JPH08214584A - Motor with speed controller - Google Patents

Abstract

PURPOSE: To control and suppress high frequency rotation unevenness and reduce the speed fluctuation caused by the fluctuation of a load. CONSTITUTION: A motor has a speed detection means which detects physical values corresponding to the speed of the motor, a speed control means 20 which controls the speed of the motor in accordance with the output signal of the speed detection means and a driving circuit 21 which drives the motor to rotate in accordance with the output of the speed control means 20. In the motor, a permanent magnet 13 which is provided in a rotor and has a plurality of poles, AC signal generating windings which are so provided on a stator as to face the poles and generates a plurality of AC signals having phases different from each other in accordance with the change of poles and a calculating means 19 which calculates the AC signals are provided and the speed of the motor is controlled in accordance with the output of the calculating means 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor provided with a speed control device, and more particularly to a motor which controls a motor with a speed signal having a small dead time and a small ripple, and has a high stability of speed with less uneven rotation. The present invention relates to a motor equipped with.

[0002]

2. Description of the Related Art FIG. 9 is a block diagram of a motor having a conventional speed control device. The rotor 1 is provided with a permanent magnet for frequency power generation that has a magnetic pole of 2p (a positive integer equal to or greater than p wave 1) poles, and the stator is opposed to the magnetic poles at a predetermined interval and is close to the magnetic poles. AC signal generating windings 2 for generating an AC signal in accordance with the change of P are provided on the printed board as p folded copper foil wirings.

That is, as shown in FIG. 10, the winding 2 has a shape having the same number of radial power generating wire elements 2a as the magnetic poles, which are formed at the same pitch as the magnetic pole pitch of the permanent magnet for frequency power generation. It is a comb-shaped conductive pattern formed in a ring shape.

The winding 2 outputs a voltage signal e (t) as shown in the equation (1) as the rotor 1 rotates.

E (t) = K × n × sin (2π × p × n × t) (1) k: proportional constant n: rotational speed p: number of pole pairs t: time K is determined by the shape of the constituent elements It is a constant of proportionality and is constant if the motors are the same, and since the amplitude and frequency are proportional to the rotation speed, for example, if the peak value of this signal is processed and output by the sample hold circuit 3, a speed voltage proportional to the speed can be obtained. To be

The output speed voltage of the sample and hold circuit 3 is compared with a reference voltage preset by the speed control means 4, and a signal corresponding to the difference between the output speed voltage and the reference voltage is supplied to the drive circuit 5. By configuring so as to control the torque of the motor, the speed of the motor is balanced and kept constant at a speed at which the output speed voltage of the sample hold circuit 3 becomes substantially equal to the reference voltage.

That is, assuming that the reference voltage is Es, equation (2)
Equilibrate at a speed Ns such as

Ns = Es / K (2) FIG. 6 is a timing chart for explaining these processes.

[0009]

By the way, the conventional method for sampling and holding the peak value of the power generation signal as shown in FIG. 11a of the AC signal generating winding 2 to obtain the speed voltage of FIG. 11b is a moment of sampling timing. However, the speed fluctuation of a cycle shorter than the repetition cycle of the peak value cannot be detected.

That is, since the speed fluctuation of a frequency higher than the frequency of the power generation signal cannot be detected, and there is a dead time of a time approximately equal to the cycle of the power generation signal, which causes a phase lag, the speed is changed at this speed voltage. When configured to control,
There is a problem that uneven rotation at a frequency higher than about 1/8 of the frequency of the power generation signal cannot be controlled and the speed fluctuation due to load fluctuation becomes large.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and includes speed detection means for detecting a physical value corresponding to the rotation speed of a motor, and speed of the motor according to the output signal. In a motor provided with a speed control means for controlling and a drive circuit for rotationally driving the motor according to the output of the speed control means, a permanent magnet having a multi-pole magnetic pole arranged on a rotor and facing the magnetic pole. As described above, it is provided with an AC signal generating winding which generates a plurality of AC signals having mutually different phases according to the change of the magnetic poles, and an arithmetic means for arithmetically operating the AC signal. A motor having a speed control device configured to control the speed of the motor is provided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a motor having a speed control device according to the present invention will be described in detail below with reference to FIGS.

An embodiment of the present invention will be described. FIG.
Is a block diagram for explaining the outline of the present invention, FIG. 2 is a timing chart thereof, and FIG. 3 is an exploded view of a disk drive motor embodying the present invention.

First, a schematic structure of a disk drive motor embodying the present invention will be described with reference to FIG.

In FIG. 3, a rotor 10 provided with a rotation shaft (not shown) has a center hub (not shown) for driving a floppy disk (not shown) to rotate integrally therewith.

The rotor 10 has a north pole and an S pole in the flange 11.
An annular driving permanent magnet 12 having driving magnetic poles of, for example, 8 poles, which are alternately magnetized, is arranged, and a multi-pole magnetized permanent magnet for frequency power generation is provided on the outer periphery of the flange 11. 13 is fitted.

On the other hand, on the stator base 14, three-phase drive coils (armature coils) 15a, 1 which face the above-mentioned permanent magnet 12 at a predetermined interval and maintain a predetermined positional relationship.
5b, 15c and three Hall elements 16a, 16b, 16c arranged at an electrical angle of 120 degrees are arranged respectively. Further, the stator base 14 has a comb-teeth-shaped AC signal generating winding 18 which is arranged in a pattern and is opposed to the permanent magnet 13 for forming the frequency power generation with a predetermined space therebetween.

FIG. 5 shows a first example of the AC signal generating winding of the embodiment of the present invention, and the difference will be described in comparison with the conventional one shown in FIG. The winding 18A shown in FIG. 5 is a radial power generating wire element 18A1a formed at equal intervals with the magnetic pole pitch.
Is a comb-shaped conductive pattern formed in an annular shape having the same number of magnetic poles, and is divided into two parts, an upper half and a lower half, which form independent windings 18A1 and 18A2. There is a 90 degree shift, and AC signals having a phase difference of 90 degrees are generated as the motor rotates.

FIG. 6 shows a second example of the AC signal generating winding of the embodiment of the present invention. The AC signal generating winding 18B is composed of windings 18B1 to 18B4 which are divided into approximately 90 degrees, and the center of the winding is sandwiched. Two windings 18B1 and 18B facing each other
3 is in phase and is connected in series, so 2
The windings of the group are configured to generate an AC signal having a phase difference of 90 degrees with the rotation of the motor. Compared to the example of FIG. 5, this example suppresses the fluctuation of the power generation output of the winding to a small value with respect to the surface runout fluctuation of the multi-pole permanent magnets arranged in the rotor, and the difference between the power generation outputs of the two windings. Has a characteristic that becomes smaller. This feature becomes more effective by increasing the number of divisions.

The shaft of the rotor 10 is rotatably supported by bearings 17 on the stator base 14 to form a direct drive type spindle motor. The rotor 10 includes a field magnetic field, a drive coil, a Hall element,
It rotates according to the well-known principle of a Hall brushless motor that interacts with a drive circuit.

The operation will now be described with reference to the block diagram shown in FIG.

Reference numerals 18A1 and 18A2 are AC signal generating windings for generating AC signals A and B having a sinusoidal shape and having a phase difference of π / 2 with each other with substantially equal amplitude and frequency proportional to the measured speed. The AC signals eA (t) and eB (t) are expressed by the following equations, respectively.

EA (t) = K × n × sin (2π × p × n × t) (3) eB (t) = K × n × sin (2π × p × n × t + π / 2) (4) ) K: proportional constant n: rotational speed p: number of pole pairs t: time These are shown by the waveforms a and b shown in FIG.

The calculating means 19 to which the AC signal generated by the AC signal generating windings 18A1 and 18A2 is supplied is configured to always obtain an output corresponding to the peak value K × n from these AC signals eA (t) and eB (t). First, the instantaneous value eA
From the ratio of (t) and eB (t), n × t is calculated by the equation (5). n × t = arctan (eB (t) / eA (t)) / (2π × p) (5) Next, the peak value K × n is calculated from n × t by the equations (6) and (7). . K × n = eA (t) / sin (2π × p × n × t) (6) K × n = eB (t) / sin (2π × p × n × t + π / 2) (7) Either Although it has been shown that the peak value can always be obtained from two instantaneous values by calculation, there is a concern that the error may increase at the timing when the absolute value of the instantaneous value is small. In this case, the two instantaneous values of eA and eB There is no problem by a method such as selecting and using one with a higher absolute value. In this way, the calculating means 19 outputs a peak value from the instantaneous value of the AC signal by the two windings 18A1 and 18A2, or a voltage (g in FIG. 2) of a magnitude corresponding to this peak value as the speed signal voltage. The calculating means 19 may perform an analog-to-digital conversion of the instantaneous value and then perform a software operation with a microprocessor, or an arithmetic processing with a hardware logic circuit as it is as a digital signal. The object can be achieved by combining after conversion by the function conversion circuit or by appropriately combining these.

Next, the output speed voltage of the calculation means 19 is compared with a reference voltage preset by the speed control means 20 and supplied to the drive circuit 21, and according to the difference between the output speed voltage and the reference voltage. If configured to control the torque of the motor. Similar to the conventional example, the speed of the motor is balanced and controlled at a speed such that the output speed voltage of the calculating means 19 becomes substantially equal to the reference voltage. With this configuration, the motor speed can be detected continuously, speed fluctuations with a frequency higher than the power generation signal can be detected, and phase delay due to dead time is small, so high-frequency rotation irregularities can be controlled and suppressed, and speed fluctuations due to load fluctuations are small. Features such as being able to be obtained.

Now, the second calculation procedure of the calculation means 19 will be described. The AC signals A and B described above can be regarded as a rotation vector represented by two pieces of information of magnitude and phase, as shown in FIG.

The relation between the instantaneous values of the two AC signals A and B and the vector at an arbitrary phase angle θ is shown in this figure, and the two vectors are equal in magnitude and have a phase difference of 90 °. The instantaneous value is taken as the length of the perpendicular drawn down the x-axis. Each triangle formed by this vector and the perpendicular is congruent because the two sides of the triangle are equal. From these, this triangle forms a right-angled triangle whose two instantaneous values are two sides sandwiching a right angle and whose vector size is the hypotenuse. Here, from the Pythagorean theorem, the square of the magnitude of the hypotenuse vector is given as the sum of the squares of the instantaneous values of the two sides that sandwich the right angle.
That is, it is shown that the crest value K × n, which is the magnitude of the vector, is obtained as a square root of the sum of the squares of the two instantaneous values eA and eB by calculation as in equation (8).

K × n = (eA (t) ² + eB (t) ² ) 1/2 (8) The calculating means may perform analog-to-digital conversion of the instantaneous value and then software-calculate it by a microprocessor. Alternatively, the digital logic signal may be processed as it is by a hardware logic circuit, or the analog signal may be converted after being converted by the function conversion circuit, or may be combined, and the object may be achieved by appropriately combining these.

FIG. 4 shows an embodiment of a circuit for obtaining a voltage corresponding to a peak value by performing function conversion of an analog signal as it is and performing a calculation corresponding to the equation (8). The AC signal eA generated from the winding 18A1 is the operational amplifier A1 and the transistor Q.
The current is converted into an absolute value by 1, 2, 5, 6, 7 and the resistor R1 and converted into an absolute value, and becomes Ia as shown in the waveform of FIG.
It flows through the diode composed of 3 and 4, and it is converted into a voltage Vd corresponding to a logarithm by utilizing its current-voltage characteristic.

Vd = 2 × h × ln (Ia / Is) = h × ln (Ia / Is) ² (9) h: Semiconductor-specific constant Is: Dark current of diode Transistor Q8 biased by constant current Ir After the voltage shift at, the current inversely logarithmically converted by the current-voltage characteristic of the transistor Q9 flows through the collector as shown in the waveform of FIG. 2e.

Similarly, the AC signal eb generated from the winding 18A2 is the operational amplifier A2 and the transistors Q14,1.
5, 18, 19, 20 and the resistor R4 convert the current into an absolute value and form Ib as shown in the waveform of d in FIG.
After flowing into the diode composed of 16 and 17, and further voltage-shifted by the transistor Q21 biased by the constant current Ir, the current inversely logarithmically converted by the current-voltage characteristic of the transistor Q22 has a collector-like waveform as shown in FIG. 2f. Flow to. The current obtained by combining these is Io.

Io = Ia ² / Ir + Ib ² / Ir (10) As a result, a current corresponding to the sum of the squares of Ia and Ib is obtained as shown in Expression (10). In this way, the currents corresponding to the two instantaneous values are squared and the sum thereof is obtained to obtain the current corresponding to the square of the peak value. By performing the above-mentioned reverse processing (square root calculation) by the transistors Q10 to 13, the square root of the sum current, that is, the speed voltage corresponding to the peak value is obtained as the voltage drop of R3 as indicated by g in FIG. Further, the output speed voltage is set to a reference voltage E preset by the speed control means composed of A3, R7, 8 and C2.
By comparing with s and supplying to the drive circuit 20 composed of A4, Q23 and R6 so as to control the torque of the motor according to the difference, the speed of the motor becomes equal to the reference voltage at the output speed voltage of the calculating means. Equilibrate at such a speed and the speed is controlled to be constant.

In the above description, the AC signal is a two-phase signal which is a sine wave and has a phase difference of π / 2 substantially in electrical angle. However, not limited to this, for example, a three-phase signal can be calculated from an instantaneous value. The peak value is continuously obtained, and the same effect is obtained.

Further, even if the AC signal contains odd harmonics, the sum of squares thereof is also constant, so that it does not hinder the operation of the present invention.

In the above description, the power generation output of each independent winding is directly input to the calculating means. However, the plurality of power generation outputs are appropriately sum-combined or difference-combined to adjust the phase and amplitude and then calculated. It is also possible to input to the means,
In this case, you can combine two-phase signals from three-phase power generation signals,
A configuration in which a three-phase signal is synthesized from a two-phase power generation signal is also possible.

Further, in the case where a plurality of power generation signals have a difference in amplitude, the calculation means includes a correction function for correcting the difference in amplitude, whereby a calculation error is reduced, so that more advanced control becomes possible.

In the present embodiment, an example in which the motor speed is controlled only by the output voltage of the calculating means 19 has been described.
As shown in FIG. 3, the speed signal obtained by converting the output signal of the AC signal generating winding 18 or the output signal of the separately provided frequency generator into a so-called FG signal, the frequency and period of which are converted by the frequency voltage converting means 22, Further, a known speed control method for controlling the speed of the motor in accordance with the phase voltage obtained by converting the phase difference between the reference frequency signal and the above-mentioned FG signal by the phase voltage converting means 23 is the calculating means according to the present invention. Even if the configuration is such that the output voltage is added to control the speed of the motor, it does not depart from the scope of the claims, and the effect of detecting speed fluctuations of a frequency higher than the power generation signal peculiar to the present invention is lost. The effect obtained by that is also obtained.

That is, the above-mentioned phase voltage is a control voltage effective for long-term fluctuations in the speed fluctuations of the motor, and the frequency speed voltage is a cycle shorter than that and a speed equal to or lower than about 1/8 of the frequency of the power generation signal. Since the control voltage is effective for fluctuations, and the operation speed voltage according to the present invention is also effective for speed fluctuations at a higher frequency, the operation speed voltage according to the present invention is added to these known control voltages. If the motor speed is controlled by combining them appropriately, the effect peculiar to the present invention can be obtained in addition to the known speed control.

[0039]

As described above, according to the present invention, the speed of the motor can be continuously detected, the speed fluctuation of a frequency higher than the power generation signal can be detected, and the phase delay due to the dead time is small, so that the rotation irregularity of the high frequency is small. It is possible to provide a motor equipped with a speed control device that highly stabilizes the speed of the motor, such that the control can be suppressed and the speed fluctuation due to load fluctuation can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a motor including a speed control device of the present invention.

FIG. 2 is a timing chart of FIG.

FIG. 3 is a schematic configuration diagram of a disk drive motor embodying the present invention.

FIG. 4 is a specific circuit diagram of FIG.

FIG. 5 is a diagram of a first embodiment of an AC signal generating winding used in the present invention.

FIG. 6 is a diagram of a second embodiment of an AC signal generating winding used in the present invention.

FIG. 7 is a vector diagram showing an AC signal in terms of magnitude and phase difference.

FIG. 8 is a block diagram showing another embodiment of the motor including the speed control device of the present invention.

FIG. 9 is a block diagram of a motor including a conventional speed control device.

10 is a winding for forming frequency power generation in FIG.

11 is a timing chart of FIG.

[Explanation of symbols]

18 ... AC signal generating winding, 19 ... Arithmetic means, 20 ... Speed control means, 21 ... Drive circuit, 22 ... Frequency voltage converting means, 23 ... Phase voltage converting means.

Claims (4)

[Claims] 1. A speed detection means for detecting a physical value according to the rotation speed of the motor, a speed control means for controlling the speed of the motor according to the output signal, and a motor according to the output of the speed control means. In a motor provided with a drive circuit for rotational driving, a permanent magnet having a multi-pole magnetic pole arranged on a rotor and a plurality of permanent magnets arranged on a stator so as to face the magnetic pole and having different phases according to changes in the magnetic pole. Of the AC signal generating coil for generating the AC signal of the above, and a calculation unit for calculating the AC signal, and configured to control the speed of the motor according to the output of the calculation unit. With a motor. 2. The AC signal has a substantially sinusoidal waveform,
2. The motor having a speed control device according to claim 1, wherein the arithmetic means synthesizes and outputs a signal substantially proportional to the square of the input signal. 3. The AC signal has a substantially electrical angle of about π /.
The motor having the speed control device according to claim 2, wherein the motor is a two-phase signal having a phase difference of two. 4. A motor provided with a speed control device according to claim 1, wherein the arithmetic means is provided with a correction means for correcting the waveform of the AC signal.