JPH0923687A - Magnet motor and activating system thereof - Google Patents

Abstract

PURPOSE: To eliminate dead point of activation and reduce non-energization cogging torque by introducing directivity in a magnetic circuit to deviate a rotor magnet. CONSTITUTION: Respective stator tips have equal circumference angles and sets the angle 2p of the rolling direction, namely the magnetization-easy angle to 10 degrees in the counterclockwise direction for the center angle 2q of teeth 2c. Therefore, the magnetic center on the external circumference of each tip moves from the center angle of teeth as indicated by black points 2a1, 2b1. From the relative relationship of circumference angle between tip and pole, the cogging torques of pole sections are cancelled with each other. Therefore, non-energization axis torque becomes almost zero without relation to the pole position. In addition, when a motor is rotated using a simplified drive circuit such as single phase bipolar and double-phase bipolar by mixing the teeth having provided excitation coil and the teeth not providing the coil, a torque generated in the inverse direction generated on each magnet coil can be reduced. Therefore, a rotating shaft torque can be smoothed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor structure and an excitation method capable of improving the characteristics of a small DC precision brushless magnet motor suitable for the field of OA and the like by using a novel electromagnetic technique. More specifically, the present invention relates to a motor structure and an excitation method for achieving characteristics in single-phase bipolar or two-phase unipolar excitation that are comparable to those of the three-phase bipolar method which has been widely used in the field of small DC precision motors.

[0002]

2. Description of the Related Art Conventional magnet motor technology can be classified into two systems. In a brushless magnet motor used in a field where torque ripple is a problem, such as a motor of one system, such as an HDD spindle motor, an asynchronous magnetic that cancels the non-energized cogging torque by setting the magnet pole and the stator tip or the number of slots to odd and even In addition to adopting a circuit, three Hall elements are used for the three-phase coil, and the coils of two phases among the three phases are sequentially energized and rotated. The problems to be solved by this method are that one of the three phases is always in a rest state, so the torque is weakened at that rate, and the number of components is relatively large and complicated. In a motor of the other system, such as an axial fan, for brushless magnet motors where torque ripple is not a problem, synchronous torque is generated by setting the number of slots and poles to the same number, and a relatively high torque is obtained to reduce the motor size and cost. The method of doing is adopted.
The problem in this case is that the torque ripple and vibration increase with synchronous rotation, and the asymmetric air gap is used to avoid the start dead center, so the average length of the gap increases and the efficiency of the motor is inevitably reduced. Is to be done.

FIG. 2 shows a cross section of the basic magnetic circuit of such a conventional three-phase asynchronous motor. In the figure, 1 is a sine wave-like octapole magnetized annular rotor magnet, 11 is a magnetized zero-cross portion, and 12 is a rotor yoke. Reference numeral 2 denotes a stator core formed by punching out and stacking six projecting teeth 2a, 2b, ..., 2f and an isotropic silicon steel plate having holes for mounting a shaft and a bearing in the center. An outer rotor type magnetic circuit is composed of the magnet 1 and the stator 2. Teeth 2a, 2b, ...
.., 2f have tips facing the inner peripheral surface of the magnet 1 at their outer peripheral ends. The coils 3a, 3b, ..., 3f are wound around each tooth, and the coils 3a-
3d, 3b-3e, and 3c-3f are connected in series, and the coil lead terminals 3ad, 3be, 3cf are connected.
Are connected to Y or Δ. The neutral point CT is used at the request of the drive circuit. An air gap 4 is formed between the inner circumference of the magnet 1 and the outer circumference of each tape,
Hall sensors 5a, 5b, and 5c are mounted at 120 ° intervals on a base plate (not shown) in the gaps between the tips of the teeth 2a-2b, 2c-2d, and 2c-2f.

The magnetic circuit of FIG. 2 has 6 slots and 8 poles, which is twice the basic combination of 3 slots and 4 poles.
When the combination of 3 to 4 is included, the non-energized partial torque generated in each individual tip can be canceled.
That is, FIG. 3 schematically shows aspects of non-energized torque and energized torque generated in the magnetic poles of the rotor magnet. At each energization phase u-> v, w-> v, ... In FIG. 3, the rectangular frame shown above has the stator tips 2a, 2b ,. Seen from the outside of the circumference of the air gap 4, it is developed on the paper surface. The solid line stripes shown below are the developed positions of the magnet poles facing each tip, and the presence or absence of non-energized cogging torque and the direction are indicated by the symbols "<,>" at the left end of each pole. Since the non-energized torques of the respective poles cancel each other as shown in the figure, in the magnetic circuit of FIG. 2, no cogging torque is generated in the axial torque regardless of the position of the rotor. Therefore, current is applied to each phase of (U), (V), and (W), and “filled-out Δ (triangle vertices indicate the direction of torque)” with respect to the magnetized central portion of each magnet pole.
When the energizing torque as shown by is generated, a partial rotating torque is not generated regardless of the energization switching phase and the rotating direction of the rotor, and a constant rotating torque is obtained. As a result, there is an advantage in application that the torque ripple during energization and hence the mechanical vibration is small, and it is favorably used in OA precision motors. However, in a DC-powered magnet motor as shown in FIG. 2, two phases among (U), (V), and (W) are sequentially supplied even though it is called three phases. One phase is always in the dormant state as indicated by "-". Therefore, this motor only uses 2/3 of the total magnetic energy of the magnet, and there is room for improvement in efficiency.

The conventional three-phase motor shown in FIG. 2 is started as follows. When the coils of each phase of (U), (V) and (W) are bipolar-excited, an energization switching circuit using a three-phase bridge made of a hidden six-stone semiconductor is usually used.
That is, for example, the (U) phase terminal 3ad is connected to the middle point of the two semiconductor switches connected in series, and the (V) and (W) phase coil terminals 3be are connected to the other two middle points in the same manner.
3cf is connected. Each switch has a sensor 5a, 5
The output signals of b and 5c are signal-processed, compared and given, and the exciting currents of the coils of each phase are switched by selectively opening and closing each switch, and an alternating torque with a phase shift of 120 ° is generated in each phase. . That is, at the time of energization, two phases out of the three phases that are in the most effective energization phase with respect to the rotor magnet 1 are selected, and the two phases are energized to generate the required starting torque. As a result, when the rotor magnet 1 starts to rotate, the timing at which the zero crossing 11 for magnetization arrives so as to cross the large amplitude portion of the torque curve of each phase of (U), (V) and (W) while continuing to maintain high torque. The one-phase semiconductor switch is commutated accordingly. As a result, a shaft torque of a certain value or more is always generated, and the starting dead center can be avoided.

When the motor is started, the one-phase energization of the three phases is maintained, and the two-phase energization is sequentially switched by a method of commutating the one-phase energization. By repeating this, the energization cycle is gradually shortened, the rotation speed is increased, and the desired rotation speed is reached. During this period, two of the six semiconductor switches are activated, and the rest are in the resting state, so the utilization rate of the semiconductor switches is 1/3. In addition, if you supply power to the remaining one phase with this energization method,
Torque is generated in the direction opposite to the rotation direction. Therefore, it is not possible to energize all phases.

While such an asynchronous motor has characteristics suitable for OA and is frequently used, it also has the following drawbacks. First, all of the available magnetic energy is not being used because one phase has been discarded to eliminate cogging torque. Second, the moter structure is relatively complex and expensive. Thirdly, it is sensitive to the characteristic variations of the members.
For example, the three sensors are required to have a balance of characteristics, but it is difficult to obtain a large amount of uniform characteristics at all times. Therefore, a compensating action is added to the circuit side, but there are sensors that cannot be used. Fourth, the drive circuit is also relatively complicated, has a large number of elements, and is expensive. Fifth, since the number of terminals or the number of lead wires is large, the connecting means becomes complicated. For this reason, it is necessary to take measures such as mounting the IC on the base plate of the motor to reduce the number of lead wires.

On the other hand, the characteristics of the magnetic circuit of a non-display synchronous motor used for an axial fan or the like will be briefly described as follows. Generally, in a magnetic circuit in which the number of tips and poles is the same, the maximum value of the non-energized torque reaches a very large value because there is a rotation angle at which all the pairs of tips and poles simultaneously attract each other. There is also an angle where the electromagnetic force of all pairs becomes zero. Therefore, in the synchronous motor, the non-energized cogging torque reciprocates between the maximum value and zero, and a stable point, which is a multiple of the pair, that is, a starting dead point is encountered during one rotation of the rotor. Half of them are unstable asphyxia, and half are stable and true dead points, and the rotor angle where the magnet pole and the tip attract each other corresponds to the true starting dead point.

If this starting dead point is overcome by some method, the relative relationship between a certain pole and tip is the same in other parts, so that a simple motor can be constructed with one sensor. As a conventional method for overcoming the dead point, a method in which a part of the stator tip is cut out to declinate the rotor magnet and the magnetic flux is linked to the sensor is typical. However, in a synchronous motor, the energization torque during rotation after startup also increases or decreases with a large amplitude in synchronization with the number of tips and poles facing each other.Therefore, the energization torque and the energization torque synergize with each other to double the energization frequency when the motor rotates. Wave vibrations occur, exhibiting a vibration spectrum in which energy is concentrated at one frequency, and a torque ripple with a large amplitude is mixed in the shaft torque. Further, if the tip is provided with a notch for starting, ripples due to increase / decrease in reluctance of the air gap are mixed, and motor efficiency is reduced due to increase in average gap length. However, in the synchronous motor, since all the teeth can be activated at the same time, magnetic energy can be used without waste, and as a result, higher torque can be generated and higher efficiency can be obtained as compared with the asynchronous motor.

The characteristics of such a synchronous magnet motor are in contrast to those of an asynchronous motor, and thus it is difficult to use them as precision motors for OA applications that dislike torque ripple.
However, since it can generate torque exceeding that of the asynchronous motor, it is suitable for applications that simply require high torque and high efficiency.

[0011]

The first problem of the present invention is that the above-mentioned typical two types of conventional magnet motors have the problem that a three-phase motor without cogging has relatively low efficiency and is complicated and expensive. On the other hand, among the advantages and disadvantages of a synchronous motor having a simple structure, which has a large torque ripple, it is to provide a new magnet motor that has both advantages and disadvantages.

A second object of the present invention is not only to solve the problems of the prior art but also to combine a new magnetic circuit with a new start-up method so that a single-phase bipolar or dual-phase circuit has been considered difficult. The goal is to achieve zero dead point activation in phase unipolar excitation without the provision of special auxiliary equipment.

A third object of the present invention is to achieve a higher torque and a higher motor efficiency than conventional three-phase bipolar in single-phase bipolar excitation by combining a new magnetic circuit and a new drive circuit. .

A fourth object of the present invention is to reduce the torque ripple during rotation in single-phase bipolar or two-phase unipolar excitation by combining a new magnetic circuit and a new drive circuit.

[Means for Solving the Problems]

According to the present invention, a rotor having a rotating shaft, a hard magnetic material having magnetic poles on its circumferential end face, for example, a ring-shaped rotor magnet, a plurality of teeth and a soft magnetic material having tips facing the magnetic poles at its circumferential end face. For example, in a magnet motor having a stator, an exciting coil wound around the teeth, a unit for detecting the magnetic pole position of the magnet, and a drive circuit for energizing the coil, the relative positions of the plurality of tips and the magnetic poles. The positional relationship is selected such that the axial torque obtained by integrating the non-energized partial torques generated in the individual tips is almost zero depending on the combination of the two, and the stator teeth have a magnetizing coil and those that do not. By selecting the position of the teeth and tips, Means for reducing the reverse torque component in the partial torque generated in the magnetic pole Te used. Further, the angle occupied by the plurality of teeth and the tip width in the rotation circumference, the circumferential angle occupied by the gap between the tips, the winding position of the exciting coil, the polarity, and the number of turns are selected to different values. Therefore, the means for further reducing the partial reverse torque is used.

At least a part of the stator is directional. By this means, the angle formed by the center axis of each tooth and the axis of easy magnetization of the material is made different for each tooth, and the magnet is energized when the coil is not energized. The magnetic flux supplied from the magnetic pole to the tip is unevenly distributed, the magnetic field is interlinked with the magnetic pole detecting means, and the energization to the coil is started by the detection output, and a desired rotation is generated between the magnetic pole and the tip. An electromagnetic force is generated in the direction to activate the rotation of the rotor.

The drive circuit has means for reversing the energizing direction of the exciting current for a certain period at the time of starting, and when the teeth are momentarily excited in the opposite direction, the rotor is rotated based on the directionality of the easy axis of magnetization. With respect to the rotation angle, the axial torque having a phase different from that in the case of positive direction energization is generated, so that the phase is different in the period in which the axial torque of the positive direction energization corresponds to a low value compared to zero cross or shaft loss. It includes a starting circuit for generating a high shaft torque by reverse energization.

More specifically, the magnetic flux detecting means is a Hall element, and based on the fact that the phase difference between the easy axis of magnetization and the induced magnetic flux of the excitation winding changes according to the circumferential angle, By arranging the Hall element at a position where the phase difference of the shaft torque generated by energization in the opposite two directions makes an electrical angle of about 90 °, and reversing the energization direction for a short time at the time of starting, energization in one direction is performed. When the generated axial torque corresponds to zero or a low value, the rotation of the rotor is started by using the axial torque having a large amplitude due to the other energization. The inversion period of the polarity recognition of the starting circuit is determined by, for example, the time constant of the charging / discharging circuit, and its reverse excitation period is preferably set to a value that substantially matches the mechanical resonance frequency of the motor and the load, and after starting The reverse excitation effect due to the time constant is released.

Alternatively, the magnetic flux detecting means is a coil wound around the non-winding tooth, and the magnetic flux interlinking with the coil is inclined from the radial direction corresponding to the easy axis of magnetization. Based on or based on the fact that the direction of the magnetic flux dynamically changes in response to energization by energization, the rotational direction of the rotor is identified and activated by the induced voltage in the coil that exhibits an output waveform that differs depending on the rotational direction. At this time, when the generated axial torque corresponds to zero or a low value, rotation is started by using a high axial torque based on the phase difference in which the interlinkage flux differs depending on the other energization direction.

The first feature of the various means according to the present invention is that the stator tip is left in a symmetrical shape without a notch, and the magnetic characteristics that gradually change according to the circumferential angle are given by giving directionality to the material. It is based on giving to. According to this method, the torque ripple based on the energized partial torque can be reduced by skipping the tip that generates the reverse torque during the energized torque when the non-energized shaft torque is reduced. For this purpose, non-winding teeth are provided, or the angle between the center angle of the teeth and the axis of easy magnetization and the tip shape are set.

The second feature of the various means according to the present invention is that not only the rotor magnet is declined when no current is applied by introducing directionality into the magnetic circuit, but also the declination of the rotor can be promoted by energization. . That is, in the directional stator, the angle difference between the axis of easy magnetization and the central angle of each tooth is different, and therefore the magnetism is different. For example, since the saturation flux density differs depending on the teeth, when each tooth is energized and excited, each tooth saturates at a different level based on the magnetization level of the current and the polarity of the excitation. Therefore, some teeth are more saturated and some teeth are released from saturation a little, resulting in the dynamic promotion of declination and spin of the rotor. Therefore, in the present invention, even when there is no angle difference between the axis of easy magnetization of the stator and the tooth center angle, the rotor magnet can be spun for the reason different from the case where the angle difference is provided.

A third feature of the means according to the present invention is that when the magnetic detection means is arranged at a certain circumferential angle to switch the direction of the exciting current, the CW rotation is caused based on the difference in the magnetic characteristics of the respective tips. The CCW rotation consists in obtaining different torque curves. Therefore, at startup, if the energization direction is forcibly switched by some method, the activation dead center can be eliminated by energizing at least one of them. The magnetic detection means may be a Hall element or coil detection, and is preferably arranged in the vicinity of the gap between the tips or the non-winding teeth in order to avoid the influence of the induced magnetic field. Especially in the latter, CW and CCW
The direction of rotation can be detected by only one coil due to the difference in the voltage output in each direction.

As another means for obtaining the magnetic field deflection according to the present invention, a magnet having a magnetic flux distribution deflected with respect to the rotation angle can be used instead of the directional stator. For example, the magnet may be magnetized to have a magnetic flux distribution that is asymmetric with respect to the rotation angle, such as a sawtooth wave, or an anisotropic magnet may be used to set the orientation direction to a non-radial direction and By including the magnetization, the direction of the magnetic flux emitted to the air gap or the magnetic flux flowing through each tooth is slightly directed to make the magnetic flux distribution asymmetric with respect to the rotation direction, and the declination of the rotor can be obtained. Furthermore, the directivity of the stator and the anisotropy of the magnet can be used together.

The magnetic circuit of the present invention can be applied to an asynchronous motor in which the number of poles of the rotor magnet and the number of stator teeth or tips are different. Possible logarithms are, for example, 5: 4, 5: 6 and the like. In this case, the exciting coil is not provided in all the teeth, and in the case of the previous example, one of the five teeth has no exciting coil. The ratio of non-excited teeth to all teeth is
It can be made smaller than the conventional three-phase bipolar excitation, and for this reason includes the possibility of generating more torque than the conventional three-phase motor. Even if the material of the stator is made non-directional, which is often used in the past, a high torque can be generated by increasing the ratio of the active teeth and reducing the reverse torque. However, in the case of an isotropic core, starting means by an auxiliary winding or other method is indispensable, and the motor and drive circuit are inevitably complicated as compared with the case of a directional core.

The magnetic circuit of the present invention is effective when the tips having a uniform circumferential angle and the magnetic poles of the magnet are set to the special asynchronous ratio as described above, and the tips having different circumferential angles or It can also be applied to magnetic poles,
The characteristics can be further enhanced. Different circumferential angles can be used as supplementary means when a slight reverse current torque remains in the uniform tip shape or magnetization. For the principle, refer to the specification and drawings of the patent application (name: magnet motor) filed by the applicant on May 12, 1995.

The motor of the present invention is used in combination with a simple drive circuit such as a single phase bipolar. In this case, the teeth coils are all connected in series or are composed of parallel circuits including the same number of magnetizing coils and demagnetizing coils. Alternatively, each coil may be composed of two parallel windings, and bifilar windings may be used to alternately connect two current-carrying paths. Another drive circuit of the present invention is a two-phase unipolar. In this case, the teeth coil is composed of two parallel electric wires and is alternately energized. The magnetic operation is the same as that of the single-phase bipolar except that the excitation causes a pause period.

[0027]

Since the magnet motor of the present invention introduces directionality into the magnetic circuit, unlike the conventional synchronous motor using a nondirectional magnetic circuit, the rotor magnet can be declined without providing a notch in the tip. As a result, not only the starting dead center can be eliminated, but also the non-energized cogging torque is reduced. In addition, the magnetic characteristics differ for each stator tape, and the characteristics can be changed in accordance with the current change during energization, so it is possible to change the electromagnetic force generated in each magnetic pole and dynamically cancel the start dead point. it can. Such a property is caused by the directivity of the electromagnetic force in the directional magnetic circuit, but the details of the action are submitted by, for example, one of the applicants on February 7, 1994. Please refer to the specification and drawings such as the patent application (Japanese Patent Application No. Hei 6-35325).

Such anisotropic magnetism can be applied not only to a soft magnetic material such as a silicon steel plate, but also to a hard magnetic material such as a magnet. When using a magnet, include a magnetized portion that is asymmetric with respect to the rotation direction, such as sawtooth wave magnetization, or include a portion that is oriented from the radial direction of the anisotropic material. By means of this, it is possible to impart an action similar to that of the stator. Moreover, the effect of the present invention can be emphasized by providing anisotropic magnetism to both the stator and the magnet.

In the magnet motor of the present invention, only one sensor can be used as in the conventional synchronous motor. That is, the magnetic circuit of the present invention exhibits a symmetrical torque waveform in the forward and reverse directions in the conventional non-directional magnetic circuit when the energization direction of the exciting coil is reversed, whereas it is based on the directivity of the magnetic circuit. Generates asymmetric torque in the forward and reverse directions with respect to the rotation direction. Since the generated torque in both the forward and reverse directions has a phase shift based on the directionality of the magnetic flux, it is possible to obtain a starting torque at any rotor position by using this property, as in the conventional three-phase motor.

With regard to the switching of the energizing direction, the current at the time of current reversal changes from -X [A] to + X [A], but in the conventional general starting circuit, from 0 [A] to X [A]. Therefore, in the magnet motor of the present invention, a current change that is double that of the conventional one can be obtained with the same effective current, and twice as much starting torque can be generated as compared with the start of energization.
For details of the configuration and the effect of such a reverse excitation circuit, refer to, for example, the specification and drawings of the patent specification (Japanese Patent Laid-Open No. 4-304192) filed on March 29, 1991 by the applicant. I want to be done.

In order to execute the reverse excitation described in the preceding paragraph, for example, the recognition of the sensor voltage is reversed or a timer circuit for charging / discharging is used, and at the time of start-up, the direction opposite to the normal rotation direction is kept for a certain short time. Just turn on the power. The length of this energization period is not a long time in which the rotor actually rotates in the opposite direction, but a short time on an electrical or electromagnetic scale. If this reverse excitation period is made to substantially match the motor and additional mechanical resonance frequency, magnetic energy can be efficiently converted into mechanical energy. As an example of a drive circuit that executes such a reverse excitation operation, the specification and drawings of a patent application (Japanese Patent Application No. 6-172677) filed on July 25, 1994, in which the present applicant is involved Can be mentioned.

In the magnet motor of the present invention, like the conventional three-phase motor, the non-energized cogging can be eliminated by selecting the stator tip and the magnet pole in advance in a specific relationship of non-synchronization. In addition, in the magnet motor of the present invention, when the teeth provided with the exciting coil and the teeth not provided are mixed, when the motor is rotated using a simple drive circuit such as a single-phase bipolar or a two-phase unipolar, it is usually It is possible to reduce the reverse torque generated in the magnet pole. Therefore, the rotating shaft torque is smoothed,
Smooth and quiet rotation comparable to that of a conventional three-phase motor can be obtained.

In the magnet motor of the present invention, when the ratio of the idle teeth in the total number of teeth can be reduced to a value of 1/3 or less in the conventional three-phase motor, the generation of partial reverse torque can be suppressed. Therefore, it is possible to obtain the rotation torque and the motor efficiency higher than those of the conventional three-phase motor. With the above configuration, both low torque ripple and high efficiency can be achieved, and further, a simple and compact configuration and a low price can be realized.

[0034]

1 shows a cross section of a magnetic circuit according to a first embodiment of the present invention. In the figure, most of the symbols of each part are common to the symbols of FIG. The magnet 1 is an anisotropic rubber ferrite magnet subjected to a 4-pole sinusoidal radial uniform magnetization. The stator 2 has five teeth and is formed by a core formed by laminating 20 unidirectional silicon steel plates. Each stator tip has a uniform circumferential angle, and its rolling direction, that is, the easy axis of magnetization is set in the direction of the arrow 2p on the paper surface. The angle of 2p is inclined 10 ° counterclockwise with respect to the center angle 2q of the tooth 2c. Therefore, the magnetic center on the outer circumference of each tip moves from the tooth center angle as shown by black circles 2a1, 2b1, .... The shape of the tip periphery is symmetrical with respect to the rotation direction, and the air gap 4
The intervals are constant.

FIG. 4 schematically shows the pattern of the partial torque generated in the magnet pole of the first embodiment of FIG. 1 by the same method as in FIG. At the pole position in the figure, the manner in which the rotor magnet rotates as it goes downward is represented by the movement of a vertical line such as the zero cross 11. In the figure, it can be seen that the non-energized shaft torque becomes almost zero regardless of the position of the poles because the cogging torques shown at the left ends of the pole portions cancel each other out due to the relative relationship between the tips and the circumferential angle of the poles. It should be noted that even if the stator shape is the same, it is stated in the above-mentioned patent application filed on May 12, 1995 that the non-energization torque can be reduced due to the uneven distribution of magnetic flux when the material is changed from non-directional to directional. ing.

Excitation coils 3a, 3b, 3d, and 3e are wound around the teeth 2a, 2b, 2d, and 2e, and the coil polarities are, for example, magnetized, demagnetized, magnetized, and demagnetized, all connected in series. Therefore, the tooth 2c is not provided with an exciting coil. The Hall sensor 5 is installed on the hidden base plate in the vicinity of the teeth 2c, between the teeth 2c and the teeth 2b in the figure. Since the teeth 2c have no exciting coil, the sensor 5 can stably detect the zero cross 11 of the rotor magnet. If the sensor 5 is placed in a slot with an exciting coil, the sensor position is restricted to a relatively narrow angular range, especially in the case of multiple slots, which is influenced by the induced magnetic field. As will be described later,
Instead of the sensor 5, a sensor coil may be wound around the tooth 2c. By allocating the exciting coils to the positions of the teeth in this way, most of the energization torque generated in each tip can be directed in the rotation direction, and the rotation torque can be increased.

In the first embodiment of the present invention, the motor constructed as shown in FIG. 1 is loaded into the drive circuit shown in FIG. 5 and is single-phase excited. In FIG. 5, when a start command is input, the charge / discharge circuit 5e outputs an oscillation waveform determined by the CR time constant,
A reverse rotation command signal is generated according to the increase of the charging voltage, and a positive point command signal is generated according to the decrease of the discharging voltage. Therefore, by giving a command for reverse direction energization to the command signal generation circuit 5h only for a specific period, and inverting the output of the pre-driver 5d via the two-phase distributor 5c, excitation in the reverse rotation direction is performed for a time of 25 ms, for example. It can be carried out. This period is sufficiently short compared to the motor and the rotational load so that the rotor does not rotate in the opposite direction.

When the coil 3 of FIG. 1 is energized in both directions,
When the sensor 5 is arranged at an appropriate position with respect to the angle formed with the easy magnetization axis 2p, a starting torque as shown by the curve in FIG. 6 is obtained. That is, assuming that the coil 3 is energized in the direction in which the forward rotation is given at the time of starting the rotation,
The obtained starting torque draws a locus like a solid line 8a.
If the coil 3 is energized in the opposite direction, the starting torque draws a locus like a solid line 8b. Or keep the energization direction constant and rotate the rotor forward and backward,
Alternatively, the same result can be obtained when the recognition of the magnetic poleability by the sensor 5 is reversed. Comparing the solid lines 8a and 8b, the zero-cross phases of the two curves deviate from each other with respect to the rotation angle θ of the horizontal axis, resulting in an angle difference of 90 °. Such a phase shift of the starting torque curve due to the energizing direction does not occur in the case of the non-directional stator. In the case of a directional stator, since the angle formed by the magnetization easy axis 2q of the stator and the central angle of each tooth differs for each tooth, if the angle is gradually changed to shift the point of energization switching,
The zero-cross phase of the curves 8a and 8b gradually expands from 0 ° and reaches a phase difference of 90 ° as shown in the figure, and further 90 °.
Expand to a phase difference of ゜ or more.

Performing reverse excitation at the time of start-up by the start-up circuit shown in FIG. 4 or the like means reversal of the current direction shown as 8a1 and 8b1 in FIG. That is, if the energizing direction is reversed when the amplitude of the curve 8a is below the reference line 8ab,
The curve 8b having a relatively large amplitude can then be used. That is, performing the reversal of the current direction is equivalent to the curve 8b.
Corresponds to folding back upward with respect to the horizontal axis of torque τ = 0 as indicated by the dotted line. Thus, the torque curve 8
b changes like 8c, and the high amplitude part of each torque curve can be crossed like 81, 82, 83, ... As a result, the starting dead center disappears. In the non-directional stator, the zero cross phase of both curves is common,
There is no dead point elimination effect by reverse excitation, and some kind of starting means is required.

Thus, when the rotor of FIG. 1 starts rotating, the sensor 5 outputs a sine wave-like voltage according to the change of the interlinkage magnetic flux, and this waveform is shaped into a rectangular wave by the sensor amplifier 5b of FIG. By detecting the zero cross, the semiconductor switches 6a-6b, 7a of the final stage circuit of FIG. 5 are detected.
-7b is conducted alternately. As a result, when the rotor rotates and the magnetic pole of the magnet approaches the position where the reverse torque of each tip becomes dominant, the energization direction reverses and the polarity of the electromagnet of the stator reverses. Is accelerated and reaches a predetermined speed. During this time, a partial torque (the direction of the arrow is the direction of the torque) is generated between the five taps and the four poles of FIG. 1 by energization as shown by the symbol “filling Δ” in FIG. .
Comparing the energization torque of FIG. 4 with that of the conventional three-phase motor shown in FIG. 3, it can be seen that in the single-phase one-sensor, many rotor positions are entered during one energization switching.

In FIG. 4, the presence or absence of the partial energization torque and the direction are indicated by the symbols "-, <,>" at the center of each pole, and the presence or absence of the non-energization torque and the direction "-" at the left end of each pole. , Filled Δ, white Δ (triangle vertices indicate the direction of torque) ”. These torques are generated in the central portion of each magnetic pole, and the drawings are drawn with the stator core being non-directional like FIG. In FIG. 4, the non-energized shaft torque is zero, but in the energized partial torque, there are two torques in the direction opposite to the normal rotation direction, and the thick frame of the magnetic pole boundary and the white symbol “white Δ” ”. These torques are
Since the current-carrying shaft torque at the rotor position is pushed down, the generated torque is slightly less than that of the conventional three-phase bipolar system. However, it can be seen that even in this state, the shaft torque with a smaller fluctuation range can be obtained as compared with the conventional synchronous motor.

When the movement of the magnetic center on the outer circumference of each tooth based on the directionality of the stator shown in FIG. 1 is applied to FIG. 4, the magnetic center moves toward the position of the black circle in the figure as shown at the lower end of each tip. To move. Accordingly, the partial torque in the reverse rotation direction corresponding to the tape 2b turns black as indicated by the arrow, and the reverse torque can be corrected to the forward torque. Also,
Since the tooth 2d is also improved, the tooth 2d is improved as a whole even if it is considered to be slightly worse, and a torque close to that of the three-phase bipolar system can be obtained. In order to eliminate all the reverse torque, the patent application filed by the applicant on May 12, 1995 (reference number 230007,
As mentioned in (Name: Magnet motor), it is effective to adopt a shape in which the circumferential angle of each tip or pole is asymmetrical, and in addition to this, frequent energization switching is performed by methods such as double magnetization and double sensor. The method is also effective.

As described above, in the motor of FIG. 1, four tips out of five can be activated at any time, so that a practical level output can be obtained even with the configuration of FIG. Furthermore, when the partial reverse torque is eliminated, the
Since the magnet pole can be activated at a ratio exceeding / 3, a torque output higher than that of a three-phase motor can be obtained in single-phase excitation. With respect to the cause of obtaining high torque, most of the torque of the magnet motor is supplied from the magnet, so it is presumed that it is more effective to reduce the number of pause poles than the influence of the number of excitation phases. With regard to the semiconductor switch, the utilization efficiency can be improved from 1/3 to 1/2 by using the H bridge shown in FIG.

As described above, in the magnetic circuit according to the first embodiment of the present invention, by combining the stator having the directionality of magnetization and the dedicated drive circuit including the simple power stage such as the H bridge, the non-energized cogging torque and the Rotational torque ripple is significantly reduced compared to conventional synchronous motors, and the generation of torque in the opposite direction to the normal rotation direction is reduced or eliminated by the positional relationship between the stator tip and magnet pole, and the selection of excitation teeth. By doing so, it is possible to obtain a torque comparable to that of a conventional three-phase motor, and thus it can be used as a novel motor and drive system having the advantages of the conventional mainstream synchronous and asynchronous three-phase motors. With respect to the simplification according to the present invention, when the reason is inferred from a macro,
Since the phase is given by the magnetic field directionality of the material and the other phase is given by energization excitation, it can be considered that the rotation vector of the magnetic field is imperfectly generated.

Next, FIG. 7 shows the non-energization and energization torques generated in each magnetic pole of the magnet motor of the second embodiment of the present invention. The magnetic circuit of the motor of this embodiment is similar to that of the first embodiment of FIG. 1, except that the circumferential angles of the stator tips are not uniform and are modulated up and down as shown. As a result, generation of reverse torque can be reduced and higher shaft torque can be generated. The symbols in FIG. 7 are described for the non-directional stator as in FIG. The black circles indicate the tendency of movement of the magnetic pole center due to the directionality.

According to FIG. 7, the partial torque in the reverse direction in the non-directional stator is only at one place with respect to the tip 2b, which is improved as compared with the first embodiment of FIG.
It can be seen that when the directional stator is used, this reverse torque can be eliminated by moving the magnetic center of the tip. As a result, the maximum shaft torque is increased as compared with the first embodiment, and exceeds the conventional three-phase bipolar system. On the other hand, the non-energized torque is not completely eliminated, and some remains.

FIG. 8 shows the low voltage C of the third embodiment of the present invention.
The cross section of the magnetic circuit of the thin spindle motor for D-ROMs, and a part of sensor circuit are shown. Many of the symbols in the figures are the same as those used so far. Rotor magnet 1
Is an isotropic Nd plastic magnet magnetized with a sine wave, and eight stator laminations are laminated with a thickness of 0.35 mm per sheet. Direction angle 2p
Since the status lot has more slots as compared with the first embodiment of FIG. 1, it is set by reducing the angular difference from the central angle of the tooth 2c. The numbers of magnet poles and stator tips are 12 and 15 which are three times as many as those in the first embodiment of FIG. Since this structure has a relatively large number of slots, the total height of the coil after winding is low, and is suitable for a thin motor. The shape of each tip and the width of each tooth are the same. An exciting coil is wound around the teeth 2a, 2b, and 2d, 2e, and no exciting coil is wound around the tooth 2c. Repeat.

Tip 2c has no exciting coil,
The sensor coil 51 is wound as the magnetic detection means. Its position forms an angle of about 140 ° with the easy axis of magnetization corresponding to the dead center elimination action described with reference to FIG. 6, and its signal output is given to the sensor amplifier 51c via the filter composed of the resistor 51a and the capacitor 51b. The output of the amplifier is replaced by the output of the Hall amplifier 5b of FIG.
Given to. The sensor coil 51 can know the rotation direction of the rotor based on the fact that the stator 2 is directional or that the direction of the magnetic flux changes during energization due to the directional property. Note that the sensor coil 51 can also be wound on teeth other than 2c that do not have an exciting coil, and can be connected in series, for example, to enhance the detection capability thereof. In such a sensor coil, the exciting coil can be wound, but in that case, it is necessary to cancel the non-signal component by using a plurality of teeth.

Exciting coils 3a, 3b, 3d, 3e, ...
Are wound to be magnetized, demagnetized, magnetized, and demagnetized, all connected in series, for example, connected to the output terminal of the drive circuit in FIG. When the power is turned on, the rotor starts rotating according to the starting principle described with reference to FIG. During this time, the coil sensor 51 detects the zero crossing of the rotation direction and the magnetic flux depending on the directionality of the interlinkage magnetic flux including the stopped state of the rotor, and therefore the reversal of the energization direction is repeated to accelerate the rotor in the forward rotation direction, thereby maintaining the constant speed. To reach. Regarding the coil connection, the demagnetization and demagnetization coils can be regarded as one pair, and a parallel circuit can be configured by including these pairs. However, when the parallel connection is included, it is necessary to select the position of each coil so that the parallel circuit does not cause interference. Further, the exciting coil may be connected in series instead of a single wire to two parallel copper wires to form a bifilar winding, and may be connected to a two-phase unipolar circuit instead of the drive circuit of FIG. .

In the magnetic circuit of FIG. 8, the magnetized portions of the rotor magnet are basically similar to the pattern of FIG. 4, but slightly different torques based on the difference between the angle tip and the easy axis of magnetization. To occur. In the magnetic circuit of FIG. 8, when a non-directional tooth is used for the tip, the cogging torque is weak with respect to the shaft torque at the time of non-energization. However, if the material is changed to the directionality, the cogging torque further decreases, and the component of the reverse direction torque in the electromagnetic force generated in each magnetized portion due to the excitation also becomes weaker. Then, during energization, 12 of the 15 teeth are activated and an operating rate of 4/5 is obtained. When the three-phase drive method is used instead of this magnetic circuit, 10 of the 15 teeth are activated and the operating ratio is 2/3, so the magnetic circuit of FIG. Can generate a rotation torque comparable to that of the conventional three-phase bipolar.

The three embodiments of the present invention having the magnetic circuit having the basic structure of 5 slots and 4 poles in which the easy axis of magnetization is introduced into the stator and the direction of the easy axis of magnetization is appropriately selected have been described above. The application range of the present invention is not limited to the configuration of each embodiment, and can be widely applied to various motors and drive circuits using a directional stator without departing from the technical basis thereof. For example, the combination of the magnetized portions of the stator tip and the magnet having such a high operation ratio is not limited to 5: 4, and various combinations may be used within the range where the non-energization torque becomes zero. it can. Further, the exciting coil is half magnetized and half magnetized, but the ratio of the two can be set arbitrarily. In addition, a lamination stator having different directivity or a mixture of directivity and non-directionality, a multidirectional stator such as bidirectional, a magnetic circuit in which the number of poles and the number of slots are changed within the range in which the effect of the present invention can be obtained, An inductor motor or the like used by molding a single plate instead of the laminated core can be used.

Although all of the embodiments of the present invention utilize the directionality of the stator core, similar effects can be obtained when the magnet is anisotropic instead of the stator. For example, if the magnetization waveform of an isotropic magnet is asymmetrical with respect to the rotation direction, such as a sawtooth shape, and if it is attached as a plurality of magnet pieces with different orientation directions using an anisotropic material, the orientation direction should be tilted from the radial direction. In this case, the magnet is a magnet in which a plurality of orientation directions are mixed. Furthermore, there is a case where the directionality of the soft magnetic material and the anisotropy of the hard magnetic material are synergistic.

In addition, the starting effect according to the present invention can be applied to the case where it is used only at the time of starting and the rotation is continued by a three-phase drive circuit or other method. Further, the torque increasing effect according to the present invention can be selectively applied to a magnetic circuit in which a magnet is an inner rotor type, a motor in which a hard magnetic body is stationary and a soft magnetic body is rotated, and the like.

[0054]

According to the present invention, since the anisotropic magnetic field is introduced into the magnet motor, and by providing the drive circuit suitable for utilizing the generation of the anisotropic magnetic field, the mechanical shape of the magnetic circuit is improved. By using a purely electromagnetic method, it is possible to eliminate the starting dead point that is inevitably generated in the conventional magnetic circuit without applying any mechanical deformation.

According to the present invention, in the magnetic circuit configuration in which the non-energized cogging torque is not generated, the torque output exceeding the conventional three-phase bipolar system can be obtained by relatively reducing the ratio of the pause tips. Further, this characteristic makes it possible to use a magnet material having a low maximum magnetic flux density. As a result, it was possible to obtain high motor efficiency while reducing torque ripple, vibration, and noise.

According to the present invention, not only the number of magnetic sensors used can be reduced, but also a simple drive circuit such as single-phase or two-phase can be used, and the number of semiconductor elements can be reduced. At the same time, the motor structure can be simplified, and a compact, simple, and low-cost magnet motor can be provided.

According to the present invention, by introducing the directionality into the static or dynamic magnetic flux distribution, only one Hall sensor can be provided, and the problems associated with the characteristic variations of a plurality of sensors can be eliminated. it can.

According to the present invention, a sensorless motor having a simple structure can be constructed by introducing directionality into a static or dynamic magnetic flux distribution and providing a sensor coil in a part of the stator teeth.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic circuit of a first embodiment of a magnet motor according to the present invention.

FIG. 2 is a sectional view of a magnetic circuit of a conventional three-phase motor.

FIG. 3 shows aspects of non-energized torque and energized torque generated in each magnet pole in a conventional three-phase motor drive.

FIG. 4 shows aspects of non-energized torque and energized torque generated in each magnet pole in the first embodiment.

FIG. 5 is a block diagram of a drive circuit suitable for the magnet motor of the present invention.

FIG. 6 is a diagram for explaining a starting characteristic of the magnet motor of the present invention.

FIG. 7 shows aspects of non-energized torque and energized torque generated in each magnet pole in the second embodiment of the magnet motor of the present invention.

FIG. 8 shows a cross section of a magnetic circuit of a third embodiment of the magnet motor of the present invention.

[Explanation of symbols]

 1 Rotor Magnet 2 Stator 2a Stator Teeth 2p Directional Stator Magnetizing Easy Axis 3 Excitation Coil 4 Air Gap 5 Hall Sensor 51 Sensor Coil 6a Semiconductor Switch

Claims (9)

[Claims] 1. A rotor having a rotating shaft, a ring-shaped hard magnetic body having a plurality of magnetic poles on a circumferential end surface, a plurality of teeth and a soft magnetic body having a stator tip facing the magnetic poles at the circumferential end surface, In a magnet motor having an exciting coil wound around a tooth, means for detecting the position of the magnetic pole, and a drive circuit for energizing the coil, the relative positional relationship between the plurality of tips and the magnetic pole is determined by a combination of the two. A tip having the above winding is selected in addition to a combination in which the axial torque obtained by accumulating the non-energized partial torques generated in the individual tips is almost zero, and the teeth having the excitation coil and those not having the excitation coil are mixed. The relative positional relationship of the magnetic poles reduces the reverse torque component in the partial torque generated in each tip during energization and excitation. A magnet motor characterized by being selected as follows. 2. The angle occupied by the plurality of teeth and tip widths in the rotation circumference, or the circumference angle of the magnetic poles includes a plurality of values, and the winding position, the polarity and the number of turns of the exciting coil depend on the energization. Claim 1 wherein the combination is selected so as to reduce the partial reverse torque.
Item magnet motor. 3. The plurality of teeth are stator teeth having a unit number of 5, and the magnetized portion is a magnetized portion of a rotor magnet having a unit of 4 poles.
Winding is applied to four teeth in the book, and at least one of the unit teeth or magnetic poles has a uniform circumferential angle, and these unit teeth are repeated to form 10 teeth (or slots) 8 poles, 15 A magnetic circuit is configured as a slot 12 pole or the like, and each coil is connected to two terminals and connected to a single-phase bipolar or two-phase unipolar drive circuit, and the drive circuit energizes and excites the current. The magnet motor of the first and second terms. 4. The soft magnetic material or the hard magnetic material is directional in at least a part thereof, and the angle formed by the central axis of each tooth and the easy magnetization axis of the material is made different by individual teeth, When the coil is de-energized, the magnetic flux supplied from the hard magnetic material to the tip is unevenly distributed, thereby supplying an interlinking magnetic field to the magnetic pole detection means and starting the energization of the coil with its detection output. The magnet motor according to any one of claims 1 to 4, wherein the rotation of the rotor is started by an electromagnetic force generated between the magnetic pole and the tip. 5. The drive circuit includes means for reversing the energizing direction of the exciting current for a certain period at the time of starting,
By exciting the teeth in the reverse direction for a short time, axial torques having different phases are generated between the forward direction energization and the reverse direction energization due to the directionality of the easy axis of magnetization with respect to the rotation angle of the rotor. 3. A starter circuit is used, wherein during a period when the axial torque due to energization in one direction corresponds to zero cross or a low value, the other is used for a period during which axial torque due to energization with different phases is generated. To the single-phase magnet motor of the fourth item. 6. The magnetic flux detecting means is a Hall element, and based on a phase difference between the easy axis of magnetization and the induced magnetic flux of the exciting winding changing in accordance with a circumferential angle, the magnetic flux detecting means detects the two directions of the forward and reverse directions. The Hall element is arranged at a position where the phase difference of the shaft torque generated by energization is an electrical angle of about 90 °, and the energization direction is reversed for a short time at the time of start-up, so that the shaft torque that energizes in one direction is generated. The magnet motor according to any one of claims 1 to 5, wherein the rotation of the rotor is started by using a shaft torque having a large amplitude due to the energization of the other, when is equal to zero or a low value. 7. The magnetic flux detecting means is a coil wound around the non-winding tooth, and the magnetic flux interlinking with the coil is guided by the easy axis of magnetization and is inclined from the radial direction. The rotation direction of the rotor is identified based on the induced voltage of the coil being different depending on the rotation direction, and when the generated axial torque corresponds to zero or a low value at the time of starting, the interlinkage magnetic flux depends on the other conduction direction. The magnet motor according to any one of claims 1 to 5, wherein the rotation of the rotor is started by using torques having different phases. 8. The inversion period of the polarity recognition of the starter circuit,
The reverse excitation period is matched with a period substantially corresponding to a mechanical resonance frequency of the motor and the load, and the setting of the specific reversal period is canceled after starting. Item magnet motor. 9. The material of the stator is non-directional, an auxiliary winding or other starting means is used, and after starting the motor, by satisfying the requirements for the teeth and magnetic poles described above, 2. The magnet motor according to claim 1, wherein the ratio of the number of non-excited teeth to the total number of teeth in a certain period is reduced.