JP2002218691A - AC servo motor - Google Patents

Abstract

(57) Abstract: An AC servomotor capable of reducing switching noise of a power element by PWM control and reducing the capacitance of a switching noise suppressing capacitor. SOLUTION: A stator 2 in which a three-phase stator coil 5 for forming a rotating magnetic field is mounted on an inner peripheral surface of a stator core 4, and a plurality of permanent magnets 10 on an outer peripheral surface of the rotor core 9. And a rotor 3 disposed so as to face the stator coil 5 with a gap therebetween, and the lead wire 5a of each phase of the stator coil 5 is connected to the stator core 4 A plurality of times around the yoke portion 4a to form a common mode choke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC servomotor used for FA and OA, and more particularly to a configuration of a stator coil thereof.

[0002]

2. Description of the Related Art Conventionally, servo amplifiers and inverters generally adjust motor current by PWM control of a DC voltage. FIG. 2 shows a block diagram of the PWM drive. In PWM control, a pulse-shaped leakage current flows due to the application of dV / dt during switching of the power element. Leakage current is the current flowing from the power supply to ground. It flows to the ground through a capacitor between each phase and FG (frame ground) 11. As shown in FIG. 2, the capacitor can be considered in three places. AC
The capacitor 12 is a capacitor for noise suppression inserted into the AC line, and the diode bridge 13 and the FG 1
1 consists of stray capacitances. The DC capacitor 14 is D
It is composed of a noise countermeasure capacitor inserted into the C line, and a stray capacitance between the power element 15 and the FG 11. The motor capacitor 16 is composed of a stray capacitance between the motor coil 17 and the FG 11. Noise synchronized with the switching frequency of the power element 15 is generated due to the leakage current of the motor capacitor 16. Conventionally, as described above, a capacitor is inserted in the AC or DC section or both of the servo amplifier to reduce this noise. are doing. Alternatively, in order to reduce the stray capacitance of the motor section, a technique of strengthening the insulation between the armature windings and the ground is used.

[0003]

However, such a conventional AC servomotor has the following problems. (1) When a capacitor is inserted between the power supply line of the servo amplifier and the FG, a leakage current of the power supply frequency occurs. Since the leakage current at the power supply frequency increases as the capacitance of the capacitor inserted between the power supply line and the FG increases, it is necessary to reduce the capacitance of the capacitor to reduce the leakage current at the power supply frequency. However, when the capacitance of the capacitor is small, noise due to switching cannot be reduced. (2) If the core insulation thickness is increased to reduce the capacitance between the stator coil of the motor and the frame,
Since the effective winding space is reduced, motor losses increase. The present invention has been made in order to solve such a problem, and it is possible to reduce the switching noise of a power element by PWM control and reduce the capacitance of a switching noise suppressing capacitor.
It is an object to provide a servomotor.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a stator having a three-phase stator coil for forming a rotating magnetic field mounted on an inner peripheral surface of a stator core. An AC servomotor having a plurality of permanent magnets mounted on the outer peripheral surface of the stator core and having a rotor arranged to face the stator coil via a gap, wherein each of the stator coils The lead wire of the phase is wound around the yoke portion of the stator core a plurality of times to form a common mode choke. By doing so, the current harmonic components of each phase due to switching of the power element cancel each other, and the leakage current can be reduced.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view of an AC servomotor showing an embodiment of the present invention. This embodiment shows an example of a three-phase, nine-slot, eight-pole slot-winding AC servomotor. In the figure, 1 is an AC servo motor 1
And a stator (armature) 2 and a rotor 3. 4
Is a stator core formed by laminating silicon steel plates, and comprises a cylindrical yoke portion 4a and a tooth portion 4b. The teeth 4a are arranged at equal intervals, and nine are integrally formed by an inner connecting portion. A three-phase stator coil 5 is wound around the teeth portion 4b in a concentrated winding. The stator coil 5 is wound around a bobbin (not shown) made of an insulating material a predetermined number of times, and is wound through the bobbin. And is attached to the taste part 4b. The teeth part 4b includes:
The stator core 4 is fixed to the inner peripheral surface of the yoke portion 4a by shrink fitting or the like, and integrally formed. Reference numeral 6 denotes a slot between the teeth portions 4b. 5a is a lead wire of the stator coil 5. Further, the stator core 4 is provided with three notches 7, and the lead wires 5 a of U, V, and W phases are turned several times so that a predetermined inductance is obtained in the notches 7, for example, It is wound toroidally for 3 turns. Since the notch 7 is located on the opposite surface to the center of the slot 6, the lead wire 5a is wound around the center of the slot 6 and the notch 7, and does not interfere with the stator coil 5. The inner peripheral portion of the stator core 4 is a part of a magnetic circuit of the motor, and requires a thickness t that does not saturate. Generally, this thickness is equal to the width of the teeth portion 4c. Since the depth of the notch 7 is set so as not to interfere with the thickness t,
It does not adversely affect the magnetic field. The rotor 3 is
The rotating shaft 8 is rotatably supported via a bearing (not shown), and the rotor core 9 is fitted and fixed to the rotating shaft 8.
And a permanent magnet 10 attached to the outer peripheral surface of the rotor core 9. In such a configuration, magnetic flux is generated on the inner peripheral surface of the stator core 4 and the cylindrical portion surrounded by the dotted line due to the armature current flowing through the lead wire 5a of each phase. Armature current consists of main component (signal wave component) and PWM
Although it is divided into the ripple current component (carrier component) due to driving, the magnetic flux due to the signal component cancels each other in each phase, and only the magnetic flux due to the carrier component is generated. The lead wire 5a functions as an inductance for the carrier component magnetic flux.
That is, since the lead wire 5a functions as a common mode choke, the carrier component of the armature current is attenuated, and the switching noise of the power element due to the PWM control can be reduced. As a result, the power line of the servo amplifier and F
The capacitance of the switching noise suppressing capacitor inserted between G can be reduced. Therefore, the size of the servo amplifier can be reduced, and the leakage current generated at the power supply frequency in the AC servomotor 1 can be reduced. It should be noted that the present invention is not limited to the three-phase, nine-slot, eight-pole specification slot-winding type AC servomotor described in the above embodiment, and can be applied to AC servomotors of other specifications. As long as the AC servomotor has a winding space in the center of the slot, it can be applied to, for example, a non-overlapping concentrated winding smooth armature winding type motor or a linear motor.

[0006]

As described above, the present invention has the following effects. (1) In the AC servomotor, the lead wire of the stator coil of each phase is wound around the yoke of the stator core a plurality of times to form a common mode choke, so that switching noise of the power element by PWM control can be reduced. Can be. (2) According to (1) above, the power supply line of the servo amplifier and FG
The capacitance of the switching noise suppressing capacitor inserted therebetween can be reduced. Therefore, the size of the servo amplifier can be reduced, and the leakage current generated at the power supply frequency can be reduced.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an AC servomotor according to an embodiment of the present invention.

FIG. 2 is a block diagram of PWM driving in the related art.

[Explanation of symbols]

 1 AC servo motor, 2 stator, 3 rotor, 4 stator core, 4a yoke part, 4b teeth part, 5 stator coil, 5a lead wire, 6 slot, 7 notch, 8 rotating shaft, 9 rotor core , 10 permanent magnet, 11 frame ground, 12 AC part capacitor, 13 diode bridge, 14 DC part capacitor, 15 power element, 16 motor part capacitor, 17 motor coil

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H002 AA09 AB04 AB06 AE08 5H603 AA01 BB01 BB07 BB09 BB12 CA01 CA05 CB04 CC07 CC11 CC17 CD21 CD22 5H611 AA03 BB01 BB06 PP02 QQ06 QQ07 SS03 TT01 TT05 UA03

Claims (2)

[Claims] A stator for forming a rotating magnetic field is formed on an inner surface of a stator core.
A stator having phase stator coils mounted thereon, and a rotor having a plurality of permanent magnets mounted on the outer peripheral surface of a rotor core and arranged so as to face the stator coils via a gap. An AC servomotor comprising: a common mode choke, wherein a lead wire of each phase of the stator coil is wound around the yoke portion of the stator core a plurality of times. 2. A lead wire for each phase of the stator coil,
2. The AC servomotor according to claim 1, wherein the stator core is wound around a magnetic circuit portion of a yoke portion of the stator core.