KR101451429B1 - Motor, washing machine comprising the motor and method of controlling the washing machine - Google Patents

Abstract

The present invention relates to a motor, a washing machine including the same, and a control method thereof. In the present invention, the linear control of the motor is enabled even in the over-modulation period in which the command voltage exceeds the reference voltage in the space vector control method using the abbreviated operation. According to the motor, the washing machine including the same, and the control method therefor, the motor according to the present invention can be linearly controlled by the space vector control method even in the over-modulation period.

Washing machine, motor, space vector control, and modulation section

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor, a washing machine including the same,

The present invention relates to a motor, and more particularly, to a motor used in a washing machine, a washing machine including the motor, and a control method thereof.

The motor provides rotational force of the rotor by electromagnetic interaction between a stator and a rotor, and is used in a household appliance such as a washing machine. Such a washing machine is a household appliance for washing / drying laundry, and a drum washing machine has recently been released. In the drum type washing machine, a drum in which a washing bag is accommodated is rotatably installed inside a tub in which wash water is stored, and the drum is rotated by the motor to wash / dry the laundry.

Meanwhile, an outer rotor type BLDC motor is used as the motor in the drum washing machine. Such a BLDC motor is driven by abbreviated operation in order to enable relatively high speed rotation relative to the output.

Generally, when the motor reaches the rated speed, the amount of current that can be input to the motor decreases due to the back electromotive force, so that even if a current is applied, the rotational speed of the motor no longer increases. In order to solve such a problem, when the motor reaches the rated speed, the abbreviated operation is performed in the dq axis coordinate system used in the vector control method to calculate the amount of the current input to the d axis parallel to the magnetic flux direction of the permanent magnet Thereby weakening the magnetic flux of the permanent magnet. When the motor is driven by the abbreviated operation, the operation efficiency of the motor is lowered, but the motor can be operated at a speed higher than the rated speed.

On the other hand, the Space Vector Pulse Width Modulation (SVPWM) is a vector vector control method that uses a valid voltage vector of an inverter that applies a current to the motor through switching for controlling three phases, Is a method of synthesizing a vector which is the same as the reference voltage vector given on the average. More specifically, in the space vector control method, six switching vectors, that is, effective voltage vectors that can be realized by six switching elements of the inverter form a hexagon, and when a command voltage vector is given within one PWM cycle, six The effective voltage vector is generated by using the switching moment of six switching elements to generate a voltage equal to the command voltage vector on the average using the two effective voltage vectors and the zero vectors closest to the command voltage vector. According to such a space vector control method, since the DC voltage can be linearly used, the effect of maximizing the applied DC voltage can be expected.

However, the following problems arise in the control of the motor according to the related art.

As described above, in the space vector control method, the reference voltage vector is synthesized using two effective voltage vectors and zero vectors. The reference voltage vector thus synthesized forms a circle substantially in contact with the hexagon formed by the effective voltage vector. Therefore, in the over-modulation period in which the command voltage vector exceeds the circle formed by the reference voltage vector, the linearity of the ratio between the actual voltage and the command voltage is destroyed and linear control of the motor becomes impossible. Therefore, So that it is impossible to precisely control.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor in which linear control of a motor can be performed more efficiently even in an overmodulation period in a space vector control system, And a control method thereof.

According to an aspect of the present invention, there is provided a stator comprising: a stator including a plurality of wound coils; A rotor including a plurality of magnets for generating an electromagnetic interaction with the coil; A speed sensor for sensing a current speed of the rotor; And comparing the current speed and the command speed of the rotor sensed by the speed sensor and comparing the current speed and the command speed of the rotor detected by the speed sensor with a d axis parallel to the magnetic flux direction of the magnet so that the current speed of the rotor follows the command speed, a speed controller for outputting command currents Id * and Iq * coordinate-converted to a current component on a dq synchronous coordinate defined by the q-axis; A current controller for outputting command voltages Vd * and Vq * based on Id * and Iq * output from the speed controller; An inverter for applying power to the coil based on Vd * and Vq * output from the current controller; And the speed controller outputs different values of Id * and Iq * according to the values of Vd * and Vq * output from the current controller.

According to another embodiment of the present invention, the present invention provides a cabinet comprising: a cabinet; A tub provided inside the cabinet and for washing the wash water; A drum rotatably installed in the tub; The motor according to any one of claims 1 to 3, which provides a driving force for rotation of the drum. .

According to another embodiment of the present invention, there is provided a method of controlling a washing machine, comprising the steps of: (a) receiving a control signal of a washing machine to start an operation of the washing machine; (b) initializing the rotor in accordance with the operation signal received by the controller; (c) detecting, by the speed sensor, a rotational speed of the rotor; (d) The speed controller compares the current speed and the command speed of the rotor sensed by the speed sensor, so that the current speed of the rotor is equal to the speed of the d And outputting coordinate-converted command currents Id * and Iq * to a current component on a dq synchronous coordinate defined by an axis and a q-axis orthogonal to a magnetic flux direction of the magnet; (e) the current controller outputs command voltages Vd * and Vq * based on Id * and Iq * output from the speed controller; (f) powering the coils of the stator based on Vd * and Vq * output from the current controller; And (g) when the speed controller outputs Vd * and Vq * output from the current controller so that the value of Iq * is decreased in the negative direction so that the value of Iq * is decreased ; .

According to the motor, the washing machine including the same, and the control method therefor, the motor according to the present invention can be linearly controlled by the space vector control method even in the over-modulation period.

Hereinafter, embodiments of a motor, a washing machine including the same, and a control method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a sectional view showing an embodiment of a washing machine according to the present invention.

Referring to Fig. 1, the cabinet 1 forms an outer appearance of the drum type washing machine. The cabinet 1 may be formed in a hexahedron shape in which a part of a front surface thereof is opened.

Inside the cabinet 1, a tub 3 is provided. The washing water is stored in the tub 3. The tub 3 may be formed in a cylindrical shape having a generally open front surface. The tub 3 is provided with a washing and drinking inlet 4 for the inflow of washing water and a washing water outlet 5 for discharging the washing water.

A drum 7 is installed in the tub 3. The drum (7) is rotatably installed inside the tub (3). The laundry 7 is accommodated in the drum 7. The laundry 7 is washed by the friction between the drum 7 and the laundry cloth or the laundry cloth by the rotation of the drum 7. The drum 7 may also be formed in a cylindrical shape having a front surface corresponding to the tub 3.

The door 9 selectively opens and closes the opened front face of the cabinet 1, the tub 3, and the drum 7. The door (9) can be installed on one side of the cabinet (1) so as to be rotatable about one end thereof.

A damper 11 and a spring 13 are provided between the cabinet 1 and the tub 3 to absorb vibrations generated during the rotation of the drum 7. The damper 11 is positioned between the bottom surface of the cabinet 1 and the bottom surface of the tub 3 and the spring 13 is positioned between the top surface of the cabinet 1 and the top surface of the tub 3 do.

A motor 20 is provided on the rear surface of the tub 3. The motor 20 serves to provide a driving force for rotation of the drum 7. The motor (20) includes a stator (21) and a rotor (23). More specifically, the stator 21 is provided with a plurality of winded coils. The rotor (23) is provided with a plurality of magnets for generating an electromagnetic interaction with the coil. The rotor (23) is provided with a rotating shaft (25) for substantially providing a rotational force to the drum (7). That is, the rotor 23 is rotated by the electromagnetic interaction between the coil and the magnet, and the rotational force of the rotor 23 is transmitted to the drum 7 through the rotating shaft 25.

On the other hand, the motor 20 is provided with a hall sensor 27. The Hall sensor 27 senses the position of the rotor 23. Normally, two Hall sensors 27 are provided on the stator 21. [ The hall sensor 27 generates an ON / OFF signal by the rotation of the rotor 23. [ For example, when the rotor 23 rotates 360 degrees, the hall sensor 27 generates four on / off signals. The position of the rotor 23 is estimated based on the on / off signal generated by the hall sensor 27, thereby controlling the motor 20.

Hereinafter, the operation of the washing machine according to the embodiment of the present invention will be described.

First, the user opens the door (9) and inserts the laundry into the drum (7). Then, the user operates the control panel (not shown) to select the washing cycle of the washing machine. When the washing cycle is started, the motor 20 is rotated, and the amount of the washing cloth is detected by the load detected by the motor 20. And a stroke of the washing machine is performed so as to match the detected laundry amount.

More specifically, when the washing cycle is started, the washing water flows into the tub 3 through the washing and drinking inlet 4 and is stored. When an appropriate amount of wash water is introduced into the tub 3 and stored therein, the motor 20 rotates and the drum 7 is rotated. At this time, the drum 7 rotates in a direction opposite to the forward direction, thereby preventing the laundry from clogging and increasing the washing efficiency.

When it is determined that the washing of the laundry is completed by a predetermined time, the washing water stored in the tub 3 is drained through the washing water outlet 5. Thus, the washing cycle is terminated and the rinsing cycle is started. The rinsing cycle is similar to the above-described washing cycle, and the drum 7 is rotated alternately in the forward and reverse directions to rinse the laundry.

When the rinsing cycle is completed, a dewatering process for removing water from the laundry is performed. In the dehydrating step, the drum 7 is rotated at a high speed to remove water from the laundry. When the predetermined time has elapsed, the dewatering process is terminated and washing of the laundry by the washing machine is completed.

Meanwhile, the motor 20 is driven by abbreviated operation using a vector control method in order to enable high-speed rotation. The vector control method is a kind of power supply control method for controlling the application of the coil current. More specifically, a d-axis coordinate defined by a d-axis parallel to the magnetic flux direction of the magnet and a q-axis perpendicular to the magnet direction of the magnet is set, and current is accurately applied to the d-axis and the q-axis. In the abbreviated operation, the abbreviated operation weakens the magnetic flux of the magnet so that when the command speed of the motor 20 is higher than the rated speed, the magnetic flux direction of the magnet in the dq axis coordinate system The current speed of the rotor 23 is made to follow the command speed.

Next, a control device for motor control in an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing a control device for controlling a motor in an embodiment of the present invention.

2, the control device for controlling the motor 20 includes a motor control unit 30, an SVPWM computing unit 40, an inverter 50, and a current sensing unit 60.

The motor control unit 30 controls the power supplied to the motor 20. More specifically, the motor control unit 30 includes a speed / position detector 31, a speed controller 33, a current controller 35, and a coordinate conversion unit 37. The speed / position detector 31 detects the rotational speed and the rotational position of the motor 20, that is, the rotational speed and the rotational position of the rotor 23 (see FIG. 1). At this time, the speed / position detector 31 detects the rotational speed and position of the rotor 23 by virtue of the position of the rotor 23 sensed by the hall sensor 27 (see FIG. 1) . The speed controller 33 compares the current speed ω of the rotor 23 detected by the speed / position detector 31 with the command speed ω * so that the current speed ω follows the command speed ω * , The d-axis command current Id * and the q-axis command (Iq) are adjusted by adjusting the current components Id and Iq on the dq axis rotation coordinate system defined by the d axis parallel to the magnetic flux direction of the permanent magnet and the q axis perpendicular to the magnetic flux direction of the permanent magnet, Thereby generating a current Iq *, respectively. Based on the command current Id * and the command current Iq * output from the speed controller 33, the current controller 35 performs PID control on the current Id and the current Iq to calculate the d-axis command voltage Vd * and the q-axis command Voltage Vq *, respectively. The coordinate conversion unit 37 converts the rotation coordinate system of d-q axis and the rotation coordinate system of uvw.

The SVPWM operator 40 receives the signal of the uvw stationary coordinate system output from the motor controller 30 and generates an SVPWM signal. The inverter 50 receives the SVPWM signal from the SVPWM operator 40 and directly controls a power input to the motor 20. [ Also, the current sensing unit 60 senses the d-axis current Id and the q-axis current Iq as current currents output from the inverter 50.

First, the speed / position detector 31 continuously estimates and detects the current speed? Of the rotor 23. The current speed? Of the rotor 23 detected by the speed / position detector 31 is input to the speed controller 33. [ The speed controller 33 performs PID control of the current speed of the rotor 23 and the command speed ω * of the rotor to output the d-axis command current Id * and the q-axis command current Iq * of the d-q rotational coordinate system.

At this time, the speed controller 33 adjusts the output values of the command currents Id * and Iq * in accordance with the abrupt speed operation. In the present embodiment, the abrupt speed control is performed when the command speed of the rotor 23 exceeds the rated speed or the command voltages Vd * and Vq * exceed the reference value. More specifically, in the abbreviated operation, the speed controller 33 outputs the command current Id * in the d-axis direction so that the value of the q-axis command current Iq * do. Therefore, abbreviated operation is performed in which the magnetic flux of the magnet is weakened by the command current Iq * in the d-axis direction outputted in the negative direction from the speed controller 33. The speed controller 33 outputs only the command current Iq * in the case of normal operation.

Meanwhile, the command currents Id * and Iq * output from the speed controller 33 are input to the current controller 35. The current controller 35 performs PID control by comparing the command currents Id * and Iq * with the currents Id and Iq of the inverter 50 sensed by the current sensing unit 60 to calculate a command voltage Vd * and Vq *.

The command voltages Vd * and Vq * outputted from the current controller 35 are converted into the command voltage on the uvw stop coordinate system in the coordinate converter 37 and input to the SVPWM operator 40. The SVPWM operator 40 generates an SVPWM signal corresponding to the input command voltages Vd * and Vq * and inputs the SVPWM signal to the inverter 50. The inverter 50 turns on / off six switching elements in response to the input SVPWM signal to drive the motor 20.

Next, abbreviated control according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a space voltage vector diagram for explaining a space vector control method in an embodiment of the present invention.

First, the output phase voltages Va, Vb and Vc output by the six switching elements Sa-Sa ', Sb-Sb' and Sc-Sc 'of the inverter 50 are all 7 Lt; / RTI > Here, the value of the output phase voltage is composed of substantially six effective voltages (V1 to V6) and two zero voltages (V0 and V7). If the six effective voltages are shown on the vector space, they can be expressed as a vector having a phase difference of 60 degrees and a magnitude of 2 / 3Vdc. That is, referring to FIG. 3, a valid voltage vector representing a sixteen effective voltage forms a hexagon.

Switching state Output phase voltage Effective voltage Sa Sb Sc Va Vb Vc 0 0 0 0 0 0 V0 0 0 One -1 / 3Vdc -1 / 3Vdc  2 / 3Vdc V1 0 One 0 -1 / 3Vdc  2 / 3Vdc -1 / 3Vdc V2 0 One One -2 / 3Vdc  1 / 3Vdc  1 / 3Vdc V3 One 0 0  2 / 3Vdc -1 / 3Vdc -1 / 3Vdc V4 One 0 One  1 / 3Vdc -2 / 3Vdc  1 / 3Vdc V5 One One 0  1 / 3Vdc  1 / 3Vdc -2 / 3Vdc V6 One One One 0 0 0 V7

In the space vector control method, the command voltages Vd * and Vq * output from the current controller 35 (see FIG. 2) are set to have the same value as the command voltage vector shown in the vector space, The reference voltage vector is synthesized using the two effective voltage vectors and the zero vectors closest to the command voltage vector. Therefore, when the command voltage vector is located in the over-modulation period (section in FIG. 3) in which the command voltage vector exceeds the reference voltage vector, the ratio of the actual voltage to the command voltage is not linear, So that it is impossible to precisely control. In other words, when the command voltages Vd * and Vq * output from the current controller 35 exceed a reference value corresponding to the reference voltage vector, linear control of the motor 20 is disabled.

In the present embodiment, in the over-modulation period in which the command voltage vector exceeds the reference voltage vector, by controlling the motor 20 by abrupt speed operation, the command in the d axis direction output from the speed controller 33 The value of the current Id * is increased in the negative direction. Therefore, the command voltage vectors of the command voltages Vd * and Vq * output from the current controller 35 are reduced based on the command currents Id * and Iq * output from the speed controller 33 to exceed the reference voltage vector Is located in an area that is not used. Therefore, the linear control of the motor 20 by the space vector control becomes possible.

Hereinafter, a method of controlling a washing machine according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a control flowchart showing a control method of a washing machine according to an embodiment of the present invention.

4, first, the speed / position detector 31 detects the current speed of the rotor 23 (S11). The speed / position detector 31 detects the current speed of the rotor 23 Detection will be accomplished by sensing the position of the rotor 23 by the hall sensor 27.

Next, it is determined whether the command speed of the rotor 23 exceeds the rated speed. (S13) If it is determined in step S13 that the command speed exceeds the rated speed, (S15). If it is determined in S13 that the current speed does not exceed the rated speed, the motor 20 is operated normally (S17)

If it is determined in S15 or S17 that the operation mode of the motor 20 is selected as the abrupt speed operation or the normal operation, the speed controller 33 compares the measured command speed with the rated speed to determine the appropriate command current Id * And Iq * or Iq * (S19). More specifically, when the operation mode of the motor 20 is selected as abbreviated operation, the speed controller 33 outputs an output signal Id * so that the value of Id * is increased in the minus direction so that the value of Iq * do. When the operation mode of the motor 20 is selected as the normal operation, the speed controller 33 outputs only Iq *.

The command current Id * and Iq * or Iq * generated in step S19 are input to the current controller 35. The current controller 35 controls the inverter 50 And outputs the command voltages Vd * and Vq * on the current dq rotating coordinate system (S21).

In step S21, it is determined whether the command voltages Vd * and Vq * exceed a reference value (S23). If it is determined in step S23 that the command voltages Vd * and Vq * exceed the reference value , Steps S15 and S19 are performed.

When it is determined in step S21 that the command voltages Vd * and Vq * do not exceed the reference value, the command voltages Vd * and Vq * output from the current controller 35 are supplied to the coordinate converter 37, The SVPWM computing unit 40 outputs the SVPWM signal corresponding to the command voltage and the SVPWM computing unit 40 computes the SVPWM signal corresponding to the command voltage in the SVPWM computing unit 40, Generates the SVPWM signal and inputs it to the inverter 50. (S25) The inverter 50 drives the motor 20 according to the SVPWM signal received in the step S25 (S27)

 It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents. .

According to the motor, the washing machine including the same, and the control method of the present invention configured as described above, linear control of the motor is enabled in the overmodulation region where the command voltage vector exceeds the reference voltage vector in the space vector control system . Therefore, the effect of using the motor more efficiently can be expected.

1 is a sectional view showing an embodiment of a washing machine according to the present invention;

2 is a block diagram showing a control device for controlling a motor in an embodiment of the present invention.

3 is a space voltage vector diagram for explaining a space vector control method in an embodiment of the present invention.

4 is a control flowchart showing a control method of a washing machine according to an embodiment of the present invention.

Claims (7)

A stator comprising a plurality of wound coils; A rotor including a plurality of magnets for generating an electromagnetic interaction with the coil; A speed sensor for sensing a current speed of the rotor; And comparing the current speed and the command speed of the rotor sensed by the speed sensor and comparing the current speed and the command speed of the rotor detected by the speed sensor with a d axis parallel to the magnetic flux direction of the magnet so that the current speed of the rotor follows the command speed, a speed controller for outputting command currents Id * and Iq * coordinate-converted to a current component on a dq synchronous coordinate defined by the q-axis; A current controller for outputting command voltages Vd * and Vq * based on Id * and Iq * output from the speed controller; An inverter for applying power to the coil based on Vd * and Vq * output from the current controller; Lt; / RTI > The speed controller outputs different values of Id * and Iq * according to the values of Vd * and Vq * output from the current controller, and when Vd * and Vq * output from the current controller exceed the reference value So that the value of Id * is increased in the minus direction so that the value of Iq * is decreased. delete The method according to claim 1, Wherein the speed controller comprises: When the command speed of the rotor is higher than the rated speed of the rotor, the value of Id * is increased so that the value of Iq * is decreased in the negative direction, And outputs Iq * when the command speed of the rotor is faster than the rated speed of the rotor. cabinet; A tub provided inside the cabinet and for washing the wash water; A drum rotatably installed in the tub; And The motor of any one of claims 1 to 3, which provides a driving force for rotation of the drum. . (a) a control section of a washing machine receives an operation signal for starting operation of the washing machine; (b) initializing the rotor in accordance with the operation signal received by the controller; (c) detecting, by the speed sensor, a rotational speed of the rotor; (d) The speed controller compares the current speed and the command speed of the rotor sensed by the speed sensor, so that the current speed of the rotor is equal to the speed of the d And outputting coordinate-converted command currents Id * and Iq * to a current component on a dq synchronous coordinate defined by an axis and a q-axis orthogonal to a magnetic flux direction of the magnet; (e) the current controller outputs command voltages Vd * and Vq * based on Id * and Iq * output from the speed controller; (f) powering the coils of the stator based on Vd * and Vq * output from the current controller; And (g) if the speed controller outputs Vd * and Vq * output from the current controller so that the value of Iq * is decreased in the negative direction so that the value of Iq * is decreased; And a controller for controlling the washing machine. 6. The method of claim 5, In the step (g) Whether or not Vd * and Vq * output from the current controller exceeds the reference value may be determined by determining whether the current rotation speed of the rotor, in which the coil receives the SVPWM signal in the step (f), exceeds the reference rotation speed Thereby determining the washing machine control method. 6. The method of claim 5, In the step (d) Wherein the speed controller comprises: When the command speed of the rotor is higher than the rated speed of the rotor, the value of Id * is increased so that the value of Iq * is decreased in the negative direction, And outputs Iq * when the command speed of the rotor is faster than the rated speed of the rotor.

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