JPH0984325A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stepping motor which makes it possible to obtain a large output and to conduct a normal operation at a high temperature with a small size. SOLUTION: In the stepping motor comprising a rotor having multipolar permanent magnet, and a multipolar stator 1 in which coils 2A to 2A are wound on the stators 1A to 1F of the poles, the stator is magnetically coupled in the circumferential direction of the rotor 3 in the state that the stators 1A to 1F of the poles of the stator 1 are previously wound with the coils 2A to 2F, the coils 2A to 2F are three-phase wound having current input and output points, and bipolarly driven.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and more particularly to a stepping motor which is small in size and can operate at high speed and generate a large output.

[0002]

2. Description of the Related Art Conventionally, stepping motors and DC servo motors have been used as drive motors in a wide range of fields such as office automation equipment, factory automation equipment, automobiles, medical equipment, housing equipment, gaming machines, and industrial machines, and have high precision. Rotation, stop,
Enables positioning control.

[0003]

In recent years, conveyors, elevators, indexing and rotating devices, particularly winding machines, looms, blinds, shutters, curtains, etc., as well as polishing machines, valve opening / closing, vacuum generating devices, discriminating machines, etc. The driving device of (1) requires a large torque (large output). As a drive motor in a field requiring such a large output control, a DC motor or a DC is usually used.
Brushless motors and AC brushless motors are used. However, in these motors, a sensor for obtaining position information, that is, a positioning sensor (Hall element, encoder, or the like) is indispensable, and there is a problem in that the size of the entire apparatus is large and expensive. Further, since such a sensor usually has a semiconductor element, it cannot operate at a high temperature, and is subject to restrictions on operating environment conditions. Furthermore, when controlling the loads of many curtains and blinds in a building, the loads are not the same, so
There is also a problem in that synchronous operation control is difficult because the control and drive times are deviated due to the respective loads.

For example, an AC used for continuous operation
The servo motor drive system has a complicated circuit configuration, requires a rotation sensor such as an encoder, and is large and expensive. On the other hand, a sensor such as an encoder is weak against heat and has an ambient temperature of 80%.
It cannot be used in high temperature environment above ℃. Further, a deviation counter may be provided to correspond to the required load torque, but since synchronization may advance or delay with respect to the input pulse train signal by the number set by the deviation counter,
Problems arise when operating multiple motors in parallel synchronously with one signal.

Since the stepping motor performs the open loop control operation, the above-mentioned problem does not occur, but, for example, there is no stepping motor capable of obtaining a continuous rated output of several hundred watts or several thousands watts. This is because it is necessary to apply a large current to the winding in order to obtain a large output, but then, the winding heats up, and the more it tries to obtain a large output, the winding heats up. This is because the operation becomes impossible and the winding may be burned out.

[0006] For example, as a medium-sized or large-sized stepping motor, a two-phase, three-phase, four-phase, or five-phase hybrid type is generally used, which is suitable for fine step feed using a ball screw nut and high-accuracy positioning. Therefore, the development of stepping motors that can achieve fine step angles and high resolution through the use of multiple phases and multiple poles is progressing. Among existing stepping motors, it is a five-phase hybrid type, 100 poles, half step angle 0.36 degrees, one rotation 1000 divisions with the most advanced resolution. In such a high-resolution stepping motor, an operating speed is ensured, and the maximum number of revolutions per minute is 3000 (RP
M), so that the driver is AC10
A power source in which 0 [V] is converted to DC 140 [V] is used. In the 5-phase stepping motor of this example, 30
00 (RPM) is a pulse rate of 50,000 (P
PS) and 2500H for the stator coil of the motor
The 5-phase AC power supply of z flows, and the high-frequency current causes the motor to generate heat. Specifically, 3000 (R
In (PM), the temperature of the coil rises by 100 ° C. within a few minutes and continuous operation becomes impossible. Therefore, the stepping motor is currently used only for the intermittent operation purpose in which it operates only for a short time.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a small stepping motor which can obtain a large output and can be normally operated at a high temperature.

[0008]

In order to solve the above-mentioned problems, a stepping motor according to the present invention has a rotor having multi-pole permanent magnets and a multi-pole stator having coils wound around the respective poles. A stepping motor,
The multi-pole stator is magnetically coupled in the circumferential direction of the rotor in a state in which the stator portions of the respective poles of the multi-pole stator are wound in advance, and the coil has a three-phase winding having current inflow / outflow points. And is configured to be driven in a bipolar manner.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of a motor according to an embodiment of the present invention.

In this embodiment, a 3-phase 6-pole stator and 4
It is a motor having a pole rotor, and the stator is composed of six stators 1A to 1F for each pole, and coils (windings) 2A to 2F are wound around the stator of each pole in advance. There is.

In the conventional stepping motor, since the stators 1A to 1F are integrated, in order to wind the coil around each pole stator, the winding machine avoids interference with the coils of adjacent pole stators. There is no choice but to carry out the winding work, and a certain distance or more is required between the winding coils of the adjacent pole stators. Therefore, there is a restriction on the number of coil windings that can be wound, and in order to obtain a large output, a large current must be passed, which causes the above-described problem of coil heat generation.

On the other hand, in this embodiment, since each pole stator is molded in a separated state, it is not necessary to consider interference with the adjacent stator and coil when winding the coil. . Therefore, the maximum number of coil windings can be obtained with high density. That is, as shown in FIG. 1, the interval between adjacent coils can be narrowed to the extent that there is no interference between the coils of adjacent stators in a state where the respective pole stators 1A to 1F are coupled, so that the number of coil windings is the same as that in the conventional case. Compared with this, a large amount can be obtained, and a large output can be obtained with a relatively small current.

In this way, the stators 1A to 1F around which the coils 2A to 2F are respectively wound are fixed and magnetically coupled to each other by a laser fixing technique or the like to form the stator 1. Inside the stator 1, there are rotor magnets 3 for each pole.
A rotor 3 having A to 3D is installed. In the figure, 4
Is the back iron of the rotor.

Although the above-mentioned example is the inner rotor type, it may be an outer rotor type having a reverse structure, and the windings may be independent of three phases, or may be of delta connection or star connection. .

FIG. 2 shows a bipolar drive exciting circuit for driving the stepping motor shown in FIG. NPN transistors Q1 and Q2, Q3 and Q connected in series between the motor drive voltage positive pole VM and the negative pole GND
A series circuit of 4, Q5 and Q6 is connected in parallel as shown. Transistors Q1, Q3 and Q5 are current inflow side switching elements, and transistors Q2, Q4 and Q6 are current outflow side switching elements. The emitter sides of the transistors Q1, Q3 and Q5 are connected to the three-phase coil connection ends U, V and W.

FIG. 3 shows an excitation sequence of 2-3 phase excitation. The ON state of the transistors Q1 to Q6 as switching elements in each excitation step, the coil U,
The relationship between the polarities of V and W is shown. As is clear from FIG. 3, the number of points at the current inflow point and the current outflow point is 2-3 points.

FIG. 4 shows the torque vector directions with reference to the coil ends U, V, W in the excitation step. In the figure, the white circles indicate the current inflow points, the black circles indicate the current outflow points, and the central portion The numbers surrounded by "" indicate the excited state.
The full excitation step thus obtained and the torque vector direction for one revolution are shown in FIG. 5, and the 2-3 point sequence and the 2-3 phase excitation sequence are completed in 12 steps.

When the motor configuration shown in FIG. 1 is used, the above sequence results in a half step angle of 15 degrees, and a three-phase stator and an 8-pole rotor can obtain a half step angle of 7.5 degrees.

FIG. 6 shows a 3-3 phase excitation sequence and a 2-2 point excitation sequence in the same relationship as in FIG. Further, FIG. 7 shows a torque vector circuit diagram obtained in the excitation step of FIG.

Similarly, in FIG. 8, 2-2 phase excitation, 3-3
The point excitation sequence has the same relationship as in FIG. 6, and FIG. 9 shows a torque vector loop diagram obtained in the excitation step of FIG.

As described above, by constructing the motor and the drive circuit and adopting the constant current drive system such as the bipolar common chopper, the stepping motor drive system of a small size, large output, high efficiency, low heat generation and low cost can be obtained. can get.

Next, the operation principle of the above stepping motor will be described with reference to FIGS. FIG. 10 shows the stable stationary position of the rotor in the two-phase excitation state, which corresponds to the state “2” in FIG. Next, when the excitation is switched to the state "4" in FIG. 4 and the three-phase excitation state is set, the rotor stepwise rotates to the position shown in FIG. 11 and stands still. The step angle at this time is a half step angle of 15 degrees. Less than,
As shown in FIGS. 12 and 13, the process proceeds at a half step angle. FIG. 13 corresponds to the state “5” of FIG. continue,
From the three-phase excitation state of the state "5" in FIG. 4 to the state "7" in FIG.
As shown in FIG. 14, the full-step rotation of 30 degrees causes the full-step rotation. Similarly, a full step rotation of 30 degrees is performed in FIGS.

A full step rotation can also be achieved by performing 2-2 phase excitation as shown in FIG.

FIG. 16 is a block diagram showing an embodiment of the stepping motor according to the present invention, which is a three-phase bipolar motor, a stator having 12 poles, and a rotor having 8 poles. The motor size is 40 mm in outer diameter and 70 mm in length. Is. The constant current common chopper method shown in FIG. 2 is used as the excitation circuit, and the excitation sequence is as shown in FIG. 3 and the excitation state is as shown in FIGS. 4 and 5. Also, the stator winding is a concentrated winding delta connection,
The rotor uses a neodymium iron boron hot press MQ-III. In this embodiment, the step angle is a half step angle of 7.5 degrees, the coil resistance is 4 Ω / phase, and the drive voltage is DC.
140 [V], 2-3 phase excitation, common 2A constant current drive, holding torque 3.8 [kg-cm], no-load self-starting frequency 1390 [PPS], self-starting rotation speed 17
37 [RPM], continuous response frequency 7350 [PPS],
A continuous response rotation speed of 9187 [RPM] was obtained.

The "speed-pullout torque characteristic" and the "speed-machine output characteristic" obtained in the above embodiment are shown in FIG. 7000 [RPM], pulse rate 560
A mechanical output of 153 [W] was obtained at 0 [PPS], and the mechanical output with respect to the electric input at this time was 65%.

FIG. 18 shows the "speed-saturation temperature rise characteristic" obtained in the present embodiment. The maximum temperature rise is 50 [deg] in the case part by the jacket method, and the motor coil part is resistance. It was 89 [deg] by the method.

The stepping motor according to the present invention can be combined with a so-called "ball speed reducer" having no backlash to form a system capable of driving a large inertial load with a minute angle.

[0028]

As described above, the stepping motor of the present invention does not use a rotation sensor such as an encoder,
High precision and large output can be obtained. Further, since no encoder is required, a low-cost stepping motor that can be used even under adverse conditions such as high temperature, water, space, and severe environments can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a stepping motor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a bipolar driving excitation circuit for driving the stepping motor shown in FIG.

FIG. 3 is a diagram showing an excitation sequence of 2-3 phase excitation in the embodiment of the present invention, showing a relationship between ON states of transistors Q1 to Q6 as switching elements and polarities of coils U, V, W in each excitation step. Is.

FIG. 4 is a diagram showing coil ends U, V, in the excitation step of FIG.
It is a figure which shows the torque vector direction on the basis of W.

FIG. 5 is a diagram showing a direction of a torque vector for one full rotation in FIG.

FIG. 6 is a diagram showing an embodiment of the present invention in which 3-3 phase excitation and 2-
It is a figure which shows a 2-point excitation sequence.

7 is a torque vector circuit diagram obtained in the excitation step of FIG. 6;

FIG. 8 is a 2-2 phase excitation according to the embodiment of the present invention;
It is a figure which shows a 3-point excitation sequence.

9 is a torque vector circuit diagram obtained in the excitation step of FIG. 8. FIG.

FIG. 10 is a diagram for explaining the operation principle of the stepping motor in the above embodiment.

FIG. 11 is a diagram for explaining the operating principle of the stepping motor in the above embodiment.

FIG. 12 is a diagram for explaining the operation principle of the stepping motor in the above-described embodiment.

FIG. 13 is a diagram for explaining the operation principle of the stepping motor in the above embodiment.

FIG. 14 is a diagram for explaining the operating principle of the stepping motor in the above embodiment.

FIG. 15 is a diagram for explaining the operation principle of the stepping motor in the above embodiment.

FIG. 16 is a configuration diagram showing an embodiment of a stepping motor according to the present invention.

17 is a diagram showing "speed-pullout torque characteristics" and "speed-machine output characteristics" obtained by the stepping motor shown in FIG.

FIG. 18 is a diagram showing “speed-saturation temperature rise characteristics” obtained by the stepping motor shown in FIG. 16.

[Explanation of symbols]

 1 Stator 1A to 1F Each pole Stator 2A to 2F Coil 3 Rotor 3A to 3F Rotor magnet 4 Rotor back iron

Claims (1)

[Claims] 1. A stepping motor having a rotor having multi-pole permanent magnets and a multi-pole stator having coils wound around respective poles, wherein the multi-pole stator is each pole of the multi-pole stator. Of the stator part is magnetically coupled in the circumferential direction of the rotor in a state where the coil is wound in advance,
The stepping motor is characterized in that the coil is a three-phase winding having current inflow / outflow points and is driven in a bipolar manner.