JPS6227621B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection device for a rotational phase signal in a three-phase non-commutator motor.

When controlling the mechanical absolute phase of a non-commutated motor with respect to the phase of an external signal, for example, a two-head helical scan type that uses an azimuth recording method is used.
When the rotating magnetic head of a VTR is directly driven by a non-commutated motor to control the mechanical absolute rotational phase of the head, a rotational phase signal (hereinafter referred to as PG
signals).

Conventionally, in order to obtain such a PG signal, a single magnet piece was attached to the rotating part of the motor, and the magnetic flux of the magnet piece was detected by a magnetic sensing element.
Many signal methods are used. However, in this type of system, the dynamic balance of the rotating body is disrupted by attaching a magnet piece to the rotating part of the motor, and the number of parts and lead wires for the magnetic sensing element increase, resulting in increased man-hours and material costs for assembling the motor. It has the disadvantage of causing an increase in In addition, as a method to solve such problems, a permanent magnet that constitutes the rotor of a non-commutated motor is magnetized with two poles, and the magnetic flux of this permanent magnet is detected and used as a position signal for commutation of the motor. A method has been proposed in which the PG signal is used as well as the PG signal. However, electric motors with a small number of magnetic poles generally have a low frequency of the fluctuation component of the generated torque and a large rotational fluctuation rate, making it difficult to employ them when high-performance rotation is required.

The present invention solves the problems of the conventional example as described above, and even when the number of magnetic poles of the rotor of a three-phase commutator is four or more, the rotational phase of the motor can be adjusted without using any extra members. It is possible to obtain a PG signal.

Hereinafter, the present invention will be explained based on illustrated embodiments. FIG. 1 shows 3
FIG. 2 is a configuration diagram of main parts of a phaseless commutator motor. In FIG. 1, reference numeral 1 denotes a position detection rotating body made of a ferromagnetic material, which rotates integrally with the rotating shaft 9.
A position detection track 2 and a second position detection track 3 are formed concentrically. The first position detection track 2 and the second position detection track 3 are
The south and north poles are encoded and magnetized as two physical states A and B, respectively. Reference numeral 4 denotes a first position detecting element made of a magnetically sensitive element using the Hall effect, which is disposed on a suitable fixed part so as to detect the encoded magnetic pole of the first position detecting track 2. ing. Reference numeral 5 denotes a second position detecting element made of a magnetically sensitive element utilizing the Hall effect for detecting the coded magnetic pole of the second position detecting track 3, and this is also disposed on a suitable fixed part. ing. A rotor 7 is made of a cylindrical permanent magnet whose outer circumferential surface is magnetized with four poles, and rotates together with the rotating shaft 9. 8 is the three-phase excitation winding Ma,
A stator consisting of Mb and Mc, which may also include a stator core. The position detection rotating body 1, the first position detection element 4, and the second position detection element 5 constitute a position detection means 10.

FIG. 2 is a detailed diagram of the position detection means in FIG. 1. In FIG. 2, the same components as those explained in FIG. 1 are given the same reference numerals. In FIG. 2, the first position detection track 2
is magnetized with four poles corresponding to the number of magnetic poles of the permanent magnet 7, and is magnetized so that the magnetization angle of the S pole and the N pole during one electrical cycle is 1:2. A first position detecting element 4 and a second position detecting element 5 having input terminals A and B and output terminals D and C are arranged with an angular difference of θ ₀ as shown. Here, the illustrated position A is set to the first position detection track 2.
The phase of A with respect to the first position detection element 4 in the counterclockwise direction is θ _n . The second position detection track 3 is magnetized with 6 poles, and θ
The S pole has an angular width of ₁ , θ ₂ , θ ₅ , and the S pole has an angular width of θ ₂ , θ 5 .
The N pole is magnetized with an angular width of θ ₄ and θ ₅ , and θ
₁ +θ ₂ +θ ₃ +θ ₄ = π, θ ₅ +θ ₆ = π,
π/3<θ ₁ <2π/3, 0<θ ₂ +θ ₃ <π/
3(θ ₂ , θ ₃ >0), π/3<θ ₁ +θ ₂ +θ
₃ <2π/3, π/3<θ ₅ <2π/3.

Further, in the second position detection track, the detection state of the magnetic pole of the second position detection element 5 changes from N pole to S pole at positions where θ _n is approximately π/3, 4π/3, and θ _{1 +} θ 2 +π/3. , and θ _n is θ ₁ +π/3,
It is magnetized so as to change from the S pole to the N pole at the positions θ ₁ +θ ₂ +θ ₃ +π/3 and θ ₅ +4π/3.

FIG. 3 is a main circuit block diagram of this embodiment, and FIG. 4 is a waveform diagram of the main parts in FIG.

In FIG. 3, E _H is a DC power source with one end grounded. The input terminal B of the first position detecting element 4 is grounded, the other input terminal A is connected to one input terminal B of the second position detecting element 5, and the other input terminal I of the second position detecting element 5 is grounded. is connected to one end of the ungrounded side of the DC power source _EH . 11 is a logic processing means, which includes differential amplifiers 12 and 13, waveform shapers 14 and 15, and an inverter circuit 17;
NOR gate circuits 16, 18, 19, 20,
It is composed of an AND circuit 21. Inverter circuit 17, NOR gate circuit 18, 19, 20,
The AND gate circuit 21 constitutes a PG signal detection means. Two outputs with a phase difference of 180° are inputted to the differential amplifier 12 from the first position detection element 4, and the outputs are waveform-shaped by a waveformer 14 to form a waveform as shown in FIG. 4a. During the period when position detection element 1 detects the N pole, it becomes low level.
Furthermore, during the period when the S pole is being detected, a signal a that is at a high level is output.

Further, the two outputs with a phase difference of 180° from the second position detection element 5 are input to the differential amplifier 13, and the output is input to the waveform shaper 15 and the fourth output is input to the differential amplifier 13.
As shown in Figure b, the second position detection element is at low level during the period when it detects the N pole, and
During the period for detecting a pole, a signal b that is at a high level is output.

In other words, the output a of the waveform shaper 14 is 0≦θ _n ≦2π/3, π≦θ _n during one rotation of the position detection rotating body 1
Outputs low level when ≦5π/3, and outputs low level when 2π/3≦θ
A high level is output when _n ≦π, 5π/3≦θ _n ≦2π. Further, the waveform shaper 15 is connected to the position detection rotating body 1.
0≦θ _n ≦π/3, θ _a ≦θ _n ≦θ _b
(However, θ _b −θ _a = θ ₂ , θ _a = θ ₁ + π/
3), θ _c ≦θ _n ≦4π/3 (where θ _c = θ ₁ +
During the period θ ₂ + θ ₃ + π/3), a low level is output, and π/3≦θ _n ≦θ _a , θ _b ≦θ _n ≦θ _c , 4π/
3≦θ _n ≦θ _d (where θ _d = θ ₁ + θ ₂ + θ ₃
+θ ₄ +θ ₅ +π/3), a high level is output. Signal a and signal b are connected to NOR gate circuit 16
The signal c shown in FIG. 4 is obtained. Here,
The signals a and c output a ground voltage at a low level and a voltage level of 5 (V) at a high level. In addition, the signal a is inverted through the inverter circuit 17 and the NOR gate circuit 1
8, 20, and also NOR gate circuit 1
A signal b is also input to 8, and its output is input to a NOR gate circuit 19. Then, the output of the NOR gate circuit 19 is inputted as an input signal of the NOR gate circuit 20, and the output of the NOR gate circuit 20 is inputted as an input signal of the NOR gate circuit 20.
By inputting it as an input signal to the NOR gate circuit 19, a signal d shown in FIG. 4d is obtained. Signals d and b are input to the AND gate circuit, and as shown in FIG _.
A PG signal e is obtained which outputs a high level only during the period of θ _n ≦ θ _c .

As described above, two-phase position signals a and c, which correspond to the rotational phase of the rotor 7 and have an electrical phase difference of 120 degrees, are generated, and one pulse is generated for each rotation of the rotor. This is to obtain a signal (PG signal) e. Furthermore, in FIG. 3, Q _a , Q _b , Q _c are NPN transistors whose emitters are commonly connected and grounded via a current source I _E , and each collector has an excitation winding M _a , M _b , M _c are connected at one end. Signal a is input to the base of transistor Q _a , signal c is input to the base of transistor Q _b , and a potential of approximately 2.5 V is applied to the base of transistor Q _c by DC power supply V _P. . E _M is a DC power supply whose one end is grounded, and the other terminals of the excitation windings M _a , M _b , M _c that are not connected to the collectors of the transistors Q _a , Q _b , Q _c are connected to each other. has been done. With such a configuration, during one rotation of the position detecting body 1, two
During the period of π/3≦θ _n ≦π, 5π/3≦θ _n ≦2π, the excitation winding M _a is set to 0≦θ _n ≦π/3, π≦θ _n ≦4.
During the period of π/3, the excitation winding M _b is
The current from the current source I _a can flow through M _c during the period of θ _n ≦2π/3, 4π/3≦θ _n ≦5π/3.

Note that the same effect as above can be obtained by inputting a NOR gate signal of the inverted signal of signal b and signal a instead of inputting a DC potential through V _P to the base of transistor Q _c . Needless to say.

As is clear from the above description, the present invention has two
In a three-phase commutatorless motor driven by signals detected by three position detection elements, it is possible to obtain a PG signal without using other mechanical elements.
This makes it possible to reduce the cost of electric motors.

[Brief explanation of the drawing]

Fig. 1 is a main part configuration diagram of an embodiment of the present invention, Fig. 2
The figure is a detailed view of the position detection means section in the same embodiment.
FIG. 3 is a circuit block diagram of the logic processing means section in the same embodiment, and FIG. 4 is a signal waveform diagram of the main parts in FIG. 3. DESCRIPTION OF SYMBOLS 1... Position detection rotating body, 2... First position detection track, 3... Second position detection track, 4...
...First position detection element, 5...Second position detection element, M _a , M _b , M _c ... Three-phase excitation winding, 8 ... Stator, 7 ... Rotor, 9 ... Rotation Axis, 10...Position detecting means, 11...Logic processing means, 22...Carrier plate.

Claims (1)

[Claims] 1 A rotor including a permanent magnet with magnetic poles of 2n (where n is a natural number of 2 or more) poles, a stator including a 3-phase excitation winding, and A and B with different physical characteristics. a ring-shaped first position detection track that rotates integrally with the rotor, in which two states corresponding to the number of poles of the permanent magnet are sequentially encoded in an angular ratio of approximately 1:2; a first position detecting element disposed at the fixed part for detecting two physical states of the first position detecting track; and a second position detecting element disposed at the fixed part for detecting two physical states of the first position detecting track.
The state changes 3 times in one section of the n sections in which the first position detection element detects the physical state A every rotation of the rotor, and once in the other n-1 sections. Further, in a section in which the first position detecting element detects physical state B, a second position detecting element is encoded so as to change by one degree approximately at the center of the section, and rotates integrally with the rotor. A three-phase non-commutator motor is configured with a track, and the three-phase excitation winding is sequentially excited every 120/n degree rotation of the rotor by the first and second position detection outputs, When the first position detecting element detects the physical state A within the detection interval, the second position detecting element detects a pulse-like pulse in the interval from the second change to the third change in the physical state detected by the second position detecting element.
1. A rotational phase signal detection device for a commutatorless motor, comprising a PG signal detection means for outputting a PG signal.