KR19990069920A - Speed Sensorless Vector Controller Using High Frequency Injection in Induction Motors - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed sensorless vector controller using high frequency injection in an induction motor. In the related art, in the case of the first startup, the response to the load torque is late, so that the startup fails in many cases, and the estimation fails even when the torque of the rated load changes. There was a problem in applying the load. Therefore, the present invention multiplies the high frequency current, the cosine function, and the sine function, respectively, by decomposing the high frequency detection current having positional and velocity observer information into the q-axis and d-axis components in the speed sensorless controller using high frequency injection. A heterodyne processor 22A for outputting an error signal obtained through a new heterodyne process for obtaining a difference between the multiplied values, and a low pass filter for outputting a filtering error signal obtained by performing low pass filtering on the error signal obtained above. (22B), an observer controller (22C) which receives the filtering error signal outputted from the output and calculates a flux speed estimate value through an integrator and gain control, and a value of gain control of slip speed of an induction motor to the flux speed estimate value; A speed compensator 22E for outputting a magnetic flux compensation compensation estimated value to compensate for the speed, and the magnetic flux compensation compensation weight Configured as an integrator (22D) to integrate the value of the magnetic flux to obtain the location estimate, in the sudden change of the load and accurately estimate the speed and position of the magnetic flux, it is a transient state to improve the torque response always enables a successful start-up.

Description

Speed Sensorless Vector Controller Using High Frequency Injection in Induction Motors

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed sensorless vector controller using high frequency injection in an induction motor for greatly improving torque responsiveness to enable fast response of starting or rated load torque. The present invention relates to a speed sensorless vector controller using high frequency injection in an induction motor to enable accurate estimation and to always enable successful startup.

In the case of general-purpose inverters used in the present industry, voltage / frequency control that maintains a constant flux and frequency without a speed sensor is common, and a vector control inverter with a speed sensor is used in a part where speed control or torque control is required.

The attachment of the speed detector requires a separate additional cost, and the attachment of the speed detector is difficult or has a problem due to noise due to a long distance.

In addition, if the motor shaft does not match, another problem occurs.

Therefore, the introduction of a vector inverter capable of speed and tote control without the need for a speed detection device is emerging.

Many methods are currently proposed and applied to industry.

These methods have problems with transient response or having to know the motor constants accurately. The most important thing here is that it is difficult to apply at low speed.

Therefore, by applying a high frequency signal separate from the driving frequency of the fundamental wave to the motor in a way that can be applied at a low speed, the position and velocity information can be found even in the magnetic flux and stop state of the general induction motor by using the polarity and saturation of the magnetic flux. The way is emerging.

However, this method suffers from the initial start-up or rapid change of rated load torque.

The present invention solves this problem and greatly improves the torque responsiveness to enable a quick response of starting or rated load torque.

This invention will be described later.

1 is a circuit configuration diagram of a speed sensorless vector controller using high frequency injection in a conventional induction motor. As shown in FIG. 1, an input stator current command value ( i _qds ^{e *} ) And a voltage command value ( v _qdsl ^{s *} ) Is converted into a current control unit 11 and outputted, and the voltage command value (outputted from the current control unit 11 ( v _qdsl ^{s *} ) And external high frequency applied voltage command value ( v _qdsc ^{s *} ) And the high frequency voltage command value ( v _qds ^{s *} ) And an adder 12 for generating and outputting the high frequency voltage command value (outputted from the adder 12). v _qds ^{s *} ) And coordinate transformation into three phases, and the three-phase command voltage ( v _as , v _bs , v _cs ) Is output to the induction motor 14 to drive the voltage output unit 13 and the three-phase command voltage ( v _as , v _bs , v _cs Three-phase current flowing when the induction motor 14 is driven by i _as , i _bs , i _cs ) And the stator current value obtained by performing stator coordinate transformation on the detected current. i _qds ^s ) And the stator current value output from the current detection and filter circuit 15 i _qds ^s ), And perform synchronous coordinate transformation, and the synchronous current ( i _qds ^e ) And the stator-to-synchronous coordinate converter 16 to provide the current controller 11 to adjust the converted voltage, and the synchronous current output from the stator-to-synchronous coordinate converter 16. i _qds ^e ) To filter high frequency detection current i _qdsc ) And a high frequency detection current detected by the synchronous filter 17 and the synchronous filter 17 for outputting the detected current. i _qdsc ) And a flux velocity estimate (representing the position and velocity estimated therefrom) ) And magnetic flux position estimates ( ), And the estimated magnetic flux position estimates ( ) Is provided to the voltage output unit 13, the stator-to-synchronous coordinate conversion unit 16, and the synchronous filter 17, respectively, to convert the current and voltage to be output into a value according to the magnetic flux position, and It consists of a speed observer 18.

In the above, the position and velocity observer 18, as shown in FIG. i _qdsc ) Is a high frequency current ( i _qsc ) ( i _dsc ) And cosine and sine functions Multiplying each and outputting an error signal [epsilon] obtained through a new heterodyne process for obtaining the difference of the multiplied value, and an error signal [epsilon] obtained from the heterodyne process unit 22A. Filtering error signal obtained by performing low pass filtering on ε _f ) And a low pass filter 22B for outputting the filtering error signal (outputted from the low pass filter 22B). ε _f ) And the flux velocity estimate using the integrator and gain controller And an observer controller 22C for calculating the magnetic flux velocity estimated by the observer controller 22C. ) By integrating the magnetic flux position estimate ( ), And the integrator 22D feeds back the calculated value to the heterodyne processor 22A.

Looking at the prior art configured in this way in detail as follows.

The driving system of the induction motor superimposes a fundamental wave driving frequency component and a signal of a high frequency of a power lower than the driving power to supply power to the stator winding of the induction motor.

At this time, the inherent impedance of the rotor is changed, and a frequency signal composed as a function of the rotational position of the rotor affects the signal of the stator winding part, thereby showing the polarity.

That is, the leakage inductance of the rotor changes as a periodic function of the rotor position by the stator windings.

Information about the rotor position is presented as a function of time and can be used as important information for the driving power of the fundamental frequency to control the speed or torque of the motor.

When the above method is introduced into an induction motor, which is a rotor of a uniform surface without general polarity, the magnetic flux path of the induction motor is saturated and the response of the stator winding to the signal of this part at the signal frequency as a function of the position of the magnetic flux vector. Occurrence of polarity affecting.

The response at the stator windings changes as a periodic function of the flux vector position with stator displacement inductance in the induction motor.

The stator response at the signal frequency is detected and measured to provide a correlation between the signal frequency and the magnitude of the response at the flux vector location.

Information about the position of the magnetic flux vector as a function of time is provided as useful information of the basic frequency driving power of the motor for speed and torque control in motor operation.

Response detection for high frequency signals in the stator windings is detected using heterodyne detection by filtering the mixed signal to separate the modulation of the response to the signal frequency correlated with the angular position of the rotor or the flux vector.

For the same reason as described above, it operates by using a general induction motor luru frequency injection, which will be described based on FIG. 1 and FIG. 2.

The current controller 11 has a stator current value for the q-axis and d-axis currents ( i _qds ^{e *} ) Is input, the stator voltage command value proportional to the stator current value ( v _qdsl ^{s *} ) And output to the adder 12.

Then, the adder 12 receives a high frequency applied voltage command value input from the outside to obtain the polarity information which is important information for controlling the speed or torque of the induction motor. v _qdsc ^{s *} ) Is a voltage command value () provided from the current controller 11. v _qdsl ^{s *} ) And the stator voltage command value ( v _qds ^{s *} ) Is output to the voltage output unit 13.

That is, a signal obtained by overlapping a command value corresponding to a fundamental wave driving frequency component output from the current controller 11 and a command value corresponding to a high frequency from the outside is output to the voltage output unit 13.

The voltage output unit 13 is a pulse width modulation (PWM) voltage type inverter as an inverter system.

Therefore, the voltage output section 13 has a stator voltage command value provided from the adder 12 ( v _qds ^{s *} 3-phase coordinate transformation with respect to v _as , v _bs , v _cs ) Is supplied to the induction motor 14.

Therefore, the induction motor 14 has a three-phase command voltage ( v _as , v _bs , v _cs Start by).

When the induction motor 14 is driven, the induction motor 14 has a three-phase command voltage ( v _as , v _bs , v _cs 3-phase current proportional to i _as , i _bs , i _cs ) Flows.

Then, the current detection and filter circuit 15 is a three-phase current flowing to the induction motor 14 ( i _as , i _bs , i _cs ) And the detected three-phase current ( i _as , i _bs , i _cs ) By stator coordinate transformation i _qds ^s Get)

The stator current thus obtained ( i _qds ^s ) Is provided to the stator-to-synchronous coordinate conversion unit 16.

Then, the stator-to-synchronous coordinate converter 16 converts the current converted into the stator coordinate system back to the synchronous coordinate system, and the fixed current ( i _qds ^e ) Are output to the current control unit 11 and the synchronization filter 17, respectively.

At this time, the current control unit 11 is a fixed current provided from the stator-to-synchronous coordinate conversion unit 16 ( i _qds ^s Stator current value input according to i _qds ^{e *} ), The stator current value ( i _qds ^{e *} ) Is converted into a stator voltage value and output.

In addition, the synchronous filter 17 performs low pass filtering to remove the fundamental frequency in order to obtain information of the high frequency signal. i _qdsc ) And the high frequency detection current ( i _qdsc ) Is output to the position and velocity observer 18.

Accordingly, the position and velocity observer 18 has a high frequency detection current having protrusion polarity information provided from the synchronous filter 17. i _qdsc Through heterodyne process using) and through the derivative and integration ) And magnetic flux position estimates ( Estimate).

The magnetic flux position estimate obtained through this process ( ) Is transmitted to the voltage output unit 13, stator to synchronous coordinate converter 16 and the synchronous filter 17 to adjust the voltage, current value according to the position of the magnetic flux.

As described above, the induction motor 15 is controlled according to the speed and position of the magnetic flux estimated through each unit.

Herein, the operation of the position and velocity observer 18 will be described with reference to FIG. 2.

First, in the synchronous filter 17, a high frequency detection current having protrusion polarity information ( i _qdsc ) Is the high frequency detection current ( i _qsc ) And high-frequency detection current of q-axis component i _dsc Are each broken down into a heterodyne process unit 22A.

Then, in the first multiplier 221 of the heterodyne processor 22A, the high frequency detection current of the q-axis component ( i _qsc ) And the cosine function 223 of the high frequency component Multiply by and output to the non-inverting terminal (+) of the adder 43.

At this time, the second multiplier 222 is a high frequency detection current of the d-axis component ( i _dsc ) And the high frequency sine function (224) Multiply by and output the inverting terminal (-) of the adder 225.

Then, the adder 225 receives the values of the first and second multipliers 221 and 222 respectively input to the non-inverting terminal (+) and the inverting terminal (-) to obtain an error signal ε.

That is, the heterodyne processor 22A obtains an error signal ε to be corrected by the observer controller 22C through the new heterodyne process, and outputs it to the low pass filter 22B.

Then, the low pass filter 22B performs filtering to remove unnecessary components obtained through the heterodyne process, and the filtered error signal ( ε _f ) Is output to the observer controller 22C.

Accordingly, the integrator 226 of the observer controller 22C receives the error signal ( ε _f ), The integrated value is gain-controlled by an arbitrarily set K2 gain control value and output to the non-inverting terminal (+) of the adder 227.

At this time, the observer controller 22C transmits the error signal ( ε _f ) Is gain-controlled by the K1 gain control value and output to the other non-inverting terminal (+) of the adder 227.

The adder 227 then receives an error signal ( ε _f Flux velocity estimate through the integral and gain control ), This magnetic flux velocity estimate ( ) And the magnetic flux position estimate ( ).

However, in the prior art as described above, the observer controller for obtaining the speed and position of the magnetic flux often fails to start due to a slow response to the load torque at the first startup, and fails to estimate even when the torque of the rated load changes. There is a problem in the application of the load occurs.

Accordingly, it is an object of the present invention to solve the conventional problems as described above to provide a speed sensorless vector controller using high frequency injection in an induction motor that can accurately estimate the speed and position of magnetic flux even under a sudden change in load. .

It is another object of the present invention to provide a speed sensorless vector controller using high frequency injection in an induction motor which always enables successful starting to improve the performance of the load response.

1 is a circuit diagram illustrating a sensorless vector controller using a conventional high frequency injection.

FIG. 2 is a detailed circuit diagram of the position and velocity observer in FIG.

3 is a circuit diagram illustrating a position and velocity observer in the present invention.

4 and 5 are experimental waveform diagrams of the motor load torque response comparing the present invention and the conventional method.

*** Explanation of symbols for main parts of drawing ***

11: current control unit 12: adder

13 voltage output unit 14 induction motor

15 current detection and filter circuit 16 stator to synchronous coordinate conversion unit

17: Sync filter 18: Position and velocity observer

22A: heterodyne process section 22B: low pass filter

22C: Observer Controller 22D: Integrator

22E: Speed Compensator

The present invention for achieving the above object is a voltage output for driving an induction motor by a three-phase command voltage generated by the coordinate transformation according to the voltage value corresponding to the input stator current value and the high frequency applied voltage command value from the outside And a high-frequency detection current having the polarity information is obtained through the synchronous filter by detecting the load current flowing through the induction motor through the current detection and filter circuits and the stator-to-synchronous coordinate conversion unit. A speed sensorless vector controller comprising a position and velocity observer for extracting a position estimate and a velocity estimate of a magnetic flux from a high frequency detection current, wherein the position and velocity observer comprises a q-axis and a d-axis component for a high-frequency detection current having bulge polarity information. Multiply each of the decomposed high frequency currents by the cosine and sine functions, and A heterodyne process unit for outputting an error signal obtained through a new heterodyne process for obtaining a difference between the low pass filters, a low pass filter for outputting a filtering error signal obtained by performing low pass filtering on the error signal obtained in the heterodyne process unit, An observer controller that receives the filtering error signal output from the low pass filter and calculates a flux speed estimate through integrator and gain control, and a speed obtained by adding a gain control value to a slip speed of the motor to a flux speed estimate of the observer controller. Comprising a speed compensator for outputting a magnetic flux compensation compensation value compensated for; and integrating the magnetic flux compensation compensation value output from the speed compensator to obtain a magnetic flux position estimate value and outputs the feedback to the heterodyne processor; It features.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a circuit configuration diagram of a speed sensorless vector controller using high frequency injection in the induction motor of the present invention. As shown in FIG. 3, a voltage value corresponding to an input stator current value and a high frequency applied voltage command value from the outside are shown. A synchronous coordinate conversion by detecting a load current flowing to the induction motor through the voltage output unit for driving the induction motor by the three-phase command voltage generated by performing the coordinate conversion according to And a position and velocity observer for filtering and obtaining a high frequency detection current having stimulus information through a synchronous filter, and extracting a position estimate and a velocity estimate of the magnetic flux from the high frequency detection current of the filter. The position and velocity observer uses the q-axis and d A heterodyne process unit 22A for multiplying the decomposed high frequency current by a component, a cosine function, and a sine function, respectively, and outputting an error signal obtained through a new heterodyne process for obtaining a difference between the multiplied values, and the heterodyne process Integrator and gain control by receiving a low pass filter 22B for outputting a filtering error signal obtained by performing low pass filtering on the error signal obtained by the section 22A, and a filtering error signal output from the low pass filter 22B. The observer controller 22C, which calculates the flux speed estimate through the controller, and the slip speed of the motor in accordance with the flux speed estimate of the observer controller 22C. ω _sl ) Is obtained by integrating the speed compensator 22E for outputting the magnetic flux compensation compensation value to compensate for the speed by adding the gain control value, and the flux compensation estimation value output from the speed compensator 22E, and calculating and outputting the magnetic flux position estimate. And an integrator 22D that feeds back to the heterodyne process unit.

Referring to the operation and effect of the present invention configured as described in detail as follows.

A current detection and filter circuit for driving the induction motor 14 through the current control unit 11 and the voltage output unit 12 and detecting current from the driven induction motor 14 to estimate the position and speed of the magnetic flux. (15), the operations of the stator-to-synchronous coordinate converter 16, the synchronous filter 17, and the position and velocity observer 18 are the same as those described with reference to FIG. 1, and the operation of the position and velocity observer 18 Another case is described based on FIG. 3.

When constructing the observer controller 22C for estimating the position and velocity of the magnetic flux in the method of injecting a high frequency signal, it is common to reduce the output frequency band to prevent noise or the like from being output to the output signal of the observer controller 22C. .

As a result, the observer controller 22C responds slowly to the sudden change in the load torque, so that a response delay occurs, so that the magnetic flux cannot correctly estimate the position.

That is, as shown in the relationship between the output torque and the load torque, as shown in the following general equation (1), the output torque does not show a quick response to the load torque.

...............(One)

T _e : Induction motor output torque, T _L : Load torque, P : Number of poles of induction motor

J : Coefficient of inertia, : Motor speed change

The sudden change in the load torque affects the induction motor speed so that the speed change occurs as in Equation (1), and the change in the induction motor speed as in Equation (2) below changes the slip speed of the induction motor. Occurs.

ω _e = ω _r + ω _sl .....................(2)

ω _e : Speed of magnetic flux, ω _r : Induction motor speed, ω _sl : Slip speed of induction motor

In addition, the slip speed of the induction motor has a correlation with the output torque as shown in the following equation (3).

........... (3)

R _r : Motor rotor resistance, R _s : Motor stator resistance, V _s : Motor voltage

L _ls : Motor stator leakage inductance, L _lr : Motor Rotor Leakage Inductance

As can be seen from the relations of equations (1), (2) and (3) above, the occurrence of load torque is represented by the slip speed of the motor and the calculation of slip speed is very fast. And a response delay caused by a low band of the speed estimation observer.

Therefore, when the slip speed of the electric motor is forward-compensated, it is not affected by the delay of the observer controller 22C and compensates for the estimated error due to the sudden change in the load torque.

By configuring the speed compensator together with the gain K3, it is possible not only to adjust the desired responsiveness in the configuration of the speed sensorless vector controller, but also to improve the response to startup problems and load torque.

That is, in the synchronous filter 17, the high frequency detection current having the polarity information ( i _qdsc ) Is the high frequency detection current ( i _qsc ) And high-frequency detection current of q-axis component i _dsc Are each broken down into a heterodyne process unit 22A.

Then, in the first multiplier 221 of the heterodyne processor 22A, the high frequency detection current of the q-axis component ( i _qsc ) And the cosine function 223 of the high frequency component Multiply by and output to the non-inverting terminal (+) of the adder 43.

At this time, the second multiplier 222 is a high frequency detection current of the d-axis component ( i _dsc ) And the high frequency sine function (224) Multiply by and output the inverting terminal (-) of the adder 225.

Then, the adder 225 receives the values of the first and second multipliers 221 and 222 respectively input to the non-inverting terminal (+) and the inverting terminal (-) to obtain an error signal ε.

That is, the heterodyne processor 22A obtains an error signal ε to be corrected by the observer controller 22C through the new heterodyne process, and outputs it to the low pass filter 22B.

Then, the low pass filter 22B performs filtering to remove unnecessary components obtained through the heterodyne process, and the filtered error signal ( ε _f ) Is output to the observer controller 22C.

Accordingly, the integrator 226 of the observer controller 22C receives the error signal ( ε _f ), The integrated value is gain-controlled by an arbitrarily set K2 gain control value and output to the non-inverting terminal (+) of the adder 227.

At this time, the observer controller 22C transmits the error signal ( ε _f ) Is gain-controlled by the K1 gain control value and output to the other non-inverting terminal (+) of the adder 227.

The adder 227 then receives an error signal ( ε _f Flux velocity estimate through the integral and gain control ) Is outputted to the speed compensator 22E.

Then, the slip speed of the motor in the gain controller of the speed compensator 22E ω _sl ) Is multiplied by a gain (K3) proportional to the slip speed and delivered to the non-inverting terminal (+) of the adder (228).

Accordingly, the adder 228 is a slip speed of the gain-controlled motor ( ω _sl ) And the estimated flux rate of the observer controller 22C ( ) And output to the integrator 22D.

In the above, the use of the gain K3 is used as a parameter of the speed compensator 22E to obtain a desired response by fine-tuning the slip speed of the motor sensitive to the parameter of the motor.

As above, the velocity-compensated flux velocity estimate ( ) Is output from the speed compensator 22E to the integrator 22D, the integrator 22D is a speed compensated magnetic flux velocity estimate ( ) By integrating the magnetic flux position estimate ( ).

As described above, since the speed compensator 22E follows the speed and position of the magnetic flux even when the motor is first started or the load torque is applied, the response is reflected in the driving frequency of the stator winding and is difficult to operate. It can be greatly improved.

Looking at the method proposed by the present invention and the conventional method with the comparative experimental waveform shown in FIG. 4, the present invention accurately estimates when the estimated position of the magnetic flux and the magnetic flux coincides with the vertical dotted line as in (b). Shows not only the misalignment estimation as in (a) but also the estimation in the reverse direction of rotation.

Figure 5 compares the estimated position of the actual magnetic flux and the magnetic flux when applying and removing the load torque, the present invention is the exact position of the magnetic flux when matched with the vertical dotted line as shown in (b) (d) of FIG. However, when compared with the present invention, the estimation error appears as shown in (a) of FIG. 4 at a small load torque, and in the conventional case, it is in the same state as in FIG. Shows.

As described above, the present invention is to accurately estimate the speed and position of the magnetic flux even under rapid fluctuations of the load, and to enable a successful start at all times to improve the transient torque response.

Claims (2)

In the velocity sensorless controller using high frequency injection, which consists of a flow motor, current detection and filter circuit, stator-to-synchronous coordinate conversion unit, synchronous filter, heterodyne process, and position and velocity observer to estimate the position and velocity of magnetic flux. The position and velocity observer is a new heterodyne that multiplies the high frequency current, the cosine function, and the sine function, respectively, by decomposing the high frequency detection current having the polarity information into the q-axis and d-axis components, respectively, and obtains the difference between the multiplied values. A heterodyne process unit for outputting an error signal obtained through the process, a low pass filter for outputting a filtering error signal obtained by performing low pass filtering on the error signal obtained above, and an integrator receiving the filtering error signal outputted above And an observer controller for calculating an estimated flux rate through gain control. A speed compensator for outputting a flux compensation compensation estimated value by adding a value obtained by performing gain control to a slip speed of an induction motor, and integrating the flux compensation compensation estimated value to obtain and output a magnetic flux position estimate. A speed sensorless vector controller using high frequency injection in an induction motor, characterized in that it is composed of an integrator that feeds back to the dyne processor. The speed compensator of claim 1, wherein the speed compensator includes a gain controller for compensating a gain with respect to a slip speed of the motor, and an adder for outputting a speed compensated flux position compensation estimate by adding the gain controlled slip speed and the flux position estimate of the observer controller. Speed sensorless vector controller using high frequency injection in the induction motor, characterized in that consisting of.