JP3749426B2 - Induction motor control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device that stably operates an induction motor with an inverter without adding a speed detector.
[0002]
[Prior art]
FIG. 6 is a configuration diagram of a control system for stably operating an induction motor with a conventional inverter. In the figure, 1 is a deviation detection for detecting a deviation ωr err between the speed command ωr * and the speed ωr of the induction motor IM2. 3 is a proportional-integral operation (PI) unit for estimating the slip frequency estimated value ωs 1 of IM2 from the deviation ωr err of the deviation detector 1, and 4 is a slip frequency estimated value ωs 1 of the PI unit 3 and the speed ωr of IM2. adder for calculating the output frequency command omega 0 a, 5 an adder 4 outputs frequency command omega V / F controller for calculating an arbitrary voltage command V * by 0, the output frequency command omega 0 of 6 adders 4 And a phase voltage reference signal generator 7 for calculating the three-phase sine wave voltage reference V U * , V V * , V W * according to the voltage command V * of the V / F controller 5. three-phase sinusoidal voltage reference V U *, V V * V W * by three-phase voltage V U applied to IM2, V V, V W, an inverter unit for outputting, 2 three-phase voltage V U of the inverter unit 7, V V, V W induction motor is operated by ( IM) and 8 are speed detectors for detecting the speed ωr of IM2.
[0003]
Next, the operation will be described. When IM2 operated by the inverter unit 7 becomes unstable in the control system configuration shown in FIG. 6, a slip frequency ωs 1 based on the difference between the speed command ωr * and the speed ωr is generated in IM2. At this time, the deviation detector 1 detects the deviation ωr err between the speed command ωr * and the speed ωr of IM2, and the estimated slip frequency ωs 1 * changes until the deviation ωr err becomes zero in the PI unit 3. The adder 4 calculates the output frequency command ω 0 from the slip frequency ωs 1 * and the speed ωr of IM2. Thus, since the conventional method is constituted by the speed feedback control system so that the speed ωr of IM2 matches the speed command ωr * , the induction motor can be operated stably.
[0004]
[Problems to be solved by the invention]
In order to stably control the conventional induction motor, it is necessary to specially install a speed detector 8 for detecting the speed ωr of IM2 as shown in FIG. When the speed detector 8 fails or malfunctions, the speed ωr input to the deviation detector 1 is different from the actual speed of IM2, and the control configuration of FIG. 6 malfunctions, and the speed ωr of IM2 is the speed command ωr. * There was a problem that good operating characteristics could not be obtained.
[0005]
The present invention has been made to solve the above-described problems, and an object thereof is to obtain a control device that stably operates an induction motor using an inverter without using a speed detector.
[0006]
[Means for Solving the Problems]
An induction motor control device according to the present invention is an induction motor control device that drives and controls an induction motor having no speed detector via an inverter. The current detector detects an input current of the induction motor, and the current detection 3φ / 2φ converter by converting the detected current of the generator to 3φ / 2φ converter that calculates the torque component current of the induction motor The low frequency component is passed from the torque component current calculated by the 3φ / 2φ converter , and high frequency noise is cut A bandpass filter that extracts the vibration component of the torque component current, a frequency correction calculation unit having a gain calculation unit that calculates the frequency correction component from this vibration component, and subtracts the frequency correction component from the frequency command input from the outside. A subtractor that calculates an output frequency command, a V / F controller that outputs a voltage command value corrected by the frequency correction based on the frequency command, and the voltage Comprising a decree value and the output frequency command on the basis of outputs three-phase voltage reference phase voltage reference signal generator for controlling the output of the inverter, and controls to operate stably and suppress vibration.
[0007]
In addition, in an induction motor control device that drives and controls an induction motor that does not have a speed detector via an inverter, a current detector that detects an input current of the induction motor,
The current detected by this current detector is 3φ / 2φ converted to calculate the torque component current of the induction motor. The 3φ / 2φ converter, which passes the low frequency component from the torque component current calculated by the 3φ / 2φ converter, and the high frequency noise A band-pass filter that extracts the vibration component of the torque component current and a frequency correction calculation unit having a gain calculation unit that calculates a frequency correction component from the vibration component, and the frequency correction based on the frequency command input from the outside A V / F controller that outputs a voltage command value corrected in minutes and a phase voltage reference signal generator that outputs a three-phase voltage reference based on the voltage command value and controls the output of the inverter, thereby suppressing vibration. Therefore, it is controlled so as to operate stably.
[0008]
Further, the frequency correction component calculation unit includes a weight function generator that weights the torque component current calculated by the 3φ / 2φ converter in accordance with the frequency command or the output frequency command .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a control device for an induction motor according to a first embodiment. In FIG. 1, 5 is a V / F controller that calculates an arbitrary voltage command value V * according to a frequency command ω * , and 6 is an output frequency command ω 0 of a subtractor 14 and a voltage command value V of a V / F controller 5. The phase voltage reference signal generator for calculating the three-phase sine wave voltage reference V U * , V V * , V W * by * , 7 is the three-phase sine wave voltage reference V U * , V of the phase voltage reference signal generator 6 An inverter unit (that is, an inverter) that outputs three-phase voltages V U , V V , and V W to be applied to the induction motor IM2 by V * and V W * , and 2 is a three-phase voltage V U , V V , V of the inverter unit 7 An induction motor (IM) whose operation is controlled by W.
[0010]
Reference numerals 10a, 10b, and 10c denote current detectors that detect currents I U , I V , and I W flowing from the inverter unit 7 to IM2, respectively, and 11 denotes a trigonometric function signal SINω 0 t, COSω according to the output frequency command ω 0 of the subtractor 14. A trigonometric function signal generator 12 for generating 0 t is used to convert the currents I U , I V , and I W of the current detectors 10 a, 10 b, and 10 c into trigonometric function signals SINω 0 t and COSω 0 t of the trigonometric function signal generator 11. 3φ / 2φ converter for calculating the torque component current Iq of IM2 by performing 3φ / 2φ conversion, and 13 is a high pass for extracting an unstable component of the torque component current, that is, a vibration component from the torque component current Iq of the 3φ / 2φ converter 12 filters and, frequency correction calculation section consisting gain calculator Ka for computing the frequency correction amount omega s from unstable component of the torque current, 14 a frequency correction component Starring Omega s and subtracter for calculating an output frequency command omega 0 from the frequency command omega * parts 13, 20 is a subtractor for subtracting the frequency correction amount omega s from frequency command omega *, the output of the subtracter 20 V / F This is input to the controller 5 and reflected in the voltage command value V *.
[0011]
The operation of FIG. 1 will be described. FIG. 2 is a waveform diagram of values at various parts in FIG. When the speed ωr of IM2 is oscillating as shown in FIG. 2A, a slip frequency as shown in FIG. 2B is generated. At this time, the torque component current Iq also generates the vibration component shown in FIG.
Iq ∝ Slip frequency -------------- (1)
[0012]
Only a vibration component is extracted from the torque component current Iq using a high-pass filter, and a frequency correction component ω s shown in FIG. 2D is calculated using the relationship of the following equation (2).
ω s振動 Vibration component of torque current Iq ------------- (2)
[0013]
The subtractor 14 obtains the output frequency command ω 0 from the frequency correction ω s and the frequency command ω * by the following equation (3), and ω 0 = ω * −ω s -------- ------ (3)
Input to the phase voltage reference signal generator 6. Similarly, ω * −ω s is obtained by the subtracter 20 and input to the V / F controller 5 to output the corrected voltage command value V * .
[0014]
The output frequency command ω 0 and the corrected voltage command value V * are input to the phase voltage reference signal generator 6 and calculated by the phase voltage reference signal generator 6. The slip frequency (∝torque current Iq) of IM2 operated with the phase voltage reference signal calculated and output by the phase voltage reference signal generator 6 has no vibration component and is stable as shown in FIG. The operating characteristics of the induction motor thus obtained can be obtained. The gain Ka and the time constant t of the high-pass filter in the frequency correction calculation unit 13 are configured by a volume in the case of an analog circuit, a memory or a self-erasable nonvolatile memory in the case of a digital circuit, and can be easily set. Needless to say, it can be changed.
In the above description, the filter configuration of the frequency correction component calculation unit 13 is a high-pass filter. However, as shown in FIG. 5, the vibration component of the torque component current is extracted from the torque component current I q of the 3φ / 2φ conversion unit 12 . By adopting a band-pass filter that extracts only a desired frequency component that allows low-frequency components to pass and cuts high-frequency noise, more stable operation characteristics can be obtained without impairing steady-state characteristics.
[0015]
In the above description, the frequency command ω * is corrected by the frequency correction amount ω s and input to the V / F controller 5. However, the frequency command ω * is input as it is and the temporary output of the V / F controller 5 is input. The temporary output may be compensated with the frequency correction ω s to obtain the main output of the V / F controller 5.
[0016]
As in the first embodiment, since both the voltage command value V * and the output frequency command ω 0 are corrected by the frequency correction amount ω s , the magnetic flux of the induction motor IM2 is kept constant, Compensation of torque that suppresses vibration can be achieved effectively.
[0017]
Embodiment 2. FIG.
Further, as shown in FIG. 3, even if the frequency correction amount ω s is reflected only on the voltage command value V * by the V / F controller 5, stable operation characteristics can be obtained. This is because even if the applied voltages V U , V V and V W of IM2 are changed, the current corresponding to the torque changes.
By doing in this way, a part of component can be deleted and the objective can be achieved at low cost.
In FIG. 3, the filter configuration of the frequency correction amount calculation unit 13 is a high-pass filter. However, as shown in FIG. 5, the vibration component of the torque component current is extracted from the torque component current I q of the 3φ / 2φ conversion unit 12. By adopting a band-pass filter that passes only a low frequency component and cuts high frequency noise and extracts only a desired frequency component, a more stable operation characteristic can be obtained without impairing the steady state characteristic.
[0018]
Embodiment 3 FIG.
In the first and second embodiments, as shown in FIG. 4, a weight corresponding to the frequency command ω * or the output frequency command ω 0 is set between the frequency correction calculation unit 13 and the 3φ / 2φ conversion unit 12. By adding the weight function generator 30 to be generated, it is possible to obtain stable operation characteristics in the vicinity of a desired operation frequency .
[0019]
【The invention's effect】
As described above, according to the induction motor control apparatus of the present invention, in the induction motor control apparatus that drives and controls an induction motor that does not have a speed detector via an inverter, the input current of the induction motor is detected. Current detector, 3φ / 2φ converter converts current detected by this current detector to calculate torque component current of induction motor 3φ / 2φ converter 3φ / 2φ converter passes low frequency component from torque component current calculated by 3φ / 2φ converter A band-pass filter that cuts out high-frequency noise and extracts the vibration component of the torque component current, a frequency correction calculation unit having a gain calculation unit that calculates a frequency correction component from the vibration component, and a frequency command input from the outside A subtractor that subtracts the frequency correction value to calculate an output frequency command, and outputs a voltage command value corrected by the frequency correction value based on the frequency command. A controller and a phase voltage reference signal generator for controlling the output of the inverter by outputting a three-phase voltage reference based on the voltage command value and the output frequency command, and controlling so as to suppress vibration and operate stably. As a result, stable operating characteristics of the induction motor can be obtained without using a speed detector. The system can be configured at low cost, and there is an effect that stable operation characteristics of the induction motor can be obtained. Further, the filter for extracting the vibration component of the torque component current is a bandpass filter that passes the low-frequency component and cuts the high-frequency noise, so that more stable operation characteristics can be obtained without impairing the steady-state characteristics.
[0020]
In addition, in an induction motor control device that controls the drive of an induction motor without a speed detector via an inverter, a current detector that detects the input current of the induction motor, and the detected current of this current detector is converted into 3φ / 2φ Then, the 3φ / 2φ converter that calculates the torque component current of the induction motor passes the low frequency component from the torque component current calculated by the 3φ / 2φ converter , cuts the high frequency noise, and extracts the vibration component of the torque component current. A frequency correction component calculation unit having a band pass filter and a gain calculation unit for calculating a frequency correction component from the vibration component, and outputting a voltage command value corrected by the frequency correction component based on a frequency command input from the outside. / F controller and a phase voltage reference signal generator that outputs a three-phase voltage reference based on the voltage command value and controls the output of the inverter, and suppresses vibration and And controls to operate the, it is possible to obtain a stable operation characteristics of an induction motor without using a speed detector, the system can be further low cost. Further, the filter for extracting the vibration component of the torque component current is a bandpass filter that passes the low-frequency component and cuts the high-frequency noise, so that more stable operation characteristics can be obtained without impairing the steady-state characteristics.
[0022]
In addition, the frequency correction calculation unit has a weight function generator that weights the torque component current calculated by the 3φ / 2φ converter according to the frequency command or output frequency command, so that it is stable near the desired operating frequency. Driving characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an induction motor control apparatus according to Embodiment 1 of the present invention;
FIG. 2 is a waveform diagram of values at various parts in FIG. 1;
FIG. 3 is a block diagram showing a control device for an induction motor according to a second embodiment. It is.
FIG. 4 is a configuration diagram showing a main part of a control device for an induction motor according to a third embodiment.
FIG. 5 is a configuration diagram showing a main part of a control device for an induction motor according to Embodiments 1 and 2 ;
FIG. 6 is a configuration diagram of a control system for stably operating a conventional induction motor.
[Explanation of symbols]
2 Induction motor 5 V / F controller 6 Phase voltage reference signal generator 7 Inverter 11 Trigonometric function signal generator 12 3φ / 2φ conversion unit 13 Frequency correction calculation unit 14 Subtractor 20 Subtractor 30 Weight function generator.

Claims (3)

In an induction motor control device that drives and controls an induction motor that does not have a speed detector via an inverter,
A current detector for detecting the input current of the induction motor,
A 3φ / 2φ converter for calculating a torque component current of the induction motor by converting the detected current of this current detector by 3φ / 2φ,
A bandpass filter that passes the low frequency component from the torque component current calculated by the 3φ / 2φ converter, cuts out the high frequency noise and extracts the vibration component of the torque component current, and gain calculation that calculates the frequency correction component from this vibration component A frequency correction calculation unit having a unit,
A subtractor that calculates the output frequency command by subtracting the frequency correction from the frequency command input from the outside,
A V / F controller that outputs a voltage command value corrected by the frequency correction based on the frequency command;
And a phase voltage reference signal generator for controlling the output of the inverter by outputting a three-phase voltage reference based on the voltage command value and the output frequency command,
A control device for an induction motor that performs control so as to suppress vibration and operate stably. In an induction motor control device that drives and controls an induction motor that does not have a speed detector via an inverter,
A current detector for detecting the input current of the induction motor,
A 3φ / 2φ converter for calculating a torque component current of the induction motor by converting the detected current of this current detector by 3φ / 2φ,
A bandpass filter that passes the low frequency component from the torque component current calculated by the 3φ / 2φ converter, cuts out the high frequency noise and extracts the vibration component of the torque component current, and gain calculation that calculates the frequency correction component from this vibration component A frequency correction calculation unit having a unit,
A V / F controller that outputs a voltage command value corrected by the frequency correction based on a frequency command input from the outside;
And a phase voltage reference signal generator for controlling the output of the inverter by outputting a three-phase voltage reference based on the voltage command value,
A control device for an induction motor that performs control so as to suppress vibration and operate stably.   3. The induction motor according to claim 1, wherein the frequency correction component calculation unit includes a weight function generator that weights the torque component current calculated by the 3φ / 2φ converter in accordance with the frequency command or the output frequency command. Control device.

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