JP2001352792A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise of a motor, prevent imperfect rotation, and improve operation quality remarkably. SOLUTION: In this motor 21, a capacitor 30 is connected in parallel with a part between a neutral point 29 of star-connected coils L1, L2, L3 and the ground potential.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor such as an AC motor or a brushless DC motor.

[0002]

2. Description of the Related Art FIG. 3 is a simplified cross-sectional view of a molded motor (hereinafter referred to as a motor) 1 having a structure serving as a basis of the present invention. FIG. 9 is a block diagram showing a schematic electric structure of the motor 1. is there. FIG. 3 is also referred to in the following related art section and also in the embodiment section of the invention described later.

Hereinafter, the configuration of the motor 1 will be described with reference to FIG.

A motor 1 includes a stator core (hereinafter, core) 2
The coil 3 is wound around, and is molded with an electrically insulating synthetic resin material to form a mold frame (hereinafter, frame) 4 made of the electrically insulating synthetic resin material. A bearing housing 6 configured as a part of the frame 4 is provided on one axial side of the stator 5, and a bearing 7 is fitted to the bearing housing 6. The motor 1 also includes a bearing 8 on the opposite side of the stator 5 in the axial direction, and rotatably supports a metal rotating shaft 10 included in the rotor 9. Further, on a side of the frame 4 opposite to the bearing housing 6, a bracket 11 made of a metal plate by, for example, pressing.
Is attached by a screw or the like, and the screw is screwed to a screw seat embedded in the frame 4. The bracket 11 holds the bearing 8. Also, frame 4
A wiring board 12 is embedded therein, and a connection of the coil 3, mounting of a Hall element, and a lead wire 14 drawn out through a bushing 13 are mounted on the wiring board 12. Further, the rotating shaft 10 is attached by, for example, press-fitting into a structure in which a conductive material such as a coil is mounted on the rotor core 15 after finishing the surface shape of the cylindrical metal rod by cutting. The child 9 is configured. Such a motor 1
In order to fix the bracket 11 by connecting it to the frame 4, in addition to the above-mentioned screw fixing, caulking using a rivet, or the bracket 11
Is pressed into the frame 4.

FIG. 9 is a block diagram showing an electrical configuration of a typical conventional motor 1 and a motor control device (hereinafter, a control device) 16. FIG. 10 (1) shows a neutral point 17 of the motor 1. FIG. 10B is a waveform diagram of the potential Vm, FIG. 10B is a waveform diagram of the current Im in the resistor R of the control device 1, and FIG.
(1) is an enlarged view of FIG. 10 (1), and FIG. 11 (2) is an enlarged view of FIG. 10 (2).

The control device 16 shown in FIG. 9 controls, for example, the rotation state of a three-phase motor M. The control device 16 is connected to a power supply line PL1 to which a positive reference voltage is supplied and to a ground potential via a resistor R. Between the connected power line PL2 and 2
Stage transistors T1, T2, T3; T4, T5, T6
Is connected. The inverter circuit 17 includes the transistors T1 to T6 and diodes D1 to D6 connected in parallel to the transistors T1 to T6, respectively, and having the power supply line PL1 side as a cathode. Transistors T1, T4; T2, T5; T
3, the coils L1 and L2 of the motor 2 from each connection point of T6.
A drive voltage is supplied to each of L3.

[0007]

In such a prior art, the voltage Vm with respect to the ground potential at the neutral point 19 of the motor 2 has a rectangular waveform as shown in FIGS. 10 (1) and 11 (1). Changes with a relatively large amplitude,
The current Im flowing through the resistor R is also shown in FIGS.
As shown in (2), it is known that the amplitude changes in a rectangular wave shape with a relatively large amplitude.

The changes in the voltage Vm and the current Im are as follows.
In addition to increasing noise generated from the motor 1, a voltage is generated between the rotating shaft 10 and the bracket 11 via a floating capacitance of an electric insulator such as a frame 4 inside the motor 1, and a metal inner ring and an outer ring In addition, a problem arises in that electric erosion is generated in the bearing 8 including the rolling elements and the like, thereby causing rotation failure of the motor 1 and the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a motor capable of reducing the noise of the motor, preventing a rotation defect, and significantly improving the operation quality. To provide.

[0010]

In the motor according to the present invention, a capacity is arranged in parallel between a neutral point of the winding of the star-connected motor and a predetermined reference potential.

According to a second aspect of the present invention, a neutral point of a winding of a star-connected motor and a current outflow side of an inverter circuit which supplies a drive voltage to the motor and includes a plurality of transistors are provided. And a current output terminal of the transistor.

[0012]

In the motor according to the first aspect of the present invention, the capacity is arranged in parallel between the neutral point of the winding of the star-connected motor and a predetermined reference potential. This capacity can stabilize and smooth this voltage even when a voltage having a relatively large rectangular wave-like amplitude is generated at the neutral point of the motor.

Thus, since the driving voltage flowing through the motor has a rectangular waveform or the like, generation of a high-frequency component having a relatively large amplitude included in the driving voltage can be prevented, and noise generated from the motor can be reduced. Further, by preventing generation of a high-frequency component having a relatively large amplitude in the drive voltage, even if a floating capacitance exists due to an electric insulator inside the motor when the motor is a molded motor, the electric insulator can be used. Is prevented from being generated between the metal parts sandwiching it, and the occurrence of electrolytic corrosion on the metal parts is prevented. As a result, poor rotation assumed when the metal component or the like is a bearing is prevented, and in these respects, the operation quality can be significantly improved.

In the motor according to the second aspect of the present invention, the neutral point of the winding of the star-connected motor and the current outflow side of the inverter circuit which supplies a drive voltage to the motor and includes a plurality of stages of transistors. And a current output terminal of the transistor. With this capacity, even when a voltage having a relatively large amplitude in the form of a rectangular wave is to be generated at the neutral point of the motor, this voltage can be stabilized and smoothed. Therefore, the same function and effect as those described in relation to the first aspect of the invention can be realized.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(First Embodiment) FIG. 1 is a block diagram schematically showing an electric configuration of a control device 22 of a motor 21 according to a first embodiment of the present invention, and FIG. FIG. 3 is a block diagram showing the configuration, FIG. 3 is a cross-sectional view of a motor 21 having a configuration serving as a basis of the present invention, and FIG. 4 (1) is a waveform diagram of a potential Vm at a neutral point of the motor 21. (2) is a waveform diagram of the current Im in the resistor R of the control device 22, and FIG. 5 (1) is an enlarged view of FIG.
(2) is an enlarged view of FIG. 4 (2).

FIG. 3 has been described in the section of the prior art, so that the description will not be repeated, and the description will be made with reference to the above-mentioned reference numerals when necessary.

Hereinafter, the electrical configuration of the motor 21 and the control device 21 will be described with reference to FIGS.

The control device 22 is, for example, a three-phase motor 2.
1 to control the rotation state of the motor 21.
For example, a magnetic pole detecting element 23 such as a hall element is provided for each phase, and a change in the magnetic flux density of the rotating magnetic field for each phase of the motor 21 is detected. Thus, the magnetic pole detection element 23 can detect the rotation speed and the rotation direction of the motor 21 and the position in the rotation direction.

The control device 22 includes, for example, an input / output command signal control unit (hereinafter referred to as a control unit) 24 composed of a microcomputer or the like, and further includes a rotation speed at which the position signal P from the magnetic pole detection element 23 is input. The measurement unit 25 is provided.
The rotation speed signal from the rotation speed measurement unit 25 is input to the control unit 24.

A speed command signal corresponding to the reference rotation speed is separately input to the control unit 24. Based on the rotation speed signal and the speed command signal, a control signal having a characteristic of eliminating a deviation between these signals is provided. Is input to the logic circuit 27, where a control signal for turning on / off each transistor of the inverter circuit 28 is created and output to the inverter circuit 28. A DC power supply is connected to the inverter circuit 28, and a voltage / current from the DC power supply is modulated by the inverter circuit 28 and supplied to the motor 21. Thus, the motor 21 is controlled to rotate at the reference speed based on the speed command signal.

Here, the control device 22 of the motor 21 of the present embodiment controls the rotation state of the three-phase motor 21 as an example, and includes a power supply line PL1 to which a positive reference voltage is supplied, A two-stage transistor T1, between a power supply line PL2 connected to the ground potential through R
Inverter circuit 2 including T2, T3; T4, T5, T6
8 are connected. The inverter circuit 28 includes the transistors T1 to T6 and diodes D1 to D6 connected in parallel to the transistors T1 to T6, respectively, and having the power supply line PL1 side as a cathode. A drive voltage is supplied to each of the coils L1, L2, L3 of the motor 21 from each connection point of the transistors T1, T4; T2, T5; T3, T6. Further, a capacitor 30, which is a capacitor, is connected between a neutral point 29, which is a connection point of the coils L1, L2, L3, and a ground potential. The capacitor 30 is connected in parallel with the coils L1, L2, L3.

According to the motor 21 and the control device 22 having such a configuration, even when the capacitor 30 generates a voltage having a relatively large amplitude in the form of a rectangular wave at the neutral point 29 of the motor 21, the voltage is reduced. It can be stabilized and smoothed. Therefore, as shown in FIGS. 4 (1) and 5 (1), the voltage Vm with respect to the ground potential of the neutral point 29 of the motor 21 is different from that of FIGS.
Are stabilized and smoothed as compared with the waveform shown in FIG.

As a result, since the drive voltage flowing through the motor 21 has a rectangular waveform or the like, the generation of a high-frequency component having a relatively large amplitude included in the drive voltage can be prevented, and the noise generated from the motor 21 can be reduced. . In addition, since the generation of the high-frequency component having a relatively large amplitude in the driving voltage is prevented, when the motor 21 is a molded motor, there is a floating capacitance due to an electric insulator such as the frame 4 inside the motor 21. Also, a voltage is prevented from being generated between the rotating shaft 10, which is a metal component sandwiching the electric insulator, and a metal component such as the bracket 11, and electrolytic corrosion occurs in the bearing 8, which is also a metal component. Is prevented. As a result, poor rotation that is assumed when the electrolytic corrosion occurs in the bearing 8 is prevented, and in these respects, the operation quality can be significantly improved.

(Second Embodiment) FIG. 6 is a block diagram showing an electrical configuration of a second embodiment of the present invention.
Is a voltage V corresponding to FIGS. 4 and 5 in this embodiment.
FIG. 6 is a waveform diagram of m and a current Im. This embodiment is similar to the first embodiment, and corresponding parts are denoted by the same reference numerals. This embodiment is characterized in that the coils L1, L
2. A capacitor 30 is connected in parallel between the neutral point 29 of L3 and the power supply line PL1.

In this embodiment, the neutral point 2 of the motor 21
Even when a voltage having a relatively large amplitude in the form of a rectangular wave is to be generated in the capacitor 9, the capacitor 30 can stabilize and smooth this voltage. Therefore, also in the present embodiment, it is possible to realize the same operation and effect as those described in regard to the first embodiment.

As another modified example of the present invention, the capacitor is connected in parallel between the neutral point 29 and the emitters, which are the current output terminals of the transistors T4, T5 and T6 on the current outflow side of the inverter circuit 28. May be arranged. Even when a capacitor having a relatively large amplitude in the form of a rectangular wave is to be generated at the neutral point 29 of the motor 21 by the capacitor connected in this way, this voltage can be stabilized and smoothed. Therefore, the same operation and effect as the above-described operation and effect can be realized.

[0028]

As described above, in the motor according to the first aspect of the present invention, the capacity is arranged in parallel between the neutral point of the winding of the star-connected motor and a predetermined reference potential. This capacity can stabilize and smooth this voltage even when a voltage having a relatively large rectangular wave-like amplitude is generated at the neutral point of the motor.

Thus, since the driving voltage flowing through the motor has a rectangular waveform or the like, the generation of a high-frequency component having a relatively large amplitude included in the driving voltage can be prevented, and noise generated from the motor can be reduced. Further, by preventing generation of a high-frequency component having a relatively large amplitude in the drive voltage, even if a floating capacitance exists due to an electric insulator inside the motor when the motor is a molded motor, the electric insulator can be used. Is prevented from being generated between the metal parts sandwiching it, and the occurrence of electrolytic corrosion on the metal parts is prevented. As a result, poor rotation assumed when the metal component or the like is a bearing is prevented, and in these respects, the operation quality can be significantly improved.

In the motor according to the second aspect of the present invention, the neutral point of the winding of the star-connected motor and the current outflow side of the inverter circuit which supplies a drive voltage to the motor and includes a plurality of stages of transistors. And a current output terminal of the transistor. With this capacity, even when a voltage having a relatively large amplitude in the form of a rectangular wave is to be generated at the neutral point of the motor, this voltage can be stabilized and smoothed. Therefore, the same function and effect as those described in relation to the first aspect of the invention can be realized.

[Brief description of the drawings]

FIG. 1 shows a control device 22 for a motor 21 according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating an outline of an electrical configuration of FIG.

FIG. 2 is a block diagram showing an electrical configuration of a control device 22.

FIG. 3 is a simplified cross-sectional view of a molded motor (hereinafter, motor) 1 having a configuration serving as a basis of the present invention.

FIG. 4 is a waveform diagram of a potential Vm at a neutral point of a motor 21 and a current Im at a resistor R.

FIG. 5 is an enlarged view of the waveform of FIG.

FIG. 6 is a block diagram showing an electrical configuration of a second embodiment of the present invention.

FIG. 7 shows a neutral potential Vm and a resistance R in the present embodiment.
FIG. 6 is a waveform diagram of a current Im at the point.

FIG. 8 is an enlarged view of the waveform of FIG. 7;

FIG. 9 is a block diagram showing a schematic electrical configuration of a motor 1 according to the related art.

FIG. 10 shows the potential Vm and the resistance R of the neutral point 17 of the motor 1.
FIG. 6 is a waveform diagram of a current Im at the point.

FIG. 11 is an enlarged view of FIG. 10;

[Explanation of symbols]

 4 Frame 8 Bearing 10 Rotating shaft 11 Bracket 21 Motor 22 Control device 24 Control unit 28 Inverter circuit 29 Neutral point 30 Capacitor D1 to D6 Diode Im Current in resistor R L1, L2, L3 Coil PL1, PL2 Power line R Resistance T1, T2, T3; T4, T5, T6 Transistor Vm Potential at the neutral point of the motor 21

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H560 BB04 DA02 DB02 EB01 EB07 EC02 GG04 JJ12 RR10 SS01 TT15 UA02 XA04 5H576 BB04 BB06 CC01 DD02 DD05 GG01 HA02 HB01 JJ03 LL05 LL41

Claims (2)

[Claims] 1. A motor in which a capacity is arranged in parallel between a neutral point of a winding of a star-connected motor and a predetermined reference potential. 2. A winding neutral point of a star-connected motor;
A motor for supplying a drive voltage to a motor, wherein a capacitor is arranged in parallel with a current output terminal of the transistor on a current outflow side of an inverter circuit including a plurality of stages of transistors.