Method and computer program for controlling a fan of a household appliance and household appliance

Abstract

The present invention relates to a method for controlling a fan of a household appliance, wherein the fan comprises a motor and a control unit. The method is characterized in that the quality of the motor is determined, and the fan is controlled depending on the determined motor quality. A computer program product and a household appliance are also described.

Description

The present invention relates to a method and a computer program, in particular microcontroller software, for controlling a fan of a domestic appliance and to a domestic appliance having a fan.In household appliances, such as a vapor extraction device, a fan, which can also be referred to as a fan or fan, is used. This can be used in particular in an extractor device for sucking in the steams and vapours formed during cooking in the extractor device. In particular, the fan wheel of the fan is driven in the fan by a motor.In household appliances, for example extractors, electric motors are preferably used for the fan. Tolerance fluctuations of the electric motors result in fluctuations in the delivery volume and the power consumed. Domestic appliances must be provided with energy labels, for example, in the European union, or they must be classified into corresponding classes of the regulations of the energy labels. Due to the fluctuations of the electric motor, it is therefore possible that a fan or the household appliance in which the fan is used must be considered to be a poorer energy class. Alternatively, from fans in which the electric motors are used, the fans must be selected which can be reliably attributed to the corresponding energy class, while the unsuitable fans must be sorted out.Selection of fans according to their quality results in higher costs and resource waste due to waste.It is therefore an object of the present invention to provide a solution which reduces or eliminates the disadvantages.According to a first aspect, the present invention therefore relates to a method for controlling a fan of a domestic appliance, wherein the fan comprises a motor and a control unit. The method is characterized in that the quality of the motor is determined in the method and the fan is controlled as a function of the determined motor quality.The household appliance represents in particular a kitchen household appliance, such as for example a vapor extraction device, a refrigerator or a vacuum cleaner. The domestic appliance is preferably an extractor device. A extractor device can be, for example, an extractor hood or a trough fan. In a refrigerator, the fan serves as a compressor, for example. In a vacuum cleaner, the fan serves to generate the negative pressure for sucking in dust.The fan of the domestic appliance can also be referred to as a fan or a fan. The motor of the fan of the domestic appliance is preferably a brushless direct current motor (BLDC motor) or an electrically commutated motor (EC motor) which drives a fan wheel, which can also be referred to as a fan wheel. These motors can be controlled in a simple manner on account of the electronic commutation, or the control can be set in a simple manner.The control unit of the fan can be integrated in the control device of the household appliance. Alternatively, the control unit of the fan can be designed as a separate unit from the control unit of the domestic appliance. In addition, the control unit of the fan is preferably designed to control the motor of the fan.According to the invention, the engine quality is determined in the method according to the invention. This determination may be made when the engine is first started or during operation of the engine.The quality of the engine, also referred to as engine quality, is a quantity that indicates the efficiency of the engine. In particular, the engine quality indicates how the engine converts the supplied electrical power into a mechanical power. Efficiency is affected by several factors, such as the dimension of the air gap, for example the gap between the stator and rotor of the motor, and other manufacturing factors. The engine quality can be given by numerical data. For example, a motor with an efficiency of 99% may be classified as a motor with a motor grade of 15. An engine with an efficiency of 85%, on the other hand, may be classified as an engine grade of 1, for example. Alternatively, the engine quality may also be evaluated by grades such as "good engine", "poor engine", etc. In this case, each classification can additionally be assigned a range of values of the efficiency of the engine.According to the invention, by controlling the fan depending on the detected engine quality, selection of fans with respect to an energy label can be limited to a minimum, and thus increased cost and waste of resources can be avoided. In addition, the dispersion in the delivery volume of the fan can be reduced and, as a result, the declaration of the fan can also be given correctly in a better energy label.The control of the fan is preferably adapted on the basis of the ascertained motor quality. In particular, deviations of the engine quality from a predefined engine quality are adapted by the control of the fan. In this way, tolerances of the motor, which cannot be avoided during the production of the motor, can be compensated for in the control.According to one specific embodiment, the ascertained engine quality is compared with an average value of the engine quality. The mean value of the engine quality is in particular the value which lies between the engine quality of an engine with minimum efficiency and with maximum efficiency. Thus, the average value preferably represents the average value between the worst and best motors.According to one specific embodiment, readjustment of the control is carried out only in the case of an engine quality which differs from the mean value. Readjustment of the control is understood in particular to mean a control by means of which a control and / or control stored in the control unit is changed. The control unit may store a regulation system which is designed for an engine with an engine quality with an average value. The readjustment can be effected, for example, by adapting a pulse width modulation (PWM) in the controller.The readjustment is preferably carried out only if the ascertained engine quality deviates downward from the mean value of the engine quality, that is to say if the engine has low efficiency.According to one specific embodiment, the ascertainment of the engine quality is carried out on the basis of the back-EMF determination.The back EMF denotes the voltage at the motor winding which is induced in the generator mode. The change in the rotational speed of the motor changes the sinusoidal waves detected at the back EMF. In particular, their frequency and amplitudes change, which can also be referred to as peaks. The higher the speed, the higher the frequency and amplitude of the back EMF sine wave. These peaks, representing the active phase and producing the change in magnetic field, are what actually drives the motor.According to one embodiment, the motor is accelerated to a defined rotational speed for ascertaining the motor quality, and the motor quality is subsequently determined via the height of the peak value of the back EMF.Since the peak reflects the actual drive of the motor, the height of the peak permits a statement about the motor quality. The correlation between the height of the peak and the motor quality is preferably stored in the control unit or an associated storage unit in the household appliance. The engine quality can thus be read out from these stored data.According to an alternative embodiment, the determination of the motor quality is carried out on the basis of an impulse response of the motor to a current / voltage impulse fed into the motor. In this embodiment, the assignment of impulse responses to an engine quality is preferably stored in the control unit or, if appropriate, in a memory unit assigned to the assigned control unit.According to a preferred embodiment, the stator and rotor are brought into a defined relative position before the current / voltage pulse is fed in.According to one embodiment, the determination of the engine quality is carried out when the extractor device is put into operation, preferably when the engine of the extractor device is first put into operation. This embodiment is applied in particular to a method in which the engine quality is determined on the basis of an impulse response. In this determination, the engine quality is determined in the stationary state of the engine.The embodiment of the method in which the determination of the motor quality is carried out on the basis of the back EMF determination can be carried out both during the initial startup and during the operation of the domestic appliance, in particular of the fan of the domestic appliance. In this type of determination, the engine quality is determined at a defined rotational speed of the engine.The defined rotational speed of the motor and the defined relative position are preferably stored in the control unit or an associated storage unit.According to a further aspect, the invention relates to a computer program product comprising instructions which, when the program is executed by the control unit, cause the control unit to execute the method according to the invention. The computer program product can also be referred to as a computer program or software. The household appliance preferably has a logic controller which can represent the control unit, can be part of the control unit or can be connected to the control unit. In particular, the computer program product represents microcontroller software. The microcontroller software runs on the logic controller of the household appliance.According to a further aspect, the invention relates to a household appliance having at least one fan with a motor and a control unit. The household appliance is characterized in that the household appliance is designed to carry out the method according to the invention. For this purpose, a sensor or another measuring unit as well as a processing unit for processing the sensor signals and / or the measured values can be provided in particular in the household appliance.According to one embodiment, the household appliance has at least one storage unit for storing the computer program product. The storage unit can be integrated in the control unit or connected to it for communication.Advantages and features which have been described with respect to the method according to the invention apply--insofar as applicable--also to the computer program product and the domestic appliance and vice versa.The invention will be explained again below with reference to the attached figures. The following are shown: FIG. 1 : shows a schematic flow diagram of a first embodiment of the method according to the invention; FIG. 2 : shows a schematic flow diagram of a second embodiment of the method according to the invention; and FIG. 3 : shows a schematic diagram of the variation of the delivery volume on account of different engine qualities.FIG. 1 schematically shows a first embodiment of the method according to the invention. In a first step, the engine is started and accelerated to a defined rotational speed. The back EMF is detected and the magnitude of the amplitudes, i.e. peaks, of the detected back EMF curve is determined. The quality of the motor is determined from the determined height. This can be done by means of a table or other correlation between the height of the back EMF peaks and the engine quality.The engine quality determined in this way is compared with an average value, in particular a stored average value, for engine quality. If the ascertained value matches the mean value, the method can be ended and the fan can be operated with the stored control, for example control stored at the factory. If the ascertained engine quality deviates from the average value downward, i.e. if the engine quality is poorer than the stored engine quality, the control is adapted. In particular, an adaptation of the PWM can take place. The fan is then operated with the adjusted controller. If the ascertained engine quality is greater than the mean value of the engine quality, i.e. the engine quality is better, the method can preferably be ended and the fan can be operated with the stored control. Alternatively, it is also possible that, in the case of a determined engine quality which is greater than the mean value, the control is adapted and the fan is subsequently operated with the adapted control.FIG. 2 schematically shows a second embodiment of the method according to the invention. The second embodiment differs from the first embodiment in the steps leading to the determination of the engine quality. The subsequent steps are the same as the steps of the first embodiment.In the second embodiment, the motor is started slowly and stopped at a defined relative position between the stator and the rotor of the motor. In this position, a current voltage pulse is applied to the motor. Then, an impulse response is obtained from the motor. The engine quality is determined from this impulse response. This determination can also be made on the basis of a table or other correlation between impulse response and engine quality.The present invention is not limited to the illustrated embodiments. For example, instead of a value of the engine quality, a classification such as "good engine", "poor engine" can also be determined. In this case, if the engine is rated poorly, the adjustment of the control can take place.FIG. 3 shows a diagram of the influence of the engine quality on the operating point of the fan. In this case, the rotational speed and the power consumed are plotted against one another. As can be seen from this diagram, with different engine qualities, a working point shift of the fan results. It follows from this that, due to different motor qualities, which are caused, for example, by production-related motor tolerances, delivery volume deviations of the fan occur. The diagram in FIG. 3 shows, by way of example, the values for a best-case and a worst-case engine.The present invention has a number of advantages.In particular, by means of the readjustment of the control according to the invention, delivery volume deviations can be compensated by production-related motor tolerances. Thus, a smaller dispersion in the delivery volume of the fan can be achieved. Due to this smaller variation, the fan and also the household appliance can be declared in a better energy label. Selection of fans and the resulting higher costs and waste of resources can be avoided by the targeted readjustment. Finally, by means of the present invention, important parameters for the user, such as, for example, delivery volume / pressure / noise, can be kept constant, in particular for different fans or household appliances.

Claims

Method for controlling a fan of a domestic appliance, wherein the fan comprises a motor and a control unit, characterised in that the quality of the motor is determined in the method and the control of the fan takes place as a function of the determined motor quality.Method according to Claim 1, wherein the ascertained engine quality is compared with an average value of the engine quality and readjustment is carried out only in the case of an engine quality which differs from the average value.Method according to either of Claims 1 and 2, wherein the determination of the engine quality is carried out on the basis of the back EMF determination.Method according to Claim 3, wherein the motor is accelerated to a defined rotational speed in order to determine the motor quality, and the motor quality is subsequently determined via the level of the peak value of the back EMF.Method according to Claim 1 or 2, wherein the determination of the motor quality is carried out on the basis of an impulse response of the motor to a current / voltage impulse fed into the motor.Method according to claim 5, wherein in the motor, prior to the application of the current / voltage pulse, the stator and rotor are brought into a defined relative position.Method according to one of Claims 1 to 6, wherein the determination of the motor quality is carried out when the domestic appliance is put into operation, preferably when the motor of the domestic appliance is first put into operation.A computer program product comprising instructions which, when the program is executed by the controller, cause the controller to perform the method of any one of claims 1 to 7.Household appliance having at least one fan with a motor and a control unit, characterised in that the household appliance is designed to carry out the method according to one of claims 1 to 7.Household appliance according to claim 9, wherein the household appliance has at least one storage unit for storing the computer program product.

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