JP2004222460A - Synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synchronous motor wherein production of electromagnetic noise during starting operation is suppressed and transition from starting operation to synchronous operation can be carried out with reliability. <P>SOLUTION: A microcomputer 22 turns off triacs SW1 and SW2 to interrupt a synchronous operation circuit 21. Further, the microcomputer controls first to fourth transistors 16 to 19, and causes a rectification bridge circuit 20 to carry out full-wave rectification to perform starting operation. When the number of revolutions of a permanent-magnet rotor 5, detected by an optical sensor 12, reaches close to the number of synchronous revolutions with respect to the power supply frequency detected by a power supply frequency detecting unit 24, the microcomputer turns off the first to fourth transistors 16 to 19 and turns on the triacs SW1 and SW2. Thereby, the microcomputer attempts switching operation to switch from a starting operation circuit 14 to the synchronous operation circuit 21, and thus carries out control so as to transition to synchronous operation. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a synchronous motor.
[0002]
[Prior art]
In recent years, for example, OA equipment is equipped with a DC or AC fan motor for cooling, and a two-pole or four-pole AC fan motor is suitably used particularly for equipment requiring a high rotation speed.
[0003]
The inventor has already developed a highly reliable small synchronous motor capable of reliably switching from start-up operation to synchronous operation (see Patent Document 1). In this synchronous motor, of the rectified current flowing through a part of the armature coil of the start-up operation circuit, the inverted input on the negative side, which has been subjected to full-wave rectification, is subjected to a chopper operation by the control circuit to suppress the conduction range. Thus, the synchronization pull-in operation is reliably performed.
[0004]
[Patent Document 1]
Japanese Patent No. 3050851
[Problems to be solved by the invention]
In the synchronous motor disclosed in Patent Document 1 described above, in the start-up operation, the control circuit performs a chopper operation when the energizing direction is switched according to the rotation angle of the permanent magnet rotor and when the energizing range is narrowed. Electromagnetic noise is generated each time the current direction is switched (switched) due to the chopper operation. Even in a small synchronous motor having a relatively low output level of about 5 W to 10 W, the above-described electromagnetic noise may affect the signal lines of the wiring circuit.
[0006]
The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a synchronous motor capable of suppressing the occurrence of electromagnetic noise in the start-up operation and reliably switching from the start-up operation to the synchronous operation. To provide.
[0007]
[Means for Solving the Problems]
The present invention has the following configuration to achieve the above object.
That is, in a synchronous motor having a permanent magnet rotor provided rotatably about an output shaft in a housing and a stator having an armature coil wound around a stator core, an A coil and a B coil connected in series are provided. The armature coil including two coil segments having coils, first detection means for detecting a rotation speed and a magnetic pole position of the permanent magnet rotor, second detection means for detecting a frequency of an AC power supply, An AC current supplied from an AC power supply is rectified by a rectifier bridge circuit, and the direction of the rectified current is switched by a switching means in accordance with a rotation angle of the permanent magnet rotor to flow through an A coil of the armature coils. A starting operation circuit for starting and operating the permanent magnet rotor as a DC brushless motor; an AC power source; an A coil; and a B coil. Are connected in series, a synchronous operation circuit that synchronously operates the permanent magnet rotor as an AC synchronous motor, and an operation changeover switch that is provided between the AC power supply and the armature coil and that intermittently operates the synchronous operation circuit. And turning off the operation changeover switch to shut off the synchronous operation circuit and controlling the switching means to perform a start-up operation by performing full-wave rectification through a rectification bridge circuit and detected by the first detection means. When the rotation speed of the permanent magnet rotor reaches near the synchronous rotation speed with respect to the power supply frequency detected by the second detection means, all the switching means are turned off and the operation changeover switch is turned on to start up. A controller that controls the switching operation to switch from the operation circuit to the synchronous operation circuit until the transition to synchronous operation is repeated. Characterized by comprising and.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In the present embodiment, description will be made using a two-pole synchronous motor among synchronous motors.
FIG. 1 is an explanatory diagram of a starting operation circuit and a synchronous operation circuit of a two-pole synchronous motor. FIGS. 2A and 2B are external views of a permanent magnet rotor provided in a housing of the two-pole synchronous motor and a two-pole synchronous motor. 3 (a) to 3 (d) are front sectional explanatory views of a two-pole synchronous motor, an internal view of an upper housing, a bottom view, and a top view of a stator coil, and FIG. 4 (a) is a power supply AC waveform. 4 (b) is a full-wave rectified waveform, FIG. 4 (c) is a graph showing a rotation start-up waveform, FIG. 5 is a graph showing the relationship between the number of retries and the synchronization pull-in rate, and FIGS. FIG. 3B is an explanatory front view of a two-pole synchronous motor and a top view of a stator coil according to another example.
[0009]
First, the overall configuration of the two-pole synchronous motor will be described with reference to FIGS. In FIG. 2A, reference numeral 1 denotes a housing body that houses the rotor and the stator. The upper and lower portions of the housing body 1 are covered by an upper housing 2 and a lower housing 3. A permanent magnet rotor 5 is rotatably built in the housing body 1 around the output shaft 4. The output shaft 4 is rotatably supported by bearings 6 and 7 in the upper housing 2 and the lower housing 3. As the bearings 6 and 7, a non-magnetic material, for example, stainless steel is preferably used in consideration of disturbance of a magnetic field formed in the armature coil. Further, as shown in FIG. 3C, a wiring hole 3a for wiring to an armature coil 9 described later is formed in the lower housing 3.
[0010]
In the permanent magnet rotor 5, a link-shaped magnet 5b magnetized at approximately 180 ° at each of N and S poles is held on the inner wall of a cylindrical rotor yoke 5a. The permanent magnet rotor 5 starts rotating about the output shaft 4 by repulsion from a stator magnetic pole formed by energizing the armature coil. As the magnet 5b, for example, ferrite, a rubber magnet, a plastic magnet, samarium cobalt, a rare earth magnet, neodymium boron, or the like can be manufactured at low cost.
[0011]
In FIG. 3A, a stator 10 having an armature coil 9 in which an A coil and a B coil are wound in series around a stator core 8 is built in a space surrounded by a permanent magnet rotor 5. . As shown in FIG. 3D, the stator core 8 includes a main core 8a and an auxiliary core 8b extending around the main core 8a in a direction opposite to the rotation direction of the permanent magnet rotor 5. The magnetic permeability of the main core 8a is designed to be higher than that of the auxiliary core 8b. The main core 8a is preferably a laminated core made of a silicon steel plate, and the auxiliary core 8b is made of an SPC material (cold rolled steel plate). ) Is preferably used. The permanent magnet rotor 5 stops at a position where the magnetic poles of the magnetic poles of the main core 8a and the auxiliary core 8b are minimized (that is, a position shifted toward the auxiliary core 8b from a position facing the main core 8a). . Therefore, the dead center of the torque at the time of startup can be eliminated, and the rotation directionality of the permanent magnet rotor 5 at the time of startup can be stabilized.
[0012]
Further, the stator core 8 is fitted integrally with the bobbin 11, and the armature coil 9 is continuously wound around the bobbin 11 without being divided for each of the A coil and the B coil. As described above, since the core is wound with a large core area secured to the hobbin 11 to increase the space factor, the number of windings of the armature coil 9 is increased as compared with a 2-pole, 3-slot type motor. It can contribute to improvement of the output efficiency of the motor.
[0013]
2A and 3A, an optical sensor 12 is provided in the upper housing 2 as first detecting means for detecting the rotation speed and the magnetic pole position of the permanent magnet rotor 5. The optical sensor 12 includes, for example, a rotating disk in which a light detecting element 12a having a light source for light projection and a light receiving element, and a light shielding portion 13a and a light transmitting portion 13b are formed by 180 ° according to the magnetic pole position of the magnet 5b. 13 is equipped. The rotating disk 13 is mounted integrally with the permanent magnet rotor 5 and rotates integrally about the output shaft 4 (see FIG. 3B). The optical sensor 12 detects the rotation speed and the magnetic pole position of the permanent magnet rotor 5 by the rotating disk 13. The light detection element 12a generates a pulse corresponding to the rotation speed, and the control means described later controls the magnetic pole position according to the magnetic pole position. Switching control of the starting operation circuit 14 is performed at a predetermined timing. As shown in FIGS. 2A and 2B, the light detecting element 12a is fixed to the inner wall of the upper housing 2 by screwing.
The optical sensor 12 is not limited to the light transmission type, but may be a reflection type sensor. Further, as the other rotation speed detecting means of the optical sensor 12, various types such as a magnetic sensor using a Hall element, a magnetoresistive element, a coil, a method by high-frequency induction, a method by a capacitance change, and the like can be applied.
[0014]
Next, the configurations of a start-up operation circuit for starting and operating a two-pole synchronous motor, a synchronous operation circuit, and a control means for switching-controlling these circuits will be described with reference to FIG.
In FIG. 1, a start-up operation circuit 14 rectifies an AC current supplied from a single-phase AC power supply 15 by a rectifying bridge circuit 20, and switches the direction of the rectified current according to the rotation angle of the permanent magnet rotor 5 by a switching means. Then, the permanent magnet rotor 5 is started up as a DC brushless motor by flowing through the A coil of the armature coil. In the synchronous operation circuit 21, the single-phase AC power supply 15, the A coil and the B coil are connected in series, and the synchronous operation is performed using the permanent magnet rotor 5 as an AC synchronous motor. Triacs SW1 and SW2 are provided between the single-phase AC power supply 15 and the A and B coils as operation changeover switches, respectively. The triacs SW1 and SW2 are turned on / off by applying a gate pulse regardless of the polarity of the alternating current, and the connection is switched to the start-up operation circuit 14 or the synchronous operation circuit 21.
[0015]
In FIG. 1, first and second transistors 16 and 17 are respectively connected in series as switching means between the A coil and the rectifying bridge circuit 20. Third and fourth transistors 18 and 19 are connected in series as switching means between the A coil and the rectifying bridge circuit 20.
[0016]
Reference numeral 22 denotes a microcomputer as control means, which controls the amount and direction of current flowing through the start-up operation circuit 14 by switching control in the start-up operation, and controls the operation of the operation changeover switch when shifting from the start-up operation to the synchronous operation. I do. 23 is a low voltage power supply for driving the microcomputer.
[0017]
The microcomputer 22 turns off the triacs SW1 and SW2 to shut off the synchronous operation circuit 21 and controls the first to fourth transistors 16 to 19 to perform a start-up operation. At this time, the alternating current supplied from the single-phase AC power supply 15 is subjected to full-wave rectification through the rectifying bridge circuit to perform a start-up operation, and the rotation speed of the permanent magnet rotor 5 detected by the optical sensor 12 is determined by the second detection. When the power supply frequency detected by the power supply frequency detection unit 24 reaches near the synchronous rotation speed, the first to fourth transistors 16 to 19 are turned off, and the triacs SW1 and SW2 are turned on to start up. Control is performed such that the switching operation of switching from the operation circuit 14 to the synchronous operation circuit 21 is repeatedly attempted until the operation shifts to the synchronous operation.
[0018]
More specifically, referring to FIGS. 1 and 4, the microcomputer 22 detects the frequency of the AC power supply 15 by the power supply frequency detection unit 24 as the second detection means and inputs the frequency to the input terminal IN1. (See FIG. 4 (a) for the AC power supply waveform.) Further, the rotation speed and the magnetic pole position of the permanent magnet rotor 5 are detected by the optical sensor 12 and input to the input terminal IN2.
[0019]
Further, a switching signal to the triacs SW1 and SW2 is output from the output terminal OUT1, and the first and second transistors 16, 17 and the third and fourth transistors 18, 19 are turned on / off from the output terminal OUT2 and the output terminal OUT3, respectively. An output signal is output for the purpose. The microcomputer 22 outputs the base current from the output terminal OUT2 in the rotation angle range of 0 ° to 180 ° in accordance with the timing of the magnetic pole position of the permanent magnet rotor 5 detected by the optical sensor 12, and outputs the first and second signals. Only the two transistors 16 and 17 are turned ON (at this time, a rectified current indicated by a solid arrow {circle around (1)} flows through the start-up operation circuit 14), and a base current is output from the output terminal OUT3 in a rotation angle range of 180 ° to 360 °. Only the third and fourth transistors 18 and 19 are turned ON (at this time, the rectification current indicated by the broken arrow {circle around (2)} flows in the start-up operation circuit 14), and the direction of the rectification current flowing through the A coil is switched by 180 ° (total). The wave rectification waveform is shown in FIG.
[0020]
When the rotation speed of the permanent magnet rotor 5 detected by the optical sensor 12 approaches the frequency of the AC power supply 15 detected by the power supply frequency detection unit 24, all the first to fourth transistors 16 to 19 are turned off, A switching signal for turning on the triacs SW1 and SW2 is output, and an alternating current indicated by a two-dot chain line arrow (3) flows through the synchronous operation circuit 21.
[0021]
Also, the microcomputer 22 does not perform the chopper operation (switching operation for narrowing the energization angle range) and performs only the energization direction in a range where the rectified current flowing through the A coil has an inverted waveform during one rotation of the permanent magnet rotor 5. Is controlled. Then, as the rotation speed of the permanent magnet rotor 5 increases, the motor is started up near the synchronous rotation speed in synchronization with the rotation angle of the permanent magnet rotor 5 (see FIG. 4C). When the optical sensor 12 detects that the permanent magnet rotor 5 has reached the vicinity of the synchronous rotation speed, the microcomputer 22 in FIG. 1 turns off all the first to fourth transistors 16 to 19 and then turns on the triacs SW1 and SW2. Then, the starting operation circuit 14 is switched to the synchronous operation circuit 21. At this time, an alternating current indicated by a double-pointed arrow (3) in FIG. 1 flows through the armature coil 9 in series with the A coil and the B coil, and the permanent magnet rotor is synchronized with the change of the magnetic pole of the armature coil 9. 5 rotates and is rotationally driven as an AC synchronous motor. Since the A coil and the B coil are connected in series to the armature coil 9, an AC current corresponding to a load sufficient to generate a torque required for the synchronous operation flows. As described above, the occurrence of electromagnetic noise can be suppressed by performing the start-up operation by reducing the chopper operation by the microcomputer 22. In order to prevent a short circuit in the first to fourth transistors 16 to 19, the first to fourth transistors 16 to 19 are turned off and then the triacs SW1 and SW2 are turned on.
[0022]
In the case where the synchronous motor loses synchronism with one synchronous pull-in operation without shifting to the synchronous operation, the microcomputer 22 temporarily stops the rotation speed of the permanent magnet rotor 5 from dropping to the predetermined value after the synchronous rotational shift. The operation is shifted to the start-up operation, and repetitive control (retry) is performed so as to shift to the synchronous operation again. FIG. 5 shows the relationship between the synchronization pull-in rate and the number of retries. When no retry is performed, the synchronization pull-in rate is 50%, but it has been found that, for example, after 4 retries, approximately 96.5% shift to synchronous operation. Also, by omitting the operation of narrowing the energization range by, for example, the inverted waveform side by the microcomputer 22 in the start-up operation by the chopper operation, the electromagnetic noise can be reduced to about 1/10 of that of the conventional two-pole synchronous motor with the output of about 5 W. Could be suppressed.
[0023]
If the two-pole synchronous motor is used, the microcomputer 22 turns off the triacs SW1 and SW2 to cut off the synchronous operation circuit 21, and controls the first to fourth transistors 16 to 19 to switch the rectifier bridge circuit 20. When the start-up operation is performed by applying full-wave rectification and the rotation speed of the permanent magnet rotor 5 detected by the optical sensor 12 reaches near the synchronous rotation speed with respect to the power supply frequency detected by the power supply frequency detection unit 24, By turning off the first to fourth transistors 16 to 19 and turning on the triacs SW1 and SW2, the switching operation for switching from the start-up operation circuit 14 to the synchronous operation circuit 21 is controlled so as to be repeatedly attempted until the operation shifts to the synchronous operation. Reduces the occurrence of electromagnetic noise by reducing the chopper operation during start-up operation, and allows for more retries It is possible to provide a controllable synchronous motor easily at least to a small which can perform synchronous pull Ri.
[0024]
Another example of the synchronous motor will be described with reference to FIG. Although not limited to the two-pole synchronous motor, as shown in FIG. 6A, the permanent magnet rotor 5 has one end of the output shaft 4 linked to the rotor yoke 5a, and the rotor yoke receiving member 38 linked to the rotor yoke 5a. ing. In the stator 10, the stator core 8 is fixed to a stator fixing member 39, and the stator fixing member 39 is fitted in the lower housing 3. The permanent magnet rotor 5 is rotatable via a bearing 6 provided on the upper housing 2 and a bearing 7 provided between the rotor yoke receiving member 38 and the lower housing 3.
[0025]
As shown in FIG. 6B, an A coil is attached to a bobbin 11 having a core 11 a attached to the stator core 8 and extending in a direction orthogonal to the rotation center of the permanent magnet rotor 5 and flanges 11 b at both ends of the core 11 a. And the B coil are wound continuously.
Therefore, there is no useless space for the output shaft 4 to pass through the stator core 8, so that the winding core area can be enlarged to further increase the space factor and increase the output efficiency of the motor.
[0026]
The synchronous motor according to the present invention can be applied not only to a two-pole synchronous motor but also to a four-pole synchronous motor and an eight-pole synchronous motor. Further, the synchronous motor described above is not limited to the outer rotor type, and may be an inner rotor type.
Further, the synchronous motor has a microcomputer 22 for driving and controlling the motor, or a part of a control circuit (AC power supply, (Including a start-up operation circuit, a synchronous operation circuit, and the like).
In addition, the present invention can be widely applied to a synchronous motor generally called an inductor type, and a planar opposed type synchronous motor in which a flat-plate-like magnet and a coil are opposed on a disk.
In addition, the synchronous motor according to the present invention includes a thermal fuse or a bimetal in a circuit portion which is always energized during operation, in order to guarantee safety at the time of overload, like an induction motor generally used conventionally. A high temperature detection switch of the type can also be incorporated.
Further, the armature coil 9 is not limited to the one divided into the A coil and the B coil, and may be a single coil if power consumption efficiency is ignored. Can be done.
[0027]
【The invention's effect】
When the synchronous motor of the present invention is used, the control means turns off the operation changeover switch to cut off the synchronous operation circuit, controls the switching means, performs the full-wave rectification through the rectification bridge circuit, and performs the start-up operation. When the rotational speed of the permanent magnet rotor detected by the first detecting means reaches near the synchronous rotational speed with respect to the power supply frequency detected by the second detecting means, the switching means is turned off and the operation changeover switch is turned on. By doing so, the switching operation to switch from the start-up operation circuit to the synchronous operation circuit is controlled so as to repeatedly try until the operation shifts to the synchronous operation, so that the chopper operation in the start-up operation operation is reduced, the occurrence of electromagnetic noise is suppressed, and the number of retries is possible. To provide a small and easily controllable synchronous motor capable of performing synchronous pull-in with as little as possible. It can be.
The A coil and the B coil are continuously wound on a bobbin having a core mounted on a stator core and extending in a direction perpendicular to the rotation center of the permanent magnet rotor and flanges at both ends of the core. In such a case, no wasteful space is generated by the output shaft through which the stator core is inserted, so that the core area can be increased to increase the space factor and increase the output efficiency of the motor.
In addition, since the synchronous motor performs the transition operation from the start operation to the synchronous operation under the control of the microcomputer, even if the power supply frequency changes to 50 Hz, 60 Hz, 100 Hz, etc., the same operation is performed without changing the detailed mechanical design. Since a synchronous motor can be used, an extremely versatile synchronous motor can be provided.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a starting operation circuit and a synchronous operation circuit of a two-pole synchronous motor.
FIG. 2 is an external view of a permanent magnet rotor installed in a housing of the two-pole synchronous motor and a top view of the two-pole synchronous motor.
FIG. 3 is an explanatory front view of a two-pole synchronous motor, an internal view of an upper housing, a bottom view, and a top view of a stator coil.
FIG. 4 is a graph showing a power supply AC waveform, a full-wave rectified waveform, and a rotation start waveform.
FIG. 5 is a graph showing the relationship between the number of retries and the synchronization pull-in rate.
FIG. 6 is an explanatory front view of a two-pole synchronous motor and a top view of a stator coil according to another example.
[Explanation of symbols]
Reference Signs List 1 housing body 2 upper housing 3 lower housing 3a wiring hole 4 output shaft 5 permanent magnet rotor 5a rotor yoke 5b magnet 6, 7 bearing bearing 8 stator core 8a main core 8b auxiliary core 9 armature coil 10 stator 11 bobbin 12 optical sensor 12a light Detecting element 13 Rotating disk 13a Light shielding unit 13b Light transmitting unit 14 Start-up operation circuit 15 AC power supply 16 First transistor 17 Second transistor 18 Third transistor 19 Fourth transistor 20 Rectifier bridge circuit 21 Synchronous operation circuit 22 Microcomputer 23 Low voltage Power supply 24 Power supply frequency detector 38 Rotor yoke receiving member 39 Stator fixing member

Claims (4)

In a synchronous motor having a permanent magnet rotor rotatably provided around an output shaft in a housing and a stator having an armature coil wound around a stator core,
Said armature coil comprising two coil segments having an A coil and a B coil connected in series;
First detection means for detecting the rotation speed and the magnetic pole position of the permanent magnet rotor;
Second detection means for detecting the frequency of the AC power supply;
Rectifying an alternating current supplied from the alternating current power supply by a rectifying bridge circuit, and switching the direction of the rectified current according to a rotation angle of the permanent magnet rotor by a switching means to flow the current to the A coil of the armature coils. A start-up operation circuit for starting up the permanent magnet rotor as a DC brushless motor,
A synchronous operation circuit in which the AC power supply, the A coil and the B coil are connected in series, and the permanent magnet rotor is synchronously operated as an AC synchronous motor;
An operation changeover switch provided between the AC power supply and the armature coil, for intermittently operating the synchronous operation circuit,
By turning off the operation changeover switch to shut off the synchronous operation circuit and controlling the switching means, the start-up operation is performed by performing full-wave rectification through the rectification bridge circuit, and the permanent operation detected by the first detection means is performed. When the rotation speed of the magnet rotor reaches the vicinity of the synchronous rotation speed with respect to the power supply frequency detected by the second detection means, the start-up operation circuit is turned off by turning off all the switching means and turning on the operation changeover switch. Control means for repeatedly performing a switching operation for switching from a synchronous operation circuit to a synchronous operation circuit until a transition to synchronous operation is performed. When the control means shifts from the start-up operation to the synchronous operation, the control means switches off a switching means for supplying a rectified current to the start-up operation circuit, and then controls the operation changeover switch to shift to the synchronous operation. The synchronous motor according to claim 1, wherein: The stator core is provided with an auxiliary core extending in a direction opposite to the rotation direction of the permanent magnet rotor on the main core, and is designed so that the magnetic permeability of the main core is larger than that of the auxiliary core. The synchronous motor according to claim 1 or 2, wherein: The stator is mounted on the stator core, and the armature coil is continuously wound around a bobbin having a core extending in a direction perpendicular to the rotation center of the permanent magnet rotor and flanges at both ends of the core. The synchronous motor according to claim 1, 2 or 3, wherein:

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