JP7049623B2 - Washing machine - Google Patents

Description

The present invention relates to a washing machine provided with a permanent magnet synchronous motor, which can appropriately start the motor.

This type of washing machine is configured to include a pulsator that agitates the laundry, a permanent magnet synchronous motor that drives the pulsator, and a sensorless control means for starting and stopping the motor with respect to the rotor. Is customary.

By the way, if the rotor position of the permanent magnet synchronous motor is unknown when the motor is started, the start may fail.

As means for solving a motor start failure, for example, those shown in Patent Documents 1 and 2 are disclosed.

Patent Document 1 describes the position detection means by shifting to sensorless control in which the rotor position detection means using a position sensor is used for stable rotation at the time of start-up or low speed rotation in which the load fluctuation is large, and the rotor position detection means is not used at the time of high speed rotation. Disclosed is a technique for reducing current distortion caused by variations in noise and reducing noise.

Further, Patent Document 2 includes a rotor position detection circuit based on induced voltage detection. It is configured to detect the induced voltage during the commutation period after the rotor is fixed at the time of start-up, thereby appropriately adjusting the energization pattern, increase the motor output torque at the time of start-up, and start up at high speed and stably. ..

Japanese Unexamined Patent Publication No. 2007-175135

JP-A-2002-252996

However, all of them require some kind of position detecting means to detect the position of the rotor, which causes a problem of cost increase.

On the other hand, in order to properly start the motor by sensorless control that does not use the rotor position detecting means, in order to position the rotor, an appropriate current is passed through the three-phase winding to make the rotor magnetic in the appropriate direction. It is necessary to attract the rotor to the stator and start the synchronous rotation of the rotor by using the rotating magnetic field generated with the stator.

To this end, the following issues must be resolved. In principle, the position of the rotor when stopped is not known by sensorless control, so if the rotor is attracted in an inappropriate direction, a large backtracking or forward rotation of the rotor may occur, and the rotor may vibrate for a short period of time.

FIG. 13 shows an example thereof, and it is assumed that the rotor R constituting the permanent magnet synchronous motor M is stopped at the phase (a). In that state, when the currents Iu, Iv, and Iw as shown in the figure are passed, a magnetic pole appears on the stator side, and the rotor R is rotated by about 90 ° due to the attractive force and repulsive force of the magnet of the rotor R to be in the state of (b). Move. If the rotor R shifts to synchronous rotation during rotation or vibration, the rotor R cannot smoothly rotate synchronously with respect to the rotating magnetic field generated between the rotor R and the stator, and step-out may occur.

If the positioning time of the rotor R is lengthened, such a problem is less likely to occur, but in the washing machine, the pulsator must be quickly inverted in order to obtain the cleaning power, so that the positioning time cannot be set long. ..

The present invention has been made by paying attention to such a problem, and by estimating the phase of the rotor when the motor is stopped and estimating the position of the rotor, it is smooth without using a separate rotor position detecting means. The purpose is to realize control that starts the motor at the same synchronous rotation and shifts to sensorless control.

The present invention has taken the following measures in order to achieve such an object.

The washing machine of the present invention includes a pulsator that agitates the laundry, a permanent magnet synchronous motor that drives the pulsator forward and reverse, and a control means that controls the start and stop of the motor with respect to the rotor without a sensor. The control means are a short-circuit brake control unit that performs a short-circuit brake when the rotor is stopped from a state of rotating in a predetermined rotation direction, and a phase current flowing through the winding due to the short-circuit brake is predetermined as a phase current value immediately before the rotor is stopped. It is provided with a stop phase estimation unit that estimates the phase in which the rotor has stopped from the phase current detected when the value falls below a predetermined value, and a storage unit that stores the estimated stop phase. When the rotor is rotated and started in the direction opposite to the rotation direction, the stop phase of the rotor estimated from the storage unit is taken out, and based on this, a positioning current vector, which is a current vector for positioning the rotor at the start of synchronous rotation, is generated. It is a feature.

In this case, in the stop phase estimation unit, the short-circuit brake current vector, which is the vector of the phase current flowing through the winding due to the short-circuit brake, is immediately before the stop for a plurality of sectors on the static coordinates classified by the magnitude relationship of the phase current. It is desirable to determine which sector it belongs to.

In particular, the stop phase estimation unit sets the central phase angle of the determined sector as the phase angle of the short-circuit brake current vector existing in the vicinity of the q-axis of the rotational coordinate system, and adds or subtracts a predetermined angle to this phase angle to obtain the phase angle of the d-axis. It is desirable to estimate.

Alternatively, the stop phase estimation unit sets the angle obtained by adding the correction angle derived from the correspondence relationship determined in advance based on the phase current to the reference phase angle of the estimated sector as the phase angle of the short-circuit brake current vector existing in the vicinity of the q-axis. It is desirable to estimate the phase angle of the d-axis by adding or subtracting a predetermined angle to this phase angle.

According to the present invention, in the inversion operation of the pulsator, the rotor phase at the time of stopping can be estimated by the stop phase estimation unit, and the estimated phase can be stored in the storage unit. Therefore, since the position of the rotor can be known to some extent by calling the phase of the rotor from the storage unit, it is not necessary to separately provide a detection means for detecting the position of the rotor, and the product cost can be reduced. Further, by calling the phase of the rotor, the rotor can be reliably positioned and the rotor positioning time can be shortened, so that the motor power consumption for each inversion can be reduced.

Further, according to the present invention, since it is determined which sector the short-circuit brake current vector belongs to based on the magnitude relationship of the phase current, the direction of the short-circuit brake current vector can be easily grasped.

Further, according to the present invention, since the central phase angle of the determined sector is set as the phase angle of the q-axis of the rotating coordinate system, the phase angle of the d-axis can be estimated without any special calculation.

Further, according to the present invention, the phase angle of the q-axis is an angle obtained by adding a correction angle derived from a predetermined correspondence relationship based on the phase current to the estimated reference phase angle of the sector, so that a relatively simple calculation is performed. It is possible to estimate the phase angle of the d-axis with higher accuracy.

Further, according to the present invention, since the phase of the rotor is taken out from the storage unit and the positioning current vector at the start of synchronous rotation is generated, it is possible to appropriately prevent the rotor from retreating, leading rotation and vibration at the start of synchronous rotation. can.

The perspective view which shows the appearance of the washing machine which concerns on 1st Embodiment of this invention. A vertical sectional view showing a schematic configuration of a washing machine. The circuit diagram which shows the system configuration of the motor control system which is the precondition configuration of the phase estimation by the short circuit brake in this embodiment. A block diagram showing a phase estimation by a short-circuit brake and a function of starting by the phase estimation in the system according to the present embodiment. The figure which shows the relationship between a positioning current vector and a rest coordinate system. The figure which shows the vector locus of the short circuit brake current vector from applying a short circuit brake to stopping a rotor. The figure which shows the relationship between the dq coordinate just before stop and the short circuit brake current vector. The figure which shows the relationship between a short-circuit brake current vector and d-axis. The figure which shows the relationship between the magnitude and phase of a short circuit brake current vector. The flowchart which shows the processing procedure of the phase estimation which concerns on this embodiment. The flowchart which shows a part of the processing procedure of phase estimation which concerns on 2nd Embodiment of this invention. The figure which shows the structure of the short circuit brake control part which concerns on the modification of this invention. The figure which shows the relationship between the rotor phase at the time of synchronous rotation start and the occurrence of a defect.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a perspective view showing the appearance of a vertical washing machine (hereinafter referred to as “washing machine”) 1 according to an embodiment of the present invention. Further, FIG. 2 is a vertical sectional view showing a schematic configuration of the washing machine 1 of the present embodiment.

The washing machine 1 includes a washing machine main body 11, an outer tub 12, a dehydration tub (washing tub) 13, an input unit 14, a pulsator (stirring blade) 15, a drive unit 16, and a control means C (FIG. 3). See) and. Such a washing machine 1 automatically determines the amount of laundry in the dehydration tub 13 as a load amount when a start key (not shown), which is in the input unit 14 and performs washing fully automatically, is pressed, and uses the load amount as the load amount. Based on this, the amount of water stored in the outer tub 12 is automatically determined in the washing step and the rinsing step, and the washing operation is performed by driving the pulsator 15 in the forward and reverse directions.

The washing machine main body 11 has a substantially rectangular parallelepiped shape, and has an opening 11b for taking in and out laundry (clothes) to and from the dehydration tub 13 and an opening / closing lid 11c that can open and close the opening 11b on the upper surface 11a. By opening the opening / closing lid 11c, the laundry can be taken in and out of the dehydration tub 13 through the opening 11b. Further, the above-mentioned input portion 14 is formed on the upper surface 11a of such a washing machine main body 11.

The outer tub 12 shown in FIG. 2 is a bottomed cylindrical member that can store water and is arranged inside the washing machine main body 11.

The dehydration tub 13 as a washing tub is a bottomed cylindrical member that is arranged coaxially with the outer tub 12 inside the outer tub 12 and is rotatably supported by the outer tub 12. The dehydration tank 13 has a smaller diameter than the outer tank 12, and has a large number of water passage holes (not shown) on the wall surface 13a thereof.

The pulsator 15 is rotatably arranged in the center of the bottom 13b of the dehydration tank 13 and agitates the water stored in the outer tank 12 to generate a water flow.

The drive unit 16 includes a motor M and a clutch 16b. The motor M of this embodiment uses what is called a permanent magnet type synchronous motor (so-called "PM motor"). The motor M rotates the dehydration tank 13 by rotating the drive shaft m extending toward the bottom 13a of the dehydration tank 13. Further, the motor M can apply torque to the pulsator 15 by switching the clutch 16b to rotate the pulsator 15. Therefore, in the washing process and the rinsing process, the washing machine 1 mainly rotates only the pulsator 15 in the forward and reverse directions through a predetermined rotation ON period and rotation OFF period, and in the dehydration process, the dehydration tub 13 and the pulsator 15 are integrally rotated at high speed. It can be rotated in one direction. The rotation speed of the pulsator 5 at the time of forward / reverse rotation is set to, for example, 900 rpm.

As described above, in order to properly start the rotor R after stopping without a sensor, an appropriate current is passed through the three-phase winding to attract the rotor R in an appropriate direction with a magnetic force, and synchronous rotation is smoothly started. There is a need.

Therefore, in the present embodiment, as shown in FIG. 4, the control means C includes a short-circuit brake control unit 61 that performs a short-circuit brake at the time of stop, and a phase current flowing through the winding due to the short-circuit brake when the phase current immediately before the stop is stopped. The stop phase estimation unit 7 for estimating the phase of the rotor R of the rotor R and the storage unit 8 for storing the estimated phase of the rotor R at the time of stop are included, and the stop phase of the rotor R estimated from the storage unit 8 at the time of startup is included. Is taken out, and based on this, a current vector V1 (hereinafter, referred to as “positioning current vector”) for positioning the rotor R at the start of synchronous rotation is generated.

With this configuration, in the reversing operation of the pulsator 15, the phase of the rotor R at the time of stopping can be estimated and stored in the storage unit 8 without using a separate rotor position detecting device. Therefore, by using the stored phase of the rotor, it is possible to reliably position the rotor R at the start of synchronous rotation. The rotor R can be reliably started. In addition, the rotor positioning time can be shortened, and the motor power consumption for each inversion can be reduced.

Here, the short-circuit brake is a brake in which the U / V / W winding is short-circuited by a switching element such as an IGBT, and the rotational energy is converted into Joule heat of the motor winding.

Hereinafter, first, the configuration of the control means C that performs sensorless control will be described. When starting from the motor stop, if the rotor is stopped or the speed is extremely low, the induced voltage of the motor M is too small, so that sensorless vector control is impossible. Therefore, as shown in FIG. 4, the motor drive control unit 6 of the control means C is forced to rotate the rotor R to a certain speed by the synchronous rotation in the synchronous rotation control unit 62, and then the sensorless vector control is performed. The unit 63 is configured to shift to vector control.

As shown in FIG. 3, the control means C has a torque command generation unit 2 that generates a torque command based on a deviation between the motor rotation speed command value ω ^* _m given as a control amount and the motor rotation speed estimated value ω _m . , The deviation between the motor current Iq (Id) during driving and the current command value Iq ^* (Id ^* ) corresponding to the torque command value T ^* is converted into the motor voltage command values V ^* q and V ^* d to convert the motor M. Speed estimation as a speed estimation unit that estimates the motor rotation speed ω _m using the motor drive control unit 3 to be driven and the motor voltages Vq and Vd related to the motor currents Iq and Id and the motor voltage command values V ^* q and V ^* d. A device 4 is provided, and the speed estimator 4 is configured in a control loop 5. The torque command generation unit 2 and the motor drive control unit 3 are generally referred to as components of an inverter controller. Further, here, it is treated as assuming that the motor voltages Vq and Vd equal to the motor voltage command values V ^* q and V ^* d are generated.

In the torque command generation unit 2, first, the rotation speed command ω ^* m given from the microcomputer or the like that controls the overall operation of the washing machine 1 and the estimated speed value ω _m estimated from the motor driving state are input to the subtractor 21. The difference output of the subtractor 21 is input to the speed controller 22.

The speed controller 22 generates a torque command T ^* by PI control based on the difference amount between the rotation speed command ω ^* _m and the estimated speed ω _m in order to control the rotation speed of the motor M to the target value.

The torque command T ^* generated by the torque command generation unit 22 is input to the motor drive control unit 3.

The motor drive control unit 3 performs voltage drive while switching the switches SW1 and SW2 under the rotating coordinate system (d, q) of the magnetic poles rotating with the rotation of the rotor R of the synchronous motor M.

The switch SW2 is connected to the _B side during sensorless vector control, and the torque command value T ^* is multiplied by the torque coefficient 1 / KE in the gain multiplication unit 31 to obtain the q-axis current command value Iq ^* , which is subtracted. It is input to the q-axis current controller 33 via the device 32. At the time of synchronous rotation, the switch SW2 is connected to the A side and Iq ^* = 0. The switch SW1 is connected to the B side during sensorless vector control, and the command value Id ^* = 0 is output from the d-axis current command unit 34 and input to the d-axis current controller 36 via the subtractor 35. .. At the time of synchronous rotation, the switch SW1 is connected to the A side and Id ^* = a predetermined current value, for example, 3 [A]. The q-axis current value Iq output from the second converter 51 described later, which performs [uvw → dq] conversion, is given to the subtractor 32 as a subtraction value, and the subtractor 35 is given the second value. The d-axis current value Iq output from the converter 51 is given as a subtraction value.

The q-axis current controller 33 generates the q-axis voltage command value Vq ^* by performing PI control based on the difference between the q-axis current command value Iq ^* and the q-axis current value Iq. The d-axis current controller 36 generates a d-axis voltage command value Vd ^* by performing PI control based on the difference between the d-axis current command value Id ^* and the q-axis current value Iq. Then, it is input to the first converter 37 that performs [dq → uvv] conversion in order to convert it into a three-phase voltage command.

Whether to perform voltage drive control or short-circuit brake control is switched by switches SW4 and SW5. The switch SW4 is normally connected to the d-axis voltage command value Vd ^* side (AB side), but when the rotor R is stopped, it is switched to the short-circuit brake command Vd = 0 side (C side) by the short-circuit brake control. The switch SW5 is normally connected to the q-axis voltage command value Vq ^* side (AB side), but when the rotor R is stopped, it is switched to the short-circuit brake command Vq = 0 side (C side) by the short-circuit brake control.

Given the estimated rotor rotation phase angle θe, the first converter 37 sets q, d voltage command values Vq ^* and Vd ^* to the three-phase voltage command values Vu, Vv, Vw based on the estimated rotor rotation phase angle θe. Is converted to, and the motor M is energized via the motor excitation circuit 38.

On the other hand, the control loop 5 detects the phase currents Iu, Iv, and Iw through the phase current detection unit 50 provided in the motor excitation circuit 38, and performs the second conversion to perform [uvv → dq] conversion. Input to the device 51. The second converter 51 converts the phase current value into q and d-axis current values Id and Iq by being given the estimated rotor rotation phase angle θe. These q and d-axis current values are input to the subtractors 35 and 32, respectively.

The estimated value of the rotor phase is switched by the switch SW3. This switch SW3 is connected to the B side during sensorless vector control, detects the motor current / voltage, and estimates the motor speed with the speed estimator 4. It is integrated to obtain the rotor phase θ. On the other hand, at the time of synchronous rotation at the initial stage of activation, the switch SW3 is connected to the A side, and the integral value of the axial velocity command ω ^* _m is added to the integral initial value of the storage unit 8 to create a phase θ, and the phase θ is created by the θ created here. Synchronous rotation is forcibly performed. The initial phase is the initial value of integration.

The speed estimator 4 is a generally known one including a rotor phase error estimator (not shown) and a PLL (Phase Locked Loop) controller.

Based on the above configuration, the algorithms for phase estimation and application when the rotor is stopped / restarted will be described.
If the positioning current vector V1 can be arranged in the vicinity of the d-axis of the rotating coordinate system, the back / forward rotation of the rotor R at the time of starting hardly occurs. That is, assuming that the positioning current vector V1 is appropriately set in a phase distant from the d-axis as shown in FIG. 5 (a), torque is generated by the q-axis current component Iq as shown in FIG. 5 (b). Will occur, and the dq axis of the rotor R will start to rotate. As shown in FIG. 5C, the rotation convergence position has a phase very close to the d-axis.

Therefore, as shown in FIG. 5C from the beginning, if the positioning current vector V1 can be arranged near the q-axis, it is possible to prevent torque in the rotation direction from being generated, so that the rotor R does not rotate during positioning. , Can enter synchronous rotation.

Therefore, in the present embodiment, the stop phase estimation unit 7 shown in FIG. 4 is made to estimate the d-axis phase angle θ ₀ , which is the stop phase of the rotor R. The stop phase estimation unit 7 includes a stop immediately before stop detection unit 71, a UVW comparison unit 72, and a phase determination unit 73. Immediately before stopping, the detection unit 71 monitors the phase current and detects whether or not the phase current has reached a predetermined current value as the phase current value immediately before stopping the rotor R. The UVW comparison unit 72 is a vector of the phase current flowing through the winding by the short-circuit brake for a plurality of sectors 1 to 6 on the static coordinates (α, β) classified by the magnitude relationship of the phase current (hereinafter, “short-circuit”). The determination of which sector the brake current vector V2 ”belongs to immediately before the stop, that is, at the time when the detection unit 71 immediately before the stop detects a predetermined current value is compared by the magnitude relation of Iu, Iv, and Iw. The phase determination unit 73 determines the stop phase based on the comparison result of the UVW comparison unit 72.

In this way, the direction of the short-circuit brake current vector V2 can be easily grasped by determining which sector the short-circuit brake current vector V2 belongs to based on the magnitude relationship of the phase currents.

Hereinafter, the algorithm for estimating the d-axis phase angle immediately before the rotor R is stopped for that purpose will be described. Here, the explanation will proceed with the electric angular velocity as ω _2n .

である。 The voltage equation for permanent magnet synchronous motors is based on the general PM motor model.

Is.

Since the short-circuit brake is in the motor winding short-circuit state, that is, the state in which the motor applied voltage is 0,

At the time of short-circuit braking, it is considered that the dq current does not change suddenly, so the differential term (p term) also becomes 0.

From here, the following Iq and Id are obtained.

That is, it can be seen that Id and Iq change depending on the rotation speed ω _2n at the time of short-circuit braking.

From the above equation, FIG. 6 shows the current vector locus when the rotation speed changes from ± 900 [rpm] to 0 [rpm] by the short-circuit brake. However, the calculation is performed with R = 2.2 [Ω], Ld = 25 [mH], Lq = 28 [mH], Φ = 0.174 [Wb], and P _pn = 8.

When the rotor R is rotating forward, that is, counterclockwise, the short-circuit brake current vector V2 at a high rotation speed of 900 [rpm] is located near the d-axis of the third quadrant. On the other hand, the short-circuit brake current vector V2 turns counterclockwise while reducing the norm as the rotation speed decreases, and reaches the origin when the motor M is stopped. Therefore, it is considered that the short-circuit brake current vector V2 immediately before the motor M is stopped is located near the negative side of the q-axis.

When the rotor R is rotating in the reverse direction, that is, clockwise, the short-circuit brake current vector V2 when the rotation speed is high speed 900 [rpm] is a vector vertically symmetrical to the above from the position near the d-axis in the third quadrant. Draw a trajectory and approach the origin clockwise. It is considered that the short-circuit brake current vector V2 immediately before the motor M is stopped is located near the positive side of the q-axis.

Since the motor torque is proportional to Iq, torque in the direction opposite to the rotation direction, that is, braking torque is generated.

FIG. 7 shows the α-β stationary coordinates and the dq rotation coordinates, and the short-circuit brake current vector V2 immediately before the stop is shown there. The short-circuit brake current vector V2 at the time of forward rotation exists in the third quadrant of the dq coordinate system. As the short-circuit brake current vector V2 decreases as ω _2n decreases, the length of the vector becomes shorter and gradually approaches the negative side of the q-axis. When the position immediately before the stop is shown in FIG. 7A, the short-circuit brake current vector V2 belongs to the fourth quadrant, sector 5.

Further, in the negative rotation, the dq seat table rotates at −ω _2n , and the short-circuit brake current vector V2 exists in the second quadrant of the dq coordinate. As the short-circuit brake current vector V2 decreases as ω _2n decreases, the length of the vector becomes shorter and gradually approaches the positive side of the q-axis. In the case of FIG. 7B, the short-circuit brake current vector V2 belongs to the second quadrant, sector 3.

The sector in which the short-circuit brake current vector V2 ends can be determined by examining the magnitude relationship between the currents Iu, Iv, and Iw of each phase from Table 1. The UVW comparison unit 72 extracts the amplitude values of Iu, Iv, and Iw, compares the large-medium-small relations, and determines in which sector the short-circuit brake current vector V2 exists from the result.

As shown in FIG. 8, the position rotated clockwise from 90 ° to 100 ° is the position on the d-axis. First, the phase determination unit 73 holds the data in Table 1, determines the sector center phase angle θ _M from the sector determined by the UVW comparison unit 72, and sets the phase angle θ ^∧ of the short-circuit brake current vector V2.

By setting the central phase angle θ ^∧ of the determined sector to the phase angle θ ^∧ of the short-circuit brake current vector V2 in this way, the phase angle of the d-axis can be estimated without any special calculation.

However, if the rotor R is completely stopped, the phase current of the short-circuit brake becomes 0, which makes it impossible to discriminate. Therefore, the detection unit 71 immediately before the stop according to the present embodiment detects that the phase current immediately before the rotor R stops is equal to or less than a predetermined value (for example, 0.9 [A]), and at that time, UVW. The comparison unit 72 and the phase determination unit 73 are operated.

The detection unit 71 immediately before the stop first acquires the amplitude of the current vector from the following equation.

In addition, the phase angle from the q-axis to the current vector can be obtained from the following equation.

FIG. 9 shows the magnitude and phase of the short-circuit brake current vector V2.

When the phase current amplitude ia = 0.9 [A], the phase difference between the d-axis and the current vector is about 99 °. By the way, at this time, the rotation speed is about 13 [rpm] and can be regarded as on the verge of stopping.

That is, when detecting the position of the d-axis during short-circuit braking,
(1) The UVW comparison unit 72 obtains the sector in which the short-circuit brake current vector V2 exists from the magnitude relationship of Iu, Iv, and Iw at the time when the short-circuit brake phase current amplitude reaches the threshold value (for example, 0.9 [A]). ..
(2) The phase determining unit 73 sets the central phase angle θ _M of the obtained sector as the phase angle θ ^∧ of the short-circuit current vector V2 at the time of stop, and then sets a predetermined angle θx in the rotational direction as shown in FIG. For example, advance the phase by 100 °. The angle at that position is the d-axis phase angle θ ₀ , which indicates the stop phase of the rotor with respect to the α-axis.
θ ₀ = θ _M ± θx
This predetermined angle θx corresponds to a value obtained by adding the error angle and 90 °, which is the angle between the d and q axes. The error angle includes the phase difference between the short-circuit brake current vector V2 immediately before stopping and the q-axis.

FIG. 10 is a flowchart showing an outline of a procedure carried out by the control means C using the short-circuit brake control unit 61, the stop phase estimation unit 7, and the storage unit 8. When the program starts,

<Step S1>
Determine if rotation has started. If YES, the process proceeds to step S2, and if NO, the process returns to the front of step S1.

<Step S2>
It is determined whether or not the rotation ON period has ended. Here, it is an ON period during normal rotation during washing and rinsing. If YES, the process returns to step S3, and if NO, the process returns to the front of step S2.

<Step S3>
Upon the end of the rotation period, the short-circuit brake is activated. The short-circuit brake is performed by connecting the switches SW4 and SW5 to 0V in FIG.

<Step S4>
Calculate the amplitude of the short circuit brake current. The magnitude of the short-circuit brake current can be monitored by using Id and Iq as described above, but here, the amplitude is monitored by using the phase current amplitude Im. Im is according to the following equation.

<Step S5>
Judge whether Im <ref. ref is a current value at which it is determined that the rotation has almost stopped. If YES, the process proceeds to step S6, and if NO, the process returns to the front of step S3.

<Step S6>
The sector is determined from the size relationship of Iu, Iv, and Iw. The phase currents Iu, Iv, and Iw are detected from the motor M.

<Step S7>
The stop phase angle θ ₀ of the d-axis is calculated from the central phase θ _M of the sector in Table 1, stored as the initial integration value in the storage unit 8 of FIGS. 3 and 4, and the process returns to the start.

As a result, the positioning current vector V1 is given an initial value in the direction of FIG. 5 (c) close to the d-axis, and synchronous rotation can be smoothly started from this state.

<Second Embodiment>
Next, the second embodiment of the present invention will be described with reference to FIG.

In the algorithm of the above embodiment, the measurement of the central phase θ _M of the short-circuit brake current vector V2 is in sector units. Therefore, a phase error of up to ± 30 ° will occur.

In practice, such an error does not hinder the smooth start-up, but by incorporating an algorithm for increasing the estimation accuracy of the d-axis, a smoother start-up can be realized.

The stop phase estimation unit 7 of the present embodiment uses the center phase angle θ _M of the estimated sector as a reference phase angle, and a correction angle Δ θ derived from a predetermined correspondence relationship with the reference phase angle θ _M based on the phase current. The angle with the above is taken as the phase angle θ ^∧ of the positioning current vector V1, and the phase angle θ ₀ of the d-axis is estimated by adding or subtracting the predetermined angle θ x to this phase angle θ ^∧ .

By doing so, it is possible to estimate the phase angle θ ₀ of the d-axis with higher accuracy by a relatively simple operation.

Specifically, since there is an algorithm shown in Table 2 that approximately estimates the phase at that time from the instantaneous values of the three phases of the triangular sine wave, it is used.

If the correction angle θ based on U, V, and W as shown in Table 2 is used for each sector determined in the above embodiment, the calculation result can be made closer to the true value.

Steps S6a to S6d of FIG. 11 represent a procedure of the phase determination and storage unit applied in place of steps S6 and S7 of the above embodiment.

<Step S6a>
Calculate the correction angle θ ^∧ from θ ^∧ and Δθ by the following equation.

<Step S6b>
Determine if the rotation direction is negative.

<Steps S6c, S6d>
In steps S6c and 6b, the stop phase angle θ ₀ of the d-axis is obtained by ± ± the radian corresponding to the predetermined angle θx = 100 ° according to the rotation direction.

<Step S7a>
The integrated initial value θ ₀ is stored in the storage unit 8, and the process returns to the start.

For example, it is assumed that when the rotor R is stopped at t = 0.8 [s], the phase current in Table 3 below is read at t = 0.78 [s].

Since Iw> Iv> Iu, the short-circuit brake current vector V2 is located in the sector 4 at this point.

Therefore,

According to the calculation of the first embodiment, the temperature is 210 °, so that the phase θ ^∧ of the short-circuit current vector V2 closer to the q-axis phase can be obtained. Then, 332.6 °, which is 100 ° advanced from this 232.6 ° by a predetermined angle, is determined as the phase angle θ ₀ of the d-axis. Therefore, the positioning current vector V1 is given in a direction substantially in line with the d-axis, and it is possible to start synchronous rotation at startup more smoothly from this state.

<Modification example>
Regarding the short-circuit brake, in the above, the short-circuit brake is realized by setting the dq-axis voltage to 0 [V], but the short-circuit brake control unit 161 of FIG. 12 is configured regardless of the dq-axis voltage. In the switching drive circuit, the three-phase U, V depends on whether (1) all the high-side switching elements SW (H) are turned off or (2) all the low-side switching elements SW (L) are turned off. , W may be short-circuited.

According to this, since PWM switching is not performed, there are advantages that there is no influence of dead time, switching noise does not occur, and the calculation load of the computer is light.

Although the embodiments of the present invention have been described above, the rotor phase estimation, the storage mechanism, and the like are not limited to the above-described embodiments.

Other configurations can be variously modified without departing from the spirit of the present invention.

1 ... Washing machine 7 ... Stop phase estimation unit 8 ... Storage unit 15 ... Short-circuit brake control unit C ... Control means M ... Motor R ... Rotor V1 ... Positioning current vector V2 ... Short-circuit brake current vector θ ₀ ... Rotor stop phase θ _M : Central phase angle (reference phase angle)
θx ... Predetermined angle Δθ ... Correction angle

Claims (4)

It is equipped with a pulsator that agitates the laundry, a permanent magnet synchronous motor that drives the pulsator forward and reverse, and a control means that controls the start and stop of the motor with respect to the rotor without a sensor.
The control means includes a short-circuit brake control unit that performs a short-circuit brake when the rotor is stopped from a state in which the rotor is rotating in a predetermined rotation direction, and a phase current that flows through the winding due to the short-circuit brake as a phase current value immediately before the rotor is stopped. It is provided with a stop phase estimation unit that estimates the phase in which the rotor has stopped from the phase current detected when the value falls below a predetermined value, and a storage unit that stores the estimated stop phase. When the rotor is rotated and started in the direction opposite to the predetermined rotation direction, the stop phase of the rotor estimated from the storage unit is taken out, and based on this, a positioning current vector which is a current vector for positioning the rotor at the start of synchronous rotation is generated. A washing machine featuring. In the stop phase estimation unit, the short-circuit brake current vector, which is the vector of the phase current flowing through the winding due to the short-circuit brake, is applied to a plurality of sectors on the static coordinates classified by the magnitude relation of the phase current immediately before the stop. The washing machine according to claim 1, wherein it is determined whether or not the washing machine belongs to a sector. The stop phase estimation unit uses the central phase angle of the determined sector as the phase angle of the short-circuit brake current vector existing near the q-axis of the rotational coordinate system, and estimates the phase angle of the d-axis by adding or subtracting a predetermined angle to this phase angle. The washing machine according to claim 2. The stop phase estimation unit sets the angle obtained by adding the correction angle derived from the correspondence relationship determined in advance based on the phase current to the reference phase angle of the estimated sector as the phase angle of the short-circuit brake current vector existing in the vicinity of the q-axis. The washing machine according to claim 2, wherein a predetermined angle is added to or subtracted from this phase angle to estimate the phase angle of the d-axis.

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