JPH03203590A - Starting system and starting controller of sensorless motor - Google Patents

Abstract

PURPOSE:To prevent a rotor from reversely rotating at the time of starting by feeding direct current to respective phases at the same time, to store energy in exciting coils, and by detecting ther difference of the energy, to create control signal in the direction of rotation. CONSTITUTION:When a switch S is turned ON, then via a change-over circuit 6, specification is performed to a full electrification specifying circuit 7, and transistors Q10, Q20 are turned ON, and exciting coils 11, 12 are excited, and energy is stored. When the switch S is turned OFF, then the energy stored in the exciting coils 11, 12 is released, and via resistors r1, r2, current flows. Each energy stored in the coils 11, 12 is different from each other and so each current flowing to the resistors r1, r2 is different from each other, and a difference is generated on input to a comparator 4. From the comparator 4, signal according to the degree of the input is generated, and by a forward rotation signal output circuit, the position of a rotor 2 is known through the signal, and an exciting method necessary for rotating the rotor forward is discriminated, and via a gate circuit 10, the transistors Q10, Q20 are driven.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a starting method and a starting control device for a sensorless DC motor.

(Prior Art) Hall motors using Hall elements have been known as so-called brushless motors. A Hall motor incorporates a Hall element to detect the position of a rotor (rotor pole position, rotor rotation angle).

On the other hand, sensorless motors without such rotor position detection elements have been developed.

In order to rotate these motors in a predetermined rotation direction, it is necessary to control the rotation direction at the time of startup. In the Hall motor described above, the position of the rotor can be detected by the Hall element, and each excitation winding can be driven based on the detection result so that the rotor rotates in a predetermined direction. However, in a sensorless motor, the position of the rotor cannot be detected when the rotor is stopped. Conventionally, the rotor is moved a little in a predetermined step at startup, and the electromotive force generated in the excitation winding due to this small rotation of the rotor is detected to determine the rotor position.Based on this, the rotor moves in a predetermined direction. Each excitation winding was driven to rotate.

Furthermore, as a starting method for sensorless motors,
There is a technique disclosed in Japanese Patent No. 3-69489. In this starting method, a current pulse is sequentially supplied to each of a plurality of excitation windings while the rotor is stopped, and the peak amplitude value of the current pulse is measured and stored. After measurement and storage of peak amplitude values for all excitation windings are completed, the stored maximum amplitude values are read out and compared. Then, according to the comparison result, the rotor is activated so as not to rotate in reverse.

(Problem to be Solved by the Invention) By the way, with the above-mentioned Hall motor, it is easy to control the rotation in a predetermined direction, but since the Hall element is incorporated, it is difficult to miniaturize the motor, and the characteristics of the Hall element may deteriorate at high temperatures. It has the disadvantage of poor high temperature characteristics, such as deterioration of the temperature. Furthermore, if a sensorless motor is started by moving the rotor a little at the time of start-up and detecting the position of the rotor, the rotor may rotate in the opposite direction at the time of start-up. this is,
For example, if it is used to rotate the disk medium of a winchiesta type hard disk drive (one that writes and reads while the head is floating, without making contact with the magnetic medium), the head will be damaged due to reverse rotation. , which is a major drawback.

Furthermore, although the starting method disclosed in Japanese Patent Application Laid-open No. 63-69489 has high reliability because the rotor does not rotate in reverse, it requires a microcomputer, the configuration of the motor drive circuit is complicated, and precision of parts is required. The drawbacks are that it is difficult and the cost is high.

In view of the above-mentioned problems in the conventional example, it is an object of the present invention to provide a starting method and a starting control device for a sensorless motor that does not reverse rotation of the rotor during starting, has high cost performance, and has few starting failures and is highly reliable. With the goal.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a starting method and a starting control device for a sensorless motor according to the present invention include a plurality of soft magnetic bodies and a start control device for each of the soft magnetic bodies. When starting a sensorless multiphase DC motor that has a stator including a plurality of wound excitation windings and a rotor including a permanent magnet, each of the plurality of excitation windings is DC current is simultaneously supplied to the excitation windings to store energy between the terminals of each excitation winding, and the excitation winding is activated based on the difference in energy stored in each of the excitation windings during the rotation suppression period when the DC current is supplied. A predetermined electric characteristic of the wire is detected in a correlated manner, and a rotation direction control signal is generated and outputted so that the rotor rotates in a predetermined direction based on the detected electric characteristic of the excitation winding.

(Function) According to the above starting method or starting control device, each of the excitation windings is controlled so that the rotation of the rotor is temporarily suppressed (stopped) before the normal motor starting period. A rotation suppression period is added in which DC current is simultaneously supplied to the motor. By supplying this direct current, energy is stored between the terminals of each excitation winding. Each excitation winding, which is usually provided in multiple numbers (and the soft magnetic material around which these excitation windings are wound)
are configured to have the same electrical characteristics, but in a sensorless motor, the effective electrical characteristics of each excitation winding vary due to the influence of the magnetic flux of the permanent magnet of the rotor. Therefore, the energy stored in each excitation winding during the rotation suppression period differs for each excitation winding. The present invention correlates a predetermined electrical characteristic of the excitation winding based on this energy difference, and generates a rotation direction control signal so that the rotor rotates in a predetermined direction based on the detected electrical characteristic of the excitation winding. Generate and output.

One of the effective electrical characteristics of each excitation winding that is changed by the influence of the magnetic flux of the permanent magnet of the rotor is the inductance of the excitation winding. If there is a rotor magnetic pole (S pole or N pole) near the soft magnetic material around which the excitation winding is wound, the B-H of the soft magnetic material that is the magnetic core will be affected by the influence of the magnetic flux.
Characteristics are biased. Therefore, the effective inductance of the excitation winding is affected and changes.

When the same direct current is simultaneously supplied to each of the plurality of excitation windings, energy is stored in each of the excitation windings. However, as described above, since the effective inductance of each excitation winding is different, there is a difference in the stored energy. This energy difference causes, for example, the DC current to be cut off and the energy stored in each excitation winding to be released, and at that time, in any of the excitation windings, a current flows in the opposite direction to the DC current. You can know by detecting whether it is flowing. The obtained energy difference indicates the change in the inductance value of each excitation winding due to the influence of the permanent magnet of the stator. Therefore, this allows you to know the positional relationship between the rotor and the stator when the rotor is not rotating (i.e., what starting current will cause the rotor to rotate in the normal direction), and to rotate it in the desired direction. Understand how to apply starting current to the excitation winding.

The difference in energy stored in the excitation winding can be determined by measuring electrical characteristics such as the terminal potential of the excitation winding in addition to the current value of the current flowing through the excitation winding. These electrical characteristics can be accumulated over time and detected using, for example, a capacitor.

(Example) Examples of the present invention will be described in detail below.

First, a method of detecting the rotational direction of the rotor at the time of startup will be explained.

The excitation coil of the motor is formed by winding wire around a soft magnetic material. Normally, each excitation coil is adjusted to have approximately the same B-H characteristics and inductance if the influence of the magnet is ignored. However, when the N or S pole of the rotor approaches the excitation coil, the B-H characteristics of the excitation coil are affected by the magnetic field from the poles, so the effective inductance and hysteresis characteristics differ from the original ones. .

For example, each excitation coil has the polarity of the adjacent pole (N or S
), the strength of the magnetic pole, and the distance to the adjacent pole, the B-H curve will be biased, and the zero (0) level line of the B-H curve will be in phase (U), as shown in Figure 1. , V
, W) (U phase is close to the S pole of the rotor,
W phase is close to N pole). Therefore, when a current flows in a fixed direction, the effective inductance of each exciting coil also differs.

For example, in the two-phase excitation circuit shown in FIG. 2(a),
When the power switch S is turned on, each exciting coil (each phase) L,
The current I, ,I2 flowing through ,L increases exponentially. The N pole of the rotor is in the excitation coil L, and the excitation coil L,!
If the S poles of the rotor are close to each other, then
If the B-H characteristics of each exciting coil L, , L are written symbolically, they become G + , G 2 . therefore,
Each exciting coil L,,L,! The effective inductance of is different from each other, and the stored energy (Lllll'/2
, L, I22/2) are also different from each other.

Next, as shown in FIG. 2(b), the power switch S is opened to release the energy stored in each excitation coil L, L2. At this time, since there is a difference in the energy stored in each exciting coil L, L2, a difference occurs in the current value 11+'2 of the current flowing through each phase, and the terminals PI, P2 of each phase differ.
A potential difference is generated between them, and depending on the energy stored in each exciting coil, a damped oscillating current i with a different polarity is generated in the resistor r.
i2 flows. By detecting and comparing this current difference and potential difference, that is, energy difference, the relative position of the rotor pole with respect to the excitation winding can be detected. Further, by associating the direction of the excitation current with the excitation polarity in advance, the polarity of the magnetic pole can be detected.

The potential difference between the terminals of each phase may be detected by detecting, for example, the potential difference at a certain moment after the power switch is opened.

In addition, as shown in FIG. 2(b), the terminals PI and P2 of each phase
A capacitor C is connected between these terminals P7. The potential difference between P2 (representing the difference in energy stored in each exciting coil) may be detected cumulatively over time. Thereby, it is possible to avoid the effects of noise, variations in coil characteristics, etc., and to perform measurements more accurately.

Furthermore, in place of the capacitor C, an integrating circuit as shown in FIG. 3(a) may be used, or a circuit as shown in FIG. 3(b) that rectifies the current flowing according to the potential difference and holds it in the capacitor. may also be used.

Referring to FIG. 4, a case will be described in which the present invention is applied to a three-phase excitation circuit. In the circuit shown in the figure, switching transistors TA, T, , T, .

Tll is turned on, and each excitation coil a, b is connected from terminal A1.

A voltage for detecting the rotor position shown in FIG. 5 is applied to C. During the period from T1 to T2 in FIG. 5, current in the positive direction flows simultaneously in all excitation coils a, b, and c, and energy is accumulated. At this time, each exciting coil a, b is
, c, the magnetic flux φ1. φ1, φ. Vector illustration of
It will look like Figure 6. As can be seen from this vector diagram, three magnetic fluxes φ4. φゎ and φ cancel each other out, and no rotational force is generated in the rotor.

Next, excitation coils a and b are activated at timing T2.

Let the voltage applied to C be 0. At this time, exciting coil a,
If the energy stored in b, c is released and the transistors TA, Tl], TC, T, are turned on, the resistors r8゜r, , r
, (the resistance value is the same). Since there is a difference in the energy stored in the excitation coils a, b, and c as described above, the potentials of the terminals P4゜P, , P, are different, and by detecting this potential difference, the position of the rotor can be determined. I understand.

FIG. 7 is a block diagram showing a starting and driving circuit for a two-phase sensorless motor according to an embodiment of the present invention. The two-phase sensorless motor shown in the figure consists of a stator 1, a rotor 2, and excitation windings 11 and 12.
Equipped with. 3 is an arrow indicating the direction in which the rotor 2 should rotate (normal rotation direction).

Assume now that the motor is not driving and the rotor 2 is stopped at the position shown in the figure. At this time, the S pole of the rotor 2 is located near the excitation coil 11, and the N pole of the rotor 2 is located near the excitation coil 12, so the B-H characteristics of the six poles of the stator 1 are G, ,G,.

To start the motor, first turn on the switch S.

The timer 5 detects that the switch S is turned on and sends a switch-on detection signal to the switching circuit 6. The switching circuit 6 is
In response to this, a signal is sent to the full conduction instruction circuit 7 to activate it.

The full conduction instruction circuit 7 instructs the gate circuit 10 to make the switching transistor Q l ll+ Q 20 fully conductive. In response to this, the gate circuit 10 switches the switching transistors Q,. Supply a base voltage that turns on IQ20 at the same time. As a result, an excitation current is supplied from the power source E to the excitation coil 1 through the resistor r1 and the transistor Q10, and energy is stored.

At the same time, an excitation current is supplied from the power supply E to the excitation coil 12 via the resistor rh (same resistance value as the resistor r) and the transistor Q 20, and energy is stored.

At this time, as described above, the magnetic fluxes of the excitation coils 11 and 12 cancel each other out, and no rotational force is generated in the rotor 2.

Also, the B-H characteristic G1 of the six poles of the stator 1. Due to G2, the excitation coil 11 has less stored energy than the excitation coil 12.

Next, switch S is turned off. At this time, gate circuit 1
The base voltage from 0 is kept supplied, and the switching transistor Q + O+ 020 is kept on. As a result, the energy accumulated in the excitation coils 11 and 12 is released, and the resistances rl+r2 and l' are released, respectively.
Current flows through transistor Q ln+ 0211. Due to the above-mentioned energy difference, the current flowing through the resistor r1 is different from the current flowing through the resistor r2, and therefore a potential difference is generated between the terminals of the capacitor C1, and charges are accumulated.

By repeating on/off of the switch S as described above an appropriate number of times, the potential difference between the terminals of the capacitor C1 is detected cumulatively over time. That is, both terminals of capacitor C3 are input to comparator 4, and the comparison result (10/-
signal) is input to the normal rotation signal output circuit 8. The normal rotation signal output circuit 8 receives the +/- signal from the comparator 4 (rotor N
, representing the position of the S pole), a normal rotation signal is output to the gate circuit 10 so that the rotor rotates in a predetermined direction 3.

The timer 5 sends a signal to the switching circuit 6 after a predetermined period of time (sufficient time for the normal rotation signal to be output), and the switching circuit 6 receives this and disables the output of the full conduction instruction circuit 7. Then, the normal rotation signal output of the normal rotation signal output circuit 8 is enabled. Thereby, the gate circuit 10 inputs the normal rotation signal and turns on/off the transistor Q I LlI Q 20 based on this.

As described above, the motor is started in a predetermined direction. After startup, the normal rotation signal output circuit 8 outputs the transistor Q I Ll via the gate circuit based on the signal from the sensorless signal circuit 9.
IQ20 is turned on and off and the motor continues to rotate in the normal direction.

FIG. 8 shows a circuit diagram of a sensorless motor starting and driving device according to a second embodiment of the present invention.

The device in the figure has three excitation coils Lu, Lv, and Lw.
The present invention is applied to a phase (u, v, w) sensorless motor.

When the power is turned on, the energization switching circuit 23 instructs the phase switching circuit 23 that the phase current shown in FIG. 5 should be supplied to each phase.
5. In accordance with this instruction, the phase switching circuit 25 switches Darlington-connected transistors Q, , Q3 . Q, and transistor Q2. Q4. Outputs a signal instructing Q6 to turn off. The control circuit 27 controls the base voltage of each transistor in response to this signal, turning each transistor on and off, and also turns on the transistor Q7.

As a result, the transistor Q1 and the excitation coil Lu.

Power supply E via resistors R, I and transistor Q7
Current is supplied from Similarly, exciting coil Lv,
Current is also supplied to Lw. Therefore, exciting coil L
The current shown in FIG. 5 flows through u, Lv, and Lw, but as described above, this current does not generate rotational torque in the rotor.

On the other hand, after the power is turned on, a reference clock is generated from the clock generator 21, and the ring counter 22 counts this reference clock and instructs the energization switching circuit 23 that a predetermined period of time has elapsed. In response to this, the energization switching circuit 23 switches the excitation coils Lu and Lv.

Instructs the phase switching circuit 25 to stop supplying current to Lw. In accordance with this instruction, the phase switching circuit 25 switches the Darlington-connected transistors QQ3 . Q, and transistor Q2. Q.

Outputs a signal instructing Q6 to turn off. The control circuit 27 controls the base voltage of each transistor according to this signal, and controls all the transistors Q1 to Q7 . At the same time, transistor Q7 is also turned off.

As a result, the energy stored in the excitation coils Lu, Lv, and Lw is released, and current flows through the resistors R, , R2, and R3 based on the difference in the stored energy. Resistance R,,R, due to this current.

The potential difference between each terminal of R3 is the capacitor C,,C
2. Charge C3.

By repeating the above operation, the capacitors C+, C2, and C'+ have sufficient charge for reliable detection.1. : Once accumulated, the comparators CPI, CP2. CP3 detects this. The detection result is input to the rotation direction detection circuit 29, and the rotation direction detection circuit 29 outputs a rotation direction instruction signal to the phase switching circuit 25 based on this result. Phase switching circuit 25
Based on this rotational direction instruction signal, the phase is switched and startup is started so that the rotor starts rotating in the desired direction without rotating in reverse.

When the rotor starts rotating, a back electromotive force is generated in the excitation windings Lu, Lv, and Lw of each phase due to the rotation of the rotor. This back electromotive force is supplied to comparators C0M1 to C0M3. In response to this back electromotive force, the comparator COMI
C0M3 outputs a signal corresponding to the rotational position of the rotor. The output signals from the comparators COMI to C0M3 are delayed by a predetermined angle by the delay circuit 31 and supplied to the energization switching circuit 23. The energization switching circuit 23 is a delay circuit 31
The current of each phase during the start-up period is switched according to the signal supplied from the start-up period.

As described above, the motor is started without being reversed.

After the startup period ends, a pause period is placed.

After the pause period, there is a commonly known acceleration period.

During this acceleration period, the energization switching circuit 23 outputs a phase current switching signal to switch the phase current so as to accelerate the rotational speed of the rotor. In response to this instruction signal, the phase switching circuit 25, control circuit 27, etc. operate to turn on/off the transistors Q1 to Q7, and the phase currents are switched and energized. As a result, the rotor gradually becomes faster.

According to the output signal from the delay circuit 31, when the rotation speed of the rotor reaches a predetermined percentage (for example, 95%) of the rated rotation speed, the normal rated rotation period begins.

During this period, the energization switching circuit 23 instructs to supply the phase current so that the rotor rotates in the rated state. In response to this instruction, the phase switching circuit 25 and the control circuit 27
etc., the transistors Q1 to Q7 are turned on and off, and the phase current is supplied while being switched. This causes the rotor to rotate at a substantially constant speed.

Although the above embodiments have been explained using examples of 2-phase or 3-phase motors, the present invention is not limited thereto, and can also be applied to DC sensorless morphs such as 6-phase and 12-phase motors. can.

Furthermore, it goes without saying that other applications fall within the scope of the claims of the present invention, as long as the position and polarity of the magnetic pole are determined based on the accumulation of energy in a soft magnetic material and its function.

[Effects of the Invention] As explained above, according to the present invention, the same DC current is simultaneously supplied to each phase of a sensorless motor to accumulate energy in the excitation coil, and the difference in this energy is detected to control the rotation direction. Since the signal is generated, the rotor does not rotate in reverse during startup and can always be rotated in the desired direction. In addition, since it is not a complicated circuit, it has high cost performance, and has low startup failures and high reliability.

[Brief explanation of drawings]

Figure 1 is a diagram to explain the influence of the rotor poles on the excitation coils, Figure 2 is a circuit diagram to explain the principle of rotor rotation direction detection, and Figure 3 is a diagram to explain the influence of the rotor poles on the excitation coils. FIG. 4 is a circuit diagram showing another example of detecting accumulated energy over time and cumulatively; FIG. 4 is a circuit diagram showing an example in which the present invention is applied to a three-phase excitation circuit; FIG. 6 is a diagram showing the magnetic flux generated by the excitation current shown in FIG. 5. FIG. 7 is a diagram showing the magnetic flux generated by the exciting current shown in FIG. FIG. 8 is a circuit diagram of a sensorless motor starting and driving device according to a second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Stator (stator), 2... Rotor (rotor), 3... Forward rotation direction, 5... Timer, 6... Switching circuit, 7... Full conduction instruction circuit, 8... Normal rotation signal output circuit, 10... Gate circuit, 11.12... Excitation winding, G1゜G2... B-H characteristic, S... Switch,
Q. , G12...transistor, E...power supply, r
l, r2...resistance. C1... Capacitor, 23... Energization switching circuit, 25
. . . Phase switching circuit, 27 . . . Control circuit, 29 . . . Rotation direction detection circuit, 31. --Delay circuit 1, Lu, Lv
, Lw-・Excitation coil, R1-R4...Resistance, Q, ~
Q7...Transistor, C1-C3...Capacitor, CP1-CP3...Comparator. Figure 1

Claims (6)

[Claims] (1) A starting method for a sensorless multiphase DC motor having a stator including a plurality of soft magnetic bodies and a plurality of excitation windings wound around each of the soft magnetic bodies, and a rotor including a permanent magnet. At startup, a direct current is simultaneously supplied to each of the plurality of excitation windings so that rotation of the rotor is suppressed, energy is stored between terminals of each excitation winding, and the direct current is supplied. A predetermined electrical characteristic of the excitation winding is detected in a correlated manner based on a difference in energy stored in the excitation winding during a rotation suppression period during which the excitation winding is suppressed; A method for starting a sensorless motor, characterized in that a rotation direction control signal is generated and outputted so that the rotor rotates in a predetermined direction. (2) Detection of the electrical characteristics is repeated multiple times upon startup, the detected values obtained from the multiple detections are accumulated or held over time, and the rotation direction is controlled based on the cumulatively held results. 2. The sensorless motor starting method according to claim 1, wherein a signal is generated and output. (3) Correlative detection of predetermined electrical characteristics of the excitation windings is performed by cutting off the DC current supplied to each excitation winding during the rotation suppression period of the rotor and storing energy in each excitation winding. and detecting in which of the excitation windings a current flows in a direction opposite to the direct current when the energy is released, and based on the detection result, the rotor 3. The sensorless motor starting method according to claim 1, wherein the rotation direction control signal is generated and outputted so as to rotate in a predetermined direction. (4) Start-up control device for a sensorless multiphase DC motor that has a stator that includes a plurality of soft magnetic bodies and a plurality of excitation windings wound around each of the soft magnetic bodies, and a rotor that includes a permanent magnet. DC current supply means for simultaneously supplying DC current to each of the plurality of excitation windings to store energy between terminals of each excitation winding so that rotation of the rotor is suppressed upon startup; Electrical characteristics that correlatively detect predetermined electrical characteristics of the excitation winding based on a difference in energy stored in the excitation winding during a rotation suppression period during which DC current is supplied by the DC current supply means. and a means for generating and outputting a rotation direction control signal so that the rotor rotates in a predetermined direction based on the electrical characteristics of the excitation winding obtained by the electrical property detection means. Features: Sensorless motor startup control device. (5) The supply of DC current to the excitation winding by the DC current supply means and the detection of the electric characteristics by the electric characteristic detection means are performed multiple times during startup, and the means for generating and outputting the rotation direction control signal is 5. Starting the sensorless motor according to claim 4, wherein detection values obtained through multiple detections are cumulatively held over time, and the rotation direction control signal is generated and output based on the cumulatively held results. Control device. (6) The means for detecting the electrical characteristics in a correlated manner interrupts the DC current supplied to each of the excitation windings during the rotation suppression period of the rotor to release the energy stored in each of the excitation windings, The means for detecting in which of the excitation windings a current flows in a direction opposite to the direct current when the energy is released, and generating and outputting the rotation direction control signal, Based on the result, the rotation direction control signal is generated and outputted so that the rotor rotates in a predetermined direction.
The sensorless motor starting control device described in .