JPH0469037A - Motor incorporating position detector - Google Patents

Abstract

PURPOSE:To improve controllability by setting the skew value of stator pole or rotor pole at 0.2-0.6 pitch. CONSTITUTION:A stator pole 34 or a rotor pole 44 comprises first group of torque pole energized by first phase, second group of torque pole energized by second phase, and a sensor pole outputting a rotor position detection signal. Skew value of the stator pole 34 or the rotor pole 44 is set at 0.2-0.6 pitch. According to the constitution, nonexciting torque can be reduced without sacrifice of position detecting capability such as rotor position detecting accuracy or resolution resulting in overall improvement of controllability.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a motor with a built-in position detector, and more particularly to improving the position control ability of a motor with a built-in position detector, such as a brushless DC motor.

(b) Prior Art Brushless DC motors are widely used in devices that require precision, response characteristics, and reliability, such as robots, X-Y tables, integrated circuit manufacturing equipment, and magnetic disk drives.

In particular, the brushless DC motor disclosed in Japanese Patent Application Laid-Open No. 62-244265 is one of the most improved brushless DC motors today in terms of accuracy, response characteristics, and reliability.

First, the brushless DC motor disclosed in Japanese Unexamined Patent Publication No. 61-244265 will be explained with reference to FIGS. 3 and 4.

Figure 3 (A) shows the cross-sectional shape of the stator and its coil structure. It is shown with rectangular stator poles (34) arranged in a row and a coil (38) wound around each ball (34).

Stator pole (34) of the illustrated motor operating in two phases
are the torque balls of the first groove indicated by the circled numbers 1.2.4.5.7.8.9.10.11 and 12, the same <13.14.15.16.17.18.19. 21.
They are further classified into three groups: a second group of torque balls designated 22 and 24, and further sensor balls designated 3.6.20 and 23.

The first group of torque balls are wound with polarity as shown, wired together and energized by the first phase power supplied to terminals (60) and (62). Similarly, the second group of torque balls are energized by second phase power supplied to terminals (64) and (66), respectively, to generate torque on the rotor. The feature of this motor is that a coil is connected to each adjacent pair of torque balls, and when the coil is energized, the coils are wound in opposite directions so that magnetic flux flows between the pair of torque balls. . Further, the sensor poles arranged adjacent to the torque balls other than the pair of adjacently arranged and magnetically coupled torque balls are wound with polarity as shown in the figure, connected in a bridge manner, and connected to their terminals (52) and (54). A high frequency wave of approximately 100K I-T□ is applied to the terminals (48) and (50) to generate signals that have a phase difference of π/2 and that change in accordance with the rotor position. The sum of the numbers of torque balls and sensor balls divided by the number of phases becomes an even number.

FIG. 3(B) shows the cross-sectional shape of the rotor. Lota (40)
is a cylindrical core (42), 18 rotor balls (44)
and shirt) (46). The rotor balls (44) are formed of high-magnetic permanent magnets such as samarium/cobalt alloy, and are arranged on the outer peripheral surface of the cylindrical core (42) by appropriate means so that their polarities are alternately different.
It is fixed. The ratio of the number of stator balls mentioned above to the number of rotor balls is 4:3 or 4'5.

FIG. 4 is a block diagram of a system for digital PID control of a brushless DC motor having the above-described structure.

The first and second groups of torque balls of the motor M are supplied with first phase and second phase power from amplifiers HA and H8, respectively, and are connected to terminals (5) at the tip of the sensor balls.
2) (54) receives 100KHz from the oscillation circuit (122)
A high frequency signal of about

Line (124) from bridge connected sensor ball
(126), which have a phase difference of π/2 and change as the rotor rotates, are converted into vector signals by the synchronous detection circuit (120), and then
It is converted into a rotor position signal by the rotor position detection circuit (108). This rotor position signal may be an external reference signal input manually to the terminal (132) or a microprocessor (
100) internally outputs the reference signal and the manual addition circuit (11
0), and the PID control circuit (112>(114)
(116), and well-known digital PID control is performed.

By the way, it is known that in a brushless DC motor in which the rotor ball and stator ball are not skewed, unexcited torque (day tint torque) is generated due to the permanent magnet of the rotor ball magnetically attracting the stator ball. ing. That is, referring to FIG. 5, which schematically shows the structure of a motor designed to have a skew value of 20,
When the excitation of the stator ball (34) is stopped when the rotor ball (44) and the stator ball (34) are in the positional relationship shown in the figure, the rotor ball (44) formed by a high-magnetic permanent magnet is moved to the stator ball (44). The rotor ball (44) magnetically attracts the stator ball (34).
) Rotate the rotor (40) so that it is located directly below the rotor (40).

In the above-mentioned digital PID control system, this non-excitation torque causes the rotor (40) to rotate after the position control for the target value is completed, and therefore becomes a residual deviation of the control system, causing unstable operation of the control system. Therefore, in brushless DC motors used for position control, as shown in Figure 6, it is common practice to provide a 1.0 pitch pitch knee to the rotor ball (44) to remove non-excitation torque. It is.

(c) Problems that the invention attempts to resolve
When we prototyped the brushless DC motor and its control system disclosed in No. 4265 and conducted repeated experiments, we found that the overall control performance such as stability and coordination of the motor and control system was lower than expected, and we found that the reason behind this was lower than expected. It turned out that the problem was not due to the control system but to circumstances specific to that type of motor.

Therefore, the problem to be solved by the present invention is based on elucidation of the above-mentioned causes, and is particularly aimed at motors with built-in position detectors that use part of the stator ball as a sensor ball for detecting the rotor position. The purpose is to improve controllability.

(d) Means for Solving the Problems The present invention has been made in view of the above problems, and provides a motor with a built-in position detector that uses a part of the stator ball as a sensor ball for detecting the rotor position. The skew value of the ball or rotor ball is 0.2~
By setting the pitch to 0.6, the controllability is greatly improved.

(E) Function In a motor with a built-in position detector that uses a part of the stator ball as a sensor ball for position detection, the pitch of 0.2 to 0.6 pitch is the unexcited torque and rotor position detection accuracy. A singular value that satisfies both of
A motor with a built-in position detector that has good controllability within this range of skew values is realized.

(f) Example Prior to describing embodiments, the present invention will be explained in detail.

Performance evaluation of motors driven by PID control systems is typically extremely difficult. However, by prototyping and experimenting with a large number of samples, the inventor of the present invention was able to focus on the position detectability of the sensor ball and the non-excitation torque as parameters governing the controllability of the motor with a built-in position detector.

In other words, even in a motor with a built-in position detector that uses part of the stator ball as a sensor ball for position detection, the unexcited torque can be reduced by providing a large knee to the rotor ball or stator ball. However, it is not unreasonable to think that the controllability that is controlled by it will improve.

On the other hand, for motors that use part of the stator ball as a sensor ball for position detection, if a large skew is applied to the rotor ball or stator ball,
It is also readily understood that the inductance change and magnetic flux change corresponding to the rotor position change detected by the sensor ball will become smaller or become ambiguous.

Fig. 2 conceptually shows such a relationship, where the broken line indicates the control ability that is governed by the sensor ball's position detection accuracy, and the dashed-dotted line indicates the control ability that is governed by the non-excitation torque.
Furthermore, the solid line shows the overall control ability that takes both factors into consideration.

Therefore, the inventor of the present invention prototyped a number of samples with different skew values of the stator ball and rotor ball, and
When we judged the performance of each in terms of stability, quick response, and residual deviation, we found that the rotor skinny value = 0.2 ~
0.5 pitch, and status knee value 20.3~0
．． A motor with good overall controllability in 6 pitches was realized.

Next, one embodiment of the present invention will be described with reference to FIG.

The motor with a built-in position detector as an example is generally similar to the brushless DC motor disclosed in Japanese Patent Laid-Open No. 62-244265, which was explained in the section of the conventional example, so the connection relationship and control of the stator coils will be different. A description of the system will be omitted.

FIG. 1 is a side view of an embodiment in which the stator is given a skew of 0.5 pitch, and some stator balls are added in a perspective view.

The rotor (40) includes a cylindrical rotor core (42), rotor balls (44) formed of rectangular permanent magnets and arranged and fixed to the outer peripheral surface of the rotor core (42) so that their polarities are alternately different; Consisting of a shaft (46),
Further, the stator is formed by laminating thin steel plates each having an annular portion and a plurality of stator balls as shown in FIG. 3(A). Accordingly, the stator ball (34) shown in FIG. 1 is a cross-sectional view of a laminated stator ball.

In the embodiment of the stator skew shown in the figure, rectangular permanent magnets can be used for the rotor balls, so the rotor is relatively easy to manufacture, and the stator is also made of thin steel plates punched into the same shape with a skew value of 0. Since the laminated layers are formed in a staggered manner to correspond to a pitch of 3 to 0.6, the motor is particularly advantageous in that it is easy to manufacture the motor.

Although not shown in the drawings, a rotor skew motor is realized by fixing permanent magnets deformed such that the rotor skew value is 0.2 to 0.5 pitch as a rotor ball (44) to the rotor core (42). Ru.

The present invention has been described above using as an example a motor with a built-in position detector that uses a part of the stator ball as a sensor ball for position detection. Widely applicable.

(G) Effects of the Invention As described above, according to the present invention, the skew value of the stator ball or rotor ball is set to 0°2 to 0.6 pitch, which reduces position detection performance such as rotor position detection accuracy and resolution. It is possible to reduce the non-excited torque without causing any damage, thereby realizing a motor with a built-in position detector that has good overall controllability.

Further, by employing the status cue, manufacturing of the rotor and stator becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a side view of a rotor illustrating an embodiment of the present invention;
Fig. 2 is a control characteristic diagram explaining the present invention in detail, and Fig. 3 (
A) and (B) are sectional views of the stator and rotor of the brushless DC motor, respectively, FIG. 4 is a block diagram of the control circuit of the brushless DC motor, and FIGS. 5 and 6 are diagrams explaining non-excitation torque. , FIG. 5 is a schematic diagram of a motor with no skew, and FIG. 6 is a schematic diagram of a motor with a skew value of 1.
A schematic diagram of a 0 pitch motor. Staff 27 (40)...Rotor, (42)・Rotor core,
(44) Rotor ball, (46)・Shaft, (34)
-Stator ball. Applicant Oriental Motor Co., Ltd.

Claims (6)

[Claims] (1) A stator ball or a rotor ball outputs at least a first group of torque balls energized by the first phase, a second group of torque balls energized by the second phase, and a rotor position detection signal. A motor with a built-in position detector, which consists of a sensor ball with a stator ball or a rotor ball having a skew value of 0.2 to 0.6 pitch. (2) The motor with a built-in position detector according to claim 1, wherein the skew value of the stator ball is 0.3 to 0.6 pitch. (3) The motor with a built-in position detector according to claim 1, wherein the skew value of the rotor ball is 0.2 to 0.5 pitch. (4) The torque ball includes a pair of adjacently arranged and magnetically coupled torque balls, and the sensor ball is arranged adjacent to a torque ball other than the adjacently arranged and magnetically coupled pair of torque balls, and 4. The motor with a built-in position detector according to claim 2, wherein the sum of the number of sensor balls and the number of sensor balls is divided by the number of phases to give an even number. (5) 4 sensor balls, 4 torque balls that are coupled with the sensor balls but not magnetically coupled with adjacent torque balls, and 16 torque balls that are magnetically coupled with the adjacent torque balls. Motor with built-in position detector. (6) The ratio of the number of stator balls and rotor balls is 4:3
5. The motor with a built-in position detector according to claim 4, wherein the ratio is 4:5.