JPH11275887A - Brushless dc motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the switching from operation controlled by others to a self-controlled operation without fail, regardless of the existence of the components of rotating pulsation. SOLUTION: At switching from others-controlled operation being performed by applying specified frequency of application voltage to the winding of an armature to self-controlled operation whose phase is controlled, based on the position detection signal, the phase differences between the actual phases obtained based on the position signal and the phases of application voltage are sampled for a period equivalent to the last one revolution of the motor (S1). Then, if it is in leading phase condition where the phase of the application voltage advances by a specified value or over, this controller decreases (S6) the duty ratio of the application voltage, and in addition if it is in a delay phase condition where the phase of the application voltage is delayed for a specified value or more from the actual phase, this increases (S10) the duty ratio of the application voltage, and when all of each phase difference signal detected for a specified period are contained in the specified phase difference range (S4), and when a part of each phase difference signal detected for a specified period is contained in the specified phase difference range and that the remainder of each phase difference signal advances is in a leading phase condition (S9), this the switching is performed (S11).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation mode switching type brushless DC for switching from other control operation to self-control operation.
The present invention relates to a motor control device.

[0002]

2. Description of the Related Art Conventionally, there has been known a brushless DC motor control device of an operation mode switching type for switching from other control operation to self-control operation. In this control device, the brushless D
A PWM voltage is applied to the armature of the C motor in a predetermined duty ratio range to form a rotating magnetic field, which is started (other braking operation).
Then, the rotational speed is increased, the armature voltage is detected, the rotor position is determined from the phase, a PWM voltage having a phase determined based on the rotor position is formed, and the PWM voltage is applied to the armature. To drive the motor (self-control operation). In self-sustaining operation, acceleration and deceleration of the rotor is performed by controlling the duty ratio of the PWM voltage.

In this operation mode switching type brushless DC motor control device, after starting, the commutation control is performed based on the phase of the induced armature voltage, so that a special load such as a set of a permanent magnet and a magnetic sensor is used. There is a feature that a brushless DC motor having a simple configuration can be realized without requiring a motor position detecting means. More specifically, in reverse braking operation, since the motor speed is low, the back electromotive force is small, so that a large current easily flows. As a result, after the detected armature current reaches a predetermined current value, Control to provide a current interruption period of
It is desirable to perform current control PWM. In general, the carrier (transport) frequency in the current control PWM is set to be relatively low because the current cutoff period needs to be set long to sufficiently cut off the large current.

On the other hand, in self-sustained operation, a desired rotational speed is obtained by increasing or decreasing the torque by duty ratio control (also referred to as rotational speed control PWM). However, since the motor rotational speed is high, a large current does not easily flow. As a result, the PWM carrier frequency is set relatively high avoiding the audio frequency band. However, in such an operation mode switching type brushless DC motor control device, the torque change during the transition from the other control operation to the self-control operation (commutation phase shift) is large, in other words, the duty ratio change of the PWM voltage. Is too small, a step-out or a stop occurs. However, if it is too large, current consumption and shock increase.

For this reason, Japanese Patent Application Laid-Open No.
Japanese Patent Publication No. 131091 discloses that the initial duty ratio of the PWM voltage in the self-control operation immediately after the shift from the other braking operation is determined based on the duty ratio of the immediately preceding other braking operation, and the phase of the PWM voltage and the The duty ratio is gradually reduced from the initial duty ratio until the phase difference between the phase and the position signal obtained from the slave voltage falls within a predetermined range. Has been proposed.

[0006]

However, most of the load torque driven by the brushless DC motor or the generated torque generated by the brushless DC motor has a fluctuation in a cycle shorter than the rotation cycle. Has a periodic rotational pulsation component (torque ripple). For example, such a rotational pulsation component is remarkable in driving a compressor or the like.

On the other hand, the driving mode disclosed in the above-mentioned publication is disclosed.
In the mode switching, the duty ratio of the PWM voltage is gradually reduced from a predetermined initial duty ratio related to the other braking operation duty ratio, thereby reducing the phase difference between the driving voltage phase and the actual phase. However, when the phase difference falls within a certain range, the mode is switched to the self-control operation. Was.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a brushless DC motor control device capable of reliably switching from another braking operation to a self-limiting operation despite the presence of a rotational pulsation component. It is a problem to be solved.

[0009]

According to a first aspect of the present invention, there is provided a brushless DC motor control device, wherein a drive voltage having a predetermined frequency is forcibly applied to an armature winding, and a control operation is performed based on a position detection signal. At the time of switching to the self-limiting operation in which the phase number is controlled to control the rotation speed, a large number of phase differences between the actual phase obtained based on the position signal and the phase of the drive voltage are sampled in a predetermined period, and these many are sampled. Switching from other control operation to self-control operation is performed based on the phase difference signal.

That is, according to the present configuration, not a single piece of phase difference data detected at a predetermined time, but a large number of phase difference data sampled (detected) for a large number of continuous measurement periods are comprehensively determined. Then, it is determined whether it is possible to switch from the other control operation to the self-control operation. Therefore, compared to the case where the switching is performed only by the phase difference at the time of one detection as in the related art, it is better to prevent the occurrence of step-out due to insufficient torque generated immediately after the switching due to the influence of the rotational pulsation component. Can be.

[0011] The remote control operation can be performed by applying a PWM (pulse width modulation) voltage or a PAM (pulse amplitude modulation) voltage to the armature winding. According to a second aspect of the present invention, in the brushless DC motor control device according to the first aspect, the other control means or the self-control operation means applies a PWM (pulse width modulation) voltage as a drive voltage to the armature winding. Since the configuration is adopted, the configuration is simplified because the commutating semiconductor switching element can be used for PWM as compared with the configuration in which a PAM (pulse amplitude modulation) voltage is applied to the armature winding. Benefits arise.

According to a third aspect of the present invention, the brushless DC motor controller according to the first or second aspect further comprises:
Since it has the voltage detecting means for detecting the voltage of the armature winding during the other braking operation, it is possible to set the voltage applied to the armature winding at the initial stage of the operation mode switching to a value at the time of the completion of the other braking operation, Advantageously, overcurrent and overvoltage can be avoided, and the operation mode switching time can be reduced.

According to a fourth aspect of the present invention, in the brushless DC motor controller according to any one of the first to third aspects, a plurality of positions sampled over a period corresponding to one rotation immediately before the motor is further provided. The switching is performed based on the phase difference signal. With this configuration, the step-out due to the influence of the rotational pulsation component can be further avoided.

According to a fifth aspect of the present invention, in the brushless DC motor control device according to any one of the second to fourth aspects, further, when switching from another braking operation to the actual phase,
If the driving voltage phase is a leading phase state that is more than a predetermined value ahead of the actual phase, the duty ratio of the PWM voltage is reduced, and
If the driving voltage phase is delayed by more than a predetermined value from the actual phase, the duty ratio of the PWM voltage is increased to bring the driving voltage phase closer to the actual phase. In addition, it is possible to better suppress the situation.

According to a sixth aspect of the present invention, in the brushless DC motor controller according to any one of the first to fifth aspects, all of the phase difference signals detected over a predetermined period are included in a predetermined phase difference range. In such a case, the switching is performed, so that the step-out due to the influence of the rotational pulsation component can be reliably suppressed. According to the configuration described in claim 7, claim 1 is provided.
5. In the brushless DC motor control device according to any one of the above items 5, further, a part of each phase difference signal detected over a predetermined period is included in a predetermined phase difference range, and the rest of each phase difference signal is in a leading phase state. The switching is performed in some cases.

With this arrangement, at least in the past one rotation cycle, the lag phase, that is, the generated torque is smaller than the load torque, and the torque is insufficient, and all the phase difference signals are not in the advanced phase. Since there is no excessive generated torque, step-out due to insufficient torque can be reliably prevented, and switching shock due to excessive generated torque does not occur.

According to an eighth aspect of the present invention, in the brushless DC motor controller according to any of the second to fifth aspects, the PWM voltage is further detected for a predetermined period immediately after the duty ratio of the PWM voltage is increased by a predetermined amount. Switching is performed when all of the plurality of phase difference signals are in the advanced phase state. That is, the reason why the duty ratio of the PWM voltage is increased by a predetermined amount is that the generated torque is short before that. Even if the duty ratio is increased by a predetermined amount thereafter, the generated torque is not increased. It is certain that excesses have not occurred too much, so that switching can be performed while preventing step-out and shock.

According to a ninth aspect of the present invention, in the brushless DC motor control device according to any one of the first to fifth aspects, a part of the plurality of phase difference signals detected over a predetermined period is in a delayed phase state. In this case, no switching is performed, so that step-out due to insufficient generated torque can be reliably prevented. According to the tenth aspect of the invention, the phase control is performed based on the position detection signal, and the rotational speed is controlled by the duty ratio control, from the passive operation performed at the predetermined frequency and the PWM voltage having the predetermined duty ratio. Upon switching to operation, a phase difference between an actual phase obtained based on the position signal and a drive voltage phase that is a phase of the PWM voltage is detected.
The duty ratio of the PWM voltage is reduced if the drive voltage phase is more than a predetermined value from the actual phase, and PWM if the drive voltage phase is more than a predetermined value behind the actual phase.
Since the duty ratio of the voltage is increased, the drive voltage phase can be made to match the actual phase satisfactorily irrespective of the fluctuation of the actual phase, and the step-out and the shock at the time of switching the operation mode can be suppressed well. be able to.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment, it is preferable to gradually reduce the phase difference from the advanced phase state when switching from the other braking operation to the actual phase. This makes it possible to produce an effect that the motor is less likely to fall into the lag phase state. The preferred embodiments of the present invention will be described with reference to the following examples.

[0020]

(Construction) Sensorless brush D of this embodiment
The configuration of the C motor control device will be described with reference to FIG. 1
Is a brushless DC motor, 2 is a three-phase full-wave module (inverter circuit) composed of semiconductor switching elements for supplying power to the motor 1, 3 is a current sensor for detecting a current supplied to the motor 1, and 4 is a motor. A position detection circuit for detecting the position of the motor rotor from the terminal voltage; 5 a motor current control circuit for outputting a control signal 5a consisting of a pulse of a fixed width when the output of the current sensor 3 exceeds a specified value;
6 is obtained from the control signal 5a of the motor current control circuit 5 by its DU.
A DUTY detection circuit for detecting TY, 7 is a three-phase upper arm signal 8u, 8v, 8w, and a control signal 8 for a rotation speed control PWM.
a, control signal 5a and these two control signals 5a, 8a
From the switching signal 8b for switching the three-phase full-wave module 2
, A drive signal generation circuit for generating the upper arm drive signals 7w, 7v, 7u, 8 a microcomputer, and 9 a DC power supply.

Based on the position detection signals 4u, 4v, 4w output from the position detection circuit 4 and the DUTY signal output from the DUTY detection circuit 6, the microcomputer 8 performs three-phase upper arm signals 8u, 8v, 8w, 3 Phase lower arm signal 8x, 8
y, 8z, a control signal 8a, and a switching signal 8b are created.
The brushless DC motor 1 is a motor for driving a compressor of an air conditioner (not shown) mounted on an electric vehicle (not shown), and has a Y-connected armature winding (not shown). .

The three-phase full-wave module 2 includes IGBTs 21, 22, 2,
3 and I, each emitter being connected to the lower terminal of a DC power supply 9
It comprises GBTs 24, 25 and 26 and a feedback diode D connected between the emitter and collector of each IGBT. The emitters of the IGBTs 21 to 23 forming the upper arm are individually connected to the collectors of the IGBTs 24 to 26 forming the lower arm, and their connection points 27, 28 and 29 are connected to the terminals of the armature winding of the motor 1. ing.

The current sensor 3 detects a motor supply current flowing between each emitter of the IGBTs 24 to 26 and the lower terminal of the DC power supply 9. The position detector 4 includes three sets of filter circuits (not shown) for extracting a low-pass component of a three-phase voltage (PWM voltage) applied from the three-phase full-wave module 2 to the motor 1, and outputs these low-pass components. It is constituted by three sets of comparators (not shown) which convert the signals into pulse signals and send them to the microcomputer 8 as position detection signals 4u, 4v, 4w.

When the motor current detected by the current sensor 3 exceeds a predetermined limit value, the motor current control circuit 5 sends a control signal 5a consisting of a pulse of a fixed width to the duty detection circuit 6 and the drive signal generation circuit 7. I do. DUTY
The detection circuit 6 detects a duty from the control signal 5 a output from the motor current control circuit 5 and outputs the duty to the microcomputer 8.

As shown in FIG. 2, the drive signal generation circuit 7
It comprises AND gates 71-73 and a changeover switch 74. The changeover switch 74 switches between control signals 8a and 5a by a changeover signal 8b.
When the control signal 8a or the control signal 5a input from the changeover switch 74 is at a high level, the three-phase upper arm signals 8u, 8v, 8w output from the microcomputer 8 are converted into PWM signals.
As three-phase upper arm signals 7u, 7v, and 7w that form voltages,
Output to the three-phase full-wave module 2.

Thus, when the switching signal 8b is at a certain level (during another braking operation), the duty ratio of the PWM voltage output from the three-phase full-wave module 2 is controlled by the control signal 5a.
When the switching signal 8b is at another level (during self-limiting operation), the duty ratio of the PWM voltage output from the three-phase full-wave module 2 is determined by the control signal 8a.

The microcomputer 8 forms the three-phase upper arm signals 8u, 8v, 8w and the three-phase lower arm signals 8x, 8y, 8z from the synchronizing signal and outputs the same during the other braking operation (see FIG. 3). At this time, in order to limit the motor currents Iu, Iv, Iw, the drive signal generation circuit 7 uses the pulse 5a output from the motor current control circuit 5 to output the three-phase upper arm signals 8u, 8u.
Pulse width modulation is applied to the signals v and 8w (current control PWM), and the three-phase upper arm signals 7u, 7v and 7w having the waveforms shown in FIG. 5 are output. Also, during self-control, the microcomputer 8 outputs the three-phase upper arm signals 8u, 8v, 8w and the three-phase lower arm signals 8x, 8
y, 8z are generated based on the position detection signals 4u, 4v, 4w (see FIG. 6). (Operation) The operation of the brushless DC motor control device configured as described above will be described.

First, in the other braking operation, the three-phase upper arm signals 8u, 8v, 8w and the three-phase lower arm signals 8x, 8 shown in FIG.
The commutation signals 8u to 8z consisting of y and 8z are output to increase the rotation speed of the motor 1 as shown in FIG. t0 is the start time of the start, and t 'indicates the time when the rotation speed reaches a predetermined saturation value A. In order to keep the motor current constant,
The drive signal generation circuit 7 uses the control signal 5a to multiply the three-phase upper arm signals 8u, 8v, and 8w by PWM to obtain the current control P
Execute WM to regulate the motor current to a certain value or less. FIG. 5 shows the timing of each signal at this time. When the rotational speed of the motor reaches the saturation value A by the other braking operation, the acceleration by the other braking operation ends, and the frequency of the signals 8u to 8z becomes constant.

At the same time, the switching signal 8b switches,
The signals 8u to 8w are now modulated by the rotation speed control PWM by the control signal 8a. At this time, the DUTY (duty) of the control signal 8a is set so that the PWM voltage is equal to or slightly larger than that at the end of the acceleration in the other braking operation.
Ratio). DUTY of the control signal 8a (hereinafter, DUTY)
DUTY 8a) is obtained from the DUTY (hereinafter, also referred to as DUTY 5a) of the control signal 5a obtained from the DUTY detection circuit 6, the PWM carrier frequency of the control signal 5a known in advance, and the PWM carrier frequency of the control signal 8a. For example, it is calculated by the following formula. DUTY8a = DUTY5a + td × (f5a−f8
a) + Z Here, td is the operation delay time of the IGBTs 21 to 26, f5a is the PWM carrier frequency of the control signal 5a, f8a is the PWM carrier frequency of the control signal 8a, and Z is a predetermined value. Z is set to 0 when the PWM voltage is equal to that at the end of acceleration in the other braking operation, and Z is set to a constant value when slightly increased.

Thereafter, the microcomputer 8 determines the phase (actual phase) of the position detection signals 4u to 4w output from the position detection circuit 4.
And the phases of the signals 8u to 8z (drive voltage phases) are compared to determine a phase difference. When Z is set to 0, if the driving voltage phase is behind the actual phase, the duty ratio of the PWM voltage is increased until the phase difference falls within a predetermined range, and the driving voltage phase leads the actual phase. In this case, the duty ratio of the PWM voltage is reduced until the phase difference falls within the predetermined range, and when the phase difference falls within the predetermined range, the operation is switched to the self-limiting operation.

When Z is set to a predetermined value, the duty ratio of the PWM voltage is set to Z so that the drive voltage phase is always ahead of the actual phase, and then the duty ratio of the control signal 8a is changed. By gradually decreasing the phase of the PWM voltage, that is, the drive voltage phase, gradually approaches the actual phase, and when the phase difference falls within the predetermined range, the operation is switched to the self-limiting operation.

The switching operation from the other braking operation to the self-limiting operation will be described with reference to a timing chart shown in FIG. At time t2, the changeover switch 74 is switched by the changeover signal 8b, and the current control PWM by the control signal 8a is shifted to the rotation speed control PWM by the control signal 8a.

The time α1 is the time point t2 (the drive voltage phase at which the signal 8y changes from Hi to Lo and the signal 8z changes from Lo to Hi).
Indicates a delay time until the position detection signal (actual phase) 4u in the high level state changes to the low level, that is, a leading phase state difference. Time α2 is at time t3 (signal 8u is Hi
From the drive voltage phase at which the signal 8v changes from Lo to Hi) to the low-level position detection signal (actual phase) 4w
Indicates a delay time until the signal changes to a high level, that is, a leading phase difference.

The time α3 is the time point t4 (the drive voltage phase at which the signal 8x changes from Lo to Hi and the signal 8z changes from Hi to Lo).
Indicates a delay time until the position detection signal (actual phase) 4v in the high level state changes to the low level, that is, a leading phase difference. The time α4 is a delay time from the time point t5 (the drive voltage phase in which the signal 8v changes from Hi to Lo and the signal 8w changes from Lo to Hi) until the low-level position detection signal 4u changes to the high level, that is, the advance phase difference Is shown.

The time α5 is a time point t6 after the position detection signal (actual phase) 4w in the high level state changes to the low level.
(Drive voltage phase when signal 8x changes from Hi to Lo and signal 8y changes from Lo to Hi), that is, a delay phase difference. At time α6, the time t7 (the signal 8w changes from Hi to Lo, and the signal 8u changes from Lo to H) after the position detection signal (actual phase) 4v in the high level state changes to the high level.
(i.e., drive voltage phase i), that is, a delay phase difference.

Signals 8u, 8v, 8w, 8x, 8y, 8z
And the phase difference (phase angle) between the position detection signals 4u, 4v, and 4w are calculated by the following equation based on the delay times α1 to α6 (collectively αi). Where N is the number of revolutions, p
Is the number of motor pole pairs. 360: phase angle = 60 ° (N × p): αi phase angle = 360 × α × N × p ÷ 60 = 6 × α × N × p In this embodiment, time elapses from the elapsed time t2 (t
2, t3, t4 to t5) according to the control signal 8
a is gradually reduced, and the signals 8u, 8v, 8
w, 8x, 8y, 8z and position detection signals 4u, 4v, 4
The phase difference (phase angle) with w decreases.

Hereinafter, the leading phase difference such as the delay time α1 to α4 is “+”, and the lagging phase difference such as α5 and α6 is “−”.
Is defined. Further, the phase difference is divided into three stages, and each stage is defined as follows. A: 10 ° <phase difference B: 0 ° ≦ phase difference ≦ 10 ° C: phase difference <0 ° That is, A indicates an advanced phase state in which the phase difference exceeds 10 ° in electrical angle, and B indicates a phase difference of 0. Indicates a leading phase state of not less than 10 ° and less than 10 °, and C indicates a lagging phase state. Incidentally, in this embodiment, each measurement period T between t1 and t7 is an electrical angle of 60 °.

FIG. 7 shows the contents stored in the storage device (shift register) M built in the microcomputer 8 at times t5, t6, and t7. Signals 8u, 8v, 8w, 8x, 8
Each time a phase difference (phase angle) between y, 8z and the position detection signals 4u, 4v, 4w is detected, it is determined which of the above A, B, and C the detected phase difference corresponds to, and the storage device M In order. That is, 8u ~
Each time the logical state of 8z changes (at the timing of t1 to t7), one of the above A, B, and C is stored.

In this embodiment, since the number of pole pairs of the motor 1 is two, if the logic state of 8u-8z changes six times, the motor will rotate once. The control operation by the microcomputer 1 after the end of the remote control operation will be described with reference to FIG. First, in S1, it is determined whether or not it is time to determine the phase difference. When "Y" is obtained in S1, 1 is added to the variable N in S2. This variable N is for performing the phase difference determination for each rotation of the motor 1. Next, S3
It is determined whether the motor has made one rotation (N is 6 or more) from the previous phase difference determination. In S3, "Y"
Then, the process proceeds to the phase difference determination in S4. In S4, it is determined whether the contents of the storage device M are all “A”, and
If so, the process proceeds to S5, and if all are not “A”, the process proceeds to S9.

In S5, it is determined whether or not the contents of the storage device M 'in the previous phase difference state include "C". That is, the storage device M includes six phase difference data in the immediately preceding rotation, and the storage device M ′ further includes six phase difference data in the immediately preceding rotation. If there is no “C” in the storage device M ′, it is determined that the duty is excessive,
In step S6, the duty ratio is reduced by one step. In this embodiment, the duty ratio of the PWM voltage is divided into 64 steps.

In the next S7, the variable N is cleared to 0 so that the phase difference determination is not performed until the next rotation of the motor. In the next S8, the contents of the storage device M at this time are stored in another storage device M. And returns to S1 to continue the phase difference determination. If "C" is included in the storage device M 'in S5, it is determined that the phase difference has jumped over "B", and the operation shifts to self-limiting operation (S11).

Next, if all the contents of the storage device M are not "A" in S4, it is determined whether or not "C" exists in the storage device M in S9. If there is no "C", the contents of M include only "A" and "B", so that the operation shifts to self-limiting operation. If there is at least one "C" in the storage device M in S9, it is determined that the duty is insufficient, and the duty ratio is increased by one step in S10.
In step 7, the variable N is cleared to 0, so that the phase difference determination is not performed until the next rotation of the motor. In step S8, the content of the storage device M is stored in the storage device M ', and the process returns to step S1 to determine the phase difference. continue.

Patterns 1 and 2 in FIG. 9 show changes in the contents of the storage device M that have changed for each rotation by the above control. When shifting to the self-control operation, signals 8u to 8
Although the phase relationship between z and the position detection signals 4u to 4w is as shown in FIG. 10, there is almost no change in the motor rotation speed, and it is possible to smoothly shift from the other braking operation to the self-limiting operation.

[Brief description of the drawings]

FIG. 1 is a block diagram of a brushless DC motor control device according to this embodiment.

FIG. 2 is a circuit diagram of a drive signal generation circuit 7.

FIG. 3 shows three-phase upper arm signals 8u and 8 during other braking operation.
v, 8w, and three-phase lower arm signals 8x, 8y, 8z.

FIG. 4 is a graph showing a relationship between an elapsed time and a motor rotation speed in another braking operation.

FIG. 5 is a voltage waveform diagram of each part in another braking operation.

FIG. 6 is a voltage waveform diagram of each part when shifting from other braking operation to self-limiting operation.

FIG. 7 is a storage state diagram showing transition of storage contents of a microcomputer 8;

FIG. 8 is a flowchart showing the operation of the microcomputer 8 after the other braking operation is completed.

FIG. 9 is a storage state transition diagram showing the transition of the contents of the storage device M that has changed for each rotation of the motor 1.

FIG. 10 shows a three-phase upper arm signal 8u during self-limiting operation,
FIG. 8 is a waveform diagram showing 8v, 8w, three-phase lower arm signals 8x, 8y, 8z, and position detection signals 4u, 4v, 4w.

[Explanation of symbols]

Reference Signs List 1 brushless DC motor 2 three-phase full-wave module (inverter circuit) 4 position detection circuit (position detection means) 6 duty ratio detection circuit (duty ratio detection means) 7 drive signal generation circuit (operation mode) Switching means) 8 Microcomputer (other control means, self-control operation means, phase difference detection means) 21 to 26 IGBT (semiconductor switch element)

Claims (10)

[Claims] 1. An inverter circuit having a plurality of semiconductor switch elements for energizing and interrupting a current to a multi-phase armature winding of a brushless DC motor, and a drive voltage having a predetermined frequency by controlling the inverter circuit. Is applied to the armature winding to drive the brushless DC motor to a predetermined rotation value, and a rotational position of the magnet rotor based on an armature voltage induced in the armature winding. Position detecting means for outputting a position signal; self-limiting operation means for driving the brushless DC motor by driving the inverter circuit based on the position signal; and the magnet rotor obtained based on the position signal. Phase difference detecting means for detecting a phase difference between the actual phase of the drive signal and the phase of the drive voltage applied to the armature winding, and outputting a phase difference signal related to the phase difference; And a driving mode switching means for switching from the control mode to the self-control operation. The brushless DC motor control device comprising: a driving mode switching means for switching the state of the plurality of phase difference signals sampled during a predetermined period. A brushless DC motor control device, wherein the switching is performed on the basis of: 2. The brushless DC motor control device according to claim 1, wherein said other control operation means or self-control operation means applies a PWM (pulse width modulation) voltage as said drive voltage to said armature winding. Characteristic brushless DC motor controller. 3. The brushless DC motor control device according to claim 1, further comprising voltage detection means for detecting a voltage of said armature winding during said braking operation. . 4. The brushless DC motor control device according to claim 1, wherein said operation mode switching means includes said plurality of phase differences sampled over one or more rotations immediately before said motor. A brushless DC motor control device, wherein the switching is performed based on a signal. 5. The brushless DC motor control device according to claim 2, wherein said operation mode switching means switches the phase of said drive voltage when switching from said remote control operation to said actual phase. If the phase is advanced by more than a predetermined value from the actual phase, the PWM
If the duty ratio of the voltage is reduced and the phase of the drive voltage is delayed by a predetermined value or more from the actual phase, the duty ratio of the PWM voltage is increased to increase the duty ratio of the drive voltage. A brushless DC motor control device, wherein a phase is brought close to the actual phase. 6. The brushless DC motor control device according to claim 1, wherein said operation mode switching means is configured to control all of said plurality of phase difference signals detected over said predetermined period to a predetermined position. The brushless DC motor control device, wherein the switching is performed when the brushless DC motor is included in the phase difference range. 7. The brushless DC motor control device according to claim 1, wherein said operation mode switching means includes means for controlling a part of said plurality of phase difference signals detected over said predetermined period to a predetermined value. The brushless DC motor control device, wherein the switching is performed when the phase difference is included in the phase difference range and the remaining phase difference signals are in the advanced phase state. 8. The brushless DC motor control device according to claim 2, wherein said operation mode switching means includes a predetermined period immediately after increasing a duty ratio of said PWM voltage by a predetermined amount. A brushless DC motor control device, wherein the switching is performed when all of the plurality of phase difference signals detected over the period are in the advanced phase state. 9. The brushless DC motor control device according to claim 1, wherein said operation mode switching means includes means for switching a part of said plurality of phase difference signals detected over said predetermined period to said delay. A brushless DC motor control device, wherein the switching is not performed in a phase state. 10. An inverter circuit having a plurality of semiconductor switch elements for intermittently supplying current to a multi-phase armature winding of a brushless DC motor, and a predetermined frequency and a predetermined duty under control of the inverter circuit. A second braking means for applying a PWM voltage having a duty ratio to the armature winding to drive the brushless DC motor to a predetermined rotation speed; and a duty ratio for detecting the duty ratio at the time of the other braking operation. Detecting means, position detecting means for outputting a position signal indicating the rotational position of the magnet rotor based on the armature voltage induced in the armature winding, and energizing phase of the inverter based on the position detection signal. Self-control operation means for controlling and applying a PWM voltage to the armature winding; detecting a phase difference between an actual phase of the magnet rotor obtained based on the position signal and a drive voltage phase, A brushless DC motor control device comprising: a phase difference detection unit that outputs a phase difference signal related to the difference; and an operation mode switching unit that switches from the self-control operation to the self-control operation. The mode switching means reduces the duty ratio of the PWM voltage if the drive voltage phase is advanced by a predetermined value or more from the actual phase when switching from the remote control operation to the actual phase, and If the drive voltage phase is delayed by a predetermined value or more from the actual phase, the duty ratio of the PWM voltage is increased to bring the drive voltage phase closer to the actual phase. Control device.