EP4036300A1 - Method to estimate a load behavior in a laundry treatment machine - Google Patents
Method to estimate a load behavior in a laundry treatment machine Download PDFInfo
- Publication number
- EP4036300A1 EP4036300A1 EP22164092.3A EP22164092A EP4036300A1 EP 4036300 A1 EP4036300 A1 EP 4036300A1 EP 22164092 A EP22164092 A EP 22164092A EP 4036300 A1 EP4036300 A1 EP 4036300A1
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- European Patent Office
- Prior art keywords
- load
- torque
- observer
- drive motor
- angular speed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 238000000034 method Methods 0.000 title claims abstract description 39
- 230000001133 acceleration Effects 0.000 description 25
- 238000005406 washing Methods 0.000 description 18
- 230000009466 transformation Effects 0.000 description 11
- 238000001035 drying Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 3
- 230000010355 oscillation Effects 0.000 description 3
- 238000009987 spinning Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 239000003599 detergent Substances 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000007844 bleaching agent Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
Images
Classifications
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F33/00—Control of operations performed in washing machines or washer-dryers
- D06F33/50—Control of washer-dryers characterised by the purpose or target of the control
- D06F33/76—Preventing or reducing imbalance or noise
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F34/00—Details of control systems for washing machines, washer-dryers or laundry dryers
- D06F34/14—Arrangements for detecting or measuring specific parameters
- D06F34/16—Imbalance
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F58/00—Domestic laundry dryers
- D06F58/32—Control of operations performed in domestic laundry dryers
- D06F58/34—Control of operations performed in domestic laundry dryers characterised by the purpose or target of the control
- D06F58/52—Preventing or reducing noise
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F2103/00—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers
- D06F2103/24—Spin speed; Drum movements
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F2103/00—Parameters monitored or detected for the control of domestic laundry washing machines, washer-dryers or laundry dryers
- D06F2103/44—Current or voltage
- D06F2103/46—Current or voltage of the motor driving the drum
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
- D06F2105/46—Drum speed; Actuation of motors, e.g. starting or interrupting
- D06F2105/48—Drum speed
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
- D06F2105/52—Changing sequence of operational steps; Carrying out additional operational steps; Modifying operational steps, e.g. by extending duration of steps
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
- D06F2105/00—Systems or parameters controlled or affected by the control systems of washing machines, washer-dryers or laundry dryers
- D06F2105/62—Stopping or disabling machine operation
Definitions
- the invention relates to a method to estimate a load behavior in a laundry treatment machine. Furthermore, the invention relates to a laundry treatment machine with a control unit to estimate a load behavior.
- the laundry treatment machine is a washing machine or a drying machine or a combined washing and drying machine.
- the estimation of a load inertia at the beginning of a washing cycle has a key role to set the amount of resources such as water, detergent, bleach and softener and the amount of energy in order to achieve a good washing performance without wasting resources and energy.
- the load inertia is caused by the laundry within the drum of the laundry treatment machine and varies in a wide range.
- the washing unit is suspended to the cabinet by a set of springs and dampers.
- This mechanical system is adjusted to have a resonance frequency at a relatively low angular speed between 150 rpm and 300 rpm.
- the angular speed of the drum has to cross this resonance region without interference between the tub and the cabinet. Due to an increase of the drum size and a loading capacity of the laundry treatment machine the available space between the tub and the cabinet decreased. As a consequence, a precise estimation of a load unbalance is required in order to avoid a mechanical impact between the tub and the cabinet when the resonance region is crossed.
- US 2005/204482 A1 discloses a method to estimate a load inertia and a load unbalance. The estimation is based on an angular speed signal and a torque signal during an acceleration of the drum or during superimposition of a dither signal to a substantially constant angular speed in order to excite the mechanical system of the laundry treatment machine.
- the inertia and/or the load torque is determined based on two operations of the laundry treatment machine with two different speed controller parameters and bandwidths of the speed controller.
- the speed controller regulates the angular speed of the drive motor an is part of the speed control loop.
- T em * 1 denotes the first torque signal
- ⁇ ⁇ 1 ⁇ denotes the derivative of the first angular speed signal
- T em * 2 denotes the second torque signal
- ⁇ ⁇ 2 ⁇ denotes the derivative of the second angular speed signal
- T ⁇ L denotes the load torque
- ⁇ t denotes the total inertia of the laundry treatment machine with regard to a rotation around the rotational axis.
- the inertia J m of the laundry treatment machine is known from construction data or can be measured by running a test without a distributed load inside the drum.
- the load torque can be determined, for example according to equation (1) and/or equation (2) and/or by means of a load observer as soon as the total inertia ⁇ t is estimated according to equation (3) and the load torque observer is parametrized accordingly.
- the load torque observer enables an accurate and continuous estimation of the load torque.
- the load torque observer can be easily implemented into a control unit of a laundry treatment machine. Additional hardware components, like sensors, are not required.
- the advantages of the inventive method are as follows:
- the load inertia and the total inertia can be evaluated at a constant angular speed, for example at 100 rpm, in order to avoid the use of an acceleration ramp and to avoid the risk of a mechanical impact between the tub and the cabinet.
- the method can be used to estimate the dry load at the beginning of the washing cycle without using an acceleration ramp in order to set the amount of resources and energy.
- the inertia estimation can be used to stop the drying cycle at a desired moisture retention.
- the inventive method can be used to estimate the wet load at the end of the washing cycle without using an acceleration ramp.
- the estimated load torque and an estimation of the load unbalance based thereon can be automatically adapted with the estimated total inertia.
- the inventive method can be used in a laundry treatment machine with a large drum and can be easily implemented in existing control units.
- the estimation of the inertia and/or the load torque is not affected by friction or by the speed controller setting.
- the estimation of the inertia and/or the load torque just requires an operation of the laundry treatment machine at a constant angular speed without the need of an acceleration ramp such that the inertia and/or the load torque can be estimated in an easy and quick manner.
- a method according to claim 2 ensures an easy, reliable and accurate estimation of the load behavior.
- the desired angular speed or the target speed is constant.
- the resulting speed fluctuations or speed oscillations depend on the bandwidth of the speed controller and/or on the controller parameters of the speed controller, on the mass of the load and on the total inertia.
- a change of the speed controller parameters that changes the bandwidth of the speed controller at a constant desired angular speed results in a change of the speed oscillations and of the drive torque.
- the angular speed oscillations about the constant desired angular speed could be, as example, within +- 10 rpm, or within +- 5 rpm, or within +- 2 rpm.
- a method according to claim 3 ensures an easy, reliable and accurate estimation of the load behavior.
- the mass of the load can be estimated in an easy and accurate manner depending on the load torque.
- a method according to claim 4 ensures an easy, reliable and accurate estimation of the load behavior.
- a method according to claim 5 ensures an easy, reliable and accurate estimation of the load behavior.
- the total inertia can be easily estimated according to equation (3).
- the load inertia can be easily estimated according to equation (4).
- a method according to claim 6 ensures an easy, reliable and accurate estimation of the load behavior.
- the signals are transformed into a frequency domain, in particular by computing a Fourier Transformation (FT). This transformation enables to determine respective first harmonics of the signals.
- the first harmonics are used for the subsequent determination of the inertia and/or the load torque.
- the determination of the inertia and/or the load torque is not affected by noise signals.
- the first harmonics comprise information about the frequency, the amplitude and the phase of the signals. At least one of the frequency, the amplitude and the phase are used for the subsequent estimation of the inertia and/or the load torque.
- a method according to claim 7 ensures an easy, reliable an accurate estimation of the load behavior.
- the first harmonics of the signals are calculated for example by a Fourier Transformation (FT).
- the first harmonics comprise information about the frequency, the amplitude and the phase of the signals. At least one of the frequency, the amplitude and the phase are used for the subsequent estimation of the inertia and/or the load torque.
- a method according to claim 8 ensures an easy, reliable and accurate estimation of the load behavior.
- the angular position and/or the drive torque of the drive motor can either be measured or estimated.
- the angular position is used to calculate an observer error.
- a method according to claim 9 ensures an easy, reliable and accurate estimation of the load behavior.
- the observer error is used to estimate and/or correct internal states of the load torque observer.
- the internal states of the load torque observer are in particular the observed angular position, an observed angular acceleration and the load torque.
- the observer error is multiplied with observer coefficients or observer gains. The observer coefficients are used to adapt the accuracy and the behavior of the load torque observer.
- a method according to claim 10 ensures an easy, reliable and accurate estimation of the load behavior.
- the observer error is multiplied with observer coefficients or observer gains in order to calculate observer signals. These observer signals are used to estimate and/or correct the internal states of the observer.
- a first observer signal is calculated by multiplying a derivative of the observer error with a first observer coefficient.
- a second observer signal is calculated by multiplying the observer error with a second observer coefficient.
- a third observer signal is calculated by multiplying the observer error with a third observer coefficient and by integrating the resulting signal.
- the load torque depends on the sum of the first observer signal, the second observer signal and the third observer signal.
- a method according to claim 11 ensures an easy, reliable and accurate estimation of the load behavior.
- An observed angular acceleration and in consequence the observed angular position depends on the total inertia of the laundry treatment machine and the load.
- the total inertia is estimated according to equation (3).
- the total inertia can be adapted during the operation of the laundry treatment machine, if necessary. For example, the total inertia increases depending on the wetness of the laundry.
- a method according to claim 12 ensures an easy, reliable and accurate estimation of the load behavior.
- Sensorless drive motors are well known and do not comprise an angular position sensor and an angular speed sensor.
- the angular position of the drive motor is estimated, for example by means of a position and/or speed estimator or a position and/or speed observer.
- the load torque observer is preferably provided with an estimated angular position of the drive motor.
- a method according to claim 13 ensures an easy, reliable and accurate estimation of the load behavior.
- the load torque observer is provided with the desired drive torque of the drive motor.
- An output signal of the speed controller is used to estimate the drive torque.
- This output signal characterizes the desired electromagnetic drive torque of the drive motor and can be used to estimate the drive torque and/or the load torque which acts on the drum.
- Fig. 1 shows a laundry treatment machine, namely a washing machine 1 with a cabinet 2 and a washing unit 3.
- the washing unit 3 comprises a tub 4 and a drum 5.
- the tub 4 is mounted to the cabinet 2 via dampers 6 and springs 7.
- the drum 5 is mounted in a rotatable manner to the tub 4.
- the drum 5 is connected via a drive shaft 8 with a drive motor 9.
- the drive motor 9 is mounted at a backside of the tub 4.
- the drive motor 9 rotates the drum 5 around a horizontal rotational axis 10.
- the washing machine 1 comprises several lifters 11 to move the laundry.
- the lifters 11 are mounted in equal angular distances to an inner side of the drum 5.
- the washing machine 1 comprises a control unit 12 to control the operation of the washing machine 1.
- the drive motor 9 has an angular position ⁇ , an angular speed ⁇ and an angular acceleration ⁇ . Due to the stiff drive shaft 8 the angular position, the angular speed and the angular acceleration of the drum 5 corresponds to the angular position ⁇ , the angular speed ⁇ and the angular acceleration ⁇ . In case of belt driven motor, the pulley ratio will be used to evaluate the angular position, the angular speed and the angular acceleration of the drum starting from the angular position, the angular speed and the angular acceleration of the motor.
- the load L namely the laundry inside the drum 5 produces a load torque T L .
- T L ⁇ mgr sin ⁇ + ⁇
- m denotes the real mass of the load L
- g denotes the gravitational acceleration
- r denotes the drum radius
- ⁇ denotes the angular relative position of the load L inside the drum, namely an angle between the position of the load L and a drum reference position.
- the angular positions ⁇ and ⁇ and the mass m are unknown.
- the gravitational acceleration g and the drum radius r are known.
- the drive motor 9 creates a drive torque T em which accelerates the drum 5.
- the drive torque T em is superimposed by the load torque T L .
- the control unit 12 comprises a speed controller 13, a torque controller 14, a first coordinate transformation 15, a pulse width modulator 16, a position and speed observer 17, a second coordinate transformation 18 and a load torque observer 19.
- the torque controller 14 is part of an inner control loop or a torque control loop to control the drive torque T em of the drive motor 9.
- the torque controller 14 is a PI controller.
- the torque controller 14 is provided with a desired drive torque T em * and the drive motor currents which are denoted in common with i abc .
- the drive motor currents i abc are transformed by means of the second coordinate transformation 18 into a dq coordinate system.
- the corresponding currents are denoted in common with i dq .
- the torque controller 14 creates in the dq coordinate system desired voltages which are denoted in common with v * dq .
- the voltages v * dq are transformed by means of the first coordinate transformation 15 into desired voltages in an abc coordinate system which are denoted in common with v abc .
- the voltages v abc are provided to the pulse width modulator 16 which creates via a switch circuit currents i a , i b , i c to operate the drive motor 9 with a torque T em which corresponds to the desired torque T em * .
- the drive motor 9 is designed sensorless, namely without a speed sensor and a torque sensor. Therefore, the position and speed observer 17 is used to produce an estimated angular position ⁇ and an estimated angular speed ⁇ .
- the position and speed observer 17 is provided with the voltages v abc and the currents i abc .
- the estimated angular position ⁇ is provided to the first coordinate transformation 15 and the second coordinate transformation 18.
- the speed controller 13 is part of an outer control loop or a speed control loop.
- the speed controller 13 is provided with the difference of a desired angular speed ⁇ ⁇ and the estimated angular speed ⁇ .
- the output signal of the speed controller 13 is the desired drive torque T em * .
- the load torque observer 19 evaluates an estimated load torque T ⁇ L .
- the load torque observer 19 is provided with the desired drive torque T em * and the estimated angular position ⁇ as input signals.
- the load torque observer 19 calculates an observer error e obs which is the difference of the estimated angular position ⁇ and an observed angular position ⁇ obs .
- the observer coefficients are for example set to
- the load torque observer 19 calculates an observed angular speed ⁇ obs by integrating the observed angular acceleration ⁇ obs . Furthermore, the load torque observer 19 calculates the observed angular position ⁇ obs by integrating the observed angular speed ⁇ obs .
- step S 1 the speed controller 13 is parametrized with first controller parameters P 1 .
- the speed controller 13 is a PI controller.
- a second step S 2 the drum 5 is accelerated by means of the drive motor 9 as example from 0 rpm to 100 rpm.
- a third step S 3 the drum 5 is rotated with an essentially constant drum speed ⁇ .
- the control unit 12 transforms the desired drive torque T em * and the estimated angular speed ⁇ into the frequency domain by calculating a Fourier Transformation.
- the first harmonic of the desired drive torque T em * is stored in the control unit 12 and is denoted T em * 1 .
- the first harmonic information for example the frequency, the amplitude and the phase, of the estimated angular speed ⁇ are used to get an estimated angular acceleration which is denoted ⁇ ⁇ 1 ⁇ .
- the estimated angular acceleration ⁇ ⁇ 1 ⁇ is stored in the control unit 12.
- step S 4 the speed controller 13 is parametrized with second controller parameters P 2 .
- a fifth step S 5 the drum 5 is rotated with an essentially constant drum speed ⁇ .
- the control unit 12 transforms the desired drive torque T em * and the estimated angular speed ⁇ into the frequency domain by calculating a Fourier Transformation.
- the first harmonic of the desired drive torque T em * is stored in the control unit 12 and is denoted T em * 2 .
- the first harmonic information for example the frequency, the amplitude and the phase, of the estimated angular speed ⁇ are used to get an estimated angular acceleration which is denoted ⁇ ⁇ 2 ⁇ .
- the estimated angular acceleration ⁇ ⁇ 2 ⁇ is stored in the control unit 12.
- Equation (15) is illustrated in fig. 7 .
- Fig. 8 illustrates the estimated load torque T ⁇ L .
- the load inertia ⁇ L , the load torque T ⁇ L , the mass m ⁇ and the angular load position ⁇ characterize the behavior of the load L and can be used for several purposes, for example to adapt the maximum spinning speed, to compensate the load L by filling the balancers 11 with water, to estimate the dry load at the beginning of the washing cycle and to set properly the required amount of water and/or detergent, to estimate the wet load at the beginning of the spinning cycle and to estimate the remaining moisture retention during a drying process.
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- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Control Of Washing Machine And Dryer (AREA)
Abstract
Description
- The invention relates to a method to estimate a load behavior in a laundry treatment machine. Furthermore, the invention relates to a laundry treatment machine with a control unit to estimate a load behavior. For example, the laundry treatment machine is a washing machine or a drying machine or a combined washing and drying machine.
- The estimation of a load inertia at the beginning of a washing cycle has a key role to set the amount of resources such as water, detergent, bleach and softener and the amount of energy in order to achieve a good washing performance without wasting resources and energy. The load inertia is caused by the laundry within the drum of the laundry treatment machine and varies in a wide range.
- The washing unit is suspended to the cabinet by a set of springs and dampers. This mechanical system is adjusted to have a resonance frequency at a relatively low angular speed between 150 rpm and 300 rpm. During the spinning phase, the angular speed of the drum has to cross this resonance region without interference between the tub and the cabinet. Due to an increase of the drum size and a loading capacity of the laundry treatment machine the available space between the tub and the cabinet decreased. As a consequence, a precise estimation of a load unbalance is required in order to avoid a mechanical impact between the tub and the cabinet when the resonance region is crossed.
-
US 2005/204482 A1 discloses a method to estimate a load inertia and a load unbalance. The estimation is based on an angular speed signal and a torque signal during an acceleration of the drum or during superimposition of a dither signal to a substantially constant angular speed in order to excite the mechanical system of the laundry treatment machine. - It is an object of the present invention to provide a method to estimate a load behavior in a laundry treatment machine in an easy, reliable and accurate manner.
- This object is achieved by a method comprising the steps of
claim 1. According to the inventive method the inertia and/or the load torque is determined based on two operations of the laundry treatment machine with two different speed controller parameters and bandwidths of the speed controller. The speed controller regulates the angular speed of the drive motor an is part of the speed control loop. The first operation can be described by
T̂L denotes the load torque and
Ĵt denotes the total inertia of the laundry treatment machine with regard to a rotation around the rotational axis. -
-
- ĴL
- denotes the load inertia and
- Jm
- denotes the inertia of the laundry treatment machine.
- The inertia Jm of the laundry treatment machine is known from construction data or can be measured by running a test without a distributed load inside the drum.
- Furthermore, in case that the load inertia is evaluated according to equation (4), the load torque can be determined, for example according to equation (1) and/or equation (2) and/or by means of a load observer as soon as the total inertia Ĵt is estimated according to equation (3) and the load torque observer is parametrized accordingly.
- The load torque observer enables an accurate and continuous estimation of the load torque. The load torque observer can be easily implemented into a control unit of a laundry treatment machine. Additional hardware components, like sensors, are not required.
- The advantages of the inventive method are as follows:
The load inertia and the total inertia can be evaluated at a constant angular speed, for example at 100 rpm, in order to avoid the use of an acceleration ramp and to avoid the risk of a mechanical impact between the tub and the cabinet. The same applies for the estimation of a load unbalance based on the load torque. The method can be used to estimate the dry load at the beginning of the washing cycle without using an acceleration ramp in order to set the amount of resources and energy. In case of a combined washing and drying machine or a drying machine the inertia estimation can be used to stop the drying cycle at a desired moisture retention. Furthermore, the inventive method can be used to estimate the wet load at the end of the washing cycle without using an acceleration ramp. The estimated load torque and an estimation of the load unbalance based thereon can be automatically adapted with the estimated total inertia. The inventive method can be used in a laundry treatment machine with a large drum and can be easily implemented in existing control units. The estimation of the inertia and/or the load torque is not affected by friction or by the speed controller setting. Furthermore, the estimation of the inertia and/or the load torque just requires an operation of the laundry treatment machine at a constant angular speed without the need of an acceleration ramp such that the inertia and/or the load torque can be estimated in an easy and quick manner. - A method according to
claim 2 ensures an easy, reliable and accurate estimation of the load behavior. The desired angular speed or the target speed is constant. The resulting speed fluctuations or speed oscillations depend on the bandwidth of the speed controller and/or on the controller parameters of the speed controller, on the mass of the load and on the total inertia. A change of the speed controller parameters that changes the bandwidth of the speed controller at a constant desired angular speed results in a change of the speed oscillations and of the drive torque. The angular speed oscillations about the constant desired angular speed could be, as example, within +- 10 rpm, or within +- 5 rpm, or within +- 2 rpm. -
- m̂
- denotes the mass of the load which corresponds to the unbalance mass,
- max(T̂L)
- denotes the maximum of the load torque,
- g
- denotes the gravitational acceleration and
- r
- denotes the drum radius.
-
- Θ̂
- denotes the angular drum position in relation to a reference position,
- σ̂
- denotes the angular relative load position inside the drum,
- T̂L
- denotes the load torque,
- m̂
- denotes the mass of the load which corresponds to the unbalance mass,
- g
- denotes the gravitational acceleration and
- r
- denotes the drum radius.
-
- α̂ denotes the angular position of the load in relation to the reference position
- such that
- A method according to
claim 5 ensures an easy, reliable and accurate estimation of the load behavior. The total inertia can be easily estimated according to equation (3). Furthermore, the load inertia can be easily estimated according to equation (4). - A method according to
claim 6 ensures an easy, reliable and accurate estimation of the load behavior. The signals are transformed into a frequency domain, in particular by computing a Fourier Transformation (FT). This transformation enables to determine respective first harmonics of the signals. The first harmonics are used for the subsequent determination of the inertia and/or the load torque. The determination of the inertia and/or the load torque is not affected by noise signals. The first harmonics comprise information about the frequency, the amplitude and the phase of the signals. At least one of the frequency, the amplitude and the phase are used for the subsequent estimation of the inertia and/or the load torque. - A method according to
claim 7 ensures an easy, reliable an accurate estimation of the load behavior. By using the first harmonics of the signals the estimation of the inertia and/or the load torque is not affected by noise signals. The first harmonics of the signals are calculated for example by a Fourier Transformation (FT). The first harmonics comprise information about the frequency, the amplitude and the phase of the signals. At least one of the frequency, the amplitude and the phase are used for the subsequent estimation of the inertia and/or the load torque. - A method according to
claim 8 ensures an easy, reliable and accurate estimation of the load behavior. The angular position and/or the drive torque of the drive motor can either be measured or estimated. The angular position is used to calculate an observer error. - A method according to claim 9 ensures an easy, reliable and accurate estimation of the load behavior. The observer error is used to estimate and/or correct internal states of the load torque observer. The internal states of the load torque observer are in particular the observed angular position, an observed angular acceleration and the load torque. The observer error is multiplied with observer coefficients or observer gains. The observer coefficients are used to adapt the accuracy and the behavior of the load torque observer.
- A method according to
claim 10 ensures an easy, reliable and accurate estimation of the load behavior. The observer error is multiplied with observer coefficients or observer gains in order to calculate observer signals. These observer signals are used to estimate and/or correct the internal states of the observer. A first observer signal is calculated by multiplying a derivative of the observer error with a first observer coefficient. A second observer signal is calculated by multiplying the observer error with a second observer coefficient. Furthermore, a third observer signal is calculated by multiplying the observer error with a third observer coefficient and by integrating the resulting signal. The load torque depends on the sum of the first observer signal, the second observer signal and the third observer signal. - A method according to
claim 11 ensures an easy, reliable and accurate estimation of the load behavior. An observed angular acceleration and in consequence the observed angular position depends on the total inertia of the laundry treatment machine and the load. The total inertia is estimated according to equation (3). The total inertia can be adapted during the operation of the laundry treatment machine, if necessary. For example, the total inertia increases depending on the wetness of the laundry. - A method according to
claim 12 ensures an easy, reliable and accurate estimation of the load behavior. Sensorless drive motors are well known and do not comprise an angular position sensor and an angular speed sensor. Hence, the angular position of the drive motor is estimated, for example by means of a position and/or speed estimator or a position and/or speed observer. The load torque observer is preferably provided with an estimated angular position of the drive motor. - A method according to
claim 13 ensures an easy, reliable and accurate estimation of the load behavior. The load torque observer is provided with the desired drive torque of the drive motor. An output signal of the speed controller is used to estimate the drive torque. This output signal characterizes the desired electromagnetic drive torque of the drive motor and can be used to estimate the drive torque and/or the load torque which acts on the drum. - Furthermore, it is an object of the present invention to provide a laundry treatment machine which enables to estimate a load behavior in an easy, reliable and accurate manner.
- This object is achieved by a laundry treatment machine with the features of
claim 14. The advantages of the laundry treatment machine according to the invention correspond to the advantages already described in connection with the method according to the invention. - Further features, advantages and details of the invention will be apparent from the following description of an embodiment which refers to the accompanying drawings.
- Fig. 1
- shows a schematic view of a laundry treatment machine with a drum, a drive motor and a control unit,
- Fig. 2
- shows a schematic cross sectional view of the drum with a load located inside the drum,
- Fig. 3
- shows a block diagram of a controller and a load torque observer implemented in the control unit,
- Fig. 4
- shows a block diagram of the load torque observer in
Fig. 3 , - Fig. 5
- shows a flow chart of a method to estimate a total inertia of the laundry treatment machine and the load with respect to a rotation of the drum around a rotational axis,
- Fig. 6
- shows a time diagram of an angular speed and a drive torque of the drive motor during a first operation and a second operation of the laundry treatment machine in order to estimate the total inertia according to the flow chart in
Fig. 5 , - Fig. 7
- shows a first torque signal and a first angular acceleration signal during a first operation and a second torque signal and a second angular acceleration signal during a second operation of the laundry treatment machine as well as a torque difference signal and an acceleration difference signal depending on the angular position of the drum in order to estimate the total inertia, and
- Fig. 8
- shows an estimated load torque depending on an angular position of the drum.
-
Fig. 1 shows a laundry treatment machine, namely awashing machine 1 with acabinet 2 and awashing unit 3. Thewashing unit 3 comprises atub 4 and adrum 5. Thetub 4 is mounted to thecabinet 2 viadampers 6 and springs 7. - The
drum 5 is mounted in a rotatable manner to thetub 4. Thedrum 5 is connected via adrive shaft 8 with a drive motor 9. The drive motor 9 is mounted at a backside of thetub 4. The drive motor 9 rotates thedrum 5 around a horizontalrotational axis 10. - The
washing machine 1 comprisesseveral lifters 11 to move the laundry. Thelifters 11 are mounted in equal angular distances to an inner side of thedrum 5. - Furthermore, the
washing machine 1 comprises acontrol unit 12 to control the operation of thewashing machine 1. The drive motor 9 has an angular position Θ, an angular speed ω and an angular acceleration ω̇. Due to thestiff drive shaft 8 the angular position, the angular speed and the angular acceleration of thedrum 5 corresponds to the angular position Θ, the angular speed ω and the angular acceleration ω̇. In case of belt driven motor, the pulley ratio will be used to evaluate the angular position, the angular speed and the angular acceleration of the drum starting from the angular position, the angular speed and the angular acceleration of the motor. - The load L, namely the laundry inside the
drum 5 produces a load torque TL. In case that the angular speed of thedrum 5 is higher than a satelization speed the load torque TL can be described by
m denotes the real mass of the load L,
g denotes the gravitational acceleration,
r denotes the drum radius,
denotes the angular position of the drum in relation to a reference position Θ0, and
σ denotes the angular relative position of the load L inside the drum, namely an angle between the position of the load L and a drum reference position. -
- α
- denotes the angular position of the load L in relation to the reference position θ0.
-
- The drive motor 9 creates a drive torque Tem which accelerates the
drum 5. The drive torque Tem is superimposed by the load torque TL. - The
control unit 12 comprises aspeed controller 13, atorque controller 14, a first coordinatetransformation 15, apulse width modulator 16, a position andspeed observer 17, a second coordinatetransformation 18 and aload torque observer 19. - The
torque controller 14 is part of an inner control loop or a torque control loop to control the drive torque Tem of the drive motor 9. For example, thetorque controller 14 is a PI controller. Thetorque controller 14 is provided with a desired drive torquetransformation 18 into a dq coordinate system. The corresponding currents are denoted in common with idq. Thetorque controller 14 creates in the dq coordinate system desired voltages which are denoted in common with v* dq. The voltages v* dq are transformed by means of the first coordinatetransformation 15 into desired voltages in an abc coordinate system which are denoted in common with vabc. The voltages vabc are provided to thepulse width modulator 16 which creates via a switch circuit currents ia, ib, ic to operate the drive motor 9 with a torque Tem which corresponds to the desired torque - The drive motor 9 is designed sensorless, namely without a speed sensor and a torque sensor. Therefore, the position and
speed observer 17 is used to produce an estimated angular position Θ̂ and an estimated angular speed ω̂. The position andspeed observer 17 is provided with the voltages vabc and the currents iabc. The estimated angular position Θ̂ is provided to the first coordinatetransformation 15 and the second coordinatetransformation 18. -
- The
load torque observer 19 evaluates an estimated load torque T̂L. Theload torque observer 19 is provided with the desired drive torqueload torque observer 19 calculates an observer error eobs which is the difference of the estimated angular position Θ̂ and an observed angular position Θobs. -
- k1 denotes a first observer coefficient,
- k2 denotes a second observer coefficient,
- k3 denotes a third observer coefficient,
- s denotes a derivator, and
- 1/s denotes an integrator.
- The observer coefficients are for example set to
- K1 = 64,
- K2 = 13, and
- K3=5.
-
-
- Ĵt is the total inertia of those parts of the
washing machine 1 which rotate around therotational axis 10, in particular of thedrum 5 with thebalancers 11, of thedrive shaft 8, of the drive motor 9, and of the load L. The total inertia can be described by - ĴL denotes the load inertia and Jm denotes the inertia of the
washing machine 1. The inertia of thewashing machine 1 is known from construction data. - The
load torque observer 19 calculates an observed angular speed ω obs by integrating the observed angular acceleration ω̇ obs . Furthermore, theload torque observer 19 calculates the observed angular position Θobs by integrating the observed angular speed ωobs . - In the following the estimation of the total inertia Ĵt is described in detail:
In step S1 thespeed controller 13 is parametrized with first controller parameters P1. For example, thespeed controller 13 is a PI controller. - In a second step S2 the
drum 5 is accelerated by means of the drive motor 9 as example from 0 rpm to 100 rpm. - Afterwards, in a third step S3 the
drum 5 is rotated with an essentially constant drum speed ω. During the third step S3 thecontrol unit 12 transforms the desired drive torquecontrol unit 12 and is denotedcontrol unit 12. - Afterwards, in a step S4 the
speed controller 13 is parametrized with second controller parameters P2. - Afterwards, in a fifth step S5 the
drum 5 is rotated with an essentially constant drum speed ω. During the step S5 thecontrol unit 12 transforms the desired drive torquecontrol unit 12 and is denotedcontrol unit 12. -
- The estimated total inertia Ĵt is used to parametrize the
load torque observer 19. Equation (15) is illustrated infig. 7 . -
- The angular position Θ̂ of the load L is already known.
Fig. 8 illustrates the estimated load torque T̂L. - The load inertia ĴL, the load torque T̂L, the mass m̂ and the angular load position Θ̂ characterize the behavior of the load L and can be used for several purposes, for example to adapt the maximum spinning speed, to compensate the load L by filling the
balancers 11 with water, to estimate the dry load at the beginning of the washing cycle and to set properly the required amount of water and/or detergent, to estimate the wet load at the beginning of the spinning cycle and to estimate the remaining moisture retention during a drying process.
Claims (14)
- Method to estimate a load behavior in a laundry treatment machine with the steps of:- providing a laundry treatment machine (1) with a drum (5), a drive motor (9) to rotate the drum (5) around a rotational axis (10) and a controller (13) to regulate an angular speed of the drive motor (9),- performing a first operation of the laundry treatment machine (1) with a load (L) inside the drum (5), wherein the controller (13) is operated with first controller parameters (Pi),- determining a first torque signal- performing a second operation of the laundry treatment machine (1) with the load (L) inside the drum (5), wherein the controller (13) is operated with second controller parameters (P2),- determining a second torque signal- determining an inertia (Ĵt, ĴL ) and/or a load torque (T̂L ) caused by the load (L) depending on the first torque signal
- Method according to claim 1, characterized in
that at least one of the first operation and the second operation is performed at a constant desired target angular speed (ω∗), while in particular a real speed (ω) oscillates according to the controller parameters (P1, P2) and the load (L). - Method according to claim 1 or 2, characterized
by the step of determining a mass (m̂) of the load (L) depending on the load torque (T̂L ). - Method according to at least one of the preceding claims, characterized
by the step of determining an angular load position (â) of the load (L) depending on the load torque (T̂L ). - Method according to at least one of the preceding claims, characterized
by the step of determining a total inertia (Ĵt ) of the laundry treatment machine (1) and the load (L), wherein in particular a load inertia (ĴL ) is the difference between the total inertia (Ĵt) and a machine inertia (Ĵm). - Method according to at least one of the preceding claims, characterized in
that a respective first harmonic of the first torque signal - Method according to at least one of the preceding claims, characterized in
that the load torque observer (19) determines an observer error (eobs ) depending on an angular position (Θ̂) of the drive motor (9) and an observed angular position (Θobs ). - Method according to at least one of the preceding claims, characterized in
that the load torque observer (19) determines observer signals (ki, k2, k3) depending on an observer error (eobs ) and observer coefficients (K1, K2, K3) to determine the load torque (T̂L ) and/or an observed angular position (Θobs ). - Method according to at least one of the preceding claims, characterized in
that the load torque observer (19) determines an observed angular position (Θobs ) depending on a total inertia (Ĵt ) of the laundry treatment machine (1) and the load (L). - Method according to at least one of claims 8 to 11, characterized in that the drive motor (9) is designed sensorless and the angular position (Θ̂) of the drive motor (9) is estimated, in particular by means of a position observer (17).
- Laundry treatment machine with- a drum (5),- a drive motor (9) to rotate the drum (5) around a rotational axis (10), and- a control unit (12) to estimate a load behavior with a controller (13) to regulate an angular speed of the drive motor (9), wherein the control unit (12) is designed such that-- a first operation of the laundry treatment machine (1) with a load (L) inside the drum (5) is performed, wherein the controller (13) is operated with first controller parameters (Pi),-- a first torque signal-- a second operation of the laundry treatment machine (1) with the load (L) inside the drum (5) is performed, wherein the controller (13) is operated with second controller parameters (P2),-- a second torque signal-- an inertia (Ĵt , ĴL ) and/or a load torque (T̂L ) caused by the load (L) is determined depending on the first torque signal
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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EP22164092.3A EP4036300A1 (en) | 2020-03-02 | 2020-03-02 | Method to estimate a load behavior in a laundry treatment machine |
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Application Number | Priority Date | Filing Date | Title |
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EP20160332.1A EP3875661B1 (en) | 2020-03-02 | 2020-03-02 | Method to estimate a load behavior in a laundry treatment machine |
EP22164092.3A EP4036300A1 (en) | 2020-03-02 | 2020-03-02 | Method to estimate a load behavior in a laundry treatment machine |
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EP20160332.1A Division EP3875661B1 (en) | 2020-03-02 | 2020-03-02 | Method to estimate a load behavior in a laundry treatment machine |
EP20160332.1A Division-Into EP3875661B1 (en) | 2020-03-02 | 2020-03-02 | Method to estimate a load behavior in a laundry treatment machine |
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EP4036300A1 true EP4036300A1 (en) | 2022-08-03 |
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EP22164092.3A Pending EP4036300A1 (en) | 2020-03-02 | 2020-03-02 | Method to estimate a load behavior in a laundry treatment machine |
EP20160332.1A Active EP3875661B1 (en) | 2020-03-02 | 2020-03-02 | Method to estimate a load behavior in a laundry treatment machine |
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EP (2) | EP4036300A1 (en) |
ES (1) | ES2920484T3 (en) |
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050204482A1 (en) | 2003-04-28 | 2005-09-22 | Emerson Electric Co. | Method and system for operating a clothes washing machine |
DE102008055091A1 (en) * | 2008-12-22 | 2010-06-24 | BSH Bosch und Siemens Hausgeräte GmbH | Method for controlling a laundry distribution operation of a household appliance for the care of laundry |
EP2607535A2 (en) * | 2011-12-20 | 2013-06-26 | Whirlpool Corporation | Method of operating a laundry treating appliance and appliance implementing it |
US20190112745A1 (en) * | 2017-10-17 | 2019-04-18 | Fisher & Paykel Appliances Limited | Laundry appliance and operating method |
-
2020
- 2020-03-02 EP EP22164092.3A patent/EP4036300A1/en active Pending
- 2020-03-02 ES ES20160332T patent/ES2920484T3/en active Active
- 2020-03-02 EP EP20160332.1A patent/EP3875661B1/en active Active
- 2020-03-02 PL PL20160332.1T patent/PL3875661T3/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050204482A1 (en) | 2003-04-28 | 2005-09-22 | Emerson Electric Co. | Method and system for operating a clothes washing machine |
DE102008055091A1 (en) * | 2008-12-22 | 2010-06-24 | BSH Bosch und Siemens Hausgeräte GmbH | Method for controlling a laundry distribution operation of a household appliance for the care of laundry |
EP2607535A2 (en) * | 2011-12-20 | 2013-06-26 | Whirlpool Corporation | Method of operating a laundry treating appliance and appliance implementing it |
US20190112745A1 (en) * | 2017-10-17 | 2019-04-18 | Fisher & Paykel Appliances Limited | Laundry appliance and operating method |
Also Published As
Publication number | Publication date |
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EP3875661A1 (en) | 2021-09-08 |
ES2920484T3 (en) | 2022-08-04 |
EP3875661B1 (en) | 2022-04-27 |
PL3875661T3 (en) | 2022-08-16 |
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