JP7324971B2 - washing machine - Google Patents

Description

The present disclosure relates to washing machines.

Patent Literature 1 discloses a washing machine that detects the temperature of windings of a stator with a thermistor.

The washing machine in Patent Literature 1 includes a water tank, a drum rotatably arranged inside the water tank, a motor for rotating the drum, and a control circuit for controlling the motor and the like. A motor is composed of a rotor having a ring-shaped permanent magnet and a stator having three-phase windings, and a thermistor, which is temperature detecting means, is arranged near the windings of the stator. The control circuit senses the temperature of the stator windings from the thermistor voltage.

JP-A-11-239688

However, parts such as thermistors are expensive, and there is a problem that the manufacturing cost is high.

The present disclosure provides a washing machine that improves motor safety with an inexpensive configuration.

A washing machine according to the present disclosure includes a rotating tub, a motor that rotates the rotating tub, an inverter circuit that converts direct current to alternating current and drives the motor, and a current detection unit that detects current flowing through the motor. a low-pass filter unit that performs low-pass filter processing on the current detected by the current detection unit and outputs the low-pass filtered value as a current value after processing; and an overload detection unit that detects an overload state of the motor. and a control unit that transmits a motor drive command to the inverter circuit and controls the motor through the previous inverter circuit. The overload detection unit determines that the motor is in an overload state when a predetermined time elapses in a state where the processed current value output from the low-pass filter unit is equal to or greater than a first value. , when the current value after the processing is a second value smaller than the first value, the overload state is released, and the control unit, based on the determination result of the overload detection unit, It controls the rotational drive of the motor.

The washing machine according to the present disclosure improves motor safety with an inexpensive configuration.

1 is a longitudinal sectional view showing a schematic configuration of a washing machine according to Embodiment 1; Block diagram showing the circuit configuration of the washing machine Characteristic diagram of motor winding temperature at each current value of the motor of the same washing machine Flowchart of overload state detection processing of the motor of the washing machine Flowchart of inverter control processing for the motor of the washing machine Relationship diagram between motor current (after low-pass filter processing) and motor drive command of the same washing machine Flowchart of Inverter Control Processing for Motor of Washing Machine in Embodiment 2

Hereinafter, embodiments will be described in detail with reference to the drawings. It should be noted that the present invention is not limited by the accompanying drawings and the following description.

(Embodiment 1)
Embodiment 1 will be described below with reference to FIGS. 1 to 6. FIG.

(Basic configuration of washing machine)
1 is a longitudinal sectional view showing a schematic configuration of a washing machine according to Embodiment 1. FIG.

As shown in FIG. 1, inside a washing machine body 1, a bottomed cylindrical water tub 2 is elastically supported by a suspension structure (not shown). The water tank 2 is supported with its axial direction inclined downward from the front side toward the back side. A bottomed cylindrical drum 3 is rotatably disposed inside the water tank 2 . The inner wall surface of the drum 3 is formed with a plurality of water passage holes 6 for passing washing water inside and outside the drum 3 and a plurality of agitating protrusions (not shown) for agitating the clothes.

A doughnut-shaped fluid balancer 15 is arranged on the front side of the drum 3 . The fluid balancer 15 is divided into a plurality of storage chambers (not shown) by a plurality of partition plates provided in the circumferential direction, and communication holes are formed in the respective partition plates. Inside the fluid balancer 15, a liquid with a large specific gravity such as calcium chloride is stored. Liquid can move from one storage chamber to the next via the communication holes. If the laundry inside the drum 3 is biased during the washing operation, an eccentric load is generated on the drum 3 . By moving to the opposite side of the eccentric load, the liquid corrects the deviation of the center of gravity and reduces the vibration noise of the drum 3 .

A clothes entrance 4 leading to an open end of a drum 3 is formed on the front side of the washing machine main body 1, and the clothes entrance 4 is covered with a door 5 so as to be openable and closable. A user can put laundry in and out of the drum 3 through the laundry entrance 4 with the door 5 open. An operation display panel 10 serving as an input setting section 25 (see FIG. 2) is provided above the clothes entrance 4 in the upper front portion of the washing machine main body 1 . A user can set a desired driving course by operating the operation display panel 10 .

The motor 7 is arranged below the water tank 2 . The motor 7 is connected via a pulley 14 and a belt 16 to a rotation center shaft 17 provided on the lower bottom of the drum 3 . The rotational driving force of the motor 7 is transmitted to the drum 3 via the pulley 14 and the belt 16 to rotate the drum 3 forward or backward.

The water inlet line 8 is connected to the upper portion of the water tank 2 , and the drain line 9 is connected to the lower portion of the water tank 2 . A water supply valve 27 and a water discharge valve 28 are provided in the water supply line 8 and the water discharge line 9 so as to be able to be opened and closed. By opening the water supply valve 27 and the water discharge valve 28 respectively, water is supplied to and drained from the water tank 2 .

(Configuration of motor drive device)
2 is a block diagram showing a circuit configuration of the washing machine according to Embodiment 1. FIG.

As shown in FIG. 2, a circuit for driving the motor 7 is provided with a rectifier 21, a choke coil 22, and a smoothing capacitor . The AC voltage of commercial power source 20 is rectified by rectifier 21 . The rectified AC power is converted into a DC voltage by a smoothing circuit consisting of a choke coil 22 and a smoothing capacitor 23 . Therefore, the converted DC voltage is applied to the inverter circuit 24 .

The inverter circuit 24 is composed of a three-phase full-bridge inverter circuit composed of six power switching semiconductors and antiparallel diodes. In this embodiment, an intelligent power module (hereinafter referred to as an IPM) containing an insulated gate bipolar transistor (IGBT), an anti-parallel diode, a drive circuit for the diode, and a protection circuit is used. A motor 7 is connected to an output terminal of the inverter circuit 24 . Further, the inverter circuit 24 controls the operation of the water supply valve 27, the drain valve 28, the blower fan 12, and the heat pump 29 by the load driving section 26 based on the operation instruction and monitoring information.

Motor 7 is a brushless motor. The motor 7 includes a permanent magnet forming a rotor, a stator, and a rotor position detector 30 . The rotor position detector 30 is composed of three Hall ICs, a Hall IC 30a, a Hall IC 30b, and a Hall IC 30c. The Hall IC 30a, Hall IC 30b, and Hall IC 30c detect a position output reference signal for every 60 electrical degrees from the relative position (rotor position) between the permanent magnet and the stator.

The current detection means in this embodiment is composed of a shunt resistor (not shown) provided in the inverter circuit 24 . The current detection means detects motor currents Iu, Iv and Iw of the motor 7 .

The control unit 31 includes a microcomputer, an inverter control timer (PWM timer) built in the microcomputer, a high-speed A/D conversion circuit, a memory circuit (ROM, RAM), and the like. The control unit 31 detects the electrical angle from the output signal of the rotor position detection unit 30, and performs a three-phase/two-phase dq conversion that resolves the current component Id corresponding to the magnetic flux and the current component Iq corresponding to the torque. 2-phase/3-phase dq inverse conversion is performed to convert the voltage component Vd and the voltage component Vq corresponding to the torque into the 3-phase motor drive control voltages Vu, Vv, and Vw. PWM-controls the switching of the IGBTs of the drive circuit 32 . Thereby, the control unit 31 controls the energization of the windings 7a, 7b, and 7c, which are the three-phase windings of the stator, and rotates the motor 7 at the required rotation speed.

In this embodiment, the microcomputer of the control section 31 serves as the low-pass filter processing section 33 and the overload detection section 34 . Detailed operations of the low-pass filter processing unit 33 and the overload detection unit 34 will be described later.

(Basic operation of washing operation)
The user opens the door 5, loads laundry and detergent into the drum 3, and operates the operation display panel 10, which is the input setting section 25, to start operation. When the operation starts, the controller 31 opens the water supply valve 27 to fill the water tank 2 with water. When the water reaches the predetermined water level, the control unit 31 closes the water supply valve 27 and starts the washing operation.

In the washing operation, the controller 31 rotates the drum 3 by rotating the motor 7 . As the drum 3 rotates, the laundry stored in the drum 3 is lifted in the rotating direction by the stirring projections, dropped from an appropriate height position, and stirred. Thus, in the washing operation, dirt is removed by pounding the laundry by picking it up and dropping it.

After a predetermined period of time has elapsed in the washing operation, the controller 31 opens the drain valve 28 and drains the dirty washing liquid from the drain pipe 9 . Subsequently, the control unit 31 dehydrates the washing liquid contained in the laundry by the dehydration operation of rotating the drum 3 at high speed.

(Relationship between motor current value and motor winding temperature)
When the drum 3 is overfilled with clothes, the clothes are twisted or entangled while the drum 3 is rotating, and the motor 7 is subjected to an excessive load. In a state in which an excessive load is applied to the motor 7, that is, in a motor overload state, the current value flowing through the motor 7, that is, the motor current value becomes higher than the motor current value during normal washing operation.

FIG. 3 is a characteristic diagram of the motor winding temperature at each current value of the motor of the washing machine according to the first embodiment.

The motor winding temperature is the temperature of the three-phase windings 7a, 7b, and 7c. In FIG. 3, the horizontal axis indicates the operating time, and the vertical axis indicates the motor winding temperature, showing changes in the motor winding temperature at each current value. Each current value is set to a predetermined value so that motor current A, motor current B, motor current C, and motor current D decrease in this order.

In general, the motor winding temperature rises in proportion to the square of the motor current value, and the motor winding temperature saturates after a certain period of time. If this saturation temperature exceeds the heat-resistant temperature of the motor windings, the motor windings may burn out. Therefore, it is necessary to control the motor current value so that the motor winding temperature does not exceed the heat-resistant temperature.

In the present embodiment, the current value at which the winding saturation temperature may exceed the heat resistance temperature of the motor winding is experimentally measured in advance, and a predetermined threshold value is set based on the current value. A motor overload condition is defined when the motor current value exceeds a predetermined threshold for a predetermined period of time.

(Overload state detection processing and inverter control processing)
FIG. 4 is a flow chart of overload state detection processing for the motor of the washing machine according to Embodiment 1, and FIG. 5 is a flow chart of inverter control processing for the motor of the washing machine.

In the washing operation, the control unit 31 starts the overload state detection process (S101) and starts the inverter control process shown in FIG. Note that the two processes are performed in parallel and independently, and are repeatedly performed at respective time intervals.

First, overload state detection processing will be described.

As shown in FIG. 4, when the overload detection unit 34 starts the overload state detection process (S101), the motor current value is low-pass filtered (S102).

In the low-pass filter processing in this embodiment, the amount of change between the previous motor current value and the current motor current value is calculated, the amount of change is reduced at a constant rate, and added to the previously detected current. These processes are arithmetically processed by the low-pass filter processing section 33, which is a microcomputer. Generally, it is known that the value of the current that flows when starting the motor momentarily becomes a large current value and then gradually converges to a constant value. By performing low-pass filter processing, it is possible to remove the component due to the input current from the measured value of the motor current value, and suppress erroneous detection of an overload state caused by a momentary large current flow. Note that the time constant of the low-pass filter is set to a time (for example, 10 seconds) substantially equal to the ON time of the motor drive.

Next, the overload detection unit 34 compares the motor current value after the low-pass filter processing with the threshold α to determine whether the motor is overloaded (S103). In S103, if the motor current value is less than α (S103, No), or if the motor current value is greater than or equal to α and the predetermined time t1 has not elapsed, the overload state detection process is terminated (S107). This prevents erroneous detection of the motor overload state when the motor current value momentarily becomes equal to or greater than α.

In S103, when the predetermined time t1 has passed while the motor current value is equal to or greater than α (S103, Yes), the overload detection unit 34 sets the motor overload state, that is, the motor is in the overload state. (S104).

As described above, in a motor overload condition, the motor winding temperature may exceed the heat-resistant temperature. Therefore, the motor windings must be allowed to cool until the motor current value after low-pass filtering becomes equal to or less than a predetermined value. In the present embodiment, a threshold value β, which is one third of the threshold value α, is set.

The overload detection unit 34 compares the motor current value after low-pass filtering with the threshold value β (S103). In S105, if the motor current value exceeds the threshold value β (S105, No), the overload state detection process is terminated (S107).

In S105, if the motor current value is equal to or less than the threshold value β (S105, Yes), the motor overload state is cleared, that is, the determination that the motor is in the overload state is canceled (S106). After that, the overload state detection process is ended (S107).

Next, inverter control processing will be described.

As shown in FIG. 5, the controller 31 starts inverter control processing (S201). The control unit 31 causes the drive circuit 32 to PWM-control the switching of the IGBT by issuing a motor drive command. (S202). Thereby, the motor 7 rotationally drives the drum 3 based on the motor drive command.

In S203, if the motor overload state is set (S203, Yes), the control unit 31 causes the drive circuit 32 to stop PWM output (S204). After that, the inverter control process is terminated (S205). If the motor overload condition is not set (S203, No), the inverter control process is terminated (S205).

Next, the characteristics of the motor current value (after low-pass filter processing) and the motor drive command in this embodiment will be described.

FIG. 6 is a diagram showing the relationship between the motor current (after low-pass filtering) and the motor drive command of the washing machine according to the first embodiment. The horizontal axis is the operation time, the left vertical axis is the motor current value after low-pass filtering, and the right vertical axis is the motor drive command.

The agitation time limit during washing is one cycle of 10 seconds in the ON state and 1 second in the OFF state. At this time, the motor current value after the low-pass filter process increases while vibrating up and down when the stirring is ON, and gradually decreases when the stirring is OFF. When the motor overload state is set in the overload state detection process shown in FIG. 4, the PWM output is stopped in the inverter control process shown in FIG. Since the motor current does not flow during the period in which the PWM output is stopped, the motor current value after low-pass filter processing gradually decreases.

It is known that the motor current value after low-pass filtering takes longer to decrease as the motor current value increases. Therefore, when the motor current value is large, the time until the motor current value becomes equal to or less than the threshold value β becomes longer, and as a result, the period during which the motor drive is stopped becomes longer. As a result, even if the motor current value rises sharply before the predetermined time t1 elapses while the motor current value is equal to or greater than the threshold value α, the cooling time becomes longer according to the motor current value. Temperature can be lowered more reliably.

When the motor current value after the low-pass filter processing falls below the threshold value β, the motor overload state is cleared in the overload state detection process shown in FIG. Then, the PWM output is resumed in the inverter control process shown in FIG.

As described above, by detecting a motor overload state based on the motor current after low-pass filtering and suppressing the motor winding temperature within the heat-resistant temperature range, the safety function of the motor can be implemented at a lower cost than in the past.

(action, etc.)
The drum-type washing machine according to the present embodiment includes a drum 3, a motor 7 that rotates the drum 3, an inverter circuit 24 that converts direct current to alternating current and drives the motor 7, and a current that flows through the motor 7. a current detection unit that detects a current, a low-pass filter processing unit 33 that performs low-pass filtering on the current detected by the current detection unit and outputs the low-pass filtered value as a current value after processing, and an overload state of the motor 7. An overload detection unit 34 for detection and a control unit 31 for transmitting a motor drive command to the inverter circuit 24 and controlling the motor 7 through the inverter circuit 24 are provided.

The overload detection unit 34 determines that the motor 7 is overloaded based on the processed current value output from the low-pass filter processing unit 33, and the control unit 31 receives the determination result of the overload detection unit 34. , the rotational drive of the motor 7 is controlled.

As a result, an increase in motor winding temperature can be detected from a change in motor current value without providing a separate component such as a thermal fuse or a thermistor. Therefore, it is possible to suppress the motor winding temperature from excessively increasing, and realize the safety of the motor at a low cost.

Further, as in the present embodiment, the overload detection unit 34 detects that the motor 7 is in an overload state when a predetermined time has passed in a state in which the current value after processing is equal to or greater than the first value α. If it is determined that there is, and the current value after processing is a second value β that is smaller than the first value α, the motor overload state may be released.

As a result, the time from when it is determined that the motor 7 is overloaded and stopped until the motor current value falls below β becomes longer as the motor current value increases. Therefore, when there is a high possibility that the temperature of the windings will rise, it is possible to take a longer time for heat radiation, so that the safety of the motor can be realized at a low cost.

(Embodiment 2)
The washing machine according to the second embodiment differs from the washing machine 100 according to the first embodiment in inverter control processing during dehydration operation. Hereinafter, the second embodiment will be described using the same reference numerals for the same configurations as in the first embodiment.

FIG. 7 is a flowchart of inverter control processing for the motor of the washing machine according to the second embodiment.

The control unit 31 starts inverter control processing (S301). The control unit 31 determines whether or not a history of PWM output stop has been set, that is, whether or not a history of stopping due to a motor overload state in the previous inverter control process has been set (S302). If the PWM output stop history is set (S302, Yes), a motor driving command is transmitted so that the rotation speed of the motor 7 is decreased (S303). For example, when the dehydration speed is 1400 rpm and an overload state is detected, the dehydration speed is reduced to 1300 rpm in the next inverter control process.

In S304, the control unit 31 clears the PWM output stop history, that is, cancels the history of stopping due to the motor overload state in the previous inverter control process (S304).

In S305, the drive circuit 32 performs PWM output according to the motor drive command received from the control unit 31 (S305).

At step 306, the control unit 31 refers to the motor overload state (S306). If the motor overload condition is set (S306, Yes), the drive circuit 32 is made to stop the PWM output (307), and the PWM output stop history is set (S308). After that, the inverter control process is terminated (309). After a predetermined time has passed, the next inverter control process is started (S301).

By repeating the inverter control process (S301 to S309) described above, the rotation speed of the motor 7 is adjusted so that the motor current value becomes equal to or less than the overload current value.

In particular, in the dehydration operation, since the flux-weakening control is performed in accordance with the increase in the motor induced voltage, the motor current increases as the rotation speed increases. Therefore, by adjusting the rotation speed of the motor 7, it is possible to effectively suppress an excessive rise in the motor winding temperature.

(action, etc.)
The drum-type washing machine according to the present embodiment includes a drum 3, a motor 7 that rotates the drum 3, an inverter circuit 24 that converts direct current to alternating current and drives the motor 7, and a current that flows through the motor 7. a current detection unit that detects a current, a low-pass filter processing unit 33 that performs low-pass filtering on the current detected by the current detection unit and outputs the low-pass filtered value as a current value after processing, and an overload state of the motor 7. An overload detection unit 34 for detection and a control unit 31 for transmitting a motor drive command to the inverter circuit 24 and controlling the motor 7 through the inverter circuit 24 are provided. The overload detection unit 34 determines that the motor 7 is in an overload state based on the processed current value output by the low-pass filter processing unit 33, and the control unit 31 is in an overload state during the dehydration operation. In this case, the rotation speed of the motor 7 is decreased.

As a result, in the dehydration operation in which the motor current increases as the rotation speed rises, by adjusting the rotation speed of the motor 7, it is possible to effectively suppress an excessive rise in the motor winding temperature.

(Other embodiments)
As described above, Embodiments 1 and 2 have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this.

Therefore, other embodiments will be exemplified below.

In Embodiments 1 and 2, the drum-type washing machine has been described as an example of the washing machine. Any washing machine may be used as long as the rotary tub is driven to rotate by a motor. Therefore, the washing machine is not limited to a drum-type washing machine, and may be a vertical washing machine or a two-tub washing machine.

In the first and second embodiments, IGBTs have been described as an example of power switching semiconductors. The power switching semiconductor may comprise a metal oxide semiconductor field effect transistor (MOSFET) or the like.

In Embodiments 1 and 2, the shunt resistor has been described as an example of the current detection section. The current detector may use a method of measuring a DC current transformer or an AC current transformer from a low frequency containing DC current. In the case of a three-phase motor, a method may be used in which two phase currents are obtained and the remaining one phase is obtained from Kirchhoff's law (Iu+Iv+Iw=0).

In the first and second embodiments, as an example of the rotor position detection section, the rotor position detection section 30 that detects the rotor position based on the output reference signals H1 to H3 from the Hall IC has been described. The rotor position detector is not limited to one that uses a Hall IC. The rotor position detector may detect the rotor position by calculation from the motor phase current and the three-phase motor drive control voltage.

In Embodiments 1 and 2, arithmetic processing in the microcomputer has been described as an example of the low-pass filter section, but the present invention is not limited to this. A low-pass filter configuration may be implemented on the circuit using resistors and capacitors as the low-pass filter section. Further, in the first and second embodiments, as an example of low-pass filter processing, the amount of change between the previous motor current value and the current motor current value is calculated, and the amount of change is reduced at a constant rate to match the previously detected current. The combined configuration was explained. Low-pass filtering is not limited to this method. For example, a simple moving average value may be used.

In the first and second embodiments, the low-pass filtering process (S102) performed as part of the overload state detection process has been described as an example of the low-pass filtering process. The timing of performing the low-pass filtering process is not limited to step 102, and may be performed independently of the overload state detection process.

In Embodiments 1 and 2, the threshold value β, which is one third of the threshold value α, has been described as the reference value for determining that the motor is not overloaded. The reference value is not limited to one-third of the threshold α, as long as it can be determined that the motor is not overloaded.

In the first embodiment, as an example of controlling the rotational drive of the motor in the motor overload state, the example of stopping the driving of the motor 7 in the motor overload state has been described. The control of the rotational drive of the motor in the motor overload state is not limited to stopping the drive. For example, the stirring time period during washing may be changed to shorten the ON state time and lengthen the OFF state time.

In the first embodiment, as a method for controlling the rotational drive of the motor based on the determination result of the overload detector, the example of stopping the driving of the motor 7 in the motor overload state has been described. The method of controlling the rotational drive of the motor is not limited to stopping the driving of the motor 7 in the motor overload state, and may be stopping the washing operation. For example, if it is determined that the motor is overloaded more than a predetermined number of times, it may be determined that the motor 7 has an abnormality. When it is determined that the motor 7 has an abnormality, the washing operation may be stopped and the abnormality may be notified.

INDUSTRIAL APPLICABILITY The present disclosure is applicable to a device that rotates a rotating tub by a motor. Specifically, the present disclosure is applicable to vertical washing machines, drum washing machines, twin-tub washing machines, and the like.

REFERENCE SIGNS LIST 1 washing machine main body 2 water tub 3 drum 4 clothing entrance 5 door 6 water passage 7 motor 7a, 7b, 7c winding 8 water injection pipe 9 drainage pipe 10 operation display panel 12 blower fan 14 pulley 15 fluid balancer 16 belt 17 rotation Central axis 20 Commercial power supply 21 Rectifier 22 Choke coil 23 Smoothing capacitor 24 Inverter circuit 24a to 24f Switching element 25 Input setting unit 26 Load drive unit 27 Water supply valve 28 Drainage valve 29 Heat pump 30 Rotor position detection unit 30a, 30b, 30c Hall IC
31 control unit 32 drive circuit 33 low-pass filter processing unit 34 overload detection unit

Claims (3)

a rotating tank;
a motor that rotates the rotating tub;
an inverter circuit that converts direct current to alternating current and drives the motor;
a current detection unit that detects the current flowing through the motor;
a low-pass filter unit that performs low-pass filter processing on the current detected by the current detection unit and outputs a low-pass filtered value as a current value after processing;
an overload detection unit that detects an overload state of the motor;
a control unit that transmits a motor drive command to the inverter circuit and controls the motor through the previous inverter circuit;
with
The overload detection unit determines that the motor is in an overload state when a predetermined time elapses in a state where the processed current value output from the low-pass filter unit is equal to or greater than a first value. , canceling the overload state when the current value after the processing is a second value smaller than the first value;
The control unit controls rotation of the motor based on the determination result of the overload detection unit.
washing machine. At the time of washing in which the rotating tub is left-right reversed and the stirring operation is performed,
The control unit controls the motor so that the ON time and the OFF time are set as one cycle, and the motor is horizontally reversed for each cycle,
The time constant of the low-pass filter is set to a time substantially equal to the ON time of the motor,
The washing machine according to claim 1. The control unit reduces the rotation speed of the motor when the dewatering operation is overloaded.
The washing machine according to claim 1 or 2.

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