JPH0746893B2 - Rotational position detector for compressor electric motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a compressor in which an induction motor and a compression element rotationally driven by a rotor of the induction motor are housed in the same case, and more particularly, The present invention relates to a detection circuit that detects the rotational position of this induction motor.

(B) Prior Art Generally, as a rotational position detecting device for an electric motor for a compressor, there is a device described in JP-A-63-23585. In the device disclosed in this publication, a gear or an encoder is directly connected to the rotary shaft of the electric motor, and a sensor for detecting a pulse generated by the gear is provided to detect the rotational position of the rotor.

(C) Problems to be Solved by the Invention In the rotational position detecting device for an electric motor configured as described above, the sensor must be provided inside the direct-coupled compressor, and therefore, the sensor has an anti-Freon property, an anti-temperature property, an anti-temperature property. There was a problem with the pressure property, and the life of this sensor could not be sufficiently secured. Therefore, there is a problem that the life of the compressor itself is shortened.

Further, although a product having improved anti-Freon property has been developed, a product having a sufficiently long life has not been secured.

In order to solve such a problem, the present invention provides a rotational position detecting device that does not cause a problem such as anti-Freon property even when a general-purpose type sensor is used.

(D) Means for Solving the Problem The present invention is a compression system in which an electric motor and a compression element which is connected to the electric motor via a rotary shaft and is driven by the rotary shaft are housed in a single hermetic container. In the machine, a disk rotating with the rotating shaft, a permanent magnet mounted on the disk, and a direction along the axial direction of the rotating shaft so that airtightness of the sealed container is maintained from the outside of the sealed container toward the permanent magnet. A bottomed cylinder inserted from the magnet, a magnetic detection element provided in the cylinder so as to detect the magnetism of a permanent magnet, and a control unit for determining the rotational position of the rotor from the output change of the magnetic detection element. Be prepared.

Further, the permanent magnet is attached at a position on the disk corresponding to the predetermined rotational position of the compression element.

Further, permanent magnets are mounted on the disk at positions corresponding to a plurality of predetermined rotational positions of the compression element.

Further, it is provided with an electric component attached to the outer wall of the closed container near the opening of the cylinder, and a single cover for simultaneously covering the electric component and the opening of the cylinder.

(E) Operation In the rotational position detecting device configured as described above, a general-purpose type sensor can be used for position detection without considering the anti-Freon property of the compressor.

(F) Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the compressor. In the figure, reference numeral 1 denotes a closed container, in which a compression element 4 and a three-phase induction motor 3 are housed. The three-phase induction motor 3 includes a stator 5 on which a three-phase winding is wound, and a rotor 6 that rotates by a magnetic field generated by the stator 5.
And consists of. The compression element 4 is connected to the shaft 13 of the rotor. The compression element 4 includes a crank portion 14 that rotates about a shaft 13 as a crankshaft 2, a roller 8 that rotates in the cylinder 7 by the crank portion 14, an upper bearing portion 10 and a lower bearing portion 11 that seal the opening of the cylinder 7. It is composed of a cup muffler 12 attached to the upper bearing portion. 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. Balancers 16 and 17 are provided so as to dynamically or statically balance with the crank portion 14 of the crankshaft 2. Reference numeral 18 denotes a discharge pipe, which is attached to the upper side of the closed container 1.

FIG. 2 is a II-II sectional view of the compressor shown in FIG.
In this figure, 19 is a discharge port and 20 is a suction port, and the spaces 21 and 22 in the cylinder 7 are divided into a high pressure chamber and a low pressure chamber, respectively. The roller 8 rotates in the direction of the solid line arrow in FIG. 2, and the contact position where the roller 8 contacts the cylinder 7 is indicated as 0 to 360 degrees as the rotational position. Second
In the state shown in the drawing, the contact position between the roller 8 and the cylinder 7, that is, the rotational position of the crankshaft 2 (shaft 13) is at a position of 180 degrees.

3 and 4 are a cross-sectional view and a top 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 an actual compressor. In this figure, the compression element 4 rotates simultaneously with the rotor 6 via the crankshaft 2 (rotor shaft 13). Therefore, if the rotation position of the rotor 6 is detected, the rotation position of the compression element 4 is actually determined. Can be detected. The position detector comprises a magnet 23 adhered to a disk 22 and a magnetic detector (Hall element) 24. The disk 22 is attached to the shaft 13 by bolts 25 so that the center of rotation is aligned. The positional relationship between the magnet 23 and the hall element 24 is such that the hall element 24 detects magnetism and changes the output when the rotational position shown in FIG. 2 is "0" degree. Therefore, the output of the compression element 4 (rotor) changes every rotation position of "0" degrees. The Hall element 24 is provided at the back of the pipe 50 by inserting a bottomed pipe 50 (cylindrical or polygonal) from the side surface side of the closed casing 1 of the compressor. Also, this pipe 50
Is welded to the closed container 1 so that high-pressure gas inside the compressor does not leak. Reference numeral 26 is a balance weight, which corrects the weight balance of the disk generated by mounting the hall element 24.

The pipe 50 is, for example, made of copper having a diameter that allows the Hall element 24 to be inserted therein, and has a bottomed shape by welding a cap to one end. The Hall element 24 is mounted on a substrate having a size that fits in the pipe 50 and then inserted into the pipe 50 together with this substrate.

Incidentally, FIG. 5 is a top view of the disk 22.

FIG. 6 is a control circuit diagram for controlling the operation of the compressor shown in FIGS. In this figure, 27 to 29 are stator windings of the induction motor 5, which are star-connected. A magnet attached to the rotor disk 5 by attaching a three-phase alternating current to the stator windings 27 to 29.
23 rotates. Therefore, every time the rotor 5 (compression element) makes one revolution, the output of the Hall element 24 changes, and the position detection circuit 30 converts this change into a signal and outputs it to the control unit 31. 32-
37 is a switching element that performs ON / OFF operation and is connected in a three-phase bridge shape, and the DC power supplied from the DC power supply 39 to the three-phase stator windings 27 to 29 is converted into three-phase AC power. Convert and output. These switching elements (semiconductor switching elements such as transistor elements, FET elements, and GTO elements) 32 to 37 discharge accumulated charge and the stator windings, respectively.
Diodes forming a circulating circuit in which circulating currents 27 to 29 flow are connected. The DC power supply 39 may be AC power (which may be a commercial power supply) rectified and smoothed, or DC power from a battery. The ON / OFF operation of the switching elements 32 to 37 is controlled by a signal from the control unit 31 given via the base drive circuit 38. This controller mainly consists of CPU, RAM, ROM, I
Speed command circuit 40
The frequency based on the speed signal from is calculated, and the ON / OFF operation of the switching elements 32 to 37 is controlled based on the PWM theory so that the AC power of this frequency is supplied to the stator windings 27 to 29. Hereinafter, ON / OFF control of the switching elements 32 to 37 for obtaining the AC power of the calculated frequency will be described. FIG. 7 shows ON for supplying to switching elements 32-37.
It is explanatory drawing which shows the process which produces an / OFF signal based on PWM theory. An ON / OFF signal of the switching elements 32 to 37 is obtained by modulating a sin waveform having a frequency equal to a desired frequency (three waveforms in FIG. 7 because there are three phases) and a triangular wave. At this time, the frequency of the triangular wave determines the resolution of the AC waveform output from the bridge circuit (the cycle at which the ON / OFF state of the switching element switches). That is, the higher the triangular wave frequency is, the better the resolution becomes.However, if the switching speed of the switching element is exceeded, the switching element becomes inoperable.Therefore, the triangular wave frequency is an appropriate frequency in consideration of the switching element used. To set. As can be seen from this figure, the ON / OFF time of each switching element changes when the amplitude of the triangular wave and the amplitude of the sin wave are set appropriately. As a result, the longer the ON time of the switching element, the larger the voltage amplitude of the AC power output from the bridge circuit. That is, the output voltage becomes high. At this time, the frequency of the triangular wave may be changed with respect to the frequency of the sin wave. The generation of the switching signal is not limited to the above-described method, and any method can be used as long as it can output AC power of a desired frequency and can arbitrarily change the output voltage of this AC power during one cycle of AC.

Therefore, when such a waveform generation method is used, the AC power P is f
(= Output frequency), V (= output voltage), Ph (= output phase). That is, the ON / OFF signals of the switching elements 32-37 are calculated based on such conditions. Note that f is a frequency calculated from the speed signal given from the speed command circuit, and the basic value of V is determined based on the value of f so that V / f = constant value. Are set so that the operating efficiency of the induction motor or compressor is good at each frequency. As the Ph value changes from 0 to 360 °, one cycle of AC power is output. If the advance amount ΔPh of Ph is increased, the resolution in one cycle becomes worse, and if this value is made smaller, the resolution becomes better, but the value of ΔPh depends on the switching time at which the switching element can respond and the processing capacity of the control unit 31. From the relationship of, the optimum ΔPh for each frequency
The value of is preset.

FIG. 8 shows a control unit 31 when outputting AC power of frequency f.
3 is a flowchart showing the operation of FIG. In this flowchart, it is first determined in step S1 whether the frequency f has been changed. That is, it is determined whether or not the speed signal given from the speed command circuit 40 has been changed. When the frequency f is changed, the process proceeds to step S2, V (basic value of output voltage) and ΔPh (phase advance amount) are calculated and changed. Then, it proceeds to step S3. In this step, it is determined whether or not there is a signal from the position detection circuit. That is, it is determined whether or not the compression element of the compressor (rotor of the induction motor) has reached the rotational position of "0" degrees. When this signal is received, the process proceeds to step S4. In this step, the phase Ph is set to "0" and the rotational position of the rotor is aligned. At the same time, the rotational speed N of the rotor is calculated from the signal input last time and the signal input this time. If there is no signal in step S3, the process proceeds to step S5. Phase in this step
Advance the Ph value by ΔPh. Next, in step S6, the phase Ph
Judge whether it is between Phh and Ph1. When the phase Ph satisfies the condition of step S6, the process proceeds to step S7, where the value of V is increased by + VU (about 20% of the value of V),
Increase the value of f by + fU (5 to 7% of the value of f),
Increase the value of Ph by the value of PhU (about 10 degrees). Step S
When the condition of 6 is not satisfied, the process proceeds to step S8, the value of V is decreased by −VD (10 to 20% with respect to the value of V), and the value of f is decreased by −fD (5 to 7 with respect to the value of f. %) Decrease. By performing steps S6 to S8 as described above, when the rotor is in the rotation section between the rotation position corresponding to the phase Ph1 and the rotation position corresponding to the phase Phh, the stator winding, that is, the motor of the compressor is supplied. The frequency and voltage of the generated AC power increase and the drive torque of this electric motor increases. At other times, the drive torque is reduced. Therefore, when the compression element is in the compression process and the electric motor requires a large torque, the torque can be increased. The values of Ph1 and Phh will be described later. Next, in step S9, it is determined whether or not the rotation speed N of the rotor calculated in step S4 is a value (ROLL) smaller than the value given by the speed command circuit by a predetermined value. The ratio of the ROLL value to N may be different for each frequency, or may be a constant ratio. When the rotation speed N is low, the process proceeds to step S10. In this step, the values of V, f, Ph are corrected to the + side. Then step
In step S11, it is determined whether the rotation speed N of the rotor calculated in step S4 is a value (ROLH) larger than the value given by the speed command circuit by a predetermined value. The ratio of the value of ROLH to N may be different for each frequency, or may be a constant ratio or a constant value.
When the rotation speed N is high, the process proceeds to step S12. In this step, the values of V, f, Ph are corrected to one side. The correction width in step S10 and step S12 is 0.1-
It is 0.5 volts and the frequency is about 0.1 to 0.5 Hz. Step S
13 is an output step of the switching signal. In this step, f, obtained by the above steps,
Based on the values of V and Ph, the ON / OFF states of the switching elements 32 to 37 are maintained for a fixed time (one cycle time / 360 / ΔPh). (When the minimum unit of Ph is 12 degrees) For example, the switching signal for one cycle based on this flowchart is as shown in FIG.

FIG. 9 is a voltage waveform diagram of AC power obtained when the flowchart shown in FIG. 8 is executed. This voltage waveform V27,
V28 and V29 are voltages supplied to the stator windings 27 to 29 of the induction motor, and as an example, the case where the voltage waveform is in the phase state as shown in FIG. 9 will be described. "0" degree in the figure is when a signal is output from the position detection circuit. That is, when the position of the magnet provided on the rotor and the position of the Hall element match. V = V + VU, f = f + fU when the phase angle becomes Ph1 (the position of this phase Ph1 is obtained from the time of one period obtained from the number of rotations of the rotor and the time corresponding to the rotational position) in this one period. , Ph = Ph + PhU, the voltage waveform is raised like the dotted line. The voltage waveform of this dotted line is VU [V] larger than the basic voltage waveform (voltage waveform of the solid line), and the frequency is fUHz higher than the basic frequency.
Moreover, the phase is advanced. That is, the phase angle Ph1 of the voltage waveform shown by the dotted line leads the phase angle Ph1 of the voltage waveform shown by the solid line by about 10 degrees. The phase angle between Ph1 and Phh corresponds to the compression process of the compression element and requires a large torque.

FIG. 10 is a vibration characteristic diagram showing a vibration state of the compressor when driving the compressor. This vibration is obtained from the output of the acceleration sensor mounted on the compressor.
The operating conditions at this time are those when the frequency of the AC power supplied to the stator winding is 30 Hz. In this figure OF
The F side (left side of the dotted line) is when the control method according to the present invention is not used, and the ON side (right side of the dotted line) is when the control method of the present invention is used. It can be seen that the amplitude of vibration is reduced from LOFF to LON (reduced to about 1/3) by using the control method of the present invention. That is, the vibration is small.

Figure 12 shows the phase angles Ph1 and Phh when the compressor is driven at 30 Hz.
It is a characteristic view which shows the relationship between a vibration waveform. In this figure, the waveform of i is a vibration waveform when the control method of the present invention is not used. There is a peak of vibration amplitude at a phase of 130 degrees (almost equal to the rotational position) and at a phase of 270 degrees. The waveform of ii uses the control method of the present invention, Ph1 = 100 degrees, Ph
This is a vibration waveform when h = 250 degrees. iii is also Ph1
= 130 degrees and Phh = 270 degrees, the vibration waveform is iv
Similarly, is a vibration waveform when Ph1 = 150 degrees and Phh = 300 degrees. From these results, Ph1 is about 130 degrees, Phh is about 270 degrees, that is, the values of Ph1 and Phh are near the phase where the vibration amplitude peaks when the control method according to the present invention is not used (the compression element of the compressor is (When the compression process is performed) is an appropriate value, and the vibration of the compressor can be reduced. Therefore, noise can be reduced at the same time as the vibration is reduced.

Although the torque of the induction motor is increased by one step between the phases (rotational positions) Ph1 and Phh in the above embodiment, the torque may be increased in two steps in this section, or the torque in this section may be increased. The torque may be gradually increased including the front and rear sections.

FIG. 12 and FIG. 13 are a sectional view and a top view of a main part showing another embodiment of the rotational position detecting device. The difference from the cross-sectional view shown in FIG. 3 is that a bottomed pipe 42 is inserted along the shaft 13 of the rotor 6 from the upper side of the closed container 1 and the discharge pipe 18 side. 42 is a Hall element, 43 is a hermetic terminal of the compressor, 44 is a mounting bottle, and a resin cover is attached so as to cover the hermetic terminal and the opening of the pipe 41. By covering the pipe 42 with a cover, it is possible to prevent dust and rainwater from entering the pipe 41.

FIG. 14 and FIG. 15 are top views of the disk showing another state in which a permanent magnet is attached to the disk. FIG. 14 shows the permanent magnets 45 and 46 provided at positions where signals are output when the rotor rotation positions reach 130 degrees and 270 degrees. When the permanent magnet is attached in this way, the output voltage of the AC power may be changed in accordance with the change in the output of the Hall element, so that the rotational position calculation becomes unnecessary and the control device can be simplified. Further, FIG. 15 shows the permanent magnets 47 and 48 mounted at the rotational positions of the rotor of 0 ° and 180 °. By mounting the permanent magnets in such a position, the rotational position of the rotor can be corrected twice in one rotation to calculate an accurate rotational position.

(G) Effect of the Invention According to the present invention, in a rotor position detecting device, a disk is mounted so as to rotate together with a rotation shaft, a permanent magnet is mounted on the disk, and the permanent magnet is sealed from the outside of a hermetic container. Since it is composed of a bottomed cylinder inserted from the direction along the axial direction of the rotating shaft so that the airtightness of the container is maintained, and a magnetic detection element attached to this cylinder so as to detect the magnetism of the permanent magnet, Since the magnetic detection element does not come into direct contact with the working refrigerant in the compressor, a general-purpose type magnetic detection element can be used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a compressor using the control system of the present invention, FIG. 2 is a sectional view taken along the line II-II of the compressor shown in FIG. 1, and FIG. 3 is an actual compression. FIG. 4 is a cross-sectional view of an essential part showing a state in which a position detector is attached to the machine, FIG. 4 is a top view of the compressor shown in FIG. 3, and FIG. 5 is a top view of the disk shown in FIG. Is a control circuit diagram for controlling the operation of the compressor shown in FIGS. 1 to 3, FIG.
The figure is an explanatory view showing ON / OFF signals of switching elements, 8th
6 is a flow chart showing the operation of the control unit shown in FIG. 6, FIG. 9 is a voltage waveform diagram of AC power obtained when the flow chart shown in FIG. 7 is executed, and FIG. FIG. 11 is a vibration characteristic diagram showing the vibration state of the compressor when the compressor is operating, FIG. 11 is a vibration characteristic diagram when the compressor is driven at 30 Hz, and FIG. 12 is another example showing the mounting state of the Hall element. FIG. 13 is a top view of the compressor shown in FIG. 12, FIG. 14 is a top view showing another embodiment of the disk attached to the rotor, and FIG. 15 is a rotor. FIG. 9 is a top view of a disk according to still another embodiment attached to the disk. 1 ... Compressor, 2 ... Compression element, 5 ... Induction motor, 6
...... Rotor, 23 …… Magnet, 24 …… Hall element, 27
~ 29 ...... Stator winding, 30 ...... Position detection circuit, 31 ...... Control part, 32-37 ...... Switching element, 40 ...... Speed command circuit, 50 ...... Pipe.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-63-23585 (JP, A) Actually opened 57-186682 (JP, U) Actually opened 62-121566 (JP, U)

Claims (4)

[Claims] 1. A compressor comprising an electric motor and a compression element, which is connected to the electric motor via a rotary shaft and is driven by the rotary shaft, accommodated in a single hermetically sealed container, and rotates together with the rotary shaft. A disk and a permanent magnet mounted on this disk,
A bottomed cylinder inserted from the outside of the closed container toward the permanent magnet in a direction along the axial direction of the rotary shaft so as to maintain the airtightness of the closed container, and the magnetism of the permanent magnet can be detected in this cylinder. A rotational position detecting device for a motor for a compressor, comprising: a magnetic detecting element provided as described above; and a control section for obtaining a rotational position of a rotor from a change in output of the magnetic detecting element. 2. The rotational position detecting device for a compressor electric motor according to claim 1, wherein the permanent magnet is mounted at a position on the disk corresponding to a predetermined rotational position of the compression element. . 3. The electric motor for a compressor according to claim 2, wherein permanent magnets are mounted on the disk at positions corresponding to a plurality of predetermined rotational positions of the compression element. Rotational position detector. 4. An electric component mounted on the outer wall of the closed container near the opening of the cylinder, and a single cover for simultaneously covering the electric component and the opening of the cylinder.
Item 7. A rotational position detection device for a compressor electric motor according to the item.