METHOD FOR CONTROLLING A COMPRESSOR SYSTEM, COMPRESSOR FOR COMPRESSING A WORKING MEDIUM, COMPRESSOR SYSTEM AND REFRIGERATION CIRCUIT SYSTEM FOR CARRYING OUT A REFRIGERATION CYCLE PROCESS

Description

TECHNICAL FIELD

The present invention relates to a method for controlling a compressor system, a compressor for compressing a working medium and a refrigeration circuit system for carrying out a refrigeration cycle process.

BACKGROUND OF THE INVENTION

From the prior art, systems for heating, ventilation and air conditioning, so-called HVAC systems (HVAC systems) are known, with which, among other things, a targeted and also as efficient as possible control of temperature, air humidity or air flow within a building or partial areas thereof is to be implemented.

Recently, for this purpose, refrigeration circuit systems, for example in the form of heat pumps or refrigeration machines, are increasingly used as a component of such HVAC systems, especially in private households, optionally as part of a heating system of the HVAC system for increasing room temperatures, but also as part of an air conditioning system of the HVAC system for lowering room temperatures.

Such refrigeration circuit systems are thermodynamically operating systems, which make various ambient energy sources, for example in the form of aerothermia, geothermia or hydrothermia, usable for heating and/or for air conditioning via a connection to a heat source system. For this purpose, the refrigeration circuit system is set up for carrying out a thermodynamic refrigeration cycle process, in the course of which a working medium of the refrigeration circuit system is compressed and expanded as well as heated and cooled according to the generally known principles, in such a way that heat energy can be transferred to the working medium at at least one point of the refrigeration circuit system and heat energy can be extracted from the working medium at at least one further point, in order thus to implement a heat flow from or into a target system, e.g. a room of a building.

In the cases in which heat energy is to be extracted from the target system, for example in the area of air conditioning, the refrigeration circuit system is often also referred to as a refrigeration machine, whereas in cases in which heat energy is supplied to the target system, heat pumps are often also referred to.

In the following, both such refrigeration machines and heat pumps are to be understood as being combined under the generic term “refrigeration circuit system”.

In this case, the essential element in the refrigeration circuit system is the usually electrically operated compressor, via which the working medium is compressed in order to increase the pressure thereof. For supplying power, the electrical compressor is usually connected to a grid connection point of a grid current source providing alternating current (also referred to as a grid in the following).

In this case, the compressor taps the current necessary for operation from the grid current source, wherein the tapped current must not exceed certain limit values, which are defined in particular for multiples of the fundamental frequency of the grid and are thus limit values of a harmonic content, since the operation of the compressor otherwise has a negative effect on the grid itself. These limit values are generally also predetermined by law.

In the prior art, in order to maintain these limit values, additional inductive elements are usually used, which are provided in an interface to the grid connection point and which damp the tapped current in order to reduce the harmonic content.

However, such arrangements are highly lossy and not very flexible with regard to changing operating states and/or ambient conditions. Furthermore, these additional costs arise and they take up installation space.

SUMMARY

An object of the present invention is therefore to provide a more efficient, in particular more cost-effective and more installation space-saving, and more flexible option, with which negative effects for the grid during operation of a compressor system can be reduced as far as possible without energy losses, in order thus in particular to comply with the legal requirements.

In order to achieve this object, a method according to claim 1, a compressor according to claim 15, a compressor system according to claim 16 and a refrigeration circuit system according to claim 17 are provided.

The respective dependent claims relate here to preferred embodiments which can be provided in each case by themselves or in combination.

According to one aspect of the invention, a method for controlling a compressor system is provided, which is in particular part of a refrigeration circuit system, and which comprises an electrically operated compressor, which is configured for compressing a working medium, and a further electrical load. The compressor in turn comprises an electric motor for providing a mechanical movement for compressing the working medium, an inverter, which supplies the electric motor with single- or multi-phase alternating current, a power factor correction filter (PFC) power factor compensation), which supplies the inverter with direct current and whose current input for supplying power to the compressor is connected to a grid connection point of a grid current source providing alternating current. For supplying power, the further electrical load is connected to the same grid connection point as the power factor correction filter. The method comprises operating the compressor system with electrical current from the grid current source, determining at least one current characteristic value of the further load, which describes a current consumption of the further load, and controlling the power factor correction filter of the compressor at least in dependence of the determined at least one current characteristic value of the further load.

Preferably, a plurality of current characteristic values of the further load are determined, so that the determining of the at least one current characteristic value of the further load is a determining of a plurality of current characteristic values of the load, which describe a current consumption of the further load, and the controlling of the power factor correction filter of the compressor takes place correspondingly at least in dependence of the determined plurality of current characteristic values of the further load.

In the context of this application, deviating from the usual use of the term “compressor” and as defined in claim 1, the power electronics (power factor correction filter) connected upstream of the electromechanical component (electric motor) are also to be understood as part of the compressor.

Power factor correction filters, also abbreviated to PFC, are electrical or electronic circuits which increase the power factor reduced by distortion reactive power, wherein the power correction filter of the provided compressor system is preferably an active power correction filter.

By means of the procedure according to the invention, a control of a compressor system on the basis of the power factor correction filter of the compressor comprised therein can be implemented in order thus to increase the power factor of the entire compressor system, that is to say including the further load.

Said further load, which is connected to the same grid connection point as the compressor, usually comprises a passive rectifier which supplies a DC load of the further load with direct current.

On account of the mode of operation of such a rectifier, the latter likewise generates feedback effects, in particular in the form of harmonics in the electrical current tapped at the grid connection point.

Although a harmonic content of the tapped current of individual components corresponds to the normative specifications or limit values, this does not necessarily apply to a combination of all the loads which are connected to the grid connection point.

The inventors have found that, for the described construction of the compressor system, said limit values of the resulting tapped current can be maintained by a targeted controlling of the power correction factor of the compressor without in this case having to make changes to the further load itself, for example in the form of additional damping (and therefore lossy) inductances or even of a separately provided power factor correction filter at the further load.

In this case, harmonics generated by the further load can be compensated in an advantageous manner by taking into account the current characteristic value at the further load during the controlling of the power factor correction filter of the compressor.

In this way, the described compressor system can maintain normative specifications during the tapping of the electrical current from the grid current source without the further load having to be structurally modified or supplemented by additional components.

In this respect, the method permits an efficient operation of a compressor system, in which in particular energy losses are kept low. Furthermore, the described procedure can be used for a multiplicity of different or even a plurality of further loads, wherein the maintenance of the normative specifications can be ensured merely by controlling the power correction filter of the compressor.

It is preferably an active power factor correction filter which, although configured more complexly in comparison with a passive circuit, achieves better power correction factors in comparison with the latter.

The power factor correction filter preferably comprises a rectifier and a step-up converter connected downstream of the latter with respect to an energy flow direction from the grid current source to the electric motor. A step-up converter is a form of a DC voltage converter, the output voltage of which is generally higher than the input voltage thereof.

The rectifier can be configured passively or actively and is preferably configured as a passive bridge rectifier.

The further electrical load is preferably a combination of a rectifier, in particular a passive rectifier, and a DC load (DC, direct current).

The further load comprises in particular no dedicated power factor correction filter, or at least one power factor correction filter, the power factor correction of which is smaller than that of the power factor correction filter of the compressor.

In this case, the DC load can be a DC fan unit or a DC electric motor thereof, specifically in the case of a refrigeration circuit system.

The grid current source can be, for example, both a 1-phase and a 3-phase grid current source. In other words, said grid current source can provide, for example, 1-phase alternating current or 3-phase alternating current (so-called three-phase current) via the grid connection point.

In this case, the method is not restricted to a specific embodiment of the grid current source. Depending on the embodiment of the grid current source, the structure differs between compressor and further load, the current inputs of which are designed, by way of example, for either 1-phase or 3-phase alternating current.

As also in the case of the grid current source, the electric motor of the compressor can be an electric motor which is operated with 1-phase or multi-phase alternating current, in particular 3-phase alternating current Correspondingly, the inverter is of course set up to provide 1-phase or multi-phase alternating current at its output.

In a preferred embodiment, the controlling of the power factor correction filter comprises setting an operating parameter of the power factor correction filter, which determines the direct current output by the power factor correction filter, at least in dependence of the determined at least one or the determined plurality of current characteristic values of the further load.

In a preferred embodiment, the power factor correction filter comprises at least one transistor unit, in particular a MOSFET or an IGBT, and the setting of the operating parameter of the power factor correction filter for controlling the power factor correction filter in turn comprises setting a control signal of the at least one transistor unit at least in dependence of the determined at least one or the determined plurality of current characteristic values of the further load.

As a result, an easily implementable option for control is provided, in which the control signal of the transistor unit is an adjusting screw.

In a preferred embodiment, the at least one determined current characteristic value is an electrical current strength, in particular an effective electrical current strength, or an electrical power, in particular an effective electrical power. Preferably, in the case of a plurality of current characteristic values, these are likewise an electrical current strength, in particular an effective electrical current strength, or an electrical power, in particular an effective electrical power, in particular for different frequencies.

By using effective values, the control can be kept particularly simple, so that control times can be reduced.

In a preferred embodiment, the further load and the compressor are connected parallel to one another at the grid connection point.

In a preferred embodiment, the determining of the at least one or the plurality of current characteristic values of the further load comprises detecting a current variable of an electrical current present at a current input of the further load, in particular a current strength, and determining the at least one or the plurality of current characteristic values on the basis of the detected current variable.

The detection of the current variable can take place here via suitable measuring means, for example in the simplest case via voltmeters and/or ammeters. The determining of the at least one or the plurality of current characteristic values on the basis of the detected current variable can be, for example, determining one or more effective values.

In a preferred embodiment, the determining of the at least one or the plurality of current characteristic values of the further load comprises providing a calculation model, which describes the electrical structure of the further load, comprising one or more electrical characteristic variables of the further load, partially or completely, calculating the at least one or the plurality of current characteristic values on the basis of the provided calculation model and outputting the calculated at least one or the calculated plurality of current characteristic values as a determined current characteristic value or as a determined plurality of current characteristic values of the further load.

As a result, an alternative to detecting the current variable via measuring means is provided, so that the current characteristic value or the current characteristic values of the further load can be determined basically without measuring current variables at the further load. As a result, a corresponding measurement structure at the further load can be dispensed with, as a result of which costs and installation space are saved.

The calculation model describes the electrical structure of the further load and is suitable for determining electrical state variables of the further load in dependence on an input current present at the load, for example specified by current strength and/or voltage at the input.

In this case, the calculation model can be kept simple, in particular for the case in which the further load corresponds to a combination of rectifier and DC load, and is additionally distinguished by fast calculation times and representative results, so that the accuracy of this procedure does not hinder a direct detection of the current variable at the further load.

Characteristic variables of the further load can be, for example and without limitation, resistances, capacitances or inductances of the further load.

Rated operating values of the DC load, for example a rated power or a rated current strength, are preferably used as an input variable for the calculation model.

In a preferred embodiment, the power factor correction filter comprises a rectifier with an input for alternating current and an output for rectified output current.

The input of the rectifier is connected to the current input of the power factor correction filter. This can take place directly or via further interposed electrical components, such as, for example, inductances, capacitances or resistances.

In particular, the rectifier of the power factor correction filter is a bridge rectifier.

In a preferred embodiment, the method further comprises detecting a current variable of the output current of the rectifier at the output of the rectifier, in particular a current strength or a voltage, wherein the controlling of the power factor correction filter of the compressor takes place in additional dependence on the detected current variable of the output current of the rectifier.

As a result, the control of the power factor correction filter is extended by further input variables, as a result of which a more precise control is made possible.

In this case, the current variable can be detected, for example, as a discrete value, as a time profile or as an effective value.

In a preferred embodiment, the power factor correction filter comprises a totem-pole PFC converter.

A totem-pole PFC converter is generally formed by a push-pull output stage made of bipolar or field-effect transistors and is optimized for high switching speed. By using such a totem-pole PFC converter, in particular additional passive rectifiers, such as, for example, bridge rectifiers, as part of the power factor correction filter can be dispensed with.

In an embodiment preferred in this respect, the method further comprises detecting a current variable of an input current of the totem-pole PFC converter, in particular a current strength or a voltage, wherein the controlling of the power factor correction filter of the compressor takes place in additional dependence on the detected current variable of the input current of the totem-pole PFC converter.

In a preferred embodiment, the method further comprises detecting a current variable of an output current of the totem-pole PFC converter, in particular a current strength or a voltage, at an output of the totem-pole PFC converter connected to the inverter, wherein the controlling of the power factor correction filter of the compressor takes place in additional dependence on the detected current variable of the output current of the totem-pole PFC converter.

In a preferred embodiment, the method further comprises detecting a current variable of an electrical current present at the current input of the power factor correction filter, in particular a current strength or a voltage, wherein the controlling of the power factor correction filter of the compressor takes place in additional dependence on the detected current variable of the electrical current present at the current input of the power factor correction filter.

In this case, the current variable can be detected, for example, as a discrete value, as a time profile or as an effective value.

As a result, the controlling of the power factor correction filter is extended by further input variables, as a result of which a more precise control is made possible.

In a preferred embodiment, the controlling of the power factor correction filter takes place under the provision that one or more characteristic values of an electrical current tapped from the compressor system at the grid connection point lie below a respectively predetermined limit value.

As a result, in particular specifications with respect to the harmonic content can be maintained.

Said characteristic value can be, for example, a harmonic content at certain frequencies, but also an average value formed therefrom.

In a preferred embodiment, the one or more characteristic values are amplitude values from a frequency spectrum of the tapped electrical current, in particular amplitude values for frequencies which correspond to an integral multiple of the fundamental frequency of the grid current source (also referred to as harmonics).

The frequency spectrum offers a simple and fast option for determining a harmonic content of the tapped electrical current.

In the case of a plurality of characteristic values, each characteristic value preferably corresponds to an amplitude value of a different frequency.

The frequency spectrum is, in particular, a frequency spectrum of the voltage of the tapped electrical current. Alternatively, and without limitation, however, it can also be a frequency spectrum of the current strength.

In a preferred embodiment, the compressor system is designed as part of a refrigeration circuit system, which is in particular a heat pump or a refrigeration machine, and the method is a method for controlling the refrigeration circuit system.

According to a second aspect of the invention, a compressor for compressing a working medium is provided, which comprises an electric motor for providing a mechanical movement for compressing the working medium, an inverter, which supplies the electric motor with single- or multi-phase alternating current, a power factor correction filter, which supplies the inverter with direct current and whose current input for supplying power to the compressor is connectable to a grid connection point of a grid current source providing alternating current, and a control device, which is configured at least for controlling the power factor correction filter. In the event that the compressor and a further electrical load are connected to the same grid connection point of a grid current source providing alternating current, the control device is configured to determine at least one current characteristic value or a plurality of current characteristic values of the further load, which each describe a current consumption of the further load, and to control the power factor correction filter at least in dependence of the determined at least one or the plurality of current characteristic values of the further load.

In this way, a compressor is provided, which, when connected to a grid connection point, together with a further electrical load, is configured for implementing the method described above.

The advantages resulting therefrom substantially correspond to those of the method and will not be explained again at this point.

The further electrical load preferably comprises a rectifier, in particular a passive rectifier, and a DC load.

According to a third aspect of the invention, a compressor system is provided, which is in particular part of a refrigeration circuit system. The compressor system comprises an electrically operated compressor for compressing a working medium according to the second aspect or one of the preferred embodiments thereof, and a further electrical load. The compressor and the further load are provided to be connected to a same grid connection point of a grid current source providing alternating current, wherein for this case the control device of the compressor is configured to determine at least one current characteristic value or a plurality of current characteristic values of the further load, which describes a current consumption of the further load, and to control the power factor correction filter at least in dependence of the determined at least one or the plurality of current characteristic values of the further load.

In this way, a compressor system is provided, which is configured for implementing the method described above.

The advantages resulting therefrom substantially correspond to those of the method and will not be explained again at this point. The same applies to the specific embodiments described in the following, which largely correspond to the implementation according to the device of the specific and already described embodiments of the method.

The compressor and the further load are preferably connected in the form of a parallel circuit at the grid connection point.

The grid current source can be, for example, both a 1-phase and a 3-phase grid current source. In other words, said grid current source can provide, for example, 1-phase alternating current or 3-phase alternating current (so-called three-phase current) via the grid connection point.

In this case, the compressor system is not restricted to a specific embodiment of the grid current source. Depending on the embodiment of the grid current source, the structure differs between compressor and further load, the current inputs of which are designed, by way of example, for either 1-phase or 3-phase alternating current.

Preferably, in the course of controlling the power factor correction filter, the control device is configured to set an operating parameter of the power factor correction filter, which determines the direct current output by the power factor correction filter and/or which influences the alternating current tapped from the grid current source by the compressor, at least in dependence of the determined at least one or the plurality of current characteristic values of the further load.

Preferably, the power factor correction filter comprises at least one transistor unit, in particular a MOSFET or an IGBT, and in the course of setting the operating parameter of the power factor correction filter, the control device is configured to set a control signal of the at least one transistor unit at least in dependence of the determined at least one or the plurality of current characteristic values of the further load. For this purpose, the control device preferably comprises a PWM calculation unit (PWM: pulse width modulation), which provides the control signal as PWM signal.

Preferably, the compressor system comprises a current measuring means for detecting a current variable of an electrical current present at a current input of the further load, in particular a current strength. The current measuring means is coupled to the control device and the control device is configured to determine the at least one or the plurality of current characteristic values of the further load on the basis of the detected current variable.

Preferably, however, the control device can also determine the current characteristic value or the plurality of current characteristic values of the further load in another way. For this purpose, the control device preferably comprises a calculation model unit, which provides a calculation model, which describes the electrical structure of the further load, comprising one or more electrical characteristic variables of the further load. The calculation model unit is furthermore configured to determine the at least one current characteristic value or the plurality of current characteristic values of the further load on the basis of the provided calculation model and to output these for further use by the control device.

Rated operating values of the further load, for example a rated power or a rated current strength, are preferably used as an input variable for the calculation model. Alternatively or additionally, operating values detected at the further load can also be used for the calculation model.

The power factor correction filter preferably comprises a rectifier with an input for alternating current and an output for rectified output current, which in particular is a bridge rectifier, wherein the input of the rectifier is the current input of the power factor correction filter, which is connectable to the grid connection point.

In the case of such an embodiment with a rectifier, the compressor system preferably comprises a first current measuring means, which is configured to detect a current variable of the output current of the rectifier, in particular a current strength or a voltage, wherein the control device is configured to control the power factor correction filter of the compressor in additional dependence on the current variable of the output current of the rectifier detected by the current measuring means.

Further preferably, the compressor system comprises a current measuring means at the grid connection point, which is configured to detect a current variable of an electrical current present at the current input of the power factor correction filter, in particular a current strength or a voltage, wherein the control device is configured to control the power factor correction filter of the compressor in additional dependence on the current variable of the electrical current present at the current input of the power factor correction filter detected by the further current measuring means.

According to a fourth aspect, a refrigeration cycle system is provided, which is configured to carry out a refrigeration cycle process on the basis of a working medium. In particular, the refrigeration circuit system is a heat pump or a refrigerating machine. The refrigeration cycle system comprises a compressor system, which is designed according to the third aspect or one of the preferred embodiments thereof. The compressor is configured to compress the working medium of the refrigeration cycle system.

The refrigeration cycle system is configured to carry out a refrigeration cycle process, in the course of which the working medium of the refrigeration cycle system is compressed and expanded as well as heated and cooled according to the generally known thermodynamic principles, in such a way that heat energy can be transferred to the working medium at at least one point of the refrigeration cycle system and heat energy can be extracted from the working medium at at least one further point.

Preferably, the refrigeration cycle system for the refrigeration cycle process comprises an expansion device for expanding the working medium, an evaporator for evaporating the working medium and a condenser for condensing the working medium.

In this case, the working medium successively passes through the compressor, the condenser, the expansion device and the evaporator in a repeating cycle, wherein heat energy can be supplied to the working medium at the evaporator and heat energy can be extracted at the condenser. Condenser and evaporator are preferably configured as heat exchangers, for example as lamellar heat exchangers.

The further electrical load preferably comprises a rectifier, in particular a passive rectifier, preferably a bridge rectifier, and a DC load, in particular a DC fan unit and/or a DC circulation pump. The DC fan unit and/or the DC circulation pump is operated with direct current and is supplied with electrical energy from the grid current source via the rectifier.

The working medium is to be understood as any fluid which is suitable for use in a refrigeration cycle system and for this purpose can be compressed, liquefied, expanded and evaporated in said devices, wherein the working medium is usually and without limitation refrigerant, such as, for example, propane or the refrigerant R32, a fluorocarbon.

The DC fan unit is in particular a fan unit of a heat exchanger of the refrigeration circuit system, which is preferably part of an external unit of the refrigeration circuit system. Said heat exchanger can function in particular as an evaporator and/or as a condenser for the working medium of the refrigeration cycle system.

Further aspects and the advantages thereof as well as more specific exemplary embodiments of the aforementioned aspects and embodiments will be described in the following with the aid of the drawings shown in the attached figures.

FIG. 1 schematically shows a flow diagram of a first exemplary embodiment of the method according to the invention.

FIG. 2 schematically shows the structure of a first exemplary embodiment of the compressor system according to the invention.

FIG. 3 schematically shows the structure of a second exemplary embodiment of the compressor system according to the invention.

FIG. 4 schematically shows the structure of a third exemplary embodiment of the compressor system according to the invention.

FIG. 5 schematically shows the structure of a control device of a fourth exemplary embodiment of the compressor system according to the invention.

It is emphasized that the present invention is in no way limited to the exemplary embodiments described in the following and their exemplary features. The invention further comprises modifications of the specified exemplary embodiments, in particular those which result from modifications and/or combinations of individual or a plurality of features of the described exemplary embodiments within the scope of protection of the independent claims.

DETAILED DESCRIPTION OF THE FIGURES

FIG. 1 schematically shows a flow diagram of a first exemplary embodiment of the method according to the invention.

The method is carried out on a compressor system, which comprises an electrically operated compressor, which is configured for compressing a working medium, and a further electrical load. The compressor in turn comprises an electric motor for providing a mechanical movement for compressing the working medium, an inverter, which supplies the electric motor with single- or multi-phase alternating current, a power factor correction filter, which supplies the inverter with direct current and whose current input for supplying power to the compressor is connected to a grid connection point of a grid current source providing alternating current. For supplying power, the further electrical load is connected to the same grid connection point as the power factor correction filter.

In step S1, the compressor system is operated with electrical current from the grid current source.

In step S2, at least one current characteristic value of the further load, which describes a current consumption of the further load, is determined; and

For this purpose, step S2 preferably comprises the substeps S2.1 to S2.3.

In step S2.1, a calculation model is provided, which describes the electrical structure of the further load, comprising one or more electrical characteristic variables of the further load.

In step S2.2, the at least one current characteristic value is calculated on the basis of the calculation model provided in step S2.1.

In step S2.3, the at least one current characteristic value calculated in step S2.2 is output as a determined current characteristic value of the further load.

In step S3, the power factor correction filter of the compressor is controlled at least in dependence of the at least one current characteristic value of the further load determined in step S2.

The method permits harmonics generated by the further load to be compensated in an advantageous manner by taking into account the at least one current characteristic value at the further load during the controlling of the power factor correction filter of the compressor.

In this way, the described compressor system can maintain normative specifications during the tapping of the electrical current from the grid current source without the further load having to be structurally modified or supplemented by additional components, such as, for example, dissipative elements.

In this respect, the method permits an efficient operation of a compressor system, in which in particular energy losses are kept low.

FIG. 2 schematically shows the structure of a first exemplary embodiment of the compressor system 1000 according to the invention.

The compressor system comprises a compressor 1 and a further electrical load 2, which are connected to the same grid connection point 2000 of a grid current source providing alternating current, in particular in the form of a parallel circuit.

The further load 2 preferably comprises a rectifier 21, in particular a passive rectifier, and a DC load 22 supplied with direct current by the latter. Optionally and not necessarily, the further load 2 can also comprise an inductance 24 connected upstream of the rectifier 21.

The compressor 1 is an electrically operated compressor 1 for compressing a working medium, which comprises an electric motor 11 for providing a mechanical movement for compressing the working medium, an inverter 12, a power factor correction filter 13 and a control device 14.

The inverter 12 supplies the electric motor 11 with single- or multi-phase alternating current, in this case with 3-phase alternating current.

The power factor correction filter 13 in turn supplies the inverter 12 with direct current, wherein a current input of the power factor correction filter 13 for supplying power to the compressor 1 is connectable to the grid connection point 2000 or is connected in the exemplary embodiment shown.

The control device 14 is configured at least to control the power factor correction filter 13.

The control device 14 is configured to determine at least one current characteristic value of the further load 2, which describes a current consumption of the further load 2, and to control the power factor correction filter 13 at least in dependence of the determined at least one current characteristic value.

The illustrated compressor system 1000 permits harmonics generated by the further load 2 to be compensated in an advantageous manner by taking into account the at least one current characteristic value at the further load 2 during the controlling of the power factor correction filter 13 of the compressor 1 by the control device 14.

In this way, the compressor system 1000 can maintain normative specifications during the tapping of the electrical current from the grid current source without the further load 2 having to be structurally modified or supplemented by additional components, such as, for example, dissipative elements.

In this respect, an efficiently operable compressor system 1000 is provided, in which in particular energy losses are kept low.

FIG. 3 schematically shows the structure of a second exemplary embodiment of the compressor system according to the invention.

The compressor system 1000 comprises a compressor 1 and a further electrical load 2, which are connected to the same grid connection point 2000 of a grid current source providing alternating current, in particular in the form of a parallel circuit.

The further load 2 preferably comprises a rectifier 21, in particular a passive rectifier, which in the exemplary embodiment shown is configured as a bridge rectifier based on diodes 301, and a DC load 22 supplied with direct current by the latter.

The compressor 1 is an electrically operated compressor 1 for compressing a working medium, which comprises an electric motor 11 for providing a mechanical movement for compressing the working medium, an inverter 12, a power factor correction filter 13 and a control device not illustrated here.

The inverter 12 supplies the electric motor 11 with single- or multi-phase alternating current, in this case with 3-phase alternating current.

The inverter 12 is preferably constructed from a plurality of transistor units, particularly preferably from a plurality of MOSFETs 302 or IGBTs.

The power factor correction filter 13 in turn supplies the inverter 12 with direct current, wherein a current input of the power factor correction filter 13 for supplying power to the compressor 1 is connectable to the grid connection point 2000 or is connected in the exemplary embodiment shown.

The power factor correction filter 13 preferably comprises a rectifier 131, in particular a passive rectifier, which in the exemplary embodiment shown is configured as a bridge rectifier based on diodes 301.

Furthermore, the power factor correction filter 13 comprises a step-up converter 132 connected downstream of the rectifier 131, which step-up converter, as active power factor correction filter, has at least one transistor unit which can be configured as a MOSFET 302 or as an IGBT.

In FIG. 3, the voltage present at the current input of the power factor correction filter 13 is specified by “u_ac”, the current strength in the interface between rectifier 131 and step-up converter 132 is specified by “i_pfc”, the voltage in the interface between power factor correction filter 13 and inverter 12 is specified by “u_dc”, the current strength at the input of the further load 2 is specified by “i_load” and the current strength at the grid connection point 2000 is specified by “i_grid”.

Said designations are used later with respect to the exemplary embodiment in FIG. 5.

The control device is configured at least to control the power factor correction filter 13.

The control device is configured to determine at least one current characteristic value of the further load 2, which describes a current consumption of the further load 2, and to control the power factor correction filter 13 at least in dependence of the determined at least one current characteristic value.

The illustrated compressor system 1000 permits harmonics generated by the further load 2 to be compensated in an advantageous manner by taking into account the at least one current characteristic value at the further load 2 during the controlling of the power factor correction filter 13 of the compressor 1 by the control device 14.

In this way, the compressor system 1000 can maintain normative specifications during the tapping of the electrical current from the grid current source without the further load 2 having to be structurally modified or supplemented by additional components, such as, for example, dissipative elements.

In this respect, an efficiently operable compressor system 1000 is provided, in which in particular energy losses are kept low.

FIG. 4 schematically shows the structure of a third exemplary embodiment of the compressor system 1000 according to the invention.

The compressor system 1000 according to the third exemplary embodiment differs here from the second exemplary embodiment merely in the configuration of the power factor correction filter 13, which in the present case has a totem-pole topology.

For this purpose, the power factor correction filter 13 preferably comprises a totem-pole PFC converter 135, whose current input is connected to the grid connection point 2000 and whose output is connected to the inverter 12, here for example via an interposed capacitance (see FIG. 4).

The totem-pole PFC converter 135 can be formed via a plurality of MOSFETs 302 or IGBTs, which can be arranged, for example and without limitation, in accordance with the electrical circuit diagram in FIG. 4.

An inductance 24 can preferably be connected upstream of the totem-pole PFC converter 135 with respect to an energy flow direction from the grid connection point 2000 to the electric motor 11.

The remaining structure substantially corresponds to that from FIG. 3 and will not be explained again at this point.

FIG. 5 schematically shows the structure of a control device 14 of a fourth exemplary embodiment of the compressor system according to the invention.

The compressor system comprises a compressor for compressing a working medium, which comprises an electric motor for providing a mechanical movement for compressing the working medium, an inverter, which supplies the electric motor with single- or multi-phase alternating current, a power factor correction filter 13, which supplies the inverter with direct current and whose current input for supplying power to the compressor is connectable to a grid connection point of a grid current source providing alternating current, and a control device 14, which is configured at least to control the power factor correction filter 13.

In addition to the compressor, the compressor system comprises at least one further electrical load. The compressor and the further load are provided to be connected to a same grid connection point of a grid current source providing alternating current, wherein for this case the control device 14 of the compressor is configured to determine at least one current characteristic value of the further load, which describes a current consumption of the further load, and to control the power factor correction filter 13 at least in dependence of the determined at least one current characteristic value of the further load.

The power factor correction filter of this exemplary embodiment preferably comprises a rectifier, in particular a passive rectifier, and a step-up converter connected downstream thereof, which comprises at least one transistor unit.

The further load and the compressor are connected in parallel at the grid connection point.

Except for the power factor correction filter 13 and the control device 14, the components of the compressor mentioned otherwise above are not illustrated in FIG. 5.

In the following, an explanation of the design of the control device 14 takes place to illustrate the sequences for controlling the power factor correction filter 13 taking place therein.

The control device 14 according to FIG. 5 can be used, for example, in the compressor system from FIG. 2 or from FIG. 3, but is not restricted to the use therein.

To explain the sequences, reference is made in part to the current variables “u_dc”, “u_ac”, “i_pfc” etc. from FIG. 3, which does not mean, however, that the control device 14 shown in FIG. 5 is intended to be restricted to the use in a compressor system according to FIG. 3. The reference to FIG. 3 is produced merely for better explanation of the sequences in the control device.

The control device 14 preferably comprises a voltage regulator 141, a current intensity regulator 142, a calculation model unit 143, a compensation unit 144 and a PWM calculation unit 145.

Furthermore, the compressor system comprises a current measuring means 15, preferably a voltage measuring means, at the grid connection point, a first current measuring means 133 of the power factor correction filter 13, a second current measuring means 134 of the power factor correction filter 13 and an operating data provision unit 23.

The first current measuring means 133 is arranged at an output of the rectifier of the power factor correction filter and in particular configured to measure a current strength of the output current of the rectifier there. In the case of the exemplary embodiment from FIG. 3, this current strength would correspond to the current strength i_pfc there.

The second current measuring means 134 is arranged at an interface between power factor correction filter and inverter and in particular configured to measure a voltage there. In the case of the exemplary embodiment from FIG. 3, this voltage would correspond to the voltage u_dc there.

The current measuring means 15 at the grid connection point is in particular configured to measure a voltage there. In the case of the exemplary embodiment from FIG. 3, this voltage would correspond to the voltage u_ac there.

The operating data provision unit 23 contains operating data of the further load, in particular data relating to its rated operation, such as for example a rated power or a rated current strength. In the exemplary case in which the further load is a DC fan unit or a DC circulation pump, the operating data can be data relating to a rotational speed of the fan unit or a DC circulation pump, which describe either an absolute rotational speed or a ratio of the rotational speed to a rated rotational speed value.

Although the components 133, 134 in FIG. 5 are not drawn within the rectangle denoted by 13, they are nevertheless components of the power factor correction filter 13 in the exemplary embodiment shown. The second current measuring means 134 can alternatively also be configured as a component of the inverter.

The voltage regulator 141 is coupled to the second current measuring means 134 and receives its voltage measurement value as an input variable. Based on the received voltage measurement value and a correspondingly predetermined voltage setpoint value, the voltage regulator 141 is configured to determine a setpoint value for the current strength of the output current of the rectifier of the power factor correction filter.

The current intensity regulator 142 is coupled to the voltage regulator 141 and receives the setpoint value for the current strength determined by the latter as an input variable. Furthermore, the current intensity regulator 142 is coupled to the first measuring means 133 and receives its current intensity measurement value as a further input variable. Based on the received current intensity measurement value (as an actual value) and the received setpoint value for the current strength from the voltage regulator 141, the current intensity regulator 142 is configured to determine a first control signal for the power factor correction filter, so that the voltage in the interface between power correction factor and inverter follows the predetermined voltage setpoint value as far as possible.

The calculation model unit 143 is coupled to the operating data provision unit 23 and receives operating data of the further load from the latter as an input variable. The calculation model unit 143 provides a calculation model, which describes the electrical structure of the further load, comprising one or more electrical characteristic variables of the further load. The calculation model unit 143 is configured to determine the at least one current characteristic value of the further load on the basis of the provided calculation model and the input variable from the operating data provision unit 23, in particular in the form of a current strength, preferably in the form of amplitudes and phase angles of individual harmonics of the current, and to transmit these to the compensation unit 144. In the case of the exemplary embodiment from FIG. 3, the determined current strength would correspond to the current strength i_load there or would be an estimation thereof.

The compensation unit 144 is coupled to the calculation model unit 143 and receives the at least one current characteristic value determined by the latter, in this case the current strength, as an input variable. Furthermore, the compensation unit 142 is coupled to the first measuring means 133 and receives its current intensity measurement value as a further input variable. Based on the received current intensity measurement value and the determined at least one current characteristic value, the compensation unit 144 is configured to determine a current strength at the mains connection point. In the case of the exemplary embodiment from FIG. 3, the determined current strength would correspond to the current strength i_grid there or would be an estimation thereof.

Preferably, the respective variables described above are detected as time profiles or the variables determined therefrom are determined as time profiles.

Based on the determined current strength at the grid connection point, the compensation unit 144 is in turn configured to determine a compensation signal and to transmit this to the PWM calculation unit 145.

In this case, the compensation signal is determined under the provision of reducing the harmonic content of the current at the grid connection point.

The PWM calculation unit 145 now receives the first control signal from the current intensity regulator 142, the compensation signal from the compensation unit 144 and the voltage measurement value of the current measuring means 15 at the grid connection point and determines on the basis thereof a PWM control signal for the transistor unit of the power factor correction filter 13, which is transmitted from the PWM calculation unit to the transistor unit.

The transistor actuated in this manner permits harmonics generated by the further load to be compensated in an advantageous manner by the controlling of the power factor correction filter of the compressor.

In this way, the compressor system can maintain normative specifications during the tapping of the electrical current from the grid current source without the further load having to be structurally modified or supplemented by additional components, such as, for example, dissipative elements.

In this respect, an efficiently operable compressor system is provided, in which in particular energy losses can be kept low.

Exemplary embodiments of the present invention and the advantages thereof have been described in detail above with reference to the attached figures.

It is emphasized again that the present invention is in no way limited to the exemplary embodiments described above and their exemplary features. The invention further comprises modifications of the specified exemplary embodiments, in particular those which result from modifications and/or combinations of individual or a plurality of features of the described exemplary embodiments within the scope of protection of the independent claims.

LIST OF REFERENCE SIGNS

• • 1 compressor
  • 2 further Load
  • 11 electric motor
  • 12 inverter
  • 13 power factor correction filter
  • 14 control device
  • 15 current measuring means at the grid connection point (voltage measuring means)
  • 21 rectifier of the further load
  • 22 DC load
  • 23 operating data provision unit
  • 24 inductance
  • 131 rectifier
  • 132 step-up converter
  • 133 first current measuring means of the power factor correction filter
  • 134 second current measuring means of the power factor correction filter (voltage measuring means)
  • 135 totem-pole PFC converter
  • 141 voltage regulator
  • 142 current intensity regulator
  • 143 calculation model unit
  • 144 compensation unit
  • 145 PWM calculation unit
  • 301 diode
  • 302 transistor (MOSFET)
  • 1000 compressor system
  • 2000 grid connection point