JPH05316783A - Synchronous motor - Google Patents

Abstract

PURPOSE:To facilitate control of r.p.m. and motor output or torque by providing a stator wound in two-phase, a rotor configured substantially in salient pole, and two controllers. CONSTITUTION:Current determining circuit 109 for winding A determines current command m1 for winding A based on the deviation e1 of r.p.m. A first control section 111 produces a signal, converted into a current corresponding to a rotor position R, based on the current command signal m1. The signal thus produced is then compared with a current value detected through a first current detector 123 and a control signal, e.g. a PWM control signal, for a first inverter circuit is produced based on the difference. Similarly, a current determining circuit 129 for winding B produces a current command signal m2 based on a deviation e2 of motor output and a second control section 131 produces a control signal for second inverter circuit based on a signal converted into a current corresponding to the rotor position R. Alternatively, r.p.m. and torque can be controlled simultaneously by identical manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for machine tools and the like, and further to a synchronous motor in which the rotational speed and output value or output torque of the motor are simultaneously controlled.

[0002]

2. Description of the Related Art Conventionally, a synchronous motor used in a machine tool or the like has a rotor and an armature (or a stator), which is composed of a permanent magnet or is wound with a coil to generate a direct current. Excited ones or salient pole shaped ones are used. Further, as the armature, a coil is wound in a single layer and the number of poles is 2, 4, 6, or the like. A two-phase or three-phase (normally three-phase) alternating current is used as the current for generating the rotating magnetic field.

However, the synchronous motor used for the spindle of the machine tool is required to control the output value as well as the rotational speed of the motor for the reason described below.

That is, in the case of a bottom milling machine that grinds a flat surface, for example, the end mill (cutting blade) is usually directly connected to the spindle motor. A constant peripheral speed and a constant cutting force, which are determined by the material and the like, are required. That is, when a large diameter end mill shown in FIG. 10 (A) is used, a large torque low speed rotation is performed, and when a small diameter end mill shown in FIG. Is desirable.

Further, it is desirable that the spindle motor for rotationally driving the spindle of the lathe should give a constant cutting force regardless of the machining radius. That is, as shown in FIG. 11, it is desirable to keep the cutting amount, that is, the cutting force constant, even when the machining radius becomes smaller as the cutting progresses, and therefore, the rotation speed of the motor is increased to It is desirable to keep the motor output constant.

As described above, the motor used for the spindle of the machine tool is required to have a control system for simultaneously controlling the rotational speed and the torque value or the rotational speed and the output value to predetermined values.

However, a conventional motor used for the spindle of a machine tool is a coil having a single layer winding, and is a motor made by controlling the phase, frequency, gain, etc. of the current flowing through the coil at the same time. is there. This control method is complicated and it is difficult to obtain a predetermined load characteristic.

The present invention is to solve the above-mentioned difficulty of control.

[0009]

As described above,
A coil of a synchronous motor has a problem that it is difficult to satisfy various characteristics required for a spindle motor of a machine tool at the same time because the method of controlling the current by a single layer winding is complicated.

[0010]

In order to solve the above problems, the synchronous motor of the present invention comprises a stator having windings A and B wound in two layers and a substantially salient pole. A rotor or a rotor having a constant magnetic pole direction, a power supply device for winding A, a first control device for controlling the rotation speed of the motor, and a power supply device for winding B, And a second control device for controlling the output value (or torque value) of the motor.

[0011]

The number of revolutions of the motor is controlled by detecting the number of revolutions of the motor and the position of the rotor by the first controller and controlling the current flowing through the winding A, and the output value (or torque value) of the motor is controlled. Is controlled by the second controller controlling the current flowing through the B winding, which changes the rotating magnetic field to perform a magnetizing action or a demagnetizing action.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a reaction synchronous motor will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the entire control system when the present invention is applied to a reaction synchronous motor.

The reaction synchronous motor is a kind of salient-pole type synchronous motor, which excites the rotor and operates only by the reaction torque. Further, as shown in FIG. 2, in the reaction synchronous motor, when a rotating magnetic field is generated by connecting, for example, a three-phase current to the stator winding, the magnetic resistance of the rotor differs depending on the angle, so that the direction in which the rotor protrudes. That is, the rotor is magnetized in the direction P of the polar axis having the smallest magnetic resistance.
Therefore, the rotor is rotated by the magnetized polar axis and the rotating magnetic field. In order to magnetize the rotor in a fixed direction (direction of the polar axis) as shown in the figure, not only when the rotor has a protruding cross-sectional shape as shown in FIG. However, the rotor may be configured such that the magnetic resistance differs depending on the direction due to different magnetic bodies. Further, a salient pole may be provided by providing an appropriate slit on the rotor.

In FIG. 1, the stator of the synchronous motor 101 has an A winding (UVW) and a B winding (u) as shown in FIG.
-Vw) is wound in two layers, and the control of the rotating magnetic field is performed by the control of these combined vectors. A control block diagram for controlling the rotating magnetic field will be described below.

In FIG. 1, the first control device for supplying the current I _A to the winding A is constructed as follows. That is, the rotation speed command device 151 that specifies the rotation speed N of the synchronous motor 101, the first detector 103 that detects the rotation speed N of the motor 101, and the second detector 105 that detects the position R of the rotor. Is compared with the rotation speed N ^* of the rotation speed commander and the rotation speed N of the motor to obtain the deviation e _1.
7, an A winding current determination circuit 109 that determines the current command m ₁ of the A winding based on the deviation e ₁ , a first inverter 113 that causes a predetermined current to flow through the A winding, and a current command m ₁ . A
The first control unit 111 determines a control signal M ₁ for controlling the first inverter based on the current I ₁ flowing in the winding and the position R of the rotor.

The current I ₁ flowing through the winding A is detected by the first current detector 123. Further, the A winding current determination circuit 109 increases the current I _A flowing through the A winding when the deviation e ₁ is positive, that is, when the actual motor rotation speed N is smaller than the specified rotation speed N ^*. Then, the current command signal m ₁ is determined. In the opposite case, the current I _A is decreased. The first control unit 111 creates a signal converted into a current corresponding to the rotor position R based on the current command signal m ₁ and compares this signal value with the current value of the first current detector 123 to determine the deviation. Based on the control signal of the first inverter circuit, for example, P
Generate a WM control signal. When using a three-phase current for a synchronous motor, three Ps with different phases by 120 degrees are used.
A WM control signal is generated.

Further, the number of rotations of the motor and the position of the rotor are detected by a known conventional technique such as a rotary encoder or a resolver.

In FIG. 1, the second controller for supplying the current I _B to the winding B is constructed as follows. That is,
An output command device 153 that specifies an output value of the motor, a first detector 103, a second detector 105, and a first current detector 12
The output evaluator circuit 121 for calculating the output value of the motor on the basis of each data of 3 and the second current detector 125 is compared with the specified output P ^* and the calculated output value, and the deviation e
_{A second} deviation detector 127 for determining ₂ , a B winding current determination circuit 129 for generating a current command signal m ₂ for determining the current of the B winding based on the deviation e ₂ , and a B winding A second inverter 133 for flowing a predetermined current, the current command signal m ₂ , and a current I flowing through the rotor position R and B windings.
The second control unit 131 outputs a control signal M ₂ for controlling the second inverter 133 based on the data of ₂ .

The current I ₂ flowing through the B winding is detected by the second current detector 125. Further, the B winding current determination circuit 129, when the deviation e ₂ is positive, that is, when the calculated output value is smaller than the designated output value P ^* , the B winding current is increased in the direction of increasing the B magnetic field. Issue a command m ₂ to increase the current in the line. That is, as shown in FIG. 2, the direction of the magnetized magnetic poles of the rotor is P, the direction of the combined rotating magnetic field generated by the currents I _A and I _{B of} the A winding and B winding is Φ ₀ . At this time, the current I _B of the B winding increases in the direction in which the load angle δ increases.

This is because the rotational torque is increased by moving the changing direction of the alternating current that causes the rotating magnetic field in the direction approaching the right angle with respect to the direction of the magnetic field vector of the magnetic pole. For this, as shown in FIG. 3, with respect to the direction of the rotating magnetic field .PHI _A by A winding current I _A, increasing the magnetic field .PHI _B by B winding current I _B in the positive direction shown combined magnetic field .PHI Move ₀ in the direction of phase advance. Also, the deviation e ₂
Is negative, increasing the magnetic field Φ _B in the negative direction,
Increase the B winding current I _B.

The second controller 131 produces a signal converted into a current corresponding to the rotor position R based on the current command signal m ₂ , and compares this signal value with the current value of the second current detector 125. Then, a control signal for the second inverter circuit, for example, a PWM control signal is generated based on the deviation. The control signal of the second inverter circuit is preferably configured so that the phase advance or delay of the current I _B of the second inverter is 90 degrees with respect to the current I _A flowing in the first inverter.
Also, 1 if three-phase current is used in the synchronous motor.
Three PWM control signals having different phases by 20 degrees are generated.

The rotation speed N ^* and the output value P ^* designated by the rotation speed commander 151 and the output commander 153 do not have to be constant, and may change according to time or conditions. For example, starting of the motor and the like can be performed by program control or sequence control.

FIG. 4 shows three-phase AC windings A and B
The figure shows an example in which two layers are wound around the armature core as a pole and 24 slots. In FIG. 4, 201 is an armature core and 203 is a rotor. 205 and 207 are windings wound in two layers, the A winding is shown by (U, V, W) and (U ', V', W '), and the B winding is ( u,
v, w) and (u ', v', w '). The winding method is a known method. Also, A winding and B
The windings may be insulated from each other by a material 211 having a large magnetic resistance as shown in FIG. 7 in order to reduce mutual interference.

FIG. 5 shows the phase relationship between the currents flowing in the coils U and u when the phase difference between the current in the A winding and the current in the B winding is 90 degrees.

FIG. 6 is an example showing the phase relationship of the currents flowing in the respective windings in the case of three-phase alternating current.

The number of rotations of the motor and the direction of the magnetic poles of the rotor can be detected by using a known conventional technique such as a rotary encoder or a resolver.

When the rotating magnetic field Φ _A is made larger than Φ _B , for example, the magnitude of the current │I _A │ flowing in the winding is increased to several times the magnitude │I _B │ of the current flowing in the B winding. In that case, the direction P of the magnetic poles in which the rotor is magnetized is almost equal to the current I.
_It is determined by the rotating magnetic field Φ _A generated by _A , and the current I _B of the B winding can be mainly used as a current for controlling the rotating magnetic field.

In the present embodiment, the phase difference between I _A and I _B is 90 degrees, but this is an arbitrary angle α (0 ° <α
<90 °). However, it is desirable to control the phase difference to be 90 degrees and to reduce mutual interference due to armature reaction and the like.

It is possible to calculate the output from the number of rotations of the motor, the position of the rotor, the currents I _A and I _B flowing through each winding, by a known conventional technique, or by preliminary experiments. is there.

In the present embodiment, the simultaneous control of the rotational speed and the output is performed, but the simultaneous control of the rotational speed and the torque can be performed by the same method.

8 and 9 show an embodiment in which the present invention is applied to a magnetic pole type synchronous motor using a permanent magnet. FIG. 8 shows the case of two poles, and FIG. 9 shows the case of four poles.

In FIG. 8, reference numeral 231 denotes a rotor, and permanent magnets 233 and 235 are fixed to the outside of the rotor. Two
Reference numeral 41 is an armature core, and the A winding wire 243 and the B winding wire 245 are wound in two layers on the armature core. If the current shown in the figure is flowing in the A and B windings, that is, if the B winding is A
When it is delayed by 90 degrees from the winding, the rotating magnetic field by the winding A is generated in the direction of the solid line in the figure, and the rotating magnetic field by the winding B is generated in the direction of the dotted line in the figure.

In the case of this embodiment, the direction of the magnetic poles of the rotor is mainly determined by the permanent magnets, and the rotational speed and the output of the motor are determined by the rotating magnetic field generated by the current flowing through the windings A and B. Also in the case of this embodiment, if the phase difference between the currents I _A and I _B is 90 degrees, the direction of the synthetic magnetic field can be easily controlled by controlling I _B, and the control of the load angle is also easy. Becomes Note that | I _A | and | I
_B | does not have to be particularly different, and may have the same size.

The control method of the magnetic pole type synchronous motor using the permanent magnet can be controlled by the same method as the control method of the reaction synchronous motor described above.

FIG. 9 shows a case where the number of poles is four, and the synchronous motor can be controlled by the above-described method as in the case of two poles.

In the above embodiments, only the rotary type synchronous motor has been described, but the present invention can also be applied to a linear synchronous motor.

[0038]

As described above, according to the present invention, it is possible to easily control the rotation speed and the motor output or the rotation speed and the torque. As a result, it is highly useful as a spindle motor for machine tools and the like, which requires constant output.

[Brief description of drawings]

FIG. 1 is a block diagram of a control system according to an embodiment of the present invention.

FIG. 2 shows a relationship between a magnetic pole direction of a rotor and a direction of a rotating magnetic field in a reaction motor.

FIG. 3 shows a relationship between a rotating magnetic field generated by an A winding and a magnetic field combined with a rotating magnetic field generated by a B winding.

FIG. 4 shows an embodiment in which the armature core is wound in two layers.

FIG. 5 shows the phase relationship of the currents of the U winding and the u winding when the phase difference between the A winding and the B winding is 90 degrees.

FIG. 6 shows a phase relationship between currents in the A winding and the B winding when a three-phase current is used.

FIG. 7 shows an example of insulating with a material having a large magnetic resistance in order to reduce the mutual influence of the A winding and the B winding.

FIG. 8 shows an example in which the present invention is applied to a synchronous motor using a permanent magnet. This is the case of two poles.

9 shows a case where the number of poles is 4 in FIG.

FIG. 10 shows a relationship between an end mill and a work piece.

FIG. 11 shows the relationship between the cutting process of the lathe and the machining radius.

[Explanation of symbols]

 101 Synchronous Motor 103 Rotation Speed Detector 105 Position Detector 109 A Winding Current Determining Circuit 111 First Control Unit 113 First Inverter 129 B Winding Current Determining Circuit 131 Second Control Unit 133 Second Inverter 301, 303, 321 Spindle 305,307 End mill 309,327 Work piece 323 Chuck 325 bytes

Claims (4)

[Claims] 1. A stator in which a winding A and a winding B are wound in two layers, and a rotor which is made substantially salient by a material having different magnetism or a rotor which is made salient by changing its shape. A power supply device for winding A, a first control device for controlling the number of rotations of the motor, and a power supply device for winding B, the output value (or torque value) of the motor A second control device for controlling the synchronous motor. 2. A stator in which a winding A and a winding B are wound in two layers, and a rotor to which a permanent magnet is attached for generating a field magnetic flux or a rotor in which a coil is passed and a current flows. , Winding A
A power supply device for controlling the number of rotations of the motor, and a power supply device for the winding B, a second control device for controlling the output value (or torque value) of the motor. A synchronous motor comprising a control device. 3. The second control device is constituted by a device for holding the phase difference between the current of the winding B and the current of the winding A at 90 degrees and controlling the magnitude of the gain. The synchronous motor according to claim 1 or 2, characterized in that 4. The first control device compares a rotation speed commander that specifies a rotation speed with a specified rotation speed and rotation speed data of a motor, and based on a deviation between the rotation speed commander and the rotation speed commander, a current command for the winding A is issued. A winding current determining circuit for determining, A winding current for supplying a predetermined current to the A winding based on the current command signal from the circuit, the current value data of the A winding, and the position data of the rotor of the motor And a second supply device,
Output command device that specifies the output value of the motor, A winding and B
Current data flowing in the winding and rotation speed data of the motor,
An output arithmetic circuit that calculates the output value of the motor based on the rotor position data is compared with the specified output value and the calculated output value, and the current command to be passed through the B winding is determined based on the deviation. B winding current determination circuit, B winding current supply for supplying a predetermined current to the B winding based on the current command signal from the circuit, the current value data of the B winding and the position data of the rotor of the motor The synchronous motor according to claim 3, wherein the synchronous motor comprises an apparatus.