the γδ axis rotation coordinate system synchronized with the power angular frequency obtained by adding the slip angular frequency to the electrical angular frequency of the induction motor, and the rotor magnetic flux In the control apparatus for an induction motor that performs vector control for independently controlling the magnetic flux current and the torque current so as to match the γ-axis,
An axis deviation index calculating means for calculating an axis deviation index indicating a deviation of the rotor magnetic flux with respect to the γ axis;
Storage means for storing a reference axis deviation index when the temperature of the rotor is in a nominal state;
Slip angular frequency correction means for correcting the slip angular frequency so that the axis deviation index calculated by the axis deviation index calculation means matches the reference axis deviation index stored in the storage means;
An induction motor control device comprising: In the control apparatus of the induction motor according to claim 1,
The magnetic flux current and the torque current, or current voltage detection means for detecting the magnetic flux voltage and the torque voltage is further provided,
The shaft deviation index calculating means calculates the axis deviation index based on a detection value of the current / voltage detection means. In the induction motor control device according to claim 1 or 2,
An offset means for offsetting the reference axis deviation index by a predetermined offset value in a direction in which the change in the slip angular frequency with respect to the change in the axis deviation index is reduced;
An induction motor control apparatus characterized by the above. In the induction motor control device according to any one of claims 1 to 3,
The storage means stores a plurality of reference axis deviation indices according to the operating point of the induction motor,
An operating point detecting means for detecting an operating point of the induction motor;
A reference axis deviation index for extracting a reference axis deviation index corresponding to the operation point from a plurality of reference axis deviation indices stored in the storage unit based on the operation point detected by the operation point detection means. Extraction means;
Further comprising
The slip angular frequency correction means corrects the slip angular frequency so that the axis deviation index calculated by the axis deviation index calculation means matches the reference axis deviation index extracted by the reference axis deviation index extraction means. An induction motor control apparatus characterized by the above. In the control apparatus for an induction motor according to claim 3,
An operating point detecting means for detecting an operating point of the induction motor;
An offset value calculating means for calculating the predetermined offset value based on the operating point detected by the operating point detecting means;
A control device for an induction motor, further comprising: