washing machine

Abstract

A washing machine is provided that accurately detects a wire break in a motor that rotates a drum and reduces the time required for wire break detection. The washing machine includes: a three-phase brushless DC motor that rotates the drum and drives a pulsator via a reduction gear; an inverter circuit that drives the motor using PWM control; a current detection unit that individually detects the three-phase current of the motor; a control unit that vector controls the motor via the inverter circuit; a wire break detection unit; and an abnormality processing unit. When the wire break detection unit detects a wire break, the unit stops the motor and issues an abnormality report. The wire break detection unit performs a smoothing process on the current value detected by the current detection unit while the motor is rotating the pulsator via the reduction gear. A wire break is detected when the difference between the current value of one phase and at least one of the other two phases remains below a predetermined value for a predetermined period of time.

Description

Technical Field

[0001] An embodiment of the present invention relates to a washing machine. Background Art

[0002] In washing machines, the following prior art technologies are used to detect wire breaks in the three-phase brushless DC motor (i.e., the motor) used to rotate the drum that holds laundry. The first prior art detects wire breaks based on the difference between the maximum and average input currents of the inverter circuit that drives the motor. The second prior art detects wire breaks based on the comparison of the current value of one of the three phases with the current values ​​of the other two phases after smoothing the phase currents of the motor that are detected individually.

[0003] A third prior art determines a wire break when the line voltage between each phase of the motor is above a reference value and the motor phase current is below a threshold value for a predetermined period of time. A fourth prior art improves detection accuracy by specifically energizing the motor when a wire break is suspected. A fifth prior art uses a comparator to quickly detect motor overcurrent caused by a momentary wire break.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 10-145960

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2009-61164

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2015-213666

[0009] Patent Document 4: Japanese Patent Application Laid-Open No. 2017-205286

[0010] Patent Document 5: Japanese Patent Application Laid-Open No. 2019-72175 Summary of the Invention

[0011] Problems that the invention will solve

[0012] The first prior art suffers from the problem that, even when no disconnection has occurred, the difference between the maximum and average input current values ​​increases when the load fluctuates significantly, making false detection more likely. The second prior art, however, requires smoothing the phase currents, resulting in a relatively long response time. Furthermore, it cannot detect momentary disconnections caused by partial disconnections or rotational shaking.

[0013] In the third prior art, phases are generated in the inter-line voltage and phase current according to the operating conditions and the like, and thus there is a problem that false sensing is likely to occur. The fourth prior art is not a method that can be carried out during actual operation, but is only a supplementary technology. In the fifth prior art, even when a disconnection occurs during the high-speed rotation of the motor, it is difficult for the motor current to increase, and thus there is a problem that the determination by the comparator becomes difficult.

[0014] Therefore, there is provided a washing machine that can accurately detect a disconnection of a motor that rotationally drives a rotatable drum and can shorten the time required for disconnection detection.

[0015] Means for Solving the Problem

[0016] The washing machine according to the embodiment includes: a rotatable drum that houses laundry; a pulsator that is rotatably provided inside the rotatable drum; a motor that is a three-phase brushless DC motor and rotationally drives the rotatable drum and rotationally drives the pulsator via a reduction gear; an inverter circuit of a PWM control method that drives the motor; a current detection unit that individually detects the currents of the three phases of the motor; a control unit that performs vector control (Japanese: ベクトル制御) on the motor via the inverter circuit; a disconnection detection unit that detects a disconnection of the motor; and an abnormality processing unit that stops the rotation of the motor and reports an abnormality when a disconnection is detected by the disconnection detection unit. The disconnection detection unit performs a smoothing process for smoothing the current value, the current value being the current value detected by the current detection unit during the period when the motor rotationally drives the pulsator via the reduction gear, and detects a disconnection when a state where the difference between the current value of one of the three-phase currents and at least one of the current values of the other two-phase currents becomes less than or equal to a specified value continues for a specified time.

[0017] Advantages of the Invention

[0018] According to the washing machine of the present invention, it is possible to accurately detect a disconnection of a motor that rotationally drives a rotatable drum and shorten the time required for disconnection detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. is a longitudinal sectional side view schematically showing a part of the configuration of the washing machine according to the first embodiment.

[0020] Figure 2 FIG. is a functional block diagram schematically showing the electrical structure of the washing machine centered on the control unit according to the first embodiment.

[0021] Figure 3 FIG. is a circuit diagram schematically showing the electrical structure of the washing machine according to the first embodiment.

[0022] Figure 4 This is a diagram schematically showing the structure of a stator of the electric motor according to the first embodiment.

[0023] Figure 5 It is a diagram schematically showing the structure of the rotor of the electric motor according to the first embodiment.

[0024] Figure 6 It is a diagram schematically showing the shape of water flow in the first embodiment.

[0025] Figure 7 1 is a timing chart schematically showing current values ​​of the three phases of the motor before and after the smoothing process according to the first embodiment is performed.

[0026] Figure 8 This is a flowchart showing the flow of disconnection detection in the second embodiment.

[0027] Description of Reference Numerals

[0028] In the accompanying drawings, 1 represents an inverter circuit, 7 represents a control circuit, 100 represents a washing machine, 104 represents a rotary tub, 108 represents a pulsator, and 113 represents a motor. DETAILED DESCRIPTION

[0029] Hereinafter, a plurality of embodiments will be described with reference to the accompanying drawings. In each embodiment, substantially the same configuration will be denoted by the same reference numerals and description thereof will be omitted.

[0030] (First embodiment)

[0031] Below, refer to Figures 1 to 7 , the first embodiment is described.

[0032] <Washing Machine Structure>

[0033] like Figure 1 As shown, washing machine 100 is elastically supported by elastic suspension mechanism 103 on a cylindrical water tub 102 with an open top and a bottom, within an outer casing 101 forming its outer shell. A rotary drum 104 with an open top and a bottom is rotatably mounted within tub 102. Rotary drum 104 accommodates laundry, allowing for both insertion and removal.

[0034] A reinforcing member 105 is provided at the bottom of rotary drum 104 to reinforce the bottom of rotary drum 104. Rotary drum 104 is configured to rotate about a vertical axis and serves as both a washing tub (washing operation, rinsing operation, and dehydration tub) during the dehydration operation. Specifically, washing machine 100 is a so-called vertical axis type washing machine, in which the central axis of rotation of rotary drum 104 extends vertically.

[0035] The rotary barrel 104 has a plurality of holes 106 on its peripheral wall. These holes 106 are through and can pass water and ventilation. Figure 1 Only a portion of the multiple holes 106 are shown. A synthetic resin gimbal 107, enclosed with a liquid such as salt water, is mounted on the top of the rotary drum 104. Inside the rotary drum 104, specifically at its inner bottom, a pulsator 108, made of synthetic resin, is rotatably mounted as an agitator. A drainage path 109 is provided at the bottom of the water storage tub 102. A drain valve 110 is provided in the drainage path 109. When the drain valve 110 is opened, the water in the water storage tub 102 is drained to the outside of the machine. Furthermore, a steam trap 111 for water level sensing is provided at the bottom of the water storage tub 102.

[0036] A drive mechanism 112 is located in the center of the lower portion of the water receiving tub 102. This mechanism includes, among other things, a motor 113 and a clutch mechanism 112a, which serves as a clutch and reduction gear. During the washing or rinsing cycle, the drive mechanism 112 transmits rotational force to the pulsator 108 via the clutch mechanism 112a. Therefore, during the washing or rinsing cycle, the rotary tub 104 is not rotated; only the pulsator 108 is driven. During this cycle, the pulsator 108 rotates at a 1 / 5 reduction in speed, alternating between forward and reverse rotation.

[0037] Furthermore, during the spin cycle, the drive mechanism 112 transmits the rotational force of the motor 113 to the pulsator 108 and the rotary tub 104 via the clutch mechanism 112a. Therefore, during the spin cycle, the pulsator 108 and the rotary tub 104 rotate integrally. At this time, the rotary tub 104 is rotated without deceleration. Thus, the motor 113 rotates the rotary tub 104 and, via the reduction gear, the pulsator 108.

[0038] A top cover 114 is provided at the top of the outer case 101. A cover 115, for example, of a folding type, is provided on the top cover 114 so as to be openable and closable, for opening and closing the laundry inlet and outlet. In addition, a tub cover (not shown) is installed on the top of the water tub 102 so as to be openable and closable. An operation panel 116 is provided at the front of the top cover 114. A control unit 117 for controlling the overall operation of the washing machine 100 is arranged on the back side of the operation panel 116. A water supply mechanism 118 for supplying water from a water source into the water tub 102 is provided at the rear inside the top cover 114. The water supply mechanism 118 includes a water supply valve (not shown), a water supply path (not shown) connected to the water tub 102, and the like. The control unit 117 controls the water supply to the water tub 102 by controlling the opening and closing of the water supply valve.

[0039] <Control unit>

[0040] like Figure 2 As shown, control unit 117 is primarily composed of, for example, a microcomputer and has the function of controlling the overall operation of washing machine 1. Control unit 117 receives input signals from, for example, operation input unit 116a included in operation panel 116, water level sensor 121 for detecting the water level in tub 102, safety switch 122, rotation speed sensor 123 for detecting the rotation speed of motor 113, and rotation position sensor 9 for detecting the rotation position of a rotor included in motor 113.

[0041] Safety switch 122 is operated by a safety lever (not shown). This lever is positioned to hang from the bottom of top cover 114, positioned between the outer circumference of tub 102 and the inner surface of outer case 101. Safety switch 122 is operated as tub 102 shakes, causing the outer surface of tub 102 to contact the safety lever. This allows detection of significant shaking of tub 102. Based on these input signals and a pre-established control program, control unit 117 controls display unit 116b included in operation panel 116, water supply valve 118a included in water supply mechanism 118, motor 113, switching motor 124, and the like.

[0042] The switching motor 124 is used to switch the clutch mechanism 112a and the drain valve 110 in a linked manner. Specifically, when the drain valve 110 is opened by the switching motor 124, the clutch mechanism 112a is switched so that the motor 113 rotates the pulsator 108 and the rotary drum 104 in unison. When the drain valve 110 is closed, the clutch mechanism 112a is switched so that the motor 113 rotates only the pulsator 108 independently. Alternatively, an electromagnetic solenoid may be used in place of the switching motor 124.

[0043] <Electrical Structure of a Washing Machine Control System>

[0044] Figure 3 This is a functional block diagram showing a drive control system for the motor 113. In this case, the control unit 117 includes an inverter circuit 1 that uses a PWM control method to drive the motor 113. PWM is an abbreviation for Pulse Width Modulation. The inverter circuit 1 is formed by connecting six IGBTs 2a to 2f, which are semiconductor switching elements, in a three-phase bridge configuration, and flywheel 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, and 113w of the motor 113, respectively. In this embodiment, as the motor 113, for example, an outer rotor type three-phase brushless DC motor is used.

[0045] The emitter of IGBT 2d on the lower arm side is grounded via shunt resistor 4a, a current sensing element, and further grounded via resistor 5a and capacitor 6a. The common connection point of resistor 5a and capacitor 6a is connected to A / D input 2 terminal of control circuit 7, a microcomputer, and to the input terminal of overcurrent detection circuit 8. The emitter of IGBT 2e on the lower arm side is grounded via shunt resistor 4b, a current sensing element, and further grounded via resistor 5b and capacitor 6b. The common connection point of resistor 5b and capacitor 6b is connected to A / D input 3 terminal of control circuit 7, and to the input terminal of overcurrent detection circuit 8.

[0046] The emitter of the IGBT 2f on the lower arm side is grounded via a shunt resistor 4c, serving as a current detection element, and further grounded via a resistor 5c and a capacitor 6c. The common connection point of the resistor 5c and the capacitor 6c is connected to the A / D input 4 terminal of the control circuit 7 and to the input terminal of the overcurrent determination circuit 8. The overcurrent determination circuit 8 comprises three comparators and is configured to independently determine the currents of the three phases. The output signal of the overcurrent determination circuit 8 serves as an emergency stop signal based on overcurrent detection. When the emergency stop signal is input via the emergency stop input terminal, the control circuit 7 stops outputting the PWM signal to the inverter circuit 1.

[0047] Motor 113 is equipped with a rotational position sensor 9 that detects the rotational position of the rotor. Rotational position sensor 9 is a magnetic sensor, such as a Hall effect IC, and outputs a sensor signal, a digital signal corresponding to the rotational position detection result. The sensor signal output from rotational position sensor 9 is input to the sensor input terminal of control circuit 7 via NOT gate 10. The output terminal of NOT gate 10 is grounded via capacitor 11.

[0048] A driving power supply circuit 12 is connected to the input side of the inverter circuit 1. The driving power supply circuit 12 performs voltage-doubling full-wave rectification on a 100V AC power supply 13 using a full-wave rectifier circuit 14 comprised of a diode bridge and two capacitors 15a and 15b connected in series, supplying a DC voltage of approximately 280V to the inverter circuit 1. A first power supply circuit 16 steps down the approximately 280V driving power supplied to the inverter circuit 1 to generate a 15V power supply, which is then supplied to a drive circuit 17, a high-voltage driver 19, and a third power supply circuit 20 that drive the motor 113.

[0049] Second power supply circuit 18 is a three-terminal regulator that steps down the drive power supply to generate a 5V control power supply, supplying it to control circuit 7, rotational position sensor 9, and the like. High-voltage driver 19 is configured to drive IGBTs 2a-2c on the upper arm side of inverter circuit 1. Third power supply circuit 20 generates a 5V power supply from the 15V power supply generated by first power supply circuit 16 and supplies this power supply to overcurrent detection circuit 8. A / D input 2, A / D input 3, and A / D input 4 of control circuit 7 are pulled up to the 5V power supply by resistor elements 21a, 21b, and 21c, respectively.

[0050] A series circuit of resistors 22a and 22b is connected between the output terminal of the drive power supply circuit 12, the positive DC bus of the inverter circuit 1, and ground. The common connection point is connected to the A / D input 1 terminal of the control circuit 7. The control circuit 7 detects the three-phase current flowing into the motor 113 based on the terminal voltages of the shunt resistors 4a, 4b, and 4c, and performs vector control to generate three-phase upper and lower PWM signals with sinusoidal voltage rates. The control circuit 7 outputs the PWM signals to the gates of the IGBTs 2a to 2f that make up the inverter circuit 1 via the drive circuit 17 and, on the upper side, the high-voltage driver 19. In this way, the control circuit 7 controls the operation of the drive circuit 17 to control the drive of the motor 113 by the inverter circuit 1, which is composed of the IGBTs 2a to 2f.

[0051] In the drive circuit 17, each input terminal for receiving each PWM signal is pulled down to ground potential by a resistor element 23. In the above configuration, bootstrap capacitors 24d, 24e, and 24f are connected between the emitters of the IGBTs 2d, 2e, and 2f on the lower arm side and the high-voltage driver 19, respectively. In the above configuration, bootstrap capacitors 24d-24f are charged as the IGBTs 2a-2f switch, thereby generating a power supply voltage used by the high-voltage driver 19 to drive the gates of the IGBTs 2a-2c on the upper arm side. In the above configuration, a voltage of approximately 280V is applied to the windings 113u, 113v, and 113w of the motor 113, and a current of approximately 5-10A flows through them.

[0052] Thus, in this embodiment, the control circuit 7 functions as a current detection unit that individually detects the currents of the three phases of the motor 113, and also functions as a control unit that performs vector control of the motor 113 via the inverter circuit 1. Furthermore, in this embodiment, the control circuit 7 functions as a disconnection detection unit that detects disconnection of the motor 113, and also functions as an abnormality processing unit that performs operations described below. The specific functions of the disconnection detection unit of the control circuit 7 are described below.

[0053] That is, the control circuit 7 performs a smoothing process to smooth the three-phase current value of the motor 113, wherein the current value is the current value detected during the period when the motor 113 rotates the impeller 108 via the reduction gear, and a disconnection is detected when the current value of one phase of the three-phase current is compared with the current value of at least one of the other two phases, and the difference between them becomes less than a specified value for a specified time. The disconnection detection performed by the control circuit 7 is implemented when the speed of the motor 113 stabilizes after starting. Specifically, the control circuit 7 detects a disconnection as described above when the speed of the motor 113 is above a specified threshold speed. In addition, the threshold speed is set to 500 rpm, for example.

[0054] Specifically, the smoothing process described above is performed as follows. Specifically, the control circuit 7 smoothes the detected three-phase current values ​​of the motor 113 by calculating a moving average. In this case, the duration of the moving average is set to an integer multiple of the current variation cycle accompanying the rotation of the motor 113. In this embodiment, the duration of the moving average is set to 10 times the current variation cycle, that is, 10 cycles of the current. Furthermore, the control circuit 7 detects a wire break when the output voltage of the inverter circuit 1 is above a specified voltage and all the current values ​​of the three phases of the motor 113 are below a specified value.

[0055] Furthermore, in this embodiment, the control circuit 7 functions as an overcurrent sensor that senses an overcurrent condition in which an excessive current is flowing through the motor 113 when the current flowing through the motor 113 exceeds a predetermined determination current, and also functions as a rotation abnormality sensor that senses abnormal rotation of the motor 113 when the rotation speed of the motor 113 is less than a predetermined determination speed. The function of the control circuit 7 as the abnormality reporting unit is specifically described below.

[0056] Specifically, if the control circuit 7 detects a wire break through its function as a wire break detector, it stops the rotation of the motor 113 and issues an abnormality report. The abnormality report is a process that notifies the user of an abnormality via the display unit 116b of the operation panel 116 and a buzzer (not shown). Furthermore, if the control circuit 7 detects an overcurrent condition through its function as an overcurrent sensor, or a rotation abnormality through its function as a rotation abnormality sensor, it also stops the rotation of the motor 113 and issues the aforementioned abnormality report.

[0057] <Electric Motor Structure>

[0058] As a specific structure of the motor 113, for example, Figure 4 as well as Figure 5 The motor 113 has the following structure: Figure 4 The stator 31 shown in FIG. The stator 31 is a structure in which the stator core and the stator winding are integrated by using molded resin. In this case, 18 slots 32 are provided at equal intervals throughout the stator 31. That is, the stator 31 has an 18-slot structure. Figure 4 In FIG, only a portion of the groove 32 is shown.

[0059] In addition, the electric motor 113 has Figure 5 The rotor 33 shown in FIG. The rotor 33 is constructed by integrating a frame, a rotor core, and a plurality of magnets 34 using molded resin. In this case, twelve permanent magnets, or magnets 34, are arranged at equal intervals around the rotor 33. In other words, the rotor 33 has a twelve-pole structure.

[0060] <Water flow shape>

[0061] In the washing machine 100 constructed as described above, during the washing process or the rinsing process, that is, during the period when the motor 113 rotates the pulsator 108 via the reduction gear, the water flow in the tub 102 is as follows: Figure 6 In addition, Figure 6 In the chart, the vertical axis represents the rotational speed of motor 113, and thus the flow pattern of water within tub 102. Zero is the boundary, with the upper side representing the forward direction and the lower side representing the reverse direction. That is, as the rotational speed of motor 113 increases in the forward direction, the flow pattern also increases in the forward direction. At this point, the rotational speed of motor 113 gradually increases to the specified speed over approximately 0.2 seconds, continues in this state for approximately 0.8 seconds, and then decreases to 0 rpm.

[0062] Then, as the rotation speed of motor 113 increases in the reverse direction, the water flow pattern also increases in the reverse direction. At this point, the rotation speed of motor 113 gradually increases to the specified speed over approximately 0.2 seconds, and this state lasts for approximately 0.8 seconds before decreasing to 0 rpm. Thus, in the washing machine 100 configured as described above, while motor 113 is rotating pulsator 108 via the reduction gear, the water flow pattern in tub 102 repeats forward and reverse rotation every approximately one second.

[0063] Next, refer to Figure 7 The specific processing contents related to the disconnection detection performed by the control circuit 7 having the above-mentioned configuration will be described with reference to the timing diagram of FIG.

[0064] In this case, during the washing process, while the rotational speeds of the motor 113 and the pulsator 108 are constant at the stable rotational speeds during washing, a situation is assumed where the V-phase winding 113v of the motor 113 is momentarily disconnected for 0.3 seconds. In this embodiment, the stable rotational speeds during washing are 850 rpm for the motor 113 and 170 rpm for the pulsator 108.

[0065] like Figure 7 As shown in (a), (b), and (c), the currents Iu, Iv, and Iw flowing through the windings 113u, 113v, and 113w of the motor 113 are AC currents, so the values ​​cannot be determined directly using the detected current values. Therefore, the control circuit 7 performs absolute value processing on the detected three-phase current values, and then calculates the moving average value over 10 cycles of the motor current to perform smoothing processing. The smoothed values ​​of the detected currents Iu, Iv, and Iw obtained in this way are shown in FIG. Figure 7 As shown in (d), it becomes a constant value with little fluctuation.

[0066] In addition, in the following description and Figure 7 In the example, the smoothed values ​​of the detected currents Iu, Iv, and Iw are referred to as average currents Iua, Iva, and Iwa, respectively. Figure 7 In (d), the solid line shows the average current Iua, the dashed line shows the average current Iva, and the dotted line shows the average current Iwa. In this case, if the V-phase winding 113v is momentarily disconnected, the current Iv becomes zero. As a result, the average current Iva begins to decrease toward zero from the aforementioned constant value, reaching zero approximately 0.1 seconds after the point in time when the current Iv reaches zero.

[0067] Afterward, when the momentary disconnection in V-phase winding 113v is resolved, current Iv returns to its stable value. Consequently, average current Iva begins to rise from 0 toward the aforementioned constant value, reaching the aforementioned constant value approximately 0.1 seconds after current Iv reaches its stable value. In contrast, average currents Iua and Iwa remain unchanged at the aforementioned constant values. Thus, control circuit 7 compares average current Iva with either or both average currents Iua and Iwa, and can detect a disconnection in V-phase winding 113v if the difference between the average currents Iva and Iwa remains below a predetermined value for a predetermined period of time.

[0068] According to the present embodiment described above, the following effects can be obtained.

[0069] In the washing machine 100 of this embodiment, the motor 113 rotates the drum 104 and also rotates the pulsator 108 via the reduction gear. In this configuration, the control circuit 7 that controls the driving of the motor 113 performs a smoothing process on the three-phase current values ​​detected while the motor 113 is rotating the pulsator 108 via the reduction gear. A wire break is detected when the difference between the current value of one of the three-phase currents and the current value of at least one of the other two phases remains below a predetermined value for a predetermined period of time.

[0070] With this configuration, the time required for the smoothing process can also be significantly shortened compared to the second prior art method for smoothing three-phase current values. This is because, in this case, the rotational speed of motor 113, and therefore the frequency of the current flowing in motor 113, during the period when pulsator 108 is driven by the reduction gear is significantly higher than the frequency of the current flowing in motor 113 during the period when rotary drum 104 is driven by the reduction gear without the reduction gear. Therefore, with this configuration, the time required for the smoothing process to smooth the current value of motor 113 is significantly shortened compared to the time required for the smoothing process in the second prior art method, which does not include a reduction gear.

[0071] Therefore, according to this embodiment, a wire break in the motor 113 that rotates the rotary drum 104 can be detected with high accuracy, and the time required for wire break detection can be shortened. Furthermore, according to this embodiment, the time required for wire break detection is shortened as described above, that is, the sensing speed during wire break detection is increased, making it possible to detect momentary wire breaks such as those caused by partial wire breakage and rotational jitter.

[0072] If a wire break occurs in the motor 113, the rotation speed of the motor 113 decreases, so a method of detecting a wire break based on the rotation speed of the motor 113 can also be considered. However, this wire break detection has the following problems. That is, even if the motor 113 breaks, it will temporarily rotate due to inertia. This rotation under inertia will be particularly obvious in a structure with a reduction gear as in the present embodiment. Therefore, in the method of detecting a wire break based on the rotation speed, the wire break cannot be detected quickly, and in addition, it cannot cope with instantaneous wire breaks. In contrast, the wire break detection based on the smoothed three-phase current value of the control circuit 7 according to the present embodiment can improve the accuracy of wire break detection on the basis of being able to detect the wire break more quickly, and thus can also cope with instantaneous wire breaks, compared to the method of detecting a wire break based on the rotation speed.

[0073] The control circuit 7 detects a wire break when the output voltage of the inverter circuit 1 is above a specified voltage and the current values ​​of the three phases of the motor 113 are all below a specified value. In this way, it is not limited to a wire break in only one of the three phases of the motor 113, and it is also possible to detect wire breaks in two or more phases. In addition, the control circuit 7 smoothes the detected current values ​​of the three phases of the motor 113 by calculating a moving average, and the time of the moving average is set to an integer multiple of the cycle of change of the current accompanying the rotation of the motor 113. In this way, the time required for smoothing the current values ​​of the three phases is suppressed to a shorter time, and the fluctuation of the current value after the moving average is suppressed to a smaller value, thereby further improving the accuracy of wire break detection.

[0074] In the above configuration, if only one of the three phases of motor 113 is disconnected in a high rotational speed range, the currents of the other two phases are unlikely to increase rapidly due to, for example, induced voltages hindering the operation of inverter circuit 1. This makes it difficult to perform a determination based on the motor current. Therefore, in this embodiment, disconnection detection based on the three-phase current values ​​smoothed by control circuit 7 is performed after motor 113 is started and its rotational speed stabilizes. Specifically, control circuit 7 detects disconnection as described above when the rotational speed of motor 113 is above a predetermined threshold speed, that is, when the rotational speed of motor 113 is in a high rotational speed range.

[0075] In this way, when the rotational speed of motor 113 is relatively high, a wire break in only one of the three phases of motor 113 can be detected with high accuracy. Furthermore, control circuit 7 functions as an overcurrent sensor that senses an overcurrent condition, indicating excessive current flowing through motor 113, when the current flowing through motor 113 exceeds a predetermined threshold current. When an overcurrent condition is detected, motor 113 is stopped and an abnormality report is issued, similar to when a wire break is detected. This provides the following advantages.

[0076] That is, when the rotation speed of the motor 113 is less than a predetermined threshold rotation speed, that is, when the rotation speed of the motor 113 is in a relatively low range, the line break detection based on the three-phase current values ​​after smoothing by the control circuit 7 is not performed. However, in this case, if only one of the three phases of the motor 113 is broken, the currents of the other two phases increase sharply, and an overcurrent state is detected. As a result, even when the rotation speed of the motor 113 is in a relatively low range, a line break of only one phase can be reliably detected.

[0077] If a wire break occurs in two or more of the three phases of motor 113, motor 113 will not rotate and will soon stop. Therefore, control circuit 7 functions as a rotation abnormality sensor that detects abnormal rotation of motor 113 when the rotation speed of motor 113 is less than a predetermined determination speed. When a rotation abnormality is detected, motor 113 stops rotating and an abnormality report is issued. In this way, when the rotation speed of motor 113 is in either a low range or a high range, the detection is not limited to a wire break in only one of the three phases of motor 113, and wire breaks in two or more phases can also be detected.

[0078] (Second embodiment)

[0079] Below, refer to Figure 8 A second embodiment will be described.

[0080] In this embodiment, the processing contents related to disconnection detection in the control circuit 7 are changed compared to the first embodiment. The control circuit 7 of this embodiment performs, for example, Figure 8 Processing of the content as shown. Figure 8 As shown, in step S100, abnormality detection is performed. Abnormality detection includes detection of instantaneous disconnection, overcurrent, overvoltage, and rotation failure, all based on smoothed three-phase current values. After step S100, the process proceeds to step S200, where it is determined whether an abnormality has been detected multiple times, for example, three times in a row.

[0081] Here, if an abnormality is not detected multiple times in a row, the result is "No" in step S200, and the process returns to step S100. In contrast, if an abnormality is detected multiple times in a row, the result is "Yes" in step S200, and the process proceeds to step S300. In step S300, it is determined that an abnormality such as a momentary wire break has occurred in motor 113, and the rotation of motor 113 is stopped. After executing step S300, the process proceeds to step S400, where a control is performed to flow a predetermined inspection current through motor 113, and wire break detection is performed for this inspection current. This step S400 is a process for detecting a complete wire break.

[0082] After executing step S400, the process proceeds to step S500 to determine whether a wire break has been detected. If a wire break has not been detected, the result in step S500 is "No," and the process proceeds to step S600. In step S600, an abnormality cause reporting process is implemented, where the user reports the cause of the detected abnormality. The abnormality cause may be a momentary wire break, overcurrent, overvoltage, or rotational failure, as described above. In contrast, if a wire break has been detected, the result in step S500 is "Yes," and the process proceeds to step S700.

[0083] In step S700, a complete disconnection is determined to have occurred in motor 113, and a complete disconnection notification process is performed to notify the user of the complete disconnection. After executing steps S600 or S700, the process ends. The disconnection detection method of this embodiment prevents false detection of a disconnection when none actually exists, and reliably detects a disconnection when one does occur, thereby improving safety.

[0084] (Other embodiments)

[0085] The present invention is not limited to the embodiments described above and in the drawings, but can be arbitrarily modified, combined, or expanded without departing from the spirit and scope of the present invention.

[0086] The numerical values ​​and the like shown in the above-mentioned embodiments are merely examples and are not limiting.

[0087] As a specific method for comparing the current value of one phase among the three-phase currents with the current values ​​of the other two phases, the control circuit 7 can also compare the current value of one phase among the three-phase currents with the total current value of the three phases.

[0088] While various embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are intended to be included within the scope and spirit of the invention, and are also intended to be included in the invention as described in the claims and their equivalents.

Claims

1. A washing machine, characterized in that: have: Rotate the barrel to store clothes; a pulsator rotatably disposed inside the rotary tub; The motor is a three-phase brushless DC motor, which drives the rotary drum to rotate and drives the pulsator to rotate via a reduction gear; A PWM controlled inverter circuit drives the electric motor; a current detecting unit for individually detecting currents of the three phases of the motor; a control unit that performs vector control on the electric motor via the inverter circuit; a wire breakage detection unit for detecting a wire breakage of the motor; as well as an abnormality processing unit that stops the rotation of the motor and issues an abnormality report when the disconnection detection unit detects a disconnection; The disconnection detection unit performs a smoothing process on the current value, wherein the current value is the current value detected by the current detection unit during the period when the motor drives the impeller to rotate via the reduction gear, and a disconnection is detected when the difference between the current value of one phase of the three-phase current and the current value of at least one of the other two phases becomes less than a specified value for a specified period of time.

2. The washing machine according to claim 1, wherein The wire breakage detection unit detects a wire breakage when an output voltage of the inverter circuit is equal to or higher than a predetermined voltage and current values ​​of all three phases of the electric motor are equal to or lower than predetermined values.

3. The washing machine according to claim 1 or 2, characterized in that: The disconnection detection unit smoothes the current value detected by the current detection unit by calculating a moving average. The time period of the moving average value is set to an integral multiple of a cycle of change in the current accompanying the rotation of the motor.

4. The washing machine according to any one of claims 1 to 3, characterized in that The wire breakage detection unit detects a wire breakage when the rotation speed of the electric motor is equal to or higher than a predetermined threshold rotation speed.

5. The washing machine according to claim 4, characterized in that have: an overcurrent sensing unit configured to sense an overcurrent state in which an excessive current flows through the motor when the current of the motor is greater than a predetermined determination current; and The rotation abnormality sensing unit senses that the rotation of the motor is abnormal when the rotation speed of the motor is lower than a predetermined determination speed. The abnormality processing unit also stops the rotation of the motor and issues the abnormality report when the overcurrent sensor detects the overcurrent state or the rotation abnormality sensor detects the rotation abnormality.

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