JPH11146680A - Driver for multiphase motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driver for a multiphase motor, which can downsize the motor itself and whose assembly work becomes simple, by lessening the number of parts. SOLUTION: A frequency signal proportionate to the rotational speed of a motor is outputted from an FG pattern 12 being a rotational speed detecting means provided within a motor. A signal processing means 18 produces first, second, and third drive signals which bring the phase difference of 1/3 cycle into existence with one another, on the basis of the above frequency signal. Moreover, a motor drive circuit 17 generates coil currents Iu, Iv, and Iw with each timing of first, second, and third several drive signals Eu, Ev, and Ew, and supplies them to the coils 7u, 7v, and 7w for drive of a three-phase motor. Therefore, there is no necessity to use a Hall element, and a conventional pattern can be also used for it, so the cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving apparatus for a polyphase motor used in a floppy disk drive or the like.
The present invention relates to a polyphase motor drive device capable of reducing costs by reducing the number of parts.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a conventional driving device for a three-phase motor. The three-phase motor 51 is, for example, a three-phase DC
A brushless motor is mounted on a floppy disk device or the like, and is used as a motor for rotating a disk at a constant speed. For the three-phase motor, reference numeral 51u (U phase),
Motor coils (driving coils) of the respective phases indicated by 51v (V phase) and 51w (W phase) are provided, and the generated torque of each of the motor coils 51u, 51v, and 51w is one.
They are arranged so as to have a phase difference of 20 °. Further, three Hall elements 52u, 52v, 52w are provided at positions close to the motor coils 51u, 51v, 51w. A rotor magnet provided inside the three-phase motor 51 is provided with a driving magnetized portion in which N poles and S poles are alternately magnetized, and the Hall elements 52u, 52v,
52w are fixedly provided at positions facing the driving magnetized portion, respectively. When the rotor rotates, the 3
From the two Hall elements 52u, 52v, and 52w, magnetic detection signals whose phases are sequentially different by 120 ° are obtained.

The output voltages (Hall voltages) Eu0, Ev0, Ew0 of the Hall elements 52u, 52v, 52w are input terminals H1 (+), H1 (-), H2 (+), H2 (-),
The signals are input to the motor driver (motor drive circuit) 53 via H3 (+) and H3 (-). On the other hand, output terminals Au0, Av0, Aw0 of the motor driver 53 are connected to motor coils 51u, 51v, 51w of the three-phase motor, and have predetermined coil currents Iu0, Iv0, Iw.
When 0 is supplied, the three-phase motor is driven to rotate.

FIG. 9 shows a timing chart of the three-phase motor drive circuit shown in FIG. 8, wherein (A) shows a Hall voltage detected by a Hall element and (B) shows a coil current. When the three-phase motor is driven to rotate, each of the Hall elements 52u, 52v,
From 52w, the Hall voltage Eu as shown in FIG.
0, Ev0, Ew0 are detected. Each Hall voltage Eu0, E
v0 and Ew0 are detected as signals corresponding to the direction of the magnetic field of the rotor magnet passing in front of each of the Hall elements 52u, 52v and 52w. For example, when the N pole passes before the Hall element 52u, the Hall voltage Eu0 becomes high level (H), and when the S pole passes, it is detected as low level (L). Other Hall voltages Ev0, Ew0
Are also detected as pulse signals by the Hall elements 52v and 52w in the same manner as described above.
The Hall voltage Eu depends on the mounting position of v and 52w.
0, Ev0 and Ew0 have a phase difference of 1/3 cycle (1
/ 3T; 120 °).

In the motor driver 53, coil currents Iu0, Iv0, Iw0 as shown in FIG. 9B are generated based on the respective Hall voltages Eu0, Ev0, Ew0.
The coil currents Iu0, Iv0, Iw0 are pulse currents,
The hall voltages Eu0, Ev0, Ew0 are generated at the rising and falling edge timings.
When the three-phase motor is rotating at a constant speed, the cycle of the Hall voltages Eu0, Ev0, Ew0 is constant, and the pulse widths of the coil currents Iu0, Iv0, Iw0 are also uniform. Then, such coil currents Iu0, Iv0, I
By supplying w0, the three-phase motor can generate a stable torque with little ripple over the entire rotation angle.

[0006]

However, the conventional three-phase motor drive circuit has the following problems. The first problem is that the drive circuit of the three-phase motor requires a Hall element, and thus the overall cost increases in terms of the number of components. Second, if three Hall elements are housed in a three-phase motor, the overall size of the three-phase motor increases, which hinders miniaturization of the three-phase motor itself.

Further, the three Hall elements are arranged in the three-phase motor at predetermined mounting angles, respectively. If an error occurs in the mounting angle, each of the Hall voltages Eu0, Ev0,
An error occurs in the timing of Ew0. Further, the coil currents Iu0, Iv0, Iw0 correspond to the Hall voltages Eu0, Ev0,
Since the rising and falling edges of Ew0 are generated as trigger signals, each coil current Iu0, Iv0, Iw
A timing shift also occurs at 0, so that the three-phase motor cannot rotate with a stable torque. Therefore, since the mounting operation of the Hall element requires high mounting accuracy, a high level of assembling technique is required, and there is a third problem that the assembling cost increases. Note that there is also a method of driving a three-phase motor stably without sensor means such as a Hall element by using sensorless driving. But,
Since the sensorless drive generally uses a back electromotive force detection method, there is a disadvantage that the motor driver circuit becomes complicated and expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has as its object to provide a drive circuit for a polyphase motor in which the number of parts is reduced and cost is reduced.

Another object of the present invention is to provide a drive apparatus for a multi-phase motor that can reduce the size of the motor itself and facilitate the assembly work.

[0010]

According to the present invention, there is provided a driving apparatus for a polyphase motor, comprising: a polyphase motor having a plurality of driving coils;
Detection means provided in the polyphase motor to generate a detection signal corresponding to the rotation speed or rotation phase of the rotor;
Based on the detection signal, a signal processing unit that generates drive signals of different phases corresponding to the drive power applied to all the drive coils, and based on the drive signals of different phases generated by the signal processing unit. A motor drive circuit for sequentially applying drive power having a different phase to each drive coil,
Is provided.

In the above-mentioned multi-phase motor, the detecting means is, for example, a rotating speed detecting means for obtaining a frequency output corresponding to the moving speed of the large number of magnetized parts provided on the rotor. It is.

In the present invention, instead of the rotational speed detecting means (frequency generator; FG), a magnetizing portion for phase detection is provided at one or two places on one circumference of the rotor, and the rotor rotates. Sometimes, a rotation phase detection means (phase generator; PG) for detecting passage of the magnetized portion and obtaining one or two magnetic detection outputs for one rotation of the rotor is used, and the detection output from the rotation phase detection means is used. On the basis of,
A drive signal having a phase corresponding to the drive power applied to each drive coil may be generated.

[0013] The motor of the present invention obtains a detection signal such as FG or PG having a period different from that of a drive signal to be applied to the drive coil, and drives the drive corresponding to all the drive coils based on the detection signal. Since the signal is generated, it is not necessary to provide a dedicated detection means for generating a multi-phase drive signal, such as a Hall element, in the motor, so that the motor can be easily downsized. Further, since it is possible to use the detecting means such as FG and PG, the cost can be reduced. Further, it is not necessary to consider the mounting angle between the Hall elements. Therefore, since complicated work is eliminated, assembling cost can be reduced and work efficiency can be improved.

In order to generate a high-precision coil current, it is preferable that the frequency of the detecting means is high. Is preferred. In this regard, it is preferable to use FG rather than PG.

In the signal processing means of the present invention, a predetermined time is counted based on a detection signal such as FG or PG, and a drive signal to be applied to the drive coil is generated based on the coefficient value. The drive signal can be set with high accuracy, and rotation with stable torque can be always realized.

Further, since a commercially available motor drive circuit can be used, parts can be shared and cost can be reduced.

Further, according to the present invention, even if the driving coil is provided on the rotor side, by obtaining a detection signal proportional to the rotation speed and rotation phase of the rotor,
Motor drive becomes possible.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a multi-phase motor serving as a driven member according to the present invention. In this polyphase motor (three-phase motor) 1, a bearing 4 is fixed on a flat stator substrate 2, and a rotating shaft 5 fixed to an inverted tray-shaped circular rotor 3 is attached to the bearing 4. It is rotatably supported. A coil body 20 is fixed on the stator substrate 2 at a position where the rotor 3 faces. On the surface of the rotor 3 opposite to the stator substrate 2, a turntable 14 for mounting a disk as an information recording medium is fixedly installed.

As shown in the plan view of FIG. 2, the coil main body 20 includes twelve iron core yokes 6 extending in the radial direction and a drive wound around the center line of the yoke 6. And coils for use 7 (7u, 7v, 7w). The multi-phase motor 1 shown in FIG. 2 is for a three-phase motor, for example, in which U-, V-, and W-phase yokes 6 and drive coils 7u, 7v, 7w are arranged in order.

A flexible substrate 11 patterned by etching a copper foil is adhered to the surface of the stator substrate 2 facing the rotor 3. In this pattern, an FG (frequency generator) pattern 12 functioning as a rotation number detection pattern is formed, and the FG pattern 12 is arranged along a rotor magnet 8 formed on the outer periphery of the rotor 3 and described later. Has been established. FIG. 3 shows the FG pattern 12
The upper half of the FG pattern 1 is shown in a plan view.
2, the detection lines 13 extending in the radial direction are arranged at a constant pitch. Adjacent detection lines 13
Outer connection line 13a and inner connection line 13b
And FG pattern 1 as a result.
2 is a zigzag shape.

A rotor magnet 8 is fixed to the inner peripheral portion of the rotor 3. FIG. 4 shows the rotor magnet 8 in a perspective view. In the rotor magnet 8, a driving magnetized portion 9 is formed on a surface facing the tip of the coil body 20, and the rotor magnet 8 faces the FG pattern 12. A rotation speed detecting magnetized portion (FG magnetized portion) 10 is formed on the surface to be rotated. The driving magnetizing section 9 is configured such that N poles and S poles are alternately magnetized at a constant pitch in the circumferential direction, and the rotational speed detecting magnetizing section 10 also has the driving magnetizing section in the circumferential direction. 9
N poles and S poles are alternately magnetized at a constant pitch narrower than the pitch of.

The magnetization pitch between the N pole and the S pole formed on the rotation speed detecting magnetized section 10 is determined by the FG pattern 1
The pitch is the same as the pitch of the two radial detection lines 13. Then, with respect to the number of magnetized poles of the magnetized portion 9 for driving,
The number of magnetized poles of the rotation speed detecting magnetized unit 10 is set to be 3n times (n is an integer). FG pattern 12
And the arrangement phase of the drive coils 7u, 7v, 7w and the arrangement phase of the rotation speed detecting magnetizing unit 10 and the driving magnetizing unit 9. The frequency signal obtained from the FG pattern 12 has a waveform. It is preferable that the rising edge or the falling edge of the shaped signal coincide with the timing of switching the drive power to each drive coil.

A specific configuration for realizing this will be described. As shown in FIG. 9, in the three-phase motor, the U-phase, the V-phase,
The energization switching to each phase of the W phase is performed with a phase difference of 120 °, and the torque generated by the driving motor of each phase is 120 °.
It has a phase difference of °. As shown in FIG. 9, when the drive magnetizing unit 9 moves at a predetermined position (for example, in front of one drive coil), the time (that is, the period) during which the N pole and the S pole (a pair of magnetic poles) pass. T), the coil currents Iu0, Iv
0, Iw0 should be switched six times. Therefore,
The period is set so that the rising edge and the falling edge of the signal (Vfg in FIG. 6A) obtained by shaping the frequency signal from the FG pattern 12 coincide with the timing of switching the coil current six times. Preferably it appears six times during T. This is because the arrangement phase of the FG pattern 12 and each of the drive coils 7u, 7v, and 7w, the arrangement phase of the rotation speed detection magnetization unit 10 and the drive magnetization unit 9, and the rotation speed detection magnetization unit 10 It can be set by determining the magnetization pitch.

Alternatively, a signal obtained by shaping the waveform of the frequency signal from the FG pattern 12 (Vfg in FIG. 6A)
Among them, the number of rising edges or the number of falling edges appears six times during the period T, and the timing of the rising edge or the falling edge coincides with the timing of switching the energization to the driving coil of each phase. May be. Alternatively, the number of appearances of the rising edge and the falling edge of Vfg during the period T may be 12 or 36 (a multiple of 6). In this case, the Vfg is Vfg.
By dividing g by an integral multiple, it is possible to set the timing of switching the energization to the motor of each phase. Alternatively, the period T
6 (A) by causing the edge to appear twice or three times (a factor of 6) and multiplying Vfg.
As shown in FIG. 7, a signal in which an edge appears six times during the period T can be generated.

FIG. 5 is a block diagram showing an embodiment of a driving apparatus for a polyphase motor according to the present invention, and FIG. 6 is a timing chart showing signal processing at the time of steady rotation. (A) shows an FG signal and a driving signal. (B) shows the coil current. FIGS. 7A and 7B are timing charts showing signal processing at the time of startup. FIG. 7A shows an FG signal and a drive signal, and FIG. 7B shows a coil current. When the above-described multi-phase motor 1 is a three-phase motor, it is rotationally driven by a drive circuit as shown in FIG. 5, for example. That is, the output of the FG pattern 12 is output to the FG amplifier 15 via the flexible substrate 11.
The signal is amplified by the waveform shaping means 16 after the signal is amplified by the signal input. Reference numeral 18 denotes a signal processing unit including a computer, a logic circuit, and the like.

In the signal processing means 18, three types of drive signals (Eu, Ev, E
w), and the input terminal H1 of the motor drive circuit 17 is generated.
(+), H2 (+), and H3 (+). A reference voltage Vref is applied to the other input terminals H1 (-), H2 (-) and H3 (-), and is fixed at a predetermined voltage level. Note that this reference voltage Vref is, for example, the motor drive circuit 1
7 is used as a reference voltage for generating a differential signal between the first drive signal Eu, the second drive signal Ev, and the third drive signal Ew. And the motor drive circuit 17
Are connected to the driving coils 7u, 7v, 7w of the three-phase motor, and are supplied with predetermined coil currents Iu, Iv, Iw. Note that the motor drive circuit 17 can use a driver circuit for a normal three-phase motor as it is.

The operation of the drive circuit of the multi-phase motor configured as described above will be described. (Steady rotation mode) When the rotor magnet 8 rotates,
Since the magnetic flux of the rotation speed detection magnetizing unit 10 passes through the detection line 13 vertically, a current is excited in the detection line 13. At this time, the directions of the magnetic flux passing through the adjacent detection lines 13 are opposite to each other, but the directions of the detection lines 13 are also opposite to each other, so that the excited current is unified in one direction. In addition, the N pole and the S pole of the rotation speed detecting magnetized unit 10 alternately face the detection line 13 by the rotation of the rotor magnet 8. Therefore, since the direction of the magnetic flux passing through the detection line 13 is inverted each time, a signal having a frequency proportional to the rotation speed of the rotor is obtained from the FG pattern 12. Vfg in FIG. 6A indicates a signal obtained by shaping the waveform of the frequency signal obtained from the FG pattern 12.

The period of the detection signal obtained from the detection line 13 corresponds to the number of magnetized poles of the rotation speed detection magnetized unit 10 and the pitch of the detection line 13. In the example shown in FIG. 6, the rising edge of the waveform-shaped detection signal (FG signal) Vfg obtained from the FG pattern 12 during the period T in which the N-pole and S-pole of the driving magnetized portion 9 move and The falling edge is set to appear six times. The signal processing means 18 synchronizes the driving signals Eu, Eu, with the falling edge and the rising edge of the FG signal Vfg.
Ev and Ew are switched.

The polarity of the first drive signal Eu is inverted in synchronization with the falling edge, rising edge and falling edge ′ of Vfg, and the second drive signal Eu is inverted.
The polarity of v is inverted at the falling edge, rising edge, and falling edge ′ of Vfg. The polarity of the third drive signal Ew is inverted in synchronization with the rising edge, falling edge, and rising edge ′. By configuring the logic circuit of the signal processing unit 18 in this manner, the second drive signal Ev whose phase is advanced by １ ／ cycle (120 °) with respect to the first drive signal Eu is generated, and the first drive signal Eu is generated. Phase 2 /
A third drive signal Ew advanced by three cycles (240 °) is generated.

The first drive signal Eu, the second drive signal Ev, and the third drive signal Ew generated in this manner.
Is input to the motor drive circuit 17. In the motor drive circuit 17, the coil currents Iu, Iv, Iw are output based on a combination of the H signal and the L signal of the first drive signal Eu, the second drive signal Ev, and the third drive signal Ew.

The combination of the H signal and the L signal of each drive signal Eu, Ev, Ew for one cycle T shown in FIG. 6A and the output of the coil currents Iu, Iv, Iw corresponding thereto are shown in Table 1 below. As shown.

[0032]

[Table 1]

As shown in Table 1 (1) (between sign and sign), the first drive signal Eu is at a low level (hereinafter, referred to as L), and the second drive signal Ev is at a high level (hereinafter, referred to as H). , The third drive signal Ew is L (in this case, Ex =
[L, H, L], the same applies hereinafter) from the motor drive circuit 17, the current in the Iu = − direction, the current in the Iv = + direction, and Iw = 0 (in this case, Ix = “−,
+, 0 ", hereinafter the same). Further, the state of (1) is changed from the state of (2) (sign-
When Ex = [L, H, H], the motor drive circuit 17 outputs each coil current of Ix = “−, 0, +”.

That is, the first, second, and third drive signals Eu, Ev, and Ew are obtained from (1) → (2) → (3) in the above table.
→ (4) → (5) → (6) → (1) → (2)... Therefore, the motor drive circuit 17
Output coil currents Iu, Iv, Iw corresponding to the polarities listed in the above table in accordance with the switching according to the rule. Therefore, each of the motor coils 7u (U phase), 7v (V phase) and 7w (W
6), coil currents Iu, Iv, Iw having regular phase differences as shown in FIG. 6B can always be supplied. That is, it is possible to maintain the constant speed rotation of the three-phase motor.

(Starting Mode) At the time of starting, the output of the FG signal Vfg is 0 because the rotor 3 is not rotating.
Therefore, the signal processing means 18 cannot generate each drive signal based on the FG signal Vfg. Therefore, the pseudo first, second, and third drive signals Eu ', Ev', Ew 'as shown in FIG.
Are generated, and the input terminals H1 (+),
H1 (-), H2 (+), H2 (-) and H3
(+) And H3 (-). In the signal processing means 18, switching of a pulse having a pattern as shown in FIG. 7A is performed in advance in accordance with the characteristics of the three-phase motor to be driven.
7 given.

That is, each drive signal E shown in FIG.
u ′, Ev ′, Ew ′ pulse width Tu1, Tv1, Tw
1 is preset, and when a start command is issued, a pseudo first drive signal Eu 'is set to, for example, an H signal, a second drive signal Ev is set to an L signal, and a third drive signal Ew is set to An H signal (Ex = [H, L, H]: (4) in Table 1) is output, and each drive signal is switched in the order shown in Table 1. Further thereafter, the pulse widths Tu2, Tv2, Tw2 shorter than the above-mentioned Tu1, Tv1, Tw1 and the pulse widths Tu3, T2
The pulse width is gradually shorter, such as v3, Tw3,. As a result, each of the driving coils 7u, 7v, and 7w has the configuration shown in FIG.
As shown in Table 1, the coil currents Iu, Iv, Iw of all combinations of (1) to (6) in Table 1 are given, and the motor can be started at any time. Then, by gradually shortening each pulse width in this way, the rotation of the rotor 3 can be accelerated.

When the rotor 3 rotates to some extent, a pulse current is generated in the FG pattern 12, and the FG signal Vfg is detected. Therefore, after the FG signal Vfg is obtained, the supply of the pseudo drive signals Eu ', Ev', Ew 'is stopped. Then, based on the FG signal Vfg, the first
By generating the drive signal Eu, the second drive signal Ev, and the third pulse signal Ew, it is possible to shift to the steady rotation mode in which a normal rotation control operation is performed. It should be noted that this type of motor is usually provided with a phase generator (PG) for obtaining a pulse output every time the rotor makes a half turn or one turn. This PG
Is set in accordance with the magnetization phase of the drive magnetizing section 9 and the signal obtained from PG is multiplied by an integer, for example, as shown by Vfg in FIG. 9 is generated such that an edge appears six times within a period T in which the N pole and the S pole move, and based on this, the first and second signals are generated.
And the second drive signals Eu, Ev, and Ew.

[0038]

According to the present invention described in detail above, since the switching timing of the drive current to the coil is set using the conventional FG pattern or PG pattern, it is not necessary to use a Hall element. Therefore, the number of parts can be reduced. In addition, since a commercially available motor drive circuit can be used, parts can be shared and cost can be reduced.

Further, since it is not necessary to provide a hall element in the multi-phase motor, the motor itself can be reduced in size and a complicated mounting operation is released.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a polyphase motor,

FIG. 2 is a plan view showing a driving coil arranged in the motor;

FIG. 3 is a partially omitted plan view showing an FG pattern used for a motor,

FIG. 4 is a perspective view showing a rotor magnet used in the motor,

FIG. 5 is a configuration diagram showing a driving device for a polyphase motor according to the present invention;

FIG. 6 shows a timing chart at the time of steady rotation, in which (A) shows an FG signal and an output voltage of the signal processing means,
(B) is a coil current,

FIG. 7 shows a timing chart at the time of startup,
(A) is the FG signal and the output voltage of the signal processing means,
(B) is a coil current,

FIG. 8 is a configuration diagram showing a conventional three-phase motor driving device;

9 shows a timing chart of FIG. 8, wherein (A) is an output voltage of the Hall voltage signal processing means, (B) is a coil current,

[Explanation of symbols]

 Reference Signs List 1 polyphase motor 3 rotor 7u drive coil (U phase) 7v drive coil (V phase) 7w drive coil (W phase) 8 rotor magnet 9 drive magnetic attachment unit 10 rotation speed detection magnetic attachment unit 12 FG pattern ( 13 detection line 15 FG amplifier 16 waveform shaping means 17 motor drive circuit 18 signal processing means Eu first drive signal Ev second drive signal Ew third drive signal Iu, Iv, Iw Coil current (drive power)

Claims (3)

[Claims] 1. A multi-phase motor having a plurality of drive coils, detection means provided in the multi-phase motor for generating a detection signal corresponding to a rotation speed or a rotation phase of a rotor, and a detecting means based on the detection signal. A signal processing means for generating drive signals of different phases corresponding to the drive power applied to all of the drive coils; and a drive signal of different phases generated by the signal processing means. And a motor drive circuit for sequentially providing drive power having different phases. 2. The rotating speed detecting means according to claim 1, wherein said detecting means is a rotating speed detecting means for obtaining a frequency output corresponding to a moving speed of said plurality of magnetized portions provided on said rotor. Of multi-phase motor. 3. The multi-phase motor according to claim 1, wherein the signal processing means counts the number of pulses of the pulse signal detected by the detection means, and generates drive signals having different phases based on the number of pulses. Drive.