JP2000060177A - Speed controller for dc brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC brushless motor, the rotating speed of which can be controlled with high accuracy even when the motor is operated at a low speed without being affected from the uneven magnetization of a rotor magnet and the errors of the mounting positions of Hall elements. SOLUTION: A speed controller controls the rotating speed of a DC brushless motor 1, in such a way that a plurality of Hall elements 2-4 detect the rotational position of the motor 1, and frequency dividing circuits 5-7 obtain rotating speed signals which indicate the rotating speed of the motor 1. Then a reference clock generating circuit 12 generates a reference clock, in accordance with an aimed rotating speed, and error signal generating circuits 8-10 detect the discrepancy of the rotating speed by comparing the rotating speed signals with the reference signal and output error signals. In addition, a signal combining circuit 11 obtains a speed control signal by combining the error signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC brushless motor speed controller for maintaining a constant rotation speed of a DC brushless motor.

[0002]

2. Description of the Related Art A conventional DC brushless motor speed control device will be described. FIG. 7 is a circuit diagram showing a first conventional example of the speed control device of the DC brushless motor 1 of the related art. The DC brushless motor 1 is provided with Hall elements 2, 3, and 4 for detecting the position of the rotor magnet.
The output signals of the Hall elements 2, 3, and 4 are originally used to rotate the rotor by switching the direction of the exciting current flowing through the coils of each phase. At the same time, the output signals are used to control the speed of the motor. I also use it.

When speed control is performed using the rotor position detection signals obtained by the Hall elements 2, 3, and 4, there is an advantage that a frequency generator for detecting the rotation speed of the motor 1 and the like need not be provided. When the DC brushless motor 1 is a three-phase motor, the three Hall elements 2, 3, and 4 are arranged at positions shifted by 120 electrical degrees.

In order to control the speed, the Hall elements 2, 3,.
After the analog signal obtained in step 4 is shaped into a pulse waveform representing a magnetic pole, the signal is synthesized by an EXOR (exclusive OR) circuit 20. As a result, the speed control signal is output from the EXOR circuit 20. Since the cycle of the speed control signal becomes shorter as the rotation speed of the motor 1 increases, the speed control device of the DC brushless motor 1 performs the speed control so as to adapt to the state of the target rotation speed.

FIG. 8 is a circuit diagram of a second conventional example of the speed control device of the DC brushless motor 1. As shown in FIG. When the DC brushless motor 1 is a three-phase motor, the electrical angle is 120
The position of the rotor is detected by three Hall elements 2, 3, and 4 arranged at positions shifted by degrees, and the speed control device separates the rotor position detection signal obtained by one of the Hall elements 2. The frequency is divided by the frequency dividing circuit 21 and one pulse is output each time the rotor makes one rotation. This frequency dividing circuit 21
Is used as a speed control signal to control the speed of the motor 1.

[0006]

In the conventional first speed control device for the DC brushless motor 1 (FIG. 7), the speed control signal has a timing error due to an uneven magnetization of the rotor magnet and an error in the mounting position of the Hall element. Misalignment may occur. Therefore, there is a problem that the speed control cannot be performed with high accuracy because the detection accuracy is not so high.

On the other hand, in the second conventional speed control device for the DC brushless motor 1 (FIG. 8), the frequency of the rotor position detection signal obtained by one Hall element 2 is divided, and one pulse is generated for one rotation of the rotor. Since the signal is used as a signal, there is no influence from an uneven magnetization of the rotor magnet and an error in the mounting position of the Hall element. However, since one pulse is obtained in one rotation by the frequency dividing circuit 21, the frequency of the speed control signal decreases and the interval between pulses appearing in the speed control signal increases. When the rotation speed is controlled by the speed control signal, the pulse interval is widened, which may cause rotation unevenness and may not achieve smooth rotation. In particular, during low-speed operation, the pulse interval of the speed control signal is greatly widened, so that there is a problem that high-precision rotation control cannot be performed.

The present invention is not affected by uneven magnetization of the rotor magnet or an error in the mounting position of the Hall element.
It is an object of the present invention to provide a DC brushless motor capable of performing high-accuracy speed control even in low-speed operation.

[0009]

In order to achieve the above object, a first configuration of the present invention has a plurality of rotor position detection means for outputting a rotor position detection signal, and comprises a plurality of rotor position detection signals based on the rotor position detection signal. A speed control device for a DC brushless motor that keeps the rotation speed of the rotor constant by using a rotation speed signal generation circuit that generates one rotation speed signal per rotation for each of the rotor position detection signals; A reference signal generation circuit for generating a reference signal corresponding to the rotation speed to be input, and an error signal indicating a difference between the rotation speed of the rotor and the target rotation speed by inputting the rotation speed signals and the reference signal. An error signal generation circuit that outputs the error signal, and a circuit that outputs a plurality of error signals from the error signal generation circuit as a rotation speed control signal of the rotor. There.

According to such a configuration, the speed control device of the DC brushless motor detects the position of the rotor with the plurality of rotor position detecting means and obtains a rotor position detection signal. Then, from the rotor position detection signal, the rotor generates one rotation speed signal per rotation by a rotation speed signal generation circuit. The error signal generation circuit detects a deviation between the actual rotation speed of the rotor and a target rotation speed from the reference signal and the rotation speed signal obtained by the reference signal generation circuit, and outputs an error signal. Then, the plurality of error signals obtained in this way are synthesized, and the speed control device of the DC brushless motor outputs a rotation speed control signal. By driving the motor to reduce this error, the rotation speed of the rotor can be maintained at a constant rotation speed.

According to a second configuration of the present invention, in the first configuration, the plurality of rotor position detecting means are Hall sensors arranged at every 120 electrical degrees, and the error signal generating circuit is The number corresponding to each Hall sensor is provided. In this specification, a Hall sensor is intended to mean a Hall element or a Hall IC.

According to such a configuration, when the DC brushless motor is a three-phase motor, the position of the rotor is detected by the Hall sensors arranged at every 120 electrical degrees to detect the position of the rotor.
Drive the C brushless motor. The rotor position detection signal obtained by the Hall sensor provided for this drive is represented by D
The speed control device of the C brushless motor can be commonly used for speed control. Since the error signal generation circuits are provided in a number corresponding to each Hall sensor, each error signal generation circuit outputs an error signal by inputting a rotation speed signal once per rotation. Since the signals are composed of error signals for three phases, the signals have a cycle including three error signals per rotation.

In a third configuration of the present invention, N rotor position detecting means are provided for detecting the rotational speed of the rotor, and an error with respect to a reference signal is generated using the output of one of the detecting means. The error is divided into N equal parts, and the error is distributed at the timing related to each rotor position detecting means and output as a speed control signal.

According to such a configuration, the speed control device of the DC brushless motor uses the output of one of the detecting means to indicate the difference between the actual rotation speed and the reference signal generated according to the target rotation speed. Generate an error. Then, this error is divided into N equal parts and distributed at the timing obtained by the N rotor position detecting means to generate the speed control signal. Therefore, the speed control signal is larger than the error signal obtained by one rotor position detecting means. The cycle becomes shorter. By driving the DC brushless motor so as to reduce this error, the rotation speed of the rotor can be kept constant.

According to a fourth configuration of the present invention, in the third configuration, the first, second, and third Hall sensors provided as the N rotor position detecting means and arranged at every 120 electrical degrees. A frequency dividing circuit for dividing the output of the first Hall sensor to output one pulse per rotation of the rotor; a reference clock generating circuit; and a rotation of the rotor based on a reference clock and an output of the frequency dividing circuit. An error signal generation circuit that outputs an error pulse corresponding to a speed error signal; a pulse width adjustment circuit that outputs a speed control pulse obtained by converting the error pulse into a pulse having a width of 1/3; A first timing adjusting circuit for outputting the speed control pulse at a timing related to the second Hall sensor from an output of the second Hall sensor and the speed control pulse, and an output of the frequency dividing circuit A second timing adjustment circuit that outputs the speed control pulse at a timing related to the third Hall sensor from the output of the third Hall sensor and the speed control pulse, and the pulse width adjustment circuit, And a synthesizing circuit that outputs the output of the timing adjustment circuit as a speed control signal.

According to this configuration, when the DC brushless motor is a three-phase motor, the three Hall sensors provided for driving the motor are shared by the three Hall sensors for speed control. One pulse is output for one rotation by dividing the frequency of the signal representing the rotational position of the rotor by a frequency dividing circuit. Then, an error pulse is generated by the error signal generation circuit from the reference signal obtained by the reference clock generation circuit and the output of the frequency divider circuit. Then, the error pulse is converted into a pulse having a width of 1/3 by the pulse width adjusting circuit. Then, the first timing adjustment circuit outputs a speed control pulse obtained by the pulse width adjustment circuit at a timing related to the second Hall sensor. The third timing adjustment circuit
A speed control pulse obtained by the pulse width adjustment circuit is output at a timing related to the Hall sensor. Then, by combining the outputs of the pulse width adjustment circuit and the first and second timing adjustment circuits in the synthesis circuit, an error control signal having a cycle including three speed control pulses per rotation can be output.

In a fifth configuration of the present invention, a plurality of detecting means for detecting the magnetic pole of the rotor are provided, and an error with respect to a reference signal is output as a speed error signal using an output of one of the detecting means. At a timing relating to the detecting means, a predetermined acceleration signal is output, and the rotational speed of the rotor is controlled by the speed error signal and the acceleration signal.

According to such a configuration, the speed control device of the DC brushless motor detects the magnetic pole of the rotor by the detecting means. An error with respect to a reference signal provided corresponding to a target rotation speed is output as a speed error signal from the output of the detection means. In addition, an acceleration signal corresponding to a target rotation speed or the like is output at a timing related to another detection unit. By controlling the rotation speed of the rotor with a signal obtained by combining the speed error signal and the acceleration signal, the speed control device of the DC brushless motor can keep the rotation speed of the rotor constant. When the motor is started, the speed error signal becomes an acceleration signal, so that the speed of the motor is increased at a stretch together with a predetermined acceleration signal output at a timing related to other detection means, and the start is performed quickly. When the speed reaches a normal speed, the speed error signal becomes a deceleration signal, and the rotor is kept at a constant speed by an acceleration signal at a timing related to other detecting means.

In the sixth configuration of the present invention, the fifth configuration
And the first, second, and third Hall sensors provided as the plurality of detecting means and arranged at every 120 electrical degrees, and the output of the first Hall sensor is divided to make one rotation of the rotor. A frequency divider circuit for outputting one pulse per clock, a reference clock generation circuit, an error signal generation circuit for outputting an error pulse corresponding to a rotation speed error of the rotor from a reference clock and an output of the frequency divider circuit, Acceleration pulse generation means for generating an acceleration pulse; an output of the frequency dividing circuit; an output of a second Hall sensor; and a first timing adjustment for outputting the acceleration pulse at a timing related to the second Hall sensor from the acceleration pulse. Outputting the acceleration pulse at a timing related to the third Hall sensor from the circuit, the output of the frequency dividing circuit, the output of the third Hall sensor, and the acceleration pulse. A second timing adjusting circuit that outputs a first of said error signal generation circuit, so that consisting of combining circuit outputs the output of the second timing adjusting circuit as the speed control signal.

According to such a configuration, when the DC brushless motor is a three-phase motor, the three Hall sensors provided for driving the motor are shared by the three Hall sensors for speed control. One pulse is output per one rotation by dividing the frequency by a frequency dividing circuit from a signal indicating the rotational position of the rotor. Then, the error signal generation circuit generates an error pulse with respect to the reference clock signal obtained by the reference clock generation circuit from the output of the frequency dividing circuit. Also,
The first timing adjustment circuit outputs an acceleration pulse determined according to a target rotation speed or the like at a timing related to the second Hall sensor, and the second timing adjustment circuit outputs a predetermined acceleration pulse at a timing related to the third Hall sensor. Output acceleration pulse. Then, the combining circuit combines the output of the error signal generation circuit and the outputs of the first and second timing adjustment circuits and outputs the result as a speed control signal. Therefore, the output of the first Hall sensor is output as a speed error signal with respect to the reference signal, and the first and second timing adjustment circuits output predetermined acceleration pulses at timings related to the outputs of the second and third Hall sensors, The rotation speed of the rotor can be controlled by the error signal and the acceleration pulse.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> An embodiment of the present invention will be described below. FIG. 1 is a block diagram of a speed control device for a DC brushless motor 1 according to a first embodiment of the present invention. The DC brushless motor 1 is a three-phase motor, and a rotor rotates when a magnetic field is applied to a rotor magnet by a drive circuit (not shown). The Hall elements 2, 3, and 4 detect the position of the rotor by detecting the magnetic pole of the rotor magnet. Hall element 2,
The analog signals obtained from 3 and 4 are shaped to obtain a binary position rotor position detection signal indicating an N pole or an S pole. For example,
The rotor position detection signal has an N pole when it is at a high level and an S pole when it is at a low level. Then, a drive circuit (not shown) rotates the rotor by switching the direction of the coil current provided for each phase in accordance with the rotor position detection signals output from the Hall elements 2, 3, and 4.

On the other hand, the speed control device of the DC brushless motor 1 controls the rotation of the motor 1 by using the rotor position detection signals obtained by the three Hall elements 2, 3, and 4. The Hall elements 2, 3, and 4 are arranged at positions shifted by 120 electrical degrees. FIG. 2A shows a rotor position detection signal A output from the Hall element 2.

The frequency dividing circuit 5 divides the rotor position detection signal A to output a rotation speed signal B for outputting one pulse each time the rotor makes one revolution (see FIG. 2B). At the same time, the frequency dividing circuit 6 divides the rotor position detection signal indicating the magnetic pole obtained by the Hall element 3 to output a rotation speed signal for outputting one pulse each time the rotor makes one rotation. The frequency dividing circuit 7 divides the rotor position detection signal indicating the magnetic pole obtained by the Hall element 4 to output a rotation speed signal that outputs one pulse every time the rotor makes one rotation. By the frequency dividing circuits 5, 6, and 7, three-phase rotation speed signals are obtained.

The reference clock generation circuit 12 outputs a reference clock (reference signal) (see FIG. 2C) set according to the target rotation speed of the rotor of the motor 1. The error signal generation circuit 8 compares the rotation speed signal B output from the frequency dividing circuit 5 with the reference clock C, and indicates an error signal D (FIG. 2) indicating a difference between the rotation speed of the rotor and the target rotation speed.
(See (D)).

The error signal generating circuit 9 receives the rotation speed signal output from the frequency dividing circuit 6 and a reference clock and outputs an error signal. The error signal generating circuit 10 receives the rotation speed signal output from the frequency dividing circuit 7 and the reference clock and outputs an error signal. The signal combining circuit 11 combines the three error signals output from the error signal generating circuits 8, 9, and 10 to output a speed control signal E (see FIG. 2E). In addition,
The three reference clocks output from the reference clock generation circuit 12 are out of phase by 120 degrees.

FIG. 2 is a waveform chart showing the operation of the speed control device for the DC brushless motor 1 of the present embodiment. The rotor position detection signal A is obtained by shaping an analog signal obtained by the Hall element 2 into a pulse waveform, and indicates the rotation position of the rotor as an N pole when it is at a high level and as an S pole when it is at a low level. ing.

This signal A has a frequency of 1/6 in a frequency dividing circuit 5.
And is converted into a rotation speed signal B which outputs one pulse each time the rotor makes one rotation. FIG.
Then, the signal B rises at the rising timing t1 of the signal A, then falls at the third rising timing t3 of the signal A, and further falls at 3
The signal B rises at the timing t4 of the second rising of the signal A. Thereafter, the signal B is periodically repeated at this level switching timing.

The error signal generation circuit 8 compares the rotation speed signal B with the reference clock C. For example, at the timing t1 when the rotation speed signal B rises to the high level, the reference clock C remains at the high level, so that the error signal generation circuit 8 performs the rotation indicating the actual rotation state of the rotor with respect to the target rotation speed. It is determined that the phase of the speed signal B is advanced. At this time, the error signal generation circuit 8 outputs an error signal D having a predetermined positive voltage from the timing t1 to the next falling timing t2 of the reference clock C.

When the error signal D is a positive voltage, the speed control device controls a drive circuit (not shown) so that the motor 1 is decelerated. Conversely, control is performed so that the motor 1 is accelerated when the error signal D is a negative voltage. Further, a period T1 from the timing t1 to t2 indicates a phase shift between the rotation speed signal B and the reference clock C, and thus also indicates a deceleration amount.

Since the signal synthesizing circuit 11 synthesizes the error signals output from the error signal generating circuits 8, 9, and 10, a pulse 30 indicating the acceleration of the motor appears in the speed control signal E from timing t1 to t2. . Hall element 2,
3 and 4 are provided at positions where the electrical angle is shifted by 120 degrees. 31 appears. Thereafter, a pulse 32 due to the error signal obtained by the Hall element 4, the frequency divider 7 and the error signal generator 10 appears in the speed control signal E. Error signal 3
Since 2 has a negative voltage, acceleration control is performed.

Thereafter, in the error signal generating circuit 8, a period T2 from the rising timing t4 of the signal B to the falling timing t5 of the next reference clock C is set to a positive voltage. In the operation example shown in FIG. 2, since the period T2 is narrower than the period T1, it indicates that the deceleration amount is small. As a result, a pulse 33 for deceleration control appears in the signal E.

Thereafter, the signal B rises at a timing t7 after the timing t6 of the falling of the reference clock C. In the error signal generation circuit 8, the reference clock C
Can be determined that the phase of the rotation speed signal B is delayed. At this time, the error signal generation circuit 8 outputs an error signal with a predetermined negative voltage from timing t6 to t7. A negative voltage pulse 34 appears in the speed control signal E to accelerate the motor 1. Timing t6
A period T3 from to t7 indicates the amount to be decelerated.
Then, a pulse 35 due to the error signal obtained by the error signal generation circuit 9 appears.

As described above, in this embodiment, the rotor position detection signals obtained by the Hall elements 2, 3, and 4 are divided by the frequency dividing circuits 5, 6, and 7, respectively, so that one rotation of the rotor is performed. Since one pulse is used to generate the speed control signal E, the speed control signal E does not cause deterioration of the accuracy of the speed control signal E due to uneven magnetization of the rotor magnet in the motor 1. . , And 3
Since the speed control signal E is generated using the signals from the Hall elements 3, 4, and 5, the frequency of the signal E does not decrease. Therefore, even when the motor 1 is operated at a low speed, rotation unevenness is unlikely to occur.

In this embodiment, the frequency dividers 5, 6, 7
Outputs one pulse each time the rotor makes one rotation, but the speed control device of the DC brushless motor controls the speed by outputting one pulse every two or more rotations of the rotor. Is also possible. However, in such a case, the cycle of the speed control signal becomes large, so that it is impossible to perform highly accurate control. Therefore, it is the highest control accuracy to output one pulse per rotation. In addition, as shown in FIG.
0 to 35 occur at timings related to the Hall elements 2, 3, and 4, that is, at timings corresponding to known electrical angles of the Hall elements.

<Second Embodiment> Next, a second embodiment of the present invention will be described. FIG. 3 is a block diagram of a speed control device of the DC brushless motor 1 according to the second embodiment of the present invention. The DC brushless motor 1 is a three-phase motor in which three Hall elements 2, 3, and 4 are arranged at positions shifted by 120 electrical degrees. In FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals (however, alphabets do not always indicate the same parts), and detailed description thereof will be omitted. The Hall element 2 outputs a rotor position detection signal A (see FIG. 4A) indicating the rotation position of the rotor by detecting the magnetic pole of the rotor magnet. The frequency dividing circuit 5 divides the signal A to output a rotation speed signal B which outputs a pulse once each time the rotor makes one rotation.

The reference clock generating circuit 12 generates a reference clock (reference signal) C (FIG. 4) according to a target rotation speed.
(See (C)). The error signal generation circuit 8 outputs the signal B
And a reference clock C, and outputs an error signal D (see FIG. 4D). The pulse width adjusting circuit 15 outputs a signal F (see FIG. 4 (F)) in which the period during which the error signal D has a positive voltage or a negative voltage is reduced to ３. The output timing of the signal F is synchronized with the fall of the signal B as described later.

The Hall element 3 outputs a rotor position detection signal GP of the motor 1. The rotor position detection signal GP is a signal having the same period as the rotor position detection signal A shown in FIG. 4A, but the timing adjustment circuit 16 receives the signal B and receives the signal as shown by the dotted line in FIG. The timing corresponding to the rotation speed signal of one pulse in one rotation is captured. This can be realized, for example, by inputting the signal B to the data terminal of the D flip-flop and inputting a predetermined detection signal GP (a pulse two cycles later than the signal A) to the clock terminal. A signal I (see FIG. 4 (C)) in which the period T3 obtained by the signal F at the falling timing t5 of the signal G (see FIG. 4 (G)) formed by the fetched timing is a positive voltage.
Is output.

The Hall element 4 outputs a rotor position detection signal HP of the motor 1. The rotor position detection signal GP is a signal having the same cycle as the rotor position detection signal A, but the timing adjustment circuit 17 receives the signals B, F, and HP, and first receives signals B and HP from the signals B and HP as shown by the dotted line in FIG. The timing corresponding to one pulse in one rotation as shown by is taken in. Then, a signal J is output in which the period T3 obtained by the signal F is set to a positive voltage at the falling timing t8 of the signal H formed at that timing. The signal synthesizing circuit 11 generates the speed control signal K by synthesizing the signals F, I and J.

As shown in the signal waveform diagram of FIG. 4, in this embodiment, the error signal (positive pulse having a width of T1) formed at timing t1 to t2 is divided into three equal parts, and the Hall elements 2, 3, 4
And output at timings t4, t5, and t8 (timings relating to the electrical angle of each Hall element). Similarly, the error signal (positive pulse having a width of T4) formed at timings t6 to t7 is divided into three equal portions and output to timings t9, t10, and t13. Further, the error signal (negative pulse having a width of T6) formed at timings t11 to t12 is divided into three equal parts and output at a timing related to the position of the Hall element. The three (distributed) distributed signals are combined by the signal combining circuit 11 to output the speed control signal K. In this case, the speed control signal K
Is shortened similarly to the above-described first embodiment (FIG. 1), and highly accurate speed control can be performed.

<Third Embodiment> Next, a third embodiment of the present invention will be described. FIG. 5 is a block diagram of a speed control device of the DC brushless motor 1 according to the third embodiment of the present invention. In this embodiment, the same parts as those in the above-described second embodiment (FIG. 3) are denoted by the same reference numerals (however, alphabets do not always indicate the same parts), and description thereof will be omitted. The difference between the second embodiment (FIG. 3) and the present embodiment (FIG. 5) is that in the second embodiment (FIG. 3), a pulse width adjustment circuit is used to provide a pulse width to the timing adjustment circuits 16 and 17. Although 15 is provided, in this embodiment, an acceleration pulse generating circuit 18 is provided instead to give a pulse width to the timing adjusting circuits 16 and 17. The acceleration pulse generation circuit 18 outputs an acceleration pulse (acceleration signal) having a certain width according to a target rotation speed.

FIG. 6 is a waveform chart showing the operation of the speed control device for the DC brushless motor 1 of the present embodiment. The signal A is a rotor position detection signal A output from the Hall element 2. The rotation speed signal B is obtained by dividing the signal A by the frequency dividing circuit 5. The reference clock C is a reference signal output from the reference clock generation circuit 12 and having a certain width according to a target rotation speed. Reference clock C
Since the rotation speed signal B rises at the timing t2 after the falling timing t1, the error signal generation circuit 8 indicates that the rotor is behind the target rotation, and the error signal generation circuit 8 operates from the timing t1 to the timing t2. , An error signal D is output with the period T1 being a predetermined positive voltage. Since the signal D is synthesized by the signal synthesizing circuit 11, a positive voltage pulse 50 appears in the speed control signal I, and the speed control device performs acceleration control.

The Hall element 3 outputs a rotor position detection signal EP. This rotor position detection signal EP is a signal whose cycle matches that of the rotor position detection signal A. The timing adjustment circuit 16 captures the timing corresponding to one pulse (signal E) in one rotation as shown by the dotted line by the input of the detection signal GP and the signal B. Then, for example, at the timing t3 of the rise of the signal E (see FIG. 4E), the control signal G is output with the width T2 of the acceleration pulse obtained from the acceleration pulse generation circuit 18 as a positive voltage. As a result, a pulse 51 appears in the speed control signal I.

The Hall element 4 outputs a rotor position detection signal FP. This rotor position detection signal FP is a signal whose cycle matches that of the rotor position detection signal A. The timing adjustment circuit 17 captures the timing corresponding to one pulse (signal F) in one rotation as shown by the dotted line by the input of the detection signal FP and the signal B. Then, for example, at the timing t6 of the rise of the signal F (see FIG. 4F), the control signal H is output with the width T2 of the acceleration pulse obtained from the acceleration pulse generation circuit 18 as a positive voltage. As a result, the pulse 52 appears in the speed control signal I.

Thereafter, at timing t8 when the rotation speed signal B rises, the reference clock C is at the high level, which indicates that the rotor is ahead of the target rotation. The error signal generation circuit 8 outputs a negative voltage during a period T3 from the timing t8 to the timing t9 from the fall of the next reference clock C to decelerate the rotor. As a result, a negative voltage pulse 53 appears in the rotation speed signal I. Then, the timing adjustment circuit 16 outputs a positive voltage to the pulse width T2 given by the acceleration pulse generation circuit 18 at the timing t10 given by the signal E. The timing adjustment circuit 17 outputs the signal H in the period T2 as a positive voltage at the timing t13 given by the signal F. As a result, a pulse 55 appears in the rotation control signal I.

The error signal generation circuit 8 outputs the next rotation speed signal B
From the rising timing t15 to the falling timing t16 of the reference clock C, the error signal D is output. As a result, a pulse 56 for instructing deceleration appears in the speed control signal I. FIG.
As shown in I, the pulses 50 to 56 are applied to each Hall element 2,
It occurs at timings related to electrical angles of 3 and 4.

As described above, in the speed control device for the DC brushless motor 1 of the present embodiment, when the motor 1 is started, the rotation control signal I is given a constant acceleration by the acceleration pulse output from the acceleration pulse generation circuit 18. Since the control signal is given, the motor 1 is accelerated until it reaches the target rotational speed. When the rotation speed exceeds the target rotation speed, the error signal generation circuit 8 outputs an error signal D for instructing deceleration of the rotor, so that the rotor is decelerated and accelerated by the acceleration signals G and H. By repeating this, the rotation speed of the rotor can be maintained at the target rotation speed. In other words, in this embodiment, the acceleration is controlled by the acceleration signals G and H, and is accelerated by the error signal (particularly at the time of startup) or decelerated, so that the rotation speed is kept constant.

[0047]

As described above, according to the DC brushless motor speed control apparatus of the first aspect, the rotor position detection signal obtained by the rotor position detection means obtained by the rotor position detection means is reduced to one rotation. The signal is output from the reference signal generation circuit as one rotation speed signal. Since the error signal generating circuit outputs the error signal after comparing with the reference signal, the error signal is not distorted due to the uneven magnetization of the rotor magnet or the displacement of the mounting position of the Hall sensor. Therefore, high-precision speed control can be performed. Further, since a plurality of error signals are combined to form a rotation speed control signal, the cycle of the rotation speed control signal is shorter than the cycle of one error signal. Therefore, since the speed control is performed at a short rotation speed in the low-speed operation of the motor, the rotation speed can be smoothly controlled without causing rotation unevenness. In particular, even when the inertia of the load is low and high torque is required in low-speed operation, effective speed control can be performed without causing rotation unevenness.

According to the DC brushless motor speed control device of the present invention, when the DC brushless motor is a three-phase motor, the DC brushless motor has a motor drive Hall sensor arranged at every 120 degrees of electrical angle. Since the motor is driven by detecting the rotational position of the rotor, it is not necessary to provide a frequency generator or the like for detecting the rotational speed by sharing these Hall sensors for speed control. Also, three error signal generation circuits are provided according to the rotation position detection signals for three phases, and since the phases of the error signals obtained in each phase are shifted by 120 degrees, the rotation speed obtained by combining these error signals is provided. The control signal is a signal having a cycle including three error signals per rotation.

According to the DC brushless motor speed control device of the third aspect, an error from the reference signal is generated from the rotation speed of the rotor obtained by one rotor position detecting means. This error is equally divided into N by the number N of the rotor position detecting means, and the error is distributed at the timing obtained by each rotor position detecting means to generate a speed control signal. Thus, the control can be performed with a signal having a shorter cycle than when the rotation speed is controlled using the rotation speed of the rotor obtained by one rotor position detection unit. Therefore, even at low speed operation, smooth rotation speed control can be performed without uneven rotation.

According to the DC brushless motor speed control device of the present invention, when the DC brushless motor is a three-phase motor, three DC driving motors arranged at an electrical angle of 120 degrees are driven. One pulse is obtained by one rotation by dividing the output of the first Hall sensor of the Hall sensor by the frequency dividing circuit. From this pulse, an error pulse with respect to the reference clock output from the reference clock generation circuit is generated, and the pulse width adjustment circuit converts the error pulse into a pulse having a width of 1/3. Then, the first and second timing adjustment circuits output speed control pulses at timings related to the second and third Hall sensors. Then, the output of the pulse width adjustment circuit and the outputs of the first and second timing adjustment circuits are synthesized by the synthesis circuit. As a result, it is possible to divide the error obtained from the output of one Hall sensor into three equal parts, to distribute the error at a timing related to each Hall sensor, and to output the control signal.

Further, according to the DC brushless motor speed control device of the present invention, a predetermined acceleration signal is generated in accordance with a target rotation speed while generating a speed error signal by the output of one detecting means. Since the output is performed, for example, at the time of startup, control is performed so as to accelerate to a target rotation speed by an acceleration signal, so that startup can be performed smoothly in a short time. Thereafter, when the rotation speed exceeds the target rotation speed, deceleration control is performed by the speed control signal. Therefore, even if acceleration control is performed by the acceleration signal, the speed is reduced by the speed error signal. The rotation speed can be kept constant.

According to the DC brushless motor speed control device of the present invention, when the DC brushless motor is a three-phase motor, three motor driving units arranged for every 120 degrees of electrical angle are provided. Are shared for controlling the speed of the rotor. One pulse is obtained in one rotation by dividing the output of the first Hall sensor by a frequency dividing circuit. An error signal corresponding to the rotational speed error is generated by the error signal generation circuit from the pulse and the reference clock output from the reference clock generation circuit. Further, an acceleration pulse given by a target rotation speed or the like is generated by an acceleration pulse generation circuit. The first timing adjustment circuit outputs an acceleration pulse at a timing related to the second Hall sensor, and the second timing adjustment circuit outputs an acceleration pulse at a timing related to the third Hall sensor. The synthesis circuit outputs the output of the error signal generation circuit and the outputs of the first and second timing adjustment circuits as a speed control signal to control the speed of the rotor. Therefore, the magnetic pole of the rotor can be detected by the Hall sensor, and a speed error signal is output by the error signal generation circuit using one output. Then, the first timing adjustment circuit and the second timing adjustment circuit output an acceleration signal. Then, the rotation speed of the rotor is controlled by the speed control signal output from the synthesis circuit.

[Brief description of the drawings]

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

FIG. 2 is a waveform diagram showing the operation of the DC brushless motor speed controller.

FIG. 3 is a block diagram of a DC brushless motor speed control device according to a second embodiment of the present invention.

FIG. 4 is a waveform chart showing the operation of the speed control device for the DC brushless motor.

FIG. 5 is a block diagram of a DC brushless motor speed control device according to a third embodiment of the present invention.

FIG. 6 is a waveform chart showing the operation of the DC brushless motor speed controller.

FIG. 7 is a block diagram of a first conventional DC brushless motor speed control device.

FIG. 8 is a block diagram of a second conventional DC brushless motor speed control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC brushless motor 2, 3, 4 Hall element 5, 6, 7 Divider circuit 8, 9, 10 Error signal generation circuit 11 Signal synthesis circuit 12 Reference clock generation circuit (reference signal generation circuit) 15 Pulse width adjustment circuit 16, 17 Timing adjustment circuit 18 Acceleration pulse generation circuit (acceleration signal generation circuit)

Claims (6)

[Claims] 1. A speed control device for a DC brushless motor, comprising: a plurality of rotor position detection means for outputting a rotor position detection signal, wherein the rotation speed of the rotor is kept constant based on the rotor position detection signal. 1 per rotation for each position detection signal
A rotation speed signal generation circuit that generates two rotation speed signals;
A reference signal generating circuit for generating a reference signal corresponding to a target rotation speed of the rotor; and a difference between the rotation speed of the rotor and the target rotation speed by inputting each of the rotation speed signals and the reference signal. An error signal generation circuit for outputting an error signal representing the following, and a circuit for outputting a plurality of error signals from the error signal generation circuit as a rotation speed control signal for the rotor. Control device. 2. A method according to claim 1, wherein said plurality of rotor position detecting means are Hall sensors arranged at an electrical angle of 120 degrees, and said error signal generating circuits are provided in a number corresponding to each Hall sensor. The speed controller for a DC brushless motor according to claim 1. 3. An apparatus according to claim 1, further comprising: N rotor position detecting means for detecting a rotational speed of the rotor, generating an error with respect to a reference signal using an output of the one detecting means, dividing the error into N equal parts, and A speed control device for a DC brushless motor, wherein the speed control signal is output at a timing related to each rotor position detecting means. 4. The first, second, and third Hall sensors provided as the N rotor position detecting means and arranged at every 120 electrical degrees, and the output of the first Hall sensor is divided to divide the output of the first Hall sensor. A frequency divider that outputs one pulse per rotation; a reference clock generator; and an error signal generator that outputs an error pulse corresponding to the rotation speed error signal of the rotor from a reference clock and an output of the frequency divider. A pulse width adjusting circuit that outputs a speed control pulse obtained by converting the error pulse into a pulse having a width of ３, an output of the frequency dividing circuit, an output of the second Hall sensor, and the speed control pulse. A first timing adjustment circuit that outputs the speed control pulse at a timing related to a second Hall sensor; an output of the frequency dividing circuit; an output of a third Hall sensor; A second timing adjustment circuit that outputs the speed control pulse at a timing related to a third Hall sensor, and a synthesis that outputs the output of the pulse width adjustment circuit and the first and second timing adjustment circuits as a speed control signal. The speed controller of a DC brushless motor according to claim 3, comprising a circuit. 5. A motor comprising a plurality of detecting means for detecting a magnetic pole of a rotor, wherein an error with respect to a reference signal is output as a speed error signal using an output of one of the detecting means, and a predetermined acceleration is provided at a timing relating to the other detecting means. A speed controller for a DC brushless motor, which outputs a signal and controls the rotation speed of the rotor with the speed error signal and the acceleration signal. 6. A first, a second, and a third Hall sensor provided as the plurality of detecting means and arranged at every 120 electrical degrees, and the output of the first Hall sensor is frequency-divided for each rotation of the rotor. A frequency divider that outputs one pulse; a reference clock generator; an error signal generator that outputs an error pulse corresponding to a rotation speed error of the rotor from a reference clock and an output of the frequency divider; Acceleration pulse generating means for generating a pulse; an output of the frequency dividing circuit; an output of a second Hall sensor; and a first timing adjustment circuit for outputting the acceleration pulse at a timing related to the second Hall sensor from the acceleration pulse. A second output of the acceleration pulse from the output of the frequency dividing circuit, the output of the third Hall sensor, and the acceleration pulse at a timing related to the third Hall sensor. The speed control device for a DC brushless motor according to claim 5, comprising: a timing adjustment circuit; and a synthesis circuit that outputs an output of the error signal generation circuit and outputs of the first and second timing adjustment circuits as a speed control signal.