JP2000041400A - Controller for induction motor for compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the vibration level of an induction motor, even when the motor is operated at a low frequency by using the sum of an average torque current command value and a load torque current command value which has the same period as the rotating period at an estimated speed as a torque current command value. SOLUTION: When, for example, the frequency of an induction motor for compressor drops to <=30 Hz, a load torque current commanding device conducts frequency analysis on an estimated speed ωme'. Since the estimated speed ωme' contains a pulsating component, a speed fluctuating period component, namely, an estimated average rotating speed component (period T) having a large peak is obtained. Then the amplitude of a load torque current, which fluctuates due to the ambient temperature, is optimized from the fluctuation of the estimated speed ωme'. In addition, the period pattern of the load torque current which has the amplitude optimized in the one-period pattern of the load torque current corresponding to a command speed ωme* and the load torque current command value having the period T of the estimated average rotating speed is generated. Moreover, a phase timing such that the varying width of the estimated speed ωme' becomes smaller is decided and outputted from the load torque current commanding device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an induction motor for a compressor, and more particularly to a control device for controlling a supply current of the induction motor for a compressor.

[0002]

2. Description of the Related Art Conventionally, there is a one-piston rotary compressor as a compressor used in home air conditioners and the like, and an induction motor is used to drive the compressor. As a driving method, a V / f control method is often used. In this one-piston rotary compressor, the cycle of suction, compression and discharge of the refrigerant is performed for each rotation, but as shown in FIG. 5, the fluctuation of the compression torque per rotation is very large. On the other hand, the induction motor side under the V / f control generates a substantially constant motor torque having a fluctuation smaller than the fluctuation of the compression torque. It is known that the difference between the compression torque and the motor torque becomes an exciting force and is a major cause of vibration (for example, Transactions of the Japan Society of Mechanical Engineers (C), Vol. 49, No. 444 (1983) ), Pages 1346 to 1353).

In particular, when the compressor is driven at a low frequency of 30 Hz or less, the vibration of the compressor becomes extremely large, so that the minimum drive frequency is limited in view of the strength of the compressor and the induction motor that drives the compressor. Come. On the other hand, from the viewpoint of energy saving, there is a demand to lower the minimum drive frequency beyond this limit in order to obtain an appropriate drive state. In order to meet this demand, the motor torque may be controlled in accordance with the fluctuation of the compression torque to eliminate the difference between the compression torque and the motor torque. As the control method, specifically, for example, a method described in JP-A-3-239193 and a method described in JP-A-5-212178 are known.

[0004]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 3-239 is disclosed.
In the device described in Japanese Patent No. 193, a signal corresponding to the rotation angle of the compressor is detected, and the motor torque is controlled based on the position signal to reduce vibration. In this embodiment, a position detector is required to obtain a position signal corresponding to the rotation angle. In addition, Japanese Patent Application Laid-Open No. 5-31217
In the device described in Japanese Patent Application Publication No. 8 (1994), the motor torque is controlled based on the displacement of the valve of the discharge port to reduce vibration. In order to obtain this displacement, a displacement detector is required. In each case, a detector that accurately obtains information relating to the rotational position is used, and there has been a problem that vibration cannot be reduced without positional information detected using the detector.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and it is an object of the present invention to control a motor torque on the basis of information on an average rotational speed of an induction motor for driving a compressor.
An object of the present invention is to provide a control device for an induction motor for a compressor that reduces vibration of the compressor. That is, an object of the present invention is to provide a control device for an induction motor for a compressor, which can reduce the vibration of the compressor without a position detector or a displacement detector for obtaining accurate information on the rotational position.

[0006]

A control device for an induction motor for a compressor according to the present invention comprises a compressor for compressing a refrigerant that generates a pulsating torque synchronized with rotation, and a three-phase induction motor for driving the compressor. A speed estimator that estimates the actual speed of rotation of the three-phase induction motor and outputs an estimated speed; and a torque current command value that is a torque current component of a primary alternating current group supplied to a stator of the three-phase induction motor. A torque current commander that outputs an excitation current command value that is an excitation current component of the primary AC current group, and the three-phase induction from the torque current command value and the excitation current command value. A slip frequency calculator for calculating a slip frequency of the motor; a primary AC power source for outputting a primary AC current command value according to the torque current command value, the exciting current command value, the estimated speed, and the slip frequency; A commander, a current detector group for detecting each of the primary AC current groups, and a current for controlling the primary AC current group such that the outputs of the current detector groups respectively correspond to the corresponding primary AC current command values. A controller;
A power converter for supplying a primary AC voltage group to a stator of the three-phase induction motor in accordance with an output of the current controller, and a control device for the induction motor for a compressor, wherein the torque current commander includes: The sum of an average torque current command value calculated according to the command speed of the three-phase induction motor and the estimated speed, and an additional torque current command value having the same cycle as the rotation cycle of the estimated speed is calculated as the torque current. It is output as a command value.

Thus, a torque current commander for outputting a torque current command value having the same cycle as the average rotation cycle of the induction motor is provided. Therefore, by applying a torque current corresponding to the load fluctuation synchronized with the rotation of the induction motor, a motor output suitable for the load state can be obtained. As a result, rotation speed fluctuations of the induction motor are suppressed, and vibration can be reduced.

In the control device for an induction motor for a compressor having the above-described configuration, the speed estimator includes at least one of a primary AC current group and a primary AC voltage group of the three-phase induction motor and an electric motor of the three-phase induction motor. It is preferable to output an estimated speed based on the frequency of the pulsation component of any of the estimated speed, the estimated slip frequency, or the estimated torque calculated using the constant.

Further, a control device for an induction motor for a compressor according to another aspect of the present invention includes a compressor for compressing a refrigerant that generates a pulsating torque synchronized with rotation, and a three-phase induction motor that drives the compressor. A speed detector for detecting the actual rotation speed of the three-phase induction motor, and a torque current command for outputting a torque current command value that is a torque current component of a primary AC current group supplied to a stator of the three-phase induction motor. An excitation current commander that outputs an excitation current command value that is an excitation current component of the primary AC current group, and calculates a slip frequency of the three-phase induction motor from the torque current command value and the excitation current command value. A slip frequency calculator, a primary AC current command device that outputs a primary AC current command value according to the torque current command value, the exciting current command value, the output of the speed detector, and the slip frequency. A current detector group that detects each of the primary AC current groups, and a current controller that controls the primary AC current group so that the outputs of the current detector groups respectively correspond to the corresponding primary AC current command values. A power converter for supplying a primary AC voltage group to a stator of the three-phase induction motor in accordance with an output of the current controller, a control device for the induction motor for a compressor, An average torque current command value calculated according to a command speed of the three-phase induction motor and an output of the speed detector, and an average rotation period of the three-phase induction motor obtained by time-averaging the output of the speed detector. And outputting the sum of the additional torque current command value and the additional torque current command value having the same cycle as the torque current command value.

[0010] The control device for an induction motor for a compressor having this configuration also includes a torque current command device that outputs a torque current command value having the same cycle as the average rotation cycle of the induction motor. Therefore, by applying a torque current corresponding to the load fluctuation synchronized with the rotation of the induction motor, a motor output suitable for the load state can be obtained. As a result, rotation speed fluctuations of the induction motor are suppressed, and vibration can be reduced.

Further, a control device for an induction motor for a compressor according to another aspect of the present invention includes a compressor for compressing a refrigerant generating a pulsating torque synchronized with rotation, and a three-phase induction motor for driving the compressor. A speed estimator that estimates the actual rotation speed of the three-phase induction motor and outputs the estimated speed, and a torque current command value that is a torque current component of a primary AC current group supplied to a stator of the three-phase induction motor. A torque current command device for outputting, an exciting current command device for outputting an exciting current command value that is an exciting current component of the primary AC current group, and the three-phase induction motor based on the torque current command value and the exciting current command value. A slip frequency calculator that calculates the slip frequency of
According to the torque current command value, the exciting current command value, the command speed of the three-phase induction motor and the slip frequency,
A primary AC current commander that outputs the primary AC current command value, a current detector group that detects each of the primary AC current groups, and an output of the current detector group that matches a corresponding primary AC current command value. And a power converter for supplying the primary AC voltage group to the stator of the three-phase induction motor according to the output of the current controller. A control device for an induction motor, wherein the torque current command device has an average torque current command value that is predetermined according to a command speed of the three-phase induction motor, and has the same cycle as a rotation cycle of the estimated speed. It is characterized in that a sum with an additional torque current command value is output as the torque current command value.

Further, a control device for an induction motor for a compressor according to another aspect of the present invention includes a compressor for compressing a refrigerant that generates a pulsating torque synchronized with rotation, and a three-phase induction motor that drives the compressor. A speed estimator that estimates the rotational speed of the three-phase induction motor and outputs an estimated speed, and outputs a torque current command value that is a torque current component of a primary AC current group supplied to a stator of the three-phase induction motor. A torque current command device, an exciting current command device that outputs an exciting current command value that is an exciting current component of the primary AC current group, and slipping of the three-phase induction motor based on the torque current command value and the exciting current command value. A slip frequency calculator for calculating a frequency, the torque current command value, the exciting current command value, the three-phase induction motor command speed and the slip frequency, and the primary AC current command value. A primary AC current commander to output, a current detector group to detect each of the primary AC current groups, and the primary AC current group so that the outputs of the current detector groups match the corresponding primary AC current command values, respectively. And a power converter that supplies the primary AC voltage group to the stator of the three-phase induction motor according to the output of the current controller. The torque current command device outputs the torque current command value having a cycle pattern having the same cycle as the rotation cycle of the estimated speed.

The control device for an induction motor for a compressor having such a configuration also includes a torque current command device that outputs a torque current command value having the same cycle as the average rotation cycle of the induction motor. Therefore, by applying a torque current according to the load fluctuation synchronized with the rotation of the induction motor,
The motor output suitable for the load condition is obtained. As a result, fluctuations in the rotation speed of the induction motor are suppressed, and vibration can be reduced.

In the control apparatus for an induction motor for a compressor having the above-described configuration, the speed estimator includes at least one of a primary AC current group and a primary AC voltage group of the three-phase induction motor and an electric signal of the three-phase induction motor. It is preferable to output the frequency of the pulsation component of any of the estimated speed, the estimated slip frequency and the estimated torque calculated using the constant as the estimated speed.

[0015] In the control device for an induction motor for a compressor having the above-described four configurations, the torque current command device may include an additional torque current command value having the same cycle as the rotation cycle of the estimated or detected speed of the three-phase induction motor. Alternatively, it is preferable that the torque current command value is generated when the frequency of the primary AC current command value is smaller than a predetermined value.

Further, the torque current commander is configured to calculate an estimated speed and an estimated slip calculated using at least one of a primary AC current group and a primary AC voltage group of a three-phase induction motor and an electrical constant of the three-phase induction motor. Frequency or estimated torque,
Alternatively, it is preferable to determine the phase timing for giving the additional torque current or the periodic pattern of the torque current according to any change in the detection speed.

The torque current commander is configured to calculate an estimated speed and an estimated torque calculated using at least one of a primary AC current group and a primary AC voltage group of a three-phase induction motor and an electrical constant of the three-phase induction motor. It is preferable to change the amplitude of the additional torque current or the periodic pattern of the torque current so that the variation width of either the magnitude of the secondary magnetic flux or the detection speed becomes equal to or less than a predetermined value.

The torque current commander changes at least the additional torque current or the amplitude of the periodic pattern of the torque current at a predetermined change rate or less, and at least one of the primary AC current group and the primary AC voltage group of the three-phase induction motor. Estimated speed calculated using one and the electrical constants of the three-phase induction motor,
It is preferable to change the amplitude of the additional torque current or the periodic pattern of the torque current such that the fluctuation range of any of the estimated torque, the magnitude of the secondary magnetic flux, or the detected speed is equal to or less than a predetermined value.

Further, after the torque current commander starts changing the amplitude of the periodic pattern of the additional torque current at a predetermined change rate or less, at least one of the primary AC current group and the primary AC voltage group of the induction motor and the induction motor are controlled. The periodic pattern of the additional torque current so that a fluctuation width of any of the estimated speed, the estimated torque or the magnitude of the secondary magnetic flux, or the detected speed calculated using the electric constant of the motor is equal to or less than a predetermined value. After the amplitude is changed, the average torque current command keeps the value before starting to change the amplitude of the periodic pattern of the additional torque current at a predetermined rate or less until a predetermined period elapses. Is preferred.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS.

Embodiment 1 FIG. 1 is a block diagram showing a configuration of a control device for an induction motor for a compressor according to Embodiment 1 of the present invention. The speed of rotation of the three-phase induction motor 12 that drives the compressor 13 by the command speed generator 1 (hereinafter simply referred to as speed)
Is output as a command speed ωme *. The exciting current command device 2 outputs a predetermined exciting current command value _{I1d *} . The torque current command device 3 includes an additional torque current command device 31, an average torque current command device 32, and an adder 33. The command speed ωme * and the estimated speed ωme ^ estimated by the speed estimator 14 for estimating the actual speed of the three-phase induction motor are the average torque current commander 32 in the torque current commander 3.
And outputs an average torque current command value by, for example, performing PI control so that the estimated speed ωme ^ follows the command speed ωme *.

On the other hand, the speed command value ωme * and the estimated speed ωme ^ are input to the additional torque current command device 31 to output the additional torque current command value. Details of the operation of the additional torque current command device 31 will be described later. The average torque current command value and the additional torque current command value are added by the adder 33,
It is output from the torque current command device 3 as a torque current command value _{I1q *} . Further, the slip frequency calculator 4 calculates the slip frequency ωs using the excitation current command value I _{1d *} , the torque current command value I _{1q *,} and a preset electric constant of the three-phase induction motor. Output. The estimated speed ωme ^ and the slip frequency ωs are added by the adder 5 to become the primary frequency ω0, and the primary frequency ω0 is integrated by the integrator 6 to become the phase command value θ.

Exciting current command value I _{1d *} , torque current command value I
_{1q *} and the phase command value θ are input to the primary current command device 7.
The primary current command device 7 has a rotating / stationary coordinate converter 71 and a two-phase /
A three-phase converter 72 is connected. The rotary / stationary coordinate converter 71 converts a DC excitation current command value I _{1d *} and a torque current command value I _{1q *} into a two-phase AC current command value. Then, the two-phase / three-phase converter converts the current value into a three-phase AC current command value.

In the current controller 8, the current detector groups 9a to 9
c so that the motor current detected in step c. follows the primary current command value output from the primary current command device 7.
The command value given to 0 is controlled. The converter 11 converts AC into DC and supplies the DC to the power converter 10. Then, according to the command value of the current controller 8, the power converter 10 supplies a voltage to the three-phase induction motor 12 to flow a current. on the other hand,
The speed estimator 14 uses at least one of the primary AC current group and the primary AC voltage group of the three-phase induction motor 12 and a preset electric constant of the three-phase induction motor,
The rotational speed of the three-phase induction motor 12 is estimated.

If the additional torque current commander 31 is not provided, the compressor is driven by the well-known sensorless vector control of the induction motor. Vector control is control that can independently control the rotation speed and torque of an induction motor.
For example, control can be performed to keep the speed constant even when the load torque fluctuates. However, in the conventional sensorless vector control, there is a limit to the response performance of the speed control to the load torque fluctuation. For example, when the rotation speed is controlled at 50 Hz, the response performance of the control is 1/10, which is about 5 Hz. Therefore, vibration occurs due to load fluctuation synchronized with rotation.
In a compressor such as a piston type rotary compressor, it is difficult to completely control the speed in a low frequency operation of 30 Hz or less where vibration is a problem. Therefore, even if the sensorless vector control is applied to a compressor such as a one-piston rotary compressor as it is, no significant improvement in vibration reduction is obtained as compared with the conventional V / f control.

Therefore, the control device for the induction motor for the compressor according to the first embodiment obtains the rotation speed information of the three-phase induction motor. Using this speed information, the additional torque current command device 31 outputs an additional torque current command value for adjusting the excess or deficiency of the motor torque with respect to the compression torque fluctuation.
This additional torque current command value bridges the torque difference between the compression torque and the motor torque, thereby bringing the compression torque and the motor torque as close as possible. By doing so, even during low-frequency motion, fluctuations in the rotation speed of the three-phase induction motor can be reduced, and as a result, vibration can be significantly reduced.

Here, the operation of the additional torque current commander 31 will be described with reference to the flowchart of FIG. When the frequency decreases to a low frequency at which vibration becomes a problem, for example, 30 Hz or less, the additional torque current commander 31
Of each step. First, the estimated speed ωme ^ is subjected to frequency analysis (step S1). Since there is a pulsating component in the estimated speed ωme ^, a component of the speed fluctuation period, that is, a component of the estimated average rotation speed is obtained with a large peak in this analysis (step S2). The cycle of the estimated average rotation speed is T. Then, the amplitude of the additional torque current that fluctuates due to the influence of the ambient temperature is optimized from the amplitude of the fluctuation of the estimated speed ωme ^ (step S3). Further, a cycle pattern of the additional torque current having the amplitude optimized by the one cycle pattern of the additional torque current corresponding to the command speed ωme * is generated (step S4). Then, an additional torque current command value with the cycle set to T is generated (step 5).
Then, a phase timing at which the fluctuation width of the estimated speed ωme ^ becomes small, for example, a phase timing at which the pulsation of the estimated speed becomes opposite to that of the estimated speed is determined and output from the additional torque current commander 31 (step S6).

The temporal change of the torque current command value, the compression torque, the motor torque, the rotation speed and the estimated speed when the additional torque current command value generated in this way is not added to the three-phase induction motor 12 and when it is added. Is shown in FIG. The left half of the vertical dashed line in FIGS. 3A, 3B, and 3C shows the case where the additional torque current command value is not added, and the right half shows the case where the additional torque current command value is added. When the additional torque current command value is not added, as shown in FIG. 3A, the torque current command value _{I1q *} is a constant value of only the average torque current command value. Since the estimated speed is also a substantially constant average value, the primary current command value has a constant amplitude and frequency. Therefore, as shown in FIG. 3B, a difference is generated between the compression torque and the motor torque, and as a result, as shown in FIG. 3C, it appears as a rotation speed fluctuation of the three-phase induction motor 12. When the additional torque current command value as shown in FIG. 3A is added, as shown in FIG. 3B, the difference between the motor torque and the compression torque becomes smaller, and as shown in FIG. As described above, the rotation speed fluctuation of the three-phase induction motor 12 is reduced. As a result, vibration is reduced.

In the first embodiment, the cycle T of the estimated average rotational speed is obtained from the frequency analysis of the estimated speed. However, the estimated slip frequency and the estimated motor torque also include the same pulsating component as the estimated speed. Therefore, these may be used instead of the estimated speed. The phase timing for giving the additional torque current command value is preferably as shown in FIG.
It is preferable to synchronize with the phase of the compression torque fluctuation. this is,
For example, this can be realized by adding an additional torque current command value in synchronization with a change in the estimated speed. However, even if it is added at a timing with a slightly different phase, there may be a state where the vibration increases transiently,
It has been experimentally confirmed that if the one-period pattern matches, the compression torque and the motor torque converge to a state in which the compression torque and the motor torque are almost equal to each other, as after the addition of the additional torque current command value shown in FIG.

Since the change in the estimated slip frequency and the change in the estimated motor torque include the same pulsating component as the estimated speed, the change in the estimated slip frequency and the estimated motor torque are included in the determination of the phase timing. The same operation can be realized by using the change. Furthermore, a change in the ambient temperature or the like causes a change in the shaft frictional resistance, for example, and as a result, the amplitude of the one-period pattern may deviate from the optimum value. Therefore, the difference between the compression torque and the motor torque is changed by changing the amplitude of the one-period pattern so that the fluctuation width of the estimated speed based on the change of the external environment becomes equal to or less than a predetermined value (for example, 5% of the estimated speed). Can be reduced. In order to avoid a transient increase in vibration due to this change, the change may be changed at a predetermined change rate (for example, an increase or decrease of 1% / sec of the amplitude). In this embodiment, the amplitude of the one-period pattern is changed so that the fluctuation width of the estimated speed becomes equal to or smaller than a predetermined value. 5% of the magnetic flux)
Since it has been confirmed that the same can be obtained even in the following case, the fluctuation width of the magnitude of the estimated secondary magnetic flux can be used instead of the fluctuation width of the estimated speed.

Further, the average torque current command value is maintained in a section from the first change of the amplitude of the one-cycle pattern of the additional torque current command value until it is determined, and thereafter until a predetermined period (5 to 10 cycles) has passed. It is desirable to hold the value before the change. This is performed in order to avoid deterioration in controllability due to a change in the estimated speed that occurs during the change of the additional torque current command value.

According to the first embodiment as described above, even if there is no accurate rotational position information of the three-phase induction motor, if there is information on the average rotational speed, the compression torque and the motor torque can be obtained even at the low frequency operation. Can be realized, and as a result, an effect of reducing vibration can be obtained. In the above description, the speed estimator is used, but it goes without saying that the same can be implemented by using a speed detector.

Second Embodiment In the first embodiment, the average torque current command unit 32 gives the average torque current command value based on the command speed and the estimated speed. However, the correspondence between the rotational speed and the compression load fluctuation pattern is known. Then, one cycle pattern of the additional torque current command value can be determined only by the command speed. The sum of the estimated speed ωme ^ and the calculated slip frequency ωs is
Instead of using the primary frequency ω0, if the sum of the command speed ωme * and the calculated slip frequency ωs is used as the primary frequency ω0,
Even when the estimated speed ωme ^ of the three-phase induction motor is disturbed, the primary current command value can be output without being affected by the disturbance, and the control device becomes more stable. The control system of the induction motor for a compressor according to the second embodiment realizes this method. This embodiment will be described below.

FIG. 4 is a block diagram showing a configuration of a control device for an induction motor for a compressor according to a second embodiment of the present invention. The command speed generator 1 outputs a command speed ωme * of the rotation speed of the three-phase induction motor 12 that drives the compressor 13. The exciting current command device 2 outputs a predetermined exciting current command value _{I1d *} . The torque current command device 3 'is provided with an additional torque current command device 31'.
And an average torque current commander 32 'and an adder 33'
It is composed of The average torque current command device 32 'in the torque current command device 3' outputs an average torque current command value corresponding to the command speed command value ωme *. On the other hand, the command speed ωme * and the estimated speed ωm
e ^ is input and the additional torque current command value is output. The operation of the additional torque current commander 31 'is the same as that described in the first embodiment. The average torque current command value and the additional torque current command value are added by an adder 33 ', and output from the torque current command device 3' as a torque current command value _{I1q *} .

The slip frequency calculator 4 calculates and outputs the slip frequency ωs using the exciting current command value I _{1d *} , the torque current command value I _{1q *,} and the electrical constant of the three-phase induction motor. The estimated speed ωme ^ and the slip frequency ωs are added by the adder 5 to become the primary frequency ω0. Further, the primary frequency ω0 is integrated by the integrator 6 to become a phase command value θ. Excitation current command value I _{1d *} , torque current command value I _{1q *} , phase command value θ
Is input to the primary current command device 7. The primary current command device 7 includes a rotating / stationary coordinate converter 71 and a two-phase / three-phase converter 72 connected to each other. Is converted to a two-phase AC current command value, and further converted to a three-phase AC current command value by the two-phase / three-phase converter 72. In the current controller 8,
The command value to the power converter 10 is controlled so that the motor current detected by the current detector groups 9a to 9c follows the primary current command value output from the primary current command device 7.
The converter 11 converts AC into DC to convert the power
To supply. Then, according to the command value of the current controller 8, the power converter 10 supplies a voltage to the three-phase induction motor 12 to flow a current. On the other hand, the speed estimator 14 estimates the rotational speed of the three-phase induction motor 12 using at least one of the primary AC current group and the primary AC voltage group of the three-phase induction motor 12 and the electric constant of the induction motor. .

Also in the second embodiment, the rotational speed information of the three-phase induction motor 12 is obtained, and an additional torque current command value for compensating for the excess or deficiency of the motor torque with respect to the compression torque fluctuation is output from the additional torque current command device 31 '. As a result, the difference between the compression torque and the motor torque is eliminated, and the rotation speed fluctuation is reduced. As a result, vibration can be reduced. The difference from the first embodiment is that the average torque current command device 32 'is a converter of the command speed / average torque current command value, and the primary frequency ω0 of the primary current command value is the speed command value ωme * and the slip frequency. ωs. The command speed / average torque current command value conversion map used in the conversion by the average torque current command device 32 ′ is a map of the average torque current command value required to obtain the average value of the compression torque at the speed command value and the compressor. We have in advance for the combination of three-phase induction motors. Using this map, Example 1
It is possible to perform almost the same operation as the average torque current commander 32 shown by. Moreover, even if the estimated speed is disturbed, the average torque current command value and the primary frequency are also constant calculated values, so that stable control can be performed.

As described above, according to the control device for an induction motor for a compressor according to the second embodiment, even if there is no accurate rotational position information of the three-phase induction motor, if there is information on the average rotational speed, a low Even during the frequency operation, the difference between the compression torque and the motor torque can be reduced. As a result, the effect of reducing vibration can be obtained. In the second embodiment, the torque current command device 3 ′ is constituted by the average torque current command device 31 ′, the additional torque current command device 32 ′, and the adder 33 ′. It may be. That is, a map of one cycle pattern for the command speed ωme * is prepared in advance as a combination of the average torque current and the additional torque current. In this case, the same operation can be realized.

[0038]

As described above, according to the present invention, even when accurate rotational position information of the induction motor cannot be obtained, if there is information on the average rotation speed, the rotation speed of the induction motor is low. However, the difference between the compression torque and the motor torque can be reduced with good responsiveness. Therefore, it is possible to reduce the fluctuation of the rotation speed of the induction motor, and as a result, it is possible to reduce the level of vibration even at the time of low-frequency operation, which has been a problem in a compressor that generates vibration synchronized with rotation in the related art. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control device for an induction motor for a compressor according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of an additional torque current commander of the control device for the induction motor for the compressor according to the first embodiment of the present invention.

FIG. 3 is a diagram showing waveforms depending on the presence or absence of an additional torque current.

FIG. 4 is a block diagram illustrating a configuration of a control device for an induction motor for a compressor according to a second embodiment of the present invention.

FIG. 5 is a diagram showing waveforms of a compression torque and a motor torque in a conventional induction motor for a compressor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 command speed generator 2 excitation current commander 3, 3 ′ torque current commander 4 slip frequency calculator 5 adder 6 integrator 7 primary AC current commander 8 current controller 9 a to 9 c current detector 10 power converter 11 Converter 12 Three-phase induction motor 13 Compressor 14 Speed estimator 31, 31 'Additional torque current commander 32, 32' Average torque current commander 33 Adder 71 Rotary / stationary coordinate converter 72 Two-phase / three-phase converter

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yoshiaki Igarashi 1006 Kadoma, Kadoma, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. FF07 GG02 GG04 HB01 JJ03 JJ04 JJ05 JJ22 JJ24 LL14 LL15 LL22 LL30 LL34 LL38

Claims (19)

[Claims] 1. A compressor for compressing a refrigerant that generates a pulsating torque synchronized with rotation, a three-phase induction motor driving the compressor, and a frequency of an actual rotation cycle of the three-phase induction motor. A speed estimator that estimates the speed of rotation and outputs an estimated speed, and a torque current commander that outputs a torque current command value that is a torque current component of a primary AC current group supplied to a stator of the three-phase induction motor. An exciting current commander that outputs an exciting current command value that is an exciting current component of the primary AC current group; and a slip that calculates a slip frequency of the three-phase induction motor from the torque current command value and the exciting current command value. A frequency calculator, a primary AC current commander that outputs a primary AC current command value according to the torque current command value, the exciting current command value, the estimated speed, and the slip frequency; A current detector group for detecting each current of the primary AC current group, and controlling the primary AC current group based on each output of the current detector group so as to match the corresponding primary AC current command value. And a power converter for supplying the primary AC voltage group to a stator of the three-phase induction motor according to an output of the current controller. However, the torque current commander is an average torque current command value calculated according to the command speed of the three-phase induction motor and the estimated speed, and an additional torque having the same cycle as the rotation cycle of the estimated speed. A control device for an induction motor for a compressor, which outputs a sum with a current command value as the torque current component command value. 2. A compressor for compressing a refrigerant that generates a pulsating torque synchronized with rotation, a three-phase induction motor driving the compressor, and a frequency of an actual rotation cycle of the three-phase induction motor. A speed detector that detects the speed of rotation, a torque current command device that outputs a torque current command value that is a torque current component of a primary AC current group supplied to the stator of the three-phase induction motor, and the primary AC current group An exciting current commander that outputs an exciting current command value that is an exciting current component of: a slip frequency calculator that calculates a slip frequency of the three-phase induction motor from the torque current command value and the exciting current command value; A primary AC current commander that outputs a primary AC current command value according to the torque current command, the exciting current command, the output of the speed detector, and the slip frequency; and the primary AC current. And a current controller for controlling the primary AC current group based on each output of the current detector group so as to match the corresponding primary AC current command value. And a power converter that supplies a primary AC voltage group to a stator of the three-phase induction motor in accordance with an output of the current controller. The current command device is a command speed value of the three-phase induction motor, an average torque current command value calculated according to the output of the speed detector, and the three-phase time-averaged output of the speed detector. A control device for an induction motor for a compressor, wherein a sum of an average rotation period of the induction motor and an additional torque current command value having the same cycle is output as the torque current command value. 3. A compressor for compressing a refrigerant that generates a pulsating torque synchronized with rotation, a three-phase induction motor driving the compressor, and a rotation speed represented by a frequency of a rotation cycle of the three-phase induction motor. And a torque estimator that outputs a torque current command value that is a torque current component of a primary AC current group supplied to a stator of the three-phase induction motor. An exciting current commander that outputs an exciting current command value that is an exciting current component of an alternating current group; a slip frequency calculator that calculates a slip frequency of the three-phase induction motor from the torque current command value and the exciting current command value. A primary AC current command for outputting a primary AC current command value according to the torque current command value, the exciting current command value, the speed command value of the three-phase induction motor, and the slip frequency. And a current detector group for detecting the current of each of the primary AC current groups, and the primary AC current so that the output of the current detector group matches the corresponding primary AC current command value. A control device for an induction motor for a compressor, comprising: a current controller that controls a group; and a power converter that supplies the primary AC voltage group to a stator of the three-phase induction motor according to an output of the current controller. An average torque current command value that is predetermined according to a command speed of the three-phase induction motor, and an additional torque current command value having the same cycle as the rotation cycle of the estimated speed. And a control device for the induction motor for the compressor. 4. A compressor for compressing a refrigerant that generates a pulsating torque synchronized with rotation, a three-phase induction motor driving the compressor, and a frequency of an actual rotation cycle of the three-phase induction motor. A speed estimator for estimating a rotation speed and outputting an estimated speed; and a torque current command for outputting a torque current command value which is a command of a torque current component of a primary alternating current group supplied to a stator of the three-phase induction motor. An exciting current commander that outputs an exciting current command value that is an exciting current component of the primary AC current group; and calculates a slip frequency of the three-phase induction motor from the torque current command value and the exciting current command value. A slip frequency calculator that outputs a primary AC current command value according to the torque current command value, the exciting current command value, the speed command value of the three-phase induction motor, and the slip frequency. A secondary AC current commander, and a current detector group for detecting the current of each of the primary AC current groups, such that the output of the current detector group matches the corresponding primary AC current command value, A current controller that controls the primary AC current group; and a power converter that supplies the primary AC voltage group to a stator of the three-phase induction motor in accordance with an output of the current controller. A control device for an induction motor for a compressor, wherein the torque current command device outputs the torque current command value having a cycle pattern having the same cycle as the rotation cycle of the estimated speed. . 5. The torque current commander generates an additional torque current command value having the same cycle as the rotation cycle of the estimated speed of the three-phase induction motor when the frequency of the primary AC current command value is smaller than a predetermined value. The control device for an induction motor for a compressor according to claim 1 or 3, wherein: 6. The torque current commander generates an additional torque current command value having the same cycle as the rotation cycle of the detection speed of the three-phase induction motor when the frequency of the primary AC current command value is smaller than a predetermined value. The control device for an induction motor for a compressor according to claim 2, characterized in that: 7. The torque current commander generates a torque current command value having the same cycle as the rotation cycle of the estimated speed of the three-phase induction motor when the frequency of the primary AC current command value is smaller than a predetermined value. The control device for an induction motor for a compressor according to claim 4, wherein 8. A speed estimator comprising: an estimated speed and an estimated slip frequency calculated using at least one of a primary AC current group and a primary AC voltage group of a three-phase induction motor and an electrical constant of the three-phase induction motor. 5. The control device for an induction motor for a compressor according to claim 1, wherein the controller outputs an estimated speed based on a frequency of a pulsating component of the estimated torque. 6. 9. The torque current commander includes an estimated speed and an estimated slip calculated using at least one of a primary AC current group and a primary AC voltage group of a three-phase induction motor and an electrical constant of the three-phase induction motor. 4. The control device for an induction motor for a compressor according to claim 1, wherein a phase timing for giving a periodic pattern of the additional torque current is determined according to a change in either the frequency or the estimated torque. 10. A torque current commander according to a change in a detection speed of a three-phase induction motor output from a speed detector.
The control device for an induction motor for a compressor according to claim 2, wherein a phase timing for giving a periodic pattern of the additional torque current is determined. 11. The torque current commander includes at least one of a primary AC current group and a primary AC voltage group of a three-phase induction motor.
A phase timing that gives a periodic pattern of torque current is determined according to a change in any of the estimated speed, estimated slip frequency, or estimated torque calculated using the electrical constants of the three-phase induction motor and the three-phase induction motor. The control device for an induction motor for a compressor according to claim 4, wherein 12. The torque current commander includes at least one of a primary AC current group and a primary AC voltage group of a three-phase induction motor.
And the cycle of the additional torque current so that the fluctuation width of any of the estimated speed, the estimated torque, or the magnitude of the secondary magnetic flux calculated using the electrical constants of the three-phase induction motor and the magnitude of the secondary magnetic flux is equal to or less than a predetermined value. 4. The control device for an induction motor for a compressor according to claim 1, wherein the amplitude of the pattern is changed. 13. The torque current commander changes an amplitude of a cycle pattern of an additional torque current so that a fluctuation width of a detection speed of the three-phase induction motor output from the speed detector becomes equal to or smaller than a predetermined value. The control device for an induction motor for a compressor according to claim 2, characterized in that: 14. A torque current commander includes at least one of a primary AC current group and a primary AC voltage group of a three-phase induction motor.
And the periodic pattern of the torque current so that the fluctuation width of any of the estimated speed, the estimated torque, or the magnitude of the secondary magnetic flux calculated using the electric constants of the three-phase induction motor and the magnitude of the secondary magnetic flux is equal to or less than a predetermined value. 5. The control device for an induction motor for a compressor according to claim 4, wherein the amplitude of the induction motor is changed. 15. The torque current commander changes at least one of the primary AC current group and the primary AC voltage group of the three-phase induction motor while changing the amplitude of the periodic pattern of the additional torque current at a predetermined rate or less. The periodic pattern of the additional torque current so that the variation width of any of the estimated speed, the estimated torque, or the magnitude of the secondary magnetic flux calculated using the electrical constants of the phase induction motor is equal to or less than a predetermined value. 4. The control device for an induction motor for a compressor according to claim 1, wherein the amplitude of the induction motor is changed. 16. The torque current commander changes the amplitude of the periodic pattern of the additional torque current at a predetermined rate or less while controlling the fluctuation width of the detection speed of the three-phase induction motor output from the speed detector to a predetermined value. The control device for an induction motor for a compressor according to claim 2, wherein the amplitude of the periodic pattern of the additional torque current is changed so as to be equal to or less than a value. 17. The torque current commander is configured to change at least one of a primary AC current group and a primary AC voltage group of a three-phase induction motor while changing the amplitude of the periodic pattern of the torque current at a predetermined rate or less. The amplitude of the periodic pattern of the torque current, such that the fluctuation width of any of the estimated speed, the estimated torque, or the magnitude of the secondary magnetic flux calculated using the electric constant of the induction motor is equal to or less than a predetermined value. The control device for an induction motor for a compressor according to claim 4, wherein 18. The torque current commander, after starting to change the amplitude of the periodic pattern of the additional torque current at a predetermined rate or less, sets at least one of a primary AC current group and a primary AC voltage group of the three-phase induction motor. The cycle of the additional torque current is adjusted so that the variation width of any of the estimated speed, the estimated torque, or the magnitude of the secondary magnetic flux calculated using the electrical constants of the three-phase induction motor is equal to or less than a predetermined value. After changing the amplitude of the pattern, the average torque current command keeps the value before starting to change the amplitude of the periodic pattern of the additional torque current at a predetermined rate or less until a predetermined period elapses. The control device for an induction motor for a compressor according to claim 1 or 3, wherein: 19. The torque current commander, after starting to change the amplitude of the periodic pattern of the additional torque current at a predetermined rate of change or less, sets the fluctuation range of the detection speed of the three-phase induction motor output from the speed detector to a predetermined value. After changing the amplitude of the cycle pattern of the additional torque current so as to be equal to or less than the value, the average torque current command value changes the amplitude of the cycle pattern of the additional torque current by a predetermined rate until a predetermined period elapses. 3. The control device for an induction motor for a compressor according to claim 2, wherein a value before the change is started is kept below.