JP2580101B2 - Method of setting control operation constants for induction motor control system - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a control operation constant setting method for an induction motor control system for setting a control operation constant of a control device for driving an induction motor.

[Background of the Invention]

In a known AC motor control device such as a vector control inverter, a control constant is set based on a motor constant such as a leakage impedance, an exciting inductance, a rotor secondary time constant, and the like. Conventionally, the setting is made based on the design value of the motor constant.However, the control constant must be changed for each motor to be used, which is complicated, and the control calculation is performed because of the mismatch between the design value and the actual value. It is a problem that errors occur.

In the related art, a method of measuring the impedance of a DC load such as a DC motor based on an output current and a voltage of a converter that supplies power to the motor is well known. In the case of DC machines, their equivalent circuits are each a single resistor,
The resistance value is represented by an inductance and a back electromotive force, and the resistance value is measured based on a value of a ratio of a motor voltage to a current (a steady value) when a predetermined current is applied to the motor. Further, the inductance can be measured from the rising time constant of the motor current when a predetermined voltage is applied to the motor stepwise. Then, a control constant is set based on the measurement result.

On the other hand, in the case of an induction motor, its equivalent circuit is represented by a plurality of resistances, inductances, etc., each of which must be measured separately, and since induction motors generally have multiphase windings The phase of the current flowing through each winding at the time of measurement (polarity and magnitude of current in the case of direct current) and the phase of each winding voltage induced by the flow of current (polarity and magnitude of voltage in the case of direct current) This must be taken into account and cannot be met by the conventional methods described above.

[Object of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problem. In a converter for vector control or the like, attention is paid to the fact that the magnitude, frequency and phase of the output current can be controlled with high accuracy. To supply a predetermined current to the motor, measure the electric constant of the induction motor with high accuracy based on the motor voltage induced at that time, and set a control operation constant of the induction motor control system based on the measurement result. .

[Summary of the Invention]

A feature of the present invention resides in an induction motor control system including a converter that outputs an AC having a variable voltage and a variable frequency to an induction motor, and a control device that controls an output amount of the converter to drive the motor. The control device includes a motor constant calculation unit for measuring and calculating a motor constant of the motor, and outputs a command signal according to a measurement condition of one constant of the motor from the calculation unit to the control device before actual operation. The control device controls the output amount of the converter according to the command signal, supplies AC or DC to the motor, and inputs the output amount of the converter at that time to the arithmetic means. Measuring and calculating the motor constant of the motor by the calculating means based on the output amount, and setting a control calculation constant of the control device based on the calculated motor constant. That.

(Example of the invention)

FIG. 1 is a circuit diagram of an embodiment in which the motor constant measuring method of the present invention is applied to a PWM inverter control induction motor system. 1 is GTO (Gate Turn-off Thyris)
tor) or a PWM inverter composed of a transistor and a diode, 2 is an induction motor to be measured, 3 is an oscillator for generating a two-phase sine wave signal having a frequency proportional to the frequency command signal ω ₁ ^* , and 4 is a current command. signal of the exciting current component i _d ^* and the torque current component i _q perpendicular thereto
A coordinate converter that outputs a command pattern signal i ₁ ^* of the output current of the inverter based on ^* and the output signal of the oscillator 3;
5 is a current detector for detecting an instantaneous value i ₁ of the inverter output current, 6 a GTO on and off controlled in accordance with a deviation of i ₁ ^* and i _1, the control to be proportional to i ₁ to i ₁ ^* The current controller 7 is a gate circuit for supplying a gate signal to the GTO. Note that 5 to 7 have three phases in total, but the other 2
The phase components are not shown. 8 is a voltage component detector for detecting a respective axial components v ₁ ^d and v ₁ ^q of the orthogonal rotation coordinate system of the motor voltage, 9 i _{d ^*,} i _{q ^*,} and outputs the command signals, such as omega ₁ ^*, maintaining the inverter output current to a predetermined value, the motor constant measuring electrical constants of the motor on the basis that when the obtained detection signal V ₁ ^d and v ₁ ^q and the aforementioned i _{d ^*,} the i _q ^* and omega ₁ ^* It is an arithmetic unit. In addition, since components 1 to 7 use the components of the inverter device, what is newly required for implementing the present invention is a voltage component detector 8 and a motor constant calculator 9.

Next, the operation of the above device will be described. Coordinate converter 4 based on the signal of the current command signal i _d ^* and i _q ^* and the oscillator 3 performs the following calculation, the two-phase current command pattern signals i
Output _α ^* and _iβ ^* .

here, Further, according to the following equation, the three-phase current command signal i ₁ ^* (i _U ^* , i
_V ^*, _i ^{W *)} is taken out.

This time _i ^{U *} _~i ^W * is represented by the following formula.

here, These i ₁ ^* and the current detection signal i ₁ are compared in each phase, and the GTO of the inverter is turned on / off according to the deviation. As a result, the inverter output current is controlled so as to be proportional to i ₁ ^* .

On the other hand, the voltage component detector 8 detects orthogonal two-axis components v ₁ ^d and v ₁ ^q of the motor voltage according to the following equation.

Where v ₁ ^α = v _U v _{U to} v _W : motor phase voltages Here, the relationship between the voltages v ₁ ^α , v ₁ ^β , v ₁ , v ₁ ^d and v ₁ ^q and the currents i ₁ ^α , i ₁ ^β , i ₁ , i _The relationship for ₁ ^d and i ₁ ^{q is} shown in the vector diagram of FIG. The α-axis and β-axis orthogonal stator coordinate, d-axis and q-axis are orthogonal rotation coordinate axes rotating at an angular frequency omega _1. Now, the i _d ^* and i _q ^* as described above is set to a predetermined value (3) of the inverter output current i ₁ flows according to the relationship (Fig. 2 shows a case of i _{q *} ^{= 0).} At this time, an induced voltage is generated in the motor.
The voltage vector v ₁ can be considered by being decomposed into a d-axis component v ₁ ^d and a q-axis component v ₁ ^q as shown. Next, the principle of the motor constant measuring method of the present invention will be described. Hereinafter, the primary resistance r ₁ of the induction motor, the secondary resistance r ₂ ′, and the leakage inductance l ₁
The measuring method of + l ₂ ′, the exciting inductance L ₁ and the secondary time constant T ₂ will be described in order.

[Measurement of r ₁ ] The v ₁ ^d and v ₁ ^q in the steady state are given by the following equations.

Where i ₁ ^d , i ₁ ^q : d-axis and q-axis components of primary current i ₂ ^d , i ₂ ^q : d-axis and q-axis components of secondary current where secondary currents i ₂ ^d and i _{2 Since} ^q is an unmeasurable quantity for a cage induction machine, delete them. In a steady state, the following equation holds for the secondary current and the primary current.

Here, ω _s : slip angular frequency If equation (5) is used to eliminate i ₂ ^d and i ₂ ^q in equation (6), v ₁ ^d is represented by the following equation.

Here, i ₁ ^q = 0, ω ₁ = 0 and ω _s = 0 (DC excitation,
If the condition of (rotation stop) is set, v ₁ ^d = r ₁ i ₁ ^d (8) v ₁ ^d can be detected by using the above-described voltage component detector 8, and i ₁ ^d can be detected as described above. It is known because it is controlled in proportion to the current command signal _id ^* . Therefore, r ₁ can be measured based on equation (8).

[Measurement of r ₂ ′] Next, by setting i ₁ ^q = 0, ω ₁ = ω _s, that is, the condition of exciting at a constant frequency when the rotation is stopped, Here, r _{² 2} «ω to the primary angular frequency ω _{1 1 ²} (l ² +
L ₂ ) If we set the condition of ² , Here, since r ₁ is known from the above, the primary conversion value r ₂ ′ of the secondary resistance can be measured.

[Measurement of l ₁ + l ₂ ′] (5) When v ₁ ^q is obtained from equation (6), Here, if i ₁ ^q = 0, ω ₁ = ω _s, that is, if the condition of exciting at a constant frequency when the rotation is stopped is set, Furthermore, under the condition that r ₂ ≪ω ₁ (l ₂ + L ₂ ), Here, v ₁ ^q can be detected using the voltage component detector 8 described above, and i ₁ ^d and ω ₁ are known because they are controlled in proportion to their setting signals _id ^* and ω ₁ ^*. . Therefore, the leakage inductance l ₁ + l ₂ ′ can be measured.

[L measurements _{1] ^{i 1 q =, ω 1 =}} 0, the omega _{s =} 0 and i ₁ ^d to set the conditions for step changes. The inverter output current can be controlled at high speed in accordance with the operation of the current control circuit. Was it by giving i _d ^* in connexion step change, a i ₁ ^d can step to change. Under the above conditions, the following equation is established.

^{_{v 1 d = (r 1 +}} P (l 1 + L 1)) i 1 d 1 + PMi 2 d ...... (14) 0 = PMi 1 d 1+ (r 2 + P (l 2 + L 2)) i 2 d ...... (15 Here, 1 is a step function. Further, using equation (15) to eliminate i ₂ ^d in equation (14) Here, since r ₁ is known from the above, r ₁ i ₁ ^d is eliminated, and both sides of equation (16) are integrated. Here, if the integration of T ₂ = (l ₂ + L ₂ ) / r _{2 is performed} for a period sufficiently longer than T ₂ , ∫v ₁ ^dd t (l ₁ + L ₁ ) i ₁ ^d ... (18) ₁ can be approximated by the following equation, as is well known, based on l ₁ + l ₂ 'obtained by the equation (13).

According to the but connexion (18), v ₁ the integral value of ^d by dividing by i ₁ ^d of the setting signal i _d ^* seek l ₁ + L _1, L ₁ is obtained by subtracting a from l ₁ it .

[Measurement of T ₂ ] In equation (17), since l ₁ ≪L ₁ , the integral value of v ₁ ^d is i ₁ ^d
Constant is nearly first-order lag change in T ₂ time against step changes in. The is a T ₂ to determine it by measuring the time until connexion integrated value reaches 63% with respect to its end value.

The above is the measurement principle. The above-described calculation is performed by a motor constant calculator 9 composed of a microcomputer or the like. The operation processing flowchart is shown in FIGS.

FIG. 3 is a flowchart for measuring r ₁ according to the principle described above. First, the frequency command signal ω ₁ ^* to the oscillator is set to zero (31), and then _id ^* is set to a predetermined value, _iq ^* is set to zero, and i ₁ ^d is supplied to perform DC excitation (32). Then, v ₁ ^d detected by the voltage component detector 8 is passed through a filter, and then AD 1
The digital signal is converted into a digital signal by the converter and taken into the microcomputer (33), and v ₁ ^d is proportional to i ₁ ^d by _id ^*.
To obtain r ₁ (34).

FIG. 4 is a flow chart for measuring r ₁ by another method. When DC excitation is performed as described above, ω ₁ ^* t shown in equation (1) is Set (to Purisetsuto output signal phase of the oscillator 3 of FIG. 1), when the i _d ^* is set to zero i _q ^* to a predetermined value, or the equation (1) i _alpha ^* is zero Further, from equation (2), i _U ^* = 0, Becomes On the other hand, from equation (4), in this case, It was but detected a connexion VW Aisaki voltage v _VW, resistance r ₁ is obtained if divided by i _d ^*. FIG. 4 illustrates the above calculation contents.

In this method, the current always flows through the V-phase and W-phase. Therefore, the voltage detection only needs to detect the voltage between the V-phase and the W-phase (DC of constant polarity), and only one voltage sensor (photocoupler, etc.) is required. The feature is that the area around the sensor is simpler than the above-mentioned method.

FIG. 5 is a flowchart for measuring r ₂ ′ according to the principle described above. First omega ₁ ^* Set the example to 314rad / s (50Hz) (51 ), by alternating current excitation flowing i ₁ ^d and then i _d ^* is set to zero i _q ^* to a predetermined value (52), In this case, i ₁ ^d is set to a small value such that the motor does not rotate, and a condition that ω ₁ = ω _s is set. Captures the same way as described above v ₁ ^d to microcomputer (53), v dividing the ₁ ^d in i _d ^* r ₁ +
Find r ₂ ′ (54), and subtract r _{1 found} earlier,
Compute r ₂ '(55).

FIG. 6 is a flowchart for measuring l ₁ + l ₂ ′ according to the principle described above. First, ω ₁ ^* is set as in FIG. 5 (61), and AC excitation is performed (62). Capture v ₁ ^q (6
3), v by dividing the ₁ ^q in omega ₁ ^* and _i ^{d *} Request l ₁ + l ₂ '.

FIG. 7 is a flowchart for measuring the L ₁ in accordance with the principles described previously. First omega ₁ ^* was set to zero (71), then flow i _d ^* in step changes the given i ₁ ^d to coordinate converter 4 step manner (72). The generated v ₁ ^d is detected and taken into the microcomputer (73). It should be noted that this acquisition is performed every cumulative addition width Δt seconds described later. Next I took in this time
v ₁ ^d is compared with the previously stored v ₁ ′ ^d , and v ₁ ^d is taken every Δt seconds until the ratio becomes equal to or greater than a predetermined value close to 1, and cumulative addition is performed (74 and 75). If the above ratio is complete the cumulative addition is when becomes such greater than a predetermined value, calculates the l ₁ + L ₁ by dividing the addition result by i _d ^* (76). Further, L ₁ is subtracted from l ₁ + L ₁ according to the equation (19) to calculate L ₁ (77).

In addition, as in the case of FIG. If set to, it calculates L ₁ on the basis of the VW phase voltage v _VW. Because In the case of (1), the expression (20) is satisfied. Naturally, in this case, the flow chart is the same as in FIG.

FIG. 8 is a flowchart for measuring T ₂ in accordance with the principles described previously. First, ω ₁ ^* is set to zero (81), and then the same _id ^* as in FIG. 7 is given (82). And v ₁ ^d every Δt seconds
(83), and the cumulative addition vv ₁ ^d Δt of v ₁ ^d is calculated (84). The above-described cumulative addition is continued every Δt seconds until the added value reaches 63% of the end value obtained in FIG.
Five). Complete the addition if reaches 63%, obtaining a T ₂ than the accumulated value ΣΔt of Δt so far (86). T ₂ is Therefore it can also be determined by dividing the L ₁ measured earlier in r ₂ '.

Each motor constant calculated as described above is stored in a storage element and used for setting a control calculation constant of the inverter control device described below.

FIG. 9 is a circuit configuration diagram of an induction machine vector control device, showing an applicable example of the present invention. 1 to 7 are the same as those in FIG. 10 the speed command unit for commanding the rotational speed, 11 speed detector 12 is speed deviation構巾outputting a ^* torque current command i _t, 13 the magnetic flux command for outputting a magnetic flux command phi ^* of the electric motor vessel, 14 excitation current command calculator which outputs an excitation current command i _m ^* based on the magnetic flux command, 15
Slip frequency command calculator for outputting the i _t ^* a i _m ^* divided by to slip angular frequency command ω _s ^*, 16 is omega _s ^* and the added to the rotational speed omega _r inverter frequency command signal omega ₁ ^* It is an adder to output.

Since the principle of the vector control is well known, a detailed description thereof will be omitted.
₁ |, the phase θ and the frequency ω ₁ are controlled to perform high-speed response and high-precision control.

Here, ω ₁ : primary angular frequency ω _r : rotational angular frequency ω _s : slip angular frequency Here, the control satisfying the relationship of the expressions (22) and (23) is performed by the coordinate converter 4 and the current adjustment described above. This is performed in accordance with the operation of the container 6. Further, the control of the relation of the expression (24) is performed in accordance with the operation of the arithmetic unit 15 and the adder 16.

Incidentally, i _m ^* is taken in accordance with the following formula calculator 14.

That L ₁ measured described above this time is used as a processing constant. The aforementioned T ₂ is used when performing a calculation in calculator 15 (24). In the case where the inverter control device is configured by a micro computer, the setting of the operation constants is performed by performing the operation program constant setting based on the motor constants measured and stored as described above, and In the case of being constituted by an analog circuit, it is possible to perform the operations of the equations (24) and (25) using a divider or a multiplier.

FIG. 10 is a circuit configuration diagram of an induction machine vector control device, and shows another applicable example of the present invention. 1-8, 10-12 and
15 is the same as FIG. 1 and FIG. 9, and the description is omitted. 16 subtracts the leakage impedance drop of the motor from the voltage component detection signals v ₁ ^d and v ₁ ^q, and induces electromotive force components ed and
leakage impedance compensator for detecting eq, 17 the commander of the induced electromotive force eq, 18 is an excitation current command i _m induced electromotive force deviation increase width for outputting a ^*, 19 correction signal slip angular frequency based on ed An amplifier that outputs Δω _s ^* , 20 adds the aforementioned ω _s ^* , Δω _s ^*, and ω _r to add a frequency command signal ω ₁
^This is an adder that outputs ^* .

The difference from the device of FIG. 9 is that the secondary time constant T ₂ (secondary resistance
r ₂₎ of the second frequency (slip frequency according to ed to compensate for variations due to winding temperature) it was to correct for, and prevents the influence of the core saturation of the electric motor when performing the flux-weakening control there is to provided a control loop for adjusting the excitation current i _m to match the induced electromotive force eq to command value E ^* for.

The leakage impedance compensator 16 performs the calculation shown in the following equation.
Detect ed and eq.

That is, the motor constants of r ₁ , l ₁ , l ₂ ′ measured earlier are used at this time. As in the case of FIG. 9, each motor constant can be taken into these calculations by setting a constant in a calculation program of a microcomputer or by using a multiplier in an analog circuit.

When setting the control constants of the current control system constituted by the current regulator 6 and the like, the measured l ₁ + l ₂ ′ is used. I do.

〔The invention's effect〕

According to the present invention, a command signal is output from the motor constant calculation means, thereby controlling the output of the converter, and forming a closed loop in which the output amount is fed back to the motor constant calculation means, thereby measuring and calculating the motor constant. Is automatically executed, the labor (manual operation) required for measuring and calculating a plurality of motor constants can be greatly reduced, and highly accurate measurement and calculation can be performed.

In addition, the measurement of the motor constant according to the present invention is performed by using a command signal according to the measurement condition of the motor constant output from the motor constant calculating means before the actual operation of the motor, thereby controlling the control system ( Converter and control device), so that a special measuring device for measuring the motor constant can be dispensed with.

Note that the present invention is not limited to an induction motor,
The same applies to a synchronous motor. The converter is not limited to the PWM inverter as described above, but may be of another type.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a motor constant measuring apparatus showing an embodiment of the present invention, FIG. 2 is a vector diagram for explaining the operation principle of the present invention, and FIGS. FIGS. 9 and 10 are circuit diagrams of an induction machine vector control device showing an applicable example of the present invention. 1 ... Inverter, 2 ... Electric motor, 3 ... Oscillator, 6 ...
... current regulator, 8 ... voltage component detector, 9 ... motor constant calculator.

Continuation of front page (72) Inventor Takayuki Matsui 3-1-1, Yachimachi, Hitachi-shi Hitachi Research Laboratory, Hitachi, Ltd. (56) References JP-A-58-72387 (JP, A) JP-A-57- 79469 (JP, A) JP-A-57-91684 (JP, A) "Installation, testing and maintenance of electrical equipment" by Shigehiko Tsuboshima et al., Published by Denki Shoin Co., Ltd. on November 30, 1972 174-184

Claims (6)

(57) [Claims] 1. An induction motor control system comprising: a converter for outputting an AC having a variable voltage and a variable frequency to an induction motor; and a control device for controlling an output amount of the converter to drive the motor. Includes a motor constant calculating means for measuring and calculating the motor constant of the motor, before the actual operation, output a command signal according to the measurement condition of one constant of the motor from the calculating means to the control device,
Controlling the output amount of the converter by the control device according to the command signal, supplying AC or DC to the motor,
The output amount of the converter at that time is input to the arithmetic means, and the arithmetic means measures and calculates the motor constant of the electric motor based on the input output amount, and the control is performed based on the calculated motor constant. A control calculation constant setting method for an induction motor control system, wherein a control calculation constant of a device is set. 2. The method according to claim 1, wherein the primary resistance of the measurement of the motor constant is measured in accordance with a command signal from the motor constant calculation means by setting the frequency of the output amount of the converter to zero. And controlling the magnitude thereof to a predetermined value to excite the motor by direct current, and measuring and calculating the primary resistance based on the output amount of the converter at this time. Calculation constant setting method. 3. The method according to claim 1, wherein the secondary resistance is measured in the motor constant measurement calculation in accordance with a command signal from the motor constant calculation means and the frequency of the output amount of the converter and its frequency. An induction motor control system characterized in that the magnitude is controlled to a predetermined value to excite the electric motor, and the combined resistance of the primary resistance and the secondary resistance is measured and calculated based on the output amount of the converter at this time. Control operation constant setting method. 4. The method according to claim 1, wherein the measurement of the leakage inductance in the measurement calculation of the motor constant is performed in accordance with a command signal from the motor constant calculation means and the frequency of the output amount of the converter and its magnitude. A method for setting a control calculation constant of an induction motor control system, characterized in that the motor is controlled to a predetermined value to excite the motor, and the leakage inductance is measured and calculated based on the output amount of the converter at this time. 5. The method according to claim 1, wherein in the measurement of the motor constant, the excitation inductance is measured by setting a frequency of an output amount of the converter to zero in accordance with a command signal from the motor constant calculation means. And controlling the induction motor control system by changing the magnitude of the current in a stepwise manner and measuring and calculating the excitation inductance based on the integrated value of the output voltage of the converter and the output current value. Calculation constant setting method. 6. The converter according to claim 1, wherein the frequency of the output of the converter is changed to zero and the magnitude of the current is changed stepwise according to a command signal from the motor constant calculating means. A control operation constant setting method for an induction motor control system, wherein a secondary time constant is obtained by measuring a time required for an integrated value of an output voltage of a converter to reach a predetermined value at this time.