JPS6242074A - Measuring method for parameter of induction motor - Google Patents

Abstract

PURPOSE:To easily and surely perform an automatic measurement by applying a DC voltage to the primary input of an induction motor from a power inverter, measuring the primary input current and voltage of the motor, finding the primary parameters and calculating the secondary parameters based on prescribed equations. CONSTITUTION:With transistors Tr1, Tr6, etc. in an inverter 21 of the driving power source switched on and off, while a PWM waveform generating circuit 22 set with a definite voltage by a control circuit 11, DC voltage pulses are impressed on the windings U, W, etc. of an induction motor 1. Thus, the voltage and current are measured through a voltage and current detectors 12, 13, and from their ratio, the resistance r1 as a primary parameter is determined by the circuit 11. On the other hand, from the rising transient currents i1(t), i2(t) and the end current Ie of the DC current I, rising time constant T of the current I is determined, and the secondary resistance r2, secondary inductance L2 as the secondary parameters are determined based on the equation 1. In this manner, an automatic measurement of the parameters can be made easily and surely in a standstill state of the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for measuring the constants of an induction motor, and more particularly to a method for automatically measuring the constants of an induction motor connected to an inverter.

B0 Summary of the Invention The present invention is an induction motor connected to an inverter as a drive power source, generates a DC voltage at the output of the inverter, and calculates the induction motor from the primary input current of the rust conductive machine and the snow pressure measurement value at this time. By determining the constants, it is possible to automatically measure the constants of induction motors reliably and easily.

C0 Conventional Technology For variable speed control of induction motors, a slip frequency control method with good responsiveness and precision is known, and recently #-i1! Primary current of motive? Separately control the excitation W current and secondary current,
Is it possible to achieve the same responsiveness as a DC machine by always orthogonalizing the secondary magnetic flux and secondary current vector? A vector control method (for example, Japanese Unexamined Patent Publication No. 165982/1982) has been implemented.

In such slip frequency control and vector control, the constants of the induction motor as the controlled object (FULL) are primary resistance, secondary resistance, -order inductance, secondary inductance 1.
This requires means for determining the slip frequency, -order wR, etc. from the excitation inductance) using arithmetic operations or a function generator.

For this reason, in the past, the necessary constants were determined from the design values or measured values of the motor, and these constants were used to design the control device.
is being built.

D0 Problems that the invention aims to solve In conventional slip frequency control and vector control, the problem with the control device is that it takes time and effort to calculate and measure from design values in order to obtain constant data of the motor, which increases the number of development steps. there were. In particular, in a general-purpose town gearbox, the controlled object IFIIl'
The constant of one machine is unknown, and the number of feet data is required each time depending on the model of the electric motor? Increased effort and testing man-hours? There was a problem. In addition, constant data obtained from design values may have a large error between the design values and the constants of the actual machine, which may require readjustment of the control device or design changes - Solving problem E9 The present invention has been made in view of the above-mentioned problems.In an induction motor connected to an inverter as a drive power source,
A direct vft, 'Ir pressure E is generated at the output of the inverter, and the primary resistance r+ of the induction motor is determined from the ratio E/I of the output current of the inverter and the DC voltage E. and calculate the above by the DC voltage E as the rise transient N of the current flow, Ril
(t+), the respective ratios of il (t2) and the final voltage 'RIe L(t+)/Ie, t+(L2)/Ie
Or guided wI? Secondary resistance r2 and secondary inductance L2 of 1m? It provides the desired measurement method.

28 action By applying a DC voltage from the inverter to the primary input of the induction motor, a current force due to only the primary resistance r1 is equimetrically obtained, and the -order resistance r+? The secondary resistance r2 and the secondary inductance L2 are measured at various intervals starting from the current rise transient phenomenon due to the application of DC voltage.

G. Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a circuit diagram when the present invention is applied to a voltage type vector control device using a PWM type inverter. A primary voltage is supplied to the induction motor 1 from a transistor type inverter main circuit 21. Inverter main circuit 2. Each of the transistors Tr1 to T'ra is controlled by a PWM waveform generating circuit 22 and a gate circuit 25 in terms of switching control, ζn, output voltage, and frequency based on the PWM waveform. Inverter main circuit 2. The primary Ichida supplying mW+machine 1 from
The city! The alI machine 1 is controlled so that the magnetic flux and the secondary current are orthogonal to each other. For this control, the direction of the magnetic flux is set as the α axis, the direction of the secondary current is set as the β axis perpendicular to the α axis, and the command values are α phase-order current 11r and β-phase order current 1.
1r'' is the α-phase-order voltage e1 by multiplying the primary resistance r1 of the motor 1 by the coefficient multipliers 31 and 32, respectively.
It is converted into a two-phase voltage signal of α, β phase-order voltage e1β.

β phase-′eK, 1! The flow command 11β is the speed setting value vs.
and the detected value ωr of the speed detector 4 of the motor, and output as the output of the speed regulator 5.The power supply angular frequency ω0 is determined by the angular frequency calculation circuit 6 as the calculated value of the slip angular frequency ωS and the detected speed value ωr. Obtained from. The angular frequency calculation circuit 6 includes a divider 61 that divides a set value 11- and 11p 'l', and a division result 11β/i 1α of this divider 61.
The coefficient 1/τ2? The coefficient unit 62 for multiplication? What is the angular frequency ωS? calculate. Here, τ2 is the secondary time constant of the motor 1, and the secondary resistance r2 and secondary inductance L
It is a ratio of 2.

τ2 = r, - Phase 1 calculation circuit 7 generates the inverter's three-phase voltage command signal e A 1 e l) from the three-phase voltage signals e1α and 61β.
*9 To obtain e, the sine wave signal sin o+ot and cosine wave signal cos go required for this conversion.
t is obtained from the trigonometric function generating circuit 8 using the power supply angular frequency a1g. Further, the P■ waveform generation circuit 22 is configured to obtain a pulse width modulation waveform by comparing the levels of the three-phase voltage command signal e@*eb*e- and a triangular wave signal (carrier wave), and a triangular wave signal tri-wave circuit for this purpose. w critical angular frequency ωO from 6? The signal is obtained from the triangular wave generating circuit 9 which uses the signal to synchronize with the frequency. This is a rectifier that supplies all of the sarcophagus power to the 10-digit inverter main circuit 21.

In this way, when controlling the primary motor of the motor using a PWM inverter, the coefficient multiplier 3 +
, 3z, the coefficient data corresponding to the primary resistance r of the motor 1 is required, and the coefficient unit 62 requires the secondary resistance r2 of the motor 1 to set the secondary time constant τ2 (= L2/r2). and constant data corresponding to the secondary inductance L2.

As self-tuning means for automatically measuring and setting these constant data, a voltage detector 12 and a current detector 13'f for detecting the output voltage and current of the tuning control circuit 11 and the inverter main circuit 21, respectively, are provided. The tuning control circuit 11 has a control function to adjust the pI of the output waveform of the PWM waveform generation circuit 22, and performs constant data measurement and
When a setting command is given, a DC voltage is generated using the three phases of the inverter main circuit 21, and the primary resistance r is calculated using the detected values from the voltage detector 12 and the current detector 13. ! .

Secondary resistance r2 + secondary inductance L2 and secondary time constant τ2 are determined, and each coefficient of coefficient units 31, 3□, and 62 is automatically set. Below, how to automatically measure constant data using the tuning control circuit 11? Explain in detail.

(1) Measurement of -order resistance r, inverter main circuit 2. For example, transistor T
'rt, Trfl f on/off control, tIITI
Apply DC voltage between windings U and W of rh machine 10. At this time, the control circuit 11 sends the PWM waveform generation circuit 22 a constant voltage V?instead of the voltage command e-1eb*+6°. Set, P
Is the WM waveform output controlled to only allow the output of transistors Tri and Tr6? Furthermore, the output frequency of the triangular wave generating circuit 9 is made constant.

Through such control, a pulse voltage with an on/off ratio determined by the voltage V is applied to the windings U and W, and the detected value of this voltage and W flow is sent from the detectors 12 and 13 to the control circuit 11 as an average voltage, 1 [Representation 3I of the resistance r by the control circuit 11 taken as a current? conduct.

The equivalent circuit of the induction N sand machine lOT type is as shown in Fig. 2, and when the direct R voltage E is applied to n, the steady IIf flow I = -. Here, the voltage applied to the inverter main circuit 21 is the pulse voltage [C;
) Voltage decrease due to switching dead time ED
Including B, -E-EDB ■ =□ ...-(1). Here, in order to eliminate the influence of dead time and improve measurement accuracy, the control circuit 11 changes the control rate and measures the average direct current 100 and the current 2 twice. However, ED
To make B f the same value, the triangular wave frequency should be the same.

There is a relationship between these two measurements, and from this calculation, there is a dead time shadow lII? Obtain the measured value of the missing primary resistance r1.

(2) Secondary resistance r2. Measurement of secondary inductance L2 and secondary time constant τ2 In the second south equivalent circuit diagram, current 2 when DC snow pressure is applied
The M pressure equation is 10= i+ -12...---(4) However, LI=1
1+1m, L2=12+1m・11(6). In the Laplace transform of this equation (5), it is Tonaishi. Set the initial value to zero! When +(s) is found, it becomes. The above formula gives the following. Also, R= (L+ 12) and r= (r++
r2) for a typical electric motor is 110KWtt! In machine III, Q/r = 0
．． 031000KWt! The electric motor is p/r=
0.046, and as the capacity becomes smaller, r tends to be smaller and R tends to be smaller, and l is extremely small compared to r.

From this, it is safe to overlook the 82nd term of the characteristic equation Vi in the above equation (8), and assuming that L+ = L2, we get (8). Raitai 1, which is an inverse transformation of this 04 formula. Ge1+
(1)-￥(1-ci-"it")+-e service...Yumer
, -1-r2 However, T = L2/ (-rule "5-) * ・*
(u-a). In this true formula, the second term on the right side is m, Ib
The initial value is generated at the 99th point, ignoring f, and actually rises to this value with a short time constant. Moreover, the above α force equation can also be transformed as follows.

tl(t) = −(1--e-t) ---
--(IJ ha rl-4-r2 From the above E, the Nabewata characteristic diagram when DC pressure E is applied is as shown in Fig. 3, and the final value Ie of current i, α
From the Nishiki formula, re=E. Furthermore, it is assumed that the -order resistance r1 is known by the measurement according to the above-mentioned (Section 11).

Here, the control circuit 11 controls the DC average voltage E ttflI
Similarly to the measurement in item (1), the transistors Tr1 and Tr6f are turned on with a pulse voltage modulated by a triangular wave to be applied to the device 1, and the current L( t, ), 1+(t2)? It is taken in from the current detector 13. In addition, the final value W-Ryuko e-money is taken in.

These current values are 1 (tz), 2 (t2) and the final value. The ratio of
I.

However, ・・・・・・αυr
, -1-r2. From this al, α4 formula, e-÷t, = L (1-y,) -・Fist・@Qa'
)6-7i2= (1-y2) ##fist#-(
14'), and the rise time constant T is calculated from both equations as 1
-y.

T= (t2-tl)/(loge)”
eLf1-y2.

Therefore, the control circuit 11 controls the current L (L), it (%
) and final value. Find the ratio y,,y2f from the above width formula and find the time constant T? Are you looking for this T? Find the constant rXf- from equation 41 (if it is α◆ equation).

Then, the control circuit 11 calculates the secondary resistance r2 from the constant r and the primary resistance r1 according to the above-mentioned equation.

Furthermore, from the resistance r1yr2 and the time constant T, the above (11-
a) According to the formula, the control circuit 11 controls the secondary inductance L
Find 2.

Furthermore, the second-order time constant τ2 is also determined.

"z=Lx/r2'""
''al) Here, the transient current 1t(W, It(
Since the applied voltage to Q has a PWM voltage waveform, ripples also occur in the detected current. In order to remove this ripple and detect 8 degrees well, the transistor Tr as shown in FIG.
i.

The current is sampled at the middle of the inverter output voltage (pulse voltage) by the T'rs reference signal and the gate signal, that is, at the peak of the triangular wave. According to such synchronous samples, if the triangular wave frequency is high enough, changes in the current can be approximated by a straight line, and the peak of the triangular wave can be detected as the average value of the nuclear current. For this purpose, the control circuit 11 uses a triangular wave signal Tri?
Import as sampling timing.

Note that since the -order resistance r1 is measured in a steady state, it may be sampled many times and averaged.

By the above measurements, the control circuit 11Fi-order resistance r
+ #Secondary resistance r2. Secondary inductance L! Find the number of quadratic time frames r2, among which constant r is required in this implementation.
, and fz? Coefficient unit 3. ．． 32 and 62 to control the subsequent vector control'? enable.

In the embodiment, when the vector control device is constituted by a microcomputer or the like, it goes without saying that the control circuit 11 can be incorporated into the control device as a constant measurement program.

In addition, although the embodiment shows a case where it is applied to a vector control bag # using a PWM inverter, the present invention is not limited to this, but can be applied to a slip frequency control device, and the carrier frequency is set to zero (carrier output Stop) $C and the constant can be found from the DC voltage E and current meter detection.

H0 Effects of the Invention As described above, 1. According to the present invention, a DC voltage f is generated from an inverter that serves as a drive power source for an induction motor, and the constant of the induction motor is determined by detecting the output current and voltage of the inverter. Is it possible to apply this to a control device that controls an inverter using all of the foot counts based on this, and automatically measure the constant of an electric machine whose constant is unknown even when the machine is stopped? To make self-tuning reliable and easy, and to automatically set constants. In addition, the constant measurements include the motor wiring, which has the effect of improving practical measurements, settings, and control accuracy.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a vector control device showing one embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of an induction type LD1 machine, FIG. 3 is a current characteristic diagram when a DC voltage is applied to the motor, and FIG. 4 is a wealth i detection timing chart in the present invention. 1... Induction W motive, 21... Inverter king circuit, 2
2...PWM waveform generation circuit, 31 m 32 * 6
2... Coefficient unit, 6... Angular frequency calculation circuit, 7...
Phase voltage calculation circuit, 9... triangular wave generation circuit, 11...
Tuning control circuit, 12...voltage detector, 13.
...Current detector. Fig. 2: The broom is placed in the direction of the turtle. Fig. 3: The mistake of the electric current 411 Take/Shoen

Claims (3)

[Claims] (1) In an induction motor using an inverter as a driving power source, a DC voltage E is generated at the output of the inverter, and the ratio E/I of the output current I of the inverter and the DC voltage E is
The primary resistance r_1 of the induction motor is determined from , and the rising transient current i_1(t_
1), the respective ratios of i_1(t_2) and final current I_e i_1(t_1)/I_e, i_1(t_2)/I_e
Find the rise time constant T of the current I from the following formula r_2/(r_1+r_2)={1-[[i_1(t_
1)]/I_e]}/[e-(1/T)t_1]L_2
=T·[(r_1r_2)/(r_1+r_2)] A method for measuring constants of an induction motor, characterized in that a secondary resistance r_2 and a secondary inductance L_2 of the induction motor are determined according to the formula: =T·[(r_1r_2)/(r_1+r_2)]. (2) The output of the inverter is a pulse voltage of a predetermined frequency, the DC average voltage @E@ of this pulse voltage is detected as the voltage E, and the DC average current @I with respect to the pulse voltage
@ to the current I, transient current i_1(t_1), i_1
2. A method for measuring constants of an induction motor according to claim 1, characterized in that (t_2) and final current I_e are respectively detected. (3) The DC average voltage @E@ is set to two different voltages @E
Switch to @_1, @E@_2, the corresponding voltage @E@_1, @E
Said DC average current @I@_1, @I@_ for @_2
2 is detected, and the following formula r=(@E@_1−@E@_2)/(
2. The method for measuring constants of an induction motor according to claim 2, characterized in that the primary resistance r_1 is determined according to @I@_1-@I@_2).