JPH09215377A - Controller of sensorless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the control of the synchronous operation and the smooth rotation of a rotor although the manufacturing cost is low. SOLUTION: A sensorless motor has 3-phase Y-connection motor coils and a rotor with permanent magnets. A voltage induced in the motor coil of one phase by the rotation of the rotor is detected repeatedly in the off-periods of an excitation current and the detected induced voltages are divided into positive voltages and negative voltages with a neutral potential as a zero voltage and integrated and it is judged by the integral value whether the phase of the rotor is advanced or delayed and the excitation timing of the motor coil is adjusted in accordance with the advance and delay of the rotor phase to perform the synchronous rotation of the rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for a sensorless motor such as a brushless motor that does not require a special sensor for detecting the rotational position of a rotor.

[0002]

2. Description of the Related Art A motor having a three-phase Y-connection motor coil and a rotor with a permanent magnet is controlled by an encoder, a hall sensor or the like for detecting the rotational position of the rotor for synchronous operation of the motor. It is generally equipped with a special sensor.

Further, each motor coil has a U → V phase and a W → V phase.
Two-phase excitation is performed by sequentially energizing the coils between the two phases: phase, W phase → U phase, V → U phase, V → W phase, U → W phase.
According to this two-phase excitation, the waveform of the exciting current flowing through each coil becomes a rectangular wave, and it is difficult to obtain a smooth rotation of the rotor. Therefore, in order to make the waveform of the exciting current flowing through each coil close to a sine wave, pulse width modulation control (PWM
Control) is implemented.

[0004]

However, in the above-mentioned prior art, a special sensor such as an encoder is required, and complicated control such as PWM control is required to bring the waveform of the exciting current flowing through each coil close to a sine wave. However, there is a problem that the cost is increased.

[0005]

According to a first aspect of the present invention, in a controller for a sensorless motor including a three-phase Y-connected motor coil and a rotor with a permanent magnet, the motor coil of a certain phase is rotated by the rotation of the rotor. The generated induced voltage is repeatedly detected while the exciting current is OFF, the detected induced voltage is separated into positive and negative with the neutral point potential being zero, and integrated, and the phase advance and delay of the rotor are determined by the integrated value, It is characterized in that the excitation timing of the motor coil is adjusted according to the phase lead and lag of the rotor to perform the synchronous rotation of the rotor.

According to the first aspect of the present invention, the induced voltage generated by the rotation of the rotor is not affected by the exciting current,
Since it can be detected from the motor coil of a certain phase and the synchronous operation control of the motor can be carried out based on this, a special sensor such as an encoder is not required unlike the prior art. Moreover, the induced voltage is positive / negative separated and integrated with the neutral point potential as zero,
Since the phase advance or delay of the rotor is determined based on the integrated value, the influence of noise due to the exciting current flowing through the motor coils of other phases can be reduced, and the determination can be made accurate.

In addition to the structure of the first invention, a second invention of the present application is such that the integrated value indicates the degree of advance or delay of the phase of the rotor, and the adjustment amount of the excitation timing is determined according to the integrated value. It is characterized in that it is configured to.

According to the second aspect of the present invention, since it is possible to judge the degree of phase advance and delay of the rotor from the integrated value, the excitation timing of the motor coil can be adjusted more quickly and appropriately, and a smooth motor can be obtained. Synchronous operation control becomes possible.

A third invention of the present application is the first invention or the second invention.
In addition to the structure of the invention, the excitation of the motor coil is alternately repeated between the two-phase energization and the three-phase energization, and the exciting current flowing in the motor coil of each phase is turned on by 150 ° and turned off by 30 ° every half cycle.
It is characterized in that it is configured to be performed by 2-3 phase excitation.

According to the third aspect of the present invention, the synchronous operation of the motors can be smoothly performed without requiring any special sensor, and the waveform of the exciting current flowing through each coil is simulated by the 2-3 phase excitation. Since it can be a sine wave and the rotor can be smoothly rotated, complicated control for bringing the waveform of the exciting current flowing through each coil close to a sine wave is not required unlike the conventional technology. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a brushless motor drive controller according to an embodiment of the present invention.

The brushless motor 3 has a rotor having permanent magnets magnetized to N and S2 poles and a stator having a motor coil of three-phase Y connection, and excites the motor coil at a predetermined timing. By generating a rotating magnetic field in the stator, the rotor is rotated.

The microprocessor indicated by 1 in FIG. 1 determines the excitation timing of each coil, outputs the excitation timing signals P1 to P6 of the coil based on the determination, fetches the phase information Pa of the rotor obtained from the induced voltage, and controls the speed. Width modulation control (PWM control) for PW, PW based on this
The output of the M signal P13, the detection timing signal P10 for instructing the detection timing of the induced voltage are output, and the speed instruction information P14 is input.

A motor driver shown by 2 in FIG. 1 is provided with six switching elements, which are turned on and off by excitation timing signals P1 to P6 to energize and energize each coil at a predetermined timing, and the stator. For generating a predetermined rotating magnetic field. Excitation of each coil is performed by 2-3 phase excitation described below.

That is, one cycle of 360 degrees is divided into 12 of 30 degrees.
Divide into steps (1) to (12), and perform the energization timing for the U-phase, V-phase, and W-phase coils in each step (1) to (12) as shown in FIG. 2 and FIG. And energization for three phases are performed alternately.

In step (1), the signal P1 (UH) and the signal P5 (VL) are ON, a current flows between the U phase and V phase, the neutral point O is set to zero potential, and the maximum of each coil is set. When the current values are 100% and -100%, the current values flowing in the U-phase coil, the V-phase coil, and the W-phase coil are 75% and -75%, respectively.
0%.

In step (2), the signals P1 (UH), P3 (WH) and P5 (VL) are ON and the two phases of the U phase and the V phase and the two phases of the W phase and the V phase, that is, U phase,
A current flows between the V phase and W phase, and the U phase, V phase, W
The current values flowing in each phase coil are 50% and -100, respectively.
%, 50%.

Also in steps (3) to (12), the ON / OFF timings of the signals P1 to P6 are set as shown in FIGS. 2 and 3, so that the pseudo sine wave current as shown in FIG. 4 is generated. It has a characteristic and its excitation time is 150 every half cycle.
A current flows through the coils of each phase so that the coils are turned on and off by 30 degrees, and the coils of each phase are excited (for PWM control, which will be described later in FIGS. 2 and 4, for simplicity of explanation, this will be changed). Shows what is ignored.).

The microprocessor 1 uses the speed instruction information P
PWM control can be performed in order to perform speed control based on 14. That is, a pulse current is supplied to each coil, and the amount of the supplied current is controlled by changing the duty ratio of the pulse width a with respect to the entire width b shown in FIG. 5 to set the rotation speed of the rotor to the speed instruction value. It is controlled so that they can match. The PWM signal P13 for timing for this is sent from the microprocessor 1 to A
It is output to the ND gate circuit 9. The AND gate circuit 9 has three AND gates, and the PWM signal P13 is input to each of them, and the excitation timing signals P1, P2, and P3 are input to each of them. As a result, the AND gate circuit 9 outputs PWM-controlled excitation timing signals P1, P2, and P3. FIG. 6A shows PWM
Signals P13, (b) are excitation timing signals P1 before input to the AND gate circuit 9, and signals (c) are AND gate circuit 9
The excitation timing signal P1 after the output from each is shown.

Excitation timing signals P4, P5, P6
Is directly input to the corresponding switching element of the motor driver 2, but the excitation timing signals P1, P2, P3
Under the influence of, the current flowing through each coil becomes a PWM-controlled current.

The induced voltage detection circuit indicated by 31 in FIG.
The induced voltage e of the phase coil is detected. The induced voltage circuit 31 includes a sampling hold circuit 7 that repeatedly measures the induced voltage e at a specific timing, and an A / D conversion circuit 5 that converts the measured induced voltage e into 8-bit digital data. .

The induced voltage e of the W-phase coil is induced as shown by the broken line in FIG. 7 as the rotor equipped with the permanent magnet rotates. On the other hand, the value of the current flowing through the W-phase coil is as shown in FIG. 4, which is shown again by the solid line in FIG. This means that the excitation timing of the W-phase coil is determined as shown by the solid line in FIG. 7 in consideration of the induced voltage e.

As shown in FIG. 7, the current flowing through the W-phase coil becomes zero in steps (1) and (7). When the current flowing through the W-phase coil is zero, specifically, the step
Repeatedly measuring the induced voltage e during the period (1),
The output timing of the detection timing signal P10 is determined. It suffices that the detection timing signal P10 be output many times at equal intervals during the period of step (1). Specifically, each pulse generation timing used for PWM control is used. Is rational.

During the step (1), when the phase shift of the rotor is normal, as shown in FIG. 8A, the zero cross point at which the induced voltage e becomes the neutral point potential, that is, zero, It coincides with the reference point S which is the middle point of step (1). On the other hand, when the phase shift of the rotor is advanced, the state becomes as shown in FIG. 8B, and when it is delayed, the state becomes as shown in FIG. 8C.

The induced voltage e measured by the sampling and holding circuit 7 is converted into digital data showing the amount of the voltage by the A / D conversion circuit 5 with positive and negative signs.
The phase information Pa of the rotor is sequentially input to the microprocessor 1. Microprocessor 1 step
The phase information Pa measured during the period of (1) is separated into positive and negative with the neutral point potential being zero and integrated. In the integrated value in the case shown in FIG. 8A, the integrated value on the minus side and the integrated value on the plus side are equal, so the overall integrated value is zero, and as a result, the phase shift of the rotor is determined to be zero. . FIG. 8B
In the case shown in, the integrated value on the plus side is larger than the integrated value on the minus side, so the overall integrated value is positive, and it is determined that the rotor phase is advanced. It is also recognized that the phase shift of the rotor is progressing. On the other hand, in the case of the integrated value shown in FIG. 8C, the integrated value on the minus side is larger than the integrated value on the plus side, so the overall integrated value becomes negative, and it is determined that the rotor phase is delayed. , And its integrated value
The degree to which the phase shift of the rotor is delayed is also recognized.

The microprocessor 1 recognizes the integrated value to adjust the excitation timing of the motor coil. According to the positive amount of specifically when the total integrated value of the positive, toward the small ones to large ones and _{X 1, X 2, X 3} , X 4 divided into four stages, the negative amount if the negative of the absolute value, toward the small ones to large _{ones, -X 1, -X 2, -X} 3, -X 4
And the output timing of the excitation timings P _{1 to} P ₆ is determined as follows.

~ X _{4 The} excitation timing is delayed as much as possible.

The X _{4 to} X ₃ excitation timing is delayed next.

The X _{3 to} X ₂ excitation timing is further delayed.

X _{2 to} X ₁ Excitation timing is delayed to a minimum. X ₁ ~-X ₁ excitation timing without change.

-X ₁ to -X ₂ Advance the excitation timing to the minimum.

-X ₂ to -X _{3 The} excitation timing is advanced to the next.

-X ₃ to -X _{4 The} excitation timing is further advanced.

-X ₄ ~ Maximize the excitation timing.

The operation of this embodiment will be described below.

First, the energization of the coils of the three phases is forcibly started from the stopped state of the motor. The energization method at this time is a so-called full-wave drive method for a three-phase motor, and a current having a duty ratio of 100% is applied to each coil.
Therefore, the PWM signal P13 becomes a signal with a duty ratio of 100%. The excitation of each coil is performed by 2-3 phase excitation. At this time, the rotor rotates synchronously by open loop control in response to this excitation.

At the time of starting, the step time of each step (1) to (12) takes a sufficient time for the motor to start, and gradually shortens the step time to increase the rotation speed of the rotor. , So-called slow-up drive is performed. When the rotation speed of the rotor reaches a sufficient speed, control using the induced voltage detection circuit 31 becomes possible. The rotation speed of the rotor can be known from the timing of the excitation timing signals P1 to P6. Next, the synchronous operation of the motors will be described. When the rotation speed of the rotor reaches a sufficient speed, the energization method is switched from the full-wave driving method to the PWM driving method. At that time, the duty ratio of the pulse width of the PWM signal 13 output from the microprocessor 1 is fixed to 50% (therefore, the PWM control in this case is extremely simple).

By the 2-3 phase excitation by the output of the excitation timing signals P1 to P6 shown in FIG. 2 from the microprocessor 1, the current shown in FIG. 4 is given to each coil and the rotating magnetic field is generated in the stator. The rotor rotates in synchronism with. At this time, how much the rotational phase of the rotor is advanced, how late it is, or whether it is in a normal state is known based on the phase information signal Pa input to the microprocessor 1 as described above. To be When the rotational phase of the rotor is advanced or delayed, the microprocessor 1 outputs the excitation timing signals P1 to P6 so as to synchronize with the phase of the rotor according to the degree as described above. Is output. By correcting the excitation timing in this way,
The synchronous operation of the motors can be carried out quickly.

Next, speed control for rotating the rotor at the commanded rotation speed will be described.

The rotation speed of the rotor is the excitation timing signal P.
It can be known from the timings of 1 to P6, and if the rotation phase of the rotor is in the normal range, it can be confirmed that it represents the actual rotation speed of the rotor. The microprocessor 1 knows the specified rotation speed from the speed instruction information P14 and compares this with the current rotation speed of the rotor.
When the current rotation speed is lower than the specified rotation speed, the output timing of the excitation timing signals P1 to P6 is advanced and the duty ratio of the pulse width of the PWM signal P13 is increased in order to increase the rotation speed of the rotor. Is higher than 50%, and the exciting current flowing through each coil is large. On the other hand, when the current rotation speed is higher than the specified rotation speed, the rotation speed of the rotor is lowered, so that the output timing of the excitation timing signals P1 to P6 is delayed and the pulse width of the PWM signal P13 is increased. Is set to a duty ratio lower than 50%, and the exciting current flowing through each coil is small. Such control is performed in a closed loop to match the rotation speed of the rotor with the specified rotation speed.

The present invention can be constructed in various modes other than the above-mentioned embodiment. For example, in the above embodiment, the speed control is performed by the PWM control method, but the present invention is not limited to this. Further, in the above embodiment, the induced voltage e is repeatedly measured during the step (1), but in addition to this, the induced voltage e may be repeatedly measured during the step (7).

Further, in the above embodiment, the P
Set the duty ratio for the pulse width of the WM signal 13 to 50
It is fixed to%, but the fixed duty ratio is 50%.
However, it is not limited thereto, and may be, for example, 60%, 70%, 80% or the like. Then, by fixing the duty ratio and performing 2-3 phase excitation, as shown in FIG. 4, 0%, ± 50,
%, ± 75%, ± 100% stepwise wave heights were obtained, which were 0%, ± 50%, ± 87%,
An exciting current having a stepwise wave height corresponding to ± 100% and closer to a sine wave may be supplied to each coil. In this case, the PWM control is utilized, and the steps (1), (3), (5), (7), (9), and (11) in FIG.
Set the duty ratio for interphase excitation in steps (2), (4),
Compared to the duty ratio at the time of three-phase excitation in (6), (8), (10), and (12), 87/75 = 116% should be set, and such a PWM signal P13 is output. By exchanging the control contents of the microprocessor 1 as described above, an exciting current closer to a sine wave can be applied to each coil with a relatively simple configuration.

Further, in the above embodiment, the motor coils of each phase are excited by 2-3 phase excitation.
The present invention can be applied to the one that outputs the excitation timing signals P1 to P6 at the excitation timing shown in FIG. 9 by the phase excitation and applies the excitation current to the coils of each phase as shown in FIG. In this case, one cycle of 360 degrees can be divided into six steps (1) to (6) every 60 degrees. For example, in step (1) of these steps, the induced voltage of the W-phase coil is repeated. The detected induced voltage may be positively and negatively separated with the neutral point potential being zero, and integrated, and the phase advance or delay of the rotor may be determined based on the integrated value. Although FIG. 10 shows the case where a rectangular waveform of exciting current is applied to the coils of each phase, these exciting currents may have a waveform approximate to a sine wave by PWM control.

[0044]

According to the first invention of the present application, although the special sensor for detecting the rotational position of the rotor is not required and can be manufactured at low cost, the adverse effect of noise is reduced and the rotational position of the rotor is reduced. Can be accurately detected, and based on this, the synchronous operation of the motors can be smoothly performed.

According to the second invention of the present application, in addition to the effect of the first invention, according to the degree of phase advance and delay of the rotor,
The synchronous operation control of the motor can be performed quickly and appropriately.

According to the third invention of the present application, in addition to the effect of the first invention or the second invention, the waveform of the exciting current flowing through each coil is changed to a pseudo sine wave, though complicated control is not required. Therefore, the rotor can be smoothly rotated.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an excitation timing of each coil in 2-3 phase excitation.

FIG. 3 is a diagram showing a flow of an exciting current of each coil in 2-3 phase excitation.

FIG. 4 is a diagram showing a waveform of an exciting current of each coil in 2-3 phase excitation.

FIG. 5 is a diagram showing a pulse waveform of PWM control.

FIG. 6 is a concrete example of PWM control (a), (b), (c).
Fig.

FIG. 7 is a diagram showing waveforms of an exciting current and an induced voltage of a W-phase coil.

FIG. 8 shows the relationship between the induced voltage and the rotor phase (a),
The figure shown to (b) and (c).

FIG. 9 is a diagram showing the excitation timing of each coil in two-phase excitation.

FIG. 10 is a diagram showing a waveform of an exciting current of each coil in two-phase excitation.

[Explanation of symbols]

 1 Microprocessor 2 Motor driver 3 Motor 31 Induced voltage detection circuit P1 to P6 Excitation timing signal P10 Detection timing signal P13 PWM signal Pa Phase information e Induced voltage

Claims (3)

[Claims] 1. A controller for a sensorless motor comprising a three-phase Y-connected motor coil and a rotor with a permanent magnet, wherein a motor coil of a certain phase generates an induced voltage due to the rotation of the rotor while the exciting current is OFF. Medium-repetitive detection is performed, and the detected induced voltage is separated into positive and negative with the neutral point potential set to zero, and integrated.The integrated value is used to determine the phase advance / delay of the rotor. A controller for a sensorless motor, characterized in that the excitation timing of a coil is adjusted to perform synchronous rotation of a rotor. 2. The sensorless motor according to claim 1, wherein the integrated value indicates the degree of advance or delay of the phase of the rotor, and the adjustment amount of the excitation timing is determined according to the integrated value. Control device. 3. Excitation of a motor coil is carried out by energizing between two phases and
3. The sensorless motor according to claim 1, wherein the phase-to-phase energization is alternately repeated to perform 2-3 phase excitation in which the exciting current flowing through the motor coil of each phase is turned on and turned off by 150 [deg.] Every 30 cycles. Control device.