DE102019110045A1 - Method for operating a drive system with a single-phase synchronous motor - Google Patents

Abstract

The invention relates to a method for operating a drive system (1-4) with a single-phase synchronous motor (1) with at least the following steps: • Operating (100) the single-phase synchronous motor (1) with a first electrical frequency (Frequency) of a reference voltage ( Uref), • Interrupting (200) the operation of the single-phase synchronous motor (1) for a measuring period (T_mess), the measuring period (T_mess) including a zero crossing of a motor current (I_motor), • within the measuring period (T_mess) at the time of the zero crossing of the motor current (I_motor), recording (300) an induced voltage (Bemf_Sample), • comparing (400) the recorded induced voltage (Bemf_Sample) with a setpoint value of the induced voltage (Bemf_ref) and • re-operating (800) the single-phase synchronous motor ( 1) with a second electrical frequency (Frequency) of the reference voltage (Uref) depending on the result of the comparison (400).

Description

The invention relates to a method for operating a drive system with a single-phase synchronous motor according to claim 1, a drive system for carrying out such a method according to claim 13, a household appliance component with such a drive system according to claim 15 and a household appliance with such a household appliance component according to the Claim 16.

The known electric motors also include synchronous motors, which can be operated single-phase with alternating current or multi-phase with three-phase current. In any case, a constantly magnetized rotor is used, which can also be referred to as a rotor. Permanent magnets or an external electromagnetic excitation can be used for this. The term synchronous motor results from the fact that the rotor is driven synchronously by a moving alternating magnetic field or rotating field in the stator, also called the stator. In operation, the synchronous motor thus has a movement that is synchronous with the alternating voltage, the speed of which is linked to the frequency of the alternating voltage via the torque-generating number of pole pairs of the synchronous motor.

Multi-strand permanent magnet synchronous motors are usually operated via a frequency converter, which enables controlled operation in that the direction of rotation, speed and torque of the synchronous motor can be specified via the frequency and amplitude of the AC output voltage of the frequency converter. This can change the rotational behavior of the synchronous motor e.g. during start-up and depending on the load to be driven.

The disadvantage here is that such frequency converters cause additional costs and can require additional installation space. In addition to the frequency converter itself, these costs can arise from additional electronics in the drive system. It is precisely these costs that are important for various simple applications such as Simple pumps, such as lye pumps in washing machines, are highly undesirable because the options for regulating or controlling the synchronous motor created by the frequency converter are not required for these applications and the additional costs of the frequency converter are therefore not worthwhile. Such simple applications in e.g. Lye pumps in washing machines include pumping the lye out of the washroom or flooding. In both cases, regulated operation - regulated because information about the rotor position is available to the frequency converter - the drain pump is not required.

As a cost-effective alternative to synchronous motors operated by frequency converters, it is ideal for simple applications such as It is known for drain pumps in washing machines to use unregulated single-phase synchronous motors as drives for the drain pump. Here, permanent magnet single-phase synchronous motors are usually used, so that there is no need for electrical contact from the stator to the rotor by means of slip rings or brushes.

As already mentioned in general, it is also advantageous in the case of permanent-magnet single-phase synchronous motors that they execute a movement that is synchronous to the alternating voltage during operation, the speed of which is linked to the frequency of the alternating voltage via the number of pole pairs. This means that it is very easy to operate a permanently excited single-phase synchronous motor with the frequency of the alternating voltage of the network, and cost-intensive controls and frequency converters can be dispensed with. This is particularly useful for simple "unregulated" applications with constant speed, such as for drain pumps in washing machines.

However, it is disadvantageous that such permanent-magnet single-phase synchronous motors are usually designed for the highest load point or for the highest operating point, and their efficiency is therefore lower and therefore not optimal for all other loads. In other words, their efficiency is not constant for the load range.

Another disadvantage is that when using an unregulated permanent magnet single-phase synchronous motor, no information about the operating state of the motor, such as about load fluctuations in a drain pump in the form of slurping, i.e. conveying an air-water mixture. If this state cannot be recognized, the washing machine cannot react to it either.

Another disadvantage is that the speed of a permanently excited single-phase synchronous motor is not variable and depends on the mains frequency prevailing in the respective country of use and the number of pole pairs of the machine. The permanent-magnet single-phase synchronous motor can thus only be operated at a single electrical speed, which in the stationary state corresponds to the mechanical speed of the single-phase synchronous motor with a number of pole pairs of one. This could be 60 Hz in the USA or 50 Hz in Europe. Therefore, different interpretations of the are for different countries or network frequencies to make and use permanent magnet single-phase synchronous motor, which means additional work for the manufacturer and may require separate approvals.

Another disadvantage is that if the position of the rotor is to be recorded relative to the stator, an additional so-called rotor position sensor must be used for this purpose. This leads to additional costs for the rotor position sensor and also requires additional installation space.

It is also disadvantageous that if a parking magnet is used to align the starting position of the rotor relative to the stator, this also leads to additional costs and requires additional installation space.

The invention thus poses the problem of providing a method for operating a drive system with a single-phase synchronous motor of the type described at the beginning, so that the possibilities for operating the drive system can be expanded. In particular, it should be possible to improve the efficiency of the single-phase synchronous motor during operation. Additionally or alternatively, the mechanical speed of the single-phase synchronous motor should be able to be influenced during operation. This should be done as simply, inexpensively and / or reliably as possible. Furthermore, it should preferably be possible to dispense with a parking magnet and / or a rotor position sensor. The drive system should also preferably be able to be used for the voltage supplies in different countries. At least one alternative to known methods for operating a drive system with a single-phase synchronous motor is to be created.

According to the invention, this problem is solved by a method with the features of claim 1, by a drive system with the features of claim 13, by a household appliance component with the features of claim 15 and by a household appliance with the features of claim 16. Advantageous refinements and developments of the invention emerge from the following subclaims.

• • Betreiben des Einphasen-Synchronmotors mit einer ersten elektrischen Frequenz einer Referenzspannung,
• • Unterbrechen des Betriebs des Einphasen-Synchronmotors für einen Messzeitraum, wobei der Messzeitraum einen Nulldurchgang eines Motorstroms einschließt,
• • innerhalb des Messzeitraums zum Zeitpunkt des Nulldurchgangs des Motorstroms, Erfassen einer induzierten Spannung,
• • Vergleichen der erfassten induzierten Spannung mit einem Sollwert der induzierten Spannung und
• • erneutes Betreiben des Einphasen-Synchronmotors mit einer zweiten elektrischen Frequenz der Referenzspannung in Abhängigkeit des Ergebnisses des Vergleichens.

The present invention thus relates to a method for operating a drive system with a single-phase synchronous motor with at least the following steps:

• • Operation of the single-phase synchronous motor with a first electrical frequency of a reference voltage,
• • Interrupting the operation of the single-phase synchronous motor for a measuring period, the measuring period including a zero crossing of a motor current,
• • within the measurement period at the time of the zero crossing of the motor current, acquisition of an induced voltage,
• • Compare the detected induced voltage with a setpoint value for the induced voltage and
• • renewed operation of the single-phase synchronous motor with a second electrical frequency of the reference voltage depending on the result of the comparison.

The present invention is based on the knowledge that when switching off the PWM in the zero crossing, i.e. when the current is equal to zero, and after a short discharge time of the residual energy in the inductance, the voltage measured at the motor corresponds exactly to the value of the electromotive force Emk. The detected, applied voltage as induced voltage can now be compared with a nominal value of the induced voltage and conclusions can be drawn from the result of the comparison about the phase position between the motor current and the induced voltage. Based on this, the further operation of the single-phase synchronous motor of the drive system can take place, as will be described in more detail below. This makes it possible to operate the single-phase synchronous motor with extended options. The method according to the invention can preferably be carried out continuously and repeatedly.

As already mentioned, it should be noted that the nominal value of the induced voltage determines the phase or the phase position between the motor current and the induced voltage. The operating point of the single-phase synchronous motor can thus be specified by specifying the setpoint value for the induced voltage.

According to one aspect of the present invention, for the case that, according to the comparison, the detected induced voltage corresponds to the setpoint value of the induced voltage, the second electrical frequency of the reference voltage corresponds to the first electrical frequency of the reference voltage. In this case, the single-phase synchronous motor is already operated according to a specification which is expressed by the predetermined setpoint value of the induced voltage, so that the operation can continue unchanged.

• • Verändern der zweiten elektrischen Frequenz der Referenzspannung gegenüber der ersten elektrischen Frequenz der Referenzspannung.

According to a further aspect of the present invention, in the event that, according to the comparison, the detected induced voltage does not correspond to the nominal value of the induced voltage, at least one further step takes place:

• • Changing the second electrical frequency of the reference voltage compared to the first electrical frequency of the reference voltage.

In this case, the single-phase synchronous motor is operated in a manner deviating from the specification, which is expressed by the predetermined setpoint value of the induced voltage, so that the operation can be changed. This can take place as a function of the discrepancy between the detected induced voltage and the nominal value of the induced voltage, as will be described in more detail below.

According to a further aspect of the present invention, in the event that the zero crossing of the motor current takes place from positive to negative and that the difference between the detected induced voltage and the setpoint value of the induced voltage is positive, changing the second electrical frequency of the reference voltage compared to the first electrical frequency of the reference voltage to reduce the first electrical frequency of the reference voltage. From this constellation of the direction of the zero crossing of the motor current and the sign of the difference between the detected induced voltage and the nominal value of the induced voltage, it can be concluded that the detected induced voltage lags behind the motor current whose electrical frequency of the reference voltage is reduced, which, indirectly, leads to a reduction in the difference between the detected induced voltage and the nominal value of the induced voltage. This can be determined in the subsequent execution of the method according to the invention, so that these steps can be repeated until the difference between the detected induced voltage and the nominal value of the induced voltage is balanced and the mechanical frequency, i.e. the mechanical speed of the single-phase synchronous motor corresponds to the electrical frequency of the reference voltage and the specified phase between Emk and current is reached.

According to a further aspect of the present invention, if the zero crossing of the motor current takes place from positive to negative and the difference between the detected induced voltage and the setpoint value of the induced voltage is negative, changing the second electrical frequency of the reference voltage compared to the first electrical frequency of the reference voltage to increase the first electrical frequency of the reference voltage. From this constellation of the direction of the zero crossing of the motor current and the sign of the difference between the detected induced voltage and the nominal value of the induced voltage, it can be concluded that the detected induced voltage leads the motor current.

In response to this, the electrical frequency of the reference voltage is increased for the further operation of the single-phase synchronous motor, which, indirectly, leads to a reduction in the difference between the detected induced voltage and the setpoint value of the induced voltage. This can be determined in the subsequent execution of the method according to the invention, so that these steps can be repeated until the difference between the detected induced voltage and the nominal value of the induced voltage is balanced and the mechanical frequency, i.e. the mechanical speed of the single-phase synchronous motor corresponds to the electrical frequency of the reference voltage and the specified phase between Emk and current is reached.

According to a further aspect of the present invention, in the event that the zero crossing of the motor current takes place from negative to positive and that the difference between the detected induced voltage and the setpoint value of the induced voltage is positive, changing the second electrical frequency of the reference voltage compared to the first electrical frequency of the reference voltage to increase the first electrical frequency of the reference voltage. Also in this constellation of the direction of the zero crossing of the motor current and the sign of the difference between the detected induced voltage and the setpoint value of the induced voltage, the detected induced voltage leads the motor current. As previously described, this is responded to by increasing the electrical frequency of the reference voltage.

According to a further aspect of the present invention, in the event that the zero crossing of the motor current takes place from negative to positive and that the difference between the detected induced voltage and the target value of the induced voltage is negative, changing the second electrical frequency of the reference voltage compared to the first electrical frequency of the reference voltage to reduce the first electrical frequency of the reference voltage. Also in this constellation of the direction of the zero crossing of the motor current and the sign of the difference between the detected induced voltage and the setpoint value of the induced voltage, the detected induced voltage lags behind the motor current. As previously described, this is responded to by reducing the electrical frequency of the reference voltage.

According to a further aspect of the present invention, the desired value of the induced voltage is equal to zero. As mentioned above, the setpoint of the induced voltage determines the phase or the phase position between the motor current and the induced voltage, so that the operating point of the single-phase synchronous motor can be specified by specifying the setpoint of the induced voltage. If the nominal value of the induced voltage is now given equal to zero, this should ensure that the motor current and the induced voltage are in phase with one another. This leads to an operation of the single-phase synchronous motor with optimal efficiency, so that according to the invention optimal operation can be achieved in a simple manner. According to the invention, the operating point can be changed by specifying the setpoint value for the induced voltage.

• • Vergleichen der zweiten elektrischen Frequenz der Referenzspannung mit einem Sollwert der elektrischen Drehfrequenz,

wobei das erneute Betreiben des Einphasen-Synchronmotors ferner mit einer zweiten elektrischen Amplitude der Referenzspannung in Abhängigkeit des Ergebnisses des Vergleichens erfolgt.According to a further aspect of the present invention, the single-phase synchronous motor is operated with the first electrical frequency of the reference voltage, furthermore with a first electrical amplitude of the reference voltage, and the method furthermore has at least the further step:

• • Compare the second electrical frequency of the reference voltage with a setpoint value of the electrical rotary frequency,

wherein the renewed operation of the single-phase synchronous motor also takes place with a second electrical amplitude of the reference voltage as a function of the result of the comparison.

This aspect of the present invention is based on the knowledge that a change in the speed of the single-phase synchronous motor can take place indirectly via a change in the amplitude of the reference voltage, since the change in the amplitude of the reference voltage as the motor voltage affects the phase shift between the motor current and the induced voltage affects. This leads to a change in the specified phase between Emk and motor current, which leads to a change in the actual electrical frequency of the single-phase synchronous motor, as described above, which results in a change in the mechanical frequency, i.e. the mechanical speed of the single-phase synchronous motor. Thus, this possibility for changing the operation of the single-phase synchronous motor can also be made available in a simple manner.

According to a further aspect of the present invention, in the event that, according to the comparison, the second electrical frequency of the reference voltage corresponds to the setpoint value of the electrical rotational frequency, the second electrical amplitude of the reference voltage corresponds to the first electrical amplitude of the reference voltage. In this case, the single-phase synchronous motor is already operated according to a specification which is expressed by the setpoint value of the electrical rotational frequency, so that the operation can continue unchanged.

• • Verändern der zweiten elektrischen Amplitude der Referenzspannung gegenüber der ersten elektrischen Amplitude der Referenzspannung.

According to a further aspect of the present invention, in the event that, according to the comparison, the second electrical frequency of the reference voltage does not correspond to the nominal value of the electrical rotational frequency, at least the further step takes place:

• • Changing the second electrical amplitude of the reference voltage compared to the first electrical amplitude of the reference voltage.

In this case, the single-phase synchronous motor is operated differently from the specification, which is expressed by the setpoint of the electrical rotational frequency, so that the operation can be changed. This can take place as a function of the deviation of the second electrical frequency of the reference voltage and the setpoint value of the electrical rotary frequency.

In order to increase the electrical speed of the single-phase synchronous motor, the amplitude of the motor voltage can be increased. Due to the electrical properties of the single-phase synchronous motor, this leads to the detected induced voltage running ahead of the motor current, which, as described above, leads to an increase in the electrical frequency in order to compensate for the phase difference between the detected induced voltage and motor current. This can be done by means of the phase control described above, e.g. take place by means of a phase-locked loop (English also phase-locked loop - PLL). If this is achieved, the detected induced voltage and the motor current are again in the specified phase with respect to one another and the single-phase synchronous motor is again operated in a steady state, but at a higher speed than before. To reduce the electrical speed of the single-phase synchronous motor, the amplitude of the motor voltage can be reduced accordingly.

According to a further aspect of the present invention, the target value of the electrical rotational frequency corresponds to a predetermined mechanical rotational speed of the single-phase synchronous motor. In this way, a mechanical speed of the single-phase synchronous motor can be specified. Different setpoint values for the electrical rotational frequencies can also be specified in order to be able to vary the mechanical speed of the single-phase synchronous motor accordingly. This can increase the possibilities of operating the single-phase synchronous motor.

With regard to the previously described method according to the invention with its various aspects, it can also be noted that this makes it possible to create additional options for operating a single-phase synchronous motor in a simple manner. In particular, the operation of the single-phase synchronous motor can be influenced very easily, precisely and / or in a variety of ways. In particular, a change in the mechanical frequency, i. the mechanical speed, the single-phase synchronous motor can be made easily and / or flexibly. Optimal efficiency can also be achieved for different mechanical or electrical speeds.

It is also advantageous that this makes it possible to operate the same single-phase synchronous motor or the same drive system at different mains voltages with different frequencies, so that different country versions of the single-phase synchronous motor or drive system can be dispensed with.

It is also advantageous that the electronics required to carry out the method according to the invention are implemented comparatively simply and e.g. can be integrated as an additional functional unit of a control unit of the drive system. This can simplify the implementation and keep costs and installation space for this low. Due to its simplicity, the method according to the invention can also be implemented in a comparatively short computing time, so that an additional electronic computer unit of the control unit of the drive system can be dispensed with.

It is also advantageous that the method according to the invention can be implemented and operated independently of the motor parameters of the single-phase synchronous motor, since only the previously described measured variables need to be recorded and taken into account, which are independent of the knowledge of the motor parameters.

A position sensor and a parking magnet can advantageously also be dispensed with, which can keep the effort and costs of the drive system according to the invention low.

The present invention also relates to a drive system with a single-phase synchronous motor with a switching unit which is designed to operate the single-phase synchronous motor with a first and a second electrical frequency of a reference voltage, preferably also with a first and a second electrical amplitude of the reference voltage, to operate, wherein the switching unit is further designed to interrupt the operation of the single-phase synchronous motor for a measurement period, the measurement period including a zero crossing of a motor current, the single-phase synchronous motor being designed to generate an induced voltage within the measurement period at the time of the zero crossing Detect motor current, wherein the drive system, preferably a control unit of the drive system, is designed to carry out a method as described above. In this way, a drive system can be provided in order to implement the previously described method according to the invention, so that its properties and advantages can be used.

According to one aspect of the present invention, the switching unit has an H-bridge, preferably it is an H-bridge. This can create a simple possibility of creating the necessary measurement conditions which are required for detecting the induced voltage when the motor current is equal to zero and which can offer the previously described possibilities of the method according to the invention.

The present invention also relates to a household appliance component, preferably a drain pump, a condensate pump or a fan, with a drive system as described above. In this way, the properties and advantages of a drive system according to the invention can be used in a household component.

The present invention also relates to a household appliance, preferably a washing machine or a dishwasher, with a household appliance component as described above. In this way, the properties and advantages of a household component according to the invention can be used in a household appliance.

• 1 eine schematische Darstellung eines erfindungsgemäßen Antriebssystems;
• 2 eine schematische Darstellung einer Regelungseinheit des erfindungsgemäßen Antriebssystems;
• 3 eine schematische Darstellung einer Berechnungseinheit, einer Schaltereinheit sowie eines Einphasen-Synchronmotors des erfindungsgemäßen Antriebssystems;
• 4 ein schematisches Ablaufdiagramm eines erfindungsgemäßen Verfahrens;
• 5-7 drei Messdiagramme einer ersten Konstellation von Nulldurchgang des Motorstroms und erfassten induzierten Spannungen;
• 8-10 drei Messdiagramme einer zweiten Konstellation von Nulldurchgang des Motorstroms und erfassten induzierten Spannungen;
• 11-13 drei Messdiagramme einer dritten Konstellation von Nulldurchgang des Motorstroms und erfassten induzierten Spannungen; und
• 14-16 drei Messdiagramme einer vierten Konstellation von Nulldurchgang des Motorstroms und erfassten induzierten Spannungen.

An embodiment of the invention is shown purely schematically in the drawings and is described in more detail below. It shows

• 1 a schematic representation of a drive system according to the invention;
• 2 a schematic representation of a control unit of the drive system according to the invention;
• 3 a schematic representation of a calculation unit, a switch unit and a single-phase synchronous motor of the drive system according to the invention;
• 4th a schematic flow diagram of a method according to the invention;
• 5-7 three measurement diagrams of a first constellation of zero crossing of the motor current and detected induced voltages;
• 8-10 three measurement diagrams of a second constellation of zero crossing of the motor current and detected induced voltages;
• 11-13 three measurement diagrams of a third constellation of zero crossing of the motor current and detected induced voltages; and
• 14-16 three measurement diagrams of a fourth constellation of zero crossing of the motor current and recorded induced voltages.

1 shows a schematic representation of a drive system according to the invention 1- 4th . 2 shows a schematic representation of a control unit 2 of the drive system according to the invention 1-4 . 3 shows a schematic representation of a calculation unit 3 , a switch unit 4th as well as a single-phase synchronous motor 1 of the drive system according to the invention 1 - 4th .

The drive system according to the invention 1 indicates the single-phase synchronous motor 1 on which a stator 10 , also stand 10 called, and a rotor that can be rotated for this purpose 11 , also runners 11 called, owns. The stator 10 has electrically conductive windings (not shown) via which a motor voltage U_motor can be applied to a motor current I_motor to create. The motor voltage U_motor can through the voltage divider 13 tapped and as a measured value Umotor to provide. The rotor 11 has a permanent magnet 12 with a north pole 12a and with a south pole 12b on, see e.g. 1 and 3 .

The control unit 2 has two inputs via which target values can be specified. These specified target values can be changed. On the one hand, these are the specification of a setpoint value for the electrical rotational frequency Frequency_ref and on the other hand, the specification of a setpoint value for the induced voltage Bemf_ref . Furthermore, the control unit 2 a measured value of a sensed induced voltage Bemf_Sample fed to the stator 10 of the single-phase synchronous motor 1 can be detected, see 1 .

The control unit 2 has a phase regulator 20th which is the setpoint of the induced voltage Bemf_ref and the detected induced voltage Bemf_Sample are fed. From the difference between the nominal value of the induced voltage Bemf_ref and the detected induced voltage Bemf_Sample an electrical frequency of a reference voltage is generated via a controller (shown here as a PI controller as an example) Uref Frequency generated, which on the one hand to generate the reference voltage Uref even as the output signal of the control unit 2 is used and on the other hand as an input variable of a speed controller 21st serves. The speed controller 21st receives in addition to that from the phase regulator 20th generated electrical frequency of the reference voltage Uref Frequency the setpoint of the electrical rotation frequency Frequency_ref and generates an amplitude of the reference voltage from their difference Uref amplitude , please refer 2 .

The calculation unit 3 receives the reference voltage as the input variable Uref the control unit 2 and generates four switching signals S. as pulse-width-modulated signals which the switching unit 4th are fed. The calculation unit 3 has a software module which calculates the switching times of the pulse-width modulated signals of the switching signals S. takes over, so that the switching unit 4th according to the reference voltage Uref can be controlled and operated.

The switching unit 4th is as an H-bridge 4th formed and accordingly has four switches 40 on which as circuit breakers 40 in the form of four MOSFETs 40 or four IGBTs 40 can be formed. The four switches 40 connect a direct voltage Udc to a potential GND and also generate the motor terminal voltage (not labeled). In the realm of potential GND is a shunt 41 for converting the motor current I_motor provided in a voltage signal so that the motor current I_motor as a measured value Imotor can be made available. Optionally, the measured value Imotor of the motor current I_motor by means of an amplifier 42 be reinforced.

4th shows a schematic flow diagram of a method according to the invention which is carried out with the drive system according to the invention 1-4 of the 1 to 3 can be executed.

There is initially an operation 100 of the single-phase synchronous motor 1 with a first electrical frequency of the reference voltage Uref Frequency and with a first electrical amplitude of the reference voltage Uref amplitude . During operation 100 an interruption occurs at a predetermined point in time 200 the operation of the single-phase synchronous motor 1 for a measurement period T_mess , where the measurement period T_mess a zero crossing of the motor current I_motor includes, see 5 to 16 . Within the measurement period T_mess takes place at the time of the zero crossing of the motor current I_motor a capture 300 the voltage induced at that moment Bemf_Sample . The detected induced voltage Bemf_Sample corresponds to the electromotive force, since there is no motor current at this moment I_motor flows.

A comparison now takes place 400 the detected induced voltage Bemf_Sample with the setpoint of the induced voltage Bemf_ref . In response to this, in the event that according to the comparing 400 the detected induced voltage Bemf_Sample the setpoint of the induced voltage Bemf_ref corresponds to the first electrical frequency of the reference voltage Uref Frequency retained and in the subsequent operation 800 of the single-phase synchronous motor 1 as the second electrical frequency of the reference voltage Uref Frequency is used, as will be described below.

However, if it happens that according to the comparing 400 the detected induced voltage Bemf_Sample not the setpoint of the induced voltage Bemf_ref corresponds, a change takes place 500 the second electrical frequency of the reference voltage Uref Frequency compared to the first electrical frequency of the reference voltage Uref Frequency , ie during the subsequent operation 800 of the single-phase synchronous motor 1 is used as the second electrical frequency of the reference voltage Uref Frequency another frequency of the reference voltage Uref Frequency than the previous first frequency of the reference voltage Uref Frequency is used, as will be described below.

• Für den Fall, dass der Nulldurchgang des Motorstroms I_motor von Positiv nach Negativ erfolgt und dass die Differenz zwischen der erfassten induzierten Spannung Bemf_Sample und dem Sollwert der induzierten Spannung Bemf_ref positiv ist, führt das Verändern 500 der zweiten elektrischen Frequenz der Referenzspannung Uref Frequency gegenüber der ersten elektrischen Frequenz der Referenzspannung Uref Frequency zu einem Verringern der ersten elektrischen Frequenz der Referenzspannung Uref Frequency , siehe 5 bis 7.
• Dies entspricht einem Betreiben 100 des Einphasen-Synchronmotors 1, bei dem die erfasste induzierte Spannung Bemf_ref positiv dem Motorstrom I_motor nacheilt, d.h. der Einphasen-Synchronmotor 1 langsamer als die elektrische Frequenz ω dreht.

Here, four cases can be distinguished as follows, depending on from where to where the zero crossing of the motor current I_motor takes place and whether the difference between the detected induced voltage Bemf_Sample and the nominal value of the induced voltage Bemf_ref is positive or negative:

• In the event that the zero crossing of the motor current I_motor from positive to negative and that the difference between the detected induced voltage Bemf_Sample and the nominal value of the induced voltage Bemf_ref is positive leads to change 500 the second electrical frequency of the reference voltage Uref Frequency compared to the first electrical frequency of the reference voltage Uref Frequency to a lowering of the first electrical frequency of the reference voltage Uref Frequency , please refer 5 to 7th .
• This corresponds to an operation 100 of the single-phase synchronous motor 1 at which the detected induced voltage Bemf_ref positive to the motor current I_motor lagging, ie the single-phase synchronous motor 1 slower than the electrical frequency ω turns.

Thus, in response to this, the subsequent operation 800 of the single-phase synchronous motor 1 its second electrical frequency of the reference voltage Uref Frequency compared to the first electrical frequency of the reference voltage Uref Frequency decreased, resulting in a decrease in the difference between the detected induced voltage Bemf_Sample and the nominal value of the induced voltage Bemf_ref leads. The lowering of the first electrical frequency becomes the reference voltage Uref Frequency carried out repeatedly over several sequences of the method according to the invention, see 5 and 6 until the difference between the detected induced voltage Bemf_Sample and the nominal value of the induced voltage Bemf_ref is balanced, see 7th .

In the event that the zero crossing of the motor current I_motor from positive to negative and that the difference between the detected induced voltage Bemf_Sample and the nominal value of the induced voltage Bemf_ref negative leads to change 500 the second electrical frequency of the reference voltage Uref Frequency compared to the first electrical frequency of the reference voltage Uref Frequency to increase the first electrical frequency of the reference voltage Uref Frequency . In this case the detected induced voltage rushes Bemf_ref the motor current I_motor ahead, ie the single-phase synchronous motor 1 faster than the electrical frequency ω turns. This phase difference is created by increasing the first electrical frequency of the reference voltage Uref Frequency counteracted, see 8th to 10 .

In the event that the zero crossing of the motor current I_motor from negative to positive and that the difference between the detected induced voltage Bemf_Sample and the nominal value of the induced voltage Bemf_ref is positive leads to change 500 the second electrical frequency of the reference voltage Uref Frequency compared to the first electrical frequency of the reference voltage Uref Frequency to increase the first electrical frequency of the reference voltage Uref Frequency . In this case, too, the detected induced voltage rushes Bemf_ref the motor current I_motor ahead, ie the single-phase synchronous motor 1 rotates faster than the electrical frequency ω so that from this phase difference by increasing the first electrical frequency of the reference voltage Uref Frequency can be counteracted, see 11 to 13 .

In the event that the zero crossing of the motor current I_motor from negative to positive and that the difference between the detected induced voltage Bemf_Sample and the nominal value of the induced voltage Bemf_ref negative leads to change 500 the second electrical frequency of the reference voltage Uref Frequency compared to the first electrical frequency of the Reference voltage Uref Frequency to a lowering of the first electrical frequency of the reference voltage Uref Frequency . In this case, too, the detected induced voltage rushes Bemf_ref the motor current I_motor after, ie the single-phase synchronous motor 1 rotates slower than the electrical frequency ω so that also this phase difference by reducing the first electrical frequency of the reference voltage Uref Frequency can be counteracted, see 14th to 17th .

In all four cases the setpoint is the induced voltage Bemf_ref equal to zero, so that due to this specification of the setpoint of the induced voltage Bemf_ref instead of the difference between the detected induced voltage Bemf_Sample and the nominal value of the induced voltage Bemf_ref directly the detected induced voltage Bemf_Sample can be viewed. An optimal operating point can also be set in this way, since, if so, the detected induced voltage Bemf_Sample the setpoint of the induced voltage Bemf_ref corresponds to the detected induced voltage Bemf_Sample equals zero and thus the detected induced voltage Bemf_Sample and the motor current I_motor are in phase with each other.

A comparison takes place in a further step 600 the second electrical frequency of the reference voltage Uref Frequency with a setpoint of the electrical rotational frequency Frequency_ref, with renewed operation 800 of the single-phase synchronous motor 1 furthermore with a second electrical amplitude of the reference voltage Uref amplitude depending on the result of the comparison 600 he follows. Also with regard to the first and second electrical amplitude of the reference voltage Uref amplitude holds that in the event that according to the comparing 600 the second electrical frequency of the reference voltage Uref Frequency the nominal value of the electrical rotational frequency Frequency_ref corresponds to the subsequent operation 800 of the single-phase synchronous motor 1 with an unchanged first electrical amplitude of the reference voltage Uref amplitude takes place, ie the second electrical amplitude of the reference voltage Uref amplitude the first electrical amplitude of the reference voltage Uref amplitude corresponds.

However, in the event that according to the comparing is done 600 the second electrical frequency of the reference voltage Uref Frequency not the setpoint of the electrical rotational frequency Frequency_ref corresponds to a change 700 the second electrical amplitude of the reference voltage Uref amplitude compared to the first electrical amplitude of the reference voltage Uref amplitude . For this purpose, the setpoint of the electrical rotational frequency Frequency_ref, which is a predetermined mechanical speed of the single-phase synchronous motor 1 can be increased or decreased. This has a corresponding effect on the second electrical amplitude of the reference voltage Uref amplitude from which the operation of the single-phase synchronous motor via the reference voltage U_ref 1 influences and the phase position of the induced voltage Bemf_Sample compared to the motor current I_motor upset. The phase controller then acts on the detuned phase position 20th the control unit 2 counter to the induced voltage Bemf_Sample compared to the motor current I_motor is back in phase, but at the predetermined mechanical speed of the single-phase synchronous motor 1 which was specified by the setpoint of the electrical rotational frequency Frequency_ref.

In any case, it is operated again 800 of the single-phase synchronous motor 1 with a second electrical frequency of the reference voltage Uref Frequency depending on the result of the comparison 400 and with the second electrical amplitude of the reference voltage Uref amplitude depending on the result of the comparison 600 .

List of reference symbols

Amplitude, Uampl

electrical amplitude of the reference voltage Uref (Manipulated variable)

Bemf_ref

Setpoint of the induced voltage at the time of the current zero crossing

Bemf_Sample

induced voltage (back electromotive force) at the time of the current zero crossing

Frequency, f

electrical frequency of the reference voltage Uref (Manipulated variable)

Frequency_ref

Setpoint of the electrical rotational frequency

GND

Ground potential

I_motor

Motor current

Imotor

Measured value of the motor current I_Motor

S.

Switching signals

t

time

T_Bemf

Measurement time of the setpoint of the induced voltage Bemf_ref

T_mess

Measurement period

U_dc

DC voltage

U_motor

Motor voltage

Umotor

Measured value of the motor voltage U_Motor

Uref

Reference voltage (manipulated variable)

ω

electrical speed

1

Single-phase synchronous motor

10

Stator; Stand

11

Rotor; runner

12

Permanent magnet

12a

North Pole

12b

South Pole

13

Voltage divider

2

Control unit

20th

Phase regulator

21st

Speed controller

22nd

Reference voltage generator

3

Calculation unit

4th

Switching unit; H-bridge

40

Counter; Circuit breaker

41

Shunt

42

amplifier

100

Operate single-phase synchronous motor 1 with the first electrical frequency of the reference voltage Uref Frequency and with the first electrical amplitude of the reference voltage Uref amplitude

200

Interrupt operation of the single-phase synchronous motor 1 for measurement period T_mess

300

Acquire induced voltage Bemf_Sample

400

Compare detected induced voltage Bemf_Sample with setpoint of the induced voltage Bemf_ref

500

Change the second electrical frequency of the reference voltage Uref Frequency compared to the first electrical frequency of the reference voltage Uref Frequency

600

Compare the second electrical frequency to the reference voltage Uref Frequency with setpoint of the electrical rotational frequency Frequency_ref

700

Change the second electrical amplitude of the reference voltage Uref amplitude compared to the first electrical amplitude of the reference voltage Uref amplitude

800

renewed operation of the single-phase synchronous motor 1 with the second electrical frequency of the reference voltage Uref Frequency and with the second electrical amplitude of the reference voltage Uref amplitude

Claims (16)

Method for operating a drive system (1-4) with a single-phase synchronous motor (1) with at least the following steps: operating (100) the single-phase synchronous motor (1) with a first electrical frequency (Frequency) of a reference voltage (Uref), interrupting ( 200) the operation of the single-phase synchronous motor (1) for a measuring period (T_mess), the measuring period (T_mess) including a zero crossing of a motor current (I_motor) within the measuring period (T_mess) at the time of the zero crossing of the motor current (I_ motor), detecting (300) an induced voltage (Bemf_Sample), comparing (400) the detected induced voltage (Bemf_Sample) with a setpoint value of the induced voltage (Bemf_ref) and re-operating (800) the single-phase synchronous motor (1) with a second electrical frequency (Frequency) of the reference voltage (Uref) as a function of the result of the comparison (400). Procedure according to Claim 1 , in the event that according to the comparison (400) the detected induced voltage (Bemf_Sample) corresponds to the setpoint value of the induced voltage (Bemf_ref), the second electrical frequency (Frequency) of the reference voltage (Uref) of the first electrical frequency (Frequency) of the Reference voltage (Uref). Procedure according to Claim 1 or 2 In the event that, according to the comparison (400), the detected induced voltage (Bemf_Sample) does not correspond to the setpoint value of the induced voltage (Bemf_ref), at least one further step takes place: changing (500) the second electrical frequency (Frequency) of the reference voltage (Uref) compared to the first electrical frequency (Frequency) of the reference voltage (Uref). Procedure according to Claim 3 In the event that the zero crossing of the motor current (I_motor) takes place from positive to negative and that the difference between the detected induced voltage (Bemf_Sample) and the setpoint of the induced voltage (Bemf_ref) is positive, changing (500) the second electrical frequency (Frequency) of the reference voltage (Uref) compared to the first electrical frequency (Frequency) of the reference voltage (Uref) leads to a reduction in the first electrical frequency (Frequency) of the reference voltage (Uref). Procedure according to Claim 3 or 4th , in the event that the zero crossing of the motor current (I_motor) takes place from positive to negative and that the difference between the detected induced voltage (Bemf_Sample) and the setpoint of the induced voltage (Bemf_ref) is negative, changing (500) the second electrical frequency (Frequency) of the reference voltage (Uref) compared to the first electrical frequency (Frequency) of the reference voltage (Uref) leads to an increase in the first electrical frequency (Frequency) of the reference voltage (Uref). Method according to one of the Claims 3 to 5 In the event that the zero crossing of the motor current (I_motor) takes place from negative to positive and that the difference between the detected induced voltage (Bemf_Sample) and the setpoint value of the induced voltage (Bemf_ref) is positive, changing (500) the second electrical frequency (Frequency) of the reference voltage (Uref) compared to the first electrical frequency (Frequency) of the reference voltage (Uref) leads to an increase in the first electrical frequency (Frequency) of the reference voltage (Uref). Method according to one of the Claims 3 to 6 , in the event that the zero crossing of the motor current (I_motor) takes place from negative to positive and that the difference between the detected induced voltage (Bemf_Sample) and the setpoint of the induced voltage (Bemf_ref) is negative, changing (500) the second electrical frequency (Frequency) of the reference voltage (Uref) compared to the first electrical frequency (Frequency) of the reference voltage (Uref) leads to a reduction in the first electrical frequency (Frequency) of the reference voltage (Uref). Method according to one of the preceding claims, wherein the desired value of the induced voltage (Bemf_ref) is equal to zero. Method according to one of the preceding claims, wherein the operation (100) of the single-phase synchronous motor (1) with the first electrical frequency (Frequency) of the reference voltage (Uref) also takes place with a first electrical amplitude (amplitude) of the reference voltage (Uref), and the method further comprises at least the further step: Comparing (600) the second electrical frequency (Frequency) of the reference voltage (Uref) with a setpoint value of the electrical rotational frequency (Frequency_ref), wherein the renewed operation (800) of the single-phase synchronous motor (1) also takes place with a second electrical amplitude (amplitude) of the reference voltage (Uref) as a function of the result of the comparison (600). Procedure according to Claim 9 In the event that, according to the comparison (600), the second electrical frequency (Frequency) of the reference voltage (Uref) corresponds to the setpoint value of the electrical rotational frequency (Frequency_ref), the second electrical amplitude (amplitude) of the reference voltage (Uref) of the first electrical Amplitude (amplitude) corresponds to the reference voltage (Uref). Procedure according to Claim 9 or 10 In the event that, according to the comparison (600), the second electrical frequency (Frequency) of the reference voltage (Uref) does not correspond to the setpoint value of the electrical rotational frequency (Frequency_ref), at least the further step takes place: changing (700) the second electrical amplitude (Amplitude) of the reference voltage (Uref) compared to the first electrical amplitude (amplitude) of the reference voltage (Uref). Method according to one of the Claims 9 to 11 , wherein the setpoint of the electrical rotational frequency (Frequency_ref) corresponds to a predetermined mechanical speed of the single-phase synchronous motor (1). Drive system (1-4) with a single-phase synchronous motor (1), with a switching unit (4) which is designed to operate the single-phase synchronous motor (1) with a first and a second electrical frequency (Frequency) of a reference voltage (Uref), preferably also with a first and a second electrical amplitude (amplitude) the reference voltage (Uref) to operate, wherein the switching unit (4) is further designed to interrupt the operation of the single-phase synchronous motor (1) for a measurement period (T_mess), wherein the measurement period (T_mess) includes a zero crossing of a motor current (I_motor), wherein the single-phase synchronous motor (1) is designed to detect an induced voltage (Bemf_Sample) within the measurement period (T_mess) at the time of the zero crossing of the motor current (I_motor), wherein the drive system (1-4), preferably a control unit (2) of the drive system (1-4), is designed to carry out a method according to one of the preceding claims. Drive system (1-4) Claim 13 , wherein the switching unit (4) has an H-bridge (4), preferably an H-bridge (4). Household appliance component, preferably a drain pump, condensate pump or fan, with a drive system Claim 13 or 14th . Household appliance, preferably washing machine or dishwasher, with a household appliance component Claim 15 .

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