Noise cancellation for household appliances

Abstract

A motor control method for a home appliance for reducing noise during use of a home appliance including a washing machine and a kitchen machine. The method obtains a cancellation signal configured to reduce noise of the home appliance, and combines the cancellation signal with a motor control signal configured to control a speed of the motor to form a combined signal, and then applies the combined signal to the motor. Signal parameters of the cancellation signal, including any one or more of frequency, phase, and amplitude, are selected for noise cancellation.

Description

Technical Field

[0001] The present invention relates to motor control of household appliances, and more particularly, but not exclusively, to reducing noise and / or vibration in household appliances. In particular, the motor control system of the present invention is applicable to washing machines, including clothes cleaners and dryers. Background Art

[0002] A household appliance or home appliance typically has at least one motor that is configured to rotate a load such as a fan, drum, or spray arm. These may be referred to as motor-driven appliances, and also include range hoods, dishwashers, vacuum cleaners, and air conditioning units. The motor, which is the central operating component or excitation of a household appliance, is typically the cause of noise or vibration generated by the appliance. Noise that is at least above a desired level is undesirable in a household appliance because it causes distraction or damage to the user's home. Therefore, it is advantageous to reduce or improve noise, if possible. In some cases, noise is generated by the normal operation of the appliance, and at least a portion of the noise is unavoidable.

[0003] Torque ripple (periodic disturbances in torque) is a source of unwanted noise. One component of torque ripple is the cogging torque caused by field variations between the permanent magnets and the iron teeth on the rotor and stator. Other torque ripple components may also be present when current is applied to the stator. Reduction of cogging torque and torque ripple can be achieved through motor design, including careful analysis of the motor geometry. However, even changing the motor design after it has been designed can introduce more problems.

[0004] Motors and motor control electronics have both electronic and mechanical components. The motor may be designed and produced to focus on the mechanical features, and a separate motor controller may be added as an electronic component, such as on a printed circuit board (PCB). Typically, the mechanical motor or magnetic designer is interested in improving cogging and torque ripple, which is usually achieved by optimizing the motor geometry. The design of the motor controller focuses on driving the motor accurately, assuming that the mechanical motor design (including noise and vibration reduction) has been completed.

[0005] The above-mentioned household appliances, although performing satisfactorily, can be improved by reducing the amount of noise and / or vibration they generate. It is therefore an object of the present invention to provide a method and system for reducing or improving the noise generated by household appliances which will at least to some extent overcome the above-mentioned disadvantages, or which will at least provide the public with a useful choice. Summary of the invention

[0006] According to one aspect, the present invention can be broadly described as a method for reducing noise of a household appliance, the household appliance including a motor, the method comprising the steps of obtaining a motor control signal configured to control the speed of the motor, obtaining an elimination signal configured to reduce the noise of the household appliance, combining the motor control signal and the elimination signal to form a combined signal, and applying the combined signal to the motor.

[0007] Optionally, the step of obtaining a cancellation signal comprises the following steps:

[0008] identifying one or more frequencies of the household appliance; and

[0009] A cancellation signal is calculated based on the one or more frequencies.

[0010] Optionally, the step of identifying one or more frequencies comprises the step of identifying one or more frequencies, or load rotational speed, at each of the one or more motors.

[0011] Optionally, the cancellation signal is configured to reduce motor excitation at the identified one or more frequencies.

[0012] Optionally, the step of calculating the cancellation signal comprises the following steps:

[0013] Harmonics of the electrical frequency associated with each of the identified frequencies are calculated or selected.

[0014] Optionally, the step of identifying the one or more frequencies comprises:

[0015] The noise level of the household appliance is monitored for a plurality of motor speeds.

[0016] Optionally, the step of identifying one or more resonant frequencies comprises any one or more of the following steps:

[0017] driving the motor at a plurality of motor drive frequencies or speeds;

[0018] Measuring noise of the appliance at each of the plurality of frequencies or speeds; and identifying frequencies where noise levels are high relative to adjacent frequencies.

[0019] The plurality of motor drive speeds may be a range of speeds, or may be a selected set of speeds, or spaced apart speeds.

[0020] Optionally, at least one or each of the one or more frequencies is a resonant frequency.

[0021] Optionally, the cancellation signal comprises a sinusoidal signal or a plurality of component sinusoidal signals.

[0022] Optionally, the step of obtaining the cancellation signal comprises any one or more of the following steps: obtaining the phase of the cancellation signal,

[0023] Get the amplitude of the cancellation signal,

[0024] The frequency of the cancellation signal is obtained.

[0025] Optionally, the step of obtaining the cancellation signal includes:

[0026] obtaining the phase, amplitude and / or frequency of multiple component signals, and

[0027] The plurality of component signals are combined to obtain the cancellation signal.

[0028] Forming the cancellation signal from a plurality of component signals allows cancellation of a plurality of noise excitations, or allows improved noise reduction.Where a cancellation signal is described, it may be interpreted as a combination of the component signals.

[0029] Optionally, the amplitude of the cancellation signal is 2% to 5% of the amplitude of the motor control signal. Optionally, the amplitude of the cancellation signal is less than 10% of the amplitude of the motor control signal. Optionally, less than 7%, optionally less than 5%.

[0030] Optionally, the step of obtaining the phase of the cancellation signal comprises any one or more of the following steps: loading a stored phase for the cancellation signal,

[0031] testing one or more potential phases and selecting a phase from the tested phases,

[0032] testing one or a series of potential phases and selecting a phase from the tested series of potential phases, testing a series of phases and using an optimization function to select the best phase,

[0033] adjusting the phase based on feedback from the home appliance, and / or

[0034] The phase is adjusted based on sensor measurements from the home appliance.

[0035] These steps can be performed independently of each other and can independently obtain the phase. However, it is also possible to use a combination of them to generate the phase, which can be more precise or provide options.

[0036] Optionally, the step of obtaining the phase and / or amplitude of the cancellation signal comprises the following steps:

[0037] One or more sensor measurements are used to adjust the phase and / or amplitude.

[0038] Optionally, the sensor measurement adjusts only the phase.

[0039] Optionally, each of the one or more sensor measurements is any one or more of an audio measurement, a noise measurement, an electrical measurement and / or a vibration measurement.

[0040] Optionally, each of the one or more sensor measurements is associated with any one or more of: the motor, the load, or the external environment. Optionally, multiple sensor measurements are used, with one or more sensors on the motor, the load, and / or the external environment. Optionally, only one of the motor, the load, or the external environment has a sensor.

[0041] Optionally, the step of obtaining a cancellation signal comprises the following steps:

[0042] calibrate the signal removal function, and

[0043] A cancellation signal is generated based on the cancellation signal function.

[0044] Optionally, the step of calibrating the signal elimination function comprises the following steps:

[0045] Obtain the noise data of the household appliance, and

[0046] Signal parameters for the cancellation signal are obtained at one or more frequencies.

[0047] Noise data refers to any suitable measure of noise, such as total noise amplitude or frequency response of noise. Optionally, the signal parameters include any one or more of phase, amplitude or frequency.

[0048] Optionally, the signal parameters of amplitude and / or frequency are preconfigured, and the signal parameter of phase is configurable.

[0049] Optionally, the step of recalibrating the cancellation signal function is included.

[0050] Optionally, the step of obtaining noise data comprises the step of sensing noise generated by the household appliance at a plurality of frequencies.

[0051] Optionally, the sensing is performed by a sensor, such as an audio sensor or a vibration sensor.

[0052] Optionally, the step of obtaining the cancellation signal includes:

[0053] Get feedback signals, and

[0054] The cancellation signal is generated based on the feedback signal.

[0055] Optionally, the feedback signal represents any one or more of the following:

[0056] The operating parameters of the machine;

[0057] the noise and / or vibration of components of the household appliance; and

[0058] The noise and / or vibration of the household appliance.

[0059] Optionally, the feedback signal represents any one or more of the following: an electrical signal; an audio signal; a vibration signal; an error signal.

[0060] Optionally, the step of obtaining the cancellation signal includes:

[0061] Noise generated by a household appliance driven by a motor is identified, and a cancellation signal of the excitation configured to reduce a frequency of the motor generating the noise is calculated.

[0062] Optionally, the step of calculating the cancellation signal comprises any one or more of the following:

[0063] Lookup table,

[0064] A lookup table that links the undesired noise parameters to the cancellation signal parameters,

[0065] Link the motor parameters to a lookup table of cancellation signal parameters,

[0066] Minimize the feedback signal,

[0067] Minimize audible feedback, and / or

[0068] Minimize vibration feedback signals.

[0069] The lookup table may be stored on the controller and may be calibrated or updated, for example, by a user.

[0070] Optionally, the cancellation signal is configured to reduce the cogging torque of the motor.

[0071] Optionally, the frequency of the household appliance is determined from household appliance characteristics, the characteristics including any one or more of the following: motor size, motor toothing, drum volume, diameter, depth, fan size, motor type and / or load size, load type or load weight. Optionally, a subset of the characteristics is selected.

[0072] Optionally, the step of combining the motor control signal and the cancellation signal comprises any one or more of: adding the signals, or mixing the signals. Optionally, electrical components are used to combine the signals.

[0073] Optionally, the motor control signal is a vector controlled motor control signal.

[0074] Optionally, the cancellation signal is applied to the motor torque control signal.

[0075] According to another aspect, the present invention can be broadly described as a household appliance, the household appliance comprising:

[0076] a load; a motor configured to operate the load, and a controller configured to: obtain a motor control signal configured to control the speed of the motor,

[0077] obtaining a cancellation signal configured to reduce the noise or vibration of the household appliance,

[0078] combining the motor control signal and the cancellation signal to form a combined signal, and

[0079] The combined signal is applied to the motor.

[0080] Optionally, the household appliance further comprises a sensor, which is configured to obtain a measurement value, wherein the controller is configured to obtain the cancellation signal based on the measurement value.

[0081] According to another aspect, the present invention can be broadly described as a controller for a household appliance, the controller being configured to:

[0082] obtaining a motor control signal configured to control the speed of the motor of the household appliance, obtaining a cancellation signal configured to reduce the noise or vibration of the household appliance,

[0083] combining the motor control signal and the cancellation signal to form a combined signal, and

[0084] The combined signal is applied to the motor.

[0085] Optionally, the household appliance and / or a controller for the household appliance is configured to implement any one or more of the optional aspects of the first aspect.

[0086] Optionally, the cancellation and / or motor control signal is either a voltage or a current, and preferably a voltage. The vector control system may include a DQ0 control system, wherein the cancellation signal may be combined with Vdx and / or Vqx. Preferably, all or at least the larger signal is applied on Vqx. Optionally, the motor is a permanent magnet synchronous motor. Optionally, the motor is a brushless DC motor. Optionally, the household appliance is a washing machine. Optionally, the household appliance is an extractor unit or a range hood. Optionally, the motor load is a rotating load.

[0087] According to another aspect, the present invention may be broadly described as a method of operating a motor driving a load in a household appliance, the method comprising the steps of:

[0088] Determining a first frequency of a first noise component generated by the household appliance at a first speed, determining a second noise component having a frequency equal to the first frequency but having a phase offset from the first noise component; determining parameters of an injection signal configured to drive the motor and / or the load to generate the second noise signal; and applying the injection signal to the motor.

[0089] Optionally, the phase shift is 180 degrees. Optionally, the injection signal is a torque signal.

[0090] The present invention may also be broadly described as including, individually or collectively, the parts, elements and features mentioned or indicated in the specification of the present application, as well as any or all combinations of any two or more of the parts, elements or features, and where specific integers having known equivalents in the art to which the present invention relates are mentioned herein, such known equivalents are deemed to be incorporated herein as if individually set forth.

[0091] The term "comprising" as used in this specification and claims means "consisting at least in part of..." When interpreting each statement in this specification that includes the term "comprising", there may also be features other than the features beginning with this term. Related terms such as "include" and "containing" are to be interpreted in the same manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 A cross-sectional view showing a cleaning machine

[0093] Figure 2 Showing a cross section of a horizontal cleaning machine

[0094] Figure 3 Showing a cross section of an inclined cleaning machine

[0095] Figure 4 Schematic diagram showing a cleaning machine

[0096] Figure 5 Schematic diagram showing a cleaning machine

[0097] Figure 6 A control system diagram showing a motor of a washing machine, for example

[0098] Figure 7 A control system diagram showing a motor of a washing machine, for example

[0099] Figure 8 A control system diagram showing a motor of a washing machine, for example

[0100] Figure 9a A control system diagram showing a motor of a washing machine, for example

[0101] Figure 9b Shows the application Figure 9a The control algorithm of the control system.

[0102] Fig.10 shows the speed vs. noise graph for a system without noise cancellation

[0103] Fig.11 Speed ​​versus noise plot for the system with noise cancellation is shown.

[0104] Fig.12 A cross-sectional view of an extraction unit or a range hood is shown.

[0105] Fig.13 A schematic diagram of an extraction unit or a range hood is shown.

[0106] Fig.14 Speed ​​vs. noise graph showing a range hood system without noise cancellation

[0107] Fig.15 Speed ​​versus noise graph for a range hood system with noise cancellation is shown. DETAILED DESCRIPTION

[0108] When there is an excitation source and another aspect of the system resonates with the noise source, undesirable noise and / or vibration may be caused. In many household appliances, some noise is unavoidable because the appliance needs to be operated effectively. However, in other cases, the resonance between the vibration generated by the motor and a part of the appliance produces undesirable noise. The noise can be improved by reducing the vibration generated by the motor. The described method is applicable to a range of household appliances, and a washing machine is always used only as an example. Appliances include washing machines (including dryers and multi-function machines) and household or home appliances.

[0109] For example, a cleaning machine or washing machine has an excitation energy or drive for the machine generated by a motor. Potential resonant components are other parts of the cleaning machine, in particular loads attached to the rotor or drive shaft. If the motor frequency (or harmonics of the motor frequency) operates at or near the resonant frequency of the machine or a part of the machine, the excitation of the motor may resonate with the machine, thereby amplifying the noise. For example, the rotation of a tub or drum may resonate with torque fluctuations in the field of the motor. Identifying these one or more frequencies (i.e., frequencies that generate unwanted noise) allows the method to improve the noise.

[0110] Noise can be reduced or improved by avoiding excitation at the resonant frequency of the machine, or by trying to pass through the resonant frequency quickly. However, this may be difficult if the resonant frequency is at or attached to an important frequency for operation. For example, there may be a spin speed of 93 RPM that resonates with the drum. Damping or adding absorbing materials to the appliance can reduce the effects of resonant excitation, but these require additional components. Changing the machine design to change the resonant frequency can also reduce noise, such as improving the motor design to reduce the excitation frequency or torque fluctuations.

[0111] It has been found that manipulating motor control signals is a non-mechanical way to reduce torque fluctuations and counteract noise in household appliances (such as washing machines). A motor control signal is a signal provided to a motor or a control motor that controls or adjusts the electrical power provided to the motor. The motor control signal typically controls the speed of the motor. Providing a suitable drive signal to the electric motor (by adding a noise cancellation signal to the desired control signal) can actively eliminate the noise or vibration generated by the washing machine during operation. It has been found that manipulating the motor control signal at or near a specific resonant frequency (measured or sensed) of the machine or household appliance allows noise and / or vibration to be eliminated or at least mitigated. This is similar in part to active noise cancellation (ANC) as used in audio equipment, where a phase-shifted copy of the incoming noise is used to destructively interfere with and hopefully eliminate the noise providing improved audio performance. However, because the motor-driven appliance is not specifically driven for audio output, the noise signal cannot be used directly.

[0112] In motor control, a base current, signal or excitation is provided to the motor in order to control the speed of the motor by generating torque. One or more loads attached to the motor (when the motor is activated, directly or through a drive shaft, belt, transmission or other arrangement are caused to operate or move) are in turn driven by the rotation of the motor rotor. The base excitation frequency will be selected to generate the required output from the appliance. However, torque fluctuations can be introduced into the motor along with the base current through cogging torque or other means. In some cases, this torque fluctuation excites the resonance of other parts of the load or machine to cause unwanted noise. Although the noise caused by the base excitation cannot be eliminated without reducing performance, it is possible to eliminate the noise caused by torque fluctuations in some cases.

[0113] For the example of a washing machine, the primary load is the laundry drum (although there may also be other loads or components that are capable of resonance). One or more signals (the signals may be additional voltages or currents, or other electrical signals) are added or injected onto the base current or drive current (or other signals that drive the motor operation) to generate another field in the motor windings (on top of the field generated by the base current). If the injected signal is appropriately selected, designed or generated, the field generated by the injected signal can cancel the field in the motor. In particular, the injected signal can cancel the noise generated by the machine by reducing or eliminating the field in the motor that generates vibrations. If the cancellation is sufficient, noise caused by vibrations generated by the motor (directly or indirectly) can be avoided or improved because the cause of the vibration (the frequency or excitation of the motor) has been modified.

[0114] The injection signal is preferably relatively small relative to the drive signal. This avoids efficiency losses (because the injection signal is not intended to drive the output of the motor). In a typical system, the drive voltage can be between 250 volts and 300 volts, and the injection signal can be between 0 volts and 20 volts, more preferably between 0 volts and 15 volts, more preferably between 5 volts and 15 volts, and more preferably between 8 volts and 12 volts. This is equivalent to an injection signal between 0% and 10% of the drive voltage, more preferably between 1% and 6% of the injection signal, and most preferably between 2% and 4% of the injection signal. The injection signal can be referred to as an injected torque because it is typically a fluctuation in the motor torque that causes the vibration, although adjustments of non-torque fields are also possible.

[0115] Relevant frequencies in household appliances, such as resonant frequencies, can be measured or tested or otherwise identified. For example, a sweep test across a motor or speed range can be performed, and measurements (such as audio measurements of noise, accelerometer measurements of vibration, electrical measurements, or other noise measurements) can be performed to identify resonance or potential resonance. The range can be the entire operating range (0 to maximum rpm) or can be a more limited range, or multiple ranges of known problems. Resonance can be determined based on one or more center or dominant frequencies of the noise generated by calculation (e.g., those frequencies with the highest intensity noise or noise that is noticeable to the user). Alternatively or similarly, resonance can be determined by or with reference to the frequency (or RPM (revolutions per minute)) of the motor. In some cases, a known relationship can be used to convert from motor frequency (rpm) to resonant frequency.

[0116] Household appliances or motor-driven appliances typically have a dominant resonant frequency at at least one excitation frequency or speed (rpm). Household appliances can have different resonances depending on the speed, and in some cases, there can be multiple resonances at the same speed (for example, there are resonances for multiple harmonics, or there are resonances that produce different noises at multiple different speeds). If the load on the motor changes, this may affect the resonance. In some cases, this can be positive because the change in load can help dampen the resonance. However, in other cases where the load change requires more motor torque, this may exacerbate the resonance. Feedback or recalibration of the control system can solve these problems.

[0117] Household appliances may operate at frequencies where effective noise cancellation is not possible. For example, if resonance and / or noise occurs at the drive frequency of a motor, adding a noise cancellation signal at that frequency will reduce the effective operation of the motor. Therefore, it may be advantageous to have a set, group, or range of frequencies where noise cancellation does not occur. The set of frequencies may include typical drive frequencies for the motor.

[0118] Once one or more frequencies that generate unwanted noise or resonance have been identified, calculated or selected, a cancellation signal can be generated. The phase and amplitude of the signal injection should be calculated to best improve the noise. However, unlike audio noise cancellation, it is not always direct to generate a signal that is out of phase with the detected noise. This is because the required signal such as depends on the detected noise, but must be generated by the motor. This means that the injection signal must take into account the transfer function or signal transformation between the position where the signal is injected and the motor output (which will include the motor itself). Therefore, an injection signal or cancellation signal must be obtained, which is configured so that the motor generates an output suitable for reducing the noise that generates resonance. Unfortunately, the noise generated by the motor is sensitive to the injection signal; due to the general structure of the motor (such as the number of rotor and / or stator poles) and changes in the motor construction. This makes it difficult to provide a general transformation from detected noise to injection signals, even for very similar or substantially identical motors.

[0119] The motor speed that generates the undesirable noise can be measured. The motor speed or frequency can then be converted into the electrical frequency of the motor. For a permanent magnet motor, the speed is equal to 120*(number of poles) / (electrical frequency Fe). For a permanent magnet motor running at 270rpm in a 36-pole motor, the electrical frequency is 36*270 / 120~81Hz. The noise may be driven by harmonics of the electrical frequency, such as the third, fifth or seventh harmonics. This means that the electrical frequency should be multiplied or adjusted to attenuate the specific harmonic. Most commonly, the cogging torque with a frequency equal to the third harmonic frequency will be the cause of the noise because it is the largest harmonic in some motor configurations. Therefore, the frequency of the signal to be injected will be three times the electrical frequency (e.g., 243Hz). Alternatively, frequency analysis of the noise generated by the motor across frequency scanning (or at multiple frequencies of interest) can be used to identify the peak noise frequency at each rotation frequency. In some cases, one or more frequencies or harmonics can be eliminated, or the harmonics to be eliminated can be selected based on existing knowledge of motor and / or electrical resonance. The selection of frequencies can be by isolating or selecting one or more frequencies that produce relatively high noise levels. This can be the case where a specific frequency of the noise has a peak, or where the total noise has a peak (global or local maximum noise level), or simply the frequency at which good noise cancellation is possible. Relatively high can be measured as a comparison of the total noise level (dB) or noise intensity or other techniques.

[0120] In some implementations, a lookup table or database may be created to associate the phase / amplitude or coefficient of the signal injection to be used. One or more lookup tables are stored relationships between signal parameters and known, measured, or available parameters. For example, they may link measured noise to signal parameters, or motor parameters to noise parameters. The association may be based on any one or more of the motor speed, electrical signal, current, voltage, motor type, and physical parameters of the appliance. The lookup table may be stored in a memory on the controller. The database may be calibrated to be accurate for a particular machine. However, it has been found that the phase of the injected signal required to reduce noise (where the phase is preferably relative to the electrical angle (θ) of the motor) may be more accurate than the phase of the injected signal required to reduce noise. E ) measurement) is often variable or sensitive to small variations between motors. That is, it can be highly dependent on the specific motor used and sensitive to small variations in the geometry of the motor parts (i.e., within manufacturing tolerances). Although in some cases, the choice of relative to the current θ E A fixed phase difference (e.g., 180 degrees) or relative to the noise generated may be sufficient, but the appropriate phase must typically be tuned, configured, or calibrated for the specific motor type or for each individual motor.

[0121] Table 1 shows a series of exemplary successful cancellation (injection) signals for a range of similar cleaning machines and motors and rotational speeds. While the amplitude of the signal is essentially constant, the phase angle is more sensitive in the range between 10 volts and 12 volts for a drive signal of 250 volts to 300 volts. Therefore, the system can have a device for adjusting the phase angle of the cancellation signal. This can be performed as a configuration of the machine (i.e., based on initial testing or maintenance checks), or a closed loop tuning method or optimization can be used (e.g., performing a search across possible phase angles and selecting the phase angle that provides the best noise cancellation). In some systems, a 2 or 3 dimensional optimization can be performed to optimize the amplitude and / or frequency (shown in Table 1 as relative to electrical frequency / θ E The harmonic orders of the signal parameters are listed). In some examples, one or more of the signal parameters are optimized and the remaining signal parameters are preconfigured, fixed or preset. More sensitive signal parameters (such as phase) are preferably optimized, while more stable parameters (specific frequencies) can be preconfigured. It is also possible to have multiple optimized parameters, although this may require additional controller calculations. The optimization can be based on sensor feedback or calibration testing at one or more or a range of parameter values. The parameters can be set relative to parameters previously used at different speeds or frequencies of the same appliance.

[0122] Configuration or calibration of the machine may involve a user, manufacturer, or maintenance / service personnel running a configuration test. The configuration test may provide an input signal of different phases at one or more frequencies (RPM) (or, with a calibration amplitude and / or frequency (harmonic order or other) alone or in combination) and receive feedback (or noise data) about the optimal noise cancellation point. The feedback may be by a sensor such as a microphone, or may be received by a user input such as a button or by a control application (e.g., a mobile phone application or other). The sensor (or sensors) may be located in or on the machine, including in or on the machine motor. Alternatively, the sensor (or sensors) may be on an external device (such as a personal computer, a mobile computer, or a mobile phone), and a user interface on the machine or external device may be used to confirm or select the optimal phase angle or configuration. Calibration may involve a sensor on the external device and a user input on the household appliance. There may be a communication line or component between the external device and the household appliance, including wireless or wired communication. The calibration parameters include any parameters of the injected signal, including any one or more of phase, amplitude, or frequency.

[0123]

[0124] Table 1: Noise cancellation for a range of cleaning machines

[0125] In the example of a washing machine, the drum is the main resonator, or if the drum resonates at the excitation frequency (or its harmonic) of the motor, the drum can cause the most noise. Therefore, the parameters of the drum (or the maximum or most resonant load selected) can be related to the parameters of the calculation or estimation of appropriate noise elimination injection signal or the signal. These parameters can include any one or more of the diameter, depth, total volume, orientation, material and / or weight of the drum. A combination of these parameters will usually be used. For different electrical appliances, the maximum rotating body or load connected to the motor or motor shaft may dominate the resonance that causes noise. For example, in an air conditioner or heat pump, the maximum rotating body will be a fan, for a range hood, it can be a fan similarly, for a dishwasher, it can be a propeller or a spray arm. In these cases, the parameters of one or more loads attached to or moved by a motor or drive shaft will be associated with the injection or elimination signal. These parameters can include any one or more of the material, size, weight or shape of the load and / or any related parameters listed for a washing machine.

[0126] Fig.10 Noise measurement data (in decibels) for a range of motor or drum rotation speeds between 0 rpm and 300 rpm are shown, similar to the noise measurement data that can be used for calibration. Other noise data can also be used, where it is possible to compare relative noise levels and / or identify peaks or high levels of noise. The noise is measured by microphones located in different areas of the machine. Measurements of microphones on or near the machine exterior 102, on or near the suspension assembly or suspension spring 101, and on or near the motor 103 are shown. The average value 104 of the noise generated is also shown. There is a significant noise peak at about 270 rpm. Therefore, this will be the frequency of interest. The calibrator can then determine that the noise generated is not due to the desired function. In this case, it is found that the noise is generated by a third harmonic torque fluctuation and can therefore be attenuated or reduced. As described above, the noise at 270 rpm in a 36-pole motor can be excited by the third harmonic of the electrical frequency of 216 Hz (existing knowledge can be used to identify very likely or possible harmonics or injection frequencies). Fig.11 The results are shown for injecting a cancellation signal at approximately 216 Hz with an amplitude of approximately 10 to 12 volts and an optimized or partially optimized phase. The noise is reduced by approximately 10 dB at all locations.

[0127] Fig.12An extractor unit 200 is shown that can be mounted above a cooker top and can include a hood 230 that contains rising cooking fumes and / or directs these fumes toward an extractor outlet and into an extractor duct 220. The hood 230 can have a T-shaped profile, wherein a portion of the hood 230 extends substantially parallel to the cooker top and is perpendicularly connected to the extractor duct 220. However, the hood 230 can alternatively have some other profile, such as an inclined profile (a portion of the hood extends at an angle relative to the cooker top, sloping downward from the rear of the hood to the front of the hood). Various other configurations of extractor unit hoods 130 suitable for use with the present invention are known in the art.

[0128] The extraction airflow may be driven by a blower or fan 210. The fan 210 may be housed within a hood 230 or within an end region of the extractor duct 220, or may otherwise communicate with the extractor duct 220 to draw the extraction airflow into the duct. In some implementations, the extractor duct 220 may include multiple duct sections connected together, or may include only regions or portions of duct sections.

[0129] Extractor duct 220 may include an outlet or be connected to an outlet or be communicated with an outlet, and extraction air flow 2 may be discharged through the outlet. In some specific implementations, extractor duct 220 may be a part of a pipeline network, be connected to a pipeline network or be communicated with a pipeline network. Extractor duct 220 may be communicated with a central pipeline network of a building (e.g., an apartment building), and extraction airflow 2 may be discharged through the vent of the building via the central pipeline network. The pipeline network may be communicated with a plurality of extractor units, and each extractor unit may be via corresponding extractor duct 220. Extractor unit 200 or range hood may include electric motor 250 to drive fan 210. For example, motor 250 may be accommodated above hood 230 beside fan 210, and may be coupled to fan 210 so that the rotation of motor 250 causes the rotation of fan 210.

[0130] Fig.13 It is shown that the extractor unit 200 may further include a controller 260 . Among other things, the controller 260 may control the motor 250 to drive the fan 210 .

[0131] For example, the controller 260 can control the speed (e.g., in RPM) of the motor rotation. The motor 250 can be controlled to drive the fan 210 in an attempt to achieve a desired flow rate (target extraction airflow flow rate) of the extraction airflow 2, which is expected to achieve sufficient extraction of cooking fumes from the cooking zone 3. The target extraction airflow flow rate can be, for example, between 6m3 / min and 20m3 / min. In some specific implementations, the target extraction airflow flow rate can be between 8m3 / min and 14m3 / min. The controller 260 can also be configured to receive and process inputs from various sensors 270, 280 of the extractor unit 1 and / or from the motor 250. Other designs of range hoods are known in the art.

[0132] The described method is generally applicable to other household appliances that are motor-driven or have motor-driven components, such as extractor units. The operation of motor 250 can excite the resonance in the range hood or extraction unit 200, and in some cases, these resonances produce noise that can be eliminated by the described technology. Similarly, for the washing machine example, there is noise that cannot be eliminated, such as operating the fan will produce noise, but reducing this noise will affect the overall performance of the motor. Therefore, one or more frequencies can be selected at each range hood fan 210 speed, and the torque fluctuation frequency (such as driving current harmonics) that produces these torque fluctuations can be calculated. Injecting signals to reduce these frequencies can reduce total noise. Sensors 270, 280 can be microphones associated with other places on or near the fan 210, motor 250 or in the extractor unit 200 to detect these resonances and allow calibration and / or closed-loop control.

[0133] Fig.15 Noise measurement data (in decibels) for a range of motor or fan rotation speeds for the extractor unit 200 is shown. The speed range is between 0 rpm and 140 rpm, similar to the speeds that can be used for calibration (although a selected frequency set or multiple selected frequencies can also be used). Other noise data can also be used, where it is possible to compare relative noise levels and / or identify peaks or high levels of noise. The noise is measured by microphones located in different areas of the machine. Measurements of microphones on the outside of the machine 201, on or near the fan 203, and on or near the motor 204 are shown. The average value 202 of the noise generated is also shown. There is a significant noise peak at about 110 rpm. Therefore, this will be the frequency of interest. The calibrator can then determine that the noise generated is not due to the required function of the extractor unit 200. We can calculate the noise at 110 rpm in a 36-pole motor, and the main excitation electrical frequency is 33 Hz. The third harmonic is selected as a potential cause of resonance, and a 99 Hz elimination signal can be used (existing knowledge can be used to identify likely or possible harmonics or injection frequencies). Fig.14The result of injecting a cancellation signal with optimized amplitude and phase is shown, with the noise reduced by more than 10 dB at 110 rpm.

[0134] Similar methods are applicable to other household appliances with motors driving fans. Dishwashers have motors (and typically combined or separate pumps) that are operated to rotate the spray arm so that water moves around the washer (and the pump moves the water through the machine). Refrigerators, freezers, and refrigerator freezers typically have motor-driven fans and motor-driven compressors. The described method can also be applied to household appliances with motors driving one or more loads, wherein the loads include one or more pumps, drive shafts, drums, fans, spray arms, or other loads for the operation of household appliances. There are multiple motors in several household appliances. Optionally, the method is used to reduce the noise generated by the first motor and the second motor (or multiple motors). This may require multiple microphones or calibration to determine which noise or resonance is generated by a specific motor. In another example, the motor only runs or operates a part of the machine. For example, an oven can have a fan mode operated by a motor. The noise of the fan mode can be reduced by the described method.

[0135] In some configurations, the motor controller uses vector control (or field-oriented control). In such a system, the three-phase motor control system is transformed into a coordinate system with two orthogonal components that rotate with the rotor flux vector. The two orthogonal components typically define the motor's flux (Dx) and the motor's torque (Qx). Field-oriented control allows high-performance motor applications to operate smoothly over the full speed range, generate full torque at zero speed, and have high dynamic performance including rapid acceleration and deceleration. In a vector control system, it is advantageous to apply the noise cancellation signal to the orthogonal axis (Qx, or torque axis) rather than the direct axis (Dx, stator flux axis). For example, an equivalent voltage applied to the Qx signal can reduce, eliminate or improve more vibration, and therefore reduce, eliminate or improve more noise than if it were applied to the Dx point. Applying the signal only at Qx can reduce the voltage required for noise cancellation (or injection into the signal). In an alternative system, the signal can be applied to both the Qx and Dx points, or applied to different control systems (such as stationary reference (α-β) or three-phase control). In the case of using a different control system, it may be necessary to modify the injection signal or the noise cancellation signal to provide a similar response to the signal injected at Qx. The required signal transformations between reference frames are known in the art. In some cases, it may be easier to discuss injecting a torque or torque signal into the motor. It will be understood that injecting an electrical signal configured to cause a torque or torque field in the motor is equivalent to injecting a torque signal.

[0136] In some configurations, the motor is a BLDC (brushless direct current) permanent magnet synchronous motor (PMSM). An exemplary motor to which the system can be applied is shown in US20180159394A1. However, the control system can be applied to other motors, including induction motors and synchronous motors. Due to differences between the mechanical and / or electrical characteristics of the motors, different motors may require changes in the injection signal. For example, the relationship between rpm and frequency will depend on the number of poles of the slip between the stator field and the rotor field in the induction motor.

[0137] Figure 1 A washing machine 31 is shown. The washing machine has a body 37 containing a motor 36, which is connected to a drum 32 by a drive shaft 34. In use, clothes or garments are placed in the drum, and the controller performs the required actions to clean or wash the clothes. Variations in this connection are possible, including the case of the direction in which the drum is connected to the motor rotor. The orientation of the drum is usually vertical or horizontal, although other orientations are also possible. Typically, manufacturers produce washing machines 31 of several sizes to allow different drum 32 sizes (and therefore different capacities) and to fit in different spaces. Changes in drum size and other parameters or characteristics of the washing machine will affect the resonant frequency of the machine and therefore affect noise generation. A control panel 33 is available to the user on the outside of the body 37. The control panel is shown on the top of the washing machine, but may be located elsewhere or may be obtained through an application. The control panel 33 provides input signals or instructions to the controller 38, which controls the operating mode or parameters of the washing machine 31. The controller 38 can be a computer or microcontroller or similar device capable of receiving input signals and sending instructions and / or timing signals to various components of the washing machine, as known in the art. Controller 38 may be located in or near control panel 33, or elsewhere within body 37. In some cases, controller 38 is formed from multiple components distributed across the machine.

[0138] Figure 2 A front loading horizontal axis washing machine 31 is shown having an outer package and a rotating drum housing 39 suspended in the outer package or body 37. The rotating drum 32 is disposed in the rotating drum housing and is rotatable within the rotating drum housing. A door 40 provides access to the rotating drum 32 for introducing or removing clothing to be washed. A gasket 41 may be included to provide a seal between the door and the rotating drum. The rotor is coupled to the rotating drum via a rotating shaft, and the stator is coupled to the rear of the barrel. The motor 36 is operable by a controller 38 to rotate and oscillate the rotating drum 32 to perform washing of the clothing. The cross-sectional view shows support features of the drum including supports 42 and damping or suspension springs 43. The motor 36 is used to rotate the drum, as shown in the figure, located Figure 2The bottom of the drum on the right side. Alternative placement of the motor 36 is possible, including the case where the motor is spaced apart from the drum and mechanically connected to the drum by, for example, a transmission or belt. In all cases, the machine can benefit from the noise cancellation described. In some specific implementations, resonances caused by the drum 32, the support 42, or the suspension spring 43 can be targeted by noise cancellation. One or more sensors or microphones at or near the drum 32, the support 42, or the suspension 43 can be used to isolate or target specific noises.

[0139] Figure 3 A top loading or tilt-in horizontal axis washing machine 31 is shown. The washing machine has an outer package (not shown) and a tub 39 suspended within the outer package. A rotary drum can rotate within the tub. Clothes can be introduced into and removed from the rotary drum through an opening 40 at the top of the drum. A motor 36 including a stator and a rotor is arranged to drive the rotary drum via a rotating shaft. The motor can be operated by a controller 38 to rotate and oscillate the rotary drum to perform washing of the clothes. Similar to Figure 2 , resonances can occur across the machine 31. These include at the support or suspension locations (or where the drum is attached to the frame) and at the drum itself.

[0140] In some cases, it is advantageous to mount the microphone or sensor on a household appliance. Figure 2 and Figure 3 For washing machines of this type, sensors (such as microphones) may be mounted on any one or more of the motor 36, drum 32 or tub 39, support 42, suspension support 43 or springs, or elsewhere inside or outside the machine 31. It may be advantageous to have multiple sensors, for example to determine where a particular sound or noise is generated, or to compare internal and external noise (noise in the external environment). The sensor may be a microphone, transducer, vibration sensor, accelerometer, or other device that provides an indication of noise generation.

[0141] Figure 4 The control features of a washing machine are shown. The washing machine has a drum 32 located in a tub 39 inside a machine body or housing 37. The drum 32 is configured to rotate or oscillate during the laundry washing process. The drum 32 is typically mounted or suspended inside the housing by a suspension assembly. The suspension assembly may include one or more supports 42 and / or one or more spring mounts 43. The drum may be inside a package or drum housing 39 that is suitable for holding water inside the drum 32 or supporting the drum while rotating. The suspension assembly may then be attached to an outer package that holds the drum. The drum is excited or moved by a motor 36. The motor may be of various known types, but is preferably a BLDC PMSM. The motor is controlled by a motor controller 38.

[0142] One or more sensors may be attached, mounted to or associated with the cleaning machine. For example, the motor sensor 45 may provide measurements of motor parameters, including any one or more of electrical angles, mechanical angles, motor current and voltage. Noise and / or vibration sensors may also be positioned across the machine. In particular, Figure 4 A noise or vibration sensor 46 is shown mounted or located within the body 37 . Figure 5 A similar arrangement of a washing machine is shown, but with a noise or vibration sensor 47 mounted on or near the drum 32 or tub 39. In other systems, the sensor or additional sensors are mounted on the outside of the washing machine 31. A system can have multiple sensors 46, 47 mounted in different locations. The preferred location depends on the expected noise generating components and the ease of placing the sensor. For example, it is easier to place the sensor on the current PCB or controller (or controller part) than to attach or fix the sensor in a new location. In some specific implementations, the controller 38 may include multiple parts or PCBs distributed around the washing machine. For example, there may be a separate PCB for the motor controller 38. Although the system has been illustrated with a variant of a washing machine, it should be understood that similar systems can be constructed in other household appliances, where the motor will be connected to or associated with one or more different loads that require different configurations or sensor placement.

[0143] The motor controller 38, or the portion of the controller 38 that controls the motor 36, is configured to control the operation of the motor 36 to meet the requirements set by the user. Typically, this means controlling the rotational speed (ω) of the motor 36 (and therefore the drum 32). R The main control system or algorithm will typically receive the desired spin speed ( and the measured motor position and speed (θm,ω R ), appropriate motor drive signals (e.g., Vd* and Vq*) can then be calculated, as is known in the art, such as vector or field oriented control algorithms.

[0144] Figure 6 A motor control implementation is shown, where the main control algorithm 20 takes the input control signal 25 as well as the motor position θ and the motor speed ω R The control algorithm 20 calculates the vector control signal V d * and V q *, which can be transformed into an α-β frame (or a stationary reference frame) by a transformation algorithm 21, such as the Clarke algorithm, and then converted into an input signal (V a , V b , V c) to a three-phase motor 36 that drives or excites a load 9. Other means of applying, associating, or communicating the combined signal to the motor may be used. The control signal (θ (electrical position, also referred to as θ E ),ω R ) can be obtained by a position estimator or measuring device 23. This can be obtained from sensors on the motor (e.g., providing position measurements (θ m )) or obtain input from an electrical sensor (such as a voltage or ammeter) on the input signal.

[0145] Figure 6 An additional ANC (active noise cancellation) algorithm controller 24 is also shown. This control algorithm provides noise and / or vibration cancellation to the overall controller. In an exemplary open-loop control system, the ANC algorithm 24 receives the motor position and motor speed (θ, ω R ) as input and includes the calculation of a suitable noise cancellation signal (V ds * and V q s*) of the motor 36. These noise cancellation signals are summed or combined with the vector control signals at combiners 27, 28. When transformed and passed to the motor 36, the noise cancellation signal (V ds * and V q s*) changes or modifies the torque in the motor in order to shift or reduce the frequencies or harmonics that cause resonance or noise. In some variants, there may be only one connected to the vector control signal V d * and V q * A single output signal of one of the noise cancellation signals. In addition, the relative size, voltage range or strength of the noise cancellation signal can be varied. In particular, it has been found that when applied to V q *, the relative effect of voltage is greater because this applies the voltage directly to the torque producing components.

[0146] Preferably, the noise cancellation signal (V ds * and V q s*) is a sinusoidal signal, such as a voltage, which is the electrical position θ of the motor E function of. The advantage of the noise cancellation signal being a sinusoid is that the amplitude, phase (relative to each other and / or relative to the motor signal) and frequency provide a set of parameters that can be varied to provide an optimal noise reduction signal to the motor. The use of a sinusoidal signal (or sine waves) also means that injection signals of varying shapes can be formed by combinations of sine waves, for example in the case of improving two noise frequencies simultaneously. Each component signal can follow the described method and be combined with the motor control signal at the same or different points.

[0147] Figure 7 shows the addition of closed-loop feedback 8 and Figure 6 Similar motor control system. Figure 7 The core operation of the controller is similar to Figure 6 The core operation of the controller of , however, sound or audio feedback 18 can now be obtained from the load. Although it is expected that the main load (e.g., the drum of the washing machine) will be the main generator of noise in other systems, in the presence of further resonance, the noise from the wider machine can be recorded. The sound feedback 18 can be obtained from a microphone or other suitable sound recording device or equipment. Preferably, the microphone is located at or near the motor so that it records noise close to the motor or main resonator, and can therefore better measure or "sense" the motor noise. However, the microphone can also be located remotely, such as on the load or on the control panel 33. In these cases, the sound or audio signal can be transmitted to the motor controller 38 via wiring or other known communication technologies. In some cases, multiple microphones are used to improve noise collection or target multiple noise locations. In a specific embodiment, the microphone is configured to detect vibrations or noises of the washing machine or household appliance, which are caused by the motor and amplified by the washing machine system. Although the sound feedback 18 has been described, it is clear that a sensor indicating sound or vibration can be used alternatively.

[0148] The sound or audio feedback 18 received by the active noise cancellation algorithm is used to determine the appropriate correction signal (V ds * and V q s*) to be combined into the motor drive signal. The signal can be combined by direct or through component electrical connection. By adjusting the parameters of the applied injection signal or noise cancellation signal and monitoring the noise of the machine, the feedback 18 will indicate the noise of the machine, and the parameters of the injection signal that provides the most effective noise cancellation can be obtained. For example, the phase of the injection signal (relative to the electrical position of the motor) can be adjusted between 0 and 360 degrees. This can be used to identify the most effective noise cancellation frequency. If additional knowledge about the expected phase is known, the range can be reduced. At the same time, before or after calculating the phase, the amplitude can also be calculated. Preferably, this will occur simultaneously with the phase or after the phase because the noise appears to be less sensitive to the amplitude. The frequency of the injection signal can be calculated based on the motor or drum rotation speed. For example, the rotation speed can be converted into an electrical frequency and one or more harmonics (such as the 3rd, 5th, 7th) of the selected electrical frequency. The selection of harmonics can be based on existing knowledge of which harmonics cause noise in specific electrical appliances.

[0149] More complex feedback systems are also possible. For example, spectral analysis (such as the Fourier spectrum or FFT of the noise signal) can be used to identify the largest frequency components of the acoustic feedback 18. These can be converted to motor frequencies or compared to the motor frequencies to identify the specific harmonics causing the noise. The correction signal (V ds * and V qs*) can then be configured to change the motor frequency so that the motor is not excited at the noise frequency. The configuration may include performing a local or global optimization of the amplitude or phase of the injected signal at the calculated frequency. In the case of the calculated frequency, there may be one or more frequencies or segments of the spectrum that are not used. These will be selected to avoid trying to eliminate noise at the operating frequency. For example, the noise generated by the rotation of a drum or the movement of fan blades through the air is unavoidable, and the use of noise cancellation at these frequencies may reduce the efficiency of the appliance.

[0150] Figure 7 The control system allows for a closed loop control system in which the control system constantly monitors itself (using a microphone or audio transducer, or any other noise or vibration sensor). If a resonance is detected in the sensed measurements, a suitable cancellation signal can be generated and applied. Ignoring some resonances may be useful, for example where attempting to reduce resonances would adversely affect the performance of the washing machine. This may occur if the resonance is at a center operating frequency (i.e., the drum excitation frequency). A range, multiple ranges, or a collection of one or more ranges of allowed and / or disallowed frequencies for the noise cancellation signal may avoid this problem.

[0151] Figure 8 It is shown that alternative transducers or sensors can be used. In particular, instead of using a microphone to feedback noise, a vibration sensor (such as an accelerometer) can be used to sense vibrations in or of the washing machine. Electrical sensors can also provide feedback. Figure 8 The closed loop feedback signal is shown as 8, which is the vibration signal 17 or feedback. Incorporating a vibration sensor into the control algorithm is similar to acoustic feedback, simply requiring an additional or alternative sensor and the ANC algorithm 24 must be adapted to the vibration. In a similar manner to the acoustic sensor, the spectrum or dominant frequency of the vibration feedback can be used to generate a suitable noise cancellation signal (V d s* and V q s*).

[0152] Figure 9a and Figure 9b Another implementation is shown where feedback from the system is used with no additional sensor requirements (ie, only the intended sensors on the motor measure the motor position θm and electrical signals such as Ib and Ic). Figure 9a The entire control system is illustrated, which is similar to Figure 7 and Figure 8 A suitable control algorithm or method may be connected from any measured signal to one of the injection signal points 27, 28 or elsewhere on the motor control signal. Figure 9bIt is shown how suitable injection signals (Vds* and Vqs*) can be generated. An error minimization algorithm 90 is used to derive one or more cancellation signals (e.g., Vds* and Vqs*, or Vqs* alone, although fixed or three-phase signals may also be generated). The error minimization algorithm 90 calculates the signals required to minimize the calculated error signal. One or more signals are combined to form an error signal (ε). Each of the one or more signals can be generated based on motor sensor measurements. Electric motor measurements include voltage and current measurements and motor electrical position. Position measurements, such as motor mechanical position or speed, may also be used. In some cases, signals or measurements from a motor controller (such as drive signals or voltages) may also be available.

[0153] The harmonics present on the motor 36 may be calculated or measured using motor measurements or signals. Figure 9b A Park transform 91 is shown for generating the error signal (in this case, the Park transform 91 is inverted, or stated from the alpha / beta fields using an inverse Park transform 91). When harmonics of the motor electrical frequency θ are applied to the Park transform 91, the motor current harmonics of the same electrical frequency are converted to a DC component output 92 (along with the expected AC signal). By filtering and / or calculating the DC output 92 of one or more Park transforms 91, torque ripples at harmonics or frequency multiples of the electrical frequency of the motor 36 can be obtained.

[0154] For example, if we know that the 3rd and 5th harmonics of the motor current are the cause of noise at a particular motor 36 or drum 32 speed or rpm, we can use the electrical positions (θselected1, θselected2) of the 3rd and 5th harmonics to generate two error signals. By minimizing these error signals, the noise in the system will be reduced. The input to the Inverse Pike algorithm 91 is the motor current. In Figure 9, the current in a fixed phase (α, β) is used. Although a single harmonic (or input signal based on the motor electrical angle or speed) can be used, multiple signals (e.g., N signals up to θselected'N') can also be used. These signals can be generated by multiples of the basic electrical angle (integer or other).

[0155] Although a sensorless system has been described using a Parker transform 91 (used inversely), any algorithm capable of providing a signal representative of the torque fluctuation or a component thereof (such as cogging torque) may alternatively be used. Alternative signals may be generated from other parameters such as motor voltage, mechanical position or drive signals. A suitable transformation is required to generate an error signal based on the available signal, which error signal is dependent on or indicative of the noise generated by the household appliance. This is possible because the motor provides the excitation for the noise, so knowing when the motor excitation will resonate with a component of the appliance, undesirable harmonics can be predicted and the described method used to reduce or eliminate the undesirable harmonics.

[0156] The choice of the order or multiples to be minimized (both the number of orders and the multiples of the fundamental electrical frequency) can be a design choice based on experimentation, such as determining which orders contribute most to the minimization of audible noise in a product containing a motor and load assembly. Given the general operation of the control system, the electrical measurements from the motor (current measurements Iα, Iβ) contain an indication of the vibration (and therefore noise) caused by the motor on the load (because the load is connected to the motor, the vibration of the load causes the vibration of the motor). If the algorithm minimizes any current / motor frequencies of a different order than required on the main control algorithm (the basic algorithm), they can be minimized by the algorithm, and therefore, the audible noise caused by them can be minimized accordingly.

Claims

1. A method for reducing noise of a household appliance, the household appliance comprising a motor, the method comprising the following steps: obtaining a motor control signal configured to control the speed of the motor, obtaining a cancellation signal configured to reduce the noise of the household appliance, The motor control signal and the cancellation signal are combined to form a combined signal, and the combined signal is applied to the motor.

2. The method according to claim 1, wherein the step of obtaining the cancellation signal comprises the following steps: identifying one or more frequencies of the household appliance; and A cancellation signal is calculated based on the one or more frequencies.

3. The method of claim 2, wherein the step of identifying one or more frequencies comprises the steps of: One or more frequencies, or load rotational speeds, are identified at each of the one or more motors.

4. The method according to any one of claims 2 or 3, wherein the cancellation signal is configured to reduce motor excitation of the identified one or more frequencies.

5. The method according to any one of claims 2 to 4, wherein the step of calculating the cancellation signal comprises the following steps: Harmonics of the electrical frequency associated with each of the identified frequencies are calculated or selected.

6. The method according to any one of claims 2 to 5, wherein the step of identifying the one or more frequencies comprises: A noise level of the household appliance is monitored for a plurality of motor speeds.

7. The method according to any one of claims 2 to 6, wherein the step of identifying one or more resonant frequencies comprises any one or more of the following steps: driving the motor at a plurality of motor drive frequencies or speeds; measuring the noise of the appliance at each of the plurality of frequencies or speeds; and Identify frequencies where the noise level is high relative to adjacent frequencies.

8. A method according to any one of claims 2 to 7, wherein at least one or each of the one or more frequencies is a resonant frequency.

9. The method according to any one of claims 1 to 8, wherein the cancellation signal comprises a sinusoidal signal or a plurality of component sinusoidal signals.

10. The method according to any one of claims 1 to 9, wherein the step of obtaining the cancellation signal comprises any one or more of the following: Obtaining the phase of the cancellation signal, obtaining the amplitude of the cancellation signal, The frequency of the cancellation signal is obtained.

11. The method according to claim 10, wherein the step of obtaining the cancellation signal comprises: obtaining the phase, amplitude and / or frequency of multiple component signals, and The plurality of component signals are combined to obtain the cancellation signal.

12. The method according to any one of claims 10 or 11, wherein the amplitude of the cancellation signal is 2% to 5% of the amplitude of the motor control signal.

13. The method according to any one of claims 10 to 12, wherein the step of obtaining the phase of the cancellation signal comprises any one or more of the following steps: loading the stored phase for the cancellation signal, testing one or more potential phases and selecting a phase from the tested phases, testing one or a series of potential phases and selecting a phase from the tested series of potential phases, Test a range of phases and use an optimization function to select the best phase, adjusting the phase based on feedback from the household appliance, and / or The phase is adjusted based on sensor measurements from the home appliance.

14. The method according to any one of claims 10 to 13, wherein the step of obtaining the phase and / or amplitude of the cancellation signal comprises the following steps: One or more sensor measurements are used to adjust the phase and / or the amplitude.

15. The method of claim 14, wherein each of the one or more sensor measurements is any one or more of an audio measurement, a noise measurement, an electrical measurement, and / or a vibration measurement.

16. The method of any one of claims 14 or 15, wherein each of the one or more sensor measurements is associated with any one or more of: The motor, the load, or External environment.

17. The method according to any one of claims 1 to 16, wherein the step of obtaining a cancellation signal comprises the following steps: calibrate the signal removal function, and A cancellation signal is generated based on the cancellation signal function.

18. The method of claim 17, wherein the step of calibrating the signal cancellation function comprises the steps of: obtaining noise data of the household appliance, and Signal parameters for the cancellation signal are obtained at one or more frequencies.

19. The method of claim 18, wherein the signal parameters include any one or more of phase, amplitude or frequency.

20. The method of claim 19, wherein the signal parameters of amplitude and / or frequency are preconfigured and the signal parameter of phase is configurable.

21. The method according to any one of claims 18 or 20, comprising the steps of: The cancellation signal function is recalibrated.

22. The method according to any one of claims 18 to 21, wherein the step of obtaining noise data comprises the following steps: Noise generated by the household appliance at a plurality of frequencies is sensed.

23. The method of claim 22, wherein the sensing is performed by a sensor, such as an audio sensor or a vibration sensor.

24. The method according to any one of claims 1 to 23, wherein the step of obtaining the cancellation signal comprises: Get feedback signals, and The cancellation signal is generated based on the feedback signal.

25. The method of claim 24, wherein the feedback signal represents any one or more of the following: The operating parameters of the machine; Noise and / or vibration of components of the household appliance; and Noise and / or vibration of the household appliance.

26. The method according to any one of claims 24 or 25, wherein the feedback signal is any one or more of the following: electric signal; Audio signal; Vibration signal; Error signal.

27. The method according to any one of claims 1 to 26, wherein the step of obtaining the cancellation signal comprises: Identify noises generated by motor-driven household appliances, and A cancellation signal is calculated that is configured to reduce excitation of a motor frequency that generates the noise.

28. The method of claim 27, wherein the step of calculating a cancellation signal comprises any one or more of the following: Lookup table, A lookup table that links the undesired noise parameters to the cancellation signal parameters, Link the motor parameters to a lookup table of cancellation signal parameters, Minimize the feedback signal, Minimize audible feedback, and / or Minimize vibration feedback signals.

29. The method of any one of claims 1 to 28, wherein the cancellation signal is configured to reduce the cogging torque of the motor.

30. The method of any one of claims 2 to 8, wherein the frequency of the household appliance is determined from household appliance characteristics, the characteristics comprising any one or more of the following: Motor size, Motor toothing, Drum volume, diameter, depth, Fan size, Motor type, and / or Load size, load type or load weight.

31. The method according to any one of claims 1 to 30, wherein the step of combining the motor control signal and the cancellation signal comprises any one or more of the following: Add the signals, or The signals are mixed.

32. The method of any one of claims 1 to 31, wherein the motor control signal is a vector controlled motor control signal.

33. The method of claim 32, wherein the cancellation signal is applied to a motor torque control signal.

34. A household appliance, comprising: load, a motor configured to operate the load, and A controller, the controller being configured to: obtaining a motor control signal configured to control the speed of the motor, obtaining a cancellation signal configured to reduce noise or vibration of the household appliance, combining the motor control signal and the cancellation signal to form a combined signal, and The combined signal is applied to the motor.

35. The household appliance of claim 34, further comprising a sensor configured to obtain a measurement value, wherein the controller is configured to obtain the cancellation signal based on the measurement value.

36. A controller for a household appliance, the controller being configured to: obtaining a motor control signal configured to control the speed of a motor of the household appliance, obtaining a cancellation signal configured to reduce noise or vibration of the household appliance, The motor control signal and the cancellation signal are combined to form a combined signal, and the combined signal is applied to the motor.

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