Operating a household appliance with a BLDC drive motor

Abstract

The invention relates to a method (S0-S6) for operating a household appliance (1), in which, in order to start up a BLDC drive motor (5) of the household appliance (1), an actual rotational speed (ω) of a rotor (7) of the BLDC drive motor (5) is increased in a controlled manner from an idle state by means of a deterministic target control torque (Mref,det), and an actual angle (θ) and the actual rotational speed (ω) of the rotor (7) are determined by means of high-frequency injection, in the event that the actual rotational speed (ω) reaches or exceeds a first threshold rotational speed, the actual rotational speed (ω) is controlled to a target rotational speed (ωref), and in the event that the actual rotational speed (ω) reaches or exceeds a second threshold rotational speed, the actual angle (θ) and the actual rotational speed (ω) are determined from an EMF signal. The invention also relates to a household appliance (1) comprising a BLDC drive motor (5), wherein the household appliance (1) is designed to carry out the method (S0-S6). In particular, the invention can be advantageously used for starting up a BLDC drive motor, which drives a reciprocating compressor of a refrigeration circuit of a household refrigeration appliance, in particular a refrigerator.

Description

[0001] Operating a household appliance with a BLDC drive motor

[0002] The invention relates to a method for operating a household appliance, in which, in order to start up a BLDC drive motor of the household appliance, an actual speed of a rotor of the BLDC drive motor is increased from its rest state, and in the process, an actual angle and the actual speed are determined by means of high-frequency injection. The invention also relates to a household appliance with a BLDC drive motor, wherein the household appliance is configured to carry out the method. The invention is particularly advantageously applicable to starting up a BLDC drive motor that drives a reciprocating compressor of a refrigeration circuit of a household refrigeration appliance, in particular a refrigerator.

[0003] DE 10 2020 203 488 A1 discloses a household appliance and a method for operating a household appliance. The household appliance comprises a component and a controlled electric drive, which has a permanent-magnet three-phase synchronous motor, an actuator, in particular designed as a converter, for controlling the three-phase synchronous motor, and a field-oriented control system for controlling the actuator. The three-phase synchronous motor comprises a stator and a rotor rotatably mounted relative to the stator and is part of the component or is intended to drive this component, comprising the following method steps: during an operating phase of the electric drive, speed-controlled operation of the controlled electric drive by means of the field-oriented control system and as a function of an angular position of the rotor relative to the stator determined by means of the longitudinal and transverse currents and a mathematical model of the three-phase synchronous motor,and during a braking phase of the electric drive following the operating phase, - reducing the speed of the three-phase synchronous motor by speed-controlled operation of the controlled electric drive by means of field-oriented control and depending on an angular position of the rotor relative to the stator determined using the longitudinal and transverse currents and a mathematical model of the three-phase synchronous motor, until the speed reaches a predetermined limit speed, - superimposing a high-frequency voltage on a supply voltage generated by the actuator and intended to operate the three-phase synchronous motor, whereby phase currents and the longitudinal and transverse currents of the three-phase synchronous motor have corresponding high-frequency current components, - determining high-frequency current components of the longitudinal and transverse currents, - determining the angular position of the rotor relative to the stator depending on the high-frequency current components of the longitudinal and transverse currents,and - further reducing the speed of the three-phase synchronous motor by speed-controlled operation of the controlled electric drive by means of field-oriented control and depending on the angular position of the rotor relative to the stator determined by means of the high-frequency current components of the longitudinal and transverse currents.

[0004] DE 10 2020 203 489 A1 discloses a household appliance and a method for operating a household appliance. The household appliance comprises a component and a controlled electric drive, which has a permanent-magnet three-phase synchronous motor, an actuator, in particular designed as a converter, for controlling the three-phase synchronous motor, and a field-oriented control system for controlling the actuator. The three-phase synchronous motor comprises a stator and a rotor rotatably mounted with respect to the stator and is part of the component or is intended to drive this component, comprising the following method steps: during a start-up phase of the electric drive, - superimposing a high-frequency voltage on a supply voltage generated by the actuator and intended to operate the three-phase synchronous motor, whereby phase currents of the three-phase synchronous motor have corresponding high-frequency current components,- Determining the longitudinal and transverse currents assigned to the three-phase synchronous motor from the phase currents, which have high-frequency current components corresponding to the high-frequency voltage, - Determining the angular position of the rotor relative to the stator as a function of the high-frequency current components of the longitudinal and transverse currents, and - Increasing the speed of the three-phase synchronous motor by speed-controlled operation of the controlled electric drive by means of the field-oriented control and as a function of the angular position of the rotor relative to the stator determined by means of the high-frequency current components of the longitudinal and transverse currents until the three-phase synchronous motor reaches a predetermined limit speed, and during an operating phase following the start-up phase,Speed-controlled operation of the controlled electric drive using field-oriented control and depending on the angular position of the rotor relative to the stator, determined using the longitudinal and transverse currents and a mathematical model of the three-phase synchronous motor. For example, from DE 10 2016 210 443 A1 or DE 10 2017 213 069 A1, it is known to superimpose a high-frequency voltage on the supply voltage of a three-phase synchronous motor, which causes a corresponding, superimposed high-frequency component of the phase currents of the three-phase motor in order to determine the angular position of the rotor relative to the stator of the three-phase motor.

[0005] It is the object of the present invention to at least partially overcome the disadvantages of the prior art and, in particular, to provide a way to start up and shut down a BLDC drive motor of a reciprocating piston compressor of a household appliance in a way that is gentler on mechanical components of the household appliance and quieter, in particular to reduce knocking noise.

[0006] This object is achieved according to the features of the independent claims. Preferred embodiments can be found in particular in the dependent claims.

[0007] The object is achieved by a method for operating a household appliance, especially for starting up a BLDC drive motor of the household appliance, in which

[0008] - an actual speed, w, of a rotor of the BLDC drive motor is increased from its rest state by means of a deterministic target actuating torque, and an actual (position) angle, 0, and the actual speed w of the rotor are determined by means of high-frequency injection, HFI,

[0009] - if the actual speed w reaches or exceeds a specified first switching speed, the actual speed w is reduced to a target speed ω ref is regulated and

[0010] - if the actual speed w reaches or exceeds a specified second switching speed, the actual angle 0 and the actual speed w are determined using EMF.

[0011] This method has the advantage that, due to the precise knowledge of the position angle or angular position when using the HFI method, effective utilization of the actuating torque is possible even at low actual speeds w, because the torque can be reliably maintained. This allows the BLDC drive motor to be started up more gently for the mechanical components of the household appliance. The probability of knocking noise is also kept low. This takes advantage of the fact that the HFI method can determine the actual angle 0 and the actual speed w with sufficient accuracy even from speed w zero.

[0012] Switching from the HFI method to the EMF method at higher actual speeds has the advantage of avoiding the disadvantages of determining the actual angle and speed using high-frequency injection. For example, at higher actual speeds, computing power may not be sufficient to calculate the actual angle and speed promptly.

[0013] The household appliance can be a refrigeration appliance such as a refrigerator, a freezer, or a combination thereof. The household appliance can be a laundry appliance such as a washing machine, a tumble dryer, or a combination thereof (washer-dryer). However, the household appliance can also be a dishwasher, for example.

[0014] A "BLDC drive motor" is understood to mean, in particular, a brushless DC motor that is intended, i.e., arranged and configured, to drive another component of the household appliance. In particular, a rotor of the BLDC drive motor can serve as the drive shaft.

[0015] Ramp-up can also be referred to as starting or starting. It is a configuration in which the BLDC drive motor's actual speed w is zero when at rest, meaning the BLDC drive motor is ramped up from a standstill.

[0016] The "deterministic" target actuating torque is, in particular, a target actuating torque that is not generated by a closed-loop control system, but is calculated from measured or stored data and / or read from a data storage device, e.g., using at least one characteristic curve or tabular values. The deterministic target actuating torque can be parameterized, meaning that it is output depending on at least one parameter.

[0017] The controlled increase of the actual speed using the deterministic target torque particularly involves providing the deterministic target torque as an input variable or specification of a control system. This can, in particular, be a torque control system.

[0018] With high-frequency injection, a high-frequency voltage is superimposed on the supply voltage of the BLDC drive motor, which causes a corresponding, superimposed high-frequency component of the phase or motor currents of the BLDC drive motor to determine the actual angle of the rotor relative to the stator of the BLDC drive motor. The actual angle can also be referred to as the actual position angle or actual angular position. The actual speed of the rotor can be determined from the actual angle.

[0019] Regulating the actual speed to a target speed involves, in particular, outputting a target torque as a manipulated variable of a speed controller. Upon reaching a first speed threshold (the first "switching speed"), the system switches from control using the deterministic target torque to control in which the target torque is generated using a speed controller.

[0020] The fact that, if the actual speed reaches or exceeds a predetermined second switching speed, the actual angle and the actual speed are determined using EMF includes, in particular, that upon reaching a second speed threshold (the second "switching speed"), the method switches from determining the actual angle and the actual speed using high-frequency injection or a high-frequency injection method to determining the actual angle and the actual speed using EMF ("electromotive force") or an EMF method. EMF can also be referred to as BEMF ("back electromotive force").

[0021] The H Fl method and / or the ("electromotive force") method can be implemented in appropriate observers in a further training. The observers can, for example, be trained as Luenberger, Kalman, etc. observers or have Luenberger, Kalman, etc. observers.

[0022] One embodiment provides that the second switching speed is greater than the first switching speed, so that the system first switches to speed control and then switches to determining the actual angle and the actual speed using EMF. However, the method is not limited to this; the second switching speed can also be lower than the first switching speed. Another embodiment provides that the first switching speed corresponds to the second switching speed.

[0023] A value that corresponds to the physical meaning of a torque can be used as the target actuating torque. Alternatively, at least one value that analogously maps the physical meaning of a torque in relation to the motor, e.g., target currents in a d / q system, can be used as the target actuating torque. Consequently, a torque value or, equivalently, the target currents in the d / q system can be output as an example of a deterministic target actuating torque.

[0024] It is an embodiment that by means of a vector control from a target actuating torque and the actual angle, control signals for energizing coils of the BLDC drive motor are generated, whereby

[0025] - when the actual speed has not yet reached or exceeded the first switching speed, the target torque supplied to the vector control is the deterministic target torque and

[0026] - when the actual speed w reaches or exceeds the first switching speed, the setpoint actuating torque supplied to the vector control is a manipulated variable of a speed control whose reference variable corresponds to the setpoint speed and whose feedback variable corresponds to the actual speed.

[0027] Field-Oriented Control (FOC) can include space vector modulation (SVPWM). Vector control uses, in particular, setpoint currents in the d / q system, specifically a setpoint I d -current and a target I qCurrent. These target currents in the d / q system can be calculated from the target actuating torque and can correspond to the target actuating torque with high accuracy. The target currents in the d / q system can therefore be viewed as representatives of the target actuating torque in the d / q system. A further development is that the vector control outputs measured or internally calculated variables as measured variables for observers, e.g., measured motor currents and / or voltages and / or currents in a rotor-related α / β system.

[0028] One embodiment involves generating the deterministic target actuating torque using a signal generator. The signal generator generates an output signal corresponding to the deterministic target actuating torque based on input values, e.g., values ​​calculated using a formula or retrieved from a data storage device. The signal generator is not a closed-loop control system and can therefore also be referred to as a "closed-loop control" signal generator.

[0029] One embodiment is that the deterministic target torque is a constant target torque. This is advantageously particularly easy to implement.

[0030] One embodiment is that the deterministic target actuating torque is a temporal progression of the target actuating torque or has more than two consecutive, different values. This provides the advantage that the start-up can be carried out particularly smoothly.

[0031] In one embodiment, the deterministic target actuating torque is dependent on at least one pressure present in a reciprocating piston compressor of the household appliance driven by the BLDC drive motor, or a variable derived therefrom, e.g., a pressure ratio. This advantageously allows the target actuating torque to be specifically adapted to the pressure(s) in the reciprocating piston compressor and thus to the expected load pressures. This, in turn, enables a particularly smooth start-up. A further advantage of the method when used with a reciprocating piston compressor is that, when starting up, "sticking" during the first compression is avoided by specifying the deterministic target actuating torque, even under high load conditions.

[0032] It is a design that the vector control logic is preceded by an MTPA ("Maximum Torque per Ampere") logic, which converts the target actuating torque into a target I d-current and into a target I q -current and can be passed on as input variables, for example, to the vector control logic. This is advantageous for operating the BLDC motor particularly effectively based on the target actuating torque. For the same purpose, it is an improvement to integrate field weakening logic into the MTPA logic.

[0033] One embodiment involves driving, or being able to drive, a reciprocating piston compressor using the BLDC drive motor. This method is particularly advantageous for this purpose because, in this case, the probability of mechanical stress on the components of the household appliance during startup, resulting in noise, is particularly high.

[0034] It is a further development that the reciprocating compressor is a component of a refrigeration circuit. It is then a configuration that the household appliance is a refrigeration appliance, e.g., a refrigerator, a freezer, or a combination thereof.

[0035] It is a further development that the reciprocating compressor is a component of a heat pump. In this case, the household appliance can be, for example, a laundry appliance such as a washing machine, a tumble dryer, or a combination of both (washer-dryer). However, the household appliance can also be a dishwasher.

[0036] It is a further development that a laundry drum of a laundry treatment device is driven or can be driven by means of the BLDC drive motor.

[0037] The problem is also solved by a household appliance with a BLDC drive motor, wherein the household appliance is configured to carry out the method as described above. The household appliance can be designed analogously to the method, and vice versa, and has the same advantages.

[0038] For example, the household appliance can be a refrigeration appliance in which a compressor, in particular a reciprocating compressor, of a refrigeration circuit can be driven by means of the BLDC drive motor.

[0039] It is a further development that the BLDC drive motor can be controlled by means of an inverter circuit and the inverter circuit is set up to carry out the method.

[0040] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following schematic description of an embodiment, which is explained in more detail in conjunction with the drawings. Fig. 1 shows a sectional side view of a household appliance in the form of a refrigerator;

[0041] Fig.2 shows a possible functional structure of a motor control for driving a drive motor of the household appliance from Fig.1;

[0042] Fig.3 shows in more detail a possible functional structure of a vector control of the motor control from Fig.2;

[0043] Fig.4 shows a possible sequence of a method for starting the drive motor.

[0044] Fig. 1 shows a sectional side view of a household appliance in the form of a refrigerator 1. The refrigerator 1 has a cooling chamber 2, the front loading opening of which can be closed by a door 3. The refrigerator 1 is controlled by a control device 4. In a further development, the control device 4 can control a BLDC drive motor 5 of a compressor 6 of a refrigeration circuit. The compressor 6 is designed here as a reciprocating piston compressor. The BLDC drive motor 5 has a rotor 7 serving as a drive shaft and can be controlled by a motor controller 8, which generates control signals for energizing coils of the BLDC drive motor 5. The motor controller 8 can be a component of the BLDC drive motor 5, e.g.be integrated in hardware and / or software into a converter circuit 9 of the BLDC drive motor 5, in particular in a controller 10 of the converter circuit 9, see Fig. 2. Alternatively, the converter circuit 9 or the entire motor control 8 can also be integrated into the control device 4 of the refrigerator 1.

[0045] Fig.2 shows a possible functional structure of the engine control 8 using various functional blocks.

[0046] One of the function blocks is a speed control 11 , which uses a target speed Wref and an actual speed w of the rotor 7 as a control variable to generate a target actuating torque M ref, stell calculated.

[0047] Another of the function blocks is a signal generator 12, which - independent of the actual speed w - generates a deterministic target actuating torque M ref,det This deterministic target torque M ref,detcan be constant or can be a time-dependent characteristic. In particular, the deterministic target torque M ref,det be parameterized.

[0048] An MTPA logic 13, which may also include a field weakening logic, calculates on the basis of an entered target actuating torque M ref an equivalent pair of target I d -Current I d,ref and target I q -Current l q , ref in the d / q system and transfers these values ​​to a vector control 14. The target actuating torque M entered into the MTPA logic 13 ref is, as schematically indicated by the switch symbol, either the target actuating torque M output by the speed control 11 ref, stell or the deterministic target actuating torque M output by the signal generator 12 ref,det .

[0049] The vector control 14 calculates from the target I d -Current I d,ref , the target I q -Current l q ,ref and from an actual angle 0 of the rotor 7, the control signals for energizing the coils of the BLDC drive motor 5.

[0050] The motor control 8 further comprises an observer 15, e.g., a Luenberger observer, which receives input or measured variables B from the vector control 14 and uses them to calculate or estimate the actual angle θ and the actual speed w of the rotor 7. The actual angle θ is transferred to the vector control 14, and the actual speed w is transferred to the speed control 11.

[0051] The observer 15 here comprises an HFI (high-frequency injection) observer 16, which determines, in particular estimates, the actual angle 0 and the actual speed w from measured variables B in the form of motor currents that have a high-frequency component generated by high-frequency injection. The observer 15 further comprises an EMF observer 17, which determines, in particular estimates, the actual angle 0 and the actual speed w from measured variables B in the form of transformed measured motor currents and motor voltages calculated in the vector control 14 by EMF.

[0052] Fig.3 shows a possible more detailed design of the vector control 14 and the observers 16 and 17.

[0053] First, a difference between the target I supplied by the MTPA logic 13 d -Current I d,ref and an actual I d -Current I d formed, as well as a difference from target I q -Current I q,ref and actual I q -Current Iq The differences are fed to the respective controllers 19, e.g., PI controllers. The controllers 19 can also be referred to as current controllers. The controllers 19 output a voltage V d or V q which are passed to an inverse Park transformation 20.

[0054] The inverse Park transformation 20 calculates from the voltages V d and V q and the actual angle 0 voltages V α and V β in the α / β system and transfers them to a space vector modulation 21 (SVPWM). The space vector modulation 21 generates control signals GS, e.g., gate signals for transistors, for a four-quadrant controller 22, which no longer needs to be part of the vector controller 14. The four-quadrant controller 22 energizes the BLDC drive motor 5 according to the control signals GS.

[0055] Furthermore, the vector control 14 comprises a Clarke transformation 23, which converts the measured motor currents la , l b , l c in streams l a , I β in the α / β system, which in turn is converted into the actual I by means of a Park transformation 24 with knowledge of the actual angle 0 d -Current I d and the actual I q -Current l q Blocks 23 and 24 can also be collectively referred to as the Clarke-Park transformation. The actual I d -Current I d and the actual I q - Electricity l q are used to calculate the difference with the target I d -Current I d,ref or the target I q -Current I q .ref returned.

[0056] The HFI observer 16 receives from the vector control 14 as measured variables B the motor currents l which are still subjected to high frequency a , l b , l cand estimates the actual angle 0 and the actual speed w of the rotor 7. The HFI observer 16 can, in a further development, include a Luenberger, Kalman, etc. observer.

[0057] The EMF observer 17 receives from the vector control 14 as measured variables B the currents l a , I β in the α / β system and the voltages V a , V β In the α / β system, the actual angle 0 and the actual speed w of the rotor 7 are estimated from this. The EMF observer 17 can be trained as a Luenberger, Kalman, etc. observer.

[0058] Fig.4 shows a possible embodiment of how the motor control 8 can increase or decrease the speed.

[0059] Starting of the BLDC drive motor 5: It is assumed that the BLDC drive motor 5 is in its rest state in a step S0, in which its actual speed w is zero, e.g. because it is not energized.

[0060] In a step S1, H Fl signals are assigned to the motor currents Motor currents l a , l b , l c impressed and the motor currents l a , l b , l c applied to the BLDC drive motor 5. The actual angle 0 and the actual speed w of the rotor 7 are determined by means of the H Fl observer 16, particularly cyclically, e.g., with a period TA of approximately 250 ps. It is advantageous that w = 0 can also be detected using the high-frequency injection method.

[0061] In step S2, the deterministic target actuating torque M ref .det, meaning that M ref = M ref,det applies, and output to the MTPA logic 13. This calculates the target I d -Current I d,ref and the target I q -Current l q , refcalculated and transferred to the vector control 14. The vector control 14 generates the control signals GS from this and from the actual angle 0 estimated by the HFI observer 16, as already described above, and also outputs the measured variables B for the HFI observer 16.

[0062] In step S3, a check is made to determine whether the actual speed w determined by the H Fl observer 16 has reached or exceeded a first threshold value, namely the first switching speed. If not ("N"), the system returns to step S1.

[0063] In steps S1 to S3, the speed control 11 is not used.

[0064] If yes ("Y"), the system proceeds to step S4, in which the deterministic target actuating torque M generated by the signal generator 14 is no longer used. ref,det is output to the MTPA logic 15, but the target actuating torque M calculated by the speed control 11 ref, stell , ie, that M ref = M ref, stell applies.

[0065] Analogous to step S2, the MTPA logic 13 calculates from M ref = M ref, stell the target I d -CurrentI d,ref and the target I q -Current l q , ref transfers them to the vector control 14, which generates the control signals GS from these and from the actual angle θ estimated by the HFI observer 16 and outputs the measured variables B for the HFI observer 16. In step S5, a check is made to determine whether the actual speed ω determined by the HFI observer 16 has reached or exceeded a second threshold value, namely the second switching speed. If not ("N"), the system returns to step S4. If this is the case ("Y"), however, the system proceeds to step S6.

[0066] In step S7, the actual angle 0 and the actual speed w are now determined using the EMF observer 17, but otherwise the procedure is analogous to step S4.

[0067] Of course, the present invention is not limited to the embodiment shown.

[0068] Thus, in the embodiment described in Fig. 4, it is assumed that the second switching speed is greater than the first switching speed. However, alternatively, the first switching speed may be greater than the second switching speed, or the two switching speeds may be equal.

[0069] In addition, the MTPA logic 13 can also be omitted. In this case, either the target I d -Current I d,ref and the target I q -Current l q , ref using other calculation rules from the target actuating torque M ref calculated or converted in the vector control 14 or output directly from the speed controller 11 and the signal generator 12.

[0070] In addition, the actual angle 0 and / or the actual speed ω can be determined by means of a sensor instead of an observer 15, e.g. by means of at least one Hall sensor installed in the BLDC drive motor 5.

[0071] In general, "a", "an", etc., can be understood as a singular or a plural, in particular in the sense of "at least one" or "one or more", etc., as long as this is not explicitly excluded, e.g. by the expression "exactly one", etc.

[0072] A numerical specification can also include the exact number specified as well as a usual tolerance range, as long as this is not explicitly excluded.

[0073] 1 refrigerator

[0074] 2 cold storage rooms

[0075] 3 Door

[0076] 4 Control device

[0077] 5 BLDC drive motor

[0078] 6 compressors

[0079] 7 Rotor

[0080] 8 Engine control

[0081] 9 Inverter circuit

[0082] 10 controllers

[0083] 11 Speed ​​control

[0084] 12 signal generators

[0085] 13 MTPA logic

[0086] 14 Vector control

[0087] 15 observers

[0088] 16 high-frequency injection observers

[0089] 17 EMK observers

[0090] 19 PI controllers

[0091] 20 Inverse Park transformation 21 Space vector modulation 22 Four-quadrant controller 23 Clarke transformation 24 Park transformation B Measured variable GS Control signals l a , l b , l c Motor currents I d Actual I d -Current I q Actual I q -Current I d, ref Target I d -Current I q,ref Target I q -Electricity

[0092] M ref Target actuating torque M ref,det Deterministic target actuating torque

[0093] M ref, stell Target actuating torque

[0094] S0-S6 procedural steps

[0095] V a Voltage in the α / β system V β Tension in the α / β system

[0096] V d Tension in the d / q system

[0097] V q Voltage in the d / q system ω Actual speed ω ref Target speed θ Actual angle

Claims

Patent claims 1. Method (S0-S6) for operating a household appliance (1), in which for starting up a BLDC drive motor (5) of the household appliance (1) - an actual speed (w) of a rotor (7) of the BLDC drive motor (5) from its rest state by means of a deterministic target actuating torque (M ref,det ) is increased in a controlled manner and an actual angle (0) and the actual speed (w) of the rotor (7) are determined by means of high-frequency injection, - if the actual speed (w) reaches or exceeds a first switching speed, the actual speed (w) is reduced to a target speed ( ω ref ) and - if the actual speed (w) reaches or exceeds a second switching speed, the actual angle (0) and the actual speed (w) are determined from an EMF signal.

2. Method (S0-S6) according to claim 1, wherein the second switching speed is greater than the first switching speed.

3. Method (S0-S6) according to one of the preceding claims, in which a vector control (12) is used to determine a desired actuating torque (M ref ) and the actual angle (0) control signals for energizing coils of the BLDC drive motor (5) are generated, wherein - when the actual speed (w) has not yet reached or exceeded the first switching speed, the target actuating torque (M ref ) the deterministic target actuating torque (M ref,det ) and - when the actual speed (w) reaches or exceeds the first switching speed, the target actuating torque (M ref ) a control variable ( M ref, stell ) of a speed control (11) whose reference variable corresponds to the target speed (Wref) and whose feedback variable corresponds to the actual speed (w).

4. Method (S0-S6) according to one of the preceding claims, in which the deterministic target actuating torque (M ref,det ) is generated by means of a signal generator (14).

5. Method (S0-S6) according to one of the preceding claims, in which the deterministic target actuating torque (M ref,det ) is a constant target actuating torque.

6. Method (S0-S6) according to one of claims 1 to 4, wherein the deterministic target actuating torque (M ref,det ) is a temporal progression of the target actuating torque.

7. Method (S0-S6) according to one of the preceding claims, in which the deterministic target actuating torque (M ref,det ) depends on at least one pressure present in a reciprocating piston compressor of the household appliance (1) driven by the BLDC drive motor (5) or a variable derived therefrom.

8. Method (S0-S6) according to one of claims 3 to 7, in which the vector control logic (12) is preceded by an MTPA logic (15) which determines the desired actuating torque (M ref ) into a target I d -Current (I d,ref ) and into a target I q -Current (l q , ref ) and passed on as input variables to the vector control logic (16).

9. Method (S0-S6) according to one of the preceding claims, wherein in the idle state of the BLDC drive motor (5) its actual speed (w) is zero.

10. Household appliance (1) with a BLDC drive motor (5), wherein the household appliance (1) is configured to carry out the method (S0-S6) according to one of the preceding claims.

11. Household appliance (1) according to claim 10, wherein a reciprocating piston compressor (6) can be driven by means of the BLDC drive motor (5).

12. Household appliance (1) according to one of claims 10 to 11, wherein the household appliance (1) is a refrigeration appliance, in particular a refrigerator.

Images