Washing machine

Abstract

The present invention provides a washing machine that can suppress the complication of the structure and the increase in cost, and can perform various monitoring controls with high precision. The washing machine of the present invention includes: a rotary tub that houses laundry, a motor that is a brushless DC motor for rotationally driving the rotary tub, a current detection unit that detects a current flowing through the motor, a control unit that performs vector control on the motor based on the current detected by the current detection unit, and one position sensor that detects the rotational position of the rotor of the motor and outputs a sensor signal, and the control unit performs a prescribed monitoring control based on the sensor signal.

Description

Technical Field

[0001] The present invention relates to a washing machine. Background Art

[0002] The washing machine is configured to use a brushless DC motor as a motor for rotationally driving a rotary tub that houses laundry. Conventionally, as a method for controlling the driving of such a motor, the following sensor-driven configuration and sensorless-driven configuration can be cited. The sensor-driven configuration means a configuration in which a plurality of position sensors for detecting the rotational position of the motor rotor are provided, and the motor is driven based on sensor signals output from the plurality of position sensors. The sensorless-driven configuration means a configuration in which a position sensor is not provided and vector control is performed by detecting the current of the motor. The sensorless-driven configuration has the following advantages compared to the sensor-driven configuration: it can simplify the configuration and can suppress the manufacturing cost to a low level because it does not require a position sensor.

[0003] Patent Documents

[0004] Patent Document 1: Japanese Patent No. 4795628

[0005] Patent Document 2: Japanese Patent No. 6295407

[0006] In the sensorless-driven configuration, there are the following problems: the accuracy of various monitoring controls such as abnormal monitoring control for monitoring abnormalities related to motor rotation such as offset, stop monitoring control for monitoring the stop of the motor due to braking, and imbalance monitoring control for monitoring the imbalance caused by the bias of the laundry in the rotary tub cannot be sufficiently improved. That is, it can be imagined that in the sensorless-driven configuration, various monitoring controls are performed based on the detection result of the current flowing through the motor, that is, the motor current.

[0007] However, the detection accuracy of the motor current may be lowered due to, for example, noise mixed during A / D conversion. In this case, the accuracy of the abnormal monitoring control and the stop monitoring control may be lowered, or false monitoring may occur. In addition, due to various operating conditions and the like, the motor current sometimes does not change depending on the presence or absence of imbalance. In this case, the accuracy of the imbalance monitoring control may be lowered, or false monitoring may occur. Summary of the Invention

[0008] Therefore, a washing machine is provided that can suppress the complication of the structure and the increase in cost, and can perform various monitoring controls with high accuracy.

[0009] The washing machine according to the embodiment includes: a rotary tub for accommodating clothes, a brushless DC motor (i.e., a motor) for rotationally driving the rotary tub, a current detection unit for detecting the current flowing through the motor, a control unit for performing vector control on the motor based on the current detected by the current detection unit, and one position sensor for detecting the rotational position of the rotor of the motor and outputting a sensor signal. The control unit performs a predetermined monitoring control based on the sensor signal.

[0010] According to the above configuration, even with a small number of sensors, it is possible to monitor imbalance. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 FIG. is a partially longitudinally cut side view schematically showing the configuration of the washing machine according to the first embodiment.

[0012] Figure 2 FIG. is a circuit diagram schematically showing the electrical configuration of the washing machine according to the first embodiment.

[0013] Figure 3 FIG. is a diagram schematically showing the configuration of the motor according to the first embodiment.

[0014] Figure 4 FIG. is a diagram schematically showing the configuration of the rotor of the motor according to the first embodiment.

[0015] Figure 5 FIG. is a block diagram schematically showing the specific configuration of the control circuit according to the first embodiment.

[0016] Figure 6 FIG. is a diagram schematically showing the content of the motor control performed by the control circuit according to the first embodiment.

[0017] Figure 7 FIG. is a diagram schematically showing the specific processing content related to the stop monitoring control according to the first embodiment.

[0018] Figure 8 FIG. is one of the diagrams schematically showing the specific processing content related to the abnormality monitoring control according to the first embodiment.

[0019] Figure 9 FIG. is another diagram schematically showing the specific processing content related to the abnormality monitoring control according to the first embodiment.

[0020] Figure 10 FIG. is a diagram schematically showing the specific processing content related to the weight monitoring control according to the first embodiment.

[0021] Figure 11It is a diagram of the phase current waveform of the motor when there is no imbalance in the second embodiment.

[0022] Figure 12 It is a diagram schematically showing the phase current waveform of the motor when there is an imbalance in the second embodiment.

[0023] Figure 13 It is a diagram schematically showing the change in the motor speed during the dehydration process in the second embodiment.

[0024] Figure 14 It is a diagram schematically showing the waveform of the sensor signal output by the position sensor in the second embodiment.

[0025] Figure 15 It is a diagram schematically showing the waveforms of the detected rotation speed signal and the determination value signal when there is no imbalance in the second embodiment.

[0026] Figure 16 It is a diagram schematically showing the waveforms of the detected rotation speed signal and the determination value signal when there is an imbalance in the second embodiment.

[0027] Figure 17 It is a diagram for explaining the content of the digital filter processing in the second embodiment.

[0028] Figure 18 It is a diagram schematically showing the specific processing content related to the imbalance monitoring control in the second embodiment.

[0029] Figure 19 It is a diagram for explaining the content of the digital filter processing in the third embodiment.

[0030] Explanation of reference numerals

[0031] In the drawings, 7 represents a control circuit, 9 represents a position sensor, 31 represents a stator, 32 represents a rotor, 33 represents a magnet, 100 represents a washing machine, 104 represents a rotating tub, 108 represents a pulsator, and 113 represents a motor. Detailed embodiments

[0032] Next, a plurality of embodiments will be described with reference to the drawings. In addition, in each embodiment, components that are substantially the same are given the same reference numerals and description thereof is omitted.

[0033] (First Embodiment)

[0034] Next, with reference to Figures 1 to 10 the first embodiment will be described.

[0035] <Configuration of Washing Machine>

[0036] As shown Figure 1 In the interior of the outer case 101 that forms the outer contour of the washing machine 100, a water tank 102 with an open upper surface and a bottomed cylindrical shape is elastically supported by an elastic suspension mechanism 103. Inside the water tank 102, a rotating tank 104 with an open upper surface and a bottomed cylindrical shape is rotatably provided. Laundry items as washing objects are accommodated inside the rotating tank 104 in a manner that allows loading and unloading.

[0037] At the bottom of the rotating tank 104, a reinforcing member 105 for strengthening the bottom of the rotating tank 104 is provided. The rotating tank 104 is configured to rotate about a vertical axis and serves as both a washing tank and a dehydration tank. The washing tank refers to the tank used for washing during the washing operation of cleaning the washing objects and the rinsing operation of rinsing the washing objects. The dehydration tank refers to the tank used for dehydration during the dehydration operation of dehydrating the washing objects. That is, the washing machine 100 is a so-called vertical-axis type washing machine in which the rotation center axis of the rotating tank 104 extends along the vertical direction.

[0038] The peripheral wall portion of the rotating tank 104 has a plurality of holes 106. These holes 106 are through holes and can conduct water and air. In addition, Figure 1 Only a part of the plurality of holes 106 is shown. An equilibrium ring 107 made of synthetic resin encapsulating a liquid such as brine is installed above the rotating tank 104. Inside the rotating tank 104, specifically, on the inner bottom, a pulsator 108 made of synthetic resin, for example, is rotatably provided as a stirring body. A drainage path 109 is provided below the water tank 102. A drainage valve 110 is provided on the drainage path 109, and by opening the drainage valve 110, the water inside the water tank 102 can be discharged to the outside of the washing machine. In addition, an air trap 111 for water level monitoring is provided at the bottom of the water tank 102.

[0039] A drive mechanism unit 112 is provided at the central part of the lower portion of the water tub 102. The drive mechanism unit 112 includes: a motor 113 that rotationally drives the rotary tub 104, and a clutch mechanism unit 112a including a clutch and a reduction gear. During the washing stroke or the rinsing stroke, the drive mechanism unit 112 transmits the rotational force to the agitator 108 through the clutch mechanism unit 112a. Thus, during the washing stroke or the rinsing stroke, the rotary tub 104 is not rotationally driven, and only the agitator 108 is rotationally driven. At this time, the agitator 108 is rotationally driven with a reduction of 1 / 5. In addition, during the dehydration stroke, the drive mechanism unit 112 transmits the rotational force of the motor 113 to the agitator 108 and the rotary tub 104 through the clutch mechanism unit 112a. Thus, during the dehydration stroke, the agitator 108 and the rotary tub 104 are rotationally driven integrally. At this time, the rotary tub 104 is rotationally driven without deceleration.

[0040] A top cover 114 is provided at the upper portion of the outer case 101. In the top cover 114, a lid 115, such as a folding lid, for opening and closing the laundry inlet / outlet is provided in an openable and closable manner. In addition, an outer tub cover (not shown) is mounted on the upper portion of the water tub 102 in an openable and closable manner. An operation panel 116 is provided at the front portion of the top cover 114. A control unit 117 for controlling all operations of the washing machine 100 is disposed on the back side of the operation panel 116. A water supply mechanism unit 118 for supplying water from a water source into the water tub 102 is provided at the rear portion inside the top cover 114. The water supply mechanism unit 118 includes a water supply valve (not shown), a water supply path (not shown) communicating with the water tub 102, etc. The control unit 117 controls the water supply to the inside of the water tub 102 by controlling the opening and closing of the water supply valve.

[0041] <Electrical Configuration of the Control System of the Washing Machine>

[0042] Figure 2 It is a block diagram showing the function of the drive control system of the motor 113. In this case, the control unit 117 includes a PWM control type inverter, that is, an inverter circuit 1. In addition, PWM is an abbreviation for Pulse Width Modulation. The inverter circuit 1 is formed by connecting six IGBTs 2a to 2f as semiconductor switching elements in a three-phase bridge configuration, and freewheeling diodes 3a to 3f are connected between the collector and emitter of each IGBT 2a to 2f. Each phase output terminal of the inverter circuit 1 is connected to each motor winding 113u, 113v, 113w of the motor 113. In the present embodiment, as the motor 113, an outer rotor type three-phase brushless DC motor is adopted, for example.

[0043] The emitters of the IGBTs 2d, 2e, and 2f on the lower arm side are connected to ground via a shunt resistor 4 that serves as a current detection element. Additionally, the common connection point of the emitters of the IGBTs 2d, 2e, and 2f and the shunt resistor 4 is connected to ground via a resistor element 5 and a capacitor 6. The common connection point of the resistor element 5 and the capacitor 6 is connected to the A / D input 2 terminal of the control circuit 7 and is also connected to the input terminal of an overcurrent determination circuit 8. The overcurrent determination circuit 8 is composed of a comparator or the like. The output signal of the overcurrent determination circuit 8 is an emergency stop signal based on overcurrent detection. When an emergency stop signal is input, the control circuit 7 stops outputting a PWM signal to the inverter circuit 1.

[0044] One position sensor 9 for detecting the rotational position of the rotor is arranged in the motor 113. The position sensor 9 is a magnetic sensor, for example, composed of a Hall IC, and outputs a sensor signal that is a digital signal corresponding to the detection result of the rotational position. The sensor signal output from the position sensor 9 is input to the control circuit 7 via a NOT gate 10. The output terminal of the NOT gate 10 is connected to ground via a capacitor 11.

[0045] The drive power supply circuit 12 is connected to the input side of the inverter circuit 1. The drive power supply circuit 12 performs full-wave voltage doubling rectification on a 100V AC power supply 13 through a full-wave rectifier circuit 14 composed of a diode bridge and two capacitors 15a and 15b connected in series, and supplies a DC voltage of approximately 280V to the inverter circuit 1. Each phase output terminal of the inverter circuit 1 is connected to each phase winding 113u, 113v, 113w of the motor 113. The first power supply circuit 16 steps down the approximately 280V drive power supply supplied to the inverter circuit 1 to generate a 15V power supply and supplies it to the drive circuit 17 and the high-voltage drive circuit 19. The second power supply circuit 18 is a three-terminal regulator for stepping down the above drive power supply to generate a 5V control power supply and supplying it to the control circuit 7, the rotational position sensor 9, the third power supply circuit 20, etc.

[0046] A high-voltage drive circuit 19 is arranged to drive the IGBTs 2a - 2c on the upper arm side in the inverter circuit 1. The third power supply circuit 20 generates a 3.3V power supply using the above 5V and supplies this power supply to the overcurrent determination circuit 8. The A / D input 2 terminal of the control circuit 7 is pulled up to the 3.3V power supply via a resistor element 21. A series circuit of resistor elements 22a and 22b is connected between the output terminal of the drive power supply circuit 12 and ground, and the common connection point of the two is connected to the A / D input 1 terminal of the control circuit 7.

[0047] The control circuit 7 detects the three-phase current supplied to the motor 113 based on the terminal voltage of the shunt resistor 4, and performs vector control, thereby generating PWM signals for the upper and lower three phases in which the voltage rate changes in a sine wave shape. The control circuit 7 outputs the PWW signals to the gates of the IGBTs 2a to 2f constituting the inverter circuit 1 via the drive circuit 17 and, for the upper side, also via the high-voltage drive circuit 19. In the drive circuit 17, the respective input terminals for inputting the PWM signals are pulled down to the ground through the resistors 23.

[0048] In the above configuration, bootstrap capacitors 24d, 24e, and 24f are respectively connected between the emitters of the IGBTs 2d, 2e, and 2f on the lower arm side and the high-voltage drive circuit 19. In the above configuration, with the switching operation of the IGBTs 2a to 2f, the bootstrap capacitors 24d to 24f are charged, thereby generating a power supply voltage for driving the gates of the IGBTs 2a to 2c on the upper arm side of the high-voltage drive circuit 19.

[0049] In the present embodiment, the control circuit 7 functions as a current detection unit that detects the current flowing through the motor 113, and also functions as a control unit that performs vector control of the motor 113 based on the current detected by the current detection unit. In this case, the control circuit 7 controls the motor 113 so that the rotational speed of the motor 113 follows a desired target speed. The control circuit 7 executes predetermined monitoring control based on the sensor signal. Specifically, the control circuit 7 executes one or both of the abnormality monitoring control and the stop monitoring control as the predetermined monitoring control. In addition, the control circuit 7 executes the weight monitoring control as the predetermined monitoring control.

[0050] The abnormality monitoring control is control for monitoring abnormalities related to the rotation of the motor 113 such as offset. The stop monitoring control is control for monitoring the stop of the motor 113 caused by braking such as friction braking or electromagnetic braking. The weight monitoring control is control for calculating the rotational speed of the rotary tub 104 based on the sensor signal when the agitator 108 rotates after the laundry is loaded into the rotary tub 104, and determining the amount of laundry based on the calculated rotational speed.

[0051] <Configuration of the motor>

[0052] As a specific configuration of the motor 113, for example, Figure 3 and Figure 4 as shown. As Figure 3 shown, the motor 113 includes a stator 31 and a rotor 32 disposed on the outer periphery thereof. The stator 31 is configured to integrate the stator core and the stator winding using a molding resin. The rotor 32 is configured to integrate the frame, the rotor core, and a plurality of magnets using a molding resin.

[0053] In this case, if Figure 3 as well as Figure 4 As shown in FIG, the rotor is provided with 12 permanent magnets, namely magnets 33, which are arranged at equal intervals on one circumference. Figure 3 As shown, a position sensor 9 is mounted on the stator 31, near the end of the magnet 33. As previously described, the position sensor 9 is a Hall effect IC capable of sensing magnetism and outputs a sensor signal whose level reverses depending on the north and south poles of the magnet 33. With this configuration, the sensor signal output from the position sensor 9 generates twelve pulse edges, the same number as the magnets 33, for each revolution of the rotor 32.

[0054] <Specific Structure and Functions of the Control Circuit>

[0055] As a specific structure of the control circuit 7 having the function of performing vector control on the motor 113, for example, Figure 5 The structure shown. Figure 5 Here, (α, β) represents an orthogonal coordinate system obtained by orthogonally transforming a three-phase (UVW) coordinate system corresponding to each phase of motor 113, a three-phase brushless DC motor, at 120-degree intervals. Furthermore, (d, q) represents a coordinate system of the secondary magnetic flux that rotates with the rotation of the rotor of motor 113.

[0056] The target speed command ωref output from the microcomputer 41 is provided as a subtrahend value to the subtractor 42. In this specification, the microcomputer may be referred to simply as the microcomputer. Furthermore, the detected speed ω of the motor 113, detected by the estimator 43, is provided as a subtrahend value to the subtractor 42. The subtraction result of the subtractor 42 is provided to the speed PI control unit 44. The speed PI control unit 44 is configured to perform PI control based on the difference between the target speed command ωref and the detected speed ω, generating a q-axis current command value Iqref and a d-axis current command value Idref, and providing these to fixed contacts 45qa and 45da on one side of the selector switches 45q and 45d, respectively.

[0057] The starting current command values Iqs and Ids output by controlling the initial mode output unit 46 by current are supplied to the other fixed contacts 45qb and 45db of the changeover switches 45q and 45d. Moreover, the movable contacts 45qc and 45dc of the changeover switches 45q and 45d are connected to the input terminals for the minuend values of the subtractors 47 and 48. Each of the changeover switches 45q and 45d is configured to be switched and controlled by the microcomputer 41. In addition, during the cleaning or rinsing operation, the d-axis current command value Idref is set to "0", and during the dehydration operation, since weak magnetic field control is performed, the d-axis current command value Idref is set to a specified value.

[0058] The q-axis current value Iq and the d-axis current value Id output from the αβ / dq conversion unit 49 are supplied to the subtractors 47 and 48 as minuend values, and the respective subtraction operation results are supplied to the current PI control units 50q and 50d. Moreover, the current PI control units 50q and 50d perform PI control based on the difference amounts between the q-axis current command value Iqref and the d-axis current command value Idref, generate a q-axis voltage command value Vq and a d-axis voltage command value Vd, and supply them to one fixed contacts 51qa and 51da of the changeover switches 51q and 51d, respectively.

[0059] The starting voltage command values Vqs and Vds output by the voltage control initial mode output unit 52 are supplied to the other fixed contacts 51qb and 51db of the changeover switches 51q and 51d. Moreover, the movable contacts 51qc and 51dc of the changeover switches 51q and 51d are connected to the input terminals of the dq / αβ conversion unit 53. In addition, the changeover switches 51q and 51d are configured to be switched and controlled by the microcomputer 41.

[0060] The rotor position angle of the secondary magnetic flux in the motor 113 detected by the estimator 43, that is, the rotation phase angle θ, is supplied to the dq / αβ conversion unit 53, and is configured to convert the voltage command values Vd and Vq into voltage command values Vα and Vβ based on the rotation phase angle θ. The voltage command values Vα and Vβ output by the dq / αβ conversion unit 53 are supplied to the αβ / UVW conversion unit 54. The αβ / UVW conversion unit 54 has a function of converting the voltage command values Vα and Vβ into three-phase voltage command values Vu, Vv, and Vw and outputting them. The voltage command values Vu, Vv, and Vw are configured to be supplied to the PWM forming unit 55.

[0061] The PWM forming section 55 is configured to output the PWM signals Vup(+,-), Vvp(+,-), and Vwp(+,-) of each phase, which are obtained by modulating a transmission wave, which is a triangular wave of 16 kHz, based on the voltage command values Vu, Vv, and Vw, to the inverter circuit 1. The PWM signals Vup to Vwp are output as signals having a pulse width corresponding to the voltage amplitude of a sine wave so as to supply a sine-wave-like current to each phase winding 113u, 113v, and 113w of, for example, the motor 113.

[0062] In this case, the current flowing through the motor 113 for torque control is detected by the shunt resistor 4. That is, the A / D conversion section 56 performs A / D conversion on the signal at the common connection point of the resistance element 5 and the capacitor 6 or the like to obtain current data Iu and Iv, and outputs the current data Iu and Iv to the UVW / αβ conversion section 57. The UVW / αβ conversion section 57 has a function of estimating the current data Iw of the W phase based on the current data Iu and Iv, and converting the three-phase current data Iu, Iv, and Iw into two-axis current data Iα and Iβ in an orthogonal coordinate system. In addition, as a specific method of this conversion, known methods such as the method disclosed in Patent Document 1 can be adopted.

[0063] Moreover, the UVW / αβ conversion section 57 outputs the two-axis current data Iα and Iβ to the αβ / dq conversion section 49. The αβ / dq conversion section 49 has a function of obtaining the rotor position angle θ of the motor 113 by the estimator 43 during vector control, and converting the two-axis current data Iα and Iβ into a d-axis current value Id and a q-axis current value Iq in a rotating coordinate system (d, q). In addition, as a specific method of this conversion, known methods such as the method disclosed in Patent Document 1 can be adopted.

[0064] Moreover, the αβ / dq conversion section 49 is configured to output the d-axis current value Id and the q-axis current value Iq to the estimator 43 and the subtracters 47 and 48 as described above. The estimator 43 estimates the rotor position angle θ and the rotational speed ω of the motor 113 based on the d-axis current value Id and the q-axis current value Iq, and outputs them to each section. Here, the motor 113 is subjected to DC excitation at the time of starting, and after initializing the rotational position of the rotor, that is, after positioning at the initial value, a starting mode is applied to perform forced commutation. When forced commutation is performed due to the application of this starting mode, the position angle θ is clear even without estimation.

[0065] After starting vector control, estimator 43 is activated to estimate the rotor position angle θ and rotational speed ω of motor 113. In this case, it is configured such that assuming the rotor position angle θn output from estimator 43 to αβ / dq conversion unit 49, estimator 43 estimates the rotor position angle θn based on the correlation between the rotor position angle θn-1 estimated according to the current values Id and Iq and using vector operations and the rotor position angle θn-2 estimated one cycle before.

[0066] In the above configuration, the outline of control with microcomputer 41 as the main body is as Figure 6 shown. First, when microcomputer 41 starts, for example, a washing operation, a rinsing operation, or a dehydration operation, it executes the starting process of motor 113, which is the process of steps S101 to S105. Specifically, in step S101, the positioning control of the rotor of motor 2 is started. In this case, using microcomputer 41, the movable contacts 51qc and 51dc of changeover switches 51q and 51d are connected to the fixed contacts 51qb and 51db, and thus, through voltage control initial mode output unit 52, the voltage command value of the initial mode for DC excitation is provided to dq / αβ conversion unit 53.

[0067] Accordingly, the process of step S102 is executed, and the voltage for DC excitation is output from inverter circuit 1 to the windings of motor 113. In this configuration, it is configured such that the output voltage linearly increases from 0V to 80V, for example, in 2 seconds. That is, it is configured such that the voltage command value required to output such a linear output voltage from inverter circuit 1 is provided to dq / αβ conversion unit 53 as the voltage command value of the initial mode for DC excitation. By performing the above DC excitation, in step S103, the rotational position of the rotor of motor 113 is initialized and positioned. During this positioning control, the rotational speed of motor 113, that is, the rotational speed, is 0 rpm, the d-axis current changes in a manner starting from 0A, and the q-axis current is 0A.

[0068] Next, step S104 is entered, and forced commutation control is started. In this case, it is configured such that using microcomputer 41, the movable contacts 45qc and 45dc of changeover switches 45q and 45d are connected to the fixed contacts 45qb and 45db, and thus, through current control initial mode output unit 46, the current command value for forced commutation is provided to subtracters 47 and 48. In addition, changeover switches 51q and 51d are configured such that their movable contacts 51qc and 51dc are connected to the fixed contacts 51qa and 51da, and thus, the q-axis voltage command value Vq and the d-axis voltage command value Vd from current PI control units 50q and 50d are provided to dq / αβ conversion unit 53.

[0069] Accordingly, the motor 113 is forced to commutate and then starts to rotate, and the rotational speed, i.e., the rotation speed, gradually increases. In the case of this configuration, it is configured that, as shown in step S105, the rotation speed of the motor 113 is linearly increased from 0 rpm to, for example, 30 rpm in 3 seconds, i.e., the output frequency and the frequency corresponding to 0 rpm are linearly increased to the frequency corresponding to 30 rpm in 3 seconds, and PI control, i.e., current control, is performed on the d-axis current in such a way that it is fixed at a predetermined constant value such as 7 A. In addition, the q-axis current is fixed at 0 A.

[0070] That is, it is configured that, in order to execute the current command value required for the forced commutation control for obtaining such d-axis current and q-axis current as the current command value of the initial mode for forced commutation, it is provided from the current control initial mode output unit 46 to the subtracters 47, 48. Moreover, during the above-mentioned forced commutation control, the rotation speed of the motor 113, i.e., the rotational speed, rises from 0 rpm to 30 rpm, the d-axis current is maintained at approximately 7 A, and the q-axis current is 0 A. In addition, in the present embodiment, since the motor 113 is configured such that the electrical angle is 12 cycles with respect to 1 cycle of the mechanical angle, the forced commutation of 30 rpm corresponds to the output frequency of 150 Hz.

[0071] Next, step S106 is entered, and the control of converting the forced commutation control to torque control, i.e., vector control, is executed. In the case of this configuration, the movable contacts 45qc, 45dc of the changeover switches 45q, 45d are connected to the fixed contacts 45qa, 45da by using the microcomputer 41, and thus the current command value from the speed PI control unit 44 is provided to the subtracters 47, 48. Moreover, the above-mentioned switching control is configured to be executed gradually. Specifically, current control, i.e., PI control, is performed in such a way that the d-axis current gradually decreases from 7 A to 0 A, and current control, i.e., PI control, is performed in such a way that the q-axis current rises from 0 A to a predetermined value, i.e., for example, 7 A.

[0072] Moreover, thereafter, step S107 is entered, and it is configured that PI control is performed on the q-axis current based on the difference between the actual rotation speed and the target rotation speed. Accordingly, it is possible to quickly respond to the target rotation speed, and thus good control responsiveness can be obtained. During the execution of such rotation speed control, the rotation speed of the motor 113, i.e., the rotational speed, rises so as to reach the target rotation speed. Moreover, the d-axis current is maintained at 0 A, and the q-axis current is increased or decreased based on the difference between the actual rotation speed and the target rotation speed.

[0073] Next, with reference to Figures 7 to 10 , the specific processing contents related to various monitoring controls performed by the control circuit 7 configured as described above will be described.

[0074] [1]Specific processing content related to stop monitoring control

[0075] When the control circuit 7 is in the dehydration operation, more specifically, in the final dehydration operation, it performs Figure 7 processing of the content as shown. First, in step S201, when the dehydration operation starts, it proceeds to step S202 and performs lid locking. When the lid locking is performed, the lid 115 cannot be opened.

[0076] After performing step S202, it proceeds to step S203 and determines whether the dehydration operation has ended. When the dehydration operation is still ongoing, in step S203, it is "NO", and the determination in step S203 is made again. When the dehydration operation ends, in step S203, it is "YES", and it proceeds to step S204. In step S204, braking for stopping the rotation of the motor 113 is started.

[0077] When the rotation of the motor 113 starts to stop by performing the braking, the number of times the magnet 33 of the rotor 32 passes through the position sensor 9 gradually decreases during one rotation, and finally the magnet 33 no longer passes through the position sensor 9, and the sensor signal does not change, that is, the level of the sensor signal is fixed at a high level or a low level. Therefore, in the present embodiment, considering these aspects, after performing step S204, the processing corresponding to the stop monitoring control for monitoring the stop of the motor 113, that is, step S205, is performed. That is, in step S205, it is determined whether the sensor signal has not changed for a specified determination time Ta or more.

[0078] In the present embodiment, the determination time Ta, which is the threshold for stop monitoring, is set to a time that can ensure both the safety and convenience of the user, for example, 1.2 seconds. Ensuring safety corresponds to the case where the rotation of the motor 113 has completely stopped, or the case where the rotation of the motor 113 is suppressed to such an extent that there is no problem even if the user touches the rotating tub 104 or the like. Ensuring convenience corresponds to the case where the time from the end of the dehydration operation until the laundry can be taken out is not too long so as not to cause inconvenience to the user. Since the optimum value of this determination time Ta changes according to the number of poles of the rotor 32, that is, the number of magnets 33, etc., it can be appropriately changed according to the number of poles of the rotor 32, etc.

[0079] When the state where the level of the sensor signal does not change is less than the determination time Ta, in step S205, it is "NO", and the determination in step S205 is made again. When the state where the level of the sensor signal does not change continues for the determination time Ta or more, in step S205, it is "YES", and the process proceeds to step S206. In step S206, the lid lock is released, and the state is presented such that the lid 115 can be opened. After executing step S206, this process ends.

[0080] [2] Specific processing content related to abnormal monitoring control

[0081] The control circuit 7 performs: during the cleaning operation, the rinsing operation, or the dehydration operation, Figure 8 the first specific processing of the content as shown, and Figure 9 any one of the second specific processing of the content as shown. As Figure 8 shown, in the first specific processing, first, in step S301, the rotation of the motor 113 is started to rotate the rotary tub 104. When an abnormality related to the rotation of the motor 113 such as an offset occurs, since the rotational speed of the motor 113, that is, the rotation speed, is reduced compared to the original value, that is, the target speed, the number of times the magnet 33 of the rotor 32 passes through the position sensor 9 during one rotation also decreases, and the state where the sensor signal does not change is longer than the normal time.

[0082] Therefore, in the first specific processing, taking this into account, after executing step S301, the process corresponding to the abnormal monitoring control for monitoring the abnormality related to the rotation of the motor 113, that is, step S302, is executed. That is, in step S302, it is determined whether the sensor signal has not changed for a specified determination time Tb or more. In the present embodiment, the determination time Tb, which is the threshold for abnormal monitoring, is set to: for example, 0.2 seconds. In addition, the determination time Tb is: a time that is long enough compared to the time during which the state where the sensor signal does not appear to change continues when the motor 113 is rotationally driven at the lowest rotational speed imaginable during the operation being performed at this time, and the time from the occurrence of an abnormality such as an offset until the abnormality is detected is not too long, and can be appropriately changed.

[0083] When the state where the level of the sensor signal does not change is less than the determination time Tb, in step S302, it is "NO", and the determination in step S302 is performed again. When the state where the level of the sensor signal does not change continues for the determination time Tb or more, in step S302, it is "YES", and the process proceeds to step S303. In step S303, when an abnormal situation such as an offset occurs is detected, the power supply to the motor 113 is stopped. After performing step S303, the first specific process ends. Thus, in the abnormal situation monitoring control included in the first specific process, when the sensor signal in the rotation control in which the control circuit 7 controls the rotation of the motor 113 does not change for a predetermined determination time Tb or more, an abnormal situation related to the rotation of the motor 113 is detected.

[0084] As Figure 9 shown, the difference between the second specific process and the first specific process is that step S312 is provided in place of the process corresponding to the abnormal situation monitoring control, that is, step S302. As described above, when an abnormal situation related to the rotation of the motor 113 such as an offset occurs, the rotation speed of the motor 113 decreases compared to the target speed. Therefore, in step S312 of the second process, it is determined whether the difference between the rotation speed of the motor 113 and the target speed is equal to or more than a predetermined threshold speed.

[0085] The rotation speed of the motor 113 can be calculated based on the sensor signal. In the present embodiment, as an example of determining whether the above difference is equal to or more than the threshold speed, it can be determined whether the rotation speed of the motor 113 is equal to or less than half of the target speed. Therefore, in the present embodiment, the threshold speed that is the threshold for abnormal situation monitoring is a value that varies according to the rotation speed of the motor 113 and the target speed.

[0086] When the difference between the rotation speed of the motor 113 and the target speed is less than the threshold speed, that is, when the rotation speed of the motor 113 exceeds half of the target speed, in step S312, it is "NO", and the determination in step S312 is performed again. When the difference between the rotation speed of the motor 113 and the target speed is equal to or more than the threshold speed, that is, when the rotation speed of the motor 113 is equal to or less than half of the target speed, in step S312, it is "YES", and the process proceeds to step S303. Thus, in the abnormal situation monitoring control included in the second specific process, when the difference between the rotation speed of the motor 113 calculated based on the sensor signal in the rotation control for controlling the rotation of the motor 113 and the target speed is equal to or more than a predetermined threshold speed, an abnormal situation related to the rotation of the motor 113 is detected.

[0087] [3] Specific processing content related to weight monitoring control

[0088] When the control circuit 7 starts a washing operation or the like, it performs Figure 10 processing as shown, and determines the amount of laundry loaded into the rotary tub 104. In this case, Figure 10 the series of processing shown corresponds to the aforementioned weight monitoring control. First, in step S401, monitoring of the sensor signal is started, and after that, the number of pulses of the sensor signal is measured.

[0089] After step S401 is executed, the process proceeds to step S402, and the motor 113 is driven for 1 second so that the rotary tub 104 rotates in the forward rotation direction, that is, forward rotation drive is performed for 1 second. After step S402 is executed, the process proceeds to step S403, and the drive of the motor 113 is stopped, and a period of 3 seconds elapses, that is, the drive stop continues for 3 seconds. At this time, although the driving force of the motor 113 is not applied to the rotary tub 104, it rotates in the forward rotation direction due to inertia, that is, it idles in the forward rotation direction.

[0090] After step S403 is executed, the process proceeds to step S404, and it is determined whether the rotation of the rotary tub 104 has stopped. If the rotation of the rotary tub 104 has not stopped, in step S404, it is "NO", and the determination of step S404 is made again. If the rotation of the rotary tub 104 has stopped, in step S404, it is "YES", and the process proceeds to step S405. In step S405, the number of pulses of the sensor signal during the period when the rotary tub 104 rotates in the forward rotation direction is stored. The number of pulses stored in step S405 corresponds to the number of rotations of the rotary tub 104 in the forward rotation direction, that is, the rotational speed in the forward rotation direction.

[0091] After step S405 is executed, the process proceeds to step S406, and the motor 113 is driven for 1 second so that the rotary tub 104 rotates in the direction opposite to the forward rotation direction, that is, the reverse rotation direction, that is, reverse rotation drive is performed for 1 second. After step S406 is executed, the process proceeds to step S407, and the drive of the motor 113 is stopped, and a period of 3 seconds elapses, that is, the drive stop continues for 3 seconds. At this time, although the driving force of the motor 113 is not applied to the rotary tub 104, it rotates in the reverse rotation direction due to inertia, that is, it idles in the reverse rotation direction.

[0092] After step S407 is executed, step S408 is entered to determine whether the rotation of the rotary groove 104 has stopped. If the rotation of the rotary groove 104 has not stopped, in step S408, it is "NO", and the determination of step S408 is made again. If the rotation of the rotary groove 104 has stopped, in step S408, it is "YES", and step S409 is entered. In step S409, store: the number of pulses of the sensor signal during the rotation of the rotary groove 104 in the reverse direction. The number of pulses stored in step S409 corresponds to the number of rotations of the rotary groove 104 in the reverse direction, that is, the rotational speed in the reverse direction. After step S409 is executed, step S410 is entered.

[0093] In step S410, based on the number of pulses stored in step S405 and the number of pulses stored in step S409, that is, based on the number of pulses corresponding to the rotational speed in the forward direction and the number of pulses corresponding to the rotational speed in the reverse direction, the weight of the laundry is estimated. The estimation here is made based on the following idea. That is, when more laundry is loaded into the rotary groove 104, that is, when the weight of the laundry is larger, the time until the rotation stops due to inertia is shorter. However, when less laundry is loaded into the rotary groove 104, that is, when the weight of the laundry is smaller, the time until the rotation stops due to inertia is longer.

[0094] Therefore, it can be presumed that the larger the number of pulses stored in steps S405 and S409, the smaller the weight of the laundry, and it can also be presumed that the smaller the number of pulses stored in steps S405 and S409, the larger the weight of the laundry. In addition, through experiments in advance, a chart or the like showing the relationship between such number of pulses and the weight of the laundry can be created and stored. In step S410, by referring to this chart, not only the magnitude of the weight of the laundry can be estimated, but also the value of the weight can be estimated. After step S410 is executed, this process ends.

[0095] In this embodiment, the average value between the number of pulses corresponding to the rotational speed in the forward direction and the number of pulses corresponding to the rotational speed in the reverse direction is used for weight estimation. The reason for this is as follows. That is, needless to say, compared with estimating the weight using only one of the number of pulses corresponding to the rotational speed in the forward direction and the number of pulses corresponding to the rotational speed in the reverse direction, estimating the weight using the average value of the above two numbers of pulses can improve the estimation accuracy.

[0096] In addition, although it depends on the type of washing machine, there is sometimes a structure in which the time until the inertial rotation stops is different when rotating in the forward rotation direction and when rotating in the reverse rotation direction. Therefore, compared to the case where either the number of pulses corresponding to the rotation speed in the forward rotation direction or the number of pulses corresponding to the rotation speed in the reverse rotation direction is obtained and the weight is estimated using the average value, in this embodiment, estimating the weight using the average value of the number of pulses corresponding to the rotation speed in the forward rotation direction and the number of pulses corresponding to the rotation speed in the reverse rotation direction can improve the estimation accuracy more.

[0097] According to the present embodiment described above, the following effects can be obtained.

[0098] In the washing machine 100 of the present embodiment, the control circuit 7 that controls the drive of the motor 113 that rotationally drives the rotary tub 104 detects the current flowing through the motor 113 to perform vector control, that is, the present embodiment adopts a sensorless drive configuration. However, in the present embodiment, one position sensor 9 that detects the rotational position of the rotor 32 of the motor 113 and outputs a sensor signal is provided. According to this one position sensor 9, since the error of the magnetic pole position becomes large, it cannot be used for torque generation or rotational drive, but it can be fully used for various monitoring controls.

[0099] Therefore, the control circuit 7 executes a predetermined monitoring control based on the sensor signal output from the one position sensor 9. In this way, it is possible to suppress a decrease in accuracy and false monitoring that may occur when performing various monitoring controls based on the detection result of the current flowing through the motor, that is, the motor current, and thus the reliability of various monitoring controls can be improved. In this case, one position sensor 9 is added to the ordinary sensorless drive configuration, but compared to the sensor drive configuration provided with three position sensors, the structure is simplified and the manufacturing cost is also reduced. Therefore, according to the present embodiment, it is possible to suppress the complication of the structure and the increase in cost, and an excellent effect of being able to perform various monitoring controls with high accuracy can be obtained.

[0100] In the present embodiment, the control circuit 7 executes a stop monitoring control for monitoring the stop of the motor 113 due to braking as a predetermined monitoring control. In the stop monitoring control, the control circuit 7 monitors the stop of the motor 11 due to braking when the sensor signal does not change for a specified determination time Ta or more. In this case, after the control circuit 7 monitors the stop of the motor 113 due to braking, it releases the lid lock. In this way, since the stop of the motor 113 due to braking can be reliably monitored, the safety of the lid lock is improved.

[0101] In addition, in the present embodiment, the control circuit 7 executes an abnormality monitoring control for monitoring an abnormality related to the rotation of the motor 113 as a prescribed monitoring control. The control circuit 7 can perform the following first specific process as the abnormality monitoring control. In the first specific process, when the sensor signal does not change for a prescribed determination time Tb or more in the rotation control for controlling the rotation of the motor 113, it is monitored that an abnormality related to the rotation of the motor 113 has occurred. In addition, the control circuit 7 can also perform the following second specific process as the abnormality monitoring control. In the second specific process, when the difference between the rotation speed of the motor 113 calculated based on the sensor signal in the rotation control for controlling the rotation of the motor 113 and the target speed is equal to or more than a prescribed threshold speed, it is monitored that an abnormality related to the rotation of the motor 113 has occurred.

[0102] According to the first specific process and the second specific process, it is possible to quickly and reliably monitor an abnormality related to the rotation of the motor 113. In this way, since it is possible to quickly and reliably monitor an out-of-balance or the like, it is possible to prevent the occurrence of overheating due to the flow of an excessive current, and thus the safety is improved. In the present embodiment, as a specific method for determining whether or not the above difference in the second specific process is equal to or more than the threshold speed, a method of determining whether or not the rotation speed of the motor 113 is equal to or less than half of the target speed is adopted.

[0103] According to this specific method, the threshold speed that is the threshold for abnormality monitoring is a value that changes according to the rotation speed of the motor 113 and the target speed. That is, in this case, even if the rotation speed of the motor 113 changes according to the operation state of the washing machine 100, the threshold speed also changes similarly according to the change. Therefore, there will be no problem that the accuracy of abnormality monitoring decreases along with the change in the rotation speed. In other words, according to the above method, even if the rotation speed of the motor 113 changes, it is possible to maintain the accuracy of abnormality monitoring well.

[0104] In the present embodiment, the control circuit 7 executes a weight monitoring control as a prescribed monitoring control. In the weight monitoring control, after the laundry is loaded into the rotary tub 104, the rotation speed of the rotary tub 104 is calculated based on the sensor signal when the agitator 108 rotates, and the amount of the laundry is determined based on the calculated rotation speed. In this way, it is possible to reliably monitor the rotation amount of the motor 113 that is difficult to monitor in a general sensorless drive configuration, and thus the monitoring accuracy of the amount of the laundry is improved. As a result, it is possible to obtain the effects of saving water, detergent, etc. used for washing.

[0105] (Second Embodiment)

[0106] Next, the second embodiment will be described with reference to Figures 11 to 18 as follows.

[0107] The difference between the second embodiment and the first embodiment lies in the content controlled by the control circuit 7. In addition, regarding the configuration of the washing machine 100, since it is common to the first embodiment, the drawings related to the first embodiment such as Figures 1 to 5 can be referred to for description.

[0108] In a sensorless drive configuration, there are the following problems. That is, even if an imbalance is caused by the bias of the laundry in the rotating tub, sometimes the current flowing through each phase of the motor, that is, the phase current of the motor, does not change with the imbalance. Figure 11 represents the phase current waveform of the motor 113 when there is no imbalance in the configuration of this embodiment. In addition, Figure 12 represents the phase current waveform of the motor 113 when an imbalance of about 3000 g of lower imbalance occurs, for example, in the configuration of this embodiment.

[0109] In this embodiment, during the dehydration process of the laundry dehydration, when the rotating tub 104 is rotated, the rotational speed of the motor 113 is advanced as Figure 13 shown. That is, when the dehydration operation starts, the rotational speed of the motor 113 is temporarily increased at a specified slope. After that, when it reaches the acceleration period after passing through a constant speed period of, for example, 130 rpm, it is increased at a steeper slope than the initial slope. Figure 11 and Figure 12 show the phase current waveforms of the motor 113 during this acceleration period.

[0110] As shown in Figure 11 and Figure 12 the phase current waveform of the motor 113 shows a monotonic increase in current due to acceleration, but there is no increase or decrease per revolution caused by the presence or absence of imbalance, and no significant difference caused by the presence or absence of imbalance can be seen. Based on this situation, in a sensorless drive configuration, it is difficult to accurately monitor the imbalance based on the detection result of the current flowing through the motor 113.

[0111] Therefore, the control circuit 7 of this embodiment executes imbalance monitoring control as a specified monitoring control, where this imbalance monitoring control is: when the rotating tub 104 is rotated during the dehydration process of the laundry dehydration, the rotational speed of the motor 113 is obtained based on the sensor signal output from the position sensor 9, and the imbalance caused by the bias of the laundry in the rotating tub 104 is monitored based on the change in the obtained rotational speed.

[0112] The sensor signal output from the position sensor 9 is, for example,Figure 14 A pulse waveform as shown. In this case, the rotational speed, i.e., the rotation speed, of the motor 113 is detected by, for example, the time tx between the falling edge and the next rising edge of the sensor signal, i.e., the time between the edges. In the configuration of the present embodiment, since the motor 113 is a multi-pole motor, as the sensor signal, a waveform in which a plurality of pulses appear during one rotation is presented. Therefore, in the configuration of the present embodiment, a plurality of detection values of the rotational speed can be obtained during one rotation.

[0113] The rotational speed of the motor 113 detected based on the time tx between the edges of such a sensor signal, i.e., the sensor signal, varies greatly depending on the presence or absence of imbalance. The reason is as follows. That is, for the motor 113, a plurality of magnets 33 are arranged at equal intervals on the rotor 32. Therefore, although the time tx between the edges of the sensor signal is equally spaced when no imbalance occurs, it is not equally spaced but deviated when an imbalance occurs. As a result, the rotational speed of the motor 113 detected based on the sensor signal varies greatly depending on the presence or absence of imbalance.

[0114] Refer to Figure 15 and Figure 16 , this difference will be described. In the following description, the case of the rotational speed of the motor 113 detected based on the sensor signal is sometimes simply referred to as the detected rotational speed. Figure 15 represents a signal for representing the detected rotational speed when there is no imbalance, i.e., the detected rotational speed signal, and a determination value signal obtained by performing digital filter processing including various signal processes described later on the detected rotational speed signal. In addition, Figure 16 represents the detected rotational speed signal and the determination value signal when there is an imbalance. As shown in Figure 15 and Figure 16 , the detected rotational speed signal when there is an imbalance shows a waveform with a large variation during each rotation compared to the detected rotational speed signal when there is no imbalance.

[0115] In this way, although the difference caused by the presence or absence of imbalance is obvious from the waveform of the detected rotational speed signal, it is difficult to perform digital processing while keeping this waveform unchanged to determine the presence or absence of imbalance. Therefore, in the present embodiment, in the imbalance monitoring control, the control circuit 7 extracts a signal corresponding to the frequency component of the variation during one rotation of the motor 113, i.e., the determination value signal, by performing digital filter processing on the detected rotational speed signal. Moreover, the control circuit 7 monitors the imbalance based on the extracted determination value signal. Specifically, the determination value signal is compared with a threshold signal representing a specified threshold.

[0116] In this embodiment, the above digital filter processing includes: a first process that is a low-pass filter process, a second process that is a band-pass filter process, a third process that is a multiplication process, and a fourth process that is a low-pass filter process. Additionally, in the following description and Figure 17 etc., the case of a low-pass filter is simply referred to as LPF, and the case of a band-pass filter is simply referred to as BPF.

[0117] As Figure 17 shown, the waveform of the detected rotational speed signal contains high-frequency noise with relatively high frequencies. Therefore, in the first process, an LPF process is performed on the detected rotational speed signal. The cut-off frequency of the LPF in the first process is: a frequency higher than the cut-off frequency of the LPF in the fourth process described later, and is set to a relatively high frequency such that the above high-frequency noise can be removed. Additionally, in the following description and Figure 17 etc., the cases of the LPF processes in the first process and the fourth process are respectively referred to as LPF "weak" and LPF "strong" for distinction.

[0118] The signal after the first process, which is the LPF "weak" process, as Figure 17 shown, is the signal after removing high-frequency noise from the detected rotational speed signal. The passband of the BPF in the second process is set so as to pass the frequency band corresponding to one rotation of the rotary groove 104. The signal after the second process, which is the BPF process, as Figure 17 shown, is the signal after removing the DC component from the signal after the first process and extracting the AC component of the frequency band corresponding to one rotation of the rotary groove 104.

[0119] In the BPF process, negative values are also output in terms of calculation. Therefore, in the third process, a multiplication process is performed. Thus, as Figure 17 shown, the signal after the third process is the signal after removing the negative component. The cut-off frequency of the LPF "strong" in the fourth process is: a frequency lower than the cut-off frequency of the LPF "weak" in the first process, and is set to a frequency that only allows approximately the DC component to pass. The signal after the fourth process, which is the LPF "strong" process, as Figure 17 shown, is a signal that only has approximately the DC component, and this signal corresponds to the determination value signal described above.

[0120] Next, with reference to Figure 19 , the specific processing content related to the unbalance monitoring control performed by the control circuit 7 with the above configuration will be described. When the control circuit 7 is in the dehydration operation, it performs Figure 19Processing of the content as shown. First, after starting the dehydration operation in step S501, it proceeds to step S502 to determine whether it is the constant speed period. If it is the constant speed period, in step S502, it is "YES", and it proceeds to step S503. In step S503, the average value of the determination values in the second half of the constant speed period is calculated. The reason for this is that in the first half of the constant speed period, the detected rotation speed signal may be unstable, and thus the determination value signal may be unstable. If such a signal is used for determination, false monitoring may occur.

[0121] After executing step S503, it proceeds to step S504 to perform a comparison of the magnitude between the average value of the determination values calculated in step S503 and a specified threshold value. Specifically, it determines whether the average value of the determination values is above the threshold value. If the average value of the determination values is less than the threshold value, in step S504, it is "NO", and it returns to step S502. On the other hand, if the average value of the determination values is above the threshold value, in step S504, it is "YES", and it proceeds to step S505. In step S505, the motor 113 stops rotating, and thus the rotating tank 104 stops rotating, and imbalance correction is performed by water injection. After executing step S505, it returns to step S502.

[0122] When the constant speed period ends and it transfers to the acceleration period, in step S502, it is "NO", and it proceeds to step S506. Step S506 is a process for determining which of the first half and the second half of the acceleration period it is, and it determines whether the detected rotation speed is below a specified number. The specified rotation speed is set to a rotation speed at which it can be determined which of the first half and the second half of the acceleration period it is. If it is in the second half of the acceleration period and the detected rotation speed exceeds the specified number, in step S506, it is "NO", and this processing ends.

[0123] On the other hand, if it is in the first half of the acceleration period and the detected rotation speed is below the specified number, in step S506, it is "YES", and it proceeds to step S507. In step S507, a comparison of the magnitude between the determination value and a specified threshold value is performed. Specifically, it determines whether the determination value is above the threshold value. If the determination value is less than the threshold value, in step S507, it is "NO", and it returns to step S506. On the other hand, if the determination value is above the threshold value, in step S507, it is "YES", and it proceeds to step S508.

[0124] In step S508, the motor 113 stops rotating, and accordingly the rotating tub 104 stops rotating, and imbalance correction based on water injection is performed. After step S508 is executed, the process returns to step S506. Thus, in the present embodiment, although during the constant speed period and the first half of the acceleration period when the detected rotational speed is below a specified number, imbalance monitoring control for monitoring the imbalance caused by the bias of the laundry in the rotating tub 104 is performed, during the second half of the acceleration period when the detected rotational speed exceeds the specified number, the imbalance monitoring control is not performed.

[0125] According to the present embodiment described above, the control circuit 7 executes imbalance monitoring control as the specified monitoring control, in which, when the rotating tub 104 rotates during the dehydration stroke of laundry dehydration, the rotational speed of the motor 113 is obtained based on the sensor signal, and the imbalance is monitored based on the variation of the obtained rotational speed. In the configuration of the present embodiment, even if an imbalance occurs, the phase current of the motor 113 does not show a variation accompanying the imbalance. However, the rotational speed detected based on the sensor signal shows a large variation caused by the presence or absence of the imbalance.

[0126] In the present embodiment, the imbalance is monitored based on the rotational speed showing a large variation caused by the presence or absence of such an imbalance, and thus, the excellent effect of good monitoring accuracy can be obtained. Further, in the present embodiment, the control circuit 7 performs vector control on the motor 113, controls it at a specified rotational speed, and performs: imbalance monitoring control based on the sensor signal. In this way, it is possible to suppress: the situation where the rotational variation becomes large, and the vibration and noise increase, and it is possible to execute the imbalance monitoring control.

[0127] In the above configuration, the motor 113 is a multi-pole motor, which includes: a rotor 32 provided with a plurality of magnets 33. Further, on the stator 31 of the motor 113, one position sensor 9 as a magnetic sensor is provided, and the imbalance monitoring control is performed based on the variation of the rotational speed, where the variation of the rotational speed is obtained based on the sensor signal output from the one position sensor 9. According to this configuration, a plurality of rotational speed detection values are obtained during one rotation through the sensor signal output from the one position sensor 9. Therefore, according to the present embodiment, only one position sensor 9 needs to be provided, and thus, it is possible to suppress the complication of the structure and the increase in cost, and to monitor the imbalance with high precision.

[0128] In this embodiment, in the unbalance monitoring control, the control circuit 7 extracts, by performing digital filter processing on the obtained rotational speed of the motor 113, a signal of a frequency component corresponding to the variation during one rotation of the motor 113, and monitors the unbalance based on the extracted signal of the frequency component. In this way, it is possible to monitor the unbalance on the basis of excluding the influence of noise caused by installation errors of the position sensor 9, the magnet 33, etc., and electrical noise overlapping with the sensor signal output from the position sensor 9. Therefore, the monitoring accuracy can be further improved.

[0129] (Third Embodiment)

[0130] Next, with reference to Figure 19 , a third embodiment in which the content of the unbalance monitoring control is changed with respect to the second embodiment will be described.

[0131] In the unbalance monitoring control of this embodiment, the control circuit 7 monitors the unbalance based not only on the obtained rotational speed of the motor 113 but also on the detected current flowing through the motor 113. Therefore, the difference between this embodiment and the second embodiment lies in the content of the digital filter processing. As Figure 19 shown, in the digital filter processing of this embodiment, in addition to each process included in the digital filter processing of the second embodiment, a multiplication process performed before the first process is added.

[0132] In the multiplication process, the following process is performed: multiplying the detected rotational speed signal and the motor current signal corresponding to the detected value of the current flowing through the motor 113, that is, the torque current. The signal after this multiplication process is Figure 19 the signal as shown. In this case, in the first process, the signal after the multiplication process obtained by multiplying the detected rotational speed signal and the motor current signal is subjected to an LPF "weak" process.

[0133] According to this embodiment described above, the control circuit 7 monitors the unbalance based not only on the detected rotational speed but also on the motor current in the unbalance monitoring control. In this way, when the motor current, that is, the torque current varies significantly depending on the presence or absence of unbalance, the finally obtained determination value changes significantly depending on the presence or absence of unbalance, so that the monitoring accuracy of monitoring the presence or absence of unbalance based on comparison with a threshold value can be further improved.

[0134] In addition, when the responsiveness of the rotational speed control of the motor 113 is poor, the detected rotational speed will vary due to the presence or absence of imbalance. Moreover, when the responsiveness of the rotational speed control of the motor 113 is good, the motor current will vary due to the presence or absence of imbalance. Therefore, according to the imbalance monitoring control of the present embodiment, the imbalance is monitored based on both the detected rotational speed and the motor current. Thus, regardless of the quality of the responsiveness of the rotational speed control of the motor 113, the imbalance can be monitored with high precision.

[0135] In addition, in the present embodiment, although both the detected rotational speed signal corresponding to the detected rotational speed and the motor current signal corresponding to the motor current are used for the monitoring of the imbalance, for example, the amount of laundry loaded into the rotary tub 104 can also be measured by a weight sensor or the like, and based on the measurement result, any one of the detected rotational speed signal and the motor current signal can be selected for use in the monitoring of the imbalance.

[0136] (Other Embodiments)

[0137] In addition, the present invention is not limited to the embodiments described above and depicted in the drawings, and can be arbitrarily modified, combined, or extended within the scope of its gist.

[0138] The numerical values and the like shown in the above embodiments are merely examples and are not limited thereto.

[0139] The present invention is not limited to the vertical-axis type washing machine 100, and can also be applied to all types of washing machines such as drum washing machines.

[0140] As the position sensor 9, it is not limited to a magnetic sensor such as a Hall IC, and various sensors configured to detect the rotational position of the rotor 32 of the motor 113 and output a sensor signal can also be used.

[0141] Although multiple embodiments of the present invention have been described above, these embodiments are presented only as examples and are not intended to limit the scope of the present invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made within the scope of the gist of the invention. These embodiments and their modifications are included in the scope and gist of the present invention, and are also included in the scope of the invention described in the claims and its equivalents.

Claims

1. A washing machine, comprising: A rotary tub for accommodating laundry; A motor, which is a brushless DC motor, for rotationally driving the rotary tub; A current detection unit for detecting the current flowing through the motor; A control unit for performing vector control of the motor based on the current detected by the current detection unit; and One position sensor for detecting the rotational position of the rotor of the motor and outputting a sensor signal; The control unit performs a prescribed monitoring control based on the sensor signal; The control unit performs one or both of an abnormality monitoring control and a stop monitoring control as the prescribed monitoring control. The abnormality monitoring control monitors an abnormality related to the rotation of the motor, and the stop monitoring control monitors the stop of the motor caused by braking. In the abnormality monitoring control, the control unit monitors that an abnormality related to the rotation of the motor has occurred when the sensor signal does not change for a prescribed determination time or more during the rotation control for controlling the motor to rotate.

2. The washing machine according to claim 1, wherein: The control unit controls the motor so that the rotational speed of the motor follows a desired target speed; In the abnormality monitoring control, when the difference between the rotational speed of the motor calculated based on the sensor signal during the rotation control for controlling the motor to rotate and the target speed is equal to or greater than a prescribed threshold speed, it is monitored that an abnormality related to the rotation of the motor has occurred.

3. The washing machine according to claim 1 or 2, wherein: It further comprises: An agitator rotatably provided inside the rotary tub; The control unit performs a weight monitoring control as the prescribed monitoring control. In this weight monitoring control, after the laundry is loaded into the rotary tub, the rotational speed of the rotary tub is calculated based on the sensor signal when the agitator rotates, and the amount of the laundry is determined based on the calculated rotational speed.

4. The washing machine according to any one of claims 1 to 3, wherein: The control unit performs an imbalance monitoring control as a prescribed monitoring control. In this imbalance monitoring control, when the rotary tub rotates during the dehydration process of dehydrating the laundry, the rotational speed of the motor is obtained based on the sensor signal, and an imbalance caused by the bias of the laundry in the rotary tub is monitored based on the variation of the obtained rotational speed.

5. The washing machine according to claim 4, wherein: The motor comprises: A rotor provided with a plurality of magnets, and a stator provided with the position sensor; The position sensor is a magnetic sensor.

6. The washing machine according to claim 4 or 5, wherein: In the imbalance monitoring control, the control unit monitors the imbalance based on not only the obtained rotational speed of the motor but also the current detected by the current detection unit.

7. The washing machine according to any one of claims 4 to 6, characterized in that in the unbalance monitoring control, the control unit extracts a signal of a frequency component corresponding to a variation during one rotation of the motor by performing digital filter processing on the obtained rotational speed of the motor, and monitors the unbalance based on the extracted signal of the frequency component.

Images