WO1998043347A1

WO1998043347A1 - Device and method for controlling induction motor

Info

Publication number: WO1998043347A1
Application number: PCT/JP1997/000952
Authority: WO
Inventors: Akira Imanaka; Toshiyuki Kaitani
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 1997-03-24
Filing date: 1997-03-24
Publication date: 1998-10-01
Also published as: JP3320073B2

Abstract

A device and method for controlling induction motor by which an induction motor (1) is controlled based on the predicted change of resistance value of the winding of the motor with the temperature of the motor (1) changes during operation. A resistance measuring instrument (7) measures and outputs the resistance value of the winding and a resistance changing factor computing element (8) computes the difference between the resistance values of the winding measured before and after a first operation cycle and the resistance change coefficient of the winding per unit quantity of the heat generated from the motor (1) during the first operation cycle. Then a resistance change predicting device (9a) outputs the predicted resistance value of the winding predicted from the initial resistance value of the winding of when the motor (1) is started, measured by means of the measuring instrument (7) when a second operation cycle is started, the quantity of the heat generated from the motor (1) during the second cycle, and the resistance change coefficient. A control means (6) controls the motor (1) through an inverter (2) by using the predicted resistance value of the winding.

Description

Description Induction motor control device and induction motor control method

The present invention relates to a control device for an induction motor and a control method for an induction motor, which estimate a change in a winding resistance value due to a temperature change during operation of the induction motor and control the induction motor based on the estimated winding resistance value. About. Background art

As a method for controlling an induction motor with high performance, a vector control method and a sensorless vector control that performs control by estimating the speed are performed. These controls control the equivalent circuit constants of the induction motor, such as primary winding, secondary winding primary and secondary resistance, mutual inductance, primary and secondary leakage inductance, etc. It must be set accurately as a constant, and is measured and set before operation.

However, since the primary and secondary resistances change depending on the temperature of the conductor of the induction motor, even if they are set accurately in advance, there is an error with respect to the true value due to the temperature change of the induction motor. The control accuracy of the actual torque in response to the command deteriorates, and the speed control accuracy of sensorless vector control deteriorates. Furthermore, in the sensorless vector control, if the primary resistance set value has an error with respect to its actual value, not only the control accuracy deteriorates, but also the control itself becomes unstable, and an overcurrent trip may occur. .

In order to solve this problem, Japanese Patent Application Laid-Open No. 7-213001 discloses that in a sensorless inverter device, the secondary resistance of an induction motor at a cold temperature is measured and set as an initial value in a night. During operation, the current and operating time There is disclosed a sensorless integrated circuit device with resistance fluctuation compensation for estimating a secondary resistance fluctuation due to a degree rise and correcting a secondary resistance used for speed calculation.

FIG. 12 is a block diagram of the sensorless receiver with resistance fluctuation compensation described in Japanese Patent Application Laid-Open No. Hei 7-213100, in order to facilitate comparison with the control device of the present invention. It has been rewritten.

In the figure, 1 is an induction motor, 2 is an inverter, 3 is a current detector, 4 is a speed command generator, 6 is a sensorless vector controller, 9 b is a resistance fluctuation estimator, 10 is a switch, 2 0 is a voltage detector, 21 is an initial value measuring device, and 22 is an initial measurement setting device.

The sensor 2 receives a switching signal output from the sensorless vector controller 6 and outputs a voltage corresponding to the switching signal to the induction motor 1 via the current detector 3 and the voltage detector 20. I do.

The switch 10 closes to the initial value measuring device 21 only at the start of operation immediately after the control power is turned on, and outputs the switching signal output from the initial value measuring device 21 to the inverter 2. According to the switching signal of the initial value measuring device 21, a DC voltage is averagely applied to the induction motor 1 from the inverter 2. Then, after a certain period of time, the current の of the induction motor 1 is measured by the current detector 3, an initial value S 0 of the temperature rise of the induction motor 1 is obtained from the equation (1), and output to the resistance fluctuation estimator 9b. Here, 1x0 is a measured current value of the secondary resistor R2n by the same method when the temperature of the induction motor 1 is the same as the ambient temperature, and K1 is a conversion coefficient between temperature and current.

The resistance fluctuation estimator 9b inputs the current I, which is the output of the current detector 3, and estimates the temperature rise 0 of the induction motor 1 by the equation (2), and further sets the initial measurement. Using the R2n input from the sensor 22, the secondary resistance fluctuation is estimated by the equation (3), and the corrected secondary resistance R2x is output to the sensorless vector controller 6. Where K is the conversion gain and T is the time constant. e = KI ² {l / (l ₊ ST)}... (2)

R2 _x = (l ₊ KW) R2 _n (3) Sensorless vector controller 6 is the speed command value ωm *, which is the output of speed command generator 4, and the output of current detector 3. Input the current I, the voltage V output from the voltage detector 20 and the modified secondary resistance R2x output from the resistance fluctuation estimator 9b.The secondary of the induction motor 1 set internally is also input. The speed of the induction motor 1 is controlled using the set value other than the resistance and the control gain so as to follow the command value ωm *.

Since the conventional induction motor control device was configured as described above, it was necessary to set the thermal resistance, thermal time constant, and the like of the induction motor in advance. In particular, these heat-related constants vary depending on the motor to be driven, and also vary depending on installation conditions, etc., so it is necessary to measure and set them in advance in actual use conditions. It is difficult to apply it to motors in general, and to protect the induction motor from overheating, it is necessary to install a thermocouple inside the motor to measure the temperature of the induction motor. Had a special specification.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. The present invention estimates the resistance change while calculating the resistance change characteristic of an induction motor in an actual use state, and estimates the speed based on the result and facilitates the calculation. An object of the present invention is to provide an induction motor control device and an induction motor control method capable of favorably controlling an induction motor without previously setting a thermal resistance, a thermal time constant, and the like of the induction motor in order to perform the correction. Disclosure of the invention

In the control device for an induction motor according to the present invention, the resistance measuring means measures a winding resistance value of the induction motor, and the resistance change coefficient calculating means calculates a difference between a winding resistance value measured before and after the first operation cycle. Based on the value related to the amount of heat generated by the induction motor during the first operation cycle, the resistance change coefficient of the winding resistance per unit amount of this value is calculated. It was estimated based on the starting winding resistance measured at the start of the second operation cycle following the first operation cycle, the value related to the calorific value of the induction motor during the second operation cycle, and the resistance change coefficient. Since the estimated winding resistance value is output, and the control means controls the chamber for driving the induction motor using the estimated winding resistance value, even if the heating value of the induction motor changes, the installation condition may be different, Even for induction motors with different thermal time constants It becomes possible to estimate the resistance fluctuation that changes with the operation cycle, and it is possible to accurately control the speed of the induction motor using the estimated resistance.

Further, in the control device for the induction motor of the present invention, the resistance change coefficient calculation means calculates a value related to a calorific value of the induction motor generated during the first operation cycle based on a current value supplied to the induction motor. Since the resistance fluctuation estimating means calculates a value related to the calorific value of the induction motor generated during the second operation cycle based on the current value supplied to the induction motor, the induction motor changes due to a change in the current value in the operation cycle. Even if the calorific value of the motor changes, the resistance fluctuation can be estimated, and the speed of the induction motor can be controlled accurately using the estimated resistance value.

Further, in the induction motor control device according to the present invention, the resistance change coefficient calculating means calculates a value related to a calorific value of the induction motor generated during the first operation cycle based on a torque command value instructed to the induction motor. Then, since the resistance fluctuation estimating means calculates a value related to the heat generation amount of the induction motor generated during the second operation cycle based on the torque command value instructed to the induction motor, the change of the command torque in the operation cycle is calculated. Even if the amount of heat generated by the induction motor changes due to the development, the resistance fluctuation can be estimated, and the speed of the induction motor can be accurately controlled using the estimated resistance value. Further, in the induction motor control device according to the present invention, the resistance fluctuation estimating means may be configured to start up by measuring the stop-time winding resistance measured by the resistance measuring means at the time of stopping the first operation cycle at the time of starting the second operation cycle. Since the estimated winding resistance value in the second operation cycle is output as the time winding resistance, the resistance measuring means does not need to measure the winding resistance at startup in the second operation cycle. The time required is shorter.

Further, in the induction motor control device of the present invention, the resistance measuring means measures a winding resistance value of the induction motor, and the resistance change coefficient calculating means calculates a difference between the winding resistance values measured before and after the first operation cycle. From this value and the value related to the heat value of the induction motor generated during the first operation cycle, the resistance change coefficient of the winding resistance per unit amount is calculated from this value, and the resistance characteristic storage means changes the resistance change. The relationship between the coefficient and the winding resistance is stored, and the resistance measuring means refers to the relationship stored based on the starting winding resistance measured at the start of the second operation cycle following the first operation cycle. The resistance change estimation means outputs the resistance change coefficient output from the resistance characteristic storage means on the basis of the winding resistance value at start-up, and the value related to the heat generation amount of the induction motor during the second operation cycle. From the estimated winding resistance value and output Since the means controls the induction motor driving the induction motor using the estimated winding resistance value, the resistance fluctuation estimating means uses the resistance change coefficient output from the resistance characteristic storage means and the start-up time measured at the start of the operation cycle. The resistance fluctuation can be estimated based on the winding resistance, and the thermal resistance and thermal time constant are not set beforehand. Even if there is a large difference, the winding resistance can be estimated well.

In the control device for an induction motor according to the present invention, the resistance characteristic storage means stores the current value during the first operation cycle as a parameter and calculates a resistance change coefficient and a winding resistance value. Since the resistance measuring means outputs the resistance change coefficient corresponding to the starting winding resistance measured at the start of the second operation cycle with reference to the current value of the second operation cycle, the resistance measurement means outputs the resistance. The characteristic storage means uses the resistance change coefficient characteristic data stored corresponding to the current value closest to the current value of the operation cycle out of the stored winding resistance value and resistance change coefficient, and A resistance change coefficient is output based on the winding resistance measured at startup, and a resistance change coefficient suitable for resistance fluctuation due to multiple load states of the induction motor can be set. Regardless, the winding resistance can be estimated with high accuracy.

Further, in the induction motor control device of the present invention, the resistance characteristic storage means stores the resistance change coefficient calculated by the resistance change coefficient calculation means in the first operation cycle and the winding resistance measured by the resistance measurement means at that time. Is stored as a function approximation, a resistance change coefficient closer to the actual change can be obtained by referring to the resistance change coefficient from the winding resistance at the start of the operation cycle.

Also, in the induction motor control device of the present invention, the resistance change coefficient calculating means may include an estimated winding resistance estimated at the time of stopping the second operation cycle and a resistance at the time of stoppage measured by the resistance measuring means at the time of stopping the second operation cycle. The relationship between the winding resistance and the resistance change coefficient stored in the resistance characteristic storage means is corrected when these differences exceed a predetermined value. Even if a temperature difference between the induction motor temperature and the ambient temperature or a change in the flow rate of the surrounding air, etc., due to the environmental change of the winding, etc., occur, the winding resistance value and the resistance change coefficient stored in the resistance characteristic storage means. Can be corrected to match the actual state, and the resistance fluctuation can be estimated well.

Further, in the induction motor control device of the present invention, the temperature estimating means stores in advance the relationship between the winding temperature and the winding resistance of the induction motor, and the estimated winding resistance outputted by the resistance change coefficient calculating means. From the relationship between the winding temperature and the winding resistance based on Since the temperature of the line is estimated, the temperature of the induction motor can be estimated without setting the thermal resistance and the thermal time constant of the induction motor in advance.

In the induction motor control device according to the present invention, the temperature estimating means stores the resistance value of the wiring from the inverter to the induction motor in advance, and the wiring of the wiring is determined from the primary winding resistance value output from the resistance measuring means. Since the temperature of the primary winding is estimated based on the value obtained by subtracting the resistance value, the primary winding resistance value is regarded as the wiring resistance value even if the wiring length from the inverter to the induction motor is relatively long. The temperature of the primary winding of the induction motor can be estimated separately.

Further, in the control device for the induction motor of the present invention, the temperature estimating means outputs a stop signal for stopping the operation of the induction motor to the control means when the temperature of the winding exceeds a predetermined value, and the control means Since the operation is stopped in the evening, it is possible to prevent the induction motor from overheating without installing a thermocouple inside the motor.

Further, in the control device for the induction motor of the present invention, the operation mode setting means may be configured such that, before the first and second operation cycles, each of the predetermined operation cycles in which the resistance change coefficient calculation means repeats the set number of times. From the difference between the winding resistance measured by the resistance measuring means at the start and stop of the operation cycle and the value related to the calorific value of the induction motor generated in each operation cycle, the resistance of the winding resistance per unit quantity The change coefficient is calculated for each operation cycle, and the relationship between the resistance change coefficient and the winding resistance value for each operation cycle is stored in the resistance characteristic storage means. The relationship between the change coefficients is stored in the resistance characteristic storage means in advance, and in the second operation cycle, the more appropriate relationship between the winding resistance value and the resistance change coefficient is stored, so that the resistance variation can be estimated well. Become so.

In addition, the control method of the induction motor of the present invention is based on the difference between the winding resistance measured before and after the operation cycle and the value related to the calorific value of the induction motor generated during the operation cycle. Calculates the resistance change coefficient of winding resistance per unit quantity Then, at the start of the next operation cycle, the winding resistance at startup is measured, and based on the winding resistance at startup, an estimation is made from the resistance change coefficient and the value related to the calorific value of the induction motor during the operation cycle. Since the winding resistance is output and the induction motor is controlled based on the estimated winding resistance, the winding resistance is measured when the operation cycle is stopped. Even if the calorific value changes, it is possible to estimate the resistance fluctuation that changes with the operating cycle even for induction motors with different installation conditions and different thermal time constants. Speed can be controlled.

In addition, the control method of the induction motor of the present invention is based on the difference between the winding resistance measured before and after the operation cycle and the value related to the calorific value of the induction motor generated during the operation cycle. Calculates the resistance change coefficient of the winding resistance per unit amount of, stores the relationship between the winding resistance and the resistance change coefficient, measures the winding resistance at startup at the start of the next operation cycle, and calculates the winding resistance at startup. The resistance change coefficient corresponding to the wire resistance is obtained with reference to the relationship between the winding resistance and the resistance change coefficient, and based on the starting winding resistance, the resistance change coefficient corresponding to the starting winding resistance is calculated based on the starting winding resistance. The estimated winding resistance estimated from the value related to the calorific value of the induction motor is output, and the induction motor that drives the induction motor is controlled based on the estimated winding resistance. Since the winding resistance value at stop is measured, Based on the start-up winding resistance measured at the start of the operation, the resistance change coefficient corresponding to the start-up winding resistance of the operation cycle is determined with reference to the relationship between the winding resistance and the resistance change coefficient. The resistance fluctuation can be estimated using the value related to the heat value during the cycle, without setting the thermal resistance, thermal time constant, etc. in advance, and the resistance at the time of start-up Even if there is a large difference from the resistance at startup, the winding resistance can be estimated well. BRIEF DESCRIPTION OF THE FIGURES 1 to 11 are diagrams showing a preferred embodiment according to the present invention. FIG. 1 is a block diagram showing a control device for an induction motor according to a first embodiment of the present invention. FIG. 3 is a flowchart showing a control method of the induction motor control device shown in FIG. 1, FIG. 3 is a block diagram of the induction motor control device according to the second embodiment of the present invention, and FIG. FIG. 5 is an explanatory diagram showing the winding resistance value and the resistance change coefficient of the motor. FIG. 5 is an explanatory diagram showing the relationship between the winding resistance value and the resistance change coefficient stored in the resistance characteristic storage unit 11 shown in FIG. 3, and FIG. Fig. 3 is a flowchart showing a control method of the induction motor control device shown in Fig. 3, and Fig. 7 shows a winding resistance value and a resistance change coefficient when a current value of a general induction motor is a parameter. Fig. 8 shows the winding resistance and resistance stored in the resistance characteristic storage 11a shown in Fig. 9. FIG. 9 is a block diagram of an induction motor control device of another embodiment according to the second embodiment of the present invention, and FIG. 10 is a control of the induction motor according to the third embodiment of the present invention. FIG. 11 is a block diagram showing a device, FIG. 11 is a block diagram showing a control device for an induction motor according to a fourth embodiment of the present invention, and FIG. 12 is a block diagram showing a control device for a conventional induction motor. BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1

FIG. 1 is a block diagram showing one embodiment of a control device for an induction motor according to the present invention. In the figure, 1 is an induction motor, 2 is an inverter that supplies voltage to the induction motor 1, 3 is a current detector that detects the current of the induction motor 1, 4 is a speed command generator that generates a speed command, 5a Is a tuning controller that controls the tuning by inputting a speed command output from the speed command generator 4, 6 is a sensorless vector controller that controls the induction motor 1, and 7 is an induction motor when starting and stopping. This is a resistance measuring instrument that measures the primary and secondary resistance of the primary and secondary windings. Here, the secondary winding includes the cage winding Shall be. 8 is a resistance change coefficient calculator for calculating the resistance change coefficient of the induction motor 1 based on the outputs of the current detector 3 and the resistance measurement device 7, and 9a is the current detection device 3, the resistance measurement device 7, and the resistance. A resistance fluctuation estimator that estimates the resistance fluctuation of the induction motor 1 based on the output of the change coefficient calculator 8, and 10 is a circuit closed to the resistance measuring device 7 when starting and stopping, and a sensorless vector controller during operation. This is a control switch that closes to the 6 side, and is controlled by the tuning controller 5a. Next, the operation will be described with reference to the drawings. First, at start-up when the speed command ω m * is input from the speed command generator 4, the tuning controller 5a operates so as to close the control switch 10 to the resistance measuring device 7 side. The switching signal output from 7 enables the voltage to be output from the chamber 2 to the induction motor 1. Further, a resistance measurement start signal from the tuning controller 5a is input to the resistance measurement device 7, and the resistance measurement device 7 starts measuring the primary and secondary resistance values of the induction motor 1.

Here, the resistance measurement performed by the resistance measuring device 7 may be performed by a method described in, for example, JP-A-6-79380. That is, a DC current _ID is generated in the output of the inverter 2 in a step-like manner, and the final value Vl (∞) of the primary voltage VI of the induction motor 1 and the ratio of the DC current Vl (∞) / _ID to 1 The secondary resistance R1 is obtained, and the transient voltage Vl (tl), Vl (t2) and the final value Vl (oo) of the primary voltage VI due to the DC current I _D are obtained from the induction motor 1 by the equation (4). The next-time constant is determined as 2, and the secondary resistance R2 is determined from equation (5) using the time constant as 2. Note that 2 = L2 / R2, and L2 is a constant value even when the temperature changes, so that L2 can be accurately set in advance. t2-tl

τ2

(Vl (tl)-Vl (∞) \ (4) lo,

\ Vl (t2)-Vl (∞) J Vl {tl)-Vl {∞) = I _D R2e ^Tl ... (5) Here, in order to generate the DC current ID at the output of the inverter 2 in a step-like manner, normal vector control or the like is used. A generally used current controller may be provided inside the resistance measuring device 7 and a step-like current command may be given to the chamber 2.

In order to obtain the final value Vl (∞) of the primary voltage VI, since the secondary time constant of the ordinary induction motor 1 is several tens to several hundreds of milliseconds, the time is several times as long as that. Even if the value of several hundred msec to several sec is used as the final value Vl (∞) of the primary voltage VI, the measurement can be completed in a short time with almost no error. Next, when the resistance measurement device 7 completes the measurement of the primary resistance and the secondary resistance, a resistance measurement completion signal is sent to the tuning controller 5a, and at the same time, the resistance change coefficient calculator 8 and the resistance change The measurement result is output to the estimator 9a. When the resistance measurement completion signal output from the resistance measurement device 7 is input, the tuning controller 5a operates to close the control switch 10 to the sensorless vector controller 6 side, and the sensorless vector The operation of the induction motor 1 is started by the switching signal output from the torque controller 6.

After that, a stop command is input from the speed command generator 4 to the sensorless vector controller 6 via the tuning controller 5a, and when the induction motor 1 decelerates and stops, the sensorless vector controller 6 The stop completion signal is output to the tuning controller 5a. The tuning controller 5a outputs a resistance measurement start signal to the resistance measurement device 7 in response to the input of the stop completion signal, and the resistance measurement device 7 receives the resistance measurement start signal again and operates in the same manner as when starting. As a result, measurement of the primary resistance and the secondary resistance of the induction motive 1 is started.

When the resistance measuring device 7 completes the measurement of the primary resistance and the secondary resistance, A resistance measurement completion signal is sent to the uning controller 5a, and at the same time, the measurement result is output to the resistance change coefficient calculator 8. The resistance change coefficient calculator 8 includes a control signal output from the tuning controller 5a, the current I of the induction motor 1 output from the current detector 3, and the induction motor input from the resistance measurement device 7. Input the measured values of the primary and secondary resistances at the start and immediately after the stop in Step 1, and integrate the difference between the measured primary and secondary resistances at the start and immediately after the stop during the operation time of the induction motor. Divide by I ² t (time integral of current squared value), and change coefficient of primary resistance and secondary resistance per unit quantity (I ² t = l) obtained by equations (6) and (7) K Rl and K R2 are calculated and output to the resistance fluctuation estimator 9a. This is because the temperature rise of the winding of the induction motor 1 is almost proportional to the resistance loss caused by the current flowing through the winding resistance of the induction motor 1, and the calorific value is proportional to the square of the current I. That's why.

^ R1 (immediately after stopping) One R1 (when starting)

m ₂ R2 (immediately after stopping) – H2 (at startup)…, ₇ )

M

From the next startup, the control signal output from the tuning controller 5a, the current I of the induction motor 1 output from the current detector 3, and the input from the resistance measurement device 7 are output by the resistance fluctuation estimator 9a. The measured values of the primary resistance and secondary resistance of the induction motor 1 at startup and the change in primary resistance and secondary resistance per unit quantity (I ² t = 1) output from the resistance change coefficient calculator 8 Enter the coefficients K Rl and K R2, and use the measured values at startup of the primary and secondary resistors as the initial values, and use the equations (8) and (9) to estimate the primary and secondary resistance Rl *, Calculates R2 * and outputs it to sensorless vector controller 6. Rl * = KRl ^ I ² t + Rl (at startup)... (8)

R2 * + R2 (at startup) · · · (9)

The sensorless vector controller 6 includes a speed command value ωm * output from the speed command generator 4 via the tuning controller 5a, a current I output from the current detector 3, and a resistance fluctuation estimator. 9 Input the primary resistance and secondary resistance estimated values R1 * and R2 * output from a, and use the constants and control gain of the induction motor 1 set internally to determine the speed of the induction motor 1 Control to follow the value ωm *.

A control method of the above-described induction motor control device will be described with reference to a flowchart shown in FIG. First, in step S11, the change coefficients K R1 and K R2 of the primary resistance and the secondary resistance are initialized to appropriate values. K Rl and K R2 may be zero if an error in resistance estimation is allowed only during the first operation.

Next, in step S12, the tuning controller 5a determines whether or not the operation start signal is given, and waits until the operation start signal is given. When the operation start signal is given, in step S13, a direct current is supplied to the induction motor 1 by the inverter 2 and the resistance measuring device 7 measures the primary resistance and the secondary resistance.

Next, in step S14, the operation shifts to the actual operation cycle of the normal operation mode, and the operation of the induction motor 1 is started. In step S14, the resistance value measured in step S13 is used as an initial value, and K Rl and K R2 (the initial value set in step S11 only for the first time) and the induction motor determined last time are used. estimating the variation of the primary resistance and secondary resistance during actual operation cycle operation as the current I from the ^{K Rl Σ I 2 t, K} R2 Σ I 2 t flowing in, the primary resistance and the estimated The sensorless vector controller 2 performs control using the secondary resistance. In step S15, a stop signal is given to determine whether induction motor 1 has stopped. Is determined by the tuning controller 5a, and the process returns to step S14 while the induction motor 1 is operating. If the stop signal is given and the induction motor 1 stops, in step S16, the direct current is again supplied to the induction motor 1 by the inverter 2 and the resistance measuring device 7 measures the primary resistance and the secondary resistance. .

Further, in step S17, the difference between the primary resistance and secondary resistance at startup measured in step S13 and the primary resistance and secondary resistance at shutdown measured in step S16 is calculated by the induction motor 1. Divided by 2I ² t (time integral of current squared value) integrated during the operation time of the actual operation cycle of, and the change coefficient of primary resistance and secondary resistance per unit quantity (i ² t = l) Find K Rl and K R2. This completes a series of operations, returns to step S12 again, and waits until the next operation start signal is given. *

When the induction motor 1 is controlled by the above-described method, the resistance fluctuation estimator 9a estimates the primary resistance and the secondary resistance, which change every moment during the actual operation cycle, and the sensorless vector controller 6 controls the induction motor 1 The speed is controlled precisely so that the speed follows the command value ωm *.

As described above, according to the present invention, the resistance change coefficient calculation for calculating the resistance change coefficient based on the resistance value measured by the resistance measuring device 7 immediately after the start and immediately after the stop and the current detected by the current detector 3 The resistance fluctuation is estimated based on the current detected by the current detector 3, the resistance at start-up measured by the resistance measuring instrument 7, and the resistance change coefficient calculated by the resistance change coefficient calculator 8. A resistance fluctuation estimator 9a is provided to estimate the resistance fluctuation of the induction motor 1 without previously setting the thermal resistance, thermal time constant, and the like.

Further, the resistance change coefficient calculator 8 calculates the difference between the resistance value at the start-up measured by the resistance measuring device 7 and the resistance value immediately after the stoppage during the operation time of the induction motor 1. Divide by the time integral of the square of the detected current, calculate the resistance change coefficient as the amount of resistance change per unit heat, and calculate the resistance change The estimator 9a is obtained by multiplying the resistance value at the time of startup measured by the resistance measuring device 7 as an initial value, and multiplying the time integral value of the square of the current detected by the current detector 3 by the resistance change coefficient. Is configured to calculate the resistance value as a resistance variation value, so that even if the value of the current flowing through the induction motor 1 changes, the resistance variation corresponding thereto can be estimated.

If the stop time is sufficiently smaller than the thermal time constant of the induction motor 1, the difference between the resistance measured immediately after the stop and the resistance at the next start is small. Almost no error occurs. In other words, a stop time measuring device that counts the stop time of the induction motor 1 is provided inside the tuning controller 5a, and when the stop time is sufficiently shorter than the thermal time constant of the induction motor 1, the start time is measured by the resistance measurement device 7. May be omitted, and the resistance measured immediately after stopping may be used as the resistance at the next startup.

In addition, when the induction motor 1 is stopped, a timer is provided inside the tuning controller 5a, and the resistance value is measured by the resistance measuring device 7 at an appropriate interval short enough to the thermal time constant of the induction motor 1, When the start signal is input, the resistance value at the time of the stop measured immediately before may be used instead of the resistance measurement at the start by the resistance measuring device 7.

This has the effect that the resistance measurement at startup can be omitted and the startup can be performed quickly.

Further, in the first embodiment, the resistance change coefficient calculator 8 and the resistance change estimator 9a use the current detection to calculate the change coefficient of the primary resistance and the secondary resistance and to calculate the primary resistance and the secondary resistance. The square value of the current of the induction motor 1 detected by the heater 3 was used, but if the current command value and the torque command value were created inside the sensorless vector controller 6, those square values were used. It may be used as a unit amount. Also, a means for estimating or detecting an amount approximately proportional to the output torque of the induction motor is provided inside the sensorless vector controller 6 or on the load side of the induction motor. If provided, the squared values of those outputs may be used as unit quantities. Further, in this first embodiment, the resistance change coefficient calculator 8, startup and stop immediately after the primary resistance and secondary resistance measurement of the difference obtained by integrating into the induction motor operation time sigma I ² t (current 2 (Time integral value of the power value), and the change coefficients K R1 and K R2 of the primary resistance and the secondary resistance per unit quantity (I ² t = l) obtained by equations (6) and (7). Was calculated. This is because most of the heat generated from the induction motor 1 is generated by the current flowing through the winding resistance of the induction motor 1, and the amount of heat generated is proportional to the square of the current I. However, when a cooling device such as a self-cooling fan or a forced fan mounted on the shaft of the induction motor 1 is provided, the temperature of the standard induction motor 1 does not rise under almost no load condition. Confirmed by experiment. Therefore, when calculating the change coefficients K Rl and K R2 of the primary resistance and the secondary resistance by the resistance fluctuation estimator 9a, the temperature rise of the induction motor 1 is calculated from the square of the current I to the no-load current I 0. The calculation may be performed by equations (10) and (11) as proportional to the amount obtained by subtracting the power.

R1 (immediately after stopping)

KR1 = one R1 (at startup)

S (10) (/ ^2- / o ² )

R2 (immediately after stopping) One R2 (when starting)

KR2 (1 1)

When K R1 and K R2 are calculated by Eqs. (10) and (11), the resistance fluctuation estimator 9a calculates the primary resistance and the secondary resistance at the time of startup measured by the resistance measurement instrument 7. As the initial value, the primary resistance and the secondary resistance estimation values Rl * and R2 * may be calculated from the equations (12) and (13) and output to the sensorless vector controller 6.

R1 * = ΚΝΪ ^ (I ² -I0 ² ) t + R1 (at startup) ··· (1 2) R2 * = KR2 ^ (I ² -I ² ) t + R2 (at startup)... (1 3)

Thereby, there is an effect that the resistance fluctuation can be estimated as a value closer to the actual resistance value.

When the current of the induction motor 1 is almost constant, the resistance change coefficient calculator 8 omits the calculation of the time integral value of the square of the current, and starts the induction motor 1 input from the resistance measuring device 7. Calculate the primary and secondary resistance change coefficients K Rl and K R2 as the resistance change per unit time by dividing the difference between the primary and secondary resistances at the time and immediately after the stop by the operation time from start to stop. May be. In this case, the resistance fluctuation estimator 9a multiplies the change coefficients K Rl and K R2 of the primary resistance and the secondary resistance calculated as the amount of change per unit time by the elapsed time from the start, and changes the resistance. It may be calculated as a quantity.

Thus, there is an effect that the resistance fluctuation can be estimated with a small amount of calculation. Furthermore, in the first embodiment, the primary resistance and the secondary resistance are measured by the resistance measuring device 7, and the resistance change coefficients K R1 and K R1 of the primary resistance and the secondary resistance are measured by the resistance change coefficient calculator 8. R2 is calculated, and the primary and secondary resistance estimation values Rl * and R2 * are calculated by the resistance fluctuation estimator 9.However, the primary and secondary resistances can be calculated independently. It may be configured to estimate only one of them.

In other words, if the sensorless vector controller 6 uses both the primary resistance and the secondary resistance, both are estimated as described above.If only the primary resistance is used, the resistance measurement device 7 and the resistance change coefficient calculation are used. In the case where only the primary resistance is estimated using only the primary resistance in the resistor 8 and the resistance variation estimator 9, only the secondary resistance is estimated when only the secondary resistance is used.

With the above configuration, it is possible to measure only the resistance value necessary for the control calculation of the induction motor 1, simplify the resistance measurement with the resistance measuring device 76, and estimate the resistance change coefficient calculator 8 and the resistance variation estimation. It can be said that the operation in unit 9a can be simplified. Has the effect.

In addition, assuming that the primary resistance and the secondary resistance change in the same way, only the primary resistance value is measured by the resistance measuring instrument 7 and the measured primary resistance value is used by the resistance change coefficient calculator 8 to calculate the primary resistance. The resistance change coefficient K R1 of the resistor may be calculated and used as the resistance change coefficient K R2 of the secondary resistor. Further, the reverse may be applied.

Embodiment 2

FIG. 3 is a block diagram showing a control device for an induction motor according to a second embodiment of the present invention. In FIG. 3, 1 is an induction motor, 2 is an inverter that supplies voltage to the induction motor 1, 3 is a current detector that detects the current of the induction motor 1, 4 is a speed command generator that generates a speed command, 5 b is a tuning controller that controls the tuning by inputting a speed command output from the speed command generator 4, 6 is a sensorless vector controller for controlling the induction motor 1, and 7 is at startup It is a resistance measuring device that measures the primary and secondary resistance of the induction motor 1 when stopped. 8 is a resistance change coefficient calculator for calculating the resistance change coefficient of the induction motor 1 based on the output of the current detector 3 and the resistance measurement device 7, and 11 is the resistance change coefficient calculator of the resistance measurement device 7. 9a is a resistance characteristic memory which stores the relationship between the resistance change coefficient and the resistance value by inputting the output and the resistance change coefficient, and 9a is a resistance characteristic memory of the induction motor 1 based on the output of the current detector 3, the resistance measuring device 7 and the resistance characteristic memory 11. A resistance change estimator 10 for estimating the resistance change.10 is a control switch that closes to the resistance measurement device 7 when starting and stopping and closes to the sensorless vector controller 6 during operation. Controlled by tuning controller 5b.

Next, the operation of the control device for an induction motor according to the second embodiment will be described. In the first embodiment, the resistance change estimator 9a uses the resistance change coefficient calculator 8 to calculate the resistance change coefficients K R1 and K R2 calculated using the resistance measurement values immediately before the start and immediately after the stop. In the second embodiment, the resistance change coefficient with respect to the resistance value is stored in the resistance characteristic storage unit 11, and the stored resistance is stored. The resistance fluctuation is estimated by the resistance fluctuation estimator 9a using the resistance change coefficients K Rl and K R2.

Here, assuming that the current I is flowing through the induction motor 1, it is considered that the heat generated from the induction motor 1 is proportional to the square of I per unit time due to its resistance. However, since heat is radiated from the induction motor 1 to the surroundings, the temperature rise of the induction motor 1 exhibits a first-order lag characteristic, and as a result, the primary resistance and the secondary resistance of the induction motor 1 and the primary resistance The change coefficients K Rl and K R2 of the resistance and the secondary resistance have characteristics as shown in FIG. Fig. 4 (a) illustrates the relationship between the value related to the calorific value of the induction motor and the resistance value, and Fig. 4 (b) illustrates the relationship between the value related to the calorific value of the induction motor and the resistance change coefficient. . When the current of the induction motor 1 is constant, the horizontal axis in FIG. 4 can be read as time. FIG. 5 shows the characteristics of FIG. 4 as a relationship between the resistance value and the resistance change coefficient. Therefore, the resistance change coefficients of the primary resistance and the secondary resistance are calculated for each actual operation cycle and stored in the resistance characteristic memory 11 according to the same operating principle as in the first embodiment. By calling the resistance change coefficients K Rl and K R2 as functions, it is possible to set a coefficient that is more suitable for the actual resistance change.

First, when the speed command ω is input from the speed command generator 4 to the tuning controller 5, the tuning controller 5b closes the control switch 10 to the resistance measuring device 7 side, and furthermore, the resistance measuring start signal Is output to the resistance measuring instrument 7. When the resistance measurement device 7 receives the resistance measurement start signal from the tuning controller 5b, the resistance measurement device 7 starts measuring the primary and secondary resistance values of the induction motor 1. Note that the resistance measuring device 7 measures the resistance value in the same manner as the method described in the first embodiment.

Next, when the resistance measurement device 7 completes the measurement of the primary resistance and the secondary resistance, it outputs a resistance measurement completion to the tuning controller 5b, and at the same time, performs the resistance change coefficient operation. The measurement result is output to the calculator 8, the resistance characteristic storage unit 11, and the resistance fluctuation estimator 9a. When the resistance measurement completion signal output from the resistance measurement device 7 is input, the tuning controller 5b operates to close the control switch 10 to the sensorless vector controller 6 side, and the sensorless vector The operation of the induction motor 1 is started by the switching signal output from the controller 6.

After that, a stop command is input from the speed command generator 4 to the sensorless vector controller 6 via the tuning controller 5b, and when the induction motor 1 decelerates and stops, the stop completion signal is output to the tuning controller 5 Output to b. The tuning controller 5b outputs a resistance measurement start signal to the resistance measurement device 7 in response to the input of the stop completion signal, and when the resistance measurement start signal is input, the resistance measurement device 7 returns to the same state as when the resistance measurement device 7 is started. The measurement of the primary resistance and secondary resistance of the induction motor 1 is started by the method described in (1).

Further, when the resistance measuring device 7 completes the measurement of the primary resistance and the secondary resistance, a resistance measurement completion signal is sent to the tuning controller 5b, and the measurement result is simultaneously sent to the resistance change coefficient calculator 8. Is output. The resistance change coefficient calculator 8 includes a control signal output from the tuning controller 5b, a current I of the induction motor 1 output from the current detector 3, and an induction motor input from the resistance measuring device 7. Enter the measured values of the primary resistance and the secondary resistance at the start and immediately after the stop of Step 1 and use the same method as described in Embodiment 1 to determine the primary resistance and the unit resistance (I ² t = 1). Calculate the secondary resistance change coefficients K Rl and K R2 and output them to the resistance characteristic storage 11.

The resistance characteristic storage 11 stores the resistance corresponding to the resistance closest to the resistance measured at startup measured by the resistance measurement device 7 among the resistance values and the resistance change coefficients stored in the resistance characteristic storage Π. The change coefficient is output to the resistance fluctuation estimator 9a. The resistance change estimator 9a inputs the resistance change coefficient output from the resistance characteristic storage 11, and performs the same operation as in the first embodiment to obtain the primary resistance and the secondary resistance. The estimated value is calculated and output to the sensorless vector controller 6. By repeating this series of operations, the resistance change memory 11 stores the resistance change coefficients K Rl and K R2 for a plurality of resistance values, and a more detailed relationship between the resistance value and the resistance change coefficient is stored. Stored. Further, the relationship between the accumulated resistance value and the resistance change coefficient is used for the resistance estimation by the resistance variation estimator 9a, so that more accurate resistance estimation can be realized.

A control method of the control device for the induction motor according to the second embodiment will be described with reference to a flowchart shown in FIG. First, in step s101, the tuning controller 5b determines whether or not the operation start signal is given, and waits until the operation start signal is given. When the operation start signal is given, in step S102, a direct current is supplied to the induction motor 1 by the inverter 2 and the resistance measurement device 7 measures the primary resistance and the secondary resistance. Next, in step S103, the resistance change coefficients K Rl and K R2 stored in the resistance characteristic storage unit 11 are referred to using the resistance value measured in step S102. Further, in step S104, the operation shifts to the actual operation cycle, which is the normal operation mode, and the operation of the induction motor 1 is started. In step S104, the resistance measured in step S102 is used as an initial value, and KR1 and KR2 referenced in step S103 and the current I flowing through the induction motor are calculated as K Assuming that Rl 、 I ² t and K R2 ∑ I ² t, the fluctuations of the primary resistance and the secondary resistance during the operation of the actual operation cycle are estimated, and the sensorless operation is performed using the estimated primary resistance and the secondary resistance. The vector controller 6 controls the room 2.

In step S105, the tuning controller 5b determines whether the stop signal is given and the induction motor 1 is stopped, and returns to step S104 while the induction motor 1 is operating. When the stop signal is given and the induction motor 1 is stopped, the primary resistance and the secondary resistance of the induction motor 1 are measured again by the chamber 2 at step S106. Further, in step S107, step S1 02 The difference between the primary resistance and secondary resistance at startup measured at step 2 and the primary resistance and secondary resistance at stop measured at step S106 is the operating time of the induction motor 1 in the actual operation cycle. Divide by ∑I ² t (time integral of current squared value) integrated in the equation to find the primary and secondary resistance change coefficients K Rl and K R2 per unit quantity (i ² t = 1) . Next, in step S108, the latest data calculated in step S107 is added to the relational data of the resistance change coefficient with respect to the resistance value stored in the resistance characteristic storage unit 11, or the latest data is added. To perform the conventional data overnight correction. This completes a series of operations, returns to step S101 again, and waits until the next operation start signal is given.

As described above, according to the control device for an induction motor according to the second embodiment, the resistance is determined based on the resistance value measured by the resistance measuring device 7 immediately after the start and immediately after the stop and the current detected by the current detector 3. The resistance change coefficient calculator 8 for calculating the change coefficient, the resistance value measured by the resistance measuring device 7 and the resistance change coefficient calculated by the resistance change coefficient calculator 8 are input, and the relation between the resistance change coefficient and the resistance value is calculated. And a resistance change at the time of start-up measured by the current measuring device 3 and the resistance measuring device 7 and an output from the resistance characteristic storing device 11. Since the resistance fluctuation estimator 9a for estimating the resistance fluctuation based on the coefficient is provided, the resistance at start-up can be changed to the previous resistance without setting the thermal resistance, thermal time constant, etc. in advance. If there is a big difference This also has the effect that the resistance fluctuation of the induction motor 1 can be satisfactorily estimated.

In the induction motor control device according to the second embodiment, the relationship between the resistance change coefficients K Rl and K R2 corresponding to the resistance value is stored and accumulated, and the resistance is estimated using the stored relationship. Further, the current detected by the current detector 3 is stored as a parameter and the relationship between the resistance change coefficients K Rl and K R2 corresponding to the resistance values is stored and accumulated. The resistance is estimated by referring to the relationship between the resistance change coefficients K Rl and K R2 corresponding to the values. May be implemented.

As shown in FIG. 4, the resistance value of the induction motor 1 exhibits a first-order characteristic with respect to ΔI ² t. However, it is generally known that when the current flowing through the induction motor 1 varies depending on the load state of the induction motor 1, the final temperature rise value differs.Since the temperature rise of the induction motor 1 and the resistance rise are in a proportional relationship, Figure 7 (a) characteristic of the resistance value of the current I of the induction motor 1 for parameter Isseki as sigma iota ² t as shown in can be obtained and the relationship of the resistance change coefficients are shown in Figure 7 (b) The characteristic is such that the current I is parametric.

Further, FIG. 8 shows the characteristic of FIG. 7 (b) as a relationship between the resistance value and the resistance change coefficient. Therefore, the resistance change coefficient of the primary resistance and the secondary resistance is calculated for each actual operation cycle according to the same operating principle as that of the control device for the induction motor shown in Fig. 3, and the current is set as a parameter and the resistance characteristic memory 1 la When the resistance change coefficients K Rl and K R2 are called out as a function of the resistance as a function of the resistance during the actual operation cycle, the actual resistance change for multiple load conditions of the induction motor can be obtained. The coefficient can be set according to

FIG. 9 is a block diagram showing another embodiment of the control device for the induction motor according to the second embodiment of the present invention, and the same reference numerals as in FIG. 3 denote the same or corresponding parts. In Fig. 9, 11a is a relation between the resistance change coefficient and the resistance value, with the current detected by the current detector 3 as a parameter after inputting the resistance measurement device 7 and the output of the resistance change coefficient calculator 8 Is stored in the resistance characteristic storage device.

The resistance characteristic memory 11a stores the change coefficients K Rl and K R2 of the primary resistance and the secondary resistance output from the resistance change coefficient calculator 8 and the current of the induction motor 1 detected by the current detector 3. An operation is performed to store the relationship between the resistance value and the resistance change coefficient as shown in Fig. 8 with the input current as a parameter.

Further, the resistance characteristic storage 11a stores the stored resistance value and the resistance change coefficient. That is, from the data of the resistance change coefficient characteristic stored corresponding to the current value closest to the current detected by the current detector 3, the closest value to the measured resistance value at startup measured by the resistance measuring device 7 The resistance change coefficient corresponding to the resistance value is output to the resistance change estimator 9a. The resistance fluctuation estimator 9a receives the resistance change coefficient output from the resistance characteristic storage 11a, and operates the primary resistance and the secondary resistance by the same operation as the induction motor control device described in FIG. The estimated value is calculated and output to the sensorless vector controller 6. By repeating this series of operations, resistance change coefficients K Rl and K R2 for a plurality of resistance values are stored in the resistance characteristic memory 11a, and a more detailed relationship between the resistance value and the resistance change coefficient is accumulated. Is performed. Further, it is used for the resistance estimation by the resistance fluctuation estimator 9a, so that highly accurate resistance estimation can be realized. Furthermore, since the relationship between the resistance change coefficient and the resistance value is stored and stored with the current as a parameter, it is possible to set a coefficient corresponding to the actual resistance change with respect to a plurality of load states of the induction motor 1. There is an effect that a highly accurate resistance value can be estimated regardless of the magnitude of the resistance. In the description of the control device for the induction motor shown in FIG. 9, the resistance change coefficient corresponding to the resistance value closest to the resistance measured value at startup measured by the resistance measurement device 7 is calculated by using the resistance variation estimator 9a. However, during operation, the estimated value of the resistance output from the resistance fluctuation estimator 9a is input to the resistance characteristic memory 11a, and the resistance value corresponding to the resistance value closest to the resistance value is sequentially stored. May be output to the resistance fluctuation estimator 9a. As a result, even when the resistance change coefficient changes due to continuous operation for a long time, the optimum value is used according to the change in the estimated resistance value, and a more accurate resistance value estimation is performed. There is an effect that can be done.

Embodiment 3.

In the second embodiment, the relationship between the resistance value and the resistance change coefficient is stored while performing the normal operation. Cycle operation at a time interval shorter than the thermal time constant of the induction motor 1 and store in advance the resistance change coefficients for the resistance values at multiple points in the temperature range of the induction motor 1 that can be taken in the normal operation state. Good.

FIG. 10 is a block diagram showing a control device for an induction motor according to Embodiment 3 of the present invention, and the same reference numerals as in FIG. 3 denote the same or corresponding parts. In FIG. 10, reference numeral 12 denotes an operation mode setting device for setting the operation mode of the induction motor 1, and reference numeral 5c denotes a speed command and an output from the operation mode setting device 12 which are outputs from the speed command generator 4. This is a tuning controller that controls tuning by inputting operation mode commands.

Next, the operation of the control device for an induction motor according to the third embodiment will be described. First, when the test operation mode is set in the operation mode setting device 12, the tuning controller 5 c switches so as to have a predetermined test cycle for the test. Next, when the speed command ω ιη * is input from the speed command generator 4, the tuning controller 5c closes the control switch 10 to the resistance measuring device 7 side, and further outputs a resistance measurement start signal to the resistance measuring device. Output to 7. When the resistance measurement device 7 receives the resistance measurement start signal from the tuning controller 5c, the resistance measurement device 7 starts measuring the primary and secondary resistance values of the induction motor 1. Note that the resistance measuring device 7 measures the resistance value in the same manner as the method described in the first embodiment.

Next, when the resistance measurement device 7 completes the measurement of the primary resistance and the secondary resistance, it outputs the completion of the resistance measurement to the tuning controller 5c, and at the same time, the resistance change coefficient calculator 8 and the resistance characteristic storage device 1 The measurement result is output to 1 and the resistance fluctuation estimator 9a. When the resistance measurement completion signal output from the resistance measurement device 7 is input, the tuning controller 5c operates so as to close the control switch 10 to the sensorless vector controller 6 side, and the sensorless vector control is performed. The operation of the induction motor 1 is started by the switching signal output from the heater 6.

Then, after a lapse of time shorter than the thermal time constant of the induction motor, the induction motor 1 is turned off. Decelerate and stop, and output a stop completion signal from the sensorless vector controller 6 to the tuning controller 5c. The tuning controller 5c outputs a resistance measurement start signal to the resistance measurement device 7 in response to the input of the stop completion signal, and the resistance measurement device 7 receives the resistance measurement start signal again and operates in the same manner as when starting. Starts the measurement of the primary resistance and secondary resistance of induction motor 1 when stopped.

Further, when the resistance measurement device 7 completes the measurement of the primary resistance and the secondary resistance, a resistance measurement completion signal is sent to the tuning controller 5c, and the measurement result is output to the resistance change coefficient calculator 8 at the same time. Is done. The resistance change coefficient calculator 8 includes a control signal output from the tuning controller 5c, a current I of the induction motor 1 output from the current detector 3, and an induction signal input from the resistance measuring device 7. Input the measured values of the primary resistance and secondary resistance at the start and immediately after the stop of motor 1, and use the same method as described in Embodiment 1 for the primary resistance per unit quantity (I ² t = 1). Calculate the change coefficients K Hl and K R2 of the secondary resistance and output them to the resistance characteristic storage 11. Further, the tuning controller 5c outputs a control signal so that the above cycle is repeated until the number of operations, the operation time, or the amount of change in the resistance measurement value reaches a preset value, and as a result, The resistance characteristic storage unit 11 stores resistance change coefficients K R1 and K R2 for a plurality of resistance values.

Next, when a predetermined test cycle for testing ends, the tuning controller 5c switches from the test operation mode to the normal operation mode. From the next start-up, the same operation as described in the second embodiment is performed, and the resistance characteristic storage 11 stores the resistance value and the resistance change coefficient stored at the start-up, which are measured by the resistance measurement device 7. The resistance change coefficient corresponding to the resistance value closest to the value is output to the resistance change estimator 9a. The resistance change estimator 9a receives the resistance change coefficient output from the resistance characteristic storage 11 and calculates the estimated values of the primary resistance and the secondary resistance by the same operation described in the first embodiment. Output to the sensorless vector controller 6. As a result, in the actual operation cycle in the normal operation state, there is an effect that the more appropriate relationship between the resistance value and the resistance change coefficient is stored, and the resistance fluctuation can be well estimated. Further, it is possible to omit the resistance measurement at the time of starting and immediately after stopping, which has an effect that the starting can be accelerated.

Note that the resistance characteristic storage 11 performs a function of smoothly interpolating a resistance change coefficient for a plurality of resistance values stored in a predetermined test operation mode by performing a polynomial approximation or a function approximation using a least squares method. May be stored.

As a result, when referring to the resistance change coefficient from the resistance value, the resistance change coefficient can be referred to as a value closer to the actual change, and there is an effect that the resistance change can be well estimated.

Also, in the normal actual operation cycle, the resistance estimation value immediately after the stop estimated by the resistance fluctuation estimator 9a is compared with the resistance measurement value immediately after the stop measured by the resistance measuring instrument 7, and the difference between these values is determined. When the resistance value exceeds the resistance value, the resistance characteristic storage unit 11 is configured to correct the relationship between the resistance value and the resistance change coefficient stored in the storage unit.This allows the induction motor temperature to change due to a change in temperature or environmental change around the motor. The characteristics stored in the resistance characteristic storage unit 11 can always be corrected to match the actual characteristics even if the temperature difference between However, there is an effect that the resistance fluctuation can be estimated well. Further, during the operation of the normal actual operation cycle, the resistance change estimator 9a is referred to the resistance change coefficient stored in the sequential resistance characteristic storage 11 using the resistance value estimated by the resistance change estimator 9a. In a, the resistance value may be estimated using the referred resistance change coefficient.

This makes it possible to set a resistance change coefficient that sequentially corresponds to the resistance value that changes due to the temperature rise of the induction motor during operation, and it is possible to estimate the resistance change well even if the resistance change amount from the start is large. There is. Embodiment 4.

In the above-described embodiment, the resistance value change due to the temperature change of the induction motor 1 is estimated, and the member 2 is controlled using the resistance value estimated by the sensorless vector controller 6. The configuration may be such that the temperature rise of the induction motor 1 is further estimated from the resistance value change.

FIG. 11 is a block diagram showing a control device for an induction motor according to Embodiment 4 of the present invention, and the same reference numerals as in FIG. 3 denote the same or corresponding parts. In Fig. 11, 13 is a temperature estimator that estimates the temperature of the induction motor 1 by inputting the resistance estimation value output from the resistance fluctuation estimator 9a, and 5d is the output from the speed command generator 4. This is a tuning controller that controls a tuning by inputting a certain speed command and an estimated temperature of the induction motor 1 which is an output from the temperature estimator 13.

The temperature estimator 13 stores in advance the resistance values of the primary and secondary resistors in a state where the temperature of the induction motor 1 measured by the resistance measuring device 7 is substantially known. Next, the resistance estimation value output from the resistance fluctuation estimator 9a is input, and the ratio between the resistance value stored in advance and the thermal resistance specific to the material of the primary conductor and the secondary conductor of the induction motor 1 are calculated. The temperature of the primary conductor and the secondary conductor of the induction motor 1 is estimated from the change coefficient. For example, if the material of the primary conductor is copper, and the resistance value measured by the resistance measuring device 7 at the temperature t 0 ° C is Rl (tO), the resistance value output from the resistance fluctuation estimator 9a is Rl (tO). The temperature t 1 ° C of the induction motor 1 at (tl) can be estimated by equation (14). tl = (2345 + 1 ^{1 1} )-234.5 _r C;] (1 4), no i? l (0) Further, the tuning controller 5 d outputs the induction motor 1 output from the temperature estimator 13. Enter the above temperature estimate, and set the temperature above the preset temperature. Ichino

When the estimated value increases, the operation is performed to stop the induction motor 1 to prevent burnout.

Here, when measuring the resistance value of the induction motor 1 at a roughly known temperature, n'-1 is in the same temperature state as the ambient temperature even if the conductive motor 1 does not have a special detector such as a thermocouple. Sometimes, the resistance value is measured by the resistance measuring device 7, and the measured ambient temperature at that time may be set as the temperature of the induction motor 1.

The tuning controller 5 d inputs the above-mentioned temperature estimation value of the induction motor 1 output from the temperature estimator 13, and if the temperature estimation value rises above a preset temperature, the induction controller 1 d Instead of stopping, an alarm signal may be output to the outside. Further, as the temperature display of the induction motor 1, the temperature estimation value estimated by the temperature estimator 13 may be displayed.

As described above, according to the present invention, a resistance change coefficient for calculating a resistance change coefficient based on the resistance value measured by the resistance measuring device 7 immediately after the start and immediately after the stop and the current detected by the current detector 3 A resistance calculator that inputs the resistance value measured by the resistance calculator 8 and the resistance change coefficient calculated by the resistance change coefficient calculator 8 and stores the relationship between the resistance change coefficient and the resistance value. The resistance variation is calculated based on the characteristic storage 11, the current detected by the current detector 3, the resistance value at startup measured by the resistance measuring means, and the resistance change coefficient output from the resistance characteristic storage 11. A resistance fluctuation estimator 9a for estimating and a temperature estimator 13 for estimating the temperature of the induction motor 1 from the estimated resistance value output from the resistance fluctuation estimator 9a are provided. Set thermal resistance, thermal time constant, etc. Ku, there is an effect that it estimates the temperature rise of the induction motor. The primary resistance value of the induction motor 1 measured by the resistance measuring device 7 is measured including the wiring resistance from the inverter 2 to the induction motor 1. However, the wiring from Inver 2 to induction motor 1 is usually too hot. Since the wiring is selected and laid so that it does not rise, the temperature change is set in the temperature estimator 13 in advance to the wiring resistance Rh, and assuming that the wiring resistance Rh is constant during operation, the equation (14) is used. Equation (15) may be used instead. l-2345) 1 5

J

Here, the resistance value of the wiring from the inverter 2 to the induction motor 1 can be set to a value measured with a low-resistance measuring device such as a pager or a millimeter, or the resistance per unit length of the wiring. If the value is known in advance by the manufacturer's data or the like, the value may be obtained by calculation by multiplying it by the wiring length and set.

As a result, even if the wiring resistance from the inverter 2 to the induction motor 1 is relatively large, it is possible to more accurately estimate the primary resistance fluctuation of the induction motor 1 and thereby reduce the temperature rise of the induction motor 1. This has the effect of being able to estimate well.

In all of the above-described embodiments, there are many known resistance measuring methods for measuring the resistance of the induction motor 1 using the inverter 2 such as single-phase application, low-voltage three-phase application, and the like. Further, it goes without saying that the control device for the induction motor of the present invention can be configured using any other resistance measuring method.

Needless to say, these embodiments can be implemented in an appropriate combination. Industrial applicability

As described above, according to the present invention, the control device for the induction motor and the control method for the induction motor include, for example, a resistor for temperature change during operation of the winding of the induction motor. A control device for an induction motor that performs vector control and sensorless vector control so that the induction motor follows the command speed based on the estimated winding resistance value based on the estimated winding resistance value, and an induction motor control device. Suitable for control method.

Claims

The scope of the claims

1. Inverter for controlling the induction motor; resistance measuring means for measuring a winding resistance of the induction motor; and a difference between the winding resistance measured before and after a first operation cycle and the first. Resistance change coefficient calculation means for calculating a resistance change coefficient of the winding resistance per unit amount of the value based on a value related to the amount of heat generated by the induction motor generated during the operation cycle of the above, and the resistance measurement means Is the starting winding resistance measured at the start of the second operation cycle following the first operation cycle, the value related to the calorific value of the induction motor during the second operation cycle, and the resistance change coefficient. A control device for an induction motor, comprising: a resistance fluctuation estimating means for outputting an estimated winding resistance value estimated on the basis of the above, and a control means for controlling the chamber using the estimated winding resistance value.

2. The resistance change coefficient calculating means calculates a value related to a heat value of the induction motor generated during the first operation cycle based on a current value supplied to the induction motor, and the resistance fluctuation estimating means calculates 2. The control device for an induction motor according to claim 1, wherein a value related to a calorific value of the induction motor generated during the operation cycle is calculated based on a current value supplied to the induction motor.

3. The resistance change coefficient calculation means calculates a value related to the heat generation amount of the induction motor generated during the first operation cycle based on a torque command value instructed to the induction motor, and the resistance variation estimation means includes: The control of the induction motor according to claim 1, wherein a value related to a calorific value of the induction motor generated during the second operation cycle is calculated based on a torque command value instructed to the induction motor. apparatus.

4. The resistance fluctuation estimating means calculates the stop-time winding resistance measured by the resistance measuring means at the time of stopping the first operation cycle as the starting-time winding resistance measured at the time of starting the second operation cycle. 2. The control device for an induction motor according to claim 1, wherein an estimated winding resistance value during an operation cycle is output.

5. Inverter for controlling the induction motor; resistance measuring means for measuring a winding resistance of the induction motor; and a difference between the winding resistance measured before and after a first operation cycle and the first. A resistance change coefficient calculating means for calculating a resistance change coefficient of the winding resistance per unit amount of the value based on a value related to a heat generation amount of the induction motor generated during the operation cycle of the above; And the relationship between the winding resistance value and the resistance measurement means, and the resistance measurement means stores the relationship based on the starting winding resistance value measured at the start of the second operation cycle following the first operation cycle. Resistance characteristic storage means for outputting a resistance change coefficient with reference to the resistance change coefficient output from the resistance characteristic storage means based on the starting winding resistance value and the resistance change coefficient of the induction motor in the second operation cycle. Estimated from the value related to the calorific value A resistance variation estimating means for outputting the resistance value estimated, the control equipment of the induction motor and a control means for controlling the Inba Isseki using the estimated winding resistance value.

6. The resistance characteristic storage means stores the current value during the first operation cycle as a parameter and stores the relationship between the resistance change coefficient and the winding resistance value, and the resistance measurement means activates the second operation cycle. 6. The induction motor according to claim 5, wherein a resistance change coefficient corresponding to the winding resistance measured at the time of startup is output with reference to the current value of the second operation cycle. Control device.

7. The resistance characteristic storage means stores a function approximation of the relationship between the resistance change coefficient calculated by the resistance change coefficient calculation means in the first operation cycle and the winding resistance value measured by the resistance measurement means at that time. The control device for an induction motor according to claim 5, wherein:

8. The resistance change coefficient calculation means compares the estimated winding resistance estimated when the second operation cycle is stopped with the stop winding resistance measured by the resistance measurement means when the second operation cycle is stopped. The difference between the winding resistance value and the resistance change coefficient stored in the resistance characteristic storage means when the difference of the resistance exceeds a predetermined value. 6. The control device for an induction motor according to claim 5, wherein:

9. The relationship between the temperature of the winding of the induction motor and the resistance of the winding is stored in advance, and the temperature of the winding and the resistance of the winding are based on the estimated winding resistance output by the resistance change coefficient calculating means. 6. The control device for an induction motor according to claim 5, further comprising temperature estimating means for estimating the temperature of the winding from the relationship with

10. The temperature estimating means previously stores the resistance value of the wiring from the inverter to the induction motor, and based on the value obtained by subtracting the resistance value of the wiring from the primary winding resistance value output by the resistance measuring means. 10. The control device for an induction motor according to claim 9, wherein the temperature of the primary winding is estimated.

11. The temperature estimating means outputs a stop signal for stopping the operation of the induction motor to the control means when the temperature of the winding exceeds a predetermined value, so that the control means stops the operation in the evening. 10. The control device for an induction motor according to claim 9, wherein:

1 2. Prior to the first and second operation cycles, measured by the resistance measurement means at the start and stop of each operation cycle of the predetermined operation cycle that repeats the set number of times by the resistance change coefficient calculation means. The resistance change coefficient of the winding resistance per unit quantity is calculated for each of the operation cycles from the difference between the obtained winding resistance values and the value related to the calorific value of the induction motor generated during each of the operation cycles. 6. The guidance according to claim 5, further comprising an operation mode setting unit configured to store a relationship between the resistance change coefficient and the winding resistance value for each of the operation cycles in a characteristic storage unit. Motor control device.

13 3. Based on the difference between the winding resistance measured before and after the operation cycle and the value related to the calorific value of the induction motor generated during the operation cycle, the winding resistance per unit amount of this value is calculated. A coefficient calculation step for calculating a resistance change coefficient; a startup resistance measurement step for measuring a startup winding resistance value at the start of the next driving cycle; and the resistance change coefficient based on the startup winding resistance. During the driving cycle A winding resistance estimating step of outputting an estimated winding resistance value estimated from a value related to a heat generation amount of the induction motor, and controlling an inverter for driving the induction motor based on the estimated winding resistance value. A control method for an induction motor, comprising: a control step for performing a stop; and a resistance measurement step for stopping when the operation cycle is stopped.

14. Based on the difference between the winding resistance measured before and after the operation cycle and the value related to the heat generated by the induction motor during the operation cycle, the winding resistance per unit amount of this value is calculated. A coefficient calculation step for calculating a resistance change coefficient; a storage step for storing a relationship between the winding resistance and the resistance change coefficient; and a start-up resistance measurement for measuring a start-up winding resistance value at the start of the next operation cycle. A step for determining a resistance change coefficient corresponding to the winding resistance at the start-up with reference to the relationship between the winding resistance and the resistance change coefficient; and A winding resistance value estimating step of outputting an estimated winding resistance value estimated from a resistance change coefficient corresponding to the winding resistance and a value related to a calorific value of the induction motor during the operation cycle; and the estimated winding resistance value. Based on the induction Inba a control step for controlling the Isseki, control method for an induction motor and a stop-time resistance measurement step of measuring a stop time 卷線 resistance when stopping of the said operation cycle to drive the machine.