KR910000097B1 - Motor-driven compressor provided with torque control device - Google Patents

Abstract

No content.

Description

Electric compressors with torque control

1 is an overall schematic diagram of Embodiment 1 of the present invention.

2 is a cross-sectional view taken along the line II-II of FIG.

3 is a control circuit diagram.

4 is a detailed view of a torque control circuit.

5 is a diagram illustrating a detection signal output from an electronic pickup.

6 is a view showing a variation in the rotational speed of the main shaft.

7, 8 and 9 are operation explanatory diagrams.

10 is a diagram showing a relationship between a load torque and an output torque.

11 shows torsional vibration characteristics with respect to rotational speed.

12 is a front view of main parts of the second embodiment;

13 is a front view of main parts of the third embodiment;

14 is a view showing response signals of the load detector and the strain detector used in Examples 2 and 3. FIG.

15 is a sectional view of principal parts of Example 4. FIG.

16 is a diagram showing the pressure variation of the compression chamber.

FIG. 17 is a view showing variation of load torque. FIG.

18 is a diagram in which load torque is developed as a feedwater to a pushey.

19 shows the relationship between the output torque and the load torque.

* Explanation of symbols for main parts of the drawings

1: case 2: electric motor

3: stator 7: rotor

10 compressor 11 spring

14 roller 16 aerator

19: gear 20: electronic pickup

23: rotation speed control circuit 25: torque control circuit

27: speed command circuit 30: comparator

31: temperature detector 33: fixing mechanism

35 support member 38 deformation detector

39: pressure sensor

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electric compressor used for compressing means of a refrigeration cycle such as an air conditioner, a domestic refrigerator, or a high pressure gas, and in particular, an electric compressor having a torque control device suitable for a type of varying driving rotation speed. It is about.

For example, as shown in US Pat. No. 4,373,356, it is known to attenuate vibration generated in a compressor by interposing a spring between the sealed container and the compressor or the motor when installing the motor and the compressor in the sealed container. In addition, it is known that the hermetic container, the electric motor, and the compressor are adhered to each other to support the hermetic container through a spring and to damp vibration as well.

The conventional one does not control the generation of vibration itself, and it is difficult to attenuate it to such an extent that it does not interfere with actual use of vibration as an elastic body such as a spring or rubber.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electric compressor having a torque control device which can be made small so as not to interfere with the actual use of vibration, especially torsional vibration in the rotational direction.

Another object of the present invention is to provide an electric compressor having a torque control device capable of substantially preventing torsional vibration.

Another object of the present invention is to control an electric compressor equipped with a torque control device capable of controlling the generation of the torsional vibration itself.

A feature of the present invention is that in a compressor driven by an electric motor coupled through a main shaft, the rotation angle of one rotation of the main shaft is divided into a plurality of ranges, and the angular velocity of the main shaft detected for each of these division ranges and the reference And a torque control device for obtaining a difference from the angular velocity, and controlling the output torque of the motor for each divided range according to the difference.

1 to 10 are explanatory views of Embodiment 1 of the present invention. 1, 2, 3 and 4 illustrate a rotary compressor in which the electric motor 2 and the compressor 10 are housed in the case 1. The electric motor 2 includes a stator 3 fixed to the case 1, a main shaft 6 supported by the main bearing 4 and an end bearing 5, and a rotor 7 fixed to the main shaft 6. Compressor 10 is a roller block which is interlocked with the cylinder block (12) fixed to the case (1) and the main shaft (6) and disposed in the cylinder block (12) to form a compression operation chamber (13). It consists of 14. Reference numeral 15 denotes a vane which protrudes in the compression operation chamber 13 and abuts on the surface of the roller 14, and is always in contact with the roller 14 by the force of the spring 11. Reference numeral 16 is a suction accumulator, and when the main shaft 6 rotates, the refrigerant gas is sucked from the accumulator 16 and pressurized to a predetermined pressure in the compression operation chamber 13, as shown by the arrow in FIG. In one direction, the roller case 1 is discharged to the condenser 8 in contact with the pipe case 17 via the pipe 17. The condenser 8 is brought into contact with the evaporator 18 via an expansion valve 9, and the outlet of the evaporator 18 is brought into contact with the suction agitator 16. The upper end of the main shaft 6 constituting the compressor 10 extends upwards, and the teeth 19 are fixed to this portion, and the teeth 19 are rotated integrally with the main shaft 6. The electronic pickup 20 having its own magnetic field is fixed to the case 1 opposite to the gear 19. The electronic pickup 20 outputs a signal corresponding to the rotational speed of the main shaft 6 as shown in FIG. That is, the time t until the signal crosses the reference line 32 after the signal crosses the reference line 32 with respect to the reference line indicated by reference numeral 32 in FIG. In this way, the rotational speed of the main shaft 6 at every instant is obtained from the number of teeth of the gear 19.

와 치차(19)의 치형수(m)에 의해 구할 수 있고, 빠름과 늦음의 양 w는

에 의해 구할 수 있다.FIG. 6 shows the variation of the rotational speed of the main shaft 6 based on the rotational speed signal shown in FIG. 5, showing that the area A is fast and the area B is slow. And the average rotational speed is the average time

Can be obtained by the number of teeth (m) of the gear 19 and the amount w of fast and late

Can be obtained by

The output side of the electronic pickup 20 is connected to the operational memory circuit 22 via the waveform shaping circuit 21. A rotation speed control circuit 23 is connected to the electric motor 2, and a base driver 24 (base driver) is connected to the rotation speed control circuit 23.

The torque control circuit 25 forms a chopper signal based on the rotation time required for each rotation angle range sent from the operation memory circuit 22 or the deviation signal of the angular velocity, and sends it to the base driver 24. It is.

The rotational speed control circuit 23 is a 120 ° energized inverter composed of transistors TR ₁ to TR ₆ and reflux diodes D ₁ to D ₆ , and its AC output voltage is positive (cross) of the DC voltage E _d . The conduction period of 120 ° of the potential transistors TR ₁ to TR ₆ is controlled by the chopper operation under pulse width modulation.

The low resistance R ₁ is connected between the common emitter terminals of the transistors TR _{1 to} TR ₆ and the reflux diodes D ₄ to D ₆ between the common anode terminals.

The electric motor 2 is a synchronous motor composed of a brushless direct current motor and using a two-pole permanent magnet as a magnetic field. Winding current flowing in the armature winding of the electric motor (2) is adapted to detect a winding current (I _L) flowing in the low-resistance (R _1), by a voltage drop of the low-resistance (R _1).

The control unit for controlling the rotational speed and the angular speed of the motor 2 controls the torque of the operational memory circuit 22, the magnetic pole position detection circuit 26 for detecting the magnetic pole position of the rotor of the electric motor 2, and the motor 2; The target rotational speed is supplied to the torque control circuit 25 and the base driver 24 for the transistors TR ₁ to TR ₆ and the operational memory circuit 22 which change the angular speed by changing the plurality of times while the main shaft ₆ rotates one time. And a speed command circuit 27 for commanding, an electronic pickup 20 and a waveform shaping circuit 21 for detecting a change in the rotational speed of the rotor spindle.

The magnetic pole position detection circuit 26 is a circuit for forming a position detection signal S ₂ corresponding to the rotor position using a filter circuit from the armature winding terminal voltages V _A to V _C of the electric motor 2. .

The arithmetic memory circuit 22 is composed of a CPU 22a, a ROM 22b, a RAM 22c, an interface, and the like, and is connected by an address bus, a data bus, and a control bus (not shown), respectively.

4 shows the details of an example of the torque control circuit 25, which has a D / A converter 28 as a current command circuit, an amplifier 29 as a current detection circuit, a hysteresis characteristic, and a characteristic as a comparison circuit. And a comparator 30 as a comparison circuit.

The 8-bit deviation angular velocity data or deviation time data S _O read out from the RAM 22c of the operational memory circuit 22 is converted into an analog amount by the D / A converter 28 described above, and This is the current command value 28a.

The winding current I _L obtained as the voltage drop of the low resistance R ₁ is amplified by the amplifier 29 to become the current detection value V _IL , and the comparator 30 makes the current command value 28a. ), The chopper signal S ₁ is formed as the output of the comparator 30.

Next, the operation of the present embodiment will be described.

The motor 2 started up in FIGS. 1, 2 and 3 gradually increases until it reaches a preset rotation speed set by the rotation speed control circuit 23, for example, 3000 revolutions per minute (rpm). do. After the set rotation speed is reached, the temperature T and the target temperature t ₀ in the to-be-cooled chamber detected by the temperature detector 31 installed near the evaporator 18 may be changed to a predetermined temperature. Is different, the rotation speed N of the electric motor 2 is controlled to increase or decrease the difference. The details will be described with reference to FIGS. 7 and 8.

As shown in FIG. 7, when the temperature T detected by the temperature detector 31 is now Δt ₁ (Δt ₁ having a temperature width of ± x) than the set temperature t ₀ , the rotational speed and set to ₁ ΔN calculation storage circuit 22 to a speed increasing as to the current rotation speed (N) of, again, like the case of Δt _2, the ΔN ₂ is set. As shown in FIG. 8, the rate of change of the rotational speed with respect to time varies depending on the increase and decrease of the rotational speed N, that is, the magnitude of ΔN. The larger the increase and decrease of the rotational speed ΔN, the larger the rate of change of the rotational speed.

In the present embodiment, the motor 2 can change the rotational speed continuously or stepwise from approximately 700rpm to 7000rpm, and no matter which rotational speed is operated therebetween, the set temperature t ₀ and the temperature detector 31 If there is a difference between the detected temperatures, the rotational speed of the motor 2 is increased or decreased to bring this difference to zero.

Next, the compression operation (suction, compressed discharge) is performed once during the rotation of the main shaft 6, for example, to follow the change in the compression torque required for the compression of the gas and to control the electronic torque that is the driving force. The operation of the case will be described.

Continuously changing the electronic torque of the electric motor 2 in a short time of one rotation makes it difficult to achieve the purpose of torque control that the difference between the compression torque and the electronic torque is substantially zero, regardless of the rotational angle of the main shaft. The circuit configuration for controlling the torque or the electronic torque becomes very complicated. In order to avoid this, in the embodiment of the present invention, one rotation (2π radians) is divided into a number equal to, for example, the product of the number of poles and the constant of the electric motor 2, and the torque control is performed for each divided rotation angle range. will be. For example, if the number of poles of the electric motor 2 is 2 and the constant is 3, one rotation is divided into six equal parts, and if the number of poles is two constants, one rotation is divided into 12 equal parts. In addition, since it is easy to control the selection of the number of teeth of the tooth 19 according to the number of divisions (the number of divided rotation angle regions), in the embodiment of the present invention, the number of teeth of the tooth 19 is an integer multiple of the number of divisions. There are 48 of them.

The case where one rotation (2π radians) of the main axis is divided into 12 is described below.

In the driving state, the electronic pickup 20 outputs a signal having a waveform as shown in FIG. 9A (same as FIG. 5). The waveform signal is shaped by the waveform shaping circuit 21 into a square wave as shown in FIG. 9B and input to the arithmetic memory circuit 22. The arithmetic memory circuit 22 calculates, from the rotational speed information when the waveform signal is input, the reference time t ₀ required for the main shaft 6 to rotate by the coincidence of the gears 19, and at the same time, Deviation (T ₀ to t ₁ ), (T) by comparing time (t ₀ ) and time (t ₁ ), (t ₅ ), (t ₆ ), while passing across the reference axis of the square wave ₀ to t ₅ ), (T ₀ to t ₉ ), ‥‥‥‥, and then, on the basis of the magnitude of the deviation (T ₀ to t ₁ ), the average compression torque in the divided rotation angle range The magnitude (target value) of the electronic torque is calculated. The torque control signal S ₀ corresponding to the obtained magnitude of the electronic torque is formed and sent to the torque control circuit 25.

Herein, an example of the calculation of the output torque magnitude is described in detail. For example, when the deviations (T ₀ to t ₁ ), (T ₀ to t ₅ ), ..................... are large values, the deviation (T ₀₎ The increase in ˜t ₁ ), (T ₀ ˜ t ₅ ), ‥‥‥‥ indicates that the difference between the load torque and the output torque at that time is large, in other words, the load torque is large and the degree of change of the load torque It is a sign of severeness.

Therefore, when calculating the output torque, the electronic torque is increased by the value according to the magnitudes of the deviations (T ₀ to t ₁ ), (T ₀ to t ₅ ), ... As a result, the result is an average value of the compression torque for the divided rotation angle range, and the average value of the compressed torque and the electronic torque for each divided rotation angle range are almost equal. In the torque control circuit 25, the torque control signal S ₀ is compared with the current detection value V _IL actually flowing in the motor 2, where S ₀ > VI _L , i.e., the electronic torque is smaller than the compressed torque. If ON is continued and S ₀ < VI _L , i.e., the electronic torque is greater than the compression torque, a chopper signal S ₁ which continues OFF is formed and sent to the base driver 24. The base driver 24 operates so that the base current flowing through the transistor TR ₁ of the rotational speed control circuit 23 continuously increases while the chopper signal S ₁ of ON is applied, and the chopper signal of OFF is applied. In operation, the base current flowing through the transistor TR ₁ of the rotational speed control circuit 23 continues to drop.

In the first divided rotation angle range n ₁ , as shown in FIG. 9C, in the first area n _1a , the main shaft 6 rotates the first value of the gear 19. The time t ₁ required to do so is detected. The time t ₁ detected in this detection area n _1a is processed as described above, and the rotation angle area of the torque control performed by this result is the remaining control except for the first detection area n _1a . The area n _1b and the next divided rotation angle range, that is, the range of the second detection region n _2a . With this operation, the electromagnetic torque and the compressed torque are applied to the _first divided rotation angle range n ₁ . The electromagnetic torque of the electric motor 2 is controlled so that the difference of the motors becomes substantially zero. In the second divided rotation angle range n ₂ , the time t ₅ required for the fifth hinge of the gear 19 to rotate is In the third divided rotation angle range, the time t ₉ required for the ninth hinge to rotate is inputted and processed as described above, and the difference between the compression torque and the residual torque is substantially different for each divided rotation angle. The output torque of the motor (2) should be Each controlled.

10 shows the result of the output torque control as described above. In this figure, the horizontal axis represents the rotation angle (rad) of the main axis, the vertical axis represents the torque, and the solid line represents the change of the electronic torque of the electric motor 2, and the dotted line represents the change of the load torque.

Figure 11 shows the torsional vibration characteristics of the change in the main shaft rotational speed of the electric compressor to which the present invention is applied, according to the present invention, even in the rotational speed range of 700rpm to 2000rpm that is 2000rpm or less to the same vibration characteristics as the area of 2000rpm or more You can do it.

Therefore, in the above embodiment, the torque control for each divided rotation angle range is effective only in the range in which the torsional vibration increases, for example, in the rotational speed range of about 2000 rpm or less, and other than that.

In Fig. 11, the dotted line is the vibration characteristic of the conventional electric compressor.

12 and 13 show Examples 2 and 3 of the present invention, respectively.

12 shows that the fixing mechanism 33 is attached to the case 1, the supporting mechanism 33 is supported by the supporting member 35 provided on the base 34, and the compressor is installed horizontally. At the same time, the main part of Embodiment 2 which showed the load detector 36 between the support member 35 and the fixing mechanism 33 is shown. Reference numeral 37 denotes a suction pipe.

FIG. 13 shows the embodiment 3 in which the fixing mechanism 33 installed in the case 1 is supported by the support member 35 fixed to the base 34 and the deformation detector 38 is installed in the support member 35. It shows the main part.

When the compressor is operated, rotational vibration is induced in the case 1, and each of the detectors 36 and 38 has a response signal as shown in Fig. 14 (a change in the load in the second embodiment and a deformation in the third embodiment). The response signals corresponding to the load torque of the compressor (see dashed line in FIG. 10) are evident from the experimental results of the inventors, and the feedback control device as shown in Example 1 (see FIG. 2) By controlling the response signal shown in FIG. 14 to be substantially zero, the vibrations of the compressor can be suppressed also in the second and third embodiments.

In addition, although FIG. 12 and FIG. 13 made the compressor into the horizontal installation state, it is not limited to a horizontal installation, The vertical installation and the diagonal installation are also possible.

In addition, the present invention is to control the electronic torque of the transmission element in accordance with the load, and to reduce the rotational vibration of the rotation system, the load need not be a compressor, it can be applied to the whole rotation system with a load variation. Furthermore, in performing torque control, it is not necessary to match the load torque and the output torque if there is an allowable value in the amount of rotational vibration reduction, and it is effective to reduce the vibration only by approximating and controlling the pattern per one cycle.

15 is a diagram showing Example 4 of the present invention. In this figure, reference numeral 39 denotes a pressure sensor for detecting the pressure change of the gas in the compression angle chamber, and is installed near the discharge torque of the cylinder. Other than that is the same as that of the compressor of the first embodiment (see Figs. 1 and 2), the same reference numerals are used and the description thereof is omitted.

Reference numeral 40 denotes a pressure through hole extending from the pressure operating chamber 13 to the discharge port. By this pressure sensor 39, the pressure fluctuations in the compression operation chamber can be obtained as shown in FIG. The pressure sensor 39 is connected to the operational memory circuit 22 of the torque control device shown in FIG. 3, and is calculated by the operational memory circuit 22 to obtain a change in load torque as shown in FIG. . A signal corresponding to the magnitude of the load torque is output to the torque control circuit 25. This is in place of the deviation signal S ₀ . Other than that is the same as that of Example 1.

The operation memory circuit 22 receives a signal from the pressure sensor 39 and outputs a signal such as a load torque of the compressor, but a torque within a range sufficient to control the rotational vibration is output even if not equal to the load torque. It may be a signal, and a torque pattern obtained by synthesizing the primary component, the primary component and the secondary component of the load torque of the compressor, and the n-th component from the primary component may be output. FIG. 18 shows Fourier expansion of the load torque when the compressor is operated under a certain pressure condition. The first to third components are shown. Curve A is the primary component, curve B is the secondary component, Curve C shows the tertiary components, respectively.

And in FIG. 18, the level used as the reference | standard of a government has the magnitude | size of zero order component. 19 is a diagram showing the torque difference between the absorption torque of the compression element and the electromagnetic torque of the transmission element. Curve (a) shows the torque difference between the absorption torque and the electronic torque when the electronic torque of the transmission element is not controlled. Curve (b) shows the torque difference from the absorption torque when the primary component indicated by symbol A in FIG. 18 is output as electronic torque, and curve (c) is indicated by symbols A and B in FIG. 18, respectively. The torque difference with the absorption torque at the time of outputting the torque which synthesize | combined the primary component and the secondary component by the electronic torque is shown.

As can be seen from FIG. 19, the remaining torque which acts on the rotational system of the compressor when the torque control is performed (curve b, c) is compared with the case where the torque control of the transmission element is not performed at all (curve a). Since the difference between the load torque and the output torque) becomes small, the rotational vibration can be reduced even when the torque pattern based only on the primary component is output from the electric element (curve b). It is more preferable to synthesize from the primary component to the n-th component, but in practice, a synthetic torque pattern of about 1 to 2 components is sufficient. It is also possible to arbitrarily select a plurality of torque patterns (n = 1 to n) up to these n-th components.

Claims (2)

In a motor having a motor (2) having a rotor (7) and a stator (3) and a compressor driven through a main shaft coupled to the rotor (7) of the motor (2), the motor (2) A rotation speed control device 23 capable of supplying a current to the rotor 7 to rotate the rotor 7 and arbitrarily varying the rotation speed, and a torque detection circuit 25 for detecting a current supplied to the electric motor 2. The angular velocity detecting means comprising an electric pickup 20 and a waveform shaping circuit 21 for detecting the angular velocity of the main shaft 6, and the angular velocity detected by the angular velocity detecting means. The operation memory circuit 22 which calculates the rotation speed variation of (6) and calculates the current value of the output torque of the motor so that the rotation speed variation becomes zero, and the rotation angle of one rotation of the main shaft 6 is a plurality of rotation angles. For each of the divided angular ranges And a torque control device for forming a signal having a current value determined by the memory circuit (22) and outputting the signal to the rotation speed control device. In an electric motor drive compressor having a motor (2) having a rotor (7) and a stator (3) and a compressor driven through a main shaft (6) coupled to the rotor (7) of the motor (2), By supplying a current to the motor (2) to rotate the rotor (7) of the motor and at the same time detects the current supplied to the rotation speed control device 23 and the motor (2) which can arbitrarily vary the number of revolutions With respect to the electric current detection means such as the torque control circuit 25, the angle detection means consisting of the electronic pickup 20 and the waveform shaping circuit 21 for detecting the angular velocity of the main shaft (6), and the electric motor (2) RAM 22c, which stores a plurality of output torque patterns having one rotation of the main shaft as one cycle, and the rotational speed variation of the main shaft 6 are obtained from the angular velocity detected by the angular velocity detecting means, and the obtained rotational speed variation is obtained. The rotation of the output torque pattern which becomes zero Also a motor compressor having a torque control device characterized in that the output to the control device.

Images