JP2003143891A - Controller for brushless motor and washing machine equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller which achieve higher motor efficiency in a brushless motor than ever. SOLUTION: In the controller for brushless motor, a PWM control circuit 1 comprises: a number-of-revolutions detection circuit 14 which detects the number of revolutions ω of a motor; a position computation circuit 15 which derives a rotational angle θ of the motor; a voltage command control circuit 12 which generates a voltage command signal V* based on a sinusoidal function expressing voltage command signals taking the rotational angle θof the motor, phase advance angle ψ, and voltage amplitude command Va as variables; and a PWM signal generation circuit 13 which generates a PWM signal base on the voltage command signal V*. The voltage command control circuit 12 is provided with a phase advance angle derivation circuit 12a which derives a voltage phase advance angle ψ from the number of revolutions ω of the motor and variation ΔVa in the voltage amplitude command Va.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor control device including an inverter for supplying AC power to a brushless motor and a PWM control circuit for controlling the inverter, and an automatic washing machine including the control device. It is about machines.

[0002]

2. Description of the Related Art In a conventional automatic washing machine, a brushless motor is used as a motor for driving a pulse eater. FIG. 5 shows a configuration example of a brushless motor control device installed in a conventional automatic washing machine. AC power from the commercial power source (4) is once converted into DC power by the rectifier circuit (5) and then converted into AC power by the inverter (6), and the AC power is converted into a brushless motor.
It is supplied to (2) and the motor is driven. In the brushless motor (2), position sensors (3) consisting of Hall elements are arranged at three locations with a phase difference of 120 degrees on the circumference around the rotation axis, and these three position sensors ( 3) (3) Three position signals (H
u, Hv, Hw) is supplied to the PWM control circuit (7), and the inverter (6) is controlled by the PWM control circuit (7).

FIG. 6 shows the configuration of the PWM control circuit (7). The three position signals (Hu, Hv, Hw) obtained from the position sensor are supplied to the position calculation circuit (75) and the rotation speed detection circuit (74). In the rotation speed detection circuit (74), three position signals (Hu, Hv, H
w), the rotation speed ω of the motor is detected, and the result is the phase advance angle derivation circuit that constitutes the voltage command control circuit (72).
(72a) and the position calculation circuit (75). The position calculation circuit (75) calculates the rotation angle θ of the motor based on the three position signals (Hu, Hv, Hw) and the rotation speed ω, and the calculated rotation angle θ is calculated by the voltage command control circuit ( It is supplied to the voltage command signal generation circuit (72b) that composes 72). The phase advance angle deriving circuit (72a) calculates a phase advance angle ψ described later from the rotational speed ω based on the following expression 1.

[0004]

[Formula 1] ψ = K · ω K: constant

The phase advance angle ψ calculated by the phase advance angle deriving circuit (72a) is supplied to the voltage command signal generating circuit (72b). Rotation speed ω obtained from the rotation speed detection circuit (74)
Is supplied to the rotation speed control circuit (71), and in the circuit (71),
The voltage amplitude command Va is created based on the deviation of the motor speed from the target value ω *. The voltage amplitude command Va is supplied to the voltage command signal generation circuit (72b), and in the circuit (72b), the voltage amplitude command V obtained from the rotation speed control circuit (71).
Based on a, the phase advance angle ψ obtained from the phase advance angle deriving circuit (72a), and the rotation angle θ obtained from the position calculation circuit (75), the voltage command signal for the U phase of the brushless motor is calculated from the following equation 2. Vu * is calculated.

[0006]

[Formula 2] Vu * = Va · cos (θ + ψ)

1 for the U-phase voltage command signal Vu *
By giving a phase difference of 20 ° and 240 °, a V phase voltage command signal Vv * and a W phase voltage command signal Vw * are created, and these three phase voltage command signals (Vu *, Vv *, V
w *) is supplied to the PWM signal generation circuit (73), and U
PWM signals for the phase, the V phase, and the W phase are created.

The U-phase, V-phase, and W-phase PWM signals thus created are supplied to the inverter (6) shown in FIG. 5, and the inverter (6) is PWM-controlled. As a result, the brushless motor (2) is driven. Above PW
In the M control circuit (7), as described above, the phase of the voltage command signal is advanced by the phase advance angle ψ so that the phase of the current flowing in the winding matches the phase of the induced voltage generated in the winding. As a result, the motor efficiency is improved.

[0009]

However, the above-mentioned P
The conventional automatic washing machine equipped with the WM control circuit (7) has a problem that a sufficiently high motor efficiency cannot be obtained.
It is an object of the present invention to provide a motor control device which can obtain a higher motor efficiency than ever and an automatic washing machine equipped with the same.

[0010]

Therefore, the applicant has clarified as follows the reason why a sufficiently high motor efficiency cannot be obtained in the conventional automatic washing machine. During the washing operation of the automatic washing machine, the brushless motor is repeatedly rotationally driven forward and backward. FIG. 7 shows a change in the rotation speed of the brushless motor during the washing operation. As shown in the drawing, the brushless motor is accelerated in the positive direction and rotated at a predetermined rotation speed for a predetermined time, and then decelerated. Then, it is accelerated in the negative direction, rotated at a predetermined rotation speed for a fixed time, and then decelerated. In this way, the brushless motor changes in the following manner during the washing operation: accelerated rotation state → constant speed rotation state → deceleration rotation state → acceleration rotation state.

At the time of acceleration rotation, constant speed rotation and deceleration rotation of the brushless motor, the magnitude of the torque to be generated in the motor at that time is different even if the rotation speed ω of the motor is the same. That is, during acceleration rotation, it is necessary to generate a larger torque in the motor than during constant speed rotation, and it is necessary to generate a smaller torque in the motor during deceleration rotation than during constant speed rotation. Here, the phase advance angle to be given to the voltage command signal in order to match the phase of the current flowing in the winding with the phase of the induced voltage generated in the winding depends on the magnitude of the torque to be generated in the brushless motor. FIG. 11 shows the phase advance angle ψ that should be given to the voltage command signal, with the direction of the magnetic flux generated from the permanent magnet of the brushless motor as the d axis and the direction orthogonal to the magnetic flux direction as the q axis. The figure (a) is the phase advance angle ψ when the magnitude of the torque to be generated in the motor is the smallest,
(c) represents the phase advance angle ψ when the magnitude of the torque to be generated in the motor is the largest.

When a voltage V is applied to the motor, a current I flows through the winding to induce a voltage (ω · φ) due to the interlinkage magnetic flux φ, a voltage (R · I) due to the resistance R of the winding, and a winding. A voltage (ω · L · I) is generated in the winding due to the inductance L of the wire. As the amount of torque the motor should generate increases,
As shown in (a), (b), and (c) of the same figure, it is necessary to increase the current component in the q-axis direction that contributes to the generation of torque. When the current component increases, the voltage due to the inductance L of the winding wire increases.
(ω ・ L ・ I) rises. Therefore, the current I flowing in the winding
In order to make the phase of ω coincide with the phase of the induced voltage (ω · φ), it is necessary to increase the phase advance angle ψ. Like this
The phase advance angle ψ to be given to the voltage command signal increases as the magnitude of the torque to be generated in the motor increases.

At the time of constant speed rotation in which the rotation speed of the brushless motor hardly changes, a constant proportional relationship is established between the rotation speed ω of the motor and the phase advance angle ψ to be given to the voltage command signal. Therefore, the conventional phase advance angle derivation circuit (7
2a) has a built-in memory that stores the functional expression expressed by the above mathematical expression 1, and when calculating the phase advance angle ψ,
The functional formula is always used. Therefore, if the rotation speed ω of the brushless motor is the same, the same phase advance angle is always calculated. However, even if the rotational speed ω of the brushless motor is the same, the phase advance angle ψ that should be given to the voltage command signal
Increases as the magnitude of the torque to be generated in the motor increases, as described above. Therefore, when the brushless motor is rotating at a constant speed, an appropriate phase advance angle is obtained according to the magnitude of the torque that should be generated in the motor. A phase advance angle smaller than the phase advance angle corresponding to the magnitude of is obtained. On the other hand, during deceleration rotation, where the torque to be generated is smaller than during constant speed rotation,
A phase advance angle larger than the phase advance angle corresponding to the magnitude of the torque can be obtained.

FIGS. 8 to 10 respectively show a voltage V applied to the motor and a current I flowing through the winding during constant speed rotation, acceleration rotation and deceleration rotation of the brushless motor by the conventional PWM control circuit (7). Represents the phase of. 8 to 10 show the phases of the applied voltage V and the current I when the rotation speed ω of the motor is the same. According to the conventional PWM control circuit (7), as described above, the constant speed rotation is performed. At the same time, the same phase advance angle ψ is given in both acceleration rotation and deceleration rotation. When the brushless motor is rotating at a constant speed, an appropriate phase advance angle ψ is given according to the magnitude of the torque to be generated in the motor. Therefore, as shown in FIG. 8, the phase of the current I flowing in the winding is the induced voltage. A current component in the d-axis direction that does not contribute to torque generation does not occur in agreement with the phase of (ω · φ). On the other hand, during acceleration rotation of the brushless motor, a phase advance angle ψ smaller than an appropriate phase advance angle according to the magnitude of the torque to be generated in the motor is given. Therefore, as shown in FIG. The phase of the current I flowing through the lags behind the induced voltage (ω · φ), and a current component in the d-axis direction that does not contribute to torque generation is generated.
Further, during deceleration rotation of the brushless motor, a phase advance angle ψ larger than an appropriate phase advance angle according to the magnitude of the torque to be generated in the motor is given.
As shown in 0, the phase of the current I flowing in the winding is the induced voltage.
A current component in the d-axis direction that does not contribute to the torque generation is generated in advance of (ω · φ).

As described above, the brushless motor is frequently in the accelerated rotation state and the decelerated rotation state during the washing operation. In the conventional PWM control circuit (7), at the time of such accelerated rotation and decelerated rotation, an appropriate phase advance angle ψ according to the magnitude of the torque to be generated in the motor cannot be obtained, so it does not contribute to the generation of torque. A current component is generated, and a sufficiently high motor efficiency cannot be obtained.

A brushless motor controller according to the present invention comprises an inverter for supplying AC power to the brushless motor, and a PWM control circuit for controlling the inverter. Here, the PWM control circuit includes a speed detection unit that detects a rotation speed of the brushless motor, an angle detection unit that detects a rotation angle of the brushless motor, a rotation angle of the brushless motor, a voltage phase advance angle, and a voltage amplitude command value. And a variable to generate a voltage command signal based on a function representing a change in the voltage command signal, and a PWM signal based on the generated voltage command signal, and the PWM signal is supplied to the inverter. Signal processing means, the arithmetic processing means, the detected rotation speed,
Phase advance angle deriving means for deriving a voltage phase advance angle on the basis of the state quantity representing the fluctuation state of the rotation speed, and the detected rotation angle and the derived voltage phase advance angle on the basis of the function. And a signal generation means for generating a voltage command signal from the voltage amplitude command value.

As described above, during constant speed rotation, acceleration rotation and deceleration rotation of the brushless motor, the magnitude of the torque to be generated by the motor is different even if the rotation speed is the same. That is, even if the rotation speed of the brushless motor is the same, the magnitude of the torque to be generated in the motor is different due to the difference in the fluctuation state of the rotation speed. Further, as described above, as the magnitude of the torque to be generated in the motor increases, the voltage phase advance angle to be given to the voltage command signal increases. Therefore, in the brushless motor control device according to the present invention, when deriving the voltage phase advance angle,
In consideration of the state quantity representing the fluctuation state of the rotation speed of the brushless motor, a larger voltage phase advance angle is derived during acceleration rotation than during constant speed rotation. On the other hand, during decelerated rotation, a smaller voltage phase advance angle is derived than during constant speed rotation. In this way, the phase of the voltage command signal (voltage phase) at the constant speed rotation, the acceleration rotation and the deceleration rotation of the brushless motor is adjusted to an appropriate voltage according to the magnitude of the torque to be generated in the motor. It is possible to advance only the phase advance angle. Therefore, it is possible to match the phase of the current flowing in the winding with the phase of the induced voltage generated in the winding to prevent the generation of a current component that does not contribute to the generation of torque. High motor efficiency can be obtained.

Specifically, the state quantity is a change quantity of the rotation speed of the brushless motor or a change quantity of a value corresponding to the rotation speed, and the phase advance angle deriving means is the rotation speed of the brushless motor. And the relation storing means for storing the relation between the change amount of the rotation speed or the change amount of the value corresponding to the rotation speed and the voltage phase advance angle, and the detection according to the relation stored in the relation storing means. An angle deriving means is provided for deriving the voltage phase advance angle from the rotational speed thus generated and the amount of change in the rotational speed or the amount of change in the value corresponding to the rotational speed.

As the rotation speed of the brushless motor increases, the voltage phase advance angle to be given to the voltage command signal increases. Further, as described above, even if the rotation speed is the same,
The magnitude of the torque to be generated in the motor differs depending on the difference in the fluctuation state of the rotation speed, that is, the change amount of the rotation speed per constant time or the change amount of the value corresponding to the rotation speed.
As the magnitude of the torque increases, the voltage phase advance angle to be given to the voltage command signal increases. Therefore, a constant relationship is established between the rotation speed of the brushless motor, the change amount of the rotation speed or the change amount of the value according to the rotation speed, and the voltage phase advance angle to be given to the voltage command signal. , Such relation can be expressed by a functional expression or a table. Therefore, in the above-described specific configuration, the functional expression or the table expressing the above relationship is stored in the relational expression storage means, and the voltage phase advance angle is derived based on the functional expression or the table.

More specifically, the PWM control circuit is
It comprises a speed control means for deriving a voltage amplitude command value based on a deviation between the detected rotation speed and the target rotation speed, and a value according to the rotation speed is a voltage amplitude command value derived by the speed control means. is there.

In the above specific structure, the voltage amplitude command value for causing the rotational speed of the brushless motor to follow the target rotational speed is derived, and the rotational speed of the brushless motor is controlled. When the brushless motor rotates at a constant speed, the voltage amplitude command value derived by the speed control means hardly changes. On the other hand, during acceleration rotation of the brushless motor, the voltage amplitude command value increases, and during deceleration rotation, the voltage amplitude command value decreases. Therefore, the fluctuation state of the motor rotation speed can be represented by the change amount of the voltage amplitude command value.

More specifically, the relation stored in the relation storing means is proportional to the proportional term proportional to the rotation speed of the brushless motor and the change amount of the rotation speed or the change amount of the voltage amplitude command value. It is a functional expression represented by the sum with the correction term.

At the time of constant speed rotation in which the rotation speed of the brushless motor hardly changes, a constant proportional relationship is established between the rotation speed of the motor and the voltage phase advance angle to be given to the voltage command signal. The voltage phase advance angle can be calculated from the rotation speed of the brushless motor based on Further, during acceleration rotation of the brushless motor, as the magnitude of the torque generated in the motor increases, the amount of increase in the rotation speed per fixed time increases. or,
As the magnitude of the torque increases, the voltage phase advance angle to be given to the voltage command signal increases. Therefore, as the amount of increase in the rotation speed increases, the voltage phase advance angle to be given to the voltage command signal increases. Here, the angle to be increased with respect to the voltage phase advance angle to be given at the time of constant speed rotation is proportional to the increase amount of the rotation speed. On the other hand, at the time of decelerating rotation of the brushless motor, as the magnitude of the torque generated in the motor decreases, the decrease amount of the rotation speed per fixed time increases. Further, as the magnitude of the torque decreases, the voltage phase advance angle to be given to the voltage command signal decreases. Therefore, as the amount of decrease in rotation speed increases, the voltage phase advance angle to be given to the voltage command signal decreases. Here, the angle to be reduced with respect to the voltage phase advance angle to be given at the time of constant speed rotation is proportional to the decrease amount of the rotation speed. Therefore, the functional expression used to calculate the voltage phase advance angle can be expressed by the sum of the proportional term proportional to the rotation speed of the brushless motor and the correction term proportional to the change amount of the rotation speed of the brushless motor.

Further, when the brushless motor is accelerated and rotated, the voltage amplitude command value increases to increase the motor rotation speed, and when the brushless motor is decelerated and rotated, the voltage amplitude command value decreases to decrease the motor rotation speed. Here, the increase amount of the rotation speed increases as the increase amount of the voltage amplitude command value per fixed time increases, and the decrease amount of the rotation speed increases as the decrease amount of the voltage amplitude command value increases. Therefore, the angle to be increased or decreased with respect to the voltage phase advance angle to be given at the time of constant speed rotation is also proportional to the increase or decrease amount of the voltage amplitude command value. Therefore, the functional expression used to calculate the voltage phase advance angle can be expressed by the sum of the proportional term proportional to the rotation speed of the brushless motor and the correction term proportional to the change amount of the voltage amplitude command value.

When the brushless motor rotates at a constant speed, the amount of change in the rotational speed and the amount of change in the voltage amplitude command value are substantially zero. Therefore, the value of the correction term of the functional expression stored in the functional expression storage means becomes substantially zero, and the value obtained by the calculation of the proportional term is calculated as the voltage phase advance angle. In this way, when the brushless motor rotates at a constant speed, a voltage phase advance angle corresponding to the magnitude of the torque to be generated in the motor can be obtained.

When the brushless motor is accelerated and rotated,
Both the change amount of the rotation speed and the change amount of the voltage amplitude command value are represented by positive values. Therefore, the value of the correction term of the functional expression becomes a positive value, and the value obtained by adding the value obtained by the calculation of the correction term to the value obtained by the calculation of the proportional term is calculated as the voltage phase advance angle. In this way, during acceleration rotation of the brushless motor, the voltage phase corresponding to the magnitude of the torque during constant speed rotation is changed by the angle corresponding to the difference between the torque that should be generated during acceleration rotation and the torque that should be generated during constant speed rotation. A voltage phase lead angle larger than the lead angle is obtained.

When the brushless motor is rotating at a reduced speed,
Both the change amount of the rotation speed and the change amount of the voltage amplitude command value are represented by negative values. Therefore, the value of the correction term of the functional expression becomes a negative value, and the value obtained by subtracting the value obtained by the calculation of the correction term from the value obtained by the calculation of the proportional term is calculated as the voltage phase advance angle. In this way, during deceleration rotation of the brushless motor, the voltage phase corresponding to the magnitude of the torque during constant speed rotation is adjusted by an angle corresponding to the difference between the torque that should be generated during constant speed rotation and the torque that should be generated during deceleration rotation. A voltage phase advance angle smaller than the advance angle is obtained.

According to the above-mentioned specific structure, as described above, the voltage suitable for the magnitude of the torque to be generated in the motor is maintained during the constant speed rotation, the acceleration rotation and the deceleration rotation of the brushless motor. The phase advance angle can be obtained. Further, as described above, when the brushless motor rotates at a constant speed,
It is possible to calculate an appropriate voltage phase advance angle using a common functional expression during acceleration rotation and deceleration rotation.

More specifically, the PWM control circuit is
A speed control means for deriving a voltage amplitude command value based on a deviation between the detected rotation speed and a target rotation speed is provided, and the state quantity is a voltage amplitude command value derived by the speed control means and a brushless motor. It is a difference from the voltage amplitude command value when the detected rotation speed is rotating at a constant speed.

When the brushless motor rotates at a constant speed, during acceleration rotation and during deceleration rotation, the voltage amplitude command value derived by the speed control means is different even if the rotation speed is the same. That is, during acceleration rotation, a larger voltage amplitude command value is derived than during constant speed rotation, and during deceleration rotation, a smaller voltage amplitude command value is derived than during constant speed rotation. Further, as the difference between the voltage amplitude command value at the time of acceleration rotation or deceleration rotation and the voltage amplitude command value at the time of constant speed rotation increases, the fluctuation of the rotation speed of the motor increases. Therefore, the fluctuation state of the rotation speed of the motor depends on the difference between the voltage amplitude command value derived by the speed control means and the voltage amplitude command value when the brushless motor is rotating at the constant speed at the time of the derivation. Can be represented.

Further, specifically, the phase advance angle deriving means includes a function formula storing means for storing a function formula having variables of the rotation speed of the brushless motor and the voltage amplitude command value, and the function formula storing means. An angle deriving means is provided for deriving a voltage phase advance angle from the detected rotational speed and the derived voltage amplitude command value based on a stored functional expression.

As described above, the voltage phase advance angle is derived based on the rotation speed of the brushless motor and the state quantity representing the fluctuation state of the rotation speed. Further, the state quantity is the voltage amplitude command value derived by the speed control means as described above,
It can be represented by the difference from the voltage amplitude command value when the brushless motor is rotating at a constant speed at the time of its derivation. Here, when the brushless motor rotates at a constant speed, the relationship between the voltage amplitude command value and the rotation speed of the motor can be approximately represented by a proportional relationship. Therefore, the state quantity can be represented by the rotation speed of the motor and the voltage amplitude command value, and the voltage phase advance angle can be calculated based on the functional expression having the rotation speed of the brushless motor and the voltage amplitude command value as variables. Can be derived.

The automatic washing machine according to the present invention comprises a brushless motor for rotationally driving the pulse eater forward and backward, and a controller for controlling the brushless motor. The controller comprises:
The brushless motor includes an inverter that supplies AC power and a PWM control circuit that controls the inverter. Here, the PWM control circuit includes a speed detection unit that detects a rotation speed of the brushless motor, an angle detection unit that detects a rotation angle of the brushless motor, a rotation angle of the brushless motor, a voltage phase advance angle, and a voltage amplitude command value. Is used as a variable to generate a voltage command signal based on a function representing a change in the voltage command signal, and a PWM signal is generated based on the created voltage command signal.
Signal processing means for supplying the WM signal to the inverter. The arithmetic processing means, based on the detected rotation speed and a state quantity representing a fluctuation state of the rotation speed,
Phase advance angle deriving means for deriving a voltage phase advance angle, and signal creation for creating a voltage command signal from the detected rotation angle, the derived voltage phase advance angle and the voltage amplitude command value based on the function. And means.

During the washing operation of the automatic washing machine, the brushless motor changes in the acceleration rotation state → constant speed rotation state → deceleration rotation state → acceleration rotation state ... In the automatic washing machine according to the present invention, the motor control device of the present invention is configured to control the brushless motor. According to the motor control device, as described above,
It is possible to obtain an appropriate voltage phase advance angle according to the magnitude of the torque to be generated in the motor, whether the brushless motor is rotating at a constant speed, accelerating rotation, or decelerating rotation. Therefore, the phase of the voltage command signal of the brushless motor
By advancing (voltage phase) by an appropriate voltage phase advance angle, the phase of the current flowing in the winding matches the phase of the induced voltage generated in the winding to generate a current component that does not contribute to torque generation. Can be prevented. by this,
It is possible to obtain higher motor efficiency than before, and as a result, power consumption is reduced.

[0035]

According to the controller of the brushless motor and the automatic washing machine including the same according to the present invention, it is possible to obtain a higher motor efficiency than the conventional one.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below based on two examples. First Embodiment An automatic washing machine according to this embodiment includes a brushless motor for driving a pulse eater, and a motor control device that controls the brushless motor. The overall configuration of the motor control device is the same as that of the conventional control device shown in FIG. 5 except for the PWM control circuit, and three position sensors (3) (3) arranged on the circumference of the brushless motor. 3 obtained from (3)
Two position signals (Hu, Hv, Hw) are supplied to the PWM control circuit, and the inverter (6) is controlled by the PWM control circuit.

FIG. 2A shows voltages (Eu, Ev, Ew) induced in the three-phase winding of the brushless motor by the interlinkage magnetic flux φ.
, Each voltage waveform changes sinusoidally with 360 degrees as one cycle, and the three voltage waveforms are 1
It has a phase difference of 20 degrees. Further, FIG. 2B shows three position signals (Hu, H) obtained from three position sensors.
v, Hw). Each position signal is 36
It is a rectangular wave that switches between high and low with 0 degree as one cycle, and the three position signals have a phase difference of 120 degrees with each other.

FIG. 1 shows the configuration of the PWM control circuit (1). The three position signals (Hu, Hv, Hw) obtained from the position sensor are supplied to the position calculation circuit (15) and the rotation speed detection circuit (14). In the rotation speed detection circuit (14), three position signals (Hu, Hv, H
The rotation speed ω of the motor is detected based on w), and the result is the phase advance angle derivation circuit that constitutes the voltage command control circuit (12).
(12a) and the position calculation circuit (15). The position calculation circuit (15) calculates the rotation angle θ of the motor based on the three position signals (Hu, Hv, Hw) and the rotation speed ω, and the calculated rotation angle θ is calculated by the voltage command control circuit ( It is supplied to the voltage command signal generation circuit (12b) which constitutes 12).

Rotational speed ω obtained from the rotational speed detection circuit (14)
Is supplied to the rotation speed control circuit (11), and in the circuit (11),
The voltage amplitude command Va is created based on the deviation of the motor speed from the target value ω *. The rotation speed control circuit (11) has a transfer function C (s), and the voltage amplitude command Va is calculated from the following Expression 3 using the transfer function C (s).

[0040]

[Equation 3] Va = C (s) · (ω * −ω)

Here, the transfer function C (s) is expressed by the following equation 4, for example, and the voltage amplitude command Va is PI controlled.

[0042]

(4) C (s) = Kp + Ki / s Kp, Ki: constant

The voltage amplitude command Va created as described above
Is supplied to the phase advance angle deriving circuit (12a). In the phase advance angle derivation circuit (12a), the rotation speed ω obtained from the rotation speed detection circuit (14) and the change amount of the voltage amplitude command Va obtained from the rotation speed control circuit (11), that is, in the previous calculation cycle Based on the deviation ΔVa from the voltage amplitude command obtained from the rotation speed control circuit (11), the phase advance angle ψ is calculated from the following Expression 5.

[0044]

[Expression 5] ψ = K1 · ω + K2 · ΔVa K1, K2: Positive constant

At the time of constant speed rotation in which the rotation speed ω of the brushless motor hardly changes, a constant proportional relationship is established between the rotation speed ω of the motor and the phase advance angle ψ to be given to the voltage command signal. The phase advance angle ψ can be calculated from the rotational speed ω of the brushless motor based on the proportional relationship. The first term (K1 · ω) of the above equation 5 expresses such a proportional relationship. Here, the constant K1 is obtained experimentally or theoretically in advance.

The rotation speed ω is the same during constant speed rotation in which the rotation speed ω of the brushless motor hardly changes, during acceleration rotation in which the rotation speed ω increases, and during deceleration rotation in which the rotation speed ω decreases. However, the magnitude of the torque to be generated by the motor is different. That is, during acceleration rotation, it is necessary to generate a larger torque in the motor than during constant speed rotation, and during deceleration rotation, it is necessary to generate a smaller torque in the motor than during constant speed rotation. As described above, even if the rotation speed ω of the motor is the same, the magnitude of the torque to be generated in the motor is different due to the difference in the fluctuation state of the rotation speed ω. Further, as the magnitude of the torque to be generated in the motor increases, the phase advance angle ψ to be given to the voltage command signal
Will increase.

During acceleration rotation of the brushless motor, the amount of increase in the number of revolutions ω per fixed time increases as the magnitude of the torque generated in the motor increases. or,
As described above, as the magnitude of the torque to be generated in the motor increases, the phase advance angle ψ to be given to the voltage command signal increases. Therefore, as the amount of increase in the rotation speed ω increases, the phase advance angle ψ to be given to the voltage command signal increases. Here, the angle to be increased with respect to the phase advance angle ψ to be given at the time of constant speed rotation is the rotation speed ω
Proportional to the amount of increase. On the other hand, at the time of decelerating rotation of the brushless motor, as the magnitude of the torque generated in the motor decreases, the reduction amount of the rotation speed ω per constant time increases. Further, as the magnitude of the torque to be generated in the motor decreases, the phase advance angle to be given to the voltage command signal decreases. Therefore, as the reduction amount of the rotation speed ω increases, the phase advance angle to be given to the voltage phase advance angle decreases. Here, the angle to be reduced with respect to the phase advance angle to be given at the time of constant speed rotation is proportional to the reduction amount of the rotation speed ω.

During acceleration rotation of the brushless motor, the rotation speed of the motor increases as the voltage amplitude command Va increases, and during deceleration rotation, the rotation speed of the motor decreases because the voltage amplitude command Va decreases. here,
When the increase amount of the voltage amplitude command Va per fixed time increases, the increase amount of the rotation speed ω increases, and when the decrease amount of the voltage amplitude command Va increases, the decrease amount of the rotation speed ω increases. Therefore, the angle to be increased or decreased with respect to the phase advance angle to be given at the time of constant speed rotation is also proportional to the increase or decrease amount of the voltage amplitude command Va. As described above, a constant proportional relationship is established between the angle to be increased or decreased with respect to the phase advance angle to be given at the time of constant speed rotation and the change amount of the voltage amplitude command Va, and based on the proportional relationship. Thus, the angle to be increased or decreased can be calculated from the change amount of the voltage amplitude command Va. The second term of the above equation 5
(K2 · ΔVa) represents such a proportional relationship. Here, the constant K2 is experimentally or theoretically obtained in advance.

When the brushless motor rotates at a constant speed, the voltage amplitude command V generated by the rotation speed control circuit (11)
a has a substantially constant value. Therefore, the change amount of the voltage amplitude command Va, that is, the deviation ΔVa becomes substantially zero, and the phase advance angle ψ
As a result, the value obtained by the calculation of the first term (K1 · ω) of the above equation 5 is calculated. In this way, when the brushless motor rotates at a constant speed, the phase advance angle ψ corresponding to the magnitude of the torque to be generated in the motor can be obtained.

Further, during acceleration rotation of the brushless motor, the voltage amplitude command Va generated by the rotation speed control circuit (11) increases. Therefore, the deviation ΔV of the voltage amplitude command Va
a becomes a positive value, and the phase advance angle ψ is added to the value obtained by the calculation of the first term (K1ω) of the above-mentioned equation 5 as the second term (K1).
The value obtained by adding the values obtained by the calculation of 2 · ΔVa) is calculated. In this way, during acceleration rotation of the brushless motor, only the angle corresponding to the difference between the torque to be generated during acceleration rotation and the torque during constant speed rotation, the phase advance angle according to the magnitude of torque during constant speed rotation. A larger phase advance angle ψ is obtained.

When the brushless motor is rotating at a reduced speed, the voltage amplitude command Va generated by the rotation speed control circuit (11) is reduced. Therefore, the deviation ΔV of the voltage amplitude command Va
a becomes a negative value, and the phase advance angle ψ is calculated from the value obtained by the calculation of the first term (K1 · ω) of the above-mentioned Equation 5 to the second term
The value obtained by subtracting the value obtained by the calculation of (K2 · ΔVa) is calculated. In this way, during deceleration rotation of the brushless motor, only the angle corresponding to the difference between the torque that should be generated during constant speed rotation and the torque that should be generated during deceleration rotation will cause the phase corresponding to the magnitude of torque during constant speed rotation. A phase advance angle ψ smaller than the advance angle is obtained. In the phase advance angle deriving circuit (12a), as described above, at the constant speed rotation of the brushless motor, at any of the acceleration rotation and the deceleration rotation, an appropriate phase according to the magnitude of the torque to be generated in the motor The advance angle ψ is calculated.

The phase advance angle ψ obtained from the phase advance angle deriving circuit (12a) is supplied to the voltage command signal generating circuit (12b). The voltage amplitude command Va obtained from the rotation speed control circuit (11) as described above is supplied to the voltage command signal generation circuit (12b). In the voltage command signal generation circuit (12b), based on the voltage amplitude command Va, the rotation angle θ supplied from the position calculation circuit (15), and the phase advance angle ψ, the above formula 2
From this, the voltage command signal Vu * for the U phase of the brushless motor is calculated.

1 for the U-phase voltage command signal Vu *
By giving a phase difference of 20 ° and 240 °, a V phase voltage command signal Vv * and a W phase voltage command signal Vw * are created, and these three phase voltage command signals (Vu *, Vv *, V
w *) is supplied to the PWM signal generation circuit (13). PW
In the M signal generation circuit (13), as shown in FIG. 2C, the U-phase voltage command signal Vu * is compared with a predetermined carrier wave (triangular wave), and based on the comparison result, FIG. The U-phase drive signal (PWM signal) shown in is created. Similarly, the V-phase voltage command signal Vv * is compared with a predetermined carrier to create a V-phase drive signal, and the W-phase voltage command signal Vw * is compared with the predetermined carrier to obtain W. A phase drive signal is created.

The U-phase, V-phase, and W-phase PWM signals thus created are supplied to the inverter (6) shown in FIG. 5, and the inverter (6) is PWM-controlled. As a result, the brushless motor (2) is driven.

In the automatic washing machine of the present embodiment, as described above, the phase advance angle ψ is set as the torque to be generated in the motor during the constant speed rotation, the acceleration rotation and the deceleration rotation of the brushless motor. An appropriate value corresponding to the calculated value is calculated. Therefore, the phase of the current flowing through the winding can be matched with the phase of the induced voltage generated in the winding to prevent the generation of a current component that does not contribute to the generation of torque. As a result, it is possible to obtain higher motor efficiency than before, and as a result, power consumption is reduced. In addition, when the brushless motor is rotating at a constant speed, acceleration is rotating, or decelerating is rotating, an appropriate phase advance angle ψ can be calculated by using the functional expression represented by the equation (5).

Second Embodiment The PWM control circuit of the present embodiment has the same structure as the PWM control circuit of the first embodiment shown in FIG. 1 except for the phase advance angle deriving circuit.
It is the same as (1). The phase advance angle derivation circuit of this embodiment is
Based on the rotation speed ω obtained from the rotation speed detection circuit (14) and the voltage amplitude command Va obtained from the rotation speed control circuit (11),
The phase advance angle ψ is calculated from the following Expression 6.

[0057]

[Equation 6] ψ = K2 · (Va + K4 · ω) K2: positive constant, K4: negative constant

When the brushless motor is rotating at a constant speed, during accelerating rotation and during decelerating rotation, the voltage amplitude command Va calculated by the rotation speed control circuit (11) is different even if the rotation speed ω is the same. That is, during acceleration rotation, a larger voltage amplitude command Va is calculated than during constant speed rotation, and during deceleration rotation, a smaller voltage amplitude command Va is calculated than during constant speed rotation. Further, as the difference between the voltage amplitude command value at the time of acceleration rotation or deceleration rotation and the voltage amplitude command value at the time of constant speed rotation increases, the fluctuation of the rotation speed ω of the motor increases. Therefore,
Voltage amplitude command V calculated by the rotation speed control circuit (11)
The fluctuation state of the rotation speed ω of the motor is calculated by subtracting the voltage amplitude command (hereinafter referred to as the reference point pressure amplitude command) Vao when the brushless motor is rotating at a constant speed at the calculation time from a. Can be expressed, and the phase advance angle ψ can be expressed by the following Expression 7.

[0059]

[Formula 7] ψ = K1 · ω + K2 · (Va−Vao) K1, K2: Positive constant

The first term (K1ω) of the equation (7) is the same as the first term of the equation (5) used in the first embodiment, and is the same as the first term of the equation (5). It represents the proportional relationship with the phase advance angle ψ to be given.

During acceleration rotation of the brushless motor, as described above, the angle to be increased with respect to the phase advance angle ψ that should be given during constant speed rotation is proportional to the increase amount of the rotation speed ω. On the other hand, during deceleration rotation of the brushless motor, the angle to be reduced with respect to the phase advance angle to be given during constant speed rotation is proportional to the reduction amount of the rotation speed ω. As described above, as the difference between the voltage amplitude command value at the time of acceleration rotation or deceleration rotation and the voltage amplitude command value at the time of constant speed rotation increases, the fluctuation of the motor rotation speed ω increases. Therefore,
The angle to be increased or decreased with respect to the phase advance angle to be given at the constant speed rotation is determined by the brushless motor from the voltage amplitude command Va calculated by the rotation speed control circuit (11) at the acceleration rotation or the deceleration rotation. It is proportional to the value (Va-Vao) obtained by subtracting the reference point pressure amplitude command Vao when the engine is rotating at a constant speed at the time of calculation. In this way, the angle to be increased or decreased and the subtraction value (Va-Vao) with respect to the phase advance angle to be given at the time of constant speed rotation.
And a certain proportional relationship is established between the two, and the angle to be increased or decreased can be calculated from the subtracted value (Va-Vao) based on the proportional relationship. The second term [K2 · (Va−Vao)] of the above equation 7 represents such a proportional relationship. Here, the constant K2 is experimentally or theoretically obtained in advance.

The reference voltage amplitude command Vao is the magnitude of the q-axis direction component of the current I flowing through the winding, Iq, the inductance of the winding, L, the resistance of the winding, R, and the number of flux linkages of the winding. Let φ be expressed by the following equation 8.

[0063]

(8) Vao = √ {(ω ・ L ・ Iq) ² + (ω ・ φ + R
・ Iq) ² }

When the brushless motor rotates at a high speed, that is, when the rotation speed ω is large, ω · φ becomes a value significantly larger than R · Iq, and R · Iq is set to zero, and the reference voltage command Va is set.
It is possible to calculate o. Therefore, the reference voltage command Va
o is approximately represented by the following Expression 9.

[0065]

[Equation 9] Vao≈K3 · ω K3: Positive constant

Substituting the above equation 9 into the above equation 7, the phase advance angle ψ is expressed by the following equation 10.

[Equation 10] ψ = K1 ・ ω + K2 ・ (Va-K3 ・ ω) = K2 ・ {Va + (K1 / K2-K3) ・ ω}

In the above formula 10, (K1 / K2-K3)
When is replaced with K4, the above equation 6 is obtained. In the phase advance angle deriving circuit of the present embodiment, the phase advance angle ψ is calculated from the above equation 6, and the phase advance angle ψ is supplied to the voltage command signal generation circuit (12b). Voltage command signal generation circuit
At (12b), as described above, the voltage command signal Vu * is calculated based on the voltage amplitude command Va, the rotation angle θ, and the phase advance angle ψ.

In the automatic washing machine of the present embodiment, the phase advance according to the torque to be generated by the motor by the above equation 6 is performed at any of the constant speed rotation, the acceleration rotation and the deceleration rotation of the brushless motor. The angle ψ can be calculated.

The configuration of each part of the present invention is not limited to the above-described embodiment, and various modifications can be made within the technical scope described in the claims. For example, in the first embodiment, the configuration for calculating the phase advance angle ψ from the above equation 5 is adopted, but the present invention is not limited to this, and the rotation speed ω obtained from the rotation speed detection circuit (14) and the rotation speed ω are obtained. The amount of change in ω, that is, the deviation Δω from the rotation speed ω obtained from the rotation speed detection circuit (14) in the previous calculation cycle
It is also possible to adopt a configuration in which the phase advance angle ψ is calculated from the following Expression 11 based on

[0070]

[Expression 11] ψ = K1 · ω + K2 · Δω K1, K2: Positive constant

In the second embodiment, K in the above equation 6
Although a configuration in which 4 is set to a negative constant is adopted, a table representing the relationship between the rotation speed ω and K4 is stored in the internal memory of the phase advance angle deriving circuit, and the value of K4 is set as the rotation speed ω. It is also possible to adopt a configuration that is set accordingly. For example, as shown in FIG. 3, K4 is set so that K4 · ω in the above equation 6 becomes a constant value at the time of high-speed rotation in which the rotation speed ω is a predetermined rotation speed or more, and K4 is set to a negative constant. It is possible to advance the phase of the voltage command signal rather than the configuration.

Further, as shown in FIG. 4, the slope of the straight line representing the relationship between the rotation speed ω and K4 · ω during low speed rotation in which the rotation speed ω is equal to or lower than the predetermined rotation speed is the straight line representing the relationship during high speed rotation. It is possible to delay the phase of the voltage command signal by setting K4 so as to be more gradual than the slope of, and setting K4 to a negative constant. As described above, the reason for delaying the phase of the voltage command signal as compared with the configuration in which K4 is set to a negative constant at low speed rotation is that if K4 is set to a negative constant, R · Iq of the above equation 8 is set at low speed rotation. Since the reference voltage amplitude command Vao is approximately calculated by the above equation 9 as zero, the reference voltage amplitude command Vo applied at low speed rotation
ao becomes a value much smaller than the true value, and
The phase advance angle ψ calculated using is a value significantly larger than the true phase advance angle to be given to the voltage command signal,
This is because the phase of the induced voltage generated in the winding leads the phase of the current flowing in the winding. With such a configuration, it is possible to prevent the generation of a current component that does not contribute to torque generation by making the phase of the current flowing through the winding match the phase of the induced voltage generated in the winding even during low-speed rotation. I can. As a result, higher motor efficiency can be obtained, and as a result, power consumption is further reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a PWM control circuit that constitutes a controller of a brushless motor according to the present invention.

FIG. 2 is a waveform diagram of various signals created in the PWM control circuit.

FIG. 3 is a graph showing the relationship between the rotation speed ω and K4 · ω in another embodiment.

FIG. 4 is a rotational speed ω in another embodiment other than the above embodiment.
5 is a graph showing the relationship between K4 and ω.

FIG. 5 is a block diagram showing an overall configuration of a brushless motor control device.

FIG. 6 is a block diagram showing a configuration of a PWM control circuit that constitutes a conventional brushless motor control device.

FIG. 7 is a graph showing changes in the rotation speed of the brushless motor during the washing operation of the automatic washing machine.

FIG. 8 is a diagram showing phases of a voltage applied to a motor and a current flowing through a winding when the brushless motor rotates at a constant speed.

FIG. 9 is a diagram showing phases of a voltage applied to a motor and a current flowing through a winding when the brushless motor is accelerated and rotated.

FIG. 10 is a diagram showing phases of a voltage applied to a motor and a current flowing through a winding when the brushless motor is rotating at a reduced speed.

FIG. 11 is a diagram showing the relationship between the magnitude of torque to be generated in the brushless motor and the phase advance angle to be given to the voltage command signal.

[Explanation of symbols]

(1) PWM control circuit (2) Brushless motor (3) Position sensor (4) Commercial power supply (5) Rectifier circuit (6) Inverter (11) Speed control circuit (12) Voltage command control circuit (12a) Phase lead angle derivation circuit (12b) Voltage command signal generation circuit (13) PWM signal generation circuit (14) Rotation speed detection circuit (15) Position calculation circuit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3B155 AA01 BB15 HB10 LC15 MA05                       MA08                 5H560 AA10 BB04 DA02 DA19 DB20                       DC01 EB01 SS07 XA04 XA12                       XA13 XA15                 5H576 AA12 BB02 CC01 DD02 DD05                       EE01 EE11 GG02 HB01 LL05                       LL39 LL46

Claims (7)

[Claims] 1. A controller for a brushless motor comprising an inverter for supplying AC power to a brushless motor and a PWM control circuit for controlling the inverter, wherein the PWM control circuit detects a rotation speed of the brushless motor. Speed detection means, angle detection means for detecting the rotation angle of the brushless motor, voltage command based on a function representing the change of the voltage command signal with the rotation angle of the brushless motor, the voltage phase advance angle and the voltage amplitude command value as variables And a signal processing unit that creates a PWM signal based on the created voltage command signal and supplies the PWM signal to an inverter. The arithmetic processing unit is configured to detect the detected signal. A phase advance angle derivative for deriving the voltage phase advance angle based on the rotation speed and the state quantity representing the fluctuation state of the rotation speed. And a signal creating means for creating a voltage command signal from the detected rotation angle, the derived voltage phase advance angle, and the voltage amplitude command value based on the function. Controller for brushless motor. 2. The state quantity is an amount of change in the rotational speed of the brushless motor, or an amount of change in a value corresponding to the rotational speed, and the phase advance angle deriving means includes the rotational speed of the brushless motor, The detected rotation according to the relationship storage means that stores the relationship between the change amount of the rotation speed or the change amount of the value according to the rotation speed and the voltage phase advance angle, and the relationship stored in the relationship storage means. The control device according to claim 1, further comprising: an angle deriving unit that derives a voltage phase advance angle from a speed and a change amount of the rotation speed or a change amount of a value corresponding to the rotation speed. 3. The PWM control circuit includes speed control means for deriving a voltage amplitude command value based on a deviation between the detected rotation speed and a target rotation speed, and the value according to the rotation speed is a speed. The control device according to claim 2, wherein the control device has the voltage amplitude command value derived by the control means. 4. The relationship stored in the relationship storage means includes a proportional term proportional to the rotation speed of the brushless motor,
The control device according to claim 3, wherein the control expression is a functional expression represented by a sum with a correction term proportional to a change amount of the rotation speed or a change amount of the voltage amplitude command value. 5. The PWM control circuit includes speed control means for deriving a voltage amplitude command value based on a deviation between the detected rotation speed and a target rotation speed, and the state quantity is derived by the speed control means. The control device according to claim 1, which is a difference between the voltage amplitude command value and the voltage amplitude command value when the brushless motor is rotating at a constant speed at the detected rotation speed. 6. The phase advance angle deriving means stores a function expression storing means storing a function expression having a rotation speed of the brushless motor and a voltage amplitude command value as variables, and a function stored in the function expression storing means. The control device according to claim 1 or 5, further comprising: an angle deriving unit that derives a voltage phase advance angle from the detected rotation speed and the derived voltage amplitude command value based on an equation. . 7. A brushless motor for rotationally driving a pulse eater in forward and reverse directions, and a control device for controlling the brushless motor, the control device controlling an inverter for supplying AC power to the brushless motor and the inverter. In the automatic washing machine including a PWM control circuit for controlling the rotation speed of the brushless motor, the PWM control circuit detects a rotation speed of the brushless motor, an angle detection means for detecting a rotation angle of the brushless motor, and a rotation of the brushless motor. An arithmetic processing unit that creates a voltage command signal based on a function that represents a change in the voltage command signal using the angle, the voltage phase advance angle, and the voltage amplitude command value as variables, and a PWM signal based on the created voltage command signal. Signal processing means for producing the PWM signal and supplying the PWM signal to an inverter, wherein the arithmetic processing means comprises: Phase advancing angle deriving means for deriving a voltage phase advancing angle based on the rotational speed and a state quantity representing a fluctuation state of the rotational speed, and the detected rotational angle and the derivation based on the function. An automatic washing machine, further comprising: a signal creating unit that creates a voltage command signal from the voltage phase advance angle and the voltage amplitude command value.