JP2008125344A - Ac motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an AC motor capable of starting in a direct power-on procedure to a commercial source at the largest up to a 150% load while achieving a high output level, high torque and a small size, and actuating variable speed drive and constant speed drive using an inverter. <P>SOLUTION: Four permanent magnets 1 are mounted to the surface of the middle portion in the axial direction of a rotor R with the same four magnet poles as those in a stator not shown in the diagram so as to enclose the rotor R from the circumference. The permanent magnet 1 has an arcuate section normal to the axial direction of the rotor R. The four permanent magnets 1 mounted to the surface of the rotor R is fitted with some predetermined length in the axial direction of the rotor R so as to enclose a rotor conductor 2 extending in the axial direction of the rotor R simultaneously with a predetermined interpolar distance X1 to the adjoining permanent magnet 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention can start a commercial power supply up to a maximum of 150% load while achieving high efficiency, high output, high torque, miniaturization, and reduction in temperature rise of the AC motor. The present invention relates to an AC motor that can smoothly perform variable speed driving and constant speed driving using an inverter.

  Among AC motors, induction motors rotate by sliding depending on the load, and rotor current flows and torque is generated. Therefore, it is difficult to drive at constant speed in synchronization with the power frequency, and rotor current flows. Therefore, there is a problem that power is lost and temperature rises.

  The brushless DC motor uses the field pole of a rotating permanent magnet, which eliminates the need for a rotor current like an induction motor, improves efficiency, and enables constant speed driving. There is a problem that the encoder and the rotation speed need to be detected, and the configuration of the drive device becomes complicated and expensive.

In order to improve the above problems, the applicants provide an arc-shaped or cylindrical permanent magnet on the rotor surface of an AC motor having a cage shape or a winding shape to constitute a non-salient pole machine. Efficiency, high output, high torque, miniaturization, and reduction in temperature rise can be achieved, and without using a position detection encoder or rotational speed detector such as a brushless DC motor. An inexpensive AC motor that can perform high-speed constant speed driving and variable speed driving has been proposed (see Patent Document 1).
JP 2006-101623 A

  However, the AC motor proposed by the applicants can be started directly into a commercial power source at a light load (up to about 30% of the rated output) at the time of starting up to the synchronous speed. There was a problem that it could not be started directly with a load.

  The present invention is for solving the above-mentioned problems, and the AC motor has a high efficiency of 150% at the maximum while achieving higher efficiency, higher output, higher torque, smaller size, and reduced temperature rise. It is an object of the present invention to provide an AC electric motor that can be started up directly to a load and that can smoothly perform variable speed driving and constant speed driving using an inverter.

  In order to solve the above-mentioned problem, the AC motor according to the first aspect of the present invention comprises a stator core and distributed windings or concentrated windings wound around the stator core in order to form a rotating magnetic field. In an AC electric motor comprising a stator winding and a squirrel cage or a winding conductor, a permanent magnet having the same number of magnetic poles as the stator on the surface of the rotor is rotated. It is characterized by having a fixed length in the axial direction of the child.

  An AC motor according to a second aspect of the present invention is the AC motor according to the first aspect, wherein the permanent magnet is formed in an arc shape in cross section.

  An AC motor according to a third aspect of the present invention is the AC motor according to the first aspect, wherein the permanent magnet is formed in a cylindrical shape in cross section.

  An AC motor according to a fourth aspect of the present invention is the AC motor according to the first aspect, wherein the permanent magnet is formed in a crescent cross section.

  The AC motor of the present invention according to claim 5 is the AC motor according to any one of claims 1 to 5, wherein a cutting portion is formed in advance on a surface of the rotor, and the cutting portion is provided with the cutting portion. It features a permanent magnet.

  An AC motor according to a sixth aspect of the present invention is the AC motor according to any one of the first to fifth aspects, wherein the stator motor is supplied to the stator winding in order to obtain a maximum efficiency of 80% or more. The permanent magnet is magnetized so that the induced electromotive force (counterelectromotive voltage) is 75% to 100% with respect to the applied voltage of the commercial power source.

  An AC motor according to a seventh aspect of the present invention is the AC motor according to any one of the first to sixth aspects, wherein the AC motor is an induction motor.

  An AC motor according to an eighth aspect of the present invention is the AC motor according to any one of the first to sixth aspects, wherein the AC motor is a single-phase induction motor.

  An AC motor according to a ninth aspect of the present invention is the AC motor according to any one of the first to sixth aspects, wherein the AC motor is a three-phase induction motor.

  An AC motor according to a tenth aspect of the present invention is the AC motor according to any one of the first to sixth aspects, wherein the AC motor is a synchronous motor.

According to the AC motor of the present invention, in order to form a rotating magnetic field, a stator core, a stator winding formed of distributed windings or concentrated windings wound around the stator core, and a cage or winding type In an AC electric motor comprising a rotor made of a conductor, a permanent magnet having the same number of magnetic poles as the number of magnetic poles of the stator is provided on the surface of the rotor with a certain length in the axial direction of the rotor. Since it is installed, it can be started directly into the commercial power supply even with a load of 150%, and can be smoothly started up to the synchronous speed in an open loop at any frequency of the power supply frequency or the inverter device.

  In addition, even in synchronous speed, smooth rotation is possible in an open loop, and high efficiency, high output, high torque, miniaturization, and sensorlessness can be achieved, and inexpensive variable speed drive and constant speed drive induction It can be an electric motor.

  Furthermore, the power loss due to the rotor current can be reduced, and the temperature increase can be reduced to achieve a high-efficiency motor that can achieve high efficiency.

  Furthermore, since the rotor conductor has a damper effect that suppresses speed fluctuations accompanying load fluctuations, smooth variable speed driving and constant speed driving can be performed.

  Embodiments of an AC motor according to the present invention will be described below with reference to the drawings of FIGS.

  1 to 3 show an embodiment of a rotor R of an AC motor M according to the present invention, FIG. 1 is a side view of the rotor R, FIG. 2 is a sectional view taken along line AA in FIG. The BB sectional view taken on the line of FIG. 1 is shown. In the figure, symbol R indicates a rotor, and a plurality of cage-shaped rotor conductors 2 extending in the axial direction are arranged at predetermined intervals on the outer peripheral edge of the rotor R. The rotor conductor 2 is disposed in a skewed manner in order to prevent the occurrence of torque fluctuation associated with the rotation angle of the rotor R. Instead of the cage rotor conductor 2, a winding rotor conductor may be used.

  Four permanent magnets 1 having the same number of magnetic poles (four) as the number of magnetic poles of a stator (not shown) are mounted on the surface of the intermediate portion in the axial direction of the rotor R so as to cover the rotor R from the periphery. Yes. The permanent magnet 1 has a circular cross section perpendicular to the axial direction of the rotor R. The four permanent magnets 1 mounted on the surface of the rotor R have a predetermined inter-electrode distance x1 between the adjacent permanent magnets 1 and extend in the axial direction of the rotor R. 2 is mounted with a certain length in the axial direction of the rotor R.

  As a result, the rotor conductor 2 in the intermediate portion in the axial direction of the rotor R is covered with the permanent magnet 1, and the rotor conductors 2 at both ends not covered with the permanent magnet 1 of the rotor R are exposed. ing.

  The stator includes a stator core and a stator winding made of distributed winding or concentrated winding wound around the stator core. Further, the number of magnetic poles of the stator is not limited to four.

  A rotor shaft 3 that rotatably supports the rotor R is provided at the center of the rotor R. Further, short-circuit rings 4 connected to the rotor conductor 2 are provided at both ends of the rotor R, respectively.

  In order to mount the permanent magnet 1 on the surface of the rotor R, the surface of the rotor R is cut in advance by the thickness of the permanent magnet 1 to form a cutting portion 5, and the permanent magnet 1 is formed on the cutting portion 5. Wear. Note that a rotor core in which a mounting portion of the permanent magnet 1 is cut in advance may be manufactured by aluminum die casting, and the permanent magnet 1 may be mounted on the surface of the rotor R.

In this embodiment, the AC motor M is configured as a three-phase induction motor, and has a rated voltage of 200 V, a rated current of 1.05 A, a frequency of 50 Hz, a rated output of 200 W, a rated rotational speed of 1400 min ⁻¹ , a rotor diameter of 66 mm, and a rotation. The number of slots of the child conductor 2 is 40.

  Further, as shown in FIG. 3, the height h1 of the rotor conductor 2 of the rotor R where the permanent magnet 1 is mounted from the periphery is 9.5 mm, and the thickness of the permanent magnet 1 mounted on the surface of the rotor R is as follows. t1 is 3 mm, and the surface of the rotor R is cut by the thickness.

  Further, the distance x1 between the adjacent magnets of the permanent magnet 1 mounted on the surface of the rotor R is 1 mm.

  Furthermore, as shown in FIG. 1, when the axial length of the rotor R of the permanent magnet 1 is 160V, the induced electromotive force (back electromotive voltage) is 78% of the applied voltage 205V of the three-phase power source. , L1 = 35 mm, and the axial lengths of both end portions of the rotor R not covered with the permanent magnet 1 are L2 = 12.5 mm with the same length. Table 2 shows the load test results.

  FIG. 4 shows a configuration of a drive device for the AC motor M having the rotor R of the above-described embodiment. 6 is a supply wiring of a commercial power source (three-phase power source) for directly turning on and starting the AC motor M having the rotor R. A three-phase power supply is directly applied to the AC motor M, and the start-up is performed by directly entering the synchronous speed of the power supply frequency.

  4 is a command frequency of the inverter device 8, and 9 is a power supply line that supplies power to the AC motor M using the inverter device 8 as a power source. The inverter device 8 has a function of a variable voltage and variable frequency conversion device with respect to the command frequency 7, and a function of calculating and displaying the rotational speed.

  When the command frequency 7 is input to the inverter device 8, the inverter device 8 performs V / f control with the command frequency 7 and supplies power to the AC motor M through the power supply line 9. If the AC motor M is started by V / f control and the command frequency 7 is kept constant, constant speed driving can be performed, and if the command frequency 7 is made variable, variable speed driving can be performed.

  Here, when the AC motor M having the rotor R is directly turned on and started, the rotor conductor 2 of the rotor R where the permanent magnet 1 is not covered and the rotor conductor of the portion where the permanent magnet 1 is covered are covered. Inductive current is generated in 2 and induction torque is generated.

  However, in the portion where the permanent magnet 1 of the rotor R is covered, the permanent magnet 1 becomes a load and cannot generate a sufficient induction torque, and the induction torque at the time of starting is exclusively the rotor R. The permanent magnet 1 is generated in a portion that is not covered.

  Then, according to the AC motor M having the rotor R according to this embodiment, the induction torque generated in the portion where the permanent magnet 1 is not covered is directly put into the commercial power source and started even at a load of 150%. The AC motor M can be started up to the synchronous speed of the power supply frequency, and therefore the AC motor M can be started reliably and easily.

  Further, in the AC motor M having the rotor R, when rotating at a commercial frequency by the supply wiring 6 of the three-phase power supply or a constant command frequency 7 of the inverter device 8, a permanent magnet mounted on the surface of the rotor R. 1 can be rotated at a synchronous speed by the magnet torque generated in 1, and reliable constant speed driving can be performed.

  Further, when the speed fluctuates due to load fluctuation, an induced current is generated in the rotor conductor 2 to generate an induced torque, and this induced torque acts as a damper effect that suppresses the speed fluctuation. Smooth driving can be performed even at a constant speed.

  Note that the permanent magnet 1 mounted on the rotor R may have a cylindrical cross-sectional shape perpendicular to the axial direction of the rotor R as shown in FIG. In this case, it goes without saying that even if the permanent magnet 1 is formed in a cylindrical shape, the permanent magnet 1 is magnetized to have the same number of magnetic poles as that of the stator in the circumferential direction of the cylinder. If formed in this way, the number of parts of the permanent magnet 1 can be reduced from four to one.

  Further, as shown in FIG. 6, the permanent magnet 1 may have a crescent-shaped cross section perpendicular to the axial direction of the rotor R. If formed in this way, it is possible to prevent the occurrence of torque fluctuations associated with the rotation angle of the rotor R.

  Further, as shown in FIG. 7 to FIG. 9, the permanent magnet 1 is mounted with a length of L3 only on one side in the axial direction of the rotor R, and the length of L4 is mounted on the other side of the rotor R. The rotor conductor 2 may be exposed. The permanent magnet 1 may have any of the above-described arc shape, cylindrical shape, and crescent shape.

  Furthermore, as shown in FIGS. 10 to 12, the permanent magnet 1 is mounted on both axial end portions of the rotor R, and the rotor conductor 2 in the center portion of the rotor R is exposed. Also good. In this case, the axial lengths of the permanent magnets 1 respectively attached to both end portions of the rotor R are the same as L6. The permanent magnet 1 may have any of the above-described arc shape, cylindrical shape, and crescent shape.

  As described above, the inventors of the present invention can not only reliably and easily start the AC motor, but also the efficiency after entering the synchronous operation, as described above. I found it very good. Hereinafter, the load test results will be described with reference to Tables 1 to 3.

  Table 1 shows data of a conventional AC motor, and shows a load test result after starting a 200 W induction motor directly into a three-phase power source (200 V, 50 Hz). Each characteristic value of the stator current of 1.05A in Table 1 indicates a value obtained by proportionally calculating the values of the characteristics of the stator currents of 1.02A and 1.12A. According to Table 1, the maximum efficiency is 72%, the rated current is 200 W, the stator current is 1.057 A, the slip is 0.06, and the constant speed drive is impossible. The torque is 1.34 N · m at a rated current of 1.05 A.

  On the other hand, in Table 2, the induced electromotive force (back electromotive force) is 160V, which is 78% with respect to the applied voltage 205V of the three-phase power source. Table 2 shows the AC of a permanent magnet with a permanent magnet 1 as shown in FIG. 1 (L1 = 35 mm, L2 = 12.5 mm) on the rotor surface of a 200 W induction motor used in the test of Table 1. The data of the motor M are shown, and the load test result at the time of constant speed driving at the synchronous speed of the power frequency is shown by starting the induction motor with a permanent magnet directly into the three-phase power source (200 V, 50 Hz). Each characteristic value of the stator current of 1.05 A in Table 2 indicates a value obtained by proportionally calculating the values of the characteristics of the stator currents of 0.95 A and 1.1 A.

  From Table 2, the maximum efficiency is 82%, which is 10% higher than the maximum efficiency of the conventional induction motor shown in Table 1.

Further, at a rated output of 200 W, the stator current is about 0.77 A, which is reduced to about 73% of the rated current of 1.05 A. In the proportional calculation when the rated current is 1.05 A, the output is about 272 W, which is about 1.36 times the rated output 200 W. Further, the rotational speed is kept at a constant value of the synchronous speed 1500 min ⁻¹ even at about 2.4 times the rated output. The torque was 1.73 N · m (proportional calculation) at a rated current of 1.05 A, and it was found that the torque was increased by 0.39 N · m from the conventional induction motor shown in Table 1 at the same rated current.

  Regarding the temperature rise, in the induction motor that is a conventional AC motor used in the load test of Table 1, when the torque is 1.27 N · m and an output of about 188 W is loaded for 60 minutes continuously, the room temperature is 26.3. At 0 ° C., the output side of the motor case is 61.6 ° C., the center portion of the motor case is 71.8 ° C., and the rear portion of the motor case is 64.0 ° C., showing no saturation.

  On the other hand, in the induction motor with a permanent magnet used in the load test shown in Table 2, when the torque is 1.28 N · m and an output of about 201 W is loaded by continuous operation for 60 minutes, the motor case at room temperature of 21.2 ° C. The output side is 46.5 ° C., the central portion of the motor case is 50.8 ° C., and the rear portion of the motor case is 48.4 ° C., indicating saturation.

  From this result, in the induction motor with a permanent magnet of the present invention, considering the room temperature, 10 ° C. on the output side of the case, 15.9 ° C. at the center of the case, 10.5 ° C. at the rear of the case, compared to the conventional induction motor It was found that the temperature was decreasing.

  FIG. 13 shows the V curve of the stator terminal voltage (applied voltage) and the stator current for a constant output when the applied voltage supplied to the stator winding of the AC motor M is varied. In this V curve, it is known that when the applied voltage is equal to the induced electromotive force (counterelectromotive voltage), the stator current is minimized and the power factor is 100%.

  The permanent magnet 1 mounted on the surface of the rotor R of the AC motor M of the present invention has the same induced electromotive force (counterelectromotive voltage) as the applied voltage of the commercial power supplied to the stator winding of the AC motor M. When magnetized in this way, the stator current becomes minimum at the applied voltage of the commercial power supply, and the power factor becomes 100%.

  Table 3 shows that the permanent magnet 1 mounted on the rotor surface of the 200 W induction motor used in the test of Table 1 has an induced electromotive force that is approximately 100% of the applied voltage of the commercial power source. The load test result when magnetized so as to be (back electromotive voltage) is shown. Each characteristic value of the stator current of 1.05 A in Table 3 indicates a value obtained by proportionally calculating the value of each characteristic of the stator current of 1 A and 1.1 A.

  In this case, the applied voltage supplied to the stator winding is 206V, the induced electromotive force (counterelectromotive voltage) is 199V (97% with respect to the applied voltage), and the rotor surface R is shown in FIG. The permanent magnet 1 is attached to the head, and L1 = 42 mm and L2 = 9 mm. A load test result is a thing at the time of 50Hz drive by an inverter.

From the load test results in Table 3, it was found that the stator current (rated value 1.05 A) was 1 A, the torque was 2 N · m, the output was about 314 W, and the efficiency was 87.3%, which was the maximum efficiency. It was found that even when the stator current was 2.2 A, the synchronous speed was maintained at a constant value of 1500 min ⁻¹ , the torque was 4 N · m, the output was 628.5 W, and approximately three times the rated output. . The efficiency at this time is 79.6%.

  Table 4 shows that the induced electromotive force <counter electromotive voltage> is 78% (Table 2) and 83% of the applied voltage of the commercial power supply (1.05A of the rated value from the load test result after direct input to the commercial power supply and starting). Each characteristic value obtained by proportional calculation is shown for 97), 97% (Table 3), and 104.3% (each characteristic obtained by proportional calculation for the rated value of 1.05A from the load test result when driving the inverter) In the case of the stator current (rated value) in the case of 10.5 A, each characteristic value obtained by proportional calculation and each power factor (calculated value from each characteristic value obtained by proportional calculation) are further included. The characteristic values are compared and shown. Further, the characteristic values of the conventional induction motor shown in Table 1 are also shown.

  As shown in Table 4, each characteristic value increases with an increase in the ratio of the induced electromotive force (counterelectromotive voltage) to the applied voltage of the commercial power supply, and the induced power (counterelectromotive voltage) is approximately 100% of the imprint voltage. The values of torque, output, efficiency and power factor characteristics when magnetized are most improved. Each characteristic value corresponding to an induced electromotive force of 100% or more is smaller than each characteristic value corresponding to an induced electromotive force of 100%.

  The above-described embodiments are merely representative examples of the present invention, and the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. .

  That is, although the three-phase induction motor has been described as an example in the embodiment, it is needless to say that the present invention can be applied not only to a three-phase AC motor but also to a single-phase induction motor, a two-phase induction motor, and a multi-phase induction motor. Needless to say, commercial power supplies are not limited to three-phase power supplies.

It is a sectional side view which shows the rotor of the alternating current motor which concerns on one Embodiment of this invention. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is a block diagram which shows the drive device of the alternating current motor which concerns on this invention. It is sectional drawing which shows the modification of the permanent magnet shown in FIG. It is sectional drawing which shows the other modification of the permanent magnet shown in FIG. It is a sectional side view which shows the rotor of the alternating current motor which concerns on other embodiment of this invention. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is a sectional side view which shows the rotor of the alternating current motor which concerns on other embodiment of this invention. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is a figure which shows the relationship between the stator terminal voltage at the time of varying the applied voltage supplied to the stator winding | coil of an alternating current motor, and a stator electric current.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Permanent magnet 2 Rotor conductor 3 Rotor shaft 4 Short ring 5 Cutting part 6 Three-phase power supply wiring 7 Command frequency of inverter device 8 Inverter device 9 Power supply line R Rotor M AC motor

Claims (10)

In order to form a rotating magnetic field, a stator core, a stator winding made up of distributed windings or concentrated windings wound around the stator core, and a rotor made up of a cage or a wound conductor are provided. In the AC motor
An AC electric motor, wherein a permanent magnet having the same number of magnetic poles as that of the stator is mounted on the surface of the rotor so as to have a certain length in the axial direction of the rotor.   The AC motor according to claim 1, wherein the permanent magnet has an arcuate cross section.   The AC motor according to claim 1, wherein the permanent magnet has a cylindrical cross section.   2. The AC motor according to claim 1, wherein the permanent magnet is formed in a crescent cross section.   5. The AC motor according to claim 1, wherein a cutting portion is formed in advance on a surface of the rotor, and the permanent magnet is attached to the cutting portion.   The permanent magnet is magnetized so that an induced electromotive force (counterelectromotive voltage) is 75% to 100% with respect to an applied voltage of a commercial power source supplied to the stator winding. The AC motor according to any one of claims 1 to 5.   The AC motor according to any one of claims 1 to 6, wherein the AC motor is an induction motor.   The AC motor according to any one of claims 1 to 6, wherein the AC motor is a single-phase induction motor.   The AC motor according to any one of claims 1 to 6, wherein the AC motor is a three-phase induction motor.   The AC motor according to any one of claims 1 to 6, wherein the AC motor is a synchronous motor.

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