JP2001197766A - Control device of brushless dc motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the rotary speed of a motor at a low speed in a phase control system. SOLUTION: A timer means 18 is provided, a position detection signal is inputted from a position detection part 12 to the timer means 18, and clock is started by the timer means 18 according to the rise of the position detection signal with a certain phase for continuously clock a specific period corresponding to an electric angle of 60 deg. that is the electric angle of the position detection signal of each phase, and is the half of a phase difference of 120 deg. in terms of an electric angle. Then, by a phase control part 15, for example, two phase control pulses are generated while the timer means 8 clocks a specific period once, and four phase control pulses are generated in a period being equivalent to a phase of 120 deg. in terms of an electric angle of each phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a brushless DC
The present invention relates to a control device for a brushless DC motor that drives and controls a motor.

[0002]

2. Description of the Related Art A conventional phase control type control device for driving and controlling a three-phase brushless DC motor is configured as shown in FIG. 5, for example.

As shown in FIG. 5, a three-phase brushless DC motor 1 includes three-phase stator windings 1a, U, V, and W and a rotor 1b, and the position of the rotor 1b is a Hall element. Detected by the position detecting unit 2, three position detecting signals of U, V, and W are output from the position detecting unit 2 with phases shifted by 120 °.

[0006] From the position detection signal of the position detection unit 2, the speed detection unit 3 calculates the rotation speed of the motor 1 by calculation and outputs a speed detection signal. The set speed thus set is compared by the speed difference signal generator 4, and a speed difference signal corresponding to the difference between the detected speed and the set speed is generated by the speed difference signal generator 4.
Generated by

Further, a three-phase control pulse based on the speed difference signal of the speed difference signal generator 4 is generated by the phase controller 5.
The phase control pulse is generated in synchronization with each position detection signal of each phase of the position detection unit 2, and the phase control pulse is input to the motor drive unit 6 to control the drive of the motor 1.

When the position of the rotor 1b of the motor 1 is detected by the position detecting section 2, the position detecting section 2
U, V, W phase position detection signals Up, V as shown in FIG.
p and Wp are output, and the speed detector 3 detects the rotational speed of the motor 1 from the position detection signals Up, Vp and Wp, and the phase controller 5 detects a speed difference corresponding to the difference between the detected speed and the set speed. Based on the signal, as shown in FIG.
The phase control pulses Ua, Va, and Wa of the U, V, and W phases are generated in synchronization with the position detection signals Up, Vp, and Wp of each phase of the position detection unit 2, respectively.

At this time, for example, the U-phase position detection signal Up
As an example, as shown in FIG. 6, the phase of the position detection signal Up is inverted every 180 ° in electrical angle, and the phase difference of the position detection signal between adjacent phases is 120 °. The same applies to the remaining V-phase position detection signal Vp and W-phase position detection signal Wp.

The electric current flows through the U, V, and W phase stator windings 1a of the motor 1 only at the above-mentioned electrical angle.
期間, and specifically, for example, U
Taking the phase control pulse Ua of a phase as an example, as shown in FIG. 6, two phase control pulses Ua during a period corresponding to a phase of 120 ° in electrical angle, that is, a period corresponding to a phase of 60 ° in electrical angle A phase control pulse Ua is generated every time.

As shown in FIG. 6, when the first phase control pulse Ua is generated in synchronization with the rise of the U-phase position detection signal Up, the second negative phase control pulse Va of the V phase is generated. Is generated, whereby a current flows from the U-phase to the V-phase stator winding 1a. Subsequently, as shown in FIG. 6, when the second phase control pulse Ua is generated, the first negative phase control pulse Wa of the W phase is generated.
A current flows through the phase stator winding 1a.

By repeating the same operation,
A current flows through the U, V, and W-phase stator windings 1a, and the direction of current flow to the stator windings 1a of each phase is sequentially switched.
The magnetic poles of the stator rotate in one direction, and the rotational force of the rotor 1b is obtained.

[0011]

However, in the case of the above-described conventional phase control method, the position detection signals Up and V of each phase are used.
During a period corresponding to a phase of 120 ° in electrical angles of p and Wp,
Since only two phase control pulses Ua, Va, and Wa are generated for each phase, there is a problem that the rotation speed of the motor 1 is not stable when the motor 1 becomes slow.

Further, once the motor 1 is stopped, since the position detection signals Up, Vp, Wp are not output from the position detection section 2, the phase control section 5 controls the phase control pulses Ua, Vp.
Also, there is a problem that it is difficult to generate a and Wa, and it is difficult to restart the motor 1.

Therefore, the present invention aims to stabilize the motor rotation speed at low speed in the phase control method,
An object is to facilitate restarting after a motor stops.

[0014]

In order to solve the above-mentioned problems, the present invention provides a phase control unit, wherein the phase control unit performs the phase control in a predetermined period corresponding to a half of the phase difference of the position detection signal of each phase. It is characterized in that a plurality of pulses are generated.

According to such a configuration, for example, in the case of three phases, the predetermined period corresponding to half of the phase difference of the position detection signal of each phase is half of 120 ° in electrical angle.
A period corresponding to the phase of 0 ° is obtained, and a plurality of, ie, two or more phase control pulses are generated in the period corresponding to the phase of 60 °.

[0016] Therefore, the number of phase control pulses is increased as compared with the conventional case described above, so that the rotation speed of the motor can be stabilized even when the rotation speed of the motor becomes low.

The present invention further comprises timer means for operating in response to the output of the position detection signal of a certain phase to continuously count the predetermined time, and the phase control unit controls the time of the predetermined time by the timer means. It is characterized in that a plurality of the phase control pulses are generated during timing.

According to such a configuration, since a plurality of phase control pulses are generated by the phase control unit during the counting by the timer means, the predetermined period corresponding to a half of the phase difference between the position detection signals of each phase. Thus, a plurality of phase control pulses can be reliably generated.

Further, according to the present invention, the phase control section may control the phase control signal for a predetermined period shorter than a period from the output of the phase detection signal of one phase to the output of the position detection signal of the next phase. Generating a plurality of the phase control pulses of
Continue the generation of the phase control pulse of the phase by the phase control unit during a delay period from the stop of the generation of the phase control pulse of this phase to the output of the position detection signal of the next phase. Means is provided.

According to such a configuration, after a plurality of phase control pulses of a certain phase are generated over a predetermined period, the delay period until the position detection signal of the next phase is output is measured by the measuring means. The phase control pulse is continuously generated by the phase control unit.

Therefore, even if the motor is stopped once, the phase control pulse is continuously generated until the position detection signal of the next phase is output, so that the motor can be easily restarted.

Further, according to the present invention, the continuation means operates by stopping generation of the phase control pulse of the certain phase, and stops operating by outputting the position detection signal of the next phase, and measures the delay period. The phase control unit is characterized in that the generation of the phase control pulse of the certain phase is continued during the time counting by the continuation unit.

According to such a configuration, while the continuation means keeps measuring the time, the phase control pulse is continuously generated by the phase control section, so that the position detection signal of the next phase is output until the output of the next phase position detection signal. It is possible to continuously generate the phase control pulse.

[0024]

(First Embodiment) A first embodiment in which the present invention is applied to a three-phase brushless DC motor will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a block diagram of a first embodiment of a control device according to the present invention, and FIG. 2 is a timing chart for explaining the operation.

As shown in FIG. 1, the brushless DC motor 11 includes three-phase stator windings 11a of U, V, and W and a rotating part 11b, and is arranged in three phases shifted by 120 °. A position detecting unit 12 comprising a Hall element is provided.
The position b is detected, and three-phase position detection signals of U, V, and W are output from the position detection unit 2 with a phase shift of 120 °.

The rotational speed of the motor 11 is derived by calculation from the position detection signal of each phase of the position detection unit 12 by the speed detection unit 13, and a speed detection signal is output.
Further, the detected speed detected by the speed detecting unit 13 and a set speed preset by a setting operation unit (not shown) are compared by the speed difference signal generating unit 14, and the detected speed is compared with the detected speed by the speed difference signal generating unit 14. A speed difference signal corresponding to the set speed difference is generated.

The phase control unit 15 generates three-phase control pulses based on the speed difference signal of the speed difference signal generation unit 14 in synchronization with the position detection signals of the respective phases of the position detection unit 12. This phase control pulse is applied to the motor drive unit 1
6, and the drive of the motor 11 is controlled.

Further, a timer means 18 is provided, to which a position detection signal from the position detecting unit 12 is inputted, and a certain phase (any phase of U, V, W) may be provided.
In response to the rise of the position detection signal, the timer means 18 operates to start time measurement.
A predetermined period Ta corresponding to 60 ° in electrical angle which is half the phase difference of 0 ° is continuously measured.

At this time, since the phase difference between the position detection signals of each phase is 120 ° in electrical angle as described above, the rise of the position detection signal of each phase and the timing of the start of timing by the timer means 18 are synchronized. As long as the input of the position detection signal from the position detection unit 12 is not stopped, the timer means 18 keeps the predetermined period T
Repeat the timing of a.

The phase control unit 15 includes a timer unit 18
Generates two phase control pulses, for example, while measuring the predetermined period Ta once. Therefore, by the phase control unit 15,
Two phase control pulses are continuously generated every 60 ° at an electrical angle of a predetermined period Ta, and the total number of phase control pulses is equal to the phase of the electrical angle of 120 °, which is the phase difference between the position detection signals of each phase. Four phase control pulses are generated.

By the way, the position of the motor 1
When the position of the first rotor 11b is detected, the position detection unit 1
2, the U, V, and W phase position detection signals Up, Vp, and Wp as shown in FIG. 2 are output, and the speed detector 13 detects the rotational speed of the motor 11 from these position detection signals Up, Vp, and Wp. Then, based on the speed difference signal corresponding to the difference between the detected speed and the set speed, the phase control unit 15 controls the phase control pulses Ub, V of the U, V, and W phases as shown in FIG.
b and Wb are the position detection signals U of the respective phases of the position detection unit 12.
It is generated in synchronization with each of p, Vp, and Wp.

At this time, for example, the U-phase position detection signal Up
As an example, as shown in FIG. 2, the phase of the position detection signal Up is inverted every 180 degrees in electrical angle, and the phase difference of the position detection signals between adjacent phases is 120 degrees. The same applies to the remaining V-phase position detection signal Vp and W-phase position detection signal Wp. This is the same as in FIG.

The electric current flows through the U, V, and W phase stator windings 11a of the motor 11 only at the above-mentioned electrical angle.
This is a period corresponding to a phase of 20 °. Specifically, for example, in the case of a phase control pulse Ub of the U-phase, as shown in FIG. 6
The timer is repeated by the timer means 18 for each period corresponding to the phase of 0 °, and the phase
Two phase control pulses are successively generated for each 連 続.

As shown in FIG. 2, for example, the first and second signals are synchronized in synchronization with the rise of the U-phase position detection signal Up.
When the third phase control pulse Ub is generated, the third and fourth negative phase control pulses Vb of the V phase are generated, so that a current flows from the U phase to the V phase stator winding 11a. Flows. Subsequently, as shown in FIG. 2, when the third and fourth phase control pulses Ub are generated, the first and second negative phase control pulses Wb of the W phase are generated. A current flows from the U-phase to the W-phase stator winding 11a.

By repeating the same operation,
A current flows through the U, V, and W phase stator windings 11a, and the direction of current flow to the stator windings 11a of each phase is sequentially switched, and the magnetic poles of the stator rotate in one direction and rotate. The rotational force of the child 11b is obtained.

Therefore, according to the first embodiment, the provision of the timer means 18 allows the phase control unit 15 to operate as long as the timer means 18 continues to measure a predetermined period Ta corresponding to a phase of 60 ° in electrical angle. , 2 for each predetermined period Ta
It becomes possible to continuously generate the number of phase control pulses.

As a result, the number of phase control pulses generated by the phase control unit 15 can be increased, as compared with the conventional case shown in FIGS. Even so, the rotation speed of the motor 11 can be stabilized, and the reliability can be improved.

In the above-described first embodiment, the timer means 18 is provided, and the timer means 18 uses the electric angle, which is the phase difference between the position detection signals Up, Vp, and Wp of each phase, as one.
A predetermined period Ta corresponding to a phase of 60 °, which is half of 20 °, is continuously measured, and a plurality of phase control pulses are generated by the phase control unit 15 during the counting of the timer means 18. Needless to say, the present invention is not limited to the case where the operation of the timer means 18 measures the predetermined period Ta corresponding to the phase of 60 ° in electrical angle.

In short, according to the present invention, a plurality of (2) in a predetermined period Ta corresponding to a phase of 60 ° which is half of 120 ° in electrical angle which is a phase difference between the position detection signals Up, Vp and Wp of each phase.
Or more) phase control pulses can be generated,
Any configuration may be used.

Further, the phase control unit 15 sets a predetermined period Ta.
Needless to say, the number of phase control pulses to be generated is not limited to two as described above, and may be three or more.

(Second Embodiment) A second embodiment in which the present invention is applied to a three-phase brushless DC motor will be described with reference to FIGS. However, FIG. 3 is a block diagram of the first embodiment of the control device according to the present invention, and FIG. 4 is a timing chart for explaining the operation.

3, the same reference numerals as those in FIG. 1 denote the same or corresponding elements, and the difference from FIG. 1 is that the operation is performed by stopping the generation of a phase control pulse of a certain phase instead of the timer means 18 in FIG. A continuation means 20 comprising a timer for stopping the operation by outputting the position detection signal of the next phase and continuing to generate the phase control pulse of the phase control section 15 is provided. Is temporarily stopped, and a delay period Tc from when the next phase position detection signal is output is measured.
Is a phase control pulse of this phase for a certain period Tb shorter than a period corresponding to a phase of 120 ° in electrical angle from the output of the phase detection signal of a certain phase to the output of the position detection signal of the next phase. And a continuation means 2
The point is that the phase control unit 15 is restarted by the output of the continuation unit 20 while the delay time Tc is counted as 0, and the phase control pulse of the phase is continuously generated.

Incidentally, the motor 1 is detected by the position detecting section 12.
When the position of the first rotor 11b is detected, the position detection unit 1
2, the U, V, and W phase position detection signals Up, Vp, and Wp as shown in FIG. 4 are output, and the speed detector 13 detects the rotation speed of the motor 11 from these position detection signals Up, Vp, and Wp. Then, based on the speed difference signal corresponding to the difference between the detected speed and the set speed, the phase control unit 15 controls the phase control pulses Uc, V of the U, V, and W phases as shown in FIG.
c and Wc are the position detection signals U of the respective phases of the position detection unit 12.
It is generated in synchronization with each of p, Vp, and Wp.

At this time, for example, the U-phase position detection signal Up
As an example, as shown in FIG. 4, the phase of the position detection signal Up is inverted every 180 degrees in electrical angle, and the phase difference of the position detection signals between adjacent phases is 120 degrees. The same applies to the remaining V-phase position detection signal Vp and W-phase position detection signal Wp. This is the same as in the first embodiment (see FIG. 2).

The electric current flows through the U, V, and W phase stator windings 11a of the motor 11 only at the above-mentioned electrical angle.
This is a period corresponding to a phase of 20 °, specifically, for example, taking a phase control pulse Uc of the U phase as an example, shorter than a period corresponding to a phase of 120 ° in electrical angle as shown in FIG. During the fixed period Tb, a plurality (three in FIG. 4) of phase control pulses Uc are generated by the phase control unit 15, and thereafter, the generation of the phase control pulses Uc by the phase control unit 15 is temporarily stopped.

By the way, the continuation means 20 starts the operation by stopping the generation of the phase control pulse Uc by the phase control section 15, and the continuation means 20 causes the next V-phase position detection signal V
A delay time Tc until p is output is measured. Then, while the continuation unit 20 measures the delay time Tc, two phase control pulses Uc of the U phase are continuously generated by the phase control unit 15 as shown in FIG.

As shown in FIG. 4, when the first, second, and third phase control pulses Uc are generated in synchronization with, for example, the rise of the U-phase position detection signal Up, the V-phase 4 Following the fifth negative phase control pulse Vc, the fifth and sixth negative phase control pulses Vc are continuously generated by the operation of the continuation means 20, so that the U-phase to V-phase stator windings are thereby generated. A current flows through the line 11a.

Further, as shown in FIG. 4, when the fourth and fifth phase control pulses Uc are continuously generated by the operation of the continuation means 20 following the third phase control pulse Uc, the V In place of the negative phase control pulse Vc of the phase, the first to third negative phase control pulses Wc of the W phase are generated.
A current flows from the phase to the W-phase stator winding 11a.

By repeating the same operation,
A current flows through the U, V, and W phase stator windings 11a, and the direction of current flow to the stator windings 11a of each phase is sequentially switched, and the magnetic poles of the stator rotate in one direction and rotate. The rotational force of the child 11b is obtained.

Therefore, according to the second embodiment, by providing the continuation means 20, even if the generation of the phase control pulse of one phase is stopped once, the delay time until the position detection signal of the next phase is output is output. Tc is measured by the continuation unit 20, and while the continuation unit 20 measures the time, the phase control unit 15 continuously generates a phase control pulse of that phase.

Therefore, even if the motor 11 stops once,
The phase control pulse is continuously generated until the position detection signal of the next phase is output, so that the motor 11 can be easily restarted.

In the second embodiment described above, the continuation means 20 for measuring the delay time Tc until the position detection signal of the next phase is output is provided. Although the case where the phase control pulse of the phase is continuously generated during the measurement of Tc has been described, the present invention relates to a case where the delay period Tc is measured by the operation of the continuation unit 20. Of course, the present invention is not limited to this.

Further, in the above-described second embodiment, the phase control unit 15 generates three phase control pulses during a fixed period Tb shorter than a period corresponding to a phase of 120 ° in electrical angle. The case where two phase control pulses are generated in the delay period Tc following the above is described. However, the number of pulses in the fixed period Tb and the delay period Tc is not limited thereto, and two or more pulses are generated in the fixed period Tb. At least one phase control pulse may be generated by the phase control unit 15 during the period Tc.

The present invention is not limited to the above embodiments, and various changes other than those described above can be made without departing from the spirit of the present invention.

[0055]

As described above, according to the first aspect of the present invention, the phase control unit generates a plurality of phase control pulses in a predetermined period corresponding to half the phase difference between the position detection signals of each phase. Since it is generated, it is possible to increase the number of phase control pulses compared to the related art, and it is possible to stabilize the rotation speed of the motor even when the rotation speed of the motor becomes low, thereby providing excellent reliability. Motor control can be realized,
It is possible to provide a phaseless brushless DC motor having excellent performance.

According to the second aspect of the present invention, since a plurality of phase control pulses are generated by the phase control unit during the time counting by the timer means, half of the phase difference between the position detection signals of each phase is generated. , A plurality of phase control pulses can be reliably generated in a predetermined period corresponding to.

According to the third aspect of the present invention, after a plurality of phase control pulses of a certain phase are generated over a predetermined period, a delay period until the position detection signal of the next phase is output. Since the phase control pulse is continuously generated, even if the motor stops once, the phase control pulse can be continuously generated until the position detection signal of the next phase is output, so that the motor can be easily operated. Restarting is possible, and a phaseless brushless DC motor with excellent performance can be provided.

According to the fourth aspect of the present invention, the phase control unit continuously generates the phase control pulse while the continuation unit keeps measuring the time, so that the position detection signal of the next phase is output. In the meantime, the phase control pulse can be continuously generated.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of a control device according to the present invention.

FIG. 2 is a timing chart for explaining the operation of the first embodiment of the present invention.

FIG. 3 is a block diagram of a control device according to a second embodiment of the present invention;

FIG. 4 is a timing chart for explaining the operation of the second embodiment of the present invention.

FIG. 5 is a block diagram of a conventional example.

FIG. 6 is a timing chart for explaining the operation of the conventional example.

[Explanation of symbols]

 Reference Signs List 11 brushless DC motor 11b timer means 12 position detection unit 13 speed detection unit 14 speed difference signal generation unit 15 phase control unit 16 motor drive unit 18 timer unit 20 continuation unit

Claims (4)

[Claims] 1. A position detecting unit for detecting a position of a rotor of a brushless DC motor and outputting a polyphase position detection signal,
A speed detector for detecting a rotation speed of the brushless DC motor and outputting a speed detection signal; and a speed difference for generating a speed difference signal corresponding to a difference between the speed detected by the speed detector and a preset speed. A signal generation unit, a phase control unit that generates a multi-phase control pulse based on the speed difference signal in synchronization with the position detection signal, and a motor drive unit that drives the brushless DC motor by inputting the phase control pulse In the control device for a brushless DC motor, the phase control unit generates a plurality of the phase control pulses in a predetermined period corresponding to a half of a phase difference of the position detection signal of each phase. Control device for a brushless DC motor. 2. The apparatus according to claim 1, further comprising timer means for operating in response to the output of the position detection signal of a certain phase to continuously count the predetermined time, wherein the phase control unit controls the time during the time counting of the predetermined time by the timer means. 2. The control device for a brushless DC motor according to claim 1, wherein a plurality of phase control pulses are generated. 3. A position detector for detecting a position of a rotor of the brushless DC motor and outputting a multi-phase position detection signal;
A speed detector for detecting a rotation speed of the brushless DC motor and outputting a speed detection signal; and a speed difference for generating a speed difference signal corresponding to a difference between the speed detected by the speed detector and a preset speed. A signal generation unit, a phase control unit that generates a multi-phase control pulse based on the speed difference signal in synchronization with the position detection signal, and a motor drive unit that drives the brushless DC motor by inputting the phase control pulse In the control device for a brushless DC motor, the phase control unit includes a fixed period shorter than a period from the output of the phase detection signal of one phase to the output of the position detection signal of the next phase. A plurality of the phase control pulses of this phase are generated, the generation of the phase control pulse of this phase is temporarily stopped, and then the position detection signal of the next phase is output. A control device for a brushless DC motor, further comprising: a continuation unit for continuing the generation of the phase control pulse of the phase by the phase control unit during a delay period until the delay. 4. The phase control unit operates by stopping the generation of the phase control pulse of the certain phase, stopping the operation by outputting the position detection signal of the next phase, and measuring the delay period. 4. The control device for a brushless DC motor according to claim 3, wherein the generation of the phase control pulse of the certain phase is continued during the time counting by the continuation unit.