JP3320073B2 - Induction motor control device and induction motor control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an induction motor for controlling an induction motor based on a specified winding resistance value by estimating a change in a winding resistance value due to a temperature change during operation of the induction motor. The present invention relates to a control device and a control method for an induction motor.

BACKGROUND ART As a method for controlling an induction motor with high performance, a vector control method and a sensorless vector control for controlling by performing an estimation calculation of a speed are performed. These controls are based on the primary winding and secondary winding, which are equivalent circuit constants of the induction motor.
Next, it is necessary to accurately set secondary resistance, mutual inductance, primary and secondary leakage inductance, and the like as control constants, which are measured and set before operation.

However, since the primary and secondary resistances change according to 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 is deteriorated, and the speed control accuracy is deteriorated in the sensorless vector control.

Further, in the sensorless vector control, when the primary resistance set value has an error with respect to its actual value, not only the control accuracy is deteriorated, but also the control itself becomes unstable, which may cause an overcurrent trip or the like.

In order to solve this problem, Japanese Patent Application Laid-Open No. 7-213100 discloses that in a sensorless inverter device, a secondary resistance of an induction motor at a cold time is measured and set as an initial value in the inverter. A sensorless inverter device with resistance fluctuation compensation for estimating secondary resistance fluctuation due to temperature rise from time and correcting the secondary resistance used for speed calculation is disclosed.

FIG. 12 is a block diagram of a sensorless inverter device with resistance fluctuation compensation described in Japanese Patent Application Laid-Open No. 7-213100, which has been rewritten for easy comparison with the control device of the present invention.

In the drawing, 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, 9b is a resistance fluctuation estimator, 10 is a switch, 20 is a voltage detector, 21 Is an initial value measuring device, and 22 is an initial measurement setting device.

The inverter 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.

The switch 10 closes to the initial value measuring device 21 only at the start of operation immediately after the control power supply is turned on, and outputs a switching signal output from the initial value measuring device 21 to the inverter 2.
In response to the switching signal of the initial value measuring device 21, a DC voltage is applied from the inverter 2 to the induction motor 1 on average. After a certain period of time, the current Ix of the induction motor 1 is measured by the current detector 3, and the initial value θ0 of the temperature rise of the induction motor 1 is obtained from the equation (1) and output to the resistance fluctuation estimator 9b. Here, Ix0 is a current measurement value of the secondary resistor R2n by the same method when the temperature of the induction motor 1 is equal to the ambient temperature, and K1 is a conversion coefficient between temperature and current.

θ ₀ = (I _X0 −I _X ) / I _X0 / K1 (1) The resistance fluctuation estimator 9b outputs the current I which is the output of the current detector 3.
, The temperature rise θ of the induction motor 1 is estimated by the equation (2), and the secondary resistance fluctuation is estimated and corrected by the equation (3) using R2n input from the initial measurement setting unit 22. The next resistance R2x is output to the sensorless vector controller 6. Here, K is a conversion gain, and T is a time constant.

θ = KI ² {1 / (1 + ST)} (2) R2 _X = (1 + K1θ) R2 _n (3) The sensorless vector controller 6 outputs a speed command value which is an output of the speed command generator 4. ωm ^* , the current I which is the output of the current detector 3, the voltage V which is the output of the voltage detector 20, and the modified secondary resistance R2x which is the output of the resistance fluctuation estimator 9b are input and set internally. The speed of the induction motor 1 is controlled so as to follow the command value ωm ^* using the set value and the control gain other than the secondary resistance of the induction motor 1.

Since the conventional induction motor control device is configured as described above, it is necessary to set the thermal resistance, thermal time constant, and the like of the induction motor in advance. In particular, since these heat-related constants vary depending on the motor to be driven, and also vary depending on installation conditions, etc., it is necessary to measure and set in advance in actual use conditions, and inverters are generally used for different types of motors. In addition, in order to protect the induction motor from overheating, it is necessary to mount a thermocouple or the like inside the motor to measure the temperature of the induction motor. There was a point.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and estimates a resistance change while calculating a resistance change characteristic of an induction motor in an actual use state, and estimates a speed based on the result, and calculates a slip based on the result. An object of the present invention is to provide an induction motor control device and an induction motor control method capable of satisfactorily controlling the induction motor without previously setting the thermal resistance, 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 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. And a value relating to the amount of heat generated by the induction motor generated during the first operation cycle, a resistance change coefficient of the winding resistance per unit amount of this value is calculated. Estimation estimated based on the starting winding resistance measured at the start of the second operation cycle following the first operation cycle, the value added to the calorific value of the induction motor during the second operation cycle, and the resistance change coefficient. Since the winding resistance is output and the control means controls the inverter that drives the induction motor using the estimated winding resistance, even if the heating value of the induction motor changes, the installation conditions may differ or the thermal time constant may change. For different induction motors This also makes it possible to estimate the resistance variation that changes according to the operation cycle, and to accurately control the speed of the induction motor using the estimated resistance value.

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 amount of heat generated by the induction motor during the second operation cycle based on the current value supplied to the induction motor, the heat generation of the induction motor due to a change in the current value during the operation cycle is performed. Even if the amount changes, the resistance fluctuation can be estimated, and the speed of the induction motor can be accurately controlled using the estimated resistance value.

In the control device for an induction motor according to 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 torque command value instructed to the induction motor. Since the resistance variation estimating means calculates a value related to the amount of heat generated by the induction motor during the second operation cycle on the basis of the torque command value instructed to the induction motor, the induction motor based on a change in the command torque in the operation cycle. Can be estimated even if the heat value of the motor changes, and the speed of the induction motor can be accurately controlled using the estimated resistance value.

In the control device for an induction motor according to the present invention, the resistance fluctuation estimating means may be configured to start up by measuring the stop 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 during the second operation cycle is output as the time winding resistance, the resistance measuring means does not have to measure the winding resistance at startup in the second operation cycle, and the time required for startup is reduced. Becomes shorter.

Further, in the control device for an induction motor 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. And a value relating to the amount of heat generated by the induction motor generated during the first operation cycle, a resistance change coefficient of the winding resistance per unit amount is calculated from the value, and the resistance characteristic storage means stores the resistance change coefficient and the resistance change coefficient. The relationship with the winding resistance value is stored, and the resistance measuring means refers to the relationship stored based on the starting winding resistance value measured at the start of the second operation cycle following the first operation cycle. A change coefficient is output, and the resistance change estimating means estimates the winding based on the resistance change coefficient output from the resistance characteristic storing means based on the winding resistance value at the time of starting and the value related to the heat value of the induction motor during the second operation cycle. The wire resistance is estimated and output, and the control means Since the inverter that drives the induction motor is controlled using the winding resistance value, the resistance fluctuation estimating means uses the resistance change coefficient output from the resistance characteristic storage means and the starting winding resistance measured at the start of the operation cycle. It is also possible to estimate the resistance fluctuation, without having to set the thermal resistance, thermal time constant, etc. in advance, and even when the resistance at the time of startup greatly differs from the resistance at the time of startup of the previous operation cycle. 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 relationship between the resistance change coefficient and the winding resistance value using the current value during the first operation cycle as a parameter, and the resistance measurement means stores The resistance characteristic storage means outputs the resistance change coefficient corresponding to the starting winding resistance value measured at the start of the second operation cycle with reference to the current value of the second operation cycle. Value and coefficient of resistance change
From the data of the resistance change coefficient characteristic stored corresponding to the current value closest to the current value of the operation cycle, a resistance change coefficient is output based on the starting winding resistance measured at the start of the operation cycle. As a result, it is possible to set a resistance change coefficient suitable for a resistance change due to a plurality of load states of the induction motor, and it is possible to estimate a winding resistance value with high accuracy regardless of the size of the load.

Further, in the control device for the induction motor 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 value measured by the resistance measurement means at that time. Is stored as a function approximation, so that the 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.

In the control device for an induction motor according to 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 measurement means at the time of stoppage measured at the time of stopping the second operation cycle. Since the winding resistance is compared with the winding resistance and if the difference exceeds a predetermined value, the relationship between the winding resistance and the resistance change coefficient stored in the resistance characteristic storage means is corrected.
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 due to a change in air temperature or a change in the environment around the induction motor occurs, the winding resistance value stored in the resistance characteristic storage means. And the resistance change coefficient can be corrected so as to match the actual state, and the resistance fluctuation can be satisfactorily estimated.

In the control device for an induction motor according to the present invention, the temperature estimating means pre-stores a relationship between the temperature of the winding of the induction motor and the winding resistance, and the estimated winding resistance outputted by the resistance change coefficient calculating means. Since the temperature of the winding is estimated from the relationship between the temperature of the winding and the resistance of the winding based on the above, it is possible to estimate the temperature of the induction motor without previously setting the thermal resistance and the thermal time constant of the induction motor. it can.

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 calculates the resistance value of the wiring from the primary winding resistance value output by the resistance measuring means. Since the temperature of the primary winding is estimated based on the subtracted value, even when the wiring length from the inverter to the induction motor is relatively long, the primary winding resistance is separated from the wiring resistance to separate the induction motor. The temperature of the primary winding can be estimated.

In the control device for an induction motor of the present invention, the temperature estimating means outputs a stop signal to stop the operation of the induction motor to the control means when the temperature of the winding exceeds a predetermined value, and the control means , The overheating of the induction motor can be prevented without mounting a thermocouple or the like inside the motor.

Further, in the control device for the induction motor of the present invention, the operation mode setting means may perform each of the predetermined operation cycles in which the resistance change coefficient calculation means repeats the set number of times before the first and second operation cycles. 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 amount of heat generated by the induction motor during each operation cycle, the resistance change coefficient of the winding resistance per unit quantity Is subtracted for each operation cycle, and the resistance characteristic storage means stores the relationship between the resistance change coefficient and the winding resistance value for each operation cycle. The relationship is stored in the resistance characteristic storage means in advance, and in the second operation cycle, a more appropriate relationship between the winding resistance value and the resistance change coefficient is stored, so that the resistance fluctuation can be satisfactorily estimated. .

In addition, the control method of the induction motor of the present invention uses a unit of this value based on a difference between a winding resistance value measured before and after an operation cycle and a value related to a calorific value of the induction motor generated during the operation cycle. Calculate the resistance change coefficient of the winding resistance per unit, measure the winding resistance at startup at the start of the next operation cycle, and calculate the resistance change coefficient based on the winding resistance at startup and the induction motor during the operation cycle. Output the estimated winding resistance value estimated from the value related to the calorific value of the motor, controls the inverter that drives the induction motor based on the estimated winding resistance value, and determines the stop-time winding resistance value when the operation cycle is stopped. Because of the measurement, even if the heat value of the induction motor changes, it is possible to estimate the resistance fluctuation that changes with the operation cycle even for installation motors with different installation conditions and different thermal time constants. Accuracy using You can control the speed of the Ku induction motor.

In addition, the control method of the induction motor of the present invention uses a unit of this value based on a difference between a winding resistance value measured before and after an operation cycle and a value related to a calorific value of the induction motor generated during the operation cycle. Calculates the resistance change coefficient of the winding resistance per unit, stores the relationship between the winding resistance and the resistance change coefficient, measures the starting winding resistance at the start of the next operation cycle, and calculates the starting winding resistance. The corresponding resistance change coefficient is determined with reference to the relationship between the winding resistance and the resistance change coefficient, and based on the start winding resistance, the resistance change coefficient corresponding to the start winding resistance and the induction motor during the operation cycle are determined. Outputs the estimated winding resistance value estimated from the value related to the calorific value, controls the inverter that drives the induction motor based on the estimated winding resistance value, and measures the winding resistance value when the operation cycle is stopped when the operation cycle is stopped Measurement at the start of the operation cycle. Based on the starting winding resistance obtained, a resistance change coefficient corresponding to the starting winding resistance of the operation cycle is obtained by referring to a relationship between the winding resistance and the resistance change coefficient, and the heat resistance during the operation cycle is determined. It is possible to estimate the resistance variation using the value, without previously setting the thermal resistance, thermal time constant, etc., and furthermore, the resistance at the time of startup greatly differs from the resistance at the time of startup of the previous operation cycle. The winding resistance can be well estimated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 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. 2 is a flowchart showing a control method of the control device for the induction motor shown in FIG. 1, FIG. 3 is a block diagram of the control device for the induction motor 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. 7 is a flowchart showing a control method of the control device of the induction motor shown in FIG. 3; FIG. 7 is an explanatory diagram showing a winding resistance value and a resistance change coefficient using a current value of a general induction motor as a parameter;
FIG. 9 is an explanatory diagram of a relationship between a winding resistance value and a resistance change coefficient stored in the resistance characteristic storage unit 11a shown in FIG. 9, and FIG. 9 is a control device for an induction motor according to another embodiment of the second embodiment of the present invention. FIG. 10 is a block diagram showing a control device for an induction motor according to Embodiment 3 of the present invention, FIG. 11 is a block diagram showing a control device for an induction motor according to Embodiment 4 of the present invention, and FIG. FIG. 1 is a block diagram showing a conventional control device for an induction motor.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. FIG. 1 is a block diagram showing an 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 a 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, and 6 is a sensorless vector control for controlling the induction motor 1. , A starter 1 and a secondary winding 1 of the induction motor 1 at the time of start and stop.
This is a resistance measuring instrument for measuring the secondary and secondary resistance. here,
The secondary winding includes a cage winding. 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; 9a is a resistance change coefficient calculation of the current detector 3, the resistance measurement device 7 A resistance variation estimator for designating the resistance variation of the induction motor 1 based on the output of the device 8; a control switch 10 that closes the resistance measuring device 7 when starting and stopping, and closes the sensorless vector controller 6 when operating. And is controlled by the tuning controller 5a.

Next, the operation will be described with reference to the drawings. First, at the start-up when the speed command ωm ^* is input from the speed command generator 4, the tuning controller 5 a operates so as to close the control switch 10 to the resistance measuring device 7 side, and is output from the resistance measuring device 7. The switching signal allows the inverter 2 to output a voltage to the induction motor 1. Furthermore, the resistance measurement start signal from the tuning controller 5a is
And the resistance measuring device 7 is connected to the primary and secondary of the induction motor 1.
Start measurement of the next resistance value.

Here, the resistance measurement performed by the resistance measuring device 7 may use a method described in, for example, JP-A-62-79380. That is, a DC current _ID is generated in the output of the inverter 2 in a stepwise manner, and the final value V1 (∞) of the primary voltage V1 of the induction motor 1 and the ratio of the DC current V1 (∞) / I
_{Find the} primary resistance R1 from _D and calculate the primary voltage V1 by the DC current _ID.
Of the transient voltages V1 (t1), V1 (t2) and the final value V1 at times t1 and t2
From (∞) to (4), the secondary time constant τ2 of the induction motor 1 is obtained, and using this time constant τ2, the secondary resistance R2 is obtained from (5). Note that τ2 = L2 / R2, and L2
Is a constant value even if the temperature changes, so that it can be set accurately in advance.

Here, in order to generate the DC current _ID in the output of the inverter 2 in a step-like manner, a current controller generally used in normal vector control or the like is provided inside the resistance measuring device 7 and the step-like current controller is provided. What is necessary is just to give a current command to the inverter 2.

When the final value V1 (∞) of the primary voltage V1 is obtained, since the secondary time constant is several tens msec to several hundred msec in the ordinary induction motor 1, the time is several hundreds of several hundred msec.
The value at the time of msec to several seconds is the final value V1 (∞) of the primary voltage V1.
In this case, 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 fluctuation estimator 9a. The measurement result is output. When the tuning controller 5a receives the resistance measurement completion signal output from the resistance measuring device 7, the tuning controller 5a operates to close the control switch 10 to the sensorless vector controller 6, and the tuning controller 5a outputs the signal from the sensorless vector controller 6. The operation of the induction motor 1 is started by the switching signal.

Thereafter, 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 is decelerated and stopped, a stop completion signal is sent from the sensorless vector controller 6 to the tuning control. Output to the container 5a. The tuning controller 5a outputs a resistance measurement start signal to the resistance measuring device 7 in response to the input of the stop completion signal, and when the resistance measurement starting signal is input, the resistance measuring device 7 guides again in the same manner as when starting. Electric motor 1
The measurement of the primary resistance and the secondary resistance value is started.

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 5a, and the measurement result is output to the resistance change coefficient calculator 8 at the same time. The resistance change coefficient calculator 8 includes a control signal output from the tuning controller 5a and the current detector 3
Current I of the induction motor 1 output from the
At the start and immediately after the start of the induction motor 1
The measured values of the primary and secondary resistances are input, and the difference between the measured primary and secondary resistances at startup and immediately after the stop is integrated during the operation time of the induction motor, ΔI ² t (time of current square value) divided by the integral value), (6) and (7) a unit amount obtained (I ² t = 1) 1 primary resistance and the variation coefficient of the secondary resistance KR1, KR2 operation to resistance variation estimated per Output to the container 9a. This is because the temperature rise of the winding of the induction motor 1 is substantially proportional to the resistance loss 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. .

From the next start-up, 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 induction input from the resistance measuring device 7 are output by the resistance fluctuation estimator 9a. The measured values of the primary resistance and the secondary resistance of the motor 1 at the time of startup and the change coefficient KR1 of the primary resistance and the secondary resistance per unit quantity (I ² t = 1) output from the resistance change coefficient calculator 8 , KR2, and the primary resistance and secondary resistance estimated values R1 ^* , R2 ^* are calculated by the equations (8) and (9) using the measured values at the time of starting the primary resistance and the secondary resistance as initial values. And outputs it to the sensorless vector controller 6.

^{R1 * = KR1ΣI 2 t + R1} ( ^{startup) ··· (8) R2 * =} KR2ΣI 2 t + R2 ( at startup) (9) The sensor-less vector controller 6, the speed command that has passed through the tuning controller 5a The speed command value ωm ^* output from the generator 4, the current I output from the current detector 3, and the primary resistance and secondary resistance estimated values R1 ^* and R2 ^* output from the resistance fluctuation estimator 9a are input. In addition, using the constant and control gain of the induction motor 1 set inside, the induction motor 1
Is controlled so that the speed of the control signal follows the command 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, step S11
, The change coefficients KR1 and KR2 of the primary resistance and the secondary resistance
Is set to an appropriate value. KR1 and KR2 may be zero if an error in the 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 DC 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 proceeds 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 values measured in step S13 are used as initial values, and KR1 and KR2 obtained last time are determined.
Estimating a KR1shigumaI ² t, variation in the primary resistance and secondary resistance during actual operation cycle operation as KR2shigumaI ² t than the current I flowing in the induction motor (the only step the initial value set in step S11 the first time), The sensorless vector controller 2 performs control using the estimated primary resistance and secondary resistance. In step S15, the tuning controller 5a determines whether a stop signal is given and the induction motor 1 is stopped, and returns to step S14 while the induction motor 1 is operating. When the stop signal is given and the induction motor 1 stops, in step S16, a DC current is supplied to the induction motor 1 again 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 the secondary resistance at the time of start-up measured in step S13 and the primary resistance and the secondary resistance at the time of stoppage measured in step S16 is calculated based on the actual operation cycle of the induction motor 1. ΣI ² t integrated over time
(Time integral of the current squared value) and divide by the unit quantity (i ² t =
1) Primary and secondary resistance change coefficients KR1 and K
Find R2. This completes a series of operations, and steps again
The process returns to S12 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 that change every moment during the actual operation cycle, and the sensorless vector controller 6
Controls precisely so that the speed of the induction motor 1 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. For estimating the resistance variation based on the detector 8, the current detected by the current detector 3, the resistance value at startup measured by the resistance measuring device 7, and the resistance change coefficient calculated by the resistance change coefficient calculator 8. Since the resistance fluctuation estimator 9a is provided, the resistance fluctuation of the induction motor 1 can be estimated without previously setting the thermal resistance, the thermal time constant, and the like.

Further, the resistance change coefficient calculator 8 calculates the difference between the resistance value at the start-up and the resistance value immediately after the stoppage measured by the resistance measuring device 7 during the operation time of the induction motor 1, and calculates the difference by the current detector 3. The resistance change coefficient is calculated by dividing the detected current by the time integral value of the square of the current and calculating the resistance change coefficient as the resistance change amount per unit calorie. Since the resistance value is estimated and calculated by multiplying the value obtained by multiplying the time integral value of the square value of the current detected by the current detector 3 by the resistance change coefficient as a resistance change value, the induction motor is used as an initial value. Even if the value of the current flowing through the switch 1 changes, the resistance fluctuation corresponding to the change can be estimated.

If the stop time is sufficiently small with respect to 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. That is, a stop time measuring device for counting 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 by the resistance measuring device 7 is reduced. The resistance measurement may be omitted, and the resistance measured immediately after the stop may be used as the resistance at the next startup.

Further, 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 appropriate intervals sufficiently shorter than the thermal time constant of the induction motor 1 to start. When a signal is input, the resistance value measured immediately before stopping may be used instead of the resistance measurement performed at startup by the resistance measuring device 7.

Thereby, the resistance measurement at the time of starting can be omitted, and there is an effect that the starting can be performed quickly.

Further, in the first embodiment, the resistance change coefficient calculator 8 and the resistance change estimator 9a use the current detector 3 to calculate the change coefficient of the primary resistance and the secondary resistance and the calculation of the estimation of the primary resistance and the secondary resistance. Is used, the current command value and the torque command value are created in the sensorless vector controller 6 using the square values as unit amounts. Is also good. If 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, the square value of the output is used as a unit amount. May be.

In the first embodiment, the resistance change coefficient calculator 8
Is the ΔI ² t (current 2) obtained by integrating the difference between the primary resistance and secondary resistance measured values at the start and immediately after the stop during the operation time of the induction motor.
Divided by the time integral value) of squared values, calculates the equation (6) and (7) a unit amount obtained by the formula (I ² t = 1) the variation coefficient of the primary resistance and secondary resistance per KR1, KR2 It was configured as follows. 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 equipped, the standard induction motor 1 does not cause a temperature rise under substantially no load. Confirmed by Therefore, the change coefficients KR1 and KR2 of the primary resistance and the secondary resistance are obtained by the resistance fluctuation estimator 9a.
May be calculated by the equations (10) and (11), assuming that the temperature rise of the induction motor 1 is proportional to the square of the current I minus the square of the no-load current I0.

When KR1 and KR2 are calculated by the equations (10) and (11), the resistance fluctuation estimator 9a sets the primary resistance and the secondary resistance at the time of startup measured by the resistance measuring instrument 7 as initial values. (1
The primary resistance and the secondary resistance estimated value R are calculated by the equations 2) and (13).
What is necessary is just to calculate 1 ^* and R2 ^* and output them to the sensorless vector controller 6.

^{R1 * = KR1Σ (I 2 -I0} 2) t + R1 ( ^{startup) ··· (12) R2 * =} KR2Σ (I 2 -I0 2) t + R2 ( startup) by this ... (13), the actual more There is an effect that the resistance fluctuation can be estimated as a value close to the resistance value.

When the current of the induction motor 1 is substantially constant, the resistance change coefficient calculator 8 omits the calculation of the time integral value of the square of the current, and starts the operation of the induction motor 1 input from the resistance measuring device 7. And the coefficient of change KR1 of the primary resistance and the secondary resistance as the resistance change per unit time obtained by dividing the difference between the primary resistance and the secondary resistance immediately after the stop by the operation time from the start to the stop.
KR2 may be calculated. In this case, the resistance fluctuation estimator 9a
May be calculated as the resistance change amount by multiplying the change coefficients KR1 and KK2 of the primary resistance and the secondary resistance calculated as the change amount per unit time by the elapsed time from the start.

Thus, there is an effect that the resistance fluctuation can be estimated with a small amount of calculation.

Further, in the first embodiment, the resistance
The primary resistance and the secondary resistance are measured by the resistance change coefficient calculator 8 to calculate the resistance change coefficients KR1 and KR2 of the primary resistance and the secondary resistance, and the resistance change estimator 9 calculates the primary resistance and the secondary resistance. Although the estimation values R1 ^* and R2 ^* are calculated, the primary resistance and the secondary resistance can be calculated independently, so that only one of them may be estimated.

That is, when both the primary resistance and the secondary resistance are used in the sensorless vector controller 6, both are estimated as described above. When only the primary resistance is used, the resistance measuring device 7, the resistance change coefficient calculator 8, The resistance variation estimator 9 may be configured to estimate only the primary resistance only for the primary resistance and to estimate only the secondary resistance when only the secondary resistance is used.

With the above configuration, it is possible to measure only the resistance value necessary for the control operation of the induction motor 1,
There is an effect that simplification of the resistance measurement at 76 and simplification of the calculations at the resistance change coefficient calculator 8 and the resistance variation estimator 9a can be achieved.

Also, assuming that the primary resistance and the secondary resistance change similarly,
Only the primary resistance value was measured by the resistance measuring instrument 7 and the measured 1
The resistance change coefficient KR1 of the primary resistance is calculated by the resistance change coefficient calculator 8 using the secondary resistance value, and the resistance change coefficient K of the secondary resistance is calculated.
R2 = KR1 may be set. Further, the reverse may be applied.

Second Embodiment 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 a 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, and 5b is A tuning controller for controlling a tuning by inputting a speed command which is an output from the speed command generator 4, a sensorless vector controller 6 for controlling the induction motor 1,
Reference numeral 7 denotes a resistance measuring device that measures the primary and secondary resistance of the induction motor 1 at the time of starting and stopping. Reference numeral 8 denotes a resistance change coefficient calculator for calculating the resistance change coefficient of the induction motor 1 based on the current detector 3 and the output of the resistance meter 7, and 11 denotes the output of the resistance meter 7 and the resistance change coefficient calculator 8. , And stores the relationship between the resistance change coefficient and the resistance value. 9a estimates the resistance fluctuation of the induction motor 1 based on the output of the current detector 3, the resistance measuring device 7 and the resistance characteristic storage 11. 10 is a resistance fluctuation estimator for starting and stopping when starting and stopping.
This is a control switch which is closed on the side and closed on the sensorless vector controller 6 side during operation, and is controlled by the tuning controller 5b.

Next, the operation of the control device for the induction motor according to the second embodiment will be described. In the first embodiment, the resistance change estimator 9a calculates the resistance change coefficient K calculated by the resistance change coefficient calculator 8 using the resistance measurement values immediately before the start and immediately after the stop.
The resistance fluctuation was estimated using R1 and KR2.
In, the resistance change coefficient for the resistance value is stored in the resistance characteristic storage unit 11, and the resistance change is estimated by the resistance change estimator 9a using the stored resistance change coefficients KR1 and KR2.

Here, assuming that the current I is flowing through the induction motor 1, it is considered that a heat quantity proportional to the square of I per unit time is generated from the induction motor 1 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 In addition, the change coefficients KR1 and KR2 of the secondary resistance have characteristics as shown in FIG. FIG. 4 (a) illustrates the relationship between the value related to the heat value of the induction motor and the resistance value, and FIG. 4 (b) illustrates the relationship between the value related to the heat 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 exercise cycle and stored in the resistance characteristic storage unit 11 according to the same operation principle as that of the first embodiment, and as a function of the resistance value during normal operation. By calling the resistance change coefficients KR1 and KR2, it is possible to set a coefficient that is more suitable for the actual resistance change.

First, at the time of startup when the speed command ωm ^* is input from the speed command generator 4 to the tuning controller 5b, the tuning controller 5b closes the control switch 10 to the resistance measuring device 7 side and further outputs a resistance measurement start signal. Output to the resistance measuring device 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 by the same method as that 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 5b, and simultaneously, the resistance change coefficient calculator 8, the resistance characteristic storage device 11, and the resistance variation. The measurement result is output to the estimator 9a. When the tuning controller 5b receives the resistance measurement completion signal output from the resistance measuring device 7, the tuning controller 5b operates to close the control switch 10 to the sensorless vector controller 6 side, and the tuning controller 5b outputs the signal from the sensorless vector controller 6. The operation of the induction motor 1 is started by the switching signal.

Thereafter, 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 stops after deceleration, a stop completion signal is output to the tuning controller 5b. . The tuning controller 5b outputs a resistance measurement start signal to the resistance measuring device 7 in response to the input of the stop completion signal, and when the resistance measurement starting signal is input, the resistance measuring device 7 induces again in the same manner as when starting. The measurement of the primary resistance and the secondary resistance of the electric motor 1 is started.

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 output to the resistance change coefficient calculator 8 at the same time. The resistance change coefficient calculator 8 includes a control signal output from the tuning controller 5b and the current detector 3
Current I of the induction motor 1 output from the
At the start and immediately after the start of the induction motor 1
The measured values of the secondary resistance and the secondary resistance are input, and the change coefficients KR1 and KR2 of the primary resistance and the secondary resistance per unit amount (I ² t = 1) are input in the same manner as described in the first embodiment. Is calculated and output to the resistance characteristic storage unit 11.

The resistance characteristic storage 11 stores the resistance change corresponding to the resistance closest to the resistance measured at startup measured by the resistance measuring device 7 among the resistance values and the resistance change coefficients stored in the resistance characteristic storage 11. The coefficient is output to the resistance fluctuation estimator 9a. The resistance change estimator 9a receives the resistance change coefficient output from the resistance characteristic storage 11, calculates the primary resistance and the secondary resistance by the same operation as in the first embodiment, and performs sensorless vector control. Output to the container 6. By repeating this series of operations, the resistance characteristic storage unit 11 stores the resistance change coefficients KR1 and KR2 for a plurality of resistance values, and stores a more detailed relationship between the resistance value and the resistance change coefficient. Also,
The relationship between the accumulated resistance value and the resistance change coefficient is used for the resistance estimation by the resistance variation estimator 9a, and 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 DC current is supplied to the induction motor 1 by the inverter 2, and the primary resistance and the secondary resistance are measured by the resistance measuring device 7. Next, in step S103, the resistance change coefficients KR1 and KR2 stored in the resistance characteristic storage unit 11 are referred to using the resistance value measured in step S102. Further, in step S104, the process proceeds to the actual operation cycle, which is the normal operation mode, and the movement of the induction motor 1 is started.
In step S104, the resistance values measured in step S102 are set as initial values, and the values of KR1 and KR1 referred to in step S103 are determined.
R2 and induced current flowing to the motor I than KR1ΣI ² t, KR
2ΣI ² t and the primary resistance and 2
The variation of the secondary resistance is estimated, and the sensorless vector controller 6 controls the inverter 2 using the estimated primary resistance and secondary resistance.

In step S105, a stop signal is given to the induction motor 1
The tuning controller 5b determines whether or not has stopped,
While the induction motor 1 is operating, the process returns to step S104. If a stop signal is given and the induction motor 1 stops, step S106
Then, the primary resistance and the secondary resistance of the induction motor 1 are measured by the inverter 2 again. Further, in step S107,
The difference between the primary resistance and the secondary resistance at the time of starting measured in step S102 and the primary resistance and the secondary resistance at the time of stopping measured in step S106 is integrated during the operation time of the actual operation cycle of the induction motor 1. ² is divided by t (time integral value of the current squared) to obtain the unit weight (i ² t = 1) the variation coefficient of the primary resistance and secondary resistance per KR1, KR2. Next, in step S108, the latest data calculated in step S107 is added to the relation data of the resistance change coefficient with respect to the resistance value stored in the resistance characteristic storage 11, or the conventional data is corrected using the latest data. I do. 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 at the start and immediately after the stop and the current detected by the current detector 3. A resistance change coefficient calculator 8 for calculating a change coefficient, and a relation between the resistance change coefficient and the resistance value by inputting the resistance value measured by the resistance measuring device 7 and the resistance change coefficient calculated by the resistance change coefficient calculator 8. The resistance characteristic storage unit 11 stores the current detected by the current detector 3, the resistance value at the time of startup measured by the resistance measurement unit 7, and the resistance change coefficient output from the resistance characteristic storage unit 11. Since the resistance fluctuation estimator 9a for estimating the resistance fluctuation based on is provided,
The effect that the resistance fluctuation of the induction motor 1 can be satisfactorily estimated without setting the thermal resistance, the thermal time constant, and the like in advance, and even when the resistance value at the time of startup greatly differs from the previous resistance value. There is.

In the induction motor control device according to the second embodiment, the relationship between the resistance change coefficients KR1 and KR2 corresponding to the resistance value is stored and accumulated, and the resistance is estimated using the stored relationship. The relationship between the resistance change coefficients KR1 and KR2 corresponding to the resistance values is stored and accumulated using the current detected by the current detector 3 as a parameter, and the current change during the actual operation cycle and the resistance change coefficient KR1 corresponding to the resistance value. , K
The resistance may be estimated with reference to the relationship of R2.

As shown in FIG. 4, the resistance value of the induction motor 1 is ΔI ²
It shows a first-order lag characteristic with respect to 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 value rise are in a proportional relationship, As shown in FIG. 7 (a), the characteristic of the resistance value with respect to ΣI ² t is obtained using the current I of the induction motor 1 as a parameter, and the relationship of the resistance change coefficient is as shown in FIG. 7 (b). It becomes a characteristic using I as a parameter.

Further, FIG. 8 shows the characteristic of FIG. 7 (b) as a relationship between the resistance value and the resistance change coefficient. Therefore,
According to the same operating principle as the induction motor control device shown in FIG. 3, the resistance change coefficients of the primary resistance and the secondary resistance are calculated for each actual operation cycle, and the current is stored as a parameter in the resistance characteristic storage 11a and stored. Then, during the operation of the actual operation cycle, if the resistance change coefficients KR1 and KR2 are called as a function with respect to the resistance value using the current as a parameter, a coefficient corresponding to the actual resistance change for a plurality of load states of the induction motor can be set. .

FIG. 9 is a block diagram showing another mode 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 indicate the same or corresponding parts. In FIG.
Reference numeral 11a denotes a resistance characteristic storage device that receives the resistance measurement device 7 and the output of the resistance change coefficient calculator 8 and stores the relationship between the resistance change coefficient and the resistance value using the current detected by the current detector 3 as a parameter.

The resistance characteristic memory 11a stores the change coefficients KR1 and KR2 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, and operates so as to store the relationship between the resistance value and the resistance change coefficient as shown in FIG. 8 using the input current as a parameter.

The resistance characteristic storage unit 11a stores the resistance change coefficient characteristic data stored in correspondence with the current value closest to the current detected by the current detector 3 among the stored resistance value and resistance change coefficient. Then, 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 output to the resistance fluctuation estimator 9a. The resistance variation estimator 9a receives the resistance change coefficient output from the resistance characteristic storage 11a and estimates the primary resistance and the secondary resistance by the same operation as the induction motor control device described with reference to FIG. Is calculated and output to the sensorless vector controller 6. By repeating this series of operations, the resistance characteristic storage unit 11a stores the resistance change coefficients KR1 and KR2 for a plurality of resistance values, and stores a more detailed relationship between the resistance value and the resistance change coefficient. Further, it is used for the resistance estimation by the resistance fluctuation estimator 9a, so that highly accurate resistance estimation can be realized. Further, since the relationship between the resistance change coefficient and the resistance value is stored and accumulated using 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, and to set the load size. Irrespective of this, there is an effect that a highly accurate resistance value can be estimated.

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 output to the resistance fluctuation estimator 9a. During operation, the estimated value of the resistance output from the resistance fluctuation estimator 9a is input to the resistance characteristic storage unit 11a, and the resistance change coefficient corresponding to the resistance value closest to the resistance value is sequentially determined. The output may be output to the fluctuation estimator 9a. As a result, even when the continuous operation state continues for a long time and the resistance change coefficient changes, the optimum value is used in accordance with the change in the estimated resistance value, and more accurate estimation of the resistance value is performed. There is an effect that can be.

Third Embodiment In the second embodiment, the relationship between the resistance value and the resistance change coefficient is stored while performing the normal operation. However, prior to the normal operation, the test operation mode is set as the test operation mode when the induction motor 1 is heated. Perform cycle operation at time intervals shorter than the constant,
The resistance change coefficients for a plurality of resistance values in the temperature range of the induction motor 1 that can be taken in the normal operation state may be stored in advance.

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 those 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 output from the speed command generator 4 and an operation mode command output from the operation mode setting device 12. This is a tuning controller that controls tuning by inputting.

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 unit 12, the tuning controller 5c switches so as to have a predetermined operation cycle for testing. next,
When the speed command ωm ^* is input from the speed command generator 4,
The tuning controller 5c closes the control switch 10 to the resistance measuring device 7 and outputs a resistance measurement start signal to the resistance measuring device 7. When the resistance measuring device 7 receives the resistance measurement start signal from the tuning controller 5c, the primary and secondary resistances of the induction motor 1 are controlled.
Start measurement of the next resistance value. Note that the resistance measuring device 7 measures the resistance value by the same method as that 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 5c, and at the same time, the resistance change coefficient calculator 8, the resistance characteristic storage device 11, and the resistance fluctuation. The measurement result is output to the estimator 9a. When the tuning controller 5c receives the resistance measurement completion signal output from the resistance measuring device 7, the tuning controller 5c operates to close the control switch 10 to the sensorless vector controller 6 side, and the tuning controller 5c outputs the signal from the sensorless vector controller 6. The operation of the induction motor 1 is started by the switching signal.

Thereafter, after a lapse of time shorter than the thermal time constant of the induction motor, the induction motor 1 is decelerated and stopped, and a stop completion signal is output 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 when the resistance measurement start signal is input, the resistance measurement device 7 stops again in the same manner as when starting. The measurement of the primary resistance and the secondary resistance of the induction motor 1 at the time is started.

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. The resistance change coefficient calculator 8 is configured to control the control signal output from the tuning controller 5c and the current detector 3
Current I of the induction motor 1 output from the
At the start and immediately after the start of the induction motor 1
The measured values of the secondary resistance and the secondary resistance are input, and the change coefficients KR1 and KR2 of the primary resistance and the secondary resistance per unit amount (I ² t = 1) are input in the same manner as described in the first embodiment. Is calculated and output to the resistance characteristic storage unit 11. Further, the tuning controller 5c outputs a control signal so that the above-described cycle is repeatedly performed 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 device 11 has a resistance change coefficient K for a plurality of resistance values.
R1 and KR2 are stored.

Next, when a predetermined driving cycle for testing is completed,
The tuning controller 5c switches from the test operation mode to the normal operation mode. From the next start-up, by the same operation as described in the second embodiment, the resistance characteristic storage 11 stores the resistance measured value at the start-up measured by the resistance measuring device 7 out of the stored resistance value and resistance change coefficient. Is output to the resistance fluctuation 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 as described in the first embodiment, and performs sensorless operation. Output to the vector controller 6.

Thereby, 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 estimated well. Further, it is possible to omit the resistance measurement at the time of start-up and immediately after the stop, and there is an effect that the start-up can be accelerated.

Note that the resistance characteristic storage unit 11 stores a resistance change coefficient for a plurality of resistance values stored in a predetermined test operation mode as a function interpolated by performing a polynomial approximation or a function approximation using a least-squares method, etc. May be.

Thereby, 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.

In addition, a resistance fluctuation estimator
9a, the resistance value immediately after the stop is estimated by the resistance measuring device 7 and the resistance value immediately after the stop is compared.
If these differences exceed a predetermined value, the resistance characteristic storage 11
May be configured so as to correct the function of the resistance value and the resistance change coefficient stored by.

As a result, even when a temperature difference between the induction motor temperature and the ambient temperature or a change in the flow rate of the surrounding air due to a change in air temperature or an environmental change in the vicinity of the motor occurs, the characteristic stored in the resistance characteristic storage unit 11 is obtained. Can always be corrected so as to match the actual characteristics, and the effect is that the resistance fluctuation can be estimated in good condition.

Furthermore, during the operation of the normal actual operation cycle, the resistance variation estimator 9a refers to the resistance change coefficient stored in the sequential resistance characteristic storage 11 using the resistance value estimated by the resistance variation estimator 9a. The resistance value may be estimated using the referred resistance change coefficient.

As a result, it is 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 has an effect that the resistance change can be well estimated even when the resistance change amount from the start is large. is there.

Embodiment 4 In the above-described embodiment, the resistance value change due to the temperature fluctuation of the induction motor 1 is estimated, and the inverter 2 is controlled using the resistance value estimated by the sensorless vector controller 6, but Induction motor 1 from resistance change
May be configured to estimate the temperature rise.

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 for estimating the temperature of the induction motor 1 by inputting the resistance estimation value output from the resistance fluctuation estimator 9a, 5d is a speed command which is an output from the speed command generator 4, and The tuning controller controls the tuning by inputting the estimated temperature of the induction motor 1 output from the temperature estimator 13.

The temperature estimator 13 stores in advance the resistance values of the primary and secondary resistances 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 change specific to the materials of the primary conductor and the secondary conductor of the induction motor 1 are determined. From the coefficients, the temperatures of the primary conductor and the secondary conductor of the induction motor 1 are estimated. 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 t0 ° C. is R1 (t0), the resistance fluctuation estimator
The temperature t 1 ° C of the induction motor 1 when the resistance value output from 9a is R1 (t1) can be estimated by equation (14).

Further, the tuning controller 5d receives the temperature estimation value of the induction motor 1 output from the temperature estimator 13 and
When the estimated temperature rises above a preset temperature, the operation is performed to stop the induction motor 1 to prevent burning.

Here, when measuring the resistance value of the induction motor 1 at a generally known temperature, when the induction motor 1 is in a temperature state substantially equal to the ambient temperature without providing a special detector such as a thermocouple in the induction motor 1. What is necessary is just to set the measured value of the ambient temperature at that time by measuring the resistance value with the resistance measuring device 7 as the temperature of the induction motor 1.

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

As described above, according to the present invention, the resistance change coefficient that calculates 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 A computing unit 8, a resistance characteristic storage unit 11 that receives the resistance value measured by the resistance measuring unit 7 and the resistance change coefficient calculated by the resistance change coefficient computing unit 8 and stores the relationship between the resistance change coefficient and the resistance value. And a resistance change for estimating the resistance change based on 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 unit 11. Since the estimator 9a and the 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, the thermal resistance, thermal time constant, etc. of the induction motor are set in advance. Without induction The effect is that the temperature rise of the machine can be estimated.

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, since the wiring from the inverter 2 to the induction motor 1 is usually selected and laid so that the temperature does not rise too much, the temperature change is set in advance in the temperature estimator 13 by the wiring resistance Rh, and the wiring resistance Rh is set. Is assumed to be constant during operation, and instead of equation (14), (1
5) Equation may be used.

Here, the resistance value of the wiring from the inverter 2 to the induction motor 1 may be set to a value measured by a low resistance measuring device such as a bridge or a milliohm meter. If it is known in advance by data or the like, it may be obtained by calculation by multiplying it by the wiring length and set.

Thereby, even if the wiring resistance from the inverter 2 to the induction motor 1 is relatively large, the primary resistance fluctuation of the induction motor 1 can be more accurately estimated, whereby the temperature rise of the induction motor 1 can be satisfactorily estimated. There is an effect that can be.

In all of the above-described embodiments, the inverter 2
There are many known resistance measurement methods such as single-phase application, resistance measurement by low-voltage three-phase application, and the like. It goes without saying that the control device for an induction motor of the present invention can be configured.

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

INDUSTRIAL APPLICABILITY As described above, the control device for an induction motor and the control method for an induction motor according to the present invention, for example, estimate a resistance change due to a temperature change during operation of a winding of the induction motor. ,
The present invention is suitable for an induction motor control device and an induction motor control method for performing vector control and sensorless vector control so that the induction motor follows the command speed based on the estimated winding resistance value.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-117683 (JP, A) JP-A-6-30587 (JP, A) JP-A-6-165562 (JP, A) JP-A-58-58 215992 (JP, A) JP-A-60-16184 (JP, A) JP-A-61-76090 (JP, A) JP-A-61-231890 (JP, A) JP-A-63-249486 (JP, A) JP-A-56-86089 (JP, A) JP-A-62-79380 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 5/408-5/412 H02P 7/628 -7/632 H02P 21/00 H02M 7/42-7/98

Claims (14)

(57) [Claims] 1. A first operation cycle in which the operation of an induction motor is started (after correction) and is stopped after a predetermined period of operation, and a second operation in which the operation of the induction motor is started again after the first operation cycle. An operation cycle, and a control device for the induction motor that controls the operation of the induction motor so as to include at least: an inverter that supplies a voltage to the induction motor; and a resistance measurement unit that measures a winding resistance value of the induction motor. Based on a difference between the winding resistance measured before and after the first operation cycle and a value related to a heat value of the induction motor generated during the first operation cycle, per unit amount of this value. Resistance change coefficient calculating means for calculating a resistance change coefficient representing the degree of change in the winding resistance of the winding; and starting winding resistance measured by the resistance measuring means at the start of the second operation cycle. Resistance variation estimating means for outputting an estimated winding resistance value estimated based on a value and a value related to a heat value of the induction motor during the second operation cycle and the resistance change coefficient; and the estimated winding resistance value. And a control unit for controlling the inverter using the control unit, wherein the value related to the heat value corresponds to the heat value itself of the induction motor or a predetermined physical value that varies according to the heat value. Control device for induction motor. 2. The resistance change coefficient calculation 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 change estimation means includes: 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 second operation cycle is calculated based on a current value supplied to the induction motor. . 3. A resistance change coefficient calculating means calculates a value related to a heat generation amount of the induction motor generated during the first operation cycle based on a torque command value instructed to the induction motor. 2. The induction motor according to claim 1, wherein a value related to a heat value of the induction motor generated during the second operation cycle is calculated based on a torque command value instructed to the induction motor. Control device. 4. The resistance estimating means is configured to determine the stop winding resistance measured by the resistance measuring means when the first operation cycle is stopped as the start winding resistance measured at the start of the second operation cycle. The control device for an induction motor according to claim 1, wherein an estimated winding resistance value during the second operation cycle is output. 5. A first operation cycle in which the operation of the induction motor is started (after correction) and is stopped after a predetermined period of operation, and a second operation in which the operation of the induction motor is started again after the first operation cycle. An operation cycle, and a control device for the induction motor that controls the operation of the induction motor so as to include at least: an inverter that supplies a voltage to the induction motor; and a resistance measurement unit that measures a winding resistance value of the induction motor. , First
Based on the difference between the winding resistance values measured before and after the operation cycle and a value related to the calorific value of the induction motor generated during the first operation cycle. Resistance change coefficient calculating means for calculating a resistance change coefficient representing a degree of change in resistance; storing a relationship between the resistance change coefficient and the winding resistance value; A resistance characteristic storage unit that outputs a resistance change coefficient by referring to the relationship stored based on the startup winding resistance value measured by the above, and an output from the resistance characteristic storage unit based on the startup winding resistance value. Resistance variation estimating means for estimating and outputting an estimated winding resistance value from the obtained resistance change coefficient and a value relating to the heat value of the induction motor in the second operation cycle, and using the estimated winding resistance value. Control the inverter And control means, the value relating to the amount of heat generated, the control device of an induction motor, characterized in that corresponding to a predetermined physical value which varies as a function of the calorific value itself or emitting heat of the induction motor. 6. A resistance characteristic storage means for storing a relationship between a resistance change coefficient and a winding resistance value using a current value during a first operation cycle as a parameter, and a resistance measurement means for starting the second operation cycle. 6. The control device for an induction motor according to claim 5, wherein a resistance change coefficient corresponding to the measured start-up winding resistance value is output with reference to the current value in the second operation cycle. 7. The resistance characteristic storage means approximates a function 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 the control device stores the information. 8. The resistance change coefficient calculating means compares the estimated winding resistance estimated at the time of stopping the second operation cycle with the winding resistance at stop measured at the time of stopping the second operation cycle by the resistance measuring means. And wherein when the difference exceeds a predetermined value, the relation between the winding resistance value and the resistance change coefficient stored in the resistance characteristic storage means is corrected.
The control device for an induction motor according to Item. 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 determined 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 a temperature estimating means for estimating a temperature of the winding from a relationship with a value. 10. The temperature estimating means stores the resistance value of the wiring from the inverter to the induction motor in advance, 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. 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, and the control means stops the operation of the inverter. 10. The control device for an induction motor according to claim 9, wherein: 12. Prior to the first and second driving cycles,
The difference between the winding resistance measured by the resistance measuring means at the start and stop of each operation cycle of a predetermined operation cycle that repeats a set number of times by the resistance change coefficient calculation means and the difference generated during each of the operation cycles. The resistance change coefficient of the winding resistance per unit amount is calculated for each of the operation cycles from the value related to the calorific value of the induction motor thus obtained, and the resistance change coefficient for each of the operation cycles and the resistance change coefficient are stored in resistance characteristic storage means. 6. The control device for an induction motor according to claim 5, further comprising an operation mode setting means for storing a relationship with a winding resistance value. 13. Based on a difference between winding resistance values measured before and after an operation cycle (after correction) and a value related to a heat value of an induction motor generated during the operation cycle, this value is calculated per unit amount. A coefficient calculation step of calculating a resistance change coefficient representing the degree of change of the winding resistance of the coil, a startup resistance measurement step of measuring a startup winding resistance at the start of the next operation cycle, and the startup winding resistance. A winding resistance value estimating step of outputting an estimated winding resistance value estimated from the resistance change coefficient and a value related to a calorific value of the induction motor during the operation cycle, based on the estimated winding resistance value. A control step of controlling an inverter that drives the induction motor; and a stop resistance measurement step of measuring a stop winding resistance value when the operation cycle is stopped, wherein the value related to the heat value is the induction motor. Control method for an induction motor, characterized in that corresponding to a predetermined physical value which varies as a function of the calorific value itself or emitting heat. 14. Based on a difference between winding resistance values measured before and after an operation cycle (after correction) and a value related to a heat value of an induction motor generated during the operation cycle, this value is calculated per unit amount. A coefficient calculating step of calculating a resistance change coefficient representing a degree of change of the winding resistance of the winding, a storage step of storing a relationship between the winding resistance and the resistance change coefficient, and a start-up winding at the start of a next operation cycle. A startup resistance measurement step of measuring a resistance value; a coefficient extraction step of obtaining a resistance change coefficient corresponding to the startup winding resistance by referring to a relationship between the winding resistance and the resistance change coefficient; A winding resistance estimating step of outputting an estimated winding resistance value estimated from a resistance change coefficient corresponding to the starting winding resistance based on the wire resistance and a value related to a calorific value of the induction motor during the operation cycle; Said A control step of controlling an inverter that drives the induction motor based on a winding resistance value; anda stop resistance measurement step of measuring a stop winding resistance value when the operation cycle is stopped. A method for controlling an induction motor, wherein the related value corresponds to a heat value itself of the induction motor or a predetermined physical value that varies according to the heat value.