JPH0614580A - Motor controller - Google Patents

Abstract

(57) [Summary] [Purpose] A motor that can detect the rotation angle of the motor with high accuracy and perform commutation control, and that can maximize the output torque of the motor. The purpose is to realize a control device. [Structure] A disc-shaped code plate is formed with light-transmitting slits at a constant pitch along a circumferential direction, the code plate is connected to a rotor of a brushless motor, and the light-transmitting slit is irradiated with light.
In a motor control device that obtains a signal for commutation control of a motor based on the light passing through the translucent slit, the width is si
A translucent slit that changes according to the n function is formed on the code plate, and commutation control of the brushless motor is performed based on the detection signal of the light passing through the translucent slit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor controller for controlling commutation of a brushless motor by using a detection signal of an optical encoder.

[0002]

2. Description of the Related Art Conventionally, as a control device for such a motor, there has been, for example, a structure shown in FIG. In Figure 5,
Reference numeral 1 is a brushless motor for which commutation control is performed. The coil of this motor 1 is a three-phase coil. Reference numeral 2 is a disc-shaped code plate, which is connected to the rotor of the motor 1 and has light-transmitting slits 3, 4, and 5 formed in three rows along the circumferential direction. 6, 7, and 8 are transparent slits 3, 4, and 5.
, 10 and 11 are optical sensors for detecting the light passing through the respective light-transmitting slits, and 12 is a commutation control of the motor 1 based on the detection signals of the optical sensors 9, 10, and 11. It is a commutation controller.

FIG. 6 is a view showing the shapes of the translucent slits 3, 4, 5 formed on the code plate 2. In FIG. 6, the translucent slits 3, 4 and 5 have a constant radial width of the code plate 1, and three slits are formed in each row at a constant pitch. The translucent slits 3, 4, 5 are out of phase with each other by 1/6 pitch. FIG. 7 is a waveform diagram of detection signals of the optical sensors 9, 10, and 11. In FIG. 7, the u-phase signal, the v-phase signal, and the w-phase signal are detection signals of the optical sensors 9, 10, and 11, respectively. These signals are out of phase by 1/6 pitch.

In such a motor control device, the translucent slits in each row are out of phase by 1/6 pitch, so that the u-phase v-phase and w-phase signals are 1/6 pitches apart from the code plate. It changes with each rotation. As a result, the detection resolution of the rotation angle becomes 1/6 pitch. However, sufficient detection accuracy cannot be obtained with a resolution of 1/6 pitch. Further, the detection value obtained based on the u-phase v-phase and w-phase signals changes stepwise each time the code plate rotates by 1/6 pitch, so that a commutation timing is delayed. . For example, in a brushless motor, when the phase difference between the teeth of the rotor and the teeth of the stator becomes ¼ pitch, the maximum torque can be output by setting the excitation current of the motor coil to the maximum value.
However, in the above-described conventional example, the timing of maximizing the exciting current is missed due to the delay of the commutation timing. As a result, there is a problem that the output torque of the motor cannot be sufficiently exhibited.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to detect the rotation angle of a motor with high accuracy and perform commutation control. It is an object of the present invention to realize a motor control device that can maximize the output torque that it has.

[0006]

The present invention is a motor control device configured as follows. (1) A transparent slit is formed on a disc-shaped code plate at a constant pitch along a circumferential direction, the code plate is connected to a rotor of a brushless motor, and the transparent slit is irradiated with light.
In a motor control device that obtains a signal for commutation control of the motor based on light passing through a light-transmitting slit, the brushless motor has a number of poles n (n is an integer) and a coil is a three-phase coil. In the above-mentioned motor, two slit rows in which n light-transmitting slits are provided in the code plate are provided, and the light-transmitting slits in each row have a width in the radial direction of the code plate of K ₁ (1 + s
in θ _e ), the slit pitch changes by one cycle for one cycle (K ₁ is a constant, θ _e is an angle where one slit pitch is 360 °), and the translucent slits in the outer row are in the inner row. The phase is shifted by 1/3 pitch with respect to the light-transmitting slit at, and it is arranged at a predetermined reference position,
A first optical sensor that detects the amount of light that has passed through the light-transmitting slits in the outer row, and the amount of light that has been placed at a predetermined reference position and that has passed through the light-transmitting slits in the inner row. Second optical sensor for detecting the
A third optical sensor, which is arranged at a position different in phase by 1/2 pitch and detects the amount of light that has passed through the translucent slits in the outer row, and the phase at a 1/2 pitch from the reference position. A fourth unit which is arranged at a different position and detects the amount of light passing through the light-transmitting slits in the inner row.
K ₂ sin θ _e and K ₂ by determining the difference between the detection signals of the first optical sensor and the third optical sensor and the difference of the detection signals of the second optical sensor and the fourth optical sensor. ₂ sin (θ _e
And a subtracter that generates a signal that is a source of commutation control of + 120 °). (2) A translucent slit is formed on a disc-shaped code plate at a constant pitch along the circumferential direction, the code plate is connected to a rotor of a brushless motor, and the translucent slit is irradiated with light.
In a motor control device that obtains a signal for commutation control of the motor based on light passing through a light-transmitting slit, the brushless motor has a number of poles n (n is an integer) and a coil is a three-phase coil. In the motor, the code plate is provided with one slit row in which n light-transmitting slits are formed, and the light-transmitting slit has a radial width of K ₁ (1 + sin) of the code plate.
θ _e ) (K ₁ is a constant, θ _e is an angle where one pitch of the slit is 360 °) and changes by one cycle for one pitch of the slit, and is arranged at a predetermined reference position. A first optical sensor that detects the amount of light that has passed through the light-transmitting slit, and a light amount of light that has been passed through the light-transmitting slit and are arranged at a position that is out of phase with the reference position by 1/3 pitch. A second optical sensor for detecting
A third optical sensor, which is arranged at a position different in phase from the reference position by ½ pitch and detects the amount of light passing through the translucent slit, and a phase that differs from the reference position by 5/6 pitch. A fourth optical sensor, which is disposed at a different position and detects the amount of light that has passed through the light-transmitting slit, a difference between detection signals of the first optical sensor and the third optical sensor, and the second optical sensor. of obtaining a difference of the optical sensor and the fourth detection signal of the light sensor, K ₁ sinθ _e and K ₁ sin (θ _e +120
And a subtracter that generates a signal that is the basis of commutation control. (3) A transparent slit is formed on a disc-shaped code plate at a constant pitch along the circumferential direction, the code plate is connected to a rotor of a brushless motor, and the transparent slit is irradiated with light.
In a motor control device that obtains a signal for commutation control of the motor based on light passing through a light-transmitting slit, the brushless motor has a number of poles n (n is an integer) and a coil is a three-phase coil. In the above-mentioned motor, two slit rows in which n light-transmitting slits are provided in the code plate are provided, and the light-transmitting slits in each row have a width in the radial direction of the code plate of K ₁ (1 + s).
in θ _e ), the slit pitch changes by one cycle for one cycle (K ₁ is a constant, θ _e is an angle where one slit pitch is 360 °), and the translucent slits in the outer row are in the inner row. The phase is shifted by 1/2 pitch with respect to the light-transmitting slit at, and it is arranged at a predetermined reference position,
A first optical sensor that detects the amount of light that has passed through the light-transmitting slits in the outer row, and the amount of light that has been placed at a predetermined reference position and that has passed through the light-transmitting slits in the inner row. Second optical sensor for detecting the
A third optical sensor which is arranged at a position having a phase difference of / 3 pitch and detects the amount of light that has passed through the light-transmitting slits in the outer row, and a phase which is 1/3 pitch from the reference position. A fourth unit which is arranged at a different position and detects the amount of light passing through the light-transmitting slits in the inner row.
Of the first photosensor and the third photosensor, and the difference of the detection signals of the second photosensor and the fourth photosensor, K ₁ sin θ _e and K _{1 1} sin (θ _e
And a subtracter that generates a signal that is a source of commutation control of + 120 °).

[0007]

According to the present invention, a translucent slit whose width changes according to the sin function is formed on the code plate of the optical encoder, and the brushless motor is commutated based on the detection signal of the light passing through the translucent slit. Control.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 1
FIG. 3 is a diagram showing a configuration example of a code plate used in the motor control device according to the present invention. FIG. 1 illustrates the case of a brushless motor having three poles. In FIG. 1, reference numeral 20 is a disc-shaped code plate. Reference numerals 21 and 22 denote translucent slits, which are formed in two rows at a constant pitch along the circumferential direction of the code plate 20. Since the number of poles of the motor is three, three translucent slits are formed in each row. The width of the translucent slit 21 in the radial direction of the code plate 20 is
The function of K ₁ (1 + sin θ _e ) changes one cycle for one pitch of the slit (K ₁ is a constant, θ _e is an angle at which one pitch of the slit is 360 °). That is, θ _e =
A position P where θ _e = 360 ° from a reference position P _{0 where} 0 °
Between one pitch to _1, the width of the light-transmitting slit 21 is 1
It changes by the period. The width of the translucent slit 22 also changes like the translucent slit 21. However, the phase of the light transmitting slit 22 is shifted from the light transmitting slit 21 by 1/3 pitch. Therefore, the width of the translucent slit 22 is K ₁ {1 + s
in (θ _e + 120 °)}. Reference numerals 23 and 24 denote optical sensors, which are arranged at the reference position P ₀ and detect the light passing through the translucent slits 21 and 22, respectively. Reference numerals 25 and 26 denote optical sensors, and reference positions P ₀ and 1
The light beams are arranged at a position P ₂ having a phase difference of / 2 pitch and detect the light beams passing through the light-transmitting slits 21 and 22, respectively. These photosensors 23 to 26 are, for example, photodiodes, and the magnitude of the detection signal is proportional to the amount of received light.

The number of poles of the brushless motor 1 is not limited to 3 and may be any other number. When the number of poles is n (n is an integer), the number of light transmitting slits formed in the code plate 20 is also n per row. Even if the number of poles changes, the coil of the brushless motor 1 is a three-phase coil.

FIG. 2 is a block diagram of an embodiment of the present invention.
2 that are the same as those in FIGS. 1 and 5 are denoted by the same reference numerals.
In FIG. 2, reference numeral 30 is an optical encoder using the code plate shown in FIG. Although not shown, the optical encoder is provided with a light source similarly to the optical encoder of FIG. Reference numerals 31 to 34 are OP amplifiers for amplifying the detection signals of the optical sensors 23 to 26, respectively, and 35 is an OP amplifier 31.
And a subtractor 36 for taking the difference between the outputs of the OP amplifier 32 and the OP amplifier 32.
It is a subtracter that takes the difference between the outputs of Reference numeral 37 is a low-pass filter (hereinafter referred to as LPF) that extracts a low-frequency component of the output signal of the OP amplifier 34, 38 is a comparator that binarizes the signal extracted by the LPF 37, and 39 is proportional to the frequency of the output of the comparator 38. It is an F / V converter that outputs an analog voltage signal. The output of the F / V converter 39 becomes the speed feedback signal of the motor. Reference numeral 40 is a subtractor that takes a deviation between the speed command value and the value of the speed feedback signal, and 41 is a speed control unit that outputs a control signal for feedback controlling the rotation speed of the motor 1 based on the deviation. The value of this control signal becomes the torque command value of the motor. 42 and 43 are torque command values and subtractors 35 and 36.
A multiplier that multiplies the outputs of to produce a commutation control signal,
44 and 45 are current detection circuits for detecting the currents flowing in the coils of the two phases of the motor 1, and 46 and 47 are multipliers 42.
And 43 and the detection values of the current detection circuits 44 and 45. Reference numerals 48 and 49 are PWM circuits for comparing the signals obtained by the subtractors 46 and 47 with a reference signal of a constant level to obtain a pulse width modulation signal (hereinafter, pulse width modulation is referred to as PWM), and 50 is a transistor element. The motor 1 configured to switch the transistor elements by the PWM signal obtained from the PWM circuits 48 and 49.
Is a drive circuit that supplies an exciting current to the coil. The drive circuit 50 receives only two-phase PWM signals,
Outputs three-phase exciting current. The phase of the other one-phase exciting current is obtained from the following equation. sin θ _e + sin (θ _e + 120 °) + sin (θ _e −120 °) = 0

The operation of the thus configured motor control device will be described. The optical sensors 23 and 24 are arranged at the reference position P ₀ . Further, the phases of the light transmitting slits 21 and 22 are shifted by 1/3 pitch. From this, the detection signals of the optical sensors 23 and 24 passing through the OP amplifiers 31 and 33 are
K ₂ (1 + sin θ _e ) and K ₂ {1 + sin (θ _e respectively)
+ 120 °)}. The optical sensors 25 and 26 are arranged at a position P ₂ which is out of phase with the optical sensors 23 and 24 by 1/2 pitch. From this, the OP amplifier 32
The detection signals of the photosensors 25 and 26 that have passed through and 34 are K ₂ (1-sin θ _e ) and K ₂ {1-sin (θ _e +12), respectively.
0 °)}. The subtractor 35 receives the signal K ₂ (1 + sin
The difference between θ _e ) and K ₂ (1-sin θ _e ) is calculated. Subtractor 36
Is the signal K ₂ {1 + sin (θ _e + 120 °)} and K
₂ Take the difference of {1-sin (θ _e + 120 °)}. As a result, the signals 2K ₂ sin θ _e and 2K ₂ sin (θ _e +12
A two-phase signal required for commutation of 0 °) is obtained. Multiplier 4
2 and 43 multiply the two-phase signal by the torque command value. Based on this multiplication signal, an exciting current is generated by the PWM circuits 48 and 49 and the drive circuit 50, and the motor 1 is commutated.

3 and 4 are views showing another embodiment of the present invention. 3 and 4 are diagrams showing the phase relationship between the light-transmitting slit and the optical sensor. In this figure, the circumferential direction of the code plate is shown expanded in the linear direction.

In FIG. 3, one row of translucent slits 60 is formed. The transparent slit 60 also has the same shape as the transparent slit shown in FIG. P is the pitch of the translucent slits. 61 is an optical sensor arranged at a reference position, and 62, 6
3, 64 has a phase P / P with respect to the optical sensor 61.
The optical sensors are arranged at positions displaced by 3, P / 2 and 5P / 6. 1 + sin θ _e , 1 + sin (θ _e + 120 °) by the optical sensors 61, 62, 63 and 64, respectively.
A signal having a phase of 1-sin θ _e , 1-sin (θ _e + 120 °) is obtained.

In FIG. 4, the transparent slits 70 and 71 are arranged in two rows.
Is formed in. The shape of the translucent slits 70 and 71 is also shown.
It has the same shape as the transparent slit shown in FIG. these
The phase of the translucent slit is shifted by 1/2 pitch.
Numerals 72 and 73 are formed at the reference position and have a light transmitting slit.
Optical sensors for detecting the light passing through 70 and 71, 74 and 7.
5 is the position where the phase is shifted by 1/3 pitch from the reference position.
Light transmitted through the transparent slits 70 and 71
Is an optical sensor that detects Optical sensor 72, 73, 7
4,75 by 1-sin θ_e, 1 + sin
θ_e, 1-sin (θ _e+ 120 °), 1 + sin (θ_e
A signal having a phase of + 120 °) is obtained.

[0015]

According to the present invention, the following effects can be obtained. In the conventional example of FIG. 6, the optical encoder can detect the rotation only with or without the light-transmitting slit, so that the detection signal changes stepwise. Therefore, the detection resolution is poor. On the other hand, according to the present invention, the code plate of the optical encoder is formed with the light-transmitting slit whose width changes according to the sin function. Therefore, the magnitude of the detection signal of the optical encoder continuously changes according to the sin function. Change. Therefore,
The detection resolution is better than that of the conventional example. As a result, the rotation angle of the motor can be detected with high accuracy and commutation control can be performed. In the present invention, since the detection signal of the optical encoder continuously changes according to the sin function, the detection value follows the rotation angle of the motor as compared with the stepwise waveform as in the conventional example. Therefore, the commutation timing delay is reduced, and the commutation can be performed by appropriately capturing the timing at which the motor output torque is maximized. As a result, the output torque of the motor can be maximized.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a code plate used in a motor control device according to the present invention.

FIG. 2 is a configuration diagram showing an embodiment of the present invention.

FIG. 3 is a configuration diagram of another embodiment of the present invention.

FIG. 4 is a configuration diagram of another embodiment of the present invention.

FIG. 5 is a block diagram of a conventional motor control device.

6 is a configuration diagram of a code plate used in the apparatus of FIG.

7 is a waveform diagram of a detection signal of an optical encoder using the code plate of FIG.

[Explanation of symbols]

 1 motor 6,7,8 light source 20 code plate 21,22,60,70,71 translucent slit 23-25,61-64,72-75 optical sensor 35,36 subtractor

Claims (3)

[Claims] 1. A disc-shaped code plate is formed with light-transmitting slits at a constant pitch along a circumferential direction, the code plate is connected to a rotor of a brushless motor, and the light-transmitting slit is irradiated with light. In a motor control device that obtains a signal for commutation control of the motor based on light passing through a light-transmitting slit, the brushless motor has a number of poles n (n is an integer) and a coil is a three-phase coil. In the motor, the code plate is provided with two slit rows in which n light-transmitting slits are provided, and the light-transmitting slits in each row have a width in the radial direction of the code plate of K ₁ (1 + sin θ _e ). The function changes by one cycle for one pitch of the slit (K ₁ is a constant, θ _e is the angle where one pitch of the slit is 360 °), and the translucent slits on the outer row are the translucent slits on the inner row. 1 for slit
The first optical sensor, which is out of phase by / 3 pitch and is arranged at a predetermined reference position, detects the light amount of the light passing through the light-transmitting slits in the outer row, and the predetermined reference position. A second optical sensor that is arranged and detects the light amount of light that has passed through the light-transmitting slits in the inner row; A third optical sensor that detects the amount of light that has passed through the light-transmitting slits in the outer row, and a third optical sensor that is arranged at a position that differs in phase by 1/2 pitch from the reference position and that is in the inner row. A fourth optical sensor that detects the amount of light that has passed through the optical slit, a difference between detection signals of the first optical sensor and the third optical sensor, and a difference between the second optical sensor and the fourth optical sensor. obtains the difference between the detection signals, K ₂ sinθ _e and K ₂ sin ( _e + 120 °)
And a subtractor that generates a signal that is the basis of the commutation control described above. 2. A disc-shaped code plate is formed with light-transmitting slits at a constant pitch along a circumferential direction, the code plate is connected to a rotor of a brushless motor, and the light-transmitting slit is irradiated with light. In a motor control device that obtains a signal for commutation control of the motor based on light passing through a light-transmitting slit, the brushless motor has a number of poles n (n is an integer) and a coil is a three-phase coil. In the motor, the code plate is provided with one slit row in which n light-transmitting slits are formed, and the light-transmitting slit has a width K in the radial direction of the code plate.
₁ (1 + sin θ _e ) function (K ₁ is a constant, θ _e is an angle at which one pitch of the slit is 360 °)
The pitch is changed by one cycle, and is arranged at a predetermined reference position and detects a light amount of the light passing through the translucent slit; and the reference position and 1/3 pitch only. A second optical sensor which is arranged at a position different in phase, detects a light amount of light having passed through the light-transmitting slit, and is arranged at a position different in phase by 1/2 pitch from the reference position, A third optical sensor that detects the amount of light that has passed through the translucent slit, and a light sensor that is disposed at a position having a phase difference of 5/6 pitch from the reference position and that detects the amount of light that has passed through the translucent slit. And a difference between detection signals of the first photosensor and the third photosensor and a difference between detection signals of the second photosensor and the fourth photosensor, and K ₁ sin θ _e and K ₁ sin (θ _e + 120 °)
And a subtractor that generates a signal that is the basis of the commutation control described above. 3. A disc-shaped code plate is formed with light-transmitting slits at a constant pitch along a circumferential direction, the code plate is connected to a rotor of a brushless motor, and the light-transmitting slit is irradiated with light. In a motor control device that obtains a signal for commutation control of the motor based on light passing through a light-transmitting slit, the brushless motor has a number of poles n (n is an integer) and a coil is a three-phase coil. In the motor, the code plate is provided with two slit rows in which n light-transmitting slits are provided, and the light-transmitting slits in each row have a width in the radial direction of the code plate of K ₁ (1 + sin θ _e ). The function changes by one cycle for one pitch of the slit (K ₁ is a constant, θ _e is the angle where one pitch of the slit is 360 °), and the translucent slits on the outer row are the translucent slits on the inner row. 1 for slit
The first optical sensor, which is out of phase with a pitch of / 2, is arranged at a predetermined reference position, and detects the light amount of light that has passed through the light-transmitting slits in the outer row, and a predetermined reference position. A second optical sensor that is arranged and detects the amount of light that has passed through the light-transmitting slits in the inner row; and a second optical sensor that is different in phase from the reference position by 1/3 pitch, A third optical sensor that detects the amount of light that has passed through the light-transmitting slits in the outer row, and a third optical sensor that is arranged at a position having a phase difference of 1/3 pitch from the reference position and that is in the inner row. A fourth optical sensor that detects the amount of light that has passed through the optical slit, a difference between detection signals of the first optical sensor and the third optical sensor, and a difference between the second optical sensor and the fourth optical sensor. obtains the difference between the detection signals, K ₁ sinθ _e and K ₁ sin ( _e + 120 °)
And a subtractor that generates a signal that is the basis of the commutation control described above.