JP3231553B2 - Inverter control device control parameter setting method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an inverter control device.
Regarding the control constant setting method, especially the motor constant of the induction motor
Is calculated, and based on the calculated motor constant,
Control constant setting of inverter control device to set control constant
About the method . 2. Description of the Related Art Generally, in a vector control device, each control constant is set based on a motor constant, for example, an excitation inductance and a secondary time constant. For example, Japanese Patent Application No. 59-173713 and Japanese Patent Application No. 58-173713
In the vector control device shown in JP-A-39434, the control constant for calculating the voltage command signal is one of the motor constants.
Secondary resistance, leakage inductance, primary inductance and
It is necessary to set according to the secondary resistance . [0004] Conventionally, the motor constants are manually set based on the set values of the motor constants. Therefore, it is necessary to change the control constant for each motor to be used, which is complicated, and there is a problem that a control calculation error occurs due to a mismatch between the design value and the actual value of the motor constant, and the torque fluctuates. On the other hand, Japanese Patent Application No. 59-212543 addresses this problem. This uses an inverter device to apply a voltage to the motor from the inverter based on the current command, detect the voltage at that time, and measure the motor constant from the relationship between the detected voltage value and the current command value. The control constant is set based on the result. However, in the example shown in Japanese Patent Application No. 59-212543, it is necessary to provide a voltage detector exclusively for constant measurement, and since the voltage waveform is a distorted waveform, the detection accuracy is low, that is,
There is a problem that constant measurement accuracy is low. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for controlling a control constant of a control device.
It is an object of the present invention to provide a method for setting a control constant of an inverter control device which can improve the degree . [0007] The first object of the present invention to achieve the above object is as follows.
A feature of the invention is a method of setting a control constant of a control device that controls an inverter that supplies power to an induction motor based on a voltage command by a computer that outputs the voltage command of the control device, comprising the following steps: Is to have. (A) setting the voltage command and the frequency command of the induction motor to predetermined values , (b) applying an AC voltage output from the inverter to the induction motor based on the predetermined value ,
Rotating the induction motor; (c) detecting a current flowing through the rotating induction motor; and (d) determining, by the computer, a primary inductance of the induction motor based on the detected current. Setting related control constants of the control device. A feature of a second invention for achieving the above object is that a control constant of a control device for controlling an inverter for supplying electric power to an induction motor based on a voltage command (V _1d *, V _1q *) of an orthogonal vector is set as described above. A method of setting by a computer that outputs the voltage command of the control device includes the following steps. (A) setting the voltage command and the frequency command of the induction motor to predetermined values , (b) applying an AC voltage output from the inverter to the induction motor based on the predetermined value ,
Rotating the induction motor; (c) detecting a vector component corresponding to one vector component of the voltage command of the current flowing through the rotating induction motor; (d) the voltage command and the frequency command, and based on the vector component of said detected current, the step of calculating the primary inductance of the induction motor using the computer, causing the computer on the basis of the primary inductance obtained (e) Calculating a control constant of the control device and setting the control constant. In the first invention, the current used for setting the control constant of the control device is detected while the induction motor is rotating. When the induction motor is rotated, that is, when a frequency command is given, the induced electromotive force generated in the induction motor becomes larger than in the rotation stopped state. Therefore, the error between the voltage command value and the induced electromotive force is reduced, and the influence of the error on the detected current is reduced. Therefore, the accuracy of the control constant related to the primary inductance, which is set based on the detected current, is improved. In the second aspect of the invention, the detected current while rotating the induction motor, for calculating the primary-in <br/> Dakutan scan using a vector component corresponding to one vector component of the voltage command, the primary inductance improved scan accuracy is also improved accuracy of control constant is calculated on the basis of the primary inductance. Further, the detected current while rotating the induction motor, the primary inductance using vector components corresponding to one vector component of the voltage command
For computing, reduces the time required for this operation, the load factor of the computer that controls the inverter is reduced. Preferably, the frequency command and the voltage command are gradually increased to rotate the induction motor. By gradually increasing the frequency command and the voltage command, an inrush current generated at the time of starting can be prevented. An embodiment of the present invention will be described below. FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 2 denotes an inverter for supplying a variable frequency alternating current to the induction motor 1 for controlling a primary voltage by PWM control. The coordinate converter 4 converts the voltage commands v _1d *, v _1q * (rotating magnetic field coordinates) from the voltage command setting device 3 and the voltage phase reference signals sinw ₁ * t, cosw ₁ * t into three-phase voltage command signals v _u *, Calculate v _v *, v _w *. The comparator 6 compares the voltage command signal with the carrier from the triangular wave generator 5 and outputs a PWM signal. As a result, the output voltage of the inverter becomes P
The pulse width modulation is controlled by the WM signal, and the instantaneous value of the fundamental wave is controlled in proportion to the voltage command signal. On the other hand, the three-phase currents i _u , i _v , i _{w of} the motor 1
Is detected by the current detector 7, and 2
Axis component current signals i _1d and i _1q (rotating magnetic field coordinates) are detected. Numeral 9 denotes a constant calculator for detecting detected current signals i _1d , i _1q , voltage command signals v _1d *, v _1q *, frequency command signal w ₁ *, and when a speed detector is attached to the motor. _Takes the speed signal wr therefrom and calculates the motor constant. Here, the voltage command setter 3 and the constant calculator 9
Is performed using a microprocessor and its peripheral LSI, and data input / output is automated. First, the principle of a method for measuring a motor constant using the inverter device will be described. Prior to operation, a predetermined voltage is applied to a motor using an inverter device, and a motor constant is calculated based on the resulting motor current. By the way, the motor voltage is v
Control is performed as described below according to _1d *, v _1q *, and w ₁ *. Based on v _1d *, v _1q * and the voltage phase reference signals cosw ₁ * t and sinw ₁ * t, the coordinate converter 4 calculates a three-phase AC voltage command v ₁ * (v _u *, v _v *, v _w *). ## EQU1 ## [Equation 2] [Equation 3] Then, the output voltage V _{1 of the} inverter is calculated as v ₁ *
Control in proportion to On the other hand, the motor currents i _1d , i _1q (rotating magnetic field coordinates) are detected using the current detector 7 and the coordinate converter 8 shown in FIG. [Equation 4] I _{u to} i _w : motor phase currents In the case of the PWM voltage control method shown in FIG. 1, the distortion of the motor phase current is small and is close to a sine wave. In this method of detecting the current by dividing the current into the d-axis component i _1d and the q-axis component i _1q according to the equation (4), the fundamental component (w ₁ ) can be detected by a DC signal, and the detection accuracy is high. The voltage equation of the induction motor in the steady state is given by the following equation based on the biaxial theory of d and q. [0024] [number 5] _{v 1d = r 1 i i d} -w 1 (l 1 + L 1) i 1q -w 1 Mi 2q ... (5) [0025] [6] v _1q = w ₁ (l ₁ + L ₁ ) i _1d + r ₁ i _iq + w ₁ Mi _2d (6) where i _2d , i _2q : d-axis and q-axis components of the secondary current r ₁ : primary resistance l ₁ : primary leakage inductance L ₁ : Primary effective inductance M: Mutual inductance Here, since the secondary current cannot be measured in the case of a squirrel-cage induction machine, this is eliminated as follows. The relationship between the secondary current and the primary current is expressed by the following equation based on the voltage equation for the rotor secondary circuit. W _s · Mi _1q = r ₂ i ₂ d -w _s (l ₂ + L ₂ ) i _2q (7) -w _s · Mi _1d = w _s ( l ₂ + L ₂ ) i _2d + r ₂ i _2d (8) where, w _s : slip angular frequency r ₂ : secondary resistance l ₂ : secondary leakage inductance L ₂ : secondary effective inductance (7), (8) ), I _2d , i in equations (5) and (6)
Eliminating _2q gives: [Equation 10] ## EQU1 ## Next, based on this relational expression, the principle of measuring the individual motor constants will be described. [Measurement of r ₁ + r ₂ ', l ₁ + l ₂ '] v _1d =
v _1d *, v _1q = v _1q * = 0, w ₁ = w ₁ *, w ₁ = w _s , that is, v _1d * is set to a predetermined value, and the conditions for exciting at a constant frequency when the rotation is substantially stopped are as follows. If set, the equations (9) and (10) are given by the following equations. [Mathematical formula-see original document] [0033] [number 12] _{0 ≒ w 1 (l 1 +} l 2 ') i 1d + (r 1 + r 2') i 1q ... (12) here ^{_{r 2 2 «w 1 2 (l}} 2 + L 2) 2 r ₂ ′: primary conversion secondary resistance l ₂ ′: primary conversion secondary leakage inductance Further, when both equations (11) and (12) are combined, the motor resistance and the leakage inductance can be measured and calculated by the following equations. . [Equation 13] [Equation 14] However, the magnitude of the constant determined by the present measuring method is a combined value of the first and second orders, and a separated value is particularly required for the resistance. Separation is performed as follows. [Measurement method of r ₁ ] v _1d = v _1d *, v _1q = v _1q
* = 0, w ₁ * = 0, that is, if v _1d * is set to a predetermined value and the conditions for applying a DC voltage are set, (1) to
From equation (3), each phase voltage is a voltage proportional to the following equation. V _u * = v _1d *, v _v * = v _w = −v _1d * / 2 (15) As a result, a DC current flows through the motor, and the d and q components of the d and q components are detected at that time. The current is obtained from the equation (4), and the following equation is obtained: i _1d = i _u , i _1q = 0 (16) Therefore, from the voltage command value v _1d * of the d-axis component and the current detection value i _1d , one equivalent primary resistance r ₁ can be measured and calculated by the following equation. [Mathematical formula-see original document] The secondary resistance r ₂ can be calculated by subtracting the calculation result of equation (17) from the calculation result of equation (13) obtained by the previous measurement method. [Measurement method of l ₁ + L ₁ ] v _1d = v _1d = 0, v _1q = v _1q * αw ₁ *, w ₁ = w ₁ *, w _s ≒ 0 In other words, v _1q * under no load condition And w ₁ * are set to predetermined values, so-called V / F constant control operation (magnetic flux constant condition)
I do. Here, since there is no load in the equation (10), i _1q ≒ 0, and therefore (l ₁ + L ₁ ) can be measured and calculated by the following equation. (Equation 18) [Method of measuring T ₂ ] The second-order time constant T ₂ is given by the following equation. (Equation 19) Here, r ₂ ′ is (1) in the above-described measurement operation.
It can be obtained from equations 3) and (17), and the primary conversion value l ₂ ′ + L ₂ ′ can be roughly expressed by the following equation. [Mathematical formula-see original document] [0048] Here, it is assumed that the l ₂ '≒ ₁ 1. Therefore, T ₂ can be obtained by dividing the result (l ₁ + L ₁ ) of equation (18) by r ₂ ′. The above-described calculation of the motor constant is performed in the constant calculator 9, and the control constant of the vector control in the voltage command setting device 3 is set based on the calculation result. Since these calculations and setting processes are automatically performed using a microprocessor, the contents of the program will be described below with reference to the flowcharts of FIGS. When the start switch is turned on, FIG.
Is started, and it is determined in block 21 whether or not the automatic measurement of the motor constant is performed. If the measurement has already been performed and it is not necessary to perform the measurement again, the process jumps to block 24, and the operation required for the vector control using the motor constant written in the storage element, that is, the current command i _1d *, v _1d based on i _1q and frequency command w ₁ *
*, V _1q * are calculated. On the other hand, when performing the measurement, the motor constants are measured and calculated according to the order shown in FIG. 3 in block 22, and the results are stored in the storage element. The control constant of the used vector control is calculated and stored in the storage element. Next, in block 24, the vector control calculation is performed using the above-mentioned control constants to control the speed of the electric motor. [0052] Measurements of the electric motor constant, there are three modes to block 31-33 as shown in FIG. 3, in turn, r ₁
+ R ₂ 'and l ₁ + l ₂ ', r ₁ , l ₁ + L ₁ are measured. Since each measurement has been described above, the procedure of each measurement method will be described below with reference to the flowcharts of FIGS. In FIG. 4, first, at block 41, v _1q * =
0, v _1d *, w ₁ * are set to predetermined values. At this time, v _1d
Is small and the torque is small, so that the motor remains stopped and the above-mentioned condition of w _s = w ₁ is satisfied. Next, in block 42, the signals of i _1d and i _1q are fetched, and block 4
In step 3, r ₁ + r ₂ 'is calculated from equation (13), and in block 44, l ₁ + l ₂ ' is calculated in accordance with equation (14). In FIG. 5, first, at block 51, v _1q * =
0, w ₁ * = 0, v _1d * are set to predetermined values. Next, at block 52, the signal of i _1d is fetched and at block 53 (1
7) Calculate r ₁ from the equation. Further, in block 54, r ₁ is subtracted from r ₁ + r ₂ ′ calculated in block 43 to calculate r ₂ ′. In FIG. 6, first, at block 61, w ₁ *
And v _iq are set to the motor constant value for operation. In order to avoid an inrush current at the time of starting, w ₁ * and v _iq * are set at a constant rate, and after completion of acceleration, signals of i _1d and i _1q are taken in block 62, and signals are obtained in block 63 from equation (18). Calculate l ₁ + L ₁ . Further, based on this result, T ₂ is calculated in block 64 from T ₂ = l ₁ + L ₁ / r ₂ ′. Based on the above measurement results, control constants are set, and thereafter, speed control by vector control is performed. Next, the case where the present invention is applied to a voltage source vector control device (for example, described in Japanese Patent Application Laid-Open No. 58-39434) will be described with reference to FIG. 1 to 10 are the same as those in FIG. This control method is the speed command w _r * and the speed detection signal w _r torque current command corresponding to the deviation of i _1q * and the excitation current command i _1d * and the frequency command w ₁ *
, The voltage commands v _1d *, v _1q * are calculated according to the following equations. V _1d * = r ₁ i _1d * − (l ₁ + l ₂ ′) w ₁ * i _1q * (21) v _1q * = (l ₁ + L ₁₎ ) W ₁ * i _1q * + r ₁ * i _1q * (22) Here, the control constants (r ₁ , l ₁ + l ₂ ′, l ₁ + L ₁ ) are set from the calculation result of the constant calculator 9. The exciting current command i _1q * is supplied to the exciting current command device 32 so that the motor magnetic flux becomes a predetermined value (φ = L ₁ i _1d *).
Is set by On the other hand, i _1q * is the speed command w _r * and the actual speed w _r
Is obtained from the output of the speed controller (ASR) 33 according to the deviation of. The gain of the ASR is the moment of inertia J of the mechanical system.
J can be measured, for example, by the method described in Japanese Patent Application No. 59-212543. Next, w ₁ * is the speed detector 1
Obtained from the signal w _s * sum of the actual speed signal w _r and a slip frequency calculator 34 than 0, the two-phase signal from the oscillator 35 sin w ₁ t
*, Cosw ₁ t * are output. Here, the calculator 34 calculates the slip angular frequency w _s * from i _1d *, i _1q * and T ₂ according to the following equation. [Mathematical formula-see original document] T ₂ here is also automatically set using the measurement result of the constant calculator 9. As described above, with respect to the setting of the control constant related to the motor constant in the vector control device, according to the present invention, before the actual operation, the motor control is performed by the voltage control signal and the current detection signal of the vector control device. Is simply measured, and the control constant is automatically adjusted based on the result. Therefore, the labor for adjustment is greatly reduced, and a vector control device which is easy to handle can be provided. FIG. 8 shows another embodiment to which the present invention is applied, and shows an application example to a vector control device not using a speed sensor. The details of the operation of this apparatus are described in Japanese Patent Application No. 59-173713, and will be briefly described here. In the figure,
2, 4 to 9, 31 to 34 are the same as those in FIG. The difference from FIG. 7 is that vector control is performed without using a speed detector. Inverter output current i
₁ and a voltage phase reference signal sinw ₁ t, cosw ₁ * t, a torque component current i _1q is detected, and a primary frequency w is determined by a frequency controller (AFR) 35 in accordance with a deviation from the command value i _1q *. ₁ * control. Further, in the slip frequency calculator 34, i
Calculates the slip angular frequency w _s * from _1q, to speed control obtains the estimated value w _r of the rotation speed subtracted then w ₁ *. Also in this control device, the motor constant is calculated by the constant calculator 9 from the voltage command signal and the current detection signal, and the control constant of each control unit can be determined based on this. According to the first aspect, the accuracy of the control constant related to the primary inductance, which is set based on the detected current, is improved. According to the second invention, 1 Tsugii <br/> improves Ndakutan scan accuracy is also improved accuracy of control constant is calculated based <br/> the primary inductance. Furthermore, 1
It reduces the time required for the calculation of the next inductance, the load factor of the computer that controls the inverter is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an inverter device showing one embodiment of the present invention. FIG. 2 is a flowchart of a calculation content in the present invention. FIG. 3 is a flowchart of a calculation content according to the present invention. FIG. 4 is a flowchart of a calculation content according to the present invention. FIG. 5 is a flowchart of a calculation content according to the present invention. FIG. 6 is a flowchart of a calculation content according to the present invention. FIG. 7 is a configuration diagram of a control device to which the present invention is applied. FIG. 8 is a configuration diagram of a vector control device showing another embodiment of the present invention. [Description of Signs] 1. Induction motor, 2. Inverter, 3. Command setting device,
4, 8 coordinate converter, 7 current detector, 9 motor constant calculator.

   ────────────────────────────────────────────────── ─── Continuation of front page       (56) References JP-A-60-183953 (JP, A)                 JP-A-61-10983 (JP, A)

Claims (1)

(57) [Claims] A method for setting a control constant of a control device that controls an inverter that supplies power to an induction motor based on a voltage command by a computer that outputs the voltage command of the control device, comprising the following steps: How to set control constants for inverter control device. (A) setting the voltage command and the frequency command of the induction motor to predetermined values, (b) applying an AC voltage output from the inverter to the induction motor based on the predetermined value,
Rotating the induction motor; (c) detecting a current flowing through the rotating induction motor; and (d) determining, by the computer, a primary inductance of the induction motor based on the detected current. Setting related control constants of the control device. (E) The frequency command and the voltage command are gradually increased
Rotating the induction motor. 2. A method of setting a control constant of a control device that controls an inverter that supplies power to an induction motor based on a voltage command (V1d * · V1q *) of an orthogonal vector by a computer that outputs the voltage command of the control device. And a control constant setting method for an inverter control device, the method comprising: (A) setting the voltage command and the frequency command of the induction motor to predetermined values, (b) applying an AC voltage output from the inverter to the induction motor based on the predetermined value,
Rotating the induction motor; (c) detecting a vector component corresponding to one vector component of the voltage command of the current flowing through the rotating induction motor; (d) the voltage command and the frequency Calculating the primary inductance of the induction motor using the computer based on the command and the detected vector component of the current; and (e) calculating the primary inductance of the control device by the computer based on the obtained primary inductance. Calculating a control constant and setting the control constant; (F) The frequency command and the voltage command are gradually increased
Rotating the induction motor.