JP2012095474A - Permanent magnet embedded type electric motor and hermetically sealed type compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-vibration and low-noise permanent magnet embedded type electric motor having a favorable demagnetization characteristic.SOLUTION: A permanent magnet embedded type electric motor according to the present invention includes: a stator and a rotor arranged on an inner peripheral side of the stator with a gap therebetween. The rotor includes: a rotor core produced by punching out a magnetic steel sheet in a predetermined shape to obtain pieces of the magnetic steel sheet and laminating a predetermined number of the pieces; a plurality of magnet insertion holes formed along an outer peripheral portion of the rotor core; permanent magnets inserted into the magnet insertion holes; a plurality of slits formed on an outer peripheral side of the magnet insertion holes; and end plates arranged for both end faces of the rotor core in a direction of the laminating, wherein in each set of the plurality of slits formed for one of the permanent magnets, each slit for suppression of demagnetization arranged on an extended line extending from an end face of the permanent magnet in a circumferential direction toward an outer peripheral side of the rotor core has a width in the circumferential direction that is wider than those of other slits formed within a width of the permanent magnet.

Description

  The present invention relates to a permanent magnet embedded electric motor. Specifically, the present invention relates to the shape of a slit disposed in the outer peripheral portion of the permanent insertion hole in the rotor of the permanent magnet embedded type electric motor. The present invention also relates to a hermetic compressor equipped with the permanent magnet embedded electric motor.

  Conventionally, in a permanent magnet type motor, a plurality of slits are formed at an equal pitch along the outer periphery of the rotor core, and the circumferential length of the slits is positioned at the end portion from the center portion of the rotor magnetic pole. There has been proposed a permanent magnet type motor which is set so as to increase in order of vibration and suppress the generation of vibration and noise (see, for example, Patent Document 1).

JP 2001-37127 A

  However, the permanent magnet motor of Patent Document 1 has a slit circumferential length that is gradually increased from the central portion to the end portion. There was a problem that the interlinkage magnetic flux of the magnet decreased and the efficiency decreased.

  The present invention has been made to solve the above-described problems, and provides a highly reliable embedded permanent magnet electric motor having high efficiency and improved demagnetization characteristics against a demagnetizing field from a stator. To do. Also, a hermetic compressor using the permanent magnet embedded motor is provided.

The permanent magnet embedded electric motor according to the present invention is:
After punching the magnetic steel sheet into a predetermined shape, a stator core manufactured by stacking a predetermined number of sheets, a plurality of stator slots formed along the inner periphery of the stator core, and inserted into the stator slot A stator having windings; and
A rotor disposed on the inner peripheral side of the stator via a gap,
The rotor is
After punching the magnetic steel sheet into a predetermined shape, a rotor core manufactured by laminating a predetermined number of sheets,
A plurality of magnet insertion holes formed along the outer periphery of the rotor core;
A permanent magnet to be inserted into the magnet insertion hole;
A plurality of slits formed on the outer peripheral side of the magnet insertion hole;
An end plate disposed on both end faces of the rotor core in the stacking direction;
Of the plurality of slits, the demagnetization suppression slit disposed on the extension line extending from the circumferential end surface of the permanent magnet to the outer peripheral side of the rotor core is formed within the width of the single-pole permanent magnet. Compared to other slits, the circumferential width of the demagnetization suppressing slit is made wider than the circumferential width of the other slits.

  In the permanent magnet embedded electric motor according to the present invention, among the plurality of slits, the demagnetization suppressing slit disposed on the extension line extending from the circumferential end surface of the permanent magnet to the outer peripheral side of the rotor core is In comparison with other slits formed within the width of one permanent magnet, the circumferential width of the demagnetization suppression slit is wider than the circumferential width of the other slits. A highly reliable permanent magnet embedded motor with low vibration and noise and good demagnetization characteristics against the demagnetizing field of the stator can be obtained.

FIG. 3 shows the first embodiment and is a cross-sectional view of the permanent magnet embedded motor 100. FIG. The A section enlarged view of FIG. FIG. 5 shows the first embodiment, and is a cross-sectional view of the stator 12. FIG. 5 shows the first embodiment, and is a cross-sectional view of the stator core 12a. The B section enlarged view of FIG. FIG. 3 shows the first embodiment and is a cross-sectional view of the rotor 11. CC sectional drawing of FIG. FIG. 3 shows the first embodiment and is a plan view of the rotor 11. Fig. 5 shows the first embodiment, and is a plan view of an end plate 11d. FIG. 5 shows the first embodiment and is a cross-sectional view of the rotor core 11a. The elements on larger scale of FIG. The elements on larger scale of FIG. The elements on larger scale of FIG. FIG. 3 shows the first embodiment and is a torque characteristic diagram of the embedded permanent magnet electric motor 100. FIG. FIG. 3 shows the first embodiment, and is a longitudinal sectional view of a scroll compressor 300. FIG. 3 shows the first embodiment, and is a circuit diagram of a drive circuit 1 of a permanent magnet embedded electric motor 100. FIG.

Embodiment 1 FIG.
1 and 2 are diagrams showing the first embodiment, in which FIG. 1 is a transverse sectional view of the permanent magnet embedded electric motor 100, and FIG. 2 is an enlarged view of a portion A in FIG.

  The configuration of the permanent magnet embedded motor 100 will be described with reference to FIGS. 1 and 2.

  A permanent magnet embedded type electric motor 100 shown in FIG. 1 is a three-phase six-pole brushless DC motor. The embedded permanent magnet electric motor 100 includes a stator 12 and a rotor 11. Hereinafter, the permanent magnet embedded type electric motor 100 may be simply referred to as a motor or an electric motor.

  As shown in FIG. 2, a gap 60 having a predetermined radial dimension is provided between the stator 12 and the rotor 11. For example, the gap 60 between the stator 12 and the rotor 11 has a radial dimension of about 0.2 to 2.0 mm.

  FIG. 3 is a cross-sectional view of the stator 12 showing the first embodiment. As shown in FIG. 3, the stator 12 includes a substantially cylindrical (doughnut-shaped) stator core 12a and a U-phase winding 20a inserted into a stator slot 12b (18 slots) of the stator core 12a. And a three-phase winding composed of a V-phase winding 20b and a W-phase winding 20c. For the U-phase winding 20a, the V-phase winding 20b, and the W-phase winding 20c, generally, a magnet wire or the like in which an outer periphery of a copper wire is coated is used. However, it is not limited to the three-phase winding.

  The stator slot 12b has an insulating material for ensuring electrical insulation between the winding 20 (U-phase winding 20a, V-phase winding 20b and W-phase winding 20c) and the stator core 12a. (For example, slot cells, wedges, etc.) are inserted, but are not shown here.

  As shown in FIG. 3, each winding 20 (U-phase winding 20a, V-phase winding 20b, and W-phase winding 20c) is configured to straddle several stator slots 12b (stator teeth 12e). Has been. In the example shown in FIG. 3, one winding 20 is configured across three stator teeth 12 e. Such a winding method is generally called distributed winding.

  Inside the stator slot 12b, the U-phase winding 20a, the V-phase winding 20b, and the W-phase winding 20c are arranged in order from the outer peripheral side. However, the order is not particularly limited.

  The U-phase winding 20a, the V-phase winding 20b and the W-phase winding 20c are connected by Y connection (star connection, star connection), and a permanent magnet embedded type is applied by applying a three-phase voltage to each winding. The electric motor 100 generates torque.

  4 and 5 are diagrams showing the first embodiment. FIG. 4 is a transverse sectional view of the stator core 12a. FIG. 5 is an enlarged view of a portion B in FIG. As shown in FIG. 4, the stator core 12a is formed by punching a magnetic steel sheet having a thickness of about 0.1 to 1.5 mm into a predetermined shape, then laminating a predetermined number of sheets in the axial direction, Made fixed.

  Stator slots 12b are formed along the inner peripheral edge of the stator core 12a. The 18 stator slots 12b are arranged at substantially equal intervals in the circumferential direction. In the example of FIG. 4, all the stator slots 12b have the same shape, but may be configured in a large and small slot shape in which a part of the size is changed.

  Between adjacent stator slots 12b, a stator tooth portion 12e, which is a part of the stator core 12a, is formed. Therefore, the number of stator slots 12b and the number of stator teeth 12e are the same. In the example of FIG. 4, the stator core 12a includes 18 stator slots 12b and 18 stator teeth 12e.

  As shown in FIG. 5, the stator tooth portion 12e is formed with a circumferential width Wt substantially constant. Therefore, the circumferential width of the stator slot 12b is gradually increased from the inner peripheral side toward the outer peripheral side.

  The stator slot 12b extending in the radial direction opens to the inner peripheral edge. This opening is referred to as a slot opening 12d. The U-phase winding 20a, V-phase winding 20b, and W-phase winding 20c are inserted from the slot opening 12d.

  As shown in FIG. 4, on the outer peripheral surface of the stator core 12a, there are provided four stator cutouts 12c that form a substantially straight portion obtained by cutting out the outer circumference circularly into a substantially straight line. Adjacent ones of the four stator cutouts 12c are arranged at a substantially right angle. However, this is an example, and the number and arrangement of the stator notches 12c may be arbitrary.

  Further, in the stator core 12a, the outer core portion of the stator slot 12b is generally called a core back 12f. The magnetic path cross-sectional area of the core back 12f in the portion where the stator notch 12c is formed is smaller than the magnetic path cross-sectional area of the portion whose outer periphery is an arc shape.

  When the permanent magnet embedded type electric motor 100 of FIG. 1 is mounted on a hermetic compressor (for example, scroll compressor) used in the refrigeration cycle, the stator 12 is an inner periphery of a cylindrical hermetic container of the hermetic compressor. It is shrink-fit. Inside the hermetic compressor, refrigerant (including refrigeration oil) passes through the permanent magnet embedded motor 100. Therefore, the permanent magnet embedded type electric motor 100 requires a refrigerant passage.

  By providing the stator notch 12c having a substantially straight portion, a refrigerant passage is formed between the stator 12 and the sealed container. In the refrigerant passage of the permanent magnet embedded electric motor 100, in addition to the stator notch 12c on the outer peripheral surface of the stator core 12a, for example, the slit 40, the air hole portion 11b, and the stator 12 of the rotor 11 described later. There is a gap 60 (see FIG. 2) between the rotor 11 and the rotor 11.

  6 to 13 show the first embodiment. FIG. 6 is a transverse sectional view of the rotor 11, FIG. 7 is a sectional view taken along the line CC in FIG. 6, FIG. 8 is a plan view of the rotor 11, and FIG. 10 is a plan view of the end plate 11d, FIG. 10 is a cross-sectional view of the rotor core 11a, FIG. 11 is a partially enlarged view of FIG. 10, FIG. 12 is a partially enlarged view of FIG. is there.

  Since the present embodiment is characterized by the rotor 11, the rotor 11 will be described in detail below with reference to FIGS. The rotor 11 is provided on the inner peripheral side of the stator 12 via a gap 60 (see FIG. 2).

The rotor 11 includes the following elements.
(1) Rotor core 11a;
(2) permanent magnet 11c;
(3) end plate 11d;
(4) Rivet 11e;
(5) Rotating shaft 90.

  As shown in FIGS. 7 and 8, end plates 11d are provided at both ends of the rotor core 11a in the stacking direction to prevent the permanent magnets 11c from jumping out of the magnet insertion holes 11f, and the rotor cores are formed by rivets 11e. 11a and end plate 11d are integrated.

  As shown in FIG. 9, the end plate 11d has a substantially hexagonal plate shape (predetermined thickness), a shaft hole 11j at the center, air holes 11k (for example, four) around the shaft hole 11j, and rivets. Rivet insertion holes 11m (for example, four) into which 11e is inserted are formed. A nonmagnetic material (for example, stainless steel) is used for the end plate 11d. The same end plate 11d is provided at both axial ends of the rotor core 11a.

  As shown in FIG. 10, the rotor core 11a is formed by punching electromagnetic steel sheets having a plate thickness of 0.1 to 1.5 mm into a predetermined shape and laminating them in the axial direction in the same manner as the stator core 12a, and removing and caulking and bonding. It is fixed and manufactured by etc. Usually, the electromagnetic steel sheet of the inner side (inner peripheral side) of the stator core 12a is used.

  Generally, the rotor core 11a is often punched from the same material as the stator core 12a, but the material of the rotor core 11a may be different from the material of the stator core 12a. For example, a highly efficient embedded permanent magnet motor 100 that is inexpensive and has reduced iron loss by setting the thickness of the rotor core 11a to 0.5 mm and the thickness of the stator core 12a to 0.35 mm. Obtainable.

  The rotor iron core 11a is provided with six magnet insertion holes 11f, and six plate-like permanent magnets 11c are inserted into the magnet insertion holes 11f to form a six-pole rotor 11. Moreover, although mentioned later for details, the slit 40 is formed in the iron core part which exists in the outer peripheral side of the magnet insertion hole 11f. Further, a shaft hole 11g into which the rotating shaft 90 is fitted is formed at a substantially central portion of the rotor core 11a, and air hole portions 11b (for example, four pieces) and rivets 11e are provided between the shaft hole 11g and the magnet insertion hole 11f. Rivet insertion holes 11h (for example, four) to be inserted are formed.

  As the permanent magnet 11c, a rare earth permanent magnet mainly composed of neodymium, iron, or boron is preferably used, but a permanent magnet using another material (for example, ferrite or samarium) may be used.

  After the permanent magnet 11c is inserted into the magnet insertion hole 11f of the rotor core 11a, end plates 11d are arranged at both ends in the stacking direction of the rotor core 11a, and rivets provided on both the rotor core 11a and the end plate 11d. The rotor 11 is manufactured by inserting the rivet 11e into the insertion holes 11h and 11m.

  As shown in FIG. 11, the slit 40 formed in the iron core part which exists in the outer peripheral side of the magnet insertion hole 11f of the rotor iron core 11a is comprised by several slit 40a-40e. For example, a total of ten slits 40a to 40e are provided symmetrically on both sides of the magnetic pole center line. The slit 40a is provided at the end of one magnetic pole and has a role of suppressing leakage of magnetic flux inside the rotor of the permanent magnet 11c. The plurality of slits 40a to 40e are sequentially arranged from the end of one magnetic pole toward the magnetic pole center. The slit 40e is closest to the magnetic pole center.

  The slits 40b to 40e smooth the magnetic flux distribution of the iron core portion on the outer peripheral side of the magnet insertion hole 11f. For example, the slits 40b to 40e are parallel to the magnetization direction of the permanent magnet 11c (perpendicular to the magnet insertion hole 11f). ), And is formed so as to extend from the inner peripheral side of the rotor core 11a toward the outer peripheral side. However, the extending direction of the slits 40b to 40e may not be perpendicular to the magnet insertion hole 11f. For example, it may be toward the center of the magnetic pole. Furthermore, the shape of the slits 40b to 40e is substantially rectangular in cross section in the example of FIG. 11, but is not limited to this shape. Any shape such as an ellipse or a trapezoid may be used as long as the rotor core 11a is formed to extend from the inner peripheral side toward the outer peripheral side. In addition, although the slits 40a to 40e are provided symmetrically on both sides of the magnetic pole center line, they may be provided asymmetrically.

  By arranging the plurality of slits 40 (slits 40a to 40e), the magnetic flux distribution on the outer periphery of the rotor core 11a can be smoothed, and the harmonic component of the voltage induced in the winding 20 of the stator 12 Can be reduced.

  When the winding 20 is driven by applying a three-phase AC voltage, only the fundamental wave component of the voltage induced in the winding 20 of the stator 12 contributes effectively as the torque of the permanent magnet embedded motor 100. The harmonic component becomes torque pulsation (torque ripple).

  This torque ripple causes an increase in vibration and noise of the electric motor, but the permanent magnet embedded electric motor 100 with less vibration and noise can be obtained by arranging the plurality of slits 40a to 40e.

  As shown in FIGS. 12 and 13, among the plurality of slits formed within the width of the permanent magnet 11 c, a slit that is a non-magnetic material (air layer) on the circumferential extension of the permanent magnet 11 c. 40b is provided, and the circumferential width dimension Tb of the slit 40b is larger than the circumferential width dimension (Tc-Te) of the other slits 40c-40e formed within the width of the permanent magnet 11c. To form.

  When the permanent magnet 11c receives a large demagnetizing field from the stator 12, it causes irreversible demagnetization (hereinafter referred to as demagnetization), and there is a problem that the efficiency of the electric motor is lowered due to a decrease in the magnetic force of the permanent magnet 11c. In general, the demagnetization with respect to the demagnetizing field tends to be gradually demagnetized from the surface of the permanent magnet 11c on the side close to the stator 12, particularly near the corner of the circumferential end.

  Since the magnetic flux of the demagnetizing field of the stator 12 passes through the iron core having a low magnetic resistance, not only when the slit 40b is not present but also when the widthwise dimension Tb is small, the circumferential end of the permanent magnet 11c. May be demagnetized.

  In the present embodiment, the demagnetization characteristic against the demagnetizing field is set by setting the circumferential width dimension Tb of the slit 40b larger than the circumferential width dimension (Tc-Te) of the other slits 40c-40e. Thus, it is possible to obtain a highly reliable embedded permanent magnet electric motor 100 that is improved.

  Similarly to the circumferential width dimension Tb of the slit 40b, when the circumferential width dimensions (Tc to Te) of the other slits 40c to 40e are set to be large, it is possible to improve the demagnetization characteristic against the demagnetizing field. However, since the magnetic resistance of the main magnetic path of the permanent magnet 11c is increased, the magnetic flux of the permanent magnet 11c cannot be fully utilized, and there is a problem that the motor efficiency is lowered. However, since the circumferential width dimension (Tc to Te) of the slits 40c to 40e is set to be smaller than the circumferential width dimension Tb of the slit 40b, a highly efficient embedded permanent magnet electric motor is provided. 100 can be obtained.

  Here, the slit 40b disposed on the extension line extending from the circumferential end surface of the permanent magnet 11c to the outer peripheral side of the rotor core 11a is defined as a “demagnetization suppression slit”.

  Further, the other slits 40c to 40e formed within the width of the permanent magnet 11c are defined as “other slits formed within the width of the permanent magnet having one magnetic pole”.

  Further, as shown in FIG. 13, the minimum dimension between the slit 40b on the circumferential end extension line of the permanent magnet 11c and the magnet insertion hole 11f is T1, and the minimum dimension between the slit 40b and the outer periphery of the rotor core 11a. When the dimension is T2, T2> T1 is set.

  As described above, the magnetic flux of the demagnetizing field of the stator 12 tends to pass through the outer peripheral surface side of the rotor core 11a because it passes through the iron core portion of the rotor 11 having low magnetic resistance. Here, since T2 is made larger than T1, the magnetic flux of the demagnetizing field is less likely to be linked to the permanent magnet 11c, and the highly reliable embedded permanent magnet electric motor 100 with improved demagnetization characteristics is obtained. Can do.

  FIG. 14 is a diagram showing the first embodiment, and is a torque characteristic diagram of the permanent magnet embedded motor 100. The permanent magnet embedded motor 100 in which the rotor 11 is provided with the slit 40 and the permanent magnet embedded in which the slit 40 is not provided. It is the figure which compared the torque characteristic of the embedded type motor. FIG. 4 is a torque characteristic diagram when a three-phase AC voltage is applied to the winding 20, wherein the horizontal axis indicates the rotation angle and the vertical axis indicates the instantaneous torque.

  It can be seen that the motor without the slit 40 includes a large number of harmonic components in the voltage (induced voltage) induced in the stator winding, and thus the torque pulsation with respect to the rotation angle is large.

  By providing the slit 40, the harmonic component of the induced voltage induced in the winding 20 of the stator 12 can be reduced, so that the torque pulsation can be reduced and the permanent magnet embedded with less vibration and noise. The type motor 100 can be obtained.

  As shown in FIG. 8, when the rotor 11 is viewed from one end surface in the stacking direction, a part of the slit 40 can be visually recognized from the outer peripheral side of the end plate 11d, and the slit 40 is air that penetrates in the stacking direction. It is a layer (hole).

  Therefore, when the permanent magnet embedded type electric motor 100 is mounted on a hermetic compressor, a part of the slit 40 can be used as a refrigerant passage (flow path), so that a highly reliable refrigerant passage is ensured. A hermetic compressor can be obtained.

  FIG. 15 shows the first embodiment and is a longitudinal sectional view of the scroll compressor 300. As shown in FIG. 15, the scroll compressor 300 (an example of a hermetic compressor) includes at least a compression mechanism unit 200, an embedded permanent magnet electric motor 100, a compression mechanism unit 200, and a permanent magnet in a hermetic container 70. A rotary shaft 90 that couples the embedded electric motor 100, a subframe 71 that constitutes a bearing that supports an end of the rotary shaft 90 on the opposite side of the compression mechanism 200, and a refrigeration stored in the bottom of the sealed container 70. Machine oil 210e.

  The compression mechanism unit 200 includes a fixed scroll 201 and an orbiting scroll 202, an Oldham ring 209, and a guide frame 215 that are meshed so as to form a compression chamber between at least each plate-like spiral tooth. Prepare.

  A suction pipe 210 a passes through the hermetic container 70 and is press-fitted into the fixed scroll 201 so as to communicate with the plate-like spiral teeth of the fixed scroll 201 from a direction perpendicular to the suction pressure space.

  The outer peripheral surface of the guide frame 215 is fixed to the sealed container 70 by shrink fitting or welding. A high-pressure refrigerant gas discharged from the discharge port of the fixed scroll 201 is provided between the compression mechanism unit 200 and the permanent magnet embedded electric motor 100 by a cutout portion formed by cutting out the outer peripheral portion of the guide frame 215. A flow path leading to the discharge pipe 210b is secured. The notch is provided at a position opposite to the discharge pipe 210b (a position where the phase is approximately 180 ° different).

  Between the compression mechanism part 200 of the hermetic container 70 and the permanent magnet embedded type electric motor 100, a glass terminal 210f for supplying electric power to the permanent magnet embedded type electric motor 100 is fixed by welding.

  Next, the drive circuit 1 of the permanent magnet embedded motor 100 will be described. FIG. 16 is a diagram showing the first embodiment, and is a circuit diagram of the drive circuit 1 of the permanent magnet embedded motor 100. AC power is supplied to the drive circuit 1 from a commercial AC power supply 2 provided outside. The AC voltage supplied from the commercial AC power supply 2 is converted into a DC voltage by the rectifier circuit 3. The DC voltage converted by the rectifier circuit 3 is converted to an AC voltage having a variable voltage and a variable frequency by the inverter main circuit 4 and applied to the permanent magnet embedded motor 100. The permanent magnet embedded motor 100 is driven by AC power of variable frequency supplied from the inverter main circuit 4. The rectifier circuit 3 includes a diode bridge that rectifies the voltage of the commercial AC power supply 2, a chopper circuit that boosts the voltage applied from the commercial AC power supply 2, and a smoothing capacitor that smoothes the rectified DC voltage.

  The inverter main circuit 4 is a three-phase bridge inverter circuit, and the switching portion of the inverter main circuit 4 is silicon carbide as six IGBTs 6a to 6f (insulated gate bipolar transistors) serving as inverter main elements and six flywheel diodes (FRD). SiC-SBDs 7a to 7f (Schottky barrier diodes) using (SiC) are provided. The SiC-SBDs 7a to 7f, which are FRDs, are reverse current prevention means for suppressing the counter electromotive force generated when the IGBTs 6a to 6f turn the current from ON to OFF.

  Here, the IGBTs 6a to 6f and the SiC-SBDs 7a to 7f are IC modules in which each chip is mounted on the same lead frame and molded with epoxy resin and packaged. The IGBTs 6a to 6f may be IGBTs using SiC or GaN (gallium nitride) instead of IGBTs using silicon (Si-IGBT), and MOSFETs using Si, SiC or GaN instead of IGBTs (Metal-Oxide). Other switching elements such as a Semiconductor Field-Effect Transistor may be used.

  Two voltage-dividing resistors 8a and 8b connected in series are provided between the rectifier circuit 3 and the inverter main circuit 4, and the high-voltage DC voltage is reduced by the voltage-dividing circuit using the voltage-dividing resistors 8a and 8b. A DC voltage detector 8 is provided for sampling and holding the electrical signal.

  Current detection elements 30a and 30c for detecting currents flowing in the U-phase winding 20a and the W-phase winding 20c of the permanent magnet embedded type electric motor 100 are provided. As the current detection elements 30a and 30c, a direct current transformer (DCCT), an alternating current transformer (ACCT), or the like is used, and an instantaneous value of a current flowing through the U-phase winding 20a and the W-phase winding 20c is detected.

  The rotor position detection unit 10 calculates the position of the rotor 11 of the permanent magnet embedded motor 100 from the output signals of the current detection elements 30 a and 30 c, and outputs the position information of the rotor 11 to the output voltage calculation unit 9. . Here, the current of two phases of the U-phase winding 20a and the W-phase winding 20c of the embedded permanent magnet electric motor 100 is detected, but the current of three phases including the current of the V-phase winding 20b is also added. May be detected, or currents for two phases of other combinations may be detected.

  The rotor position detection unit 10 may detect the position of the rotor 11 of the embedded permanent magnet electric motor 100 by detecting the terminal voltage of the embedded permanent magnet electric motor 100.

  The position information of the rotor 11 detected by the rotor position detection unit 10 is output to the output voltage calculation unit 9. This output voltage calculation unit 9 is applied to the embedded permanent magnet electric motor 100 based on the command of the target rotational speed N given from the outside of the drive circuit 1 or information on the operating conditions of the device and the position information of the rotor 11. The output voltage of the optimal inverter main circuit 4 is calculated. The output voltage calculation unit 9 outputs the calculated output voltage to the PWM signal generation unit 31. PWM is an abbreviation for Pulse Width Modulation.

  The PWM signal generation unit 31 outputs a PWM signal that becomes the output voltage given from the output voltage calculation unit 9 to the main element drive circuit 4a that drives each of the IGBTs 6a to 6f of the inverter main circuit 4, and the inverter main circuit The four IGBTs 6a to 6f are respectively switched by the main element drive circuit 4a.

  Here, a control method for suppressing the demagnetizing field of the stator 12 will be described. The demagnetizing field of the stator 12 is generated when a large current flows through the winding 20 (the U-phase winding 20a, the V-phase winding 20b, and the W-phase winding 20c) by mistake.

  In the present embodiment, the instantaneous value of the current flowing through the winding 20 is detected, and when the detected instantaneous current value becomes higher than a predetermined current value, the output voltage calculation unit 9 outputs to the PWM signal generation unit 31. Therefore, no large current flows through the winding 20, and demagnetization of the permanent magnet 11c due to the demagnetizing field of the stator 12 can be suppressed. The built-in electric motor 100 can be obtained.

  Here, the wide band gap semiconductor will be described. A wide band gap semiconductor is a generic term for semiconductors having a larger band gap than Si, and SiC used in the SiC-SBDs 7a to 7f is one of the wide band gap semiconductors, in addition to gallium nitride (GaN), There are diamonds. Furthermore, wide band gap semiconductors, particularly SiC, have higher heat resistance temperature, dielectric breakdown strength, and thermal conductivity than Si. Here, although SiC is used for the FRD of the inverter circuit, other wide band gap semiconductors may be used instead of SiC.

  The switching element using SiC realizes a low-loss switching element with a simple configuration and can operate at a higher temperature. Therefore, it can be used near a high-temperature electric motor (or equipment that includes an electric motor), and no cooling fan is required, or airflow fins (heat sinks, etc.) can be reduced in size and weight. It becomes.

  Since switching elements and diode elements formed of such SiC (wide band gap semiconductor) have high voltage resistance and high allowable current density, the switching elements and diode elements can be miniaturized. By using the switching elements and diode elements thus made, it is possible to reduce the size of a semiconductor module incorporating these elements.

  Further, since the heat resistance is high, the heat radiation fins of the heat sink can be downsized and the water cooling part can be air cooled, so that the semiconductor module can be further downsized.

  Furthermore, since the power loss is low, it is possible to increase the efficiency of the switching element and the diode element, and further increase the efficiency of the semiconductor module.

  By setting the switching frequency to a high frequency, the AC voltage generated by the inverter main circuit 4 can output an AC voltage that is closer to a sine wave and has less harmonic components.

  The harmonic component of the AC power applied to the permanent magnet embedded motor 100 becomes a torque ripple of the permanent magnet embedded motor 100, and not only vibration and noise increase, but also motor loss (copper copper) due to the harmonic component current. Loss and iron loss) increase, and there is a problem that efficiency is lowered.

  In the present embodiment, by using SiC for the inverter main circuit 4, the switching frequency can be increased with respect to the inverter main circuit using Si, vibration and noise are low, and the highly efficient permanent magnet embedded. The built-in electric motor 100 can be obtained.

  As an application example of the present invention, there is an embedded permanent magnet motor used in a hermetic compressor.

  DESCRIPTION OF SYMBOLS 1 Drive circuit, 2 Commercial AC power supply, 3 Rectifier circuit, 4 Inverter main circuit, 4a Main element drive circuit, 6a-6f IGBT, 7a-7f SiC-SBD, 8 DC voltage detection part, 8a Voltage dividing resistor, 8b Voltage division Resistance, 9 Output voltage calculation part, 10 Rotor position detection part, 11 Rotor, 11a Rotor core, 11b Air hole part, 11c Permanent magnet, 11d End plate, 11e Rivet, 11f Magnet insertion hole, 11g Shaft hole, 11h Rivet Insertion hole, 11j Shaft hole, 11k Air hole, 11m Rivet insertion hole, 12 Stator, 12a Stator core, 12b Stator slot, 12c Stator notch, 12d Slot opening, 12e Stator tooth, 12f Core Back, 20 winding, 20a U phase winding, 20b V phase winding, 20c W phase winding, 30a Current detection element, 30c Current detection element, 31 PWM signal generation unit, 40 slits, 40a to 40e slits, 60 air gap, 70 airtight container, 71 subframe, 90 rotating shaft, 100 permanent magnet embedded electric motor, 200 compression mechanism unit, 201 fixed scroll, 202 swinging scroll, 209 Oldham ring, 210a suction pipe, 210b discharge pipe, 210e refrigerating machine oil, 210f glass terminal, 215 guide frame, 300 scroll compressor.

Claims (6)

After punching the electromagnetic steel sheet into a predetermined shape, a predetermined number of stator cores are manufactured, a plurality of stator slots formed along the inner periphery of the stator core, and inserted into the stator slots A stator having windings, and
A rotor arranged via a gap on the inner peripheral side of the stator,
The rotor is
After punching the magnetic steel sheet into a predetermined shape, a rotor core manufactured by laminating a predetermined number of sheets,
A plurality of magnet insertion holes formed along the outer periphery of the rotor core;
A permanent magnet inserted into the magnet insertion hole;
A plurality of slits formed on the outer peripheral side of the magnet insertion hole;
An end plate disposed on both end surfaces of the rotor core in the stacking direction; and
Of the plurality of slits, the demagnetization suppression slit disposed on the extension line extending from the circumferential end surface of the permanent magnet to the outer peripheral side of the rotor core is within the width of the single-pole permanent magnet. Compared with other slits formed in the above, a permanent magnet embedded type in which the circumferential width of the demagnetization suppressing slit is wider than the circumferential width of the other slits Electric motor.   The demagnetization suppression slit and the other slit formed within the width of the one-pole permanent magnet are arranged in a direction substantially parallel to the magnetization direction of the permanent magnet and extend toward the outer periphery of the rotor. 2. The embedded permanent magnet electric motor according to claim 1, wherein the electric motor has a shape.   When the minimum dimension between the demagnetization suppression slit and the magnet insertion hole is T1, and the minimum dimension between the demagnetization suppression slit and the outer periphery of the rotor core is T2, T2> T1. The permanent magnet embedded type electric motor according to claim 1, wherein the permanent magnet embedded type electric motor is set.   The end plate has a substantially polygonal shape, and a part of the slit is formed on the outer peripheral side of the linear portion forming the polygon of the end plate, and the slit penetrates in the stacking direction. An embedded permanent magnet electric motor according to any one of claims 1 to 3.   5. The embedded permanent magnet motor according to claim 1, wherein the motor is driven by a drive circuit that uses a device using SiC (silicon carbide) in a switching portion of the inverter main circuit. 6.   6. A hermetic compressor comprising the permanent magnet embedded motor according to claim 1.

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