JPH06178580A - Method for starting sensorless multiphase dc motor - Google Patents

Abstract

PURPOSE:To improve start probability by providing the first acceleration process for controlling the excitation pattern geared to the rotational position of a rotor based on counter electromotive voltage between first and second stepping processes, and supplying an exiting current with the inside step pattern where the second step process has skipped by one in backward or forward direction from the final excitation pattern of the first acceleration process. CONSTITUTION:A controller 2 performs the control of start of a motor and the stationary operation after start, based on the signal of a counter electromotive voltage detecting circuit 1. That is, in the first step process, a stator coil is excited, according to the specified pattern. Next, the first acceleration process is performed for controlling the excitation pattern, according to the rotational position of a rotor. And, the second step process is performed, adding 2 to the count value of a counter representing the final excitation pattern of the first acceleration process, whereby it gets in the condition that it has skipped by one, and reverse excitation drive to reverse the exciting current from negative to positive is executed. And, when the second step process is executed, it enters the second acceleration process, and then the fixed speed process is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for starting a sensorless multi-phase DC motor, and more particularly to a technique for improving the reliability of the starting.

[0002]

2. Description of the Related Art Conventionally, a brushless polyphase DC motor has been used as a motor for rotating a magnetic disk drive. This kind of motor is also called a spindle motor, and for example, a stator including a stator coil that generates a magnetic field in an excited state, and a rotor including a rotor magnet that obtains a rotational force by electromagnetic interaction with the magnetic field of the stator coil. , A structure having a sensor for detecting the rotational position of the rotor magnet is well known,
In the spindle motor with such a structure, in many cases,
Rotation control is performed by an electronic circuit formed into a semiconductor chip.

In this case, the magnetic field generation timing on the stator side is controlled by detecting the rotational position of the rotor magnet by a sensor, and a Hall element has been conventionally used for this type of sensor. However, in recent years, in order to avoid downsizing of motors and deterioration of sensor characteristics, so-called sensorless multi-phase, which detects the position of the rotor magnet by using the induced voltage generated in the coil during the rest without using the sensor. DC motors are becoming popular.

At the time of starting the sensorless motor, when the motor is stopped, a counter electromotive voltage cannot be obtained, so that the rotor is first oscillated. For example, in a three-phase coil spindle motor, a step process of sequentially supplying an exciting current to a stator coil is repeated, and during this step process,
Normally, there is included a step of supplying a positive direction, a pause, and a reverse direction of exciting current to each phase, and a magnetic field generated by causing a predetermined pattern of exciting current containing such steps to flow between the rotor magnet and The driving torque is generated by the attraction and repulsive force between them, and the motor is started.

However, such a sensorless polyphase DC motor has a technical problem to be described below, particularly in its starting method.

[0006]

That is, in the above sensorless multi-phase DC motor, the position of the rotor magnet is detected by the induced voltage due to the magnetic flux interlinking with the coil, but there is no induced voltage when the motor is stopped. Also,
Since the polarity of the magnet is unknown, it is forced to start when starting. However, depending on the position of the rotor, a start failure may occur due to low torque, or a magnetic field due to energization may occur in the opposite direction, causing a reverse rotation of 60 degrees or more at the start-up.

Therefore, in order to avoid such an inconvenience and improve the starting reliability, the present applicant has developed a starting method in which a part of the stepping is a double drive system. In this starting method, at the time of starting the sensorless motor, the starting method includes a reverse excitation drive operation in which the energization direction is reversed from positive to negative or from negative to positive without including a down time, and according to this method, A large variation range of the magnetic flux density is generated, the dead point of starting is eliminated, high torque is generated, and starting reliability is improved.

However, in such a double drive system, normally, after the first step of supplying an exciting current to the stator coil in a predetermined internal step pattern, the same internal step as described above is performed in the step of second step. Since the excitation current is supplied in the stepwise pattern and the reverse excitation drive operation is obtained in the initial stage of the second step, even if the motor does not start at all in the first step, the second step is performed. The reverse excitation drive operation is performed in the early stage of the advancing process and the probability of starting is very large. For example, when the motor swings in the first step, the first acceleration process immediately after that, that is, the back electromotive voltage In the process of changing and controlling the excitation pattern in accordance with the rotor position detected in step 6, if the excitation pattern changes, the reverse excitation drive operation may not be performed reliably in the initial stage of the second step process, and the starting probability There is room for improvement in terms of Was Tsu.

The present invention has been made in view of the above problems, and an object thereof is to ensure that the reverse excitation drive operation is performed in the second step process. It is an object of the present invention to provide a method for starting a sensorless multi-phase DC motor that can improve the starting probability.

[0010]

In order to achieve the above object, a first aspect of the present invention rotates by a magnetic interaction between a stator having a stator coil for generating a current magnetic field in an excited state and the current magnetic field of the stator coil. A rotor provided with a rotor magnet for obtaining a force, a counter electromotive voltage detection circuit for detecting an induced electromotive voltage of the stator coil, and an exciting current supplied to the stator coil in a predetermined internal step pattern.
And a second stepwise step, the method of starting a sensorless multi-phase DC motor is based on a counterelectromotive voltage from the counterelectromotive voltage detection circuit between the first stepwise step and the second stepwise step. A first acceleration step for controlling an excitation pattern according to the rotational position of the rotor is provided, and the second step is an internal step pattern skipped one by one in the front-back direction from the final excitation pattern of the first acceleration step. An exciting current is supplied to the stator coil.

In the first invention, a current holding step for maintaining the final internal step of the first step is provided in place of the first acceleration step, and the second step is
An exciting current may be supplied to the stator coil in an internal step pattern that is skipped one step in the front-rear direction from the final internal step. Furthermore, a second invention is a stator including a stator coil that generates a current magnetic field in an excited state, and a rotor including a rotor magnet that obtains a rotational force by electromagnetic interaction with the current magnetic field of the stator coil.
A sensorless multi-phase DC motor including: a counter electromotive voltage detection circuit for detecting an induced electromotive voltage of the stator coil; and first and second step steps of supplying an exciting current to the stator coil in a predetermined internal step pattern. In the starting method, the excitation pattern is controlled in accordance with the rotational position of the rotor based on the back electromotive voltage from the back electromotive voltage detection circuit between the first step and the second step. An accelerating step is provided, and the second stepwise step supplies the exciting current to the stator coil in an internal stepping pattern skipped two times in the front-rear direction from the final exciting pattern of the first accelerating step.

In the second invention, a current holding step for maintaining the final internal step of the first step is provided in place of the first acceleration step, and the second step of the second internal step is performed. An exciting current can be supplied to the stator coil in an internal step pattern skipped two steps in the front-rear direction from the step step. Further, in the first and second inventions, the first step step may have a reverse excitation drive operation in which the energization direction is reversed during the internal step step without including a rest period.

[0013]

In general, in a multi-phase DC motor, an internal step pattern for supplying an exciting current to each phase is determined in a step step. For example, in a three-phase DC motor, the exciting current is u →
Six steps of v, u → w, v → w, v → u, w → u, w → v are repeated. In the starting method of the first aspect of the invention having the above-described configuration, for example, if such an internal step pattern is adopted in the first step, the first step is changed to the first step.
Since the exciting current is supplied to the stator coil in an internal step pattern that is skipped by 1 in the front-back direction from the final excitation pattern of the first acceleration step that is performed immediately after the step step, for example,
Now, assuming that the final excitation pattern in the first acceleration step is w → u, the excitation current is supplied as u → v or v → w in the first step of the internal step pattern in the second step. By doing so, the reverse excitation drive operation is reliably performed in the initial stage of the second step process.

Further, in the starting method of the second invention, in the same manner as above, in the first step step, the exciting currents are u → v, u → w,
If an internal stepping pattern in which 6 steps of v → w, v → u, w → u, w → v are repeated is adopted, in the second stepping step, the first stepping step performed immediately after the first stepping step is performed. Since the exciting current is supplied to the stator coil in an internal step pattern skipped two times in the front-rear direction from the final excitation pattern of the first acceleration step, for example, if the final excitation pattern of the first acceleration step is w → u. In the first step of the internal step pattern of the second step process, if two skips are made, u → w and an exciting current are supplied. The reverse excitation drive operation is surely performed in the initial stage.

In this case, it should be particularly noted that the reverse excitation drive operation performed in the initial stage of the second step process is u and w.
, And the reverse excitation drive operation of these phases is negative to positive in the u phase and positive to negative in the w phase, which are opposite to each other. By performing the excitation drive operation, it is possible to shorten the start-up time of the motor.

Further, in the first and second inventions, the first
If a configuration is adopted in which the reverse excitation drive operation in which the energization direction is reversed without including the pause period is included during the internal step of the step step, the starting probability is further improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 1 to 4 show a first embodiment of a method for starting a sensorless polyphase DC motor according to the present invention. The starting method shown in the same figure is one in which the present invention is applied to a three-phase sensorless DC motor, and FIG. 1 shows the entire configuration including a control system of the motor. And a rotor (not shown) that obtains a rotational force by electromagnetic interaction with the magnetic field of the stator.

The stator has three-phase stator coils u,
The back electromotive force which detects the back electromotive force induced in each stator coil u, v, w during the rest time when the exciting current is not supplied to each stator coil u, v, w. The detection circuit 1 is connected. The control system of this embodiment includes a control unit 2 to which the detection signal of the back electromotive force detection circuit 1 is input, and a driver circuit 3 connected to the output side of the control unit 2.
And a control signal from the power circuit 4 and the control unit 2,
It has a sequencer 5 for outputting an output signal of a preset internal stepping pattern to the driver circuit 3 at the time of startup.

The power circuit 4 receives an output signal from the driver circuit 3 which operates based on a command from the control section 2, and supplies an exciting current in a pattern set for each stator coil u, v, w. The control unit 2 controls the start-up of the motor and the steady operation after the start-up based on a signal from the back electromotive force detection circuit 1. FIG. 2 shows a control flow at the time of starting performed by the control unit 2, and FIG. 3 shows a time chart of the step process at the time of starting.

In the stepping process shown in FIG. 3, the first and second stepping processes and the first and second acceleration processes are set, and the stepping process is repeated twice. In each step, an internal step pattern in which nine internal step steps are performed is set. Further, in this embodiment, the internal step pattern of the first step is, as shown in FIG. 4, a cycle in which the exciting current is u → v in the stator coils u, v, w in synchronization with the inertia of the motor. , U → w, v →
w, v → u, w → u, w → v
It is set that 9 to 9 internal stepping steps from to are performed.

In the control flow shown in FIG. 2, when the control unit 2 receives the start signal and operates, first, the start excitation counter is set in step s1, and the first step step is executed in step s2. In the first step step executed in step s2, the sequencer 5 is operated based on the control signal of the control unit 2, the output signal thereof is input to the driver circuit 3, and first, through the power circuit 4, In one internal step step, the stator coil u is energized to the same v for a predetermined time, and in the next second internal step step, the stator coil u is energized to the same w step. The stator coil u,
v and w are excited.

Then, when the first stepping process up to nine internal stepping steps is carried out, the first stepping step is carried out in step s3.
The acceleration process is performed for a predetermined time. At this time, the mutual position of the rotor magnet and the stator coils u, v, w is detected by the detection signal of the counter electromotive voltage detection circuit 1 connected to each of the stator coils u, v, w, and the detected position is detected. Then, the excitation pattern is changed and operation control is performed.

In the subsequent step s4, 2 is added to the count value of the excitation counter indicating the final excitation pattern in the first acceleration step, and the second step step is executed in step s5. If 2 is added to the count value of the excitation counter in this way, the internal step pattern in the second step is, for example, the first step in step s2, in which the motor is completely activated. If not, the final step of the internal step is the ninth internal step, as shown in FIG. 4, in which the exciting current is supplied to the stator coils v → w. ing.

When 2 is added to the excitation counter in step s5 with respect to the final internal step, the first internal step in the second step is performed with the stator coil v.fwdarw.u as in the conventional case. Instead of being supplied with current
The step of internal stepping is executed from w → u in the skipped state. An internal step pattern of the second step is shown in FIG.

When the second step process is performed in such a state,
In the initial state, in the state shown in FIGS. 4 and 5, the reverse excitation drive operation in which the exciting current is reversed from negative to positive is executed without including the idle time in the stator coil w. Such a reverse excitation drive operation is obtained not only when the motor is not started at all, but also when the start is insufficient in this embodiment.

That is, although the motor is slightly started, its torque is insufficient, and even if only the oscillation is completed in the first step, in the first acceleration step, the rotor magnet and the stator coils u, v, and Since the relative positional relationship with w is obtained by the counter electromotive voltage detection circuit 1, if this is the internal stepping step immediately before the execution of the second stepping step, for example, the second stepping step is performed. Then, the internal stepping is executed from the step obtained by adding 2 to the internal stepping step, whereby the reverse excitation drive operation in which the exciting current is reversed from the negative to the positive is executed without including the pause time in the stator coil v. Will be done.

In order to obtain such a reverse excitation drive operation, not only means for adding 2 to the excitation counter but also
Even if 2 is subtracted from the count value of the excitation counter to skip 1 forward from the final internal step in the first step, the reverse excitation drive operation similar to the above is executed at the beginning of the second step. To be done. When the second step process is executed in step s5, the second acceleration process is executed in step s6, and then the constant speed process is executed in step s7.

When the process moves to the constant speed process and the condition is not abnormal, the condition is maintained, and when an error occurs in the constant speed process, and this is detected in step s8, the process returns to step s1 and starts again. The process of is executed. By the way, according to the starting method of the multi-phase DC motor as described above, when the starting fails in the first step process, the reverse excitation drive operation is surely performed in the initial stage of the second step process. The magnetic flux density variation width is generated, the dead point of starting is eliminated, and high torque is generated, so that the motor is reliably started.

6 and 7 show a second embodiment of the present invention. In FIG. 6, FIG. 6 shows the steps of the internal step pattern performed in the first step step, and FIG. 7 shows an example of the internal step pattern performed in the second step step. In this embodiment, the internal step pattern of the first step is u for stator coils u, v, w.
The steps of supplying the exciting currents of → v, v → w, w → u are repeated. That is, steps skipped one by one with respect to the internal stepping pattern shown in FIG. 4 are executed.

Therefore, in each step of the first step, the energizing time of the exciting current is set to be twice as long as the step shown in the first embodiment, and each stator coil u, In v and w, each internal stepping pattern includes at least one reverse excitation drive operation in which the exciting current is inverted from positive to negative or from negative to positive without including pause time.

The internal step pattern of the second step shown in FIG. 7 shows the case where the motor is not started at all in the first step. In the internal step pattern of the second step shown in the figure, the final internal step of the first step supplies the exciting current to the stator coils v → w, so one skip forward Stator coil w →
starting from the step of supplying an exciting current to u, and
In each step, as in the first embodiment, the exciting current is u → v, u → w, v in the stator coils u, v, w.
It is set to be repeated in the order of → w, v → u, w → u, w → v.

Even when such an internal stepping pattern is set, the reverse excitation drive operation in which the exciting current is reversed from negative to positive in the stator coil w at the initial stage of the second step without including the pause time. Is performed, the same operational effect as that of the first embodiment is obtained, and particularly, since the reverse excitation drive operation is included in the first step process, the reliability of the start is further improved.

Also in this second embodiment, the motor oscillates in the first step, causing a change in the relative positional relationship between the rotor magnet and the stator coil, and exciting the first acceleration step. If the pattern changes,
The internal stepwise step of the second stepwise step is performed in a state where one skip is made in the front-back direction from the final excitation pattern of the first acceleration step. Further, in the second embodiment, the internal step pattern of the second step step shown in FIG. 7 adopts the same pattern as the internal step pattern of the first step step shown in FIG. Is also possible.

8 and 9 show a third embodiment of the starting method of the sensorless multi-phase DC motor according to the present invention. The start-up method shown in the figure is the one in which the present invention is applied to a three-phase sensorless DC motor as in the first and second embodiments, and only the characteristic feature will be described below.
Also in the starting method of this embodiment, the motor control system is the same as that in FIG. 1, and the control flow at the time of starting executed by the control unit 2 has the following characteristics.

FIG. 8 shows a control procedure of the step process at the time of starting, which is performed in this embodiment. In the control flow shown in FIG. 8, when the control unit 2 receives the start signal and operates, first, the start excitation counter is set in step s1, and the first step process is executed in step s2.
In the first step step executed in step s2, the sequencer 5 is operated based on the control signal of the control unit 2,
The output signal is input to the driver circuit 3, and first, in the first internal stepping step, the stator coil u is energized to the same v for a predetermined time through the power circuit 4, and then the second
In the internal step step, the stator coils u are energized to the same step w, and thereafter, the stator coils u, v, w are sequentially excited in accordance with the internal step pattern shown in FIG. In addition,
The internal step pattern of this first step step is the same as that of the first embodiment.

Then, when the first stepping process up to nine internal stepping steps is carried out, the first stepping step is carried out at step s3.
The acceleration process is performed for a predetermined time. At this time, the mutual position of the rotor magnet and the stator coils u, v, w is detected by the detection signal of the counter electromotive voltage detection circuit 1 connected to each of the stator coils u, v, w, and the detected position is detected. Then, the excitation pattern is changed and operation control is performed.

In the subsequent step s4, 3 is added to the count value of the excitation counter indicating the final excitation pattern of the first acceleration step, and the second step step is executed in step s5. If 3 is added to the count value of the excitation counter in this way, the internal step pattern in the second step is, for example, the first step in step s2, in which the motor is completely activated. If not, the final step of the internal step is the ninth internal step, as shown in FIG. 9, in which the exciting current is supplied to the stator coils v → w. ing.

When 3 is added to the excitation counter in step s5 with respect to the final internal step, the first internal step in the second step is performed by exciting the stator coil v → u as in the conventional case. Instead of being supplied with current
This is executed from the step of internal stepping in which the exciting current is supplied to w → v in the two skipped state. An internal step pattern of such a second step is shown in FIG.

When the second step process is performed in such a state,
In the initial state, in the state shown in FIG. 9, the reverse excitation drive operation in which the exciting current is reversed from negative to positive is executed without including the idle time in the stator coil w. In this case, it should be particularly noted that the reverse excitation drive operation performed in the initial stage of the second step process is performed in the two phases u and w, and the reverse excitation drive operation of these phases is performed in the u phase. In the negative phase to the positive phase, and in the w phase, the positive phase to the negative phase, which are opposite to each other. By performing such reverse excitation drive operation, the starting characteristic of the motor can be improved.

This reverse excitation drive operation is obtained not only when the motor is not started at all, but also when the start is insufficient in this embodiment. That is, although the motor is slightly started, its torque is insufficient, and even if only the swinging is completed in the first step,
For example, if the internal step is just before the execution of the second step, the internal step from the step obtained by adding 3 to the internal step is executed in the second step, and The reverse excitation drive operation in which the excitation current reverses from negative to positive is executed without including the pause time in the stator coils u and w.

In order to obtain such a reverse excitation drive operation, not only means for adding 3 to the excitation counter but also
Even if 2 is skipped forward from the final internal step of the first step by subtracting 3 from the count value of the excitation counter, the reverse excitation drive operation similar to the above is executed at the beginning of the second step. To be done. When the second step process is executed in step s5, the second acceleration process is executed in step s6, and then the constant speed process is executed in step s7.

Then, the process proceeds to the constant speed process, and if there is no abnormality in the state, the state is maintained, and an abnormality occurs in the constant velocity process, and when this is detected in step s8,
The process returns to step s1 and the processing at startup is executed again. Now, according to the starting method of the multi-phase DC motor as described above,
When the start-up fails in the first step process, the reverse excitation drive operation is reliably performed in the initial stage of the second step, so that a large magnetic flux density change width occurs and the start-up dead point is eliminated. High torque is generated, and the motor is reliably started.

In the third embodiment described above, the internal stepping pattern in which the reverse excitation driving operation is not provided in the first stepping step is exemplified, but in the first stepping step, the reverse excitation is performed similarly to the second example. It is also possible to provide a drive operation. In addition, in the above-described embodiment, the case where the first acceleration step of changing the exciting current based on the output signal of the back electromotive voltage detection circuit 1 is provided after the first step step has been described as an example. It is also possible to omit steps.

When the first acceleration step is omitted, a current holding step for maintaining the state of the final internal step of the first step step is provided, and in the second step step, the first step step is performed. 1 or 2 in the front-back direction from the final internal step
If the power is supplied in the skipped state, the same effect as that of the above-described embodiment can be obtained.

[0045]

As described above in detail in the embodiments,
According to the method for starting the sensorless multi-phase DC motor according to the present invention, since the reverse excitation drive operation is reliably performed in the initial stage of the second step process, the starting probability of the motor becomes very high,
The probability of startup failure is almost zero.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram including a control system of a sensorless polyphase DC motor to which a starting method according to the present invention is applied.

FIG. 2 is a flowchart showing a first embodiment of a starting method according to the present invention.

FIG. 3 is an explanatory diagram of a stepping process performed by the flowchart shown in FIG.

4 is an explanatory diagram of an internal step pattern in the first step step shown in FIG.

5 is an explanatory diagram of an internal step pattern in the second step step shown in FIG.

FIG. 6 is an explanatory diagram of an internal step pattern of a first step process adopted in the second embodiment of the starting method according to the present invention.

FIG. 7 is an explanatory diagram of an internal step pattern of a second step process employed in the second embodiment.

FIG. 8 is a flowchart showing a third embodiment of the starting method according to the present invention.

9 is an explanatory diagram of a stepping process performed by the flowchart shown in FIG.

[Explanation of symbols]

 1 Back Electromotive Voltage Detection Circuit 2 Control Section 3 Driver Circuit 4 Power Circuit 5 Sequencer u, v, w Stator Coil

Claims (5)

[Claims] 1. A stator including a stator coil that generates a current magnetic field in an excited state, a rotor including a rotor magnet that obtains a rotational force by electromagnetic interaction with the current magnetic field of the stator coil, and induction of the stator coil. A method for starting a sensorless multi-phase DC motor, comprising: a counter electromotive voltage detection circuit for detecting an electromotive voltage; and first and second step steps of supplying an exciting current to the stator coil in a predetermined internal step pattern. Between the first step and the second step, there is provided a first acceleration step for controlling the excitation pattern according to the rotational position of the rotor based on the counter electromotive voltage from the counter electromotive voltage detection circuit. In the second step, an exciting current is supplied to the stator coil with an internal step pattern that is skipped by 1 in the front-rear direction from the final excitation pattern of the first acceleration step. Sensorless polyphase dc motor startup method comprising. 2. The method for starting a sensorless multi-phase DC motor according to claim 1, further comprising a current holding step for maintaining a final internal step of the first step instead of the first acceleration step. The method of starting a sensorless multi-phase DC motor according to claim 2, wherein the second step step supplies an exciting current to the stator coil in an internal step pattern that is skipped by 1 in the front-rear direction from the final internal step step. 3. A stator having a stator coil for generating a current magnetic field in an excited state, a rotor having a rotor magnet for obtaining a rotational force by electromagnetic interaction with the current magnetic field of the stator coil, and induction of the stator coil. A method for starting a sensorless multi-phase DC motor, comprising: a counter electromotive voltage detection circuit for detecting an electromotive voltage; and first and second step steps of supplying an exciting current to the stator coil in a predetermined internal step pattern. Between the first step and the second step, there is provided a first acceleration step for controlling the excitation pattern according to the rotational position of the rotor based on the counter electromotive voltage from the counter electromotive voltage detection circuit. In the second step, an exciting current is supplied to the stator coil with an internal step pattern skipped two times in the front-back direction from the final excitation pattern of the first acceleration step. Sensorless polyphase dc motor startup method comprising. 4. The method of starting a sensorless multi-phase DC motor according to claim 4, further comprising a current holding step for maintaining a final internal step of the first step instead of the first acceleration step. The method of starting a sensorless multi-phase DC motor according to claim 2, wherein the second stepwise step supplies an exciting current to the stator coil in an internal stepping pattern skipped two times in the front-back direction from the final internal stepping step. 5. The sensorless according to claim 1, wherein the first step step has a reverse excitation driving operation in which the energization direction is reversed during the internal step step without including a pause period. How to start a multi-phase DC motor.