JPH10136683A - Control equipment of brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control equipment of a brushless motor which can detect the rotor position with high precision, without the use of a filter. SOLUTION: An induced voltage 8a of a stator winding of a brushless motor 3 is compared with a reference potential 9a, and a phase pulse 10a is obtained. A triggerable timer 11 is driven by the phase pulse 10a, and switching waveform components by PWM of the phase pulse 10a are eliminated. Timers 14, 15 are driven by the upper and the lower arm driving pulses 12a, 13a of a distributing means 5, which controls the electric conduction timing of a switching means 2. By output pluses 14a, 15b of the timers 14, 15, a circulating current conduction interval contained in the phase pulse 10a is masked, and a rotor position signal 17a is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a brushless motor, and more particularly to a control device for a brushless motor having no position sensor capable of detecting a rotor position with high accuracy.

[0002]

2. Description of the Related Art Conventionally, a control device for a brushless motor having no position sensor detects a rotor position from a non-energized phase induced voltage of a stator winding and obtains an energizing pulse based on the detected rotor position. At startup, it operates as a separately-excited inverter to rotate the brushless motor, and when the rotation speed of the brushless motor rises to a value at which the induced voltage can be detected, it operates as a self-excited inverter and the stator winding of the brushless motor , The energizing timing of each phase is detected from the induced voltage, and an energizing pulse is generated based on the detected energizing timing to control the brushless motor. A control device for a brushless motor having no position sensor (hereinafter simply referred to as a control device for a brushless motor) is described in, for example, JP-B-63-201.
No.20 Gazette, etc., and "Introduction to Power Electronics" edited by Eiichi Ohno (published by Ohmsha, 1984).

FIG. 9 is a block diagram showing the configuration of a conventional brushless motor control device. In the figure, reference numeral 1 denotes a DC power supply, 3 denotes a brushless motor, 50 denotes a brushless motor control device. Is the DC power supply 1
DC voltage from the motor is converted to AC voltage and the brushless motor 3
, A rotor position detecting means 4 for detecting an induced voltage from a terminal voltage of a stator winding of the brushless motor 3 and calculating a rotor position from the detected induced voltage, and a stator of the brushless motor 3. A phase switching signal 5a for sequentially switching the current-carrying phase of the winding is supplied to the rotor position detecting means 4.
And a switching unit 2 based on a phase switching signal 5a output from the distribution unit 5.
And a power drive unit 6 for performing PWM control.

FIG. 10 is a block diagram showing the structure of the rotor position detecting means 4 shown in FIG. 9, in which 7 is a comparator,
56 is a band pass filter.

Next, the operation of the conventional control device for a brushless motor configured as described above will be described with reference to FIGS.

[0006] The rotor position detecting means 4 of the brushless motor control device 50 detects the three-phase output (induced voltage of the stator winding) of the switching means 2 and converts the detected three-phase output into a band for each phase. Through the pass filter 56, the PW
The switching waveform of the M control is converted into a smooth analog waveform and the DC component is cut. Then, a neutral point potential is obtained by resistance division from the three-phase filter outputs from which the DC components have been cut, and the calculated neutral point potential is compared with the filter outputs of the respective phases by the comparator 7. The timing of the point at which the output becomes the neutral point potential is determined as the rotor position, and the determined rotor position is output to the distribution means 5.

[0007] Upon receiving this output, the distribution means 5 generates a phase switching signal and outputs this to the power drive means 6.
Upon receiving this output, the power drive unit 6 drives the switching unit 2 on / off based on the phase switching signal to generate an energizing pulse and performs PWM control.

[0008]

However, in the conventional brushless motor control device 50, when detecting the rotor position, the induced voltage of the stator winding is subjected to waveform processing using a band-pass filter 56. Therefore, the phase of the output of the band-pass filter 56 and, consequently, the position of the rotor to be detected change depending on the rotation speed of the brushless motor 3 and the characteristics of the band-pass filter 56, and an appropriate energizing pulse is obtained. Was not always possible. In particular, if the characteristics of the bandpass filter 56 are determined so that the rotor position can be properly detected near the rated rotation speed,
Since the phase shift becomes large at a low frequency, the minimum frequency for switching from the separately-excited type to the self-excited type cannot be set low. As a result, a large starting current flows.

Further, a capacitor for cutting the DC component of the band-pass filter 56 needs to have a high voltage and a large capacity, which has been a problem in terms of cost and miniaturization.

Further, due to the phase shift caused by using the band-pass filter 56, it has been difficult to optimize the efficiency over a wide range of control rotation speed except for a part.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a brushless motor control device capable of detecting a rotor position with high accuracy without using a filter.

[0012]

According to a first aspect of the present invention, there is provided a control device for a brushless motor, wherein a terminal of each phase of a stator winding of the brushless motor is connected between a positive electrode and a negative electrode of a DC power supply. First and second switch elements to be connected,
Switching means having free-wheel diodes connected in parallel to the first and second switch elements, and rotor position detecting means for obtaining a rotor position from an induced voltage of each phase of a stator winding of the brushless motor A distribution means for generating a phase switching signal for energizing the stator windings of each phase of the brushless motor in a certain order based on the determined rotor position; and the switching based on the generated phase switching signal. Turning on the first and second switch elements of the means;
And a power drive unit for performing PWM control on one of the first and second switch elements while driving off, wherein the rotor position detection unit sets the potential of the negative electrode of the DC power supply to ground. A voltage converter for converting the terminal voltage of each phase of the stator winding of the brushless motor into 1 / K (K is a constant) as a potential, and a reference potential conversion for converting the voltage of the DC power supply to 1 / (2K) The output of each phase of the voltage converter and the output of the reference potential converter are compared, and while the output of each phase of the voltage converter is equal to or less than the output of the reference potential converter, Phase pulse generating means for outputting a pulse having the first logic level of the binary signal having the second logic level for each phase,
When the phase switching signal generated by the distribution unit changes so as to turn off the second switch element of each phase of the switching unit, the mask pulse having the first logic level is provided for each phase for a certain time To. When the first mask pulse generating means to be output respectively and the phase switching signal generated by the distribution means change so as to turn off the first switch element of each phase of the switching means, the second mask signal is generated for a certain time To. A second mask pulse generating means for outputting a mask pulse having a logical level of each phase for each phase; and a trigger each time a pulse is output to each phase of the phase pulse generating means. Is longer than the pulse generation period Tc of the PWM control, and
A position pulse generating means for generating a pulse having the first logic level and outputting the pulse for each phase during a time Tm shorter than the certain time To of the mask pulse of the mask pulse generating means; OR operation means for taking, for each phase, the output of each phase of the means, the output of each phase of the position pulse generation means, and the output of each phase of the first mask pulse generation means, and the OR operation means The output of each phase and the second
And AND operation means for outputting the result of ANDing the output of each phase of the mask pulse generation means for each phase for each phase as a rotor position signal.

The brushless motor control device according to the present invention (claim 2) is characterized in that, in the brushless motor control device (claim 1), the first and second mask pulse generating means are adapted to output the mask pulse. In this case, a certain time width To is set to a constant value.

The control device for a brushless motor according to the present invention (claim 3) is the control device for a brushless motor (claim 1), wherein the current detection means for detecting the current of the DC power supply and the current detection means Current-voltage conversion means for converting an output into a voltage proportional to an electrical time constant of a stator winding of the brushless motor and outputting the voltage; and wherein the first and second mask pulse generation means generate a mask pulse. The certain time width To is changed in accordance with the output of the current-voltage conversion means within a range larger than the width Tm of the pulse output by the position pulse generation means.

A brushless motor control device according to the present invention (claim 4) is the brushless motor control device (claim 1) wherein the output of each phase of the phase pulse generating means is generated by the distribution means. Only the first pulse which appears from the point in time when the phase switching signal changes to turn off the second switch element of each phase of the switching means is extracted, and the width of the extracted pulse is detected for each phase. First, from the point in time when the phase switching signal generated by the distribution means of the pulse width detection means and the output of each phase of the phase pulse generation means changes so as to turn off the first switch element of each phase of the switching means. A second pulse width detecting means for extracting only the appearing pulse and detecting the width of the extracted pulse for each phase; A current detecting means for detecting a current, and the first and second pulse width detecting means detecting the current based on a change amount of an output of the current detecting means and an electric time constant of a stator winding of the brushless motor. Pulse width correction means for outputting a pulse width correction amount, wherein the first mask pulse generation means determines the pulse width of each phase detected by the first pulse width detection means by the pulse width correction means. The second mask pulse generating means outputs a mask pulse having the width corrected by the output for each phase. The second mask pulse generating means calculates the pulse width of each phase detected by the second pulse width detecting means. A mask pulse having the width corrected by the output of the pulse width correction means as the width is output for each phase.

The brushless motor control device according to the present invention (claim 5) is the brushless motor control device (any one of claims 1 to 4), wherein the power drive means includes a pulse for PWM control. A signal generated by a triangular wave generator, wherein the position pulse generating means generates the peak of the triangular wave output of the triangular wave generator, which is located within the pulse width of the generated pulse signal for PWM control. PWM timing pulse generating means for detecting timing; detecting the presence or absence of a pulse output from the phase pulse generating means at the timing detected by the PWM timing pulse generating means; And a position pulse synthesizing means for holding the logical level of the above until the next detected timing. One in which the.

The control device for a brushless motor according to the present invention (claim 6) is the control device for a brushless motor according to any one of claims 1 to 5, wherein the phase pulse generating means is driven from the output of the DC power supply. And a control power supply for generating a DC voltage to be applied, and the output of the phase pulse generating means is input to the position pulse generating means via a photocoupler.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a block diagram showing a configuration of a control device for a brushless motor according to a first embodiment of the present invention. In the drawing, reference numeral 1 denotes a DC power supply, 3 denotes a three-phase brushless motor, and 50 denotes a control device for a brushless motor. The control device 50 converts the DC voltage from the DC power supply 1 into an AC voltage to drive the brushless motor 3, and detects the induced voltage from the terminal voltage of the stator winding of the brushless motor 3. Rotor position detecting means 4 for calculating the rotor position from the induced voltage obtained, brushless motor 3
A distribution means 5 for generating a phase switching signal 5a for sequentially switching the energized phases of the stator windings based on the output of the rotor position detection means 4, and a phase switching signal 5a output from the distribution means 5
Drives the switching means 2 on the basis of
It comprises a power drive means 6 for controlling.

The switching means 2 comprises three pairs of first and second switch elements 51u, 52 connected in series.
u, 51v, 52v, 51w, 52w are connected in parallel between the positive electrode and the negative electrode of the DC power supply 1, and the first and second switch elements 51u, 52u, 51v, 52v, 51w,
Freewheeling diodes 53u, 54u in parallel with each of 52w,
53v, 54v, 53w, 54w are respectively connected,
The midpoint between the first switch elements 51u, 51v, 51w and the second switch elements 52u, 52v, 52w of each pair is connected to the U, V, W phase terminals of the stator winding of the brushless motor 3, respectively. Have been. A first switch element (hereinafter, referred to as an upper arm) 51u, 51v, 51w, and a second switch element (hereinafter, referred to as a lower arm) 5
2u, 52v, and 52w are each made of an IGBT, and the upper arms 51u, 51v, 51w and the lower arms 52u, 52u,
The power drive means 6 is connected to each gate of 52v and 52w.
From the drive signal 6a.

The rotor position detecting means 4 is provided with an operation block for each of U, V, and W phases of the brushless motor 3, and only the U-phase operation block is shown in FIG. The same applies to the operation blocks of other phases. Each operation block includes a voltage converter 8 that shifts and detects terminal voltages Vu, Vv, Vw of each phase of a stator winding of the brushless motor 3 to a predetermined level, and a voltage 1a of the DC power supply 1 for the stator winding. And a reference potential converter 9 for converting the reference potential to a reference potential corresponding to the midpoint potential of each phase.
Phase pulse generating means 10 for outputting a pulse while falling below the output 9a, and a retriggerable position pulse generating means 1 for outputting a pulse having a predetermined width Tm every time triggered by a pulse of an output 10a of the phase pulse generating means 10.
1. First mask pulse generating means 14 for generating a mask pulse having a constant width To based on output 13a of lower arm driving pulse generating means 13 of distribution means 5, output 12a of upper arm driving pulse generating means 12 of distribution means 5 The second mask pulse generating means 15 which generates a mask pulse having a constant width To based on the above, outputs an inverted output thereof, the output 10a of the phase pulse generating means 10, and the output 11 of the position pulse generating means 11
a and the output 14a of the first mask pulse generation means 14.
OR circuit 16 that takes OR, and output 1 of OR circuit 16
6a and the output 15 of the second mask pulse generating means 15
It is composed of an AND circuit 17 for ANDing a.

Here, the position pulse generating means 11 comprises a retriggerable timer retriggered by the next pulse input, for example, a retriggerable one-shot multivibrator. Further, the width Tm of the pulse generated by the position pulse generator 11 can be removed from the output 10a of the phase pulse generator 10 by the mask pulse of the second mask pulse generator 15 while eliminating the influence of the PWM control waveform. Thus, it is necessary that the pulse width is longer than the pulse generation period Tc of the PWM control of the power drive means 6 and shorter than the width To of the mask pulse of the second mask pulse generation means. In order to reduce the detection error, it is preferable to be as short as possible.
In the first embodiment, the pulse generation period Tc of the PWM control
It is slightly longer.

The width To of the mask pulse generated by the first and second mask pulse generators 14 and 15 is set to a value longer than the conduction period Td of the free-wheeling diode described later.

Reference numerals 12 and 13 denote U-phase ones of the upper-arm drive pulse generator and the lower-arm drive pulse generator provided for generating the phase switching signal of the distribution means 5 for each phase. Is shown.

FIG. 2 is a timing chart showing the operation of the rotor position detecting means shown in FIG. 1. FIG. 2 (a) shows the output waveform of the upper arm driving pulse generator, and FIG. 2 (b) shows the lower waveform. FIG. 2C shows an output waveform of the arm drive pulse generator, and FIG. 2C shows an output waveform of the voltage converter and the reference potential converter.
(d) is a diagram showing the output waveform of the phase pulse generating means, FIG.
(e) is a diagram showing the output waveform of the position pulse generating means, FIG.
FIG. 2 (f) shows the output waveform of the first mask pulse generating means, FIG. 2 (g) shows the output waveform of the OR circuit, FIG. 2 (h)
FIG. 2 is a diagram showing an output waveform of the second mask pulse generating means, and FIG. 2 (i) is a diagram showing an output waveform of the AND circuit.

Next, the operation of the control device for a brushless motor according to the first embodiment configured as described above will be described with reference to FIGS.
2 will be described. Here, the U-phase will be described as an example, and the switching means 2 includes the lower arms 52u and 52u.
It is assumed that PWM control is performed on v and 52w.

Upper arm drive pulse generator 1 for distribution means 5
2 outputs the drive pulse 12a so that it turns off at time t1 and turns on at time t6 after a lapse of 240 degrees in phase angle, as shown in FIG. 2 (a).

Further, as shown in FIG. 2B, the lower arm drive pulse generator 13 of the distribution means 5 has a phase angle after the drive pulse 12a of the upper arm drive pulse generator 12 is turned off at time t1. The driving pulse 13a is output so as to be turned on at time t3 after elapse of 60 degrees and turned off at time t4 after elapse of 120 degrees in phase angle.

These upper arm drive pulse generators 12,
The output of the lower-arm drive pulse generator 13 is input to the power drive unit 6 as a phase switching signal 5a, converted into a drive signal 6a, and input to the U-phase upper arm 51u and lower arm 52u of the switching unit 2, respectively. You.

On the other hand, when the terminal voltage of the stator winding of the brushless motor 3 is input to the voltage converter 8 of the rotor position detecting means 4, the voltage converter 8 converts this to 1 / K (K is a constant).
And level-shifted to output.

The reference potential converter 9 level-shifts the output voltage of the DC power supply 1 to 1 / (2K) so as to be a reference potential corresponding to the neutral point potential of each phase of the brushless motor, and outputs it. .

Here, as shown in FIG. 2C, the output 9a of the reference potential converter 9 corresponds to the output voltage of the DC power supply 1 as Edc.
Then, Edc / 2K is constant, but the output 8a of the voltage converter 8 changes as follows with the operation of the switching means 2. That is, in the switching means 2, when the drive signal 6a is input and the drive pulse 12a of the upper arm drive pulse generator 12 is turned off at time t1, the upper arm 51u is turned off, and the U-phase enters the non-energizing period. , The free-wheeling diode 54u of the lower arm conducts. When the reflux diode 54u conducts, the voltage converter 8
Output 8a is substantially the potential of the negative electrode of the DC power supply 1 (GND)
, And remains at this potential during the conduction period represented by Td. Next, when the freewheeling diode 54u is turned off, the output 8a of the voltage converter 8 has a waveform in which the PWM control pulse is superimposed on the induced voltage of the own phase due to the influence of the switching of the other phase.

Next, when the drive pulse 13a of the lower arm drive pulse generator 13 is turned on at time t3, the lower arm 5
2u is turned on and PWM controlled, and the output 8 of the voltage converter 8
“a” is a PWM control waveform over a period of a phase angle of 120 degrees.

Next, when the lower arm 52u turns off at time t4, the free-wheeling diode 53u of the upper arm conducts,
The output 8a of the voltage converter 8 outputs Edc / Dc during the conduction period Td.
K, and thereafter, during the period from when the freewheeling diode 53u turns off and when the upper arm 51u turns on next, the output 8a of the voltage converter 8 returns to the induced voltage of its own phase due to the influence of another phase.
It becomes a waveform on which the WM control waveform is superimposed.

Next, the output 8a of the voltage converter 8 and the output 9a of the reference potential converter 9 are received, and the phase pulse
When the output 8a of the voltage converter 8 is equal to or less than the output 9a of the reference potential converter 9, a pulse of "H" level is output, and as shown in FIG. A period Tp between times t2 and t5 at which the terminal voltage of the stator winding having a single pulse at Td and superimposed on the PWM control waveform in FIG.
And outputs a waveform having a pulse train corresponding to the PWM control waveform (10a).

Next, the output 1 of the phase pulse generating means 10
0a, the position pulse generating means 11 sets the pulse width Tm of the output 10a of the phase pulse generating means 10 to Tm whose width is slightly larger than the PWM control cycle Tc.
2 (e), whereby the PWM is output from the output 10a of the phase pulse generating means 10 as shown in FIG.
The control waveform is removed and output (11a).

On the other hand, upon receiving the output of the drive pulse 13a from the lower arm drive pulse generator 13, the first mask pulse generating means 14 outputs the drive pulse 13a as shown in FIG.
At the falling edge, a single pulse (mask pulse) having a constant time width To longer than the conduction period Td of the freewheeling diode is output (14a).

Further, upon receiving the output of the drive pulse 12a from the upper arm drive pulse generator 12, the second mask pulse generating means 15 outputs the drive pulse 12a as shown in FIG.
Generates a mask pulse having the above-mentioned time width To, and inverts and outputs the generated output (15).
a).

Next, the output 1 of the phase pulse
0a, the output 11a of the position pulse generating means 11 and the first
Receiving the output 14a of the mask pulse generating means 14, the OR circuit 16 determines the OR of the output 10a of the phase pulse generating means 10, the output 11a of the position pulse generating means 11, and the output 14a of the first mask pulse generating means 14. As a result, the position pulse generating means 11 shown in FIG.
The waveform during the conduction period of the free-wheeling diode of the lower arm is removed from the output 11a, and an output having the waveform shown in FIG. 2 (g) is output (16a). However, when the duty ratio of the pulse of the PWM control becomes 100%, the phase pulse generating means 1
While the output 10a of 0 has a waveform having two pulses in the period Tp with the flywheel diode conduction period Td interposed therebetween, the output 11a of the position pulse generating means 11 is different from FIG. 2g, the output 10a of the phase pulse generating means 10 removes the effect of the conduction period Td of the lower arm freewheeling diode and outputs the waveform shown in FIG. 2 (g). (16
a).

Next, the output 16a of the OR circuit 16 and the second
The AND circuit 17 receives the output 15a of the OR circuit 16 and the output 15a of the second mask pulse generating means 15, thereby obtaining the AND of the output 15a of the second mask pulse generating means 15 as shown in FIG. As shown in FIG.
From the output 16a, the influence of the conduction period Td of the free-wheeling diode of the upper arm is removed, and this is output to the distribution means 5 as a rotor position signal (17a).

Here, the rotor position is obtained from a comparison between the induced voltage of the pure stator winding, which is not affected by the power supply circuit, and the midpoint potential of the DC power supply voltage. In this example, the position where the induced voltage of the stator winding becomes the midpoint potential of the DC power supply voltage is detected as the position of the rotor. For this reason, the rotor position signal detects the timing at which the induced voltage of the pure stator winding unaffected by the power supply circuit crosses the midpoint potential of the DC power supply voltage,
Ideally, it has a single pulse waveform so as not to cause a malfunction. On the other hand, the rotor position signal 17a obtained as described above is different from the free-wheeling diode conduction period Td or Pd.
The influence of the WM control waveform is removed, and a preferable single pulse waveform is obtained. The detected rotor position is shown in FIG.
As is apparent from FIG. 2C, the induced voltage on which the PWM control waveform is superimposed is compared with the reference potential. Has a maximum error of about Tc / 2 due to the set width of the generated pulse, but if the PWM cycle is sufficiently short with respect to the phase switching cycle, the detection accuracy of the rotor position is hardly affected. As a result, practically accurate rotor position detection can be realized.

The phase pulse generating means 10, position pulse generating means 11, first mask pulse generating means 1
4, second mask pulse generating means 15, OR circuit 16,
The function of the AND circuit 17 may be realized by using software in an arithmetic unit.

As described above, in the first embodiment, the detected terminal voltages Vu, Vv,
Retriggerable PWM control waveform from Vw
As a result, the influence of the diode conduction period Td is removed by the masking pulses 14a and 15a, and the rotor position is detected. Therefore, as in the conventional example using a band-pass filter, an error occurs in the rotor position detection due to a phase shift. Does not occur, and highly accurate rotor position detection is possible. As a result, stable starting characteristics and high-efficiency driving over a wide range can be realized.

Also, in the first embodiment, the first,
In addition, since the second mask pulse generating means 14 and 15 have the time width To of the masking pulses 14a and 15a set to a constant value, the configuration can be simplified.

Embodiment 2 FIG. 3 is a block diagram showing a configuration of a control device for a brushless motor according to a second embodiment of the present invention. In the drawing, the same reference numerals as those in FIG. Generator for generating a PWM control waveform of
9 is a PWM timing pulse generating means for detecting the timing of the peak of the triangular wave output from the triangular wave generator 18 which is located within the generated PWM control pulse width, and 20 is detected by the PWM timing pulse generating means 19. A position pulse synthesizing unit that detects the presence or absence of a pulse output from the phase pulse generating unit 10 at a timing and, when there is a pulse to be output, holds the output logic level of the pulse. The position pulse synthesizing means 20 constitutes the position pulse generating means 11. The second embodiment shows a preferred configuration example of the position pulse generator 11 in the first embodiment.

FIG. 4 is a timing chart for explaining the operation of the position pulse generating means of FIG. 3. FIG. 4 (a) shows the output of the triangular wave generator and the modulated wave, and FIG. 4 (b). Is PW
FIG. 4C shows the output of the phase pulse generator, FIG. 4D shows the output of the PWM timing pulse generator, and FIG. 4E shows the output of the position pulse synthesizer. It is a figure showing an output.

Next, the operation of the control device for a brushless motor configured as described above will be described with reference to FIGS.

In the power drive means 6, the triangular wave generator 18 outputs a triangular wave. As shown in FIG. 4 (a), the output triangular wave is compared with the modulated wave 60 and shown in FIG. 4 (b). Generate a PWM signal.

The waveform of the generated PWM signal is input to the phase pulse generator 10 through the voltage converter 8 as a superimposed waveform of the induced voltage and a PWM control waveform of its own phase, as shown in FIG. Period T of phase pulse generating means 10
A waveform corresponding to the PWM control waveform appears at p.

On the other hand, upon receiving the output 18a of the triangular wave generator 18, the PWM timing pulse generating means 19 performs the operation shown in FIG.
As shown in (1), the timing of the lower peak of the output triangular wave is detected and output (19a).

Next, upon receiving this output 19a, the position pulse synthesizing means 20 outputs the PWM timing pulse detecting means 1
9 detects the logic level of the output 10a of the phase pulse generator 10 at the timing detected by the
When the output 10a of "0" is at "H" level, it outputs "H" level and holds it until the next detection timing, and when the output 10a is at "L" level, it inverts it to "L" level and changes it to the next level. As shown in FIG. 4 (e), the PWM control waveform in the period Tp is removed from the output 10a of the phase pulse generator 10 and the removed pulse is used as the position pulse generator 11 as shown in FIG. (11a).

The functions of the PWM timing pulse generating means and the position pulse synthesizing means 20 may be realized by using software in an arithmetic unit.

As described above, in the third embodiment, the position pulse generating means 11 is controlled at the timing detected from the peak located within the PWM control pulse width of the output of the triangular wave generator 18 for performing the PWM control. The presence / absence of a pulse output from the phase pulse generating means 10 is detected, and when a pulse is output, the logic level of the pulse is held until the next timing.
Phase pulse generating means 1 according to the timing of WM control
Provided is a control device for a brushless motor having a retriggerable position pulse generation unit 11 capable of detecting the presence or absence of a pulse train output from 0 and reliably removing the influence of a PWM control waveform from an output 10a of a phase pulse generation unit. be able to.

Embodiment 3 FIG. 5 is a block diagram showing the configuration of a control device for a brushless motor according to the third embodiment. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and 21 denotes the current of the DC power supply 1. The current detecting means 22 for detecting is a current-to-voltage converting means for converting the output of the current detecting means 21 into a voltage proportional to the electrical time constant of the stator winding of the brushless motor 3. Is input to the first and second mask pulse generators 14 and 15, and the mask pulse generator 1
At steps 4 and 15, a mask pulse having a width obtained by changing a certain time width To in proportion to the output of the current-voltage conversion means 22 is output. Embodiment 3
Is such that the width To of the mask pulse generated by the first and second mask pulse generating means 14 and 15 of the first embodiment is variable.

Here, mask pulse generating means 14 and 15
The width of the mask pulse generated in step (1) is set so as not to be less than the width Tm of the pulse output by the position pulse generator due to the logical processing of the waveform.

The current / voltage converting means 22 and the mask pulse generating means 14 and 15 are composed of, for example, a mono-multivibrator for the mask pulse generating means 14 and 15 and the output of the current / voltage converting means 22 is output from the mono-vibrator. This can be realized by using a charging power supply that determines the output cycle of the multivibrator.

FIGS. 6A and 6B are diagrams for explaining the operation of the control device for the brushless motor shown in FIGS. 5A and 5B. FIG. 6A is a diagram showing an energized state at a phase switching timing, and FIG. FIG. 6C is a graph showing a change in the W-phase terminal voltage of the stator winding of the motor, and FIG. 6C is a graph showing a change in the W-phase current of the stator winding of the brushless motor.

Next, the operation of the control device for a brushless motor configured as described above will be described with reference to FIGS.

Here, the phase switching operation will be described taking switching from the W phase to the U phase as an example.

In the phase switching operation from the W phase to the U phase, as shown in FIG.
The upper arm 51w of the phase and the lower arm 52v of the V phase are turned on, then the upper arm 51u of the U phase is turned on, and then the upper arm 51w of the W phase is turned off.

With this operation, the W-phase terminal voltage Vv becomes
As shown in FIG. 6 (b), while the upper arm 51w of the W-phase is on at first, the potential of the positive electrode of the DC power supply 1 is Edc, and then the upper arm 51w of the W-phase is turned off. , W flowing through the W-phase flows through the free-wheeling diode 54w, and thus has a potential lower than the potential (GND) of the negative electrode of the DC power supply 1 by the forward voltage drop of the free-wheeling diode 54w.

At this time, the W-phase current iw flows until the energy of the W-phase inductance attenuates.
As shown in FIG. 6 (c), it attenuates to zero during the period of Td. Since the attenuation gradient of the W-phase current iw is determined by the electric time constant of the stator winding, the larger the W-phase current iw, the longer the free-wheeling diode conduction period Td.

On the other hand, in FIG. 5, the current of the DC power supply 1 is detected by the current detecting means 21, and the detected current is proportional to the electric time constant of the stator winding of the brushless motor 3 by the current-voltage converting means 22. The first and second mask pulse generating means 1 are converted into a voltage and the converted voltage output is used.
The width of the mask pulse generated in steps 4 and 15 is changed in proportion to the current of the DC power supply 1, that is, the current of each phase and the electrical time constant.

Therefore, it is possible to obtain a mask pulse capable of stably removing the influence of the free-wheeling diode conduction period Td even if the current of each phase changes.

The functions of the current-voltage converter 22 and the mask pulse generators 14 and 15 may be realized by using software in an arithmetic unit.

As described above, in the third embodiment, the width of the mask pulse is changed in proportion to the current of the DC power supply 1 and the electric time constant of the stator winding of the brushless motor. Therefore, the width of the mask pulse is corrected by the motor current, and the free-wheeling diode conduction period Td can be masked in accordance with the operation state. As a result, stable and accurate rotor position detection can be performed. Can be.

Embodiment 4 FIG. 7 is a block diagram showing the configuration of a control device for a brushless motor according to the fourth embodiment. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.
First, only the pulse which first appears from the falling timing of the output signal of the lower arm drive pulse generator 13, that is, the pulse of the free-wheeling diode conduction period Td, is taken out, the time width is measured, and this is used as the first mask pulse generating means. 1
The first pulse width detecting means 24 which outputs the pulse signal of the phase pulse generating means 10 is a pulse of the free-wheeling diode conduction period Td which is a pulse which first appears from the falling timing of the output signal of the upper arm drive pulse generator 12. This is a second pulse width detecting means for extracting only the time, measuring the time width thereof, and outputting the measured time width to the second mask pulse generating means 15. 25 calculates the correction amount of the free-wheeling diode conduction period Td from the change amount of the output of the current detection means 21 and the electric time constant of the stator winding of the brushless motor 3, and calculates
This is a pulse correction means for outputting to the first mask pulse generation means 14 and the second mask pulse generation means 15, and the first mask pulse generation means 14 corrects the pulse output to the output of the first pulse width detection means 23. A mask pulse having a time width obtained by adding the outputs of the means 25 is output.
The mask pulse generating means 15 outputs a mask pulse having a time width obtained by adding the output of the pulse correcting means 25 to the output of the second pulse width detecting means 24, and outputs an inverted signal of this output.

Here, the width of the mask pulse of the first and second mask pulse generating means 14 and 15 is set so as not to be less than the width Tm of the pulse output from the position pulse generating means due to the logical processing of the waveform. Keep it.

Further, the first pulse width detecting means 23, the second
The functions of the pulse width detecting means 24 and the pulse correcting means 25 may be realized by using software in an arithmetic unit.

As described above, in the fourth embodiment, the actual free-wheeling diode conduction period Td is measured, and the measured time width Td corrected by the change in current is used as the mask pulse width. In addition, it is possible to obtain a mask pulse in which the accuracy of the width of the generated mask pulse is high and the influence of the free-wheeling diode conduction period Td can be removed more stably. As a result, more stable and accurate rotor position detection can be performed.

Embodiment 5 FIG. FIG. 8 is a block diagram showing a configuration of a control device for a brushless motor according to the fifth embodiment. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. This is a control power supply in which a resistor and a Zener diode are connected in series between the negative electrode and a DC voltage is obtained from both ends of the Zener diode. Reference numeral 27 denotes a photocoupler. The output of the phase pulse generator 10 is input to the primary side of the photocoupler 27, and the output of the secondary side is input to the position pulse generator 11.

With such a configuration, the power supply of the phase pulse generating means 10 on the high voltage side can be configured with a simple circuit, and the high voltage insulation of the rotor position detecting means can be easily realized with a simple configuration. it can.

[0072]

As described above, according to the control apparatus for a brushless motor according to the first aspect of the present invention, the PWM control waveform can be retriggered from the detected terminal voltage of the brushless motor by the pulse generating means, so that the diode conduction period can be reduced. Since the influence is removed by the masking pulse and the rotor position is detected, unlike the conventional example using a band-pass filter, no error occurs in the rotor position detection due to phase shift, and high accuracy is achieved. Of the rotor position can be detected. As a result, stable starting characteristics and high-efficiency driving over a wide range can be realized.

According to the control device for a brushless motor according to the second aspect of the present invention, the first and second mask pulse generating means are such that the time width To of the masking pulse is set to a constant value. Therefore, the configuration can be simplified.

According to the control device for a brushless motor according to the third aspect of the present invention, the width of the mask pulse is changed in proportion to the current of the DC power supply and the electric time constant of the stator winding of the brushless motor. As a result, the width of the mask pulse is corrected by the motor current, so that the free-wheeling diode conduction period can be masked in accordance with the operation state. As a result, stable and accurate rotor position detection can be performed. It can be performed.

According to the control device for a brushless motor of the fourth aspect of the present invention, the actually detected free-wheeling diode conduction period corresponds to the change in the current of the DC power supply and the electrical time of the stator winding of the brushless motor. Corrected by a constant,
Since the width of the mask pulse is used, more stable and accurate rotor position detection can be performed.

According to the control apparatus for a brushless motor according to the fifth aspect of the present invention, the position pulse generating means includes a PW
Detecting the presence or absence of a pulse output from the phase pulse generating means at a timing detected from the peak located within the PWM control pulse width of the output of the triangular wave generator performing M control;
When there is a pulse to be output, the logic level of the pulse is held until the next timing. Therefore, the presence or absence of a pulse train output from the phase pulse generation means is detected in accordance with the PWM control timing. Thus, it is possible to provide a brushless motor control device having a retriggerable position pulse generation unit that can reliably remove the influence of the PWM control waveform from the output of the phase pulse generation unit.

According to the brushless motor control device of the present invention, there is provided a control power supply for generating a DC voltage for driving the phase pulse generating means from the output of the DC power supply, and the output of the phase pulse generating means is provided. Is input to the position pulse generating means via the photocoupler, so that the power supply of the phase pulse generating means on the high voltage side can be configured with a simple circuit, and the high voltage insulation of the rotor position detecting means can be easily performed with a simple configuration. Can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a control device for a brushless motor according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the rotor position detecting means of FIG. 1, showing an output waveform of an upper arm drive pulse generator (FIG. 2 (a)), and an output of a lower arm drive pulse generator. FIG. 2 (b) shows a waveform, FIG. 2 (c) shows an output waveform of a voltage converter and a reference potential converter, and FIG. 2 (d) shows an output waveform of a phase pulse generator. )), A diagram showing the output waveform of the position pulse generator (FIG. 2 (e)), a diagram showing the output waveform of the first mask pulse generator (FIG. 2 (f)), and a diagram showing the output waveform of the OR circuit. FIG. 2 (g), a diagram showing the output waveform of the second mask pulse generating means (FIG. 2 (h)), and a diagram showing the output waveform of the AND circuit (FIG. 2 (i)).

FIG. 3 is a block diagram illustrating a configuration of a control device for a brushless motor according to a second embodiment of the present invention.

FIG. 4 is a timing chart for explaining the operation of the position pulse generating means of FIG. 3, showing the output of the triangular wave generator and the modulated wave (FIG. 4 (a)), and the figure showing the PWM signal ( FIG. 4 (b)) is a diagram showing the output of the phase pulse generating means (FIG. 4 (b)).
(c)), a diagram showing the output of the PWM timing pulse generator (FIG. 4 (d)), and a diagram showing the output of the position pulse synthesizer (FIG. 4 (e)).

FIG. 5 is a block diagram showing a configuration of a control device for a brushless motor according to a third embodiment of the present invention.

6 is a diagram for explaining the operation of the control device for the brushless motor shown in FIG. 5, showing a state of energization at a phase switching timing (FIG. 6 (a)), and showing a stator winding of the brushless motor. FIG. 6 (b) is a graph showing the change in the terminal voltage of the W phase, and FIG. 6 (c) is a graph showing the change in the current of the W phase of the stator winding of the brushless motor.

FIG. 7 is a block diagram showing a configuration of a control device for a brushless motor according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a control device for a brushless motor according to a fifth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a conventional brushless motor control device.

FIG. 10 is a circuit diagram showing a configuration of a conventional rotor position detecting means.

[Description of Signs] 1 DC power supply 1a Voltage of DC power supply 2 Switching means 3 Brushless motor 4 Rotor position detection means 5 Distribution means 6 Power drive means 6a Drive signal 7 Comparator 8 Voltage converter 8a Output of voltage converter 9 Reference Potential converter 9a Output of reference potential converter 10 Phase pulse generator 10a Output of phase pulse generator 11 Position pulse generator 11a Output of position pulse generator 12 Upper arm drive pulse generator 12a Output of upper arm drive pulse generator 13 Lower arm drive pulse generator 13a Output of lower arm drive pulse generator 14 First mask pulse generator 14a Output of first mask pulse generator 15 Second mask pulse generator 15a Second mask pulse generator Output 16 OR circuit 16a OR circuit output 17 amp Circuit 17a Output of AND circuit 18 Triangular wave generator 18a Output of triangular wave generator 19 PWM timing pulse generating means 19a Output of PWM timing pulse generating means 20 Position pulse synthesizing means 21 Current detecting means 22 Current voltage converting means 23 First pulse width Detection means 24 second pulse width detection means 25 pulse correction means 26 control power supply 25 27 photocoupler 50 brushless motor control circuit 51u, 51v, 51w upper arms 52u, 52v, 52w lower arms 53u, 53v, 53w, 54u, 54v , 54w freewheeling diode 56 bandpass filter 60 modulated wave

Claims (6)

[Claims] A first switch element connected between a terminal of each phase of a stator winding of a brushless motor and a positive electrode and a negative electrode of a DC power supply; Switching means having free-wheeling diodes respectively connected in parallel to the switch element; rotor position detecting means for obtaining a rotor position from an induced voltage of each phase of the stator winding of the brushless motor; rotor position obtained above And a distribution unit for generating a phase switching signal for energizing the stator windings of each phase of the brushless motor in a certain order based on the first and second switching units based on the generated phase switching signal. The switch element is turned on / off, and one of the first and second switch elements is set to P
A brushless motor having power drive means for performing WM control, wherein the rotor position detecting means sets the terminal voltage of each phase of the stator winding of the brushless motor to 1 / A voltage converter for converting to K (K is a constant); a reference potential converter for converting the voltage of the DC power supply to 1 / (2K); an output of each phase of the voltage converter; The output is compared with the output, and while the output of each phase of the voltage converter is equal to or lower than the output of the reference potential converter, the first logical level of the binary signal having the first and second logical levels is obtained. A phase pulse generating means for outputting a pulse for each phase; and a phase switching signal generated by the distributing means changes to turn off the second switch element of each phase of the switching means. the above First mask pulse generating means for outputting a mask pulse having a first logical level for each phase, and a phase switching signal generated by the distribution means for turning off the first switch element of each phase of the switching means. The second mask pulse generating means for outputting the mask pulse having the second logic level for each phase for a certain time To, and outputting a pulse to each phase of the phase pulse generating means. The time Tm is longer than the pulse generation period Tc of the PWM control of the power drive unit and shorter than the certain time To of the mask pulse of the first and second mask pulse generation units. A position pulse generating means for generating a pulse having the first logic level and outputting the pulse for each phase; OR operation means for taking, for each phase, an output of each phase of the position pulse generation means and an output of each phase of the first mask pulse generation means, and an output of each phase of the OR operation means, 2. A control device for a brushless motor, comprising: AND operation means for outputting, as a rotor position signal, a result of ANDing the output of each phase of the mask pulse generation means with each phase for each phase. 2. The control device for a brushless motor according to claim 1, wherein said first and second mask pulse generating means are configured to set the certain time width To of the mask pulse to a constant value. Characteristic brushless motor control device. 3. The brushless motor control device according to claim 1, wherein current detection means for detecting a current of the DC power supply, and an output of the current detection means for detecting an electric current of a stator winding of the brushless motor. Current and voltage conversion means for converting the voltage into a voltage proportional to a constant and outputting the voltage; and wherein the first and second mask pulse generation means output the certain time width To of the mask pulse by the position pulse generation means. A control device for controlling the brushless motor, wherein the control value is changed in accordance with the output of the current-voltage conversion means within a range larger than a pulse width Tm of the motor. 4. The control device for a brushless motor according to claim 1, wherein a phase switching signal generated by said distributing means of each phase output of said phase pulse generating means is a second signal of each phase of said switching means. First pulse width detection means for extracting only the first pulse that appears from the time when the switching element is turned off, and detecting the width of the extracted pulse for each phase; Of the output, the phase change signal generated by the distribution means changes only to turn off the first switch element of each phase of the switching means, and only the pulse which appears first is extracted, and the width of the extracted pulse is determined. Second pulse width detection means for detecting each phase, current detection means for detecting the current of the DC power supply, and output of the current detection means. And a pulse width correction means for outputting a correction amount of the pulse width detected by the first and second pulse width detection means on the basis of the amount of change and the electric time constant of the stator winding of the brushless motor. The first mask pulse generating means outputs a mask pulse having a width obtained by correcting the pulse width of each phase detected by the first pulse width detecting means with the output of the pulse width correcting means to each phase. The second mask pulse generating means corrects the pulse width of each phase detected by the second pulse width detecting means with the output of the pulse width correcting means, A brushless motor control device for outputting a mask pulse for each phase. 5. The control device for a brushless motor according to claim 1, wherein said power drive means generates a pulse signal for said PWM control by a triangular wave generator. The pulse generation means includes: a PWM timing pulse generation means for detecting a timing of a peak of a triangular wave output of the triangular wave generator, which is located within a pulse width of the generated pulse signal for PWM control; Detects the presence or absence of a pulse output from the phase pulse generator at the timing detected by the pulse generator,
A control device for a brushless motor, comprising: a position pulse synthesizing means for holding a logical level of a pulse when there is a pulse to be output until the next detected timing. 6. The control device for a brushless motor according to claim 1, further comprising: a control power supply for generating a DC voltage for driving said phase pulse generating means from an output of said DC power supply; A control device for a brushless motor, wherein an output of a pulse generator is input to the position pulse generator via a photocoupler.