JPH03203592A - Controlling system of induction motor for compressor - Google Patents

Abstract

PURPOSE:To permit necessary torque and generation turque to coincide with each other by feeding the AC power of a pattern set according to the angle of rotation of a compression element, to an induction motor, every time the angle of rotation of the compression element comes to a specified angle. CONSTITUTION:The position of a rotor connected directly to a compression element is detected by a Hall element 24, and the input to a control section 31 via a position detection circuit 30 is provided. In the control section 31, the AC power of a pattern necessary according to the angle of rotation of the compression element, namely, a switching pattern to be applied to switching elements 32-37 is stored, and according to the output of a speed command circuit 40 and the position detection circuit 30, by the pattern, the switching of the switching elements 32-37 is performed via a base drive circuit 38.

Description

[Detailed Description of the Invention] Kui〉Field of Industrial Application The present invention relates to a compressor in which an induction motor and a compression element rotationally driven by the rotor of the induction motor are housed in the same case. The present invention provides a control method that reduces the vibration and noise of the compressor by controlling the drive torque of the induction motor.

(b) Conventional technology As a control system for such a compressor, Japanese Patent Application Laid-open No. 60-6
There was something like the one described in Publication No. 0286.

The motor described in this publication is designed to output motor output torque in synchronization with changes in load torque applied during one rotation of an electric element that drives a compression element of a compressor. That is, the load torque is constantly detected during one rotation of the motor, and the output of the motor is changed to match the load torque.

(c) Problems to be Solved by the Invention In the control system for the compressor configured in this way, it is necessary to constantly detect the rotational position of the compressor, and a large number of position detectors are required. There were problems such as the need for high accuracy in the process, and the need to calculate and output the output of the motor sequentially, making the control circuit complex.

In order to solve these problems, the present invention provides a control method that makes it possible to control the torque of an induction motor using simple position detection and a simple control method.

(d) Means for Solving the Problems The present invention provides a compressor in which an induction motor and a compression element rotationally driven by the rotor of the induction motor are housed in the same case. AC power in a pattern determined corresponding to the angle is supplied to the induction motor in order from a specific phase position of the AC power every time the rotation angle of the compression element reaches a predetermined angle. .

In addition, the pattern is such that the driving torque required by the compression element is increased by increasing the voltage or current of the AC power supplied to the induction motor, and the pattern is formed by increasing the voltage or current of the AC power supplied to the induction motor. It is set to change continuously.

In addition, the pattern is made up of AC power supplied to the rotation angle at which the driving torque required by the compression element becomes large, and the frequency of the AC power supplied to the induction motor is greater than the frequency of one period of the pattern. The frequency is set so that the change in frequency during one period is continuous.

(*〉Operation) Using the control method configured in this way, the compression element of the compressor generates AC power in a pattern in which the output to the induction motor changes in accordance with fluctuations in the load torque that changes during one rotation. It is something that can be obtained.

(F> Example) Hereinafter, an example of the present invention will be explained based on the drawings. Fig. 1 is a sectional view of a compressor. In this figure, 1 is a closed container, inside which a compression element 4 and a three-phase induction The three-phase induction motor 3 includes a stator 5 around which three-phase windings are wound, and a rotor 6 that is rotated by a magnetic field generated from the stator 5.
It consists of. A compression element 4 is connected to the shaft 13 of this rotor. The compression element 4 includes a crank part 14 that rotates using the shaft 13 as the crankshaft 2, and a roller 8 that rotates within the cylinder 7 by the crank part 14.
, an upper bearing portion 10 and a lower bearing portion 11 that close the opening of the cylinder 7, and a cup muffler 1 attached to the upper bearing portion.
It is composed of 2. A vane 9 is in contact with the roller 8 and divides the inside of the cylinder 7 into a high pressure chamber and a low pressure chamber. Reference numerals 16 and 17 denote balancers, which are provided to be dynamically or statically balanced with the crank portion 14 of the crankshaft 2. 18 is a discharge pipe, which is attached to the earthen wall of the closed container 1.

FIG. 2 is a 1-1 sectional view of the compressor shown in FIG. 1.

In this figure, 19 is a discharge port, 20 is a suction port, and sections 21 and 22 in the cylinder 7 are a high pressure chamber and a suction port, respectively.
It is a low pressure chamber. Further, the roller 8 rotates in the direction of the solid line arrow in FIG. 2, and the contact point position where the roller 8 contacts the cylinder 7 is shown as a rotation angle of 360 degrees. In the state shown in FIG. 2, the rotational position of the roller 8, that is, the crankshaft 2 (shaft 13) is 180 degrees.

FIG. 3 is a sectional view of a main part showing a state in which a position detector for detecting the rotational position of the compression element 4 is attached to the compressor shown in FIG. 1. The compression element 4 is connected to the crankshaft 2 (rotor 6
Since the rotor 6 rotates simultaneously through the shaft 13) of the rotor 6, in reality, if the rotation angle of the rotor 6 is detected, the compression element 4
The 0-position detector capable of detecting the rotation angle of the sensor is made up of a magnet 23 and a magnetic detector (Hall element) 24 bonded to a disc-shaped disk 22. disk 22
is attached to the shaft 13 by bolts 25 so that the center of rotation coincides with the shaft. The positional relationship between the magnet 23 and the Hall element 24 is such that the Hall element 24 detects magnetism and changes its output when the rotation angle shown in FIG. 2 is '0' degree. Therefore, an output can be obtained every time the crank portion (rotor) of the compression element 4 rotates by 0 degrees. The Hall element 24 is the airtight container 1 of the compressor.
A bottomed pipe 27 is inserted from the side of the discharge pipe 18 and provided at the bottom of this pipe 27.

Further, this pipe 27 is welded to the closed container 1 to prevent the high pressure gas inside the compressor from leaking. Furthermore, 2
A balancer 6 corrects the weight balance caused by attaching the Hall element 24.

FIG. 4 is a control circuit diagram for controlling the operation of the compressor shown in FIGS. 1 to 3. FIG. In this figure, 27 to 29 are stator windings of the induction motor 5, which are star-connected.

By applying three-phase alternating current to the stator windings 27 to 29, the magnet 23 attached to the disk 22 of the rotor 5 rotates. Therefore, the output of the Hall element 24 changes with the rotation of the rotor 5 (compression element), and the position detection circuit 30 converts this change into a signal and outputs it to the control section 31. 3
2 to 374-1 is a switching element that operates ON10FF, and is connected in a three-phase bridge shape, and converts the DC power supplied from the DC power supply 39 to the three-phase stator windings 27 to 29 into three-phase AC power. Convert and output. These switching elements (transistor elements, FET elements, GT
Diodes are connected to the semiconductor switching elements (such as O elements) 32 to 37, respectively, for discharging accumulated charges and forming a circulating circuit for circulating current generated in the stator windings 27 to 29. The DC power source 39 may be rectified and smoothed AC power or DC power from a battery. Moreover, the switching elements 32 to 37 are 0N10
The FF operation is controlled by the control section 31 via the base drive circuit 38.
controlled by signals from This control section is mainly composed of a CPU, RAM, ROM, I10 interface, etc., and calculates a frequency based on the speed signal from the speed command circuit 40, and supplies AC power at this frequency to the stator windings 27 to 29. The switching elements 32~
Controls the 0N10FF operation of 37.

The switching signals applied to the switching elements 32 to 37 will be explained below. FIG. 5 is an explanatory diagram for obtaining switching signals based on PWM theory. In this figure, ``, 50, 51, and 52 are sine waves, each with 1
The phase shift is shifted by 200. 53 is a triangular wave, and the output obtained by comparing the magnitudes of these sin waves 50 to 52 and the triangular wave 53 is the switching signal of the switching elements 32, 34, and 36. Note that the switching signal of switching element 33°35.37 is the same as that of switching element 32.
, 34 and 36 are inverted. By using these six types of switching signals, the stator windings 27 to 2 of the induction motor
8 can be supplied with three-phase AC power having the same frequency as the sine waves 50 to 52. Therefore, these si
When the frequency of n-waves 50 to 52 is changed, stator windings 27 to 52
The frequency of the AC power supplied to 29 can be changed. Furthermore, by changing the ratio of the amplitudes of the sine waves 50 to 52 and the triangular wave 53, the alternating current voltage (voltage when replaced with a sine wave) supplied to the stator windings 27 to 29 can be changed. Incidentally, the same implementation can be performed using a switching signal based on PAM theory.

The switching patterns of the switching elements 32 to 37 obtained in this way (0N10FF of the switching elements
) is stored in the ROM of the control unit 31. The CPU sequentially reads out the 0N10FF signals of this pattern and outputs them to the switching elements 32-37. As for the storage format in this ROM, the entire pattern or a part of the pattern may be stored and combined at the time of reading. Furthermore, the pattern may be separated and stored into a time for outputting an ON signal and a time for outputting an OFF signal, or a pattern for one period may be broken down for each predetermined phase angle, and further ON within the predetermined angle may be stored. time and o
It is also possible to separate the data into FF times and store them.

Alternatively, the switching signal of the switching element may be obtained by calculating from the magnitude of the sine wave and the triangular wave at the specified phase angle. At this time, a switching signal for one cycle is obtained by changing the specified phase angle from 0° to 360°.

FIG. 6 is a diagram of three-phase AC voltage waveforms (equivalently replaced with sine waves) 61-63 obtained by 0N10FF of switching elements 32-37. The respective voltage waveforms are 120 degrees out of phase. In this control method, this output voltage is not simply supplied to the stator windings 27 to 28, but is synchronized with the signal from the position detector every time the rotation angle of the crank part of the compression element reaches 0°. Oo shown in Figure 6
The voltage supply to the stator windings 27 to 29 is started from the phase angle position of . Note that the slip of the electric motor will be omitted in the following explanation. Therefore, when the rotation angle of the compression element is Oo, the voltage supplied to the stator winding is always the voltage when the phase angle is 0° as shown in FIG. 67 is a waveform showing the relationship between the driving torque required when the compression element is driven. As described above, there is a torque fluctuation during one rotation of the compression element, and this torque fluctuation causes vibration of the compressor. Therefore,
The output of the induction motor is increased to match this drive torque. For example, if the rotation angle of the crank part that requires a large torque during one rotation of the compression element is limited to around 200° (in the case of one cylinder), when the crank part is at a rotation angle around this The voltage applied to the child winding may be made higher than usual. The rotation angle of the crank unit 0° and the phase angle of the voltage pattern 0° are matched by the output of the position detector, and the rotation angle of the crank unit and the phase angle of the voltage pattern supplied to the stator windings match. (Ignore the slip of the induction motor) Therefore, the voltage waveform 6 shown in Figure 6
If the voltage around 200 degrees of the phase angles 1 to 63 is made higher than usual, this torque fluctuation can be coped with.

The voltage waveforms shown at 64 to 66 in FIG. 6 take this torque fluctuation into consideration. That is, these voltage waveforms 64 to 66
When the phase angle is around 200°, the voltage and frequency (the frequency in one cycle of this pattern, that is, the angular velocity of the phase) are increased to increase the output torque of the motor, and when the phase angle is around 0°, the output torque of the motor is increased.
The output torque of the motor is reduced by reducing the voltage and frequency in the vicinity. The voltage and frequency of the voltage pattern are set so that the output of the motor changes continuously between a phase angle where the output of the motor increases and a phase angle where it decreases. Note that 68 and 69 are examples of waveforms used for voltage correction and waveforms used for frequency correction, respectively. Voltage waveforms 64 to 66 are obtained by multiplying the three-phase AC waveforms 61 to 63 by a correction value such as waveform 68.69.

Therefore, as described above, data for obtaining switching signals such that these voltage waveforms 64 to 66 are supplied to the stator windings 27 to 29 is stored in the ROM of the control unit 31. Actually, the amplitude of the voltage waveforms 64 to 66 is set in accordance with the change in the actual driving torque of the compression element, since the amplitude of the voltage waveform is further changed depending on the frequency.

By supplying the switching signals obtained in this way to the switching elements 32 to 37, when the compression element requires a large torque, the output of the induction motor is increased to increase the torque and suppress the vibration of the compressor. Can be suppressed.

Furthermore, the switching signals for obtaining the voltage waveforms 61 to 63 shown in FIG. 6 are calculated once the phase Ph from which the frequency f1 output voltage v1 switching signal is desired is determined. Note that f is equal to the frequency signal given from the speed command circuit, and the basic value of ■ is determined based on the value of f so that V/r = constant value, and this constant value is the same as the induction motor, i.e. The operating efficiency of the compressor is set to improve at each frequency. Ph value from 0 to 360°
A switching signal for obtaining one period's worth of AC power is output by changing the AC power to . In reality, the value of Ph is advanced by APh, and the same switching signal is maintained between and Δph. Advancement amount ΔPh of this Ph
If this value is increased, the resolution in one cycle will deteriorate, and if this value is decreased, the resolution will be improved, but the optimal value of ΔPh for each frequency is is set in advance.

FIG. 7 is a vibration waveform chart showing the actual vibration state of the compressor. This vibration waveform 71 is measured at the outer circumference of the compressor (first
Attach an acceleration sensor near the top of stator 5 in the figure),
This is obtained from the output of this sensor. The angle in this figure corresponds to the rotational position of the crank portion 14 shown in FIG. As can be seen from this figure, the crank part 1 of the compression element
4, the amplitude of vibration becomes large between 130° and 270°. Note that this section coincides with the compression process in the compression element.

This vibration waveform 73 is obtained when AC power obtained using a voltage waveform as shown in the stator winding 73 of the compressor is supplied. Note that the other phases among the three phases are omitted because they are only different in phase. This voltage waveform 73 can be expressed by the following equation.

V = V, sin θ (1) Therefore, equation (1) should be corrected so that the driving torque becomes large between 1300° and 270°.

That is, the amplitude of equation (1) in this section is increased to increase the driving torque.

In the following embodiment, this correction is performed by approximating a sine wave. The section where an increase in driving torque is required is 130
Since it is between 270° and 270°, the center of this section, i.e. 2
A sine wave with a peak at 00° 7 wave lines 2 is constant.

Same period (frequency) as this sine wave 7 wavy line 2in wave 73
and its function is V=Asin(θ+11o')--
---It can be expressed as (2). A is sine wave 53
is the amplitude of Therefore, the sine wave for obtaining the driving torque required by the compression element is the sum of equation (1> and equation (2)), and is expressed by the following equation (3>).

V = (V, sin θ) + (A sin (θ + 110
°)〉=V*(1+A/V*)(sinθ+5in(θ
+110°)> (3) The value of A/V is arbitrarily selected from 0.05 to 0.2 depending on the frequency applied to the induction motor.

If a switching signal is obtained from the sine wave according to equation (3) and the triangular wave shown in FIG. 5, a large driving torque can be obtained during the compression process of the compression element.

At this time, the voltage (effective voltage after converting into a sine wave) applied to the induction motor changes during one rotation of the compressor. Therefore, the above-mentioned rV/f'=- can be achieved by changing the value of f, and the value of f, that is, the frequency, is changed during one rotation of the compressor in accordance with the change in voltage. Similar to the voltage correction, this frequency change is also corrected so that the correction peak occurs when the angle is 200°. At this time, the correction on the plus side is made larger than the correction on the minus side.

In this example, the correction was performed by approximating a sine wave, but the invention is not limited to this. For example, an approximation formula such as a (sin)" wave (used in place of formula <1> in this case) is applied to the torque characteristics of the compression element. You can set them accordingly.

FIG. 8 is a broachate (output frequency is fixed) showing the operation when correction is made using the above equation (3>).

First, in step S1, it is determined whether there is a 0° signal. That is, the rotation angle of the compression element becomes 0°, and the position detector 2
It is determined whether there is a signal from 4. If there is a signal, the process proceeds to step S2 where θ=0 to match the rotation angle of the compression element of 0° and the phase angle of the output voltage pattern of 0°. Further, if there is no signal in step S1, the process advances to step S3. In this step S3, the value of θ is advanced by Δθ. If the value of Δθ is made small, the resolution of the output voltage to the stator winding will be improved, but on the other hand, if it is made too small, the switching speed of the switching element will not be able to keep up with the switching speed, resulting in an uncontrollable problem. In this embodiment, for example, Δθ=
Set to 1. However, this is not the case if the switching speed of the switching element can catch up. After this, the process advances to step S4.

demand. At this time, the value of θ is further corrected according to θ. That is, the phase angle is advanced and the angular velocity (frequency) around this phase angle is increased or decreased. Next, the process proceeds to step S5, and the ON10 FF signal of the switching element is obtained from the sin value and the triangular wave value obtained in step S4. In step S6, this 0N10FF signal is maintained for a predetermined time. This maintenance time X360 (from Δθ=1) is 1
The period time is the frequency of the AC power supplied to the induction motor. Therefore, if the frequency (time of one cycle) is determined, the maintenance time is determined.

In addition, in this flowchart, 0N10F is set for each cycle.
Although the F signal has been calculated, this signal is calculated in advance, and the data that allows this calculated signal to be obtained is stored in the ROM.
It is also possible to continuously output one cycle in accordance with the 0° signal.

FIG. 9 is a vibration waveform diagram showing changes in the vibration waveform when torque control is performed according to the flowchart. (Measurement of vibration is the same as in Figure 7) In this figure, the section without torque control is the output calculated using the waveform diagram 61 in Figure 6 when the induction motor is habituated; In the section, the output calculated using the waveform diagram 64 in FIG. 6 is supplied to the induction motor. As can be seen from this figure, vibration is smaller when torque control is performed. It should be noted that since the control was switched between the presence and absence of control while the compressor was in operation, a transient period occurred until the vibration became smaller.

(G) Effects of the Invention As described above, the present invention provides a compressor having an induction motor, in which AC power is applied in a predetermined pattern corresponding to the rotation angle of the compression element until the rotation angle of the compression element is at a predetermined angle. Each time the alternating current power reaches the induction motor, the alternating current power is supplied to the induction motor in order from a specific phase position, and the pattern is such that the driving torque required by the compression element is increased by increasing the voltage or current of the alternating current power supplied to the induction motor. Therefore, it is possible to match the output of the induction motor in accordance with an increase in the driving torque of the compressor, thereby reducing vibrations caused by the difference between the torque and the output.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a compressor using the control method of the present invention, FIG. 2 is a cross-sectional view of the compressor shown in FIG. 1, and FIG. 3 is a sectional view of the compressor shown in FIG. 4 is a control circuit diagram of the compressor shown in FIG. 1, FIG. 5 is an explanatory diagram showing the 0N10FF signal of the switching element, and FIG. 6 is the switching element. ON10F
Fig. 7 is a vibration waveform diagram obtained by measuring the actual vibration state of the compressor, Fig. 8 is a flowchart showing the generation of the 0N10FF signal, and Fig. 9 is the control of the present invention. FIG. 4 is a vibration waveform diagram when using the method. DESCRIPTION OF SYMBOLS 1... Compressor, 3... Induction motor, 4... Compression element, 6... Rotor, 23... Magnet, 24... Hall element, 27-29... Stator winding Line, 31...Control unit, 32-37...
switching element. Figure 1 Figure 5 50 Figure 2 70 o°136206276J60 1811U Sl No. 91!1

Claims (5)

[Claims] (1) In a compressor in which an induction motor and a compression element rotationally driven by the rotor of the induction motor are housed in the same case, an alternating current of a pattern predetermined corresponding to the rotation angle of the compression element is used. A control method for an induction motor for a compressor, characterized in that power is supplied to the induction motor in order from a specific phase position of the AC power every time the rotation angle of the compression element reaches a predetermined angle. (2) The induction for a compressor according to claim 1, wherein the pattern is formed by increasing the voltage or current at a phase position corresponding to a rotation angle where the driving torque required by the compression element increases. Electric motor control method. (3) The induction motor for a compressor according to claim 2, wherein the pattern is set so that the voltage or current of the AC power supplied to the induction motor changes continuously. control method. (4) The pattern is characterized in that the frequency of the phase position corresponding to the rotation angle at which the driving torque required by the compression element increases is greater than the frequency of one period of the pattern. Control method for induction motor for compressor. (5) The pattern is one of AC power supplied to the induction motor.
5. The control method for an induction motor for a compressor according to claim 4, wherein the control method is set so that the frequency changes during a cycle are continuous.