JP3595973B2 - Brushless DC motor and washing machine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a brushless DC (direct current) motor and a washing machine equipped with the motor.
[0002]
[Prior art]
A conventional general washing machine uses a single-phase induction motor as a motor, and the single-phase induction motor rotates a pulsator and a dehydration tub at a rotation speed determined by a commercial power frequency. In order to adjust to the desired number of revolutions and torque, reduction gears, pulleys and belts are used, and when the pulsator is operated at a low speed during the washing and rinsing steps, and when the dehydration tank is operated at a high speed during the dehydration step. Regarding the switching of the number of rotations, two types of rotations are created by switching using a clutch.
[0003]
In addition, an ON / OFF method, a phase control method, and the like have been proposed as methods for varying the number of revolutions. However, there are drawbacks such as a large noise and vibration and a narrow variable width. A washing machine of an inverter control type using a phase motor has been proposed.
[0004]
In this inverter control system, a three-phase motor (induction motor or brushless DC motor) is used instead of the conventionally used single-phase induction motor, and the motor drive unit by the inverter device has a phase shift of 120 degrees for the motor. It is necessary to apply an alternating current. The inverter device has a three-phase full-wave bridge configuration using six switching elements such as a power transistor and an IGBT (Insulated Gate Bipolar Transistor) and is connected to each phase (U-phase, V-phase, W-phase) of the three-phase motor. Have been.
[0005]
Above all, at present, brushless DC motors are generally used more often. This is because the brushless DC motor has higher efficiency than conventional single-phase induction motors and three-phase induction motors, and is advantageous in terms of energy saving and miniaturization.
[0006]
This brushless DC motor generally includes a three-phase armature winding, a rotor formed of a permanent magnet, and a rotor position detecting means such as a Hall element for detecting the rotational position of the rotor. FIG. 13 shows the structure of the rotor of the brushless DC motor. 41 is a stator. 43 is a rotor. Reference numeral 44 denotes a magnet unit provided on the outer peripheral portion of the rotor 43.
[0007]
Unlike an induction motor, in a brushless DC motor, a three-phase alternating current is generated based on a rotor position signal synchronized with the rotor position detected by the rotor position detection means, and the inverter device converts this into a three-phase armature winding. The brushless DC motor is supplied to rotate the brushless DC motor.
[0008]
Recently, a direct drive system in which a pulsator and a dewatering tub are directly driven by a brushless motor instead of the conventional pulley and belt system has been proposed.
[0009]
[Problems to be solved by the invention]
When a brushless DC motor is applied to a direct drive system, a larger torque is required as compared with a conventional belt system using a pulley, a belt, or the like. In other words, in the conventional belt system, the driving force of the motor is transmitted to the pulsator and dehydration tub at a reduced speed using pulleys and belts. Therefore, the motor torque can be reduced. On the other hand, in the case of the direct drive system, the torque of the motor is directly converted and acts on the pulsator or the dewatering tub without being converted. For example, when the reduction ratio is about twice as high with a pulley and about eight times as low with a gear via a belt, to achieve this by the direct drive method, the torque of the motor is about 15 times that of the conventional method. Will be needed.
[0010]
In the structure of the conventional brushless DC motor rotor as shown in FIG. 13, since the motor capacity is increased in order to increase the torque, the magnet must be used on the entire surface of the rotor, and the shape of the magnet becomes large. , Cost was up. Also, the shape of the motor has become large, and the weight of the washing machine body has also been heavy.
[0011]
An object of the present invention is to provide a brushless DC motor capable of obtaining a large torque with a small size, and a washing machine which achieves low noise and low vibration by using such a brushless DC motor. .
[0012]
[Means for Solving the Problems]
To solve the above problems,In the lightIs a brushless DC motor composed of a rotor and a stator, wherein the rotor has magnet parts and magnetic material parts arranged alternately in a radial pattern.The stator has a plurality of teeth, and windings of the same phase are wound around two adjacent teeth so that the winding directions are opposite to each other..Further, in another configuration of the present invention, in a brushless DC motor including a rotor and a stator having a plurality of teeth, in the rotor, the magnets and the magnetic material are alternately arranged in a radial pattern, In the stator, the windings of the same phase are wound around two adjacent teeth so that the winding directions are opposite to each other, so that the phases in which the magnet torque and the reluctance torque work are shifted.
[0013]
According to such a configuration, the brushless DC motor is arranged so that the magnet portion and the magnetic material portion are alternately radially arranged, so that the reluctance generated in the magnetic material portion is added to the magnet torque generated by the magnet provided on the rotor. Torque (electromagnetic force that works to reduce magnetic resistance) can be used. Therefore, the motor torque can be increased with the same rotor shape.In addition, since the windings of the same phase are wound around the two adjacent teeth so that the winding directions are different, the torque acting from the two teeth of the same phase is dispersed.
[0014]
Also,the aboveIn the brushless DC motor, the magnet portion and the magnetic material portion are fixed by a nonmagnetic material.May be.
[0015]
According to such a configuration, since the magnet portion and the magnetic material portion are fixed by the nonmagnetic material member, the scattering of the magnet portion and the magnetic material portion is prevented. Further, since this member is a non-magnetic material, it does not disturb the magnetic flux from the stator winding.
[0016]
Also,the aboveIn a brushless DC motor, the magnet part is embedded in the magnetic material part.May be.
[0017]
According to such a configuration, since the magnet portion is embedded in the magnetic material portion, it is easy for the rotor to hold the magnet portion, and scattering of the magnet portion due to centrifugal force during rotation of the rotor is prevented. .
[0018]
Also,the aboveIn the brushless DC motor, the magnet portion and the magnetic material portion have a skew structure twisted in the axial direction of the rotor.May be.
[0019]
According to such a configuration, since the rotor has a skew structure in which the rotor is twisted in the axial direction, the timing at which the magnet torque and the reluctance torque act are dispersed. This reduces torque ripple and suppresses vibration.
[0020]
Also,the aboveIn the brushless DC motor, the rotor is formed by disposing the magnet portion and the magnetic material portion on a disk-shaped holding plate along an outer periphery on the holding plate.May be.
[0021]
According to such a configuration, since a gap is provided inside the rotor, when a brushless DC motor is used in a washing machine or the like, components such as a clutch mechanism can be arranged in the gap. Thereby, the thickness of the motor can be reduced.
[0022]
Also,the aboveIn the brushless DC motor, the rotor has a cantilever structure in which one end is supported by a shaft.Good.
[0023]
According to such a configuration, since the shaft has a cantilever structure attached to only one side, it is only necessary to provide a bearing portion for supporting the rotor on one side of the motor, and the thickness of the motor can be reduced.
[0026]
According to an eighth aspect of the present invention, in the brushless DC motor according to any one of the first to seventh aspects, the rotor position is detected based on the position and the magnetization direction of the magnet unit, and a rotor position signal is output. At least one rotor position detecting means is provided at a position where the phase of the waveform of the rotor position signal and the phase of the waveform of the induced voltage generated when the brushless DC motor rotates.
[0027]
According to such a configuration, the position of the rotor position detecting means can be clarified because the rotor position detecting means may be arranged so that the phase of the waveform of the rotor position signal and the phase of the waveform of the induced voltage match.
[0028]
According to a ninth aspect of the present invention, in a washing machine including a brushless DC motor that rotationally drives a pulsator and a dewatering tub, and a motor drive unit that variably controls the number of revolutions of the brushless DC motor, the brushless DC motor is The brushless DC motor according to claim 8 is provided.
[0029]
According to such a configuration, since the brushless motor according to the eighth aspect which can obtain a large torque is used, the noise and vibration of the washing machine are reduced. Also, it can respond to variable speed operation.
[0030]
According to a tenth aspect of the present invention, in the washing machine according to the ninth aspect, the motor driving unit applies a voltage having a waveform that matches the waveform of the rotor position signal to the brushless DC motor.
[0031]
According to such a configuration, the motor drive unit can drive the brushless DC motor by using the magnet torque most efficiently by supplying a voltage having a waveform that matches the waveform of the rotor position signal.
[0032]
According to an eleventh aspect of the present invention, in the washing machine according to the ninth aspect, the motor driving unit applies a voltage having a waveform having a phase advanced from the waveform of the rotor position signal to the brushless DC motor. .
[0033]
According to such a configuration, since the output voltage waveform is output at a phase advanced from the signal detected by the rotor position detection means, the reluctance torque is efficiently used where the influence of the induced voltage generated in the winding during high-speed rotation does not increase. And facilitates high-speed rotation of the motor.
[0034]
According to a twelfth aspect of the present invention, in the washing machine according to the ninth aspect, when the brushless DC motor is started, the motor driving unit is configured to perform the operation based on the plurality of rotor position signals obtained by the plurality of rotor position detection units. To start the brushless DC motor, and after the start, drives the brushless DC motor based on the rotor position signal obtained by only one of the rotor position detecting means.
[0035]
According to such a configuration, even when the brushless DC motor is stopped, the absolute position of the rotor can be detected from a plurality of rotor position signals obtained by the plurality of rotor position detecting means. Is possible. After startup, the motor can be driven by detecting the rotor position by using only one of the rotor position detecting means so that the fluctuation of the rotor position signal due to the fluctuation of the mounting position of the rotor position detecting means does not matter. .
[0036]
According to a thirteenth aspect of the present invention, in the washing machine according to the ninth aspect, there is provided a storage device for storing a correction value for correcting a deviation between the waveform of the rotor position signal and the waveform of the induced voltage.
[0037]
According to such a configuration, there is a case where the phase between the rotor position signal and the induced voltage waveform actually shifts. However, since the correction value for correcting the shift is stored in the storage device, the brushless DC motor uses this correction value. The position of the rotor can be accurately grasped by the correction value.
[0038]
According to a fourteenth aspect of the present invention, in the washing machine according to the ninth aspect, there is provided an induced voltage detecting means for detecting the induced voltage, and the motor drive unit is configured to output the waveform of the rotor position signal and the waveform of the induced voltage. The brushless DC motor is driven by correcting the phase shift of the brushless DC motor in real time.
[0039]
According to such a configuration, the washing machine can correct the difference between the rotor position signal and the induced voltage waveform signal in real time by the induced voltage waveform detection means, and thus can accurately detect the rotor position.
[0040]
According to a fifteenth aspect of the present invention, in the washing machine according to the ninth aspect, the washing machine according to the ninth aspect further includes an induced voltage detecting unit configured to detect the induced voltage, and the motor driving unit outputs the rotor position signal when the brushless DC motor is started. Based on the induced voltage, the brushless DC motor is driven based on the induced voltage.
[0041]
According to such a configuration, the plurality of rotor position detection means can detect the absolute position of the rotor from the N / S poles of the plurality of magnets in the rotor even when the motor is at the stop position. Then, the motor can be started from the rotational position thus detected. Then, after starting, the position of the motor can be accurately detected by the induced voltage generated by the rotation of the motor.
[0042]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments according to the present invention will be described with reference to the drawings. First, a schematic configuration of a washing machine will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a washing machine main body, and 2 denotes a dehydration tub which also serves as a washing tub for washing and dehydrating laundry. This dehydration tub is provided inside a water tub 3. The water tank 3 is elastically suspended from the washing machine main body 1 by a suspension 4. The pulsator 5 is arranged at a fixed distance from the bottom of the dewatering tub 2 by a rotating shaft. A clutch mechanism 6 is provided as means for switching the rotation of the pulsator 5 and the spin tub 2. A brushless DC motor 7 is directly connected to the clutch mechanism 6. In this case, the driving method of the motor is the direct drive method.
[0043]
The motor drive unit for driving the motor 7 includes an inverter unit 8 having six switching elements in a three-phase full-wave bridge configuration, as will be described later, and a control unit 9 including a microcomputer or the like. The control unit 9 switches the clutch mechanism unit 6 according to each process such as washing, rinsing, and dehydration (however, the switching system is not shown), and also changes the rotation speed of the pulsator 5 and the dehydration tub 2. Let me. Further, a rotor position detecting means 10 for detecting the position of the rotor required for the drive control of the motor 7 is provided based on the position of the magnet portion of the rotor such as a Hall IC and the direction of magnetization. Reference numeral 11 denotes a storage device used in a tenth embodiment described later.
[0044]
Next, the internal configuration of the motor drive unit will be described in detail with reference to FIG. The AC supplied from the commercial power supply 20 is converted into DC by the rectifier 21. The DC rectified by the rectifier 21 is smoothed by the smoothing capacitor 22 and converted to a complete DC. This direct current is converted into a three-phase alternating current by the inverter unit 8 and applied to the brushless DC motor 7.
[0045]
In the inverter section 8, six NPN transistors Q1 to Q6 are connected as switching elements to three pairs of arms corresponding to three phases. Freewheeling diodes D1 to D6 are connected in parallel to the six switching elements, respectively, and three connection points a, b, and c of the upper arm and the lower arm are connected to the three-phase electric motor of the brushless DC motor 7. Child windings (U-phase, V-phase, W-phase).
[0046]
The six switching elements are each driven by the drive circuit 23. The drive signal is a drive signal corresponding to the rotor position, which is obtained by obtaining signals from rotor position detection means 10a, 10b, and 10c such as three Hall elements for detecting the rotor position of the brushless DC motor 7 through a rotor position detection circuit 24. Is created by the control unit 9.
[0047]
Next, the structure of the brushless DC motor 7 of the present invention will be described. The present invention is characterized in that reluctance torque can be used in addition to the conventional magnet torque. Therefore, the magnet torque and the reluctance torque will be described first. FIG. 3A shows the structure of a brushless DC motor that rotates only by magnet torque. As shown in FIG. 3A, the tip of the tooth portion 80 of the stator 41 becomes an N-pole or an S-pole depending on the direction of a current flowing through a winding (not shown) wound around the tooth portion 80 of the stator 41. A magnet force F1 is generated to attract the S and N poles of the magnet appearing on the outer peripheral surface of the rotor 43, and the magnet force F1 becomes a magnet torque for rotating the rotor 43. On the other hand, FIG. 3C shows the structure of a motor that rotates only with reluctance torque. When the winding wound around the tooth portion 80 of the stator 41 is excited, the stator tooth portion 80 becomes an electromagnet, and a reluctance force F3 is generated, which attracts the salient pole portion 95 of the rotor 43 made of a magnetic material. It becomes a reluctance torque for rotating 43.
[0048]
FIG. 3B is a structure of a brushless DC motor showing features of the present invention for obtaining both magnet torque and reluctance torque. As shown in FIG. 3B, magnet portions 91 and magnetic material portions 90 are alternately arranged inside the rotor 43. Depending on the direction of the current flowing through the windings of the stator 41, the teeth 80 of the stator 41 become N-poles or S-poles. F2 is generated, and the force F2 becomes a torque for rotating the rotor 43. As described above, the brushless DC motor of the present invention can use both the magnet torque and the reluctance torque, so that the torque can be increased as compared with the conventional brushless DC motor.
[0049]
<First embodiment>
FIG. 4 shows a structure of a brushless DC motor 7 according to the first embodiment of the present invention, which rotates a rotor with magnet torque and reluctance torque. The windings 42 are respectively applied to the tooth portions 80 of the stator 41. The connection / winding direction of the winding 42 differs depending on the number of phases and the number of poles of the motor 7. Note that FIG. 4 shows only the winding 42 wound around one tooth 80, and the winding wound around the other tooth 80 is not shown. The rotor 43 is configured such that magnet portions 44 and magnetic material portions 45 such as silicon steel plates are alternately arranged on the outer peripheral surface of the rotor to utilize magnet torque and reluctance torque. Since the magnet portions 44 and the magnetic material portions 45 are alternately arranged in a radial pattern as described above, reluctance torque is obtained in the magnet torque as described above. The torque increases. Therefore, the motor 7 is small and lightweight.
[0050]
<Second embodiment>
Next, a second embodiment of the present invention will be described. FIGS. 5A and 5B are structural views of the rotor of the brushless DC motor 7 of the second embodiment (see FIG. 1). FIG. 5A is a plan sectional view, and FIG. The magnet portions 44 and the magnetic material portions 45 are alternately arranged on the disk-shaped holding plate 46b along the outer periphery of the holding plate 46b, and are fixed with screws, adhesives, or the like. In this state, the magnet portion 44 and the magnetic material portion 45 are separated from each other. Therefore, a holding ring 46a for holding these on the upper surface of the rotor is provided. The holding ring 46a fixes the magnet part 44 and the magnetic material part 45 with a screw, an adhesive or the like. At this time, the material of the retaining ring 46a is a non-magnetic material so as not to disturb the magnetic field of the rotor. Reference numeral 47 denotes a rotor shaft, which is fixed on the central axis of the holding plate 46b and integrated therewith.
[0051]
Thus, a gap 110 can be provided inside the rotor, and the clutch mechanism 6 (see FIG. 1) and the like can be disposed in the gap 110. Therefore, the thickness of the motor 7 can be reduced. As described above, the torque can be output even when the air gap 110 is provided inside the rotor because the magnet portions 44 and the magnetic material portions 45 are alternately arranged so that the magnet torque and the reluctance torque can be used. This is because it is not necessary to pass the magnetic flux from the stator winding to the inside of the rotor.
[0052]
<Third embodiment>
Next, a third embodiment of the present invention will be described. In the brushless DC motor according to the first embodiment (see FIG. 4), the magnet portions 44 and the magnetic material portions 45 are alternately exposed on the outer peripheral surface of the rotor 43. However, as shown in FIG. It may be at a position retracted from the outer peripheral surface of the material part 43. However, the thickness d of the magnetic material part 45 in the magnet part 44 needs to be about 0.5 mm to several mm.
[0053]
The rotor 43 having such a structure is manufactured, for example, by making a plurality of holes at positions retreated inward from the outer peripheral surface of the cylindrical magnetic material portion 43 and embedding a magnet in the holes. Since the magnet portion 44 is embedded in the magnetic material portion 45 of the rotor 43 in this manner, the magnet portion 44 is easily held, and the magnet portion 44 is not scattered by centrifugal force even when the rotor 43 rotates. Has become. Further, since the magnet portion 44 can be fixed at an accurate position, occurrence of torque ripple can be prevented, and noise and vibration can be reduced. Further, since the outer peripheral surface of the rotor 43 is covered with the magnetic material portion 45, the roundness of the outer peripheral surface is also improved. Thereby, the windage generated when the rotor 43 rotates is reduced, so that the rotation speed and the torque are also improved.
[0054]
<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described. In the first embodiment (FIG. 4), the magnet portion 44 has a shape parallel to the thickness direction. However, in order to reduce the cogging torque of the motor 7, the magnet portion 44 is shown in FIG. As described above, the magnet portion 44 is provided at a predetermined angle with respect to the thickness direction T. As a result, the rotor 43 has a skew structure in which the magnet portion 44 and the magnetic material portion 45 are twisted in the direction of the same axis 47 as the thickness direction T, so that the timings at which the magnet torque and the reluctance torque act are dispersed. Thereby, torque ripple is reduced in the motor 7 and vibration is also suppressed. FIG. 7A is a plan sectional view of the rotor 43 of the fourth embodiment.
[0055]
<Fifth embodiment>
Next, a fifth embodiment of the present invention will be described. FIG. 8 is a rotor structure diagram of a brushless DC motor 7 according to the fifth embodiment. The magnet portion 44 and the magnetic material portion 45 are alternately arranged on the disk-shaped holding plate 46 along the outer periphery of the holding plate 46, and a gap is provided inside the rotor 43. ing. Then, the holding plate 46 on the bottom surface of the rotor is fixed to the shaft 47. As a result, the rotor 43 has a cantilever structure supported only at one end by the shaft 47. It is to be noted that a bearing portion for coupling with the shaft 47 can be omitted at the lower portion of the rotor, and the bearing portion 48 is provided at a position away from the rotor 43, and the shaft 47 need only be supported by the bearing portion 48. . Therefore, a space for parts for supporting the rotor 43 is not required under the rotor, and the thickness of the entire motor can be reduced.
[0056]
Further, by disposing the clutch mechanism 6 (see FIG. 1) and the like inside the rotor 43, the thickness of the entire motor can be further reduced. When the thickness of the motor 7 is reduced, the lower surface of the spin tub 2 (see FIG. 1) of the washing machine can be lowered, and the spin tub 2 can be enlarged without increasing the height of the main body of the washing machine. As a result, the user can easily take out the laundry and increase the capacity.
[0057]
<Sixth embodiment>
Next, a sixth embodiment of the present invention will be described. FIG. 9 is a rotor structure diagram of a brushless DC motor according to a sixth embodiment. Although the stator winding is not particularly described in the first embodiment (FIG. 4), in the sixth embodiment, two adjacent teeth 80 of the stator 41 have the same phase. The (a-phase, b-phase, and c-phase) windings are wound so that the winding directions are different (reverse). As a result, the magnet torque and the reluctance torque do not work at the same time but work out of phase, so that the torque peaks are dispersed and the torque ripple is reduced.
[0058]
<Seventh embodiment>
Next, a seventh embodiment of the present invention will be described. In order for the brushless DC motor 7 (see FIG. 1) to operate normally, it is generally necessary to accurately detect the magnet position of the rotor. In the case of a conventional brushless DC motor, usually, a rotor position detecting means 10 (see FIG. 1) such as a Hall IC is attached so as to detect a position where the magnet torque is maximized. In the case of a motor that can use magnet torque and reluctance torque as described above, the position of the rotor position detecting means cannot be determined only by the maximum position of the magnet torque because there is a magnetic material portion between the magnets. For this reason, the detection position is determined based on the induced voltage waveform generated when the rotor is actually rotated.
[0059]
The mounting position of the rotor position detecting means 10 in the case of the three-phase brushless DC motor 7 will be described with reference to FIG. First, the rotor position detection means 10 such as a Hall IC is attached to each rotor position detection means 10 so that the rotor position signals are three-phase signals shifted by 120 degrees, such as Ha, Hb and Hc. The position is determined.
[0060]
In addition, since the induced voltage generated in the winding of the stator by the rotation of the magnet of the rotor is also of three phases, the sinusoidal waveform is shifted by 120 degrees like Va, Vb, and Vc. At this time, the position of the a-phase rotor position detecting means 10 is determined such that the position of the rising edge 50 of Ha coincides with the zero cross point 51 in the positive direction of Va. Similarly, the positions of the b-phase and c-phase rotor position detecting means are such that the rising edge positions 52 and 54 coincide with the positive zero-cross points 53 and 55 of Vb and Vc, respectively. The position of the position detecting means 10 is determined.
[0061]
Further, even when the rotation direction of the rotor is the reverse direction, the position of the rotor position detection means 10 is determined so that the falling edge coincides with the zero-cross point in the negative direction. Since the position of the rotor position detecting means 10 is clear as described above, the position of the rotor that controls the motor 7 is accurately detected. Further, since the rotor position signals Ha, Hb, Hc obtained from the rotor position detecting means 10 are in phase with the induced voltages Va, Vb, Vc, respectively, the magnet torque and the reluctance torque are determined based on the signals Ha, Hb, Hc. The control for effectively extracting the data becomes easy.
[0062]
<Eighth embodiment>
Next, an eighth embodiment of the present invention will be described. In the washing machine, the load characteristics of the motor 7 (see FIG. 1) are different between the washing / rinsing step and the dehydrating step. The load characteristics at the time of washing and rinsing are usually characterized by a low rotation speed and a large load. On the other hand, the load characteristics at the time of dehydration are characterized in that the number of rotations is high and the load is small. For example, in the case of the direct drive system, the motor 7 is directly connected to the pulsator 5 (see FIG. 1) at the time of washing and rinsing by switching the clutch, so that the rotational speed is about several tens to 200 rpm and the load torque is about 200 to 300 kgfcm. ing. On the other hand, at the time of spin-drying, the motor 7 is directly connected to the spin-drying tub 2 (see FIG. 1), so that the number of rotations reaches a maximum of about 100 rpm. The load torque at this time is about 30 kgfcm.
[0063]
As described above, since large torque is required at low speed during washing and rinsing, the washing machine mainly uses magnet torque that is likely to produce large torque at low speed. In order to effectively use the magnet torque, an application voltage INVa synchronized with the rotor position signal Ha may be supplied to the brushless DC motor 7, as shown in FIG. Therefore, at the time of startup, control is performed at a timing that matches the rotor position signal Ha, and the timing is shifted so that the reluctance torque is used a little when the rotation speed increases.
[0064]
On the other hand, it is necessary to rotate at high speed during dehydration. When the brushless DC motor 7 rotates at a high speed, a back electromotive voltage is generated by the power generation action of the motor 7 and the induced voltage increases, so that the voltage applied from the inverter unit 8 does not enter the brushless DC motor 7. Therefore, it is difficult to control the high-speed rotation.
[0065]
Therefore, the brushless DC motor 7 can use not only the magnet torque but also the reluctance torque. Therefore, the magnet torque that generates the back electromotive voltage is not used at the time of high-speed rotation. To facilitate high-speed rotation. In order to increase the ratio of using the reluctance torque, as shown in FIG. 12, an advance angle (field weakening) control for outputting the applied voltage INVa at a phase advanced from the energization timing obtained from the rotor position signal Ha is performed. As a result, the induced voltage waveform Va decreases. That is, since the back electromotive voltage is reduced, high-speed rotation is facilitated.
[0066]
<Ninth embodiment>
Next, a ninth embodiment of the present invention will be described. In the eighth embodiment, the motor 7 (see FIG. 1) is controlled by the rotor position detecting means 10 (see FIG. 1) by a plurality of rotor position detecting means 10 such as Hall ICs. If the mounting position of the means 10 varies, the rotor position signals Ha, Hb, Hc of each phase as shown in FIG. 10 cannot be obtained as signals whose phases are shifted by exactly 120 degrees. Inaccuracy makes optimal control difficult. Therefore, after starting the motor, if the rotor position is detected using only one (for example, only Ha) from the plurality of rotor position detecting means 10, the influence of the variation in the mounting position of the rotor position detecting means 10 is eliminated. The position of the rotor can be accurately detected.
[0067]
When adjusting the mounting position of the rotor position detecting means 10 such as a Hall IC, the mounting position of the rotor position detecting means 10 to be used after startup is adjusted with the highest priority. This is particularly effective when a plurality of rotor position detecting means are provided on one substrate.
[0068]
<Tenth embodiment>
Next, a tenth embodiment of the present invention will be described. When assembling the brushless DC motor 7 (see FIG. 1), the rotor position detecting means 10 is attached as described in the seventh embodiment. After the attachment, the rotor position signal from the rotor position detecting means 10 and If the induced voltages of the motor 7 are measured and they do not match, the position detection of the rotor will be inaccurate as it is, and the correction amount for performing the correction from the rotor position signal will be E²The data is written in a storage device 11 (see FIG. 1) such as a PROM (electrically rewritable ROM) or a flash memory. For example, the rotor is operated clockwise at a certain rotation speed at a constant speed, and the time during which the rising edge of the rotor position signal and the zero-cross point of the induced voltage deviate is measured. Write it in
[0069]
As a result, the washing machine takes out the correction value from the storage device 11 and corrects the rotor position signal from the rotor position detection means 10 so that the rotor position can be accurately detected. As described above, even if the arrangement position of the rotor position detection means 10 is slightly shifted, the correction amount is stored in the storage device 11 so that the washing machine can correct the rotor position signal while correcting the rotor position signal while operating. And the rotor position can be accurately detected. For this reason, it is not necessary to adjust the mounting position of the rotor position detecting means 10 during the production of the motor, so that the productivity is improved.
[0070]
<Eleventh embodiment>
Next, an eleventh embodiment of the present invention will be described. In the rotor position detecting means 10 (see FIG. 1) using a Hall IC or the like, even when the motor 7 (see FIG. 1) is stopped, the N / S poles of a plurality of magnets in the rotor and a plurality of rotors for detecting the N / S poles A plurality of signal patterns can be obtained by combining the rotor position signals from the position detecting means, and the absolute position of the rotor can be detected. However, if there are variations in the mounting positions of the plurality of rotor position detecting means, accurate rotor position detection cannot be performed, and the mounting positions must be adjusted for accurate detection.
[0071]
In the present embodiment, a sensing winding (induced voltage detecting means) for detecting an induced voltage is wound around the stator winding. As a result, no signal is obtained in the sensing winding when the motor 7 is stopped, but when the rotor starts to rotate, an induced voltage is applied to the sensing winding wound on the stator winding due to a magnetic field change due to rotation of a magnet in the rotor. appear. The rotation state of the rotor can be detected in real time by detecting the induced voltage. Since the sensing winding is wound on the stator winding, the position of the rotor can be accurately detected without requiring adjustment.
[0072]
In this way, at the time of startup, the optimum energization is performed so that the torque can be maximized according to the rotor position based on the rotor position signal using the rotor position detection means using a Hall element or the like that can detect the rotor position even in the stopped state. The pattern is output from the inverter unit 8 (see FIG. 1) and the motor 7 is started. After the startup, at a certain rotation speed, for example, about 100 rpm, the energization pattern is determined based on the induced voltage detected by the sensing winding.
[0073]
Thereby, the maximum torque can be output at the time of starting, regardless of the capacity and the balance state of the laundry. This eliminates start-up mistakes and enables accurate position signals to be detected after start-up, enabling high-efficiency operation and reducing vibration and noise.
[0074]
【The invention's effect】
As described above, claim 1 of the present inventionOr Claim 2According to the method, the reluctance torque generated in the magnetic material portion is generated in addition to the magnet torque generated by the rotor magnet, so that the motor torque is improved. Therefore, if the same torque is obtained, the rotor shape can be made smaller than that of the conventional brushless DC motor, so that the weight is reduced and the cost is reduced. Further, since the magnet does not have to be used on the entire surface of the rotor, the cost of the magnet material can be reduced.In addition, since the windings of the same phase are wound around the two adjacent teeth so that the winding directions are different, the torque acting from the two teeth of the same phase is dispersed. As a result, torque ripple can be reduced, and noise and vibration can be suppressed.
[0075]
Claims of the present invention3According to this, even when the magnet portion and the magnetic material portion are formed of independent pieces, the magnet portion and the magnetic material portion are fixed by the member made of the non-magnetic material, so that they do not scatter. Further, since the member is made of a non-magnetic material, it does not disturb the magnetic flux from the stator winding, so that the efficiency can be improved.
[0076]
Claims of the present invention4According to this, since the rotor is embedded in the magnetic material portion, it is possible to prevent the magnet from scattering due to centrifugal force during high-speed rotation of the rotor and to fix the magnet position accurately.
[0077]
Claims of the present invention5According to the above, since the rotor has a skew structure, the peak of the torque is dispersed. Thereby, torque ripple can be reduced, and noise and vibration can be suppressed.
[0078]
Claims of the present invention6According to this, by vacating the inside of the rotor, other components such as a clutch mechanism can be built therein. Therefore, the size of the motor can be reduced.
[0079]
Claims of the present invention7According to this, since the rotor has a cantilever structure, a bearing for supporting the shaft of the rotor is not required on one side of the motor. Therefore, the thickness of the entire motor can be reduced.
[0081]
Further, according to the eighth aspect of the present invention, the mounting position of the rotor position detecting means is set so that the phase of the waveform of the rotor position signal and the phase of the waveform of the induced voltage match, so that the mounting position becomes clear. Further, since the phases match, drive control of the rotor based on the rotor position signal is facilitated.
[0082]
According to the ninth aspect of the present invention, since the washing machine uses the brushless DC motor using the magnet torque and the reluctance torque, the washing machine has less noise and vibration.
[0083]
According to the tenth aspect of the present invention, since the rotor position signal has the same phase as the induced voltage, the magnet torque is mainly used by applying a voltage having a waveform that matches the rotor position signal to the brushless DC motor. To drive the motor. Therefore, starting errors can be reduced particularly in low-speed, large-load operation.
[0084]
According to the eleventh aspect of the present invention, the induced voltage increases during high-speed operation, and it becomes difficult to effectively use the magnet torque. However, the voltage of the waveform having a phase advanced from the waveform of the rotor position signal is transferred to the brushless DC motor. , The reluctance torque can be effectively used, so that high-speed operation is facilitated. Therefore, noise and vibration can be reduced.
[0085]
Further, according to the twelfth aspect of the present invention, even if the motor is stopped, the rotor position can be detected from the rotor position signals obtained from the plurality of rotor position detecting means, so that the motor can be started. After startup, the use of only one of the rotor position detecting means eliminates the influence of the variation between the detecting elements, and improves the control performance of the motor. This enables high-efficiency operation and reduces noise and vibration.
[0086]
Further, according to the thirteenth aspect of the present invention, since the correction value for correcting the phase shift between the rotor position signal and the induced voltage can be stored in the storage device, the shift amount is measured after the detection element is attached during the production of the motor. By writing the correction amount into the storage device, the washing machine can accurately detect the rotor position. Therefore, the mounting accuracy of the detecting element at the time of production may be coarse, so that the productivity is improved, and the dispersion of the mounting position is individually managed one by one, so that the control performance of the motor is improved.
[0087]
Further, according to the fourteenth aspect of the present invention, the rotor position can be accurately detected by utilizing two cases, that is, the case where the rotor position is detected by a rotor position detecting means such as a Hall IC and the case where the induced voltage is detected. Since the detection can be performed, the control performance is improved, the motor control can be reliably performed without performing the correction at the time of motor production, and the productivity is also improved.
[0088]
According to the fifteenth aspect of the present invention, there are two types of the detection of the rotor position, namely, a case where the rotor position detection means such as a Hall IC detects the rotor voltage, and a case where the induced voltage is detected. By using the rotor position detecting means that can be used, the starting characteristics are improved, the maximum torque can be output regardless of the capacity and the state of balance of the laundry, and starting errors are eliminated. In addition, after starting, the accurate position can be detected at any time by the induced voltage detecting means, so that high-efficiency operation can be performed and vibration and noise can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a washing machine according to an embodiment of the present invention.
FIG. 2 is a circuit diagram showing an internal configuration of a motor drive unit of the washing machine.
FIG. 3 is a principle diagram of magnet torque and reluctance torque of the brushless DC motor of the washing machine.
FIG. 4 is a structural view of a rotor of the brushless DC motor according to the first embodiment.
FIG. 5 is a structural diagram of a rotor of a brushless DC motor according to a second embodiment of the present invention.
FIG. 6 is a structural diagram of a rotor of a brushless DC motor according to a third embodiment of the present invention.
FIG. 7 is a structural diagram of a rotor of a brushless DC motor according to a fourth embodiment of the present invention.
FIG. 8 is a structural diagram of a rotor of a brushless DC motor according to a fifth embodiment of the present invention.
FIG. 9 is a structural diagram of a rotor of a brushless DC motor according to a sixth embodiment of the present invention.
FIG. 10 is a diagram illustrating a relationship between a rotor position signal and an induced voltage waveform of a brushless DC motor according to a seventh embodiment of the present invention.
FIG. 11 is a diagram illustrating a relationship between a rotor position signal, an induced voltage waveform, and an inverter output waveform during a washing / rinsing process of a washing machine according to an eighth embodiment of the present invention.
FIG. 12 is a diagram showing a relationship between a rotor position signal, an induced voltage waveform, and an inverter output waveform during a spin-drying process according to the eighth embodiment.
FIG. 13 is a structural diagram of a rotor of a conventional brushless DC motor.
[Explanation of symbols]
1 washing machine body
2 Dehydration tank
3 aquarium
4 Suspension
5 Pulsator
6 Clutch mechanism
7 Motor
8 Inverter section
9 Control unit
10 Hall IC (rotor position detecting means)
10a, 10b, 10c detection element
11 Storage device
24 Rotor position detection circuit
41 Stator
42 winding
43 Rotor
44 magnet part
45 Magnetic Material Department
46 Holding plate
47 axes

Claims (15)

In a brushless DC motor composed of a rotor and a stator,
In the rotor, the magnet portion and the magnetic material portion are arranged so as to be alternately radial ,
A brushless DC motor, wherein the stator has a plurality of teeth, and windings of the same phase are wound around two adjacent teeth so that the winding directions are opposite to each other . In a brushless DC motor including a rotor and a stator having a plurality of teeth,
In the rotor, the magnet portion and the magnetic material portion are alternately arranged in a radial pattern, and in the stator, windings of the same phase are wound around two adjacent tooth portions so that the winding directions are opposite to each other. Accordingly, features and be Lube Rashiresu DC motor that the phase act of magnet torque and the reluctance torque is shifted. Brushless DC motor according to claim 1 or claim 2 wherein the magnetic material portion and the magnet portion is characterized in that it is fixed by a member of non-magnetic material. Brushless DC motor according to claim 1 or claim 2 wherein the magnet unit is characterized in that embedded in said magnetic material portion. 3. The brushless DC motor according to claim 1, wherein the magnet portion and the magnetic material portion have a skew structure twisted in an axial direction of the rotor. 3. The brushless DC motor according to claim 1, wherein the rotor includes the magnet portion and the magnetic material portion arranged on a disk-shaped holding plate along an outer periphery of the holding plate. 4. 3. The brushless DC motor according to claim 1, wherein the rotor has a cantilever structure having one end supported by a shaft. At least one rotor position detecting means for detecting a rotor position based on the position and the magnetization direction of the magnet unit and outputting a rotor position signal is generated when the brushless DC motor rotates with the waveform of the rotor position signal. 8. The brushless DC motor according to claim 1, wherein the brushless DC motor is provided at a position where the phases of the waveforms of the induced voltages match. In a washing machine including a brushless DC motor that rotationally drives a pulsator and a dewatering tub, and a motor drive unit that variably controls the number of revolutions of the brushless DC motor,
A washing machine, wherein the brushless DC motor is the brushless DC motor according to claim 8. The washing machine according to claim 9, wherein the motor driver applies a voltage having a waveform that matches a waveform of the induced voltage to the brushless DC motor based on the rotor position signal. The washing machine according to claim 9, wherein the motor driver applies a voltage having a waveform having a phase advanced from the waveform of the rotor position signal to the brushless DC motor. The motor drive unit activates the brushless DC motor based on the plurality of rotor position signals obtained by the plurality of rotor position detection units when the brushless DC motor is activated, and one of the rotor position detection units after activation. The washing machine according to claim 9, wherein the brushless DC motor is driven based on the rotor position signal obtained only by the brushless DC motor. The washing machine according to claim 9, further comprising a storage device that stores a correction value for correcting a deviation between the waveform of the rotor position signal and the waveform of the induced voltage. And a motor drive unit for driving the brushless DC motor by correcting a phase shift between a waveform of the rotor position signal and a waveform of the induced voltage in real time. 10. The washing machine according to 9. The motor drive unit drives the brushless DC motor based on the rotor position signal when the brushless DC motor starts, and based on the induced voltage after startup. The washing machine according to claim 9, which drives a brushless DC motor.

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